Apple always tries to develop and deliver the highest quality displays for its high-end devices. Yesterday, the United States Patent and Trademark Office published a patent application from Apple relating to organic light-emitting diode (OLED) displays in which one or more organic photodetectors (eg, organic photodiodes) are integrated for optical detection in the cell.
Optical sensing in the cell is the detection of light using optical photodetectors (OPDs) which are integrated into a screen. Intracellular optical sensing can be used in various applications, such as biometric sensing (e.g., face, fingerprint, or retina sensing), OLED illumination sensing, touch sensing, light sensing ambient or health sensing. OPDs can be configured to detect visible light, infrared light, or other wavelength ranges of electromagnetic radiation.
Apple’s invention covers systems, devices, methods and apparatus for optical detection in the cell and, more particularly, to the integration of OPD in an OLED screen.
Technically speaking, an OPD pixel, or an array of OPD pixels, can be integrated into an OLED display while forming the display (eg, in parallel with forming OLED pixels).
Alternatively, the OPD pixel(s) may be integrated into the display after the display has been formed (eg, after the OLED pixels have been formed). While the latter may allow the OPD pixel(s) to be optimized largely independently of the OLED pixels, such optimization may sometimes conflict with OLED pixel optimization. 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 when forming an OLED display.
OPD pixels, as described in the patent filing, can be formed such that they share the cathode, OLED HTL, or OLED ETL structures (eg, materials and layers) used by OLED pixels. OPD pixels can also share other structures used by OLED pixels, such as hole injection layer (HIL), hole blocking layer (HBL), electron injection layer (EIL) or the electron blocking layer (EBL).
Regarding Apple’s patent FIG 1A below, they note that in some cases, front camera #110, I/O devices #116 and/or other sensors of an iPhone (device #100) can be integrated into a display stack of display #104 and moved under the display.
For example, an array of OPD pixels can be interspersed with, or positioned around, an array of OLED pixels included in the display. OPD pixels can be used as a camera (for example, 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 (for example, the user’s face, finger or retina).
Apple’s patent FIG. 2 below shows an example plan view of part of a #200 OLED display that incorporates an OPD #208 pixel array.
Apple’s patent FIG. 9 shows an embodiment of an OPD pixel (#900). Apple’s patent presents four additional 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 if they focus on the device to which it will first apply. In this case, Apple notes that the invention could be used in other form factors, including mixed reality headset, smart glasses, health monitoring device, Apple Watch, vehicle navigation systems , navigation systems for robots, an iPad, etc.
For details, see Apple patent application 20220293682.
Markus Einzinger: Senior Electrical Engineer. An experienced researcher with a proven track record in successfully designing, optimizing and prototyping OLED devices.
Martin Kuik: technical Manager
Moe (Mohammad) Yeke Yazdandoost: Technical Manager – Principal Architect of Detection Systems
Niva Ran: Senior Data Scientist / Senior Optical Display Engineer