JPH109845A - Ultrasonic signal generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently transfer data by preventing the generation of sagging in the rising and falling of an ultrasonic signal. SOLUTION: A transmission signal is modulated by a carrier wave signal in a pulse modulator 3 to be converted to a modulation signal. Thereafter, a predetermined number of pulse signals having a predetermined wave height value is added to the modulation signal in synchronous relation to the rising of the transmission signal by an overvoltage applying device 4. A pulse signal being a signal inverse to the modulation signal in phase and having a predetermined pulse number and a predetermined wave height value is added to the signal from an overvoltage applying device in synchronous relation to the falling of the transmission signal by an inverse exciting applying device 5. By this constitution, the sagging of an ultrasonic signal is corrected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic signal generator capable of efficiently outputting a signal by shortening the rise or fall time of the ultrasonic signal and increasing the output rate of the ultrasonic signal. Related to the device.

[0002]

2. Description of the Related Art Conventionally, ultrasonic signals are sometimes used for distance measurement and data communication. Such an ultrasonic signal is shown in FIG.
It is emitted by an ultrasonic signal generator as shown in FIG.

The ultrasonic signal generator includes a carrier oscillator for generating a carrier signal, a transmission signal generator for generating a transmission signal, a pulse modulator for modulating a transmission signal with the carrier signal and outputting the modulated signal. It has a drive circuit 6 for amplifying the signal level of the modulation signal from the pulse modulator 3 to a predetermined level, and an ultrasonic transducer 7 for emitting an ultrasonic signal based on the drive signal from the drive circuit 6.

FIG. 5 shows a signal waveform output from each block having the above configuration. A carrier signal composed of continuous pulses as shown in FIG. 5A is output from the carrier oscillator 1, and a transmission signal of intermittent pulses as shown in FIG. 5B is output from the transmission signal generator 2. .

[0005] The transmission signal is modulated by the carrier signal in the pulse modulator 3 and becomes a modulation signal of a burst wave as shown in FIG.

The driving circuit 6 amplifies the signal level of the modulation signal to a predetermined level and outputs the amplified signal to the ultrasonic vibrator 7, whereby the ultrasonic vibrator 7 generates an ultrasonic wave having a waveform as shown in FIG. A signal is emitted.

[0007]

However, in general, the ultrasonic oscillator has poor rising characteristics at the start of oscillation and falling characteristics at the end of oscillation, and therefore, as shown in FIG. At the falling edge, a signal sag occurs, which complicates the design of the apparatus, and has a problem that the output rate of the ultrasonic signal cannot be increased.

That is, as shown in FIG. 5, the burst width t3 of the ultrasonic signal based on the transmission signal having the pulse width t1 becomes larger than t1 due to the sag of the signal (t3> t1). Therefore, the time interval t4 of the ultrasonic signal corresponding to the time interval t2 until the next transmission signal is shortened by δt = t3−t1, and the time interval t2 of the pulse is generated in consideration of the circumstances in generating the transmission signal. Must be set.

Therefore, in a remote controller or the like that uses an ultrasonic signal as a data signal, there is a disadvantage that the data transfer time becomes long.

In the distance measurement in which the ultrasonic wave is intermittently transmitted and the distance is measured from the time until the reflected wave is received, if the signal sags, it is necessary to lengthen the interval between the ultrasonic signals. Inconveniences such as a decrease in measurement resolution and an increase in the minimum measurable distance occur.

Accordingly, the present invention provides an ultrasonic signal generating apparatus which prevents data from sagging and enables efficient data transfer and the like and does not need to consider the sagging in designing. The purpose is to:

[0012]

In order to solve the above-mentioned problems, the invention according to claim 1 comprises a carrier signal generator for generating a carrier signal composed of continuous pulses, and a transmitter for generating a transmitted signal as an information signal. A wave signal generator, a pulse modulator that modulates the transmission signal into a modulation signal composed of a plurality of pulses by the carrier signal, and a peak value of the pulse with respect to a predetermined number of pulses from the first pulse of the modulation signal. A head area pulse changing means for making a pulse having a larger peak value;
Following the tail pulse of the modulation signal, a tail region pulse changing unit that adds a pulse having a phase opposite to that of the modulation signal, and the modulation signal is partially changed by the head region pulse changing unit and the tail region pulse changing unit. A driving circuit that amplifies the signal with a predetermined gain, and an ultrasonic transducer that emits an ultrasonic wave based on a signal from the driving circuit.

