JPH02247504A - Optical position detecting device - Google Patents

Abstract

PURPOSE:To improve measurement accuracy without varying signal intensity abruptly by detecting the incidence position of light according to the digital values of signals of the sum and difference from an A/D converter which are switched by a switching means. CONSTITUTION:Amplifiers 82 - 87 of a signal processing circuit constitute an amplifier 103 and comparators 88 - 91 and a priority encoder 92 constitute a selecting means 104 on the whole. Further, selectors 101 and 102 constitute the switching means 105. The digital signals of the sum and difference which are selected by the selectors 101 and 102 are inputted to a digital dividing circuit (optical position detecting means) and the dividing circuit divides the difference (numerator) by the sum (denominator) and outputs the result as a position signal. Therefore, signals which differ in gain are not switched by an analog switch, so even if an analog signal varies in level abruptly, the signal after the digital conversion does not have such a variation.

Description

[Detailed description of the invention] [Table of contents] Overview Industrial field of application Conventional technology Problems to be solved by the technology of the prior application (Figure 8.9) (Figures 10 to 13) Problems to be solved by the invention Means action embodiment (1) An embodiment of the first invention (Figs. 1 to 3) (2) First embodiment of the second invention (Figs. 4 to 6) (3) Example of the second invention Embodiment 2 (Fig. 7) Effects of the invention [Summary] Regarding the optical position detection device, firstly, the purpose is to improve measurement accuracy without sudden changes in signal strength, and secondly, the purpose is to improve measurement accuracy even when the amount of light is small. The first invention aims to improve the detection accuracy of optical position by increasing the S/N ratio, and in the first invention, incident light is photoelectrically converted, and the photocurrent to be shunted through a predetermined resistance layer is divided from a predetermined electrode. A light detection means for outputting light, a calculation means for calculating the sum and difference of each output signal taken out from the electrode, and a light detecting position of light incidence based on the ratio of the sum and difference calculated by the calculation means. In the optical position detecting device, the optical position detecting device includes a predetermined stage of amplifier for amplifying the sum and the difference with a predetermined gain on the output side of the calculating means, and a predetermined stage of amplifier for amplifying the sum with a predetermined gain. Selection means for selecting the amplifier that provides the optimum gain for the sum and difference based on the output, an A/D converter for A/D converting the output of each stage of the amplifier for the sum and difference, and the selection means switching means for switching the A/D converter to select the digital value of the optimal gain sum and difference signal based on the output of the optical position detecting means; The light incident position is configured to be detected based on the digital values of the sum and difference signals from the D converter.

In the second invention, in the optical position detection device,
The light is divided into a plurality of parts by changing the light intensity by a beam splitter, each of the divided lights is provided with the light detection means and the calculation means, and the sum and calculation are performed based on the sum signal of each output calculated by the calculation means. a selection means for selecting the arithmetic means that provides the optimum gain for the difference; and a selection means for selecting the arithmetic means that provides the optimum gain for the difference; The structure is such that the light incident position is detected based on the sum and difference signals switched by a switching means which A/D converts the acid phase and difference signals sometime later.

[Industrial application field]

The present invention relates to an optical position detection device, and more specifically to an optical position detection device (PSD: Po5ition 5ensi).
The present invention relates to improvements in signal processing circuits for tive detectors (hereinafter abbreviated as PSD).

A PSD is a device with a pin structure that utilizes the effect that photocurrent flowing through a semiconductor is shunted through a surface resistance layer. Electrical signal (X-
Y-coordinate signal) can be obtained, and the position resolution and responsiveness are excellent. Therefore, it is possible to apply it to automatic focusing devices such as cameras, various distance measuring devices, positioning devices, etc.

[Conventional technology]

FIG. 8 is a sectional view showing the structure of a one-dimensional PSD. In this figure, 1 is PSD, PSDl is a p-type resistance layer 2 on the surface of a flat silicon plate, an n° layer 3 on the back surface, and 1 in the middle.
-3i layer 4, output terminals 5, 6 are formed on both sides of p-type resistance layer 2, and common terminal 7 is formed on n' layer 3. It is assumed that a predetermined bias voltage is applied between the output terminal 5.6 and the common terminal 7, and a light spot is irradiated to the X point. The midpoint of the sample is taken as the origin of the coordinates, and the length of the sample is 2L.

