JPH0896313A - Magnetic data reader - Google Patents

Abstract

PURPOSE: To enable a magnetic data reader to read out data even when noise exists by equipping a readout means for reading out data recorded on a magnetic recording medium making a comparison between a detected signal and a generated 2nd-order envelope. CONSTITUTION: When a magnetic card C is inserted into a magnetic card processor, and a magnetic head H is slid, an analog signal of an output waveform corresponding to data recorded on the card C as shown by (1) in the figure is obtained, and this signal is converted into a digital signal by an A/D converting circuit 10 and stored in a memory of a CPU 11. Then, upper and lower peak values are extracted out of the data, and a 1st-order envelope is generated by connecting up these peak values as shown by (2) in the figure. Then, the 2nd-order envelope (3) is generated by multiplying the (2) by a fixed value, e.g. 0.8. This (3) has a characteristic feature of varying to follow a variation in its output level even when the variation is largely made by noise, etc., and always exactly grasping a flux change. Consequently, the reliability of the magnetic card processor when the card C is set in the processor can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic data reader for reading data recorded on a magnetic recording medium such as a magnetic card, and more particularly, it is called a frequency modulation (FM) system or an F2F system. Reading device.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing a schematic configuration of a conventional F2F type magnetic data reader, in which a magnetic recording medium (hereinafter referred to as a magnetic card) C is pinched via a transport mechanism (not shown). When the roller R moves while contacting the magnetic head H while being pressed by a predetermined pressure, the magnetic head H is configured to obtain a waveform output of a read voltage corresponding to the data recorded on the magnetic card C. .

An output from the magnetic head H is processed by a peak detection / amplification circuit 1 having an amplification function, a peak detection function and a waveform shaping function, and then input to an F2F demodulation logic circuit 2. The peak detection / amplification circuit 1 and the F2F demodulation logic circuit 2 are usually composed of a semiconductor integrated circuit (LSI).

As shown in FIG. 5, the F2F demodulation circuit 2 is configured to generate an F2F signal synchronized with a clock signal. That is, this F2F signal is
When there is no edge change within 1 bit, that is, when one peak is detected and frequency is 1F, logical value "0"
Also, when there is an edge change in one bit, that is, when two peaks are detected and the frequency is 2F, the logical value is "1".

The signal (data) converted into the F2F pattern signal by the F2F demodulation circuit 2 has a predetermined number of bits read and discarded in order to remove the unstable data at the beginning of the data reading of the magnetic card C. , The serial interface (I / F) circuit 3 is incorporated into the CPU 4.

For example, when the magnetic data reader is incorporated in an automatic ticket gate, the CPU 4 controls the automatic ticket gate in a centralized manner. Therefore, the data taken in via the serial I / F circuit 3 is used for the arithmetic processing of the ticket gate processing.

[0007]

However, in the above-described conventional magnetic data reader, the peak detection is performed with reference to a predetermined threshold in the processing until the signal read by the magnetic head is input to the CPU. Therefore, since the peak is detected based on the threshold value that is set to a value slightly smaller than the peak value when the signal read by the magnetic head is normally read, the magnetic card is damaged. Due to noise such as noise, all read signals that deviate from a predetermined threshold result in a read error, and there is a drawback that the reliability of the entire system incorporating the magnetic data reader, for example, an automatic ticket gate, is reduced.

Therefore, the present invention has been made to solve the above-mentioned drawbacks, and an object of the present invention is to provide a magnetic data reading apparatus capable of reducing reading errors and improving reliability. .

[0009]

In order to achieve the above object, a magnetic data reader according to the present invention extracts a peak value from a signal obtained by detecting data recorded on a magnetic card through a magnetic head. A peak value extracting means, a primary envelope generating means for connecting the extracted peak values to generate a primary envelope, and a secondary envelope by connecting a value of a predetermined lower ratio than the generated envelope. A secondary envelope generating means for generating a line; and a reading means for comparing the detected signal with the generated secondary envelope and reading data recorded on the magnetic recording medium. I am trying.

[0010]

In the above construction, the reading means is based on the secondary envelope which is lower than the primary envelope generated by connecting the peak values of the signals detected by the magnetic head by a predetermined ratio, that is, the second envelope.
The data of the magnetic card is read using the next envelope as a threshold.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of an apparatus according to an embodiment. It should be noted that the same components as those of the related art will be described using the same reference numerals.

