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DESCRIPTION JPH06161643

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DESCRIPTION JPH06161643
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention inputs
information by contacting the surface of a substrate provided with ultrasonic wave transmitting /
receiving means with an input pen, and displays information on a display screen provided on the
other surface of the substrate. The present invention relates to an ultrasound learning apparatus
that displays
[0002]
2. Description of the Related Art A conventional personal computer mainly uses a keyboard as an
input means. Keyboard operations are complicated, time-consuming, and prone to errors, which
has been a major obstacle for beginners. Also, the conventional personal computer is generally
large because the keyboard portion and the display portion are independent.
[0003]
Transparent electrode-type and optical touch panels are mainly used in pen input computers that
can be input by directly writing characters, symbols, and other information on a panel. These
touch panels have problems in processability, durability, sensitivity, and the like, are susceptible
to malfunction due to the surrounding environment such as light, and have a disadvantage that
high-density information is difficult to display on a panel. A pen input computer is made possible
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by applying a touch panel. As a conventional touch panel, other than the above, a method using a
resistive film and a method using an ultrasonic wave are mainly mentioned. The method of using
a resistive film is such that the resistance value of the transparent conductive film changes by
touching the transparent conductive film (resistance film), and the response time, sensitivity,
durability, etc. of low power consumption. I have a problem in point. In the method using
ultrasonic waves, the surface acoustic wave is attenuated by touching the non-piezoelectric
substrate on which the surface acoustic wave is excited in advance. As a conventional method of
exciting surface acoustic waves on a non-piezoelectric substrate, a method of indirectly exciting
by a wedge-shaped transducer using a bulk wave oscillator, a method of exciting directly by a
piezoelectric thin film transducer, and the like can be mentioned. Wedge transducers are used for
nondestructive inspection by ultrasonic waves, etc., but are used only in a relatively low
frequency region due to problems with the processing accuracy of the wedge angle and the like.
A piezoelectric thin film transducer is a method of exciting a surface acoustic wave by an
interdigital electrode by vapor deposition of a piezoelectric thin film such as ZnO on a substrate,
and is used as a high frequency device because it shows various transmission characteristics by
the configuration of the interdigital electrode. It is limited to the VHF band and there are
problems with processability and mass productivity. Thus, in the conventional method, there are
problems in response time, sensitivity, durability, machining accuracy, machinability, mass
productivity, and the like, and the use frequency range is also limited.
[0004]
SUMMARY OF THE INVENTION It is an object of the present invention to provide high-density
information which is excellent in processability, durability and mass productivity, has low power
consumption and low voltage drive, and has high sensitivity by contacting a panel. Another
object of the present invention is to provide an ultrasonic learning apparatus which can be input
and can display information on the panel, which is compact, lightweight, thin, convenient to
carry, and easy to operate.
[0005]
The ultrasonic learning apparatus according to claim 1 comprises at least two ultrasonic wave
transmitting and receiving means on one plate surface Z1 of the substrate and on the other plate
surface Z2 of the substrate. An interactive ultrasonic wave comprising a display screen, learning
information input means for inputting learning information by bringing the pen tip of the input
pen into contact with the plate surface Z1, and learning information processing means having
learning information storage means In the learning apparatus, the ultrasonic wave transmitting /
receiving means includes N sets of interdigital electrodes Pi (i = 1, 2,..., N) and N sets of
interdigital electrodes respectively corresponding to the interdigital electrodes Pi. A group Qi (i =
1, 2,..., N), and the interdigital electrode group Qi includes at least two pairs of interdigital
electrodes Qi-1 (i = 1, 2,..., N) and Qi. -2 (i = 1, 2,..., N), and the interdigital transducer By inputting
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an electrical signal of at least one kind of frequency substantially corresponding to the electrode
period length of Pi to the interdigital electrode Pi, at least one kind of surface acoustic wave
having a wavelength substantially equal to the electrode period length is the plate surface
Electrical signal input means for exciting to Z1; electrical signal detecting means for detecting
electrical signals appearing on the interdigital electrodes Qi-1 and Qi-2 according to the
wavelength of the surface acoustic wave excited on the plate surface Z1; The respective output
ends of the interdigital electrodes Qi-1 are electrically connected to each other at the connection
point N1, and the respective output ends of the interdigital electrodes Qi-2 are electrically
connected to each other A propagation path of surface acoustic waves between the interdigital
electrode Pi and the interdigital electrode group Qi in one of the ultrasonic wave transmitting
and receiving means connected by N2, and the other ultrasonic wave in the ultrasonic wave
transmitting and receiving means Interdigital The propagation path of the surface acoustic wave
between the pole Pi and the interdigital transducer group Qi is orthogonal to each other, and the
electric signal detection means is configured to set the propagation path of the surface acoustic
wave on the plate surface Z1 to a part of the propagation path. A means for sensing from the
magnitude of the electrical signal appearing at the junction points N1 and N2 that the pen tip has
come in contact, and the junction point N1 at which the magnitude of the electrical signal
outputted out of the junction points N1 and N2 changes. Or means for identifying a contact
portion in the propagation path contacted by the pen point from the position of N2, and the
learning information processing means is input by the input pen based on the position of the
contact portion Learning information detecting means for detecting learning information, means
for causing the display screen to display the learning information detected by the learning
information detecting means for a predetermined time, and the learning information displayed
on the display screen Another learning information; and a means for displaying on the display
screen according to the information.
[0006]
In the ultrasonic learning apparatus according to claim 2, the electric signal input means has N
switches Si (i = 1, 2,...,) Whose output end is connected to the input end of the interdigital
transducer Pi. N) and switch control means for electrically switching on and off the switch Si
sequentially in a predetermined cycle, the respective input ends of the switch Si being electrically
connected to each other at the connection point NS, the connection point N1 is electrically
connected to the connection point NS via an amplifier, and a propagation path Di (i = 1, 1) of the
surface acoustic wave formed of the substrate between the interdigital electrode Pi and the
interdigital electrode Qi-1. An oscillator Hi (i = 1, 2,..., N) having a delay element 2,..., N) is
configured, and a signal loop of the oscillator Hi is the interdigital electrode Pi and the
propagation path Di. And the interdigital transducer Qi-1 and the amplifier It is characterized by
[0007]
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In the ultrasonic learning apparatus according to claim 3, there are at least two of L1 and L2 in
the electrode period lengths of the interdigital electrodes Pi, Qi-1 and Qi-2, respectively, and the
electric signal input means is the electrode Excitation of a surface acoustic wave having a
wavelength substantially equal to the electrode period length L1 or L2 to the plate surface Z1 by
inputting an electrical signal of a frequency substantially corresponding to the period length L1
or L2 to the interdigital transducer Pi It features.
[0008]
The ultrasonic learning apparatus according to claim 4, wherein the learning information storage
means stores in advance a table having learning information in which the position on the plate
surface Z1 is an address and the learning information corresponding to the position is data. The
information detecting means inputs the position of the contact portion as the address by the
learning information storage means, and uses the data read from the address as the learning
information inputted by the learning information input means. .
[0009]
In the ultrasonic learning apparatus according to claim 5, the learning information storage means
prestores patterns such as characters and symbols, and the learning information detection means
is a locus formed by the movement of the position of the contact portion. And the pattern read
from the learning information storage means, and the learning information input by the learning
information input means is detected by a pattern matching method.
[0010]
The ultrasonic learning apparatus according to claim 6 is characterized in that the learning
information detecting means sets the position of the contact portion as the learning information
input by the learning information input means.
[0011]
The ultrasonic learning device according to claim 7, wherein the learning information input
means displays the learning information on the display screen in at least two colors, and the
electric signal input means has an electrode cycle length of the interdigital electrode Pi And at
least two types of surface acoustic waves having a wavelength approximately equal to the
electrode period length are excited to the plate surface Z1 by inputting electrical signals of at
least two types of frequencies substantially corresponding to A means is provided for correlating
the frequency with the color of the learning information.
