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DESCRIPTION JPH04295792

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DESCRIPTION JPH04295792
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
alarm clock capable of outputting an alarm sound at a set time and outputting a message voice
such as time notification.
[0002]
2. Description of the Related Art Conventionally, as an alarm clock, an alarm sound such as an
electronic sound or a buzzer sound is sent out from a speaker at a set time, and a message sound
such as a time announcement sound is sent out from a speaker. An alarm clock is provided. A
dynamic speaker is generally used as the speaker.
[0003]
By the way, since the dynamic speaker has a weak directivity, the sound sent from the speaker
can be made to be heard only by the person who wants to hear it, and the other person lying in
the vicinity can not hear the sound. It can not be done. That is, even if the user of the alarm clock
wants to get up earlier than other people or if he / she wants to confirm the time by the time
notification voice during the night, the alarm sound or the notification sound is heard by the
other person sleeping. There is a problem of disturbing sleep.
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[0004]
In order to solve such a problem, it has been considered to limit the sound field by using a
speaker having strong directivity as a speaker, and it is considered that non-directive primary
sound waves such as ultrasonic waves are not used. Attention is focused on parametric speakers
that generate secondary sound waves that are audible sounds by linear parametric action. The
parametric speaker operates according to the following principle. That is, as shown in FIG. 3,
when the parametric speaker 10 having the ultrasonic transducer is driven at two different
frequencies F1 and F2 different from each other, the primary sound wave (shown by the solid
line) output from the ultrasonic transducer is air Interfere with each other to generate the
difference component F2-F1 of the frequency of the primary sound wave and the sum
component F2 + F1 as a secondary sound wave (indicated by a broken line). The sound pressure
of the secondary sound wave generated by such a phenomenon reaches a practical level if a very
strong sound field is formed using a highly directional ultrasonic wave as the primary sound
wave. Further, as shown in FIG. 4, if the frequency difference between the primary sound waves
F1 and F2 is made to be an audible frequency, a secondary sound wave of an audible frequency
AF will be generated as the difference component F2-F1. Such a phenomenon is referred to as
nonlinear parametric action, and the directivity of the generated secondary sound wave is weaker
than the directivity of the primary sound wave but shows a pattern relatively close to the primary
sound wave (ellipse in FIG. 3) pattern). Therefore, if an ultrasonic wave with high directivity is
used as the primary sound wave, the directivity of the secondary sound wave, which is an audible
sound, also becomes strong.
[0005]
As a system for driving the ultrasonic transducer 1, as shown in FIG. 5, an amplitude modulated
wave drive system is known which is driven by a modulated signal obtained by amplitude
modulation. In the amplitude modulation wave drive method, an audio signal corresponding to an
alarm sound or message voice is output from the clock unit 11, and a carrier signal of a
fundamental frequency is amplitude-modulated by the audio signal in the modulation unit 12.
The modulated signal is amplified in the drive circuit 13, and the ultrasonic transducer 1 is
driven by the output of the drive circuit 13. As a modulation method, a carrier suppressed double
sided band modulation method or the like is used. As described above, when the ultrasonic
transducer 1 is driven by the modulated signal, it is possible to generate a secondary sound wave
of audio frequency as a beat component due to the interference of the primary sound wave.
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[0006]
As described above, since a parametric speaker requires a strong sound field of primary sound
waves, it is common to use a plurality of ultrasonic transducers 1 to secure a required sound
pressure level. In addition, since strong ultrasonic waves are generated as primary sound waves,
it is necessary to prevent ultrasonic waves from adversely affecting the human body. For this
reason, in addition to the ultrasonic transducer 1 that sends out the primary sound wave, the
parametric speaker 10 is a sound surrounding the space (parametric acoustic array) in which the
secondary sound wave is generated by the nonlinear parametric action of the primary sound
wave. It is usual to provide the tube 2 and the acoustic wave filter 2 for attenuating at least the
primary sound wave in the opening window 3 for taking out the secondary sound wave in the
sound tube 2. Further, in order to suppress the generation of side lobes of the secondary sound
wave, a sound absorbing material 5 is provided on the inner surface of the acoustic cylinder 2.
