Electrophotography – Internal machine environment – Forced air circulation
Reexamination Certificate
1999-12-20
2001-06-26
Chen, Sophia S. (Department: 2852)
Electrophotography
Internal machine environment
Forced air circulation
C355S030000, C399S045000, C399S094000
Reexamination Certificate
active
06253042
ABSTRACT:
CLAIM OF PRIORITY
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from my application
METHOD FOR CONTROLLING A FAN OF AN ELECTRONIC PHOTO DEVICE
filed with the Korean Industrial Property Office on Dec. 19, 1998 and there duly assigned Ser. No. 56407/1998.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for controlling a fan of an electronic photo device. More specifically, the present invention relates to a method for controlling the operation of the fan in the electronic photo device to keep the temperature in the device as a suitable level to the characteristics of print papers and thereby provide an enhanced print quality.
2. Description of the Related Art
Generally, an electronic photo device such as a copying machine and a printer includes a pickup roller, a charging roller, an organic photoconductive (OPC) drum, a transferring roller, a developing roller, a supplying roller, a fixing unit and an exposing device, a cleaning blade, a fan for keeping the temperature in the electronic photo device from increasing, an output sensor for sensing the output of a printed paper, and a printer controller for controlling the above-described components and performing data printing operation. By means of the components, the electronic photo device prints a predetermined image data on a print paper.
The charging roller, the developing roller, the transferring roller and the supplying roller are provided with a charging voltage of −1.4 kV, a developing voltage of −300 V, a transferring voltage of +2.0 kV, and a supplying voltage of −500 V, respectively.
Now, the printing process by the electronic photo device will be described hereinafter. First, the charging roller is charged by the charging voltage with a high pressure and rotated to evenly charge a photosensitive body formed on the outer periphery of the OPC drum. At this time, a light emitted from the exposing device forms an electrostatic latent image on the outer periphery of the charged OPC drum. Then, a potential difference occurs between the supplying roller supplied with a high pressure supplying voltage and the developing roller supplied with a lower voltage than the supplying roller.
Accordingly, negative charges move from the supplying roller to the developing roller. In this manner, toner is moved from the supplying roller to the developing roller. The toner is then coated on the electrostatic latent image formed on the outer periphery of the OPC drum so that the electrostatic latent image is changed into a visible image. The transferring roller with a high pressure transfers the visible image formed on the OPC drum with the toner to a transferred paper. The transferred visible image is fixed to the paper by heat and pressure of the fixing unit. In this manner, the printing process is completed.
On the other hand, the electronic photo device adopts at least a single fan to cool the heat used in fixing the toner to the print paper and keep the fixing temperature as a lower level than a predetermined temperature.
However, the electronic photo device including the fan suffers from several problems.
In the event that a great heat is initially supplied to the print paper with much toner coated thereon, there is a phenomenon that the paper is ironed by the heat and, resultantly, the paper may be wrinkled.
Moreover, in the case of an overhead projector (OHP) film, humidity and dyestuff of the overhead projector film is vaporized by the great heat. As a result, the fixed state of the toner is deteriorated and the printed image may be transformed.
Examples from the conventional art involving operation of electrophotographic devices are seen in the following U.S. Patents.
U.S. Pat. No. 5,379,999, to Barzideh et al, entitled Sheet Media Handling Apparatus, describes an electrophotographic device in which the sheet media is controlled by air from a fan.
U.S. Pat. No. 5,457,516, to Kim, entitled Energy Saving Image-Forming Apparatus And Control Method Therefor, describes a printer apparatus including a ventilation fan for cooling the internal portions of the printer. The method includes turning off the power to the fan when the apparatus fails to receive an input within a predetermined time period.
U.S. Pat. No. 5,666,187, to Kim, entitled Method And Apparatus For Controlling The Driving Of An Ozone Emission Fan In An Image Forming Apparatus, describes driving the ozone emission fan when an external printing command is received and stopping the ozone emission fan after the printing operation.
U.S. Pat. No. 5,956,554, to Yanashima et al, entitled Sheet Driving Prevention Device, describes a printer with fans in the vicinity of the fixing device to blow air onto a continuous form when printing is stopped, to prevent heating of the continuous form.
Based on my reading of the art, then, I have decided that what is needed is an improved method for operating an electrophotographic device which prevents damage to the image on an overhead projector film.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved method for operating an electrophotographic device.
It is a further object of the present invention to provide a method which prevents wrinkling of printing paper with a high level of toner.
Another object of the invention is to provide a method which prevents deterioration of the toner image on overhead projector film.
Yet another object of the present invention to reduce the noise of the cooling fan in the electrophotographic device.
To achieve the objects and other objects, the present invention provides a method for controlling the operation of the fan of the electronic photo device including a developing device, a fan for keeping the temperature in the electronic photo device uniformly, and an output sensor for sensing the output of a printed paper. According to the method, when a printable medium to be printed with print data is located between a transferring roller and an organic photoconductive drum of the developing device, it is determined what sort of printable medium the printable medium is. If it is determined that the printable medium is a first sort of printable medium, the fan is stopped and a fixing process is performed. Otherwise, if it is determined that the printable medium is a second sort of printable medium, the fixing step is performed under the condition that the fan is not stopped.
As an embodiment of the present invention, the first and the second sorts of printable mediums may be overhead projector film and general paper, respectively. Moreover, the sort ofthe printable medium may be determined by the resistance value of the printable medium.
Preferably, the method of the present invention further includes the steps of: determining whether the upper end, that is, the leading edge, of the fixed printable medium is passed by the output sensor or not; and if it is determined that the upper end of the fixed printable medium is passed by the output sensor, in the case that the fixed printable medium is the first sort of printable medium, stopping the fan and operating the fan again when the bottom end of the first sort of printable medium is passed by the output sensor, and, in the case that the fixed printable medium is the second sort of printable medium, operating the fan after the second sort of printable medium passes by a predetermined point, for example, 25 mm from the output sensor.
Preferably, the method of the present invention further includes the step of operating the fan by a predetermined rotating speed, for example, 60~70% of a normal rotating speed, for a predetermined time, for example, 30 seconds, after a printing process is completed.
REFERENCES:
patent: 5218411 (1993-06-01), Kosugiyama et al.
patent: 5379999 (1995-01-01), Barzideh et al.
patent: 5457516 (1995-10-01), Kim
patent: 5666187 (1997-09-01), Kim
patent: 5930572 (1999-07-01), Haneda et al.
patent: 5956554 (1999-09-01), Yanashima et al.
Bushnell , Esq. Robert E.
Chen Sophia S.
Samsung Electronics Co,. Ltd.
Tran Hoan
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