JPS5880575A - Object detecting device - Google Patents

Abstract

PURPOSE:To improve operational accuracy and to simplify utilization with a simple configuration, by deciding that it is noise when a received signal exists in an ultrasonic receiver during a gate opening period after a ultrasonic wave pulse is stopped and preventing an output circuit from operation. CONSTITUTION:An ultrasonic wave sent from an ultrasonic wave pulse transmitter 2 and reflected by an object 1 to be detected is received by an ultrasonic receiver 3 and compared by a comparator 20 and the output from the comparator 20 is held by an FF2 21 for a fixed period. When an ultrasonic wave pulse is outputted, the signal is held by an FF1 11 for a fixed period. A signal outputted from the FF1 11 is inputted to an AND gate 22 to which the output of the FF2 21 is applied and the output from the AND gate 22 is held in an FF3 25 for a fixed period. When a received signal exists in the receiver 3, an output from the FF2 21 is inputted to a stopping circuit 7 and the generation of ultrasonic waves is stopped through an OSC1 6. If a received signal (noise) exists in the receiver during the succeeding opening period of the gate 16, an output circuit 29 is stopped through a gate circuit 23. Consequently the titled device can be easily used with a simple configuration.

Description

Detailed Description of the Invention The present invention transmits ultrasonic pulses to a predetermined space using an ultrasonic pulse transmitter, and receives the reflected waves using an ultrasonic pulse receiver to detect the presence of an object to be detected. The present invention relates to an object detection device that has a simple circuit configuration and high operational accuracy.

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 configured as shown in FIG. 1, in which 1 indicates an object to be detected such as a human body;
2 transmits ultrasonic pulses.

3 is an ultrasonic pulse receiver, 4 is a drive circuit for the ultrasonic transmitter 29, 5 is an AND gate circuit, and 6 is a relatively high-frequency oscillator for generating ultrasonic signals (
(hereinafter referred to as O5C1), 7 is a stop circuit for stopping the emission of the next ultrasonic pulse when the ultrasonic pulse receiver 3 receives a certain signal during the gate opening period after ultrasonic pulse emission. , 8 is a one-shot circuit, and 9 is a relatively low-frequency oscillator (hereinafter o) that determines the period of emission of ultrasonic pulses.
sc2), 10 is a differentiation circuit, 11 is a holding circuit for inputting an ultrasonic pulse signal and holding it for a certain period of time (hereinafter referred to as FF).
1), 12.13 is a not gate circuit, 14 is a differential circuit, 15 is an amplifier circuit (AMP) for amplifying the signal received by the ultrasonic pulse receiver 3, 16 is an AND gate circuit, 17 .18 is the diode, 19 is the detected object 1
A timing circuit provided to set the detection distance range determines the gate opening period after the ultrasonic pulse is emitted.

20 is a comparison port @COM) which compares the signal received by the ultrasonic pulse receiver 3 during the gate opening period with a reference signal (omitted) and outputs it if the reference signal is at a lower level; 21 is a comparison circuit 20 is a holding circuit (hereinafter referred to as FF2) for inputting the output signal and holding it for a certain period of time; 22 and 23 are AND gate circuits; 24 is an ultrasonic pulse receiver 3 during the gate opening period after the ultrasonic pulse has stopped; A no-signal detection circuit 25 outputs a signal when a certain reception signal is not received in the ultrasonic pulse receiver 3, and a no-signal detection circuit 25 outputs a signal when a certain reception signal is not received at the ultrasonic pulse receiver 3. A holding circuit (hereinafter referred to as FF3) that inputs the signal generated when the wave occurs and holds it for a certain period of time.
6 is a clear signal generation circuit for clearing the FF 325, 27 is an AND gate circuit, and 28 is a final signal, that is, when a certain received signal exists during the gate opening period after the ultrasonic pulse is emitted, and when the ultrasonic pulse is stopped. A holding circuit (hereinafter referred to as FF4) that generates a signal generated when a certain received signal does not exist during the subsequent gate opening period and holds it for a certain period of time.
, 29 are output circuits for controlling external loads (omitted) such as switches.

