JPH09329658A - Detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the size of a sensor by reducing the scale of a signal processing circuit by switching the input of a plurality of detected signals outputted from a light receiving lens to a signal processing means at such timing that the input is asynchronously time-divided with switches. SOLUTION: Light rays made incident on PDs (light receiving elements) 1 and 2 are transduced into electric currents and detected signals I1 and I2 are intermittently sent to a light receiving circuit 8 through switches SW1 and SW2. The switches SW1 and SW2 are alternately switched to each other at the clocks of oscillating pulse signal SG1 and SG2 supplied from an oscillation circuit 7 and the signals I1 and I2 passing through the switches SW1 and SW2 are sent to the circuit 8 at such timing that the signals are asynchronously time-divided. Since the detected signals are processed by signal processing means of one system in paired states, the same number of light receiving circuits 8, amplifier circuit 9, S/H circuits 10, A/D conversion circuit 11, etc., as that of light receiving outputs is not required and the scale of a signal processing circuit can be reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detector for detecting an object to be detected by a passive method, and more particularly to a technique for processing a detection signal by time resolution.

[0002]

2. Description of the Related Art As a conventional detector, a so-called distance setting type photoelectric sensor will be described with reference to the block diagram of FIG. 25 and the time chart of the detecting operation of FIG.
The detector 101 drives the light projecting circuit 103 with the pulse signal obtained by the oscillation circuit 107, and projects the light from the light projecting element 104 through the light projecting lens 105.

The light emitted from the light projecting element 104 is reflected by the detection object 2, enters the two light receiving elements 3a and 3b through the light receiving lens 3, and the respective light receiving elements 3 are received.
Light-current conversion is performed by a and 3b according to the amount of light. These currents are converted into voltages by the light receiving circuits 8a and 8b and amplified by the amplifier circuits 9a and 9b. These amplified detection signals are respectively stored in a sample hold circuit (hereinafter referred to as S /
It is sampled and held by H circuits 10a and 10b, and converted into digital signals by analog-digital conversion circuits (hereinafter referred to as A / D conversion circuits) 11a and 11b. These digital signals are differentially calculated by the differential calculation circuit 12 and then compared with a preset threshold value by the comparison circuit 16. The threshold value is set at a level according to the set distance, and when a differential signal exceeding the threshold value is input, an ON signal indicating that the detected object 2 is closer than the set distance, When the differential signal below the threshold value is input, the comparison circuit 16 outputs an OFF signal indicating that the detected object 2 is farther than the set distance. The output signal of the comparison circuit 16 has an integration circuit 17 for removing noise.
After passing through, the output circuit 18 turns it ON / O outside the sensor.
It is output as an FF signal. The integrator circuit 17 outputs an ON signal when the number of ON signals output from the comparison circuit 16 is continuously 3 or more, and an OFF signal when the number of OFF signals output from the comparison circuit 16 is continuously 3 or more. It is supposed to be output.

[0004]

However, in the conventional detector 101 as described above, the light receiving circuits 8a and 8b, the amplifier circuits 9a and 9b, and the S / H corresponding to the number of received light outputs are provided.
Since the circuits 10a and 10b and the A / D conversion circuits 11a and 11b are required, the scale of the signal processing circuit becomes large,
There are problems that it is difficult to reduce the size of the sensor, reduce the cost, and reduce the current consumption. Further, in this configuration, since it is necessary to match the characteristics between the light receiving circuits 8a and 8b and the signal processing circuit, there is a problem that a highly accurate circuit is required. Further, since the detector 101 detects the object 2 by the reflected light of the light projected by itself, the detection performance greatly depends on the projected light amount. Since the amount of light projected is determined by the amount of current passed through the light projecting element 104, it is difficult to reduce the current consumption, and when the detector 101 is driven by a battery, it is difficult to drive it for a long time.

The present invention has been made in order to solve the above-mentioned problems. By reducing the scale of the signal processing circuit, it is possible to reduce the size of the sensor, reduce the cost, and reduce the current consumption. It is another object of the present invention to provide a passive type detector that does not require a highly accurate circuit.

[0006]

In order to achieve the above object, the present invention provides a passive detector for detecting an object to be detected by receiving light from the object to be detected. Light receiving means for receiving light from the object to be detected or the background object existing in the light receiving field by a plurality of light receiving elements and outputting detection signals of a plurality of systems based on the received light amount, and a plurality of systems. Gate means for time-resolving each detection signal, pulse generating means for supplying a pulse signal to the gate means so that each detection signal passes through the gate means asynchronously and in time division, and time-resolving by the gate means A signal processing means for detecting a light quantity variation between the light receiving fields by processing the detected signals paired and performing signal processing in one system.

