JPS61145470A - Ultrasonic range finder - Google Patents

Abstract

PURPOSE:To measure an approach distance with high accuracy, by providing a frequency divider which divides the frequency of a reference pulse and receives the control of a frequency dividing ratio by the definite figure-up output of a counter. CONSTITUTION:The transmission pulse transmitted from a transmission circuit 2 is applied to an ultrasonic sensor 1 and an ultrasonic wave is transmitted to an article 9 to be measured while the ultrasonic pulse reflected from the article 9 to be measured is amplified and detected by a receiving circuit 3. When the output of said circuit 3 exceeds reference voltage, an output pulse is generated in an amplitude comparing circuit 4. The transmission pulse of the circuit 2 and the output pulse of the circuit 4 are respectively inputted to a gate circuit 5 to determine the start and stop timings of the gate pulse. The gate pulse generated in the circuit 5 is added to a counter 6 to control the operation of the counter 6. The reference pulse generated from a reference pulse generation circuit 7 receives frequency dividing by a frequency divider 10 to be inputted to the counter 6 and a frequency dividing ratio is controlled by the figure-up output from the counter 6 outputted when the count number of the counter 6 became larger than a preset value.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ultrasonic distance measuring device that measures distance by measuring the propagation time of ultrasonic pulses.

2. Description of the Related Art Recently, ultrasonic distance measuring devices have come to be widely used in fields such as assembly robots, painting robots, and liquid level meters.

As this conventional ultrasonic distance measuring device, the configuration described, for example, in Ultrasonic Technology Binken (Nikkan Kogyo Shimbun), page 760 is known, and its outline will be explained with reference to FIG. 2. Reference numeral 101 denotes an ultrasonic sensor that transmits and receives ultrasonic pulses to and from the object to be measured 109, and a transmission pulse generated by a transmission circuit 102 is applied to this ultrasonic sensor 1o1. The ultrasonic pulse transmitted by the ultrasonic sensor 101 is reflected by the object to be measured 109, and the ultrasonic pulse is transmitted to the ultrasonic sensor 10 again.
The received signal reaching 1 is subjected to signal processing such as amplification and detection by the receiving circuit 103.

When the output of the receiving circuit 103 exceeds the reference voltage vT, the amplitude comparison circuit 104 generates an output pulse, and this output pulse is input to the gate circuit 105, which determines the timing of stopping the gate pulse. Furthermore, the transmission pulse generated in the transmission circuit 102 is also input to the gate circuit 105, which determines the start timing of the gate pulse.

A gate pulse generated in gate circuit 106 is applied to counter 106 to control the operation of counter 106. That is, the reference pulse generated by the reference pulse generation circuit 107 is counted by the counter 106 only for a period determined by the gate pulse. The count number of this reference pulse is converted into the distance d between the ultrasonic sensor 101 and the object to be measured 109 by the distance calculating circuit 108.

Therefore, since distance measurement accuracy depends on the frequency of the reference pulse, it is necessary to use a reference pulse with a high frequency in order to improve the accuracy.

Problems to be Solved by the Invention However, in the conventional configuration like the one described above, the same reference pulse frequency is used from close distance to long distance. When using a frequency reference pulse, the counter 106
There is a problem in that the count number becomes large, and therefore the scale of the counter 106 and the distance calculation circuit 108 becomes large.

On the other hand, when a low frequency reference pulse is used to reduce the count number, there is a problem that the distance measurement accuracy deteriorates.

SUMMARY OF THE INVENTION Therefore, the present invention aims to provide an ultrasonic distance measuring device that can measure close distances with high precision and also eliminates the need to increase the scale of the counter and distance calculation circuit even at long distances. be.

Means for solving the problems and technical means of the present invention for solving the above problems include an ultrasonic sensor that transmits and receives ultrasonic pulses to and from an object to be measured, and a transmitting signal to the ultrasonic sensor. A transmitting circuit that applies voltage, a receiving circuit that processes the received signal from the ultrasonic sensor, an amplitude comparison circuit that compares the amplitude of the output of this receiving circuit, and a gate pulse that is applied to the output of the transmitting circuit using the output of the amplitude comparison circuit. A gate circuit that generates a gate circuit, a counter whose operation is controlled by the output of this gate circuit, a reference pulse generation circuit that generates a reference pulse to be input to this counter, a reference pulse generator that divides the frequency of the reference pulse, and carries the counter by a certain number of digits. This device is equipped with a frequency divider whose frequency division ratio is controlled by the output, and a distance calculation circuit which converts the output from the counter into distance.

Operation According to the above-described configuration, the transmission pulse generated by the transmission circuit is applied to the ultrasonic sensor, and the ultrasonic sensor sends the ultrasonic wave to the object to be measured.

