Electrophotography – Control of electrophotography process – Control of fixing
Reexamination Certificate
1999-12-28
2001-11-20
Grainger, Quana M. (Department: 2852)
Electrophotography
Control of electrophotography process
Control of fixing
C219S216000
Reexamination Certificate
active
06321046
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus and, more particularly, to an induction heating fixing device which uses an induction heating means as a heating source, and an image forming apparatus using the fixing device.
A fixing device which is related to the present invention uses a halogen lamp or the like as a heating source. The lamp is arranged inside a heat roller to heat it. A press roller is pressed against the heat roller and rotated so as to bring the print medium into press contact with the heat roller, and a paper sheet is passed between the two rollers.
FIG. 8
shows a schematic structure of the overall fixing device. A halogen lamp
102
is arranged inside a thin, metal heat roller
101
. An elastic member is formed on the surface of a press roller
103
to make the print medium in sufficient press contact with the heat roller
101
. The heat roller
101
and press roller
103
are supported while being applied with a predetermined pressure by a compression mechanism (not shown). Furthermore, the heat roller
101
and press roller
103
are rotated by a drive source (not shown) in the directions of arrows at the same speed as the convey speed of the print medium.
The fixing device using the halogen lamp
102
suffers poor thermal efficiency, and it is hard to reduce consumption power. Also, a long warm-up time is required from when the power supply is turned on until the heat roller
101
reaches the temperature required for fixing operation.
SUMMARY OF THE INVENTION
It is, therefore, an object of the present invention to provide a fixing device which can attain high thermal efficiency and power savings, and quickly becomes ready to start fixing operation after power ON, by a simple method.
According to the present invention, there is provided a fixing device used in an image forming apparatus, comprising a main body control circuit for controlling operation of the overall image forming apparatus, a member to be heated, an excitation coil which is arranged in the vicinity of the member to be heated and heats the member to be heated by induction upon receiving a current, and an induction heating control circuit for controlling current supply to the excitation coil, wherein the induction heating control circuit has a central processing unit independently of the main body control circuit so as to be able to control current supply to the excitation coil independently of control of the operation of the overall image forming apparatus by the main body control circuit.
The fixing device may further comprise an excitation circuit for supplying a high-frequency current to the excitation coil, and a control circuit for controlling operation of the excitation circuit, and the central processing unit of the induction heating control circuit may control supply of the high-frequency current to the excitation coil by controlling the operation of the control circuit on the basis of a heating ON/OFF signal supplied from the main body control circuit.
A fixing device according to the present invention is a fixing device used in an image forming apparatus, comprising a main body control circuit for controlling operation of the overall image forming apparatus, a member to be heated, an excitation coil which is arranged in the vicinity of the member to be heated and heats the member to be heated by induction upon receiving a current, an induction heating control circuit which has a central processing unit independent from the main body control circuit, and controls current supply to the excitation coil, and a sensor for detecting a temperature of the member to be heated, wherein the main body control circuit detects the temperature of the member to be heated using the sensor at the beginning of current supply to the member to be heated, and supplies a power control signal to the induction heating control circuit to obtain a power supply output on the basis of the detected temperature.
The main body control circuit preferably selects a lower power supply output as the temperature detected by the sensor becomes higher.
An image forming apparatus according to the present invention comprises a main body control circuit for controlling operation of the overall image forming apparatus, a member to be heated, an excitation coil which is arranged in the vicinity of the member to be heated and heats the member to be heated by induction upon receiving a current, an induction heating control circuit which has a central processing unit independent from the main body control circuit, and controls current supply to the excitation coil, and sleep mode setting means for, when the image forming apparatus remains non-operated for not less than a predetermined period of time, setting the image forming apparatus in a sleep mode having lower consumption power than a normal state, wherein when a request for operating the image forming apparatus is generated while the image forming apparatus is set in the sleep mode by the sleep mode setting means, the main body control circuit supplies a heating ON/OFF signal to the central processing unit of the induction heating control circuit in correspondence with a type of generated request, and initializes required mechanisms of the image forming apparatus in accordance with the type of generated request.
The image forming apparatus preferably further comprises a mechanism including a scanner and a document feeder required for FAX transmission, and when a FAX transmission request is generated while the image forming apparatus is set in the sleep mode, the main body control circuit initializes only the scanner and the document feeder.
The image forming apparatus further comprises a paper feed mechanism, process mechanism, scanner, and document feeder, and having an original copy function, FAX transmission/reception function, and image data print function, when the image forming apparatus is set in the sleep mode, the main body control circuit stops the paper feed mechanism, the process mechanism, the scanner, and the document feeder, and supplies an OFF signal to the induction heating control circuit, when a copy request is generated while the image forming apparatus is set in the sleep mode, the main body control circuit initializes the paper feed mechanism, the process mechanism, the scanner, and the document feeder, and supplies an ON signal to the induction heating control circuit, when a FAX transmission request is generated while the image forming apparatus is set in the sleep mode, the main body control circuit initializes the scanner and the document feeder, and when a FAX reception or image data print request is generated while the image forming apparatus is set in the sleep mode, the main body control circuit initializes the paper feed mechanism and the process mechanism, and supplies an ON signal to the induction heating control circuit.
REFERENCES:
patent: 5752150 (1998-05-01), Kato et al.
patent: 5794096 (1998-08-01), Okabayashi
patent: 5911094 (1999-06-01), Tsujimoto
Ebata Yasuhiro
Kikuchi Kazuhiko
Matsunai Tomohiro
Nakayama Hiroshi
Foley & Lardner
Grainger Quana M.
Toshiba Tec Kabushiki Kaisha
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