JP2012079418A - Light source device, liquid crystal display and flexible printed circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the size of a light source device and that of a liquid crystal display equipped with this from becoming larger in a direction parallel with a light-emitting direction of a light source, even if a protective element is mounted on a flexible printed circuit board for the light source.SOLUTION: The light source device 2 includes: the light source 19 to emit light from a light-emitting face 191; a light guide plate 17 having an incident face 175 opposing to the light-emitting face 191 of the light source 19 and an emitting face 172 to emit light made incident from the incident face 175; and the flexible printed circuit board having a light source arrangement part 181 on which the light source 19 is mounted, and an extended part 182 which is extended from the light source arrangement part 181 and arranged more separated from the light guide plate 17 than the light source arrangement part 181. The protective element 20 connected to the light source 19 is installed at the extended part 182, and the flexible printed circuit board 18 is bent so as to make a tip part of the extended part 182 closer to the light guide plate 17.

Description

  The present invention relates to a light source device, a liquid crystal display device, and a flexible printed board.

  Patent Document 1 describes a flexible printed board on which an LED and a protective element for protecting the LED are mounted. The flexible printed board includes an LED mounting portion, an extending portion, and a terminal portion. The LED is mounted on the LED mounting portion, and the protection element is mounted on the terminal portion.

JP 2007-293084 A

  However, the flexible printed circuit board is formed such that the extending portion and the terminal portion extend from the LED mounting portion in the direction opposite to the light emission direction of the LED. And the LED mounting part is attached with respect to a light guide plate so that LED may face the light guide plate side, and the flexible printed circuit board is provided in planar shape. Therefore, the size of the light source device in the direction parallel to the light emission direction of the LED is increased by the extended portion and the terminal portion of the flexible printed board. Similarly, the size of the liquid crystal display device provided with this light source device also increases.

  Therefore, the present invention prevents the size of the light source device and the liquid crystal display device including the light source device from increasing in the direction parallel to the light emission direction of the light source even when the protective element is mounted on the flexible printed circuit board for the light source. With the goal.

In order to solve the above problems, according to one aspect of the present invention,
A light source that emits light from the light exit surface;
A light guide plate having an incident surface facing the light exit surface of the light source, and an exit surface for emitting light incident from the incident surface;
A flexible printed circuit board comprising: a light source placement portion on which the light source is mounted; and an extension portion that extends from the light source placement portion and is disposed farther from the light guide plate than the light source placement portion; A light source device comprising:
A protection element connected to the light source is provided in the extending portion,
The light source apparatus is characterized in that the flexible printed circuit board is bent so that a tip end portion of the extending portion is brought close to the light guide plate.

In the light source device, preferably, the flexible printed circuit board is bent so that an angle formed by the extending portion and the light source arrangement portion is 90 degrees.
In the light source device, preferably, the flexible printed circuit board is bent along a linear folding line that partitions the light source arrangement portion and the extending portion.
In the light source device, preferably, a slit is provided on the folding line of the flexible printed circuit board.
In the light source device, preferably, a plurality of the light sources and the protection elements are provided,
When the flexible printed circuit board is projected along a light emission direction of the light source onto a surface parallel to the light emission surface of the plurality of light sources, the plurality of light sources and the plurality of protection elements do not overlap each other. Respectively.
Preferably, the light source device further includes a frame-shaped frame,
The light source, the flexible printed circuit board and the light guide plate are arranged inside the frame,
The extending portion of the flexible printed circuit board is disposed in contact with the inner wall of the frame;
Due to the elasticity of the flexible printed circuit board, the light source arrangement portion is urged in a direction approaching the light guide plate, and the light exit surface of the light source presses the incident surface of the light guide plate.
In the light source device, preferably, a first recess for accommodating the light source is formed on an end surface of the light guide plate.
In the light source device, it is preferable that a second recess for accommodating the protection element is formed on an end surface of the light guide plate.
In the light source device, preferably, the flexible printed circuit board extends from the light source disposition part, is disposed farther from the light guide plate than the light source disposition part, and is adjacent to the extension part. And a slit is provided between the extended portion and the wiring routing portion.

According to another aspect of the invention,
The light source device;
A liquid crystal display device comprising a liquid crystal display panel is provided.

According to still another aspect of the present invention,
A light source arrangement portion on which a light source is mounted;
Extending from the light source arrangement portion in the direction opposite to the light emission direction of the light source, and an extension portion on which a protection element is mounted,
A flexible printed circuit board is provided in which a slit is provided between the light source arrangement part and the extension part.

