JP2019029081A - Planar lighting device - Google Patents

Abstract

To reduce rattle noise caused by a collision between a frame and an optical sheet.SOLUTION: A planar lighting device of an embodiment includes a light guide plate, a frame, and an optical sheet. The light guide plate emits light entering from a side surface from an emission surface. The frame encloses a peripheral edge part of the light guide plate. The optical sheet is disposed at the emission surface side of the light guide plate so as to be enclosed by the frame and has an elastically deformable spring structure at the peripheral edge part.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a planar lighting device.

  Conventionally, a planar illumination device configured by laminating a light guide plate and an optical sheet inside a frame is known (see, for example, Patent Document 1).

JP 2005-158707 A

  However, in the conventional technology, it cannot be said that reduction of rattle noise generated due to the collision between the frame and the optical sheet is considered, and there is room for improvement in terms of reduction of the rattle noise. .

  This invention is made | formed in view of the above, Comprising: It aims at providing the planar illuminating device which can reduce the rattle noise resulting from the collision with a flame | frame and an optical sheet.

  In order to solve the above-described problems and achieve the object, a planar illumination device according to one embodiment of the present invention includes a light guide plate, a frame, and an optical sheet. The light guide plate emits light incident from the side surface from the output surface. The frame surrounds a peripheral portion of the light guide plate. The optical sheet is disposed on the light exit surface side of the light guide plate so as to be surrounded by the frame, and has a spring structure that is elastically deformable at a peripheral edge portion.

  According to one embodiment of the present invention, rattle noise caused by a collision between a frame and an optical sheet can be reduced.

FIG. 1 is a perspective view showing a planar illumination device according to the embodiment. FIG. 2 is a cross-sectional view taken along the line AA in FIG. FIG. 3 is a top view showing the optical sheet and the frame according to the embodiment. FIG. 4 is a top view showing an optical sheet and a frame according to Modification 1 of the embodiment. FIG. 5 is a top view illustrating an optical sheet and a frame according to Modification 2 of the embodiment. FIG. 6 is a top view showing an optical sheet and a frame according to Modification 3 of the embodiment. FIG. 7 is a top view showing an optical sheet and a frame according to Modification 4 of the embodiment. FIG. 8 is a top view showing an optical sheet and a frame according to Modification 5 of the embodiment. FIG. 9 is a top view illustrating an optical sheet and a frame according to Modification 6 of the embodiment. FIG. 10 is a top view illustrating an optical sheet and a frame according to Modification 7 of the embodiment.

  Hereinafter, a planar illumination device according to an embodiment will be described with reference to the drawings. Note that the application of the planar lighting device is not limited by the embodiment described below. It should be noted that the drawings are schematic, and the relationship between the dimensions of each element, the ratio of each element, and the like may differ from the actual situation. Furthermore, there are cases in which parts having different dimensional relationships and ratios are included between the drawings.

(Configuration of planar lighting device)
First, the structure of the planar lighting device 1 according to the embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view showing a planar illumination device 1 according to the embodiment. In the following, in order to clarify the positional relationship, the X axis, the Y axis, and the Z axis that are orthogonal to each other are defined, and the positive direction of the Z axis is the upward direction.

  As shown in FIG. 1, the planar illumination device 1 according to the embodiment includes a frame 20, an upper frame 21, and an optical sheet 30. Here, the frame 20 is a frame located on the lower side in a state where the planar lighting device 1 is placed flat, and the upper frame 21 is a frame located on the upper side.

  An opening 21 a is formed in the upper frame 21. And the light radiate | emitted from the optical sheet 30 is irradiated to the liquid crystal display device which is not shown in figure through the opening part 21a. The planar illumination device 1 according to the embodiment is used as a backlight of such a liquid crystal display device. Such a liquid crystal display device is used, for example, in a car navigation system mounted on a vehicle.

  FIG. 2 is a cross-sectional view taken along the line AA in FIG. As shown in FIG. 2, the planar illumination device 1 includes a light guide plate 10, a frame 20, an upper frame 21, an optical sheet 30, and a reflection plate 40.

  The light guide plate 10 is formed in a rectangular shape in plan view and is made of a transparent material (for example, polycarbonate resin). The light guide plate 10 has two main surfaces on the outer surface and side surfaces on which LEDs (not shown) are arranged close to each other. Light emitted from the LED is incident on the side surface.

  One main surface 10a of the two main surfaces of the light guide plate 10 is an emission surface from which light incident from the side surface is emitted. Therefore, in the following description, “main surface 10a” is referred to as “outgoing surface 10a”.

