Inkjet Printhead Ink Flow Rate Measurement via Temperature Slope
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Solution Overview
Problem
Inkjet printers face challenges in determining when the pressure regulation system fails, leading to ink starvation, clogging, and degraded print quality, with no practical method to assess the printhead's functional state, resulting in unnecessary cartridge replacements and inefficient ink usage.
Innovation Solution
The technique involves setting the printhead temperature to a steady state jetting temperature and measuring temperature changes during printing to determine ink flow rate, distinguishing between clogging, depriming, and low ink conditions, allowing for adaptive print settings and maintenance actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the printhead temperature is set to a high initial temperature to detect out of ink condition, then the detection accuracy is improved, but the printhead may suffer permanent damage
Solution Approach 1:
The patent applies parameter changes by using a predefined steady state jetting temperature (SSJT) that is safely within operating parameters, rather than using excessively high initial temperatures. The temperature is set to SSJT before measurement, which is a controlled parameter change that allows accurate detection without causing damage to the printhead.
Solution Approach 2:
The patent implements feedback by measuring the actual temperature of the printhead substrate during jetting operations and comparing it against expected temperature profiles. This feedback mechanism allows the system to detect ink flow conditions without requiring extreme temperature settings, as the temperature measurement itself provides the diagnostic information.
2Productivity
If the printhead temperature is allowed to reach high levels during printing, then the ink jetting performance is improved, but the temperature measurement for flow rate detection becomes less accurate
Solution Approach 1:
The patent applies preliminary action by establishing the printhead at a predefined steady state jetting temperature (SSJT) before performing the flow rate measurement. This preliminary temperature setting creates a known initial condition that allows for accurate temperature change measurement during the subsequent jetting operation, separating the performance optimization from the measurement process.
Solution Approach 2:
The patent uses periodic action by conducting temperature measurements during specific intervals of the printing cycle, rather than continuously monitoring throughout high-temperature operation. The temperature is measured during jetting operations at controlled intervals, allowing the system to capture temperature change data that reflects ink flow conditions while the printhead is operating at high temperature.
3Loss of substance
If the ink flow rate is reduced to extend cartridge life, then the ink usage efficiency is improved, but the print quality may be degraded
Solution Approach 1:
The patent applies dynamics by enabling the system to adaptively adjust print settings based on real-time ink flow rate measurements. The printhead can dynamically change its operating parameters such as jetting frequency, pulse width, or temperature settings to match the available ink flow rate, allowing the system to optimize both ink usage efficiency and print quality simultaneously rather than operating at fixed settings.
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 method accurately assesses the printhead's functional state, enabling users to extend ink cartridge life, prevent unnecessary replacements, and maintain print quality by adjusting print settings based on available ink flow, thus optimizing ink usage and reducing waste.
Implementation Method 1
measuring temperature changes during printing to determine ink flow rate
Implementation Method 2
The ink that flows through the nozzles functions acts as a coolant and removes heat from the printhead substrate
Data Source
AI summary
A method of determining the state of a printhead/cartridge in a thermal inkjet printer. An inkjet printhead undergoes a jetting operation in which a jetting frequency is selected and a corresponding steady state printhead temperature is known. The printhead is heated to the steady state temperature. Then the printhead is jetted with all nozzles for a predetermined period of time. Temperature samples from the printhead are obtained and the change in the printhead temperature for a short period of time is used to determine a slope in the temperature change. From the slope of printhead temperature changes, the ink flow rate through the printhead can be determined. The flow rate of ink through the printhead can be used to determine the various states of the printhead, including out of ink, clogged, deprimed, a taped printhead, etc.