Bubble-jet type ink-jet printhead with double heater

A bubble-jet type ink jet printhead, comprising:

• a substrate;
• a nozzle plate having a plurality of nozzle holes, each having a perimeter, the nozzle plate being separated a predetermined distance from the substrate by a plurality of walls disposed on a perimeter of a common ink chamber;
• a pair of first resistors disposed on said substrate underneath each perimeter of each of said plurality of nozzle holes from a first point underneath said perimeter of said nozzle hole to a second point underneath said perimeter of said nozzle hole diametrically opposite to said first point, said pair of first resistors forming a closed polygon;
• a second resistor disposed on said substrate between said first point and said second point and disposed within said closed polygon underneath said nozzle hole, said second resistor having a resistance greater than either one of said pair of first resistors;
• a common electrode line extending to each second point underneath each perimeter of each nozzle hole;
• and
• a plurality of electrical signal lines extending to respective ones of said plurality of first points underneath respective ones of said perimeters of each of said plurality of nozzle holes.

A bubble-jet type ink-jet printhead, comprising:

• a substrate;
• a nozzle plate separated at a predetermined distance from said substrate, said nozzle plate being perforated by a first plurality of nozzle holes, each nozzle hole having a central axis extending vertically from said substrate through a center of each nozzle hole, each nozzle hole having a perimeter;
• a plurality of walls disposed on a perimeter of a common chamber on said printhead, said plurality of walls attaching said nozzle plate to said substrate, said plurality of walls, said nozzle plate, and said substrate defining said common ink chamber within;
• a plurality of first resistors disposed on said substrate, said plurality of first resistors being located beneath each perimeter of each one of said first plurality of nozzle holes, pair of first resistors forming a closed pattern, said pair of first resistors being disposed under each one of said first plurality of nozzle holes;
• a plurality of second resistors being located underneath corresponding respective ones of said first plurality of nozzle holes, each one of said plurality of second resistors being surrounded by corresponding pairs of said plurality of first resistors, each one of said plurality of second resistors forming electrical contact at diametrically opposite portions of said closed pattern of corresponding pairs of said plurality of first resistors;
• a common electrical lead electrically connected to one of two points where said pair of first resistors electrically contact said second resistor;
• and
• a first plurality of signal electrical leads extending to another of said two points where said pair of first resistors make electrical contact with said second resistor.