JPS60140168A - Ultrasonic distance measuring apparatus - Google Patents

Abstract

PURPOSE:To enable the measurement of distance in a wide range from the close to far range by controlling the number of waves of a transmission pulse corresponding to the distance to be measured with an output signal of a time measuring section for measuring time between respective pulses received and transmitted. CONSTITUTION:A transmission pulse is applied to an ultrasonic sensor 3 from a transmission circuit 2 and the pulse reflected from an object to be measured received with the ultrasonic sensor 3. Then, the pulse is amplified and detected with a receiving circuit 4 and compared with the reference voltage by a comparator circuit 5 to generate an output pulse according to being smaller or larger than the reference voltage. Then, a pulse is generated with a time measuring circuit 6 with the length corresponding to time between the transmitted pulse and the received pulse, namely, the proparation time between the transmission and reception of the ultrasonic pulse. Corresponding to the output of the circuit 6, a number of waves controlling circuit 10 regulates the gate pulse according to distance to be measured to control the number of waves of the transmission pulse.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ultrasonic distance measuring device.The configuration of a conventional example and its problemsThe configuration of a conventional ultrasonic distance measuring device is illustrated in FIG.

1 is a gate pulse generation circuit that generates a gate pulse that controls the wave number of the transmission pulse applied to the ultrasonic sensor 3, and also generates a measurement start pulse for the time measurement circuit 6 in synchronization with the generation of the gate pulse; 2 is a transmission ( A transmitting circuit that applies Fl pulses to the ultrasonic sensor 3, 4 is an object to be measured (not shown)
The ultrasonic pulse reflected by the ultrasonic sensor 3
A receiving circuit that amplifies and detects the output after receiving the wave at
6 is a comparison circuit that compares the output voltage of the receiving circuit with a reference voltage and generates an output pulse depending on the magnitude of the output voltage and the reference voltage. 6 is the time between the transmitted pulse and the received pulse, that is, the ultrasonic pulse propagation. This is a time measurement circuit that measures time, and measures the time interval from the start pulse generated by the gate pulse generation circuit 1 to the output pulse of the comparison circuit 6. 7 is a time/distance conversion circuit, as described above. Convert the measured time to distance using a certain relational expression.

Figure 2 shows the waveforms of each part of the ultrasonic distance measuring device configured as described above. In Figure 2, a is game]
The gate pulse generated by the pulse generation circuit 1 determines the wave number of the transmission pulse, b is the transmission pulse applied to the ultrasonic sensor 3, C is the reception waveform received by the reception circuit 4, and 8 is the reception waveform from the transmission circuit 2. These are the leakage waveform of the transmission signal to the receiving circuit 4 and the reflected waveform from the 9th L measured object. d is the waveform after detection and rectification of the leaky wave and reflected wave in the receiving circuit 4, and e is the waveform after the detected and rectified waveform d is detected and rectified in the comparator circuit 6. This is an output pulse that is generated when the amplitude is greater than the reference voltage EsJ, and the time interval To from the 1-input part of the sending pulse b is 3 degrees, which corresponds to the measurement distance. Since the pulse response characteristics of the ultrasonic sensor 3 were insufficient, in order to use the ultrasonic sensor 3 with the transmission amplitude completely raised to the saturation amplitude, it was necessary to It is necessary to drive the sensor 3, and it has been difficult to make the duration Td of the leakage wave 8 shown in FIG. 2C sufficiently short. Therefore, if the object to be measured exists at such a close distance that the reflected wave 9 is received within the duration time Td of the leaky wave 8, the reflected wave 9 and the leaked wave 8 are separated from each other on the time axis as shown in FIG. This has the problem that the distance measurement becomes difficult due to the overlapping of the two objects. On the other hand, when the wave number of the transmitted pulse is reduced so that the reflected wave 9 and the leaked wave 8 do not overlap on the time axis to enable close distance measurement, the transient response characteristics of the ultrasonic sensor 3 are insufficient. , the transmission amplitude of the ultrasonic sensor 3 does not rise to the saturation amplitude rlJvs when the wave number of the transmission pulse shown in No. 4 Na is sufficiently large, but becomes a small amplitude compared to the saturation amplitude Vs as shown in Fig. 4. 11]
This method has a problem in that it is difficult to obtain a large measurement distance because VL cannot be obtained.

