JPH04111205A - Digital magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To reduce pattern peak shift due to waveform interference between bits by deciding data by providing a waveform equalization circuit and detecting the zero cross point of a waveform equalizing output signal. CONSTITUTION:A waveform equalizing means 4 is provided in which a magnetic flux response type reproducing head 2 by which the reproducing output signal of a waveform that almost coincides with magnetization distribution on a magnetic recording medium is obtained by reproducing a signal digitally recorded on the magnetic recording medium is used, and furthermore, the waveform equalizing output signal in which the inclination of a waveform in accordance with the reversal of magnetization on the magnetic recording medium 1 of the reproducing output signal from the magnetic flux response type reproducing signal is steepened can be obtained. The zero cross point of the waveform equalizing output signal is detected, and data decision is performed. In such a way, it is possible to effectively reduce the pattern peak shift due to the waveform interference between the bits by generating the waveform equalizing output signal provided with a steep inversion area from the reproducing output signal with moderate waveform (inversion area) in accordance with the reversal of magnetization on the magnetic recording medium 1 from the magnetic flux response type reproducing head 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a digital magnetic recording/reproducing apparatus, and more particularly to a digital magnetic recording/reproducing apparatus using a magnetic flux responsive reproducing head.

(Prior Art) Digital magnetic recording is a method in which binary digital information of "1" and "0" is saturated recorded as a predetermined magnetization reversal series on a magnetic recording medium, and is used in digital magnetic recording and reproducing devices such as magnetic disk devices. It is used in Conventional digital magnetic recording and reproducing devices generally use a magnetic flux induction type ring head to reproduce signals recorded on a magnetic recording medium. In this method, the reproduced signal from the magnetic flux induction head is differentiated, a data judgment window is formed, and data "12 "0" is judged based on the presence or absence of a zero-crossing point of the differential output signal within the window. However, In this method, a pattern peak shift occurs due to waveform interference during high-density recording, which poses a problem in realizing high-density recording.

Various waveform equalization methods have been proposed to reduce pattern peak shifts caused by such waveform interference. For example, Japanese Patent Laid-Open No. 83-53761 discloses that by adding the differential waveform and integral waveform of the reproduced output signal from an inductive ring head after performing appropriate gain adjustment, even a system with low resolution can generate patterns due to waveform interference. An equalization method that can reduce peak shift is shown. Since this method uses an integrating circuit, it has the following drawbacks.

When an ideal integrating circuit is used, the low frequency components are amplified in inverse proportion to the frequency, so if there is a finite amount of noise in the low frequency range, the noise output of the integrating circuit will be calculated to diverge to infinity. Put it away. Although it is impossible to realize an ideal integrating circuit in reality, when designing an actual circuit, it is necessary to cut low-frequency components from the viewpoint of S/N. However, when determining the zero-crossing point of the reproduced signal using an integrating circuit that cuts such low-frequency components, the DC
There was a dilemma in that fluctuations in the zero level directly led to fluctuations in the zero cross position. Furthermore, if a C component is superimposed to a large extent due to external noise, there is a possibility that the DC component will accumulate by performing integration.

Furthermore, when a magnetic flux guiding head is used as a reproducing head, the level of the obtained reproducing output signal is proportional to the relative speed between the reproducing head and the recording medium.

Therefore, if the relative speed changes, the reproduced output signal will not only change on the time axis but also change in signal level. In such a case, it is difficult to correctly reproduce data from the reproduced output signal using the conventional method. In order to stably obtain a predetermined playback output signal level, it is relatively easy to maintain a constant relative speed between the playback head and the recording medium in magnetic disk drives, but it is In card processing systems, it is necessary to run cards at high speed and at a constant speed, which makes the device complicated and large.

(Problems to be Solved by the Invention) As described above, in conventional digital magnetic recording and reproducing devices, in order to reduce pattern peak shifts, the differential waveform and integral waveform of the reproduced output signal from the inductive ring head are adjusted to an appropriate gain. The method of performing addition after adjustment has a problem in that when determining the zero-crossing point of the reproduced signal, the zero-crossing position directly changes due to fluctuations in the DC zero level, so correct data determination cannot be made.

