JPH0315920A - Coordinate input device - Google Patents

Abstract

PURPOSE:To prevent the error of coordinate input by providing a means judging the presence/absence of coordinate input from the output signal of a light- receiving element constituting a coordinate input device with a means eliminating the influence of reflected light in the other two confronting sides. CONSTITUTION:The subject device is constituted in such a way that erroneous judgement caused by the influence of reflected light is eliminated by providing a second threshold Th2 with respect to the output signal of a phototransistor PT1 being the photodetector where reflected light caused by an Y-axis side 101 is affected. In the case of no coordinate input, the output signals of phototransistors PT1-PT4 all exceed a first threshold Th1 being a common threshold, and the output signal exceeds a second threshold Th2 provided to judge the output of the phototransistor as for the photo transistor PT1 where reflected light is inputted. Thus, it is judged to be no coordinate input in such a case. In the case of the input of the coordinate, the judgement of an erroneous non-detection state is eliminated by providing the second threshold Th2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a coordinate input device, and in particular, a two-dimensional coordinate input surface having a plurality of light emitting elements and light receiving elements on at least one of the opposite sides of the input surface. The present invention relates to a coordinate input device in which a set of elements is arranged and an input coordinate signal is obtained by detecting that a light signal from the light emitting element in any of the sets does not reach a corresponding light receiving element. [Prior Art] This type of coordinate input device is placed in front of an image display device such as a CRT or LCD and is used for inputting coordinates into a computer, etc., and is equipped with a light emitting element on the outer periphery of the front surface of the screen of the CRT or the like. A large number of sets of light receiving elements are arranged facing each other, the light emitting element and the light receiving element are selectively driven and scanned, and coordinate signals are obtained by detecting that the light beam is interrupted by a finger or the like during this scanning. It is something.

The configuration and operation of a conventional coordinate input device will be described below with reference to FIGS. 8 and 9.

FIG. 8 is an overall configuration diagram illustrating a conventional coordinate input device;
FIG. 9 is an operational waveform diagram.

In FIG. 8, a large number of light emitting elements, namely light emitting diodes L1 to Lm and L(m+1) to Ln, are arranged on two adjacent sides of the outer periphery of the display surface of an image display device such as a CRT, and these light emitting diodes are opposed to each other. Phototransistors PT1 to PTm and PT(m+1) to PTn, which are light receiving elements, are arranged on the other two adjacent sides.

Here, light emitting diodes L1 arranged on the horizontal side
~Lm and the phototransistor PTI~PTmO group are set as the X coordinate, and the light emitting diode L (
m+1)~Ln and phototransistor PT (m+1)
~PTn (hereinafter referred to as phototransistor PTI'~P
(sometimes displayed together with Tn) is the Y coordinate. Light emitting diodes L1 to Lm. L (m+1) ~Ln(
Hereinafter, the cathodes of the light emitting diodes Ll-Ln (sometimes referred to collectively as the light emitting diodes Ll-Ln) and the phototransistors PTI to PT
The emitters of n are installed together. Furthermore, the anodes of the light emitting diodes L1 to Ln are normally open switching elements S.
The switching elements SL!=SLn are connected to one end of each of the switching elements SL!=SLn, and the other ends of the switching elements SL!=SLn are connected in common to the emitter of the driving transistor Q.The switching elements SLI to SL mentioned above
A first switching circuit l is configured including n.

The collectors of the phototransistors PTI to PTn are connected to one ends of normally open switching elements 31 to Sn, respectively, and the other ends of these switching elements 81 to Sn are connected in common to the amplifier section 2. Further, a second switching circuit 3 includes switching elements 31 to Sn. Note that the collector of the driving transistor Q is connected to the driving power supply V. Light emitting diode L1
~Ln, phototransistor PTI~PTn. The first switching circuit 1, the second switching circuit 3, the amplifying section 2, and the driving transistor Q constitute a coordinate detecting section.

Furthermore, an operation start signal Sc is applied to the driving transistor Q and the counter circuit 4 from a host computer (not shown).

The counter circuit 4 starts counting operation by inputting the operation start signal Sc, outputs a pulse signal P for each count,
Output count data Dc.

This pulse signal P is given to the first switching circuit l and the second switching circuit 3. These switching circuits are connected to switching elements 31 and SLI, S2 and SL by a decoder (not shown), etc.
2, ---Sn and SLn are made to correspond to each other and are closed in sequence, and the light emitting diodes L1 to Ln are sequentially driven to output optical signals. Here, the driving transistor Q is supplied with the operation start signal SC and is in an operating state.