In the flexible printed circuit board, preferably, a linear fold line for partitioning the light source arrangement part and the extension part is provided,
The slit is provided along the fold line.
In the flexible printed circuit board, preferably, a wiring routing portion is provided extending from the light source arrangement portion in a direction opposite to the light emission direction of the light source, and adjacent to the extending portion, and the extending portion and A slit is provided between the wiring routing portion.

  According to the present invention, even when a protective element is mounted on a flexible printed circuit board for a light source, the size of the light source device and the liquid crystal display device including the same is prevented from increasing in a direction parallel to the light emission direction of the light source. be able to.

It is the disassembled perspective view which showed the whole structure of the liquid crystal display device concerning this embodiment. It is the schematic cross section which showed the partial cross section of the liquid crystal display device concerning this embodiment typically. It is the rear view which showed typically a part of flexible printed circuit board concerning this embodiment, and a light-guide plate. It is a rear view of the flexible printed circuit board which showed the state before attaching to a light source device.

  EMBODIMENT OF THE INVENTION Below, the form for implementing this invention is demonstrated using drawing. However, although various technically preferable limitations for implementing the present invention are given to the embodiments described below, the scope of the invention is not limited to the following embodiments and illustrated examples.

  FIG. 1 is an exploded perspective view of the liquid crystal display device 100, and FIG. 2 is a cross-sectional view taken along the line II-II in FIG. As shown in FIGS. 1 and 2, the liquid crystal display device 100 includes a liquid crystal display panel 1 and a light source device 2.

  The liquid crystal display panel 1 is of an active matrix type, and is configured such that a first transparent substrate 6 and a second transparent substrate 7 are arranged to face each other with a liquid crystal layer (not shown) interposed therebetween. First and second transparent electrodes (not shown) are provided on the inner surfaces of the first transparent substrate 6 and the second transparent substrate 7 facing each other. The first and second transparent electrodes form a plurality of pixels in a matrix form that control the transmission of light by changing the alignment state of the liquid crystal molecules in the liquid crystal layer by applying a voltage. As shown in FIG. 2, a polarizing plate 8 is attached to the rear surface of the first transparent substrate 6, and a polarizing plate 9 is attached to the front surface of the second transparent substrate 7. The first transparent substrate 6 is formed with an overhang portion 61 protruding from the second transparent substrate 7, and the display driving circuit 10 is mounted on the overhang portion 61. Further, the liquid crystal display panel flexible printed circuit board 11 for supplying a control signal from an LCD driver (not shown) to the display driving circuit 10 is connected to the overhanging portion 61.

  Next, the light source device 2 will be described with reference to FIGS. 3 is a rear view of the light source device 2 showing only a part of the flexible printed circuit board 18 and a part of the light guide plate 17, and FIG. 4 is a rear view of the flexible printed circuit board 18 showing a state before being attached to the light source device 2. The figure is shown. The light source device 2 is disposed to face the rear side of the liquid crystal display panel 1 and irradiates the rear surface of the liquid crystal display panel 1 with light. The light source device 2 includes a light guide plate 17, a flexible printed circuit board 18, a light source 19, a protection element 20, and the like arranged inside a frame 16 that is formed in a frame shape.

  The light guide plate 17 is a plate-like member formed in a substantially rectangular plate shape, and emits light taken from an incident surface 175 formed on one side from an emission surface 172 formed on the front surface. On the rear side of the light guide plate 17, a reflection sheet 15 that reflects light leaking from the rear surface of the light guide plate 17 toward the light guide plate 17 is provided. The rear surface of the light guide plate 17 and the reflection sheet 15 are bonded together via an adhesive layer (not shown).

