JP2014026920A - Planar lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a planar lighting device which facilitates narrow framing of a planar lighting device and reliably performs the positioning of an optical sheet in the planar lighting device.SOLUTION: A protrusion part 18bA protruded to an inner circumferential surface of a frame 16 is formed on an edge part 18b of an opposite surface side to an incident surface of a light guide sheet of an optical sheet 18. The protrusion part 18bA is arranged in a recessed part so as to be engaged with the recessed part 16dA formed on an opposite portion to the protrusion part 18bA of the frame 16 and, thereby, the positioning of the optical sheet 18 with respect to the frame 16 is performed. Thus, the recessed part 18bA is formed on a part related to the edge part of the opposite surface side to the incident surface of the light guide sheet of the frame 16, therefore, there is no necessity of forming a recessed part, in particular, on a part extended in a direction vertical to the incident surface of the light guide sheet of the frame 16 and the narrow framing of the part can be facilitated.

Description

The present invention relates to a planar illumination device used as illumination means such as a liquid crystal display device.

Nowadays, liquid crystal display devices are generally used as display devices for electronic devices such as personal computers and mobile phones. Since liquid crystal is not a self-luminous display element, for example, in a transmissive liquid crystal display device, illumination means for irradiating light to the liquid crystal panel is essential, and a transflective liquid crystal display device using external light However, auxiliary lighting means are provided to enable use in the dark. As an illuminating means of such a liquid crystal display device, a planar illuminating device having a light guide plate and a light source disposed on the side of the light guide plate as main components has an advantage that it can be easily reduced in thickness. Therefore, it is widely used in combination with liquid crystal display devices. In addition, with the recent improvement in performance of white light emitting diodes (LEDs), a planar lighting device using a white LED as a light source is generally used in order to further reduce the size and thickness of the planar lighting device and reduce power consumption. It has become.

An example of a display device provided with such a planar illumination device is shown in FIG. In FIG. 7, the display device 100 includes a liquid crystal display panel (LCD) 110 including a pair of glass substrates 112 and a polarizing plate 114, and one (front surface) of a pair of opposing main surfaces disposed on the back side of the LCD 110. A light guide plate 116 serving as a light exit surface, a reflection sheet 118 disposed on the back side of the light guide plate 116, and a plurality of layers (four layers in the example of FIG. 7) disposed between the LCD 110 and the light guide plate 116. A plurality of plate-like (or sheet-like) members such as the sheet 120 are included as constituent elements. These structural elements are formed in a frame shape of a frame 124 made of a synthetic resin material together with a point light source 122 such as a white LED arranged facing the light incident surface 116a (FIG. 7C) of the light guide plate 116. It is stored inside and configured as an integrated display device 100.

In the display device 100 having such a configuration, the LCD 110 is fixed to a mounting seat 124a formed so as to protrude inside the frame 124 via a double-sided tape 126 (FIG. 7B). . The optical sheet 120 includes, for example, a diffusion sheet, a prism sheet, and the like, and is fixed to the mounting seat 124 a of the frame 124 via the double-sided tape 126, as with the LCD 110. Further, the reflection sheet 118 is also fixed by a double-sided tape 127 to a mounting seat 124 b formed so as to protrude inside the frame 124. Further, a light shielding member 128 that covers the point light source 122 and the light incident surface 116a (FIG. 7C) of the light guide plate 116 is disposed. In FIG. 7C, reference numeral 130 denotes a double-sided tape, and reference numeral 132 denotes a wiring board of a point light source. (For example, refer to Patent Document 1).
Further, in order to ensure the positioning of the optical sheet 120, a tab as shown in FIG. 6A is provided on the end of the optical sheet 120 that is orthogonal to the end on the side where the point light source 122 is disposed. 120a is formed, and a recessed portion 124c having a complementary shape for receiving the tab 120a is formed at a corresponding position of the frame 124. Therefore, as shown in FIG. 6A, the optical sheet 120 has an arrow A direction orthogonal to the frame 124 (a direction orthogonal to the light incident surface 116 a of the light guide plate 116) and a B direction ( Positioning in a direction parallel to the light incident surface 116a of the light guide plate 116 is performed (see, for example, Patent Documents 2 and 3).

JP 2010-224000 A JP 2009-265237 A JP 2006-154320 A

As described above, the display device 100 has a structure in which necessary components are integrally held and necessary strength is secured by the frame 124 arranged so as to surround the LCD 110 in a frame shape. By the way, not only from the viewpoint of functionality such as miniaturization of the display device 100 but also from the viewpoint of design, a narrow frame for the display device 100 is always required. In order to promote this narrowing of the frame, when the thickness of the frame 124 (thickness in the direction of arrow B in FIG. 6A) is reduced, a recess 124c for receiving the tab 120a of the optical sheet 120 is secured. It becomes difficult. And since there exists a possibility that the positioning of the optical sheet 120 may become inadequate, it is an obstacle in satisfy | filling the request | requirement of the narrow frame of the display apparatus 100. FIG.
The present invention has been made in view of the above problems, and the object of the present invention is to further narrow the frame of the planar lighting device, in particular, at least a frame extending in a direction orthogonal to the light incident surface of the light guide plate. An object of the present invention is to promote narrowing of the frame and to reliably position the optical sheet in the planar illumination device.

(Aspect of the Invention)
The following aspects of the present invention exemplify the configuration of the present invention, and will be described separately for easy understanding of various configurations of the present invention. Each section does not limit the technical scope of the present invention, and some of the components of each section are replaced, deleted, or further while referring to the best mode for carrying out the invention. Those to which the above components are added can also be included in the technical scope of the present invention.

