# US 7,609,909 B2 · Image density test chart and method for determining image density level

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- Number: US 7,609,909 B2
- Document ID: US7609909B2
- Status: Granted
- Kind: B2
- Application number: 10/704,680
- Filed: 2003-11-12
- Published: 2004-07-22
- Granted: 2009-10-27
- Earliest claimed: 2002-11-12
- Assignees: Canon Kabushiki Kaisha
- Inventors: Nobuatsu Sasanuma; Makoto Yoshihara
- Web page: https://patentgrep.com/patent/US7609909B2

## CPC

- B41F 33/0036: {Devices for scanning or checking the printed matter for quality control}
- H04N 1/4078: {using gradational references, e.g. grey-scale test pattern analysis}
- B41F: PRINTING MACHINES OR PRESSES (manifolding devices or office printing machines B41L)
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

An image density discrimination chart is used to discriminate a density of a test image printed by an image forming apparatus. The chart includes an exposing portion for exposing the test image when the chart is overlaid relative to a printed recording material, a first comparison image having an upper limit level of a latitude, permitted by the image forming apparatus, for image density of the test image, and a second comparison image having a lower limit level of a latitude, permitted by the image forming apparatus, for image density of the test image.

## Claims

### Claim 1

An image density checking chart for checking whether a density of a test image on a sheet outputted by a full-color image forming apparatus is within a predetermined density range or not by an operator, said chart comprising:
an exposing portion configured to expose the test image when the chart is overlaid on the sheet;
a target density image configured to be compared to the test image to determine whether the density of the test image is a target density level or not;
an upper limit density image configured to be compared to the test image to determine whether the density of the test image is not higher than an upper limit density level of the predetermined density range or not; and
a lower limit density image configured to be compared to the test image to determine whether the density of the test image is not lower than a lower limit density level of the predetermined density range or not,
wherein only said target density image, said upper limit density image and said lower limit density image are disposed around a periphery of said exposing portion,
wherein said exposing portion is a general rectangular configuration, and wherein only said target density image, said upper limit density image, and said lower limit density image are disposed at three sides of said exposing portion,
wherein said target density image, said upper limit density image, and said lower limit density image have substantially the same size with said exposing portion, and
wherein each of said target density image, said upper limit density image and said lower limit density image have one density level.