JPH09311333A - Illuminator for reflection type display and reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illuminator for a reflection type display whose structure is simple and the distortion of an image is avoided, and a reflection type liquid crystal display device whose power consumption is low, and is easily make a color device and which can be used in a dark place. SOLUTION: This illuminator 5 is equipped with a plate-like light transmission plate 1, a light source 2 provided at the end face of the plate 1 and a high molecular film 4 stuck to one surface of the plate 1, and scattering and transmitting only incident light in a specified angle range and straight-advancing and transmitting the incident light in the other angle range; and the reflection type liquid crystal display device is composed by providing a reflection type liquid crystal panel 6 whose liquid crystal display surface is brought into contact with the surface of the high molecular film 4 side of the illuminator 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device for a reflective display such as a liquid crystal panel or a printed matter, and a reflective liquid crystal display device using the illuminating device.

[0002]

2. Description of the Related Art Liquid crystal display devices are thin and light, and are therefore widely used as displays for portable information terminals. The liquid crystal is a light-receiving element that does not emit light by itself, and includes a reflective type in which a reflector is placed on the back surface to illuminate with external light to see a display, and a transmissive type in which a backlight is placed on the back surface.

Since the liquid crystal can be driven by a low voltage of several volts, the reflective liquid crystal element has extremely low power consumption, but it cannot be used in a dark environment, and the color liquid crystal panel using a color filter has a low light utilization rate. The reflective type has the drawback that bright colors cannot be displayed. As a reflection type liquid crystal panel lighting, in wristwatches, a miniature ball lamp is placed diagonally in front of the panel and used as night lighting.
Since it lacks uniformity, it is limited to small LCD panels.

As a solution to this problem, a method has been proposed in which a flat plate-shaped illumination (front light) is attached to the front of a reflective liquid crystal panel to share the ambient light with the front light (for example, SID '95). Digest, pages 375 to 378, CYTai, H.Zou, PKTai
). FIG. 3 shows a block diagram of the illumination of Tai et al. In FIG. 3, 30 is a transparent plastic (usually having a refractive index of 1.5).
A front and rear) light guide plate, 31 is a fluorescent light source provided on the end surface of the light guide plate 30, and 32 is an optical compensation plate provided on the front surface of the light guide plate 30. FIG. 4 shows an enlarged view of the IV portion of FIG.
A prism portion 33 is formed on the front surface of the light guide plate 30.

As shown in FIG. 5, the light 35 emitted from the fluorescent lamp light source 31 is totally reflected by the surface of the wedge-shaped collimating portion 34 of the light guide plate 30 (the critical angle of the total reflection angle is 42 degrees). The light is incident on the plane of the light guide plate 30 at a shallow angle (10 degrees). Then, as shown in FIG. 6, a part of the incident light 36 is generated by the light guide plate 3.
The light is reflected by the inclined surface of the prism portion 33 of 0, exits the light guide plate 30, and illuminates the display surface (not shown) provided on the back surface of the light guide plate 30. Further, the light 37 reflected by the flat surface portion of the light guide plate 30 further penetrates deep inside the light guide plate 30.

Although transparent flat plate illumination is realized in this way, the image on the display is distorted due to the presence of the prism portion 33. Therefore, in order to correct this, the optical compensation plate 32 is used.
Is carried.

[0007]

In the case of a reflection type liquid crystal panel only for external illumination, it has a drawback that it is difficult to colorize and cannot be used in a dark place, and the transmission type liquid crystal panel has a drawback that it consumes a large amount of power. there were. Also, FIG.
In the case of the front light illumination, the prism portion 33 must be provided on the front surface of the light guide plate 30 or the optical compensation plate 32 must be placed, and the structure is complicated.
There is a problem that it is difficult to completely remove the distortion of the image caused by.

Therefore, an object of the present invention is to provide an illuminating device for a reflection type display which has a simple structure and does not cause image distortion, and a reflection type liquid crystal display device which consumes little power and is easy to colorize and can be used even in a dark place. Is.

[0009]

According to another aspect of the present invention, there is provided a lighting device for a reflection type display, comprising: a flat light guide plate; a light source provided on an end face of the light guide plate; And a polymer film that scatters and transmits only the incident light in the range and transmits the incident light in the other angle ranges in a straight line.

