Patent ID: 7173677
Filing Date: 2007-02-06
Classification: G02B

Abstract:
1. A back light unit for a liquid crystal display device, the back light unit laminating at one sheet member chosen from a light diffusion sheet, a combination of a light diffusion sheet and a brightness rising sheet, and a reflective sheet on a light guide plate made of transparent synthetic resin arranged at a rear surface side of a liquid crystal display device, wherein tapered pins constructed in thin nose so as to break through the sheet member laminated on a surface side of the light guide plate are provided integratedly on the light guide plate, and the sheet member is fixed on the light guide plate by distorting of a tip end of the tapered pins by caulking using ultrasonic vibration, wherein, a radius of each of said tapered pins is reduced gradually from the light guide plate to a tip end of said each of said tapered pins.