JPH09159835A - Back light device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To greatly reduce the power consumption by making it possible to project light with sufficient brightness even unless a light source lamp is always turned on. SOLUTION: On the reverse surface of a light guide plate 22 which guides the light from the light source lamp 21, many dotted light accumulation films 25a which accumulate and emit light are arrayed at fine intervals, and the light from the light source lamp 21 is accumulated in the dotted light accumulation films 25a. Light emitted by those dotted light accumulation films 25a is projected on a liquid crystal display panel 10 through the light guide plate 22 and a diffusion plate 27 provided on its surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight device such as a liquid crystal display module.

[0002]

2. Description of the Related Art For example, a liquid crystal display module used for an electronic device such as a mobile phone, a mobile call receiver (pager), an electronic notebook, a small television receiver, a notebook personal computer, etc. is mounted on the back side of a liquid crystal display panel. A backlight device is arranged and configured.

The backlight device is classified into a side light type and a direct type.
The sidelight type backlight device is generally a light guide plate that guides the incident light from the end face in the surface direction and emits the light to the front face side, and a light source lamp arranged to face the end face of the light guide plate. A light diffusing plate provided on the surface of the light guide plate for diffusing the light emitted from the light guide plate. The light generated by the light source lamp is incident on the light guide plate, and the light guided inside the light guide plate is The reflection surface formed on the back surface of the light guide plate reflects it to the front surface side of the light guide plate, and the light emitted from the light guide plate is diffused by the diffusion plate and emitted.

Further, the direct type backlight device generally comprises a diffusion plate for diffusing light and a light source lamp arranged on the back side of the diffusion plate, and the light from the light source lamp is diffused by the diffusion plate. Diffuse and emit.

[0005]

However, the conventional backlight device has a problem that power consumption is heavy because the light source lamp is always turned on during its use. This problem is particularly important in portable electronic devices that use a battery as a power source. In portable electronic devices, the battery will be consumed in a short period of time due to power consumption in the backlight device. I had to do it often.

Some liquid crystal display modules for portable electronic equipment use a liquid crystal display panel having both a transmissive display type and a reflective type display function. When bright ambient light (natural light or indoor illumination light) is obtained, it is possible to perform reflection-type display utilizing the ambient light without using a backlight device, but sufficient ambient light is obtained. Since the backlight device has to be used when it is not present, the power consumption of the backlight device has a great influence on the battery life.

It is an object of the present invention to provide a backlight device capable of continuously emitting light of sufficient brightness even when the light source lamp is not always turned on, and having a significantly reduced power consumption. It is what

[0008]

A backlight device of the present invention comprises a light source lamp and a light storing means in which a large number of dot-like light storing films which store and emit light are arranged at a minute pitch,
Light from the light source lamp is stored in each dot-shaped light-storing film that constitutes the light-storing means, and after the light source lamp is turned off, the light emitted by each dot-shaped light-storing film is emitted as illumination light. It is a thing.

That is, this backlight device is configured to emit high-intensity light for a long time by utilizing a light-storing film, and the dot-shaped light-storing film is configured to emit light supplied to the light-storing film. The light is stored and emits high-intensity light above that level, and the light emission is continued for a long time even after the supply of light is cut off.

Therefore, according to this backlight device, it is possible to continuously emit light of sufficient brightness without constantly turning on the light source lamp, so that the power consumption is greatly reduced. be able to.

In the backlight device of the present invention, the dot-shaped light-storing films are arranged at a constant pitch, and the dot-shaped light-storing films are formed to be smaller as the intensity of light incident on each dot-shaped light-storing film increases. Desirably, in this way, even if the intensity of the incident light to each of the dot-shaped light-storing film is different and accordingly the emission brightness of each dot-shaped light-storing film is different, the film of these dot-shaped light-storing film It is possible to make the amount of light emission substantially the same and to make the luminance distribution of the emitted light substantially uniform.

When the present invention is applied to a sidelight type backlight device, the light source lamp faces the end surface of the light guide plate which guides the incident light from the end surface in the surface direction and emits the light to the surface side. And arrange it, and the phosphorescent means,
A dot-shaped light-storing film is formed on either one of the front and back surfaces of the light guide plate, and on the front surface side of the light guide plate, a diffusion plate for diffusing light emitted to the surface of the light guide plate is provided. The light guided through the light guide plate can be stored in the dot-shaped light storing film, and the light emitted from the dot-shaped light storing film can be diffused by the diffusion plate to emit light having a gentle luminance distribution.

