JPS6363083A - Surface light source - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a surface light source, and more specifically, to a surface light source that can be installed as a backlight source on the backside of a variety of display cells, particularly a liquid crystal display cell, and which can significantly improve light output efficiency. Relating to an improved surface light source.

(Prior Art) In recent years, with the rapid development of the information society, terminal devices that transfer various types of information to humans have come into widespread use.

Most of these terminal displays are so-called CRTs, and although these CRTs have many advantages such as excellent color display functions, image adjustment functions, and fewer signal cables, they do not require high-voltage power supplies or thick walls. Because it requires a display tube made of glass, it is large, heavy, and takes up space, so various types of wall-mounted displays have been proposed, mainly for wall-mounted, portable, and portable applications. Of these, the most promising is a liquid crystal display that can be driven by an IC and can be easily colored.

(Problems to be solved by the invention) Conventional liquid crystal displays have a light-reflecting layer on the back and display information using external light from the front, and do not require a special light source. Widely used as displays for desktop calculators, battery-powered calculators, watches, etc. However, when such liquid crystal displays are used in terminals or televisions instead of conventional CRTs, the viewing angle, contrast, and display quality are poor due to insufficient brightness, especially for 10- to 12-inch LCDs. Make the size larger than 8
When used for large-capacity display of about 20 to 25 lines of 0 characters, problems arise in terms of display quality.

Furthermore, since no special light source is attached, the display quality is affected by changes in external light environment conditions, and there is a drawback that the display function is completely lost in the absence of external light.

In order to solve these problems, there has recently been much research into backlight sources installed on the backside of liquid crystal displays. These backlight sources include organic dispersion type EL,
A variety of products have been proposed, including thin-film EL, products using light-emitting diode arrays, combinations of light sources such as fluorescent lamps and lamps with light guide plates, Fournel-type dedicated light panels, and lighting boxes, but none for large displays. However, there is no known material that is satisfactory in terms of uniformity, light efficiency, color rendering properties, etc.

Among these, a promising method is a method in which a light source such as a fluorescent lamp is installed on the side of a translucent panel such as an acrylic board, and light is emitted from one side of the panel. Firstly, if the panel is made thinner than the diameter of the fluorescent lamp, there is a problem that the light guide efficiency will be significantly reduced.Secondly, most of the introduced light is straight light parallel to the light emitting surface, so the light emitted from the light emitting surface is There is a problem of low efficiency, and a third problem is that the larger the panel is made, the more the difference in illuminance occurs between the vicinity of the light source and the center of the panel.

Furthermore, when using a fluorescent lamp as a light source, the amount of light from the fluorescent lamp is always uniform, so it is not possible to arbitrarily control the amount of light on the light emitting surface, and this is subject to individual differences among LCD display users and the usage environment. unable to respond. In addition, considering not only the amount of light, that is, brightness, but also white balance, color rendering, and eyelid fatigue of the user, it is also desirable to adjust the wavelength from the light emitting surface to obtain light of an appropriate hue. In this case, only white light is emitted, which has the disadvantage that electrical regulation is not possible.

Therefore, the main object of the present invention is to provide a surface light source that is large enough to be substituted for a CRT, whose light output panel can be made thin regardless of the size of a light source such as a fluorescent lamp, and which has excellent light output efficiency. .

Another object of the present invention is to provide a surface light source that is large enough to replace a CRT and whose light intensity and/or wavelength can be easily adjusted according to the light environment in which it is used and the individual differences of users. It is to provide.

These objects of the present invention have been achieved by the following invention.

(Means for solving the problems) That is, the present invention consists of a light source and a light emitting panel,
In a surface light source in which the destination panel includes a light source storage section, a light guide surface, a light distribution section, a light guide section, a light reflection layer, and a light output surface,
The light source is enclosed in the light source storage part, and the light reflection layer is made up of a concave curved surface on the bottom of the light distribution part and a convex curved surface of the light guiding part, and most of the light source light is emitted from the concave curved surface and the convex curved surface. This is a surface light source characterized by having a shape that causes reflected light to be oriented at an angle with respect to the surface.

(Preferred Embodiments) Next, the present invention will be described in further detail with reference to the accompanying drawings that schematically show preferred embodiments of the surface light source of the present invention.

FIG. 1 shows a cross-sectional view of one example of the surface light source of the present invention, and FIG.
The figure shows a plan view thereof, and FIG. 3 shows a cross-sectional view of a conventional surface light source.