When the magnetic card C moves in contact with the magnetic head H while being pressed by the pinch roller R with a predetermined pressure via a transport mechanism (not shown), the data recorded on the magnetic card C is changed from the magnetic head H. The output waveform of the corresponding read voltage is obtained. The solid line in FIG. 2 represents an example of the output wave.

An analog signal from the magnetic head H is input to a known A / D converter 10, converted into a digital signal, and taken into the CPU 11. For example, when the magnetic data reader is incorporated in an automatic ticket gate, the CPU 11 centrally controls the automatic ticket gate. Therefore,
The data read by the magnetic head H is finally used for the calculation process of the ticket gate process.

Next, the data reading control operation of the magnetic card C will be described with reference to the waveform diagram of FIG. 2 and the flowchart of FIG.

Now, when the magnetic card C is inserted into a magnetic card processing machine such as an automatic ticket gate and slid on the magnetic head H (Yes in step 100; hereinafter, step is referred to as S), the magnetic head H is detected. From, an analog signal having an output waveform corresponding to the data recorded on the magnetic card C as shown in FIG. 2 is obtained.

The analog signal is converted into a digital signal by the A / D conversion circuit 10 and stored in a memory (not shown) of the CPU 11 (S102). Then, upper and lower peak values are extracted from the stored data, and the peak values are further connected to generate a primary envelope curve shown in, of FIG. 2 (S106).

Then, the generated primary envelope is multiplied by a constant value, for example 0.8, to obtain the secondary envelope (see FIG. 2).
(Reference) is generated (S108). This secondary envelope,
Is a threshold value when F2F data is created. That is, based on the time when the data detected by the magnetic head H shown in FIG. 2 changes beyond the secondary envelope curve to the secondary envelope curve again, that is, whether or not the flux has been changed. As a result, F2F data is created (S110).

As shown in FIG. 2, the quadratic envelope generated as described above fluctuates in accordance with the fluctuation of the output level due to noise or the like, and the flux is always It has the feature of being able to accurately grasp changes. Therefore, the F2F data is generated regardless of noise.

Therefore, when the apparatus of this embodiment is incorporated in a magnetic card processor such as an automatic ticket gate, the reliability of the magnetic card processor can be improved.

Note that, in FIG. 2, the symbols and indicate the threshold values when the conventional flux change is performed. This threshold value is a value slightly lower than the peak value (values on the left and right in the example of FIG. 2) when the magnetic head H normally reads from the magnetic card C, that is, when there is no obstacle such as noise. Is set to. Therefore, in the case of read data due to noise or the like located in the middle of FIG.
It means that the flux cannot be changed, the peak cannot be detected, and the F2F data creation becomes difficult.

In the above embodiment, the secondary envelope is 1
The next envelope was 0.8 times, but according to the experiment,
If it is 0.6 times, the F2F data can be created accurately.

[0022]

The magnetic data reader according to the present invention comprises a peak value extracting means for extracting a peak value from a signal obtained by detecting data recorded on a magnetic card through a magnetic head, and the extracted peak value. To generate a primary envelope curve, and a secondary envelope curve is generated by connecting a primary envelope curve generating means for generating a primary curve curve and a value of a predetermined lower ratio than the generated envelope curve.
Since the secondary envelope generating means and the reading means for reading the data recorded on the magnetic recording medium by comparing the detected signal with the secondary envelope generated, the magnetic card may be damaged. It has a feature that it can be read even if there is noise.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is an output waveform of a magnetic head.

FIG. 3 is a flowchart illustrating a control operation.

FIG. 4 is a schematic configuration diagram of a conventional device.

FIG. 5 is an explanatory diagram of F2F data.

[Explanation of symbols]

 10 A / D converter 11 CPU R Pinch roller H Magnetic head C Magnetic recording medium (magnetic card)

Claims (1)

[Claims] 1. A peak value extracting means for extracting a peak value from a signal obtained by detecting data recorded on a magnetic recording medium through a magnetic head, and a primary envelope curve generated by connecting the extracted peak values. Do 1
A secondary envelope generating means, a secondary envelope generating means for generating a secondary envelope by connecting a value of a predetermined lower ratio than the generated envelope, the detected signal and the generated secondary A magnetic data reader comprising: a reading unit that compares the envelope with the data recorded on the magnetic recording medium.