JP2001135118A - Panel light source device and flat display using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a panel light source device and a flat display capable of easily adjusting white balance in a wide range without causing the deterioration of picture quality such as a narrower dynamic range. SOLUTION: A panel light source device 1 as a backlight or a frontlight uses a fluorescent lamp 12 and LED lamps 11-R, 11-G, 11-B for respective colors, as light source. With the adjustment of the quantity of emission light of the LED lamps 11-R, 11-G, 11-B for respective colors, the adjustment of the white balance of illumination light and the improvement of color rendering properties are achieved without giving signal processing. Because of no need of signal processing, the deterioration of picture quality such as a narrower dynamic range of display signals is prevented in adjustment of white balance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface light source device and a flat display device using the same. In particular, the present invention relates to a surface light source device including an LED (light emitting diode) lamp and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art Flat display devices such as liquid crystal display devices take advantage of their features such as light weight and low power consumption.
It is widely used for personal computers, portable information devices, and the like, and various applications are considered. Hereinafter, a liquid crystal display device that displays an image by a matrix method will be described as an example.

[0003] As a liquid crystal display device capable of displaying an image, a transmission type in which a surface light source device called a backlight is disposed on the back side of a transmission type liquid crystal panel is currently the mainstream. However, a reflection type liquid crystal display device which can realize further light weight and low power consumption is also used. When the illuminance in the use environment is not enough,
Since a displayed image is difficult to recognize, a surface light source device called a front light is generally arranged on the display surface side, and external light and light from the front light are commonly used.

A schematic structure of a conventional transmission type flat panel display device is shown in a sectional view of FIG. The surface light source device 1 as a backlight includes a flat light guide 15, a fluorescent lamp 12 arranged along an end face of the light guide 15, a reflector 12 a (reflecting mirror) that covers the fluorescent lamp 12 from outside, And a reflector 14 that covers the light guide 15 from the back side. The transmissive liquid crystal panel 2 has a polarizing plate 21 disposed on the display surface and the back surface thereof, and is mounted on the surface light source device 1.

[0005] Light emitted from the fluorescent lamp 12 is directly incident on the light guide 15 or is reflected by the reflector 12a and is incident on the light guide 15. In the illustrated example, the light guide 15 has a shape that becomes thinner as the distance from the fluorescent lamp increases, and the light from the fluorescent lamp passes through the inclined interface 1 on the back side.
The light is reflected by 5a or reflected by the reflection plate 14 and is incident on the liquid crystal panel 2. When the backlight light incident on the liquid crystal panel 2 passes through the liquid crystal layer, it is modulated according to a display signal applied to each pixel of the liquid crystal panel 2 and emitted to the display surface side. As a result, an image is displayed.

Next, a schematic structure of a conventional reflection type flat display device provided with a front light is shown in a sectional view of FIG.

When used in a bright environment, that is, when ambient light (external light) is sufficient, an image display with sufficient luminance can be obtained only by external light. In this case, incident light from the display surface side passes through the light guide 15 of the front light,
The light is reflected on the back surface side of the liquid crystal layer and emitted from the display surface side.
When the incident light reciprocates through the liquid crystal layer, it is modulated according to the display signal and emitted, whereby an image is displayed.

When the external light is not sufficient, a display which is sufficiently easy to read is obtained by illuminating with a front light. The front light has substantially the same general structure as that of the backlight except that the front light is not provided with the reflection plate 14.
Illumination is performed by light from a fluorescent lamp 12 arranged along the end face of the light emitting element 5. The light from the fluorescent lamp 12 is reflected by an interface (inclined surface) 15 a on the display surface side of the light guide 15 having a shape that becomes thinner as the distance from the fluorescent lamp 12 increases, and enters the liquid crystal panel 2.

In the above backlight, brightness unevenness may occur depending on the design structure such as the relationship between the light guide 15 and the fluorescent lamp 12. In Japanese Patent Application Laid-Open No. 11-202330, a white LED lamp is provided at a place where the brightness becomes insufficient. 4 has been proposed (FIG. 13).

[0010]

However, in the case of the above-mentioned conventional flat display device, the chromaticity of white illumination light from the surface light source device cannot be adjusted.

