Apple is always trying to develop and deliver the highest quality of displays for their premium devices. Yesterday, the US Patent & Trademark Office published a patent application from Apple that relates to organic light-emitting diode (OLED) displays in which one or more organic photodetectors (e.g., organic photodiodes) are integrated for in-cell optical sensing.

In-cell optical sensing is the sensing of light using optical photodetectors (OPDs) that are integrated with a display. In-cell optical sensing may be used in various applications, such as biometric sensing (e.g., face, fingerprint, or retina sensing), OLED illumination sensing, touch sensing, ambient light sensing, or health sensing. OPDs may be configured to sense visible light, infrared light, or other ranges of electromagnetic radiation wavelengths.

Apple's invention covers systems, devices, methods, and apparatus that are directed to in-cell optical sensing and, more particularly, to the integration of OPDs into an OLED display.

Technically speaking, an OPD pixel, or an array of OPD pixels, may be integrated into an OLED display while forming the display (e.g., in parallel with forming OLED pixels).

Alternatively, the OPD pixel(s) may be integrated into the display after the display is formed (e.g., after the OLED pixels are formed). While the latter may enable the OPD pixel(s) to be optimized largely independently of the OLED pixels, such optimization may at times conflict with optimizing the OLED pixels. Therefore, to preserve the integrity of a display as much as possible, the systems, devices, methods, and apparatus described in Apple's patent application include OPD pixels that are formed while forming an OLED display.

The OPD pixels, as described in the patent filing, may be formed such that they share the cathode, OLED HTL, or OLED ETL structures (e.g., materials and layers) used by OLED pixels. The OPD pixels may also share other structures used by OLED pixels, such as hole injection layer (HIL), hole blocking layer (HBL), electron injection layer (EIL), or electron blocking layer (EBL).

In respect to Apple's patent FIG 1A below, they note that in some cases, the front-facing camera #110, I/O devices #116, and/or other sensors of an iPhone (device #100) may be integrated with a display stack of the display #104 and moved under the display.

For example, an array of OPD pixels may be interspersed with, or positioned around, an array of OLED pixels included in the display. The OPD pixels may be used as a camera (e.g., a visible light camera and/or an infrared camera) capable of acquiring an image of one or more of an environment of the iPhone, an image of a user (e.g., the user's face, finger, or retina).

Apple's patent FIG. 2 below shows an example plan view of a portion of an OLED display #200 that integrates an array of OPD pixels #208.

Apple's patent FIG. 9 shows one example embodiment of an OPD pixel (#900). Apple's patent presents an additional four examples of possible OPD pixel configurations.

As with most patents, Apple never wants to limit the use of an invention to a single device, even though they focus on the device that it will apply to first. In this case, Apple notes that the invention could be used in other form factors including an Mixed Reality Headset, smartglasses, health monitoring device, Apple Watch, vehicle navigation systems, robot navigation systems, an iPad and more.

For more details, review Apple's patent application 20220293682.

Although Apple's latest patent filing is the most sophisticated to date, Apple's engineering teams have been working on cameras under the display for years, covering various approaches for both Touch and Face ID: 01, 02, 03, 04, 05, 06, 07, and more.     

Apple's Inventors

Markus Einzinger: Sr. Electrical Engineer. An experienced researcher with a proven track record of successful OLED device design, optimization and prototyping.

Martijn Kuik: Technical Lead

Moe (Mohammad) Yeke Yazdandoost: Tech Lead – Lead Sensing Systems Architect

Niva Ran: Senior Data Scientist / Senior Optical Display Engineer