In this structure, if the light emitted from the light emitting diode is not interrupted, the corresponding phototransistor becomes conductive upon reception of light, and when the operator interrupts the optical path with a finger or the like, the blocked phototransistor becomes non-conductive. According to the conduction and non-conduction (cutoff) of the phototransistors PTI to PTn, the waveform shaping section 5 outputs two signals as shown in FIG. 9(a).
A value signal is output. The waveform output shown in (a) is an example when the light beams from the light emitting diodes L5 and L(m+6) are blocked.

The output of the waveform shaping section 5 is input to the comparison section 6.

A pulse signal P is input from the counter circuit 4 to this comparator 6, and when the output from the waveform shaping circuit 5 is not input to this comparator 6 at the time when this pulse signal P is input,
The comparison section 6 outputs the storage signal Sm to the storage section 7. 9th
Figure (b) is a waveform output from the comparator 6, and shows that the storage signal Sm is output at the X coordinate of "5" and the Y coordinate of rm+6J. The storage section 7 to which the storage signal Sm is supplied stores the count data Dc output from the counter circuit 4 at the time when the storage signal Sm is input, and the count data Dc stored in the storage section 7 is sent to the output control section 8. Sent. Then, the output control section 8 calculates appropriate coordinates from the count data Dc and transfers the calculated coordinates to the host computer as a coordinate signal.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, the light emitting element and the light receiving element arranged on the other two opposing sides that are substantially perpendicular to the one opposing two side on which the set of the light emitting element and the light receiving element are arranged are arranged. Regarding this, the optical signal from the light emitting element may be reflected on at least one of the other two opposing sides and input to the light receiving element. In particular, two opposite sides of one side and two opposite sides of the other side
This phenomenon is remarkable between the light emitting element and the light receiving element which are arranged adjacent to the side.

FIG. 7 is an explanatory diagram of problems caused by the prior art, and shows 10
0 is the coordinate input device, 101 is the vertical side (Y-axis side), 201
and 202 are horizontal sides (two opposite sides in the horizontal direction: X-axis sides), L
l~L4 are light emitting elements (light emitting diodes), PT1-PT
4 is a light receiving element (phototransistor), and Rl to R4 are light emitting diodes L1 to L4 to phototransistor PT.
Rl' is a light beam that goes straight to I to PT4, Rl' is a light beam that is reflected from a light emitting diode placed adjacent to the Y-axis side to the Y-axis side 101 and input to the phototransistor, Di is a drive signal for the light-emitting diode, and Do is a phototransistor. The output signal from the transistor, Th is a threshold value for determining coordinate input detection, and IN is a coordinate input (such as an operator's fingertip).

In the figure, (a) shows the case where there is no coordinate input, and (b) shows the case where there is no coordinate input.
indicates that there is coordinate input.

When there is no coordinate input, all the lights 41R1-R4 from the light emitting diodes L1-L4 driven by the drive signal Di are input to the phototransistors PTI-PT4, and the output signal of the phototransistor becomes Do. Here, the reason why the output signal corresponding to the phototransistor PTI adjacent to the Y-axis side 101 is higher than the level of the output signal corresponding to the other phototransistors is the light emitting diode L.
This is because a portion R1'' of the light beam from 1 is reflected to the Y-axis side and input.

Since the output signals corresponding to the respective phototransistors of the output DO all exceed the threshold Th in FIG. 2A, it is determined that there is no coordinate input (input non-detection).

On the other hand, in (b), when there is a coordinate input IN, the light rays traveling straight from the light emitting diodes Ll and L2 toward the phototransistors PTl and PT2, respectively, are at the coordinate input IN.
The input should be detected at the positions of the PTI and PT2. However, for the phototransistor PTI, if the light %i R 1 ' is reflected and input to the Y-axis side 101, the output signal of the corresponding phototransistor PTI exceeds the threshold as shown in the figure, and as a result, the input There was a problem in that it was not detected and it was incorrectly determined that there was no coordinate input at the position of the light emitting diode L1 and phototransistor PTIO set. In addition, in the figure, a pair of light emitting diodes and a phototransistor adjacent to the Y-axis side 101 has been explained, but this problem is not limited to the above pair, but is similar to that of a phototransistor into which light reflected by the Y-axis side is input. There is a problem, and the figure shows not only the pair of light emitting diode and phototransistor placed on two opposite sides of the X axis, but also the pair of light emitting diode and phototransistor placed on two opposite sides of the y axis. It also occurs due to reflected light from the X-axis side.

