Page image and fault tolerance control apparatus for printing systems

A printing system comprising:

• print heads containing main actuators and redundant actuators, wherein said print heads further comprise:
• (a) a plurality of drop-emitter nozzles,
• (b) a body of ink associated with said nozzles,
• (c) drop selection apparatus adapted to select predetermined nozzles and to generate a difference in meniscus position between ink in selected and non-selected nozzles, and
• (d) drop separation apparatus adapted to cause ink from selected nozzles to separate as drops from the body of ink, while allowing ink to be retained in non-selected nozzles, said drop selecting means being capable of producing said difference in meniscus position in the absence of said drop separation means;
• a memory which records the logical location of faulty portions of said print heads;
• an image data source adapted (1) to provide image data to said main actuators at a time which causes an output related to the provided image data to be printed at a corresponding position on a print medium and (2) to provide image data to said redundant actuators at a time which causes an output related to the image data to be printed at a corresponding position on a print medium;
• and
• a data selector adapted to select between the provision of image data to the main actuators or the redundant actuators, said data selector being controlled by the contents of said memory.

A printing system comprising:

• print heads containing main actuators and redundant actuators, wherein said print heads further comprise:
• (a) a plurality of drop-emitter nozzles,
• (b) a body of ink associated with said nozzles, said ink exhibiting a surface tension decrease of at least 10 mN/m over a 30.degree. C. temperature range,
• (c) drop selection apparatus adapted to select predetermined nozzles and to generate a difference in meniscus position between ink in selected and non-selected nozzles, and
• (d) drop separating means for causing ink from selected nozzles to separate as drops from the body of ink, while allowing ink to be retained in nonselected nozzles;
• a memory which records the logical location of faulty portions of said print heads;
• an image data source adapted (1) to provide image data to said main actuators at a time which causes an output related to the provided image data to be printed at a corresponding position on a print medium and (2) to provide image data to said redundant actuators at a time which causes an output related to the image data to be printed at a corresponding position on a print medium;
• and
• a data selector adapted to select between the provision of image data to the main actuators or the redundant actuators, said data selector being controlled by the contents of said memory.