Liquid Ejection Apparatus Pressure Equalization
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Solution Overview
Problem
Existing liquid ejection apparatuses face challenges in simultaneously and efficiently discharging air bubbles and foreign matters from all ejection openings while preventing unnecessary liquid consumption, as the ink pressure in channels takes time to reach the desired level, leading to uneven discharge from ejection openings with varying resistances.
Innovation Solution
The apparatus employs a liquid circulation method to increase internal channel pressure by adjusting channel resistance, ensuring all ejection openings are subjected to high pressure from the start, and uses air communication control to manage pressure within the tank, preventing unnecessary liquid leakage and ensuring consistent discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the ink pressure in the channels is increased to discharge liquid from all ejection openings, then the discharge efficiency of air bubbles and foreign matters is improved, but the liquid is discharged needlessly from ejection openings with low resistance before pressure equalizes
Solution Approach 1:
The patent applies preliminary action by pre-equalizing the pressure in all ink channels before initiating the discharge operation. The pressure equalization process ensures that all ejection openings reach the desired pressure level simultaneously, so when discharge is started, liquid is discharged uniformly from all openings rather than sequentially. This preliminary pressure equalization prevents unnecessary liquid consumption while maintaining high discharge efficiency for air bubbles and foreign matters.
2Stress or pressure
If the pump operates for a long time to build up ink pressure, then the desired pressure is reached, but the liquid leaks from ejection openings during the pressure buildup period
Solution Approach 1:
The patent extracts the harmful effect of liquid leakage by separating the pressure buildup function from the discharge function. During the circulation period, the discharge openings are closed to prevent liquid leakage, while the pump continues to build pressure in the channels. Once the desired pressure is reached, the discharge openings are opened to perform the actual discharge operation. This separation eliminates unnecessary liquid consumption during pressure buildup while maintaining effective discharge capability.
3Productivity
If the ink pressure is increased rapidly to discharge liquid from all ejection openings simultaneously, then the cleaning efficiency is improved, but the pressure control becomes difficult and liquid may be discharged uncontrollably
Solution Approach 1:
The patent uses preliminary pressure equalization to simplify pressure control during the discharge operation. By gradually building pressure in all channels to the desired level before opening the discharge openings, the system ensures that when discharge starts, the pressure is already optimized for simultaneous discharge from all ejection openings. This preliminary preparation eliminates the need for complex real-time pressure control during discharge, making the operation easier and more reliable.
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 approach allows for efficient discharge of thickened liquid, air bubbles, and foreign matters from all ejection openings while minimizing unnecessary liquid consumption and maintaining stable ink supply, ensuring uniform and reliable discharge.
Implementation Method 1
a pump capable of sucking a gas within the third tank provided in a passage other than the first, second and third supply passages
Implementation Method 2
the tank and the ambient air are interrupted from each other in the circulation, thereby producing a negative pressure in the tank
Data Source
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AI summary
A liquid ejection apparatus (101) including: a liquid ejection head (1) including: an inlet opening (72a) into which liquid flows; an outlet opening (73a) from which the liquid having flowed into the inlet opening flows; an inside channel (72,73) communicating the inlet opening and the outlet opening with each other; and a plurality of ejection openings (108) through which is ejected the liquid having flowed through a plurality of individual channels (132) that are branched from the inside channel; a tank (80) storing the liquid to be supplied to the liquid ejection head; an air communication device (88) configured to communicate an inside of the tank with an ambient air or interrupt the communication of the inside of the tank with the ambient air; a supply channel (82) communicating the inside of the tank and the inlet opening with each other; a return channel (83) communicating the inside of the tank and the outlet opening with each other; a supply device (86) configured to supply the liquid in the tank to the inside channel via the supply channel; an adjusting device (87) configured to adjust a channel resistance value of the return channel between a predetermined minimum value and a predetermined maximum value; and a controller (16) configured to control the air communication device, the supply device, and the adjusting device, wherein the controller is configured to perform a liquid circulation control for circulating the liquid through the supply channel, the inside channel, and the return channel in order by controlling (i) the adjusting device such that the channel resistance value is less than the predetermined maximum value and (ii) the supply device to supply the liquid into the inside channel, wherein, when the liquid is circulated by the liquid circulation control, the controller starts a liquid discharge control for discharging the liquid from the plurality of the ejection openings by increasing the channel resistance value to a value larger than the channel resistance value in the liquid circulation control, and wherein the controller controls the air communication device such that the inside of the tank is interrupted from the ambient air in at least a part of a period of the liquid circulation control.