Inkjet Head Humidity Control for Ejection Stability
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Solution Overview
Problem
Inkjet recording apparatuses face issues with ink viscosity increase due to drying on the nozzle surface, leading to ejection defects, and dew condensation caused by humidity, which existing solutions do not adequately address.
Innovation Solution
An inkjet recording apparatus with a humidity acquisition system that regulates the relative humidity of the nozzle surface between 37% RH and 65% RH, using temperature and humidity sensors to perform humidification or dehumidification processes, and a fan for air blowing to maintain optimal humidity levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the humidity of the nozzle surface is increased to prevent ink drying, then ink viscosity is maintained within proper range, but dew condensation occurs on the nozzle surface causing adverse effects on ink ejection
Solution Approach 1:
The patent applies parameter changes by precisely controlling the humidity parameter within a specific range (37% to 65% RH) rather than simply increasing or decreasing it. This optimized parameter range prevents both ink drying (by maintaining sufficient humidity) and dew condensation (by limiting maximum humidity), thereby resolving the technical contradiction between preventing ink viscosity increase and avoiding dew condensation harmful effects
Solution Approach 2:
The patent implements feedback control through a humidity sensor that continuously monitors the actual humidity on the nozzle surface and compares it with the target range. Based on this feedback, the control unit adjusts the humidifier and dehumidifier operations to maintain humidity within the optimal range, dynamically preventing both drying and dew condensation conditions
2Loss of substance
If the relative humidity is set to 60% RH or more to prevent solvent evaporation, then ink viscosity deterioration is prevented, but dew condensation occurs on the nozzle surface
Solution Approach 1:
The patent refines the humidity parameter from the conventional minimum threshold of 60% RH to a more precise optimal range of 37% to 65% RH. This parameter optimization allows sufficient humidity to prevent solvent evaporation while establishing an upper limit that prevents dew condensation, thereby resolving the contradiction between preventing substance loss and avoiding harmful condensation effects
3Reliability
If the inkjet head is housed in a cap to wet the nozzle surface, then ink ejection is maintained, but the humidity cannot be precisely controlled leading to dew condensation
Solution Approach 1:
The patent transforms the simple capping method into a feedback-controlled humidity regulation system. The humidity sensor provides continuous monitoring of the actual humidity conditions inside the cap, and the control unit adjusts humidifier and dehumidifier operations based on this feedback to maintain humidity within the optimal range, thereby achieving precise humidity control while maintaining ink ejection reliability
Solution Approach 2:
The cap structure is enhanced with multiple functions: it not only provides physical protection and basic humidity maintenance like traditional caps, but also serves as a controlled environment for humidity regulation through integrated humidifier and dehumidifier systems. This multi-functional approach resolves the contradiction between maintaining ink ejection and achieving precise humidity control
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 ejection defects caused by both drying and dew condensation, ensuring stable ink ejection performance by maintaining the nozzle surface humidity within a specific range.
Implementation Method 1
a humidity acquiring part configured to acquire a relative humidity of the nozzle surface
Implementation Method 2
perform at least one of a humidification process and a dehumidification process
Implementation Method 3
perform at least one of a humidification process and a dehumidification process
Implementation Method 4
a fan for air blowing to maintain optimal humidity levels
Data Source
AI summary
A control method for an inkjet recording apparatus includes: a head housing step of housing in a head housing part an inkjet head having a nozzle surface on which nozzles configured to eject an ink are formed; a humidity acquiring step of acquiring a relative humidity of the nozzle surface of the inkjet head housed in the head housing part; and a temperature and humidity regulating step of performing at least one of a humidification process and a dehumidification process according to the relative humidity of the nozzle surface acquired in by the humidity acquiring step to set the relative humidity of the nozzle surface to 37% RH or more and 65% RH or less.