Optical sheet, backlight, and liquid crystal display device

• Main Author: ARIMA MITSUO,SHIMIZU JUN,ODAGIRI HIROKAZU,OHTA EIJI,OBATA KEI
• Format: Patent
• Language: English
• Published: 11.04.2007
• Subjects: BLASTING; DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; FREQUENCY-CHANGING; FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMSTHEREOF; HEATING; INDEXING SCHEME ASSOCIATED WITH SUBCLASSES F21K, F21L, F21Sand F21V, RELATING TO THEFORM OR THE KIND OF THE LIGHT SOURCES OR OF THE COLOUR OF THELIGHT EMITTED; LIGHTING; MECHANICAL ENGINEERING; NON-LINEAR OPTICS; NON-PORTABLE LIGHTING DEVICES; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHERARTICLES, NOT OTHERWISE PROVIDED FOR; SYSTEMS THEREOF; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF; VEHICLE LIGHTING DEVICES SPECIALLY ADAPTED FOR VEHICLEEXTERIORS; WEAPONS

An optical sheet has a large number of cylindrical lens elements provided successively on one of principal faces thereof. The cylindrical lens elements have a finite focal distance on the emission side of illumination light and have an aspheric face of a leftwardly and rightwardly symmetric sectional shape. Where a Z axis is taken in parallel to a normal line direction to the optical sheet and an X axis is taken in a direction of the row of the cylindrical lens elements, a cross sectional shape of the cylindrical lens elements satisfies Z = X 2 / ( R + ¢ R 2 - ( 1 + K ) X 2 ) + AX 4 + BX 5 + CX 6 + ‹¯ (where R is the radius of curvature of a distal end vertex, K is a conic constant, and A, B, C, ··· are aspheric coefficients).