ABSTRACT
Remote control of toys or television games with optical sensors is quite common. The signals are typically transmitted using a near-infrared light emitting diode (LED). A near-infrared emitter is pulsed with a high current transmitting a specified pattern of light pulses while the photosensor looks for very small changes in the ambient light level. Many moneychangers operate with an optical sensor principle. Calibrated near-infrared LEDs and UV LEDs with the appropriate photosensor are focused at key points on the bill. A coin changer offers a number of different applications for interruptive-type optical sensors or arrays. The smoke detector efficiency can be greatly increased by changing the photosensor from a 90° reflective to a transmissive configuration. Slot machines have coin sensors as well as credit card sensors and encoders that provide the exact position of the rotating wheels. Interruptive- and reflective-type optical sensors can be used to measure the precise velocity and direction of a golf ball struck by a club.