The sound cylinder 2 is configured by combining a plurality of members, and a bent portion is
formed in the vicinity of the opening window 3. The bent portion is formed of a material that
reflects the sound wave to form the reflection surface 6 to control the direction of the sound
wave transmission, and effectively utilize a relatively small limited space such as a case of an
alarm clock. Acoustic parametric array can be secured.
[0007]
By the way, among the secondary sound waves transmitted from the parametric speaker having
the above-mentioned configuration, strong directivity is exhibited in the high frequency range of
the audio frequency (for example, 2 kHz). There is a problem that the directivity becomes weak
in the low frequency range of the audio frequency (for example, 500 Hz).
[0008]
That is, since the alarm sound can be set to a relatively high frequency, strong directivity can be
obtained, but since the message voice contains a relatively low frequency component, the
directivity becomes weak and other people can not Can not achieve the goal of not disturbing
their sleep.
If the directivity is enhanced to the low frequency region, the aperture diameter is increased,
which causes a problem of enlargement.
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[0009]
The present invention is intended to solve the above-mentioned problems, and while making it
relatively small, in both the alarm sound and the message voice, the area where the sound
pressure level is relatively high is used for the sleep of another person. It is an object of the
present invention to provide an alarm clock that can have a limited range that does not interfere
with the operation.
[0010]
According to the first aspect of the present invention, in order to achieve the above object, an
ultrasonic transducer for transmitting an ultrasonic wave as the primary sound wave is provided,
and the nonlinear parametric action of the primary sound wave is possible. Audio signal output
means for selectively outputting a parametric speaker for transmitting a secondary sound wave
which is a listening sound, and a first audio signal corresponding to an alarm sound output at a
set time and a second audio signal corresponding to a message audio And an alarm clock
including amplitude modulation of a carrier wave signal by an audio signal and modulation
means for driving an ultrasonic transducer by a modulated signal, wherein a sound pressure level
of a secondary sound wave corresponding to the first audio signal is sleepy The sound pressure
level is set to a level that allows transition from the state to the awake state, and the sound
pressure level of the secondary sound wave corresponding to the second audio signal is set to an
audible minimum degree in the awake state It's has a control means.
[0011]
In the second aspect of the invention, the parametric speaker comprises a plurality of ultrasonic
transducers, and the sound pressure level control means is driven at the time of generation of the
first audio signal and at the time of generation of the second audio signal. The number of
ultrasonic transducers is changed.
According to the third aspect, the sound pressure level control means changes the degree of
modulation of the modulated signal between the time of generation of the first audio signal and
the time of generation of the second audio signal.
[0012]
According to the first aspect of the present invention, by using the parametric speaker, the sound
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field can be limited by the strong directivity for relatively high alarm sound in the frequency
domain. Even if the sound pressure level is set to awaken the user during sleep, it is possible not
to disturb other people's sleep.
Also, although the directivity of the message voice is weak, the sound field is limited by keeping
the sound pressure level as low as possible in view of the fact that the sound field should be kept
as low as possible in view of the fact that it should be heard at awakening. It is possible not to
disturb people's sleep.
[0013]
The constructions of claims 2 and 3 are desirable embodiments.
[0014]
Embodiment 1 As shown in FIG. 1, a parametric speaker 10 includes a plurality of ultrasonic
transducers 1a, 1b and 1c, each of which is an ultrasonic transducer 1a, 1b and 1c. They are
driven by the outputs of the drive circuits 13a, 13b and 13c respectively.
The clock unit 11 generates an alarm signal generation unit 11a that outputs an audio signal
corresponding to an alarm sound having a relatively high frequency at a set time, and a time
notification voice by synthetic sound when the touch sensor 11c is touched with a hand or the
like. And a message signal generator 11b for outputting a voice signal corresponding to the
message voice. The alarm signal generation unit 11 a and the message signal generation unit 11
b serve as audio signal output means for outputting an audio signal to the modulation unit 12.