In the above arrangement, the plurality of detection signals output from the light receiving means are switched to the signal processing means by the gate means asynchronously at timings such that they are time-divided. Since it is possible to process the detection signal of 1 by the signal processing means of one system, it is not necessary to provide the same number of signal processing circuits as the number of light receiving outputs and the number of light receiving circuits as in the conventional photoelectric sensor. The scale of the signal processing circuit can be reduced, and circuit components can be reduced, current consumption can be reduced, the outer shape of the detector can be reduced, cost can be reduced, and a defective manufacturing rate can be reduced. Further, by simplifying the circuit configuration, it is not necessary to match the characteristics of a plurality of circuits, so that high precision parts are not required. Furthermore, since this detector uses a passive method that does not require a light projecting current, it is possible to further reduce current consumption,
When the battery is driven, the battery life can be extended.

The present invention further comprises control means for controlling the supply of power to the signal processing means, the control means synchronizing the pulse of the pulse generating means and processing the paired detection signal. The means may supply power only for the time required for processing.

In this configuration, power is supplied to the signal processing means intermittently, and the signal processing means is supplied with power only for the time required for simultaneous processing of the paired detection signals. Can be further reduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram of a detector according to the present embodiment, and FIG. 2 is a time chart showing the operation of this detector. The detector 1 is a passive type in which the presence or absence of the detection object 2 is detected by receiving the background of natural scattered light (for example, a lighting device, sunlight) at the place where the detector is placed and the reflected light from the detection object 2. The light receiving portion (light receiving means) is the light receiving lens 3 and the light receiving lens 3
Composed of a two-division photodiode (light receiving element, hereinafter abbreviated as PD1 and PD2) arranged behind the
The first and second light receiving visual fields are formed. FIG.
Shows the state in which the detection object 2 has entered one of the two light-receiving fields (field of view 2).

Normally, the reflected light from the background (for example, one white surface) is incident on PD1 and PD2 through the lens 3. The light incident on PD1 and PD2 is photo-current converted here, and the detected current I1 from PD1 and the detected current I2 from PD2 are switched (gate means) SW1 and SW.
At 2, the light is intermittently sent to the light receiving circuit 8. This switch SW
1, 1 and SW2 are alternately switched by the clocks of the oscillation pulse signals SG1 and SG2 supplied from the oscillation circuit (pulse generation means) 7, and as a result,
The timings of the currents I1 and I2 passing through the switches SW1 and SW2 are asynchronous and time division. Detection current I1, I2
Is converted into a voltage by the light receiving circuit 8 and then amplified by the amplifier circuit 9 to become detection voltages V1 and V2. This voltage V1, V2
Are sampled by the S / H circuit 10 at the timing of the sample and hold signal SH of the oscillation circuit 7, and then converted into digital signals by the A / D conversion circuit 11 and output D respectively.
1 and D2. These outputs D1 and D2 are subjected to difference calculation (D1-D2) in the calculation section 12 to obtain a calculation result D. The threshold value (V
T1, VT2) is set in the threshold setting circuit 14.

When the detected object (black surface) 2 enters the field of view 2, the amount of light incident on the PD 2 decreases and D2 decreases. The calculation result D by the calculation unit at this time becomes larger than the previous D. This is compared with the above threshold values (VT1, VT2) in the comparison circuit 16, and as shown in FIG.
Is higher than VT1 or lower than VT2, the comparison circuit 1
An ON signal is output from 6. This ON signal passes through the integrating circuit 17 to remove noise, and then the output circuit 18
Is output as an ON / OFF signal from the outside of the sensor 1. The integrator circuit 17 outputs an ON signal when the number of ON signals output from the comparison circuit 16 continuously becomes three or more, and an OFF signal when the number of OFF signals output from the comparison circuit 16 continuously becomes three or more. Is output.

