US 7302042

Here's a concise summary of US Patent 7,302,042:

Title: Remote bladder venting and containment system

Assignee: Varian Medical Systems Inc.

Inventors: Wayne Rollins Hansen, Ricky Smith

Filing Date: 2006-04-28

Issue Date: 2007-11-27

Abstract: The patent describes a system for remotely venting an expansion bladder in a liquid-filled container, such as an X-ray tube's outer housing. This remote venting setup allows the expansion bladder to access atmospheric pressure, enabling it to compensate for pressure changes within the liquid-filled container caused by liquid heating. The remote design permits the expansion bladder to be located within a radiation-shielded area of the housing, while the venting component is in an unshielded region. This eliminates the need to compromise the radiation shielding to provide atmospheric access to the bladder. Additionally, the remote vent is semi-permeable to prevent liquid leakage if the bladder ruptures.

Plain-Language Overview of Independent Claims:

• Claim 1: An X-ray tube with a remotely vented bladder in a transparent region.
  This claim describes an X-ray tube that includes an outer housing filled with a cooling liquid, and an internal evacuated enclosure (where X-rays are generated). Within this outer housing is a flexible expansion bladder with an air-filled interior. The inventive aspect is a "port" (an opening or vent) in the outer housing that provides atmospheric pressure to the bladder's interior through an air passageway. Crucially, this port is located in a part of the outer housing that allows X-rays to pass through it, rather than in a radiation-shielded area.

• Claim 8: A remote bladder venting system for an X-ray tube with separated shielded and unshielded components.
  This claim defines a remote venting system for an X-ray tube. It includes an expansion bladder placed in a part of the X-ray tube housing that is designed to block X-rays (non-transmissive). A vent, which communicates with the outside atmospheric pressure, is located in a different part of the housing that allows X-rays to pass through (transmissive). An air passageway connects the bladder's interior to this remote vent, ensuring the bladder is still exposed to atmospheric pressure despite its shielded location.

• Claim 14: An X-ray tube with a radiation-shielded bladder and a remote, semi-permeable vent.
  This claim outlines an X-ray tube with an outer housing containing a coolant and a radiation shielding layer on a portion of the housing. An evacuated enclosure is within the housing, in contact with the coolant. The invention centers on a "remote bladder venting system" comprising an expansion bladder situated within the radiation-shielded part of the outer housing. A semi-permeable membrane, which permits atmospheric pressure access, is positioned in a section of the outer housing without the radiation shielding. An air passage connects the bladder to this membrane, allowing the bladder's interior to be subjected to atmospheric pressure.

CAFC 2026 Dockets:
A search for US patent 7,302,042 within the CAFC 2026 dockets using general search tools did not yield any specific results for ongoing litigation or related proceedings for the year 2026. It's important to note that the patent's legal status is "Expired - Fee Related" as of November 27, 2015, due to non-payment of maintenance fees, making active litigation in 2026 highly unlikely.

As of April 26, 2026, no known litigation specifically involving US patent 7302042 has been found through public records. The searches conducted did not return any cases listing this patent number as being litigated in federal courts, including the U.S. Court of Appeals for the Federal Circuit (CAFC) or through the Public Access to Court Electronic Records (PACER) system.

Proceedings overview

There are no AIA trial proceedings on file for US Patent 7,302,042 as of the most recent ingest from the USPTO ODP API. A web search also did not surface any PTAB activity. This means the patent's claims are currently untested by IPR, PGR, or CBM proceedings.

Strategic summary

As there are no PTAB proceedings on file for US Patent 7,302,042, all 20 claims of the patent remain untested by AIA trial challenges. This means there is no estoppel landscape established by prior PTAB decisions, and all prior art grounds (§ 102 / § 103) are theoretically available for a potential petitioner.

The absence of PTAB challenges suggests a few possibilities: either the patent has not been extensively asserted, or previous assertions have not motivated defendants to file IPRs, or the patent has been strategically held back from assertion in contexts where PTAB challenges are common. For a potential defendant, this represents an open field for an AIA trial challenge if they identify strong prior art grounds.

