KR20070045379A - Liquid crystal display and fabricating method thereof - Google Patents

Abstract

The present invention relates to a liquid crystal display device and a method of manufacturing the same that the manufacturing process is simple, the cost can be reduced and the display quality is improved.

According to an exemplary embodiment of the present invention, a frame is driven by dividing a plurality of subframes, and a first substrate and a second substrate are bonded to each other with a liquid crystal interposed therebetween, wherein the first substrate includes a common electrode formed on an insulating substrate; A black matrix formed on a common electrode, and a column spacer formed on the black matrix and formed simultaneously with the black matrix on the black matrix, and a method for manufacturing the same.

Partial Exposure Mask, Black Matrix, Column Spacer, Liquid Crystal, OCB, LED

Description

Liquid crystal display and its manufacturing method {LIQUID CRYSTAL DISPLAY AND FABRICATING METHOD THEREOF}

1 is a view for schematically explaining a color sequential driving method according to an embodiment of the present invention.

2 is a cross-sectional view schematically illustrating an OSC mode according to an exemplary embodiment of the present invention.

3 is a plan view showing a first substrate according to an embodiment of the present invention.

4 is a cross-sectional view taken along line IV-IV 'of FIG.

5A to 5D are cross-sectional views illustrating a method of manufacturing a first substrate according to an embodiment of the present invention.

<Code Description of Main Parts of Drawing>

10: liquid crystal display device 20: first substrate

30: first insulating substrate 40: common electrode

50: black matrix 60: column spacer

70: polymer resin 80: semi-permeable mask

90: light blocking layer 100: transflective layer

110: second substrate 120: second insulating substrate

130 pixel electrode 140 OCs type liquid crystal

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a method for manufacturing the same, and more particularly, to a liquid crystal display device and a method for manufacturing the same, wherein the manufacturing process is simple, the cost can be reduced, and the display quality is improved.

Liquid crystal displays are the most widely used among flat panel displays, and have recently been used in televisions and the like. For this reason, there is an increasing demand for display quality such as fast response speed, high color reproducibility, and high contrast suitable for video.

Such liquid crystal display devices can be classified into various types according to their modes. The most widely used liquid crystal display devices are twisted nematic (TN) type liquid crystal display devices.

Generally, a twisted nematic liquid crystal display device includes a backlight unit for providing white light and a liquid crystal display panel for displaying an image using white light from the backlight unit.

The backlight unit includes a CCFL (Cold Cathode Fluorescent Lamp) for generating and emitting white light, a light guide plate for guiding the white light emitted from the CCF to a liquid crystal display panel, and a light guide plate positioned under the light guide plate to return white light emitted from the light guide plate. It contains a reflective sheet to return to.

The liquid crystal display panel includes a twisted nematic liquid crystal interposed between the first and second substrates facing each other and the first and second substrates.

The first substrate divides the pixels on the first insulating substrate and forms a black matrix formed to prevent light leakage, a color filter formed on the pixels partitioned by the black matrix to realize various colors through additive mixed color of transmitted light by transmitting white light, An overcoat formed to cover the color filter for good step coverage of the common electrode, and a common electrode formed on the overcoat to apply a common voltage to the twisted nematic liquid crystal.

In this case, the color filter is generally coated, exposed and developed a photoresist containing a specific color pigment, and then subjected to a post-baking (Post Bake) to form a color filter of a specific color, the process is repeated to different colors It is formed through the pigment dispersion method of sequentially forming the color filter of.

However, the pigment dispersion method is complicated in that the process of coating, exposing, developing, and post-baking the red, green, and blue photoresists must proceed. In addition, since each photoresist is applied by spin coating, most of them are removed in the development process, and thus, the cost of manufacturing the first substrate is increased due to the large material loss. In addition, since the light passing through the color filter due to the color pigment is actually only a few ten% (for example, 33%), the loss of light is large. For this reason, in order to increase the luminance of the twisted nematic liquid crystal display device, the luminance of the CCF should be increased, thereby increasing the power consumption.

