KR20050007828A - A light guide panel having engraved pyramidal shapes on the bottom surface and the systems thereof, wherein one edge of the pyramidal shape is confroting the side positioned-light source - Google Patents

Abstract

PURPOSE: A light guide panel is provided to focus light onto a front surface of an LCD panel by changing a light path to the front surface by using an engraved pyramidal shape at a bottom surface thereof. CONSTITUTION: A light guide panel(12') for a back light unit having a light source(10) is to receive light emitted from the light source at a side and guides the incident light to an upper surface. The light guide panel includes a plurality of engraved pyramidal shapes(30) formed at a bottom surface. One edge(32) of the engraved pyramidal shape is arranged to confront the light source. The engraved pyramidal shape is to be at least one of a trigonal pyramidal shape and a quadrangular pyramidal shape.

Description

LIGHT GUIDE PANEL HAVING ENGRAVED PYRAMIDAL SHAPES ON THE BOTTOM SURFACE AND THE SYSTEMS THEREOF, WHEREIN ONE EDGE OF THE PYRAMIDAL SHAPE IS CONFROTING THE SIDE POSITIONED-LIGHT SOURCE}

The present invention relates to a light guide plate used in a backlight unit of an LCD system and a system using the same, and more particularly, by converting a light path to direct more light toward an upper surface of the light guide plate by a concave polygonal shape formed on the bottom surface. It relates to a light guide plate structure and a system using the same.

In general, a liquid crystal display or LCD cannot emit light by itself, and thus a backlight unit must be separately provided on the back side thereof.

There are two types of backlight units used in LCDs: direct type and side type. In electronic devices that need to be thin, it is common to use a side type backlight unit in which a CCFL or a white LED light emitting element is disposed on a side of a light guide plate.

1 illustrates a conventional configuration of a side type backlight unit, and FIG. 2 illustrates a part of the configuration of FIG. 1 in a perspective view.

The conventional side type backlight unit includes a light guide plate 12 that receives and guides the light emitted from the light source 10, and a reflector plate that is positioned below the light guide plate and reflects light traveling toward the bottom and side surfaces of the light guide plate in an upward direction ( 14), the first diffusion sheet 18 for uniformly diffusing the light directed upwardly through the light guide plate throughout the LCD panel 16, and the traveling direction of the light through the first diffusion sheet 18; First and second prism sheets 20 and 22 for condensing in the front direction, that is, in the Z-axis direction (hereinafter, referred to as “front condensing” in the Z-axis direction), and diffusing light through the prism sheet, It is provided with a second diffusion sheet 24 for protecting the light, and also comprises a lamp housing 26 for reflecting the light of the light source 10 to the light guide plate (12). Coordinates are shown on the left side, with the X-axis pointing out from the ground.

When the light emitted from the light source 10 through the light guide plate 12 in the upper direction passes through the first diffusion sheet 18, the light diffuses in the X-axis and Y-axis directions, and thus the front brightness is sharply dropped. The prism sheets 20 and 22 are used to condense the light to the front to increase the backlight brightness of the LCD panel 16. The prism sheet is formed with a groove-shaped micro prism on the base material.

The prism sheet is constructed by laminating two sheets of forward prism sheets (20, 22). Since each prism sheet can concentrate light only in one axis direction, the micro prisms are perpendicular to each other, as shown in FIG. 2, in order to totally focus each component of light spreading in at least the X axis direction and the Y axis direction in the Z axis direction. The two prism sheets 20, 22 arranged are required to obtain a desired viewing angle profile in the Z-axis direction.

To illustrate this in more detail, a schematic view of the viewing angle profile of FIG. 2 will be described. 3 shows how much light passing through each prism sheet is concentrated in the Z-axis direction. The greater the central concentration, the more the front condensation of the light, that is, the Z-axis direction is improved.

The profile A of the light passing through the first prism sheet 20 improves the front condensation in the Y-axis direction but still does not improve the front condensation in the X-axis direction, which indicates that the microprism of the prism sheet 20 As it is arranged along the X-axis direction, it is natural as a result of the optical. Therefore, this light must pass through the prism sheet 22 in which the microprism is arranged along the Y-axis direction, and finally create a viewing angle profile C with a central concentration. Profile B is shown with reference to the viewing angle when it is assumed that light passes only through the prism sheet 22.

