JPH11185515A - Front-light type lighting system, and reflection type liquid crystal display device with front-light type lighting system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin type front-light type lighting system not degrading display quality of a reflection type color liquid crystal panel, and the like. SOLUTION: A transparent substrate 3a is disposed opposite to a reflection type color liquid crystal panel 4 with a fixed gap 3a left by the reflection type color liquid crystal panel 4, and an incident angle in the thickness direction of the gap 3a of light from an LED 1 is narrowed down by a micro-prism type collimator 2, therefore much of light progressing in the direction opposite to a display surface of the reflection type color liquid crystal panel 4, of light coming into the gap 3a, is reflected by the transparent substrate 3, the reflected light acts as illuminating light, and therefore uniform illumination can extend as far as parts remote from the LED 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front light type illuminating device used for a reflection type color display device and the like, and a reflection type liquid crystal display device with a front light type illuminating device.

[0002]

2. Description of the Related Art In recent years, as a display device for a portable information device,
Various types of reflective color display devices using liquid crystals have been developed. These reflective color display devices generally have a configuration in which a reflective layer and a color filter are formed on the inner surfaces of two electrode substrates sandwiching a liquid crystal layer. Such a device is described in, for example, Nikkei Microdevice October 1996, p.
2 and 23rd Liquid Crystal Symposium Proceedings P124 Figure 1, Nikkei Microdevice October 1997 P135 Figure 2,
IEICE Technical Report Vol97No. 211P14, 15 and the like.

[0003] Since such a reflective color display device has a reflective layer, a conventional backlight cannot be used at night or in a dark place. A lighting device is required. This front light type lighting device is SID95DIGEST, P37
6, proposed in FIG. FIG. 7 schematically shows this.

[0004] The illumination principle of FIG. 7 will be briefly described. Light emitted from a fluorescent lamp 101 for illumination enters the light guide plate 102 from a side surface 102 a of the light guide plate 102, and is emitted by a microprism 102 b formed on the display surface side. The light is reflected to the lower side of the drawing and illuminates a reflective color display device (not shown) installed at the lower side of the drawing. In addition, the light guide plate 10
An inclined prism 102c is provided on the side of the side surface 102a of the light guide plate 2 so as to narrow the incident angle of the light emitted from the fluorescent lamp 101 for illumination in the thickness direction of the light guide plate 102 to reduce the light guide plate 1
02 is reflected by the microprism 102b downward in the drawing. Note that 103
Is a reflection plate, and 104 is an optical compensator.

[0005]

However, when the above-mentioned device is used as a display lighting device, the display is viewed through a light guide plate formed with micro prisms.
The light scattered at the edge of the prism or the like enters the eyes of the observer, causing the display to appear slightly white, and has a problem that a clear display cannot be obtained.

Further, since a light guide plate having a microprism formed on the entire screen is used, it is expensive and there is a problem in terms of cost. In addition, when an optical compensator as shown in FIG. 7 is provided, the cost is further increased. In addition, since a light guide plate having a microprism formed on the entire screen is used, when a point light source such as an LED is used as a light source, an LED is used.
And the light guide plate 10
From No. 2, uniform surface illumination could not be obtained. That is, when viewed from the front side, it appears that linear light is emitted from the LED chip in a direction perpendicular to the groove of the prism of the light guide plate 102, which is not practical as a lighting device.

Further, since the prism has a reflection direction,
The light source can be installed only in one direction, and there are restrictions on brightening the light source.

[0008]

According to the present invention, a transparent substrate is disposed so as to be opposed to a display unit to be illuminated with a predetermined gap, and the light from the light source is narrowed by a narrowing unit. Since the angle of incidence in the thickness direction of the gap is narrowed down,
Of the light that enters the gap from the light source, the light that travels in the direction opposite to the display surface is also reflected by the transparent substrate, and the reflected light acts as illumination light, so that illumination efficiency is improved. Further, since the angle of incidence of the light from the light source in the thickness direction of the gap is narrowed by the narrowing means, most of the light from the light source traveling in the direction opposite to the display surface can be reflected by the transparent substrate. In addition, light reaches far away from the light source, and the illumination efficiency is further increased, and uniform bright illumination can be achieved. Further, when there is no narrowing means, it is necessary to install the illumination at a high position in order to uniformly illuminate the entire screen, and a certain thickness is required. However, by providing the narrowing means, the thickness can be reduced.

