JP2009212898A - Ultrasonic acoustic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ultrasonic acoustic apparatus which is constituted of only general components, thereby attaining reduction of costs, the apparatus having a frequency modulator, a preamplifier, a power amplifier and an ultrasonic transmitter. <P>SOLUTION: During driving pulse voltage generation to generate a driving pulse voltage for transmitting an ultrasonic wave from an ultrasonic transmitter in a case where, e.g., an audio signal is inputted to an input, an ultrasonic acoustic apparatus inputs an AC signal based on the audio signal, varies a term for determining ON/OFF of a driving pulse to frequency-modulate the driving pulse voltage, and transmits the ultrasonic wave from the ultrasonic transmitter with the frequency-modulated driving pulse voltage. The functions can be easily achieved by using a general timer, a general logic, a general transistor and a general FET (Field Effect Transistor). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an ultrasonic acoustic apparatus that uses an ultrasonic transmitter to make an analog signal such as an audio signal audible sound, and more specifically, by transmitting an ultrasonic wave including an analog signal such as an audio signal, The present invention relates to an ultrasonic acoustic device that provides information such as audible sound.

  The above apparatus is generally called a parametric speaker, and can transmit information by transmitting an audio signal or the like as information to a medium such as the air using an ultrasonic transmitter capable of transmitting ultrasonic waves. This is a device that performs signal processing using a digital signal processor (DSP) for signal processing when transmitting an ultrasonic wave modulated with an audio signal, etc., from the parametric speaker, and modulates it with the frequency of the ultrasonic band. After that, there is an ultrasonic acoustic device that amplifies to a predetermined power level with a power amplifier and transmits from an ultrasonic transmitter.

In this case, a general method for modulating an audio signal or the like to an ultrasonic frequency is an amplitude modulation method (see, for example, Patent Document 1).
Special Table 2005-516516 Amended March 9, 2006

  However, in this acoustic apparatus, signal processing must be performed on an analog signal such as an audio signal that is input using a semiconductor integrated circuit (LSI: Large Scale Integration) called DSP, and thus the overall configuration of the apparatus is limited. There is a problem that it is complicated and expensive.

  A manufacturer's ultrasonic equipment uses a DSP, and the audio input unit, DSP, amplitude modulation unit, and preamplifier unit use hundreds of electronic components, and the size of the printed circuit board on which these components are mounted. Is 150 × 200 [mm], which is physically large and the cost of electronic components is expensive. The present invention has been made in view of such problems, and uses a DSP with a simple configuration. This is an ultrasonic acoustic device that can transmit various types of information such as voice information from an ultrasonic transmitter. The number of electronic components required to satisfy basic functions is several tens, and the printed circuit board size is 40 x 40 [mm]. Therefore, an ultrasonic acoustic device can be provided at a small size and at a low cost.

  In order to achieve the above object, an ultrasonic acoustic apparatus according to claim 1 transmits an ultrasonic wave by an ultrasonic transmitter that transmits an ultrasonic wave, and a voltage supplied from a power source by the ultrasonic wave transmitter. When generating the drive pulse voltage, a power amplifier that generates a drive pulse voltage, a preamplifier that receives an input of information and inputs an AC signal based on the input information to the power amplifier, and A frequency modulation unit that frequency-modulates the drive pulse voltage generated by the preamplifier by changing a cycle for determining ON / OFF of the drive pulse voltage based on the AC signal input from the previous input unit; The carrier frequency of the frequency modulation unit is a frequency different from the center of the first resonance frequency of the ultrasonic transmitter.

The ultrasonic acoustic device according to claim 2 is the ultrasonic acoustic device according to claim 1, wherein the first resonance frequency of the ultrasonic transmitter is within an occupied bandwidth obtained by modulating the input information by the frequency modulation unit. It is characterized by including.

  The ultrasonic acoustic device according to claim 3 is the ultrasonic acoustic device according to claim 1, further comprising a transmission frequency variable unit that varies a carrier frequency of the frequency modulation unit to an arbitrary frequency, and the frequency modulation unit Modulating at a carrier frequency different from the center of the first resonance frequency of the acoustic wave transmitter, and changing the sound quality of the information output from the ultrasonic transmitter by an arbitrary carrier frequency changed by the frequency modulation unit It is said.

  According to the ultrasonic acoustic apparatus of the first aspect, when information such as an audio signal is input, the ultrasonic transmitter does not use a DSP to generate a drive pulse for transmitting the information. The number of electronic components necessary for satisfying the basic functions can be several tens, and the printed circuit board size is 40 × 40 [mm]. Thus, an ultrasonic acoustic device can be provided at a small size and at low cost.

  According to the ultrasonic acoustic apparatus of claim 2, for example, when information such as an audio signal is input, an arbitrary range can be obtained by matching a sound range to be emphasized with a first resonance frequency of the ultrasonic transmitter. Only the frequency band can be emphasized.

  According to the ultrasonic acoustic device of the third aspect, for example, when information such as an audio signal is input, a simple configuration such as a variable resistor can be provided at low cost without performing complicated signal processing on the information. It is possible to change the sound quality of the information output from the ultrasonic transmitter.

