KR100272514B1 - Ips mode lcd apparatus equipped with position detection function - Google Patents

Abstract

PURPOSE: An in-plane switching mode liquid crystal display is to prevent an aperture rate from being reduced and an image quality from being deteriorated due to static electricity. CONSTITUTION: The liquid crystal display comprises an upper glass substrate(31), a lower glass substrate(33), and a liquid crystal sealed between the upper and lower glass substrates. A black matrix layer(35) is formed on the upper glass substrate and is applied with a position signal. A color filter layer(37) is formed between the black matrix layers. An overcoat layer939) is formed on the entire surface of the color filter layer. A data line(11) is formed on the lower glass substrate opposed to the black matrix layer, and an opposed electrode(17) is formed on one side of the data line. A pixel electrode(15) is formed on the other side of the data line. The black matrix layer includes a driving signal applying unit(43) for applying a driving AC signal to the black matrix layer, and a ground signal applying line(45).

Description

IPS mode liquid crystal display with position detection

The present invention relates to a liquid crystal display device, and more particularly, to an IPS mode liquid crystal display device having a position detection function suitable for simultaneously performing electrostatic shielding and position detection in the IPS mode.

Generally, a liquid crystal display cell is basically made of two glass substrates containing liquid crystals inside, and is divided into TN and STN according to the display mode.

Although TN and STN have many variables for the material, driving, electrode pattern, and display size of liquid crystal in the process of the liquid crystal display device, many of the assembling process steps are required to perfect the process processor of the LCD. Done.

In general, there are two types of TN-mode LCDs, a reflective type and a transmission type, depending on the display mode.

In active matrix LCDs, transmission types are commonly used for color displays.

In transmission mode, the display is activated by a fluorescent lamp attached to the back of the panel.

The panel consists of two plates, the bottom plate and the top plate. The lower plate is arranged with the TFT array and the upper plate is arranged with the black matrix layer and the color filter layer.

The lower plate and the upper plate are designed so that the TFT and the color filter layer face each other.

The liquid crystal is injected between the two plates and filled in a small gap of several micrometers with maximum uniformity.

Twisted Nematic liquid crystals are generally used and therefore require a polarizing film on the outer surface of each substrate.

The pixels are formed on the lower substrate and arranged in the form of X-Y metrics.

Each pixel has an amorphous silicon TFT that acts like an analog switch to control the charge accumulated in the liquid crystal capacitor.

The capacitance is formed between the pixel electrode on the lower substrate and the common electrode on the upper electrode.

The color filter layer on the upper substrate is composed of three colors R, G, and B.

An electrode line is formed on the TFT substrate and controls the TFT operation at each pixel. Each unit pixel circuit is formed at the intersection of bus lines.

Here all bus lines are connected to the drive ICs around the screen.

TFT-LCDs can be thought of as analog memory devices and one pixel is formed at the intersection of the gate and data bus lines.

Each pixel includes a TFT and a pixel load capacitor and includes a liquid crystal capacitance formed between the common electrode on the upper plate and the pixel electrode on the lower plate.

Hereinafter, a conventional IPS mode liquid crystal display device will be described with reference to the accompanying drawings.

1A to 1B are plan views of a conventional IPS mode liquid crystal display (LCD).

As illustrated in FIG. 1A, a data line 11 formed in one direction, a gate line 13 formed in a direction crossing the data line, and a pixel defined by the gate line 13 and the data line 11 are illustrated. At the intersection of the pixel electrode 15 formed at the periphery of the region, the counter electrode Vcom 17 formed in a T shape across the pixel electrode 15, and the gate line 13 and the data line 11. It consists of the TFT 19 arrange | positioned.

FIG. 1B is similar to FIG. 1A and differs only in the arrangement of the counter electrode 17 and the pixel electrode 15.

The LCD of the IPS mode, unlike the LCD of the conventional TN mode, displays an image by controlling the amount of transmission by controlling the liquid crystal molecules by a transverse electric field formed between the pixel electrode and the counter electrode.

