STEM与日常科技·英语30篇（7）

21 / 30

免触式洗手液分配器如何准确测量手掌尺寸

Touchless soap dispensers use infrared time-of-flight sensors to estimate hand size before dispensing.
They emit invisible light pulses and calculate distance based on how long light takes to bounce back.
By scanning multiple points across the palm area, they build a rough 3D profile in under half a second.
This prevents over-dispensing for small hands or under-dosing for larger ones.
Algorithms adjust output volume depending on detected surface area and proximity.
Some models even learn user habits after repeated use to refine future responses.
The sensor must distinguish hands from other objects like bags or sleeves using motion context.
Power efficiency matters, so systems activate only when motion enters a defined detection zone.
Calibration occurs during manufacturing and rarely needs field adjustment due to stable optics.
This precision reduces waste and improves hygiene in hospitals and schools alike.