JPH0457203A - Magnetic data reader - Google Patents

Abstract

PURPOSE:To exactly read data by deciding the length of an odd-number magnetic domain based on the average value of the odd-number domain and deciding the length of an even-number magnetic domain based on the average value of the even-number domain. CONSTITUTION:When reading magnetic data 1 expressed by the length of the magnetic domain, first of all, an odd-number domain average value calculating means 2 and an even-number domain average value calculating means 3 calculate the average values of the lengths of the odd-number and even-number domains. By using these average values, a length deciding means 4 decides the length of the magnetic data. Namely, when deciding an odd-number domain, the average value of the odd-number domain is used and when deciding an even-number domain 1e, the average value of the even-number domain is used. Thus, even when the length is different in the magnetic domain magnetized in a regular direction and the magnetic domain magnetized oppositely to the magnetic domain as mentioned above, reading is enabled axactly and even when there is jitter in the middle of reading, there is no error.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a magnetic data reading device for reading magnetic data recorded by an FM system.

(b) Conventional technology MFM (Modified
Frequency? There is a method called Iodulation). In this method, sections where the magnetic recording medium is magnetized in the writing (reading) direction (forward direction) and sections where it is magnetized in the opposite direction (reverse direction) are provided alternately, and "J+" u □ is created depending on the length of the section. This is a method of expressing data of n. In other words, the magnetization direction is reversed every length corresponding to one bit, and if there is further reversal of the magnetization direction within that bit, the focus will be "'1°", and the magnetization direction will be reversed within that bit. If it is not present, it is expressed as "'0".

Moreover, the magnetic data recorded in this way can be read by the following method. The magnetic head is moved relative to the magnetic recording section, and the length of the magnetized section is determined from the change in the induced electromotive force generated in the magnetic head. The data is reproduced based on the length of the determined magnetization section. In other words, as mentioned above, a bit in which the magnetization direction is reversed is 1, and a bit without is ``0'', so the length of the two magnetization sections that constitute ``1'' constitutes ``O''. Therefore, depending on whether or not there is a reversal of the magnetization direction within the length of 1 bit, "1゛II Q +"
It is possible to distinguish between By the way, when reading, a 1-bit length standard is required. This length standard was based on the length of the previous 1 bit in order to cancel the effects of changes in reading speed, etc.

(C) Problems to be Solved by the Invention By the way, magnetic cards (magnetic recording media) used in prepaid cards and the like are unidirectionally magnetized at the time of manufacture (see arrows in FIG. 6). In order to write magnetic data to this magnetic card, the direction of magnetization is changed by moving the magnetic head relative to the magnetic recording medium and changing the direction of the current passing through the magnetic head, thereby forming a magnetized section. I have to. However, even if the current in the magnetic head is reversed by exactly the same length, the direction of magnetization of the magnetic card is not exactly reversed (see FIG. 6).

This is because in order to magnetize in the opposite direction to the direction in which it was previously magnetized, a stronger current is required than in the same direction.

When a long/short variation occurs in the magnetization section in this way, the size of one bit #fr is determined based on the previous bit as described above.
The method of determining whether the reversal of the magnetization direction is at the break of one focus or within a bit may cause an error. Furthermore, if jitter occurs during reading, subsequent bit reading becomes inaccurate.

An object of the present invention is to provide a magnetic data reading device that solves the above problem by separately averaging the lengths of odd-numbered magnetization sections and even-numbered magnetization sections and using the lengths as a criterion for determining the bit length. purpose.

(d) Means for Solving the Problems The present invention provides a magnetic data reading device that reads magnetic data expressed by the lengths of a plurality of magnetization sections formed by reversing the magnetization direction. an odd-numbered section average value calculating means for calculating an odd-numbered section average value that is an average value of the length of the odd-numbered magnetization sections from the beginning; an even-numbered interval average value calculating means for calculating an even-numbered interval average value, which is an average value of the magnetization; and a length determination means for determining the length based on the average value of the even-numbered section when the magnetization section is an even-numbered one from the beginning.