According to a second aspect of the present invention, there is provided a reflective display illuminating device according to the first aspect, wherein the specific angle range is 42 degrees in a direction approaching the light source with the observer direction being 0 degree in the normal direction of the light guide plate. To 55 degrees. The illuminating device for a reflective display according to claim 1 or 2 has a simple structure in which a polymer film is simply attached to one surface of a light guide plate having a light source on an end face. Further, when the light incident on the reflection type display is scattered and reflected by the reflection type display and returns to the front viewer, the polymer film and the light guide plate are transparent, so that the image on the display can be seen without distortion or blurring.

According to a third aspect of the present invention, there is provided a lighting device for a reflective display according to the first or second aspect, wherein the polymer film is partially attached to the light guide plate, and the area of the attached portion is increased as the distance from the light source increases. It is characterized by that. According to the illuminating device of the reflective display of the third aspect, in addition to the operation of the first or second aspect, uniform illumination can be performed even when the area of the light guide plate is large.

According to a fourth aspect of the present invention, in the reflective liquid crystal display device, the liquid crystal display surface is brought into contact with the polymer film side surface of the illuminating device of the first or second or third reflective display. And a reflective liquid crystal panel is provided. According to the reflection type liquid crystal display device of the fourth aspect, since it is illuminated by both the environmental lighting and the lighting device, a bright display can be obtained and the power consumption is small.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a perspective view of a reflective liquid crystal display device including a reflective display illumination device 5 and a reflective liquid crystal panel 6 provided on one surface thereof. First, the fluorescent light source 2 is placed on the end face of the acrylic light guide plate 1 having a thickness of 6 cm × 8 cm × 3 mm, the fluorescent light source 2 is wound with the sheet material 3 having the silver reflection film formed on the inner surface, and the end is placed on the light guide plate 1. Glue into a wedge shape. The polymer film 4 is attached to the back side of the light guide plate 1 as viewed by the observer of the display. The light guide plate 1, the fluorescent light source 2, the sheet material 3, and the polymer film 4 constitute a lighting device 5 for a reflective display.

By the way, as the polymer film 4, for example, Lumisty (registered trademark) manufactured by Sumitomo Chemical Co., Ltd. is used. Lumisty is a polymer film having a diffraction grating-like fine structure, and FIG. 2 is a functional explanatory diagram of Lumisty. Light incident from the front of the Lumisty as shown in FIG. 2 (a) travels straight, and light incident from an angle of 20 to 50 degrees is scattered and transmitted as shown in FIG. 2 (b), and is incident at a shallower angle. The light goes straight as shown in FIG. The angle range of the incident angle that scatters and transmits can be changed depending on the manufacturing method, and several types are on the market, which are intended to be used in the fields of construction and decoration such as blinds and lighting covers.

The Lumisty used in this embodiment, as shown in FIG. 1, has a viewing direction (arrow 15) of 0 ° in the normal direction of the light guide plate, and 25 ° to 55 ° in the direction approaching the light source. The incident light of a certain degree is scattered and transmitted, and the incident light of other angle ranges is transmitted straight. The light emitted from the light source 2 is reflected by the sheet material 3, enters the light guide plate 1 at a shallow incident angle, and is totally reflected at the interface between the light guide plate 1 and the air. In the case of acrylic, the critical angle of total internal reflection is about 42 degrees, so from 42 degrees to 5
The light totally reflected at 5 degrees is scattered and transmitted like the light ray 13 when passing through the polymer film 4, so that it is emitted from the light guide plate 1 to the display surface and illuminates the display.

In FIG. 1, a liquid crystal panel 6 is provided on the surface of the illuminating device 5 of the reflective display on the side of the polymer film 4, with the liquid crystal display surface in contact with the surface of the polymer film 4. There is. The liquid crystal panel 6 has a glass substrate 7
The liquid crystal 8 is sandwiched between them, the glass substrate 7 is sandwiched between the polarizing plate 9 and the aluminum scattering reflection plate 10, and the image is written by being driven by the drive circuit 12 via the electrode 11 on the inner surface of the glass substrate 7. The light ray 13 incident on the liquid crystal panel 6 is reflected by the scattering reflection plate 10 and passes through the polarizing plate 9 again in the return path to form an image.

Light such as the light ray 14 which is totally reflected at an incident angle larger than 55 degrees goes straight through the polymer film 4, but is incident on the liquid crystal panel 6 at a distance from the light source 2 and is scattered and reflected. The light scattered and reflected in the front direction at 10 reaches the observer. According to the illuminating device 5 of the reflection type display thus configured, the polymer film 4 is simply attached to one surface of the light guide plate 1 having the light source 2 on the end face.
Thin lighting for reflective displays can be realized with a simple structure.

