AU616490B2 - Magnetic record medium and method of recording and reproducing security information on and from the same - Google Patents
Magnetic record medium and method of recording and reproducing security information on and from the same Download PDFInfo
- Publication number
- AU616490B2 AU616490B2 AU31646/89A AU3164689A AU616490B2 AU 616490 B2 AU616490 B2 AU 616490B2 AU 31646/89 A AU31646/89 A AU 31646/89A AU 3164689 A AU3164689 A AU 3164689A AU 616490 B2 AU616490 B2 AU 616490B2
- Authority
- AU
- Australia
- Prior art keywords
- changes
- security information
- record medium
- information
- magnetic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Ceased
Links
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
- G11B5/09—Digital recording
-
- G—PHYSICS
- G07—CHECKING-DEVICES
- G07F—COIN-FREED OR LIKE APPARATUS
- G07F7/00—Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus
- G07F7/08—Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus by coded identity card or credit card or other personal identification means
- G07F7/086—Mechanisms actuated by objects other than coins to free or to actuate vending, hiring, coin or paper currency dispensing or refunding apparatus by coded identity card or credit card or other personal identification means by passive credit-cards adapted therefor, e.g. constructive particularities to avoid counterfeiting, e.g. by inclusion of a physical or chemical security-layer
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
- G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
- G06K7/08—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes
- G06K7/082—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes using inductive or magnetic sensors
- G06K7/083—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes using inductive or magnetic sensors inductive
- G06K7/084—Methods or arrangements for sensing record carriers, e.g. for reading patterns by means detecting the change of an electrostatic or magnetic field, e.g. by detecting change of capacitance between electrodes using inductive or magnetic sensors inductive sensing magnetic material by relative movement detecting flux changes without altering its magnetised state
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/14—Digital recording or reproducing using self-clocking codes
- G11B20/1403—Digital recording or reproducing using self-clocking codes characterised by the use of two levels
- G11B20/1407—Digital recording or reproducing using self-clocking codes characterised by the use of two levels code representation depending on a single bit, i.e. where a one is always represented by a first code symbol while a zero is always represented by a second code symbol
- G11B20/1419—Digital recording or reproducing using self-clocking codes characterised by the use of two levels code representation depending on a single bit, i.e. where a one is always represented by a first code symbol while a zero is always represented by a second code symbol to or from biphase level coding, i.e. to or from codes where a one is coded as a transition from a high to a low level during the middle of a bit cell and a zero is encoded as a transition from a low to a high level during the middle of a bit cell or vice versa, e.g. split phase code, Manchester code conversion to or from biphase space or mark coding, i.e. to or from codes where there is a transition at the beginning of every bit cell and a one has no second transition and a zero has a second transition one half of a bit period later or vice versa, e.g. double frequency code, FM code
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/14—Digital recording or reproducing using self-clocking codes
- G11B20/1403—Digital recording or reproducing using self-clocking codes characterised by the use of two levels
- G11B20/1423—Code representation depending on subsequent bits, e.g. delay modulation, double density code, Miller code
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Artificial Intelligence (AREA)
- Computer Vision & Pattern Recognition (AREA)
- Theoretical Computer Science (AREA)
- Computer Security & Cryptography (AREA)
- Signal Processing For Digital Recording And Reproducing (AREA)
- Digital Magnetic Recording (AREA)
- Recording Or Reproducing By Magnetic Means (AREA)
Description
616490 1 COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION NAME ADDRESS OF APPLICANT: Kyodo Printing Co., Ltd.
14-12 Koishikawa 4-chome, Bunkyo-ku Tokyo Japan NAME(S) OF INVENTOR(S): Minoru FUJITA 9 ADDRESS FOR SERVICE: DAVIES COLLISON Patent Attorneys 1 Little Collins Street, Melbourne, 3000.
COMPLETE SPECIFICATION FOR THE INVENTION ENTITLED: Magnetic record medium and method of recording and reproducing security information on and from the same The following statement is a full description of this invention, including the best method of performing it known to me/us:- I x i4 1A BACKGROUND OF THE INVENTION i. Field of the Invention This invention relates to a magnetic record medium 2. Description of Prior Art C' An exemplary one of conventional methods of recording information on a magnetic record medium is illustrated in a waveform diagram of FIG. 4.
,,Referring to FIG. 4, digital magnetic recording for S recording digital information on a magnetic record medium I L is effected by flowing write current iw in the form of pulses i having an absolute value greater than Is through a magnetic 0 head where Is or -Is is an electric current necessary to attain saturation magnetization Ms or -Ms, respectively, of a record medium.
