Displacement sensor

• US 4,805,633 A
• Filed: 12/31/1987
• Issued: 02/21/1989
• Est. Priority Date: 01/26/1987
• Status: Expired due to Fees

• Current Assignee: TDK Corporation
• Original Assignee: TDK Corporation
• Inventors: Takahashi, Minoru, Kotani, Tsutomu
• Primary Examiner(s): CHAMBERS, A MICHAEL
• Application Number:
  US07/140,043
• Time in Patent Office: 418 Days
• Field of Search: 324/247, 128/715, 128/773, 128/687, 381/67, 381/177
• US Class Current: 600/528
• CPC Class Codes: A61B 2562/0204 Acoustic sensors
• CPC Class Codes: A61B 5/11 Measuring movement of the entire body or parts thereof, e.g. head or hand tremor, mobility of a limb for measuring pulse A61B5/02 ;A61B5/1038 takes precedence; motion detection to correct for motion artifacts in physiological signals A61B5/721
• CPC Class Codes: A61B 7/04 Electric stethoscopes microphones, acoustic transducers therefor H04R
• CPC Class Codes: G01D 5/2033 controlling the saturation of a magnetic circuit by means of a movable element, e.g. a magnet

Abstract

A displacement sensor or an electrocardiogram attaches a permanent magnet chip directly on a living body, and movement or vibration of the living body is sensed by measuring flux by said magnet. The displacement sensor has a magnet assembly having an adhesive film mounting a permanent magnet at the center of the film supported on a bottom ring which has a plurality of upright walls with jaws, for detachably engaging the magnet assembly with a sensor body. The sensor body has saturable inductors which are placed in flux by said magnet and are coupled with a process circuit having an astable multivibrator with a collector load by said saturable inductors and a low-pass filter connected to the output of the multivibrator. The magnet assembly is first adhered on a living body, then, the sensor body is engaged with the same by engaging said jaws with a ring on the sensor body, then, the process circuit provides an output signal reflecting the movement of a living body.

Claims

1. A displacement sensor comprising;

a sensor body having a substrate (16), a plurality of saturable inductors connected alternately in series mounted on one surface of said substrate radially with a predetermined angular period, each of said saturable inductors having a saturable magnetic core and a coil wound on the core, a process circuit (15) for processing output of said saturable inductors mounted on the other surface of said substrate, a lead wire coupled with said process circuit for supplying power to said process circuit and obtaining output of the process circuit, a shield case (31) surrounding said process circuit, and a housing (32) for securing above members having a ring (32a) on external wall of the housing, and

a magnet assembly having a bottom ring (38a) with a plurality of upright wall chips (41) positioned perpendicularly at periphery of said bottom ring, a film (39) having a permanent magnet at center of said film attached to said bottom ring, each of said wall chips having a jaw at the extreme end so that said jaw engages detachably with said ring (32a) of the housing (32), and a plurality of bars (43) fixed to said bottom ring (38) so that it touches with said sensor body when it is engaged with the magnet assembly, and said magnet is positioned close to said saturable inductors.

2. A displacement sensor according to claim 1, wherein said film is transparent.

3. A displacement sensor according to claim 1, wherein said film is adhesive, and is adhered on a body which is subject to sense.

4. A displacement sensor according to claim 1, wherein more than four wall chips are provided.

5. A displacement sensor according to claim 1, wherein said saturable magnetic core is made of amorphous material.

6. A displacement sensor according to claim 1, wherein said process circuit has an astable multivibrator with a collector load by said saturable inductors, and a low-pass filter coupled with output of said multivibrator to obtain displacement output signal according to position of said magnet.