Canon Kabushiki Kaisha

Hiroki Tezuka

Yoichiro Maebashi

Tomoaki Nakai

Hiroshi Kita

Hiroyuki Yamazaki

Seiji Uchiyama

Hiroki Kitamura

Toshiki Nakayama

Yoshiyuki Akiba

Yasuo Kizaki

Yoichicro Maebashi

A calibration method for calibrating a color image forming apparatus includes detecting the color of a patch formed on a recording medium by the color image forming apparatus using a color sensor, converting a detected color signal in a first color specification system into a color signal in a second color specification system, and adjusting at least one of the image forming conditions for the color image forming apparatus, based on the color signal converted in the conversion step, where the conversion conditions in the color signal conversion are different depending on the attributes of the patch.

Method for calibrating color image forming apparatus

Patches of black and a mixture of color coloring materials are formed on a recording medium, and the chromaticities of the patches are detected (S). Black tonality data serving as reference lightnesses corresponding to respective tonality data are acquired from pieces of lightness information contained in the detected chromaticities corresponding to the respective tonalities of the black patches. Pieces of black lightness information are corrected on the basis of the acquired black tonality data and the detection results of the black patches. Chromaticities corresponding to the black tonality data are defined as target chromaticities, and the mixture rates of the color coloring materials are corrected on the basis of the target chromaticities and the chromaticities obtained by detecting the patches using the color coloring materials.

Color image forming apparatus and control method therefor

A color image forming apparatus includes a coordinate conversion part, which converts a ordinate value, for executing a misregistration correction in the unit of a pixel; a gradation conversion part, which converts a gradation level, for executing a misregistration correction in a unit less than a pixel; and a judgment part, which detects a feature of the image and judges whether or not to execute the misregistration correction in a unit less than a pixel by the gradation conversion part. The judgment part compares the gradation level in an object pixel and a pixel adjacent in a sub-scanning direction, thereby judging whether or not to execute the misregistration correction in a unit less than a pixel. Thus, the invention enables to distinguish an image to be subjected to the registration correction in a unit less than a pixel and an image not to be subjected to such correction in a simple manner and also in consideration of the image color.

Color image forming apparatus

In a color image forming apparatus, a user need not exchange a sensor, paper is prevented from being wastefully consumed, and image quality and color reproducibility can be improved. The color image forming apparatus includes a detecting unit which detects the density or chromaticity of a test image formed on a recording medium, and a correction unit which corrects the density or chromaticity of the image by using the detection result obtained by the detection unit. The detection units are arranged in the first direction perpendicular to the convey direction of the recording medium.

Image forming apparatus with reduced paper consumption

Provided are a method of making correction for color sensor output values in color image forming apparatus, which succeeds in improving color reproducibility of the color image forming apparatus, and the color image forming apparatus provided with the method. For this purpose, the apparatus and method according to the present invention make correction for deviation due to a color detecting device, of a color sensor output value Sin detection of a fixed patch; set a boundary turning point D between an ignorable region of toner bearing amounts where the influence of a color of a transferring material is ignorable on chromaticity of the patch and an unignorable region of toner bearing amounts where the influence is unignorable; make further correction for a corrected value S'after the correction for the deviation due to the color detecting device, using different methods for the unignorable region and the ignorable region, thereby to eliminate the influence of the color of the transferring material on the chromaticity of the patch.

Method of making correction for color sensor output values in color image forming apparatus, and color image forming apparatus

A color image forming apparatus and related method forms a color image on a transfer material. The apparatus is provided with a first optical sensor capable of detecting optical reflection characteristics of an unfixed toner image and a second optical sensor capable of detecting optical reflection characteristics of a toner image after fixation. A first forming step forms a mixed-color toner image including plural toners. A calculation step calculates, based on optical reflection characteristics of the mixed-color toner image detected by the second optical sensor, a condition that the mixed-color toner image becomes achromatic. A second forming step forms a toner image corresponding to the calculated toner mixing ratio. A processing step processes an output of the first optical sensor based on the optical reflection characteristics of the monochromatic toner image detected by the first optical sensor.

An image forming apparatus is provided in which, by detecting an image formed on a recording medium, at least one of the density and chromaticity of the image can be properly controlled. The image forming apparatus includes an image forming unit for forming a toner image on an image carrier, a transfer unit for transferring the toner image formed by the image forming unit onto a transfer material in a transfer position, a fusing unit for fusing the toner image transferred by the transfer unit on the transfer material, a feed-direction changing unit for changing over a feed direction of the transfer material so that the transfer material having the toner image fused by the fusing unit is reversed and fed to the transfer position, a detecting unit for detecting, in a predetermined detecting position, the toner image fused on the transfer material by the fusing unit, and a control unit for controlling the image forming unit based on result detected by the detecting unit.

Image forming apparatus which performs image formation control based on the image after fixing

A color image forming apparatus includes a first density detecting unit for detecting a density of a first detection toner image formed on an image bearing member or a transferring material carrying member, and a second density detecting unit for detecting a density of a second detection toner image fixed onto a transferring material, and executes image density control based on a detection result of the first density detecting unit and a detection result of the second density detecting unit. A detecting light application position of the first density detecting unit and a detection light application position of the second density detecting unit are almost equal relative to a perpendicular direction to a transferring material conveying direction. It is thereby possible to shorten time required for density control and to prevent deterioration of density control accuracy caused by a temporal change and a positional change in the density of a detection toner patch.

Color image forming apparatus and method for controlling the same

In a color image forming apparatus, a color toner patch for controlling density or chromaticity may be detected by a color sensor and fed back to process conditions so as to control density or chromaticity of a final output image. However, a white reference board for proofreading sensor output is expensive, and may have paper powder, toner or ink scattered thereon to become no longer usable as a reference board. The present invention provides a color identification method and a color image forming apparatus exploitable for density or chromaticity control by using a color sensor without using the reference board. In the present invention, a gray patch of black and a process gray patch of yellow, magenta and cyan are formed on a transfer medium, the chromaticity is detected without using a criterion for sensor output proofreading, and relative comparison is made between the chromaticities detected from the above two types of gray patches by using as a standard the gray patch of black which is almost achromatic, and if the chromaticities are consistent with each other, the process gray patch is judged to be achromatic.

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Kanagawa, Japan

Hiroki Tezuka