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[0012]
The ultrasonic learning device according to claim 8, wherein the substrate is made of a
substantially transparent piezoelectric ceramic, and the direction of the polarization axis of the
piezoelectric ceramic is parallel to the thickness direction of the piezoelectric ceramic, and the
interdigital transducer Pi The interdigital transducer group Qi is provided on the plate surface
Z1.
[0013]
In the ultrasonic learning device according to claim 9, the substrate is made of a nonpiezoelectric material, the ultrasonic wave transmitting and receiving means is made of
ultrasonic devices A and B, and the ultrasonic device A is in the shape of an interdigital The
ultrasonic device B is characterized in that the ultrasonic device B is constituted by providing the
interdigital transducer group Qi on a piezoelectric thin plate b, and the piezoelectric thin plates a
and b are provided on the plate surface Z1.
[0014]
In the ultrasonic learning device according to claim 10, the thickness of the piezoelectric thin
plate a is equal to or less than the electrode cycle length of the interdigital electrode Pi, and the
thickness of the piezoelectric thin plate b is the interdigital electrodes Qi-1 and Qi. The
periodicity of the interdigital electrodes Pi, Qi-1 and Qi-2 is equal to or less than that of the
surface acoustic wave of the first mode or the second or higher order mode, It is characterized in
that the phase velocity of the surface acoustic wave in the next mode or the second or higher
order mode is approximately equal to the propagation velocity of the surface acoustic wave
excited on the single substrate.
[0015]
The ultrasonic learning device according to claim 11 is characterized in that the piezoelectric
thin plate a or b is made of a piezoelectric ceramic, and the direction of the polarization axis of
the piezoelectric ceramic is parallel to the thickness direction of the piezoelectric ceramic.
[0016]
The ultrasonic learning device according to claim 12 is characterized in that the piezoelectric
thin plate a or b is made of PVDF or other polymeric piezoelectric film.
[0017]
The ultrasonic learning device according to claim 13 is characterized in that the piezoelectric
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thin plate a or b is fixed to the plate surface Z1 via the plate surface on which the interdigital
electrode is provided.
[0018]
The ultrasonic learning apparatus according to the present invention comprises at least two
ultrasonic wave transmitting / receiving means on one plate surface Z1 of the substrate, an
information input means having a display screen on the other plate surface Z2 of the substrate,
and information storage By having a simple structure including an information processing means
provided with means, it is possible to reduce the size, weight and thickness of the device.
The ultrasonic wave transmitting / receiving means comprises N sets of interdigital electrodes Pi
(i = 1, 2,..., N) and N sets of interdigital electrodes Qi (i = 1, 2,...) Respectively corresponding to the
interdigital electrodes Pi. , And N), and the interdigital electrode group Qi includes at least two
pairs of interdigital electrodes Qi-1 (i = 1, 2,..., N) and Qi-2 (i = 1, 2,. ..., N).
Surface acoustic wave can be excited on the plate surface Z1 of the substrate by adopting a
structure in which the interdigital transducer Pi is used as an input and an electric signal is
inputted from the interdigital transducer Pi.
Moreover, the surface acoustic wave can be excited on the surface Z1 efficiently with low power
consumption and low voltage.
[0019]
The interdigital electrodes Qi-1 and Qi-2 are used for output, and the interdigital electrodes Qi-1
and Qi-2 are arranged so that the directivity axes of transmission and reception of surface
acoustic waves are common to the interdigital electrode Pi. By adopting such a structure, the
surface acoustic wave excited on the plate surface Z1 can be efficiently output as an electric
signal.
Excitation is made on the surface Z1 by contacting the surface acoustic wave propagation path
on the surface Z1 (ie, between the interdigital electrodes Pi and Qi-1 and between Pi and Qi-2)
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with the pen tip of the input pen Since the surface acoustic wave that is being annihilated or
attenuated, the electrical signals output to the interdigital electrodes Qi-1 and Qi-2 are also
annihilated or attenuated.
Thus, it can be sensed that the pen tip contacts the propagation path of the surface acoustic wave
on the surface Z1.
Moreover, the ultrasound learning device of the present invention has a short response time and
good sensitivity.
The pen point needs to be made of a material that is softer than the substrate and easily absorbs
ultrasonic waves, and a human finger or the like also has that feature.
Further, it is possible to identify the contact portion touched by the pen tip by discriminating the
interdigital electrode from which the output electric signal disappears or attenuates among the
interdigital electrodes Qi-1 and Qi-2.
[0020]
By adopting a structure for inputting an electrical signal of at least one frequency substantially
corresponding to the electrode period length of interdigital electrode Pi to interdigital electrode
Pi, at least plate having a wavelength approximately equal to the electrode period length on plate
surface Z1 One type of surface acoustic wave can be excited.
Further, the surface acoustic wave excited on the plate surface Z1 can be output as an electric
signal from the interdigital electrodes Qi-1 and Qi-2 in accordance with the wavelength.
[0021]
A structure in which at least two ultrasonic wave transmitting and receiving means are provided
on the plate surface Z1 and propagation paths of surface acoustic waves between the interdigital
electrode Pi and the interdigital electrode group Qi in one ultrasonic wave transmitting and
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receiving means By adopting a structure in which the surface acoustic wave propagation paths
between the interdigital electrode Pi and the interdigital electrode group Qi in another ultrasonic
wave transmitting and receiving means are orthogonal to each other, the contact portion in the
plate surface Z1 is further It can be identified delicately.
This can be more finely specified as the number of ultrasonic wave transmitting and receiving
means increases.
[0022]
By connecting the output ends of the interdigital electrodes Qi-1 to each other electrically at the
connection point N1, and connecting the respective output ends of the interdigital electrodes Qi2 to each other at the connection point N2, the plate surface is obtained. It can be sensed from
the magnitude of the electric signal appearing at the connection point N1 and the connection
point N2 that the pen tip contacts a part of the propagation path of the surface acoustic wave at
Z1.
As means for inputting an electric signal to the interdigital transducer Pi, N switches Si (i = 1, 2,...,
N) whose output end is connected to the input of the interdigital transducer Pi are provided. A
structure is employed in which the switches Si are electrically interrupted one after another in a
predetermined cycle.
In this way, electrical signals can be sequentially input to the interdigital transducer Pi.
Therefore, among propagation paths of surface acoustic waves on plate surface Z1 (ie, between
interdigital electrodes Pi and Qi-1 and between Pi and Qi-2), for example, between interdigital
electrodes P1 and Q1-1. When the electric signal is input to the interdigital transducer P1, the
delayed electric signal output to the connection point N1 is attenuated or extinguished.
In this way, it is possible to clearly specify the contact position.
[0023]
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By adopting a structure in which respective input ends of switches Si are electrically connected
to each other at connection point NS, and connection point N1 is electrically connected to
connection point NS via an amplifier, interdigital electrodes Pi to Qi- An oscillator Hi (i = 1, 2,...,
N) having as a delay element a propagation path Di (i = 1, 2,..., N) of a surface acoustic wave
consisting of a plate surface Z1 between 1 and can do. The signal loop of the oscillator Hi
comprises an interdigital electrode Pi, a propagation path Di, an interdigital electrode Qi-1, and
an amplifier. In this manner, since the circuit configuration is simplified, the reduction in size and
weight of the device is further promoted, and furthermore, low power consumption and low
voltage driving can be achieved.
