JPH04363608A - Two-dimensional light position detector - Google Patents

Abstract

PURPOSE:To obtain a two-dimensional light position detector which enables a position detection accuracy for a light incidence position to be improved. CONSTITUTION:In a two-dimensional light position detector, at least one transparent resistance layer 3 is provided on upper and lower surfaces of a photovoltaic layer 4 and detection electrodes 2a-2d are provided at each resistance layer 3. Each resistance layer 3 is constituted by a number of face-shaped resistances 32 and a thin-wire-shaped resistance 31 connecting between the face-shaped resistances and at least face-shaped resistances are equal at upper and lower portions, thus enabling a position detection accuracy for light incidence position to be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-dimensional optical position detector for detecting the incident position of light.

0002

[Prior Art] Nowadays, in order to detect the linear displacement of an object with high durability and reliability, position sensors using variable resistors that use electrical contact are replaced by position sensors that emit radiation from a moving object or are reflected or transmitted by the moving object. A non-contact position sensor is used in which the displacement of the moving object is detected in a non-contact manner based on the position of the light received by the optical position detector. Unexamined Japanese patent publication 1986
JP-A-271413 and JP-A-63-32305 have proposed optical position detectors using an amorphous silicon semiconductor film. Such a conventional example will be explained below with reference to the drawings.

FIG. 6(a) shows a schematic configuration of a conventional optical position detector using an amorphous silicon semiconductor.
b) shows its cross section along the line O-O', and FIG. 7 shows a position sensor using a conventional optical position detector. The conventional device will be described below with reference to FIGS. 6 and 7.

In FIG. 6, A is a two-dimensional optical position detector, 1 is a substrate, which is transparent glass here, and 3 is a transparent resistance layer on the substrate 1 made of indium tin oxide (
An ITO film or a tin oxide (SnO2) film is formed by sputtering or vapor deposition. Reference numeral 4 denotes an amorphous silicon semiconductor (hereinafter referred to as a-Si) photovoltaic layer, which is formed into a P layer, an I layer, and an N layer in this order on the transparent resistance layer 3 by a vapor deposition method such as a plasma CVD method to form a PIN structure. A photovoltaic layer is formed. 3 is a transparent resistance layer provided on the a-Si electromotive force layer 4, which is an indium tin oxide (ITO) film or a tin oxide (SnO2) film.
Formed on the detection area of the Si photovoltaic layer 4 by sputtering or vapor deposition, 2a, 2b, 2c, 2d are detection electrodes,
The detection electrodes 2a and 2b are conductive layers formed on one transparent resistance layer 3 and the detection electrodes 2c and 2d are formed on the other transparent resistance layer 3 by vapor deposition of a metal such as Al.

Next, in FIG. 7, 7 is a light source such as an LED, and a visible light source is usually used due to the light receiving sensitivity characteristics of the a-Si photovoltaic layer 4, and 8 is a hole 81 through which light is transmitted. This is a two-dimensional moving plate having a two-dimensional moving plate, which is disposed between the light source 7 and the optical position detector A, and moves two-dimensionally over the optical position detector A. Further, 6 is a position detection circuit, and an optical position detector A
The detection electrodes 2a, 2b, 2c, 2d are connected to each non-inverting amplifier 6.
Connected to the inverting inputs of 1a, 61b, 61c, 61d,
The output of the non-inverting amplifier 62b is outputted to the outside as a position output Vy, while both the outputs of the non-inverting amplifiers 61a and 61b are connected to the inverting input of the non-inverting amplifier 63. The output of the comparison amplifier 63 is connected to one input of the comparison amplifier 64, the reference voltage Vref is connected to the other input of the comparison amplifier 64, and the output of the comparison amplifier 64 is connected to the light source 7. Ru.

Next, the operation of this conventional example will be explained. The light source 7 is driven by the comparator amplifier 64 to emit light, and a portion of this light beam passes through the hole 81 of the two-dimensional moving plate 8 and enters the optical position detector A. The incident light of the optical position detector A passes through the substrate 1 and one transparent resistance layer 3 and reaches the a-Si photovoltaic layer 4, and this incident light flux generates a photovoltaic force.
A photocurrent I is generated depending on the amount of incident light. This photocurrent I is shunted to the detection electrodes 2a and 2b provided with the transparent resistance layer 3 at both ends, and is also divided into the detection electrodes 2a and 2b provided with the transparent resistance layer 3 at both ends.
The flow is divided from c and 2d. At this time, each shunt photocurrent Ia, I
b , Ic , Id , detection electrodes 2a, 2b and 2c,
The length between 2d (light receiving length) is LX,LY, and the total resistance value Rtx,R of one transparent resistance layer 3 and the other transparent resistance layer 3
ty, the distances from the detection electrodes 2b and 2d to the light incident position are x and y, respectively, the resistance value Rx of the transparent resistance layer 3 between them, and the resistance value Ry of the transparent resistance layer 3. For example, focusing only on the X coordinate, , the position x is given by the following equation 1.

