JP2006244843A - Surface light source device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface light source device capable of emitting light with little nonuniform brightness, wherein there is no possibility that a pressure sensitive adhesive double-coated tape will adhere to a side surface of a light guide body, when the light guide body is fixed to a frame with the pressure sensitive adhesive double coated tape. <P>SOLUTION: This surface light source device is provided with the light guide body 6 having one main surface as an emitting surface 6a and a surface nearly orthogonal to the emitting surface 6a as an incidence surface, a light source, wherein the light-emitting surface is arranged to face the incidence surface of the light guide body 6, and a frame 3 holding the light source and the light guide body 6. The other principal surface of the light guide body 6 is fixed with the pressure sensitive adhesive double-coated tape 13 stuck to a fixing part 12 of the frame 3. The fixing part 12 of the frame 3 is provided with a surface 15b that is nonparallel to the other principal surface of the light guide body 6 and absorbing the displacement of the pressure sensitive adhesive double-coated tape 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a surface light source device suitable for a liquid crystal display device, for example.

  As is well known, a surface light source device using a cold cathode tube or a light emitting diode (LED) as a light source and a combination of the light source and a light guide is an OA device, an information terminal device, a personal computer, a television receiver, and the like. It is used as a lighting device in a liquid crystal display device. And there exist some which have a structure which demonstrates using FIG. 6 which shows the one part as a cross section in the surface light source device of such a use below, for example.

  That is, in FIG. 6, reference numeral 100 denotes a surface light source device, 101 denotes a frame-like frame constituting the surface light source device 100, and the upper surface (liquid crystal panel side) of the frame 101 is a light emitting surface 102a. A light guide body 102 having a light incident surface on a side surface (not shown) orthogonal to is held by being fixed by a double-sided adhesive tape 103. The frame 101 holds a light source (not shown) together with the light guide 102 so that its light emitting surface faces the incident surface of the light guide 102. Further, a plurality of optical sheets such as a diffusion sheet 104 and a prism sheet 105 are arranged on the upper surface of the light guide 102, and a reflection sheet 106 is provided on the lower surface (the side opposite to the liquid crystal panel). Yes.

  For fixing the light guide body 102 to the frame 101, first, a thin belt-like double-sided adhesive is provided on the shelf-like portion 107a of the fixing portion 107 having a substantially L-shaped cross section provided on the inner edge side of the frame 101. The tape 103 is pasted along the inner edge of the frame 101. Then, the wall portion 107b of the fixing portion 107 of the frame 101 is used for positioning, and the lower surface side on the opposite side surface 102b side opposite to the incident surface of the light guide 102 on the double-sided adhesive tape 103 attached to the fixing portion 107. The edge portion is pressed and fixed in an oblique direction, and then attached while pressing the incident surface side portion of the light guide 102 toward the frame 101, and the light guide 102 is fixed on the fixing portion 107 of the frame 101.

  By forming a condensing prism on the lower surface of the light guide 102, the number of optical sheets to be used is reduced, and the light guide 102 is not provided with a fixing projection that causes uneven brightness due to irregular reflection. In order to make the structure, the structure in which the light guide 102 is fixed to the frame 101 with the double-sided pressure-sensitive adhesive tape 103 is adapted to the recent reduction in thickness and weight of liquid crystal display devices.

  However, in the above prior art, when the light guide 102 is fixed to the frame 101, the double-sided adhesive tape 103 is moved by the pressing force and displaced from a predetermined position, or the double-sided adhesive tape 103 itself is crushed and displaced. It may happen. In such a case, a part of the double-sided adhesive tape 103 protrudes between the wall 107b of the fixing part 107 of the frame 101 and the opposite side surface 102b of the light guide 102, and further protrudes from the double-sided adhesive. The tape 103 may adhere and be fixed to the opposite side surface 102b of the light guide 102. In such a case, the light introduced from the light source to the light guide 102 hits the adhesive material of the double-sided adhesive tape 103 attached to the opposite side surface 102b and is irregularly reflected, and the irregularly reflected light is emitted from the emission surface 102a of the light guide 102. As a result, the light is not emitted uniformly, and in the liquid crystal display device, irregularly reflected light enters the display screen, resulting in uneven brightness, which may cause deterioration in display quality.

