JPH09292598A - Liquid crystal distal device provided with input function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the obtaining of an input-output integration type display device while maintaining the same small type and thin type as that of a normal display device by making the display device have an input function. SOLUTION: In the LCD of a point sequential driving system. an X conordinate detecting period equivalent to one scanning period is added in a display period and a circuit is changed over to a DC voltage source DC by a switch SW and a DC voltage is successively impressed on drain lines DL1-DLn instead of a video signal and these are made to be an X coordinate detection signal. A Y coordinate detecting period is the same as the display period and a Y coordinate detection signal shares a scanning voltage to be impressed on gate lines GL1-GLn. An input pen PEN has an electrode at its top end and generates a position detection signal by respectively forming capacitive couplings with the drain lines DLs and gate lines GLs in the X coordinate detecting period and the Y coordinate detecting period.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input / output integrated display device which allows a pen input on a display surface by adding an input function to the display device and has the appearance of a normal display device, and more particularly, The present invention relates to a display device with an input function using a liquid crystal display device as the display device.

[0002]

2. Description of the Related Art Recently, as one of the diversification of information equipment,
There is a handwriting input method. That is, by writing characters, figures, etc. directly on the input panel using a pen,
Since it enables computer input and does not require operating equipment such as a keyboard, it can be made smaller or
Suitable for portable use such as electronic notebooks. In particular, by combining a digitizer that detects the touch coordinates of the input pen with the display panel and simultaneously displaying the pen input trajectory,
An input / output integrated display device has been developed, which is configured as if writing characters on paper. As such a display panel, a flat display panel such as EL, LED, LCD is suitable. Among them, an LCD (liquid crystal display) that uses a liquid crystal as an optical member and applies a signal voltage between opposing electrodes to modulate transmitted light is
It is a small and thin display device, and is most suitable for a configuration combined with such a digitizer.

FIG. 3 is a block diagram of an input / output display device using an LCD and a digitizer. Digitizer (1)
Is applied with a predetermined measurement voltage from the position detection control circuit (2), and the input position information written to the digitizer (1) by the input pen is the X coordinate detection controlled by the position detection control circuit (2). It is two-dimensionally taken in by the circuit (3) and the Y coordinate detection circuit (4). The coordinate information detected by these coordinate detection circuits (3, 4) is A / D converted by the processing circuit (5), arithmetically processed, and sent to the display control circuit (6). The display control circuit (6) drives the scan electrode driver (7) and the signal electrode driver (8), whereby the input locus is re-output from the LCD panel (9) and visualized.

FIG. 4 is a sectional view of an integrated structure of such a digitizer (1) and an LCD panel (9). The digitizer (1) is a pair of thin transparent substrates (11, 12).
Transparent conductive resistance film (13, 14) supported on each
Are fixed and faced with each other with a slit secured by the insulating granular spacer (15). Conductive resistance film (1
3, 14) are applied with a predetermined voltage by the position detection control circuit (2), and the position pressed by the input pen (16) and brought into contact with the coordinate detection circuit (3, 14). 4) is detected. Such a position detecting method is called a resistance film pressure sensitive method.

On the other hand, the LCD panel (9) has a liquid crystal (2
6) a pair of translucent substrates (21,
22), a gate line, which is a scanning line, and a drain line, which is a signal line, are arranged on one substrate (21) so as to intersect with each other, and a thin film transistor (TFT) that is a switching element is provided at the intersection. (25)
And a display electrode (23) for driving a liquid crystal is connected to each of the TFTs (25) and the other substrate (2
A common electrode (24) is formed on one surface of the above (2), and a liquid crystal capacitor is formed at a portion facing the display electrode (23). A backlight (not shown) that is made into a surface light source is arranged behind the LCD panel (9) (downward in the figure), and a voltage corresponding to the position information detected by the digitizer (1) is applied to each liquid crystal capacitance. The LCD panel (9) which is applied and is controlled to have a transmittance distribution constituting a locus is visualized to simultaneously display the loci of input positions.

