JP2855101B2 - Liquid crystal display panel backlight system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved structure of a backlight system for a liquid crystal display panel. In particular, the use of the unidirectional reflection structure of the light guide reduces the loss of wasteful energy by directing light rays as much as possible in the viewing direction. Therefore, the utilization rate of light energy is improved, and therefore, the backlight of the liquid crystal display panel is reduced.
The system is improved.

[0002]

FIG. 1 is a partial perspective view of a conventional liquid crystal display panel backlight system S1. The backlight system S1 mainly has a light source section 5 for providing a necessary light source in the backlight, a front face 9 and a rear face 10 which are parallel and flat to each other, and whose end 7 is connected to the light source section 5. An adjacent light guide 3 for receiving light rays emitted from the light source unit 5, a reflection mask 6 surrounding the light source unit 5, and reflecting light emitted from the light source unit 5 so as to enter the light guide 3; A reflection panel 4 for reflecting light rays emitted from the light guide 3 and passing through the back surface 10 so as to return to the light guide 3; and the light provided between the liquid crystal display panel 1 and the light guide 3. A diffusion panel for reducing the non-uniformity of light incident on the liquid crystal display panel by diffusing light emitted from the conductor toward the liquid crystal display panel at an early stage.

As shown in the liquid crystal display panel 1 of FIG. 1, a light beam A radiated from a light source unit 5 and incident on a light guide 3 through an end 7 is shown.
Generally have front 9 and back 10 parallel to each other.
And the light is repeatedly reflected, and advances in a direction away from the light source unit 5. However, when the light beam A hits the scattering material 8, the above-described total reflection is stopped, and a part of the light beam is scattered to the liquid crystal display panel 1. Thereby, the backlight of the liquid crystal display panel 1 is provided. However, many of the scattered light rays are scattered or reflected many times before reaching the liquid crystal display panel 1. Therefore, the more times the light is scattered or reflected, the more energy is lost. From this, there is clearly room for improvement in this conventional backlight system S1.

In view of the shortcomings of the backlight system S1, another improved backlight system S2 was presented in US Pat. No. 5,050,946. FIG.
FIG. 3 and FIG. 4 show the structure of the backlight system S2. FIG. 2 is a partially developed perspective view. FIG.
FIG. 3 is an enlarged side view of a portion III in FIG. 2. FIG.
FIG. 4A is an enlarged perspective view near the inclined surface N in FIG. 3, and FIG. 4B shows a coordinate system used for description.

Referring to FIG. 2 and FIG. Backlight·
The system S2 has a light source unit 5 similar to S1 shown in FIG.
, Reflection mask 6, light guide 13, reflection panel 14
And a diffusion panel 2. As shown in the coordinate system of FIG. 4B, the Z direction indicates the vertical direction of the light guide 13 (that is, the direction away from the light source unit). The Y direction indicates the height direction of the light guide 13. The X direction indicates the longitudinal direction of the lamp tube constituting the light source unit 5, that is, the Y direction
The direction perpendicular to the direction and the Z direction.

Referring to FIGS. 2 and 3, this backlight
When comparing system S2 with backlight system S1, the only difference is the shape of the light guide. In this backlight system S2, the front face 19 of the light guide 13 is also flat, but the back face 20 thereof has a plurality of parallel portions G, E, F,. , And connecting portions M, N,... Forming an angle of about 135 ° with the parallel portions G, E, F,. Each of the parallel parts G, E, F,...
Is the distance in the Y direction between the end 17 and the vertical direction (Z direction).
Gradually decreases as the distance at (ie, away from edge 17) increases (FIG. 3).

As shown in FIGS. 2 and 3, the light emitted from the light source unit 5 is incident on the light guide 13 through the end 17,
The light beam A, which forms a relatively large angle with each other, is parallel to the parallel portions G, E, F,.
The light source unit 5 moves forward in the direction away from the light source unit 5 while undergoing total reflection repeatedly. On the other hand, if the light beam B, which forms a relatively small angle with the front surface 19, enters the inclined connecting portions M, N,..., Total reflection occurs. This totally reflected ray B
Is incident on the front 19 at an angle that is generally less than the critical angle,
Then, the light is directly transmitted through the incident portion to provide a backlight to the liquid crystal display panel 1. Therefore, the design of this backlight system S2 is to reduce the traveling path in the light guide 13 for some light rays, so that the light rays reach the inclined connection immediately after the light rays 13 Through the front face 19 of the light guide 13 and consequently energy loss due to light rays being scattered or reflected many times in the light guide 13 is reduced.

