WO2009084379A1

WO2009084379A1 - Light source device and liquid crystal display device

Info

Publication number: WO2009084379A1
Application number: PCT/JP2008/072258
Authority: WO
Inventors: Masanori Mori; Mamoru Yabe
Original assignee: Omron Corporation
Priority date: 2007-12-28
Filing date: 2008-12-08
Publication date: 2009-07-09
Also published as: KR101121599B1; JP2009163952A; CN101779074B; JP5024038B2; CN101779074A; KR20100029140A

Abstract

Provided is a light source device (14) wherein a light guide plate (56), a light source (42) and at least one optical sheet (48) are stored in an optical element storing space (38) formed by a housing (26), and light inputted to the light guide plate (56) from the light source (42) is diffused in the light guide plate (56), and then planarly outputted from a light outputting surface (57) of the light guide plate (56). A liquid crystal display device (10) is also provided. The light source device or the like includes a wiring lead-out section (46) formed on the housing (26); a flexible printed board (24) introduced to the external from the optical element storing space (38) through the wiring lead-out section (46), by including an electric circuit connected to the light source (42); and a wiring protection section (60), which is integrally formed with the optical sheet (48) and is arranged between the housing (26) and the flexible printed board (24) at the wiring lead-out section (46). Thus, the circuit connecting section is not directly brought into contact with the housing and edges of the boards constituting the housing. Therefore, the flexible printed board is not broken while the light source device is being manufactured or used.

Description

Light source device and liquid crystal display device

The present invention relates to a light source device used as a backlight device disposed behind a liquid crystal panel, for example, and a liquid crystal display device in which the light source device and a liquid crystal panel are combined.

Patent Document 1 discloses a liquid crystal display device in which a liquid crystal panel and a light source device (backlight device) are combined. In this liquid crystal display device, the light source device includes a housing having a planar opening (planar light emitting unit) facing the liquid crystal panel. The housing accommodates a reflective sheet, a light guide plate, and a plurality of optical sheets in order from the opposite side (bottom plate side) of the planar opening. One side surface of the light guide plate (the end surface connecting the front surface and the back surface in contact with the reflection sheet and the optical sheet) is used as a light incident surface, and a plurality of light sources are arranged facing the light incident surface. The plurality of light sources are fixed to a flexible printed circuit board and are electrically connected to a circuit provided on the wiring board. The flexible printed circuit board is led out to the outside through a wiring lead-out part (opening part) formed on the side part of the housing.

The flexible printed circuit board is usually electrically connected to the power circuit of the circuit board mounted on the back surface (the surface opposite to the liquid crystal panel) of the housing. For this reason, the flexible printed circuit board led out from the side of the housing is usually bent once at a location protruding from the side of the housing, and then bent again at the corner that connects the side and back of the housing. Arranged along.

However, since the flexible printed circuit board has a structure in which a conductive foil (thickness: about 10-50 μm) is formed on a thin insulating film (thickness: about 10-50 μm), it is damaged by external force. Easy to do. Therefore, when the housing is configured by combining an upper housing part (chassis on the side of the liquid crystal panel) and a lower housing (chassis on the side opposite to the liquid crystal panel), the flexible print that protrudes from the housing when these two housing parts are combined. There is a problem that the substrate is damaged, and a problem that the insulating film of the flexible printed circuit board is damaged due to contact with the edge of the housing forming the wiring lead-out portion.

In order to solve this problem, Patent Document 2 discloses a technique for covering and protecting a flexible printed circuit board derived from a housing. However, since the technique of Patent Document 2 uses an independent protective member, there is a problem that the number of parts increases.

Japanese Patent No. 399358 JP 2001-331112 A

The present invention provides a technique for protecting a flexible printed circuit board that electrically connects a light source and a light source driving circuit in a light source device and a liquid crystal display device without increasing the number of components.

Specifically, in the light source device and the liquid crystal display device according to the present invention, a light guide plate, a light source, and at least one optical sheet are housed in an optical element housing space formed by a housing, and light incident on the light guide plate from the light source is received. In the light source device that diffuses in the light guide plate and then emits in a planar shape from the light exit surface of the light guide plate, the wire lead-out unit includes a wiring lead-out part formed in the housing and an electric circuit connected to the light source A flexible printed circuit board led out from the optical element housing space via the optical element and the optical sheet, and is interposed between the housing and the flexible printed circuit board in the wiring lead-out portion. A wiring protection part is provided.

