JPH0820211B2 - Two-dimensional position sensor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a two-dimensional position sensor that detects a position where light is applied.

[Conventional technology]

When digging in a tunnel or the like, it is necessary to accurately know the direction of excavation of the excavator. However, since the excavator is underground, it is difficult to visually recognize the direction of excavation. Therefore, in order to detect the direction of excavation of the excavator, a laser light source and a photodetector (position detector) are arranged in various places in the tunnel behind the excavator, and the laser light is detected in front and in the rear. The direction of the tunnel, the posture of the excavator, and the like are detected from the position of the laser light that is emitted toward the light receiver and strikes the light receiver. In recent years, a two-dimensional position sensor applying the principle of a silicon photodiode has been used as a position detector.

As shown in FIG. 13, this two-dimensional position sensor is provided with a P layer 12 and an N layer 14 with a depletion layer 10 in between, and an electrode 16, on a pair of opposing sides of the square P layer 12, Attach 18,
Electrodes 20 and 22 are attached to a pair of sides of the N layer 14 different from the side where the electrodes of the P layer 12 are provided. When this sensor is exposed to light, photocurrent is generated from that position, and each electrode 16, 1
The output is divided into 8, 20, and 22. Therefore, the current extracted from each electrode is subjected to voltage conversion and division using an arithmetic circuit, and is extracted as, for example, an XY coordinate voltage, and the position where light is applied is obtained.

[Problems to be Solved by the Invention]

However, in the above-described conventional two-dimensional position sensor, when the background light strikes, the photocurrent generated by the background light is also output together with the current by the signal light, and an error is likely to occur. Therefore, in order to reduce the influence of background light,
It is necessary to take measures such as strengthening the signal light.

Further, as shown in FIG. 14, when the disturbance light 24 and the signal light 26 strike at two or more positions on the sensor surface at the same time, it is impossible to separate the output of the disturbance light 24 and the signal light 26. The position where the light hits is output as the center of gravity 28 of the ambient light 24 and the signal light 26, and the position where the signal light 26 hits cannot be obtained.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and an object thereof is to provide a two-dimensional position sensor that is less affected by ambient light.

[Means for solving the problem]

In order to achieve the above-mentioned object, the present invention provides a plurality of second electrodes (Y-axis) intersecting with a plurality of first electrodes (X-axis) arranged in parallel. In a two-dimensional position sensor in which at least one of the two electrodes is a transparent electrode and a light receiving element is interposed between the first electrode and the second electrode, a control signal from a microcomputer is transmitted. Multiplexer to receive, light receiving element D1 to scan individually by sequentially opening and closing this multiplexer
1-Dnn, an amplifier that outputs the signal of the light receiving element one by one to the series and amplifies the output of the multiplexer,
It is characterized in that it is composed of the microcomputer for inputting the signal of the amplifier.

Further, a controller that receives a control signal from the microcomputer and outputs the control signal to the multiplexer may be provided between the microcomputer and the multiplexer.

Further, a comparator which inputs the signal of the amplifier and outputs the (0,1) signal to the microcomputer can be provided between the amplifier and the microcomputer.

[Action]

According to the present invention configured as described above, when light is incident on the light receiving element through the transparent electrode, a photocurrent is output to the first electrode and the second electrode which are in contact with the upper and lower surfaces of the light receiving element. . Therefore, by sequentially scanning the plurality of first electrodes and the second electrodes and extracting the signal, the position of the light receiving element on which the light is incident can be known. In addition, since the photocurrent output from each electrode is not divided and output, a large photocurrent is output, and a highly sensitive sensor that is not easily affected by ambient light can be obtained. Even if the ambient light and the signal light strike two or more positions on the sensor surface at the same time, each position where the light hits can be obtained, and the output current of the signal light can be separated from the current of the ambient light. , The position where the signal light hits can be obtained. Further, the shape and size of the cross section of the incident light can be recognized.

