JP2007256385A - Optical sheet unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To avoid bending and wrinkling of an optical sheet. <P>SOLUTION: An optical sheet unit 20 is such that a plurality of translucent optical sheets 22 are held in a stacked state by a holding member 23. The respective optical sheets 22 have holding holes 24, linked to one another in the stacked state, respectively. The holding member 23 comprises a shaft part 25 inserted into the respective holding holes 24 and a pair of lock parts 26 which project from both ends of the shaft part 25 in directions crossing its axis. The holding member 23 is so formed that the shaft part 25 is sized forming a clearance for the diameter of the holding holes 24 and both the lock parts 26 have a mutual distance giving a clearance for the total thickness of the stacked optical optical units 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical sheet unit.

  The liquid crystal display device has a configuration in which a liquid crystal panel and a backlight as an external light source are assembled. Among these, the backlight contains a large number of linear light sources such as cold cathode tubes in a box-shaped case with an opening on the liquid crystal panel side, and converts the light emitted from each linear light source into a planar shape at the opening of the case. It is set as the structure provided with the some optical sheet which has the effect | actions of doing.

  In assembling the above-described backlight in the manufacturing process of the liquid crystal display device, the optical sheets are sequentially stacked after the linear light sources are installed in the case. At this time, there is a possibility that the order of stacking the optical sheets may be wrong, the optical sheets may be excessive or insufficient, and foreign substances such as dust may be caught between the optical sheets.

Therefore, it is conceivable to use an optical sheet unit that is integrated in a state where the optical sheets are laminated in advance. In this apparatus, each optical sheet is fixed by press-fitting a hook-shaped fixing bracket in a state where the optical sheets are laminated.
JP 7-43713 A

  However, since the optical sheets are different in material, thickness, and the like, there may be a difference in the expansion / contraction rate due to temperature change. When each optical sheet is fixed by press-fitting a fixing bracket as described above, a temperature change occurs in the backlight as the liquid crystal display device is used, and each optical sheet expands (expands) or contracts. At times, there is a concern that the optical sheet may be bent or wrinkled.

  The present invention has been completed based on the above circumstances, and an object thereof is to avoid the occurrence of bending and wrinkling in an optical sheet.

  In the present invention, a plurality of optical sheets having translucency are held by a holding member in a stacked state, and each of the optical sheets is provided with a holding hole capable of communicating with each other in a stacked state. On the other hand, the holding member includes a shaft portion inserted into each holding hole, and a pair that protrudes from both end portions of the shaft portion in a direction intersecting the axial direction and can be locked to the periphery of the holding hole. The holding member has a diameter dimension of the shaft portion having a clearance with respect to a diameter dimension of each holding hole, and a distance between the both locking parts is laminated. The optical sheet is formed so as to have a clearance with respect to the total thickness dimension of the optical sheets.

  If it does in this way, while the axial part of a holding member will be inserted in each holding hole which was mutually connected in each laminated optical sheet, both locking parts will be locked to the perimeter of a holding hole, and each optical sheet Are integrally held in a laminated state. The holding member has a clearance with respect to the total thickness of the optical sheet in which the distance between the two locking portions is stacked, and the shaft portion has a clearance with respect to the diameter of each holding hole. Therefore, even if there is a difference in the expansion / contraction rate of each optical sheet due to temperature change, the expansion / contraction of each optical sheet can be allowed.

The following configuration is preferable as an embodiment of the present invention.
(1) The holding member includes a first holding component and a second holding component that have the shaft portion and the locking portion, respectively, and are assembled to each other. The first holding component and the second holding component include It is set as the structure by which the control means which can control the distance between both the latching | locking parts is provided by mutually abutting as it is assembled | attached along the axial direction of the said axial part. This makes it easier to assemble the optical sheet and set the clearance in the axial direction of the shaft portion compared to the case where the holding member is a single part and either one of the locking portions is formed by tapping. Can be ensured and simplified.

(2) The holding member is configured to be provided with a positioning portion for an attachment member to which the optical sheet unit is attached. Thereby, positioning with respect to an attachment member can be aimed at. Since the holding member for holding each optical sheet can also have a positioning function, the structure can be simplified as compared with the case where a positioning structure is provided separately.