In this case, the dot-shaped light-storing film is formed on the back surface of the light guide plate, and the light reflected on the light-storing film surface out of the light guided through the light guide plate and incident on the dot-shaped light-storing film is guided. If the light is emitted to the surface side of the light plate, the light from the light source lamp can be emitted while the dot-shaped light accumulation film is being accumulated while the light source lamp is lit.

When the dot-shaped light-storing films are formed on the back surface of the light guide plate, the dot-shaped light-storing films are arranged at a constant pitch, and the dot-shaped light-storing films are incident on the dot-shaped light-storing films. The larger the strength of, the smaller it is formed.
On the back surface of the light guide plate, a plurality of dot-shaped reflective films that reflect the light guided in the light guide plate to the front surface side of the light guide plate are provided at a constant pitch in correspondence with the portions between the dot-shaped light storage films. If these dot-shaped reflective films are made smaller as the intensity of the light incident on each dot-shaped reflective film becomes smaller, the reflection of the entire dot-shaped luminous film when the light source lamp is turned on is provided. Even if there is a difference in the amount of light, the difference can be compensated by the amount of reflected light in the entire film of each dot-shaped light-storing film, and the luminance distribution of the emitted light when the light source lamp is turned on can be made substantially uniform. .

When the present invention is applied to a direct type backlight device, the light source lamp is arranged on the back surface side of the diffuser plate for diffusing light, and the light storing means is provided on the back surface of the diffuser plate in the form of a dot-shaped light storing film. If it is configured to form, the light from the light source lamp is stored in the dot-shaped light-storing film, the light emitted by the dot-shaped light-storing film is diffused by the diffusion plate, and the light having a gentle brightness distribution is emitted. be able to. Again,
While arranging the dot-shaped luminous film at a constant pitch,
If these dot-shaped light-storing films are made smaller as the intensity of the light incident on each dot-shaped light-storing film becomes smaller, the luminance distribution of the emitted light can be made substantially uniform.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment in which the present invention is applied to a backlight device of a liquid crystal display module will be described below with reference to the drawings. 1 to 3 show a first embodiment of the present invention, and FIG. 1 is a sectional view of a liquid crystal display module provided with a backlight device. The liquid crystal display module is used in electronic devices such as mobile phones, mobile call receivers (pagers), electronic organizers, small television receivers, and notebook personal computers.

First, the structure of the liquid crystal display module will be described. As shown in FIG. 1, the liquid crystal display module has a case 1 in which a liquid crystal display panel 10 and a backlight device 20 are housed.

The case 1 is in the form of a thin box consisting of a front case 1a and a back case 1b.
A display window 2 is opened on the surface of a, and the liquid crystal display panel 10 is arranged so as to face the display window 2.

The liquid crystal display panel 10 has a semi-transmissive reflection plate (half mirror) 13 on the back surface thereof and has both a transmission type and a reflection type display function, and has an external light of sufficient brightness ( When natural light or indoor illumination light) is obtained, external light incident from the front side is reflected by the semi-transmissive reflection plate 13 for display. When external light of sufficient brightness is not obtained, the backlight device 20 is used. It is displayed using the light from.

This liquid crystal display panel is one in which a liquid crystal is sandwiched between a pair of transparent substrates 11 and 12 made of glass or the like, and transparent electrodes for applying an electric field to the liquid crystal are respectively provided on the inner surfaces of the substrates 11 and 12. And an alignment film for aligning liquid crystal molecules in a predetermined alignment state.
Polarizing plates (not shown) are respectively arranged on the outer surfaces of 1 and 12 with their transmission axes or absorption axes oriented in a predetermined direction, and the semi-transmissive reflection plate 13 is provided on the outer surface of the back side polarizing plate. Has been. The liquid crystal display panel 10 is of an active matrix type, a simple matrix type, or a segment display type.

Next, the structure of the backlight device 20 will be described. This backlight device 20 is as shown in FIG.
The light source lamp 21 and the light storage means 25 in which a large number of dot-shaped light storage films 25a are arranged at a minute pitch are provided.