It is an object of the present invention to solve the problems of the prior art described above, and to obtain coordinates generated by light rays from a light emitting diode on one two sides of a coordinate input surface being reflected on the other two sides and input to a corresponding phototransistor. An object of the present invention is to provide a coordinate input device that prevents input errors.

[Means to solve the problem]

The above object is achieved by providing means for eliminating the influence of the reflected light from the other two opposing sides in the means for determining the presence or absence of coordinate input from the output signal of the light receiving element constituting the coordinate input device.
Alternatively, this can be achieved by providing means for changing the light emitting ability of a light emitting element relative to other light emitting elements so as to eliminate the influence of the reflected light.

4, 5, and 6 are diagrams explaining the principle of the present invention, and the same reference numerals as in FIG. 7 correspond to the same parts.

FIG. 4 shows that a second threshold value Th2 is provided for the output signal of the photo resistor PT1, which is a light-receiving element affected by the reflected light from the Y-axis side 101, to prevent erroneous judgments due to the influence of the reflected light. This was done to eliminate it. Figure (a) shows the case where there is no coordinate input, and the output signals of the phototransistors PTI to PT4 are the first
For the phototransistor PTI to which the reflected light is input, it also exceeds the second threshold Th2 provided for determining the output of this phototransistor.

Therefore, in this case, it is determined that there is no coordinate input. Figure (b) shows the case where there is coordinate input, and the second threshold Th2 is provided for the output signal of the phototransistor PTI to which the reflected light on the Y-axis side is input, as explained in the prior art. This will not result in a false non-detection status determination.

In FIG. 5, the amplification factor of the amplification means for amplifying the output signal of the phototransistor PTI, which is a light receiving element affected by the reflected light from the Y-axis side 101, is set smaller than that of the other phototransistors. , so that the levels of the output signals of the phototransistors in the case of (a) without coordinate input all exceed the determination threshold Th, and the coordinate input IN
In such a case, the level of the output signal of the phototransistor PTI, which is a light-receiving element affected by the light reflected by the Y-axis side 101, is prevented from exceeding the threshold value, as shown in FIG. 4(b).

Figure 6 shows the case (a) where there is no coordinate input by setting the light emitting efficiency of the light emitting diode L1 facing the phototransistor PTI, which is affected by the reflected light from the Y-axis side 101, to be smaller than that of the other light emitting diodes. If the output signals of all phototransistors exceed the determination threshold Th and there is a coordinate input IN, then the Y-axis side 10 as shown in (b)
The level of the output signal of the phototransistor PTI, which is a light-receiving element that is affected by the reflected light by the light reflected by 1, does not exceed the threshold value.

[Effect]

Among the plurality of pairs of light emitting elements and light receiving elements arranged on two opposite sides of the input surface constituting the coordinate input device, light rays from the light emitting elements are applied to the other two opposite sides that are substantially orthogonal to (adjacent to) the two opposite sides. The determining means for determining the presence or absence of coordinate input from the output signal of a light receiving element located at a position where the reflected light is input is configured such that the influence of the reflected light can be ignored, or the intensity of the light ray from the light emitting element is A configuration in which the output of the light receiving element that receives the reflected light has the same signal level as in the case where the reflected light does not exist prevents errors in coordinate input determination.

〔Example〕

Embodiments of the invention will now be described with reference to a brief description of the drawings.

FIG. 1 is an overall configuration diagram illustrating a first embodiment of a coordinate input device according to the present invention, and the configuration of the coordinate input portion and its basic operation are the same as those described in FIG. 8 above. , adjacent 2 on the outer periphery of the display surface of an image display device such as a CRT
A large number of light emitting diodes L1 to Lm and l(m+1> to Ln, which are light emitting elements, are arranged on one side, and phototransistors PTI to PTm and PT, which are light receiving elements, are arranged on the other two adjacent sides opposite to these light emitting diodes. (m+1
) to PTn are arranged.

Here, similarly to FIG. 8, light emitting diodes L1 to Lm and phototransistors PTI are arranged on the horizontal side.
The set of ~PTm is set as an X coordinate, and the set of light emitting diodes l(m+1) to Ln and phototransistors PT(m+1) to PTn arranged on the vertical side is set as a Y coordinate.