  According to the present invention, it is possible to prevent the optical sheet from being bent or wrinkled.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the optical sheet unit 20 constituting the liquid crystal display device 10 will be described. In the following description, the upper side in FIG. 1 is the front side and the lower side is the back side.

  As shown in FIG. 1, the liquid crystal display device 10 is roughly assembled with a liquid crystal panel 11 for displaying an image sandwiched between a backlight 12 on the back side and a bezel 13 having a frame shape on the front side. It is supposed to be configured.

  The liquid crystal panel 11 includes a pair of transparent (translucent) glass substrates 14 and a liquid crystal layer 15 sandwiched between the glass substrates 14. The liquid crystal layer 15 is composed of a liquid crystal that is a substance whose optical characteristics change with the application of an electric field. The two glass substrates 14 are bonded to each other with a predetermined gap therebetween by a spacer, and the liquid crystal layer 15 sandwiched between them is surrounded by a sealant 16 and kept in a liquid-tight state. Yes.

  Among both glass substrates 14, on the inner surface (the surface facing the liquid crystal layer 15) of the glass substrate 14 on the back side, switching elements (for example, TFTs) and pixel electrodes connected to the source wiring and the gate wiring orthogonal to each other, On the inner surface of the front glass substrate 14, R, G, and B color filters are respectively provided in a matrix at positions corresponding to the pixel electrodes. An external signal circuit is connected to each wiring, and a signal for displaying an image is given by the signal circuit. Further, polarizing plates 17 are attached to the outer surfaces of the glass substrates 14 (surfaces opposite to the liquid crystal layer 15).

  The backlight 12 includes a case 18 having a substantially box shape opened toward the front side, a plurality of linear light sources 19 (for example, cold cathode tubes) housed in a parallel state in the case 18, and a case 18 includes an optical sheet unit 20 mounted on the periphery of the opening 18 and a frame-like frame 21 that holds the optical sheet unit 20 between the periphery of the opening of the case 18.

  The optical sheet unit 20 includes a plurality of light-transmitting optical sheets 22 stacked on each other, and a holding member 23 for holding the optical sheets 22 in a stacked state. The optical sheet 22 is a diffusion plate 22a, a diffusion sheet 22b, a lens sheet 22c, and a brightness enhancement sheet 22d in order from the lower side (linear light source 19 side, opposite to the liquid crystal panel 11) shown in FIG. The light emitted from each linear light source 19 by each optical sheet 22 can be irradiated to the liquid crystal panel 11 on the front side in a state in which the light is converted into a planar shape. Each optical sheet 22 is made of a synthetic resin, and may have different thickness dimensions and materials for each type. Further, the outer shapes of the optical sheets 22 are substantially the same. The number and type of the optical sheet 22 can be arbitrarily changed.

  As shown in FIG. 2, each optical sheet 22 is provided with a holding hole 24 through which the holding member 23 passes so as to penetrate each optical sheet 22 in the thickness direction. The holding holes 24 are configured to communicate with each other in a state where the optical sheets 22 are stacked and aligned in the plane direction. Each holding hole 24 is formed in a substantially circular shape. As shown in FIG. 3, the holding holes 24 are respectively installed at four corner positions (each corner) in each optical sheet 22, and a holding member 23 is attached to each. The arrangement positions of the holding hole 24 and the holding member 23 in each optical sheet 22 are outside the display area (active area) of the liquid crystal panel 11 and are set so as not to affect the displayed image. Has been.

  On the other hand, the holding member 23 is made of metal, and as shown in FIG. 2, in the vertical direction (the thickness direction of each optical sheet 22, the direction intersecting (orthogonal) with the surface direction of each optical sheet 22). And a pair of locking portions 26 protruding in the lateral direction (the surface direction of each optical sheet 22 and the direction intersecting (orthogonal to) the axial direction of the shaft portion 25) from both ends of the shaft portion 25. It is composed of Among these, the shaft portion 25 can be inserted into the holding hole 24 of each optical sheet 22 described above. The shaft portion 25 is formed in a substantially cylindrical shape corresponding to the shape of the holding hole 24.