When a light spot is incident on the PSDI, a charge proportional to the light energy is generated at the incident position, and the generated charge passes through the resistance layer (P layer in this case) as a photocurrent and is output from the electrode. The resistance layer is formed to have a uniform resistance value over the entire surface, and the photocurrent is divided and extracted in inverse proportion to the distance (resistance value) to the electrode. Here, if the distance between the electrodes is 2L and the photocurrent is Io, the currents I+ and It taken out from the output terminal 5.6 are expressed by the following formula (■), and the light position and light position are determined by the following formulas (■ and ■), respectively. shown.

Light intensity = r+-zz ・・・・・・■Figure 9 is PS
2 is a diagram showing a signal processing circuit for processing the output currents I, , I2 of Dl to obtain an optical position signal. FIG. In this figure, 11 is a signal processing circuit, and OP amplifiers 12 to 11 are signal processing circuits.
16, capacitor CCt, resistor Rf I, Rf z
, R+ = R7 and an analog divider 17. OP amplifier 12.13, capacitors C, , C, and resistors Rf, , Rf2 constitute a current-voltage conversion circuit 18, and OP amplifier 14 and resistors R+, Rz, R
s constitutes an adder circuit 19. Further, the OP amplifier 15 and resistors R1, R4, Rh, and R'r constitute a differential circuit 20, and the OP amplifier 16 and resistors R11 and R9 constitute an inverting circuit 21. Therefore, the conventional signal processing circuit 11 has two current outputs 1. , I2 is converted into voltage by the current-voltage conversion circuit 18, and the addition circuit 19
A sum and a difference are created by a differential circuit 20, and a position signal is obtained by an analog divider 17.

However, the above conventional device has the following problems.

■ The dynamic range of light intensity is small.

When the brightness of light itself changes, the ratio of the maximum value to the minimum value that can be handled is called the dynamic range, and this is approximately 10
It's double. As will be described later, this is a problem with the signal processing circuit rather than with the PSD itself.

■ The operating speed is slow, approximately IMHz.

■ Poor accuracy. In some cases, the error is 10% or more.

The reason for these shortcomings may be the PSD itself (the fact is that an analog division circuit (see analog divider 17 shown in FIG. 9) is used for division when extracting it as an optical position signal. Generally speaking, Although analog division circuits have slow operating speed, small dynamic range, and poor accuracy, they can easily perform division with a single IC (there is no other device that can perform division with a single IC), so they are suitable for PSD. Widely used.

In order to eliminate the above-mentioned problems, there is a system in which the sum and difference, which are analog signals, are converted into digital signals using an A/D converter and the digital division circuit is used to perform the conversion (Japanese Patent Application No. 61-301718). reference). However, in this case, the A/D converter becomes a bottleneck. The resolution of the A/D converter is high (the faster the speed, the higher the accuracy will be, but since the speed and resolution are in an inverse relationship with the A/D converter, the current resolution is 12 bits, for example).
The resolution limit is IMllz, 10 bits, and about 20 MHz. The problem in this case is the optical dynamic range, and even if digital division is used, a large dynamic range cannot be obtained. That is, when the denominator voltage becomes small, the number of effective bits of data after A/D conversion decreases, and the calculation accuracy deteriorates. for example,
Assuming that the denominator is 12 bits and a speed of IM Hz is required, even if you try to increase the highest precision, the limit will be 12 bits. 12 bit resolution and 12 molecules
For example, if the brightness changes by a factor of 10, the resolution will drop from a full 12 bits to the equivalent of 8 bft. Furthermore, if the size changes by 16 times, in the worst case, only 8 bits of accuracy can be obtained, and 12 bits of accuracy is obtained.
Even if t A/D converter is used, 8 bit/
With 8 btt, an accuracy of just under 8 bits can be obtained at most.

In this way, among the light positions expressed as numerator (difference)/denominator (sum), accuracy cannot be improved if the size of the denominator itself changes significantly.

PSD is used to find the position of light, but depending on the object, it may measure things whose brightness changes with the position, and since the denominator is proportional to the brightness (light power of the light), the amount of light changes as well. When the position also changes, there is a desire for something that can detect the position without depending on the amount of light.

In addition, in camera autofocus, etc., such M
Although accuracy on the order of 110 Hz is not required, current methods are insufficient when applied to very high precision and high performance measuring devices.