(1) A light guide plate having one of a pair of opposed main surfaces as a light exit surface, at least one optical sheet stacked on the exit surface, and a light shielding member that defines an effective area of the exit surface A planar illumination device including a light source disposed opposite to a light incident surface of the light guide plate and a frame for housing these components, wherein the optical sheet is light incident on the light guide plate. A convex portion that protrudes toward the inner peripheral surface of the frame is formed at an edge portion of the surface facing the surface, and a concave portion in which the convex portion is disposed at a portion facing the convex portion of the frame. A planar lighting device formed (Claim 1).
In the planar illumination device described in this section, a convex portion that protrudes toward the inner peripheral surface of the frame is formed at the edge of the optical sheet on the side facing the light incident surface of the light guide plate. is there. And this convex part is positioned in a recessed part so that it may engage with the recessed part formed in the site | part facing the convex part of a flame | frame, and the positioning of an optical sheet with respect to a flame | frame is made | formed. According to this configuration, the concave portion is formed in a portion of the frame that is related to the edge portion on the surface facing the light incident surface of the light guide plate, and the convex portion and the concave portion have a function of positioning the optical sheet and the frame. In particular, it is not necessary to form a recess in a portion extending in a direction perpendicular to the light incident surface of the light guide plate of the frame, and this facilitates narrowing of the frame.

(2) In the above item (1), the convex portion of the optical sheet has a widened portion with at least a distal end portion extending in a surface direction of the optical sheet as compared with a base end portion, and is formed in the concave portion of the frame. A planar illumination device having a widened portion having a complementary relationship with the widened portion of the convex portion (Claim 2).
The planar illumination device described in this section includes a widened portion in which at least a tip portion of the convex portion of the optical sheet extends in the surface direction of the optical sheet as compared to a base end portion, and a convex portion of the concave portion of the frame. The widened portion having a complementary relationship with the widened portion constitutes a so-called undercut structure that restricts relative movement in the direction in which the optical sheet is separated from the frame. The undercut structure enhances the positioning function between the frame and the optical sheet.

(3) In the above items (1) and (2), the convex portion of the optical sheet and the concave portion of the frame are provided in two or more locations, and at least one of them has a shape different from the other locations. A planar lighting device (claim 3).
In the planar illumination device described in this section, the convex portion of the optical sheet and the concave portion of the frame are provided at two or more locations, and the convex portion and the concave portion at each location have a function of positioning the optical sheet and the frame. It is something that demonstrates. Moreover, at least one convex portion having a shape different from that of other portions functions as a front / back / upper / lower discrimination means of the optical sheet.

(4) In the above item (3), a planar illumination device in which a notch shape is formed in at least one convex portion having a shape different from that of the other portion of the optical sheet (claim 4). .
The planar illumination device described in this section can be used to discriminate the front, back, top and bottom of the optical sheet by the notch shape formed in at least one convex portion having a shape different from that of other portions of the optical sheet. Is to do.
(5) The planar illumination device according to (4), wherein a convex shape corresponding to a notch shape of the convex portion of the optical sheet is formed in the corresponding concave portion of the frame.
The planar illumination device described in this section further enhances the positioning function between the frame and the optical sheet by the engagement of the notch shape and the convex shape.

(6) In the above paragraphs (1) to (5), the position of the edge portion on the light incident surface side of the light guide plate as the optical sheet is provided with a plurality of the optical sheets and the number of stacked layers counted from the exit surface is higher. Is formed so as to be separated from the light incident surface of the light guide plate, and the light shielding member extends from the light incident surface side of the light guide plate so as to cover the vicinity of each edge portion of the plurality of optical sheets. A planar illumination device fixed to each optical sheet (Claim 5).
When the planar lighting device described in this section includes a plurality of optical sheets, the position of the edge portion on the light incident surface side of the light guide plate is more guided as the optical sheet is higher in the stacking step counted from the exit surface. By being formed so as to be separated from the light incident surface of the light plate, the edge of the light incident surface side of the light guide plate of each optical sheet is arranged in the upper stage in a mode in which the light emission surface of the light guide plate is viewed in plan view. It is exposed without being covered by the positioned optical sheet. The light shielding member extends from the light incident surface side of the light guide plate so as to cover the vicinity of the edge portions of the plurality of optical sheets at the exposed edge portions of the optical sheets. The exposed part in the vicinity of the edge part is fixed by the light shielding member. For example, a double-sided tape or an adhesive is used for fixing the light shielding member to each optical sheet.

(7) In the above item (6), the thickness between the pair of opposing main surfaces is set to the center portion of the light guide plate within a range of a predetermined width near the center portion from the light incident surface of the exit surface of the light guide plate. An inclined surface that is thinner toward the center is formed, the range closer to the center than the inclined surface has a constant thickness, and from the edge of the light guide plate on the light incident surface side of the plurality of optical sheets A planar illumination device in which a range of a predetermined width is inclined following an inclined surface formed on an emission surface of the light guide plate (Claim 6).
In the planar illumination device described in this section, the range of a predetermined width from the edge of the light guide plate on the light incident surface side of the plurality of optical sheets is inclined following the inclined surface formed on the light exit surface of the light guide plate. By doing so, the light shielding member extending from the light incident surface side of the light guide plate so as to cover the vicinity of each edge portion of the plurality of optical sheets is fixed along the inclined surface of each optical sheet. This prevents a steep bent portion from being formed on the light shielding member extending from the light incident surface side of the light guide plate, and sufficiently secures the fixing strength of the light shielding member with respect to each optical sheet.