That is, a carrier signal composed of continuous pulses is generated by a carrier signal generator, and a transmission signal, which is an information signal, is generated by a transmission signal generator. Then, the carrier signal and the transmission signal are input to a pulse modulator, and the transmission signal is modulated by a plurality of pulses using the carrier signal to be a modulated signal. In order to correct the rising of the ultrasonic signal emitted from the ultrasonic transducer by the leading area pulse changing means, a predetermined number of pulses from the leading pulse of the modulated signal are larger than the peak value of the modulated signal. In order to change the pulse to a pulse having a peak value, and to correct the fall of the falling edge of the ultrasonic signal emitted from the ultrasonic transducer by the tail region pulse changing means, the modulation signal is followed by the tail pulse of the modulation signal. Add a pulse of opposite phase. As described above, the modulation signal changed by the head area pulse changing means and the tail area pulse changing means is amplified with a predetermined gain by a drive circuit, and an ultrasonic transducer is oscillated to emit an ultrasonic wave. And

According to a second aspect of the present invention, there is provided a carrier signal generator for generating a carrier signal comprising a continuous pulse, a transmission signal generator for generating a transmission signal as an information signal, and a transmission signal generator for transmitting the carrier signal by the carrier signal. A pulse modulator for modulating a signal into a modulation signal composed of a plurality of pulses, and a head area pulse changing unit for converting a predetermined number of pulses from the head pulse of the modulation signal into a pulse having a peak value larger than the peak value of the pulse A digital signal processing device comprising: a trailing pulse change unit for adding a pulse having a phase opposite to that of the modulation signal following the tail pulse of the modulation signal; and converting the signal from the digital signal processing device into an analog signal. A digital / analog converter for conversion, a drive circuit for amplifying a signal from the digital / analog converter with a predetermined gain, and a signal from the drive circuit. By and having an ultrasonic transducer for emitting ultrasonic waves.

That is, a carrier signal composed of continuous pulses is generated by a carrier signal generator, a transmission signal as an information signal is generated by a transmission signal generator, and input to a digital signal processing device. Then, in the digital signal processing device, a transmission signal is modulated by a plurality of pulses with a carrier signal in a pulse modulation section to be a modulated signal. For this modulation signal, a predetermined number of pulses from the head pulse of the modulation signal are larger than the peak value of the pulse in order to correct the rising of the ultrasonic signal emitted from the ultrasonic transducer by the head region pulse changing unit. Change to pulse with peak value,
Further, in order to correct the falling of the falling edge of the ultrasonic signal emitted from the ultrasonic transducer by the tail region pulse changing unit, a pulse having a phase opposite to that of the modulation signal is added following the tail pulse of the modulation signal. As described above, the modulation signal changed by the head area pulse changing unit and the tail area pulse changing unit is converted into an analog signal by a digital / analog converter, and is amplified by a predetermined gain by a driving circuit, and the ultrasonic oscillator is used. And emits ultrasonic waves.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration block diagram of an ultrasonic signal generator according to the present embodiment.

The ultrasonic signal generator comprises a carrier oscillator for generating a carrier signal which is a continuous pulse signal, a transmission signal generator for generating a transmission signal which is an information signal, and a carrier signal for generating a carrier signal which is an information signal. A pulse modulator 3, which outputs a modulated signal by adding a predetermined amount of signal to the modulated signal in synchronism with the rise of the transmitted signal, and outputs a pulse signal. A pulse having a predetermined peak value and a phase opposite to that of the modulation signal (including the opposite polarity) added to the signal from the overvoltage applicator 4 in synchronism with the fall of the transmission signal and outputted. It has a reverse excitation applicator 5 as a means, a drive circuit 6 for amplifying a signal from the reverse excitation applicator 5 with a predetermined gain, and an ultrasonic transducer 7 for emitting an ultrasonic signal by a drive signal from the drive circuit 6. ing.

