JP2988780B2 - Coordinate detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coordinate detecting device used for a personal computer, a word processor and the like.

[0002]

2. Description of the Related Art As a means for inputting handwritten characters and figures into a computer or word processor, for example, a liquid crystal display and an electrostatic induction type tablet are stacked, and the characters and figures are statically written as if we were writing on paper with a writing instrument. 2. Description of the Related Art A tablet device integrated with a display unit capable of inputting to an electric induction type tablet has been put to practical use. However, in this display unit integrated type tablet device, since the reflectance and the transmittance are different between the portion with and without the electrodes, the electrodes can be seen in a grid pattern on the display screen, causing a deterioration in the quality of the liquid crystal display. I have.

In view of the above, as a tablet that eliminates such disadvantages, a display integrated tablet device as shown in FIG. 9 has recently been proposed (Japanese Patent Application No. 3-46751). This display-integrated tablet device serves both as a display electrode of a liquid crystal display and a coordinate detection electrode of a capacitance-type tablet device. Then, as shown in FIG. 10, a coordinate detection period for detecting designated coordinates on the tablet and a display period for displaying an image are provided during one frame period, and coordinate detection and image display are performed in a time-division manner. I have.

In FIG. 9, a liquid crystal panel 1 has common electrodes Y _{1 to} Y _n (hereinafter, an arbitrary common electrode is described as Y) and segment electrodes X _{1 to} X _m (hereinafter, an arbitrary common electrode) arranged orthogonally to each other. , The segment electrode is described as X), and each pixel is formed in a region where each common electrode Y and the segment electrode X intersect.
That is, the liquid crystal panel 1 has pixels of n × m dots arranged in a matrix.

[0005] This display-integrated tablet device has the advantage that the grid-like electrode pattern is eliminated and is easier to see than the above-described liquid crystal display in which a capacitance type tablet is laminated. Since the electrode and the drive circuit are also used as the capacitive tablet, there is an advantage that the cost can be reduced and the size and weight can be easily reduced.

The display-integrated tablet device operates as follows. That is, the common drive circuit 2 for driving the common electrode Y and the segment drive circuit 3 for driving the segment electrode X are provided with a switching circuit 4
Are connected to the display control circuit 5 and the detection control circuit 6 via the. The switching circuit 4 is controlled by the control circuit 7 to output an output signal from the display control circuit 5 to the common drive circuit 2 and the segment drive circuit 3 during the display period, and to output the detection control circuit 6 during the coordinate detection period. Are output to the common drive circuit 2 and the segment drive circuit 3. In FIG. 9, the switching circuit 4, the display control circuit 5, the detection control circuit 6, and the control circuit 7 are represented by being divided into respective blocks. However, in an actual circuit, each of the above circuits is implemented as an LSI (Large Scale Integrated Circuit), and cannot be strictly divided into blocks as described above in terms of form.

During the display period, the shift data s is output from the shift data output terminal S of the display control circuit 5, the inverted signal fr is output from the inverted signal output terminal FR, and the clock signal cp1 is output from the clock output terminal CP1. The clock signal cp2 is output from the clock output terminal CP2.
There is output, the display from the data output terminal D0~D3 data D ₀ to D ₃ is output.

The clock signal cp1 is a clock signal having a period of displaying one row of pixels as a cycle. The clock signal cp1 is output to the clock input terminal YCK of the common drive circuit 2 via the output terminal CP10 of the switching circuit 4 as the clock signal cp1o. It is input to the latch pulse input terminal XLP of the segment drive circuit 3. The shift data s, which is a pulse signal for selecting a specific common electrode Y, is supplied to the shift data input terminal DIO1 of the common drive circuit 2 as the shift data so via the output terminal SO of the switching circuit 4, and the clock signal cp1o. Input in synchronization with.

When the shift data so is input to the common drive circuit 2, the pulse position of the shift data so is shifted by the shift register in synchronization with the clock signal cp1o, and the output of the common drive circuit 2 corresponding to the shift position is output. driving pulses of common electrode drive signal is applied to the common electrode Y ₁ to Y _n from the terminal O1 to on. This common electrode drive signal is supplied from a bias power supply V supplied from the DC power supply circuit 12.
It is generated based on ₀ ~V _5.

The clock signal cp2 is a clock signal whose period is a period obtained by dividing a period for displaying pixels of one row into several parts, and is output as a clock signal cp2o via the output terminal CP2O of the switching circuit 4 to the segment driving circuit 3. Is input to the clock input terminal XCK.

