JP2863057B2 - Display integrated 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 display-integrated tablet 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.

Therefore, as a tablet that eliminates such a drawback, a display-integrated tablet device as shown in FIGS. 5 and 6 has recently been proposed. These display-integrated tablet devices also serve as display electrodes of a liquid crystal display and coordinate detection electrodes of a capacitance-type tablet device. As shown in FIG. 7, 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. 5 shows a duty type liquid crystal panel 1.
Is a display-integrated tablet device. In FIG. 5, a liquid crystal panel 1 has 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 (which are arranged orthogonally 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.

FIG. 6 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.

The source electrode of the TFT 25 is connected to a source bus line electrode S, while the gate electrode is connected to a gate bus line electrode G. The pixel electrode 24 is connected to the drain electrode.

The above-mentioned duty type liquid crystal panel 1
And the display-integrated tablet device having the active matrix type liquid crystal panel 21 operate as follows. That is, in 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 (gate drive circuit 22) and the segment drive circuit 3 (source drive circuit 23). You. Then, a drive pulse of a common electrode drive signal (gate bus line electrode drive signal) is applied to the common electrode Y (gate bus line electrode G) by the common drive circuit 2 (gate drive circuit 22). On the other hand, the segment drive circuit 3 (source drive circuit 23)
As a result, a drive pulse of a segment electrode drive signal (source bus line electrode drive circuit) is applied to the segment electrode X (source bus line electrode S). Thus, an image is displayed by operating in the same manner as a normal liquid crystal panel having no tablet function.

On the other hand, during the coordinate detection period, various detection control signals from the detection control circuit 6 are selected by the switching circuit 4, and the common drive circuit 2 (gate drive circuit 22) and the segment drive circuit 3 (source drive circuit 23) ). And the duty type liquid crystal panel 1
If the display-integrated type tablet device having the common electrode scan signal y ₁ ~y _n (hereinafter the common electrode Y ₁ to Y _n by the common driving circuit 2, any of the common electrode scan signal y
) Are sequentially applied as shown in FIG. On the other hand, scanning pulses of segment electrode scanning signals x _{1 to} x _n (hereinafter, an arbitrary segment electrode scanning signal is referred to as x) are sequentially applied to the segment electrodes X _{1 to} X _m by the segment driving circuit 3 in the same manner.

As shown in FIG. 7, 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.

In the case of the display-integrated tablet device having the active matrix type liquid crystal panel 21, the gate drive circuit 22 is provided similarly to the case of the display-integrated tablet device having the duty type liquid crystal panel 1. Thus, the scanning pulse of the gate bus line electrode scanning signal g is sequentially applied to the gate bus line electrode G. On the other hand, the scanning pulse of the source bus line electrode scanning signal s is sequentially applied to the source bus line electrode S by the source driving circuit 23.

Then, the detection pen 8 is connected to the liquid crystal panel 21.
And detects the voltage induced on the detection electrode of the detection pen 8 by the electrostatic coupling between the detection electrode of the detection pen 8 and the gate bus line electrode G or the source bus line electrode S. The coordinates of the tip of the detection pen 8 are obtained by the detection circuit 10 or the y-coordinate detection circuit 11.

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. 9, the tip of the detection pen 8 is covered with a tip dielectric 33 having an insulating property. This is the liquid crystal panel 1 or liquid crystal panel 2
This is to prevent the input surface of the input panel 31 that protects the input panel 1 from being scratched by the detection electrode 32 to be scratched. Further, this is to prevent the internal circuit from being damaged when the detection electrode 32 comes into contact with a voltage application unit of an external electronic device, clothing, or the like. In FIG. 9, the liquid crystal panels 1, 2
Although the input panel 31 is provided on the input surface 1, a thin film may be directly adhered to the surfaces of the liquid crystal panels 1 and 21. Alternatively, the liquid crystal panels 1 and 21 may be used as they are as input surfaces.

[0014]

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. 5) of the common electrode Y causes the upper electrode (FIG. 5).
In the case of (1), since the lower electrode is scanned by the common electrode Y), a small gap (about 3
0 μm), and the induced voltage when scanning the lower electrode is a few mV, which is particularly weak.

