JPS6353761A - Reproducing system for digital magnetic recording information - Google Patents

Abstract

PURPOSE:To improve the reliability of a device, and to obtain write data with high density, by supplying a magnetic head detecting signal to a differentiation circuit, and an integration circuit, subtracting an output signal on one side from the output signal on the other side, supplying a result to a zero-cross detection circuit, and performing the reproduction of a digital information signal based on the above output signal. CONSTITUTION:After the magnetic head detecting signal A passing an amplifier 2 is supplied to the differentiation circuit 4, and an incomplete integration circuit 7', and the output signal on one side is subtracted from the output signal on the other side, a subtraction signal D is supplied to the zero-cross point detection circuit 5 using an OV comparator, and the reproduction of the digital information signal is performed based on the output signal, and also, the output signal of a low frequency information correction circuit 14 consisting of an amplitude control circuit 11 which sets the head detecting signal A as an input signal, an amplitude control OV comparator 12, and a filter 13, is added on the subtraction signal D. In this way, it is possible to improve recording density because the error of a bit of position information due to peak shift can be eliminated, and also, since performance is not affected by the resolution of a head-medium system, it is possible to attach degree of freedom on the design of a head-medium, thereby, to improve the reliability of the device.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a reproduction method for reproducing digital magnetic recording information recorded on a magnetic recording tape, magnetic recording disk, etc. using a magnetic flux mR type magnetic head. It is something.

[Prior art and its problems]

In a digital magnetic recording/reproducing device using a conventional magnetic flux induction type magnetic head, such as a floppy disk drive device (hereinafter referred to as FDD), written digital information is read from a detection signal A by a magnetic head l, as shown in Fig. 1. When demodulating, the head detection signal A reproduced by the magnetic head is amplified by an amplifier, unnecessary high frequency components are cut off by the low-pass filter 3, and then the differential circuit 4
After differentiating it through
In modulation methods based on ZI modulation (MFM modulation, FM modulation, 2-7 conversion, etc.), the positions of each bit of the clock data string theoretically match, so the write operation is performed based on the detected signal. I am trying to demodulate the data. That is, the detection signal is demodulated through the waveform shaping circuit 6.

In the above conventional digital magnetic recording/reproducing device, the magnetic head detection signal A is passed through the differentiating circuit 4 in order to detect the rising point of write data. '＋P2
' causes a shift due to head and media resolution and data clock pattern.

FIG. 2 illustrates an example of this. Let Wl be the input signal waveform when only the IP bit of write data is present, and W2 be the input signal waveform when only 2P bits of write data are present. The signal waveform W is a composite waveform of Wl and W2, and its peak value position P I '+
Pg' is shifted left and right by α or β, respectively, as shown.

The amount and direction of this peak shift change depending on the write data pattern and recording density, but if there is a peak shift, the bit interval of the reproduced signal will be different from the bit interval of the write data. This lowers the reliability of the digital magnetic recording/reproducing device and prevents higher density of write data to be written on a floppy disk (hereinafter referred to as FD).

In addition, according to the conventional method, depending on the design value of the differentiating circuit, there may be a depression (called a saddle) in the differential waveform on the low density side.
A protection circuit was required to prevent the comparator from erroneously detecting this as a data bit.

Therefore, the present invention aims to provide a reproduction method that can obtain a reproduction signal of written digital information without zero-crossing point shift.

[Means for solving problems]

The present invention has been made to solve the above-mentioned problems, and as shown in FIG.
After subtracting the output signal of that one from the other,
The subtracted signal is applied to a zero-crossing point detection circuit 5 using an OV comparator, and a digital information signal is reproduced based on the output signal of this zero-crossing point detection circuit 5. In addition, in Fig. 3, 6 is a waveform shaping circuit, 8.9
10 is an amplitude fixing circuit, and 10 is a subtracting circuit, which subtracts the output signal C of the integrating circuit 7 from the output signal B of the differentiating circuit 4 in this figure, but the reverse may be used.

According to this method, as shown in Figure 4 +dl,
Since the integral waveform of the head signal is shifted in the opposite direction to the differential waveform of the head signal, by performing subtraction, correct position information without any shift can be obtained, and by converting it into a data string, highly accurate writing can be performed. A reproduction signal of digital information can be obtained.

Furthermore, even if a saddle occurs in the differential waveform, the saddle is eliminated, so a highly accurate reproduction signal can be obtained.

