Title:
IMAGE READER
Document Type and Number:
Japanese Patent JPH02260763
Kind Code:
A
Abstract:
PURPOSE:To prevent the generation of noise due to the temperature rise of a pulse motor winding and resonation at the inherent frequency of an image reader by switching a driving current to be supplied to a pulse motor in accordance with the forward and backward movement of a scanning optical system. CONSTITUTION:When the contents of an internal timer 8 are counted up, phase data CLK '1' is outputted to decide whether the scanning optical system is forward movement or not. In the case of forward movement, a phase step is increased and phase data are outputted to an output port 10. Phase exciting pattern signals 505, 506 are latched at a state '1' by a pulse motor driving clock (phase data CLK) 507 through latch circuits 12, 13 and supplied to a driver 14 as pulse motor exciting pulses 508, 509 and a motor driving current signal 510 is supplied from the driver 14 to the pulse motor 15. At the time of back scanning, the phase step is reduced. Consequently, noise due to the temperature rise of the pulse motor winding at a slow driving and resonation at the inherent frequency of the image reader can be suppressed at a low level.
Inventors:
ITAGAKI HIROSHI
Application Number:
JP8000989A
Publication Date:
October 23, 1990
Filing Date:
March 30, 1989
Export Citation:
Assignee:
CANON KK
International Classes:
G03B27/50; H04N1/04; (IPC1-7): G03B27/50; H04N1/04
Attorney, Agent or Firm:
Yoshikazu Tani