JP3200466B2 - Magnetic recording / reproducing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording / reproducing circuit for a magnetic disk drive using an embedded sector servo system.

[0002]

2. Description of the Related Art A magnetic disk drive of the embedded sector servo system uses a magnetic disk for recording and reproducing data on the basis of positioning information previously recorded radially with respect to a disk circle at the head of each data sector. The information to be reproduced by rotating the disk is to output the servo area containing the positioning information and the data area containing the original recording data information alternately. .

As shown in FIG. 3, a recording / reproducing circuit (11) of a conventional magnetic disk drive using an embedded sector servo system includes a recording / reproducing magnetic head (22) for recording / reproducing magnetic data on a disk surface, and a magnetic recording / reproducing head (22). A recording / reproducing amplifier (24) for making the recording state and reproducing state electrically function with respect to the head, an AGC amplifier (26) for making the reproducing signal in the reproducing state a uniform amplitude, and a digital voltage for outputting the output signal of the AGC amplifier. A pulsing circuit system (28) for converting into a pulse, and a servo pattern identification for identifying a servo area and a data area on a track of a disk based on a pulsed reproduction signal and extracting positioning information from the servo area. It is composed of a circuit (32).

FIG. 4 shows an operation up to an AGC amplifier waveform output (RDB) when data is recorded in a data area on a disk track in these conventional recording / reproducing circuits. Since it is necessary to perform positioning control even during recording, only the data area must be recorded, and the information in the servo area immediately after that must be normally reproduced, and the magnetic head and the recording / reproducing amplifier are switched to the reproducing state and the recording state. The gate signal (WG) operates so as to record only the data area while avoiding the servo area. At this time, the AG which turns on / off the AGC function of the AGC amplifier
The C gain hold signal (GH) normally turns on the AGC function for gain correction at the beginning of the data area and the servo area regardless of recording or reproduction, and AGC gain hold only the positioning information portion of the servo area. State (AGC function OFF state) to operate so as to accurately extract positioning information in the servo area and reduce reproduction errors in the data area.

[0005]

However, according to the above-mentioned conventional method, when the magnetic head switches from the recording state to the reproducing state, the recording / reproducing amplifier output waveform (RDA) is obtained.
Immediately after switching from the recording state to the reproduction state on the AGC output waveform (RDB) because the AGC function of the AGC amplifier tries to follow the voltage amplitude of the spike noise in FIG. An unstable output area as shown occurs, and the recording / reproduction recovery time becomes longer.

Therefore, an extra buffer area must be provided in the servo area to avoid the time of the output unstable area. However, when the servo area is shortened and the data area is relatively widened for the purpose of increasing the capacity of the magnetic disk device, there is a problem that the buffer area becomes an obstacle.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording / reproducing circuit in which an AGC output waveform is not disturbed immediately after switching from a recording state to a reproduction state, with the object of realizing a recording / reproduction recovery time capable of increasing the capacity of a magnetic disk drive. It is an object.

[0008]

In order to achieve the above object, the present invention provides a write gate signal for switching between a recording state and a reproduction state and an AGC gain hold signal, which are used before and after a spike-like noise is generated. A recording / reproducing circuit having a configuration in which a new AGC fixing circuit for turning off the AGC function of the AGC amplifier is added enables provision of a high-capacity magnetic recording / reproducing apparatus.

[0009]

When the AGC function is OFF (gain hold state), the gain of the AGC amplifier is held at the gain immediately before the AGC function is turned OFF, and becomes a fixed gain. In this state, even if spike noise is input to the AGC amplifier, the output waveform is not disturbed. Therefore, by turning off the AGC function immediately before and after the spike noise, the AGC function is immediately turned on again.
The recording / reproduction recovery time can be greatly reduced.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a recording / reproducing circuit according to the present invention. An apparatus according to the present invention comprises a recording / reproducing magnetic head (2) for recording / reproducing magnetic data on / from a disk surface, a recording / reproducing amplifier (4) for electrically operating the recording / reproducing state of the magnetic head, An AGC amplifier (6) for making the reproduced signal in the state uniform in amplitude, a pulsing circuit system (8) for converting the output signal of the AGC amplifier into a digital voltage pulse, and a disk based on the pulsed reproduced signal. And a servo pattern identification circuit (12) for identifying a servo area and a data area on the track and extracting positioning information from the servo area, and further generated from the servo pattern identification circuit (12). An AGC gain hold signal (GH) and a write gate signal (WG) for switching between recording and reproduction are taken in, and before and after switching from the recording state to the reproduction state. During a magnetic recording and reproducing apparatus having a reproducing circuit constructed by adding a logic signal (GH') gain hold gate circuit for generating the (14) to OFF the AGC function (1).

