Pen

1. A pen comprising:

an electrode;

a power supply circuit which, in operation, supplies a first voltage;

a first integrated circuit coupled to the power supply circuit, wherein the first integrated circuit, in operation, outputs a transmission signal at the first voltage;

a second integrated circuit including a level shifter which, in operation, outputs the transmission signal at a second voltage that is higher than the first voltage;

an inter-integrated circuit wire which, in operation, supplies the transmission signal having the first voltage from the first integrated circuit to the second integrated circuit;

an electrode wire which, in operation, supplies the transmission signal having the second voltage from the second integrated circuit to the electrode; and

a step-up circuit coupled to the power supply circuit, wherein the step-up circuit, in operation, supplies the second voltage to the level shifter,

wherein the second integrated circuit further includes:

an Rx terminal which, in operation, outputs a reception signal received by the electrode;

a Tx terminal which, in operation, receives the transmission signal, and

a switch which, in operation, switches a destination to which the electrode wire is coupled between the Rx terminal and the Tx terminal,

wherein the inter-integrated circuit wire includes:

an inter-integrated circuit Rx wire coupled to the Rx terminal, and

an inter-integrated circuit Tx wire coupled to the Tx terminal,

wherein the inter-integrated circuit Rx wire and the inter-integrated circuit Tx wire are provided independently of each other,

wherein the electrode wire, in operation, is shared between the transmission signal and the reception signal,

wherein the electrode includes:

a first electrode provided at a tip of the pen, and

a second electrode having a ring shape,

wherein the electrode wire includes:

a first electrode wire coupled to the first electrode, and

a second electrode wire coupled to the second electrode,

wherein the Tx terminal includes:

a first Tx terminal corresponding to the first electrode, and

a second Tx terminal corresponding to the second electrode,

wherein the inter-integrated circuit Tx wire includes:

a first inter-integrated circuit Tx wire coupled to the first Tx terminal, and

a second inter-integrated circuit Tx wire coupled to the second Tx terminal, and

wherein the Rx terminal and the inter-integrated circuit Rx wire are provided commonly for the first electrode and the second electrode.

2. The pen according to claim 1 ,

wherein the step-up circuit includes an external coil provided outside the first integrated circuit and the second integrated circuit and wherein the external coil, in operation, is controlled by a first control signal supplied from the first integrated circuit.

3. The pen according to claim 2 ,

wherein the step-up circuit includes the external coil and a circuit provided in the second integrated circuit.

4. The pen according to claim 2 ,

wherein the step-up circuit, in operation, generates the second voltage by performing on/off control of a current that flows through the external coil.

5. The pen according to claim 1 ,

wherein the switch includes an Rx guard circuit which, in operation, prevents the transmission signal from flowing into the Rx terminal.

6. The pen according to claim 5 ,

wherein the Rx guard circuit, in operation, sets a potential of a wire coupled to the Rx terminal to a predetermined potential.

7. The pen according to claim 1 ,

wherein, in an initial state of the switch, the electrode wire is coupled to the Rx terminal.

8. The pen according to claim 1 ,

wherein the switch, in operation, withstands the second voltage.

9. The pen according to claim 8 ,

wherein the switch, in operation, withstands a voltage of 10 volts.

10. The pen according to claim 1 ,

wherein the second integrated circuit includes a merging circuit which, in operation, couples the first electrode wire and the second electrode wire to the Rx terminal at a time of reception of the reception signal.

11. The pen according to claim 1 ,

wherein the switch, in operation, is controlled by a second control signal supplied from the first integrated circuit.

12. The pen according to claim 1 ,

wherein the first integrated circuit includes a reception amplifier which, in operation, amplifies the reception signal.

13. The pen according to claim 1 ,

wherein the pen operates in a reflective mode that causes a position detection device to detect the pen by transmitting, from the first electrode or the second electrode, a second signal obtained by inverting a phase of a first signal received by the first electrode or the second electrode.

14. The pen according to claim 13 ,

wherein the second signal is transmitted at a timing based on a reception timing of the first signal.

15. The pen according to claim 14 ,

wherein a potential of the Rx terminal is fixed to a predetermined reference potential at the timing based on the reception timing of the first signal.