Recommended next steps

Since no PTAB activity exists for US Patent 7,302,042, a defendant currently facing assertion of this patent should consider the following:

1. Prior Art Search: Conduct a thorough prior art search to identify any strong grounds for invalidating the claims under 35 U.S.C. §§ 102 or 103.
2. Evaluate Claims: Analyze the asserted claims in light of the discovered prior art and assess the likelihood of success in an IPR petition.
3. Timing Consideration: If a decision is made to pursue an IPR, consider the statutory deadlines for filing (e.g., within one year of being served with a complaint alleging infringement).
4. Absence as a Signal: While the absence of PTAB challenges is not determinative of validity, it means that the patent owner has not had to defend these claims against the scrutiny of an AIA trial, which can be a rigorous process.

Inventors

• Wayne Rollins Hansen (employed by Varian Medical Systems Technologies Inc. at the time of filing)
• Ricky Smith (employed by Varian Medical Systems Technologies Inc. at the time of filing)

It is a common practice for employee-inventors to assign their rights to their employer, especially when the invention relates to their work for the company and is developed using company resources. There is no indication of the inventors departing the original assignee within 12 months of filing.

Original assignee

The entity named on the issued patent is Varian Medical Systems Technologies Inc. This entity was later absorbed by Varian Medical Systems, Inc.

Varian Medical Systems, Inc. is a leading global manufacturer of medical devices and software for treating cancer and other medical conditions, including X-ray imaging components and systems. The patent describes an X-ray tube, which is a core product area for Varian Medical Systems.

Varian Medical Systems, Inc. was acquired by Siemens Healthineers in April 2021 and now operates as a subsidiary, retaining its headquarters and employees. Therefore, its current status is an operating subsidiary.

Assignment timeline

• 2006-04-17 (executed) / recorded 2006-04-28 — Reel 017550/0775
  • Conveyance: Assignment
  • Assignor: Hansen, Wayne Rollins; Smith, Ricky
  • Assignee: Varian Medical Systems Technologies, Inc.
  • Correspondent: BLAKELY SOKOLOFF TAYLOR & ZAFMAN LLP, 12400 WILSHIRE BLVD. 7TH FLOOR, LOS ANGELES, CALIFORNIA 90025-1026
  • Context: Original assignment from inventors to their employer.
• 2008-09-26 (executed) / recorded 2008-10-13 — Reel 021669/0848
  • Conveyance: Merger
  • Assignor: VARIAN MEDICAL SYSTEMS TECHNOLOGIES, INC.
  • Assignee: VARIAN MEDICAL SYSTEMS, INC.
  • Correspondent: VARIAN MEDICAL SYSTEMS, INC., LEGAL DEPT. M/S H0970, 3100 HANSEN WAY, PALO ALTO, CALIFORNIA 94304-1030
  • Context: Internal reorganization / merger of Varian Medical Systems Technologies, Inc. into Varian Medical Systems, Inc.

Timeline diagram

timeline
    title Ownership of US 7302042
    2006 : Inventors assigned to Varian Medical Systems Technologies Inc
    2007 : Patent issued
    2008 : Varian Medical Systems Technologies Inc merged into Varian Medical Systems Inc

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The transfers are between Varian entities, which are known operating companies in the medical device sector.
2. Known asserter in the chain — not present. Varian Medical Systems, Inc. and its predecessor are not listed as known NPEs.
3. Repeat correspondent across the chain — not present. The first assignment uses Blakely Sokoloff Taylor & Zafman LLP. The second uses Varian Medical Systems, Inc.'s internal legal department. There is no recurrence of a specific correspondent attorney or firm.
4. Cascading transfers — not present. Only two assignments are recorded, occurring more than two years apart.
5. Pre-litigation transfer — unclear. There is no information provided about any infringement suits involving this patent, so it's impossible to determine if a pre-litigation transfer occurred.
6. Bankruptcy fire-sale — not present. Varian Medical Systems, Inc. was acquired by Siemens Healthineers, not dissolved in bankruptcy.
7. Privateering — not present. The patent remains with an operating company (now a subsidiary of Siemens Healthineers) that develops and sells products in the same field.
8. Defensive aggregator (anti-NPE) — not present. The current owner is Varian Medical Systems, Inc., an operating company.