Further, since the display is not seen through the microprism, a thin front light type illuminating device can be provided in which the display is not whitened. Also,
Since a large-area microprism over the entire display section is not required, a large display section can be constructed relatively inexpensively, and even if an LED is used as a light source, uniform surface illumination can be achieved. When used as a lighting device, the thickness of the entire portable information device can be reduced.

The surface of the transparent substrate facing the display section is provided so that the gap between the display section and the display section becomes narrower in accordance with the distance from the light source. Near light can be reflected, lighting efficiency improves,
Lighting can be brightened. Also, since the light guide section is an air layer, light incident on the reflective color display panel for illumination is refracted within 42 degrees from the vertical and transmitted through the color filter due to the difference in refractive index. There is no problem that light is absorbed and the display becomes dark.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A front light type illuminating device according to the present invention has a predetermined gap between a light source and a display unit to be illuminated, and a transparent substrate disposed at a position facing the display unit. Narrowing means for narrowing an incident angle of light from a light source in a thickness direction of the gap and guiding the light to the gap.

Further, the narrowing means is made of a transparent member having a microprism on the surface corresponding to the transparent substrate and / or the surface corresponding to the display unit to be illuminated. Alternatively, the surface on the side corresponding to the transparent substrate and / or the surface on the side corresponding to the display unit to be illuminated is a microprism-shaped reflecting plate.

Alternatively, the narrowing means is made of a transparent member having an inclined prism on a surface corresponding to the transparent substrate and / or a surface corresponding to the display unit to be illuminated. Alternatively, the narrowing means includes an inclined reflecting plate disposed on a surface corresponding to the transparent substrate and / or a surface corresponding to the display unit to be illuminated.

Further, the light source includes a light emitting portion, and a light guide having a light control layer that scatters or diffuses the light irradiated from the light emitting portion from the side. Alternatively, a surface of the transparent substrate facing the display unit is provided so that a gap between the transparent substrate and the display unit is reduced according to a distance from the light source.
Further, the display device of the present invention includes a reflective color liquid crystal panel having a reflective layer, a liquid crystal layer, and a color filter, and a transparent substrate disposed to face the front surface of the panel with a predetermined gap therebetween.
A light source for irradiating light and a narrowing means for narrowing an incident angle of the light from the light source in a thickness direction of the gap and guiding the incident angle to the gap are provided.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. (Embodiment 1) An embodiment of the present invention is shown in FIG. FIG. 1 (a)
1 is a schematic diagram showing a cross-sectional structure, and FIG. 1B is a schematic diagram showing a planar structure. A plurality of chip types L constituting a light source
In front of the ED 1, a micro-prism collimator 2 constituting a narrowing means is provided. The collimator 2 is made of a light-guiding material, and has microprisms 2a on the upper side and the lower side. As shown in the figure, the microprism 2a is provided with a plurality of prisms having an inclination angle of about 5 to 15 degrees in a length direction thereof, and a reflective color liquid crystal panel 4 constituting a display unit. And transparent substrate 3
The incident angle of the irradiation light of the LED 1 in the thickness direction of the gap 3a is narrowed down to the gap 3a between the LED 3 and the LED 3 to guide the light. Therefore, the reflection of the light from the LED 1 by the transparent substrate 3 is increased by the narrowing of the light, and the light leaking from the transparent substrate 3 to the outside is reduced. Light traveling in the opposite direction to the display surface is also a transparent substrate 3.
The ratio of light reflected from the LED 1 increases, and the light from the LED 1 reaches far. Therefore, even if the illumination is provided at a position that is not so high (not far away) from the reflective color liquid crystal panel, it is possible to sufficiently illuminate the entire screen, and it is possible to achieve a reduction in thickness by lowering the illumination position. In particular, if a micro-prism collimator is used as the narrowing-down means as in this example, the collimator can be made smaller, so that the thickness can be further reduced. For example, when used as a lighting device for a portable information device, the entire portable information device can be made thinner. LED
A reflection layer 5 as shown in the figure is provided around 1 and the collimator 2 to prevent the light from the LED 1 from leaking out of places other than the transparent substrate 3. Therefore, lighting efficiency is improved. Although the LEDs 1 are arranged on the opposing surfaces, it is more effective to arrange them at positions where they do not oppose each other as shown in FIG. 1B, and illumination with uniform brightness can be performed. In addition, the reflection type color liquid crystal panel 4
Has a configuration (not shown) in which a reflective layer and a color filter are formed on the inner surfaces of two electrode substrates sandwiching a liquid crystal layer.

