Patent Application
20150029436
The present invention relates to a display device with a flexible printed circuit board.
Recently, demand for flat panel displays (FPD) for liquid crystal display devices and the like, for example, has increased. A liquid crystal display device has a liquid crystal display panel in a rectangular plate shape and a backlight module as an illumination device disposed at the rear side of the liquid crystal display panel, for example (refer to Patent Document 1 and the like, for example).
The liquid crystal display panel has a rectangular plate shaped non-display area that is formed along the four peripheral sides of the panel. One side of the non-display area is a terminal region with a wide frame width. At the terminal region, a plurality of terminals are formed where one end portion of the flexible printed circuit board (FPC) is attached.
The backlight module has a rectangular plate shaped frame having a light guide plate and the like disposed on the inner side thereof. Furthermore, a liquid crystal display panel is attached and fixed to the frame of the backlight module with a double-sided tape.
In order to bond a wider area of the liquid crystal display panel and the frame, the double-sided tape is disposed on a relatively large area of the terminal region, and is provided so as to cover one whole side of the terminal region of the non-display area.
An FPC with an edge attached to the terminal region is bent at a side of the backlight module. Another end of the FPC is bonded to the rear surface of the backlight module with a double-sided tape and the like. When the FPC is bent in this manner, internal stress is generated in the region that is folded, and a restoring force is generated on the folded portion. Thus, there is a problem in which a portion of the liquid crystal display panel rises due to this restoring force of the FPC.
With a liquid crystal display device disclosed in Patent Document 1 an attempt is made to prevent the rising of the liquid crystal display panel by fixing the FPC to the frame using pins and adhesive materials. However, in the liquid crystal display device in Patent Document 1, due to one wide FPC being attached to the terminal region, the restoring force of the FPC becomes relatively large, making it difficult to prevent the rising of the liquid crystal display panel.
A known countermeasure is to divide the FPC into multiple FPCs and provide them on the terminal region. By providing a plurality of relatively narrow FPCs, it is possible to reduce the restoring force generated by each FPC. Furthermore, the manufacturing cost of the FPC can be reduced as the number of cuts of the FPC from the base material can be increased when manufacturing the FPC.
However, the liquid crystal display device of Patent Document 1 has a problem in which a plurality of pins and adhesive materials are needed to fix each FPC onto a frame, which significantly increases the number of components and thus requires additional effort in manufacturing.
Furthermore, when a plurality of regions of the display panel where a FPC is attached to rise due to the restoring force of each FPC, since the region in which the FPC is not attached is adhesively held by double-sided tape, the display panel deforms into a wave-shape at the terminal region where this FPC is provided, resulting in uneven display. Recently, the problem is more pronounced as display panels have lower rigidity due to becoming very thin.
The present invention was made in view of the above points, and aims at improving display quality while suppressing the increase in the number of components for a display device provided with a plurality of flexible printed circuit boards.
To achieve the above-mentioned aims, in the present invention, the display panel is bonded to the chassis (frame) in select areas, which correspond to where the respective flexible printed circuit boards and the display panel overlap in a plan view, and the surface of the display panel and the frame are not bonded in areas between the adjacent flexible printed circuit boards.
Specifically, the display device related to the first invention includes a frame; a display panel fixed to the frame; a plurality of flexible printed circuit boards that are arranged adjacent to each other, one end of each flexible printed circuit board being attached to the display panel, each flexible printed circuit board being bent and another end is bent towards a side of the frame opposite to the display panel; and an adhesive area provided in an area where the display panel overlaps the respective flexible printed circuit boards where the surface of the display panel is bonded to the frame, wherein a non-adhesive area is provided in an area between the plurality of the flexible printed circuit boards arranged adjacent to each other where the surface of the display panel is not bonded to the frame.
According to this invention, the restoring force of the bent flexible printed circuit board at the display panel causes stress in a direction that raises the frame in the adhesive areas. Meanwhile, in the non-adhesive area, the display panel and the frame are not bonded, and thus the concentration of stress near the border of the adhesive areas and non-adhesive area can be suppressed. Thus, in the display device provided with a plurality of flexible printed circuit boards, the display quality of the display device can be improved by ensuring that the display panel does not deform into a wave-shape, while suppressing an increase in the number of components used.