Furthermore, when a magnetic flux induction head is used as a playback head, the level of the playback output signal fluctuates in proportion to the relative speed between the playback head and the recording medium, so in order to correctly reproduce data from the playback output signal, the relative speed must be adjusted. It had to be kept constant, which caused the device to become complicated and large.

The present invention solves the problems of the prior art described above,
A first object of the present invention is to provide a digital magnetic recording/reproducing device that can effectively reduce pattern peak shifts without using an integrating circuit.

A second object of the present invention is to provide a digital magnetic recording and reproducing apparatus that can stably reproduce data even when there are fluctuations in the relative speed between the reproducing head and the recording medium.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the first object, the present invention reproduces a signal digitally recorded on a magnetic recording medium to substantially match the magnetization distribution on the magnetic recording medium. Waveform equalization is performed by using a magnetic flux-responsive reproducing head that obtains a reproducing output signal with a waveform that is similar to that of the magnetic flux-responsive reproducing head, and further steepening the slope of the waveform corresponding to the magnetization reversal on the magnetic recording medium of the reproducing output signal from the magnetic flux-responsive reproducing head. The present invention is characterized in that it includes a waveform equalization means for obtaining an output signal, and that data determination is performed by detecting zero crossing points of the waveform equalized output signal.

The waveform equalization means, for example, applies second-order differentiation to the reproduced output signal and combines the differentiated output signal and the reproduced output signal with a predetermined relative amplitude, or differentiates the reproduced output signal and combines the differentiated output signal and this. A signal obtained by combining a signal delayed by a predetermined amount and a reproduced output signal with a predetermined relative amplitude, or a signal obtained by combining a reproduced output signal and a signal delayed by a predetermined amount with opposite polarity, and a reproduced output signal. A waveform-equalized output signal is generated by combining the signal and the signal delayed by a predetermined amount with a predetermined relative amplitude.

In addition, as another means of waveform equalization, a magnetic flux induction type recording/reproducing head is used in addition to the magnetic flux response type reproducing head, and signals digitally recorded on a magnetic recording medium are reproduced by the magnetic flux induction type recording/reproducing head. Differentiate the reproduced output signal,
By combining this differential output signal and the reproduced output signal from the magnetic flux responsive read head with a predetermined relative amplitude, a waveform of the reproduced output signal from the magnetic flux responsive read head corresponding to magnetization reversal on the magnetic recording medium is generated. The slope may be made steeper.

In order to achieve the second object, the present invention provides a digital magnetic recording and reproducing apparatus for digitally recording and reproducing signals including data bits and clock bits on a magnetic recording medium, in which a plurality of magnetic flux responsive reproducing heads are used as part of a magnetic recording medium. The present invention is characterized in that when a head detects a data bit, some other heads are arranged to detect a clock bit almost at the same time.

(Operation) - In this way, a waveform equalized output signal having a steep reversal region is generated from a reproduction output signal with a gentle waveform (reversal region) corresponding to the magnetization reversal on the magnetic recording medium from the magnetic flux responsive reproducing head. By doing so, pattern peak shifts due to waveform interference between bits are effectively reduced.

In addition, by arranging multiple magnetic flux-responsive playback heads so that when some heads detect data bits, other heads detect clock bits almost simultaneously, the playback heads and magnetic recording Stable data reproduction can be performed even when there are fluctuations in the relative speed with the medium.

(Embodiment) FIG. 1 is a block diagram showing the configuration of a reproduction system of a digital magnetic recording and reproduction apparatus according to a first embodiment of the present invention.

In FIG. 1, a magnetic recording medium 1 is, for example, a magnetic disk, and has already been used for digital recording, that is, "1", "0"
It is assumed that a binary digital signal is recorded in saturation in the form of a magnetization reversal series. Signals digitally recorded on this magnetic recording medium 1 are reproduced by a magnetic flux responsive reproducing head 2. In this case, the reproduction output signal from the magnetic flux-responsive reproduction head 2 has a waveform that approximately conforms to the magnetization distribution of the magnetic recording medium 1. ) shall be specified.

