KR20010001776A - Sheet assembly of a back light unit for liquid crystal display device - Google Patents

Abstract

PURPOSE: A sheet assembly of a backlight unit for an LCD(liquid crystal display) is provided to maintain tolerance of prism patterns regular against defect factors such as impurity and pitch error while keeping the mountain area of each prism pattern straight. CONSTITUTION: In a backlight unit(100) for an LCD, light of a lamp(11) is projected directly into a light panel(30) or reflected by a lamp cover(20) to be projected into a one side of the light panel(30). A prism sheet(50) delivers the light to a protective sheet(60). Herein, the prism sheet(50) has plural prism patterns individually divided at regular intervals and continuously arranged with different heights while keeping a mountain straight. Thus, the prism sheet(50) maintains strong tolerance against defect factors such as impurity and pitch error. After that, the protective sheet(60) delivers the light to an image panel(2) to display the desired image on an LCD panel(2).

Description

Sheet assembly of a back light unit for a liquid crystal display device

The present invention relates to, for example, a sheet assembly employed in a backlight unit for a liquid crystal display device, and more particularly, to improve the shape of the prism patterns, to maintain the acid region of each prism pattern in a straight line, The present invention relates to a sheet assembly of a backlight unit for a liquid crystal display device in which two objectives, such as "obtaining uniform visibility" and "normal light efficiency", can be achieved at a time by maintaining the resistance of prism patterns normally.

Recently, as the modern society becomes information socialized, the importance of the liquid crystal display, which is one of the information display devices, is gradually increasing.

In such a liquid crystal display device, in particular, the role and function of the backlight unit is becoming an important task. This is because the size and light efficiency of the liquid crystal display device vary depending on the structure of the backlight unit, so that the overall mechanical and optical characteristics of the liquid crystal display device are many. Because it is affected.

The structure of a conventional backlight for a liquid crystal display device is, for example, US Patent No. 5567042 "Reflector for flat panel display backlight unit", US Patent No. 5592193 "Backlit array for LCD display panel" (Backlighting arrangement for LCD display panel), US Patent No. 5608553 "Back light for liquid crystal display", US Patent No. 5640483 "Backlighting system using total internal reflection utilizing total internal reflection ".

In such a conventional backlight unit for a liquid crystal display device, a plurality of sheet assemblies are generally interposed between the front surface of the light guide plate and the image panel. The sheet assembly is, for example, a combination of a diffusion sheet, a prism sheet, and a protective sheet. Is done. In this case, an image panel made of a glass material is disposed on the outermost surface of the sheet assembly to serve to display image information desired by the user to the outside.

In general, the light rays output from the light guide plate maintain the output angle twisted about 60 ° to 80 ° with respect to the normal direction of the exit surface.

At this time, the prism sheet disposed above the light guide plate spectroscopy the light beams output from the light guide plate, and induces the output light to have an output angle in the same direction as the normal line of the emission surface. In order to convert the output angle of the output light, a plurality of prism patterns having, for example, a "triangular prism shape formed with hills and valleys" are generally disposed on the surface of the prism sheet, and these prism patterns are continuously arranged in a row on the surface of the prism sheet. To form an ordered structure. In this case, the acid regions of the prism patterns form a straight line extending straight so that the "change of the output angle of the output light" can be made smoothly.

The shape of such conventional prism patterns is described, for example, in US Pat. No. 55,574,33 "Transmissive liquid crystal display having prism lens film for light illumination and wave lens film. for light diffusion ”, US Pat. No. 5381309, " Backlit display with enhanced viewing properties. "

In the production line, when the prism sheet is disposed on the light guide plate, the light gain of about 1.5 times can be obtained. However, as described above, since the prism patterns of the prism sheet have a straight shape in which the acid regions are straight, Each prism pattern causes a problem that is very sensitive to defective factors such as "foreign material" and "pitch error".

For example, when foreign matter such as particles flows into a predetermined region of the prism sheet during the assembling process of the backlight unit, the prism sheet exhibits a "change in output angle of output light" different from other regions in the region into which the foreign matter has flowed in. , "Problems that the visibility is exceptionally lowered only in the inflow portion of foreign matter", and eventually, the visibility of the final finished backlight unit causes a problem that is greatly uneven.

Recently, in order to solve this problem, the mountain region of the prism patterns is changed to a chaos shape of a curved line rather than a straight line, and through this, each prism pattern has a width and width in which the prism patterns are fixed in the left and right directions. A method of forming a profile having a change in the height and width of a certain width in the up and down directions has been devised. In this case, the prism sheets have a property of slightly deteriorating visibility over the entire surface thereof, so that even if foreign matters are introduced into their specific area, only the portion of the foreign matters is inferior in visibility. As a result, the prism sheet may have some resistance to defect factors such as "foreign material" and "pitch error".

