JPH0621884B2 - Liquid crystal display lighting device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a lighting device for a liquid crystal display element, which is arranged on the back surface side of the liquid crystal display element and irradiates the liquid crystal display element with light.

[Conventional technology]

In a display device using a liquid crystal display element, an illuminating device is arranged on the back surface side of the liquid crystal display element, the liquid crystal display element is irradiated with light by the illuminating device, and the characters passing by the light passing through the liquid crystal display element are displayed. Some are configured to display numbers and the like.

FIG. 8 is a diagram showing a schematic structure of a display device using such a conventional liquid crystal display element. As shown in the figure, the lighting device 101 is provided on the back side of the liquid crystal display element (LCD) 103.
Are arranged to illuminate the liquid crystal display element 103 from the back surface side. The illumination device 101 of the liquid crystal display element has a case 101a having a predetermined length in the vertical direction, and a color filter 101b attached to the open upper surface of the case 101a.
A lamp 101c is inserted on the bottom surface of a.
Reference numeral 103a denotes a terminal for supporting the liquid crystal display element 103 and energizing the liquid crystal display element 103,
Reference numeral 105 denotes a frame of the display device, 107 denotes a transparent protective cover for protecting the liquid crystal display element 103, and 1
Reference numeral 09 denotes a substrate that supports the lighting device 101 and mounts various electronic components.

FIG. 9 is a diagram showing another conventional illumination device for a liquid crystal display element. As shown in the figure, the illuminating device 102 has a case 102a made of a thin plate-shaped milky white resin, and holes of a predetermined shape are formed on the upper surface of the case 102a. Light emitting diodes 102b are arranged on both side surfaces of the hole in the longitudinal direction. The entire structure is filled with the transparent resin 102c. In this illuminating device 102, the light emitted from the light emitting diode 102b is diffusely reflected in the transparent resin 102c filled in the hole, so that the entire surface of the transparent resin 102c can be illuminated.

[Problems to be solved by the invention]

However, in the conventional illumination device 101 for a liquid crystal display element shown in FIG. 8, in order to make the entire surface of the color filter 101b uniformly illuminate, it is necessary to increase the distance between the lamp 101c and the color filter 101b. There is a problem in that the size of the device in the thickness direction must be considerably increased.

On the other hand, a conventional liquid crystal display device illumination device 102 shown in FIG.
Is made up of a thin plate-shaped case 102a, the vertical dimension of the lighting device can be reduced. However, a small amount of light emitted from the light emitting diode 102b is directed in the upper direction, that is, toward the liquid crystal display element side. Therefore, the lighting device 102
However, there is a problem that the light for illuminating the liquid crystal display element (not shown) arranged on the upper surface side is insufficient.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a thin liquid crystal display device illuminating device capable of uniformly and sufficiently illuminating the entire surface of a color filter.

[Means for solving problems]

In order to solve the above problems, the present invention provides a liquid crystal display element illumination device which is disposed on the back surface side of a liquid crystal display element and irradiates the liquid crystal display element with light. The thickness of the light guide is gradually increased, and then the thickness of the light guide is reduced. The light emitting element insertion hole is provided in the thickness direction at or near the thickest part of the substantially V-shaped inclined surface, and each inclination of the bottom surface and the light guide except the entire side surface inside the light emitting element insertion hole. The entire surface and the entire outer peripheral side surface are covered with a non-translucent member that reflects light, the light emitting element is housed in the light emitting element insertion hole so that substantially the entire light emitting element is inserted, and the light emitted from the light emitting element is received. Guide the light into the light guide only from the side of the light emitting element insertion hole. And configured to direct the liquid crystal display element side is reflected by the inclined surfaces and the outer peripheral side surface of the light guide body is.

[Action]

If the lighting device of the liquid crystal display element is configured as described above, the light emitted from the light emitting element does not directly illuminate the liquid crystal display element but indirectly illuminates the liquid crystal display element by reflection, so that the vertical dimension of the lighting device can be considerably reduced. Further, since the reflected light is directed to the liquid crystal display element, the entire surface of the liquid crystal display element can be uniformly and sufficiently illuminated.

〔Example〕

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of an embodiment of an illuminating device for a liquid crystal display element according to the present invention.

In FIG. 1, a lighting device 100 for a liquid crystal display element is inserted into a plate-shaped light guide 1 made of a transparent material and light emitting element insertion holes 1a, 1a formed near both sides of the back surface of the light guide 1. The light emitting elements 5 and 5 are provided, and the light 50 emitted from the light emitting elements 5 and 5 is formed on the back surface of the light guide body 1b (the side close to the light emitting elements 5 and 5 is directed downward). The light 50 is reflected by (tilted) and guided to the upper side (the liquid crystal display element (not shown) side), and the light guide 50 is made to glare by covering the surface side of the light guide 1 with the color filter 3. Is configured.

