JP2021105552A - Position detection device - Google Patents

Abstract

To provide a position detection device that can bring a position detection signal to a value determined in advance in accordance with a position of a measurement body.SOLUTION: A position detection device includes: light-emitting means that generates light; a light-receiving element that generates two current signals according to a position where the light emitted from the light-emitting means is received; two conversion units that convert the two current signals into voltage signals; a subtraction unit that outputs a difference between the voltages output from the two conversion units as a position detection signal; an integration circuit that receives the input of the voltage based on the total voltage of the voltages output from the two conversion units and outputs the integral voltage obtained by integrating the input voltage; a transistor that has an input electrode to which the integral voltage is applied and causes the light-emitting means to generate light with the light intensity according to the integral voltage; and target voltage setting means that has a variable resistor capable of changing a resistance value and can set the voltage input to the integration circuit so as to become the voltage determined in advance.SELECTED DRAWING: Figure 1

Description

The present invention relates to a position detecting device.

For example, the position detecting device described in Patent Document 1 is configured as follows. That is, in a position detecting device having a light source and a semiconductor position detecting element arranged at a position capable of receiving light emission of the light source, the temperature detecting means for detecting the ambient temperature and the temperature detecting signal of the temperature detecting means are supported. It is characterized by including a reference signal generation circuit that outputs the reference signal, and a drive current control unit that controls the drive current of the light source based on the reference signal from the reference signal generation circuit.

Japanese Unexamined Patent Publication No. 02-112708

For example, in the position detection device described in Patent Document 1, in order to detect the position of the object to be measured with high accuracy, the position detection signal corresponding to the two currents corresponding to the light receiving position of the detection element is used for the object to be measured. It is desired that the value becomes a predetermined value according to the position.
An object of the present invention is to provide a position detection device capable of causing a position detection signal to have a predetermined value according to the position of an object to be measured.

The present invention completed for the above object has a light emitting means for generating light, a light receiving element for generating two current signals according to the position where the light emitted from the light emitting means is received, and the above two currents. Two conversion units that convert signals into voltage signals, a subtraction unit that outputs the difference between the voltages output from each of the two conversion units as a position detection signal, and a voltage output from each of the two conversion units. It has an integrator circuit that inputs a voltage that takes into account the added total voltage and outputs an integrated voltage that integrates the input voltage, and an input electrode to which the integrated voltage is applied, and the light emitting means responds to the integrated voltage. A target voltage setting means that has a transistor that generates light of a different luminosity, a variable resistor whose resistance value can be changed, and can be set so that the voltage input to the integrating circuit becomes a predetermined voltage. It is a position detection device provided with.
Here, the target voltage setting means includes a variable voltage unit that has the variable resistor and can adjust the voltage input to the integrating circuit, and a fixed voltage unit that inputs a fixed voltage to the integrating circuit. You may have it.

According to the present invention, it is possible to provide a position detection device capable of setting a position detection signal to a predetermined value according to the position of the object to be measured.

It is a figure which shows an example of the schematic structure of the position detection apparatus which concerns on embodiment. It is a figure which shows an example of the state which the light emitting part of a position detection apparatus and PSD are fixed. It is a figure which shows an example of the relationship between the position of a mover, and a voltage difference.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.
FIG. 1 is a diagram showing an example of a schematic configuration of a position detection device 1 according to an embodiment.
The position detecting device 1 includes a light emitting unit 10 that emits light, and a semiconductor position detecting element 20 that is arranged so as to face the light emitting unit 10.

It can be exemplified that the light emitting unit 10 is a light emitting diode (LED (Light Emitting Diode)) or a laser.
It can be exemplified that the semiconductor position detection element 20 is a spot light position detection sensor that utilizes the surface resistance of a photodiode. Hereinafter, the semiconductor position detection element 20 may be referred to as “PSD20”. The PSD 20 is an element in which the current output from each electrode changes depending on the resistance proportional to the distance from the incident position of the light from the light emitting unit 10 to the electrodes provided at both ends.

