Image forming method

Details Image forming method Image forming method

2000-07-13

2002-02-19

Chea, Thorl (Department: 1752)

Radiation imagery chemistry: process, composition, or product th

Thermographic process

Heat applied after imaging

C430S363000, C430S380000, C430S383000, C430S385000, C430S391000, C430S505000, C430S604000, C430S944000, C430S945000

Reexamination Certificate

active

06348302

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a method for forming an image, and more particularly to a method for forming an image by subjecting a heat-developable light-sensitive material to exposure to light using a plurality of exposure light sources.
BACKGROUND OF THE INVENTION
Heat-developable light-sensitive material is known in the art, and heat-developable light-sensitive materials and their processes are described, for example, in “Shashin Kogaku no Kiso (Higinen Shashin-hen)” (published by Korona-sha, 1982), pages 242 to 255, and in U.S. Pat. No. 4,500,626.
Further, methods wherein, for example, dye images are formed by the coupling reaction of the oxidized product of a developing agent with a coupler are described, for example, in U.S. Pat. No. 3,761,270 and U.S. Pat. No. 4,021,240. Furthermore, methods for forming a positive color image by the light-sensitive silver dye bleach process are described, for example, in U.S. Pat. No. 4,235,957.
Further, the method wherein a diffusion dye is released or formed imagewise by heat development and the resultant diffusion dye is transferred to a dye-fixing element is proposed. In this method, by changing the type of the dye-providing compound to be used or the type of the silver halide to be used, a negative dye image, as well as a positive dye image, can be obtained. More details are described, for example, in U.S. Pat. No. 4,500,626, U.S. Pat. No. 4,483,914, U.S. Pat. No. 4,503,137, U.S. Pat. No. 4,559,290, JP-A-58-149049 (“JP-A” means unexamined published. Japanese patent application), JP-A-60-133449, JP-A-59-218443, JP-A-61-238056, EP-A-220 746 (A2), the Journal of Technical Disclosure (“Kokai Giho”) 87-6199, EP-A-210 660 (A2).
With respect to the method for obtaining a positive color image by heat development, various methods have been proposed. For example, U.S. Pat. No. 4,559,290 proposes a method wherein a so-called DRR compound, which has been formed into an oxidized compound incapable of releasing a dye image, is used under the coexistence with a reducing agent or a precursor thereof. In this method, the reducing agent is oxidized in proportion to the exposure amount of a silver halide by heat development, and the above oxidized compound is reduced with the unoxidized remaining reducing agent, to cause a diffusion dye to be released, to form a positive color image. Further, EP-A-220 746 (A) and the Journal of Technical Disclosure (“Kokai Giho”) No. 87-6199 (Vol. 12, No. 22) describe heat-developable color light-sensitive materials wherein use is made, as a compound capable of releasing a diffusion dye by the same mechanism, of a compound capable of releasing a diffusion dye by reductive cleavage of the N—X bond, in which X represents an oxygen atom, a nitrogen atom, or a sulfur atom.
Since the heat-developable color light-sensitive material can be processed easily and rapidly in comparison with the conventional wet-development light-sensitive material, development can be conducted by means of a small-sized compact apparatus (devices). Accordingly, relatively inexpensive apparatuses as color printers, or color copies of a silver salt color light-sensitive material system, are being developed and sold. To further broaden the application of these apparatuses, it is considered that various improvements are required. As the exposure light source for these light-sensitive materials, various proposals are made, and as a digital exposure light source, for example, light-emitting diodes (LED), semiconductor lasers (LD), and various fluorescent substances are used.
When using inexpensive LEDs or LDs, one devised method used is that plural elements are placed side by side, to carry out scanning exposure, thereby shortening the time required for exposure. With regard to exposure methods using a multi-beam, there is a report of a patent using an outer drum system, in which a light-sensitive material is wound around a drum, to carry out exposure, since conveyance of the light-sensitive material on a plane is difficult to carry out.
In the exposure using a multi-beam, a multiple exposure effect, different in time interval from other exposure stations (exposure points), is given to the exposure stations at both ends, in the direction of an array of multi-beams from the exposure station adjacent to the focused exposure station. In this exposure method, an exposure head provided with plural beam light sources is used, to obtain a multi-beam, and a method in which the quantity of light of the light source applied to the exposure stations of both ends is compensated in accordance with LUT, is reported in the specification of JP-A-9-218474.
A method in which the number of multiple exposures using a multi-beam is increased, to prevent exposure streaks and to improve temperature dependency of exposure, is described in the specification of U.S. Pat. No. 5,879,864.
Also, a method in which the location of an exposure beam is changed from that in conventional methods, to carry out exposure in a so-called interleave system, thereby reducing a difference in the hysteresis of exposure, is described in IS & T's International Congress on Advances in Non-Impact Printing Technologies (1994) p. 337.
Each of these methods uses an outer drum system, and there is no description concerning small-sized and compact devices in these methods.
There is a description concerning the effect of multiple exposure and overlap of exposure beam in International Publication No. WO 95/31754 and JP-A-4-51043. However, inventions described therein are concerned with the case of exposure using a mono-beam, and nothing in them refers to the problems posed by exposure of a multi-beam.
JP-A-2-18548 reports that a silver halide emulsion is doped with a heavy metal, to thereby decrease variation in the photographic characteristics caused by multiple exposure during scanning exposure. However, nothing in the publication refers to the problems posed by multi-beam exposure.
JP-A-7-234371 reports an image-formation apparatus that restrains unevenness of density, caused by the effect of multiple exposure, by controlling the manner of superposing light beams in scanning exposure using a mono-beam. However, the publication includes nothing referring to the problems posed by multi-beam exposure.
JP-A-4-249244 describes improvement of a developer, as to a method of restraining the deterioration of the photographic characteristics that is caused when a scanning exposure operation with high intensity and short-time superposition is performed. However, the publication does not mention improvement by an exposure method, and also it nowhere refers to the problems posed by multi-beam exposure.
SUMMARY OF THE INVENTION
It is an object of the present invention to eliminate or improve uneven density of exposure, particularly streaks on an image that are caused by a difference in the hysteresis of multiple exposure of light source points at both ends of an exposure head in a scanning exposure-type image-forming method, in which plural exposure light sources, whose exposure time per exposure is 10
−3
seconds or less, are used.
Other and further objects, features, and advantages of the invention will appear more fully from the following description.
DETAILED DESCRIPTION OF THE INVENTION
The above object is attained by the following means (1) to (6).
(1) An image-forming method, using an exposure head having plural beam light sources that correspond to each exposure station and that emit each light with the same wavelength, to expose to light a light-sensitive material, which is provided at least with a light-sensitive silver halide emulsion and a binder on a support; with the method comprising:
arranging M sets of the beam light sources of the exposure head in a sub-scanning direction, perpendicular to a main scanning direction, along which the exposure head itself is moved, at predetermined intervals, and
allowing said light-sensitive material to move in said sub-scanning direction, in steps of a distance of (the length of the exposure head in the aligned direction)/N (N&g

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