JPH03248013A - Position detecting apparatus - Google Patents

Abstract

PURPOSE:To eliminate the drift of temperature by compensating the temperature drift caused by a mechanism part with a correcting circuit for the mechanism part, and compensating the temperature drift caused by a semiconductor position detecting element with a correcting circuit for the element. CONSTITUTION:A position signal is obtained from a detected signal which is outputted from the end-part electrode of a semiconductor position detecting element 1 and corresponds to the illuminated position at a light receiving surface. At this time, the signal is detected with a first temperature detecting means 9. Correction is applied on the position signal from the element 1 in a correcting circuit 11 for a mechanism part based on the temperature of the mechanism part. Thus, the drift of temperature caused by the mechanism part which is uniformly included under certain temperature conditions is removed. Furthermore, the temperature of the element 1 is detected with a second temperature detecting means 12. Correction is performed, in an element correction circuit 13 by the amount of the correction determined by the detected temperature and the position signal from the element 1. At this time, the level of the position signal corresponds to the illuminated position on the element 1. Therefore, the amount of the correction is determined by the temperature of the element 1 and the illuminated position after all.

Description

[Detailed Description of the Invention] <Industrial Application Field> A position detection device using a semiconductor device detection element (PSD) is used as a device for measuring minute amounts of displacement, compressive load, tension, torque, etc. be.

The present invention relates to the above-mentioned position detection device, and more particularly to the configuration of a processing circuit portion of a detection output of a semiconductor device detection element.

<Prior Art> FIGS. 5 and 6 show the circuit configuration of a conventional position detection device of this type.

First, in FIG. 5, Ol is a semiconductor device detection element, 0
Reference numeral 2 denotes a light source such as a light emitting diode placed opposite to the semiconductor device detection element O1, and the light emitted from this light source 02 is condensed to a small size by a light convergence means such as a slit 03 in front of the light source 2, and is focused on the semiconductor device detection element O1. The light is irradiated onto the light receiving surface.

Further, 04 and 05 are photocurrents taken out from each electrode at both ends of the semiconductor device detection element 01! , , I', into voltage signals V , , V , respectively, 06 is the difference Vo between the outputs of both types of current/voltage converters 04 and 05.
("V t V +), 07 is an adder that adds the outputs V + and V t of both current/voltage converters 04 and 05, and 08 is an adder that adds the difference signal V from the subtracter 06. The output of the normalization circuit 08 is taken out as a position signal.

The conventional device shown in FIG. 6 omits the normalization circuit 08 and controls the light emission of the light source 02 by feeding back the entire output of the semiconductor device detection element O1. 09 is a constantization circuit that generates a light emission control signal such that the output of the adder 07 is constant from the output of the adder 07 and a preset reference value, and 010 is a constantization circuit that generates a light emission control signal from the constantization circuit 09. This is a drive circuit that controls light emission from the light source 02.

The other configurations are the same as those in FIG.

In this example, the difference signal V is the output of subtractor 06.

is taken out as a position signal, but the output V of one current/voltage converter 04 may be taken out as it is as a position signal.

<Problems to be Solved by the Invention> In the conventional device shown in FIG. 5, normalization processing is performed on the detection output of the semiconductor device detection element 01. Even if there is some variation, the adverse effects of the variation can be removed, but there is a problem in that the provision of the normalization circuit 08 complicates the overall circuit configuration.

The device shown in FIG. 6 addresses this problem of complicating the circuit configuration, and compared to the device shown in FIG. Only the circuit 09 and the drive circuit 吾0 are required, which greatly simplifies the circuit configuration.

However, the device shown in FIG. 6 has a problem in that the position signal obtained therefrom includes considerable temperature drift.

To deal with this, it has been considered to install a new means to detect the ambient temperature and control the light emission of light source 02 under conditions that take the ambient temperature into account, but this does not improve the temperature characteristics sufficiently. .

By the way, when the inventor of the present invention measured the detection output of the device shown in FIG. 6 at several positions of the semiconductor device detection element 01 under different temperature conditions, a temperature characteristic line as shown in FIG. 7 was obtained. It was done. In FIG. 7, the vertical axis represents the voltage value of the output obtained from either end of the semiconductor device detection element O1 (in this case, Vt in FIG. 6), and the horizontal axis represents the temperature. Each characteristic line is the same as the measured value at 5°C measured at the same position on the light-receiving surface of the semiconductor device detection element.
The values measured at 5°C are connected. Here, 25℃
The vertical lines shown next to the dot series of measured values in , indicate the positions on the light-receiving surface of the semiconductor device detection element where the measured values on each characteristic line were obtained.

For comparison, Fig. 8 shows an ideal temperature characteristic line drawn in the same way as Fig. 7. In this way, the output voltage v1
If it depends only on the position on the semiconductor device detection element 01, that is, if there is no slope in the temperature characteristic line, accurate measurement without temperature drift can be performed.