The prism sheet is manufactured and supplied almost exclusively by US 3M, and is one of the components that most influence the cost of the backlight unit. In addition, it is natural that the more the light passes through a certain layer, the higher the absorption becomes and the luminance becomes weaker.

The conventional structure of FIG. 1 has two problems of using the prism sheet for the above-described reasons, resulting in an increase in light loss and an increase in manufacturing cost.

The present invention seeks to solve this problem of the prior art.

The present invention aims to improve the disadvantage of using the two prism sheets described above, specifically, to provide a light guide plate structure in which only one prism sheet is used or not required at all.

It is another object of the present invention to provide a structure of a light guide plate that emits light emitted from a side light source to the light guide plate side and efficiently condenses the light path to the front surface of the LCD panel by using a concave polygonal pyramid below.

Another object of the present invention is to provide a configuration of an LCD system having improved front luminance than a conventional system using the light guide plate and an electronic apparatus using the LCD system as a display unit.

1 is a view showing the structure of a conventional backlight unit.

2 is a perspective view of the structure of FIG.

3 is a view showing a viewing angle profile in the Z-axis direction with respect to the conventional backlight unit of FIG.

4 is a view showing the arrangement of a light source and a light source inside the light guide plate of the present invention.

5 is a side view of the structure of FIG.

6 is a view showing a viewing angle profile in the Z axis direction for the backlight unit of the present invention.

7 is a schematic diagram showing an optical path conversion substrate for the polygon pyramid of the present invention.

8 is a schematic diagram showing an optical path conversion substrate for a conventional microprism.

9 is a plan view of an InP substrate having a negative triangular pyramid shape.

10 is a side view of an InP substrate having a negative triangular pyramid shape.

11 is a schematic diagram showing a state in which a plurality of processed crystal substrates are connected.

12 is a view of a light guide plate including an embossed protrusion on a lower surface thereof.

FIG. 13 is a view of a light guide plate including an embossed or intaglio lens portion on a lower surface thereof.

Description of the main parts of the drawing

10: light source 12, 12 ', 12 ", 13: light guide plate

14: reflector 20, 22: prism sheet

30: Pyramid 32: Pyramid corner opposite to light source

The light guide plate for the backlight unit of the present invention for achieving the above object includes a light source and a light guide plate that receives the light emitted from the light source from the side to the upper surface, a plurality of negative polygonal pyramid at the bottom of the light guide plate It is formed, characterized in that one corner of the negative polygonal pyramid is arranged to face the light source, the negative polygonal pyramid may be at least one of a triangular pyramid, a square pyramid.

The light guide plate may further include a plurality of light scattering means, for example, an embossed protrusion formed on the bottom surface of the light guide plate, an ink pattern formed on the bottom surface of the light guide plate, or a step of 3 μm to 8 μm formed on the top surface of the light guide plate. Unevenness is one example.

The present invention also relates to an LCD system having a light guide plate having the above-described features and an electronic apparatus using the LCD system as a display unit, such as a mobile phone, a TV, a computer, and the like.

Hereinafter, with reference to the drawings will be described embodiments of the present invention;

4 is a perspective view of an arrangement state between the light guide plate 12 ′ and the light source 10 of the present invention, and FIG. 5 is a side view of the light guide plate 12 ′. For convenience, both drawings show only the light source and the light guide plate. It is shown transparently.

In the lower surface of the light guide plate 12 'of the present invention, a polygonal intaglio shape 30 is formed, and the corner 32 of the polygonal pyramid intaglio is necessarily disposed to face the light source 10, which is one of the most important features of the present invention. One.

FIG. 6 shows a viewing angle profile showing the front condensing degree of the X-axis and Y-axis components of light passing through the light guide plate 12 'of the present invention on the X-Y plane. According to FIG. 6, when one side of the pyramid is disposed toward the light source with two surfaces on the left and right sides thereof, the two surfaces collectively focus on both the X-axis and Y-axis components of light emitted from the light source and incident into the light guide plate. The viewing angle profile D shows that the function is performed. For reference, profiles A, B, and C are shown for comparison as the conventional viewing angle profiles of FIG. 2.

