KR20090095746A - Apparatus and method for attaching polarizer film on LCD panel - Google Patents

Abstract

A polarizer attaching method for adhering first/second polarizer in order to be optimized according to each liquid crystal panel is provided to improve contrast ratio by maximizing black brightness. A liquid crystal panel(110) is absorbed to an upper suction plate. A first polarizer(116) is absorbed to a lower part adsorption plate(170). A second polarizer(118) is interposed and a brightness measurer is located. The light is irradiated in the liquid crystal panel in which the first polarizer is adhered and the second polarizer. The lower part adsorption plate is rotated based on the origin in the first angular range. The brightness measurement measures the luminance of 'the light passing through the second polarizer'.

Description

Application method for attaching polarizer to liquid crystal panel {Apparatus and method for attaching polarizer film on LCD panel}

The present invention relates to a polarizing plate attaching method, and more particularly, to a polarizing plate attaching apparatus capable of improving contrast ratio and a polarizing plate attaching method using the same.

Recently, liquid crystal displays have been spotlighted as next generation advanced display devices having low power consumption, good portability, high technology value, and high added value.

Among the liquid crystal display devices, an active matrix liquid crystal display device having a thin film transistor, which is a switching element that can control voltage on and off for each pixel, has the best resolution and video performance. I am getting it.

Referring to FIG. 1, which is an exploded perspective view of a general liquid crystal display device, a structure of the liquid crystal display device will be described. As illustrated, the lower substrate 10 and the array substrate 10 and the upper portion of the lower substrate 10 are interposed therebetween. The color filter substrate 20, which is the substrate 20, has a configuration in which the color filter substrate 20 is face-to-face bonded. The lower substrate 10, the upper substrate 20, and the liquid crystal layer 30 are called liquid crystal cells or liquid crystal panels.

On the other hand, the lower array substrate 10 includes a plurality of gate wirings 14 and data wirings 16 vertically and horizontally arranged on the upper surface of the transparent substrate 12 to define a plurality of pixel regions P. A thin film transistor T is provided at an intersection point of the two wires 14 and 16 and is connected in one-to-one correspondence with the pixel electrode 18 provided in each pixel region P. As shown in FIG.

In addition, the upper color filter substrate 20 facing the array substrate 10 is a rear surface of the transparent substrate 22, and the non-display of the gate wiring 14, the data wiring 16, the thin film transistor T, and the like. A grid-like black matrix 25 is formed around each pixel region P so as to cover an area, and red, green, and blue colors sequentially arranged in order to correspond to each pixel region P in the grid. A color filter layer 26 including filter patterns 26a, 26b, and 26c is formed, and a transparent common electrode 28 is provided over the entire surface of the black matrix 25 and the color filter layer 26.

Although not shown in the drawings, these two substrates 10 and 20 seal along the edges of the two substrates 10 and 20 to prevent leakage of the liquid crystal layer 30 interposed therebetween. In the sealed state, the upper and lower alignment layers which provide reliability in the molecular arrangement direction of the liquid crystal are interposed between the substrates 10 and 20 and the liquid crystal layer 30. The outer surface of 20 is provided with a first polarizing plate (not shown) and a second polarizing plate (not shown) through which light in a specific direction passes. In this case, the optical axes (not shown) of the first polarizing plate (not shown) and the second polarizing plate (not shown) are arranged to be perpendicular to each other.

In addition, a back-light (not shown) is provided on the outer surface of the array substrate 10 to supply light, so that the thin film transistor T is turned on / off by the gate wiring 14. off) signal is sequentially scanned and the image signal of the data line 16 is transferred to the pixel electrode 18 of the selected pixel region P, the liquid crystal molecules are driven by the vertical electric field therebetween. Various images can be displayed by changing the transmittance of light.

2A and 2B schematically illustrate alignment of a liquid crystal cell and a polarizing plate at the time of applying an electric field and before applying the electric field in the conventional LCD.

When power is supplied to the liquid crystal panel 35 of the liquid crystal display device, an electric field is generated between the two substrates 10 and 20, and the liquid crystal molecules 31 in the liquid crystal layer 30 are formed by the upper substrate 20. And move in a direction perpendicular to the lower substrate 10.