In a conventional surface light source using an acrylic plate or the like, as shown in FIG. etc., and the diameter of the light output panel B is smaller than the diameter of the fluorescent lamp A.
When the thickness of the light source is made thinner, there is a drawback that the introduction efficiency of the light source light 1 decreases. It is also known that the light source A is provided on a different plane from the light emitting panel B, and the light source light is reflected and introduced parallel to the light emitting panel. If it is thinner than the diameter, the efficiency of introducing light generated from the light source A will be low.

Furthermore, although the light guide efficiency can be improved by increasing the thickness of the light emitting panel B, this does not meet the current trend toward single-layer design and weight reduction. Furthermore, it is reported that the light emitted from the light source A has a low light output efficiency from the light emitting surface 3 because a large proportion of the light is transmitted through the light emitting panel B in a straight line parallel to the light emitting surface. The illuminance of the light emitting surface 3 was high, and the further away from the light source A, the lower the illuminance was, and the illuminance was non-uniform over the entire light emitting surface 3.

In addition, when using a fluorescent lamp as a light source, the amount of light from the fluorescent lamp is always uniform, so it is not possible to arbitrarily control the amount of light on the light emitting surface. Unable to respond to the environment. In addition to the amount of light, i.e., brightness and darkness, we also consider white balance, color rendering,
Considering the user's eye strain, it is desirable to adjust the wavelength from the light emitting surface to obtain light of an appropriate hue, but if the light source is a fluorescent lamp, only white light is emitted, so electricity The problem is that it is impossible to adjust the

The surface light source of the present invention solves the problems of the prior art as described above, and as schematically shown in FIGS. 1 and 2, it consists of a light source A and a light emitting panel B. A light source storage part 2 that stores the light source A1, a light guide surface 6, a light distribution part 10 that distributes the introduced light 1 and guides it to the light guide part 4, a light guide part 4 that guides the introduced light 1 to the light output surface 3, It consists of a light reflection layer 8 and a light emitting surface 3, the light rf, A is enclosed in the light source storage part 2, and the light guide part 4 preferably contains the light source A.
The light reflecting layer 8 becomes thinner as the distance from the light distribution section 1 increases.
The bottom of the light emitting surface 3 has a concave curved surface 12, and the bottom of the light exit surface 3 has a convex curved surface 13. It is characterized by a shape in which the light is reflected by the concave curved surfaces 12 and 13 and reflected at an angle directed to the light exit surface 3, and preferably the concave curved surface 12 and the convex curved surface 13 are continuous curved surfaces. It is something.

With the configuration as shown below, even if the thickness of the light guide section 4 of the light output panel B is made thinner than the diameter of the fluorescent lamp A that is the light source, the introduced light can be distributed by the light distribution section 10. , and is reflected by the reflective surface 8 on the side facing the light emitting surface 3 (-th order reflected light) and reaches the light emitting surface 3 as reflected light, so that the light guiding efficiency of the light source light 1 is not reduced. Also, as in the illustrated example,
By making the bottom surface of the light distribution section 10 a concave curved surface 12, the introduced light is uniformly distributed and guided to the light guide section 4 according to the curvature of the curved surface. In addition, the light uniformly distributed and guided in this way is also reflected by the convex curved surface 13 formed at the bottom of the light emitting surface 3 as light having an angle with respect to the light emitting surface 3 according to its curvature, and the emitted light is Since the light is emitted not only in one direction but in a wide range of directions, the viewing angle of the display 7 is significantly expanded. Preferably, the concave curved surface 12 and the convex curved surface 13 are a continuous curved light reflecting layer 8, so that no streaks of light are observed when viewed from the display 7. On the other hand, concave surface 1
2 and the convex curved surface 13, the concave curved surface 12, and the convex curved surface 13
If the bottom or top of the screen is not a continuous curved surface, the reflection of light at the boundary, bottom or top of the screen will be non-uniform, and when viewed through the display 7, a problem arises in that a striped pattern of brightness will be observed.

Therefore, by adopting the above configuration, the problems of panel thickness, light guide efficiency, light output efficiency, non-uniform illuminance, and viewing angle of the display in the prior art can be solved at the same time.

Furthermore, in another preferred embodiment of the present invention, a light control filter 11 is provided around the light source A. This dimmer filter 1
1 can freely change the intensity and hue of the light from the light source A, and has the function of a light amount filter and/or a wavelength filter.

First of all, when the light control filter 11 is a light amount filter, any structure may be used as such a light amount filter as long as it can adjust the amount of light emitted from the fluorescent lamp A. Some preferred examples are as follows.

