JP2010086755A - Surface light-emitting lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface light-emitting lighting device that prevents forming of light-reflecting sheet wrinkles without fail, leading to stable irradiation of planar outgoing light with uniform luminance distribution. <P>SOLUTION: A light guide plate 1 is held on a frame 2 in a way in which first protrusions 16a, 16b, formed in protrusion on an opposite light incidence side on both side end faces of the light guide plate are inserted into first engagement grooves 23a, 23b which are formed on corresponding inner side locations of the frame 2 short-hand side panels 211, 213, opened towards a light outgoing side (front side); and second protrusions 17a, 17b, protruded toward a light-incidence side are inserted into second engagement grooves 24a, 24b which are likewise formed on corresponding inner-side locations of the frame 2 and opened towards the opposite light outgoing side (rear side). Thereby, a wedge-shaped space S, gradually increasing its height towards an opposite light incidence side, is secured between the rear face 13 of the light guide plate and a light reflection sheet 5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a side light type surface emitting illumination device.

  In recent years, liquid crystal display panels have been used as displays for mobile devices such as mobile phones and PDAs (Personal Digital Assistance) because they are advantageous for thinning applied devices. As a backlight of this liquid crystal display panel, a sidelight surface emitting irradiation panel that is advantageous for thinning is suitably used.

  As shown in Patent Document 1, a side-light type surface-emitting irradiation panel usually has a light source opposed to one end surface of a rectangular light guide plate and a main surface (front surface) that emits light from the light guide plate. Is formed by forming a fine concavo-convex pattern on the opposite main surface (back surface) and arranging a light reflecting sheet.

  According to this side light type surface emitting irradiation panel, the light emitted from the light source enters the light guide plate from the opposite end surface, and the back surface unevenness when the incident light propagates through the light guide plate repeatedly by internal reflection. Light that is internally reflected on the surface side by the pattern is emitted as irradiation light.

Here, the propagating light incident on the concavo-convex pattern on the back side also includes light that exits to the outside without being internally reflected on the front side, but such externally emitted light is also reflected by the light reflecting sheet and again in the light guide plate. Is emitted to the front side as irradiated light.
JP 2008-175926 A

  The light reflecting sheet is usually placed on the back surface of the light guide plate. In this case, the thickness of the light reflecting sheet is as thin as about 0.07 mm. There is a problem that wrinkles are likely to occur due to partial contact with the back surface of the optical plate, and this wrinkle causes variations in the luminance distribution of the emitted light.

  An object of the present invention is to provide a surface-emitting illuminating device that can reliably prevent the occurrence of wrinkles on a light reflecting sheet and can stably obtain planar illumination light having a uniform luminance distribution.

  The invention of the surface-emitting illuminating device according to claim 1 of the present invention includes a light source, a light guide plate that makes light emitted from the light source incident from an end surface, and emits the incident light in a planar shape from one main surface, A light reflecting sheet disposed facing the other main surface of the light guide plate, and a light incident side edge of the light guide plate opposite to the light incident side of the other main surface is the light reflecting sheet. And a frame body that is held in a state of being opposed to each other by providing a space.

  According to a second aspect of the present invention, in the surface-emitting illumination device according to the first aspect, the light guide plate has a rectangular shape, and the light incident side and the anti-light incident side at the pair of side end surfaces excluding the light incident side end surface and the opposite end surface. 1st and 2nd convex part is provided, respectively, The said frame has a side plate which faces each side end surface of the said light-guide plate, The said 1st convex part is formed in the inner surface of each side plate of the said frame A first engagement groove opened on the light emission side is formed at a position corresponding to, and a second engagement groove opened on the counter light emission side is formed at a position corresponding to the second protrusion. It is characterized by.

  According to a third aspect of the present invention, in the surface-emitting illumination device according to the first or second aspect, the surface emitting illumination device further includes an outer case that houses the frame body on which the light guide plate is engaged and held and the light reflecting sheet. It is characterized by this.

  According to the present invention, it is possible to provide a surface-emitting illuminating device that can reliably prevent the occurrence of wrinkles on the light reflecting sheet and can stably obtain planar irradiation light having a uniform luminance distribution.

  FIG. 1A is a plan view showing a surface emitting illumination device as one embodiment of the present invention, FIG. 1B is a sectional view taken along line BB, and FIG. 1C is a sectional view taken along line CC. . 2A and 2B are a sectional view taken along line IIa-IIa and a sectional view taken along line IIb-IIb in FIG. 1A, respectively.