(8) In the above item (7), the optical sheet in which the stacking stage counted from the emission surface is positioned at the uppermost stage among the plurality of optical sheets does not hit the inclined surface of the optical sheet positioned at the lower stage. A planar illumination device arranged in parallel with an emission surface of a portion having a certain thickness of the light guide plate (Claim 7).
In the planar illumination device described in this section, the optical sheet in which the stacking step counted from the exit surface is positioned at the uppermost stage is arranged in parallel with the exit surface of the constant thickness portion of the light guide plate. The vicinity of the front end portion of the light shielding member extending so as to cover the vicinity of each edge portion of the plurality of optical sheets from the light incident surface side of the light plate is also parallel to the light exit surface of the light guide plate on the optical sheet located at the uppermost stage. Will be placed. Then, the object to be illuminated is stabilized by mounting an object to be illuminated such as a polarizing film of an LCD on the surface of the light shielding member parallel to the exit surface of the light guide plate.

(9) In the above item (8), among the plurality of optical sheets, the guide of the optical sheet positioned on the top of the optical sheet in which the stacking level counted from the exit surface is positioned at the uppermost level and the optical sheet positioned immediately below it is provided. A planar illumination device in which positions in the stacking direction of the plurality of optical sheets coincide with or substantially coincide with the upper edge of the edge on the light incident surface side of the optical plate (Claim 8).
The planar illuminating device described in this section includes an optical surface between the upper surface of the optical sheet positioned at the uppermost stage and the upper edge of the edge of the light guide plate on the light incident surface side of the optical sheet positioned immediately below the optical sheet. When the positions in the sheet stacking direction match or substantially match, the position in the vicinity of the tip of the light shielding member in the optical sheet stacking direction is arranged in parallel with the exit surface of the light guide plate. . That is, the vicinity of the tip of the light shielding member is related not only to the upper surface of the optical sheet positioned at the uppermost stage but also to the upper edge of the edge of the optical sheet positioned immediately below the optical sheet in the stacking direction of the plurality of optical sheets. By being supported in a manner in which the positions match or substantially match, the vicinity of the tip of the light shielding member is stably supported over a wider range and parallel to the exit surface of the light guide plate. In this description, the term “substantially coincidence” is intended to allow inconsistencies within an allowable range from the viewpoint of dimensional accuracy and assembly accuracy of each component.

(10) In the above items (7) to (9), of the plurality of optical sheets, an end of the optical sheet on which the laminated stage counted from the exit surface is positioned at the lowest stage is on the light incident surface side of the light guide plate The position related to the stacking direction of the plurality of optical sheets on the upper edge of the edge on the light incident surface side of the light guide plate of the optical sheet located immediately above the upper edge of the edge is downward. A planar illumination device located (claim 9).
The planar illumination device described in this section is positioned immediately above the upper edge of the edge on the light incident surface side of the light guide plate of the optical sheet in which the stacking step counted from the exit surface is located at the lowest step. The position of the upper edge of the edge of the light guide plate on the light incident surface side of the optical sheet that is related to the stacking direction of the plurality of optical sheets is located below, so that the light guide plate can be viewed from the light incident surface side of the light guide plate. The light shielding member extending so as to cover the vicinity of each edge portion of the plurality of optical sheets constitutes an inclined surface following the inclined surface of the optical sheet in which the stacking steps counted from the emission surface are positioned at the lowest level. Then, the inclined surface of the light shielding member is maintained from the optical sheet positioned at the lowest level to the position where the light shielding member rides over the optical sheet positioned immediately above it. This prevents a steep bent portion from being formed on the light shielding member, and sufficiently secures the fixing strength of the light shielding member with respect to each optical sheet.

(11) In the above items (6) to (10), the plurality of optical sheets are laminated on the first sheet and the first sheet having the first laminated stage counted from the light exit surface of the light guide plate. A planar lighting device including a second sheet and a third sheet laminated on the second sheet (claim 10).
In the planar illumination device described in this section, the plurality of optical sheets stacked and arranged on the light exit surface of the light guide plate includes a first sheet, a second sheet, and a third sheet. To (10).

(12) A light guide plate having one of a pair of opposing main surfaces as a light exit surface, at least one optical sheet stacked on the exit surface, and a light shielding member defining an effective area of the exit surface An optical sheet fixing method for a planar illumination device, comprising: a light source disposed opposite to a light incident surface of the light guide plate; and a frame for housing these components. A convex portion projecting toward the inner peripheral surface of the frame is formed at an edge portion of the light guide plate facing the light incident surface, and the convex portion of the frame is opposed to the convex portion. The fixing method which forms the recessed part by which a convex part is arrange | positioned.
(13) In the above item (12), the convex portion of the optical sheet is provided with a widened portion that extends in a surface direction of the optical sheet in a direction toward the inner peripheral surface of the frame, and the convex portion of the frame is provided with the convex portion. The fixing method which provides the widened part which has a complementary relationship with the widened part of a part.
(14) The fixing method according to (12) and (13), wherein two or more convex portions of the optical sheet and concave portions of the frame are provided, and at least one of them is formed in a shape different from the other portions.
(15) The fixing method according to (14), wherein the optical sheet is formed with a notch shape in at least one convex portion having a shape different from that of other portions.
(16) The fixing method according to the above (15), wherein a convex shape corresponding to the notch shape of the convex portion of the optical sheet is formed in the corresponding concave portion of the frame.

