According to a recent report by Patently Apple, Apple has applied for a patent application in Europe with references to an original US filing made before, titled, "Display with Embedded Pixel Driver Chips". The new patent publication relates to Apple’s approach towards high resolution display panels and the technicalities of replacing TFT substrates in a display with a matrix of micro-LEDs on the microcontroller substrate.
Two out of the five inventors were previously with LuxVue, a micro-LED company acquired by Apple in May 2014. One of the inventors is former Vice President of LuxVu Sandy (Hsin-Hua) Hu who is now working at Apple as micro-LED, MEMS, III-V & Silicon integration pioneer.
In general, Apple notes that conventional organic light emitting diode (OLED) or liquid crystal display (LCD) technologies feature a thin film transistor (TFT) substrate. More recently, it has been proposed to replace the TFT substrate with a matrix of microcontrollers bonded to the substrate and build a micro light emitting diode (LEDs) display by integrating a matrix of micro LEDs on the microcontroller substrate, in which each microcontroller is to switch and drive one or more micro LEDs.
Apple's invention covers a display integration scheme in which pixel driver chips are embedded face up in a display substrate. A front side redistribution layer (RDL) is formed over the pixel driver chips and insulator layer forming the display substrate, and the LEDs are placed on the front side RDL layer. This integration scheme may allow for significant freedom in designing and locating the pixel driver chips, which can be virtually any size. Conductive pillars can be formed through the insulating layer for connecting to chips that can be placed on a back side of the display substrate (e.g., power management IC, timing controller, processor, memory, etc.).
It's the first patent with a reference to micro-LED displays being used in connection with a foldable smartphone or other device.
Apple notes that the patent as illustrated (see figure A), is an isometric view illustration of a foldable display panel (#100) in accordance with an embodiment. Figure B is a side view illustration of a curved or flexible display; and Figure C is a top view illustration of a plurality of display panel tiles (#100) arranged side-by-side. In such a configuration, the tiles may be used together to form a larger screen or display area. It should be noted that the illustration of a folding device is not part of a design patent but rather a utility patent which means it's only a generic figure illustrating a folding device which of course could end up being larger, wider, used as foldable iPhone, iPad or future foldable notebook.
Apple's patent application that was published in Europe showed a history back to U.S. patent application 20190096864 published in late May, 2019. For engineers wishing to dive further into the heart of the patent covering "Display with Embedded Pixel Driver Chips," click here.