EP1177548A1

EP1177548A1 - Magnetic read head having decode circuitry

Info

Publication number: EP1177548A1
Application number: EP00914809A
Authority: EP
Inventors: Stephen R. Wood
Original assignee: Axiohm Transaction Solutions Inc
Current assignee: Axiohm Transaction Solutions Inc
Priority date: 2000-03-02
Filing date: 2000-03-02
Publication date: 2002-02-06
Also published as: AU2000236150A1; WO2001065546A1

Abstract

The present invention features a magnetic read head (10') having electronic decode circuitry (44') provided within or adjacent to the head case. No low-level, analog signals, which are generally highly susceptible to electrical noise, leave the head structure. Power and ground signals are provided to the hybrid head (50). Digitized data corresponding to encoded information upon the magnetic stripe (32) on a credit card, ID badge, or similar article is provided at output terminals. Decoding is performed by an ASIC or similar device located at the read head. A data strobe signal and/or a magnetic medium (28) detected signal may also be provided by the read head.

Description

MAGNETIC READ HEAD HAVING DECODE CIRCUITRY

Field of the Invention:

This invention pertains to magnetic read heads and, more particularly, to magnetic read heads adapted to read information from a magnetic stripe and, using decoding circuitry at the head structure, adapted to output digitized information corresponding to the information encoded on the magnetic stripe.

BACKGROUND OF THE INVENTION

Magnetic read heads have been used for many years for such diverse applications as playing back music and/or video signals from a magnetic medium, such as a tape or stripe, reading magnetic characters on the bottom of checks, and reading magnetically encoded information from magnetic stripes on credit cards, telephone calling cards, access badges, tickets, and the like. Generally, the heads of the prior art feature a magnetic pole piece having a precision gap at or near the point of contact with the media to be read. One or more coils of wire wound around the magnetic pole piece generate a voltage in response to a change in a magnetic field near the head gap. The electrical signal induced in the head is then amplified, filtered and eventually decoded to retrieve the information from the magnetic medium. Heretofore, magnetic read heads have generally been stand-alone structures. Only the pole piece, housing and winding have been packaged as a single device .

United States Patent No. 3,612,835 for COMBINED OPTICAL AND MAGNETIC TRANSDUCER; issued October 12, 1971 to Boley A. Andrews, et al . , teaches a magnetic read head with an optical transducer installed within the head assembly. ANDREWS, however, teaches no electronic circuitry. Both the magnetic and the optical transducers generate small- amplitude analog signals which are unmodified within the head structure. In contradistinction, the magnetic head of the present invention includes decode electronics so that no analog, small -amplitude signals leave the head assembly. Rather a decoded, digital signal is presented at the output terminals of the read assembly, or an attached cable assembly.

United States Patent No. 5,117,097 for KEY SYSTEM FOR A VEHICLE; issued May 26, 1992 to Takashi Kimura, et al . , teaches a tuned resonant circuit packaged within a key structure. While not a magnetic read head, the KIMURA structure does include a pole piece (i.e., the protruding extension of the key structure) having a winding thereupon. Discreet inductive and capacitive elements are connected to the winding to form a resonant circuit. The inventive read head, on the other hand, encompasses a structure to read information from a magnetic stripe or the like and, using self-contained circuitry, to provide a digital output signal corresponding to the information on the magnetic stripe. The inventive head does not rely on a resonant circuit comprising inductive and/or capacitive elements connect to the read head winding.