With the record medium, the magnetization condition thereof exhibits steep changes between Ms and -Ms in accordance with information. Accordingly, if the record medium is scanned by the magnetic head to read out the recorded information on the record medium, then a read signal can be obtained the voltage of which is reversed in -a T 0 1 taw r r KI- -2polarity at each point at which the magnetization condition is changed in accordance with a changing direction of the magnetization condition as seen from a waveform shown in Fig. 4.
In order to prevent production of a counterfeit magnetic medium or tampering with a true magnetic medium, naturally it is necessary to keep a true/false determining method secret, but in addition, it is necessary to discourage a false user producing a counterfeit magnetic medium. In this regard, a conventional magnetic record medium is not satisfactory in security since it depends on such common digital recording method as described above.
SUMMARY O1 THE INVENTION According to the present invention there is provided magnetic record medium having security information, characterized in that said security information is recorded with moderate changes and steep changes in magnetization, wherein the steep changes are effected either from negative polarity to positive polarity or from positive polarity to negative polarity and represent a predetermined state of the security information, S.said steep changes producing a relatively large change in a read-out signal and said 20 moderate changes producing in comparison a negligible change in said read-out i signal.
The present invention further provides magnetic record medium having security 4 information, characterized in that said security information is recorded with moderatel 25 changes and steep changes in magnetization, wherein said security information comprises alternate portions, one portion in which the steep changes are effected from negative polarity to positive polarity and another portion in which the steep changes are effected from positive polarity to negative polarity, said steep changes representing a predetermined state of the security information, and said steep changes producing a relatively large change in a read-out signal and said moderate changes producing in comparison a negligible change in said read-out signal.
AL
910813,gcpdat.085,31646.c,2 f.
kPy O3 -3- The present invention also provides a information reproducing method for reproducing information recorded on a magnetic medium as described above characterised in that such security information is reproduced by a detecting means which has a differentiating function.
The present invention further provides an information recording method wherein, using a magnetic writing means for writing information on a magnetic record medium, security information is recorded on a magnetic record medium with moderate changes and steep changes of write current for driving said magnetic writing means, wherein the steep changes are effected either from negative polarity to positive polarity or from positive polarity to negative polarity and represent a predetermined state of the security information, said steep changes producing a relatively large change in a read-out signal and said moderate changes producing in comparison a negligible change in said read-out signal.
The present invention also provides an information recording method wherein, a .using a magnetic writing means for writing information on a magnetic record medium, security information is recorded on a magnetic record medium with moderate changes 4 and steep changes of write current for driving said magnetic writing means, wherein 20 said magnetic writing means is driven alternately in a first manner in which write current is changed steeply from negative polarity to positive polarity and in a second manner in which write current is changed steeply from positive polarity to negative polarity, said steep changes representing a predetermined state of the security information, and said steep changes producing a relatively large change in a read-out 25 signal and said moderate changes producing in comparison a negligible change in said read-out signal.
BRIEF DESCRIPTION OF THE DRAWINGS Preferred embodiments of the present invention are hereinafter described, by way of example only, with reference to the accompanying drawings, wherein: c FIG. 1(A) is a schematic view illustrating general construction of a magnetic 0 910813,gcpdaL.05,31646.c,3 3a head and a magnetic record medium, and FIG. 1(B) is a schematic waveform diagram illustrating an information recording method and an information reproducing method according to a first preferred embodiment of the present i 1 ti
A
1 L 'i r E 3a 1 !head and a magnetic record medium, and *.FIG. 1(B) is a schematic waveform diagram illustrating an information 4' .I recording method and an information reproducing method according to a first prefered embodiment of the present
S|
1|
I;
i i 1 oo i t I clrl Ir ;*i n .o t c ;-r y s 1 1 i r l t 4 1 4" i 910813,gcpdat.085,316464 invention; FIG. 2 is a block diagram illustrating general construction of a reproducing device to which the present invention is applied; FIG. 3 is a schematic waveform diagram illustrating an information recording and reproducing method according to a second embodiment of the present invention; and FIG. 4 is a schematic waveform diagram illustrating a conventional method of recording information on a magnetic record medium.
DETAILED DESCRIPTION OF THE INVENTION In the following, an embodiment of the present invention will be described in detail with reference to the drawings.
t 4 Referring first to FIG. there is illustrated schematic construction of a magnetic head and a magnetic *t a4 record medium. The magnetic head is generally denoted at 1 and adapted to scan the record medium denoted at 2 on a base plate 3 to effect recording or reproduction of information oon or from the record medium 2 in such a manner as described below. It is to be noted that digital recording based on \I the NRZI method is employed here.