In the case of a display-integrated tablet device having an active matrix type liquid crystal panel 21 shown in FIG. 6, a source bus line electrode S and a gate bus line electrode G for driving the TFT 25 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 detected during the coordinate detection period. The induced voltage is very weak. Therefore, it is very susceptible to external noise. There are various sources of noise, but a particular problem is that the detection pen 8 slides on the input panel 31 of the liquid crystal panel 1 or the liquid crystal panel 21 to write characters or figures at high speed. This is noise caused by frictional charging between the tip dielectric 33 covering the tip of the pen 8 and the input panel 31. The triboelectric charge is gradually attenuated by the leakage current of the tip dielectric 33 of the detection pen 8 and the input panel 31.

However, when writing is continuously performed by the detection pen 8, the voltage generated by the frictional charging exceeds the attenuation and the frictional charging voltage increases, and eventually exceeds the limit value (discharge starting voltage). Discharge occurs instantaneously between the input panel 31 and the tip dielectric 33.

The details will be described below. FIG. 10 shows that the tip dielectric 33 in FIG. 9 is made of polycarbonate,
The input panel 31 is made of acrylic, and the triboelectric charge generated when the detection pen 8 slides continuously (drawing input) on the surface of the input panel 31 is schematically shown. A positive charge is charged on the surface of the input panel 31, and a negative charge is charged on the friction surface of the tip dielectric 33. In this case, the input panel 31
On the side, friction by the detection pen 8 is less likely to be concentrated on the same point over a wide range. Therefore, the input panel 31
The charge density on the surface is low and causes little problem.

On the other hand, on the tip dielectric 33 side of the detection pen 8, the portion that rubs against the surface of the input panel 31 is always the same. Therefore, the tip dielectric 33
The frictional surface has a large charged charge density, which is a major problem for electrostatic induction type tablets. At this time, the voltage Vp of the frictional surface of the tip dielectric 33 due to frictional charging is determined by the amount of charged charge and the capacitance between the detection electrode 32 (and the ground).

FIG. 11 (a) shows that when the tip of the detection pen 8 is continuously slid on the input panel 31, the charging voltage Vp of the tip dielectric 33 increases due to frictional charging (in this example, negative voltage). Voltage). The increasing voltage Vp eventually reaches a limit value (discharge start voltage) “Vd” volts, and at the time of “↓” mark, a part of the input panel 31 is discharged to “0”.
It drops instantly to near the bolt.

Then, an impulse-like induced voltage as shown in FIG. 11B is induced in the detection electrode 32 by the discharge. This induced voltage is a voltage obtained by differentiating the charging voltage Vp. Here, the limit value Vd is usually 3
Since the discharge is completed in a very short time at a high voltage exceeding 00 volts, the differential value “d (Vd) / dt” of the charging voltage Vp at the time of discharge increases, and the induced voltage induced on the detection electrode 32 becomes May reach "1" volts. still,
The rate of change of the voltage Vp before and after discharge is extremely low,
2 contribute little to the induced voltage.

The voltage waveform shown in FIG. 1A is obtained by sequentially applying a common electrode scanning signal y (segment electrode scanning signal x) having a positive polarity scanning pulse as shown in FIG. 8 to a common electrode Y (segment electrode X). 5 shows a waveform of an induced voltage signal consisting only of an induced voltage (hereinafter, referred to as a normal detection signal) induced in the detection electrode 32 when applied to the detection electrode 32. Also, FIG.
This is a binary signal obtained by binarizing the induced voltage of (a) with a slice voltage “e ₁ ” by a comparator (not shown). This 2
Based on the generation timing of the pulse based on the normal detection signal in the digitized signal, as described above, y
The coordinates (x coordinates) can be detected.

However, when an impulse-like induced voltage (hereinafter, referred to as an erroneous detection signal) as shown in FIG. 1C (FIG. 11B) is induced in the detection electrode 32 by the above-described discharge. Is calculated by the comparator at the slice voltage “e ₁ ”.
When converted to a value, a pulse based on an erroneous detection signal is generated in addition to a pulse based on the normal detection signal as shown in FIG. Therefore, if the x-coordinate detection circuit 10 or the y-coordinate detection circuit 11 obtains a coordinate value in accordance with the pulse based on the erroneous detection signal, an erroneous tip coordinate of the detection pen 8 is detected.

Normally, an electronic device placed around an information device incorporating a display-integrated tablet device as shown in FIG. 5 or 6 emits periodic noise. Therefore, it is easy to deal with external noise. However, the impulse-like noise due to frictional charging as described above is generated at all irregularities, so that it is very difficult to deal with it.

