BACK LIGHT DEVICE FOR LIQUID CRYSTAL DISPLAY AND LIQUID CRYSTAL DISPLAY DEVICE FORMED BY USING THE SAME

摘要

PURPOSE: To provide a back light for liquid crystal display enhanced in the efficiency of utilizing the quantity of the light emitted from a light source and a liquid crystal display device of high luminance formed by using this device. CONSTITUTION: This back light device for liquid crystal display is constituted by arranging a reflection plate 4, a light transmission plate 3 having a light source 1 on its side face, a circularly polarizing plate 7 consisting of a cholesteric liquid crystal layer exhibiting selective reflection within a range of 400 to 700mn, a quarter-wave plate 8 and a diffusion plate 5 or condensing plate in this order. This liquid crystal display device is constituted by using a liquid crystal cell formed by holding the oriented liquid crystal layer between substrates having electrodes and holding the cell between two sheets of polarizing plates on the outer side and the back light device for this liquid crystal display and is nearly 0 in the angle formed by the vibration plane of the linearly polarized light emitted from the back light device and the transmission axis of the polarizing plates with which the back light device comes into contact.