An eye blink sensor works by continuously emitting infrared (IR) waves and detecting their reflection off the eye. When an eye blink occurs, the reflection is interrupted, triggering a change in the sensor's output.
Here's a breakdown of the process:
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Infrared Emission: The sensor contains an IR LED (Light Emitting Diode) that constantly emits infrared light towards the eye. This light is invisible to the human eye.
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Reflection and Detection: The IR light reflects off the surface of the eye and is received by an IR photodiode within the sensor. The amount of reflected light is measured by the sensor's circuitry.
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Blink Detection: When the eye blinks, the eyelid blocks the infrared light from reflecting back to the sensor. This causes a significant decrease in the amount of reflected light received by the photodiode.
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Signal Output: The sensor's internal circuitry detects this change in reflected light. When a blink is detected, the sensor's output signal changes, typically going from a low state to a high state (or vice versa). This output signal indicates that a blink has occurred.
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Data Processing: The signal from the eye blink sensor can then be sent to a microcontroller (like an Arduino) or other processing unit. The microcontroller can then be programmed to perform specific actions based on the detection of blinks. For example, it could trigger an alarm, record the number of blinks, or control a device. The example code given states that the Arduino sends a signal to a buzzer to make noise when a blink is detected.
In summary, an eye blink sensor uses infrared light to detect the presence or absence of reflection from the eye, allowing it to register blinks and provide an electrical signal that can be used for various applications.
