Display device

Abstract

To provide a display device for easily positioning an optical sheet and improving working efficiency.SOLUTION: A backlight unit 100 of a liquid crystal display device includes: a recessed case body 110 for housing a backlight; an optical sheet 50 disposed in an opening of the case body 110; and a stepped screw 120 for fixing the optical sheet 50 to the case body 110. In the optical sheet 50, a penetrated long hole 60 is formed in one end, and a penetrated round hole 62 is formed in the other end that opposes the one end. In the case body 110, a screw hole 116 corresponding to each of the long hole 60 and the round hole 62 is formed. The stepped screw 120 is clamped to the screw hole 116 via the long hole 60 and the round hole 62.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a display device, and more particularly to the positioning of an optical sheet in a backlight unit of a liquid crystal display device. [Background technology]

[0002] A liquid crystal display device includes a liquid crystal module and a backlight housed in a housing, and an optical sheet is arranged on the back side of the liquid crystal module to control the light irradiated from the backlight to the liquid crystal module. The optical sheet is made of resin and is susceptible to thermal expansion and contraction due to temperature changes.

[0003] Patent Document 1 discloses a liquid crystal display device that reduces the amount of expansion of the optical sheet due to thermal changes while narrowing the frame of the device. Figure 1 is a partial cross-sectional view of the liquid crystal display device of Patent Document 1, in which a buffer section 2a consisting of a curved or inclined surface is formed in a front cabinet 2 that covers the peripheral edge of a liquid crystal module 10, which is made up of a laminated liquid crystal panel 3 and an optical sheet 6, and the optical sheet 6 is expanded in an oblique direction. The display device of Patent Document 2 forms positioning pins on the housing and positions the optical sheet by inserting the pins into holes in the optical sheet. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-21220 [Patent Document 2] International Publication No. 2011 / 093119 Summary of the Invention [Problem to be solved by the invention]

[0005] Figure 2(A) is a schematic plan view of a backlight unit of a conventional liquid crystal display device, Figure 2(B) is a plan view of an optical sheet, Figures 2(C) and (D) are enlarged views of parts A and B of the optical sheet, and Figure 3 is a schematic enlarged cross-sectional view of part B of the optical sheet.

[0006] The backlight unit includes a generally rectangular, concave case body 30, with multiple direct-type backlight cases 40 arranged in the central region of the case body 30, and a generally rectangular optical sheet 50 attached above them. The optical sheet 50 includes a laminate of a light guide plate 52, a diffusion sheet 54, a prism sheet 56, and a light-reflecting prism sheet 58, and the light guide plate 52 irradiates light from the backlight toward the liquid crystal panel. The layers of the optical sheet 50 may be bonded together with an adhesive, or may simply be in close contact without using an adhesive.

[0007] As shown in FIG. 2(C), a positioning slot 60 is formed in part A at the upper end of the optical sheet 50, penetrating each layer. Furthermore, as shown in FIG. 2(D), a positioning circular hole 62 is formed in part B at the lower end of the optical sheet 50, penetrating each layer. Meanwhile, a cylindrical upper protrusion 70 is formed in part A on the outer edge of the case body 30, and a cylindrical lower protrusion 72 is formed in part B. When attaching the optical sheet 50 to the case body 30, the upper protrusion 70 is inserted into the slot 60, and the lower protrusion 72 is inserted into the round hole 62. Furthermore, a jump-out prevention member 80 is attached to the stepped portion 32 of the case body 30 to prevent the optical sheet 50 from jumping out. The jump-out prevention member 80 is, for example, a thin plate-like member, and is fixed to the stepped portion 32 with an adhesive or double-sided tape.

[0008] The oblong hole 60 has a generally elliptical shape and is disposed so that its major axis is parallel to the longitudinal direction of the case body 30 (the vertical direction in the drawing). The minor axis of the oblong hole 60 is generally equal to or slightly larger than the outer diameter of the upper protrusion 70, and the major axis is sufficiently larger than the outer diameter of the upper protrusion 70. Meanwhile, the inner diameter of the round hole 62 is generally equal to or slightly larger than the outer diameter of the lower protrusion 72. When attaching the optical sheet 50 to the case body 30, the round hole 62 positions the optical sheet 50 in the vertical and horizontal directions, and the oblong hole 60 functions as a rotation stopper for the optical sheet 50.