  Hereinafter, an ultrasonic acoustic device according to the best mode for carrying out the present invention will be described with reference to the drawings. As shown in FIG. 1, the ultrasonic acoustic apparatus includes an audio signal input unit 1, a frequency modulation unit 2, a preamplifier 3, a power amplifier 4, and an ultrasonic transmitter 5, and inputs the input audio signal. It is connected so that it can transmit as an audio | voice sound from an ultrasonic transmitter.

Conventionally, this type of modulation and drive circuit has been implemented in the form shown in FIG. 2, and is composed of an audio signal input 6, a DSP 7, an amplitude modulation 8, a preamplifier 9, a power amplifier 10, and an ultrasonic transmitter 11. The connected audio signal is connected to be transmitted as an audible sound from the ultrasonic transmitter.

  FIG. 3 shows the relationship between the carrier frequency of the frequency modulation unit and the frequency that becomes the center of the first resonance frequency of the ultrasonic transmitter. Here, the frequency characteristic 12 of the ultrasonic transmitter efficiently transmits ultrasonic waves. There is a first resonance frequency (for example, 40 [KHz] 13, a carrier frequency 14 of the frequency modulation circuit, and an occupied bandwidth 15 in the frequency modulation).

The overall electrical configuration of the present invention is the configuration shown in FIG. 4. The audio signal input unit 16 is frequency-modulated by a frequency modulation unit 17, and at the same time, the frequency modulation unit is a carrier frequency adjustment unit by a variable resistor 18 can be arbitrarily adjusted. The modulated signal output generated by the frequency modulation unit is supplied to the preamplifier 19, amplified to a predetermined power by the power amplifier 20, and then transmitted from the ultrasonic transmitter 21. In this case, the frequency modulation unit can be constituted by an OP amplifier, a comparator, a general-purpose logic IC, etc. in addition to a general-purpose timer IC (IC: Inte-grated Circuit).
Similarly, it is conceivable that the preamplifier and the power amplifier can also be composed of the same general-purpose parts.

  In this ultrasonic acoustic apparatus, when a signal is input to the audio input unit, the audio signal 16 based on the input is input to the control of the timer 555 of the frequency modulation unit 17. When the audio signal 16 is input to the frequency modulation unit 17 in this way, the frequency modulation unit 16 generates a pulse signal frequency-modulated in the frequency shift region of the occupied bandwidth 15 with the carrier frequency 14 as the center, and a preamplifier. 19, the preamplifier 19 generates a signal capable of driving the ultrasonic transmitter 21 at the same time as the power amplifier 20 in the next stage is electrically operated. The power amplifier 20 is supplied from the preamplifier 19. The frequency-modulated drive pulse is amplified to a predetermined voltage, and the ultrasonic transmitter 21 can perform transmission using the frequency-modulated and amplified drive pulse.

It is a block diagram which shows the structure of the ultrasonic acoustic apparatus which concerns on the best form for implementing this invention. The block diagram which shows the structure of the ultrasonic acoustic apparatus which concerns on the conventional form The figure which showed the frequency characteristic of the 1st resonance frequency of an ultrasonic transmitter, and a frequency modulation part The figure which showed a part of circuit structure of the ultrasonic acoustic apparatus of this invention

Explanation of symbols

1 audio signal input 2 frequency modulation 3 preamplifier 4 power amplifier 5 ultrasonic transmitter 6 audio signal input 7 DSP
8 Amplitude modulation 9 Preamplifier 10 Power amplifier 11 Ultrasonic transmitter 12 Frequency-sound pressure characteristic of ultrasonic transmitter 13 First resonance frequency of ultrasonic transmitter 14 Carrier frequency of frequency modulation 15 Occupied bandwidth of frequency modulation 16 Audio signal input unit 17 Frequency modulation unit 18 Carrier frequency adjustment unit 19 Preamplifier 20 Power amplification unit 21 Ultrasonic transmitter

Claims (3)

  An ultrasonic transmitter that transmits ultrasonic waves, a power amplifying unit that generates a driving pulse voltage for transmitting ultrasonic waves from the voltage supplied from a power source by the ultrasonic transmitter, and an input of information And a preamplifier for inputting an AC signal based on the information input to the power amplification unit, and a period for determining ON / OFF of the drive pulse voltage when generating the drive pulse voltage from the previous period input unit. An ultrasonic acoustic apparatus comprising: a frequency modulation unit configured to change the frequency of the drive pulse voltage generated by the preamplifier by changing the frequency based on the AC signal.   2. The ultrasonic acoustic apparatus according to claim 1, wherein the first resonance frequency of the ultrasonic transmitter is included in an occupied bandwidth obtained by modulating the input information by the frequency modulation unit. .   The ultrasonic acoustic apparatus according to claim 1, further comprising: a transmission frequency variable unit that varies a carrier frequency of the frequency modulation unit to an arbitrary frequency, and the frequency modulation unit includes a center of the first resonance frequency of the ultrasonic transmitter, An ultrasonic acoustic apparatus that modulates with a different carrier frequency and changes the sound quality of information output from the ultrasonic transmitter according to an arbitrary carrier frequency changed by the frequency modulation unit.

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