And even if the overcoat is formed to cover the color filter, the flatness in the pixel is not so good.

The first substrate further includes a column spacer for allowing the first substrate to maintain a predetermined gap, that is, a cell gap, with the second substrate. Since the column spacer is manufactured using a separate mask for the column spacer on the common electrode, the manufacturing cost of the first substrate is increased and the manufacturing process is complicated.

The second substrate includes a gate line and a data line formed to cross each other on the second insulating substrate, a thin film transistor formed at an intersection thereof, and a pixel electrode connected to the thin film transistor to apply a pixel voltage to the twisted nematic liquid crystal. .

The twisted nematic liquid crystal has a specific orientation in the arrangement and rotates by the pixel voltage of the pixel electrode and the common voltage of the common electrode to adjust the light transmittance. That is, the twisted nematic liquid crystal is twisted 90 degrees when no electric field is applied, and when the electric field is applied, the twisted nematic liquid crystal is arranged perpendicularly to the pixel electrode and the common electrode to adjust the light transmittance.

However, the twisted nematic liquid crystal display has a problem in that the response speed is slow due to the arrangement of the twisted nematic liquid crystal and the physical properties (eg, elastic modulus) of the twisted nematic liquid crystal itself. For this reason, various problems, such as an afterimage, arise and are not suitable for moving pictures.

Accordingly, the technical problem to be achieved by the present invention is to provide a liquid crystal display device and a method of manufacturing the same that the manufacturing process is simple, the cost can be reduced and the display quality is improved.

In order to achieve the above object, the present invention provides a liquid crystal display device in which one frame is divided into a plurality of subframes and a first substrate and a second substrate are bonded together with a liquid crystal interposed therebetween, wherein the first substrate is formed on an insulating substrate. It provides a liquid crystal display comprising a common electrode formed, a black matrix formed on the common electrode, and a column spacer formed on the black matrix simultaneously with the black matrix of the same material as the black matrix.

The liquid crystal is characterized in that the liquid crystal for the OSC mode.

The apparatus may further include red, green, and blue light sources positioned on the rear surface of the second substrate and sequentially generating red, green, and blue light during one frame.

Herein, the red, green, and blue light sources are red, green, and blue LEDs, respectively.

In order to achieve the above object, the present invention provides a method of manufacturing a liquid crystal display device, in which one frame is divided into a plurality of subframes, comprising: a common electrode formed on a first insulating substrate, a black matrix formed on the common electrode; Providing a first substrate including a column spacer formed on the black matrix, preparing a second substrate including a pixel electrode formed on a second insulating substrate, and forming the first and second substrates. It provides a method for manufacturing a liquid crystal display device comprising the step of bonding the liquid crystal between.

The preparing of the first substrate may include forming a common electrode on the first insulating substrate, and simultaneously forming the black matrix and the column spacer on the common electrode with the same material. .

The forming of the black matrix and the column spacer simultaneously using the same material may include applying an opaque polymer resin on the common electrode, exposing the polymer resin using a partial exposure mask, and And developing the resin.

On the other hand, the liquid crystal is characterized in that the liquid crystal for the OSC mode.

And providing a red, green, and blue light source that sequentially generates red, green, and blue light for one frame on the back surface of the second substrate.

The providing of the red, green, and blue light sources on the rear surface of the second substrate may include providing the red, green, and blue LEDs on the rear surface of the second substrate.

Other objects and features of the present invention in addition to the above object will become apparent from the description of the embodiments with reference to the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a view for schematically explaining a color sequential driving method according to an embodiment of the present invention.

Referring to FIG. 1, a liquid crystal display according to an exemplary embodiment of the present invention uses a color sequential LED using a light emitting diode (LED), unlike a conventional liquid crystal display device that uses CFCs and color filters to implement colors. (Color Sequential) Implement color by adopting driving method.