  On the other hand, the locking portion 26 is formed in a hook shape projecting radially outward from the outer peripheral edge at both ends of the shaft portion 25. The locking part 26 is formed in a substantially circular shape in plan view. Since the outer diameter dimension of the locking part 26 is set to be larger than the diameter dimension of the holding hole 24, the optical sheet 22 (brightness enhancement sheet 22 d) arranged on the most front side among the laminated optical sheets 22 and The optical sheet 22 (diffusion plate 22a) arranged on the backmost side can be locked to the peripheral edges of both holding holes 24. Thereby, it can hold | maintain integrally (collectively) in the state which laminated | stacked each optical sheet 22. FIG. Both locking portions 26 are arranged to face each other with a predetermined distance in the vertical direction.

  The diameter dimension of the shaft portion 25 of the holding member 23 is set larger than the diameter dimension of the holding hole 24 by a predetermined dimension so that a predetermined clearance is secured with respect to the holding hole 24. . Therefore, the shaft portion 25 is loosely inserted into the holding hole 24. On the other hand, the distance between the upper and lower locking portions 26 of the holding member 23 is the total thickness dimension of each optical sheet 22 (from the surface exposed on the back side when each optical sheet 22 is laminated to the surface exposed on the front side). Is set larger than the distance) by a predetermined dimension, and a predetermined clearance is secured for each optical sheet 22 in the laminated state. In the state where the optical sheets 22 are stacked along the vertical direction, the optical sheet 22 (diffusion plate 22a) on the backmost side is in contact with the upper surface of the lower locking portion 26, whereas The optical sheet 22 (brightness enhancement sheet 22d) is arranged away from the lower surface of the upper locking portion 26.

  This embodiment has the structure as described above, and the operation thereof will be described subsequently. First, a method for manufacturing the optical sheet unit 20 will be briefly described. First, a holding member 23 is prepared in which a locking portion 26 is formed only on one end side of the shaft portion 25 and extends in a rod shape without forming the locking portion 26 on the other end side. Each optical sheet 22 is placed from the end side and inserted into each holding hole 24. After all the optical sheets 22 are stacked, the other end side of the shaft portion 25 is crushed by crushing or the like. An end-side locking portion 26 is formed to prevent the optical sheet 22 from coming off. As a result, as shown in FIGS. 2 and 3, the optical sheets 22 are held in a stacked state by the holding member 23.

  As described above, the optical sheet unit 20 obtained by unitizing the optical sheet 22 group in advance is carried into the manufacturing process of the liquid crystal display device 10 and is assembled. Thereby, compared with the case where the operation | work which laminates | stacks each optical sheet 22 in the manufacturing process of the liquid crystal display device 10 is performed, the order of lamination | stacking of the optical sheet 22 is mistaken, excess or deficiency arises in the optical sheet 22, or each optical sheet 22 is produced. It is possible to prevent foreign matters such as dust from being sandwiched therebetween. Then, the manufacturing process of the liquid crystal display device 10 is demonstrated.

  As shown in FIG. 4, after each linear light source 19 is accommodated in the case 18 of the backlight 12, an operation of attaching the optical sheet unit 20 to the opening of the case 18 is performed. Thereafter, the optical sheet unit 20 is held between the case 18 and the frame 21 by attaching the frame 21 onto the optical sheet unit 20. At this time, although the frame 21 is placed on the upper locking portion 26 of the holding member 23, it is kept in non-contact with the frontmost optical sheet 22 (luminance enhancement sheet 22d) (see FIG. 2). Thereafter, the liquid crystal panel 11 and the bezel 13 are sequentially assembled to assemble the liquid crystal display device 10 as shown in FIG.

  When the liquid crystal display device 10 described above is used, each linear light source 19 of the backlight 12 is turned on / off, and the temperature in the liquid crystal display device 10 fluctuates accordingly. On the other hand, since each optical sheet 22 may have different materials and thickness dimensions as described above, there may be a difference in the expansion / contraction rate due to the temperature change described above. If each optical sheet 22 is fixed with an adhesive or the like, the expansion allowance or contraction allowance of each optical sheet 22 is different, so there is a concern that the optical sheet 22 may be bent or wrinkled.