The second invention is the display device according to the first invention, further including: an adhesive member interposed between the frame and the display panel, the adhesive member having an adhesive portion on a surface of the adhesive member facing the display panel in the adhesive areas, and having a non-adhesive portion on a surface of the adhesive member facing the display panel in the non-adhesive area.
According to this invention, the adhesive member is provided in the adhesive area and the non-adhesive area, making it harder for foreign matter to penetrate between the display panel and the frame from outside, resulting in a more reliable display device. Furthermore, by providing one adhesive member for the plurality of select areas, the manufacturing procedure is simplified compared to providing individual adhesive members to each adhesive area.
The third invention is the display device according to the first invention, further including: a plurality of island-shaped adhesive members interposed between the frame and the display panel, the adhesive members being provided in island-shapes in the adhesive areas, each of the adhesive members having an adhesive portion formed on an entire surface of each adhesive member facing the display panel.
According to this invention, while the display panel and the frame are bonded in the adhesive areas by the adhesive member, since no adhesive member is provided in the non-adhesive area, the liquid crystal display panel and the frame are not bonded in the non-adhesive area.
In the fourth invention, the display device according to the third invention further includes: a shielding part that covers a gap between the adhesive members formed between the frame and the display panel.
According to this invention, because the gaps between the adhesive members adjacent to each other are covered by the shielding part, it is harder for foreign matter to enter between the display panel and the frame from outside, resulting in a more reliable display device.
The fifth invention is the fourth invention, wherein the shielding part is a spacer formed separately from the frame.
According to this invention the spacer can be formed of other suitable materials that are different from the materials used for the frame, the adhesive member, and the like.
The sixth invention is the display device according to the fourth invention, wherein the shielding part is formed of a portion of the frame.
According to this invention, since the shielding part can be made with the frame which is a material used to form the backlight module, the increase in the number of components from forming a shielding part can also be suppressed.
The seventh invention is the display device according to the first invention, wherein the frame includes protruding portions protruding towards the display panel in the adhesive areas, and a recessed portion formed between the protruding portions, and wherein the display device further comprises an adhesive member that covers the protruding portions and the recessed portion and that bonds the surface of the display panel to the frame at the protruding portions.
According to this invention, the bonding of the display panel in the adhesive area and the non-bonding of the liquid crystal display panel in the non-adhesive area can be achieved with ease while using one double-sided tape as the adhesive member.
In the eight invention, the display device according to any one of the first to seventh inventions, wherein a width of the adhesive area in an alignment direction of the plurality of the flexible printed circuit boards is narrower than a width of each of the flexible printed circuit boards in the alignment direction.
According to this invention, even if the frame and the display panel are slightly offset, the adhesive area can be formed on the area overlapping the flexible printed circuit board when bonding the display panel with the frame.
According to the present invention, the concentration of stress near the boundary between an adhesive area and a non-adhesive area of a display panel can be suppressed because a surface of the display device and a frame is bonded in an area that overlaps a flexible printed circuit board while a surface of the display device and a frame is not bonded in a region between flexible printed circuit boards arranged adjacent to each other. Thus, in the display device provided with a plurality of flexible printed circuit boards, the display quality of the display device can be improved by ensuring that the display panel does not deform into a wave-shape, while suppressing the increase in the number of components used.
Embodiments of the present invention will be described in detail below with reference to drawings. In the present embodiment, a liquid crystal display device will be described as an example of a display device of the present invention. The present invention is not limited to the embodiments below.
As shown in
As shown in
The frame 11 is provided with a first step surface 17 formed in the inner side of an outer edge part 16, the first step surface 17 being lower than the outer edge part 16. In the inner side of the first step surface 17, a second step surface 18 is formed even lower than the first step surface 17. In the frame 11, a step surface higher than the first step surface 17 may be formed between the inner side of the outer edge part 16 and the outer side of the first step surface 17, for example.
The second step surface 18 is provided with the reflective sheet 14 and an LED substrate 19. The LED substrate 19 is formed of a flexible substrate. A light guide plate 13 is disposed on the reflective sheet 14. A plurality of the LEDs 12 that are arranged on the LED substrate 19 are disposed on a side face of the light guide plate 13. The optical sheet 15 such as a lens sheet is provided on the light guide plate 13.