The display data D _{0 to} D ₃ are supplied to a switching circuit 4.
Display data D ₀ through the output terminal D0O~D3O of o~D
Input terminal XD0-XD of segment drive circuit 3 as ₃ o
3 and sequentially taken into a register in the segment drive circuit 3 in synchronization with the clock signal cp2o. And
When all the display data corresponding to the pixels of one row is captured, the captured display data is latched at the timing of the clock signal cp1o input to the latch pulse input terminal XLP, and the segment corresponding to each display data is obtained. driving pulses of the electrode driving signal is applied from the output terminal of the segment driving circuit 3 O1 to Om to the segment electrode X ₁ to X _m. The segment drive signal is also generated based on the bias power supply V ₀ ~V ₅ supplied from the DC power supply circuit 12.

The inversion signal fr is a signal for periodically inverting the application direction of the voltage applied to the liquid crystal during the display period to prevent the liquid crystal from being deteriorated by electrolysis.
The inverted signal input terminal Y of the common drive circuit 2 is output as the inverted signal fro via the inverted signal output terminal FRO of the switching circuit 4.
FR and inverted signal input terminal XFR of segment drive circuit 3
Entered as

Thus, the pixel matrix of the liquid crystal panel 1 is driven in accordance with the row order by the operation of the common drive circuit 2 and the segment drive circuit 3, and an image corresponding to the display data D _{0 to} D ₃ is displayed on the liquid crystal panel 1. It is done.

On the other hand, during the coordinate detection period, the shift data sd is output from the shift data output terminal Sd of the detection control circuit 6, and the inverted signal f is output from the inverted signal output terminal FRd.
rd is output, the clock signal cp1d is output from the clock output terminal CP1d, the clock signal cp2d is output from the clock output terminal CP2d, and the data output terminals D0d to D0d are output.
Drive data D ₀ d~D ₃ d is output from the 3d.

The clock signal cp1d is a clock signal having a period of a scanning period for scanning one common electrode Y, and is output as a clock signal cp1o via the output terminal CP10 of the switching circuit 4 to the clock input terminal of the common drive circuit 2. YCK and the latch pulse input terminal XLP of the segment drive circuit 3 are input. The shift data sd, which is a pulse signal for selecting a specific common electrode Y, is supplied to the shift data input terminal DIO1 of the common drive circuit 2 as the shift data so via the output terminal SO of the switching circuit 4, and the clock signal cp1d. Input in synchronization with.

Then, as in the above-described display period, the pulse position of the shift data so is shifted by the shift register of the common drive circuit 2 in synchronization with the clock signal cp1o, and the output terminal O1 corresponding to the shift position is shifted.
To the common electrodes Y ₁ to Y _{n from} the common electrode scanning signal y.
₁ ~y _n (hereinafter referred to as y any of the common electrode scanning signal) scan pulse is sequentially applied. The common electrode scanning signal y is generated based on the bias power supply V ₀ ~V ₅ supplied from the DC power supply circuit 12. The above clock signal cp
2d is a clock signal whose cycle is a scanning period for scanning the segment electrode X.
The clock signal cp2o is input to the clock input terminal XCK of the segment drive circuit 3 via P2O.

The drive data D ₀ d to D ₃ d are supplied to the drive data D ₀ o to D ₃ via output terminals D ₀ O to D _{3 O} of the switching circuit 4.
D ₃ o as an input terminal of the segment driving circuit 3 XD0～X
The signal is input to D3, and is sequentially taken into a register in the segment drive circuit 3 in synchronization with the clock signal cp2o. Then, scanning pulses of the segment electrode scanning signals x _{1 to} x _m (hereinafter, an arbitrary segment electrode scanning signal is referred to as x) corresponding to the drive data are output from the output terminals O 1 to Om of the segment driving circuit 3 to the segment electrodes X. is output to ₁ to X _m. The segment electrode scanning signal x is also supplied to the DC power supply circuit 12.
It is generated based on the bias power supply V ₀ ~V ₅ supplied from.

FIG. 11 is a timing chart of each scanning signal in the coordinate detection period of the display-integrated tablet device. The coordinate detection period is the x coordinate detection period followed by y
In the x-coordinate detection period, the segment electrode scanning signal x, which is a pulse voltage signal, is sequentially applied to the segment electrodes X. In the y-coordinate detection period, the common electrode Y, which is a common pulse voltage signal, is applied. Electrode scanning signal y
Are sequentially applied.