However, there are some serious problems in operating such a conventional backlight unit for a liquid crystal display.

As described above, in recent years, in the production line, in order to allow each prism pattern to have a certain degree of resistance to defect factors such as "foreign material" and "pitch error", the chaos of a curved line rather than a straight line is formed in the acid region of the prism patterns. The method of changing to a shape is taken.

In this case, however, "visibility uniformity" of the finally completed backlight unit can be obtained, but since each prism pattern has a structure in which its acid region is changed to a curved chaotic shape, each prism pattern has its own longitudinal direction. In addition to the light rays that are incident vertically with respect to the light beams, the light rays that are incident horizontally are also refracted to emit light, thereby causing another problem that the overall light efficiency is greatly reduced.

In addition, when the prism sheet has a laminated structure of two sheets, the above-described light efficiency decrease becomes more serious, and the overall light efficiency decrease range reaches 8% to 10%.

In order to prevent such a decrease in light efficiency, it is best to keep the acid regions of each prism pattern in a straight line, but in this case, as described above, since the uniformity of visibility of the finally completed backlight unit is greatly reduced, the conventional production line The situation is not prepared.

Accordingly, an object of the present invention is to maintain the resistance of the prism patterns to defect factors such as "foreign material" and "pitch error" while maintaining the acid regions of the respective prism patterns in a straight line.

Another object of the present invention is to prevent the degradation of the light efficiency of the backlight unit by keeping the acid regions of the respective prism patterns in a straight line.

Still other objects of the present invention will become more apparent from the following detailed description and the accompanying drawings.

1 is an exemplary view showing a backlight unit for a liquid crystal display device employing the present invention.

Figure 2 is an enlarged view illustrating a sheet assembly according to an embodiment of the present invention.

Figure 3 is an exemplary view showing the arrangement of the prism patterns formed on the prism sheet of the present invention from the top.

Figure 4 is an enlarged view illustrating a sheet assembly according to another embodiment of the present invention.

In order to achieve the above object, in the present invention, while maintaining the mountains of the prism patterns formed on the surface of the prism sheet in a straight shape, the individual partitions are separated from each other, and the heights of the divided prism patterns are diversified. Each of the prism patterns is vertically aligned so that the acid formed on each of the prism patterns is slightly twisted left and right. In this case, each of the prism patterns can form a "profile with a predetermined width twisted in the left and right directions and a profile having a constant height and width change in the up and down directions", so that each prism sheet is formed on its entire surface. As a result, the visibility is slightly decreased, so that even if foreign matters are introduced into a specific part thereof, the problem is that "only the portion where the foreign material has been introduced is not unusually low in visibility." The prism sheet can have a certain degree of resistance to defect factors such as "foreign material" and "pitch error".

At this time, as described above, since the prism patterns of the present invention maintain the mountain region in a straight shape, only the light incident perpendicularly to the longitudinal direction of the prism is refracted, and the light is incident. Since no refraction is performed, the prism sheet of the present invention can maintain a normal level of light efficiency.

Hereinafter, a sheet assembly for a backlight unit of a liquid crystal display according to the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 1, in the backlight unit 100 for a liquid crystal display device employing the present invention, one side of the light guide plate 30 is provided with a lamp 10 used as a light source of the liquid crystal display device. 10 is wrapped by the lamp cover 20. At this time, the lamp 10 is connected to the connector (not shown) by a wire, and the connector supplies the lamp 10 with electric energy of an appropriate voltage, thereby inducing the lamp 10 to emit light at a constant brightness. Play a role.

Here, the light guide plate 30 disposed on the side of the lamp cover 20 serves to convert the light of the line light source output from the lamp 10 into the light of the surface light source.

In this case, a plurality of reflective dots (not shown) are formed on the rear surface of the light guide plate 30 to diffuse the light incident from the lamp 10. These reflecting dots keep their size small in the area adjacent to the lamp 10 to induce a small amount of light spreading, and maintain the size of the reflecting dot large in an area away from the lamp 10, thereby increasing the overall amount of light spreading. Induce as much as possible. In this case, the light guide plate 30 may maintain a uniform amount of light spread over its entire surface. As a result, the light beam output to the image panel via the light guide plate 30 may have uniform luminance across the entire surface of the light guide plate 30. Can be represented.

