# US 7,613,408 B2 · Image forming apparatus for correcting image formation condition

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- Number: US 7,613,408 B2
- Document ID: US7613408B2
- Status: Granted
- Kind: B2
- Application number: 11/535,593
- Filed: 2006-09-27
- Published: 2007-04-05
- Granted: 2009-11-03
- Earliest claimed: 2005-09-30
- Assignees: Brother Kogyo Kabushiki Kaisha
- Inventors: Minoru Karasawa; Yukimasa Yoshida
- Web page: https://patentgrep.com/patent/US7613408B2

## CPC

- G03G 15/065: {Arrangements for controlling the potential of the developing electrode}
- G03G 15/5058: {using a test patch}
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY

## Abstract

An image forming apparatus includes: an image forming unit that forms an image by forming an electrostatic latent image on an image carrying body, developing the electrostatic latent image by sticking a developer on the image carrying body, and transferring the developer to a recording subject medium; a suspension time calculating unit that calculates a suspension time for which image formation by the image forming unit is suspended; and a correction amount calculating unit that calculates a correction amount for an image formation condition of the image forming unit based on the suspension time calculated by the suspension time calculating unit.

## Claims

### Claim 1

An image forming apparatus according comprising:
an image forming unit that forms an image by forming an electrostatic latent image on an image carrying body, developing the electrostatic latent image by sticking a developer on the image carrying body, and transferring the developer to a recording subject medium;
a suspension time calculating unit that calculates a suspension time for which image formation by the image forming unit is suspended; and
a correction amount calculating unit that calculates a correction amount for an image formation condition of the image forming unit based on the suspension time calculated by the suspension time calculating unit, wherein the correction amount calculating unit calculates a correction amount using an approximate formula whose sections are represented by linear functions.

### Claim 2

An image forming apparatus comprising:
an image forming unit that forms an image by forming an electrostatic latent image on an image carrying body, developing the electrostatic latent image by sticking a developer on the image carrying body, and transferring the developer to a recording subject medium;
a suspension time calculating unit that calculates a suspension time for which image formation by the image forming unit is suspended;
a correction amount calculating unit that calculates a correction amount for an image formation condition of the image forming unit based on the suspension time calculated by the suspension time calculating unit; and
a cumulatively counting unit that counts a first characteristic value indicating the number of times of image formation by the image forming unit as a cumulative value which is irrelevant to occurrence/non-occurrence of a suspension of image formation, wherein the correction amount calculating unit calculates a correction amount based on the suspension time and the first characteristic value calculated by the cumulatively counting unit.

### Claim 3 (depends on 2)

The image forming apparatus according to claim 2, further comprising:
a consecutively counting unit that counts a second characteristic value indicating the number of times images is formed consecutively by the image forming unit without a suspension, wherein the correction amount calculating unit includes:
a first calculating unit that corrects the second characteristic value counted by the consecutively counting unit based on the suspension time; and
a second calculating unit that calculates a correction amount based on the first characteristic value and the second characteristic value corrected by the first calculating unit.

### Claim 4 (depends on 3)

The image forming apparatus according to claim 3, wherein the first calculating unit corrects the second characteristic value by multiplying the second characteristic value by a coefficient which is a function of the suspension time, and wherein the function is defined in a plurality of ranges of the suspension time to be equal to 1 when the suspension time is equal to 0 and to be equal to 0 when the suspension time is greater than a predetermined suspension time greater than 0.

### Claim 5 (depends on 4)

The image forming apparatus according to claim 4, wherein the coefficient is defined as a linear function in the plurality of ranges of the suspension time.

### Claim 6 (depends on 5)

The image forming apparatus according to claim 5, wherein the plurality of ranges is four ranges.

### Claim 7 (depends on 2)

The image forming apparatus according to claim 2, further comprising an image forming state detecting unit that detects an image forming state of the image forming unit, wherein the correction amount calculating unit calculates a correction amount based on a correction amount for the image formation condition that corresponds to the image forming state detected by the image forming state detecting unit.

### Claim 8

An image forming apparatus comprising:
an image forming unit that forms an image by forming an electrostatic latent image on an image carrying body, developing the electrostatic latent image by sticking a developer on the image carrying body, and transferring the developer to a recording subject medium;
an image forming state detecting unit that detects an image forming state of the image forming unit;
an image formation condition calculating unit that calculates an image formation condition of the image forming unit that corresponds to the image forming state detected by the image forming state detecting unit;
a cumulatively counting unit that counts a first characteristic value indicating the number of times of image formation by the image forming unit as a cumulative value, which is irrelevant to occurrence/non-Occurrence of a suspension of image formation;
a first correction amount calculating unit that calculates a first correction amount for the image formation condition based on the first characteristic value counted by the cumulatively counting unit;
a consecutively counting unit that counts a second characteristic value indicating the number of times images is formed consecutively by the image forming unit without a suspension;
a suspension time calculating unit that calculates a suspension time for which image formation by the image forming unit has been suspended;
a second characteristic value correcting unit that corrects the second characteristic value counted by the consecutively counting, unit based on the suspension time calculated by the suspension time calculating unit; and
a second correction amount calculating unit that calculates a second correction amount for the image formation condition based on the second characteristic value corrected by the second characteristic value correcting unit.

### Claim 9 (depends on 8)

The image forming apparatus according to claim 8, wherein the image forming state detecting unit includes; a patch forming unit that causes the image forming unit to form a patch for density measurement; and a density measuring unit that measures a density of the patch formed by the patch forming unit.