United States Patent No. 5,212,602 for MAGNETIC HEAD HAVING A FUSE WITHIN HEAD CASE; issued May 18, 1998 to Hidefumi Suzuki teaches a magnetic head with a fuse physically within the head structure. The fuse is connected m series with the read head and is used to permanently disable the read head at end-of-life to prevent fraudulent use of the head (e.g., forging credit cards). The inventive read head, however, contains no fuse or similar structure designed to disable the head. Rather, the inventive head features an on-board decode electronics package designed to convert low-level, analog signals read from a magnetic stripe into a digital output signal. Finally, United States Patent No. 5,450,263 for THIN FILM INDUCTORS, INDUCTOR NETWORK AND INTEGRATION WITH OTHER PASSIVE AND ACTIVE DEVICES; issued September 12, 1995 to Chan M. Desaigoudar, et al . teaches a fabrication technique for forming thin- film inductors, capacitors, resistors and semiconductors on a thin substrate. These components, used m combination, are capable of constructing a multichannel, magneto-resistive or similar type read head. The magnetic read head of the instant invention, however, is totally different. A physical coil of wire wound upon a pole piece, not a thm-film inductor, is used as a traditional inductive pickup. Additional circuitry within or near the head casing is used not as a part of the pickup portion of the head, but rather as decode electronics to convert a low-level, analog signal induced m the read head winding into a digital output signal .

It is therefore an object of the invention to provide a read head for reading encoded information from a magnetic stripe or similar magnetic medium.

It is a further object of the invention to provide a read head having decode electronics packaged within the head casing or packaged as a monolithic part of the head, forming a unitary structure.

It is an additional object of the invention to provide a read head adapted to receive power, ground and control signals and to provide a digital output signal at a standard, predetermined signal level.

It is a still further object of the invention to provide a read head which provides a magnetic media detected signal.

It is yet another object of the invention to provide a read head with a low susceptibility to external electrical noise . It is another object of the invention to provide a read head with a case and flex circuitry or other such interconnection means, to supply power to the head, receive decoded signals from the head, or transmit digital signals to the head.

It is a still further object of the invention to provide a hybrid read head with decode electronics which has a higher reliability and lower cost than do magnetic read heads with external decode electronics.

SUMMARY OF THE INVENTION

The present invention features a magnetic read head having built-in electronic decode circuitry. No low-level, analog signals, which are generally highly susceptible to electrical noise, leave the head structure. Power and ground are provided to the hybrid head. Digitized data corresponding to encoded information upon a magnetic stripe on a credit card, I.D. badge, or similar article is provided at output terminals, attached cables, or other interconnections. In addition, a data strobe signal is provided by the head. An optional magnetic media detected signal may also be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

A complete understanding of the present invention may be obtained by reference to the accompanying drawings, when taken in conjunction with the detailed description thereof and in which:

FIGURE 1 is a cross-sectional, schematic drawing of a typical magnetic read head of the prior art;

FIGURE 2 is a schematic block diagram of a typical magnetic stripe reading system of the prior art;

FIGURE 3 is a schematic block diagram of the read head with decode electronics of the invention;

FIGURE 4a is a schematic top view of an alternate embodiment of the read head with decode electronics wherein the decode electronics are mounted on a substrate attached to the back of a read head;

FIGURE 4b is a schematic rear view the embodiment of the read head shown in FIGURE 4a;

FIGURE 5 is a schematic view of the read head and decode electronics shown in FIGURE 4 and also showing an attached cable and connector; and

FIGURE 6 is a schematic view of a third embodiment of the read head with decode electronics wherein the decode electronics are mounted on a substrate integrally attached to a flexible circuit assembly.

The same or similar reference numerals are used throughout the drawings to depict like components.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Generally speaking, this invention relates to a magnetic read head for use in recovering encoded information from the magnetic stripe on a credit card or similar article. More specifically, there is disclosed a magnetic read head having decode electronics which provide a digital signal output.

Referring first to FIGURE 1, there is shown generally at reference number 10, a cross-sectional view of a typical magnetic read head. A core 12 is constructed from a high- permeability material such as mumetal or ferrite. Ferrite cores 12 are generally solid pieces of material while those constructed from steel or mumetal are often laminated to reduce eddy currents in the core 12 structure. Core 12 is discontinuous at an apex region 16. A winding coil 14 is wrapped around core 12 such that magnetic flux (not shown) m core 12 induces a voltage m the winding 14 which terminates at external connectors 24. An optional shim 18 may be placed m the gap m core 12 at apex region 16. Core 12, winding 14 and optional shim 18 are all enclosed m a common housing 20. A potting material 22 may be used to fill the space m housing 20 not occupied by the head components, thereby securing the components. Housing 20 is generally constructed from a high permeability material which provides magnetic shielding to the coil 14 of head assembly 10.