[0007]

[Math 1]

The photocurrents Ia and Ib are converted into voltages by a load resistor R in non-inverting amplifiers 61a and 61b, respectively, and become voltages Va and Vb, respectively, and the voltages Va and Vb are added by a non-inverting amplifier 63, Added value (Va + Vb)
comparison amplifier 64 so that Vref becomes a predetermined reference voltage Vref.
The amount of light emitted from the light source 7 is controlled.

On the other hand, the output of the non-inverting amplifier 61a is given a predetermined gain K by the non-inverting amplifier 62a, and the voltage Vx
is output as That is, the voltage Vx becomes the following equation 2, and the following equation 3 is obtained from the following equation 2.

0010

[Math 2]

[0011]

[Math 3]

The voltage Vx corresponds to the incident position of the optical position detector A in the X direction of the X-Y coordinates. Similarly, the voltage Vy corresponds to the incident position of the optical position detector A in the Y direction of the X-Y coordinates. Therefore, the position of the hole 81 of the two-dimensional moving plate 8 can be known by moving the two-dimensional moving plate 8 and detecting the incident position of the light transmitted through the hole 81 to the position detector A. Note that both of the resistance layers do not need to be transparent, and only the resistance layer serving as the incident surface may be made transparent.

[0013]

However, the conventional two-dimensional optical position detector has the following problems. That is, in addition to the photocurrent I, the transparent resistance layer 3 receives input offset voltages ΔVa and ΔV of the non-inverting amplifiers 61a and 61b.
The error current ΔI due to the difference in b is given by the following equation (4).

[0014]

[Math 4]

Since this error current ΔI flows, the current Ia actually flows through the load resistance of the non-inverting amplifiers 61a and 61b.
, Ib are, for example, (Ia + ΔI) and (Ib - ΔI), respectively, depending on the polarity and magnitude of the input offset voltage, and the position output Vx is expressed by the following equation 5, and the error current ΔI and the position error Δx due to the offset voltage are arise.

[0016]

[Math 5]

However, since the resistance value Rtx of the transparent resistance layer 3 in the X-coordinate direction of the conventional optical position detector A is small, the ratio of the error current ΔI to the photocurrent I cannot be ignored, and the error Δx of the position output Vx is There was a problem that the detection accuracy was low. In order to solve this problem, if the resistance value Rt is increased by reducing the thickness of the transparent resistance layer 3, the ratio of the error current ΔI to the photocurrent I becomes small, but the thickness of the transparent resistance layer 3 decreases. Since the accuracy is impaired, the position detection error ends up being similarly large.

Furthermore, even if the transparent resistance layer 3 is formed of a thin wire resistor to increase the resistance value Rtx, the error current ΔI will similarly become small. However, within the light irradiation area of the a-Si photovoltaic layer 4,
The region that contributes to photocurrent is only the portion where a-Si photovoltaic layer 4 and transparent resistance layer 3 overlap, and when the overlapping area is small, photocurrent I with respect to the amount of incident light also becomes small. Eventually, the ratio of error current ΔI to photocurrent I becomes similarly large, and furthermore, R(Ia
On the contrary, the ratio of +Ib) becomes small, and the position detection error becomes large. The same applies to the Y coordinate direction.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a two-dimensional optical position detector that can improve the accuracy of position detection with respect to a light incident position.

[0020]

[Means for Solving the Problems] A two-dimensional optical position detector of the present invention is a two-dimensional optical position detector in which a resistive layer, at least one of which is a transparent resistive layer, is provided on the upper and lower surfaces of a photovoltaic layer. Each resistor layer consists of a pattern consisting of a large number of sheet resistors and thin wire resistors connecting adjacent sheet resistors, and at least the sheet resistances of each resistor layer pattern are the same on the upper and lower sides. be.

[0021]

[Operation] The two-dimensional optical position detector of the present invention detects the position of incident light incident on a photovoltaic layer by each resistor layer composed of a large number of sheet resistors and thin wire resistors connecting adjacent sheet resistors. Detection is performed using a photocurrent that flows into and out of the detection electrode provided on each resistance layer via the resistive layer.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. In each figure, the same or equivalent parts are given the same reference numerals. FIG. 1 is a block diagram of a two-dimensional optical position detector according to an embodiment of the present invention, in which (a) is a perspective view, and (b) is an O-O
FIG. FIG. 2 is a diagram showing an example of a pattern of a resistive layer of the two-dimensional optical position detector according to the embodiment.

