JP2010027367A - Backlight unit, and light guide plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a backlight unit which can not only irradiate brightly a display panel from the rear side but also can attain improvement in added value, and to provide a light guide plate. <P>SOLUTION: The backlight unit 1 is provided with a light guide plate 4 which irradiates a display panel from the rear side by emitting illumination light from a main emission face and a linear light source device 6 which can emit simultaneously two colors by a light-emitting element group being six point light sources arranged along the side face of the light guide plate 4. The light guide plate 4 includes a first light guide plate 41 and a second light guide plate 42 divided into two by corresponding to the group of the light-emitting element group emitting in different colors, and the opposed side faces of the first light guide plate 41 and the second light guide plate 42 have a shading part 43 on which a coating material having light-shielding performance is printed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a backlight unit and a light guide plate that illuminate from the back of a display panel.

  The backlight unit functions as a surface light emitting device that brightly illuminates a display panel such as an LCD by causing the irradiation light to enter from one side surface of the light guide plate and to be emitted from the main irradiation surface of the light guide plate.

  Such a backlight unit is described in Patent Document 1. Patent Document 1 discloses a white light emitting unit that is a light emitting device, a reflector, a light guide plate, an optical sheet, a frame-shaped mold frame that is a case frame, a white light generating unit, a light guide plate, and three optical plates. A backlight assembly is described that includes a storage container for storing a sheet and a mold frame.

The backlight assembly of Patent Document 1 uses a white light emitting unit in which light emitting diodes emitting blue light are arranged along the side surface of a single plate-shaped light guide plate as a light source, and is generated from the light emitting diodes. A lens having a fluorescent member that emits white light upon receiving blue light is provided between the light guide plate and the white light emitting unit.
JP 2006-108606 A

  However, the backlight assembly of Patent Document 1 has only a function of brightly illuminating a display panel that does not emit light by illuminating the display panel with white light from the back side.

  For example, if the content displayed on the display panel can be noticed or the aesthetics can be improved, a backlight unit with high added value can be obtained.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a backlight unit and a light guide plate that can not only illuminate the display panel brightly from the back but also improve the added value.

  The present invention is characterized in that light of a light emitting device that emits light of two or more colors is incident from one side surface of the light guide plate and is emitted from the main light emitting surface as illumination light.

  Since the present invention can emit light of two or more colors from the main light emitting surface of the light guide plate, the appearance can be improved more than the light guide plate that emits only white, and the display panel is partially emphasized. , And can be focused on the observer. Therefore, according to the present invention, it is possible not only to brightly illuminate the display panel from the back side but also to improve the added value.

  In the first invention of the present application, n colors (simultaneously by a light guide plate that illuminates the display panel from the back side by emitting illumination light from the main light emitting surface and two or more point light sources arranged along the side surface of the light guide plate. However, n is provided with the light-emitting device which can light-emit 2 or more and below the number of point light sources).

  Since the light emitting device is provided with two or more point light sources capable of emitting different colors, two or more colors of light can be incident on the light guide plate. Therefore, since two or more colors of light can be emitted from the main light emitting surface of the light guide plate, the aesthetic appearance can be improved as compared with the light guide plate that emits only white light. Further, since the main light emitting surface emits light in multiple colors, the display panel can be partially emphasized or the viewer can be focused.

  The second invention of the present application is characterized in that, in the first invention, the light guide plate is divided corresponding to point light sources emitting light of different colors.

  Since the light guide plate is divided corresponding to the point light sources that emit light in different colors, the color boundary can be visually recognized by the observer.

  A third invention of the present application is characterized in that, in the second invention, a light-shielding portion is provided on the opposing side surfaces of the divided light guide plates.

  Since the light-shielding portions provided on the opposite side surfaces of the divided light guide plates can prevent light leakage from the adjacent light guide plates, the color boundary can be made visible to the observer firmly.

  The fourth invention of the present application is characterized in that, in the third invention, the light shielding portion is obtained by printing a coating material having a light shielding property.

  Since the light-shielding part is formed by printing a light-shielding coating material, the light-shielding part can be thinly formed, so that the divided light guide plates can be arranged without a gap. Therefore, the observer does not mind even if the light guide plate is divided.

  According to a fifth aspect of the present invention, light from a light emitting device capable of simultaneously emitting n colors (where n is 2 or more and the number of point light sources or less) by two or more point light sources is incident from one side. The light guide plate emits from the main light emitting surface as illumination light and irradiates the display panel from the back surface, and is divided according to point light sources emitting light in different colors.

