Fabrication of a high resolution, low profile credit card reader and card reader for transmission of data by sound

• US 6,579,728 B2
• Filed: 07/12/2001
• Issued: 06/17/2003
• Est. Priority Date: 08/03/1998
• Status: Expired due to Fees

• Current Assignee: Privicom Incorporated
• Original Assignee: Privicom Incorporated
• Inventors: Grant, Alan H., Gambino, Richard J.
• Primary Examiner(s): Niebling, John F.
• Assistant Examiner(s): Roman, Angel
• Application Number:
  US09/902,623
• Publication Number:
  US 20020017568A1
• Time in Patent Office: 705 Days
• Field of Search: 438/3, 438/68, 438/460, 438/462
• US Class Current: 438/3
• CPC Class Codes: G06K 17/0022 arrangements or provisions for transferring data to distant stations, e.g. from a sensing device "transfer between computer elements G06F13/00 "; data-transmission H04L
• CPC Class Codes: G06K 7/084 sensing magnetic material by relative movement detecting flux changes without altering its magnetised state
• CPC Class Codes: G06K 7/087 flux-sensitive, e.g. magnetic, detectors G06K7/10336 takes precedence
• CPC Class Codes: G11B 5/00804 magnetic sheets rotating sheets G11B5/012
• CPC Class Codes: G11B 5/3163 Fabrication methods or processes specially adapted for a particular head structure, e.g. using base layers for electroplating, using functional layers for masking, using energy or particle beams for shaping the structure or modifying the properties of the basic layers
• CPC Class Codes: G11B 5/3903 using magnetic thin film layers or their effects, the films being part of integrated structures
• CPC Class Codes: H10N 50/01 Manufacture or treatment

Abstract

A portable card reader designed to be carried in a wallet or purse has an electromagnetic head that reads information from a magnetic strip of a card or information is read from the card by an array of Hall sensors. In a further embodiment, the card reader uses a magnetic sensor based on magnetoresistive sensing of magnetic transitions of a magnetic stripe, suitable for use with small, portable electronic devices. In each embodiment, the information read from the card may be converted to a sequence of electronic bursts of predetermined frequency, preferably in the audible or ultrasound range. The sound signals are output by a speaker to the microphone of a telephone. The signal is then transmitted over the telephone lines to a remote receiver. The receiver then converts the sound bursts into signal pulses, which can be read using the computer software of a conventional card reader.

Claims

1. A method for fabricating a magnetoresistive sensor from a silicon wafer having a first side and a second side, comprising the steps of:

masking the first side of the silicon wafer with a plurality of substantially parallel strips of masking material spaced from one another;

scribing the second side of the silicon wafer with a first set of substantially parallel scribe lines spaced from one another, said scribed lines being substantially perpendicular to said strips of masking material;

cleaving the wafer along every other scribe line in said first set to produce a plurality of silicon bars with cleaved edges;

coating the silicon bars with permalloy to cover the first side and the cleaved edges;

scribing the coated silicon bars with a second set of substantially parallel scribe lines;

cleaving the bars along said second set of scribe lines to produce a plurality of silicon blocks; and

removing the parallel strips of masking material and cleaving each of said blocks along remaining scribe lines in said first set to produce a plurality of magnetoresistive sensors for use as credit card readers.

2. The method as set forth in claim 1, wherein said plurality of strips of masking material include strips of Kapton tape spaced equidistantly from one another.

3. The method as set forth in claim 2, wherein each strip of Kapton tape is approximately 6 mm wide.

4. The method as set forth in claim 3, wherein a distance from a lateral center of one strip to a lateral center of an adjacent strip is approximately 10 mm.

5. The method as set forth in claim 1, wherein said scribe lines within said first set are spaced approximately 10 mm apart such that each of said plurality of silicon bars is approximately 20 mm in width.

6. The method as set forth in claim 1, wherein the step of coating is performed using ion beam deposition.

7. The method as set forth in claim 1, wherein the step of coating comprises the step of bombarding, at an angle of approximately 45°

, a rough side and the cleaved edges of said silicon bars with a flux of nickel and iron atoms.

8. The method as set forth in claim 1, wherein the step of coating comprises the steps of:

placing the silicon bars on a substrate holder with a polished side facing the substrate holder;

tilting the substrate holder at an angle of approximately 45°

relative to a source of flux;

bombarding the silicon bars with a flux of nickel and iron atoms from the source;

rotating, during the step of bombarding, the substrate holder so that the rough side and the cleaved edges of said silicon bars are coated with permalloy.

9. The method as set forth in claim 1, wherein said scribe lines within said second set are spaced approximately 10 mm apart.

10. The method as set forth in claim 1, wherein the first side is rough and the second side is polished.

11. The method as set forth in claim 10, wherein the silicon wafer has a flat edge and said first set of scribe lines are substantially parallel with said flat edge.

12. The method as set forth in claim 1, further comprising the steps of:

connecting at least one of said magnetoresistive sensors to a circuit having a power supply and a fixed resistor;

scanning a credit card having a magnetic stripe past said at least one sensor;

monitoring, during the step of scanning, a voltage drop across the fixed resistor responsive to magnetic transitions in said magnetic stripe.