A light from the LED 12 entering a side face of the light guide plate 13 is reflected and diffused inside the plate. The light outputted from the light guide plate 13 towards the reflective sheet 14 is reflected by the reflective sheet 14 and is again received by the light guide plate 13. The light outputted from the upper face of the light guide plate 13 passes through the optical sheet 15 and is outputted as an illumination light. In this manner, the backlight module 10 supplies illumination light to the liquid crystal display panel 20.
The liquid crystal display panel 20 is formed in a rectangular plate shape and is fixed to the frame 11 of the backlight module 10. As shown in
A transparent common electrode (not shown), a color filter (not shown) and the like are formed on the opposite substrate 22. A plurality of pixel electrodes (not shown) arranged in a matrix and a plurality of TFTs (thin-film transistors) connected to the pixel electrodes are formed on the TFT substrate 21. Polarizing plates 29 are attached to the TFT substrate 21 on the surface opposite to the surface facing the opposite substrate 22 and the opposite substrate 22 on the surface opposite to the surface facing the TFT substrate 21, respectively.
A liquid crystal layer (not shown) is sealed between the TFT substrate 21 and the opposite substrate 22. Furthermore, as shown in
Furthermore, in the non-display area 24 of the TFT substrate 21, a terminal region 25 with a plurality of terminals formed therein is provided as an area that is not facing the opposite substrate 22. The terminal region 25 is formed along one side of the liquid crystal display panel 20, and the width of the terminal region in the direction orthogonal to the side is wider than the non-display area 24 formed along other sides.
A plurality of flexible printed circuit boards (hereinafter, FPCs) are provided in the liquid crystal display panel 20, and are arranged adjacent to each other at prescribed intervals. As shown in
Also, as shown in
Also, the liquid crystal display device 1 as shown in
As shown in
In the present embodiment, a non-adhesive part 34 is formed by exposing the base material 31 by not providing the second adhesive part 33 in the non-adhesive area 42. In other words, the non-adhesive part 34 is provided between the second adhesive parts 33 arranged adjacent to each other.
The double-sided adhesive tape 35 extends along a side of the liquid crystal display panel 20 in a belt-shape in which the aforementioned double-sided adhesive tape 35 is provided, and has a film-shaped base material 36 and adhesive layers 37 provided on an entire surface of the top face and the bottom face of the base material 36.
Base materials 31 and 36 are formed of plastic films and the like, for example, and the first adhesive part 32, the second adhesive part 33, and the adhesive layer 37 are formed of acrylic-based adhesives and silicone-based adhesives, for example.
The second adhesive part 33 and the non-adhesive part 34 of the adhesive member 30 can be formed by coating the base material 31 with adhesives through a mask with an opening arranged in the area to become the adhesive area 41.
An upward (in other words, the direction in which the liquid crystal display panel 20 rises from the frame 11) stress A in
By contrast, according to Embodiment 1, since the surface of the liquid crystal display panel 20 and the frame 11 are bonded in the adhesive area 41 that overlaps with the FPCs 40, and the surface of the liquid crystal display panel 20 and the frame 11 are not bonded in the non-adhesive area 42 between the FPCs 40 adjacent to each other, while both the upward stress A and the downward stress B in
Moreover, because the adhesive member 30 is provided across the adhesive area 41 and the non-adhesive area 42, foreign matter is prevented from entering the area between the liquid crystal display panel 20 and the frame 11, resulting in a more reliable liquid crystal display device 1. Furthermore, by providing one adhesive member 30 for the plurality of adhesive areas 41, the manufacturing procedure is simplified compared to a case in which individual adhesive members 30 are provided in each adhesive area 41.
Furthermore, when bonding the liquid crystal display panel 20 to the frame 11, even if the frame 11 and the liquid crystal display panel 20 are slightly offset, the adhesive area 41 can be formed in the area overlapping the FPC 40.
The liquid crystal display device 1 of the above-mentioned Embodiment 1 has one adhesive member 30, but the liquid crystal display device 1 of the Embodiment 2 is different in that it has a plurality of adhesive members 30, and none of the adhesive members 30 have a non-adhesive part 34.
As shown in
Furthermore, in the liquid crystal display device 1, a shielding part 45 that covers the gaps between the adhesive members 30 is formed between the frame 11 and the liquid crystal display panel 20. In other words, the shielding parts 45 are provided in the respective non-adhesive areas 42.
