JPH07325303A - Back light for liquid crystal panel - Google Patents

Abstract

PURPOSE:To efficiently and homogeneously irradiate a liquid crystal panel with light without using a light transmission plate by diffusing only light transmitted through a partial transmission mirror of directly projected, reflected and scattered light and irradiating the liquid crystal panel with the light. CONSTITUTION:A light source 12 is arranged in a main body provided with a diffuse reflecting surface 14b at the inside surface. The partial transmission mirror 18 capable of partially transmitting light is arranged at an opening 14a. As for the partial transmission mirror 18, a transmission port 18b near the light source is made narrower in width so that the transmissivity at the part near the light source 12 may be lower than the transmissivity at the part far from the light source 12, and also, the transmission port 18b far from the light source 12 is made larger in width. Only the light made incident on the transmission port 18b out of the light projected to the partial transmission mirror 18 is transmitted through the partial transmission mirror 18, and the light reflected by a mirror surface 18a is returned to the diffuse reflecting surface 14b. By installing a diffusing plate 20 on the light-emitting surface side of the partial transmission mirror 18, a shade generated by the mirror surface 18a is eliminated due to the transmission of the light through the part concerned by diffusion, so that the occurrence of the shade on the surface of the back light is surely prevented in addition to the uniformization of the light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight for a liquid crystal panel, which irradiates the back surface of the liquid crystal panel with light from a linear light source to secure the brightness of the display surface of the liquid crystal panel.

[0002]

2. Description of the Related Art For example, a liquid crystal panel has been widely used in recent years as a display for a notebook type or laptop type personal computer (personal computer), a word processor (word processor), a portable television and the like.

In general, since the liquid crystal panel does not emit light itself, it is constructed so as to obtain appropriate brightness, that is, brightness, on the display surface of the liquid crystal panel in combination with auxiliary lighting called a backlight installed on the back surface. ing.

As shown in FIG. 9, such a backlight 210 is generally a light guide plate capable of propagating light from linear light sources 212 arranged at opposite ends to a distant portion, that is, a central portion. It has 213. The light guide plate 213 is formed of, for example, a transparent acrylic plate and has a lower surface in the figure,
A dot pattern 213a that diffusely reflects light is provided by printing or the like.

Then, a diffusion plate (prism plate) 213b having a light diffusion effect is provided on the upper surface of the light guide plate 213, which is a light emitting surface, in the figure.
Etc. are arranged and diffused by diffuse reflection at the dot pattern 213a of the light guide plate, and further diffused and transmitted the light from the light source, which is spectrally separated, by the diffuser plate on the upper surface, so that more uniform light can be obtained over the entire irradiation surface. In addition, the backlight 210 is constructed.

[0006]

However, since a light guide plate made of an acrylic plate or the like is generally heavy and needs a thickness sufficient to propagate light, it is possible to avoid weighting a known backlight having a light guide plate. I can't.

Since the light from the light source is propagated through the light guide plate, it tends to be attenuated during the propagation. That is,
In order to make the liquid crystal panel brighter, the output of the light source must be sufficiently increased in advance in consideration of the light attenuation rate and the like. Therefore, it is not easy to reduce the power consumption of the backlight, which has been recently demanded.

From the above, it is generally considered to remove the light guide plate from the backlight. However, homogenization of light cannot be easily achieved under the simple reflection and diffusion of light in a box-shaped main body in which a light source is arranged. Especially in simple reflection and diffusion of light,
Since the direct light from the light source cannot be sufficiently suppressed, a difference in brightness is likely to occur in a portion near the light source and a portion far from the light source.

Here, for example, a partially transmissive light shielding plate called a lighting curtain that allows a part of light to pass therethrough,
There is also known a configuration in which direct light in a portion close to a light source is suppressed and light transmitted through a lighting curtain is further diffused by a diffusion plate.

However, since the light shielded by the lighting curtain is easily absorbed by the lighting curtain,
The reduction of light propagation efficiency and irradiation efficiency is inevitable.

An object of the present invention is to provide a backlight for a liquid crystal panel which can efficiently and uniformly illuminate the liquid crystal panel without using a light guide plate.

[0012]

In order to achieve this object, according to the present invention, a single or a plurality of parts are provided at a predetermined position in a box-shaped main body having an inner surface as a diffuse reflection surface for diffusing light by diffuse reflection. A light source is provided. Then, a part of the light can be transmitted and the transmittance of the part near the light source is made lower than that of the part far from the light source, and a diffuser plate that allows incident light to pass through while being diffused in multiple directions. And are placed so as to overlap the opening of the main body.

