JP2006190722A - Lcd backlight employing light emitting diode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LCD backlight employing a light emitting diode in which utilization efficiency of light is enhanced and high luminance is attained while reducing the thickness and weight. <P>SOLUTION: An LED 2 is mounted on the upper surface of an insulating printed board 1, side face of the LED 2 is surrounded by a frame member 3 and a diffuser sheet 4 is arranged on the upper surface of the frame member 3 oppositely to the LED 2. A conical diffuser sheet supporting member 5 made of translucent resin is arranged between the printed board 1 and the diffuser sheet 4 substantially in the center of the printed board 1. An aluminium deposition or silver deposition reflecting film 6 having light reflecting function is formed on the side face of the diffuser sheet supporting member 5. A dark region on the diffuser sheet due to shadow of a column is eliminated while preventing the diffuser sheet from bending, utilization efficiency of light of LED is enhanced by the reflecting film, and the number of LEDs can be decreased resulting in an LCD backlight employing a light emitting diode in which high luminance can be attained while reducing the thickness and weight. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an LCD backlight using a light emitting diode that irradiates a liquid crystal display device from the back side.

  In recent years, a liquid crystal display device having a thin and easy-to-see backlight mechanism has been widely used as a display device of various electronic devices such as a notebook personal computer, a PDA, and a mobile phone equipped with an optical communication function. As such a backlight mechanism, a planar light source that irradiates the entire surface of the liquid crystal display device from the back side is used. As the planar light source, a light emitting source composed of a fluorescent lamp or a light emitting diode (LED) and the LED are used. It is common to have a diffuser plate that uniformly diffuses the irradiated light to the LCD side. In particular, a planar light source using an LED or the like as a light emitting source is often used for the purpose of downsizing, thinning, and long life.

  When white illumination light is emitted by such a planar light source and white illumination is to be applied to a panel or the like, a white fluorescent lamp is used as the light emission source. In the case of LEDs, red (R), green (G ), Blue (B) high-intensity LEDs are generally turned on simultaneously or in a time-division manner to synthesize white light. More recently, in the case of LEDs, white LEDs that emit light close to white have been developed and used. By using this white LED, a planar light source intended for white illumination can be formed with a small and simple configuration. (For example, see Patent Document 1)

As shown in FIG. 3, the LCD backlight using the light emitting diode disclosed in Patent Document 1 described above has a plurality of LEDs (light emitting diodes) 11 on a predetermined position on the upper surface of an insulating printed board 10. To implement. A side surface of the LED 11 is surrounded by a reflection frame (frame member) 12, and a scattering sheet (diffusion plate) 13 is disposed on the upper surface of the frame member 12 so as to face the LED 11. Further, white glossy printing is performed on the surface of the printed circuit board 10 in order to reflect the light of the LED 11 upward, thereby constituting an LCD backlight.
Japanese Utility Model Publication No. 64-49886 (page 3, FIG. 1)

  In the structure of the LCD backlight described above, the diffusion plate 13 is supported only by the outer peripheral portion of the frame member 12 disposed on the printed circuit board 10, so that the diffusion plate 13 is thin as shown in FIG. The central part of the diffusion plate 13 is bent. Therefore, the emitted light from the diffusion plate 13 is scattered, and the utilization efficiency is lowered as LCD backlight illumination. If the thickness of the diffusing plate 13 is increased in order to prevent the diffusing plate 13 from being bent, the LCD backlight device is reduced in weight and thickness.

  Therefore, in order to prevent the diffusion plate 13 from being bent even if it is thin, a cylindrical shape is formed between the printed board 10 and the diffusion plate 13 in the vicinity of the substantially central portion of the printed board 10 as shown in FIG. The diffusion plate support member 14 having been subjected to the above was built, and measures to prevent the diffusion plate 13 from being bent were taken.

  The problem to be solved is that, as described above, by arranging the diffusion plate support member 14 having a cylindrical shape, the upper portion of the cylinder is shielded from light, so that a dark region 15 is formed on the upper surface of the diffusion plate 13. There was a problem that.

  In order to eliminate the above-mentioned drawbacks, the object of the present invention is to improve the utilization efficiency of light, and enable an LCD backlight using a light-emitting diode, which is thin, light and high in luminance. is there.

  In order to solve the above problems, an LCD backlight using a light emitting diode according to the present invention has an LED mounted on an upper surface of an insulating printed board, and surrounds the side surface of the LED with a frame member so as to face the LED. In the direct type LCD backlight in which a diffusion plate is provided on the upper surface of the frame member, a diffusion plate support member is provided between the printed board and the diffusion plate. is there.

