On March 07, 2013, the US Patent & Trademark Office published ten original patent applications from Apple. In this report we focus on Apple's invention regarding a new speaker system that integrates a sound radiating surface. We covered Apple's original work on this sound system back in 2012 in our report titled "Apple Reinvents Speakerphone System for iOS Devices."
Apple's Patent Background
In modern consumer electronics, audio capability is playing an increasingly larger role as improvements in digital audio signal processing and audio content delivery continue to happen. There is a range of consumer electronics devices that are not dedicated or specialized audio playback devices, yet can benefit from improved audio performance. For instance, smartphones are ubiquitous. These devices, however, do not have sufficient space to house high fidelity speakers. This is also true for portable personal computers such as laptop, notebook, and tablet computers, and, to a lesser extent, desktop personal computers with built-in speakers. Such devices typically require speaker enclosures or boxes that have a relatively low rise (i.e. height as defined along the z-axis) and small back volume, as compared to, for instance, standalone high fidelity speakers and dedicated digital music systems for handheld media players.
In low rise speaker boxes, there is an advantage to using speakers that maintain a high "Bl" product in order to reduce low frequency displacement (this prevents high total harmonic distortion (THD), rub and buzz) and to increase the sensitivity. In conventional speakers, the magnet unit thickness is typically reduced as the box thickness is reduced to allow for airflow around the transducer. The reduced z height of the magnet system means that the force generated by the coil is smaller (when an audio signal is being applied to the speaker). Therefore, any gains in THD, rub, buzz and sensitivity are lost due to the lower force that is generated by the coil and magnet system.
Previous efforts to address this problem have focused on including additional voice coil and magnet systems forming a push pull system within the enclosure to increase the "Bl" product and hence the sound output. Such systems, however, often require a significant increase in the height of the enclosure in order to maintain sufficient air flow through the system.
A New Speaker Assembly with a Sound Radiating Surface
Apple's invention relates to a speaker assembly having an enclosure with an acoustic output opening, an acoustic chamber, and a speaker driver. The speaker driver includes a sound radiating surface, first and second voice coils positioned along opposite faces, respectively, of the sound radiating surface, and first and second magnet assemblies having elongated gaps within which portions of the first and second voice coils are positioned to vibrate.
The first magnet assembly elongated gap can be orientated lengthwise toward the acoustic output opening, while the second magnet assembly elongated gap is oriented lengthwise toward the acoustic chamber. The elongated gaps may be used as air flow paths to direct a flow of air toward the acoustic output opening and toward the acoustic chamber so that a height or rise of the enclosure need not be significantly increased to accommodate the stacked voice coil and magnet assembly configuration.
As noted below in Apple's patent FIG. 6, the speaker may be a speakerphone unit that is integrated within an iPhone or iPad with which a user can conduct a FaceTime call.
Apple's patent FIG. 1illustrated below is a perspective view of a speaker having a dual voice coil driver. The speaker is built right into the frame. The speaker (100) may include a dual voice coil driver a having first magnet assembly (104) and a second magnet assembly (106).
Each of first magnet assembly and second magnet assembly may define gaps within which a portion of the coils may be positioned to produce a push pull speaker system. In other words, one the of coils acts to "push" the sound radiating surface while the other coil simultaneously "pulls" the sound radiating surface in the same direction.
The sound radiating surface may be coupled to the frame by way of suspension as shown in FIGS. 2A and 2B below.
Apple's patent FIG. 3 is a top exploded view of the embodiment of patent FIG. 1 noted above.
Apple credits Christopher Wilk as the sole inventor of this patent application which was originally filed under serial number 226383 in Q3 2011.
A Word about Continuation Patents
It should be noted that the US Patent and Trademark Office did in fact publish two older continuation patents today dating back to between 2004 and 2009. The continuation patents listed below are specifically referenced as such under the section titled "Cross-Reference to Related Applications." Generally speaking, this type of patent application contains modifications that Apple's legal team have made to the original patent claims in an effort to have the US Patent Office finally approve their invention. In general continuation patents don't represent any new developments from the original patent filing. Some websites mistakenly report on continuation patents as if they were new Apple filings to which they are not. Here are the older continuation patents that were published today by the US Patent Office:
1. A 2004 Patent Application (20130058355) Methods and Apparatus for Ensuring Compatibility on a High Performance Serial Bus
2. A 2009 Patent Application (20130061314) Secure Software Installation
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