  Since the light emitting device is provided with two or more point light sources capable of emitting different colors, two or more colors of light can be incident on the light guide plate. Therefore, since two or more colors of light can be emitted from the main light emitting surface of the light guide plate, the aesthetic appearance can be improved as compared with the light guide plate that emits only white light. Further, since the main light emitting surface emits light in multiple colors, the display panel can be partially emphasized or the viewer can be focused. Since the light guide plate is divided corresponding to the point light sources that emit light in different colors, it is possible for the observer to visually recognize the color boundary.

  The sixth invention of the present application is characterized in that, in the fifth invention, a light-shielding portion is provided on a side surface opposed to each other by being divided.

  Since the light-shielding portions provided on the opposite side surfaces of the divided light guide plates can prevent light leakage from the adjacent light guide plates, the color boundary can be made visible to the observer firmly.

  The seventh invention of the present application is characterized in that, in the sixth invention, the light shielding portion is obtained by printing a coating material having a light shielding property.

  Since the light-shielding part is formed by printing a coating material having a light-shielding property, the light-shielding part can be thinly formed, so that the divided light guide plates can be arranged without a gap. Therefore, the observer does not mind even if the light guide plate is divided.

(Embodiment)
A backlight unit according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of a backlight unit according to an embodiment of the present invention. FIG. 2 is a perspective view of a light guide plate used in the backlight unit shown in FIG. FIG. 3 is a perspective view of a linear light source device used in the backlight unit shown in FIG. FIG. 4 is a circuit diagram of the linear light source device shown in FIG. In the present specification, the side on which the liquid crystal panel, which is a display panel, is disposed is described as the upper side, and the opposite side is described as the lower side.

  As shown in FIG. 1, the backlight unit 1 is disposed on the back surface of a display panel such as a liquid crystal panel (not shown) used as a sub-display of the mobile phone device. The backlight unit 1 includes a reflective film 2, a case frame 3, a light guide plate 4, a fixed sheet 5, a linear light source device 6, a reflective sheet 7, and a diffusion film 8.

  The reflection film 2 is a rectangular film and has a function of reflecting light from the bottom surface of the light guide plate 4 to the light guide plate 4 side by the reflection surface 21. As the reflective film 2, an ESR (Enhanced Specular Reflector) having a high reflectance in the visible light range can be used due to a multilayer film structure using PET (Polyethylene Terephthalate) resin. As long as it can reflect, other materials may be used.

  The case frame 3 is formed in a frame shape to hold the side surface of the light guide plate 4. The case frame 3 is provided with a notch portion 31 into which the holding portion 4a protruding from the side surface of the light guide plate 4 is fitted in order to prevent the light guide plate 4 from being displaced.

  The light guide plate 4 is formed in a substantially rectangular shape, and light from the linear light source device 6 is incident from the side surface 4x facing the linear light source device 6 and is emitted from the main light emitting surface S as illumination light. It is a transparent or translucent plate-like body formed to a thickness of about 0.3 to 0.6 mm with an acrylic resin or a polycarbonate resin. The light guide plate 4 is formed of a first light guide plate 41 and a second light guide plate 42 as shown in FIG. 2 by dividing a single plate-like member into two so as to be line symmetric at the center. ing. On the side surfaces 41a, 42a facing each other when the first light guide plate 41 and the second light guide plate 42 face each other, a light shielding portion 43 formed by printing a coating material having a light shielding property is formed.

  If the light shielding portion 43 is provided on either one of the side surfaces 41a and 42a, the light leakage from the first light guide plate 41 is directed to the second light guide plate 42, whereas the light leakage from the second light guide plate 42 is the first. Although it is difficult for the light to enter the light guide plate 41, it is desirable that the light shielding portions 43 are provided on both the side surfaces 41a and 42a because the light can be more effectively prevented from entering each other. About light shielding, you may insert a plate-shaped member as a light-shielding part between side surface 41a, 42a. However, if the light shielding portion is a plate-like member, the plate-like member has a certain thickness, so that a bar-like dark portion is formed between the first light guide plate 41 and the second light guide plate 42. In the present embodiment, since the light shielding portion 43 is formed by printing a coating material having a light shielding property, the light shielding portion 43 can be formed much thinner than the plate-like member. Therefore, the light shielding portion 43 has the side surfaces 41a and 42a. Even if both are provided, it is possible to prevent a bar-like dark part from being formed between the first light guide plate 41 and the second light guide plate 42. Therefore, the side surfaces 41a and 42a of the first light guide plate 41 and the second light guide plate 42 can be arranged without a gap.

  Any coating material that can be fixed to the side surface 41a of the first light guide plate 41 and the side surface 42a of the second light guide plate 42 can be employed as the coating material having light shielding properties. The coating material may be black with high light shielding properties. However, if the coating material is white or reflective, the light from the first and second light guide plates 41 and 42 to the side surfaces 41a and 42a is reflected on the inner side surface of the light shielding portion 43, so This is desirable because the cutting efficiency of the light guide plates 41 and 42 can be increased.