As described above, the two systems of detection signals (I1, I
2) are alternately switched and each detection signal is paired and processed by one system of signal processing means, so that the same number of light receiving circuits 8 and amplifier circuits 9 as the light receiving outputs are obtained as in the conventional sensor. , The S / H circuit 10, the A / D conversion circuit 11, etc. are unnecessary, the scale of the signal processing circuit can be reduced, and the number of circuit components, the consumption current, the outer shape, and the cost can be reduced. It is possible to reduce the manufacturing defect rate. Also, by simplifying the circuit configuration,
Since it is not necessary to match the characteristics of a plurality of circuits, highly accurate parts are not required. Further, in this configuration, since the detection is performed by the passive method that does not require the light projecting current, it is possible to reduce the current consumption. Also,
By reducing the current consumption, it is possible to extend the life of the battery when the battery is driven.

(Second Embodiment) FIG. 3 is a block diagram of a detector according to the present embodiment. This detector 20 has switches SW1 and SW2 provided between PD1 and PD2 and the light receiving circuit 8 in the detector 1 shown in FIG.
It is provided between the amplifier circuit 9 and the S / H circuit 10. The detection currents I1 and I2 from the PD1 and PD2 are converted into voltages by the respective light receiving circuits 8a and 8b, amplified by the amplifier circuits 9a and 9b, and then the switches SW1 and SW.
At 2, the signals are alternately switched according to the clocks of the signals SG1 and SG2, and the voltages become V1 and V2. in this way,
Since the switching is performed after the detection signals are amplified in the amplifier circuits 9a and 9b, it is not necessary to put a switching element in a line with a high impedance (a minute signal line), so that switching noise superimposed on the light reception signal is reduced. be able to.

(Third Embodiment) FIG. 4 is a block diagram showing the vicinity of the switch SW of the detector according to the present embodiment. In this embodiment, the switch SW is a field effect transistor (hereinafter referred to as FE).
(T). As a result, switching can be performed at high speed, and since leakage current is almost eliminated, it is possible to detect minute changes in the detected current and more accurately detect the presence / absence of an object. Further, since the FET is controlled by the voltage, the consumption current can be further suppressed.

(Fourth Embodiment) FIG. 5 is a block diagram of the vicinity of the switch SW of the detector according to the present embodiment. In this embodiment, the switch SW is composed of a bipolar transistor. Since the bipolar transistor has a small spike noise due to switching, it is possible to detect a minute change in the detected current, and it is possible to more accurately detect the presence or absence of an object.

(Fifth Embodiment) FIG. 6 is a block diagram of a detector according to this embodiment, and FIG. 7 is a time chart of the operation of this detector. This detector 21 is the same as the detector 1 shown in FIG. 1 except that the switch SW2 is switched to the signal SG2.
And the output signal of the second comparison circuit 22 is ANDed for switching. The light received by PD1 and PD2 is converted into detection currents I1 and I2.
1 and I2 pass through the light receiving circuit 8, the amplification circuit 9, the S / H circuit 10 and the A / D conversion circuit 11 and become outputs D1 and D2 as in the first embodiment. Here, the output D1 is the second
If the value of the output D1 is different before and after the sampling data, the comparison circuit 22 outputs an ON signal. This output signal and A of signal SG2
The switch SW2 is switched by the ND. On the other hand, the output D2 is the data holding circuit 23 and the second comparison circuit 2
The previous data is continuously output until the release signal by the ON signal of 2 is input, and when the release signal by the ON signal of the second comparison circuit 22 is input, the data held in the data holding circuit 23 is updated. To be done. This output D2 and output D1
Is subjected to a differential operation in the operation section 12, and an operation result D is obtained. The calculation result D is compared by the comparison circuit 16 with preset threshold values VT1 and VT2. The comparison circuit 16 is
An ON signal is output when the calculation result D exceeds VT1 or falls below VT2. When the number of ON signals becomes three or more in succession, a binarized ON signal is obtained from the integrating circuit 17, and this signal is output from the output circuit 18, and the sensor 2
1 Notify the outside of the detection object 2 entering the light-receiving visual field.

In this way, the signal (I1) of the one side path (SW1) is monitored, and if there is a change in the signal, the other path (SW2) is operated. It is possible to further reduce current consumption as compared with. Further, since the two systems of detection signals (I1, I2) obtained by the passive system are processed by the signal processing circuit including one system of the light receiving circuit, the scale of the signal processing circuit can be reduced, and the above-mentioned first It is possible to obtain the same operational effect as that of the above embodiment.

