Electrophotography – Image formation – Transfer
Reexamination Certificate
1999-04-26
2001-01-16
Chen, Sophia S. (Department: 2852)
Electrophotography
Image formation
Transfer
C219S619000, C399S329000
Reexamination Certificate
active
06175713
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image recording apparatus in which a latent image is formed on an image holding material, a toner is selectively adhered to this to make a visible image, and then, it is transferred and fixed onto a recording member such as a sheet, and specifically to an image recording apparatus such as an electrophotographic recording apparatus, an electrostatic recording apparatus, an ionography, and an apparatus for forming an image using a magnetic latent image.
2. Description of the Related Art
Hitherto, as an image recording apparatus for reproducing an image signal or the like on a recording member such as a sheet, various systems of apparatuses have been put to practical use. For example, there is an apparatus in which a latent image is formed on an image holding material such as a photosensitive drum, a toner is selectively adhered to this to make a visible image, and this toner image is directly transferred to a recording member. There is also an apparatus in which a toner image is temporarily transferred onto an intermediate transfer material, and then, it is transferred onto a recording member.
The system in which an intermediate transfer material is used and a toner image is temporarily transferred onto this, is frequently applied to an apparatus for forming a color image. Toner images of multiple colors are superimposed and transferred onto the intermediate transfer material to form a full-color toner image, and this can be collectively transferred onto a recording member. Such a system has merits that mixture of toners of different colors stored in a developing unit can be prevented, and a full-color image can be formed in a short time by making a so-called tandem apparatus in which multiple image holding materials are provided. Moreover, in the image recording apparatus using the intermediate transfer material, when a toner is transferred from the intermediate transfer material onto the recording member, the toner is heated and melted, and the softened toner is pressed against the recording member, so that transfer and fixing can be carried out at the same time. That is, in the case where transfer is directly carried out to a recording member from an image holding material with a peripheral surface on which a toner image is formed, when the toner is heated and melted, a photosensitive material layer frequently used in the image holding material is also heated, so that its characteristics are changed and excellent image formation becomes impossible. However, when a toner image is temporarily transferred onto the intermediate transfer material and is further transferred onto the recording member, the influence of temperature upon the image holding material can be reduced, and the transfer and fixing can be carried out at the same time.
Incidentally, if an image holding material is not easily influenced by temperature as in ionography, the method in which a toner image is heated so that transfer and fixing are carried out at the same time, can also be used in the case where the image is directly transferred from the image holding material to a recording member.
There have been proposed some image recording apparatuses using the intermediate transfer material in which when a toner image is transferred from the intermediate transfer material onto the recording member, the toner image is heated so that transfer and fixing are carried out at the same time. Such an apparatus is disclosed in, for example, Japanese Patent Unexamined Publication No. Hei. 2-106774, No. Sho. 49-78559, No. Sho. 50-107936, and No. Sho. 57-163264, and Japanese Patent Publication No. Sho. 64-1027.
In the technique disclosed in Japanese Patent Unexamined Publication No. Hei. 2-106774, a recording member is heated prior to transfer of a toner image onto an intermediate transfer material, and the toner on the intermediate transfer material is melted by the heat of the recording member, and is transferred and fixed onto the recording member.
In the techniques disclosed in Japanese Patent Unexamined Publication No. Sho. 49-78559 and No. Sho. 50-107936, a recording member is not heated, but a toner on an intermediate transfer material is heated by a radiation heating means up to its melting temperature, and the intermediate transfer material and the toner image softened on this are pressed against the recording member, so that transfer and fixing are carried out.
In the technique disclosed in Japanese Patent Unexamined Publication No. Sho. 57-163264, an intermediate transfer material and a toner image transferred thereto are previously heated, and in a state where a recording member is heated, both are pressed against each other, so that the toner image is transferred and fixed onto the recording member.
In the technique disclosed in Japanese Patent Publication No. Sho. 64-1027, toner is preliminarily heated before a nip portion (transfer and fixing region) where a toner image on an intermediate transfer material is pressed against a recording member. That is, a belt-like intermediate transfer material is wound around a heating roller at 90° or more, and the toner is preliminarily heated before the nip portion by using the heat of the heating roller, so that the temperature is raised up to the vicinity of the melting temperature of the toner. Thereafter, the toner is further heated and melted at the nip portion, and the toner image is transferred and fixed onto the recording member.
However, the foregoing conventional techniques have problems described below.
The technique disclosed in Japanese Patent Unexamined Publication No. Hei. 2-106774 is preferable since the recording member is heated so that temperature rise of the intermediate transfer material is low and a bad thermal influence upon the image holding material is little. However, utilization efficiency of heat is low, and a large amount of heat energy is consumed for heating of the recording member. Especially in the case where image formation is carried out at high speed, it is necessary to increase the output of a unit for heating the recording member, so that the consumed electric power of the entire apparatus is increased. Besides, when interruption of conveyance of the recording member, a so-called jam occurs, since the recording member (generally, a PPC sheet) is heated to a high temperature, there is also a defect that the danger of firing is high.
The techniques disclosed in Japanese Patent Unexamined Publication No. Sho. 49-78559 and No. Sho. 50-107936 use a radiation heating system as means for selectively heating the toner, so that substantial thermal efficiency becomes low as compared with the heating means using thermal conduction such as a heating roller.
Since the technique disclosed in Japanese Patent Unexamined Publication No. Sho. 57-163264 heats any of the intermediate transfer material, the toner, and the recording member, there is a merit that the temperature of the intermediate transfer material can be set low. Besides, heat conduction between the toner image on the intermediate transfer material and the recording member at the press contact portion is low, and lowering of fluidity of the toner is lessened, so that the toner is sufficiently permeated into the recording member and is transferred from the intermediate transfer material. However, the temperature of the toner at the time when it is separated from the intermediate transfer material is higher than the toner softening point temperature, and the toner is in a fluid state, so that there is a tendency that the toner is divided and is apt to be offset to the side of the intermediate transfer material. Moreover, since any of the intermediate transfer material, the toner, and the recording member are heated, the consumed energy becomes high. Moreover, there is a problem that heat is conducted to the image holding material side by the circular movement of the intermediate transfer material heated by the heating roller, so that the temperature of the periphery of the image holding material is
Kanesawa Yoshio
Kusumoto Yasuhiro
Uehara Yasuhiro
Chen Sophia S.
Fuji 'Xerox Co., Ltd.
Ngo Hoang
Oliff & Berridge
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