The viewing angle profile D of the light passing through the light guide plate of the present invention shows a circular condensing degree. In addition, since D is slightly wider than C, the front viewing angle profile of the light passing through the two conventional prism sheets, the direction is slightly reduced. However, since the light does not pass through the prism sheet, the actual luminance is lower than that of the conventional configuration. Higher.

FIG. 7 illustrates an optical path of light reflected by the polygonal pyramid 30 of the present invention, and FIG. 8 illustrates an optical path for light of the same angle reflected by the conventional microprism 50.

For reference, total reflection of light is a phenomenon in which light is reflected without being refracted when the light enters a material having a high refractive index from a high refractive index to a material having a low refractive index. It is one of the important factors that determine the amount of total reflection light. The polygonal pyramids 30 and the microprism 50 of the present invention all convert the optical path using this total reflection phenomenon.

In the drawing, the Y-axis component of the light reflected by the microprism 50 is focused on the front, but the X-axis component does not show the direction as described above. However, it can be seen that the light reflected by the polygonal pyramid 30 of the present invention can be totally condensed to some extent on both the X-axis and the Y-axis depending on the geometric arrangement with the pyramid face.

To explain this differently, when the light source is subdivided in the longitudinal direction and each is viewed as a point light source, the farther away the polygonal pyramid and the point light source are, the light emitted from the point light source (a, d) is reflected from the plane of the polygonal pyramid, and the upper Z It can be seen in the drawing that the degree of axial direction is greater than the lights b, c originating from the point light source relatively close to the polygonal pyramid.

In contrast, the conventional microprism 50 finds that the reflected Z-axis component of the light (e, h) of the point light source is far from the point (g, f) of the point light source close to the specific reflection point on the surface thereof. Can be. Since the amount of light of the point light sources arranged to the left and right is generally larger than the light of the point light source located directly in front of the reflection point, the polygonal pyramid of the present invention is a structure that can efficiently focus more light than the conventional microprism. can do.

The structure of the prism having the polygonal pyramid shape of the present invention is possible in the triangular pyramid, the pentagonal pyramid, the hexagonal pyramid, and all other pyramids as well as the illustrated square pyramid.

Hereinafter, an embodiment of a process for making the light guide plate structure of the present invention will be described.

First, a process for forming the square pyramid intaglio shown below is as follows.

A silicon nitride (Si3N4) film having a thickness of about 1000 to 3000 mW is formed on the surface of the silicon wafer having a (100) plane by using a PECVD process or the like.

Then, the photoresist is applied thereon, followed by a softbaking process of heat treatment at around 100 degrees, and then the mask is raised and exposed. In this case, if the mask is exposed by rotating the substrate 45 degrees on the basis of the flat zone of the semiconductor wafer, an intaglio polygonal light guide plate having an edge toward the light source can be easily created later. However, it is not necessary to perform a 45-degree tilting exposure at this stage, and later, when cutting the wafer or forming a nickel stamp, a mold having a tilted angle of 45 degrees may be formed, and the stamp itself may be tilted by 45 degrees to perform the injection process. It may be natural.

After exposure, the PR is etched in the etchant to expose the silicon nitride film, and then the silicon nitride film is removed by dry etching again to expose the silicon surface of the portion where the polygonal pyramid is to be formed.

The exposed silicon is then subjected to an anisotropic etch with KOH solution. Since the etching rate of the (100) and (111) planes of the silicon crystals differs to 100: 1, etching with a KOH solution creates a pyramidal quadrangular pyramid-shape inside the silicon crystal plane. This step is the stage of fabricating the silicon disc to make nickel stamp. Pyramidal anisotropic etching of the silicon is generally well known and detailed description thereof will be omitted.

The method of manufacturing a nickel stamp uses the conventional nickel electroplating method. First, nickel, chromium, or gold is thinly deposited on a silicon wafer having a square pyramid by a sputtering process to form an electrode to be used for electroplating. Then, a nickel layer having a thickness of 300 micrometers or more is plated with a current of about 3 A at about 100 mA. At this time, as the nickel plating solution, a nickel sulfamate plating solution that can reduce internal stress can be used.