[0013]

According to this structure, the light directly transmitted from the light source and / or the light that is transmitted through the partial transmission mirror among at least one of the light reflected and scattered by the mirror surface of the partial transmission mirror and the diffuse reflection surface in the main body. Since only the light is diffused by the diffusing plate to irradiate the liquid crystal panel, uniform brightness can be secured on the entire irradiation surface without using the light guide plate.

[0014]

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

As shown in FIG. 1, in a liquid crystal panel backlight 10 according to the present invention, a linear light source 12 is arranged inside a box-shaped main body 14.

The backlight 10 is usually formed so that the liquid crystal panel can be illuminated from the back side as an auxiliary illumination for giving appropriate brightness (brightness) to a liquid crystal panel (not shown) for displaying characters and the like. The combination of the liquid crystal panel and the backlight 10 constitutes a display such as a notebook-type or laptop-type personal computer (personal computer), a word processor (word processor), and a portable TV having appropriate brightness on the display surface. .

Since the structure of the liquid crystal panel is publicly known and the structure itself is not the gist of the present invention, a detailed description of the liquid crystal panel is omitted here.

As can be seen from FIG. 2 in addition to FIG.
The main body 14 is formed, for example, in the shape of a box having a partial opening 14a on the upper surface in the figure, and the inner surface 14b is formed as a diffuse reflection surface that diffuses light in multiple directions by irregular reflection. The diffuse reflection surface (inner surface) 14b of the main body is formed by, for example, embossing unevenness or high-concentration special ink.
It is surface-treated so that it can diffusely reflect light.

The linear light sources 12 are provided in the internal space of the main body 14 which is an air layer, for example, at two positions at opposite ends of the main body so as to be separated from each other.

In such a structure, the light from the light source 12 is scattered by the diffuse reflection surface 14b of the main body, and the light is emitted from the opening of the main body.
It is irradiated indirectly in the direction of 14a.

As the light source 12, for example, a non-directional cold cathode tube can be used. However, as a cold cathode tube,
A well-known commercially available product can be used, and the configuration itself is not the purpose of the present invention, and therefore will not be described in detail here.

Here, as shown in FIG. 1, the side portion (opposing end portion) of the main body 14 in which the light source 12 is disposed is shaped so as to prevent an excessive amount of direct light from entering in the light irradiation direction. , For example,
It is formed in a shape having a cover 14c such as a reflector in the irradiation direction. In the exemplary embodiment, cover 14 is provided as part of body 14.
By forming c and making the inner surface of the cover a diffuse reflection surface similar to other surfaces, light is focused in the central direction of the main body.

As shown in FIGS. 1 and 2, in the present invention, for example, a partial transmission mirror 18 which allows a part of light to pass therethrough is arranged in the opening 14a of the main body. Figure 1
In addition, as can be seen from FIG. 3, as the partial transmission mirror 18, for example, a slit mirror (striped mirror) in which a mirror surface 18a that reflects light and a slit-shaped transmission opening 18b that transmits light are alternately arranged. (Also called) can be used.

As can be seen from FIG. 3, the partial transmission mirror 18 has a width of the transmission port 18b near the light source so that the transmittance of the portion near the light source 12 is lower than that of the portion far from the light source 12. Is narrowed and the width of the transmission port near the center, that is, near the center, is widened. Since such a partial transmission mirror 18 has an effect of suppressing the transmission of light in a portion close to the light source 12 and bringing the light to a portion far from the light source, the amount of light emitted from the partial transmission mirror, that is, the transmission. Bias in quantity is sufficiently suppressed.

At this time, the light which does not pass through the transmission opening 18b of the partial transmission mirror, that is, the light which is irradiated on the mirror surface 18a is incident on the diffuse reflection surface 14b of the main body by the reflection on the mirror surface. The light incident on the diffuse reflection surface 14b from the mirror surface 18a of the partial transmission mirror is diffused while being diffusely reflected together with the light directly incident from the light source 12, and is irradiated again in the direction of the partial transmission mirror.

Of the light emitted to the partial transmission mirror 18, only the light incident on the transmission port 18b passes through the partial transmission mirror, and the light reflected on the mirror surface 18a is further returned to the diffuse reflection plate. Be done. By repeating this operation, the light from the light source 12 is applied to the entire surface of the partial transmission mirror 18.

