JPH0821917A - Light transmission plate for liquid crystal display - Google Patents

Abstract

PURPOSE:To provide a light transmission plate for liquid crystal display which can be easily viewed, which is uniformized and whose luminance is high by performing fine projecting and recessing work for diffusing light to the reflecting groove of the light transmission plate so as to obtain a diffusing reflecting surface without separately providing a diffusing plate outside the light transmis sion plate. CONSTITUTION:As to this light transmission plate for liquid crystal display in which plural reflecting grooves 2 are provided on one surface of the light transmission plate 1 at a specified interval, and in which a space between the adjacent reflecting grooves 2 is a flat surface 10, the reflecting surface 2a of the reflecting groove 2 is the diffusing reflecting surface having the fine projecting and recessing parts, and the flat surface 10 is a mirror surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a plurality of reflecting grooves formed on one side of a liquid crystal display light guide plate used for a liquid crystal display or the like, and a light beam incident from a light source along the plate surface of the light guide plate is reflected in each reflecting groove. The present invention relates to a light guide plate for a liquid crystal display, which is adapted to transmit diffusely reflected light in front of a plate surface by hitting the formed diffusely reflecting surface.

[0002]

2. Description of the Related Art The characteristics required for a light guide plate used in a liquid crystal display are to increase the light utilization rate of a light source and increase the brightness of light transmitted to the front surface of the light guide plate. It is to exhibit uniform brightness over the entire area.

In a recent liquid crystal display or the like, a light source is installed on the side of the light guide plate in order to make the device thin. However, the light incident along the plate surface is directed toward the front surface of the light guide plate. In order to transmit light to a transparent light guide plate, a light guide plate itself has a reflecting function without using a separate reflecting plate.

As shown in FIGS. 10 and 11, an example of the light guide plate 20 is a tapered transparent plate 21a having a triangular cross section with a vertical angle of 45 ° on each side and a total of 90 ° on one side as shown in FIG. , 21a are formed at predetermined intervals along an arcuate trajectory.

When a light source 22 (CFL) is applied to the light guide plate 20 from the horizontal side of the plate surface, light 23 from the light source 22 enters along the plate surface and the inclined surface 21 of each groove 21.
By reflecting the light by hitting a, it is transmitted through the plate surface of the light guide plate 20.

[0006]

In the above light guide plate 20, the inclined surface 21a which functions as a reflecting surface is formed at 45 °. This is because the 45 ° inclined surface 21a most efficiently reflects and transmits the incident light 23 from the light source 22 in front of the plate surface.

However, in the conventional light guide plate 20 as described above, the inclined surface 21a of the reflection groove 21 forms a mirror surface and exhibits a higher luminance than the surroundings, and a stripe pattern of light appears on the entire plate surface. There was a drawback that it became difficult to see.

This can be solved by providing a diffusing plate on the front surface of the light guide plate 20, but the installation of this diffusing plate is time-consuming and costly, which is against the thinning of the device. .

The present invention has been made in view of the above circumstances. Instead of separately providing a diffusing plate outside the light guide plate, fine concavo-convex processing for diffusing light into the reflection groove of the light guide plate is performed. The purpose of the present invention is to provide a high-brightness light guide plate for liquid crystal display, which is easy to visually see, by canceling the light stripe pattern that has appeared in the conventional light guide plate by applying the above-mentioned to a diffuse reflection surface.

Further, according to the present invention, the flat surface between the adjacent reflection grooves is made into a mirror surface, so that the light diffusion effect due to the reflection surface of the reflection groove being a diffuse reflection surface is not deteriorated, and the light guide plate of the light guide plate is not deteriorated. An object of the present invention is to provide a light guide plate for a liquid crystal display with improved brightness.

[0011]

In order to solve the above-mentioned problems, a liquid crystal display light guide plate of the present invention is provided with a plurality of reflection grooves on one surface of the light guide plate at predetermined intervals, and between the adjacent reflection grooves. In the liquid crystal display light guide plate having a flat surface, the reflective surface of the reflective groove is a diffuse reflective surface having fine irregularities, and the flat surface is a mirror surface.

Further, it is preferable that the flat portion formed in the reflection groove is a mirror surface.

Further, it is preferable that the reflection groove is gradually deepened as the distance from the light source provided on the side of the light guide plate increases.