Here, the polarity of the triboelectric charging will be briefly described. When two different types of dielectrics rub against each other, the surface of one dielectric is positively charged and the surface of the other dielectric is negatively charged. In this case, each charge polarity is determined by a combination of substances. Table 1 shows a part of the polarity series of triboelectric charging when different substances rub against each other. In Table 1, the substances listed in the upper row are more positively charged, and the substances listed in the lower row are more negatively charged.

[Table 1] According to Table 1, for example, when acrylic and polycarbonate are rubbed, the surface of the acrylic is positively charged and the surface of the polycarbonate is negatively charged.

Accordingly, an object of the present invention is to provide a display-integrated tablet device capable of stably and accurately detecting the tip coordinates of a detection pen even if noise due to frictional charging of the detection pen is detected during the coordinate detection period. Is to do.

[0029]

According to a first aspect of the present invention, a first electrode group arranged in one direction and a second electrode group arranged in another direction different from the one direction are provided. A display panel having: a detection pen having a detection electrode at its tip electrostatically coupled to the first electrode group and the second electrode group of the display panel; a first drive circuit for driving the first electrode group; A second drive circuit for driving the second electrode group; a display control circuit for controlling the first drive circuit and the second drive circuit during a display period to display an image on the display panel; A detection control circuit for controlling a first drive circuit and the second drive circuit to separately apply a scan voltage to the first electrode group and the second electrode group to sequentially scan each electrode group;
A display integrated type having a coordinate detection circuit for detecting coordinates on a display panel pointed 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 detection pen is covered with a tip member made of a dielectric material to protect the input surface of the detection electrode and the display panel, and the coordinate detection circuit outputs an output from the detection pen. The coordinate is detected by using only one polarity with respect to the reference voltage of the signal, and the combination of the material of the tip member of the detection pen and the material of the input surface of the display panel is determined by the detection pen. And the polarity of the triboelectric charge at the tip member of the above becomes the same one polarity as the polarity of the output signal used by the coordinate detection circuit. It is characterized in that.

According to a second invention, in the display-integrated tablet device according to the first invention, the first drive circuit and the second drive circuit are connected to the first electrode group or the second electrode group during the coordinate detection period. Are sequentially applied to each of the electrode groups, such that a scanning voltage having a polarity with respect to a reference voltage that is the same as the polarity of the triboelectric charging at the tip member of the detection pen is applied.

[0031]

In the first aspect of the present invention, during 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 separately applied to the first electrode group and the second electrode group of the display panel. Is applied to scan the electrode group. 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 coordinate detection circuit detects the coordinates on the display panel indicated by the tip of the detection pen, using only one polarity with respect to the reference voltage among the output signals from the detection pen.

At this time, due to friction between the detection pen and the input surface of the display panel, the tip member covering the detection electrode of the detection pen has the same polarity as the polarity of the output signal used by the coordinate detection circuit. A triboelectric charge of one polarity occurs. When a discharge occurs from the tip member, an erroneous detection signal having the other polarity opposite to the one is superimposed on the output signal from the detection pen. However, since the polarity of the erroneous detection signal is opposite to the polarity of the one of the output signals used in the coordinate detection by the coordinate detection circuit, the erroneous detection signal is generated by the coordinate detection circuit. This has no adverse effect on the coordinate detection by. Thus,
Even if noise due to frictional charging is detected by the detection pen, the coordinates of the tip of the detection pen are stably detected by the coordinate detection circuit.

According to the second aspect of the invention, when the first drive circuit and the second drive circuit sequentially scan the first electrode group or the second electrode group, the polarity with respect to the reference voltage is determined by frictional charging at the tip member of the detection pen. A scanning voltage having the same one polarity as the above polarity is applied to each of the electrode groups. As a result, a normal inspection signal having the same one polarity as that of the output signal used by the coordinate detection circuit at the time of coordinate detection is induced in the detection pen due to the scanning voltage. On the other hand, the polarity of the erroneous detection signal superimposed on the output signal due to frictional charging of the tip member of the detection pen is the other polarity opposite to the one polarity.