(1) A mode in which a layer that can control the light of the fluorescent lamp is formed around the fluorescent lamp A, and the fluorescent lamp can be rotated.

In this embodiment, the above-mentioned layer becomes a light amount filter, and for example, a method of forming a layer capable of blocking or absorbing light such as black or other color, a method of forming a layer capable of reflecting light such as white or metallic color, etc. Either is fine. Such a light amount control layer is made by using a suitable ink or paint, and this is applied to the fluorescent lamp A.
Print around the area, or apply using methods such as rolling, spraying, electrostatic painting, baking, or inkjet methods.
Methods such as evaporation, CVD, sputtering, etc., or methods of forming a dyed layer in advance and dyeing it afterwards, forming it directly on a light source, or forming it on another transparent substrate in advance and bonding it together, etc. It may be formed by any of the following methods. Of course, such a light intensity filter is not formed uniformly on the tube wall of fluorescent lamp A, but is formed in a line, stripe, or dot shape with an appropriate density difference or density difference, or Light shielding material layers with different concentrations are formed stepwise or continuously. By forming the light amount filter 11 having such a configuration and rotating the fluorescent lamp A by appropriate means (not shown), the amount of light reaching the light output surface can be easily controlled.

(2) A mode in which the fluorescent lamp A is fixed and a rotatable light amount filter 11 is provided around it.

The principle of this example is exactly the same as the case (1) above, and for example, a tubular filter 11 made of transparent glass or plastic is formed, and the surface thereof has a density difference or concentration difference as in (1) above. A method of forming a light absorption layer or a light reflection layer may be used. Furthermore, after the tubular body is provided, a film or the like having a light amount adjustment function as described above may be wrapped around the surface of the tubular body. It is also possible to make a flexible cylindrical sheet and feed it by rotating it on two axes. By providing the light amount filter 11 having such a configuration and rotating this filter 11 with appropriate means (not shown) such as a gear or a belt, the amount of light reaching the light output surface can be arbitrarily controlled. Although the above description has been made using a tubular filter as an example for ease of explanation, the filter is not limited to these examples, and may have any shape and movable mechanism.

Further, when the light control filter 11 is a wavelength filter, the object of the present invention can be achieved by coloring the light absorption layer in the above embodiments (1) and (2) in a color that absorbs light of a specific wavelength. can. That is, the light control filter 11 is yellow, orange, red 1. The light control filter 1 with such a configuration can be colored in any order with blue, green, violet, or any intermediate color thereof.
By rotating or sliding 1 according to the user's preference, the wavelength of light from the light source to the light output surface can be arbitrarily controlled. In addition, for television applications,
Essential hue: A adjustment is the easiest! ■This is an effective method for achieving.

Furthermore, the light control filter 11 used in the present invention can serve as the above-mentioned light amount filter and wavelength filter at the same time. For example, there are two methods: one is to provide both the light amount adjustment and color tone adjustment functions on the same filter, and the other is to separate the filters into multiple filters, overlap them, and control them independently. It is possible to make more adjustments to the amount of light, color tone, shade of color, etc., and allows for more precise adjustments.

The light output panel B that realizes the effects of the present invention as described above is
It can be formed from any material with excellent translucency, such as glass material, but from the viewpoint of ease of molding and translucency, acrylic resin, acrylonitrile-styrene copolymer resin,
It is preferably formed from a translucent plastic material such as cellulose acetobutyrate resin, cellulose propionate resin, polymethylpentene resin, polycarbonate resin, polystyrene resin, polyester resin, or a composite material or copolymer material thereof.

In addition, reaction-curing epoxy resins, acrylic resins,
Methacrylic resin, urethane resin, etc. can also be used. As the molding method, any known method such as injection molding, compression molding, cast molding, cutting, polishing, etc. can be applied.

The light reflecting layer 8 of the light emitting panel B obtained in this way is
As shown in FIG. 1, a light-reflecting metal such as nickel, aluminum, silver, or gold is vapor-deposited on the light-emitting surface 3 and other parts of the light source housing 2 except for the light-guiding surface 6.

It is formed by sputtering, plating, silver mirror reaction, etc., or by applying a reflective metal-containing paint, or by bonding a light-reflecting material such as an aluminum sheet, so that the light source light l leaks outside of panel B. It is effective to prevent this, including the effect of reflecting some of the leaked light back into the interior. Furthermore, it is also effective to form a layer with a light shielding agent or a light absorbing agent in unnecessary portions to prevent undesigned external light from entering. These reflective surfaces can be treated with scattering properties or use retroreflective materials such as glass beads, as long as they do not disturb the optical design, or they can also be diffusely reflected using uneven surfaces. It is possible.