Therefore, in order to solve the above-mentioned problems, the applicant of the present invention has previously proposed an optical position detection device capable of detecting a highly accurate optical position signal at high speed and a wide dynamic range. It is shown as in Figure 13. The present invention relates to an improvement on the earlier application, and since there are some common circuits, the apparatus of the earlier application will be described in detail below.

Figure 10 shows an arithmetic circuit that calculates the sum and difference between the two output signals of the PSD, and has the same function as the conventional example shown in Figure 9, and the same components are designated by the same numbers. It is attached. In Fig. 10, 31 is an arithmetic circuit (arithmetic means)
, 32 is an A/D converter, and the arithmetic circuit 31 is ○P.
It is composed of amplifiers 33 to 36 and resistors R11 to R19. OP amplifier 33.34 and Ro, Rlg are P
SDI output current I+, current that converts 12 to voltage -
A voltage conversion circuit 37 is configured, an OP amplifier 35 and resistors R13 to RIS constitute an adder circuit 38, an OP amplifier 36 and resistors R1th to RI9 constitute a differential circuit 39, and the outputs of the adder circuit 38 and the differential circuit 39 are The sum (V+
+V! ) and is output as a difference (V+VZ) to the signal processing circuit 41 shown in FIG. In addition, in this example, in order to obtain the digitized light intensity signal, an A/D
The sum signal sent to the converter 32 is A/D converted.

In FIG. 11, 41 is a signal processing circuit, and the signal processing circuit 41 is constituted by each element described below. That is, the signal processing circuit 41 has N stages of amplifiers 42 to 45 that amplify the sum (original signal) inputted from the adder circuit 38 and the previous stage input signal with a gain A, and a difference (v+VZ).
is input to N-stage amplifiers 46 to 49 which amplify the difference (original signal) and the previous stage input signal with gain A, as well as the sum and each output of the amplifiers 42 to 45, similar to amplifiers 42 to 45. sum and each output at a predetermined slice level S
The comparators 50 to 54 to compare with L and each output 0 to N of the comparators 50 to 54 are input, and the highest input "L" among these 00 to N data inputs is detected and its value is converted into a 3-bit code. a demultiplexer 56 that redistributes the prioritized data of the priority encoder 55 into data 0 to N; Analog switches 57 to 61 are connected to each output side of difference and amplifiers 46 to 49, and are connected to analog switches 57 to 61 which turn on the optimum one by a selection signal from 56 and output it as a sum after level conversion, and are connected to each output side of difference amplifiers 46 to 49, Analog switches 62 to 66 that turn on the most suitable one and output it as the difference after level conversion.
It is composed of and.

Therefore, when N stages of amplifiers with a gain of A (for example, 4 stages of amplifiers with a gain of 10 times) are connected to the sum signal (denominator), the difference signal (numerator) also has the same gain of 10 as the sum signal.
Connect 4 stages of double amplifier and analog switch 57 to 66
By switching , a pair of amplifiers 42 to 49 having the same gain in the denominator and numerator are simultaneously selected.

The amplifiers 42 to 49 constitute an amplifier 67, the comparators 50 to 54, the priority encoder 55 and the demultiplexer 56 collectively constitute a selection circuit (selection means) 68, and the analog switches 57 to 66 constitute a switching means 69. ing.

The sum and difference after level conversion are respectively input to A/D converters 70 and 71 shown in FIG. It is output to the digital division circuit (optical position detection means) 72 as . The digital division circuit 72 divides the difference (numerator) by the sum (denominator) and outputs the result to the outside as a position (height) signal.

Next, the effect will be explained.

As shown in FIG. 13, the gain A of the amplifiers 42 to 49 is 10 times, the number of stages N of the amplifiers 42 to 49 is 4, the slice level SL is IV, and the saturation voltage of the amplifiers 42 to 49 is 15V, A The input voltage range of the /D converter 70 and 71 is ±IOV.

Now, assuming that there is an input signal of 5V as a sum signal (denominator voltage), the input signal of all comparators including the ×1 comparator (comparator 50) is the reference voltage (slice level 5L) in comparators 50 to 54.
Since it is larger than IV, all H'' is output to the priority encoder 55. Also, when the sum signal is 0.5V, only the comparator 50 is L'', and the remaining comparators 51 to
54 becomes "H", and when the sum signal is 0.5 V, comparators 50 and 51 become "L", and the remaining comparators 5
2 to 54 are "H" (see table).

