Secondary Ink Reservoir Control for Stable Printhead Meniscus Pressure
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current ink delivery systems in single-pass printing applications face challenges in maintaining stability, particularly under high discharge conditions, where the volume of ink jetted through printheads is comparable to the volume recirculated, leading to stringent hydraulic and actuator dynamics and potential issues like uncontrolled drop formation or ink starvation.
Innovation Solution
A high stability ink delivery system with a secondary reservoir upstream of the printhead, controllably opened to atmosphere via a valve, and a secondary meniscus pump, dynamically adjusting meniscus pressure and recirculation flow rate using a pressure sensor and controller to prevent pressure fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a closed pressurized reservoir is used to control meniscus pressure, then pressure control is achieved, but system flexibility is lost and frequent reservoir replacement is required
Solution Approach 1:
The system transitions from a static closed pressurized reservoir to a dynamic open reservoir configuration where the meniscus pressure can be adjusted by changing the vertical position of the reservoir relative to the printhead, enabling flexible pressure control without frequent reservoir replacement
Solution Approach 2:
The invention changes the control parameter from fixed internal reservoir pressure to variable hydrostatic pressure determined by reservoir height, allowing continuous adjustment of meniscus pressure by simply repositioning the reservoir vertically
2Device complexity
If ink recirculation is implemented with two tanks open to atmosphere, then system simplicity is maintained, but meniscus pressure and flow rate cannot be independently adjusted
Solution Approach 1:
The system is segmented into two independent control functions: one reservoir controls meniscus pressure through vertical positioning, while a separate pump controls recirculation flow rate, allowing independent adjustment of both parameters without increasing overall system complexity
Solution Approach 2:
The open reservoir serves multiple functions: it provides hydrostatic pressure control for meniscus pressure regulation, maintains ink supply, and enables simple recirculation when combined with the pump, replacing the need for complex closed pressurized systems
3Productivity
If high discharge rates are used in single-pass printing, then productivity increases, but meniscus pressure stability deteriorates leading to uncontrolled drop formation or ink starvation
Solution Approach 1:
The system uses a pressure sensor to monitor meniscus pressure and provides feedback to a controller that adjusts the recirculation pump operation, maintaining stable meniscus pressure even at high discharge rates and preventing drop formation defects
Solution Approach 2:
The recirculation system proactively maintains ink flow and pressure balance before disruptions occur, preventing ink starvation and uncontrolled drop formation by ensuring continuous stable meniscus pressure during high-speed single-pass 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
The system enhances stability by reducing meniscus pressure perturbations by a factor of 4 to 5, allowing higher discharge rates without additional actuators, preventing ink starvation or overfilling, and maintaining system simplicity and cost-effectiveness.
Implementation Method 1
Alternatives or variations to such basic systems include configurations in which the meniscus pressure can be changed, based on hydrostatic pressure, through the use of multiple interconnected reservoirs
Implementation Method 2
a pump is configured to set the air pressure within the ink reservoir and, consequently, the meniscus pressure
Implementation Method 3
In other configurations, a siphon is connected to the supply manifold, in which the atmosphere is employed, to prevent ink exhaust
Data Source
AI summary
Disclosed are high stability ink delivery system systems and methods for their use, in which a secondary reservoir is placed upstream of a printhead. The secondary reservoir can be opened to the atmosphere through a valve, such as based on the reading of a pressure sensor placed at a point before the printhead. The purpose of this valve is to open the secondary reservoir to the atmosphere when the pressure sensor indicates that the secondary reservoir can be open while avoiding air aspiration, and closing it when this condition is not satisfied.