Electrophotography – Image formation – Fixing
Reexamination Certificate
2000-05-09
2001-07-17
Grimley, Arthur T. (Department: 2852)
Electrophotography
Image formation
Fixing
Reexamination Certificate
active
06263182
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to an electronically controlled oil dispenser for an image forming apparatus and, more particularly, to an oil dispenser having a piezo element for distributing oil to a roller within the image forming apparatus.
BACKGROUND OF THE INVENTION
The printing process of an image forming device, such as a laser printer, includes distributing toner to a recording sheet. The toner is usually a fine powder made of plastic granules that is transferred from a photoconductive drum, or intermediate transfer device, to the recording sheet. The toner is then fixed to the recording sheet by applying heat and/or pressure. In one popular embodiment, the heat and/or pressure is applied through a pair of fuser rollers that are spaced a distance apart between which the recording sheet and toner pass.
Problems may occur when the recording sheet with toner passes through the fuser rollers. One problem occurs when the toner on the recording sheet adheres to one of the fuser rollers resulting in image contamination as the toner does not adhere to the correct location on the recording sheet, or remains on the roller and is not transferred to the recording sheet. Another problem occurs when the recording sheet is inadvertently wound around one of the fuser rollers causing a jam.
To overcome these problems, oil is applied to one or both of the fuser rollers. The oil reduces the amount of toner that adheres to the rollers, and also lessens the likelihood of the recording sheet becoming entangled. An oil applicator is positioned adjacent to the rollers for distributing the oil. However, the application of oil to the fuser rollers may result in additional problems.
One problem is inconsistent oil transfer to the rollers during the life of the oil applicator. Many designs result in an over-abundance of oil being transferred to the fuser roller early in the life of the applicator. Too much oil distributed onto the rollers may be transferred to the recording sheet resulting in oil spots that are visible to the user thereby ruining the sheet. Conversely, the same applicators often do not apply an adequate amount of oil during the end of their life. Inadequate oil results in toner adhering to the fuser rollers and/or the recording sheet sticking to the fuser rollers, both of which are unacceptable results. Inconsistent oil application also makes it difficult to predict the expected life of the oil applicator.
Many currently existing oil applicators are messy to install and remove from the image forming device. One common design features a pad through which oil is applied and then wicked to the fuser rollers. Installation of this type of applicator may require that the pad be doused with oil during the installation which may result in oil contacting the user and also portions of the image forming device which may then be transferred to the recording sheet. Removal of a used oil applicator may again be messy as the oil applicator may be coated with oil that was dispelled during use. The oily applicator may inadvertently contact other parts of the image forming device or get on the user's hands or clothes.
Therefore, there is a need for an oil applicator that coats the fuser roller with a consistent amount of oil during its life, and is not messy to install and remove from the image forming apparatus.
SUMMARY OF THE INVENTION
The oil applicator of the present invention distributes oil to one of the fuser rollers to reduce and eliminate toner adherence and sheet jams within the rollers. The device includes an oil reservoir for housing the oil with at least one ejection port positioned within the reservoir. A seal is disposed adjacent to the ejection port and is movable between a closed position where the seal effectively closes the ejection port and an open position where the seal is spaced from the outlet such that oil may flow through the ejection port. At least one piezo element is positioned for moving the seal between the open and closed positions in response to the piezo element being switched between energized and non-energized states.
The applicator may also include a diaphragm that extends over at least a portion of the oil reservoir. In this embodiment, both the seal and piezo element are secured to the diaphragm. A pad may be disposed adjacent to the ejection port of the oil reservoir to receive oil and transfer it to the roller.
A processor may control the activation of the piezo element such that a substantially equal volume of oil is dispensed through the ejection port for each cycle between the energized and non-energized states. The processor may be connected to a voltage source for supplying voltage to and activating the piezo element. The processor may also monitor the number of recording sheets passing through the fuser rollers and cycle the piezo elements based on the number. For example, the processor may cycle the piezo element to distribute oil after every five recording sheets have passed through the rollers. Likewise, a sensor may be positioned within the image forming apparatus for sensing the installation of a new oil applicator. The sensor signals the processor of the new applicator, resulting in the processor cycling the piezo elements a predetermined number of times to ensure an adequate oil supply is distributed to the rollers.
The applicator may also include a supply tank for holding an additional amount of oil. The supply tank is connected to the oil reservoir and supplies the oil, preferably via gravity.
The oil reservoir may further include a number of individual cells each having at least one ejection port. A separate piezo element may be positioned over each of the cells for controlling the distribution of oil. Each piezo element may be individually energized to control the location of where the oil is distributed to the roller.
The invention also includes a method of dispensing oil from the oil reservoir by energizing a piezo element thereby opening an ejection port within the oil reservoir. The oil flow is stopped by de-energizing the piezo element thereby closing the ejection port within the oil reservoir. Within the method, energizing the piezo element moves a seal from a closed position over the ejection port, and de-energizing the piezo element returns the seal to the closed position.
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Baker Raymond Milton
Bussiere Ronald Paul
Hutchinson John William
Shadwick David Thomas
Coats & Bennett PLLC
Grimley Arthur T.
Lexmark International Inc.
Ngo Hoang
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