The backlight device 20 of this embodiment is of a side light type, and the light source lamp 21 guides the incident light from the end face in the surface direction and outputs the light to the front surface side. Are placed facing each other.

The light guide plate 22 is made of a rectangular transparent acrylic resin plate having a size facing at least the entire display area of the liquid crystal display panel 10. On the back surface side thereof, the entire back surface of the light guide plate 22 is provided. A reflecting plate 23 is disposed so as to face the.

Further, the light source lamp 21 includes the light guide plate 22.
The light source lamp 21 is arranged along one end surface of the light guide plate 22, and the light from the light source lamp 21 is behind the light source lamp 21. A reflector 24 that reflects the light toward the end surface of the light guide plate 22.
Is provided.

On the other hand, the light accumulating means 25 is formed by arranging a large number of dot-shaped light accumulating films 25a on the rear surface of the light guide plate 22 at a fine pitch over substantially the entire surface thereof. The dot-shaped light-storing film 25a stores light and emits light, and is formed by applying a light-storing luminescent paint to the entire back surface of the light guide plate 22 and patterning the film into a large number of dots by a photolithography method. Has been done.

FIG. 2 is an enlarged plan view of a part of the back surface of the light guide plate 22. Each dot-shaped light storage film 25a is formed by the light guide plate 2.
2 are arranged and formed at a constant pitch in the length direction and the width direction. The diameter of the dot-shaped luminous film 25a is 0.2 mm to
The arrangement pitch is about 0.8 mm / m at about 0.7 mm. In this embodiment, the dot-shaped luminous film 2
Although 5a is formed in a circular shape, this dot-shaped luminous film 25
The shape of a is not limited to a circular shape, and may be any shape such as a square shape.

The dot-shaped light storage film 25a is formed on the light guide plate 22.
The dot-shaped light-storing film 25a is for absorbing the light guided through the inside and incident on each dot-shaped light-storing film 25a and storing the light, and reflecting a certain amount of the incident light on the light-storing film surface. 2 is formed to be smaller as the intensity of light incident on each dot-shaped light storage film 25a increases, as shown in FIG.

That is, the light from the light source lamp 21 enters the light guide plate 22 from one end surface thereof, and the light guide plate 2
The light is incident on each dot-shaped light-storing film 25a in the process of being guided to the other end while refracting inside 2 by its front and back surfaces, but this light is attenuated as it is guided inside the light guide plate 22. Therefore, the intensity of light incident on each dot-shaped light storage film 25a becomes weaker as the distance from the light source lamp 21 increases.

The dot-shaped light-storing film 25a stores the light supplied to the light-storing film 25a and emits light of high brightness which is equal to or higher than the visual level which the human eye feels to have sufficient brightness. Since the emission brightness is almost proportional to the intensity of the supplied light, the emission brightness of the dot-shaped light storage film 25a becomes lower as the distance from the light source lamp 21 increases.

Therefore, in this embodiment, each dot-shaped light-storing film 25a is larger as it is farther from the light source lamp 21,
The closer to the light source lamp 21, the smaller the light emission intensity of each dot-shaped light-storing film 25a, and the smaller the light-emission brightness of each dot-shaped light-storing film 25a is.

However, the light guided to the other end inside the light guide plate 22 is reflected by the other end surface of the light guide plate 22 and enters the dot-shaped light storage film 25a in the vicinity thereof, so that the light guide plate 22
In the vicinity of the other end of the dot-shaped light-storing film 25a, the emission brightness of the dot-shaped light-storing film 25a increases conversely as it approaches the end.
The size of 5a is made smaller to some extent as it approaches the other end of the light guide plate 22, so that even near the other end of the light guide plate 22,
The light emission amounts of the respective dot-shaped light-storing films 25 are made substantially equal to each other.

FIG. 3 is a diagram showing the luminance distribution of the light emitted by each of the dot-shaped light-storing films 25a along the length direction of the light guide plate 22, and all the dot-shaped light-storing films 25a have the same size. The brightness distribution at this time is a distribution in which the brightness decreases as the distance from the light source lamp 21 is increased as shown by the chain line in the figure, but as the intensity of light incident on each dot-shaped phosphorescent film 25a increases. The dot-shaped light-storing films 25a are formed small, that is, the size of each dot-shaped light-storing film 25a is made different so as to be substantially inversely proportional to the intensity of the incident light.
If the amounts of light emission in the entire film are made substantially equal, the luminance distribution becomes a substantially uniform distribution as shown by the solid line in the figure.

