Electrophotography – Diagnostics – Consumable
Reexamination Certificate
2001-09-14
2003-12-23
Ngo, Hoang (Department: 2852)
Electrophotography
Diagnostics
Consumable
C399S061000
Reexamination Certificate
active
06668141
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to an image forming apparatus using the electrophotographic process, a cartridge detachably attachable to this image forming apparatus, i.e., a process cartridge, and a developing apparatus made into a cartridge, and particularly to an image forming apparatus, a cartridge and an image forming system in which the remaining amount of developer is detected by the use of storing means carried on the cartridge.
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) and an electrophotographic facsimile apparatus.
The cartridge detachably attachable to the main body of the electrophotographic image forming apparatus refers to one having at least one of an electrophotographic photosensitive body, charging means for charging the electrophotographic photosensitive body, developing means for supplying a developer to the electrophotographic photosensitive body, and cleaning means for cleaning the electrophotographic photosensitive body.
Particularly, the process cartridge refers to at least one of charging means, developing means and cleaning means and an electrophotographic photosensitive body integrally made into a cartridge which is made detachably attachable to the main body of the electrophotographic image forming apparatus, or at least developing means and an electrophotographic photosensitive body integrally made into a cartridge which is made detachably attachable to the main body of the electrophotographic image forming apparatus.
2. Related Background Art
In an image forming apparatus of the electrophotographic type such as an electrophotographic copier or a laser beam printer, light corresponding to image information is applied to an electrophotographic photosensitive body to thereby form a latent image thereon, and a developer is supplied to this latent image by the use of developing means to thereby visualize the latent image, and further the image is transferred from the photosensitive body to a recording medium to thereby form an image on the recording medium. A developer containing container is connected to the developing means, and the developer is consumed by the image being formed.
In such image forming apparatuses, with a view to achieving the simplicity of the interchange and maintenance of such expendibles as an electrophotographic photosensitive body and a developer, there is a process cartridge system in which the electrophotographic photosensitive body, developing means, charging means and cleaning means as process means for acting on the electrophotographic photosensitive body and further, a developer containing container, a waste developer container, etc. are made integral as a process cartridge, which is made detachably attachable to the main body of the image forming apparatus. According to this process cartridge system, the maintenance of the apparatus can be done by a user himself without resorting to a serviceman and therefore, operability can be markedly improved. So, this process cartridge system is widely used in the electrophotographic image forming apparatuses.
Also, as a color image forming apparatus having, for example, developing means of a plurality of colors, there is one in which each developing means and a developer containing container are made into a cartridge which is made detachably attachable to the image forming apparatus and individually interchangeable.
In these image forming apparatuses of the cartridge type, the user can interchange the cartridge, for example, at a point of time whereat the developer has run short, to thereby form an image again. Therefore, in some cases, such an image forming apparatus is provided with means for detecting the consumption of the developer and informing the user of it, i.e., a developer amount detecting apparatus.
The developer amount detecting apparatus has in the cartridge or the main body of the image forming apparatus developer remaining amount detecting means capable of detecting the developer remaining amount level in order to enable the user to know at any time how much of the developer usable for image formation remains in the cartridge. Particularly, if the user can be informed not only of the fact that the developer has run short, but also of the amount of developer as it is sequentially detected, the convenience to the user can be further improved.
As this developer remaining amount detecting means, there is a capacitance measuring system provided with at least one pair of input side and output side electrodes, and measuring the capacitance between the two electrodes to thereby detect the amount of developer. As such a system, there is a plate antenna system. This plate antenna system utilizes a structure such that when there is adopted, for example, a developing method of applying an AC bias to a developer carrying member provided in the developing means to thereby develop a latent image formed on an electrophotographic photosensitive body, a metal plate or plates are provided at a location opposed to the developer carrying member or a plurality of other locations, and a capacitance between the metal plate and the developer carrying member and between these metal plates changes in conformity with the amount of the developer which is an insulative toner or the like.
That is, if the space between the metal plate and the developer carrying member or between the metal plates is filled with the developer, the capacitance therebetween becomes great, and as the developer decreases, the rate at which air occupies the space between the two increases, and the capacitance becomes smaller. Accordingly, by relating in advance the relation between the capacitance between the metal plate and the developer carrying member or the capacitance between the metal plates as a table, the developer amount level can be detected by measuring the capacitance. The measurement of the capacitance can be accomplished by measuring, when an AC bias is applied to the developer carrying member and the metal plate which is an electrode, an electric current flowing through the other metal plate. That is, in the developer remaining amount detecting means of this type, the developer amount is often detected during image formation during which a developing bias is applied to the developer carrying member.
However, even if as described above, provision is made of the developer remaining amount detecting means capable of detecting the developer remaining amount level, there may arise the problem that if use is made of a process cartridge in which, for example, the disposition of the metal plate which is an electrode, or the amount of the developer in the cartridge during the non-use thereof (developer capacity) differs, when the developer remaining amount level is detected by only a preset table, it widely differs from the developer amount actually remaining in the developing apparatus.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an image forming apparatus, a cartridge and an image forming system in which for a cartridge usable in the image forming apparatus, the developer amount can always be detected highly accurately and the user can be informed of an accurate developer amount and an appropriate cartridge interchange time, whereby good images can always be formed.
According to another embodiment of the present invention, there are provided an image forming apparatus, a cartridge and an image forming system in which for a plurality of kinds of cartridges usable in the image forming apparatus and differing, for example, in developer capacity or the like from one another, the developer amount can always be detected highly accurately and the unevenness of the result of the detection of the developer amount due to the individual difference of the cartridges or the image forming apparatus can be prevented.
The above object is achieved by the image forming apparatus, the cart
Kojima Katsuhiro
Matsumoto Hideki
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