KR20080111966A - Display device - Google Patents

Abstract

A first base substrate, pixel electrodes formed on the first base substrate, a second base substrate facing the first base substrate, color pixels formed on the second base substrate in a one-to-one correspondence with the pixel electrodes, And a common electrode formed on the second base substrate to cover the color pixels. The color pixels are located in an area where a corresponding pixel electrode is formed. According to the display device, it is possible to prevent color mismatch between different color pixels or alignment miss between the first and second base substrates during the manufacturing process.

Description

Display device {DISPLAY APPARATUS}

1 is a plan view illustrating a display device according to an exemplary embodiment of the present invention.

FIG. 2 illustrates an electrophoretic display device according to an exemplary embodiment, which is a cross-sectional view taken along the cutting line I-I ′ of FIG. 1.

3A to 3C are cross-sectional views for describing the orientation of the electrophoretic particles shown in FIG. 2.

4A is a cross-sectional view illustrating an alignment mis margin of the display device illustrated in FIG. 1.

FIG. 4B is a cross-sectional view for describing prevention of color mixing of the display device illustrated in FIG. 1.

FIG. 5 illustrates a liquid crystal display according to another exemplary embodiment, and is a cross-sectional view taken along the line II ′ of FIG. 1.

* Description of the symbols for the main parts of the drawings *

100-1st display board 200-2nd display board

220-Color filter layer 300-Electrophoretic layer

600-Liquid Crystal Layer DL-Data Line

GL-Gate Line

PA1 to PA3-first to third pixel areas

The present invention relates to a display device, and more particularly, to a display device capable of improving display characteristics.

In general, a display device receives an image signal and displays an image, and includes a cathode ray tube display device, a liquid crystal display, an electrophoretic display, and the like.

The cathode ray tube display device includes a vacuum tube therein, and emits an electron beam from an electron gun to display an image. The cathode ray tube display device must have a sufficient distance for the electron beam to rotate, and thus has a disadvantage of being thick and heavy.

The liquid crystal display displays an image using a characteristic in which the alignment direction of liquid crystal molecules is changed by an electric field, and the electrophoretic display uses an electrophoretic phenomenon in which charged particles move by an electric field. Display the video. Liquid crystal displays and electrophoretic displays are thinner and lighter than cathode ray tube displays. In particular, since the electrophoretic labeling device is a reflective display device that displays an image using external light, there is no need to provide a separate light source.

The liquid crystal display and the electrophoretic display include an array substrate and a color filter substrate coupled to the array substrate. The array substrate includes pixel electrodes arranged in a matrix and thin film transistors that respectively switch data voltages applied to the pixel electrodes. The color filter substrate includes color pixels corresponding to the pixel electrodes one-to-one and a common electrode facing the pixel electrodes. An electric field is formed between the array substrate and the color filter substrate by the potential difference between the pixel electrode and the common electrode.

In the liquid crystal display and the electrophoretic display as described above, misalignment may occur between the array substrate and the color filter substrate during the manufacturing process, or the display characteristics may be degraded by mixing between different color pixels.

An object of the present invention is to provide a display device capable of improving display characteristics.

A display device according to an exemplary embodiment of the present invention for achieving the above object includes a first base substrate, pixel electrodes, a second base substrate, color pixels, and a common electrode. The pixel electrodes are formed on the first base substrate. The second base substrate faces the first base substrate. The color pixels are formed on the second base substrate in a one-to-one correspondence with the pixel electrodes, and are located in an area where a corresponding pixel electrode is formed on a plane. The common electrode is formed on the second base substrate to cover the color pixels.

Hereinafter, with reference to the accompanying drawings, it will be described in detail the present invention.

1 is a plan view illustrating a display device according to an exemplary embodiment of the present invention. FIG. 2 illustrates an electrophoretic display device according to an exemplary embodiment, which is a cross-sectional view taken along the cutting line I-I ′ of FIG. 1.

1 and 2, an electrophoretic display device may include a first display substrate 100, a second display substrate 200 facing the first display substrate 100, and a first display substrate 100. It includes an electrophoretic layer 300 interposed between the second display substrate 200.