  However, in this embodiment, the shaft portion 25 of the holding member 23 is sized to have a sufficient clearance with respect to the holding hole 24, and the distance between the locking portions 26 is the total thickness dimension of each optical sheet 22. Therefore, each optical sheet 22 can be relatively displaced within the clearance range. Accordingly, each optical sheet 22 is allowed to expand (expand) / shrink along the surface direction in accordance with the temperature change, and thus it is possible to suppress or prevent the occurrence of bending or wrinkling in each optical sheet 22. .

<Embodiment 2>
A second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the holding member 30 is made of two parts and a positioning mechanism for the optical sheet unit 20A is provided. In the second embodiment, redundant description of the same structure, operation, and effects as those in the first embodiment will be omitted.

  As shown in FIG. 5, the holding member 30 has a two-part structure in which a first holding part 31 and a second holding part 32 are assembled. The first holding component 31 includes a first shaft portion 33 extending in the vertical direction (the thickness direction of each optical sheet 22, the direction intersecting (orthogonal to) the surface direction of each optical sheet 22), and the first shaft portion 33. Of these, it projects in the lateral direction (the surface direction of each optical sheet 22 and the direction intersecting (orthogonal to) the axial direction of each of the shaft portions 33 and 36) from the lower end side (the side opposite to the second locking portion 37 described below). The first locking portion 34 is configured. The 1st axial part 33 is formed in the substantially cylindrical shape, and the positioning hole 35 penetrated along an up-down direction is formed in the center part. The first locking portion 34 is configured to project radially outward from the outer peripheral edge of the lower end of the first shaft portion 33, and the diameter dimension thereof is set to be larger than the diameter dimension of the holding hole 24 of each optical sheet 22. . Further, as shown in FIG. 6, the holding member 30 is installed at both corners on the upper side of each optical sheet 22.

  The second holding part 32 includes a second shaft part 36 that can be fitted to the outside of the first shaft part 33 of the first holding part 31 and an upper end side of the second shaft part 36 (the first locking part described above). The second engaging portion 37 protrudes laterally from the opposite side of the portion 34. The second shaft portion 36 is formed in a substantially cylindrical shape along the outer peripheral surface of the first shaft portion 33, and the inner diameter dimension thereof is set to be substantially the same as the outer diameter dimension of the first shaft portion 33. The outer side of the first shaft portion 33 can be fitted with a press fit. The relationship between the outer diameter of the first shaft portion 33 and the inner diameter of the second shaft portion 36 can be changed in addition to the above. A fitting space 38 for receiving the first shaft portion 33 is formed in the center portion of the second shaft portion 36 so as to penetrate in the vertical direction.

  The outer diameter of the second shaft portion 36 is set to have a predetermined clearance with respect to the diameter of the holding hole 24 of each optical sheet 22. Similarly to the first locking portion 34, the second locking portion 37 is configured to protrude radially outward from the outer peripheral edge of the upper end of the second shaft portion 36, and the diameter dimension thereof is the diameter of each holding hole 24. It is set larger than the dimension.

  The lower end 36a of the second shaft part 36 of the second holding part 32 (the end opposite to the end where the second locking part 37 is provided) is attached to the first holding part 31 and 32. It abuts against the upper surface of the first locking portion 34 of the holding component 31 (the surface facing the second locking portion 37, the surface opposite to the locking surface with respect to the peripheral edge of the holding hole 24 of the optical sheet 22). . Thus, the vertical positional relationship between the holding parts 31 and 32 is determined, and the distance between the locking portions 34 and 37 is restricted to a predetermined size. The distance between the engaging portions 34 and 37 at this time is maintained at a size having a predetermined clearance with respect to the total thickness dimension of all the optical sheets 22.

  A first positioning projection 39 provided on the case 18A and a second positioning projection 40 provided on the frame 21A can be fitted into the positioning holes 35 of the first holding component 31. Both the first positioning protrusion 39 and the second positioning protrusion 40 are formed in a substantially cylindrical shape, and the outer diameter dimension thereof is set to be substantially the same as or smaller than the inner diameter dimension of the positioning hole 35. Thereby, the optical sheet unit 20 including the holding member 30, the case 18 </ b> A, and the frame 21 </ b> A can be positioned with respect to each other in the surface direction of the optical sheet 22. Note that the second positioning projection 40 of the frame 21A can be inserted into the fitting space 38 having a larger inner diameter than the positioning hole 35 in the second holding component 32.