Referring now to FIGURE 2, there is shown a simplified, schematic block diagram of a typical magnetic read head 10 of the prior art shown "reading" information from a magnetically-encoded article 28. The article 28 comprises a plastic substrate 30 with a magnetic stripe 32 disposed thereupon. This is a construction typically used for credit cards, ID badges, hotel keys, and many other applications and structures well known to those skilled m the art .

When article 28 is moved past read head 10 as shown by arrow 34, magnetic information (not shown) previously encoded onto magnetic stripe 32 induces a small voltage into winding 14 of head 10. This voltage is coupled to an amplifier 36 along a wire or cable 38. Cable 38 generally has a shield 40 connected to ground 42. Shield 40 is designed to protect the small voltage generated by head 10 from interference by electromagnetic fields (not shown) m the region of cable 38. Amplifier 36 is generally provided with a differential input to help minimize common-mode interference. Other strategies and/or amplifier configurations are well known to those skilled m the circuit design art. An output signal from amplifier 36 is provided to a decode circuit 44 where the amplified, analog signal from head 10 is converted to a digital signal at a standard voltage. Decode circuitry suitable for use m the application of magnetic stripe reading is well known m the art, as is exemplified, for example, m United States Patent No. 5,240,523 for DECODING FOR MAGNETIC STRIPE RECORDING; issued to George R. Steele.

Referring now to FIGURE 3, there is shown a simplified schematic block diagram of the magnetic read head 50 of the present invention shown "reading" information from a magnetically-encoded article 28. As m the prior art, when article 28 is moved past read head 50 as shown by arrow 34, magnetic information (not shown) previously encoded onto magnetic stripe 32 induces a small voltage into winding 14 ' wound on core 12' of read head 50. The low-voltage, analog output signal from core 14 ' no longer must leave the read head 10 (FIGURE 2) and be subjected to electromagnetic fields, as m the prior art. The output signal 15 is directly coupled to the input of amplifier 36' proximate winding 14' . Because winding 14' and amplifier 36' are located close together, completely within shielding housing 20', the small, analog signals are no longer exposed to extraneous electromagnetic interference. Design parameters for amplifier 36' may possibly be less demanding than for amplifier 36 (FIGURE 2) of the prior art.

An output signal 38 from amplifier 36' is provided to the input of decode electronics circuitry 44 ' . The amplified, analog signal 38 from winding 14 ' is converted to a digital output signal 40 at a standard voltage. Decode circuitry 44 ' may be implemented using application- specific integrated circuits (ASICs) or a general-purpose microprocessor m combination with programmable array logic devices, (PALs) or other gate array devices as are well known to those skilled m the art. Other ancillary passive components (not shown) such as decoupling capacitors or the like may also be provided. The output signal 40 is provided at output connections 52.

Voltage and ground signals are provided to hybrid head 50 at terminals 54 and 56, respectively. In addition, a read strobe signal is provided by decode circuitry 44 ' via output connector 58. An optional magnetic medium detected output signal 42 generated by decode circuitry 44 ' may be provided at connector 60 on head 50. The magnetic medium detected output signal 42 may be used by external equipment attached to the read head but is not a part of the instant invention.

The inclusion of amplifier 36' and decode circuitry 44' at the head 20' provides several important advantages. First, the inclusion of the amplification and decode functions close to the coil 14 ' of the read head 10 itself essentially eliminates the exposure of the low-level, analog signal 15 from the head 10 to extraneous electromagnetic fields. This allows for simplification particularly of the amplification circuitry. Because low level, external connections are eliminated, the overall reliability of the head/amplifler/decode system is improved. These read/amplify/decode functions can also be performed with a device costing substantially less than do the individual components of the prior art.

