Patent Review: Two Pioneer Patents. Same Speaker Invention

This article reviews two patents titled simply "Speaker Device" from four Japanese inventors, on behalf of Pioneer Corp. of Japan. The original and expanded patent describes a flat speaker device capable of emitting loud reproduced sound, using a mechanical structure that converts a linear voice coil motion in one axis to an orthogonal mechanical diaphragm displacement. The system functions much like a scissor-jack you would use to raise your automobile to change a tire. The linear motion of the threaded rod coverts the axial force to a 90° lift movement.

This patent, granted to MrSpeakers, the company from San Diego, CA that is now Dan Clark Audio, was granted in the same month that this review was published in Voice Coil. The patent details a headphone driver that should also be of note for the speaker industry. As Croft notes, the patent office initially rejected the claims due to prior patents, eventually accepting the inventor's arguments, in 2016. The review provides the historical context for planar magnetic transducers, and explains why this is an important patent.

This article examines a notable patent from VUE Audiotechnik, describing a loudspeaker system with one driver providing a direct radiating output from the front, and a second driver on a ported side chamber, sharing a ported common chamber, where at least one port of the ported common chamber exits the front of the loudspeaker system. As Croft notes, this is an innovative advanced system - that was patent-pending at the time - and provides a unique combination of technology, offering real-world advantages. The patent was granted in 2021.

This review highlights a patent granted to Bose Corp, part of an interesting series of bass reflex and tuned pipe enclosure architectures explored by Bose, which James Croft reviews and explains in detail. The patent describes a single chamber, single tuned, bass reflex enclosure system, using a more advanced, single Helmholtz tuned bass reflex design, with a port that is folded and extended. A great patent review with lots of informative details. This article was originally published in Voice Coil, October 2017.

Voice Coil June 2023 features an extensive patent review in James Croft's Acoustic Patents column. The topic is a 2014 patent awarded to Nokia, offering an opportunity to revisit the history of electrostatic loudspeakers, with insights from Tim Mellow, one of the two listed inventors. In Test Bench, Vance Dickason focuses on the D8404-552000 Ellipticor cloth diaphragm dome midrange from Scan-Speak, and characterizes the SB Acoustics TW29BNWG beryllium dome and waveguide from the brand's prestigious Satori line.

This review looks at a speaker patent, awarded to inventor Shengbo Li from Guangdong, China, on behalf of Harman International. The abstract from that patent details a speaker including one or multiple transducers, an enclosure, and a suspension mounted on the enclosure, wherein the suspension and the enclosure are configured such that the enclosure is capable of vibrating as a result of operation of the transducer so as to produce audible sound. You read it right, the enclosure is also a passive radiator!

This patent awarded to inventor Matthias Larrieu, on behalf of French company NEXO (owned by Yamaha Corp.) was the topic of this detailed review by James Croft. From the abstract it might be difficult to visualize what exactly differentiates the patented design from a standard bass reflex system. Basically, Larrieu created two V-shaped slices at the opening either centered or with one at each side of the port, helping to reduce amplitude and phase anomalies in the midrange due to port resonances, while improving mid-band directivity.

This article examines an important patent filed in 2014 by F. Bruce Thigpen (Tallahassee, FL) and granted in June 2016. Appearing both as the inventor and assignee, Thigpen describes a rotary sound transducer having an improved output at higher frequencies. Thigpen has been working on this type of device for more than a decade and has advanced what was already a very difficult engineering achievement, to a more sophisticated structure that apparently raises the general performance and high frequency limits beyond what was thought possible with this architecture. This article was originally published in Voice Coil, July 2017.

The April 2023 issue of Voice Coil reveals the genesis of Echo Test + Measurement and its AIO Test System. As scheduled, there's an updated industry directory of Cable and Connector vendors, James Croft reviews a key Polk Audio patent that expands on its Polk SDA loudspeaker prior art now in a more compact enclosure. And on Test Bench, Vance Dickason focus on the characterization of the innovative TW045WA01 dual-diaphragm tweeter from Wavecor.

This review addresses an important patent awarded to Joseph F. Pinkerton (Austin, TX), on behalf of Clean Energy Labs, LLC. The patent describes an audio speaker having one or more passive radiators, and more specifically, an audio speaker having a passive radiator with dynamically adjustable resonant frequency. Croft reviews the patent and compares it with previous attempts to achieve this useful development, with significant potential if its full capability is realized.