JP2002044789

Patent Translate
Powered by EPO and Google
Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2002044789
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
method and apparatus for generating an audible sound wave by combining two ultrasonic waves
in space.
[0002]
2. Description of the Related Art Conventionally, as an electrical frequency synthesis method, for
example, the method described in JP-A-58-120305 is known. This is to obtain a sine wave signal
by adding or multiplying two clock signals having different frequencies through a filter and then
rectifying and removing high frequency components through a low pass filter.
[0003]
SUMMARY OF THE INVENTION The conventional frequency synthesis method relates to
frequency synthesis on an electric circuit to the last, and generates an audible sound wave by
synthesizing ultrasonic waves in space. It is not possible.
[0004]
An object of the present invention is to provide an audio sound wave generation method and
apparatus capable of generating an audio sound wave by synthesizing ultrasonic waves in a
space.
05-05-2019
1
[0005]
SUMMARY OF THE INVENTION The above object is to add the amplitudes of the external audio
signal to the two signals to which feedback is applied 180 degrees out of phase with each other
at the ultrasonic fundamental frequency. Means for adding and modulating the amplitude, and
then creating means for creating two ultrasonic waves created by sampling at the fundamental
frequency, and emitting these two ultrasonic waves from two directions so as to cross at any one
point in space This is achieved by generating an audible sound wave by combining two ultrasonic
waves at a crossing point.
[0006]
Further, the above object is to provide a feedback circuit for applying feedback with a phase lag
of 180 degrees to each other at the ultrasonic fundamental frequency to two signals of the
addition output, and to delay the phase by 180 degrees to each other by the feedback circuit. A
signal adder for adding the amplitude of the external audio wave signal to each of the two
feedback-added signals and performing amplitude modulation, and alternately activating each of
the signal adders every half cycle of the ultrasonic fundamental frequency A signal adder
selection signal generation circuit, a sine wave generation circuit for generating a sine wave from
the output amplitude modulation signal of each signal adder, and the two generated ultrasonic
waves at any one point in space from two directions This is achieved by providing an electroacoustic transducer that emits so as to cross.
[0007]
According to the above means, the feedback circuit delays the outputs of the two signal adders
by 180 degrees in phase with each other at the fundamental frequency and feeds the outputs to
the opposite signal adder.
The audio band sound signal from the outside is input to the other input terminal in any signal
adder, and the amplitude of the external sound band sound signal is added to the feedback signal
delayed in phase by 180 degrees to obtain amplitude modulation. It takes place.
A selection signal is added to the above two signal adders from the signal adder selection signal
generation circuit, and is alternately controlled every half cycle of the fundamental frequency.
05-05-2019
2
As a result, amplitude modulated pulse signals sampled at the fundamental frequency are
alternately output from the two signal adders with a phase difference of 180 degrees.
Since each amplitude modulation pulse signal output from each signal adder is a + side pulse
signal, the sine wave generation circuit generates a sine wave ultrasonic wave by adding a − side
pulse delayed in phase by 180 degrees on the + side pulse. Do. The thus-generated sine wave
ultrasonic waves have an ultrasonic wave A and an ultrasonic wave B having a phase difference
of 180 degrees.
[0008]
Next, the two generated ultrasonic waves A and B are input to two electroacoustic transducers
(speakers) and radiated from two directions into space. The radiation direction is such that the
ultrasonic waves A and B emitted at any one point in space cross each other. Thus, two ultrasonic
waves are synthesized at the crossover point. The two ultrasonic waves A and B have the same
frequency, are 180 degrees out of phase, and are amplitude modulated and have different
amplitudes, and are synthesized into another ultrasonic wave C by being synthesized. The
synthetic ultrasonic wave C contains a modulation component of the audible sound wave band,
and if it is heard through the low pass filter characteristic of the ear, the audible sound wave can
be heard. The directions of radiation from the two speakers can be crossed at any point in space,
and audible sound waves can be generated at any point.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present
invention will be described with reference to the drawings.
[0010]
FIG. 1 shows a schematic block diagram of an audible sound wave generator according to an
embodiment of the present invention, and FIG. 2 explains the principle of synthesizing the
ultrasonic waves to generate an audible sound wave. .
[0011]
05-05-2019
3
In FIG. 1, a triangular wave signal input from the microphone 3 is amplified by the audio
amplifier 4 and then input to the input terminals of the signal adders 5 and 6 respectively.
The outputs of the two signal adders 5 and 6 are subjected to feedback delayed in phase by 180
degrees at the ultrasonic fundamental frequency by the feedback circuits 7 and 8, respectively, to
the input terminals of the signal adders 5 and 6 opposite to each other. input.
The basic signal oscillator 1 generates an ultrasonic fundamental frequency signal, and based on
this basic signal, the signal adder selection signal generating circuit 2 generates a signal that
alternately enables two signal adders 5 and 6 every half cycle. , Add to signal adders 5 and 6.
