US7684736B2
Expired / Lapsed
US
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Image forming method, screen set and image forming apparatus
Assignee: Fujifilm Corp
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Filing: 2006-01-25
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Granted: 2010-03-23
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Expires: 2026-01-25
Abstract
Abstract An image forming apparatus for forming a color image of CMK color plates by electrophotography system in which a K color plate having highest visibility among CMYK colors is composed of a rational number mesh. Profile of halftone dots ( 201 Kh) becomes constant substantially and the factor for generating streak and unevenness is suppressed. Furthermore, C color plate and M color plate are formed of super cells and the K color plate, C color plate and M color plate are formed at an interval of 30°. Consequently, a Rosetta formed of halftone dots ( 201 Ch, 201 Mh, 201 Kh) of CMK is optimized and the factor for generating moiré component is suppressed.
Inventors
- 👤 Makoto Sugizaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:21
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/405; H04N1/4055; H04N1/4058; G; G03; G03G; G03G13/00; G03G13/01; G03G15/00; G03G15/01; G03G15/0105; G03G15/0121; G03G15/0142; G03G15/0147; G03G15/0152; G03G15/0173; G03G2215/00; G03G2215/01; G03G2215/0167; G03G2215/0174; G03G2215/0177
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
96 words
An image forming method for forming a color image with at least C, M, K plates according to an electrophotographic process, comprising the steps of: forming a K plate as a rational screen, wherein assuming a screen angle θ is expressed as θ=arctan(m/n) where m and n are natural numbers, then a size of a threshold matrix satisfies a positive integral multiple of m 2 +n 2 ; forming C and M plates as supercells; and spacing respective screen angles of the K plate, the C plate, and the M plate at respective intervals of 30°.
Claim 2
Dependent Claim
96 words
An image forming method for forming a color image with at least C, M, K plates according to an electrophotographic process, comprising the steps of: forming a K plate as a rational screen, wherein assuming a screen angle θ is expressed as θ=arctan(m/n) where m and n are natural numbers, then a size of a threshold matrix satisfies a positive integral multiple of m 2 +n 2 ; forming C and M plates as supercells; and spacing respective screen angles of the K plate, the C plate, and the M plate at respective intervals of 30°.
Claim 3
Dependent Claim
25 words
An image forming method according to claim 1 , wherein said screen angle of said K plate comprises an angle other than 0° or 45°.
Claim 4
Dependent Claim
33 words
An image forming method according to claim 1 , wherein a value produced by dividing an output resolution by a ruling for each of said C, M, K plates is smaller than 12.
Claim 5
Dependent Claim
29 words
An image forming method according to claim 1 , wherein said size of the threshold matrix of said K plate is within a range of from 80×80 to 256×256.
Claim 6
Dependent Claim
49 words
An image forming method according to claim 1 , wherein a Y plate is added to form color images using the C, M, Y, K plates, said Y plate being formed as the same rational screen as said K plate, while being shifted in phase from said K plate.
Claim 7
Dependent Claim
29 words
An image forming method according to claim 5 , wherein said Y plate is shifted in phase from said K plate within a range of from 150° to 210°.
Claim 8
Dependent Claim
24 words
An image forming method according to claim 1 , wherein variations of rulings for the respective colors are set to 10 LPI or less.
Claim 9
Dependent Claim
32 words
An image forming method according to claim 1 , wherein said respective screen angles of said K plate, said C plate and said M plate are spaced at respective intervals of 30°±1.5°.
Claim 10
Dependent Claim
96 words
A screen set for use in forming a color image with at least C, M, K plates according to an electrophotographic process, comprising: a K plate formed as a rational screen, wherein assuming a screen angle θ is expressed as θ=arctan(m/n) where m and n are natural numbers, then the size of a threshold matrix satisfies a positive integral multiple of m 2 +n 2 ; and C and M plates formed as supercells, wherein respective screen angles of said K plate, said C plate and said M plate are spaced at respective intervals of 30°.
Claim 11
Dependent Claim
96 words
A screen set for use in forming a color image with at least C, M, K plates according to an electrophotographic process, comprising: a K plate formed as a rational screen, wherein assuming a screen angle θ is expressed as θ=arctan(m/n) where m and n are natural numbers, then the size of a threshold matrix satisfies a positive integral multiple of m 2 +n 2 ; and C and M plates formed as supercells, wherein respective screen angles of said K plate, said C plate and said M plate are spaced at respective intervals of 30°.
Claim 12
Dependent Claim
95 words
An image forming apparatus for forming a color image with at least C, M, K plates according to an electrophotographic process, comprising: a K plate formed as a rational screen, wherein assuming a screen angle θ is expressed as θ=arctan(m/n) where m and n are natural numbers, then the size of a threshold matrix satisfies a positive integral multiple of m 2 +n 2 ; and C and M plates formed as supercells, wherein respective screen angles of said K plate, said C plate and said M plate are spaced at respective intervals of 30°.
Claim 13
Dependent Claim
95 words
An image forming apparatus for forming a color image with at least C, M, K plates according to an electrophotographic process, comprising: a K plate formed as a rational screen, wherein assuming a screen angle θ is expressed as θ=arctan(m/n) where m and n are natural numbers, then the size of a threshold matrix satisfies a positive integral multiple of m 2 +n 2 ; and C and M plates formed as supercells, wherein respective screen angles of said K plate, said C plate and said M plate are spaced at respective intervals of 30°.
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