JPH0636482Y2 - Magnetic recording / reproducing device - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal reproducing apparatus for a magnetic recording medium recorded by a frequency modulation method, and in particular, it reproduces an information signal without being affected by the relative speed of the magnetic head and the magnetic recording medium and records information. The present invention relates to a magnetic recording / reproducing device that separates the magnetic field.

[0002]

2. Description of the Related Art Conventionally, a drive system of a magnetic recording medium in a recording / reproducing apparatus for a magnetic recording medium such as a magnetic card is as follows.
A driving method using a motor has been the mainstream because constant speed is required, but a manual drive type recording / reproducing apparatus has become widespread along with a demand for cost reduction of the apparatus. As a matter of course, as compared with the magnetic recording / reproducing apparatus driven by a motor, in the manual magnetic recording / reproducing apparatus, "unevenness" in the relative speed between the magnetic recording medium and the magnetic head becomes an important problem. Therefore, in such a manual device, the relative velocity between the magnetic recording medium and the magnetic head is detected when recording on the magnetic recording medium, and the velocity and JIS, ISO, AB are detected.
Information is recorded by synchronizing with a writing frequency suitable for the bit density defined by the standards such as A.

Therefore, the recording method on the magnetic recording medium is mainly the frequency modulation method (F2F method), and most of the recording density is 75 BPI or 210 BPI. At present, the most popular credit card with a magnetic stripe has a JIS standard with a binary code recording density of 210 BPI of 8.268 bits / mm, that is, 0.121 ± 0.012 mm / bit (allowable error ± 10
%).

A conventional method of reading the recorded magnetic recording medium by a reproducing apparatus will be described with reference to FIGS. When the magnetic recording medium 100 is brought into contact with the magnetic head 101 to run as shown in FIG. 4, the magnetic recording medium 20 is moved as shown in FIG.
The bit interval B ₁ recorded at 0 passes at a certain speed. During this time, time t ₁ elapses as shown in the output waveform 201. Leave this time t ₁ measured by the method described later stored by predicting the next bit passing time t ₂ monitors whether between the output of the constant ratio of the time t ₂ 'for the t _2, the output is If there is no output, it is judged as "0", and if there is an output, "1"
To determine.

In FIG. 4, reference numeral 102 is a shaping circuit for the output waveform 201.
Judge "0". 104 is an output terminal for the above data, 1
Reference numeral 05 is an output terminal for a read sync pulse of output data. The relative speed between the magnetic recording medium and the magnetic head is counted by the counting circuit by the reference clock generated inside the logic circuit 103, and the prediction judgment time is calculated by a predetermined calculation and stored in the storage circuit. Accumulated.

[0006]

[Problems to be solved by the invention] Now, in this method,
The read characteristics are affected by the performance of the logic circuit. That is, the frequency fluctuation of the reference clock, the maximum number of counting circuits,
It is affected by the tolerance of prediction judgment time. Further, since this logic circuit is composed of many logic gates, it must be manufactured in a large scale integrated circuit in order to achieve miniaturization, and it becomes expensive in a small quantity production.

The present invention has been made in view of such drawbacks, and an object thereof is to provide an inexpensive magnetic recording / reproducing apparatus in which the expensive and complicated logic circuit as described above is omitted. Another object of the present invention is to provide a magnetic recording / reproducing apparatus capable of reliable reproduction without being affected by the relative speed of the magnetic recording medium and the magnetic head.

[0008]

In a magnetic recording / reproducing apparatus according to the present invention, a plurality of head gaps with respect to a magnetic head are provided at intervals proportional to a magnetic flux reversal length recorded on a magnetic recording medium and in a recording / reproducing direction. On the other hand, a circuit for shaping the waveforms of a plurality of reproduction signals obtained by the magnetic head from the magnetic recording medium recorded by the frequency modulation method, and a plurality of outputs from the waveform shaping circuit are exclusive. A first logic circuit that obtains a synthesized waveform signal by synthesizing by a logical sum, a delay circuit that receives one of a plurality of outputs from the waveform shaping circuit as an input, one of the plurality of outputs, and an output of the delay circuit And a circuit for extracting a read sync pulse with respect to the composite waveform of the first logic circuit in combination with a second logic circuit that receives as an input, and described by the composite waveform signal and the read sync pulse. Characterized by being adapted to reproduce the information.

[0009]

【Example】

An embodiment of the present invention will be described below. FIG. 1 is a block diagram schematically showing the configuration of an embodiment of the present invention. Further, FIG. 2 shows the output from the magnetic head in the apparatus over time, and FIG. 3 shows a logical time chart for reading recorded information from a reproduction signal. In FIG. 1, in the present embodiment, two head gaps 302 and 303 are provided in the magnetic recording medium 3 in the magnetic head.
The magnetic head main body is not shown in the figure for the sake of convenience. In other words, the head gaps 303 are arranged at least half the bit density length with respect to the head gap 302, that is, at intervals of 1/2 of the length B in FIG.