The backlight device 20 causes the light from the light source lamp 21 to be stored in each dot-shaped light-storing film 25a constituting the light-storing means 25, and the light emitted by these dot-shaped light-storing films 25a is diffused to the light guide plate 22 and the diffusion plate. The light is emitted to the liquid crystal display panel 10 through the plate 27, and the dot-shaped light-storing film 25a stores and emits the light guided through the light guide plate 22 while the light source lamp 21 is on, and emits the light. It continues to emit light for a long time even after is turned off.

That is, the backlight device 20 is
The dot-shaped phosphorescent film 25a is used to emit high-luminance light for a long time by utilizing the phosphorescent film.
Stores the light supplied to the light-storing film, emits light with high brightness equal to or higher than the visual level, and keeps the light emission for a long time even after the supply of light is cut off.

For example, the luminous phosphorescent paint has a composition of 2
The residual brightness after irradiation of 00 lux for 4 minutes is 10
After 200 minutes, 200 mcd / m ² , after 300 minutes, 30 mcd / m ² .
It is as m ^2, since chromatic luminous level luminance feel human eye has sufficient brightness is 0.32mcd / m ^2, by forming the dot-like phosphorescent film 25a by using the luminous paint Even after the light source lamp 21 is turned off, high-intensity light can be obtained for a long time.

Therefore, according to the backlight device 20 described above, even if the light source lamp 21 is not always turned on,
Since light of sufficient brightness can be continuously emitted, power consumption can be significantly reduced.

In the backlight device 20 as well, the light source lamp 21 must be turned on until sufficient light is stored in the dot-shaped light-storing film 25a, but the time may be short and the time may be longer. If the light source lamp 21 is automatically turned off after the passage of, it is possible to eliminate wasteful power consumption in the light source lamp 21.

Moreover, the backlight device 2 of this embodiment
In No. 0, the dot-shaped light-storing films 25a are arranged at a constant pitch, and these dot-shaped light-storing films 25a are formed in a size that is substantially inversely proportional to the intensity of light incident on each dot-shaped light-storing film 25a. Therefore, each dot-shaped luminous film 25a
Even if the intensity of the incident light on the dot-shaped light-storing film 25a differs and the emission brightness of each dot-shaped light-storing film 25a differs accordingly, the amount of light emitted by the dot-shaped light-storing film 25a is made substantially equal to the whole film. As indicated by the solid line, the brightness distribution of the emitted light can be made substantially uniform.

The backlight device 20 is of a sidelight type, but in this embodiment, the light source lamp 21 is arranged so as to face one end surface of the light guide plate 22, and the light accumulating means 25 is arranged so as to guide the light. The dot-shaped light-storing film 25a is formed on the back surface of the light plate 22, and a diffusion plate 27 for diffusing the light emitted to the surface of the light guide plate 22 is provided on the front surface side of the light guide plate 22. The light guided through the light plate 22 is stored in the dot-shaped light storage film 25a, and the light emitted by the dot-shaped light storage film 25a is diffused by the diffusion plate 27, so that light having a continuous and uniform brightness distribution is obtained. Can be emitted.

Further, in this embodiment, since the dot-shaped light storage film 25a is formed on the back surface of the light guide plate 22, of the light guided through the light guide plate 22 and incident on the dot-shaped light storage film 25a. A certain amount of light can be reflected by the surface of the light storage film 25a and emitted to the surface side of the light guide plate 22. Therefore, while the light source lamp 21 is lit, the light is accumulated in the dot-shaped light storage film 25a while the light source lamp 21 is being illuminated. The light from can be emitted to the liquid crystal display panel 10.

While the light source lamp 21 is turned on, the light guided through the light guide plate 22 also leaks to some extent to the back surface side of the light guide plate 22 from the portion between the dot-shaped light-storing films 25a. The light is reflected by the reflection plate 23 arranged on the back surface side of the light plate 22 and accumulated in the dot-shaped light accumulation film 25a,
Alternatively, the light is emitted to the surface side of the light guide plate 22 through the portion between the dot-shaped light storage films 25a.