  For example, an optical path changing pattern composed of a plurality of dots is formed on the main surface 10b of the light guide plate 10 opposite to the exit surface 10a. By forming such an optical path changing pattern, the traveling direction of light traveling through the light guide plate 10 is changed, and light is emitted from the emission surface 10a. As described so far, the planar illumination device 1 according to the embodiment is a so-called edge light type illumination device.

  The frame 20 includes a bottom plate portion 20a and a frame portion 20b. The bottom plate portion 20 a is a flat plate having the same shape as the light guide plate 10. The frame portion 20b is formed so as to protrude upward from the peripheral edge portion of the bottom plate portion 20a so as to surround the light guide plate 10, the optical sheet 30, and the reflection plate 40.

  And the light-guide plate 10, the optical sheet 30, and the reflecting plate 40 are arrange | positioned in the space formed by this bottom plate part 20a and the frame part 20b. For example, as shown in FIG. 2, the reflecting plate 40, the light guide plate 10, and the optical sheet 30 are stacked in order from the bottom plate portion 20 a in a space formed by the bottom plate portion 20 a and the frame portion 20 b.

  The upper frame 21 has a frame shape and is locked on the frame portion 20 b of the frame 20.

  The optical sheet 30 is disposed on the light exit surface 10 a side of the light guide plate 10 so as to be surrounded by the frame portion 20 b of the frame 20. The optical sheet 30 includes a first sheet 30a having a first layer, a second sheet 30b having a second layer, and a third sheet 30c having a third layer, counted from the emission surface 10a of the light guide plate 10.

  For example, the first sheet 30a is a diffusion sheet, the second sheet 30b is a prism sheet, and the third sheet 30c is a DBEF (Dual Brightness Enhancement Film). In the embodiment, the first sheet 30a, the second sheet 30b, and the third sheet 30c have substantially the same shape in plan view.

  A predetermined gap G is formed between the peripheral edge portion 31 of the optical sheet 30 and the frame portion 20 b of the frame 20. By forming the gap G, contact between the optical sheet 30 and the frame 20 can be suppressed even when the optical sheet 30 expands in a high temperature environment. The optical sheet 30 is not bonded to the light guide plate 10.

  The reflection plate 40 is provided between the main surface 10 b of the light guide plate 10 and the bottom plate portion 20 a of the frame 20. The reflection plate 40 travels through the light guide plate 10, reflects the light leaked from the main surface 10 b, and returns it to the light guide plate 10 again.

(Configuration of optical sheet)
Next, the configuration of the optical sheet 30 according to the embodiment will be described with reference to FIG. FIG. 3 is a top view showing the optical sheet 30 and the frame 20 according to the embodiment, specifically, a top view showing the optical sheet 30 and the frame 20 in a state where the upper frame 21 is not disposed. . In order to facilitate understanding of the configuration of the optical sheet 30, the frame 20 is indicated by a broken line in FIG.

  As shown in FIG. 3, the optical sheet 30 according to the embodiment has a spring structure 32 at the peripheral edge 31. The spring structure 32 includes a slit 32a, a band portion 32b, and a support portion 32c.

  The slit 32 a is formed along the peripheral edge 31. The band part 32 b is a band-shaped part formed between the slit 32 a and the end part of the optical sheet 30. The support portion 32 c is a portion that supports the belt portion 32 b on the central portion of the optical sheet 30.

  In the optical sheet 30 provided with such a spring structure 32, the impact due to the collision is transmitted to the entire optical sheet 30 even when the peripheral portion 31 collides with the frame portion 20 b of the frame 20 due to the elastic deformation of the band portion 32 b. This can be suppressed.

  Therefore, according to the embodiment, the rattle noise caused by the collision between the frame 20 and the optical sheet 30 can be reduced.

  In the embodiment, the spring structure 32 capable of elastic deformation can be formed by forming the slit 32 a having a simple shape in the optical sheet 30. Therefore, according to the embodiment, by forming the slit 32 a in the optical sheet 30, the spring structure 32 that can be elastically deformed can be easily formed in the optical sheet 30.

  In the embodiment, since the optical sheet 30 is not bonded to the light guide plate 10 at the peripheral edge 31 or the like, the area from the central portion of the optical sheet 30 to the formation of the slit 32a in the peripheral edge 31 is planar illumination. It can be used as the device 1. Therefore, according to the embodiment, it is possible to realize a narrow frame of the planar illumination device 1.

  Further, in the embodiment, an adhesive or the like is not necessary, and the weight of the optical sheet 30 is reduced by forming the slit 32a, so that the planar lighting device 1 can be reduced in weight.

