JPH0775108B2 - Magnetic recording medium reader - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Field of Industrial Application) The present invention relates to a magnetic recording medium reading device for reading magnetic data written on, for example, an ID card.

(Prior Art) The magnetic data of the ID card is written by the FM magnetic recording method as shown in FIG. In this method, by changing the frequency of the recording signal, the magnetization is inverted once for the "0" data and recorded, and the magnetization is inverted twice for the "1" data. In order to read this magnetic recording data, "1" and "0" are determined according to the number of times of magnetization reversal and its time width. This FM magnetic recording method has a drawback that when the transport speed of the magnetic recording medium fluctuates for a certain time or longer, the magnetization reversal time also fluctuates and the data discrimination between "1" and "0" is mistaken.

(Problems to be Solved by the Invention) Conventionally, magnetic data may be erroneously discriminated due to variations in the transport speed of the magnetic recording medium. Even if a constant speed feed mechanism is provided, the card feed speed cannot be directly controlled, and the rotation of the feed motor is indirect, which is an indirect method, so accurate constant speed feed cannot be performed. It was

Therefore, it is an object of the present invention to provide a highly reliable magnetic recording medium reading device that follows a variation in the transport speed and makes data determination without error.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention has a magnetization reversal signal obtained by A / D converting a reproduction signal from a read magnetic head during reading and carrying of a magnetic recording medium. The inversion time is measured and stored, and the data is sequentially discriminated according to the interval of the magnetization inversion time stored in the post-processing after the completion of conveyance. At that time, the data determination time of the determination bit is always moved based on the magnetization reversal time per bit of the previous determination bit, and the determination standard is sequentially moved to change, so that the determination according to the variation of the magnetization reversal time with respect to the speed variation at that time can be performed. In addition, the noise determination can be performed when the magnetization reversal time of the determination bit is shorter than the specified time.

(Operation) As a result, the signal and noise can be separated. Also, since the judgment standard changes following the magnetization reversal time fluctuation, that is, the carrier speed fluctuation, there is no influence of speed fluctuation and noise, and data discrimination is always correct. it can.

(Example) Hereinafter, one example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a magnetic card reader that carries an ID card and reads magnetic information. In the figure, reference numeral 1 is a conveying path for sandwiching and conveying the ID card K between a plurality of pairs of drive rollers 4 and pinch rollers 5. Each drive roller 4 is driven by the drive force of the pulse motor 6 being transmitted via the belt 7. Reference numeral 2 is a detector for detecting the ID card K conveyed in the direction of arrow a in the figure, which is for the timing of the read magnetic head 4. Reference numeral 8 is a reading circuit for making data determination from the electric signal of the magnetic head.

FIG. 2 is a block diagram showing a specific configuration of the reading circuit 8. Reference numeral 9 is an A / D converter for converting a reproduction electric signal of the reading magnetic head 3 into a digital signal. can get. The output is sent to the magnetization reversal measurement unit 10, and the magnetization reversal time is measured based on the sampling by the clock generator 11. Reference numeral 12 is a storage device that sequentially stores the time data from the magnetization reversal measurement unit 10.

Reference numeral 13 denotes an information processing unit that determines data based on the magnetization reversal time data stored in the storage device. In particular, this information processing unit is configured to always compare and determine the length of the current time data with reference to the immediately preceding time data.

Next, the operation of the above-described component device will be described with reference to the read waveform and inversion time chart of FIG.

