Electrophotography – Control of electrophotography process – Of plural processes
Reexamination Certificate
2001-03-28
2002-05-21
Brase, Sandra (Department: 2852)
Electrophotography
Control of electrophotography process
Of plural processes
C399S074000
Reexamination Certificate
active
06393228
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a toner amount measuring apparatus for optically measuring the amount of toner adhering onto a photosensitive medium or transfer belt of an image forming apparatus such as a printer, a copying machine, a facsimile machine, etc., and an image forming apparatus equipped with a toner amount measuring unit having the same function as the toner amount measuring apparatus.
2. Description of the Related Art
A measurement of a toner amount on a photosensitive medium or transfer belt of an image forming apparatus such as a printer, a copying machine, a facsimile machine or the like plays an important role in controlling an image forming process in the image forming apparatus. Therefore, a toner amount measuring apparatus which optically measures the amount of toner has been well known, and also an image forming apparatus in which a toner amount measuring unit having the same function as the toner amount measuring apparatus is installed to control the image forming process on the basis of a measurement result. In the following description, a carrier for toner which is represented by a photosensitive medium, a transfer belt, etc. is generically referred to as “image forming body”). Further, in the following description, the terms of the toner amount measuring apparatus and the toner amount measuring unit are used with no discrimination at some places.
Next, the construction of a conventional toner amount measuring apparatus will be described with reference to
FIGS. 1
to
4
.
The image forming bodies such as the photosensitive medium, the transfer belt, etc. to which toner adheres are generally designed to have a mirror surface structure having high flatness, and the toner amount on these image forming bodies has been hitherto measured by utilizing this surface characteristic.
FIG. 1
is a diagram showing the principle of a toner amount measuring apparatus using mirror reflection.
According to the toner amount measuring apparatus using the mirror reflection, light L
1
having a predetermined intensity is emitted from a light source
2
such as a light emitting diode (LED) or the like onto the surface of an image forming body
1
, and mirror-reflected as reflected light L
2
from the surface of the image forming body
1
. The reflected light L
2
is detected by an optical sensor
3
such as a photodiode or the like, and a voltage having the magnitude corresponding to the intensity of the reflected light L
2
thus detected is output from the optical sensor
3
.
The reflected light L
2
is intercepted by toner particle
4
in a toner-adhering area on the surface of the image forming body
1
. Therefore, the light amount of the light L
2
which is reflected from the toner-adhering area on the surface of the image forming body
1
and then detected by the optical sensor
3
is reduced by the amount corresponding to the interception of the light L
2
, and thus the output voltage from the optical sensor
3
is also reduced.
FIG. 2
is a graph showing the relationship between the amount of toner adhering onto the surface of the image forming body
1
and the output voltage of the optical sensor
3
in the toner amount measuring apparatus using the mirror reflection.
The abscissa of the graph of
FIG. 2
represents the amount of toner adhering onto the surface of the image forming body, and the ordinate of the graph of
FIG. 2
represents the output voltage of the optical sensor.
As described above, the output voltage of the optical sensor corresponds to the light amount of the mirror-reflection light from the surface of the image forming body. As indicated by a curved line
5
which is drawn from the upper left-hand side to the lower right-hand side in the graph, the output voltage of the optical sensor is reduced as the toner adhering amount increases. By determining the curved line
5
in advance, the amount of toner adhering to the surface of the image forming body can be calculated on the basis of the relationship indicated by the curved line
5
and the output voltage of the optical sensor.
When color toner (color toner particles) is used, light used for irradiation of the color toner particles is diffused due to reflections of the light from the surfaces and inner parts of the color toner particles. A toner amount measuring apparatus using such diffused light has been known.
FIG. 3
is a diagram showing the principle of the toner amount measuring apparatus using the diffused light as described above.
In the case of the toner amount measuring apparatus using the diffused light, light L
1
having a predetermined intensity is emitted from a light source
2
to the surface of the image forming body
1
as in the case of the toner amount measuring apparatus using the reflected light. However, an optical sensor
6
is disposed at a position out of the travel path of the reflected light L
2
shown in FIG.
1
. The diffused light L
3
caused by the toner particle
4
adhering to the surface of the image forming body
1
is detected by the optical sensor
6
, and the voltage corresponding to the intensity of the diffused light L
3
thus detected is output from the optical sensor
6
.
FIG. 4
is a graph showing the relationship between the toner adhering amount and the output voltage of the optical sensor in the toner amount measuring apparatus using the diffused light.
Like the graph of
FIG. 2
, the abscissa of the graph of
FIG. 4
represents the toner amount, and the ordinate thereof represents the output voltage of the optical sensor. In this case, the output voltage of the optical sensor corresponds to the light amount of the diffused light caused by the toner
4
.
As indicated by a curved line
7
in the graph of
FIG. 4
, the output voltage of the optical sensor increases as the toner adhering amount increases. By determining such a curved line
7
in advance, the amount of toner adhering to the surface of the image forming body can be calculated on the basis of the relationship indicated by the curved line
7
and the output voltage of the optical sensor.
Most of conventional toner amount measuring apparatuses use only one or both of the measuring principles shown in
FIGS. 1 and 3
, and for example Japanese Patent Laid-open No. Hei-6-66722 discloses one of these toner amount measuring apparatuses.
Here, a target for the toner amount measurement will be described.
FIG. 5
shows a target (object) for the toner amount measurement. In the following description, a toner-amount measurement target in an electrophotographic image forming apparatus will be described.
A toner image is formed according to the procedure described below in the electrophotographic image forming apparatus.
First, the surface of a photosensitive roll
8
rotating in the direction indicated by an arrow F of
FIG. 5
is uniformly charged by a bias charging unit
9
, and then the surface of the photosensitive roll
8
is irradiated with a laser beam emitted by a laser exposing unit
10
to form an electrostatic latent image. Subsequently, toner adheres to the electrostatic latent image with a developing unit
11
to form a toner image
12
. The toner image
12
thus formed is transferred onto a transfer belt
14
by a transferring unit
13
to form a transfer image
15
. The transfer image
15
is subsequently transferred to a sheet again, and finally a toner image is formed on the sheet.
The toner image
12
on the photosensitive roll
8
and the transfer image
15
on the transfer belt
14
have been targeted as toner-amount measurement objects, and the amount of toner constituting the toner image
12
and the transfer image
15
is set to about 0.1 to 0.7 mg/cm
2
. The toner amount in this range can be measured with high precision by using the conventional toner amount measuring apparatuses.
In addition to the toner with which the toner image
12
and the transfer image
15
as described above are formed, a minute amount of toner which induces “fog” or “residual toner” as described later is also particularly targeted as an object on a
Brase Sandra
Fuji 'Xerox Co., Ltd.
LandOfFree
Toner amount measuring apparatus and method, and image... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Toner amount measuring apparatus and method, and image..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Toner amount measuring apparatus and method, and image... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2862031