US Patent No. 9,250,562

IMAGE FORMING APPARATUS


Patent No. 9,250,562
Issue Date February 02, 2016 
Title Image Forming Apparatus
Inventorship Daisuke Akagi, Tokyo (JP)
Assignee CANON KABUSHIKI KAISHA, Tokyo (JP)

Claim of US Patent No. 9,250,562

1. An image forming apparatus comprising:
a light source including a plurality of light-emitting portions that are each configured to emit a light beam for exposing
a photosensitive member;

a first light receiving unit configured to receive a plurality of light beams emitted from the plurality of light-emitting
portions;

a deflection unit configured to deflect a plurality of light beams emitted from the plurality of light-emitting portions,
such that the plurality of light beams scan the photosensitive member;

a second light receiving unit configured to, in response to receiving a light beam deflected by the deflection unit, generate
a detection signal indicating that the light beam has been received;

a current control unit configured to execute light power control of causing the plurality of light-emitting elements to emit
light individually and controlling a driving current which is supplied to each of the plurality of light-emitting portions
based on a light reception result of the first light receiving unit receiving a light beam emitted from each of the plurality
of the light-emitting portions, and supply a driving current with a pre-determined value to at least a second light-emitting
portion among the plurality of light-emitting portions, the current control unit being configured to supply driving currents
to a first light-emitting portion and the second light-emitting portion among the plurality of light-emitting portions such
that light beams emitted from the first light-emitting portion and the second light-emitting portion are incident on the second
light receiving unit in sequence; and

a timing control unit configured to measure a time interval between a first detection signal generated due to the second light
receiving unit receiving a light beam from the first light-emitting portion and a second detection signal generated due to
the second light receiving unit receiving a light beam from the second light-emitting portion, and based on the time interval,
control relative emission timings according to which the plurality of light-emitting portions emit the plurality of light
beams,

wherein the current control unit is configured to:
cause the second light receiving unit to generate the first detection signal by supplying, to the first light-emitting portion,
a driving current with a value based on a light reception result of the first light receiving unit receiving the light beam
emitted from the first light-emitting portion; and

cause the second light receiving unit to generate the second detection signal by supplying a driving current with a pre-determined
value to the second light-emitting portion.