US-12623466-B2 - Image forming apparatus

US12623466B2US 12623466 B2US12623466 B2US 12623466B2US-12623466-B2

Abstract

A first test pattern includes first bands respectively corresponding to nozzle groups of which each includes nozzles with a first interval such that the first band includes thin lines respectively corresponding to the nozzles. A second test pattern includes second bands respectively corresponding to nozzle subgroups of which each includes nozzles with a second interval in each nozzle group such that the second band includes thin blank lines respectively corresponding to the nozzle and a correction process is performed for adjacent pixels of the thin blank lines. Regarding a first band including density defect detected in a scanned image of the printed first test pattern, in a scanned image of the printed second test pattern, detected as an ink ejection malfunction nozzle is a nozzle corresponding to the thin blank line in the second band not including density defect among the second bands corresponding to the plural nozzle subgroups of the first band.

Inventors

Jun Nakano

Assignees

KYOCERA DOCUMENT SOLUTIONS INC.

Dates

Publication Date: 20260512
Application Date: 20220927
Priority Date: 20210928

Claims (3)

1 . An image forming apparatus, comprising: a recording head that ejects ink corresponding to an image to be printed, using arranged nozzles; and an ink-ejection-malfunction-nozzle detecting unit configured to detect an ink ejection malfunction nozzle among the nozzles; wherein the ink-ejection-malfunction-nozzle detecting unit (a) sets plural nozzle groups so as to be shifted sequentially by one nozzle such that each of the plural nozzle groups includes nozzles with a predetermined first interval among the arranged nozzles, (b) prints using the recording head a first test pattern that includes first bands respectively corresponding to the nozzle groups such that the first band includes thin lines respectively corresponding to the nozzles in the nozzle group, (c) sets plural nozzle subgroups from the plural nozzle groups so as to be shifted sequentially by one nozzle such that each of the plural nozzle subgroups includes nozzles with a predetermined second interval among the nozzles in each of the nozzle groups, (d) prints using the recording head a second test pattern that includes second bands respectively corresponding to the nozzle subgroups such that the second band includes thin blank lines respectively corresponding to the nozzles in the nozzle subgroup and a correction process is performed for adjacent pixels of the thin blank lines, (e) acquires a scanned image of the printed first test pattern and a scanned image of the printed second test pattern, (f) detects a first band including density defect in the scanned image of the first test pattern, and (g) detects a second band not including density defect owing to the correction process in the scanned image of the second test pattern, among the plural second bands corresponding to the plural nozzle subgroups in the nozzle group of the detected first band and detects as the ink ejection malfunction nozzle a nozzle corresponding to the thin blank line in the second band not including density defect.
2 . The image forming apparatus according to claim 1 , wherein the ink-ejection- malfunction-nozzle detecting unit smoothes the scanned image of the first test pattern, and detects the first band including density defect in the smoothed scanned image of the first test pattern.
3 . The image forming apparatus according to claim 1 , further comprising a correction processing unit that performs the correction process corresponding to the ink ejection malfunction nozzle in the image.

Description

TECHNICAL FIELD The present invention relates to an image forming apparatus. BACKGROUND ART An image forming apparatus includes a recording head in which plural nozzles are arranged, and detects an ink droplet hitting position and an ink droplet hitting area of each nozzle and thereby measures a deviation value of an ink ejection malfunction nozzle and generates a nozzle profile, and performs a correction process based on the nozzle profile (see PATENT LITERATURE #1, for example). CITATION LIST Patent Literature PATENT LITERATURE #1: Japanese Patent Application Publication No. 2004-58282. SUMMARY OF INVENTION Technical Problem However, in the aforementioned image forming apparatus, in order to measure the aforementioned deviation value, an image scanning device of a high resolution such as 4800 dpi is required and results in a high cost of the apparatus. The present invention has been conceived in view of the aforementioned problem. It is an object of the present invention to obtain an image forming apparatus that properly detects an ink ejection malfunction nozzle with a relatively low cost. Solution to Problem An image forming apparatus according to the present invention includes a recording head that ejects ink corresponding to an image to be printed, using arranged nozzles; and an ink-ejection-malfunction-nozzle detecting unit configured to detect an ink ejection malfunction nozzle among the nozzles. Further, the ink-ejection-malfunction-nozzle detecting unit (a) sets plural nozzle groups so as to be shifted sequentially by one nozzle such that each of the plural nozzle groups includes nozzles with a predetermined first interval among the arranged nozzles, (b) prints using the recording head a first test pattern that includes first bands respectively corresponding to the nozzle groups such that the first band includes thin lines respectively corresponding to the nozzles in the nozzle group, (c) sets plural nozzle subgroups so as to be shifted sequentially by one nozzle such that each of the plural nozzle subgroups includes nozzles with a predetermined second interval among the nozzles in each of the nozzle groups, (d) prints using the recording head a second test pattern that includes second bands respectively corresponding to the nozzle subgroups such that the second band includes thin blank lines respectively corresponding to the nozzles in the nozzle subgroup and a correction process is performed for adjacent pixels of the thin blank lines, (e) acquires a scanned image of the printed first test pattern and a scanned image of the printed second test pattern, (f) detects a first band including density defect in the scanned image of the first test pattern, and (g) detects a second band not including density defect owing to the correction process in the scanned image of the second test pattern, among the plural second bands corresponding to the plural nozzle subgroups in the nozzle group of the detected first band and detects as the ink ejection malfunction nozzle a nozzle corresponding to the thin blank line in the second band not including density defect. Advantageous Effect of Invention By means of the present invention, obtained is an image forming apparatus that properly detects an ink ejection malfunction nozzle with a relatively low cost. These and other objects, features and advantages of the present invention will become more apparent upon reading of the following detailed description along with the accompanied drawings. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 shows a side view that indicates an internal mechanical configuration of an image forming apparatus in an embodiment according to the present invention; FIG. 2 shows a plane view of an example of recording heads 1a to 1d in the image forming apparatus 10 shown in FIG. 1; FIG. 3 shows a block diagram that indicates an electronic configuration of the image forming apparatus 10 in the embodiment according to the present invention; FIG. 4 shows a diagram that indicates an example of a first test pattern; FIG. 5 shows a diagram that indicates an example of a second test pattern; FIG. 6 shows a diagram that explains detection of density defect in a scanned image of the first test pattern; and FIG. 7 shows a diagram that explains detection of an ink ejection malfunction nozzle based on a scanned image of the second test pattern. DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment according to aspects of the present invention will be explained with reference to a drawing. FIG. 1 shows a side view that indicates an internal mechanical configuration of an image forming apparatus in an embodiment according to the present invention. The image forming apparatus 10 in this embodiment is an apparatus such as printer, copier, facsimile machine or multi function peripheral. The image forming apparatus 10 shown in FIG. 1 includes a print engine 10a and a sheet transportation unit 10b. The print engine 10a physically forms an image to be printed on a print sh