| 摘要 |
PCT No. PCT/JP97/02352 Sec. 371 Date Jun. 8, 1998 Sec. 102(e) Date Jun. 8, 1998 PCT Filed Jul. 7, 1997 PCT Pub. No. WO98/01303 PCT Pub. Date Jan. 15, 1998In an exposure apparatus for exposing a photosensitive medium using light-emitting elements, correction to account for environmental conditions at the time of exposure that change is performed by dynamically changing the value of current or voltage to be supplied to the LEDs. Thereby, control of exposure duration can be performed solely for expression of multi-gradation levels, so that a very high resolution is not required for the control of exposure duration. Therefore, it is possible to realize a low-price exposure apparatus capable of printing multi-gradation images. For exposure to a single color using a plurality of LEDs, the gradation level to be expressed by the individual LEDs is cyclically changed, so that the construction of gradation level control for each LED can be simplified. Further, since the LEDs can be used at substantially equal duties, the individual variation of LEDs does not evidently show. It is also possible to prevent an inconvenient incident where a particular LED deteriorates.
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