JPS6319884A - Light position detecting device - Google Patents

Abstract

PURPOSE:To correctly detect a light position by a method wherein light position signals to indicate the position in the X direction and light position signals to indicate the position in the Y direction are so contrived as not to interfere with each other, and at the same time, the amount of light is controlled in such a way that the sum total of the light position signals in the X direction or the Y direction becomes constant. CONSTITUTION:Photocurrents IX+, IX-, IY+ and IY- which are outputted from each electrode 9-1, 9-2, 3-1 and 3-2 of a light position detecting element 1 are each converted into voltages V1-V4 by operational amplifiers 11a-11d for current-voltage conversion corresponding to the electrodes. The output voltage V1 of the operational amplifier 11a and the output voltage V2 of the operational amplifier 11b are inputted to a light source driving circuit 20 and these voltages V1 and V2 are added to the inversion input terminals of an operational amplifier 22 of the driving circuit 20 and added. Driving current ID which is outputted from the output terminal by this operational amplifier 22 is controlled so as to prevent the fluctuation at the time the sum of the voltages V1 and V2 fluctuates, that is, at the time the sum of the photocurrent IX+ and the photocurrent IX- fluctuates.

Description

Detailed Description of the Invention A. Industrial Field of Application The present invention has an optical position detection element that outputs an optical position signal, that is, a photocurrent, according to the position of incident light, and is used as a position sensor, an acceleration sensor, etc. The present invention relates to an optical position detection device.

B. Prior art The optical position detection element used in this type of optical position detection device is as follows:
For example, they are supplied as shown in FIGS. 6 and 7. That is, the optical position detection element includes a glass substrate 41, a low resistance electrode film (back electrode) 42, an n-type amorphous silicon film 43, an intrinsic amorphous silicon film 44, a p-type amorphous silicon film 45, and a light-transmitting High resistance film 46
and.

It consists of low resistance metal electrodes (counter electrodes) 47a and 47b.

Now, a voltage is applied so that the electrode 42 is positive and the electrodes 47a and 47b are negative, and a light beam A having an area sufficiently smaller than the area of the optical position detection element is applied to the high resistance film 46 from the high resistance film 46 side.
6, the lower layer film 43 of the high resistance film 46
Since 45 supplies a photodiode, only the area irradiated with the light beam A receives an optical position signal, that is, photoelectric construction. flows. This photocurrent I0 passes through the amorphous silicon films 43, 44 and 45 from the electrode 42, is divided by the high resistance film 46, and is distributed to each electrode 47a as currents IA and IB.
and 47b, respectively. Here, the high resistance film 4
6 is formed uniformly, the distances XA and X days from the irradiation position B of the light beam A to the electrodes 47a and 47b are proportional to the resistance values RA and RB therebetween.
The distance between the currents IA and IB and the distance #XAJXs can be determined as follows.

A two-dimensional optical position detecting element 10 as shown in FIG. 8 is based on the principle of the one-dimensional optical position detecting element shown in FIGS. 6 and 7.
You can get 0. This two-dimensional optical position detection element 10
0 is four opposing electrodes 101-1, 10 for detecting two-dimensional positions (X direction, Y direction), respectively arranged on one surface.
1-2, 101-3, 1ot-4 (total bending electrode 4 in Fig. 6)
7a, 47b). This optical position detection element 100 is connected to an optical position detection circuit 50 as shown in FIG. Here, the four optical position detection elements 100, the detection circuit 50, the light source 60, and the driving circuit 70 provide an optical position detection device.

In FIG. 9, a DC power supply 103 is connected to the back electrode 102 (corresponding to the electrode 42 in FIG. 6), and a reverse bias voltage is directly applied to the optical position detection element 100 by the power supply 103, thereby causing the When light enters a certain position of the position detection element 100, the four opposing electrodes 101-1, 10
1-2, 101-3, and 101-4, photocurrents I x+, I The optical position detection circuit 50 determines the X-direction and Y-direction coordinates X o and Y o of the light irradiation position of the optical position detection elements too and h based on this light '7rL flow Ix0 to Iy-.

