JP2000207704A - Signal processing device and digital signal recorder sharable between in-plane and perpendicular recording media - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a signal processing device dealing with both in-plane and perpendicular recording media by employing a signal processing means which can compensate for a record based on both lead and lag directions with respect to a normal bit position. SOLUTION: Recording is conducted using a both direction record compensation means which can lead or delay a recording signal with respect to a normal signal inverting position when it satisfies some conditions. A digital signal Din is inputted, along with a clock signal synchronized therewith, to a recording side signal processing semiconductor device IC-W. The semiconductor device IC-W comprises a record encoding means 1 suitable of in-plane or perpendicular recording, and a both direction record compensation means 2 which can lead or delay the signal inverting position of an output signal CC from a normal position. An output signal CR subjected to record compensation is recorded on a recording medium 4 through a record amplifying means 3. When such a both direction record compensation means 2 is employed, the signal processing device can be shared between in-plane and perpendicular recording media.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a signal processing device using a signal processing method capable of sharing digital data with an in-plane recording medium and a perpendicular recording medium, and an applied apparatus using the device.

[0002]

2. Description of the Related Art As the operation speed of a computer increases, application software requiring a large-capacity memory is used, and the demand for high-density small magnetic disks is increasing. For this reason, a so-called in-plane recording medium (hereinafter referred to as an in-plane recording medium) in which a magnetization pattern corresponding to a recording signal is formed in the direction of travel of a conventionally used recording head (circumferential direction of a disk). Along with the improvement in (1), use of a recording medium for perpendicular recording (hereinafter, referred to as a perpendicular recording medium) as a new high-density magnetic recording medium has been studied.

In a perpendicular recording medium, a magnetization pattern corresponding to a recording signal is formed in a direction perpendicular to the disk surface (thickness direction of the recording medium), magnetic repulsion between adjacent signals is small, and recording is performed stably at high density. There are features that you can do.

Currently, two types of perpendicular recording media have been proposed. One is a single-layer perpendicular recording medium in which a perpendicular recording film is independently formed on a disk surface. In this single-layer perpendicular recording medium, signals can be recorded by a conventional recording head, that is, a wound ring head. The other has a soft magnetic recording medium layer below the perpendicular recording medium.
The layer is a perpendicular recording medium. Since a magnetic layer is provided below the recording layer, the recording magnetic field works efficiently, and high recording efficiency (generation efficiency of a magnetic field effective for recording with respect to a recording current) can be obtained. In particular, when a recording head called a single pole head and a two-layer perpendicular recording medium are combined, high recording efficiency can be obtained.

[0005] In the future, there will be a shift to a perpendicular recording medium, but at present, the most suitable one is selected from an in-plane or perpendicular recording medium according to the device specifications. Therefore,
It has become necessary to provide a signal processing method and a signal processing device that can support these various recording media. This is a particularly important issue in signal processing in a measuring device for measuring the recording characteristics of a recording medium.

However, there is almost no mention of a signal processing method that can handle them in common because the two recording methods of in-plane recording and perpendicular recording have different reproduction waveforms. However, it has been proposed to standardize the reproduction signal processing by the following method. That is,
It is known that a reproduced signal of a single-layer perpendicular recording medium has a waveform obtained by differentiating a conventional in-plane recording reproducing signal, and is given in an integrated form in the case of a two-layer perpendicular recording medium. Therefore, the inverse integral or differential operation is performed to return the reproduced signal waveform to substantially the same as the conventional one, and the conventional reproduced signal processing is to be used.

The prior art of signal processing related to in-plane recording and perpendicular recording is disclosed in IEICE Transactions C.I.
I, J81-C-II, Vol. 4, No. 4, April 1998, pages 1-20.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a signal processing method which can cope with in-plane and perpendicular recording media. Specifically, based on the new fact that the appearance of the nonlinear bit shift is opposite in the in-plane recording and the perpendicular recording, by using signal processing means capable of compensating the recording in both the leading and delaying directions with respect to the normal bit position, , A signal processing device capable of handling in-plane and vertical recording media. Further, the present invention provides a reproduction signal processing means applicable to both recording media.

[0009]

According to the present invention, in recording a digital signal on a magnetic recording medium, if a recording signal satisfies a certain condition, a bidirectional recording compensating means can be advanced and delayed with respect to a normal signal inversion position. Record using.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a signal system diagram of a recording signal processing which can be commonly used for an in-plane and a vertical recording medium in one embodiment of the present invention. FIG. 2 is a corresponding signal system diagram on the reading side.

