Endless Belt Coating Using Reference Marking for Stretch Compensation
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Solution Overview
Problem
Existing printer technologies for printing on endless belts face issues with belt stretching and speed changes during the printing process, leading to incorrect transfer of the print image due to mechanical loads and speed variations.
Innovation Solution
A method and device that utilize a continuous material measure, such as an optical marking, applied to the endless belt to detect lateral movement and speed changes, allowing for real-time correction of belt position and speed, ensuring accurate image transfer. This involves using sensors and actuators to synchronize the belt and printer movements, with the option of applying the scale in a non-positive manner or by altering material properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a digital printer is used to apply mask-shaped coating to an endless belt, then the coating can be applied with design flexibility, but the belt stretching and speed changes during printing cause incorrect transfer of the printed image
Solution Approach 1:
A dimensioning element (scale or reference marking) is applied to the endless belt before the printing process. This preliminary marking serves as a reference that allows the control system to detect and compensate for belt stretching and speed variations during printing, ensuring accurate image transfer despite mechanical disturbances
Solution Approach 2:
A sensor detects the position of the dimensioning element on the moving belt and provides real-time feedback to the control system. The control system uses this feedback information to adjust the printing process dynamically, compensating for belt stretching and speed changes to maintain printing precision
2Productivity
If the endless belt runs between deflection rollers under mechanical stress, then the belt can be conveyed continuously, but the mechanical stress causes belt stretching that distorts the printed image
Solution Approach 1:
The dimensioning element is applied to the belt in advance, creating a permanent reference that moves with the belt through the printing zone. This reference allows the system to measure and compensate for stretching caused by mechanical stress during continuous operation
Solution Approach 2:
The system replaces purely mechanical positioning with an optical/electronic measurement and control system. Sensors detect the dimensioning element position optically, and the control system electronically adjusts printing parameters to compensate for mechanical stretching, substituting mechanical precision requirements with sensor-based feedback control
3Adaptability or versatility
If the speed of the continuous belt changes during printing, then the printing process can adapt to varying production rates, but the speed variations result in incorrect transfer of the printed image
Solution Approach 1:
The printing system transitions from a static, fixed-speed process to a dynamic, adaptive process. The control system continuously monitors belt speed variations through sensor feedback and dynamically adjusts printing parameters in real-time, allowing accurate printing despite speed changes during the printing process
Solution Approach 2:
Real-time speed feedback from the sensor detecting the dimensioning element enables the control system to respond to speed variations. The feedback loop continuously adjusts the printing process to match actual belt speed, maintaining image transfer accuracy across varying production rates
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 solution effectively compensates for belt stretching and speed changes, ensuring precise transfer of the printed image onto the endless belt, maintaining image quality despite mechanical disruptions.
Implementation Method 1
the surface of the continuous strip can be illuminated with a light source. Using the array of photosensitive elements, the intensity distribution of the reflected light can be recorded
Data Source
Figure 1
AI summary
The invention relates to a method and to a device (1) for applying a mask-shaped coating to an endless belt (2), the coating being applied to an outer face of the endless belt (2) in the form of drops by means of a printer (3), characterized by the following steps: a) applying or transferring at least one material measure (6, 7) to the endless belt (2), in particular to a surface of the endless belt (2); b) detecting the position of the material measure (6, 7) and/or a periodic division of the material measure (6, 7) by means of at least one sensor (4, 5); c) generating a signal to print and transmitting said signal to the printer (3) if the position of the material measure (6, 7) on the surface of the endless belt (1) detected by the at least one sensor (4, 5) corresponds to a target position and/or if the at least one sensor (4, 5) detects an end or a beginning of a division period of the material measure (6, 7); d) discharging drops of a coating material onto the outer face of the endless belt (2) by means of the printer (3) after the signal has been received.