After nickel plating, it is separated from the silicon wafer to complete the nickel stamp in which the engraved square pyramids engraved on the silicon wafer are embossed. Then, the stamping process can be used to produce a light guide plate having a negative square pyramid on one side.

The present invention can also use a triangular pyramid intaglio instead of the square pyramid, the process for making this triangular pyramidal intaglio is as follows.

First, an InP or GaAs substrate having a {111} plane having a Zinc-Blende structure is prepared, and then a SiO 2 film having a thickness of about 100 nm is deposited on the substrate. Then, the mask is formed by circularly perforating the portion to form the triangular pyramid, and then removes the SiO2 film of the portion through a general exposure process.

Subsequently, the substrate was placed in a vacuum chamber and then dry-etched at 500 ° C. and 50 Torr with a mixed gas of hydrogen gas, HCl gas, and PH3 gas. Three {110} planes appear. When the etching continues and these three surfaces meet, the etching is almost stopped, and a triangular pyramid intaglio surrounded by three surfaces with {110} surfaces is formed on the substrate surface.

9 and 10 illustrate a plan view and a cross-sectional view of the substrate having the triangular pyramid intaglio, respectively. The three sides of the intaglio are all {110} planes, which are in contact with the (111) plane at an angle of 35.3 degrees. And the edge where the two {110} planes meet meets the (111) plane and 19.5 degrees.

After forming the triangular pyramidal intaglio on the surface of the substrate, a process of manufacturing a nickel stamp and a process of manufacturing a light guide plate having a triangular pyramidal intaglio are the same as or similar to those described above, and thus a detailed description thereof will be omitted. The arrangement of the backlight unit by arranging one side of the triangular pyramid toward the light source is the same as the above-described square pyramid.

Another embodiment of the present invention is that the polygonal pyramid is composed of an irregular polygon such as a rectangle, not a regular polygonal pyramid, and is also arranged so that the edges face toward the light source. In the case of atypical polypyramids, it is possible to have a structure that is not pointed at the top.

Since the present invention only obtains a light guide plate having a size limited to the width of the silicon wafer because a nickel stamp is made using a crystalline substrate such as a silicon wafer, a plurality of nickel stamps are assembled to fabricate a large size light guide plate of 15 inches or more. A large area nickel stamp is used.

Another method of manufacturing a large light guide plate is to join several wafers themselves, and then perform the anisotropic etching in this state to make a piece of nickel stamp. FIG. 11 schematically shows the shape of a crystal substrate in which four wafers are connected with their respective sides in contact. Since the process of making a nickel stamp on this is the same as the method mentioned above, detailed description is abbreviate | omitted.

In order for the light guide plate of the present invention to scatter light sufficiently, a plurality of scattering patterns may be reinforced on the surface together with the negative polygonal pyramid.

The scattering pattern may be a form in which a general ink pattern is printed on the lower part of the light guide plate by a screen printing method, or irregularities having a height difference of about 3 μm to 8 μm on the upper part of the light guide plate.

Another scattering pattern may use an embossed protrusion 70 protruding from the lower surface of the light guide plate 12 ″. FIG. 12 illustrates an embodiment thereof, and a method of forming the embossed protrusion 70 may be described. The simplest is to apply a thick PR back to the wafer surface where the polypyramids are primarily etched, then remove all the PR, leaving only the areas to be embossed, and then deposit nickel on them.

Then, when the substrate and the nickel stamp are separated, a nickel stamp is formed in which the embossment of the quadrangular pyramid and the intaglio of the PR structure are mixed together. After fixing the nickel stamp to the light guide plate extruder, the light guide plate raw material can be inserted and injected to form the light guide plate having the above-described embossed protrusions. The embossed protrusions can have various shapes as well as circular.

Another method of forming an embossed protrusion is a method in which a nickel stamp is made of a wafer on which only an intaglio polygonal pyramid is formed, and then the nickel stamp is etched with nitric acid to directly form grooves on the surface of the nickel stamp to form the embossed protrusion.

Another embodiment of the present invention for the easy diffusion of light is to form an intaglio or embossed hemispherical shape, or lens shape on the lower surface of the light guide plate together with the negative polygonal pyramid.

