Image Forming Apparatus Thermal Head Stretch Compensation
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Solution Overview
Problem
Color deviation occurs in image forming apparatuses due to physical stretching of the transfer medium when heated, leading to deteriorated printing quality, especially in indirect and direct printing methods on thermally stretchable media like tubes and films.
Innovation Solution
An image forming apparatus that includes a thermal head for heating, a conveying device for medium movement, and a detecting device to monitor medium stretch, with a control system that adjusts the image forming unit's operation to correct for stretch-induced deviations by adjusting the thermal head's position and image length in the sub-scanning direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the thermal head heats the transfer medium to form images, then image forming capability is improved, but the transfer medium stretches physically causing color deviation
Solution Approach 1:
The patent applies preliminary action by detecting the stretch of the transfer medium before image formation occurs. The stretch detection unit measures the medium's dimensions prior to heating, and the control unit uses this information to pre-correct image data, adjusting the positioning of subsequent images to compensate for the anticipated stretch. This prevents color deviation by preparing correction data in advance rather than attempting to fix it after the fact.
Solution Approach 2:
The patent implements feedback by creating a closed-loop control system where the stretch detection unit continuously monitors the transfer medium's dimensions during the heating process. The control unit receives real-time stretch information and dynamically adjusts image positioning data accordingly. This feedback mechanism ensures that color deviation is corrected based on actual medium behavior rather than relying on predetermined correction values.
2Manufacturing precision
If the transfer medium is heated in a wide range for high gradation images, then image quality is improved, but physical stretch increases causing greater color deviation
Solution Approach 1:
The patent applies preliminary action by detecting and correcting stretch before it affects image quality. By measuring medium dimensions prior to wide-range heating and pre-calculating correction values, the system prepares compensation data in advance. This allows high-gradation images to be formed without color deviation while avoiding the need for repeated heating cycles or adjustments that would extend printing time.
Solution Approach 2:
The patent implements feedback by continuously monitoring medium stretch during wide-range heating operations. The control unit receives real-time stretch data and dynamically adjusts image positioning to maintain quality across the entire heated area. This real-time correction eliminates the need for multiple heating passes or manual recalibration, thereby preserving productivity while achieving high image quality.
3Manufacturing precision
If color deviation correction is performed by reprinting patterns on the transfer medium, then color deviation is reduced, but correcting time increases
Solution Approach 1:
The patent replaces the mechanical approach of physically reprinting correction patterns on the transfer medium with a data processing approach. Instead of adding physical marks and re-printing images, the stretch detection unit measures actual medium dimensions and the control unit calculates digital correction values that are applied to image data. This substitution eliminates the time-consuming physical correction process while achieving the same color positioning accuracy.
Solution Approach 2:
The patent uses copying by creating a digital representation of the stretch condition through detection data, then applying this information to correct image positioning without physical intervention. The correction is achieved by copying the stretch measurement information into the control system's correction algorithms, which then adjust image data accordingly. This virtual copying approach is far faster than physical re-printing methods.
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 solution effectively suppresses color deviation caused by medium stretching during heating, maintaining image quality and reducing printing time by dynamically adjusting the thermal head's operation based on detected stretch.
Implementation Method 1
a transfer medium is physically stretched owing to heating of the heating element
Data Source
AI summary
In order to provide an image forming apparatus which can reduce color deviation at the time of forming an image on a medium, the present printing apparatus comprises an image forming unit which forms an image by superimposing images, each formed with corresponding color of ink, on a transfer film while heating a thermal head, a film conveying device which conveys a transfer film, a sensor which detects a stretch of the transfer film occurring due to heating with the thermal head, a controller which controls the image forming unit to change a line cycle of the thermal head in accordance with a stretch of the transfer film detected by the sensor.