The digital signal Din to be recorded is input to the recording-side signal processing semiconductor device IC-W together with the clock signal C synchronized therewith. The IC-W includes a recording encoding means 1 suitable for in-plane or vertical recording, and a bidirectional recording compensating means capable of delaying or leading the signal inversion position of the output signal CC of the recording encoding means 1 from a normal position. Consists of two. The output signal CR that has been subjected to the recording compensation is recorded on the recording medium 4 by the recording head (not shown) via the recording amplifier 3.

In reading, a read signal obtained from the recording medium 4 via a read head (not shown) is:
The signal is amplified by the reproduction amplifier 5 to a predetermined signal amplitude. The output signal is corrected by the reproduction equalizing means 6 so as to compensate for the transfer characteristics received during the recording process and the reading process, and to have a predetermined waveform response for detecting the recording signal CC from the reading signal.

The equalized signal containing noise mixed in the recording process and the reading process is output by the detecting means 7 as a detection signal which is most probable for the original recording signal CC. The original digital signal Din * is obtained by the decoding means 8 which performs the reverse conversion of the recording signal on the output signal. Since a code error is included, it is distinguished by adding an asterisk (*).

Before describing in detail the bidirectional recording compensating means 2 which can be used for both in-plane and perpendicular recording, FIG.
The relation between the recording compensation and the nonlinear bit shift and the characteristics of the nonlinear bit shift in the in-plane and perpendicular recording will be described with reference to FIG.

(L-1) in FIG. 1 shows a part of the output signal of the recording encoding means 1. Tc indicates a bit interval, which corresponds to the shortest signal inversion interval. This (L-1)
When the signal is recorded on the in-plane recording medium without recording compensation, the read signal moves forward, that is, bit-shifts, at the inversion positions b1 and b2 where the signal is inverted immediately before, as shown in (L-2). . The other inversion positions do not move.
Since a bit shift occurs only under a certain condition, it is called a non-linear bit shift.

[0016] Reproduction equalization means 6 and detection means 7 on the read side
Cannot deal with such non-linear disturbances. For this reason, it is necessary to take measures to prevent non-linear interference from occurring on the recording side. This process is called recording compensation. More specifically, inversion positions b1 and b2 where a nonlinear bit shift is expected to occur are detected in advance from the recording signal sequence CC, and the inversion positions are shifted in the direction opposite to the nonlinear bit shift, that is, (L− The recording-compensated signal CR is formed and recorded as in 3). As a result, a read waveform close to (L-1) can be obtained on the read side. On the other hand, in a perpendicular recording medium, the amount of nonlinear bit shift is characterized by being smaller than that in longitudinal recording, but a detailed examination revealed that the direction of nonlinear bit shift appeared opposite to that in longitudinal recording. . That is, if the original signal sequence before the recording compensation is given by (P-1), if the recording is performed without the recording compensation, a read signal as shown by (P-2) is obtained.
The direction is opposite to that in the plane. For this reason, in the perpendicular recording, a recording signal given by (P-3) by the recording compensating means is required. FIG. 4 shows an embodiment of a detailed circuit diagram of the recording compensation means 2 which can be used for both in-plane recording and perpendicular recording. Also,
FIG. 5 shows the waveform of each part in FIG. The output signal of the recording encoding means 1 is a D-type flip-flop (D-FF) 2-1.
And becomes a CC signal. The recording code 1 is an NRZ signal represented by a high level and 0 is a NRZ signal represented by a low level. DF
The clock signal is delayed by one clock at F2-2, and a position where 1s continue is detected by the AND circuit 2-3, and the control signal SW is generated. On the other hand, in order to generate a recording signal in the NRZI format according to the recording codes 1 and 0, first, the D-FF 2-10 transmits the CC signal.
The signal is input to form a signal (L-1) which is inverted at a normal position. The signal (L-1) is a buffer circuit 2-11, 2-12, 2-13, 2-14, 2-1 having a slight delay time.
5 are input one after another. The switch circuit 2-16 selects one signal from the outputs of the respective buffer circuits according to the value (S-L) of the selection signal S, and a signal having a predetermined delay time compared to the signal (L-1). D (L-1) is output. Only when the SW signal is high, the (L-1) signal and the D (L-1) signal are exchanged to make the recording signal (L-3) compensated for recording.
Is obtained.

For this reason, in the longitudinal recording medium, the medium selection signal Msw is set to Msw = 1 (high level), and the medium selection signal Msw is set via the buffer 2-5, the AND circuit 2-8, and the OR circuit 2-9.
The W signal is output. The SW signal is further supplied to a delay circuit 2-
17 and becomes the switching signal SW-L.
By using the delayed SW-L signal, switching is not performed at the rising and falling portions of each signal. As a result, an (L-3) signal is formed as an output of the switch 2-18, and a recording signal CR in which recording is compensated for in-plane recording is obtained.