In the above embodiment, each dot-shaped light-storing film 25a forming the light-storing means 25 is formed on the back surface of the light guide plate 22, but the dot-shaped light-storing film 25a is formed on the light guide plate 2.
2 may be formed on the surface of the light guide plate 22.
If the diffuser plate 27 is provided on the surface side of the above, the light emitted from each dot-shaped light storage film 25a can be diffused by the diffuser plate 27, and the light with a smooth brightness distribution can be emitted.

FIG. 4 shows a second embodiment of the present invention,
FIG. 6 is an enlarged plan view of a part of the back surface of the light guide plate 22. In this embodiment, each dot-shaped light-storing film 25 constituting the light-storing means 25 is used.
a are arranged on the back surface of the light guide plate 22 at a constant pitch, and these dot-shaped light-storing films 25a are arranged in the respective dot-shaped light-storing films 25a.
The larger the intensity of light incident on the light guide plate 22, the smaller the light intensity.
A large number of dot-shaped reflective films 26 for reflecting the light guided in the light guide plate 22 to the surface side of the light guide plate 22 are provided at a constant pitch in correspondence with the portion between the dot-shaped reflective films. 26 is formed smaller as the intensity of light incident on each dot-shaped reflection film 26 increases.

In this embodiment, the dot-shaped light storage film 2 is used.
5a and the dot-shaped reflection film 26 are formed in a circular shape, the shapes of the dot-shaped luminous film 25a and the dot-shaped reflection film 26 are not limited to a circular shape, and may be any shape such as a square shape.

According to this embodiment, even if there is a difference in the amount of light reflected by the entire dot-shaped light-storing film 25a when the light source lamp is turned on, the difference is reflected by each dot-shaped reflective film 2a.
The intensity distribution of the emitted light when the light source lamp is turned on can be made more uniform by compensating for the amount of reflected light in the entire film of No. 6 than in the case of only the dot-shaped light storage film 25a.

That is, in the above-described first embodiment, since each dot-shaped light storage film 25a is formed to have a size that is substantially inversely proportional to the intensity of the incident light, the incident light to each dot-shaped light storage film 25a is formed. Even if the intensities are different, the amount of light emitted by the dot-shaped light-storing films 25a can be made substantially equal to each other, but even in that case, the amount of reflected light by the entire film of each dot-shaped light-storing film 25a is almost always. Not necessarily equal.

Therefore, in this embodiment, a large number of dot-shaped reflection films 26 are provided on the back surface of the light guide plate 22 at a constant pitch so as to correspond to the portions between the dot-shaped light storage films 25a. 26 is formed to have a smaller intensity as the intensity of the incident light increases, that is, a size that is substantially inversely proportional to the intensity of the incident light. With such a configuration, each dot when the light source lamp is turned on is formed. Luminous film 25a
The difference in the amount of reflected light in the entire film is compensated by the amount of reflected light in the entire film of each dot-shaped light-storing film 26, and the luminance distribution of the emitted light when the light source lamp is turned on becomes more uniform.

FIG. 5 is a sectional view of a liquid crystal display module equipped with a backlight device, showing a third embodiment of the present invention. Since the case 1 and the liquid crystal display panel 10 of this liquid crystal display module are the same as those of the first embodiment described above, the description thereof will be omitted by giving the same reference numerals to the drawings.

The backlight device 30 of this embodiment is of a direct type, in which the light source lamp 31 is arranged on the back surface side of the diffusion plate 32 for diffusing light, and the light storage means 35 serves as the back surface of the diffusion plate 32. The dot-shaped light-storing film 35a is formed in the structure.

In this embodiment, a plurality of (two in FIG. 5) light source lamps 31 are arranged on the back side of the diffuser plate 32 at appropriate intervals, and the diffuser plate 32 and the diffuser plate 32 are provided behind these light source lamps 31. The reflection plate 33 having substantially the same area is provided.

Further, in this embodiment, the light accumulating means 35 is used.
The dot-shaped light-storing films 35a constituting the above are arranged at a constant pitch, and the dot-shaped light-storing films 35a are arranged in accordance with the luminance distribution of the light from the light source lamp 31. The larger the intensity is, the smaller it is, that is, the size is almost inversely proportional to the intensity of the incident light.

