JP2974536B2 - Tablet 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 tablet device used for a personal computer or a word processor.

[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 which eliminates such a drawback, a display-integrated tablet device as shown in FIGS. 7 and 8 has recently been proposed (Japanese Patent Application No. Hei 4-19).
No. 064 and Japanese Patent Application No. 4-320545). 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. As shown in FIG. 9, 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.

FIG. 7 shows a duty type liquid crystal panel 1.
Is a display-integrated tablet device. In FIG. 7, a liquid crystal panel 1 includes n common electrodes Y _{1 to} Y _n (hereinafter, an arbitrary common electrode is described as Y) and m segment electrodes X _{1 to} X _m (hereinafter, referred to as Y) arranged orthogonal to each other. Hereinafter, an arbitrary segment electrode is referred to as X), and a liquid crystal is interposed between the common electrode Y and the segment electrode X.
Each pixel is constituted by a region where. That is, pixels of n × m dots are arranged in a matrix on the liquid crystal panel 1.

In this display-integrated tablet device,
During the display period, various display control signals from the display control circuit 5 are selected by the switching circuit 4 and supplied to the common drive circuit 2 and the segment drive circuit 3. Then, a drive pulse of a common electrode drive signal is applied to the common electrode Y by the common drive circuit 2. On the other hand, a drive pulse of a segment electrode drive signal is applied to the segment electrode X by the segment drive circuit 3. During the coordinate detection period, the switching control circuit 4 controls the detection control circuit 6.
Various detection control signals are selected from the common drive circuit 2
And supplied to the segment drive circuit 3. Then, the common electrode scanning signal y ₁ ~y _n (hereinafter, an arbitrary common electrode scanning signal to as y) to the common electrode Y ₁ to Y _n by the common drive circuit 2 scan pulse is sequentially applied. on the other hand,
The segment electrodes X _{1 to} X _m by the segment driving circuit 3
, Scanning pulses of the segment electrode scanning signals x _{1 to} x _n (hereinafter, an arbitrary segment electrode scanning signal is referred to as x) are sequentially applied.

As shown in FIG. 9, the coordinate detection period is x
It is divided into a coordinate detection period and a subsequent y-coordinate detection period. In the x-coordinate detection period, the scanning pulse of the segment electrode scanning signal x is sequentially applied to the segment electrodes X, while the common pulse is applied to the common electrode Y in the y-coordinate detection period. The scanning pulse of the electrode scanning signal y is sequentially applied. At that time, due to the application of the scanning pulse, the segment electrode X or the common electrode Y and the designated coordinate detecting pen (hereinafter simply referred to as detecting pen) 8
A voltage is induced in the detecting pen 8 by the stray capacitance between the detecting pen 8 and the detecting electrode. Therefore, the x-coordinate detecting circuit 10 and the y-coordinate detecting circuit 11 respectively detect the pen 8 based on the induced voltage signal obtained by amplifying the induced voltage generated in the detecting pen 8 by the amplifier 9 and the timing signal from the control circuit 7. The x coordinate or y coordinate of the designated position is detected.

FIG. 8 shows a display integrated tablet device having an active matrix type liquid crystal panel 21. In the liquid crystal panel 21, n of gate bus line electrodes G ₁ ~G _n (hereinafter, an arbitrary gate bus line electrode to as G) and m source bus line electrodes S ₁ to S _m
(Hereinafter, an arbitrary source bus line electrode is described as S)
Are arranged orthogonally and insulated from each other, and at the intersection of the gate bus line electrode G and the source bus line S, T
An FT (thin film transistor) 25 is disposed, and the TFT 2
The pixel is composed of a pixel electrode 24 connected to the pixel electrode 5, a counter electrode (not shown) facing the pixel electrode 24, and a liquid crystal filled between the two electrodes. That is, the liquid crystal panel 21
, Display pixels of n × m dots are arranged in a matrix.

During the coordinate detection period, the detection pen 8 is positioned on the input surface of the liquid crystal panel 21 as in the case of the display-integrated tablet device having the duty type liquid crystal panel 1 described above. A voltage induced on the detection electrode of the detection pen 8 by electrostatic coupling between the detection electrode and the gate bus line electrode G or the source bus line electrode S is detected, and the x-coordinate detection circuit 10 or the y-coordinate detection circuit 11 detects the voltage. 8 are obtained.