By applying the pulse voltage signal, the segment electrode X or the common electrode Y and the designated coordinate detecting pen
A voltage is induced in the detection pen 8 by a stray capacitance between the detection pen 8 (hereinafter, simply referred to as a detection pen) and the tip electrode. The induced voltage generated in the detection pen 8 is amplified by the amplifier 9 and input to the x-coordinate detection circuit 10 and the y-coordinate detection circuit 11.
The x coordinate detection circuit 10 and the y coordinate detection circuit 11
Based on the output signal from the amplifier 9 and the timing signal from the control circuit 7, the time from the application of the pulse voltage signal to the time when the induced voltage reaches the maximum value is detected. Detects the x coordinate or the y coordinate of the position indicated by.

FIG. 12 is a detailed illustration of the inside of the detection pen 8. The detection pen 8 mainly includes a pen tip 15, a detection electrode 16 as the tip electrode, a pen switch 17, and an impedance conversion circuit 18. As described above, in the coordinate detection period, when the scan pulse of the electrode scan signal is applied to the segment electrode X and the common electrode Y (hereinafter, simply referred to as scan electrodes X and Y), the detection electrode 16 and the scan electrode X , Y, the detection electrode 16
, The impedance of the detection electrode 16 is high. The voltage signal induced at the detection electrode 16 is sent to the amplifier 9 (see FIG. 9) via the impedance conversion circuit 18.

The pen tip 15 slides in the axial direction of the detection pen 8, and an inner end thereof is connected to a pen switch 17. This pen switch 17
Has a conductive rubber 19 and terminals 20 and 21;
0 is connected to + 5V, while terminal 21 is connected to ground GND.
It is connected to the.

The detection pen 8 having the above structure operates as follows. That is, when the detection pen 8 is pressed on the liquid crystal panel 1 as a tablet, the pen tip 15 slides inward, and the conductive rubber 19 comes into contact with the terminals 20 and 21 to contact the terminal 2.
The potential of 0 changes from + 5V to the ground level. That is, when the pen switch 17 is turned on, it is detected that the detection pen 8 is positioned on the surface of the liquid crystal panel 1.

[0023]

However, the conventional detecting pen 8 has the following problems. That is, the pen switch 17 is located near the signal line 22 connecting the detection electrode 16 and the impedance conversion circuit 18 and the detection electrode 16. The signal line 22 also has a high impedance.

Therefore, when the pen switch 17 shifts from the "off" state to the "on" state, the pen switch 1
When the voltage of the terminal 21 and the voltage of the switch signal line 23 connected to the terminal 21 change, the detection electrode 16 and the signal located near the terminal 21 and the switch signal line 23 as shown in FIG. An induced voltage is induced on line 22. Since this becomes a noise signal and is erroneously processed as a coordinate detection signal, even if the detection pen 8 is smoothly slid over the liquid crystal panel 1, the detected coordinates become discontinuous, such as so-called “coordinate jump”. There is a problem that it causes false detection.

It is therefore an object of the present invention to provide a coordinate detecting device which can prevent erroneous detection of the coordinates of the tip of a detection pen due to noise caused by a voltage change at the time of turning on / off a pen switch.

[0026]

In order to achieve the above object, the present invention is directed to a panel having a first electrode group and a second electrode group, and a panel for applying a voltage to the first electrode group. 1
A driving circuit, a second driving circuit for applying a voltage to the second electrode group, and a detection pen having a detection electrode at a tip portion electrostatically coupled to the first and second electrode groups, In a coordinate detection device that performs coordinate detection of the detection pen based on a voltage induced in the detection pen by contacting the front end with the panel surface, the detection pen is configured to contact the front end with the panel and A switch that detects or detects non-contact and performs an on / off operation, a low-pass filter provided on a path whose electrical level changes by the on / off operation of the switch, and a process such as amplification of an output signal from the detection electrode. And a path through which the low-pass filter is provided is different from a path from the detection electrode to a signal input unit of the processing circuit.

According to a second aspect of the present invention, there is provided a panel having a first electrode group and a second electrode group, a first driving circuit for applying a voltage to the first electrode group, and a second electrode. A second drive circuit for applying a voltage to the group, and a detection pen having a detection electrode at a tip portion electrostatically coupled to the first and second electrode groups, and contacting the tip portion with the panel surface. In the coordinate detecting device for detecting the coordinates of the detection pen based on the voltage induced on the detection pen, the detection pen detects or detects contact and non-contact of the tip with the panel, and enters or turns off. A switch that operates, a processing circuit that performs processing such as amplification on an output signal from the detection electrode, a path whose electrical level changes when the switch is turned on or off, and a signal input from the detection electrode to the processing circuit. Place provided between the route to the department It is characterized by having a conductivity of voltage.