Now, the first thing to notice when examining the temperature characteristic line in FIG. The temperature gradient of the measured value becomes steeper as it approaches , and the degree of steepness is approximately symmetrical with respect to the center of the element O1.

Such a tendency of temperature characteristics can be seen in the semiconductor device detection element 01.
Since it corresponds to the position of , it is clear that this is caused by the element itself. Therefore, by detecting the temperature of the semiconductor device detection element 01 and making some kind of correction based on the detected temperature, the above-mentioned tendency can be eliminated and the temperature characteristics
You should be able to get it close to the one in the picture.

Also, the second point you notice when considering the temperature characteristics in Figure 7 is:
As can be seen from the slope of the characteristic line including the measured value at the center point of element 01 with respect to the horizontal axis, the characteristic line has an upward slope to the right and a downward slope to the right with the boundary near the center of semiconductor device detection element O1 in the figure. It is almost symmetrical. That is, as the temperature rises, the former tends to increase the output amount, and the latter tends to decrease the output amount.

In this way, if the same tendency appears for all characteristic lines, this tendency is not caused by some parts such as the semiconductor device detection element 01 or the light source 02, but by the fact that these parts are attached. This is thought to be caused by the entire mechanism. In fact, when we measured position detection devices with different mechanical configurations, all of the characteristic lines included the same temperature gradient, but the magnitude and direction of the temperature gradient were different from those shown in FIG.

It is thought that the tendencies included in any of the characteristic lines can be eliminated by detecting the temperature of the mechanical part and correcting it based on the detected temperature.

The present invention has been made based on the above findings, and provides a position detection device that controls the light emission of a light source by feeding back the entire output of a semiconductor device detection element.
The objective is to eliminate the temperature drift contained in the position signal.

<Means for Solving the Problems> In order to achieve the above-mentioned problems, the present invention provides a semiconductor device detection element, a light source that irradiates a light receiving surface of the semiconductor device detection element, and a total output power of the semiconductor device detection element. A position detection device having a circuit for controlling light emission of a light source so that the temperature is constant, a first temperature detection means for detecting the temperature of at least a mechanical part to which the light source is attached, and an output of the first temperature detection means. a correction circuit for a mechanism section that compensates for temperature drift caused by the mechanism section by correcting the position signal from the semiconductor device detection element with a correction amount determined by the correction amount; and a second temperature detection circuit that detects the temperature of the semiconductor device detection element. means and this second
and a correction circuit for an element that compensates for temperature drift caused by the semiconductor device detection element by correcting the position signal with a correction amount determined by the output of the temperature detection means and the position signal from the semiconductor device detection element. And so.

Effect> In the above configuration, a detection signal corresponding to the irradiation position on the light receiving surface is output from the end electrode of the semiconductor device detection element, and a position signal is obtained from this detection signal. 1. The temperature of the mechanical section is detected by the temperature detecting means, and a correction circuit for the mechanical section corrects the position signal from the element based on the detected temperature. This eliminates the temperature drift caused by the mechanism, which is uniformly included in the position signal corresponding to any position of the element under a certain temperature condition.

Further, the temperature of the semiconductor device detection element is also detected by the second temperature detection means, and a correction circuit for the element performs correction using a correction amount determined by the detected temperature and the position signal from the element. In this case, since the level of the position signal, which is one element that determines the amount of correction, corresponds to the irradiation position on the element, the amount of correction ultimately depends on the temperature of the semiconductor device detection element,
It is determined by the irradiation position. Correction using this correction amount removes temperature drift caused by the semiconductor device detection element.

<Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

Figures 1 to 3 relate to the first embodiment of the present invention.
The figure is a circuit diagram of the entire device, and FIGS. 2 and 3 are temperature characteristic diagrams for explaining the operation.

In FIG. 1, l is a semiconductor device detection element, 2 is a light source that irradiates the light receiving surface of this semiconductor device detection element l, and 3 is a light shielding body that blocks the irradiation light from the light source 2, and these constitute a detection portion.

4.5 is the photocurrent 1.5 taken out from each electrode at both ends of the semiconductor device detection element l. ．． I, respectively, are voltage signals V
, , V, a pair of current/voltage converters, 6 is an adder that adds the output v1゜, of both types of current/voltage converter 4.5, and 7 is preset as the output of adder 6. 8 is a constantization circuit that generates a light emission control signal such that the output of the adder 6 is constant based on the reference value given by the constantization circuit 7; .

Then, the current/voltage converter 4.5 of the dual type current/voltage converter 4.5
The output V of the voltage converter 4 is temperature-corrected and then taken out as a position signal. The components involved in the temperature correction include a first temperature detection means 9, a correction signal generation circuit 10, a first correction circuit 11, a second temperature detection means 12, and a second temperature detection means 12.
There is a correction circuit 13.

