Flat panel X-ray imager with a grid structure
OwnerDenny Leeinventor
Life of this patent
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Abstract
A flat panel X-ray imager using an amorphous selenium detector which uses a polymer grid structure within the X-ray conversion layer to form an interface between the X-ray conversion layer and the pixel electrodes. The grid structure provides an additional physical barrier between pixel electrodes that reduces electrical bridging due to crystallization of the amorphous selenium due to temperature increases while also reducing the delamination temperature by providing a good anchor to the selenium, as well as a “cushion” for thermal expansion or contraction of the pixel electrodes. The grid can further include one or more grid electrodes for effecting avalanche-gain within the X-ray conversion layer while minimizing dark current entry into the selenium layer from the pixel electrode.
Claims30
A flat panel X-ray imager including a top electrode, a photoconducting layer for converting X-ray energy to electron-hole pairs, a thin film transistor layer having a gate electrode, a source electrode and a drain electrode coupled to a charge collection electrode, and a glass substrate, the flat panel X-ray imager being coupled to a power supply to generate a first electric field between the top electrode and the charge collection electrode, said thin film transistor layer further comprising:
- an upper portion comprising a grid, said grid comprising grid members that intersect to form openings that permit hole and electron movement to the charge collection electrode and wherein said grid expands and contracts with said thin film transistor layer during temperature changes.
A method for extending the temperature range of a flat panel X-ray imager, wherein the X-ray imager includes a top electrode, a photoconducting layer for converting X-ray energy to electron-hole pairs, a thin film transistor layer having a gate electrode, a source electrode and a drain electrode coupled to a charge collection electrode, and a glass substrate, said method comprising the steps of:
- forming a layer of a polymer over the thin film transistor before depositing the photoconducting layer over the thin film transistor;
- and
- patterning said layer of polymer to form a grid structure with openings to the charge collection electrode;
- depositing said photoconducting layer over said patterned layer of polymer;
- and
- applying the top electrode layer to form the X-ray imager.
A method of improving the conversion efficiency of a flat panel X-ray wherein the X-ray imager includes a top electrode, a photoconducting layer for converting X-ray energy to electron-hole pairs, a thin film transistor layer having a gate electrode, a source electrode and a drain electrode coupled to a charge collection electrode, and a glass substrate, said method comprising the steps of:
- (a) forming a first layer of a polymer over the thin film transistor before depositing the photoconducting layer over the thin film transistor;
- (b) forming a first layer of an electrical conductor over said polymer layer;
- (c) patterning said first layer of an electrical conductor;
- (d) depositing a second layer of polymer over said first layer of electrical conductor formed into said grid electrode;
- (e) patterning said layers of polymer to form a grid structure with openings to the charge collection electrode;
- (f) depositing said photoconducting layer over said grid structure;
- (g) applying the top electrode layer to form the X-ray imager;
- and
- (h) arranging said first layer of electrical conductor to be electrically energized.
Dependencies are inferred from the claim text.