Canon Kabushiki Kaisha

Hiroshi Takami

Hiroaki Sakai

Tomohiro Nakamori

Masaru Shimura

Seiji Saito

Tomoyuki Makihira

Atsushi Iwasaki

Akira Kato

Junichi Kimizuka

Masafumi Maeda

Tatsuto Tachibana

Takeshi Kawamura

Masaru Tsukada

Yasunari Kobaru

Hiroshi Chihara

Soya Endo

Seietsu Miura

The image heating apparatus heats a toner image beard on a recording material while conveying the recording material at a nip portion, and includes: a heater; a fixing member; a pressure member; a first temperature detecting member; a second temperature detecting member configured to detect a temperature on non-sheet-passing area; a control device; and an air supplying member supplying an air to the non-sheet-passing area. The air supplying member is started to be drive when a temperature detected by the second temperature detecting member reaches a predetermined temperature which is higher than the target temperature. The control device controls the quantity of the air in response to information related to the power supplied to the heater when a temperature detected by the second temperature detecting member reaches the predetermined temperature.

Image heating apparatus having fixing member and supplying cooling air to a non-sheet-passing area for cooling the fixing member

An image forming apparatus includes a fixing unit, wherein the fixing unit includes a first temperature detection member detecting the temperature of a first non-passing area of the fixing unit; a second temperature detection member detecting the temperature of a second non-passing area; and a cooling unit supplying air so as to simultaneously cool the first non-passing area and the second non-passing area, wherein the image forming apparatus is configured, when the absolute value of the difference between the detection temperature of the temperature detection members becomes not less than a threshold value, while air is being supplied to the non-passing area and the second non-passing area, to stop the supplying of air by the cooling unit and continue recording material fixing processing.

Image forming apparatus

The power supply apparatus includes a plurality of voltage rising circuits each of which can be driven at a different duty ratio so as to convert and output a voltage output from a direct current power source according to a plurality of loads; and a control circuit which controls an input voltage from the direct current power source to each voltage rising circuit according to drive condition of the voltage rising circuit having the highest duty ratio of the plurality of voltage rising circuits. This configuration can provide a highly productive power supply apparatus capable of reducing a ripple voltage.

Power supply apparatus and image forming apparatus

A fixing apparatus that conveys a printing medium to a fixing nip portion formed by rotating members, and fixes an image onto the printing medium by heat from heating elements. The fixing apparatus also includes a safety element, a rotation detection circuit, and a limiting circuit. The safety element is in a power supply path to supply electrical power to the heating elements and to shut off the path in response with an abnormal temperature. The rotation detection circuit detects a rotation state of the rotating members. The limiting circuit limits a drive of a second driving circuit per a rotation detection circuit output. A first driving circuit detects that the circuit drives a first heating element per a control signal, regardless of the rotating members rotation state, and the second driving circuit drives a second heating element per a control signal and the output from the rotation detection circuit.

Fixing apparatus comprising circuit for suppressing heat generation according to rotation detection signal

A fixing apparatus including a rotation detection circuit which detects the rotation state of the rotating member or pressing member, and one to (N&#x2212;1) limiting circuits which limit driving of one to (N&#x2212;1) driving circuits in accordance with an output from the rotation detection circuit, wherein when the rotation detection circuit detects that the rotating member or pressing member is not rotating, the one to (N&#x2212;1) limiting circuits limit driving of the one to (N&#x2212;1) driving circuits in accordance with the output from the rotation detection circuit to suppress energization of the heating elements regardless of the driving signals from the control unit to the driving circuits.

An image fixing apparatus has an integration circuit which is provided in a signal path from a comparison circuit to a relay drive circuit and integrates a signal input to the integration circuit, wherein an integral value of the signal input to said integration circuit reaches a reference value; and a latch circuit having an input port connected to a signal path from said integration circuit to the relay drive circuit and an output port connected to a signal path from the comparison circuit to the integration circuit. The latch circuit continuously transmits a signal from said output port to the integration circuit, upon a change in a signal level of the input port so that the relay is switched to the open position, and latches the relay in the open position.

Image fixing apparatus with safety relay and control thereof

The n image heating apparatus for heating an image formed on a recording material, includes a heater including a substrate, and plural heat generating resistors formed on the substrate along a longitudinal direction thereof, and plural switching elements connected electrically between a power source and the plural heat generating resistors, wherein the plural heat generating resistors include at least two first heat generating resistors driven by a first switching element and at least a second heat generating resistor driven by a second switching element, and the second heat generating resistor is provided between the at least two first heat generating resistors in a direction of a shorter side of the substrate. In this manner there can be provided an image heating apparatus with a heater of an excellent durability, and a heater adapted for use in such apparatus.

Image heating apparatus and heater therefor

A jumper cable is provided in a connector connected to an output signal of a temperature detection device and a detection signal line of fixing device specification means, and electric power supply to the temperature detection device is connected though the jumper cable. Therefore, when an electric connector connecting a main body of an image forming apparatus and a fixing device is disconnected, the overheating of the fixing device is avoided.