In this embodiment, the basic structure of the two-dimensional optical position detector A is the same as the conventional one, but the transparent resistance layer 3 is different. In FIG. 1, first, indium tin oxide (ITO) or tin oxide (SnO2) is formed into a film with a thickness of several hundred to thousand angstroms by sputtering or the like on a substrate 1 made of, for example, transparent glass. form.

Next, an a-Si photovoltaic layer 4 with a thickness of several thousand angstroms is formed on one of the transparent resistors in the order of P layer, I layer, and N layer by vapor deposition such as plasma CVD or sputtering. layer 3
Stack them with a width narrower than the width of the

Furthermore, ITO or SnO2 is formed into a film with a thickness of several hundred to 1,000 Å by sputtering or the like to form an a-S
i The other transparent resistive layer 3 is laminated to a width narrower than the PIN layer of the photovoltaic layer 4. Finally, detection electrodes 2a, 2 made of Al etc.
A two-dimensional optical position detector A is manufactured by forming pairs of layers b, 2c, and 2d perpendicularly to both ends of each transparent resistance layer 3 by vapor deposition or the like. At this time, each of the transparent resistor layers 3 includes a large number of sheet resistors 32 and a thin wire resistor 3 connecting between adjacent sheet resistors 32.
1, and the planar resistors 32 are the same on the upper and lower sides.

As shown in FIG. 2, the transparent resistance layers 3 provided on the upper and lower surfaces of the a-Si photovoltaic layer 4 each include a large number of sheet resistors 32 and thin wires connecting adjacent sheet resistors 32. It is composed of a resistor 31 shaped like a resistor 31. In the case of this embodiment, the sheet resistors 32 have a square shape with each surface having approximately the same size and are arranged in a matrix, and the sheet resistors 32 at the X coordinate between the detection electrodes 2a and 2b are The intermediate portions of each side are connected to each other by thin wire resistors 31 in the X-axis direction, which is the opposing direction of the electrodes 2c and 2d.
are similarly connected by a thin wire resistor 31 in the Y-axis direction, which is the direction in which the detection electrodes 2c and 2d face each other. Further, among the sheet resistors 32, the sheet resistors 32 adjacent to the detection electrodes 2a, 2b, 2c, and 2d are superimposed and connected to the adjacent sensing electrodes 2a, 2b, 2c, and 2d via the thin wire resistors 31, respectively. ing.

It is advantageous in terms of resolution to set the width between the sheet resistors 32 (portions where no resistors are formed) to be smaller than the diameter of the incident light; however, the diameter of the incident light is usually the area of the sheet resistors 32. It is not necessary to set it to an extremely small value.

The sheet resistance 32 and thin wire resistance 31 of the transparent resistance layer 3 may be determined as follows. That is, the area of the luminous flux incident on the a-Si photovoltaic layer 4 is S, the average illuminance is E, the photocurrent conversion efficiency is k, and the overlapping area ratio of the transparent resistance layer 3 to the a-Si photovoltaic layer 4 is m. Then, the average photocurrent I
is given by I=k・m・S・E. Here, if we pay attention only to the X coordinate, the offset voltages ΔVa and ΔV of the current-voltage converters 61a and 61b in the position detection circuit 6
b, the superimposition area ratio m is set so that the average photocurrent I becomes the following equation 6 using the predetermined error tolerance α (<<1), that is, the following equation 7 according to the equation 5. demand.

[0029]

[Math 6]

[0030]

[Math 7]

Further, from the above equation 4, the total resistance value Rt of the transparent resistive layer 3 is expressed as the following equation 8 using the error tolerance β (<<1), that is, in the above equation 5, the error current Δ
The sizes of the sheet resistor 32 and the thin wire resistor 31 are determined so that I>>ΔI with respect to I, and the total resistance value Rt is adjusted. However, at least the sheet resistance 32 on the Y coordinate is formed so as to match the sheet resistance 32 on the X coordinate one front and the other, that is, top and bottom.

[0032]

[Math. 8]

That is, according to this embodiment, the total resistance layer Rt of each transparent resistance layer 3 is approximately 10 times smaller than that of the conventional single-sided resistance layer.
The value can be approximately 100 times higher, and the superimposed area ratio m can be increased compared to the case where the resistance value Rt is simply increased by using a thin wire as the resistance layer, so the photocurrent I with respect to the amount of incident light can be increased.
The ratio of the photocurrent I to the error current ΔI can be made larger than that of a conventional two-dimensional optical position detector without significantly reducing the error current ΔI, and the position detection accuracy can be greatly improved.

