Oki Data Corporation

Oki Electric Industry Co., Ltd.

Koji Ida

Hiroaki Sato

Hiroyuki Inoue

Akira Nagumo

Katsuyuki Ito

Masato Sakai

Shinichi Katakura

Shinichi Murakami

Kazuhiko Nagaoka

Yoshitatsu Okiyama

Noboru Otaki

Toyokazu Shiraishi

Yoshitaka Miyazaki

Koichi Negishi

Kenichi Ashida

Syuiti Fujikura

Shuichiro Ogata

Kimihide Ishizaki

An image forming apparatus includes an image forming unit that forms a developer image, a transfer portion that transfers the developer image to a transfer object, an endless transfer belt that rotates passing between the image forming unit and the transfer portion, a driving roller that drives the transfer belt to rotate, a plurality of marks provided on the transfer belt and arranged in a rotating direction of the transfer belt, a measurement unit that measures a rotation period of the transfer belt using the plurality of marks, and a controller that adjusts a timing at which the image forming unit forms the developer image, based on a measurement result of the rotation period measured by the measurement unit. A circumferential length L of the transfer belt in the rotating direction has a length based on a natural number multiple of a circumferential length m of the driving roller.

Image forming apparatus having transfer belt

An image forming apparatus according to the invention includes a plurality of image forming units and a changeover unit. The plurality of image forming units form multicolor images on an image carrier by overlapping, on a medium, developer images developed using developers. The changeover unit changes a layer overlapping sequence of the developer images on the medium. The developers include a developer emitting light according to radiation of non-visible light, and the changeover unit changes the layer overlapping sequence of the developer images using the developer emitting the light according to radiation of the non-visible light.

Image forming apparatus and image forming method for forming overlapping visible and non-visible images

A printer has a printing mechanism and a drive mechanism that drives the printing mechanism. The printing mechanism including a charging unit, a exposing unit, a photoconductive drum, a developing unit, and transfer unit. The drive mechanism includes a planetary gear that is selectively positioned depending on a direction of rotation thereof. The printer comprises a memory and a controller. The memory stores a first position of the planetary gear at which the planetary gear stops rotating. The controller determines a second position to which the planetary gear should be positioned when the planetary gear starts rotating after stoppage. The second position is determined depending on the direction of rotation in which the planetary gear starts rotating. The controller controls a timing at which a voltage is applied to the printing mechanism, the timing being determined in accordance with the first position and the second position. The timing includes a first timing and a second timing which lagging behind the first timing. The controller applies the voltage to the printing mechanism at the first timing if the second position is the same as the first position, and at the second timing if the second position is different from the first position.

Printer and a method of controlling the printer

An electrophotographic image forming apparatus in which an electrostatic latent image is formed on a charged surface of a photoconductive drum. The image is developed with toner into a toner image and the toner image is transferred to a recording medium. A charging roller is in contact with the photoconductive drum and charges the photoconductive drum when the charging roller receives a high voltage. A detector detects a characteristic such as an electrical resistance of the charging roller and outputs a signal indicative of the characteristic. A charging power supply applies a high voltage to the charging roller, the voltage having a value in accordance with the signal. A neutralizing device neutralizes the charged surface of the photoconductive drum before the detector detects the characteristic of the charging roller but does not neutralize the charged surface of the photoconductive drum when the electrostatic latent image is being formed.

Image forming apparatus including a charging power supply and a neutralizing device

An electrophotographic printer includes a transfer roller which rotates in contact with a cylindrical photoconductive drum. When print paper passes through a transfer point where the transfer roller is in contact with the photoconductive drum, a toner image on the photoconductive drum is transferred from the photoconductive drum to the print paper. A paper guide is disposed upstream of the transfer point with respect to a transport path of the print paper. The paper guide changes the direction of travel of the print paper so that the leading end portion of the print paper enters the transfer point in a direction substantially tangent to a circumferential surface of the photoconductive drum.

Print medium guide for electrophotographic printer

An image recording apparatus includes a rotating photosensitive drum, a developing unit, a neutralizing device, and a transferring device. An electrostatic latent image is formed on a charged surface of the rotating photosensitive drum, the electrostatic latent image being developed by a developing unit and subsequently transferred by a transferring device to a print medium. The neutralizing device neutralizes the charged surface of the photosensitive drum at the point on the surface disposed downstream of the developing unit and upstream of the transferring device with respect to rotation of the photosensitive drum. A controller controls the neutralizing device according to characteristics of the print medium such as size, material, insulation, and transparency. The neutralizing device may be operated in different modes. For example, the neutralizing device may neutralize an entirety of the charged surface of the photosensitive drum only if the print medium is of a predetermined characteristic, i.e., an insulating sheet such as a transparent OHP sheet or may neutralize only selected parts of the charged surface of the photosensitive drum according to a width of the print medium.

Image recording apparatus having a neutralizing device

An electrophotographic printer includes a rotating photoconductive drum, a developing unit, a transfer roller, and a neutralizer. The neutralizer neutralizes a second area of the surface of the photoconductive drum different from a second area in which the toner is applied. A sensor may be provided along the transport path to detect a leading end and a trailing end of the print medium passing along the transport path. In accordance with the sensor output, the neutralizer neutralizes the second area (i.e., top margin and bottom margin) on the photoconductive drum adjacent the leading end and the trailing end of the print medium. A neutralization data generator may be added. The neutralization data generator searches the bit map data for dots which should be printed, and produces neutralization data on the basis of the dots. Then, the neutralizer illuminates only the second area (i.e., areas in which toner is absent) in accordance with the neutralization data. The neutralization data generator inverts bit map data produced by a controller to produce the neutralization data and the neutralizer includes light emitting elements energized in accordance with the neutralization data to illuminated the area in which toner is absent. The neutralization data generator produces the neutralization data such that there is a buffer area surrounding the first area having a predetermined width. The buffer area is not neutralized.

Electrophotographic printer

A print head for non-impact printer is, for example, an LED head which comprises a plurality of light-emitting elements, LED drivers for selectively causing a drive current to flow into the light-emitting elements on the basis of the print data, a non-volatile memory for storing the modification data related to the value of the drive current. The modification data are determined in advance at the manufacturing process on the basis of the measured result when the light-emitting elements were driven by the LED driver so that all the light-emitting elements emit substantially same amount of light at the printing operation.

Non-impact printer and a print head thereof

A power supply for use in a printer provides a current progressively small with increasing transfer roller impedance. A reference current section RC sets a voltage Vr indicative of a reference current Ia of an output current Iout of the power supply PS. A voltage generator VG provides an output voltage Vout of the power supply PS. A voltage monitor VM monitors the output voltage to provide a voltage-monitoring signal Vm to an operational section E. The operational section E determines a correction value of the output current Iout on the basis of the voltage Vr and the voltage-monitoring signal Vm. The correction value is progressively small as the voltage-monitoring signal Vm increases. A current controller C controls the voltage generator VG in accordance with an operation result obtained by the operational section E, so that the transfer roller is supplied with a current progressively small with increasing roller impedance but is still charged to a voltage progressively high with increasing roller impedance.

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Tokyo, Japan

Koji Ida