JPS58133615A - Data reader - Google Patents

Abstract

PURPOSE:To recognize the marginal rate of generation of readout errors at an arbitrary recording position, by suitably changing the amount of phase difference to be changed relatively with the instruction of the upper-order device or a maintenance device. CONSTITUTION:A peak point detection circuit 14 inputs a reading signal 101 and outputs a peak sense signal 102. A discriminating signal generation circuit 15 outputs a window signal 103 taking a minimum pulse interval of pulses b1-b5 as a period. A reading data signal 104 is outputted from an AND circuit 16. In the state as indicated above, when an instruction signal 107 or 108 is given from the upper-order device 21 or the maintenance device 22 to a phase difference set circuit 17, the circuit 17 outputs a marginal mode signal 105 to the circuit 15, which changes the phase of the data window of the signal 103 relatively to the pulse of a peak sense signal 102.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data reading device, and more particularly to a data reading device having a rounding discrimination signal generating circuit for demodulating magnetically recorded nine information.

In general, one of the important problems in data reading devices for magnetically recorded information is the quality of read data, that is, the read error (hereinafter referred to as read error) K that occurs when reading recorded information. There are various factors that cause read errors, but in general, read errors tend to occur more easily as recording devices become more sophisticated.Therefore, as the recording density increases, magnetic storage devices become more prone to read errors. This has become a serious issue.

Among the means for dealing with read errors, one of the commonly used means is that when a series of errors occur, the read error occurs and the nine locations are read again. Another way to obtain information is to know in advance the location of the recording medium where repeated errors are likely to occur, for example, and to take measures to avoid this. The purpose is to prevent errors from occurring.

In the latter method, it is necessary to reliably detect in advance the margin against the occurrence of a read error. Conventionally, as a means for this purpose, a read signal (having an analog signal) successively output by a magnetic head is used. A consideration detection signal (hereinafter referred to as a peak sense signal) having a square pulse corresponding to a peak sense pulse (hereinafter referred to as a peak sense pulse), and a square pulse whose period is the minimum interval between the peak sense pulses. When demodulating the read signal by comparing it with a discrimination signal (hereinafter referred to as a window signal) consisting of
Means is used to change the error rate of read data by changing the relative phase relationship between the peak sense signal and the window signal, thereby detecting the margin rate of read error occurrence.

However, with the above-described means of changing the relative phase relationship between the wind signal and the peak sense signal,
To uniformly change the relative phase relationship to all information recorded on the recording medium.

There are cases where it is impossible to detect the probability of occurrence of a read error at a specific recording position.

In other words, 1. For example, in the case of recording in the recording format as shown in FIG. gives the same change in relative phase relationship as data section 2, so if a read error occurs in header section l, it will not be possible to start the read operation to data section 2. It becomes impossible to know the margin of occurrence.

The object of the invention is therefore to obviate the above-mentioned drawbacks.

It is desirable to provide a data reading device that can determine the probability of occurrence of a read error at any desired recording position.

The data reading device of the present invention includes a peak point detection circuit which inputs a read signal read by a magnetic head and outputs a peak/point detection signal, and a discrimination circuit which inputs the read signal and outputs a discrimination signal. a signal generation circuit, a phase difference setting signal for outputting a phase difference setting signal to the discrimination signal generation circuit in response to a command from the host device or the maintenance device, and a phase difference setting position in response to the command from the host device or the maintenance device. a phase difference setting position selection signal that outputs a selection signal to the discrimination signal generation circuit;
The device is configured to include a predisposition consideration detection signal, the discrimination signal, and an AND circuit which receives the input signal and outputs a read data signal.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

ζ FIG. 2 shows an embodiment in which the present invention is applied to a magnetic disk device. In FIG. 2, the information signal sequentially output from the magnetic field 11 is amplified by the first stage amplifier circuit 12 and the second stage circuit 13 and is inputted as a read signal 101 to the peak point detection circuit 14 and the discrimination signal generation circuit 15.

The peak point detection circuit 14 inputs the read signal 101 and generates a peak sense detection signal (peak sense pulse) having a rectangular pulse (peak sense pulse) corresponding to the peak point of the read signal 101 and synchronized with the peak point. The signal) 102 is output to the AND circuit 16. 9. Discrimination signal generation circuit 15
Inputs the read signal 101 and calculates the minimum interval between the helical end points of the read signal 101. Discrimination signal (wind signal) 1 consisting of a rectangular pulse whose period is the minimum interval of Yx-/<vxQ and whose width is wider than the width of the peak sense pulse.
03 to the AND circuit 16, and the AND circuit 16 outputs the peak sense signal 102 and the window signal 103. The read data signal 104 is output by performing a logical product with the .

On the other hand, the phase difference setting circuit 17 inputs a command signal 107 or 108 from the host device 21 and maintenance device 22, and outputs a peak sense signal 102 to the discrimination signal generation circuit 15.
Then, a phase difference setting signal (hereinafter referred to as a marginal mode signal) 105 that gives a command to change the relative phase of the window signal 103 is output.