Hereinafter, each component of this embodiment will be described in detail.

2A and 2B are views showing the light guide 1 of the present embodiment. FIG. 2A is a plan view and FIG. 2B is a sectional view taken along the line AA of FIG.

In the figure, the light guide 1 is composed of a rectangular plate made of transparent synthetic resin. On the surface of the light guide body 1, the surface of the light guide body 1 and the color filter 3 described below are provided.
A concave portion 1c is provided between the concave portion 1c and the concave portion 1c, and a peripheral edge 1d around which the color filter 3 described below is attached is formed around the concave portion 1c. A pair of light emitting element insertion holes 1a, 1a for inserting the light emitting elements 5 and 5 described below into the light guide body 1 are formed near both sides of the back surface of the light guide body 1, and the length of the back surface of the light guide body 1 is long. Slopes 1b, 1b are formed symmetrically from the central portion in the direction toward the light emitting element insertion holes 1a, 1a. The inclined surface 1b is thin at the central portion of the light guide 1 and becomes thicker toward the light emitting element insertion holes 1a, 1a, and further, the light emitting element insertion holes 1a, 1a.
It is inclined so that it becomes thinner from the outside. That is, the shapes of the inclined surfaces 1b, 1b are substantially W-shaped (two sets of V-shaped) as a whole, and the light-emitting element insertion holes 1a,
1a is provided near the two thickest portions on the back surface of the light guide 1. Protrusions 1e and 1e for fixing the light guide 1 to a substrate (described below) are formed on both sides of the light emitting element insertion holes 1a and 1a.

Next, a method of attaching various members to the light guide 1 will be described.

First, as shown in FIG. 3, a reflection member 7 for reflecting the light 50 emitted by the pair of light emitting elements 5, 5 is provided on the entire surface of the inclined surface 1b between the both light emitting element insertion holes 1a, 1a on the back surface of the light guide 1. Install. The reflecting member 7 is made of a silver film that reflects light, and is attached to the entire surface of the inclined surface 1b with a transparent adhesive.

Next, an opaque paint 1f that reflects light is applied to the entire back surface and the entire side surface of the light guide body 1 including the entire back surface of the reflecting member 7. At this time, the paint 1f is also applied to the inside of the light emitting element insertion holes 1a, 1a. The paint 1f uses, for example, white paint.

Next, a reamer is passed through the light emitting element insertion holes 1a and 1a to remove only the paint 1f applied to the side surfaces 1a-1 and 1a-1 of the light emitting element insertion holes 1a and 1a.
A reflection film 9 is formed on the bottom surface of 1a.

Next, on the peripheral edge 1d formed on the upper surface of the light guide 1, the light guide 1
A rectangular color filter 3 is attached to cover the entire upper surface of the. The material of the color filter 3 is a filter which diffuses upward light from the light guide 1 and diffuses it in a specular manner.

As shown in FIG. 1, the light emitting elements 5 and 5 are inserted into the light emitting element insertion holes 1a and 1a of the light guide 1 to which various members are attached in this manner, and the lighting device for the liquid crystal display element according to this embodiment. 100 is completed. The light guide 1 has protrusions 1e and 1e.
Substrate 13 (shown in FIG. 4) by heat staking
And the terminals of the light emitting elements 5 and 5 are also attached to the substrate 13.
Mounted on.

Next, the arrangement position of the illumination device 100 of this liquid crystal display element is shown in FIG. As shown in the figure, the liquid crystal display element 11 is arranged under the window 15 a of the case 15, and the lighting device 100 fixed on the substrate 13 is arranged on the back surface of the liquid crystal display element 11. Reference numeral 17 is a transparent protective cover of the liquid crystal display element 11, and 19 is an electrostatic sheet attached on the protective cover 17.

Next, the operation of the illumination device 100 of this liquid crystal display element will be described.

As shown in FIG. 1, the light emitting element insertion hole 1a of the light guide 1,
The light emitting elements 5 and 5 inserted in 1a are caused to emit light. Here, since the upper surfaces of the light emitting element insertion holes 1a, 1a are covered with the coating material 1f, the light 50 emitted from the light emitting elements 5, 5 does not go directly upward, and the side surface 1 of the light emitting element insertion holes 1a, 1a.
The light is introduced into the light guide 1 from a-1, 1a-1.