The reproduction output signal from the reproduction head 2 is amplified by an amplifier 3, subjected to waveform equalization by a waveform equalization circuit 4, and then inputted to a zero-cross detection circuit 5 to detect a zero-cross point. The output of the zero cross detection circuit 5 is further input to a data determination circuit 6. The data judgment circuit 6 uses a predetermined data judgment window and checks whether there is a zero-crossing point detected by the zero-crossing detection circuit 5 within the window to judge whether the data is "1" or "0'" and outputs the judgment result. Send to terminal 7.

The waveform equalization circuit 4 is a circuit that generates a waveform equalized output signal in which the waveform of the reversal region (magnetization reversal region on the magnetic recording medium 1) of the reproducing output signal from the magnetic flux responsive reproducing head 2 is steepened. , in this example, a second-order differential circuit 11, an amplifier 12,
It is composed of a delay circuit 13 and an adder circuit 14. That is, the reproduced output signal from the magnetic flux response type reproducing head 2 inputted to the waveform equalizing circuit 4 by the amplifier 3 is partially branched,
One signal is second-order differentiated by a second-order differentiation circuit 11 .

The output signal of the second-order differentiating circuit 11 is input to the inverting input terminal of the adder circuit 14 via an amplifier 12 for amplitude adjustment. The other partially branched signal is input to the non-inverting input terminal of the adder circuit 14 via the delay circuit 13 for phase adjustment. The adder circuit 14 subtracts the output signal of the amplifier 12 from the output signal of the delay circuit 13, that is, synthesizes the reproduction output signal from the magnetic flux responsive reproduction head 2 and its second-order differential output signal with a predetermined relative amplitude. , obtain a waveform equalized output signal. The delay circuit 13 is used to match the timing of the two inputs of the adder circuit 14, and its delay time is set to be approximately equal to the total delay time of the second-order differentiator circuit 11 and the amplifier 12, for example.

FIG. 2 is a diagram showing waveforms at various parts when an isolated magnetization reversal region on the magnetic recording medium 1 is reproduced with the configuration shown in FIG.
) is the waveform of the output signal f(t) of the delay circuit 13, (b)
is the waveform of the output signal f'(t+τ) of the amplifier 12, and (c) is the waveform of the waveform-equalized output signal output from the adder circuit 14 that combines (a) and (b). However, τ is the delay time of the delay circuit 13. Further, in this example, the gain K of the amplifier 12 is set to -0.6.

In this way, by subtracting the second-order differential output signal after adjusting it to an appropriate amplitude from the reproduced output signal having a gradual reversal region obtained by the magnetic flux responsive reproducing head 2, a waveform having a steep reversal region can be obtained. A waveform equalized output signal can be created. Therefore, when this waveform-like signal is subjected to data determination through the zero-cross detection circuit 5 and the data determination circuit 6, pattern peak shifts due to waveform interference between bits can be reduced.

FIG. 3 shows a waveform equalization circuit 4 in a second embodiment of the present invention.
FIG. 2 is a block diagram showing the configuration of FIG. The waveform equalization circuit 4 shown in FIG. 3 is composed of a differentiating circuit 21, a delay circuit 22 for phase adjustment, an addition circuit 23, an amplifier 24 for amplitude adjustment, a delay circuit 25 for phase adjustment, an amplifier 26, and an addition circuit 27. has been done.

That is, the reproduction output signal from the magnetic flux responsive reproduction head 2 inputted from the amplifier 3 is partially branched, and one signal is inputted to the differentiating circuit 21.

From the differentiated output signal of the differentiating circuit 21, a signal obtained by delaying this differentiated output signal by the delay circuit 22 is subtracted in the adding circuit 23, and the output signal of the adding circuit 23 is further subtracted from the differentiated output signal by the amplifier 24.
After being amplified, the signal is input to one input terminal of the adder circuit 27. The other partially branched signal is input to the other input terminal of the adder circuit 27 via a delay circuit 25 for phase adjustment and an amplifier 26 for amplitude adjustment.

FIG. 4 is a diagram showing the waveforms of various parts when the isolated magnetization reversal region on the magnetic recording medium 1 is reproduced with the configuration shown in FIG.
) is the waveform of the output signal f (t) of the amplifier 26, and (d) is the output signal of the amplifier 24 which is a combination of FIG. 4(b) and (c). (t-τ) waveform,
And (e) is an adder circuit 2 that combines (a) and (d).
This is the waveform of the waveform equalized output signal output from 7.