Therefore, even if an erroneous detection signal caused by frictional charging of the tip member is superimposed on an output signal from the detection pen, the coordinate detection circuit detects the detection pen based on only the normal inspection signal caused by the scanning voltage. Are detected.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. The display-integrated tablet device in this embodiment is different from the display-integrated tablet device having the duty-type liquid crystal panel 1 shown in FIG. 5 or the display-integrated tablet device having the active matrix type liquid crystal panel 21 shown in FIG. Is the same. Therefore, in the following description of the embodiments, reference numerals in FIGS. 5, 6, and 9 are used as needed.

The tip dielectric 33 of the detection pen 8 in the display-integrated tablet device of this embodiment is formed of polycarbonate, while the input panel 31 of the liquid crystal panels 1 and 21 is formed.
Is formed of acrylic. In such a case, when the user writes on the input panel 31 with the detection pen 8, the friction surface of the tip dielectric 33 is charged as shown in FIG. 10. Then, when the discharge occurs, an erroneous detection signal in the form of a positive impulse as shown in FIG. 1C is induced on the detection electrode 32 of the detection pen 8. On the other hand, the normal detection signal resulting from the scanning pulse of the electrode scanning signal applied to the segment electrode X (source bus line electrode S) or the common electrode Y (gate bus line electrode G) has a positive polarity and a subsequent negative polarity. It has a waveform consisting of

Therefore, in this embodiment, the slice voltage of a comparator (not shown) for binarizing the induced voltage induced on the detection electrode 32 of the detection pen 8 is changed to the polarity of the impulse-like erroneous detection signal. And a negative voltage “e ₃ ” which is the opposite of the above. By doing so, only the pulse based on the normal detection signal is present in the binarized signal output from the comparator as shown in FIG. 1 (e), and the detection based on the binarized signal is performed. The coordinates of the tip of the pen 8 are normal coordinates.

Next, an embodiment which further enhances the effects of the above embodiment will be described. As described above, the input panel 31
Is formed of acrylic, and the tip dielectric 33 is formed of polycarbonate, the friction surface of the tip dielectric 33 is negatively charged by writing with the detection pen 8. Therefore,
Taking the x-coordinate detection period as an example in the display-integrated tablet device having the liquid crystal panel 1 of the duty type,
As shown in FIG. 2, the polarity of the scanning pulse of the segment electrode scanning signal x applied to the segment electrode X is made negative. As a result, a normal detection signal having a waveform having a negative polarity followed by a positive polarity as shown in FIG. Therefore, by setting the slice voltage of the comparator to a negative voltage “e ₂ ”,
A binary signal as shown in FIG. 3B can be obtained.

That is, since the polarity of the impulse-like erroneous detection signal due to frictional charging as described above is positive, the polarities of the normal detection signal and the erroneous detection signal are opposite, and the slice voltage of the comparator is normally detected. By making the polarity the same as that of the signal, the signal can be easily separated.

On the contrary, for example, the input panel 3
When 1 is formed of polycarbonate and the tip dielectric 33 is formed of nylon, the friction surface of the tip dielectric 33 is positively charged. As a result, when a discharge occurs, an impulse-like erroneous detection signal having a negative polarity is induced on the detection electrode 32 of the detection pen 8. Therefore, in that case,
8, a normal detection signal having a positive polarity can be induced in the detection electrode 33 by scanning the segment electrode X with the segment electrode scanning signal x having a positive scanning pulse, and the polarity of the normal detection signal And the polarity of the erroneous detection signal can be reversed. As a result, also in this case, the pulse based on the erroneous detection signal can be removed from the binary signal obtained by setting the slice voltage of the comparator to the same polarity as the normal detection signal, and the normal detection signal can be easily separated. .

The above explanation is based on the assumption that x in the display-integrated tablet device having the liquid crystal panel 1 of the duty type.
Although the coordinate detection period has been described, the case of the y coordinate detection period and the active matrix type liquid crystal panel 2
The same applies to the case of a display-integrated type tablet device having 1.

In the above description, the induced voltage signal as shown in FIGS. 1C and 3C induced on the detection electrode 32 of the detection pen 8 is immediately converted into the slice voltage "e ₃ " by the comparator. It is described that binarization is performed using “” and the slice voltage “e ₂ ”. However, in practice, binarization is performed after several stages of amplification.

Here, when the induced voltage signal from the detection electrode 32 is amplified and then binarized as described above, an erroneous detection signal as shown in FIG. Is differentiated into a waveform as shown in FIG. That is, some results positive false detection signals have polarity is differentiated now also have a negative polarity, the level comparator slice voltage of the negative polarity portion "e _2" in the false detection signal May exceed. Then, as shown in FIG. 3 (f), the binarized signal includes a pulse based on the erroneous detection signal in addition to a pulse based on the normal detection signal, and the normal detection signal cannot be separated as it is.