FIG. 2 shows signal waveforms output from each block in the ultrasonic signal generator having the above-mentioned configuration. A carrier signal composed of a pulse signal as shown in FIG. 2A is output from the carrier oscillator 1, and a transmission signal of an intermittent pulse as shown in FIG. Is output.

Then, the transmission signal is modulated by the carrier signal in the pulse modulator 3, becomes a burst wave as shown in FIG. 2C, and is output from the pulse modulator 3 to the overvoltage applying device 4.

A transmission signal from the transmission signal generator 2 is input to the overvoltage applicator 4 as a synchronization signal. Thereby, the overvoltage applicator 4 adds a pulse signal having a predetermined peak value to the modulation signal so as to make the signal larger by a predetermined amount than the peak value of the modulation signal in synchronization with the rise of the transmission signal,
A signal as shown in FIG. 2D is output to the reverse excitation applicator 5.

Also, the reverse excitation applicator 5 has an overvoltage
Similarly to the above, a transmission signal is input from the transmission signal generator 2 as a synchronization signal, and a modulation signal and an opposite phase signal are added to the signal from the overvoltage applying device 4 in synchronization with the fall of the transmission signal,
The signal is output to the drive circuit 6 as a signal as shown in FIG.

The drive circuit 6 amplifies the signal input from the reverse excitation applicator 5 with a predetermined gain and outputs the amplified signal to the ultrasonic transducer as a drive signal. Thus, the ultrasonic signal output from the ultrasonic transducer 7 has a signal waveform as shown in FIG.

The reason why the modulation signal is modulated by the overvoltage applying unit 4 and the reverse excitation applying unit 5 is as follows. That is, the start of oscillation in the ultrasonic vibrator 7 depends on the drive voltage. Therefore, when a pulse signal having a large peak value is added by the overvoltage applicator 4, the ultrasonic vibrator 7 starts oscillating quickly due to the added pulse signal, and a signal generated at a rising portion of the emitted ultrasonic signal. Of dripping becomes small.

On the other hand, the reverberation characteristic of the ultrasonic vibrator 7 causes a dripping of the signal at the falling part of the ultrasonic signal. However, the reverse excitation applicator 5 cancels the reverberation characteristic so that the signal has an opposite phase to the modulation signal. Is added, so that the sag of the signal generated at the falling portion of the ultrasonic signal is suppressed.

The overvoltage applicator 4 and the reverse excitation applicator 5
The peak value and the number of pulses of the pulse signal to be added or added in are appropriately set according to the characteristics of the ultrasonic transducer 7 to be used and the like.

For example, it is preferable that the peak value of the pulse signal to be added in the overvoltage applicator 4 is set to about 1.5 times the peak value of the modulation signal, and that the number of pulses be 2 pulses. Preferably, the peak value of the pulse signal to be added is set to a peak value equal to the peak value of the modulation signal, and the number of pulses is set to 2 pulses.

The arrangement order of the overvoltage applicator 4 and the reverse excitation applicator 5 described above may be such that a signal from the reverse excitation applicator 5 is input to the overvoltage application apparatus 4.

In the above description, the signal to be added by the overvoltage applicator 4 is synchronized with the rise of the transmission signal, and the signal to be added by the reverse excitation applicator 5 is synchronized with the fall of the transmission signal. The case of adding has been described.
This is based on the premise that the transmitted signal is of positive logic, and when the transmitted signal is of negative logic, the overvoltage applicator 4 synchronizes with the falling edge of the transmitted signal, 5
Then, the above-described processing such as signal addition may be performed in synchronization with the rise of the transmission signal.

Further, as a method of partially increasing the peak value of the modulation signal, a method of amplifying a corresponding pulse of the modulation signal is also possible.

