Electrophotography – Diagnostics – Consumable
Reexamination Certificate
2002-11-19
2004-08-03
Chen, Sophia S. (Department: 2852)
Electrophotography
Diagnostics
Consumable
C399S049000, C399S260000
Reexamination Certificate
active
06771911
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Patent Application No. 2001-85316, filed Dec. 26, 2001, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for and a method of controlling a supplying amount of toner, and more particularly, to an apparatus for and a method of accurately controlling a mixing rate of toner and a carrier in accordance with an amount of printing data.
2. Description of the Related Art
A conventional image recording apparatus, such as a laser printer, a printer having a LPH (LED Print Head), or a PP (Plain Paper) facsimile uses an electrophotography developing method.
There are two types of developing methods to allow toner to stick to an electrostatic latent image formed on a photosensitive medium: a one ingredient developing method and a two ingredient developing method. The one ingredient developing method uses the toner only as a one ingredient developing agent, and the two ingredient developing method uses mixed toner and a carrier as a two ingredients developing agent. The image recording apparatus using the electrophotography developing method employs the two ingredients developing method. In the two ingredients developing method, the toner and the carrier are mixed in a predetermined proportion to form the two ingredients developing agent and to send the toner to the electrostatic latent image of the photosensitive medium. Hereinafter, the two ingredients developing agent having mixed toner and the carrier in the predetermined proportion will be referred to as a developing agent. The carrier is a medium to cause the toner to stick to the electrostatic latent image of the photosensitive medium. Ferrous ferrite can be used as the carrier.
It is very important to control a toner density to obtain a good quality of a printing image in the two ingredients developing method unlike the one ingredient developing method. While an amount of the toner is controlled because only the toner is used in the one ingredient developing method, each proportion of the toner and the carrier, in other words, the toner density should be controlled in the two ingredient developing method. Hereinafter, the proportion of the toner and the carrier will be referred to as the toner density.
To maintain the quality of the printing image, it is required to control the toner density accurately. The toner density can be controlled to maintain the proportion of the toner and the carrier constantly. Several methods have been used to control the toner density. For example, a method of compensating for the amount of the toner as much as a change of the toner density which is determined using a signal of a toner sensor in a CPU of the image recording apparatus, is used to control the toner density.
FIG. 1
is a block diagram showing a device controlling the toner density. As shown in
FIG. 1
, a controller (CPU)
10
calculates a value for controlling a toner supply motor by detecting a variation of the toner density in accordance with a signal input from a toner sensor
20
and controls a supply amount of the toner by driving a toner supply motor driving unit
40
in response to the toner supply motor controlling value.
The toner supply motor controlling value is calculated at the controller
10
by using a difference between a toner density set-up value set up to improve the printing quality and a toner density detection value actually detected by the toner sensor
20
. The controller
10
calculates the toner supply motor controlling value to meet the set up toner density and controls the supply amount of the toner by driving the toner supply motor driving unit
40
in response to the toner supply motor controlling value. The toner supply motor controlling value can be set up when the toner supply motor driving unit
40
is turned on or a voltage is supplied to the toner supply motor. The toner supply motor controlling value is calculated by an operational constant of the toner density set-up value stored in a memory
30
when the image recording apparatus is manufactured, and by the toner density detection value input from the toner sensor
20
.
FIG. 2
is a flow chart showing a conventional method of controlling the toner density. As shown in
FIG. 2
, the controller
10
reads the operational constant of the toner density set-up value stored in the memory
30
and a toner controlling value in operation S
10
. Then, the controller
10
reads the toner density detection value in operation S
20
, and calculates a difference ‘e’ between the toner density set-up value read in the operation S
10
and the toner density detection value read in the operation S
20
in operation S
30
. Next, the controller
10
calculates the toner supply motor controlling value ‘U’ by using the operational constant read in the operation S
10
and the difference ‘e’ of the toner density set-up value and the toner density detection value calculated in the operation S
30
in operation S
40
. The controller
10
drives the toner supply motor according to the toner supply motor controlling value ‘U’ in operation S
50
. Each of the above operations S
30
, S
40
, S
50
is repeated (see operation S
60
) after returning to the operation S
20
until a printing operation is completed. The above conventional method controls the toner density by considering only the toner density detection value of the toner sensor and the operational constant.
The toner density should be changed in accordance with a consumed amount of the toner for a predetermined duration, and the consumed amount of the toner should be changed in accordance with printing information (data) about the printing image. When the printing information is a 5% coverage of a sheet of paper, a ratio of the number of dots of the printing information and the number of the entire dots that is printable on one page of the sheet is approximately 5%. Therefore, when the printing information is the 5% coverage, it can be said that the amount of the toner used for printing the printing image on the page of the sheet is approximately 5%. When the printing information is a 100% coverage, the page of the sheet would be printed all black. When a high density background color is used in the printing information, the printing coverage would be 50 to 70%.
In a printing operation for a printing object that requires relatively less printing coverage, there is a narrow difference between the toner density set-up value and the toner density detection value due to relatively small consumption of the toner. For a printing object that requires a wide printing coverage, however, the difference between the toner density set-up value and the toner density detection value becomes wider. For example, when documents including a small amount of letters and documents including a dark colored photograph are printed in turn, a variation of the printing coverage becomes greater. As the variation of the printing coverage increases, there is a great change in the toner supply. Further, if the supply amount of the toner increases more than the toner density set-up value, the toner is scattered. There is a wide difference in the toner consumption per unit time between a case where the toner consumption is 5% and another case where the printing object has a density almost black. Accordingly, there needs to be control of the printing operation of compensating for the difference.
However, the conventional toner density controlling apparatus and method uses a regular operational constant stored in the memory when calculating the toner supply motor (amount) controlling value. In other words, the toner supply motor controlling value is decided by considering only the toner density detection value detected by the toner sensor to the change of the consumed amount of the toner. Therefore, a period of time is required to adjust to the toner density set-up value, and there is a difficulty in controlling the toner
Chen Sophia S.
Samsung Electronics Co,. Ltd.
Staas & Halsey , LLP
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