  In the surface-emitting illuminating device of this embodiment, a light guide plate 1 having a generally rectangular flat plate shape is supported at a predetermined position by a frame 2, and a light source is provided on one long side end surface (hereinafter referred to as a light incident end surface) 11 of the light guide plate. A plurality of LEDs (Light-Emitting Diodes) 3 are arranged, and an optical sheet laminate 4 is installed on one main surface (hereinafter referred to as the front surface) 12 that emits light from the light guide plate 1, and the main surface on the opposite side. A light reflecting sheet 5 is provided on the side of the surface (hereinafter referred to as the rear surface) 13 to form a surface emitting irradiation panel, and this surface emitting irradiation panel is housed in an exterior case 6.

  In this surface emitting illumination device, the light emitted from the LED 3 enters the light guide plate 1 from the facing light incident end surface 11, and the incident light propagates through the light guide plate 1 to the front surface 12 by the rear surface 13. The light is reflected from the inner surface and emitted from the front surface 12 in a planar shape. The light emitted in a planar shape from the front surface 12 passes through the optical sheet laminate 4 to become a planar irradiation light having a substantially uniform luminance distribution and a sufficiently high luminance in the front direction.

  The light guide plate 1 is molded into a substantially transparent rectangular plate using a resin material such as polycarbonate. On the rear surface 13 of the light guide plate 1, a fine concavo-convex pattern (not shown) for internally reflecting light incident on the light guide plate 71 is formed. The concavo-convex pattern of the present embodiment is a satin pattern in which a large number of fine protrusions are erected, and the erection density of the protrusions is set to increase as the distance from the end face on the LED installation side increases.

  3A and 3B are a plan view and a side view showing the light guide plate 1 alone, respectively. As shown in the figure, first and second convex portions 16 and 17 are provided on both side end surfaces 14 and 15 of the light guide plate 1, respectively. The pair of first protrusions 16a and 16b provided at positions far from the light incident end face 11 (on the opposite light incident side) project each ear having a length L1 and a width W1 from the front surface 12 over a predetermined thickness t. It is formed in a different shape. On the other hand, the pair of second convex portions 17a and 17b provided at positions close to the light incident end face 11 are provided so as to protrude from the rear face 13 by a predetermined height h. Each of the second protrusions 17a and 17b has a protrusion width W2 that is larger than the protrusion width W1 of the first protrusion 16, and the length L2 of one second protrusion 17a is the other second protrusion 17b. Longer than that.

  On the other hand, the frame 2 holding the light guide plate 1 formed as described above corresponds to the first convex portions 16a and 16b and the second convex portions 17a and 17b as shown in FIG. Thus, the first engagement grooves 23a and 23b and the second engagement grooves 24a and 24b are provided. The frame 2 is made of a resin material and is integrally formed into a shape shown in FIGS. 4A and 4B which are a plan view showing a single body and a cross-sectional view taken along line BB.

  That is, the frame 2 includes three side plates 211, 213, and 214 except for one of the long side plates 212 among the four side plates 211 to 214 surrounding a rectangular parallelepiped space substantially corresponding to the outer shape of the light guide plate 1. Shelves 22a, 22b, and 22c are respectively provided on each inner surface. The shelves 22a to 22c are projected from a position lower than the upper surface (light emission side) of each side plate 211, 213, 214 by a predetermined depth d1. The protruding widths of the shelf portions 22a to 22c are set such that the protruding width w1 of the short shelf portions 22a and 22b is smaller than the protruding width w2 of the long shelf portion 22c.

  Then, on the opposite side (reverse light incident side) of the pair of short shelves 22a and 22b to the light source arrangement side, the first convex portions 16a and 16b of the light guide plate 1 are made to correspond to the first convex portions 16a and 16b. 1 engaging groove 23a, 23b is formed, respectively. The first engagement grooves 23a and 23b have a depth d2 substantially equal to the thickness t of the first protrusions 16a and 16b, and a width W3 and a length L3 that are the length L1 and the width of the first protrusions 16a and 16b. The dimension is set slightly larger than W1. Each width W2 of the first engagement grooves 23a and 23b is set to a dimension equal to the protruding width w1 of the short shelf portions 22a and 22b.

  On the other hand, the second engagement grooves 24a opened on the frame lower surface side (rear surface side) corresponding to the second convex portions 17a and 17b at positions close to the light source arrangement side of the shelf portions 22a and 22b (light incident side), 24b is formed. The second engagement grooves 24a and 24b can accommodate the corresponding second convex portions 17a and 17b at positions where the heights of the upper bottom surfaces from the lower surface of the frame are H, with a slight floating width. It is formed in size.

