1:17-cv-00259
Implicit LLC v. Sonos Inc
I. Executive Summary and Procedural Information
- Parties & Counsel:
- Plaintiff: Implicit, LLC (Texas)
- Defendant: Sonos, Inc. (Delaware)
- Plaintiff’s Counsel: Farnan LLP; DiNovo Price Ellwanger & Hardy LLP
- Case Identification: 1:17-cv-00259, D. Del., 03/10/2017
- Venue Allegations: Venue is alleged to be proper in the District of Delaware because Defendant Sonos is a Delaware corporation, is subject to personal jurisdiction, and has allegedly committed acts of infringement within the district.
- Core Dispute: Plaintiff alleges that Defendant’s wireless multi-room audio products infringe two patents related to methods for synchronizing content playback across multiple networked devices.
- Technical Context: The technology addresses the challenge of maintaining precise audio/video synchronization among networked devices with independent clocks, a foundational requirement for the modern wireless home audio market.
- Key Procedural History: The complaint notes that the original patent assignee, Implicit Networks, Inc., was founded by one of the co-inventors and that its synchronization technology was previously used by companies including Intel and Motorola. This history may be raised to suggest early innovation and the non-obviousness of the patented methods.
Case Timeline
| Date | Event |
|---|---|
| 2001-12-17 | Priority Date for U.S. Patent No. 7,391,791 |
| 2001-12-17 | Priority Date for U.S. Patent No. 8,942,252 |
| 2008-06-24 | U.S. Patent No. 7,391,791 Issued |
| 2015-01-27 | U.S. Patent No. 8,942,252 Issued |
| 2017-03-10 | Complaint Filed |
II. Technology and Patent(s)-in-Suit Analysis
U.S. Patent No. 7,391,791 - “Method and System for Synchronization of Content Rendering” (Issued June 24, 2008)
The Invention Explained
- Problem Addressed: The patent describes the technical challenge of keeping multimedia presentations synchronized when rendered on different devices (e.g., video on a screen, audio on speakers) that have separate system clocks operating at slightly different frequencies, which can cause the content to "gradually appear... to be out of synchronization" (’791 Patent, col. 1:36-43).
- The Patented Solution: The system solves this problem by designating one device as a "master" and the others as "slaves" ('791 Patent, col. 2:28-32). The master device periodically sends an "indication" of its own rendering progress (its rendering time and corresponding device time) to the slave devices. The slave devices use this information to calculate a "time domain differential" and adjust their own playback—for example by skipping or duplicating content frames—to stay in sync with the master ('791 Patent, Abstract; col. 2:32-44).
- Technical Importance: The method provides a framework for maintaining tight playback correlation in networked multi-device systems, a foundational requirement for creating a seamless multi-room audio experience (Compl. ¶11).
Key Claims at a Glance
- The complaint explicitly recites and asserts independent claim 1 (Compl. ¶12).
- Essential elements of independent claim 1 include:
- designating one device as a "master device" and others as at least one "slave device";
- receiving content for rendering at the devices;
- "sending" from the master to the slave an "indication" of when the master renders content;
- "determining" a master device time domain, a slave device time domain, and a source time domain;
- "determining whether a time domain differential exists"; and
- "adjusting" the rendering at the slave device in proportion to the "time domain differential".
- The complaint alleges infringement of "one or more claims," reserving the right to assert others (Compl. ¶20).
U.S. Patent No. 8,942,252 - “Method and System Synchronization of Content Rendering” (Issued January 27, 2015)
The Invention Explained
- Problem Addressed: Like its parent, the ’252 patent addresses the problem of networked devices drifting out of sync due to operating in different time domains ('252 Patent, col. 1:41-48).
- The Patented Solution: The invention refines the synchronization process by having the master device send a "plurality of master rendering times" to a slave device. The slave device is then "configured to 'smooth' a rendering time differential" by performing "calculations using the plurality of master rendering times" ('252 Patent, Abstract; Claim 1). This use of multiple timing data points is intended to allow for more gradual and less abrupt playback corrections.
