Liquid Ejection Apparatus Cap Mechanism Purging
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Solution Overview
Problem
In liquid ejection apparatuses, air bubbles and high-viscosity ink can be sucked back into ejection openings during the cleaning process, leading to ejection failures due to negative pressure applied after the cleaning operation.
Innovation Solution
A liquid ejection apparatus with a cap mechanism that isolates the ejection space from the outside space, allowing for a controlled purging operation where the ejection space is switched from a first isolated state to a second isolated state, creating a negative pressure that prevents ink from being sucked back into the ejection openings, and a controller that manages the cap mechanism and pump to perform the purging operation effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pump is driven to apply pressure to ink in head passages for ejection opening cleaning, then air bubbles and high-viscosity ink are discharged from ejection openings, but the discharged air bubbles and high-viscosity ink may be attached to the ejection openings
Solution Approach 1:
The patent divides the cleaning process into two distinct phases: a first cleaning mode where the discharge passage is closed and pump pressure forces ink out to remove blockages, and a second cleaning mode where the discharge passage is opened and negative pressure suction removes discharged debris. This segmentation prevents the harmful effect of debris re-attaching to ejection openings by immediately transitioning to a removal phase after the discharge phase.
Solution Approach 2:
The patent applies reverse action by switching from a positive pressure discharge mode to a negative pressure suction mode. After the pump discharges ink and debris under positive pressure, the system inverts the pressure differential by opening the discharge passage to atmosphere and using suction to pull the discharged debris away from the ejection openings, preventing re-attachment.
2Ease of operation
If negative pressure is applied to ink in the head by head difference after ejection opening cleaning, then ink flows from ejection openings into the head, but this causes ejection failure due to air bubbles and high-viscosity ink being present
Solution Approach 1:
The patent performs preliminary cleaning action by discharging ink under pressure before applying negative pressure. The first cleaning mode forcibly removes air bubbles and high-viscosity ink from the head passages and ejection openings before the second cleaning mode applies negative pressure. This preliminary discharge ensures that when negative pressure is subsequently applied, there is minimal debris to be drawn back into the ejection openings.
Solution Approach 2:
The patent maintains continuous cleaning action by transitioning from the first cleaning mode (pressure discharge) to the second cleaning mode (negative pressure suction) without interruption. The discharge passage is continuously managed - first closed for pressure buildup and discharge, then opened for suction - ensuring that the useful cleaning action continues throughout both phases without allowing debris to settle or re-attach.
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
Prevents ink and foreign matters from being sucked into the ejection openings after purging, reducing the likelihood of ejection failures and ensuring reliable ink ejection.
Implementation Method 1
an elastic member which substantially isolates the ejection space from an outside space by enclosing the ejection space and the plurality of ejection openings with the facing member and the ejection surface
Implementation Method 2
the cap mechanism being configured to switch a state of the ejection space selectively to one of: a first isolated state in which the ejection space is isolated from the outside space by the elastic member; a second isolated state in which the ejection space is isolated from the outside space by the elastic member in a state in which the facing member is spaced apart from the ejection surface by a greater distance than in the first isolated state
Implementation Method 3
a first pump configured to supply the liquid from the first tank to the internal passage via the first supply passage
Data Source
AI summary
A liquid ejection apparatus includes: a head including an ejection surface, an internal passage and ejection openings; a cap mechanism including a facing member and an elastic member; and a controller for: performing an ejection-opening purging operation for, after establishing a first isolated state of an ejection space, discharging liquid from the ejection openings by establishing an isolating state of a discharge passage in a state in which the liquid in a tank is supplied to the internal passage by a pump; and thereafter stopping the liquid in the tank from being supplied to the internal passage. The controller controls the cap mechanism in the ejection-opening purging operation to switch the ejection space from the first isolated state to a second isolated state in which the ejection space is isolated, with the facing member spaced from the ejection surface at a greater distance than in the first isolated state.