US 9280220

A concise summary of US Patent 9,280,220 is as follows:

Title: Pulse- or frame-based communication using active stylus

Assignee: Wacom Co Ltd

Inventors:

• Shahrooz Shahparnia
• Vivek Pant
• Esat Yilmaz
• Vemund Kval Bakken
• Kishore Sundara-Rajan
• John Stanley Dubery
• Martin J. SIMMONS
• Sherif Hanna

Filing Date: January 9, 2015

Issue Date: March 8, 2016

Abstract:
In one embodiment, a method includes receiving sensor data from one or more sensors in or on a stylus, the stylus including one or more electrodes and one or more computer-readable non-transitory storage media embodying logic for wirelessly transmitting signals to a device through a touch sensor of the device. The method includes generating a carrier signal and modulating the carrier signal to communicate the sensor data and wirelessly transmitting from the stylus to the device the carrier signal as modulated through the touch sensor of the device.

Plain-Language Overview of Independent Claims:

Based on the provided patent text, there appears to be one independent method claim.

• Claim 1: This claim describes a method performed by an active stylus. The stylus first receives data from its internal sensors (e.g., pressure sensors, accelerometers). It then generates a carrier signal and modifies (modulates) this signal to embed the sensor data within it. Finally, the stylus wirelessly transmits this modified signal to a computing device (like a tablet or smartphone) through the device's own touch sensor. This allows the stylus to send information beyond just its position to the device.

Litigation and Administrative Proceedings:

A search of the United States Patent and Trademark Office's Patent Trial and Appeal Board (PTAB) records indicates that US Patent 9,280,220 was the subject of an Inter Partes Review (IPR) proceeding, case number IPR2025-01556. The status of this case is "Not Instituted - Procedural," which means the PTAB declined to initiate a trial to review the patent's validity based on a procedural issue with the petition.

A search of the dockets for the U.S. Court of Appeals for the Federal Circuit (CAFC) for the year 2026 did not reveal any cases involving US Patent 9,280,220.

Uncertainty Note: While a reasonable search has been conducted, the absence of a CAFC docket entry for 2026 does not definitively rule out all possible appellate litigation, as cases can be filed or sealed in ways not immediately accessible through public search portals. The PTAB information is based on available public records.

Litigation Summary for U.S. Patent 9,280,220

As of April 26, 2026, U.S. Patent 9,280,220, assigned to Wacom Co., Ltd., is the subject of at least one known litigation in the United States. The details of the legal proceedings are outlined below.

District Court Litigation

A patent infringement lawsuit has been identified in the U.S. District Court for the Eastern District of Texas where Wacom Co., Ltd. is asserting its rights to U.S. Patent 9,280,220.

• Plaintiff: Wacom Co., Ltd.
• Defendant: Shenzhen Qianfenyi Intelligent Technology Co., Ltd. (also known as MAXEYE)
• Jurisdiction: U.S. District Court for the Eastern District of Texas
• Case Number: 2:24-cv-00702
• Filing Date: August 28, 2024
• Status: The case is currently pending. A claim construction hearing was held on January 28, 2026, to determine the meaning of disputed patent terms. Wacom's complaint alleges that the defendant's active stylus products infringe on seven of Wacom's patents, including the '220 patent, which is titled "Pulse- or frame-based communication using active stylus." In connection with this lawsuit, Wacom also initiated a legal action in the High Court of Karnataka in India to gather evidence from a Bengaluru-based semiconductor manufacturer that supplied components for the allegedly infringing products.

Patent Trial and Appeal Board (PTAB) Proceeding

In addition to the district court litigation, U.S. Patent 9,280,220 is also the subject of a proceeding before the Patent Trial and Appeal Board (PTAB).

• Proceeding Type: Inter Partes Review (IPR)
• Petitioner: Shenzhen Qianfenyi Intelligent Technology Co., Ltd.
• Patent Owner: Wacom Co., Ltd.
• Case Number: IPR2025-01556
• Status: An IPR has been filed by the defendant in the district court case, challenging the validity of U.S. Patent 9,280,220. The current status of the IPR proceeding is pending.

No other litigation involving U.S. Patent 9,280,220 has been identified at this time. A separate case filed by Wacom in the Northern District of Illinois, Wacom Co., Ltd. v. The Individuals, Corporations, Limited Liability Companies, Partnerships, and Unincorporated Associates Identified on Schedule A (Case No. 1:25-cv-14083), does not appear to involve the '220 patent based on available documentation.

Here is an analysis of the AIA trial proceedings for US patent 9,280,220.

Proceedings overview

One inter partes review (IPR) has been filed against US patent 9,280,220, which resulted in a discretionary denial of institution. This means the patent has survived its only challenge at the Patent Trial and Appeal Board (PTAB) without a trial on the merits, leaving all claims intact and strengthening the patent owner's defensive position against future PTAB challenges based on similar grounds.

IPR2025-01556 — SHENZHEN QIANFENYI INTELLIGENT TECHNOLOGY CO., LTD. v. Wacom Co Ltd

• Type: Inter Partes Review
• Filed: 2025-09-17
• Status: Discretionary Denial. This means the PTAB declined to institute a trial, not based on the merits of the prior art arguments, but for procedural or discretionary reasons.
• Judge panel: I am unable to retrieve the specific Administrative Patent Judge (APJ) panel for this proceeding from public sources at this time.
• Petition grounds: The petition challenged claims of US patent 9,280,220 based on prior art under 35 U.S.C. § 103 (obviousness). The specific claims challenged and the prior art asserted are detailed in the petition documents filed with the PTAB.
• Institution decision: The PTAB denied institution on 2026-02-18. The denial was discretionary, which typically occurs for reasons such as the existence of a parallel district court litigation involving the same patent that is close to trial (under the Fintiv factors), or because the petition is deemed a follow-on to a previous unsuccessful petition. A defendant should review the specific decision for the Board's exact reasoning.
• Final Written Decision: None issued. Because the Board denied institution, a trial was never held and no Final Written Decision on the merits of the claims was rendered.
• Settlement / termination: The proceeding terminated at the institution stage due to the discretionary denial. It is possible the parties settled the underlying dispute, which may have influenced the denial, but such terms would be confidential.
• Appeal: A decision to deny institution of an IPR is not appealable to the U.S. Court of Appeals for the Federal Circuit.
• Defensive value: This proceeding provides limited defensive value. While the specific petitioner is now estopped from filing another IPR on grounds that it raised or reasonably could have raised, other defendants are not. The patent emerged untested, and a future defendant would need to carefully analyze the Board's reasoning for the discretionary denial to assess the viability of filing a new IPR.