As shown in FIG. 3, in the light source arrangement region 200 of the light guide plate 17, the plurality of first recesses 173 are recessed from the end surface 171 of the light guide plate 17 toward the normal direction of the end surface 171 and It is formed in a state penetrating in the thickness direction. The plurality of first recesses 173 are formed along the arrangement direction of the plurality of light sources 19 provided on the flexible printed circuit board 18, and the light sources 19 are accommodated in the first recesses 173. The incident surface 175 provided in the first recess 173 and the light exit surface 191 of the light source 19 face each other, and the pair of light source facing surfaces 176 provided in the first recess 173 and the light exit surface 191 of the light source 19 are orthogonal to each other. A pair of surfaces to be opposed to each other. The region between the adjacent first recesses 173 of the light guide plate 17 is bonded to the reflection sheet 15.
Further, in the light source arrangement region 200 of the light guide plate 17, the second recess 174 is recessed from the end surface 171 of the light guide plate 17 toward the normal direction of the end surface 171 in the region between the adjacent first recesses 173. It is formed in a state where it penetrates in the thickness direction of the light guide plate 17. A plurality of the second recesses 174 are formed along the arrangement direction of the plurality of protection elements 20 provided on the flexible printed circuit board 18, and the protection elements 20 are accommodated in the second recesses 174. And each of three side surfaces among the side surfaces of the protection element 20 and each of the three side surfaces of the 2nd recessed part 174 are facing. Here, the size of the second recess 174 is sufficiently small because the size of the protection element 20 is accommodated. Therefore, the area between the adjacent first recesses 173 of the light guide plate 17 has a sufficient contact area with the reflection sheet 15, and the light guide plate 17 and the reflection sheet 15 are securely bonded to each other.

  On the exit surface 172 of the light guide plate 17, a diffusion sheet 21, a first prism sheet 22, a second prism sheet 23, and a light shielding sheet 24 are laminated in order one by one. The diffusion sheet 21 diffuses light emitted from the emission surface 172 of the light guide plate 17 to make the luminance uniform. The first prism sheet 22 and the second prism sheet 23 refract the light diffused by the diffusion sheet 21 to increase the light intensity in the normal direction of the light guide plate 17. The light shielding sheet 24 is formed in a substantially square shape, and covers the front peripheral edge of the second prism sheet 23 and prevents light from leaking from the front peripheral edge of the second prism sheet 23. As shown in FIGS. 3 and 4, the four light sources 19 are attached to the flexible printed circuit board 18, and are respectively disposed in the first recesses 173 of the light guide plate 17. The light source 19 is disposed so that the light exit surface 191 of the light source 19 faces the incident surface 175. The light source 19 emits light in the normal direction from the light emission surface 191, and the emission direction is a light emission direction B. Further, the flexible printed circuit board 18 to which the light source 19 is attached is attached to one side of the light guide plate 17 on the incident surface 175 side.

As shown in FIG. 4, the flexible printed circuit board 18 includes a light source arrangement part 181 to which a light source 19 is attached, an extension part 182 extended from the light source arrangement part 181, and a wiring routing part 30. The flexible printed circuit board 18 is disposed such that the extending portion 182 and the wiring routing portion 30 are located farther from the light guide plate 17 than the light source placement portion 181 (see FIG. 2). Here, if a straight line passing between the light source arrangement portion 181, the extended portion 182, and the wiring routing portion 30 on the surface of the flexible printed circuit board 18 is a folding line A, the flexible printed circuit board 18 becomes the folding line A. It is bent along. That is, a fold line A is provided on the surface of the flexible printed circuit board 18 in the region between the protective element 20 and the light source 19 along the direction in which the protective element 20 is disposed or the direction in which the light source 19 is disposed. .
As a result, as shown in FIG. 2, the light source arrangement portion 181 is arranged along the exit surface 172 of the light guide plate 17, and the extending portion 182 is arranged along the entrance surface 175. The extending portion 182 extends from the first portion of the fold line A, and the wiring routing portion 30 extends from the second portion of the fold line A. The wiring routing portion 30 has a plurality of wirings connected at one end to the light source 19 and the protection element 20 and connected at the other end to a light source control driver (not shown) disposed outside the frame 16. Has been. In addition, a slit 40 is provided between the extended portion 182 and the wiring routing portion 30. With this slit 40, only the extending portion 182 is arranged along the incident surface 175, and the wiring routing portion is provided. 30 is arranged along the exit surface 172 of the light guide plate 17. The light source arrangement portion 181 is attached to one side portion of the exit surface 172 of the light guide plate 17 via the double-sided tape 25 on the incident surface 175 side. The extending portion 182 is provided so as to cover a part of the end surface 171 of the light guide plate 17. Further, the light source arrangement portion 181 and the extending portion 182 are arranged orthogonal to each other. That is, the flexible printed circuit board is bent so that the angle formed by the extending portion 182 and the light source arrangement portion 181 is 90 degrees. Since the flexible printed circuit board 18 is attached to the light source device 2 in a folded state as described above, the size of the flexible printed circuit board 18 can be suppressed small in a direction parallel to the light emission direction B. Miniaturization can be achieved. A plurality of slits 184 are formed on the folding line A of the flexible printed circuit board 18. That is, a slit 184 is formed on the surface of the flexible printed circuit board 18 in the region between the protective element 20 and the light source 19 along the direction in which the protective element 20 is disposed or the direction in which the light source 19 is disposed. The slit 184 is a substantially elliptical hole that penetrates the flexible printed circuit board 18 (see FIG. 4). Thereby, the flexible printed circuit board 18 is easily bent.

