JPH04301204A - Reproduction circuit for data recording/reproducing device - Google Patents

Abstract

PURPOSE:To always obtain a normal read data pulse by the reproducing operation of the servo information of different resolution and normal data in a data surface servo system. CONSTITUTION:A zero cross signal (c) is generated by differentiating the read- out signal (a) of a head 11, and detecting the zero cross point of this differential signal (b) by a comparator 15. Besides, at least, at the time of the reproduction of the normal data and the at the time of the reproduction of the servo information, a threshold signal S2 corresponding to each resolution is set. A shoulder omitted signal (d) is generated from this set threshold signal S2 by a shoulder omission circuit 17, and the read data pulse RD corresponding to the peak of the read-out signal (a) is generated on the basis of this shoulder omitted signal (d) and the zero cross signal (c).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reproducing circuit used in a data recording/reproducing apparatus such as a magnetic disk drive, and more particularly to a reproducing circuit having a shoulder cutout circuit in a data surface servo system.

0002

2. Description of the Related Art Conventionally, a magnetic disk drive uses a reproducing circuit that reads data recorded on a recording medium using a head and reproduces the read signal (analog signal) as a read data pulse, which is a digital signal. Generally, a reproducing circuit differentiates a read signal from a head and detects a zero-crossing point of the differentiated signal using a comparator, thereby reproducing a read data pulse corresponding to a peak point of the read signal.

By the way, in such a data reproducing operation, if the resolution is too high, the saddle portion of the differential waveform will cross zero, causing unnecessary pulses to be generated in the comparator output and erroneous pulses to be generated in the read data pulse. be. For this reason, conventional reproducing circuits are provided with a shoulder elimination circuit that full-wave rectifies the readout signal and converts the full-wave rectified waveform into a pulse signal at a predetermined threshold. I am trying to get a normal read data pulse with this removed.

0004

In recent years, with the demand for miniaturization, data surface servo systems such as sector servo systems have been increasingly adopted. The data surface servo method is a method in which servo information necessary for head positioning control is recorded on the data surface of a recording medium. In such a system, servo information and normal data, which have significantly different resolutions, must be handled by the same reproducing circuit. However, in conventional playback circuits, the shoulder output was fixed, so shoulder noise occurs when reproducing servo information with high resolution, and conversely, bits are likely to be missing when reproducing normal data with low resolution. was there.

The present invention has been made in view of the above points, and is a data plane servo system that can always obtain normal read data pulses by reproducing servo information with different resolutions and normal data. The purpose of the present invention is to provide a playback circuit for a recording/playback device.

[0006]

[Means for Solving the Problems] The present invention is a data recording/reproducing device using a data surface servo method, in which servo information necessary for head positioning control is recorded on the data surface of a recording medium, in which a head read signal is differentiated. Then, a zero-crossing signal is generated by detecting the zero-crossing point of the differential signal, and this is achieved by setting thresholds according to the respective resolutions at least when reproducing normal data and when reproducing servo information. A shoulder relief signal is generated using a set threshold value, and a read data pulse corresponding to the peak of the read signal of the head is generated based on the shoulder relief signal and the zero cross signal.

[0007]

[Operation] According to the above configuration, read data pulses can be generated with a shoulder cut signal depending on the resolution. Therefore, even in the data plane servo system where servo information with different resolutions and normal data must be handled by the same reproducing circuit, the optimum shoulder cutting signal can be set for each.
A normal read data pulse can always be obtained.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A reproducing circuit of a data recording/reproducing apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a reproducing circuit used, for example, in a data surface servo type magnetic disk device. In FIG. 1, a magnetic head 11 is connected to a recording medium 1.
It moves in the radial direction of 0 and records/reproduces data, and here it reads normal data or servo information recorded on the recording medium 10. Preamp (AMP)
) 12 amplifies the read signal (analog signal) of the magnetic head 11 and outputs it to a low pass filter (LPF) 13. The low-pass filter 13 is a circuit that removes high frequency noise from the read signal. The differentiating circuit 14 differentiates the read signal a from which noise has been removed by the low-pass filter 13 and outputs the differentiated signal b to the comparator 15 . The comparator 15 detects the zero-crossing point of the differential signal b and outputs the zero-crossing signal c to the pulse shaping circuit 18.

The threshold value setting circuit 16 sets a threshold value according to the resolution of normal data or servo information based on a control signal S1 from a controller (not shown), and outputs the threshold value signal S2 to the shoulder reduction circuit 17. The shoulder removal circuit 17 performs full-wave rectification on the readout signal a, converts the full-wave rectified waveform into a pulse signal using the threshold signal S2, and outputs the shoulder removal signal d to the pulse shaping circuit 18. The pulse shaping circuit 18 generates a read data pulse R corresponding to the peak of the read signal a based on the zero cross signal c from the comparator 15 and the shoulder removal signal d from the shoulder removal circuit 17.
Generate D.

