US4998266A — Device for producing x-ray images by means of a p…

Claim 1

Independent Claim 143 words

X-ray imaging apparatus comprising: a source of X-ray radiation; a photoconductor responsive to said radiation incident thereon; means for charging the photoconductor to a first potential value relative to a second potential value, said photoconductor for converting said incident X-ray radiation into a charge pattern, said photoconductor discharging in accordance with the intensity of the incident radiation, at least a portion of said photoconductor discharging to a charge density corresponding to said second potential value in response to said incident radiation unless otherwise precluded; means for exposing said photoconductor to said radiation; and recharge means for simultaneously recharging the photoconductor during said exposure with a given charge to a third potential value intermediate said first and second potential values during exposure to said radiation to limit the decrease in said charge density of said photoconductor to a value corresponding to said third potential.

Claim 2

Dependent Claim 143 words

X-ray imaging apparatus comprising: a source of X-ray radiation; a photoconductor responsive to said radiation incident thereon; means for charging the photoconductor to a first potential value relative to a second potential value, said photoconductor for converting said incident X-ray radiation into a charge pattern, said photoconductor discharging in accordance with the intensity of the incident radiation, at least a portion of said photoconductor discharging to a charge density corresponding to said second potential value in response to said incident radiation unless otherwise precluded; means for exposing said photoconductor to said radiation; and recharge means for simultaneously recharging the photoconductor during said exposure with a given charge to a third potential value intermediate said first and second potential values during exposure to said radiation to limit the decrease in said charge density of said photoconductor to a value corresponding to said third potential.

Claim 3

Dependent Claim 87 words

The apparatus as claimed in claim 5, characterized in that the recharge means comprises a corona discharge device including a grid, said grid being placed at said first and third potentials and located between the discharge device and photoconductor adjacent to a surface of the photoconductor, said grid being dimensioned to cover the area of the photoconductor exposed during said x-ray radiation exposure, said third potential of said grid limiting the potential of the photoconductor surface to a value which corresponds approximately to the grid third potential.

Claim 4

Dependent Claim 72 words

The apparatus as claimed in claim 2, characterized in that the means for charging includes means for initially charging the photoconductor with a given first potential value applied to said grid prior to said photoconductor receiving said incident radiation and said recharge means includes means for reducing the given first potential value to the third potential value to charge the photoconductor with a potential of a lower value after such initial charging.

Claim 5

Dependent Claim 28 words

A device as claimed in claim 2, characterized in that there is provided a drive for producing a relative motion between the corona discharge device and the photoconductor.

Claim 6

Dependent Claim 40 words

The apparatus of claim 1 wherein said recharge means includes corona discharge means and grid means between said source and said photoconductor, said apparatus further including means for displacing the photoconductor, discharge means and grid means relative to said source.

Claim 7

Dependent Claim 91 words

An X-ray imaging apparatus comprising: a source of X-ray radiation; a photoconductor responsive to said radiation incident thereon for producing an image; means for exposing the photo conductor to said radiation; means for charging the photoconductor with a charge of a given level prior to exposing the photoconductor to said radiation; and means for charging the photoconductor with a charge of a different level than said given level simultaneously with the exposing of the photoconductor to said radiation to limit the discharge caused by said incident radiation to said different level.

Claim 8

Dependent Claim 91 words

An X-ray imaging apparatus comprising: a source of X-ray radiation; a photoconductor responsive to said radiation incident thereon for producing an image; means for exposing the photo conductor to said radiation; means for charging the photoconductor with a charge of a given level prior to exposing the photoconductor to said radiation; and means for charging the photoconductor with a charge of a different level than said given level simultaneously with the exposing of the photoconductor to said radiation to limit the discharge caused by said incident radiation to said different level.

Claim 9

Dependent Claim 53 words

The apparatus of claim 6 wherein each said means for charging comprises corona discharge means for charging the photoconductor in response to an applied voltage and means for setting the voltage applied to said discharge means to different respective values so as to charge said photoconductor with said given and different charge levels.

