Under-display fingerprint scanners are all the rage these days, and every brand’s trying to implement it. Honestly speaking, it’s one of the smartphone trends of 2020. You’ll see most flagships and even mid-rangers flaunt under-display fingerprint sensors. With the tech getting more widely produced and adopted, we’ll even see it packed in low-end and budget phones, but there’s some time for that to happen.
You might have seen that phones like the latest Samsung, Xiaomi, and OnePlus flagship phones flaunting under-display sensors, but all these devices also have OLED display panels. What you might not have seen is a device with an LCD panel that also houses an under-display fingerprint sensor.
The reason? Well, on OLED phones, individual pixels light up to make it easier for the sensors to read a fingerprint, and it’s easier for the optical sensors to “peek” through OLED panels, as they’re thinner. The presence of an under-lying backlighting layer in LCD phones makes it impossible for optical (or ultrasound) sensors to penetrate LCD panels to scan fingerprints.
However, Redmi’s general manager Lu Weibing has teased a phone with an LCD display and a working fingerprint-sensor that sits under the display. The Redmi R&D team has been able to make use of infrared instead of optics or ultrasonic waves to achieve this breakthrough. He also goes on to explain the tech too (machine translated from Chinese):
The innovative use of infrared high-transmittance film material greatly improves the transmittance of infrared light that could not pass through the screen. The infrared transmitter at the bottom of the screen emits infrared light. After the fingerprint is reflected, it penetrates the screen and shines on the fingerprint sensor to complete the fingerprint verification, which solves the LCD-Fingerprint problem.– Lu Weibing, General Manager, Redmi (on Weibo)
Hopefully, this solution is on par with the traditional optical and ultrasound sensors in terms of accuracy and speed. Biometric authentication companies like Goodix had confirmed plans to make the under-display fingerprint sensors work under LCD displays in 2020, and with Redmi achieving this feat, we could see these under-display sensors ship inside budget phones soon.
There has not been any official event or announcement from Xiaomi or Redmi that hints at a particular phone with this tech, but having learned that they have a fully-working solution, we could very well see phones shipping with the tech by this year, at least from Redmi.
You can see Lu Weibing’s Weibo post and the demo video he uploaded here.