Abstract: An image forming apparatus for transferring a toner image from an image carrier to a sheet-like recording medium by way of an intermediate transfer body is disclosed. A position on the intermediate transfer body where image formation should start is determined in accordance with the frequency of use of each of a plurality of regions defined on the intermediate transfer body. Specifically, one of the regions minimizing the sum of the frequencies of use of the regions is selected as the above position. The intermediate transfer body can therefore be evenly used over its entire circumference. While the intermediate transfer body is in a stand-by state, it is intermittently driven so as to be free from deformation.

Abstract: An image formation apparatus including first and second image formation sections each of which can form an image with at least two colors. A mark is provided on the intermediate transfer belt. This mark indicates a particular position on the belt. A belt mark sensor detects the mark on the belt. A timing instruction signal with which a timing of image formation is instructed to the first and second image formation sections is initialized each time the mark on the belt is detected.

Abstract: An image forming apparatus includes a common mount member formed with a shaft support portion for supporting a shaft supporting an image carrier and a writing device support portion for supporting the writing device. The common mount portion is affixed to a stationary member. The image carrier and writing device are held in a preselected positional relation via the common mount member. Also, a positional relation between the image carrier and a developing device is set via the common mount member. The image carrier and members surrounding it can be accurately assembled and adjusted in position with ease.

Abstract: An image forming apparatus using a plurality of laser beams having the same characteristic in order to form a predetermined color image. The predetermined color image consists of a plurality of image colors. The laser beams are shifted with respect to each other in a vertical scanning direction by a diameter of each laser beam divided by the number of the laser beams. Since a rotating of a polygon mirror which deflects the laser beams is asynchronous with a rotating of a photosensitive body on which each laser beam is radiated so as to form a latent image, image colors are shifted with respect to each other. According to the present invention, one of the laser beams is selected for each image color, based on a timing difference between the polygon mirror and the photosensitive body, so that image colors can be superimposed on each other.

Abstract: An image forming apparatus includes a semiconductor laser unit for emitting a laser beam, a photosensitive drum which rotates in a first direction, a scanning optical system for making the laser beam scan the photosensitive drum in a second direction perpendicular to the first direction, wherein an electrophotography process is carried out on the surface of the photosensitive drum, a data generator for generating intensity data for each dot in an image in accordance with image information supplied from an external controller, and a laser driver for outputting a driving signal which drives the semiconductor laser unit, the driving signal having a pulse width and a level for each dot in an image, the pulse width being a predetermined value less than a value corresponding to an interval between adjacent dots formed in a direction parallel to the first direction, and the level corresponding to the intensity data generated by the data generator.

Abstract: An image clock signal generating system generates an image clock signal which is used to enable and disable a scan of an optical scanner, and comprises a phase locked loop (PLL) circuit for generating an image clock signal in response to a reference pulse signal which comprises a plurality of pulses during a time corresponding to a scan range of the optical scanner and no pulses during a time corresponding to a no-scan range of the optical scanner. The PLL circuit includes a phase comparator which receives the reference pulse signal and a feedback signal and outputs a phase error signal dependent on a phase error between the two signals, a voltage controlled oscillator (VCO) for outputting an image clock signal, and an initial phase matching circuit for outputting the feedback signal in response to the image clock signal output from the VCO.

Abstract: A multipoint synchronization optical writing apparatus which carries out an optical writing through modulation of a writing beam from a first light source in accordance with image information, the modulation of the writing beam being made in synchronism with a picture element clock signal supplied based on a synchronizing beam from a second light source.

Abstract: A synchronizing signal generating system for a laser scanner comprises a source for emitting a first laser beam for scanning and a second laser beam for synchronization of scans by the first laser beam, a deflector for causing a scan of a medium by the first laser beam and a scan of a grating by the second laser beam, a converging optical system for converging the second laser beam transmitted through the grating, a light receiving system for receiving the second laser beam converged by the converging optical system and for generating a reference pulse signal, a circuit for controlling the source responsive to the reference pulse signal so as to synchronize a scan timing of the first laser beam and comprising a PLL circuit for generating a synchronizing signal which has a frequency N times a frequency of the reference pulse signal in response to the reference pulse signal and a control circuit for controlling a value of N depending on the recording density, and a driving circuit for driving the source of sync

Abstract: A synchronizing signal generating system for a laser scanner includes a source for emitting a first laser beam for scanning and a second laser beam for synchronization of scans by the first laser beam, a polygonal mirror for causing the first laser beam to scan a medium and for causing the second laser beam to scan a grating which has bright portions and dark portions alternately arranged along a scanning direction of the second laser beam, a converging optical system for converging the second laser beam transmitted through the grating, a light receiving system for receiving the second laser beam converged by the converting optical system and for generating a synchronizing signal and a circuit for controlling the source responsive to the synchronizing signal so as to synchronize a scan timing of the first laser beam. A scan length of the second laser beam measured on the grating is set longer than a scan length of the first laser beam measured on the same plane.

Abstract: A semiconductor laser control apparatus for controlling an optical output of a semiconductor laser comprises a correcting part supplied with a modulation signal which determines ON and OFF states of the semiconductor laser for outputting a processed modulation signal, and a driving circuit supplied with the processed modulation signal from the correcting part for supplying a driving signal to the semiconductor laser. The correcting part includes a differentiating circuit responsive to the processed modulation signal for supplying a correction signal having a predetermined time constant to the driving circuit when the semiconductor laser is ON so as to maintain the optical output of the semiconductor laser constant, and a pulse width correcting circuit for correcting a pulse width of the modulation signal to obtain the processed modulation signal.

Abstract: A synchronizing signal generating system for a laser scanner comprises a source for emitting a first laser beam for scanning and a second laser beam for synchronization of scans by the first laser beam, a polygonal mirror for causing the first laser beam to scan a medium and for causing the second laser beam to scan a grating which has bright portions and dark portions alternately arranged along a scanning direction of the second laser beam, a converging optical system for converging the second laser beam transmitted through the grating, a light receiving system for receiving the second laser beam converged by the converting optical system and for generating a synchronizing signal, and a circuit for controlling the source responsive to the synchronizing signal so as to synchronize a scan timing of the first laser beam. The converging optical system comprises a plurality of lenses or concave mirrors provided for a length corresponding to a scan length of the second laser beam on the grating.

Abstract: A semiconductor laser output control apparatus for controlling a drive current to be supplied to a semiconductor laser which is turned on and off so as to maintain a light output from the semiconductor laser at constant. At the rising edge when the semiconductor laser is turned on, constant current supplied from a constant current source to the semiconductor laser is corrected by correction current.

Abstract: A method for driving a Tandem carding machine provided with a fiber tufts supply means, a first and second carding machine, a first web transfer means disposed between the first and second carding machine, a second web transfer means for transferring a continuous web to a coiler motion mechanism, in which the lickerin roller, carding cylinder and a flat mechanism of the second carding machine are driven by a second driving motor while the other rotating elements are separately driven by a first driving motor. To control the sequential motion of the above-mentioned two series of driving mechanisms, said first and second driving motors are electrically connected.