JP3792574B2 - Backlight structure of liquid crystal display device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a backlight structure of a liquid crystal display device, and more particularly to a structure for mounting a light emitting element on a flexible wiring board (hereinafter abbreviated as “FPC”) and positioning the FPC.
[0002]
[Prior art]
Conventionally, in order to uniformly illuminate the liquid crystal display panel, a light guide plate has been disposed below the liquid crystal display panel. This light guide plate has a function of uniformly guiding light from light emitting elements such as LEDs to the entire liquid crystal display panel. The light emitting element is positioned with respect to such a light guide plate so that the positional relationship with the light guide plate is predetermined in order to guide light accurately and efficiently toward the liquid crystal display panel. 4 to 6 show an example of a structure for positioning the issuing element with respect to the light guide plate. In the positioning structure shown here, a light emitting element is mounted on an FPC for thinning, and the light emitting element is arranged at an optimum position such as a side of the light guide plate.
[0003]
As shown in FIG. 4, the liquid crystal display panel 4 is disposed in the upper part and the light guide plate 6 is disposed in the lower part in the frame 2. A diffusion plate 8 is provided between the liquid crystal display panel 4 and the light guide plate 6. The light emitting element 12 is mounted on the FPC 10 for electrical connection to the liquid crystal display panel 4 and is disposed on the side of the light guide plate 6.
[0004]
As shown in FIGS. 4 and 5, the light emitting element 12 is positioned by providing a guide hole 10a in the FPC 10 and passing the guide pin 2a protruding from the bottom inner surface of the frame 2 through the guide hole 10a. It stopped and positioned.
[0005]
[Problems to be solved by the invention]
In the above prior art, the solder 14 is used as means for attaching the light emitting element 12 to the FPC 10. When the light emitting element 12 is soldered to the FPC 10 in this way, the light emitting element 12 may float and move on the solder 14, and the longitudinal direction of the light emitting element 12 with respect to the longitudinal axis 16 of the FPC 10 as shown in FIG. The direction of the direction axis 18 may not match. When such misalignment of the light emitting element 12 occurs, it is assumed that the guide hole 10a provided in the FPC 10 is positioned on the axis 16 of the FPC 10 and that the guide pin 2a is also not misaligned in the light emitting element 12. Therefore, the positional deviation of the light emitting element 12 becomes the positional deviation of the light emitting element 12 with respect to the light guiding plate 6 as it is. When the position of the light emitting element 12 with respect to the light guide plate 6 is shifted in this way, the light irradiation angle from the light emitting element 12 to the light guide plate 6 becomes narrower or tilted, so that the light guide plate 6 illuminates the liquid crystal display panel 4. And chromaticity varies. Therefore, it has been a problem to provide a more stable backlight structure without such variations in luminance and chromaticity.
[0006]
Further, the positional deviation of the light emitting element 12 as described above also occurs when the FPC 10 is hooked on the guide pin 2 a of the frame body 2. That is, since the FPC 10 is thin and flexible, it has low rigidity and may be deformed even with a slight force. For this reason, when the guide pin 2a of the frame body 2 is passed through the guide hole 10a, as shown in FIG. 6, if an external force is applied or is not properly latched, the peripheral portion 10b of the guide hole 10a is The FPC 10 may be hooked on the guide pin 2a in a deformed state. In this case, even if the light emitting element 12 is properly attached to the FPC 10, the position of the FPC 10 with respect to the light guide plate 6 is misaligned. As a result, the light emitting element 12 is misaligned with respect to the light guide plate 6. turn into. Therefore, also in this case, variations in luminance and chromaticity occurred.
[0007]
The present invention has been made in view of the above-described problems of the prior art. By always keeping the position of the light emitting element with respect to the light guide plate at an appropriate position, variations in luminance and chromaticity are eliminated, lighting performance is stabilized, and manufacturing costs are further reduced. The present invention provides a backlight structure of a liquid crystal display device that reduces the amount of light.
