JPH05341132A - Surface light source unit - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a surface light source unit used for a backlight of a display device, wherein the surface light source unit is made thin by integrating a light refraction portion and a light diffusion portion of the surface light source unit, and The purpose is to improve productivity. [Configuration] One light control plate 21 is provided on the surface 11c of the light guide plate 11. The light control plate 21 has a large number of prism units 23 whose lower surface directs light from the cold cathode tubes 12a and 12b in a direction perpendicular to the front surface of the surface light source unit.
It has a prism unit group 23 composed of a and 23b, and has a rough surface 22 on the upper surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface light source unit,
In particular, it relates to a surface light source unit used as a backlight of a liquid crystal display device.

In order to improve the visibility of the display device, a structure in which a light source (backlight) is provided on the back side of the display surface of the display device is generally used, and requires planar illumination over the entire surface of the liquid crystal display device or the like. A surface light source unit is required for a backlight light source of a display device.

FIG. 8 shows an example of application of the surface light source unit. In the figure, reference numeral 1 denotes a liquid crystal panel, which forms a display pattern by orienting the liquid crystal on the display surface 2 in a predetermined pattern. In the figure, reference numeral 3 denotes a surface light source unit, which is arranged at a portion on the rear surface side of the liquid crystal panel 1 with a surface facing the liquid crystal panel 1 as a light source surface 4 and illuminates the entire surface of the liquid crystal panel 1 from the rear surface side.

Such a surface light source unit has high brightness,
In addition, it is required that the entire surface of the light source has uniform brightness.

[0005]

2. Description of the Related Art FIG. 9 shows a conventional surface light source unit. In the figure, reference numeral 11 denotes a light guide plate of the surface light source unit 10, which is made of a light transmissive resin such as acrylic resin, and has a side surface 11 thereof.
Lights emitted from the cold cathode tubes 12a and 12b and the cold cathode tubes 12a and 12b respectively face the side surfaces 11a and 11a.
Holders 13a and 13b for collecting light toward 11b are provided.

A reflection plate 14 having a high light reflectance is provided on the back surface 11d of the light guide plate 11, and a large number of prism units 15a, 15b are provided on the front surface 11c of the light guide plate 11 so as to cover the entire surface 11c. .. is provided with the lenticular plates 15 in series. On the surface of the lenticular plate 15 opposite to the surface having a large number of prism units 15a, 15b, ..., A milky white light diffusing plate 16 serving as a light source surface of the surface light source unit is provided.

The operation of the surface light source unit will be described below. When the cold cathode tubes 12a and 12b emit light, the light is collected by the holders 13a and 13b toward the side surfaces 11a and 11b, and the light guide plate 1 is emitted from the side surfaces 11a and 11b.
It is made to enter into 1. The light incident on the inside of the light guide plate 11 has the reflecting plate 14 disposed on the back surface 11d, and therefore the front surface 11c.
The light is emitted from the light guide plate 11.

A lenticular plate 15 is disposed on the surface 11c of the light guide plate 11, and a large number of prism units 15a, 15b, ... In order to face the front surface of the light source unit 10 in a direction substantially vertical, the surface 11
The light emitted from c is divided into a large number of prism units 15a, 1
After entering 5b ..., It is vertically incident on the light diffusion plate 16.

The light diffusing plate 16 is milky white and diffuses the incident light. Therefore, the light incident from the lenticular plate 15 is diffused, and the unevenness of the incident light is blurred and emitted. Therefore, the light emitted from the light diffusion plate 16 is
6 The brightness is uniform over the entire surface.

[0010]

However, in the above-mentioned conventional surface light source unit, a large number of prism units 15a, 15b, ... Of the lenticular plate 15 are arranged to direct light in a direction perpendicular to the front surface of the surface light source unit. The light diffusing plate 16 serves as a refraction portion, and the light diffusing plate 16 functions as a light diffusing portion for uniforming the brightness of the backlight.

Therefore, there are problems that the number of parts is large, the surface light source unit is thick, and the productivity is inefficient.

The present invention has been made in view of the above points, and by integrating a light refracting portion and a light diffusing portion,
It is an object of the present invention to provide a surface light source unit that solves the above problems.

