Imaging device having a pixel structure with high dynamic range read-out signal
First Claim
1. A method for obtaining a read-out signal of a pixel having at least a photosensitive element and a charge storage node, the method comprising the steps of while acquiring charge carriers on said charge storage node during an integration period, said charge carriers being converted from radiation impinging on the photosensitive element:
- during a first time period of said integration period applying at least one reset pulse with a predetermined amplitude on said charge storage node, said pulse resetting incompletely the charge carriers acquired at the moment of applying said pulse; and
after each of at least one reset pulse further acquiring charge carriers on said charge storage node;
said method further comprising driving said pixel in weak inversion during a second time period after the last incomplete reset pulse of said integration period;
further acquiring charge carriers on said charge storage node during said second time period.
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Abstract
A method obtains a read-out signal of a pixel having at least a photosensitive element with a charge storage node. The method includes the steps of acquiring charge carriers, converted from impinging radiation on the photosensitive element, on the charge storage node, applying during the integration period at least one reset pulse, resetting incompletely the charge carriers acquired at the moment of applying the reset pulse, to obtain at least one linear response region for the pixel, and driving the pixel in weak inversion after the last incomplete reset pulse of the integration period so as to obtain a logarithmic response part. A corresponding pixel is also described.
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Citations
13 Claims
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1. A method for obtaining a read-out signal of a pixel having at least a photosensitive element and a charge storage node, the method comprising the steps of while acquiring charge carriers on said charge storage node during an integration period, said charge carriers being converted from radiation impinging on the photosensitive element:
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during a first time period of said integration period applying at least one reset pulse with a predetermined amplitude on said charge storage node, said pulse resetting incompletely the charge carriers acquired at the moment of applying said pulse; and
after each of at least one reset pulse further acquiring charge carriers on said charge storage node;
said method further comprising driving said pixel in weak inversion during a second time period after the last incomplete reset pulse of said integration period;
further acquiring charge carriers on said charge storage node during said second time period. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A pixel comprising:
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a photosensitive element;
a charge storage node, for storing a signal from the photosensitive element at a moment in time; and
a reset terminal on a reset transistor, said reset terminal equipped for applying a pulsed reset signal to the reset transistor, wherein said pixel further comprises driving means for driving the reset transistor in weak inversion. - View Dependent Claims (9, 10, 11, 12, 13)
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Specification