Abstract: A heating apparatus which can increase the temperature of a heating element to a target temperature in a short time and ensures temperature uniformity of the heating element. In the heating apparatus, when the specific resistance of a material of a heat generating layer (212) of a heating roller (210) is ? (??cm), the average thickness of the heat generating layer (212) is 5? (?m) or more but not more than 15? (?m) and the thickness error is 1.2? (?m) or less. For instance, in the case of forming the heat generating layer (212) by using cupper having a specific resistance of 1.7 (??cm), the average thickness of the heat generating layer (212) is 8-25 (?m) and the thickness error is 2 (?m) or less. Thus, the heating roller (210) having a short heat increasing time and excellent temperature uniformity is provided.

Abstract: A fixing apparatus that enables the calorific value of a heat-producing rotating element to be stabilized and the heat production efficiency of that heat-producing rotating element to be improved. A fixing apparatus (200) is equipped with a heat-producing sleeve (210), an induction heating apparatus (230), a magnetic field absorption member (233) that absorbs a magnetic field generated by the induction heating apparatus (230), and a fixing roller (240) and pressure roller (250) that grip and rotate the heat-producing sleeve (210). The magnetic field absorption member (233) is located in an area opposite an exciting coil (231) with the heat-producing sleeve (210) between, and absorbs a magnetic field generated by the induction heating apparatus (230). The heat-producing sleeve (210) is composed of a nonmagnetic metallic material of thickness in the range from 10 ?m to 500 ?m and specific resistance of 80×10?6 ?cm or less.

Abstract: The present invention relates to an image forming apparatus that enables the occurrence of print defects due to a first print start time delay to be eliminated without using a temperature sensor that has a small thermal time constant. When the temperature of a fixing belt serving as an image heating body is greater than or equal to a predetermined temperature following the elapse of a fixed time after an image forming operation is started, recording paper is transported to a nip area (fixing area) of a fixing apparatus before the temperature detected by a temperature sensor reaches a predetermined image fixing temperature, and an image forming operation is started immediately.

Abstract: An image heating apparatus that enables a temperature of an image heating element to be stably maintained at a target temperature as a fixing speed varies. A Proportional-Integral-Derivative (PID) controller determines whether a temperature control computation results in a range that allows temperature control with one IGBT, and a linear control is performed if the result is at least equal to a minimum power obtained as IH output. PWM control is performed at minimum power if the power is less than a required minimum power. Thus, a computation method of a supply power computator need not be switched according to the fixing speed, and a calorific value of a fixing belt can be controlled using one computation method.

Abstract: PID control performs integral control using an integral value of a deviation between a set temperature and current temperature. In particular, when a proportionality factor Kp is large, a fixing belt reaches a target temperature quickly but overshoot increases. On the other hand, when the proportionality factor Kp is small, the output is reduced gradually, and therefore the fixing belt reaches a target temperature slowly but the overshoot is small. Thus, a heat value control section changes the control value of the PID control according to the temperature (belt temperature) of a fixing belt at the start of heating as detected by a temperature detector. More specifically, a proportionality factor Kp of a calculation expression of the PID calculation is changed according to the belt temperature of the fixing belt. This makes it possible to reduce an overshoot when the temperature of the fixing belt increases.

Abstract: A fixing apparatus is provided that enables a recording medium that has undergone heat-fixing to be separated smoothly from a heating medium without causing a sheet jam or image disturbance. In this apparatus, there are provided on the guide surface of a separator two step parts raised along the guide surface guide width direction. Recording paper is transported gripped by a fixing nip, is guided so as to come into contact with only the apex parts of step parts, and is separated from the surface of a fixing belt. Thus, a gap is formed between the guide surface and the heat-fixing surface of recording paper guided along the guide surface, the contact area between the heat-fixing surface of recording paper and the guide surface decreases, the heat-fixing surface of recording paper becomes less prone to adhere to the guide surface of the separator, and recording paper is smoothly separated from the fixing belt without causing a sheet jam or image disturbance.

