Single-Side Thermal Sensor Printhead Design
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Solution Overview
Problem
The challenge in inkjet printhead design is to maintain mechanical strength and seal integrity while minimizing the width of the printhead die, which is constrained by the need for thermal sensing and control circuitry, often requiring multiple thermal sensors that increase rib width disparities and hinder efficient temperature monitoring across the printhead nozzles.
Innovation Solution
A fluid ejection apparatus with a single-side thermal sensor configuration, where the thermal sensor is placed on one rib and monitors the temperature of the opposite rib, allowing for effective temperature determination and operation control without the need for sensors on both ribs, thereby reducing rib width disparities and maintaining mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If thermal sensors are placed on both ribs to monitor temperature across the printhead, then temperature monitoring precision is improved, but the rib width disparity increases and mechanical strength deteriorates
Solution Approach 1:
The patent uses thermal conduction through the substrate as an intermediary mechanism to transfer temperature information from the first rib to the thermal sensor on the second rib. This allows indirect temperature measurement without requiring physical contact between the sensor and the first rib, resolving the contradiction by maintaining measurement capability while preserving structural integrity
Solution Approach 2:
The thermal sensor on the second rib effectively creates a thermal copy or representation of the temperature condition on the first rib through substrate conduction. This copying mechanism allows temperature monitoring of the first rib without physically placing a sensor on it, thus avoiding the need to widen either rib while maintaining monitoring precision
2Measurement precision
If multiple thermal sensors are used to monitor temperature across printhead nozzles, then temperature monitoring precision is improved, but the device complexity increases
Solution Approach 1:
The single thermal sensor on the second rib serves multiple functions: it monitors temperature of the first rib, monitors temperature of the substrate, and enables control of drop ejection circuitry on both ribs. This multi-functionality eliminates the need for multiple dedicated sensors, reducing device complexity while maintaining comprehensive temperature monitoring capability
Solution Approach 2:
The substrate itself serves as a thermal conduction pathway, automatically transferring temperature information from the first rib to the sensor on the second rib without requiring additional active components or complex sensor networks. This self-service mechanism simplifies the overall system architecture
3Productivity
If the printhead die width is minimized, then manufacturing efficiency is improved, but the space for thermal sensing and control circuitry is reduced
Solution Approach 1:
The patent resolves the space constraint by moving the thermal sensor to the second rib and utilizing the substrate as a thermal conduction pathway to the first rib. This dimensional rearrangement allows temperature monitoring functionality to be achieved within the existing width constraints without requiring additional horizontal space, thereby maintaining manufacturing efficiency while preserving sensing capability
Solution Approach 2:
The patent merges the thermal sensing function with the existing rib and substrate structure. The second rib, which already exists as part of the mechanical structure, is utilized to host the thermal sensor, eliminating the need for dedicated sensor mounting space and allowing the printhead die to maintain minimal width while still accommodating thermal sensing and control circuitry
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 configuration enables efficient temperature monitoring and control of the printhead, reducing the overall width of the printhead die and enhancing mechanical strength, while maintaining seal integrity and preventing ink or air leakage during operation.
Implementation Method 1
a thermal sensor on the second rib...monitors a temperature of the second rib
Data Source
AI summary
An example provides a fluid ejection apparatus including a fluid feed slot to supply a fluid to a plurality of drop ejectors, a first rib at a first side of the fluid feed slot and supporting drop ejection circuitry to control ejection of drops of the fluid from the plurality of drop ejectors, and a second rib at a second side, opposite the first side, of the fluid feed slot supporting a thermal sensor to facilitate determination of a temperature of the first rib and the second rib.