(17) In the above items (12) to (16), the position of the edge portion on the light incident surface side of the light guide plate is higher as the optical sheet is provided with a plurality of the optical sheets and the number of stacked layers counted from the emission surface is higher. Is formed so as to be separated from the light incident surface of the light guide plate, and the light shielding member is extended from the light incident surface side of the light guide plate so as to cover the vicinity of each edge portion of the plurality of optical sheets. A fixing method for fixing to each optical sheet.
(18) In the above item (17), a thickness of the light exiting surface of the light guide plate within a predetermined width near the central portion from the light incident surface is set at a central portion of the light guide plate. An inclined surface that is thinner toward the center is formed, a range closer to the center than the inclined surface is set to a constant thickness, and a range of a predetermined width from an edge of the light guide plate on the light incident surface side of the plurality of optical sheets A fixing method in which the light is inclined following the inclined surface formed on the light exit surface of the light guide plate.

(19) In the above item (18), the optical sheet in which the stacking step counted from the emission surface is positioned at the uppermost step among the plurality of optical sheets does not hit the inclined surface of the optical sheet positioned at the lower step. The fixing method which arrange | positions in parallel with the output surface of the part of the fixed thickness of the said light-guide plate.
(20) In the above item (19), among the plurality of optical sheets, the guide of the optical sheet located on the uppermost surface of the optical sheet in which the stacking step counted from the light exit surface is located at the uppermost stage and the optical sheet located immediately below the upper surface is provided. The fixing method which makes the position which concerns on the lamination direction of the said some optical sheet correspond with the upper edge of the edge part by the side of the light-incidence surface of an optical plate correspond to or substantially correspond.

(21) In the above paragraphs (18) to (20), of the plurality of optical sheets, an end of the optical sheet on which the laminated stage counted from the exit surface is positioned at the lowest stage is on the light incident surface side of the light guide plate With respect to the upper edge of the edge portion, the position of the optical sheet located immediately above the upper edge of the edge portion on the light incident surface side of the light guide plate in the stacking direction of the plurality of optical sheets is downward. Fixing method to place.
(22) In the above items (17) to (21), the plurality of optical sheets are stacked on the first sheet with the first sheet having the first stacked layer counted from the light exit surface of the light guide plate. A fixing method including two sheets and a third sheet laminated on the second sheet.
And according to the fixing method of the optical sheet as described in said (12) to (22) term, respectively, there exists an effect | action corresponding to the planar illuminating device of said (1) to (11) term.

Since the present invention is configured as described above, it further promotes further narrowing of the frame lighting device, in particular, narrowing of the frame extending at least in a direction orthogonal to the light incident surface of the light guide plate, and is also performed by the surface lighting. It is possible to reliably position the optical sheet in the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS The planar illuminating device which concerns on the 1st Embodiment of this invention is shown, (a) is a top view, (b) is the A section enlarged view of (a), (c) is the principal of (b). FIG. It is sectional drawing which shows the planar illuminating device which concerns on the 2nd Embodiment of this invention. It is a principal part perspective view of the planar illuminating device shown by FIG. 2, (a) shows the state before sticking a light shielding sheet to an optical sheet, (b) shows the state after sticking. It is a principal part perspective view which shows the example of application to the planar illuminating device which has a sheet-metal frame. It is a perspective view which shows the front and back of an optical sheet, and the upper and lower discrimination means. It is a perspective view which shows the flame | frame and optical sheet | seat of a planar illuminating device, (a) is what used the conventional optical sheet | seat which has a tab as a reference example, (b) is 2nd implementation of this invention. The form of is shown. FIG. 1 shows a liquid crystal display device including a conventional planar illumination device, where (a) is a plan view, (b) is a sectional view taken along line DD in (a), and (c) is a sectional view taken along line EE in (a). FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, about the same part as a prior art, or a part corresponding, the same code | symbol is attached | subjected suitably and detailed description is abbreviate | omitted. Further, the directions of “up” and “down” in the following description mean the vertical direction in the state where the planar lighting device in the present description is placed flat.
FIG. 1 shows a planar illumination device 10 according to a first embodiment of the present invention. Since the entire configuration of the planar illumination device 10 is the same as that of the planar illumination device according to the second embodiment of the present invention described later, also refer to FIG. 2 according to the second embodiment as appropriate. However, it will be described below.

First, the light guide plate 12 in which one of the opposing main surfaces 12a and 12b is a light exit surface, at least one optical sheet 18 stacked on the exit surface 12a, and the effectiveness of the exit surface 12a A light shielding member 20 that defines an area, an LED (which is a point light source) disposed as opposed to the light incident surface 12 c of the light guide plate 12, and a synthetic resin for housing these components And a frame 16 consisting of By the way, the “effective area” of the emission surface 12 a defined by the light shielding member 20 is affected by the reflection of light on the side end surface of the light guide plate 12 and the uniformity of the emitted light is reduced. This is an area excluding the “ineffective area” that inevitably occurs in the vicinity of the edge of the emission surface 12a. In the planar illumination device described in this section, the non-effective area is covered with the light shielding member 20 in a plan view of the emission surface 12a of the light guide plate 12, and the emitted light from the effective area is used to the maximum extent possible. For example, a light shielding sheet is used for the light shielding member 20.
In addition, the part shown by the code | symbol 16b in FIG. 2 is an attachment seat for positioning the reflective sheet 118, and using this double-sided tape 127 (refer FIG.7 (b)) with respect to this attachment seat 16b, A reflective tape 118 is fixed.