According to a third aspect of the present invention, there is provided a panel having a first electrode group and a second electrode group, a first drive circuit for applying a voltage to the first electrode group, and a second electrode. A second drive circuit for applying a voltage to the group, and a detection pen having a detection electrode at a tip portion electrostatically coupled to the first and second electrode groups, and contacting the tip portion with the panel surface. In the coordinate detection device that performs the coordinate detection of the detection pen based on the voltage induced on the detection pen, the detection pen has a light-emitting unit and a light-receiving unit, and contacts and contacts the panel at the tip. An optical switch that is turned on or off by blocking or passing light from the light emitting unit to the light receiving unit in response to non-contact, and a processing circuit that performs processing such as amplification on an output signal from the detection electrode. , Electrical level by turning on or off the above switch Varying pathway is characterized by a different route than that from the detection electrode to the signal input of the processing circuit.

According to a fourth aspect of the present invention, there is provided the coordinate detecting device according to the first or third aspect of the present invention, wherein the voltage change time when the switch is turned on or off is 3 ms.
乃至 15 ms.

According to a fifth aspect of the present invention, there is provided a panel having a first electrode group and a second electrode group, a first drive circuit for applying a voltage to the first electrode group, and a second electrode. A second drive circuit for applying a voltage to the group, and a detection pen having a detection electrode at a tip portion electrostatically coupled to the first and second electrode groups, and contacting the tip portion with the panel surface. In the coordinate detecting device for detecting the coordinates of the detecting pen based on the voltage induced on the detecting pen, the detecting pen detects contact and non-contact of the tip with the panel and enters or turns off. And a coordinate rejecting means for rejecting a coordinate at a time point closest to a time when the switch is turned on or off, among coordinates of the detection pen detected by contacting the tip portion with a panel surface. Is characterized by

According to a sixth aspect of the present invention, in the coordinate detecting device of the first to fifth aspects, the panel is a display panel, and the first electrode group and the second electrode group are the display panel. It is also characterized in that it is also used as a display electrode group of a panel, and the first drive circuit and the second drive circuit are also used as a drive circuit of the display panel.

[0032]

In the coordinate detecting device according to the first aspect of the present invention, the tip of the detecting pen is pressed against the panel, and the input by the detecting pen is started. Then, it is detected that the tip is in contact with the panel by turning on or off the switch. At this time, the switch is not turned on by the action of the low-pass filter provided on the path whose electric level changes by turning on or off the switch, instead of the path from the detection electrode to the signal input section of the processing circuit. Alternatively, the level change of the path during the cutting operation becomes gentle. Therefore, noise does not occur in the path from the detection electrode to the processing circuit due to the level change at the time of turning on or off the switch.

In the coordinate detecting device according to the second aspect of the present invention, the tip of the detecting pen is pressed against the panel, and the input by the detecting pen is started. Then, it is detected that the tip is in contact with the panel by turning on or off the switch. An output signal from the detection electrode is supplied to a processing circuit. At this time, the influence of the change in the level on the path in which the electrical level changes when the switch is turned on or off on the path from the detection electrode to the processing circuit depends on the predetermined voltage provided between the two paths. Is shielded by the conductive material. Therefore, noise is not superimposed on the output signal from the detection electrode.

In the coordinate detecting device according to the third aspect of the invention, the tip of the detecting pen is pressed against the panel, and the input by the detecting pen is started. Then, when the tip is pressed against the panel, the light from the light-emitting part to the light-receiving part in the optical switch provided on a path different from the path from the detection electrode to the signal input part of the processing circuit is blocked or It is passed, and the switch is turned on or off, and it is detected that the front end is pressed against the panel. At this time, the operation of turning on or off the switch based on the shielding or passage of light from the light emitting unit to the light receiving unit is performed slowly. Therefore, noise does not occur in the path from the detection electrode to the processing circuit due to the level change at the time of turning on or off the switch.

In the coordinate detecting device according to the fourth aspect of the present invention, the voltage change time at the time of turning on or off the switch is 3 ms to 15 ms. The change in the target level takes place slowly. Therefore, noise does not occur due to a change in the level of the path when the switch is turned on or off.

