Ink Circulation Control Before Recovery in Inkjet Printheads
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Solution Overview
Problem
Inkjet printing apparatuses face issues with ink viscosity increase in ejection ports due to evaporation, leading to color mixing and foreign substance entry during recovery operations, which can cause image abnormalities and decreased productivity.
Innovation Solution
A printing apparatus that circulates ink through ejection ports to maintain ink flow and suppress viscosity, with controlled stop and wait times to prevent ink and foreign substances from entering circulation passages during recovery operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the circulation drive is stopped after print operation completion before recovery operation, then color mixing ink and foreign substances can be prevented from entering deep into flow passages, but productivity decreases due to delay in recovery operation start
Solution Approach 1:
The circulation drive is stopped in advance before the recovery operation starts, creating a time margin that allows the ink flow velocity to naturally decrease to an acceptable level. This preliminary stop prevents color mixing and foreign substance ingress while still allowing timely recovery operations by accounting for the flow decay time in the overall timing schedule.
Solution Approach 2:
The system utilizes the natural dynamic decay of ink flow velocity after circulation stoppage. Instead of requiring immediate stoppage at recovery start, the system allows the flow velocity to dynamically decrease over time, and schedules the circulation stop to occur early enough that this natural decay process completes before recovery begins.
2Productivity
If the circulation drive continues during recovery operation, then productivity is maintained with no delay, but color mixing ink and foreign substances enter deep into circulation passages causing image abnormalities
Solution Approach 1:
The circulation drive is stopped in advance before the recovery operation starts, creating a time margin that allows the ink flow velocity to naturally decrease to an acceptable level. This preliminary stop prevents color mixing and foreign substance ingress while still allowing timely recovery operations by accounting for the flow decay time in the overall timing schedule.
3Reliability
If wait time is provided for circulation flow velocity to stop after print completion, then color mixing is prevented, but productivity decreases due to delayed recovery operation
Solution Approach 1:
The circulation drive is stopped in advance before the recovery operation starts, creating a time margin that allows the ink flow velocity to naturally decrease to an acceptable level. This preliminary stop prevents color mixing and foreign substance ingress while still allowing timely recovery operations by accounting for the flow decay time in the overall timing schedule.
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 prevents ink and foreign substances from entering circulation passages, maintaining ejection characteristics and reducing productivity losses while ensuring high-quality image production.
Implementation Method 1
a flow of the ink is generated to pass through the pressure chambers by using a pressure difference between two pressure adjustment mechanisms
Implementation Method 2
ink is circulated to pass through flow passages communicating with ejection ports arranged at high density and through pressure chambers corresponding to the ejection ports to suppress an increase in viscosity of the ink in the ejection ports
Data Source
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AI summary
A printing apparatus (101) includes: an ejection unit (110) configured to perform a print operation of forming an image on a print medium (103) by ejecting liquid from an ejection port by using drive of an ejection energy generation element (423) provided in a pressure chamber (424), the liquid flowing into the pressure chamber from a first flow passage (431); a circulation unit (408) configured to circulate the liquid in a circulation flow passage including the first flow passage, the pressure chamber, and a second flow passage (432) configured to allow the liquid in the pressure chamber to flow to an outside of the pressure chamber; a recovery unit (210) configured to perform a recovery operation of the ejection unit; and a control unit (301) configured to stop the circulation unit before completion of the print operation by the ejection unit in the case where the recovery operation is to be performed after the print operation.