JP2010251021A - Lighting system and display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat lighting system preventing bright line or dark line from being generated at a joint between light guide plates in the flat lighting system including a plurality of light guide plates disposed in a planar manner. <P>SOLUTION: A resin structure is disposed to cover a joint of a plurality of light guide plates disposed adjacently to each other. Accordingly, the light emitted through the joint of the adjacent light guide plates is introduced into the resin structure, and the introduced light is totally reflected within the resin structure and returned to the light guide body, whereby the bright line generated at the joint of light guide plates is suppressed. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an illuminating device that illuminates a non-self-luminous display element and a display device used in electronic equipment, and more particularly to a liquid crystal display device such as a computer monitor or a liquid crystal television.

  Liquid crystal display devices in which a flat illumination device is provided on the back surface of a liquid crystal display panel are widely used. In recent years, liquid crystal display devices have been increased in size, and flat type illumination devices used therefor are also required to be increased in size. In general, the risk of generating defective products increases with the increase in size of optical members, and the cost of equipment also increases. Therefore, a method of regularly arranging a plurality of light guide plates to form a light guide having a large light emission area is employed. When this method is used, when the light guide plate is damaged or poorly formed, only the corresponding light guide plate needs to be replaced, so that the defect cost can be suppressed. Moreover, since a molded product becomes small, the increase in equipment cost can be suppressed.

  However, when a plurality of light guide plates are regularly arranged to increase the light emitting area, the joints between adjacent light guide plates are considered in consideration of variations in molded products, interference during assembly, and expansion of the light guide plate due to heat generated by the light source. It is necessary to provide a gap. In general, in a lighting device, when light from a light source is incident on a light guide plate, not all of the light is emitted as illumination light from the upper surface or the lower surface of the light guide plate, and a part of the light is also emitted from a side surface other than the incident surface. The Therefore, if there is a gap at the joint between adjacent light guide plates, the light emitted from these side faces exits from above the gap while repeating reflection between the side surfaces of the light guide plates facing each other at the joint. Appears as a bright line at the joint. At the joints of the light guide plates, strong light is emitted from a very narrow range, so that even if light is scattered using a diffuser plate or the like, a wide bright line appears. In addition, if the structure of the light guide plate is devised to prevent bright lines and light emitted from the side surfaces of each light guide plate is suppressed, a dark line is generated at the joint of the light guide plates.

  As described above, when a plurality of light guide plates are arranged adjacent to each other, if there is a gap (a joint here) between the light guide plates, strong light leaks from the gap. If adjacent light guide plates are optically bonded, light will not leak from the joints of the light guide plates. For example, even if a plurality of light guide plates are arranged in close contact, a minute gap is partially formed. It is not possible to prevent light from leaking from the gap.

  In order to solve this problem, a film in which a member for adjusting the transmittance is unevenly arranged is provided on the upper part of the light guide (see, for example, Patent Document 1), or an air layer is provided on the upper part of the light guide. Etc. are known (see, for example, Patent Document 2).

JP 2007-194199 A (page 5-6, FIG. 1) JP 2006-235249 A (2nd page, FIG. 2)

  However, when the method of Patent Document 1 is used, the film also affects the region other than the bright line generation portion at the joint of the light guide plates, which causes a problem of overall luminance reduction. . Further, when the air layer is expanded until the bright line is not visible using the method of Patent Document 2, there is a problem that the thickness of the entire flat illumination device becomes excessively thick.

  Therefore, in the present invention, in a lighting device having a structure in which a plurality of light guide plates are combined, bright lines generated at the joints of the light guide plates are generated without causing a decrease in overall brightness and without excessively increasing the thickness of the lighting device. The purpose is to suppress. That is, in the lighting device of the present invention, the resin structure is arranged so as to cover only the periphery of the joints of the light guide plates arranged adjacent to each other. Thereby, the light emitted from the joint of the light guide plates can be reflected inside the resin structure and returned to the light guide.

  Furthermore, the resin structure is disposed on the irradiation surface of the light guide so that the longitudinal direction of the resin structure and the traveling direction of light from the light source are perpendicular to each other.

  Further, this resin structure has at least one apex angle formed by two inclined surfaces.

  Furthermore, the irradiation surface of each light guide plate is covered with the resin structure within a range of 5 mm from the end portion constituting the joint. Thereby, it can prevent that illumination light interferes with a resin structure.

