JP2002072899A - Liquid crystal display device and portable terminal - Google Patents

Abstract

(57) [Summary] (with correction) [PROBLEMS] To provide a thin display device having a lighting function, which has high contrast and high visibility both when the lighting device is turned on and when it is not turned on. SOLUTION: A thin illuminating device is arranged in front of a display 2 and a reflector 3 is arranged on the back of the display 2. The lighting device includes a light guide 11 and a light source 12 disposed on an end face side of the light guide 11, and a light output side surface 14 of the light guide 11 has a light output side plane, and the light output side plane. And a concave-convex shape formed by a plane in a direction parallel to the plane and a plane in a direction perpendicular to the light-emitting side plane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a display device such as a liquid crystal display device having an illumination function.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display device having an illumination function is, as shown in FIG.
A lighting device 1 having a planar shape is arranged on the back of the device, and the lighting device is usually used with lighting always turned on, or as shown in FIG. The reflection sheet 4 is arranged so that it can be used for both lighting and non-lighting.

[0003]

However, such a conventional liquid crystal display device having an illuminating function is illuminated when the illumination is constantly turned on, and when a semi-transmissive and semi-reflective sheet that consumes a large amount of power is used. There is a problem that the display is dark and the contrast is low both when the device is turned on and when the device is not turned on.

In order to solve such a conventional problem, the present invention arranges a lighting device in front of a display such as a liquid crystal display so that the lighting device can be turned on and off when it is turned on. It is an object of the present invention to provide a display device having high contrast and high visibility.

[0005]

In order to solve the above-mentioned problems, a display device according to the present invention is characterized in that it has an illuminated body which is a display body and a lighting device arranged on the upper surface thereof.

That is, the display device of the present invention comprises:
It has a transparent light guide and a light source disposed on the end face side of the light guide, and one surface of the light guide has a light-emitting side plane, a surface parallel to the light-emitting side plane, and An uneven shape formed by the light-emitting side plane and a surface in a vertical direction is provided, and a light beam from the light source propagates through the light guide and exits from the uneven shape portion to form the illumination target. The body is illuminated, and is emitted through the light guide.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the entire display device of the present invention, and an illumination device 1 is arranged on a front surface of a liquid crystal display 2. A reflection plate 3 is arranged on the back of the liquid crystal display 2 to constitute a reflection type liquid crystal display. The lighting device 1 is a liquid crystal display 2
It has a function of projecting a light beam on the side and transmitting the light beam reflected by the reflector 3 with little dispersion. This is effective when the illuminating device 1 is turned off when there is sufficient external light, and in this case, the illuminating device 1 acts as a mere transparent plate to reduce the visibility and not to affect the display quality. is there. When used in a dark place where external light is not sufficient, the lighting device 1 illuminates the liquid crystal display 2 and the light reflected by the reflector 3 is converted into a mere transparent plate in the same manner as when the lighting device 1 is turned off. Since it functions and transmits as it is, it is effective to maintain high visibility.

In a transmission type liquid crystal display device in which the illumination device 1 is disposed on the back of the liquid crystal display 2, a light beam from the illumination device 1 transmits through the liquid crystal display 2 only once to generate a contrast between a bright portion and a dark portion. In contrast, the lighting device 1 according to the present invention
Is disposed on the front surface of the liquid crystal display 2, the light from the illuminating device 1 passes through the liquid crystal display 2 once, is reflected by the reflector, and transmits again.
This is effective for obtaining higher visibility by increasing the contrast.

FIG. 2A shows an embodiment for realizing the above-described lighting device. A light source 12 is arranged on at least one end face side of the light guide 11. The light guide 11 is shown in FIG.
As shown in (b), a projection 13 on the rib is provided on one surface of the transparent plate substantially in parallel with the light source 2, and each surface of the projection 13 is substantially parallel to a surface substantially parallel to the light emitting side plane 14. It is composed only of various surfaces. That is, on the light-emitting side surface of the light guide 11,
A light-emitting side plane 14, a surface parallel to the light-emitting side plane 14,
The light emitting side flat surface 14 and the surface in the vertical direction form an uneven shape. The light guide 11 is formed of a transparent material having a refractive index of 1.4 or more. The light beam from the light source 12 is a light beam 16
a and light rays 16 b, after being incident from the end face 15, total reflection is repeatedly performed in the light guide 11 and emitted only from the side surfaces of the projections 13, so that more light is emitted from the back surface of the lighting device 1, Can be illuminated.

The transparent material forming the light guide 11 is a transparent resin such as acrylic resin or polycarbonate resin, an inorganic transparent material such as glass, or a composite thereof.
It is formed by a method such as injection molding, photo-curing resin, etching, bonding of a film on a transparent resin or glass flat slope.

