JPS5870186A - Object detector - Google Patents

Abstract

PURPOSE:To lessen malfunction remarkably with respect to an object detecting device where ultrasonic pulses are transmitted from an ultrasonic wave transmitter to a prescribed space and reflected waves are received by an ultrasonic wave receiver to detect the existence of an object to be detected. CONSTITUTION:When an object 1 to be detected is put in a detection distance range set by a timing circuit 17, the ultrasonic signal reflected by the object 1 to be detected is received by an ultrasonic wave receiver 3 and is inputted to one input of an AND gate circuit 16 through an amplifying circuit 15. A signal is inputted to the other input of the circuit 16 from the timing circuit 17, and the output signal of the circuit 16 is outputted and is compared with a reference signal in a comparing circuit 18; and if this output signal has level higher than that of the reference signal, a signal is outputted and is inputted to an FF2 19 and is held for a certain time and is inputted to one input of an AND gate circuit 20 and is applied to a stopping circuit 7 as a driving signal. The operation of the circuit 7 is continued until the FF2 19 is cleared by a signal at the next predeterminate time of transmission of ultrasonic pulses, namely, a signal at the fall of the output waveform of a one shot circuit 8.

Description

[Detailed description of the invention] The present invention transmits ultrasonic pulses to a predetermined space using an ultrasonic transmitter, and receives the reflected waves by an ultrasonic receiver to detect the presence of an object to be detected. The present invention relates to an object detection device, and particularly to an object detection device with extremely low malfunctions and high operational accuracy.

Conventional object detection devices of this type have the disadvantage that noise causes malfunctions and low operational accuracy, making it impossible to reliably detect the object to be detected. The present invention eliminates the above-mentioned drawbacks and relates to a 7゛ζ object detection device. Hereinafter, one embodiment of the object detection device of the present invention will be described with reference to the drawings.

The object detection device of the present invention is constructed as shown in FIG. 1, in which 1 indicates an object to be detected such as a human body;
2 is an ultrasonic transmitter for transmitting ultrasonic pulse signals, 3 is an ultrasonic receiver, 4 is a drive circuit for the ultrasonic transmitter 2, 5 is an AND gate circuit, and 6 is an ultrasonic signal generator. A relatively high frequency oscillator (hereinafter referred to as O8C□), 7 is an ultrasonic receiver 3 during the gate opening period after ultrasonic pulse emission (wave transmission, transmission)
a stop circuit for stopping the emission of the next ultrasonic pulse when a certain signal is received; 8 is a one-shot circuit; 9
10 is a relatively low frequency oscillator (hereinafter referred to as OSC) that determines the period of emission of ultrasonic pulses; 10 is a differential circuit; 11 is a differential circuit;
12 is a holding circuit (hereinafter referred to as FF1) for inputting an ultrasonic pulse signal and holding it for a certain period of time; 12 is a not gate circuit;
13 is a differential circuit, 14 is a not gate circuit, and 15 is an amplifier circuit (A) for amplifying the signal received by the ultrasonic receiver 3.
MP), 16 is an AND gate circuit, 17 is detected object 1
The gate opening period is determined by a timing circuit provided to set the detection distance range. 18 is a comparison circuit (COM) which compares the signal received by the ultrasonic receiver 3 during the gate opening period 9 with a reference signal (omitted) and outputs it if the reference signal is at a lower level; 19 is a comparison circuit 18 is a holding circuit (hereinafter referred to as FF) for inputting the output signal and holding it for a certain period of time, 20° 21 is an AND gate circuit, and 22 is an ultrasonic receiver 3 during the gate opening period after the ultrasonic pulse is stopped. 23 is an AND gate circuit, and 24 is a no-signal detection circuit that outputs a signal when a certain received signal is not received. A holding circuit (hereinafter referred to as FF3) which inputs the signal generated when the wave is received by the transducer 3 and holds it for a certain period of time; 25 is a clear signal generation circuit which generates a clear signal to clear the FF 324; 26 is an AND The gate circuit 27 is used when a constant received signal exists during the gate opening period after the final signal, that is, the ultrasonic pulse signal is emitted, and when a constant received signal does not exist during the gate opening period after the ultrasonic pulse stops. A holding circuit (to which the signal to be generated is input and held for a certain period of time)
(hereinafter referred to as FF), 28 is an output circuit for controlling an external load (omitted) such as a switch.

