JP2010103013A - Planar light emitting illumination device and display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a planar light source element array in which a luminance distribution in a plane does not become un-uniform by canceling a phenomenon of becoming dark or light suddenly in an interface line between planar light source elements as compared with other parts, in case a plurality of small planar light source elements are arrayed closely to make a large-sized planar light source element. <P>SOLUTION: In the planar light emitting illumination device, a plurality of linear or planar illumination units (1) are arranged in an array shape and a light diffusing member (2) is arranged parting with each of the illumination units with a constant distance, and when a shortest distance in a non-light-emitting region between neighboring illumination units (1) is A, and diffusion angle characteristics of the light diffusing member (2) in a part right above the non-light-emitting region is defined by an angle θ in which luminance decreases by 10% from the maximum luminance, a distance D from the illumination unit (1) to the diffusion member (2) satisfies D x tanθ>3A. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a surface-emitting illumination device using an array-shaped light source, and more particularly to a thin and uniform surface-emitting illumination device using light from an LED light source. Furthermore, the present invention relates to a display device such as a liquid crystal television using the lighting device.

In recent years, liquid crystal televisions have become widespread as flat-screen televisions. Since a liquid crystal television is not a self-luminous type, it is necessary to irradiate light from the back surface, and a backlight (requires a surface emitting illumination device). A backlight of a liquid crystal television is required to have a light emitting surface with a large area and to have uniform luminance over the front surface.
The backlight for the image display device guides the light of the light source arranged on the side surface of the light guide plate in the front direction with the light guide plate, and makes the light source uniform on the diffusion sheet and the light source on the back side of the illumination surface, There is a direct method in which light is made uniform with a diffusion sheet. The direct method tends to be thicker because the light source is provided on the back of the device. For this reason, in fields where thinness is required, such as mobile phones, mobile PCs, and car navigation systems, the light source is provided on the side to reduce the thickness. The possible edge light method was the mainstream.

  On the other hand, in recent years, there has been an increasing demand for larger displays and higher brightness mainly in televisions and personal computer monitors. In particular, with the increase in the size of the display, in the edge light system, the ratio of the length of the peripheral portion where the light source can be arranged to the display area decreases, and the amount of light is insufficient, so that sufficient luminance cannot be obtained. Further, the edge light system has a problem that the weight of the light guide plate increases as the display becomes larger. As described above, in the edge light system, it has become difficult to meet market demands such as an increase in display size and brightness in recent years.

  Therefore, in large display applications, a direct system using a plurality of light sources is adopted. In this method, the ratio of the luminous flux emitted from the light source is high, and the number of light sources can be increased freely. That is, since the amount of light can be increased freely, the required high brightness can be easily obtained.

  However, the direct method needs to solve unique problems such as elimination of lamp image, thinning, and energy saving. In particular, the lamp image appears as brightness unevenness much more remarkable than the edge light system. For this reason, it is difficult to eliminate the lamp image by means conventionally used in the edge light system, that is, means such as a diffusion film in which a diffusion material is applied to the film surface.

  Therefore, a diffusion sheet containing a diffusion material is widely used. In this method, in order to obtain good diffusibility and light utilization efficiency, inorganic particles and cross-linked organic fine particles are added to the base resin such as methacrylic resin, polycarbonate resin, styrene resin, vinyl chloride resin. And a method of preparing a light diffusion sheet.

  Until now, backlights using cold cathode tubes, which have high light utilization efficiency as a light source and are low cost, have been the mainstream. The lamp image of the cold cathode tube can be diffused by a diffusion sheet to form a uniform surface light source. In order to make a conventional illuminating device a uniform surface light source, it has been possible to realize a surface light source by providing an interval of about 30 mm between the light source and the diffusion sheet.

  In recent years, however, further reduction in power consumption and improvement in color reproducibility of the display are necessary. Therefore, the backlight light source is not a cold cathode tube but uses red, green and blue three-color LEDs or white light. The use of LEDs as light sources is increasing.

  In such a liquid crystal display, the light intensity and mixed color of the light of each color emitted from each LED is made uniform in the space between the surface on which the LED is arranged and the prism sheet and the light diffusion sheet. .

  However, in order to reduce the thickness of the display, it is necessary to increase the number of LEDs and increase the arrangement density in order to make the intensity of the emitted light uniform in a situation where the LED light source and various optical sheets are close to each other to some extent. There is. Therefore, in this case, there are problems that a large number of LEDs are required, resulting in an increase in cost and an increase in power consumption. Further, a method of making the intensity of emitted light uniform by increasing the distance between the light emitting light source and the diffusion sheet is taken, but there is a problem that the thickness of the backlight becomes very large.

