US 2015/0145836 A1 · CAPACITIVE STYLUS PEN

Abstract

A capacitive stylus pen is provided that inputs an indicated position to a tablet by capacitive coupling. The capacitive stylus pen includes a signal generating circuit that generates a signal having the same frequency as a frequency of a signal to be transmitted from an electrode, a transformer that boosts the generated signal and that includes a primary winding and a secondary winding, and an analog switch for controlling connection between a first end of the secondary winding and the electrode to an on-state or an off-state. The capacitive stylus pen further includes a power extracting circuit that extracts power to be supplied to the analog switch from an electromotive force induced in the secondary winding, and a capacitor coupled to a second end of the secondary winding to set the second end at a fixed potential in an alternating-current manner.

Claims20

Dependent claims

A capacitive stylus pen, comprising:

an electrode configured to transmit a first signal, the electrode being positioned at a position indicating part of the capacitive stylus pen;
a signal generating circuit configured to generate a second signal, the second signal having a frequency that is substantially the same as a frequency of the first signal;
a transformer configured to boost the second signal, the transformer including a primary winding and a secondary winding that are wound around a magnetic body;
an analog switch configured to set the electrode to an on-state and an off-state by control of a connection between a first end of the secondary winding and the electrode;
a power extracting circuit configured to extract power to be supplied to the analog switch from the secondary winding;
and
a capacitor configured to set a second end of the secondary winding to a fixed potential in an alternating-current manner, the capacitor being coupled to the second end.

4 more elements

Dependencies are inferred from the claim text.

Capacitive stylus pen

Life of this patent

Capacitive stylus pen

Life of this patent

Abstract

Claims20