JPS6378084A - Ultrasonic distance measuring equipment - Google Patents

Abstract

PURPOSE:To obtain the circuit constitution which does not cause an erroneous decision, even if an ultrasonic transmitted wave directly trespassed electrically or acoustically and received, by constituting a masking means in the final receiving stage. CONSTITUTION:An ultrasonic transmitting means 8 consisting of an ultrasonic transmitter 4, a reference signal generator 5 and a transmitting circuit 6 transmits intermittently an ultrasonic signal to an object. An ultrasonic receiving means 12 consisting of an ultrasonic receiver 9 and an amplifying circuit 11 receives a reflected wave corresponding to the ultrasonic signal. Subsequently, an output stage of the circuit 11 is connected to a switching circuit 13 being a masking means which has been synchronized with a pulse signal from the generator 5, and at the time of transmission, an operation of the circuit 11 is stopped. On the other hand, an amplified received signal level S5 is inputted to a comparing circuit 14 being a delay time detecting means, compared with a comparison voltage S4 corresponding to a distance, and a digital signal S6 having a delay time width corresponding to the distance is outputted. This signal S6 is compared with pulse signals of plural stages which have been set in advance, which a control means 15 has and decided, and the distance is controlled by the control means 15.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an ultrasonic distance meter used to detect the distance to an object using ultrasonic waves.

2. Description of the Related Art Conventionally, this type of ultrasonic distance meter has had a configuration as shown in FIG. In FIG. 3, 1 is an ultrasonic transmitting means;
This is the part that pulse-modulates and transmits ultrasonic waves. The ultrasonic receiving means 2 receives the ultrasonic signal, and the delay time detects the time difference from the time of transmission by the ultrasonic transmitting means 1 until the ultrasonic receiving means 2 receives the reflected wave from the reflecting object. It consisted of a detection means 3.

Problems to be Solved by the Invention In such a conventional configuration, the transmitted waves electrically go around directly to the receiving circuit, and the transmitted ultrasonic waves directly enter the receiver due to ultrasonic interference around the horn opening. , there was a problem that the waves could be mistakenly judged as reflected waves from a reflecting object.

The present invention is intended to solve these problems, and aims to provide a circuit configuration that does not cause erroneous judgments even when ultrasonic transmission waves are directly received electrically or acoustically.

Means for Solving the Problem In order to solve this problem, the present invention provides an ultrasonic transmitting means that intermittently transmits an ultrasonic signal toward an object, and a reflected wave corresponding to the ultrasonic signal. Set a comparison voltage corresponding to the distance between the ultrasonic wave receiving means and the time difference from the time when the ultrasonic signal is transmitted from the ultrasonic wave transmitting means until it is reflected by the object and received by the ultrasonic wave receiving means. a delay time detection means for outputting a pulse width corresponding to the delay time using a comparing means, and a delay time detection means provided at the final stage of reception to prevent the ultrasonic wave from becoming a directly received wave during transmission and being received by the ultrasonic reception means. It is composed of a masking means and a control means for outputting a digital signal of multiple stages corresponding to the distance.

Effect: With this configuration, even if a signal directly enters the receiving stage during ultrasonic transmission, the masking circuit turns off the receiving means for a certain period of time, and no malfunction occurs. Furthermore, even if the transmitted ultrasonic waves acoustically go around the receiver, by setting the comparison voltage high using the distance-compatible comparison voltage, it is possible to provide a highly stable ultrasonic distance meter that does not cause false judgments due to the go around. .

Embodiment □ FIG. 1 is a block diagram showing the configuration of an ultrasonic distance meter according to an embodiment of the present invention, and FIG. 2 is a time chart showing signal waveforms of each part thereof. In FIGS. 1 and 2, reference numeral 4 denotes an ultrasonic transmitter, which generates a pulse signal S2 and an ultrasonic signal S1 from a reference signal generator 5, and transmits a pulse-modulated ultrasonic transmission signal S3 from a transmitting circuit 6 to the ultrasonic transmitter 4. An ultrasonic transmitting means 8 is configured to apply the ultrasonic wave to the ultrasonic transmitter 4 and radiate the ultrasonic wave from the ultrasonic transmitter 4 into the air via the horn section 7. Reference numeral 9 denotes an ultrasonic receiver, which receives ultrasonic waves reflected from a target object (reflecting object) and enters through a horn section 10, and converts the ultrasonic waves into electrical signals. The received ultrasonic signal is then amplified via an ultrasonic receiving means 12 consisting of an ultrasonic receiver 9 and an amplifier circuit 11. The output stage of this amplifier circuit 11 is connected to a switching circuit 13 synchronized with the pulse signal from the reference signal generator 5, and this switching circuit 13 provides masking means for stopping the operation of the amplifier circuit 11 during transmission. It consists of on the other hand,
The amplified received signal level s6 is input to the comparison circuit 14, where it is compared with a comparison voltage S4 corresponding to the distance, and outputs a digital signal S6 having a delay time width corresponding to the distance. This comparison.

The digital signal S6 of the delay time detecting means formed by the circuit 14 is compared with a plurality of preset pulse signals of the control means 16, and the distance is controlled by the control means 15.

Effects of the Invention As described above, according to the present invention, even if there is electrical interference of the transmission signal generated in the circuit configuration, the interference signal can be cut by configuring the masking means at the final receiving stage. It can prevent misjudgment money. In addition, even if the ultrasonic waves emitted into the air cause sound interference due to obstacles around the ultrasonic transmitter and receiver, and unnecessary signals are directly received, they can be cut by the above-mentioned masking means and distance correspondence comparisons can be made. By comparing with the voltage, it is possible to prevent judgment errors. By using the signal from the reference signal generator as a reference, setting the masking time, setting the comparison voltage, and determining the distance, it is possible to perform highly accurate distance measurement without malfunction.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an ultrasonic distance meter according to an embodiment of the present invention, FIG. 2 is a time chart showing each signal waveform in the block diagram, and FIG. 3 is a conventional ultrasonic distance meter. It is a block diagram. 4... Ultrasonic transmitter, 6... Reference signal generator, 6... Transmission circuit, 7... Horn section, 8...・Ultrasonic transmitting means, 9...
Ultrasonic receiver, 1o... Horn part, 11...
...Amplification circuit, 12...Ultrasonic receiving means, 1
3... Switching circuit, 14... Old comparison circuit, 15... Control means. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure I5 Figure 2 Figure 3

Claims (1)

[Claims] an ultrasonic transmitter that intermittently transmits an ultrasonic signal toward a target object; an ultrasonic receiver that receives a reflected wave corresponding to the ultrasonic signal; and an ultrasonic signal that is transmitted from the ultrasonic transmitter. delay time detecting means for outputting a pulse width corresponding to the delay time by means of a comparison means having a comparison voltage set corresponding to the distance, based on the time difference between the time when the ultrasonic wave is reflected from the object and the ultrasonic wave is received by the ultrasonic reception means; Masking means provided at the final stage of reception so as to prohibit the ultrasonic waves from becoming direct reception waves and being received by the ultrasonic reception means during transmission;
An ultrasonic distance meter consisting of a control means that outputs a digital signal corresponding to the distance.