KR100764262B1 - Polarizer for liquid crystal display device - Google Patents

Abstract

This invention discloses the polarizing plate for liquid crystal display devices which prevents the fall of the polarization efficiency by the error of an extending process in manufacture, and increases the sharpness of a liquid crystal display device. According to the disclosed invention, a plurality of polarizing films respectively transmit and stack beams polarized in a predetermined direction among incident beams. The first support layer adheres to an upper surface of the best polarizing film among the plurality of polarizing films to support the plurality of polarizing films. The second support layer adheres to the lower surface of the lowermost polarizing film of the plurality of polarizing films to support the plurality of polarizing films.

Polarizer, liquid crystal

Description

Polarizing plate for liquid crystal display device {POLARIZER FOR LIQUID CRYSTAL DISPLAY DEVICE}

1 is a view showing the structure of a polarizing plate for a conventional liquid crystal display device.

2 is a view showing a cell cross section and structure of a conventional IPS mode LCD.

3 is a view showing a polarization phenomenon of a polarizing plate due to unevenness in the stretching direction.

4 is a diagram illustrating a structure of a polarizing plate for a liquid crystal display according to a first embodiment of the present invention.

5 is a diagram illustrating a structure of a polarizing plate for a liquid crystal display according to a second exemplary embodiment of the present invention.

6 is a view for explaining the technical principle of a PVA polarizing plate of a multi-layer structure according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

402: polarizing film 404: first support layer

406: second support layer 408: release film

410: pressure-sensitive adhesive layer 502: polarizing film

504: support layer 508: release film

510: pressure-sensitive adhesive layer

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing plate for a liquid crystal display device, and more particularly, a plurality of polarizing films are formed to change angles of each transmission axis by an error degree of an extending process, and a polarizing film is formed in consideration of errors of a plurality of stretching processes. It relates to a polarizing plate for liquid crystal display device.

1 is a view showing the structure of a conventional polarizing plate for a liquid crystal display device.

The polarization function imparts polarization characteristics by dyeing the polarizing film 102 with polyvinnyl alcohol (PVA) after stretching by iodine or dyes. The function of triacetyl cellulose (TAC) functions as a support for mechanically supporting the PVA 102 having a polarization function. PSA serves as a layer having an adhesive function to adhere the polarizing plate to the LCD panel. Such polarizers in LCDs generally adhere to array substrates and color filter substrates to perform polarization functions.

2 is a diagram showing a cell cross section and a structure of a general transverse electric field LCD.

After attaching the polarizing plate 202 under the array substrate 204, the backlight light is polarized by linearly polarized light. The analyzer 208 on the color filter substrate 206 has a transmission direction in which the polarized light in the array substrate 204 is rotated and a transmission axis of 90 ° is rotated. At this time, the liquid crystal 210 serves as a light valve to implement dark and white.

The polarization function in the prior art includes a step of performing a stretching process during the PVA layer process to mechanically align iodine or dyes in one direction. In the stretching process, the stretching direction should ideally align the iodine molecules or dyes in one direction, but in the actual stretching process, the abnormal alignment of iodine molecules or dyes may occur within a certain angle in the stretching direction.

The polarized light of the polarizing plate due to the error of the stretching process has a transmission axis within a range in which the polarization direction is constant as shown in FIG. 3. It is a figure which shows the polarization phenomenon of the polarizing plate by the nonuniformity of a extending direction.

Light transmitted in another direction within the stretching process error range except for light polarized in the same direction as the transmission direction of the PVA layer 102 in FIG. 3 becomes a factor of lowering polarization efficiency. The actual transmitted light within this stretching process error range is within a constant angular range of (-α to + α). The range will become smaller with increasing uniformity of the stretching process, but it is impossible to completely erase the mechanical stretching process.

Accordingly, the present invention has been made to solve the above problems of the prior art, the object of the present invention is to provide a polarizing plate to increase the clarity of the liquid crystal display device by preventing a decrease in polarization efficiency due to errors in the stretching process in the manufacturing have.

In order to achieve the above object, the present invention provides a plurality of polarizing films which are respectively transmitted and laminated through a beam polarized in a predetermined direction among the incident beams; A first support layer adhered to an upper surface of an uppermost polarizing film among the plurality of polarizing films to support the plurality of polarizing films; And a second support layer adhered to a lower surface of the lowermost polarizing film among the plurality of polarizing films to support the plurality of polarizing films.

In addition, the present invention includes a plurality of polarizing films for transmitting the polarized beams in the transmission direction within the error range of the stretching process centered on the polarization axis among the beams that are placed every other; And a plurality of support layers that are alternately disposed between the plurality of polarizing films to support the plurality of polarizing films, respectively.

(Example)

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

4 is a view showing the structure of a polarizing plate for a liquid crystal display according to a first embodiment of the present invention. The polarizing plate for a liquid crystal display according to the first exemplary embodiment of the present invention includes a plurality of polarizing films 402, a first supporting layer 404, a second supporting layer 406, and a release film 408.

The plurality of polarizing films 402 transmit and stack beams polarized in a predetermined direction among the incident beams. According to the first embodiment of the present invention, it is preferable that the plurality of polarizing films 402 have a slightly mismatched transmission axis. According to the first embodiment of the present invention, the plurality of polarizing films 402 are more preferably polyvinyl alcohol films.

