JPS6359113B2 - - Google Patents

Description

Detailed Description of the Invention The present invention is an object that detects the presence of an object by transmitting ultrasonic pulses to a predetermined space using an ultrasonic transmitter and receiving the reflected waves using an ultrasonic receiver. The present invention relates to a detection device, and particularly to an object detection device that has reliable operation accuracy with few malfunctions.

An embodiment of the object detection device of the present invention will be described below with reference to the drawings.

The object detection device of the present invention is constructed as shown in FIG. A sound wave receiver, 4 a drive circuit for the ultrasonic transmitter 2, 5 an AND gate circuit, 6 a relatively high-frequency oscillator for generating ultrasonic signals (hereinafter referred to as OSC ₁ ), 7 an ultrasonic pulse emission A stop circuit for stopping the emission of the next ultrasonic pulse when the ultrasonic receiver 3 receives a signal during the gate opening period after (transmission, wave transmission), 8 is a one-shot circuit, 9 is an ultrasonic wave a relatively low-frequency oscillator (hereinafter referred to as OSC ₂ ) that determines the period of pulse emission; 10 is a differentiating circuit;
11 is a holding circuit (hereinafter referred to as FF ₁ ) for inputting an ultrasonic pulse signal and holding it for a certain period of time; 12 is FF ₁ 1
Not gate circuit for inverting the output of 1, 13
1 is an amplifier circuit for amplifying the signal received by the ultrasonic receiver 3, 14 is an AND gate circuit, and 15 is a timing circuit provided to set the detection distance range of the object to be detected 1, which controls the gate opening period. It has been decided. 16 is a comparison circuit that compares the signal received by the ultrasonic receiver 3 during the gate opening period with a reference signal (omitted), and outputs an output if the reference signal is at a lower level; 17 and 18 are AND gates; A circuit 19 is a no-signal detection circuit that outputs a signal depending on whether or not a certain received signal is present in the ultrasonic receiver 3 during the gate opening period after the ultrasonic pulse stops, and 20 is an AND circuit. The gate circuit 21 inputs a signal generated when an ultrasonic pulse signal exists (is emitted) and a certain reception signal is received by the ultrasonic receiver 3 during the subsequent gate opening period, and 22 is a clear signal generation circuit for clearing FF _{2 21} , 23 is an AND gate circuit, 24 is a final signal, that is, an ultrasonic pulse signal (existence); The following signals are generated at the same time: the received signal ○ present (present) during the subsequent gate opening period, the ultrasonic pulse stop ○ present (stopped), and the received signal ○ absent (absent) during the subsequent gate opening period. A holding circuit (hereinafter referred to as FF ₃ ) receives the signal and holds it for a certain period of time, and 25 is an output circuit for controlling an external load (omitted) such as a switch.

The OSC ₂ 9 is connected to one input of the AND gate circuit 5 via the one-shot circuit 8, and the OSC ₁ 6 is connected to the other input. The output of the AND gate circuit 5 is connected to the input of the drive circuit 4, 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. ing. The output of the stop circuit 7 is connected to the OSC ₁ 6, the output of the one shot circuit 8 is connected to the input of the differentiating circuit 10,
The output of the differentiating circuit 10 is connected to the clear signal input of FF ₁ 11 to be input as a clear signal of FF ₁ 11.

The output of the AND gate circuit 5 is connected to the input of FF ₁ 11, and the output of FF ₁ 11 is connected to the input of the NOT gate circuit 12 and one input of the AND gate circuit 17. The output of the not gate circuit 12 is connected to one input of an AND gate circuit 18. Further, the ultrasonic receiver 3 is connected to the input of an amplifier circuit 13, and the output of the amplifier circuit 13 is connected to one input of an AND gate circuit 14. The output of the AND gate circuit 14 is connected to the input of a comparison circuit 16, and the output of the comparison circuit 16 is connected to the other input of the AND gate circuit 17.

The output of the timing circuit 15 is also connected to the other input of the AND gate circuit 18, and the AND gate circuit 18 is connected to one input of the AND gate circuit 20, and the other input is connected to the no signal detection circuit 1.
9 is connected, and the output of the AND gate circuit 20 is connected to one input of the AND gate circuit 23. The output of the AND gate circuit 17 is
It is connected to the input of FF ₂ 21, and the output of FF ₂ 21 is connected to the other input of AND gate circuit 23.

The output of the clear signal generation circuit 22 is connected to the clear signal input of the FF ₂ 21, the output of the AND gate circuit 23 is connected to the input of the FF ₃ 24,
The output of the FF ₃ 24 is connected to the input of an output circuit 25.

In FIGS. 2A and B, A is the output waveform of the OSC ₁ 6, B is the output waveform of the one-shot circuit 8, C is the output waveform of the AND gate circuit 5, and D is the amplifier circuit 13.
2B is the output waveform of the timing circuit 15, and in FIG. 2B, a is the gate opening period after the ultrasound pulse is emitted, and b is the gate opening period after the ultrasound pulse is stopped. F is the output waveform of FF ₁ 11,
Top is the output waveform of the not gate circuit 12, h is the output waveform of the clear signal generation circuit 22, li is the output waveform of the FF ₂ 21, nu is the output waveform of the AND gate circuit 20, and ru is the output waveform of the AND gate circuit 23. . FIG. 2A shows a state in which the detected object 1 is not present, and FIG. 2B shows a state in which the detected object 1 exists.