Here, τ is the delay time of the delay circuits 22 and 25, and K is the gain of the amplifier 24.

According to this embodiment as well, it is possible to convert a reproduction output signal having a gradual inversion region obtained by the magnetic flux responsive sculpting reproduction head 2 into a waveform-equalized output signal having a waveform having a steep inversion region.

FIG. 5 shows a waveform equalization circuit 4 in a third embodiment of the present invention.
FIG. 2 is a block diagram showing the configuration of FIG. The waveform equalization circuit 4 shown in FIG. 5 includes a delay circuit 31 for phase adjustment, an addition circuit 32, an amplifier 33 for amplitude adjustment, a delay circuit 34 for phase adjustment, and an addition circuit 35.

That is, the reproduced output signal from the magnetic flux responsive reproducing head 2 inputted by the amplifier 3 is partially branched, and one signal is inputted to the delay circuit 31.

The output signal of the delay circuit 31 is subtracted from the input signal in the adder circuit 32, and the output signal of the adder circuit 32 is subtracted from the input signal in the adder circuit 32.
After being amplified by step 3, the signal is input to the inverting input terminal of the adder circuit 35. The other partially branched signal is input to a non-inverting input terminal of an adder circuit 35 via a delay circuit 34 for phase adjustment.

FIG. 6 is a diagram showing the waveforms of various parts when the isolated magnetization reversal region on the magnetic recording medium 1 is reproduced with the configuration shown in FIG.
) is the waveform of the output signal f(t) of the delay circuit 34, (d)
is the waveform of −f(t+τ)+K・f (−τ) in the output signal of the amplifier 33 which is the summation of (b) and (c), and (e) is the summation of (a) and (d). This is the waveform of the waveform equalized output signal output from the adder circuit 35. here,
τ is the delay time of the delay circuits 22 and 25, and K is the gain of the amplifier 24.

According to this embodiment as well, it is possible to convert a reproduced output signal having a gradual reversal region obtained by the magnetic flux responsive reproducing head 2 into a waveform-equalized output signal having a waveform having a steep reversal region.

FIG. 7 is a block diagram showing the configuration of a reproducing system of a digital magnetic recording/reproducing apparatus according to a fourth embodiment of the present invention. In FIG. 7, a signal digitally recorded on a magnetic recording medium 41 is reproduced by a magnetic flux response type reproducing head 42 and a magnetic flux guiding type recording/reproducing head 43. 1st~
Similar to the third embodiment, the reproduction output signal from the magnetic flux responsive reproduction head 42 has a waveform that substantially conforms to the magnetization distribution of the magnetic recording medium 1. The reproduction output signals from the magnetic flux responsive read head 42 and the magnetic flux guided read/write head 43 are amplified by amplifiers 44 and 45, respectively.

The reproduced output signal from the magnetic flux induction type recording/reproducing head 43 outputted via the amplifier 45 is differentiated by a differentiating circuit 46.
The differential output signal is input to the inverting input terminal of the adder circuit 49 via an amplifier 47 for amplitude adjustment. On the other hand, the reproduced output signal from the magnetic flux responsive reproducing head 42 outputted via the amplifier 44 is inputted to the non-inverting input terminal of the adder circuit 49 via a delay circuit 48 for phase adjustment.

The output of the adder circuit 49 is input to a zero-crossing detection circuit 50, and a zero-crossing point is detected.

The output of the zero-cross detection circuit 50 is further input to a data judgment circuit 51, and the data judgment circuit 51 checks whether there is a zero-cross point detected by the zero-cross detection circuit 50 within a predetermined data judgment window. “1” or “0” is determined, and the determination result is sent to the output terminal 52.

FIG. 8 is a diagram showing the waveforms of various parts when the isolated magnetization reversal region on the magnetic recording medium 41 is reproduced with the configuration shown in FIG.
(a) shows the waveform of the playback output signal from the magnetic flux responsive playback head 42 passed through the amplifier 44 and the delay circuit 48, (b) shows the waveform of the playback output signal from the magnetic flux induction head raw head 43, and (c) shows the waveform of the playback output signal from the magnetic flux induction head raw head 43. b) is differentiated by the differentiating circuit 46 and further passed through the amplifier 47, and (d) is the waveform of the signal obtained by (a) and (C
) is the waveform of the waveform equalized output signal output from the adder circuit 49.