It is preferable that the width of the flat surface is gradually narrowed as the distance from the light source provided on the side of the light guide plate increases.

Further, it is preferable that the diffuse reflection surface is formed by sandblasting the reflection surface of the reflection groove.

Further, it is preferable that the diffuse reflection surface is formed by applying metal particles to the reflection surface of the reflection groove.

[0017]

In the above-described structure of the present invention, since the reflecting surfaces of the plurality of reflecting grooves formed on one surface of the light guide plate are diffuse reflecting surfaces having fine irregularities, the light is incident along the plate surface of the light guide plate. The light from the light source hits these diffuse reflection surfaces,
Since it diffuses light and transmits it through the plate surface, the stripe pattern of light that has been generated in the past is eliminated, and the light from the light source efficiently transmits through the plate surface in a diffused state and the brightness of the entire light guide plate It becomes possible to improve.

Further, in the light guide plate of the present invention, since each flat surface between the adjacent reflection grooves is a mirror surface, diffuse reflected light does not occur on this flat surface, so that diffuse reflected light from the reflecting surface is generated. Therefore, it is possible to effectively exhibit the light diffusion effect of the reflecting surface without being interfered with by the reflected light from the flat surface.

Further, since only the reflecting surface of the reflecting groove is the diffuse reflecting surface as described above, the adjustment of the reflecting groove becomes easy.

That is, in the light guide plate, the amount of light tends to be weakened as the distance from the light source increases, but in order to compensate for such a defect by adjusting the reflection groove, individual reflection grooves are provided on the side of the light guide plate. By increasing the depth of the light guide plate or gradually narrowing the width of the flat surface, the transmission amount of diffuse reflected light on the entire plate surface of the light guide plate can be averaged, thereby making the brightness of the light guide plate uniform. .

[0021]

Embodiments of the present invention will be described with reference to the drawings.

First, a light guide plate having a linear orbital reflection groove will be described.

The light guide plate 1 shown in FIG. 1 is formed by forming a plurality of reflective grooves 2 having a linear trajectory at a predetermined interval on a transparent plate material such as plastic, and a light source 3 such as a CFL has two light guide plates 1 facing each other. The lateral installation complements the disadvantage that the amount of light weakens as the distance from the light source 3 increases.

FIG. 2 partially shows a cross section orthogonal to the reflection groove 2 of the light guide plate 1 of FIG. On one surface of the light guide plate 1, a plurality of reflection grooves 2 each having a trapezoidal cross section and having inclined reflection surfaces 2a, 2a on both sides of the inner flat end 2b are formed at predetermined intervals. Flat surfaces 10, 10 ... Are provided between the two.

In the light guide plate 1, the reflecting surfaces 2a, 2a of the respective reflecting grooves 2 are subjected to sandblasting or unevenness processing with metal particles to form the reflecting surface 2a as a diffuse reflection surface having fine unevenness. The flat surface 10 is a mirror surface without unevenness.

It should be noted that the reflection surface 2a is processed to have irregularities and the flat surface 1 is processed.
The method of mirror finishing of 0 will be described later.

According to such a light guide plate 1, the light 3a emitted from the light sources 3 and 3 which are installed opposite to each other on two sides of the light guide plate 1.
From the both sides of the light guide plate 1 to the inside along the plate surface, hit the both side reflection surfaces 2a, 2a of each reflection groove 2, and the reflected diffused light 1
2, the light passes through the transparent surface 11 and is transmitted from the plate surface of the light guide plate 1 outward with high brightness.

The reflection groove 2'of the light guide plate 1'shown in FIG.
The light source 3 is installed on one side of the light guide plate 1 ′, although the same linear trajectory is used. The light guide plate 1 ′ is made of a transparent plastic material, and a reflection groove 2 ′ is formed on one surface of a tapered plate material having a plate thickness that becomes thinner as the distance from the light source 3 increases, and a reflection surface 2 a ′ having a semicircular cross section with a linear trajectory. Are formed at predetermined intervals.

Also in the light guide plate 1'having the reflecting surface 2a 'having a semicircular cross section, the reflecting surface 2a' is sandblasted as described later, or is provided with a fine uneven surface made of metal particles. Semi-circular reflective surface 2
A'is a diffuse reflection surface and the flat surface 10 is a mirror surface.

