Obviousness

Obviousness Analysis of US Patent 8,013,568 under 35 U.S.C. § 103

This analysis of US patent 8,013,568 considers what would have been obvious to a person having ordinary skill in the art (PHOSITA) at the time of the invention's priority date (July 29, 2005), based solely on the prior art acknowledged within the patent's "BACKGROUND ART" section.

Level of Ordinary Skill in the Art:
A person having ordinary skill in the art pertinent to US 8,013,568 would likely be an electrical engineer or technician with expertise in power electronics, battery management systems, inductive power transfer, and wireless communication. Such a person would understand electromagnetic induction principles, circuit design for power conversion (rectifiers, constant voltage/current suppliers), feedback control systems, and basic wireless data communication techniques, including methods for mitigating electromagnetic interference.

Acknowledged Prior Art (from US8013568 BACKGROUND ART):

1. Conventional Contact-Based Charging Systems: Batteries for personal portable devices often have exposed contact terminals, which are susceptible to contamination, wear, and corrosion, leading to poor electrical contact and potential short circuits.
2. Conventional Contact-less Charging Systems (Prior Art A - e.g., FIGS. 1 & 2): These systems use electromagnetic induction for wireless power transfer.
   • Charger (e.g., Charger 10): Includes a high-frequency power driving unit (e.g., 30) that receives power from an AC source (e.g., 20) and applies a high-frequency AC current to a primary coil (e.g., 40) to generate a magnetic field.
   • Battery (e.g., Battery 50): Includes a secondary coil (e.g., 70) where a high-frequency AC current is induced, a rectifier (e.g., 80) to convert this to DC, and a constant voltage/constant current (CV/CC) supplier (e.g., 90) to charge a battery cell (e.g., 60).
   • Acknowledged Problem: The intensity of the induced AC current in the secondary coil is proportional to the magnetic flux, which varies with the relative position of the primary and secondary coils. If the battery is positioned where a strong magnetic field is induced, an overvoltage exceeding the standards of the CV/CC supplier can occur, potentially damaging internal parts.
   • Prior Art Solution to Overvoltage: Mechanically fixing the relative positions of the charger and battery (e.g., grooves 130, 140 and protrusions 150, 160 for an electric toothbrush 100 and charger 120 in FIG. 2).
   • Identified Deficiency of Prior Art Solution: This mechanical restriction causes user inconvenience, as the user must precisely align the devices. The stated objective of US8013568 is to overcome this restriction while preventing damage.

General Knowledge of the Art (Implicit in the patent's background):

• Feedback Control Systems (Prior Art B): It is a fundamental principle in electrical engineering to monitor an output parameter (e.g., voltage or current) and use that information to adjust an input parameter (e.g., power supply output) to maintain a desired operating state or prevent component damage.
• Wireless Communication (Prior Art C): Wireless data transmission between electronic devices was a well-established technology by 2005 for various purposes, including control signals.
• Electromagnetic Interference (EMI) Mitigation (Prior Art D): The potential for interference between high-power electromagnetic fields (used for charging) and low-power wireless communication signals (for data) is a known issue. Time-division multiplexing, where power transfer and data communication occur in alternating time slots, is a recognized method for mitigating such interference. The patent itself explicitly mentions that "If an adjustment request signal is wirelessly transmitted while a magnetic field is generated... the adjustment request signal may be screened due to the magnetic field and thus the adjustment request signal may not be properly received". This demonstrates that a PHOSITA would be aware of this problem.

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Obviousness Combinations:

A PHOSITA would be motivated to combine these prior art elements to address the acknowledged problems in conventional contact-less charging systems, specifically the "inconvenience" of rigid positional requirements while ensuring protection against overvoltage.

Combination 1: Conventional Inductive Charging with Wireless Feedback Control for Power Adjustment (Rendering Claims 1 and 13 Obvious)

• Combination of References: Prior Art A (conventional contact-less charging system with overvoltage problem) + Prior Art B (feedback control principles) + Prior Art C (wireless communication).

