Position detection system for detection object and position detection method for detection object

A position detection system for a detection object, comprising:

• a magnetic-field generating unit including a position-detection-signal generating section that generates an alternating signal of predetermined frequency and a position-detection-magnetic-field generating section that generates a position-detection magnetic field based on the alternating signal;
• a detection object including a coil and a capacitor constituting a resonant circuit and an internal-signal switch that connects or disconnects the path of the resonant circuit based on an internal signal, the detection object generating a resonant magnetic field by causing resonance when a current flows through the resonant circuit in response to the position-detection magnetic field;
• a switch-controlling unit disposed inside the detection object and including a switching-signal generating section that generates a switching signal for controlling connecting or disconnecting of the internal-signal switch;
• a position-detection-magnetic-field detecting unit that detects the magnetic field strength of the position-detection magnetic field and the resonant magnetic field;
• a position-calculating unit that calculates the position and orientation of the detection object based on a detection signal from the position-detection-magnetic-field detecting unit;
• a switching-signal extracting unit that extracts the switching signal by detecting a level change of the detection signal;
• a memory that stores the detection signal from the position-detection-magnetic-field detecting unit;
• and
• a position-detection controlling unit that stores the detection signal from the position-detection-magnetic-field detecting unit in the memory separately divided into a detection signal resulting from detection of the position-detection magnetic field alone and a detection signal resulting from detection of the position-detection magnetic field and the resonant magnetic field.

A position detection method for detecting the position of a detection object including a coil and a capacitor constituting a resonant circuit and an external-signal switch that connects or disconnects the path of the resonant circuit based on a switching signal, the detection object generating a resonant magnetic field by causing resonance when a current flows through the resonant circuit in response to the position-detection magnetic field, the method comprising:

• generating the switching signal for controlling connecting or disconnecting of the external-signal switch from a switching-signal generating section of a switch-controlling unit disposed outside the detection object and transmitting the switching signal to the external-signal switch by converting the switching signal into physical energy in a switching-signal transmitting section;
• generating an alternating signal of predetermined frequency from a position-detection-signal generating section of a magnetic-field generating unit and generating a position-detection magnetic field based on the alternating signal from a position-detection-magnetic-field generating section;
• detecting the magnetic field strength of the position-detection magnetic field and the resonant magnetic field in a position-detection-magnetic-field detecting unit;
• calculating the position and orientation of the detection object based on a detection signal detected by the position-detection-magnetic-field detecting unit in a position-calculating unit;
• and
• storing the detection signal detected by the position-detection-magnetic-field detecting unit in a memory separately divided into a detection signal resulting from detection of the position-detection magnetic field alone and a detection signal resulting from detection of the position-detection magnetic field and the resonant magnetic field.

A position detection method for detecting the position of a detection object including a coil and a capacitor constituting a resonant circuit and an internal-signal switch that connects or disconnects the path of the resonant circuit based on a switching signal, the detection object generating a resonant magnetic field by causing resonance when a current flows through the resonant circuit in response to the position-detection magnetic field, the method comprising:

• generating the switching signal for controlling connecting or disconnecting of the internal-signal switch from a switching-signal generating section of a switch-controlling unit disposed inside the detection object;
• generating an alternating signal of predetermined frequency from a position-detection-signal generating section of a magnetic-field generating unit and generating a position-detection magnetic field based on the alternating signal from a position-detection-magnetic-field generating section;
• detecting the magnetic field strength of the position-detection magnetic field and the resonant magnetic field in a position-detection-magnetic-field detecting unit;
• calculating the position and orientation of the detection object based on a detection signal detected by the position-detection-magnetic-field detecting unit in a position-calculating unit;
• extracting the switching signal by detecting a level change of the detection signal in a switching-signal extracting unit;
• and
• storing the detection signal detected by the position-detection-magnetic-field detecting unit in a memory separately divided into a detection signal resulting from detection of the position-detection magnetic field alone and a detection signal resulting from detection of the position-detection magnetic field and the resonant magnetic field.