[0024]
By adopting a structure having at least two electrode period lengths L1 and L2 respectively as
interdigital electrodes Pi, Qi-1 and Qi-2, the interdigital electrode Pi has a frequency substantially
corresponding to the electrode period L1 or L2 An electrical signal can be input. Therefore, it is
possible to excite the surface acoustic wave having a wavelength substantially equal to the
electrode period length L1 or L2 on the plate surface Z1. In addition, surface acoustic waves
having a wavelength substantially equal to the electrode period L1 or L2 excited on the plate
surface Z1 can be output as an electrical signal from the interdigital electrodes Qi-1 and Qi-2. By
arranging the interdigital electrode Pi and the interdigital electrode group Qi in the ultrasonic
wave transmitting / receiving means such that the electrode fingers having a smaller electrode
cycle length are inside each other, that is, the interelectrode distance is reduced, The attenuation
of the surface acoustic wave excited to Z1 can be suppressed. This is to solve the problem that
the surface acoustic wave of a high frequency is excited on the plate surface Z1 as the electrode
cycle length is smaller, and the surface acoustic wave of a high frequency is more easily
attenuated.
[0025]
In the information input means of the ultrasonic learning apparatus of the present invention,
information is input by bringing the pen point of the input pen into contact with the plate surface
Z1. In addition, a structure in which information is displayed on the display screen by the contact
is adopted. Information on the display screen can be viewed as it is via the plate surface Z1. That
is, a structure in which the display and the keyboard are integrated is adopted. Moreover, the
transparency of the display screen seen through the plate surface Z1 is excellent. Therefore,
while the size and weight reduction and thickness reduction of the device are further promoted,
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the screen is clear, and moreover, even a beginner can easily operate. Further, in the ultrasonic
learning apparatus according to the present invention, a structure is adopted in which
information corresponding to the position of the contact portion is displayed on the display
screen for a predetermined time. However, the information is information to be input from now,
or information that is already stored and output to the display screen based on the position of
the contact portion. Therefore, when inputting information such as characters, the characters can
be displayed on the display screen by drawing characters and the like on the surface Z1 with the
pen tip. In this manner, by directly writing characters, symbols, and other information on the
surface Z1, not only the information can be input, but also it can be displayed as an image on the
display screen. Moreover, it is also possible to output information already stored on the display
screen by contacting a predetermined portion of the plate surface Z1. Furthermore, in the
ultrasonic learning apparatus according to the present invention, a structure is adopted in which
another learning information is displayed on the display screen according to the learning
information displayed on the display screen. In this way, the ultrasonic learning apparatus of the
present invention enables interactive learning. For example, a series of operations such as first
displaying a problem on a screen, secondly writing in the answer of the problem on a screen, and
thirdly displaying a model answer on a screen can be performed on the same screen.
[0026]
In the ultrasonic learning apparatus according to the present invention, as information
processing means, information input based on the means for specifying the contact portion in the
plate surface Z1 contacted by the pen tip and the position of the contact portion specified by the
contact portion identification means And input information detecting means for detecting the
information input by the means. Further, the information processing means of the ultrasonic
learning apparatus of the present invention comprises an information storage means. By
adopting a structure in which a table in which the position on the surface Z1 is an address and
the information associated with the position is stored as the information storage means is stored,
the position of the contact portion is input as an address. Therefore, stored data can be read out
from the address. Also, by adopting a structure in which patterns such as characters and symbols
are stored in advance as information storage means, a locus formed by the movement of the
position of the portion to be touched is input, and the locus is compared with the pattern. And
the information indicated by the locus is recognized. Therefore, it becomes possible to input
information such as characters drawn on the surface Z1.
[0027]
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By adopting a structure in which information is displayed in at least two colors as the display
screen, and by adopting a structure in which the frequency of the electric signal input to the
interdigital transducer Pi corresponds to the color of the display screen By switching the
frequency to the location, it becomes possible to input separately color-coded information. That
is, it is possible to input color-coded information for each frequency by contacting the portion on
the plate surface Z1 for each frequency. Therefore, it also increases the amount of input
information.
[0028]
By using a translucent piezoelectric ceramic such as La-doped zircon-lead titanate (PLZT) as a
substrate, and adopting a structure in which the direction of the polarization axis of the
piezoelectric ceramic is parallel to the thickness direction. Surface acoustic waves can be
efficiently excited on the substrate. At this time, the interdigital electrode Pi and the interdigital
electrode group Qi are provided directly on the substrate. Further, by adopting a substantially
transparent structure as the piezoelectric ceramic, the information appearing on the display
screen can be viewed from above the plate surface Z1. In order to propagate the surface acoustic
wave to the surface Z1 of the substrate made of piezoelectric ceramic, it is desirable that the
thickness of the substrate is at least three times the electrode period length of the interdigital
electrodes Pi, Qi-1 and Qi-2. In the case where the thickness of the substrate is smaller than the
electrode cycle length and the thickness is thin, Lamb waves propagate, but if there is a mode
that can function as a touch panel, it is possible to use Lamb waves. As the substrate, in addition
to the piezoelectric ceramic, single crystals such as LiNbO3 and LiTaO3 can be considered.
Although these single crystals are promising as substrates because they are transparent and
piezoelectric, they have anisotropy as crystals, so they need to be devised at the design stage
including the electromechanical coupling coefficient. Not only that, but it may require extra
electronic circuitry. Among piezoelectric ceramics, PLZT is promising as a substrate because it is
transparent and is excellent in piezoelectricity, processability and durability. Propagation path of
surface acoustic wave between interdigital transducer electrode Pi and interdigital transducer
group Qi in one ultrasonic wave transmitting and receiving means by utilizing isotropy in the
plane of plate surface Z1 of the substrate made of PLZT And the propagation path of the surface
acoustic wave between the interdigital transducer Pi and the interdigital transducer group Qi in
another ultrasonic wave transmitting and receiving means are orthogonal to each other. The level
of the electrical signal output to one interdigital transducer group Qi can be made substantially
the same. Therefore, the circuit configuration is simplified and not only the reduction in size and
weight of the device can be promoted, but also the output signal can always be made uniform, so
that the signal processing becomes accurate and the sensitivity is improved. Furthermore, since
the resolution is also increased, the amount of input information can be increased.
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[0029]
A non-piezoelectric body is adopted as a substrate, and an ultrasonic wave transmitting /
receiving means is constituted by ultrasonic devices A and B, and an ultrasonic device A is
provided with an interdigital electrode Pi on a piezoelectric thin plate a. Since the interdigital
transducer group Qi is provided on the piezoelectric thin plate b, it is possible to excite the
surface acoustic wave of the first mode or the second or higher mode to the plate surface Z1 of
the substrate in a portion contacting the interdigital electrode Pi. . At this time, by adopting a
structure in which the phase velocity of the surface acoustic wave is substantially equal to the
propagation velocity of the surface acoustic wave in the single substrate, the electrical energy
applied from the interdigital electrode Pi is converted into the surface acoustic wave. Not only it
is possible to increase the degree, it is possible to remove the reflection and the like caused by
the acoustic impedance mismatch and the like at the interface between the piezoelectric thin
plate and the substrate. In this manner, the surface acoustic wave can be efficiently excited on
the surface Z1 of the substrate with low power consumption and without applying a high voltage.
In addition, the area of the substrate can be made relatively large, which enables a wide range of
applications. The piezoelectric thin plates a and b are provided on the plate surface Z1.
[0030]
The thickness of each of the piezoelectric thin plates a and b in the ultrasonic devices A and B is
made equal to or less than the electrode period length of the interdigital electrode, and the
electrode period length of the interdigital electrode is the surface acoustic wave of the first mode
or second or higher mode By adopting a structure approximately equal to the wavelength, it is
possible not only to increase the degree to which the electrical energy applied from the
interdigital electrode is converted to surface acoustic waves, but also between the piezoelectric
thin plate and the nonpiezoelectric substrate. It is possible to remove reflections and the like
caused by acoustic impedance mismatching at the interface. The smaller the ratio (d / λ) of the
thickness d of the piezoelectric thin plate to the electrode period length of the interdigital
transducer, that is, the wavelength λ of the surface acoustic wave, the larger the effect.
