Printhead Flex PCB Bending and Trace Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Pagewidth inkjet printheads face challenges with trace cracking in flexible printed circuit boards due to bending, and high current loads from firing multiple nozzles cause voltage dips, leading to operational issues.
Innovation Solution
Incorporating fluidic dampers with gas compression in ink conduits to manage pressure pulses and using a support structure with weir formations to preferentially prime upstream sections, along with a compact design that includes capacitors and a flexible printed circuit board anchored to reduce trace cracking and electromagnetic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the flex PCB is bent to connect contacts to the printhead IC, then the contacts can be positioned on a different side of the cartridge, but the traces in the flex PCB crack and break the connection
Solution Approach 1:
The trace is bifurcated into two separate branches before the bend and reunited after the bend. This segmentation ensures that if one branch cracks, the other maintains the electrical connection, thereby resolving the reliability issue while preserving the contact positioning flexibility.
Solution Approach 2:
The bifurcated trace design provides a backup path before the bend occurs. By preparing redundant trace paths in advance, the system cushions against the harmful effect of trace cracking, ensuring continuous electrical connection despite the necessary bending of the flex PCB.
2Reliability
If the trace is bifurcated to prevent cracking, then connection reliability improves, but electro-magnetic interference creates noise in the circuitry
Solution Approach 1:
The trace width is increased in the bifurcated sections to reduce electrical resistance and electromagnetic interference. By changing the geometric parameters of the traces, the system maintains reliable connection while minimizing the harmful electromagnetic noise generated by the bifurcated path.
3Productivity
If multiple nozzles are fired simultaneously to increase print speed, then productivity improves, but high current loads cause voltage dips
Solution Approach 1:
Capacitors are pre-charged during idle periods and then discharged during nozzle firing sequences to provide the necessary current bursts. This preliminary action ensures that high current demands are met without causing voltage dips, allowing simultaneous firing of multiple nozzles to maintain high print speed while preserving voltage stability.
Solution Approach 2:
The capacitors are charged and discharged in periodic cycles corresponding to the print operation patterns. During non-printing idle time, capacitors charge up; during printing, they discharge to supply current bursts. This periodic action allows the system to handle high current loads from multiple nozzles firing simultaneously while maintaining voltage stability.
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
The solution effectively dampens pressure pulses, prevents nozzle flooding, and ensures consistent priming of the printhead nozzles, enhancing the reliability and efficiency of pagewidth printheads by minimizing trace cracking and voltage dips.
Implementation Method 1
a fluidic damper containing gas for compression by pressure pulses in the ink within the ink conduits to dissipate the pressure pulse
Implementation Method 2
a flexible printed circuit board anchored to the support structure between the contacts and the printhead IC
Data Source
AI summary
A printhead is provided for an inkjet printer that has a print engine controller for receiving print data and sending it to the printhead. The printhead has a printhead IC for ejecting ink and a support structure for mounting the printhead IC in the printer adjacent a paper path. The printhead IC is mounted on a face of the support structure that, in use, faces the paper path. A flexible printed circuit board (flex PCB) that has contacts for receiving print data mounted to the support structure on a face that does not face the paper path. The bent section reduces the likelihood of trace cracking by holding the flex PCB at a set radius rather than allowing the flex to follow an irregular curve and thereby risking localized points of high stress on the traces.