[0009] Such conventional optical sheet positioning structures have the following problems. To improve positioning accuracy, it is desirable to reduce the amount of backlash, which is the difference between the radial size of the elongated holes 60 / round holes 62 in the optical sheet 50 and the radial size of the upper protrusions 70 / lower protrusions 72. However, reducing the amount of backlash makes it difficult to position the optical sheet 50. Furthermore, due to the thickness constraints of the backlight unit, it is difficult to make the upper protrusions 70 / lower protrusions 72 taller than necessary. If the height of the upper protrusions 70 / lower protrusions 72 is approximately the same as the height of the top layer 58 of the optical sheet 50, there is insufficient guidance when assembling the optical sheet 50 onto the upper protrusions 70 / lower protrusions 72, resulting in poor assembly workability. Furthermore, if the positioning points of the optical sheet 50 are spaced apart on both ends, the optical sheet 50 is likely to come off the upper protrusions 70 / lower protrusions 72 due to vibration or warpage of the components. For example, the top layer 58 may move into the small gap between the upper protrusions 70 / lower protrusions 72 and the anti-pop-out member 80.

[0010] The present invention has been made to solve the above-mentioned problems of the prior art, and has an object to provide a display device that facilitates the positioning of an optical sheet and improves work efficiency. [Means for solving the problem]

[0011] The display device of the present invention includes a case body that houses a backlight, an optical sheet that is placed on the case body, and first and second screw members for fixing the optical sheet to the case body, wherein a first positioning hole is formed at one end of the optical sheet and a second positioning hole is formed at the other end opposite the one end, and first and second screw holes corresponding to the first and second positioning holes are formed in the case body, and the first screw member is fastened to the first screw hole via the first positioning hole and the second screw member is fastened to the second screw hole via the second positioning hole.

[0012] In one embodiment, the first and second screw members each have a body portion extending in the axial direction and a threaded portion connected to the body portion via a tapered portion. In one embodiment, the display device further includes a mechanism for preventing the first and second screw members from popping out.

[0013] The display device of the present invention further includes a case body that houses a backlight, an optical sheet that is placed on the case body, and first and second resin pins for fixing the optical sheet to the case body, wherein a first positioning hole is formed at one end of the optical sheet and a second positioning hole is formed at the other end opposite the one end, and first and second through holes corresponding to the first and second positioning holes are formed in the case body, and the end of the first resin pin that is inserted into the first through hole through the first positioning hole is thermally fixed, and the end of the second resin pin that is inserted into the second through hole through the second positioning hole is thermally fixed.

[0014] In one embodiment, the first resin pin includes a main body having an elliptical cross section, and the amount of play between the first resin pin and the first positioning hole is adjusted by rotating the first resin pin. In one embodiment, the first and second resin pins each have a main body extending in the axial direction and an elongated end connected to the main body via a tapered portion, and the elongated end is inserted into the first or second through hole, and the elongated end exposed in the first or second through hole is thermally caulked with a welding resin. In one embodiment, the display device further includes a mechanism for preventing the first and second resin pins from popping out. [Effects of the Invention]

[0015] According to the present invention, the optical sheet is positioned and fixed to the case body using screw members or resin pins, so that the optical sheet can be fixed without being limited by its thickness and furthermore, displacement due to vibration or warping of the optical sheet can be prevented. Furthermore, when the screw members or resin pins are inserted into the positioning holes of the optical sheet, the tapered portions of the screw members or resin pins guide them in, improving the ease of assembly. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 10 is a partial cross-sectional view of a conventional liquid crystal display device. [Figure 2] Figure 2(A) is a schematic plan view of a backlight case of a conventional liquid crystal display device, Figure 2(B) is a plan view of an optical sheet, and Figures 2(C) and 2(D) are enlarged views of parts A and B of the optical sheet. [Figure 3] 3 is a schematic enlarged cross-sectional view of a portion B of the conventional optical sheet mounting structure shown in FIG. 2. FIG. [Figure 4] 1 is a schematic cross-sectional view of a backlight unit of a liquid crystal display device according to a first embodiment of the present invention. [Figure 4A] 1 is a schematic cross-sectional view showing a state in which an optical sheet according to a first embodiment of the present invention is attached to a case body. [Figure 5] FIG. 10 is a schematic cross-sectional view of a backlight unit of a liquid crystal display device according to a second embodiment of the present invention. [Figure 6] FIG. 10 is a schematic cross-sectional view showing a modified example of the first embodiment. [Figure 7] FIG. 10 is a schematic cross-sectional view showing a modified example of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of the present invention will be described. The display device of the present invention is applied to a liquid crystal display device including a liquid crystal module and a backlight unit. The liquid crystal display device may be equipped with a touch panel function as a user interface, or a function for detecting the approach of a user's finger or the like using infrared rays or the like. [Example]

[0018] Next, an embodiment of the present invention will be described with reference to the drawings. Note that the scale of the drawings is exaggerated to facilitate understanding of the invention, and does not necessarily represent the scale of an actual product.