In the LCD of the TN mode, ITO (Vcom) existing on the upper plate is formed on the lower plate, that is, the substrate such as the pixel electrode.

2A to 2B are cross-sectional views briefly illustrating a bottom glass in which the pixel electrode and the counter electrode shown in FIG. 1 are formed together.

FIG. 2A corresponds to FIG. 1A and FIG. 2B corresponds to FIG. 1A.

As shown in Figs. 2A to 2B, reference numeral 11 is applied to a data line, reference numeral 15 is a pixel electrode, reference numeral 17 is a counter electrode, and reference numeral 21 is applied between the pixel electrode and the counter electrode. Is a signal electric field, and reference numeral 23 denotes a noise electric field.

Here, Cp denotes the capacitance between the pixel electrode 15 and the counter electrode 17.

3 is a cross-sectional view of an IPS mode liquid crystal display device according to the prior art.

As shown in FIG. 3, the upper plate glass 31 and the lower plate glass 33 are largely formed, and the black matrix layer 35 formed on the upper plate glass 31 with a predetermined interval therebetween, and the black matrix layer 35. And a color filter layer 37 formed therebetween and an overcoat layer 39 formed on the entire surface including the color filter layer 37. The lower plate glass 33 has a data line facing the black matrix layer 35. 11, a counter electrode 17 formed on one side of the data line 11, and a pixel electrode 15 formed on the other side of the data line 15.

The liquid crystal LC is encapsulated on the upper glass 31 and the lower glass 33, and an ITO layer 41 is formed on the rear surface of the upper glass 31 to block static electricity applied from the outside. .

That is, when contacted with an externally charged object, the upper glass 31 is also charged and the charged upper glass 31 directly affects the arrangement of liquid crystal molecules.

The influence of the charged top glass 31 as described above is a factor that reduces the image quality of the light transmission amount is not controlled by the data voltage.

Therefore, in order to prevent a decrease in image quality due to static electricity, an ITO layer 41, which is a transparent conductor, is formed on the rear surface of the upper glass 31 to prevent static electricity from being applied from the outside.

However, the liquid crystal display of the conventional IPS mode as described above has the following problems.

Although the ITO layer is transparent, the process is complicated because it reduces the transmittance of back-light light and adds the process of forming the ITO layer on the back surface of the top glass.

In particular, in the IPS mode, since both the pixel electrode and the counter electrode are formed on the bottom glass, the aperture ratio is very low.

Such a decrease in the aperture ratio causes an increase in the driving voltage, leading to an increase in power consumption.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and prevents a decrease in aperture ratio (or transmittance) and at the same time prevents a decrease in image quality due to static electricity and detects a position such as a separate digitizer or tablet. An object of the present invention is to provide an IPS mode liquid crystal display device having a position detection function that does not require an element.

1A to 1B are plan views of a conventional IPS mode liquid crystal display (LCD).

2A through 2B are cross-sectional views illustrating a capacitor coupling phenomenon according to the bottom glass of FIG. 1.

3 is a cross-sectional view of an IPS mode liquid crystal display device according to the prior art.

4 is a cross-sectional view of a liquid crystal display device in IPS mode having a position detection function according to a first embodiment of the present invention.

5 is a plan view of an IPS mode liquid crystal display device having a position detection function according to a first embodiment of the present invention.

6 is an equivalent circuit diagram showing in more detail the black matrix layer of the present invention.

7 is a cross-sectional view of an IPS mode liquid crystal display device having a position detection function according to a second embodiment of the present invention.