In the coordinate detecting device according to the fifth aspect of the present invention, the tip of the detecting pen is pressed against the panel, and the input by the detecting pen is started. Then, it is detected that the tip is in contact with the panel by turning on or off the switch. And
The coordinates of the detection pen are detected based on an output signal from the detection electrode to the processing circuit. At this time, the coordinates at the closest point in time when the switch is turned on or off are rejected by the coordinate rejecting means. Therefore, only a coordinate value having a small error which is not affected by noise generated when the switch is turned on or off is output as a detection result.

Further, in the coordinate detecting device according to the sixth aspect of the present invention, it can be integrated with the display panel.

[0038]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. FIG. 1 is a diagram showing the internal structure of a detection pen in the display-integrated tablet device of the first embodiment. Note that the liquid crystal panel, common drive circuit, segment drive circuit, switching circuit, display control circuit, detection control circuit, control circuit, x-coordinate detection circuit, y-coordinate detection circuit, and the like in this embodiment have the same structure as in FIG. doing. In FIG. 1, the detection pen 31 according to the present embodiment mainly includes a pen tip 32, a detection electrode 33, a pen switch 34, and an impedance conversion circuit 35.
And pen switch connecting portion 36 as the force transmitting means
It consists of.

During a coordinate detection period, a scanning pulse is applied to a segment electrode or a common electrode of a liquid crystal panel (not shown) having a tablet function, and detection is performed by a stray capacitance between the segment electrode or the common electrode and the detection electrode 33. In order to induce a voltage on the electrode 33, the impedance of the detection electrode 33 is high. Thus, the voltage signal induced at the detection electrode 33 is transmitted to the impedance conversion circuit 3.
The signal is sent to an amplifier (not shown) through 5 and amplified.

The pen point 32 of the detection pen is configured to slide in the axial direction, and the inner end of the pen point 32 is connected to the pen switch 3 via a pen switch connecting portion 36.
4 is connected. The pen switch 34 has a conductive rubber 37 and terminals 38 and 39.
The terminal 39 is connected to the ground GND.

The detection pen 31 having the above structure operates as follows. That is, when the detection pen 31 is pressed on the liquid crystal panel, the pen tip 32 and the pen switch connecting portion 36
Integrally slide inward to press the conductive rubber 37 against the terminals 38 and 39. Then, the conductive rubber 37 comes into contact with the terminals 38 and 39, and the potential of the terminal 38 changes from + 5V to the ground level. Thus, when the pen switch 34 is turned on, it is detected that the detection pen 31 is positioned on the surface of the liquid crystal panel.

Here, the signal line 40 connecting the detection electrode 33 and the impedance conversion circuit 35 and the detection electrode 33 both have high electrical impedance. However, since both are in a positional relationship apart from the pen switch 34, when the pen switch 34 shifts from the "off" state to the "on" state, the pen switch 3
Even if the voltage of the terminal 38 of No. 4 or the switch signal line 41 connected to this terminal 38 changes, no induced voltage is induced on the detection electrode 33 and the signal line 40.
That is, in the present embodiment, a phenomenon in which the trajectory of the detected pen tip is discontinuous does not appear. That is, erroneous detection such as a so-called jump of coordinates can be prevented.

FIG. 2 is a diagram showing the internal structure of the detection pen according to the second embodiment. The detection pen 51 mainly includes the pen tip 5
2, a detection electrode 53, a pen switch 54, and an impedance conversion circuit 55. Note that also in the present embodiment, the impedance of the detection electrode 53 is high in order to induce a voltage signal on the detection electrode 53.

The pen switch 54 has a conductive rubber 57, terminals 58 and 59, and an RC circuit 56.
While the terminal 59 is connected to the ground GND. The RC circuit 56 is provided at the terminal 58. When the detection pen 51 is pressed onto a liquid crystal panel (not shown) and the conductive rubber 57 contacts the terminals 58, 59, the potential of the terminal 58 changes from + 5V to the ground level. Change is at terminal 5
8 has a gradual change due to the RC circuit 56 provided.

The detection electrode 53 and the signal line 60 are both located near the pen switch 54 and the switch signal line 61, and have high electric impedance. However, as described above, since the voltage change when the pen switch 54 transitions from the “off” state to the “on” state is gradual, an induced voltage may be induced on the detection electrode 53 and the signal line 60. Absent. That is, according to the present embodiment, it is also possible to prevent erroneous detection such as so-called jumping of coordinates, in which the detection coordinates of the tip of the detection pen become discontinuous.