The first surface of the upper substrate 20 is attached to the first polarizing plate 41 for transmitting a predetermined light by linearly polarized light, the outer surface of the lower substrate 10 is perpendicular to or parallel to the first polarizing plate 41. A second polarizing plate 45 having an optical axis is attached. In the figure, a liquid crystal cell having optical axes 43 and 47 in a state perpendicular to each other is illustrated.

According to the above structure, the liquid crystal display adjusts the light transmittance to display an image of the screen. However, referring to FIG. 2A, the liquid crystal molecules 31 in the liquid crystal layer 30 vertically receiving the electric field are not aligned at right angles, so that the optical axis 33 of the liquid crystal layer 30 is the first and second optical axes. It is not perpendicular to (43, 47), and as shown in Fig. 2B, even when no electric field is applied, adjacent to the optical axes 43, 47 of the first and second polarizing plates 41, 45, respectively. The long axes 33a and 33b of the positioned liquid crystal molecules 31 do not form a vertical or parallel state.

The liquid crystal has anisotropy in its molecules, and the anisotropy of the liquid crystal layer 30 or film made of the molecule varies depending on the distribution of the liquid crystal layer 30 and the degree of distribution of the tilt angle with respect to the substrate. It is an important factor to change the polarization of light according to the viewing angle.

On the other hand, the first and second polarizing plates 41 and 45 are attached to the upper substrate 20 and the lower substrate 10 such that their optical axes are perpendicular or parallel to each other above and below the liquid crystal layer 30. Accordingly, the intensity of transmitted light is adjusted according to the degree of rotation of the optical axis (hereinafter, referred to as a cell axis) of the liquid crystal layer 30 while the light passes through the liquid crystal layer 30, so that the gray between black and white is gray. (gray) representation is possible.

3A to 3C are cross-sectional views briefly illustrating attaching a polarizing plate to a conventional liquid crystal panel.

First, as shown in FIG. 3A, when the liquid crystal panel 35 is positioned on the lower adsorption plate 51 of the polarizer attaching device, the vision camera 45 or the like operates to determine the position of the liquid crystal panel 35. The lower suction plate 51 of the liquid crystal panel 35 is aligned. At this time, the first polarizer (not shown) attached to the outer surface of the upper substrate 20 of the liquid crystal panel 35 is in a state of being adsorbed by the upper adsorption plate (not shown).

Next, as shown in FIG. 3B, the first polarizing plate 70 is adsorbed to the upper adsorption plate 55, and the liquid crystal panel 35 is adsorbed to the lower adsorption plate 51, thereby contacting these two components. The attachment is made. A plurality of vacuum holes (not shown) are formed in the upper adsorption plate 55 and the lower adsorption plate 51, and the vacuum holes (not shown) are connected to a vacuum device (not shown) to form a first polarizing plate with a vacuum adsorption force. 70 and the liquid crystal panel 35 are fixed to specific working positions of the upper and lower suction plates 55 and 51, respectively. In this case, the upper adsorption plate 55 is adjacent to the attachment roller 57 in an inclined form with respect to the surface of the lower adsorption plate 51 so that the first polarizing plate 70 and the liquid crystal panel 35 can be smoothly attached. Will be located. On the other hand, the lower suction plate 51 is installed so that the surface thereof is perpendicular to the direction of gravity and move forward while passing through the lower portion of the roller (57).

The operation of the polarization attaching device will be described a little further. In the initial setting step, the first polarizing plate 70 adsorbed on the upper adsorption plate 55 is in contact with the liquid crystal panel 35 adsorbed on the lower adsorption plate 51 and the ends thereof. One surface is inserted into the roller 57 in the state.

Thereafter, when the roller 57 is rotated, the first polarizing plate 70 is interposed between the roller 57 and the lower adsorption plate 51 by friction in direct contact between the roller 57 and the first polarizing plate 70. ) And the liquid crystal panel 35 are pulled in and the front adhesive is sequentially formed. In this case, the liquid crystal panel 35 moves together by moving the lower suction plate 51 itself, and the first polarizing plate 70 slides on the surface of the upper suction plate by adjusting the vacuum pressure of a vacuum hole (not shown). As shown, the roller 57 is moved toward the roller 57.

