Electricity: motive power systems – Plural – diverse or diversely controlled electric motors
Reexamination Certificate
2002-01-30
2004-04-20
Nappi, Robert (Department: 2837)
Electricity: motive power systems
Plural, diverse or diversely controlled electric motors
C318S053000, C318S067000
Reexamination Certificate
active
06724161
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus, and particularly to an improvement of a drive system of a color image forming apparatus.
By using a plurality of image forming elements and an intermediate transfer element, in a color image forming apparatus in which a single color toner image formed on the plurality of image forming elements is transferred onto the intermediate transfer element and one full color image is formed, the drive control of the plurality of image forming elements, the control of time of image formation onto the each of image forming elements and the drive control of the intermediate transfer element are very important. When the consistency is insufficient between the respective controls, or there is a difference of peripheral speed between each of image forming elements or between the image forming element and intermediate transfer element, or the time of toner image formation to each of image forming elements is out of the regular time, a color doubling or image disturbance is generated. Therefore, the high accurate control technology is used for each control.
Relating to the start stop control of each image forming element and the start stop control of the intermediate transfer element, the time control is conducted, and for the image forming element and the intermediate transfer element which are in contact with each other, the time control which starts simultaneously and stops simultaneously is conducted.
However, when the control by only the time is conducted, it has been seen that there are following problems.
It is inevitable that, between the image forming element and the intermediate transfer element, the difference of the rising characteristic and the falling characteristic is generated due to the difference of masses of themselves or the difference of inertia of these drive systems. Accordingly, the velocity change at the rising time of the image forming element and the velocity change at the rising time of the intermediate transfer element are different, and these velocity changes at the falling time are different.
Therefore, even when the image forming element drive motor and the intermediate transfer element drive motor are simultaneously turned on, the image forming element and the intermediate transfer element reach a predetermined steady state velocity through respectively different changes of velocity. Such different rising characteristics are shown in FIG.
1
. It is defined that the image forming element shows the rising characteristic by a curve A, and the intermediate transfer element has the rising characteristic shown by a curve B. Both are operated at the same steady state velocity V, and in an area a, the peripheral speed of the image forming element is larger than the peripheral speed of the intermediate transfer element, and in an area b, the peripheral speed of the intermediate transfer element is larger than the peripheral speed of the image forming element. Because the image forming element and the intermediate transfer element are in contact with each other, when there is the difference between such the rising characteristics, in the area a, the intermediate transfer element and its drive system act as a load on the image forming element drive motor, and in the area b, the image forming element and its drive system act as a load on the intermediate transfer element dive motor.
Such the reverse rotation phenomenon between the peripheral speed of the image forming element and the peripheral speed of the intermediate transfer element or the phenomenon that one side peripheral speed is largely higher than the peripheral speed of the other one, is generated, and an undesirable phenomenon that an excessive load torque is burdened on the drive motor is generated. The phenomenon shown in
FIG. 1
is generated not only at the start time, but also at the time of a steady state operation and stop.
Accordingly, when the design work of the drive system of the image forming element and the drive system of the intermediate transfer element is conducted, it is necessary that the power of the drive motor and the drive current of the motor are set considering not only original loads but also the above described excessive loads.
Therefore, the motor having the excessive power becomes necessary, and the excessive electric power is necessary, resulting in an increase of cost and increase of the power consumption.
SUMMARY OF THE INVENTION
To overcome the abovementioned drawbacks in conventional color image forming apparatus employing the intermediate transfer element, it is an object of the present invention to provide a color image-forming apparatus whose cost is low and power consumption is small.
Accordingly, to overcome the cited shortcomings, the abovementioned object of the present invention can be attained by image-forming apparatus and methods described as follow.
(1) An image-forming apparatus, comprising: a plurality of image-forming elements; a plurality of first driving motors, each of which corresponds to each of the image-forming elements, to drive the plurality of image-forming elements; an intermediate transfer element that is disposed opposite the plurality of image-forming elements; a second driving motor to drive the intermediate transfer element; and a controlling section to control the plurality of first driving motors and the second driving motor; wherein the controlling section controls the plurality of first driving motors and the second driving motor independently of each other, so that a first peripheral speed of each of the image-forming elements coincides with a second peripheral speed of the intermediate transfer element.
(2) The image-forming apparatus of item 1, wherein the controlling section performs controlling actions at a rise time of both the plurality of first driving motors and the second driving motor.
(3) The image-forming apparatus of item 1, wherein the controlling section performs controlling actions at a steady-state operating time of both the plurality of first driving motors and the second driving motor.
(4) The image-forming apparatus of item 1, wherein the controlling section performs controlling actions at a rise time of both the plurality of first driving motors and the second driving motor, so that a moving distance of each of the image-forming elements coincides with that of the intermediate transfer element.
(5) The image-forming apparatus of item 1, wherein, when stopping the plurality of first driving motors and the second driving motor, the controlling section turns off the second driving motor preceding to turning off the plurality of first driving motors.
(6) The image-forming apparatus of item 1, wherein either a stepping motor or a DC motor is employed for both the plurality of first driving motors and the second driving motor.
(7) An image-forming apparatus, comprising: a plurality of image-forming elements; a plurality of first driving motors, each of which corresponds to each of the image-forming elements, to drive the plurality of image-forming elements; an intermediate transfer element that is disposed opposite the plurality of image-forming elements; a second driving motor to drive the intermediate transfer element; and a controlling section to control the plurality of first driving motors and the second driving motor; wherein the controlling section controls the plurality of first driving motors and the second driving motor independently of each other, so that a first peripheral speed of each of the image-forming elements is faster than a second peripheral speed of the intermediate transfer element by a predetermined value.
(8) The image-forming apparatus of item 7, wherein the controlling section performs controlling actions at a rise time of both the plurality of first driving motors and the second driving motor.
(9) The image-forming apparatus of item 7, wherein the controlling section performs controlling actions at a steady-state operating time of both the plurality of first driving motors and the second driving motor.
(10) The
Izumiya Kenji
Kishi Shinobu
Maruyama Hiroyuki
Nishikawa Eiji
Ogata Satoshi
Frishauf Holtz Goodman & Chick P.C.
Konica Corporation
Miller Patrick L
Nappi Robert
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