Electrophotography – Control of electrophotography process – Control of fixing
Reexamination Certificate
1999-06-09
2001-10-30
Grimley, Arthur T. (Department: 2852)
Electrophotography
Control of electrophotography process
Control of fixing
C219S216000, C399S067000
Reexamination Certificate
active
06311028
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a fixing apparatus by which a toner image formed by an electrophotographic method is fixed on the recording sheet, and particularly to a roller fixing apparatus and a belt fixing apparatus, by which the toner image is heated and fixed.
In a heat roller fixing apparatus, it is widely conducted that temperature of the fixing apparatus is controlled to a predetermined value by using a fixing temperature sensor such as a thermistor, or the like. In this case, it is normally conducted that a variation of the fixing temperature is reduced by using a plurality of heaters and by respectively on/off controlling them, and thereby fine fixing effects and stable fixing performance are secured.
In the on/off control of such the conventional fixing apparatus, there are following problems.
An image forming apparatus such as a copier, facsimile apparatus, into which the fixing apparatus according to the present invention is incorporated, is widely used in offices or shops, and is one of apparatus which are operated by the largest current. Almost all of the current supplied into the image forming apparatus is consumed in heaters of the fixing apparatus. Accordingly, power supply voltage is fluctuated when large current of heaters of the fixing apparatus is turned on/off, and the voltage supply onto the other apparatus in the room in which the image forming apparatus is installed, is affected. That is, such phenomena occur that illumination lamps in the room such as fluorescent lamps and incandescence lamps, flicker, thereby, environmental conditions of the room are badly affected.
In the present situation in which many OA apparatus are fully installed in the room and thereby, the environmental condition of the room is going to be worse, such the flicker of the room lamps is a problem to be solved. In the world, there is the trend to regulate such the flicker of the room lamps by regulations.
In the conventional technology in which the plurality of heaters are individually on/off controlled based on the fixing temperature sensors, there is a problem that the number of times of on/off operations is large, and thereby the number of occurrence of flickers is high.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to solve such the problem in the conventional technology, and to provide a fixing apparatus by which the flicker of the illumination lamp in the room, in which an image forming apparatus is installed, is reduced.
The object of the present invention is attained by any of the following structures (1)-(7).
Structure (1): An fixing apparatus in which a plurality of heaters are provided; image formation is carried out by turning on a part of the plurality of heaters; and heaters are controlled such that when fixing temperature is lowered, all heaters are turned on, thereby the lowered temperature is recovered, wherein, when it is measured by a timer that continuous on-time of a part of heaters exceeds the predetermined time, such control is carried out that the remaining heaters in addition to the part of heaters are turned on, thereby, the lowered temperature is recovered.
Structure (2): The fixing apparatus according to Structure (1), wherein the fixing apparatus has a fixing temperature sensor to detect the fixing temperature, and when it is detected by the fixing temperature sensor that the fixing temperature exceeds a first predetermined value, such control is carried out that all of the plurality of heaters are turned off.
Structure (3): The fixing apparatus according to Structure (1), wherein the fixing apparatus has a fixing temperature sensor to detect the fixing temperature, and when it is detected that the fixing temperature exceeds a second predetermined value by turning on the other heaters, the timer is reset.
Structure (4): The fixing apparatus according to Structure (1), wherein the fixing apparatus has a fixing temperature sensor to detect the fixing temperature, and when it is detected that the fixing temperature exceeds a second predetermined value by turning on the other heaters, the other heaters are turned off.
Structure (5): The fixing apparatus according to Structure (4), wherein, when the fixing temperature is not higher than the first predetermined value by turning off the other heaters, the timer is started.
Structure (6): The fixing apparatus according to Structure (5), wherein the fixing apparatus has a fixing temperature sensor to detect the fixing temperature, and when it is detected that the fixing temperature is not higher than the first predetermined value, the timer is started.
Structure (7): The fixing apparatus according to any of Structures (1) to (6), wherein the part of heaters has a calorific value necessary for keeping the fixing temperature in the vicinity of the temperature required for fixing the toner image during image formation.
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Bierman Jordan B.
Bierman, Muserlian and Lucas
Grimley Arthur T.
Konica Corporation
Ngo Hoang
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