JP3021881U - Surface emitting device - Google Patents

Abstract

(57) [Summary] [Object] To provide a surface emitting device capable of uniformly emitting light on the surface of a light guide plate. [Structure] A linear light source 2 is arranged on one end face of a transparent light guide plate 1, an end face reflection plate is arranged on the other end face opposite to each other, a light diffusion transmission part is formed on the back surface of the light guide plate 1, and a surface on which the light diffusion transmission part is formed. In the surface emitting device, the back reflector is arranged on the light guide plate 1, the diffusion sheet is arranged on the surface of the light guide plate 1, and the light source reflector is arranged so as to cover the surface of the linear light source 2 opposite to the light guide plate 1.
The area ratio of the light diffusion / transmission part in the vicinity 4a of the light guide plate side surface perpendicular to the tube axis of the linear light source 2 increases while increasing the rate of change as it approaches the side surface of the light guide plate 1 in the direction parallel to the tube axis of the linear light source 2, In particular, the change is greatest near the center of the side surface of the light guide plate 1, and the starting point where the area ratio of the light diffusion / transmission part starts to change draws an arc with the side surface of the light guide plate 1 inside.

Description

[Detailed description of the device]

[0001]

[Technology field to which the device belongs]

 The present invention relates to a thin surface illumination device used for a thin illuminated light as a display, and a thin and lightweight laptop computer, word processor, liquid crystal TV, backlight for car navigation and the like.

[0002]

[Prior art]

 Conventionally, the linear light source 2 is arranged on one end face of the transparent light guide plate 1, and the end face reflection plate 3 is arranged on the other end face opposite to each other, and the light diffusion transmission part 4 is formed on the back surface of the light guide plate 1, and the light diffusion transmission part 4 is formed. An edge in which the rear surface reflection plate 5 is arranged on the formed surface, the diffusion sheet 6 is arranged on the surface of the light guide plate 1, and the light source reflection plate 7 is arranged so as to cover the surface of the linear light source 2 opposite to the light guide plate 1. There was a light type surface emitting device (see FIG. 1). As the light diffusion / transmission part 4, for example, the area ratio increases from the line light source 2 side of the light guide plate 1 to the specific position as the distance from the line light source 2 increases, and from the specific position to the end face reflection plate 3. Some of them are formed in a gradation pattern such that the above is constant (see FIG. 5).

[0003]

[Problems to be solved by the device]

 However, the light reflection on the side of the light guide plate perpendicular to the tube axis of the linear light source is weaker than the light reflection on the end surface of the light guide plate facing the tube axis of the line light source. Alternatively, the amount of light emitted by total reflection is small, and the brightness is significantly reduced near the side surface of the light guide plate that is perpendicular to the tube axis of the linear light source, especially near the center of the side surface of the light guide plate, making it difficult to obtain uniform brightness. .

Accordingly, the present invention provides a surface emitting device capable of improving the brightness of the surface of the light guide plate in the vicinity of the side surface of the light guide plate that is perpendicular to the tube axis of the linear light source and uniformly emitting light on the surface of the light guide plate. The purpose is to

[0005]

[Means for Solving the Problems]

 In order to achieve the above object, the present invention has a transparent light guide plate having a linear light source on one end face and an end face reflection plate on the other end face facing the transparent light guide plate, and a light diffusion / transmission part formed on the back surface of the light guide plate. The back reflector is placed on the surface where the light diffusion / transmission part is formed, the diffusion sheet is placed on the surface of the light guide plate, and the light source reflector is placed so as to cover the surface of the linear light source opposite to the light guide plate. In the surface emitting device, the area ratio of the light diffusion / transmission part near the side surface of the light guide plate that is perpendicular to the tube axis of the linear light source increases while increasing the rate of change as it approaches the side surface of the light guide plate in the direction parallel to the tube axis of the linear light source. Especially, the change is largest near the center of the side surface of the light guide plate, and the starting point where the area ratio of the light diffusion / transmission part begins to change is configured to draw an arc with the side surface of the light guide plate inside.