The first display substrate 100 includes a first base substrate 110, a plurality of gate lines GL, a plurality of data lines DL, thin film transistors 120, and pixel electrodes 130.

The first base substrate 110 has a plurality of pixel regions defined in an array form. However, FIG. 1 illustrates only the first to third pixel areas PA1 to PA3 among the plurality of pixel areas. The first to third pixel areas PA1 to PA3 are sequentially arranged in the first direction D1 to form one dot area DTA.

The plurality of gate lines GL is formed on an upper surface of the base substrate 110 and extends in the first direction D1. The plurality of data lines DL extend in a second direction D2 orthogonal to the first direction D1, are insulated from and cross the plurality of gate lines GL, and the first through third lines. The pixel areas PA1 to PA3 are defined. The plurality of gate lines GL receives a gate signal and provides the gate signals to the thin film transistors 120, respectively, and the plurality of data lines DL receives a data signal and provides the gate signals to the thin film transistors 120, respectively. do.

The thin film transistors 120 and the pixel electrodes 130 are provided in the first to third pixel areas PA1 to PA3, respectively. The thin film transistors 120 are sequentially formed on the gate electrode 121 and the gate electrode 121 branched from one of the corresponding gate lines among the plurality of gate lines GL. And an ohmic contact layer (not shown), a source electrode 122 formed on an upper surface of the ohmic contact layer branched from one of the plurality of data lines DL, and an upper surface of the ohmic contact layer. Each of the drain electrodes 123 is formed. The pixel electrodes 130 are electrically connected to the drain electrodes 123 provided in the corresponding pixel areas of the first to third pixel areas PA1 to PA3. The thin film transistors 120 are turned on by receiving a gate-on signal from the corresponding gate line, and the turned-on thin film transistors 120 receive a data signal from the corresponding data line to correspond to the corresponding gate line. The pixel electrode is provided. As a result, a data voltage is applied to the corresponding pixel electrode.

The first display substrate 100 further includes a gate insulating layer 141, a passivation layer 142, and an organic insulating layer 143. The gate insulating layer 141 is formed on the first base substrate 110 to cover the gate lines GL and the gate electrode 121. The passivation layer 142 and the organic insulating layer 143 are formed on the gate insulating layer 141 to cover the data lines DL and the thin film transistors 120. The organic insulating layer 160 may be formed of a photosensitive acrylic resin, and may be spaced apart from the data lines DL and the pixel electrodes 130 by a predetermined distance to planarize an upper surface of the array substrate 100.

In addition, the passivation layer 142 and the organic insulating layer 143 have a contact hole CH exposing the drain electrode 123. The pixel electrodes 130 are formed on the top surface of the organic insulating layer 143 and are electrically connected to the drain electrode 123 through the contact hole CH.

The second display substrate 200 is provided on the first display substrate 100. The second display substrate 200 may include a second base substrate 210 facing the first base substrate 110, a color filter layer 220 formed on the second base substrate 210, and a common electrode 230. Include. In one embodiment of the present invention, the second base substrate 210 is made of a flexible material such as polyethylene terephthalate (PET). The common electrode 230 faces the pixel electrodes 130 and receives a common voltage. Therefore, an electric field is formed between the common electrode 230 and the pixel electrodes 130 by a potential difference between the common voltage and the data voltage. In an example of the present invention, the pixel electrodes 130 and the common electrode 230 are made of a transparent conductive material such as indium zinc oxide (IZO) or indium tin oxide (ITO).

An electrophoretic layer 300 including a plurality of electrophoretic particles is interposed between the pixel electrodes 130 of the first display substrate 100 and the common electrode 230 of the second display substrate 200. do. The plurality of electrophoretic particles include white particles 312 and black particles 313 charged with charges having different polarities. The black particles 313 and the white particles 312 move in accordance with an electric field formed between the pixel electrodes 130 and the common electrode 230 to display the gray level of the pixel area. The movement of the plurality of electrophoretic particles will be described in detail later with reference to FIGS. 3A to 3C.