In Embodiment 2, the shielding part 45 is formed of a portion of the frame 11. In other words, as shown in
Furthermore, each recess portion 46 houses the aforementioned adhesive member 30. Furthermore, while the first adhesive part 32 of the adhesive member 30 is bonded to the frame 11 at the bottom face of the recess portion 46, the second adhesive part 33 of the adhesive member 30 is bonded to the bottom of the liquid crystal display panel 20.
Therefore, in Embodiment 2 also, while the liquid crystal display panel 20 and the frame 11 are bonded in the adhesive area 41 by the adhesive member 30, because no adhesive member 30 is provided in the non-adhesive area 42, the liquid crystal display panel 20 and the frame 11 are not necessarily bonded to each other. Thus, the concentration of stress near the boundary between the adhesive area 41 and the non-adhesive area 42 of the liquid crystal display panel 20 can be suppressed, and the display quality of the liquid crystal display device 1 can be improved by ensuring that the liquid crystal display panel 20 does not deform into a wave-shape.
Furthermore, since the gaps between the adhesive members 30 adjacent to each other are covered by the shielding part 45, it is harder for foreign matter to enter between the liquid crystal display device 20 and the frame 11 from outside, resulting in a more reliable liquid crystal display device 1. Moreover, since the shielding part 45 can be made of the frame 11, which is a material used to form the backlight module 10, the increase in the number of components from forming a shielding part 45 can also be suppressed.
The liquid crystal display device 1 of the above mentioned Embodiment 1 has one adhesive member 30, but the liquid crystal display device 1 of the present Embodiment 2 is different in that it does not have a plurality of adhesive members 30. Furthermore, while the shielding part 45 is formed of a portion of the frame 11 in the Embodiment 2, the present Embodiment 3 is different in that the shielding part 45 is formed of another member.
As shown in
A shielding part 45 is provided on the liquid crystal display device 1 that covers the gaps between the adhesive members 30 formed between the frame 11 and the liquid crystal display panel 20. In other words, the shielding parts 45 are provided in each non-adhesive area 42 respectively.
The shielding part 45 of Embodiment 3 is formed of a spacer 45 that is formed independently of the frame 11. For example, the spacer 45 can be formed of a sponge, a rubber material, and the like. Furthermore, the spacer 45 is provided with a plurality of openings 48 formed in the adhesive area 41 and also provided on a first step surface 17 of the frame 11. Also, a surface of the spacer 45 is in contact with the bottom face of the liquid crystal display panel 20.
Each opening 48 is provided with an adhesive member 30. In this manner, while the adhesive members 30 are disposed in the adhesive areas 41, the non-adhesive area 42 is provided with a shielding part 45 formed of a spacer 45. In each adhesive area 41, while the first adhesive part 32 of the adhesive member 30 is attached to the frame 11, the second adhesive part 33 of the adhesive member 30 is attached to the bottom face of the liquid crystal display panel 20.
Therefore, also for this Embodiment 3, while the liquid crystal display panel 20 and the frame 11 are bonded in the adhesive area 41 by the adhesive member 30, since no adhesive member 30 is provided in the non-adhesive area 42, the liquid crystal display panel 20 and the frame 11 are not necessarily bonded. Thus, the concentration of stress near the boundary between the adhesive area 41 and the non-adhesive area 42 of the liquid crystal display panel 20 can be suppressed, and the display quality of the liquid crystal display device 1 can be improved such that the liquid crystal display panel 20 is not deformed into a wave-shape.
Furthermore, because the gaps between the adhesive members 30 adjacent to each other are covered by the shielding part 45, it is more difficult for foreign matter to enter an area between the liquid crystal display panel 20 and the frame 11, which results in a more reliable liquid crystal display device 1. Furthermore, because the shielding part 45 is formed of the spacer 45 that is formed separately from the frame 11, the spacer 45 can be formed of other suitable materials (such as sponge and rubber, for example) that are different from the materials used for the frame 11, the adhesive member 30, and the like.
While an adhesive member 30 that has a second adhesive part 33 and a non-adhesive part 34 was provided on a flat first step surface 17 of a frame 11 in Embodiment 1, Embodiment 4 is provided with adhesive members 30 that do not have a non-adhesive part 34 on the recessed and protruding portions of a frame 11.