Next, as shown in FIG. 3C, the second polarizing plate 73 is attached to the outer surface of the lower substrate 10. In the case of FIG. 3C, the operation of FIG. 3B is similar to that of FIG. 3B, and the operation thereof is similar.

The upper adsorption plate 55 is movable and adsorbs the liquid crystal panel 35 to which the first polarizing plate 70 is attached in a state perpendicular to the direction of gravity, and the lower adsorption plate 51 is the surface of the upper adsorption plate 55. It is fixed in an inclined form with respect to the second polarizing plate 73, and when the roller 57 is rotated in such a state, it is directly connected between the roller 57 and the second polarizing plate 73. The second polarizing plate 73 and the liquid crystal panel 35 are dragged between the roller 57 and the upper suction plate 55 by friction in contact with each other, so that front adhesion is sequentially performed.

However, when the alignment is performed through the vision camera as an image processing apparatus as described above, and the first and second polarizing plates are attached to the liquid crystal panel in a predetermined direction in this state, as shown in FIG. 4, all liquid crystal panels ( The first and second polarizers 70 (not shown) are attached only in the direction determined collectively with respect to 35.

In this case, in this process, the liquid crystal molecules are rotated by an electric field or due to an alignment error of the alignment layer (not shown), and finally, the cell axis is vertical or horizontal to the first and second polarizing plates 70 (not shown). Small errors may occur with respect to the direction and may be inclined at a predetermined angle. Thus, the optical axis and the cell axis of the first and second polarizing plates 70 (not shown) are not orthogonal or horizontally aligned, thereby making a perfect black. It can't be formed, which causes the contrast to fall.

In this case, the black and white ratios determine the brightness of the screen. In particular, in the black state, the optical axis and the cell axis of the first and second polarizing plates 70 (not shown) may be perpendicular to each other when the electric field is applied. In the case of normal black, when the electric field is not applied, the optical axes of the first and second polarizers 70 (not shown) and the long axes of the liquid crystal molecules in the liquid crystal layer closest to each other are parallel to each other. When it is completely black. At this time, the black state is an important factor to improve the characteristics of the contrast ratio (contrast ratio).

In the process of orienting the liquid crystal, a liquid crystal cell having an angle in which the optical axis of the liquid crystal cell is perpendicular to or perpendicular to the optical axes of the first and second polarizing plates may be formed, and the first and second polarizing plates 70 (not shown) may be formed. In order to attach, only the vertical and horizontal lines are attached to the liquid crystal panel so that an optical axis alignment error of the liquid crystal cell with respect to the optical axes of the first and second polarizers 70 (not shown) may occur. have.

It is an object of the present invention to provide a polarizing plate attaching device capable of attaching first and second polarizing plates to be optimized with a cell axis in a liquid crystal panel so as to improve contrast ratio and a polarizing plate attaching method using the same.

The method of attaching a polarizing plate according to the present invention comprises: adsorbing a liquid crystal panel to an upper adsorption plate and adsorbing a first polarizing plate to a lower adsorption plate rotatable with a light control means at its center; Attaching the first polarizer to one outer surface of the liquid crystal panel; Positioning the liquid crystal panel to which the first polarizing plate is attached such that the first polarizing plate is in contact with the lower adsorption plate; Positioning a luminance meter through a second polarizer at a fixed position spaced apart from the liquid crystal panel to which the first polarizer is attached; Irradiating light onto the liquid crystal panel and the second polarizing plate to which the first polarizing plate is attached using the dimming means; The luminance of the light passing through the second polarizing plate through the luminance meter is rotated in the first angle range with respect to the origin and continuously measured to transmit the measured luminance and the angle of the lower suction plate to the computer. Steps; Rotating the lower adsorption plate at an angle of the lower adsorption plate corresponding to the maximum or minimum luminance value by a computer judgment; And attaching the second polarizing plate to the other outer surface of the liquid crystal panel positioned on the lower adsorption plate rotated at the specific angle.

The first optical axis of the first polarizing plate and the second optical axis of the second polarizing plate are characterized in that the disposed angle has a range of 90 ° ± 1 ° or 0 ° ± 1 °, the first angle range is ± 1 ° Is preferably.