Light emitting diodes L1 to Lm. The cathodes of L (m+1) to Ln and the emitters of phototransistors PTI to PTn are placed together. In addition, light emitting diodes L1 to L
The anode of n is a normally open switching element SLI~SLn
These switching elements S
The other ends of LI to SLn are connected in common to the emitter of the driving transistor Q. A first switching circuit 1 includes the switching elements SLI to Sun described above. The collectors of the phototransistors PTI-PTn are each connected to one end of normally open switching elements 31-Sn, and the other ends of these switching elements 31-Sn are commonly connected and connected to the amplifier section 2. Further, a second switching circuit 3 includes switching elements S1 to Sn. Note that the collector of the driving transistor Q is connected to the driving power source (2). Light emitting diode L1
~Ln, phototransistors PTI to PTn, the first switching circuit 1, the second switching circuit 3, the amplifier section 2, and the driving transistor Q constitute a coordinate detection section.

Furthermore, an operation start signal Sc is applied to the driving transistor Q and the counter circuit 4 from a host computer (not shown).

The counter circuit 4 starts counting operation by inputting the operation start signal Sc, outputs a pulse signal P for each count,
Output count data Dc.

This pulse signal P is given to the first switching circuit 1 and the second switching circuit 3. These switching circuits are connected to switching elements SL and SLI, 32 and SL by a decoder (not shown), etc.
2. . . . Sn and SLn are made to correspond to each other and are sequentially closed, and the light emitting diodes L1 to Ln are sequentially driven to output an optical signal.

Here, the driving transistor Q is supplied with the operation start signal SC and is in an operating state.

This I! In the precept, if the light emitted by a light emitting diode is not interrupted, the corresponding phototransistor becomes conductive when it receives light, and if the operator interrupts the optical path with his or her finger, the blocked phototransistor becomes nonconductive. Conduction and non-conduction (blocking) of these phototransistors PTI to PTn
Accordingly, a binarized signal is output from the waveform shaping determination section 50.

The output of the waveform shaping determination section 50 is input to the comparison section 6. A pulse signal P is input from the counter circuit 4 to this comparison section 6, and when the output from the determination waveform shaping section 50 is not input to this comparison section 6 at the time when this pulse signal P is input, the comparison section 6 The storage signal Sm is output to the storage section 7.

The storage section 7 to which the storage signal Sm is supplied stores the count data Dc output from the counter circuit 4 at the time when the storage signal Sm is input, and the count data Dc stored in the storage section 7 is sent to the output control section 8. Sent out. Then, the output control section 8 calculates appropriate coordinates from the count data Dc and transfers them as coordinate signals to the host computer. The difference between the configuration in FIG. 1 and the configuration in FIG. 8 is that
The reason is that a waveform shaping determination section 50 is provided in place of the waveform shaping section 5 shown in FIG. The waveform shaping determination unit 50 includes a first waveform shaping unit 51 . Second waveform shaping section 52. It is composed of a switch 53, a constant memory 54, and a comparator 55. In the figure, as explained in FIG. 8 above, phototransistors PTI to PTs+ (
X-axis side) and phototransistors PT(s+1) to PTn
The received light signal outputted in time series from the amplifying section 2 is amplified to a predetermined level and input to the waveform shaping determining section 50. The structure and operation of the waveform shaping determination section 50 will be explained below. The waveform shaping determination section 50 has a first waveform shaping section 51 and a second waveform shaping section 52 that receive the signal from the amplification section 2 as input.
The waveform shaping section 51 sets the first threshold Thl shown in FIG.
is used as a reference value to shape the output waveform of the amplifying section 2 to produce a binary signal, which is applied to the switch 53, and the second waveform shaping section 5
2 also shapes the output waveform of the amplifying section 2 using the second threshold Th2 shown in FIG.
Give to 3.

A count value of the counter circuit 4 is set in the constant memory 54, which corresponds to a scanning position for scanning a combination of a light emitting diode and a phototransistor that is affected by reflection from an adjacent side. In the configuration shown in FIG. 1, for example, a combination of a light emitting diode and a phototransistor (Ll-PTL) arranged closest to the adjacent side. (Lm-PT+++).
(Ln−PTn), (L (m+1> −
A count value of the counter 4 corresponding to the scanning position of PT(m+1)) is set.

