Patent ID: 6181378
Filing Date: 2001-01-30
Classification: H04N

Abstract:
An image reading device, comprising:a focusing lens for forming an image of an object;a linear image sensor for capturing said image, said image sensor including a plurality of image receiving elements arranged in a line along a predetermined direction, said plurality of image receiving elements outputting image signals corresponding to said image;a contrast detecting system which detects contrast data representative of a contrast of said image based on said image signals;a rotatable mirror arranged between said object and said focusing lens, said rotatable mirror being rotatable about an axis parallel to said predetermined direction and reflecting light from said object towards said focusing lens;a driving mechanism which moves at least one of said focusing lens and said image sensor to change a distance therebetween; anda focusing condition judging system which controls said contrast detecting system to detect said contrast data, controls said driving mechanism to move said at least one of said focusing lens and said image sensor, and determines an in-focus condition of said image in accordance with contrast data having a maximum value, which is obtained for various values of said distance between said focusing lens and said image sensor.