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JPH11191899

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DESCRIPTION JPH11191899
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
electro-mechanical-acoustic conversion device used for generating ringing tone or ringing
vibration of a portable terminal such as a portable telephone, pager or PHS (Personal Handy
Phone Set). is there.
[0002]
2. Description of the Related Art Conventionally, in a portable terminal device such as a portable
telephone, pager, PHS (Personal Handy Phone Set) or the like, an electro-mechanical-acoustic
transducer is attached in its main body, and an electrical signal generator is connected. It has
been used as a means of selectively generating bell sound and vibration and notifying of an
incoming call.
[0003]
A conventional electro-mechanical-acoustic transducer will be described with reference to FIGS.
FIG. 10 is a block circuit diagram of the concept of the conventional electro-mechanical-acoustic
transducer, FIG. 11 is a side cross-sectional view of the electro-mechanical-acoustic transducer
which is the main part, and FIG. FIG. 13 is an electrical impedance frequency characteristic
diagram of the acoustic transducer, and FIG. 13 is a perspective view of a mobile phone equipped
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with the same device.
[0004]
First, the electro-mechanical-acoustic transducer which is the main part will be described. 1 is a
support member having openings at both ends, and 2 is mounted to one opening of the support
member 1 via the suspension 3 A movable portion comprising a yoke 2a, a magnet 2b and a
plate 2c, and 4 is a vibration coupled to the voice coil 5 inserted into the magnetic gap 2d of the
movable portion 2 and attached to the other opening of the support member 1 It is a board.
[0005]
The operation of the electro-mechanical-acoustic transducer will be described. The movable part
2 including the suspension 3 constitutes a mechanical resonance system by its mass and the
stiffness of the suspension 3 and has an inherent resonance frequency.
Further, the diaphragm 4 to which the voice coil 5 is coupled also has an inherent resonance
frequency generated by its own stiffness and mass.
[0006]
Now, when an electric signal is applied to the voice coil 5, an action / reaction force is generated
between the voice coil 5 and the movable portion 2. When the electric signal matches the
inherent resonance frequency of the movable portion 2, the movable portion 2 vibrates to a large
extent, and the vibration force is transmitted to the support member 1 via the suspension 3.
Further, when the electric signal matches the inherent resonance frequency of the diaphragm 4
to which the voice coil 5 is coupled, the diaphragm 4 is vibrated to generate a buzzer sound.
[0007]
As shown in the electrical impedance frequency characteristic diagram of FIG. 12, the natural
resonance frequency f01 of the movable portion 2 is around 100 Hz, and the natural resonance
frequency f01 of the diaphragm 4 is different from around 2 KHz. The following convenience can
be obtained by generating the following frequency.
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[0008]
That is, as shown in FIGS. 10 and 13, the electro-mechanical-acoustic device A incorporated in
the mobile telephone 6 generates a signal of a predetermined frequency in the electric signal
generator 7 according to an instruction from the main body of the mobile telephone 6. This
electric signal is input to the electro-mechanical-acoustic converter A to vibrate the diaphragm 4
to produce sound, vibrate the movable portion 2 to vibrate the main body of the mobile phone 6,
and the user is notified by the vibration by the vibration. To convey the incoming call.
[0009]
If one of the eigen resonant frequencies of the movable portion 2 or the diaphragm 4 is selected
as the signal of the predetermined frequency, resonance occurs at either of them and a large
vibration or sound is obtained, and if both are selected, the vibration is generated. The big thing
of pronunciation is obtained.
[0010]
Although the above-described conventional electro-mechanical-acoustic transducer A has been
described as vibration and sound generation, there are also only vibrations or sound generation,
and the electro-mechanical-acoustic transducer in the embodiments of the invention described
below is also used. It is similar.
[0011]
As is apparent from the above description, in order to cause the electro-mechanical-acoustic
transducer A to generate a large sound or vibration, a resonance frequency matching an inherent
frequency is used as the electrical signal generator 7. However, the characteristic frequency
changes due to changes in environmental conditions such as the ambient temperature of the
electro-mechanical-acoustic transducer A, and the oscillation frequency on the side of the
electrical signal generator 7 slightly changes. And the output of vibration decreases and becomes
unstable.