Further, the position detection device 1 uses a current-voltage conversion circuit 31 that converts an output current Ia output from one end of the PSD 20 into a voltage Va, and a voltage Vb that converts the output current Ib output from the other end of the PSD 20 into a voltage Vb. It is provided with a current-voltage conversion circuit 32 for converting to.
Further, the position detection device 1 includes a subtraction unit 40 that subtracts the voltage Va output from the current-voltage conversion circuit 31 from the voltage Vb output from the current-voltage conversion circuit 32. The subtraction unit 40 outputs a voltage difference ΔV (= Vb−Va) obtained by subtracting the voltage Va from the voltage Vb as a position detection signal.

Further, the position detection device 1 has a luminous intensity adjusting unit 50 that adjusts the luminous intensity of the light emitting unit 10.
The luminous intensity adjusting unit 50 includes a transistor 60 that controls the current flowing through the light emitting unit 10, and an integrating circuit 70 that applies a voltage to the base 61 of the transistor 60. Further, the position detection device 1 includes a target voltage setting unit 80 for setting a target voltage applied to the integrating circuit 70. Further, the position detection device 1 includes a voltage application unit 90 that applies a voltage corresponding to the voltage Va output from the current-voltage conversion circuit 31 and the voltage Vb output from the current-voltage conversion circuit 32 to the integration circuit 70. , Is equipped.

In the transistor 60, the emitter 62 is connected to the light emitting unit 10, and the collector 63 is connected to the positive power supply voltage Vcc.
The integrating circuit 70 includes an amplifier 71, a diode 72, and a capacitor 73. The non-inverting input terminal of the amplifier 71 is grounded. Then, a voltage obtained by adding the output voltage from the voltage application unit 90 and the voltage set by the target voltage setting unit 80 is applied to the inverting input terminal of the amplifier 71.

The target voltage setting unit 80 is connected to a reference voltage circuit 81 in which one end outputs a constant positive voltage Ve and a reference voltage circuit 82 in which the other end outputs a constant negative voltage −Ve. The variable resistor 83 is provided so that the ratio between the resistance value on one end side and the resistance value on the other end side can be changed by operating from the outside. Further, the target voltage setting unit 80 has a confluence point 84 with the output voltage from the voltage application unit 90 and a resistor 85 provided between the variable resistor 83. Further, the target voltage setting unit 80 has a reference voltage circuit 86 having one end connected to a constant negative voltage −Ve, and a resistor 87 having the other end connected to the integrating circuit 70.
The target voltage setting unit 80 sets a predetermined negative voltage as the target voltage Vm.

One end of the voltage application unit 90 is connected to the current-voltage conversion circuit 31 via a resistor 91, the other end is connected to the current-voltage conversion circuit 32 via a resistor 92, and a resistor is externally connected. It has a variable resistor 93 whose value can be changed.
Hereinafter, the output voltage of the output terminal 94, which is a terminal provided between both terminals of the variable resistor 93 of the voltage application unit 90, may be referred to as Vc.
The output voltage Vc is a positive voltage based on the total voltage of the voltage Va output from the current-voltage conversion circuit 31 and the voltage Vb output from the current-voltage conversion circuit 32.

In the position detecting device 1 configured as described above, the input voltage of the integrating circuit 70 of the luminous intensity adjusting unit 50 is the output voltage Vc of the voltage applying unit 90 and the target voltage set by the target voltage setting unit 80. Based on the voltage Vt.
In the state immediately after the initial setting of the position detection device 1 (initial state), the absolute value of the output voltage Vc of the voltage application unit 90 is equal to the absolute value of the target voltage Vm set by the target voltage setting unit 80. As a result, the voltage Vt is set to zero (0 (V)).
From the initial state, the absolute value of the output voltage Vc of the voltage application unit 90 changes, and the absolute value of the output voltage Vc of the voltage application unit 90 is smaller than the absolute value of the target voltage Vm set by the target voltage setting unit 80. Then, the voltage Vt is a large value corresponding to the difference (| Vm |-| Vc |) between the absolute value of the output voltage Vc of the voltage application unit 90 and the absolute value of the target voltage Vm set by the target voltage setting unit 80. It becomes a negative voltage.
On the contrary, the absolute value of the output voltage Vc of the voltage application unit 90 changes from the initial state, and the absolute value of the output voltage Vc of the voltage application unit 90 is the absolute value of the target voltage Vm set by the target voltage setting unit 80. When the voltage Vt becomes larger than, the voltage Vt becomes the difference (| Vc |-| Vm |) between the absolute value of the output voltage Vc of the voltage application unit 90 and the absolute value of the target voltage Vm set by the target voltage setting unit 80. It becomes a positive voltage of a corresponding magnitude.
The factor that causes the absolute value of the output voltage Vc to change in this way is, for example, a temperature change or a secular change of the position detection device 1.