FIG. 2 is a diagram showing the configuration of the threshold value setting circuit 16. In FIG. 2, the transistor 21 receives the control signal S
1, the resistor 22 is connected to the level shift circuit 24 when the resistor 22 is turned on. Level shift circuit 2
4 has a resistor 22 and a resistor 23, and shifts the level of the threshold signal S2 according to the resistance value thereof. Next, Figure 3
The operation of this embodiment will be explained with reference to the timing chart shown in FIG.

In response to the read signal from the magnetic head 11, a read signal a having an analog waveform as shown in FIG. 3 is output from the low-pass filter 13. The differentiating circuit 14 differentiates this read signal a and outputs a differentiated signal b. The comparator 15 outputs a zero-crossing signal c that is inverted at the zero-crossing point of the differential signal b. On the other hand, the shoulder removal circuit 17 outputs a shoulder removal signal d which is obtained by pulsing the readout signal a with the threshold signal S2. The pulse shaping circuit 18 outputs a read data pulse RD based on the shoulder reduction signal d and the zero cross signal c from the comparator 15.

[0013] Here, the normal data and servo information are as follows:
Each has different resolution. Generally, normal data has low resolution, and servo information has high resolution. If the resolution is too high, the saddle portion of the differential signal b will cross zero, as shown in Figure 3, and unnecessary pulses will be generated in the zero cross signal c.
An erroneous pulse may occur in the read data pulse RD. Therefore, when reproducing high-resolution servo information, an "L" level control signal S1 is sent from a controller (not shown).
is output. This control signal S1 turns off the transistor 21 in the threshold setting circuit 16 shown in FIG. 2, lowers the resistance value of the level shift circuit 24, and increases the level of the threshold signal S2 output from the level shift circuit 24. When the level of the threshold signal S2 increases, the pulse width of the shoulder removal signal d output from the shoulder removal circuit 17 becomes narrower, and the peak detection range becomes narrower. Thereby, erroneous pulses generated in the read data pulse RD can be reliably removed.

On the other hand, when reproducing normal data with low resolution, the "H" level control signal S1 is output, and the level of the threshold signal S2 is lowered. When the level of the threshold signal S2 decreases, the shoulder relief signal d output from the shoulder relief circuit 17
The pulse width of the signal becomes wider, and the peak detection range becomes wider. This makes it possible to prevent bit omission in the read data pulse RD.

In this way, the shoulder removal signal d according to the resolution is
The read data pulse RD can be generated. Therefore, even in the data side servo system where servo information with different resolutions and normal data must be handled by the same reproducing circuit, the optimal shoulder cutting signal d can be set for each to always produce a normal read data pulse. RD can be obtained.

[0016]

As described above, according to the present invention, a normal read data pulse with erroneous pulses reliably removed can be obtained when reproducing servo information with high resolution by setting a shoulder removal signal according to the resolution. Furthermore, when reproducing normal data with low resolution, a normal read data pulse without missing bits can be obtained. therefore,
In the data surface servo method, it is possible to improve the reproduction accuracy of read data pulses and always realize reliable data reproduction operation.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a reproducing circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing the configuration of a threshold value setting circuit of the same embodiment.

FIG. 3 is a timing chart for explaining the operation of the embodiment.

[Explanation of symbols]

10...Recording medium, 11...Magnetic head, 12...Preamplifier, 13...Low pass filter, 14...Differential circuit, 15...Comparator, 16...Threshold value setting circuit, 17...Shoulder removal circuit,
18...Pulse shaping circuit, 21...Transistor, 22,2
3...Resistor, 24...Level shift circuit, S1...Control signal, S2...Threshold signal, a...Read signal, b...Differential signal,
c...Zero cross signal, d...Shoulder release signal, RD...Read data pulse.

Claims (1)

[Claims] 1. A data recording and reproducing device using a data surface servo method in which servo information necessary for head positioning control is recorded on a data surface of a recording medium, comprising: a differentiating means for differentiating a read signal of the head; a zero-crossing detection means for detecting a zero-crossing point of a differential signal obtained by the means and generating the zero-crossing signal; and setting thresholds according to respective resolutions at least when reproducing the normal data and when reproducing the servo information. a threshold value setting means; a shoulder removal means for full-wave rectifying the read signal of the head and converting the full-wave rectified waveform into a pulse signal at the threshold value set by the threshold value setting means to generate a shoulder removal signal; The apparatus further comprises pulse shaping means for generating a read data pulse corresponding to the peak of the read signal of the head based on the shoulder removal signal of the shoulder removal means and the zero cross signal of the zero cross detection means. A reproducing circuit for a data recording/reproducing device.