Linkplay Technology Inc v. Sonos Inc

1. Case Identification

• Case #: IPR2025-00509
• Patent #: 10,853,023
• Filed: February 1, 2025
• Petitioner(s): Linkplay Technology Inc.
• Patent Owner(s): Sonos, Inc.
• Challenged Claims: 1-17

2. Patent Overview

• Title: Audio Playback Devices with Smart Line-In Processing
• Brief Description: The ’023 patent discloses technology for audio playback devices that automatically switch from playing a first audio stream to a second, priority audio stream upon detecting a signal on a line-in connector. The system can override the current playback, play the priority audio, and then re-arm itself to detect the priority signal again after it ceases.

3. Grounds for Unpatentability

Ground 1: Anticipation and Obviousness over Barbe - Claims 1-17

• Prior Art Relied Upon: Barbe (Application # 2010/0325323).
• Core Argument for this Ground: Petitioner argued that all limitations of claims 1-17 are anticipated by Barbe under 35 U.S.C. §102. In the alternative, Petitioner asserted that certain dependent claims are obvious over Barbe under 35 U.S.C. §103.
  • Prior Art Mapping: Petitioner contended that Barbe discloses an audio system that automatically manages and selects from multiple audio sources. Barbe's system gives priority to a newly activated source, which preempts any currently playing source. For example, Barbe described a scenario where playing a Bluetooth audio stream (the "second type of media content") is automatically paused upon detection of an activated "line" source (the "first type of media content" received via a "line-in connector"). The system then plays the audio from the "line" source. When the "line" source is deactivated, Barbe's system is designed to resume the previous source (Bluetooth), which Petitioner argued constitutes the claimed ceasing playback and "rearming" of the device to again preempt playback upon subsequent activation of the priority source.
  • Motivation to Combine (for §103 grounds): For the alternative obviousness grounds against dependent claims (e.g., 3-6), Petitioner asserted that Barbe explicitly discloses or suggests features like playing in synchrony across multiple loudspeaker units to avoid echoes or enhance listener enjoyment, which a person of ordinary skill in the art (POSITA) would have found obvious to implement.
  • Expectation of Success (for §103 grounds): Petitioner argued a POSITA would have an expectation of success in implementing features like synchronized playback, as such techniques were well-known in multi-speaker and home theater systems at the time.

Ground 2: Anticipation and Obviousness over Richenstein - Claims 1-17

• Prior Art Relied Upon: Richenstein (Application # 2004/0157555).
• Core Argument for this Ground: Petitioner argued that all limitations of claims 1-17 are anticipated by Richenstein under §102. In the alternative, Petitioner asserted that the claims are obvious over Richenstein under §103.
  • Prior Art Mapping: Petitioner asserted that Richenstein discloses a wireless audio distribution system with an automatic channel selection feature that mirrors the claimed invention. Richenstein’s system was configured to "automatically override" a listener's selected audio channel (the "second type of media content") to play audio from a priority channel, such as a baby monitor or doorbell (the "first type of media content"), whenever the audio level on the priority channel exceeds a preset threshold. The priority audio was received via line-in connectors. Petitioner argued Richenstein further disclosed that the system can "automatically return to the stereo channel earlier selected" after the priority signal is no longer detected, which met the limitations of ceasing playback of the priority content and "rearming" the device.
  • Motivation to Combine (for §103 grounds): For the alternative obviousness grounds, Petitioner contended that Richenstein described its system's use with home theater systems and multiple speakers. A POSITA would have been motivated to implement claimed features like synchronized playback across multiple devices to create a conventional surround sound experience, which Richenstein explicitly contemplated.
  • Expectation of Success (for §103 grounds): Petitioner maintained that combining Richenstein’s priority channel feature with standard multi-speaker configurations would have been straightforward for a POSITA with a reasonable expectation of success, as the underlying technologies were well-established.

6. Arguments Regarding Discretionary Denial

• §325(d) Arguments: Petitioner argued against discretionary denial under 35 U.S.C. §325(d), asserting that neither Barbe nor Richenstein were previously presented to or considered by the USPTO during the prosecution of the ’023 patent. Petitioner contended that the examiner's allowance was based on the "dedicated line in connector," a feature expressly disclosed in both references, suggesting the patent would not have issued had this art been considered.
• Fintiv Factors (§314(a) Arguments): Petitioner argued the Fintiv factors strongly favor institution. Key arguments included that the co-pending district court trial was initially scheduled for May 2026, well after the August 2026 deadline for a Final Written Decision (FWD), and that scheduling uncertainty made a post-FWD trial even more likely. Further, Petitioner asserted that investment in the litigation has been minimal, with no substantive orders issued or claim construction completed.

7. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1-17 of the ’023 patent as unpatentable.