Abstract: An image fixing device that is controllable with a high degree of reliability. The image fixing device is configured with a heat generator for fixing a toner image onto a recording medium that is opposed to an induction heater. Heat is generated in the heat generator through electromagnetic induction. An inverter circuit drives the induction heater. A power controller controls a power value that is output from the inverter circuit, whose power value is calculated by a power-value calculator. A power-value sensor acquires the power value output from the power controller, and a temperature sensor senses a temperature at least at one point of the heat generator. Thus, either the power value sensed by the power-value sensor or a temperature value sensed by the temperature sensor may be used as a reference value to calculate the power value in the power-value calculator.

Abstract: A fixing apparatus that enables the calorific value of a heat-producing rotating element to be stabilized and the heat production efficiency of that heat-producing rotating element to be improved. A fixing apparatus (200) is equipped with a heat-producing sleeve (210), an induction heating apparatus (230), a magnetic field absorption member (233) that absorbs a magnetic field generated by the induction heating apparatus (230), and a fixing roller (240) and pressure roller (250) that grip and rotate the heat-producing sleeve (210). The magnetic field absorption member (233) is located in an area opposite an exciting coil (231) with the heat-producing sleeve (210) between, and absorbs a magnetic field generated by the induction heating apparatus (230). The heat-producing sleeve (210) is composed of a nonmagnetic metallic material of thickness in the range from 10 ?m to 500 ?m and specific resistance of 80×10?6 ?cm or less.

Abstract: An image heating apparatus is provided that enables the temperature of an image heating element to be maintained stably at a target temperature even when the fixing speed varies, and that enables lower cost and higher efficiency to be achieved. In this apparatus, with a calorific value control section 300 of a fixing apparatus 200, temperature control computation is not varied according to the rotational speed of a fixing belt 230, but it is determined whether a PID control computation result is in a range that allows temperature control with one IGBT, linear control is performed if the result is greater than or equal to the minimum power obtained as IH output, and PWM control is performed at minimum power if power less than or equal to the minimum power is required. It is thus not necessary for the computation method of a supply power computation section 301 to be switched according to the fixing speed, and the calorific value of fixing belt 230 can be controlled with one computation method.

Abstract: The present invention provides an induction heating apparatus including a fixing belt that heats an unfixed image on recording paper, an excitation coil that induction-heats the fixing belt, an inverter circuit that supplies power to the excitation coil, a harness that electrically connects the excitation coil and the inverter circuit. The harness is constructed of a litz wire having a resistance of the harness section of 0.016 ? or below formed by stranding several tens of wires which are conductive wires coated with an insulator into a predetermined thickness.

Abstract: The present invention relates to an image forming apparatus that enables the occurrence of print defects due to a first print start time delay to be eliminated without using a temperature sensor that has a small thermal time constant. When the temperature of a fixing belt serving as an image heating body is greater than or equal to a predetermined temperature following the elapse of a fixed time after an image forming operation is started, recording paper is transported to a nip area (fixing area) of a fixing apparatus before the temperature detected by a temperature sensor reaches a predetermined image fixing temperature, and an image forming operation is started immediately.

Abstract: A fixing apparatus is provided that enables a recording medium that has undergone heat-fixing to be separated smoothly from a heating medium without causing a sheet jam or image disturbance. In this apparatus, there are provided on the guide surface of a separator two step parts raised along the guide surface guide width direction. Recording paper is transported gripped by a fixing nip, is guided so as to come into contact with only the apex parts of step parts, and is separated from the surface of a fixing belt. Thus, a gap is formed between the guide surface and the heat-fixing surface of recording paper guided along the guide surface, the contact area between the heat-fixing surface of recording paper and the guide surface decreases, the heat-fixing surface of recording paper becomes less prone to adhere to the guide surface of the separator, and recording paper is smoothly separated from the fixing belt without causing a sheet jam or image disturbance.

Abstract: An image heating device is operational to estimate a temperature of a pressure roller so as to determine a set temperature for a roller belt in a subsequent image heating period.

