DESIGN PARAMETERS FOR THIN HOLLOW CAVITY BACKLIGHTS OF THE LIGHT-RECYCLING TYPE
    9.
    发明授权
    DESIGN PARAMETERS FOR THIN HOLLOW CAVITY BACKLIGHTS OF THE LIGHT-RECYCLING TYPE 有权
    光再生型薄型空腔背光源的设计参数

    公开(公告)号:EP2162785B1

    公开(公告)日:2018-03-07

    申请号:EP08755853.2

    申请日:2008-05-19

    IPC分类号: G02F1/13357 G02B6/00 F21V8/00

    摘要: A backlight unit (10), for a display or for general Iighting purposes, has a hollow cavity (16) instead of a solid Iight guide. One or more Iight sources (24a-c), e.g. LEDs, emit Iight into the cavity, which is formed by a front (12) and a back reflector (14). The backlight has either a directly-lit or an edge-lit configuration; it can have a Iarge area and still be thin; it consists of fewer components than conventional devices and its design permits the reuse of Iight reflected internally (Iight recycling). The unit emits Iight of a predefined polarisation and its viewing angle properties can be tailored. Light is uniformly distributed within the guide and the guide's output (20b, 20d) is substantially collimated. Such backlights occupy a specific region in a parameter space defined by two parameters: first, the ratio of the output emission area to the total source emission area should lie in the range from 0.0001 to 0.1 ; and second, the ratio of SEP (an average plan view source separation, which is a measure of the average spacing of the Iight sources in the plane of the unit) to the height of the cavity (H) should be in the range from 3 to 10. There is also a discussion of the required number of light sources N, their arrangement near the periphery of the cavity, as well as the shape and size of the output emission area. The backlight exhibits a minimum brightness uniformity (VESA) value, even when a subset of M adjacent sources is switched off (where M is at least 0.1 N or M>2 or both).