Electrophotography – Control of electrophotography process – Of plural processes
Reexamination Certificate
2001-10-03
2003-07-15
Braun, Fred L. (Department: 2852)
Electrophotography
Control of electrophotography process
Of plural processes
C399S053000
Reexamination Certificate
active
06594453
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to an image-forming device, such as a copying machine utilizing electrophotography, a facsimile, and a printer, and more particularly, to an image-forming device including process regulating means for regulating an image-forming electric potential formed on a latent image on an image-bearing member, and for regulating a toner density of a developer to form a toner image of the latent image, etc.
2. Description of the Related Art
In general, an image-forming device of this type comprises various types of image-forming means, such as a photosensitive member functioning as an image-bearing member, an electrifying device electrifying the photosensitive member, an exposing device forming a latent image on the electrified photosensitive member, a developing device developing the latent image on the photosensitive member so as to form a toner image on the photosensitive member, a transferring device transferring the toner image formed on the photosensitive member to a recording paper functioning as a recording medium, a cleaning device removing a residual toner on the photosensitive member after transferring, and a fixing device fixing the transferred toner image on the recording paper.
Further, in order to form an output image of a targeted quality, the image-forming device of this type conventionally performs various process regulations, such as an image-forming-potential regulation for regulating an image-forming electric potential of the latent image formed on the photosensitive member, and a toner-supplement regulation for adjusting a toner density of the developer used to form the toner image from the latent image.
The above-mentioned toner-supplement regulation is performed, for example, as follows.
First, as shown in FIG.
1
and
FIG. 2
, a plurality (three in the figures) of latent image patterns
20
a
,
20
b
and
20
c
at predetermined electric potentials are formed on a photosensitive member
20
.
Next, an infrared light is projected from a toner-amount detecting sensor
25
to the photosensitive member
20
so as to detect the amount of toner attached on the latent image patterns
20
a
,
20
b
and
20
c.
The toner-amount detecting sensor
25
comprises a light-emitting element
25
a
emitting the infrared light, and a light-receiving element
25
b
receiving a regular reflected light (a light beam having a reflection angle equal to an incident angle) of the infrared light, as shown in FIG.
2
.
The toner-amount detecting sensor
25
detects whether or not the amount of the toner attached on the latent image patterns
20
a
,
20
b
and
20
c
is equal to a targeted amount of toner corresponding to a desired output image, on the basis of a luminous energy of the regular reflected light received by the light-receiving element
25
b
. When the luminous energy of the regular reflected light received by the light-receiving element
25
b
is large, i.e., when the amount of the toner attached on the latent image patterns
20
a
,
20
b
and
20
c
is insufficient, a toner supplement signal is output from the light-receiving element
25
b.
Then, when the toner supplement signal is output from the light-receiving element
25
b
, a proper amount of toner is supplemented from a toner-supplementing device (not shown in the figures) to the above-mentioned developing device. Thereby, the toner density of the developer supplied from the developing device is made appropriate so that the amount of the attached toner of the toner image formed on the photosensitive member
20
becomes an amount that can achieve a targeted quality of the desired output image.
On the other hand, the above-mentioned image-forming-potential regulation is performed, for example, as follows.
First, as shown in
FIG. 3
, a plurality (three in the figure) of patterned latent images at electric potentials different from one another by increasing degrees are formed on the photosensitive member
20
, and are developed by using a toner so that latent image patterns
30
a
,
30
b
and
30
c
having different toner densities are formed on the photosensitive member
20
.
Next, a development characteristic (a development &ggr;) of the above-mentioned developing device is calculated from the relationship between the amount of toner attached on the latent image patterns
30
a
,
30
b
and
30
c
and the surface potential of the latent image patterns
30
a
,
30
b
and
30
c
detected by a potential sensor (not shown in the figure). A grid voltage of the above-mentioned electrifying device, a development bias of the above-mentioned developing device, and an LD (a laser luminescence) power of the above-mentioned exposing device, etc. are regulated so that the amount of the toner attached on the latent image patterns
30
a
,
30
b
and
30
c
becomes equal to a targeted amount of toner. Thereby, the electric potential to form the toner image on the photosensitive member
20
is optimized so that the amount of the attached toner of the toner image becomes an amount that can achieve a targeted quality of a desired output image.
Thus, it is supposed that, in the image-forming device of this type, if the toner density of the developer supplied from the developing device and the electric potential to form the toner image on the photosensitive member
20
are optimized by the above-described toner-supplement regulation and the image-forming-potential regulation, the amount of the attached toner of the toner image is maintained in an ideal condition that can achieve the targeted quality of the desired output image.
In reality, however, the image-forming device of this type performs an image formation in various cases as follows: the toner image is formed only by a developer of a particular color; an image area is extremely small; a normal image formation is hardly performed, and therefore, only an automatic regulation is performed in which the toner supplementation by the above-mentioned image-forming-potential regulation, etc. is not performed. At this point, normally in the above-mentioned toner-supplement regulation, when the toner image is not formed on the photosensitive member
20
, no toner is supplemented from the above-mentioned toner-supplementing device to the above-mentioned developing device. Therefore, when the development capability (a capability of developing the latent image) of the developing device is either higher or lower than a standard level, there occurs a problem that the image-forming potential-regulation alone cannot sufficiently regulate the amount of the attached toner of the toner image.
In order to solve this problem, there is a conventional image-forming device performing a so-called self-check, in which a toner is supplemented to the above-mentioned developing device; or a toner is consumed in the developing device, at a predetermined timing, so as to adjust the toner density of the developer supplied from the developing device, and thereafter, the above-mentioned image-forming-potential regulation is performed.
The image-forming-potential regulation in this image-forming device is performed as a special job at a timing different from an image-forming routine of a normal toner image. For example, the image-forming-potential regulation is performed, for example, immediately after electric power is supplied to the image-forming device having the above-mentioned fixing device in a cool state, after an image-forming job is performed predetermined times, or after a predetermined time has passed since the previous image-forming-potential regulation.
The special job for the self-check as mentioned above is effective in maintaining an image quality. Especially, in a color-image forming device, the process regulations are made more stable by performing various regulations, as described above, based on plenty of information in a sufficient period of time for each color.
However, in an image-forming device structured so as to perform the special job for the self-check as mentioned above, various regulations are perf
Braun Fred L.
Ricoh & Company, Ltd.
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