- Technical Importance: By using multiple data points to "smooth" adjustments, this method suggests a more robust and refined approach to synchronization that can better account for network jitter and avoid jarring playback corrections that might result from a single-point adjustment (Compl. ¶13).
Key Claims at a Glance
- The complaint explicitly recites and asserts independent claim 1 (Compl. ¶13).
- Essential elements of independent claim 1 include:
- a "master rendering device" rendering a first content stream;
- "sending", from the master to a slave, a "plurality of master rendering times";
- the slave device is "configured to smooth a rendering time differential" to render a second content stream synchronously; and
- the "smoothing" includes "calculations using the plurality of master rendering times".
- The complaint alleges infringement of "one or more claims," reserving the right to assert others (Compl. ¶33).
III. The Accused Instrumentality
Product Identification
The accused instrumentalities are Sonos's "wireless home sound system" products, including but not limited to "SonosNet, PLAY:1 speakers, PLAY:3 speakers, PLAY:5 speakers, CONNECT preamplifier, associated software and applications" (Compl. ¶21, ¶34).
Functionality and Market Context
The complaint alleges that the accused products allow users to "group" multiple speakers to play audio content synchronously (Compl. ¶16). When grouped, one speaker is designated as the "group coordinator" or "master," which is responsible for distributing the audio data and "timing information" to the other speakers in the group (Compl. ¶16). This functionality is illustrated in a Sonos system overview document excerpted in the complaint, which states a "lead player, called the group coordinator," is selected to distribute audio data to other group members (Compl. p.7). The complaint also provides a diagram from Sonos's documentation showing the components of its "Wireless HiFi System," including multiple speaker "zones," a controller, and a router (Compl. p.8, Figure 1).
IV. Analysis of Infringement Allegations
'791 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| designating one of the one or more devices a master device | When a user "groups" speakers, one speaker acts as the "coordinator or master for the group." | ¶16 | col. 2:28-32 |
| designating remaining devices ... as at least one slave device | The other speakers in the group are slaves that receive information from the master. | ¶16 | col. 2:30-32 |
| receiving the content for rendering by the master and at least one slave device | The master is "responsible for sending the content for rendering, e.g. music," to the other speakers. | ¶16 | col. 7:31-35 |
| sending from the master device to the at least one slave device an indication of when the master device renders content | The master sends "timing information to the other speakers in the group." | ¶16 | col. 2:35-37 |
| determining a master device time domain, a slave device time domain, and a source time domain | The devices are alleged to "utilize a master device with slave devices and various device times and rendering times." | ¶21 | col. 3:30-41 |
| determining whether a time domain differential exists | This is implied by the allegation that the devices use various times to render content synchronously. | ¶21 | col. 7:46-51 |
| adjusting, based on the received indication, the rendering of the content at the at least one slave device ... in proportion to the time domain differential | The core allegation is that the devices "render content at the master devices and slave devices synchronously." | ¶16, ¶21 | col. 2:37-44 |
'252 Patent Infringement Allegations
| Claim Element (from Independent Claim 1) | Alleged Infringing Functionality | Complaint Citation | Patent Citation |
|---|---|---|---|
| a master rendering device rendering a first content stream | The "coordinator or master" speaker in a group renders the audio content. | ¶16 | col. 4:20-22 |
| sending, from the master rendering device ... a plurality of master rendering times | The master sends "timing information" to the other speakers. The complaint alleges this constitutes a plurality of master rendering times. | ¶13, ¶16 | col. 8:43-48 |
| the first slave device is configured to smooth a rendering time differential... in order to render a second content stream ... synchronously | The accused system is alleged to achieve synchronous rendering between the master and slave devices. | ¶13, ¶16 | col. 8:49-54 |
| wherein smoothing the rendering time differential includes calculations using the plurality of master rendering times | This functionality is alleged based on the system's ability to achieve and maintain synchronicity. | ¶13, ¶34 | col. 8:55-57 |
Identified Points of Contention
Technical Questions
A primary question is what technical data comprises the "timing information" that the complaint alleges is sent from the Sonos master to slave devices (Compl. ¶16). The case may turn on whether discovery shows this information meets the claim requirements of an "indication of when the master device renders content" ('791 Patent) and a "plurality of master rendering times" used for "smoothing" ('252 Patent).