The electrophoretic display device further includes an adhesive member 400. The adhesive member 400 is interposed between the electrophoretic layer 300 and the first display substrate 100 to attach the electrophoretic layer 300 to the first display substrate 100. In an example of the present invention, the electrophoretic layer 300 may be formed integrally with the second display substrate 200 to be formed of one film.

The color filter layer 220 is formed on the second base substrate 210 in a one-to-one correspondence with the pixel electrodes 130 and includes color pixels partially covering the corresponding pixel electrode 130. As illustrated in FIG. 1, the color pixels are located inside a region where the pixel electrodes 130 are formed when viewed in plan view. Preferably, the color pixels are located at the center of the region where the pixel electrodes 130 are formed. As such, each of the color pixels is completely covered by a corresponding pixel electrode.

The color pixels include red, green, and blue color pixels 221, 222, and 223 that express color using light reflected from the white particles 312. The red, green, and blue color pixels 221, 222, and 223 are formed on the second base substrate 210 in a one-to-one correspondence with the first to third pixel areas PA1 to PA3. The red, green, and blue color pixels 221, 222, and 223 are formed using photoresists containing red, green, and blue pigments, respectively.

In one embodiment of the present invention, the red color pixel 221 is formed in the first pixel area PA1, the green color pixel 222 is formed in the second pixel area PA2, and the blue color is formed. The pixel 223 is formed in the third pixel area PA3. Accordingly, red, green, and blue colors are respectively expressed in the first to third pixel areas PA1 to PA3 according to the grayscale values of the first to third pixel areas PA1 to PA3. Meanwhile, in the regions in which the red, green, and blue color pixels 221, 222, and 223 are not formed among the first to third pixel regions PA1 to PA3, the first to third pixel regions PA1 to PA3. The white or black color is expressed according to each gray level value of).

The red, green, and blue color pixels 221, 222, and 223 extend in the second direction D2 within the corresponding pixel electrode. Meanwhile, the second display substrate 200 is formed on the second base substrate 210 to cover the color pixels, and reduces the step difference between an area where the color pixels are provided and an area where the color pixels are not provided. An overcoat layer 240 is further included. The overcoat layer 240 is formed on the entire surface of the second base substrate 210, and the common electrode 230 is formed on the overcoat layer 240 with a uniform thickness.

3A to 3C are cross-sectional views for describing the orientation of the electrophoretic particles shown in FIG. 2.

Referring to FIG. 3A, an electrophoretic layer 300 is interposed between the pixel electrode 130 and the common electrode 230. In the embodiment of the present invention, the electrophoretic layer 300 is composed of a plurality of microcapsules 310 having a spherical shape, each microcapsule 310 is a dispersion medium 311 made of a transparent insulating liquid, the dispersion medium And a plurality of electrophoretic particles dispersed in 311. The plurality of electrophoretic particles consist of white particles and black particles 312 and 313. The white particles and the black particles 312 and 313 are charged with electric charges having different polarities.

A surfactant is added to the dispersion medium 311, and the specific gravity of the dispersion medium 311 and the white particles and the black particles 312 and 313 is almost the same to prevent precipitation by gravity. In addition, the dispersion medium 311 prevents the pulling of the white particles and the black particles 312 and 313 or the aggregation of the white particles and the black particles 312 and 313 into a large mass. .

In one embodiment of the present invention, the white particles 312 are charged with a positive charge and are made of a material such as titanium dioxide (TiO ₂ ) to have a white color. The black particles 313 are charged with a negative charge and are made of carbon powder such as carbon black to have a black color.

In the state where no electric field is formed between the pixel electrode 130 and the common electrode 230, the white particles and the black particles 312 and 313 do not have directivity, and thus the pixel electrode 130 Randomly provided between the common electrode 230 and.

Subsequently, as illustrated in FIG. 3B, when a data voltage having positive polarity (+) with respect to the common voltage applied to the common electrode 230 is applied to the pixel electrode 130, the pixel electrode is caused by a voltage difference. An electric field is formed at 130 and the common electrode 230.