13. A method for fabricating a magnetoresistive sensor from a silicon wafer having a rough side and a polished side, comprising the steps of:

masking the rough side of the silicon wafer with parallel strips of tape spaced to be substantially equidistant from one another;

scribing the polished side of the silicon wafer with a first set of substantially parallel scribe lines spaced substantially equidistantly, said first set of parallel scribed lines being substantially perpendicular to said parallel strips of tape;

cleaving the wafer along every other scribe line in said first set to produce a plurality of silicon bars having straight cleaved edges perpendicular to the polished side;

coating the plurality silicon bars with a permalloy to cover the rough side and said cleaved edges;

scribing the coated silicon bars on said rough side with a second set of scribe lines substantially parallel to and spaced substantially equidistantly from edges of adjacent strips of tape;

cleaving the bars along said second set of parallel scribe lines to produce silicon blocks, each block having a strip of tape extending lengthwise substantially down a center of a top surface thereof;

removing the strip of tape from each block and cleaving each of said blocks along remaining scribe lines from said first set to produce a plurality of magnetoresistive sensors for use in scanning a credit card, each sensor having an active region along a respective coated cleaved edge.

14. The method as set forth in claim 13, wherein said plurality of strips of tape include strips of Kapton tape.

15. The method as set forth in claim 14, wherein each strip of Kapton tape is approximately 6 mm wide.

16. The method as set forth in claim 15, wherein a distance from a lateral center of one strip to a lateral center of an adjacent strip is approximately 10 mm.

17. The method as set forth in claim 13, wherein said scribe lines within said first set are spaced approximately 10 mm apart such that each of said plurality of silicon bars is approximately 20 mm in width.

18. The method as set forth in claim 13, wherein the step of coating is performed using ion beam deposition.

19. The method as set forth in claim 18, wherein the wafer is approximately 1 mm thick and said active region is approximately 6 mm long, 1 mm high and 100 nm in thickness.

20. The method as set forth in claim 13, wherein the step of coating comprises the step of bombarding, at an angle of approximately 45°

, the rough side and the cleaved edges of said silicon bars with a flux of nickel and iron atoms.

21. The method as set forth in claim 13, wherein the step of coating comprises the steps of:

placing the silicon bars on a substrate holder with the polished side facing the substrate holder;

tilting the substrate holder at an angle of approximately 45°

relative to a source of flux;

bombarding the silicon bars with a flux of nickel and iron atoms from the source;

rotating, during the step of bombarding, the substrate holder so that the rough side and the cleaved edges of said silicon bars are coated with permalloy.

22. The method as set forth in claim 13, wherein said scribe lines within said second set are spaced approximately 10 mm apart.

23. The method as set forth in claim 13, further comprising the steps of:

connecting at least one of said magnetoresistive sensors to a circuit having a power supply and a fixed resistor;

scanning a credit card having a magnetic stripe past said at least one sensor;

monitoring, during the step of scanning, a voltage drop across the fixed resistor responsive to magnetic transitions in said magnetic stripe.

24. The method as set forth in claim 13, wherein the silicon wafer has a flat edge and said first set of scribe lines are substantially parallel with said flat edge.

25. A method for fabricating a credit card reader from a silicon wafer having a rough side, a polished side and a flat edge, comprising the steps of:

masking the rough side of the silicon wafer with parallel strips of tape spaced to be substantially equidistant from one another;

scribing the polished side of the silicon wafer with a first set of substantially parallel scribe lines spaced substantially equidistantly, said first set of parallel scribed lines being substantially parallel with said flat edge and substantially perpendicular to said parallel strips of tape;

cleaving the wafer along every other scribe line in said first set to produce a plurality of silicon bars having straight cleaved edges perpendicular to the polished side;

coating the plurality silicon bars with a permalloy using ion beam deposition to cover the rough side and said cleaved edges;

scribing the coated silicon bars on said rough side with a second set of scribe lines substantially parallel to and spaced substantially equidistantly from edges of adjacent strips of tape;

cleaving the bars along said second set of parallel scribe lines to produce a plurality of silicon blocks, each block having a strip of tape extending lengthwise substantially down a center of a top surface thereof;

removing the strip of tape from each block and cleaving each of said blocks along remaining scribe lines from said first set to produce a plurality of magnetoresistive sensors, each sensor having an active region along a respective coated cleaved edge; and

connecting at least one of said magnetoresistive sensors to a circuit having a power supply and a fixed resistor.

26. The method as set forth in claim 25, wherein each strip of tape is approximately 6 mm wide.

27. The method as set forth in claim 26, wherein a distance from a lateral center of one strip to a lateral center of an adjacent strip is approximately 10 mm.

28. The method as set forth in claim 25, wherein said scribe lines within said first set are spaced approximately 10 mm apart such that each of said plurality of silicon bars is approximately 20 mm in width.

29. The method as set forth in claim 25, wherein the step of coating comprises the step of bombarding, at an angle of approximately 45°

, the rough side and the cleaved edges of said silicon bars with a flux of nickel and iron atoms.

30. The method as set forth in claim 25, wherein the step of coating comprises the steps of:

placing the silicon bars on a substrate holder with the polished side facing the substrate holder;

tilting the substrate holder at an angle of approximately 45°

relative to a source of flux;

bombarding the silicon bars with a flux of nickel and iron atoms from the source;

rotating, during the step of bombarding, the substrate holder so that the rough side and the cleaved edges of said silicon bars are coated with permalloy.

31. The method as set forth in claim 25, wherein said scribe lines within said second set are spaced approximately 10 mm apart.

32. The method as set forth in claim 25, further comprising the steps of:

scanning a credit card having a magnetic stripe past said at least one sensor;

monitoring, during the step of scanning, a voltage drop across the fixed resistor responsive to magnetic transitions in said magnetic stripe.

33. The method as set forth in claim 25, wherein said plurality of strips of tape include strips of Kapton tape.

34. The method as set forth in claim 25, wherein the wafer is approximately 1 mm thick and said active region is approximately 6 mm long, 1 mm high and 100 nm in thickness.