  The present invention has been made in view of the above situation, and the object of the present invention is to fix the light guide to the frame with the double-sided adhesive tape, and the double-sided adhesive tape adheres to the side surface of the light guide. The diffused light is not generated by the adhesive material of the double-sided adhesive tape, and uniform light can be emitted from the exit surface of the light guide. In the liquid crystal display device, there is no uneven brightness due to the diffusely reflected light. Another object of the present invention is to provide a surface light source device that does not cause a decrease in display quality.

The surface light source device of the present invention is
A light guide having one main surface as a light emission surface and a surface substantially orthogonal to the light emission surface as an incident surface, a light source disposed so that a light emitting surface faces the incident surface of the light guide, and the light source And a frame for holding the light guide, and a surface light source device in which the other main surface of the light guide is fixed to a double-sided adhesive tape affixed to the fixing portion of the frame, the fixing portion of the frame being double-sided adhesive It is characterized by comprising a displacement absorbing surface in which the adhesive surface for bonding the tape and the gap between the adhesive surface and the other main surface of the light guide are different,
Further, a light guide having one main surface as a light exit surface and a surface substantially orthogonal to the light exit surface as an incident surface, a light source disposed so that the light emitting surface faces the incident surface of the light guide, A surface light source device comprising a frame for holding the light source and the light guide, and having the other main surface of the light guide fixed to a double-sided adhesive tape affixed to the fixing portion of the frame. It is characterized by comprising at least two adhesive surfaces and a displacement absorbing surface of a double-sided pressure-sensitive adhesive tape that are parallel to the other main surface of the light guide and have different gap sizes formed between the other main surfaces. Is.

  As is clear from the above description, according to the present invention, when the light guide is fixed to the frame with the double-sided adhesive tape, it is possible to prevent the double-sided adhesive tape from protruding and adhering to the side surface of the light guide, This eliminates the generation of irregularly reflected light by the adhesive material of the double-sided adhesive tape, allows uniform light to be emitted from the exit surface of the light guide, and further eliminates uneven brightness due to irregularly reflected light in a liquid crystal display device. Thus, it is possible to prevent the display quality from being deteriorated.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, a first embodiment will be described with reference to FIGS. 1 is an exploded perspective view showing a configuration of the entire surface light source device, FIG. 2 is a cross-sectional view of the main part, FIG. 3 is a partially cutaway perspective view of the main part, and FIG. 4 is an outline of the liquid crystal display device. It is sectional drawing which shows a structure.

  1 to 4, a surface light source device 1 used for a liquid crystal display device 2 or the like includes a light source 5 using a cold cathode tube 4 on a substantially rectangular frame-shaped frame 3 formed using a synthetic resin or the like. And a substantially rectangular flat plate-shaped light guide body 6 having a predetermined thickness and formed of a translucent resin such as polycarbonate resin or acrylic resin. The light guide 6 has an upper surface (liquid crystal panel side) which is one main surface thereof as a light exit surface 6a, and a side surface orthogonal to the upper surface serves as a light entrance surface 6b. Although not shown, a large number of condensing prisms are formed on the lower surface of the other main surface that is the back surface (the side opposite to the liquid crystal panel). A plurality of optical sheets are disposed on the light exit surface 6 a of the light guide 6 from the diffusion sheet 7 and the prism sheet 8, and a reflection sheet 9 is disposed on the lower surface side of the light guide 6. ing.

  The cold cathode tube 4 of the light source 5 is attached to the frame 3 so as to be supported by the rubber holders 10 attached to both ends of the light guide 6 at a position facing the light incident surface 6b. The emitted light from the cold cathode tube 4 is directly incident on the light guide 6. Further, on the frame 3, a reflector 11 having a reflection surface having a substantially semicircular cross section constituting the light source 5 reflects the emitted light from the cold cathode tube 4, and the reflected light is incident on the light guide 6. It is attached close to the cold cathode tube 4 at a position opposite to the incident surface 6b side of the light guide 6 so as to face 6b.

  The frame 3 is provided with a fixing portion 12 having a substantially L-shaped cross section at least on the inner edge side portion of the frame member 3a on the opposite side surface 6c facing the incident surface 6b of the light guide 6. . The fixing portion 12 supports the light guide 6 at the opposite side surface 6c side portion with the double-sided adhesive tape 13 interposed therebetween, and supports the reflection sheet 9. The inward shelf-like portion 12a and the shelf It is comprised by the wall part 12b orthogonal to the shape part 12a.

