Method and apparatus for preventing color bleed in a multi-ink printing system

A method for printing multi-color images on a substrate in which color bleed between adjacent colored regions is prevented comprising the steps of:

• providing an ink cartridge comprising:
• a housing having at least a first compartment and a second compartment therein, said first compartment being maintained separately from said second compartment;
• and
• a printhead in fluid communication with each of said first compartment and said second compartment, said printhead comprising a plurality of resistors and an outer plate having a plurality of openings therethrough, said first compartment comprising a supply therein of a first ink composition comprising about 2-7% by weight of a first coloring agent, with said second compartment comprising a supply therein of a second ink composition comprising about 2-7% by weight of a second coloring agent and about 1-15% by weight of a precipitating agent, said precipitating agent comprising at least one multi-valent metal salt which will react with said first coloring agent in said first ink composition in order to form a precipitate therefrom, said multi-valent metal salt comprising a multi-valent metal cation selected from the group consisting of Ca.sup.+2, Cu.sup.+2, Co.sup.+2, Ni.sup.+2, Fe.sup.+2, La.sup.+3, Nd.sup.+3, Y.sup.+3, and Al.sup.+3 ;
• activating said ink cartridge in order to apply said first ink composition from said first compartment onto said substrate in a first region thereon;
• activating said ink cartridge in order to apply said second ink composition from said second compartment onto said substrate in a second region thereon, said second region being directly adjacent to said first region so that said second region contacts said first region;
• and
• reacting said precipitating agent in said second ink composition with said first coloring agent in said first ink composition at a position on said substrate where said first region contacts said second region so that said precipitate is formed at said position in order to prevent color bleed between said first ink composition in said first region and said second ink composition in said second region.

A method for printing multi-color images on a substrate in which color bleed between adjacent colored regions is prevented comprising the steps of:

• providing a first ink cartridge comprising a housing having at least one compartment therein, said first ink cartridge further comprising a printhead in fluid communication with said compartment, said printhead of said first ink cartridge comprising a plurality of resistors and an outer plate having at least one opening therethrough, said compartment of said first ink cartridge comprising a supply therein of a first ink composition comprising about 2-7% by weight of a first coloring agent;
• providing a second ink cartridge comprising a housing having at least one compartment therein, said second ink cartridge further comprising a printhead in fluid communication with said compartment of said second ink cartridge, said printhead of said second ink cartridge comprising a plurality of resistors and an outer plate having at least one opening therethrough, said compartment of said second ink cartridge comprising a supply therein of a second ink composition comprising about 2-7% by weight of a second coloring agent and about 1-15% by weight of a precipitating agent, said precipitating agent comprising at least one multi-valent metal salt which will react with said first coloring agent in said first ink composition in order to form a precipitate therefrom, said multi-valent metal salt comprising a multi-valent metal cation selected from the group consisting of Ca.sup.+2, Cu.sup.+2, Co.sup.+2, Ni.sup.+2, Fe.sup.+2, La.sup.+3, Nd.sup.+3, Y.sup.+3, and Al.sup.+3 ;
• activating said first ink cartridge in order to apply said first ink composition therefrom onto said substrate in a first region thereon;
• activating said second ink cartridge in order to apply said second ink composition therefrom onto said substrate in a second region thereon, said second region being directly adjacent to said first region so that said second region contacts said first region;
• and
• reacting said precipitating agent in said second ink composition with said first coloring agent in said first ink composition at a position on said substrate where said first region contacts said second region so that said precipitate is formed at said position in order to prevent color bleed between said first ink composition in said first region and said second ink composition in said second region.