Obviousness

The US patent 10108277 aims to solve problems associated with conventional electrostatic coupling position detection apparatuses, specifically their inability to detect information beyond a pointer's position (e.g., pressure, pen down status, rotational position, inclination) or to simultaneously detect multiple types of pointers, such as a pen and a finger. The invention proposes using codes with correlation matching operations to transmit and detect this additional information.

A person having ordinary skill in the art (POSITA) in the field of pointing devices and signal processing, as of the priority date of February 5, 2010, would have been motivated to combine existing electrostatic coupling position detection technology with established signal processing and data encoding techniques to overcome the identified limitations.

Combination of Prior Art References and Motivation for Combination:

1. Japanese Patent Laid-Open No. H8-50535 (or similar conventional electrostatic coupling position detector) + General Knowledge of Encoding and Decoding Information using Codes and Correlation Matching:
   • Prior Art 1: Japanese Patent Laid-Open No. H8-50535 is explicitly cited in US10108277 as an example of a conventional electrostatic coupling position detection apparatus that can detect the pointer's position. This reference establishes the baseline technology for electrostatic position sensing.
   • General Knowledge: By the priority date, methods for embedding various types of information into electrical signals and extracting that information using code-based correlation matching were well-known in communication and signal processing. The patent itself mentions the use of "spread codes including an M sequence, a gold code sequence or the like or orthogonal codes such as, for example, the Hadamard code or the Walsh code" and states that "identification sensitivity of code patterns can be increased based on a correlation matching operation process upon reception". This indicates that these code types and the benefits of correlation matching were part of common technical knowledge.
   • Motivation to Combine: A POSITA, recognizing the limitations of basic electrostatic position detectors as described in the background of US10108277, would be motivated to enhance these systems to provide richer user input. The objective would be to transmit additional data (e.g., pressure, pen down, pointer type) without significantly altering the fundamental electrostatic coupling mechanism.
     • Pressure Detection: Integrating a variable capacitor (or similar pressure-sensitive element, such as a variable inductor or resistor) whose capacitance changes with pen pressure with a code production circuit that varies the time difference between two transmitted codes based on this capacitance would be an obvious design choice. By transmitting these two codes (which can be the same or different patterns) and detecting the time difference between their correlation peaks at the receiver, the pressure could be derived. This directly applies known methods of time-encoding information to the electrostatic signal.
     • Pen Down/Hovering Detection: Using a mechanical switch linked to the pen tip (e.g., switch 101 in FIG. 11) to switch between transmitting a first code (pen down) and a second code (hovering) would be an obvious way to signal the pen's state. The position detector could then use correlation matching to identify which code is received, thereby determining the pen's state.
     • Side Switch Detection: Similarly, signaling the activation of a side switch (e.g., side switch 113 in FIG. 12A) by inverting a code signal or transmitting a distinct third code from a separate electrode piece would be a straightforward application of encoding device state information.
     • Rotational Position and Inclination Detection: Employing multiple electrically divided electrode pieces on the pointer (e.g., 211a, 211b, 211c, 211d in FIG. 19) and supplying different codes or time-shifted codes to these pieces would be an obvious extension. By analyzing the differential reception signal levels of these codes across multiple reception conductors (e.g., X1, X2, X3, Y1, Y2, Y3), the pointer's rotational position and inclination could be deduced. This leverages the spatial distribution of encoded signals to infer orientation.
     • Simultaneous Multi-Pointer Detection (Pen and Finger): For a POSITA, distinguishing between different input types like a pen and a finger on the same surface would suggest employing distinct identifiers. Transmitting unique spread codes for a pen (e.g., C1, C2) and for touch input (e.g., C3 from the position detector's own spread code production section 231) and using correlation matching to identify these codes would be an obvious approach. Alternatively, implementing time-division multiplexing to alternately enable pen tablet and touch panel functions (as shown in FIG. 23) represents a known method for handling multiple input modes on a shared sensing surface.
     • Modulation Techniques (PSK, FSK): The patent notes that "Predetermined modulation may be applied to spread codes" and specifically describes PSK (Phase Shift Keying) and FSK (Frequency Shift Keying) modulation. These are well-known techniques in communication systems for improving signal-to-noise ratio, increasing frequency range, and reducing detection errors. Applying such known modulation schemes to the transmitted codes would be an obvious engineering choice for a POSITA aiming to enhance the robustness and accuracy of the communication link between the pointer and the detector.

Conclusion:
The claims of US10108277, which involve extending the functionality of an electrostatic coupling position detection apparatus to include detection of pressure, pen down, side switch operations, rotational position, inclination, and simultaneous multi-pointer detection, would be obvious to a POSITA. This is because the underlying mechanisms for achieving these additional functionalities—namely, encoding information into signals via time differences, distinct code patterns, spatial distribution, or modulation, and then decoding this information using correlation matching—were well-established signal processing and communication techniques by the priority date. Combining these known techniques with a conventional electrostatic position detection system (such as that described in Japanese Patent Laid-Open No. H8-50535) to address the known limitations of such systems would constitute an obvious combination of known elements to achieve predictable results.