When a perpendicular recording medium is used, the control signal S
Use the inverted version of W. Therefore, the medium selection signal is set to Msw = 0 (low level), and one input terminal of the AND circuit 2-7 is fixed to the high level by the inversion circuit 2-6. As a result, the control signal SW becomes the inversion buffer 2-
4. The switch 2-18 is controlled by the signal SW-P passed through the AND circuit 2-7 and the OR circuit 2-9 and further passed through the delay circuit 2-17. Therefore, when the signal SW-P is high, the D (L-1) signal is selected, and when the signal SW-P is low, (D-L-1) is selected.
1) A signal is selected. As a result, the (P-3) signal for vertical recording described with reference to FIG. 3 is equivalently obtained. However,
The delay time of the D (L-1) signal is changed to a value SP suitable for perpendicular recording by changing the value of the selection signal S.

As described above, by using the two-way recording compensating means 2, it is possible to realize a recording circuit system which can be commonly used for in-plane and perpendicular media.

FIG. 6 shows another embodiment. However, the connection method is different from that of FIG. 5, and the recording compensation means basically has the same concept. The same functional elements as those in FIG. 5 are denoted by the same numbers. In FIG. 6, the reference signal output is stored in a buffer 2-11.
Of the buffer located at the center of 2 to 15 (L-1)
c. The switch 2-16 selects a buffer output that is delayed or preceding the buffer output (L-1) c in accordance with in-plane or vertical recording. The value that sets the selection is given as SL (in-plane) or SP (vertical).

On the read side, the same circuit format can be used for both in-plane and vertical recording by changing the filter coefficient of the transversal filter described below.

FIG. 7 shows a specific circuit configuration of the reproduction equalizing means 6. The analog filter 6-1 is inserted to remove unnecessary noise outside the signal band. In order to perform high-speed and high-precision signal processing operations, continuous analog signals are converted into analog / digital converters (hereinafter, A / D) 6.
-2 converts it into a discrete digital signal sequence.

As described above, the reproduction equalizing means 6 compensates for the transfer characteristics received in the recording process and the reading process, and adjusts the frequency so as to have a predetermined waveform response for detecting the recording signal CC from the read signal. And phase correction.

This realizing means is a transversal filter shown in FIG. Transversal filter is A
/ D latch circuits 6-3-1 to 6-3-n having a time delay corresponding to the / D clock, and n coefficient multiplying circuits 6-4-1 to 6-4-4-associated with each latch circuit. n, and an adder group 6-5 for obtaining the sum of the outputs of the respective coefficient multiplying circuits.
Consists of The predetermined values of the coefficients c0 to cn to be given to the respective coefficient multiplying circuits are changed depending on which of the in-plane recording and the perpendicular recording is selected. The appropriate number of coefficients is from n = 10 to 15, but it is necessary to set the number as the recording density increases and the number increases.

FIG. 8 shows a decision feedback type equalizing means including a reproducing equalizing means and a detecting means which can be used for another in-plane and vertical recording. The read signal is a pre-filter (hereinafter, FFF) 9
It is corrected by -1 so as to have a predetermined waveform response.
This FFF also has the configuration of the transversal filter as shown in FIG. The predetermined waveform response means that when an isolated pulse is recorded and read out, the bit response of the pulse is set to a predetermined value (for example, 1)
Each filter coefficient of the FFF 9-1 is set by the setting circuit 9-1-S such that there is no response in the leading part of the pulse and all interference components occur in the trailing part of the pulse. The decision feedback equalizer converts the above-mentioned interference response from a signal already detected into a feedback filter (hereinafter, referred to as FBF) 9.
-4, and the FFF 9 through the addition circuit 9-2.
The interference component from -1 is removed. The detection circuit 9-3 detects the original recording signal CC from the signal from which the interference has been removed. For both in-plane and vertical recording, the coefficients of the filters 9-1 and 9-4 are set in accordance with each recording method by setting circuits 9-1-S and 9-4-S.
What is necessary is just to set by S. The setting method is to determine the optimum value of each coefficient so that the error rate after detection is minimized.

The recording and reproducing means that can be used for both in-plane and perpendicular recording have been described above. Hereinafter, the method used in each means will be described.

First, in recording encoding, high-density and high-speed recording are required. Therefore, a method that can set a large magnetization reversal interval of a recording signal is desired. Accordingly, in the recording encoding according to the NRZI rule that the magnetization is inverted when the signal is 1 and the magnetization is not inverted when the signal is 0, the recording and encoding in which the minimum number d of 0 included between 1 and 1 is d = 1 is selected.

In the reproduction equalization, when the circuit system shown in FIG. 7 is used,
The target channel characteristic is 1 + D−D ² −D ³ or 1
+ Called EPR or E represented by 2D-2D ⁴ -D ⁵
EPR is selected. Here, D is a delay operator indicating a delay corresponding to the bit interval of the read signal. Decision feedback in Figure 8 also be expressed in this form, the target channel characteristics FFF is ^{1 + k1D + k2D 2 + k3D} 3 +. . . It is. Here, k1, k2, k3, etc. are coefficient values.

