JPH0545653U - Back light - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To provide a backlight that is thin and plate-shaped and can be easily mounted on a liquid crystal display device. [Structure] An LED chip 1a arranged on a flexible wiring board 1 is replaced by a light-guiding portion 2a of a light guide plate 2 made of a translucent material.
The flexible wiring board 1 is disposed on the side surface of the light guide plate 2 so that the flexible wiring board 1 is housed in. The conductive terminal 1d of the flexible wiring board 1 is connected to the wiring on the liquid crystal display device side incorporating the backlight.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a backlight used in a liquid crystal display device requiring back lighting, and more particularly to a thin backlight using an LED (light emitting diode) chip as a light source.

[0002]

[Prior Art]

 Since the liquid crystal does not emit light by itself, the contrast is not sufficient in dark places such as at night and the display becomes difficult to see. For this reason, a backlight that illuminates the back surface is required when the device is intended to be used in any place such as a mobile device, day or night. In this case, the backlight is required to be as thin as possible.

Conventionally, cold cathode tubes, ELs, LEDs (light emitting diodes), etc. have been used as light sources for backlights, but LEDs that are inexpensive, have a relatively long life, and are also advantageous for downsizing, In particular, LED chips are most often used. A conventional example of a backlight using an LED chip is shown in FIG. A glass epoxy wiring board 5 is used as an electrode plate, an LED chip 5a is connected to a wiring pattern 5b, and leads 5c are connected as conductive terminals. After the projection 6a formed on the bottom of the polycarbonate reflection frame 6 is inserted into the mounting hole 5d of the glass epoxy wiring board 5, the projection 6a is heated and pressed to be deformed so that the glass epoxy wiring board 5 and the reflection frame 6 are formed. Integrate with. The reflection frame 6 is for positioning and mounting. Next, a substantially plate-shaped light guide member 7 is inserted into the upper opening of the reflection frame 6, and a diffusion plate 8 is arranged above the light guide member 7, that is, on the display surface side. .. The lower surface of the light guide member 7 is formed in a raised bottom shape so as not to contact the LED chip 5a mounted on the glass epoxy wiring board 5.

[0004]

[Problems to be solved by the device]

 However, in the configuration of FIG. 5, since the thickness of the reflection frame 6 and the glass epoxy wiring board 5 is added in addition to the light guide member 7, and the leads 5c project to the lower surface of the glass epoxy wiring board 5, As a whole, it tends to grow in the thickness direction. As described above, the configuration of FIG. 5 has a drawback in that the thickness of the backlight as a whole cannot be reduced to, for example, 3 mm or less, which is a problem in providing a thinner backlight.

The present invention has been made in view of the above points, and an object of the present invention is to provide a backlight in which the liquid crystal display device is thin as a whole as a thin plate. ..

[0006]

[Means for Solving the Problems]

 In order to achieve the above object, the backlight of the present invention uses a flexible wiring board in which a wiring pattern and conductive terminals are formed continuously on the wiring pattern on a base material, and an LED chip is wired on the flexible wiring board. The plate-shaped light guide made of a translucent material has a light-collecting part formed on the side surface, and a diffusing member is arranged on the irradiation surface side to face the irradiation surface. A reflecting member is arranged on the reflecting surface side. Then, the flexible wiring board is arranged on the side surface of the plate-shaped light guide so that the LED chip is arranged in the lighting portion of the plate-shaped light guide.

[0007]

[Action]

 The conductive terminal of the flexible wiring board arranged on the side surface of the plate-shaped light guide is connected to the wiring of another circuit by soldering or the like.

[0008]

【Example】

 The present invention will be described with reference to the drawings. First, FIG. 1 is an exploded perspective view of a preferred exemplary embodiment of the present invention, in which 1 is a flexible wiring board, 1a is an LED chip, 2 is a light guide plate, 2a is a light collecting part, 3 is a diffusion film, and 4 is a diffusion film. Is a reflective film. FIG. 2 is an enlarged view of the flexible wiring board 1, FIG. 2 (A) is a view from the LED chip 1a side, and FIG. 2 (B) is a view from the conductive terminal 1d side. .. A wiring pattern 1c is formed on the base material 1b, and conductive terminals 1d are formed on the two protruding portions of the base material 1b so as to be continuous with the wiring pattern 1c. Further, the LED chip 1a is attached so as to be connected to the wiring pattern 1c. When copper foil is used for the conductive terminals 1d and the conductive terminals 1d are folded back to bond the back surfaces of the base materials together, the total thickness of one base material and the adhesive layer (thickness of adhesive etc.) By making sure that the thickness of the copper foil does not exceed twice, it is possible to prevent cracks from forming at the folded back portion.

