Proximity sensor and proximity detection method

• US 20090051355A1
• Filed: 08/31/2006
• Published: 02/26/2009
• Est. Priority Date: 09/02/2005
• Status: Abandoned Application

• Current Assignee: Azuma Systems Company Limited
• Original Assignee: Azuma Systems Company Limited
• Inventors: Yamakawa, Kazuhiro
• Application Number:
  US11/991,156
• Publication Number:
  US 20090051355A1
• Time in Patent Office: Days
• US Class Current: 324/207.260
• CPC Class Codes: H03K 17/954 controlled by an oscillatory signal
• CPC Class Codes: H03K 17/9547 with variable amplitude

Abstract

A proximity sensor for detecting proximity of a metal, wherein a driving signal is output to a resonant circuit that includes a capacitor connected to a detecting coil, and the proximity of the metal is detected based on a phase shift of freely oscillating waves that are attenuatedly output from the resonant circuit after an output of the driving signal is stopped, the proximity sensor includes a controller that outputs the driving signal to the resonant circuit; and measures a phase shift of oscillating waves that is involved in the proximity of the metal based on the freely oscillating waves that are attenuatedly output from the resonant circuit after the output of the driving signal is stopped.

Claims

1. A proximity sensor for detecting proximity of a metal, wherein a driving signal is output to a resonant circuit that includes a capacitor connected to a detecting coil, and the proximity of the metal is detected based on a phase shift of freely oscillating waves that are attenuatedly output from the resonant circuit after an output of the driving signal is stopped, the proximity sensor comprising:

a controller that;

outputs the driving signal to the resonant circuit; and

measures a phase shift of oscillating waves that is involved in the proximity of the metal based on the freely oscillating waves that are attenuatedly output from the resonant circuit after the output of the driving signal is stopped.

3. The proximity sensor according to claim 1, wherein the controller:

counts a number of the freely oscillating waves that are attenuatedly output from the resonant circuit after the output of the driving signal is stopped; and

counts a time until a predetermined number of the freely oscillating waves are counted.

4. The proximity sensor according to claim 1, wherein the controller:

repeats a predetermined number of times a regression operation of counting a number of the freely oscillating waves that are output from the resonant circuit after the output of the driving signal is stopped, and outputting the driving signal at a time of counting a predetermined number of the freely oscillating waves, so that the phase shift of the freely oscillating waves is amplified.

5. The proximity sensor according to claim 1, wherein the controller:

repeats a predetermined number of times a regression operation of counting a number of the freely oscillating waves that are output from the resonant circuit after the output of the driving signal is stopped, and outputting the driving signal at a time of counting the predetermined number of the freely oscillating waves, so that the phase shift of the freely oscillating waves is amplified;

starts clocking in response to a first output of the driving signal; and

finishes clocking when a predetermined number of the freely oscillating waves is output from the resonant circuit after the regression operation is finished the predetermined number of times.

19. The proximity sensor according to claim 1, wherein the detecting coil is also used as an exciting coil.

22. The proximity sensor according to claim 3, wherein the number of the freely oscillating waves is set to about 2 to 100.

25. The proximity sensor according to claim 1, wherein resonant circuit is a series resonant circuit where the capacitor is serially connected to the detecting coil.

2. (canceled)

6-11. -11. (canceled)

12. A proximity detecting method for detecting proximity of a metal, the proximity detecting method comprising:

outputting a driving signal to a resonant circuit that includes a capacitor connected to a detecting coil; and

detecting the proximity of the metal based on a phase shift of freely oscillating waves that are attenuatedly output from the resonant circuit after the output of the driving signal is stopped.

13. The proximity detecting method according to claim 12, further comprising the steps of:

outputting the driving signal to the resonant circuit;

counting a number of the freely oscillating waves that are attenuatedly output from the resonant circuit after the output of the driving signal is stopped;

measuring a time until a predetermined number of the freely oscillating waves is counted; and

measuring the phase shift of the oscillating waves that is involved in the proximity of the metal based on the measured time.

20. The proximity detecting method according to claim 12, wherein the detecting coil is also used as an exciting coil.

23. The proximity detecting method according to claim 13, wherein the number of the freely oscillating waves is set to about 2 to 100.

26. The proximity detecting method according to claim 12, wherein resonant circuit is a series resonant circuit where the capacitor is serially connected to the detecting coil.

14. A proximity detecting method for detecting proximity of the metal, the proximity detecting method comprising:

outputting a driving signal to a resonant circuit that includes a capacitor connected to a detecting coil;

measuring a phase shift of oscillating waves that is involved in the proximity of the metal based on freely oscillating waves that are attenuatedly output from the resonant circuit after the output of the driving signal is stopped; and

repeating a predetermined number of times a regression operation of counting a number of the freely oscillating waves that are output from the resonant circuit after the output of the driving signal is stopped, and outputting the driving signal to the resonant circuit at a time of counting a predetermined number of the freely oscillating waves, so that the phase shift of the freely oscillating waves is amplified.

15. The proximity detecting method according to claim 14, further comprising the steps of:

starting clocking in response to a first output of the driving signal to the resonant circuit;

finishing clocking when the predetermined number of the freely oscillating waves is output from the resonant circuit after the regression operation is finished the predetermined number of times; and

measuring the phase shift of the oscillating waves that is involved in the proximity of the metal based on a result of the clocking.

21. The proximity detecting method according to claim 14, wherein the detecting coil is also used as an exciting coil.

24. The proximity detecting method according to claim 14, wherein the number of the freely oscillating waves is set to about 2 to 100.

27. The proximity detecting method according to claim 14, wherein resonant circuit is a series resonant circuit where the capacitor is serially connected to the detecting coil.

16-18. -18. (canceled)