Inkjet Printhead Temperature Control Circuit Offset Correction
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Solution Overview
Problem
Inkjet printhead temperature sensors require unique offset current values stored remotely, increasing complexity and cost due to the need for individual memory locations on each printhead IC.
Innovation Solution
A temperature control circuit with a band-gap temperature detection circuit and an offset current correction portion using a floating gate transistor to generate a correction current, allowing all sensors to have identical offset currents, reducing calculation complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each sensor has a unique stored offset value in remote memory, then temperature measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the offset current correction functionality directly into the temperature sensor portion on the printhead IC by integrating a floating gate transistor. This merging eliminates the need for separate remote memory storage and individual memory locations for each sensor, thereby reducing device complexity while maintaining temperature measurement accuracy through on-chip offset correction.
Solution Approach 2:
The floating gate transistor in the temperature sensor portion provides self-contained offset current correction by generating a correction current that compensates for offset variations. This self-service mechanism eliminates dependence on remote memory systems and external calibration processes, reducing both complexity and cost while preserving measurement precision.
2Measurement precision
If each sensor has a unique stored offset value, then temperature control accuracy is improved, but manufacturing cost increases
Solution Approach 1:
By merging the offset correction functionality into the temperature sensor portion through integration of a floating gate transistor on the printhead IC, the patent eliminates the need for separate memory components and remote storage systems. This integration simplifies the manufacturing process and reduces component costs while maintaining temperature control accuracy.
Solution Approach 2:
The floating gate transistor serves multiple functions: it generates the correction current for offset compensation and stores the calibration data locally. This multi-functionality reduces the number of separate components needed, thereby lowering manufacturing costs while maintaining the ability to achieve accurate temperature control across all sensors.
3Area of stationary object
If offset current varies from sensor to sensor, then sensor layout space is minimized, but calculation complexity increases
Solution Approach 1:
The patent performs preliminary calibration by programming the floating gate transistor during manufacturing to store the specific offset correction value for each sensor. This preliminary action eliminates the need for complex runtime calculations to determine offset values, as the correction is already embedded in the floating gate transistor and applied automatically during temperature measurement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables self-contained temperature control on the printhead IC, reducing the need for remote memory and simplifying calculations, thereby lowering printer costs and improving temperature control consistency.
Implementation Method 1
the temperature sensor portion comprises a band-gap temperature detection circuit
Implementation Method 2
the offset current correction portion comprises a floating gate transistor
Data Source
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AI summary
A temperature control circuit for an inkjet printhead including a temperature sensor portion that generates an output current(IM40) 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(IM16) that is subtracted from the output current(IM40) to at least partially compensate for the offset current, the output current(IDIFF) as compensated by the correction current being output as a temperature control circuit output current.