The number of optical sheets 18 to be used is appropriately determined as necessary, but in the present embodiment, the number of stacked layers counted from the light exit surface 12a of the light guide plate 12 is the first sheet 181 of the first stage, It includes three optical sheets 18, a second sheet 182 stacked on one sheet 181 and a third sheet 183 stacked on the second sheet 182. As an example, the first sheet 181 is a diffusion sheet, the second sheet 182 is a lower prism sheet, and the third sheet 183 is an upper prism sheet.
Each of the optical sheets 181, 182, and 183 has an edge 18 b (181 b, 182 b, and 183 b) on the side of the light guide plate 12 facing the light incident surface 12 c facing the surface 12 e (see FIG. 2). The protrusions 181bA and 182bA projecting toward the inner peripheral surface of the frame 16 on the end edge portions 181b, 182b, and 183b of the optical sheet 18 in a state of being in contact with the inner peripheral surface of the optical sheet 18 and aligned in a plan view. , 183bA is formed. Since these convex portions are formed in the same position at the same position in plan view, in FIG. 1 showing these plan views, the respective convex portions are indicated by a common symbol 18bA. Further, referring to FIG. 1, the convex portions 18bA projecting toward the inner peripheral surface of the frame 16 are formed at two locations (18bA1, 18bA2). Then, two concave portions 16dA (16dA1, 16dA2) in which the convex portions 18bA1 and 18bA2 are arranged are formed in a portion of the frame 16 facing the convex portion 18bA.

Further, as shown in an enlarged view in FIG. 1C, a widened portion in which at least the distal end portions of the convex portions 18bA1 and 18bA2 of the optical sheet 18 spread in the surface direction of the optical sheet 18 as compared with the base end portion. Have. The concave portions 16dA1 and 16dA2 of the frame 16 also include widened portions having a complementary relationship with the widened portions of the convex portions 18bA1 and 18bA2 of the optical sheet 18. In the example of FIG. 1, the convex portions 18bA1 and 18bA2 of the optical sheet 18 and the concave portions 16dA1 and 16dA2 of the frame 16 are arranged with a space therebetween and have different shapes.
More specifically, as shown in FIG. 1B, a notch shape r is formed in one convex portion 18bA2 of the optical sheet 18. Although not essential, a convex shape p corresponding to the notch shape r may be appropriately formed in the corresponding concave portion 16dA2 of the frame 16.
As shown in the upper part of FIG. 1C, an inevitable gap in terms of dimensional accuracy is secured in plan view between the convex portion 18bA of the optical sheet 18 and the concave portion 16dA of the frame 16. .

Now, according to the embodiment of the present invention configured as described above, the following operational effects can be obtained.
First, the planar illumination device 10 according to the first exemplary embodiment of the present invention has an inner periphery of a frame on an edge 18b of the optical sheet 18 on the side of the surface 12e facing the light incident surface 12c of the light guide plate 12. A convex portion 18bA protruding toward the surface is formed. Then, the convex portion 18bA is disposed in the concave portion so as to engage with the concave portion 16dA formed in the portion of the frame 16 facing the convex portion 18bA, thereby positioning the optical sheet 18 with respect to the frame 16. Is to be made. According to this configuration, as shown in FIG. 1, the concave portion 18bA is formed in the portion of the frame 16 that is related to the edge portion on the side of the facing surface 12e of the light guide plate 12 facing the light incident surface 12c. 18bA and the recess 16dA exert a positioning function between the optical sheet 18 and the frame 16, and in particular, a portion extending in a direction orthogonal to the light incident surface of the light guide plate of the frame 16 (see the recess 124c in FIG. 6A). ), It is not necessary to form a recess, and it is possible to promote narrowing of the frame at this portion.

  Further, the widened portion of the convex portion 18bA1 of the optical sheet 18 whose tip end portion extends in the surface direction of the optical sheet 18 as compared with the base end portion, and the widened portion of the convex portion 18bA of the concave portion 16dA1 of the frame 16 are complementary. As shown in the lower part of FIG. 1C, the so-called undercut structure (the lower part of FIG. 1C) restricts the relative movement in the direction Y in which the optical sheet 18 is separated from the frame 16, as shown in the lower part of FIG. The portion surrounded by an ellipse U). Even if the position is displaced by an inevitable gap in terms of dimensional accuracy, which is ensured between the convex portion 18bA of the optical sheet 18 and the concave portion 16dA of the frame 16, due to this undercut structure, more than that. A large positional deviation is restricted, and the positioning function between the frame 16 and the optical sheet 18 is enhanced. In the example shown in the figure, the widened portion forms a trapezoidal shape to form an undercut structure, but other shapes having similar functions may be employed.

Further, the convex portion 18bA of the optical sheet 18 and the concave portion 16dA of the frame 16 are provided at two or more locations, and the two convex portions 18bA of the optical sheet 18 and the two concave portions 16dA of the frame 16 are located at positions separated from each other. By being arranged, the positioning function of the frame 16 and the optical sheet 18 is exhibited at each location. A necessary and sufficient positioning effect can be obtained without forming a recess in a portion extending in a direction perpendicular to the light incident surface of the light guide plate of the frame 16 (see the recess 124c in FIG. 6A). . In the illustrated example, both the convex portions 18bA1 and 18bA2 of the optical sheet 18 and the concave portions 16dA1 and 16dA2 of the frame 16 are provided in two places, but a larger number may be provided as appropriate.