Referring now to FIGURES 4a and 4b, there are shown, generally at reference numeral 60, schematic top and rear views, respectively, of a read head assembly with decode electronics mounted on a substrate 62 attached to the back of a read head 10. Substrate 62 is configured to hold and interconnect a variety of electronic components, typically one or more ASICs 64, along with miscellaneous support circuitry (not shown) . Substrate 62 may be attached to head 10 in a variety of ways well known to those skilled in the art. An optional protective coating 67 may be placed over the assembly of head 10 and substrate 62 when required. This coating may be a potting or other suitable material . Substrate 62 is shown mounted to the rear surface of head 10. It should be obvious that substrate 62 may be attached to other surfaces of head 10 when required by a particular operating environment.

Referring now to FIGURE 5, there is shown a schematic view of the head/substrate assembly 60 with an attached cable 66. Cable 66 provides power to the circuitry on substrate 62 and also carries digital signals to and from the circuitry. One end of cable 66 may be permanently attached to substrate 62 or, in alternate embodiments, attached to substrate 62 by means of an optional connecter (not shown) . The other end of cable 66 terminates in a connector 68 adapted to plug into a socket (not shown)

Referring now to FIGURE 6, there is shown a schematic view of another alternate embodiment of the read head with decode electronics. The function of substrate 62 (FIGURE 4) has been replaced by flexible circuit assembly 70. One end 72 of flexible circuit 70 has been widened to accommodate ASICs 64 and other ancillary circuitry (not shown) and is attached to head 10. Conductors in flexible circuit 70 replace the function of cable 66 (FIGURE 5) . The distal end 74 of flexible circuit 70 is formed into a connector adapted to mate with an external socket (not shown) . The use of a flexible circuit assembly 70 improves the overall reliability at a lower component cost than that of the embodiment of FIGURES 4a, 4b and 5.

Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention.

Having thus described the invention, what is desired to be protected by Letters Patent is presented m the subsequently appended claims.

What is claimed is:

Claims

1. A magnetic read head apparatus for reading magnetically-encoded information stored on a magnetically- encoded article, comprising:

a) a housing;

b) a magnetic read head structure disposed within said housing, said magnetic read head structure comprising a core having a gap and a winding coil for generating a coil output voltage in said winding coil in response to changes in magnetic flux in said core, said changes in flux being created by the motion of said magnetic read head structure relative to said magnetically-encoded article;

c) an amplifier disposed proximate said housing, said amplifier being operatively connected to said winding coil for receiving said coil output voltage and amplifying it to generate an amplifier output voltage; and

d) decode circuitry disposed proximate said housing, said decode circuitry being operatively connected to said amplifier and adapted to receive said amplifier output voltage and to convert said amplifier output voltage to a digital signal representative of information encoded in said magnetically-encoded article.

2. The magnetic read head apparatus as recited in claim 1, wherein said decode circuitry further comprises strobe signal output means for generating a strobe signal, and wherein said conversion of said amplifier output voltage into said digital signal is at least partially controlled by said strobe signal .

3. The magnetic read head apparatus as recited in claim 1, wherein said decode circuitry further comprises magnetic medium detection means for providing a signal when said magnetically-encoded article is proximate said magnetic read head structure.

4. The magnetic read head apparatus as recited in claim 2, wherein said decode circuitry comprises at least one from the group of microprocessors, ASICs, Gate Array, Logic Array and PALs .

5. The magnetic read head apparatus as recited in claim 4, wherein said decode circuitry comprises a substrate adjacent said housing.