Scope Questions
The complaint's allegations for the "determining" steps of claim 1 of the ’791 patent are stated in conclusory terms (Compl. ¶21). A point of contention may be whether the Sonos system actually determines a "time domain differential" as specifically contemplated by the patent, or if it uses a different, non-infringing method to achieve synchronization.
V. Key Claim Terms for Construction
The Term: "time domain differential" ('791 Patent, Claim 1)
Context and Importance
This term is the central calculated value upon which the patented adjustment method relies. Infringement requires proving that the accused system calculates this specific value, not merely a generic timing correction. Practitioners may focus on this term to determine if the accused system's internal logic matches the patent's specific teachings.
Evidence for a Broader Interpretation
The specification suggests the general concept is to "account for the differences in the time domains of the other rendering devices" ('791 Patent, col. 3:28-32).
Evidence for a Narrower Interpretation
The specification discloses a specific formula for calculating the differential based on a two-way exchange of timing messages: "Diff=((RT1-ST1)+(ST2-RT2))/2" ('791 Patent, col. 3:61-63). A party could argue the term should be limited to a value derived from such a peer-to-peer calculation.
The Term: "smooth a rendering time differential" ('252 Patent, Claim 1)
Context and Importance
This phrase distinguishes claim 1 of the '252 patent and implies a more advanced process than a simple, one-time correction. The infringement analysis for this patent will depend heavily on whether the accused system's method of adjustment can be characterized as "smoothing."
Evidence for a Broader Interpretation
The specification states that the differential "can be smoothed using various techniques such as averaging the last several time domain differentials" ('252 Patent, col. 7:10-13), suggesting "smoothing" is a category of techniques rather than one specific algorithm.
Evidence for a Narrower Interpretation
The patent provides a specific example of "smoothing," which involves using "the last eight pairs of time domain differentials" ('252 Patent, col. 7:15-17). A party could argue that "smoothing" requires a specific type of multi-point, time-averaged calculation, and a different adjustment method would not meet this limitation.
VI. Other Allegations
Indirect Infringement
The complaint alleges inducement of infringement for both patents. The factual basis is Sonos's alleged actions of providing instructions, tutorials, product guides, and advertising that encourage end-users to operate the accused products in an infringing manner (i.e., by grouping speakers for synchronous playback) (Compl. ¶26, ¶39).
Willful Infringement
The complaint does not use the word "willful," but it alleges that Sonos had knowledge of the patents and the infringing nature of its activities "at least as early as the date when Implicit effected service of this Complaint" (Compl. ¶23, ¶36). This establishes a basis for potential post-suit willful infringement claims. No facts are alleged to support pre-suit knowledge.
VII. Analyst’s Conclusion: Key Questions for the Case
- A key evidentiary question will be one of technical implementation: what specific data constitutes the "timing information" (Compl. ¶16) exchanged between Sonos devices? Does this data and its subsequent use by the slave devices map directly onto the claimed "time domain differential" of the ’791 patent and the "smoothing" calculations using a "plurality of master rendering times" required by the ’252 patent? The complaint makes these allegations but provides limited supporting technical detail.
- The case may also turn on a question of claim scope: can the term "smooth a rendering time differential" from the ’252 patent be construed broadly to cover any method that results in synchronized audio without perceptible artifacts, or will it be limited to a more specific mathematical process, such as the multi-point averaging techniques described in the specification? The resolution of this question could be dispositive for the infringement analysis of the ’252 patent.