Printhead IC Temperature Sensor Array for Uniform Drop Ejection
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Solution Overview
Problem
Inkjet printers with pagewidth printheads face challenges in maintaining uniform drop ejection characteristics due to temperature variations along the printhead, leading to visible artifacts in printed pages, as ink viscosity is temperature-dependent and affects nozzle performance.
Innovation Solution
Incorporating an array of nozzles with temperature sensors and drive circuitry that adjusts electrical pulses based on temperature readings to compensate for viscosity differences across the printhead, ensuring uniform drop ejection by defining temperature zones with specific pulse profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pagewidth printhead with a large array of nozzles is used to increase print speed, then productivity is improved, but temperature variations along the printhead cause non-uniform ink viscosity and drop ejection characteristics
Solution Approach 1:
The printhead array is divided into multiple temperature zones, with each zone monitored by dedicated temperature sensors and controlled by zone-specific drive waveforms. This segmentation allows independent optimization of each zone to compensate for temperature variations while maintaining overall high-speed printing capability.
Solution Approach 2:
Different drive waveforms are applied to different temperature zones along the printhead array. Each zone receives customized pulse widths and voltages tailored to its local temperature conditions, ensuring uniform drop ejection characteristics across the entire pagewidth array despite temperature gradients.
2Manufacturing precision
If temperature sensors and zone-based control are added to compensate for viscosity variations, then uniformity of drop ejection is improved, but device complexity increases
Solution Approach 1:
Instead of providing individual control for every nozzle, the system uses a moderate number of temperature zones (e.g., 3-7 zones) that partially cover the array. This partial action approach achieves sufficient uniformity correction without the excessive complexity of full individual nozzle control.
Solution Approach 2:
The system changes physical parameters (temperature, viscosity) by modifying drive waveform characteristics (pulse width, voltage) in response to temperature sensor feedback. This parameter-based control achieves uniformity correction through software/firmware adjustments rather than complex hardware modifications.
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
This solution enhances print quality by maintaining uniform drop ejection characteristics across the entire printhead, improving the consistency and quality of printed pages.
Implementation Method 1
a plurality of temperature sensors for sensing the temperature of the printhead IC within each of the regions respectively
Data Source
AI summary
A printhead IC comprising: an array of nozzles having a plurality of adjacent regions; and, drive circuitry for sending an electrical pulse to each of the nozzles individually such that they eject a drop of printing fluid; and, a plurality of temperature sensors for sensing the temperature of the printhead IC within each of the regions respectively.