The luminance meter is characterized in that it is provided inside the upper adsorption plate, the liquid crystal panel is located on the lower adsorption plate, the position is grasped by a vision camera, etc., it is preferable that the adsorption in the alignment state.

An apparatus for attaching a polarizing plate according to the present invention includes: a lower adsorption plate rotatable and having a light control means at a center thereof; An upper suction plate positioned to correspond to the lower suction plate; A luminance measuring device for measuring luminance of light emitted through the dimming means; The lower suction plate is connected to the luminance meter and the lower suction plate, and stores the measured luminance value and the rotation angle of the lower suction plate corresponding to the value, and the lower suction plate is the origin of the lower suction plate at the rotation angle of the lower suction plate corresponding to the maximum or minimum luminance value. It includes a computer instructing to have a state rotated relative to.

The luminance meter may be configured inside the upper suction plate, and the upper and lower suction plates may include a plurality of vacuum holes on their surfaces.

Since the first and second polarizing plates are attached to each liquid crystal panel to be optimized for each liquid crystal panel, there is an effect of providing a liquid crystal display device having a high display quality with improved contrast ratio by maximizing black brightness.

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

5 is a schematic exploded perspective view of a liquid crystal display according to an exemplary embodiment of the present invention.

As illustrated, the liquid crystal display device 101 according to an exemplary embodiment of the present invention includes a liquid crystal panel 110 having a first and second polarizing plates 116 and 118 on its outer surface, a backlight unit 120, and a support. It is composed of the main 130, the cover bottom 140 and the top cover 150.

First, the liquid crystal panel 110 plays a key role in image display, and the lower substrate 114 which is an array substrate bonded to each other with a liquid crystal layer interposed therebetween and the upper substrate which is a color filter substrate. A first and second polarizing plates 116 and 118 having optical axes that cross each other substantially perpendicularly or substantially parallel to each of the upper substrate 112 and the lower substrate 114 and the outer substrate. It includes more. In this case, the first and second polarizing plates 116 and 118 do not have a state in which their optical axes are exactly perpendicular or parallel to each other, but maximize the black luminance in consideration of the state of the optical axis of the liquid crystal layer, that is, the cell axis. The first optical axis 117 of the first polarizing plate 116 and the second optical axis 119 of the second polarizing plate 118 form an angle of 90 ° ± 1 ° or 0 ° ± 1 °.

 Although not shown in the drawing, the lower substrate 114 is formed by crossing a plurality of gate lines and data lines to define a plurality of pixel regions, and each of the plurality of pixel regions is formed at each intersection point of the gate and data lines. A thin film transistor (TFT) including a gate electrode, a gate insulating film, a semiconductor layer, and a source and drain electrode spaced apart from each other is formed, and in each pixel area, a pixel electrode is connected to the drain electrode of the thin film transistor. Formed. In addition, the non-display area is connected to the plurality of gates and data wires outside the display area in which the plurality of pixel areas are formed, and includes a gate and a data pad.

Although not shown in the drawing, the upper substrate 112 corresponds to each pixel region, and color filter patterns of red, green, and blue colors are sequentially formed, and correspond to each pixel region. A black matrix covering each of the color filter patterns and covering the non-display elements such as the gate line, the data line, and the thin film transistor is provided. The common electrode is formed to cover the color filter pattern and the black matrix. It is.

In addition, at least one edge of the liquid crystal panel 110 may more accurately correspond to a gate and data pad portion on which the gate and data pad are formed, and connect a connection member such as a flexible printed circuit film (FPC) or a chip on film (COF). The printed circuit boards 134a and 134b are connected to each other, and the printed circuit boards 134a and 134b are tightly fixed to the side of the support main 130 or to the back of the cover bottom 140 during the modularization process. It is becoming.

In addition, the liquid crystal panel 110 having such a structure has a signal of a data driving circuit when a thin film transistor selected for each gate wiring is turned on by an on / off signal of a gate driving circuit which is scanned and transferred. Voltage is transmitted to the corresponding pixel electrode through the data line, and the arrangement direction of the liquid crystal molecules is changed by the electric field between the pixel electrode and the common electrode, thereby indicating a difference in transmittance.

