Position detection device, camera module, and rotary actuator

A position detection device for detecting a position of an object whose position is variable, the position detection device comprising:

• a magnetic field generator that generates a target magnetic field and is configured so that a direction of the target magnetic field at a detection position in a reference plane varies when the position of the object varies;
• and
• a magnetic sensor that detects the target magnetic field and generates a detection signal corresponding to the direction of the target magnetic field, wherein
• the magnetic field generator is configured so that a mode of variation of the direction of the target magnetic field relative to variations in the position of the object varies nonlinearly relative to the variations in the position of the object,
• the magnetic sensor is configured so that a mode of variation of the detection signal relative to variations in the direction of the target magnetic field varies nonlinearly relative to the variations in the direction of the target magnetic field,
• the mode of variation of the direction of the target magnetic field relative to variations in the position of the object and the mode of variation of the detection signal relative to variations in the direction of the target magnetic field are each defined in an orthogonal coordinate system where two parameters are represented by two orthogonal axes,
• a target angle that the direction of the target magnetic field forms with respect to a reference direction in the reference plane varies within a first variable range corresponding to a movable range of the position of the object, and
• the detection signal varies within a second variable range corresponding to the first variable range.

A camera module comprising:

• a lens whose position is variable in a linear direction;
• a position detection device for detecting the position of the lens;
• a holding member that holds the lens;
• and
• a driving device that moves the holding member, wherein
• the position detection device includes a magnetic field generator that generates a target magnetic field and is configured so that a direction of the target magnetic field at a detection position in a reference plane varies as the position of the lens varies, and a magnetic sensor that detects the target magnetic field and generates a detection signal corresponding to the direction of the target magnetic field,
• the magnetic field generator is configured so that a mode of variation of the direction of the target magnetic field relative to variations in the position of the lens varies nonlinearly relative to the variations in the position of the lens,
• the magnetic sensor is configured so that a mode of variation of the detection signal relative to variations in the direction of the target magnetic field varies nonlinearly relative to the variations in the direction of the target magnetic field,
• a target angle that the direction of the target magnetic field forms with respect to a reference direction in the reference plane varies within a first variable range corresponding to a movable range of the position of the lens, and
• the detection signal varies within a second variable range corresponding to the first variable range.

A rotary actuator comprising:

• a rotating body whose position is variable in a direction of rotation about a center axis;
• a position detection device for detecting the position of the rotating body;
• and
• a driving device that rotates the rotating body, wherein
• the position detection device includes a magnetic field generator that generates a target magnetic field and is configured so that a direction of the target magnetic field at a detection position in a reference plane varies as the position of the rotating body varies, and a magnetic sensor that detects the target magnetic field and generates a detection signal corresponding to the direction of the target magnetic field,
• the magnetic field generator is configured so that a mode of variation of the target magnetic field relative to variations in the position of the rotating body varies nonlinearly relative to the variations in the position of the rotating body,
• the magnetic sensor is configured so that a mode of variation of the detection signal relative to variations in the direction of the target magnetic field varies nonlinearly relative to the variations in the direction of the target magnetic field,
• a target angle that the direction of the target magnetic field forms with respect to a reference direction in the reference plane varies within a first variable range corresponding to a movable range of the position of the rotating body, and
• the detection signal varies within a second variable range corresponding to the first variable range.