Thermal Head Heat Accumulation Correction via Next-Line Data
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Solution Overview
Problem
Existing accumulated-heat correction methods for thermal heads in printers fail to accurately achieve desired print densities, particularly when correcting for residual heat, leading to incomplete or incorrect print densities in subsequent lines.
Innovation Solution
An accumulated-heat correction apparatus and method that calculates cumulative data from previous lines and next-line data to generate correction data for the current line, allowing for precise control of thermal head conduction time to ensure accurate print densities across all lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the conduction time is decreased to correct accumulated heat, then the print density accuracy is improved, but the correction becomes insufficient when the calculated correction exceeds available time range
Solution Approach 1:
The patent applies preliminary action by calculating and storing correction values for all possible conduction time combinations before actual printing. The correction lookup table is pre-computed based on thermal head characteristics, enabling the system to quickly retrieve appropriate corrections without real-time calculation, thus ensuring both accuracy and reliability even at line boundaries.
Solution Approach 2:
The patent transitions from one-dimensional correction (based only on current line conduction time) to two-dimensional correction by incorporating the conduction time of the next line into the correction calculation. This dimensional expansion allows the system to anticipate and compensate for heat accumulation effects that would otherwise spill over into subsequent lines, resolving the boundary correction insufficiency problem.
2Temperature
If the conduction time of the thermal head is subtracted to correct accumulated heat, then the temperature rise is reduced, but the conduction time becomes less than zero which is not physically possible
Solution Approach 1:
The system pre-calculates correction values within the valid conduction time range and stores them in a lookup table. When correction is needed, the system retrieves pre-computed values rather than calculating negative corrections, ensuring that all corrections remain physically feasible while still effectively reducing temperature rise.
Solution Approach 2:
The patent applies partial correction when the full correction would exceed available time range. Instead of attempting to apply the complete calculated correction (which would be negative), the system applies the maximum feasible correction within the valid time range, accepting that some correction may be partial but ensuring operational feasibility.
3Stability of the object's composition
If the conduction time is adjusted for accumulated heat correction, then the print density uniformity is improved, but the correction accuracy decreases at line boundaries
Solution Approach 1:
The patent enhances correction accuracy at line boundaries by incorporating the next line's conduction time into the correction calculation. This creates a two-dimensional correction model that accounts for heat accumulation effects spanning line boundaries, thereby maintaining both density uniformity and correction accuracy even at transition points.
Solution Approach 2:
The system uses feedback from next-line data to adjust current line corrections. By anticipating the thermal state of the next line and incorporating it into the correction calculation, the system creates a feedback mechanism that prevents correction errors at line boundaries, maintaining both uniformity and precision throughout the entire print sequence.
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
This approach enables the attainment of desired print densities by considering next-line data in the correction process, resulting in high-quality prints with improved image quality by adjusting the conduction time to account for uncorrectable heat in previous lines.
Implementation Method 1
a thermal head comes to have a heat quantity corresponding to the conduction time
Implementation Method 2
heat is accumulated in the thermal head, so that when a current is conducted through the thermal head for equal time periods, a temperature rise corresponding to accumulated heat A occurs
Data Source
AI summary
An accumulated-heat correction apparatus for a thermal head, wherein print data of each line are outputted to the thermal head, and a conduction time of the thermal head is controlled on the basis of the print data, includes cumulative-data calculation means for calculating cumulative data which is ascribable to accumulated heat of the thermal head up to a previous line (n−1), next-line data calculation means for calculating print data of a next line (n+1), correction-data generation means for calculating correction data (ΔTs) which corrects print data of a current line n, by using the cumulative data and the next-line data, and head control means for controlling the conduction time of the thermal head on the basis of the correction data (ΔTs) which has been generated by the correction-data generation means.