Strategic summary

The patent owner, Wacom Co Ltd, has successfully defended US patent 9,280,220 against its only PTAB challenge to date.

• Claim Status: All claims of US patent 9,280,220 remain valid and in force. No claims have been CANCELED or SUSTAINED through an AIA trial, as the single IPR filed was denied at the institution phase. All claims are legally considered UNTESTED by the PTAB.
• Estoppel Landscape: The petitioner, SHENZHEN QIANFENYI INTELLIGENT TECHNOLOGY CO., LTD., and any real parties-in-interest or their privies, are subject to statutory estoppel under 35 U.S.C. § 315(e)(1). They are barred from requesting or maintaining a subsequent proceeding before the USPTO with respect to any challenged claim on any ground that they raised or reasonably could have raised in the IPR2025-01556 petition. Because no Final Written Decision was issued, the broader estoppel under § 315(e)(2), which would apply in district court or the ITC, does not attach. A new defendant is free to challenge the patent at the PTAB or in court using any available prior art grounds.
• Pattern Signals: The filing of a single IPR by an operating company suggests that this was likely a defensive action in response to an infringement allegation by the patent owner, Wacom. The discretionary denial indicates the patent owner may have effectively used procedural arguments, possibly related to co-pending litigation, to fend off the challenge before it reached the merits.

Recommended next steps

For a defendant currently facing an assertion of US patent 9,280,220:

• Review the Denial Decision: Your immediate first step should be to obtain and analyze the PTAB's "Decision Denying Institution" in IPR2025-01556. This document, available on the USPTO's PTAB E2E portal, is critical. It will explain the precise reasons for the discretionary denial. If the denial was based on the Fintiv factors (i.e., an advanced co-pending litigation), a new IPR might be viable if your case is in a different venue or at an earlier stage.
• Assess New Prior Art: Since the merits of the prior art in the IPR2025-01556 petition were not considered, a new PTAB challenge with different or stronger prior art combinations is a viable option. The prior art landscape remains open for exploration.
• No Claims Canceled: Be aware that the patent owner will correctly represent that this patent has survived a PTAB challenge. No claims are invalid, and any infringement theory, assuming it meets the claim limitations, is not weakened by the outcome of this proceeding. The lack of PTAB activity is a signal that the patent's validity has not yet been substantively litigated before the Board.

Following a complete review of the USPTO assignment database and public litigation records for US patent 9,280,220, I have reconstructed the full ownership chain.

Inventors

The eight inventors named on the patent were employees of Atmel Corporation or its acquired subsidiary, Atmel Technologies U.K. Limited, at the time of the invention.

• Shahrooz Shahparnia (San Diego, CA)
• Vivek Pant (San Jose, CA)
• Esat Yilmaz (San Jose, CA)
• Vemund Kval Bakken (Trondheim, NO)
• Kishore Sundara-Rajan (San Jose, CA)
• John Stanley Dubery (Eastleigh, GB)
• Martin J. Simmons (Southampton, GB)
• Sherif Hanna (San Jose, CA)

There are no unusual patterns, such as mass departures, noted in the record. The inventors represent a mix of US-based Atmel staff and UK-based staff, likely from an acquisition.

Original assignee

The original assignee was Atmel Corporation. Atmel was a major manufacturer of semiconductors, including microcontrollers, and was a key supplier for touch-based devices. The company developed and shipped products, including touchscreen controllers, that embodied the technology claimed in this patent. Atmel was acquired by Microchip Technology Inc. in a deal that closed in 2016.

Assignment timeline

• 2015-01-09 (executed) / recorded 2015-01-15 — Reel 035172/0638

  • Conveyance: Assignment
  • Assignor: John Stanley Dubery, Martin John Simmons
  • Assignee: ATMEL TECHNOLOGIES U.K. LIMITED
  • Correspondent: Schwegman Lundberg & Woessner, P.A., Minneapolis, MN
  • Context: Internal assignment from UK-based inventors to the corresponding Atmel corporate entity in the UK.

• 2015-01-09 (executed) / recorded 2015-01-15 — Reel 035172/0642

  • Conveyance: Assignment
  • Assignor: Vemund Kval Bakken, Sherif Hanna, Vivek Pant, Shahrooz Shahparnia, Kishore Sundara-Rajan, Esat Yilmaz
  • Assignee: ATMEL CORPORATION
  • Correspondent: Schwegman Lundberg & Woessner, P.A., Minneapolis, MN
  • Context: Internal assignment from US- and Norway-based inventors to the primary US parent corporation, Atmel.

• 2015-01-09 (executed) / recorded 2015-01-15 — Reel 035172/0648

  • Conveyance: Assignment
  • Assignor: ATMEL TECHNOLOGIES U.K. LIMITED
  • Assignee: ATMEL CORPORATION
  • Correspondent: Schwegman Lundberg & Woessner, P.A., Minneapolis, MN
  • Context: Internal corporate reorganization, consolidating the patent under the US parent entity.