In this embodiment, the two conductive terminals 1d are folded back as shown in FIG. 2, but the layout of the conductive terminals 1d is adapted to the wiring structure on the side of the display device to be mounted. There is. This will be described with reference to FIG. FIG. 3 is an enlarged view of the flexible wiring board 1, and similarly to FIGS. 1 and 2, the conductive terminal 1d is formed on the same surface as the mounting surface of the LED chip 1a. Since the conductive terminal 1d is located in the protruding portion, it can be freely bent and arranged at any position according to the wiring on the liquid crystal display device side in which the backlight is incorporated.

FIG. 4 is an enlarged view of a flexible wiring board according to another embodiment of the present invention. This is an example of a double-sided flexible wiring board, and a conductive terminal 1d is formed on the surface opposite to the surface on which the LED chip 1a is attached through the through hole. By using double-sided ones, there is no need to fold it up like one-sided ones, and the thickness is half that of a single-sided one, so the lateral spread of the backlight can be suppressed. Further, as shown in FIG. 3, if the conductive terminal 1d is projected, it can be bent and arranged at any position. As described above, since it can be freely bent, it is extremely suitable for equipment that requires space saving, such as a liquid crystal display device that is required to be thin.

The size of the flexible wiring board is set so as to be within the size of the side surface of the light guide plate 2. Therefore, the LED chip, the wiring, and the substrate can be accommodated within the thickness of the light guide plate 2, and the upper and lower surfaces of the light guide plate 2 are flat surfaces without any unevenness. A film-like one can be easily arranged and a unitized backlight is completed.

In the embodiment, two LED chips are arranged on each of the two side surfaces of the light guide plate 2. However, on which side the LED chips are arranged and how many LED chips are arranged. Whether or not the light guide plate 2 is provided may be freely designed, and the planar shape of the light guide plate 2 may be circular or the like, and the present invention is not limited to this embodiment.

[0013]

[Effect of the device]

 As described above, when the backlight of the present invention is used, the flexible wiring board is about the size of the side surface of the light guide plate, and the light guide plate has a simple shape only forming the lighting part. Since it is a flat surface without a film, it is possible to use a film for diffusion and reflection, which makes it possible to provide a thin backlight with a total thickness of about 1 mm. Further, when arranging the flexible wiring board on the side surface of the light guide plate, it is easy to dispose the surface of the flexible wiring board with an adhesive or the like.

Since the conductive terminals are provided at any desired position on the side surface of the light guide plate, after the backlight is mounted on the display device, the wiring part on the display device side and the conductive terminal of the backlight are connected. For example, when connecting by soldering, the mounting work should be extremely easy. Similarly, since the conductive terminals are provided at any position on the side surface of the light guide plate, it is possible to arrange the liquid crystal display device in consideration of space saving so that the entire liquid crystal display device becomes thin.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an embodiment of the present invention.

FIG. 2 is an enlarged view of a flexible wiring board which is an essential part of the embodiment of the present invention, FIG. 2 (A) is a view seen from the LED chip side, and FIG. 2 (B) is a conductive terminal side. It is the figure seen from.

FIG. 3 is an enlarged view of a flexible wiring board which is a main part of the embodiment of the present invention.

FIG. 4 is an enlarged view of a flexible wiring board which is a main part of another embodiment of the present invention.

FIG. 5 is an exploded perspective view of a conventional example.

[Explanation of symbols]

 1 flexible wiring board 2 light guide plate 3 diffusion film 4 reflection film

Claims (1)

[Scope of utility model registration request] 1. A plate-shaped light guide body made of a translucent material and having a daylighting portion formed on its side surface, a diffusion member disposed on the irradiation surface side of the plate-shaped light guide body, and the irradiation surface. And a flexible wiring board in which conductive terminals are formed continuously with the wiring pattern and LED chips are connected to the wiring pattern and arranged. The wiring board is a backlight arranged on the side surface of the plate-shaped light guide so that the LED chip is arranged in the lighting portion.