Patent ID: 6330096
Filing Date: 2001-12-11
Classification: G02B

Abstract:
A light-beam scanning type image reader comprising:light-beam generator which generates a light beam;first clock generator which generates a first clock pulse;second clock generator which generates a second clock pulse;a rotating polygon mirror, which rotates at a speed of rotation based on said first clock pulse generated by said first clock generator, for reflecting and deflecting said light beam so that said light beam is repeatedly scanned on a scan body in a horizontal scanning direction;vertical scanner which scans at least either one of said light beam or said scan body with respect to the other in a vertical scanning direction approximately perpendicular to said horizontal scanning direction at a speed based on said second clock pulse generated by said second clock generator;photoelectric detector which detects in sequence luminescent light emitted from said scan body by scanning said light beam on said scan body;sampling-clock generator which generates a fixed analog-to-digital (A/D) sampling clock pulse;analog-to-digital converter which converts analog signals, detected and obtained by said photoelectric detector, to digital signals according to said A/D sampling clock pulse generated by said sampling-clock generator;clock-cycle computer computes a cycle of said first clock pulse so that a number of said digital signals, obtained according to a horizontal length of a predetermined scan body, becomes equal to a first desired number of pixels, and for computing a cycle of said second clock pulse so that a number of said digital signals, obtained according to a vertical length of said predetermined scan body, becomes equal to a second desired number of pixels;clock-cycle storage which stores the cycle of said first clock pulse and the cycle of said second clock pulse computed by said clock-cycle computer; anddrive-clock controller which adjusts a cycle of said first clock pulse and a cycle of said second clock pulse, based on the cycle of said first clock pulse and the cycle of said second clock pulse stored in said clock-cycle storage.