KR20100071772A - Electrophoretic display - Google Patents

Abstract

PURPOSE: An electrophoretic display device with an integrated touch panel is provided to prevent cost rise and yield decrease when a touch panel is formed outside. CONSTITUTION: A gate line and a data line crosses on a first substrate(100) to define a unit pixel. A switching transistor is electrically connected to a gate line and a data line. A light sensor is formed on the first substrate. A color filter array(213) includes a transparent window and RGB color filters(213R,213G,213B) formed on a second substrate(200). An electrophoretic film(300) is positioned between the first substrate and the second substrate.

Description

Electrophoretic Display {Electrophoretic Display}

The present invention relates to an electrophoretic display device.

In general, the display device changes and displays data in an electrical format processed by the information processing device into an image that can be visually checked. An electrophoretic display (EPD) is one of such display devices, which is thinner and lighter than a cathode ray tube display or a liquid crystal display.

Specifically, the electrophoretic display device includes a lower substrate and an upper substrate on which electrodes are formed, and pigment particles interposed between the lower substrate and the upper substrate. The pigment particles move toward the lower substrate or the upper substrate according to the electric field formed between the lower substrate and the upper substrate. As such, the phenomenon in which charged particles move according to an electric field is called electrophoresis, and the electrophoretic display displays an image using electrophoresis. In particular, since the electrophoretic display device is a reflective display device that displays an image using external light, there is no need to provide a separate light source, and the pigment particles are formed in a very thin layer, which is advantageous in weight reduction and thinning.

A display device such as an electrophoretic display device may further include a touch panel for a user to operate the information processing device. When the touch panel touches a hand or an object of a specific part, the touch panel detects the touched position and outputs position information corresponding to the touched position. The information processing apparatus processes the data according to the contents indicated at the contacted position by using the position information.

As such, the touch panel is easier to operate than a keyboard or a mouse, and its use is increasing.

However, since the touch panel is provided above the display panel on which an image is displayed, the overall thickness of the display device is increased and display quality is reduced.

An object of the present invention to provide an electrophoretic display device having an integrated touch panel.

In accordance with another aspect of the present invention, an electrophoretic display device includes: a first substrate and a second substrate facing the first substrate; and gate lines and data defining unit pixels crossing each other on the first substrate. A switching transistor electrically connected to a line, the gate line and the data line, an optical sensing unit formed on the first substrate, and a red, green, blue color filter and transparent layer formed on the second substrate. A color filter array having a window, and an electrophoretic film including charged particles positioned between the first substrate and the second substrate and driven by electrophoresis, wherein the transparent window of the second substrate is provided with the first window. It is disposed so as to correspond to the photosensitive portion of the substrate.

The unit pixel may be a red unit pixel in which the red color filter is formed in a central region, a blue unit pixel in which the blue color filter is formed in a central region, a green unit pixel in which the green color filter is formed in a central region, and a white unit pixel in which a transparent window is formed. Is defined.

White regions of the transparent window are formed at edges of each of the red, green, and blue unit pixels.

The first substrate and the second substrate are formed on a plate having flexibility.

The pixel electrode may further include a pixel electrode electrically connected to the switching transistor, and a common electrode formed on the second substrate.

An off voltage line and an output scan line parallel to the gate line and insulated from the data line, and a power line and a signal output line parallel to the data line and insulated from the gate line, off voltage line and output scan line, The light sensing unit is turned on by irradiating light to a channel unit, an input terminal and a control terminal are respectively connected to the photosensitive transistor connected to the power supply line and the off voltage line, and one end thereof is connected to an output terminal of the photosensitive transistor. One end is connected to a signal capacitor connected to the off voltage line, an output terminal of the photosensitive transistor and one end and an input terminal of the signal capacitor, and an output terminal and a control terminal are respectively connected to the signal output line and the output scan line. And an output transistor.

As described above, the electrophoretic display device according to the present invention forms an optical sensing unit inside the electrophoretic display device so as to have an integrated touch panel, thereby increasing the price, yield reduction, Problems such as a decrease in reflectance and a decrease in whiteness due to the touch panel can be solved, and a thinner and cheaper display device can be realized than in the related art.