Here, a rear reflector (not shown) reflecting the light of the lamp 10 to the front of the light guide plate 30 is formed on the rear surface of the light guide plate 30 to be spaced apart from the light guide plate 30 by a predetermined distance. In the sheet assembly 70 is laminated.

Looking at the structure of the sheet assembly 70 in more detail, first, the diffusion sheet 40 for uniformly diffusing the light incident from the lamp 10 is formed on the surface closest to the light guide plate 30. In addition, a prism sheet 50 is formed on the entire surface of the diffusion sheet 40 to speculate light rays output through the diffusion sheet 40 so that the output light has an output angle in the same direction as the normal line of the emission surface. do. In general, since the prism sheet 50 is sensitive to scratches, a protective sheet 60 having a protective function is attached to the front surface of the prism sheet 52 to protect the prism sheet 50.

At this time, the image panel 2 for displaying information is placed on the front surface of the protective film 50 to perform a good image information display function, each of the above components is stably stored in the storage space of the mold frame (1).

In the backlight unit 100 of the present invention having the above-described structure, as shown in FIG. 2, the base surface of the prism sheet 50 has, for example, a "triangular prism shape in which the peak 53 and the valley 52 are formed." A plurality of prism patterns 51 are disposed.

At this time, as shown in the figure, each prism pattern 51 is formed in the shape of a straight line 53, and separately divided so as to be spaced apart a certain distance, while maintaining the angle θ of, for example, 90 ° In the state of maintaining the different height, it forms a structure continuously arranged laterally of the base surface. Here, each prism pattern 51 is arranged in the longitudinal direction such that the peak 53 is slightly twisted to the left and right.

For example, as shown in FIG. 3, the peaks 53a of the prism patterns 51a and the peaks 53b of the prism patterns 51b adjacent to each other are arranged to the left and right by the separation distance P. FIG.

The structure of the prism patterns 51 forms the gist of the present invention. Of course, the conventional prism patterns 51 have a completely different structure.

In the conventional case, the prism patterns were formed in a chaotic shape instead of a straight line in order to have a certain degree of resistance to defect factors such as "foreign material" and "pitch error". However, in this case, each prism pattern causes not only light incident vertically with respect to its longitudinal direction but also light incident horizontally, thereby causing another problem that the overall light efficiency is greatly reduced. It was.

Of course, if the acid region of each prism pattern is kept straight, this problem can be prevented in advance, but in this case, since the uniformity of visibility of the finally completed backlight unit is greatly reduced, a conventional production line does not provide any countermeasures. I wasn't.

In the present invention, in consideration of such a problem in advance, as described above, in the state in which the peaks 53 of the prism patterns 51 formed on the surface of the prism sheet 50 are kept in a linear shape, they are separately divided so as to be spaced apart from each other. In addition, the heights of the divided prism patterns 51 are diversified, and the prism patterns 51 are vertically oriented so that the peaks 53 formed on the prism patterns 51 are slightly twisted left and right. Align it.

When the present invention is practiced, each of the prism patterns 51 forms a “profile having a predetermined width twisted in the left and right directions and a profile having a predetermined height and width change in the up and down directions”, so as to form a peak 53. ) Can obtain the same effect as forming the "curved chaotic shape", as a result, each prism sheet 50 has a characteristic that the visibility is slightly reduced over its entire surface, thereby Even if a foreign material is introduced into a specific portion of the "only foreign matter introduced portion is not unusually low visibility problem" does not occur, after all, the prism sheet 50 of the present invention "foreign material", "pitch error", etc. It can have a certain degree of resistance to the defective factor of.

Of course, as described above, since the prism patterns 51 of the present invention hold the peak 53 in a straight line, only the light incident perpendicularly to the longitudinal direction of the prism pattern 51 is refracted and then emitted horizontally. The refractive rays do not perform much refraction with respect to the incident light beam, and as a result, the prism sheet 50 of the present invention can maintain a normal level of light efficiency.

In short, when the present invention is achieved, the prism patterns 51 for the defective factors such as "foreign material" and "pitch error" while maintaining the straight line 53 of each prism pattern 51 in the production line. Since the resistance can be maintained normally, the two objectives of securing uniform visibility and securing normal light efficiency can be achieved at once.

On the other hand, as shown in Figure 4, according to another embodiment of the present invention, the prism sheet 50 may have a structure in which two or more sheets are continuously stacked instead of a single layer. As an example, the case where two prism sheets 50 are laminated is shown. In this case, the prism patterns 51 formed in each layer of the prism sheet 50 have an arrangement structure perpendicular to each other for each layer.

