Lithium Battery
Laser Triangulation Measurement of Step Height at Lithium Electrode Splice Joints
An online method for locating short splice joints and measuring either surface step height with one sensor or total thickness change with synchronized opposed sensors.
Background
A splice joint creates a localized height or thickness change in a continuous electrode web. The joint must be located and measured before winding or stacking without contacting the coated foil.
Pain Points
- • A short joint requires position triggering and sufficient spatial sample density.
- • Web runout can be mistaken for splice step height in a single-sensor arrangement.
- • Tape, metal foil, and coating surfaces can produce different return-signal levels.
Measurement Solution
Joint location: Use the splice signal, a mark sensor, or an encoder window to define the inspection region. Determine the sampling rate from line speed and the shortest joint feature that must be resolved.
Single-sensor step measurement: Measure surface height over a stable support and compare the baseline before, within, and after the splice. This arrangement is compact, but the result also contains whole-web motion.
Opposed-sensor thickness measurement: When total joint thickness is required, mount synchronized sensors above and below the web and calibrate their fixed separation. Align both spots to the same cross-section before comparing normal and splice regions.
Model selection: ST-P25, ST-P30, and ST-P50 are candidates for short working distances and small step changes. Confirm range, repeatability, spot size, and mounting clearance from the specifications below.
Surface verification: Test actual tape, foil, and coating combinations. Check the valid-data ratio through both transition edges, then adjust angle, exposure, or filtering only from the sample result.
Decision and integration: Establish separate statistics for the normal web and splice region. Apply limits from the process specification, and retain the raw waveform when sending results to a PLC or host system through Ethernet, RS485, or analog output.
| Model | Reference Distance | Measuring Range | Repeatability | Linearity Error |
|---|---|---|---|---|
| ST-P25 | 25 mm | ±1 mm | 0.05 μm | <±0.6 μm |
| ST-P30 | 30 mm | ±5 mm | 0.15 μm | <±3 μm |
| ST-P50 | 50 mm | ±10 mm | 0.25 μm | <±4 μm |
Technical Advantages
- • Encoder or splice-trigger synchronization improves short-joint localization.
- • Single- and opposed-sensor arrangements address surface step and thickness change respectively.
- • Stored joint waveforms support threshold review and quality traceability.