FIG. 2 shows a recording / reproducing circuit according to the present invention.
This shows the operation up to the AGC amplifier waveform output (RDB ') when recording data in the data area on the disk track. The write gate signal (WG) for switching the magnetic head (2) and the recording / reproducing amplifier (4) between the reproducing state and the recording state operates so as to record only the data area, avoiding the servo area. At this time, the gain hold gate circuit (14) recognizes the falling edge of the write gate signal (WG), that is, the switching from the reproduction state to the recording state, and counts an internal timer. When switching from the recording state to the reproducing state again, spike noise occurs in the recording / reproducing amplifier output waveform (RDA), but the timing of switching from the recording state to the reproducing state can be predicted from the time length of one sector.

The gain hold gate circuit (14) keeps counting the internal timer until the time when spike noise is predicted to occur, and newly adds the AGC amplifier (6) to the gain hold gate circuit before and after the noise occurrence. Is switched to the AGC function OFF state (gain hold state) by the logic signal (GH ′) generated by the above.

At this time, spike noise is input to the AGC amplifier (6). However, since the AGC function is OFF, the gain is held at a fixed gain, and the output waveform of the AGC amplifier follows the voltage amplitude of the spike noise. (RDB ')
The phenomenon of instability does not occur.

When the noise generation period has passed,
The AGC function is returned to ON, and the gain is corrected to accurately capture the positioning information in the servo area as in the operation of the conventional recording / reproducing circuit. The gain is held, and the AGC function of the AGC amplifier (6) is turned on as soon as the servo area enters the data area.

When the recording operation is not performed and the reproduction state continues over several sectors, no spike noise is generated and the write gate signal (WG) input to the gay hold gate circuit (14) is active. Not be
The timer inside the gain hold gate circuit does not start, the AGC function is turned on at the beginning of the data area and the servo area, and the AGC function is turned off only when the positioning information is taken in.

[0016]

When switching from the recording state to the reproducing state,
The phenomenon that the AGC amplifier was disturbed by spike noise generated from the recording / reproducing magnetic head was eliminated, and the recording / reproducing recovery time could be reduced to about 50% of the conventional one. As a result, the servo area on the disk can be shortened, and the capacity of the disk device can be increased.

Further, in the case of a magnetic recording / reproducing apparatus which does not require a particularly high capacity, the reliability of data reproduction and the accuracy of head positioning can be remarkably improved by eliminating the disorder of the AGC amplifier. did it.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an embodiment of the present invention, and is an operation chart.

FIG. 3 is a drawing showing a conventional technique, and is a circuit configuration diagram.

FIG. 4 is an operation chart diagram showing a conventional technique.

[Explanation of symbols]

 2, 22 Recording / reproducing magnetic head 4, 24 Recording / reproducing amplifier 6, 26 AGC amplifier 8, 28 Pulsing circuit system 10, 30 ENDEC / HDC system 12, 32 Servo pattern identification circuit 16, 34 Servo circuit system 14 Gain hold gate circuit

Claims (1)

(57) [Claims] 1. A recording / reproducing magnetic head and a recording / reproducing magnetic head.
Uniform reproduction signal from the magnetic disk and the recording and reproducing magnetic head having a servo information recorded positioning information de
Signal reproduction circuit with AGC amplifier
And the recording / reproducing magnetic head stores information on the magnetic disk.
The AGC function of the AGC amplifier is
In the magnetic recording and reproducing apparatus in the ON state, the signal reproduction circuit is switched from the recording state to reproducing state immediately before
Release the AGC function ON state in the AGC amplifier
And fix the output gain, and in the servo area
Once turn on the AGC function of the AGC amplifier, then
To turn off the AGC function of the AGC amplifier again.
And a magnetic recording / reproducing apparatus.