6. The magnetic read head apparatus as recited in claim 5, wherein said substrate comprises a flexible circuit .

7. A magnetic read head apparatus for reading magnetically-encoded information stored on a magnetically- encoded article, comprising:

a) a housing;

b) a magnetic read head disposed within said housing for generating a head output voltage in response the motion of said magnetic read head relative to said article;

c) an amplifier disposed proximate said housing, said amplifier being operatively connected to said magnetic read head for receiving said head output voltage and amplifying it to generate an amplifier output voltage; and

d) decode circuitry disposed proximate said housing, said decode circuitry being operatively connected to said amplifier and adapted to receive said amplifier output voltage and to convert said amplifier output voltage to a digital signal corresponding to information encoded in said magnetically-encoded article.

8. The magnetic read head apparatus as recited in claim 7, wherein said decode circuitry further comprises strobe signal output means for generating a strobe signal, and wherein said conversion of said amplifier output voltage into said digital signal is at least partially controlled by said strobe signal.

9. The magnetic read head apparatus as recited in claim 7, wherein said decode circuitry further comprises magnetic medium detection means for providing a magnetic document detected output signal when said magnetically- encoded article is proximate said magnetic read head structure.

10. The magnetic read head apparatus as recited in claim 8, wherein said decode circuitry comprises at least one from the group of microprocessors, ASICs, Gate Array, Logic Array and PALs .

11. The magnetic read head apparatus as recited in claim 10, wherein said decode circuitry comprises a substrate adjacent said housing.

12. The magnetic read head apparatus as recited in claim 11, wherein said substrate comprises a flexible circuit .

13. A magnetic read head apparatus for reading magnetically-encoded information stored on a magnetically- encoded article, comprising:

a) a housing;

b) a magnetic read head disposed proximate said housing for generating a head output voltage in response the motion of said magnetic read head relative to said article; and

c) decode circuitry disposed proximate said housing, said decode circuitry being operatively connected to said read head adapted to receive said head output voltage and to convert said head output voltage to a digital signal corresponding to information encoded in said magnetically-encoded article.

14. The magnetic read head apparatus as recited in claim 13, wherein said decode circuitry further comprises strobe signal output means for generating a strobe signal, and wherein said conversion of said head output voltage into said digital signal is at least partially controlled by said strobe signal .

15. The magnetic read head apparatus as recited in claim 13, wherein said decode circuitry further comprises magnetic medium detection means for providing a magnetic document detected output signal when said magnetically- encoded article is proximate said magnetic read head structure.

16. The magnetic read head apparatus as recited m claim 13, wherein said decode circuitry comprises at least one from the group of microprocessors, ASICs, Gate Array, Logic Array and PALs .

17. The magnetic read head apparatus as recited in claim 16, wherein said decode circuitry comprises a substrate adjacent said housing.

18. The magnetic read head apparatus as recited m claim 17, wherein said substrate comprises a flexible circuit .

19. A magnetic read head apparatus for reading magnetically-encoded information stored on a magnetically- encoded article, comprising:

a) a housing;

b) a magnetic read head structure disposed within said housing, said magnetic read head structure comprising a magneto-resistive element for generating a sensor output voltage in response to changes in magnetic flux proximate said magneto- resistive element, said changes in flux being created by the motion of said magnetic read head structure relative to said magnetically-encoded article;

c) an amplifier disposed within said housing, said amplifier being operatively connected to said winding coil for receiving said sensor output voltage and amplifying it to generate an amplifier output voltage; and

d) decode circuitry disposed within said housing, said decode circuitry being operatively connected to said amplifier and adapted to receive said amplifier output voltage and to convert said amplifier output voltage to a digital signal representative of information encoded in said magnetically-encoded article.

20. The magnetic read head apparatus as recited in claim 19, wherein said decode circuitry further comprises strobe signal output means for generating a strobe signal, and wherein said conversion of said head output voltage into said digital signal is at least partially controlled by said strobe signal.

21. The magnetic read head apparatus as recited in claim 19, wherein said decode circuitry further comprises magnetic medium detection means for providing a magnetic document detected output signal when said magnetically- encoded article is proximate said magnetic read head structure.

