Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Reexamination Certificate
2002-06-04
2004-11-23
Chapman, Mark A. (Department: 1756)
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
C430S137180
Reexamination Certificate
active
06821696
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toner used in a copier or a printer performing image formation by a form of electrophotography or ionography, and to an image formation apparatus employing the toner. In particular, the present invention relates to a color toner for optical fixing containing a novel infrared light absorbent which absorbs optical energy and converts it into heat, and is fixed onto a recording medium such as a recording paper through optical irradiation thereof, and an image formation apparatus employing this toner.
Moreover, in other words, the present invention relates to a toner by which possible disorder of the color tone of the toner occurring as a result of the toner containing an infrared light absorbent as a component thereof is controlled, and a bright color tone also can be obtained even for a hue which is easy to be influenced of muddiness, such as lemon yellow, and an image formation apparatus employing this toner.
2. Description of the Related Art
As an image formation apparatus which performs printing of documents, copying, etc. in an office etc., one which employs electrophotography or ionography as a drawing principle is used regularly.
In an electrophotographic system, a uniform electrostatic charge is given on a photoconductive insulator (photosensitive drum, etc.), and an electrostatic latent image is formed by applying an optical image on the photoconductive insulator by any of various methods. Subsequently, development of this electrostatic latent image is carried out so as to visualize it using fine powders called toner, then, after transferring the thus-obtained toner powder image onto a recording medium, such as a paper, it is fixed thereonto, and, thus, a printed image is obtained.
On the other hand, in an ionographic system, ion (charged particle) is generated by an ion generating unit, using a carrying drum which has an electrostatic coating as a dielectric member for carrying electrostatic charge, by using the ion, an electrostatic charge image is formed on the surface of the dielectric member. Then, the thus-formed electrostatic charge image is developed by a toner, and a printed image is obtained through processes of transferring and fixing like those of the above-mentioned electrophotographic system.
For the above-mentioned two image forming systems, the fixing process is approximately the same therebetween. A toner powder image formed on the recording medium is fused by pressurization, heating, solvent steam, light, etc., and thus, adheres/is fixed onto the recording medium.
Recently, for the fixing process, an optical fixing form by which a powerful light is applied at a toner powder image and fuses the toner attracts attention by the following reasons:
(1) Since this is non-contacting fixing, blurring of an image, dust, etc. do not occur in the fixing process, and the resolution is not degraded.
(2) There is no waiting time after turning on of a power supply in the apparatus, and, thus, a quick start is possible.
(3) Since an exothermic unit, such as a heating roller, is not used, even if a recording paper is blocked in the fixing assembly by the system failure, there is no problem of ignition.
(4) Even for paper with paste, pre-printed paper, paper having different thickness, and so forth, it is possible to perform the fixing process regardless of such quality of the material and thickness of recording medium.
Currently, for this optical fixing system, the most general method is a flash fixing method which uses a xenon flash lamp for the light source therefor.
Process in which a toner is fixed to a recording paper in the above-mentioned flash fixing method will now be described. A toner (powder) image is transferred from a photosensitive drum etc. onto a recording medium (simply referred to as a recording paper, hereinafter). At this time, as the toner merely adheres to the recording paper in a form of a powder image, when it is rubbed by a finger, for example, the image is easily destroyed.
When flash light (glint of light), such as a xenon flash, is applied to this toner powder image, the toner absorbs the optical energy of the glint of light, this increases in temperature and softens, and thereby, sticks to the recording paper. Then, when the temperature is lowered after the glint-of-light application, the toner image solidifies, and, thus, a fixed image is obtained. It is important to prevent so-called poor fixing performance which causes degradation of quality of the image as a result of the once fixed image being exfoliating from the recording paper when it is bent, or rubbed.
In order to prevent such a situation, the toner used in the optical fixing should satisfy at least the following conditions simultaneously:
(1) The capability of the toner is improved so that the toner absorbs a sufficient quantity of heat.
(2) The toner should fuse promptly by absorbing heat, and permeates a recording paper.
(3) After being cooled, the toner should adhere to the recording paper firmly.
Moreover, as shown in
FIG. 1
, a xenon flash lamp generally used by the optical fixing method has a luminescence distribution through a wider range from ultraviolet to infrared wavelength zones. Especially, this has a strong luminescence intensity, in a near-infrared zone of 800 through 1050 nm. In order to achieve a toner having superior fixing performance, establishment of technology, i.e., technology of using optical energy of this near-infrared zone efficiently, that is, effectively reduction of necessary optical energy to be used, is also needed.
A demand for color printing is increasing especially in recent years. Although a colorant used for a color toner absorbs light in part of a visible light wavelength zone, the light absorbing efficiency for a near-infrared wavelength zone is low. That is, the colorant used for a color toner has a characteristic of being hardly absorbing thermal energy from applied light, and, thus, the toner needs a large energy to be applied for fusion thereof.
Therefore, to put into practice a color toner by which satisfactory fixing performance/characteristic is obtained while the necessary energy can be reduced in the optical fixing system is demanded.
Moreover, with regard to a black toner, while a black color agent which is a colorant absorbs all light of the visible light zone, it also absorbs light of the near-infrared zone relatively well. Therefore, it has been already put in practical use in an electronic photography apparatus which employs the optical fixing system. However, in order to cope with an increasing demand for saving energy in recent years, reduction of the necessary optical energy to be applied is demanded. Thereby, further improvement of light absorbing efficiency of the black toner is demanded.
For the above-mentioned demand, various proposals have been given by Japanese Laid-Open Patent Applications Nos. 58-102247, 60-57858, 7-191492, 10-39535 and 11-65167, Japanese Patent Publication No. 7-23965, Japanese Patent No. 3011936, Japanese Laid-Open Patent Applications Nos. 2000-147824, 2000-214626, etc. By these proposals, technology which heightens flash light absorbing capability as a result of a toner containing as an infrared light absorbent, an amide compound which has a light absorbing capability for a near-infrared zone such as for example, aminium salts, a thiol nickel family complex, an indium oxide family metal oxide, a tin oxide family metal oxide, a zinc oxide family metal oxide, tin acid cadmium, a phthalocyanine and/or naphthalocyanine family compound, a merocyanine pigment, a polymethine pigment, a specific amide compound, etc.
Among the above-mentioned compounds, aminium salts, thiol nickel family complex, phthalocyanine and/or naphthalocyanine family compound and so forth are relatively excellent in performance balance as an infrared light absorbent to be added to a toner for the optical fixing process.
However, aminium salts have the problems as mentioned in the following items (1) and (3), and, also, the thiol nickel family
Ebisu Katsuji
Fukuda Makoto
Ishimaru Seijiro
Katagiri Yoshimichi
Kumagae Yojiro
Chapman Mark A.
Fuji 'Xerox Co., Ltd.
Westerman Hattori Daniels & Adrian LLP
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