Sensor for measuring the magnetically responsive characteristics of tokens

• US 5,119,916 A
• Filed: 03/27/1990
• Issued: 06/09/1992
• Est. Priority Date: 03/27/1990
• Status: Expired due to Fees

• Current Assignee: Duncan Parking Technologies, Inc. (Navient Corp.)
• Original Assignee: Duncan Industries Parking Control Corporation
• Inventors: Carmen, Ralph H., Van Horn, John W.
• Primary Examiner(s): Bartuska, F. J.
• Application Number:
  US07/499,719
• Time in Patent Office: 805 Days
• Field of Search: 194/317, 194/318, 194/319, 194/320, 194/210, 235/450, 453/3, 453/4
• US Class Current: 194/210
• CPC Class Codes: G07D 5/02 Testing the dimensions, e.g. thickness, diameter; Testing the deformation
• CPC Class Codes: G07D 5/08 Testing the magnetic or electric properties

Abstract

An improved magnetic field sensor for detecting tokens is disclosed which has one Hall effect sensor located between a magnet and an inclined token track base and another Hall effect sensor located between another magnet and the inclined token track base. The Hall effect sensors are placed at distances above the inclined token track base which optimize their accuracy in detecting tokens which have two concentric regions with different magnet characteristics.

Claims

1. A magnetic field sensor assembly for producing an electric signal indicative of the magnetic characteristic of a token rolling along a track, the magnetic field sensor assembly comprising:

A. first means for producing a magnetic field;

B. first magnetic field sensing means for producing a first electric signal influenced by the magnetic field at said first magnetic field sensing means, said first electric signal changing in response to changes in the magnetic field at said first magnetic field sensing means, said first means held in position in said assembly a first predetermined distance from said first magnetic field sensing means, said assembly adapted to be positioned adjacent said track, whereby said first magnetic field sensing means can be spaced a second predetermined distance from said track and between said first means and said track;

C. an outer shell within which are mounted said magnetic field producing means and said magnetic field sensing means; and

,

D. a plurality of ribs integral to said outer shell, each of said ribs having a projecting portion which separates said magnetic field producing means and said magnetic field sensing means, said projecting portions thereby defining said first predetermined distance, said first predetermined distance being chosen so as to help keep tokens for being captured by the magnetic field and held against said magnetic field sensing means while maintaining the sensitivity of said sensing means.

2. The magnetic field sensor assembly of claim 1, further comprising:

A. second means for producing a magnetic field;

B. second magnetic field sensing means for producing a second electric signal influenced by the magnetic field at said second magnetic field sensing means, said second electric signal changing in response to changes in the magnetic field at said second magnetic field sensing means, said second means held in position in said assembly a third predetermined distance from said second magnetic field sensing means, said second magnetic field sensing means held in position in said assembly a fourth predetermined distance in a first predetermined direction from said first magnetic field sensing means, said assembly adapted to be positioned adjacent said track, whereby said second magnetic field sensing means can be spaced a fifth predetermined distance from said track and between said second means and said track.

3. The magnetic field sensor assembly of claim 2, wherein said second means is held in position in said assembly substantially said fourth predetermined distance in substantially said first predetermined direction from said first means.

4. The magnetic field sensor assembly of claim 2, wherein said third predetermined distance is substantially equal to said first predetermined distance.

5. The magnetic field sensor assembly of claim 2, wherein said fifth predetermined distance is substantially equal to said second predetermined

6. The magnetic field sensor assembly of claim 2, wherein:

A. said second means is held in position in said assembly substantially said fourth predetermined distance in substantially said first predetermined direction from said first means;

B. said third predetermined distance is substantially equal to said first predetermined distance; and

C. said fifth predetermined distance is substantially equal to said second predetermined distance.

7. The magnetic field sensor assembly of claims 2, 3, 4, 5, or 6, wherein:

A. said first means comprises a permanent magnet;

B. said second means comprises a permanent magnet;

C. said first magnetic field sensing means comprises a Hall-effect detector; and

D. said second magnetic field sensing means comprises a Hall-effect detector.

8. The magnetic field sensor assembly of claim 7, further comprising analog signaling means for producing an analog signal indicative of said first electric signal and of said second electric signal.

9. The magnetic field sensor assembly of claim 8, further comprising programmable microprocessor means for receiving said analog signal and for asserting a reset signal, and wherein said analog signaling means further comprises first latch means for asserting said analog signal, said first latch means clearing said analog signal in response to the assertion of said reset signal.

10. The magnetic field sensor assembly of claim 7, further comprising digital signaling means for producing a digital signal indicative of said first electric signal and of said second electric signal.

11. The magnetic field sensor assembly of claim 10, further comprising programmable microprocessor means for receiving said digital signal and for asserting a reset signal, and wherein said digital signaling means further comprises second latch means for asserting said digital signal, said second latch means clearing said digital signal in response to the assertion of said reset signal.

12. The magnetic field sensor assembly of claim 11, wherein said second latch means is connected between a source of higher potential and a source of lower potential, said second latch means clearing if said source of higher potential is pulsed low and then returned high, and further comprising means, responsive to said reset signal, for pulsing said source of higher potential low and then returning said source of higher potential high.

13. The magnetic field sensor assembly of claim 8, wherein:

A. said analog signaling means produces a first analog signal if said first electric signal and said second electric signal both change by more than a predetermined amount in response to the passage of a token;

B. said analog signaling means produces a second analog signal if said first electric signal changes by more than said predetermined amount in response to the passage of a token and said second electric signal changes by less than said predetermined amount in response to the passage of a token; and

C. said analog signaling means produces a third analog signal if said first electric signal does not change by more than said predetermined amount in response to the passage of a token and said second electric signal does not change by more than said predetermined amount in response to the passage of a token.

14. The magnetic field sensor of claim 10,

A. said digital signaling means produces a first digital signal if said first electric signal and said second electric signal both change by more than a predetermined amount in response to the passage of a token;

B. said digital signaling means produces a second digital signal if said first electric signal changes by more than said predetermined amount in response to the passage of a token and said second electric signal does not change by more than a predetermined amount in response to the passage of a token; and

C. said digital signaling means produces a third digital signal if said first electric signal does not change by more than said predetermined amount in response to the passage of a token and said second electric signal does not change by more than said predetermined amount in response to the passage of a token.