Method and device for correcting a position for writing an image
AssigneeRicoh Company, Ltd.
InventorsNoboru Sawayama, Takashi Mama
Life of this patent
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Abstract
In an image forming apparatus, a method of correcting a position for writing an image on a photoconductive element on the basis of a signal representative of a pattern formed on the element and detected, and a device therefor. A single photoconductive element is used to form a plurality of different colored images using a single rotating polygonal mirror and a plurality of light sources. The toner images can be sensed either while they are on the single photoconductive element or by sensing them through a transport belt.
Claims18
A device for correcting a position for writing an image on a photoconductive element included in an image forming apparatus, said device comprising:
- pattern forming means for forming a predetermined pattern image in a non-image area of the photoconductive element;
- pattern sensing means for optically reading said pattern image;
- and
- writing position adjusting means for adjusting an image writing position in response to an output signal of said pattern sensing means representative of said pattern image,
- wherein said pattern image comprises a rectangular pattern longer in a main scanning direction than in a subscanning direction, an image write signal being controlled such that a target image forming position of one edge of said rectangular pattern extending in a vertical direction coincides with a center of a sensing range of said pattern sensing means.
A device for correcting a position for writing an image on a photoconductive element included in an image forming apparatus, said device comprising:
- pattern forming means for forming a predetermined pattern image in a non-image area of the photoconductive element;
- pattern sensing means for optically reading said pattern image;
- and
- writing position adjusting means for adjusting an image writing position in response to an output signal of said pattern sensing means representative of said pattern image,
- wherein said pattern image comprises a Z-shaped pattern, an image write signal being controlled such that a target image forming position of a center line of said Z-shaped pattern coincides with a center of a sensing range of said pattern sensing means.
A device for correcting a position for writing an image on a photoconductive element included in an image forming apparatus, said device comprising:
- pattern forming means for forming a predetermined pattern image in a non-image area of the photoconductive element;
- pattern sensing means for optically reading said pattern image;
- and
- writing position adjusting means for adjusting an image writing position in response to an output signal of said pattern sensing means representative of said pattern image,
- wherein said pattern image comprises a density pattern whose density changes in a main scanning direction, an image write signal being controlled such that a target image forming position of particular part of said density pattern coincides with a center of a sensing range of said pattern sensing means.
A method of correcting a position for writing an image on a photoconductive element included in an image forming apparatus, said method comprising the steps of:
- a) writing a plurality of images of different colors on the photoconductive element by optical writing means to electrostatically form corresponding latent images;
- b) developing each of the latent images by a toner of particular color by developing means to form a corresponding toner image;
- c) illuminating the resulting toner images and sensing reflections from said toner images by an optical sensor;
- and
- d) correcting a position for writing an image on the photoconductive element by said optical writing means on the basis of the sensed reflections,
- wherein said step of writing a plurality of images of different colors on the photoconductive element includes:
- writing the plurality of images of different colors on the photoconductive element which is a single photoconductive element for the plurality of images of different colors.
An image forming system comprising:
- a rotating polygonal mirror;
- two light sources which reflect light off of the rotating polygonal mirror;
- a single photoconductive element;
- a first charger for charging the single photoconductive element;
- a first developer for developing a first latent image on the single photoconductive element, formed by a first of the two light sources, into a first toner image of a first color;
- a second charger for charging the single photoconductive element having the first toner image thereon;
- a second developer for developing a second latent image on the single photoconductive element, formed by a second of the two light sources, into a second toner image of a second color;
- at least one pattern sensor for sensing the first and second toner images;
- and
- a correction device, connected to the at least one pattern sensor, which corrects a position where at least one of the first and second light sources form latent images using a relationship in positions between the first and second toner images,
- wherein said first and second developers develop the first and second toner image to at least partially overlap each other.
In an image forming apparatus in which a plurality of writing means, each being assigned to a particular color, form respective latent images on an image carrier and develop the respective latent images with toner of respective colors, a method of automatically adjusting writing positions of said plurality of writing means, comprising the steps of:
- causing two of said plurality of writing means to form toner patterns for position adjustment of the respective colors;
- sensing with an optical sensor changes in quantities of light reflected from or transmitted through the toner patterns of two different colors by sensing a relationship in positions between the toner patterns;
- and
- adjusting write start positions of the two writing means such that the toner patterns are formed at a position where an output of said optical sensor is one of a maximum and a minimum,
- wherein said step of causing two of said plurality of writing means to form toner patterns form the two toner patterns which at least partially overlap each other.
A method of correcting a position for writing an image on a photoconductive element included in an image forming apparatus, said method comprising the steps of:
- a) writing a plurality of images of different colors on the photoconductive element by optical writing means to electrostatically form corresponding latent images;
- b) developing each of the latent images by a toner of particular color by developing means to form a corresponding toner image;
- c) illuminating the resulting toner images and sensing reflections from said toner images by an optical sensor;
- and
- d) correcting a position for writing an image on the photoconductive element by said optical writing means on the basis of the sensed reflections,
- wherein the reflections are total reflections.
A method of correcting a position for writing an image on a photoconductive element included in an image forming apparatus, said method comprising the steps of:
- a) writing a plurality of images of different colors on the photoconductive element by optical writing means to electrostatically form corresponding latent images;
- b) developing each of the latent images by a toner of particular color by developing means to form a corresponding toner image;
- c) illuminating the resulting toner images and sensing reflections from said toner images by an optical sensor;
- and
- d) correcting a position for writing an image on the photoconductive element by said optical writing means on the basis of the sensed reflections,
- wherein the toner images are each provided with a greater dimension in a direction perpendicular to a direction for adjusting the position for writing than a dimension of a sensing range of said optical sensor in said direction perpendicular to said direction for adjusting.
A method of correcting a position for writing an image on a photoconductive element included in an image forming apparatus, said method comprising the steps of:
- a) writing a plurality of images of different colors on the photoconductive element by optical writing means to electrostatically form corresponding latent images;
- b) developing each of the latent images by a toner of particular color by developing means to form a corresponding toner image;
- c) illuminating the resulting toner images and sensing transmitted light from said toner images by an optical sensor;
- and
- d) correcting a position for writing an image on the photoconductive element by said optical writing means on the basis of the sensed transmitted light,
- wherein the transmitted light is diffused transmitted light.
A method of correcting a position for writing an image on a photoconductive element included in an image forming apparatus, said method comprising the steps of:
- a) writing a plurality of images of different colors on the photoconductive element by optical writing means to electrostatically form corresponding latent images;
- b) developing each of the latent images by a toner of particular color by developing means to form a corresponding toner image;
- c) illuminating the resulting toner images and sensing transmitted light from said toner images by an optical sensor;
- and
- d) correcting a position for writing an image on the photoconductive element by said optical writing means on the basis of the sensed transmitted light,
- wherein the toner images are provided with a greater dimension in a direction perpendicular to a direction for adjusting the position for writing than a dimension of a sensing range of said optical sensor in said direction perpendicular to said direction for adjusting.
Dependencies are inferred from the claim text.