Encoder Signal Multiplication for Inkjet Discharge Timing
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Solution Overview
Problem
Inkjet printers face issues with inconsistent ink discharge due to contaminants on encoder components, leading to irregular pulse signal periods and subsequent variations in ink discharge intervals.
Innovation Solution
A liquid discharge apparatus with a controller that generates multiplied signals based on detection signals from encoder slits, adjusting the signal generation rate according to changes in signal periods and contaminants presence, ensuring appropriate timing for ink discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an encoder is used to control ink discharge timing based on sheet conveying amount, then discharge timing can be controlled, but contaminants attach to the encoder causing signal period changes and discharge interval variations
Solution Approach 1:
The patent applies preliminary action by pre-calculating the number of encoder pulses that should occur in each discharge interval based on standard conveyance conditions. The controller stores these predetermined pulse counts and uses them to verify whether the actual number of pulses matches the expected number, thereby compensating for timing variations caused by encoder contamination before they affect discharge accuracy.
Solution Approach 2:
The patent implements feedback by continuously monitoring the actual number of encoder pulses occurring between liquid discharge operations and comparing this count against the predetermined standard number of pulses. When a discrepancy is detected due to encoder contamination or conveyance variations, the system uses this feedback information to adjust subsequent discharge timing, maintaining accurate discharge intervals despite encoder degradation.
2Productivity
If the print head and sheet are relatively moved by conveyor rollers to enable discharge, then continuous printing is achieved, but encoder signal periods change when contaminants are present causing discharge interval variations
Solution Approach 1:
The patent applies preliminary action by pre-establishing the expected number of encoder pulses for each discharge interval under normal operating conditions. This predetermined standard serves as a reference for verifying whether the actual pulse count during continuous printing matches the expected value, enabling the system to detect and compensate for timing variations caused by encoder contamination while maintaining continuous printing operation.
Solution Approach 2:
The patent implements feedback by monitoring the actual encoder pulse count during continuous printing operations and comparing it against the predetermined standard pulse count. When contaminants cause the actual pulse number to deviate from the standard, this feedback mechanism triggers adjustments to maintain correct discharge intervals, ensuring manufacturing precision is preserved despite the challenges of continuous printing with potential encoder contamination.
3Device complexity
If pulse signals from the encoder are used directly to control discharge timing, then simple control is achieved, but signal period changes due to contaminants cause inappropriate discharge timing
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the standard number of encoder pulses that should occur between discharge operations under normal conditions. This predetermined reference value is established before actual printing begins, creating a baseline for comparing actual pulse counts and detecting timing variations caused by encoder contamination without adding complex real-time calculation requirements.
Solution Approach 2:
The patent implements feedback by counting the actual number of encoder pulses between discharge operations and comparing this count against the predetermined standard number. When contaminants cause the actual pulse count to differ from the standard, this feedback loop enables the system to detect the timing error and adjust subsequent discharge timing accordingly, maintaining measurement precision while building upon the simple pulse signal control foundation.
Data Source
AI summary
A liquid discharge apparatus includes a liquid discharge head, a carriage which has the liquid discharge head mounted thereto and moves in a scanning direction, an encoder sensor mounted to the carriage, a slit member extending in the scanning direction and having encoder slits aligned in the scanning direction and detected by the encoder sensor, and a controller. The controller moves the carriage in the scanning direction, generates multiplied signals by multiplying a detection signal obtained based on a detection result of the encoder slits by the encoder sensor when a signal change occurs in the detection signal, and causes the liquid discharge head to discharge liquid from nozzles, based on the multiplied signals.