  Further, the shelf-like portion 12a is formed with a step portion 14 for supporting the reflection sheet 9 at the top of the tip, and an adhesive for adhering the double-sided adhesive tape 13 to the upper portion from the step portion 14 to the wall portion 12b side. A surface portion 15 is provided. The bonding surface portion 15 includes a parallel bonding surface 15a parallel to the lower surface, which is the other main surface of the light guide 6 to be supported, and a single inclination angle connected to the parallel bonding surface 15a toward the wall portion 12b. The adhering surface portion 15 has a gap dimension between the opposing lower surface of the light guide 6 and the direction of the wall portion 12b of the fixed portion 12. The gaps are formed to have different sizes so as to expand. For example, the inclination of the displacement absorbing surface 15 b is such that the difference in height between the upper part and the lower part of the inclination is about the thickness of the double-sided adhesive tape 13. That is, for example, when the thickness of the double-sided pressure-sensitive adhesive tape 13 is about 0.1 mm to 0.15 mm, the height difference is about 0.1 mm to 0.2 mm.

  And about fixation of the light guide 6 to the flame | frame 3, first, both sides are sensitive on the parallel adhesion surface 15a of the shelf-like part 12a of the fixing | fixed part 12 provided in the inner edge side of the frame member 3a of the flame | frame 3. A thin belt-like double-sided adhesive tape 13 to which the pressure-sensitive adhesive is attached is attached in the longitudinal direction of the frame member 3a so as to be parallel to the surface of the wall 12b. Thereafter, the wall 12b of the fixing part 12 of the frame 3 is used for positioning such as abutting the opposing side surface 6c of the light guide 6, for example, on the double-sided adhesive tape 13 affixed to the parallel adhesive surface 15a of the shelf 12a. The lower surface edge portion of the light guide 6 on the opposite side surface 6c side is pressed and fixed in an oblique direction. Furthermore, the light guide 6 is attached to the incident surface 6 b side while being pressed in the direction of the frame 3, and the light guide 6 is fixed to the fixing portion 12 of the frame 3.

  Further, in the surface light source device 1 configured as described above, as shown in FIG. 4, a liquid crystal display element (liquid crystal panel) 17 is provided on the optical sheet 7 and the prism sheet 8 provided on the light guide 6. Is placed. Then, the outer cover 18 covers the liquid crystal display element 17 and the liquid crystal display device 2 by fitting and fixing the outer cover 18 and the frame 3 so as to fix the liquid crystal display element 17 and the surface light source device 1. Is configured.

  In the surface light source device 1 and the liquid crystal display device 2 thus configured, the light guide 6 is fixed to the frame 3 with the configuration of the surface light source device 1 as described above. The double-sided pressure-sensitive adhesive tape 13 is pressed by the light guide 6 when bonding the side surface 6 c side. When the light guide 6 is attached, the double-sided adhesive tape 13 is securely adhered to a predetermined position of the frame 3, and the insertion state of the light guide 6 is not fixed within a predetermined angle range. Can not be fixed. When these relations are lost, the double-sided pressure-sensitive adhesive tape 13 is displaced and displaced in the light guide insertion direction, or the double-sided pressure-sensitive adhesive tape 13 itself extends and deforms and displaces. 6 is about to protrude from the edge on the opposite side 6c side. However, the double-sided pressure-sensitive adhesive tape 13 extended and displaced in this way is displaced along the displacement absorbing surface 15b which is a downward inclined surface toward the edge direction which is the outer direction of the light guide 6. As a result, it is absorbed so as to be stored in the wedge-shaped gap formed by the displacement absorbing surface 15 b and the lower surface of the light guide 6. Therefore, the double-sided adhesive tape 13 does not protrude from the parallel adhesive surface 15a and adhere to the opposite side surface 6c of the light guide 6. Further, by providing the parallel adhesive surface 15a, not only the positioning of the double-sided pressure-sensitive adhesive tape 13 becomes easy, but also the adhesive strength of the light guide 6 can be made uniform, so that more reliable fixing can be performed. As a result, since the generation of irregularly reflected light generated by the adhesive material adhering to the opposite side surface 6c of the double-sided adhesive tape 13 is suppressed, uniform light with few spots is generated from the exit surface 6a of the light guide 6. Emitted.