  Further, the diffusion plate support member is disposed at a substantially central portion of the printed circuit board, and the shape thereof is a conical column.

    The diffusion plate support member is made of a translucent resin.

  Further, a light reflection function is added to the side surface of the diffusion plate support member.

  The reflection function added to the side surface of the diffusion plate support member is characterized in that a reflection film such as aluminum vapor deposition or silver vapor deposition is formed on the surface.

  The LCD backlight using the light emitting diode of the present invention supports the diffusion plate with a conical support column having a light reflecting function, thereby preventing the diffusion plate from being bent and at the same time being dark due to the shadow of the support column on the diffusion plate. Light-emitting diode that eliminates the generation of area and improves the light efficiency of LED light by using the reflection function on the side of the column, reducing the number of LEDs, making it thinner, lighter, and brighter The LCD backlight which uses is provided.

  An LCD backlight using the light emitting diode of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of an LCD backlight device according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an insulating printed circuit board made of glass epoxy resin or the like, and a predetermined conductive pattern (not shown) on the upper surface, an external connection electrode on the lower surface, and a through hole for connecting the upper and lower surface electrodes. An electrode is formed. A plurality of LEDs 2 are mounted at predetermined positions on the upper surface side of the printed circuit board 1.

  The side surface of the LED 2 is surrounded by a frame member 3, and a diffusion plate 4 is disposed on the upper surface of the frame member 3 so as to face the LED 2. In the vicinity of the substantially central portion of the printed circuit board 1, a diffusion plate support member 5 made of a translucent resin having a conical shape is built between the printed circuit board 1 and the diffusion plate 4, and at the tip of the conical support column. The diffusion plate 4 is supported so as to contact the lower surface.

  The operation and effect of the LCD backlight configured as described above will be described. Since the conventional diffuser plate support member has a cylindrical shape, the upper part of the diffuser plate is shielded from light and a dark region is generated. However, in this embodiment, the conical tip of the diffuser plate support member is supported by substantially point contact. The upper part of the diffusing plate is not shielded, and therefore no dark area is generated. Further, since the diffusion plate support member is a translucent resin, the light emitted from the LED can be used effectively.

FIG. 2 is a cross-sectional view of an LCD backlight device according to Embodiment 2 of the present invention. The difference from the first embodiment described above is that a light reflection function is added to the side surface of the diffusion plate support member.
In FIG. 2, a reflective film 6 such as aluminum vapor deposition or silver vapor deposition is formed on the side surface of a diffusion plate support member 5 made of a conical translucent resin.

  The operation and effect of the LCD backlight having the above configuration further improves the utilization efficiency of the irradiation light of the LED by performing a surface treatment on the side surface of the diffusing plate supporting member so as to obtain a high reflectance. Similar to the first embodiment, the diffusion plate can be prevented from being bent, and a dark region is not formed in the light emitted from the diffusion plate.

  As described above, the LCD backlight of the present invention can reduce the number of LEDs as the brightness increases, and the cost can be expected to be reduced accordingly. In addition, it is possible to provide an LCD backlight using a light-emitting diode, which can reduce the thickness, weight, and brightness of the LCD backlight without increasing the thickness of the diffusion plate.

It is sectional drawing of the LCD backlight apparatus concerning Example 1 of this invention. It is sectional drawing of the LCD backlight apparatus concerning Example 2 of this invention. It is sectional drawing of the LCD backlight apparatus concerning a prior art. It is sectional drawing of the other LCD backlight apparatus concerning a prior art.

Explanation of symbols

1 Printed circuit board 2 LED
3 Frame member 4 Diffusion plate 5 Diffusion plate support member 6 Reflective film

Claims (5)

  A light emitting diode (LED) mounted on the upper surface of an insulating printed circuit board, the side surface of the LED is surrounded by a frame member, and a diffusion plate is disposed on the upper surface of the frame member so as to face the LED An LCD backlight using a light emitting diode, wherein a diffusion plate support member is disposed between the printed circuit board and the diffusion plate.   2. The LCD backlight using a light emitting diode according to claim 1, wherein the diffusion plate support member is disposed at a substantially central portion of the printed circuit board, and the shape thereof is a conical column.   3. The LCD backlight using a light emitting diode according to claim 2, wherein the diffusion plate support member is made of a translucent resin.   The LCD backlight using the light emitting diode according to any one of claims 1 to 3, wherein a light reflecting function is added to a side surface of the diffusion plate support member. 5. The LCD backlight using a light emitting diode according to claim 4, wherein the reflective function added to the side surface of the diffusion plate support member is formed with a reflective film such as aluminum vapor deposition or silver vapor deposition on the surface thereof.

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