JP2003098356A - Light transmission plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light transmission plate suppressing moire resulting from a relation between a pitch of pixels and a shape of the light transmission plate. SOLUTION: The light transmission plate 101 is placed along a front surface or a rear surface of a liquid crystal display panel 20. A plurality of curve shaped grooves 114 and edges 115 are formed on a surface of the light transmission plate 101 on the opposite side of a surface confronting the liquid crystal display panel 20, i.e., on the front surface 112. The shape of the groove 114 or the edge 115 may be optionally a sine wave shape or a shape of serration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate for illuminating a display panel such as a liquid crystal display panel, and more particularly to a light guide plate capable of suppressing moire.

[0002]

2. Description of the Related Art There is known a display device including a display panel such as a liquid crystal display panel and a light guide plate arranged along a front surface of the display panel, and a light source attached to a side surface of the light guide plate.
The light emitted from the light source is guided along the light guide plate. The front surface of the light guide plate is formed in a shape having a groove or a twill, and the light guided through the inside of the light guide plate hits the front surface of the light guide plate and is reflected to the back side to illuminate the display panel.
This allows the observer to see the display on the display panel via the light guide plate.

[0003]

Conventionally, by forming the grooves or the grooves formed on the front surface of the light guide plate at the same pitch as the pixel pitch of the display panel, it is possible to efficiently form a necessary portion, for example, an opening portion of a liquid crystal panel. By shining light on it, we try to obtain a bright display. However, a slight deviation between the pixel pitch of the display panel and the pitch of the grooves of the light guide plate may cause moire, which is a problem because it is visually noticeable.

It is an object of the present invention to provide a light guide plate capable of suppressing moire caused by the relationship between the pixel pitch and the shape of the light guide plate.

[0005]

A light guide plate of the present invention is a light guide plate arranged along the front surface or the back surface of a display panel, wherein a plurality of light guide plates are provided on the surface opposite to the surface facing the display panel. It is characterized in that a curved groove or a twill is formed.

According to this light guide plate, since a plurality of curved grooves or twill are formed on the surface of the light guide plate opposite to the surface facing the display panel, the relationship between the pixel pitch and the shape of the light guide plate can be obtained. It is possible to suppress the moiré derived from it. The display panel may be a liquid crystal display panel.

The grooves or the grooves may be formed at a pitch corresponding to the pixel pitch of the display panel. In this case, the pitch of the groove or the cross may be the same as the pixel pitch, or the pitch of the groove or the cross may be changed with the pixel pitch as a reference. By varying the groove or twill pitch,
Moire can be further suppressed.

The groove or the twill may be formed in a sine wave shape, or may be formed in a sawtooth shape.

The light guide plate may be arranged on the front side of the display panel.

Generally, when the light guide plate is arranged on the front side of the display panel, moiré is more likely to occur, so in this case, moiré can be suppressed more effectively.

In the light guide plate of the present invention, which is arranged along the front surface of the display panel, a curved groove or twill is formed on the surface of the light guide plate opposite to the surface facing the display panel. It is characterized by being

According to this light guide plate, since a plurality of curved grooves or twill are formed on the surface of the light guide plate opposite to the surface facing the display panel, the relationship between the pixel pitch and the shape of the light guide plate can be obtained. It is possible to suppress the moiré derived from it. Further, when the light guide plate is arranged on the front surface side of the display panel, moiré is more likely to occur, so that moiré can be effectively suppressed.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the light guide plate of the present invention will be described below with reference to FIGS.

FIG. 1 is a sectional view of a liquid crystal display device including the light guide plate of this embodiment, and FIG. 2 is a front view of the liquid crystal display device as seen from the front side.

As shown in FIGS. 1 and 2, the liquid crystal device includes a liquid crystal panel 20, a light guide plate 101 of the present embodiment arranged along the entire surface of the liquid crystal panel 20, and a light guide plate 10.
1 and the light source 2 arranged along the side surface of the end portion. A reflector 3 whose inner surface is reflective is provided around the light source 2 and reflects light from the light source 2 toward the light guide plate 101.

The light guide plate 101 is made of a transparent material and is arranged in front of the reflective liquid crystal display panel 20 as a so-called front light source (front light). The light source 2 is arranged along the side surface of the light guide plate 101 on the side surface of the end portion of the light guide plate 101 (the upper side of the light guide plate 101 in FIGS. 1 and 2).