Therefore, in a display-integrated tablet device having the duty type liquid crystal panel 1 and the active matrix type liquid crystal panel 21, when characters or figures are input to the liquid crystal panel 1 or the liquid crystal panel 21, the detection is performed. The pen 8 is slid with the pen 8 in contact with the input surface of the liquid crystal panel 1 or the liquid crystal panel 21 to obtain the tip coordinates of the detection pen 8 based on the induced voltage signal detected by the detection pen 8, and the position of the tip coordinates When the display control circuit 5 outputs display data for displaying a point on the liquid crystal panel 1, the trajectory of the tip of the detection pen 8 is displayed.
Alternatively, it can be displayed on the liquid crystal panel 21.

At this time, as shown in FIG. 10, the tip of the detection pen 8 is connected to the liquid crystal panel 1 or the liquid crystal panel 21.
The input surface of the protection panel 31 is coated with an insulating resin 33 so that the input surface of the protection panel 31 is not scratched and damaged by the detection electrode 32.

[0011]

However, the display-integrated tablet device having the conventional duty type liquid crystal panel 1 and active matrix type liquid crystal panel 21 has the following problems.

That is, in the coordinate detection period,
A scanning pulse of an electrode scanning signal is alternately applied to the segment electrode X or the source bus line electrode S and the common electrode Y or the gate bus line electrode G, and based on the scanning pulse, the input impedance set at the tip of the detection pen 8 A voltage is induced on the detection electrode 32 having a higher height, and the tip coordinates of the detection pen 8 are detected based on the timing of generation of the induced voltage.

However, the detection electrode 32 of the detection pen 8
Is very weak. In particular, in the case of a display-integrated tablet device having a duty-type liquid crystal panel 1 as shown in FIG.
The electric field generated by the lower electrode (segment electrode X in FIG. 7) of the common electrode Y causes an upper electrode (FIG. 7).
In the case of the above, since the lower electrode is shielded by the common electrode Y), when scanning the lower electrode, it is necessary to detect a leakage electric field through a small gap between the upper electrode and the lower electrode. In this case, the induced voltage is as small as several mV.

In the case of a display-integrated tablet device having an active matrix type liquid crystal panel 21 shown in FIG. 8, a source bus line electrode S for driving the TFT 25 and a gate bus line electrode G are used as scanning electrodes. However, since the width of each of the source bus line electrode S and the gate bus line electrode G is several tens of microns, the induced voltage detected by the detection electrode of the detection pen 8 is extremely weak.

As described above, in the display-integrated tablet device having the duty-type liquid crystal panel 1 and the display-integrated tablet device having the active matrix type liquid crystal panel 21, the detection electrode 32 of the detection pen 8 is used during the coordinate detection period. The induced voltage is very weak. Therefore, it is very susceptible to external noise. There are various noise sources. One of them is the tip of the detection pen 8 when the detection pen 8 slides on the surface of the protection panel 31 of the liquid crystal panel 1 or the liquid crystal panel 21 to write a character or a figure. Tip resin 33 covering
There is noise due to frictional electrification between the power supply and the protection panel 31. The triboelectric charge is applied to the tip resin (dielectric) 3 of the detection pen 8.
Noise due to frictional charging between the tip resin 33 and the protection panel 1 does not pose a problem under normal conditions because the noise is gradually attenuated by the leakage current of the protection panel 3 and the protection panel 31.

However, when the display-integrated tablet device is installed in an environment where the humidity is abnormally low, the resistance of the dielectric material, which is the tip resin 33 of the detection pen 8, increases.
When the voltage generated by the frictional charging exceeds the attenuation, the frictional charging voltage increases, and when the voltage exceeds the limit value, discharge is instantaneously generated in a portion having a small charge amount. At this time, since the voltage of the charged portion is instantaneously greatly changed by the discharge, a spike-like noise voltage is induced on the detection electrode 32 of the detection pen 8 and is input to the coordinate detection circuits 10 and 11 as an erroneous detection signal. .

Further, when an electric appliance which operates at a relatively high frequency and a high voltage, which is extremely rare, is brought close to the input surface of the liquid crystal panel 1 or the liquid crystal panel 21, the voltage from the electric appliance is detected. The detection electrode 32 of the pen 8 detects the noise as noise, which adversely affects the detection of the tip coordinates of the detection pen 8.