That is, the photocurrents I x+, I x-, I Y+, I
Y- are operational amplifiers 51-1, 51-2,
51-3 and 51-4 perform current-voltage conversion into voltage values v, v2', v3, and v4 corresponding to the photocurrent values. Those voltages V, ~■4 are operational amplifier 72
The sum of the voltages V and -V4 input to the 0 inverting input terminal is calculated, and the operational amplifier 72 outputs a drive current ID so that the sum is always constant. That is, the smaller the sum, the larger the drive current ID, and the larger the sum, the smaller the drive current Io.

Then, the operational amplifier 52-1 subtracts the output voltage v1 and ■2 and outputs V, -V2, whereby the position XO of the light incident on the optical position detection element 100 in the X direction becomes X o = α (II I2) ...(
2). Here α is a proportionality constant.

Furthermore, the operational amplifier 52-2 subtracts the output voltages ■3 and ■4 and outputs V3-v4, whereby the position Y0 of the light incident on the optical position detection element 100 in the Y direction is determined as Yo=α(I3 -In) ... can be found as (3). In addition, in this specification, photoelectric construction 1 to
(14) and the voltage values VI to (4) related thereto are respectively referred to as optical position signals.

C9 Problems to be Solved by the Invention However, this conventional two-dimensional optical position detection element
As shown in the figure, the current Ix+ in the X direction.

Electrodes 101-1, 101-2 for detecting Ix- and electrodes 101-3, 1 for detecting Y-direction currents IY+, IY-
01-4 are on the same plane, both the position coordinates X and Y of the light spot affect, for example, the photocurrent Ix-. That is, each photocurrent I x+, I x-, I Y+
.

IY- is published by the Institute of Electrical Communication Engineers, Technical Research Report No. 159 (1
984), pages 95-102,
Letting Is be the sum of photocurrents I x+, I x-, I Y+, and I Y-, then 5 inh [(2n-1) π] (4) where x and y are the coordinates of the light spot.

L is expressed as the distance between electrodes. Therefore, when the optical spot on the optical position detection element is scanned in a grid pattern as shown in FIG. 10 and the optical position is detected based on the above-mentioned equation (4) using the circuit shown in FIG. The optical position detection characteristics shown in FIG. 11 are distorted. In other words, the two-dimensional optical position detection element has one side.
When using an IT pole type, there is a problem that the optical position cannot be detected accurately due to the nonlinear relationship between the leading δ and the detected photocurrent due to the single-sided electrode arrangement. there were.

An object of the present invention is to provide an optical position signal representing the position in the X direction and a
Optical position detection that solves the above-mentioned problems by preventing the optical position signals representing the position in the directions from interfering with each other and controlling the amount of light so that the sum of the optical position signals in the X or Y direction is constant. The goal is to provide equipment.

Means for Solving the D0 Problem The present invention includes a light source, a drive circuit that supplies a drive current to the light source, and a light beam emitted from the light source that outputs two or more light position signals corresponding to the irradiation position. In an optical position detection device including an optical position detection element that outputs output from a terminal, the output terminal of the optical position detection element has a pair of X-direction position detection output terminals facing each other on a first surface, and a first and a pair of Y-direction position detection output terminals facing each other on a second surface different from the second surface, and the light source drive circuit is supplied from the X-direction or Y-direction position detection output terminal The drive current is supplied to control the drive current so that the total sum of the device signals is always constant.

When the light source emits light due to the 80 action drive current, a light beam is emitted toward the optical position detection element. The optical position detection element outputs optical position signals in the X direction and the Y direction from each output terminal at a ratio according to the position of the incident light.

