Motion video signal processing for recording or reproducing – Local trick play processing – With randomly accessible medium
Reexamination Certificate
2000-03-17
2004-04-13
Chevalier, Robert (Department: 2715)
Motion video signal processing for recording or reproducing
Local trick play processing
With randomly accessible medium
C386S349000, C386S349000
Reexamination Certificate
active
06721494
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a data recording method and apparatus for recording digital data on a recording medium, such as a magnetic disc, and to a data reproducing method and apparatus for reproducing digital data from the recording medium.
2. Description of Prior Art
Recently, a hard disc drive, in which a magnetic disc, comprised of a metal substrate of e.g., aluminum, having its surface ground smooth, is used as a recording medium, and in which a floating slider, carrying a magnetic head, is floated over a data recording area of the magnetic disc to write or reproduce data, is in widespread use.
The hard disc drive has an extremely high data recording density and is able to store a large quantity of data. Moreover, data recorded thereon can be accessed at an extremely high speed. For this reason, the hard disc drive is widely used as a storage device for storing data processed by a computer.
FIG. 1
shows an illustrative structure of a signal processing circuit in the hard disc drive.
When digital data processed by a data processing device, such as a host computer, referred to below as recording data, is to be recorded on a magnetic disc by a hard disc drive
100
, shown in
FIG. 1
, a recording command first is routed from a data processing device, such as a host computer, to a central processing unit (CPU)
101
, whilst the recording data is routed to a host interface
103
in a hard disc controller
102
. The recording data, routed to the host interface
103
, is temporarily stored in a buffer memory
105
, under control by a bus controller
104
.
The CPU
101
instructs to a sequencer
106
in which sector on the magnetic disc the recording data is to be recorded, under a recording command routed from the data processing device, such as a host computer.
The magnetic head is positioned on the magnetic disc by a servo control circuit
107
computing the current magnetic head position, based on the position information detected by the magnetic head, and by the driving current of a voice coil motor (VCM) being controlled responsive to the current position of the magnetic head.
If the sequencer
106
has verified that the magnetic head is at the targeted position, it reads out recording data from the buffer memory
105
to route the recording data to an error correcting circuit (ECC)
108
. The recording data, routed to the ECC circuit
108
, is added to with an error correction code, and is subsequently transferred through a disc interface
109
to a channel IC
110
. The channel IC
110
channel-encodes the recording data, transferred thereto over a disc interface
109
, to convert the data to binary-valued signals. These signals are written by the magnetic head as magnetization inversion pattern. The operating timing of the disc interface
109
is controlled by the sequencer
106
.
If, when the recording data is recorded on the magnetic disc, the servo control circuit
107
detects that, due to an excessively large position signal from the magnetic head, it is difficult to continue the regular operation, the sequencer
106
transfers to a retry mode to perform the operation of re-recording the same sector. The information indicating the difficulty in continuing the regular operation may be routed from the servo control circuit
107
directly to the sequencer
106
or may be routed through the CPU
101
to the sequencer
106
.
For reproducing data recorded on the magnetic disc by the hard disc drive
100
, a playback command first is routed from a data processing device, such as a host computer, to the CPU
101
. The magnetic head then reads out the magnetization inversion pattern from the magnetic disc.
The magnetic head is positioned on the magnetic disc, by the servo control circuit
107
computing the current position of the magnetic head, based on the position information detected by the magnetic head, and by the VCM driving current being controlled responsive to the current position of the magnetic head.
The magnetization inversion pattern, read out for the magnetic disc by the magnetic head, is restored to digital data, referred to below as playback data, by the channel IC
110
performing the operations of waveform equalization, signal detection or channel code decoding. Although the playback data may be corrupted with errors, it is directly transferred to the disc interface
109
in-the hard disc controller
102
.
The operational timing of the disc interface
109
is controlled by the sequencer
106
. If the sequencer
106
has confirmed that the magnetic head is at a target position, the sequencer retrieves playback data from the channel IC
110
, over the disc interface
109
, to route the playback data to the ECC communication
108
.
The ECC circuit
108
decodes the error correction code appended to the playback data to execute error correction and detection. If an 8-symbol error correction code is appended to the playback data, the ECC circuit
108
is able to correct the error of the playback data up to the fourth symbol. However, if the number of symbols to be corrected is larger, the error correction is time-consuming thus lowering the processing speed. Therefore, in the above case, error correction up to the second symbol is made without exploiting the correction capability of the ECC circuit
108
to a maximum extent. If an error is found to be present in the as-corrected playback data, the sequencer
106
transfers to a retry mode to re-reproduce the same sector. In this case, the correction capability of the ECC circuit
108
is exploited to its maximum extent to correct the playback data for errors.
The hard disc drive is configured to execute decoding usually at a high speed and to raise the retry and correction capability only at the time of error occurrence to expedite the overall processing speed such as to maintain data reliability.
The playback data, processed by the ECC circuit
108
with error correction and detection, is temporarily stored in the buffer memory
105
, under control by the bus controller
104
. The playback data, stored in the buffer memory
105
, is sequentially transferred over the host interface
103
to a data processing device, such as a host computer.
Meanwhile, in keeping pace with the recent progress in the digital technique, digitized moving picture data is routinely processed on a computer. For providing means for storing moving picture data, thus processed on the computer, a demand has been raised for using a hard disc drive.
For recording and/or reproducing the moving picture data, a data stream making up the moving picture is desirably recorded and/or reproduced in real-time. Therefore, if the moving picture data is to be reproduced using the above-described hard disc drive
100
, it is necessary to sequentially transfer the playback data transiently stored in the buffer memory
105
from the buffer memory
105
to the data processing device, such as a host computer. The result is that, if an error is found to persist in the as-corrected playback data, and the retry operation is repeatedly performed until the error ceases to be detected, it may be an occurrence that the buffer memory
105
becomes void to stop the reproducing operation.
If, in order to evade this inconvenience, moving picture data is to be reproduced, using the hard disc drive
100
, the processing of directly transferring the playback data corrupted with errors to the data processing device, such as a host computer, is occasionally performed without performing the retry operation suffering from temporal indefinite elements. However, in such case, the reproduced moving picture data is deteriorated inevitably in picture quality.
On the other hand, if the moving picture data is recorded using the aforementioned hard disc drive
100
, recording data is sequentially transferred from the data processing device, such as a host computer, to the hard disc drive
100
, for storage in the buffer memory
105
. Thus, if a writing error is produced, but the retry operation is repeatedly performed until a w
Hayashi Nobuhiro
Kanno Hiroshi
Chevalier Robert
Kananen Ronald P.
Rader & Fishman & Grauer, PLLC
Sony Corporation
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