As described above, in this embodiment, the differential waveform of the reproduced waveform of isolated magnetization reversal obtained by the magnetic flux induction type reproducing head 43 is appropriately calculated from the reproduced output signal having a gradual reversal region obtained by the magnetic flux responsive type reproducing head 42. By subtracting based on the amplitude and phase relationship, it is possible to generate a waveform equalized output signal having a steep inversion region as in the first to third embodiments. Therefore, if this waveform equalized output signal is subjected to data determination through the zero cross detection circuit 50 and the data determination circuit 51, pattern peak shifts due to waveform interference between bits can be reduced.

9 to 14 show various magnetic heads used for magnetic recording. 9 to 11 show magnetic flux induction type heads, FIG. 9 shows a ring-shaped bulkhead consisting of a ring-shaped ferrite core 101 and a coil winding 102, and FIG. 10 shows a ring-shaped magnetic thin film core 103 and a thin film FIG. 11 shows a ring-shaped thin film head consisting of a coil 104, and a magnetic flux induction type single pole head consisting of a single magnetic thin film core 105 and a coil winding 106.

12(a), (b), and (c) show the classification of magnetoresistive heads (MR heads), which are magnetic flux responsive heads. (b) A shielded MR head in which the MR element 111 is covered with a shield 112; (e) A yoke-type MR head having a yoke 113.

Figure 13 shows four examples of non-shielded MR heads.
A detection current is supplied to the MR element 111 through the conductor 114 .

FIG. 14 shows an example of an improved yoke MR head that operates in a differential type, in which two MR elements 111A and IIIB are provided between a front yoke 115 and a back yoke 116, and the signal magnetic field from the magnetic recording medium 110 is The resistance value change in the opposite direction of both MR elements 111A and IIIB due to +ΔR1−
ΔR is detected differentially to perform highly sensitive reproduction.

FIG. 15 shows an example of a head/medium system suitable for the present invention together with a conventional example and a reproduction waveform of isolated magnetization reversal. 1st
5(a) shows the longitudinal magnetic recording medium 51 and the inductive ring head 52, FIG. 15(b) shows the perpendicular magnetic recording medium 53 and the inductive ring head 52, and FIG. 15(C) shows the longitudinal recording medium 5.
] and the inductive vertical head 54, FIG. 15(d) shows the perpendicular magnetic recording medium 53 and the inductive vertical head 54, FIG. 15(e)
is the longitudinal magnetic recording medium 51 and the MR head 55, FIG.
are the perpendicular magnetic recording medium 53 and the MR head 55, FIG.
g) shows a longitudinal magnetic recording medium 51 and a yoke-type MR head 56.
, FIG. 15(h) shows the perpendicular magnetic recording medium 53 and the yoke type M
Each combination of R heads 56 is shown. Among these, in the cases shown in FIGS. 15 (cl) and (g), a reproduction output waveform corresponding to the magnetization pattern on the magnetic recording medium is obtained, and the magnetic flux responsive reproduction in the first to fourth embodiments described above is obtained. Can be used as a head.

The playback head/medium combinations illustrated here are as follows:
There are no limitations on the combinations of playback heads and media that can be applied to the present invention. Regardless of the recording principle, the reproduction principle, or the magnetization direction of the medium, if the reproduction waveform is a waveform that substantially corresponds to the medium magnetization, the above case can be applied. For example, in addition to the MR head, a so-called active head that utilizes changes in high-frequency magnetic permeability caused by a Hall element or a magnetic field may be used as the reproducing head.

FIG. 16 shows a synthesized waveform from the original waveform of the reproduction output signal from the reproduction head and its second-order differential waveform (or the differential waveform of the reproduction output signal from the magnetic flux-guided reproduction head) in the first to fourth embodiments, i.e. FIG. 3 is a diagram for explaining a gain setting method of amplifiers (12, 24, 33, 47, etc.) when producing a waveform equalized output signal. When the amplitude of the isolated waveform of the original waveform in FIG. 16(a) is normalized to +1 to -1, from the viewpoint of reducing the pattern peak shift, adjacent magnetization reversal positions in the composite waveform in FIG. 16(b) (A,
By setting the values at A'' to be +1.-1 on the left and right sides of the origin, the pattern peak shift can be made zero in a pattern that includes the minimum magnetization reversal with the largest pattern peak shift.