Verdict

Operating-company assertion
The patent remains with Varian Medical Systems, Inc., which is an operating company (now a subsidiary of Siemens Healthineers) that develops and manufactures X-ray tubes and related medical systems. The assignments recorded (Reel 017550/0775 and 021669/0848) reflect the initial inventor-to-company assignment and a subsequent internal merger, not transfers to a non-practicing entity.

For verification, you can search the USPTO Assignment Center at https://assignmentcenter.uspto.gov/.

The USPTO Patent Public Search tool is a web-based application for searching patents and patent application publications. It offers both basic and advanced search interfaces. For patent numbers, the basic search allows direct entry, but for numbers with six digits or less, leading zeros must be added to make it a seven-digit number (e.g., 123456 becomes 0123456). The advanced search provides full query options and additional filtering capabilities.

Here's an analysis of the most relevant prior art for US Patent 7,302,042, based on the citations within the patent itself:

US Patent 7,302,042: Remote bladder venting and containment system

• Inventors: Wayne Rollins Hansen, Ricky Smith
• Assignee: Varian Medical Systems Inc.
• Filing Date: 2006-04-28
• Publication Date: 2007-11-27
• Abstract: The patent describes a system for remotely venting an expansion bladder in a liquid-filled container, specifically an x-ray tube. The remote venting allows the bladder to be positioned in a radiation-shielded area while the vent itself is in an unshielded area, thus avoiding compromising the shielding. A semi-permeable membrane in the vent prevents liquid escape in case of bladder rupture.

Most Relevant Prior Art Citations:

1. US 6,366,642 B1:

   • Full Citation: US 6,366,642 B1 to Varian Medical Systems, Inc.
   • Publication/Filing Date: 2002-04-02 (Publication Date); 2001-01-16 (Priority Date)
   • Brief Description: This patent describes an X-ray tube cooling system. It is cited as prior art regarding general x-ray tube cooling systems and the challenges of heat dissipation. The patent abstract of US7302042B2 also specifically defines an "x-ray tube" as containing an evacuated enclosure, electron source, and anode, which aligns with the components found in the cooling system described in US6366642B1.
   • Potential Anticipation (35 U.S.C. § 102): US 6,366,642 B1 could potentially anticipate aspects of claims related to the general structure and cooling of an x-ray tube with a cooling liquid and an evacuated enclosure (e.g., elements of claims 1, 8, and 14 related to an "outer housing containing a coolant" and an "evacuated enclosure disposed in the outer housing so as to be at least in partial fluid communication with the coolant"). However, it does not appear to describe the remote venting or containment features that are central to the novelty of US 7,302,042.

2. US 6,529,579 B1:

   • Full Citation: US 6,529,579 B1 to Varian Medical Systems, Inc.
   • Publication/Filing Date: 2003-03-04 (Publication Date); 2000-03-15 (Priority Date)
   • Brief Description: This patent also describes a cooling system for high-power x-ray tubes. Like US 6,366,642 B1, it provides context for existing x-ray tube cooling technologies. The patent's description notes that maintaining consistent liquid pressure in the reservoir (or outer housing) is an important aspect of managing high power x-ray tube cooling.
   • Potential Anticipation (35 U.S.C. § 102): Similar to US 6,366,642 B1, this patent could potentially anticipate the fundamental elements of an x-ray tube cooling system, including an outer housing, coolant, and evacuated enclosure (e.g., elements of claims 1, 8, and 14). However, it does not disclose the specific remote venting and liquid containment mechanism provided by a semi-permeable membrane as claimed in US 7,302,042.

It's important to note that while these patents are cited as prior art, the claims of US 7,302,042 aim to distinguish themselves by introducing the remote bladder venting and containment system (specifically using a semi-permeable membrane to prevent liquid escape and allowing the bladder to be placed in a shielded region). Therefore, direct anticipation under 35 U.S.C. § 102 would require these prior art references to disclose all elements of a given claim. If they do not, an obviousness argument under 35 U.S.C. § 103 might be considered, potentially combining elements from multiple references or general knowledge in the field.

