| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the variation of excellent linear luminance by synchronizing the polarization control signal of an AC polarization are discharge lamp with the color channel exposing timing signal of a CCD line sensor. SOLUTION: A scanner illuminating system 22 is additionally provided with an AC polarization are discharge lamp 36 driven by a square wave (Vlamp and Ilamp ) generated by an electronic lamp ballast 38. The polarizing frequency fpoi of the driving current Ilamp is generated by means of a synchronizing timing device 50 and adjusted by a polarization control signal provided to the switch assembly 44 of the ballast 38. The timing device 50 incorporated a CCD line time generator 52 which generates a CCD-LINE signal for limiting the line time of each scanning line. The synchronization between the CCD-LINE signal and polarization control signal is made by passing the CCD-LINE signal through an integer multiplier 54 and a delay block 56 and, when the signals are synchronized to each other, polarization signals become coincident and always change their polarities during the predictable timeτof each scanning line.
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