[0012]
The present invention solves the above-mentioned problems and provides an electro-mechanicalacoustic conversion device capable of obtaining a stable oscillation output.
[0013]
SUMMARY OF THE INVENTION In order to solve the above problems, an electro-mechanicalacoustic transducer according to the present invention has at least one resonance frequency, and
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electro-mechanical which converts an amplified signal into vibration or sound. A frequency
detection means for detecting a frequency signal at a resonance frequency of the electromechanical-acoustic conversion means and outputting the signal to an amplification means by a
bridge circuit in which the acoustic conversion means and the electrical impedance of the
electro-mechanical-acoustic conversion means are one element And noise generated by the
electric circuit including the amplification means or the frequency detection means and the
output of the frequency detection means are amplified and output as the amplification signal to
the electro-mechanical-acoustic conversion means. Because of the configuration, the fluctuation
of the resonance frequency is always detected by the frequency detection means, and an
extremely stable oscillation output can be efficiently obtained.
[0014]
The electro-mechanical-acoustic conversion device of the present invention has electromechanical-acoustic conversion means having at least one resonance frequency and converts an
amplified signal into vibration or sound, and the electro-mechanical-acoustic conversion means
described above. A bridge circuit having an electrical impedance as one element detects a
frequency signal at a resonance frequency of the electro-mechanical-acoustic conversion means
and outputs the signal to an amplification means, and a resonant frequency of the electromechanical-acoustic conversion means Since the oscillation means for oscillating the electric
signal in the frequency band and the amplification means for amplifying the electric signal and
outputting the electric signal to the electro-mechanical-acoustic conversion means as the
amplification signal, fluctuation of the resonance frequency is always detected A highly stable
oscillation output can be efficiently obtained by detecting by means.
[0015]
Further, the electro-mechanical-acoustic transducer of the present invention has an electromechanical-acoustic transducer having at least two resonance frequencies and converting the
first or second electrical signal into vibration or sound, and the above-mentioned electricity- First
oscillation means for oscillating the first electrical signal in a frequency band including the
resonance frequency of the mechanical-acoustic transducer and outputting the first electrical
signal to the electrical-mechanical-acoustic transducer; and the electro-mechanical-acoustic
conversion means A second oscillation unit that oscillates the second electrical signal in a
frequency band including a resonance frequency and outputs the second electrical signal to the
electro-mechanical-acoustic transducer; and one element of the electrical impedance of the
electro-mechanical-acoustic transducer Frequency detection means for detecting the frequency
of the preset output level of the electro-mechanical-acoustic transducer as a resonant frequency
by a bridge circuit, and the detected frequency based on the information detected by the
frequency detection means Since it comprises the control means for controlling the second
oscillation means so as to vibrate and output it to the electro-mechanical-acoustic transducer, it is
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very easy to find the resonance frequency and operate at this resonance frequency. It can be
done very easily and quickly.
[0016]
The electro-mechanical-acoustic transducer of the present invention has an electro-mechanicalacoustic transducer, which has at least one resonance frequency and transforms an electrical
signal into vibration or sound, and the electro-mechanical-acoustic transducer. A bridge circuit
which oscillates a frequency signal of a frequency band including a resonance frequency and
outputs the electric signal to the electric-machine-acoustic converter, and an electric impedance
of the electric-machine-acoustic conversion means as one element And frequency detection
means for detecting the frequency of the preset output level of the electro-mechanical-acoustic
transducer as a resonance frequency, and oscillating the oscillation means at the frequency
detected as the resonance frequency by the frequency detection means. Oscillation of a
frequency signal of a frequency band including the resonance frequency of the electromechanical-acoustic transducer by time division and detection as a resonance frequency by the
frequency detection means Control means for controlling the oscillating means so that the
oscillating frequency is oscillated by the oscillating means, the number of oscillating means is
reduced to one, and the shift of the resonant frequency due to environmental changes etc. is
constantly monitored It is possible to correct and maintain a stable resonance state.