08C29 is connected to one input of the AND gate circuit 5 via the one-shot circuit 8, and the other input is 0.
8C16 is connected, the output of the AND gate circuit 5 is connected to the input of the drive circuit 4, and the output of the drive circuit 4 is connected to the ultrasonic transmitter 2.

The output of the AND gate circuit 5 is further connected to the input of the FF 111, and the output of the FF 111 is connected to the AND gate circuit 2.
Connected to one input of 0. The output of the FF circuit 11 is connected to the input of a NOT gate circuit 14, and the output of the NOT gate circuit 14 is connected to one input of an AND gate circuit 21.

The output of the one-shot circuit 8 is connected to the input of a differentiating circuit 10, and the output of the differentiating circuit 10 is connected to the clear input of the FF□11. Further, the output of the one-shot circuit 8 is connected to the input of a NOT gate circuit 120, and the output of the NOT gate circuit 12 is connected to the input of the differentiating circuit 13. The output of the differentiating circuit 13 is connected to the clear input of the FF 219. The ultrasonic receiver 3 is connected to the input of an amplifier circuit 15, the output of the amplifier circuit 15 is connected to one input of an AND gate circuit 16, and the output of a timing circuit 17 is connected to the other input. .

The output of the AND gate circuit 16 is connected to the input of the comparison circuit 18, the output of the comparison circuit 18 is connected to the input of the FF 219, and the output of the FF 19 is connected to the other input of the AND gate circuit 20 and the stop circuit. 7 is connected. The output of the timing circuit 17 is connected to the other input of the AND gate circuit 21. The AND gate circuit 21
The output of the AND gate circuit 23 is connected to one input of the AND gate circuit 23, the output of the no-signal detection circuit 22 is connected to the other input, and the output of the AND gate circuit 23 is connected to one input of the AND gate circuit 26. has been done. The output of the AND gate circuit 20 is connected to the input of the FF324, and the output of the AND gate circuit 20 is connected to the input of the FF324.
The output of F324 is connected to the other input of the AND gate circuit 26. The output of the clear signal generation circuit 25 is connected to the clear input of the FF 324. The output of the AND gate circuit 26 is connected to the input of the FF 27, and the output of the FF 27 is connected to the input of the output circuit 28.

In FIG. 2 (5), Φ), (5) is when the detected object 1 is not present, and a3) is when the detected object 1 is present. In Fig. 2 (4) and (B), A is the output waveform of 08C16, C is the output waveform of the one-shot circuit 8, C is the output waveform of the AND gate circuit 5, =
is an amplifier circuit, 5° output H type, and O is Io.

In Figure 2 CB), a is the gate opening period after the ultrasonic pulse is emitted, b is the gate opening period after the ultrasonic pulse is stopped, and 0 is the output waveform of the FF 111. G is the output waveform of the not gate circuit 14, H is the FF
, 19 are the output waveforms, ri is the output waveform of the clear signal generation circuit 25, nu is the FF, 24 is the output waveform, and ru is the output waveform of the AND gate circuit 23.Next, object detection configured as above Describe the operating status of the device.

First, 08C16, □SC, 9 and one-shot circuit 8
Accordingly, an ultrasonic pulse signal as shown in C of FIG. 2(4) is applied to the ultrasonic transmitter 2 via the drive circuit '4311, and is transmitted (emitted) to a predetermined space.

