Redmi, a sub-brand of Chinese tech company Xiaomi, has recently shown off a working in-display fingerprint sensor on a Liquid-Crystal Display (LCD) panel, potentially paving the way for the tech to be implemented in lower-cost smartphones.
In-display fingerprint sensors have been increasing in popularity in recent months, with many of the world’s major tech companies either filing patents on the technology, or including them in some of their latest offerings.
However, because of the need for the sensors — placed under the glass panel of the screen — to scan the image of the fingerprint in order to get a reading, they have been limited to use with Organic Light-Emitting Diode (OLED) panels.
OLED panels allow for each individual pixel in a display to switch on or off, allowing for light to pass through from a fingerprint sensor (when placed beneath the panel) to the fingerprint.
By comparison, LCD panels are backlit, with all pixels in the display either switched on or off. This makes the passage of light sensors through the display more challenging, and until recently, unviable for in-display fingerprint technology.
Redmi’s solution to this problem involves using infrared light positioned in the lower portion of the display to read the user’s fingerprint.
“The innovative use of infrared high-transmittance film material greatly improves the transmittance of infrared light that could not pass through the screen,” said Redmi executive Lu Weibing in a post on Weibo, via Android Authority. “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,” he added.
LCD displays are primarily used in lower-cost smartphones, and this potential breakthrough could see the implementation of the popular form of biometric authentication make its way to more affordable devices as a result.
Biometric authentication company Goodix has also previously stated its intention to bring this technology to LCD screens, and this announcement by Redmi could further spur the company toward that goal.
There is no indication, however, of how well this solution works, and Redmi has yet to announce any plans to include in-display sensors in any of their upcoming 2020 smartphone offerings.