Two of Apple's latest patent filings about advanced stereo and home theater systems surfaced this month (one and two). The second patent filing that was discovered in Australia earlier this month was about a smart multi-speaker audio system designed for TV and live-streaming. Today the US Patent & Trademark Office published a patent application from Apple that delves deeper into the multi-speaker system in filing titled "A rotationally Symmetric Speaker Array." In many respects the patent shares some of the technology used with Apple's new HomePod equipped with spatial awareness but on a much larger scale. It's a system that could automatically analyze the acoustics, adjusts the sound based on the speaker's location, and steer the music in the optimal direction of the listener.
Patent Background
Speaker arrays are often used by computers and home electronics for outputting sound into a listening area. Each speaker array may be composed of multiple transducers that are arranged on a single plane or surface of an associated cabinet or casing. Since the transducers are arranged on a single surface, these speaker arrays must be manually oriented such that sound produced by each array is aimed at a particular target (e.g., a listener). For example, a speaker array may be initially oriented to directly face a listener. However, any movement of the speaker array and/or the listener may require manual adjustment of the array such that generated sound is again properly aimed at the target listener. This repeated adjustment and configuration may become time consuming and may provide a poor user experience.
Apple's Solution
Apple's invention covers a multi-way speaker array that includes one or more rings of transducers of different types. In one embodiment, the rings of transducers encircle the cabinet of the speaker array such that the speaker array is rotationally symmetric. This rotational symmetry allows the speaker array to be easily adapted to any placement within the listening area.
In particular, since the speaker array is rotationally symmetric, the same number and type of transducers are pointed in each direction. Once the orientation of the speaker array is known, the speaker array may be driven according to this orientation to produce one or more channels of audio without the need for movement and/or physical adjustment of the speaker array.
In some embodiments, the distance between rings of transducers may be based on a logarithmic scale. By separating rings of transducers using logarithmic spacing, denser transducer spacing at short wavelengths is achieved while limiting the number of transducers needed for longer wavelengths by spacing them in larger and larger logarithmic increments.
In these embodiments, multiple types of transducers may be used to generate beam patterns. By utilizing multiple transducers with overlapping frequency ranges, the speaker array may avoid initial dips or shortfalls in directivity for corresponding beam patterns.
Apple's patent FIG. 8 shows the speaker array rotationally symmetric about a center axis.
Apple notes that the rotationally symmetric enclosures can be shaped as one of a cylinder, a polyhedron, a frustum, a cone, a pyramid, a triangular prism, a hexagonal prism, and a sphere.
One of the keys to the system is that the rotational symmetry allows the speaker array #105 to be easily adapted to any placement within the listening area. For example, the speaker array may be associated with one or more sensors and logic circuits for detecting the orientation of the speaker array relative to the listener #107 and/or one or more objects in the listening area (e.g., walls in the listening area). For instance, the sensors may include microphones, cameras, accelerometers, or other similar devices. These sensors and logic circuits may be integrated with the speaker array and/or separate from the array (e.g., the sensors and logic circuits may be within or coupled to an audio receiver.
For example, one or more transducers in the speaker array may be driven to output a series of test sounds into the listening area. These test sounds may be detected by a set of microphones within the listening area. Based on the detected sounds, the orientation of the speaker array may be determined relative to one or more of the microphones, the listener, and/or one or more objects in the listening area. Since the speaker array is rotationally symmetric, the same number and type of transducers #109 are pointed in all directions. Accordingly, once the orientation of the speaker array is known, the speaker array may be driven according to this orientation to produce one or more channels of audio without the need for movement and/or physical adjustment of the speaker array.
To get the bigger picture you should read the more detailed patent that was published on August sixth which is like the master patent. Today's patents adds to the systems overview. Apple's patent application 20170238090 that was published today by USPTO was filed back in Q1 2017 with history dating back to 2014. Considering that this is a patent application, the timing of such a product to market is unknown at this time.
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