JP2002109938A - Lighting device and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device and a display device enabled to prevent a position shift between a line-shaped light guide body making a point light source diffused into line shape, and a light guide body making the linearly diffused light diffuse into plane shape. SOLUTION: The lighting device and display device comprise a line-shaped light guide body 32 integrally formed with a light guide plate 4 so that a line- shaped light source 3 faces one side surface of a light guide plate along almost whole longitudinal part of it through an air layer 5, and a point light source 31 making light get into one side surface of the line-shaped light guide body 32. As the light guide plate 4 and the line-shaped light guide body 32 are formed integrally, any position shift does not occurs between them, and as the line- shaped light guide body 32 and the air layer 5 are made to contact with each other, the light of the point light source 31 does not directly diffuse in the light guide plate 4, but get into the light guide plate 4 after being diffused linearly.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to a lighting device for illuminating a display screen of a non-light emitting type display means, and a display device provided with the lighting device.

[0002]

2. Description of the Related Art In recent years, techniques for reducing the weight, size, and power consumption of electronic devices have been remarkably developed. In the course of this technique, non-light emitting display means represented by liquid crystal display means have been developed. It is noteworthy that the use of the electronic device reduces the weight, size, and power consumption of the electronic device.

There are two types of liquid crystal display devices: a transmission type and a reflection type. The transmission type liquid crystal display device is provided with an illuminating device for illuminating the liquid crystal display means from behind, a so-called backlight. Is provided with a lighting device for illuminating the liquid crystal display means from the front side, a so-called front light.

[0004] These illuminators include a linear light source and a light guide plate which receives light from the linear light source from one end surface and distributes and emits the light from one of the front and back surfaces in a planar manner (particularly). JP-A-10-153777, JP-A-10-31
No. 1915).

For example, as schematically shown in the cross-sectional view of FIG. 5, an illuminating device 52 is arranged as a front light on the surface side of a reflection type liquid crystal display means 51.
Is provided with a linear light source 53, a light guide plate 54, and an antireflection film 55 provided on the back surface of the light guide plate 54 so as to oppose the liquid crystal display means 51 to enhance visibility.

Some of the linear light sources 53 use a linear light emitting tube, a light emitting diode array, or the like. In order to reduce power consumption, for example, as shown in FIG. A light source including a light guide 61 and a linear or rod-shaped light guide 62 that receives light from the point light source 61 at one end thereof, and scatters and emits the light linearly is often used. Further, if necessary, as shown in FIG. 5, the linear light source 53 has a reflector 6 for directing the emitted light to one end surface of the light guide plate 54.
3 are provided.

On the surface of the light guide plate 54, a reflecting surface 56 for dispersing light incident on one end surface of the light guide plate 54 from the linear light source 53, that is, the light incident surface a and reflecting the light to the back surface side,
The light reflected by the light guide plate 54 and incident on the back surface of the light guide plate 54 is
The light-transmitting surfaces 57 for transmitting light to the front surface side of No. 4 are alternately formed.

The reflecting surface 56 is, for example, 43 ° with respect to a horizontal plane so as to face the incident surface a on which the light of the linear light source 51 is incident.
The light transmitting surface 57 is inclined, for example, by 2 ° with respect to the horizontal plane so as to face the end surface b opposite to the incident surface a. Therefore, in plan view, the reflecting surface 56 and the light transmitting surface 5
In this case, the area ratio to 7 is about 1:27. Note that the depth of the valley between the reflection surface 56 and the light transmission surface 57 or the height of the ridge between the light transmission surface 57 and the reflection surface 56 is formed uniformly over the entire surface of the light guide plate 54.

[0009]

In this display device, when the positional relationship between the linear light guide and the light guide plate is shifted, light does not sufficiently enter a part of the light guide plate, and the liquid crystal display is not displayed. A dark area where sufficient light is not applied to the means 51 occurs,
Part of the light emitted from the light guide 62 leaks without being incident on the light guide plate 54, or scattered light is directly emitted from the point light source 61.
And a bright line may appear.

