Abstract: A plurality of first base images for a base color are formed in accordance with a predetermined adjustment value. A plurality of first correction images for a correction color to be a subject for correction are formed on the first base images in accordance with a predetermined adjustment value. The first correction images are displaced within a predetermined range. The first adjustment value is determined from changed adjustment values. The second base images for the base color are formed in accordance with the predetermined adjustment value while the second correction images for the correction color are formed in accordance with a plurality of adjustment values determined based on the first adjustment value. One second adjustment value having an extreme is determined from the plurality of adjustment value candidates. These processes are repeated to determine a final adjustment value. The adjustment value for the correction color is corrected to the determined final adjustment value.

Abstract: Each of a plurality of combined images is formed separately for each image carrier with respect to a length related to the circumference length (Dp×&pgr;) of the image carrier. There is provided a combined-image adjusting section for forming a combined image so that a density detecting section detects the density of the combined image at plural and substantially equal pitches within a range of at least one circumference length (Dp×&pgr;) of the image carrier, or so that the density detecting section detects the density average value of the combined image at plural and substantially equal pitches within a range of at least one circumference length (Dp×&pgr;) of the image carrier.

Abstract: An image adjustment method for an image forming apparatus in which an adjustment image is formed by transferring a plurality of reference images formed by a color component to be the reference among a plurality of color components and a plurality of images to be adjusted, which are formed by other color component to be adjusted, onto a transfer medium so that the images to be adjusted are superposed on the reference images, the density of the formed adjustment image is detected, and an image forming position of the other color component to be adjusted is adjusted based on the detected density of the adjustment image. The density of the surface of the transfer medium is detected, and the position of forming the image to be adjusted is adjusted, based on the detected density of the surface of the transfer medium and the detected density of the adjustment image.

Abstract: Images based on each of a plurality of color components are formed; the formed images are transferred on each transfer medium to form an image quality determining image; the image quality of the image quality determining image is determined on the basis of the detected density thereof, an adjustment image is formed by overlaying and transferring an image of other color component to be adjusted to the reference image of the reference color image out of the plurality of color components, on the transfer medium; the density of the adjustment image is detected; and the image forming position of the other color component to be adjusted is adjusted on the basis of the detected density.

Abstract: Focus adjustment of an optical writing unit is performed based on an image of a test pattern formed on a paper sheet. The pattern includes bars of density levels associated with adjustment quantity information indicating numerical values corresponding to the numbers of rotation of adjustment motors and adjustment screws. The density levels decrease as the amount of displacement of the unit with respect to a photosensitive drum increases. A focus adjustment device accepts an input of the numerical values indicated beside the unprinted bars of the lowest density levels and causes the motors to turn by the numbers of rotation indicated by the input numerical values to move the unit to the position of correct focus. It is possible to perform focus adjustment of the unit with ease and high accuracy regardless of whether the unit is for forming binary or multi-valued images.

Abstract: Assuming the photosensitive drum for black as a reference, the phase of the adjacent photosensitive drum for cyan leads by about 60 deg. Similarly, the phase of the photosensitive drum for magenta leads by about 120 deg., and the phase of the photosensitive drum for yellow leads by about 180 deg. The phase of each photosensitive drum is shifted to thereby make it possible to shift the phase of driving unevenness. By shifting the phase, even the distance between adjoining transfer positions corresponding to the image forming stations is set shorter than the circumference of the photosensitive drum, the variation of each photosensitive drum due to driving unevenness with respect to the printing medium passing through the transfer position can be kept congruent with the others.

Abstract: The image forming apparatus includes: an image data input section for reading a document as image data; a target value memory section for storing a target value of an input/output characteristic value when a reference document is read; a comparator for comparing the image data of the reference document and the target value so as to create a new input/output characteristic value; a fixed value memory section for storing a difference in input/output characteristic values as a fixed value between an original document and a copy document; and an adder for adding the fixed value to the image data of the reference document so as to output a resultant value to the comparator. By the provision of the fixed value memory section and the adder, the image forming apparatus can set a plurality of input/output characteristic values by reading the reference document once, thus reducing time for the procedure of setting the respective input/output characteristic values.

Abstract: An object of the invention is to reproduce a faithful image irrespective of thermal expansion of a light-scanning unit and to reproduce a faithful image without enhancing the strength of the light-scanning unit excessively. A pair of supporting portions of a light-scanning unit, each having a flat face, are supported in linear contact with a right column-shaped supporting member provided with the apparatus body. The light-scanning unit is provided on the supporting member near to a starting position where writing image data on a photosensitive body with a scanning line is started in a main scanning direction so as not to be mutually displaced relative to the supporting member. Thereby, the light-scanning unit is allowed to extend in the longitudinal direction of the supporting member due to thermal expansion of the light-scanning unit.

Abstract: A color image apparatus which has a cooling arrangement to help prevent a plurality of light-scanning units for respective colors therein from being adversely influenced by heat from a thermally fixing unit within the apparatus. In a space portion where all light-scanning units are housed, an air-exhausting fan is provided in the vicinity of the light-scanning unit nearest to the thermally fixing unit, and an air hole is formed at a position farthest from the thermally fixing unit. Additionally a temperature sensor is mounted on the light-scanning unit nearest to the thermally fixing unit. Rotation speed of the air-exhausting fan is controlled so that the temperature detected by the sensor does not exceed a predetermined temperature limit.

