Double Data Rate Firing Cell Circuit for Inkjet Printhead Pin Reduction
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Solution Overview
Problem
As the number of drop generators in inkjet printheads increases to improve printing speed and quality, the number of input pads required to energize the firing resistors becomes impractical, leading to higher costs and complexity.
Innovation Solution
The implementation of a double data rate firing cell circuit with on-board address generation and a two-cycle data capture method reduces the number of input pads by allowing nearly twice the number of firing resistors to be energized without increasing the firing frequency or input pads, achieved through combined FIRE lines, precharge, select, and data lines, and on-board address generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of drop generators per printhead is increased to improve printing speed and quality, then printing performance is improved, but the number of input pads required increases leading to higher cost and complexity
Solution Approach 1:
The patent combines multiple FIRE lines into a single shared FIRE line that serves multiple drop generator groups. This merging allows the same physical line to be reused across different groups by coordinating activation sequences, thereby reducing the total number of input pads required while maintaining the ability to control a large number of drop generators for high printing speed and quality
Solution Approach 2:
The patent implements a two-cycle data capture method where data is latched and prepared in advance during a first cycle, and then fired during a second cycle. This preliminary action allows data to be captured and stored before the actual firing occurs, enabling the system to manage more drop generators than there are physical input pads by using temporal separation of data capture and firing operations
2Manufacturing precision
If the number of drop generators per printhead is increased to improve printing quality, then image resolution is improved, but the number of input pads required increases leading to higher manufacturing cost
Solution Approach 1:
The patent merges multiple FIRE lines into a shared infrastructure where a single physical FIRE line serves multiple drop generator groups. This consolidation reduces the number of input pads required, lowering manufacturing complexity and cost while still supporting a high number of drop generators necessary for achieving high image resolution through increased printing capacity
3Ease of manufacture
If the number of input pads is reduced to lower cost and complexity, then manufacturing efficiency is improved, but the number of firing resistors that can be energized is limited
Solution Approach 1:
The patent uses a two-cycle data capture method where data is latched during a first cycle and then fired during a second cycle. This preliminary data capture and storage mechanism allows the system to manage and energize a large number of firing resistors (nearly twice the number of input pads) by utilizing temporal separation between data capture and firing operations, thereby overcoming the limitation of having fewer input pads
Solution Approach 2:
The patent implements periodic operation through two distinct cycles: a data capture cycle and a firing cycle. By alternating between these cycles, the system can service more firing resistors than there are input pads, as each input pad is reused across different cycles. This periodic action enables manufacturing efficiency with fewer input pads while maintaining the ability to energize a large quantity of firing resistors for high-quality printing
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 approach enables a lower pin-count interface, allowing for a smaller printhead width while maintaining high printing quality and speed, reducing production costs and complexity.
Implementation Method 1
The ink is heated with small electric heaters, such as thin film resistors referred to herein as firing resistors. Heating the ink causes the ink to vaporize and be ejected through the nozzles.
Implementation Method 2
Heating the ink causes the ink to vaporize and be ejected through the nozzles.
Data Source
AI summary
A fluid ejection device includes groups of firing cells, sharing a common fire signal and a common address selection mechanism, each firing cell having a drop generator for ejecting fluid and a dynamic memory addressable by the common address selection mechanism. Circuitry interfaces with the firing cells to allow the capture of data during two consecutive select cycles, then firing of all cells during a third cycle.