Furthermore, it is preferable to set the gain of the amplifier 12, for example in the case of FIG. 1, taking into account not only the pattern peak shift but also the fluctuation of the zero crossing point due to noise. Further, when the gain of the amplifier 12 is set to be constant and used in a case where the resolution differs depending on the track position as in a magnetic disk device, it is preferable to find the optimum value of the gain at the inner and outer circumferences and set it to that value.

FIG. 17 shows an example of a magnetic disk device to which the present invention can be applied, in which a plurality of magnetic disks 201 are stacked at predetermined intervals, and a magnetic head 202 faces them. The magnetic head 202 is provided on a head slider 203 as shown in FIGS. 18(a) and 18(b). In FIG. 18(a), a composite head 204 which is a combination of a recording head and a reproducing head is used, and in FIG. 18(b), a recording head 205 and a reproducing head 206 which are individually configured are used.

FIG. 19 shows a fifth example in which the present invention is applied to a card processing system.
(a) shows a magnetic card 61 as a magnetic recording medium, (b) is a side view of the main parts of the digital recording and reproducing device, and (C) shows the magnetic card and the reproducing head. It shows the positional relationship. A magnetic card 61 is inserted through a card insertion slot 62, and the data recorded in FM on its data track 63 is transferred to first and second magnetic flux response type reproducing heads 64 disposed along the running direction of the magnetic card 61. Reproduced by .65.

Here, the first and second magnetic flux responsive read heads 64 .
The interval 65 is set to an odd multiple of the minimum magnetization reversal interval recorded on the magnetic card 61. That is, when the head 64 is reading the data bit (d in FIG. 19), the head 65 is reading the clock bit (c in FIG. 19).
conversely, when the head 64 is reading the clock bit, the head 65 is in a positional relationship to read the data bit. Therefore, the data recorded on the magnetic card 61 can be reproduced by determining the presence or absence of data bit magnetization reversal in synchronization with the tarok signal.

Furthermore, since the present embodiment uses magnetic flux response type reproducing heads 64 and 65 as the reproducing head, the magnitude of the reproduced output signal does not depend on the relative speed of the head and the medium.
Even if there is a change in the relative speed between the head and the medium, there is no change in the magnitude of the reproduced output signal. Furthermore, the phase relationship between the data bit and the clock bit also depends only on the spatial relationship between the two magnetic flux responsive read heads 64 and 65.
It does not depend on the relative velocity of the head and media.

As described above, according to this embodiment, even if the conveying speed of the magnetic card 61 fluctuates, it is possible to stably detect the reproduced output signal. Thereby, by providing a reversal prevention roller 65 close to the card insertion slot 62 that operates only when a card is inserted, it is also possible to read data by manual conveyance. Furthermore, in a system where the fluctuation in conveyance speed is small, it is also possible to adjust the phase relationship between the two reproduced signals using a delay line.

A method for determining whether data bits are synchronized or asynchronous with respect to a clock bit is to form a window having a width of a certain time before and after the clock bit is detected, and determine whether or not a data bit falls within this window. The width of this window may be fixed, but if the conveyance speed of the magnetic card 61 fluctuates greatly, it is preferable to make it variable according to the value of the conveyance speed measured from the clock bit interval or the like.

Furthermore, since the apparatus of this embodiment uses a magnetic flux response type reproducing head 64, 65 in which the level of the reproduced output signal is stable regardless of the relative speed of the head and the medium, the magnetic card 61
Since there is no need to transport the magnetic card 61 at a high and constant speed, not only can the device be made more compact, but it is also possible to eject the magnetic card 61 from the card insertion slot 62 in the direction in which it was inserted. In an apparatus that performs both recording and reproduction, a compact apparatus can be provided by, for example, reading when inserting and writing when ejecting. The fact that the running direction of the card is reversed can be handled by storing the data either during reading or ejection in an appropriate buffer memory and reversing the order of the data string. Furthermore, instead of transporting the magnetic card 61, recording and reproduction can be performed by storing and fixing the magnetic card 61 in the device and then driving the heads 64 and 65.

