JPS61260179A - Ultrasonic object detector - Google Patents

Abstract

PURPOSE:To prevent malfunction due to reflected waves from objects other than an object to be detected by providing a transmitter driving means which drives a transmitter to transmit an ultrasonic wave intermittently from the transmitter and a detecting means which detects the object in accordance with the ultrasonic wave reception state of a receiver only when the transmitted ultrasonic wave is received directly by the receiver. CONSTITUTION:A gate is opened intermittently by a transmission gate circuit 6 to send the output of an oscillator 5, and the ultrasonic wave is transmitted intermittently from a transmitter 1. A reception gate circuit 7 detects that the gate of the transmission gate circuit 6 is opened, and the reception gate circuit 7 opens the gate when the ultrasonic wave is received directly by a receiver 2. If an object 3 to be detected does not exist, the ultrasonic wave having a level higher than the detection level is detected, and a detecting circuit 8 discriminates the absence of the object 3 to be detected thereby and does not output the detection signal. If the object 3 to be detected exists between the transmitter 1 and the receiver 2, the level of the received ultrasonic wave is lower than the detection level, and the detecting circuit 8 discriminates the presence of the object 3 to be detected thereby and outputs the detection signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to an ultrasonic object detector that detects objects by arranging a wave transmitter and a wave receiver to face each other.

[Background technology] Conventionally, this type of transmitter and receiver are placed opposite each other, and the level of the ultrasonic waves transmitted by the transmitter and received by the receiver is the same as that of the transmitter and the receiver. Ultrasonic object detectors, so-called transmission-type ultrasonic sensors, detect objects by detecting objects based on the presence or absence of an object between the device and the transmitter. Ta. Therefore, the reflected wave reflected by an object other than the sensing object may be received by the receiver when there is a sensing object between the transmitter and the receiver, Despite this, when there is no object to be detected, the receiver receives a corresponding ultrasonic wave, causing the ultrasonic object detector to malfunction, which is a so-called wrap-around error.

Therefore, in order to prevent malfunctions due to this wraparound,
A method of attaching a horn to the transmitter and receiver to narrow down the directivity of the transmitter and receiver was considered, but the shape became larger and the installation required high precision in direction. Therefore, it had the disadvantage that installation work was difficult.

[Objective of the Invention 1 The present invention has been made in view of the above-mentioned α, and its purpose is to provide ultrasonic object detection that can prevent malfunctions due to reflected waves from objects other than the sensing object. It is about providing the equipment.

[Disclosure of the Invention] (Structure) The present invention has a transmitter and a receiver facing each other, and the level of the ultrasonic waves transmitted by the transmitter and received by the receiver is equal to that of the transmitter. In an ultrasonic object detector that detects objects by detecting objects depending on the presence or absence of an object between the receiver and the receiver, the transmitter is driven intermittently to transmit ultrasonic waves from the transmitter intermittently. The ultrasonic wave transmitted by the transmitter is determined by the distance between the transmitter and the receiver, and the time during which the ultrasonic waves transmitted by the transmitter are directly received by the receiver. It is equipped with a detection means that detects an object based on the ultrasonic reception state, and by intermittently driving the transmitter, the reflected waves reflected from objects other than the sensing object are detected by the sensing object and the transmitter. If the ultrasonic waves are present between the transmitter and the receiver, the ultrasonic waves transmitted by the transmitter will be transmitted to the receiver, which is determined by the distance between the transmitter and the receiver. By detecting objects based on the ultrasonic reception state of the receiver only during the time when the waves are directly received, the reflected waves from objects other than the sensing object do not affect the detection of the object by the detection means, This is to prevent malfunction of the side-sound object detector.

(Embodiment) FIG. 1 is a diagram showing an example of use using an embodiment of the present invention, in which a belt conveyor 4 is installed between a transmitter 1 and a receiver 2 that face each other. A detected object 3 is conveyed and processed by a belt conveyor 4. The transmitter driving means for driving the transmitter 1 is connected to an oscillator 5 and a transmit date circuit 6.
A detection means for detecting the presence or absence of an object from the wave reception state of the wave receiver 2 is constituted by a wave reception date circuit 7 and a detection circuit 8.