Here, when the light from the light source 12 passes through the partial transmission mirror 18, the generation of a shadow due to the mirror surface 18a of the partial transmission mirror is inevitable. Therefore, as shown in FIGS. 1 and 2, in the present invention, for example, a diffusing plate 20 that allows the light (transmitted light) from the partial transmission mirror 18 to diffuse while appropriately diffusing in multiple directions.
However, it is provided on the emission surface of the partial transmission mirror, that is, on the upper surface in the figure.

As the diffusion plate 20, for example, a prism sheet can be used. The prism sheet is known,
The structure itself is not the purpose of the present invention, and will not be described in detail.

By providing such a diffusing plate 20 on the emission surface side of the partial transmission mirror 18, the shadow generated by the mirror surface 18a is canceled by the diffusion of the light to the relevant portion, so that the light Emitting surface 20a of the diffuser in addition to homogenization
That is, it is possible to reliably prevent the generation of a shadow on the surface of the backlight.

Here, the degree of light diffusion required of the diffusion plate 20 is, for example, the diameter of the light source 12, the light source and the partial transmission mirror 18.
And the relative relationship such as the width of the mirror surface 18a of the partial transmission mirror. In the embodiment, as shown in FIGS. 1 and 2, it is possible to cancel the shadow generated by the mirror surface 18a of the partial transmission mirror by arranging the two diffusion plates 20 (20-1, 20-2) in an overlapping manner. The light is diffused to a certain degree.

The distribution curve of the surface luminance of the backlight 10 of the liquid crystal panel having the above-described structure is shown by the solid line in FIG. As can be seen by comparing with the distribution curve of brightness (dashed line) by direct light from the light source without using a partial transmission mirror, a diffuser plate, etc., according to the transmitted light in the backlight 10 of the present invention, the surface brightness is Almost homogenized over the entire exit surface 20a of the diffuser plate which is the surface. That is, according to the backlight 10 of the present invention, it can be easily understood that substantially uniform light can be irradiated to the entire surface of the liquid crystal panel without using the light guide plate.

Therefore, the backlight 10 of the liquid crystal panel is
Since it can be configured without using a light guide plate, the backlight can be sufficiently reduced in size and weight.

In particular, since the light guide plate, which has been an obstacle to increasing the size of the backlight itself, can be eliminated, the backlight 10 for a large-sized liquid crystal panel can be provided without significantly increasing the weight.

In contrast to the known structure in which the light transmittance of the portion near the light source is suppressed by the shading by the lighting curtain, in the present invention, the mirror surface 18 of the partial transmission mirror is used.
By reflection at a, light other than transmitted light is repeatedly reflected in the direction of the diffuse reflection surface of the main body 14, so that the light is not absorbed by the mirror surface serving as the light shielding surface, and the light propagation efficiency is surely improved. . That is, without using the high-output light source 12,
Since relatively high brightness can be secured on the backlight surface,
The power consumption of the light source can be sufficiently reduced.

The light source 12 is not limited to the illustrated structure in which one light source 12 is provided on each side portion of the main body 14. For example, since it is sufficient for both light sources 12 on the side of the main body to have the same output,
The same number of cold cathode tubes or more may be provided on each side of the main body. The number of the light sources 12 is usually adjusted according to the brightness required in the liquid crystal panel.

Further, in the embodiment, two diffusion plates 20 are used. However, if it is possible to sufficiently eliminate the shadow generated by the mirror surface 18a of the partial transmission mirror and homogenize the brightness on the backlight surface, only one diffusion plate may be used.

Furthermore, if three or more diffuser plates 20 are used, shadows can be erased and brightness can be made more uniform. However, normally, these effects can be sufficiently obtained by providing two diffusion plates 20.

In the embodiment, the partial transmission mirror 18,
Although the diffuser plates 20 (20-1, 20-2) are arranged so as to overlap with each other, this does not mean the close contact state between them. For example, the gap derived from the correlation between the width of the mirror surface 18a of the partial transmission mirror, the diameter of the light source, the distance from the light source to the partial transmission mirror 18, etc. should be set to the partial transmission mirror and the diffusion plate 20 (20-1, 20-2). ), It is possible to obtain a further diffusion effect, so
Elimination of shadows and homogenization of brightness can be easily ensured without impairing the light propagation efficiency. In the embodiment, the backlight 10 is formed for a 21-inch liquid crystal panel,
In this case, the gap between the partial transmission mirror 18 and the diffusion plate 20 (20-1, 20-2) is set to about 7 mm.