The constant memory 54 supplies the set value to the comparator 55, and when the count value of the counter circuit 4 falls to either of the set values, outputs one switching signal T1 to the switch 53 for second waveform shaping. The output of section 52 is output to comparison section 6. Also,
When the count value of the counter circuit 4 does not match any of the set values, the other switching signal T2 is applied to the switch 53, and the output of the first waveform shaping section 51 is applied to the comparison section 6.

As shown in FIG. 4(a), the reflected light beam R 1° from the light emitting diode L1 by the Y-axis side 101, which is the adjacent opposing side, is input to the corresponding phototransistor PT1, and its output level is different from that of the other side. Even if the output level is higher than the output level from the phototransistor, this light emitting diode L1
At the time of scanning of the phototransistor PTI paired with the phototransistor PTI, one of the count data of the counter 4 and the count value set in the constant memory 54 match, and the second comparison output T2 outputs the switch 53 to the second waveform shaping section 52. As shown in FIG. 4(b), by switching to the second threshold Th
2 is performed. Then, another phototransistor (PT
2, PT3, PT4. ), none of the count values of the set values of the constant memory 54 match the count values of the counter circuit 4, so the comparator 55 gives the comparison output T1 to the switch 53, is switched to the output side of the l-th waveform shaping section 5l, and as shown in FIG. 4(b), the divisor waveform processing is performed using the first threshold Thl as a reference. In addition, in FIG. 1, the combination of a light emitting diode and a phototransistor that is affected by reflection from adjacent opposing sides is expressed as (Ll-
PTI), (Lm-PTm), (Ln
-PTn). (L (m+1)-PT(m+1))
The explanation was given assuming that there are four groups of If the reflections on the opposite sides of the X-axis are different, the number of waveform shaping sections should be processed using different level thresholds for each axis as the reference value, depending on the difference in the level of the output signal due to the influence. Furthermore, a pair of switching devices may be added so as to output a switching signal at the scanning time of the affected phototransistor corresponding to each axis of the constant memory.

Furthermore, if there are additional pairs of light emitting diodes/phototransistors that are affected by reflections from adjacent opposing sides, the count value set in the constant memory 54 may be set to a corresponding number.

As described above, in this embodiment, the threshold value, which serves as a judgment criterion in the binarization process for the photoelectric conversion output of the light emitting diode/phototransistor pair that is affected by the reflected light rays from adjacent opposing sides, is set based on the signal level caused by the reflected light rays. The problems in the prior art have been solved by switching to negligible values.

FIG. 2 is an overall configuration diagram illustrating a second embodiment of the coordinate input device according to the present invention, and the basic configuration and basic operation are the same as those in FIG. 8 above, and the configuration is similar to that in FIG. The difference is that a variable amplification section 20 is provided instead of the amplification section 2.

The variable amplification section 20 includes a l-th amplification section 21, a second amplification section 22,
It is composed of a switch 23, a constant memory 24, and a comparator 25. The first amplifying section 21 and the second amplifying section 22 amplify the outputs of the phototransistors PTI to PTn with different amplification factors, and supply the amplified signals to the waveform shaping section 5, which is shown in (a) of FIG. ), the amplification factor is set such that the level of the waveform shaping output signal (binarized signal) when there is no coordinate input exceeds the threshold Th for input determination at the output of the waveform shaping section 5. ing.

Switch 23. Constant memory 24. The configuration and operation of comparator 25 are as follows: switch 53 in FIG. Constant memory 54
, and comparator 55, so the explanation will be omitted.

In the same figure, when the count value of the counter 4 corresponding to the pair of light emitting diode and phototransistor placed at the scanning position affected by the reflected light rays of adjacent opposing sides is input to the comparator 25, the comparator 25 The coincidence output T2 is output to the switch 23, which is switched so that the output of the second amplification section 22 is applied to the waveform shaping section 5. The amplification factor of the second amplifier 22 is set smaller than the amplification factor of the first amplifier 21. For example, as shown in FIG. 5(b), the straight light beam R1 from the light emitting diode Ll is blocked by the coordinate input IN. , is set so that the output when the reflected light stripe R1' of the adjacent opposing side 101 is input to the corresponding phototransistor PTI is equal to or less than the input determination threshold Th.