[0031]
By adopting a structure in which a piezoelectric ceramic is adopted as the piezoelectric thin
plates a and b and the direction of the polarization axis of the piezoelectric ceramic is parallel to
the thickness direction, the substrate made of non-piezoelectric material can be efficiently
subjected to the first mode or 2 It is possible to excite surface acoustic waves of the following
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modes or more.
[0032]
By employing PVDF or other polymeric piezoelectric film as the piezoelectric thin plate, it is
possible to efficiently excite the surface acoustic wave of the first mode or the second or higher
mode on the non-piezoelectric substrate.
[0033]
By adopting a structure in which the interdigital transducer is provided at the interface between
the non-piezoelectric substrate and the piezoelectric thin plate, the electrical energy applied to
the interdigital transducer can be efficiently converted to surface acoustic waves.
[0034]
The ultrasonic learning apparatus according to the present invention is an instruction of
processing by touching the surface Z1 with a dedicated input pen, recognition of handwritten
characters, character input such as kana-kanji conversion, drawing of figures and pictures, line
feed / insertion / deletion etc. The operation can be easily performed by beginners.
In addition, it is also possible to connect an optional external keyboard, and keyboard input is
also possible.
It is also compatible with communication functions, and printers and external CRTs can also be
connected.
Therefore, the ultrasonic learning apparatus according to the present invention is not limited to
the case where the problem is solved by the individual utilizing the interactive function, but
learning such as having a third party reply an exemplary reply using the communication function
A wide range of applications as devices are possible.
[0035]
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DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a perspective view showing an
embodiment of an ultrasonic learning apparatus according to the present invention. This
embodiment comprises a touch panel unit 1, an information processing unit 2 (not shown in FIG.
1 because it is provided inside the main body), a power switch 3, a disk insertion chamber 4, an
input pen storage chamber 5 and a cover 6. . The input pen storage room 5 contains an input
pen. In use, the cover 6 is lifted as shown in FIG. When the power switch 3 is turned ON, the
procedure of the operation is displayed in order on the touch panel unit 1. According to the
instruction, the designated part of the touch panel unit 1 is touched with an input pen to input
information or save The displayed information can be projected on the touch panel unit 1. In this
way, by touching the touch panel portion 1, instructions for processing, recognition of
handwritten characters, character input such as kana-kanji conversion, drawing of figures and
pictures, operations such as line feed / insertion / deletion are also available to beginners
without a manual. It can be done easily. When characters, symbols, and other information are
written on the touch panel unit 1 by the input pen, the information is sent to the information
processing unit 2, processed, and displayed on the touch panel unit 1. When the information is
stored in a predetermined disk, the disk is inserted into the disk insertion chamber 4. In addition,
it is also possible to connect an optional external keyboard, and keyboard input is also possible. It
can also handle communication functions, and can also connect a printer, an external CRT, etc.
The ultrasound learning apparatus of the present invention has an interactive function. For
example, when an individual solves a problem, firstly, the problem is displayed on the touch
panel unit 1, secondly, the answer to the problem is written in the touch panel unit 1, and thirdly,
the model answer is displayed on the touch panel unit 1 The above operation is possible on the
same touch panel unit 1. A wide range of application as a learning apparatus is possible, such as
having a third party send back an exemplary answer using a communication function as well as
solving the problem individually.
[0036]
FIG. 2 is a plan view showing an embodiment of the touch panel unit 1. The touch panel unit 1
comprises ultrasonic devices 7, 8, 9, 10, a glass substrate 11, and a display screen 12 (not shown
in FIG. 2). The ultrasonic device 7 is provided with interdigital electrodes T1 and T2 on a
piezoelectric ceramic thin plate 13. The ultrasonic device 8 is provided with interdigital
electrodes T3 and T4 on a piezoelectric ceramic thin plate 13. The ultrasonic device 9 is provided
with interdigital electrodes R11, R12, R13, R14, R21, R22, R23 and R24 on a piezoelectric
ceramic thin plate 13. The ultrasonic device 10 is provided with interdigital electrodes R31, R32,
R33, R34, R41, R42, R43 and R44 on the piezoelectric ceramic thin plate 13. The piezoelectric
ceramic thin plate 13 is made of TDK 101A material (product name) having a thickness of 230
μm. Each interdigital transducer comprises an aluminum thin film. The glass substrate 11 is
made of Pyrex glass of 70 mm in length, 55 mm in width, and 1.9 mm in thickness. The
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piezoelectric ceramic thin plate 13 is provided on the glass substrate 11. The display screen 12 is
provided on the other surface of the glass substrate 11. The piezoelectric ceramic thin plate 13 is
fixed on the glass substrate 11 by an epoxy resin having a thickness of about 20 μm. Each
interdigital transducer is a regular type having an electrode cycle length of 840 μm and 7.5
pairs of electrode fingers. When the touch panel unit 1 is mounted on the ultrasonic learning
apparatus of FIG. 1, the touch panel unit 1 is mounted in such a manner that the plate surface of
the one provided with each ultrasonic device faces the outside. It is mounted so that only the
area surrounded by each ultrasonic device is exposed to the outside.
[0037]
FIG. 3 is a plan view showing ultrasonic devices 7 and 9 in the touch panel unit 1 of FIG. The
ultrasound devices 7 and 9 are in line with each other. The relationship between the ultrasound
devices 8 and 10 is also similar to the relationship between the ultrasound devices 7 and 9.
Interdigital electrodes T1, T2, T3 and T4 are used for input, and the electrode crossover width is
18 mm. Interdigital electrodes R11 to R14, R21 to R24, R31 to R34, and R41 to R44 are used for
output, and the electrode crossover width is 2.7 mm. The interdigital electrodes R11 to R14
correspond to the interdigital electrodes T1, the interdigital electrodes R21 to R24 correspond to
the interdigital electrodes T2, and the interdigital electrodes R31 to R34 correspond to the
interdigital electrodes T3, and the interdigital electrodes R41 R44 corresponds to the interdigital
transducer T4.
[0038]
FIG. 4 is a cross-sectional view of the touch panel unit 1 of FIG. 2 and shows the relationship
between the input ultrasonic device and the output ultrasonic device. An input interdigital
transducer and an output interdigital transducer are provided on the glass substrate 11 side of
the piezoelectric ceramic thin plate 13.
[0039]
FIG. 5 is a plan view showing an example of an interdigital electrode used in place of the
interdigital electrodes used in the touch panel unit 1 of FIG. This interdigital electrode is a
regular type having an electrode cycle length of 620 μm, 5 pairs of electrode fingers, and an
electrode cycle length of 295 μm, and 5 pairs of electrode fingers. When used, electrode fingers
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having an electrode cycle length of 295 μm are arranged to be inside each other. This is in
consideration of the fact that the surface acoustic wave of a high frequency is excited to the glass
substrate 11 as the electrode cycle length is smaller, and the higher the frequency surface
acoustic wave, the more easily it is attenuated. In this manner, the propagation path length of the
surface acoustic wave (that is, the distance between the electrodes) decreases as the electrode
period length decreases.
[0040]
FIG. 6 is a block diagram of the case where the touch panel unit 1 of the ultrasonic learning
apparatus of FIG. 1 is driven using an rf pulse. FIG. 7 is a waveform diagram of each part in the
configuration diagram of FIG. When the touch panel unit 1 is driven, continuous waves generated
by the signal generator are respectively double balanced mixers (D.B.M.) 1 and D.D. B. M.
