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US 10,296,039 B2Granted
Analog circuit, position indicator, and system
AssigneeWacom Co., Ltd.
InventorsYuji Katsurahira, Takeshi Koike, Hideyuki Hara
Life of this patent
Estimating the term…
Abstract
A low-power-consumption, noise-immune analog circuit for a position indicator is provided. The analog circuit provided by the present disclosure is connected to an electrode that receives a control signal by capacitive coupling, and includes an edge detection circuit and a waveform restoration circuit. The edge detection circuit detects rising and falling edges of the control signal received by the electrode. The waveform restoration circuit restores the waveform of the control signal in accordance with the rising and falling edges detected by the edge detection circuit.
Claims10
A position indicator comprising:
- an electrode that receives a control signal by capacitive coupling;
- and
- a receiver circuit that decodes the control signal received by the electrode;
- wherein
- the receiver circuit includes
- a) an edge detection circuit that detects rising and falling edges of the control signal received by the electrode, the edge detection circuit including:
- a differential circuit that receives, as an input, the control signal received by the electrode, and detects the rising and falling edges in accordance with an output signal of the differential circuit,
- a positive direction pulse detection circuit that detects the rising edge in accordance with the output signal of the differential circuit, the positive direction pulse detection circuit including a first comparator,
- a negative direction pulse detection circuit that detects the falling edge in accordance with the output signal of the differential circuit, the negative direction pulse detection circuit including a second comparator, and
- a waveform restoration circuit that restores the waveform of the control signal in accordance with the output signals of the first and second comparators, wherein the waveform restoration circuit includes a latch circuit that keeps generating high-level outputs after when the output signal of the first comparator rises until when the output of the second comparator rises, and keeps generating low-level outputs after when the output signal of the second comparator rises until when the output of the first comparator rises;
- and
- b) a decoding circuit that decodes the control signal in accordance with the waveform restored by the waveform restoration circuit.
9 more elements
A system comprising:
- a tablet;
- and
- a position indicator;
- wherein
- the tablet includes
- a sensor controller that generates a control signal in accordance with a command indicative of an instruction for the position indicator, and
- a first electrode that transmits the control signal;
- the position indicator includes
- a second electrode that receives the control signal by capacitive coupling with the first electrode, and
- a receiver circuit that decodes the control signal received by the second electrode;
- and
- the receiver circuit includes
- a) an edge detection circuit that detects rising and falling edges of the control signal received by the second electrode, the edge detection circuit including:
- a differential circuit that receives, as an input, the control signal received by the electrode, and detects the rising and falling edges in accordance with an output signal of the differential circuit,
- a positive direction pulse detection circuit that detects the rising edge in accordance with the output signal of the differential circuit, the positive direction pulse detection circuit including a first comparator,
- a negative direction pulse detection circuit that detects the falling edge in accordance with the output signal of the differential circuit, the negative direction pulse detection circuit including a second comparator, and
- a waveform restoration circuit that restores the waveform of the control signal in accordance with the output signals of the first and second comparators, wherein the waveform restoration circuit includes a latch circuit that keeps generating high-level outputs after when the output signal of the first comparator rises until when the output of the second comparator rises, and keeps generating low-level outputs after when the output signal of the second comparator rises until when the output of the first comparator rises;
- and
- b) a decoding circuit that decodes the control signal in accordance with the waveform restored by the waveform restoration circuit.
16 more elements
Dependencies are inferred from the claim text.