The example using the pressure-sensitive type as the digitizer (1) has been described above. In addition to this, the electrostatic induction type, that is,
With a structure in which transparent electrode lines are crossed between transparent substrates, the transparent electrode lines are sequentially scanned, and the peak voltage position of the transparent electrode group is detected by capacitive coupling with the input electronic pen to detect the pen contact position X. , A method of determining the Y coordinate, or an electromagnetic induction method, that is, a magnetic plate having X and Y directions,
The peak position of the induced voltage generated in the detection line group by sandwiching it with the detection line groups in the X and Y directions and specifying the position with an input pen composed of a bar magnet etc., causing electromagnetic induction in the Y and X directions. There is a method of determining the input coordinates by detecting.

[0007]

The conventional input / output integrated display device as mentioned above is constituted by a combination of a digitizer for detecting an input position and a display device for simultaneously displaying the input position. . In addition to the superposing method in which the digitizer and the display are simply overlapped with each other, there is a hybrid method in which the constituent elements of the digitizer and the display are partially common. In the superposition method, there are problems that the device itself becomes large due to the thickness of the digitizer and the display, or the screen becomes dark due to a decrease in transmittance during display. In addition, the hybrid system requires integration at the manufacturing stage, which raises a problem that the manufacturing cost increases.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and detects an input position on a display surface by an input device having a position detection electrode incorporated therein, and the input position or / and the input. In a liquid crystal display device with an input function for simultaneously displaying a position locus, a plurality of gate lines and drain lines are arranged on opposite surfaces so as to intersect each other, and a thin film transistor and a liquid crystal driving display electrode connected to the thin film transistor at each intersection. And a second electrode substrate having a common electrode formed on one surface on the opposite surface are bonded together with a slit, and liquid crystal is sealed in the slit. Capacitive coupling between the position detecting electrode and the gate line and drain line at the input position indicated by the input device on the surface opposite to the facing surface of the first electrode substrate. The ordinate of the input position is determined from the timing of the change in the signal voltage received by the detection electrode in the capacitive coupling portion by the scanning voltage that is formed and sequentially selected by applying the gate lines during the display period. At the same time, the abscissa of the input position is determined from the timing of the change in the signal voltage received by the position detection electrode in the capacitive coupling section by the DC voltage sequentially applied to the drain line during the non-display period. Is.

As a result, it is possible to avoid an increase in the size of the device itself or an increase in the number of steps due to the combination with the input device, and to obtain a small-sized and low-cost input / output device. As a result, the liquid crystal display device can also be used as an input device, and the increase in size of the device itself and the increase in manufacturing cost can be prevented. As a result, the detection signal of the Y coordinate is also used as the scanning voltage of the gate line, the detection period of the Y coordinate is overlapped with the display period of the display device, the Y coordinate detection period is separately provided, and the display period is shortened. There is no such thing.

Particularly, during the display period, the display is performed by sequentially applying the pixel signal voltage to the drain line during each scanning period in which the gate lines are sequentially selected, and during the non-display period. One additional scanning period having the same length as the scanning period in the display period is added, and by applying the DC voltage to the drain line in order during the added scanning period, the horizontal position of the input position can be obtained. This is a configuration for determining coordinates.

As a result, the ordinate can be detected by utilizing the so-called dot-sequential driving method in which the pixel signal voltage is sequentially applied to the drain line during one scanning period, and the normal liquid crystal display device can be detected. It is possible to add input function without significant changes from. In particular, the voltage applied to the common electrode is constant. As a result, the detection signal induced by forming capacitive coupling with the gate line and the drain line does not fluctuate under the influence of the common electrode voltage and is always kept in a constant waveform.

[0012]

1 is a block diagram showing the configuration of an LCD with an input function showing an embodiment of the present invention. The matrix circuit section on the left side of the figure is a display section that also serves as an input surface. Gate lines that are scanning lines (GL1, G
L2, ... GLm) and a drain line (D) which is a signal line
L1, DL2, ... DLn) are arranged so as to intersect with each other, and at each intersection, a switching element T
An FT (SE) and a display electrode (PX) connected to this are formed. These are formed on one substrate. In addition, a common electrode (CM) is formed on one surface on another substrate which is opposed to each other with the liquid crystal sandwiched therebetween, and a liquid crystal capacitance is formed between the common electrode (CM) and each display electrode (PX). Each gate line (GL1, GL2, ... GLm) is driven by a gate driver (GD) mainly composed of a shift register, and a constant scanning voltage is applied line-sequentially, and the same gate is applied during each scanning period. Line (GL1, GL2, ...
All the TFTs (SE) for GLm) are turned on, and during this period, the pixel signal voltage is supplied from the drain driver (DD) to each drain line (DL1, D2L, ... DLn).
Applied to each display electrode (PX) and rewritten in the next field until the O of the TFT (SE) is changed.
It is held by the FF resistance and the liquid crystal capacitance. Further, in the present embodiment, the common electrode (CM) is set to a constant level such as GND.