Modulated by 2 into rf pulses -1 and -2. D. B. M. 1 and D. B. M. 2 plays a role of switching and
applies an rf pulse to interdigital electrodes T1 and T3 (hereinafter referred to as T1 group) or an
rf pulse to interdigital electrodes T2 and T4 (hereinafter referred to as T2 group) There is. When
an rf pulse is applied to the interdigital electrodes of the T1 group, only rf pulses having a
frequency substantially corresponding to the electrode period length of the interdigital
electrodes of the T1 group are converted to surface acoustic waves and the input ultrasonic
device 7 and It propagates through the eight piezoelectric ceramic thin plates 13 and further
propagates through the glass substrate 11. Of the surface acoustic waves propagating through
the glass substrate 11, of the wavelength substantially equal to the electrode period length
indicated by the interdigital electrodes R11 to R14 of the output ultrasonic device 9 and the
interdigital electrodes R31 to R34 of the output ultrasonic device 10 Only surface acoustic waves
are converted into delayed electrical signals and output from interdigital electrodes R11 to R14
and R31 to R34 (hereinafter referred to as R1 group). When an rf pulse is applied to the
interdigital electrodes of the T2 group, only rf pulses having a frequency substantially
corresponding to the electrode period length of the interdigital electrodes of the T2 group are
converted to surface acoustic waves and the input ultrasonic device 7 and It propagates through
the eight piezoelectric ceramic thin plates 13 and further propagates through the glass substrate
11. Of the surface acoustic waves propagating through the glass substrate 11, of the wavelength
substantially equal to the electrode period length indicated by the interdigital electrodes R21 to
R24 of the output ultrasonic device 9 and the interdigital electrodes R41 to R44 of the output
ultrasonic device 10 Only surface acoustic waves are converted into delayed electrical signals
and output from interdigital electrodes R21 to R24 and R41 to R44 (hereinafter referred to as R2
group). Thus, delayed electrical signals can be alternately output to the interdigital electrodes of
the R1 group and the R2 group by alternately inputting the electrical signals to the interdigital
electrodes of the T1 group and the T2 group. Connecting the interdigital electrodes R11 and
R21, R12 and R22, R13 and R23, R14 and R24, R31 and R41, R32 and R42, R33 and R43, and
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R34 and R44 not only simplifies the circuit configuration but also A form in which delayed
electric signals of two pairs of interdigital electrodes R11 and R21, R12 and R22, R13 and R23,
R14 and R24, R31 and R41, R32 and R42, R33 and R43, and R34 and R44 are overlapped.
Received by
Therefore, when an electrical signal is input to the interdigital transducer of the T1 group, if the
propagation path of the surface acoustic wave propagating through the glass substrate 11 is
contacted with a material softer than the glass substrate 11 and easily absorbing ultrasonic
waves, the T1 group The surface wave corresponding to the contact position is attenuated only
when an electric signal is input to the interdigital transducer. Similarly, when an electrical signal
is input to the interdigital transducer of the T2 group, the electrical signal is input to the
interdigital transducer of the T2 group when the propagation path of the surface acoustic wave
propagating to the glass substrate 11 is brought into contact The surface wave corresponding to
the contact position is attenuated only occasionally. Such delayed signals are amplified and
rectified into direct current signals, respectively. A digital signal is obtained in the comparator by
setting an appropriate threshold voltage value between the direct current voltage value
corresponding to the case where the glass substrate 11 is touched and the case where the glass
substrate 11 is not touched. This digital signal is taken into the computer as a parallel signal at
an appropriate timing by the computer.
[0041]
FIG. 8 is a block diagram of the case where the touch panel unit 1 of the ultrasonic learning
apparatus of FIG. 1 is driven by forming a delay line oscillator. The waveform diagram at each
part in the configuration diagram of FIG. 8 is the same as the waveform diagram shown in FIG. In
FIG. 8, between the interdigital electrodes T1 and R11 or between T2 and R21 is a first delay
element, and between the interdigital electrodes T3 and R31 or T4 and R41 is a second delay
element. A delay line oscillator is formed having a figure eight shaped signal loop. When the
touch panel unit 1 is driven, the switches 1, 2, 3 and 4 are operated by an instruction from the
computer. When switches 1 and 3 (hereinafter referred to as S1 group) are closed, switches 2
and 4 (hereinafter referred to as S2 group) are open. Thus, by opening and closing the switches
of the S1 group and the S2 group, electric signals are alternately inputted to the interdigital
electrodes T1 and T3 (hereinafter referred to as T1 group) and the interdigital electrodes T2 and
T4 (hereinafter referred to as T2 group). doing. Electrical signals input to the T1 group or T2
group are modulated to rf pulses -1 and -2, respectively, by clock pulses -1 and -2 from a
computer. When the switch of the S1 group is closed and the electrical signal -1 is input to the
interdigital transducer of the T1 group, only the electrical signal having a frequency substantially
corresponding to the electrode period length of the interdigital transducer of the T1 group is
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converted to surface acoustic wave And propagate through the piezoelectric ceramic thin plate
13 of the input ultrasonic devices 7 and 8 and further propagate through the glass substrate 11.
Among surface acoustic waves propagating through the glass substrate 11, elasticity of a
wavelength substantially equal to the electrode period length of the interdigital electrodes R11 to
R14 of the output ultrasonic device 9 and the interdigital electrodes R31 to R34 of the output
ultrasonic device 10 Only surface waves are converted into delayed electrical signals and output
from interdigital electrodes R11 to R14 and R31 to R34 (hereinafter referred to as R1 group).
When the switch of the S2 group is closed and the electrical signal-2 is input to the interdigital
transducer of the T2 group, only the electrical signal having a frequency substantially
corresponding to the electrode period length of the interdigital transducer of the T2 group is
converted to the surface acoustic wave And propagate through the piezoelectric ceramic thin
plate 13 of the input ultrasonic devices 7 and 8 and further propagate through the glass
substrate 11. Among surface acoustic waves propagating through the glass substrate 11,
elasticity of a wavelength substantially equal to the electrode period length of the interdigital
electrodes R21 to R24 of the output ultrasonic device 9 and the interdigital electrodes R41 to
R44 of the output ultrasonic device 10 Only surface waves are converted into delayed electrical
signals and output from interdigital electrodes R21 to R24 and R41 to R44 (hereinafter referred
to as R2 group).
Thus, delayed electrical signals can be alternately output to the interdigital electrodes of the R1
group and the R2 group by alternately inputting the electrical signals to the interdigital
electrodes of the T1 group and the T2 group. Connecting the interdigital electrodes R11 and
R21, R12 and R22, R13 and R23, R14 and R24, R31 and R41, R32 and R42, R33 and R43, and
R34 and R44 not only simplifies the circuit configuration but also A form in which delayed
electric signals of two pairs of interdigital electrodes R11 and R21, R12 and R22, R13 and R23,
R14 and R24, R31 and R41, R32 and R42, R33 and R43, and R34 and R44 are overlapped.
Received by However, a part of the electric signal output from the interdigital electrodes R11 and
R21 and a part of the electric signals output from the interdigital electrodes R31 and R41 among
the respective two pairs of interdigital electrodes are respectively the amplifier A and the
amplifier After being amplified by B and controlled to a predetermined phase by the respective
phase shifters, they are input again to the interdigital electrodes of the T1 group and the T2
group through the switches of the S1 group and the S2 group, respectively. That is, an electrical
signal input to the interdigital transducer T1 or T2 through the switch 1 or 2 passes through the
amplifier A, and then is input to the interdigital transducer T3 or T4 through the switch 3 or 4
this time. Further, the electric signal input to the interdigital transducer T3 or T4 through the
switch 3 or 4 passes through the amplifier B, and then is input to the interdigital transducer T1
or T2 through the switch 1 or 2 this time. In this way, a delay line oscillator having a figure eight
shaped signal loop is formed. By the way, the delayed electric signals output to the two pairs of
interdigital electrodes R11 and R21, R12 and R22, R13 and R23, R14 and R24, R31 and R41,
R32 and R42, R33 and R43, and R34 and R44 are It is attenuated by contacting the glass
13-04-2019
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substrate 11 (or). Propagation path of surface acoustic wave propagating through the glass
substrate 11 when an electric signal is input to the interdigital transducer of the T1 group
(between the interdigital transducers T1 and R11 to R14 and the interdigital transducers T3 and
R31 to R34 When contact is made with a substance that is softer than the glass substrate 11 and
tends to absorb ultrasonic waves), the surface wave corresponding to the contact position is
attenuated only when an electric signal is input to the interdigital transducer of the T1 group.