FIG. 11 shows an induced voltage induced on the detection electrode 32 of the detection pen 8 when the lower segment electrode X is scanned in the x coordinate detection period in the duty type liquid crystal panel 1 shown in FIG. And a waveform without external noise. FIG. 11 (b)
Is a binary signal of the induced voltage obtained by binarizing slice voltage "e _s" by a comparator having a waveform as shown in FIG. 11 (a). In this case, if the number of scans in the x-coordinate detection period is only one, the binarized signal based on the induced voltage induced on the detection electrode 32 of the detection pen 8 as shown in FIG. One pulse is generated.

However, when the detection electrode 32 of the detection pen 8 detects external noise during the x coordinate detection period,
Even if the segment electrode X is scanned only once, a plurality of pulses are generated in the binary signal. Therefore, an x-coordinate signal representing a coordinate different from the true tip coordinate of the detection pen 8 detected by the x-coordinate detection circuit 10 based on a pulse caused by external noise is also output. Therefore, when a character or a figure is input to the liquid crystal panel 1 or the liquid crystal panel 21, the liquid crystal panel 1 or the liquid crystal panel 21 is located at a position where the tip of the detection pen 8 does not pass in addition to the trajectory of the tip of the detection pen 8. An image resulting from external noise will be erroneously displayed.

An object of the present invention is to provide a tablet device capable of stably and accurately detecting the tip coordinates of a detection pen even when external noise is detected by the detection pen during a coordinate detection period.

[0021]

In order to achieve the above object, a first invention is directed to a first electrode group arranged in one direction and a second electrode group arranged in another direction orthogonal to the one direction. A detection pen having at its tip a detection electrode electrostatically coupled to a first electrode group and a second electrode group of the panel; a first drive circuit for driving the first electrode group; A second drive circuit for driving the second electrode group; and a detection circuit for controlling the first drive circuit and the second drive circuit during the coordinate detection period to sequentially apply a scanning voltage to the first electrode group or the second electrode group. A control circuit; and a coordinate detection circuit for detecting coordinates on the panel indicated by the tip of the detection pen from the generation timing of the output signal from the detection pen and the scanning timing of the first electrode group or the second electrode group. In the tablet device, the seat Counting means for counting the number of times that an output signal output from the detection pen exceeds a threshold value in a detection period; and counting by the counting means during one coordinate detection period and the detection control during one coordinate detection period. The number of scans of the electrode group by the circuit is compared, and if the count is larger than the number of scans, the coordinates on the panel detected by the coordinate detection circuit during the coordinate detection period include erroneously detected coordinates. It is characterized by including an erroneous detection determination means for determining that the data is included.

[0022]

According to a second aspect of the present invention, there is provided a panel having a first electrode group arranged in one direction and a second electrode group arranged in another direction orthogonal to the one direction, and a first electrode of the panel. A detection pen having a detection electrode electrostatically coupled to the group and the second electrode group at a tip thereof; and a first pen for driving the first electrode group.
A drive circuit, a second drive circuit for driving the second electrode group,
A detection control circuit for controlling the first drive circuit and the second drive circuit during the coordinate detection period to sequentially apply a scanning voltage to the first electrode group or the second electrode group; and generating an output signal from the detection pen. A tablet device having a coordinate detection circuit for detecting coordinates on a panel indicated by the tip of the detection pen from timing and scanning timing of the first electrode group or the second electrode group. A binary signal that is binarized at a different slice level between the one slice level and a second slice level higher than the first slice level and is binarized at the first slice level is sent to the coordinate detection circuit. The binarizing means monitors the binarized signal binarized by the binarizing means at the second slice level, and the level of the binarized signal exceeds a threshold. In such a case, there is provided an erroneous detection determination unit that determines that the coordinates on the panel detected by the coordinate detection circuit at the time closest to the time when the threshold value is exceeded are erroneously detected coordinates. .

[0024]

[0025]

According to the first aspect of the present invention, in the coordinate detection period, the first drive circuit and the second drive circuit are controlled by the detection control circuit, and the scanning voltage is sequentially applied to the first electrode group or the second electrode group of the panel. You. Then, a voltage is induced on the detection electrode of the detection pen due to the scanning voltage applied to the first electrode group or the second electrode group, and a signal based on the induced voltage is output from the detection pen. Then, the number of times that the output signal from the detection pen exceeds the threshold value is counted by the counting means.

Further, based on the count result by the counting means, the erroneous detection judging means scans the number of electrodes during one coordinate detection period and scans the electrode group by the detection control circuit during one coordinate detection period. When the number of times is compared with the number of times, and the count number is larger than the number of times of scanning, it is determined that the coordinates on the panel detected by the coordinate detection circuit during the coordinate detection period include erroneously detected coordinates. Is determined.

