"Oppo also became the first smartphone brand to unveil an engineering sample with under-display selfie camera last week, by putting the front facing camera under the AMOLED display, although we believe its peers such as Xiaomi, Lenovo, Apple, Huawei, etc., are also working on similar solution. This technology allows a real full screen design as there is no hole or notch on the display, and the screen can act as a screen when the front camera is not in use. Nevertheless, the display image quality in the area surrounding the camera seems to be worse than the rest of the display as it requires special treatment and processing. Moreover, the native image quality (resolution, contrast, brightness, etc.) taken by the under-display selfie camera is also not comparable with current front facing camera. Our checks suggest the brands (not just Oppo) are currently working with software/AI companies for post-processing."
The report also talks about the efforts to reduce under-display fingerprint sensor thickness:
"All of the flagship Android smartphones showcased at the MWC Shanghai are equipped with under-display fingerprint sensing, mostly adopting optical sensor with only Samsung using ultrasonic sensor, and none of them is using Face ID-like biometric sensing. We believe under-display fingerprint is becoming the mainstream for Android's high-end smartphones and could further proliferate into mid-end as the overall cost comes down. We estimate overall under-display fingerprint shipment of ~200 mn units in 2019E (60 mn units for ultrasonic and 140 mn units for optical), up from ~30 mn units in 2018, and could further increase to 300 mn units in 2020E, excluding the potential adoption by iPhone.
For the optical under-display fingerprint, our checks suggest the industry is working on (1) thinner stacking for 5G; (2) half-screen sensing for OLED panel; (3) single-point sensing for LCD panel; and (4) full-screen in-cell solution for LCD panel. As mentioned earlier, 5G smartphone will consume more battery power and it will be necessary to reduce the thickness of the under-display fingerprint module for more room to house a bigger battery.
Currently, optical under-display fingerprint sensor module has a thickness of nearly 4 mm, as its structure requires certain distance between the CMOS sensor and the AMOLED display to have the best optical imaging performance. Given the overall thickness of the handset nowadays is around 7.5-9.0 mm, smartphone makers are required to sacrifice the battery capacity to make extra room for the optical under-display fingerprint sensor. The new structure for 5G smartphone that Goodix and Egis are working on will be adopting MEMS Pinhole structure, replacing the current 2P/3P optical lens structure, given the MEMS Pinhole design could achieve total thickness of 0.5-0.8 mm, versus ~4 mm for 2P/3P optical lens. Our checks suggest the supply chain is preparing sampling/qualification of the new structure in 2H19 for mass production in 2020."