Further, in the above structure, an inclined surface portion is formed on the back surface side of the light guide plate such that the thickness thereof becomes thinner as the distance from the linear light source increases, and a light diffusion / transmission portion is formed on the back surface of the light guide plate including the inclined surface portion and the end surface. In the direction parallel to the tube axis of the linear light source, the area ratio of the light diffusion / transmission part at the corner of the light guide plate on the reflector side increases with increasing rate of change as it approaches the side surface of the light guide plate. In the direction perpendicular to, the rate of change increases as it gets closer to the end face reflection plate, and the starting point of the change of the area ratio of the light diffusing / transmitting part is an arc with the light guide plate corner part inside. Good.

[0007]

[Embodiment of device]

 Hereinafter, the surface emitting device of the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing an embodiment of a surface emitting device, FIG. 2 is a schematic view showing an area ratio change of a light diffusion / transmission part in an embodiment of a surface emitting device according to the present invention, and FIG. FIG. 4 is a schematic view showing the area ratio change of the light diffusion / transmission part in another embodiment of the surface emitting device according to the present invention, and FIG. 4 is a sectional view showing another embodiment of the surface emitting device. Reference numeral 1 is a light guide plate, 2 is a linear light source, 3 is an end face reflection plate, 4 is a light diffusion / transmission part, 4a is near the side face of the light guide plate, 4b is a corner part of the light guide plate, 5 is a back face reflection plate, 6 is a diffusion sheet, and 7 is Light source reflectors are shown respectively.

In the surface emitting device of the present invention, the linear light source 2 is disposed on one end face of the transparent light guide plate 1, the end face reflection plate 3 is disposed on the opposite other end face thereof, and the light diffusion / transmission part 4 is formed on the rear face of the light guide plate 1. Then, the back reflector 5 is arranged on the surface on which the light diffusion / transmission part 4 is formed, and the diffusion sheet 6 is arranged on the surface of the light guide plate 1 so as to cover the surface of the linear light source 2 on the opposite side to the light guide plate 1. A light source reflection plate 7 is arranged (see FIG. 1).

As the light guide plate 1, a rectangular plate material having a thickness of about 1.5 to 30 mm is preferable. As the material of the light guide plate 1, resin such as acrylic, polycarbonate, polystyrene, acrylic styrene, polyvinyl chloride, or the like, or glass can be used. Moreover, it is preferable that all the side surfaces of the light guide plate 1 are finished to be smooth.

As the line light source 2, a cathode ray tube such as a hot cathode ray tube or a cold cathode ray tube having a diameter of 2 to 3 mm is used.

The end face reflection plate 3 reflects the light that has exited from the other end face of the light guide plate 1 and has not returned to the light guide plate 1 side so that the light can be used efficiently. As the material of the end face reflection plate 3, for example, the following materials are preferable. (1) A film or plate in which a white pigment is mixed in a resin. (2) White painted or white printed aluminum plate. (3) A metal plate having a mirror surface, a metal foil such as aluminum, or a film or plate obtained by depositing a metal such as aluminum or silver. Further, when the end face reflection plate 3 is arranged as a reflection layer which is in direct contact with the other end face of the light guide plate 1, there is the following method. That is, white coating or printing may be directly applied to the other end surface of the light guide plate 1, or vapor deposition may be directly applied to the other end surface of the light guide plate 1. The inner surface of the case that houses the light guide plate 1 and the linear light source 2 may be painted or printed in white to form the end face reflection plate 3.

The light diffusion / transmission part 4 scatters and reflects the light guided from the linear light source 2 into the light guide plate 1, and directs a part of the light toward the front surface side of the light guide plate 1. The light is evenly distributed by changing the area ratio of.

The basic change in the area ratio of the light diffusion / transmission part 4 is that the area ratio increases as the distance from the line light source 2 of the light guide plate 1 increases, or the line ratio increases from the line light source 2 side of the light guide plate 1 to a specific position. The area ratio increases as the distance from the light source 2 increases, and the area ratio becomes constant or decreases from the specific position to the end face reflection plate 3. The feature of the present invention is that a further change in the area ratio is added to the light diffusion / transmission part 4 in the vicinity 4a of the side surface of the light guide plate which is perpendicular to the tube axis of the linear light source 2 (see FIG. 2). That is, in the direction parallel to the tube axis of the linear light source 2, the rate of change is increased as it approaches the side surface of the light guide plate, and the change is maximized particularly near the center of the side surface of the light guide plate, and the area of the light diffusion / transmission part 4 is increased. The starting point where the rate begins to change is an arc with the side of the light guide plate as the inside.