〔Example〕

A preferred embodiment of the two-dimensional position sensor according to the present invention,
Detailed description will be given according to the attached drawings.

FIG. 1 is a front view of a two-dimensional position sensor according to an embodiment of the present invention.

In FIG. 1, a two-dimensional position sensor 30 has a plurality of transparent electrodes Y _{1 to} Y _n provided on a transparent substrate 32 made of glass, ceramic or an organic material. The transparent electrodes Y _{1 to} Y _n are formed of conductive tin oxide / indium (ITO), tin oxide (SnO ₂ ), indium oxide (In ₂ O), etc. in a strip shape in the vertical direction (Y direction). Are arranged in parallel in the horizontal direction (X direction) at equal intervals. Further, above the transparent electrodes Y _{1 to} Y _n ,
A plurality of electrodes X _{1 to} X _n are transparent electrodes via a light receiving element described later.
It is formed orthogonal to Y _{1 to} Y _n . The electrodes X _{1 to} X _n are gold,
It is formed in a band shape by a metal such as silver, copper, or aluminum, and is arranged in the Y direction at equal intervals.

As shown in FIG. 2, light receiving elements D _{11 to} D _nn are provided at the respective intersections of the transparent electrodes Y _{1 to} Y _n and the electrodes X _{1 to} X _n . A P layer 34, an I layer 36, and an N layer 38 are laminated on each of the light receiving elements D _{11 to} D _nn to form a PIN diode.

In the two-dimensional position sensor 30 configured in this manner, the transparent electrodes Y _{1 to} Y _n and the electrodes X _{1 to} X _n are connected to the pad electrode portion (not shown) provided in the peripheral portion of the transparent substrate 32, It is used by being connected to a peripheral circuit by a wire or a lead wire via the pad electrode portion. When detecting the output current (signal) of each of the light receiving elements D _{11 to} D _nn , the transparent electrodes Y _{1 to} Y _n are connected to the switches SY ₁ to SY _n as shown in FIG.
Connect electrodes X ₁ -X _n to switches SX ₁ -SX _n and switch SY ₁
To SY _n, performed by switching SX ₁ ~SX _n. That is, when the switch SX ₁ is closed, the light receiving elements D _{11 to} D _1n are connected to a calculator or the like (not shown), and by closing the switch SY ₁ , only the light receiving element D ₁₁ can be selected and an output signal can be obtained. Also, with switch SX ₁ closed, switch SY ₁
The light receiving element D by releasing the switch and closing the switch SY _2.
Only ₁₂ can be selected. In this way, by switching the switch SX ₁ ~SX _n and the switch SY ₁ to SY _n sequentially, it is possible to obtain an output signal of the light receiving elements D ₁₁ to D _1n.

A concrete detection circuit is configured as shown in FIG. 4, and in FIG. 4, the transparent electrodes Y ₁ to
Y _n is connected to each channel of the analog switch 40 for power supply, and the electrodes X _{1 to} X _n are connected to each channel of the analog switch 42 for signal extraction. Analog switch 40
The I / O common terminal of is connected to the power supply V _cc . An amplifier 44 that amplifies the detection signal is connected to the input / output common terminal of the analog switch 42, and the output signal of the amplifier 44 is input to the comparator 46. Controllers 48 and 50 are connected to the analog switches 40 and 42, respectively, and the controllers 48 and 50 control connection and disconnection between the input / output common terminal and each channel.

That is, each controller 48, 50 is connected to the microcomputer 56 via the buses 52, 54 as shown in FIG. 5, and receives a control signal from the microcomputer 56. Further, the controller 50 synchronizes with the switching signal of the analog switch 42 and the amplifier 44 and the comparator 46.
The signal is output to and, and the output signal of the comparator 46 is input to the microcomputer 56. The microcomputer 56 is supplied with a drive voltage from a stabilizer 58 connected to a power source _Vcc , and outputs detection data of the two-dimensional position sensor 30.