Further, the fundamental frequency signal of the fundamental signal oscillator 1 is applied to the
feedback circuits 7 and 8, and the outputs of the signal adders 5 and 6 are controlled such that
feedback with a phase lag of 180 degrees at the fundamental frequency is applied. The outputs
of the signal adders 5 and 6 are made into sine waves by sine wave forming circuits 9 and 10,
and are emitted from the speakers 11 and 12 into space as ultrasonic waves A and B.
[0012]
The operation of generating an audible sound wave by ultrasonic synthesis by the abovedescribed apparatus will be described with reference to FIG. An audio triangular wave signal is
input from the microphone 3 and amplified by the audio amplifier 4. The microphone input
signal changes as +, +, +, +, +, +, 0,-,-,-,-,-, 0, +,... Every 180 degrees of the fundamental cycle
ultrasonic wave.
[0013]
The amplified signals are added to the feedback signals from the feedback circuits 7 and 8 by
two signal adders 5 and 6, respectively. The fundamental wave (FIG. 2) of the ultrasonic wave is
added to the feedback circuits 7 and 8 from the fundamental signal oscillator 1, and the outputs
of the signal adders 5 and 6 are input to this and the feedback delayed in phase by 180 degrees
at the fundamental frequency Then, the signal adders 5 and 6 on the opposite side are input.
[0014]
05-05-2019
4
The signal adder 6 becomes effective every positive half cycle of the ultrasonic fundamental
wave in response to the selection signal from the selection signal generation circuit 2, and the
outputs (3, 8, 9, 6, The amplitude (+, +, +, +,-,-, +, ...) of the triangular wave input signal from the
audio amplifier 4 is added to the feedback signal whose phase is delayed 180 degrees by the
feedback circuit 7 Modulate and output. Therefore, the output signal of this signal adder 6 is a
positive pulse signal (+ = 1, 3 + = 6, 8+ shown in FIG. 2) which is amplitude-modulated by a
triangular wave signal sampled with an ultrasonic fundamental wave. = 9, 9-8, 6-3, 1-0 = 0, 0 = 1.
[0015]
Further, the signal adder 5 becomes effective every negative half cycle of the ultrasonic
fundamental wave by the selection signal from the selection signal generation circuit 2 and
outputs (1, 6, 9, , The amplitude (+, +, 0,-,-, 0,...) Of the triangular wave input signal from the
audio amplifier 4 to the feedback signal whose phase is delayed by 180 ° in the feedback circuit
8 Add, amplitude modulate and output. Therefore, the output signal of the signal adder 5 is
amplitude modulated with a triangular wave signal having a phase difference of 180 degrees
with the ultrasonic wave A, and the positive pulse signal (1 + = 3, 6 + = 8) of the ultrasonic wave
B shown in FIG. , 9 + 0 = 9,8− = 6,3−1,0 + 0 = 0,.
[0016]
The generated + side pulse signal of the ultrasonic wave A is input from the signal adder 6 to the
sine wave generation circuit 9, and the + side pulse is added with the − side pulse signal delayed
in phase by 180 degrees to add a sine wave An ultrasonic wave A (FIG. 2) is created and input to
the speaker 11. In addition, the positive side pulse signal of the ultrasonic wave B is input from
the signal adder 5 to the sine wave generation circuit 10, and the positive side pulse is added
with the negative side pulse signal whose phase is delayed by 180 degrees. 2) are created and
input to the speaker 12.
[0017]
The loudspeakers 11 and 12 radiate ultrasonic waves A and B having different amplitudes due to
amplitude modulation into the space at the same frequency (ultrasonic wave) with a phase
05-05-2019
5
difference of 180 degrees. The directions are variable, and when the speakers 11 and 12 are
directed to cross the radiating ultrasonic waves A and B at one point in space, the ultrasonic
waves A and B are synthesized at the crossing points. The composite wave of the ultrasonic
waves A and B has an ultrasonic waveform like the composite wave C shown in FIG. Since this
synthetic wave C contains modulation components of triangular sound wave as shown by dotted
line in FIG. 2, only the audible sound wave (triangular wave) is heard through the low pass filter
characteristic of the ear. be able to.
[0018]
By changing the direction of radiation of the speakers 11 and 12 and changing the position of
the intersection point of the two radiated ultrasonic waves, it is possible to transmit the voice
(triangular wave) input to the microphone 3 to any position in space. It is possible to call at a
meeting place or the like, and to individually transmit a message to individual people by using it
like earphone without using the earphone.
[0019]
As described above, according to the present invention, it is possible to generate an audible
sound wave by synthesizing ultrasonic waves in a space, and using this, an audio can be
generated to any point in the space. It can be transmitted.
[0020]
Brief description of the drawings
[0021]
1 is a block diagram of an embodiment of the present invention.
[0022]
2 is a signal waveform diagram showing the ultrasonic wave synthesis principle of the present
invention.
[0023]
Explanation of sign
[0024]
05-05-2019
6
DESCRIPTION OF SYMBOLS 1 ... Basic signal oscillator, 2 ... Signal adder selection signal
generation circuit, 3 ... Microphone, 4 ... Audio amplifier, 5, 6 ... Signal adder, 7, 8 ... Feedback
circuit, 9, 10 ... Sine wave creation circuit, 10 , 11 ... speaker.
05-05-2019
7