In addition, the electrophoretic display device according to the present invention as described above, by arranging the light sensing portion of the lower substrate to correspond to the white unit pixel and the white region of the upper substrate, the white region and the white region of the transparent window on which the color filter is not formed Since the light incident through the unit pixel is transferred to the light sensing unit as it is, the amount of light incident on the light sensing unit is increased, thereby making it easy to touch without deterioration of color characteristics.

Hereinafter, an electrophoretic display device having an integrated touch panel will be described with reference to the accompanying drawings.

1 is an equivalent circuit diagram of a unit pixel of an electrophoretic display device having an integrated touch panel according to the present invention.

As shown in FIG. 1, the unit pixel includes a switching transistor T1 connected to the display signal lines 121 and 171, an electrophoretic capacitor Cep, and a storage capacitor Cst connected thereto. Include.

The switching transistor T1 is a three-terminal element whose control terminal G and input terminal S are connected to the gate line 121 and the data line 171, respectively, and the output terminal D is an electrophoretic capacitor ( Cep) and sustain capacitor Cst.

The unit pixel further includes a light sensing unit including a light sensing transistor T2, an output transistor T3, and a sensing signal capacitor C.

The photo-sensing transistor T2 is a three-terminal element whose control terminal G and input terminal S are connected to the off voltage line 122 and the power supply line 174, respectively, and the output terminal D is a sensing signal capacitor. It is connected to one end of (C) and the input terminal S of the output transistor T3.

When light is irradiated to the channel semiconductor, the photonic transistor T2 forms a photocurrent formed by an amorphous silicon layer, and the photocurrent is directed toward the sensing signal capacitor and the output transistor by the voltage applied to the power supply line 174. And the sensing signal capacitor C stores it as a signal voltage. Here, the other end of the sensing signal capacitor C is connected to the off voltage line 122, and the off voltage line 122 allows the photosensitive transistor T2 to be operated only by light without being affected by the surrounding voltage. Maintain the off voltage.

The output transistor T3 is also a three-terminal element whose control terminal G and output terminal D are connected to the output scan line 123 and the signal output line 172, respectively. The output transistor T3 operates when an on voltage is applied to the output scan line 123 to output the sense signal voltage stored in the sense signal capacitor C to the signal output line 172.

The unit pixel as described above will be described in more detail.

FIG. 2A illustrates an arrangement of unit pixels formed in an electrophoretic display device having an integrated touch panel, and FIG. 2B illustrates a cross-sectional view taken along the line II ′ of FIG. 2A.

First, as illustrated in FIG. 2A, the unit pixels formed in the electrophoretic display device having the integrated touch panel are quad type (quad type) and include a red unit pixel (R) having a red color filter and a green color filter. The green unit pixels G, the blue unit pixels B provided with the blue color filter, and the white unit pixels W having the transparent window are disposed.

In this case, the red color filter 213R is disposed in the center region of the red unit pixel R, and the red color filter 213R is not formed at the edge of the center region of the red unit pixel R, so that the white region of the transparent window ( 214W) is formed.

Similarly, the white region 214W of the transparent window is formed at each of the edges of the green unit pixels and the edges of the blue unit pixels.

FIG. 2B is a cross-sectional view taken along the line II ′ of FIG. 2A, and more specifically illustrates each unit pixel.

The electrophoretic display device according to the present invention is divided into an upper substrate 200 and a lower substrate 100 and an electrophoretic film 300 positioned between them.

First, the upper substrate 200 includes a color filter array 213 in which red, green, and blue color filters 213R, 213G, and 213B and a transparent window 213W formed on the upper plate 211 are arranged. The passivation layer 215 and the common electrode 217 sequentially formed thereon are provided.

The white region 214W of the transparent window in which the color filter is not formed is formed between adjacent color filters.

The upper plate 211 may be a flexible plastic, an easily bent base film, or a flexible metal.

In addition, the electrophoretic film 300 is composed of a capsule 301 containing charged pigment particles.