[0013]

In order to solve the above-mentioned problems, the invention according to claim 1 is directed to a light guide plate for guiding the light incident inside from the side surface to be emitted from the surface, and the light guide plate of the light guide plate. A light source that is disposed so as to face the side surface and that allows light to enter the inside of the light guide plate from the side surface of the light guide plate, and one light-transmissive light control plate that is disposed on the surface of the light guide plate. And a light control plate for directing light passing through the inside of the light guide plate and emitted from the surface in a direction substantially perpendicular to a front surface of the surface light source unit. The light refraction portion for refracting the light and the light diffusion portion for diffusing the light transmitted through the light control plate body are integrally formed.

According to a second aspect of the present invention, the light diffusing section according to the first aspect is a rough surface on the side opposite to the surface of the light control plate on which the light refracting section is arranged.

According to a third aspect of the present invention, in the light diffusing section according to the first aspect, the light control plate main body contains diffusing particles made of an inorganic or organic compound having a refractive index different from that of the light control plate main body. It is a configuration.

[0016]

In the structure having the light refracting portion and the light diffusing portion, which are integrated with each other, the light diffusing plate is unnecessary.

According to the above configuration, the light emitted from the surface light source unit is complicatedly refracted and diffused when passing through the rough surface. In this way, the rough surface constitutes the light diffusing section, and the surface of the conventional lenticular plate opposite to the light refracting section is simply roughened to form the light refracting section and the rough surface. The light diffusing portion is integrally formed.

According to the above-mentioned structure of claim 3, the light emitted from the surface light source unit is repeatedly generated by the diffusing particles scattered in the light control plate body when passing through the light control plate body. Refracted and diffused. In this way, the light control plate body containing the light diffusing particles constitutes the light diffusing portion, and only by forming the light refracting portion in the sheet material containing the light diffusing particles, the light refracting portion and the The light control part main body containing the diffusing particles and the light diffusing portion are integrally formed.

[0019]

1 is a sectional view of a first embodiment of a surface light source unit according to the present invention. In the figure, the same parts as those in FIG. 9 are designated by the same reference numerals, and the description thereof will be omitted.

The surface light source unit 20 holds the light emitted from the cold cathode tubes 12a and 12b corresponding to the light source in the holder 13
The light is condensed by a and 13b, and the side surfaces 11a and 1 of the light guide plate 11 are collected.
The light is taken in from 1 b, efficiently emitted from the surface 11 c of the light guide plate 11 by the action of the reflection plate 14, and provides high-intensity, uniform-brightness illumination through the light control plate 21.

The light control plate 21 has a prism unit group 23 in which a plurality of prism units 23a, 23b, ... The surface (upper surface) opposite to 23 has a rough surface 22 corresponding to a light diffusing portion, and the prism unit group 23 is disposed so as to face the surface 11c of the light guide plate 11.

Therefore, the light emitted from the surface 11c of the light guide plate 11 enters the prism unit group 23, is refracted in the direction perpendicular to the front surface of the surface light source unit 20, and the main body of the light control plate 21 is guided. It propagates and goes to the rough surface 22. Rough surface 22
Causes the light passing therethrough to be complexly refracted and diffused.
As a result, the light emitted from the rough surface 22 becomes illumination with uniform brightness over the entire rough surface 22.

The light control plate 21 is made of a light-transmitting resin such as polycarbonate, and the prism unit group 23 has a large number of rings corresponding to the cross-sectional shape of the desired prism unit group on the side surface, like the conventional lenticular plate. It is formed by rolling with a roller provided with continuous protrusions.

Therefore, the light control plate 21 of the present embodiment has the prism unit group 2 after the conventional lenticular plate is manufactured.
It can be manufactured only by roughening the surface opposite to the surface No. 3, and the equipment required for the conventional process can be used as it is.

Thus, the prism unit group 23 and the rough surface 2
2 can be easily integrally molded, and the light diffusing plate which is conventionally required is not required. Therefore, the surface light source unit 20 of the present embodiment can be thinned and the number of parts can be reduced. The property is also improved.