When the erroneous detection determining means determines that the erroneously detected coordinates are included in the above-described manner, by taking measures such as rejecting the coordinate values detected during the coordinate detection period, the erroneous detection is performed. Even if external noise is detected by the pen, the tip coordinates of the detection pen can be detected stably and accurately.

[0028]

[0029]

In the second invention, in the coordinate detection period, the output signal from the detection pen is converted into a different slice between a first slice level and a second slice level higher than the first slice level by the binarizing means. 2 at level
Valued. Then, the binarized signal binarized at the first slice level is sent to the coordinate detection circuit. on the other hand,
The binarized signal binarized at the second slice level is monitored by an erroneous detection determination unit. When the level of the binarized signal exceeds the threshold value, the erroneous detection determining means detects the coordinates on the panel detected by the coordinate detection circuit at the time when it approaches the time point when the threshold value is exceeded. Are determined to be erroneously detected coordinates.

[0031]

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. The basic structure of the tablet device in this embodiment is the same as that of the display integrated tablet device having the duty type liquid crystal panel 1 shown in FIG. 7 or the display integrated tablet device having the active matrix type liquid crystal panel 21 shown in FIG. is there. Therefore, in the following description of each embodiment, the numbers in FIGS. 7, 8 and 10 are used as needed.

<First Embodiment> FIG. 1 shows a coordinate detection period by a display integrated tablet device having a duty type liquid crystal panel 1 or a display integrated tablet device having an active matrix type liquid crystal panel 21 in this embodiment. 5 shows a waveform of the induced voltage induced on the detection electrode 32 of the detection pen 8. FIG. 1A shows an external voltage following a normal induced voltage signal (hereinafter referred to as a normal detection signal) caused by a scanning pulse of the segment electrode scanning signal x or the source bus line electrode scanning signal during the x coordinate detection period. Induction voltage signal caused by noise (hereinafter referred to as erroneous detection signal)
5 shows a waveform in the case where has occurred. Also, FIG.
is a binary signal obtained by binarizing slice voltage "e _s" in the comparator after amplifying the induced voltage shown in (a) by the amplifier 9.

Whether or not the erroneous detection signal caused by external noise is included in the induced voltage signal induced in the detection electrode 32 of the detection pen 8 is determined by the above during the x coordinate detection period or the y coordinate detection period. The determination can be made by counting the number of pulses present in the binary signal from the comparator.

Therefore, in this embodiment, the x-coordinate detecting circuit 10 and the y-coordinate detecting circuit 11 are provided with a counting means and a comparing means, so that the induction detected by the detecting electrode 32 during the x-coordinate detecting period or the y-coordinate detecting period. The number of pulses of the binary signal based on the voltage signal is counted by the counting means. Then, the comparing means compares the count result of the counting means with the preset number of electrode scans in the x-coordinate detection period and y-coordinate detection period. It outputs a detection alarm signal.
For example, in the case of FIG. 1, since one false detection signal is included in addition to the normal detection signal as shown in FIG. 1A, two pulses are generated as shown in FIG. 1B. Then, it is immediately found that the detection is erroneous.

In other words, the comparing means constitutes the erroneous detection judging means.

In this case, the erroneous coordinates (hereinafter referred to as erroneous detection coordinates) due to the erroneous detection signal being included in the induced voltage signal detected by the detection electrode 32 are obtained when the level of the normal detection signal is low. The scanning of the lower electrode (segment electrode X in the display-integrated tablet device having the duty-type liquid crystal panel 1 in this embodiment) is mainly performed, and the scanning period of the upper electrode (the y-coordinate in this embodiment). During the detection period, the level of the normal detection signal is high, so that erroneous detection coordinates are hardly obtained. Therefore, the counting means and the comparing means are provided only in the coordinate detection circuit relating to the scanning of the lower electrode of the x-coordinate detection circuit 10 and the y-coordinate detection circuit 11, and the erroneous detection coordinates are obtained only when the lower electrode is scanned. May be determined.

As described above, the erroneous detection warning signal output from the warning means is taken into processing means such as a microprocessor. The processing means invalidates the x-coordinate signal and the y-coordinate signal output from the x-coordinate detection circuit 10 and the y-coordinate detection circuit 11 during the coordinate detection period in which the erroneous detection alarm signal is generated. At that time,
The tip coordinate value of the detection pen 8 is rejected despite the detection of the normal detection signal, so that the tip
(That is, characters and figures) become unnatural. Therefore, the coordinate value in the previous coordinate detection period is used as the coordinate value in the current coordinate detection period, or the coordinate of the middle point between the coordinate value in the previous coordinate detection period and the coordinate value in the next coordinate detection period is set as the current coordinate. By using the coordinate values in the detection period, the above-described unnaturalness can be prevented.

