Recent LG Display Patents Describe OLED Technology Sony Calls Acoustic Surface
A string of LG Display patent applications recently published at the Patent and Trademark Office raise questions about Sony claims it developed the Acoustic Surface sound technology featured in its A1 OLED 4K Ultra HD TVs introduced at the last CES using panels sourced from LG Display (see 1702060008).
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Sony stands by its previous claims that Acoustic Surface “is a proprietary Sony technology,” a spokesman told us. “The actuator is a generic principle technology. However, the A1 series is the world's first TV which has applied this technology for a large screen TV. The peripheral patent for this technology is now under patent pending.” LG Display didn’t comment, but the panel maker this year began marketing the inventions disclosed in the patents under the commercial name “Crystal Sound OLED.” LG Display has a “strategic partner” that's using the technology, the panel maker said in January without mentioning Sony by name (see 1701300040).
We found nine filings from LG Display for a sound-generating TV screen, each running dozens of pages and describing in elaborate detail methods and technology that looks very similar to Acoustic Surface, which Sony calls a proprietary system that uses the TV’s OLED panel as the sound source (see 1701310016). All the filings, published at the PTO since late September, originate from the same cluster of South Korean applications made between March and November 2016 by a small team of Korean inventors. The nine applications are 20170280215, 20170280216, 20170280217, 20170280234, 20170280243, 20170280246, 20170280249, 20170287990 and 20170289694.
All the applications describe “panel vibration” as a practical solution to the problems of conventional TV speaker systems that rely on drivers that fire in directions away from the viewer, lessening the “immersive experience” of TV watching. When audio is generated through speakers mounted on the rear or the underside of a TV, the quality also can be degraded when the sounds bounce off walls or the floor, they say. With TV form factors becoming thinner and bezels disappearing, little real estate is left to mount quality speakers on the set, say the applications.
LG Display’s solution is to make the screen act as the speaker by vibrating it with actuators, say the applications. The various filings describe slightly different ways of implementing that, with actuators made to act like speaker voice coils using fixed magnets and movable bobbins of wire. For better stereo, left and right actuators can be spaced across the screen, say some of the applications. For better bandwidth, different actuators can be fashioned to handle high and low frequencies, say the others.
The applications generally are broadly worded to apply to implementations on various types of display panels. But the 20170287990 application, filed in April 2016 and published Oct. 5 at the PTO, appears to be of special importance because it fleshes out a point Sony made at its demonstrations of the A1 Bravia TV, namely that OLED panels work best for direct sound generation because they're thinner and lighter.
The 20170287990 application adds that bottom-emission OLEDs work best for generating sound. “The encapsulation layer in contact with the sound generating actuator may be a metal thin film layer having a thickness of 0.05 to 0.2 mm,” or a tiny fraction of an inch, says the application. By reducing thickness and weight, the bottom-emission OLED panel “allows the sound generating actuator to easily generate the vibration, has an improved sound reproduction performance, and can increase the sound output compared to a top emission type device when using the same actuator,” it says.