FIG. 2 shows a second surface light source unit according to the present invention.
The sectional view of an example is shown. In the figure, the same parts as those in FIGS. 1 and 8 are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, reference numeral 31 denotes a light control plate of the surface light source unit of this embodiment, in which the prism unit group 23 is arranged in contact with the surface 11c of the light guide plate 11. The main body of the light control plate 31 contains diffusing particles 33 having a diffusing effect such as silica, barium sulfate, and titanium oxide to form a light diffusing section.

Therefore, the light emitted from the surface 11c of the light guide plate 11 is refracted by the prism unit group 23 of the light control plate 31 and is directed substantially vertically to the front surface of the surface light source unit 30. In the process of passing through the main body of the light control plate, it is repeatedly diffused by the diffusing particles 33 contained therein, and when the light is emitted from the light control plate 31, the entire light source surface 32 has a uniform brightness. As a result, the surface light source unit 30 becomes a backlight with high brightness and uniform brightness over the entire surface.

The light control plate 31 is made of a light-transmissive resin sheet material such as polycarbonate containing diffusing particles 33.
It can be easily molded by rolling it with a roller for molding the prism unit group 23 or the like, and by including the diffusing particles 33 in the resin material before molding, only the same process as the conventional process is performed. It can be manufactured.

As described above, the surface light source unit of this embodiment can be manufactured by the same manufacturing process as the conventional one, only by changing the material of the light control plate. Further, like the surface light source unit of the first embodiment, it is possible to reduce the thickness,
And productivity is improved.

FIG. 3 shows a third surface light source unit according to the present invention.
The sectional view of the important section of an example is shown. In the figure, the same parts as those in FIGS. 1, 2 and 8 are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, reference numeral 41 denotes a light control plate of the surface light source unit of this embodiment, and a Fresnel lens 43 having a large number of lens units 43a, 43b, ... Having the Fresnel lens 4 of the light control plate 41
The light control plate 2 of the first embodiment is provided on the surface (upper surface) opposite to 3
As in the case of No. 1, it has a rough surface 22, and the lens unit group 43 is arranged so as to face the surface 11c of the light guide plate 11.

Light guide plate 11 having opposite side surfaces as light incident surfaces
Then, the emission angle of the light emitted from the surface 11c of the light guide plate 11 is roughly determined by the reflection angle of the reflection plate 14,
When the light is emitted in the vicinity of the side surface 11a of the light guide plate 11, the emission angle is smaller than that in the case where the light is emitted from the vicinity of the central portion of the light guide plate 11.

On the other hand, a large number of lens units 43a, 43b.
The curvature of each is determined such that the light incident from the surface 11c of the light guide plate 11 is refracted in the predetermined direction most efficiently with respect to the incident angle.

Therefore, the light emitted from the surface 11c of the light guide plate 11 enters the Fresnel lens 43, and the respective lens units 43a, 43b ... Refracts in the direction. After that, as in the case of the above-described first embodiment, the light propagates through the main body of the light control plate 41 and enters the rough surface 22, is diffused on the rough surface 22, and has high brightness and uniform brightness over the entire rough surface 22. Lighting

The light control plate 41 of the surface light source unit 40 of this embodiment can also be manufactured by rolling with the above roller, and the Fresnel lens 43 and the rough surface 22 can be easily integrally molded.

FIG. 4 shows a fourth surface light source unit according to the present invention.
The sectional view of the important section of an example is shown. 1 to 3,
The same parts as those in FIG. 8 are designated by the same reference numerals and the description thereof will be omitted.

In the figure, reference numeral 51 denotes a light control plate of the surface light source unit of this embodiment. As shown in the figure, a plurality of lens units 43a, 43b, ... Are connected in the same manner as in the third embodiment. The Fresnel lens 43 formed and provided is disposed so as to face the light emitting surface 11c of the light guide plate 11. Also, the light control plate 3
The main body of No. 1 contains diffusing particles 33 as in the case of the second embodiment.

For the above reason, the light emitted from the light emitting surface 11c of the light guide plate 11 is refracted by the Fresnel lens 43 of the light control plate 51 and directed in the direction perpendicular to the front surface of the surface light source unit 50. After that, when passing through the main body of the light control plate 51, it is repeatedly diffused by the diffusion particles 33 contained therein, and when it is emitted from the light control plate 51, the light source surface 5
2. The backlight has a uniform brightness over the entire surface.

