JPS6332584A - Flatting 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 [Industrial Field of Application] The present invention relates to a flattened light source with a uniform luminance distribution that can be obtained with a general light source and is particularly suitable for a backlight source of a liquid crystal.

[Conventional technology]

The brightness of liquid crystal varies depending on the viewing angle, and has a so-called viewing angle. Therefore, a backlight source for a liquid crystal device is required to be sufficiently bright and have a uniform brightness distribution in the direction of the viewing angle. Conventionally, a method for removing light unevenness using a flat light source is disclosed in Japanese Patent Application Laid-open No. 1512-1983.
There is a method described in No. 6, which is characterized by providing a reflective layer on the planar member so as to have a substantially reciprocal relationship with the luminous flux emitted from the surface of the planar member, and Light unevenness is removed by transmitting through the planar member, but the light emitted from the light source, especially the light emitted from the fluorescent lamp, is diffused light, and even when a transparent material is used for the above-mentioned planar member. , the light that passes through the planar member must be a diffused beam. Therefore, the light beam emitted from the surface of the planar member in the prior art is a diffused beam of light, and It is difficult to make measurements that take into account all of the light that is diffused and radiated into the surface space, and it is difficult to obtain a reflective layer that has a reciprocal relationship.

Further, although the setting position of the reflective layer is not considered, in reality, the size and position of the reflective layer are limited, and it can be said that it is very difficult to handle.

[Problem that the invention seeks to solve]

In order to obtain a planar light source with no uneven light using the planar member provided with the reflective layer in the prior art described above, the film of the reflective layer must be It is necessary to install the reflective layer, and if the installation position of the reflective layer deviates from the above-mentioned relative position, a great effect will not be obtained. Therefore, the size and position of the reflective layer are limited, and it has the disadvantage that it is very difficult to handle. Further, when the above-mentioned flat light source is used as a backlight source for a liquid crystal, the conventional method in which the brightness in a specific direction is not determined due to the relationship with the viewing angle often causes problems.

The object of the present invention is to take the above-mentioned drawbacks into account and to transmit light through a brightness unevenness removing member having a film made of a light reflecting material or a light absorbing material in which the brightness distribution on the surface of a one-sided member is almost inverted. ``The purpose is to obtain a planarized light source with uniform brightness in a direction almost directly above a planar member.

[Means for solving problems]

The above objective is achieved by applying photographic technology. That is, a photograph is taken of the inverted state of the almost vertical luminance distribution of the flat light source, printed on photographic paper with the same dimensions as the light emitting surface of the flat light source, and the printed photograph is printed in full size on a transparent or translucent film. The uneven brightness removing member is installed between the light source and the diffusing member or on the diffusing member, or it is directly printed or transferred onto the diffusing member to remove the uneven brightness from the light source. If transmitted light is obtained, a flat light source with uniform brightness and no unevenness can be obtained.

[Effect]

The light emitted from the light source passes through the brightness unevenness removing member before and after the diffusion member, and the brightness unevenness removing member is photographed with the almost vertical brightness distribution of the flattened light source reversed. Therefore, on the photographic paper photographed and printed, the brightest part is the darkest, the darkest part is the brightest, and the intermediate brightness parts are respectively on the diffusion member in the absence of the brightness unevenness removing member. Since it has reversed brightness and darkness, the light source light that passes through the brightness unevenness removing member printed or transferred with the pattern of the photographic paper is reflected or absorbed depending on the brightness in the bright areas, and then passes through the flat surface. As a light source, it is possible to obtain uniform brightness without uneven brightness. In addition, when transmitting through the diffusion member after passing through the brightness unevenness removing member, the brightness unevenness is averaged and further diffused as described above, so the brightness unevenness can be reduced by one cycle and made uniform. , a planar light source suitable for a back light source of a liquid crystal can be obtained.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an exploded perspective view showing an embodiment of a flattened light source according to the present invention, and FIG. 2 is a diagram showing the difference in luminance distribution depending on the presence or absence of a luminance unevenness removing member in the above embodiment. In FIG. 1, a U-shaped fluorescent lamp 1 is used as a light source, and the U-shaped fluorescent lamp 1 is installed inside a shallow box-shaped reflective member 2 made of an aluminum plate, and the inner surface of the reflective member 2 is coated with white lacquer. Coated. With the U-shaped fluorescent lamp 1 turned on, take a photo using a versatile film above the fluorescent lamp 1, print the developed negative onto photographic paper with the same dimensions as the light emitting area of the flat light source, and print this on the base paper. For example, a brightness unevenness removing member 4 is manufactured by printing to the original size on a transparent film such as polyester with silver ink, and the brightness unevenness removing member 4 is placed on the reflective member 2, and then a diffusion member made of a milky white acrylic plate is manufactured. 3 is installed to constitute a flat light source.