When the detected object 1 enters the detection distance range (sensing distance range) set by the timing circuit 17, the ultrasonic signal reflected by the detected object 1 is received by the ultrasonic receiver 3 and amplified. A signal as shown in FIG. 2 (CB)-2 after being amplified by the circuit 15 is input to one input of the AND gate circuit 16.The other input of the AND gate circuit 16 is connected to a timing circuit 17. Therefore, the signal as shown in a of E in FIG. ), it means that the signal shown in 2 is output, and therefore the AND gate circuit 1
The output signal of No. 6 is output, and the output signal is compared with a reference signal (omitted) in a comparison circuit 18, and if the level is higher than the reference signal, the comparison circuit 18 outputs the output signal. The output signal is then input to the FF 219 and held for a certain period of time, and the output signal of the FF 219 is input to one input of the AND gate circuit 20 and is applied to the stop circuit 7 as a drive signal for the stop circuit 7. The stop circuit 7 operates until the FF 219 is cleared by a signal when the next ultrasonic pulse is scheduled to be emitted (although it is not actually emitted), that is, a signal at the falling edge of the output waveform of the one-shot circuit 8. sustained. This can be seen in the one-shot circuit 8 in FIG.
The output of the not gate circuit 12 is applied to the not gate circuit 12, and its output is input to the differentiating circuit 13, where it becomes an instantaneous signal at the falling edge of the one-shot circuit 8. It is input to the clear inputs of 9FF and 19, and the output is input to the differential circuit 13. , 19 operations are cleared. Further, when emitting ultrasonic pulses, the ultrasonic pulse, that is, the output of the AND gate circuit 5, is input to the FF 11, and the FF 111
holds the output as shown in ) and 2 of FIG. 2 until it is cleared by the next differentiated signal of the output signal of the one-shot circuit 8 by the differentiating circuit 10. The output is input to the other input of the AND gate circuit 20, and the FF
□Since the output signal of FF 19 is also output while the output signal of 11 is being outputted (as shown in Fig. 2 [F]) and H), the output signal of the AND gate circuit 20 is also output, and the output signal of FF 24 is output.
is input. The output signal of the FF 324 is held until cleared by the clear signal generation circuit 25. (Second
This signal power is shown in Figure (6). The fact that it has been output means that a certain received signal was received by the ultrasonic receiver 3 during the gate opening period after the ultrasonic wave was emitted. means. ) Then, the emission of the next ultrasonic pulse is stopped by the operation of the stop circuit 7 due to the presence of a certain reception signal during the gate opening period after the above-mentioned ultrasonic pulse is emitted. Then, FF 11 has no input signal and no output signal. Therefore, the inverted output, that is, the output signal 0 is outputted to the output of the NOT gate circuit 14, and the output, that is, the output as shown in FIG. , and the other input is connected to the output of the timing circuit 17.
A signal as shown in is applied, and the AND gate circuit 2
The output signal 1 corresponds to the gate opening period after the ultrasonic pulse has stopped, and this signal is input to one input of the AND gate circuit 23. If the sound wave receiver 3 does not receive a certain received signal, the output signal of the no-signal detection circuit 22 is outputted and inputted to the other input of the AND gate circuit 23.

Then, the fact that this signal is output as shown in the output signal of the AND gate circuit 23 (FIG. 2) means that there was no certain received signal during the gate opening period after the ultrasonic pulse stopped. ) is input to the other input of the AND gate circuit 26.

Then, as described above (by the operation of the FF 24, if a certain received signal is present during the gate opening after emitting the RS sound pulse), the output signal of the FF 24 is input to one of the inputs of the AND gate circuit 26. Since the output signal of the AND gate circuit 26 is input to A signal indicating that the
A multi-output circuit operates based on the output of F and 27. Also, the FF
The output of 427 is held for a certain period of time.

(Clear signal omitted).

As mentioned above, the received signal is input to the holding circuit, and the output of the holding circuit drives the stop circuit for stopping the emission of ultrasonic pulses, so it is possible to stop the ultrasonic pulses reliably. Therefore, it is possible to obtain an object detection device with high operating accuracy.

Since the object detection device of the present invention has the above configuration,
1- It has the advantage of very little movement and high movement precision.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing the configuration of an embodiment of the object detection device of the present invention, and FIG. 2 shows waveforms of various parts of FIG. 1. In the drawings, 1 is an object to be detected, 2 is an ultrasonic transmitter, 3 is an ultrasonic receiver, and 11, 19, 24, and 27 are holding circuits. Agent Patent Attorney Aihiko Fukushi

Claims (1)

[Claims] L An object detection device that detects the presence of an object by transmitting an ultrasonic pulse to a predetermined space using an ultrasonic transmitter and receiving the reflected wave by an ultrasonic receiver. means for stopping the transmission of ultrasonic pulses from the ultrasonic transmitter for a certain period of time when a certain signal is received by the ultrasonic receiver; A transmitting means for transmitting ultrasonic pulses by a sonic wave transmitter, and a constant reception signal from the ultrasonic receiver is inputted into a holding circuit, and the output signal of the holding circuit is used as an ultrasonic pulse stop signal. What is claimed is: 1. An object detection device comprising means for detecting an object to be detected by repeating the operations of the stopping means and the wave transmitting means.