Rotating Surface Elevation Measurement Using Light Curtain Imaging
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Solution Overview
Problem
Existing systems for measuring elevations on rotating bodies such as flexographic printing plates are not capable of doing so quickly and with high accuracy, often leading to damage and suboptimal print quality due to variations in size, thickness, and mounting issues.
Innovation Solution
A non-contact measurement device using an area scan camera with a light curtain and a reference object, such as a taut wire, to capture surface elevations without physical contact, allowing for precise and rapid measurement of flexographic printing plates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contactless measurement using area scan camera with light curtain is used, then measurement speed and accuracy are improved, but device complexity increases
Solution Approach 1:
The patent replaces mechanical contact measurement systems with an optical measurement system using an area scan camera and light curtain. This substitution eliminates physical contact with the printing plate while achieving high measurement precision through optical detection of surface elevations and depressions.
Solution Approach 2:
The patent introduces a light curtain as an intermediary between the measurement system and the printing plate. The light curtain serves as a reference plane that interacts with the plate surface elevations to create measurable shadow patterns, enabling indirect measurement without physical contact.
2Productivity
If conventional measurement systems are used, then device complexity is reduced, but measurement speed and accuracy deteriorate
Solution Approach 1:
The patent replaces slow mechanical scanning measurement systems with a high-speed optical area scan camera system. This enables rapid capture of the entire printing plate surface in real-time during rotation, dramatically increasing measurement speed while maintaining accuracy through optical detection.
3Reliability
If contact measurement methods are used, then device complexity is reduced, but damage to printing plates occurs
Solution Approach 1:
The patent replaces mechanical contact measurement with optical measurement using an area scan camera and light curtain. This eliminates physical contact forces that could damage the printing plate surface, particularly important for fine print dots and delicate plate materials, while maintaining measurement reliability.
4Loss of time
If manual measurement and adjustment procedures are used, then device complexity is reduced, but downtime increases
Solution Approach 1:
The patent performs measurement of the printing plate surface elevations and depressions in advance during plate mounting or before printing operations. This preliminary measurement enables pre-calculation of register settings and pressure adjustments, eliminating time-consuming manual adjustments during setup and reducing overall downtime.
Solution Approach 2:
The patent implements an automated feedback system where measurement data from the area scan camera is processed by a control unit to automatically calculate optimal register settings and pressure adjustments. This closed-loop feedback eliminates manual measurement and adjustment steps, significantly reducing setup downtime while increasing device complexity through automation.
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
Enables automatic presetting of optimal working pressure and reduces downtime by ensuring uniform print images, minimizing waste, and allowing for dynamic adjustments based on production speed.
Implementation Method 1
the contour of the rotating body creates a shadow in the emitted light
Implementation Method 2
the area camera receives the emitted light without the shadowing by the contour
Data Source
Figure 1
Figure 2a~2c
Figure 2b
AI summary
A device according to the invention for measuring elevations (13) of the surface (14) of a rotating body (6) designed as a cylinder (15), roller (15), sleeve (3) or plate (5) of a printing machine (8), e.g. a flexographic printing plate, with a first motor (7) for rotating the rotating body (6) about an axis of rotation (22) and with a measuring device (18), is characterized in that the measuring device (18) for non-contact measurement comprises at least one radiation source (19) and at least one area camera (21), that the radiation source (19) generates a light curtain (23) as emitted light (23), that a shadow (24) is generated by the contour of the rotating body (6), and that the area camera (21) receives the emitted light (23) without the shadow (24) by the contour. Preferably, the measuring device (18) for non-contact measurement further comprises a reference object (30), e.g.The device includes a wire stretched parallel to the axis, a second motor (29), and optionally a further second motor (29b) for adjusting the measuring device (18) and/or the reference object perpendicular to the axis of rotation (22). This enables the rapid and highly accurate measurement of protrusions, e.g., flexographic pressure points.