JPS58147813A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To reduce both of a peak shift due to a demagnetizing field generated by a previous bit on a recording medium during recording and a peak shift due to the asymmetry of intervals of magnetism inversion. CONSTITUTION:A signal inputted to an input terminal 71 is supplied to the plus input terminal 77 of an adder 74 through a delay circuit 72 and also supplied to the input terminal of the 2nd delay circuit 73. The output signal of the delay circuit 73 is supplied to the 1st minus input terminal 78 of the adder 74. Further, the signal inputted to the input terminal 71 is supplied to the 2nd minus terminal 79 of the adder 74 through a voltage divider 75. The adder 74 performs arithmetic of (voltage at plus input terminal 77) - (voltage at 1st minus input terminal) - (voltage at 2nd minus input terminal) and sends out its output to an output terminal 80. The output reduces peak shifts due to waveform interference while reducing the influence of a demagnetizing field.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing device, and relates to a magnetic recording and reproducing device having a reproducing circuit in 1%.

As shown in FIG. 1, in a general recording and reproducing circuit of a magnetic recording and reproducing device, when write data is input to a write data input terminal 3, a predetermined code conversion is performed by a modulator 4, and a predetermined code conversion is performed by a write circuit 5. A write current having a waveform 21 shown in FIG. 2 is supplied to the coil 6 of the magnetic head l, and write data is recorded on the magnetic recording medium 2 as magnetization information.

During reproduction, magnetization information of the recording medium 2 is detected by the magnetic head 1, a signal voltage is generated in the coil 6, and the read voltage 22\r is amplified by the read amplifier 7 as shown in the waveform 22 in FIG. A peak detector 8 detects a peak pulse 23 corresponding to the peak timing of the successive waveform. On this occasion,
The timing of the detected peak pulse 23 is detected with a time difference of 24.25 with respect to the recorded timing. This is due to interference between magnetization information recorded before and after. The peak pulse 23 is supplied to a synchronous oscillator 9 and a demodulator 10, and the synchronous oscillator 9 generates a clock signal synchronized with the average clock frequency of the peak pulse, and uses the clock to generate a data discrimination quid pulse 26. , a demodulator 10 performs full logic discrimination on the readout signal depending on whether there is a peak pulse within the discrimination window, and outputs it to the output terminal 11 as a readout data pulse.

During this series of demodulation operations, the detected peak pulse may be detected with a relative shift with respect to the recording timing due to interference of recorded magnetization information. This is generally called a peak shift, and if this peak shift becomes large, the signal may jump out of a predetermined discrimination window or may be mixed in excessively, causing data errors. FIG. 3 shows an example of a recording current and an example of a corresponding peak shift. In general, a peak shift occurs when the magnetization reversal interval is around 1 and is asymmetric, because the interference of the magnetization information becomes asymmetric.
Even if the magnetization reversal intervals before and after the central magnetization reversal portions are symmetrical, the peak shifts will have different values such as 37.38. This is because during recording, the demagnetizing field generated from the previous magnetization pattern that has already been recorded is superimposed on the recording, and all data is recorded 7 feet before the desired recording timing. This 77g becomes larger as the demagnetizing field becomes larger, so the area 33 where the magnetization reversal interval is small
is larger than the section 32 where the magnetization reversal interval is large. The peak shifts 39 and 40 are caused by the superposition of the effect due to the demagnetizing field and the effect due to the asymmetry of the magnetization reversal interval described above.

FIG. 4 shows a peak shift compensation circuit, which is part of a conventional regeneration circuit that reduces the peak by 7 feet. This peak shift compensation circuit is generally inserted between readout amplifier 7 and peak detector 8 in FIG. This peak shift compensation circuit will be explained using an isolated magnetization reversal waveform as an example.@The signal voltage induced in the magnetic head coil 6 is as follows.
The signal is amplified by the read amplifier 7 and input to the input terminal 41 in FIG. The input waveform is delayed by a delay circuit 42 and then sent to an adder 43.
The voltage is supplied to the plus input terminal 46 of the adder 43, divided by the voltage divider 44, and supplied to the minus input terminal 47 of the adder 43. On the other hand, since the output terminal of the delay circuit 42 is open, the input signal is totally reflected and appears at the input terminal 41. This input terminal 4
The waveform appearing at 1 is voltage-divided by the voltage divider 44+, and is similarly supplied to the negative input terminal j7 of the adder 43. The operating waveforms of this circuit are shown in FIG. That is, waveform 51
．． Reference numeral 53 is an i-type waveform obtained by dividing the waveform appearing at the input terminal 41 by the voltage divider 44, and the polarity is reversed for convenience since it is input to the minus input terminal of the adder circuit.