  Therefore, as described in Patent Documents 1, 2, and 3, as a method for reducing the thickness and reducing the number of LEDs, a light guide plate is used to multiply reflect light from a light source arranged in a part of the light guide plate. A structure as a surface light source has been proposed. When the light guide plate is used, there is an advantage that the thickness can be reduced and the uniformity of luminance can be improved. However, it is difficult for these lighting devices to change the brightness according to the image for each place, and it is not possible to use such that the dark image portion is darkened and only the bright portion is lit back. Moreover, in patent document 4, in the illuminating device comprised in the array form which arranged the some light emission light source, each said light emission light source is combined with the corresponding light guide, and has comprised each illumination unit. The light guide is configured to receive a light beam emitted from the light emitting light source, reflect and scatter the light, and emit a light velocity developed in a linear or planar shape. Although the device is described, there is a problem that the boundary line of the tiled surface light source can be seen and the luminance at the boundary line changes although it is possible to light partially.

JP 2006-236770 A JP 2006-233671 A JP 2006-251075 A JP-A-9-186825

  When a plurality of small surface light source elements are arranged close to each other to make a large surface light source element, the boundary line between the surface light source elements becomes darker or brighter than other portions. When used as a surface emitting illumination device, there are problems that the boundary line between the arrays can be seen and the brightness becomes non-uniform. The problem of the present invention is that the boundary line between arrays cannot be seen. An object of the present invention is to provide a surface emitting illumination device in which the in-plane luminance distribution does not become uneven. It is another object of the present invention to provide a display device using the surface-emitting illumination device.

  The present inventors used the following means in order to solve the above problems.

First, the present invention
In a lighting device configured in an array by arranging a plurality of linear or planar illumination units, a light diffusing member is arranged at a certain distance from each illumination unit, and between two adjacent illumination units If the shortest distance of the non-light-emitting region is defined as A, and the diffusion angle characteristic of the light diffusing member in the portion directly above the non-light-emitting region is defined by the angle θ until the luminance decreases by 10% from the maximum luminance, the diffusibility from the illumination unit The distance D to the member is D × tan θ> 3A
It is the surface emitting illumination device characterized by satisfy | filling.

Further, in the surface emitting illumination device according to the present invention, when the diffusion angle characteristic of the light diffusing member in the portion immediately above the light emitting region of the illumination unit is defined by an angle θ _c until the luminance decreases by 10% from the maximum luminance, The angle θ indicating the diffusion angle characteristic of the light diffusing member in the portion immediately above the non-light emitting region is larger than the angle θ _c indicating the diffusion angle property of the light diffusing member in the portion immediately above the central portion of the light emitting region. It is said surface emitting illumination device characterized by the above.

  In another aspect of the present invention, the illumination unit is composed of a linear or planar light source, or is composed of a light source and a light guide. It is a lighting device. Further, the light emitting source is preferably an LED light source.

  Furthermore, the present invention is a display device characterized in that a transmissive display element is provided on the surface emitting illumination lighting device.

  The present invention makes it possible to make the boundary line of each illumination unit inconspicuous and make the in-plane luminance distribution uniform. When the region that does not emit light is wide, it is necessary to increase the diffusion performance of the member having the light diffusion performance, and to make a certain distance from each illumination unit to the member having the light diffusion performance. When the area not emitting light is narrow, the diffusion performance of the light diffusing member can be lowered, and the distance between each illumination unit and the light diffusing member can be shortened. The thickness can be reduced.

  Moreover, it becomes possible to make a boundary line inconspicuous by improving the diffusion capability of the light diffusing member on the boundary line of each illumination unit as compared with the diffusion capability immediately above the center of each illumination unit. In particular, it is possible to achieve even more uniform brightness by suppressing the phenomenon that the light emitted from each illumination unit overlaps to suppress the phenomenon of being brighter than other parts on the boundary line.

  By providing a transmissive display element on the above lighting device, when all the lighting devices are turned on, the lighting device has a large luminance and a uniform luminance distribution, and each lighting device is turned on independently. It is also possible. By providing a transmissive display element on such a lighting device, it can be used as a backlight that partially emits light, and low power consumption and high contrast can be realized.

Hereinafter, embodiments of the present invention will be described in detail. As shown in FIG. 1, a plurality of illumination units 1 are arranged side by side, and when the illumination units 1 are arranged side by side, the light diffusing member 2 is not arranged in the vicinity of the boundary line where the illumination units 1 overlap. In the state, when the luminance is measured from the front side of the surface emitting illumination, the non-luminous area A is set to 50% or less of the maximum luminance, and the distance from each illumination unit 1 to the light diffusion performance member 2 is D. As shown in FIG. 2, when the diffusion angle characteristic of the light diffusing member is defined as an angle θ until the luminance is reduced by 10% from the maximum luminance, the relationship between A, D, and θ is D × tan θ> 3A.
Install to meet the requirements. If the distance D increases, the boundary line becomes difficult to see, but the entire lighting device becomes thick. Further, even if θ becomes large, the boundary line becomes difficult to see, but there is a problem that the light utilization efficiency is lowered. By reducing the distance A of the non-light-emitting portion as much as possible, the distance D and the diffusion half-value width can be reduced, and a thin and highly efficient lighting device can be realized.

