Abstract: An image forming apparatus according to an embodiment includes a decolorable image forming unit that forms a decolorable image with a decolorable material. A mask control unit controls the decolorable image forming unit to form, with the decolorable material on a sheet, a mask that hides at least one portion of an image formed on the sheet with non-decolorable material.

Abstract: An image forming apparatus according to an embodiment includes a decolorable image forming unit that forms a decolorable image with a decolorable material. A mask control unit controls the decolorable image forming unit to form, with the decolorable material on a sheet, a mask that hides at least one portion of an image formed on the sheet with non-decolorable material.

Abstract: According to one embodiment, an image forming apparatus includes a lubricant having a bar shape along the axial direction of a transfer roller, a brush roller which applies a component of the lubricant to the surface of the transfer roller, and a plurality of bases which are made of metal and are disposed at intervals along the axial direction of the transfer roller. The bases hold the lubricant in a state where the lubricant comes in contact with the brush roller.

Abstract: A developing roller according to the invention includes a columnar magnet roller, and a cylindrical sleeve that houses the magnet roller. A plurality of fragmented micro recesses is formed on the surface of the sleeve. The micro recesses are arranged dispersively both in an axial direction and in a circumferential direction of the sleeve.

Abstract: A developing roller according to the invention includes a columnar magnet roller, and a cylindrical sleeve that houses the magnet roller. A plurality of fragmented micro recesses is formed on the surface of the sleeve. The micro recesses are arranged dispersively both in an axial direction and in a circumferential direction of the sleeve.

Abstract: An image-forming apparatus includes a rotary developing device including a casing having absolute value of the surface potential of not larger than 300 V.

Abstract: An image-forming apparatus includes a rotary developing device including a casing having absolute value of the surface potential of not larger than 300 V.

Abstract: An image-forming apparatus includes a rotary developing device including a casing having absolute value of the surface potential of not larger than 300 V.

Abstract: Disclosed is an image-forming apparatus comprising a rotary developing device including a casing having absolute value of the surface potential of not larger than 300 V.

Abstract: In an image forming apparatus according to the invention, the potential of an optical semiconductor is increased in a predetermined time period, in which a recording medium does not exist in a transfer region between the optical semiconductor and a transfer unit, so as to set a difference between a developing bias voltage and the potential of the optical semiconductor larger than a difference therebetween assumed when toner is being transferred onto the recording medium.

Abstract: An image forming device is provided including a plurality of developing devices changeable between at least a developing position and a standby position. The image forming device estimates a toner coverage rate for a first developing device at the developing position. If the estimated toner coverage rate is higher than a predetermined value, the first developing device is replenished with toner when a first print is printed before being changed to the standby position. If the estimated toner coverage rate is equal to or less than the predetermined value, the first developing device is replenished with toner before being changed to the developing position for a second print from the standby position.

Abstract: Toner replenishing device and method in an image forming apparatus are provide, which solve the disadvantages inherent in detecting the density of toner on the development sleeve at the standby position of the revolver and make possible stabilized toner density controlling irrespective of whether the coverage rate of the original rate is low or high.

Abstract: In an image forming apparatus according to the invention, the potential of an optical semiconductor is increased in a predetermined time period, in which a recording medium does not exist in a transfer region between the optical semiconductor and a transfer unit, so as to set a difference between a developing bias voltage and the potential of the optical semiconductor larger than a difference therebetween assumed when toner is being transferred onto the recording medium.

Abstract: A fixing device in an image forming apparatus can set its fixing temperature to 200.degree. C. in the copy mode, and 180.degree. C. to 160.degree. C. in the printer mode. When print data is externally input, a print mode is set, and the copy mode can be set on the image forming apparatus side. Since a fixing temperature is selected in accordance with the mode, a deterioration in image quality due to a fixing operation can be prevented, and both a high fixing ratio and high image quality can be realized.

Abstract: An oil cooler system for a motor vehicle with a turbo charger has an oil circuit which is constituted by a first oil circuit connecting an oil pan, an oil pump, an oil filter, an oil cooler, a turbo charger and the oil pan in that order. A second oil circuit connects the oil pan, the oil pump, the oil filter, a cylinder block of an engine and the oil pan in that order, providing an oil cooler of the partial-flow type (in which, after passage through the oil cooler, the oil is returned to the oil pan through the turbo charger alone). Since the oil which has been cooled through the oil cooler is sent directly to the turbo charger, the oil temperature at the inlet of the turbo charger is effectively lowered.