The ultrasonic pulse reflected by the object to be measured is received by the ultrasonic sensor, and this received signal is processed by the receiving circuit. When the output of this receiving circuit exceeds the reference voltage, the amplitude comparison circuit generates an output pulse. The transmission pulse generated by the transmission circuit is input to the gate circuit to determine the start timing of the gate pulse, and the output pulse generated by the amplitude comparison circuit is input to the gate circuit to determine the stop timing of the gate pulse. A gate pulse generated in this gate circuit is applied to a counter and controls the operation of this counter. The reference pulse generated by the reference pulse generator is frequency-divided by the divider and then input to the counter. The frequency division ratio of the frequency divider is controlled by the output at a certain digit of this counter, and when there is an output,
Divide the reference pulse to a lower frequency by increasing the division ratio,
When there is no output, the division ratio is reduced to divide the frequency of the reference pulse to a higher frequency than when there is output.

Therefore, it is possible to measure close distances with high precision, and when measuring long distances, there is no need to increase the scale of the counter and distance calculation circuit.

EXAMPLE Hereinafter, an example of the present invention will be described in detail with reference to the drawings. In FIG. 1, 1 is an ultrasonic sensor that transmits and receives ultrasonic pulses to and from an object to be measured 9, 2 is a transmitter circuit that generates a transmission pulse to be applied to the ultrasonic sensor 1, and 3 is the object to be measured by the ultrasonic sensor 1. This is a receiving circuit that performs signal processing such as amplification and detection of the received signal received from the object 9. 4 is an amplitude comparison circuit that compares the amplitude of the output of the receiving circuit 3 and generates an output pulse when the output exceeds the reference voltage VT; 6 is the transmitting circuit 2;
The start timing is determined by the transmitted pulse of
a gate circuit 6 whose strip timing is determined by the output pulse of the amplitude comparison circuit 4 and which generates a gate pulse;
is a counter (for example, a binary counter) whose operation is controlled by the output of the gate circuit 5. 7 is a reference pulse generation circuit that generates a reference pulse to be input to the counter 6; 1o is a frequency divider that divides the reference pulse and the division ratio is controlled by the carry output of a certain digit of the counter; 8 is a frequency divider that divides the frequency of the reference pulse; The output from the counter 6 connects the ultrasonic sensor 1 and the object to be measured 9.
This is a distance calculation circuit that converts the distance d to the distance d.

Next, the operation of the above embodiment will be explained. A transmission pulse generated by the transmission circuit 2 is applied to the ultrasonic sensor 1, and the ultrasonic sensor 1 sends an ultrasonic wave to the object to be measured e. The ultrasonic pulse reflected by the object to be measured 9 is received by the ultrasonic sensor 1, and this received signal is subjected to signal processing such as amplification and detection by the receiving circuit 3. The output of this receiving circuit 3 is the reference voltage v
When T is exceeded, the amplitude comparator circuit 4 generates an output pulse.

The transmission pulse generated by the transmission circuit 2 is input to the gate circuit 5 to determine the start timing of the gate pulse, and the output pulse generated by the amplitude comparison circuit is input to the gate circuit 5 to determine the timing to stop the gate pulse. be done. A gate pulse generated in this gate circuit 5 is applied to a counter 6 to control the operation of this counter 6.

The reference pulse generated in the reference pulse generation circuit 7 is frequency-divided by the frequency divider 10 and then input to the counter 6. The division ratio is controlled by a carry output from the counter 6 when the count number in the counter 6 becomes larger than a preset value. Further, the carry output is input to a distance calculating circuit 8, which determines a conversion formula for converting the count number of the counter 6 into a distance. The value DS preset in the counter 6 can be, for example, a numerical value in which the most significant bit of the counter 6 becomes 1 for the first time. The distance corresponding to this set value Ds is assumed to be dll(m).

When this ultrasonic distance measuring device is operated at a measurement distance d (m/) of
The frequency division ratio of 0 is set to 1. When the count number of this Ibis base fishing pulse is smaller than the set value Ds, that is, d(d
, the count number is directly converted into distance by the distance calculation circuit 8 and output. Next, the measurement distance d is ds≦d<2
For d and l, the reference pulse count is the set value Ds
Therefore, the frequency divider 10'f is controlled by the carry output of the counter 6 when the set value Ds is exceeded, and the frequency division ratio is set to 1/2, and the carry output is sent to the distance calculation circuit 8. is also input, and the conversion formula 1d for converting the count number of the counter 6 to distance is controlled so that the relationship is twice that of the case of dB.The carry pulse is also input to the transmitting circuit 2, and the carry pulse is input to the ultrasonic sensor. Apply a transmission pulse to 1 and repeat the transmission/reception operation.Also, when there is a certain carry output of the counter, the calculation result in the distance calculation circuit is cleared and no output is performed.Furthermore, if the measured distance is large, 2ds ≦d
When <4ds, the count number of the reference pulse divided into 1/2 exceeds the set value Dswo again in the counter 6,
A carry pulse is output. The frequency divider 10 is controlled by this carry output, and the division ratio is set to 1/4. The carry output is also input to the distance calculation circuit 8, and is controlled so that the relationship is four times that of the conversion formula 1d (d) for converting the count number of the counter 6 to distance. The pulse is input to the transmitting circuit 2, which applies the transmitting pulse to the ultrasonic sensor 1, and repeats the transmitting and receiving operation.If the measurement distance is further large, the counter 6's turn 1/1 is
6, 1/32..., and at the same time, the conversion formula for converting the count number in the distance calculation circuit 8 into distance is d.
<8 times, 16 times, 32 times compared to ds...
・It is controlled so that The measured distance is the value when there is no carry output from the counter 6. Further, the carry pulse is input to the transmitting circuit 2, which applies the transmitting pulse to the ultrasonic sensor 1, and repeats the transmitting and receiving operation.

