Canon Kabushiki Kaisha

Junichi Noguchi

Yushi Oka

Takayuki Kawakami

Yoshitaka Yamazaki

Akihito Mori

Naoto Yamada

Hajime Motoyama

Hajime Kaji

Satoshi Ogawara

Kiyoshi Okamoto

Shinichi Takata

Takashi Soya

Shigemichi Hamano

Tomoichiro Ohta

Takashi Kanno

Katsumi Takahashi

Yoritsugu Maeda

An image forming apparatus includes a scanner motor and a rotary polygonal mirror which is driven by the scanner motor to rotate, and reflects a modulated beam emitted from a light source by a plurality of reflection surfaces. The image forming apparatus includes a rotation and carrier unit which, while rotating, carries an image formed on the basis of a laser beam reflected by the rotary polygonal mirror, a speed detection unit which detects a rotation speed of the rotation and carrier unit. The image forming apparatus includes a tracking characteristic detection unit which detects a tracking delay of the scanner motor from a target rotation speed and a control unit which controls, on the basis of the rotation speed detected by the speed detection unit and a tracking characteristic detected by the tracking characteristic detection unit, a rotation speed of the scanner motor that drives the rotary polygonal mirror.

Adjusting the speed of a scanner motor in an image forming apparatus

Adjustment processing is suitably executed in accordance with the type of post processing. To accomplish this, an image forming apparatus includes, for example, an adjustment part, specifying part, and control part. The adjustment part performs at least one of adjustment operation for an image formation position and adjustment operation for an image formation density by forming adjustment patterns using a developing material on an image carrier and measuring the adjustment patterns. The specifying part specifies the size of an image to be formed on a sheet and the content of post processing in case of executing a job which requires post processing on the sheet. The control part controls, in accordance with the size of the image and the content of the post processing, whether to perform the adjustment operation by the adjustment part concurrently with the formation of an image made from a job requiring post processing.

Image forming apparatus including adjustment processing and control method therefor

A technique for reducing downtime that accompanies the execution independently of adjustment processing for maintaining image quality and the execution of finishing processing relating to a printing medium. In order to apply the finishing processing to the printing medium in a finishing processing unit, an image forming apparatus to which this technique is applied sets a time between sheets that extends from end of image formation regarding a first sheet of the printing medium to start of image formation regarding a second sheet of the printing medium transported following the first sheet of the printing medium in the image forming unit, and executes adjustment processing, which is for maintaining image quality in the image forming unit, within the set time between sheets.

Image forming apparatus for executing adjustment processing and finishing processing

An image forming apparatus forms an image by scanning on a photosensitive member in the main-scanning direction with a plurality of beams aligned in the sub-scanning direction. To detect differences in the main-scanning length of each beam on a photosensitive member, patterns for correction are formed on the photosensitive member using first and second beams at both ends among the plurality of beams. The positions of a first pixel and a last pixel in the main scanning direction on the photosensitive member, which pixels are to be formed by a third beam arranged between the first and second beams, are determined based on the detected first and second locations of the first and second test patterns respectively formed by the first and second beams, without forming a third test pattern by the third beam.

Image forming apparatus and control method thereof having main scan length correcting feature

An image heating apparatus comprises an endless belt for heating an image on a recording material. A heating member is provided for heating a part of the endless belt and a contact member is provided for contacting an inner surface of the belt. A stand-by control unit is operable in a stop period in which the heating member effects heating with the belt at rest and in a rotation period in which the belt is rotated, and a drive stop control unit is provided for stopping the endless belt at a position that the contact member contacts at least a part of a portion of the endless belt that has been opposed to the heating member in a previous stop period.

Image heating apparatus and image forming apparatus

Disclosed is an image forming apparatus whereby waiting time (downtime), which is required for forming an image by automatic adjustment relating to image formation density or image formation position, is made shorter than in the prior art. When an image having a size equal to or less than a prescribed size is formed is formed in this apparatus, the image to be formed is placed on an image carrier in such a manner that a vacant area for forming an adjustment pattern can be reserved on the image carrier. As a result, automatic adjustment relating to image formation density or image formation position can be executed while an image is formed.

Image forming apparatus having image placement control and method of controlling same

An image forming apparatus which can improve image formation capability to a satisfactory degree while curbing the rise in running cost. An image forming device forms adjustment images having different densities on an image support member having a higher optical reflectivity than an optical reflectivity of the adjustment images. A reading reads the adjustment images. An output from the reading device is read at a predetermined number of readings or time interval between readings based on the densities of the adjustment images susceptible to the optical reflectivity of the image support member.

