Dot Clock Signal Chain Synchronization for Printer Color Alignment
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Solution Overview
Problem
In color printers, transport slips or hesitations cause dot clock generators to prematurely operate printheads, leading to misalignment of ink pixels and improper color hues due to lack of compensation for timing delays.
Innovation Solution
A method synchronizes dot clock signal generators by using encoder and dot clock count parameters to ensure accurate timing, with a chain of generators counting pulses and generating signals only when predetermined values are reached, compensating for transport delays and misalignments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dot clock generators count clock signals continuously to synchronize with substrate arrival, then timing synchronization is improved, but transport slips cause premature ejector operation and pixel misalignment
Solution Approach 1:
The system uses encoder feedback to monitor actual media transport position and adjusts dot clock signal generation accordingly. The encoder provides real-time positional feedback that allows the system to compensate for transport variations and prevent premature ejector operation, resolving the contradiction between continuous timing synchronization and pixel alignment precision.
Solution Approach 2:
The system dynamically adjusts the dot clock signal parameters based on encoder feedback. When transport slip is detected, the system modifies the dot clock timing parameters to compensate for the discrepancy, ensuring that ejectors operate at the correct moment despite transport variations, thereby maintaining pixel alignment precision.
2Device complexity
If dot clock generators operate independently in multiple color stations, then device complexity is reduced, but timing delays cause color hue errors
Solution Approach 1:
The system merges the timing reference function across all color stations by using a common encoder feedback mechanism. While each color station has its own dot clock generator, they all reference the same encoder-based timing signal, effectively combining their synchronization sources. This maintains relatively simple individual station design while ensuring consistent timing across all stations to prevent color hue errors.
3Manufacturing precision
If the system compensates for transport slips by adjusting dot clock timing, then pixel alignment is improved, but system complexity increases
Solution Approach 1:
The encoder serves as an intermediary device that mediates between the media transport system and the dot clock generators. Rather than directly complexifying the dot clock generation system, the patent introduces the encoder as an intermediate sensing and feedback component that provides positional information, allowing compensation to be implemented through signal processing rather than mechanical complexity.
Data Source
AI summary
A printer includes a plurality of dot clock signal generators, each of which generates dot clock signals for operating ejectors in a printhead in a color station of the printer. The dot clock signal generators are connected in a chain that corresponds to the process direction of the color stations in the printer. Each dot clock signal generator is configured to count dot clock signals of a preceding dot clock signal generator in the chain or a reference clock generator to determine when the dot clock signal generator turns on and to count encoder signals corresponding to movement of a substrate through the printer to determine when to generate dot clock signals for a color station.