Temperature control circuit for an inkjet printhead
View Patent ↗A temperature control circuit for an inkjet printhead including a temperature sensor portion that generates an output current made up of the sum of a current proportional to a sensed temperature on the inkjet printhead and an offset current, and an offset current correction portion that generates a correction current that is subtracted from the output current to at least partially compensate for the offset current, the output current as compensated by the correction current being output as a temperature control circuit output current.
1. A temperature control circuit for an inkjet printhead comprising:
a temperature sensor portion that generates an output current comprising the sum of a current proportional to a sensed temperature on the inkjet printhead and an offset current; and
an offset current correction portion that generates a correction current that is subtracted from the output current to at least partially compensate for the offset current, the output current as compensated by the correction current being output as a temperature control circuit output current.
2. The temperature control circuit of claim 1 , wherein the offset current correction portion comprises a floating gate transistor.
3. The temperature control circuit of claim 2 , wherein the offset current correction portion comprises a current mirror that reduces the correction current.
4. The temperature control circuit of claim 2 , wherein the temperature control circuit has a program mode in which the floating gate is charged.
5. The temperature control circuit of claim 2 , wherein the temperature control circuit has a read mode in which a charge on the floating gate is read to generate the correction current.
6. The temperature control circuit of claim 1 , wherein the temperature sensor portion comprises a band-gap temperature detection circuit.
7. An inkjet printhead comprising:
one or more temperature control circuits each comprising:
a temperature sensor portion that generates an output current comprising the sum of a current proportional to a sensed temperature on the inkjet printhead and an offset current; and
an offset current correction portion that generates a correction current that is subtracted from the output current to at least partially compensate for the offset current, the output current as compensated by the correction current being output as a temperature control circuit output current.
8. The inkjet printhead of claim 7 , wherein the offset current correction portion comprises a floating gate transistor.
9. The inkjet printhead of claim 8 , wherein the offset current correction portion comprises a current mirror that reduces the correction current.
10. The inkjet printhead of claim 8 , wherein the temperature control circuit has a program mode in which the floating gate is charged.
11. The inkjet printhead of claim 8 , wherein the temperature control circuit has a read mode in which a charge on the floating gate is read to generate the correction current.
12. The inkjet printhead of claim 7 , wherein the temperature sensor portion comprises a band-gap temperature detection circuit.
13. The inkjet printhead of claim 7 , further comprising one or more heaters, wherein the one or more heaters are controlled based on the temperature control circuit output current.