Stylus Signal Phase Calibration via Dynamic Timing Adjustment
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Solution Overview
Problem
Existing stylus-digitizer systems face challenges in maintaining accurate phase alignment of signal transmissions due to variable delays in wireless communication channels, which can lead to signal cancellation and increased complexity in receiver circuits.
Innovation Solution
A control loop circuit and method that dynamically adjusts transmission timings in the stylus to compensate for delays in both receiving and transmitting circuits, using calibration procedures initiated by tip-down events and repeated periodically, and a digitizer system that monitors signal strength to instruct the stylus to adjust its timing for optimal alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase alignment is maintained using fixed timing in stylus-digitizer systems, then initial synchronization can be achieved, but variable delays in wireless communication channels cause signal cancellation and detection accuracy degradation
Solution Approach 1:
The patent implements dynamic timing adjustment where the stylus controller continuously modifies transmission timing based on feedback from the digitizer. The system transitions from fixed timing to adaptive timing that responds to channel conditions, using a control loop that measures signal strength and adjusts timing accordingly to maintain optimal phase alignment despite variable delays
Solution Approach 2:
The patent employs a feedback mechanism where the digitizer measures the strength of received stylus signals and communicates this information back to the stylus controller. The controller uses this feedback to dynamically adjust transmission timing, creating a closed-loop system that continuously optimizes phase alignment and prevents signal cancellation
2Measurement precision
If complex phase matching components are added to each receiving circuit to maintain phase alignment, then signal detection accuracy improves, but device complexity and circuit cost increase
Solution Approach 1:
The patent replaces complex hardware-based phase matching components with a software/firmware-based timing adjustment mechanism. Instead of using additional analog phase shifters or complex circuitry in the receiver, the system uses digital timing control in the stylus transmitter, substituting mechanical/electrical phase adjustment with temporal scheduling
Solution Approach 2:
The patent introduces a timing control mechanism as an intermediary between the stylus transmitter and digitizer receiver. Rather than modifying the receiver circuitry to handle phase variations, the timing control acts as a mediator that pre-adjusts transmission timing to compensate for expected delays, simplifying the receiver design
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AI summary
A method includes receiving by wireless transmission, a first signal transmitted by a digitizer system. The first signal is configured to define a detection period during which a second signal may be detected by the digitizer system. The method further includes detecting timing of the receiving, detecting a first delay in the receiving due to amplification associated with the receiving, defining timing to transmit the second signal based on the timing of the receiving and the first delay and transmitting the second signal at the timing defined. The second signal is transmitted with a handheld device by wireless transmission and the first delay is detected by the handheld device that is receiving the first signal and transmitting the second signal.