The voltage applied to the base 61 of the transistor 60 is a voltage obtained by integrating the voltage Vt, which is the input voltage of the integrating circuit 70, with respect to time, and the sign is converted from negative to positive or positive to negative (the sign is inverted). It is a voltage. Then, the light emitting unit 10 generates light by a current corresponding to the voltage applied to the base 61 of the transistor 60. The luminous intensity of the light generated by the light source unit 10 increases as the voltage applied to the base 61 of the transistor 60 increases, and decreases as the voltage applied to the base 61 of the transistor 60 increases.
Then, the output current Ia and the output current Ib from the PSD 20 have a magnitude corresponding to the luminous intensity of the light from the light emitting unit 10.

Further, when the luminous intensity of the light from the light emitting unit 10 increases, the output current Ia and the output current Ib from the PSD 20 increase, and the input voltage Vt of the integrating circuit 70 increases, so that the voltage applied to the base 61 of the transistor 60 increases. Becomes smaller. On the contrary, when the light intensity of the light from the light emitting unit 10 becomes small, the output current Ia and the output current Ib from the PSD 20 decrease, and the input voltage Vt of the integrating circuit 70 becomes small, so that the light is applied to the base 61 of the transistor 60. The voltage increases.
As a result, the voltage applied to the base 61 of the transistor 60 is automatically adjusted, and the luminous intensity of the light from the light emitting unit 10 is automatically adjusted so as to have a predetermined luminous intensity.
By these operations, the input voltage Vt of the integrating circuit 70 is automatically adjusted to always be zero (0 (V)). In other words, the voltage Va output from the current-voltage conversion circuit 31 and the voltage Vb output from the current-voltage conversion circuit 32 are automatically adjusted so as to always be appropriate voltages.
Therefore, the position detecting device 1 can detect the position of the object to be measured with high accuracy without being affected by the temperature change and the aging change.

FIG. 2 is a diagram showing an example of a state in which the light emitting unit 10 and the PSD 20 of the position detection device 1 are fixed.
In the position detection device 1, the substrate on which the light emitting unit 10 is mounted is fixed to the mover 101 of the linear motor 100, the board on which the PSD 20 is mounted is fixed to the stator 102 of the linear motor 100, and the mover with respect to the stator 102. It can be exemplified to detect the position of 101.

FIG. 3 is a diagram showing an example of the relationship between the position x of the mover 101 and the voltage difference ΔV. As shown in FIG. 2, the position x is the distance between the electrical center of the PSD 20 and the incident position of the light from the light emitting unit 10.
When light from the light emitting unit 10 is incident on the PSD 20, an electric charge proportional to the amount of light is generated at the incident position. This charge reaches the resistance layer as a photocurrent, is divided in inverse proportion to the distance to each electrode, and is taken out by the output electrode.
The relationship between the incident position of light and the current of the output electrode is as shown in the following equation (1).
Va × (L−x) = Vb × (L + x) ・ ・ ・ (1)
L is the resistance length of the PSD 20.