However, when this method is put to practical use, the integrating circuit used for the above purpose is expensive and prone to drift, making it impractical.

Therefore, the present invention has devised a method of using an incomplete integrating circuit which has a simple structure and can be obtained at low cost instead of an integrating circuit.
That's what I'm trying to offer here.

[Embodiment 1] FIG. 5 shows an embodiment of the present invention, in which the magnetic head detection signal A passed through the amplifier 2 is applied to the differentiating circuit 4 and the incomplete integrating circuit 7' as necessary. After subtracting the output signal of the other from the output signal of the other, the subtracted signal is given to a zero-crossing point detection circuit 5 using a D-t-OV comparator, and a digital information signal is reproduced based on the output signal of this zero-crossing point detection circuit 5. At the same time, the output signal of a low frequency information correction circuit 14 comprising an amplitude control circuit 11 which receives the head detection signal A as an input signal, an amplitude control OV comparator 12, and a filter 13 is added to the subtraction signal. This is what I did.

That is, as mentioned above, if a method is adopted in which an incomplete integrating circuit is used instead of an integrating circuit, the above-mentioned problem is solved, but
As is well known, the incomplete integration circuit lacks low frequency information, so in the present invention, a low frequency information correction circuit 14 is added to supplement the low frequency information.

The amplitude control OV comparator 12 and the filter 13 are a DC regeneration circuit 15 that creates the DC component and low frequency component that are lost by using the incomplete integration circuit 7'.The head detection signal is used as an input signal, and the filter 13 In this case, a unique filter is used that is selected depending on the characteristics of the head and the medium.

The amplitude control circuit 11 is used to match the amplitude of the subtraction signal, and selectively controls the amplitude of the input signal output to the amplitude control OV comparator 12.

[Embodiment 2] Embodiment 1 is a DC regeneration circuit 15 of a low frequency information correction circuit.
Although the number of stages is one, it is also possible to have multiple stages (n stages). FIG. 6 shows its configuration, and the same parts as in FIG. 5 are given the same reference numerals.

When the DC reproducing circuit 15 is multi-staged in this manner, it becomes possible to obtain more accurate low-frequency information in proportion to the number of stages, and to reproduce highly accurate data bit strings.

〔Effect of the invention〕

In the conventional peak value detection method of digital magnetic recording, the recording density is limited by a peak shift that depends on the resolution of the head-medium system such as head gap length and spacing.

According to this method, it is possible to eliminate errors in positional information due to peak shifts, so recording density can be improved.

Further, since the performance is not affected by the resolution of the head-medium system, flexibility is given to the design of the head and the medium, and the reliability of the apparatus is improved.

Furthermore, since the method uses an incomplete integration circuit, a highly accurate digital magnetic recording device can be provided at low cost.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of a digital magnetic recording/reproducing device using a conventional magnetic flux induction type magnetic head, Fig. 2 is a waveform diagram for explaining the problems, and Fig. 3 is the basics of the present invention. A block diagram showing the configuration, FIG. 4 is a waveform diagram showing the operating principle, FIG. 5 is a block diagram of an embodiment of the present invention, and FIG.
The figures are block diagrams of different embodiments. 1...Magnetic induction type magnetic head 2...Amplifier 3...Low pass filter 4...Differentiating circuit 5...Zero cross point detection circuit 6...Waveform shaping circuit 7...Integrator circuit 7' ... Incomplete integration circuit 8.9 ... Amplitude fixed circuit 10 ... Subtraction circuit 10', 10'' ... Addition circuit 11 ... Amplitude control circuit 12 ... Amplitude side? IIov Comparator 13...Filter 14...Low frequency information correction circuit 15...DC regeneration circuit J Fig. 4 (Read Te'))

Claims (1)

[Claims] In a digital magnetic recording/reproducing device that uses a magnetic flux induction type magnetic head, the magnetic head detection signal A, which has passed through an amplifier as necessary, is given to a differentiating circuit and an incomplete integrating circuit, and the output signal of one is subtracted from the other. After that, the subtracted signal D is given to a zero-cross point detection circuit using an OV comparator, and a digital information signal is reproduced based on the output signal of this zero-cross point detection circuit, and amplitude control is performed using the head detection signal A as an input signal. A digital magnetic recording and reproducing apparatus using a magnetic induction type magnetic head, characterized in that an output signal of a low frequency information correction circuit comprising a circuit, an amplitude control OV comparator, and a filter is added to the subtraction signal D.