POSITION INDICATOR

• US 20120146958A1
• Filed: 01/07/2011
• Published: 06/14/2012
• Est. Priority Date: 12/14/2010
• Status: Active Grant

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Wacom Co Limited (Wacom)
• Inventors: Oda, Yasuo, Yagi, Masaki
• Granted Patent: US 8,199,132 B1
• Time in Patent Office: Days
• US Class Current: 345/179
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/0441 using active external devices, e.g. active pens, for receiving changes in electrical potential transmitted by the digitiser, e.g. tablet driving signals
• CPC Class Codes: G06F 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A position indicator is provided for use with a position detecting sensor that carries out position detection by detecting a change in capacitance. The position indicator includes: a first electrode configured to receive an alternating-current (AC) signal from the position detecting sensor; a signal enhancing processing circuit configured to subject the AC signal received via the first electrode to determined signal enhancing processing; and a second electrode different from the first electrode and configured to be supplied with a signal output from the signal enhancing processing circuit. An enhanced signal having a determined correlation with the AC signal received via the first electrode from the position detecting sensor is formed while the enhanced signal is sent out to the position detecting sensor via the second electrode.

Claims

1. A position indicator for use in conjunction with a position detecting sensor that carries out position detection by detecting a change in capacitance, the position indicator comprising:

a first electrode configured to receive an alternating-current (AC) signal from the position detecting sensor;

a signal enhancing processing circuit configured to subject the AC signal received via the first electrode to determined signal enhancing processing; and

a second electrode different from the first electrode and configured to be supplied with an enhanced signal output from the signal enhancing processing circuit;

wherein the first electrode and the second electrode are both disposed at the same end section of the position indicator,

wherein the enhanced signal having a determined correlation with the AC signal received via the first electrode from the position detecting sensor is formed while the enhanced signal is sent out to the position detecting sensor via the second electrode, and

wherein the signal enhancing processing circuit generates the enhanced signal having a signal level higher than a signal level of the AC signal received via the first electrode.

3. The position indicator according to claim 1, characterized in that:

the signal level of the enhanced signal generated by the signal enhancing processing circuit is increased in at least one of a region of a rising edge of a waveform of the enhanced signal and a region of a falling edge of the waveform of the enhanced signal.

4. The position indicator according to claim 1, characterized in that:

the enhanced signal generated by the signal enhancing processing circuit results from performing determined phase control on the AC signal received via the first electrode.

5. The position indicator according to claim 4, characterized in that:

the determined phase control is compensation for a phase of the AC signal received via the first electrode.

6. The position indicator according to claim 1, characterized in that:

the signal enhancing processing circuit subjects a signal waveform of the AC signal received via the first electrode to waveform conversion.

7. The position indicator according to claim 6, characterized in that:

the signal enhancing processing circuit converts the signal waveform of the AC signal received via the first electrode into a rectangular waveform.

8. The position indicator according to claim 1, characterized in that:

the signal enhancing processing circuit includes a variable signal amplification factor circuit configured to control a signal level of the AC signal received via the first electrode.

9. The position indicator according to claim 8, characterized in that:

the variable signal amplification factor circuit is an automatic gain adjusting circuit configured to output a signal having a constant signal level against variations in the signal level of the AC signal received via the first electrode.

10. The position indicator according to claim 9, characterized in that:

the variable signal amplification factor circuit is a manually variable amplification factor circuit configured to increase the signal level of the AC signal received via the first electrode with a determined amplification factor.

11. The position indicator according to claim 1, characterized in that:

a shielding member is disposed between the first electrode and the second electrode for preventing electrical interference therebetween.

12. The position indicator according to claim 11, characterized in that:

the shielding member surrounds at least one electrode of the first electrode and the second electrode, and is electrically grounded.

13. The position indicator according to claim 11, characterized in that:

the position indicator has a shape of a stylus and the second electrode is disposed so as to surround the first electrode, and the shielding member surrounds the first electrode and is disposed between the first electrode and the second electrode.

14. The position indicator according to claim 13, characterized in that:

one end section of the shielding member is disposed so as to project from the second electrode in a longitudinal direction of the position indicator, and a collar section is formed at the one end section.

15. The position indicator according to claim 1, characterized by further comprising a connection changing circuit configured to switch the first electrode and the second electrode with each other as an electrode for signal reception and an electrode for signal transmission.

2. (canceled)