Photosensitive chip having transfer circuits which compensate for shielded test photosensors
AssigneeXerox Corporation
InventorsPaul A. Hosier, Jagdish C. Tandon
Life of this patent
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Abstract
A photosensitive device includes a plurality of active photosensors, for receiving light from an original image, and at least one dark photosensor. The dark photosensor is shielded with a light shield so that it receives no light, and is used to establish a dark offset for the device. Each active photosensor and the dark photosensor have associated therewith an individual transfer circuit, including a reset node having a capacitance associated therewith. The capacitance of the reset node for the dark photosensor is selected to compensate for the extra capacitance created by the light shield.
Claims7
A photosensitive apparatus, comprising:
- a channel for accepting video signals therethrough;
- a first photosensor;
- a first transfer circuit operatively disposed between the first photosensor and the channel, including a first reset node having a first reset capacitance associated therewith, the first reset node being adapted to store a charge related to an output signal from the first photosensor;
- a second photosensor;
- a light shield disposed over the second photosensor, preventing the second photosensor from receiving light;
- a second transfer circuit operatively disposed between the second photosensor and the channel, including a second reset node having a second reset capacitance associated therewith, the second reset node being adapted to store a charge related to an output signal from the second photosensor, the second reset capacitance being not equal to the first reset capacitance.
A photosensitive apparatus, comprising:
- a channel for accepting video signals therethrough;
- a first photosensor;
- a first transfer circuit operatively disposed between the first photosensor and the channel, the first transfer circuit including means for applying a fat zero voltage to the first photosensor and a first reset node having a first reset capacitance associated therewith, the first reset node being adapted to store a charge related to an output signal from the first photosensor;
- a second photosensor;
- a light shield disposed over the second photosensor, preventing the second photosensor from receiving light;
- a second transfer circuit operatively disposed between the second photosensor and the channel, including means for applying a fat zero voltage to the second photosensor and a second reset node having a second reset capacitance associated therewith, the second reset node being adapted to store a charge related to an output signal from the second photosensor, the second reset capacitance being preselected to compensate within the second transfer circuit for a light-shield capacitance associated with the second photosensor.
Dependencies are inferred from the claim text.