  A fixing sheet 5 shown in FIG. 1 is a long tape for fixing the light guide plate 4 and the linear light source device 6 from below.

  As shown in FIG. 3, the linear light source device 6 is a light emitting device including a substrate 61, a light emitting element group 62, a reflecting portion 63, a resin sealing portion 64, and a printed wiring board 65.

  The substrate 61 is a wiring substrate in which a wiring pattern is formed on a rectangular bar-shaped insulating substrate. The insulating substrate can be formed of glass epoxy resin, BT resin (bismaleimide triazine resin thermosetting resin), or the like.

  The light emitting element groups 62 (A to F) are mounted at six locations as point light sources along the mounting surface of the substrate 61. The light emitting element group 62 is composed of three light emitting elements. The light-emitting element can be formed by stacking a semiconductor layer including a light-emitting layer over a conductive substrate formed using a semiconductor or an insulating substrate formed using sapphire or the like. The three light emitting elements that constitute the light emitting element group 62 emit red light, blue light, and green light, and can be combined to emit various colors. be able to.

  The reflection part 63 is formed by two members located on both sides of the light emitting element group 62. Each surface of the reflecting portion 63 facing the light emitting element group 62 reflects light from the light emitting element group 62 toward the light guide plate 4 (see FIG. 1), from the substrate 61 side toward the front side. It is an inclined surface where the interval gradually increases.

  The resin sealing portion 64 is obtained by sealing the light emitting element group 62 positioned between the reflecting portions 63 with an epoxy resin. In the linear light source device 6, a light source unit is configured by the light emitting element group 62 and the resin sealing unit 64. Six light source portions are provided on the substrate 61.

  The printed wiring board 65 is formed so as to protrude from the connecting portion 651 connected along the surface opposite to the mounting surface of the substrate 61, and a connector for supplying power is provided at the tip. The wiring portion 652 is formed of a flexible substrate having flexibility. The printed wiring board 65 is fixed to the board 61 by connecting the terminals formed in the connecting portion 651 to the electrodes provided on the board 61 by solder H.

  Here, the circuit of the linear light source device 6 will be described with reference to FIG. As described above, the light emitting element group 62 (the portion surrounded by the alternate long and short dash line) is composed of three light emitting elements R, G, and B, and the anodes thereof are connected by the wiring pattern L1 formed on the substrate 61. . The terminals T11 to T13 provided so as to correspond to the anodes of the respective light emitting element groups 62 by the printed wiring board 65 are connected to the terminal T14 by the wiring pattern L2. Further, the cathodes of the respective light emitting element groups 62 are connected to the terminals T311 to T363 by the wiring patterns L311 to L363 of the substrate 61, respectively. The terminals T311 to T363 are directly connected to the terminals T411 to T463 by the printed wiring board 65 through the wiring patterns L411 to L463.

  Since the circuit of the linear light source device 6 is configured in this way, a positive voltage is applied to the terminal T14 of the printed wiring board 65 on the mobile phone device body side, and the terminals T411 to T463 are individually set to the L level or the H level. By performing this control, it is possible to control the lighting and extinction of the light emitting element group 62 and the color.

  As shown in FIG. 1, the reflection sheet 7 is attached so as to straddle the light guide plate 4 along the substrate 61 of the linear light source device 6, so that the light from the light emitting element group 62 is directed toward the light guide plate 4. While reflecting, the linear light source device 6 and the light-guide plate 4 are fixed from the upper side.

  The diffusion film 8 is made of a polyester (PS) resin or a polycarbonate (PC) resin, and the surface thereof is formed on a rough surface like ground glass.

  The usage state of the backlight unit 1 according to the embodiment of the present invention configured as described above will be described with reference to the drawings.

  Although the light emitting element group 62 can individually control lighting and extinction and color control, in the present embodiment, the light emitting element groups A to C and the light emitting element groups D to F on the mobile phone device main body side. It is assumed that the control is divided into two groups.

  First, when the backlight unit 1 simply functions as an illuminating device that illuminates the display panel brightly, the light emitting elements R, G, and B of the light emitting element groups A to F are all lit to emit white light. The display content of the panel can be illuminated so as to be raised from the back side of the display panel.

  At this time, since the light-shielding portion 43 is formed thin by printing, the first light guide plate 41 and the second light guide plate 42 can be arranged without a gap, so that the boundary is not very noticeable for the observer. do not become.

  Next, a case where the first light guide plate 41 and the second light guide plate 42 emit light in different colors will be described. For example, the light emitting element groups A to C are controlled to emit red light, and the light emitting element groups D to F are controlled to emit blue light.