In addition, the liquid crystal display device 101 according to the present invention is provided with a backlight unit 120 for supplying light to the rear surface of the liquid crystal panel 110 so that the difference in transmittance is expressed to the outside.

The backlight unit 120 includes a lamp 124 arranged along at least one edge length direction of the support main 130, a reflection plate 122 mounted on the cover bottom 140, and the reflection plate ( 122 includes a light guide plate 126 seated on and a plurality of optical sheets 128 interposed thereon.

In addition, a lamp guide 133 for guiding the lamp 124 is further provided, the lamp guide 133 has an opening toward the light guide plate 126 and is configured to surround the lamp 124, In addition to the protection of the lamp 124, the light is concentrated in the direction of the support main 130.

The liquid crystal panel 110 and the backlight unit 120 are modularized by being fastened to the top cover 150, the support main 130, and the cover bottom 140, and the top cover 150 of the liquid crystal panel 110 is formed. The cross-sectional shape of the cross-sectional shape is bent in a "b" shape to cover the upper surface of the non-display area and the outer surface of the support main 130, and the entire display area of the liquid crystal panel 110 is opened. Is done.

In addition, the support main 130 having a rectangular frame shape seated on the cover bottom 140 having such a structure and covering the edges of the liquid crystal panel 110 and the backlight unit 120 is the top cover 150 and the cover bottom. It is fastened to 140 and is modularized into one finished product.

Meanwhile, the first and second polarizing plates, which are the most characteristic configurations in the present invention, will be described in more detail.

The first and second polarizing plates 116 and 118 form a polarization axis by forming an iodine layer on the base film and stretching the film in one direction with tension. The first and second polarizers 116 and 118 may have their respective optical axes intersecting at an angle ranging from 90 ° ± 1 °, or at an angle ranging from 0 ° ± 1 °, depending on the driving mode of the liquid crystal display 101. Respectively formed on the outer surfaces of the upper substrate 112 and the lower substrate 114 of the liquid crystal panel 110 so as to divide incident light into polarization components, passing only light in a predetermined direction and absorbing other components or To be distributed. Here, the light is an electromagnetic wave and its vibration direction is perpendicular to the traveling direction, and the polarization is light that is biased to the vibration direction, and the light vibrates strongly in a specific direction among the directions perpendicular to the traveling direction. Therefore, the light emitted from the backlight unit 120 provided below the liquid crystal panel 110 has the same probability of vibration in all directions, and the first and second polarizers 116 and 118 are configured to display the backlight. Of the light emitted from the unit 120, only the light vibrating in the same direction as the optical axis is transmitted, and the light vibrating in the other directions plays a role in making light vibrating in a specific direction by absorbing or reflecting using a predetermined medium. .

The driving of the liquid crystal display device 101 including the liquid crystal panel 110 having the first and second polarizing plates 116 and 118 on the outer surface thereof utilizes optical anisotropy and polarization properties of liquid crystals (not shown). Done. That is, since the liquid crystal molecules in the liquid crystal layer (not shown) are thin and long in structure, the liquid crystal molecules have directionality and polarization in the arrangement of the liquid crystal molecules (not shown), and artificially apply an electric field to adjust the arrangement direction of the liquid crystal molecules. Can be. Therefore, if the orientation direction is arbitrarily adjusted, the image can be displayed by transmitting or blocking light in accordance with the alignment direction of the liquid crystal molecules by the optical anisotropy of the liquid crystal.

The first and second optical axes 117 and 119 of the first and second polarizers 116 and 118 are disposed in the 90 ° ± 1 ° range or 0 ° ± 1 with respect to the alignment error of the liquid crystal molecules. Since the first and second polarizing plates 116 and 118 are attached to the outer side surfaces of the upper substrate 112 and the lower substrate 114 to have an angle in a range of °, the optical axis of the liquid crystal molecules The intensity of the transmitted light is adjusted according to the degree of rotation, so that black and white and gray between the two colors can be expressed.