(Sixth Embodiment) FIG. 8 is a block diagram of a detector according to this embodiment, and FIG. 9 is a time chart of the operation of this detector. This detector 26 is obtained by adding a modulation circuit 28 to the detector 1 shown in FIG. This modulation circuit 28 has sg1, supplied from the oscillation circuit 27.
Pulse-time modulate each sine wave of sg2, sh, a / d,
The signal is converted into pulse signals of SG1, SG2, SH, and A / D.

The light incident on PD1 and PD2 is photo-current converted here, and the detected current I1 from PD1 and PD are detected.
The detection current I2 from 2 is intermittently sent to the light receiving circuit 8 by the switches SW1 and SW2. This switch SW1, S
W2 is an oscillation pulse signal SG supplied from the oscillation circuit 7.
1 and SG2 are alternately switched, so that the timings of the currents I1 and I2 passing through the switches SW1 and SW2 are asynchronous and time division. The detection currents I1 and I2 are converted into voltages by the light receiving circuit 8 and then amplified by the amplifier circuit 9 to detect voltages V1 and V2.
Becomes The voltages V1 and V2 are sampled by the S / H circuit 10 at the timing of the sample and hold signal SH of the oscillation circuit 7, and then converted into digital signals by the A / D conversion circuit 11 to become outputs D1 and D2, respectively. These outputs D1 and D2 are subjected to difference calculation (D1-D2) in the calculation unit 12,
The calculation result D is obtained. This value D is compared with the threshold value VT in the comparison circuit 16, and when it exceeds VT, an ON signal is output. If the number of ON signals becomes three or more in succession, a binarized ON signal is obtained from the integrating circuit 17, and this signal is output from the output circuit 18 to notify the outside of the sensor 26 that the detected object 2 has entered. .

In this way, the two systems of detection signals (I1, I2) obtained by the passive method are alternately switched,
Data is held by sample-holding each detection signal as a pair and processed by a signal processing circuit including one light receiving circuit, so that the scale of the signal processing circuit can be reduced. It is possible to obtain the same effect as that of the embodiment. In addition, the clock signal that switches the detection signal is pulse-time modulated, synchronized with the signal, and processed to remove physical noise and electrical noise that differ from the periodic detection target. Therefore, a high S / N detection signal can be obtained. This makes it possible to handle a smaller change in the detected current, which enables more accurate detection of the presence or absence of an object.

(Seventh Embodiment) FIG. 10 is a block diagram of a detector according to the present embodiment, and FIG. 11 is a time chart of this detector. This detector 30 is obtained by adding a switch SW3 (control means) for controlling the timing of power supply to the signal processing circuit to the detector 1 shown in FIG. 1 described above. The switch SW3 is switched by a signal AG synchronized with the signals SG1 and SG2 supplied from the oscillation circuit 7. As a result, the power is supplied by the signal S as shown in the time chart of FIG.
It is performed only for the time required for signal processing related to each of G1 and the signal SG2.

In this way, the two systems of detection signals (I1, I2) obtained by the passive method are alternately switched,
Data is held by sample-holding each detection signal as a pair and processed by a signal processing circuit including one light receiving circuit, so that the scale of the signal processing circuit can be reduced. It is possible to obtain the same effect as that of the embodiment. In addition, since the power supply to each signal processing circuit is intermittently performed for the time required for signal processing, the current consumption can be further reduced. Further, since the power is supplied according to the respective oscillation pulse signals of the signal SG1 and the signal SG2, the voltage V1 and the voltage V1 are supplied.
Even if the pulse intervals of the signal SG1 and the signal SG2 are wide so that the two signals do not interfere with each other, it is possible to deal with the excessive input detection signal while maintaining the effect of reducing the current consumption.

(Eighth Embodiment) FIG. 12 shows a time chart of the operation of the detector according to the present embodiment. The detector according to the present embodiment is the detector 30 according to the seventh embodiment described above.
It has the same structure as. The switch SW3 uses signals SG1 and SG2 supplied from the oscillation circuit as a pair of signals, and is switched by a signal AG synchronized with the pair of signals. As a result, as shown in the time chart of FIG. 12, the power is supplied to the signals SG1 and SG2 at the same time for the time required for signal processing related to them.

In this way, the two systems of detection signals (I1, I2) obtained by the passive method are alternately switched,
Data is held by sample-holding each detection signal as a pair and processed by a signal processing circuit including one light receiving circuit, so that the scale of the signal processing circuit can be reduced. It is possible to obtain the same effect as that of the embodiment. In addition, since power is supplied to each signal processing circuit only for the time required for signal processing of the signal SG1 and the signal SG2, if the pulse cycle of the signal SG1 and the signal SG2 is lengthened, the power supply time becomes longer. Since the length is shortened, it is possible to further reduce the current consumption.