In this case, since the output terminals for position detection in the X direction and the Y direction are on different planes, interference between device signals supplied from each output terminal is prevented. The device signals supplied from the X-direction or Y-direction position detection output terminals are summed in the drive circuit, output as a drive current, and supplied to the light source. The drive current is controlled so that the sum of the optical position signals in the X direction or the Y direction always becomes a certain constant value. Furthermore, at least the incident position of the light beam is calculated based on the optical position signals from each output terminal of the optical position detection element.

When using the optical position detection device as an acceleration sensor,
Acceleration is determined based on the sequentially calculated incident positions of the light beams.

F. Example Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4.

The optical position detection element 1 of this embodiment device is of a double-sided electrode type as shown in FIG. 1, and different pairs of electrodes are provided on different planes. That is, on the upper surface of a semiconductor (not shown) having a photosensor function, there are a pair of X-direction position detection output terminals (hereinafter referred to as electrodes) 9-1 and 9 for detecting X-direction currents Ix+ and Ix-, respectively. -2 are arranged facing each other, and the lower surface has a current Iy+ in the Y direction.
.

A pair of Y-direction position detection output terminals (hereinafter referred to as electrodes) 3-1 and 3'-2 for detecting IY-, respectively, are arranged opposite to each other and in the W-intersecting direction with electrodes 9-1 and 9-2. has been done.

As shown in FIGS. 2 and 3, the optical alignment detection element 1 includes a glass substrate 2 and a low-resistance lower electrode 3-1, 3-2 made of a gold-chromium alloy (Au-Cr alloy). and a lower divided resistor 1514 made of indium tin (ITO).
And n5 made of n-type amorphous silicon! A semiconductor film 5, an intrinsic semiconductor film 6 made of intrinsic amorphous silicon, an upper divided resistance film 8 made of fa-fa indium tin (ITO), and a low-resistance upper electrode 9 made of gold-chromium alloy (Au-Cr alloy). -1,9-2 are sequentially stacked and supplied. Here, the n-type semiconductor 1815 and the intrinsic semiconductor film 6 form a diode structure of the I-/toky barrier type. Further, the lower electrodes 3-1, 3-2 are for detecting the position of the light beam in the Y direction, and the upper electrodes 9-1 and 9-2 are for detecting the position of the light beam in the X direction. .

In this optical position detection element l, the upper electrode 9-1.9-
A voltage is applied to the lower electrode 3-1, 3-2 so as to be positive with respect to 2, and a light beam having an area sufficiently smaller than the area of the optical position detection element l is transmitted from the upper divided resistive film 8 side to the upper divided resistive film. When the position (Xo, Yo) on 8 is irradiated, electron-hole pairs are formed in the intrinsic semiconductor F16 at the irradiated position, and ? The ft electrons flow to the lower divided resistive film 4 via the n-type semiconductor FI5, and the holes move to the upper divided resistive film 8, and the photoelectric process 0 flows. This photocurrent I0 is divided by the lower divided resistive film 4 and similarly divided by the upper divided resistive film 8, and optical position signals are sent from the lower electrode 3-1 and the upper electrode 9-1 in the Y direction and the X direction, respectively. (Photocurrent)! ! +, Ix+ are output, and optical position signals (photocurrent) Iy- in the X and Y directions are output from the lower electrode 3-2 and the upper electrode 9-2, respectively.

Ix- is output.

Further, FIG. 4 shows the optical position detection circuit 10 and the light source drive circuit 20 of this embodiment device. In FIG. 4, the electrodes 9-1 and 9-2 in the X direction of the optical position detection element The electrodes 3-1 and 3-2 in the Y direction are connected to operational amplifiers lla and llb for current-voltage conversion.
c and lld, respectively. operational amplifier ll
The output terminals of b and lid are respectively connected to non-inverting input terminals of operational amplifiers 13a and 13b via a resistor 12a having a resistance value of 2R1. Also operational amplifier lla.