[0008]
[Means for Solving the Problems]
According to the backlight structure of the liquid crystal display device of the present invention, as shown in claim 1, a liquid crystal display panel and a light guide plate are arranged in a frame, and a flexible wiring board on which a light emitting element is mounted is provided in the frame. In the liquid crystal display device that is positioned so as to irradiate light to the light guide plate by being hooked on the guide pin, the flexible wiring board is provided with a first guide hole having an inner diameter that loosely fits the guide pin, and the guide A guide plate having a second guide hole adapted to the pin is attached to the flexible wiring board in correspondence with the position of the light emitting element, and the second guide hole located in the first guide hole is attached to the guide pin. The light-emitting element is positioned by being fitted to. The first guide hole in the backlight structure of the liquid crystal display device is disposed on an axis of the flexible wiring board, and the guide plate extends on an extension of the axis of the light emitting element. The second guide hole is positioned and attached to the flexible wiring board. Further, according to a third aspect of the present invention, a pair of the first guide holes in the backlight structure of the liquid crystal display device are provided across the light emitting element, and the second guide holes of the guide plate are the first guide holes. It is provided so that it may each be located in the guide hole. In addition, the guide plate in the backlight structure of the liquid crystal display device is bonded to the flexible wiring board with an adhesive tape or an adhesive as shown in claim 4.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
In the backlight structure of the liquid crystal display device of the present invention, the guide plate having the second guide hole that fits the guide pin of the frame is attached to the FPC having the first guide hole. The guide plate is attached to the FPC so as to correspond to the position of the light emitting element. That is, the guide plate is positioned so that the second guide hole of the guide plate is located in the first guide hole of the FPC and is located on the extension of the axis of the light emitting element. Therefore, when the FPC is hooked by passing the guide pin of the frame body through the second guide hole of the guide plate, the FPC is inclined with respect to the light guide plate, but the light emitting element is inclined with respect to the light guide plate. It is positioned in a proper state without any problems.
[0010]
Further, since the guide plate does not need to have flexibility like FPC, the rigidity can be increased. By setting the rigidity of the guide plate to be high in this way, the second guide hole fitted to the guide pin is not deformed, and the position of the light emitting element is fixed when the FPC is hooked on the guide pin of the frame. Misalignment can also be prevented.
[0011]
【Example】
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view showing a main part of a backlight structure of a liquid crystal display device according to an embodiment of the present invention, FIG. 2 is a plan view of the light emitting element shown in FIG. 1, and FIG. It is a principal part cross-sectional view which shows FPC etc. FIG.
[0012]
Reference numeral 22 denotes a frame, which opens upward, and a pair of guide pins 22a are provided at predetermined positions on the inner surface of the bottom 22b. A liquid crystal display panel 24 is accommodated in the upper opening of the frame 22. A light guide plate 26 is housed below the frame 22 so as to be positioned below the liquid crystal display panel 24. Further, a diffusion plate 28 is provided between the light guide plate 26 and the liquid crystal display panel 24 so as to overlap the light guide plate 26.
[0013]
Reference numeral 30 denotes an FPC connected to the liquid crystal display panel 24 for electrically connecting to the liquid crystal display panel 24. The FPC 30 shown in the figure is branched from the main body for illumination, and is drawn out so that a light emitting element to be described later can be arranged at an optimum position. The FPC 30 is provided with a pair of first guide holes 30a with a light emitting element to be described later interposed therebetween. The first guide hole 30 a is disposed so that the center thereof is located on the longitudinal axis 36 of the FPC 30. The inner diameter of the first guide hole 30a is set to be considerably larger than the outer diameter of the guide pin 22a, and is set to a size that allows the guide pin 22a to be loosely fitted.
[0014]
A light emitting element 32 such as an LED is mounted between the first guide holes 30 a of the FPC 30 with solder 34.
[0015]
Reference numeral 40 denotes a guide plate, and in this embodiment, the guide plate is set to have a rectangular shape whose outer dimension is larger than that of the first guide hole 30a of the FPC 30. A second guide hole 40a having an inner diameter suitable for the guide pin 22a is provided at the approximate center of the guide plate 40. The guide plate 40 is attached to the FPC 30 such that the second guide hole 40 a is positioned in the first guide hole 30 a of the FPC 30 and is positioned on the extension of the axis 38 of the light emitting element 32. Yes. Further, the guide plate 40 is formed of a plate material having higher rigidity than the FPC 30, and is adhered to the FPC 30 with an adhesive tape such as a double-sided tape or an adhesive.