Therefore, in order to prevent such a situation, the following is performed. That is, the configuration of the amplifier circuit is configured to amplify only one polarity with respect to the reference voltage of the input signal. That is, in the case of the induced voltage signal as shown in FIG. 3C, only the negative side where only the normal detection signal exists with respect to the reference voltage is amplified. By doing so, it is possible to prevent the erroneous detection signal from being differentiated and becoming partially negative. Also, at an early stage when amplifying the induced voltage signal from the detection electrode 32, the signal on the side where the erroneous detection signal exists may be removed by a diode or the like.

As described above, the polarity of the erroneous detection signal caused by the triboelectric charge induced on the detection electrode 32 is determined by the combination of the materials of the input panel 31 and the tip dielectric 33 of the detection pen 8. Moreover, the level of the erroneous detection signal is extremely high, and reaches, for example, 40 to 100 times the level of the normal detection signal based on the scanning pulse of the segment electrode scanning signal x during the x coordinate detection period. Therefore, in another embodiment, the voltage “e ₄ ” is set so that the level of the normal detection signal cannot reach and the level of the erroneous detection signal based on frictional charging reaches. Then, the induced voltage signal from the detection electrode 32 is detected by a comparator or the like of the reference voltage “e ₄ ” to detect an erroneous detection signal based on triboelectric charging, and the coordinate value detected in the x coordinate detection period or the y coordinate detection period is calculated. By invalidating or removing the detection signal existing in the x-coordinate detection period or the y-coordinate detection period, the influence of the erroneous detection signal due to the triboelectric charging can be easily removed.

In the display-integrated tablet device using the duty type liquid crystal panel 1, it is possible to simultaneously perform image display and y-coordinate detection. In this case, as shown in FIG. 4, for example, a common electrode driving signal a to z in which a slit-shaped scanning pulse for coordinate detection is superimposed on the center of a driving pulse for image display having a positive polarity is applied to the common electrode Y. Are sequentially applied. And FIG.
An induced voltage signal from the detection electrode 32 of the detection pen 8 during a period in which the level of the selection signal is “H” as shown in FIG. The y coordinate of the tip of the detection pen 8 is detected at the location.

In this case, since the scanning pulse is formed by a slit having a negative polarity with reference to the maximum voltage value in the driving pulse of the common electrode driving signals a to z, the scanning pulse is substantially negative. The common electrode Y is scanned by the scanning pulse of (i). Therefore, in such a case, it is necessary to select the materials of the tip dielectric 33 of the detection pen 8 and the input panel 31 so that the friction surface of the tip dielectric 33 is negatively charged.

In each of the above embodiments, the segment electrode X and the common electrode Y of the duty type liquid crystal panel 1 or the active matrix type liquid crystal panel 2
A display-integrated tablet device in which one gate bus line electrode G and one source bus line electrode S are shared with electrodes of an electrostatic dielectric tablet is described. However, the present invention is not limited to this. For example, all electrodes in which an electrode covered with a dielectric is used as an electrode of a display panel and the electrode of the display panel is electrostatically coupled to a detection electrode of a detection pen. The present invention can be applied to a display integrated tablet device having an electrostatic induction tablet.

Further, the liquid crystal panel 2 in each of the above embodiments is used.
TFT as the active matrix used for 1
The description is made by taking an active matrix according to the method as an example. However, the active matrix used in the present invention is not limited to this. For example, a diode type active matrix or MIM
A (metal-insulator-metal) type active matrix or a varistor type active matrix may be used.

[0050]

As is apparent from the above description, the display-integrated tablet device of the first invention covers the detecting electrode of the detecting pen with the tip member, and changes the coordinate detecting circuit to the reference voltage of the output signal from the detecting pen. The configuration of detecting the coordinates on the display panel indicated by the tip of the detection pen using only one polarity with respect to the material of the tip member of the detection pen and the material of the input surface of the display panel. Is set so that the polarity of the triboelectric charging at the tip member of the detection pen is the same as the one polarity of the polarity of the output signal used by the coordinate detection circuit. The polarity of the erroneous detection signal superimposed on the output signal due to the triboelectric charging generated in the above can be made opposite to the one polarity of the output signal used by the coordinate detection circuit.

