Bar code, as well as process and apparatus for reading the same

• US 5,430,278 A
• Filed: 11/16/1992
• Issued: 07/04/1995
• Est. Priority Date: 09/23/1989
• Status: Expired due to Fees

• Current Assignee: Prof. Dr. Gunther Krieg
• Original Assignee: Gunther Krieg
• Inventors: Hanke, Andreas, Baldas, Otmar, Krieg, Gunther
• Primary Examiner(s): PITTS, HAROLD I
• Application Number:
  US07/977,254
• Time in Patent Office: 960 Days
• Field of Search: 235/449, 235/493
• US Class Current: 235/449
• CPC Class Codes: G06K 19/06187 with magnetically detectable marking
• CPC Class Codes: G06K 7/087 flux-sensitive, e.g. magnetic, detectors G06K7/10336 takes precedence

Abstract

A process in which by a bar code formed by bars are gaps located between them with different electromagnetic characteristics, an electromagnetic alternating field is produced and a measuring field variable by the bar code is detected. At lease one sensor is provided with a sensor core, an exciting coil subject to high frequency located thereon and in each case at least one sensor coil closely adjacent to the exciting coil. The bar code is formed by electrically conductive material bars placed on a carrier with gaps.

Claims

1. Process for reading a bar code including diamagnetic or paramagnetic bars and gaps therebetween, said diamagnetic or paramagnetic bars having different electrical conductivities, the process comprising the steps of:

bringing the bar code under a combined generating and reading head,

generating an electromagnetic A.C. field by the bar code, said electromagnetic A.C. field generating a rotational field in the electrically, conducting bars of the bar code, and

detecting at the same time the generated rotational field as a measuring field altered by the bar code, thereby enabling the bar code to be read by said combined generating and reading head,

whereby said bar code having different electrical conductivities is brought under said combined generating and reading head and said electromagnetic A.C. field is generated by the bar code and generates said rotational field in the electrically conducting bars of the bar code and the generated rotational field is simultaneously detected as the measuring field altered by the bar code so as to enable the bar code to be read by said combined generating and reading head.

2. Process according to claim 1, further comprising the step of compensating the measuring field to zero at a position remote from the bar code.

3. Process according to claim 2, further comprising the step of detecting a reference field not influenceable by the bar code, and adjusting a measuring field to zero.

4. Process according to claim 2, wherein the measuring field is purely electronically compensated to zero.

5. Process according to one of claims 1 or 2, wherein several juxtaposed exciting fields are produced through the bar code in a fixed spacing and at right angles to an extension of individual bars of the bar code, and wherein measuring signals are taken.

6. Process according to claim 4, wherein exciting fields are produced and the measuring signals tapped.

7. Apparatus for reading a bar code including diamagnetic or paramagnetic bars and gaps, with the diamagnetic or paramagnetic bars having different electrical conductivities, the apparatus comprising:

at least one combined sensor means including a sensor core,

an exciting coil exposed to high frequency located on said sensor core, and

at least one sensor coil disposed closely adjacent to the exciting coil on the same sensor core,

whereby said high frequency voltage is applied to said exciting coil to produce a magnetic alternating field to induce a voltage in the one sensor coil being disposed closely adjacent to the exciting coil on the sensor core.

8. Apparatus according to claim 7, wherein the at least one sensor coil is provided on the sensor core, and wherein said at least one sensor coil includes a measuring and a reference coil.

9. Apparatus according to one of claims 7 or 8, wherein the sensor core is H-shaped, and the exciting coil is disposed on a web of the H-shaped core, and the at least one sensor coil is disposed on the legs of the H-shaped core.

10. Apparatus according to claim 9, wherein the sensor core tapers in an A-shaped manner at least to one end of adjacent legs of the H-shaped core, and wherein a gap is provided between portions of the legs of the sensor core.

11. Apparatus according to claim 10, wherein the sensor core tapers from the web in a direction of free ends of the legs.

12. Apparatus according to claim 10, wherein an end face formed by adjacent legs of the sensor core forms a circle provided with a slot.

13. Apparatus according to one of claims 7 or 8, wherein the sensor core is E-shaped, and wherein windings of the sensor coils are placed on legs of the E-shaped sensor core.

14. Apparatus according to one of claims 7 or 8, wherein the sensor is constructed symmetrically with an exciting rod, and wherein measuring cylinders surround the ends of the exciting rod.

15. Apparatus according to claim 8, wherein the coil are bonded to the sensor core.

16. Apparatus according to claim 8, wherein a parallel connection of capacitors is provided to the coils.

17. Apparatus according to one of claims 7 or 8, wherein means are provided for enabling a zero adjustment of a measuring voltage.

18. Apparatus according to claim 8, wherein the reference and measuring coils are oppositely connected in series.

19. Apparatus according to one of claims 7 or 8, further comprising series-connected phase shifters and differential amplifiers.

20. Apparatus according to one of claims 7 or 8, further comprising a peak value detection device with a series connected flip-flop.

21. Bar code, comprising a carrier, a plurality of bars disposed on said carrier and being respectively separated by a gap, said bars being formed of electrically conductive material, wherein the electrically conductive material of the respective bars are different from each other, and wherein the gaps are optionally filled with another material, whereby said bars of said bar code receive a high frequency voltage and said high frequency voltage is modified by said electrically conductive material.

22. Bar code according to claim 21, wherein each of the bars are covered by a top coating.

23. Bar code according to one of claims 21 or 22, wherein the bars are made from one of a paramagnetic and diamagnetic material.

24. Bar code according to one of claims 21 or 22, wherein the bars are made from a ferromagnetic material.

25. Bar code according to claim 22, wherein at least one of the carrier and the coating is made from dielectric material.

26. Bar code according to claim 22, wherein at least one of the carrier and the coating is made from a ferromagnetic material.

27. Bar code according to claim 22, wherein at least one of the carrier and the coating is made from paramagnetic or diamagnetic material.