Patent Review: A Circular Shaped Planar Speaker System

The patent in review was granted in February 2015 to inventor Zhijun Zhao (West Bloomfield, MI) on behalf of Harman International Industries. As James Croft notes, planar magnetic transducers are often preferred for their thin form factor, ideal for shallow mounting spaces where a standard transducer may not fit, such as in-wall systems and automotive applications. The patent in review offers a practical solution for an oval or circular format planar magnetic transducer for such applications. This article was original published in Voice Coil, April 2015.

James Croft reviews two loudspeaker-related patents as a tribute to David John Graebener, who passed away on January 3, 2015. First James Croft reviews the planar-magnetic electro-acoustic transducer he patented together with Graebener, followed by a single-end planar magnetic speaker system, David’s key patent. These were the first and second of the Single-Ended, Neodymium planar magnetic transducer patents David Graebener was granted. This article was originally published in Voice Coil, March 2015.

This patent review looks at a “Loudspeaker with a Wave Guide” (Patent Number: US20140369543) by inventors Jussi Vaisanen and Ilpo Martikainen from Finish company Genelec. This patent relates to the Genelec 8351 Acoustically Coaxial Smart Active Monitor (SAM) monitor, originally launched in 2016. Later in 2017, Genelec expanded the concept into a complete series of Coaxial Active Monitors, “The Ones”. This article was originally published in Voice Coil, February 2015.

James Croft reviews a patent claimed by Polk Audio and granted in 2015, describing “a single-enclosure loudspeaker system that projects multichannel surround sound into a listener’s room, and so replaces multiple conventional surround channel loudspeakers.” The patent also describes, in one embodiment of the invention, that the “surround channel program material is pre-processed by an integrated wireless transmission device that performs certain digital signal processing and channel mixing steps in advance of wireless surround signal broadcast to a receiver.” This article was originally published in Voice Coil, January 2015.

Every month on his Voice Coil's Acoustic Patents column, James Croft (Croft Acoustical) discusses different loudspeaker patents and inventions that are relevant to the audio industry. In the January 2015 edition. Croft reviewed a “Loudspeaker for Eliminating a Frequency Response Dip” patent, granted in November 12, 2014 to Harman International Industries, describing “a speaker system that includes a speaker enclosure having a front end, a rear end, and a first transducer. This article was originally published in Voice Coil, January 2015.