Further, in the embodiment, the two diffusion plates 20 (20-1, 20-2) are continuously arranged on the emission surface side of the partial transmission mirror 18, but the invention is not limited to this. , For example, FIG.
As shown in FIG. 5, a partial transmission mirror may be interposed between the two diffusion plates.

In such a structure, the diffuse reflection surface 14 of the main body is
After the light from b is once diffused by the diffusion plate 20-1,
A diffuser plate that is transmitted through the partial transmission mirror 18 and is on the output surface side.
It is diffused again at 20-2 and emitted to the surface. That is, even in such a configuration, reflection of a part of light by the partial transmission mirror 18, adjustment of the amount of light transmission according to the distance from the light source 12, and the diffusion plate 20 (20-1, 20- Since the light is diffused in the same manner as in 2), the same effect as that of the above configuration can be surely obtained.

Although a cold cathode tube is illustrated as the light source 12, it is sufficient if it has a structure capable of emitting light in a linear shape.
Other hot cathode tubes, cold cathode tubes, etc. may be used as the light source. However, since the cold cathode tube is superior to other cathode tubes in terms of heat and life, it is preferable to use the cold cathode tube as a light source.

Further, in the embodiment, the diffusion plate 20 (20-1, 20-2)
Although the prism sheet is illustrated as the above, the diffuser plate is not limited to the prism sheet, as long as it diffuses incident light while transmitting it.

Further, the partial transmission mirror 18 is exemplified as a slit mirror having a slit-shaped transmission opening 18b, but it is not limited to the slit mirror because it is sufficient if it can transmit a part of light, and for example, The partial transmission mirror may be formed from a so-called dot mirror having innumerable dot-shaped transmission openings or mirror surfaces.

Here, in the embodiment, the light source is provided on the side portion of the main body 14.
Although a so-called sidelight type configuration in which twelve are arranged has been illustrated and described, the present invention is not limited to this and, for example, FIG.
The backlight 110 of the liquid crystal panel may be configured as a so-called direct type in which the light source 112 is disposed below the opening 14a as shown in FIG.

In such a configuration, a plurality of light sources
112 are juxtaposed inside the body 14 with equal spacing. The inner surface 14b of the main body is formed as a diffuse reflection surface, and is configured to diffuse the light from the light source 112 under diffuse reflection.

Then, as in the above embodiment, the opening of the main body
The partial transmission mirror 118 and the diffusing plate 20 (20-1, 20-2) are stacked on the 14a, and the direct light from the light source 112 and the diffuse reflection surface 14b are reflected from the mirror surface 118a and the transmission opening 118b of the partial transmission mirror. The backlight 110 of the liquid crystal panel is configured to reflect or transmit the indirect light of the above and to diffuse the transmitted light from the transmission port of the partial transmission mirror by the diffusion plate.

Here, such a direct type backlight
Also in the partial transmission mirror 118 of 110, the light transmittance is adjusted by the width of the transmission opening 118b. As shown in FIG. 7, also in this configuration, as in the above-described embodiment, the width of the transmission port 118b near the light source 112 is narrowed, and the transmittance of the portion near the light source is set lower than that of the far portion. There is.

The distribution curve of the surface luminance in the backlight 110 of the liquid crystal panel having such a structure is shown by the solid line in FIG. As can be seen by comparing with the brightness distribution curve (broken line) of direct light from the light source without using a partial transmission mirror, a diffuser plate, etc., even in this direct type backlight 110, the surface brightness is equal to that of the illuminated surface of the backlight. Almost homogenized over the entire surface. In other words, also in the direct type backlight 110, the inner surface 14b of the main body is a diffuse reflection surface, and
Insert the partial transmission mirror 118 and the diffuser plate 20 (20-1, 20-2) into the opening 14
By providing in a, it becomes possible to irradiate almost the uniform light to the entire surface of the liquid crystal panel.

Therefore, even in the direct type backlight 110, the same effect as that of the sidelight type of the above-described embodiment can be sufficiently ensured.

Then, such a direct type backlight
In 110, a large number of light sources 112 can be arranged side by side in the main body, and since the light sources are close to the irradiation surface, the intensity of light from the light source, that is, high brightness on the irradiation surface can be obtained. Therefore, the direct type backlight 110 is
It can be used more effectively for a color liquid crystal panel that requires high brightness.

