Abstract: A heating element includes an excitation coil disposed adjacent the heating element; a voltage source for applying to the excitation coil a high frequency electric power provided by modulating an input AC electric power with a high frequency, wherein the heating element is heated by induction by the excitation coil supplied with the high frequency electric power, wherein the heating element has a characteristic frequency which is unequal to integer multiple s of a frequency of the the AC electric power.

Abstract: A heating element includes an excitation coil disposed adjacent the heating element; a voltage source for applying to the excitation coil a high frequency electric power provided by modulating an input AC electric power with a high frequency, wherein the heating element is heated by induction by the excitation coil supplied with the high frequency electric power, wherein the heating element has a characteristic frequency which is unequal to integer multiple s of a frequency of the AC electric power.

Abstract: There is provided an image forming system that is capable of making uniform in size printed images, which should originally be the same in size, between transfer sheets on which the images have been printed by a plurality of printers having different functions and capabilities when enough time has elapsed after fixing. In each of the printers, an image controller or the like forms predetermined marks on a transfer material, and a fixing device thermally fixes of the predetermined marks formed on the transfer material, and a mark detecting device or the like detects the predetermined marks. A host server connected to the printers via a network adjusts the sizes of images to be formed by the respective printers according to the predetermined marks detected by the respective printers, and then transfers the image data to the printers. Each of the printers performs image formation based on the transferred image data.

Abstract: A heating element includes an excitation coil disposed adjacent the heating element; a voltage source for applying to the excitation coil a high frequency electric power provided by modulating an input AC electric power with a high frequency, wherein the heating element is heated by induction by the excitation coil supplied with the high frequency electric power, wherein the heating element has a characteristic frequency which is unequal to integer multiple s of a frequency of the AC electric power.

Abstract: There is provided a sheet detecting apparatus which detects the position of a sheet as it is conveyed through a conveying path and has reached a predetermined position. The surface condition and thickness of the sheet are also detected and a correction system is provided for correcting the position detecting result in accordance with the detected thickness and surface condition. Also provided is a conveying apparatus in which the conveyance of the sheet is controlled on the basis of the corrected sheet position detection.