Therefore, an attempt was made to prevent the displacement between the linear light guide and the light guide plate by integrally forming the linear light guide and the light guide plate. Light incident on one end of the body diffuses directly into the light guide plate and does not reach the opposite end of the linear light guide sufficiently. It turned out that bright lines and bright spots were concentrated, making it impractical.

In view of such circumstances, the present invention provides an illuminating device in which a positional shift between a linear light guide and a light guide plate does not occur, and by using this illuminating device,
It is an object of the present invention to provide a display device capable of performing high-quality display on average over the entire surface.

[0012]

According to the illumination device of the present invention, a linear light source and light from the linear light source are incident on an incident surface having one end surface, and are dispersed and emitted in a plane from the exit surface. In a lighting device including a light guide plate, the linear light source is formed integrally with the light guide plate so as to substantially face one end surface of the light guide plate via an air layer over substantially the entire length thereof, and The linear light guide is provided with a point light source for entering a light beam at one end or both ends.

According to this, since the linear light guide is formed integrally with the light guide plate, the positional relationship between the linear light guide and the light guide plate does not shift.

Further, since an air layer is interposed between the linear light guide and the light guide plate over substantially the entire length of the linear light guide, light incident from one end of the linear light guide is linearly guided. The light can be reflected on the emission surface of the body and reach the other end side in an averagely dispersed manner, and the light dispersed on average from the linear light guide can be incident on one end surface of the light guide plate, The occurrence of dark areas, bright lines, bright areas, etc. can be prevented.

As a method for integrally forming the linear light guide and the light guide plate, a known method such as, for example, integral molding or integral injection molding may be employed. What is necessary is just to form using.

In the present invention, if the one end surface of the light guide plate, that is, the incident surface on which the light emitted from the linear light guide enters, is formed as a rough surface, the light incident on this incident surface is Since the light having the scattering property and the average viewing angle characteristic is incident on the light guide plate, the light emitted from the light guide plate is more evenly dispersed in a plane, and the uniformity of the image quality can be improved.

Next, a display device according to the present invention includes the illumination device according to the present invention and a non-light-emitting type display means disposed on an emission surface side of the illumination device in order to achieve the above object.

According to this, the illumination device according to the present invention makes it possible to irradiate the light uniformly distributed over the entire display screen of the non-light emitting type display means, so that there is no dark part, bright line, bright part, etc. Image display.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A lighting device and a display device according to an embodiment of the present invention will be specifically described with reference to the drawings.

As shown schematically in the cross-sectional view of FIG. 2, a display device according to an embodiment of the present invention includes a non-light-emitting type display means 1 comprising a well-known reflective liquid crystal display means and a non-light-emitting type display means. The display screen side of the means 1, that is, the front side (FIG.
The illumination device 2 according to an embodiment of the present invention is disposed at the upper side (upper side in FIG. 2).

As schematically shown in the plan view of FIG. 1, the illuminating device 2 includes a light guide plate 4 covering the entire surface of the non-light emitting type display means 1, and an incident surface formed by one end surface of the light guide plate 4. And a linear light source 3 for receiving light over the entire length of the light guide plate 41. The linear light source 3 is formed integrally with the light guide plate so as to face one end surface of the light guide plate 4 via the air layer 5 over substantially the entire length thereof. Linear light guide 32, and one point light source 31, for example, L, which enters a light beam at one end of the linear light guide.
Equipped with ED.

The linear light guide 32 and the light guide plate 4 are a resin molded product obtained by integrally molding a translucent thermoplastic resin such as an acrylic resin or a polycarbonate resin by injection molding. It is formed by punching.

A point light source 3 is provided at one end of the linear light guide 32.
A light source fitting hole 33 for inserting and positioning one end portion is formed, and a light beam is incident from a point light source 31 on an incident surface 34 formed on the bottom surface of the light source fitting hole 33. The light incident on the surface is reflected by the adjustment of the refractive index of the peripheral surface in contact with the air, and travels toward the opposite end surface 35.