Note that the detection speed of the coordinates of the tip of the detection pen is 6 per second.
In the case of a display-integrated tablet device that is 0 points, the state change of the “ON / OFF” state of the pen switch 54 is 3 ms.
It has been confirmed by the inventor's experiment that no induced voltage is induced in the detection electrode 53 if the time is within 15 ms. Therefore, the respective constants of the RC circuit 56 are R = 470Ω, C = 1
The time of the state change of the pen switch 54 can be set to 4 ms to 5 ms by setting μF.

FIGS. 3 and 4 show the internal structure of the detection pen according to the third embodiment. In FIG. 3, the detection pen 71 mainly includes a pen tip 72, a detection electrode 73, a pen switch 74, an impedance conversion circuit 75, and a conductive sheet 7.
6. The conductive sheet 76 is connected to the ground GND, and includes a signal line 77 and a detection electrode 73 connecting the detection electrode 73 and the impedance conversion circuit 75, and a pen switch 74 and a switch signal line 78.
And so on.

Also in this embodiment, the detection electrode 73 and the signal line 77 are both located near the pen switch 74 and the switch signal line 78, and the impedance of the detection electrode 73 is high. However, a conductive sheet 76 connected to the ground GND is interposed between the detection electrode 73 and the signal line 77 and the like and the pen switch 74 and the switch signal 78 and the like. Therefore, the pen switch 74
The noise generated at the time of “ON / OFF” is cut off, and no induced voltage is induced in the detection electrode 73 and the signal line 77. Therefore, also in this embodiment, it is possible to prevent erroneous detection such as so-called jumping of coordinates.

In this embodiment, as shown in FIG. 4, the same effect can be obtained by using the switch signal line 79 as a shield line and installing the conductive sheet 76 'only in the vicinity of the pen switch 74. .

FIG. 5 is a diagram showing the internal structure of the detection pen according to the fourth embodiment. As shown in FIG.
Reference numeral 1 mainly includes a pen tip 82, a detection electrode 83, a pen switch 84, and an impedance conversion circuit 85.

The pen switch 84 is provided as shown in FIGS.
As shown in FIG. 8, a light shielding plate 86 provided at the rear end of the pen tip
And a light-emitting element 87 and a light-receiving element 88 that are arranged to face each other. The light-receiving element 88 has a voltage change time from the level “L” to the level “H” of about 4 ms.
５5 ms, which is gradual.

When the detection pen 81 is pressed on the liquid crystal panel, the pen tip 82 slides inside and the light shielding plate 8 is moved.
6 is inserted between the light emitting element 87 and the light receiving element 88. Then, the light from the light emitting element 87 is blocked and the terminal voltage of the light receiving element 88 changes. That is, when the pen switch 84 is turned on, it is detected that the detection pen 81 is located on the surface of the liquid crystal panel.

Also in the case of this embodiment, both the detection electrode 83 and the signal line 89 are located near the pen switch 84 and the switch signal line 90, and the electrical impedance is high. However, as described above, since the voltage change when the pen switch 84 shifts from the “off” state to the “on” state is gradual, an induced voltage may be induced on the detection electrode 83 and the signal line 89. Absent. That is,
Also in the present embodiment, it is possible to prevent erroneous detection such as the jump of the coordinates.

In this embodiment, the pen switch 84 is used.
Are composed of a light emitting element 87, a light receiving element 88 and a light shielding plate 86. However, the present invention is not limited to this. The point is that the time required to change the state of the pen switch between "ON / OFF" may be 3 ms to 15 ms as described above.

In the fifth embodiment, the pen switch is turned on when the input by the detection pen is started or ended.
This is an embodiment for rejecting erroneously detected coordinate values caused by noise due to a change in the state of "/ off". FIG. 7 shows the coordinates of the tip of a detection pen when a conventional detection pen is used on a display screen. Point P1 is a point erroneously detected due to a noise component caused by a change in the state of the pen switch from “off” to “on” when the operator presses the detection pen against the liquid crystal panel. Is a group of points correctly detected when the pen switch has not changed its state by continuously tracing the input surface of the liquid crystal panel with the detection pen. This is a point that is erroneously detected due to a noise component when the state changes to “off.” As described above, if all the detected point groups P1 to P8 are used as coordinate values for image display, the actual detection pen Mark and becomes a line containing the line segment shown in different drawing broken lines.