Writing of Information Where information is, for example, "1011" as shown in 1$ C :i 1 FIG. write current iw to be supplied to the magnetic head 1 is changed steeply from +Is to -Is only when the i Ai q r contents of information to be written is but such write current iw is changed moderately in any other instance.
Consequently, the magnetization condition M of the record medium 2 presents a steep change from +Ms to -Ms only at each in accordance with such write current iw but presents a moderate change at any other position of the record medium 2.
Reproduction of Information I "J!When the record medium 2 on which the information "1011" r is recorded in this manner is scanned by the magnetic head 1, as the read-out voltage er induced in the magnetic head 1 has a proportional relationship to a change in magnetic flux, a pulse appears at a position of the read-out voltage er Swhere the magnetization condition M on the record medium 2 exhibits a steep change. In particular, the read-out voltage er presents a pulse of a great magnitude on the side at a position of the information at which the magnetization 4 a 4 Scondition M changes steeply, but presents a little deviation to the side at any position where the magnetization condition M presents a moderate change.
Accordingly, if a suitable slice level es is set, then a pulse el corresponding to the information can be reproduced, and a pulse eO corresponding to the information can be reproduced from such pulses el and clock pulses ec.
Further, if a suitable error w,tection level ex is set Y on the side of the read-out voltage er, then security 1 -I~s 6 checking can be made. In particular, if a magnetic record medium is used on which information is recorded not based on such a recording method as employed in the present embodiment but based on a common recording method, then the read-out voltage will change alternately between the positive and negative values. Consequently, such false magnetic record 0 medium is detected with reference to the error detection *000 ooo level ex, and it is possible to make use of such false 0000 °o magnetic record medium impossible. Accordingly, if the 9000 recording method as in the embodiment described above is applied to recording of security information, then the security of a magnetic card or the like can be improved.
o. 0 It is to be noted that while the NRZI method is used as a digital recording method in the embodiment described above, the digital recording method is not limited to this and may be some other digital recording method such as the NRZ, FM, PM or MFM method.
,4 Referring now to FIG. 2, there is shown general construction of a reproducing device according to the present invention. The reproducing device shown is principally applied for a self-clockable recording method and includes a driver 4 by which the magnetic head 1 is driven. A read-out signal of the magnetic head 1 is delivered to a binary digitizing and error detecting circuit 5, in which a pulse i el is extracted using the slice level es and parity check is effected using the error detection level ex as described
IL
7 hereinabove.
The binary digitized pulse signal el is delivered to a clock reproducing circuit 6 by which clock pulses ec are reproduced. Then, a demodulating circuit 7 reproduces the information recorded on the record medium from the signals el and ec.
It is to be noted that, where a recording method which S is not self-clockable is employed, clocks may be read out 4 separately by means of another magnetic head 8.
I
Referring now to FIG. 3, there is illustrated a i recording and reproducing method according to a second embodiment of the present invention. According to the method, f security information is recorded such that portions in which write current iw is changed steeply from +Is to -Is and i portion in which write current iw is changed steeply from -Is to +Is are included in a suitably mixed manner. With the method, the security can be improved further.
0 Since the present invention has such a construction as described hereinabove, the following effects can be attained. 4 As distinct from such a read-out voltage as based on a conventional digital recording method wherein the polarity is alternately reversed, a read-out voltage having a fixed i one polarity between the positive and negative polarities can be obtained, and accordingly, also the reversal in polarity can be utilized as security information. Accordingly, the security can be further improved.
