PTAB

IPR2020-00593

Ashworth Bros Inc v. Laitram LLC

Title: Positive-Drive Spiral Conveyor
Brief Description: The ’388 patent describes a positive-drive spiral conveyor system where a conveyor belt travels a helical path around a rotating drive tower. The invention focuses on the configuration of drive members on the tower, which have outwardly projecting ridges at a varying distance from the tower's vertical axis to engage the belt without slip and reduce belt tension.

Prior Art Relied Upon: Pupp (Patent 6,062,375) and Roinestad (Patent 3,348,659).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Pupp discloses the core elements of the challenged claims, including a positive-drive spiral conveyor with a belt driven "without slip" by ridges on drive members engaging the inside edge of the belt. However, Pupp's drive tower is substantially cylindrical. Roinestad was cited for its teaching of using conical or tapered drive towers (or towers with tapered sections) as a known method to smoothly drive a conveyor belt under low tension.
- Motivation to Combine: A POSITA would combine Pupp's positive, no-slip drive mechanism with Roinestad's tapered tower geometry. The motivation would be to achieve a well-known goal in the art: creating a conveyor system that is both positively driven to prevent slippage and operates under reduced belt tension to improve reliability and reduce wear. This combination addresses known problems with predictable solutions from the prior art.
- Expectation of Success: A POSITA would have a high expectation of success because combining a known drive mechanism (Pupp) with a known tower geometry (Roinestad) involves the application of familiar design principles to achieve a predictable improvement in performance.

Prior Art Relied Upon: Heber (Patent 7,347,316).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner asserted that Heber, on its own, discloses every limitation of the challenged claims. Heber teaches a spiral conveyor with a conical guide ring (drive tower) whose outer surface tapers, thus meeting the limitation of drive members whose distance from the vertical axis varies. Crucially, Heber explicitly incorporates by reference the Pupp patent, which discloses a conveyor belt positively driven "without slip" by ridges engaging an inside edge of the belt. Petitioner argued that the teachings of Pupp are therefore legally part of the Heber reference.
- Key Aspects: A central argument was that the Patent Examiner overlooked Heber's incorporation by reference of Pupp during prosecution. The patentee allegedly secured allowance by adding the "without slip" limitation, arguing it was absent from the art of record (Heber and Irwin), while failing to acknowledge that Heber incorporated a reference (Pupp) that explicitly taught it.

Prior Art Relied Upon: Roinestad2 (Patent 4,741,430) and Roinestad (Patent 3,348,659).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Roinestad2 teaches a positive-drive spiral conveyor with a cylindrical cage and vertical driving bars that have outwardly projecting ridges to engage the belt. Roinestad, from the same inventor, teaches various drive tower geometries, including fully tapered towers and towers combining cylindrical and tapered sections to reduce belt tension.
- Motivation to Combine: A POSITA would be motivated to apply the known, advantageous tower geometries from Roinestad to the positive-drive system of Roinestad2. The goal would be to improve the Roinestad2 system by incorporating a feature (tapering) explicitly designed to reduce friction-induced stress and allow for smoother, low-tension operation, a stated object of the Roinestad patent.
- Expectation of Success: The combination would be a predictable matter of routine design choice, as it involves applying a known tension-reduction technique from one reference to a similar conveyor system from another reference by the same inventor.
Additional Grounds: Petitioner asserted additional obviousness challenges over Heber alone (Ground III) and Heber in view of Roinestad (Ground IV), relying on similar arguments that Heber's teachings, particularly when combined with the incorporated teachings of Pupp, rendered the claims obvious.

Petitioner argued for two alternative constructions of the term "without slip," which was added during prosecution to overcome a rejection:
- Plain and Ordinary Meaning: The term's plain meaning to a POSITA is a structure or method that maintains the correct balance of belt tension and eliminates "overdrive" (where the drive surface moves faster than the belt edge).
- Prosecution History Construction: Alternatively, the patentee defined the term during prosecution by tying it to the specific geometry and engagement shown in Figures 2A, 2B, and 2C of the ’388 patent.
- Petitioner contended that the prior art, particularly the incorporated teachings of Pupp, discloses a "without slip" system that meets the claim limitations under either construction.

A core technical contention was that a POSITA would understand a disclosure of a "substantially cylindrical" drive tower to inherently suggest the well-known design alternative of a slightly conical or tapered tower. This was a known technique to reduce belt tension. This argument was used to assert that references like Pupp, which show a cylindrical tower, would readily suggest to a POSITA the obviousness of modifying that tower to be tapered, as taught by references like Roinestad.

Petitioner requested institution of an inter partes review and cancellation of claims 9-13 of the ’388 patent as unpatentable.