Yes, the smartphone recently reached popular YouTuber JerryRigEverything’s lab for test and got a teardown, revealing how the innards look like. And the fourth sensor is right where the in-display fingerprint sensor is (see video below).
He starts by removing the custom transparent glass back on his OnePlus 6T unit (
review) and removes the exposed screw just above the battery. He says that removing the battery was pretty easy and so was the motherboard. One can simply remove the eight screws holding the NFC and the plastic covering the motherboard and the front/rear camera tech.
Further, he removes all the seven screws below the battery that encloses the in-display fingerprint scanner, speaker and the USB Type-C port under a plastic shell. He pulls off the shielding tape on top of the fingerprint sensor and removes two black screws holding the sensor in place.
Pulling out the in-display fingerprint sensor reveals the fourth ‘hidden’ camera sensor.
You heard it right, there’s a camera sensor placed right under the screen as a part of the in-display scanner tech. Although the exact purpose is not yet known, it is being assumed that the camera makes the sensor performance more accurate than others. In the video, the camera is seen attached to the sensor that reads your fingerprint when the green light animation on the screen illuminates the fingerprint.
It is placed close to the AMOLED display as one can see the underside of the screen once the camera sensor is removed.
Although OnePlus is using this tech for the in-display fingerprint sensor, the YouTuber says that in future it could be used for selfie cameras as well. This means getting rid of the notch altogether.