In the backlight device 30 of this embodiment, the light from the light source lamp 31 is stored in each dot-shaped light storage film 35a, and the light emitted by these dot-shaped light storage films 35a is diffused by the diffusion plate 32 and the liquid crystal. The light is incident on the display panel 10, and in the backlight device 30 as well, the dot-shaped light-storing film 35a stores the light supplied to the light-storing film and emits light of high brightness equal to or higher than that level. Since the light emission continues for a long time even after the supply of light is cut off, it is possible to continuously emit light of sufficient brightness without constantly turning on the light source lamp. Can be significantly reduced.

Further, according to the backlight device 30, each dot-shaped light-storing film 35a forming the light-storing means 35 is formed on the back surface of the diffusion plate 32, that is, on the side on which the light from the light source lamp 31 is incident. , Each dot-shaped luminous film 35a
It is possible to diffuse the light emitted by the diffuser plate 32 to emit light having a smooth and uniform luminance distribution.

Further, in this embodiment, the dot-shaped light-storing films 35a are arranged at a constant pitch, and the dot-shaped light-storing films 35a are substantially inversely proportional to the intensity of light incident on each dot-shaped light-storing film 35a. However, even if the intensity of the incident light on each dot-shaped phosphorescent film 35a differs and the emission brightness of each dot-shaped phosphorescent film 35a differs accordingly, these dot-shaped phosphorescent films 35a It is possible to make the light emission amounts of the entire film substantially the same so that the luminance distribution of the emitted light becomes substantially uniform.

The liquid crystal display module shown in FIGS. 1 and 5 uses the liquid crystal display panel 10 having both the transmissive display type and the reflective type display function. It can be applied to a backlight device of a liquid crystal display module that uses a dedicated liquid crystal display panel (which does not have a reflection plate on the back surface), and is widely applied not only to the liquid crystal display module but also to a backlight device of various display devices. be able to.

[0056]

The backlight device of the present invention comprises a light source lamp and a light accumulating means in which a large number of dot-like light accumulating films for accumulating and emitting light are arranged at a minute pitch, and the light from the light source lamp is aforesaid light accumulating light. Each dot-shaped phosphorescent film that constitutes the means stores light and emits the light emitted by these dot-shaped phosphorescent films, so that light of sufficient brightness can be maintained even if the light source lamp is not always turned on. Therefore, the power consumption can be significantly reduced.

In the backlight device of the present invention, the dot-shaped light-storing films are arranged at a constant pitch, and the dot-shaped light-storing films are formed to be smaller as the intensity of light incident on each dot-shaped light-storing film increases. For example, even if the intensity of the incident light on each of the dot-shaped light-storing films is different and the emission brightness of each of the dot-shaped light-storing films is accordingly different, the light-emission amounts of these dot-shaped light-storing films are almost the same. As a result, the brightness distribution of the emitted light can be made substantially uniform.

When the present invention is applied to a side-light type backlight device, the light source lamp faces the end surface of the light guide plate which guides the incident light from the end surface in the surface direction and emits the light to the front surface side. And arrange it, and the phosphorescent means,
A dot-shaped light-storing film is formed on either one of the front and back surfaces of the light guide plate, and on the front surface side of the light guide plate, a diffusion plate for diffusing light emitted to the surface of the light guide plate is provided. It is possible to store the light guided through the light guide plate in the dot-shaped light-storing film, diffuse the light emitted by the dot-shaped light-storing film by the diffusion plate, and emit light with a smooth and uniform luminance distribution. .

In this case, the dot-shaped light-storing film is formed on the back surface of the light guide plate, and the light reflected in the light-storing film surface out of the light guided through the light guide plate and incident on the dot-shaped light-storing film is guided. If the light is emitted to the surface side of the light plate, the light from the light source lamp can be emitted while the dot-shaped light accumulation film is being accumulated while the light source lamp is lit.