Abstract: An image heating device is provided with reduced cost, by which a difference in glossiness among printed images on recording media is eliminated, and the wrapping of a belt and the like at a high temperature is prevented. In the image heating device, controlling means estimates a temperature of a pressure roller according to at least one of a temperature of a belt detected by a temperature sensor and a variation with time in the detected temperature from completion of the heating after application of an electric power to the magnetization coil by an exciting circuit is stopped and the heating of the belt by the heating roller is stopped, so as to determine a set temperature for the belt in a subsequent image heating period.

Abstract: An image heating device is provided with reduced cost, by which a difference in glossiness among printed images on recording media is eliminated, and the wrapping of a belt and the like at a high temperature is prevented. In the image heating device, a controller estimates a temperature of a pressure roller according to at least one of a temperature of a belt detected by a temperature sensor and a variation with time in the detected temperature from completion of the heating after application of an electric power to the magnetization coil by an exciting circuit is stopped and the heating of the belt by the heating roller is stopped, so as to determine a set temperature for the belt in a subsequent image heating period.

Abstract: In a fixing unit 230, a medium introducing port 250 is provided near a gripping part 230a of a housing 230, and a sheet material 90 to be subjected to a fixing process is guided to the medium introducing port. A shutter 260 is provided slanted at a given angle with respect to a gripping surface 240 of the gripping part 230a of the fixing unit 230 such that the shutter has a fulcrum at a part thereof, which is closer to the gripping part 230a of the fixing unit 230, at the medium introducing port 250, and the shutter 260 is turnable to a position to close the medium introducing port 250 while resisting the urging forces of the twisted springs 270.

Abstract: PID control performs integral control using an integral value of a deviation between a set temperature and current temperature, and therefore when a proportionality factor Kp is large, a fixing belt 230 reaches a target temperature quickly but a subsequent overshoot increases. On the other hand, when the proportionality factor Kp is small, the output is reduced gradually, and therefore the fixing belt 230 reaches a target temperature slowly but the overshoot is small. Thus, a heat value control section 300 changes the control value of the PID control according to the temperature (belt temperature) a fixing belt 230 at the start of heating of detected by a temperature detector 270. More specifically, a proportionality factor Kp of a calculation expression of the PID calculation is changed according to the belt temperature of the fixing belt 230. This makes it possible to reduce an overshoot when the temperature of the fixing belt 230 increases.

Abstract: The present invention provides an induction heating apparatus including a fixing belt that heats an unfixed image on recording paper, an excitation coil that induction-heats the fixing belt, an inverter circuit that supplies power to the excitation coil, a harness that electrically connects the excitation coil and the inverter circuit. The harness is constructed of a litz wire having a resistance of the harness section of 0.016 ? or below formed by stranding several tens of wires which are conductive wires coated with an insulator into a predetermined thickness.

Abstract: A fixing device as an image heating device is provided, by which a difference in glossiness is not caused in a recording medium in the axial direction of a pressure roller. When a print request is issued during the end-processing sequence, an electric power applied to a magnetization coil via an exciting circuit is dropped to 0 by controlling means during the start-processing sequence, and after an appropriate interval, the heating with full power is restarted by the controlling means. By so doing, the decrease in temperature at both ends of a fixing belt and a heat-generating roller in the axial direction can be compensated.

Abstract: Disclosed is a printer apparatus that ensures temperature control of a heat-up roller in a fixing unit thereof. An image-forming unit forms an image to be transferred onto a recording material. The fixing unit fixes the image onto the recording material. The fixing unit includes a heat-up roller, a heating section for heating the heat-up roller, a power supply section for supplying power to the heating section, and a heat controller for controlling the power supply section. The heat controller is disposed in contact with the inner circumferential surface of the heat-up roller. When heated to temperatures above a predetermined value, the heat controller is thermally deformed and leaves the inner circumferential surface of said heat-up roller to interrupt the power supply of the power supply section to the heating section.