Ink Jet Printhead with Segmented Drop Generators
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Solution Overview
Problem
Thermal ink jet printheads with uniform drop sizes face challenges in high-speed printing, as larger drops can't resolve images well, and replacing printheads in web presses is impractical due to the large number of units involved.
Innovation Solution
Ink jet printheads are designed with alternating high drop weight (HDW) and low drop weight (LDW) drop generators, allowing for adjustable drop sizes and improved image quality by using HDW for text and graphics and LDW for images, with specific nozzle designs and control systems to manage drop placement and printing speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If larger drops are used for high-speed printing, then printing speed is improved, but image resolution deteriorates
Solution Approach 1:
The printhead is segmented into multiple types of drop generators (HDW and LDW) with different drop weights. HDW drop generators produce larger drops for text and graphics, while LDW drop generators produce smaller drops for images. This segmentation allows each type to be optimized for its specific function, resolving the contradiction between speed and resolution.
Solution Approach 2:
Different regions of the printhead are assigned different drop generator types based on local requirements. Text and graphics regions use HDW drop generators for speed, while image regions use LDW drop generators for resolution. This local differentiation enables simultaneous optimization of both printing speed and image quality in different areas.
2Ease of manufacture
If uniform drop size is used, then manufacturing simplicity is maintained, but printing versatility deteriorates
Solution Approach 1:
The printhead is divided into distinct HDW and LDW drop generator sections, with each segment optimized for specific content types. This segmentation provides manufacturing simplicity within each segment while achieving overall system versatility through the combination of different drop weight types.
Solution Approach 2:
The printhead system achieves multi-functionality by incorporating both HDW and LDW drop generators in a single device. This universal design enables the printhead to handle various content types (text, graphics, images) with appropriate drop sizes, eliminating the need for multiple specialized printheads.
3Manufacturing precision
If printheads are switched out by job, then printing quality can be optimized, but device complexity and operation difficulty increase
Solution Approach 1:
Multiple drop generator types (HDW and LDW) are merged into a single printhead assembly. This combination eliminates the need to switch between different printheads for different content types, as both drop weight types are available simultaneously in one device, simplifying operation while maintaining quality.
Solution Approach 2:
The printhead is designed as a universal device that can print text, graphics, and images with appropriate drop sizes. This multi-functional capability replaces the need for multiple specialized printheads, reducing operational complexity while maintaining optimized printing quality for different content types.
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 enables high-speed printing with improved quality for both text and images, reducing drop weight and grain in images, while maintaining high printing speeds, even at 800 feet per minute, by strategically using HDW and LDW drop generators.
Implementation Method 1
When a firing pulse is applied to the heating resistor, a steam or solvent bubble is formed within the ejection chamber
Implementation Method 2
When a firing pulse is applied to the heating resistor, a steam or solvent bubble is formed within the ejection chamber, which forces an ink drop out the nozzle
Data Source
AI summary
Printheads and printers are described herein. In one example, a printhead includes a plurality of nozzles configured to eject ink drops of different sizes wherein a low drop weight (LDW) drop is ejected through a nozzle with a circular bore (CB), and a high drop weight (HDW) drop is ejected through a nozzle with a non-circular bore (NCB).