[0019] Fig. 4 is a schematic cross-sectional view of a backlight unit of a display device according to an embodiment of the present invention, in which the same reference numerals are used to designate the same components as those shown in Fig. 3. The backlight unit 100 of this embodiment is included in a liquid crystal display device, and a liquid crystal module (such as a polarizing plate and a liquid crystal panel), a cover glass, etc. (not shown) are mounted on top of the backlight unit 100.

[0020] The backlight unit 100 includes a case body 110, an optical sheet 50, and shoulder screws 120 for fixing the optical sheet 50 to the case body 110. The case body 110 is, for example, a concave housing having a rectangular bottom 112 and four side walls 114 connected to the bottom 112, and the optical sheet 50 is attached to an opening formed by the four side walls 114. For example, as shown in FIG. 2 , the case body 110 houses a plurality of direct-type backlight cases 40, but is not limited to this and may also house an edge-light type backlight. In the latter case, a light source such as an LED is disposed in the case body 110 so as to face the end face of the light guide plate 52 of the optical sheet 50.

[0021] 2 and 3, and is configured by laminating a rectangular light guide plate 52, a rectangular diffusion sheet 54, a rectangular prism sheet 56, and a rectangular light reflecting prism sheet 58. A long hole 60 for positioning is formed through the protruding region at the center of the upper end of the optical sheet 50, and a round hole 62 for positioning is formed through the protruding region at the center of the lower end.

[0022] Two screw holes 116 are formed in the bottom 112 of the case body 110, corresponding to the elongated hole 60 and the round hole 62 of the optical sheet 50. In addition, a step 118 for fixing the jump-out prevention member 80 is formed in the side wall 114.

[0023] As shown in FIG. 4(B), the shoulder screw 120 has a circular head 122, a cylindrical body 124 that is smaller in diameter than the head 122 and extends in the axial direction, a tapered portion (stepped portion) 126 connected to the body 124, and a threaded portion 128 connected to the tapered portion 126. The body 124 has an outer diameter D that is slightly smaller than the inner diameter of the circular hole 62 in the optical sheet 50, and a length L that is approximately equal to or slightly greater than the thickness of the optical sheet 50. The slope of the tapered portion 126 functions as a guide to guide the shoulder screw 120 when it is inserted into the elongated hole 60 / circular hole 62 in the optical sheet 50. The threaded portion 128 has an outer diameter smaller than that of the body 124, and engages with the threaded hole 116 in the case body 110 when the shoulder screw 120 is used to fix the optical sheet 50.

[0024] Next, a method for attaching the optical sheet 50 to the case body 110 will be described. First, the optical sheet 50 is placed in the opening of the case body 110, and the oblong hole 60 and the round hole 62 are aligned with the screw holes 116 of the case body 110, respectively. Next, as shown in FIG. 4(A), shoulder screws 120 are inserted into the oblong holes 60 and the round holes 62, respectively. At this time, the shoulder screws 120 advance through the oblong holes 60 and the round holes 62 of the optical sheet 50 while being guided by the tapered portions 126, until the threaded portions 128 reach the screw holes 116.

[0025] Next, shoulder screw 120 is rotated until head 122 comes into contact with top layer 58 of optical sheet 50 and is at approximately the same height as step portion 118, as shown in FIG. 4A. Next, pop-out prevention member 80 is fixed to step portion 118. At this time, pop-out prevention member 80 is either in general contact with head 122 or has a small gap between it and head 122.

[0026] As described above, according to this embodiment, the optical sheet 50 is positioned and fixed to the case body 110 using the shoulder screws 120, so the optical sheet can be easily positioned regardless of the thickness of the backlight unit, and the assembly workability can be improved by utilizing the guide provided by the tapered portions 126 of the shoulder screws 120. Furthermore, because the optical sheet is fastened using a screw mechanism, it is possible to prevent the optical sheet from becoming misaligned due to vibration of the optical sheet or warping of parts, even if the positioning points are far apart.