Regarding the output signal of the light emitting diode/phototransistor pair, which is not affected by the reflected light rays from adjacent opposing sides, since the count value of the counter circuit 4 is not in the constant memory 24 at the time of scanning, there is no coincidence in the comparator 25. The output signal T2 indicating this mismatch is applied to the switch 23, and the switch 23 supplies the output signal of the second amplifier 22 to the waveform shaping section 5. As a result, the waveform shaping circuit 5 performs detection/non-detection processing of the coordinate input using the determination threshold Th, as shown in FIG. 5(b), and provides the processed signal to the comparator 6.

In addition, in FIG. 2, the combination of a light emitting diode and a phototransistor that is affected by reflection from adjacent opposing sides is expressed as (Ll-
PTI), (Lm-PTm), (l,
n - PTn). (L (m+1)−PT(m
+1)), and the degree of influence is the same, but if the reflections on the opposite sides of the V-axis and X-axis are different, the difference in output signal level due to that influence The number of amplifying sections is further increased to multiple levels so that each axis is processed with a different level of amplification factor, and a switching signal is output at the scanning time of the phototransistor affected by each axis of the constant memory. You can also add a switch to do this. Furthermore, if there are additional pairs of light emitting diodes/phototransistors that are affected by reflections from adjacent opposing sides, the count value set in the constant memory 54 may be set to a corresponding number. In this way, in the embodiment shown in FIG. 2, the amplification factor of the amplification section that amplifies the output signal of the phototransistor that is affected by the reflected light rays from the adjacent opposing sides is set to be higher than the amplification factor of the amplifier that amplifies the output of other phototransistors. The problem of the prior art described above is solved by making the output signal level of the phototransistor smaller and setting it to a value that does not cause the output signal level of the phototransistor due to the reflected light rays from the adjacent opposing sides to exceed the threshold value for input determination when coordinates are input. .

FIG. 3 is an overall configuration diagram illustrating a third embodiment of the coordinate input device according to the present invention, and since its basic configuration and operation are the same as those explained in FIG. 8, the explanation will be omitted. Omitted. The difference between the configuration in FIG. 3 and the configuration in FIG. 8 is that a switch 33. constant memory 31,
and a comparator 32.

In this figure, the count value set in constant memory 31 and the operation of comparator 32 are similar to those of the constant memory and comparator in FIGS. 1 and 2. A switch 33 connects resistors R1 and R2 (Rl > R2) with different resistance values to a comparator 32.
It is a light emitting diode/phototransistor pair that is switched by the output of
At the time of scanning, the light emitting efficiency of the light emitting diode is made lower than that of other light emitting diodes, thereby reducing the level of the output signal of the phototransistor caused by the reflected light beam.

That is, as shown in FIG. 6(a), the light emitting efficiency of the light emitting diode L1, which emits light to the phototransistor PTI, which is affected by the reflected light from adjacent opposing sides, is made lower than that of other light emitting diodes. As a result, as shown in FIG. 6(b), when coordinates are input, the output signal of the phototransistor is prevented from exceeding the determination threshold Th, thereby preventing the reflected light beam from causing an erroneous determination. At the time of scanning of the light emitting diode Ll, the count value of the counter circuit 4 and the set value of the constant memory 31 match, and a match signal T1 is applied from the comparator 32 to the switch 33, and the switch 33 selects a resistor with a large resistance value. A power supply is connected to the driving transistor Q via R1. Therefore, the light emitting diode Ll is driven with low efficiency, and the amount of light emitted by it is smaller than that of other light emitting diodes. Furthermore, at the time of scanning of the light emitting diode/phototransistor, which is not affected by the reflected light beam, the comparator 32 does not match the count value of the counter circuit 4 and the set value of the constant memory, so the comparator 32 outputs a discrepancy signal. T2 is output to the switch 33, and the switch 33 connects the power to the driving transistor Q via a resistor R2 having a small resistance value.

Thereby, it is possible to eliminate erroneous determination of coordinate input due to reflected light rays from adjacent and opposing sides.

In the embodiment shown in FIG. 3, the combinations of a light emitting diode and a phototransistor that are affected by reflection from adjacent opposing sides are (Ll-PTI), (Lm-PTm),
(Ln-PTn), (L (m+1)-PT
(m+1)], and each has the same degree of influence. However, if the reflections on the opposite sides of the Y-axis and X-axis are different, the difference in output signal level due to the influence , the number of resistances in the power supply circuit to the drive transistor Q is processed using a threshold value of a different level for each axis as a reference value, and the number of resistances of the light emitting diode/phototransistor that is affected by reflections from adjacent opposing sides is If there are more pairs, the count value set in the constant memory 54 may be set to a corresponding number.