Next, the operating state of the object detection device configured as described above will be explained.

First, OSC ₁ 6, OSC ₂ 9 and one shot circuit 8
The ultrasonic pulse signal shown in C of FIG. 2A generated by the above is applied to the ultrasonic transmitter 2 via the drive circuit 4, and is transmitted (emitted) to a predetermined space. Then, when the detected object 1 enters the detection distance (sensing distance) range set by the timing circuit 15, the ultrasonic signal inverted by the detected object 1 is received by the ultrasonic receiver 3, and the amplification circuit 13 The signal is amplified and output as a signal as shown in FIG. 2B (d). A signal is input to one input of the AND gate circuit 14, and a signal as shown in a of FIG. The fact that the object 1 is within the detection distance range means that when the timing circuit 15 outputs the second signal from the amplifier circuit 13
This means that a signal as shown in d of FIG. B is output, and therefore the output signal of the AND gate circuit 14 is output. The output signal is sent to the comparator circuit 16.
The comparison circuit 16 outputs an output signal when it is compared with a reference signal and if the level is higher than the reference signal. The output signal is input to one input of the AND gate circuit 17, and when an ultrasonic pulse signal is generated, that signal, that is, the output signal of the AND gate circuit 5 is input to the FF ₁ 11, and the FF ₁ 11
holds the output as shown in FIG. 2B until it is cleared by a signal differentiated by the differentiating circuit 10 of the next output signal of the one-shot circuit 8. Applicable
The output signal of FF ₁ 11 is input to the other input of AND gate circuit 17 . Since the output signal (omitted) of the comparison circuit 16 is also output while the output signal of the FF ₁ 11 is being output, the output signal of the AND gate circuit 17 is also output and input to the FF ₂ 21, and the output of the FF ₂ 21 is The signal is held until cleared by the clear signal generation circuit 22. In this case, the fact that a signal as shown in Figure 2B C is output means that a certain received signal was present during the gate opening period after the ultrasonic pulse was emitted. This means that there is a received signal during the gate opening period.

At this time, the stop circuit 7 is activated, and as shown in FIG.
The emission of ultrasonic pulses is stopped as shown in the intermittent portions of (c). If no ultrasonic pulse is generated, the output signal of the AND gate circuit 5 is null, and since there is no input signal to FF ₁ 11, the output signal is also null. Then, an output signal is outputted to the output of the not gate circuit 12, and the output signal of the timing circuit 15 is outputted to one input of the AND gate circuit 18, and the output signal of the timing circuit 15 is outputted to the other input of the AND gate circuit 18. The output signal is output during the gate opening period after the ultrasonic pulse stops. That is, the second
It means b in E of Figure B. b of Figure 2B
If a certain received signal does not exist during the period shown in , the output signal of the no-signal detection circuit 19 is outputted and applied to one input of the AND gate circuit 20, and the output of the AND gate circuit 18 is applied to the other input. Therefore, the AND gate circuit 20 outputs a signal as shown in FIG. 2B. (The fact that this signal is output means that there was no certain reception signal during the gate opening period after the ultrasonic pulse stopped, and the reception signal during the gate opening period after the ultrasonic pulse was This means that there is no signal.

Therefore, by inputting the signal shown in FIG. 2B and the output signal of the FF ₂ 21 shown in FIG. signal is output. The second
The signals shown in Figure B mean that the ultrasonic pulse ○ is present, the subsequent received signal ○ is present during the gate opening, and the ultrasonic pulse ○ is not present, and the subsequent received wave signal ○ is not present during the gate opening. , the signal is input to the FF ₃ 24, held for a certain period of time, and applied to the output circuit 25, which controls a predetermined controlled object.

In the object detecting device of the present invention, the object detecting means determines that a detected object exists only when the signal detecting means and the no-signal detecting means output. Even if either one of the detection means outputs an output, the object detection means does not malfunction, and an extremely highly accurate object detection device can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing one embodiment of the object detection device of the present invention, and FIG. 2 is a waveform diagram of each part of FIG. 1. In the drawing, 1 is an object to be detected, 2 is an ultrasonic transmitter,
3 is an ultrasonic receiver, and 11, 21, and 24 are holding circuits.

Claims (1)

[Claims] 1. An object detection device that transmits ultrasonic pulses to a predetermined space using an ultrasonic transmitter and receives the reflected waves using an ultrasonic receiver to detect the presence of an object to be detected. A transmitting means for transmitting ultrasonic pulses at a constant cycle by the ultrasonic transmitter, and a reference signal for detecting the signal received by the ultrasonic receiver and the presence of a detected object. a comparison circuit that compares the received signal and outputs an output when the received signal is equal to or higher than the level of the reference signal; a holding circuit that holds a drive signal for driving the ultrasonic transmitter of the wave transmitting means; a signal detection means for detecting that the comparison circuit is output during the output of the holding circuit; and a stop for stopping the transmission of ultrasonic pulses from the ultrasonic transmitter for a certain period of time based on the output of the comparison circuit. means, no-signal detecting means for detecting that there is no received signal in the ultrasonic receiver while the operating signal of the stopping means is output, and output signals of the signal detecting means and the no-signal detecting means are inputted. 1. An object detection device comprising: an object detection means that determines that a detected object exists only when the detected object is present.