These extremely small speakers, expected to be the thinnest in the world and less than half the weight of conventional speakers, enable wearable tech such as earphones, over-the-ear headphones, or Augmented-Reality/Virtual-Reality (AR/VR) headgear to become even more compact and comfortable. Their extremely low power consumption saves extra weight and size by allowing smaller batteries, and unlike conventional speakers they generate negligible heat.
As MEMS (Micro Electro-Mechanical Systems) devices, the speakers are leveraging technology that has already revolutionized the capabilities of smartphones and wearables. High-performing MEMS motion sensors, pressure sensors, and microphones built on silicon chips are the critical enablers for context sensing, navigation, tracking, and other features that mobile users now rely on every day. With MEMS advancements now coming to speakers, designers can further miniaturize the audio subsystem, reduce power consumption, and create innovative features like 3D sound.
“This successful project combines USound's design flair and ST's extensive investment in MEMS expertise and processes, including our advanced thin-film piezo technology PeTra (Piezo-electric Transducer)," says Anton Hofmeister, Vice President and GM of MEMS Microactuators Division, STMicroelectronics. "Together, we are winning the race to commercialize MEMS micro-speakers by delivering a more highly miniaturized, efficient, and better-performing solution leveraging the advantages of piezo-actuation."
“ST has provided the production expertise and manufacturing muscle to realize our original concept as a pace-setting, advanced product ready for consumer-market opportunities," says Ferruccio Bottoni, CEO of USound. “These tiny speakers are now poised to change the design of audio and hearable products, and open up new opportunities to develop creative audio functionalities."
In addition to applications in mobiles, audio accessories, and wearables, the new piezo-actuated silicon speakers will support innovation in a wide variety of hearable electronics, including home digital assistants, media players, and IoT (Internet-of-Things) devices.
During CES 2018, USound will demonstrate prototype AR/VR glasses containing multiple MEMS speakers per side. The demo will leverage the speakers' ultra-thin form factor, low weight, and high sound quality to show how miniaturized audio systems can deliver outstanding experiences, and advanced features such as beam forming for private audio, within the extremely tight size, weight, and power constraints imposed by glasses and other wearables.
The advanced MEMS micro-speakers feature a piezo-electric actuator that deflects in response to analog audio signals. Taking advantage of this phenomenon presents an alternative to the conventional electro-mechanical speaker; the MEMS micro-speakers are fabricated completely on silicon and therefore simpler, more reliable, and more economical in high volumes. The new devices also eliminate the usual trade-offs between magnet size, air volume, and sound quality that complicate both the design and integration of traditional, conventional electro-mechanical miniature speakers that contain a magnet and balanced-armature mechanism.
USound's patented concept for these speakers leverages piezo-electric material properties to drive the speaker membrane, which eliminates the complex signal processing required in other types of MEMS micro speakers. The piezo actuator allows an extremely small speaker footprint and low profile, with outstanding power efficiency and fast response for high acoustic performance.
ST's MEMS device-design competencies and manufacturing capabilities, including PeTra Thin-Film-Piezoelectric technology, enables the advanced speakers to be produced cost-effectively in high volumes and at high yield on silicon wafers, leveraging mature and well-characterized processes that are closely related to CMOS (Complementary Metal-Oxide-Semiconductor) chip fabrication.
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