Similarly, propagation paths of surface acoustic waves propagating through the glass substrate
11 when an electric signal is input to the interdigital electrodes of the T2 group (between the
interdigital electrodes T2 and R21 to R24 and the interdigital electrode T4 When contacting with
R41 to R44), the surface wave corresponding to the contact position is attenuated only when an
electric signal is inputted to the interdigital transducer of the T2 group. Such delayed signals are
amplified and rectified into direct current signals, respectively. A digital signal is obtained in the
comparator by setting an appropriate threshold voltage value between the direct current voltage
value corresponding to the case where the glass substrate 11 is touched and the case where the
glass substrate 11 is not touched. This digital signal is taken into the computer as a parallel
signal at an appropriate timing by the computer. The drive method using this delay line oscillator
does not require a pulse generator, so the size and power consumption of the device can be
further reduced and the voltage can be reduced as compared with the case of driving using rf
pulses as shown in FIG. It is possible.
[0042]
When driving the ultrasonic learning apparatus of FIG. 1, color-coded information corresponding
to the touch position appears on the display screen 12 of the display device according to a
command from the computer. Moreover, a system is incorporated in which the frequency
corresponds to the frequency of the electrical signal input to the interdigital electrodes of the T1
group or the T2 group. The information on the display screen 12 can be viewed through the
glass substrate 11. In this way, when the propagation path of the surface acoustic wave
propagating through the glass substrate 11 is brought into contact, the surface acoustic wave
propagating through the propagation path is attenuated or extinguished, and accordingly, the
display screen 12 corresponds to the contact position. The color-coded information appears.
Moreover, by switching the frequency of the electric signal to be input, information is input with
a plurality of colors corresponding to the types of frequencies at the same position on the display
screen 12 by touching the glass substrate 11 at the same position. It is possible to That is, if two
types of frequencies are used, it becomes possible to input information that is color-coded by two
types of colors at the same position. In addition, a system is incorporated in which information in
a form corresponding to the contact position is displayed on the display screen for a
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predetermined time. In this manner, for example, when a character or the like is drawn on the
glass substrate 11 with a substance that is softer than the glass substrate 11 and easily absorbs
ultrasonic waves, the character can be displayed on the display screen 12. In the case of using
the interdigital electrode of FIG. 5 in the ultrasonic learning device of FIG. 1, since there are two
types of electrode cycle lengths of the interdigital electrode and the difference between the
respective values is large, The difference between the values of the frequencies of the two types
of input electrical signals can be increased. Moreover, since the frequency of the electrical signal
to be input can be further subdivided into several types substantially corresponding to the
electrode cycle length of each type, as a result, the type of frequency of the electrical signal to be
input can be further increased.
[0043]
FIGS. 9 and 10 are characteristic diagrams showing the relationship between insertion loss and
frequency between interdigital electrodes T1 and R11. However, FIG. 9 shows the case where the
top of the glass substrate 11 is not in contact, and FIG. 10 shows the case where the top of the
glass substrate 11 is in contact. The peak near 3.96 MHz corresponds to the surface acoustic
wave in the first mode. Focusing on the first-order surface acoustic wave, it can be seen that the
difference in insertion loss between contact and non-contact is about 10 dB. The change in the
insertion loss is a sufficient change for the signal processing of the touch panel unit 1.
[0044]
FIGS. 11 and 12 show the response characteristics between the interdigital electrodes T1 and
R11 in the case where an rf pulse of 3.96 MHz is applied. However, FIG. 11 shows the case
where the top of the glass substrate 11 is not in contact, and FIG. 12 shows the case where the
top of the glass substrate 11 is in contact. Since the glass substrate 11 is provided between the
interdigital electrodes T1 and R11, it can be seen that good response characteristics with no
electromagnetic direct waves and few spurious signals are exhibited. Therefore, signal processing
can be facilitated.
[0045]
FIG. 13 is a characteristic diagram showing a spectrum of oscillation in the delay line oscillator
shown in FIG. fo denotes a fundamental wave and is 3.951 MHz. Since the touch panel unit 1 is
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designed in the primary mode, stable oscillation is obtained without being affected by the other
modes. Further, since the surface wave propagates with almost no spread, it can be easily
oscillated without being affected by other waves.
[0046]
FIG. 14 is a characteristic diagram showing the velocity dispersion curve of the surface acoustic
wave propagating through the glass substrate 11 of the touch panel portion 1. The product (kd)
or elasticity of the wave number k of the surface acoustic wave and the thickness d of the
piezoelectric ceramic thin plate 13 is shown. It is a figure which shows the phase velocity of each
mode with respect to the ratio (d / lambda) with respect to wavelength (lambda) of a surface
wave. However, in the piezoelectric ceramic thin plate 13, the plate surface (the glass side plate
surface) of the piezoelectric ceramic thin plate 13 in contact with the glass substrate 11 is in the
electrically open state and the plate surface of the one contacting the other air (air One in which
the side plate surface is electrically shorted and the other in which the glass side plate surface of
the piezoelectric ceramic thin plate 13 and the air side plate surface are electrically shorted. In
the present embodiment, the plate surface of the piezoelectric ceramic thin plate 13 is covered
with a metal thin film to electrically short the plate surface. In the figure, "short" indicates a short
circuit state and "open" indicates an open state. The surface acoustic wave has a plurality of
modes. The zero-order mode is the basic Rayleigh wave, and the zero-order mode corresponds to
the Rayleigh wave velocity of the glass substrate 11 when the kd value is zero, and converges to
the Rayleigh wave velocity of the piezoelectric ceramic thin plate 13 as the kd value increases.
ing. In the first and higher modes, a cutoff frequency exists, and converges to the shear wave
velocity of the glass substrate 11 when the kd value is the respective minimum. In the figure, ○
indicates the actual measurement value.
[0047]
FIG. 15 is a characteristic diagram showing velocity dispersion curves of surface acoustic waves
propagating through the glass substrate 11 of the touch panel portion 1, and showing phase
velocity in each mode with respect to kd value or d / λ value. However, in the piezoelectric
ceramic thin plate 13, the glass side plate surface of the piezoelectric ceramic thin plate 13 and
the air side plate surface are both electrically open, and the glass side plate surface of the
piezoelectric ceramic thin plate 13 is electrically shorted. The air side plate surface used the
thing in an electrically open state. In the zero-order mode, when the fd value is zero, it matches
the Rayleigh wave velocity of the glass substrate 11, and converges to the Rayleigh wave velocity
of the piezoelectric ceramic thin plate 13 as the kd value increases. In the first and higher modes,
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a cutoff frequency exists, and converges to the shear wave velocity of the glass substrate 11
when the kd value is the respective minimum. In the figure, ○ marks indicate actual values.
[0048]
FIG. 16 is a characteristic diagram showing the relationship between the effective
electromechanical coupling coefficient k2 and the kd value calculated from the phase velocity
difference under two different electrical boundary conditions of the piezoelectric ceramic thin
plate 13. In FIG. However, as the piezoelectric ceramic thin plate 13, an interdigital transducer
(IDT) is provided on the glass side plate surface of the piezoelectric ceramic thin plate 13 and the
air side plate surface is electrically shorted. The higher order mode k2 exhibits a larger value
than the zero order mode. In particular, in the first-order mode, the maximum value of k2 =
17.7% is shown at kd = 1.8.
[0049]
FIG. 17 is a characteristic diagram showing the relationship between the effective
electromechanical coupling coefficient k2 and the kd value calculated from the phase velocity
difference under two different electrical boundary conditions of the piezoelectric ceramic thin
plate 13. In FIG. However, as the piezoelectric ceramic thin plate 13, one in which a interdigital
electrode is provided on the glass side plate surface of the piezoelectric ceramic thin plate 13 and
the air side plate surface is electrically opened is used. The higher order mode k2 exhibits a
larger value than the zero order mode.