As shown in
Furthermore, an adhesive member 30 that covers the protruding portions 51 and the recessed portion 52 of the frame 11 and bonds a surface of the liquid crystal display panel 20 to the frame 11 at the protruding portions 51 is provided between the liquid crystal display panel 20 and the frame 11. The adhesive member 30 is formed of a double-sided tape and includes: a film-shaped base material 31, a first adhesive part 32 provided on an entire surface of a base material 31 opposite to the liquid crystal display panel 20, and a second adhesive part 33 provided on an entire surface of the base material 31 facing the liquid crystal display panel 20.
In an adhesive area 41, while the first adhesive part 32 of the adhesive member 30 is attached to the frame 11, the second adhesive part 33 is attached to the bottom face of the liquid crystal display panel 20. Meanwhile, in the non-adhesive area 42, the first and second adhesive parts 32 and 33 are not bonded to the frame 11 and the liquid crystal display panel 20, respectively.
Also, in the non-adhesive area 42, only one of the first and second adhesive parts 32 and 33 may be bonded to the frame 11 or the liquid crystal display panel 20.
Therefore, in Embodiment 4 also, the liquid crystal display panel 20 and the frame 11 can be bonded by the adhesive member 30 in the adhesive area 41, while the liquid crystal display panel 20 and the frame 11 are not bonded in the non-adhesive area 42. Thus, the concentration of stress near the boundary between the adhesive area 41 and the non-adhesive area 42 of the liquid crystal display panel 20 can be suppressed, and the display quality of the liquid crystal display device 1 can be improved by ensuring that the liquid crystal display panel 20 does not deform into a wave-shape.
Moreover, the bonding of the liquid crystal display panel 20 in the adhesive area 41 and the non-bonding of the liquid crystal display panel 20 in the non-adhesive area 42 can be achieved with ease while using one double-sided tape as the adhesive member 30.
Embodiment 5 does not have a shielding part 45 unlike Embodiments 2 and 3, which were provided with a shielding part 45 in the non-adhesive area 42.
Therefore, as shown in
Meanwhile, a gap is provided between the first step surface 17 of the frame 11 and a bottom face of the liquid crystal display panel 20 in the non-adhesive area 42. Due to this, the liquid crystal display panel 20 is not bonded to the frame 11 in the non-adhesive area 42.
Therefore, in Embodiment 5 also, the liquid crystal display panel 20 and the frame 11 can be bonded by the adhesive member 30 in the adhesive area 41, while the liquid crystal display panel 20 and the frame 11 are not bonded in the non-adhesive area 42, and thus the concentration of stress near the boundary between the adhesive area 41 and the non-adhesive area 42 of the liquid crystal display panel 20 can be suppressed. Therefore, the display quality of the liquid crystal display device 1 can be improved while ensuring that the liquid crystal display panel 20 does not deform into a wave-shape.
In addition, a shielding part 45 is not provided, which simplifies the structure of the device and reduces the manufacturing cost.
In the above-mentioned embodiments, examples of providing an adhesive area 41 for all areas that overlap with a plurality of FPCs 40 were mentioned, but the present invention is not limited to these examples; as shown in
Furthermore, for each of the embodiments above, it has been explained that an adhesive area 41 is provided in an area that overlaps the FPC 40, but the present invention may also be provided with a plurality of adhesive areas 41 in the area that overlaps the FPC 40 as shown in
Furthermore, explanations of an example in which the width of an adhesive area 41 is narrower than the width of the FPC 40 were given for the respective embodiments above, but the present invention may also have an adhesive area 41 that protrudes beyond the edge of the FPC 40 as shown in
Furthermore, an explanation of an example of a liquid crystal display device 1 as a display device related to the present invention was provided for the respective embodiments above, but the present invention may also be applied to other display devices such as organic EL display devices and plasma display devices in the same manner.
For example, the present invention can also be used for an organic EL display panel with a plurality of FPCs attached, and also for an organic EL display device with a frame that is fixed to the organic EL display panel.
As explained above, the present invention is useful for a display device that has a flexible printed circuit board.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-024043 | Feb 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/000545 | 1/31/2013 | WO | 00 |
