Read-out apparatus for an image detector

Radiant energy – Source with recording detector – Including a light beam read-out

Reexamination Certificate

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C250S580000

Reexamination Certificate

active

06376857

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a read-out apparatus for an image detector. This invention particularly relates to a read-out apparatus for reading out an electrostatic latent image from an image detector, which generates a current in accordance with latent image charges carrying image information. This invention also relates to an image detecting and read-out apparatus comprising the read-out apparatus and the image detector, which are combined with each other.
2. Description of the Prior Art
Apparatuses utilizing image detectors, e.g. facsimile apparatuses, copying machines, and radiation image sensors, have heretofore been known.
For example, systems for recording and reading out radiation image information utilizing image detectors have heretofore been proposed. With the proposed systems for recording and reading out radiation image information, such that a radiation dose delivered to an object during a medical X-ray image recording operation may be kept small, and such that the image quality of an image and its capability of serving as an effective tool in, particularly, the efficient and accurate diagnosis of an illness may be enhanced, a photo-conductive material sensitive to X-rays, such as a selenium plate constituted of, e.g., a-Se, is employed as a photosensitive material or an electrostatic recording material. The photosensitive material (or the electrostatic recording material) is exposed to radiation, such as X-rays, carrying radiation image information, and latent image charges carrying the radiation image information are thereby accumulated in the photosensitive material. Thereafter, the photosensitive material is scanned with a laser beam, and currents occurring in the photosensitive material are detected via flat plate-shaped electrodes or comb tooth-shaped electrodes, which are located on opposite surface sides of the photosensitive material. In this manner, the electrostatic latent image represented by the latent image charges, i.e. the radiation image information, is read out. Such systems for recording and reading out radiation image information are described in, for example, U.S. Pat. Nos. 4,176,275, 5,440,146, and 5,510,626, “A Method of Electronic Readout of Electrophotographic and Electroradiographic Image,” Journal of Applied Photographic Engineering, Volume 4, Number 4, Fall 1978, pp. 178-182 (hereinbelow referred to as the Literature 1), and “23027 Method and device for recording and transducing an electromagnetic energy pattern,” Research Disclosure, Jun. 1983 (hereinbelow referred to as the Literature 2).
With the systems described in U.S. Pat. Nos. 4,176,275 and 5,510,626 and the Literature 1, a laser beam having been produced by an argon laser is expanded into a thin line-shaped light (a line light), and the line light is focalized by a cylindrical lens onto a photosensitive material, on which an electrostatic latent image has been recorded. In this manner, the photosensitive material is mechanically scanned with the line light, and the electrostatic latent image having been recorded on the photosensitive material is read out in a parallel manner with a plurality of comb tooth-shaped electrodes.
In the systems described in U.S. Pat. Nos. 4,176,275 and 5,510,626 and the Literature 1, such that the photosensitive material, from which the electrostatic latent image has been read out, may be used again for the recording of an electrostatic latent image, it is necessary to perform an erasing process for exposing the photosensitive material to uniform erasing light. In U.S. Pat. No. 5,510,626, a system provided with means for cutting out light having wavelengths for readout (wavelengths of blue light) as a light source for producing the uniform erasing light is disclosed.
With the system described in the Literature 2, pre-charging is performed with primary exposure, and thereafter final recording is performed.
Also, in Japanese Patent Application No. 10(1998)-232824, the applicant proposed an electrostatic recording material and a read-out apparatus for reading out radiation image information from the electrostatic recording material, on which the radiation image information has been recorded. The proposed electrostatic recording material comprises:
i) a first electrical conductor layer having permeability to recording radiation,
ii) a recording photo-conductive layer, which exhibits photo-conductivity when it is exposed to the recording radiation,
iii) a charge transporting layer, which acts approximately as an insulator with respect to electric charges having a polarity identical with the polarity of electric charges occurring in the first electrical conductor layer, and which acts approximately as a conductor with respect to electric charges having a polarity opposite to the polarity of the electric charges occurring in the first electrical conductor layer,
iv) a reading photo-conductive layer, which exhibits photo-conductivity when it is exposed to a reading electromagnetic wave, and
v) a second electrical conductor layer having permeability to the reading electromagnetic wave, the layers being overlaid in this order.
With the read-out apparatus described in Japanese Patent Application No. 10(1998)-232824, the electrostatic recording material, on which an electrostatic latent image has been recorded, is scanned with a reading electromagnetic wave having been produced by a light source, and the electrostatic latent image having been recorded on the electrostatic recording material is thereby read out. Japanese Patent Application No. 10(1998)-232824 also discloses a technique for performing pre-exposure prior to the recording of the electrostatic latent image and thereby preventing image quality from becoming bad due to a residual image or a dark latent image.
However, with the systems described in U.S. Pat. Nos. 4,176,275 and 5,510,626 and the Literature 1, wherein the photosensitive material is mechanically scanned with the line light, it is necessary for the cylindrical lens for the scanning, a mechanical scanning section, and the like, to be provided. Therefore, the problems occur in that a large number of parts must be provided, and the read-out apparatus cannot be kept cheap in cost and small in size. Also, the problems occur in that scanning nonuniformity ordinarily occurs with the mechanical scanning.
Further, as described in U.S. Pat. No. 5,510,626, such that the photosensitive material, from which the electrostatic latent image has been read out, may be used again for the recording of an electrostatic latent image, the systems described in U.S. Pat. Nos. 4,176,275 and 5,510,626 and the Literature 1 must be provided with means for cutting out light having wavelengths for readout from the light having been produced by the erasing light source. Therefore, the number of necessary parts increases even further, and the problems occur in that the read-out apparatus becomes expensive and large in size.
With the system described in the Literature 2, besides the light source for readout, a light source for the primary exposure must be provided. Therefore, the problems occur in that the read-out apparatus cannot be kept cheap in cost and small in size.
In Japanese Patent Application No. 10(1998)232824, it is not described clearly whether the scanning with reading light is or is not the mechanical scanning. However, from drawings for embodiments, it is presumed that the scanning with the reading light is the mechanical scanning. In cases where the scanning is the mechanical scanning, the same problems as those encountered with the systems described in U.S. Pat. No. 4,176,275, and the like, occur.
In cases where the scanning with the reading light is the mechanical scanning, the photosensitive material or the electrostatic recording material, on which the electrostatic latent image has been recorded, must be set on the read-out apparatus, and the electrostatic latent image must be read out with the read-out apparatus. Therefore, it is difficult to combine the photosensitive material, or the like, and th

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