Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Reexamination Certificate
1999-12-27
2002-09-24
Allen, Stephone (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
C250S559450, C382S168000
Reexamination Certificate
active
06455832
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and device for discriminating defects of detecting elements constituting a solid-state detector, and more specifically, to a defect discriminating method and a defect discriminating device for discriminating the defective elements among a number of detecting elements constituting a solid-state image sensor, such as a CCD image sensor which detects visible light and outputs an image signal, and a radiation solid-state detector or the like which detects radiation and outputs an image signal.
2. Description of the Prior Art
Up to now, solid-state image sensors such as a CCD image sensor which detects visible light and outputs an image signal have been widely used in such applications as video cameras and digital still cameras. This solid-state image sensor comprises a number of photoelectric transducers arranged in the form of a matrix (for color applications, a color filter is further overlaid upon each photoelectric transducer), outputting an image signal carrying visible image information as two-dimensional matrix information.
Nowadays, in the field of radiation photographing for medical diagnosis, a variety of radiation solid-state detectors which detect radiation and output an image signal (mainly consisting of semiconductors) have been proposed and put to practical use. As a typical one of the various types of radiation solid-state detectors proposed, the radiation solid-state detector of photoelectric conversion type, which reads out the stored charges (also called the “latent image charges”) carrying image information by means of thin film transistors (TFTs) (Japanese Unexamined Patent Publication No. 59 (1984)-211263, Japanese Unexamined Patent Publication No. 2 (1990)-164067, PCT International Publication No. WO92/06501, SPIE Vol. 1443 Medical Imaging V; Image Physics (1991), p.
108-119
, etc.), the radiation solid-state detector of direct conversion type (MATERIAL PARAMETERS IN THICK HYDROGENATED AMORPHOUS SILICON RADIATION DETECTORS, Lawrence Berkeley Laboratory. University of California, Berkeley. Calif. 94720 Xerox Parc. Palo Alto. CA 94304, Metal/Amorphous Silicon Multilayer Radiation Detectors, IEE TRANSACTIONS ON NUCLEAR SCIENCE. VOL. 36. NO. 2. APRIL 1989, Japanese Unexamined Patent Application No. 1 (1989)-216290, etc.), and the radiation solid-state detector of improved direct conversion type, a mode of direct conversion type, (also called “light reading type”), in which the reading light is projected for scanning and reading out the latent image charges, are available.
Here, with the radiation solid-state detector of improved direct conversion type, a mode of direct conversion type, i.e., a mode in which the electromagnetic radiation (for example, visible light) for reading is projected for scanning and reading out, which has been proposed in Japanese Patent Application No. 10 (1998)-232824 by the present applicant, a first conductor layer having a permeability to radiation for recording, a photoconductive. layer for recording which exhibits a photoconductive phenomenon (exactly a radiation-conductive one), when irradiated with the radiation for recording which has penetrated through the first photoconductive layer, a charge transporting layer which acts almost as an insulator for a charge having the same polarity as that of the charges provided in the first conductor layer, while acting roughly as a conductor for a charge having a polarity opposite to that of the charges, a photoconductive layer for reading which exhibits a photoconductive phenomenon (exactly an electromagnetic radiation-conductive phenomenon), when irradiated with radiation for reading, and a second conductor layer having a permeability to electoromagnetic radiation for reading, are stacked together in this order, and the latent image charges carrying image information are stored on the boundary surface between the recording photoconductive layer and the charge transporting layer. The first conductor layer and the second conductor layer each act as an electrode. With this mode, the detecting element mainly consists of a photoconductive layer for recording, a charge transporting layer, and a photoconductive layer for reading.
With this improved direct conversion type of radiation solid-state detector, as modes in which the electrostatic latent image carried by the latent image charges are read out, the mode in which the second conductor layer (hereafter called the “reading electrode”) is formed in a flat sheet, and this reading electrode is scanned with a spot-like beam of a laser or other type of reading light to detect the latent image charges, and the mode in which the reading electrode is provided as stripy electrodes, and the line light sources extending in the direction approximately perpendicular to the longitudinal direction of the stripy electrodes are scanned along the longitudinal direction of the stripy electrodes to detect the latent image charges, are available. With the radiation solid-state detector, whichever reading mode it adopts, it provides a two-dimensional radiation solid-state detector in which a plurality of detecting elements, each of which corresponds to a pixel, are arranged practically in the form of a matrix. The word “practically” is used in the above statement because it cannot be said that, with the detector itself, the individual detecting elements are arranged in the form of amatrix. However, in the process in which an image signal obtained by reading out the latent charges is processed, a sampling point corresponds to a pixel, for example. With a radiation solid-state detector in which the reading electrode is provided as stripy electrodes, the stripy electrodes define the pixel points for the direction of arrangement.
With any one of the above-mentioned various types of radiation solid-state detectors, the solid-state detecting elements are arranged in the form of a matrix, and an image signal carrying a radiation image is output as two-dimensional matrix information.
Hereinbelow, a solid-state image sensor which detects visible light and outputs an image signal carrying visible image information, and a radiation solid-state detector which detects radiation and outputs an image signal carrying radiation image information are collectively referred to as “solid-state detectors”. This solid-state detector may not only be two-dimensional, but also one-dimensional.
A variety of elements, such as the photoelectric transducer constituting a solid-state image sensor, and the solid-state detecting elements constituting a radiation solid-state detector (described later) are collectively called “detecting elements”.
Incidentally, with the above-stated solid-state detector, adherence of dirt during manufacturing, occurrence of scratches in service, etc. may cause a so-called pixel defect, in other words, a phenomenon in which a detection signal is not normally outputted from a specific detecting element of the detecting elements constituting the solid-state detector.
As stated above, this pixel defect is caused by dirt, etc., and is so fine that it is extremely difficult to see by visual inspection. Therefore, a variety of methods which use the digital image processing technology to carry out automatic discrimination of the image defect have been proposed (for example, Japanese Unexamined Patent Publication No. 10 (1998)-133309).
With the defect discriminating method as given in this citation, a flat field image is read out while the recording member (equivalent to the solid-state detector as mentioned in the present specification) is exposed to flat field light, a smooth background image is generated, by removing a value corresponding to it from the pixel value of the flat field image, a residual image is obtained (equivalent to passing through a low-pass filter), and when comparison of the threshold value defined by the dispersion of the noise distribution with the absolute value of the residual image indicates that the absolute value of the residual image is greater t
Allen Stephone
Fuji Photo Film Co. , Ltd.
Spears Eric
LandOfFree
Defect discriminating method and device for solid-state... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Defect discriminating method and device for solid-state..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Defect discriminating method and device for solid-state... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2911635