  Four protective elements 20 are attached to the extended portion 182 of the flexible printed circuit board 18 (see FIG. 4). The protection element 20 is connected to each light source 19 to prevent static electricity from flowing through the light source 19. The four protection elements 20 are attached on the same surface as the surface on which the four light sources 19 are attached on the flexible printed circuit board 18. The extended portion 182 is disposed so as to cover the end surface 171 of the light guide plate 17 by bending the flexible printed circuit board 18, and the protective element 20 is disposed in the second recess 174 formed in the end surface 171. . Thereby, the extending portion 182 can be disposed closer to the light guide plate 17, and the light source device 2 can be further reduced in size. Note that the protection element 20 and the second recess 174 do not need to be disposed extremely close to each other.

  Further, as shown in FIG. 2, the surface of the extending portion 182 opposite to the surface on which the protection element 20 is attached is in contact with the inner wall 161 of the frame 16. Thereby, the light source arrangement part 181 is biased in the direction approaching the light guide plate 17 by the elasticity of the flexible printed circuit board 18, and the light exit surface 191 of the light source 19 mounted on the light source arrangement part 181 is the incident surface of the light guide plate 17. 175 is pressed. When the light source 19 presses the light guide plate 17, no gap is generated between the light source 19 and the light guide plate 17, and deterioration of display quality can be prevented.

Here, the arrangement relationship between the light source 19 and the protection element 20 will be described.
The protection element 20 may be connected to any location on the flexible printed circuit board 18 as long as it is connected to the light source 19, but the folded flexible printed circuit board 18 is moved along the light emission direction B of the light source 19. It is desirable that the four light sources 19 and the four protection elements 20 are arranged so as not to overlap each other when projected onto a plane parallel to the light exit surface 191. With such an arrangement, the flexible printed circuit board 18 is bent without the protective element 20 coming into contact with the light source 19. Therefore, the bending line A of the flexible printed circuit board 18 can be set close to the light source arrangement part 181 side, and the light source device 2 can be further miniaturized in a direction parallel to the light emission direction B.
In contrast to this embodiment, for example, if the protective element 20 is provided in a region in front of the light source 19 in the light emission direction B, the protective element 20 interferes with the light source 19 emitting light, and the amount of light decreases. . For example, if the protective element 20 is provided immediately behind the light source 19 in the light emission direction B, the protective element 20 may come into contact with the light source 19 when the flexible printed board 18 is bent. Cannot be folded into. Furthermore, for example, if the protective element 20 is provided on the opposite surface of the flexible printed circuit board 18, the thickness of the light source device 2 to which the flexible printed circuit board 18 is attached increases.

  In addition, a slit 40 is provided between the extended portion 182 and the wiring routing portion 30 of the flexible printed circuit board 18 of the present embodiment. By providing the slit 40, the extending portion 182 can be bent without bending the wiring routing portion 30. Therefore, without applying excessive stress to the wiring routing portion 30, the wiring routing portion 30 can be easily pulled out from the inside to the outside of the frame 16 and connected to the light source control driver.

According to the above embodiment, since the flexible printed board 18 is attached to the light source device 2 in a bent state, the light source device 2 can be reduced in size in a direction parallel to the light emission direction B of the light source 19. Can do. Thereby, size reduction of the liquid crystal display device 100 provided with the light source device 2 can also be achieved.
Moreover, since the slit 184 is formed on the folding line A of the flexible printed circuit board 18, the flexible printed circuit board 18 is easily bent.
Further, when the flexible printed circuit board 18 attached to the light source device 2 is projected on a plane parallel to the light exit surface 191 of the light source 19 along the light exit direction B, the light source 19 and the protection element 20 do not overlap each other. By being arranged in this way, the flexible printed circuit board 18 is bent without contacting them. Therefore, the bending line A of the flexible printed circuit board 18 can be set on the light source arrangement portion 181 side, and the light source device 2 can be further reduced in size.
Further, due to the elasticity of the bent flexible printed circuit board 18, the light exit surface 191 of the light source 19 is disposed in contact with the incident surface 175 of the light guide plate 17, and a gap is formed between the light source 19 and the light guide plate 17. It is possible to effectively prevent the display quality from being degraded.