The lateral light 50 introduced into the light guide 1 is reflected by the inclined surface 1b formed on the back surface of the light guide 1 and becomes light 50 directed upward. Further, the light 50 directed to the side surface of the light guide 1 is also reflected and becomes the light 50 in the upward direction. At this time, the paint 1f is applied to all the back surfaces and the side surfaces of the light guide body 1, and the reflection member 7 is attached to the back surface of the light guide body 1, so that the reflection of the light 50 by the inclined surface 1b is further improved. It will be good.

In this way, the light 50 emitted from the light emitting elements 5 and 5 is not directly directed to the color filter 3, but the light 50 reflected in various directions by the inclined surface 1b of the light guide 1 is directed to the color filter 3. The entire color filter 3 can be illuminated uniformly.

FIG. 5 is a view showing another embodiment of the liquid crystal display illuminating device according to the present invention, FIG. 6 is a view showing a case 21 used in this embodiment, and FIG. The same figure (b) is a cross-sectional arrow view on the BB line of the same figure (a).

The light guide 1 in this embodiment is the same as the light guide 1 shown in FIG. 2, but the structure of covering the back surface and the side surface is different. That is, in this embodiment, instead of coating the light guide body 1, the back surface and the side surface of the light guide body 1 are covered with an opaque case 21 that reflects light. As shown in FIG. 6, the case 21 is configured to be in close contact with the light guide 1 and cover the entire back surface and side surfaces of the light guide 1, and the light emitting elements 5, 5 are provided near both ends in the longitudinal direction thereof. And holes 21a for inserting the protrusions 1e of the light guide 1 are formed.

Next, a method of assembling the liquid crystal display illuminating device in this embodiment will be described.

First, the reflection paper 23 is attached to the upper surfaces of the light emitting element insertion holes 1a, 1a of the light guide 1. The reflection paper 23 is formed of a non-translucent material that reflects light.

Next, the case 21 is fitted from the back side of the light guide 1, and the color filter 3 similar to that shown in FIG. Next, insert the light emitting elements 5 and 5 shown in FIG. 1 into the light emitting element insertion holes 1a and 1a of the light guide 1.
After arranging, the illumination device for the liquid crystal display element is completed. If the back side of the light guide 1 is covered with the case 21 and the reflection paper 23 as in the present embodiment, the assembling work becomes easier as compared with the case where the back side of the light guide 1 is painted.

FIG. 7 is a side sectional view showing still another embodiment of the illumination device for the liquid crystal display device according to the present invention.

The illuminating device for a liquid crystal display element in this embodiment is a transparent and flat light guide 1'and a light emitting element 5'inserted in a light emitting element insertion hole 1a 'formed in the center of the back surface of the light guide 1'.
And a light 50 'emitted from the light emitting element 5'is reflected by an inclined surface 1'b formed on the back surface of the light guide 1'to the upper side (liquid crystal display element (not shown) side). At the same time as guiding, the surface side of the light guide 1'is a flat plate type color filter 3 '.
It is configured so that the light 50 'can be illuminated in a glare state by being covered with. Here, 1'f is paint and 7'is a reflecting member.

If the illuminating device for the liquid crystal display element is configured in this way, it is possible to uniformly illuminate the entire color filter 3 '(and thus the entire liquid crystal display element) with only one light emitting element 5'.

Although the embodiment of the illumination device for the liquid crystal display element according to the present invention has been described in detail above, the present invention is not limited to this, and for example, even if the inclined surface 1b of the light guide body 1 is subjected to a satin treatment. Well, if configured in this way, the light emitted from the light emitting element 5 is diffused more effectively by the inclined surface 1 to illuminate the color filter 3 in a glare state, and the surface of the light guide body 1 is subjected to a satin finish. With such a configuration, the light guided from the light guide 1 to the liquid crystal display element side is more effectively diffusedly reflected, and the color filter 3 is illuminated in a glare-like manner. The light 50 is directed to the color filter 3 side by applying paint 1f (Fig. 1) or reflecting paper 23 (Fig. 5) on the bottom surface of the light emitting element insertion holes 1a, 1a provided in the light guide 1. Not configured, but instead of these A large number of irregularities may be provided on the upper surfaces of the light emitting element insertion holes 1a, 1a so as to diffuse the light 50 directed to this surface, and the color filter 3 need not be a chromatic filter. Various modifications such as a milky white color and other colors are possible.

〔The invention's effect〕

As described above in detail, according to the lighting device of the liquid crystal display element of the present invention, the light emitted from the light emitting element is introduced into the light guide body only from the side surface of the light emitting element insertion hole to thereby provide the back surface of the light guide body. The light emitted from the light emitting element does not directly illuminate the liquid crystal display element, but the reflected light indirectly illuminates the liquid crystal display element. It has an excellent effect that the size of the device in the vertical direction can be considerably reduced and the entire surface of the liquid crystal display device can be uniformly illuminated.