Further, in the present invention, the drain driver (DD) is of a dot-sequential driving system as described later in detail. That is, the drain driver (DD) is mainly composed of a shift register and an analog switch whose ON / OFF is controlled by each output of this shift register. During one scanning period, the video signal is sequentially switched by the analog switch. By sampling, the pixel signal voltage is simultaneously supplied to each drain line (DL1, D2L, ...
This is a method of sequentially supplying to DLn).

On the other hand, the right side of the figure is the controller section.
The control unit (CON) includes vertical / horizontal counters, a decoder, and the like, and controls the operation timing of the gate driver (GD) and the drain driver (DD). The video signal created by the processing unit (PRC) is supplied to the drain driver (DD) via the switch unit (SW). The processing unit (PRC) also includes a control unit (CO
N) The vertical counter is reset. Further, the controller unit is provided with a DC voltage source (DC) that generates a predetermined DC voltage, and the output of this DC voltage source (DC) is input to the switch unit (SW). The switch unit (SW) is also controlled by the control unit (CON).

The input pen (PEN) has an electrode with a high input impedance at the tip and a built-in amplifier for signal amplification. By touching the LCD, the input pen (PEN) detects a detection voltage as described in detail later. The gate lines (GL1, GL2, ... GLm) to which is applied and the drain lines (DL1, D2L, ... DLn) are capacitively coupled to generate a detection signal voltage. This detection signal is an analog signal, which is binarized by the A / D converter (AD) and supplied to the coordinate detection unit (DET). The coordinate detection unit (DET) determines the X coordinate and Y coordinate of the input position by counting a predetermined shift clock. This coordinate data is further supplied to the processing unit (PRC), where it is subjected to arithmetic processing, written in the frame memory, and further supplied as a video signal to the control unit (CON) and the switch unit (SW).

In the LCD according to the present embodiment, the input surface which also serves as the display surface has the gate lines (GL1, GL2,
... GLm) and drain lines (DL1, D2L, ...
.. DLn) is formed on the substrate side. FIG.
FIG. 6 is a timing diagram showing an operation of position detection of input coordinates and simultaneous display of input coordinates according to the embodiment of the present invention. In the present invention, the X coordinate of the input position is detected by the drain line (D
L1, D2L, ... DLn), and Y coordinate detection is performed by the gate lines (GL1, GL2, ... GLm). The Y coordinate detection is performed in parallel with the display during the display period (A), that is, during the scanning period of the gate line, and
Coordinate detection is performed during the vertical blanking period (B).

A detailed description will be given below with reference to FIGS. 1 and 2. FIG. 2A shows a vertical sync pulse (VSYN).
It is a waveform diagram of C), each field is a display period (A)
And a blanking period (B) of a fixed length. The blanking period (B) is a period during which no display operation is performed. FIG. 2B shows a Y coordinate detection signal, which also serves as a voltage applied to the gate lines (GL1, GL2, ... GLm). That is, during the display period (A), the scanning voltages sequentially applied to the gate lines (GL1, GL2, ... GLm) are the Y coordinate detection signals (Y1, Y2, ... Y).
used for m).