  Further, in the liquid crystal display device 2, since the light emitted from the surface light source device 1 is uniform light with few spots, irregularly reflected light enters the display screen, resulting in uneven brightness and causing deterioration in display quality. There is no fear, and good quality can be displayed.

In the above embodiment, the adhesive surface 15 of the double-sided pressure-sensitive adhesive tape 13 provided on the fixing portion 12 of the frame 3 is composed of the parallel adhesive surface 15a and the displacement absorbing surface 15b. The main surface portion may be used as an adhesive surface, and the remaining portion may be used as a displacement absorbing surface. The displacement absorbing surface 15b also has a single inclination angle toward the outside of the light guide 6. For example, it may be formed as a curved surface that draws a curve. Further, it may be an inclined surface in which a plurality of inclinations having different inclination angles are combined, and an inclined surface in which the inclination angle continuously changes, or an inclined surface, a curved surface, a parallel surface, or the like may be used in appropriate combination.

  When the adhesive surface portion 15 is configured only from the inclined surface or the curved surface in this way, not only the formation of the adhesive surface portion 15 is facilitated, but the displacement portion of the double-sided pressure-sensitive adhesive tape 13 is continuously and smoothly moved to the displacement absorbing surface 15b side. Therefore, the displaced part of the displaced double-sided pressure-sensitive adhesive tape 13 can be absorbed more easily.

  Next, a second embodiment will be described with reference to FIG. FIG. 5 is a partially cutaway perspective view of the main part. Note that this embodiment differs from the first embodiment only in the configuration of the adhesive surface to which the double-sided pressure-sensitive adhesive tape provided at the fixing portion of the frame is bonded, and therefore, referring to FIGS. 1 to 4, The same parts are denoted by the same reference numerals, description thereof is omitted, and a configuration of the present embodiment that is different from the first embodiment will be described.

  In FIG. 5, a surface light source device 21 used for a liquid crystal display device or the like has a substantially rectangular frame-shaped frame 22 formed using a synthetic resin or the like. A fixing portion 23 having a substantially L-shaped cross section is provided on the inner edge side portion of the frame member 22a on the opposite side surface 6c facing the incident surface. The fixing portion 23 supports the light guide 6 at the opposite side surface 6c side portion with the double-sided adhesive tape 13 interposed therebetween, and supports the reflection sheet 9. The inward shelf-like portion 23a and the shelf It is comprised by the wall part 23b orthogonal to the shape part 23a.

  Further, the shelf-like portion 23a is formed with a step portion 14 for supporting the reflection sheet 9 at the upper end of the tip, and an adhesive for adhering the double-sided adhesive tape 13 to the upper portion from the step portion 14 to the wall portion 23b side. A surface portion 24 is provided. The adhesive surface portion 24 includes a parallel adhesive surface 24a parallel to the main surface of the light guide 6 to be supported, and a displacement absorbing surface 24b which is continuous to the parallel adhesive surface 24a and parallel to the wall portion 23b. It is formed to make. And the level | step difference of the parallel adhesion surface 24a and the displacement absorption surface 24b is a dimension which becomes the thickness grade of the double-sided adhesive tape 13 to adhere | attach. For example, when the thickness of the double-sided pressure-sensitive adhesive tape 13 is about 0.1 mm to 0.15 mm, the step size is about 0.1 mm to 0.2 mm.

  The light guide 6 is fixed to the frame 22 first on both sides of the parallel adhesive surface 24a of the shelf-like portion 23a of the fixing portion 23 provided on the inner edge side of the frame member 22a of the frame 22. A thin belt-like double-sided pressure-sensitive adhesive tape 13 to which the pressure-sensitive adhesive is attached is pasted in the longitudinal direction of the frame member 22a along the wall portion 23b. Thereafter, while using the wall portion 23b of the fixing portion 23 of the frame 22 for positioning, the lower surface edge portion on the opposite side surface 6c side of the light guide 6 is pressed and adhered onto the double-sided adhesive tape 13. Further, the incident surface side portion of the light guide 6 is attached to the frame 22 to fix the light guide 6.

  In the surface light source device 21 configured as described above, a liquid crystal display element is disposed on the light guide 6 as in the first embodiment. The outer cover covers the liquid crystal display element and is provided so as to fix the liquid crystal display element and the surface light source device 21 to constitute a liquid crystal display device.