Obviousness Analysis of US Patent 7,302,042 under 35 U.S.C. § 103

This analysis identifies combinations of prior art references that would render the independent claims (Claims 1, 8, and 14) of US Patent 7,302,042 obvious to a person having ordinary skill in the art (PHOSITA). The motivation for combining these references stems directly from problems acknowledged in the background section of US7302042, which a PHOSITA would have been striving to solve.

The problems addressed by US7302042 include:

1. Compromise of radiation shielding in X-ray tubes due to the need for expansion bladders to access atmospheric pressure. Prior art often required a "gap... in the shielding layer" for this purpose, leading to "increased complexity and cost".
2. The risk of "extensive cooling liquid leakage and dispersal from the tube" upon expansion bladder failure, posing "burn risk" and "contamination risk" due to the nature of the cooling liquids used (e.g., dielectric oil).

A PHOSITA would be motivated to address these known challenges in X-ray tube design.

Obviousness of Claim 1: An X-ray tube with a remotely vented bladder in a substantially X-ray transmissive region.

Claim 1 Elements:

• Outer housing containing a coolant.
• Evacuated enclosure disposed in the outer housing and in fluid communication with the coolant, containing an electron source and an anode.
• An expansion bladder contained within the outer housing, defining an interior volume.
• A port defined in the outer housing configured to provide atmospheric pressure access to the bladder's interior via an air passageway.
• Crucially, the port is positioned within a region of the outer housing that is substantially x-ray transmissive.

Prior Art Combination: US6366642B1 in view of the acknowledged problem in US7302042 and general engineering principles.

• US6366642B1 (Varian Medical Systems, Inc.): This patent clearly discloses an X-ray tube with an outer housing filled with a dielectric coolant, an evacuated envelope, and an "expansion bladder 40... provided to compensate for changes in the volume of the dielectric coolant as it heats and cools." It also states that the "bladder 40 includes an opening to the ambient environment to allow air to enter and exit the bladder, thereby compensating for coolant volume changes." Furthermore, US6366642B1 explicitly mentions "lead shielding (not shown)" in the housing, indicating its known presence in such X-ray tubes. US6529579B1 similarly describes an X-ray tube with a bladder for pressure equalization and atmospheric access, and mentions radiation shielding.

• Motivation for Combination: The background of US7302042 itself highlights the problem: "a gap must often be made in the shielding layer in order to enable a portion of the bladder to be exposed to the atmosphere," resulting in "increased complexity and cost for the x-ray tube design." A PHOSITA, aware of the need to maintain atmospheric pressure for the bladder (as taught by US6366642B1) and the critical importance of radiation shielding, would be motivated to find a way to vent the bladder without compromising the shielding.

• Obviousness Argument: Given the recognized problem, it would have been obvious for a PHOSITA to relocate the atmospheric access point for the bladder. Instead of requiring a gap in the essential radiation shielding (often located around the X-ray generation area), a PHOSITA would naturally place the vent in a region of the outer housing already known to be "substantially x-ray transmissive" or unshielded (e.g., areas not subject to significant x-ray impingement, as described in US7302042). Connecting the bladder, which is within the housing, to this remotely located vent via a conventional "air passageway" (e.g., a flexible tube or conduit, a common engineering solution for fluid communication) would be a straightforward engineering design choice to solve the stated problem without undue experimentation.

Obviousness of Claim 8: A remote expansion bladder venting system for an X-ray tube with separated shielded and unshielded components.

Claim 8 Elements:

• Expansion bladder positioned within a first region of an X-ray tube housing, the first region being substantially non-transmissive to x-rays (i.e., shielded).
• A vent provided in a second region of the X-ray tube housing, the second region being substantially transmissive to x-rays (i.e., unshielded), the vent in communication with atmospheric pressure.
• An air passageway interconnecting the bladder's interior with the vent.

Prior Art Combination: US6366642B1 (or US6529579B1) in view of the acknowledged problem in US7302042 and general knowledge of X-ray tube construction.