Such head gaps 302 and 303
When the magnetic recording medium 301 moves in the direction of the arrow while contacting both of them, the output waveform from the head gap 302 becomes as shown by 402 in FIG. 2, and the output waveform from the head gap 303 becomes as shown by 403 in FIG. Become. At this time, the time t in FIG. 2 depends on the moving speed of the magnetic recording medium 301.

Referring also to FIG. 3, the reproduced signal when recorded on the magnetic recording medium 501 is shaped by the output waveform shaping circuit 304 into a reproduced signal from the head gap 302 as indicated by 502. The reproduced signal from the head gap 303 is shaped like 503. These output waveforms are input to the first logic circuit 305 of FIG. 1 and synthesized, and are output from the data output terminal 308 to 50 of FIG.
An output waveform such as 4 is obtained. The structure of the first logic circuit 305 for obtaining such an output waveform may be an exclusive OR circuit, and may be composed of an inexpensive standard logic circuit that is commercially available.

A delay circuit 306 that uses the rising and falling timings of the output waveform 503 as a read sync pulse for the output waveform 504 and receives the output waveform 503 as an input.
A combination of the output waveform 503 and the second logic circuit 307 which receives the output waveform 503 and the output of the delay circuit 306 as an input provides the output waveform 505 in which the generation of the waveform in the broken line portion is suppressed. In other words, the waveform shown by the broken line of the output waveform 505 is obtained by stopping the clock after detection of the recording information "1" in the second logic circuit 307 to obtain a read sync pulse having a constant period as shown in the figure.

Data output 50 according to this synchronizing pulse
By detecting the level of 4, the pattern of the data recorded on the magnetic recording medium as shown by 506 in FIG. 3 can be obtained. Since the read sync pulse in the present invention is generated from the reproduction signal obtained at the head gap, it is suitable for the combined signal which responds to the change in the relative speed of the magnetic recording medium and the magnetic head and changes in accordance with the change in the relative speed. The level can be detected at the timing. Therefore, it is not necessary to generate the reference clock as described in the conventional example, and it is not necessary to consider the variation factor.

The present invention is not limited to the embodiment, and for example, the head gap arranged in the magnetic head is
There is no particular limitation as long as it is an interval equal to or greater than the magnetic flux reversal length recorded on the magnetic recording medium, and the number of head gaps is arbitrary. The effect of increasing the head gap is more effective in terms of confidentiality than the case of using two head gaps. Further, it goes without saying that the logic circuit configuration for finally obtaining the pattern as shown by 506 in FIG. 3 from the reproduced signals from the respective head gaps can be realized in various ways depending on the number of reproduced signals and the combination thereof.

[0015]

As described above, according to the present invention, in the magnetic recording / reproducing apparatus for the magnetic recording medium recorded by the frequency modulation method, the gap of the magnetic head is aligned with the magnetic flux reversal direction recorded in the magnetic recording medium. By arranging at a spacing proportional to the bit density length and performing processing such as synthesis of the signals output from the respective gaps in the first logic circuit, the relative speed between the magnetic recording medium and the magnetic head is not affected. It becomes possible to play recorded information on
Moreover, it is possible to provide a magnetic recording / reproducing apparatus that is inexpensive and highly reliable in reading because it does not require a complicated circuit.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a magnetic recording medium and a reproduction signal according to the method of the present invention.

FIG. 3 is a time chart diagram for explaining the operation of the configuration of FIG.

FIG. 4 is a block diagram schematically showing an example of a conventional magnetic recording / reproducing system.

FIG. 5 is a diagram showing a relationship between a magnetic recording medium and a reproduction signal according to a conventional method.

[Explanation of symbols]

 301, 401 magnetic recording medium 302, 303 magnetic head gap 304 waveform shaping circuit 305 first logic circuit 307 second logic circuit 306 delay circuit

Claims (1)

[Scope of utility model registration request] 1. A plurality of head gaps for a magnetic head are arranged at intervals proportional to the magnetic flux reversal length recorded in a magnetic recording medium and in the recording / reproducing direction, while recording by a frequency modulation method. A circuit for shaping the waveforms of a plurality of reproduced signals obtained from the magnetic recording medium by the magnetic head and a plurality of outputs from the waveform shaping circuit by exclusive OR to obtain a synthesized waveform signal; Logic circuit of
The combination of the delay circuit that receives one of the plurality of outputs from the waveform shaping circuit and the second logic circuit that receives one of the plurality of outputs and the output of the delay circuit as the input A magnetic recording / reproducing apparatus comprising: a circuit for extracting a read sync pulse with respect to a composite waveform of a logic circuit, and reproducing recorded information by the composite waveform signal and the read sync pulse.