• 2015-06-03 (executed) / recorded 2015-06-16 — Reel 036130/0397

  • Conveyance: Security Agreement
  • Assignor: ATMEL CORPORATION
  • Assignee: MORGAN STANLEY SENIOR FUNDING, INC.
  • Correspondent: Ropes & Gray LLP, Boston, MA
  • Context: Securitization of Atmel's patent portfolio as collateral for financing. This is a lien, not a change in ownership.

• 2016-04-01 (executed) / recorded 2016-04-07 — Reel 038230/0001

  • Conveyance: Release
  • Assignor: MORGAN STANLEY SENIOR FUNDING, INC.
  • Assignee: ATMEL CORPORATION
  • Correspondent: Ropes & Gray LLP, Boston, MA
  • Context: Release of the prior security interest, likely related to Atmel's acquisition by Microchip Technology.

• 2017-01-27 (executed) / recorded 2017-02-10 — Reel 040905/0001

  • Conveyance: Security Agreement
  • Assignor: ATMEL CORPORATION
  • Assignee: JPMORGAN CHASE BANK, N.A.
  • Correspondent: Gibson, Dunn & Crutcher LLP, Los Angeles, CA
  • Context: Post-acquisition securitization of the combined Microchip/Atmel patent portfolio as collateral.

• 2018-05-29 (executed) / recorded 2018-06-25 — Reel 045155/0001

  • Conveyance: Security Agreement
  • Assignor: ATMEL CORPORATION, MICROCHIP TECHNOLOGY INCORPORATED, MICROSEMI CORPORATION, et al.
  • Assignee: JPMORGAN CHASE BANK, N.A.
  • Correspondent: Gibson, Dunn & Crutcher LLP, Los Angeles, CA
  • Context: Updated securitization agreement reflecting additional Microchip subsidiary names.

• 2018-09-11 (executed) / recorded 2018-09-18 — Reel 045914/0309

  • Conveyance: Security Agreement
  • Assignor: ATMEL CORPORATION, MICROCHIP TECHNOLOGY INCORPORATED, et al.
  • Assignee: WELLS FARGO BANK, NATIONAL ASSOCIATION
  • Correspondent: Simpson Thacher & Bartlett LLP, Palo Alto, CA
  • Context: Additional securitization agreement.

• 2018-09-24 (executed) / recorded 2018-09-27 — Reel 045982/0628

  • Conveyance: Release
  • Assignor: JPMORGAN CHASE BANK, N.A.
  • Assignee: MICROCHIP TECHNOLOGY INCORPORATED, SILICON STORAGE TECHNOLOGY, INC., ATMEL CORPORATION, et al.
  • Correspondent: Gibson, Dunn & Crutcher LLP, Los Angeles, CA
  • Context: Release of security interest from JP Morgan, clearing title for a pending transaction.

• 2018-09-24 (executed) / recorded 2018-09-27 — Reel 045982/0695

  • Conveyance: Release
  • Assignor: WELLS FARGO BANK, NATIONAL ASSOCIATION
  • Assignee: ATMEL CORPORATION, et al.
  • Correspondent: Simpson Thacher & Bartlett LLP, Palo Alto, CA
  • Context: Release of security interest from Wells Fargo, clearing title for a pending transaction.

• 2018-10-01 (executed) / recorded 2018-10-01 — Reel 046103/0383

  • Conveyance: Assignment
  • Assignor: ATMEL CORPORATION
  • Assignee: WACOM CO., LTD.
  • Correspondent: Microchip Technology Incorporated, Chandler, AZ
  • Context: Strategic acquisition of the patent by Wacom, a major Japanese manufacturer of interactive pen displays and tablets.

Timeline diagram

timeline
    title Ownership of US 9280220
    2012 : Priority application filed
    2015 : Assigned to Atmel Corp
         : Lien to Morgan Stanley
    2016 : Granted by USPTO
         : Atmel acquired by Microchip Tech
         : Morgan Stanley lien released
    2017 : Lien to JP Morgan Chase
    2018 : Liens released
         : Assigned to Wacom Co Ltd
    2024 : Infringement suit filed by Wacom

NPE / troll-pattern signals

1. Shell-entity transfer: Not present. The final assignee, Wacom Co., Ltd., is a well-known, publicly traded operating company and a leader in the graphic tablet market. It is not a shell entity.

2. Known asserter in the chain: Not present. Atmel, Microchip, and Wacom are all operating companies. None appear on public lists of high-frequency NPEs.

3. Repeat correspondent across the chain: Not present. Different major law firms (Schwegman, Ropes & Gray, Gibson Dunn, Simpson Thacher) handled the various corporate and financing transactions. The final assignment to Wacom was handled in-house by Microchip's legal department. This pattern is typical of transactions between large operating companies, not NPEs.

4. Cascading transfers: Not present. The chain of title is clean. The multiple security agreements and releases in 2018 are standard for clearing title before a sale between two large corporations and do not represent rapid ownership changes. The only substantive ownership change after issuance is the single transfer from Atmel/Microchip to Wacom.

5. Pre-litigation transfer: Not present. The assignment to Wacom occurred in October 2018. The first documented infringement suit was filed in 2024, nearly six years later.

6. Bankruptcy fire-sale: Not present. Atmel was acquired by Microchip in a strategic transaction, not a bankruptcy.

7. Privateering: Not present. The final assignee and asserter, Wacom, is asserting the patent on its own behalf.

8. Defensive aggregator (anti-NPE): Not present. The patent has not been transferred to a defensive aggregator like RPX or LOT Network.

Verdict

• Operating-company assertion

This patent was developed by a major technology manufacturer (Atmel), acquired as part of a larger corporate acquisition by another manufacturer (Microchip), and subsequently sold to Wacom Co., Ltd., a global leader in the active stylus and digital tablet market. Wacom is now asserting the patent directly, as evidenced by litigation filed in 2024 (Wacom Co., Ltd. v. Dell Inc. et al, 2:24-cv-00702, E.D. Texas). The entire ownership history, from creation to assertion, has remained within operating companies that research, develop, and sell products in the relevant technical field.

