Under display fingerprint sensor working
There was a time, when having a lock pin in your Nokia 1100 made you a extremely secretive person. Technology grew from pin to pattern to Fingerprint Scanner to Face-unlock to Under display fingerprint sensor. As the world is getting more digitized, the need of security is increasing day by day. Data breaches are something extremely important to worry about. But how much secure are fingerprint sensors. Under display fingerprint sensor or capacitive fingerprint sensor? Is the former better than the later? Lets start with, what are the types of fingerprint sensors we have
- Optical Fingerprint scanners – Under display sensor
- Capacitive Fingerprint scanners- physical scanner
- Ultrasonic Fingerprint scanners – under display sensor
As we thought that Face-unlock is the praise worthy innovation. We were thinking that it could get better, we have a brand new innovation which is over taking the mobile world by storm and that is, Under display fingerprint sensor. Vivo X21 was the first to introduce under display fingerprint sensor commercially.
Under Display finger print sensors have been in news for so long now. After all the patent registrations and tests Vivo collaborated with Qualcomm to bring First phone with under display fingerprint sensor.
Iphone was the rumored to come with under display fingerprint sensor but a more secure and innovative Face ID was what they actually opted for. FaceID is no doubt extremely secure but yeah expensive too. Since iphone 5s capacitive fingerprint sensor are pretty popular and are used even till now. Under display fingerprint sensor technology is a costly affair, hence not available for mid range smartphones. Even most of the flagship phones like Samsung galaxy s9 , samsung galaxy note 9 don’t have under display fingerprint sensor. The basic question now arrives is, how do they really work?
How do under display fingerprint sensor work?
An under display fingerprint sensor uses and optical Fingerprint sensor to get the fingerprint data. The optical sensor is located under the phone’s screen and hence it is called under display fingerprint sensor. The phones using under display fingerprint sensor use Synaptics Clear ID sensor for high resolution Fingerprint scanning. The chip is only supported for OLED and AMOLED displays.
It works by capturing the reflected light from your finger through OLED or AMOLED pixels. As you touch the phone’s screen on the part under which fingerprint sensor is, the displays lights up to illuminate the fingerprint. The sensor then captures a high resolution scan of the fingerprint with the help of the light reflected from the gaps between the pixels.
The fingerprint data needs to be accurate and hence we need to press the screen slightly hard. This is done so that the sensor is able to differentiate between the ridges, the valleys and the curves of your fingers.
The under display fingerprint sensor will only work with OLED and AMOLED displays. The reason for this is OLED and AMOLED panels don’t use any back-light unlike LCD panels.
Optical Sensors Vs Ultra-Sonic Sensors
The under display scanners we’ve seen so far are optical scanners. These use some light to illuminate your finger. A tiny camera under the screen takes an image of your finger which is then compared to the stored image.
May be in Early 2019 with the launch of Samsung galaxy s10 the under display fingerprint Sensors will be ultrasonic instead of optical. These more expensive units work using ultrasound to build up an image of your fingerprint and work better with contaminated fingerprints – if they’re wet or oily with sun cream, for example. They’re essentially ‘Face ID for your finger’.
The road to ultrasonic fingerprint readers has been reasonably long. In 2013 Qualcomm acquired a company called Ultra-Scan, a small company with “very good IP for ultrasonic waveform” and with a background in producing ultrasonic readers for the US Government.
“We took that and found a way to manufacture in the millions to keep the costs down,” explained Qualcomm’s Alex Katouzian at its recent tech summit. “We don’t need to shine a light source through the display. The light source over time can degrade the LCD…it’s very similar to a photocopier.
Current ultrasonics can penetrate through glass (up to 800 µm or microns thick) and metal (up to 400 µm). We expect Qualcomm’s new sensor to be able to work through thicker materials and generate a 3D pattern of the fingerprint too.
Qualcomm certainly isn’t the only name in fingerprint sensors though; Synaptics is another and their tech is behind Xiaomi’s fingerprint sensor in the Mi 8 Pro (called Clear ID by Synaptics) as well as the previously-mentioned Vivo handset.