Photocopying – Contact printing – Light boxes
Patent
1992-06-10
1994-04-05
Grimley, A. T.
Photocopying
Contact printing
Light boxes
219216, G03G 1520
Patent
active
053010000
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
It is customary, in electrophotographic printers or copiers, to fix the recording medium, coated with toner, in a thermal fixing station. Thermal fixing stations of this type generally contain electrically heated fixing rollers having associated swing-to and swing-away pressure rollers. For the fixing, the recording medium is guided through between the fixing rollers and pressure rollers. The toner on the recording medium is fixed by the action of heat from the fixing roller. Since the toner has to be brought to melting temperature in the course of the short zone of contact of the recording medium with the fixing roller, a high heating capacity is necessary for the fixing roller. It is conventional, for this purpose, to install halogen radiators of high heating capacity in the hollow fixing roller.
But the disadvantage of halogen radiators is that their burning time is relatively short and that it is therefore necessary to exchange them quite frequently.
U.S. Pat. No. 4,493,982 makes known a device for extracting radiant heaters from the fixing station of a copier, which makes it possible to extract the radiant heater even in the hot state. The fixing roller remains in the housing of the machine.
European reference 0,184,202 (corresponding to U.S. Pat. No. 4,736,226) describes a fixing device having a fixing roller which is mounted on heating bars as bearing elements. To exchange the fixing roller, the heating bars are drawn out of the machine housing. An exchange of the fixing roller in the hot state is possible only with difficulty and only by a maintenance technician.
It has hitherto been customary, in the event of damage, for the exchange of the defective radiant heater and the defective fixing roller to be carried out by a trained maintenance technician, with the machine cold. This leads to a long machine shutdown and high expenditure for the repair of the machine. A particular disadvantage has been that, before the actual exchange, it has been necessary to wait until both the fixing roller and the halogen radiator to be exchanged have cooled. In view of the high thermal capacity of the fixing roller, this can take a relatively long time.
Moreover, to exchange the radiant heaters, it has been necessary to dismount the entire heating roller, thus additionally complicating the exchange.
Since the recording medium is moved between the fixing roller and pressure roller by means of friction, the pressure roller is subjected to relatively high wear. To exchange the pressure roller, it has hitherto been conventional to dismantle the entire fixing station. This involves a high outlay and leads to lengthy undesirable idle times of the printing apparatus.
SUMMARY OF THE INVENTION
The object of the invention is to design a fixing station of the type mentioned in the introduction, in such a way that it is of easy-to-maintain design, so that wearing parts can be exchanged without a special tool.
In a device of the type mentioned in the introduction, this object is achieved by a fixing station for an electrophotographic printing or copying apparatus, having an electrically heated fixing roller and a pressure roller swingable up to and away from the fixing roller via a fastening mechanism, wherein the fixing roller is designed as a hollow roller having heating elements arranged therein and is mounted in a stand of the fixing station via bearing flanges. A first bearing flange is fixed to the stand and a second bearing flange is releasably attached to the stand. Holding elements are designed in such a way that, for the extraction of the fixing roller from the fixing station, they connect the second bearing flange to the fixing roller and allow a separation of the second bearing flange from the extracted fixing roller.
Advantageous embodiments of the invention are as follows.
The second bearing flange has a handle element. The bearing flanges have centering elements which engage laterally into the fixing roller and on which the fixing roller rests and can slide. Spring elements are arra
REFERENCES:
patent: 4121089 (1978-10-01), Bishop
patent: 4493982 (1985-01-01), Romansky
patent: 4498757 (1985-02-01), Lance et al.
patent: 4736226 (1988-04-01), Mogi
patent: 4839694 (1989-06-01), Kawashima et al.
patent: 4899197 (1990-02-01), Davis et al.
IBM Technical Disclosure Bulletin, vol. 32 No. 1 Jun. 1989, "Customer Serviceable Hot Roll".
IBM Technical Disclosure Bulletin, vol. 32 No. 1 Jun. 1989, "Inside-out Fuser Roll Drive".
Beatty Robert
Grimley A. T.
Siemens Nixdorf Informationssysteme Aktiengesellschaft
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