Active Pen Carrier Frequency Division for Multi-Pen Time Slots
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Solution Overview
Problem
Existing technologies have not effectively addressed the need for simultaneous input with multiple active pens, leading to complex computation and inefficient time utilization due to differing symbol durations and unused times in time slots.
Innovation Solution
Implementing an active pen and sensor integrated circuit capable of avoiding complex computation for phase acquisition, which are also capable of generating carrier waves for the downlink signals using a simple configuration, namely, a frequency dividing circuit, and are further capable of reducing the difference in unused time in one time slot between active pens.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If frequency dividing circuit is used to generate carrier waves at different frequencies, then device complexity is reduced, but computation complexity for phase acquisition increases
Solution Approach 1:
The patent changes the parameter of symbol duration from frequency-dependent to fixed by introducing a virtual frequency concept. The sensor integrated circuit calculates symbol duration based on a virtual frequency (e.g., 500 kHz) rather than the actual transmission frequency, making symbol duration a constant parameter independent of the actual carrier frequency. This resolves the contradiction by maintaining simple frequency division while enabling uniform phase acquisition computation.
2Adaptability or versatility
If different frequencies are used for multiple active pens, then simultaneous transmission is enabled, but unused time difference between pens increases
Solution Approach 1:
The patent introduces a virtual frequency parameter to standardize the symbol duration across all active pens. By calculating symbol duration based on a common virtual frequency rather than individual transmission frequencies, all pens transmit for the same duration within a time slot, eliminating unused time and enabling full utilization of the time slot for simultaneous multi-pen transmission.
Data Source
AI summary
A system includes a sensor integrated circuit and an active pen. The active pen is for communication with the sensor integrated circuit. The active pen includes a frequency dividing circuit which, in operation, controls generating a first carrier wave having a first frequency selected from a plurality of frequencies orthogonal to each other. The active pen includes a transmission circuit which, in operation, controls transmitting a first downlink signal directed to the sensor integrated circuit, by modulating the first carrier wave with a value of a first symbol, which is a transmission target, in a symbol duration that is common among the plurality of frequencies.