JPS61251781A - Ultrasonic distance measuring instrument - Google Patents

Abstract

PURPOSE:To measure the distance to an object of measurement with good response and precision by generating a saw-tooth wave in synchronism with the transmission timing of an ultrasonic wave and sampling the saw-tooth wave in synchronism with the reception timing of a reflected wave. CONSTITUTION:The saw-tooth wave signal TW is made to rise in synchronism with the transmission timing of the ultrasonic wave pulse signal SW and the signal TW is sampled as a distance detection signal DS with sampling pulses SP synchronized with the reception timing of the reflected wave EW of the ultrasonic wave. The signal DS is proportional to the distance to the object 4 of measurement and a distance measurement is taken on the basis of the signal DS. Further, the signal DS is obtained by sampling the signal TW, so it is updated in every cycle of the transmission period of the signal SW and the distance to the object of measurement is therefore measured with good response.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic distance measuring device, and particularly to a voltage output type ultrasonic distance measuring device.

[Conventional technology]

Conventionally, various distance measurement methods have been used to measure the distance to the measurement target, but among these methods, the method using ultrasonic waves has been adopted because the device can be configured relatively compactly. things are widely used.

A basic configuration example of an ultrasonic distance measuring device using this ultrasonic wave is shown in FIG. In this figure, from the measuring section 1,
A transmission pulse PT (see FIG. 5(a)) with a small duty is output to the ultrasonic oscillator 2 at a predetermined period. As a result, an ultrasonic signal is output from the ultrasonic oscillator 2 during the rising period of the transmission pulse PT, and an ultrasonic wave is sent from the transmitter 3 to the measurement target.

This ultrasonic wave is reflected by the measurement target and received by the wave receiver 4, and the received signal of the receiver 4 is detected and waveform-shaped by the signal processing circuit 5 to produce the received pulse PR (see Fig. 5).
b)) is output to the measurement unit 1.

This measurement unit 1 forms a distance pulse signal PD (see FIG. 5(c)) with a pulse width corresponding to the time from the falling edge of the transmitted pulse PT to the rising edge of the received pulse PR,
Based on the pulse width of this distance pulse signal PD, distance information to the measurement target is formed.

A method of forming distance information based on this distance pulse signal PD includes a method of integrating the distance pulse signal PD to form a level signal corresponding to its pulse width, and outputting this level signal as a distance signal; Gating clock pulses for time measurement using pulse signal PD and counting the number of clock pulses,
There is a method of digital/analog conversion of the counted value to form and output a distance signal.

[Problem that the invention seeks to solve]

However, in the former method of the distance information forming methods described above, it is necessary to set a large time constant of the integral element that integrates the distance pulse signal PD in order to suppress level fluctuations of the distance signal. There was a problem that the responsiveness of distance measurement was poor.

In addition, in the latter method, in order to improve the accuracy of distance measurement, it is necessary to increase the frequency of the clock pulse, which complicates the device configuration of the counting means. / Since it is necessary to use an analog converter with a high conversion speed, there is a problem that the overall cost increases.

[Purpose of the invention]

The present invention solves the problems of the prior art and provides an ultrasonic distance measuring device that has a relatively simple configuration and can measure the distance to a measurement target with good responsiveness and accuracy.
That purpose.

[Means for solving problems]

Therefore, in the present invention, ultrasonic waves are intermittently transmitted to a measurement target at a predetermined period, and reflected waves from the measurement target are received, and the timing between transmitting the ultrasound waves and receiving the reflected waves is adjusted. In the ultrasonic distance measuring device that outputs distance information based on the ultrasonic wave, the ultrasonic distance measuring device includes a sawtooth wave generating means that generates a sawtooth wave in synchronization with the transmission timing of the ultrasonic wave, and a sawtooth wave generation means that generates the sawtooth wave in synchronization with the reception timing of the reflected wave. The apparatus is equipped with a sampling means for sampling waves, and outputs the output of the sampling means as distance information to the measurement target, thereby achieving the above object.