As shown in FIG. 3A, the light beam incident from the end face 15 has an optical axis of 45 degrees or less due to refraction with respect to the axis of the light guide 11 in the long side direction. In order to achieve this, a height higher than the width of the projection 13 is required. In the case below that, the light beam is emitted to the upper surface of the illuminating device 1 through the path as shown in FIG. However, when the value greatly exceeds 対, not only is optically meaningless, but also a problem arises that production becomes difficult. As described above, it is desirable that the ratio of the width to the height of the projection 13 is exactly about the same.

Since the visible light has a wavelength of about 380 nm to 700 nm, the width of the projection 13 and the height of the projection 13 need to be about 5 μm or more to prevent a spectral stripe pattern from being generated by interference due to diffraction. Since the size of the pixel of the liquid crystal display is 200 μm to 300 μm, the size should be 100 μm or less in order to prevent the occurrence of a stripe pattern due to interference with the pixel. In addition to the above, the size of the projection 13 is about 10 for convenience in manufacturing.
It is desirable that the thickness be in the range of at least 50 μm. By adjusting the density of the projections 13 on the light guide 11, uniformity of the irradiation luminance can be improved. Actually, the projections 13 are arranged sparsely in the vicinity of the light source 12, and are arranged densely continuously as the projections 13 are separated. In this case, a method of changing the density by keeping the size of the projection 13 constant, a method of changing the size by keeping the density constant, a method of changing both, and the like are adopted.

FIG. 4A shows another embodiment. Protrusion 13
The same effect as that of the rib can be obtained also when the is formed in a prismatic shape. The side surface of the projection 13 perpendicular to the light source 12 is irradiated with the light beam at a critical angle or more, and is totally reflected and has no relation to the emitted light. When a prism having a square bottom is formed on a substantially rectangular light guide 11 as shown in FIG. 4B, a light source 12 is arranged on two adjacent sides, and a light beam incident from the two sides is projected 13 Light can be emitted from each side of

FIG. 5A shows another embodiment in which the projections 13 are formed in a columnar shape. The light beam irradiated to the cylindrical surface of the projection 13 at a critical angle or less emits light, and the light beam irradiated at the critical angle or more repeats reflection at the cylindrical surface, then inverts at the bottom surface of the protrusion 13 and further reflects at the cylindrical surface. Repeatedly follow the path that travels through the light guide again. Light rays emitted from the cylindrical surface are different from those in the case of the prism shown in FIG.
As shown in (b), the irradiation range can be widened.

[0015]

According to the present invention, as described above,
When the display device is used, for example, for a liquid crystal display portable computer terminal, the display quality is not degraded even when used by turning off the lighting in a bright place to save power, and a display with high contrast can be performed even when the display device is turned on. be able to.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing another embodiment of the present invention.

FIG. 3 is a diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing another embodiment of the present invention.

FIG. 5 is a diagram showing another embodiment of the present invention.

FIG. 6 is a diagram showing a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Illumination device 2 Liquid crystal display body 3 Reflector 11 Light guide 12 Light source 13 Projection 14 Light emission side plane 15 End face 16 Light ray

[Procedure amendment]

[Submission date] July 25, 2001 (2001.7.2)
5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Name of invention

[Correction method] Change

[Correction contents]

Patent application title: Liquid crystal display device and portable terminal

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

[0005]

According to the present invention, there is provided a liquid crystal display device comprising: a liquid crystal display; and a lighting device disposed in front of the liquid crystal display. A transparent light guide, and a light source disposed on an end face side of the light guide, and a surface of the light guide on a liquid crystal display side has a light emitting side plane, a surface parallel to the light emitting side plane. , And an uneven shape formed by the light emitting side plane and the surface in the vertical direction are provided, and the light guide transmits external light to the liquid crystal display side when the light source is turned off, The light reflected on the liquid crystal display side is transmitted.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction contents]

[0006] A portable terminal according to the present invention is a portable terminal provided with a liquid crystal display device, wherein the liquid crystal display device has a liquid crystal display and a lighting device arranged in front of the liquid crystal display. The lighting device has a transparent light guide, and a light source disposed on an end face side of the light guide, and a light emitting side plane is provided on a surface of the light guide on a liquid crystal display side, A surface in a direction parallel to the light-emitting side plane, and a concavo-convex shape formed by a surface in a direction perpendicular to the light-emitting side plane are provided, and the light guide includes an external light source when the light source is turned off. Is transmitted to the liquid crystal display side, and light reflected on the liquid crystal display side is transmitted.

Claims (1)

[Claims] 1. A display device for illuminating an object to be illuminated, wherein the display device includes an object to be illuminated, a transparent light guide, and a light source disposed on an end face side of the light guide. A light emitting side plane, a surface in a direction parallel to the light emitting side plane, and an uneven shape formed by a surface in a direction perpendicular to the light emitting side plane are provided on one surface of the light guide, A display device, wherein a light beam propagates through the light guide, emits from the uneven portion, illuminates the illuminated body, and is emitted through the light guide. .