FIG. 13 illustrates a scattering means 80 having a shape protruding into the aforementioned lens shape together with the negative polygonal pyramid. This lens formation may be formed in an intaglio recessed shape as opposed to shown.

It is also possible to further form the relief protrusion in addition to the above structure.

Creating such an intaglio or embossed lens shape can also be made simply by using the photoresist described above. That is, after the polygonal pyramid shape is formed on the wafer, the photoresist may be coated so as to have a lens shape, and then a nickel stamp may be formed through a baking process or the like. Thereafter, the nickel stamp may be formed by transferring the shape of the surface of the primary nickel stamp with the secondary nickel stamp. Here, the secondary nickel stamp is produced by separating the nickel stamp formed on the primary nickel stamp by electroplating or the like again. In addition, it is also possible to make a third nickel stamp, which can be easily conceived by a person having an average knowledge of the present invention.

The present invention relates to a light guide plate having an intaglio polygonal pyramid, the corner of which is opposite to a light source, on its lower surface.

When the light guide plate is used, the front condensing of the two prism sheets can be performed at the same time as in the prior art, thereby reducing the light guide plate manufacturing cost and simplifying the assembly process and improving the stability of the system.

In addition, since the light does not pass through the prism sheet itself, the light is absorbed and the brightness is not reduced.

In addition, a large area light guide plate can be manufactured by stacking multiple wafers, and the light uniformity and scattering pattern of the polygonal pyramid can be implemented to enhance the uniformity of light.

Those skilled in the art having understood the various embodiments and technical spirit of the present invention will be able to easily create various modifications. However, it should be understood that these modifications also belong to the scope of the present invention.

Claims (14)

Light source, It includes a light guide plate for receiving the light emitted from the light source from the side to the upper surface, A plurality of negative polygonal pyramids are formed below the light guide plate, and one corner of the negative polygonal pyramid is disposed to face the light source. The light guide plate of claim 1, wherein the intaglio polygonal pyramid is at least one of a triangular pyramid and a quadrangular pyramid. The light guide plate of claim 1, wherein the light guide plate further comprises a plurality of light scattering means. The light guide plate of claim 3, wherein the light scattering means is an embossed protrusion formed on a lower surface of the light guide plate. The light guide plate of claim 3, wherein the light scattering means is an ink pattern formed on a lower surface of the light guide plate. The light guide plate according to claim 3, wherein the light scattering means is irregularities having a step of 3 μm to 8 μm formed on an upper surface of the light guide plate. The light guide plate of claim 3, wherein the light scattering means is any one of a protruding or engraved shape having a lens shape formed on a lower surface of the light guide plate. Light source, A light guide plate which receives light emitted from the light source from the side surface and directs the light toward the upper surface; A reflection plate disposed under the light guide plate to reflect the light exiting to the bottom surface of the light guide plate to be directed upward; It includes an LCD panel having a drive drive and a liquid crystal disposed on the light guide plate, A plurality of negative polygonal pyramids are formed at the bottom of the light guide plate, and one corner of the negative polygonal pyramid is disposed so as to face the light source. The LCD system of claim 8, wherein the intaglio polygonal pyramid is at least one of a triangular pyramid and a quadrangular pyramid. The LCD system of claim 8, wherein the light guide plate further comprises a plurality of light scattering means. The LCD system according to claim 10, wherein the light scattering means is an embossed protrusion formed on a lower surface of the light guide plate. 10. The LCD system of claim 8, further comprising a diffuser plate between the light guide plate and the LCD panel for evenly dispersing light from the light guide plate to the LCD panel. Light source, A light guide plate which receives light emitted from the light source from the side surface and directs the light toward the upper surface; A reflection plate disposed under the light guide plate to reflect the light exiting to the bottom surface of the light guide plate to be directed upward; An LCD panel including a driving drive and a liquid crystal disposed on the light guide plate, And a LCD system having a plurality of negative polygonal pyramids formed at a lower portion of the light guide plate and having one corner of the negative polygonal pyramid facing the light source as a display unit. In the light guide plate forming mold, A crystal template for light guide plate formation, characterized in that a plurality of crystal substrates having a plurality of negative polygonal pyramids formed on a surface thereof are formed in a state in which side surfaces are connected to each other.