In addition, since the convex portion 18bA of the optical sheet 18 and the concave portion 16dA of the frame 16 have different shapes, the optical sheet 18 also functions as a front / back / upper / lower discriminating means. In addition, the front / back and top / bottom of the optical sheet 18 can also be discriminated by the notch shape r formed in one convex portion 18bA2 of the optical sheet 18. With this discrimination function, the convex portions 181bA, 182bA, 183bA of the plurality of optical sheets 18 can be formed in the same shape at the same position in plan view, and the concave portions 16dA1, 16dA2 of the frame 16 corresponding thereto. Can be made common to the convex portions 181bA, 182bA, 183bA of each optical sheet 18.
Further, as illustrated in FIG. 1B, if the convex shape p corresponding to the notched shape r of the convex portion 18bA2 of the optical sheet 18 is formed in the concave portion 16dA2 of the corresponding frame 16, these notched shapes are formed. The positioning function between the frame 16 and the optical sheet 18 can be enhanced also by the engagement of r and the convex shape p.

2 to 4 show a planar illumination device according to the second embodiment of the present invention. Here, the same or corresponding parts as those of the first embodiment of the present invention are denoted by the same reference numerals and detailed description thereof is omitted. The planar illumination device 10 according to the second embodiment of the present invention also has the configuration of the planar illumination device 10 according to the first embodiment shown in FIG. It has various features.
In the present embodiment, the optical sheets 181, 182, and 183 are configured so that end edges 181 b, 182 b, and 183 b of the light guide plate 12 on the side facing the light incident surface 12 c (see FIG. 2) are 181 b, 182 b, and 183 b of the frame 16. The optical sheet with the upper stage of the laminated stage counted from the exit surface 12a of the light guide plate 12 in contact with the inner peripheral surface and aligned in plan view, the edge 181a on the light incident surface 12c side of the light guide plate 12 , 182a, 183a are formed so as to be separated from the light incident surface 12c of the light guide plate 12.

Then, the light shielding member 20 extends from the light incident surface 12c side of the light guide plate 12 to the vicinity of the edge portions 181a, 182a, 183a of the optical sheets 181, 182, 183 on the light incident surface 12c side of the light guide plate 12. It extends to cover. The light shielding member 20 is, for example, a double-sided tape 130 (see FIG. 3) with respect to the vicinity of the edge portions 181a, 182a, 183a of the optical sheets 181, 182, 183 on the light incident surface 12c side of the light guide plate 12. ) Or bonding.

In addition, in the range of a predetermined width of the light exit surface 12a of the light guide plate 12 closer to the center portion from the light incident surface 12c, an inclined surface 12d that reduces the thickness between a pair of opposing main surfaces toward the center portion of the light guide plate. The range closer to the center than the inclined surface 12d has a constant thickness.
Of the optical sheets 181, 182, and 183, the first sheet 181 and the second sheet 182 have a predetermined width range from the edge portions 181 a and 182 a on the light incident surface 12 c side of the light guide plate 12. It is inclined following the inclined surface 12d formed on the emission surface 12a.

In the example shown in FIG. 2, the wiring substrate 132 of the light source 14 is inclined along the inclined surface 12 d of the light guide plate 12 and is fixed to the inclined surface 12 d with a double-sided tape 130. Then, by laminating the first sheet 181 on the wiring board 132, a range of a predetermined width from the end edge 181a on the light incident surface 12c side of the light guide plate 12 follows the inclined surface 12d of the light guide plate 12. Inclined. In addition, the second sheet 182 is laminated on an inclined portion having a predetermined width from the edge 181a on the light incident surface 12c side of the light guide plate 12 of the first sheet 181, so that the light incident surface of the light guide plate 12 is laminated. A range of a predetermined width from the end edge 182a on the 12c side is also inclined following the inclined surface 12d of the light guide plate 12. The “predetermined width range” is determined by the positional relationship between the inclined surface 12 d of the light guide plate 12 and the edge portions 181 a and 182 a of the sheets 181 and 182.
On the other hand, the third sheet 183 in which the stacking stage counted from the light exit surface 12a of the light guide plate 12 is positioned at the uppermost stage does not reach the inclined surface of the second sheet 182 positioned immediately below the third sheet 183, and the light guide plate 12 is fixed. Are arranged in parallel with the exit surface 12a of the thickness portion.

Also, as shown in FIG. 2, among the optical sheets 181, 182, and 183, the upper surface 183c of the third sheet 183 in which the stacking stage counted from the exit surface 12a of the light guide plate 12 is positioned at the uppermost stage, and immediately there The position (vertical direction position) in the stacking direction of the optical sheet 18 with the upper edge 182e of the edge 182a on the light incident surface 12c side of the light guide plate 12 of the second sheet 182 positioned in the lower stage is not coincident. It is almost coincident.
Further, among the optical sheets 181, 182, and 183, the edge portion on the light incident surface side 12 c of the light guide plate 12 of the first sheet 181 in which the stacking level counted from the light exit surface 12 a of the light guide plate 12 is located at the lowest level. The position of the upper edge 182e of the edge 182a on the light incident surface 12c side of the light guide plate 12 of the second sheet 182 positioned immediately above the upper edge 181e of 181a in the stacking direction of the optical sheet 18 ( (Position in the vertical direction) is located below.