On the other hand, the liquid crystal display device 101 displays an image by transmitting or blocking light, but the contrast ratio should be improved in order to express a high-quality image, and the contrast ratio shows how clearly the image is seen on the screen. It can be expressed as the difference between the luminance of black and white on the scale indicating the, and is defined as the ratio of the luminance value of the white state to the luminance value of the black state at the center of the image display area.

Typically, the black and white ratios are factors that determine the brightness of the screen. When the liquid crystal display 101 is a TN mode using a twisted nematic liquid crystal and operates in a normally white mode, in particular, the black luminance state is a liquid crystal panel ( When the electric field is applied to the 110, the first and second optical axes 117 and 119 of the first and second polarizers 116 and 118 and the long axis of the liquid crystal molecules, that is, the cell axis are orthogonal to each other, and in this case, are fully black luminance states. The black luminance state is an important factor for improving the contrast ratio characteristic.

On the other hand, when operating in the normally black mode, the black luminance state is the first and second optical axes 117 and 119 of the first and second polarizing plates 116 and 118 when no electric field is applied to the liquid crystal panel 110. And the cell axes of the liquid crystal molecules in the liquid crystal layer closest to each other are parallel to each other. In this state, when the first and second optical axes 117 and 119 are perpendicular to each other, a perfect black luminance state is obtained. However, in the normally white mode, even if an electric field is applied, the cell axis is not perfectly perpendicular to the first and second optical axes 117 and 119. When the electric field is not applied in the normally black mode, the first axis may be caused by an orientation error. The optical axis of the optical axis 117 and the liquid crystal molecules adjacent thereto are not perfectly parallel to each other, and at the same time, the optical axes of the second optical axis 119 and the liquid crystal molecules adjacent thereto are not perfectly parallel to each other. Conditions for achieving the luminance state will be different.

In the present invention, the first polarizing plate 116 and the second polarizing plate (116) so as to have the lowest black luminance value in a state perpendicular to or horizontal to the liquid crystal panel 110 reflecting a cell axis that varies due to an alignment error, etc. The first and second optical axes 117 and 119 of 118 are attached to the outer surface of the liquid crystal panel 110 so as to form an angle in the range of 90 ° ± 1 ° or 0 ° ± 1 °.

Hereinafter, a method of attaching a polarizing plate to reflect the state of the liquid crystal panel according to the present invention to improve the black luminance will be described.

6A to 6D are cross-sectional views for attaching a polarizing plate to a liquid crystal panel according to an exemplary embodiment of the present invention. At this time, since the reference numerals given to the components of the liquid crystal display device are used as they are, the first polarizing plate attached to the outer side of the upper substrate and the second polarizing plate attached to the outer side of the lower substrate are used.

First, as shown in FIG. 6A, when the liquid crystal panel 110 is positioned on the lower adsorption plate 170 of the polarizing plate attaching device according to the present invention, the vision camera 160 located on the upper side of the liquid crystal panel 110 operates. After determining the position of), the liquid crystal panel 110 is aligned on the lower adsorption plate 170.

Next, as illustrated in FIG. 6B, the upper adsorption plate 180 is adsorbed on the aligned liquid crystal panel 110 so that the liquid crystal panel 110 is adsorbed onto the upper adsorption plate 180. In this case, the second polarizing plate 118 is positioned as the lower adsorption plate 170.

A plurality of vacuum holes (not shown) are formed in the upper adsorption plate 180 and the lower adsorption plate 170, and the vacuum holes (not shown) are connected to a vacuum device so that the liquid crystal panel 110 and the first adsorption plate have a vacuum suction force. The second polarizing plate 118 is fixed to a specific working position of the upper and lower suction plates 180 and 170. At this time, the lower adsorption plate 170 is inclined with respect to the surface of the liquid crystal panel 110 adsorbed on the upper adsorption plate 180 so that the second polarizing plate 118 and the liquid crystal panel 110 can be attached smoothly. It is fixedly positioned adjacent to the attachment roller 183 in the form. In addition, the upper suction plate 180 is installed perpendicular to the direction of gravity and is positioned to move forward while passing through the upper portion of the roller (183).