Image forming apparatus and fixing device used therein

Disclosed is a heat fusing apparatus for thermally fusing toner that has been transferred to a printing medium from a toner image formed on an image bearing member using an electrophotographic process. Temperature is detected at the surface of a heating element or in the vicinity thereof. If control is performed so as to interrupt supply of power to the heating element based upon result of comparing the detected temperature and a reference value, the amount of current that flows into the heating element is detected and the reference value is changed over in accordance with the result of detection. Further, a pressure roller, which is a rotation member placed opposite the heating element, presses the printing medium against the heating element and transports the printing medium. The state of rotation of the roller is detected and the reference value is changed over in accordance with the result of detection. The apparatus prevents, without malfunction at the time of normal operation, the occurrence of a situation in which the entire fusing apparatus and peripheral devices must be repaired or replaced owing to overheating, and minimizes apparatus damage to thereby minimize the cost of replacement parts and service cost.

Heat fusing apparatus, method of controlling same and image forming apparatus

The image heating apparatus for heating an image formed on a recording material includes a heater having a substrate and first and second heat generating resistors, most of the region of said first heat generating resistor having smaller resistance value per unit length toward an end in the longitudinal direction of said substrate, and most of the region of said second heat generating resistor having larger resistance value per unit length toward the end part; wherein a safety element can control electrical power supply to said first heat generating resistor and electrical power supply to said second heat generating resistor individually, and operates in response to the heat of said heater to cut off electrical power supply to said first and second heat generating resistors; and wherein only said second heat generating resistor in said first and second heat generating resistors has a high resistance part high resistance part corresponding to said safety element in a part in the longitudinal direction thereof; and consequently, this can provide an image heating apparatus that can cut off electrical power supply quickly when a heater has run away and to provide a heater to be used in this apparatus.

Image heating apparatus and heater used therefor

An image forming apparatus includes a control voltage generation circuit which inputs a primary AC voltage to the primary side of a voltage transformer, generates a control voltage corresponding to a current generated on the secondary side of the voltage transformer in accordance with the primary AC voltage, and controls the primary AC voltage on the basis of the control voltage and a control signal, a current detection circuit which is connected, through a capacitor, to a path which supplies the current generated on the secondary side of the voltage transformer to a charge roller and detects a charge current to charge an image carrier, and a control circuit which determines the control signal on the basis of the relationship between a predetermined control signal (PRICNT) and a current value (Icap) detected by the current detection circuit in accordance with the predetermined control signal and controls the primary AC voltage to be generated by the voltage generation circuit.

Charge voltage control circuit and image forming apparatus which controls a charge voltage based on a discharge current

An AC voltage from a power generating circuit is applied to a charge roller. CPU controls the power generating circuit so as to flow a constant current according to a control value through a current path from the power generating circuit to the charge roller. CPU produces an information according to an peak value of the AC voltage applied to the charge roller. CPU produces an information according to the AC voltage applied to the charge roller when the AC voltage is in a predetermined phase.

An image forming system that can prevent the image carrier from wearing because of excessive discharge, even under property fluctuations in the charging unit and surrounding conditions, and can maintain stable, excellent image quality for a long time. The system lowers fluctuations in current detection by making the characteristic of the AC charge current detection circuit variable and switching the AC charge current detecting characteristics between the voltages lower than discharge threshold voltage and the voltages higher than that.

Image forming system and image forming method for deciding AC voltage to be applied to charger

An image forming apparatus is provided which is capable of reliably preventing a recording sheet wound around a roller member from being further wound around the roller member even when the power supply of the image forming apparatus is turned on/off while the recording sheet is wound around the roller member. A high voltage power supply section applies voltage to feeding brushes disposed in contact with the surface of a pressurizing roller having an electrically conductive surface. A winding sensor is disposed in contact with the surface of the pressurizing roller and is located in a sheet passing area of the pressurizing roller. A CPU provides control such that the pressurizing roller is inhibited from being driven when it determines that the recording sheet is caught between the pressurizing roller and the winding sensor according the result of comparison between the output voltage from the winding sensor and detected voltage of the feeding brushes.

Sheet winding detecting device and image forming apparatus

An image forming apparatus includes a process cartridge detachably mountable with respect to the main body of the apparatus. The process cartridge is provided with an image bearing member, a charger for charging the image bearing member, a power supply for applying an alternating current voltage to the charger, and a controller for variably controlling the alternating current supplied from the power supply to the charger in conformity with information about the use situation of the process cartridge. The process cartridge can also include an image bearing member, a charger for charging the image bearing member, the charger permitting an alternating current voltage to be applied thereto by a power supply, and a memory for storing therein information about the use situation of the process cartridge, and information of a plurality of preset control values for an alternating current supplied from the power supply to the charger to be variably controlled in conformity with the information.

Image forming apparatus and process cartridge for applying an alternating current to a charging member or charging means for charging an image bearing member

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Odawara, Japan

Hiroshi Takami