  FIG. 4 shows an example in which the frame 16 made of the synthetic resin shown in FIG. 2 is replaced with a sheet metal frame 22 as an application example of the present invention. Also in this application example, the light guide plate 12, the optical sheets 181, 182, 183, and the light shielding member 20 have the same configuration as the example of FIGS. 2 and 3, and an appropriate technique (construction method) is applied to the sheet metal frame 22. ) To provide a recess (not shown) that exhibits the same function as the recess 16dA of the resin frame 16 shown in FIG. Since the frame is the sheet metal frame 16, the frame itself has greater strength than the resin frame. Although not shown in FIG. 4, the metal plate 22 is provided with protrusions for positioning the respective components in the side surface direction orthogonal to the light incident surface 12 c of the light guide plate 12 as necessary. Also good.

  Further, as illustrated in FIG. 5, as illustrated in FIG. 5, for example, the edge portion 181 a on the light incident surface side of the light guide plate of the first and second sheets can be used as a front / back / upper / lower determination unit of each optical sheet. , 182a may be provided with C surface portions 181c and 182c, and a tab 183d may be provided at an asymmetrical position in plan view on the edge portion 183a of the third sheet 183 on the light incident surface side of the light guide plate.

Now, according to the second embodiment of the present invention configured as described above, in addition to the functions and effects described in the first embodiment, the following functions and effects can be obtained.
That is, as a function and effect peculiar to the second embodiment of the present invention, the positions of the end edges 181a, 182a, 183a of the light guide plate 12 on the light incident surface 12c side of the plurality of optical sheets 181, 182, 183 are as follows. In addition, the upper optical sheet in the number of stacked layers counted from the light exit surface 12a of the light guide plate 12 is formed so as to be separated from the light incident surface 12c of the light guide plate 12, so that the light exit surface 12a of the light guide plate 12 is viewed in plan view. In the aspect, the edge portions 181a, 182a, 183a of the optical sheets 181, 182, 183 on the light incident surface 12c side of the light guide plate 12 are exposed without being covered by the optical sheets positioned on the upper stage. Become. The light shielding member 20 is attached to the exposed edge portions 181a, 182a, 183a of the optical sheets 181, 182, 183 from the light incident surface 12c side of the light guide plate 12, and the edge portions 181a of the plurality of optical sheets 18 are provided. By extending so as to cover the vicinity of 182a and 183a, the vicinity of the edge portions 181a, 182a and 183a of all the optical sheets 181, 182 and 183 is fixed by the light shielding member 20.

  In addition, a range of a predetermined width from the end edge portions 181 a and 182 a on the light incident surface 12 c side of the light guide plate 12 of the plurality of optical sheets 181 and 182 follows the inclined surface 12 d formed on the light exit surface 12 a of the light guide plate 12. The light shielding member 20 extending from the light incident surface 12c side of the light guide plate 12 so as to cover the vicinity of the edge portions 181a, 182a, 183a of the plurality of optical sheets 181, 182, 183 The optical sheets 181 and 182 are fixed along the inclined surfaces. This prevents the light shielding member 20 extending from the light incident surface 12c side of the light guide plate 12 from forming a steep bent portion and sufficiently secures the light shielding member 20 with respect to the optical sheets 181, 182, and 183. It becomes possible to do.

  In addition, the optical sheet 183 having the uppermost laminated layer counted from the light exit surface 12a of the light guide plate 12 is arranged in parallel with the light exit surface 12a of the constant thickness portion of the light guide plate 12, so that the light guide plate The vicinity of the front end portion 20a of the light shielding member 20 extending so as to cover the vicinity of the end edge portions 181a, 182a, 183a of the plurality of optical sheets 181, 182, 183 from the 12 light incident surface 12 c side is also located at the uppermost stage. On the optical sheet 183, it will be arrange | positioned in parallel with the output surface 12a of the light-guide plate 12. FIG. Then, an object to be illuminated such as an LCD polarizing film (see LCD 110, pair of glass substrates 112 and polarizing plate 114 in FIG. 7) is mounted on the surface of the light shielding member 20 parallel to the exit surface 12a of the light guide plate 12. This makes it possible to stabilize the illuminated object.

  In the second embodiment of the present invention, the upper surface 183c of the third sheet 183 positioned at the uppermost stage and the end of the second sheet 182 positioned immediately below the upper side of the light guide plate 12 on the light incident surface 12c side. The position of the optical sheet 18 in the stacking direction (vertical direction) with the upper edge 182e of the edge 182a is coincident or substantially coincident. As a result, the position in the vicinity of the distal end portion 20 a of the light shielding member 20 in the stacking direction of the optical sheet 18 is arranged in parallel with the emission surface 12 a of the light guide plate 12. That is, the vicinity of the front end portion 20a of the light shielding member 20 is not only the upper surface 183b of the third sheet 183 positioned at the uppermost stage, but also by the upper edge 182e of the end edge part 182a of the second sheet 182 positioned immediately below it. The positions of the plurality of optical sheets 18 in the stacking direction are supported in a manner that matches or substantially matches, so that the vicinity of the tip 20a of the light shielding member 20 extends over a wider area and the light exit surface 12a of the light guide plate 12. In parallel, it will be stably supported.