A waveform 53 is a reflected wave of the input wave i, and is delayed by twice the delay time T of the delay circuit 42. The waveform 52 is the output of the delay circuit 42 and is delayed by the delay time T from the input waveform. Output 4 of adder 43
5, a waveform 54 obtained by subtracting the waveform 51 and the waveform 53f from the waveform 52 is output. The waveform 54 has a smaller pulse width than the one-element waveform 52, and the amount of interference with the previous and subsequent waveforms becomes smaller, resulting in a smaller peak shift. however,
Although the waveform in FIG. 5 is assumed to be symmetrical with respect to the temporal central axis 55, in reality, as described above, even if the isolated magnetization reversal waveform is nearly symmetrical, when recording, Since the demagnetizing field generated from the magnetized part of the magnet is recorded in a superimposed manner,
When the isolated magnetization reversal waveform that causes a peak shift such as 36 in FIG. 3 is calculated, the leading edge becomes wider than the trailing edge as shown in waveform 62 in FIG. It becomes an asymmetrical trap. Therefore, in this type of conventional circuit, no improvement in peak shift due to the influence of a demagnetizing field during recording can be expected.

The present invention is capable of recording the previous pixel on the recording medium that has already been recorded during recording.
The present invention provides a reproducing circuit that is effective in reducing both the peak shift caused by the demagnetizing field generated by K and the peak shift caused by the asymmetry of the VB magnetization reversal interval, and further improves the reliability of continuous data. The present invention provides a magnetic recording and reproducing device with improved performance.

According to the present invention, in the reproducing circuit of a magnetic recording and reproducing device,
A first signal obtained by inputting a reproduction signal from a magnetic head and delaying the input signal in a first delay circuit, a second signal obtained by attenuating the input signal from the first signal amplitude, and a first signal. The signal is further delayed by a second delay circuit and a third signal whose amplitude is attenuated compared to the first signal is generated from the signal @1.

A first means comprising a subtraction circuit configured to subtract the second signal and the third signal, and making the delay time of the first delay circuit larger than the delay time of the second delay circuit, or A magnetic recording and reproducing circuit using a second means for making the third signal amplitude smaller than the second signal amplitude, or a combination of the first means and the second means, completely blinding the magnetic recording and reproducing circuit. A recording and reproducing device is obtained.

Since the demagnetizing field of the direct-spun magnetization pattern that has already been recorded is superimposed on the recording magnetic field, the recorded magnetization pattern is distorted. This distortion is caused by the fact that when the recorded magnetization pattern sequence is separated into individual isolated magnetization reversal reproduction signals as a superposition of isolated magnetization reversal reproduction signals, the rise time of the leading edge of the isolated magnetization reversal reproduction signal is exactly 1 Since the waveform is widened, when modifying the waveform during reproduction, the amount of modification for the # edge is made larger than the amount of modification for the trailing edge to compensate for the influence of the demagnetizing field q#.

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 7 shows a circuit for compensating for peak shift used in one embodiment of the present invention. This circuit is inserted between the readout amplifier 7 and the peak detector 8 of a general magnetic recording/reproducing circuit. The general structure of the magnetic recording/reproducing circuit is the same as the conventional circuit shown in FIG. 1, so a description thereof will be omitted.

In FIG. 7, an input terminal 71 receives a signal from a continuous amplifier 7 which amplifies the reproduction output voltage of the magnetic head. The signal input to the input terminal 71 is supplied to the plus input terminal 77 of the adder 74 via the delay circuit 72, and the second
is supplied to the delay circuit 730 input terminal of. Delay circuit 73
The output signal of is applied to a first negative input terminal 78 of adder 74 via voltage divider 76 . Further, the signal input to the input terminal 71 is supplied to the second negative terminal 79 of the adder 74 via the voltage divider 75. Adder 74 #i calculates (voltage at positive input terminal 77) - (voltage at first negative input terminal) - (voltage at second negative input terminal), and sends the output to output terminal 80. FIG. 8 shows waveforms of various parts for explaining the operation of FIG. 7, and the characteristic operation described below will be explained.

