JPS61102576A - Reflection type photoelectric switch - Google Patents

Abstract

PURPOSE:To obtain the constitution of a reference voltage generating circuit suitable to IC-implementation by connecting the output terminal of a current mirror circuit to the reference input terminal of a comparing circuit and connecting a transistor (TR) for reference voltage switching to part of an output-side load resistance is parallel. CONSTITUTION:A circuit which compares the difference signal between both outputs of position detection type photodetectors 4a and 4b with a reference voltage for distance setting is provided, and the reference voltage generation part constituted by connecting the output terminal of the current mirror circuit M1 where a variable resistor VR1 for reference voltage setting is connected to the input side through a resistance-current converting circuit CT1 to the reference input terminal of the comparing circuit and also connecting the TR Q4 for reference voltage switching to part of the output-side load resistance in parallel is provided. Then, the reference voltage is switched automatically simultaneously with the detection of a body to lower a return photodetection level and thus provide detection sensitivity hysteresis, and the input current of the current mirror circuit M1 is adjusted by a variable resistor Rd for detection distance setting to prevent the setting or variation of the hysteresis width from exerting influence upon the detection reference voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field 1 The present invention relates to a reflective photovoltaic device that has been used in Birch/Gumemeters and the like.

1 Dorsal Cardinal Surgery 1 This type of reflective photoelectric switch is constructed by installing light emitting and receiving optical systems 1 and 2 laterally at a predetermined distance from D, as shown in FIG. 1(a).
The beam P emitted from the light projecting element 3 is reflected by the detected object X by δL, and the reflected light R is received by the optical system 2.
As shown in Fig. 2(b), when the light is focused on the detected object X, the detected object X is It detects whether or not it exists in the detection area, and its circuit configuration, as shown in FIG. 2, includes two receiving elements 4a placed side by side within the light collection plane.

The output current of 4b is outputted by the light receiving circuits Sa and Sb,
Convert to No. voltage, and further convert Guinami/Cre// to 16, and use it to fire! After being logarithmically converted by the L conversion circuits 6a and 6b, it is input to the differential amplifier circuit 7, and the difference output is sent to the comparison circuit 8.
As the signal human power V10, it is compared with the reference voltage for detection distance setting which is output from one unit that generates a standard voltage. However, when using the sensor outdoors, there are differences in the reflectance of the frame and the object to be detected, etc.

Conventionally, this base wall voltage generating section 9, as shown in FIG.
Since it was composed of a constant voltage source ~ref and a variable resistor VR, it had the following drawbacks. 6 (1) When converting the circuit into an IC, the constant voltage source Vref is usually set to a substitute value. However, with this conventional circuit configuration, it is not possible to obtain a distance setting voltage d greater than \'ref.

(2) Two external δ6 connection terminals a for connecting the variable resistor VR.
+b is required, which is disadvantageous for IC implementation.

(3) In order to prevent repeated operation and recovery due to 'iL/chair at the time of detection, it is necessary to have a so-called hysteresis characteristic that switches to the reference voltage for recovery at the same time as detection, but this conventional circuit has a hysteresis characteristic. It is extremely difficult to construct a circuit to make the width variable.

[Objective of the Invention 1 The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a reflective charging switch with the above-mentioned hysteresis characteristic in detection sensitivity, especially when integrated into an IC. The object of the present invention is to provide a configuration of a reference voltage generation circuit suitable for the.

1 Disclosure of the Invention 1 The present invention compares the level of reflected light from a detected object with a detection reference voltage using a comparison circuit, and when a detector determines that the detected object is within a set distance, automatically sets a return standard. In the reflection type charging switch configured to switch the wall voltage, the output end of the current mirror circuit, which has a resistor-ring conversion circuit on the input side and connects a variable resistor for setting the detection reference voltage, is connected to the output end of the current mirror circuit as described above. In addition to connecting to the reference input terminal of the comparison circuit,
It is configured by connecting a reference voltage switching transformer in parallel to part of the load resistance on the output side, and by adjusting the input current of the current mirror circuit with a variable resistor for setting the detection distance, the output current By making it a constant current, the resistance value that sets the hysteresis width does not affect the detection reference voltage.

Since FIG. 3 shows an embodiment of the present research, the current mirror circuit N11 is formed on a single chip with a common base part.
The bases of transistors Q, , Q, on the input side and output side are connected to the collector of the transistor Q1 on the input side, and a resistor-current conversion circuit CT is connected to the collector of the transistor Q on the input side.