As described above, when the false detection warning signal is generated, the x-coordinate detection circuit 10
If all the coordinate signals output from the y-coordinate detection circuit 11 are invalidated, not only the coordinate signal based on the erroneous detection signal but also the coordinate signal based on the normal detection signal are invalidated.

Therefore, even if the erroneous detection warning signal is output, the accuracy of detecting the tip coordinates of the detection pen 8 can be further improved by obtaining a regular coordinate value as follows. That is, the currently calculated tip coordinate value of the detection pen 8 is compared with the tip coordinate value calculated immediately before by the processing means to determine whether or not the currently calculated coordinate value is an erroneously detected coordinate value. judge. Then, only when it is determined that the coordinate value is an erroneously detected coordinate value, the tip coordinate value is rejected. By doing so, the tip coordinates of the detection pen 8 can always be calculated based on the regular detection signal, and the coordinate detection accuracy can be improved.

As described above, an erroneous detection signal superimposed on the induced voltage signal from the detection pen 8 often produces an incorrect coordinate value when the lower electrode is scanned. Is rare when the upper electrode is scanned. Therefore, for example, as shown in FIG. 7, when the segment electrode X is the lower electrode, the x-coordinate detection circuit 1
Various processes as described above may be performed only on the x coordinate signal from 0, and the y coordinate signal from the y coordinate detection circuit 11 may be output as it is.

<Second Embodiment> As shown in FIG. 2, the detection control circuit 6 of the display-integrated tablet device according to the present embodiment operates between the x coordinate detection period and the y coordinate detection period of the coordinate detection period. It operates to provide a noise detection period. In FIG. 2, the noise detection period is set immediately after the x coordinate detection period. However, in order to avoid the influence of the scanning of the segment electrode X, a number of noise detection periods are actually set between the x coordinate detection period and the noise detection period. A period of about 10 microseconds is set.

During the noise detection period, the scanning pulse of the electrode scanning signal is not applied to either the segment electrode X or the common electrode Y. Therefore, only a DC voltage is applied to the segment electrode X and the common electrode Y during the noise detection period, and no induced voltage is generated at the tip electrode 31 of the detection pen 8. The output voltage is “0V”. However, when the detection pen 8 receives AC noise from outside,
As shown in FIG. 2, the induced voltage signal is output from the detection pen 8 even in the noise detection period. Therefore,
If the induced voltage signal is detected in spite of the noise detection period, it is highly likely that the x-coordinate detection period or the y-coordinate detection period is also affected by the noise.

Therefore, a full-wave rectifier and a comparator are provided, and the induced voltage from the detection pen 8 during the noise detection period is smoothed after full-wave rectification by the full-wave rectifier. Is compared with the reference voltage, and if the rectified voltage exceeds the reference voltage, it is determined that the influence of noise also exists in the x-coordinate detection period and the y-coordinate detection period. Alternatively, the induced voltage from the detection pen 8 during the noise detection period is amplified by the amplifier 9 and then binarized by the comparator. When a pulse is detected in the binarized signal by the pulse detection means, the x-coordinate detection period and the It is determined that the influence of noise is also present in the y coordinate detection period.

That is, in this embodiment, the erroneous detection determining means is constituted by the full-wave rectifier and the comparing means, or the comparator and the pulse detecting means.

In this way, when it is determined that the influence of noise is also present in the x-coordinate detection period and the y-coordinate detection period, the warning means outputs an erroneous detection warning signal to the processing means. Thereafter, if the same processing as in the first embodiment is performed by the processing means, correct tip coordinates can be obtained even if the detection electrode 32 of the detection pen 8 detects noise.

<Third Embodiment> The level of the induced voltage induced in the detection electrode 32 due to the friction between the tip resin 33 of the detection pen 8 and the protection panel 31 of the liquid crystal panels 1 and 21 as shown in FIG. Is extremely large. Therefore, in the present embodiment, as shown in FIG. 3, the induced voltage from the detection pen 8 is binarized by two comparators 41 and 42 having different reference voltages of the first comparator 41 and the second comparator 42. . The first comparator 41 is for detecting an x coordinate, and is the same as a conventionally used comparator for detecting an x coordinate (omitted in FIGS. 7 and 8). On the other hand, the second comparator 42 is a noise detection comparator. Here, the first comparator 41
Of the reference voltage and "e _s", when the "e _n" the reference voltage of the second comparator, the relationship between the two reference voltage "e _s" and _{"e n", e s <} e max <e n e _mak : the peak value of the normal detection signal induced on the detection electrode 32.