Further, it is preferable to form a light diffusion layer 9 on the light emitting surface 3. For example, the light emitting surface may be sandpaper polished, sandblasted, honed, puffed, hairline processed, embossed, etc. during or after molding of the light emitting panel. A transparent resin layer that has been roughened by processing, press processing, etc., or contains a pre-diffusible material such as white pigments such as silica, alumina, titanium oxide, zinc oxide, barium sulfate, and magnesium oxide, or glass beads with a specific diameter, By forming by coating methods such as dipping, roll coating, blade coating, and spray coating, or by adhering these layers, the light reaching the light emitting surface 3 is diffusely reflected or diffused, and the illuminance from the light emitting surface 3 is made uniform. The viewing angle can be expanded as well. In addition, such a light diffusion layer can be prepared by separately preparing a ground glass plate, a pre-diffusing glass plate, a pre-diffusing plastic sheet, etc., and integrating it at the same time during molding, or by placing it between the liquid crystal self and the light emitting surface 3 during use. They may be placed or pasted together. Further, it is also advantageous in terms of efficiency improvement and thermal design to arrange a light-reflecting condensing mirror or a heat sink on the side of the light source opposite to the light source accommodating portion.

The light emitting panel B as described above has a light emitting surface 3,
The light source storage section 2 and the light distribution section 10 form a recess, and by placing the liquid crystal display 7 in this recess, the back side of the liquid crystal display 7 is illuminated, and the liquid crystal display 7 can be clearly seen regardless of the environment. You can do it like this. Further, by forming the light emitting panel of the present invention into such a shape, the thickness of the entire display including the back light source can be reduced, and the overall weight can be reduced.

The present invention has been described above by exemplifying the preferred embodiments of the present invention, but most of the light from the light source A is reflected by the concave curved surfaces 12 and 13, and the reflected light has an angle with respect to the light output surface 3. The surface light source of the present invention is not limited to the shape shown in the drawings, and may have any shape as long as it can emit light as light. For example, light source storage section 2 (light source A) of light output panel B
is not limited to the two locations shown in the figure, but may be one, three, or four locations, and the shape of the light emitting panel B is not limited to a rectangle, but may be disc-shaped, elliptical plate-shaped, polygonal, or with rounded corners. Therefore, the shape of the light source is not limited to the rod-shaped fluorescent lamp A, and may be any shape such as an annular shape depending on the shape of the light emitting panel B.

(Function/Effect) In the surface light source of the present invention as described above, the light from the light source is not incident on the light guide part in parallel due to the above configuration,
Since it is incident as reflected light with directionality, most of the incident light can be oriented at an angle with respect to the light output surface, and the light from the light source can be efficiently guided to the light output surface. Can be done.

Further, in a preferred embodiment of the present invention, the light guide portion can be made thin regardless of the thickness of the fluorescent lamp used as the light source, so that the demand for thinner and lighter displays can be satisfied.

Also, for the same reason, by making the light source storage part thicker than the diameter of the fluorescent lamp, fitting more than half of the fluorescent lamp into it, and connecting this light source storage part to the light guide part by the light distribution part, Since the light guide can be made thinner than the diameter of the fluorescent lamp, most of the light emitted from the fluorescent lamp can be collected and introduced into the light guide. Therefore, even if the light guide section is thinner than the diameter of the fluorescent lamp, the efficiency of using the light from the light source can be significantly increased.

Further, a light reflecting layer consisting of a concave curved surface 12 and a convex curved surface 13, which are preferably continuous curved surfaces, is formed on the outer surface of the light output panel except for a part of the light output surface, especially at the bottom of the light distribution section 10 and the bottom of the light output surface. By appropriately controlling the angle and shape of these light sources, it is possible to evenly distribute the light from the light source over the entire light emitting surface, making the illumination of the light emitting surface more uniform and expanding the viewing angle of the display. be able to.

Furthermore, in a preferred embodiment of the present invention, by attaching a dimmer filter around the light source, the amount and/or wavelength of the light reaching the light emitting surface can be easily and arbitrarily controlled by the user. It is possible to use a display such as a liquid crystal display with the optimum amount of light (brightness/darkness) and/or optimum wavelength light (hue) for each user.