Surface 3 of linear light guide 32 opposite to light guide plate 4
6 is a reflecting surface 3 inclined toward the incident surface 34.
7 are formed at predetermined intervals,
Light that has entered the reflecting surface 37 while traveling from the incident surface 34 to the opposite end surface 35 is reflected by the reflecting surface 37 and exits toward the light guide plate 4.

For example, the reflecting surfaces 37 are arranged at equal intervals in the axial direction of the linear light guide 32, and the pitch depth of the reflecting surfaces 37 is made equal or the pitch depth of the reflecting surfaces 37 is reduced. If the amount of light reflected from each reflecting surface 37 is made equal by changing the pitch at a constant value, light that is uniformly dispersed over the entire length of the linear light guide 32 is transmitted from the linear light guide 32 to the light guide plate 4. Can be incident.

Of the light that strikes the reflection surface 37 and travels toward the light guide plate 4, the light that enters the emission surface 39 at an angle smaller than the critical angle passes through the air layer 5 with refraction, and further enters the light guide plate 4. The light enters the surface 41.

Since the linear light guide 32 and the light guide plate 4 are integrally formed by integral injection molding as described above, the assembling work of the lighting device 2 is simplified, and the linear light guide is formed. There is no danger that the positional relationship between the light guide plate 32 and the light guide plate 4 will be deviated, and light that is linearly dispersed on the light guide plate 4 from substantially the entire length of the linear light guide 32 can be made incident. Therefore, there is no possibility that the light guide plate 4 has a dark portion where the light amount is insufficient, or a bright line or a bright portion where the light amount is excessive.

As shown in FIG. 2, the back surface 42 of the light guide plate 4 is formed to be flat, and the end surface 4 on the opposite side from the entrance surface 41 is formed.
3, it is formed so as to approach the surface 44. Also, the surface 44 of the light guide plate 4 has a reflecting surface 45 inclined at an angle of, for example, 43 ° with respect to a horizontal plane toward the incident surface 41, and an inclined surface at an angle of, for example, 2 ° with respect to the opposite end surface. The light transmitting surfaces 46 are alternately formed.

Here, the reflection surfaces 45 and the light transmission surface 4
6 are arranged in parallel with each other, and the length of each reflecting surface 45 in the flow direction is made equal, so that the reflecting surfaces 45 are arranged at equal intervals and parallel in plan view. In this case, the reflection surface 45 and the light transmission surface 4
The ratio of the plane projection area to 6 is 1:27.

Further, as shown in FIG.
A top line (crest line) and a valley line (valley line) at which each reflecting surface 45 and the light transmitting surface 46 intersect with each other are inclined with respect to the incident surface 41 so that moire is not generated in a display image.

Further, as shown in FIG. 2, the back surface 42 of the light guide plate 4 is formed in a mirror surface in the same manner as a conventional light guide plate, and a known antireflection film 6 is laminated thereon to enhance visibility.

Therefore, a part of the light incident from the incident surface 41 is reflected by the reflection surface 45 and exits to the non-light-emitting type display means 1 side, and the light reflected by the non-light-emitting type display means 1 is transmitted through the back surface 42. The light passes through the surface 46 and is emitted to the surface of the light guide plate 4.

In this embodiment, the point light source 31
Is provided at one end of the linear light guide 32, but the linear light guide 3
A pair of point light sources 31 made of, for example, LEDs may be arranged at both ends of the pair 2 so as to face each other.

In this embodiment, the linear light source 3
Although the reflection plate 7 is provided to make the light incident on the light guide plate 4 without waste, the reflection plate 7 may be omitted.

