US Patent No. 9,225,867

IMAGE READING APPARATUS


Patent No. 9,225,867
Issue Date December 29, 2015
Title Image Reading Apparatus
Inventorship Kazunori Togashi, Toride (JP)
Assignee CANON KABUSHIKI KAISHA, Tokyo (JP)

Claim of US Patent No. 9,225,867

1. An image reading apparatus, comprising:
a first illumination unit and a second illumination unit each having a plurality of light sources, each illumination unit
is configured to irradiate light from the light source to a document reading position, the plurality of light source include
a first light source and a second light source, the first light source emits light in a first color and the second light source
emits light in a second color which is different from the first color;

a light receiving unit configured to receive reflection light from a document to which light is irradiated by the first illumination
unit and the second illumination unit, and to output, in response to a line synchronization signal, a first image signal in
accordance with received light quantity; and

a control unit configured to independently control 1) a turn-on period of each of the plurality of light sources in the first
illumination unit and 2) a turn-on period of each of the plurality of light sources in the second illumination unit, in response
to the line synchronization signal, wherein:

the control unit is further configured to control, when reading the document, to turn on the light source of a same color
by the first illumination unit and the second illumination unit within a line cycle defined in response to the line synchronization
signal, and;

the control unit is further configured to control the first illumination unit and the second illumination unit such that a
center position of the turn-on period of each of the plurality of the light sources in the first illumination unit coincides
with a center position of the turn-on period of each of the plurality of the light sources in the second illumination unit,
within the line cycle defined in response to the line synchronization signal.