[0027] Next, a second embodiment of the present invention will be described. Fig. 5 is a schematic cross-sectional view of a backlight unit of a liquid crystal display device according to the second embodiment. In the second embodiment, stepped resin pins are used to position and fix the optical sheet to the case body, instead of the shoulder screws 120 of the first embodiment.

[0028] The backlight unit 200 of the second embodiment includes a case body 210, a resin pin 220 for positioning and fixing, and a jump-out prevention member 80. The case body 210 is configured in a similar manner to the case body 110 of the first embodiment, but in the second embodiment, a cylindrical through-hole 216 is formed in the bottom portion 212 instead of the screw hole 116.

[0029] 5(B), the resin pin 220 has a circular head 222, a cylindrical main body 224 that is smaller in diameter than the head 222 and extends in the axial direction, a tapered portion (stepped portion) 226 connected to the main body 224, and an elongated end portion 228 connected to the tapered portion 226. The resin pin 220 is made of, for example, polycarbonate, ABS resin, or the like.

[0030] The main body 224 has an elliptical cross-sectional shape in a horizontal direction perpendicular to the axial direction. The major axis of the ellipse of the main body 224 is smaller than the major axis of the elliptical oblong hole 60 but larger than the minor axis, and the major and minor axes of the ellipse of the main body 224 are smaller than the inner diameter of the circular hole 62. The axial length L1 of the outer portion 224 is approximately equal to or slightly larger than the thickness of the optical sheet 50. As in the first embodiment, the inclination of the tapered portion 226 functions as a guide to guide the resin pin 220 when it is inserted into the oblong hole 60 / circular hole 62 of the optical sheet 50.

[0031] The elongated end 228 has a circular cross section in a horizontal direction perpendicular to the axial direction, and its diameter is slightly smaller than the inner diameter of the through-hole 216 of the case body 210. The axial length L2 of the elongated end 228 is slightly larger than the length of the through-hole 216 of the case body 210.

[0032] Next, a method for attaching the optical sheet 50 to the case body 210 will be described. First, the optical sheet 50 is placed in the opening of the case body 210, and the oblong holes 60 and round holes 62 of the optical sheet 50 are aligned with the through holes 216 of the case body 210, respectively. Next, the resin pins 220 are inserted into the oblong holes 60 and round holes 62, respectively. The resin pins 220 inserted into the round holes 62 may face in any direction because the major diameter of the main body 224 is smaller than the inner diameter of the round holes 62, but the resin pins 220 inserted into the oblong holes 60 are inserted so that the major diameter of the main body 224 faces the major diameter direction of the oblong holes 60.

[0033] Resin pin 220 advances through elongated hole 60 and round hole 62 in optical sheet 50 while being guided by tapered portion 226 until tapered portion 226 abuts against bottom portion 212. At this time, the tip of elongated end portion 228 inserted into through-hole 216 protrudes slightly from the surface of case body 210.

[0034] Next, by rotating resin pin 220 inserted into elongated hole 60, main body 224 is brought into contact with the inner periphery of elongated hole 60, the amount of play between elongated hole 60 and resin pin 220 is adjusted, and optical sheet 50 is positioned with high precision. Next, elongated end 228 protruding from bottom 212 of case body 210 is thermally caulked or thermally compressed using, for example, circular welding resin 230, thereby fixing resin pin 220 to case body 210.

[0035] According to this embodiment, the optical sheet 50 can be positioned and fixed to the case body 210 by thermally caulking the resin pins 220. Furthermore, when shoulder screws are used as in the first embodiment, chips and swarf are generated as the screws turn, which can contaminate the backlight unit. However, by using bonding by thermal caulking or thermocompression bonding as in this embodiment, the generation of chips and swarf can be prevented, and the backlight unit can be kept clean.

[0036] Next, modified examples of the first and second embodiments will be described. Fig. 6 shows a modified example of the first embodiment, and Fig. 7 shows a modified example of the second embodiment. In the first and second embodiments, the flat, thin plate-like jump-out prevention member 80 is placed above the shoulder screw 120 or the resin pin 220, but the jump-out prevention member 300 of the modified example is attached between the shoulder screw 120 and the optical sheet 50, or between the resin pin 220 and the optical sheet 50, and the jump-out prevention member 300 is positioned and fixed together with the optical sheet 50.