(This page, blank space below) The comparison results of the comparators 50 to 54 are input to the priority encoder 55 with priorities, and as shown in the table, the predetermined priorities are 0.1.2...
. . ., the demultiplexer 56 turns on only the corresponding signal, and the denominator and numerator of the analog switches 57 to 66 simultaneously turn on the optimum one bare.

That is, the selection circuit 68 selects the pair of amplifiers 42 to 46 that have the optimum gain so that the value of the denominator voltage falls within a certain range.

Therefore, a signal with AI gain applied to both the denominator and numerator is A/D converted, and since the gains of the denominator and numerator are equal, the result of division is correct. Further, the dynamic range of the denominator (light intensity) is AN''' (104 in this embodiment), which is much larger than the conventional circuit shown in FIG.

As a result, a highly accurate optical position signal can be obtained for the PSD at high speed (IMHz) and wide duplex range (10').

In this example, the gain per stage is 10 times, but it can be set appropriately depending on the desired accuracy. For example, if you want 8-bit accuracy, the A/D converter is 12 bits and the IMHz speed is If desired, an amplifier with a gain of about 16 times (actually about 10 times taking margin into consideration) is selected.

[Problem to be solved by the invention]

By the way, in the device according to the prior application, the output signal of the amplifier with different gain is switched depending on the magnitude of the sum signal, so that the output signal of the amplifier with different gain is changed depending on the magnitude of the sum signal. When there is a sudden change, there is a problem in that an error occurs in the measured value due to the response characteristics of the amplifier or A/D converter, resulting in a decrease in accuracy.

This is especially true when the amplitude of the analog signal changes rapidly.
This is due to deterioration in conversion accuracy of A/D converters and the like.

Furthermore, the second problem is as follows.

That is, since it is necessary to prevent the sum voltage of the signals from being saturated when the amount of light is maximum, a small voltage signal must be amplified by an amplifier with a large gain when the amount of light is small. Therefore, when the amount of light is small, amplifier noise and external noise are included in the signal, resulting in a poor S/N ratio. the result,
There was a problem in that the error in the optical position signal became large.

Therefore, the present invention aims, first, to improve measurement accuracy without sudden changes in signal strength, and second, to improve optical position detection accuracy by increasing the S/N ratio even when the amount of light is small. The purpose is to

[Means to solve the problem]

In order to achieve the above object, the optical position detection device according to the first invention includes a photodetecting means for photoelectrically converting incident light and dividing and outputting a photocurrent to be shunted through a predetermined resistance layer from a predetermined electrode; A light position detection device comprising a calculation means for calculating the sum and difference of each output signal, and a light position detection means for detecting the incident position of light based on the ratio of the sum and difference calculated by the calculation means. In the apparatus, on the output side of the calculation means, there is provided a predetermined stage of amplifier for amplifying the sum and difference with a predetermined gain, and an amplifier that is optimal for the sum and difference based on the output of each stage of the amplifier that amplifies the sum. an A/D converter that A/D converts the sum and difference outputs of each stage of the amplifier; and an A/D converter that A/D converts the sum and difference outputs of each stage of the amplifiers; and switching means for switching the A/D converter to select the digital value of the sum and difference signal, and the optical position detecting means selects the sum and difference signals from the A/D converter switched by the switching means. The incident position of light is detected based on the digital value of .

Further, in the second invention, there is provided a photodetecting means for photoelectrically converting incident light and dividing and outputting a photocurrent that is shunted through a predetermined resistance layer from a predetermined electrode, and a sum of each output signal taken out from the electrode and a In an optical position detection device comprising a calculation means for calculating a difference, and a light position detection means for detecting the incident position of light based on the ratio of the sum and difference calculated by the calculation means, the light is transmitted to a beam splitter. The amount of light is changed by dividing the light into a plurality of light beams, each of the divided lights is provided with the light detection means and the calculation means, and the optimum sum and difference are determined based on the sum signal of each output calculated by the calculation means. a selection means for selecting the arithmetic means that provides a gain; and a selection means for switching the sum and difference signals of the respective outputs calculated by the arithmetic means based on the output of the selection means, and at least either before or after the switching. The sum and difference signals are A/
A switching means for D conversion is provided, and the optical position detection means includes:
The light incident position is configured to be detected based on the sum and difference signals switched by the switching means.