(Ninth Embodiment) FIG. 13 is a block diagram of a detector according to this embodiment, and FIG. 14 is a time chart of this detector. This detector 31 is the detector 30 shown in FIG. 10 described above, and performs switching of the switch SW3 by the signals SG1 and SG2 supplied from the oscillation circuit 7. As described above, by supplying the power to each circuit and switching the detection signal by the same signal, the oscillation pulse signal can be reduced and the configuration of the oscillation circuit 7 can be simplified, so that the circuit scale can be reduced and the current consumption can be reduced. Can be further reduced.

(Tenth Embodiment) FIG. 15 is a block diagram of a detector according to the present embodiment, and FIG. 16 is a time chart of this detector. This detector 32 is the same as the detector 1 shown in FIG. 1 except that a switch SW4 is added between PD1 and PD2 and the light receiving circuit 8, and further, an amplifier circuit 9 and an S / S circuit.
A band pass filter 19 is added to the H circuit 10. The switch SW4 is switched by the signal FG synchronized with the signals SG1 and SG2.

Each PD outputs a detection current corresponding to the light input power to the PD, a current I1 is output from PD1, and a current I2 is output from PD2. The detection currents I1 and I2 are sent to the light receiving circuit 8 through the switches SW1 and SW2, and further through the switch SW4. The pulse width of the signal FG for controlling the switch SW4 is set to the signals SG1,
Since the pulse width is smaller than SG2, the detection currents I1 and I2 can be chopped and converted into high-frequency signals. The detection currents I1 and I2 are received by the light receiving circuit 8
Is converted into a voltage by the amplifier circuit 9 and amplified by the amplifier circuit 9 to obtain the voltage V
1, V2. By passing these voltages V1 and V2 through the bandpass filter 19, low-frequency noise of the power source generated when a fluorescent lamp is used as the light source and the light receiving elements PD1 and P1.
Noise such as high frequency noise generated in D2 and the light receiving circuit 8 can be removed. Noise-removed signal F1,
F2 is sampled by the S / H circuit 10 at the timing of the sample hold signal SH of the oscillation circuit 7, and then A / D
It is converted into a digital signal by the conversion circuit 11 and becomes outputs D1 and D2, respectively. These outputs D1 and D2 are the calculation unit 12
The difference calculation (D1-D2) is carried out to obtain a calculation result D. This value D is compared with the threshold value VT in the comparison circuit 16, and VT
When it exceeds, the ON signal is output. When the number of ON signals is three or more in succession, a binarized ON signal is obtained from the integrating circuit 17, and this signal is output from the output circuit 18 to notify the outside of the sensor 32 that the detected object 2 has entered. .

As described above, according to the detector 32 of the present embodiment, the two systems of detection signals (I
1, I2) are alternately switched and each detection signal is sampled and held as a pair to hold the data and to be processed by the signal processing circuit including one light receiving circuit, thus reducing the scale of the signal processing circuit. Therefore, it is possible to obtain the same effects as those of the above-described first embodiment. In addition, by chopping the detection signal, converting it into a high frequency signal, and further removing noise with the filter 19,
Since optical noise and electrical noise can be removed, a high S / N detection signal can be obtained. As a result, it is possible to handle a smaller change in the detection signal, which enables more accurate detection of the presence or absence of the object.

(Eleventh Embodiment) FIG. 17 is a block diagram of a detector according to this embodiment, and FIG. 18 is a time chart of this detector. The detector 33 according to this embodiment is configured to convert a detection signal into a high frequency signal when the switches SW1 and SW2 are switched. That is, the current I1 from the PD1 and the current I from the PD2
2 has signals SG1 and SG by switches SW1 and SW2.
Alternately switched with two clocks. These detection currents I1 and I2 include power supply low frequency noise generated when a fluorescent lamp is used as a light source. In order to remove them, conversion into a high-frequency signal that is separated from low-frequency noise is also performed when the switches SW1 and SW2 are switched, and then passed through a bandpass filter 19.