Curve 5 in FIG. 2 shows the luminance distribution in the vertical direction on the diffusing member 3 along the arrow in FIG. 1 when the flattened light source is turned on, and the luminance unevenness removing member 4 is removed. The above luminance distribution in this case is shown by curve 6. That is, from the song IIA6 in FIG. 2, it can be seen that the brightness is highest right above the arc tube of the U-shaped fluorescent lamp 1 in the flat light source, but the inserted brightness unevenness removing member 4 does not change the brightness distribution as described above. The state where the magnitude of the brightness at each position is inverted,
Since printing is carried out using shading of silver ink, areas with high brightness are printed darkly, more light is reflected, and the amount of light transmitted through the uneven brightness removing member 4 is reduced.

In this way, since the amount of transmitted light decreases depending on the magnitude of the brightness, the brightness on the diffusion member 3 is smoothed as shown by the curve 6.

The above printing is available in black, silver, and white colors.

Black ink absorbs light, white ink transmits some light depending on the thickness of the ink film, but silver ink reflects light and has the best light utilization. Furthermore, although the transparent film was printed in the above embodiment, it is also possible to print directly on the diffusion member 3 for use.

The difference in shading formed on the uneven brightness removing member can of course be adjusted by the printing method, but the printing onto photographic paper, which is a step before printing, can also be adjusted by the method, so it is possible to It is easy to select the conditions.

In addition, by applying the photographic technology that is a feature of the present invention, it is possible to easily form a brightness unevenness removing member, without being affected by the type or shape of the light source, in the same way as in the above embodiments, and to A flat light source with uniform brightness can be obtained.

〔Effect of the invention〕

As described above, the planar light source according to the present invention includes a light source, a reflecting member, and a diffusing member, and in a planar light source that supplies light only in one direction, the luminance distribution in the vertical direction of the planar light source is inverted. A film made of a light-absorbing material or a light-reflecting material is formed on a transparent or semi-transparent material using a photographic film, and a brightness unevenness removing member on which the film is formed is formed.
Regardless of the type and shape of the light source, by applying photographic technology, it is possible to easily create a flat light source with uniform surface brightness by providing it between the light source and the diffusion member, on the diffusion member, or directly on the diffusion member. A brightness unevenness removing member for uniformizing the surface brightness of the flattened light source that can be obtained is:
The shading of the formed pattern can be easily adjusted depending on the printing conditions on the photographic paper and the printing conditions on the film, so it is possible to freely select the optimum condition.

Further, according to the present invention, it is possible to configure the planar light source to be thin, and in the minimum state, it is formed by only the sum of the thickness of the material of one reflecting member, the diameter of the light source lamp, and the thickness of the diffusing member. It has the characteristic of being able to

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a flattened light source according to the present invention, and FIG. 2 is a diagram showing the difference in luminance distribution depending on the presence or absence of a luminance unevenness removing member in the above embodiment. 1...Light source 2...Reflecting member 3...Diffusion member 4...Patent attorney representing brightness unevenness removing member
Junnosuke Nakamura Book 1 Figure'! j'2 figure 18□, t1 no, +, no\2-1

Claims (1)

[Claims] 1. In a flat light source that includes a light source, a reflecting member, and a diffusing member and supplies light in only one direction, a photographic film photographing the vertical luminance distribution of the flat light source in an inverted state is used to detect light absorbing material or A film made of a light reflecting material is formed on a transparent or semi-transparent material, and a brightness unevenness removing member on which the film is formed is provided between a light source and a diffusing member, or on the diffusing member, or directly on the diffusing member. Features a flat light source.