JP2006269210A - Surface light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dual-side light emitting surface light source device capable of reducing power consumption and ensuring uniform and high luminance even if the quantity of light from the light source is changed. <P>SOLUTION: The surface light source device provides dual-side emission of light incident from a light source 3. The light source 3 has a plurality of luminous elements 4. The device comprises adjusting means 31, 32 for adjusting the quantity of light from the light source 3 by controlling the lighting of the luminous elements 4. The adjusting means 31, 32 make the quantity of light from the light source smaller when second light-emitting surfaces 2B, 22, 23 are allowed to emit light, compared with the case where first light-emitting surfaces 2A, 12, 13 are allowed to emit light. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a double-sided light-emitting surface light source device mounted as a backlight on a transmissive or transflective liquid crystal display panel, for example.

In recent years, cell phones that can be folded and rotated with respect to the main unit have a small screen size LCD panel (sub-panel) behind the large screen size LCD panel (main panel). The main panel and the sub-panel are both illuminated using a single backlight device that emits light on both sides using a plurality of light emitting elements as light sources (see, for example, Patent Document 1).
JP 2002-287144 A

  In the double-sided light emitting backlight device as described above, as shown in FIG. 5, even when only the sub-panel 102 having a small screen size is illuminated, all the light-emitting elements 103 are illuminated in the same manner as when the main panel 101 is illuminated. Since it is necessary to turn on the power, there is a problem that power consumption increases.

  The present invention has been made in view of the above problems, and its object is to reduce the power consumption by reducing the light amount of the light source when illuminating the sub-panel as compared with the light amount of the light source when illuminating the main panel. It is to provide a surface light source device that can ensure uniform and high luminance even if the amount of light is changed.

  In order to solve the above-described problems and achieve the object, a surface light source device according to the present invention is a surface light source device that emits light incident from a light source 3 on both sides, and the light source 3 includes a plurality of light emitters. 4 and adjusting means 31 and 32 for adjusting the light quantity of the light source 3 by controlling the lighting of the light emitter 4, and the adjusting means 31 and 32 emit light from the first light emitting surface 2A. The light amount of the light source when the second light emitting surface 2B emits light is made smaller than the light amount of the light source.

  Further, in the above configuration, the display device 21 having a display area smaller than the first light emitting surface is disposed on the second light emitting surface side, and the adjustment unit controls lighting for each light emitter, The light source for causing the second light emitting surface to emit light by making the number of light emitting members for emitting light from the second light emitting surface smaller than the number of light emitting members for emitting light from the first light emitting surface. Reduce the amount of light.

  Moreover, the said structure WHEREIN: The said adjustment means light-emits the said 2nd light emission surface by lighting the mutually adjacent light-emitting body arrange | positioned among the several light-emitting bodies.

  Moreover, the said structure WHEREIN: The said adjustment means makes the said 2nd light emission surface light-emit by lighting the light-emitting body mutually spaced apart arrange | positioned among the several light-emitting bodies.

  In addition, the surface light source device according to the present invention includes the light guide member 2 that emits light incident from the light source on both the first light emitting surface 2A and the second light emitting surface 2B on the back surface, and the first light emission. First optical members 12 and 13 for diffusing and condensing light emitted from the surface, and a second optical member for diffusing and polarizing light emitted from the second light emitting surface and reflecting unpolarized light 22 and 23.

  As described above, according to the present invention, the power consumption can be reduced by reducing the light amount of the light source when illuminating the sub-panel as compared with the light amount of the light source when illuminating the main panel. Uniform and high brightness can be ensured even if the angle is changed.

  Further, since the light quantity of the light source can be controlled only by switching instead of current control, the circuit configuration can be simplified.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS The best mode for carrying out the present invention (referred to as an embodiment, hereinafter the same) will be described below with reference to the accompanying drawings.

  The embodiment described below is an example as means for realizing the present invention, and the present invention can be applied to a modified or modified embodiment described below without departing from the spirit of the present invention.

  FIG. 1 is an exploded perspective view showing a surface light emitting device according to an embodiment of the present invention.

  As shown in FIG. 1, the double-sided light-emitting backlight device exemplified as the surface light source device according to the present invention has a light-emitting surface on opposite surfaces, and the first light-emitting surface on one side (surface) has a first light-emitting surface. The display panel (main panel) 11 is illuminated, and the second display panel (sub-panel) 21 is illuminated with the other (back) second light emitting surface. Each of the main panel 11 and the sub-panel 21 is, for example, a transmissive or transflective electro-optical (liquid crystal) color panel in which a plurality of pixels are formed in a matrix, and the display area of the second display panel 21 ( (Screen size) is about 1/3 smaller than the display area (screen size) of the first display panel 11.