Next, one surface of the second polarizing plate 118 adsorbed to the lower adsorption plate 170 is inserted into the roller 183 while the liquid crystal panel 110 adsorbed to the upper adsorption plate 180 and its ends are in contact with each other. Subsequently, when the roller 183 is rotated, the second polarizing plate is interposed between the roller 183 and the upper suction plate 180 by friction in direct contact between the roller 183 and the second polarizing plate 118. 118 and the liquid crystal panel 110 are dragged in, so that front adhesion is sequentially performed. In this case, the liquid crystal panel 110 is moved together by moving the upper adsorption plate 180 itself, the second polarizing plate 118 is controlled by the vacuum pressure of the vacuum hole (not shown) the lower adsorption plate 170 As it slides off the surface, it moves toward the roller 183.

On the other hand, as a modification, the second polarizing plate is attached to the outer side of the upper substrate of the liquid crystal panel without the adsorption on the upper adsorption plate while the liquid crystal panel is positioned on the lower adsorption plate and aligned, and by using a robot arm or the like. The upper and lower surfaces of the liquid crystal panel may be changed, that is, the second polarizing plate may be in contact with the lower adsorption plate.

Next, as shown in FIG. 6C, the lower adsorption plate 170 positioned to be inclined so as to attach the second polarizing plate 118 to one outer surface of the liquid crystal panel 110 is again the upper adsorption plate (not shown). The liquid crystal panel 110 is positioned on the lower adsorption plate 170 by being adsorbed by the upper adsorption plate (not shown) and completed with the attachment of the second polarizing plate 118.

At this time, the polarizing plate attachment apparatus for attaching the polarizing plate according to the present invention is provided with a dimming means 173 for irradiating light to the center portion of the lower adsorption plate 170, and corresponds to the dimming means 173 And a luminance measuring device 185 capable of measuring luminance thereon. The luminance meter 185 may have a function of being positioned at a fixed position by itself when the luminance is measured, or may be provided at the center of the upper adsorption plate 180 as the dimming means 173.

In this case, the luminance meter 185 stores the measured luminance value and compares and determines the luminance value to derive the largest or smallest luminance value, and the lower suction plate 170 corresponding to the largest or smallest luminance value. In other words, the rotational state of the lower adsorption plate 170 may be stored so as to store the rotated angle with respect to the aligned origin and to implement the rotated state when the first polarizing plate 116 is attached. It is connected to the computer 187.

Therefore, according to this configuration, before the first polarizing plate 116 is attached, the first polarizing plate 116 is fixed to correspond to the liquid crystal panel 110 to which the second polarizing plate 118 located on the lower suction plate 170 is attached. After positioning at a distance, the dimming means 173 is turned on to irradiate light, and at the same time, the lower adsorption plate 170 is rotated clockwise and anticlockwise within a range of ± 1 ° from the currently aligned home position. Slowly rotate clockwise. In this case, the luminance meter 185 continuously measures luminance and stores the same in the computer 187 and simultaneously rotates the angle of the lower suction plate 170 corresponding to the measured luminance value with respect to the origin of the lower suction plate 170. Save it.

Thereafter, when the liquid crystal panel operates in the normally black mode, the computer 187 measures the rotated angle of the lower adsorption plate 170 when the liquid crystal panel has the smallest luminance value among the luminance values measured by self calculation. It is instructed to reflect and reflect this in the operation of the lower suction plate 170, so after completing the luminance measurement, the lower suction plate 170 is rotated relative to the origin at an angle indicated by the computer 187 It will be fixed. At this time, the first polarizing plate 116 is adsorbed onto the upper suction plate (not shown). In the drawing, the luminance meter 185 has a configuration separated from the upper suction plate (not shown).

Next, as shown in FIG. 6D, the agent adsorbed to the upper adsorption plate 180 with respect to the liquid crystal panel 110 which is fixed to the lower adsorption plate 170 rotated at a specific angle indicated by the computer 187. 1 The polarizing plate 116 is inserted into the roller 183 in a state in which the liquid crystal panel 110 adsorbed on the lower adsorption plate 170 and the ends thereof are in contact with each other, and then the rotation of the roller 187 is performed. The first polarizing plate 116 and the liquid crystal panel 110 are dragged between the roller 183 and the lower adsorption plate 170 by friction in direct contact between the roller 183 and the first polarizing plate 116, and thus the front adhesive is sequentially bonded. As a result, the first polarizing plate 116 is attached to the liquid crystal panel 110.