Although FIG. 6 shows an example in which the light sources 112 are arranged at six places, the number of light sources is not limited to this. For example, in a 21-inch color liquid crystal panel, light sources are arranged at 12 places separated by equal intervals. Further, the light source 112 is not limited to a plurality of locations, and for example, the light source may be arranged at one location in the center.

The above-mentioned embodiments are for explaining the present invention and do not limit the present invention in any way.
It goes without saying that the present invention includes all those which are modified or modified within the technical scope of the present invention.

[0053]

As described above, according to the backlight of the liquid crystal panel of the present invention, since the light guide plate is not required,
The backlight can be made smaller and lighter.

Since the light other than the transmitted light is repeatedly reflected in the direction of the diffuse reflection surface of the main body by the reflection on the mirror surface of the partially transmissive mirror, the absorption of the light on the mirror surface serving as the light shielding surface can be sufficiently suppressed. Therefore, the propagation efficiency of the light from the light source is surely improved, and the relatively high brightness is ensured by the low-output light source, so that the power consumption of the light source can be sufficiently reduced.

If a plurality of light sources are arranged below the opening, high brightness can be obtained on the irradiation surface. Therefore, such a structure can be applied to a color liquid crystal panel requiring high brightness.
It can be used more effectively.

Since the effect of diffusing light is sufficiently increased by increasing the number of diffusing plates, by disposing a plurality of diffusing plates, it is possible to diffuse the light according to the output of the light source, the distance from the light source, etc. You can adjust the degree.

Further, a slit mirror as a partial transmission mirror,
If any of the dot mirrors is used, reflection and transmission of light from the light source can be accurately obtained, so that a backlight for a liquid crystal panel having high light propagation efficiency can be easily obtained.

Further, if a gap derived from the correlation between the width of the mirror surface of the partial transmission mirror, the diameter of the light source, the distance from the light source to the partial transmission mirror, etc. is provided between the partial transmission mirror and the diffusion plate, it is even more effective. Since the diffusion effect of is surely obtained, it is possible to easily secure the elimination of shadows and the homogenization of brightness without impairing the light propagation efficiency.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a backlight of a liquid crystal panel according to the present invention.

FIG. 2 is a schematic exploded perspective view of a backlight of a liquid crystal panel.

FIG. 3 is a schematic perspective view of a partially cutaway partial transmission mirror.

FIG. 4 is a distribution diagram showing distribution curves of surface luminance in transmitted light and direct light.

FIG. 5 is a schematic exploded perspective view of a backlight of a liquid crystal panel in a modified example of the present invention.

FIG. 6 is a schematic vertical sectional view of a backlight of a liquid crystal panel according to another modification of the present invention.

FIG. 7 is a schematic perspective view of a partially cutaway partial transmission mirror in the modification of FIG.

FIG. 8 is a distribution diagram showing distribution curves of surface luminance in transmitted light and direct light in the modification of FIG.

FIG. 9 is a schematic vertical sectional view of a known backlight of a liquid crystal panel.

[Explanation of symbols]

 10, 110 LCD panel backlight 12, 112 Light source 14 Main body 14a Opening 14b Diffuse reflection surface (inner surface) 18, 118 Partial transmission mirror 18a, 118a Partial transmission mirror surface 18b, 118b Partial transmission mirror transmission port 20 (20- 1, 20-2) Diffuser 20a Diffuser's exit surface (backlight surface)

Claims (11)