As mentioned above, even though the isolated magnetization reversal reproduction waveform has a nearly symmetrical waveform, the center 4IK that descends from the peak of the waveform is the peak when the demagnetizing field of the previous bit that has already been recorded is recorded at the time of recording. The shift tends to be as shown in Figure 3.
When the input signal waveform is separated by calculation into an isolated magnetization reversal waveform that causes such a peak shift, a waveform with a trailing edge wider than a leading edge, as shown in waveform 82 in FIG. 8, is obtained. Therefore, by making the amount of compensation for the leading edge of the isolated magnetization reversal waveform larger than the amount of compensation for the trailing edge, it is possible to reduce the influence of the demagnetizing field and to perform compensation that reduces the amount of waveform interference. A waveform 81 in FIG. 8 is a waveform obtained by dividing the waveform input to the input terminal 71 by the voltage divider 75.

To input to the minus input terminal of addition @74.

- For convenience, the polarity is reversed. This waveform is obtained by delaying the 82 input waveforms by the delay circuit 72 by a time T1.

The waveform 83 is the waveform 82t--and is further processed by the delay circuit 73 for time T2.
The waveform is delayed by 1 and divided by the voltage divider 76, and the adder 74
For convenience, the polarity is shown reversed because the V-input terminal is used for input. The waveform at the output terminal 80 of the adder 74 is obtained by combining the respective input waveforms 81, 82, and 83, and a waveform 84 is obtained. When the waveform is affected by the demagnetizing field, it becomes a waveform whose leading edge is equivalently widened, so the waveform 8 that compensates for the leading edge is created.
1 is made larger than the amplitude E2 of the waveform 83 that compensates for the trailing edge.

In addition, by making the time TI from waveform 81 to waveform 82 larger than the time T2 from waveform 82 to waveform 83, the amount of compensation for the leading edge of waveform 82 can be made larger than the amount of compensation for the trailing edge. can get. These waveforms 82
．． Since 84 is a waveform obtained by computationally separating the actual recording/reproducing waveform, the original waveform can be restored by computationally synthesizing the waveform. Therefore, if the reproduced waveform of the magnetization information recorded under the influence of the demagnetizing field of the previous bit during recording is input to the circuit shown in FIG. Shifts can be reduced.

The purpose of the above operation is to increase the amount of compensation for the leading edge of the isolated magnetization reversal waveform compared to the amount of compensation for the trailing edge.
>T2 and w, the conditions for >w2 are.

Even if only the condition T1>T2 or only the condition E, )E2 is adopted, the improvement to the best value cannot be achieved. Even if K is used, some improvement effect can be achieved.

As explained above, the present invention compensates for the peak shift of the reproduced waveform of magnetization information recorded due to the shadow I# of the demagnetizing field generated from the previous pit during recording, together with the peak shift due to interference during reproduction. Therefore, the operating margin of the magnetoresistive recording device can be increased.

[Brief explanation of drawings]

Figure 1 shows an example of a general magnetic recording/reproducing circuit. Figure #12 is a diagram for explaining the operation of Figure 1. Figure 3 shows the recording current waveform and the peak shift caused by it A diagram showing an example of the size, and FIG. 4 is a diagram showing a conventional circuit for compensating for peak shift. Figures 5 and 6 are diagrams for explaining the operation of Figure 4, Figure 7 is a diagram showing an embodiment of the present invention, and Figure 8 is a diagram for explaining the operation of Figure 7. FIG. 1...magnetic head, 2...recording medium,
3... Data input terminal, 4...
Modulator, 5...Writing circuit, 6...Magnetic head fill, 7...Reading amplifier, 8.
...Peak detector, 9...Synchronous oscillator. 10...OI adjustment device, 11...Enjoyment data output terminal. 21... Pledge current waveform, 22... Read voltage waveform, 23... Peak pulse, 26...
...Discrimination wind pulse, 27...Read data pulse, 31...Write current waveform, 3
6...Example of peak shift amount, 41...
・Input terminal, 42...Delay circuit, 43...
...Adder, 44...Voltage divider, 45...
・Additional: JII device output output terminal 1...Input terminal,
72...! 1 Sa circuit, 73... second delay circuit, 74... adder. 75...First voltage divider, 76...Second voltage divider
voltage divider. 80... Output terminal. Ei 1 drawing Koshirae 2 drawing

Claims (1)

[Claims] A first signal obtained by delaying an input signal in a first delay circuit;
a second signal obtained by attenuating the input signal from the first signal amplitude; and a third signal by further delaying the first signal by a second delay circuit and attenuating the first signal amplitude by p. In a magnetic recording/reproducing circuit comprising a subtraction circuit configured to generate a signal and subtract a second signal and a third signal from a first signal. A reproduction circuit characterized in that the delay time of the first delay circuit is larger than the delay time of the second delay circuit, and the third signal amplitude is smaller than the second signal amplitude. 1. A magnetic recording and reproducing device comprising: a reproducing circuit having at least one of a reproducing circuit and a reproducing circuit.