[0050]
FIG. 18 is a characteristic diagram showing the relationship between the effective
electromechanical coupling coefficient k2 and the kd value calculated from the phase velocity
difference under two different electrical boundary conditions of the piezoelectric ceramic thin
plate 13. In FIG. However, as the piezoelectric ceramic thin plate 13, one in which the glass side
plate surface of the piezoelectric ceramic thin plate 13 is electrically shorted and the interdigital
electrode is provided on the air side plate surface is used.
[0051]
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22
FIG. 19 is a characteristic diagram showing the relationship between the effective
electromechanical coupling coefficient k2 and the kd value calculated from the phase velocity
difference under two different electrical boundary conditions of the piezoelectric ceramic thin
plate 13. However, as the piezoelectric ceramic thin plate 13, the one in which the glass side
plate surface of the piezoelectric ceramic thin plate 13 is electrically opened and the interdigital
electrode is provided on the air side plate surface is used.
[0052]
From FIGS. 14-19, it can be seen that in the first or higher mode, k2 exhibits a maximum value
when the velocity of the surface acoustic wave propagating through the touch panel portion 1 is
equal to the velocity of the surface acoustic wave propagating through the glass substrate 11
alone.
[0053]
16-19, in the structure in which the interdigital electrode is provided on the glass side plate
surface of the piezoelectric ceramic thin plate 13 and the air side plate surface is electrically
short-circuited, the electrical energy applied to the interdigital electrode is converted to surface
acoustic wave. It can be seen that the degree increases.
[0054]
In the case of exciting a surface acoustic wave on the glass substrate 11 of the touch panel
portion 1, it is necessary to take into consideration, for example, reflection caused by a mismatch
of acoustic impedance or the like at the interface between the piezoelectric ceramic thin plate 13
and the glass substrate 11.
As a means to minimize the reflection coefficient, the touch panel unit 1 is designed so that the
surface wave velocity in the touch panel unit 1 and the surface wave velocity of the glass
substrate 11 alone become equal. Designing the touch panel unit 1 so that the ratio (d / λ) of
the thickness d of the panel 1 becomes small can be mentioned.
When the d value is constant, the secondary mode is more effective than the tertiary mode, and
the primary mode is more effective than the secondary mode.
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[0055]
According to the ultrasonic learning apparatus of the present invention, the plate surface Z1 of
the substrate is adopted by adopting a structure for inputting an electric signal from the
interdigital electrodes Pi (i = 1, 2,..., N). Can excite surface acoustic waves. Moreover, the surface
acoustic wave can be excited efficiently without applying high voltage with low power
consumption. The interdigital electrodes Qi-1 and Qi-2 are used for output, and the interdigital
electrodes Qi-1 and Qi-2 are arranged so that the directivity axes of transmission and reception
of surface acoustic waves are common to the interdigital electrode Pi. By adopting such a
structure, the surface acoustic wave excited on the plate surface Z1 can be efficiently output as
an electric signal. Excitation is made on the surface Z1 by contacting the surface acoustic wave
propagation path on the surface Z1 (ie, between the interdigital electrodes Pi and Qi-1 and
between Pi and Qi-2) with the pen tip of the input pen Since the surface acoustic wave that is
being annihilated or attenuated, the electrical signals output to the interdigital electrodes Qi-1
and Qi-2 are also annihilated or attenuated. At this time, it is possible to identify the contact
portion touched by the pen point by identifying the interdigital electrode from which the output
electric signal disappears or attenuates among the interdigital electrodes Qi-1 and Qi-2. Thus, the
ultrasonic learning apparatus of the present invention has a short response time and good
sensitivity. The pen point needs to be made of a material that is softer than the substrate and
easily absorbs ultrasonic waves, and a human finger or the like also has that feature.
[0056]
By adopting a structure for inputting an electrical signal of at least one frequency substantially
corresponding to the electrode period length of interdigital electrode Pi to interdigital electrode
Pi, at least plate having a wavelength approximately equal to the electrode period length on plate
surface Z1 One type of surface acoustic wave can be excited. Further, the surface acoustic wave
excited on the plate surface Z1 can be output as an electric signal from the interdigital electrodes
Qi-1 and Qi-2 in accordance with the wavelength.
[0057]
A structure in which at least two ultrasonic wave transmitting and receiving means are provided
on the plate surface Z1 and propagation paths of surface acoustic waves between the interdigital
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electrode Pi and the interdigital electrode group Qi in one ultrasonic wave transmitting and
receiving means By adopting a structure in which the surface acoustic wave propagation paths
between the interdigital electrode Pi and the interdigital electrode group Qi in another ultrasonic
wave transmitting and receiving means are orthogonal to each other, the contact portion in the
plate surface Z1 is further It can be identified delicately. This can be more finely specified as the
number of ultrasonic wave transmitting and receiving means increases.
[0058]
By connecting the output ends of the interdigital electrodes Qi-1 to each other electrically at the
connection point N1, and connecting the respective output ends of the interdigital electrodes Qi2 to each other at the connection point N2, the plate surface is obtained. The contact portion at
Z1 can be detected from the magnitude of the electrical signal appearing at the connection point
N1 or the connection point N2. As a means for inputting an electrical signal to the interdigital
transducer Pi, N switches Si (i = 1, 2,..., N) each having an output end connected to the input of
the interdigital transducer Pi are provided. An electric signal can be sequentially input to the
interdigital electrode Pi by adopting a structure in which Si is sequentially electrically
disconnected at a predetermined cycle. Therefore, in the propagation path of the surface acoustic
wave on the plate surface Z1, for example, when contact is made between the interdigital
electrodes P1 and Q1-1, only when an electric signal is inputted to the interdigital electrode P1.
The delayed electrical signal output to the connection point N1 is attenuated or extinguished. In
this way, it is possible to clearly specify the contact position.
[0059]
By adopting a structure in which respective input ends of switches Si are electrically connected
to each other at connection point NS, and connection point N1 is electrically connected to
connection point NS via an amplifier, interdigital electrodes Pi to Qi- An oscillator Hi (i = 1, 2,...,
N) having as a delay element a propagation path Di (i = 1, 2,..., N) of a surface acoustic wave
consisting of a plate surface Z1 between 1 and can do. The signal loop of the oscillator Hi
comprises an interdigital electrode Pi, a propagation path Di, an interdigital electrode Qi-1, and
an amplifier. In this manner, since the circuit configuration is simplified, the reduction in size and
weight of the device is further promoted, and furthermore, low power consumption and low
voltage driving can be achieved.
[0060]
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25
By adopting a structure having at least two electrode period lengths L1 and L2 respectively as
interdigital electrodes Pi, Qi-1 and Qi-2, the interdigital electrode Pi has a frequency substantially
corresponding to the electrode period L1 or L2 An electrical signal can be input. Therefore, it is
possible to excite the surface acoustic wave having a wavelength substantially equal to the
electrode period length L1 or L2 on the plate surface Z1. In addition, surface acoustic waves
having a wavelength substantially equal to the electrode period L1 or L2 excited on the plate
surface Z1 can be output as an electrical signal from the interdigital electrodes Qi-1 and Qi-2. By
arranging the interdigital electrode Pi and the interdigital electrode group Qi in the ultrasonic
wave transmitting / receiving means such that the electrode fingers having a smaller electrode
cycle length are inside each other, that is, the interelectrode distance is reduced, The attenuation
of the surface acoustic wave excited to Z1 can be suppressed.