Furthermore, the frequency detection means for detecting the resonance frequency in the bridge
circuit can cancel the change by using a circuit element having a resistance temperature
characteristic substantially equal to the resistance temperature characteristic of the
electromechanical-acoustic transducer in the bridge circuit. Since it is possible, it is possible to
maintain a stable resonance state.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below with reference to FIGS.
[0018]
(First Embodiment) FIG. 1 is a block circuit diagram of a main part of a portable terminal using
the electro-mechanical-acoustic converter according to a first embodiment of the present
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invention.
According to the figure, 10 is an oscillator, 11 is an amplifier which is an amplifying means to
which the output of the oscillator 10 is inputted, and 12 is a conventional electro-mechanicalacoustic transducer which is an electro-mechanical-acoustic transducer. An electro-mechanicalacoustic transducer having the same configuration as A, 13 is a frequency detector that detects
an output at resonance of the electro-mechanical-acoustic transducer 12 and outputs the output
to the amplifier 11; an operational amplifier 14 and a bridge The circuit comprises a circuit 15,
Z2, Z3 and Z4 are load impedances of circuit elements constituting a bridge, Z1 shows an
electrical impedance of a voice coil of the electro-mechanical-acoustic transducer 12, and Z1 , Z2,
Z3 and Z4 constitute a bridge circuit 15, and for frequency signals other than the resonance
frequency, the output voltage E2 is set to an equilibrium state where the output is small
(preferably 0) with respect to the input voltage E1. ing.
The oscillator 10 oscillates a frequency in a frequency band including at least one of the natural
frequency of the electro-mechanical-acoustic transducer 12 (for example, f01 or f02 described in
FIG. 12 of the prior art). However, it may be an electrical signal generation source, and even if its
output voltage level is amplified by the amplifier 11, it controls the oscillation output to such an
extent that substantial sound generation and vibration do not occur by driving the abovementioned electro-mechanical-acoustic converter 12. It is done.
[0019]
Next, the operation will be described.
When an external signal C described later is generated, the signal C turns on the switch SW1
which is normally in the OFF state.
When SW1 is turned on, the output signal of the oscillator 10 is sent to the amplifier 11, this
output signal is amplified and output by the amplifier 11, and is input to the electro-mechanicalacoustic transducer 12.
When the frequency component at the resonance point f01 or f02 is input to the electromechanical-acoustic transducer 12 by the oscillation output from the oscillator 10 amplified by
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the amplifier 11, the electrical impedance Z1 of the electro-mechanical-acoustic transducer 12 is
abruptly As it rises, the balance of the bridge circuit 15 at this resonance frequency is lost, the
output from the operational amplifier 14 increases, and this output is input to the amplifier 11.
This change is detected by the frequency detector 13 and further amplified by feedback to the
amplifier 11, and by repeating this, either or both of vibration or sound generation by the
electro-mechanical-acoustic transducer 12 is self-excited It will be done.
[0020]
In the above embodiment, when there is a change in the above-mentioned natural frequency of
the electro-mechanical-acoustic transducer 12 due to the environmental change in which the
electro-mechanical-acoustic transducer 12 is placed, the electro-mechanical-acoustic transducer
Although the output for driving 12 is reduced to suppress oscillations and oscillations, since
oscillation from the oscillator 10 is continuously performed, the frequency detector 13 detects
the resonance point again, and the new resonance point is detected. The vibration and sound
generation of the electro-mechanical-acoustic transducer 12 are to be performed in a selfexcitation manner.
[0021]
Here, the bridge circuit 15 constituting the frequency detector 13 for detecting the resonance
frequency of the electro-mechanical-acoustic transducer 12 will be described in more detail.
[0022]
The input voltage E1 is applied to the junction point G of Z1 and Z2 and the junction point B of
Z3 and Z4 in the bridge circuit 15 configured by the impedances Z1, Z2, Z3 and Z4.
The output voltage E2 is taken out from the junction point C of Z1 and Z3 and the junction point
D of Z2 and Z4.