[0016]
In the backlight structure having the above-described configuration, the FPC 30 is attached to the frame body 22 by engaging the guide pins 22a of the frame body 22 in the second guide holes 40a of the guide plate 40. As a result, as shown in FIG. 2, the second guide hole 40 a of the guide plate 40 corresponds to the light emitting element 32 even if the axis 38 of the light emitting element 32 does not coincide with the axis 36 of the FPC 30 and misalignment occurs. Thus, the light emitting element 32 is positioned so as to face the light guide plate 26 in an appropriate state by fitting the guide pin 22a into the second guide hole 40a. can do.
[0017]
Further, the FPC 30 is hooked by fitting the second guide hole 40a of the guide plate 40 and the guide pin 22a of the frame 22, and only the peripheral edge of the first guide hole 30a of the FPC 30 is directly guided by the guide pin 22a. Never touch. Thus, the FPC 30 is attached to the frame body 22 through the highly rigid guide plate 40, and the second guide hole 40 a is not deformed and the light emitting element 32 is not displaced.
[0018]
In the present embodiment, the guide plate 40 is attached to the FPC 30 so as to correspond to the first guide hole 30a of the FPC 30, but a single guide plate 40 having two second guide holes 40a is formed. It can be modified to be attached to the FPC 30.
[0019]
【The invention's effect】
According to the present invention, even if a positional deviation occurs when the light emitting element is attached to the FPC, the positional deviation of the light emitting element can be corrected by attaching the guide plate to the FPC so as to correspond to the light emitting element. Thereby, the variation in the brightness | luminance and chromaticity which illuminate a liquid crystal display panel from a light emitting element through a light-guide plate for every product can be eliminated, and illumination performance can be stabilized.
[0020]
Further, by attaching the guide plate to the FPC, the guide plate can be fitted to the guide pin of the frame body through the guide plate having high rigidity, and the positional deviation of the light emitting element can be prevented when attaching to the frame body. it can.
[0021]
In addition, since it is possible to prevent misalignment of the light emitting element, it is not necessary to select a product based on variations in the position, tilt, or brightness or chromaticity of the light emitting element, reducing the work and cost required for the selection, and reducing the cost of the product. Can be provided.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a main part of a backlight structure of a liquid crystal display device according to an embodiment of the present invention.
FIG. 2 is a plan view of the light emitting element and the like shown in FIG.
FIG. 3 is a cross-sectional view of a main part showing an FPC and the like hooked on a guide pin.
FIG. 4 is a cross-sectional view showing a structure for positioning a light emitting element in a backlight structure of a conventional liquid crystal display device.
5 is a plan view of the light emitting device and the like shown in FIG. 4. FIG.
6 is a cross-sectional view showing a state in which the FPC shown in FIG. 4 is hooked on a guide pin.
[Explanation of symbols]
2, 22 Frame 2a, 22a Guide pin 4, 24 Liquid crystal display panel 6, 26 Light guide plate 8, 28 Diffusion plate 10, 30 Flexible wiring board 12, 32 Light emitting element 16, 36 Axis 18, 38 Axis 30a First guide Hole 40 Guide plate 40a Second guide hole

Claims (4)

A liquid crystal display panel and a light guide plate are arranged in the frame, and a flexible wiring board on which a light emitting element is mounted is positioned on a guide pin provided on the frame so as to irradiate the light to the light guide plate. In liquid crystal display devices,
A first guide hole having an inner diameter loosely fitted to the guide pin is provided in the flexible wiring board,
A guide plate having a second guide hole adapted to the guide pin is attached to the flexible wiring board in correspondence with the position of the light emitting element,
A backlight structure of a liquid crystal display device, wherein the light emitting element is positioned by fitting the second guide hole located in the first guide hole into the guide pin. The first guide hole is disposed on an axis of the flexible wiring board, and the guide plate is positioned so that the second guide hole is positioned on an extension of the axis of the light emitting element. The backlight structure of the liquid crystal display device according to claim 1, wherein the backlight structure is attached. The first guide holes are provided in pairs with the light emitting element interposed therebetween, and the second guide holes of the guide plate are provided so as to be positioned in the first guide holes, respectively. 3. A backlight structure of the liquid crystal display device according to 1 or 2. 4. The backlight structure of a liquid crystal display device according to claim 1, wherein the guide plate is bonded to the flexible wiring board with an adhesive tape or an adhesive.

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