Signal Processing Claims Found to be Patent Eligible
In the U.S. District Court for the Central District of California, Hybrid Audio, LLC sued Visual Land, Inc. for patent infringement with respect to audio signal processing technology used in conjunction with MP3 technologies. Defendant filed a motion to dismiss, alleging that the patent was invalid under 35 U.S.C. § 101. Despite seemingly very broad claims, the Court found that it was clear from the asserted patent that the claims were directed to an improvement in the functioning of a computer, and thus, were patent eligible.
The patent at issue is entitled "Signal Processing Utilizing a Tree-Structured Array," which originally issued as U.S. Patent No. 6,252,909 on June 26, 2001. After a reissue application was filed for the '909 Patent, the '909 Patent reissued with certificate number RE40,281, and subsequently, a request for reexamination of the '281 Patent was filed, and the PTO issued a reexamination certificate for the '281 Patent confirming patentability of the reexamined claims.
The '281 patent describes a communication system for sending a sequence of symbols on a communication link, and the system includes a transmitter for placing information indicative of the sequence of symbols on the communication link and a receiver for receiving the information placed on the communication link by the transmitter. An input data stream is received by a symbol generator that converts a run of data bits from the input stream into M symbols S1, S2, . . . , SM for transmission. The transmitter treats the symbols Si as if they were the amplitude of a signal in a narrow frequency band. For efficient design, each sub-channel must be sufficiently narrow to allow the distortions in that sub-channel to be modeled by a single phase shift and attenuation. This occurs through decomposition of a signal into frequency sub-bands by a tree structured filter as shown in Figure 2 of the '281 patent, which is reproduced below. At the receiving end of transmission link, the transmission segment is recovered.
Claims 5 and 18 are representative of the asserted claims in the '281 Patent, and are reproduced below:
5. A signal processing method comprising:
splitting a signal into subbands using a plurality of filter banks connected to form a tree-structured array having a root node and greater than two leaf nodes, each node comprising one filter bank having greater than two filters, and at least one of the leaf nodes having a number of filters that differs from the numbers of filters in a second leaf node.
18. A signal processing method comprising:
synthesizing a signal using a plurality of synthesis filter banks connected to form a tree-structured array having greater than two leaf nodes and a root nod, wherein each of the nodes comprises one synthesis filter bank having a number of filters that differs from the number of filters in a second leaf node.
Put more simply, claim 5 focuses on the splitting of the audio signal for transmission, while claim 18 focuses on the synthesizing of the processed signal after reception.
Patent Eligibility Under 35 U.S.C. § 101
The Defendant asserted two patent-eligibility challenges to the '281 patent, each of which is summarized below.
1. Nuijten Analysis
First, the Defendant argued that the '281 Patent is patent-ineligible under the holding in In re Nuijten, 500 F.3d 1346 (Fed. Cir. 2007). In Nuijten, the Federal Circuit decided (prior to both Mayo and Alice), that transitory signals did not fall within one of the four categories of patentable subject matter and thus were patent ineligible. In Nuijten, the Federal Circuit allowed processing claims, but clearly denied patent eligibility for claims that covered the signals themselves.
Here, the Court found that claims 5 and 18 describe the process of splitting and synthesizing signals, rather than claiming the signals per se. In fact, both claims begin with, "A signal processing method." Since both claims are processing claims, neither claim covers a signal per se, and thus, a Nuijten analysis was deemed unnecessary.
2. Alice Analysis
Next, the Defendant argued that the '281 Patent is patent-ineligible under the holding in Alice. Under the two-step framework established in Alice, the court first asks "whether the claims at issue are directed to one of those patent-ineligible concepts," as opposed to "patent eligible applications of those concepts." If so, the court then "consider[s] the elements of each claim both individually and 'as an ordered combination' to determine whether the additional elements 'transform the nature of the claim' into a patent-eligible application."
The Defendant argued that the asserted claims are directed to the abstract idea of splitting and combining signals into a tree-structured array. This characterization of the claims as being directed to "splitting and combining signals into a tree-structured array," appears correct, but whether such actions are indeed an "abstract idea" was argued at length.
To support their allegations, the Defendant argued that the asserted claims are not directed to an improvement in computer technology and are instead an abstract idea implemented on a general purpose computer.
The Court found that it was clear from the '281 Patent that the claims are directed to an improvement in the functioning of a computer. The claimed invention purported to require less computational capability than the prior art, and further allowed the quality of the playback to be varied in response to the computational capability of the playback platform without the use of multiple copies of the compressed material, as described in the patent.
The claimed invention aimed to solve this problem and allowed for quality playback without the aliasing, or distortion, effects of the prior art. Ultimately, the claimed invention makes computers more efficient without sacrificing the quality of the sound, thus making the claims patent eligible. This reasoning was supported throughout the patent description making the decision easy to support.
The Court further found the patent at issue to be similar to that in a prior district court case (Audio MPEG, Inc. v. HP Inc., No. 2:15-cv-00073-HCM-RJK, 2016 U.S. Dist. LEXIS 181710, at *38 (E.D. Va. June 29, 2016), in which audio files were compressed and stored using much less space, and claims of that scope were found patent eligible. For example, in Audio MPEG, the Defendant argued that the plaintiffs were trying to patent mathematical formulas, an abstract idea. However, the court in Audio MPEG noted that the plaintiffs were not seeking to patent a mathematical formula or the general idea of receiving and outputting information, but rather, claims directed to encode and decode a wide-band signal in a manner that takes into account the hearing capabilities of the human ear to produce a realistic replica of the original signal with the minimal amount of data. The court found this to be a patent-eligible concept and thus denied Defendant's motion at step one of Alice.
Likewise, here, the Court found that the '281 Patent involves a similar process of compressing and decompressing an audio signal, taking into account the capabilities of the human ear and reducing the computational power needed. The asserted claims were thus found to resemble those at issue in Enfish and Audio MPEG—claims directed to patent-eligible concepts.
Thus, despite broad claims that recite only functional aspects, and no physical components or elements that perform the functions, the claims were found to be patent eligible because the patent disclosure clearly set forth how the claimed processes improved computer functionality as compared to prior art. This enable the plaintiff to show that the claims were necessarily rooted in computer technology, solved a technical problem with a technical solution, and improved upon prior computer technology—all factors weighing in favor of patent eligibility.
Order by Senior District Judge Ronald S.W. Lew