Although the above-described configuration has been described by taking as an example the processing for the induced voltage signal input to the x coordinate detection circuit 10, y
The coordinate detection circuit 11 has a similar configuration.

The induced voltage output from the detection electrode 32 during the x-coordinate detection period and input to the first comparator 41 and the second comparator 42 has a waveform as shown in FIG. And As a result, the first comparator 41 outputs the binarized signal of FIG. 1 using the slice voltage “ _es ”.
A binary signal having two pulses (a pulse based on the normal detection signal and the erroneous detection signal) as shown in (b) is output. On the other hand, the binary signal is output with a (pulse based on erroneous detection signal) one pulse as shown in FIG. 1, which is binarized by the slice voltage "e _n" (c) from the second comparator 42 .

Therefore, the x coordinate detection circuit 10 and y
A pulse detecting means and an alarming means are provided in the coordinate detecting circuit 11, and the pulse detecting means makes the second comparator 4
The second comparator 42 monitors the binarized signal from
When a pulse is detected in the binarized signal from, a false detection alarm signal is output to the processing means. In addition, the first
Paying attention to the fact that a pulse based on the erroneous detection signal exists in both of the binarized signal from the comparator 41 and the binarized signal from the second comparator 42, the x-coordinate detection circuits 10 and y A subtraction means is provided in the coordinate detection circuit 11,
By subtracting the binarized signal from the second comparator 42 from the binarized signal from the first comparator 41 by the subtraction means, only a pulse based on the normal detection signal can be obtained.

That is, in the present embodiment, the first
The comparator 41 and the second comparator 42 set the above 2
The pulse detecting means constitutes the erroneous detection judging means.

<Fourth Embodiment> In this embodiment, during the coordinate detection period, the x-coordinate signal sequentially output from the x-coordinate detection circuit 10 and the y-coordinate detection circuit 11 of the display-integrated tablet device are sequentially output. The erroneous detection coordinates are detected from the mutual positions of the coordinates of the tip of the detection pen 8 based on the y coordinate signal.

[0053] Figure 4, the distance L _n between the x-coordinate signal and the two coordinate points tip coordinate point P _n and adjacent y-coordinate signal detection was calculated based on the pen 8 P _n-1, P _n Show.
In this case, the distances between the coordinate points,..., L _n−1 , L _n , L _{n + 1} ,... Are determined by the writing speed of the operator. There is no sharp change. However, as shown in FIG. 4, the distance to the erroneous detection coordinate point P 'false If _n jump detection coordinate point _{P' n L 'n, L} ' n + 1 distance is normal L _n, the L _{n + 1} In comparison, the distance becomes abnormally large and becomes a distance that cannot be artificially changed.

[0054] Therefore, by monitoring the distance L _n between the coordinate points which are sequentially detected in the coordinate detection period, it can be removed as erroneously detected coordinates artificially unrealizable coordinate point P _'n.

As such a method, there is the following method. That is, the processing means determines the coordinates (x _n , x _n ) of the point P _n indicated by the tip of the detection pen 8 based on the x coordinate signal from the x coordinate detection circuit 10 and the y coordinate signal from the y coordinate detection circuit 11. y _n) is calculated. And further, the point _{P n (x n, y n} ) and the immediately preceding detection point P _n-1 of the coordinates (x _n-1, y
calculates the distance L _n from _n-1) and, when the value of the distance L _n exceeds a comparison value L _max, it is to remove as detected coordinates coordinates (x _n of the point P _n, the y _n) erroneously.

That is, the processing means constitutes the distance calculation means and the erroneous detection determination means.

At this time, if the comparison value _Lmax is selected to be large, the erroneously detected coordinates can be reliably removed, but cannot be removed when L' _n is about 15 mm. On the other hand, the comparison value L
_{If max is set} to about 15 mm, erroneous detection coordinates can be removed when L' _n is about 15 mm, but normal detection coordinates may also be removed. Hereinafter, a method for addressing such a problem will be described.

