Image sensor with photosensitive thin film transistors and dark current compensation
First Claim
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1. An image sensor for sensing a received image, comprising:
- a substrate;
a photo TFT disposed on the substrate to generate a photocurrent responsive to the received image, the photo TFT including,a source electrode coupled to a first bias line,a gate electrode coupled to a second bias line,a drain electrode, anda semiconductor layer coupled to the source and drain electrodes; and
a storage capacitor disposed on the substrate and coupled to the source electrode and drain electrode of the photo TFT, the storage capacitor storing a charge generated by the photocurrent and comprising a stacked capacitor including a top electrode, a bottom electrode and an electrode disposed between the top electrode and the bottom electrode.
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Abstract
An image sensor array includes image sensors having photo TFTs to generate photocurrent in response to received images. The photo TFTs each have their respective gate electrodes and source electrodes independently biased to reduce the effects of dark current. Storage capacitors are coupled to each photo TFT and discharged upon generation of a photocurrent. Each storage capacitor is coupled to a readout TFT that passes a current from the storage capacitor to a data line. The photo TFT may be disposed above the storage capacitor to increase the exposed surface area of the photo TFT.
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Citations
23 Claims
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1. An image sensor for sensing a received image, comprising:
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a substrate; a photo TFT disposed on the substrate to generate a photocurrent responsive to the received image, the photo TFT including, a source electrode coupled to a first bias line, a gate electrode coupled to a second bias line, a drain electrode, and a semiconductor layer coupled to the source and drain electrodes; and a storage capacitor disposed on the substrate and coupled to the source electrode and drain electrode of the photo TFT, the storage capacitor storing a charge generated by the photocurrent and comprising a stacked capacitor including a top electrode, a bottom electrode and an electrode disposed between the top electrode and the bottom electrode. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An image sensor array for sensing a received image, comprising:
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a substrate; a plurality of bias lines disposed on the substrate; a plurality of data lines disposed on the substrate; a plurality of select lines disposed on the substrate; a plurality of photo TFTs disposed on the substrate to generate a photocurrent responsive to the received image, each photo TFT including, a source electrode coupled to a corresponding first bias line, a gate electrode coupled to a corresponding second bias line to provide a bias to the gate electrode independent of the bias to the source electrode, a drain electrode, and a semiconductor layer coupled to the source and drain electrodes; a plurality of storage capacitors disposed on the substrate, each storage capacitor coupled to the source electrode and drain electrode of a corresponding photo TFT, each storage capacitor storing a charge generated by the photocurrent and comprising a stacked capacitor including a top electrode, a bottom electrode and an electrode disposed between the top electrode and the bottom electrode; and a plurality of readout TFTs disposed on the substrate, each readout TFT including, a gate electrode coupled to a corresponding select line, a source electrode coupled to the drain electrode of a corresponding photo TFT and coupled to the storage capacitor, a drain electrode coupled to a corresponding data line, and a semiconductor layer coupled to the source and drain electrodes, wherein each readout TFT passes a current to a corresponding data line in response to the discharge of a corresponding storage capacitor. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. An image sensor for sensing a received image, comprising:
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a substrate; a photo TFT to generate a photocurrent responsive to the received image, the photo TFT including, a source electrode coupled to a first bias line, a gate electrode coupled to a second bias line, a drain electrode, and a semiconductor layer coupled to the source and drain electrodes; and a storage capacitor disposed between the substrate and the photo TFT and coupled to the source electrode and drain electrode of the photo TFT, the storage capacitor storing a charge generated by the photocurrent; wherein the storage capacitor comprises a stacked capacitor including a top electrode, a bottom electrode and an electrode disposed between the top electrode and the bottom electrode. - View Dependent Claims (22, 23)
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Specification