[Effect]

In the first invention, the output of each stage of the sum and difference amplifier is A
A/D converter performs A/D conversion, and then the A/D converter is switched by a switching means to select the digital value of the optimal gain sum and difference signal based on the output of the selection means, and the sum and difference signals are switched by the switching means. The incident position of the light is detected based on the digital value of the difference.

Therefore, there is no need to switch signals using an analog switch as in the past, the signal strength does not change suddenly, and measurement accuracy is improved.

Further, in the second aspect of the invention, the incident light is divided into a plurality of light beams by a beam splitter with different amounts of light, and each of the divided light beams is provided with a light detection means and a calculation means. The sum and difference signals of the respective outputs calculated by these calculation means are switched based on the output of the selection means, and are A/D converted either before or after the switching.
The light incident position is detected based on the sum and difference digital signals after conversion.

Therefore, the signal is already at the required level immediately after the photodetection means, and the influence of amplifier noise and external noise is eliminated.
/N ratio is improved, and detection accuracy is improved.

〔Example〕

Hereinafter, the present invention will be explained based on the drawings.

1 to 3 are diagrams showing an embodiment of the optical position detection device according to the first invention. The optical position detection device of this embodiment is
Although it has the configuration shown in FIG. 3, the same components as in the example of the prior application are given the same numbers and redundant explanation will be omitted.

First, Fig. 1 is a circuit diagram similar to that of the previous application, with two P
Convert the SDI output currents It and It into voltages, and calculate the difference (Vl
V2) and the sum (Vl +Vz), and these signals are sent to the signal processing circuit 81. In addition,
Similarly, the A/D converter 32 A/D converts the sum signal to obtain a digitized light intensity signal.

FIG. 2 shows the signal processing circuit 81. In this figure, the signal processing circuit 81 is an N-stage amplifier that amplifies the sum (Vl +V2) signal input from the adder circuit 38 and the input signal of the previous stage with a gain of A. 82-84, the difference (v+-V
2) N-stage amplifiers 85 to 87 to which a signal is input and which amplify the difference signal and the previous stage input signal with gain A in the same way as amplifiers 82 to 84;
- 84 are manually inputted, and comparators 81 - 91 which compare this sum (Vl + VZ) and each output with a predetermined slice level SL, and each output 0 - N of comparators 88 - 91 are inputted. A priority encoder 92 detects the most significant "L" among the data inputs and encodes the value into a 2-bit code;
+v2) and each output side of the amplifiers 82 to 84, and converts these analog signals into digital signals and outputs them as digital signals.
An A/D converter 97 is connected to the output sides of the D converters) 93 to 96, the difference (v+ -V, ) and the amplifiers 85 to 87, and similarly A/D converts and outputs each of these analog signals. ~100, and the most suitable one is selected based on the data from the prioritized priority encoder 92 connected to each output side of the A/D converters 93 to 96, and the level conversion and A/D converter are performed. The selector 101 outputs the digital sum after D conversion, and the optimum one is selected based on the data from the priority encoder 92 connected to each output side of the A/D converters 97 to 100, and level conversion and A/D conversion are performed. and a selector 102 that outputs a digital difference after /D conversion.

Therefore, when N stages of amplifiers with a gain of A (for example, 3 stages of amplifiers with a gain of 10 times) are connected to the sum signal (denominator), the difference signal (numerator) also has the same gain of 10 as the sum signal.
Three stages of double amplifiers are connected, and the outputs of each stage of the sum and difference signals are A/D-converted to the selector 101.
By selectively switching through 102, a pair of amplifiers 82 to 87 having the same denominator and numerator gains are simultaneously selected and output as sum and difference digital values.

The amplifiers 82 to 87 constitute an amplifier 103, and the comparators 88 to 91 and the priority encoder 92
constitutes selection means 104 as a whole, and selectors 101 and 102 constitute switching means 105.

The sum and difference digital signals selected by the selectors 101 and 102 are input to a digital division circuit (optical position detection means) 1o6 as shown in FIG. 3, and the division circuit 106 sums the difference (numerator). Divide by (denominator),
Output to the outside as a position signal.