Variable resistor VR for setting the detection reference voltage.

is connected. The resistance-current conversion circuit CT is composed of a differential amplifier DA, a transistor Q controlled by its output, and a constant voltage source Vre stage, and a transistor is connected to the inverting input till of the differential amplifier 2'iDA. , the emitters of which are each connected to a constant voltage source VrJ on the non-inverting input side. When the current 1d is changed by changing the resistance value of the variable resistor VR, the voltage fluctuation at point d is fed back to the input side of the differential amplifier DA, and the voltage at point d is always Vrer.
Since it is controlled to be equal to the variable resistor VR,
A current 1d that is inversely proportional to the resistance value can be obtained with high accuracy. In addition, the collector of the output terminal C of the current mirror circuit 11 and the output side transistor Q has a resistor Rd for setting the detection base voltage Vd as a load resistor,
A resistor Rh is connected in series for 3 hours to determine the hysteresis width, and the voltage at the output terminal C is the standard voltage\+
d, the full! of the comparator circuit 8 shown in FIG. 1 (applied to the input terminal.Furthermore, the hysteresis width setting resistor R1+ is connected in parallel with a basic voltage switching transistor/) Q, which is turned on at the same time as the object is detected.

In the above configuration, the current mirror circuit key 11 has a common base I formed on a single chip, and both transistors Q
1 and Q are matched with each other, and the output current is defined by the diode-connected input side transistor Q, and the total input current is determined by the output side transistor Q2. The same lefter current 1ild as that of the input side transistor Q1 always flows, and there is no influence on the value of the load resistance Jt. Therefore, by the object detection signal),! ; K'i voltage voltage switching transistor ON/OFF control 11, the voltage across the sensing substrate voltage setting resistor Rd does not change, and the hysteresis width setting resistor R
By making 1+ variable, the detection reference voltage and hysteresis width can be adjusted independently without affecting each other.

In reality, the comparator circuit is input to the comparator/2. is extremely high, so the output terminal C of the current mirror circuit is likely to pick up noise, and it is extremely difficult to make part of the load resistance to be IIj'&-2. An example of improving this point is shown in Figure 2. In the same figure, a variable resistor VR2 for setting the hysteresis width is connected to the input side via a resistance-voltage L conversion circuit CT. The output current 11+ of the mirror circuit M+ is supplied via the diode D to the resistor Rh for setting the terinos width described in iii, and this output '4e
The above-mentioned hysteresis/ground width switching tiger/nostar Q4 is connected to the opening between the ground and the ground.

If configured as shown in 1st and 1, a constant current 11+ is supplied to the hysteresis width setting resistor R1+ from the second constant current source composed of the mirror circuit M2, and this current value is determined by the current mirror circuit. Variable resistor\1<: on the input side of
Since I can be adjusted, there is no risk of noise being introduced to the input terminal of the comparator circuit (and the detection reference voltage and hysteresis width can be set independently of each other).

1. Effects of the Invention As described above, in the present invention, the level of reflected light from an object is compared with the detection reference voltage, and when an object is detected, the reference voltage rT:, 1) Switching method charging is performed. In the switch, the output terminal of the electric current mirror circuit, which is made variable with a variable resistor for setting the I8 voltage, is connected to the reference input terminal of the comparison circuit, and the load resistance on the output side is A transformer for switching the reference voltage is connected in parallel with a part of the circuit, and the current mirror circuit constitutes a constant current source, so the change in load resistance on the output side changes the output current 1.
This has the advantage that the hysteresis width can be set independently of the detection reference voltage.
By using the constant electron source \'ref as the reference voltage of the current conversion circuit, there is an advantage that a distance setting voltage d greater than or equal to Vre can be obtained at the output end. By supplying current from a constant current source to part of the load resistor to switch to the return reference voltage, it is possible to reduce the voltage of the variable resistor at a point where noise is likely to be picked up, such as at the input end of the comparator circuit. It has the advantage of being able to avoid its use.

[Brief explanation of the drawing]