In this case, referring to FIG. 7, the first polarizing plate 116 does not necessarily become perpendicular or horizontal to the optical axis of the second polarizing plate (not shown), and reflects an error range of the cell axis of the liquid crystal layer. It is in the range of ± 1 ° and is in a vertical or horizontal state, but this reflects the maximum or minimum black luminance state by measuring the change in the cell axis that differs for each liquid crystal panel. This results in improving the contrast ratio of the display device.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is only an example, and those skilled in the art can make various modifications through the above-described embodiment.

1 is an exploded perspective view of a general liquid crystal display device.

2A and 2B schematically illustrate alignment of a liquid crystal cell and a polarizing plate at the time of applying an electric field and before applying the electric field in the conventional LCD.

3A to 3C are cross-sectional views schematically illustrating a polarizing plate attaching step to a conventional liquid crystal panel.

4 is a plan view of a liquid crystal panel with a polarizing plate attached by a conventional polarizing plate attaching method.

5 is a simplified exploded perspective view of a liquid crystal display according to an embodiment of the present invention.

6A to 6D are cross-sectional views for attaching a polarizing plate to a liquid crystal panel according to an exemplary embodiment of the present invention.

7 is a plan view of a liquid crystal panel with a polarizing plate attached by the method for attaching a polarizing plate according to the present invention.

<Description of Symbols for Main Parts of Drawings>

110: liquid crystal panel 112: upper substrate

114: lower substrate 116: first polarizing plate

118: second polarizing plate 170: lower adsorption plate

173: dimming means 185: luminance measuring instrument

187: computer

Claims (8)

Adsorbing the liquid crystal panel to the upper adsorption plate and adsorbing the first polarizing plate to the lower adsorption plate rotatable with a light control means at its center; Attaching the first polarizer to one outer surface of the liquid crystal panel; Positioning the liquid crystal panel to which the first polarizing plate is attached such that the first polarizing plate is in contact with the lower adsorption plate; Positioning a luminance meter through a second polarizer at a fixed position spaced apart from the liquid crystal panel to which the first polarizer is attached; Irradiating light onto the liquid crystal panel and the second polarizing plate to which the first polarizing plate is attached using the dimming means; The luminance of the light passing through the second polarizing plate through the luminance meter is rotated in the first angle range with respect to the origin and continuously measured to transmit the measured luminance and the angle of the lower suction plate to the computer. Steps; Rotating the lower adsorption plate at an angle of the lower adsorption plate corresponding to the maximum or minimum luminance value by a computer judgment; Attaching the second polarizer to the other outer surface of the liquid crystal panel positioned on the lower adsorption plate rotated at the specific angle; Polarizing plate attachment method comprising a. The method of claim 1, The first optical axis of the first polarizing plate and the second optical axis of the second polarizing plate, the arrangement angle of the polarizing plate, characterized in that the range of 90 ° ± 1 ° or 0 ° ± 1 °. The method of claim 1, And the first angle range is ± 1 °. The method of claim 1, And the luminance meter is provided inside the upper suction plate. The method of claim 1, Wherein the liquid crystal panel is located on the lower adsorption plate after the position grasped by a vision camera, etc., characterized in that the adsorption in the alignment is made. A lower suction plate which is rotatable and has a light control means at its center; An upper suction plate positioned to correspond to the lower suction plate; A luminance measuring device for measuring luminance of light emitted through the dimming means; The lower suction plate is connected to the luminance meter and the lower suction plate, and stores the measured luminance value and the rotation angle of the lower suction plate corresponding to the value, and the lower suction plate is the origin of the lower suction plate at the rotation angle of the lower suction plate corresponding to the maximum or minimum luminance value. Computer that instructs to have rotated about Polarizing plate attachment device comprising a. The method of claim 1, The brightness measuring device is a polarizing plate attachment device, characterized in that configured in the upper adsorption plate. The method of claim 1, The upper and lower suction plate is a polarizing plate attachment device having a plurality of vacuum holes on the surface.

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