As described above, the two systems of detection signals (I1, I2) obtained by the passive method are alternately switched,
Data is held by sample-holding each detection signal as a pair and processed by a signal processing circuit including one light receiving circuit, so that the scale of the signal processing circuit can be reduced. It is possible to obtain the same effect as that of the embodiment. In addition, by performing time regulation and waveform shaping at the same time, the dedicated switching gate for waveform shaping and the oscillating pulse signal given to it can be deleted. Therefore, the circuit scale is reduced as compared with the detector 32 described above. be able to.

(Twelfth Embodiment) FIG. 19 is a block diagram of a detector according to the present embodiment. This detector 34
In the detector 33 shown in FIG. 17 described above, the oscillation circuit 7
Is configured to output oscillation pulse signals of multiple frequencies,
By changing the passing frequency of the filter 19 according to the change of the oscillation frequency, it is possible to cope with the change of the noise situation caused by the change of the use environment.

The light incident on PD1 and PD2 is photo-current converted here, and the detection current I1 from PD1 and PD are detected.
The detection current I2 from 2 is intermittently sent to the light receiving circuit 8 by the switches SW1 and SW2. This switch SW1, S
W2 is an oscillation pulse signal SG supplied from the oscillation circuit 7.
1 and SG2 are alternately switched, so that the timings of the currents I1 and I2 passing through the switches SW1 and SW2 are asynchronous and time division. The currents I1 and I2 are converted into voltages by the light receiving circuit 8 and then amplified by the amplifier circuit 9 to become voltages V1 and V2.
The voltages V1 and V2 are passed through the band pass filter 19 to remove low frequency noise and become voltages F1 and F2. The voltages F1 and F2 are sampled by the S / H circuit 10 at the timing of the sample hold signal SH. The sampled detection signals are converted into digital signals by the A / D conversion circuit 11 and then become outputs D1 and D2, respectively. These outputs D1 and D2 are subjected to difference calculation (D1-D
2) is performed and the operation result D is obtained. This calculation result D is compared with the threshold value VT by the comparison circuit 16, and when it exceeds VT, O
An N signal is output. When the number of ON signals becomes three or more in succession, a binarized ON signal is obtained from the integrating circuit 17, and the output circuit 18 notifies the outside of the sensor 34 that the detected object 2 has entered.

When the usage environment in which the detector 34 is placed changes, the frequency of noise such as low frequency noise of power source included in the detection signal output from the PD also changes. Therefore, in order to accurately detect the presence / absence of an object, the oscillation pulse signals SG1 and S1 output from the oscillation circuit 7 in accordance with changes in the usage environment.
It is necessary to change the oscillation frequency of G2 and further change the pass frequency of the filter 19 so as to extract only the detection signal in conjunction with it. Detector 34 according to the present embodiment
Signal SG in order to avoid the frequency of noise in the operating environment.
Switch SW5 for externally changing the frequency of SG1 and SG2
The low cutoff frequency 1 / (2πRsC of the filter 19 depends on the position of the switch SW5.
s) is the oscillation frequency of the oscillation pulse signals SG1, SG2 1 /
It can be changed in conjunction with (2πRoCo).

In this way, the two systems of detection signals (I1, I2) obtained by the passive method are alternately switched,
Data is held by sample-holding each detection signal as a pair and processed by the signal processing circuit including one light receiving circuit, so that the scale of the signal processing circuit can be reduced. The same action and effect as the form can be obtained. Further, by changing the oscillation frequencies of the oscillation pulse signals SG1 and SG2 of the received light signal according to the noise condition of the use environment, and in conjunction with this, changing the pass frequency of the filter 19 that extracts only that signal, the periodic Since it is possible to remove physical quantity noise and electrical noise different from those to be detected, a high S / N detection signal can be obtained and a smaller signal can be handled.

(Thirteenth Embodiment) FIG. 20 is a block diagram of a detector according to this embodiment. The detector 35 according to the present embodiment is configured so that the gain of the amplifier circuit 9 can be changed in association with the change in the oscillation frequency of the oscillation pulses SG1 and SG2.