Particularly in the case of the present invention, since the light emitting element insertion hole is provided in the inclined surface of the back surface of the light guide and the light emitting element is inserted therein, for example, the light emitting elements are arranged on both side surfaces in the longitudinal direction of the light guide. Compared with the case, the distance until the light emitted from the light emitting element is reflected inside the light guide body and reaches the light guide body surface does not differ much depending on the location of the light guide body surface. Since the light source is close to each place, it is possible to illuminate the light guide surface with strong and uniform light without loss.

Further, in the case of the present invention, the light emitting element insertion hole is provided in the thickest part (or in the vicinity) of the V-shaped (W-shaped in the case of two sets) inclined surface on the back surface of the light guide. Since the light emitting element is housed in such a manner that almost the entire light emitting element is inserted therein, even if the light emitted from the light emitting element is light that is directed obliquely downward from the light emitting element, the light emitted from the light emitting element is inclined around the light emitting element. The surface can be reflected upward and guided to the upper surface of the light guide.
That is, most of the light emitted from the light emitting element is guided to the surface of the light guide body, and the light loss is small.

Since the light loss is small from the above two points, the number of light emitting elements used in this lighting device can be reduced.

Further, in the case of the present invention, a light emitting element insertion hole is provided on the back surface of the light guide body, the light emitting element is inserted into the hole, and the bottom surface of the light emitting element insertion hole is covered with a non-translucent member that reflects light. Since the entire side surface of the element insertion hole was not covered with the member, the light emitted upward from the light emitting element was reflected from the opaque member on the bottom surface of the light emitting element insertion hole and then from the side surface of the light emitting element insertion hole. Light introduced into the light guide body and emitted laterally (including obliquely upward and downward directions) from the light emitting element is directly introduced into the light guide body from the side surface of the light emitting element insertion hole. That is, the light emitted upward from the light emitting element is not directly guided to the light guide surface, but is reflected and then guided to the light guide surface, so that the light illuminating the light guide surface becomes more uniform.

Further, in the case of the present invention, since the light emitting element is arranged on the back surface of the light guide, the area of this illuminating device (the surface area when this illuminating device is viewed from above) can be reduced, and the size can be reduced. In the lighting device shown in FIG. 9, since the light emitting diodes 102b are arranged on both side surfaces of the lighting device 102, the surface area of the lighting device cannot be reduced accordingly.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of an illuminating device for a liquid crystal display device according to the present invention, and FIG. 2 is a view showing a light guide 1 of this embodiment.
The figure (a) is a top view, the figure (b) is AA of the figure (a).
FIG. 3 is a diagram for explaining a method of attaching various members to the light guide body 1, FIG. 4 is a diagram showing an arrangement position of a lighting device of a liquid crystal display element, and FIG. 5 is the present invention. FIG. 6 is a view showing another embodiment of the illuminating device for the liquid crystal display element according to FIG. 6, FIG. 6 is a view showing the case 21, FIG. 6A is a plan view, and FIG. 6B is B of FIG. FIG. 7 is a side sectional view showing still another embodiment of the liquid crystal display element illuminating device according to the present invention, and FIG. 8 is a view showing a conventional liquid crystal display element illuminating device, FIG. 9 is a diagram showing another conventional illumination device for a liquid crystal display element. In the figure, 1 ... Light guide, 1a ... Light emitting element insertion hole, 1b ...
… Sloping surface, 1f …… Paint, 3 …… Color filter, 5
...... Light emitting element, 7 ... Reflecting member, 11 ... Liquid crystal display element, 21 ... Case.

Claims (1)

[Claims] 1. A lighting device for a liquid crystal display element, which is arranged on the back surface side of a liquid crystal display element and irradiates the liquid crystal display element with light, wherein the shape of the back surface is made of a transparent plate material and its thickness is gradually increased. Next, at least one set is provided in which the thickness is gradually reduced to form a substantially V-shaped inclined surface that is convex downward as a whole. A light emitting element insertion hole is provided in the thickness direction of the V-shape or in the vicinity thereof in the thickness direction, and the bottom surface except the entire side surface inside the light emitting element insertion hole, the entire inclined surface of the light guide, and the entire outer peripheral side surface. Is covered with a non-translucent member that reflects light, the light emitting element is housed in the light emitting element insertion hole so that substantially the entire light emitting element is inserted, and the light emitted from the light emitting element is inserted into the side surface of the light emitting element insertion hole. Introduced into the light guide from only each tilt of the light guide The liquid crystal display lighting device element characterized by the is reflected by the outer peripheral side guided to the liquid crystal display element side.