Claims
- 1. A method for controlling a thermal inkjet printhead having a plurality of nozzles, in which for each one nozzle there is a corresponding nozzle chamber, a corresponding heating resistor, and a corresponding segmented transistor, the corresponding segmented transistor for said one nozzle being electrically coupled to the corresponding heating resistor, each one segmented transistor having a first portion and a second portion, a common source connection for the first portion and the second portion, a common drain connection for the first portion and second portion, and a first gate connection for the first portion and a second gate for the second portion, and wherein for each said one nozzle the common drain connection is electrically coupled to the heating resistor of said one nozzle, and wherein for each said segmented transistor the second portion is smaller than the first portion so as to have a maximum current magnitude rating which is less than a maximum current magnitude rating for the first portion, the method comprising the steps of:
- firing a first nozzle of said plurality of nozzles in response to a first signal being in an active state, the first signal being received at the first gate connection of the segmented transistor of said first nozzle, the active first signal causing said segmented transistor of said first nozzle to output to the heating resistor of said first nozzle an output signal at sufficient current to cause said first nozzle to fire;
- monitoring temperature of the printhead; and
- when the monitored temperature falls below a threshold temperature, warming the first nozzle in response to an active second signal, the second signal being received as the second gate connection of the segmented transistor of said first nozzle, the second signal causing the segmented transistor to output to the heating resistor the output signal at insufficient current to cause said first nozzle to fire.
- 2. The method of claim 1, wherein the plurality of nozzles and the nozzle chamber, heating resistor, drive transistor and warming transistor for each of the plurality of nozzles are formed on a common die, and wherein for each nozzle chamber, the corresponding drive transistor occupies a first area of the die, and the corresponding warming transistor occupies a second area of the die dedicated to the warming transistor.
- 3. The method of claim 1, wherein the plurality of nozzles and the nozzle chamber, heating resistor, drive transistor and warming transistor for each of the plurality of nozzles are formed on a common die, and wherein for each nozzle chamber, the corresponding drive transistor occupies a first area of the die, and the corresponding warming transistor occupies a second area of the die, wherein the second area is shared by the warming transistor and the drive transistor.
- 4. The method of claim 1,
- wherein the step of firing the first nozzle occurs in response to an active first signal received at the first gate of the segmented transistor of the first nozzle and an active second signal received at the second gate of the segmented transistor of the first nozzle, the active first signal and active second signal causing the transistor to output to the heating resistor the output signal at sufficient current to cause said first nozzle to fire.
CROSS REFERENCE TO RELATED APPLICATION(S)
This is a continuation of copending application Ser. No. 08/819,126 filed on Mar. 17, 1997.
US Referenced Citations (8)
Continuations (1)
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Number |
Date |
Country |
Parent |
819126 |
Mar 1997 |
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