Oki Data Corporation

Zenji Takahashi

Hiroyuki Yajima

An invented image forming apparatus includes a fixing unit for fixing a developer image transferred onto a conveyed medium; a temperature detecting unit for detecting a temperature of said fixing unit, a first power supply controller for controlling power supply to said fixing unit based on the detected result of the temperature detecting unit, a second power supply controller for controlling power supply to said fixing unit based on a preset value, a medium detection unit for detecting a medium to be conveyed, and a power supply operation controller for switching control done between said first power supply controller and said second power supply controller based on a position of the medium detected with said medium detection unit. The image forming apparatus can reduce impairment of settling rate of the developer images at the second half of the recording paper during the fixing process.

Information forming apparatus having a variable power fixing unit

After a skew of a sheet as a recording medium is corrected by correcting a sheet curve, exposure writing on a photosensitive drum is started synchronously with re-driving of resist rollers. When a sheet front edge is detected by a sensor, sheet conveyance is continued while adjusting a sheet conveying speed when an exposure start position reaches a transfer position at a pressure contact point between the drum and a transfer roller, thereby adjusting the time of arrival at the transfer position. A time/distance interval between the preceding and subsequent sheets are shortened, a conveying path is shortened, and the whole apparatus is miniaturized. Print processing efficiency is raised and stable printing without a variation is executed. A transfer start position of the sheet is made to accurately coincide with the exposure start position of the drum, thereby realizing a high print processing speed.

Image recording apparatus and its control method

The transfer voltage supplied to the transfer roller in an electrophotographic printer is determined by feeding current to the transfer roller and reading the voltage produced by passage of the current through the transfer roller. Whether the transfer roller is adequately charged is determined by comparing the voltage reading with a previous voltage reading. The voltage reading is preferably an average reading taken over one revolution of the transfer roller. Alternatively, separate voltage readings are taken for different radial sectors of the transfer roller, and the transfer voltage is determined separately for each radial sector.

Electrophotographic printer determining transfer voltage from voltage

An apparatus controls a temperature of a heat roller for fixing a developer material transferred on a print medium such as paper. The apparatus includes a controller, a sensor for detecting the thickness and/or width of a print medium such as paper, and a temperature-detecting element such as a thermistor for detecting the temperature on a first surface of the heat roller outside of a second surface area of the heat roller in contact with the print medium. The controller controls the temperature of the heat roller in accordance with the dimension of the print medium so that the middle portion of the heat roller is maintained substantially at a temperature of a first predetermined value during continued printing operation. The controller raises the temperature on the first surface stepwise in accordance with each page of the print medium during continued printing operation till the temperature on the first surface reaches a temperature of a second predetermined value, and maintains thereafter the temperature on the first surface at the second predetermined value during continued printing operation.

Growing community of inventors

Tokyo, Japan

Zenji Takahashi