The light control plate 51 can also be easily formed by rolling a light-transmissive resin sheet material such as polycarbonate containing the diffusion particles 33 with the above-mentioned roller or the like, and the surface light source unit can be made thinner. And productivity can be improved.

As described above, the light control plates 21, 31, 41 and 51 of the surface light source unit of this embodiment are the prism unit group 2.
3 or the Fresnel lens 43, and the light diffusing portion having the rough surface 22 or the diffusing particles 33 contained in the light control plate body are integrally provided, so that the number of parts can be reduced and the surface light source The unit can be made thinner and the productivity can be improved.

Next, another embodiment using the light control plate 21 of the first embodiment of the present invention shown in FIG. 1 will be described with reference to FIGS.
It will be explained based on. In the figure, the same parts as those in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

FIG. 5 shows a fifth surface light source unit according to the present invention.
The sectional view of an example is shown.

In the figure, the light control plate 21 is arranged such that the surface 11c of the light guide plate 11 and the rough surface 22 face each other. Therefore, the light emitted from the surface 11 c of the light guide plate 11 is first diffused by the rough surface 22 and then refracted by the prism unit group 23 to travel in a direction perpendicular to the front surface of the surface light source unit 60. Thus, even if the light control plate 21 is arranged with the rough surface 22 facing the surface 11c of the light guide plate 11, the same effect as in the case of the first embodiment can be obtained.

Further, on the back surface 11d of the light guide plate 11 of this embodiment, the reflection material 61 formed by applying white paint or the like has a ratio of the reflection material 61 occupying per unit area toward the center from the side surfaces 11a and 11c. It is arranged to increase. Therefore, the reflectance per unit area of the back surface 11d of the light guide plate 11 is minimum near the side surfaces 11a and 11c and maximum near the central portion.

Generally, in a light guide plate having opposite side surfaces as a light incident surface, the light density in the vicinity of the side surface close to the light source such as a cold cathode tube is the highest, and in the vicinity of the central portion far from the light source is the lowest. The light emitted from is dark in the central part.

In the surface light source unit 60 of this embodiment, the reflection material 61 maximizes the reflectance in the vicinity of the central portion, so that the light emitted from the surface 11c of the light guide plate 11 has a uniform brightness regardless of the region. Therefore, by combining with the light control plate 21, more uniform illumination can be performed. Further, in the present embodiment, the reflectance is changed by the reflecting material 61, but the present invention is not limited to this, and the reflectance may be changed by changing the surface roughness.

FIG. 6 shows a sixth surface light source unit according to the present invention.
The sectional view of an example is shown.

In the figure, reference numeral 71 denotes a light guide plate of the present embodiment, and the surface 11c is concave so that the side surfaces 11a and 11b of the light guide plate 71 have the largest plate thickness and the central part has the smallest thickness.

As described above, in the light guide plate having the opposite side surfaces as the light incident surface, the incident angle of the light incident from the inside of the light guide plate to the surface of the light guide plate is at the center compared to the case where the light is incident near the side surface. When the light is incident on the light guide plate, the light becomes larger, and total reflection of light is likely to occur at the central part of the light guide plate, so that the light guide plate cannot be thinned.

In the light guide plate 71 of the present embodiment, the surface 11c is made concave so that the center part becomes the thinnest, and the incident angle of light at the center part of the light guide plate 71 can be made small to prevent total reflection. it can. Therefore, the light guide plate 71 can be made thinner, the surface light source unit 70 can be made lighter, and by combining it with the light control plate 21, the surface light source unit can be made even thinner.

FIG. 7 shows a seventh embodiment of the surface light source unit according to the present invention.
The front sectional drawing of an Example is shown.

In the figure, reference numeral 80 denotes a surface light source unit, which is a cold cathode fluorescent lamp 1.
2b shows the case of a single-sided light source. In the figure, reference numeral 82 denotes a light source reflector, which reflects light incident from the facing side surfaces 11b of the light guide plate 81.