However, since the light guide plate 1'is provided with the light source 3 on one side thereof, the light source 3 is provided more than the one having the light sources 3, 3 on two sides as shown in FIG. Although the amount of light becomes weaker as the distance from the light source 3 increases, the height of the reflection groove 2'is gradually increased as the distance from the light source 3 increases, or the width between the adjacent reflection grooves 2'and 2 '(the width of the flat surface 10) becomes narrower. Therefore, it is preferable that the diffuse reflection efficiency per unit area at the position away from the light source 3 is gradually increased to make the brightness of the entire light guide plate 1 uniform.

Next, referring to FIG. 4 to FIG. 9, a light guide plate 1 "having a reflection groove 2" having an arcuate orbit will be described. In the following description, the reflection groove 2 ″, the reflection surface 2 a and the flat portion 2 b
The numbers on the flat surface 10 are the same as those on the corresponding portions of the light guide plate 1 ″, the master plate 7 and the mold 8.

In the light guide plate 1 "shown in FIG. 4, a plurality of reflective grooves 2" having arcuate orbits are formed at a predetermined interval on a transparent plate material such as plastic, and the plate thickness is set to one side of the light guide plate 1 ". The taper shape is reduced as the distance from the installed light source 3 increases.

Lines 1, 2, 3, and 4 in FIG.
The center line of the light guide plate 1 "is set to LINE1, and LINE2 and LINE are set at 10 cm intervals from here to both ends in the width direction.
3 and LINE 4 are taken, and an imaginary line is drawn in which each LINE intersects the arc locus of the reflection groove 2 ″ substantially perpendicularly. Further, FIGS. 5 (a) and 5 (b) show the reflection groove in each LINE. The cross-sectional shape of 2 "is sequentially shown.

In order to form the reflection groove 2 ″ having an arcuate trajectory on such a light guide plate 1 ″, as shown in FIG. 6, a tool 4 made of cemented carbide is mounted on an NC machine tool, and the tool 4 is used. The cutting process is started from one side of the master plate 7 and moved to the other end of the master plate 7 while drawing an arc trajectory.

In FIG. 6, the shape of the cutting tool 4 is the cutting edge 4 as shown by 4'when the cutting tool 4 is viewed in the direction of the line AA.
a forms 90 °, and the side surface of the cutting edge 4a has a trapezoidal shape as indicated by 4 "when the cutting tool 4 is viewed in the BB line direction, and the cutting edge 4a has a straight portion of a certain length at its tip. It is a thing.

When an arcuate trajectory is drawn while cutting the reflection groove 2 "with such a cutting tool 4, the cutting edge 4a becomes LINE.
Since it moves on the arcuate orbit while always facing a constant vertical direction with respect to 1, the cutting edge 4a of the cutting tool 4 moves while being inclined with respect to the arcuate orbit as it moves away from LINE1. As a result, a flat portion 2b is formed between the reflecting surfaces 2a, 2a on both sides, and the width of the flat portion 2b (the width of the alternate long and short dash lines 5 and 5 in FIG. 6) gradually increases as the distance from the LINE1 increases.

FIG. 7 shows a sectional view of the master plate 7 corresponding to the LINE 4 position in FIG. 4 where the width of the flat portion 2b is widest. As shown in the figure, a plurality of reflection grooves 2 "are formed at a predetermined interval on the master plate 7 by the above processing, and a flat surface 10 is formed along the plate surface between adjacent reflection grooves 2" and 2 ". The reflecting grooves 2 ″ are formed with inclined reflecting surfaces 2 a, 2 a on both sides thereof and a flat portion 2 on the bottom.
b are formed.

The mold 8 shown in FIG. 8 formed by such a master plate 7 is molded, and then the light guide plate 1 "shown in FIG. 9 is molded by this mold 8.

FIG. 9 shows the LIN of the light guide plate 1 "which is the final product.
A partial cross section at E4 is shown. A plurality of reflection grooves 2 "are formed on one surface at predetermined intervals, a flat portion 2b is formed between the reflection surfaces 2a, 2a, and between the reflection grooves 2", 2 ". A flat surface 10 is formed along the plate surface.