In the illuminating device of the present invention, the high diffusion region 3 in which the angle θ indicating the diffusion performance of the light diffusing member 2 is greater than the angle θ _c indicating the diffusion performance of the central portion in the portion immediately above the non-light emitting region shown in FIGS. By providing the light, it is possible to achieve uniform brightness without overlapping the light from each illumination unit and increasing the light intensity. In order to enhance the diffusion performance, a method of printing white ink in the form of dots, a method of applying a polymer solution containing fine particles, and drying are included.

Each illumination unit is composed of a linear or planar light source. In this case, a cold cathode tube, LED, organic EL element, inorganic EL element, or the like is used as the linear or planar light source. In particular, the light emitting light source is preferably an LED light source.
Moreover, each illumination unit may be comprised with the light emission light source and the light guide. In this case, it is preferable to use a light emitting light source in the form of a dot or a line. Specific examples include a cold cathode tube, an LED, an organic EL element, and an inorganic EL element. In particular, the light emitting light source is preferably an LED light source.

  In particular, when the illumination unit 1 is composed of the point LED light source 4 and the light guide 5, the point LED light source 4 as shown in FIG. 5 is a side emission type and is embedded in the light guide 5. It is preferable that the distance A of the non-light emitting portion can be reduced, and that the uniformity of luminance and the thickness of the light source can be compatible.

<Example 1>
The present invention will be described more specifically with reference to the following examples. However, the present invention is not limited to these examples.

  3 × 3 illumination units that emit light in a 40 mm square positive shape were arranged and arranged. The non-light emitting area A is 2 mm. A diffusion plate having a diffusion angle characteristic of θ = 45 ° was disposed at a position 10 mm away from the illumination device. When all nine lighting devices were turned on, the boundary line was not recognized and was confirmed to be a uniform surface light source.

<Example 2>
9 × 3 lighting devices that emit light in a 40 mm square shape in the positive direction are arranged and arranged in total. The non-light emitting area A is 0.1 mm, and the diffusion angle characteristic is θ at a position 10 mm away from the lighting device. A diffusion plate of _c = 45 ° was arranged. Diffuser was granted dot printing of the white ink theta> theta _c directly on the non-emission regions between the illumination device. When the lighting device was turned on, it was confirmed that the lighting device did not become bright in the boundary region of the lighting device, and the surface light source was uniform.

It is a conceptual diagram which shows the cross-sectional structure of the surface emitting illumination apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the relationship between the diffusion angle and intensity | strength of the member which has the light-diffusion performance which concerns on the 1st Embodiment of this invention. It is a conceptual diagram which shows the cross-sectional structure of the surface emitting illumination apparatus which concerns on the 2nd Embodiment of this invention. It is a conceptual diagram which shows the structure when it sees from the upper surface of the surface emitting illumination device which concerns on the 2nd Embodiment of this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram which shows the one aspect | mode of embodiment which concerns on this invention, (a) is a top view, (b) is sectional drawing cut | disconnected by II.

Explanation of symbols

1. Lighting unit; 3. A member having a light diffusing property, 3. A portion where the diffusing performance is stronger than other portions. LED light source, 5. Light guide

Claims (7)

In a lighting device configured in an array by arranging a plurality of linear or planar illumination units, a light diffusing member is arranged at a certain distance from each illumination unit, and between two adjacent illumination units If the shortest distance of the non-light-emitting region is defined as A, and the diffusion angle characteristic of the light diffusing member in the portion directly above the non-light-emitting region is defined by the angle θ until the luminance decreases by 10% from the maximum luminance, the diffusibility from the illumination unit The distance D to the member is D × tan θ> 3A
The surface emitting illumination device characterized by satisfying the above. In the surface emitting lighting system, the diffusion angle characteristics of the light-diffusing member in the portion directly above the light emitting region of the lighting unit, the brightness is defined by an angle theta _c until drops 10% from the maximum brightness, right above the non-light-emitting region The surface emission characterized in that the angle θ indicating the diffusion angle characteristic of the light diffusing member in the portion is larger than the angle θ _c indicating the diffusion angle characteristic of the light diffusing member in the portion immediately above the center of the light emitting region. Lighting device.   The surface-emitting illumination device according to claim 1, wherein the illumination unit includes a linear or planar light-emitting light source.   The surface-emitting illumination device according to claim 3, wherein the light-emitting light source is an LED light source.   The surface-emitting illumination device according to claim 1, wherein the illumination unit includes a light-emitting light source and a light guide.   The surface-emitting illumination device according to claim 5, wherein the light-emitting light source is an LED light source.   A transmissive display element is provided on the surface-emitting illumination / illumination device according to claim 1.

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