As an example of implementing such a method, a multiplier (analog multiplier) is used as the head area pulse changing means, and a modulation signal is input to the multiplier. Then, by inputting a predetermined voltage from the multiplier input side,
It is possible to make the peak value dependent on the voltage. In this case, it is necessary to appropriately set the voltage application time and increase the peak value only for the pulse in the desired leading region.

As another example, a switch circuit having two inputs and one output is used for the head area pulse changing means, a modulation signal is input to one input terminal, and a pulse signal having a desired peak value is input to the other input terminal. When the modulation signal is input, the switch is switched for a predetermined time to output a pulse signal having a desired peak value, and otherwise, the modulation signal may be output.

As described above, since the rise and fall of the ultrasonic signal are corrected by the overvoltage applying device and the reverse excitation applying device, the data output rate of the ultrasonic signal can be increased.

A second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a configuration block diagram of the ultrasonic signal generator according to the present embodiment.

The ultrasonic signal generator is provided with a carrier oscillator 1 for generating a carrier signal, a transmission signal generator 2 for generating a transmission signal, a carrier signal and a transmission signal, and the transmission signal is converted to a carrier signal. A digital signal processor 8 that performs modulation and performs predetermined signal processing and outputs a signal, a digital / analog converter (D / A converter) 9 that converts a signal from the digital signal processor 8 into an analog signal,
It has a drive circuit 6 for amplifying a signal from the A converter 9 with a predetermined gain, and an ultrasonic vibrator 7 for emitting an ultrasonic signal by a signal from the drive circuit 6.

The digital signal processor 8 includes a pulse modulator 8a for pulse-modulating a transmission signal with a carrier signal and outputting the modulated signal as a modulation signal, which is included in the leading area of the modulation signal in synchronization with the rise of the transmission signal. An overvoltage applying section 8b, which is a head area pulse changing means for setting the peak value of the pulse to a predetermined peak value; Reverse excitation applying section 8c which is a rear area pulse changing means added to the signal
have.

With the above configuration, the carrier signal from the carrier oscillator 1 and the transmission signal from the transmission signal generator 2 are input to the digital signal device 8.

In the digital signal processing device 8, the transmission signal is modulated by the carrier signal from the carrier oscillator 1 by the pulse modulator 8b. Then, a signal larger than the peak value of the modulation signal by a predetermined amount is added by the overvoltage application section 8b to the modulation signal in synchronization with the rise of the transmission signal, and synchronized with the fall of the transmission signal by the reverse excitation application section 8c. Overvoltage applying section 8
An inverted phase signal is added to the signal from b, and the signal is output to the D / A converter 9 as a signal as shown in FIG.

The signal analog-converted by the D / A converter 9 is input to the drive circuit 6, amplified to a predetermined level by the drive circuit 6, and output to the ultrasonic vibrator 7 as a drive signal.

The peak value and the pulse number of the pulse signal added or added in the overvoltage applying section 8b and the reverse excitation applying section 8c are appropriately set according to the characteristics of the ultrasonic vibrator 7 to be used.

For example, it is preferable that the peak value of the pulse signal to be added in the overvoltage applying unit 8b is set to about 1.5 times the peak value of the modulation signal, and that the number of pulses be 2 pulses. It is preferable that the peak value of the pulse signal to be added be a peak value equal to the peak value of the modulation signal, and the number of pulses be two pulses.

The arrangement order of the overvoltage applying section 8b and the reverse excitation applying section 8c described above may be such that a signal from the reverse excitation applying section 8c is input to the overvoltage applying section 8b. In this case, the digital signal processing device can be realized by a digital signal processor, and in such a case, there is an advantage that only the processing procedure needs to be replaced.

In the above description, the signal to be added in the overvoltage applying section 8b is performed in synchronization with the rise of the transmitted signal, and the signal to be added in the reverse excitation applying section 8c is synchronized in synchronization with the falling of the transmitted signal. The case of adding has been described. This is based on the premise that the transmitted signal is of a positive logic. When the transmitted signal is of a negative logic, the overvoltage applying unit 8b synchronizes with the falling edge of the transmitted signal and the reverse excitation applying unit In step 8c, the above-described processing such as signal addition may be performed in synchronization with the rise of the transmission signal.

