JP2003098347A - Polarizing plate and method for inspecting the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing plate to which a not easily erasable identifying mark is imparted and a method for inspecting the same by focusing attention to a property of the polarizing plate. SOLUTION: To the polarizing plate 1 transmitting only a specified polarized light component with respect to incident light, a notation such as a character, a sign or a mark is imparted by partial deterioration of the polarization degree with heating and the notation is located on the outside of a display region 4 of a liquid crystal display panel P. Also the identifying mark is visually recognized by overlaying the two polarizing plates 1, 5 on each other so as to make axes of polarization 6, 7 perpendicularly intersect with each other and by making light from a light source pass through them.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarizing plate used for a liquid crystal display panel and the like and a method for inspecting the polarizing plate.

[0002]

2. Description of the Related Art In recent years, a liquid crystal display device has been actively commercialized and researched and developed as a basic device of a flat panel display. Liquid crystal display modes used in liquid crystal display devices include STN (super twisted nematic) mode, TN (twisted nematic) mode, and IPS (in-plane switching) mode. Since these liquid crystal display elements utilize the optical rotatory power and birefringence of light associated with the alignment state of liquid crystals, a polarizing plate is used. A polarizing plate is generally made by stretching a polyvinyl alcohol film and dyeing it with a dichroic dye such as iodine.
It has a structure in which its surface is laminated with a protective film such as triacetyl cellulose. This polarizing plate is an optical member having a polarization function of transmitting light oscillated in a certain direction and absorbing light oscillated in an orthogonal direction.

[0003]

With the active commercialization of liquid crystal display panels, various types of polarizing plates have been adopted. However, the polarizing plate is a semi-transparent film with the same appearance even if the specifications are slightly different. Therefore, for example, when the polarizing plate manufacturer delivers the polarizing plate, the type information is written on the polarizing plate packaging bag. However, it is difficult to distinguish from the appearance of the polarizing plate after taking out the polarizing plate from the packaging bag. Therefore, at the manufacturing site, which electronic element,
There has been a confusion about whether it is used for electronic devices, parts, etc., or where it is used for electronic elements, electronic devices, parts, etc. Further, after disassembling the liquid crystal display device, there is a problem that it is impossible to distinguish the direction of the polarizing plate and whether the polarizing plate is the back side or the front side.

To solve such a problem, it is possible to solve the above problem by marking the polarizing plate with an identification mark by printing or the like. However, it may be rubbed when being carried or scraped by coming into contact with other parts. However, there was a problem that printing deteriorated.

Therefore, an object of the present invention is to provide a polarizing plate provided with an identification mark which is not easily erased and an inspection method of the polarizing plate, paying attention to the property of the polarizing plate.

[0006]

In order to solve the above problems and achieve the above objects, a polarizing plate according to claim 1 of the present invention is a polarizing plate which transmits only a specific polarization component for incident light. Characteristically, characters, symbols, marks, or the like are written on the surface by partially degrading the degree of polarization by applying heat.

According to the present invention, by utilizing the property of the polarizing plate that is easily deformed by heat, notations such as characters, symbols or marks are applied by heating to form a heat-treated region in which the degree of polarization is partially deteriorated. Since it is provided, it is possible to display quality numbers, by displaying the serial number, or by displaying which electronic element, electronic device, component, etc. is used.
It can be used for process control.

A polarizing plate according to a second aspect of the present invention is used in a liquid crystal display panel in which a liquid crystal layer is sandwiched between a pair of substrates, and is a polarizing plate which transmits only a specific polarization component for incident light. Heat is applied to partially deteriorate the polarization degree,
Characters, symbols, marks, or the like are given, and the notation is located outside the display area of the liquid crystal display panel.

According to the present invention, like the polarizing plate according to the first aspect, it can be utilized for quality control, process control, etc. However, since the heat treatment area is located outside the display area of the liquid crystal display panel, The liquid crystal display panel can be used for the quality control, process control, etc. without degrading the display quality.

According to a third aspect of the present invention, there is provided a method for inspecting a polarizing plate, wherein the polarizing plate according to the first or second aspect is a polarizing plate for inspection, and the polarization axis of the polarizing plate for inspection and the polarization of the polarizing plate of the polarizing plate. It is characterized in that the transmitted light from the light source is observed by superimposing them so that their axes are orthogonal to each other, and that notations such as characters, symbols or marks are visually recognized from the deterioration of the polarization degree of the heat treatment region.

According to the present invention, when the transmitted light from the light source is observed by arranging the polarization axes of the inspection polarizing plate and the polarizing axis of the polarizing plate at right angles to each other, the region not subjected to the heat treatment is Although the transmitted light is blocked and looks dark, the heat treatment area looks bright because the transmitted light is not blocked because the polarization degree is deteriorated.If the heat treatment is performed with letters, symbols or marks, the letters, symbols Alternatively, the notation such as a mark can be visually recognized.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

The present embodiment is a polarizing plate 1 used on the front and back surfaces of a liquid crystal display panel P, as shown in FIGS. The liquid crystal display device having such a structure is called a two-sheet polarizing plate system, but there is also a one-sheet polarizing plate system. As shown in FIG. 3, the liquid crystal layer C is sandwiched between the pair of substrates L1 and L2, and the polarizing plate 1 is attached to the outside of each of the pair of substrates L1 and L2. In the case of a reflection type liquid crystal display device, a reflection film is attached to one polarizing plate 1. In addition, in the STN method, a retardation plate is usually attached in addition to the polarizing plate 1. Reference numeral BL is a backlight, S is a sealing material, and IC is a driving IC. The polarizing plate 1 that transmits only a specific polarization component for incident light is
An optical member that visualizes changes in the orientation of liquid crystals.