  In the embodiment, when the optical sheet 30 has a rectangular shape in plan view, the spring structure 32 may be provided on all four sides of the optical sheet 30. Thereby, even if an impact is applied to the planar illumination device 1 in any direction, the peripheral portion 31 of all four sides can be elastically deformed, so that the rattle caused by the collision between the frame 20 and the optical sheet 30 can be obtained. Noise can be further reduced.

  On the other hand, when the optical sheet 30 is rectangular in plan view, it is not always necessary to provide the spring structure 32 on all four sides of the optical sheet 30. For example, by providing the spring structure 32 on at least one of the four sides of the optical sheet 30, rattle noise caused by the collision between the frame 20 and the optical sheet 30 can be reduced.

  Further, when the spring structure 32 is provided on one of the four sides of the optical sheet 30, the spring structure 32 may be provided on the long side, or the spring structure 32 may be provided on the short side.

  Furthermore, in the embodiment, since the predetermined gap G is formed between the frame portion 20b of the frame 20 and the peripheral edge portion 31 of the optical sheet 30, even when the optical sheet 30 expands in a high temperature environment, Contact between the optical sheet 30 and the frame 20 can be suppressed.

  Therefore, according to the embodiment, when the optical sheet 30 expands in a high temperature environment, the optical sheet 30 can be prevented from wrinkling due to contact with the frame 20.

  In addition, the spring structure 32 should just be provided in the at least 1 sheet of optical sheet 30 among the several (3 sheets in the embodiment) optical sheet 30 provided in the planar illumination device 1. For example, when the spring structure 32 is provided by narrowing down the target among the plurality of optical sheets 30, the spring structure 32 is provided on the optical sheet 30 (for example, the third sheet 30 c that is DBEF) that is thickest and easily generates large rattle noise. May be provided. Moreover, the spring structure 32 may be provided in all the optical sheets 30.

  In the example of FIG. 3 described so far, both end portions of the band portion 32b are supported by the support portion 32c. However, the support position by the support part 32c is not restricted to the both ends of the band part 32b. FIG. 4 is a top view showing the optical sheet 30 and the frame 20 according to Modification 1 of the embodiment.

  As shown in the example of FIG. 4, in the spring structure 32, the center portion of the band portion 32 b may be supported by the support portion 32 c (hereinafter, the spring structure 32 shown in FIG. 4 is also referred to as “cantilever structure”). ). Thus, by supporting the central part of the band part 32b by the support part 32c, the elastic deformation of the band part 32b at the four corners of the optical sheet 30 can be facilitated.

  Therefore, according to the example of FIG. 4, rattle noise when the four corners of the optical sheet 30 collide with the frame 20 can be reduced.

  In the example shown in FIG. 3 and FIG. 4, an example in which the support portion 32 c supports the center portion or both end portions of the band portion 32 b is shown, but the portion supported by the support portion 32 c is the center portion of the band portion 32 b or It is not limited to both ends.

  For example, both the center portion and both end portions of the band portion 32b may be supported by the support portion 32c, or portions other than the center portion and both end portions of the band portion 32b may be supported by the support portion 32c. The band 32b may be supported at any position as long as desired elastic deformation is possible in the band 32b and the band 32b can be sufficiently supported.

  FIG. 5 is a top view showing the optical sheet 30 and the frame 20 according to Modification 2 of the embodiment. In the example of FIG. 5, the spring structure 32 has a protrusion 32 d that is formed adjacent to the slit 32 a and protrudes outward from the peripheral edge 31 of the optical sheet 30. For example, the protrusion 32d is provided on the belt portion 32b and is provided apart from the support portion 32c.

  By providing the protrusion 32d, the optical sheet 30 can collide with the frame 20 at a location where the elastic deformation of the band portion 32b is easy (for example, a location away from the support portion 32c). That is, the protrusion 32d can control the collision point between the optical sheet 30 and the frame 20 to a point where elastic deformation is easy. Therefore, according to the example of FIG. 5, the rattle noise can be effectively reduced.

  Further, in the example of FIG. 5, the example in which the protrusion 32 d that controls the collision point between the optical sheet 30 and the frame 20 is provided on the optical sheet 30, but the protrusion is not limited to being provided on the optical sheet 30. .

  FIG. 6 is a top view illustrating the optical sheet 30 and the frame 20 according to the third modification of the embodiment. In order to facilitate understanding of the configuration of the frame 20, in FIG. 6, the optical sheet 30 instead of the frame 20 is indicated by a broken line.