The first temperature detection means 9 is composed of, for example, a thermistor,
The temperature of a mechanical part to which the light source 2 and the semiconductor device detection element 1 are attached, in this example, a member 14 to which the light source 2 is attached is detected. The correction signal generation circuit 10 generates a correction signal S corresponding to the detection output T of the first temperature detection means 9, and in this embodiment is constituted by a differential amplifier 10a.

The first correction circuit 11 corrects the output v1 of one of the current/voltage converters 4 using the correction signal S from the correction signal generation circuit 1O to compensate for temperature drift caused by the mechanical part. In the illustrated example, the first correction circuit 11 is mainly composed of a differential amplifier 11a, and the output Vl of the current/voltage converter 4 is inputted to its negative input terminal together with the feedback voltage signal, and its positive input terminal is inputted to the first correction circuit 11. The correction signal SI is bias resistor 1
5 and is biased at Ov, and in addition to performing the above-mentioned correction, the output V1 of the current/voltage converter 4 is converted into a signal centered on Ov. I6 is a feedback resistor.

Further, the second temperature detection means I2 is composed of, for example, a thermistor, and detects the temperature of the semiconductor device detection element 1. The second correction circuit 3 corrects the position signal by a correction amount determined by the detection signal T of the second temperature detection means 12 and the position signal from the semiconductor device detection element 1, and corrects the position signal caused by the semiconductor device detection element 1. This is to compensate for temperature drift. In the illustrated example, the second correction circuit 13 is mainly composed of an inverting amplifier 13a, the output of the first correction circuit 11 is input to its positive input terminal, and the detection of the second temperature detection means 12 is input to its negative input terminal. The output T is input together with the feedback signal. 1
7 is a feedback resistor.

The operation and effects of the above configuration will be explained with reference to FIGS. 2 and 3.

When the light emitted from the light source 2 is applied to any position on the light-receiving surface of the semiconductor device detection element 1, a photocurrent 1. ．． I, flows, and this photocurrent 1. ．． I, is converted into a voltage signal V,,V, by a current/voltage converter 4.5.

Here, the amount of light received by the semiconductor device detection element l is determined by the adder 6,
- Since it is controlled to always be constant by the chemotaxis circuit 7 and drive circuit 8, the detection output (V+ in the illustrated example) from one end of the semiconductor device detection element 1 can be treated as a position signal. That is, V, +V, -C (= constant)
・・・・・・・・・・・・(1) V, -C-V,
・・・・・・・・・・・・(2) Vo
=V* V+=(CV+) Vt=(, -2V,
This is because (3) is obtained.

On the other hand, the detection output
It is corrected by the correction circuit 13.

First, in the mechanical section, the temperature of the mechanical section is detected by the first temperature detection means 9, and a correction signal SI corresponding to this detection signal T1 is generated by the correction signal generation circuit IO. And number one! In the correction circuit 11, the output (2) of the current/voltage converter 4 is corrected by this correction signal Sl.
The above-mentioned correction signal SL corresponds only to the temperature of the mechanical part and has no relation to the irradiation position on the semiconductor device detection element 1 at all.゛Therefore, the amount of correction in the first correction circuit If is constant regardless of the irradiation position on the element 1, provided that the temperature conditions of the mechanism are the same, and the position signal at each position of the element 1 is Corrected uniformly.

In terms of the temperature characteristic diagram, this correction corrects the tendency of the characteristic line shown in FIG. This is to correct the shape so that it is symmetrical about the center point. The amount of correction is the amount that makes the slope of the characteristic line of the measured value at the center point of the element 1 zero, as shown by hatching in FIG. This correction removes temperature drift caused by the mechanism.

The position signal corrected by the first correction circuit 11 is input to the second correction circuit 13, and is amplified by the inverting amplifier 13a. The detection signal T of the second temperature detection means 12 corresponding to the temperature of the semiconductor device detection element 1 and the feedback voltage signal from the output side of the inversion amplifier 13a are input to the negative input terminal of the inversion amplifier 13a. The amplification factor of the position signal of the inverting amplifier 13a is determined by the amount of addition of these two signals. Here, the level of the feedback voltage signal of the inverting amplifier 13a is
It corresponds to the level of the position signal input to 3a,
Since the level of the position signal corresponds to the irradiation position of the element 1, the amplification factor of the inverting amplifier 13a is ultimately determined by the temperature of the semiconductor device detection element 1 and the irradiation position on the element 1. By being amplified with such an amplification factor, the input position signal is corrected in accordance with the temperature of the semiconductor device detection element l and the irradiation position on the element l.

In this case, the farther the irradiation position is from the center point of element l, the larger the correction amount is, and the setting is such that with respect to the center point, correction is performed in the increasing direction on the one hand, and correction in the decreasing direction on the other hand. , semiconductor device detection element] is removed.