The relationship between the input voltage E1 and the output voltage E2 at this time is expressed
by the following equation.
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[0023]
E2 = {[Z1 / (Z1 + Z2)] − [Z3 / (Z3 + Z4)]} E1 Here, assuming that Z1 / Z2 = Z3 / Z4, the bridge
circuit 15 is in an equilibrium state, and the level of the output voltage E2 is 0 Become.
Assuming that Z2, Z3 and Z4 are fixed resistors, for example, the impedance does not have
frequency characteristics and has a constant resistance value in all frequency bands.
On the other hand, the electrical impedance Z1 of the electro-mechanical-acoustic converter 12 is
set to a value close to the DC resistance value of the voice coil 5 described in FIG. If the bridge
circuit 15 is in a balanced state, the value of Z1 increases at the resonance point of the electromechanical-acoustic transducer 12 where the electrical impedance is greatly increased, and the
balance condition of the bridge circuit 15 is not satisfied. It can be detected as E2.
That is, the bridge circuit 15 detects the resonance frequency of the electro-mechanical-acoustic
converter 12. For example, assuming that the direct current resistance of the voice coil 5 is 8 Ω,
Z2 = 0.5 Ω, Z3 = 8000 Ω, Z4 = 500 Ω. It is set as satisfying the equilibrium condition of
resistance value / Z2 = Z3 / Z4 of Z1. Note that Z2 connected in series to the electro-mechanicalacoustic transducer 12 has a smaller Z2 than Z1 in order to reduce the power loss due to this
element, that is, the impedance ratio, resistance value of Z1, / Z2 of Z1, or Z3. It is desirable that
/ Z4 be 10 or more. Similarly, the series connection of Z3 and Z4 connected in parallel to the
series connection of Z1 and Z2 has an input of 8000 Ω which is 1000 times that of Z1 = 8 Ω as
shown by the above numerical value, that is, Z3 >> Z1 It is desirable to have most of the current
flow through the electro-mechanical-acoustic transducer 12 to prevent the generation of large
power losses due to frequency detection, a circuit operation that is not directly related to the
main purpose of vibration and sound generation.
[0024]
The electrical impedance Z1 of the electro-mechanical-acoustic transducer 12 is the electrical
impedance of the voice coil, and the material of the coil used for this type of electro-mechanicalacoustic transducer 12 is usually copper or aluminum. When the temperature of the environment
in which the electro-mechanical-acoustic transducer 12 is used changes to a low temperature or
a high temperature, the resistance value of the coil of copper or aluminum changes as the
temperature changes. The bridge circuit 15 that configures the frequency detector 13 balances
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Z1, Z2, Z3, and Z4 in the initial setting of the circuit, but when the temperature of the operating
environment changes from the temperature at the initial setting, the resistance value of Z1
Changes to break the equilibrium condition of the bridge circuit 15, and the operation of the
frequency detector 13 becomes unstable. In order to prevent this, it is preferable that the
impedance ratio Z1 resistance value / Z2 and Z3 / Z4 do not change due to temperature change.
If Z3 and Z4 are selected as the fixed resistance as described above, as a fixed resistance, Z3 / Z4
does not change significantly. Further, if the materials used for the resistors are the same, the
ratio of change in resistance value with temperature change is equal, so that the ratio of Z3 / Z4
can be made substantially constant with respect to temperature change. Similarly, if an element
having the same temperature characteristic as that of the coil of the electro-mechanical-acoustic
transducer 12 is used as Z2, it is possible to make the ratio of resistance value / Z2 of Z1
constant regardless of temperature. Become. The element used as Z2 for this purpose is a
temperature sensitive resistor having the same temperature characteristics as the coil (copper or
aluminum etc.) of the electro-mechanical-acoustic converter 12, or a high frequency whose
inductance component can be ignored in the audio band of 20 kHz or less. Coils and the like.
[0025]
With the above configuration, the electro-mechanical-acoustic transducer can be obtained that
can always produce stable sounding and vibration of the electro-mechanical-acoustic transducer
12 even when the temperature of the use environment changes.
