Sheet Alignment via Optical Mark Detection
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Solution Overview
Problem
Existing sheet-processing machines face challenges in accurately aligning sheets without causing damage to the printed image, particularly during rough alignment and measuring sheet position in motion, which affects machine speed and precision.
Innovation Solution
A device and method that utilize sensors to detect pre-printed side marks on sheets, allowing for precise alignment via grippers, with a two-part measurement process for rapid and precise positioning, enabling high-speed and accurate sheet alignment without side lays or large-area pressing devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If rough alignment is performed using traditional side lays or pressing devices, then sheet positioning is achieved, but the printed image may be damaged
Solution Approach 1:
The patent replaces mechanical side lays and pressing devices with an optical measurement system using sensors to detect sheet position. The gripper system is controlled based on sensor feedback to achieve alignment without mechanical contact that could damage the printed image, substituting mechanical alignment with sensor-based positional control
Solution Approach 2:
The sheet itself provides alignment information through pre-printed side marks that serve as reference features. The sensor detects these marks to determine sheet position, allowing the sheet to self-identify its position without requiring external mechanical alignment devices that could cause damage
2Measurement precision
If traditional measuring devices are used to detect sheet position, then alignment information is obtained, but measurement errors occur due to side edge anomalies
Solution Approach 1:
Instead of directly measuring the physical side edge of the sheet which may have anomalies, the system uses sensors to detect optical images of pre-printed side marks. This creates a reliable digital copy of the sheet's intended position based on manufactured marks rather than potentially defective physical edges
Solution Approach 2:
The patent changes the measurement parameter from detecting the physical side edge position to detecting the position of pre-printed side marks. This parameter change from mechanical edge detection to optical mark detection eliminates sensitivity to edge anomalies while maintaining measurement precision
3Productivity
If high-speed sheet processing is implemented, then productivity increases, but alignment precision decreases
Solution Approach 1:
The sheet is pre-marked with side marks during the printing process, preparing alignment reference features in advance. This preliminary action allows the sensor to quickly detect position without requiring complex real-time analysis, enabling high-speed processing while maintaining precision
Solution Approach 2:
The optical sensor system replaces mechanical measurement devices, enabling non-contact, high-speed detection of sheet position. This substitution allows for rapid data acquisition and processing that maintains alignment precision even at high machine speeds where mechanical systems would be too slow or inaccurate
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 allows for quick and precise alignment of sheets, enhancing machine speed and preventing damage to printed images by separating rough and fine alignment processes, ensuring accurate sheet positioning and processing.
Implementation Method 1
The sensor (31) is assigned to a lateral area of the sheet transport path and is designed for optically detecting the lateral area of a sheet (7, 8, 30). The sensor (31) is arranged in such a way that it detects a position of a mark (32)
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
The invention relates to a sheet processing machine, in particular a sheetfed printing press or sheet die cutting machine, having a sheet infeed, having at least one stop (2) for feeding and aligning sheets (7, 8, 30), and having a device for monitoring sheet travel along a sheet transport path of the sheet infeed, comprising at least one measurement apparatus (10, 17, 29) for detecting a lateral sheet edge (39) of the sheet (7, 8, 30), and to a method for monitoring sheet travel along a sheet transport path in a sheet infeed. The problem to be solved by the invention is that of creating an alternative device and an alternative method for monitoring sheet travel along a transport path of a sheet processing machine. The invention is characterized by at least one sensor (31), which can be associated with the lateral region of the sheet transport path, and which is designed for optical detection and determination of the position of a mark (32) on the sheet (7, 8, 30).