Therefore, in the present embodiment, a jump coordinate detecting section is provided as the detection coordinate selecting means, and the jump coordinate detecting section uses the jump coordinate detecting section as an x coordinate detecting circuit and a y coordinate detecting circuit.
The jump coordinates are detected based on the x-coordinate signal and the y-coordinate signal output from FIG. 9 (see FIG. 9). That is, the jump coordinate detecting unit detects the coordinate value based on the voltage signal from the detection pen at the time point closest to the time point when the pen switch (both not shown) changes the state of “ON / OFF” (points P1, P8) is detected as jump coordinates. Then, the detected jump coordinate value is rejected. As a result, only the coordinate values (points P2 to P7 in FIG. 7) obtained at timings other than the above-mentioned times are output from the jump coordinate detection unit, and as shown by the solid line in FIG. (Displayed with a dashed line).

FIG. 8 is a flowchart of the jump coordinate detection processing operation performed by the jump coordinate detection section and the coordinate display section (not shown). In step S5, F =
In the case of 1 and N = 0, the pen switch has shown the change of state from "off to on" only once, and the detected coordinate value stored in step S4 is the coordinate value of point P1 in FIG. (Jump coordinates). The display of the coordinate values is not performed. On the other hand, when F = 1 and N> 0 in step S5, the pen switches are continuously in the "ON" state, so that points P2 to P2 in FIG.
It is determined that it is the coordinate value of the point P7. And step S
At step 7, the coordinates are displayed.

On the other hand, if the pen switch is "off" in step S6, the pen switch indicates a change from "on to off", and the coordinate values stored in step S4 correspond to the point P8 in FIG. Coordinates (ie jump coordinates)
Is determined to be. Then, the process returns to step S1 to wait for the next input. Thus, the pen switch “ON”
By rejecting erroneously detected coordinate values caused by noise due to the state change of “/ off”, only an image based on only correct detected coordinate values is displayed.

The algorithm of the jump coordinate detection processing in this embodiment is not limited to the above-mentioned algorithm.

[0060]

As is apparent from the above description, the coordinate detecting apparatus according to the first aspect of the present invention prevents noise caused by a change in the electrical level of the path at the time of the on / off operation of the switch. This prevents erroneous detection of the coordinates of the detection pen.

Further, the coordinate detecting device according to the second aspect of the present invention cuts off the influence of a change in the electrical level of the path on the output signal from the detecting electrode when the switch is turned on / off, and the coordinate of the detecting pen is changed. Erroneous detection is prevented.

Further, the coordinate detecting device according to the third aspect of the present invention prevents the occurrence of noise due to a change in the electrical level of the path at the time of the on / off operation of the switch, and prevents erroneous detection of the coordinates of the detecting pen. To prevent. Further, it is not necessary to mount a low-pass filter or a conductive material on the detection pen, and the configuration of the detection pen can be simplified, and the size and weight can be reduced.

Further, the coordinate detecting device according to the fourth aspect of the present invention eliminates the occurrence of noise due to the change in the electrical level of the path when the switch is turned on / off, thereby preventing erroneous detection of the coordinates of the detecting pen. I do.

Further, the coordinate detecting apparatus according to the fifth aspect of the present invention eliminates the influence of the noise on the detected coordinates caused by the change in the electrical level of the path at the time of the switch on / off operation. Prevent erroneous detection.

Further, according to the coordinate detecting apparatus of the invention according to claim 6, in addition to the above effects, the display quality can be improved, the cost can be reduced, and
The size and weight can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an internal structure of a detection pen in a display-integrated tablet device of the present invention.

FIG. 2 is a diagram showing an internal structure of a detection pen different from FIG.

FIG. 3 is a diagram showing an internal structure of a detection pen different from FIGS. 1 and 2;

FIG. 4 is a diagram showing a modification of FIG. 3;

FIG. 5 is a diagram showing an embodiment different from FIGS. 1 to 4;

FIG. 6 is a detailed view of a pen switch in FIG. 5;

FIG. 7 is a diagram illustrating a display example of a detection pen tip coordinate locus.

FIG. 8 is a flowchart of a jump coordinate detection processing operation.

FIG. 9 is a block diagram of a display-integrated tablet device.

10 is a diagram showing an example of a display period and a coordinate detection period in the display-integrated tablet device shown in FIG.

11 is a timing chart of a segment electrode scanning signal and a common electrode scanning signal in the display-integrated tablet device shown in FIG.

FIG. 12 is a diagram showing an internal structure of a conventional detection pen.