O8C29 is connected to one input of the AND gate circuit 5 via the one-shot circuit 8, O5C, 6 is connected to the other input, and the output of the AND gate circuit 5 is connected to the input of the drive circuit 4. The output of the drive circuit 4 is connected to the ultrasonic pulse 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 22.
is connected to one input of the not gate circuit 1.
3 is connected to human power. The output of the NOT gate circuit 13 is connected to one input of the AND gate circuit 23 and connected to the AND gate circuit 16 via a diode 17.
is connected to one input of the The output of the one-limit 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 111. Also, the one show 1. The output of the gate circuit 8 is connected to the input of the not gate circuit 12, the output of the not gate circuit 12 is connected to the input of the differentiating circuit 14, and the output of the differentiating circuit 14 is connected to the clear input of the FF 221. . The ultrasonic wave receiver 3 is connected to the input of the amplifier circuit 15, the output of the amplifier circuit 15 is connected to the other input of the AND gate circuit 16, and one input of the AND gate circuit 16 is connected to the input of the amplifier circuit 15. At the same time as the diode 17, the output of the timing circuit 19 is connected via the diode 18. The output of the AND gate circuit 16 is connected to the input of the comparison circuit 20, the output of the comparison circuit 20 is connected to the input of the FF 221, and the output of the FF 221 is connected to the other input of the AND gate circuit 22 and stopped. It is connected to circuit 7.

The output of the stop circuit 7 is connected to 05C16.

The output of the no-signal detection circuit 24 is connected to the other input of the AND gate circuit 23, and the output of the AND gate circuit 23 is connected to one input of the AND gate circuit 27. The output of the AND gate circuit 22 is connected to the human power of the FF325, and the output of the FFa25 is connected to the AND gate circuit 2.
The output of the clear signal generating circuit 26 is connected to the clear input of the FFa25.

Further, the output of the AND gate circuit 27 is connected to the input of the FF 428, and the output of the FF 428 is connected to the input of the output circuit 29.

In Fig. 2 (~, (B)), A is the AND gate circuit 5.
In the output waveform, φ is the ultrasonic emission period (when the ultrasonic pulse is stopped +1-, the ultrasonic emission period is 2φ)
, mouth is the output waveform of the amplifier circuit 15, and c is the timing circuit 1.
9 is the output waveform, 2 is the input waveform of one of the AND gate circuits 16, 1 is the gate opening period after ultrasonic pulse emission,
β is the gate opening period after the ultrasonic pulse stops. E is the output waveform of FF111, G is the output waveform of NOT gate circuit 13, G is the output waveform of FF221, H is FF32'5
, the output waveform of the clear signal generation circuit 26,
Nu is the output waveform of the AND gate circuit 23. Figure 2 is when the detected object 1 does not exist, and Figure 2 (5)
is when the detected object is present.

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

First, the ultrasonic pulse shown in FIG. The ultrasonic pulse transmitter 2 transmits (emits) waves into a predetermined space. When the detected object 1 enters the detection distance (sensing distance) range set by the timing circuit 19, the ultrasonic pulse signal reflected by the detected object 1 is received by the ultrasonic pulse receiver 3. The signal is amplified by the amplifier circuit 15 and output as a signal as shown at the beginning of FIG. 2 (8). Then, it is input to one human power of the AND gate circuit 16, and to the other human power of the AND gate circuit 16 (
(after the ultrasonic pulse has been emitted), the signal generated by the timing circuit 19 as shown in C in FIG.
) is applied as shown by α in 2. Therefore, a signal is output to the output of the AND gate circuit 16, and the comparison circuit 2
It is compared and output at ゜. The output is input to the FF 221, and is kept for a certain period of time (at the falling edge of the one shot, to be exact, until the falling edge of the final pulse of the ultrasonic pulse chain shown in FIG. 2A). . A clear signal for the FF 221 is generated by the differentiating circuit 14.

