Inkjet Head Voltage Correction for Border Density Uniformity
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Solution Overview
Problem
Ink jet printing apparatuses with vertically arranged ink jet heads experience uneven density and misalignment of ink droplet landing positions due to gravity, leading to white streaking and increased adjustment time when correcting drive voltages to compensate for density differences.
Innovation Solution
A method and apparatus that corrects drive voltages and determines nozzles to be driven after voltage adjustment for adjacent ink jet heads, using a drive voltage correcting unit and driven nozzle determining unit to suppress density unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If drive voltage is corrected to compensate for density differences among ink jet heads, then density uniformity is improved, but landing position shifts occur due to changes in droplet flying speed
Solution Approach 1:
The patent applies preliminary action by calculating and storing the relationship between drive voltage corrections and landing position shifts before actual printing. The system pre-determines compensation amounts for different voltage correction levels, so when density correction is applied, the corresponding landing position compensation is automatically applied without real-time calculation delays.
Solution Approach 2:
The patent changes multiple parameters simultaneously - both the drive voltage parameter and the overlap parameter are adjusted together. When correcting density differences by changing drive voltage, the system also changes the overlap parameter to compensate for the resulting landing position shifts, maintaining both density uniformity and positional accuracy.
2Manufacturing precision
If drive voltage of lower ink jet head is increased to correct density difference, then density uniformity is improved, but landing position shifts upward due to increased ejection speed
Solution Approach 1:
The system pre-calculates and stores the relationship between drive voltage corrections and required overlap adjustments. This preliminary action eliminates the need for manual iterative adjustment, as the correct overlap parameter is automatically determined based on the applied voltage correction.
Solution Approach 2:
The patent implements a feedback mechanism where the system monitors density differences, applies voltage corrections, and automatically adjusts the overlap parameter based on pre-stored compensation data. This closed-loop feedback ensures that both density uniformity and landing position accuracy are maintained without manual intervention.
3Measurement precision
If overlap amount is adjusted after drive voltage correction, then landing position alignment is improved, but adjustment time and effort increase
Solution Approach 1:
The patent stores pre-calculated compensation data that maps drive voltage corrections to required overlap adjustments. This preliminary preparation allows the system to automatically determine the correct overlap parameter immediately when voltage correction is applied, eliminating time-consuming manual adjustment iterations.
Solution Approach 2:
The system performs self-adjustment by automatically selecting the appropriate overlap parameter based on the applied drive voltage correction and pre-stored compensation data. This self-service capability eliminates the need for operator intervention in the adjustment process, significantly reducing adjustment time.
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
Suppresses density unevenness and simplifies the nozzle adjustment process by determining nozzles after drive voltage correction, reducing maintenance effort and time.
Implementation Method 1
the landing positions of ink droplets will be shifted downward due to the effect of gravity
Implementation Method 2
a drive voltage correcting unit that applies a drive voltage to each of the ejection heads and corrects the drive voltages for ejection heads which are adjacent to each other in the array direction of the nozzles based on a density difference between the adjacent ejection heads
Data Source
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AI summary
[Objective] To provide a method and apparatus for controlling liquid ejection that suppresses unevenness in density at borders between ink jet heads. [Constitution] A liquid ejection control apparatus includes: a head (10) in which a plurality of ejection heads (16) having an array of nozzles (17) that eject droplets perpendicularly onto a printing surface (Ps) which is inclined with respect to the horizontal plane, the plurality of ejection heads (16) being arranged in an array direction of the nozzles (17); a drive voltage correcting unit (53) that applies a drive voltage to each of the ejection heads (16) and corrects the drive voltages for ejection heads (16) which are adjacent to each other in the array direction of the nozzles (17) based on a density difference between the adjacent ejection heads (16); and a driven nozzle determining unit (54) that determines a nozzle (17) to be driven in each ejection head (16) in an overlap region between the adjacent ejection heads (16). The determination of the nozzle (17) to be driven by the driven nozzle determining unit (54) is performed after correction of the drive voltage by the drive voltage correcting unit (53).