[0037] 6(B), the anti-jump-out member 300 has a generally circular outer shape and includes a peripheral portion 310 and a central portion 320 recessed from the peripheral portion 310. The central portion 320 has a flat surface that is larger than the head 122 of the shoulder screw 120, and the central portion 320 has a through-hole 330 that is slightly larger in diameter than the main body portion 224, so that the main body portion 224 of the shoulder screw 220 can be inserted into the central portion 320. The step between the peripheral portion 310 and the central portion 320 is approximately equal to the thickness of the head 122 of the stepped screw 120.

[0038] The optical sheet 50 is positioned within the opening of the case body 110 so that the elongated holes 60 and round holes 62 of the optical sheet 50 are aligned with the screw holes 116 of the case body 110. Next, the jump-out prevention member 300 is positioned on the optical sheet 50 so that the through-holes 330 are aligned with the elongated holes 60 and round holes 62, respectively. Next, the shoulder screws 120 are inserted into the through-holes 330 of the jump-out prevention member 300 and the elongated holes 60 / round holes 62 of the optical sheet 50, so that the heads 122 abut against the flat surface of the center portion 320 of the jump-out prevention member 300. Next, the shoulder screws 120 are rotated to tighten the threaded portions 128 into the screw holes 116 of the case body 110. When the optical sheet 50 is fixed to the case body 110 by the shoulder screw 120, the peripheral portion 310 of the anti-pop-out member 300 contacts or presses against the step portion 118 of the case body 110, and the surface of the peripheral portion 310 roughly coincides with the surface of the head 122 of the shoulder screw 120.

[0039] According to this modification, by disposing the anti-pop-out member 300 between the shoulder screw 120 and the optical sheet 50, or between the resin pin 220 and the optical sheet 50, the anti-pop-out member 300 can be positioned and fixed together with the optical sheet 50. Furthermore, by recessing the center of the anti-pop-out member 300, the backlight unit 100 / 200 can be made thinner.

[0040] In the above embodiment, the oblong hole 60 and the round hole 62 are exemplified as the positioning holes of the optical sheet, but the positioning holes may each be an oblong hole, each may be a round hole, or may have a hole of another shape. Also, in the above embodiment, the resin pin is thermally caulked or thermocompression bonded to the welding resin, but the resin pin may also be fixed using laser welding or other thermal bonding means.

[0041] Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications and changes are possible within the scope of the gist of the invention described in the claims. [Explanation of symbols]

[0042] 50: Optical sheet 60: Slot 62: Round hole 80: Anti-jumping part 100, 100A, 200, 200A: Backlight unit 110, 210: Case body 112, 212: Bottom 114, 214: Side wall portion 116: Screw hole 118, 218: Stepped part 120: Stepped screw 200: Resin pin 230: Heat-welded material

Claims

1. a case body that houses a backlight; an optical sheet disposed on the case body; first and second screw members for fixing the optical sheet to the case body; a first positioning hole is formed at one end of the optical sheet, and a second positioning hole is formed at the other end opposite to the first end; The case body is formed with first and second screw holes corresponding to the first and second positioning holes, A display device, wherein a first screw member is fastened to a first screw hole via a first positioning hole, and a second screw member is fastened to a second screw hole via a second positioning hole.

2. 2. The display device according to claim 1, wherein each of the first and second screw members has a main body portion extending in the axial direction and a threaded portion connected to the main body portion via a tapered portion.

3. The display device according to claim 1 , further comprising a mechanism for preventing the first and second screw members from popping out.

4. a case body that houses a backlight; an optical sheet disposed on the case body; first and second resin pins for fixing the optical sheet to the case body; a first positioning hole is formed at one end of the optical sheet, and a second positioning hole is formed at the other end opposite to the first end; The case body is formed with first and second through holes corresponding to the first and second positioning holes, A display device in which an end of a first resin pin inserted into a first through hole via a first positioning hole is thermally fixed, and an end of a second resin pin inserted into a second through hole via a second positioning hole is thermally fixed.

5. The display device according to claim 4, wherein the first resin pin includes a main body portion having an elliptical cross section, and the amount of play between the first resin pin and the first positioning hole is adjusted by rotating the first resin pin.

6. The display device described in claim 4, wherein each of the first and second resin pins has a main body portion extending in the axial direction and an elongated end portion connected to the main body portion via a tapered portion, the elongated end portion being inserted into the first or second through hole, and the elongated end portion exposed in the first or second through hole being thermally crimped with a welding resin.

7. The display device according to claim 4 , further comprising a mechanism for preventing the first and second resin pins from popping out.

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