The capsule 301 includes black dye particles 301a in response to the positive voltage, white dye particles 301b in response to the negative voltage, and a solvent 301c.

In addition, the lower substrate 100 may include a gate line (121 of FIG. 1), a gate electrode 124 of the switching transistor T1 protruding from the gate line, and an off voltage line (122 of FIG. 1) on the lower plate 110. ), A gate electrode 126 and an output scan line 123 of the photosensitive transistor T2 connected thereto, and a gate electrode 128 of the output transistor T3 connected thereto are formed.

The lower plate 110 may be made of a flexible plastic, an easily bent base film, or a flexible metal.

A gate insulating layer 140 is formed on the gate line 121, the off voltage line 122, the output scan line 123, and the gate electrodes 124, 126, and 128.

The semiconductor layers 154, 156, and 158 forming the channel portions of the three transistors T1, T2, and T3 are formed on the gate insulating layer 140. The semiconductors 154, 156, and 158 are made of an amorphous silicon layer.

On each of the semiconductor layers 154, 156, and 158, ohmic contact layers 163/165, 162/164, and 166/168 formed of an n + amorphous silicon film doped with high concentration of n-type impurities separated in both sides are formed.

On the ohmic contact layers 163/165, 162/164, and 166/168, the source electrodes 173, 172, and 176 and the drain electrodes 175, 174, and 178 of the three transistors T1, T2, and T3 are provided. A line (171 in FIG. 1), a signal output line (172 in FIG. 1) and a power supply line (174 in FIG. 1) are formed.

Here, the source electrode 173 of the switching transistor T1 is connected to the data line 171, the source electrode 172 of the photosensitive transistor T2 is connected to the power line 174, and the output transistor ( The drain electrode 178 of T3 is connected to the signal output line 172. The drain electrode 174 of the photosensitive transistor T2 is connected to the source electrode 176 of the output transistor T3, and the drain electrode 175 of the switching transistor T1 is the pixel electrode 190 described later. ) The data line 171 mainly extends in the vertical direction to intersect the gate line 121 and forms a source electrode 173 having a plurality of branches extending from each data line 171. The pair of source and drain electrodes 173 and 175 are at least partially positioned on the upper portions of the ohmic contacts 163 and 165, respectively, and are separated from each other and disposed opposite to the gate electrode 123.

The data lines 171, the signal output lines 172, the power lines 174, and the source electrodes 173, 172, and 174 and the drain electrodes 175, 174, and 178 of the transistors T1, T2, and T3 are disposed on the data lines 171, the signal lines, and the drain electrodes 175, 174, and 178. The passivation layer 180 is formed. In this case, a contact hole 181 exposing the drain electrode 175 of the switching transistor T1 is formed in the passivation layer 180.

On the other hand, one switching transistor T1 is disposed in each unit pixel, and an optical sensing unit including the photosensitive transistor T2, the output transistor T3, and the sensing signal capacitor C is formed for each unit pixel. Alternatively, one unit may be arranged for every five unit pixels.

In this case, the light sensing unit senses the amount of incident external light and outputs a detection signal, and is disposed to correspond to the white unit pixel 213W and the white area 214W of the upper substrate 200 to increase the amount of incident light. do.

As such, by arranging the light sensing transistor T2 of the lower substrate so as to correspond to the white unit pixel 213W and the white region 214W of the upper substrate, the white region 214W of the transparent window on which the color filter is not formed and Since the light incident through the white unit pixel 213W is transmitted to the photosensitive transistor T2 as it is, the photosensitive transistor of the photosensitive unit is lighter than the electrophoretic display device in which the white region 214W and the white unit pixel 213W are not formed. The amount of light incident to the is increased.

The electrophoretic display device as described above is a reflection type and uses external light without using a backlight. As shown in FIGS. 3A and 3B, when an object 80 such as a finger is placed on the upper substrate, external light that is incident is blocked by the object, and the photosensitive transistor T2 disposed at the corresponding position is turned off. The signal voltage of the sense signal capacitor C is not stored. On the other hand, the photosensitive transistor T2 disposed in another portion remains on and stores a constant signal voltage in the sensing signal capacitor C. FIG. At this time, in order for the other portion of the photosensitive transistor T2 to remain in the on state, a sufficient amount of light must be incident to the photosensitive transistor T2. In this state, the scan signal is sequentially applied to the output scan line 123 to scan and receive a sense signal stored in the sense signal capacitor C to determine a position where the signal is not output as the touched position.