Further, FIG. 2C shows an X coordinate detection signal, and the X coordinate detection period corresponds to one scanning period in the blanking period (B). That is, in the vertical counter of the control unit (CON), a count that is one scan period earlier than the count start timing in a normal display is added, or a count that is one scan period later than the normal count end timing is added. Has been added.
Then, switch control is performed by the output pulse from the decoder corresponding to this, and the supply of the video signal sent from the processing unit (PRC) to the drain driver (DD) is supplied to the DC voltage source (DC). Switch. The signal sent from this DC voltage source (DC) is
That is, only during the X coordinate detection period, the video signal is supplied to the drain driver (DD) instead of the video signal. During this period, as in the display period (A), the drain driver (DD) performs a sampling operation in a dot-sequential system, and the DC voltage is applied to each drain line (DL1, DL2, ... DL).
n) are sequentially applied, and these become X coordinate detection signals (X1, X2, ... Xn). During the X coordinate detection period, since the gate driver (GD) does not operate, each drain line (DL1, DL2, ... DLn)
Even if the X coordinate detection signals (X1, X2, ... Xn) are applied to the pixel electrodes, the pixel information held in the display electrodes (PX) is not rewritten.

An LCD with an input function having the above structure
The operation of is as follows. First, by driving the LCD, the gate line (GL
1, GL2, ... GLm) are sequentially selected and a scanning voltage is applied to the display / Y coordinate detection period (A), and the display / Y coordinate detection period (A) is added to the beginning or end of the display / Y coordinate detection period (A). The blanking period (B) including the X coordinate detection period is alternately repeated.

In this state, the input pen (PEN) is used to draw characters, figures and the like on the LCD. As described above, the input surface (display surface) of the LCD is the gate lines (GL1, G).
L2, ... GLm) and drain lines (DL1, DL)
2, ... DLn) is formed on the substrate side,
The electrode at the tip of the input pen (PEN) forms a capacitive coupling with the gate line (GL1, GL2, ... GLm) and the drain line (DL1, DL2 ,. In the portion where the input pen (PEN) contacts, capacitive coupling is established with the gate lines (GL1, GL2, ... GLm) that are closest to each other during the display / Y coordinate detection period (A), and the Y coordinate detection signal is obtained. (Yh) (where 1≤h≤m)
In response to this, an analog detection signal having a peak at a position representing the Y coordinate position is generated. This analog detection signal is A
It is sent to the / D converter (AD) and binarized, and this detection pulse is sent to the coordinate detection unit (DET). The coordinate detection unit (DET) receives the same line clock and reset pulse as the gate driver (GD) from the control unit (CON). By counting this clock,
Create Y coordinate data. This data value is further sent to the processing unit (PRC) for calculation, and is temporarily stored in the frame memory as representing the Y coordinate.

In the display / Y-coordinate detection period (A), since the display operation is simultaneously performed, the scanning voltage which is also used as the detection signal voltage to the gate lines (GL1, GL2, ... GLm) is applied. While being applied, the pixel signal voltage is applied to each drain line (DL1, DL2, ... DLn). Therefore, during this period, input pen (PEN)
The analog detection signal sent out includes the peak induced by the pixel signal voltage in addition to the peak representing the Y coordinate position, but normally, the gate voltage also used as the Y coordinate detection signal and the X coordinate detection signal are used. Since the amplitude of a certain DC voltage is sufficiently larger than the pixel signal voltage and noise due to the pixel signal voltage is cut at the time of A / D conversion, the determination of the position coordinates is not affected.

On the other hand, in the X coordinate detection period in the blanking period (B), switching is performed based on the pulse output from the vertical decoder of the control unit (CON), and a DC voltage source (DC) is supplied from the video signal. And the DC voltage is supplied to the drain driver (DD). In the drain driver (DD), the supplied DC voltage signal is sampled and sequentially applied to the drain lines (DL1, DL2, ... DLn) as in the display period (A). The input pen (PEN) also forms a capacitive coupling with the closest drain lines (DL1, DL2, ... DLn), and this drain line (DL1, D2)
L2, ... DLn) is established, and an analog detection signal having a peak at a position representing the X coordinate position in response to the X coordinate detection signal (Xk) (where 1 ≦ k ≦ n). Occurs. This analog detection signal indicates the Y coordinate detection period (A).
Similarly to the above, it is sent to the A / D converter (AD) and binarized, and this detection pulse is sent to the coordinate detection unit (DET). In the coordinate detection unit (DET), the control unit (CO
It receives the same dot clock and reset pulse as the drain driver (DD) from N) and counts this clock to create X coordinate data. This data value is further sent to the processing unit (PRC) to be calculated and stored in the frame memory as the X coordinate.