[For production]

Since the sawtooth wave output by the sawtooth wave generating means changes at a constant slope, the level of the sawtooth wave at the time the reflected wave is received depends on the distance from when the ultrasonic wave reaches the measurement target until it returns. Therefore, the level of the sawtooth wave sampled by the sampling means corresponds to the distance to the measurement object.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

As shown in FIG. 1, the ultrasonic distance measuring device according to this embodiment is configured as a transmitter and receiver separated type.

That is, this ultrasonic distance measuring device includes a transmitting section 2 that generates ultrasonic pulses, a receiving section 6 that receives the ultrasonic pulses sent out from the transmitting section 2 and reflected by the measurement object 4,
A measurement control section 8 that performs sampling for distance measurement while controlling the timing of transmission and reception between the transmitter 2 and the receiver 6, and a display section that displays the distance to the measurement target 4 based on the output from the measurement control section 8. It is composed of 10 mag.

In the transmitting section 2, as shown in FIG.
(see figure (a)).

This electric pulse signal SS is applied via an analog switch 12 to a resonant amplifier 13 composed of a transistor, a pulse transformer, etc. in the next stage. This resonant amplifier 13
The electric pulse signal SS whose power is amplified by the transmitter 1
4. In this transmitter 14, an electric pulse signal SS is converted into an ultrasonic pulse signal SW by a transmitting ultrasonic transducer, and this ultrasonic pulse signal SW is sent to the measurement object 4.

Furthermore, within the measurement control section 8, there is constructed a timing signal generator 15 whose main part is an operational amplifier or the like.

The timing signal generator 15 has a duty of 1/10 in order to set the sending timing of the ultrasonic pulse signal SW.
A rectangular wave-like timing signal TS (negative logic; third
(see figure (b)). This timing signal T
S is applied to the control input terminal C of the analog switch 18 via a delay circuit 17 that delays the reception start timing by a predetermined period of time to prevent transmission/reception overlap, and is also applied to the sawtooth wave generator 19 as a drive signal. It is being Further, the timing signal TS is inverted to a timing signal TS' (see FIG. 3(i)) via an analog switch 16. This timing signal TS'
are the negative logic control input terminal C1 of the analog switch 12 of the transmitter 2 and the sawtooth wave generator 19 in the measurement controller 8.
Operational amplifier 19 for setting the operation start timing of
It is applied to the inverting input terminal of A (see Figure 2).

As a result, the ultrasonic pulse signal SW changes from the electric pulse signal SS to the timing signal T, as shown in FIG. 3(c).
It is output intermittently, as if a gate was applied with S.

Further, as shown in FIG. 3(j), the sawtooth wave generator 19 generates a sawtooth wave signal TW whose level increases at a constant slope in synchronization with the falling timing of the timing signal TS'. is output. Furthermore, this sawtooth wave signal TW is applied to a sample and hold circuit 20 that performs sampling using a sampling pulse formed from a reflected wave EW, which will be described later.

On the other hand, the reflected wave EW from the measurement object 4 (Fig. 3(d)
) is received by the transfer device 21 in the receiving section 6. This transfer device 21 is configured similarly to the wave transmitter 14, and converts the reflected wave EW into an electric pulse signal again and outputs it. After this output signal is converted into a current signal R3 by a current converter 22 whose main part is an operational amplifier,
A detection timing window is set by the analog switch 1 in the measurement control section 8 so as not to confuse the timing with the transmission timing of the ultrasonic pulse signal SW for transmission.

Further, the sampling pulse forming means 23 in the measurement control section 8 shapes the waveform of the output signal of the current converter 22 in the receiving section 6 to form a pulse signal for sampling, which will be described later. More specifically, the sampling pulse forming means 23, as shown in FIG.
and a first waveform shaping circuit 26 whose main part is an operational amplifier.
, a differentiating circuit 27 consisting of a resistor, a capacitor, etc., and a second waveform shaping circuit 28 whose main part is an operational amplifier are successively installed in series.

