Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2002-01-31
2004-10-19
Rodee, Christopher (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S045320, C430S110300
Reexamination Certificate
active
06806015
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image forming method using a toner composed of flattened spheroid particles (hereinafter referred to simply as flattened toner) as a toner of a two-component developer or a single-component developer for use in a copying machine, a printer, etc.
An image which is formed by using a toner produced by a usual pulverization method or polymerization method does not become a good glossy image owing to ruggedness produced on the surface resulted from the large amount of toner consumed; therefore, it has been difficult to obtain a high-quality image. Further, in the transfer process, the toner layer becomes thick because of the large amount of toner consumption to make the transfer ratio low; therefore, it has been impossible to obtain a high-density image, and occurrence of toner scattering has been making it impossible to obtain a good image.
Up to now, in order to obtain a printing-like, high-quality image, it has been made the attempt that the amount of toner consumption is made small by making the particle diameter of the toner smaller, to eliminate the ruggedness on the image surface to obtain a uniform gloss; however, because the covering power of the toner was lowered with the particle diameter of the toner being made smaller, a sufficient image density has not been able to be obtained, and because image forming processes such as development, transfer, and cleaning of the photoreceptor became difficult, a high-quality image has not been obtained by an image forming method based on electrophotography. Further, if toner particles having such a small particle diameter as 2 to 3 &mgr;m are used, in the case where an operator inhale the toner particles, there is a risk that he suffers from a disease such as pneumoconiosis; therefore, it is not preferable from the view point of safety and sanitation.
When a color image (having a printed area ratio of 25%) is formed by superposing color toner images by an electrophotographic method using spherical-shaped or indefinite-shaped color toners having a particle diameter of about 5 &mgr;m, which does not cause pneumoconiosis etc., the amount of toner consumption is about 90 mg per print sheet of A-4 size, and a thick toner layer is to be processed in development, transfer, and fixing. For this reason, scattered toner particles are observed in the toner image, and ruggedness is produced on the image surface, to make the difference in gloss between a toner deposition area and the background area; that is, it is the present state of the art that an image having a high image quality cannot be formed.
Further, the present invention relates to an image forming apparatus comprising a fixing device for use in a copying machine, a printer, a FAX machine, etc., and in particular, to an image forming apparatus capable of making fixing performance better by using a flattened toner in the developer.
Because an image formed by an image forming apparatus which forms a toner image on an image forming member using a toner composed of spherical-shaped or indefinite-shaped particles produced by a usual pulverization method or polymerization method, and then transfers the toner image onto a transfer material, to fix it, by an image forming apparatus which superposes toner images on an image forming member to form a color toner image composed of the toner images superposed on the image forming member, and then transfers the toner images all at a time, to fix them, by an image forming apparatus which transfers sequentially onto an intermediate transfer member toner images which have been formed on an image forming member in each of image forming units using a toner having a varied color for each, to form a color toner image composed of the toner images superposed on the intermediate transfer member, and then transfers the toner images on the intermediate transfer member all at a time, to fix them, or by the like, produces ruggedness on the image surface owing to the large amount of toner consumption, it has been difficult to obtain a printing-like image quality. Further, because of a large amount of toner consumption, toner layer became thick to make the transfer ratio low; therefore, a high-density image could not be obtained, and toner scattering occurred to make it impossible to obtain a good image. Especially, this problem became remarkable in the case of a color toner image composed of toner images superposed, and also fixing performance was bad.
In order to solve the above-mentioned problems, the inventors of this application has been attempting to make a toner layer thinner and flat, and in particular, to make a layer of superposed color toners thinner and flat; however, owing to the disturbance of the flattened toner particles in fixing (disturbance of the toner image), if a toner image is fixed under high pressure (Especially for a color toner image composed of toner images superposed, because it has a thick toner layer, the toner disturbance is remarkable, and higher pressure is necessary.), it is posed a problem that toner particles are crushed and spread to produce a disturbance of image, and because it is necessary to broaden the width of the nip portion owing to the spread of toner particle crushing (for a color toner image composed of toner images superposed, it is necessary to make the width of the nip portion broader owing to the layer thickness being made thicker), also it is posed a problem that warm-up time becomes longer.
SUMMARY OF THE INVENTION
The present invention has been proposed in view of the above-mentioned points of problem, and it is its object to provide an image forming method using a toner composed of flattened particles to be used with a carrier in a two-component developer or as a single component developer to make it possible to obtain a high-density image even with a small amount of toner consumption and to make it possible to obtain a high-quality image with little ruggedness and without toner scattering.
(1) It is the first object of the present invention to provide an image forming method in which flattened toner particles are deposited on an image forming member or a transfer member in such a way that the toner layer may be made thinner by taking into account the posture of the toner particles being deposited, and development, transfer, and fixing are performed satisfactorily.
(2) The second object of the present invention is to provide an image forming method in which, as a result of it that attention is paid to it that, by using an external additive of the flattened toner, the state of charge distribution on the flattened toner particles is improved to give a proper amount of fluidity, an external additive having a proper charging property is added to the toner, to make development, transfer, and fixing performed satisfactorily.
(3) The third object of the present invention is to provide an image forming method in which, as a result of it that attention is paid to it that, in adding an external additive to a flattened toner, it is extremely effective to select suitably the relation between the size of toner particles and the particle diameter of the external additive, an external additive having a suitable particle diameter is added to make development, transfer, and fixing performed satisfactorily.
(4) The fourth object of the present invention is to provide an image forming method in which, as a result of it that attention is paid to it that if there is a dispersion not smaller than a certain limit in the size and shape of the flattened toner, a good image cannot be obtained, a flattened toner which has been subjected to a suitable treatment and sorting in the manufacturing process of the toner is used, to make it possible to obtain an image having a high image quality.
(5) The fifth object of the present invention is to provide an image forming method in which, as a result of it that attention is paid to it that if there is a dispersion in the flat shape of the flattened toner, a good image cannot be obtained, the dispersion in the flattening ratio is
Haneda Satoshi
Yamazaki Hiroshi
Konica Corporation
Rodee Christopher
Squire Sanders & Dempsey
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