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US 8,786,916 B2Granted
Method and device for driving light source, image reader, and image forming apparatus
AssigneeRicoh Company, Ltd.
InventorMasamoto Nakazawa
Life of this patent
Estimating the term…
Abstract
A light-source driving device includes a driving unit configured to drive a light source unit that emits light onto an object; and a driving control unit configured to control the driving unit to drive the light source unit in a first driving mode and a second driving mode. A light emission time of the light source unit is controlled in the first driving mode. An instantaneous value of a quantity of light of the light source unit being controlled in the second driving mode.
Claims20
A light-source driving device comprising:
- driving circuitry configured to drive a light source unit that emits light onto an object;
- and
- driving control circuitry configured to receive a first constant amplitude electric-current control signal in a first driving mode and a second constant amplitude electric-current control signal in a second driving mode and to control the driving circuitry to drive the light source unit in the first driving mode and the second driving mode,
- wherein a light emission time of the light source unit is controlled in the first driving mode, and an instantaneous value of a quantity of light of the light source unit is controlled in the first driving mode and in the second driving mode, and
- wherein, in the first driving mode, the instantaneous value of the quantity of light of the light source unit is based on the first constant amplitude electric-current control signal, and in the second driving mode, the instantaneous value of the quantity of light of the light source unit is based on the second constant amplitude electric-current control signal.
2 more elements
An image reader comprising:
- a light source unit configured to emit light onto an object;
- driving circuitry configured to drive the light source unit;
- generating circuitry configured to generate a first constant amplitude electric-current control signal in a first driving mode and a second constant amplitude electric-current control signal in a second driving mode for controlling driving of the light source unit;
- driving control circuitry configured to control the driving circuitry to drive the light source unit in the first driving mode and the second driving mode based on the first constant amplitude electric-current control signal and the second constant amplitude electric-current control signal, respectively, generated by the generating circuitry, a light emission time of the light source unit being controlled in the first driving mode, and an instantaneous value of a quantity of light of the light source unit being controlled in the first driving mode and in the second driving mode;
- and
- photoelectric converter configured to convert an accumulated quantity of reflected light from the object to which the light source unit emits light into electric energy for each of the first driving mode and the second driving mode, the accumulated quantity of light being accumulated during a charge storage time that depends on a corresponding one of the first driving mode and the second driving mode,
- wherein, in the first driving mode, the instantaneous value of the quantity of light of the light source unit is based on the first constant amplitude electric-current control signal, and in the second driving mode, the instantaneous value of the quantity of light of the light source unit is based on the second constant amplitude electric-current control signal.
4 more elements
A light-source driving method performed by an image reader, the light-source driving method comprising:
- generating a first constant amplitude electric-current control signal in a first driving mode and a second constant amplitude electric-current control signal in a second driving mode to control driving of a light source unit of the image reader, the light source unit emitting light onto a document;
- performing driving control by controlling driving circuitry of the image reader based on the first constant amplitude electric-current control signal and the second constant amplitude electric-current control signal generated to drive the light source unit in the first driving mode and the second driving mode, respectively, a light emission time of the light source unit being controlled in the first driving mode, and an instantaneous value of a quantity of light of the light source unit being controlled in the first driving mode and in the second driving mode;
- and
- performing photoelectric conversion by converting an accumulated quantity of reflected light from the document to which the light source unit emits light into electric energy for each of the first driving mode and the second driving mode, the accumulated quantity of light being accumulated during a charge storage time that depends on a corresponding one of the first driving mode and the second driving mode,
- wherein, in the first driving mode, the instantaneous value of the quantity of light of the light source unit is based on the first constant amplitude electric-current control signal, and in the second driving mode, the instantaneous value of the quantity of light of the light source unit is based on the second constant amplitude electric-current control signal.
2 more elements
Dependencies are inferred from the claim text.