In the lighting device according to another embodiment of the present invention shown in the plan view of FIG. 3, a reflection groove 38 is formed on the upper surface of the linear light guide 32. The cross-sectional shape of the reflection groove 38 is not particularly limited, and may be, for example, a square, an isosceles trapezoid, a one-way triangle,
A cross-sectional shape such as a U-shape or a V-shape can be adopted.

In this embodiment, the reflecting film 8 is attached to the end face 35 opposite to the incident face 34, and the light reaching the end face 35 is reflected to increase the amount of light emitted from the linear light guide 32. I try to make it.

Further, in this embodiment, the socket 9 into which the point light source 31 is inserted is protruded, and the linear light guide 3 is formed by the socket 9 and the rib 10 provided over the side surface 47 of the light guide plate 4.
The connecting portion between the light guide plate 2 and the light guide plate 4 is reinforced.

Other configurations, operations, and effects of this embodiment are the same as those of the previous example, and thus detailed description thereof will be omitted.

A lighting device according to still another embodiment of the present invention shown in the plan view of FIG. 4 has reflecting grooves 38 formed on both upper and lower surfaces of a linear light guide 32, and is provided at both ends of the linear light guide 32. A point light source 31 composed of an LED is inserted into each of the protruding sockets 9 so that light beams are incident on both ends of the linear light guide 32 from the two point light sources 31. Other configurations, operations, and effects are the same as those of the embodiment shown in FIG. 3, and a detailed description thereof will be omitted to avoid duplication.

In these embodiments, the light incident surface 41 of the light guide plate 4 is formed as a flat surface. However, the light incident surface 41 is formed with fine irregularities by die-cutting, spray painting, embossing, or the like. The light emitted from the light guide plate 4 can be more uniformly dispersed by diffusing the light incident on the light guide plate 4 and averaging the viewing angle characteristics. .

In each of the above embodiments, the illumination device 2 is used as a front light. However, these illumination devices 2 can be used as a backlight.

[0042]

As described above, in the lighting device of the present invention, the linear light source is formed integrally with the light guide plate so as to substantially face the one end face of the light guide plate via the air layer over the entire length thereof. The linear light guide, and one or a pair of point light sources that make light incident on one or both ends of the linear light guide, the positional relationship between the linear light guide and the light guide plate is incorrect. And the light emitted from the point light source can be evenly and linearly dispersed by the linear light guide, and can be evenly and uniformly dispersed by the light guide plate. And even surface illumination without dark spots, bright lines, bright spots, etc. due to the displacement of the light guide plate.

Further, since the number of parts is reduced and the assembling is simplified, the assembling cost can be reduced.

Next, since the display device according to the present invention uses the lighting device of the present invention, the display screen is evenly illuminated by the lighting device of the present invention over the entire surface, and the brightness of dark spots, bright lines, bright spots, and the like. An image with uniform image quality and uniformity can be displayed.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a display device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing a display device according to one embodiment of the present invention.

FIG. 3 is a front view schematically showing a lighting device according to another embodiment of the present invention.

FIG. 4 is a front view schematically showing a lighting device according to still another embodiment of the present invention.

FIG. 5 is a cross-sectional view schematically showing a conventional example.

FIG. 6 is a plan view schematically showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Non-luminous display means 3 Linear light source 4 Light guide plate 5 Air layer 31 Point light source 32 Linear light guide 41 Incident surface

Claims (3)

[Claims] 1. An illuminating device comprising: a linear light source; and a light guide plate which receives light from the linear light source from an incident surface having one end surface, and emits the light by dispersing the light planarly from an emission surface. A light source is a linear light guide integrally formed with the light guide plate so as to face one end surface of the light guide plate through the air layer over substantially the entire length thereof, and a light beam is applied to one or both ends of the linear light guide. An illumination device comprising a point light source for incidence. 2. The lighting device according to claim 1, wherein the one end surface of the light guide plate is formed as a rough surface. 3. A display device, comprising: the illumination device according to claim 1; and a non-light-emitting display unit disposed on an emission surface side of the light guide plate.