The color sequential driving method is a method of displaying an image of a desired color by lighting red, green, and blue LEDs at time intervals without using a color filter to adjust light transmittance through liquid crystals on the red, green, and blue LEDs. Therefore, it is not necessary to form an expensive color filter, thereby reducing the cost. In addition, unlike the conventional twisted nematic liquid crystal display, which requires three subpixels of red, green, and blue per pixel to realize various colors, the color may be implemented using only one subpixel. That is, the liquid crystal display device according to the embodiment of the present invention has advantages such as high resolution, high light efficiency, low power consumption, high color reproduction rate, and low manufacturing cost due to the simple structure of '1 pixel = 1 subpixel'. Meanwhile, other light sources other than red, green, and blue LEDs may be used to generate red, green, and blue light.

In this color sequential driving method, in order to eliminate the natural expression of color, that is, the visibility such as flickering, the time period of reproducing the color should be less than the resolution of the human eye. In general, the frame frequency of an image to be used is set to 60 Hz in consideration of green having the highest flicker visibility, and the period corresponds to 1/60 second. That is, in one frame of 1/60 second, the red, green, and blue LEDs are turned on, respectively, and the image is represented by adjusting the brightness of the red, green, and blue light with the liquid crystal.

In this case, when a section in which red, green, and blue LEDs are turned on, respectively, is represented as a subframe, one frame includes three subframes, that is, red, green, and blue subframes (R, G, and B). Each of the green and blue subframes R, G, and B has a period of 1 / (60 * 3) = 5.56 msec. Here, each of the red, green, and blue subframes R, G, and B has an addressing time Ta, which is a time required for charging the entire pixel electrodes of the second substrate of the liquid crystal display, and a time waiting for a change in polarization characteristics of the liquid crystal. The liquid crystal response time Tb, the red, green, and blue LEDs are turned on, respectively, and the lighting time Tc is a time for generating actual light.

By the way, the addressing time Ta becomes longer for a liquid crystal display device having a higher resolution, and the lighting time Tc becomes longer for a liquid crystal display device having a higher luminance. In each case, when the liquid crystal response time Tb is long, a sufficient addressing time Ta or a sufficient lighting time Tc cannot be secured, so that gray scale expression is impossible or luminance is low. Therefore, it is necessary to have a short liquid crystal response time Tc while ensuring a sufficient addressing time Ta and a sufficient lighting time Tc. However, in the conventional twisted nematic liquid crystal display device, since the response time is about 20 msec, it is almost impossible to apply the color sequential driving method.

Therefore, in the exemplary embodiment of the present invention, an optically compensated birefringent (OCB) mode is used as the liquid crystal mode.

2 is a cross-sectional view schematically illustrating an OSC mode according to an exemplary embodiment of the present invention.

Referring to FIG. 2, in the liquid crystal display device 10 having the OSC mode in accordance with an embodiment of the present invention, the OSC liquid crystal 140 is interposed between the first substrate 20 and the second substrate 110. The OSC liquid crystal 140 has a splay state when an electric field is not formed between the common electrode 40 on the first insulating substrate 30 and the pixel electrode 130 on the second insulating substrate 120. The bent state is formed when an electric field is formed between the common electrode 40 on the first insulating substrate 30 and the pixel electrode 130 on the second insulating substrate 120. That is, the OSC liquid crystal 140 adjusts the sizes of the red, green, and blue light from the red, green, and blue LEDs located on the rear surface of the second substrate 110 by changing the arrangement state. In addition, the OSC liquid crystal 140 is bent in the open state by a voltage of approximately several V (for example, 1.8 V or less), thereby further reducing power consumption required for driving the OSC liquid crystal 140 and providing a fast response speed. Implement

Meanwhile, the first substrate 20 should include a column spacer to secure a space in which the OCCB liquid crystal 140 may be interposed between the first substrate 20 and the second substrate 110 and to form a cell gap. This first substrate 20 will be described in more detail with reference to FIGS. 3 and 4.