  In the example of FIG. 6, the frame portion 20 b of the frame 20 has a protrusion 20 c that protrudes toward the peripheral edge portion 31 of the optical sheet 30. The protrusion 20c is provided, for example, toward the band portion 32b of the spring structure 32 and is provided away from the support portion 32c.

  By providing the projections 20c, the optical sheet 30 can collide with the frame 20 at a location where the elastic deformation in the band portion 32b is easy as in the example of FIG. Therefore, according to the example of FIG. 6, the rattle noise can be effectively reduced.

  In the example shown in FIG. 5 and FIG. 6, an example in which one protrusion 32 d or protrusion 20 c is provided for each spring structure 32 on each side is shown, but the protrusion 32 d or protrusion 20 c provided for each spring structure 32. Is not limited to one, and two or more protrusions 32d or protrusions 20c may be provided for each side.

  In the example shown in FIG. 5 and FIG. 6, the example in which the projection for controlling the collision point is provided on the optical sheet 30 or the frame 20 is shown, but the projection is provided on both the optical sheet 30 and the frame 20. It may be.

  In the example described so far, the example in which the spring structure 32 is configured by forming the slit 32a has been described, but the spring structure may be configured by other than the slit 32a. FIG. 7 is a top view showing the optical sheet 30 and the frame 20 according to Modification 4 of the embodiment.

  In the example of FIG. 7, the spring structure 33 is composed of a plurality of notches 33a and a plurality of protrusions 33b. The plurality of notches 33 a are formed side by side along the peripheral edge 31. The plurality of convex portions 33b are portions formed between adjacent cutout portions 33a.

  In the example of FIG. 7, the protrusions 33 b can be elastically deformed by forming the plurality of notches 33 a at predetermined intervals so that the protrusions 33 b have a predetermined width. Thereby, similarly to the above-described spring structure 32, even in the spring structure 33, when the optical sheet 30 collides with the frame portion 20 b of the frame 20, it is possible to suppress the impact due to the collision from being transmitted to the entire optical sheet 30. Can do.

  Therefore, according to the example of FIG. 7, rattle noise caused by the collision between the frame 20 and the optical sheet 30 can be reduced.

  In the example of FIG. 7, the spring structure 33 that can be elastically deformed can be formed by forming the notch 33 a having a simple shape in the optical sheet 30. Therefore, according to the embodiment, by forming the notch 33 a in the optical sheet 30, the spring structure 33 that can be elastically deformed can be easily formed in the optical sheet 30.

  FIG. 8 is a top view showing the optical sheet 30 and the frame 20 according to Modification 5 of the embodiment. Unlike the example shown so far, in the example of FIG. 8, no gap G is formed between the optical sheet 30 and the frame 20.

  And as shown in FIG. 8, the spring structure 32 is provided in 2 sides which adjoin among 4 sides in the optical sheet 30 which is rectangular shape by planar view. For example, a spring structure 32A composed of a slit 32a, a band portion 32b, and a support portion 32c is provided on the long side on the Y axis negative direction side, and a spring structure 32B having the same configuration is a short side on the X axis positive direction side. Provided.

  Here, in the example of FIG. 8, since the gap G is not formed between the optical sheet 30 and the frame 20, the Y axis of the optical sheet 30 is applied by the force 100 applied to the optical sheet 30 from the spring structure 32A. The long side on the positive direction side is pressed against the frame 20. Similarly, the short side on the X axis negative direction side of the optical sheet 30 is pressed against the frame 20 by the force 101 applied to the optical sheet 30 from the spring structure 32B.

  That is, the spring structures 32A and 32B are provided by setting the size such that the gap G is not formed between the optical sheet 30 and the frame 20 and providing the spring structures 32A and 32B on two adjacent sides of the optical sheet 30. Two sides that are not present can be pressed against the frame 20.

  Accordingly, since the optical sheet 30 is supported and fixed by the spring structures 32A and 32B, rattle noise caused by the collision between the frame 20 and the optical sheet 30 can be reduced.

  In the example of FIG. 8, the case where the spring structures 32A and 32B have the structure shown in FIG. 3 is shown, but the spring structures 32A and 32B are not limited to the case shown in FIG.

  FIG. 9 is a top view showing the optical sheet 30 and the frame 20 according to Modification 6 of the embodiment. As shown in the example of FIG. 9, the spring structures 32A and 32B that support the frame 20 by pressing the two sides of the optical sheet 30 may be configured by the cantilevered spring structure 32 shown in the example of FIG. .

  FIG. 10 is a top view illustrating the optical sheet 30 and the frame 20 according to Modification Example 7 of the embodiment. As shown in the example of FIG. 10, the spring structures 33A and 33B that press and support the two sides of the optical sheet 30 against the frame 20 are springs constituted by the notches 33a and the protrusions 33b shown in the example of FIG. The structure 33 may be configured.