13 is an explanatory diagram of stray capacitance and noise generated in each part of the detection pen shown in FIG.

[Explanation of symbols]

31, 51, 71, 81 ... detecting pen, 33, 53, 73, 83 ... detecting electrode, 34, 54, 74, 84 ... pen switch, 35, 55, 75, 85 ... impedance conversion circuit, 36 ... pen switch connection Part, 40, 60, 77, 89 ... signal line, 41, 61, 78, 90 ... switch signal line, 56 ... RC circuit, 76 ... conductive sheet, 79 ... shield wire, 86 ... light shielding plate, 87 ... light emitting element, 88 ... light receiving element.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takao Tagawa 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (72) Inventor Sekitoshi 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka (56) References JP-A-3-294919 (JP, A) JP-A-61-160544 (JP, U) JP-A-1-172139 (JP, U) (58) Fields surveyed (Int. Cl. ⁶ , DB name) G06F 3/03-3/033

Claims (6)

(57) [Claims] 1. A panel having a first electrode group and a second electrode group, a first driving circuit for applying a voltage to the first electrode group, and a second driving circuit for applying a voltage to the second electrode group. Drive circuit,
A detection pen having a detection electrode at a tip portion electrostatically coupled to the first and second electrode groups, wherein the detection pen is brought into contact with the panel surface based on a voltage induced on the detection pen; In the coordinate detecting device for detecting the coordinates of the detection pen, the detection pen detects a contact and a non-contact of the tip portion with the panel and performs an on / off operation, and a switch for on / off operation of the switch. A low-pass filter interposed in a path where the electric level changes; and a processing circuit for performing processing such as amplification on an output signal from the detection electrode. A coordinate detecting device, which is different from a path from an electrode to a signal input section of the processing circuit. 2. A panel having a first electrode group and a second electrode group, a first driving circuit for applying a voltage to the first electrode group, and a second driving circuit for applying a voltage to the second electrode group. Drive circuit,
A detection pen having a detection electrode at a tip portion electrostatically coupled to the first and second electrode groups, wherein the detection pen is brought into contact with the panel surface based on a voltage induced on the detection pen; In the coordinate detecting device for detecting the coordinates of the detecting pen, the detecting pen detects a contact and a non-contact of the tip with the panel to perform an on / off operation, and a switch for detecting an output signal from the detecting electrode. A processing circuit for performing processing such as amplification; a predetermined voltage provided between a path in which an electrical level is changed by turning on or off the switch and a path from the detection electrode to a signal input section of the processing circuit. A coordinate detecting device comprising: a conductive material; 3. A panel having a first electrode group and a second electrode group, a first driving circuit for applying a voltage to the first electrode group, and a second driving circuit for applying a voltage to the second electrode group. Drive circuit,
A detection pen having a detection electrode at a tip portion electrostatically coupled to the first and second electrode groups, wherein the detection pen is brought into contact with the panel surface based on a voltage induced on the detection pen; In the coordinate detection device for detecting the coordinates of the detection pen, the detection pen has a light-emitting unit and a light-receiving unit, and the light-emitting unit moves from the light-emitting unit to the light-receiving unit according to contact and non-contact of the tip with the panel. An optical switch for turning on or off by blocking or passing light; and a processing circuit for performing processing such as amplification on an output signal from the detection electrode. The path in which the path changes is different from the path from the detection electrode to the signal input section of the processing circuit. 4. The coordinate detecting device according to claim 1, wherein the voltage change time at the time of turning on or off the switch is 3 ms to 15 ms. 5. A panel having a first electrode group and a second electrode group, a first driving circuit for applying a voltage to the first electrode group, and a second driving circuit for applying a voltage to the second electrode group. Drive circuit,
A detection pen having a detection electrode at a tip portion electrostatically coupled to the first and second electrode groups, wherein the detection pen is brought into contact with the panel surface based on a voltage induced on the detection pen; In the coordinate detection device for detecting the coordinates of the detection pen, the detection pen has a switch that performs an on / off operation by detecting contact and non-contact of the tip with the panel, and the tip has a panel surface. A coordinate rejecting means for rejecting coordinates closest to a point in time when the switch is turned on or off, among coordinates of the detection pen detected by contacting the touch panel. 6. The coordinate detecting device according to claim 1, wherein the panel is a display panel, and the first electrode group and the second electrode group are also used as a display electrode group of the display panel. And a first drive circuit and a second drive circuit which are also used as drive circuits for the display panel.