JPS60124063A - Reproduction system of magnet memory device - Google Patents

Abstract

PURPOSE:To detect accurately the peak position of a reproduction signal and to improve the reliability for reproduction of a magnetic memory, by producing a gate signal which detects the peak position of the reproduction signal by a differentiation system and excludes the peak position of a signal due to noises by an integration system. CONSTITUTION:The record data is written onto a magnetic disk by a magnetic disk through a writing circuit 12, and the reproduction signal read by the head 11 is supplied to an amplifier 13. The output of the amplifier 13 is branched into two parts. One of these two outputs is supplied to a differentiating circuit 14 and differentiated; while the other output is supplied to an integration circuit 17 and integrated. This integration waveform is converted into a peak pulse PP-B via a zero-slice circuit 18, and this 2nd peak pulse PP-B is supplied to a delay circuit 19 and a triggerable monostable circuit 20 respectively. The circuit 19 delays the 2nd peak pulse by 3 bits like the input 1st peak pulse PP-A to produce a signal D. This signal D is delivered to an AND circuit 21 and a flip-flop circuit 22 respectively. A pulse NP produced by noises is excluded and only a correct signal peak pulse is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a reproduction method for a magnetic storage device.

(bl Background of the Technology) The playback method of a magnetic disk device used as an external storage device for a computer system is to differentiate the playback signal read from the magnetic disk medium and detect the peak position of the signal from the zero crossing point of the differential waveform. However, since this method has recently caused many false detections due to noise, attempts have been made to adopt an integral method that integrates the reproduced signal and detects the zero crossing point.However, this integral method When the amplitude of a signal fluctuates over a long period of time, there is a problem in detecting a position that deviates from the original peak position of the signal.For this reason, it is desired to develop a reproduction method that is resistant to noise and does not cause false detections. There is.

10) Prior art and problems FIG. 1 shows a signal waveform obtained by the above-mentioned differential method. In this figure, (81 is the reproduced signal waveform, (bl is the differential waveform of the signal, (c+ is the peak pulse detected from the intersection point of the differential waveform with the Hoeslein old 4 which is the zero crossing point, and (dl is the presence or absence of the peak pulse. In such a system, if the usage density range of the magnetic disk device is wide, the reproduced signal waveform will be Haeseline BL
Since the peak position of the signal is not the original peak position of the signal, it is erroneously detected as if the peak position of the signal exists due to the noise, and a noise pulse NP is generated. So actually,
In order to prevent erroneous peak detection due to this noise, the reproduced signal waveform itself shown in Figure 3 ia) is adjusted to an appropriate level SL.
The method used is to create a gate signal in Figure 4 (bl) and distinguish between the original peak signal and the peak signal due to noise. However, even with this method, the gate signal in Figure 4 (al
When using an asymmetric thin-film head with a pole face thickness in which the reproduced signal waveform in the low-density portion is complex as shown in Figure 2, there is a problem that the setting range of the slice level SL is narrow, and the amplitude margin AM is also small. Ta. Note that (4th appearance), [C1 and (di) indicate the differential waveform, peak pulse, and gate signal.

On the other hand, in the above-mentioned integration-based 10η2 method, in order to reproduce the same waveform as the signal waveform at the time of recording, the amplitude margin is only from the Hass line to the peak of the reproduced signal waveform.
This method has the advantage of having a larger amplitude margin than the pure amplitude detection method or the differential force method. FIG. 5 shows the signal waveform by this integration method, where (al is the recording signal waveform, (tl) is the reproduced signal waveform, (c+ is the integral waveform of the reproduced signal, and ((1
) is the peak pulse.

This integration method is usually combined with a writing method that reduces low-frequency components (for example, scrambled IIRZI).
used in The reason for this is that the playback output from the first head does not have a low frequency component. For example, in the case of a waveform that is 1-7 asymmetric with respect to Hoenelein old 7, such as the integral waveform shown in Fig. The lTr function of the component is insufficient and it becomes long.
This is to suppress this problem. In addition, Figure 6 (
81 is rlJ rOJ data for recording. but,
It is difficult to make long-period fluctuations completely zero, and when the slice level is set to zero, the peak pulse PPI and PP2 in Figure 6 (C) will shift by 8 T from the original signal peak position. A problem arises in that the peak position is detected at a certain position.

As described above, many problems remain in peak position detection using conventional reproduction methods.

(d) Object of the Invention It is an object of the present invention to provide a new reproducing method for a magnetic storage device that is resistant to noise and capable of accurately detecting the peak position of a signal.

(e) Structure of the Invention In order to achieve the above object, the present invention focuses on the advantages of conventional differentiation and integration methods, and provides a differentiation system that is resistant to amplitude fluctuations and capable of accurately detecting the peak position of a signal. A method detects the peak position of the reproduced signal, an integration method with a large amplitude margin is used to form a gate signal that excludes the peak position of the signal due to noise, and a synthesis of the signal waveforms using these methods detects the peak of the original signal. A playback method for a magnetic storage device that detects position is proposed.

Furthermore, in physical terms, the logical value r1. J.
A magnetic recorder for recording rOJ data with a magnetic head and reproducing it 1. # In the apparatus, the recorded data read by the magnetic head is passed through a differentiating circuit and an integrating circuit to form a differential waveform and an integral waveform, and the differential waveform LJ is passed through a first one-noh slice circuit and a first delay. h the circuit
The integrated waveform is converted into a peak pulse delayed by a predetermined number of bits through a 10-order pulse, and the integrated waveform is converted into a peak pulse through a second level slice circuit, and then input in parallel to a second delay circuit and a monostable circuit. The output of the stabilizing circuit and the second
The consecutive positions and time widths of "0" in the recorded data are detected by a predetermined pitch (peak pulse output delayed by several minutes) of the delay circuit, and the detected time width signal is used as a gate signal to detect the first The present invention proposes a reproducing method for a magnetic storage device, which is characterized in that pulses due to noise are extracted from a group of peak pulses from a delay circuit of the present invention.