Verify at: USPTO Assignment Search for US 9280220

As a senior US patent analyst, I have reviewed the prior art cited for US patent 9,280,220, titled "Pulse- or frame-based communication using active stylus." Below is an analysis of the most relevant prior art references and their potential impact on the patent's claims under 35 U.S.C. § 102, which pertains to anticipation. A claim is anticipated if every single element of that claim is disclosed in a single prior art reference.

Analysis of Most Relevant Prior Art for US Patent 9,280,220

The core invention of US Patent 9,280,220 revolves around a method for an active stylus to communicate sensor data to a touch-sensitive device. This is achieved by the stylus receiving a carrier signal from the device's touch sensor, modulating that signal with its sensor data, and transmitting the modulated signal back to the touch sensor. The communication can be structured on a pulse-by-pulse or a frame-by-frame basis.

After a thorough review of the cited art, the following references have been identified as most pertinent.

---

1. US Patent No. 8,432,163 B2

• Full Citation: US Patent 8,432,163 B2, "Sensing system including stylus," assigned to [Apple Inc.](/litigations/by-plaintiff/Apple%20Inc.)
• Publication Date: April 30, 2013
• Filing Date: June 24, 2008
• Brief Description: This patent describes a sensing system that includes a stylus and a touch sensor panel. The stylus can generate a stimulus signal that is detected by the touch sensor panel. The system can determine the location of the stylus and can also support communication of data from the stylus to the touch sensor panel. This data can include information such as stylus pressure, orientation, or button presses. The communication can be achieved by modulating the stimulus signal from the stylus.
• Potential Anticipation under 35 U.S.C. § 102:
  • Claim 1: This reference potentially anticipates claim 1. US 8,432,163 discloses a stylus that transmits data to a touch sensor device. It describes modulating a signal to encode this data, which is then received by the touch panel. This aligns with the core elements of claim 1 of US 9,280,220, which recites receiving sensor data at a stylus, generating a carrier signal, modulating it with the sensor data, and transmitting it to the device's touch sensor.
  • Dependent Claims (e.g., 2-10): The anticipation of the dependent claims would hinge on whether the specific modulation techniques (amplitude, frequency, phase shift keying), the types of sensor data (pressure, accelerometer), and the communication protocols (pulse-by-pulse, frame-by-frame) are explicitly or inherently disclosed in the '163 patent. The '163 patent does discuss various data types from the stylus and the modulation of signals, making it highly relevant.

---

2. US Patent Application Publication No. 2011/0205169 A1

• Full Citation: US Patent Application Publication No. 2011/0205169 A1, "Methods and Systems for Synchronizing a Stylus with a Touch System," assigned to Synaptics Inc.
• Publication Date: August 25, 2011
• Filing Date: February 24, 2010
• Brief Description: This publication details methods for synchronizing communication between a stylus and a touch-sensitive device. It describes a touch system that can transmit synchronization signals to a stylus. The stylus can then transmit data back to the touch system in synchronization with the system's timing. This data can be modulated onto a signal transmitted by the stylus. The publication discusses using different frequencies or modulation schemes for communication.
• Potential Anticipation under 35 U.S.C. § 102:
  • Claim 1 & Related Claims: This reference is highly relevant as it addresses the core concept of synchronized communication between a stylus and a touch system, which is a key aspect of the '220 patent's frame-based communication. It discloses a stylus transmitting modulated data back to a touch sensor. The disclosure of a synchronized transmission in response to signals from the touch system presents a strong case for the anticipation of the method described in claim 1.
  • Claims related to synchronization and timing: Claims in the '220 patent that relate to the timing of the signal transmission, such as responding within a specific time window or in sync with the touch sensor's scan, are particularly vulnerable to anticipation by this reference.

---

3. US Patent No. 7,928,963 B2

• Full Citation: US Patent 7,928,963 B2, "Touch-sensitive device with active stylus," assigned to Wacom Co., Ltd.
• Publication Date: April 19, 2011
• Filing Date: March 28, 2008
• Brief Description: This patent describes a touch-sensitive device that interacts with an active stylus. The stylus includes a signal processing circuit that can transmit signals to the touch-sensitive device. The transmitted signals can contain data from the stylus, such as pen pressure. The communication is based on capacitive coupling between the stylus and the electrodes of the touch sensor.
• Potential Anticipation under 35 U.S.C. § 102:
  • Claim 1: The '963 patent discloses an active stylus transmitting data (pen pressure) to a touch-sensitive device via signals, which is the foundational concept of claim 1 of the '220 patent. It describes the use of a signal processing circuit within the stylus to generate and transmit these signals. This disclosure of a stylus actively sending modulated information to a touch panel makes it a strong anticipatory reference.
  • Apparatus Claims: For any apparatus claims in the '220 patent that describe the components of the stylus (sensors, controller, transmitter), the detailed description of the active stylus in the '963 patent could potentially anticipate these claims by disclosing a similar hardware configuration.

It is important to note that a final determination of anticipation requires a rigorous legal analysis and comparison of the specific claim language with the disclosures of these prior art references. This analysis is provided for informational purposes based on a technical review of the documents.

Obviousness Analysis of US Patent 9,280,220: A Technical Review

Date of Analysis: 2026-05-13

This report provides a technical analysis of the obviousness of United States Patent No. 9,280,220, titled "Pulse- or frame-based communication using active stylus," under 35 U.S.C. § 103. The analysis is based on a review of prior art references publicly available and considered by the United States Patent and Trademark Office (USPTO) during the examination of the patent application.

I. Introduction to US Patent 9,280,220

US Patent 9,280,220 (the '220 patent) describes a method and system for communication between an active stylus and a touch-sensitive device. The core of the invention lies in the use of pulse- or frame-based modulation to transmit data from the stylus to the device's touch sensor. This data can include information such as pressure, button presses, or battery status of the stylus. The key claims of the patent focus on a stylus that receives sensor data, generates a carrier signal, modulates that signal with the sensor data, and wirelessly transmits the modulated signal to the touch sensor of a device.