Purpose of the Invention The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to enable distance measurement using an ultrasonic distance measuring device over a wide range from close distances to long distances. It is something.

Structure of the Invention The present invention achieves the above object, and includes an ultrasonic sensor,
a transmitter that applies a transmit pulse to the ultrasonic sensor; a receiver that receives the ultrasonic reflected pulse from the object to be measured; a comparator that compares the output voltage of the receiver with the base q constant voltage; and a time-distance conversion unit that converts the propagation time measured by the 11i'1 measurement unit into a distance, and the output of the time measurement unit The present invention provides an ultrasonic distance measuring device characterized by comprising a wave number control section that controls the wave number of the transmission pulse of the transmitting section.

Description of examples Examples of the present invention will be described below using FIG.

FIG. 6 shows ultrasonic iI! in one embodiment of the present invention! 1gj
FIG. 2 shows a block diagram of the poultry IFill+ stationary device.

In the figure, 2 is a transmitting circuit, 3 is an ultrasonic probe, 4 is a receiving circuit, 5 is a comparison circuit, 6 is an h-interval start-up circuit, 7 is a time-distance conversion circuit, and 10 is the output of the time measurement circuit 6. Measurement 11. with a wave number control circuit for controlling the wave number of the transmitted pulse using a corresponding signal. When '11ii1 is short, that is, when the measurement distance is short, shorten the gate palace and adjust the wave number of the transmitted pulse. When the measurement time is long, that is, the measurement distance is long, the gate pulse is lengthened to increase the wave number of the transmitted pulse.

An embodiment of the wave number control circuit 10 is shown in FIG. 6, and waveforms of various parts are shown in FIG. 6 measures the time between the transmitted pulse and the received pulse (it is a distance measuring circuit, which generates a pulse with a length corresponding to the propagation time To between the transmitting and receiving pulses of the ultrasonic pulse as shown in Fig. 7a). an integrating circuit of the control circuit 10;
Peak hold circuit 11 and gate pulse generation circuit 1
After integrating the output pulse of the time measuring circuit 6 (Fig. 7a), the peak value (Fig. 7b) is held in the peak hold circuit 11, and the gate pulse is generated using the held voltage value. By setting the constant that determines the pulse length of the circuit 12 to 1, the gate pulse length is changed and the wave number of the transmission pulse is set to 1 on the open side. Here, the constant that determines the gate pulse length is, for example, the volume of the capacitor/cell C,
By using a burr gap, it is possible to change the capacitance u1 according to the voltage, and therefore the propagation of ultrasonic waves [Pl-, that is, the Gehle length can be changed depending on the measurement distance]. 1] Become Noh.

A second embodiment of the wave number control circuit 10 is shown in FIG. 8, and waveforms at various parts are shown in FIG. 9.

6 is a time measurement circuit, which generates a pulse having a length corresponding to the propagation time T (1) between the transmitter and receiver of the ultrasonic pulse as shown in Fig. 9. Comparator 137 tsubo stable multi-by break 14
．． The transmission timing signal consists of a pulse generation circuit 16 and an AND gate 16.The integrated waveform (Fig. 9C) of the output pulse of the time measurement circuit 6 (Fig. 9B) is manually obtained.
, the output of the level comparator 13 when lr (res()
TB 9 Figure d) (7)? & T for a certain period of time using the edges
A monostable multivibrator 14 that generates .zeta.notos with a length of 1 is operated.

The output voltage of the monostable multivibrator 14 is a pulse width Tp7i1. with a repeating Itd period of length T1 (see FIG. 9, 6) and Ts. Lua, (i9
It is set so that it has a part that is 1 tatami in time with Figure a). The transmission timing pulse (FIG. 9a) is generated by the transmission timing pulse generation circuit 16 in FIG.

Next, the output pulse of the monostable multivibrator 14 (9th
By manually inputting the transmission timing and transmission timing Z) (FIG. 9a) to the computer game 1.16, a pulse width T27z shown in FIG. 9F can be obtained.

