X-ray or gamma ray systems or devices – Electronic circuit – With display or signaling
Reexamination Certificate
1998-05-20
2001-12-25
Porta, David P. (Department: 2662)
X-ray or gamma ray systems or devices
Electronic circuit
With display or signaling
C378S098800
Reexamination Certificate
active
06333963
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image sensing apparatus and method which form an image by using radiation including visible light, X-rays, and the like (which will be generically called light in the present invention) and, more particularly, to a -one- or two-dimensional image sensing apparatus such as a facsimile apparatus, a digital copying machine, a still camera, or a radiation image sensing apparatus, and an image sensing method.
2. Description of the Related Art
Various image sensing apparatuses using large sensors each having a -one- or two-dimensional array of image sensing elements, each using a monocrystalline Si sensor typified by a CCD sensor and a MOS sensor or a PIN sensor consisting of hydrogenated amorphous silicon (to be referred to as a-Si hereinafter) have been proposed.
As these image sensing apparatuses, in addition to image sensing apparatuses designed to convert a visible light image into an electrical signal, image sensing apparatuses designed to convert a radiation image into an electrical signal have also been developed with development in nuclear technology and advances in medical radiographic devices and nondestructive testing.
Many of these image sensing apparatuses, however, have S/N ratios of the order of -2- and 3-digit figures, and have not been required to have higher S/N ratios for the following reasons. There have been no A/D converters suited to high-precision digitization of outputs with high S/N ratios. In addition, since the data amount after conversion becomes large, limitations are imposed on memories and communications, resulting in poor operability. This has reduced the necessity of image sensing apparatuses with high S/N ratios.
With the recent remarkable developments in large-capacity memories and high-speed communications, great demands have arisen for image sensing apparatuses with high S/N ratios of the order of -4- and 5-digit figures.
In general, however, a decrease in S/N ratio is inevitably caused by variations in the manufacturing process and variations in fixed patterns and sensitivity. To prevent this, the fixed pattern and sensitivity variations are stored in a memory, and correction is performed in actual operation by using the photographic output and the information in the memory.
In this technique, however, since the data used for correction is obtained before photographing operation, the following problems are posed.
In general, in using an image sensing apparatus, the user selects operation conditions for the apparatus in accordance with the purpose of photography or the like. In addition, the components of the image sensing apparatus vary in characteristics with changes in temperature. Furthermore, various types of automatic control such as automatic exposure and automatic gain adjustment are activated during photographing operation to easily obtain optimal images without mistakes. That is, the conditions actually set for the photographing operation differ from the conditions set to generate the data used for correction. Since fixed pattern and sensitivity variations that cause a drop in S/N ratio slightly vary depending on these conditions, errors contained in the photographic output cannot be corrected perfectly. As described above, the differences between the conditions set to obtain the data used for correction and the conditions set for the actual photographing operation may pose a problem in obtaining image information with a high S/N ratio.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an image sensing apparatus and method which can obtain image information with a high S/N ratio by solving the problem that errors contained in a photographic output cannot be corrected perfectly in some cases owing to the differences between the conditions set to obtain the data used for correction and the conditions set for the actual photographing operation.
It is another object of the present invention to provide an image sensing apparatus which can acquire correction data after photographing operation under the same conditions as those for the photographing operation, and an image sensing method which can acquire correction data by reproducing the photographic conditions as needed.
It is still another object of the present invention to an image sensing apparatus and method which can acquire correction data regardless of the time required for setting various conditions for photographing operation, e.g., the angle and position of the object, a target portion of the object, the time required for determining the position of a patient, or the time required for the patient to hold his/her breath, i.e., can acquire correction data after photographing operation, thereby obtaining image information with a high S/N ratio by acquiring correction data under conditions similar to the conditions set for photographing operation by omitting only an object (to be photographed) even when correction data is obtained by irradiating photographing light.
It is still another object of the present invention to provide an image sensing apparatus having image sensing means including a plurality of photo-electric elements arranged -one- or two-dimensionally, comprising:
means for storing a photographic output (an image signal output) obtained in a photographic mode;
means for storing a photographic condition in the photographic mode;
means for obtaining a correction output in a correction mode activated using the stored photographic condition; and
means for correcting the photographic output by using the correction output.
It is still another object of the present invention to provide an image sensing apparatus comprising:
image sensing means including a plurality of photo-electric elements arranged -one- or two-dimensionally;
image information irradiation means including a light source for emitting photographing light for obtaining image information light to be incident on the photo-electric element;
photographic condition control means for controlling a photographic condition for at least the light source;
condition storage means for storing a set value set by the photographic condition control means;
photographic output storage means (image signal output storage means) for storing a photographic output (an image signal output) obtained in photographing operation;
means for obtaining a correction output by causing the photographic condition control means to perform set operation in accordance with the set value stored in the condition storage means;
an arithmetic processing circuit for correcting the photographic output stored in the photographic output storage means by using the correction output; and
system control means for controlling the respective means.
It is still another object of the present invention to provide an image sensing method for an image sensing apparatus including image sensing means including a plurality of photo-electric elements arranged -one- or two-dimensionally, image information irradiation means including a light source for emitting photographing light for obtaining image information light to be incident on the photo-electric element, photographic condition control means for controlling a photographic condition for at least the light source, photographic output storage means for storing a photographic output, and condition storage means for storing a condition automatically controlled by the photographic condition control means, comprising the steps of:
causing the image information irradiation means to irradiate the image sensing means with image information light while operating the photographic condition control means to obtain a desired photographic output, causing the photographic output storage means to store the photographic output, and at the same time, causing the condition storage means to store a set value selected by the photographic condition control means; and
causing the photographic condition control means to perform set operation in accordance with the set value stored in the condition storage means, setting an o
Endo Yutaka
Kaifu Noriyuki
Kameshima Toshio
Kobayashi Isao
Nonaka Hideki
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Porta David P.
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