 The position where the light hits is detected as follows.

First, the microcomputer 56 sends a control signal to the controller 48, connects the channel to which the transparent electrode Y ₁ of the analog switch 40 is connected to the input / output common terminal,
The voltage V _cc is applied to the electrode Y ₁ . In addition, the microcomputer 56 uses an analog switch 42 via the controller 50.
Activated and connect the channel electrodes X ₁ of the analog switch 42 is connected to the input-output common terminal, the light-receiving element D ₁₁
The output signal of the above is input to the amplifier 44. The amplifier 44 amplifies the signal of the light receiving element D ₁₁ and sends it to the comparator 46. The comparator 46 is
Compare the input value with the set reference value and
If the light hits D ₁₁ , “H” is output, and if the light is not hit, “L” is output. The output signal of the comparator 46 is input to the microcomputer 56 via the controller 50 and stored in a memory (not shown) in the microcomputer 56.

When the microcomputer 56 obtains the data regarding the light receiving element D _11, it switches the analog switch 42 and stores the data regarding the light receiving element D ₂₁ in the memory in the same manner. Thereafter, similarly, each channel of the analog switch 42 is switched, data of the light receiving elements D _{31 to} D _n1 is collected via the electrodes X _{1 to} X _n , and stored in the memory.

The microcomputer 56, when the collection of data for the light-receiving element D ₁₁ to D _n1 is completed, as well as blocking the transparent electrodes Y ₁ switches the analog switch 40 from the power supply V _cc, connecting the transparent electrodes Y ₂ to the power source V _cc Light receiving element D _{12 to} D _n2
The voltage V _cc is applied to. Then, similarly to the case of collecting the data of the light receiving elements D _{11 to} D _n1 , the analog switch 42 is sequentially switched to store the data of the light receiving elements D _{12 to} D _{n2 in} the memory.

In this way, when the collection of the data of the light receiving elements D _{11 to} D _nn is completed, the microcomputer 56 calculates the center on which the light is applied from these data and outputs it to the output device.

As described above, in the embodiment, the output signals of the light receiving elements D _{11 to} D _nn provided at the intersections of the transparent electrodes Y _{1 to} Y _n and the electrodes X _{1 to} X _n are detected, and the conventional wide range is used. Unlike the case of dividing and outputting the photocurrent generated by the light hitting the light receiving element of the area, the influence of the disturbance light is small, and the disturbance light and the signal light can be separated.

In the above embodiment, the case where the light receiving elements D _{11 to} D _nn are laminated on the transparent substrate 32 in the order of P layer, I layer and N layer has been described. However, N layer, I layer and P layer are laminated in this order. May be. Further, in the above-mentioned embodiment, the case where the electrodes X _{1 to} X _n are formed of metal has been described, but the electrodes X _{1 to} X _n may be transparent electrodes. And, of course, a protective film may be provided on the upper surface of the two-dimensional position sensor 30.

First Example A square transparent glass plate with a side of 120 mm was placed in the Y direction (first
I with 1 μm heat and 100 μm width extended in the vertical direction)
100μ of TO transparent conductor in X direction (left and right direction in Fig. 1)
257 pieces are formed at m intervals to form transparent electrodes. Then
An N-type silicon semiconductor of 100 μm square and a thickness of 500 Å is fixed on the transparent electrode at 100 μm intervals. Then, a genuine semiconductor is fixed on the N-type silicon semiconductor by 5000Å to form an I layer, and a P-type silicon semiconductor is fixed on the I layer by 200Å to form a PIN-structured silicon light receiving element. Next, 257 electrodes having a thickness of 1 μm and a width of 100 μm extending in the X direction are formed by gold vapor deposition through the silicon light receiving element and across the transparent electrodes.