  The display device of the present invention includes a lighting device in which a resin structure is disposed so as to cover only the periphery of joints between a plurality of light guide plates disposed adjacent to each other, and a display element provided on the upper surface of the lighting device It has. At the joints of the light guide plates, the opposing light guide plates are arranged adjacent to each other with a gap therebetween. And much of the light emitted from the joint of the light guide plates is totally reflected inside the resin structure and returns to the light guide. For this reason, generation of bright lines is eliminated, and uniform display can be realized.

  According to the present invention, light emitted from joints between a plurality of light guide plates arranged adjacent to each other is introduced into a resin structure disposed so as to cover the joints, and is totally reflected in the resin structure to guide light. Since it returns to the body, generation of bright lines is suppressed, and a uniform light emitting surface can be realized.

It is a figure which shows typically the cross section of the flat type illuminating device of this invention. It is a perspective view which shows the light-guide plate and resin structure of the flat illuminating device of FIG. It is a figure which shows the cross-sectional shape example of a resin structure.

  In the illumination device of the present invention, a plurality of light guide plates are arranged adjacent to each other in a planar shape to constitute a light guide. A light source is disposed on the outer surface of the light guide. And the resin structure is arrange | positioned so that the joint of these some light-guide plates may be covered. The resin structure has a function of transmitting a part of the light incident on the resin structure from the light guide side and totally reflecting the light and re-entering the light guide. With such a configuration, light emitted from a joint between adjacent light guide plates is introduced into the resin structure, and most of the introduced light is totally reflected inside the resin structure and returns to the light guide plate. . Thereby, the bright line which generate | occur | produces in the joint of a light-guide plate can be suppressed.

  The resin structure is arranged so that the longitudinal direction of the resin structure is perpendicular to the traveling direction of light from the light source. Furthermore, it is desirable that the resin structure covers a range of 5 mm or less from the joint (the end of the light guide plate).

  The display device of the present invention has a configuration in which a display element is arranged on the upper surface of the lighting device having the above-described configuration. Therefore, most of the light emitted from the joint of the light guide plates is totally reflected inside the resin structure and returns to the light guide. For this reason, bright lines generated on the display screen are eliminated, and uniform display can be realized.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the flat illumination device of this embodiment, a plurality of light guide plates are arranged adjacent to each other in a planar shape. FIG. 2 is a perspective view showing a state in which four light guide plates 6a, 6b, 6c and 6d are arranged adjacent to each other and the resin structure 7 is arranged at the joint. The resin structure 7 is disposed so as to cover the joint between the light guide plate 6a and the light guide plate 6b and the joint between the light guide plate 6c and the light guide plate 6d. At this time, the resin structure 7 is disposed so that the longitudinal direction of the resin structure is perpendicular to the traveling direction of light from the light source. FIG. 1 schematically shows a cross-sectional configuration of the flat illumination device of the present embodiment. In addition, although the cross-sectional structure concerning the light-guide plate 6a and the light-guide plate 6b is shown in FIG. 1, it becomes the same structure also about the other light-guide plate 6c and light-guide plate 6d which comprise the light guide body of a planar illuminating device. Yes.

  As shown in FIG. 1, the light guide plate 6a and the light guide plate 6b adjacent to each other are arranged so that the end surface 8a and the end surface 8b face each other, and a minute gap is provided between the end surface 8a and the end surface 8b which are joints. Is provided. The light sources 2 are respectively provided outside the light guide plate 6a and the light guide plate 6b arranged in this manner. The light emitting surface of the light source 2 is opposed to the incident surface 11a of the light guide plate 6a and the incident surface 11b of the light guide plate 6b. Although not shown, a plurality of light sources 2 are provided as point light sources, and are arranged on a straight line parallel to each incident surface.

  When the light emitted from the light source 2 is respectively incident from the incident surface 11a and the incident surface 11b, most of the light is emitted as illumination light from the irradiation surface 12a and the irradiation surface 12b. The light propagates through 6a and the light guide plate 6b, and is emitted from an end surface 8a opposite to the incident surface 11a and an end surface 8b opposite to the incident surface 11b. Note that each surface of the light guide plate including the incident surface and the irradiation surface is subjected to processing for uniformly emitting light from the irradiation surface. Further, in order to improve the optical characteristics of the flat illumination device, the reflection film 3 is provided on the lower surface side of the light guide, and the diffusion film 4 and the prism sheet 5 are disposed on the irradiation surface side.

  Between the diffusion film 4 and the irradiation surface of the light guide plate, a resin structure 7 is provided so as to cover joint portions of a plurality of light guide plates arranged adjacent to each other. The resin structure 7 is a polyhedron having an inclined surface 9a, an inclined surface 9b, and an apex angle 10 formed by the inclined surface 9a and the inclined surface 9b. The range in which the irradiation surface of each light guide plate is covered by the resin structure 7 is desirably within 5 mm from the end of the light guide plate toward the incident surface. When this range is larger than 5 mm, the illumination light emitted from the irradiation surface of each light guide plate is interfered by the resin structure 7, so that uniform surface light emission of the flat illumination device is hindered.