Each output terminal of 11c is connected to a resistor 12b with a resistance value R1.
It is connected to the inverting input terminals of operational amplifiers 13a and 13b via. The inverting input terminals of the operational amplifiers 13a and 13b are also connected. 1 is connected via a resistor 12b to variable resistors 14a and 14b to which a predetermined power supply voltage +Vcc is supplied.
The potential of the inverting input terminal can be adjusted to zero. The operational amplifiers 13a and 13b are subtracters that calculate the difference between the voltage applied to the non-inverting input terminal and the voltage applied to the inverting input terminal.
, Ix- is determined, and the operational amplifier 13b determines the difference G between the photoelectric currents iIy♦ and Imer in the Y direction.

The photocurrents Ix◆, Ix− in the X direction are expressed as voltages v, , v, respectively.
The output terminals of the operational amplifiers Lla and llb that convert into
It is also connected to the inverting input terminal of the operational amplifier 22 of the drive circuit 20 via resistors 21a and 21b. As a result, the photocurrents Ix◆, I
The voltages V1 and V2 corresponding to x- are added together.

The operational amplifier 22 is arranged so that the light source 2
The output terminal of the operational amplifier 22 is connected to the light source 25 via the resistor 23, and the light amount of the light source 25 is controlled by the drive current Io compensated by the operational amplifier 22.

In the optical position detection device supplied in this way, the driving current 0 of the light source 25 is controlled in a first-order manner, and the optical position on the optical position detection element 1 is detected.

Each electrode 9-1, 9-2 of the optical position detection element l.

3-1. Photoelectric fQIx◆ output from 3-2.

Ix-, Ima♦, and IY- are converted into voltages vI + v2 * v3 + v4 by corresponding operational amplifiers lla, 11b, llc, and lld for current-voltage conversion, respectively.

These voltages vI to v4 are input to the non-inverting input terminal 1 of the operational amplifiers 13a and 13b as subtracters, respectively, and are outputted from the output terminals of the operational amplifiers 13a and 13b as me=β(Ix+-Ix-).・(5) Ma=β(I y+ −I y−) ・・・(6
) optical position signals Gx, Gy are output. Here X +
> is the position coordinate of the light beam, β is the operational amplifier ll
a, llb, llc, 1id (7) are appropriate constants determined during current-voltage conversion.

Further, the output V1 of the operational amplifier 11a and the output voltage ■2 of the operational amplifier llb are input to the drive circuit 20 in FIG. It is added to and added to.

A drive current I is output by this operational amplifier 22 from its output terminal.

When the sum of the voltages vL and V2 changes, that is, the photocurrent Ix+ and the photocurrent 1. When the sum with x- fluctuates, it is controlled to prevent that fluctuation. Therefore, when the photocurrents Ix+ and Ix- decrease and their sum becomes smaller, the drive current In is increased to increase the amount of light from the light source 25, and when the photocurrents Ix+ and Ix- increase and their sum becomes larger, the drive current Io The amount of light from the light source 25 is reduced by decreasing the photocurrent Ix+.

The increase in Ix- is compensated for. Thereby, the sum of photocurrents Ix+ and Ix- is controlled to always be constant.

As described above, in this embodiment, by using the double-sided electrode type optical position detection element 1, the X-direction currents Ix+, I
Since interference between x- and Y-direction I Y+, I Y- is prevented, the drive circuit 20 reduces
It is only necessary to control the light intensity of the light source 25 so that the sum of either the Ix- or Y-direction photocurrents I y+ and I y- is constant, and in this case, the sum of the other photocurrents is also the same as that of one light. It becomes constant due to optical control using electric current.

An example of an acceleration sensor supplied using the above-mentioned position detection device will be explained with reference to FIG. 5.

This acceleration sensor includes a case 91, a light source 92 such as a light emitting diode (LED) provided on the top plate 91a of the case 91, a light guide 93 that guides light emitted from the light source 92 to the vicinity of the bottom plate 91b, and a light guide 93 that guides the light emitted from the light source 92 to the vicinity of the bottom plate 91b. The above-mentioned supplied optical position detection element 94 is arranged on the bottom plate 91b of the light guide 93 and obtains an optical position signal according to the position of the light beam emitted from the light guide 93, and the weight 95 is attached to the free end of the light guide 93. , and a viscous liquid 96 such as silicone oil filled in the case 91 to damp vibrations of the light guide 93. 97 is a lead connected to the drive circuit 20 and supplies the drive current ID to the light source 92; 98 is the electrode in the X direction and the Y direction of the optical position detection element 94; 9-1, 9-
2.