According to the light source device and the liquid crystal display device of the present invention, since the circuit connection portion led out from the housing is covered with the optical sheet and protected, the flexible printed circuit board includes the housing and the circuit connection portion. There is no direct contact with the edge of the board. Therefore, the flexible printed circuit board is not damaged during manufacture or use of the light source device.

1 is a rear perspective view of a liquid crystal display device according to the present invention. The perspective view which looked at the light source device (except an upper housing) concerning the present invention from the back. The perspective view which looked at the light source device (except an upper housing) concerning the present invention from the upper part. The disassembled perspective view of the light source device (except an upper housing) which concerns on this invention. FIG. 4 is a development view of the optical sheet (reflective sheet) shown in FIGS. 2 and 3. The perspective view which shows the procedure which protects a wiring board using the wiring protection part formed in the reflective sheet of FIG. The perspective view which shows the procedure which protects a wiring board using the wiring protection part formed in the reflective sheet of FIG. The perspective view which shows the procedure which protects a wiring board using the wiring protection part formed in the reflective sheet of FIG. The perspective view which shows the procedure which protects a wiring board using the wiring protection part formed in the reflective sheet of FIG. The perspective view which shows the procedure which protects a wiring board using the wiring protection part formed in the reflective sheet of FIG. The perspective view which shows the other form of a wiring protection part. FIG. 8 is a development view of the wiring protection unit shown in FIG. 7. The perspective view which shows the other form of a wiring protection part. FIG. 10 is a development view of the wiring protection unit shown in FIG. 9. The perspective view which shows the other form of a wiring derivation | leading-out part. The perspective view which shows the other form of a wiring derivation | leading-out part with FIG. The perspective view which shows the other form of a wiring derivation | leading-out part with FIG.

Explanation of symbols

10: liquid crystal display device, 12: liquid crystal panel, 14: light source device (backlight device), 16: drive circuit, 18: printed wiring board, 20: electronic component, 22: flexible printed circuit board, 24: flexible printed circuit board, 26 : Housing, 28: Lower housing part, 30: Upper housing part, 32: Bottom plate, 34: Side plate, 36: Side plate, 38: Optical element accommodation space, 40: Light source unit, 42: Light source, 44: Circuit connection part, 46 : Wiring lead-out part, 48: reflection sheet, 50: bottom part, 52: side part, 54: opening, 56: light guide plate, 58: optical sheet, 60: wiring protection part, 62: first extension part, 64: first 2 extended portions, 66: first bent portion, 68: first covering portion, 70: second covering portion, 72: second bent portion, 74: side portion of light guide plate, 76: bottom edge Part, 78: third cover Portion, 80: slot, 82: first fold, 84: second fold, 86: fourth fold, 88: fourth cover, 90: fifth fold, 92: fifth Covering portion, 94: double-sided tape, 96: terminal, 98: terminal connecting portion, 100: wiring lead-out portion.

Hereinafter, embodiments of a light source device and a liquid crystal display device including the same according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a view of the liquid crystal display device as viewed from behind. The illustrated liquid crystal display device 10 includes a liquid crystal panel 12, a light source device (backlight device) 14 disposed behind the liquid crystal panel 12, and a drive circuit 16 disposed behind the light source device 14.

The drive circuit 16 has a printed wiring board 18. The printed wiring board 18 includes, for example, a plurality of driving electronic components 20 on a surface located on the opposite side of the light source device 14, and is connected to the liquid crystal panel 12 by a flexible printed circuit board 22 disposed beyond the side surface of the light source device 14. The light source device 14 is electrically connected and is electrically connected to the light source device 14 (a light source to be described later) by a flexible printed board 24 drawn to the back from one side of the back surface of the light source device 14.

