JPS607654A - Magnetic recording and demodulating system - Google Patents

Abstract

PURPOSE:To obtain correct writing density easily by detecting the writing density from a timing signal from a slit encoder. CONSTITUTION:A signal detected by an optical sensor 5 in the slit encoder 5 is applied to an interval counter 11 through the (b) side of a mode alteration switch 10 to measure the period of the signal. The measured result is stored in a writing density area of a read data memory 12. Then, the switch 10 is turned to the (a) side, data read out by a reading head 1 are applied to a counter 11, the counter 11 measures the interval and the memory 12 stores the measured result. The interval of the read data and the period of the writing density are sent to a demodulating circuit 3, which demodulates the read data while referring to the writing density. Thus, the correct writing density can be easily obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention is directed to a magnetic recording method using the FMHC recording method that allows the correct writing density for demodulating data written on a magnetic recording medium to be easily obtained. This article is about demodulation methods.

(2) Prior Art and Problems Conventionally, an FM recording method, such as the F2F method, is used to record information on a magnetic strip provided in a bankbook, card, or the like. That is, 1” corresponds to the timing period of the slit encoder implemented for magnetic stripe writing.
For the pulse width (frequency) of , “0” is twice the pulse width (
1/2 frequency).

In reproduction in this case, if it is less than 75% of the timing period, it is determined to be 1", if it is from 75% to 150%, it is determined to be "0", and if it is more than 150%, it is determined that there is a missing bit.

In order to reproduce magnetic data written using the 11i'M recording method, the reference cycle is required.

As shown in Figure 1, from readhead 1 to preamplifier 2.
When the demodulation circuit 6 outputs read data with a 1", "o' purple effect through the demodulation circuit 6, the writing density setting unit 4 has conventionally provided a terminal or a monolithic device that provides a predetermined cycle from the outside to the demodulation circuit 3. Set reference signals such as tables. There is also a method of detecting the insertion density using the detection signal of the read head.
As an alternative, a configuration for writing predetermined bits such as all "0" is required, which has the drawback of complicating the data writing procedure.

(3) Object of the Invention The object of the present invention is to provide an FM magnetic recording demodulation method that can easily obtain the correct writing density for demodulating magnetic stripe data written using the FM recording method.

(4) Structure of the Invention In order to achieve the above object, the FM@air recording demodulation system of the present invention has a magnetic head and an encoder that provides timing for recording onto a magnetic recording medium, In a magnetic recording demodulation method for reproducing recorded data, a detection means is provided for switching and detecting read data of the magnetic recording medium and a write timing signal from the encoder, and demodulates the read data with reference to the write timing signal. It is characterized by this.

(5) Embodiments of the invention The reference signal for the writing density used in the present invention is set internally rather than externally, and the writing density is obtained from a timing signal from a slit encoder rather than from data as in the past. The writing density is detected by switching when reproducing magnetic stripe data, is stored in the memory together with the read data, and is used for demodulation.

FIG. 2 is an explanatory diagram of the configuration of an embodiment of the present invention.

In the figure, an example of a magnetic stripe recording/reproducing apparatus using the FM recording method is shown. Magnetic card 2 shown in Figure 6
Read for magnetic stripe 21 of 0.

The write head is moved relatively to perform recording and reproduction using the F2F method. That is, a slit encoder 5 is provided directly connected to the moving mechanism of these heads, and a magnetic stripe 21 is provided along the optical sensor length 6 composed of a light emitting element and a light receiving element.
and head relative movement control and write timing.

That is, the write data is input to the data write circuit 8 via the preamplifier 7 to control the write data, and is sent to the write head 9 and written on the magnetic stripe 21.

When the magnetic stripe 21 written in this way is read by the read head 2 at another time, in the present invention, the optical sensor 6 of the slit encoder 5 The period of the signal is measured by the interval counter 11 through the preamplifier 7, b II of the mode selector switch 10, and is stored in the write density area in the read data memory 12. Next, when entering the part of the magnetic stripe where data exists, the mode changeover switch 10 is switched to the α side, the data read from the read head 1 via the preamplifier 2 is input to the interval counter 11, and the start-up system of the 12F method is inputted to the interval counter 11. The intervals between falling edges are measured and stored and held in the read data memory 12 sequentially. Each interval of these read data and the cycle of the write density are sent to the demodulation circuit 6, and if it meets the above-mentioned criteria, that is, 75% or less of the cycle of the write density, it is 1''.
, 75% to 150%, it is determined to be 0'', and if it is 150% or more, it is determined that a bit is missing, and the result is sent as a demodulated output.In addition, in this configuration, the write timing control of the write data of the data write circuit 8 is performed. The period of the packing density in the serial data memory 12 may be used as necessary.

FIGS. 4(α) to 4(d) are operational waveform diagrams of essential parts of the embodiment of FIG. 2.

(α) in the same figure shows the switching operation of the mode changeover switch 10, in which the writing density is read in the b-law switching section in the head movement range of (b) in the same figure, and the optical sensor 6 shown in (c) in the same figure
The period of the slit signal from is the read data memo! 712
Then, the valley intervals of the read signal are stored in the read data memory 12 by the read head shown in FIG. As mentioned above, the demodulation is performed with reference to the .

As described above, according to the present invention, the magnetic stripe read data and the ξ write density from the encoder are switched and detected and held in the memory, and the read data is demodulated with reference to the write density. This simplifies the configuration procedure for adding data for writing density detection to the beginning of data as in the past, and has the advantage of being able to deal with changes in writing density without making any adjustments. be.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the conventional example, Fig. 2 is an explanatory diagram of the configuration of the embodiment of the present invention, Fig. 6 is an explanatory diagram of the magnetic stripe, and Fig. 4 is an operational waveform of the main part of the embodiment of Fig. 2. In the figure, 1 is a read head, 2.7 is a preamplifier, 6 is a demodulation circuit, and 5
1 is a slit encoder, 6 is an optical sensor, 8 is a data write circuit, 9 is a write head, 10 is a mode changeover switch, 11 is an interval counter, 12 is a read data memory, 20 is a card, and 21 is a magnetic stripe. Patent applicant Fujitsu Ltd. sub-agent Patent attorney 1) Yoshishige Saka Figure 1 Written data Figure 4 I) side

Claims (1)

[Claims] In the magnetic recording demodulation method, which uses a magnetic head and an encoder that provides timing for writing to a magnetic recording medium, and reproduces data written on the magnetic recording medium, the read data and the read data of the magnetic recording medium are reproduced. A configuration means is provided for switching and detecting a write timing signal from the encoder,
A magnetic recording demodulation method characterized in that read data is demodulated with reference to the write timing signal.