The light guide plate 101 has a light emitting surface 111 facing the liquid crystal display panel 20, and a front surface 112 opposite to the light emitting surface 111. As shown in FIG. 2, a large number of sine wave-shaped grooves 114 are formed on the front surface 112 side by side along the longitudinal direction of the light source 2. The pitch of the grooves 114 corresponds to the pixel pitch of the liquid crystal display panel 20. The pitch of the grooves 114 will be described later.

A twill 115 is provided between the grooves 114 adjacent to each other.
The twill 115 also has a sine wave shape like the groove 114. In FIG. 2, only one twill 115 is shown.

As shown in FIG. 1, the groove 114 and the twill 11
The cross-sectional shape of the front surface 112 of the light guide plate 101 in which 5 is formed has a sawtooth shape formed by the inclined surface 116.
The light emitted from the light source 2 and guided through the inside of the light guide plate 101 is efficiently emitted toward the liquid crystal display panel 20 by the groove 114 and the traverse 115.

Part of the light emitted from the light source 2 directly enters the light guide plate 101, and the remaining part of the light is reflected by the reflector 3 and enters the light guide plate 101. In the light guide plate 101,
The incident light is repeatedly reflected between the light emitting surface 111 and the front surface 112, and a part of the light hits the inclined surface 116 to change its direction and is emitted from the light emitting surface 111.

In this way, the light from the light source 2 is emitted from the light emitting surface 114 and illuminates the liquid crystal display panel 20.

As shown in FIG. 1, an antireflection layer 105 may be provided on the light emitting surface 111 of the light guide plate 101. By providing the antireflection layer 105, the total amount of light emitted from the light guide plate 101 can be increased. This antireflection layer 105 allows light whose direction is changed by the inclined surface 116 to emit light.
It has the function of decreasing the proportion of light reflected back to the light guide plate 101 at 11 and consequently increasing the amount of light emitted from the light emitting surface 111. Further, the light emitted from the light emitting surface 111, reflected by the reflecting surface of the liquid crystal display panel 20, and traveling toward the observer 30 is reflected by the light emitting surface 111, and the liquid crystal display panel 20.
It also works to prevent the return to the direction of.

As described above, the liquid crystal display panel 20 is illuminated by the light guide plate 101, and the observer 30 sees the reflected light from the liquid crystal display panel 20 through the light guide plate 101. In addition, actually, a larger number of grooves 114 than those shown in the drawing are formed in the light guide plate 101.

As described above, the light guide plate 101 of the present embodiment.
Then, since the groove 114 is formed in a curved shape instead of a straight shape, it is possible to significantly suppress the moire generated due to the relationship between the position of the pixel and the position of the groove 114.

FIG. 3 shows a groove 114 formed in the light guide plate 101.
It is a figure which shows the pitch of. FIG. 3 is an enlarged view of FIG.

In the present embodiment, the pitch of the grooves 114 is not constant but varies line by line with the pixel pitch of the liquid crystal display panel 20 as a reference. As shown in FIG. 3, the groove 1
14, the pixel pitch is p → p × 1.
Such a cycle is repeated with a fluctuation of 02 → p × 0.98 → p × 1.01 → p × 0.99 as one cycle. Further, as the pitch of the grooves 114 changes, the twill 115
The pitch of is also changing.

Thus, the groove 11 is formed with respect to the pixel pitch p.
4 and twill 115 pitch ± 1% or ±
By varying by 2%, it is possible to further suppress moire generated due to the relationship between the pixel pitch and the shape of the front surface 112 of the light guide plate 101.

Further, in this embodiment, the depth of the groove 114 (the distance H from the bottom of the groove 114 to the top of the twill 115) is set to the groove 1.
By making the pitch constant regardless of the pitch of 14, it is possible to secure the uniformity of brightness without periodically generating a bright line portion and a dark line portion on the display.

In FIG. 3, the pitch of the groove 114 is varied in 5 steps (p, p ± 1%, p ± 2%), but the groove pitch is 4 steps or less, or 6 steps.
You may change by the value more than a step. Further, the fluctuation cycle of the groove may be longer or shorter. Furthermore, the groove may not be changed periodically, but may be changed randomly, for example.

In the above embodiment, the depth of the groove 114 (the groove 1
Groove 11 from the bottom of 14 to the top of the twill 115
Although it is constant regardless of the pitch of 4, the groove may be deepened as the distance from the light source increases.

