Inkjet Print Head Humidification Control for Ink Viscosity
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Solution Overview
Problem
Inkjet printing apparatuses face issues with ink thickening due to solvent evaporation when the print head is capped, leading to unstable ink ejection and increased ink volume discarded, which affects image quality and running costs.
Innovation Solution
The apparatus employs a control system that adjusts the number and frequency of recovery ejections and humidification ejections based on ambient temperature and humidity to maintain optimal ink conditions within the print head, reducing ink volume ejected to the capping portion and preventing ink thickening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the capping portion is provided with a shielded space to accept discharged ink, then the capping portion can accept thickened ink, but the ejection ports remain in contact with air causing ink to thicken
Solution Approach 1:
A humidification member is introduced as an intermediary element within the shielded space to maintain appropriate humidity levels. This mediator prevents direct contact between the ink and dry air, thereby preventing ink thickening while preserving the ink acceptance function of the capping portion.
Solution Approach 2:
The shielded space creates an inert environment by isolating the ink from external air. Combined with the humidification member, this inert atmosphere maintains stable ink composition by preventing evaporation and thickening during the standby period.
2Stability of the object's composition
If continuous ejection is performed based on humidity prediction, then ink thickening is reduced, but the volume of ink discarded increases
Solution Approach 1:
Instead of continuous ejection, the system performs periodic humidification ejections based on predicted humidity levels. This periodic action maintains ink humidity stability while significantly reducing the total volume of ink discarded compared to continuous ejection methods.
Solution Approach 2:
The system uses humidity sensors to monitor ink humidity levels and provides feedback to the control unit. Based on this feedback and predicted humidity trends, the system adjusts the timing and frequency of humidification ejections, optimizing ink usage while maintaining ink composition stability.
3Weight of stationary object
If the capping portion shares the ink accepting function, then the apparatus body size is reduced, but the ejection ports are exposed to air in the shielded space
Solution Approach 1:
The humidification member serves as an intermediary that reconciles the conflicting requirements. It allows the capping portion to maintain both its ink acceptance function and its protective shielding function, preventing harmful air contact while preserving the compact apparatus design.
Solution Approach 2:
The system changes the humidity parameter within the shielded space to prevent ink thickening. By actively controlling the humidity environment rather than relying solely on physical isolation, the system maintains ink quality while preserving the compact shared capping structure.
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 maintains ejection performance, suppresses ink volume, and reduces running costs associated with ink usage while ensuring excellent image quality by effectively managing ink humidity and viscosity during standby periods.
Implementation Method 1
an ejection energy generation element, such as an electrothermal transducer or an electromechanical transducer, is arranged in a liquid path that is in communication with the ejection ports
Implementation Method 2
Some of the inks used for printing use water as a solvent, and when exposed to the air, the water serving as the solvent evaporates to cause an increase in viscosity (thickening of the ink)
Data Source
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AI summary
There is provided an inkjet printing apparatus capable of performing a printing operation to eject ink from an ejection port provided for a print head to a print medium while covering the ejection port with a capping portion in a standby state in which the printing operation is not performed, the apparatus including: a humidifying unit configured to perform a humidification operation to humidify a space formed between the capping portion and the print head in the standby state; and a control unit configured to cause the humidifying unit to perform the humidification operation on the space in the standby state, wherein the control unit suspends the humidification operation at a predetermined timing after performing the humidification operation multiple times.