Therefore, the current signal RS is an amplifier! After being amplified by 24, the signal is detected by a detection circuit 25.

The output signal Sl of this detection circuit 25 (see FIG. 3(e))
is further waveform-shaped into a signal S2 (see FIG. 3(f)) by the first waveform shaping circuit 26, and this signal S2 is differentiated by the differentiating circuit 27 to become a signal S3 (see FIG. 3(g)). , this signal S3 is converted into a sampling pulse SP (see FIG. 3(h)) by the second waveform shaping circuit 28.

This sampling pulse SP is applied to an analog switch 20A (see FIG. 2) in the sample & hold circuit 20.
is applied to the control input terminal C of.

Therefore, the sampling pulse SP is
When 0A is applied, the analog switch 20A becomes conductive only during the logic H level of this pulse SP, and the sampling and holding capacitor 20B (see FIG. 2) is charged and discharged. That is, the level of the sawtooth signal TW is sampled at the rising timing of the sampling pulse SP, and the sampling result is sent to the meter circuit of the display unit 10 as the distance detection signal DS (see FIG. 3(j)) via the buffer 20G. etc. is output.

In this way, the sawtooth wave signal TW is raised in synchronization with the ultrasound transmission timing, and this sawtooth wave signal TW is sampled as the distance detection signal DS in synchronization with the reception timing of the ultrasound reflected wave. Therefore,
This distance detection signal DS is proportional to the distance to the measurement target 4, and distance measurement is performed based on this. Moreover, this distance detection signal DS is a sawtooth wave signal TW
Since the signal is obtained by sampling the ultrasonic pulse signal SW, it is updated every cycle of the sending period of the ultrasonic pulse signal SW, and therefore the signal has very good responsiveness. Further, the capacitor 19B (see FIG. 2) in the sawtooth wave generator 19 is charged by constant current charging, and the sawtooth wave signal TW has excellent linearity.

〔Effect of the invention〕

As described above, according to the present invention, there is provided a sawtooth wave generating means that generates a sawtooth wave in synchronization with the transmission timing of ultrasonic waves;
and sampling means for sampling the sawtooth wave in synchronization with the reception timing of the reflected wave caused by the reflection of the ultrasonic wave, and the output of this sampling means is output as distance information to the measurement target, so the configuration is comparable. It is possible to provide an excellent ultrasonic distance measuring device that can simply measure the distance to a measurement target with good responsiveness and accuracy.

[Brief explanation of drawings]

Fig. 1 is a functionalized block diagram showing an ultrasonic distance measuring device according to an embodiment of the present invention, Fig. 2 is a circuit diagram showing the detailed configuration of Fig. 1, and Figs. 3 (a) to j. ) are waveform diagrams for explaining the operation of the device shown in FIGS. 1 and 2, FIG. 4 is a block diagram showing a conventional example of an ultrasonic distance measuring device, and FIGS. 5(a) to c ) is a waveform diagram for explaining the operation of the apparatus shown in FIG. 4. 19 - Sawtooth wave generator as sawtooth wave generating means, 20 - Sample &
Hold circuit, 23.------ Sampling pulse forming means as sampling means. Patent applicant Suzuki Motor Co., Ltd. Figure 3...) Field/Pipe] -i++++++++++++71N]+
＋＋＋＋＋＋＋c2V] 11th sentence ■] 222] Figure 4 Figure 5

Claims (1)

[Claims] Ultrasonic waves are intermittently transmitted to a measurement target at a predetermined period and reflected waves from the measurement target are received, and the timing between transmitting the ultrasound and receiving the reflected waves is In the ultrasonic distance measuring device that outputs distance information based on the ultrasonic waves, the ultrasonic distance measuring device includes a sawtooth wave generating means that generates a sawtooth wave in synchronization with the transmission timing of the ultrasonic wave, and a sawtooth wave generation means that generates the sawtooth wave in synchronization with the reception timing of the reflected wave. An ultrasonic distance measuring device comprising a sampling means for sampling waves, and outputting the output of the sampling means as distance information to a measurement target.