Learn in the textbookDetection Devices (Light, Electromagnetic, and Motion Sensors)
DefinitionAn optical sensor (光学センサー) is a sensor that detects whether light is falling on it and how strong that light is, then converts this into an electrical signal.
ExplanationA sensor is an input-side component that reads a physical quantity such as light, sound, temperature, or movement and turns it into an electrical signal a computer can work with. An optical sensor converts the amount of light reaching its light-receiving surface into a current or voltage level, so it can tell a device whether it is bright or dark, or whether something is blocking the light. When a smartphone brightens or dims its screen to suit the room, for example, the work is done by an ambient light sensor, one type of optical sensor.
AnalogyThink of a lookout posted in a room who notices when the light changes and reports it.