  In addition, the first sheet 181 having the lowest number of stacked layers counted from the light exit surface 12a of the light guide plate 12 is immediately above the upper edge 181e of the end edge 181a on the light incident surface 12c side of the light guide plate 12. The position of the upper edge 182e of the edge 182a on the light incident surface 12c side of the light guide plate 12 of the second sheet 182 positioned in the position related to the stacking direction (vertical direction) of the plurality of optical sheets 18 is positioned below. ing. As a result, the light shielding member 20 extending from the light incident surface 12c side of the light guide plate 12 so as to cover the vicinity of the edge portions 181a, 182a, 183a of the plurality of optical sheets 18 of the first sheet 181 located at the lowermost stage. The inclined surface is constructed following the inclined surface. Then, the inclined surface of the light shielding member 20 is maintained from the lowermost optical sheet 181 to the position where the light shielding member 20 rides over the optical sheet 182 located immediately above the optical sheet 181 (the light shielding member 20 in FIG. 2). Reference numeral 182e is a peripheral portion). This also prevents a steep bent portion from being formed on the light shielding member 20 and ensures sufficient fixing strength of the light shielding member 20 with respect to each optical sheet 18.

Due to the above-described effects, according to the second embodiment of the present invention, as shown in FIG. 6B, the optical sheet 18 is provided with the tabs (the tab 120a and the tab 120a in FIG. 6A). It is possible to reliably position the optical sheet 18 in the planar illumination device 10 without forming the recess 124c of the frame 124 for receiving. In particular, in the second embodiment of the present invention, since different positioning mechanisms are provided at the edge portions of the optical sheet 18 that face each other, the optical sheet 18 can be positioned more reliably. Become. Then, it is possible to reduce the thickness of the frame 16 in the direction of the arrow B due to the provision of the tabs on the optical sheet 18 and to promote further narrowing of the frame lighting device 10. In addition, it is possible to suppress the occurrence of uneven brightness in the planar lighting device 10 due to the provision of the tabs on the optical sheet 18.
In the second embodiment of the present invention, the plurality of optical sheets stacked on the light exit surface of the light guide plate includes the first sheet 181, the second sheet 182, and the third sheet 183. However, it will be understood that the same effect can be obtained even if the number of optical sheets 18 is increased or decreased.

10 plane illumination device, 12 light guide plate, 12a: exit surface, 12b: main surface facing the exit surface, 12c: light incident surface, 12d: inclined surface, 12e: facing surface, 14: light source, 16: frame, 18 : Optical sheet, 181: first sheet, 182: second sheet, 183: third sheet, 181a, 182a, 183a: edge part on the light incident surface side of the light guide plate, 183c: upper surface of the third sheet, 181e, 182e: upper edge of edge, 20: light shielding member, 22: sheet metal frame

Claims (10)

A light guide plate having one of a pair of opposing main surfaces as a light exit surface, at least one optical sheet laminated on the exit surface, a light shielding member for defining an effective area of the exit surface, and the light guide A planar illumination device including a light source disposed opposite to a light incident surface of a light plate, and a frame for housing these components,
In the optical sheet, a convex portion that protrudes toward the inner peripheral surface of the frame is formed at an edge portion of the light guide plate facing the light incident surface, and a portion facing the convex portion of the frame. Further, a concave portion in which the convex portion is disposed is formed. The convex portion of the optical sheet has a widened portion that extends at least in the surface direction of the optical sheet as compared to the base end portion, and is complementary to the widened portion of the convex portion in the concave portion of the frame. The planar illumination device according to claim 1, further comprising a widened portion having the following relationship. The convex portion of the optical sheet and the concave portion of the frame are provided in two or more places, and at least one of them has a shape different from other places. Planar lighting device. The planar illumination device according to claim 3, wherein a cutout shape is formed in at least one convex portion having a shape different from other portions of the optical sheet. The optical sheet is provided with a plurality of optical sheets, and the position of the edge portion on the light incident surface side of the light guide plate is separated from the light incident surface of the light guide plate as the optical sheet is stacked in the upper stage counted from the emission surface. The light shielding member is formed and extends from the light incident surface side of the light guide plate so as to cover the vicinity of each edge portion of the plurality of optical sheets, and is fixed to each optical sheet. The planar illumination device according to any one of claims 1 to 4. An inclined surface is formed in a range of a predetermined width near the center portion from the light incident surface of the light exit surface of the light guide plate so that the thickness between the opposed pair of main surfaces decreases toward the center portion of the light guide plate. The range closer to the center than the inclined surface has a constant thickness,
A range of a predetermined width from an end edge portion on the light incident surface side of the light guide plate of the plurality of optical sheets is inclined following an inclined surface formed on an output surface of the light guide plate. The planar illumination device according to claim 5. Among the plurality of optical sheets, the optical sheet in which the stacking stage counted from the light exit surface is positioned at the uppermost stage does not hit the inclined surface of the optical sheet positioned at the lower stage, and is a portion having a certain thickness of the light guide plate The planar illumination device according to claim 6, wherein the planar illumination device is arranged in parallel with the light exit surface. Of the plurality of optical sheets, the upper surface of the optical sheet in which the stacking step counted from the light exit surface is located at the uppermost stage, and the edge of the optical sheet located immediately below the optical sheet on the light incident surface side of the light guide plate The planar illumination device according to claim 7, wherein positions of the plurality of optical sheets in the stacking direction coincide with or substantially coincide with an upper edge of the sheet. Among the plurality of optical sheets, the optical sheet in which the stacking stage counted from the exit surface is located at the lowest stage is located immediately above the upper edge of the edge on the light incident surface side of the light guide plate. The position of the upper edge of the edge of the light guide plate on the light incident surface side of the optical sheet in the stacking direction of the plurality of optical sheets is positioned below. The surface illumination device according to any one of the above. The plurality of optical sheets are stacked on the first sheet, the first sheet having the first stacking stage counted from the exit surface of the light guide plate, the second sheet stacked on the first sheet, and the second sheet. The planar illumination device according to any one of claims 5 to 9, further comprising a third sheet.

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