Therefore, the white balance of the displayed image, that is, the chromaticity in performing white display, is determined by designing the fluorescent lamp and the color filter, that is, designing the emission wavelength distribution of the fluorescent lamp and the passing wavelength characteristic of the color filter. And could not be easily changed like a CRT (cathode ray tube display).

The white balance of a display image can be changed slightly by applying processing to an input display signal. In this case, however, there is a problem that display luminance is reduced, and a gradation display for a specific color is performed. There is a problem that the characteristics are deteriorated. The white balance is adjusted by changing the display signal by applying a predetermined bias signal to one or more of the red (R), green (G), and blue (B) color signals, or By changing the amplitude balance between these color signals. However, in such a biased display signal or a display signal in which the signal amplitude is variable, the dynamic range of the display signal cannot be effectively used, so that the above-described problem such as a decrease in display luminance occurs. is there.

[0013] Further, since the user cannot freely adjust the white balance, the user is given an impression that the usability is lower than that of the CRT in this respect.

In particular, in the case of a reflection type flat display device,
As described above, since an image is displayed by reflecting incident light from the surroundings, the white balance of the displayed image changes due to the incident light from the surroundings. For example, when the color temperature is high, such as light from a fluorescent lamp, and when the color temperature is low, such as light from an incandescent light bulb, image display of different colors is performed even if the input display signal is the same. Is performed.

Further, since the adjustment of the white balance by applying processing to the display signal can be performed only on the signal axis of each of the primary colors of RGB, a subtle adjustment of the color balance and a color rendering effect such as greatly changing the color balance can be achieved. Could not be expected.

On the other hand, in a surface light source device using a fluorescent lamp, there is a problem that the brightness of an image is reduced immediately after startup or when the device is used at a low temperature, and the visibility of a displayed image is reduced.
This is due to the following characteristics of the fluorescent lamp. Regardless of whether the fluorescent lamp is a cold-cathode tube or a hot-cathode tube, the amount of current is small when the electrode temperature is low, so that the amount of light emission is small. It will rise.

The present invention has been made in view of the above-mentioned problems, and can easily and widely adjust a white balance.
An object of the present invention is to provide a surface light source device and a flat display device which do not cause image quality deterioration such as narrowing a dynamic range.

[0018]

According to a first aspect of the present invention, there is provided a surface light source device for emitting illumination light to a display panel for displaying an image. A plurality of LED lamps that emit light, a plurality of lights from these LED lamps, or a mixture of the plurality of lights and other light sources, or external light, is emitted to the display panel as illumination light. It is characterized by comprising a mixed color light guiding means and a chromaticity adjusting means for adjusting the chromaticity of the illumination light by increasing or decreasing the light quantity of the plurality of LED lamps for each color or for each chromaticity.

With the above configuration, the white balance can be adjusted easily and over a wide range, and the image quality such as narrowing the dynamic range is not deteriorated.

According to a tenth aspect of the present invention, there is provided a flat panel display device comprising a display panel for displaying an image and a surface light source device disposed on the back side or the display surface side. A plurality of LED lamps that emit light of different colors, or each emit light of different chromaticity, and a plurality of lights from these LED lamps, or the plurality of lights and other light sources, or external light Adjusting the chromaticity of the illuminating light by increasing / decreasing the amount of light of the plurality of LED lamps for each color or for each chromaticity, and for mixing / mixing the light amount of the plurality of LED lamps; And a chromaticity adjusting means.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of a flat panel display device and a surface light source device according to the present invention will be described with reference to FIGS.

Embodiment 1 First, a flat panel display according to Embodiment 1 will be described with reference to FIGS. Here, the flat display device is a transmissive liquid crystal display device, and the surface light source device 1 is a backlight.

FIG. 1 is a schematic longitudinal sectional view of a flat panel display device, and FIG. 2 is a plan view of a surface light source device 1. As shown in FIG. 1, a polarizing plate 21 is provided on both sides of the surface light source device 1.
Is mounted thereon.

