JPS62234205A - Reproducing system for digital magnetic recording information - Google Patents

Abstract

PURPOSE:To obtain a reproduced signal of high precision by subtracting an integral signal from a differential signal of the detection signal of a magnetic head to obtain zero crossing points which are not shifted and converting them to a data string. CONSTITUTION:A detection signal A from a magnetic induction type magnetic head 1 is amplified by an amplifier 2 and is applied to a differentiation circuit 4 and an integration circuit 6'. An output signal B from the circuit 4 is allowed to pass a low frequency restoring circuit 9 and a filter 10, and a corrected signal E is applied to an adder circuit 11. The signal E is added to an output signal C' from the circuit 6' by the adder circuit 11 to generate a false complete integral signal E, and this signal E is applied to a subtracter, circuit 7. An integral signal C'' is subtracted from the output signal B of the circuit 4 by the subtracter circuit 7, and the output is applied to a zero cross detecting circuit 5 through a filter. The integral signal is corrected and the false complete integral signal is obtained from the corrected signal in this manner to obtain zero crossing points which are not shifted, and they are converted to a data string, and the reproduced signal of high precision is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for reproducing digital magnetic recording information recorded on a magnetic recording tape, a magnetic recording disk, or the like.

[Conventional technology]

A digital magnetic recording/reproducing device using a conventional magnetic flux induction type magnetic head has a magnetic head 1 as shown in Fig. 1.
When demodulating the write digital information from the detection signal A by Points P+, Pz, P'l...
That is, the rising and falling points of the write data are detected, and the write data is demodulated based on the detected signals. Note that 2 is an amplifier, and 3 is a filter. [The problem that the invention seeks to solve] In the above-mentioned conventional digital magnetic recording/reproducing device, the magnetic head detection signal is passed through the differentiating circuit 4 at the rising edge of the write data. The purpose is to detect the point P1' of the peak value of the input signal waveform of the differentiating circuit 4.

p2', p, l... are caused by waveform interference (Fig. 2)
As shown in the figure, a peak shift may occur with respect to the points P, , P, , P3, . . . .

The peak shift amount and shift direction change depending on the data pattern and recording density of data writing, but if there is a peak shift, it reduces the reliability of the digital magnetic recording and reproducing device and also reduces the high quality of the write data. This hinders densification.

Furthermore, depending on the differentiator circuit design values, a saddle portion may occur in the differential waveform on the low density side, and a protection circuit is required to prevent errors caused by this.

゛ [Means for solving the problem] In view of the above points, the present invention aims to provide a reproduction method that can obtain a reproduction signal of written digital information without zero-crossing point shift, and the first invention is a case where a magnetic flux induction type magnetic head is used, and as shown in FIG. After subtracting the other output signal from the signal, the subtracted signal is applied to a zero-cross point detection circuit 5 using a comparator, and a digital information signal is reproduced based on the output signal of this zero-cross point detection circuit 5. be.

In FIG. 3, 7 is a subtraction circuit, and 8 is a filter. In this figure, the output signal C of the integrating circuit 6 is subtracted from the output signal B of the differentiating circuit 4, but the reverse may be used.

Further, the second invention is a case where a magnetic flux responsive magnetic head (MR head) 1' is used. As shown in FIG. 4, the signal is differentiated twice through differentiating circuits 4 and 4 provided in two stages, and one of the amplifier output and the second-degree differentiated signal is subtracted from the other, and then the subtracted signal is obtained. is applied to the zero-cross point detection circuit 5, and a digital information signal is reproduced based on the output signal of the zero-cross point detection circuit 5. Note that in this case as well, subtraction may be performed in reverse.

[For production]

By subtracting the differential signal and the integral signal, zero-crossing points with no shift can be obtained, and by converting them into a data string, it is possible to obtain highly accurate reproduction signals of the written digital information.

Further, even when a saddle occurs in the differential waveform, a highly accurate reproduced signal can be obtained.

〔Example〕

FIG. 5 shows an embodiment of the present invention. Since an integrating circuit is not practical due to drift, etc., an incomplete integrating circuit 6'
The correction signal E obtained by passing the output signal of the differentiator circuit 4 through the DC and low frequency restoration circuit 9 and the filter 10 is added to the output signal of the incomplete integration circuit 6' to obtain the original image complete integration signal C''. The subtraction circuit 7 subtracts the signal from the output signal of the differentiating circuit 4.

FIG. 6 (dl shows the simulation result when the magnetic head detection waveform when the write data is the data pattern "A1" of the MFM method is passed through the above reproducing circuit, and each waveform is a zero-crossing point detection diagram 5. (Comparator) This is the case when the head gap length setting value of the input is changed. In the figure, ■ is when the gap length is large, ■ is when it is medium, and ■ is when it is small. From Figure 6 (d) As can be seen, in both cases, the zero-crossing point is not shifted compared to the write data, making it an ideal detection.

FIG. 7 shows a different embodiment of the present invention, in which a comparator is used as the DC and low frequency restoration circuit 9, and the configuration is simplified by using the comparator 5 of FIG. 4. .

〔Effect of the invention〕

Traditionally, magnetic recording of digital information is based on the head gap length,
Recording density was limited by peak shifts depending on the head-medium system such as spacing, but with this method, peak shifts due to the influence of the head-medium system are eliminated, so for the same head-medium system, Higher density equipment can be realized.

Further, it is possible to realize a device in which variations in various parameters of the head-medium system do not affect reliability, and productivity can be improved, and its industrial value is extremely large.

[Brief explanation of drawings]

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 same as Fig. 1. FIG. 4 is a block diagram showing the basic configuration of the second invention. FIG. 5 is a block diagram of an embodiment of the invention. FIG. 6 is a block diagram showing the basic configuration of the second invention. A waveform diagram for explaining the effects of the example, and FIG. 7 is a block diagram of a different embodiment. ■...Magnetic induction magnetic head 2...Amplifier 3...Low pass filter 4...Differentiating circuit 5...Zero cross point detection circuit 6...Integrator circuit 7...Subtraction circuit 8...・Filter 9...DC and low frequency restoration circuit 10...Filter 11...Addition circuit Patent applicant: YE Data Co., Ltd. Agent: Osamu Hattori = ;.

Claims (2)

[Claims] (1) In a digital magnetic recording and reproducing device using a magnetic flux induction type magnetic head, the detection signal of the magnetic head is applied to a differentiating circuit and an integrating circuit, and the output signal of one is subtracted from the output signal of the other. A method for reproducing digital magnetic recording information, characterized in that a signal is given to a zero-crossing point detection circuit, and a digital information signal is reproduced based on the output signal of the zero-crossing point detection circuit. (2) In a digital magnetic recording/reproducing device using a magnetic flux-responsive magnetic head, the detection signal of the magnetic head is passed through a differentiation circuit provided in two stages, and either one of the two-stage differential signal and the detection signal is generated. A method for reproducing digital magnetic recording information, characterized in that after subtracting the other signal from the other signal, the subtracted signal is applied to a zero-crossing point detection circuit, and a digital information signal is reproduced based on the output signal of the zero-crossing point detection circuit.