The common electrode (CM) is, as described above,
Since the voltage is set to a constant level of 0 V, the detection voltage does not fluctuate due to the common electrode voltage, and a constant waveform is always obtained. The X-coordinate and Y-coordinate information created in this manner is used as a video signal representing an input position or / and a locus during the display period (A) during the drain driver (D).
It is sent to D) and the input position is displayed simultaneously. Then, in the display period (A), the Y coordinate of the input position is detected at the same time.

[0024]

According to the present invention, a liquid crystal display device with an input function is realized, and the external appearance is the same as a normal liquid crystal display device while maintaining a small size and a thin shape, and only by adding a drive circuit section such as a gate array. , Was able to have an input function. As a result, the input pen on the liquid crystal display device can be
By writing characters, figures, etc., it has become possible to perform predetermined input and simultaneously display them.

Since the liquid crystal display device with an input function has the same display panel portion as that of a normal liquid crystal panel, it can be manufactured by only mounting the drive circuit element having the constitution of the present invention on the liquid crystal display device. Is low. Further, even in a liquid layer display device in which a drive circuit unit is integrally formed on a substrate by using polycrystalline silicon as a thin film transistor, since it is a normal detection method using a dot-sequential drive method, a large circuit design is possible. There is no change, and it is realized at a low cost because it is realized only by adding a means for switching between display and detection, a DC voltage source for X-coordinate detection, and a design change for adding one count to the vertical counter and the vertical decoder.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a display device with an input function according to an embodiment of the present invention.

FIG. 2 is a timing chart showing the operation of the display device with an input function of the present invention.

FIG. 3 is a block diagram showing a configuration of a conventional input / output integrated display device.

FIG. 4 is a cross-sectional view of a conventional input / output integrated display device.

[Explanation of symbols]

 1 Digitizer 2 Position detection control circuit 3 X coordinate detection circuit 4 Y coordinate detection circuit 5 Processing circuit 6 Display control circuit 7 Scan electrode driver 8 Signal electrode driver 9 LCD panel 11,12 Thin translucent substrate 13,14 Conductive resistance film 15 Spacer 16 Input Pen 21,22 Translucent Substrate 23,24 Transparent Electrode 25 TFT 26 Liquid Crystal GL Gate Line DL Drain Line GD Gate Driver DD Drain Driver SE TFT PX Display Electrode CM Common Electrode PEN Input Pen CON Control Unit PRC Processing Unit AD A / D converter DET detection unit DC DC voltage source

Claims (3)

[Claims] 1. A liquid crystal display device with an input function, which detects an input position on a display surface by an input device having a position detection electrode built-in, and simultaneously displays the input position and / or the input position locus. A plurality of gate lines and drain lines are crossed to each other, and a thin film transistor is formed at each of these intersections, and a first electrode substrate having liquid crystal driving display electrodes connected thereto is formed. A second electrode substrate having a common electrode formed on the
Liquid crystal is sealed in the slit, and the position detection electrode, the gate line, and the drain line are provided at the input position indicated by the input device on the surface side of the first electrode substrate opposite to the facing surface. Capacitive coupling is formed between the input position and the input position from the timing of the change in the signal voltage received by the detection electrode in the capacitive coupling portion by the scanning voltage applied by sequentially selecting the gate lines during the display period. While determining the ordinate, by the DC voltage sequentially applied to the drain line during the non-display period,
The liquid crystal display device with an input function, wherein the abscissa of the input position is determined based on the timing of a change in a signal voltage received by the position detection electrode in the capacitive coupling section. 2. A display is performed by sequentially applying a pixel signal voltage to the drain line during each scanning period in which the gate line is sequentially selected during the display period, and during the non-display period. One additional scanning period having the same length as the scanning period in the display period is added, and by applying the DC voltage to the drain line in order during the added scanning period, the horizontal position of the input position can be obtained. The liquid crystal display device with an input function according to claim 1, wherein coordinates are determined. 3. The liquid crystal display device with an input function according to claim 1, wherein the voltage applied to the common electrode is constant.