By using this pulse as a transmission gate pulse, it is possible to control the wave number of the transmission pulse. When the measurement distance is large, the pulse width T2 becomes long, and when the measurement distance is small, the pulse width T2 is short. It is possible to do this.

In this embodiment, by adjusting the wave number of the transmitted h pulse according to the measurement distance, it becomes possible to accurately measure distances over a wide range from close distances to long distances.

Effects of the Invention In summary, the present invention includes an ultrasonic sensor, a transmitting section that applies a transmitting pulse to the ultrasonic sensor, a receiving ear section that receives ultrasonic waves reflected from an object to be measured; a comparison section that compares the output voltage of the receiving section and a reference voltage serially and crosswise; a time measuring section that measures the interval between the transmitting pulse and the receiving bus A/S; The ultrasonic wave is characterized by comprising: a time-distance conversion section that converts the propagation time into a distance; and a wave number control section 11 that controls the wave number of the transmission pulse of the transmitter based on the output signal of the time measurement section. This device provides a distance measuring device that controls the wave number of the transmitted pulse using the output (M"kj'%) corresponding to the measurement tolerance level 1. The smaller the measurement distance is, the lower the wave number of the transmitted pulse is. I see, since it is possible to increase the number of waves for each response (transmission), the measurement range of the ultrasonic distance measuring device can be extended from close distance to l['1jllf
It can be set in a wide range.

[Brief explanation of drawings]

Figure 1 shows the 1fJi block diagram of a conventional ultrasonic distance measuring device.
FIG. 3 is an explanatory diagram of leakage waves and reflections of transmitted pulses, C las and A las response characteristics, FIG. 6 is a block diagram of the configuration of an ultrasonic distance measuring device according to an embodiment of the present invention, 6 is a block diagram showing the first embodiment of the wave number control circuit, which is the main part of the present invention. FIG. 7 is a block diagram showing the first embodiment, and FIG. 9 is a block diagram showing the second embodiment. 5 is a timing chart showing waveforms of various parts in an example. 2-...Transmission circuit, 3...Ultrasonic sensor, 4...Reception circuit, 6--Comparison circuit, 6-One hour measurement circuit, 7
...Time-distance conversion circuit, 1o...-wave number control circuit,
11-・Peak hold circuit, 12・・Gate pulse generation circuit, 13・Level comparator, 14・
・Monostable multivibrator, 16 ・Transmission timing pulse generation circuit, 16...-ant gate. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Figure 2 Figure 3 (2) Figure 4 Figure 5 Figure 4 5 6 7 Figure 6 Figure 7 Figure 8 Figure 1θ / 5 Figure 9 Back Tz

Claims (1)

[Scope of Claims] (1) An ultrasonic sensor, a transmitter that applies a transmission pulse to the ultrasonic sensor, a receiver that receives an ultrasonic reflected pulse from an object to be measured, and an output voltage of the receiver. and a reference voltage; a time measurement unit that measures the time between the transmitted pulse and the received pulse; and a time-distance conversion unit that converts the propagation time measured by the time measurement unit into distance; An ultrasonic distance measuring device comprising: a wave number control section that controls a wave number of a transmission pulse of the transmitting section based on an output signal of the time measuring section. (The first claim is characterized in that the wave number control unit is controlled so that the longer the propagation time of the ultrasonic pulse measured by the time measurement unit, the greater the wave number of the transmitted pulse.
The ultrasonic distance measuring device described in . and a gate pulse generating circuit, and the pulse length of the first pulse generating circuit is configured to be equal to 1 ml+ by the output of the peak hold circuit connected to the integrating circuit. The ultrasonic distance measuring device according to item 1 or 2. (4) The wave number control unit includes an integrating circuit, a level comparator, a monostable multi-vibration whose oscillation timing is controlled by the output pulse of the level comparator, and a transmission timing pulse generator that generates a pulse that gives the repetition period of the ultrasonic pulse. 1. A circuit according to claim 1, comprising: a circuit; and an ant game 1 for calculating the logical sum of the output of the monostable multi-by-break and the pulse from the transmission timing pulse generation circuit. Ultrasonic distance measuring device.