[0061]
As an information input means, a means for bringing the pen tip into contact with the surface Z1
and inputting information is included. Moreover, the structure which displays information on a
display screen by contact is employ | adopted. Information on the display screen can be viewed
as it is via the plate surface Z1. Moreover, the transparency of the display screen seen through
the plate surface Z1 is excellent. This is nothing but a structure in which the display and the
keyboard are integrated. Therefore, while the size and weight reduction and thickness reduction
of the device are further promoted, the screen is clear, and moreover, even a beginner can easily
operate.
[0062]
A structure is adopted in which information corresponding to the position of the contact portion
is displayed on the display screen for a predetermined time. However, the information is
information to be input from now, or information that is already stored and output to the display
screen based on the position of the contact portion. Therefore, when inputting information such
as characters, the characters can be displayed on the display screen by drawing characters and
the like on the surface Z1 with the pen tip. In this manner, by directly writing characters,
symbols, and other information on the surface Z1, not only the information can be input, but also
it can be displayed as an image on the display screen. Moreover, it is also possible to output
information already stored on the display screen by contacting a predetermined portion of the
plate surface Z1. Furthermore, a structure is adopted in which another learning information is
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displayed on the display screen according to the learning information displayed on the display
screen. In this way, interactive learning becomes possible. For example, a series of operations
such as first displaying a problem on a screen, secondly writing in the answer of the problem on
a screen, and thirdly displaying a model answer on a screen can be performed on the same
screen.
[0063]
The information processing means includes means for specifying a contact portion on the plate
surface Z1 contacted by the pen point, and input information detection means for detecting
information input by the information input means based on the position of the contact portion. .
In addition, the information processing means includes an information storage means. By
adopting a structure in which a table in which the position on the surface Z1 is an address and
the information associated with the position is stored as the information storage means is stored,
the position of the contact portion is input as an address. Therefore, stored data can be read out
from the address. Also, by adopting a structure in which patterns such as characters and symbols
are stored in advance as information storage means, a locus formed by the movement of the
position of the portion to be touched is input, and the locus is compared with the pattern. And
the information indicated by the locus is recognized. Therefore, information such as characters
drawn on the surface Z1 can be input.
[0064]
By adopting a structure in which information is displayed in at least two colors as the display
screen, and by adopting a structure in which the frequency of the electric signal input to the
interdigital transducer Pi corresponds to the color of the display screen By switching the
frequency to the location, it becomes possible to input separately color-coded information. That
is, it is possible to input color-coded information for each frequency by contacting the portion on
the plate surface Z1 for each frequency. Therefore, it also increases the amount of input
information.
[0065]
By using a translucent piezoelectric ceramic such as La-doped zircon-lead titanate (PLZT) as a
substrate, and adopting a structure in which the direction of the polarization axis of the
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piezoelectric ceramic is parallel to the thickness direction. Surface acoustic waves can be
efficiently excited on the substrate. At this time, the interdigital electrode Pi and the interdigital
electrode group Qi are provided directly on the substrate. Further, by adopting a substantially
transparent structure as the piezoelectric ceramic, the information appearing on the display
screen can be viewed from above the plate surface Z1. In order to propagate the surface acoustic
wave to the surface Z1 of the substrate made of piezoelectric ceramic, it is desirable that the
thickness of the substrate is at least three times the electrode period length of the interdigital
electrodes Pi, Qi-1 and Qi-2. In the case where the thickness of the substrate is smaller than the
electrode cycle length and the thickness is thin, Lamb waves propagate, but if there is a mode
that can function as a touch panel, it is possible to use Lamb waves. As the substrate, in addition
to the piezoelectric ceramic, single crystals such as LiNbO3 and LiTaO3 can be considered.
Although these single crystals are promising as substrates because they are transparent and
piezoelectric, they have anisotropy as crystals, so they need to be devised at the design stage
including the electromechanical coupling coefficient. Not only that, but it may require extra
electronic circuitry. Among piezoelectric ceramics, PLZT is promising as a substrate because it is
transparent and is excellent in processability and durability. Propagation path of surface acoustic
wave between interdigital transducer electrode Pi and interdigital transducer group Qi in one
ultrasonic wave transmitting and receiving means by utilizing isotropy in the plane of plate
surface Z1 of the substrate made of PLZT And the propagation path of the surface acoustic wave
between the interdigital transducer Pi and the interdigital transducer group Qi in another
ultrasonic wave transmitting and receiving means are orthogonal to each other. The level of the
electrical signal output to one interdigital transducer group Qi can be made substantially the
same. Therefore, the circuit configuration is simplified and not only the reduction in size and
weight of the device can be promoted, but also the output signal can always be made uniform, so
that the signal processing becomes accurate and the sensitivity is improved. Furthermore, since
the resolution is also increased, the amount of input information can be increased.
[0066]
A non-piezoelectric body is adopted as a substrate, and an ultrasonic wave transmitting /
receiving means is constituted by ultrasonic devices A and B, and an ultrasonic device A is
provided with an interdigital electrode Pi on a piezoelectric thin plate a. Since the interdigital
transducer group Qi is provided on the piezoelectric thin plate b, it is possible to excite the
surface acoustic wave of the first mode or the second or higher mode to the plate surface Z1 of
the substrate in a portion contacting the interdigital electrode Pi. . At this time, by adopting a
structure in which the phase velocity of the surface acoustic wave is substantially equal to the
propagation velocity of the surface acoustic wave in the single substrate, the electrical energy
applied from the interdigital electrode Pi is converted into the surface acoustic wave. Not only it
is possible to increase the degree, it is possible to remove the reflection and the like caused by
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the acoustic impedance mismatch and the like at the interface between the piezoelectric thin
plate and the substrate. In this manner, the surface acoustic wave can be efficiently excited on
the surface Z1 of the substrate with low power consumption and without applying a high voltage.
In addition, the area of the substrate can be made relatively large, which enables a wide range of
applications. The piezoelectric thin plates a and b are provided on the plate surface Z1.
[0067]
The thickness of each of the piezoelectric thin plates a and b in the ultrasonic devices A and B is
made equal to or less than the electrode period length of the interdigital electrode, and the
electrode period length of the interdigital electrode is the surface acoustic wave of the first mode
or second or higher mode By adopting a structure approximately equal to the wavelength, it is
possible not only to increase the degree to which the electrical energy applied from the
interdigital electrode is converted to surface acoustic waves, but also between the piezoelectric
thin plate and the nonpiezoelectric substrate. It is possible to remove reflections and the like
caused by acoustic impedance mismatch and the like at the interface. The smaller the ratio (d /
λ) of the thickness d of the piezoelectric thin plate to the electrode period length of the
interdigital transducer, that is, the wavelength λ of the surface acoustic wave, the larger the
effect.
[0068]
By employing a piezoelectric ceramic, PVDF or other polymeric piezoelectric film as the
piezoelectric thin plate, it is possible to excite the surface acoustic wave of the primary mode or
the secondary or higher mode to the substrate efficiently. By adopting a structure in which the
direction of the polarization axis coincides with the thickness direction, the piezoelectric ceramic
can excite the surface acoustic wave of the first mode or the second or higher mode efficiently to
the substrate.
[0069]
By adopting a structure in which the interdigital transducer is provided at the interface between
the non-piezoelectric substrate and the piezoelectric thin plate, the electrical energy applied to
the interdigital transducer can be efficiently converted to surface acoustic waves.
[0070]
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In this way, the ultrasonic learning apparatus according to the present invention receives
processing instructions by touching the surface Z1 with the input pen, recognizes handwriting,
recognizes characters such as kana-kanji conversion, draws figures and pictures, draws lines,
inserts and inserts. Operations such as deletion can be easily performed by beginners without a
manual.
In addition, it is also possible to connect an optional external keyboard, and keyboard input is
also possible. It can also handle communication functions, and can also connect a printer, an
external CRT, etc. Therefore, the ultrasonic learning apparatus according to the present invention
is not limited to the case where the problem is solved by the individual utilizing the interactive
function, but learning such as having a third party reply an exemplary reply using the
communication function A wide range of applications as devices are possible.
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