8 is a plan view of a position detection device for explaining the structure of the ITO layer according to the second embodiment of the present invention;

Explanation of symbols for main parts of the drawings

11: data line 13: gate line

15 pixel electrode 17 counter electrode

31: upper glass 33: lower glass

35: black matrix layer 35a: black matrix pattern

37: color filter layer 39: overcoat layer

41: ITO layer 43a, 43b, 43c, 43d: drive signal applying unit

45: ground signal applying line 51,53: X-axis, Y-axis grid

55: equipotential holding resistance 57: equipotential compensation resistance

60: active area

The IPS mode liquid crystal display device having a position detection function according to the present invention for achieving the above object is formed on the first substrate and the first substrate and used as a position detection element in the liquid crystal display device of the IPS mode. A black matrix layer for bypassing static electricity flowing from the outside, a second substrate, a data line formed on the second substrate so as to face the black matrix layer, and pixel electrodes and opposite electrodes formed on both sides of the data line, respectively And a liquid crystal encapsulated between the first substrate and the second substrate.

Hereinafter, an IPS mode liquid crystal display having a position detecting function according to the present invention will be described with reference to the accompanying drawings.

Fig. 4 shows a first embodiment according to the liquid crystal display of the IPS mode having the position detection function of the present invention.

First, in order to block static electricity, the present invention does not separately form an ITO layer on the rear surface of the top glass, and uses the black matrix layer of the liquid crystal display as a position detection device and simultaneously bypasses static electricity applied to the outside. It is for.

As shown in FIG. 4, a liquid crystal (LC) enclosed between the upper glass 31 and the lower glass 33, and the upper glass 31 and the lower glass 33 is largely configured, and is used for position detection. The color filter layer 37 and the color filter layer 37 formed between the black matrix layer 35 formed in a matrix form on the upper plate glass 31 and the black matrix layer 35 are applied to the position signal. It consists of an overcoat layer 39 formed on the front surface.

The data line 11 formed on the lower plate 33 to face the black matrix layer 35, the counter electrode 17 formed on one side of the data line 11, and the other side of the data line. It consists of the pixel electrode 15.

In the first embodiment of the present invention, the black matrix layer 35 formed on the upper plate glass 31 is used as the position detecting element.

That is, in order to use the black matrix layer 35 as the position detecting element as shown in FIG. 4, a driving AC signal for position detection is applied from one side of the upper plate glass 31 to the black matrix layer 35. The driving signal applying unit 43 and a ground signal applying line 45 for applying a ground signal to the black matrix layer 35 on the other side of the upper glass 31 are further configured.

In this case, the driving signal applying unit 43 and the ground signal applying line 45 may change signals applied according to a signal application direction.

The IPS mode liquid crystal display device having a position detection function according to the first embodiment of the present invention will be described in detail as follows.

5 is a plan view of an IPS mode liquid crystal display device having a position detection function according to a first embodiment of the present invention.

As shown in FIG. 5, drive signal applying units 43a, 43b, 43c, 43d located near the four corners of the upper plate glass 31 to apply the position detection AC signal to the position detecting element, and in the active region. X-axis grids 51 formed in one direction at a predetermined interval from each other, Y-axis grids 53 formed in a direction crossing the X-axis grids 51, and transmitted from the driving signal applying unit 43 And the equipotential holding resistor 55 and the equipotential compensating resistors 57 for compensating for the potential to achieve the equipotential when the position detecting AC signal is applied to the X and Y axis grids 51 and 53.

Here, reference numeral "59" denotes a signal transfer resistance that transfers the drive AC signal transmitted from each driving signal applying unit 43a, 43b, 43c, 43d to the equipotential holding resistor 55, and the equipotential compensation resistor ( 57 is formed between the equipotential holding resistor 55 and the X-axis and Y-axis grids 51 and 53 so that driving AC signals transmitted from the equipotential holding resistors 55 are applied to the X- and Y-axis grids 51, respectively. Compensation for the potential to achieve the equipotential when delivered to 53).

Reference numeral 60 denotes an active area in which an image of the LCD is displayed, and equipotential compensation resistors 57 are formed in a non-active area other than the active area as shown in FIG.

