Pancake annunciator

In combination with a medical device encapsulated within a casing and implantable in the body of a patient, an annunciator comprising:

• a magnetically permeable stationary ring member fixed to the casing including an integral radially inwardly projecting peripheral flange having first and second opposed sides;
• a first electrically conductive coil mounted on the peripheral flange adjacent the first side;
• a second electrically conductive coil mounted on the peripheral flange adjacent the second side;
• an oscillating member encompassed by the stationary ring member including a planar magnet member having first and second opposed surfaces of opposite polarity and first and second planar pole pieces mounted to the first and second surfaces, respectively, in a sandwich-like construction, the oscillating member having a longitudinal axis and being movable along the axis between a first extreme position whereat the first pole piece is proximate the peripheral flange and a second extreme position whereat the second pole piece is proximate the peripheral flange;
• and
• axially compliant spider means extending between the oscillating member at the longitudinal axis and the ring member for biasing the oscillating member toward a neutral position intermediate the first and second extreme positions;
• whereby cyclic energization of the first and second electrically conductive coils with an electrical current generates a cyclically alternating magnetic field which interacts with the magnetic field of the oscillating member to cause the oscillating member to oscillate between the first and second extreme positions.

An activity sensor for a medical device encapsulated within a casing and implantable in the body of a patient comprising:

• a magnetically permeable stationary ring member including an integral inwardly projecting peripheral flange having first and second opposed sides;
• a first electrically conductive coil mounted on the peripheral flange adjacent the first side;
• a second electrically conductive coil mounted on the peripheral flange adjacent the second side;
• an oscillating member encompassed by the stationary ring member including a planar magnet member having first and second opposed surfaces of opposite polarity and first and second planar pole pieces mounted to the first and second surfaces, respectively, in a sandwich-like construction, the oscillating member having a longitudinal axis and being movable along the axis between a first extreme position whereat the first pole piece is proximate the peripheral flange and a second extreme position whereat the second pole piece is proximate the peripheral flange;
• whereby relative motion between the oscillating member and the conductive coils imparted by movement of the casing causes interaction of the coil with the magnetic field of the oscillating member to produce a voltage and a resulting current through the coil which is proportional to velocity, thereby detecting activity on the part of the patient.

An annunciator for a medical device encapsulated within a casing and implantable in the body of a patient comprising:

• a magnetically permeable stationary ring member including an integral inwardly projecting peripheral flange having first and second opposed sides;
• a first electrically conductive coil mounted on the peripheral flange adjacent the first side;
• a second electrically conductive coil mounted on the peripheral flange adjacent the second side;
• a free floating oscillating member encompassed by the stationary ring member including a planar magnet member having first and second opposed surfaces of opposite polarity and first and second planar pole pieces mounted to the first and second surfaces, respectively, in a sandwich-like construction, the oscillating member having a longitudinal axis and being movable along the axis between a first extreme position whereat the first pole piece is proximate the peripheral flange and a second extreme position whereat the second pole piece is proximate the peripheral flange;
• whereby cyclic energization of the first and second electrically conductive coils with an electrical current generates a cyclically alternating magnetic field which interacts with the magnetic field of the oscillating member to cause the oscillating member to oscillate between the first and second extreme positions.

In combination with a medical device encapsulated within a casing and implantable in the body of a patient, an annunciator comprising:

• a magnetically permeable stationary ring member fixed to the casing including an integral radially inwardly projecting peripheral flange having first and second opposed sides;
• a first electrically conductive coil mounted on the peripheral flange adjacent the first side;
• a second electrically conductive coil mounted on the peripheral flange adjacent the second side;
• a free floating oscillating member encompassed by the stationary ring member including a planar magnet member having first and second opposed surfaces of opposite polarity and first and second planar pole pieces mounted to the first and second surfaces, respectively, in a sandwich-like construction, the oscillating member having a longitudinal axis and being movable along the axis between a first extreme position whereat the first pole piece is proximate the peripheral flange and a second extreme position whereat the second pole piece is proximate the peripheral flange;
• whereby cyclic energization of the first and second electrically conductive coils with an electrical current generates a cyclically alternating magnetic field which interacts with the magnetic field of the oscillating member to cause the oscillating member to oscillate between the first and second extreme positions.