Abstract: In an optical scanning device for forming an electrostatic latent image on an image-bearing body with scanning beam released from a light source, a support body having a plurality of supporting faces and first and second optical means for directing the scanning beam from the light source onto the image-bearing body are installed. Moreover, in the support body, a light transmitting means for transmitting the scanning beam from the first optical means to the second optical means is installed in the vicinity of a ridge portion thereof that is the least susceptible to deformation and distortion and strongest in its strength. Thus, it becomes possible to improve a light image in its precision that is formed by the scanning beam directed onto the image-bearing body.

Abstract: A registration pattern data generating portion is configured of a pattern set data generator for rough order error estimation and a pattern set data generator for fine order error estimation. When an error is estimated, a pattern set for rough order error estimation is checked first so as to roughly determine the size of the error and then another pattern set for fine order error estimation is checked so as to finely determine the size of the error. Thus, checking the two types of pattern sets makes it possible to exactly recognize the error in rough and fine units, providing fast and exact error determination.

Abstract: In an image forming apparatus wherein a multiple number of image supports form developer images of different colors so that the developer images of different colors corresponding to the multiple number of image supports are superimposed to a recording medium to form an image, flywheels are set at the ends of the rotary shafts of multiple image supports corresponding to relatively highly visible colors while no flywheel or a flywheel having a different diameter or weight from that of the above is set for the image support corresponding to a less visible color so as to make the inertial condition different from that of the others.

Abstract: The image processing circuit essentially includes an image data input portion, an image processing portion, an image data output portion, an image memory composed of a hard disk drive etc., a central processing unit (CUP), an image editing portion, an external interface portion. Based on the determination result of the laser recording status determination by the CPU, an LCU also serving as a mirror motor control device, stops or retards the drives of driving motors, one by one, in the order of their completion of laser recording. The image processing circuit may further has a mode manager for checking the usage frequencies of the first most processing mode in which the input image information is image processed as color image information and the second processing mode in which the input image information is processed as monochrome image information. Moreover, the image processing portion may further has an original discriminating portion for determining the color type of an original.

Abstract: An object of the invention is to provide an image forming apparatus in which a unit can be attached to the apparatus body in a status where a correct positional correlation between a photoconductive drum and each of other process devices mounted on a unit is maintained. A photoconductive drum is positioned within a copier body by a rotating drive shaft, and the other process devices mounted on a process unit are positioned within a copier body by a boss and a locking member. The boss positions the rotating drive shaft within the copier body. Since the locking member is fitted onto a front-side end of the rotation drive shaft, the locking member is positioned within the copier body by the rotating drive shaft. The other process devices mounted on the process unit are positioned within the copier body by the rotating drive shaft via the boss and the locking member.

Abstract: In this digital color copier, laser beam scanner units of the same configuration are arranged in parallel with each other, and all are controlled in a unified manner by a laser control unit provided outside the units. In order to synchronously rotate the polygon mirrors in a precise manner, the speeds of rotations of their motors, fed back from tacho-generators are compared to the reference frequency generated from an oscillator so as to allow a motor control circuit to control the driving motors of the polygon mirrors. Further, the BD signals from beam detectors (BD) are fed back to the laser control unit so that all the BD signals from the laser scanner units for black and the three colors can become synchronized with each other, thus enabling control of the polygon mirrors.

Abstract: An image forming apparatus has a locking mechanism and a detecting switch. The locking mechanism locks a drive mechanism not to drive a waste toner container when no waste toner container is loaded in a predetermined place, and releases and thus allows the drive mechanism to drive the waste toner container when the waste toner container is loaded in the predetermined place. The detecting switch outputs, in response to the locking mechanism, a detection signal which varies depending on whether the waste toner container is loaded in the predetermined place. A transporting mechanism for transporting waste toner to the waste toner container is also locked in linkage with the locking mechanism. Consequently, the image forming apparatus has a simple structure and is low-cost and free from faulty operations in judging whether the waste toner container is loaded in the predetermined place and in preventing a faulty transportation of the waste toner to the waste toner container.

Abstract: The object of the present invention is to provide a paper pressing mechanism which performs feeding of curling sheets with a simple and compact structure. In order to realize the object, the paper pressing mechanism comprises a driving shaft 19; a paper pressing roller 15; a paper pressing arm 11 provided at both ends thereof with paper pressing portions 12, 13; and a supporting arm 17, axially supported in a rotatable manner at its one end by the driving shaft 19, and holding at the other free end the paper pressing roller 15 and the supporting arm 17 in a rotatable manner; and is characterized in that the supporting arm 17 is driven by the driving shaft 19 between a retracted position in which the mechanism is kept away from sheets of paper on a sheet table and a pressing position in which the sheets are pressed by both the paper pressing roller 15 and paper pressing portions 12,13 at the ends of the paper pressing arm 11.