Since the allowable circuit scale increases with the progress of the semiconductor fine process, the present invention is not limited to the above-described example, and even if a more complicated target channel characteristic is selected, it is within the scope of the present invention. Needless to say,

Further, in the above embodiment, the condition of the presence of the nonlinear bit shift and the condition that there is a signal inversion immediately before is described. However, for more accurate recording compensation, another condition in the recording code is detected. , Predetermined recording compensation may be performed. This can easily be inferred, and these are also within the scope of the present invention.

Further, in this embodiment, a case is assumed in which the in-plane and the perpendicular recording are combined, but when the transition to the perpendicular recording is completely made, the recording compensation only for the perpendicular recording is performed. Are also within the scope of the present invention.

[0032]

According to the present invention, it is possible to provide a signal processing semiconductor device which can be used in common for both magnetic disks incorporating an in-plane or a perpendicular recording medium, so that the device cost is greatly reduced by mass production. Probability is high. In addition, since the in-plane and perpendicular recording media can be evaluated by the common signal processing device according to the present invention, the accuracy of the evaluation is increased and the selection of the recording medium is facilitated. Contribute to reducing development costs.

[Brief description of the drawings]

FIG. 1 is a processing system diagram of a recording signal according to an embodiment of the present invention.

FIG. 2 is a processing system diagram of a signal on a reading side according to an embodiment of the present invention.

FIG. 3 is an explanatory diagram of a nonlinear bit shift.

FIG. 4 is a logic circuit diagram of a bidirectional recording compensating means of the present invention.

FIG. 5 is a signal waveform diagram of each part in FIG.

FIG. 6 is a logic circuit diagram of another embodiment of the bidirectional recording compensation means.

FIG. 7 is a circuit block diagram showing an example of a reproducing equalizer suitable for the present invention.

FIG. 8 is a circuit block diagram of another embodiment of the reproducing equalizer suitable for the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Recording encoding means, 2 ... Bidirectional recording compensation means, 3 ... Recording amplification means, 4 ... Recording medium, 5 ... Reproduction amplification means, 6 ... Reproduction equalization means, 7 ... Detection means, 8 ... Decoding means.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihisa Nakamura 1-2-2, Shoai, Izumi-ku, Sendai, Miyagi Prefecture (72) Inventor Hiroaki Muraoka 5-7-1, 502F, Koriyama 6-chome, Taishiro-ku, Sendai City, Miyagi Prefecture Terms (Reference) 5D031 BB01 BB02 CC03 DD01 EE01 HH01

Claims (11)

[Claims] 1. A signal processing device for recording a digital signal on a magnetic recording medium using a recording encoding means, wherein the signal processing device has a setting portion for designating a recording medium to be used. 2. The signal processing device according to claim 1, wherein said magnetic recording medium is an in-plane recording medium or a perpendicular recording medium. 3. The signal processing device according to claim 1, wherein in the signal processing device, the signal processing on the reproduction side uses the same signal processing configuration irrespective of the recording medium. 4. The signal processing device according to claim 1, wherein the recording encoding means is recording encoding in which the minimum number d of 0s included between 1 and 1 in recording encoding according to the NRZI rule is d = 1. 2. The signal processing device according to claim 1, wherein 5. A signal processing device for recording a digital signal on a magnetic recording medium using a recording encoding means, in which a recording signal satisfies a certain condition, a bidirectional recording compensation which can be advanced and delayed with respect to a normal signal inversion position. A signal processing device characterized by using means. 6. The signal processing device according to claim 5, wherein said magnetic recording medium is an in-plane recording medium or a perpendicular recording medium. 7. The signal processing device according to claim 5, wherein in the signal processing device, the signal processing on the reproduction side uses the same signal processing configuration irrespective of the recording medium. 8. The signal processing device according to claim 1, wherein the recording encoding means is recording encoding in which the minimum number d of 0s included between 1 and 1 in the recording encoding of the NRZI rule is d = 1. The signal processing device according to claim 7, wherein 9. A signal processing device for recording a digital signal on a perpendicular magnetic recording medium using a recording encoding means,
A signal processing device characterized by using a recording compensator which can precede a normal signal inversion position when a recording signal satisfies a certain condition. 10. The signal processing device according to claim 1, wherein the recording encoding means is recording encoding in which the minimum number d of 0s included between 1 and 1 in recording encoding of the NRZI rule is d = 1. 10. The signal processing device according to claim 9, wherein 11. A digital signal recording apparatus using the signal processing device according to claim 1.