[0058] Figure 5 is a diagram showing an example of a tip trace detection pen 8 in the case where the distance L _n to the writing speed by the detection pen 8 is fast exceeds 20 mm. Although such a tip trajectory is rare at the time of character input, it is often seen in handwriting when performing graphic input or gesture operation. Therefore, the input mode is divided into a character input mode and a graphic input mode. In the character input mode, the value of L _max is reduced, and in the graphic input mode, the value of L _max is increased. By doing so, the erroneously detected coordinates can be correctly removed according to the writing speed.

The following example is an example of obtaining a writing speed ratio.
Figure 6 shows the speed ratio L _n / L _{n + 1} at the time of writing by detecting pen 8 as determined by several operators. In FIG. 6, in the case of low-speed writing where the writing speed is lower than 5 mm / sec,
Speed ratio L _n / L _{n + 1} is distributed widely. However,
When writing speed is 5 mm / sec or faster writing the speed ratio L _n / L _{n + 1} is within the range of approximately 0.7 to 1.3.
Therefore, the value of the distance L _n calculated by the processing means on the basis of the two coordinate points P _n-1, the coordinates of P _n is monitored by the processing means, slow in the low speed writing than writing speed 5 mm / sec In some cases, the calculated tip coordinate value of the detection pen 8 is adopted as it is. On the other hand, if the writing speed is the high speed writing is 5 mm / sec or more, and calculates the speed ratio L _n / L _{n + 1} by the processing means, the value of the speed ratio L _n / L _{n + 1} is If it is outside the maximum value of the distribution range shown in FIG. 6, the obtained tip coordinate value is rejected.

[0060] In the example described above, both, and detects the detected coordinates erroneous in view of the value of the movement distance L _n per unit time of the tip position of the detection pen 8. However, as described above, in the case of a display-integrated tablet device having the duty-type liquid crystal panel 1, the detection electrode 32 of the detection pen 8 actually detects an erroneous detection signal only when the liquid crystal panel 1 is used.
Is mainly the case where the lower electrode (in this embodiment, the segment electrode X) is scanned. Therefore,
In the detection of the erroneous detection coordinates, it is not always necessary to use the moving distance L _n per unit time of the tip position of the detection pen 8 as described above, only the moving distance in units of the x-coordinate value of the tip of the detection pen 8 hours You can pay attention.

[0061] In the above-described fourth embodiment, the distal end coordinate point P ₁ in FIG. _{4, P 2, ... P n} -1, P n, ..., although the effective coordinates the coordinates of P _z, 2 points P _1, middle point P _'1 of P _{2, 2} points P _2, P ₃
The coordinates of the midpoint P ′ ₂ ,... May be used as the effective coordinates. Also,
As the active matrix used in the liquid crystal panel 21 in each of the above-described embodiments, an active matrix based on a TFT method is described as an example. However, the active matrix of the present invention is not limited to this, and may be, for example, a diode type active matrix, a MIM (metal-insulator-metal) type active matrix, a varistor type active matrix, or the like. .

[0062]

As is clear from the above, the tablet device of the first invention counts the number of times that the output signal from the detection pen exceeds the threshold value during the coordinate detection period by the counting means, and the erroneous detection determining means counts one. If it is detected that the number of counts by the counting means during one coordinate detection period is greater than the number of times of scanning of the electrode group by the detection control circuit during one coordinate detection period, the erroneous detection determination means determines Since it is determined that the coordinates on the panel detected by the coordinate detection circuit during the detection period include erroneously detected coordinates, it is possible to detect that the detection pen has detected external noise.

Therefore, for example, when the erroneous detection determining means determines that the erroneously detected coordinates are included, if measures such as rejecting the coordinates on the panel obtained during the coordinate detection period are taken, the coordinates can be reduced. Even if the detection pen detects external noise during the detection period, the tip coordinates of the detection pen can be detected stably and accurately.

[0064]

[0065]

In the tablet device according to the second aspect of the present invention, in the coordinate detection period, the binarizing means converts the output signal from the detection pen into a first slice level and a second slice level higher than the first slice level. A binary signal that has been binarized at different slice levels and binarized at the first slice level is sent to a coordinate detection circuit, and erroneous detection determination means determines that the binarization signal is binary at the second slice level. When it is detected that the level of the binarized binary signal exceeds the threshold, the erroneous detection determining means detects the position on the panel detected by the coordinate detection circuit at the time closest to the time when the level exceeds the threshold. Are determined to be erroneously detected coordinates, it can be detected that the detection pen has detected external noise.

Therefore, according to the present invention, even when the detection pen detects external noise during the coordinate detection period, the tip coordinates of the detection pen can be detected stably and accurately.