In the above configuration, in this embodiment as well, the selection means 104 simultaneously selects one optimal denominator and numerator in pairs, as in the prior application example, but at this selection stage, each of the sum and difference signals has already been selected. The output of the stage is A/D converted and becomes a digital signal. Therefore, unlike the prior application, there is no need to use an analog switch to switch between signals with different gains, so even if the magnitude of the analog signal suddenly changes, there will be no such change in the signal after digital conversion. . As a result, measurement errors do not occur due to the response characteristics of the amplifiers 82 to 87 and the A/D converters 93 to 100, and the accuracy of optical position detection can be significantly improved.

Next, FIGS. 4 to 6 are diagrams showing a first embodiment of the optical position detection device according to the second invention. FIG. 4 is a diagram showing the configuration of the optical system, and in this diagram, incident light 110 is transmitted to lens 1.
After passing through the beam splitter 11, N stages (three stages in this embodiment) of beam splitters 112 to 114 divide the beam into B:B2:B''.
...The light is divided into multiple parts by changing the amount of light in equal proportions and in a power order. In this example, 90%, 9%, 0.9%
, 0.1%, and these divided incident lights 110 are transmitted to four PSDs (photodetection means) 121.
I received it at ~124.

Each of the PSDs 121 to 124 is connected to a separate arithmetic circuit. For example, the PSD 121 is connected to an arithmetic circuit 131 as shown in FIG. 5, and the arithmetic circuit 131 outputs sum and difference signals. Since the contents of the arithmetic circuit 131 are the same as those shown in FIG. 1 described above, the same numbers are given. Therefore, the same number of arithmetic circuits as the plurality of PSDs are provided, and the sum and difference signals output from each of these arithmetic circuits are processed by the signal processing circuit 14 shown in FIG.
Output to 1. Note that the outputs of each arithmetic circuit are illustrated as the difference, sum, etc. of the PSD 121 for convenience of explanation.

The signal processing circuit 141 is shown in FIG.
Since the others are the same except that 2 to 87 are removed, the same numbers are given. Therefore, the signal processing circuit 141
selects and switches the output from the arithmetic circuit that gives the optimum gain for the sum and difference based on the sum signal of each output calculated by each arithmetic circuit, and before this selection, the sum and difference signals are /D conversion processing. Signal processing circuit 1
The outputs from 41, that is, the sum and difference digital signals, are input to the digital division circuit 72 similar to that shown in FIG. 3 and processed therein, and therefore will not be described here.

In the above configuration, first, the arithmetic circuit 131 in FIG. 5 adjusts the signal level to a required level. Specifically, the sensitivity of the voltage/light amount is set by each resistance value of the circuit, and in particular, the resistance RI l + RI 2 determines the coefficient of current-voltage conversion, and for example, there is a relationship such as v, = engineering, XRII . Therefore, the incident light 110 is 90%, 9%,
Divided into 0.9%, 0.1%, each PSD1
When the incident light 110 is dark, the PSI 121 is selected, and when the incident light 110 is bright, the PSD 124 is selected. Therefore, for example, if the signal intensity fluctuation is 104 times the light amount range and the saturation voltage of the circuit is IOV, the lowest signal immediately after passing through the PSD is 1 mV. On the other hand, in this example, the optimal rangein PSD
is selected, the output level of the arithmetic circuit is approximately 1.
~10V is switched by the signal processing circuit 141 and output. In this way, in this embodiment, PSD1
Since the signal is set at the required level immediately after 21 to 124, even when the amount of light is small, the influence of amplifier noise and external noise can be appropriately eliminated and the S/N ratio can be improved. Position detection accuracy can be improved.

FIG. 7 is a diagram showing a second embodiment of the optical position detection device according to the second invention. This embodiment differs from the first embodiment in which the output of each PSD is first A/D-converted, but the most suitable PSD out of a plurality of PSDs is determined and then A/D-converted. That is, in FIG. 7, five PSDs (121 to 125) are provided, and the sum and difference of their outputs are respectively input to the signal processing circuit 151. The signal processing circuit 151 is the same as that shown in FIG. 11 of the prior application example, except that the bearings 42 to 49 are removed. Therefore, the signal processing circuit 151
The optimum one is selected from among the sum and difference signals from 21 to 125 and output. Thereafter, the light position is detected by A/D conversion using a circuit having a configuration similar to that shown in FIG. Therefore, although the processing position of the A/D conversion of the signal is different in this embodiment, the same effects as in the first embodiment can be obtained.