) is retained. Furthermore, when an ultrasonic pulse is emitted, the signal is input to FFIII for a certain period of time (at the rise of the one-shot circuit 8, or more specifically, until the rise of the first pulse of the ultrasonic pulse shoulder shown in Fig. 2A). , in terms of the circuit, a clear signal for the FF 111 is generated by the differential pedal 10). The FF 1ll outputs a signal as shown in FIG. means a signal received after the ultrasonic pulse is emitted, which is applied to the FF 325 and held for a certain period of time.

Then, a received signal is present in the ultrasonic pulse receiver 3, and the FF2
When there is an output of 21, it is manually input to the stop circuit 7, and 05
C16 to stop the emission of the next ultrasonic pulse starting from the broken line part A in FIG. 2(B). Then FF
The output of the AND gate circuit 111 becomes null (low level), which is inverted by the NOT gate circuit 13 and sent to the AND gate circuit 16 via one gate of the AND gate circuit 23 and the diode 17 as a signal as shown in FIG. Applied to one gate. This input signal is as shown in (2) β in Figure 2 (the same signal as in Figure 2), which means that the gate opening signal period α after the ultrasonic pulse stops is longer than the gate opening signal period α after the ultrasonic pulse stops. This means that the signal (period) β is longer. In this way, if there is no received wave fQ4 in the ultrasonic pulse receiver 3 when the gate is opened after the ultrasonic pulse stops +1-, the AND gate circuit 16 will not output, and the output signal of the no-signal detection circuit 24 will be is output, and the AND gate circuit 23
The output signal is output as shown in FIG. 2(B).

Then, the AND gate circuit 27 outputs an output signal, which is applied to the FF 428 and held for a certain period of time.The output signal is applied to the output circuit 29, and the output circuit 29 controls a predetermined controlled object.

Since the object detection device of the present invention has the above configuration,
If there is a received signal (noise) in the ultrasonic pulse receiver 3 during the gate opening period after the ultrasonic pulse stops (as shown in the second β of Fig. 2 fB), the output signal of the AND gate circuit 16 will be output. Since the output signal of the no-signal detection circuit 24 is not output, the output signal of the AND gate circuit 23 is also not output.

Then, the output signal of the γ/gate circuit 27 is not output either, and therefore the output circuit 29 does not operate. Therefore, all received signals during the gate open period after the ultrasonic pulse stops can be judged as noise, and the longer the noise detection period (gate open period after the ultrasonic pulse stops), the more chance there is to detect noise. This allows for highly accurate detection.

Since the object detection device of the present invention has the above-described configuration, it has advantages such as a simple configuration, high operational accuracy, and ease of use.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing an 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 pulse transmitter, and 3 is an ultrasonic pulse transmitter.
indicates an ultrasonic pulse receiver. Agent Patent Attorney Roichi Aihiko Fuku-ichi---------------Toki□□Su□S (A) 11th I

Claims (1)

[Claims] 1. In an object detection device that detects the presence of an object by transmitting an ultrasonic pulse to a predetermined space using an ultrasonic pulse transmitter and receiving the reflected wave by an ultrasonic pulse receiver, stopping means for stopping the transmission of ultrasonic pulses from the ultrasonic pulse transmitter for a certain period when a certain signal is received by the sonic pulse receiver; A transmitting means for transmitting ultrasonic pulses by a sonic pulse transmitter, a certain gate opening period after the transmitting means transmits the ultrasonic pulses, and a period for receiving reflected waves of the ultrasonic pulses; means for providing a constant gate opening period even after the ultrasonic pulses are stopped by the stopping means, and the gate opening period after the ultrasonic pulses are stopped by the stopping means to be longer than the gate opening period after the ultrasonic pulses are transmitted; An object detection device comprising: means for detecting an object.