The resistance value obtained by adding the resistance value of the resistor 91 and the resistance value between one end of the variable resistor 93 and the output terminal 94 is defined as R1. Further, the resistance value obtained by adding the resistance value of the resistor 92 and the resistance value between the other end of the variable resistor 93 and the output terminal 94 is defined as R2.
The output voltage Vc of the output terminal 94 is as shown in the following equation (2).
Vc = (R2 x Va + R1 x Vb) / (R1 + R2) ... (2)
Here, in the luminous intensity adjusting unit 50, as described above, the luminous intensity of the light emitting unit 10 is feedback-controlled so that the output voltage Vc becomes constant. Therefore, for convenience of calculation, if the constant is set to 1, the following equation ( 3) holds.
Vc = (R2 x Va + R1 x Vb) / (R1 + R2) = 1 ... (3)

When Va and Vb are obtained by the formulas (1) and (3), Va is as shown in the following formula (4) and Vb is as shown in the following formula (5).
Va = (L + x) / (L + xx (R2-R1) / (R1 + R2)) ... (4)
Vb = (L-x) / (L + xx (R2-R1) / (R1 + R2)) ... (5)

Then, the voltage difference ΔV is as shown in the following equation (6).
ΔV = Vb-Va = -2x / (L + xx (R2-R1) / (R1 + R2)) ... (6)
According to the equation (6), when R1 = R2, ΔV = -2x / L, so that the voltage difference ΔV is completely proportional to the position x of the mover 101.
Therefore, as shown in FIG. 3, the voltage difference ΔV and the mover 101 are adjusted by adjusting the position of the output terminal 94 of the variable resistor 93, in other words, the resistance value between the terminals so that R1 = R2. It is possible to make the relationship between the position x and the position x a linear relationship.

For example, when assembling the position detection device 1 to the linear motor 100, the operator can exemplify the following.
For example, a jig capable of moving the mover 101 by 1 (mm) with respect to the stator 102 by applying 1 (V) is used.
Then, using this jig, the voltage difference ΔV1 when 1 (V) is applied and the voltage difference ΔV2 when 2 (V) is applied are in a proportional relationship (ΔV1 = ΔV2 / 2) between the terminals. It is good to change the resistance value of.

As described above, according to the position detection device 1, even if the resistance value of the resistor 91 and the resistance value of the resistor 92 are different due to the individual difference between the resistor 91 and the resistor 92, the distance between the terminals of the variable resistor 93 By changing the resistance value, R1 = R2 can be set. Therefore, according to the position detection device 1, it is possible to make the relationship between the voltage difference ΔV and the position x linear with high accuracy as compared with the configuration without the variable resistor 93. .. As a result, according to the position detection device 1, the position of the mover 101, which is the object to be measured, can be detected with high accuracy.

Further, according to the position detection device 1 according to the embodiment, the luminous intensity of the light from the light emitting unit 10 is defined by the output voltage Vc of the voltage application unit 90 and the target voltage set by the target voltage setting unit 80. Will be done.
The target voltage setting unit 80 has a variable resistor 83 capable of changing the ratio of the resistance value on one end side to the resistance value on the other end side, that is, the resistance value between terminals. There is. Therefore, for example, an operator who assembles the position detection device 1 to the linear motor 100 can adjust the luminous intensity of the light from the light emitting unit 10 by doing the following.

That is, the operator uses a jig capable of moving the mover 101 by 1 (mm) with respect to the stator 102 by applying 1 (V). Then, the operator uses this jig to apply 1 (V) between the terminals of the variable resistor 83 so that the voltage difference ΔV becomes a predetermined predetermined value (for example, 1 (V)). It is good to change the resistance value of. As described above, according to the position detection device 1 according to the embodiment, for example, the voltage difference ΔV when the mover 101 moves by a predetermined value (for example, 1 (mm)) with respect to the stator 102 is a specified value (for example). It can be adjusted with high accuracy so that it becomes 1 (V)).

Further, the target voltage setting unit 80 has a variable resistor 83 whose resistance value can be changed from the outside, and in addition to the variable voltage unit in which the voltage input to the integrating circuit 70 can be adjusted, the reference voltage circuit 86 and the resistance It has 87 and is provided with a fixed voltage unit for inputting a fixed voltage to the integrating circuit 70. As a result, for example, even when the resistance value of the variable resistor 83 is manipulated and the voltage applied to the resistor 85 becomes the largest, the voltage input to the integrating circuit 70 becomes an unstable voltage. Is suppressed. As a result, according to the position detection device 1 according to the embodiment, light can be stably emitted from the light emitting unit 10 as compared with a configuration having no reference voltage circuit 86 and a resistor 87.

