Patent ID: 8219003

Claim:
A drive control apparatus comprising: a drive motor configured to transmit a rotation drive force to a belt-like rotation member in order to rotate the belt-like rotation member; a pulse signal outputting unit configured to output a pulse signal at each predetermined position on the belt-like rotation member, while the belt-like rotation member is rotating; a pulse cycle measuring unit configured to measure a pulse cycle of the pulse signal, wherein the pulse cycle is a cycle of a rising or falling edge; a computation processing unit configured to compute a position error of the belt-like rotation member based on the pulse cycle and a desired pulse cycle, wherein the desired pulse cycle corresponds to a desired velocity of the belt-like rotation member; a drive control unit configured to control the drive motor based on the position error; and an edge time subtraction measuring unit, wherein the pulse signal outputting unit comprises at least two optical sensors placed along a moving direction of the belt-like rotation member at regular intervals and each of the optical sensors detects a plurality of optical markers that are arranged on the belt-like rotation member at regular intervals, and outputs a pulse signal, wherein the edge time subtraction measuring unit measures an edge time subtraction between at least two pulse signals that are output from the at least two optical sensors, and wherein the computation processing unit corrects the position error of the belt-like rotation member based on a pitch error calculated from the edge time subtraction of the at least two pulse signals and the ratio of the interval between the two optical sensors and the interval between the optical markers, wherein the computation processing unit stops computation of the position error when a pulse cycle output from one of the optical sensors indicates that a part is discontinuous, and starts computation of the position error based on the pulse signal output from the other optical sensor at the moment that the discontinuous part passes the other optical sensor, and wherein the computation processing unit stops computation of the position error by a selector being deselected, the selector being deselected in response to a counted value of an edge counter, receiving input from the at least two optical sensors, exceeding a threshold Cth, the exceeding indicating a discontinuation of the optical markers on the belt-like rotation member.