Next, the principle of illumination will be described. Chip type LED
The light emitted from 1 is narrowed down by the collimator 2 in the thickness direction of the gap 3a. Most of the light that is directed to the transparent substrate 3 without going to the reflective color liquid crystal panel 4 is reflected by the transparent substrate 3 and illuminates the reflective color liquid crystal panel 4 even in a portion far from the light source. be able to. The light reflected by the transparent substrate 3 travels to the reflective color liquid crystal panel 4 together with the light directed to the reflective color liquid crystal panel 4 in the light narrowed down by the collimator 2. Among these lights, the light that is refracted and transmitted by the reflective color liquid crystal panel 4 is the air within the gap 3 a and the reflective color liquid crystal panel 4.
Is refracted within 42 degrees from the vertical direction of the reflective color liquid crystal panel 4 and passes through the color filters in the reflective color liquid crystal panel 4 due to the difference in the refractive index from the transparent substrate. Therefore, there is no problem that light is excessively absorbed by the color filter and the display becomes dark. Thus, the reflective color liquid crystal panel 4 is illuminated.

Therefore, it is not necessary to provide a microprism on the display screen as in the related art, and the display does not appear white, so that the display quality can be improved and the cost can be reduced as compared with the related art. Since there is no need to provide a microprism, uniform surface illumination can be achieved even if an LED is used as the light source.

Since the transparent substrate is not directional, light sources can be provided on all sides of the illuminating device so that a very bright display can be obtained. Further, depending on the required brightness of the illumination, the LED 1 may be provided on only one surface. The microprism 2a provided in the microprism collimator 2 may be provided only on the upper side in the drawing or only on the lower side in the drawing.

The micro-prism collimator 2 may be provided for each light source only in a portion corresponding to the light emitting portion. In this case, the weight associated with the micro-prism collimator 2 can be reduced, so that the weight can be reduced. (Examples 2, 3, and 4) Another example of the narrowing-down means shown in Example 1 is shown in FIGS. In these drawings, the same reference numerals as those in FIG. 1 denote the same components.

FIG. 2 shows an example in which a micro prism mirror 6 is used as a narrowing means. As shown in the figure, a plurality of reflective prisms having an inclination angle of about 20 degrees in the length direction are provided continuously on the upper side and the lower side in the drawing. Note that one side may be a plane mirror. FIG. 3 shows an example in which the inclined prism 7 is used as the narrowing means. It is desirable that the tilt angle of the tilt prism 7 be set to about 10 degrees.

