Prior art

To identify the most relevant prior art for US patent US9151557, I will use the patent's own citations from the USPTO database. Since I cannot directly access the USPTO database in an interactive way to retrieve full citation details and descriptions for each cited patent, I will outline the process for a human analyst to perform this task, and then provide a hypothetical example of what such an analysis would look like for a single prior art reference.

Process for identifying and describing prior art:

1. Access USPTO Patent Public Search: Navigate to the USPTO Patent Public Search website.
2. Search for US9151557: Use the "Quick lookup" or "Basic search" function to search for patent number US9151557. Ensure the search is for the exact patent number to avoid similar results.
3. Locate "References Cited" Section: Once the patent document for US9151557 is displayed, find the "References Cited" section. This section lists the prior art patents and publications that the examiner and applicant considered during the prosecution of US9151557.
4. Extract Information for Each Reference: For each listed prior art reference:
   • Full Citation: Record the patent number (or publication number), inventor(s), and issue/publication date.
   • Publication/Filing Date: Note the relevant date for anticipation analysis (usually the earliest of the filing or publication date).
   • Brief Description: Review the abstract and, if necessary, the claims and figures of the cited prior art to understand its core invention and how it relates to automatic sear assemblies or firearm mechanisms.
   • Potential Anticipation Analysis (35 U.S.C. § 102):
     • Compare the elements of each independent claim of US9151557 (Claims 1, 16, and 20 as previously summarized) to the disclosure of the prior art reference.
     • Determine if every element of an independent claim in US9151557 is found, either explicitly or inherently, in a single piece of prior art. If so, that prior art potentially anticipates that claim under 35 U.S.C. § 102.
     • Even if a prior art reference doesn't anticipate an entire independent claim, it's still highly relevant if it discloses many of the features, as it could be used in an obviousness argument under 35 U.S.C. § 103 (though the prompt specifically asks for anticipation).

Hypothetical Example of Prior Art Analysis (since I cannot perform live, in-depth analysis of specific prior art references):

Let's assume, for illustrative purposes, that one of the prior art references cited in US9151557 is US Patent 7,890,958 B2 to Smith et al. (This is a fictional example for demonstration).

Prior Art Reference: US7,890,958 B2
Full Citation: Smith et al., U.S. Patent No. 7,890,958 B2, issued February 15, 2011.
Publication/Filing Date: Filed: August 20, 2008; Issued: February 15, 2011.
Brief Description: This patent describes an automatic firing mechanism for a rifle that utilizes a pivoting sear and a separate trip lever. The trip lever is actuated by the bolt carrier's forward movement to release the hammer, enabling automatic fire. It also includes a selector switch mechanism that controls whether the trip lever engages the sear. The patent mentions the use of a torsion spring to bias the sear.
Potential Anticipation (35 U.S.C. § 102):

• Claim 1 of US9151557: US7,890,958 B2 appears to disclose:
  • An automatic sear configured to be operatively coupled with a safe/fire selector switch and a hammer.
  • A sear lever disposed adjacent a rear surface of the automatic sear.
  • A first spring configured to bias the sear lever into physical contact with the rear surface of the automatic sear (or a functionally equivalent biasing mechanism for the trip lever).
  • A second spring configured to operatively interface with the safe/fire selector switch (or a functionally equivalent spring for the selector mechanism).
  • Shared rotational axis for the sear and lever (or their functional equivalents).
  • Rotational deflection of the sear lever in a first direction causes it to rotate out of physical contact without imparting rotation to the sear.
  • Rotational deflection in a second direction imparts rotation to the automatic sear, causing it to sear with the hammer.
  • However, US7,890,958 B2 may not explicitly disclose the sear lever extending beyond a height of the automatic sear. If this specific height extension is not present in US7,890,958 B2, then it would not fully anticipate Claim 1.
• Claim 16 of US9151557: Similar to Claim 1, US7,890,958 B2 likely discloses many elements related to the rotational mounting, actuating portion of the sear, independent mounting of the sear lever, and biasing springs. The key distinction might again be the specific radial length relationship (the third radial length being greater than the first radial length by a specified distance). If US7,890,958 B2 does not detail this specific geometric relationship, it would not fully anticipate Claim 16.
• Claim 20 of US9151557: US7,890,958 B2 might disclose the use of helical torsion springs. However, it is less likely to specifically detail a helical double-torsion spring with first and second sets of coils wound in opposing directions, an unwound portion, and specific tangential and radial over-center legs, along with a bushing with a slot and a pin with a groove configured to align and receive the radial over-center leg. These specific structural details would likely differentiate Claim 20 from US7,890,958 B2, preventing full anticipation.

This hypothetical example illustrates the level of detail required for a thorough prior art analysis under 35 U.S.C. § 102, focusing on whether every element of a claim is present in a single prior art reference.