[0026]
(Embodiment 2) FIG. 2 is a block circuit diagram of a main part of a portable terminal using the
electro-mechanical-acoustic converter according to Embodiment 2 of the present invention.
According to the figure, 37 is an antenna, 36 is a reception signal processing unit, 38 is a
receiver as a small speaker, 10 is an oscillator, 11 is an amplifier as amplification means to which
the output of the oscillator 10 is input, 12 Is an electro-mechanical-acoustic transducer having
the same configuration as the conventional electro-mechanical-acoustic transducer A, which is an
electro-mechanical-acoustic transducer, and 13 is an output at the time of resonance of the
electro-mechanical-acoustic transducer 12 Is a frequency detector that outputs the signal to the
amplifier 11, and the temperature characteristic substantially equal to the temperature
characteristic of the resistance of the voice coil of the electro-mechanical-acoustic transducer 12
as the component circuit element described in the first embodiment. And a bridge circuit
comprising a temperature sensitive resistor. The oscillator 10 oscillates a frequency in a
frequency band including at least one of the eigenfrequency of the electro-mechanical-acoustic
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transducer 12 (the eigenfrequency is described in the prior art and thus the description is
omitted). It may be an electrical signal generation source, and even if its output voltage level is
amplified by the amplifier 11, it does not generate substantial sound or vibration by driving the
electro-mechanical-acoustic converter 12. It is controlled to the oscillation output.
[0027]
Next, the operation will be described. The antenna 37 receives an incoming signal sent from the
transmitter of the mobile phone. The incoming signal includes a received signal indicating an
incoming call and a received sound signal which is the speech of the transmitter. This incoming
signal is signal-processed in the received signal processing unit 36, and first, a signal C is
generated in response to the received signal for notifying the receiver of the incoming call. When
the receiver knows the incoming call and enables the mobile phone to receive, the reception
signal processing unit 36 stops the signal C, sends a reception sound signal to the receiver 38,
and the receiver 38 generates a reception sound. When the signal C is generated, the switch C1
in the normally OFF state is turned on by the signal C. When SW1 is turned on, the output signal
of the oscillator 10 is sent to the amplifier 11, this output signal is amplified and output by the
amplifier 11, and is input to the electro-mechanical-acoustic transducer 12.
[0028]
At this time, at the natural frequency (f01 or f02) of the electro-mechanical-acoustic transducer
12, the electrical impedance is rapidly increased due to the resonance phenomenon. This change
is detected by the frequency detector 13 and is further amplified by feeding it back to the
amplifier 11. As a result, as described above, the output of the electro-mechanical-acoustic
transducer 12 is increased in a self-excited manner to cause vibration or sound generation.
[0029]
Reference numeral 16 denotes a limiter for limiting the input from the frequency detector 13 to
the amplifier 11 to make the input voltage of the electro-mechanical-acoustic converter 12
constant, but the limiter 16 may not necessarily be necessary. .
[0030]
As described above, in the electro-mechanical-acoustic conversion device of the above
embodiment, the signal of the frequency band including the resonant frequency which is always
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the natural frequency of the electro-mechanical-acoustic transducer is oscillated by the oscillator
and amplified by the amplifier. The vibration of the electro-mechanical-acoustic transducer is
automatically generated or generated, and the variation of the resonant frequency of the electromechanical-acoustic transducer is constantly made to the change of the use environmental
condition including the temperature change. It is detected by a detector and is further tracked to
efficiently obtain an extremely stable oscillation output.
[0031]
Third Embodiment The third embodiment of the present invention will be described with
reference to the block circuit diagram of FIG.
In the description, the same parts as in the first embodiment are given the same reference
numerals and the description thereof is omitted.
That is, the difference from the first embodiment in the present embodiment lies in the
elimination of the above-described oscillator, and the thermal noise etc. which the electric circuit
including the amplifier 11 and the frequency detector 13 has in its own circuit instead of the
oscillator. Noise is used. As in the first embodiment, the frequency detector 13 is formed of a
bridge circuit having a temperature sensitive resistor in its circuit element.
