HP Inc v. Memjet Technology Ltd

1. Case Identification

• Case #: IPR2016-00537
• Patent #: 7,156,492
• Filed: January 29, 2016
• Petitioner(s): HP Inc.
• Patent Owner(s): Memjet Technology Ltd
• Challenged Claims: 1, 2, 4, and 5

2. Patent Overview

• Title: Modular Printhead Assembly
• Brief Description: The ’492 patent describes a modular printhead assembly for a pagewidth inkjet printer. The assembly features replaceable printhead modules mounted on an elongate fluid transporter, which is in turn received within a metal alloy carrier that provides structural support.

3. Grounds for Unpatentability

Ground 1: Claims 1, 2, and 4 are obvious over Cowger in view of Silverbrook 2172.

• Prior Art Relied Upon: Cowger (Patent 5,565,900) and Silverbrook 2172 (WO 01/02172).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Cowger disclosed all limitations of independent claim 1 except for the carrier being made of a "metal alloy." Cowger taught a modular printhead with a "substantially rigid body" (the carrier) that receives removable print head assemblies. These assemblies include a component analogous to the claimed fluid transporter ("carrier 40") defining multiple ink passageways, and print heads (the printing modules) mounted to it. Silverbrook 2172, in the same field, explicitly disclosed a support structure ("profile member 10") made from an "aluminium alloy extrusion" to serve as a frame for printhead segments. For dependent claim 2, Petitioner asserted Cowger disclosed a flexible printed circuit board ("ribbon-type multiconductor 26" and "flexible circuit 54") located between the carrier and transporter. For dependent claim 4, Petitioner argued Cowger's carrier ("pen body 24") included a recessed surface between protruding lips, forming the claimed "channel member."
  • Motivation to Combine: A POSITA would combine these references to improve the performance of Cowger's assembly. Using a metal alloy carrier as taught by Silverbrook 2172 for Cowger's rigid body would be an obvious design choice to enhance rigidity, elasticity for clamping forces, and heat conductivity, all known advantages of metal alloys for pagewidth printer frames.
  • Expectation of Success: A POSITA would expect success in substituting a known material (metal alloy) for its known beneficial properties in a known application (printer support structure).

Ground 2: Claims 1, 2, and 4 are obvious over Silverbrook 142 in view of Silverbrook 2172.

• Prior Art Relied Upon: Silverbrook 142 (Patent 6,428,142) and Silverbrook 2172 (WO 01/02172).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner contended that Silverbrook 142, from a similar set of inventors, disclosed a modular pagewidth printhead assembly with all elements of claim 1. It taught a "chassis 14" made of "sheet metal" (the carrier) that supports an "ink reservoir 16" (the fluid transporter). This reservoir had four ink channels for CMYK printing and had replaceable printhead modules attached to it. To the extent "sheet metal" was not considered a "metal alloy," Petitioner argued Silverbrook 2172 supplied this missing element with its teaching of an aluminum alloy extrusion. For dependent claim 2, Silverbrook 142 disclosed a "flexible printed circuit board (PCB) 54" located between the carrier's sidewall and the ink reservoir. For dependent claim 4, Petitioner asserted that the chassis and sidewalls of Silverbrook 142 together formed a channel member.
  • Motivation to Combine: A POSITA would be motivated to combine Silverbrook 2172 with Silverbrook 142 for the same reasons as with Cowger: to use a known material with superior properties (an aluminum alloy) for the support chassis to improve strength, prevent sagging, and enhance thermal performance.
  • Expectation of Success: The combination represented a predictable implementation of known design principles and material science in the field of inkjet printers.

Ground 3: Claim 5 is obvious over the primary combinations in light of Bohorquez.

• Prior Art Relied Upon: Cowger, Silverbrook 2172, and Silverbrook 142 as the base combinations, with the addition of Bohorquez (Patent 5,682,186).
• Core Argument for this Ground:
  • Prior Art Mapping: Claim 5 adds the limitation of "a capping arrangement for capping the printing modules is mounted on the carrier." Petitioner argued that neither of the primary combinations explicitly disclosed this feature. Bohorquez, also directed to pagewidth inkjet printers, taught a "protective cap 82" mounted to the print head structure to shield the ink-jet nozzles.
  • Motivation to Combine: A POSITA would be motivated to add the capping arrangement from Bohorquez to the assemblies of either primary combination to solve the well-known problem of ink nozzles becoming contaminated, drying out, or gumming up from exposure to dust and air. Protecting nozzles with a cap was a known solution to a known problem.
  • Expectation of Success: Incorporating a known type of protective cap onto a printhead assembly would have been a straightforward and predictable modification for a POSITA.

4. Key Claim Construction Positions

• "carrier": Petitioner proposed this term be construed as a "support structure." This construction was argued to be consistent with the specification, which uses "support structure" and "metal channel" to describe the function of holding the printhead modules in place, and was necessary to read the claims on prior art that used different terminology (e.g., "chassis" or "pen body").
• "that can each transport a respective type of fluid": Petitioner argued this phrase, describing the function of the fluid transporter's channels, should be given no patentable weight. The argument was based on the legal principle that apparatus claims are not made patentable by statements of intended use or the properties of materials intended to be used with the apparatus.
• "the carrier, in the form of a channel member": For dependent claim 4, Petitioner proposed this be construed as "the support structure, having a floor and a pair of opposed side walls." This was based on language in the specification describing an embodiment with these features.

5. Arguments Regarding Discretionary Denial

• Petitioner acknowledged that Silverbrook 2172 was considered during the original prosecution of the ’492 patent. However, Petitioner argued that an inter partes review (IPR) should still be instituted under 35 U.S.C. §325(d) because the specific invalidity arguments and combinations presented in the petition were not previously considered by the USPTO.

6. Relief Requested

• Petitioner requested institution of an IPR and cancellation of claims 1, 2, 4, and 5 of the ’492 patent as unpatentable under 35 U.S.C. §103.