Method for illuminating a scanning surface with a light-emitting device and a light emitting device for a scanning device

    公开(公告)号:JP4785218B2

    公开(公告)日:2011-10-05

    申请号:JP23795499

    申请日:1999-08-25

    CPC classification number: H04N1/02835 H04N1/02815 H04N1/02855

    Abstract: A light source assembly (18) and method of providing illumination on a target surface utilize a fluorescent material to generate composite "white" light (38) from source light (36) of a particular color, i.e., a particular wavelength. The light source assembly is optimally designed for use in scanning devices (10), such as flat-bed color scanners, in which linear illumination is necessary to capture images, graphics, and/or text from a target scanned surface. In the preferred embodiment, the light source assembly includes a Gallium Nitride (GaN) based light emitting diode (LED) (26) that emits blue source light and a light transmitting rod lens (28; 50; 54; 56). The light transmitting rod lens is preferably a solid transparent structure, designed to receive the blue source light through one end of the rod and transmit a composite "white" light from the entire length of the rod, providing the desired linear illumination. The rod lens includes two fluorescent strips (30 and 32) and a non-fluorescent strip (34), located near the exterior surface of the rod. The two fluorescent strips operate to absorb the blue source light and to emit red light (40) and green light (42), while the non-fluorescent strip reflects the blue source light. The emitted red and green light, along with the reflected blue light (44), form the composite light that provides the linear illumination on the target surface.

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