FIG. 4 schematically shows such a case, and the distance from the bottom of the groove 114A to the top of the twill 115A increases as the distance from the light source increases, that is, as it goes upward in FIG. Note that FIG. 4 shows a case where the light source is arranged below. By increasing the depth of the groove as the distance from the light source increases, the amount of light emitted from the light guide plate can be made uniform over the entire surface of the liquid crystal panel 20.

Also in this case, the depth of the groove 114A (the distance from the bottom of the groove 114A to the top of the twill 115A)
Does not fluctuate in accordance with the pitch of the groove 114A and continuously changes, so that a bright line portion and a dark line portion do not periodically appear on the display.

In the above embodiment, an example in which the light guide plate of the present invention is applied to the front light for illuminating the liquid crystal display panel has been described, but the light guide plate of the present invention can be applied to display panels other than the liquid crystal display panel. Further, the light guide plate of the present invention can be applied to the backlight of the display panel.

The shape of the groove or the twill when the light guide plate is viewed from the front side is not limited to the above embodiment, and various curved shapes can be adopted. For example, as shown in FIG. 5, the groove 214 formed in the light guide plate 201 may have a sawtooth shape. Also in this case, the occurrence of moire can be significantly suppressed as compared with the case where a large number of grooves are arranged in parallel according to the arrangement of pixels. In the present specification, a line formed by combining straight lines is also included in the “curve”.

In the light guide plate of the present invention, the forming direction of the groove is not limited to that in each of the above embodiments. FIG. 6 is a view showing an example in which sine wave-shaped grooves are formed in two directions.
In the example of FIG. 6, the light source 2A is arranged so as to face one side surface of the end portion of the light guide plate 101A and two side surfaces of the end portion one side surface adjacent to the one side surface. In this example, 2 which are orthogonal to each other
A groove 114A is formed along the direction. The light source may be integrated, or may be two separate light sources prepared for each side surface of the light guide plate 101A.

In the above embodiment, an example in which the groove pitch is varied instead of being constant is shown, but the groove pitch may be constant according to the pixel pitch. Even when the pitch of the grooves is constant, moire can be significantly suppressed by forming the grooves in a curved shape.

In the above embodiment, an example in which the light guide plate of the present invention is applied to a front light has been described, but the light guide plate of the present invention can be applied to a so-called backlight arranged on the back side of the display panel. In addition, normally, the moire generated due to the relationship between the shape of the light guide plate and the pixel pitch is more remarkable when the light guide plate is applied to the front light. Therefore, the light guide plate of the present invention is particularly effective when applied to a front light in terms of the effect of reducing moire.

[0038]

According to the light guide plate of the present invention, since the pitch of the grooves or the twill formed in the light guide plate is changed with respect to the pixel pitch of the display panel, moire can be suppressed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a liquid crystal display device including a light guide plate of this embodiment.

FIG. 2 is a front view of the liquid crystal display device as seen from the front direction.

FIG. 3 is a diagram showing pitches of grooves formed in a light guide plate.

FIG. 4 is a diagram showing an example in which the groove is deepened as the distance from the light source increases.

FIG. 5 is a diagram showing a sawtooth groove.

FIG. 6 is a view showing an example in which grooves are formed in two directions.

[Explanation of symbols]

101, 201, 101A Light guide plate 2, 2A Light source 112 Front surface (surface opposite to surface of light guide plate facing display panel) 114, 214, 114A Grooves 115, 215, 115A Twill 20 Liquid crystal display panel (display panel)

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H038 AA55 BA06                 2H091 FA23X FA23Z FA37X FA37Z                       FA42X FA42Z FD06 GA03                       LA16                 5G435 AA01 BB12 BB15 BB16 CC09                       EE22 EE26 FF08

Claims (6)

[Claims] 1. A light guide plate arranged along a front surface or a back surface of a display panel, wherein a plurality of curved grooves or twill are formed on a surface of the light guide plate opposite to a surface facing the display panel. The light guide plate characterized by having. 2. The light guide plate according to claim 1, wherein the grooves or the grooves are formed at a pitch corresponding to a pixel pitch of the display panel. 3. The light guide plate according to claim 1, wherein the groove or the twill is formed in a sine wave shape. 4. The light guide plate according to claim 1, wherein the groove or the twill is formed in a sawtooth shape. 5. The light guide plate according to claim 1, wherein the light guide plate is disposed on a front surface side of the display panel. 6. A light guide plate arranged along a front surface of a display panel, wherein a curved groove or a twill is formed on a surface of the light guide plate opposite to a surface facing the display panel. Characteristic light guide plate.