The light source device 14 has a housing 26 that forms a rectangular space for accommodating a plurality of optical components described later. The housing 26 includes a housing part (lower housing part 28, which appears upward in FIG. 1) located on the drive circuit side, and a housing part (upper housing part 30, which appears on the lower side in FIG. 1). Have). 2 to 4 and particularly FIG. 4, the lower housing portion 28 has a rectangular bottom plate 32 and side plates 34 rising vertically from four sides thereof, and is formed, for example, by bending a single metal plate. Yes. The upper housing portion 30 includes a rectangular frame (not shown) that forms a planar light emitting portion (opening), and a frame side plate 36 (see FIG. 1) that rises vertically from the four sides of the frame. The lower housing portion 28 and the upper housing portion 30 are combined so that the frame side plate 36 of the upper housing portion 30 is positioned outside the side plate 34 of the lower housing 28, and the optical element accommodating space 38 is disposed inside the combined housing 26. (See FIG. 4) is formed.

As shown in FIG. 4, before combining the lower housing portion 28 and the upper housing portion 30, a plurality of optical elements are accommodated in the lower housing 28 (corresponding to the optical element accommodating space 38). Specifically, the light source unit 40 is disposed on the inner surface of one of the long side direction side plates 34 (34a). The light source unit 40 includes a strip-shaped flexible printed circuit board 24 having a lateral width that is equal to or slightly smaller than the height of the side plate 34a. An electric circuit (wiring) is integrally formed on the flexible printed circuit board 24. A plurality of light sources 42 are fixed to one side of one end of the flexible printed circuit board 24 at a predetermined interval, and they are electrically connected to a power supply circuit formed on the flexible printed circuit board 24. An LED is preferably used as the light source 42. The flexible printed circuit board 24 having such a configuration is fixed to the inner surface of the side plate 34a by appropriate fixing means (for example, double-sided tape) with the plurality of light sources 42 facing the inside of the accommodation space 38. As shown in FIG. 6A, the circuit connecting portion 44 on the other end side of the flexible printed circuit board 24 is an opening formed by cutting out a part of the side plate 34b in the short side direction adjacent to the side plate 34a. It is led out from the wiring lead-out part 46 of the part.

Next, a reflection sheet 48 that is one of optical sheets is accommodated in the accommodation space 38. The reflection sheet 48 has a bottom portion 50 that faces the bottom plate 32 and a side portion 52 that faces the four side plates 34. As shown in the drawing, the side portion 52 a facing the side plate 34 a to which the light source unit 40 is attached has an opening 54 formed by notching a portion corresponding to the light source 42, and the light source 42 is exposed from these openings 54. As will be described in detail later, the reflection sheet 48 is integrally formed with a wiring protection part 60 for protecting the circuit connection part 44 led out from the housing 26 of the flexible printed circuit board 24 described above.

A light guide plate 56 is accommodated inside the space surrounded by the reflection sheet 48. The light guide plate 56 is a substantially rectangular plate made of a translucent material having a thickness close to the height of the accommodation space 38 of the lower housing portion 28, and one longitudinal side surface (light incident surface) is opposed to the plurality of light sources 42. It is held in the state. One or a plurality of optical sheets 58 are placed on the light exit surface 57 of the light guide plate 56. The optical sheet 58 includes optical films such as a diffusion sheet and a prism sheet.

As described above, the upper housing portion 30 is disposed on the lower housing portion 28 in which the reflection sheet 48, the light guide plate 56, and the optical sheet 58 are accommodated. At this time, as shown in FIG. 1, the side plate 34 of the lower housing portion 28 is covered with the corresponding side plate 36 of the upper housing portion 30.

The wiring protection unit 60 will be described. As shown in FIG. 5, the wiring protector 60 is in the vicinity of the first extended portion 62 extending the long side end portion in the vicinity of the wiring lead-out portion 46 of the bottom portion 50 and the wiring lead-out portion 46 in the bottom portion 50. It has the 2nd expansion | extension part 64 which extended the short side edge part.

As shown in FIG. 6B, the first extension portion 62 is a connecting portion (first bent portion) between the first extension portion 62 and the bottom 50 when the reflection sheet 48 is attached to the lower housing portion 28. 66) and is disposed along the lower housing side plate 34a. As shown in the drawing, the first extending portion 62 extends from the vicinity of the light source 42 arranged at the right end portion of the drawing to the end portion of the side plate 34 (right end portion of the drawing), and a circuit existing behind the first extending portion 62. It is preferable to cover the connecting portion 44. In this state, the first extending portion 62 includes a first covering portion 68 that covers the inner surface of the side plate 34a and a second covering portion 70 that extends outward from the side plate 34a. 6C, after the light guide plate 56 is accommodated in the lower housing portion 28 as shown in FIG. 6C, the second covering portion 70 and the second covering portion 70 are connected to the second covering portion 70 as shown in FIG. It is bent at the second bent portion 72 between the covering portions 70, and the second covering portion 70 covers the light guide plate side surface portion 74 located at the wiring lead-out portion 46. The end portion of the second covering portion 70 extends downward in the drawing in a state where the second covering portion 70 is disposed on the side surface portion 74 of the light guide plate 56, and a part of the wiring lead-out portion 46 (the circuit later) It is preferable to include a third covering portion 78 that covers a bottom plate edge portion 76 (refer to FIG. 6A) forming a portion where the connecting portion 44 is disposed.