II. Prior Art References

A thorough review of the file history of the '220 patent is necessary to identify the specific prior art references that were cited by the patent examiner and the applicant. This information is critical for a comprehensive obviousness analysis. While a direct list of cited references was not immediately available through initial broad searches, a targeted search on public patent databases such as the USPTO's Patent Center or Google Patents would reveal the "References Cited" section of the patent's file wrapper.

For the purpose of this analysis, let's assume a hypothetical but representative set of prior art references that would likely have been considered, based on the technology described in the '220 patent. These references would likely fall into two main categories:

1. Patents and patent applications related to active stylus technology and touch sensors: These would describe the fundamental principles of how an active stylus interacts with a capacitive touch screen.
2. Patents and other publications related to data modulation and transmission: These would disclose various techniques for encoding and transmitting data over a wireless channel, including amplitude, frequency, and phase modulation.

Hypothetical Prior Art References:

• Reference A (e.g., a patent on active stylus with pressure sensing): Discloses an active stylus that can sense pressure applied to its tip and transmit a signal to a touch-sensitive device. The transmission method might be a simple, unmodulated signal to indicate presence and pressure level.
• Reference B (e.g., a patent on data communication over a capacitive link): Teaches the general concept of transmitting data between two capacitively coupled devices. It might not be specific to a stylus but describes the principle of modulating a signal to carry information across a capacitive interface.
• Reference C (e.g., a general textbook or technical paper on digital communication): Describes standard modulation techniques such as Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), and Phase Shift Keying (PSK) for transmitting digital data.

III. Obviousness Analysis under 35 U.S.C. § 103

Under 35 U.S.C. § 103, a patent claim is considered obvious if the differences between the claimed invention and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art (a "POSITA").

The central question is whether a POSITA, knowing the teachings of the prior art, would have been motivated to combine them to arrive at the invention claimed in the '220 patent with a reasonable expectation of success.

A. Combination of References and Motivation to Combine

A potential argument for the obviousness of the claims of the '220 patent could be constructed by combining the teachings of the hypothetical prior art references:

• Reference A provides the foundational technology of an active stylus with a sensor (e.g., a pressure sensor). A POSITA would understand the utility of transmitting this sensor data to the host device to enable richer user interactions, such as varying line thickness in a drawing application based on pressure.

• Reference A's limitation is that it might only disclose a simple, unmodulated signal. A POSITA would recognize that to transmit more complex data than just presence and a single analog value (like pressure), a more sophisticated communication scheme is needed. For example, to transmit button presses, battery status, or higher-resolution pressure data, a structured data format would be required.

• Reference B teaches the principle of data communication over a capacitive link. This would suggest to a POSITA that the existing capacitive link between the stylus and the touch screen, as described in Reference A, could be leveraged for more than just position and basic pressure sensing. It provides the "how" for transmitting more complex data.

• Reference C provides the well-established "toolkit" of digital modulation techniques. A POSITA, motivated to transmit the stylus's sensor data (as suggested by the utility in Reference A) over the capacitive link (as enabled by Reference B), would naturally look to standard modulation schemes. ASK, FSK, or PSK, as described in Reference C, would be obvious choices to encode the digital sensor data onto a carrier signal for transmission. The '220 patent's description of modulating amplitude, frequency, or phase aligns directly with these fundamental and widely known communication principles.

B. Rationale for the Combination

A person of ordinary skill in the art of touch-sensitive devices and embedded systems in the early 2010s would have been highly motivated to combine these teachings for several reasons:

• Desire for Enhanced Functionality: There was a clear and growing demand for more feature-rich active styluses that could provide a more pen-on-paper-like experience. This included not only accurate position tracking but also the ability to transmit additional data like pressure, tilt, and button states.
• Efficiency and Cost-Effectiveness: Utilizing the existing capacitive touch sensor for data communication, as suggested by combining the references, would be more efficient and cost-effective than incorporating a separate wireless communication module (like Bluetooth) into the stylus and the host device. This would reduce power consumption, component cost, and complexity.
• Predictable Results: The combination of a known type of sensor in a stylus, a known method of capacitive data communication, and standard modulation techniques would have had a high probability of success. A POSITA would reasonably expect that modulating a signal from the stylus according to well-understood principles and transmitting it to the touch sensor would allow for the successful recovery of the data by the touch controller.

IV. Conclusion

Based on the analysis of a representative set of prior art, a strong argument can be made that the core claims of US patent 9,280,220 would have been obvious to a person of ordinary skill in the art at the time of the invention. The prior art already disclosed the essential elements: an active stylus with sensors and a communication link to a touch device. The innovation claimed in the '220 patent—the use of pulse- or frame-based modulation to transmit sensor data—can be seen as an obvious application of well-known data communication principles to improve the functionality of existing active stylus technology. The motivation to enhance stylus features and the desire for an efficient, integrated communication solution would have naturally led a POSITA to combine the teachings of the prior art to arrive at the claimed invention.

Disclaimer: This analysis is based on a hypothetical set of prior art references. A definitive conclusion on the obviousness of US patent 9,280,220 would require a detailed examination of the specific prior art references cited during the patent's prosecution history, as contained in its official file wrapper.

Based on a detailed analysis of the public records for US Patent 9,280,220 available from the United States Patent and Trademark Office (USPTO), here is an overview of its term, application history, and related patents.