In this embodiment, it is preferable that the two reproducing heads 6465 be integrated so that the relative spacing can be maintained constant. In addition, it is preferable that the distance between the two read heads 64 and 65 be as close as possible in order to avoid the influence of expansion and contraction due to temperature and humidity of the magnetic card 61. It should be determined by taking into account mutual magnetic interference between .64 and .64.

FIG. 20 shows a sixth embodiment in which the present invention is also applied to a card processing system, and similarly to FIG.
) shows a magnetic card 71 as a magnetic recording medium, and (b
) is a side view of the main parts of the digital recording and reproducing apparatus, and (c) shows the positional relationship between the magnetic card and the reproducing head. On the magnetic card 71, there is a data track 7 for recording data.
2 and a clock track 73 for recording a clock signal synchronized therewith.

The magnetic card 71 is inserted from the card insertion lower 4, and the data recorded on the data track 72 of the magnetic card 71 is reproduced by a first magnetic flux responsive reproducing head 75 disposed in the data track traveling direction. magnetic card 7
The tarok recorded on one clock track 73 is reproduced by a second magnetic flux responsive reproducing head 76 disposed in the clock track running direction.

The subsequent signal reproduction can be performed in the same manner as in the embodiment shown in FIG. If card skew may occur, it is possible to correct the skew by providing a plurality of clock tracks and averaging them.

E. Effects of the Invention] As described above, according to the present invention, it is possible to synthesize a waveform equalized output signal having a steep reversal region from a magnetic flux responsive head reproduction output signal waveform having a gradual reversal region, and By detecting zero crossing points of the waveform equalized output signal and determining data, it is possible to reduce pattern peak shifts due to waveform interference between bits.

Furthermore, unlike the prior art, the present invention does not require an integrating circuit, so the dilemma regarding the DC component does not occur in principle.

Furthermore, since a magnetic flux responsive magnetic head is used as the playback head, the level of the playback output signal does not depend on the relative speed of the head and the medium, it is possible to achieve high recording speeds in small-diameter magnetic disk drives and magnetic tape drives where the relative speed of the head and the medium is low. Suitable for achieving density.

Furthermore, according to the present invention, when a plurality of magnetic flux responsive read heads are used and some of the heads detect data bits,
By detecting the clock bits by some of the other heads at approximately the same time, stable data reproduction can be performed even when there is a fluctuation in the relative speed of the head and the medium. Furthermore, when the present invention is applied to a magnetic card processing system, it is possible to omit the mechanism and space required to transport the card at a high and constant speed for writing to and reading from the magnetic card. It has a great effect on compactness and cost reduction.

Further, the digital magnetic recording/reproducing apparatus according to the present invention is suitable for use in combination with an MR head or active head, which is a highly sensitive read head, and also with a perpendicular magnetic recording medium that is inherently capable of high-density recording. This makes it possible to bring out the full potential of these heads and media.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a digital magnetic recording and reproducing apparatus according to a first embodiment of the present invention, FIG. 2 is a waveform diagram of each part in FIG. 1, and FIG. 3 is a block diagram of a digital magnetic recording and reproducing apparatus according to a second embodiment of the present invention. A block diagram of a digital magnetic recording/reproducing apparatus, FIG. 4 is a waveform diagram of each part in FIG. 3, FIG. 5 is a block diagram of a digital magnetic recording/reproducing apparatus according to a third embodiment of the present invention, and FIG. The waveform diagram of each part in FIG. 5, and FIG.
FIG. 8 is a block diagram of a digital magnetic recording/reproducing apparatus according to an embodiment of the present invention. FIG. 8 is a waveform diagram of each part in FIG. 7. FIGS. FIG. 15 is a diagram showing reproduction output signal waveforms of various combinations of a reproduction head and a magnetic recording medium and isolated magnetization reversal, and FIG. 16 shows a method of adjusting the gain of an amplifier in the first to fourth embodiments of the present invention. FIG. 17 is a perspective view showing a magnetic disk device to which the present invention can be applied;
8 is a perspective view showing the configuration of the magnetic head in FIG. 17, FIG. 19 is a diagram for explaining a fifth embodiment in which the present invention is applied to a card processing system, and FIG. 20 is a perspective view showing the structure of the magnetic head in FIG. It is a figure for explaining the 6th example applied to a processing system. 1... Magnetic recording medium (magnetic disk) 2.41...
Magnetic flux responsive magnetic head 4... Waveform equalization circuit 5.50... Zero cross detection circuit 6.51... Data judgment circuit 11... Second order differential circuit 12.24, 33.47... Amplitude adjustment amplifier 1B,
22, 25, 31, 34.48 ... Delay circuit for phase adjustment 14.23, 27, 32, 35.49 ... Addition circuit 42 ... Flux induction type magnetic head 61.71 ... Magnetic recording Medium (magnetic card) 63.7
2...Data track 64.65, 75.76...Flux responsive magnetic head 73...Clock track Applicant's representative Patent attorney Takehiko Suzue Figure 2-K -f'(t+t) 10K ・f '(t-T
) Fig. 10 - f (t-1) Fig. 10 Fig. 11 Fig. 12 Fig. 15 Fig. 13 Fig. 14 Fig. 16 Recording head 205 Fig. 17 (b) Figure 18 (b) (C) Figure 19

