Lithium Battery
Laser Triangulation Sensor for Lithium Electrode Edge Warpage and Waviness Inspection
A practical method for non-contact inspection of lithium electrode edge warpage and waviness using stable references, multiple measurement points, encoder synchronization, and clearly defined evaluation rules.
Background
Electrode edges may warp or form periodic waves during coating, calendering, and slitting. A laser triangulation sensor can record a continuous height profile, but the system must distinguish local deformation from whole-web motion.
Pain Points
- • Whole-web vibration is superimposed on local edge deformation.
- • Copper foil, aluminum foil, and coated areas may produce different return-signal levels.
- • Waviness must be evaluated in the spatial domain using line speed or encoder position.
Measurement Solution
Measurement principle: Install one or more ST-P laser triangulation sensors above the electrode edge and measure height relative to a stable reference. A fixed point is suitable for trend monitoring; multiple lateral points or a scanning axis are required when the cross-web profile must also be evaluated.
Reference compensation: If whole-web vibration is significant, add a reference point near the center of the web or measure a stable machine datum. Subtracting the reference channel helps separate local edge warpage from common motion.
Model selection: Select the reference distance and range from the available installation space and maximum expected displacement. ST-P30, ST-P50, ST-P80, and ST-P150 specifications are listed below. Repeatability and spot size must be considered together with range.
Sampling and evaluation: Synchronize samples to encoder position so the time series becomes a spatial profile. Define warpage from a confirmed datum, and calculate waviness only after documenting the filter band, amplitude metric, and wavelength range. Acceptance limits must come from the product drawing or process specification.
Surface and installation checks: Use a rigid bracket and keep the spot away from burrs, holes, and the unsupported edge. Validate signal quality on actual foil and coated samples before adjusting the angle or measurement settings.
Integration and validation: Ethernet is suitable for continuous profile data, while RS485 or analog output can carry status or control values. Verify static repeatability, dynamic correlation, and edge-position tolerance before using the result for alarms or process feedback.
| Model | Reference Distance | Measuring Range | Repeatability | Linearity Error |
|---|---|---|---|---|
| ST-P30 | 30 mm | ±5 mm | 0.15 μm | <±3 μm |
| ST-P50 | 50 mm | ±10 mm | 0.25 μm | <±4 μm |
| ST-P80 | 80 mm | ±15 mm | 0.5 μm | <±6 μm |
| ST-P150 | 150 mm | ±40 mm | 1.2 μm | <±16 μm |
Technical Advantages
- • Continuous non-contact acquisition produces a height profile along the moving web.
- • Reference compensation and multiple points help separate local warpage from common motion.
- • Encoder and control-system integration supports traceable inspection results.