  With such a configuration, light emitted from the end face of each light guide plate at the joint of the plurality of light guide plates enters the upper resin structure 7 while being repeatedly reflected in the gap between the end faces of the other light guide plates facing each other. Shine. Furthermore, the light that has entered the resin structure 7 is reflected by the inclined surfaces 9a and 9b and is returned to the inside of each light guide plate again. In this way, the flat illumination device of the present invention can return most of the light emitted from the joints between the adjacent light guide plates to the inside of the light guide plate and suppress the bright lines generated at the joints.

  The shape of the resin structure 7 is not limited to the polyhedron described above, and may be the shape shown in FIG. As shown in FIG. 3A, the upper surface may be semicircular. By making the semicircular shape, when the angular distribution of the light emitted from the joint between the light guide plate 6a and the light guide plate 6b is large, the efficiency of totally reflecting the light to the light guide plate can be increased.

  Moreover, as shown in FIG.3 (b), you may provide multiple combinations of the inclined surface 9a in the upper part, the inclined surface 9b, and the apex angle 10. FIG. With such a configuration, the height from the bottom surface of the resin structure 7 to the apex angle 10 can be suppressed, and the resin structure 7 can be made thin. At this time, the inclined surface 9a and the inclined surface 9b may have different inclination angles with respect to the horizontal plane. By optimizing the inclination angle of the inclined surface 9 in accordance with the direction of light incident on the resin structure 7, the effect of suppressing the bright line can be improved.

  As shown in FIG. 3C, a lower protrusion 13 having a height lower than the thickness of the light guide plate may be provided at the lower portion of the resin structure 7. By inserting the lower protrusion 13 between the two adjacent light guide plates 6a and 6b, the resin structure 7 can be prevented from being displaced. Moreover, the light emitted from the end surfaces of the light guide plate 6 a and the light guide plate 6 b can be efficiently introduced into the resin structure 7.

  In this embodiment, a plurality of point light sources are arranged in a line, but a line light source may be used as the light source. In addition, a light emitting diode, EL, or other small light emitting source can be used as a light source used in the flat illumination device. In addition, as a material for the light guide plate and the resin structure, an inorganic material such as polycarbonate resin, acrylic resin, other transparent synthetic resin, or glass can be used.

DESCRIPTION OF SYMBOLS 1 Flat illumination device 2 Light source 3 Reflective film 4 Diffusion film 5 Prism sheet 6a, 6b, 6c, 6d Light guide plate 7 Resin structure 8a, 8b End surface 9a, 9b Inclined surface 10 Vertical angle 11a, 11b Incident surface 12a, 12b Outgoing Surface 13 Lower projection

Claims (8)

A light guide having a configuration in which a plurality of light guide plates are arranged adjacent to each other;
A light source disposed opposite two side surfaces parallel to each other of the outer surface of the light guide;
A resin structure disposed on joints of the plurality of light guide plates,
The resin structure is a lighting device, wherein a part of the light emitted from the joint is totally reflected to re-enter the light guide and part of the light is transmitted.   The lighting device according to claim 1, wherein the resin structure is arranged so that a longitudinal direction of the resin structure is perpendicular to a traveling direction of light from the light source.   The lighting device according to claim 1, wherein the resin structure includes at least one apex angle formed by two inclined surfaces.   The lighting device according to claim 1, wherein the resin structure has a semicircular cross section.   The said resin structure is provided with a projection part thinner than the thickness of the said light-guide plate in the lower part, The said projection part is inserted in the clearance gap between the said joints, The Claim 1 characterized by the above-mentioned. Lighting equipment. Each of the plurality of light guide plates has an irradiation surface for emitting illumination light on the upper surface,
The lighting device according to any one of claims 1 to 5, wherein a range of 5 mm or less from an end of the irradiation surface is covered with the resin structure.   The illumination device according to claim 1, wherein the light sources are a plurality of point light sources, and are arranged on a straight line parallel to the two side surfaces. A light guide having a configuration in which a plurality of light guide plates are arranged adjacent to each other;
A light source disposed facing two side surfaces parallel to each other of the outer surface of the light guide;
A resin structure disposed on a joint of the plurality of light guide plates;
A display element provided on the upper surface of the light guide,
The display device according to claim 1, wherein the resin structure totally reflects a part of the light emitted from the joint and re-enters the light guide and transmits a part thereof.

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