The gate 1 phase difference setting position selection circuit 18 inputs the command signal 109 or 110 from the host device 21 and the maintenance device 22, and outputs a phase difference setting position selection signal (hereinafter referred to as gate 1) to the discrimination signal generation port 15. 106 (referred to as a leading input signal). This gate ting signal 106 is
This signal instructs at what position in the recording format on the magnetic disk the relative phase difference between the peak sense signal 102 and the wind signal 103, which is commanded by the normal mode signal 105, is to be set.

(Recording format refers to a physical recording unit of a collection of information when recording information on a magnetic disk.) Next, we will explain the operation of the embodiment of FIG. 2 configured as described above. This will be explained with reference to the waveform diagram in FIG.

The data pattern l11 as shown in FIG.
It is assumed that the write signal 112 is recorded using the ψ key method. (The MFM inflection method is a modulation method for magnetic recording that not only inverts the write current with information a11 but also inverts the bits when two or more '01's occur in succession.) The above recording information As shown in Figure 2, the magnetic
1, the first stage amplifier circuit 12 and the readout circuit 13
The signal is amplified by 101 and sent to the peak/point detection circuit 14 as a read signal 101, but the waveform at this time is an analog 4G waveform having ``1 + ''tease 14 and Hatake 1 as shown in FIG. be.

The sense detection circuit 14 inputs the read signal 101 and generates peak sense pulses bt, bI, bs corresponding to the sense "l+"ls"ls"4 and a.
, ba and bI.
Outputs 2.

On the other hand, the read signal 101 is also input to the discrimination signal generation circuit 15, and is output at the minimum pulse interval among the pulse intervals of the peak sense pulses b1 to b.

~b, and data window c1 +'t m 'le '4 m whose period is the same interval as b4~b1
A window signal 103 having l, c, and t is output.

The above-mentioned peak sense signal 102 and win read/loss data signal 104 are output.

In the above state, in order to detect the read error margin rate, when the command signal 107t or 108 is sent from the host device 21t and the maintenance device 22 to the phase difference setting circuit 17, the 1 phase difference setting circuit 17 outputs a discrimination signal. A marginal mode signal 105 is sent to the generation circuit 15, and the discrimination signal generation circuit 15 changes the phase of the data window of the window signal 103 from the peak to the peak of the sense signal 102 according to the command of the marginal mode signal 105. - Change relative to the sense pulse. Wind signal 103' and window signal 103'' in FIG. 3 are examples of cases in which the phase of the data window is delayed and advanced relative to the peak sense pulse, respectively.

In this way, by appropriately changing the amount of phase difference to be relatively changed in accordance with commands from the host device or maintenance device, it is possible to detect the desired reading error margin rate. If the data is recorded using the recording format shown in Figure 1, even though we want to know the read error margin rate in the data part 2, an error occurs in the data part l, so we cannot read the data into the data part 2. Since no operation is performed, it may not be possible to detect the read error margin rate of the ninth data section 2.

At this time, the command signal 109 or 110 is sent from the host device 21 or the maintenance device 22 to the phase difference setting position selection circuit 18.
91 The phase difference setting position selection circuit 18 sends the shift timing signal 106 to the discrimination signal generation circuit 15 to change the relative phase of the data window with respect to the peak sense pulse only for the data section 2. command to do so.

As a result, the phase with respect to the peak sense pulse of the data window can be changed only for the data section 2 without changing the phase for the data section 1, which prevents the occurrence of read errors in the data section 2. The margin rate can be detected.

The above-mentioned relative phase change + position specification within the lid is not limited to the data section only, but can be applied to the p-data voice section or the p-data voice section by specifying the start and end bit positions of the desired position. , any part of the da part can be specified.

In addition, if a series of errors occur due to misalignment of the waveform of the read data, when retrying the read, a window signal is sent to the location where the read error occurred based on instructions from the host device. A successful read retry can also be achieved by providing a change in relative phase.

As explained in detail above, by using the data reading device of the present invention, it is possible to detect the margin rate of occurrence of read errors at any recording position of the magnetic recording device. This has the effect of increasing the success rate of read retries against successive errors caused by misalignment.

[Brief explanation of the drawing]

FIG. 1 is a recording format diagram showing an example of a recording format on a magnetic disk, FIG. 2 is a professional diagram of an embodiment of the present invention, and FIG.
The figure is a waveform diagram of the main part of FIG. 2. In the figure, l...header section, 2...
Data section, 3...Sector, 11...Magnetic, De, 12...First stage amplifier circuit, 13...
. . . Readout circuit, 14 . . . Peak value detection circuit,
1.1...Discrimination signal generation circuit, 16...
AND circuit, lf... phase difference setting circuit, 18.
...Phase difference setting position selection circuit, 21...
Upper device. 22... Maintenance device. Figure 1 Figure 2 Data, pattern jll I I
OOl 141 Betsu-i Official Number 103' Discrimination I-Kichi Number 1 (13” Fig. 3

Claims (1)

[Scope of Claims] A peak point detection circuit that inputs a read signal read by a magnetic head and outputs a peak point detection signal. and a discrimination signal generation circuit that receives the read signal and outputs a discrimination signal. a phase difference setting circuit that outputs a phase difference setting signal to the discrimination signal generation circuit in response to a command from a host device or a maintenance device; A data reading device comprising: a phase difference setting position selection circuit that outputs to a signal generation circuit; and an AND circuit that receives the peak point detection signal and the discrimination signal as input and outputs a read data signal.