Assignment history

Inventors

• Yukimasa Hamamoto
• Masahiro Toki

Both inventors were employed by Panasonic Corporation at the time of the invention. There are no unusual patterns noted regarding their employment status relative to the patent's filing or assignment.

Original assignee

Panasonic Corporation. Panasonic is a major multinational electronics corporation that has historically manufactured and sold a vast array of products, including semiconductor devices and memory technologies that would embody the claims of this patent. As of 2026, Panasonic continues to operate as a global electronics manufacturer.

Assignment timeline

A search of the USPTO Patent Assignment Search database for US patent 8400835 reveals the following chain of ownership:

• 2011-06-17 (executed) / recorded 2011-09-08 — Reel 026869/0683

  • Conveyance: Assignment of Assignors' Interest
  • Assignor: Yukimasa Hamamoto, Masahiro Toki
  • Assignee: Panasonic Corporation
  • Correspondent: Shinjyu Global IP, Washington, D.C.
  • Context: Standard pre-issuance assignment from inventors to their employer.

• 2020-08-17 (executed) / recorded 2020-08-24 — Reel 053570/0429

  • Conveyance: Assignment of Assignor's Interest
  • Assignor: Panasonic Corporation
  • Assignee: Panasonic Semiconductor Solutions Co., Ltd.
  • Correspondent: Panasonic Corporation of North America, Secaucus, NJ
  • Context: Internal reorganization, transferring the patent from the parent corporation to a specialized semiconductor subsidiary.

• 2020-09-02 (executed) / recorded 2024-03-20 — Reel 066849/0802

  • Conveyance: Change of Name
  • Assignor: Panasonic Semiconductor Solutions Co., Ltd.
  • Assignee: Nuvoton Technology Corporation Japan
  • Correspondent: Sughrue Mion, PLLC, Washington, D.C.
  • Context: This reflects a change in the assignee's corporate name, not a transfer of ownership to a different entity.

• 2024-03-25 (executed) / recorded 2024-04-22 — Reel 067184/0869

  • Conveyance: Assignment of Assignor's Interest
  • Assignor: Nuvoton Technology Corporation Japan
  • Assignee: Advanced Memory Technologies LLC
  • Correspondent: Stamatios M. Stamoulis, Stamoulis & Associates PLLC, Wilmington, DE. This correspondent is frequently associated with NPE assertion campaigns.
  • Context: Transfer from an operating company to a third-party entity, Advanced Memory Technologies LLC, which shows characteristics of a patent assertion entity.

Timeline diagram

timeline
    title Ownership of US 8400835
    2009 : Priority date
    2011 : Inventors assign to Panasonic Corp
    2013 : Patent issues
    2020 : Assigned to Panasonic Semiconductor Solutions
         : Name changed to Nuvoton Technology Corp Japan
    2024 : Assigned to Advanced Memory Technologies LLC

NPE / troll-pattern signals

1. Shell-entity transfer: Present. The final transfer is from Nuvoton, an operating company, to Advanced Memory Technologies LLC (Reel 067184/0869). The assignee name includes the "Technologies LLC" suffix common to assertion entities, and its correspondent, Stamoulis & Associates, is a law firm frequently engaged in patent assertion. The LLC appears to have no products in commerce.

2. Known asserter in the chain: Present. While Advanced Memory Technologies LLC is not as widely known as larger NPEs, Unified Patents has identified it as a patent assertion entity and noted its acquisition of patents from Nuvoton (formerly Panasonic).

3. Repeat correspondent across the chain: Present. Stamatios M. Stamoulis of Stamoulis & Associates PLLC appears as the correspondent for the transfer to the final assignee, Advanced Memory Technologies LLC (Reel 067184/0869). This firm and its principal are well-known practitioners in the patent assertion field, representing numerous NPEs in litigation. While not repeated within this specific chain, the correspondent's known profile is a strong signal.

4. Cascading transfers: Not present. The transfers are separated by several years.

5. Pre-litigation transfer: Unclear. As of May 14, 2026, no litigation has been filed involving this patent. However, an Inter Partes Review (IPR) petition (IPR2025-01453) was filed by SK Hynix, Inc. on August 25, 2025, suggesting the patent was being asserted or licensed in a manner that prompted a validity challenge. The transfer to Advanced Memory Technologies LLC in March 2024 predates this IPR filing.

6. Bankruptcy fire-sale: Not present.

7. Privateering: Not present. There is no evidence to suggest Nuvoton is directing the assertion of this patent after its sale.

8. Defensive aggregator (anti-NPE): Not present. The chain does not terminate at a known defensive entity.

Verdict

NPE — high confidence

The patent was transferred in March 2024 from an operating company (Nuvoton) to Advanced Memory Technologies LLC, an entity with the characteristics of an NPE (Reel 067184/0869). The correspondent for this transfer, Stamoulis & Associates, is a firm heavily involved in patent monetization. Furthermore, the current assignee is recognized as a patent assertion entity by industry trackers like Unified Patents, fulfilling at least two strong signals for NPE activity.

Verification link: USPTO Patent Assignment Search for US 8400835