In order to change the area ratio of the light diffusing and transmitting portion 4, the light diffusing and transmitting portion 4 is formed by a dot having an arbitrary shape, and the size of the dot is changed or the number of dots is changed depending on the position. . The shape of the dot is not particularly limited, and may be any shape such as round dot, square dot, chain dot. Further, instead of the dots, the stripe shape may be formed. As a method of forming the light diffusing and transmitting portion 4, there are a printing method such as screen printing using a matte ink, a transfer method, and a method in which the back surface of the light guide plate 1 is made uneven. As the matte ink, an ink containing a particulate transparent substance such as calcium carbonate or silica having a refractive index substantially equal to or less than that of the light guide plate 1 can be used to further improve the light diffusivity.

The back reflector 5 reflects light that could not be returned into the light guide plate 1 in the light scattering reflector 4 to the light guide plate 1 side so that the light can be used efficiently. As the material of the back reflector 5, for example, the same materials (1) to (3) as those for the end reflector 3 are preferable. Further, the inner surface of the case that houses the light guide plate 1 and the linear light source 2 may be painted or printed in white to form the back reflector 5.

The diffusion sheet 6 is for diffusing light emitted from the surface of the light guide plate 1 to smooth the luminance distribution. For example, the following materials are preferable as the material of the diffusion sheet 6. (1) A film or plate coated with a light diffusing substance. (2) A film or plate having a light diffusing property by itself. (3) A milky white resin film or plate. It is to be noted that the diffuser sheet 6 is more closely adhered to the light guide plate 1 than the close contact with the light guide plate 1 when the diffuser sheet 6 is disposed with a space between the light guide plate 1 and the light guide plate 1 so that total reflection is ensured inside the light guide plate 1. There is little loss inside the light plate 1, and light can be reflected sufficiently. Further, the diffusion sheet 6 may be formed in a plurality of layers.

The light source reflection plate 7 reflects light from the surface of the linear light source 2 opposite to the light guide plate 1 to the light guide plate 1 side so that the light can be used efficiently. As the material of the light source reflector 7, it is preferable to use the same material as the back reflector 5. The distance between the linear light source 2 and the light source reflector 7 may be kept uniform by interposing a spacer between them.

The present invention is not limited to the above-mentioned embodiment. For example, in addition to the light guide plate 1 having a uniform thickness as shown in FIG. 1, a light guide plate 1 having an inclined surface portion formed on the back surface side such that the thickness becomes thinner as the distance from the linear light source 2 increases is used. May be used (see Figure 3). By changing the thickness of the light guide plate 1 as described above, the light incident on the light guide plate 1 at an angle of total reflection is gradually changed in its traveling direction each time the total reflection is repeated. Since the light is emitted from the surface side of the light guide plate 1 beyond the critical angle, more light is emitted compared to the light guide plate having a uniform thickness, and the brightness is high enough to be compatible with the color liquid crystal TV. can get.

However, when the light guide plate 1 as shown in FIG. 3 is used, since the thickness of the light guide plate 1 becomes thin on the end face reflection plate 3 side, the light reflection on the side face of the light guide plate 1 perpendicular to the tube axis of the linear light source 2 is reduced. Becomes weak again near the edge reflector 3. As a result, the light directly or totally reflected by the corners 4b of the light guide plate 3 on the side of the end face reflector 3 is smaller than that near the central portion of the end face reflector 3, and the corners 4b of the light guide plate on the side of the end face reflector 3 is smaller. The brightness decreases at. In order to correct this, in addition to the change in the area ratio of the light diffusion / transmission part 4 in the vicinity 4a of the side surface of the light guide plate, the area ratio of the light diffusion / transmission part 4 in the corner part 4b of the light guide plate on the side of the end face reflection plate 3 is changed. (See FIG. 4). In other words, in the direction parallel to the tube axis of the linear light source 2, the rate of change increases as it gets closer to the side surface of the light guide plate 1, and in the direction perpendicular to the tube axis of the linear light source 2, it becomes closer to the end face reflection plate 3. The start point at which the area ratio of the light diffusing and transmitting portion 4 starts to change with increasing ratio draws an arc with the light guide plate corner portion 4b inside.