In the present invention, the light guide plate 1 as described above,
1 ', 1 "reflection grooves 2, 2', 2" reflection surfaces 2a, 2
In order to perform sandblasting on a ′, for example, when performing sandblasting on the light guide plate 1 ″ in FIG. 9, one or both of the reflecting surfaces 2a of the master plate 7 in FIG. 7 and the mold 8 in FIG. Fine sand particles 9 mixed in high-pressure air are vertically applied to one or both of the reflecting surfaces 2a or one or both of the reflecting surfaces 2a of the light guide plate 1 ″ itself of FIG. At this time, the sand particles 9 form the flat portion 2a and the flat surface 1
Since it hits in an oblique direction with respect to 0, unevenness due to the sand particles 9 is unlikely to occur in these flat portions.

However, in the present invention, the flat surface 10 of any one of the master plate 7, the mold 8 and the light guide plate 1 ″ is subjected to mirror surface processing such as bite processing, and each flat surface 10 is processed.
To a mirror surface. This mirror surface processing may be performed on the flat portion 2b in the reflection groove 2 ". By doing so, the diffuse reflection light is generated only in the individual reflection surface 2a in the light guide plate 1".

Next, the various reflection grooves 2, 2 ', and
In order to form a fine uneven surface of metal particles on the 2 ″ reflecting surfaces 2a, 2a ′, for example, a mold 8 as shown in FIG.
Metal particles (fine metal powder) such as gold or silver on the reflective surface 2a of
When the light guide plate 1 ″ is molded from the mold 8, the above metal particles are attached to the reflecting surface 2a of the light guide plate 1 ″.

Metal particles may be attached to the reflecting surfaces 2a, 2a 'of the light guide plates 1, 1'which are final products by printing, painting, vacuum deposition or the like.

Also, the reflecting surface 2 of the light guide plate 1, 1 ', 1 "
When the metal particles are directly applied to a and 2a ′, the metal particles are mixed in a fluid adhesive and the solvent is
A method may be used in which the reflecting surfaces 2a, 2a 'are covered with the entire surface of the reflecting surfaces 2a, 2a' of 1 ', 1 "by flowing down along the inclined surface or the arc surface.

Further, from the mold 8 to the light guide plates 1, 1 ', 1 "
At the time of molding the light guide plate 1, 1 ', 1 "of the reflective surface 2
You may make it form the coating layer which mixed the metal particle in the surface layer of a, 2a '.

The formation of the uneven surface by the metal particles is performed only on the reflecting surfaces 2a and 2a 'and not on the flat end 2b or the flat surface 10, and the flat end 2b or the flat surface 10 is originally formed. It is better to keep the mirror surface.

Further, in the light guide plate 1 ″, in order to compensate for the defect that the light amount weakens as the distance from the light source 3 increases, the light guide plate 1 ″ also has the depth adjustment of the reflection groove 2 ″ and the adjacent reflection groove 2 ″. The width between "2" is adjusted.

As a method thereof, at the stage of forming a plurality of reflection grooves 2 ″ on the master plate 7, the depth of each reflection groove 2 ″ is gradually increased as the distance from the light source 3 side is increased,
The depth of the reflection groove 2 ″ of the master plate 7 is made constant, and the distance between the reflection grooves 2 ″ and 2 ″ is gradually narrowed as the distance from the light source 3 increases, or the reflection groove 2 of the master plate 7 increases as the distance from the light source 3 increases. It is advisable to gradually increase the depth of "" and gradually decrease the interval between the reflection grooves 2 ", 2".

Furthermore, since the light guide plate 1 ″ has a tapered shape in which the plate width is reduced as the distance from the light source 3 increases, the frequency of diffuse reflection per unit area at the position away from the light source 3 increases and the entire plate surface is increased. The brightness can be made uniform.

[0050]

As described above, according to the light guide plate for liquid crystal display of the present invention, a plurality of reflection grooves formed on one surface of the light guide plate are diffused and reflected by sand blasting or fine irregularities formed by metal particles. Since it is a surface, the light from the light source can be transmitted through the plate surface as diffuse reflection light,
As a result of averaging the amount of light transmission over the entire plate surface and improving the light utilization efficiency, it is possible to improve the brightness of the entire light guide plate.

