Under-Display sensors

During Displayweek 2024, Visionox demonstrated many OLED display technologies and panels, and also an interesting microLED prototypes (produced by its subsidiarity Vistar).

Visionox is in the final stages of development of its ViP maskless display production process, and the company showcased some nice ViP smartphone panel prototypes (the technology can be used for any panel size). ViP offers a high improvement in aperture ratio (69% up from 29%) which results in low power consumption and brightness (up to 4X according to Visionox), improved lifetime (up to 6X), improved PPI and more.

TCL CSOT demonstrated its latest displays, technologies and prototypes at Display Week 2024. The company is focused on inkjet printing technologies, and a lot of the displays on show were indeed printed.

So first up, we TCL demonstrated a 14" 2880x1800 400 nits 30-120Hz ink-jet printed LTPO AMOLED display. The display is produced on a glass substrate, with thin film encapsulation (a 'hybrid OLED').

During a trade show, Samsung Display discussed its zero-border, or full-screen OLED technology. Samsung is developing several technologies to enable this kind of display - including 3D bonding, edge brightness control, and an under-the-display camera (Samsung calls its UPC, under-panel-camera). 

Placing the camera under the OLED is a critical part of this solution, and Samsung said that it is developing the technology to enable this - including an increase of 50% in the light transmission of its OLED displays and a new sub-pixel structure that improves the display quality.

Samsung Display demonstrated many OLED technologies at Display Week 2023, which we'll detail below. It seems that the main new technology was the Sensor OLED Display, which is an OLED with an embedded sensor that can perform fingerprint sensing in addition to blood pressure, heart rate sensing and stress level sensing (all from reading the finger), which the company says is the first such display in the world.

The Sensor OLED Display embeds light-sensing organic photodiodes (OPDs) inside the display itself, which allows it to perform the sensing functions all over the display. Samsung explains that as OLED light is reflected differently depending on the contraction and relaxation of the blood vessels inside the finger, the OPD senses the light when it returns to the panel, and converts it into health information.

Researchers from Carnegie Mellon University's Future Interfaces Group (FIG) designed a new haptic screen technology, which they call Flat Panel Haptics, that uses embedded electroosmotic pumps (EEOPs) that can move liquids quickly using electrical fields. 

The whole haptic layer is thin (just 1.5 mm thick) and can be placed behind a flexible OLED display to create an useful haptic display, as can be seen in the video above - buttons or keys can pop-up from the screen, and the interface can take advantage of shaped icons (like a play button or a stop button). Currently the shapes are pre-defined and cannot be altered by the user, but in the future this may change if the FPH technology is used to create small dot-matrix items.

The following is a sponsored post by ISORG

ISORG is a French company based in Grenoble and Limoges in France, and the world centre of excellence for OPD technology (Organic Photo Diode). With more than 85 patents, ISORG is a technology rich company focused on three main market opportunities: (i) Smartphone fingerprint sensing, (ii) Security applications such as identification and border-crossing markets and (iii) SWIR and NIR CMOS imaging markets for automotive, AR-VR and smartphone applications. It has Gen 2 and Gen 3.5 factory capacity in France and a set of partnerships with leading companies in sensing and authentication. More can be found on ISORG here. In May 2022, CEO Dieter May left the helm of OSRAM Opto Semiconductors to join ISORG.

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Display industry consultant Ian Hendy has interviewed ISORG's CEO Dieter May.

BOE demonstrated its latest OLED technologies and displays at SID Displayweek 2022. The most interesting display is a 95-inch 8K HDR OLED display, produced on an Oxide-TFT panel with a white-OLED CF structure. The panel was produced using an evaporation method.

This is the first time we hear of BOE's evaporation TV program, since around 2016. The company has an active inkjet printing OLED TV project, and in December 2019 it unveiled a 55" 8K (160 PPI) printed OLED TV prototype.

In 2021 we reported that Germany-based trinamiX (a subsidiary of BASF) developed an under-the-OLED 3D imaging sensor, that enables high performance face authentication while working behind the display.

The company now announced that its Face Authentication technology has been accredited according to the top standards as defined by Android and FIDO Alliance, which means that its solution now meets high security demands.

Samsung Display announced its latest OLED panel, the Eco²OLED, which increase light output by 33% compared to SDC's previous OLED panels. The increase light translates into a power consumption reduction of up to 25%.

For the Eco²OLED panel, Samsung finally managed to commercialize a polarizer-free OLED, after many years of R&D. The first phone to adopt this display will be Samsung's upcoming Galaxy Fold 3. Interestingly Samsung says that the new design also enabled it to incorporate a high-quality under-the-display camera as more light is entered through the OLED.

Samsung announced several new OLED devices, including its two new foldable smartphones. First up is the Galaxy Z Fold3, which features a 7.6-inch 1768x2208 120Hz 1200 nits foldable Dynamic AMOLED X2 display, and a 6.2-inch 120Hz 832x2268 external AMOLED display. The foldable phone sports Samsung's first under-the-display selfie camera.

Samsung says that the new Galaxy Fold has an improved hinge design and is more durable compared to previous generation devices. The second phone is the Galaxy Flip3, which features a 6.7-inch 120Hz 1200 nits 1080x2640 foldable Dynamic AMOLED display, and an external 1.9" 260x512 Super AMOLED display.