PTAB

IPR2019-00990

MCP IP LLC v. Craig Yehle

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Key Events
Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Cable-Synchronized Dual-Cam Archery Bow
  • Brief Description: The ’979 patent discloses a cable-synchronized, dual-cam compound archery bow. The invention centers on specific arrangements of cam assemblies, including power cable take-up and let-out mechanisms, designed to prevent the bow from reaching a 100% let-off condition, which can cause undesirable "cocking" where the bow locks at full draw.

3. Grounds for Unpatentability

Ground 1: Claims 1-6, 8-17, and 19-22 are obvious over Darlington in view of Wing.

  • Prior Art Relied Upon: Darlington (Patent 6,990,970) and Wing (a 1976 article in BOW & ARROW).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Darlington discloses the fundamental structure of a synchronized dual-cam bow, including a handle, flexible limbs, and first and second power cams rotatably mounted on the limbs. Darlington further shows a draw cable (bowstring) and two power cables that engage with take-up and let-out grooves on the cams, meeting most limitations of independent claim 1. The critical limitation added during prosecution to achieve allowance—arranging the cams to "avoid 100% let-off"—is taught by Wing. Petitioner's expert analyzed photographs from the Wing article evaluating the "Impact II" bow and calculated specific lever arm ratios. These calculations showed that the ratio of the take-up lever arm to the let-out lever arm remained greater than 1:1 throughout the draw cycle (3.6:1 at brace, 1.2:1 at full draw), which physically prevents a 100% let-off condition.
    • Motivation to Combine (for §103 grounds): A person of ordinary skill in the art (POSITA) designing a bow based on Darlington would be motivated to incorporate the teachings of Wing for safety and functionality. The petition asserted that a bow capable of 100% let-off is unsafe, as it can become "cocked" and difficult to manage. A POSITA would combine Wing's known cam geometries, which ensure the bow operates below 100% let-off, with Darlington's modern bow structure to create a safe and reliable product.
    • Expectation of Success (for §103 grounds): Both references describe synchronized dual-cam bows operating on identical mechanical principles, making the incorporation of specific cam profiles and lever arm ratios from Wing into the general structure of Darlington a predictable modification with a high expectation of success.

Ground 2: Claims 7 and 18 are obvious over Darlington in view of Wing and Kam-Act.

  • Prior Art Relied Upon: Darlington (Patent 6,990,970), Wing (a 1976 article in BOW & ARROW), and Kam-Act (a 1974 article in BOW & ARROW).
  • Core Argument for this Ground: This ground addresses the additional limitation in claims 7 and 18 requiring the position of the rotation stop to be adjustable.
    • Prior Art Mapping: Petitioner asserted that the base combination of Darlington and Wing teaches all elements of these claims except for the adjustability of the rotation stop. Darlington itself discloses using fixed rotation stops (132, 134) that engage the power cables at full draw to limit cam movement. The Kam-Act reference, an advertisement for the "Kam-Act MK-2" bow, was introduced to teach that making such stops selectively repositionable was a known feature for adjusting draw length. The advertisement explicitly illustrates a "DRAW STOP" on the cam that "can be adjusted to any setting from 25" to 31" draw length," demonstrating a repositionable stop to control the point of full draw.
    • Motivation to Combine (for §103 grounds): A POSITA would combine the teachings of Kam-Act with the Darlington/Wing bow to enhance its versatility. Providing an adjustable draw stop allows an archer to customize the bow to specific preferences, a highly desirable feature, representing a simple combination of known elements to achieve a predictable improvement.
    • Expectation of Success (for §103 grounds): Adding a known adjustability feature from Kam-Act to a known component (the rotation stop in Darlington) is a straightforward mechanical design choice that would have been easily implemented by a POSITA with a very high expectation of success.

4. Key Claim Construction Positions

  • "Lever arm of the power cable take-up/let-out mechanism": Petitioner contended this term should be construed as "the perpendicular distance between the force vector of the corresponding power cable and the reference location (axis of rotation)." This construction, based on standard physics principles for torque calculation, was central to Petitioner's ability to analyze and apply the lever arm ratios disclosed in the prior art figures of Wing.
  • "arranged so as to avoid 100% let-off...": Petitioner proposed this phrase means "shaped or positioned to provide a reduction in the holding force when the bow is fully drawn relative to the peak force it initially took to get the bow drawn all the way back." This construction links the claimed functional language to the physical geometry and lever arm ratios of the cams, which Petitioner argued were explicitly disclosed in the prior art.

5. Key Technical Contentions (Beyond Claim Construction)

  • Petitioner's primary technical contention challenged the patentee's arguments during prosecution that overcoming prior art required "suitable sizes or relative proportions" not disclosed by the primary reference (Ketchum). Petitioner argued that in a cable-synchronized dual-cam bow, the prevention of 100% let-off is determined strictly by the ratio of the take-up (TU) lever arm to the let-out (LO) lever arm. So long as the TU/LO ratio remains greater than 1:1 throughout the draw cycle, 100% let-off is physically impossible, regardless of the absolute size of the cams. Petitioner asserted this critical ratio was disclosed in the prior art, particularly in Wing, undermining the basis for patentability argued to the Examiner.

6. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-22 of the ’979 patent as unpatentable.