Check Valve and Atmosphere Opening Prevent Air Bubbles in Ink Cap
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Solution Overview
Problem
In image forming apparatuses, the generation of air bubbles in the cap during the maintenance and recovery process can lead to ink adhesion on the nozzle face, causing color mixture and image degradation, especially when the negative pressure is weakened.
Innovation Solution
The implementation of a check valve in the discharge path and an atmosphere opening part that communicates with the cap at a position higher than the liquid surface, along with a suction pump made of a tube pump, prevents air from entering the cap and reduces the likelihood of air bubbles forming, thereby maintaining ink purity and preventing color mixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the suction pump is driven to discharge ink from the cap, then the ink discharge function is improved, but air bubbles may enter the cap through the discharge path causing ink adhesion and color mixture
Solution Approach 1:
A check valve is introduced as an intermediary component in the discharge path between the suction pump and the cap. The check valve allows ink to flow from the cap to the suction pump during suction operations while preventing air from entering the cap when the pump is not actively suctioning, thus resolving the contradiction between maintaining reliable ink discharge and preventing harmful air bubble entry.
Solution Approach 2:
The cap is designed with an airtight space that maintains a controlled environment. By using the check valve to prevent air ingress and the atmosphere opening part to control deliberate air intake, the system maintains an inert-like environment within the cap that prevents unwanted air-ink interactions and bubble formation during suction operations.
2Productivity
If the cap is sealed to create an airtight space, then ink suction efficiency is improved, but air trapped inside cannot escape causing pressure buildup and suction failure
Solution Approach 1:
The atmosphere opening part is designed to open the airtight space to the atmosphere in advance before suction operations begin or when pressure buildup is detected. This preliminary action prevents pressure buildup that would otherwise hinder suction efficiency, while the check valve ensures that this atmospheric opening does not allow air to enter during active suction when the valve is closed.
3Ease of operation
If the atmosphere opening part is positioned at the top of the cap, then air bubbles can escape easily, but liquid ink may leak out during suction operations
Solution Approach 1:
The check valve acts as an intermediary that controls fluid flow direction. Positioned in the discharge path, it allows ink to be discharged from the cap to the pump while preventing reverse flow. Combined with the atmosphere opening part positioned at the top, this arrangement enables air bubbles to escape through the top opening while the check valve prevents ink from following air out during suction operations.
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 effectively prevents air bubbles from forming in the cap, ensuring that ink of different colors does not mix and adhere to the nozzle face, thereby maintaining image quality and preventing degradation during the printing process.
Implementation Method 1
when the negative pressure is weakened
Implementation Method 2
A check valve configured to prevent a flow of the liquid toward the cap from the suction pump is provided in the discharge path
Implementation Method 3
an atmosphere opening part configured to open an airtight space, created when the nozzle face is capped by the cap, to the atmosphere
Data Source
AI summary
An image forming apparatus includes a recording head configured to have a nozzle face on which nozzles that discharge liquid droplets are formed; a cap configured to cap the nozzle face of the recording head; a discharge path configured to be connected to the cap; a suction pump configured to be provided in the discharge path and be made of a tube pump; and an atmosphere opening part configured to open an airtight space, created when the nozzle face is capped by the cap, to the atmosphere. The atmosphere opening part is configured to communicate with the inside of the cap at a position higher than a surface of liquid discharged into the cap, and a check valve configured to prevent a flow of the liquid toward the cap from the suction pump is provided in the discharge path.