In this case, the white particles 312 charged with the positive charge move toward the common electrode 230, and the black particles 313 charged with the negative charge correspond to the pixel electrode ( 130) go to the side. As such, when an electric field having positive polarity (+) is formed between the pixel electrode 130 and the common electrode 230, the white gray level is displayed in the pixel area.

As described above, when the white gray scale is displayed, light incident through the common electrode 230 is reflected by the white particles 312, and the reflected light is again reflected through the common electrode 230. By exiting, the user can visually recognize an image of white gradation. In addition, when a color pixel is provided on the common electrode 230 to which the reflected light is emitted again, the color of the color pixel is expressed, so that the user may recognize the expressed color.

As illustrated in FIG. 3C, when a data voltage having negative polarity (−) is applied to the pixel electrode 130 with respect to the common voltage applied to the common electrode 230, the pixel electrode 130 and the common voltage are applied to the pixel electrode 130. An electric field is formed in the electrode 230.

In this case, the white particles 312 charged with the positive charge move toward the pixel electrode 130, and the black particles 313 charged with the negative charge correspond to the common electrode ( 230) move to the side. As such, when an electric field having a negative polarity (−) is formed between the pixel electrode 130 and the common electrode 230, a black gray level is displayed in the pixel area.

As described above, when the black gradation is displayed, light incident through the common electrode 230 is absorbed by the black particles 313 so that light is hardly emitted through the common electrode 230. . Therefore, the color of the color pixels provided on the common electrode 230 is not expressed, and the user may recognize the image of the black gradation.

4A is a cross-sectional view illustrating an alignment miss margin of the display device illustrated in FIG. 1.

Referring to FIG. 4A, when an alignment miss occurs when the first display substrate 100 and the second display substrate 200 are bonded to each other, the second display substrate 200 may become the first display substrate 100. The first display substrate 100 is bonded to the first display substrate 100 by moving a predetermined distance from the position corresponding to the first display substrate 100. In the electrophoretic display, an image is normally displayed only when alignment is performed between the color pixels and the corresponding pixel electrode. Therefore, when the misalignment between the first display substrate 100 and the second display substrate 200 causes an alignment error between the color pixels and the pixel electrodes 130, the image is abnormal in the electrophoretic display device. Is displayed.

However, according to the present exemplary embodiment, since the color pixels are formed in the center of the region where the corresponding pixel electrode is formed and covered with the pixel electrode, even if an alignment miss occurs within a predetermined range, the pixel pixel corresponds to the pixel electrode. It does not go out of scope. As a result, an abnormal image is prevented from being displayed due to an alignment error between the color pixels and the pixel electrodes 130.

FIG. 4B is a cross-sectional view for describing prevention of color mixing of the display device illustrated in FIG. 1.

Referring to FIG. 4B, the incident light 10 incident from the outside during the operation of the electrophoretic display device is reflected from the surface of the white particles 312 and is emitted to the outside. However, when the color is different in the region of the color pixel in which the incident light 10 is incident and the region of the color pixel in which the incident light 10 is incident, display quality may be deteriorated due to mixed color. For example, when the incident light 10 in the red pixel 221 region exits to the neighboring green pixel 222 region, mixed color between red and green may occur.

However, according to the present embodiment, since the color pixels are formed in the center of the region where the corresponding pixel electrode is formed, a sufficient separation distance between the different pixels can be secured, so that the mixed color is prevented. For example, even though the incident light 10 in the red pixel 221 region exits from the red pixel 221 region, the emitted light 11 does not invade the neighboring green pixel 222 region. In addition, the output light 12 corresponding to the incident light 10 in the area between the blue and green color pixels 222 and 223 is emitted to the area as the green color pixel 223, and no mixing between blue and green colors occurs.

FIG. 5 illustrates a liquid crystal display according to another exemplary embodiment, and is a cross-sectional view taken along the line II ′ of FIG. 1.