Further, as a method of partially increasing the peak value of the modulation signal, a method of amplifying a corresponding pulse of the modulation signal is also possible.

As an example of implementing such a method, a multiplier (analog multiplier) is used as the head area pulse changing means, and a modulation signal is input to the multiplier. Then, by inputting a predetermined voltage from the multiplier input side,
It is possible to make the peak value dependent on the voltage. In this case, it is necessary to appropriately set the voltage application time and increase the peak value only for the pulse in the desired leading region.

As another example, a two-input one-output switch circuit is used for the head area pulse changing means, a modulation signal is input to one input terminal, and a pulse signal having a desired peak value is input to the other input terminal. When the modulation signal is input, the switch is switched for a predetermined time to output a pulse signal having a desired peak value, and otherwise, the modulation signal may be output.

As described above, since the rise and fall of the ultrasonic signal are corrected by the digital signal processing device, the data output rate of the ultrasonic signal can be increased.

[0047]

According to the present invention, the pulse signal having a predetermined peak value is added to the head area of the modulation signal by the head area pulse changing means, and the ultrasonic vibrator is rapidly oscillated. The sag of the signal generated at the rising part of the ultrasonic signal is reduced, and the modulation signal and the signal of the opposite phase are added by the tail area pulse changing means so as to cancel the reverberation characteristic of the ultrasonic vibrator. Since the sag of the signal generated at the falling portion of the ultrasonic signal is suppressed, the transmission rate of the ultrasonic signal can be increased, and the sag of the ultrasonic signal need not be considered in the design. .

[Brief description of the drawings]

FIG. 1 is a block diagram of an ultrasonic signal generator applied to the description of a first embodiment of the present invention.

FIG. 2 is a diagram showing signal waveforms output from respective blocks of the ultrasonic signal generator in FIG.

FIG. 3 is a block diagram of an ultrasonic signal generator applied to the description of a second embodiment of the present invention.

FIG. 4 is a block diagram of an ultrasonic signal generator applied to the description of the conventional technique.

5 is a diagram showing waveforms of signals output from respective blocks of the ultrasonic signal generator in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 carrier oscillator 2 transmission signal generator 3 pulse modulator 4 overvoltage applicator 5 reverse excitation applicator 6 drive circuit 7 ultrasonic transducer 8 digital signal processor 9 digital / analog converter

Claims (2)

[Claims] 1. A carrier signal generator for generating a carrier signal composed of continuous pulses, a transmission signal generator for generating a transmission signal as an information signal, and the carrier signal for converting the transmitted signal from a plurality of pulses. A pulse modulator for modulating the modulated signal, a leading area pulse changing means for providing a pulse having a peak value larger than the peak value of the pulse for a predetermined number of pulses from the leading pulse of the modulated signal, Following the tail pulse, a tail region pulse changing means for adding a pulse having a phase opposite to that of the modulation signal, and a signal obtained by partially changing the modulation signal by the head region pulse changing means and the tail region pulse changing means. An ultrasonic signal generator comprising: a drive circuit that amplifies with a gain of (1) and an ultrasonic vibrator that emits an ultrasonic wave based on a signal from the drive circuit. 2. A carrier signal generator for generating a carrier signal composed of continuous pulses, a transmission signal generator for generating a transmission signal as an information signal, and the carrier signal for converting the transmitted signal from a plurality of pulses. A pulse modulating unit for modulating the modulated signal, a leading area pulse changing unit for providing a pulse having a peak value larger than the peak value of the pulse for a predetermined number of pulses from the leading pulse of the modulated signal, A digital signal processor including a tail pulse changing unit for adding a pulse having an opposite phase to the modulation signal following the tail pulse; and a digital / analog converter for converting a signal from the digital signal processor into an analog signal. , A drive circuit for amplifying a signal from the digital / analog converter with a predetermined gain, and emitting ultrasonic waves based on the signal from the drive circuit An ultrasonic signal generator comprising an ultrasonic vibrator.