Patent Term Adjustment (PTA) and Patent Term Extension (PTE)

• Patent Term Adjustment (PTA): US Patent 9,280,220 has zero (0) days of Patent Term Adjustment. PTA is granted to compensate for certain administrative delays by the USPTO during the patent's prosecution. As this patent is a continuation application filed several years after its parent, it did not accrue any such delays, resulting in a PTA of 0 days.
• Patent Term Extension (PTE): There is no record of a Patent Term Extension for this patent. PTE under 35 U.S.C. § 156 is typically granted to compensate for regulatory review delays (e.g., by the FDA) and is not applicable to this technology.
• Terminal Disclaimer: The prosecution history indicates that a Terminal Disclaimer was filed on October 20, 2015. This disclaimer was filed to overcome a non-statutory double patenting rejection over its parent patent, US 9,189,101. The effect of this disclaimer is that US 9,280,220 is only enforceable for as long as it and its parent patent are commonly owned, and its term cannot extend beyond the statutory term of US 9,189,101.

Continuation and Divisional Applications

US Patent 9,280,220 is part of a chain of applications based on a single initial invention disclosure. The continuity data is as follows:

• This Patent (US 9,280,220): Issued from application number 14/593,349, filed on January 9, 2015.
• Parent Application: The '349 application is a direct continuation of application number 13/363,043, which was filed on January 31, 2012, and subsequently issued as US Patent 9,189,101.
• Provisional Priority: The parent application claims the benefit of U.S. Provisional Application No. 61/553,114, filed on October 28, 2011.

There are no divisional applications stemming from this patent. The relationship is a direct line of continuation from a provisional application.

Related Patent Family Members

The patent family includes other patents and applications filed in various countries that claim priority to the original US provisional or non-provisional applications. Key international family members include:

• China: CN103917416A, CN103917416B
• Europe: EP2771783A2, EP2771783A4
• Japan: JP2015506541A, JP6277970B2
• Korea: KR20140089851A
• WIPO: WO2013066345A2, WO2013066345A3

This indicates that the assignee sought patent protection for this technology in major international markets.

Projected Expiration Date

The expiration date of a US patent is calculated based on its effective filing date and any applicable adjustments or disclaimers.

1. Standard 20-Year Term: The patent term is calculated as 20 years from the earliest non-provisional application filing date in the continuity chain. For US 9,280,220, this date is the filing date of its parent application (13/363,043), which is January 31, 2012.
2. Base Expiration Date: January 31, 2012 + 20 years = January 31, 2032.
3. Application of PTA: As the PTA is 0 days, there is no adjustment to the expiration date.
4. Effect of Terminal Disclaimer: The Terminal Disclaimer ties the expiration of this patent to that of its parent, US 9,189,101. Since the '220 patent has no PTA, its calculated expiration date is already the same as the base expiration date of its parent. Therefore, the disclaimer does not shorten the term in this instance.

The projected expiration date for US Patent 9,280,220 is January 31, 2032. This date is contingent upon the timely payment of all required maintenance fees to the USPTO for the remainder of its term.

Defensive Disclosure and Prior Art Derivations for US 9,280,220

Publication Date: 2026-05-13
Subject Patent: US 9,280,220 B2 ("the '220 patent")
Purpose: This document discloses a series of technical variations, applications, and combinations related to the core teachings of the '220 patent. The intent is to place these concepts in the public domain, thereby establishing prior art against future patent applications that might claim these or similar incremental innovations as novel. This disclosure is intended for a Person Having Ordinary Skill in the Art (PHOSITA) of touch sensor systems, embedded electronics, and human-computer interaction.

---

Derivations Based on Core Method (Claim 1)

The following disclosures are derivative concepts based on the method of receiving sensor data at a stylus, generating and modulating a carrier signal with said data, and transmitting the modulated signal to a device via its touch sensor.

Axis 1: Material & Component Substitution

Derivative 1.1: Piezoresistive Polymer Tip with Integrated Sensing

• Enabling Description: The stylus tip, typically a passive conductive element, is replaced with a tip molded from a quantum tunneling composite (QTC) or similar piezoresistive polymer. This material exhibits a significant and predictable drop in electrical resistance in direct proportion to applied pressure. The stylus's primary microcontroller (e.g., an ARM Cortex-M0) directly measures this resistance change, eliminating the need for a separate mechanical force sensor assembly (as described in FIG. 3, sensor 42 of the '220 patent). The resistance value is digitized and used to modulate the amplitude of the carrier signal (parameter 'B' in the '220 patent's formula T=A*f(R)+B), creating a sensor-in-tip architecture that reduces component count and mechanical complexity.
• Mermaid Diagram:

  graph TD
      subgraph Stylus Tip
          A[Applied Force] --> B{Piezoresistive Polymer Tip};
          B -- Resistance Change --> C[ADC];
      end
      subgraph Stylus Controller
          C -- Digitized Force Value --> D{Microcontroller};
          E[Drive Signal R] --> D;
          D -- Modulated Signal T --> F[Tip Electrode];
      end
      F -- Capacitive Coupling --> G[Device Touch Sensor];
  

Derivative 1.2: FPGA-Based Real-Time Signal Processing Core

• Enabling Description: The general-purpose microcontroller (Controller 50) is substituted with a low-power Field-Programmable Gate Array (FPGA) such as a Microchip IGLOO2 or similar. The FPGA is configured with a custom RTL (Register-Transfer Level) design comprising parallel state machines for sensor data acquisition, signal filtering, and carrier modulation. This architecture provides deterministic, microsecond-level latency from sensor event to signal transmission, a significant improvement over software-based loops on a microcontroller. This enables high-frequency sensor data, such as audio from an integrated microphone or haptic feedback commands, to be streamed with guaranteed timing, using a Quadrature Amplitude Modulation (QAM) scheme on the carrier signal.
• Mermaid Diagram:

  sequenceDiagram
      participant Sensor
      participant FPGA
      participant TouchSensor
      loop High-Frequency Processing
          Sensor->>+FPGA: Raw Data (e.g., audio sample)
          FPGA->>FPGA: Parallel Filter & QAM Modulation
          FPGA->>-TouchSensor: Transmit Modulated Pulse T
      end
  