  The backlight device includes a light guide member 2 made of a flat transparent resin, sheet-like first optical members 12 and 13 and a light shielding member 14 disposed on the surface of the light guide member 2, and The sheet-like second optical members 22 and 23 and the light-shielding member 24 disposed in a stacked manner on the back surface of the light guide member 2 and the light source unit 3 having the light emitting elements 4 such as a plurality of LEDs are made of white resin. It is accommodated in a rectangular reflection frame 5 having both ends opened.

  The first light emitting surface includes the surface 2A of the light guide member and the first optical members 12 and 13 (and the opening 14a of the light shielding member 14), and the second light emitting surface is formed of the light guide member. It has a back surface 2B and second optical members 22 and 23 (and an opening 24a of the light shielding member 24). The light source unit 3 and the reflection frame 5 are components common to the first and second light emitting surfaces.

  In the light source unit 3, light emitting elements 4 such as a plurality of (for example, four) LEDs are arranged in a line on a substrate 3a on which a predetermined wiring pattern is printed, and a connector 3b for connection is provided at an end of the substrate 3a. Have

  The light guide member 2 is composed of a rectangular plate material having a substantially uniform thickness, and the light source unit 3 is disposed close to one of the four side end surfaces in the thickness direction as the incident surface 2a. The light incident from the surface 2a is emitted from both the output surfaces 2A and 2B on the front and back surfaces while being diffused and scattered.

  Linear prism grooves or hemispherical dot patterns are formed on the front surface 2A and the back surface 2B of the light guide member 2 by grinding.

  The first optical members 12 and 13 include a sheet-shaped diffusion member 12 disposed on the surface of the light guide member 2 and a sheet-shaped light collecting member 13 disposed on the surface of the diffusion member 12. The diffusion member 12 diffuses light emitted from the surface of the light guide member 2. The condensing member 13 has a function of a condensing lens that condenses and emits the light diffused by the diffusing member 12. Further, the first light shielding member 14 has an opening 14 a corresponding to the display area of the main panel 11, and a peripheral portion other than the opening 14 a is located in the opening 14 a in the light emitting area of the light collecting member 13. Light emitted from other than the corresponding area is blocked. The main panel 11 is fixed to the peripheral portion of the opening 14a of the light shielding member 14 with a double-sided tape or the like.

  The second optical members 22 and 23 include a sheet-like diffusion member 22 disposed on the back surface of the light guide member 2 and a sheet-shaped light collecting member 23 disposed on the surface of the diffusion member 22. The diffusion member 22 diffuses light emitted from the back surface of the light guide member 2. The condensing member 23 functions as a condensing lens that condenses and emits the light diffused by the diffusing member 22, and only the P wave of the light diffused by the diffusing member 22 (about 50% light). It has the function of a polarizing lens that transmits and emits light and reflects N waves. Further, the second light shielding member 24 has an opening 24 a corresponding to the display area of the sub-panel 21, and the peripheral portion other than the opening 24 a corresponds to the opening 24 a in the light emitting area of the light collecting member 23. Shields light emitted from other areas. The sub panel 21 is fixed to the peripheral portion of the opening 24a of the light shielding member 24 with a double-sided tape or the like.

  The light condensing member 23, which is the second optical member, has the function of a polarizing lens. Light emitted to the second light emitting surface when the main panel is illuminated is condensed by the second optical member. This is to prevent a shadow corresponding to the display area of the sub-panel from being reflected by the member 23.

  Further, by roughly processing the dot pattern on the back surface 2B of the light guide member 2, the amount of light emitted from the back surface 2B can be increased, and the above-mentioned shadow can be eliminated.

  Next, light emission control of the light source unit in the backlight device of this embodiment will be described.

  FIG. 2 is a block diagram for controlling the lighting of the light emitting elements of the backlight device of this embodiment. FIG. 3A is a view of the backlight device of the present embodiment as viewed from the first light emitting surface (front surface), and FIG. 3B is a view of the backlight device as viewed from the second light emitting surface (back surface).

  As shown in FIG. 2, the light source unit 3 of the present embodiment has a mode in which the CPU 31 mounted inside a mobile phone or the like illuminates only the main panel, a mode in which the main panel and the sub panel are illuminated simultaneously, or only the sub panel. The switching circuit 32 determines whether the illumination mode is selected. The switching circuit 32 receives a control signal corresponding to the determined mode from the CPU 32 and switches between lighting / non-lighting for each light emitting element 4.