(e) Operation FIG. 1 is a block diagram of the present invention. When the magnetic data 1 expressed by the length of the magnetization section is read, first, the odd number section average value calculation means 2 and the even number section average value calculation means 3 are read.
Accordingly, the average value of the lengths of the odd-numbered sections and even-numbered sections (odd-numbered section average value, even-numbered section average value) is calculated. The length determining means 4 uses this average value to determine the length of the magnetic data. That is, when determining the odd numbered section 1d, the odd numbered section average value is used, and when determining the even numbered section 1e, the even numbered section average value is used. By doing this, accurate reading can be performed even when the lengths of the magnetized section magnetized in the forward direction and the magnetized section magnetized in the opposite direction are different, and it is also possible to obtain accurate readings even if there is jitter during reading. An error will no longer occur even in this case.

(f) Embodiment FIG. 2 is a block diagram of a magnetic data reading device according to an embodiment of the present invention. The magnetic head 3o is provided in a card transport device (not shown) and faces a magnetic recording medium transported by the card transport device. This magnetic recording head 3o is connected to an amplifier 31. The amplifier 31 amplifies the detection signal input from the magnetic head 30 and inputs it to the peel detection circuit 32. Peak detection circuit 3
2 differentiates the input detection signal and inputs the differentiated signal to the signal detection circuit 33. The signal detection circuit 33 is a circuit that shapes the input differential signal into waveforms (binarizes it) and reproduces the recorded content (the length of the f6i section) of the magnetic recording medium.

The reproduced recorded content is input to the CPU 34. CPU
34, while reading the recorded contents inputted, the length of each magnetization section is read by the clock signal inputted from the counting circuit 35, and this data is stored in the memory 36. The memory 36 is provided with storage areas as shown in FIG. 2, including a read data storage area for storing read data. The CPU 34 reads all recorded contents of the magnetic recording medium and then reproduces the data.

FIG. 3 is a diagram showing a partial configuration of the memory 34. As shown in FIG. 1
00 is a counter area. In this area, the number of magnetized sections of the magnetic recording medium that has been read is counted. 101
．． LO2 is an odd section counter area and an even section counter area.

The number of odd-numbered magnetization sections and the number of even-numbered magnetization sections of the synchronization signal area 21 are counted and amplified in these areas. 103 and 104 are an odd number interval calculation area and an even number interval calculation area. In these areas, the lengths of the odd-numbered magnetization sections and the lengths of the even-numbered magnetization sections are accumulated and stored. Further, 105 and 106 are an odd number section average area and an even number section average area. The odd-numbered interval average area 105 contains a value obtained by dividing the integrated value of the odd-numbered interval calculation area 103 by the value of the odd-numbered counter area 101 (
The even-numbered interval average value) is stored, and the even-numbered average area 106 stores a value obtained by dividing the integrated value of the even-numbered calculation area 104 by the numerical value of the even-numbered counter area 102 (even-numbered interval average value). That is, the average length of one odd-numbered bit (more precisely, the one-bit length used as a reference when determining an odd-numbered magnetization section) and the average length of one even-numbered bit are stored. Furthermore, 108 is a read data storage area. In this area, the length read data of each magnetization section of the data input from the signal detection circuit 33 is sequentially stored from the beginning. Further, i07 is a final address storage area. In this area, the address from the beginning of the read data storage area 108 to which the read data has been written is stored.

Here, FIG. 5 shows a configuration diagram of a magnetic card read by this magnetic data reading device. A magnetic recording section (magnetic stripe) 20 is formed on the magnetic card 10, and in this magnetic recording section, data is recorded in the following format: 21 - synchronization signal section 22 - preamble section 23 - Data body section 24 - Postamble section 25 - Synchronization signal section In the synchronization signal section 21.25, data of "0" is continuously recorded and has a function of providing a reference clock when reading.Preamble section 22. Data “1” is continuously recorded in the postamble part 24, indicating that it is before and after the data main part 3.The data main part 23 contains the card number, authentication number, etc. In the magnetic data reading device of the present invention, by reading the "0" data of the synchronization signal section 21, the average value of the 1-bit length is determined.