〔Effect of the invention〕

As explained above, according to the present invention, the light emitting element arranged on the other two opposing sides adjacent to one of the two opposing sides on which the set of the light emitting element and the light receiving element is arranged, Regarding the element and the light-receiving element, it is possible to eliminate erroneous detection of coordinates due to an optical signal from the light-emitting element being reflected on at least one of the other two opposing sides and input to the light-receiving element.

[Brief explanation of the drawing]

1 is an overall configuration diagram illustrating a first embodiment of a coordinate input device according to the present invention, FIG. 2 is an overall configuration diagram illustrating a second embodiment of a coordinate input device according to the present invention, and FIG. The figure is an overall configuration diagram explaining the third embodiment of the coordinate input device according to the present invention, Figures 4, 5, and 6 are diagrams explaining the principle of the present invention, and Figure 7 is a problem with the prior art. 8 is an overall configuration diagram illustrating a conventional coordinate input device, and FIG. 9 is an operational waveform diagram of FIG. 8. 1...First switching circuit, 2...Amplifying section, 3...
...Second switching circuit, 4...Counter circuit, 6.
...Comparison section, 7.. Storage section, 8.. Output control section, 20.. Variable amplification section, 30.. Variable drive section,
50...Waveform shaping determination unit. Figure 4 Figure 5 Figure 6 Figure 7

Claims (4)

[Claims] (1) A plurality of sets of light-emitting elements are arranged on one side of at least one of the two opposing sides constituting the two-dimensional coordinate input surface, and light-receiving elements are arranged on the other side, facing each other with the two-dimensional plane interposed therebetween. , the plurality of sets of light-emitting elements and light-receiving elements are sequentially selectively switched and driven by a switching circuit in response to a pulse signal output from a counter circuit, and are opposed to the optical signal output from the light-emitting element selected by the switching circuit. A coordinate input device that stores count data output from the counter circuit in a storage section when the output signal of the light receiving element does not reach a determination reference value, and obtains a coordinate signal from this count data, based on the output of the light receiving element. The determining means for determining the presence or absence of coordinate input is also capable of receiving an optical signal inputted by a light emitting signal from the light emitting element being reflected on one of the two opposing sides and the other two opposing sides adjacent to the light emitting element. 1. A coordinate input device comprising a determination processing switching means for switching between input determination processing for an output signal of a light receiving element disposed at a position and input determination processing for outputs of other light receiving elements. (2) In claim (1), the determination processing switching means is a binarization threshold switching means, and the light emission signal from the light emitting element is applied to either of the other two opposing sides that are substantially orthogonal to the one opposing two sides. A first threshold value for signal processing of a binary signal based on the output of a light receiving element placed in a position where it can receive an input optical signal reflected by a crab, and a second threshold value based on the outputs of other light receiving elements. A coordinate input device characterized in that it is a threshold value switching means for switching between a second threshold value and a second threshold value for signal processing of a digitized signal. (3) In claim (1), the determination processing switching means inputs an optical signal in which a light emission signal from the light emitting element is reflected onto one of the other two opposing sides substantially orthogonal to the one opposing two sides. It is characterized by an amplification factor switching means for switching between the amplification factor of the amplification means for amplifying the output of the light receiving element arranged at a position where it can also receive light, and the amplification factor of the amplification means for amplifying the output of the other light receiving elements. coordinate input device. (4) A plurality of sets of light-emitting elements are arranged on one of at least one of the opposing sides constituting the two-dimensional coordinate input surface, and a plurality of sets of light-receiving elements are arranged on the other opposing side so as to face each other with the two-dimensional plane interposed therebetween, and from the counter circuit. The plurality of sets of light-emitting elements and light-receiving elements are sequentially selectively switched and driven by the switching circuit according to the output pulse signals, and the optical signal output from the light-emitting element selected by the switching circuit is outputted from the opposing light-receiving element. A coordinate input device that stores count data output from the counter circuit in a storage section when a binarized signal value based on the reference value does not reach a reference value, and obtains a coordinate signal from this counter data. The light emitting efficiency of the light emitting element corresponding to the light receiving element arranged in a position where the signal can also receive the optical signal reflected and input to the other opposing side that is substantially orthogonal to the one opposing side is calculated as the light emitting efficiency of the other light emitting elements. A coordinate input device characterized by being provided with a light emitting efficiency switching means for switching between light emitting efficiency and light emitting efficiency.