In addition, according to the said embodiment, although the flexible printed circuit board 18 was bent so that the light source arrangement | positioning part 181 and the extending part 182 might orthogonally cross, even if the flexible printed circuit board 18 is bent slightly. Good. Further, the flexible printed circuit board 18 may be bent so that the whole or a part of the extended portion 182 is bent, instead of being bent.
Moreover, the 1st recessed part 173 and the 2nd recessed part 174 which are formed in the end surface 171 of the light-guide plate 17 should just be formed in the position and magnitude | size which can arrange | position the light source 19 or the protection element 20 to the inner side, respectively. The shape does not have to be a substantially rectangular parallelepiped shape, and does not have to penetrate in the thickness direction of the light guide plate 17.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel 2 Light source device 16 Frame 17 Light guide plate 18 Flexible printed circuit board 19 Light source 20 Protection element 100 Liquid crystal display device 161 Inner wall 171 End surface 172 Injecting surface 173 First recessed part 174 Second recessed part 175 Incident surface 181 Light source arrangement part 182 Extension Installation portion 184 Slit 191 Light exit surface 200 Light source arrangement area A Bending line B Light exit direction

Claims (13)

A light source that emits light from the light exit surface;
A light guide plate having an incident surface facing the light exit surface of the light source, and an exit surface for emitting light incident from the incident surface;
A flexible printed circuit board comprising: a light source placement portion on which the light source is mounted; and an extension portion that extends from the light source placement portion and is disposed farther from the light guide plate than the light source placement portion; A light source device comprising:
A protection element connected to the light source is provided in the extending portion,
The light source device, wherein the flexible printed circuit board is bent so that a distal end portion of the extended portion is brought close to the light guide plate.   The light source device according to claim 1, wherein the flexible printed circuit board is bent so that an angle formed by the extending portion and the light source arrangement portion is 90 degrees.   The light source device according to claim 1, wherein the flexible printed circuit board is bent along a linear fold line that partitions the light source arrangement portion and the extending portion.   The light source device according to claim 3, wherein a slit is provided on the folding line of the flexible printed board. A plurality of the light sources and the protection elements are provided,
When the flexible printed circuit board is projected along a light emission direction of the light source onto a surface parallel to the light emission surface of the plurality of light sources, the plurality of light sources and the plurality of protection elements do not overlap each other. The light source device according to any one of claims 1 to 4, wherein the light source device is disposed in each. A frame-like frame;
The light source, the flexible printed circuit board and the light guide plate are arranged inside the frame,
The extending portion of the flexible printed circuit board is disposed in contact with the inner wall of the frame;
The light source placement portion is biased in a direction approaching the light guide plate by the elasticity of the flexible printed circuit board, and the light exit surface of the light source presses the incident surface of the light guide plate. The light source device according to any one of claims 1 to 5.   The light source device according to any one of claims 1 to 6, wherein a first recess in which the light source is accommodated is formed on an end surface of the light guide plate.   The light source device according to any one of claims 1 to 7, wherein a second concave portion in which the protection element is accommodated is formed on an end surface of the light guide plate.   The flexible printed circuit board further includes a wiring routing portion that extends from the light source placement portion, is disposed farther from the light guide plate than the light source placement portion, and is adjacent to the extension portion, and The light source device according to any one of claims 1 to 8, wherein a slit is provided between the installation portion and the wiring routing portion. The light source device according to any one of claims 1 to 9,
A liquid crystal display device comprising: a liquid crystal display panel. A light source arrangement portion on which a light source is mounted;
Extending from the light source arrangement portion in the direction opposite to the light emission direction of the light source, and an extension portion on which a protection element is mounted,
A flexible printed circuit board, wherein a slit is provided between the light source arrangement part and the extension part. A linear fold line is provided to partition the light source arrangement part and the extension part,
The flexible printed circuit board according to claim 11, wherein the slit is provided along the bend line.   A wiring routing portion extending from the light source arrangement portion in a direction opposite to the light emission direction of the light source and adjacent to the extending portion is provided, and a slit is provided between the extension portion and the wiring routing portion. The flexible printed circuit board according to claim 11, wherein the flexible printed circuit board is provided.

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