Therefore, the equipotential compensation resistors 57 do not affect the size of the active region.

In addition, the X-axis grid and Y-axis grid (51, 53) is made of a black matrix layer 35, the drive signal applying unit (43a, 43b, 43c, 43d) is the upper plate glass (33) through the lower plate glass (33) And a signal is applied.

An equivalent circuit showing the black matrix layer of the present invention configured as described above in more detail is shown in FIG.

As shown in FIG. 6, it can be seen that resistors r are formed in all directions around the intersection point of the X-axis grids 51 and the Y-axis grids 53.

The operation of the IPS mode liquid crystal display device having the position detection function according to the first embodiment of the present invention configured as described above is as follows.

As shown in FIG. 5, first, the position detection AC signal is transmitted through the drive signal applying units 43a and 43c of the drive signal applying units 43a, 43b, 43c, and 43d at the four corners of the upper plate glass 31. As shown in FIG. When applied, the AC signals are transmitted to the far right through the X-axis grids 51.

In this case, as shown in FIG. 6, since resistances are formed in every grid, a potential difference exists at each point from left to right.

Similarly to the X axis, the position detection AC signal may be transferred to the Y axis grid 53 through the drive signal applying units 43a and 43b.

In this way, when a driving signal is applied to the X and Y axes, and the electronic pen is contacted at an arbitrary point, the capacitive coupling effect between the electronic pen and the black matrix layer composed of the X and Y axis grids 51 and 53 is applied. The signal is induced by the electronic pen.

Therefore, by calculating the signal induced in the electronic pen, the position can be detected at any point.

In this case, even if static electricity is applied from the outside, it may be bypassed to the outside through the black matrix layer 35 formed on the top glass 31 as shown in FIG.

That is, in order to use the black matrix layer 35 as a position detecting element, a driving signal should be applied to one side and a ground signal should be applied to the other side, so that when the static electricity flows from the outside, the black matrix layer 35 Static electricity is discharged along the path PATH of the driving signal.

7 is a view for explaining a second embodiment of the IPS mode liquid crystal display apparatus having the position detection function of the present invention.

According to a second embodiment of the present invention, an ITO layer for electrostatic shielding is formed between upper glass and lower glass.

The position detection AC signal is applied to the electrostatic shielding ITO layer, and the electrostatic shielding ITO layer is used as a position detecting element.

That is, as shown in FIG. 7, the upper glass 31 is composed of a liquid crystal LC formed between the upper glass 31 and the lower glass 33 and the upper glass 31 and the lower glass 33. ) A plurality of black matrix layers 35 formed at predetermined intervals, a color filter layer 37 formed between each of the black matrix layers 35, and an overcoat layer formed on the entire surface including the color filter layer 37. 39 and an electrostatic shielding ITO layer 41 formed on the overcoat layer 39 and to which an AC signal for position detection is applied.

In addition, the lower plate 33 has a data line 11 formed to face the black matrix layer 35, a counter electrode 17 formed at one side of the data line 11, and another side of the data line. The formed pixel electrode 15 is constituted.

According to the second embodiment of the present invention, an AC signal for position detection is applied to the ITO layer to use the ITO layer as a grid electrode for position detection.

In addition, the structure of the ITO layer is patterned as follows to minimize capacitive coupling occurring due to the structure between the black matrix layer 35 and the ITO layer 41.

8 is a plan view of a position detection apparatus for explaining the structure of the ITO layer according to the second embodiment of the present invention.

Between the black matrix patterns 35a formed in a matrix form, the first ITO layer 41a used as a grid in the X-axis direction for position detection between the adjacent black matrix patterns 35a, and a grid in the Y-axis direction. A second ITO layer 41b used in the direction intersecting the first ITO layer 41a, and a pixel patterned to be equal to the width of the first ITO layer 41a below the first ITO layer 41a. And an electrode (not shown in the figure).

