Radiant energy – Source with recording detector – Including a light beam read-out
Reexamination Certificate
2002-05-23
2004-05-18
Hannaher, Constantine (Department: 2878)
Radiant energy
Source with recording detector
Including a light beam read-out
C250S590000, C430S057800
Reexamination Certificate
active
06737667
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image recording medium including an electric accumulator that accumulates electric charges in a quantity corresponding to an electromagnetic wave irradiated for recording as electric charges for a latent image. The present invention also relates to an image retrieving method and an image retrieving apparatus to retrieve an electrostatic latent image recorded on the image recording medium.
2. Description of the Related Art
A conventionally-known method for use in medical radiography or the like is a method utilizing, for example, a radiation image recording medium (an electrostatic recorder) as a photoreceptor. The radiation image recording medium, which includes a photoconductor such as a selenium plate sensitive to radiations such as X-rays, is used as an image recording medium having an electric accumulator for accumulating electric charges in a quantity corresponding to irradiated electromagnetic waves for recording as electric charges for a latent image. In the foregoing method, X-rays are irradiated onto the radiation image recording medium to allow the electric charges in a quantity corresponding to the irradiated radiation to be accumulated in the electric accumulator inside the radiation image recording medium, whereby radiation image information is recorded as an electrostatic latent image. Moreover, the radiation image information is retrieved out of the radiation image recording medium by scanning the radiation image recording medium, on which the radiation image information is recorded, with a laser beam or a line light source (as disclosed in U.S. Pat. No. 4,535,468, for example). It is possible to attempt reduction of radiation dosage of a test subject and enhancement in diagnostic performance by use of the radiation image recording medium.
In Japanese Unexamined Patent Publication No. 2000-105297 and in Japanese Patent Application No. 10 (1998)-271374, there has already been disclosed a radiation image recording medium which is capable of combining high-speed response upon reading out and efficient extraction of signal charges, a recording apparatus for recording radiation image information on this radiation image recording medium, and an image retrieving method and an image retrieving apparatus for retrieving the radiation image information out of the radiation image recording medium, on which the radiation image information is recorded as the electrostatic latent image.
The method disclosed in Japanese Unexamined Patent Publication No. 2000-105297 includes the steps of using a radiation image recording medium including a first electrode layer which transmits radiation for recording or light emitted by excitation of the radiation, a recording photoconductive layer which takes on conductivity by receiving irradiation of the radiation for recording or the light, a charge transport layer which acts substantially as an insulator with respect to electric charges for a latent image and acts substantially as a conductor with respect to transported electric charges having a reverse polarity to the electric charges for a latent image, a retrieving photoconductive layer which takes on conductivity by receiving irradiation of an electromagnetic wave for retrieval, and a second electrode layer which transmits the electromagnetic wave for retrieval, the radiation image recording medium in which the foregoing constituents are stacked in accordance with the above order of enumeration, irradiating the radiation for recording onto the first electrode layer of the radiation image recording medium, recording radiation image information as an electrostatic latent image by allowing electric charges in a quantity corresponding to the dosage of the irradiated radiation to be accumulated in an electric accumulator formed substantially at an interface between the recording photoconductive layer and the charge transport layer, and obtaining the radiation image information by reading the recorded electrostatic latent image by irradiation of the electromagnetic wave for retrieval.
In addition, there has also been disclosed a radiation image recording medium, in which the second electrode layer is a stripe electrode composed of multiple line electrodes arranged in a stripe configuration which transmit the electromagnetic wave for retrieval. The foregoing radiation image recording medium can accumulate the electric charges for a latent image intensively in the electric accumulators corresponding to the respective line electrodes of the stripe electrode. Accordingly, it is possible to enhance sharpness of an image.
In the foregoing radiation image recording medium, if a direct-current voltage is applied such that the first electrode layer is charged as negative electric potential and the second electrode layer is charged as positive electric potential, and if the radiation which passed through an imaging object is irradiated onto the first electrode layer of the above-described radiation image recording medium, then charge pairs are generated on the recording photoconductive layer as corresponding to the dosage of the radiation owing to irradiation of the radiation that passed through the first electrode layer. Accordingly, negative electric charges are accumulated in the electric accumulator as the electric charges for a latent image, and the radiation image is recorded as the electrostatic latent image.
Moreover, if application of the direct-current voltage is discontinued and re-arrangement of electric charges are performed by short-circuiting the first electrode layer and the second electrode layer, and if the electromagnetic wave for retrieval is subsequently irradiated onto the second electrode layer of the radiation image recording medium, then the electromagnetic wave is transmitted through the second electrode layer and irradiated onto a retrieving photoconductive layer, whereby charge pairs are generated in the retrieving photoconductive layer. Among those charge pairs, positive electric charges are transmitted through the charge transport layer and coupled with negative electric charges accumulated in the electric accumulator. Meanwhile, negative electric charges cause electric discharge owing to re-coupling with positive electric charges that are charged on the second electrode layer. Retrieval of the electrostatic latent image is performed by detecting voltage variation generated between the first electrode layer and the second electrode layer owing to the electric discharge, as current variation with a current detection amplifier or the like.
Now, in the above-described radiation image recording medium, if a method such as vacuum deposition is used as a method for providing the first electrode layer on a surface of the recording photoconductive layer, such deposition of an electrode material takes place in a state that the radiation image recording medium is supported via a peripheral portion of the recording photoconductive Layer while the surface of the recording photoconductive layer is facing downward. Accordingly, an area of the first electrode layer to be provided becomes smaller than an area of the recording photoconductive layer by an area equivalent to an area of the peripheral portion. Even if the first electrode layer is provided by use of other fabricating methods, it is still difficult to form the first electrode layer exactly in the same area as the recording photoconductive layer. As a result, a small area without provision of the first electrode layer is incurred on the peripheral portion of the upper surface of the recording photoconductive layer. Meanwhile, if the first electrode layer is provided in the exactly same area as the recording photoconductive layer, then electric discharge against the second electrode layer tends to increase. Therefore, there may be a case that provision of the first electrode layer in a smaller area than the recording photoconductive layer as described above is rather preferred.
However, if the size of the first electrode layer is smaller th
Fuji Photo Film Co. , Ltd.
Gabor Otilia
Hannaher Constantine
Sughrue & Mion, PLLC
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