  The red light from the light emitting element groups A to C travels through the first light guide plate 41 and is emitted from the first light emitting surface S1 of the main light emitting surface S of the light guide plate 4. Since the light shielding portion 43 is provided on the side surface 41 a of the first light guide plate 41, it is possible to prevent the light guide portion 42 from entering the second light guide plate 42. Further, since the light shielding portion 43 is also provided on the side surface 42a of the second light guide plate 42, light leakage from the side surface 41a of the first light guide plate 41 can be blocked by the light shielding portion 43 of the side surface 42a.

  Further, the blue light from the light emitting element groups D to F travels through the second light guide plate 42 and is emitted from the second light emitting surface S2. Since the light shielding portion 43 is provided on the side surface 42 a of the second light guide plate 42, it is possible to prevent the light guide portion 41 from entering the first light guide plate 41. Further, since the light shielding portion 43 is also provided on the side surface 41a of the first light guide plate 41, light leakage on the side surface 42a of the second light guide plate 42 can be blocked by the light shielding portion 43 of the side surface 41a. Accordingly, it is possible to make the observer visually recognize the color boundary.

  As described above, the six light emitting element groups 62 arranged along the side surface of the light guide plate 4 simultaneously emit two colors, so that the first light guide plate 41 emits red light and at the same time the second light guide plate 42. Is emitting blue light, the display content on the first light-emitting surface S1 can be watched more closely than the display content on the second light-emitting surface S2. Further, since the viewer can enjoy two colors of light even when the display panel is not displayed, the aesthetics can be improved more than the light guide plate that emits only white light.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the embodiment. For example, although the light emitting element groups A to F of the linear light source device 6 are divided into two groups, it can be appropriately divided from three groups to six groups according to the number of light emitting element groups 62. In that case, the light guide plate 4 can also be divided according to the grouping of the light emitting element group 62. Moreover, although the case where the light emission color of the linear light source device 6 is a combination of red and blue has been described in the present embodiment, the same applies to other colors.

  In the present embodiment, the example in which the light source plate 4 is symmetrically divided into two parts by arranging the linear light source device 6 only on the side surface 4x of the light guide plate 4 has been described. It is also possible to arrange the light guide plate 4 into four crosses in a cross shape by arranging the four short sides and long sides in an L shape.

  The present invention is suitable not only for brightly illuminating the display panel from the back side but also for improving added value, and is therefore suitable for a backlight unit and a light guide plate that illuminate from the back side of the display panel.

1 is an exploded perspective view of a backlight unit according to an embodiment of the present invention. The perspective view of the light-guide plate used for the backlight unit shown in FIG. The perspective view of the linear light source device used for the backlight unit shown in FIG. Circuit diagram of the linear light source device shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Backlight unit 2 Reflective film 3 Case frame 4 Light guide plate 4x Side surface 5 Fixed sheet 6 Linear light source device 7 Reflective sheet 8 Diffusion film 21 Reflective surface 31 Notch part 41 First light guide plate 41a Side surface 42 Second light guide plate 42a Side surface 43 Light shielding part 61 Substrate 62 Light emitting element group 63 Reflecting part 64 Resin sealing part 65 Printed wiring board 651 Connection part 652 Wiring part R, B, G Light emitting element T11-T13, T14 Terminal T311-T313, T321-T323, T361-T363 Terminals T411 to T413, T421 to T423, T461 to T463 Terminals L1, L2, L311 to L313, L321 to L323, L361 to L363 Wiring patterns L411 to L413, L421 to L423, L461 to L463 Wiring patterns

Claims (7)

A light guide plate that illuminates the display panel from the back by emitting illumination light from the main light emitting surface;
And a light emitting device capable of simultaneously emitting n colors (where n is 2 or more and the number of the point light sources or less) by two or more point light sources arranged along the side surface of the light guide plate. The backlight unit. The backlight unit according to claim 1, wherein the light guide plate is divided corresponding to point light sources that emit light of different colors. The backlight unit according to claim 2, wherein a light-shielding portion is provided on side surfaces of the divided light guide plates facing each other. The backlight unit according to claim 3, wherein the light-shielding portion is formed by printing a coating material having a light-shielding property. Light from a light emitting device capable of emitting n colors (where n is 2 or more and not more than the number of point light sources) simultaneously from two or more point light sources is incident from one side surface, and is used as illumination light. A light guide plate that emits from the back and irradiates the display panel from the back,
The light guide plate is divided in accordance with the point light sources emitting light of different colors. The light guide plate according to claim 5, wherein light-shielding portions are provided on side surfaces facing each other by being divided. The light guide plate according to claim 6, wherein the light shielding portion is obtained by printing a coating material having a light shielding property.

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