The first support layer 404 is adhered to an upper surface of the best polarizing film of the plurality of polarizing films 402. The second support layer 406 is attached to the lower surface of the lowermost polarizing film of the plurality of polarizing films 402. The first and second support layers 404 and 406 support the plurality of polarizers 402. According to a first embodiment of the present invention, the first and second support layers 404 and 406 are preferably triacetyl cellulose layers, respectively.

The release film 408 is adhered to the lower surface of the second support layer 406 by a pressure sensitive adhesive (PSA) applied to the lower surface of the second support layer 406 to form the plurality of polarizing films ( 402 and the first and second support layers 404 and 406.

5 is a diagram illustrating a structure of a polarizing plate for a liquid crystal display according to a second exemplary embodiment of the present invention. The polarizing plate for a liquid crystal display according to the second exemplary embodiment of the present invention includes a plurality of polarizing films 502, a plurality of support layers 504, and a release film 508.

Each of the plurality of polarizing films 502 is positioned so as to transmit beams polarized in a predetermined direction among the incident beams. According to the exemplary embodiment of the present invention, it is preferable that the plurality of polarizing films 502 have transmission axes that are slightly mismatched. According to an embodiment of the present invention, the plurality of polarizing films 502 are more preferably polyvinyl alcohol films.

The plurality of support layers 504 are alternately disposed between the plurality of polarizing films 502 to respectively support the plurality of polarizing films 502. According to a second embodiment of the present invention, the plurality of support layers 504 are preferably triacetyl cellulose layers, respectively.

The release film 508 is adhered to the lower surface of the lowermost support layer through a pressure-sensitive adhesive layer 510 applied to the lower surface of the lowermost support layer among the plurality of support layers, so that the plurality of polarizing films 502 and the plurality of support layers 504 To protect.

6 is a view for explaining the technical principle of a PVA polarizing plate of a multi-layer structure according to an embodiment of the present invention.

As shown in FIG. 6, the light transmitted through the PVA layer 1 is transmitted with an angle of ± α in the transmission direction of the polarizer, assuming that the error range of the stretching process is α.

The PVA two layers are manufactured such that the transmission axis is rotated by an angle in the error range α of the stretching process in the transmission direction of the PVA one layer. Accordingly, the light passing through only two layers of PVA has a transmission range of an angle of 0 to 2α rotated by an angle of α relative to an angle of ± α which is a transmission range of light transmitted through the PVA 1 layer. However, since the light that has already passed through the PVA 1 layer passes through the PVA 2 layer again, the transmission range of the light transmitted through the PVA 1 layer and the PVA 2 layer has an angle of 0 to α.

In addition, the three PVA layers are manufactured such that the transmission axis is rotated by an angle of the error range (-α) of the stretching process in the transmission direction of the PVA one layer. Thus, the light passing through only three PVA layers has a transmission range of an angle of -2α to 0 rotated by an angle of α relative to an angle of ± α which is a transmission range of light transmitted through one PVA layer. However, light that has already passed through the PVA 1 layer and the PVA 2 layer passes through the PVA 3 layer again. Therefore, when the PVA 3 layer transmits light transmitted through the PVA 1 layer and the PVA 2 layer again, only the light corresponding to the polarization axis of the polarizing plate to be designed, that is, the light of 0 degrees, which is the transmission direction of the PVA 1 layer, is transmitted.

Although the above PVA formation layer is a case where three layers are formed, the same effect can be acquired at the time of forming two or more layers.

The formation of the multilayer PVA layer reduces the transmission axis of the polarizer due to the error of the stretching process, thereby increasing the polarization efficiency and realizing a clear screen of the liquid crystal display device.

The present invention has been described above as a specific preferred embodiment, but the present invention is not limited to the above-described embodiments, and the present invention is not limited to the above-mentioned claims without departing from the gist of the present invention. Anyone with a variety of variations will be possible.

As described above, according to the present invention, the polarization efficiency is increased by the nonuniformity correction of the stretching step in the polarizing plate manufacturing process, thereby improving the image quality sharpness of the liquid crystal display device.

Claims (7)

A plurality of polarizing films each having a beam polarized in a predetermined direction among the incident beams, and stacked; A first support layer adhered to an upper surface of an uppermost polarizing film among the plurality of polarizing films to support the plurality of polarizing films; And And a second support layer adhered to a lower surface of a lowermost polarizing film of the plurality of polarizing films to support the plurality of polarizing films. The polarizing plate for a liquid crystal display device of claim 1, wherein the plurality of polarizing films have a minute mismatched transmission axis. The polarizing plate for a liquid crystal display device of claim 1, wherein each of the plurality of polarizing films is a polyvinyl alcohol film. The polarizing plate of claim 1, wherein each of the first and second support layers is a triacetyl cellulose layer. The method of claim 1, further comprising a release film that is bonded to the lower surface of the second support layer via a pressure-sensitive adhesive layer applied to the lower surface of the second support layer to protect the plurality of polarizing films and the first and second support layers. The polarizing plate for liquid crystal display devices characterized by the above-mentioned. A plurality of polarizing films each of which transmits the beam polarized in the transmission direction within an error range of the stretching process centered on the polarization axis among the beams which are placed in every other; And And a plurality of support layers disposed alternately between the plurality of polarizing films to support the plurality of polarizing films. The method of claim 6, further comprising a release film that is bonded to the lower surface of the lowest support layer via a pressure-sensitive adhesive layer applied to the lower surface of the lowermost support layer of the plurality of support layers to protect the plurality of polarizing film and the plurality of support layers. The polarizing plate for liquid crystal display devices characterized by the above-mentioned.

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