22. The magnetic read head apparatus as recited in claim 19, wherein said decode circuitry comprises at least one from the group of microprocessors, ASICs, Gate Array, Logic Array and PALs .

23. The magnetic read head apparatus as recited in claim 22, wherein said decode circuitry comprises a substrate adjacent said housing.

24. The magnetic read head apparatus as recited in claim 23, wherein said substrate comprises a flexible circuit .

AMENDED CLAIMS

[received by the International Bureau on 24 August 2000 (24.08.00); original claims 1, 7 and 19 amended; remaining claims unchanged (3 pages)]

1. A magnetic read head, amplifying, and decoding apparatus for reading magnetically-encoded information stored on a magnetically-encoded article, said amplifying and decoding apparatus being proximate sa d magnetic read head apparatus to reduce interference with its signal, sa d magnetic read head, amplifying, and decoding apparatus comprising:

a) a housing for providing shielding for components;

b) a magnetic read heaα structure disposed within said housing, said magnetic read head structure comprising a core having a gap and a winding coil for generating a coil output voltage m said winding coil in response to changes in magnetic flux in said core, said changes m flux being created by the motion of said magnetic read head structure relative to said magnetically-encoded article;

c) an amplifier disposed proximate said housing and said magnetic read nead, said amplifier being operatively connected to said winding coil for receiving said coil output voltage and amplifying it to generate an amplifier output voltage; and

d) decode circuitry disposed proximate said housing, said magnetic read head and said amplifier, said decode circuitry being operatively connected to said amplifier and adapted to receive said amplifier output voltage and to convert said amplifier output voltage to a digital signal representative of information encoded m said magnetically-encodeα article.

7. A magnetic read head, amplifying, and decoding apparatus for reading magnetically-encoded information stored on a magnetically-encoded article, sa d amplifying and decoding apparatus being proximate said magnetic read head to reduce interference with its signal, said magnetic read head, amplifying, and decoding apparatus comprising:

a) a housing for providing shielding for components;

c) an amplifier disposed [proximate] within said housing and proximate said magnetic read head, said amplifier being operatively connected to said magnetic read head for receiving said head output voltage and amplifying it to generate an amplifier output voltage; and

d) decode circuitry disposed [proximate] within said nousmg anc proximate said magnetic read head ana said amplifier, said αecode circuitry being operatively connected to said amplifier and adapted to receive said amplifier output voltage and to convert said amplifier output voltage to a digital signal corresponding to information encoded in said magnetically-encoded article.

8, The magnetic read nead apparatus as recited m claim 7, wherein said decode circuitry further comprises strope signal output means for generating a strobe signal, and wherein said conversion of said amplifier output voltage into said digital signal is at least partially controlled by said strobe signal.

19. A magne_tic read head, amplif^yin^g, and decodin^g apparatus for reading magnetically-encoded information s_tored on a magnetically-encoded article, said am^plif^yin^g and decoding apparatus being proximate said ma^gnetic read head to reduce interference with its si^gnal^, said ma^gnetic read head, amplifying, and decodin^g a^pparatus comprising:

a₎ a housing fcr providing shieldin^g for com^ponents^,-

b) a magne_tic read head structure disposed withnm said housing, said magnetic read head structure comprising a magneto-resistive element for generating a sensor output voltage in response to changes in magnetic flux proximate said magneto- resistive element, said changes in flux being created by the motion of said magnetic read head structure relative to said magnetically-encoded article;

c₎ an amplifier disposed within said housing and proxima_te said read head, said amplifier being opera_tively connected to said winding coil for receiving said sensor output voltage and amplifying it to generate an amplifier output voltage; ana

d₎ decode circuitry disposed within said housing and proxima_te said read head and am^plifier^, said decode circuitry being operatively connected to said amplifier and adapted to receive said amplifier output voltage and to convert said amplifier ci_tput voltage to a digital signal represen_ta_tive of information encoded in said magnetically-encoded article.