JP2006189519A - Lcd backlight using light emitting diode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an LCD backlight using light emitting diodes, with which the utilization factor of the light is improved by forming a reflection film on the entire surface except for an LED mounting region. <P>SOLUTION: In the direct LCD backlight constructed by mounting the light emitting diodes (LEDs) 2 on the upper face of an insulating printed circuit board 1, surrounding a circumference of side faces of the LEDs 2 with a frame member, and arranging a diffusion plate 4 on the upper face of the frame member 3 and opposite to the LEDs 2, a reflection film 6 formed by vapor deposition of aluminum or silver, to be a reflection member of light, is arranged on an upper face of a resist 5 on the entire surface of the printed circuit board 1 except for the LED mounting region. Light form the LEDs is efficiently made incident on the diffusion plate. The number of the LEDs is optionally reduced. <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 member. 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 has a plurality of LEDs (light emitting diodes) 12 on a top surface of an insulating printed board 11 at a predetermined position. To implement. A side surface of the LED 12 is surrounded by a reflection frame (frame member) 13, and a scattering sheet (diffusion plate) 14 is disposed on the upper surface of the frame member 13 so as to face the LED 12. The upper surface of the printed board 11 is generally coated with a resist 15 except for the LED 12 mounting area. The printed circuit board 11 has a soldering pattern for soldering parts and a pattern for conduction. The solder spreads on the pattern, and the solder is attached to other than the soldering pattern. This also serves to protect the conductive pattern. It is often used that white gloss printing is applied to the resist 15 to also serve as a light reflecting surface. The LCD backlight is configured as described above.
Japanese Utility Model Publication No. 64-49886 (page 3, FIG. 1)

  In the structure of the LCD backlight described above, in general, most of the irradiation light of the LED 12 as a light source is emitted from the diffusion plate 14 to the LCD side as an LCD backlight, but a part of the light is reflected from the diffusion plate 14. Then, it returns to the printed board 11 side and is reflected upward again by the resist 15.

  As described above, the problem to be solved is that light emitted from the LED 12 returns to the LED mounting surface as reflected light, as shown in FIG. 3, except for light incident on the diffusion plate 14. The resist 15 coated outside the LED mounting region has a problem that the brightness is reduced because the returned light cannot be reflected more efficiently.

  In order to eliminate the above-described drawbacks, the present invention uses a light-emitting diode that can improve light utilization efficiency by forming a reflective film on the entire surface other than the LED mounting region. An LCD backlight is possible.

  In order to solve the above problems, an LCD backlight using a light emitting diode according to the present invention has a light emitting diode (LED) mounted on an upper surface of an insulating printed board, and surrounds the side surface of the LED with a frame member. In a direct type LCD backlight in which a diffusion plate is disposed on the upper surface of the frame member facing the LED, a light reflecting member is added to the entire surface except for the LED mounting area on the printed circuit board. Is.

  The light reflecting member added to the entire surface excluding the LED mounting region on the printed board is a reflecting film formed by aluminum vapor deposition or silver vapor deposition.

  The LCD backlight using the light emitting diode of the present invention efficiently reflects the reflected light returning from the diffusion plate with a reflection film made of aluminum vapor deposition or silver vapor deposition, so that the irradiation light of the LED is efficiently applied to the diffusion plate. The present invention provides an LCD backlight using a light-emitting diode that can be incident and can improve light use efficiency and brightness.

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

  1 and 2 relate to an embodiment of the present invention, FIG. 1 is a sectional view of an LCD backlight device, and FIG. 2 is a partially enlarged sectional view of FIG. 1 and 2, reference numeral 1 denotes an insulating printed board made of glass epoxy resin or the like, and a plurality of LEDs 2 are uniformly mounted at predetermined positions on the upper surface of the printed board 1. Thereafter, a reflection film 6 formed by, for example, aluminum vapor deposition or silver vapor deposition is provided as a reflection member on the upper surface of the conventional resist 5 over the entire region except the LED 2 mounting region. In this embodiment, the resist need not be white.

  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 to constitute an LCD backlight.

  The operation and effect of the LCD backlight configured as described above will be described. Light other than the light incident on the diffuser plate 4 returns to the LED mounting surface side as reflected light, is reflected by the reflective film 5 formed on the printed circuit board 1, and is incident on the diffuser plate 4 again. Irradiation light from the LED 2 can be efficiently incident on the diffusion plate 4, improving the light use efficiency and improving the luminance.

  As described above, the LCD backlight of the present invention can efficiently make the LED light incident on the diffusion plate. It is also possible to reduce the number of LEDs.

It is sectional drawing of the LCD backlight apparatus concerning the Example of this invention. It is a partial expanded sectional view of FIG. It is sectional drawing of the LCD backlight apparatus concerning a prior art.

Explanation of symbols

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

Claims (2)

  A light emitting diode (LED) is mounted on the upper surface of an insulating printed circuit board, the side surface of the LED is surrounded by a frame member, facing the LED, and a diffusion plate is disposed on the upper surface of the frame member. An LCD backlight using a light emitting diode, wherein a light reflecting member is added to the entire surface of the LCD backlight except for the LED mounting area on the printed circuit board. 2. The LCD back using a light emitting diode according to claim 1, wherein the light reflecting member added to the entire surface excluding the LED mounting area on the printed circuit board is a reflective film formed by aluminum vapor deposition or silver vapor deposition. Light.

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