  Then, the manufacturing method of the optical sheet unit 20 is demonstrated. First, as shown in FIG. 7, the holding holes 24 of the optical sheets 22 are sequentially passed from the upper side to the first shaft portion 33 of the first holding component 31 while being aligned. At this time, the hole edge lower surface of the holding hole 24 in the lowermost (back side) optical sheet 22 (diffusion plate 22 a) is locked to the upper surface of the first locking portion 34. As shown in FIG. 8, after the optical sheets 22 are stacked, the second shaft portion 36 of the second holding component 32 is inserted into the holding holes 24 from above. When the first shaft portion 33 is fitted into the fitting space 38 of the second shaft portion 36 (the second shaft portion 36 is fitted outside the first shaft portion 33) and reaches a predetermined depth, As shown in FIG. 9, the lower end portion 36 a of the second shaft portion 36 abuts against the upper surface of the first locking portion 34, so that further fitting is restricted. As a result, the distance between the locking portions 34 and 37 is maintained at a size having a predetermined clearance with respect to the total thickness dimension of all the optical sheets 22, and the second dimension with respect to the radial dimension of each holding hole 24. The expansion and contraction of each optical sheet 22 due to a temperature change is allowed in combination with the outer diameter of the shaft portion 36 having a predetermined clearance.

  Next, a process of assembling the optical sheet unit 20 manufactured as described above to the liquid crystal display device 10 will be described. When the optical sheet unit 20 is attached to the case 18A of the backlight 12, the first positioning protrusion 39 of the case 18A is inserted into the positioning hole 35 of the holding member 30, so that the optical sheet unit is inserted into the case 18A. 20 is aligned in the surface direction of the optical sheet 22. Thereafter, when the frame 21A is mounted on the optical sheet unit 20, the second positioning protrusion 40 of the frame 21A is inserted into the positioning hole 35 of the holding member 30, so that the frame 21A is inserted into the optical sheet unit 20. Is positioned in the surface direction of the optical sheet 22.

  The liquid crystal display device 10 assembled with the optical sheet unit 20 is used in a state where the orientation of each optical sheet unit 20 is aligned with the orientation shown in FIG. Therefore, when the liquid crystal display device 10 is actually used, the holding member 30 is suspended by the positioning protrusions, and the optical sheets 22 are supported by the holding member 30 in a suspended state. Thereby, the expansion and contraction of each optical sheet 22 can be allowed more reliably, and it is further useful for avoiding the occurrence of bending and wrinkles.

  As described above, according to the present embodiment, when the holding member 30 is made of two parts and the first holding part 31 and the second holding part 32 are assembled, the lower end part 36a of the second shaft part 36 is in the first relationship. Since the distance between the locking portions 34 and 37 is regulated by abutting against the locking portion 34, the holding member is assumed to be one component as in the first embodiment, and either of the locking portions is selected. Compared to the case where one of them is formed by tapping, the assembly with respect to the optical sheet 22 is facilitated, and the setting of the clearance in the axial direction of each of the shaft portions 33 and 36 can be made surely and easily.

  Moreover, the first holding component 31 in the holding member 30 is provided with a positioning hole 35 for the case 18A to which the optical sheet unit 20 is attached and the frame 21A, and the holding member 30 for holding each optical sheet 22 has a positioning function. It can be combined. Thereby, compared with the case where a positioning structure is provided separately from the holding member, the structure can be simplified.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In addition to the second embodiment described above, for example, as shown in FIG. 10, the first shaft portion 33 </ b> B of the first holding component 31 </ b> B is formed in a columnar shape and the positioning hole is omitted. .

  (2) The restriction means of the second embodiment described above can be changed. For example, as shown in FIG. 11, a restriction projection 41 is provided on the inner peripheral surface of the second shaft portion 36C of the second holding component 32C, and the first shaft portion of the first holding component 31C is provided with respect to the restriction projection 41. By abutting the upper end portion 33Ca of 33C (the end portion opposite to the first locking portion 34C), the positional relationship is determined in the vertical direction of both holding parts 31C, 32C, and between the locking portions 34C, 37C. The distance may be regulated.