[Claims] 1. In a backlight of a liquid crystal panel, which irradiates light from a linear light source to the back surface of the liquid crystal panel to secure the brightness of the display surface of the liquid crystal panel, diffuse reflection that diffuses light in multiple directions by diffuse reflection. A single or multiple light sources are installed at a predetermined location in a box-shaped body with the inner surface as the inner surface, and part of the light can be transmitted. A lowered partial transmission mirror; a diffuser plate that transmits incident light while diffusing in multiple directions;
Is placed over the opening of the main body and transmitted through the partial transmission mirror from at least one of the direct light from the light source, the mirror surface of the partial transmission mirror, and the light reflected or scattered by the diffuse reflection surface in the main body. A backlight for a liquid crystal panel, which is capable of irradiating a liquid crystal panel by diffusing only light with a diffusion plate. 2. In a backlight of a liquid crystal panel, which irradiates light from a linear light source on the back surface of the liquid crystal panel to secure the brightness of the display surface of the liquid crystal panel, diffuse reflection that diffuses light in multiple directions by diffuse reflection. The same amount of one or more light sources are installed on opposite side ends of the box-shaped body with the inner surface as the inner surface, and part of the light can be transmitted. Partial-transmission mirror that has a lower height than the far part; and a diffuser plate that allows incident light to be transmitted while being diffused in multiple directions;
Is placed over the opening of the main body, and of the light reflected and scattered by the mirror surface of the partial transmission mirror and the diffuse reflection surface inside the main body, only the light that has passed through the partial transmission mirror is diffused by the diffusion plate to the liquid crystal panel. A backlight for a liquid crystal panel, which can be illuminated. 3. A backlight of a liquid crystal panel, which secures the brightness of the display surface of a liquid crystal panel by irradiating the back surface of the liquid crystal panel with light from a linear light source, and diffuse reflection that diffuses light in multiple directions by diffuse reflection. Below the opening of the box-shaped body with the inner surface, a plurality of light sources are arranged with equal spacing, and a part of the light can pass through. A partially transmissive mirror which is made relatively low; a diffuser plate which transmits incident light while being diffused in multiple directions;
Is placed over the opening of the main body and transmitted through the partial transmission mirror from at least one of the direct light from the light source, the mirror surface of the partial transmission mirror, and the light reflected or scattered by the diffuse reflection surface in the main body. A backlight for a liquid crystal panel, which is capable of irradiating a liquid crystal panel by diffusing only light with a diffusion plate. 4. The backlight for a liquid crystal panel according to claim 1, wherein a plurality of diffusion plates that are successively stacked are arranged adjacent to the partial mirror body on the side opposite to the light source. 5. The backlight of a liquid crystal panel according to claim 1, wherein a partial mirror body is interposed between any one of the plurality of diffuser plates. 6. The partially transmissive mirror is a slit mirror formed by a slit-shaped transmissive aperture so that a part of the light can be transmitted, and the light transmissivity is changed depending on the width of the transmissive aperture. 6. A backlight for a liquid crystal panel according to any one of 1 to 5. 7. The partially transmissive mirror is a dot mirror formed so that a part of light can be transmitted by either a mirror surface made up of innumerable dots or a transmissive aperture, and the transmissivity of light depends on the size of the dot. The backlight of the liquid crystal panel according to claim 1, which is changed. 8. In a backlight of a liquid crystal panel, which irradiates light from a linear light source on the back surface of the liquid crystal panel to secure the brightness of the display surface of the liquid crystal panel, diffuse reflection that diffuses light in multiple directions by diffuse reflection. A light source or a plurality of light sources is arranged at a predetermined location in a box-shaped body having an inner surface, and part of the light can pass through. Compare the transmittance of the part near the light source to the part far from it. And a plurality of diffuser plates that transmit the incident light while being diffused in multiple directions; they are continuously stacked on the light source side and placed in the opening of the main body. Liquid crystal panel that diffuses only the light that has passed through the partial transmissive mirror among at least one of the direct light emitted from the mirror, the mirror surface of the partial transmissive mirror, and the light reflected or scattered by the diffuse reflection surface in the main body. It is possible to irradiate LCD panel backlight to be considered. 9. In a backlight of a liquid crystal panel, which irradiates light from a linear light source on the back surface of the liquid crystal panel to secure the brightness of the display surface of the liquid crystal panel, diffuse reflection that diffuses light in multiple directions by diffuse reflection. A light source or a plurality of light sources is arranged at a predetermined location in a box-shaped body having an inner surface, and part of the light can pass through. Compare the transmittance of the part near the light source to the part far from it. And a plurality of diffuser plates that transmit the incident light while being diffused in multiple directions; , Which is placed in the opening of the main body, only the light that has passed through the partial transmissive mirror among the direct light from the light source, the mirror surface of the partial transmissive mirror, and the light reflected or scattered by the diffuse reflection surface in the main body LCD panel by diffusing the A backlight of a liquid crystal panel, which is capable of irradiating the liquid crystal. 10. The backlight for a liquid crystal panel according to claim 1, wherein the partial transmission mirror and the diffusion plate are overlapped with each other with a gap left therebetween. 11. The partially transmissive mirror and the diffuser plate are overlapped with each other, leaving at least a gap derived from the correlation between the mirror surface width of the partially transmissive mirror, the diameter of the light source, and the distance from the light source to the partially transmissive mirror. A backlight for a liquid crystal panel according to any one of claims 1 to 9.