Claims (1)
- 8- THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. Magnetic record medium having security information, characterized in that said security information is recorded with moderate changes and steep changes in magnetization, wherein the steep changes are effected either from negative polarity to positive polarity or from positive polarity to negative polarity and represent a predetermined state of the security information, said steep changes producing a relatively large change in a read-out signal and said moderate changes producing in comparison a negligible change in said read-out signal. 2. Magnetic record medium having security information, characterized in that said security information is recorded with moderate changes and steep changes in magnetization, wherein said security information comprises alternate portions, one portion in which the steep changes are effected from negative polarity to positive polarity and another portion in which the steep changes are effected from positive polarity to negative polarity, said steep changes representing a predetermined state of the security information, and said steep changes producing a relatively large change in a read-out signal and said moderate changes producing in comparison a negligible S•change in said read-out signal. 3. An information reproducing method for reproducing such security information recorded on the magnetic record medium as claimed in claim 1 or 2, characterized in that such security information is reproduced by a detecting means which has a 4 differentiating function. 4. An information recording method wherein, using a magnetic writing means for *writing information on a magnetic record medium, security information is recorded on a magnetic record medium with moderate changes and steep changes of write current for driving said magnetic writing means, wherein the steep changes are effected either from negative polarity to positive polarity or from positive polarity to negative polarity and represent a predetermined state of the security information, said i steep changes producing a relatively large change in a read-out signal and said 5)910813,gcpdat.085,31646.c,8 O! -9- moderate changes producing in comparison a negligible change in said read-out signal. An information recording method wherein, using a magnetic writing means for writing information on a magnetic record medium, security information is recorded on a magnetic record medium with moderate changes and steep changes of write current for driving said magnetic writing means, wherein said magnetic writing means is driven alternately in a first manner in which write current is changed steeply from negative polarity to positive polarity and in a second manner in which write current is changed steeply from positive polarity to negative polarity, said steep changes representing a predetermined state of the security information, and said steep changes producing a relatively large change in a read-out signal and said moderate changes P producing in comparison a negligible change in said read-out signal. 6. A magnetic record medium substantially as hereinbefore described with reference to the accompanying drawings. 7. An information reproducing method substantially as hereinbefore described with reference to the accompanying drawings. 8. An information recording method substantially as hereinbefore described with reference to the accompanying drawings. a 1a DATED this 12th day of July, 1991. KYODO PRINTING CO., LTD. By its Patent Attorneys DAVIES COLLISON S 910813,gcpdat.085,31646.c,9 YDi-o sinal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63074675A JPH01248301A (en) | 1988-03-30 | 1988-03-30 | Method for recording and reproducing magnetic recording medium and its security information |
| JP63-74675 | 1988-03-30 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| AU3164689A AU3164689A (en) | 1989-10-05 |
| AU616490B2 true AU616490B2 (en) | 1991-10-31 |
Family
ID=13554041
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| AU31646/89A Ceased AU616490B2 (en) | 1988-03-30 | 1989-03-23 | Magnetic record medium and method of recording and reproducing security information on and from the same |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPH01248301A (en) |
| KR (1) | KR930001701B1 (en) |
| AU (1) | AU616490B2 (en) |
| GB (1) | GB2217096B (en) |
| HK (1) | HK106993A (en) |
| SG (1) | SG27393G (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2367182B (en) | 2000-09-20 | 2004-05-26 | Hewlett Packard Co | Improvements in and relating to data protection |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4219851A (en) * | 1978-11-24 | 1980-08-26 | Honeywell Information Systems Inc. | Group coded recording data recovery system |
| US4342054A (en) * | 1979-06-06 | 1982-07-27 | Nakamichi Corporation | Information read device |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5942617A (en) * | 1982-08-31 | 1984-03-09 | Sansui Electric Co | Magnetic recording and reproducing system |
| JPS5960713A (en) * | 1982-09-30 | 1984-04-06 | Sansui Electric Co | Magnetic recording and reproducing system |
-
1988
- 1988-03-30 JP JP63074675A patent/JPH01248301A/en active Pending
-
1989
- 1989-03-22 GB GB8906646A patent/GB2217096B/en not_active Expired - Lifetime
- 1989-03-23 AU AU31646/89A patent/AU616490B2/en not_active Ceased
- 1989-03-28 KR KR1019890003902A patent/KR930001701B1/en not_active IP Right Cessation
-
1993
- 1993-03-15 SG SG273/93A patent/SG27393G/en unknown
- 1993-10-14 HK HK1069/93A patent/HK106993A/en not_active IP Right Cessation
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4219851A (en) * | 1978-11-24 | 1980-08-26 | Honeywell Information Systems Inc. | Group coded recording data recovery system |
| US4342054A (en) * | 1979-06-06 | 1982-07-27 | Nakamichi Corporation | Information read device |
Also Published As
| Publication number | Publication date |
|---|---|
| HK106993A (en) | 1993-10-22 |
| GB8906646D0 (en) | 1989-05-04 |
| KR930001701B1 (en) | 1993-03-11 |
| SG27393G (en) | 1993-05-21 |
| GB2217096B (en) | 1992-01-22 |
| GB2217096A (en) | 1989-10-18 |
| JPH01248301A (en) | 1989-10-03 |
| AU3164689A (en) | 1989-10-05 |
| KR890015243A (en) | 1989-10-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MK14 | Patent ceased section 143(a) (annual fees not paid) or expired |