As shown in FIGS. 1 and 2, the surface light source device 1 comprises:
As a light source, a fluorescent lamp 12 and red (R), green (G) and blue (B) LED lamps 11-R, 11-G, 11-B
And

One long side 15a of the rectangular light guide 15
A single linear fluorescent lamp 12 is disposed on the side, and extends over the entire length of the side 15a. A plurality of LED lamps 11 are provided on the side of the long side
b are arranged over the entire length. LED lamp 11
Are the red (R) LED lamp 11-R, the green (G) LED lamp 11-G, and the blue (B) LED lamp 1.
1 are arranged so as to be repeated in this order.

As shown in FIG. 1, the light guide 15 is formed by superposing a light guide plate 16 for a fluorescent lamp and a light guide plate 17 for an LED. Each of the light guide plates 16 and 17 has a substantially wedge-shaped longitudinal section, and has a shape whose thickness decreases in proportion to the distance from the incident side end faces 16a and 17a. Since the light guide plates 16 and 17 are superimposed such that the thick incident side end faces are opposite to each other, the thickness of the entire light guide 15 is substantially uniform in the illustrated example.

The incident side end face 16 of the light guide plate 16 for a fluorescent lamp
The fluorescent lamp 12 arranged along the line a is covered by the reflector 12a from the outside. In addition, the light guide plate 1 for LED
Each of the LED lamps 11 disposed along the incident side end face 17a of the LED 7 is provided with a reflector 11a.
Light from the lamp 11 is directed to the light guide plate 16.

The back surface of the light guide 15, that is, the back surface of the LED light guide plate 16 is covered with the prism sheet 18.
As shown in the enlarged sectional view of FIG. 1, the prism sheet 18 has a saw-tooth shape with a uniform cross section. Reflective surface 18a. The light from the LED lamp 11 is reflected by these reflection surfaces 18a at an angle close to perpendicular to the inclined surfaces 16c and 17c of the LED and fluorescent lamp light guide plates 16 and 17 which are superimposed on each other. That is, the reflected light is reflected by the inclined surfaces 16c, 17
c so as not to be reflected again to the back surface side.

The light that reaches the prism sheet 18 includes not only the light directly emitted from the LED lamp 11 but also a part of the light emitted from the fluorescent lamp 12 and the other light from the light guide 15. Contains light that leaks out.

In the light guide 15, each LED lamp 11-
Light from R, 11-G, 11-B and light from the fluorescent lamp 12 are mixed. In order to improve color mixing, a diffusion pattern is printed on the inclined surface 16c of the LED light guide plate 16. You may. Each LED lamp 11-R, 11-G,
In order to sufficiently mix the colors from the light guides 11-B and uniformly emit light from the upper surface of the light guide 15, the distance between each LED lamp 11 and the incident side end face 16a of the LED light guide plate must be constant. Good to be. More specifically, it is preferable that the distance between the fluorescent lamp 12 and the incident side end face 17a of the fluorescent lamp light guide plate is made as uniform as the distance.

Next, a method of changing the chromaticity of illumination light from the surface light source device 1 (white balance of illumination light) will be described with reference to FIGS.

LED lamps 11-R, 11-G, 1 of each color
The light emission amount of 1-B can be increased or decreased by changing the effective value of the current flowing therethrough, and the white balance of the illumination light can be changed by changing the ratio of the effective values.

The current waveform diagram of FIG. 3 shows a case where the ratio of the effective value is changed by increasing or decreasing the current value itself.
In FIG. 3, only the amount of light emitted from the blue LED lamp 11-B is increased by increasing the amount of current flowing through the blue LED lamp 11-B. On the other hand, the current waveform diagram of FIG. 4 shows a case where the ratio of the effective values is changed by changing the duty ratio of the applied current. In FIG. 4, by increasing the inflow time of the current flowing through the blue LED lamp 11-B, the blue LED lamp 11-B is increased.
Only the amount of light emission is increased.

As described above, the LED lamps 11-R, 11-R
-G, 11-B, by increasing or decreasing the amount of current flowing for one of the colors, it is possible to change the chromaticity of the irradiation light of the LED lamp 11 as a whole, and therefore, the surface light source device The chromaticity of the entire illumination light from 1 can be changed.