FIGS. 3 to 5 show examples of other patterns of the transparent resistance layer 3. In FIG. 3, each transparent resistor layer 3 includes a large number of square resistors 32 arranged in a matrix with each surface having approximately the same size, and a layer between adjacent resistors 32 including diagonally. It is composed of thin wire resistors 31 connected between the corners.

In FIG. 4, only the transparent resistive layer 3 of the pattern shown in FIG. 3 is rotated by 45°.

In FIG. 5, the transparent resistance layer 3 includes a large number of hexagonal hexagonal resistors 32 arranged in a honeycomb pattern, each side having approximately the same size, and connecting the adjacent corner portions between the adjacent sheet resistors 32. It is composed of a thin wire resistor 31 connected between the two. In this case, the planar resistors 32 on the outer periphery are also directly connected to the detection electrodes 2a, 2b, 2c, and 2d in an overlapping manner, or are connected through the thin wire resistors 31 in an overlapping manner, as in the case of FIG. .

In the case of the pattern examples shown in FIGS. 3 to 5, the sheet resistors 32 and the thin wire resistors 31 are provided so as to coincide above and below the a-Si photovoltaic layer 4.

As another embodiment, on a substrate of an opaque resin such as epoxy or polyimide having a smooth surface, a resistive layer having the same pattern as the transparent resistive layer of the above embodiment, a-
a Si photovoltaic layer, a pattern of the resistive layer and the a-Si
A transparent resistive layer having a matching pattern above and below the photovoltaic layer, and a pair of detection electrodes each perpendicular to both ends of the resistive layer and the transparent resistive layer are laminated. In this case, the a-
The Si photovoltaic layer is formed into a PIN structure on the resistive layer in the order of N layer, I layer, and P layer. In this embodiment as well, the same effect as the embodiment of FIG. 1 can be obtained, and when the substrate is made of resin, a position detection circuit 6 for the two-dimensional optical position detector A shown in FIG. 7 is provided on the substrate. There are advantages that can be implemented. In each of the above-mentioned embodiments, the operation of the two-dimensional optical position detector A and the like is obvious from the conventional example, so the explanation thereof is omitted.

[0039]

As described above, according to the present invention, a resistive layer, at least one of which is a transparent resistive layer, is provided on the upper and lower surfaces of a photovoltaic layer, and the resistive layer is adjacent to a large number of sheet resistors. It is composed of a thin wire resistor connecting the sheet resistors, and is configured so that at least the sheet resistance of each resistor layer is the same on the upper and lower sides, so that the resistance value of the resistor layer, the photovoltaic layer, and the resistor layer are The resistive layer can be set so that the overlapping area ratios of both of the resistive layers are equal to or higher than a predetermined value, and the position detection accuracy for the light incident position can be improved.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing a two-dimensional optical position detector according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a pattern of a transparent resistive layer of the two-dimensional optical position detector of the embodiment.

FIG. 3 is a diagram showing an example of a pattern of a transparent resistive layer in another example.

FIG. 4 is a diagram showing an example of a pattern of a transparent resistive layer in another example.

FIG. 5 is a diagram showing an example of a pattern of a transparent resistive layer in another example.

FIG. 6 is a configuration diagram showing a conventional two-dimensional optical position detector.

FIG. 7 is a configuration diagram of a position sensor using a two-dimensional optical position detector.

[Explanation of symbols] 1 Substrates 2a, 2b, 2c, 2d Detection electrode 3 Transparent resistance layer 4 a-Si photovoltaic layer (photovoltaic layer) 31 Thin wire resistor 32 Planar resistor

Claims (1)

[Claims] 1. A resistive layer, at least one of which is a transparent resistive layer, is provided on the upper and lower surfaces of the photovoltaic layer, a detection electrode is provided on each of the resistive layers, and the photovoltaic layer is connected to the photovoltaic layer through the transparent resistive layer. In a two-dimensional optical position detector that detects the position of incident light incident on the detection electrode by photocurrent flowing into and out of each of the detection electrodes, each of the resistance layers has a plurality of planar resistors and a plurality of planar resistors adjacent to each other. 2. A two-dimensional optical position detector, characterized in that the two-dimensional optical position detector is comprised of a pattern made up of thin wire-shaped resistors that connect the resistive layer patterns, and that at least the planar resistors of each of the resistive layer patterns are the same on the upper and lower sides.