Apparatus for detecting metal parts which are movable relative to a metal sensitive sensor arrangement

• US 5,187,723 A
• Filed: 05/31/1991
• Issued: 02/16/1993
• Est. Priority Date: 06/01/1990
• Status: Expired due to Fees

• Current Assignee: Harro Mueller-Stuercken
• Original Assignee: Harro Mueller-Stuercken
• Inventors: Mueller-Stuercken, Harro
• Primary Examiner(s): Heyman, John S.
• Application Number:
  US07/707,887
• Time in Patent Office: 627 Days
• Field of Search: 377/6, 377/9, 377/33, 340/674, 340/944, 331/65, 324/232, 324/243, 324/236, 324/325, 324/326, 324/327, 324/225
• US Class Current: 377/6
• CPC Class Codes: G01V 3/101 by measuring the impedance of the search coil; by measuring features of a resonant circuit comprising the search coil measuring impedance or characteristics derived therefrom G01R27/00, e.g. quality factor G01R27/26
• CPC Class Codes: H03K 17/9502 Measures for increasing reliability

Abstract

An apparatus for the detecting of metal parts (12) which move relative to a metal sensitive sensor arrangement has at least two part sensors which transmit an electrical pulse to an electronic evaluation circuit for a particular approach by a metal part (12). Several part sensors are connected spatially in series with one another so that a specific metal part (12) causes the part sensors to respond in sequence. The electronic evaluation circuit (13) then transmits a signal when and only when it detects the pulse sequence which arises through sequential response of the part sensors.

Claims

1. An apparatus for detecting and counting metal objects which comprises

a sensor, comprising a plurality of

sub-sensors, each connected to sense the motion of a metal object in proximity thereto, said sub-sensors being disposed so that the metal object to be detected passes said sub-sensors seriatim;

an electronic sensing circuit, comprising

a plurality of pulse generators, one for each sub-sensor, each said generator coupled to one said sub-sensors to generate a pulse in response to a metal object passing near said sub-sensor, each said generator containing

an oscillator coupled to said sub-sensor, connected to change frequency in response to a metal object passing near said sub-sensor;

a logic circuit, comprising

an exclusive OR-gate, having a plurality of inputs and an output, each of said inputs being coupled to one of said pulse generators; and

a counter, coupled to the output of said exclusive OR-gate, which transmits a detection signal after counting a predetermined number of pulses.

2. An apparatus for detecting and counting metal objects which comprises,

a sensor, comprising a plurality of

sub-sensors, each sub-sensor comprising a flat, ring-like coil winding having an axis perpendicular to the plane of said coil winding and an opening in the center of said coil winding, said sub-sensors connected to respond to the motion of a metal object through said opening, and said sub-sensors being disposed substantially coaxially;

and

a plurality of short circuit rings, composed of electrically conductive material, one said short circuit ring disposed between each adjacent pair of ring like coil windings and substantially coaxial therewith; and

an electronic sensing circuit coupled to said sub-sensors, said sensing circuit connected to transmit an output signal when, and only when, said sub-sensors respond in a predetermined sequence.

3. An apparatus for detecting and counting metal objects which comprises,

a sensor, comprising a plurality of

sub-sensors, each sub-sensor comprising a flat, ring-like coil winding having an axis perpendicular to the plane of said coil winding and an opening in the center of said coil winding, said sub-sensors connected to respond to the motion of a metal object through said opening, and said sub-sensors being disposed substantially coaxially;

an electronic sensing circuit, coupled to said sub-sensors, said sensing circuit connected to transmit an output signal when, and only when, all of the sub-sensors respond seriatim; and

direction sensing means to selectively respond to one or more predetermined sequences of sub-sensor responses.

4. An apparatus for detecting and counting metal objects which comprises,

a sensor, comprising a plurality of

sub-sensors, each adapted to respond to the motion of a metal object in proximity thereto;

an electronic sensing circuit, comprising

a plurality of pulse generators, one for each sub-sensor, connected to produce a pulse when said sub-sensor responds to the motion of said metal object; and

a logic circuit, comprising

an exclusive OR-gate, having a plurality of inputs and an output, with each of said inputs coupled to one of said pulse generators; and

a counter, having a data input, coupled to the output of said exclusive OR-gate, and a reset input, said counter connected to transmit a detect signal after counting a predetermined number of pulses;

a further OR-gate, having a plurality of inputs, each input coupled to a different generator, and an output

a delay stage, having an input coupled to said further OR-gate and an output;

an inverting stage, having an input coupled to the output of said first generator and an output; and

a third OR-gate, having a first input coupled to the output of said inverting stage, a second input coupled to the output of said delay stage, and an output coupled to the reset input of said counter.

5. An apparatus for detecting and counting metal objects which comprises,

a sensor, comprising a plurality of

sub-sensors, each connected to respond to the motion of a metal object in proximity thereto;

a plurality of pulse generators, coupled to said sub-sensors and connected to generate a pulse when said sub-sensors detects the motion of a metal object; and

a logic circuit, comprising

an exclusive OR-gate, having a plurality of inputs and an output, with each of said inputs coupled to one of said pulse generators;

an AND-gate, having a first input, a second input, and an output, said first input being coupled to the output of said exclusive OR-gate;

a reversing stage, having an input coupled to the output of said AND-gate and an output; and

a flip flop, having an input coupled to the output of said reversing stage and having an output coupled to the said second input of said AND-gate.