Flat Material Length Measurement Slippage Control
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Solution Overview
Problem
Existing systems for measuring the length of flat products in franking systems face issues with slippage errors, particularly when using encoder signals to determine the length of mail items, which can lead to inaccurate measurements, especially with thick or angular postal items.
Innovation Solution
A method involving a control unit with encoder pulse counters and sensors at multiple stations, where the difference in encoder pulse counts between sensors detecting the leading and trailing edges of flat products is used to calculate the length, ensuring minimal slippage by using the encoder of the transport drive, and incorporating light barriers to detect edge events, with path control instead of time control, allowing for accurate length measurement across various formats.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If encoder signals are used to determine the length of mail items, then length measurement is achieved, but slippage errors occur leading to inaccurate measurements
Solution Approach 1:
A light barrier is introduced as an intermediary detection device between the mail item and the measurement system. The light barrier detects the leading and trailing edges of the mail item by interrupting a light beam, providing accurate positional references without physical contact that could cause slippage. This intermediary sensor system resolves the contradiction by enabling reliable length measurement through optical detection rather than direct mechanical encoding.
2Measurement precision
If a separate encoder and light barrier are used for length determination, then measurement capability is improved, but device complexity increases
Solution Approach 1:
The control unit is designed to integrate multiple functions: it controls the transport drive, counts encoder pulses from the transport roller, and processes light barrier signals for edge detection. By merging these control functions into a single control unit, the system achieves improved measurement capability while minimizing the increase in device complexity through functional integration rather than adding separate independent systems.
3Reliability
If encoder pulses of the transport drive are used for length measurement, then slippage is minimized, but the system requires path control instead of time control
Solution Approach 1:
The system uses feedback from the encoder pulses to continuously monitor the actual position of the transport drive. The control unit compares the encoder pulse count with the expected position based on light barrier detections, and adjusts the transport drive accordingly to maintain accurate path control. This feedback mechanism enables reliable length measurement by minimizing slippage while managing control complexity through intelligent position correction rather than simple time-based control.
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 provides reliable and cost-effective length measurement with minimal slippage, enabling accurate postage calculations for all common letter formats, ensuring timely and precise measurements before printing in franking machines.
Implementation Method 1
a first sensor of the second station for detecting an event... A third sensor S3 detects the leading and trailing edges of a transported flat item during transport
Data Source
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Figure 3
Figure 4~6
AI summary
Method and arrangement for measuring the length of a flat material in a material processing system, comprising a first station (1) and a second station (2), wherein the second station (2) is arranged downstream of the first station in the transport direction of the flat material. Sensors belonging to different stations (1, 2) are used for length measurement. The control unit is programmed to perform position control and is designed to count the encoder pulses of an encoder (13) of the first station. An event is detected by a first sensor (DW-S1) of the second station (2), and a corresponding numerical value Z1 from an encoder pulse counter (14) is stored in a first register (R1) of the control unit of the first station. A numerical value Z2 for a distance d between two sensors (AZ-S3, DW-S1) is stored in a second register (R2) of the control unit (10) of the first station (1).Another event is detected by the sensor (AZ-S3) of the first station, and a corresponding numerical value Z3 from the encoder pulse counter 14 is stored in a third register (R3) of the control unit (10) of the first station (1). As soon as both events are present, the numerical value Z2 and the difference Δ = Z3 - Z1 of the counter values Z3 and Z1 are summed by the control unit (10) of the first station.