Hitachi Displays, Ltd.

Hitachi Display Devices, Ltd.

Panasonic Liquid Crystal Display Co., Ltd.

Hiroshi Tokuyama

Saburo Watanabe

Norihisa Fukayama

Seiichi Nishiyama

In a liquid crystal display device which uses light emitting diodes as a light source, the present invention provides a light source which can be effectively housed in a housing casing of a backlight even when an area of a printed circuit board is increased by taking radiation of heat from the light emitting diodes into consideration. A printed circuit board is formed by arranging light emitting diodes on a flexible substrate. The printed circuit board is formed with an area larger than an area of a light incident surface of a light guide plate, and is arranged to face the light incident surface of the light guide plate in an opposed manner. The light guide plate and the printed circuit board are housed in the inside of a housing casing, the printed circuit board is made foldable by forming slits in the printed circuit board thus enabling housing of the printed circuit board in the housing casing in a folded shape. Due to housing of the printed circuit board in a folded shape, a contact area of the printed circuit board with the housing casing is increased thus enhancing a heat radiation effect.

Liquid crystal display device

In a liquid crystal display device which uses light emitting diodes as a light source, a backlight can efficiently house a heat radiation plate even when an area of the heat radiation plate is increased by taking the radiation of heat from the light emitting diodes into consideration. Light emitting diodes are arranged on a metal substrate to form a plate-shaped light source portion. A heat radiation effect is enhanced by adhering a heat radiation plate to the plate-shaped light source portion. The heat radiation plate to which the plate-shaped light source is adhered is constituted as a housing casing thus efficiently housing the heat radiation plate. A problem which occurs due to the use of the metal-made housing casing can be overcome by mounting a resin-made light guide plate fixing member on the housing casing.

A planar illumination device is provided that can achieve even distributions of mixed colors and luminance, downsizing and weight saving without lowering the luminous efficiency of LED chips. In addition, a liquid crystal display device using the planar illumination device as a backlight is provided. A polygonal flat plate-like light guide plate GLB is combined with a plurality of LED chips DDDemitting light with different colors from each other to constitute a color mixing unit DUT. A plurality of the color mixing units are arranged on printed circuit boards RFB having a reflection function to constitute a planar illumination device. The planer illumination device is installed on the back of a liquid crystal display panel, thus constituting a liquid crystal display device.

Growing community of inventors

Mobara, Japan

Hiroshi Tokuyama