1 and 5, the liquid crystal display according to the present exemplary embodiment includes a first display substrate 100, a second display substrate 200 facing the first display substrate 100, and the first display substrate. The liquid crystal layer 600 is interposed between the second display substrate 200 and the second display substrate 200. The liquid crystal display device has a structure similar to the electrophoretic display device shown in FIG. 2 except for the liquid crystal layer 600. Therefore, detailed descriptions of the first and second display substrates 100 and 200 will be omitted, and components different from those of the electrophoretic display device will be described.

The first display substrate 100 may include a first base substrate 110, a plurality of gate lines GL, a plurality of data lines DL, thin film transistors 120, pixel electrodes 130, and a gate insulating film. 141, a protective film 142, and an organic insulating film 143.

The second display substrate 200 includes a second base substrate 210, a color filter layer 220, a common electrode 230, and an overcoat layer 240, and is coupled to face the first display substrate 100. do. The second display substrate 200 is formed on the second base substrate 210 in correspondence with the region where the gate lines GL, the data lines DL, and the thin film transistors 120 are formed. The matrix 250 further includes. The black mattress 250 may be made of a light blocking material to block light leakage from the periphery of each of the first to third pixel areas PA1 to PA3.

The liquid crystal display device operates in a transmissive or reflective mode. The backlight unit may further include a backlight unit (not shown) provided on a rear surface of the first display substrate 100 to provide light to the first display substrate 100. In the reflective operation, the first display substrate 100 further includes a reflective electrode and operates in the same manner as the electrophoretic display device.

The liquid crystal layer 600 is interposed between the first and second display substrates 100 and 200. The arrangement direction of the liquid crystal molecules 610 of the liquid crystal layer 600 is changed according to the potential difference between the common electrode 230 and the pixel electrodes 130, and the light transmittance is changed according to the arrangement direction. The color pixels express each color using the light.

In the present exemplary embodiment, the liquid crystal display is driven in a normally white mode, and the liquid crystal layer 600 is formed of TN (Twist Nematic) liquid crystal molecules 610 having positive dielectric anisotropy. Is done.

In the off state of the liquid crystal display, the liquid crystal molecules 321 are horizontally aligned with respect to the first and second display substrates 100 and 200. When the liquid crystal molecules 610 are arranged in parallel with the first and second display substrates 100 and 200, the light provided to the liquid crystal display passes through the liquid crystal molecules 610 to generate a phase change. The liquid crystal display maintains a white state.

When an electric field is formed between the pixel electrodes 130 and the common electrode 230, the liquid crystal molecules 610 are arranged in a direction parallel to the electric field. Thus, the liquid crystal molecules 610 are arranged in a direction perpendicular to the first and second display substrates 100 and 200. In this state, the light provided to the liquid crystal display is not emitted to the outside, and the liquid crystal display is in a black state.

According to the above embodiments, it is possible to prevent color mismatch between different color pixels or alignment miss between the first and second base substrates during the manufacturing process. Although described with reference to the embodiments above, those skilled in the art will understand that the present invention can be variously modified and changed without departing from the spirit and scope of the invention as set forth in the claims below. Could be.

Claims (7)

A first base substrate; Pixel electrodes formed on the first base substrate; A second base substrate facing the first base substrate; Color pixels formed on the second base substrate in a one-to-one correspondence with the pixel electrodes and positioned inside a region where a corresponding pixel electrode is formed on a plane; And And a common electrode formed on the second base substrate to cover the color pixels. The method of claim 1, And each of the color pixels is positioned at a center portion of a region where a corresponding pixel electrode is formed. The method of claim 1, And the color pixels correspond to the pixel electrodes one-to-one, and include red, green, and blue pixels alternately disposed. The method of claim 1, And a plurality of electrophoretic particles, the electrophoretic layer interposed between the pixel electrode and the common electrode. The method of claim 4, wherein The plurality of electrophoretic particles include a plurality of black particles and a plurality of white particles having different polarities. The method of claim 1, And a liquid crystal layer interposed between the common electrode and the pixel electrode. The method of claim 1, And an overcoat layer formed between the color pixels and the common electrode.

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