  Specifically, the CPU 31 and the switching circuit 32 as the adjusting means control lighting / non-lighting for each light emitting element 4 to adjust the light amount of the light source unit 3 and emit light from the first light emitting surface. As compared with the above, the light amount of the light source when the second light emitting surface emits light is reduced.

  That is, the CPU 31 and the switching circuit 32 indicate the number of light emitting elements when the second light emitting surface is caused to emit light (mode in which only the sub panel is illuminated), and when the first light emitting surface is caused to emit light (illuminate only the main panel). By controlling lighting for each light emitting element so that the number of light emitting elements is smaller than the number of light emitting elements in the mode and the mode in which the sub-panel is illuminated simultaneously, the light amount of the light source when the second light emitting surface emits light is reduced.

  In the example shown in FIG. 3, all the light emitting elements are turned on when the main panel is illuminated (FIG. 3A), and only some of the light emitting elements are turned on when the sub panel is illuminated. Control is performed as shown in FIG.

  In the case where there are an even number (four) of the light emitting elements 4 shown in FIG. 4, at the time of sub-panel lighting, two central light emitting elements arranged adjacent to each other among all the light emitting elements are lit or arranged apart from each other. A form in which the outer two are turned on is preferable.

  In addition, when there are an odd number (5) of light emitting elements, at the time of sub-panel illumination, the central three arranged adjacent to each other among all the light emitting elements are turned on, or the outer two arranged apart from each other. The form which lights an individual is preferable.

  When only the two light emitting elements in the center are turned on as shown in FIG. 4A, the light emitting region R1 of the light guide member 2 is long and long in the direction from the incident surface of the light guide member 2 to the opposite end surface. When only the two outer light-emitting elements are turned on as shown in FIG. 4B, the light-emitting region R2 is long and long in the direction of the opposing end surface on the side of the incident surface 2a.

  According to the embodiment, the power consumption can be reduced by reducing the light amount of the light source when illuminating the sub-panel as compared with the light amount of the light source when illuminating the main panel, and even if the light amount of the light source is changed. Uniform and high brightness can be secured.

  Further, since the light quantity of the light source can be controlled only by switching instead of current control, the circuit configuration can be simplified.

It is a perspective view which decomposes | disassembles and shows the surface emitting device of embodiment which concerns on this invention. It is a block diagram which carries out lighting control of the light emitting element of the backlight apparatus of this embodiment. It is the figure (a) which looked at the backlight apparatus of this embodiment from the 1st light emission surface (front surface), and the figure (b) which looked from the 2nd light emission surface (back surface). It is a schematic diagram explaining lighting control of a light emitting element. It is a schematic diagram which shows the conventional surface light-emitting device.

Explanation of symbols

2 Light guide member 2a Incident surface 2A Surface of light guide member (first light emitting surface)
2B Rear surface of light guide member (second light emitting surface)
3 Light source unit (light source)
3a Substrate 3b Connector 4 Light emitting element (light emitter)
5 Reflection frame 11 Main panel (display device)
12 Diffusion member (first optical member)
13 Condensing member (first optical member)
14 1st shielding member 21 Subpanel (display device)
22 Diffusing member (second optical member)
23 Condensing member (second optical member)
24 2nd shielding member 31 CPU (adjustment means)
32 Switching circuit (adjustment means)

Claims (5)

A surface light source device that emits light from a light source on both sides,
The light source has a plurality of light emitters,
An adjusting means for adjusting lighting of the light source by controlling lighting of the light emitter;
The surface light source device characterized in that the adjustment means reduces the light amount of the light source when the second light emitting surface emits light compared to the light amount of the light source when the first light emitting surface emits light. A display device having a display area smaller than the first light emitting surface is disposed on the second light emitting surface side,
The adjusting means controls lighting for each of the light emitters so that the number of light emitters when the second light emitting surface emits light is smaller than the number of light emitters when the first light emitting surface emits light. The surface light source device according to claim 1, wherein the light amount of the light source when the second light emitting surface emits light is reduced.   3. The surface light source according to claim 2, wherein the adjustment unit causes the second light emitting surface to emit light by lighting a light emitter adjacent to each other disposed in the center among the plurality of light emitters. apparatus.   3. The surface light source according to claim 2, wherein the adjusting unit causes the second light emitting surface to emit light by lighting a light emitting body that is disposed outside and is spaced apart from the plurality of light emitting bodies. apparatus. A light guide member that emits light incident from a light source on both the first light emitting surface and the second light emitting surface on the back surface;
A first optical member for diffusing and collecting light emitted from the first light emitting surface;
A second optical member that diffuses and polarizes light emitted from the second light emitting surface and reflects light that is not polarized;
A surface light source device comprising:

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