Next, with reference to FIG. 5, a description will be given of how to solve the problem of insufficient luminance when the surface light source device 1 is activated.

As shown in FIG. 5A, the light emission amount of the fluorescent lamp 12 is low at the time of starting, gradually increases, and reaches a constant value after a while. This is because, due to the characteristics of the fluorescent lamp 12, the amount of light emission is low at a low temperature, and it takes some time from application of an electric current to temperature rise.

In the surface light source device of this embodiment, the LED
As shown in FIG. 5B, the current flowing through the lamp 11 is increased at the time of startup and gradually reduced so that it reaches a constant value after a while. That is, the LED lamp 11
The amount of light emitted from is changed as shown in FIG. 5C so as to compensate for the insufficient amount of light when the fluorescent lamp 12 is activated. As a result, as shown in FIG. 5D, the total value of the amount of light emitted from the fluorescent lamp 12 and the amount of light emitted from the LED lamp 11 becomes constant from the time when the switch is turned on to after the fluorescent lamp 12 is stabilized. It is to be.

As described above, by controlling the amount of current flowing through the LED lamp 11, in the surface light source device using the fluorescent lamp 12 as a main light source, a stable luminance can be obtained immediately after starting.

The case where the surface light source device 1 or the flat display device returns from the sleep state is performed in exactly the same manner as at the time of starting described above. The temperature of the fluorescent lamp 12 decreases and the amount of light emission decreases even when the temperature of the atmosphere is low, other than at the time of startup, but the light emission of the surface light source device is controlled by the LED lamp 11 as described above. A decrease in luminance can be prevented.

The method of supplying the driving current to the LED lamp 11 may be arbitrarily adjusted by the user, may be a sequential operation based on a preset value, or may be performed by the user in several different settings. Any of the set values may be selected from the values to operate based on the set values, or may be based on automatic control by a feedback system using a temperature sensor or the like.

Embodiment 2 FIG. 6 shows a flat panel display according to Embodiment 2.

The flat-panel display device of this embodiment has a surface light source device 1
Of the light guide 15 is not one from the two light guide plates 16 and 17 but one.
This is exactly the same as the flat display device of the first embodiment except that the light guide plate is made up of a plurality of substantially uniform thicknesses, and the back surface of the light guide 15 is covered by a reflection diffusion plate 19 instead of the prism sheet 18.

According to this embodiment, substantially the same effects as those of the first embodiment can be obtained.

Third Embodiment FIG. 7 shows a flat panel display according to a third embodiment.

The flat display device of this embodiment is a reflection type liquid crystal display device, and uses a surface light source device having the same configuration as that of the first embodiment as a front light. Therefore, the polarizing plate 21 is disposed only on the surface on the display surface side of the liquid crystal panel 2, that is, between the liquid crystal panel 2 and the light guide 15, and the reflection plate 22 covers the liquid crystal panel 2 from the back surface side. .

According to this embodiment, the thickness in the direction along the substrate surface can be made smaller, though the thickness is increased as compared with the flat display device of Embodiment 5 described later.

Fourth Embodiment FIG. 8 shows a flat panel display according to a fourth embodiment.

The flat display device of the present embodiment is a transmission type liquid crystal display device as in the first embodiment. However, the light guide 15
However, only one light guide plate similar to the light guide plate 16 for the fluorescent lamp of the first embodiment is used, and the rows of the LED lamps 11 and the fluorescent lamps 12 are arranged along the same long side of the rectangular light guide 15. You.

Along the incident side end face 15a of the light guide 15,
A pair of triangular prisms 13a and 13b for mixing light from the LED lamps 11-R, 11-G and 11-B of each color and light from the fluorescent lamp 12 are arranged. These triangular prisms 13a and 13b are substantially identical to each other,
Surfaces 13c corresponding to the hypotenuses of the triangular cross section (hereinafter referred to as prism oblique surfaces) 13c are combined so as to be almost perfectly fitted to each other to form one prism color mixer 13 having a substantially rectangular cross section. The surface of the prism color mixer 13 on the light guide 15 side has substantially the same size as the incident side end surface 15 a of the light guide 15.