When the dot-shaped light-storing films are formed on the back surface of the light guide plate, the dot-shaped light-storing films are arranged at a constant pitch, and these dot-shaped light-storing films are incident on the respective dot-shaped light-storing films. The larger the strength of, the smaller it is formed.
On the back surface of the light guide plate, a plurality of dot-shaped reflective films that reflect the light guided in the light guide plate to the front surface side of the light guide plate are provided at a constant pitch in correspondence with the portions between the dot-shaped light storage films. If these dot-shaped reflective films are made smaller as the intensity of the light incident on each dot-shaped reflective film becomes smaller, the reflection of the entire dot-shaped luminous film when the light source lamp is turned on is provided. Even if there is a difference in the amount of light, the difference can be compensated for by the amount of light reflected by the entire dot-shaped light-storing film, and the brightness distribution of the emitted light when the light source lamp is turned on can be made more uniform. .

When the present invention is applied to a direct type backlight device, the light source lamp is arranged on the back surface side of the diffusion plate for diffusing light, and the light storage means is provided on the back surface of the diffusion plate in the form of a dot-shaped light storage film. If it is configured to form, the light from the light source lamp is stored in the dot-shaped light-storing film, the light emitted by the dot-shaped light-storing film is diffused by the diffusion plate, and the light having a gentle brightness distribution is emitted. be able to. Again,
While arranging the dot-shaped luminous film at a constant pitch,
If these dot-shaped light-storing films are made smaller as the intensity of the light incident on each dot-shaped light-storing film becomes smaller, the luminance distribution of the emitted light can be made substantially uniform.

[Brief description of the drawings]

FIG. 1 is a sectional view of a liquid crystal display module including a backlight device according to a first embodiment of the present invention.

FIG. 2 is an enlarged plan view of a part of the back surface of the light guide plate in the first embodiment.

FIG. 3 is a diagram showing a luminance distribution of light emitted by each dot-shaped phosphorescent film in the first embodiment along the length direction of the light guide plate.

FIG. 4 is an enlarged plan view of a part of the back surface of the light guide plate, showing the second embodiment of the present invention.

FIG. 5 is a sectional view of a liquid crystal display module having a backlight device according to a third embodiment of the present invention.

[Explanation of symbols]

 10 ... Liquid crystal display panel 20, 30 ... Backlight device 21, 31 ... Light source lamp 22 ... Light guide plate 25, 35 ... Luminous storage means 25a, 35a ... Dot luminous film 26 ... Dot reflective film 27, 32 ... Diffusion plate

Claims (6)

[Claims] 1. A light source lamp, and a light storing means in which a large number of dot-shaped light storing films that store and emit light are arranged at a fine pitch, and the light from the light source lamp is applied to each dot-shaped light storing film of the light storing means. A backlight device, characterized in that after the light source lamp is turned off, the light emitted by each of the dot-shaped light storing films is emitted as illumination light. 2. The dot-shaped light-storing films are arranged at a constant pitch, and the dot-shaped light-storing films are formed smaller as the intensity of light incident on each dot-shaped light-storing film increases. The backlight device according to claim 1. 3. The light source lamp is arranged so as to face the end surface of a light guide plate which guides the incident light from the end surface in the surface direction and emits the light to the surface side, and the light storing means is arranged on the surface of the light guide plate. It is configured by forming a dot-shaped light-storing film on either one of the back surface, and a diffusion plate for diffusing light emitted to the surface of the light guide plate is provided on the front surface side of the light guide plate. The backlight device according to claim 1 or 2. 4. A dot-shaped luminous film is formed on the back surface of the light guide plate,
4. The backlight according to claim 3, wherein, of the light guided through the light guide plate and incident on the dot-shaped light storage film, the light reflected on the light storage film surface is emitted to the front surface side of the light guide plate. apparatus. 5. The dot-shaped light-storing films are arranged at a constant pitch, and these dot-shaped light-storing films are formed smaller as the intensity of light incident on each dot-shaped light-storing film increases, and the light guide plate is formed. A large number of dot-shaped reflective films for reflecting the light guided in the light guide plate to the front surface side of the light guide plate are provided at a constant pitch on the back surface of the light guide plate in correspondence with the portions between the dot-shaped light storage films. The backlight device according to claim 4, wherein the dot-shaped reflective films are formed to be smaller as the intensity of light incident on each dot-shaped reflective film is larger. 6. The light source lamp is arranged on the back surface side of a diffusion plate for diffusing light, and the light storage means is formed by forming a dot-shaped light storage film on the back surface of the diffusion plate. The backlight device according to claim 1 or 2.