[0032]
Noise such as thermal noise is composed of frequency components of a wide range of band
frequencies and is generally at a low level compared to signal components. When the SW 1 is
turned on by the signal C, this noise is amplified by the amplifier 11 and input to the electromechanical-acoustic transducer 12. The resonance frequency is detected by the frequency
detector 13 and self-excited amplification is performed as described in the first embodiment to
vibrate or generate the electro-mechanical-acoustic transducer 12. As a result, the oscillator can
be eliminated to contribute to simplification of the device, and miniaturization can be achieved. In
addition, stable output against temperature change can be obtained.
[0033]
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Fourth Embodiment A fourth embodiment of the present invention will be described with
reference to the block circuit diagram of FIG. Only differences with the third embodiment will be
described.
[0034]
The difference from the third embodiment is that the low pass filter 19 and the high pass filter
20 are provided between the amplifier 11 and the frequency detector 13 so that the user can
select and apply it to the device by the switch SW2 that can be operated as needed. It is As in the
first embodiment, the frequency detector 13 is formed of a bridge circuit having a temperature
sensitive resistor in its circuit element.
[0035]
The electro-mechanical-acoustic transducer 12 has at least two natural resonance frequencies,
generates vibration at a low frequency natural resonance frequency f01, and generates sound at
a high frequency natural resonance frequency f02. When vibration occurs, the switch SW2 is
turned on by the selection signal D corresponding to the state of the selection switch (not shown)
which can be operated by the user as necessary, and the high frequency f02 is cut by the low
pass filter 19 Pass f01. When sound is generated, the switch SW2 is turned to the B side by the
signal D, the low frequency f01 is cut by the high pass filter 20, and the high frequency f02 is
passed. When only vibration or sound is to be generated, the switch SW2 may be normally
placed in either a or b. It is also possible to turn on and off the switch SW1 with the signal C as a
repetitive pulse of a predetermined cycle to generate intermittent vibration or sound. On the
other hand, if the switch SW2 is switched alternately to the A side while the switch SW1 is in the
ON state, vibration and sound can be alternately generated in time division. The vibration and the
sound may be generated simultaneously by passing the two natural resonance frequencies with
only one of the low pass filter 19 and the high pass filter 20.
[0036]
In addition, in the case of using three or more natural resonance frequencies and using the
natural resonance frequency surrounded by the other two resonance points, a band pass filter is
used instead of both filters 19 and 20 in FIG. 4. It is also possible.
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[0037]
According to the above configuration, when used for a cellular phone, it is possible to extremely
easily select the vibration and the sound generation by preventing the non-target self-oscillation.
In addition, stable output against temperature change can be obtained.
[0038]
Fifth Embodiment A fifth embodiment of the present invention will be described with reference
to the block circuit diagram of FIG. The main difference between this embodiment and the fourth
embodiment is that the limiter 21 is inserted on the output side of the frequency detector 13. As
in the first embodiment, the frequency detector 13 is formed of a bridge circuit having a
temperature sensitive resistor in its circuit element.
[0039]
With the above configuration, the output level of the frequency detector 13 is limited to prevent
an excessive input due to self-oscillation to the amplifier 11 or the electro-mechanical-acoustic
converter 12.
[0040]
Sixth Embodiment The sixth embodiment of the present invention will be described with
reference to the block circuit diagram of FIG.
The main difference between the present embodiment and the third embodiment is that the
switch SW3 is provided between the signal processing unit 36 and the receiver 38. As in the first
embodiment, the frequency detector 13 is formed of a bridge circuit having a temperature
sensitive resistor in its circuit element.