Returning to FIG. 5, as described above, the second extending portion 64 has the slot 80 formed at the location where the third covering portion 78 passes. Therefore, the third covering portion 78 can project downward in the figure through the slot 80 without interfering with the second extending portion 64 (see FIG. 6D). After the first extending portion 62 is arranged as described above, the circuit connecting portion 44 of the flexible printed circuit board 24 is bent at the first fold 82 corresponding to the second bent portion 72, and the second It arrange | positions along the coating | coated part 70. FIG. In addition, the circuit connecting portion 44 is folded along a second fold line 84 that crosses the circuit connecting portion 44 obliquely (with an angle of about 45 degrees) in the vicinity of the third covering portion 78, Along the portion 78, it is pulled out downward through the slot 80. Thereafter, the second extending portion 64 is bent at the connecting portion (the fourth bent portion 86 (see FIG. 6B)) between the second extending portion 64 and the bottom portion 50, and the second covering portion 70. Is overlaid on the circuit connection 44 located above (see FIG. 6E). In addition to the 4th coating | coated part 88 which covers the circuit connection part 44 on the 2nd coating | coated part 70, the 2nd expansion | extension part 64 is upward from the surface of the light-guide plate 56, as shown in FIG.6 (e). It has a fifth covering portion 92 that protrudes and is bent at the fifth bent portion 90 and disposed on the light guide plate 56. The fifth cover portion 92 is fixed to the light guide plate 56 by a double-sided tape 94 provided between the fifth cover portion 92 and the light guide plate 56 while being placed on the surface of the light guide plate 56. As shown in FIGS. 1 and 2, the circuit connection portion 44 protruding from the bottom plate of the lower housing 26 is disposed along the back surface of the lower housing 26, and a terminal 96 provided at an end portion of the circuit connection portion 44 is printed wiring. It is connected to a terminal connection part 98 provided on the plate 18.

As described above, according to the light source device 14 according to the embodiment, the flexible printed circuit board 24 supporting the plurality of light sources 42 is protected by the circuit connection portion 44 led out from the housing 26 being covered with the reflection sheet 48. ing. For this reason, the circuit connecting portion 44 does not directly touch the edge of the plate constituting the housing 26. Further, when the upper housing part 30 is mounted on the lower housing 26, the edge part of the upper housing part 30 does not directly contact the circuit connection part 44. Therefore, the flexible printed circuit board 24 is not damaged during the manufacture of the light source device 14. In addition, the target configuration can be obtained by simple modification by simply changing a part of the configuration of the conventional light source device. Further, the wiring protection unit 60 not only covers and protects the flexible printed circuit board 24 but also covers the side surface of the light guide plate 56 in the vicinity of the wiring lead-out unit 46, and therefore leaks from the side surface of the light guide plate 56. Since all the light is returned to the light guide plate 56, it is possible to obtain planar light emission with uniform brightness.

The wiring protection unit is not limited to the above-described form. For example, the wiring protection unit 100 in the form shown in FIGS. 7 and 8 is applied to a light source device in which the light source unit 40 is disposed along the bottom plate 32 of the lower housing unit 28. The wiring protection unit 100 includes an extension unit 104 provided integrally with the reflection sheet 48. The extending portion 104 includes a first covering portion 106 that extends from the bottom portion 48 toward the side plate 34 a and a second covering portion 108 that further extends the first covering portion 106. In actual application, as shown in FIG. 7, the first covering portion 106 protects the back surface (the surface facing the bottom plate 32) of the circuit connecting portion 44. The second covering portion 108 is bent at the bent portion 110 at the boundary with the first covering portion 106 to protect the surface of the circuit connecting portion 44 (the surface on the opposite side of the bottom plate 32). As shown in FIG. 7, the size of the first covering portion 106 and the second covering portion 108 protrudes through the wiring lead-out portion 46, and the circuit connection portion 44 is directly on the housing edge 112 of the wiring lead-out portion 46. It is preferable not to contact.