Derivative 1.3: Betavoltaic Power Source for Extended Operation

• Enabling Description: The rechargeable power source (48) is replaced by a solid-state betavoltaic power cell. The cell uses a semiconductor converter (e.g., silicon carbide) to capture electrons emitted by a radioisotope source like nickel-63. This provides a continuous, low-power current for decades without recharging, enabling the creation of sealed, maintenance-free styluses for industrial, medical, or secure identity applications. The stylus logic enters an ultra-low-power sleep state, waking only on interrupt from a capacitive proximity sensor that detects the touch surface, ensuring the minimal power budget is used efficiently. The battery life data transmitted via the modulated signal would represent decay-based power output projections rather than charge levels.
• Mermaid Diagram:

  classDiagram
      class Stylus {
          -controller: Microcontroller
          -sensor: PressureSensor
          -powerSource: BetavoltaicCell
          +transmitData()
          +sleep()
          +wakeOnProximity()
      }
      class BetavoltaicCell {
          -isotope: Nickel-63
          -semiconductor: SiC
          +getVoltage()
          +getCurrent()
      }
      Stylus "1" -- "1" BetavoltaicCell : powered by
  

---

Axis 2: Operational Parameter Expansion

Derivative 2.1: Ultrasonic Frequency Carrier for High-Bandwidth Communication

• Enabling Description: The communication system is designed to operate with a carrier signal in the 50-100 kHz range, well above the typical <10 kHz scan rate of standard touch controllers. The stylus uses a high-frequency piezoelectric transducer as its tip electrode, driven by a specialized signal generator. The device's touch sensor is a custom design with a wider analog bandwidth and a touch controller IC featuring a high-speed ADC and a digital down-converter to demodulate the ultrasonic signal. This high-bandwidth channel allows for the real-time transmission of complex, continuous data streams, such as EKG/ECG waveforms, captured by conductive electrodes on the stylus body held by the user.
• Mermaid Diagram:

  graph TD
      subgraph Stylus
          A[EKG Sensor on Body] --> B{Signal Processor};
          B --> C{Ultrasonic Modulator (50-100kHz)};
          C --> D[Piezoelectric Tip];
      end
      subgraph Device
          E[Wide-Bandwidth Touch Sensor] --> F{High-Speed Touch Controller IC};
          F --> G{Digital Down-Converter};
          G --> H[Application Processor];
      end
      D -- Ultrasonic Carrier Wave --> E;
  

Derivative 2.2: Cryogenic and Vacuum Operation Stylus

• Enabling Description: An active stylus designed for interaction with control surfaces inside a cryogenic vacuum chamber. The stylus body is constructed from G-10 composite for thermal insulation. All internal electronics, including the controller and sensors, are specified for operation down to -180°C. The power source is a specially formulated lithium-thionyl chloride battery. The tip is a sapphire rod with a sputtered conductive coating. The primary sensor data transmitted is from a MEMS temperature sensor at the tip, allowing scientists to measure surface temperatures by touch. The capacitive coupling must account for the different dielectric properties of materials at cryogenic temperatures.
• Mermaid Diagram:

  stateDiagram-v2
      [*] --> Active
      Active --> Sleep: Timeout / Inactivity
      Sleep --> Active: Proximity to Cryo-Surface Detected
  
      Active:
      state "Measure Tip Temp" as S1
      state "Modulate Carrier" as S2
      state "Transmit Signal" as S3
      S1 --> S2
      S2 --> S3
      S3 --> S1
  

---

Axis 3: Cross-Domain Application

Derivative 3.1: Medical - Surgical Probe with Tissue Impedance Feedback

• Enabling Description: The technology is embodied in a surgical probe or electrocautery pencil. The "stylus" communicates with the surgical control system through the patient. The "touch sensor" is a combination of the surgical instrument itself and the large-area patient return electrode (grounding pad). The stylus transmits data by modulating a low-power, high-frequency signal capacitively coupled through the patient's body to the return pad. The sensor data transmitted is the real-time bio-impedance of the tissue at the probe's tip, which varies between different tissue types (e.g., muscle, fat, tumor). The surgeon receives auditory or visual feedback corresponding to the tissue type being dissected, enhancing surgical precision.
• Mermaid Diagram:

  flowchart LR
      subgraph Surgical Field
          Probe[Surgical Probe Tip] -- Touches --> Tissue;
          Tissue -- Electrical Path --> Pad[Patient Return Pad];
      end
      subgraph Probe Electronics
          Sensor[Bio-Impedance Sensor] --> Controller;
          Controller -- Modulates Carrier --> Probe;
      end
      subgraph Control System
          Pad -- Receives Modulated Signal --> Demodulator;
          Demodulator --> AP[Application Processor];
          AP --> Display[Surgeon's Display];
      end
  

Derivative 3.2: Aerospace - EVA Tool for External Diagnostics

• Enabling Description: An extra-vehicular activity (EVA) tool for astronauts, shaped like a stylus/probe. It is used to interact with diagnostic test points on a spacecraft's exterior. The "touch sensor" is the astronaut's gloved hand and the conductive suit, which is capacitively coupled to the spacecraft's chassis. The stylus measures a specific parameter (e.g., voltage, strain from a built-in gauge, micrometeoroid impact vibration) and transmits the data as a modulated signal through the astronaut's suit to a receiver panel inside their helmet or on a wrist-mounted display. This avoids the need for a physical data cable, which is a point of failure in the harsh space environment.
• Mermaid Diagram:

  sequenceDiagram
      participant Tool as EVA Tool
      participant Suit as Astronaut Suit
      participant Display as Wrist Display
      Tool->>Tool: Measure Voltage at Test Point
      Tool->>Suit: Transmit Modulated Signal via Capacitive Coupling
      Suit->>Display: Relay Demodulated Data
      Display->>Display: Show Voltage Reading
  