As described above, the position detection device 1 generates two current signals, one is a light emitting unit 10 as an example of the light emitting means for generating light, and the other is a position corresponding to the position where the light emitted from the light emitting unit 10 is received. The PSD 20 is provided as an example of the light receiving element. Further, the position detection device 1 includes a current-voltage conversion circuit 31 and a current-voltage conversion circuit 32, and a current-voltage conversion circuit 31 and a current-voltage conversion circuit as examples of two conversion units that convert two current signals into voltage signals, respectively. A subtraction unit 40 that outputs a voltage difference ΔV of the voltage output from each of the 32 as a position detection signal is provided. Further, the position detection device 1 is input with a voltage Vt in which the total voltage (Va + Vb) obtained by adding the voltages from the current-voltage conversion circuit 31 and the current-voltage conversion circuit 32 is added, and the integrated voltage obtained by integrating the input voltage Vt. It has an integrator circuit 70 that outputs an integrated voltage, a base 61 as an example of an input electrode to which an integrated voltage is applied, and a transistor 60 that generates light having a luminosity corresponding to the integrated voltage in the light emitting unit 10. .. Further, the position detecting device 1 has a variable resistor 83 whose resistance value can be changed from the outside, and is a target voltage setting means capable of setting the voltage input to the integrating circuit 70 to be a predetermined voltage. The target voltage setting unit 80 is provided as an example.

According to the position detection device 1 configured in this way, the accuracy is high as compared with the configuration without the variable resistor 83, and the position detection signal depends on the position of the object to be measured (for example, the mover 101). It can be set to a predetermined value. Therefore, according to the position detection device 1, the position of the object to be measured can be detected with high accuracy.

Here, the target voltage setting unit 80 is used in the reference voltage circuits 81 and 82, the variable resistor 83 and the resistor 85, and the integrator circuit 70 as an example of the variable voltage unit in which the voltage input to the integrator circuit 70 can be adjusted. A reference voltage circuit 86 and a resistor 87 are provided as an example of a fixed voltage unit for inputting a fixed voltage. As a result, the light emitting unit 10 can stably emit light.

In the position detection device 1, the resistance value of the resistance 91 of the voltage application unit 90 is 10 k (Ω), the resistance value of the resistance value 92 is 10 k (Ω), and the resistance value (adjustment range) of the variable resistor 93 is 0 to 500. (Ω), the resistance value of the resistance 85 of the target voltage setting unit 80 is 100 k (Ω), the resistance value of the resistance 87 is 20 k (Ω), and the resistance value (adjustment range) of the variable resistor 83 is 0 to 10 k. It can be exemplified that (Ω) and the voltage Ve are 10 (V).

1 ... position detection device, 10 ... light emitting unit, 20 ... semiconductor position detection element, 31 ... current / voltage conversion circuit, 32 ... current / voltage conversion circuit, 50 ... photometric adjustment unit, 60 ... transistor, 61 ... base, 62 ... emitter, 63 ... Collector, 70 ... Integrator circuit, 80 ... Target voltage setting unit, 83 ... Variable resistor, 85, 87 ... Resistance, 86 ... Reference voltage circuit, 90 ... Voltage application unit, 93 ... Variable resistor

Claims (2)

Light emitting means to generate light and
A light receiving element that generates two current signals according to the position where the light emitted from the light emitting means is received, and a light receiving element.
Two converters that convert the two current signals into voltage signals, respectively.
A subtraction unit that outputs the difference in voltage output from each of the two conversion units as a position detection signal, and a subtraction unit.
An integrator circuit that outputs an integrated voltage that is obtained by inputting a voltage that takes into account the total voltage obtained by adding the voltages output from each of the two conversion units and integrating the input voltage.
A transistor having an input electrode to which the integrated voltage is applied and causing the light emitting means to generate light having a luminous intensity corresponding to the integrated voltage.
A target voltage setting means that has a variable resistor whose resistance value can be changed and can be set so that the voltage input to the integrating circuit becomes a predetermined voltage.
A position detector comprising. The target voltage setting means has the variable resistor and includes a variable voltage unit that can adjust the voltage input to the integrating circuit and a fixed voltage unit that inputs a fixed voltage to the integrating circuit. The position detection device according to claim 1.

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