The prism color mixer 13 is arranged such that one surface thereof is almost exactly fitted to the incident side end face 15a of the light guide 15, and the prism inclined surface 13c is away from the light guide 15 toward the display surface side. It is arranged so that it becomes. A row of LED lamps 11 exactly the same as in the first embodiment is arranged along the surface on the display surface side (upper side in the figure) of the prism color mixer 13. Further, along the outer surface of the prism color mixer 13, that is, the surface farther from the light guide 15,
The fluorescent lamp 12 and the fluorescent lamp reflector 12a are arranged exactly as in the first embodiment.

The back side (lower side in the figure) of the prism color mixer 13 is covered with a reflector 14 and a light guide 15
Is covered by the reflection diffusion plate 19 from the back side.

A part of the light emitted from the LED lamp 11 is reflected on the prism slope 13c and enters the light guide 15.

A part of the light from the fluorescent lamp 12 is also reflected at the prism inclined surface 13c and further reflected by the reflector 14, and then penetrates through the prism color mixer 13 to reflect the LED lamp reflector 11a and the fluorescent lamp. Is reflected again by the reflector 12a. Of this light, prism slope 1
The light incident on the light guide 3c at an angle almost perpendicular to the light guide 3c is incident on the light guide 15 through the prism slope 13c.

Also, of the light from the LED lamp 11,
Light that reaches the reflector 14 without being reflected at the prism slope 13c also enters the light guide 15 via the same path. Further, of the light from the fluorescent lamp 12, the light not reflected at the prism slope 13 c enters the light guide 15 as it is.

As described above, the light from the LED lamp 11 and the light from the fluorescent lamp 12 are combined by the prism color mixing device 1.
The light is mixed in the light guide 3 and irradiated to the light guide 15. Light guide 15
The light guided to the liquid crystal panel 2 is further illuminated on the liquid crystal panel 2 with the uniformity further increased by the action of the reflection diffusion plate 19.

The adjustment of the white balance of the illuminating light and the adjustment of the luminance at the time of starting and the like are performed in exactly the same manner as in the first embodiment.

According to the present embodiment, the thickness of the light guide 15 can be made smaller than that of the first embodiment, so that the flat display device can be made thinner.

Fifth Embodiment FIG. 9 shows a flat panel display according to a fifth embodiment.

The flat display device of this embodiment is a reflection type liquid crystal display device, and uses a surface light source device having the same configuration as that of the fourth embodiment as a front light. Therefore, the polarizing plate 21 is disposed only on the surface on the display surface side of the liquid crystal panel 2, that is, between the liquid crystal panel 2 and the light guide 15, and the reflection plate 22 covers the liquid crystal panel 2 from the back surface side. .

In a state where the illumination light from the surface light source device 1 is not used, only light from the outside is emitted from the light guide 15 and the polarizing plate 21.
And enters the liquid crystal panel 2. The light incident on the liquid crystal panel 2 is modulated in the liquid crystal layer and reaches the reflection plate 22, is reflected by the reflection plate 22, is modulated again in the liquid crystal layer, and is further polarized by the polarization plate 21. Thus, an image is displayed by the light emitted through the light guide 15.

When performing illumination by the surface light source device 1,
In the light guide 15, the light from the outside and the light from the surface light source device are mixed and irradiated to the liquid crystal panel 2. Then, as in the case of only the external light, the liquid crystal panel 2, the polarizing plate 2
The light is emitted toward the display surface side under the action of 1 and the reflection plate 22, and is observed as a display image.

In the reflection type flat display device using such external light, according to the prior art, there is a problem that the display color of a display image differs due to the external light. The difference in the chromaticity of the displayed image between the case where the flat display device is used under sunlight and the case where the flat display device is used under indoor illumination light is different from the wavelength region of the monochromatic light included in the external light and the light amount distribution. It happened. In addition, since the chromaticity of the illumination light in the surface light source device could not be changed, the chromaticity of the entire illumination light could not be kept constant in response to such a change in external light.

In the reflective flat panel display according to the present invention, the light amount balance between the colors of the LED lamps 11-R, 11-G, and 11-B of each color is variable, and this light amount balance is appropriately adjusted. , The chromaticity of the display image can be adjusted.