  Concave portions 25 for accommodating the corresponding short side edges of the light reflecting sheet 5 are formed on the lower surfaces of the short side plates 211 and 213, respectively.

  Returning to FIG. 1, in this embodiment, three LEDs 3 are installed as light sources with their light exit surfaces facing the light incident end surface 11 of the light guide plate 1 and directly mounted on the FPC 31 by the COF (Chip On Film) method. Has been. The FPC (hereinafter referred to as “light source FPC”) 31 is provided between the light incident side end portion of the light guide plate front surface 12 and the frame shelf portion 22c.

  On the front surface 12 of the light guide plate 1, an optical sheet laminate 4 as a light control member is installed. The optical sheet laminate 4 is formed by sequentially laminating a diffusion sheet 41, a first prism sheet 42, and a second prism sheet 43 on the light emitting surface 12 of the light guide plate 1. Each of the first and second prism sheets 42 and 43 is formed by extending protrusions (not shown) having a plurality of cross-sections forming a right triangle extending in parallel at a fine pitch, and the protrusions are orthogonal to each other. It is placed in a superimposed manner.

  In addition, the light reflecting sheet 5 is disposed facing the rear surface 13 of the light guide plate 1. The light reflecting sheet 5 is a multilayer film that does not contain a metal component made of polyester, has a reflectance as high as 90% or more with respect to all wavelengths in the visible light range, and a thickness as thin as about 65 μm.

  And the surface emitting irradiation panel which consists of the light-guide plate 1 mentioned above and the flame | frame 2, LED3, the optical sheet laminated body 4, and the light reflection sheet 5 holding this is accommodated in the exterior case 6 produced by sheet metal processing, The surface-emitting illumination device of the embodiment is obtained. Here, the light reflecting sheet 5 placed on the bottom surface 61 of the outer case is provided on each bottom surface of the short side plates 211 and 213 of the frame 2 as shown in FIGS. 2 (a) and 2 (b). The short side edge corresponding to the recessed portion 25 is accommodated and the arrangement thereof is restricted.

  In the surface emitting illumination device thus obtained, as shown in FIG. 2A, the first protrusions 16 a and 16 b provided on the light incident side of the light guide plate 1 correspond to the frame 2. The first engaging grooves 23a and 23b are engaged and inserted. Here, since the first engagement grooves 23a and 23b are grooves opened upward (front side), the first protrusions 16a and 16b can be simply inserted into the engagement grooves 22a and 22b from the opened front side. The inserted first convex portions 16a and 16b are engaged with the bottom surfaces of the respective engaging grooves 22a and 22b, and the dropping thereof is restricted. In this state, a gap c <b> 1 is ensured between the anti-light incident side portion of the rear surface 13 of the light guide plate and the light reflecting sheet 5 placed on the bottom surface 61 of the exterior case 6. The size of the gap c1 is determined by the thickness t of the first protrusions 16a and 16b, the depth d1 of the shelves 22a and 22b, and the depth d2 of the first engagement grooves 23a and 23b. The

  On the other hand, the second convex portions 17a and 17b provided on the light incident side are inserted into the corresponding second engaging grooves 24a and 24b on the frame 2 side, as shown in FIG. Since the second engagement grooves 24a and 24b are grooves opened downward (rear side), the inserted second protrusions 17a and 17b are only accommodated in the second engagement grooves 24a and 24b. The fall is not regulated. Therefore, the light incident end face 11 of the light guide plate 1 and the edge portion of the rear face 13 are in pressure contact with the light reflecting sheet 5.

  As a result, as shown in FIG. 1 (b), the contact position between the rear surface side edge of the light guide plate light incident end surface 11 and the light reflection sheet 5 between the rear surface 13 of the light guide plate 1 and the light reflection sheet 5. Therefore, a minute space S having a wedge-shaped cross section that gradually spreads from the light incident side toward the reflected light side is secured.

  As a result, the rate at which light emitted to the outside from the rear surface 13 of the light guide plate 1 is reflected and reentered into the light guide plate 1 is higher on the light incident side and gradually lowers toward the anti-light incident side. As a result, the luminance distribution of the planar irradiation light emitted from the front surface 12 is highly uniformed by a synergistic effect with the inner surface reflection action by the uneven pattern provided on the rear surface 13 of the light guide plate.

  Furthermore, the light reflecting sheet 5 is housed between the recess 25 provided on the lower surface (rear side) of the side plate of the frame 2 and the outer case bottom surface 61 so that the movement of the light reflecting sheet 5 is restricted. Since only the light incident side edge is in line contact pressure contact, the generation of wrinkles due to thermal expansion or the like due to the temperature rise of the light reflecting sheet 5 is effectively prevented. Furthermore, since the light reflecting sheet 5 is pressed by the light incident side edge of the rear surface 13 of the light guide plate, the positional deviation of the light reflecting sheet 5 due to vibration or the like is more reliably prevented.

