Page 108 - Electronic Mechanic - TP - Volume - 2

ELECTRONICS MECHANIC - CITS

Types of touch sensors:-

• Capacitive touch sensors
• Resistive touch sensors
• Surface acoustic wave touch sensors
• Infrared touch sensors

• Optical touch sensors
• Projected capacitive touch sensors
Finger print sensors
Fingerprint sensors are biometric security devices that capture and analyze fingerprint patterns for identification
or authentication purposes.

Phones use one of three different technologies to read your fingerprint: optical, capacitive or ultrasonic. An optical
fingerprint reader is the oldest of the three. It uses a specialized miniature camera to take a picture of your finger,
often backlit with little LEDs or the phone’s screen.
unluckily, these sensors are easy to fool – even a good photo can trick them, so it may be combined with a
capacitive sensor, the second technology, to check there is really a finger there.
A capacitive fingerprint sensor uses a grid of tiny capacitors that store electricity, which is discharged only at
the points where your fingerprint ridges touch. An array of thousands of capacitors can then be used to map the
pattern of your fingerprint. Sometimes these sensors also support swipes or force sensing.
The third and most advanced form of fingerprint sensing uses ultrasonic. Much like the ultrasonic scanners
used for medical purposes, an ultrasonic sound pulse is transmitted to your finger and the reflected pulse is
measured. Bats, whales and dolphins use ultrasonic to understand the shape of their surroundings; the sensors
on a Smartphone use it to understand the 3D shape of the ridges in your fingerprint. It can even work through the
phone screen.
Types of finger print sensors

• Capacitive fingerprint sensors.
• Optical fingerprint sensors.
• Ultrasonic fingerprint sensors.
• Thermal fingerprint sensors.
• RFID fingerprint sensors.
PROCEDURE

1 Preparation
Power off the Smartphone and disconnect it from any power source.Gather the necessary tools and replacement
sensors.

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CITS : E & H - Electronics Mechanic - Exercise 144