FIG. 4 shows an example in which the inclined reflecting plate 8 is used as the narrowing means. It is desirable to set the inclination angle of the inclined reflection plate 8 to about 20 degrees. Fifth Embodiment FIG. 5 shows an example in which the light guide 9 is used as the light source shown in the first embodiment. The light guide 9 is made of an acrylic rod having a light guiding property, and the chip type LED 1 is provided on the side surfaces 9a and 9b.
D1 irradiation light is incident. The light guide 9 has an LED
A light control layer 9c for irradiating the gap 3a with the incident light from the light source 1 substantially uniformly is provided. The light control layer 9c
, A scattering surface or a diffusion surface formed by applying a white paint is used. As a result, the same effect as described above can be obtained, and uniform illumination can be achieved with a small number of LEDs.
Note that a narrowing-down means for narrowing the diffused light from the light control layer 9C in the thickness direction may be integrally formed on the upper surface and the lower surface of the light guide 9, and in this case, holding of each part becomes easy.

(Embodiment 6) FIG. 6 shows the surface of the transparent substrate 3 facing the display unit 4 shown in the first embodiment in which the gap 3a between the display unit 4 and the light source 1 is reduced according to the distance from the light source 1. It was done. By configuring the transparent substrate 3 in this manner, among the light from the narrowed down light source, light that is nearly horizontal to the display surface can be reflected as illumination light, so that the illumination efficiency is improved and the same light source is used. In this case, the lighting can be brightened.

In the first to sixth embodiments, the light source is not limited to the LED, but may be a fluorescent tube or EL. In addition, the transparent substrate may also serve as a part of a component of the touch panel type input device. In this case, the entire thickness including the touch panel type input device can be reduced, the configuration can be simplified, and the cost can be reduced.

Also, the transparent substrate may be configured to also serve as the transparent opening of the case of the portable device, whereby the overall thickness can be reduced, the configuration can be simplified, and the cost can be reduced. Further, a second transparent substrate may be newly provided between the transparent substrate and the display unit. In this case, the light from the light source may be irradiated between the transparent substrates. Further, as a reflection type color liquid crystal panel constituting a display unit, any type in which a reflection layer and a color filter are formed inside two electrode substrates sandwiching a liquid crystal layer can be applied. In addition to the scattering mode liquid crystal display device and the phase transition type or λ / 4 plate type guest host mode liquid crystal display device, a single-polarizer type TN, S using one polarizer
It can be applied to various display modes such as TN and R-OCB.

The display section is not limited to a reflective color liquid crystal panel, but may be a poster or the like.

[0026]

According to the present invention, of the light incident on the gap from the light source, most of the light traveling in the direction opposite to the display surface is reflected by the transparent substrate, and the reflected light is used as illumination light. Therefore, it is possible to uniformly illuminate a portion remote from the light source. Further, since the angle of incidence of the light from the light source in the thickness direction of the gap is narrowed by the narrowing means, most of the light from the light source traveling in the direction opposite to the display surface can be reflected by the transparent substrate. In addition, light reaches far away from the light source, and the illumination efficiency is further increased, and uniform bright illumination can be achieved. Further, when there is no narrowing means, it is necessary to install the illumination at a high position in order to uniformly illuminate the entire screen, and a certain thickness is required. However, by providing the narrowing means, the thickness can be reduced.

Further, since the display is not viewed through the microprism, a thin front-light type illuminating device with high display quality and no white display can be provided. In addition, since a large-area microprism over the entire display unit is not provided, even a large display unit can be made relatively inexpensive, and even if an LED is used as a light source, uniform surface illumination can be achieved. When used as a lighting device for a device, the thickness of the entire portable information device can be reduced.

The surface of the transparent substrate facing the display section is provided so that the gap between the display section and the display section becomes narrower in accordance with the distance from the light source. Near light can be reflected, lighting efficiency improves,
If the same light source is used, the lighting can be brightened. Also, since the light guide section is an air layer, light incident on the reflective color display panel for illumination is refracted within 42 degrees from the vertical and transmitted through the color filter due to the difference in refractive index. There is no problem that light is absorbed and the display becomes dark.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing another example of the narrowing-down unit of FIG. 1;

FIG. 3 is an explanatory view showing another example of the narrowing-down means of FIG. 1;

FIG. 4 is an explanatory diagram showing another example of the narrowing-down means of FIG. 1;

FIG. 5 is an explanatory view showing another example of the light source of FIG. 1;

FIG. 6 is an explanatory view showing another example of the transparent substrate of FIG. 1;

FIG. 7 is an explanatory view showing a conventional lighting unit.