Fig. 1 is a detailed explanatory diagram of the present invention, Fig. 2 is a block circuit diagram showing an embodiment of the present invention, Fig. 3 is a specific circuit diagram of the same main part, and Fig. 1 is an implementation of the pond of the present invention. FIG. 5 is a circuit diagram of a conventional example. 1 is a projection optical system, 2 is a light receiving optical system, 3 is a light projection element, 4
a, 4b are light receiving elements, 5a, 5b are light receiving circuits, 6
a, 6b are λ/number amplification circuits, 7 is a differential amplification circuit, 8 is a comparison circuit, (j is an Iζ quasi-voltage generator, light spot,
N111i'・1. is a current mirror circuit, CT, , CT2
114LHji, −Electrical+Ai li conversion circuit, v R,
, VR, is a variable resistor, Vref is a return voltage source, DAl
i Differential amplifier, Q, , Q, , Q, ha) / Shimata Yu, Q4
is reference voltage switching trannostar, D is guioto, Rd
+ and Rb are load resistances. Figure 1 (b) Figure 2 Figure 5 Figure 9. Amendment to the examination procedure (voluntary) December 21, 1980 Mr. Commissioner of the Patent Office Yun: 61, Indication of the case 1982 Patent Application @224522 2, Name of the invention + 39 Kenchi no Takoden distance IC detection type photoelectric Switch (name change) 3, Relationship with the case of the person making the amendment Patent applicant Location 1048 Oaza Kadoma, Kadoma City, Osaka Name Name (583) Matsushita Electric Works Co., Ltd. Representative Iku Kobayashi 4, Attorney's Specification 8, Amendment Correction of the contents of the specification Japanese Patent Application No. 59-224522 1 Title of the invention Distance detection type charging switch 2 Claims: A calibration circuit is provided, and one reference voltage is connected to the input side via a resistance-current conversion circuit. Connect the output terminal of the optical mirror circuit connected to the variable resistor for setting to the reference input terminal of the above comparison circuit, and connect a reference voltage switching transistor in parallel to a part of the load resistance on the output side. Detailed Description of the Invention [Technical Field 1] This invention is characterized in that it is equipped with a reference voltage generating section that detects the presence of a detected object within a certain distance. This relates to a distance-sensing charging switch that detects whether the [Background Art 1 As shown in Fig. 1 b), the distance sensing type charging switch
The light emitting and receiving optical systems 1.2 are placed side by side at a predetermined distance from each other, and the light beam P emitted from the light emitting element 3 is diffusely reflected by the beam irradiation spot of the object to be detected X, and the reflected light R is When the light is focused by the light-receiving optical system 2, as shown in FIG. It detects whether the detected object X exists in the detection area,
As shown in Figure 2, the circuit configuration is such that the output currents of two light receiving elements 4a and 4b placed side by side in the light collecting plane are converted into signal voltages by light receiving circuits 5a and Sb, respectively, and the dynamic lens is further expanded. In order to do this, logarithmic conversion is performed in the logarithmic amplifier circuits 6a and 6b, and then input to the differential amplifier circuit 7, and the difference output is used as the signal input Vin of the comparator circuit 8, and the detection distance setting is inputted from the reference voltage generator 9. It is compared with the reference voltage Vd for use. Note that recently, two light receiving elements 4a, 4
In place of b, a three-terminal position sensing element (PSD) using a PIN photodiode is used. Conventionally, this reference/voltage generating section 9 has been constructed of a constant voltage source Vref and a variable resistor VR as shown in FIG. 5, which has the following drawbacks. (1) When converting the circuit into an IC, the constant voltage source Vref is normally suppressed to a value of 1 degree, but in this conventional circuit configuration, Vr
A distance setting voltage Vd greater than or equal to ef cannot be obtained. (2) Two external connection terminals a for connecting the variable resistor VR,
Since it requires b, it is disadvantageous for IC implementation. (3) In order to prevent repeated recovery due to disturbance buzz during detection, it is necessary to have a so-called hysteresis characteristic that switches to the reference voltage for recovery at the same time as detection, but this conventional circuit has a hysteresis characteristic. It is extremely difficult to construct a circuit to make the width variable. [Objective of the Invention 1 The present invention has been made in view of the above-mentioned problems, and its object is to provide a distance-sensing charging switch whose detection sensitivity has the above-mentioned hysteresis characteristic.
Particularly, it is an object of the present invention to provide a configuration of a reference voltage generation circuit that is suitable for use in ICs. [Disclosure 1 of the Invention The present invention provides a method in which a light receiver is disposed on the side of a beam projector, and the displacement of the imaging position of the beam irradiation spot by the light receiving optical system is detected as a difference signal between both outputs of the position detection type light receiving element. In a distance detection type charging switch that detects the distance to a detected object, a comparison circuit is provided to compare the difference signal with a distance setting reference voltage, and a resistor is connected to the input side.
The output terminal of the current mirror circuit, which is connected to a variable resistor for setting the reference voltage via the current conversion circuit, is connected to the reference input terminal of the comparison circuit, and a transistor for switching the reference voltage is connected to a part of the load resistance on the output side. A reference voltage generation section is provided by connecting the two in parallel, and the reference voltage is automatically switched at the same time as an object is detected to lower the return light reception level, providing detection sensitivity and hysteresis, and a current mirror circuit. The input terminal of the sensor is adjusted using a variable resistor for setting the detection distance, so that setting or changing the hysteresis width does not affect the detection reference voltage. FIG. 3 shows an embodiment of the present invention, in which a current mirror circuit M1 inputs the bases of input and output side transistors Q, Q2, which are formed on a single chinobu in common. Connected to the collector of side transistor Q,
