Radiation imagery chemistry: process – composition – or product th – Imaged product – Multilayer
Reexamination Certificate
2000-02-01
2001-08-14
Dote, Janis L. (Department: 1753)
Radiation imagery chemistry: process, composition, or product th
Imaged product
Multilayer
C430S018000, C430S045320, C430S106100, C430S109500, C430S110100, C430S111400
Reexamination Certificate
active
06274282
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image formation method capable of producing a full-color image by superimposing four yellow, magenta, cyan and black toner images in the field of electrophotographic recording, a set of color toners for use in the above-mentioned full-color electrophotographic image formation method, and a color image formed by the above-mentioned full-color image formation method.
2. Discussion of Background
A color copying machine and a color printer employing the electrophotographic process have been widely used in recent years. In the electrophotographic process for producing a color image, there are employed yellow, magenta and cyan toners, optionally a black toner being added thereto when necessary.
The color image is required to have a proper degree of glossiness. To fulfill the above requirement, a binder resin with a relatively low softening point is conventionally used for a color toner so as to make the surface of a toner layer constituting a color image area flat.
The amount of color toner deposited on a transfer sheet by development widely varies in a color image such as a full-color photographic image formed by the electrophotographic method of producing a full-color image. To be more specific, chromatic color images include many portions with the deposition amount of a color toner being small, while a black image is provided with a large amount of a black toner. The conventional full-color image in which the deposition amount of color toner shows some scatter, as mentioned above, has the shortcoming that the glossiness tends to be uneven in the entire image. In addition, the glossiness of the black image portion is extremely high, and the image will become dull as a whole.
The glossiness of the black image portion can be reduced when the black toner comprises as the binder resin the same resin as employed in the monochrome toner or a polymeric resin with a relatively high softening point. In such a case, however, there is the problem that a photographic image including a black image portion, such as a photographic image of a manes face, becomes considerably unattractive. In particular, when a color image includes a character image and a photographic image, both the character image and the photographic image become dull because there is a great difference in glossiness between a highlight portion of the photographic image and the character image portion.
There is a proposal in Japanese Laid-Open Patent Application 8-220821 to solve the problem of uneven glossiness in the full-color image. Namely, full-color images are formed by use of chromatic color toners, that is, yellow, magenta and cyan toners in combination with a transparent toner capable of producing a transparent image with a specified glossiness. This method, however, cannot be applied to the conventional electrophotographic copying machine because the transparent toner is additionally employed.
SUMMARY OF THE INVENTION
Accordingly, a first object of the present invention is to provide an electrophotographic full-color image formation method capable of producing attractive full-color images with even glossiness by reducing the glossiness of a black image portion.
A second object of the present invention is to provide a set of yellow, magenta, cyan and black toners for use with the above-mentioned electrophotographic full-color image formation method.
A third object of the present invention is to provide a color image formed by the above-mentioned electrophotographic full-color image formation method using the above-mentioned set of color toners.
The first object of the present invention can be achieved by an image formation method for forming a color image comprising the step of superimposing four yellow, magenta, cyan and black toner images which are respectively obtained by developing four latent electrostatic images, which respectively correspond to the four yellow, magenta, cyan and black toner images, with a yellow toner, a magenta toner, a cyan toner and a black toner, wherein a gradient a
Y
of a yellow glossiness per unit amount of the yellow toner (mg/cm
2
) deposited on a transfer sheet, a gradient a
M
of a magenta glossiness per unit amount of the magenta toner (mg/cm
2
) deposited on a transfer sheet, and a gradient a
C
of a cyan glossiness per unit amount of the cyan toner (mg/cm
2
) deposited on a transfer sheet are in a range of 0.8 a to 1.2 a, and a gradient a
BK
of a black glossiness per unit amount of the black toner (mg/cm
2
) deposited on a transfer sheet is in a range of 0.4 a to 0.7 a, in which a=(a
Y
+a
M
+a
C
)/3.
The second object of the present invention can be achieved by a set of a yellow toner, a magenta toner, a cyan toner and a black toner, for forming a full-color image by superimposing four yellow, magenta, cyan and black toner images which are respectively obtained by developing four latent electrostatic images, which respectively correspond to the four yellow, magenta, cyan and black toner images, with the yellow toner, the magenta toner, the cyan toner and the black toner, wherein a gradient a
Y
of a yellow glossiness per unit amount of the yellow toner (mg/cm
2
) deposited on a transfer sheet, a gradient a
M
of a magenta glossiness per unit amount of the magenta toner (mg/cm
2
) deposited on a transfer sheet, and a gradient a
C
of a cyan glossiness per unit amount of the cyan toner (mg/cm
2
) deposited on a transfer sheet are in a range of 0.8 a to 1.2 a, and a gradient a
BK
of a black glossiness per unit amount of the black toner (mg/cm
2
) deposited on a transfer sheet is in a range of 0.4 a to 0.7 a, in which a=(a
Y
+a
M
+a
C
)/3.
The third object of the present invention can be achieved by a full-color image formed by superimposing four yellow, magenta, cyan and black toner images which are respectively obtained by developing four latent electrostatic images, which respectively correspond to the four yellow, magenta, cyan and black toner images, with a yellow toner, a magenta toner, a cyan toner and a black toner, wherein a gradient a
Y
of a yellow glossiness per unit amount of the yellow toner (mg/cm
2
) deposited on a transfer sheet, a gradient a
M
of a magenta glossiness per unit amount of the magenta toner (mg/cm
2
) deposited on a transfer sheet, and a gradient a
C
of a cyan glossiness per unit amount of the cyan toner (mg/cm
2
) deposited on a transfer sheet are in a range of 0.8 a to 1.2 a, and a gradient a
BK
of a black glossiness per unit amount of the black toner (mg/cm
2
) deposited on a transfer sheet is in a range of 0.4 a to 0.7 a, in which a=(a
Y
+a
M
+a
C
)/3.
REFERENCES:
patent: 5061588 (1991-10-01), Fushimi et al.
patent: 5126221 (1992-06-01), Chiba et al.
patent: 5840456 (1998-11-01), Tomita et al.
patent: 5840457 (1998-11-01), Urawa et al.
patent: 5879848 (1999-03-01), Kurose et al.
Kuramoto Shin-ichi
Sugimoto Shohichi
Dote Janis L.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Ricoh & Company, Ltd.
LandOfFree
Full-color electrophotographic image formation method, color... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Full-color electrophotographic image formation method, color..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Full-color electrophotographic image formation method, color... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2533431