  The embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the embodiment, the case where the optical sheet 30 is rectangular has been described, but the optical sheet 30 may not be rectangular.

  For example, when the entire meter panel of the vehicle is configured by a liquid crystal display device, the optical sheet 30 may be formed in a shape corresponding to the shape of the entire meter panel. Further, when the entire meter panel of the vehicle is configured with a liquid crystal display device, when the optical sheet 30 has a side including a curve, the spring structures 32 and 33 may be provided along the curve.

  As described above, the planar illumination device 1 according to the embodiment includes the light guide plate 10, the frame 20, and the optical sheet 30. The light guide plate 10 emits light incident from the side surface from the output surface 10a. The frame 20 surrounds the periphery of the light guide plate 10. The optical sheet 30 is disposed on the light exit surface 10 a side of the light guide plate 10 so as to be surrounded by the frame 20, and has spring structures 32 and 33 that can be elastically deformed at the peripheral edge 31. Thereby, the rattle noise resulting from the collision between the frame 20 and the optical sheet 30 can be reduced.

  In the planar illumination device 1 according to the embodiment, the spring structure 32 has a slit 32 a formed along the peripheral edge 31 of the optical sheet 30. Thereby, the spring structure 32 that can be elastically deformed can be easily formed in the optical sheet 30.

  In the planar illumination device 1 according to the embodiment, the spring structure 32 has a protrusion 32 d that is formed adjacent to the slit 32 a and protrudes outward from the peripheral edge 31 of the optical sheet 30. Thereby, rattle noise can be reduced effectively.

  Further, in the planar illumination device 1 according to the embodiment, the spring structure 33 has a plurality of cutout portions 33 a formed side by side along the peripheral edge portion 31 of the optical sheet 30. Thereby, the spring structure 33 that can be elastically deformed can be easily formed in the optical sheet 30.

  Further, in the planar lighting device 1 according to the embodiment, the frame 20 has a protrusion 20 c that protrudes toward the peripheral edge 31 of the optical sheet 30. Thereby, rattle noise can be reduced effectively.

  In the planar illumination device 1 according to the embodiment, the optical sheet 30 is rectangular in plan view, and the spring structures 32 and 33 are provided on all four sides of the optical sheet 30. Thereby, the rattle noise resulting from the collision between the frame 20 and the optical sheet 30 can be further reduced.

  In the planar illumination device 1 according to the embodiment, the optical sheet 30 has a rectangular shape in plan view, and the spring structures 32 and 33 are provided on two adjacent sides of the optical sheet 30. The two sides where the structures 32 and 33 are not provided are pressed against the frame 20. Thereby, the rattle noise resulting from the collision between the frame 20 and the optical sheet 30 can be reduced.

  Further, the present invention is not limited by the above embodiment. What comprised suitably combining each component mentioned above is also contained in this invention. Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above-described embodiment, and various modifications can be made.

  DESCRIPTION OF SYMBOLS 1 Planar illuminating device, 10 Light guide plate, 20 frame, 20c protrusion, 30 Optical sheet, 31 Peripheral part, 32, 33 Spring structure, 32a Slit, 32b Band part, 32c Support part, 32d Protrusion, 33a Notch part, 33b Convex Part

Claims (7)

A light guide plate that emits light incident from the side surface from the exit surface;
A frame surrounding the periphery of the light guide plate;
An optical sheet having a spring structure that is disposed on the light exit surface side of the light guide plate so as to be surrounded by the frame and elastically deformable at a peripheral edge portion;
A planar lighting device.   The planar illumination device according to claim 1, wherein the spring structure has a slit formed along the peripheral edge of the optical sheet.   The planar illumination device according to claim 2, wherein the spring structure includes a protrusion that is formed adjacent to the slit and protrudes outward from the peripheral edge portion of the optical sheet.   The planar illumination device according to claim 1, wherein the spring structure has a plurality of cutout portions formed side by side along the peripheral edge portion of the optical sheet.   The planar illumination device according to any one of claims 1 to 4, wherein the frame has a protrusion protruding toward the peripheral edge of the optical sheet. The optical sheet is rectangular in plan view,
The planar illumination device according to any one of claims 1 to 5, wherein the spring structure is provided on all four sides of the optical sheet. The optical sheet is rectangular in plan view,
The surface according to any one of claims 1 to 5, wherein the spring structure is provided on two adjacent sides of the optical sheet, and the two sides of the optical sheet on which the spring structure is not provided are pressed against the frame. Illuminator.

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