Abstract: An image forming apparatus which allows an independent and easy replacement of replaceable image forming devices including an image forming unit detachably provided in the image forming apparatus. The image forming unit includes a housing, a plurality of replaceable devices, and a nonvolatile memory. The plurality of replaceable devices are replaceably mounted inside the housing. The nonvolatile memory is mounted on the housing and stores lifetime information of the image forming unit and each one of the plurality of replaceable devices.

Abstract: A belt rotates and carries a plurality of images. A scale is provided along at least one side of entire of the belt. A sensor reads the scale on the belt to obtain scale information. An actual speed calculating unit calculates a speed of the belt from the scale information. A control unit provides a control to correct speed of the belt according to the speed calculated. The control unit includes a frequency-correcting unit that performs correction of only a frequency component that is fluctuating of low frequency that is smaller than a predetermined frequency that is developed due to a change in a speed of the belt, from among speed fluctuations of the belt to adjust the speed of the belt to a predetermined target speed.

Abstract: An image forming apparatus which allows an independent and easy replacement of replaceable image forming devices includes an image forming unit detachably provided in the image forming apparatus. The image forming unit include a housing, a plurality of replaceable devices, and a nonvolatile memory. The plurality of replaceable devices are replaceably mounted inside the housing. The nonvolatile memory is mounted on the housing and stores lifetime information of the image forming unit and each one of the plurality of replaceable devices.

Abstract: A belt rotates and carries a plurality of images. A scale is provided along at least one side of entire of the belt. A sensor reads the scale on the belt to obtain scale information. An actual speed calculating unit calculates a speed of the belt from the scale information. A control unit provides a control to correct speed of the belt according to the speed calculated. The control unit includes a frequency-correcting unit that performs correction of only a frequency component that is fluctuating of low frequency that is smaller than a predetermined frequency that is developed due to a change in a speed of the belt, from among speed fluctuations of the belt to adjust the speed of the belt to a predetermined target speed.

Abstract: An image forming apparatus includes an apparatus body and a rotary developing unit or revolver. The apparatus body includes a connection unit having a single optical transmission/receipt section. The revolver includes a connection unit having four optical transmission/receipt sections arranged at the intervals of 90 degrees in the circumferential direction of the revolver. All the transmission/receipt sections are spaced from the axis of the revolver by the same distance. When the revolver is brought to a stop at a preselected developing position, one of the four transmission/receipt sections of the revolver faces the transmission/receipt section of the apparatus body without fail. The connection units include a current transformer for feeding power from the apparatus body to the developing unit. The connection units face each other at parallel surfaces thereof.

Abstract: A color image forming apparatus for superimposing images formed on a plurality of photoconductive elements onto a copy sheet includes a sensor for reading a transfer member and a positional deviation detecting pattern formed on the transfer member, a memory for storing information relating to an area having no roughness, such as a scar, on the transfer member, a detector for detecting the area having no roughness on the basis of a signal read by the sensor and for causing the memory to store the information relating to the area, and a color deviation corrector for correcting color deviation on the basis of the signal generated by the sensor reading the positional deviation detecting pattern. The positional deviation detecting pattern is formed at an area of the transfer member having no roughness.

Abstract: An image forming apparatus which forms an image on a recording medium at a number of different dot densities.