(Example) Example 1 Using polymethyl methacrylate resin (Barabet HR1 manufactured by Kyowa Gas Chemical Co., Ltd.), the shape was as shown in Figs. 1 and 2, and the size was 200 ma + X 120 mm, the center thickness of the light guide part was 4 mm, and the peripheral thickness was A light output panel with a size of 10a+m and a thickness of 25mm in the light source housing part was molded using an injection molding method,
Aluminum was vacuum-deposited on the outer surface except for the light-emitting surface and the light-guiding surface to form a light-reflecting layer. Further, glass beads (manufactured by Toshiba Ballotini) were kneaded in the above acrylic resin at a ratio of 10% by weight to prepare a 2 ml 11 thick sheet, which was bonded to the light emitting surface. Two 15W fluorescent lamps were used as light sources, and they were fitted into the recesses formed in the light source housing, and the top surface was sealed with an aluminum sheet to provide a surface light source of the present invention.

When a liquid crystal display was placed on the light emitting surface of this surface light source and the surface light source was turned on, the liquid crystal display showed excellent viewing angles and contrast, and exhibited a high display function that was uniform throughout.

Example 2 A tubular body with a rotating handle provided at one end was formed from the acrylic resin of Example 1, and black dots were printed on the surface of the polychloride resin, the number of dots changing continuously. Vinyl sheets were pasted together, two dimmer filters were used, and α was applied. A 15W fluorescent lamp is attached to each of these, fitted into the recess of the light source storage part of the light output panel of Example 1, and the upper surface is sealed with an aluminum sheet, so that the above-mentioned dimmer filter can be freely rotated from the outside. In this way, a surface light source of the present invention was obtained.

When a liquid crystal display was placed on the light emitting surface of this surface light source and the surface light source was turned on, the liquid crystal display became a light-emitting type, with excellent viewing angles and contrast, and exhibited a high display function that was uniform throughout. In addition, by gradually rotating the light control filter, the brightness and darkness of the liquid crystal display changed, making it possible to adjust the brightness of the display surface in response to individual differences and external light.

Example 3 Instead of the dot-printed sheet in Example 2, a sheet with a width equal to the circumferential length of the fluorescent lamp and having seven highly transparent rainbow colors arranged vertically and continuously was used, and the other parts were the same as in Example 2. A surface light source of the present invention was obtained in the same manner as in Example 2. When this surface light source was used in the same manner as in Example 1, it was possible to change the hue of light on the display surface to various hues.

As described above, the surface light source of the present invention is very useful as a back light source for various displays such as liquid crystal displays.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing a cross section of an example of a surface light source of the present invention, FIG. 2 corresponds to the plan view of FIG. 1, and FIG. 3 shows a cross section of a conventional surface light source. It is a figure shown diagrammatically. A: Light source B: Light output panel 1: Light source light 2: Light source storage section 3: Light output surface 4: Light guide section 5: Reflected light 6: Light guide surface 7: Liquid crystal display 8: Light reflection layer 9: Light diffusion layer 10: Light distribution section 11;:l! ] Optical filter 12: concave curved surface 13; convex curved surface Fig. 7 Fig. 2 Fig. 3

Claims (8)

[Claims] (1) In a surface light source consisting of a light source and a light output panel, where the light output panel consists of a light source storage section, a light guide surface, a light distribution section, a light guide section, a light reflection layer, and a light output surface, the light source is located in the light source storage section. The light reflecting layer is comprised of a concave curved surface on the bottom surface of the light distribution section and a convex curved surface on the light guide section, and most of the light source light is oriented at an angle with respect to the light output surface between the concave curved surface and the convex curved surface. A surface light source characterized by having a shape that provides reflected light having the following characteristics. (2) The surface light source according to claim (1), wherein the concave curved surface and the convex curved surface are continuous curved surfaces. (3) The light output panel consists of a single translucent plate, and the center of the light source housing provided at at least one end of the translucent plate is
The surface light source according to claim 1, wherein the surface light source is formed above the center of the light guide section. (4) The surface light source according to claim (1), wherein the surface of the light emitting panel excluding the light emitting surface and the light guiding surface is light reflective. (5) A surface light source according to claim (1), wherein the light emitting surface is pre-diffusive. (6) The surface light source according to claim (1), wherein the light emitting panel is rectangular and a light source is provided at at least one end thereof. (7) The surface light source according to claim (1), wherein the light emitting panel is integrally molded from a translucent resin. (8) The surface light source according to claim (1), wherein a dimmer filter is attached to the periphery or a part of the light source.