Here, reference numeral 43a denotes a drive signal applying unit, and reference numeral 55 denotes an equipotential holding resistor. Reference numeral 57 denotes an equipotential compensation resistor and 59 a signal transfer resistance.

The IPS mode position detection apparatus according to the second embodiment of the present invention applies a position signal for position detection to the first and second ITO layers 41a and 41b patterned to have the same width as the pixel electrode.

That is, since a signal is not applied as in the conventional ITO layer for the common electrode, when patterning as shown in FIG. 8, it does not matter even if the resistance is high.

Since the distance between the first ITO layers 41a is formed at a predetermined distance, the capacitance formed between the adjacent ITO layers and the black matrix pattern is significantly reduced.

Of course, the 2nd ITO layer 41b is also the same as the 1st ITO layer 41a.

Thus, the capacitive coupling effect can be significantly reduced.

In addition, since the width of the pixel electrode (not shown in the drawing) is much larger than the width of the black matrix pattern, the coupling effect with the electronic pen becomes very large, and thus the size of the signal held in the electronic pen increases. / N ratio) is improved.

As described above, the IPS mode liquid crystal display device having the position detection function of the present invention has the following effects.

Firstly, the light transmittance is prevented from being reduced by the ITO layer used for the electrostatic shielding in the IPS mode liquid crystal display device. Static electricity can be prevented without forming.

Second, it is possible to detect the position using an ITO layer for electrostatic shielding without using a separate position detecting element.

Claims (15)

In the liquid crystal display of the IPS mode, A first substrate, A black matrix layer formed on the first substrate and used as a position detecting element and bypassing static electricity flowing from the outside; A second substrate, A data line formed on the second substrate so as to face the black matrix layer; A pixel electrode and an opposite electrode formed on both sides of the data line, And an liquid crystal encapsulated between the first substrate and the second substrate. The method of claim 1, And a color filter layer and an overcode layer on the black matrix layer. The method of claim 1, And a driving AC signal for position detection is applied to the black matrix layer. The method of claim 1, And a driving signal applying unit configured to apply driving signals to four corners of the first substrate, wherein the driving signal applying unit is further configured. The method of claim 4, wherein And the equipotential holding resistor and the equipotential compensating resistor are connected to the driving signal applying unit to compensate the potential difference of the driving signal. The method of claim 5, And the driving signal applying unit applies the driving signal to the black matrix layer through the equipotential sustaining resistor and the equipotential compensating resistor. The method of claim 1, The black matrix layer is an IPS mode liquid crystal display device having a position detection function, characterized in that the X-axis and Y-axis is formed in a matrix form intersecting each other. A first substrate, A black matrix layer formed in a matrix form formed on the first substrate; A color filter layer formed between the black matrix layers; An overcoat layer formed on the color filter layer; An ITO layer formed on the overcoat layer and used as a position detection element for position detection and bypassing static electricity introduced from the outside; A second substrate, A data line formed on the second substrate at a predetermined interval; A pixel electrode and an opposite electrode formed on both sides of the data line, And an liquid crystal encapsulated between the first substrate and the second substrate. The method of claim 8, And a drive AC signal for position detection is applied to the ITO layer. The method of claim 8, And the ITO layer has a matrix shape in which an X-axis and a Y-axis cross each other. The method of claim 8, And a driving signal applying unit configured to apply driving signals to four corners of the first substrate, wherein the driving signal applying unit is further configured. The method of claim 11, And the equipotential holding resistor and the equipotential compensating resistor are connected to the driving signal applying unit to compensate the potential difference of the driving signal. The method of claim 12, And the driving signal applying unit applies the driving signal to the ITO layer through the equipotential sustaining resistor and the equipotential compensating resistor. The method of claim 8, And a black matrix layer having a width smaller than that of the ITO layer on both sides of the ITO layer. The method of claim 14, The interval between the ITO layers is patterned to be wider than the interval between the black matrix layers IPS mode liquid crystal display having a position detection function