As described above, even when the prism sheet 50 has a multi-layer structure, the prism patterns 51 formed on the prism sheets 50 of each layer maintain the acid 53 in a straight line like the above-described embodiment. In the state, it is divided individually so as to be spaced apart by a certain distance, and the structure is continuously arranged laterally while maintaining different heights.

In this case, in the production line, the prism sheet 50 may be arranged in multiple layers while maintaining the resistance of the prism patterns 51 to defect factors such as "foreign material" and "pitch error". The two objectives of "obtaining visibility and securing normal light efficiency" can be achieved at once.

Meanwhile, in the backlight unit 100 for a liquid crystal display device of the present invention having such a structure, first, light emitted from the lamp 10 is directly incident into the light guide plate 30 or reflected by the lamp cover 20. When incident on one side of the light guide plate 30, the light guide plate 30 transmits the incident light to the diffusion sheet 40 disposed on the front surface of the light guide plate 30.

Subsequently, the diffusion sheet 40 transmits the light incident from the light guide plate 30 to the prism sheet 50 disposed on its front surface, and the prism sheet 50 transmits the light incident from the diffusion sheet 40 to itself. Transfer to the protective sheet 60 is disposed in the front of the.

At this time, as described above, the prism sheet 50 of the present invention is "divided separately so as to be spaced apart a certain distance in a state in which the mountain 53 is maintained in a straight shape, and continuously horizontally while maintaining different heights. Since a plurality of prism patterns 51 constituting the “arranged structure” are provided, strong resistance to defect factors such as “foreign material” and “pitch error” can be maintained.

Thereafter, the protective sheet 60 transmits the light incident from the prism sheet 50 to the image panel 2 disposed on its front surface, so that appropriate image information desired by the user is displayed on the liquid crystal panel 2. Induce to help.

As described above, in the present invention, the shape of the prism patterns is improved to maintain the acid region of each prism pattern in a straight line, and the resistance of the prism patterns to the defective factor is normally maintained, thereby ensuring "uniform visibility" and "normal". It is possible to achieve two purposes, such as "ensure light efficiency."

The present invention has an overall useful effect in all kinds of liquid crystal display devices manufactured in the production line.

And while certain embodiments of the invention have been described and illustrated, it will be apparent that the invention may be embodied in various modifications by those skilled in the art.

Such modified embodiments should not be understood individually from the technical spirit or point of view of the present invention and such modified embodiments should fall within the scope of the appended claims of the present invention.

As described in detail above, in the sheet assembly of the backlight unit for a liquid crystal display device according to the present invention, while the acid of the prism patterns formed on the surface of the prism sheet is kept in a straight shape, the sheet assemblies are separately divided so as to be spaced apart from each other. The heights of the divided prism patterns are diversified, and the prism patterns are aligned in a predetermined direction so that the mountains formed in the prism patterns are slightly twisted left and right.

When the present invention is practiced, the production line can maintain the acid regions of each prism pattern in a straight line while maintaining the resistance of the prism patterns to defect factors such as "foreign material" and "pitch error". It can achieve two purposes at once, such as securing uniform visibility and securing normal light efficiency.

Claims (4)

A diffusion sheet disposed on a front surface of the light guide plate and diffusing light rays output from the light guide plate; A prism sheet disposed on the front surface of the diffusion sheet, the prism sheet adjusting an output angle of light beams passing through the diffusion sheet in a state in which a prism pattern having a triangular prism shape formed with a peak and a valley is formed; Is disposed on the front of the prism sheet, including a protective sheet for preventing damage to the prism sheet, The prism patterns are individually divided so as to be spaced apart by a predetermined distance while keeping the acid in a straight shape, and maintain different heights, and are arranged in the longitudinal direction so that the mountains are twisted from side to side, and arranged horizontally. A sheet assembly of a backlight unit for a liquid crystal display device. 2. The sheet assembly of claim 1, wherein the prism sheet has a structure in which two or more sheets are continuously stacked. The sheet assembly of claim 2, wherein the prism patterns formed on each layer of the prism sheet have an arrangement structure perpendicular to each other for each layer. Base surface; Arranged on the base surface, in the form of a triangular prism shape formed with a straight line extending in a straight state, comprising a plurality of prismatic patterns separated by the valley, The prism patterns are individually divided to be spaced apart by a predetermined distance, maintain different heights, and are arranged in the longitudinal direction of the base surface such that the mountains are twisted from side to side, and are continuously arranged in the transverse direction of the base surface. Prism sheet of the backlight unit for a liquid crystal display device.