The modulation unit 12 amplitude-modulates a carrier signal of a predetermined frequency
(ultrasonic frequency) with an audio signal. Relay contacts r1 and r2 as switch elements are
inserted between the modulator 12 and the two drive circuits 13a and 13c, respectively. The
relay contacts r1 and r2 are controlled to open and close by a control circuit 14 that operates in
response to the signal from the touch sensor 11c. That is, the relay contacts r1 and r2 are
normally closed so that the modulated signal from the modulation unit 12 can be input to the
drive circuits 13a and 13c, but when the touch sensor 11c is touched, the control circuit 14 is
turned on. Controlled and open. That is, the alarm sound is sent out at a relatively high sound
pressure level by the three ultrasonic transducers 1a, 1b, 1c, and the message voice is sent out at
a relatively low sound pressure level by one ultrasonic transducer 1b. It is Here, the sound
pressure level of the alarm sound is set to the extent that the user can shift from the sleep state
to the awake state, and the sound pressure level of the message voice is set to the minimum level
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that can be heard when the user is in the awake state Be done. As described above, the relay
contacts r1 and r2 and the control circuit 14 constitute a sound pressure level control means.
[0015]
According to the above configuration, the alarm sound with a relatively high frequency and
strong directivity can be awakened by the user during sleep by increasing the sound pressure
level, and includes a low frequency component and directed. For message voices that become less
sexual, the sound field is limited by lowering the sound pressure level. In the above embodiment,
in order to simplify the description, three ultrasonic transducers 1a, 1b and 1c are provided, and
only one ultrasonic transducer 1b is driven for message voice. Although shown, the number of
ultrasonic transducers 1a, 1b, 1c is not limited to this, and may be appropriately set so as to
obtain a target sound pressure level.
[0016]
According to this configuration, the sound pressure level of the ultrasonic wave, which is the
primary sound wave, is also lowered when the message voice is sent out, so even if the message
voice is sent over a relatively long time, the ultrasonic wave is There is little impact on the human
body by (Embodiment 2) In this embodiment, as shown in FIG. 2, the sound pressure level control
means comprises a variable attenuator 15 for adjusting the level of the audio signal inputted to
the modulator 12, and attenuation by the variable attenuator 15. It comprises with the control
circuit 14 which sets quantity. That is, when the hand or the like is touched on the touch sensor
11c, the amount of attenuation by the variable attenuator 15 is made larger than that in the
previous state. As a result, the voice signal corresponding to the message voice has a smaller
degree of modulation, and the sound pressure level of the message voice becomes smaller than
that of the alarm sound. Also in this configuration, the same effect as that of the first
embodiment can be obtained. In addition, with regard to message voice, since the degree of
modulation is small, the ultrasonic transducer 1 is driven in the region where the input / output
characteristics are linear, the clarity is enhanced, and the voice can be easily heard. .
[0017]
When the modulation degree is switched, the levels of both the carrier signal and the audio
signal may be changed.
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[0018]
As described above, according to the present invention, by using the parametric speaker, the
sound field can be limited by the strong directivity for relatively high alarm sound in the
frequency domain. There is an advantage that setting the sound pressure level to awaken the
sleeping user can prevent disturbing the sleep of another person sleeping nearby.
Also, although the directivity of the message voice is weak, the sound field is limited by keeping
the sound pressure level as low as possible in view of the fact that the sound field should be kept
as low as possible in view of the fact that it should be heard at awakening. It has the effect of
being able to prevent people from sleeping.
[0019]
Brief description of the drawings
[0020]
1 is a block diagram showing a first embodiment.
[0021]
2 is a block diagram showing a second embodiment.
[0022]
3 is a principle explanatory view of a parametric speaker.
[0023]
4 is an operation explanatory diagram of the parametric speaker.
[0024]
5 is a schematic diagram showing a basic configuration of the alarm clock.
[0025]
Explanation of sign
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[0026]
Reference Signs List 1 ultrasonic transducer 1a ultrasonic transducer 1b ultrasonic transducer 1c
ultrasonic transducer 10 parametric speaker 11 clock unit 11a alarm signal generation unit 11b
message signal generation unit 11c touch sensor 12 modulation unit 13 drive circuit 13a drive
circuit 13b drive Circuit 13c Drive circuit 14 Control circuit 15 Variable attenuator r1 Relay
contact r2 Relay contact
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