Ink Set Pigment Selection for Dark Blue Color Reproduction
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Solution Overview
Problem
Existing ink sets struggle to reproduce colors with low luminance and high chromaticity in the blue region, particularly at L* values of 20 or less, while maintaining color reproduction in other regions like green, due to limitations in the CIE/L*a*b* color model and the use of C.I. pigment blue 60 reducing chromogenicity in the green region.
Innovation Solution
An ink set comprising a cyan ink composition with C.I. pigment blue 15:6, a magenta ink composition with a quinacridone pigment or quinacridone solid solution pigment, and a yellow ink composition with specific pigments, such as C.I. pigment yellow 74, to extend the color reproduction range in the blue region while maintaining excellence in the green region, using a combination of C.I. pigment violet 19 and C.I. pigment red 202 in the magenta ink composition to enhance chromogenicity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If C.I. pigment blue 60 is used in cyan ink composition to extend color reproduction range, then blue region color reproduction is improved, but green region chromogenicity deteriorates
Solution Approach 1:
The patent changes the pigment parameter from C.I. pigment blue 60 to C.I. pigment blue 15:6, which has different spectral characteristics. This parameter change allows extension of the blue region color reproduction range (L*≤20, a*≥30, b*≤-75) while avoiding the harmful effect on green region chromogenicity that occurs with pigment blue 60
Solution Approach 2:
The patent uses a composite ink set formulation combining cyan ink with C.I. pigment blue 15:6, magenta ink with quinacridone pigments, and yellow ink with specific pigments. This composite approach achieves wide color reproduction in the blue region while maintaining excellent chromogenicity in the green region, as the pigment combinations are selected to complement each other's spectral properties
2Adaptability or versatility
If luminance is reduced to L* value of 20 or less to achieve dark blue region, then chromaticity and saturation are improved, but color reproduction capability deteriorates
Solution Approach 1:
The patent achieves dark blue region color reproduction (L*≤20, a*≥30, b*≤-75) by changing the pigment parameter to C.I. pigment blue 15:6, which maintains high chromaticity and saturation even at low luminance levels where conventional pigments would fail to reproduce color accurately
Data Source
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AI summary
An ink set includes a cyan ink composition containing C.I. pigment blue 15:6 as a pigment; a magenta ink composition containing a quinacridone pigment selected from the group consisting of C.I. pigment violet 19, C.I. pigment red 122, C.I. pigment red 202, and C.I. pigment red 209, or a quinacridone solid solution pigment formed of at least two selected from the above group; and a yellow ink composition containing a pigment selected from the group consisting of C.I. pigment yellow 74, C.I. pigment yellow 213, and C.I. pigment yellow 185.