FIG. 4 is a flow chart showing the operation of the CPU 34. When read data (magnetization section data) is input from the signal detection circuit 33, the memory area shown in FIG. Measure (n
2). This length data is read and the data storage area 10
8 (n3) and the address of the read data storage area is added (n4). When this operation is completed for all read data, the process advances from n5 to 06.

At n6, the final address of the area where the read data is stored is stored in the final address register 107. At nl, 1 is added to the counter 100, and it is determined whether the content is an odd number or an even number (n8). If the number is odd, add 1 to the odd section counter 101 (ri9),
The length of the read data indicated by the count value is accumulated in the odd-numbered interval calculation area 103 (nlo). If the content of the counter 100 is an even number, 1 is added to the even interval counter 102 (n9'), and the length of the read data indicated by the count value is integrated in the even interval calculation area 104 (n10). '). Next, the address of the read data storage area is added (nil). In order to repeat this operation a predetermined number of times, the process returns from rh12 to n7. After performing the above operations on the data of the synchronization signal section 21, the process proceeds to nL3 based on the determination at n12. In ni3, the average value of the odd-numbered 1 bit is calculated using the odd-numbered interval counter 101 and the stored contents of the odd-numbered interval calculation area 103, and is stored in the odd-numbered interval average area 105. Next, even number interval counter 1
02 and the memory contents of the even number interval calculation area 104, the average value of the even numbered 1 bit is calculated and the even number interval average area 106
(n14), then after resetting the counter 100 (n i 5 ), n 16 to rr 2
Execute operation 1. At n16, 1 is added to the counter 100, and it is determined whether the content of the counter 100 is an odd number or an even number. In case of odd number, odd number interval average area L
“1′°,” “0” based on the contents stored in O5
(nL8), and if it is an even number, based on the contents stored in the even number interval average area 106, "1 pa,
Make a judgment of "O" (n19).Increment the data address in n20, and return to n16 from n21 until the judgment of all data is completed.When the judgment of all data is completed, the book ends with the judgment of n21. In the embodiment, the odd number and even number of the read synchronization signals are counted by counters 101 and 1.
02, but if the number of synchronization signals to be read first has been determined, the odd number and even number can be stored without counting.

Furthermore, the section read in order to obtain the average value is not limited to the synchronization signal section 21.

(According to the magnetic data reading device of this invention, as described above,
By determining the length of odd-numbered magnetization sections based on the odd-numbered section average value, and determining the length of even-numbered magnetization sections based on the even-numbered section average value, forward magnetization and Even if the length differs due to magnetization in the opposite direction (peak shift), data can be read accurately. Further, even if jitter occurs during reading, no error will occur in subsequent bit reading.

FIG. 5 is a diagram showing the configuration of a general magnetic card, and FIG. 6 is a diagram showing the relationship between write signals and magnetization of a magnetic recording medium.

Magnetic data, lb, ld - odd number interval, c, ie-even interval, odd number interval average value calculation means; even number interval average value calculation means; length/shortness determination means; Magnetic stripe, 21-sync signal section.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of the present invention. Fig. 2 is a block diagram of a magnetic data reading device according to an embodiment of the present invention, Fig. 3 is a partial configuration diagram of the memory of the magnetic data reading device, and Fig. 4 shows the operation of the CPU of the magnetic data reading device. FIG.

Claims (1)

[Claims] (1) In a magnetic data reading device that reads magnetic data expressed by the length of a plurality of magnetization sections formed by reversal of the magnetization direction, for a part of the plurality of magnetization sections, the length of an odd-numbered magnetization section from the beginning is determined. an odd-numbered section average value calculating means for calculating an odd-numbered section average value that is the average value of the magnetization; The even-numbered interval average value calculation means to determine the length of the magnetization interval is determined based on the odd-numbered interval average value when the magnetization interval is an odd-numbered one from the beginning, and the magnetization interval is an even-numbered one from the beginning. A magnetic data reading device comprising: a length determination means based on the average value of the even numbered intervals when