[Explanation of symbols]

 Reference Signs List 1 light source 2 narrowing means 3 transparent substrate 3a gap 4 display unit, reflective color liquid crystal panel 6 narrowing means 7 narrowing means 8 narrowing means 9 light guide 9a light control layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI G09F 9/00 336 G09F 9/00 336B (72) Inventor Kaoru Takano 1-8 Nakase Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Instruments Inc. Within the Company (72) Inventor Shigeru Chimmatsu Matsu 1-8-8 Nakase, Mihama-ku, Chiba City, Chiba Prefecture Inside Seiko Instruments Inc. (72) Inventor Teruo Ebihara 1-8-8 Nakase, Mihama-ku, Chiba City, Chiba Prefecture Seiko Instruments Inc. (72) Inventor Hiroshi Sakuma 1-8-8 Nakase, Mihama-ku, Chiba City, Chiba Prefecture Inside Seiko Instruments Inc. (72) Inventor Takakazu Fukuchi 1-8-8 Nakase, Mihama-ku, Chiba City, Chiba Prefecture Seiko Instruments Inc. ( 72) Inventor Osamu Yamazaki Naka, Mihama-ku, Chiba-shi, Chiba 1-8-8 Se, Seiko Instruments Co., Ltd. (72) Inventor Naoshi Shino 1-8-8 Se, Nakahama, Mihama-ku, Chiba Chiba Prefecture Inside 72 Seiko Instruments, Inc. (72) Inventor Masafumi Hoshino 1, Nakase, Mihama-ku, Chiba 8-8 Seiko Instruments Co., Ltd. (72) Inventor Shuhei Yamamoto 1-8 Nakase, Mihama-ku, Chiba-shi, Chiba SII IRD Center Co., Ltd.

Claims (8)

[Claims] A transparent substrate disposed at a position facing a display unit having a predetermined gap between a light source for irradiating light and a display unit to be illuminated; A narrowing means for narrowing an incident angle of light from the light source and guiding the light to the gap. 2. The method according to claim 1, wherein the narrowing means is formed of a transparent member having a microprism on a surface corresponding to the transparent substrate and / or a surface corresponding to the display unit to be illuminated. Item 2. A front light type lighting device according to Item 1. 3. The method according to claim 1, wherein the narrowing means has a microprism-shaped reflector on a surface corresponding to the transparent substrate and / or a surface corresponding to the display unit to be illuminated. 2. The front light type lighting device according to 1. 4. A method according to claim 1, wherein said narrowing means comprises a transparent member having an inclined prism on a surface corresponding to said transparent substrate and / or a surface corresponding to said display unit to be illuminated. Item 2. A front light type lighting device according to Item 1. 5. The apparatus according to claim 1, wherein the narrowing means has an inclined reflector on a surface corresponding to the transparent substrate and / or a surface corresponding to the display unit to be illuminated. Front light type lighting device. 6. The light source according to claim 1, wherein the light source includes a light emitting unit, and a light guide having a light control layer that scatters or diffuses the light irradiated from the light emitting unit from a side surface. 2. The front light type lighting device according to 1. 7. The display device according to claim 1, wherein a surface of the transparent substrate facing the display unit is provided such that a gap between the transparent substrate and the display unit is reduced according to a distance from the light source. Front light type lighting device. 8. A reflective color liquid crystal panel having a reflective layer, a liquid crystal layer, and a color filter, a transparent substrate opposed to a front surface of the panel with a predetermined gap, a light source for emitting light, and the light source. A narrowing means for narrowing an incident angle of the light from the gap in a thickness direction of the gap and guiding the light to the gap.