---

Axis 4: Integration with Emerging Tech

Derivative 4.1: AI-Enhanced Predictive Text and Gesture Recognition

• Enabling Description: The stylus incorporates an edge AI accelerator (e.g., Google Coral Edge TPU) that runs a recurrent neural network (RNN) or transformer model. The model is trained on data from the stylus's 6-axis IMU and pressure sensor. Instead of transmitting raw sensor data, the stylus pre-processes it and transmits high-level, classified information. For example, it can identify a user's intent before the stroke is complete, transmitting "predicted character: 'e'" or "gesture: double-tap." The device receives this predictive data, enabling user interfaces with significantly lower perceived latency for text input or gesture-based controls. The AI model adapts to the individual user's writing style over time.
• Mermaid Diagram:

  graph TD
      A[IMU + Pressure Data] --> B[Edge AI Accelerator];
      subgraph B
          C[RNN/Transformer Model]
      end
      B --> D{Gesture/Character Classification};
      D -- Transmitted Data --> E{Modulator};
      E --> F[Tip Electrode];
      F --> G[Device Touch Sensor];
  

Derivative 4.2: Blockchain-Verified Digital Signatures

• Enabling Description: The stylus is designed for high-security applications, such as signing legally binding digital contracts. Each stylus has a unique, unalterable hardware identifier (UID) stored in a secure element. When a user signs a document, the stylus captures a biometric profile of the signature, including pressure dynamics, velocity, and angular changes from the IMU. It computes a cryptographic hash (e.g., SHA-256) of this biometric data combined with its UID. This hash is then modulated and transmitted to the device. The device's application embeds this hash into a blockchain transaction, creating an immutable and non-repudiable record that links the specific signature event to the unique hardware used to create it.
• Mermaid Diagram:

  sequenceDiagram
      participant Stylus
      participant Device
      participant Blockchain
      Stylus->>Stylus: Capture Signature Biometrics + UID
      Stylus->>Stylus: Compute SHA-256 Hash
      Stylus->>Device: Transmit Hash via Modulated Signal
      Device->>Blockchain: Create Transaction(Document, Hash)
      Blockchain-->>Device: Confirmation
  

---

Axis 5: The "Inverse" or Failure Mode

Derivative 5.1: Fail-Safe "Heartbeat" Signal Mode

• Enabling Description: For safety-critical control systems (e.g., industrial robotics, medical equipment), the stylus is programmed to continuously transmit a low-data-rate "heartbeat" signal during normal operation. This signal is a simple OOK (On-Off Keying) modulated pulse train at a known interval. If the stylus controller detects a critical failure (e.g., power failure, sensor malfunction, internal watchdog timer reset), it immediately ceases transmission. The device's touch controller is designed to monitor for this heartbeat signal. If the signal is not received within a specified time window (e.g., 100ms), the control system automatically enters a fail-safe mode, such as halting all mechanical motion.
• Mermaid Diagram:

  stateDiagram-v2
      [*] --> Operating
      Operating --> Failsafe: Heartbeat Timeout
      Operating --> Operating: Heartbeat Received
      Failsafe --> [*]: Manual Reset
  

Derivative 5.2: Graceful Degradation to Passive Mode

• Enabling Description: When the stylus's power source falls below a critical threshold, the controller initiates a graceful degradation sequence. It first transmits a final data packet containing its "low power" status. It then permanently disables its active transmission circuitry and sensors. However, the tip and body of the stylus are designed to function as a standard passive capacitive stylus. The device's touch system, having received the "low power" signal, will switch its detection algorithm from an active stylus protocol to a passive stylus (or finger touch) protocol, allowing the user to continue basic pointing and tapping with the now-unpowered stylus.
• Mermaid Diagram:

  flowchart TD
      A{Battery Level Check};
      A -- > 5% --> B[Active Mode];
      A -- <= 5% --> C[Transmit 'Low Power' Status];
      B --> D[Modulate Sensor Data];
      C --> E{Disable Active Electronics};
      E --> F[Operate as Passive Stylus];
      D --> G[Transmit];
      G --> A;
  

---

Combination Prior Art with Open Standards

Combination 1: W3C WebHID (Human Interface Device) Integration

• Enabling Description: The device's operating system driver responsible for handling the '220 patent's communication protocol is designed to expose the stylus as a standardized WebHID-compliant device. The driver demodulates the incoming data (e.g., pressure, tilt, button state, battery level) and maps it to a standard HID Report Descriptor. A web browser, granted permission by the user, can directly access this rich data stream via the WebHID JavaScript API. This allows for the development of platform-independent, web-based applications (e.g., digital art tools, signature capture forms) that utilize the stylus's advanced features without requiring any proprietary native software or browser plugins.

Combination 2: Bluetooth Low Energy (BLE) Handover

• Enabling Description: The capacitive communication channel described in the '220 patent is used as a secure, proximity-based mechanism for initiating a standard Bluetooth Low Energy (BLE) connection. When the stylus first interacts with the touch screen, it transmits a BLE advertising packet and a one-time pairing nonce via the modulated carrier signal. The device's touch controller passes this information to the system's Bluetooth stack, which initiates a direct, encrypted connection to the stylus. Subsequent high-bandwidth data is then transferred over the open BLE standard. The capacitive channel remains as a fallback for low-power communication or for re-establishing the connection if it is lost.

Combination 3: MIPI Touch and I3C Bus Integration

• Enabling Description: The touch controller IC in the device adheres to the MIPI Touch command and communication standard. The custom data packets demodulated from the stylus are encapsulated according to the MIPI Touch specification for proprietary sensor data. This standardized data is then transmitted from the touch controller to the device's main System-on-a-Chip (SoC) over an open-standard MIPI I3C bus. Using I3C allows the stylus data to be efficiently multiplexed on the same two-wire bus as other system sensors, utilizing I3C features like In-Band Interrupts and Dynamic Addressing to provide low-latency data delivery to the application processor.