Patent ID: 9336472
Filing Date: 2016-05-10
CPC Classification: G03G,G06K

Claim Text:
1. An image forming apparatus, comprising: a master control unit configured to operate in synchronization with a master clock signal which oscillates at a predetermined master frequency; a slave control unit configured to operate according to an operation instruction by the master control unit in synchronization with a slave clock signal which oscillates at a slave frequency lower than the master frequency; wherein the slave control unit includes: the master control unit includes: the clock error calculator uses the master clock signal to measure a clock number of the slave clock signal, measures a time required for measurement until a measurement value reaches a predetermined reference value after the measurement is started, using the timer, obtains the measured time as the cycle information, and calculates a first error value representing a difference or a ratio of a first unit oscillation time which is a result obtained by dividing the obtained time by the reference value and a reference oscillation time predetermined as a correct cycle of the slave clock signal as the error of the slave clock signal, the clock error calculator further uses the master clock signal to measure a clock number of the slave clock signal within a predetermined reference time, obtains the measured clock number as the cycle information, calculates a second error value representing a difference or a ratio of a second unit oscillation time which is a result obtained by dividing the reference time by the obtained clock number and the reference oscillation time, and calculates an average value of the first and second error values as the error of the slave clock signal.