[0041]
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Normally, the receiver's listening sound, which is the sender's speaking voice, is reproduced by
the receiver 38 while the cellular phone is listened to. Therefore, the sound pressure reproduced
from the receiver 38 is low, and the earpiece can not be heard when the cellular phone is
separated from the ear. Also, the sound pressure level reproduced by the receiver 38 is legally
regulated to be larger than necessary because it leads to ear damage. Therefore, a switch SW3 is
provided in front of the receiver 38, the switch SW1 is turned off, the output from the frequency
detector 13 is cut off, and a reception signal as an output of the signal processing unit 36 is input
to the amplifier 11 by the switch SW3, If the signal is amplified at 11 and reproduced by the
electro-mechanical-acoustic converter 12, the reception sound can be heard even when the ear is
removed from the mobile phone. Also, the signal to be reproduced may be not only the receiving
sound but also a music signal or a message message. Alternatively, vibration may be generated
by the electro-mechanical-acoustic transducer 12. Furthermore, the reproduction of the reception
sound may be performed not only when receiving the reception sound but also when exchanging
a conversation between the transmitter and the receiver.
[0042]
Seventh Embodiment A seventh embodiment of the present invention will be described with
reference to the block circuit diagram of FIG. The main difference between the present
embodiment and the sixth embodiment is that the output of the switch SW3 is inserted after the
amplifier 11. In this case, the received sound sent from the signal processing unit 36 to the
switch SW 3 is amplified to the sound pressure level necessary for reproduction by the electromechanical-acoustic converter 12. As a result, adjustment of the amplification factor of the
amplifier 11 and the like can be eliminated.
[0043]
Eighth Embodiment An eighth embodiment of the present invention will be described with
reference to the block circuit diagram of FIG. In the figure, 12 is an electro-mechanical-acoustic
transducer, 25 is a first oscillator that outputs a low level in a frequency band including the
resonant frequency of the electro-mechanical-acoustic transducer 12, and 26 is an oscillator. A
second oscillator controlled by a control unit 32 described later, 27 is a switch for switching the
input to the electro-mechanical-acoustic transducer 12 between the first oscillator 25 and the
second oscillator 26, and 28 is an electrical switch ̶A frequency detector that detects the
resonance frequency of the machine-acoustic transducer 12, 29 is a voltage comparison circuit
that detects the potential difference between the output voltage of the frequency detector 28 and
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a preset reference potential, and 32 is an embodiment The control unit controls the first
oscillator 25 to the switch 27 in response to the signal C described in the first embodiment. As in
the first embodiment, the frequency detector 28 is a bridge circuit having a temperature
sensitive resistor in its circuit element.
[0044]
The operation of the electro-mechanical-acoustic transducer configured as described above will
be described. First, the first transmitter 25 is oscillated in a state where the switch 27 is on the
side of the first transmitter 25 according to an instruction of the control unit 32. The oscillation
is performed by sweeping a frequency band including the resonance frequency of the electromechanical-acoustic transducer 12. The sweep signal is detected by the frequency detector 28.
At the same time, the voltage comparison circuit 29 compares the potential difference between
the output voltage of the frequency detector 28 and the reference potential. When the potential
difference becomes equal to or higher than the reference potential, the switch 27 is switched to
the second oscillator 26 side to oscillate the second oscillator 26 and output it to the electromechanical-acoustic converter 12 for electro-mechanical-acoustic conversion. The unit 12 is
operated at the oscillation frequency at this time.
[0045]
Next, the switch 27 is switched to the first oscillator 25 side. The frequency of the sweep signal
at that time is higher than the first oscillation frequency. The sweep signal is detected by the
frequency detector 28 as described above. At the same time, the voltage comparison circuit 29
compares the potential difference between the output voltage of the frequency detector 28 and
the reference potential. When the potential difference becomes equal to or higher than the
reference potential, the switch 27 is switched to the second oscillator 26 side to oscillate the
second oscillator 26 and output it to the electro-mechanical-acoustic converter 12 for electromechanical-acoustic conversion. The unit 12 is operated again at the oscillation frequency at this
time.
[0046]
Repeat the above operation. In this way, the output of the natural resonance frequency is input to
the electro-mechanical-acoustic transducer 12 by the second oscillator 26 to cause the electro-
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mechanical-acoustic transducer 12 to either vibrate or emit sound. The resonance frequency can
be found extremely easily, and the operation at this resonance frequency can be performed
extremely easily and rapidly as compared with the first to sixth embodiments.