The amorphous Si: H (hydrogenated silicon) two-dimensional position sensor 30 created in this way has a transparent electrode 60 as shown in FIG.
The electrode 62 and the electrode 62 are connected to the circuit board 66 using the lead wire 64. Each electrode of the two-dimensional position sensor may be connected to the circuit board on every other side as shown in FIG. 6, or may be connected to the same side of each electrode as shown in FIG. You may Then, the input / output common terminal of the analog switch for power supply is connected to the power supply, and each channel is connected to the cathode of each silicon light receiving element. On the other hand, each channel of the analog switch for signal extraction and the output side (anode) of the light receiving element are connected via a capacitor. When the analog switch has 8 channels, the control terminal has 3 bits. In the case of a 16-channel analog switch, the control terminal has 4 bits.
If the number of analog switches used is 16 channels, 16 for power supply and 16 for signal extraction, 32 in total are required.

FIG. 8 shows one element taken out and shown. In FIG. 8, the channels of the analog switches 68 and 70 and the input / output common terminal CO are connected to the control terminals A, B, C, and
Perform with D. The control terminals A, B, C, D of each analog switch are connected to the computer 72,
The inhibit terminal INH is connected to shift registers 78 and 80 via inverters 74 and 76. Then, the shift registers 78 and 80 receive a control signal from the computer 72.
The input / output common terminal of the analog switch 70 for signal extraction is connected to the computer via the amplifier 44 and the comparator 46.
Connected to 72.

The computer 72 turns on one of the plurality of power supply analog switches and the signal analog switch, and turns off all the other analog switches. That is, the computer 72 connects the shift register 7 to the inhibit terminal INH of the analog switch 68 for power supply and the analog switch 70 for signal to which the light receiving element for taking out the signal is connected.
Apply "L" via 8 and 80 to turn it on, and inhibit terminals of all other analog switches.
Apply "H" to INH to turn it off. After that, a control signal is sent to the control terminal to capture the output signal of each light receiving element as described above.

Second Example A transparent glass plate having a side of 100 mm and a SnO ₂ transparent electrode having a thickness of 1 μm and a width of 50 μm extended in the Y direction, and having a thickness of 50 μm in the X direction.
Create 257 at m intervals. Then put a thickness of 2 on this transparent electrode.
Fix 00-Å, 50μm-square p-type silicon semiconductor at 50μm intervals. Next, a true semiconductor is fixed on the P-type silicon semiconductor to a thickness of 5000Å to form an I layer, and then an N-type silicon semiconductor is fixed on the P-type silicon semiconductor by 500Å to form a mesh-shaped silicon light receiving element having a PIN structure. To do. After that, an electrode having a thickness of 1 μm and a width of 50 μm, which extends in the X direction across the transparent electrode and passes over the light receiving element, has a thickness of 50 μm in the Y direction.
Formed by vapor deposition of 257 gold at intervals.

The amorphous Si: H thus created is connected to a circuit board using a lead wire. Then, as shown in FIG. 9, the input / output common terminal of the power supply digital multiplexer 82 is connected to the power supply _Vcc , and each channel is connected to the cathode of each light receiving element. Further, the anode of each light receiving element is connected to each channel of the signal digital multiplexer 86 via the comparator 84. Then, the input / output common terminal of the signal digital multiplexer 86 is connected to the computer for signal extraction. Instead of the comparator 84,
An operational amplifier may be used, or a comparator and an operational amplifier may be used together.

The control of the digital multiplexers 82 and 86 shown in FIG. 9 is performed by the computer as in the first embodiment.

Third Example A SnO ₂ transparent electrode having a thickness of 1 μm and a width of 100 μm, which was extended in the Y direction, was placed on a transparent glass plate having a side of 120 mm in the X-axis direction.
Create 257 lines at intervals of 00 μm. Then, on the entire surface of the transparent glass plate excluding the electrode part for taking out terminals, amorphous Si: H
Fix it. Then, electrodes having a width of 100 μm extending in the X direction are formed by vapor deposition of 257 pieces of gold at intervals of 100 μm in the Y direction. Then, the pad electrode portion is provided in the peripheral portion of the substrate,
The pad electrode portion is connected to the peripheral circuit using a wire or a lead wire.