3-1. A lead 99 leads the output from 3-2 to the optical position detection circuit 10, and is a sealing gasket.

An acceleration calculation circuit 90 follows the optical position detection circuit 10.

In an acceleration sensor composed of such elements, the light $j92 guided into the light guide 93 is transmitted as a light beam from the tip of the light guide 93 to the optical position detection element 94.
It is emitted towards. The optical position detection element 94 is
Photocurrent Ix÷,I according to the position of the irradiated light beam
X-, I Y♦, and I y- are output from the lead 98.

Upon receiving this signal, the optical position detection circuit 10 performs the above-mentioned (5)
, (6) are output, and an acceleration calculation circuit 90 calculates the acceleration. For example, if acceleration acts to the right in the figure and the weight 95 at the tip of the light guide 93 displaces to the left, the output of the optical position detection element 94 changes in accordance with the displacement, and the output of the optical position detection element 94 changes based on the change in output. is detected. Note that the present invention can also be applied to a position sensor in which, for example, a light source is attached to a movable member and an optical position detection element is attached to a stationary member.

G9 Effects of the Invention According to the present invention, by arranging each pair of output terminals for optical position detection in the X direction and the Y direction on different planes, interference between charging currents can be effectively prevented, and either Since the driving current of the light source is controlled so that the sum of the optical position signals from one pair of output terminals is always constant, the optical spot on the optical position detection element can be scanned in a grid pattern. The signal becomes approximately grid-like and is not distorted like in the past.
Optical position detection accuracy is improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of a double-sided electrode type two-dimensional optical position detecting element, FIGS. 2 and 3 are cross sections of the double-sided electrode type two-dimensional optical position detecting element, and FIG. )H-II
3 is a cross-sectional view of FIG. 2 (7) III-mlf, FIG. 4 is a circuit diagram showing an optical position detection circuit and a light source drive circuit for a double-sided electrode type two-dimensional optical position detection element, and FIG. The figure is a cross-sectional view of an example of an acceleration sensor to which this embodiment is applied, FIG. 6 is a cross-sectional view showing a conventional single-sided electrode type optical position detection element, FIG. 7 is a plan view of FIG. 6, and FIG. 9 is a schematic perspective view of a single-sided electrode type element, FIG. 9 is a circuit diagram showing an example of an optical position detection circuit and a light source driving circuit of a conventional single-sided electrode type element, and FIG. 10 is a diagram showing an example of scanning a light beam in a grid pattern. , FIG. 11 is a characteristic curve diagram showing the case where the optical position is detected by the circuit of FIG. 9 when scanning is performed as shown in FIG. 10. 1: Optical position detection element 3-1.3-2: Y-direction electrode G-1, 9-2: X-direction electrode 10: Optical position detection circuit 20: Light source drive circuit 25: Light source patent applicant Nissan Motor Co., Ltd. Company Representative Patent Attorney Fuyuki Nagai Figure 1 ↓ 2.5 (V) Figure 2 n Figure 9

Claims (1)

[Scope of Claims] A light source, a drive circuit that supplies a drive current to the light source, and a light position detection device that outputs a light position signal corresponding to the irradiation position from two or more output terminals when a light beam is irradiated from the light source. In the optical position detection device, the output terminal includes a pair of X elements facing each other on the first surface.
and a pair of output terminals for position detection in the Y direction that face each other on a second surface different from the first surface; An optical position detection device characterized by taking the sum of optical position signals supplied from output terminals for position detection in the direction or the Y direction and controlling a drive current so that the sum is always constant.