The light guide plate 81 is a light guide plate for one side light source and prevents total reflection of light at a portion away from the cold cathode fluorescent lamp 12b, and allows light entering from the light source arranged on one side to be guided by the light guide plate 8.
The surface 11c is concave so that the portion closer to the light source reflection plate 82 than the central portion becomes the thinnest because it propagates to the entire surface.

Therefore, in the light guide plate 81 of this embodiment, the light incident from the cold cathode fluorescent lamp 12b arranged on one side is guided by the light guide plate 8.
It is possible to efficiently and uniformly emit light from the surface 11c of No. 1 and by combining with the light control plate 21, a surface light source unit having high brightness and uniform brightness can be constructed at low cost.

Although the reflector 61 is used only in the light guide plate 11 in the above embodiment, the present invention is not limited to this, and may be used in combination with the light guide plates 71 and 81. In the light guide plates 71 and 81, the cross-sectional shape is V
Although it is a concave surface of the mold, it is not limited to this and may have a U-shaped cross-sectional shape, for example.

Further, in the above embodiment, the prism units 23a, 23b, ... Are arranged with the same shape and at a uniform pitch, but the present invention is not limited to this, and the incident angle of the light incident on the light control plate is not limited to this. According to the above, different shapes and non-uniform pitches may be arranged.

[0058]

As described above, according to the first aspect of the invention, since the light refracting portion and the light diffusing portion are integrally formed,
The number of parts can be reduced, the surface light source unit can be made thinner, and the productivity can be improved.

According to the second aspect of the present invention, the light refracting portion and the light diffusing portion can be integrally formed only by subjecting the conventional lenticular plate to the roughening treatment, so that the conventional manufacturing process is not required to include the roughening treatment. It suffices to add it, and the light control plate integrally including the light refraction portion and the light diffusion portion can be easily manufactured.

According to the third aspect of the present invention, the material of the conventional lenticular plate only needs to be changed to a material containing diffusing particles, and the light control plate is the same process as the process of manufacturing the conventional lenticular plate. Can be manufactured in.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment of a surface light source unit according to the present invention.

FIG. 2 is a sectional view of a second embodiment of the surface light source unit according to the present invention.

FIG. 3 is a sectional view of an essential part of a third embodiment of the surface light source unit according to the present invention.

FIG. 4 is a sectional view of an essential part of a fourth embodiment of the surface light source unit according to the present invention.

FIG. 5 is a sectional view of a surface light source unit according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view of a surface light source unit according to a sixth embodiment of the present invention.

FIG. 7 is a sectional view of a surface light source unit according to a seventh embodiment of the present invention.

FIG. 8 is a diagram illustrating an example of uses of a surface light source unit.

FIG. 9 is a cross-sectional view of a conventional surface light source unit.

[Explanation of symbols]

 11 Light guide plate 11a, 11b Side surface 11c Surface 21, 31, 41, 51 Light control plate 22 Rough surface 23 Prism unit group 23a, 23b Prism unit 33 Diffusing particle 43 Fresnel lens 43a, 43b Lens unit

Claims (3)

[Claims] 1. A light guide plate (11) that guides light incident inside from side surfaces (11a, 11b) so as to be emitted from the surface (11c), and is disposed so as to face the side surfaces (11a, 11b). Light sources (12a, 12b) that allow light to enter the inside of the light guide plate (11) from the side surfaces (11a, 11b).
And a light-transmitting light control plate (21, 31, 41, 51) disposed on the surface (11c) of the light guide plate (11), the light control plate comprising: (21, 31, 41, 51) directs the light passing through the inside of the light guide plate (11) and emitted from the surface (11c) in a direction substantially perpendicular to the front surface of the surface light source unit. The light refraction part (23, 43) and the light diffusion part (22, 3) for diffusing light transmitted through the light control plate body.
3) A surface light source unit characterized in that it is integrally configured with (3). 2. A surface, characterized in that the light diffusing portion according to claim 1 is constituted by a rough surface (22) on a side opposite to a surface of the light control plate on which the light refracting portion is arranged. Light source unit. 3. The diffusion part according to claim 1, wherein the light control plate body contains diffusing particles (33) made of an inorganic or organic compound having a refractive index different from that of the light control plate body. A surface light source unit characterized by the above.