Embodiment 6 FIG. 10 shows a surface light source device according to a flat panel display device of Embodiment 6.

The flat panel display according to the present embodiment has the same structure as that of the first embodiment, but has a yellow LED lamp 11-Y.
As shown in the figure, a row of the LED lamps 11 includes a red (R) LED lamp 11-R, a green (G) LED lamp 11-G, a blue (B) 11-B, and a yellow LED. The lamps 11-Y are arranged so as to be repeated in this order.

The light from the LED lamps 11 of each color generally has almost a single wavelength and does not come from a wide light emission band unlike the fluorescent lamp 12. Therefore, when only the red (R), green (G), and blue (B) LED lamps 11-R, 11-G, and 11-B are used as in the above-described first to fifth embodiments, each of the RGB components is used. Although it is easy to adjust the chromaticity of the mixed illumination light on the axis, there is a problem that color rendering is generally lacking.

Therefore, in the present embodiment, the adjustment between the red (R) and the green (G), that is, the adjustment of the yellow (Y) color component is facilitated by providing the yellow LED lamp 11-Y. Can be done.

As described in the first embodiment, the white balance of the illuminating light, the change of the color tone, and the like are changed as described in the first embodiment.
The adjustment is performed by adjusting the effective value of the current for driving the D lamps 11-R, G, and B. Further, the illumination light by the entire LED lamp 11 is not limited to white, and can be freely selected.

As described above, the fluorescent lamp having a plurality of emission wavelengths and the LE of each color having a single emission wavelength are provided.
A surface light source device as a backlight or a front light is configured from the D lamp, and the amount of light emitted from the LED lamp of each color is made variable, so that the white balance can be adjusted and the color rendering properties can be improved without performing signal processing. Can be realized. Since signal processing is not required, image quality deterioration such as narrowing of the dynamic range of a display signal does not occur in white balance adjustment.

In the above, the case where the fluorescent lamp and the LED lamp are used together has been described. However, a surface light source device using only the LED lamp as the light source can be used, and the light source other than the fluorescent lamp and the LED lamp can be used together. You can also.

It is also possible to use a plurality of white light LEDs having different chromaticities as the LED lamp. Furthermore, if the amount of light from other light sources other than the LED lamp can be adjusted, the chromaticity of the illumination light may be adjusted by adjusting the balance between the light from the LED lamp and the other light source light. Is possible.

[0072]

According to the present invention, there is provided a surface light source device and a flat display device which can easily and widely adjust a white balance and do not cause deterioration of image quality such as narrowing of a dynamic range.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically illustrating a flat panel display device according to a first embodiment.

FIG. 2 is a plan view schematically showing a surface light source device according to the flat display device of Example 1.

FIG. 3 is a current waveform diagram in a case where the ratio of the effective value is changed by increasing or decreasing the current value flowing through the LED lamp of each color.

FIG. 4 is a current waveform diagram in a case where the ratio of the effective value is changed by changing the duty ratio of the current flowing through the LED lamp of each color.

FIG. 5 is a series of waveform charts for explaining the elimination of insufficient luminance immediately after activation of the surface light source device. FIG.
(A) shows a change in the light emission amount of the fluorescent lamp immediately after startup. FIG. 5B shows the amount of current flowing to the LED lamp immediately after startup. FIG. 5C shows a change in the light emission amount of the LED lamp immediately after startup. FIG. 5D is a waveform diagram of a total value of the light emission amount from the fluorescent lamp and the light emission amount from the LED lamp, and shows a state where the total value is kept constant.

FIG. 6 is a longitudinal sectional view schematically illustrating a flat panel display device according to a second embodiment.

FIG. 7 is a longitudinal sectional view schematically illustrating a flat panel display device according to a third embodiment.

FIG. 8 is a longitudinal sectional view schematically illustrating a flat panel display device according to a fourth embodiment.

FIG. 9 is a longitudinal sectional view schematically illustrating a flat panel display device according to a fifth embodiment.

FIG. 10 is a plan view schematically showing a surface light source device according to a flat panel display device of Example 6.

FIG. 11 is a longitudinal sectional view showing a schematic structure of a conventional transmission type flat panel display device.