Note that the embodiment of the second invention is not limited to the above-mentioned embodiments; for example, a configuration may be adopted in which a plurality of PSDs are used and a plurality of amplifiers with different gains are connected to each output of the PSDs. .

〔Effect of the invention〕

According to the first aspect of the invention, it is possible to prevent the signal strength from changing rapidly, and it is possible to improve the detection accuracy of the optical position.

Further, according to the second invention, even when the amount of light is small, the S/
The N ratio can be increased, and the detection accuracy of the optical position can be improved.

[Brief explanation of drawings]

1 to 3 are diagrams showing an embodiment of the optical position detection device according to the first invention, FIG. 1 is a circuit diagram of its arithmetic circuit, FIG. 2 is a configuration diagram of its signal processing circuit, and FIG. 3 is a block diagram of the division circuit, FIGS. 4 to 6 are diagrams showing the first embodiment of the optical position detection device according to the second invention, FIG. 4 is a configuration diagram of the optical system, and FIG. 6 is a configuration diagram of the signal processing circuit; FIG. 7 is a configuration diagram of the signal processing circuit showing a second embodiment of the optical position detection device according to the second invention; Figure 8.9 is a diagram showing a conventional optical position detection device, Figure 8 is a sectional view showing the structure of its PSD, Figure 9 is a circuit diagram of a signal processing circuit, and Figures 10 to 13 are prior patent applications. FIG. 10 is a circuit diagram of its arithmetic circuit, FIG. 11 is a block diagram of its signal processing circuit, FIG. 12 is a block diagram of its division circuit, and FIG. FIG. 7 is a diagram showing the relationship between the original signal of the sum signal and the selected output. 1.121-124...PSD (light detection means), 31.131... Arithmetic circuit (arithmetic means),
32.93~100...A/D converter (A
/D converter), 81.141, 151...signal processing circuit, 8
2-87...Amplifier, 88-91...Comparator, 92...
・Priority encoder, 101.102...
... Selector, 103 ... Amplifier, 104 ... Selection means, 105 ... Switching means, 106 ... Digital division circuit (light position detection means) 110 ......Incoming light, 111...Lens, 112-114...-Beam splitter. No.! FIG.
3 Figure Ill: Lenses 112 to 114: Beam splitters 121 to 124: PSD Figure 4 is a configuration diagram of the optical system of the first embodiment of the second invention.

Claims (2)

[Claims] (1) Photodetection means that photoelectrically converts incident light and divides and outputs a photocurrent that is shunted through a predetermined resistance layer from a predetermined electrode, and a calculation that calculates the sum and difference of each output signal taken out from the electrode. and an optical device detecting means for detecting a light incident position based on a ratio of the sum and difference calculated by the calculating means, wherein the sum and the difference are arranged on the output side of the calculating means. a selection means for selecting an amplifier in a predetermined stage that amplifies the difference with a predetermined gain; and an amplifier that provides an optimum gain for the sum and the difference based on the output of each stage of the amplifier that amplifies the sum; An A/D converter for A/D converting the sum and difference outputs of each stage of the amplifier; switching means for switching the D converter, and the optical device detection means detects the incident position of light based on the digital values of the sum and difference signals from the A/D converter switched by the switching means. An optical device detection device characterized in that it is configured as follows. (2) Photodetection means that photoelectrically converts incident light and divides and outputs a photocurrent that is shunted through a predetermined resistance layer from a predetermined electrode, and a calculation that calculates the sum and difference of each output signal taken out from the electrode. and an optical device detecting means for detecting the incident position of light based on the ratio of the sum and the difference calculated by the calculating means, wherein the light is divided into a plurality of light beams by changing the amount of light using a beam splitter. The light detecting means and the calculating means are provided for each divided light, and the calculating means that gives the optimum gain to the sum and the difference is selected based on the sum signal of each output calculated by the calculating means. a selection means for switching the sum and difference signals of the respective outputs calculated by the calculation means based on the output of the selection means, and at least either before or after the switching, the sum and difference signals are A/ A switching means for performing D conversion, and the optical position detection means is configured to detect the incident position of light based on the sum and difference signals switched by the switching means. .