The operation of this embodiment with the above-mentioned circuit configuration is as follows.6 The oscillator 5 drives the transmitter 1 and outputs a signal for emitting ultrasonic waves. Conventionally, the output signal of the oscillator 5 was inputted as is to the transmitter 1, but in this embodiment, the output signal is passed through the transmit date circuit 6, and the output signal is input to the transmitter 1 as shown in FIG. 2(a). The date is opened intermittently and the output of the oscillator 5 is sent to the transmitter 1. Therefore, the transmitter 1 is driven only while the date of the transmitter gate circuit 6 is open, and the transmitter 1 transmits ultrasonic waves intermittently. Then, the reception date circuit 7 detects that the transmission date circuit 6 outputs the output of the oscillator 5 to the transmitter 1, that is, the gate of the transmission gate circuit 6 is opened, and When the ultrasonic waves transmitted from the transmitter 1 are directly received by the receiver 2, which is determined by the distance from the transmitter 2, the reception date circuit 7 is opened as shown in the tIS2 diagram ()+). When the date is opened, the date power of this reception date circuit 7 [During the open time, the ultrasonic reception state of the receiver 2 indicates whether the detected object 3 is in the open position between the transmitter 1 and the receiver 2. Detect whether. Figure 2 (c) when there is no sensing object 3.
As shown in the figure, the ultrasonic waves transmitted from the transmitter 1 are transmitted to the receiver 2.
Since the gate Y of the reception gate circuit 7 is open, the output of the receiver 2 is input to the detection circuit 8, and an ultrasonic wave having a level higher than the detection level of the detection circuit 8 is detected. 1) #4IIIi11 Path 8 determines that there is no detection object 3 and does not output a detection signal. Next, when the detection object 3 is between the transmitter 1 and the receiver 2, the level of the ultrasonic wave received by the receiver 2 becomes lower than the detection level of the detection circuit 8, and the detection circuit 8 is activated. It is determined that there is a detection object 3 and a detection signal is output. The detection signal, which is the output of this detection circuit 8, drives an output circuit (not shown), etc. to detect the detected object 3.
This is a display that indicates whether or not a Here, the reflected wave transmitted from the wave transmitter 1 and reflected by an object 9 other than the detection object 3 takes time to reach the wave receiver 2, as shown in FIG. 3(e). Therefore, if the transmitter 1 is driven intermittently, the reflected wave reflected by an object 9 other than the sensing object 3 will be transmitted to the receiver when the sensing object 3 is between the transmitter 1 and the receiver 2. Furthermore, the amount of time that ultrasonic waves transmitted by transmitter 1 are directly received by receiver 2 is determined by the distance between transmitter 1 and receiver 2. By opening the date of the wave receiving date circuit 7 so as to detect an object from the ultrasonic wave receiving state of the ultrasonic wave receiver 2,
By appropriately selecting the open time of the date of the receiving date circuit 7, it is possible to prevent reflected waves from an object 9 other than the sensing object 3 that is extremely close to the sensing object 3 from affecting the sensing state of the sensing object 3. Object 9 other than the sensing object 3 when the sensing object 3 is present between the transmitter 1 and the receiver 2
This prevents the ultrasonic object detector from malfunctioning due to reflected waves.

[Effects of the Invention] As described above, the present invention includes a transmitter driving means that drives the transmitter intermittently to intermittently transmit ultrasonic waves from the transmitter;
It is determined by the distance between the transmitter and the receiver, and the ultrasonic reception state of the receiver is determined by the time when the ultrasonic waves transmitted by the transmitter are directly received by the receiver. Since it is equipped with a detection means that performs detection, the reflected wave transmitted from the transmitter and reflected by an object other than the sensing object is delayed until it reaches the receiver, so that the wave is detected by the transmitter. With intermittent driving, when the sensing object is between the transmitter and the receiver, the reflected waves reflected by objects other than the sensing object will be less likely to be received by the wave receiver, and the waves will be further transmitted. The distance between the transmitter and the receiver determines the object detection based on the receiver's ultrasonic reception state, which is determined by the distance between the transmitter and the receiver. As the detection means detects the object, by appropriately selecting the detection time of the detection means, even reflected waves from objects other than the detection object that are very nearby will not affect the detection state of the detection object. This has the effect of preventing the ultrasonic object detector from malfunctioning due to reflected waves from objects other than the sensing object when the sensing object is present between the transmitter and the receiver.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, and FIGS. 2 and 3 are operation explanatory diagrams of the same. 1 is a transmitter, 2 is a receiver, 3 is a sensing object, 5 is an oscillator,
6 is a transmitting date circuit, 7 is a receiving date circuit, 8 is a detection circuit, and 9 is an object.

Claims (1)

[Claims] (1) A transmitter and a receiver are placed opposite each other, and the level of the ultrasonic waves transmitted by the transmitter and received by the receiver is lower than the object between the transmitter and the receiver. In an ultrasonic object detector that detects an object by changing depending on the presence or absence of the ultrasonic object, a transmitter driving means for intermittently driving the transmitter to intermittently transmit ultrasonic waves from the transmitter; It is determined by the distance between the transmitter and the receiver, and the ultrasonic reception state of the receiver is determined by the time when the ultrasonic waves transmitted by the transmitter are directly received by the receiver. An ultrasonic object detector comprising a detection means for performing detection.