JPS6180082A - Ultrasonic range finder - Google Patents

Abstract

PURPOSE:To facilitate the operation of a distance from the output of a counter, in counting the number of reference pulses between a transmitting pulse and a receiving pulse by an M-stepping counter, by setting the frequency of the reference pulse to the value given by a specific calculation formula. CONSTITUTION:An ultrasonic sensor 1 for transmitting and receiving an ultrasonic wave and a gate circuit 5 generating gate pulses by the transmitting pulse and receiving pulse of said ultrasonic wave are provided. The number of reference pulses outputted between the gate pulses from a reference frequency generation circuit 7 are counted by a counter 6 and the counted value is converted to a distance by a distance operation circuit 8. When an M-stepping counter is used as the counter 6, the frequency f0 of the reference pulse outputted from the reference frequency generation circuit 7 is set so as to satisfy the relation of formula. By this method, the relation between a distance (d) and the number N of pulses comes to d=M<n>.N an operation is facilitated.

Description

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

1. Configuration of conventional example and its problems FIG. 1 shows a block diagram of an ultrasonic distance measuring device which is the basis of the present invention. In FIG. 1, 1 is an ultrasonic sensor that transmits and receives ultrasonic pulses, 2 is a transmission circuit that generates a transmission pulse to be applied to the ultrasonic sensor, and 3 is a wave reflected by an object to be measured 9 and received by the ultrasonic sensor 1. 4 is an amplitude comparison circuit that generates an output pulse when the output of the receiving circuit 3 is equal to or higher than the reference voltage VT; A gate circuit generates a gate pulse using a transmission pulse and an output pulse of the amplitude comparison circuit 4. The gate pulse is applied to the counter 6 to control the operation of the counter 6.

The number of reference pulses generated in the reference frequency generating circuit 7 is counted by a color/counter 6 only during a period determined by the gate pulse. 8 is a distance calculation circuit, which calculates the count number of the reference pulse by the ultrasonic sensor 1.
, converted into a distance between the objects to be measured 9.

FIG. 2 shows the output waveforms in the main parts of FIG. 1. Second
FIG. 4 (4) shows a transmission pulse waveform generated in the transmission circuit 2, (b) shows the output waveform of the reception circuit 3, and vT is a reference voltage in the amplitude comparison circuit 4.

(c) is a gate pulse generated by the transmission pulse applied to the gate circuit 5 and the output of the amplitude comparison circuit 4;
Let this gate pulse width be Tsec.

Here, the reference pulse frequency is fO, the distance between the ultrasonic sensor 1 and the object to be measured 9 is d, the number of reference pulses input to the counter 6 and counted during the period of gate pulse width T is N, If the speed of sound is Vm/sec, the following equation holds true.

Therefore, in order to convert the number of pulses N into the distance d between the ultrasonic sensor 1 and the object to be measured 9, the distance calculation circuit 8 requires the calculation 4=2foxN["]G2), but the counter 6 is In the case of a counter, conventionally the reference frequency f0 was determined without setting the relationship between the value of N/2f0 and M, so when converting the number of pulses N to the distance dK in the distance calculation circuit 8, a complicated process was required. calculation was required, e.g. fO=1
At 00KHz, distance d is d = 0.001715XN from equation (2) as V = 343 m/sI.
[m], which requires complicated calculations and requires a long time.

Purpose of the Invention The present invention has been made to solve the above-mentioned conventional problems, and its purpose is to facilitate calculation in a distance calculation circuit that calculates distance from the output of a counter that counts the number of standard pulses. It is something to do.

Structure of the Invention To achieve this object, the present invention provides a column for counting reference pulses when distance measurement is performed using the number of reference pulses counted within the time given by the transmitted pulse and the received pulse. When / is an M-adic counter, the frequency f0 of the reference pulse is selected as , un (where V: sound velocity, n: an integer) 2fO, which makes it extremely easy to calculate the pulse number-distance conversion in the distance calculation circuit. It is.

Description of examples Examples of the present invention will be described below using specific numerical values.

The configuration is exactly the same as that shown in FIG. The feature of the present invention lies in the way the reference frequency is set in the reference frequency generation circuit 7.

In the first embodiment, if the frequency of the reference frequency generation circuit 7 is set so that the counter 6 is a binary counter, the distance d
is d=2°xN for the reference pulse number N...
・・・・・・・・・・・・・・・・・・・・・・・・(
3) is given by the relational expression. Calculation of equation (3) requires only shifting the output of the binary counter 6 to the left or right by n pits depending on the sign or negative of n, making it extremely easy to calculate the distance d from the reference pulse number N. I can do it.

As a second embodiment, a case where a decimal counter is used as the counter 6 will be described. In this example, u, (v
/2f) = 10", that is, fO = 2X1°・ If the reference frequency f0 is set, the distance d will be d = 1o"xN for the above pulse number N. ...
It is given by the relational expression (4). To calculate equation (4), it is only necessary to shift the output of the 1o-adic counter 6 by n digits to the right or left depending on whether n is positive or negative. can be easily determined.

Generally, when an M-ary counter is used as the counter 6, the reference pulse frequency f0 generated in the reference frequency generation circuit 6
of.

fo = 2・・・・・・・・・
・・・・・・・・・・・・・・・ Since it is given by the relational expression (6), it is only necessary to shift the output digit of the M-ary counter 6 by n digits depending on the sign of n, so it is not complicated. The distance d can be found very easily without any calculations.

DETAILED DESCRIPTION OF THE INVENTION As described above, in the ultrasonic distance measuring device of the present invention, when the counter used to count the reference pulses generated by the reference frequency generation circuit is an M4 counter, the reference pulse frequency f0 is set as fO= 2XM'', the calculation for determining the distance d from the reference pulse number N is extremely simplified, and the calculation time can be significantly shortened.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an ultrasonic distance measuring device which is the basis of the present invention, and FIG. 2 is an output waveform diagram of the main parts of the ultrasonic distance measuring device. 1... Ultrasonic sensor, 2... Transmission circuit, 3... Receiving circuit, 4... Amplitude comparison circuit, 6... Gate Circuit, e...Counter, 7...Reference frequency generation circuit, 8...
・Distance calculation circuit.

Claims (1)

[Claims] An ultrasonic sensor that transmits and receives ultrasonic pulses, a transmitting circuit that generates a transmitting pulse to be applied to the ultrasonic sensor, and a receiver that processes a received signal received by the ultrasonic sensor. a comparison circuit that compares the output of the receiving circuit with a reference voltage and generates an output pulse when the output is equal to or higher than the reference voltage; a reference frequency generating circuit that generates the reference pulse; and a transmission generated in the transmitting circuit. a gate circuit that generates a gate pulse using the pulse and the output pulse of the comparison circuit;
A counter that counts reference pulses for a period determined by the gate pulse of the gate circuit, and a distance calculation circuit that converts the count number of the counter into a distance, and when an M-ary counter is used as the counter, the reference frequency The reference frequency f_O of the generation circuit is v/(2f_O) = M^n (where v: speed of sound, n = integer)
An ultrasonic distance measuring device characterized by being set to satisfy the following relationship.