A resistor-current conversion circuit CT is connected to the collector of the transistor Q1 on the input side. Variable resistor VR for setting the detection reference voltage through. is connected. The resistance-current conversion circuit CT is composed of a differential amplifier DA, a transistor Q controlled by its output, and a constant voltage source Vref.The emitter of the transistor Q is connected to the inverting input side of the differential amplifier 5DA, and A constant voltage source V ref is connected to each input side. In the above configuration, when the input current of the current mirror circuit M1 is changed by the resistance value of the variable resistor VR, the voltage fluctuation at the point d is fed back to the input of the differential amplifier DA ([11k), and is always at the point d. Since the voltage is controlled to be equal to Vrer, a current that is inversely proportional to the resistance value of the variable resistor VR can be obtained with high precision. A resistor Rd for setting the detection reference voltage Vd as a load resistance and a resistor Rh for setting the hysteresis width are connected in series, and the voltage of this output yac is used as the second detection reference voltage Vd. The reference voltage is applied to the reference input terminal of the comparator circuit 8 shown in FIG. The current mirror circuit M is formed on a single chip with a common base, and both transistors Q1 and Q2 are matched with each other, and the base current of the output transistor Q2 is the same as that of the diode-connected input transistor Q. Since it is defined by the base current, the same collector current as that of the input transistor Q1 always flows through the output side transistor Q2 and is not affected by the value of the load resistance.Therefore, the reference voltage switching transistor Q4 is determined by the object detection signal.
Even if on/off control is performed, the detection reference voltage setting resistor Rd
The voltage across both ends does not change, and by making the hysteresis width setting resistor Rh variable, the detection reference voltage and the hysteresis width can be adjusted independently without affecting each other. In reality, since the input impedance of the comparison circuit is extremely high, the output terminal C of the current mirror circuit M is likely to pick up noise, and it is extremely difficult to use a variable resistor as part of the load resistance. FIG. 4 shows an embodiment that improves this point. In the same figure, there is a resistance-current conversion circuit CT2 on the input side.
The output current I)l of the current mirror circuit M2 connected to the variable resistor VR for setting the hysteresis width is supplied to the resistor Rh for setting the hysteresis width via the diode D, and the output terminal e The above-mentioned hysteresis width switching transistor Q4 is connected between A constant current IN is supplied from the second constant current source, and this current value I,
can be adjusted by the variable resistor VR3 on the input side of the current mirror circuit M2, so there is no risk of noise being introduced to the input end of the comparison circuit, and moreover, the detection reference voltage and the hysteresis width can be set independently of each other. "Effects of the Invention" As described above, in the present invention, in a photoelectric switch that automatically switches to the base thread voltage for return when an object is detected, the input terminal can be made variable using a variable resistor for setting the detection reference voltage. The output terminal of the current mirror circuit is connected to the reference input terminal of the comparator circuit, and a reference voltage switching transistor is connected in parallel to a part of the load resistance on the output side.
Since the current mirror circuit constitutes a constant current source, changes in the load resistance on the output side do not affect the output current, which has the advantage that the hysteresis width can be set independently of the detection reference voltage. By using the constant voltage source Vre as the reference voltage of the conversion circuit, there is an advantage that a distance setting voltage Vd higher than Vref can be obtained at the output end. If you switch to the reset reference voltage by supplying current from a constant current source to part of the load resistor, it will be possible to avoid locations such as the input terminal of the comparator circuit where the input voltage is high and easily picks up noise. This has the advantage that the use of a variable resistor can be avoided. 4. Brief description of the drawings.
FIG. 2 is a block circuit diagram showing an embodiment of the present invention, FIG. 3 is a specific circuit diagram of the same essential parts as above, FIG. 4 is a specific circuit diagram of essential parts showing an embodiment of the pond of the present invention, and FIG. FIG. 2 is a circuit diagram of a conventional example. 1 is a light projecting optical system, 2 is a light receiving optical system, 3 is a light projecting element, 4a
, 4b is a light receiving element, 5a, 5b is a light receiving circuit, 6a
, 6b is a logarithmic amplifier circuit, 7 is a differential amplifier circuit, 8 is a comparison circuit, 9 is a reference voltage generator or an object to be detected, P is a light beam, R is reflected light, S is a focused spot, M port M2 is a current mirror circuit, CT2 is a resistance-current conversion circuit, VR
,,VR, are variable resistors, Vrer is a constant voltage source, DA is a differential amplifier, Q, ,Q, ,Q are transistors, Q is a reference voltage switching transistor, D is a diode, Rd,
Rh is load resistance.

Claims (1)

[Claims] (1) The comparison circuit compares the reflected light level from the liquid detection object with the detection reference voltage, and when it is detected that the detection object is within a set distance, the return reference voltage is automatically switched. In reflective photoelectric switches,
The output terminal of a current mirror circuit, which has a variable resistor for setting the detection reference voltage connected to the input side via a resistance-current conversion circuit, is connected to the reference input terminal of the above comparison circuit, and a part of the load resistance on the output side is connected to the reference input terminal of the comparison circuit. A reflective photoelectric switch characterized by having a reference voltage switching transistor connected in parallel to a transistor.