  In addition, the optical sheet laminated body 4 is arrange | positioned on the light-guide plate front surface 12 in the state in which the both-sides edge part was supported by the shelf parts 22a and 22b of the flame | frame 2. As shown in FIG.

  As described above, in the surface emitting irradiation panel module according to this embodiment, the light guide plate 1 is gradually separated toward the light incident side with the light incident side edge of the rear surface 13 in contact with the light reflecting sheet 5. Therefore, even if the light reflecting sheet 5 is thermally expanded due to an increase in environmental temperature, no wrinkle is generated, and the light reflecting sheet 5 is not displaced due to vibration or the like. As a result, it is possible to stably emit planar light having a highly uniform luminance distribution due to a synergistic effect with the internal reflection effect of the uneven pattern provided on the rear surface 13 of the light guide plate.

  The present invention is not limited to the above-described embodiment, and may be configured as shown in FIGS. 5 (a) to 5 (c), for example. 5A to 5C, the same components as those in the above embodiment are denoted by the same reference numerals, the corresponding components are denoted by the corresponding reference numerals, and the description thereof is omitted.

  As is clear from FIGS. 5A to 5C, in the present embodiment, the first convex portions 86a and 86b and the second convex portions 87a and 87b of the light guide plate 8 are both in the same shape on the light guide plate front surface 82 side. The first engaging grooves 93a and 93b and the second engaging grooves 94a and 94b on the frame 9 side that are formed in the same shape and engaged with each other may be formed as grooves having the same shape and opened on the light emitting side. Thus, a minute space S having a constant height is secured between the light reflecting sheet 5 and the rear surface 83 of the light guide plate 8, and wrinkles of the light reflecting sheet 5 are effectively prevented. In this embodiment, the fine protrusions constituting the concavo-convex pattern are erected so that the luminance distribution of the planar emitted light is made uniform only by the internal reflection effect of the fine concavo-convex pattern provided on the rear surface 83 of the light guide plate 8. The density distribution is optimized.

(a) is the top view which showed the surface emitting illuminating device as one Embodiment of this invention, (b) is the BB sectional drawing, (c) is the CC sectional view. (a) is the IIa-IIa sectional view taken on the line in Fig.1 (a), (b) is the IIb-IIb sectional view taken on the line in Fig.1 (a). (a) is the top view which showed the light-guide plate single-piece | unit in the said surface emitting illumination apparatus, (b) is the side view. (a) is the top view which showed the flame | frame single_piece | unit in the said surface emitting illuminating device, (b) is the BB sectional drawing. (a) is the top view which showed the surface emitting illumination device as other embodiment of this invention, (b) is the BB sectional drawing, (c) is CC sectional drawing.

Explanation of symbols

1 and 8 Light guide plate 11 Light incident end surface 12 Front surface (light exit surface)
13 Rear surface (Reverse light exit surface)
14, 15 side end faces 16a, 16b,
86a, 86b first convex portions 17a, 17b,
87a, 87b 2nd convex part 2, 9 Frame 211-214 Side plate 22a, 22b Shelf part 23a, 23b
93a, 93b First engagement grooves 24a, 24b
94a, 94b Second engagement groove 25 Recess 3 LED
4 Optical sheet laminate 5 Light reflecting sheet

Claims (3)

A light source;
A light guide plate that makes light emitted from the light source incident from an end face and emits the incident light in a planar shape from one main surface;
A light reflecting sheet disposed facing the other main surface of the light guide plate;
A frame that holds the light guide plate in a state in which at least a light incident side edge on the opposite side of the light incident side of the other main surface is disposed opposite to the light reflecting sheet; The
A surface-emitting illuminating device comprising: The light guide plate has a rectangular shape, and first and second convex portions are provided on the light incident side and the anti-light incident side of the pair of side end surfaces excluding the light incident side end surface and the opposite end surface thereof, respectively.
The frame has a side plate facing each side end surface of the light guide plate, and a first surface opened on a light emitting side at a position corresponding to the first convex portion on an inner surface of each side plate of the frame. 2. The surface emitting illumination device according to claim 1, wherein the engagement groove is formed with a second engagement groove that is open on a light-emitting side at a position corresponding to the second convex portion. .   3. The surface-emitting illumination device according to claim 1, further comprising an exterior case that houses the frame body and the light reflection sheet on which the light guide plate is engaged and held. 4.

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