The light 13 incident on the liquid crystal panel 6 is
When returning to the front direction, which is the viewing angle of the observer after being reflected by the scattering reflector 10, the polymer film 4 and the light guide plate 1 are transparent, so that the image on the display can be seen without distortion or blurring. Further, since both the environmental lighting and the lighting device 5 of the reflection type display are used for illumination, the reflection type liquid crystal display device in which the reflection type liquid crystal panel 6 and the lighting device 5 are combined is very low in power and bright in display. Is obtained, and it is easy to colorize and can be used even in dark places.

In the above embodiment, the polymer film 4 was attached to the entire surface of the light guide plate 1. However, when the light guide plate 1 has a large area and the brightness is distributed, the polymer film 4 is used. It is possible to eliminate unevenness in brightness by partially attaching and adjusting the distribution. For example, in a light guide plate 1 having a size of 15 cm × 20 cm, polymer films 4 cut into stripes having a width of 2 mm are attached at intervals, the attachment pitch is 10 mm near the light source, and 4 at the farthest place.
Gradually changing the pitch to mm, it became possible to achieve fairly uniform illumination.

Further, in the above-described embodiment, since the existing Lumisty is used for the polymer film 4, the incident light of 25 to 55 degrees is scattered, but since the total reflection angle is 42 degrees, at least the angle of total reflection is 42 degrees. Any light control function that scatters and transmits an incident angle of 42 to 55 degrees may be used. Further, in the above-described embodiment, the liquid crystal panel 6 is used as the reflective display, but the reflective display illumination device 5 of the present invention is also applicable to a reflective display having a scattering reflective surface, such as a printed matter. Has the effect of.

[0021]

According to the illuminating device of the reflection type display according to claim 1 or 2, since the polymer film is simply attached to one surface of the light guide plate having the light source on the end face,
Thin lighting for reflective displays can be realized with a simple structure. Further, when the light incident on the reflection type display is scattered and reflected by the reflection type display and returns to the front viewer, the polymer film and the light guide plate are transparent, so that the image on the display can be seen without distortion or blurring.

According to the illuminating device of the reflection type display of claim 3, in addition to the effect of claim 1 or claim 2,
Even when the area of the light guide plate is large, uniform illumination can be performed. According to the reflection type liquid crystal display device of the fourth aspect, since it is illuminated by both the environmental illumination and the illumination device, a bright display can be obtained, and colorization is easy and it can be used even in a dark place. Also, it consumes less power.

[Brief description of drawings]

FIG. 1 is a perspective view of a reflective liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a functional explanatory view of a transmission / scattering polymer film.

FIG. 3 is a perspective view of a conventional reflective display illumination device.

FIG. 4 is an enlarged perspective view of an IV portion of FIG.

FIG. 5 is a diagram showing a path of light in a collimating portion of a conventional light guide plate.

FIG. 6 is a diagram showing a path of light in a plane portion of a light guide plate of a conventional example.

[Explanation of symbols]

 1 Light Guide Plate 2 Fluorescent Lamp Light Source 3 Sheet Material 4 Polymer Film (Lumisty) 5 Illumination Device for Reflective Display 6 Liquid Crystal Panel (Reflective Display) 7 Glass Substrate 8 Liquid Crystal 9 Polarizing Plate 10 Scattering Reflector 11 Electrode 12 Driving Circuit 13,14 rays

Claims (4)

[Claims] 1. A flat light guide plate, a light source provided on an end face of the light guide plate, and a light source plate attached to one surface of the light guide plate to scatter and transmit only incident light in a specific angle range and to make incident light in another angle range. An illumination device for a reflective display that includes a polymer film that allows light to pass straight through. 2. The reflective display according to claim 1, wherein the specific angle range includes a range of 42 degrees to 55 degrees in a direction approaching the light source, with the observer direction being 0 degree in the normal direction of the light guide plate. Lighting equipment. 3. The illumination of the reflective display according to claim 1, wherein the polymer film is partially adhered to the light guide plate, and the area of the adhered portion is increased as the distance from the light source increases. apparatus. 4. The method according to claim 1, 2 or 3.
A reflection type liquid crystal display device, comprising a reflection type liquid crystal panel provided on the surface of the illumination device of the reflection type display on the side of the polymer film, the liquid crystal display surface being in contact therewith.