Electrophotography – Diagnostics – Consumable
Reexamination Certificate
2001-10-18
2003-09-02
Grainger, Quana M. (Department: 2852)
Electrophotography
Diagnostics
Consumable
C399S061000
Reexamination Certificate
active
06615001
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an image forming apparatus using the electrophotographic process, and a process cartridge detachably mountable to the main body of the image forming apparatus or a developing device made into a cartridge, and particularly to an image forming system comprised of storing means carried on the process cartridge or the developing device, and indicating means for detecting the remaining amount of developer by the use of developer amount detecting means disposed in the process cartridge or the developing device, and indicating the result thereof.
The term “electrophotographic image forming apparatus” covers, for example, an electrophotographic copier, an electrophotographic printer (such as an LED printer or a laser beam printer), an electrophotographic facsimile apparatus, etc.
Also, the cartridge detachably mountable to the main body of the electrophotographic image forming apparatus refers to at least one of an electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, developing means for supplying a developer to the electrophotographic photosensitive member, and cleaning means for cleaning the electrophotographic photosensitive member constructed detachably mountably to the main body of the electrophotographic image forming apparatus. Particularly, the process cartridge refers to at least one of the charging means, the developing means and the cleaning means and the electrophotographic photosensitive member constructed integrally with each other, and made detachably mountable to the main body of the electrophotographic image forming apparatus.
2. Related Background Art
An image forming apparatus of the electrophotographic type such as a copier or a laser beam printer applies light modulated in accordance with image information to a photosensitive member to thereby form a latent image thereon, supplies a developer (toner) which is a developing material to the latent image by developing means to thereby visualize the latent image, and further transfers the image from the photosensitive member to a recording medium to thereby form an image on the recording medium. A developer container containing the developer therein is connected to the developing means, and the developer is consumed by images being formed.
In such an image forming apparatus, there is a process cartridge system in which with a view to achieve the simplicity of the interchange and maintenance of expendibles such as the electrophotographic photosensitive member and the developer, the electrophotographic photosensitive member, and developing means, charging means and cleaning means as process means for acting on the electrophotographic photosensitive member, and further a developer container, a developer reservoir or the like are made integral with one another as a process cartridge which is detachably mountable to the main body of the image forming apparatus. According to the process cartridge system, the maintenance of the apparatus can be done by the user himself without resorting to a serviceman and therefore, the operability of the apparatus can be markedly improved. So, the process cartridge system is widely used in electrophotographic image forming apparatus.
Also, for example, among color image forming apparatuses having developing means of a plurality of colors, there is one in which when the degrees of consumption of the respective developing means differ from one another, a developing cartridge of each color into which the developing means of each color and a developer container are made is made detachably mountable to the image forming apparatus so as to be individually interchangeable.
In the image forming apparatus of such a cartridge type, the user can interchange the cartridge, for example, at a point of time whereat the developer has become exhausted, to thereby form an image again. Therefore, such an image forming apparatus is sometimes provided with means for detecting that the developer has been consumed, and informing the user of it, i.e., a developer amount detecting device.
The developer amount detecting device is provided with developer amount detecting means capable of detecting the developer-remaining-amount level in the cartridge or the main body of the image forming apparatus in order to enable how much developer usable for image formation remains in the cartridge to be known at any time.
Particularly, there are image forming apparatuses in which not only the user is informed that the developer has become exhausted, but also the amount of the developer is sequentially detected and the user is informed of it, whereby the convenience to the user is further improved. Among such image forming apparatuses, there is one in which how many percent of the amount when unused the developer remains is calculated and sequentially reported to the user or the “no developer” indication showing that the developer has been decreased to such a degree that image formation of a predetermined quality cannot be effected is done to thereby warn the user that the remaining amount of the developer has become small before a bad image occurs.
As a system of the developer amount detecting means, there is a flat antenna system. A flat antenna is a pattern provided with a pair of electrically conducting portions formed in parallel to each other at a predetermined interval, and disposed at a position on the side of a developer container which is in contact with the developer, and utilizes the fact that the capacitance is changed by the presence or absence of the developer on the surface of the pattern.
The flat antenna is disposed so that as the developer in the developer container is decreased, the area of contact between the developer and the flat antenna may decrease, whereby it becomes possible to make the remaining amount of the developer and the capacitance of the flat antenna correspond to each other, and by measuring the capacitance of the flat antenna, it is possible to know the remaining amount of the developer in the developer container at any time. The capacitance of the flat antenna can be known by a constant AC bias being applied to one of the pair of electrically conducting portions, and from an electric current flowing through the other electrically conducting portion at that time.
Actually, even if the developer in the developer container is gradually decreased, a slight amount of developer adheres to and remains on the flat antenna and in order to remove it, an antenna cleaning member is provided and the surface of the flat antenna is cleaned with the rotation of agitating means.
However, by the cleaning of the surface of the antenna, the output of the flat antenna is fluctuated at a surface cleaning cycle period. So, such statistical processing as taking the mean value in conformity with the cycle period or selecting a minimum value is carried out to thereby decide upon the developer-remaining-amount level.
Also, as another system of the developer amount detecting means, there is developer amount detecting means of the plate antenna type in a developing system wherein an AC bias is applied to a developer bearing member disposed in opposed relationship with a photosensitive member to thereby develop a latent image on the photosensitive member.
The plate antenna is constituted by a metal plate provided in parallel to the developer carrying member, and utilizes the fact that the capacitance between the plate antenna and the developer bearing member changes in conformity with the amount of non-conductive developer present between the two.
If the space between the plate antenna and the developer bearing member is filled up with the developer, the capacitance becomes greater, and as the developer is decreased, the air increases between the two and the capacitance becomes smaller. Accordingly, by predetermining the relation between the capacitance between the plate antenna and the developer bearing member and the amount of developer, to thereby measure the capacitance, th
Hibi Takashi
Otomo Yasunao
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Grainger Quana M.
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