When the white region 214W and the white unit pixel 213W are not formed and only the red, blue, and green color filters are disposed adjacent to each other, the color filter array is disposed on the electrophoretic film and the lower substrate. Since the external light is absorbed by the red, blue, and green color filters themselves, the amount of light flowing into the light sensing unit is insufficient, resulting in the limitation of sensing.

Accordingly, by arranging the light sensing unit of the lower substrate so as to correspond to the white unit pixels 213W and the white region 214W of the upper substrate as described above, the white region 214W and the white of the transparent window where the color filter is not formed. Since the light incident through the unit pixel 213W is transmitted to the photosensitive unit as it is, the amount of light incident to the photosensitive unit is increased than that of the electrophoretic display device in which the white region 214W and the white unit pixel 213W are not formed.

As described above, when the touch panel is formed outside the electrophoretic display device, there are problems such as a price increase, a yield decrease, a decrease in reflectance and a decrease in whiteness caused by the touch panel. The above problem can be solved by forming the inside of the display panel, and a thinner and cheaper display device can be realized.

In addition, the light sensing unit of the lower substrate corresponds to the white unit pixel 213W and the white region 214W of the upper substrate, whereby the white region 214W and the white unit pixel 213W of the transparent window on which the color filter is not formed. Since the incident light is transmitted to the light sensing unit as it is, the amount of light incident on the light sensing unit is increased to facilitate the touch without deterioration of color characteristics.

1 is an equivalent circuit diagram of a unit pixel of an electrophoretic display device having an integrated touch panel according to the present invention.

2A is a diagram illustrating an arrangement of unit pixels formed in an electrophoretic display device having an integrated touch panel according to the present invention.

FIG. 2B is a cross-sectional view taken along the line II ′ of FIG. 2A.

3A and 3B are cross-sectional views of an electrophoretic display device according to an embodiment of the present invention.

Claims (6)

A first substrate and a second substrate facing the first substrate, A gate line and a data line crossing each other on the first substrate to define unit pixels; A switching transistor electrically connected to the gate line and the data line; An optical sensing unit formed on the first substrate; A color filter array having red, green, and blue color filters and a transparent window formed on the second substrate; An electrophoretic film is disposed between the first substrate and the second substrate and includes charged particles driven by an electrophoresis method. And the transparent window of the second substrate is disposed to correspond to the light sensing unit of the first substrate. The method of claim 1, wherein the unit pixel And a red unit pixel in which the red color filter is formed in the center area, a blue unit pixel in which the blue color filter is formed in the center area, a green unit pixel in which the green color filter is formed in the center area, and a white unit pixel in which a transparent window is formed. Electrophoretic display device. The electrophoretic display device according to claim 2, wherein a white area of the transparent window is formed at edges of each of the red, green, and blue unit pixels. The method of claim 1, wherein the first substrate and the second substrate An electrophoretic display device, characterized in that formed on a plate having flexibility. According to claim 1, A pixel electrode electrically connected to the switching transistor; An electrophoretic display device further comprising a common electrode formed on the second substrate. According to claim 1, An off voltage line and an output scan line parallel to the gate line and insulated from the data line; And a power supply line and a signal output line that are parallel to the data line and insulated from the gate line, the off voltage line, and the output scan line. The light sensing unit A light sensing transistor turned on by irradiating light to the channel portion, the input terminal and the control terminal being connected to the power supply line and the off voltage line, respectively; One end is connected to an output terminal of the photosensitive transistor, and the other end is connected to a signal capacitor connected to the off voltage line, an output terminal of the photosensitive transistor, one end of the signal capacitor, and an input terminal are connected. And an output transistor having control terminals connected to the signal output line and the output scan line, respectively.

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