Embodiment of the Invention Hereinafter, an embodiment of the invention will be described in detail with reference to the block diagram of FIG. 7 and the signal waveform of FIG. 8.

That is, in FIG. 7, 11 is a magnetic head, 12 is a write circuit, 13 is an amplifier, 14 is a differential circuit, 15 and 18 are zero slice circuits, ] 6 and I9 are delay circuits, 1
7 is an integrating circuit, 20 is a retriggerable monostable circuit, 21 and 23 are AND circuits, and 22 is a flip-flop circuit.

The operation of this reproducing circuit configuration will be explained together with the signal waveforms shown in FIG. 8. In this example, as is clear from FIG.
'' is shown for reproduction of recorded (written) data when 3 bins 1 or more occur consecutively. That is, the recorded data is written on the magnetic disk 2 by the magnetic head 11 through the write circuit 12, and the reproduced signal read by the magnetic head 11 is input to the amplifier 3 (see FIG. 8). The output of this amplifier 13 is branched and one of them is input to the differentiating circuit 14 and differentiated.
This differential waveform shown in FIG. These peak pulses are delayed by 3 hints in the delay circuit 16 and are shown in FIG.
becomes signal G. Note that this 3-bit signal delay is set based on the format of the write data described above.

On the other hand, the other output of the amplifier 13 is input to an integrating circuit 17 and integrated. This integral waveform shown in FIG. 8 (el) is converted into the peak pulse (second peak pulse) PP-8 shown in FIG. 8 (fl) through zero slice times 1-δ18. This second peak pulse PP-R are input to the delay circuit 19 and the retriggerable monostable circuit 20, respectively.

The delay circuit 19 delays the input signal by 3 bits in the same manner as the first peak pulse PP-A to form the signal hl shown in FIG.
Output each to 2. The retriggerable monostable circuit 20 has a response time set to approximately 2 bits in order to determine the time width of the above-mentioned 3-bit continuous "0" data. Figure (g))
A signal C shown in is obtained and output to the AND circuit 21.

The AND circuit 21 outputs a logical product signal E of these signals C and D [FIG. 8 (see i1)] to the flip-flop circuit 2.
Output to 2. The flip-flop circuit 22 is configured to be set by a signal from the delay circuit 19 to an output state of logical value "0", and reset to the original output state of "11" by a signal E from the AND circuit 21. 01 in FIG. 8 is the output waveform. The output signal F of this flip-flop circuit 22 is supplied to an AND circuit 23 as a gate signal. The AND circuit 23 also receives the signal G corresponding to the first peak pulse PP-A of the delay circuit 16 in the signal differentiation processing system, and is configured to pass this signal during the "L" state of the gate signal F. It has become. The waveform +ml in FIG. 8 shows this AND signal H, which becomes the desired peak pulse. As you will see,
Pulses NP due to noise are excluded and only peak pulses of the correct signal are detected.

Note that the above embodiment operates effectively when three or more bits of "0" are consecutive. In order to make it effective even for 2 bits or less, the response time of the retriggerable monostable circuit and the delay time of the delay circuit can be changed. However, normally when [0 () is 1 bit or 2 bits, the differential waveform hardly approaches the baseline, and therefore the probability of generation of pulses due to noise is small.

fg) Effects of the Invention As explained in detail above, according to the reproduction method of the magnetic recording device 1a of the present invention, the peak position of the reproduced signal can be detected more accurately than the conventional differential and integral methods, and is extremely effective. Highly reliable magnetic tisf devices can be realized.

[Brief explanation of drawings]

Figures 1 to 4 are signal waveform diagrams for explaining the reproduction method using the differential method of a conventional magnetic storage device, and Figures 5 and 6 are the same (for explaining the reproduction method using the conventional integral method). FIGS. 7 and 8 are a block diagram and a signal waveform diagram for explaining a specific example of the reproduction method according to the present invention. In the figure, 11 is a magnetic belly button 1', I2 is a write circuit, 1
3 is an amplifier, 14 is a differentiation circuit, 15 and 18 are zero slice circuits, 16 and 19 are delay circuits, 17 is an integration circuit, 20 is a retriggerable monostable circuit, 21 and 23 are AND circuits, and 22 is a Frisopf 11 tube circuit. Respectively, C1-〇□-O --Mi→ g-9i: 3 6

Claims (1)

[Claims] In a magnetic storage device that records data of logical values rlJ and rOJ on a magnetic recording medium using a magnetic head and then reproduces the data, the recorded data read out by the magnetic head 7F is passed through a differentiating circuit and an integrating circuit, respectively. to form a differential waveform and an integral waveform, the differential waveform is sequentially passed through a first level slice circuit and a first delay circuit and converted into a peak pulse delayed by a predetermined number of hits, and the integral waveform is converted to a peak pulse delayed by a predetermined number of hits. After being converted into a peak pulse through a level slice circuit, it is further inputted in parallel to a second delay circuit and a monostable circuit, and the output of the monostable circuit and the peak pulse output delayed by a predetermined number of bits of the second delay circuit are used. Detecting the continuous position and time width of "0" in the recorded data, and using the detected time width signal as a gate signal to exclude pulses due to noise among the peak pulse group from the first delay circuit. 1. A reproducing method for a magnetic recording device 1a, characterized in that the magnetic recording device 1a extracts data by