The light incident on PD1 and PD2 is photo-current converted here, and the detected current I1 from PD1 and PD are detected.
The detection current I2 from 2 is intermittently sent to the light receiving circuit 8 by the switches SW1 and SW2. This switch SW1, S
W2 is an oscillation pulse signal SG supplied from the oscillation circuit 7.
1 and SG2 are alternately switched, so that the timings of the currents I1 and I2 passing through the switches SW1 and SW2 are asynchronous and time division. The currents I1 and I2 are converted into voltages by the light receiving circuit 8 and then amplified by the amplifier circuit 9 to become voltages V1 and V2.
The voltages V1 and V2 are passed through the band pass filter 19 to remove low frequency noise and become voltages F1 and F2. The voltages F1 and F2 are sampled by the S / H circuit 10 at the timing of the sample hold signal SH. The sampled detection signals are converted into digital signals by the A / D conversion circuit 11 and then become outputs D1 and D2, respectively. These outputs D1 and D2 are subjected to difference calculation (D1-D
2) is performed and the operation result D is obtained. This calculation result D is compared with the threshold value VT by the comparison circuit 16, and when it exceeds VT, O
An N signal is output. When the number of ON signals is three or more in succession, a binarized ON signal is obtained from the integrating circuit 17, and the output circuit 18 notifies the outside of the sensor 35 that the detected object 2 has entered.

When the operating environment in which the detector 35 is placed changes, the frequency of noise such as low frequency noise of power source included in the detection signals output from PD1 and PD2 also changes. Therefore, in order to accurately detect the presence / absence of an object, the oscillation frequencies of the oscillation pulse signals SG1 and SG2 output from the oscillation circuit 7 are changed in accordance with the change in the usage environment, and only the detection signal is interlocked with it. It is necessary to change the gain of the amplifier circuit 9 so as to take it out. The detector 35 according to the present embodiment uses a switch S that externally changes the frequencies of the signals SG1 and SG2 in order to avoid the frequency of noise in the usage environment.
W5 is added, and the gain Rf / Rs of the amplifier circuit 9 can be changed in association with the oscillation frequency 1 / (2πRoCo) of the oscillation pulse signals SG1 and SG2 by the position of the switch SW5.

In this way, the two systems of detection signals (I1, I2) obtained by the passive method are alternately switched,
Data is held by sample-holding each detection signal as a pair and processed by the signal processing circuit including one light receiving circuit, so that the scale of the signal processing circuit can be reduced. The same action and effect as the form can be obtained. Furthermore, by changing the oscillation frequencies of the oscillation pulse signals SG1 and SG2 of the light receiving signal according to the noise condition of the use environment and changing the gain of the amplifier circuit 9 in conjunction with it, a physical quantity different from the periodic detection target is obtained. Since noise and electrical noise can be removed more accurately, a high S / N detection signal can be obtained and a smaller signal can be handled.

(Fourteenth Embodiment) FIG. 21 is a diagram showing the structure of an infrared sensor according to the present embodiment. The infrared sensor 40 according to the present embodiment is the detector shown in the above-described first to thirteenth embodiments, which includes an infrared detection element 42 (thermopile or the like) instead of the PD. As a result, the circuit scale of the infrared sensor 42 for detecting the intrusion of a person 43 into the detection area can be reduced and simplified, so that the outer shape of the sensor 40 can be reduced and the cost can be reduced. it can.

(Fifteenth Embodiment) FIG. 22 is a diagram showing the structure of a temperature sensor according to the present embodiment. The temperature sensor 44 according to the present embodiment includes the temperature detection element 45 in place of the PD in the detector shown in the above-mentioned first to thirteenth embodiments. As a result, it is possible to reduce and simplify the circuit scale of the temperature sensor 44 used for temperature control and the like in equipment such as a molding machine.

(Sixteenth Embodiment) FIGS. 23A and 23B.
FIG. 3 is a diagram showing a configuration of a pressure sensor according to the present embodiment and an equivalent circuit thereof. Pressure sensor 46 according to the present embodiment
In the detector shown in the first to thirteenth embodiments, the pressure detecting element 47 is provided in place of the PD. As a result, the circuit scale of the pressure sensor 46 that controls the pressure unit of the molding machine or the like can be reduced and simplified.

(Seventeenth Embodiment) FIG. 24 is a diagram showing the structure of a gas sensor according to the present embodiment. The gas sensor 48 according to the present embodiment is the detector shown in the above-described first to thirteenth embodiments, and includes a gas detection element 49 instead of the PD. As a result, the circuit scale of the gas sensor 48 for detecting mixed gas control and gas leakage can be reduced and simplified.

[0044]

As described above, according to the present invention, in the passive type detector for detecting the detection object by receiving the light from the detection object, the gate means is provided between the light receiving element and the signal processing circuit. The pulse generation means controls the detection signal output from the light receiving element to pass through the gate means asynchronously in a time division manner, and the detection signals are paired and processed by a signal processing circuit of one system. As a result, since the detection signals of a plurality of systems output from the light receiving element can be processed by the signal processing circuit of one system, the scale of the signal processing circuit can be reduced as compared with the conventional detector, Reduction of circuit parts, reduction of current consumption,
It is possible to reduce the outer shape of the detector, reduce the cost, reduce the manufacturing defect rate, and the like.