• Prior Art: As established for Claim 1, US6366642B1 teaches an X-ray tube with an expansion bladder requiring atmospheric access and a housing incorporating radiation shielding. A PHOSITA would also possess general knowledge of X-ray tube construction, understanding that certain regions of the housing are purposefully shielded (non-transmissive to X-rays) to contain radiation, while others are unshielded or designed to be X-ray transmissive (e.g., the output window area, or areas generally not subject to significant x-ray impingement). US7302042 itself describes this: "the shielding 32 is positioned on only an upper portion of the x-ray tube 10, as this portion is subject to substantial x-ray impingement. In contrast, the lower portion of the x-ray tube 10 receives less x-ray impingement, and is therefore left unshielded, and thus is more transmissive to x-rays."

• Motivation for Combination: The motivation remains the same as for Claim 1: to avoid "perforat[ing] the radiation shielded portion of the outer housing in order to provide atmospheric pressure to the bladder." A PHOSITA would seek a solution that preserves shielding integrity and simplifies manufacturing.

• Obviousness Argument: It would have been obvious for a PHOSITA to locate the expansion bladder (whose placement might be dictated by thermal or volumetric considerations) within an existing "substantially non-transmissive to x-rays" region of the housing and then to route its necessary atmospheric connection to a conveniently available "substantially transmissive to x-rays" region of the housing via an "air passageway." This direct solution addresses the problem of shielding compromise by utilizing existing structural characteristics of the X-ray tube housing and common fluid connection techniques.

Obviousness of Claim 14: An X-ray tube with a radiation-shielded bladder and a remote, semi-permeable vent.

Claim 14 Elements:

• Outer housing containing a coolant.
• Radiation shielding layer on a portion of the outer housing.
• Evacuated enclosure in communication with the coolant.
• A remote bladder venting system, comprising:
  • An expansion bladder contained within the radiation-shielded portion of the outer housing.
  • A semi-permeable membrane in communication with and substantially transmissive of atmospheric pressure, positioned proximate a portion of the outer housing that does not include the radiation shielding layer.
  • An air passage extending between the expansion bladder and the semi-permeable membrane.

Prior Art Combination: US6366642B1 (or US6529579B1) combined with the explicit problems in US7302042 and general knowledge of semi-permeable membranes.

• Prior Art (Core System): The combination for Claims 1 and 8 already establishes the X-ray tube with an expansion bladder within a radiation-shielded portion of the housing, and a remote atmospheric vent in an unshielded portion, connected by an air passage.

• Motivation for Adding Semi-permeable Membrane: The background of US7302042 explicitly details the severe problem of "extensive cooling liquid leakage and dispersal from the tube" if the expansion bladder fails, posing "burn risk" and "contamination risk" from the often hot and caustic dielectric oils used as coolants. A PHOSITA would be highly motivated to prevent such hazardous leakage while maintaining atmospheric pressure access.

• Known Solutions (Semi-permeable Membranes): The patent itself acknowledges the existence of "GORE™ membrane vents by W.L. Gore & Associates, Inc." and describes them as "microporous, expanded PTFE membrane that is naturally hydrophobic and oleophobic to repel water and oil, while still being permissive to the passage of air, other gases, and vapors therethrough." This demonstrates that semi-permeable membranes with the precise properties required (allowing air/gas but preventing liquid passage) were known and commercially available to a PHOSITA at the time of the invention.

• Obviousness Argument: Given the established need for a remote vent (to preserve shielding) and the critical problem of liquid leakage upon bladder failure, it would have been obvious for a PHOSITA to incorporate a known semi-permeable membrane (such as a GORE™ membrane) into the remote air passage or at the vent port. This straightforward integration of a commercially available component, known for its ability to selectively permit gas passage while blocking liquid, directly addresses the recognized safety and containment problem without affecting the bladder's ability to equalize pressure.

Therefore, the combinations of US6366642B1 (or US6529579B1) with the problems identified in the background of US7302042 and general engineering knowledge, including the availability of semi-permeable membranes, would render independent claims 1, 8, and 14 of US7302042 obvious to a person having ordinary skill in the art.