Duplex Printing Correction Using Surface-Specific Roller Speed Data
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Solution Overview
Problem
Existing printing apparatuses face challenges in achieving high-speed duplex printing with precise image size on both surfaces of a sheet due to differences in friction coefficients and measurement delays, leading to image size discrepancies and reduced printing speed.
Innovation Solution
A printing apparatus with a sheet feeding unit, conveying mechanism, printing unit, reverse unit, and control unit that acquires and corrects rotation and movement information to adjust driving control of print heads and rollers, allowing for different correction data to be used for each surface during duplex printing, thereby maintaining high-quality and high-speed printing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same correction is performed in printing on the first surface and on the second surface, then the printing process is simplified, but the image on the second surface has a size different from the originally intended size
Solution Approach 1:
The patent applies different correction data for the first surface and second surface of the sheet. The control unit stores and applies first correction data when printing on the first surface and second correction data when printing on the second surface, accounting for the different friction coefficients and slippage characteristics of each surface.
2Measurement precision
If a laser Doppler sensor is used to measure sheet speed, then real-time speed measurement is achieved, but delay in detection due to complicated signal processing limits the printing speed
Solution Approach 1:
The patent replaces the laser Doppler sensor with a different type of sensor that does not require complicated signal processing. This alternative sensor achieves real-time speed measurement without the processing delays that limit printing speed in laser Doppler systems.
3Object-affected harmful factors
If the distance between the speed sensor and the print heads is reduced, then the likelihood of ink mist deposition on the sensor is reduced, but it becomes more difficult to complete calculation and control of ink ejection timing
Solution Approach 1:
The patent uses a different sensor system that does not require complex real-time calculations, enabling the use of a longer distance between sensor and print heads. This distance provides adequate time for calculation and control while reducing exposure to ink mist deposition.
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
The apparatus achieves precise duplex printing with high throughput and maintains high printing quality by using distinct correction data for each surface, reducing slippage and measurement errors, and preventing ink mist deposition on sensors.
Implementation Method 1
A speed sensor 504 (a laser Doppler sensor) that directly measures the moving speed of the sheet
Data Source
AI summary
A control unit includes a memory storing correction data obtained by associating information acquired by a first acquisition unit (rotary encoder) with information acquired by a second acquisition unit (direct sensor) with respect to, at least one rotation of a conveying roller. When a plurality of images are sequentially printed on a first surface and a second surface of a continuous sheet, the control unit reads the correction data corresponding to the rotation information acquired by the first acquisition unit from the memory and corrects at least one of driving control of a print head and driving control of the roller. The correction data used in printing on the first surface of the sheet is different from that used in printing on the second surface of the sheet.