Print Head Controller Timing Quantization
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Solution Overview
Problem
Variations in the transport velocity of a recording medium cause fluctuations in the activation timing of print heads in inkjet printing devices, leading to negative effects on print quality due to degraded droplet formation at certain operating frequencies.
Innovation Solution
A controller for print heads that detects line signals based on transport velocity, determines activation points in time using quantized operating frequencies, and adjusts these points to minimize accumulated quantization errors, ensuring operation within a set of predefined frequencies that maintain high-quality droplet formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the print head activation timing is adjusted to compensate for transport velocity fluctuations, then print quality is improved, but device complexity increases due to the need for continuous timing adjustment and quantization error management
Solution Approach 1:
The system changes the operating frequency parameter of the print head by selecting from a set of quantized frequencies. The controller adjusts the activation timing based on detected transport velocity and accumulates quantization errors to determine optimal frequency switches, thereby maintaining print quality while managing complexity through discrete parameter changes rather than continuous adjustment
Solution Approach 2:
The system implements feedback by detecting the actual transport velocity of the recording medium and using this information to adjust the print head activation timing. The controller continuously monitors timing deviations and accumulates quantization errors to determine when frequency changes are needed, creating a closed-loop control system that maintains precision
2Manufacturing precision
If quantized operating frequencies are used to stabilize droplet formation, then print quality is improved, but registration errors accumulate over time
Solution Approach 1:
The controller detects actual transport velocity and compares it with expected values to determine timing deviations. By accumulating these deviations as quantization errors and using feedback to adjust future activation timings, the system compensates for registration errors that would otherwise accumulate from using fixed quantized frequencies
Solution Approach 2:
The system dynamically adjusts the operating frequency of the print head based on accumulated quantization errors and detected transport conditions. Rather than sticking to a single fixed frequency, the controller switches between quantized frequencies to optimize both droplet formation quality and registration accuracy over time
3Productivity
If the print head operates at higher frequencies to increase productivity, then printing speed is improved, but droplet formation quality deteriorates at certain frequencies
Solution Approach 1:
The system changes the operating frequency parameter by selecting from a predefined set of quantized frequencies that are known to produce high-quality droplets. The controller adjusts the frequency based on transport velocity and accumulated errors, ensuring that only frequencies compatible with quality droplet formation are used, thereby maintaining productivity while preventing quality deterioration
Solution Approach 2:
The system creates a template or copy of optimal operating conditions by using quantized frequencies that have been predetermined to produce high-quality droplets. Rather than continuously varying frequency, the system selects from discrete copies of proven optimal frequencies, ensuring consistent droplet formation quality while maintaining high printing speed
Data Source
AI summary
A controller for operating a print head is described, which controller is designed to shift the activation points in time of the print head for printing of different lines of a print image on a recording medium relative to the line signal points in time, said line signal points in time being dependent on the transport velocity of the recording medium, such that the print head is operated with quantized operating frequencies from a set of predefined quantized operating frequencies. The print quality of the print head may thus be increased.