[0068]

[0069]

[Brief description of the drawings]

FIG. 1 is a diagram showing an induced voltage signal including an erroneous detection signal induced by a detection pen in a tablet device of the present invention, and a binarized signal obtained by binarizing the induced voltage signal with different slice voltages.

FIG. 2 is a diagram illustrating an example of an induced voltage signal and a binarized signal of the induced voltage signal when a noise detection period is provided in a coordinate detection period.

FIG. 3 is an explanatory diagram of a configuration for obtaining a binarized signal binarized by different slice voltages as shown in FIG. 1;

FIG. 4 is an explanatory diagram of a method of detecting erroneously detected coordinates based on a calculated distance between tip coordinate points.

FIG. 5 is a diagram showing an example of a tip trajectory of a detection pen.

FIG. 6 is a diagram showing a distribution state of a writing speed ratio L _n / L _{n + 1} by a detection pen.

FIG. 7 is a block diagram of a display-integrated tablet device having a duty-type liquid crystal panel.

FIG. 8 is a block diagram of a display integrated tablet device having an active matrix type liquid crystal panel.

9 is an explanatory diagram of a display period and a coordinate detection period in the display-integrated tablet device shown in FIGS. 7 and 8. FIG.

FIG. 10 is a detailed view of the tip of the detection pen in FIGS. 7 and 8;

FIG. 11 is a diagram showing a normal induced voltage signal induced on the detection electrode of the detection pen in FIGS. 7 and 8, and a binarized signal based on the induced voltage signal.

[Explanation of symbols]

1, 21: liquid crystal panel, 2: common drive circuit, 3: segment drive circuit, 8: detection pen, 10: x coordinate detection circuit, 11: y coordinate detection circuit, 22: gate drive circuit, 23 ...
Source drive circuit, 31 ... Protection panel,
32: detection electrode, 33: tip resin,
41: first comparator, 42: second comparator.

Continuation of the front page (72) Inventor Kazunari Okamura 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-5-53726 (JP, A) JP-A-5-80921 ( JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) G06F 3/03 G06F 3/033 H03K 5/01

Claims (2)

(57) [Claims] 1. A panel having a first electrode group arranged in one direction and a second electrode group arranged in another direction orthogonal to the one direction, and a first electrode group and a second electrode group of the panel. A detection pen having a detection electrode at its tip electrostatically coupled to the first electrode group; a first drive circuit for driving the first electrode group; a second drive circuit for driving the second electrode group; A detection control circuit for controlling the first drive circuit and the second drive circuit to sequentially apply a scanning voltage to the first electrode group or the second electrode group; a generation timing of an output signal from the detection pen; In a tablet device having a coordinate detection circuit for detecting coordinates on a panel indicated by the tip of the detection pen from the scanning timing of the first electrode group or the second electrode group, an output output from the detection pen during the coordinate detection period Faith Counting means for counting the number of times that exceeds a threshold value, and comparing the number of counts by the counting means during one coordinate detection period with the number of scans of the electrode group by the detection control circuit during one coordinate detection period, If the count number is larger than the number of scans, an erroneous detection determination unit that determines that the coordinates on the panel detected by the coordinate detection circuit during the coordinate detection period include erroneously detected coordinates. A tablet device comprising: 2. A panel having a first electrode group arranged in one direction and a second electrode group arranged in another direction orthogonal to the one direction, and a first electrode group and a second electrode group of the panel. A detection pen having a detection electrode at its tip electrostatically coupled to the first electrode group; a first drive circuit for driving the first electrode group; a second drive circuit for driving the second electrode group; A detection control circuit for controlling the first drive circuit and the second drive circuit to sequentially apply a scanning voltage to the first electrode group or the second electrode group; a generation timing of an output signal from the detection pen; In a tablet device having a coordinate detection circuit for detecting coordinates on a panel indicated by the tip of the detection pen from the scanning timing of the first electrode group or the second electrode group, an output signal from the detection pen is referred to as a first slice level. Binarizing means for binarizing at a slice level different from the second slice level higher than the first slice level, and for sending the binarized signal binarized at the first slice level to the coordinate detection circuit; The binarizing means monitors a binarized signal binarized at the second slice level by the binarizing means. If the level of the binarized signal exceeds a threshold, the binarized signal is closest to the point in time at which the threshold is exceeded. A tablet device provided with erroneous detection determination means for determining the coordinates on the panel detected by the coordinate detection circuit at the time of the detection as erroneous detection coordinates.