[0047]
When the voltage comparison circuit 29 confirms that the resonance point is shifted due to a
change in the environment and the potential difference level is decreased, the control unit 32
drives the switch 27 again to switch to the first oscillator 25. By changing the detection of the
initial resonance frequency described above, it is possible to cope with environmental changes.
[0048]
Embodiment 9 Embodiment 9 of the present invention will be described with reference to the
block circuit diagram of FIG.
In the description, the same parts as in the eighth embodiment will be omitted. The difference
from the seventh embodiment is that the oscillating means is only the oscillating portion 31.
First, the resonance frequency is detected by the frequency detector 28, and the detection result
is notified to the control unit 32 through the voltage comparison circuit 29. Next, the control unit
32 instructs this oscillating frequency to the oscillating unit 31. The oscillating unit 31 oscillates
such that the electro-mechanical-acoustic transducer 12 is sufficiently driven (vibrated and / or
generated) at this resonance frequency. As in the first embodiment, the frequency detector 28 is
a bridge circuit having a temperature sensitive resistor in its circuit element.
[0049]
The detection of the resonant frequency accompanying the change in the environment and the
subsequent oscillation of the resonant frequency are the same as the operation of the seventh
embodiment and thus will not be described.
[0050]
With the above configuration, the number of oscillation means can be reduced, and the provision
of an electro-mechanical-acoustic transducer with a simple circuit configuration becomes
possible.
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16
[0051]
Further, by instructing the two resonance frequencies from the control unit 32 to the oscillation
unit 31 by time division, the oscillation unit 31 can be oscillated by the two resonance
frequencies by time division.
As a result, vibration and sound can be alternately generated from the electro-mechanicalacoustic transducer 12.
This reduces the number of oscillation means to one, and constantly monitors and corrects the
shift of the resonance frequency due to environmental changes etc., so that a stable resonance
state can be maintained.
[0052]
The electro-mechanical-acoustic conversion devices described in the seventh and eighth
embodiments can be integrated as a microcomputer except for the electro-mechanical-acoustic
converter 12.
[0053]
Furthermore, in the present embodiment, the electro-mechanical-acoustic transducer is a
conductive type using magnetic force generated in a voice coil inserted in a magnetic field, but a
piezoelectric type, an electromagnetic type, etc. may also be used. There is an effect of
[0054]
As described above, according to the configuration of the electro-mechanical-acoustic transducer
of the present invention, the variation of the resonant frequency is always detected by the
detecting means, and it is extremely effective against the change of the use environment
including the temperature change. A stable oscillation output can be obtained efficiently.
[0055]
Brief description of the drawings
[0056]
03-05-2019
17
1 is a block circuit diagram of a main part of a portable terminal using the electro-mechanicalacoustic conversion device according to the first embodiment of the present invention.
[0057]
Fig. 2 A block circuit diagram of a main part of a portable terminal using the electro-mechanicalacoustic conversion device according to the second embodiment of the present invention.
[0058]
3 is a block circuit diagram of the third embodiment.
[0059]
4 is a block circuit diagram of the fourth embodiment.
[0060]
5 is a block circuit diagram of the fifth embodiment.
[0061]
6 is a block circuit diagram of the sixth embodiment.
[0062]
FIG. 7 is a block circuit diagram of the seventh embodiment.
[0063]
8 is a block circuit diagram of the eighth embodiment.
[0064]
9 is a block circuit diagram of the ninth embodiment.
[0065]
Fig. 10 A block diagram of a conventional electro-mechanical-acoustic transducer
03-05-2019
18
[0066]
Fig. 11 A side sectional view of the electro-mechanical-acoustic transducer which is the main part
[0067]
Fig.12 The same frequency characteristic chart
[0068]
Fig. 13 A perspective view of a mobile phone equipped with the same electro-mechanicalacoustic transducer
[0069]
Explanation of sign
[0070]
DESCRIPTION OF REFERENCE NUMERALS 10 oscillator 11 amplifier 12 electric-mechanicalacoustic converter 13 frequency detector 16, 21 limiter 19 low pass filter 20 high pass filter 25
first oscillator 26 second oscillator 28 frequency detector 31 oscillation unit 32 control unit
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