Further, according to the liquid crystal display light guide plate of the present invention, since each flat surface between the reflecting grooves is a mirror surface, diffuse reflection light generated in the reflecting grooves is not lost. As a result, the diffuse reflection effect can be maximized, which contributes to the improvement of the brightness of the light guide plate.

Further, the diffused reflection light is generated only on the reflection surface of the light guide plate, which facilitates the adjustment of the reflection groove.
Each reflection groove is made deeper as it goes away from the light source provided on the side of the light guide plate, or the width of the flat surface is gradually narrowed to make the transmission amount of diffuse reflected light uniform over the entire light guide plate. This makes it possible to make the brightness of the entire light guide plate uniform.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a state in which light sources are provided on two opposite sides of a light guide plate according to the present invention in which a plurality of linear orbital reflection grooves are formed.

FIG. 2 is a schematic partial cross-sectional view showing a cross-sectional situation at an arbitrary position orthogonal to the reflection groove of the light guide plate of FIG.

FIG. 3 is a schematic partial cross-sectional view in which light is incident from a light source on one side of a light guide plate according to the present invention in which a plurality of reflection grooves having a semicircular cross section are formed.

FIG. 4 is a schematic plan view showing a situation in which a light source is provided on one side facing a light guide plate according to the present invention in which a plurality of arcuate orbital reflection grooves are formed.

5 (a) to 5 (d) are LINE1 in FIG.
It is a schematic sectional drawing which shows the difference of the inclined surface angle of the reflection groove corresponding to 2, 3, and 4, and the shape change of the bottom part of a reflection groove.

FIG. 6 is a schematic partial plan view showing a master plate in which a reflection groove having an arcuate track is formed by a bite machining by an NC machine tool in the present invention.

FIG. 7 is a schematic partial cross-sectional view taken along the LINE 4 of FIG. 4 showing a situation where the inclined surface of the reflection groove of the master plate is sandblasted in the present invention.

FIG. 8 is a schematic partial cross-sectional view taken along the LINE 4 of FIG. 4 showing a situation where the inclined surface of the reflection groove in the mold is sandblasted in the present invention.

9 is a schematic partial cross-sectional view showing a reflection and diffusion state in which light from a light source is incident on a cross-section part along LINE4 of the light guide plate of FIG.

FIG. 10 is a plan view showing a state in which a light source is provided on a conventional light guide plate.

11 is a partial cross-sectional view showing a cross-sectional situation of a reflection groove of the conventional light guide plate shown in FIG.

[Description of sign]

1, 1 ', 1 "... light guide plate, 2', 2" ... reflection groove, 2
a ... flat surface, 2b ... flat part, 3 ... light source, 3a ... incident light from light source, 4 ... bite, 4a ... bite edge, 4b ... bite inclined surface, 7 ... master plate, 8 ... die, 9 ... sand particles of sandblast, 10 ... flat surface between reflection grooves, 11 ... transmission surface, 12 ... reflected diffused light.

Claims (6)

[Claims] 1. A plurality of reflection grooves (2) on one surface of a light guide plate (1).
Are provided at a predetermined interval, and the adjacent reflection grooves (2, 2) are provided.
In the liquid crystal display light guide plate having a flat surface (10) between the reflecting grooves (2), the reflecting surface (2a) of the reflecting groove (2) is a diffuse reflecting surface having fine irregularities, and the flat surface (10) is a mirror surface. A light guide plate for a liquid crystal display, characterized in that 2. The light guide plate for liquid crystal display according to claim 1, wherein the flat portion (2b) formed in the reflection groove (2) is a mirror surface. 3. The liquid crystal display according to claim 1, wherein the reflection groove (2) is gradually deepened as the distance from the light source (3) provided on the side of the light guide plate (1) increases. Light guide plate. 4. The liquid crystal according to claim 1, wherein the width of the flat surface (10) is gradually narrowed as the distance from the light source (3) provided on the side of the light guide plate (1) increases. Light guide plate for display. 5. The light guide plate for a liquid crystal display according to claim 1, wherein the diffuse reflection surface is formed by sandblasting the reflection surface (2a) of the reflection groove (2). 6. The light guide plate for a liquid crystal display according to claim 1, wherein the diffuse reflection surface is formed by applying metal particles to the reflection surface (2a) of the reflection groove (2).