As shown in FIG. 2, the heat treatment area 3 of the polarizing plate 1 partially deteriorates the degree of polarization due to the heat of the laser beam machine 2 and is marked with characters, symbols or marks. There is. These notations are used as identification marks. The position of the heat treatment area 3 is located outside the display area 4 of the liquid crystal display panel P. The heat treatment region 3 is formed by utilizing the property of the polarizing plate 1 that is easily deformed by heat. Any heating method other than laser processing, such as hot pressing, may be used as long as it is by heat.

A method of inspecting the polarizing plate 1 having the heat-treated region 3 as described above will be described below. The polarization axis 6 of the inspection polarization plate 5 and the polarization axis 7 of the polarization plate 1 are arranged so as to be orthogonal to each other, and the transmitted light from the light source 8 is observed. In the region where the heat treatment is not performed, the transmitted light is blocked by the polarized light and appears dark, but in the heat treated region 3, the incident light of the polarization component which is not parallel to the polarization axis 7 is transmitted because the polarization degree is deteriorated. Looks bright. Therefore, the notation such as characters, symbols or marks can be visually recognized from the deterioration of the polarization degree of the heat treatment region 3. In addition, the heat treatment area 3 has a liquid crystal display panel P.
The display quality of the liquid crystal display panel P is not degraded because it is located outside the display area 4. In addition, although the inspection polarizing plate 5 is superposed on the polarizing plate 1 in FIG. 2, even when the inspection polarizing plate 5 is superposed below the polarizing plate 1, the notation such as characters, symbols or marks is visually recognized. can do. The inspection polarizing plate 5 is used for the inspection of the polarizing plate 1 and is the same as the polarizing plate 1.

Therefore, in the case of disassembling the two-polarizing plate type liquid crystal display device, it may not be conventionally known whether the polarizing plate 1 is on the upper side or the lower side. Then, since heat is applied to the polarizing plate 1 to partially deteriorate the degree of polarization and characters, symbols, marks, or the like are written, such confusion can be prevented. Further, since the two polarizing plates 1 can be used to inspect each other for inscriptions such as letters, symbols or marks by the above-described inspection method, it is not necessary to separately prepare the inspection polarizing plate 5. Furthermore, since it is possible to inspect notations such as letters, symbols or marks for the first time using two polarizing plates 1, use as hidden letters or symbols not to be noticed by others (other companies). Is also possible.

On the other hand, even in the case of the one-sheet polarizing plate system,
The front and back of the polarizing plate 1 may be mistaken, but due to the notation such as letters, symbols, marks, etc., this notation can be visually recognized correctly, whether it is reversed left or right, etc.
Such mistakes can be prevented. In addition, in the present embodiment, since the polarizing plate 1 is heated to write characters, symbols, marks, or the like, the printing may be deteriorated by being rubbed when being carried or being scraped by coming into contact with other parts. Absent.

As described above, in this embodiment, the liquid crystal display panel P is used.
The polarizing plate 1 to be stuck on the polarizing plate 1 of the present invention has been described above.
It goes without saying that the inspection method is not limited to that used for the liquid crystal display panel P or the liquid crystal display device.

[0019]

EFFECTS OF THE INVENTION According to the polarizing plate of the present invention, by utilizing the property of being easily deformed by heat, characters, symbols, marks or the like are given by heating to deteriorate the polarization degree of the heated portion, Can be used as an identification mark, quality control,
It is possible to use it for process control.

Further, according to the polarizing plate inspection method of the present invention, the notation such as characters, symbols or marks can be visually recognized by stacking two polarizing plates.

[0021]

[Brief description of drawings]

FIG. 1 is a perspective view illustrating a heat treatment method for a polarizing plate of the present invention.

FIG. 2 is a perspective view illustrating a method for inspecting a polarizing plate according to the present invention.

FIG. 3 is a cross-sectional view showing a configuration example of a liquid crystal display device.

[Explanation of symbols]

1 Polarizer 2 Laser processing machine 3 Heat treatment area 4 display area 5 Polarizing plate for inspection 6 Polarizing axis of inspection polarizing plate 7 Polarizing axis of polarizing plate 8 light sources L1, L2 a pair of substrates S seal material C liquid crystal layer BL backlight P liquid crystal display panel IC driving IC

Claims (3)

[Claims] 1. A polarizing plate that transmits only a specific polarized component with respect to incident light, and is subjected to heat to partially deteriorate the degree of polarization, and is marked with characters, symbols or marks. Polarizing plate characterized by. 2. A polarizing plate which is used for a liquid crystal display panel in which a liquid crystal layer is sandwiched between a pair of substrates, and which transmits only a specific polarization component with respect to incident light, and heat is applied to partially polarize the polarization degree. A polarizing plate characterized by degrading and denoting characters, symbols, marks, or the like, and the denotation being located outside the display area of the liquid crystal display panel. 3. The polarizing plate according to claim 1 or 2,
The polarizing plates for inspection are overlapped and aligned so that the polarizing axis of the polarizing plate for inspection and the polarizing axis of the polarizing plate are orthogonal to each other, and the transmitted light from the light source is observed, and the degree of polarization of the heat treatment region is deteriorated. A method for inspecting a polarizing plate, which is characterized by visually recognizing characters, symbols or marks.