According to the backlight system S2, the disadvantages of the backlight system S1 can be improved to some extent, but there is still something to be improved. For example, when a light beam C that is perpendicular or substantially perpendicular to the connection portion N directly enters the connection portion N, most of the energy of the light beam C is directly transmitted through the incident point and emitted. The transmitted light is reflected back by the reflective panel 14 in an ideal situation. However, in practice, since the reflection efficiency of the reflection panel 14 is not 100% with respect to the back surface, the reflection becomes an arbitrary reflection in the range of the half-angle, and as a result, the energy becomes large by several scatterings or reflections. Partially decreases.

[0009]

In view of the above problems,
SUMMARY OF THE INVENTION It is an object of the present invention to overcome the drawbacks of the conventional backlight system S2 and to reduce the use of light rays at the bottom of the light guide by restricting the light rays entering the connection from being transmitted through the point of incidence. It is an object of the present invention to provide a backlight system for a liquid crystal display panel which improves the efficiency.

[0010]

In order to achieve the above object, a backlight system for a liquid crystal display panel according to the present invention comprises one or a plurality of light source units for providing a light source required for a backlight, and one light source. And a conductor. The light guide receives a light beam emitted from the light source unit and provides a necessary backlight for a liquid crystal display panel. The light guide has a substantially flat front surface facing the liquid crystal display panel, a rear surface opposite to the liquid crystal display panel with respect to the front surface, and a plurality of ends adjacent to each of the one or more light source units. And The front surface extends in a vertical direction away from the light source unit. The back surface includes a plurality of parallel portions that are parallel to the front surface, and a connecting portion that connects both adjacent parallel portions. An interval between each of the plurality of parallel portions and the front surface decreases with an increase in a vertical distance between each of the parallel portions and the end.

A feature of the present invention is that each of the connecting portions on the back surface of the light guide is substantially perpendicular to the longitudinal direction and has a plurality of inclined portions that form a predetermined angle of inclination with each of the connected parallel portions. The surfaces form a continuous roof shape and each adjacent pair of these slopes forms an angle of 60 to 120 degrees with each other. With the above structure, the angle between the normal to the inclined surface and the light beam incident on the inclined surface is increased, and thus the light beam transmitted directly through the inclined surface and emitted to the outside of the light guide is reduced. .

Further, in front of the light guide in the backlight system for the liquid crystal display panel, a plurality of integrated prisms are provided in parallel with the liquid crystal display panel and parallel to each other. With the above structure,
Light rays transmitted through the front of the light guide and emitted to the liquid crystal display panel can be converged in a relatively small viewing angle range.

Further, at the end of the light guide in the backlight system of the liquid crystal display panel, there is a converging portion extending toward the light source and integrally formed. As for the converging portion, the cross-sectional area along the vertical direction becomes smaller as approaching the light source portion 5.

In the backlight system for a liquid crystal display panel, a converging portion is further provided between the end of the light guide and the light source. The converging section has a flat first side facing the light source section and a second side facing the end. The second side is provided with a plurality of rows of prisms parallel to the surface of the end and parallel to each other.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 5 is a partial perspective view of a liquid crystal display panel backlight system S3 according to an embodiment of the present invention. FIG. 5 shows a portion corresponding to the portion shown in FIG. 4A in the backlight system S2 of the conventional liquid crystal display panel shown in FIG. 2 according to this embodiment. That is, it is a structure of a connecting portion that connects the E portion and the F portion that are parallel to each other. The same parts are denoted by the same reference numerals as in FIG. In FIG. 4A, a connecting portion N composed of a single inclined plane is a pair of inclined surfaces which form a predetermined inclination angle with the E portion and the F portion and are substantially orthogonal to each other in FIG. The configuration is based on N1 and N2.
The inclined surfaces N1 and N2 together form a roof-like shape.

Referring to FIG. 4A and FIG. 5, an effect produced by changing the structure of the connecting portion will be described. FIG.
In (A), a ray C that is perpendicular or nearly perpendicular to the slope N and that passes through the back of the light guide loses considerable energy. On the other hand, in FIG. 5, since the angle formed between the same ray C and the normal to the inclined surface N1 increases, when the light beam C first enters the point P1 on the first inclined surface N1, total reflection occurs. Are more likely to occur. Further, when the totally reflected light is incident on the point P2 of the second inclined surface N2, a second total reflection occurs again, and the light is transmitted through the front (not shown) and exits. This light beam can be effectively used as the backlight of the liquid crystal display panel, and the disadvantage that the energy in the conventional backlight system S2 shown in FIG.