As a result, when the coordinates detecting circuit detects the coordinates on the display panel indicated by the tip of the detection pen based on the output signals from the detection pen, the erroneous detection signal superimposed on the output signal is detected. And the coordinates can be detected based only on the normal detection signal resulting from the scanning voltage applied to each of the electrode groups. Therefore, according to the present invention, even when noise due to frictional charging of the detection pen is detected during the coordinate detection period, the tip coordinates of the detection pen can be detected stably.

In the display-integrated tablet device according to the second aspect of the present invention, when the first drive circuit and the second drive circuit sequentially scan the first electrode group or the second electrode group during the coordinate detection period, a reference voltage is applied. Since the scanning voltage is applied to each of the electrode groups so that the polarity is the same as the one polarity of the triboelectric charging at the tip member of the detection pen, the detection electrode of the detection pen is caused by the scanning voltage. And the polarity of the erroneous detection signal induced by the triboelectric charging of the tip member can be reversed. As a result, the normal detection signal in the output signal from the detection pen can be separated from the erroneous detection signal to more reliably detect the tip coordinates of the detection pen.

[Brief description of the drawings]

FIG. 1 is a diagram showing an induced voltage signal induced on a detection pen in a display-integrated tablet device of the present invention and a binarized signal obtained by binarizing the induced voltage signal with various slice voltages.

FIG. 2 is a diagram illustrating an example of a segment electrode scanning signal having a scanning pulse of a negative polarity.

3 shows an induced voltage signal induced on a detection pen when an electrode scan is performed using the segment electrode scan signal shown in FIG. 2 and a binarized signal obtained by binarizing the induced voltage signal with various slice voltages. FIG.

FIG. 4 is a diagram showing a common electrode drive signal having a positive drive pulse in which a slit-shaped scan pulse is provided at the center.

FIG. 5 is a block diagram of a display-integrated tablet device having a duty-type liquid crystal panel.

FIG. 6 is a block diagram of a display integrated tablet device having an active matrix type liquid crystal panel.

7 is an explanatory diagram of a display period and a coordinate detection period in the display-integrated tablet device shown in FIGS. 5 and 6. FIG.

8 is a diagram showing an example of a common electrode scanning signal output from the common drive circuit in FIG.

9 is a detailed view of the tip of the detection pen in FIGS. 5 and 6. FIG.

FIG. 10 is an explanatory diagram of triboelectric charges generated in the input panel and the tip dielectric in FIG. 9;

FIG. 11 is an explanatory diagram of a change in a charging voltage on a friction surface of a tip dielectric and an induced voltage induced in a detection pen due to the charging voltage.

[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 ... input panel,
32: detection electrode; 33: tip dielectric.

Claims (2)

(57) [Claims] A display panel having a first electrode group arranged in one direction and a second electrode group arranged in another direction different from the one direction, a first electrode group and a second electrode group of the display panel.
A detection pen having at its tip a detection electrode electrostatically coupled to the electrode group; a first drive circuit for driving the first electrode group;
A second drive circuit for driving the second electrode group; a display control circuit for controlling the first drive circuit and the second drive circuit during a display period to display an image on the display panel; Controlling a first drive circuit and the second drive circuit to sequentially apply a scanning voltage to the first electrode group or the second electrode group;
Coordinates for detecting coordinates on the display panel indicated by the tip of the detection pen from the detection control circuit to be applied, and 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 display-integrated tablet device having a detection circuit, the detection pen is covered with a tip member made of a dielectric material to protect the detection electrode and an input surface of the display panel, and the coordinate detection circuit Is configured to detect the coordinates by using only one polarity with respect to the reference voltage of the output signal from the detection pen, and the material of the tip member of the detection pen and the input surface of the display panel. The polarity of the triboelectric charge at the tip of the detection pen is the same as the polarity of the output signal used by the coordinate detection circuit. One and wherein the forming a set such that the polarity display-integrated type tablet device. 2. The display-integrated tablet device according to claim 1, wherein the first drive circuit and the second drive circuit sequentially scan the first electrode group or the second electrode group during the coordinate detection period. And a scanning voltage applied to each of the electrode groups such that the polarity with respect to the reference voltage is the same as the polarity of the triboelectric charging at the tip member of the detection pen.