Photography – Fluid-treating apparatus – Photographic medium or cartridge sensing
Reexamination Certificate
2003-03-28
2004-11-09
Rutledge, D. (Department: 2851)
Photography
Fluid-treating apparatus
Photographic medium or cartridge sensing
C396S570000, C396S575000
Reexamination Certificate
active
06814506
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a density correction method applied to image formation in a heat developing apparatus in which a photothermographic material including a heat-developable light-sensitive material and a light- anf heat-sensitive recording material is exposed to laser light, etc. The present invention also relates to a heat developing apparatus capable of density correction according to the method.
2. Description of the Related Art
Reduction of waste liquid in the medical field has been keenly demanded for environmental conservation and space saving. Too meet the demand, it has been desired to establish techniques regarding heat-developable light-sensitive photographic materials for diagnosis and for photographic applications which can be efficiently exposed with a laser image setter or a laser imager to form a crisp black- anf-white image with high resolution and sharpness. Such heat-developable light-sensitive photographic materials will provide customers with a simpler and more environmentally friendly heat development system involving no wet chemical processing.
While there has been the same demand in the field of general image formation, images for diagnosis characteristically demand high quality in sharpness and graininess for precision and a cool black tone for facilitating diagnosis. From this viewpoint, hard copy systems using pigments or dyes which are currently available as general image forming systems, such as ink jet printers and electrophotographic apparatus, are not satisfactory as an output system for medical diagnostic imaging modalities.
Under these circumstances, a dry system recording apparatus involving no wet processing has recently engaged attention. Light- and heat-sensitive materials or heat-developable light-sensitive photographic films (hereinafter inclusively referred to as photothermographic recording materials) are used in such a recording apparatus. In the dry system recording apparatus, a photothermographic recording material is irradiated (scanned) with laser light to form a latent image in an image exposure section, brought into contact with a heating unit to perform heat development in a heat development section, and, after cooled, discharged out of the apparatus. The dry system is able to eliminate the waste liquid disposal problem associated with a wet system.
Thermal image formation systems using organic silver salts are described, e.g., in U.S. Pat. Nos. 3,152,904 and 3,457,075 and “Thermally Processed Silver Systems” by B. Shely in J. Sturge, V. Walworth and A. Shepp (eds.),
Imaging Processes and Materials Noblette's Eighth Edition,
1996, 2. Photothermographic recording materials generally have a light-sensitive layer comprising a catalytic amount of a photocatalyst (e.g., silver halide), a reducing agent, a reducible silver salt (e.g., organic silver salt) and, if needed, a toning agent for controlling the tone of developed silver, all dispersed in a binder matrix. After imagewise exposure, the photothermographic recording material is heated to an elevated temperature (e.g., 80° C. or higher) to induce redox reaction between the silver halide or the reducible silver salt (acting as an oxidizing agent) and the reducing agent thereby to form a black silver image. The redox reaction is accelerated by the catalytic activity of the latent image of silver halide generated on exposure. Therefore, the black silver image is formed in the exposed area. Photothermographic recording materials and systems based on this principle have been disclosed in many documents, such as U.S. Pat. No. 2,910,377 and JP-B-43-4924. Commercially available medical imaging systems using a photothermographic recording material include Fuji Medical Dry Imager FM-DP L supplied by Fuji Medical Systems Inc.
Photothermographic recording materials using an organic silver salt are produced by coating a support with an organic solvent-based coating composition or an aqueous dispersion containing polymer particles as a main binder. Excluding the necessity of extra steps such as solvent recovery, the method using the aqueous dispersion is advantageous for equipment simplicity and suitability to large volume production.
In the above-described heat development systems, image data from an image data supply source are subjected to various image processings, such as sharpness processing and shading correction, to obtain data suited to an image recording method, and an image is recorded on a recording material according to the processed data. The apparatus for image recording is required to always output an image of prescribed density according to the image data sent from various image data supply sources, such as a diagnostic imaging modality and an image reading unit. For example, in an image forming apparatus which receives 10-bit digital data and forms an image according to the data, where 300 digital data correspond to a density of 1.2, the apparatus should always output an image of density 1.2 for 300 digital data.
However, there are variations among individual heat developing apparatus, and the recorded image density also varies depending on the environment in which the apparatus is installed. It is impossible for all the apparatus to output an image of a prescribed density based on a piece of image data supplied. Therefore, density correcting conditions are programmed into a general image recording apparatus so as to output an image having a prescribed density according to image data, whereby the image data are corrected (so-called calibration). Further, because an image recording apparatus changes its condition with the progress of recording or with time, it is difficult to obtain an image of a prescribed density in a stable manner for a long period of time. A laser recording apparatus, for instance, not only suffers from contamination, wear or like changes in its optical system in long-term use but is exposed to environmental changes, particularly in temperature. As a result, the density of the output image based on the same data varies with time. It is therefore necessary to periodically reset the density correcting conditions.
The density correcting conditions are set or reset as follows. A chart for density correction having patches of various densities is outputted from a heat developing apparatus. For example, a density correcting chart
500
shown in
FIG. 5
is used. The chart
500
has 24 monochromatic patches of densities varying from 0 to 23. The density of each patch of the output is measured with a built-in densitometer
600
shown in FIG.
6
. The built-in densitometer
600
basically comprises a light emitter
601
and a light sensor
602
.
In the example shown in
FIG. 6
, a red LED is used as the emitter
601
, and the sensor
602
is adapted to detect transmitted light. The sensor
602
detects light quantity of transmitted light
500
a
through the chart
500
(output) by the photo receptor
602
a
, converts the transmitted light quantity into electrical signals, and outputs the signals to a recording controller
37
(see FIG.
2
).
In the built-in densitometer
600
, the chart
500
is irradiated with a predetermined amount of light
601
a
. The sensor
602
receives light
500
a
transmitted through the chart
500
at the receptor
602
a
and outputs signals corresponding to the amount of detected transmitted light to the recording controller
37
(FIG.
2
). The recording controller
37
processes the signals into densities, compares the densities (measured with the built-in densitometer
600
) with the densities of the images which are to be recorded by the heat developing apparatus (i.e., the image densities corresponding to image data) to draw a calibration curve.
The problem is that built-in densitometers generally employed are designed to measure densities of wet-processed images formed by silver salt color formation. It follows that they fail to stably execute accurate measurements when applied to images formed by dye color formation as in thermo-recording. In detail, commonly us
Fuji Photo Film Co. , Ltd.
Rutledge D.
Sughrue & Mion, PLLC
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