Abstract: A motor driving apparatus for constant-current control of a current of a coil of a motor includes a detector detecting the current, and a controller for controlling every first cycle to feed the coil until the current reaches a target value, and to decay the current after the current reaches the target value. The controller selects, every second cycle shorter than the first cycle, between decaying the current in a first mode and decaying the current in a second mode, in which a decay rate is lower than the first mode. In addition, the controller decays the current in the first mode when the current is equal to or higher than a predetermined threshold, and decays the current in the second mode when the current is lower than the predetermined threshold.

Abstract: A heating device and an image forming apparatus which make it possible to improve the degree of freedom in design to enhance the accuracy of detecting the state of a to-be-heated member, and easily reduce cost. An induction heating coil generates magnetic flux by flow of electric current therethrough. Ferrite cores formed of a magnetic material form magnetic paths. The fixing belt generates heat by the action of the magnetic flux generated by the induction heating coil 101. An antenna is disposed in an area at a location opposite to the fixing belt 120 with the ferrite cores therebetween, for detecting magnetic flux passing through the area. A control circuit determines whether or not the state of the fixing belt has changed, based on a result of detection by the antenna.

Abstract: The invention reduces loss produced when a power supply device supplies power to a fixing unit of a copier, thereby contributing to a reduction in size, a saving in terms of energy and lower cost. To achieve this, it is arranged so that it is possible to vary the capacitance of a resonant capacitor C200 that constructs a resonant circuit together with a coil 71 through which a high-frequency current flows in order to produce an induced electromotive force in an electrically conductive heating element. In an interval in which a tail current flows after closure of an IGBT 401 that switches the coil current, the capacitance of the resonant capacitor C200 of a switching element SW402 is increased, thereby suppressing a rise in voltage Vce of the IGBT 40 over a fixed interval of time. As a result, loss ascribable to the tail current is reduced.

Abstract: An image forming apparatus configured to apply a necessary amount of a lubricant to an image bearing member while preventing the lubricant from being excessively consumed. An intermediate transfer belt drive motor controlled by a PID controller drives an intermediate transfer belt. A brush rotation controller for controlling an application brush drive motor detects fluctuation in a frictional force between a cleaning blade and the intermediate transfer belt, and controls the application brush drive motor such that an amount of lubricant to be applied is an amount corresponding to the detected fluctuation in the frictional force.

Abstract: A heating device and an image forming apparatus which make it possible to improve the degree of freedom in design to enhance the accuracy of detecting the state of a to-be-heated member, and easily reduce cost. An induction heating coil generates magnetic flux by flow of electric current therethrough. Ferrite cores formed of a magnetic material form magnetic paths. The fixing belt generates heat by the action of the magnetic flux generated by the induction heating coil 101. An antenna is disposed in an area at a location opposite to the fixing belt 120 with the ferrite cores therebetween, for detecting magnetic flux passing through the area. A control circuit determines whether or not the state of the fixing belt has changed, based on a result of detection by the antenna.

Abstract: A heating device capable of accurately determining a change in the state of a to-be-heated member, caused in a narrow area. An induction heating coil generates magnetic flux by flow of electric current therethrough. The fixing belt generates heat by the action of the magnetic flux generated by the induction heating coil. A first antenna is disposed at a location where the magnetic flux generated by the induction heating coil can be detected assuming that there is no fixing belt. A second antenna is disposed such that at least some area of the second antenna overlaps the first antenna. A control circuit determines whether or not a state of the fixing belt has changed, based on a result of detection by the first antenna and a result of detection by the second antenna.

Abstract: The invention reduces loss produced when a power supply device supplies power to a fixing unit of a copier, thereby contributing to a reduction in size, a saving in terms of energy and lower cost. To achieve this, it is arranged so that it is possible to vary the capacitance of a resonant capacitor C200 that constructs a resonant circuit together with a coil 71 through which a high-frequency current flows in order to produce an induced electromotive force in an electrically conductive heating element. In an interval in which a tail current flows after closure of an IGBT 401 that switches the coil current, the capacitance of the resonant capacitor C200 of a switching element SW402 is increased, thereby suppressing a rise in voltage Vce of the IGBT 40 over a fixed interval of time. As a result, loss ascribable to the tail current is reduced.

Abstract: A motor driving apparatus for constant-current control of a current of a coil of a motor, including: a detector detecting the current; and a controller for controlling every first cycle to feed the coil until the current reaches a target value, and to decay the current after the current reaches the target value, wherein the controller selects, every second cycle shorter than the first cycle, between decaying the current in a first mode, and decaying the current in a second mode of which a decay rate is lower than the first mode, and wherein the controller decays the current in the first mode when the current is equal to or higher than a predetermined threshold, and decays the current in the second mode when the current is lower than the predetermined threshold.