The circuit of this embodiment is as shown in FIG. 10, in which the cathode is connected to the power supply V _cc via the switch AS ₂ , the switch AS ₁ is connected to the anode, and the signals selected by the switches AS ₁ and AS ₂ are selected. Only is taken as output. At this time, the signal extraction circuit is as shown in FIG. That is, the anode of the light receiving element is connected to the drain of the field effect transistor (FET) 90, the source is connected to the computer, and the gate is connected to the shift register 92. When a reverse bias is applied to the light receiving element, the drain of the FET 94 is connected to the power supply _Vcc , the source is connected to the cathode of the light receiving element, and the gate is connected to the shift register 96, as shown in FIG.

A voltage is applied and a signal is taken out by inputting a clock signal to the shift register and sequentially setting the gate to “H” from the first on the left side of the drawing to open between the drain and the source. Then, from the first 1 bit at the upper end of the left end of the transparent electrode, a signal is taken out bit by bit on the transparent electrode at the left end and sent to the computer as data in the Y-axis direction. 25 in the Y-axis direction
When the transmission of the 6-bit signal is completed, the data is sent to the computer in the same manner for the next second transparent electrode.

In this way, if all bits of data are input to the computer, the computer calculates based on the data and finds the position where the light is applied. The two-dimensional sensor shown in each example is Of course, either circuit may be used.

〔The invention's effect〕

As described above, according to the present invention, by providing the light receiving element between the intersecting electrodes, the influence of the ambient light can be reduced, and the output by the ambient light and the output by the signal light can be separated. it can.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment of a two-dimensional position sensor according to the present invention, FIG. 2 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is a signal of the two-dimensional position sensor according to the embodiment. 4 and 5 are explanatory views of an embodiment of a signal extraction circuit, FIGS. 6 and 7 are explanatory views of a method of connecting to a circuit board, and FIG. 8 is a first embodiment. FIG. 9 is an explanatory diagram of an example signal extraction method, and FIG. 9 is an explanatory diagram of a signal extraction method of the second embodiment.
FIG. 10 is an explanatory view of the principle of the signal extracting method of the third embodiment,
FIG. 11 is a signal extraction circuit diagram of the third embodiment, FIG. 12 is a voltage application circuit diagram of the third embodiment, FIG. 13 is a perspective view of a conventional two-dimensional position sensor, and FIG. It is operation | movement explanatory drawing of a two-dimensional position sensor. 30 …… two-dimensional position sensor, 32 …… transparent substrate, 34 …… P
Layer, 36 ...... I layer, 38 ...... N layer, Y ₁ ~Y _n ...... transparent electrodes, X ₁
~ X _n …… Electrode, D ₁₁ , D ₁₂ , D ₁₃ …… Light receiving element.

Claims (2)

[Claims] 1. A plurality of first electrodes (X) arranged in parallel.
Axis) and a plurality of second electrodes (Y-axis) are provided, and at least one of the first electrode and the second electrode is a transparent electrode, and the first electrode and the second electrode. A two-dimensional position sensor having a light receiving element interposed between the multiplexer and the electrode, the multiplexer being provided corresponding to each of the first and second electrodes and receiving a control signal from the microcomputer; Light receiving elements D11-Dnn to be individually scanned by opening and closing, an amplifier for outputting the signals of the light receiving elements one by one in series and amplifying the output of the multiplexer, and an analog signal of the amplifier (0,
1) A two-dimensional position sensor comprising a comparator for converting into a signal and the microcomputer for inputting the signal from the comparator. 2. A control signal from the microcomputer is received between the microcomputer and the multiplexer,
The two-dimensional position sensor according to claim 1, further comprising a controller that outputs a control signal to the multiplexer.