Image forming apparatus that forms adjustment images having different densities and image forming method of controlling the image forming apparatus

An image forming apparatus generates a PWM signal corresponding to input image data and controls a timing of a light source to emit a light beam based on the PWM signal in order to perform tone reproduction. The image forming apparatus includes a data processing unit configured to generate the PWM signal for one pixel based on image data for continuous two pixels in the image data. The data processing unit selects an origin of pulse growth in generation of the PWM signal for one pixel in accordance with the image data for the two pixels to generate the PWM signal.

Image forming apparatus and image forming method

An image forming apparatus includes an intermediate transfer member position detection unit configured to detect a position of the intermediate transfer member to output an image forming operation start signal, a pattern detection unit configured to detect a registration correction pattern formed on the intermediate transfer member based on the image forming operation start signal, a misregistration variation detection unit configured to read the registration correction pattern detected by the pattern detection unit based on the image forming operation start signal and to generate a reference clock signal based on the read registration correction pattern, and a polygonal mirror drive motor control unit configured to adjust a rotation speed of the polygonal mirror drive motor based on the reference clock signal generated by the misregistration variation detection unit.

Image forming apparatus

To detect differences in the main-scanning length of each beam on a photosensitive member, patterns for correction are formed on the photosensitive member using only beams (L, LN) at both ends among a plurality of beams aligned in a sub-scanning direction. The patterns are transferred onto an intermediate transfer belt and detected with photosensors, a difference &#x394;LN of scanning length between a 1-st line and a N-th line is calculated, and a difference &#x394;Li of scanning length of a i-th line is calculated by &#x394;Li=&#x394;LN&#xd7;(i/N&#x2212;1) so as to proportionally distribute &#x394;LN to the i-th line. The scanning lengths of lines are respectively corrected to be equal each other using the obtained differences &#x394;Li of scanning length. Thus, an image forming apparatus and a control method that reduce a decline in image quality, even when scanning incident angles of laser beams onto a photosensitive member differ for each of beams on forming images by scanning a multiple lines with a multiple beams, can be provided.

An image formation device changes the rotational rate of a polygon motor, i.e. the main-scanning rate, and selects one of pulse width conversion tables when an image formation is performed multiple times on a single sheet of transfer paper. The changing of the main-scanning rate is for preventing inconsistent sizes between a first recorded image and a second recorded image caused by shrinkage of transfer paper. The pulse width conversion tables allow the pulse widths to be modulated.

Image formation device

An image forming apparatus which is capable of eliminating density irregularities of an image formed caused by potential irregularities of the photosensitive member when the drum is irradiated by a beam of constant luminous intensity. A laser driver irradiates a beam modulated based on an image signal onto a photosensitive member. A current controller variably controls a driving current for driving the laser driver. A PWM pulse width converter modulates a pulse width of the beam based on the image signal. A potential sensor measures the potential of the photosensitive member after the photosensitive member is irradiated by a beam having a predetermined luminous intensity. A selector causes the current controller to correct the driving current based on low frequency components of irregularities of the potential and changes a modulation coefficient used for modulating the pulse width based on high frequency components of the irregularities of the potential.

Image forming apparatus, control method therefor, and program for implementing the control method

An image forming apparatus for forming an image by modulating laser light in correspondence with an image signal. A pulsewidth modulation signal is generated in correspondence with input image data. A laser drive control circuit has a photosensor PD which detects laser light emitted from a laser diode LD and generates a detection current, a resistor which generates a detection voltage corresponding to the detection current outputted from the photosensor PD, a buffer in which the generated detection voltage is inputted, an amplifier which amplifies an output from the buffer, and a constant current source and a switch to add a predetermined current to the detection current for compensation for reduction of output voltage due to offset voltages of the buffer and the amplifier. Control data for controlling maximum and minimum pulsewidths in the pulsewidth modulation signal are obtained based on the detection voltage, and generation of the pulsewidth modulation signal is controlled.

Image forming apparatus and laser drive control method therein

Images are efficiently formed from a plurality of originals at a high speed. A first original and a second original simultaneously disposed on an original-mount are scanned by relative movement of an illuminating unit with respect to the first original and the second original. An image corresponding to the first original is borne at forward scanning with respect to the original-mount, and an image corresponding to the second original is borne at backward scanning with respect to the original-mount. An image corresponding to the first image and an image corresponding to the second image are formed on a first recording medium and a second recording medium, respectively. An image signal corresponding to the second original is sequentially stored in a storage medium in accordance with the scanning. The stored image signal is read from the storage medium in a sequence reverse to a sequence of the storage.

Growing community of inventors

Suzhou, China

Junichi Noguchi