FIG. 6 is a perspective view of a light guide 33 in a backlight system S4 for a liquid crystal display panel according to another embodiment of the present invention. In this embodiment, the light guide 33
The structure of the back surface of FIG. 5 includes the inclined surfaces N1 and N2 that are substantially orthogonal to each other and that are between adjacent parallel portions on the back surface shown in FIG.
This is an improvement based on the structure of the connecting portion composed of. That is, the first connecting portion closest to the end 37 of the light guide 33 is taken as an example, and the connecting portion has a series of inclined surfaces N11 arranged in the X direction (see the coordinate system in FIG. 4B). The pairs of N21, N31 and N41, N51 and N61,... Correspond to the pairs of inclined surfaces N1 and N2 shown in FIG. The adjacent inclined surfaces of each pair have a substantially orthogonal relationship to one another. Similarly, the second connecting portion adjacent to the first connecting portion is constituted by a series of inclined surfaces N12 and N22,..., And so on. Thus, the structure of the back surface of the light guide 33 of the embodiment shown in FIG. 6 is formed.

FIG. 7 shows a liquid crystal display panel backlight system S5 according to still another embodiment of the present invention.
2 shows a perspective view of the light guide 43. FIG. The structure of the light guide 43, particularly the structure on the back surface (not shown in detail) is almost the same as the structure shown in FIG. 5 or FIG. In this example,
On its front side, a plurality of rows of prisms 44 parallel to a liquid crystal display panel (not shown) and parallel to each other are further provided.
Are formed integrally with the front surface. With this front structure, light transmitted through the front of the prism 44 and emitted to the liquid crystal display panel can be converged to a relatively small viewing angle range. As described above, the design of the parallel prism 44 having a function of converging light rays has already been proposed in the prior art (for example, US Pat. No. 4,791,540), and thus details thereof will be omitted.

FIG. 8 shows a backlight system S6 for a liquid crystal display panel according to still another embodiment of the present invention.
A perspective view of the light guide 53 and the light source unit 5 is shown. The light guide 5
The structure of No. 3, especially the structure of the back surface (not shown) is almost the same as the structure shown in FIG. 5 or FIG. In this embodiment, at an end 57 of the light guide 53 near the light source unit 5, there is a converging portion 54 extending further toward the light source unit 5 and formed integrally with the end 57. The convergence unit 54 is Z
Along the opposite direction (see the coordinate system of FIG. 4B), the cross-sectional area (area in the XY plane) decreases as approaching the light source unit 5. Such a converging section 54 includes the light guide 5
The light rays incident on 3 are converged. As a result, the light guide 53
The convergence in the Z direction of the light beam emitted from the front of the light emitting device is enhanced. Since the design of the convergence unit 54 is already well known, its details are omitted.

FIGS. 9 and 10 show still another embodiment of the liquid crystal display panel according to the present invention.
A perspective view of a light guide, a light source unit and a converging unit is shown for a system S7 and a backlight system S8. First, the structure of the backlight system S7 shown in FIG. 9 will be described.
In the backlight system S7, the structure of the light guide 63, particularly the structure of the bottom surface (not shown) is substantially the same as the structure shown in FIG. 5 or FIG. In this example, a converging section 64 is further provided between the end 67 of the light guide 63 and the light source section 5. The converging section 64 has a flat first side 66 facing the light source section 5 and a second side 68 facing the end 67. The second side 68 is provided with a plurality of rows of prisms that are parallel to the surface of the end 67 and parallel to each other. These prisms extend substantially parallel to the X direction (see FIG. 4B), and can firstly converge light rays incident on the light guide 63 on the YZ plane.

Next, the structure of the backlight system S8 will be described with reference to FIG. The structure of the backlight system S8 is the same as that of the backlight system S7 shown in FIG.
It is almost the same. That is, the converging section 74 is further provided between the end 77 of the light guide 73 and the light source section 5. The converging section 74 has a flat first side 76 facing the light source section 5 and a second side 78 facing the end 77. Second side 78
Are provided with a plurality of rows of prisms which are parallel to the surface of the end 77 and parallel to each other. However, these prisms extend substantially parallel to the Y direction (see FIG. 4B),
Can be first converged on the XZ plane. The details of the design of the convergence unit 64 and the convergence unit 74 are omitted because they are already well known.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications can be made without departing from the gist of the present invention.
It should be appreciated that these alternatives are within the scope of the invention. For example, in the above-described embodiment, among the connecting portions connecting the two parallel portions on the back surface of the light guide, it has been described that a pair of adjacent inclined surfaces are substantially orthogonal to each other, but the angle formed by the pair of inclined surfaces is 60 to Within the range of 120 degrees, a function similar to that of the above-described embodiment can be achieved.