In terms of the temperature characteristic diagram, this correction involves correcting each of the characteristic lines that have symmetrical slopes with respect to the center point of element 1 as shown in Fig. 2 using the correction amounts shown in Fig. 3. The goal is to eliminate temperature gradients in each characteristic line. The amount of correction to each position signal is shown by hatching in FIG. 3, and increases or decreases as the irradiation position moves away from the center point or as the temperature moves away from the reference temperature.

As described above, the first correction circuit 11 compensates for the temperature drift caused by the mechanism, and the second correction circuit 13 compensates for the temperature drift caused by the semiconductor device detection element l. A position signal without temperature drift is obtained from the circuit 13.

In the embodiment shown in FIG. 1, the correction signal generation circuit 10
Even if the correction signal S is not applied to the first correction circuit 11 but is added to the output of the second correction circuit 13, the same temperature drift compensation effect as described above can be obtained. In this case, since only the bias voltage is applied to the positive input terminal of the differential amplifier lla of the first correction circuit 11, this circuit 11 converts the output vI of the current/voltage converter 4 into a signal centered on OV. It operates only as a converting circuit.

FIG. 4 is a circuit diagram of the second embodiment.

In this embodiment, the summer correction circuit I■ is omitted, and a new output VI of a pair of current/voltage converters 4.5 is provided.

■, the difference V. A subtractor 18 is provided which takes .

Then, a correction signal S is added to the output v0 of the subtracter 18, thereby compensating for the temperature drift caused by the mechanical part. Other circuit parts are the same as those in the embodiment of FIG.

In this embodiment as well, the correction signal S1 of the correction signal generation circuit 10 may not be applied to the output side of the subtracter 18, but may be added to the output of the second correction circuit 13.

In each of the above embodiments, various structures can be adopted for the detection portion. Usually, a structure is adopted in which the semiconductor device detection element 1 and the light source 2 are fixed to each other in a fixed positional relationship, and the light shield 3 is movable with respect to both the semiconductor device detection element 1 and the light source 2.

In this case, the light source 2 irradiates a wide area with parallel light.

It is something. Then, due to the movement of the light shield 3, the area of the irradiation area on the light receiving surface of the semiconductor device detection element 1 expands or contracts, and the amount of displacement of the light shield 3, etc. is detected by the change in the detection signal accompanying the expansion or contraction.

In addition, (a) semiconductor device detection element I or light source 2
One of them is attached to a member on the fixed side, the other is attached to a member on the movable side, and a structure in which a convergence means such as a lens or a slit is provided on the light source 2 side, (b) semiconductor device detection element l
It is possible to adopt a structure in which the light source 2 and the light source 2 are fixed to each other, and the slit is movable with respect to both.

In each of the above embodiments, a one-dimensional semiconductor device detector element is used.
71 was used, but a two-dimensional one can also be used, and in that case, another set of signal processing circuits on the output side of the element 1 will be required.

<Effects of the Invention> As described above, according to the present invention, the correction circuit for the mechanical part compensates for temperature drift caused by the mechanical part, and the correction circuit for the element compensates for the temperature drift caused by the mechanical part. Since the resulting temperature drifts are compensated for, accurate measurements without temperature drifts are obtained.

[Brief explanation of drawings]

1 to 3 relate to an embodiment of the present invention, in which FIG. 1 is a circuit diagram of the entire device, FIGS. 2 and 3 are characteristic diagrams for explaining the operation, and FIG. FIG. 3 is a circuit diagram of a second embodiment. 5 and 6 are circuit diagrams of conventional examples, FIG. 7 is a characteristic diagram of the conventional example of FIG. 6, and FIG. 8 is a characteristic diagram of an ideal model. l...Semiconductor device detection element, 2...Light source, 6...
Adder, 7... Fixed circuit, 8... Drive circuit, 9.
...first temperature detection means, 10...correction signal generation circuit,
11... first correction circuit (mechanism section correction circuit), 12.
...Second temperature detection means, ■3...Second correction circuit (element correction circuit).

Claims (1)

[Claims] (1) A position detection device having a semiconductor position detection element, a light source that illuminates the light receiving surface of the semiconductor position detection element, and a circuit that controls light emission of the light source so that the total output of the semiconductor position detection element is constant. At least a first temperature detection means for detecting the temperature of a mechanical part to which the light source is attached; and a position signal from the semiconductor position detection element corrected by a correction amount determined by the output of the first temperature detection means to correct the position signal from the semiconductor position detection element. a correction circuit for the mechanical part that compensates for temperature drift caused by the semiconductor device; a second temperature detection means for detecting the temperature of the semiconductor position detection element; A position detection device comprising: a correction circuit for an element that corrects the position signal with a correction amount determined by the position signal to compensate for temperature drift caused by the semiconductor position detection element.