A lens sheet may be arranged on the surface of the diffusion sheet 6 (not shown). The lens sheet is for raising the angle of light emitted from the surface of the diffusion sheet 6 to increase the front brightness. As the material of this lens sheet, for example, the following materials are preferable. (1) Translucent resin film having one side processed into a shape with many prisms (2) Translucent resin film with a layer having many prisms formed on one side (3) Light exit surface is more than light entrance surface A translucent resin film with a rough surface. Examples of the translucent resin film include a polycarbonate resin film, an acrylic resin film and a polyethylene terephthalate resin film.

Further, a side reflector may be arranged on the side surface of the light guide plate which is perpendicular to the tube axis of the linear light source 2 (not shown). The side reflector reflects the light that is emitted from the side surface of the light guide plate and is not returned to the light guide plate 1 side so that the light can be used efficiently. The material of the side reflector is preferably the same as that of the end reflector 3.

Further, since the brightness of the line light source 2 is dark at both ends, when the line light source 2 having a length equal to or shorter than the end face of the light guide plate 1 on which the line light source 2 is arranged is used, The brightness decreases at the corners of the light guide plate on the light source 2 side. In order to correct this, a change in the area ratio of the light diffusion / transmission part 4 at the corner of the light guide plate on the side of the linear light source 2 may be added.

[0024]

[Effect of device]

 Since the surface emitting device of the present invention is configured as described above, the following effects can be obtained.

That is, the light radiated directly or by total reflection at a position far from the side surface of the light guide plate perpendicular to the tube axis of the linear light source has a constant area ratio in the direction parallel to the tube axis of the linear light source. While being scattered by the light diffusing and transmitting part, it is guided to the surface side of the light guide plate, while the light radiated directly or by total reflection near the side surface of the light guide plate that is perpendicular to the tube axis of the linear light source becomes the tube axis of the linear light source. The light is diffused and guided to the surface side of the light guide plate, where the area ratio increases while the rate of change increases as it approaches the end of the light guide plate in the parallel direction.

Therefore, as compared with the conventional surface light emitting device, the amount of light guided to the surface of the light guide plate near the side surface of the light guide plate is increased to improve the brightness, and thus the surface of the light guide plate can be uniformly surface-emitted.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a surface emitting device.

FIG. 2 is a schematic diagram showing a change in area ratio of a light diffusion / transmission part in an embodiment of the surface emitting device according to the present invention.

FIG. 3 is a sectional view showing another embodiment of the surface emitting device.

FIG. 4 is a schematic diagram showing a change in area ratio of a light diffusion / transmission part in another embodiment of the surface emitting device according to the present invention.

FIG. 5 is a schematic diagram showing a change in area ratio of a light diffusing / transmitting portion in an example of a surface emitting device according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 light guide plate 2 line light source 3 end face reflection plate 4 light diffusion / transmission part 4a light guide plate side surface vicinity 4b light guide plate corner part 5 back reflection plate 6 diffusion sheet 7 light source reflection plate

Claims (2)

[Scope of utility model registration request] 1. A transparent light guide plate is provided with a linear light source on one end face and an end face reflection plate on the other end face opposite to each other, and a light diffusion / transmission part is formed on the back surface of the light guide plate. In the surface emitting device in which the back reflector is arranged, the diffusion sheet is arranged on the surface of the light guide plate, and the light source reflector is arranged so as to cover the surface of the line light source opposite to the light guide plate, The area ratio of the light diffusion / transmission part in the vicinity of the side surface of the light guide plate at a right angle increases while increasing the rate of change as it approaches the side surface of the light guide plate in the direction parallel to the tube axis of the linear light source. A surface emitting device, which has a large change and whose starting point where the area ratio of the light diffusing and transmitting portion starts to change is an arc with the side surface of the light guide plate as the inside. 2. An inclined surface portion is formed on the back surface side of the light guide plate such that the thickness thereof becomes thinner as the distance from the linear light source increases, and a light diffusion / transmission portion is formed on the back surface of the light guide plate including the inclined surface portion, and The area ratio of the light diffusion / transmission part at the corner of the light guide plate is
In the direction parallel to the tube axis of the linear light source, the rate of change increases as it approaches the side surface of the light guide plate, and in the direction perpendicular to the tube axis of the line light source, the rate of change increases as it approaches the end face reflection plate. The surface emitting device according to claim 1, wherein the starting point where the area ratio of the light diffusing and transmitting portion starts to change draws an arc with the corner of the light guide plate inside.