FIG. 12 is a longitudinal sectional view schematically showing the structure of a conventional reflection type flat panel display device having a front light.

FIG. 13 is an exploded perspective view schematically showing a conventional flat panel display device provided with a white LED lamp in a surface light source device.

[Explanation of symbols]

1 surface light source device 11 LED lamps 11-R, 11-G, 11-B Red (R), green (G) and blue (B) LED lamps 11a LED lamp reflector 12 Fluorescent lamp 12a Fluorescent lamp reflector 13 Mixer consisting of prisms 14 Reflector 15 Light guide 16 Light guide for LED 17 Light guide for fluorescent lamp 18 Prism sheet 19 Reflective diffuser 2 Liquid crystal panel 21 Polarizer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F21Y 103: 00 G02F 1/1335 530 F-term (Reference) 2H091 FA08X FA08Z FA14Z FA21Z FA23Z FA42X FA42Z FA45X FA45Z FD11 LA15 LA18 LA20 5G435 AA04 AA14 BB03 BB04 CC12 DD11 EE27 EE29 FF05 GG03 GG26 GG27

Claims (10)

[Claims] 1. A surface light source device for emitting illumination light to a display panel for displaying an image, comprising: a plurality of LED lamps each emitting light of a different color or emitting light of a different chromaticity; A plurality of lights, or a mixture of these lights and other light sources, or mixed light with external light, to emit light to the display panel as illumination light, and a light amount of the plurality of LED lamps. Chromaticity adjusting means for adjusting the chromaticity of the illumination light by increasing or decreasing the chromaticity for each color or for each chromaticity. 2. The surface light source device according to claim 1, further comprising a fluorescent lamp as another light source, wherein said mixed light guide means mixes light of said fluorescent lamp and light of said LED lamp. 3. The surface light source device according to claim 1, wherein the plurality of LED lamps include red (R), green (G), and blue (B) LED lamps. 4. The light guide according to claim 1, wherein said light guide means comprises a substantially rectangular flat light guide, and said plurality of light guides extend along one end face of said light guide.
The surface light source device according to claim 2, wherein ED lamps are arranged, and the fluorescent lamp is arranged along an end face of the light guide, which faces the one end face. 5. The light guide according to claim 1, wherein the light guide is a light guide plate for a fluorescent lamp.
5. The surface light source device according to claim 4, wherein the light guide plate for D is overlapped. 6. The color mixing light guide means comprises a substantially rectangular flat light guide, and a prism color mixer arranged along an end face of the light guide and combining a plurality of prisms. The surface light source device according to claim 2, wherein the plurality of LED lamps are arranged along one incident surface of the prism color mixer, and the fluorescent lamps are arranged along another incident surface. 7. The illuminant according to claim 1, wherein the surface light source device is a front light used in a reflective flat panel display device, and the chromaticity adjusting means adjusts the chromaticity of the illumination light in accordance with a change in chromaticity or light amount of external light. 2. The surface according to claim 1, further comprising an external light fluctuation compensation function for compensating for the fluctuation by adjusting chromaticity and light amount, and for keeping chromaticity of a display image constant when white display is performed. Light source device. 8. The plurality of LED lamps so as to compensate for the decrease in light amount of the fluorescent lamp immediately after starting or when the light amount decreases from a predetermined steady-state value when used in a low-temperature environment. 3. The surface light source device according to claim 2, wherein the amount of light is increased as a whole. 9. The system according to claim 3, further comprising an LED that emits an intermediate color of any one of the red (R), green (G), and blue (B) as the plurality of LED lamps. The surface light source device as described in the above. 10. A flat panel display device comprising a display panel for displaying an image and a surface light source device disposed on the back side or the display surface side, wherein the surface light source devices emit light of different colors. ,
Or a plurality of LED lamps each emitting light of different chromaticity, and a plurality of lights from these LED lamps, or the plurality of lights and other light source light, or by mixing with external light, A color mixing light guide unit that emits light to a display panel; and a chromaticity adjustment unit that adjusts the chromaticity of the illumination light by increasing or decreasing the light amount of the plurality of LED lamps for each color or for each chromaticity. A flat display device characterized by the above-mentioned.