Claim 10

Dependent Claim 51 words

The apparatus of claim 7 wherein said means for exposing included aperture means for exposing a first portion of said photoconductor to said radiation and photoconductor displacement means for displacing the photoconductor to expose a second portion of the photoconductor to said radiation subsequent to the exposure of the first portion.

Claim 11

Dependent Claim 143 words

An X-ray imaging apparatus comprising: an X-ray source for emission of X-ray radiation; and a detection device for converting the X-ray radiation into a charge density pattern; said detection device comprising: a photoconductor at a first potential Vo; means for positioning the photoconductor for exposure to said radiation; charging means at a second potential Vgl different than the first potential Vo for charging the photoconductor with a charge density of a value corresponding to said second potential, the charge density being reduced over an area of said photoconductor exposed to said radiation in accordance with the radiation intensity and first potential value; and recharge means at a third potential Vg2 having a value intermediate that of the first and second potentials during said exposure for recharging to said third potential those portions of said area which otherwise would discharge to said first potential.

Claim 12

Dependent Claim 143 words

An X-ray imaging apparatus comprising: an X-ray source for emission of X-ray radiation; and a detection device for converting the X-ray radiation into a charge density pattern; said detection device comprising: a photoconductor at a first potential Vo; means for positioning the photoconductor for exposure to said radiation; charging means at a second potential Vgl different than the first potential Vo for charging the photoconductor with a charge density of a value corresponding to said second potential, the charge density being reduced over an area of said photoconductor exposed to said radiation in accordance with the radiation intensity and first potential value; and recharge means at a third potential Vg2 having a value intermediate that of the first and second potentials during said exposure for recharging to said third potential those portions of said area which otherwise would discharge to said first potential.

Claim 13

Dependent Claim 27 words

The apparatus of claim 9 wherein said means for positioning includes drive means for producing relative motion between said detection device and said source during said exposure.

Claim 14

Dependent Claim 41 words

The apparatus of claim 9 wherein said charging means comprises a corona discharge device at a fourth potential, a grid located between said device and said photoconductor and means for applying said second potential to said grid prior to said exposure.

Claim 15

Dependent Claim 22 words

The apparatus of claim 11 wherein the recharging means comprises means for applying said third potential to said grid during said exposure.

Claim 16

Dependent Claim 25 words

The apparatus of claim 11 wherein the discharge device and the grid cover substantially all of the area of the photoconductor exposed to said radiation.

Claim 17

Dependent Claim 98 words

A detection device for converting X-ray radiation into a charge density pattern, said device comprising: a photoconductor; means for positioning the photoconductor for exposure to said radiation; charging means for charging the photoconductor with a predetermined charge density to a first level, the charge density being reduced over an area of said photoconductor that is exposed to said radiation; and recharge means for recharging at least a portion of said area during exposure to said radiation when the charge density of said at least a portion of said area reaches a predetermined level different than the first level.

Claim 18

Dependent Claim 98 words

A detection device for converting X-ray radiation into a charge density pattern, said device comprising: a photoconductor; means for positioning the photoconductor for exposure to said radiation; charging means for charging the photoconductor with a predetermined charge density to a first level, the charge density being reduced over an area of said photoconductor that is exposed to said radiation; and recharge means for recharging at least a portion of said area during exposure to said radiation when the charge density of said at least a portion of said area reaches a predetermined level different than the first level.

Claim 19

Dependent Claim 25 words

The device of claim 14 wherein said means for positioning includes drive means for displacing said detection device relative to said radiation during said exposure.

Claim 20

Dependent Claim 62 words

The device of claim 14 wherein said charging means comprises a corona discharge device and a voltage control grid adjacent to the photoconductor at a first potential and said recharge means comprises placing said grid at a second potential different than the first potential for limiting the potential at the surface of the photoconductor to a value corresponding to said second potential.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1994-03-04	1994-09-03	1995-03-05	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1998-03-04	1998-09-03	1999-03-05	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2002-03-04	2002-09-03	2003-03-05	$7700.00	Window Closed / Lapsed

Device for producing x-ray images by means of a photoconductor

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