3 is a plan view illustrating a first substrate according to an exemplary embodiment of the present invention, and FIG. 4 is a cross-sectional view taken along line IV-IV ′ of FIG. 3.

3 and 4, the first substrate 20 according to the embodiment of the present invention is formed on the common electrode 40 and the common electrode 40 formed on the first insulating substrate 30, and the pixel is formed. It is formed on the separating black matrix 50, the black matrix 50 and includes a column spacer 60 for maintaining the cell gap.

The common electrode 40 is formed of a transparent conductive metal such as ITO or IZO, and applies the common voltage of the common voltage generator to the OSC liquid crystal. To this end, the common electrode 40 receives a common voltage through a short formed between the common electrode line of the second substrate and the first substrate 20 and the second substrate. Here, the thickness of the common electrode 40 is preferably 500 kPa to 2000 kPa. More preferably, the thickness of the common electrode 40 is 800 kPa to 1200 kPa.

The black matrix 50 is formed in the form of a matrix on the common electrode 40 so as to distinguish the pixels, and overlaps with the gate line and data line of the second substrate and the channel of the thin film transistor of the second substrate. Since the black matrix 50 is formed on the common electrode 40, there is no need to separately form an overcoat. In addition, since the common electrode 40 is formed on the first insulating substrate 30, the flatness in the pixel is greatly improved.

The black matrix 50 blocks the transmitted light generated by the undesired OCI ratio liquid crystal array to improve the contrast of the liquid crystal display device and prevents light leakage current of the thin film transistor by blocking direct light irradiation to the channel of the thin film transistor. To this end, the black matrix 50 is formed of an opaque polymer resin or the like. Here, it is preferable that the thickness of the black matrix 50 is 0.5 micrometer-2.5 micrometers. The thickness of the more preferable black matrix 50 is 1 micrometer-2 micrometers. For example, when the thickness of the black matrix 50 is 1.5 µm, 4.5 may be obtained as an optical density (OD) value. This value is sufficient for light leakage prevention and high contrast. Here, the optical density refers to the degree of the intensity I1 of the transmitted light with respect to the intensity I2 of the incident light as shown in [Equation 1].

The column spacer 60 is formed on the black matrix 50 simultaneously with the black matrix 60 in the same material as the black matrix 50. The column spacer 60 maintains the cell gap between the first substrate 20 and the second substrate. The column spacer 60 may be formed to have the same number of pixels and smaller than the number of pixels. Here, the thickness of the column spacer 60 is preferably 2 μm to 5.5 μm. The thickness of the more preferable column spacer 60 is 2.5 micrometers-4 micrometers.

On the other hand, it is not necessary to form a color filter on the first insulating substrate 30 to implement the color. This is because colors are implemented by using red, green, and blue LEDs positioned on the rear surface of the second substrate.

Such a first substrate is manufactured through a manufacturing method as shown in FIGS. 5A to 5D.

Referring to FIG. 5A, the first substrate according to the embodiment of the present invention first forms the common electrode 40 on the first insulating substrate 30.

Specifically, the common electrode 40 is formed by depositing a transparent conductive metal such as ITO or IZO to a thickness of several hundreds to thousands of micrometers by using a method such as sputtering on the first insulating substrate 30 such as glass or plastic. Form. For example, the common electrode 40 is formed by depositing 1000 ITO on the first insulating substrate 30.

Referring to FIG. 5B, an opaque polymer resin 70 or the like is coated on the common electrode 40.

Specifically, a polymer resin 70 having negative photosensitivity or the like is coated on the common electrode 40 with a thickness of several μm. For example, the opaque polymer resin 70 is applied to a thickness of 4.5 mu m.

Referring to FIG. 5C, after the opaque polymer resin 70 is coated on the common electrode 40, the polymer resin 70 is exposed using a semi-transmissive mask 80, which is a kind of a partial exposure mask. Here, a slit mask can be used as the partial exposure mask.