Claims (6)

[Claims] (1) a magnetic flux responsive reproducing head that reproduces a signal digitally recorded on a magnetic recording medium to obtain a reproduced output signal having a waveform that substantially matches the magnetization distribution on the magnetic recording medium; and the magnetic recording of the reproduced output signal. A waveform equalizing means for obtaining a waveform equalized output signal with a steeper waveform slope corresponding to magnetization reversal on the medium, and a means for detecting a zero crossing point of the waveform equalized output signal and determining data. A digital magnetic recording/reproducing device characterized by: (2) The waveform equalizing means includes means for obtaining a differential output signal by performing second-order differentiation on the reproduced output signal, and a means for obtaining a differential output signal by performing second-order differentiation on the reproduced output signal, and combining the differential output signal and the reproduced output signal with a predetermined relative amplitude to form the waveform. 2. The digital magnetic recording and reproducing apparatus according to claim 1, further comprising means for obtaining an equalized output signal. (3) The waveform equalization means includes means for differentiating the reproduced output signal to obtain a differentiated output signal, a signal obtained by combining the differentiated output signal and a signal delayed by a predetermined amount, and the reproduced output signal. 2. The digital magnetic recording and reproducing apparatus according to claim 1, further comprising means for obtaining said waveform equalized output signal by synthesizing said waveform equalized output signals with a predetermined relative amplitude. (4) The waveform equalization means combines a signal obtained by combining the reproduced output signal and a signal delayed by a predetermined amount with opposite polarity, and a signal obtained by delaying the reproduced output signal by a predetermined amount, with a predetermined relative amplitude. 2. The digital magnetic recording and reproducing apparatus according to claim 1, wherein the waveform equalized output signal is obtained by performing the following steps. (5) a magnetic flux responsive reproducing head which reproduces signals digitally recorded on a magnetic recording medium to obtain a reproduced output signal having a waveform substantially matching the magnetization distribution on the magnetic recording medium; a magnetic flux induction type recording/reproducing head for reproducing a signal to obtain a reproduced output signal having a waveform substantially matching the magnetization distribution on the magnetic recording medium; and a differential output for differentiating the reproduced output signal from the magnetic flux induction type recording/reproducing head. means for obtaining a signal, and combining the reproduced output signal from the magnetic flux responsive read head and the differential output signal with a predetermined relative amplitude, the reproduced output signal from the magnetic flux responsive read head on the magnetic recording medium. The present invention is characterized by comprising means for obtaining a waveform equalized output signal with a steeper slope of the waveform corresponding to the above magnetization reversal, and means for detecting a zero crossing point of the waveform equalized output signal and determining data. A digital magnetic recording and reproducing device. (6) In a digital magnetic recording and reproducing device that digitally records signals including data bits and clock bits on a magnetic recording medium and reproduces them, when some heads detect data bits, other heads almost simultaneously 1. A digital magnetic recording and reproducing apparatus comprising a plurality of magnetic flux responsive reproducing heads arranged such that the heads detect clock bits.