Patent ID: 8040577
Filing Date: 2011-10-18
Classification: H04N

Abstract:
1. An image reading apparatus comprising: a reading unit that reads image information of a reading target; a conveyance mechanism that conveys one of the reading unit and the reading target as a conveyance target; a reading control device that controls a moving speed of the conveyance target through the conveyance mechanism to thereby move the conveyance target at a constant speed in an image reading direction and periodically inputs a line start signal to the reading unit to thereby specify a reading start timing of a line image on the reading target so that the reading unit is caused to perform a reading operation of each line; a stop control device that stops a process by the reading control device under a predetermined condition; an encoder that outputs an event occurrence signal each time the conveyance target is moved by a predetermined distance, wherein a plurality of the line start signals are inputted to the reading unit within an output interval of the event occurrence signal in a case where the conveyance target moves at the constant speed; a position detection device that detects a current position of the conveyance target based on an event occurrence signal inputted from the encoder; an elapsed time measuring device that measures, with respect to each of the plurality of the line start signals, an elapsed time from a time point when a last event occurrence signal is inputted from the encoder until a time point when a line start signal is inputted to the reading unit; a time setting unit that sets an offset time based on the elapsed time measured by the elapsed time measuring device, the elapsed time being an elapsed time until a reading interruption time point when a last line start signal is inputted to the reading unit at or before a time point when a stop operation on the reading control device is performed by the stop control device; a position setting unit that sets, as a restart reference position, a position of the conveyance target detected by the position detection device correspondingly to an input of a last event occurrence signal inputted at or before the reading interruption time point; and a retreat control device that moves the conveyance target through the conveyance mechanism, when a stop operation is performed by the stop control device, in an opposite direction to the image reading direction to a position forward from the restart reference position set by the position setting unit, wherein the reading control device again moves the conveyance target, which has been moved by the retreat control device, at a constant speed in the image reading direction under a predetermined condition, inputs a line start signal to the reading unit when an offset time set by the time setting unit has elapsed from a time point when the conveyance target reaches the restart reference position set by the position setting unit, and subsequently periodically inputs a line start signal to thereby cause the reading unit to perform a reading operation from a point where the reading unit is located when the offset time has elapsed.