In FIG. 1, the pulse motor 6 is started, and the drive roller 4 is rotated via the belt 7, whereby the ID card K is sandwiched between the drive roller 4 and the pinch roller 5 and conveyed in the direction of the arrow a. When reaches the detector 2, the reading circuit 8 becomes operable. When the reading magnetic head 3 scans the stripe surface containing the magnetic data of the ID card K, a reproduction electric signal as shown in FIG. 3 (a) is obtained, and this signal is obtained by the A / D converter 9 in FIG. Send to. The A / D converter 9 sends the magnetization reversal output of FIG. 3B converted into a digital signal to the magnetization reversal measurement unit 10. FIG. 3 (c) is a count clock for measuring the magnetization reversal interval with the reference clock signal from the clock generator. The magnetization reversal output as shown in FIG. 3B supplied to the magnetization reversal measurement unit 10 of FIG. 2 is counted here by the reference clock (c) for the magnetization reversal time of the “H” level and the “L” level. To do. The counted magnetization reversal times are sequentially stored in the RAM (random access memory) of the storage unit 12 shown in FIG. 2 in the form shown in FIG.
This operation is continued until the ID card K passes through the reading magnetic head 3 in FIG. 1 and passes through the detector 2. At the time when the ID card K passes, the pulse motor 6 is stopped and the reading operation is completed. Next, the information processing unit 10 sequentially performs bit determination from the head address of the RAM storing the magnetization reversal time of FIG. The first data Dn at the start address of the RAM is used as the data determination reference Tn and this data is set to "0" (according to the data format of the ID card, "0" is written as the time signal before the start code STX. Hid judgment is performed sequentially from the next data D ^0, but Dn +
1 is discriminated by the discrimination criterion Tn of the previous data. The bit judgment is, for example, “0” if the data Dn + 1 is 3/4 or more with respect to the reference value Tn, and the data Dn + 1 is less than 3/4 and Dn + 2.
Is less than 3/4, it is judged as "1". In addition, at that time, if there is a reversal time of 1/4 or less of the criterion Tn (for example, the third
(T ² inversion time in figure (e)) It is regarded as noise and invalidated.
Inversion time (Dn + 1) + which combines the subsequent data and noise
(Dn + 2) + (Dn + 3) is the bit time to be judged. If the judged data is "0", the data value becomes the next data judgment criterion T. If the judged data is "1", the 1-bit data time of the next data is the time of the next data. It becomes the criterion T. Data discrimination is performed by changing the data discrimination standard by the above processing.

In this way, the change in the ID card transport speed is replaced with the change in the bit inversion time, the judgment criterion is changed according to the change in speed, and the data discrimination is performed after reading all recording surfaces, thus eliminating the noise. Since various processes such as the above can be performed, highly reliable magnetic card read data can be obtained.

In the above embodiment, the case of reading the magnetic data of the ID card has been described, but the present invention is not limited to the ID card and can be applied to the reading of a magnetic recording medium such as a passbook. Further, the prescribed time for determination is not necessarily limited to the case of dividing into four equal parts, and may be divided into, for example, seven parts to be 5/7, 2/7, or the like.

[Effects of the Invention] As described above, according to the present invention, even if the conveyance speed of the magnetic recording medium changes, it is not affected by the change and stable reading data with high reliability can be obtained. A device can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 show an embodiment of the present invention.
FIG. 1 is a magnetic card reader device showing the configuration of a magnetic card reader, FIG. 2 is a block diagram showing the configuration of a reading circuit, FIG. 3 is a diagram showing the read waveform and inversion time, and FIG. 4 is a RAM storing the inversion time. 5 is a data storage diagram of FIG. 5, and FIG. 5 is an explanatory diagram of the FM recording method. 1 ... Transport path, 3 ... Read magnetic head, 9 ... A / D converter, 10 ... Magnetization reversal measurement unit, 11 ... Clock generator, 12 ... Storage unit, 13 ... Information processing unit, K …… ID card.

Claims (3)

[Claims] 1. A reproducing head for converting information of a conveyed magnetic recording medium into an electric signal, a means for detecting magnetization reversal from the electric signal of the reproducing head, and a signal from the magnetization reversal detecting means. A magnetic recording medium reading device comprising: means for detecting a magnetization reversal interval; means for storing the magnetization reversal interval; and means for discriminating data based on the stored magnetization reversal interval. 2. The magnetic recording medium reading device according to claim 1, wherein the data of the recording medium is determined after scanning the entire recording surface. 3. The magnetic recording medium reading device according to claim 1, wherein the determination of the data of the recording medium is made by following the change of the magnetization reversal interval and changing the determination reference.