Specifically, the semi-transmissive mask 80 includes a light blocking layer 90 and a semi-transmissive layer 100. The light blocking layer 90 completely blocks light and the semi-transmissive layer 100 transmits a part of light. . When the polymer resin 70 is exposed using the semi-permeable mask 80, the polymer resin 70 is completely blocked by the light blocking layer 90 so that the polymer resin 70 does not remain at all after development. (L), since the light is not blocked at all, the area (M) and the semi-transmissive layer 100 where the black matrix 50 and the column spacer 60 are to be formed at the same time after the development are partially transmitted to the black matrix after development. 50 consists of a region N to be formed.

Referring to FIG. 5D, the polymer resin is exposed and developed to simultaneously form the black matrix 50 and the column spacer 60.

Specifically, when the polymer resin is exposed using a semi-permeable mask and then developed using a developer, an area where no polymer resin remains is formed, and the black matrix 50 and the column spacer 60 are simultaneously formed.

The above-described liquid crystal display of the present invention and a method of manufacturing the same include a first substrate including a black matrix and a column spacer formed on a common electrode on the first insulating substrate. Since the black matrix and the column spacer are formed of the same material at the same time, the manufacturing process can be simplified, light leakage prevention, and high contrast can be obtained. In addition, since there is no need to form an overcoat and a common electrode is formed on the first insulating substrate, the flatness in the pixel is high. In addition, since LEDs are used instead of CFCs and color filters to implement colors, color filters do not need to be formed on the first insulating substrate. For this reason, the manufacturing process can be simplified and the cost of the liquid crystal display device can be lowered. In addition, since LEDs are used, high light efficiency, low power consumption, and high color reproducibility can be obtained. In addition, since the OSC liquid crystal is used as the liquid crystal, a fast response speed can be obtained.

In the detailed description of the present invention described above with reference to the preferred embodiment of the present invention, those skilled in the art or those skilled in the art having ordinary knowledge of the present invention described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the spirit and scope of the art.

Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification but should be defined by the claims.

Claims (10)

In a liquid crystal display device in which one frame is driven by being divided into a plurality of subframes, and a first substrate and a second substrate are bonded together with a liquid crystal interposed therebetween. The first substrate includes a common electrode formed on the insulating substrate; A black matrix formed on the common electrode; And a column spacer formed on the black matrix simultaneously with the black matrix on the black matrix. The method of claim 1, And said liquid crystal is a liquid crystal for an OSC mode. The method of claim 1, And a red, green, and blue light source positioned on the rear surface of the second substrate and sequentially generating red, green, and blue light for one frame. The method of claim 3, The red, green, and blue light sources are red, green, and blue LEDs, respectively. In the method of manufacturing a liquid crystal display device in which one frame is divided into a plurality of subframes, Providing a first substrate including a common electrode formed on a first insulating substrate, a black matrix formed on the common electrode, and a column spacer formed on the black matrix; Providing a second substrate including a pixel electrode formed on the second insulating substrate; And bonding the first and second substrates together with a liquid crystal interposed therebetween. The method of claim 5, Preparing the first substrate Forming a common electrode on the first insulating substrate; And simultaneously forming the black matrix and the column spacer on the common electrode of the same material. The method of claim 6, Simultaneously forming the black matrix and the column spacer with the same material Coating an opaque polymer resin on the common electrode; Exposing the polymer resin using a partial exposure mask; A method of manufacturing a liquid crystal display device, comprising developing the polymer resin. The method of claim 5, The liquid crystal is a liquid crystal display device, characterized in that the liquid crystal for the OSC mode. The method of claim 5, And providing a red, green, and blue light source that sequentially generates red, green, and blue light for one frame on the back surface of the second substrate. The method of claim 9, The step of providing the red, green, blue light source on the back of the second substrate And providing red, green, and blue LEDs on the back surface of the second substrate.

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