[Brief description of the drawings]

FIG. 1 is a partial perspective view showing a conventional liquid crystal display panel backlight system S1.

FIG. 2 is a partial perspective view showing another conventional liquid crystal display panel backlight system S2.

FIG. 3 is an enlarged side view of a portion III of the light guide in FIG. 2;
And the situation in which the light rays are advanced or reflected therein.

FIG. 4A is an enlarged perspective view showing the vicinity of a connection portion on the back surface of the light guide in FIG. 3, and FIG. 4B is a diagram showing a coordinate system used for explaining the structure of the back surface of the light guide. FIG.

FIG. 5 is a partial perspective view showing a portion corresponding to FIG. 4A in a backlight system S3 for a liquid crystal display panel according to an embodiment of the present invention.

FIG. 6 is a perspective view showing a light guide in a backlight system S4 for a liquid crystal display panel according to another embodiment of the present invention.

FIG. 7 is a perspective view showing a light guide of a backlight system S5 for a liquid crystal display panel according to yet another embodiment of the present invention.

FIG. 8 is a perspective view showing a light guide and a light source unit in a backlight system S6 for a liquid crystal display panel according to still another embodiment of the present invention.

FIG. 9 is a perspective view showing a light guide, a light source unit and a converging unit in a backlight system S7 of a liquid crystal display panel according to still another embodiment of the present invention.

FIG. 10 shows a liquid crystal display panel backlight system S8 according to still another embodiment of the present invention.
It is a perspective view showing a light source part and a converging part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel 2 Diffusion panel 3 Light guide 4, 14 Reflection panel 5 Light source part 6 Reflection mask 7, 17, 37, 57, 67, 77 End 8 Scattering material 9, 19 Front 10, 20 Back 13, 33, 43, 53, 63, 73 Light guide 44 Square prism 54, 64, 74 Converging part 66, 76 First side 68, 78 Second side

Claims (4)

(57) [Claims] 1. A light source unit or a plurality of light source units for providing a light source, and facing the liquid crystal display panel to provide a necessary backlight of the liquid crystal display panel by receiving a light beam emitted from the light source unit. A substantially flat front extending in the vertical direction away from the light source unit, a plurality of parallel portions parallel to the front surface and opposite to the liquid crystal display panel with respect to the front surface, and both adjacent parallel portions. A light guide having a back surface including a connecting portion to be connected and one or more ends adjacent to each of the one or more light source portions, and a light guide between each of the plurality of parallel portions and the front surface The spacing decreases with an increase in the vertical distance between each of the parallel portions and the writing end, and each of the connecting portions on the back surface of the light guide is substantially perpendicular to the vertical direction. , Each of the two connected flats A continuous roof shape is formed by a plurality of inclined surfaces forming a predetermined inclination angle with the row portion, and each pair of adjacent inclined surfaces forms an angle of 60 to 120 degrees with each other, A liquid crystal characterized by increasing an angle between a surface normal and a light beam incident on the inclined surface, and thereby reducing a light beam transmitted directly through the inclined surface and emitted to the outside of the light guide. Display panel backlight system. 2. A plurality of integrally formed prisms parallel to the liquid crystal display panel and parallel to each other are provided on the front surface of the light guide. 2. The backlight system for a liquid crystal display panel according to claim 1, wherein light rays transmitted through the front surface and emitted to the liquid crystal display panel can be converged in a relatively small viewing angle range. 3. A converging portion extending toward the light source portion and integrally formed is provided at the end of the light guide, and a cross-sectional area of the converging portion in the vertical direction approaches the light source portion. 2. The backlight system for a liquid crystal display panel according to claim 1, wherein the size of the backlight decreases. 4. A converging section is further provided between the end of the light guide and the light source section, and the converging section is opposed to the flat first side facing the light source section and the end. 2. The method according to claim 1, wherein the second side is provided with a plurality of rows of prisms that are parallel to the surface of the end and parallel to each other. Liquid crystal display panel backlight system.