Recirculating Inkjet Printhead Cleaning Method
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Solution Overview
Problem
Existing cleaning methods for clogged nozzles in printing units are either expensive due to the need for replacing malfunctioning printheads or inefficient as they may not effectively clear clogs without wasting ink.
Innovation Solution
A cleaning method that interrupts ink flow, uses a support to occlude nozzles, and introduces a substance into the recirculation line to clear clogs without removing the printhead, thus minimizing ink waste and downtime.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If printhead replacement is used to clear clogged nozzles, then nozzle functionality is restored, but cost and downtime increase
Solution Approach 1:
The invention extracts the cleaning operation from the traditional replacement process. Instead of removing and replacing the entire printhead, the method introduces a cleaning substance through the recirculation system to selectively remove clogs while keeping the printhead in place, thus restoring functionality without downtime associated with replacement.
Solution Approach 2:
The invention recovers the printhead by cleaning it in situ rather than discarding it as waste. The cleaning substance dissolves or removes clogs, allowing the printhead to be reused multiple times, converting a disposable component into a recoverable and regenerable asset.
2Reliability
If purge procedure with pressure is used to clear clogs, then some nozzles may be freed, but ink consumption increases
Solution Approach 1:
The invention changes the parameter of the cleaning substance from traditional ink-based purge solutions to a specialized cleaning composition that is more effective at dissolving clogs at lower concentrations and volumes. This reduces the total amount of substance required while maintaining or improving cleaning effectiveness.
Solution Approach 2:
The invention uses the recirculation system's hydraulic flow to deliver the cleaning substance through the printhead, leveraging the existing fluid dynamics infrastructure. This eliminates the need for high-pressure pneumatic or manual purge procedures that consume excessive ink, using instead the controlled recirculation flow to distribute the cleaning agent efficiently.
3Stability of the object's composition
If recirculation flow is insufficient, then ink aggregation occurs, but increasing flow may cause clogging
Solution Approach 1:
The invention introduces a cleaning substance as an intermediary agent that modifies the ink's properties temporarily during the cleaning cycle. This substance reduces ink viscosity and prevents aggregation, allowing the recirculation system to operate at optimal flow rates without causing clogging, thus maintaining both ink uniformity and nozzle functionality.
Solution Approach 2:
The invention implements periodic cleaning cycles where the recirculation flow rate and cleaning substance concentration are adjusted in stages. During idle periods, lower flow rates prevent aggregation; during active cleaning, higher flow rates clear clogs. This periodic modulation of flow parameters resolves the contradiction between preventing aggregation and avoiding clogging.
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
Effectively clears clogged nozzles without the need for printhead replacement or extensive downtime, while also minimizing ink consumption and maintaining printing operations.
Implementation Method 1
Through the supply line, the ink is provided to each head and made available for printing operations; through the recirculation line, the ink can return to the tank and be advantageously kept moving, avoiding undesired aggregation or drying phenomena given by the stasis of the ink for a prolonged time.
Implementation Method 2
Introducing a substance into the recirculation line (2) at a flow rate Q, such a substance travelling along the recirculation line (2), the head (T), and the supply line (1), identifying a second operating direction D2
Data Source
Figure 1~2
Figure 3~4
AI summary
Cleaning method for a head T, wherein the head T comprises a plurality of nozzles N arranged for dispensing ink and located along a plane P, such a plane P delimiting the head T below; wherein the head T is connected to an ink supply line 1; wherein the head T is further connected to a recirculation line 2, wherein, introducing a substance into the supply line 1, such a substance travels the supply line 1, the head T and the recirculation line 2, identifying a first operating direction D1 and determining a first operating mode; and wherein, in the first operating mode, the substance flows out in part from the head T through the nozzles N in a dispensing direction Y, comprising the steps of: - Interrupting the introduction of the substance into the supply line 1; - Arranging a support 4 having a surface S complementary to the plane P of the head T; - Putting the surface S of the support 4 in contact with the nozzles N; - Keeping said surface S in contact with the nozzles N; - Introducing the substance into the recirculation line 2 at a flow rate Q, such a substance travelling along the recirculation line 2, the head T, and the supply line 1, identifying a second operating direction D2 and determining a second operating mode. - Maintaining said second operating mode for a predetermined cleaning time Tp. A cleaning method for a printing bar 5 comprising a plurality of ink recirculating heads T.