  In the surface light source device 21 and the liquid crystal display device configured as described above, the structure of the surface light source device 21 is the same as described above, and the light guide 6 is fixed to the frame 22. The double-sided pressure-sensitive adhesive tape 13 is displaced along the displacement absorbing surface 24b whose gap dimension is increased toward the edge direction, which is the outer direction of the light guide 6, so that the bottom surface of the light guide 6 and the displacement absorption. It will be absorbed so that it may be stored in the gap formed by the surface 24 b, and the protruding double-sided adhesive tape 13 portion will not adhere to the opposing side surface 6 c of the light guide 6. In addition, the parallel adhesive surface 24a facilitates the positioning of the double-sided pressure-sensitive adhesive tape 13 and the adhesive strength is made uniform, and the displacement absorbing surface 24b is formed by providing a level difference. Since it is attracted to the lower side at a stretch, it is possible to reduce the possibility of the displacement portion adhering to the opposite side surface 6c side of the light guide 6 more. As a result, in the same manner as in the first embodiment, since the generation of irregularly reflected light generated by the adhesive material attached to the opposite side surface 6c of the double-sided adhesive tape 13 is suppressed, the light exiting surface 6a of the light guide 6 , Uniform light with few spots is emitted.

  Further, in the liquid crystal display device, the light emitted from the surface light source device 21 is uniform light with few spots, so that irregularly reflected light may enter the display screen, resulting in uneven brightness and a reduction in display quality. The display of good quality can be performed.

  In the above embodiment, the adhesive surface portion 24 of the double-sided pressure-sensitive adhesive tape 13 provided on the fixing portion 23 of the frame 22 is configured by the parallel adhesive surface 24a having a step and the displacement absorbing surface 24b. You may comprise by many parallel planes which have a level | step difference in this. Further, the adhesive surface portion 24 of the double-sided pressure-sensitive adhesive tape 13 is bonded in parallel with a step between them so that the gap between the lower surface of the light guide body 6 and the adhesive surface portion 24 increases toward the edge of the light guide body 6. A combination of the surface and the displacement absorbing surface shown in the first embodiment may be used.

1 is an exploded perspective view showing a first embodiment of the present invention. It is sectional drawing of the principal part in the 1st Embodiment of this invention. It is a partially cutaway perspective view of the principal part in the 1st Embodiment of this invention. It is sectional drawing which shows schematic structure of the liquid crystal display device which concerns on the 1st Embodiment of this invention. It is a partially cutaway perspective view of the principal part in the 2nd Embodiment of this invention. It is sectional drawing which shows the fixing | fixed part of the flame | frame and light guide of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3,22 ... Frame 5 ... Light source 6 ... Light guide 6a ... Outgoing surface 6b ... Incident surface 12, 23 ... Fixed part 13 ... Double-sided adhesive tape 15, 24 ... Adhesive surface part 15a ... Adhesive surface 15b ... Displacement absorption surface 24a ... Parallel Adhesive surface 24b Displacement absorbing surface

Claims (5)

  A light guide having one main surface as a light emission surface and a surface substantially orthogonal to the light emission surface as an incident surface, a light source disposed so that a light emitting surface faces the incident surface of the light guide, and the light source And a frame for holding the light guide, and a surface light source device in which the other main surface of the light guide is fixed to a double-sided adhesive tape affixed to the fixing portion of the frame, wherein the frame fixing portion Is provided with an adhesive surface portion including an adhesive surface to which the double-sided pressure-sensitive adhesive tape is bonded, and a displacement absorbing surface that makes the gap between the adhesive surface and the other main surface of the light guide different. Surface light source device.   The surface light source device according to claim 1, wherein the bonding surface portion is an inclined surface or a curved surface in which the gap dimension gradually increases toward the outside of the light guide.   The surface light source device according to claim 1, wherein the bonding surface portion includes a plurality of inclined surfaces having different inclination angles.   The adhesive surface portion is composed of an adhesive surface parallel to the other main surface and a displacement absorbing surface formed by providing a step with the adhesive surface, and the gap dimension is larger as it goes outward of the light guide. The surface light source device according to claim 1, wherein the surface light source device is arranged as follows.   3. The surface light source device according to claim 1, wherein the adhesive surface portion is configured by an adhesive surface parallel to the other main surface and a displacement absorbing surface including the inclined surface or the curved surface.

Images