Further, according to the present invention, the power is supplied to the signal processing circuit only for the time required for the signal processing of the paired detection signals, so that the power consumption can be further reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a detector according to a first embodiment of the present invention.

FIG. 2 is a time chart of the detection operation of the detector according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram of a detector according to a second embodiment of the present invention.

FIG. 4 is a configuration diagram near a switch of a detector according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram in the vicinity of a switch of a detector according to a fourth embodiment of the present invention.

FIG. 6 is a configuration diagram of a detector according to a fifth embodiment of the present invention.

FIG. 7 is a time chart of the detection operation of the detector according to the fifth embodiment of the present invention.

FIG. 8 is a configuration diagram of a detector according to a sixth embodiment of the present invention.

FIG. 9 is a time chart of the detection operation of the detector according to the sixth embodiment of the present invention.

FIG. 10 is a configuration diagram of a detector according to a seventh embodiment of the present invention.

FIG. 11 is a time chart of the detection operation of the detector according to the seventh embodiment of the present invention.

FIG. 12 is a time chart of the detection operation of the detector according to the eighth embodiment of the present invention.

FIG. 13 is a configuration diagram of a detector according to a ninth embodiment of the present invention.

FIG. 14 is a time chart of the detection operation of the detector according to the ninth embodiment of the present invention.

FIG. 15 is a configuration diagram of a detector according to a tenth embodiment of the present invention.

FIG. 16 is a time chart of the detection operation of the detector according to the tenth embodiment of the present invention.

FIG. 17 is a configuration diagram of a detector according to an eleventh embodiment of the present invention.

FIG. 18 is a time chart of the detection operation of the detector according to the eleventh embodiment of the present invention.

FIG. 19 is a configuration diagram of a detector according to a twelfth embodiment of the present invention.

FIG. 20 is a configuration diagram of a detector according to a thirteenth embodiment of the present invention.

FIG. 21 is a configuration diagram of an infrared sensor according to a fourteenth embodiment of the present invention.

FIG. 22 is a configuration diagram of a temperature sensor according to a fifteenth embodiment of the present invention.

23A is a plan view and a sectional view of a pressure sensor according to a sixteenth embodiment of the present invention, and FIG. 23B is a circuit configuration diagram of the sensor.

FIG. 24 is a configuration diagram of a gas sensor according to a seventeenth embodiment of the present invention.

FIG. 25 is a block diagram of a conventional detector.

FIG. 26 is a time chart of the detection operation of the conventional detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Detector 2 Detecting object (object to be detected) 3 Light receiving lens (light receiving means) 7 Oscillation circuit (pulse generating means) 8 Light receiving circuit (signal processing circuit) 9 Amplifying circuit (signal processing circuit) 10 S / H circuit (signal processing Circuit) 11 A / D conversion circuit (signal processing circuit) SW1 switch (gate means) SW2 switch (gate means) SW3 switch (control means) PD1 photodiode (light receiving element; light receiving means) PD2 photodiode (light receiving element; light receiving means) )

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinya Otsuki 10 Ouron Co., Ltd., Hanazono Dodocho, Ukyo-ku, Kyoto City, Kyoto Prefecture

Claims (2)

[Claims] 1. A passive-type detector for detecting an object to be detected by receiving light from the object to be detected, wherein a plurality of light-receiving fields of view are formed, and the object to be detected or a background object existing in the field of light-receiving is detected. Light is received by a plurality of light receiving elements, and light receiving means for outputting detection signals of a plurality of systems based on the amount of received light, gate means for time-resolving each detection signal of the plurality of systems, and each detection signal The pulse generating means for supplying a pulse signal to the gate means so that the timing of passing through the gate means is asynchronous and time division, and each detection signal time-resolved by the gate means is paired to form a signal in one system. A signal processing means for detecting a light amount variation between the light-receiving fields by processing the detector. 2. A control means for controlling the supply of power to the signal processing means, wherein the control means synchronizes with the pulse of the pulse generating means and outputs the paired detection signal as the signal. The detector according to claim 1, wherein the processing means supplies power only for a time required for processing.