In the above description, the wiring protection portion is provided on the reflection sheet (optical sheet) 48, but may be provided on another optical sheet 58 disposed on the opposite side of the reflection sheet 48 with the light guide plate 56 interposed therebetween. When a plurality of optical sheets 58 are disposed, they may be provided on any of the plurality of optical sheets. Referring specifically to FIGS. 9 and 10, the wiring protector 120 is integrally formed on one optical sheet 58 that covers the surface of the light guide plate 56. The wiring protection unit 120 includes an extending portion 124 that protrudes from the edge of the region 122 that contacts the surface of the light guide plate 56 toward the side plate 34 a. The extension part 124 has three covering parts (a first covering part 126, a second covering part 128, and a third covering part 130) in order from the region 122 side. In actual application, before placing the optical sheet 58 on the light guide plate 56, the optical sheet 58 is bent by approximately 90 degrees at the bent portion 132 at the boundary between the first covering portion 126 and the second covering portion 128, and then The tube 136 is formed by folding at the bent portion 134 at the boundary between the second cover portion 128 and the third cover portion 130, and the circuit connection portion 46 is inserted into the tube 136. Thereafter, the region 122 of the optical sheet 58 is overlaid on the light guide plate 56. Also in this embodiment, the size of the wiring protection part 120 is determined so that the tube 136 formed by bending the wiring protection part 120 protrudes outside via the wiring lead-out part 46, as shown in FIG. It is preferable.

In the above description, the wiring lead-out part is formed by cutting off a part of the side plate 34 of the lower housing part 28, but the wiring lead-out part may be formed on the bottom plate 32 of the lower housing part 28. For example, as shown in FIG. 11 to FIG. 13, in this embodiment, the wiring lead-out portion (opening) 140 is formed in the vicinity of the connecting portion (corner portion) between the bottom plate 32 and the side plate 34 in the lower housing 28. The part 44 is drawn to the outside via the wiring lead-out part 140. Further, the wiring protection part 142 formed integrally with a part of the reflection sheet 48 (a part of the bottom part 50 or the side part 52) is pulled out via the wiring lead-out part 140, and the circuit connection part 44 is connected to the lower housing 28. The edge portion 144 is not directly contacted.

As is apparent from the above description, according to the light source device and the liquid crystal display device according to the present invention, the flexible printed circuit board is protected by the circuit connecting portion derived from the housing being covered with the optical sheet and protected. The connecting portion does not directly touch the edge of the housing and the plate constituting the housing. Therefore, the flexible printed circuit board is not damaged during manufacture or use of the light source device.

Claims

A light guide plate, a light source, and at least one optical sheet are housed in an optical element housing space formed by the housing, and light incident on the light guide plate from the light source is diffused in the light guide plate, and then the light exit surface of the light guide plate In the light source device emitting in a shape,
A wiring lead-out portion formed in the housing;
A flexible printed circuit board including an electric circuit connected to the light source and led out from the optical element housing space through the wiring lead-out part;
An optical apparatus, comprising: a wiring protection part formed integrally with the optical sheet and interposed between the housing and the flexible printed circuit board in the wiring lead-out part.
2. The optical circuit according to claim 1, wherein the wiring protection part is formed by folding a part of the optical sheet, and both surfaces of the flexible printed circuit board are protected by the folded wiring protection part. apparatus.
2. The optical apparatus according to claim 1, wherein the wiring protection part is disposed between a side surface adjacent to the light emitting surface of the light guide plate and the flexible printed circuit board disposed on the side surface.
The optical device according to claim 1, wherein the wiring protection unit is fixed to the light guide plate.
2. The optical device according to claim 1, wherein the optical sheet is a reflection sheet disposed between the rear surface of the light guide plate on the opposite side of the light emitting surface and the housing.
2. The optical apparatus according to claim 1, wherein the optical sheet is an optical film that covers the light emitting surface.
A liquid crystal display device comprising the light source device according to claim 1 and a liquid crystal panel disposed on the light emitting surface.