When there is a carry output for the set value Ds of the counter 6, the transmission operation is repeated (carry count + 1) times to perform one distance measurement, and the distance is calculated based on the counter output when no carry output occurs. be done.

Naori counter 6 does not need to be a binary counter,
Generally, when using an N-ary power counter, if the number of carries of the counter is im, the frequency division ratio of the frequency divider may be set to (1/N)m. Further, the relationship between the count number and distance conversion in the distance calculation circuit 8 may be multiplied by 8 m compared to the case where the frequency division ratio is 1.

As described above, according to the above embodiment, when the measurement distance is small, the reference pulse is not frequency-divided and is used as a high frequency as a counter input. Therefore, the measurement distance corresponding to one counter of the counter 6 is small, and it is possible to measure the distance with high accuracy. Further, when the measurement distance becomes large, the frequency of the reference pulse is divided, so distance measurement can be performed without increasing the scale of the counter or the distance calculation circuit. As a result, as the measured distance becomes larger, the measured distance corresponding to one count of the counter 6 becomes smaller.
Distance measurement accuracy becomes coarser, but in general, the closer the distance, the more accurate measurement is required, and at longer distances, coarse measurement is often enough and there are few problems.

Effects of the Invention As is clear from the above explanation, according to the present invention, the division ratio of the frequency divider is controlled by the output at a certain digit of the counter, and when there is an output, the division ratio is increased and the reference pulse is When there is no output, the frequency division ratio is made small so that the frequency of the reference pulse is divided to a higher frequency than when there is output. Therefore, it is possible to measure close distances with high precision, and when measuring long distances, there is no need to increase the scale of the counter and distance calculation circuit.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the ultrasonic distance measuring device of the present invention, and FIG. 2 is a block diagram of a conventional ultrasonic distance measuring device. 1... Ultrasonic sensor, 2... Transmission circuit, 3... Receiving circuit, 4... Amplitude comparison circuit, 5... Gate Circuit, 6...Counter, 7...Reference pulse generation circuit, 8...
・Distance calculation circuit, 9...Object to be measured, 1o...
...Divider.

Claims (5)

[Claims] (1) An ultrasonic sensor that transmits and receives ultrasonic pulses to and from an object to be measured, a transmitting circuit that applies a transmitting signal to this ultrasonic sensor, a receiving circuit that processes the received signal from the ultrasonic sensor, and this receiving circuit. An amplitude comparison circuit that compares the amplitude of the output of the circuit, a gate circuit that generates a gate pulse based on the output of the above-mentioned transmitting circuit and the output of the amplitude comparison circuit, a counter whose operation is controlled by the output of this gate circuit, and an input to this counter. A reference pulse generation circuit that generates a reference pulse for the purpose of the test, a frequency divider that divides the reference pulse and whose division ratio is controlled by a constant carry output of the counter, and a distance calculation that converts the output from the counter into distance. An ultrasonic distance measuring device characterized by comprising a circuit. (2) When the number of carry outputs of a certain digit of the counter is m times for the reference pulse generated in the reference pulse generation circuit and input to the counter through the frequency dividing circuit, and the counter is made into an N-ary power counter. , the frequency division ratio of the frequency divider is (1/N)m
An ultrasonic distance measuring device according to claim 1, wherein: (3) When the number of carry outputs of a certain digit of the counter is m times with respect to the reference pulse generated in the reference pulse generation circuit and input to the counter through the frequency dividing circuit, and the counter is an N-ary counter, The ultrasonic distance measuring device according to claim 1, wherein the conversion relationship for converting the counter output into distance in the distance calculation circuit is (N)^m. (4) When there is a carry output of a certain digit of the counter,
The ultrasonic distance measuring device according to claim 1 or 3, wherein the calculation result in the distance calculation circuit is cleared and not outputted. (5) The ultrasonic distance measuring device according to claim 1, wherein the transmitting circuit transmits data every time a carry is output in response to a carry output of a predetermined digit of the counter.