  (3) In the second embodiment described above, the second positioning protrusion of the frame is sized to fit the fitting space of the second holding component, and the fitting space is used as a positioning hole for the second positioning protrusion of the frame. It doesn't matter.

  (4) In Embodiment 2 described above, the first holding component and the second holding component may be used upside down.

  (5) In the above-described first embodiment, the case where the holding holes and the holding members are installed at the four corner positions of each optical sheet is shown. However, the holding holes and the holding members are installed at any one of three corners of each optical sheet. May be. In Embodiment 2 described above, the case where a pair of holding holes and holding members are installed at the upper corners of each optical sheet has been shown, but one, three, or four of the four corners of each optical sheet are shown. You may install in. In addition, as long as it is an outer area (outer peripheral edge part) of the display area in each optical sheet, the holding holes and holding members may be installed at positions other than the corners, and the number of installations and installation positions at that time are arbitrarily set. Is possible.

  (6) The shaft portion (the first shaft portion and the second shaft portion), the holding hole, and the locking portion (the first locking portion and the second locking portion) may have a non-circular shape such as a square shape. .

  (7) The locking portion (the first locking portion and the second locking portion) does not need to have a structure that protrudes from the entire circumference of the outer peripheral edge of the shaft portion (the first shaft portion and the second shaft portion). You may be the form which protrudes from a part of outer periphery.

(8) A positioning protrusion may be provided from the holding member side, and a positioning hole or a positioning recess may be provided on the frame or the case side.
(9) The positioning member may be provided on the holding member of the form shown in the first embodiment.

Sectional drawing of the liquid crystal display device which concerns on Embodiment 1 of this invention. 1 is an enlarged view of the main part of FIG. Plan view of optical sheet unit Sectional drawing showing work to attach optical sheet unit to case Sectional drawing showing the holding structure of the optical sheet unit which concerns on Embodiment 2 of this invention Plan view of optical sheet unit Sectional drawing showing the operation | work which attaches a 1st holding component to each optical sheet Sectional drawing showing the operation | work which attaches a 2nd holding component with respect to each optical sheet to which the 1st holding component was attached Sectional drawing which shows the state which attached both holding parts to each optical sheet Sectional drawing of the holding structure of the optical sheet unit which concerns on other embodiment (1) of this invention Sectional drawing of the holding structure of the optical sheet unit which concerns on other embodiment (2) of this invention

Explanation of symbols

20 ... Optical sheet unit 18A ... Case (mounting member)
21A ... Frame (mounting member)
DESCRIPTION OF SYMBOLS 22 ... Optical sheet 23 ... Holding member 24 ... Holding hole 25 ... Shaft part 26 ... Locking part 30 ... Holding member 31 ... 1st holding part 32 ... 2nd holding part 33 ... 1st axial part (shaft part)
34 ... 1st latching | locking part (locking part, control means)
35 ... Positioning hole (positioning part)
36 ... Second shaft portion (shaft portion)
36a ... Lower end (regulating means)
37. Second locking part (locking part)

Claims (3)

It is intended to be held by a holding member in a state where a plurality of optical sheets having translucency are laminated,
Each optical sheet is provided with holding holes that can communicate with each other in a stacked state, whereas the holding member includes a shaft portion that is inserted into each holding hole, and axial directions from both end portions of the shaft portion. And a pair of locking portions that can be locked to the periphery of the holding hole,
The holding member has a total thickness of each optical sheet in which the diameter of the shaft portion has a clearance with respect to the diameter of each holding hole, and the distance between the both locking portions is stacked. An optical sheet unit formed so as to have a clearance with respect to dimensions. The holding member includes a first holding part and a second holding part that have the shaft part and the locking part and are assembled to each other. The first holding part and the second holding part include the shaft part. The optical sheet unit according to claim 1, further comprising a restricting unit capable of restricting a distance between the two engaging portions by abutting each other as they are assembled along the axial direction. The optical sheet unit according to claim 1, wherein the holding member is provided with a positioning portion for an attachment member to which the optical sheet unit is attached.

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