• Motivation: The conventional contact-less charging system (Prior Art A) is known to suffer from overvoltage issues at the CV/CC supplier when relative coil positions vary, which the patent explicitly highlights as causing "inconvenience" due to mechanical fixation. A PHOSITA, aiming to eliminate this inconvenience while retaining overvoltage protection, would naturally consider implementing a dynamic adjustment mechanism. Applying fundamental feedback control principles (Prior Art B) to regulate the charging power output by the charger, based on the operating conditions of the battery's CV/CC supplier, is a logical step. Given that the power transfer itself is wireless, extending the feedback loop to be wireless (using Prior Art C) would be an obvious design choice to maintain the "contact-less" nature and enhance user convenience by removing physical contact requirements for feedback.

  • For Claim 1 (Contact-less Chargeable Battery): The elements of a high-frequency AC current inducing unit, rectifier, and CV/CC supplier are explicitly present in the conventional battery (e.g., 50) of Prior Art A. Monitoring voltages at "both ends of the constant voltage/constant current supplier" to detect an overvoltage condition is a standard diagnostic technique for protecting sensitive components, directly motivated by the known overvoltage problem in Prior Art A. Transmitting this "monitoring result" (which could be a simple "overvoltage detected" signal, voltage values, or an adjustment request as detailed in claims 5 and 6) wirelessly to the charging device (using Prior Art C) would be an obvious means for the battery to communicate its state in a contact-less manner, enabling the charger to "induce a change of intensity of the magnetic field" (via power adjustment, Prior Art B) to alleviate the overvoltage.

  • For Claim 13 (Contact-less Charging Device): The magnetic field generating unit (primary coil) and high-frequency power driving unit are clearly taught by the conventional charger (e.g., 10) in Prior Art A. A "charging power adjusting unit" that "receives the monitoring result from the contact-less chargeable battery by means of wireless communication" (using Prior Art C) and "controls the high frequency power driving unit to adjust a power" (using Prior Art B) would be an obvious counterpart to the battery's wireless transmission mechanism. The motivation is to dynamically respond to the battery's condition to prevent overvoltage and allow for flexible positioning, directly addressing the stated "inconvenience" of Prior Art A.

Combination 2: Wireless Feedback Control with Intermittent Operation for Reliable Communication (Rendering Claims 21 and 23 Obvious)

• Combination of References: Combination 1 (Wireless Feedback Control) + Prior Art D (EMI mitigation techniques).

• Motivation: Once the PHOSITA designs a wireless feedback control system (as in Combination 1), they would immediately encounter the challenge of electromagnetic interference between the high-frequency power transfer and the wireless data communication. The patent itself identifies this problem, stating that the wireless communication signal "may be screened due to the magnetic field" generated by the primary coil. A well-known solution for enabling reliable data communication in environments with strong electromagnetic fields is to separate the high-power transmission and low-power data communication in time (Prior Art D). Therefore, a PHOSITA would be motivated to "intermittently apply a high frequency AC current" from the charger and for the battery to "transmit a monitoring result... while a high frequency AC current is not induced in the secondary coil" (i.e., during the pause periods). This time-division multiplexing would ensure that the feedback signal is reliably received by the charging device, thereby enhancing the overall functionality and reliability of the wireless feedback charging system.

  • For Claim 21 (Battery Charging Set): This claim explicitly includes both the intermittent generation of the magnetic field from the charger and the transmission of the monitoring result from the battery "while a high frequency AC current is not induced." This directly reflects the combination of the wireless feedback system with standard EMI mitigation techniques (Prior Art D) to ensure robust communication, which a PHOSITA would find obvious given the recognized interference problem.

  • For Claim 23 (Method): The steps of "intermittently applying a high frequency AC current to a primary coil" (step a) and "transmitting a monitoring result... while a high frequency AC current is not induced in the secondary coil" (step e) directly illustrate the time-division multiplexing approach (Prior Art D) to ensure reliable wireless feedback communication in an inductive charging environment. The remaining steps (b, c, d, f) represent the known inductive charging process and the feedback control mechanism, as made obvious by Combination 1.

In conclusion, the core elements of US patent 8,013,568 – a contact-less battery system with an overvoltage monitoring unit, wireless communication of this monitoring result to a charging device, and the charging device's subsequent adjustment of charging power, including the optimization of intermittent operation for communication – would have been obvious to a PHOSITA at the time of invention. The motivation would be to overcome the acknowledged "inconvenience" of rigid mechanical positioning in prior art contact-less charging systems while maintaining critical overvoltage protection, utilizing well-known engineering principles of feedback control, wireless communication, and EMI mitigation.