Liquid Ejection Head Temperature Control via Ink Circulation
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Solution Overview
Problem
Liquid ejection heads experience temporary temperature changes and increased power consumption due to preliminary ejections during temperature adjustment operations, especially in page-wide type heads with numerous ejection ports, leading to potential printing failures and image quality deterioration.
Innovation Solution
A liquid ejection head design that circulates ink between a buffer tank and the ejection head, using a thermal system to generate air bubbles for ejection, and incorporates a negative-pressure control unit to maintain constant pressure, reducing the need for preliminary ejections and minimizing temperature fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If preliminary ejections are performed during temperature adjustment operation, then liquid viscosity is reduced and ejection smoothness is improved, but head temperature temporarily decreases and power consumption increases
Solution Approach 1:
The patent applies preliminary action by performing preliminary ejections before the formal recording operation begins. The control unit executes a predetermined number of preliminary ejections (e.g., 1-5 times) for each nozzle group before actual printing, which warms up the liquid and reduces viscosity in advance, ensuring smooth ejection during recording without causing temperature drops during the actual printing process.
Solution Approach 2:
The patent implements periodic action by dividing the ejection operation into distinct phases: preliminary ejection phase and formal recording phase. The control unit periodically performs preliminary ejections at specific intervals (before recording, and occasionally during recording based on predetermined conditions) rather than continuously, thereby managing temperature and power consumption while maintaining ejection reliability.
2Reliability
If preliminary ejections are performed frequently, then liquid viscosity is reduced and ejection reliability is improved, but power consumption increases and printing speed decreases
Solution Approach 1:
The patent applies partial action by performing preliminary ejections only for specific nozzle groups that require it, rather than for all nozzles continuously. The control unit determines which nozzle groups need preliminary ejections based on predetermined conditions (e.g., number of continuous non-ejection periods, temperature thresholds) and performs preliminary ejections only for those groups, reducing the overall impact on printing speed while maintaining ejection reliability where needed.
Solution Approach 2:
The patent performs preliminary ejections in advance before formal recording operations begin, and occasionally during recording based on predetermined conditions. By executing preliminary ejections proactively rather than reactively, the system ensures ejection reliability is maintained without requiring frequent interruptions during the actual printing process, thereby minimizing impact on printing speed.
3Productivity
If page-wide type liquid ejection head with multiple recording element substrates is used, then printing speed is improved, but temperature adjustment becomes more complex and power consumption increases
Solution Approach 1:
The patent divides the page-wide liquid ejection head into multiple independent nozzle groups, each corresponding to a recording element substrate. The control unit can independently control preliminary ejections for each nozzle group based on their specific conditions (e.g., number of continuous non-ejection periods, temperature status). This segmentation allows selective temperature management and preliminary ejection execution for individual substrates, reducing overall system complexity while maintaining high-speed printing capability.
Solution Approach 2:
The patent applies partial action by performing preliminary ejections only for specific nozzle groups that meet predetermined conditions, rather than for all nozzles in the page-wide head. The control unit evaluates each nozzle group independently and executes preliminary ejections only where necessary, reducing power consumption and operational complexity while maintaining printing speed advantages of the page-wide configuration.
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 suppresses temporary temperature changes and power consumption increases, enabling high-quality, high-speed printing with reduced preliminary ejections, thus improving the reliability and efficiency of the liquid ejection process.
Implementation Method 1
a heating unit that heats the liquid
Implementation Method 2
a pressure chamber in which an energy generating element that generates energy used for ejecting the liquid from the ejection port is disposed
Data Source
AI summary
A liquid ejection head includes a nozzle including an ejection port for ejecting a liquid for performing recording on a recording medium, and a pressure chamber in which an energy generating element that generates energy used for ejecting the liquid from the ejection port is disposed; and a heating unit that heats the liquid. In the liquid ejection head, the liquid in the pressure chamber is circulated to and from the outside of the pressure chamber, and an average number of preliminary ejections per nozzle during an operation period in which the recording is performed is equal to or greater than 0 and equal to or less than 20.