Dynamic information storage or retrieval – Control of storage or retrieval operation by a control... – By medium defect indicative control signal
Reexamination Certificate
2000-02-03
2002-01-22
Young, W. R. (Department: 2652)
Dynamic information storage or retrieval
Control of storage or retrieval operation by a control...
By medium defect indicative control signal
C369S053170
Reexamination Certificate
active
06341109
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for replacing defective areas and to an information writing/reading device having the functions for executing replacement, and particularly to a defective area replacement method and information writing/reading device capable of maintaining both the transfer rate and reliability of data.
2. Description of the Related Art
An information writing/reading device of the prior art is first described with reference to the accompanying figures. Recording medium
9
shown in
FIG. 1
is, for example, an optical disk medium with tracks that are cut in accordance with spiral or concentric guide grooves, the writing marks of the tracks being formed according to the intensity of a condensed laser beam that is irradiated upon the recording medium by head
8
. As shown in
FIG. 2
, the tracks formed on recording medium
9
are in turn formed from header portions in which physical address data are written at fixed intervals to indicate locations on tracks, and data portions used for writing data. A sector is constituted by an area made up by a header portion paired with a data portion. Physical addresses are assigned without duplication to all sectors on a track.
Sectors on the recording medium are further divided into a plurality of areas by physical addresses.
FIG. 3
is a schematic view showing one example of the format of a recording medium. A lead-in area made up of a plurality of sectors is provided at the start of a track, and a lead-out area made up of a plurality of sectors is also provided at the end of a track. The lead-in area. and lead-out area are not used for writing and reading data, and only physical addresses are written in these areas. Detection of these physical addresses allows determination of whether the relevant area is not to be subject to writing/reading. Defect management areas are provided in two locations: just inside the lead-in area and lead-out areas. A plurality of user areas and spare areas are provided inside these two areas. Spare areas are provided at the end of zones that are partitioned according to, for example, the number of sectors contained in one rotation of the disk, and the proportion of spare areas is approximately 0.5% that of the user areas.
Information relating to defective sectors in the user areas and spare areas is recorded in defect management areas, defect management areas being provided in at least two locations. In this way, despite the occurrence of a defective sector in the sectors of one defect managing area, the other defect management area can provide back-up so that information relating to defective sectors in the user areas and spare areas is not lost. Recording identical information in a plurality of areas allows use of defect management information as long as reading of any set of information is successful.
The information written in a defect management area is made up by a slip replacement list and a linear replacement list. Defective sectors are indicated using the type of format shown in
FIG. 4
, which shows one example of the write format in a defect management list.
The physical addresses of defective sectors that were extracted in the certification process are written in the slip replacement management list shown in this figure. In order from the beginning, the list includes: a slip replacement list identification number, which indicates that the content of the list is a slip replacement list; the number of slip replacement defects registered in the list; and the physical addresses of defective sectors. A buffer area is provided at the end of the slip replacement list so that the length of the list can be kept uniform regardless of the number of defects registered.
The linear replacement list is written after the slip replacement list. The linear replacement list is used for replacement of sectors having secondary defects not detected during certification. In order from the beginning, the list includes: a linear replacement list identification number indicating that the content of the list is a linear replacement list; the number of list updates; and the number of linear replacement defects registered in the list, following which a number of replacement origin physical addresses, each paired with a replacement destination physical address, are written, the number of these pairs being equal to the number of registered defects. Finally, the number of list updates is again recorded at the end. The linear replacement list portion of the data recorded in the defect management area can be rewritten. The number of updates is recorded in two locations, i.e, close to the beginning and at the end of the linear replacement list, to allow verification that the list has been correctly updated. A discrepancy between these two numbers allows determination of the possibility of an interruption in writing when the list was updated.
Returning now to
FIG. 1
, the flow of processes in an information writing/reading device is next explained. At the time of starting up information writing/reading device
10
, CPU
1
instructs head position control circuit
6
to read the defect management areas of recording medium
9
. Head
8
moves to a defect management area under the control of head position control circuit
6
and outputs the read signals. The read signals output from head
8
are sent as data of the defect management area to disk control circuit
4
by way of write/read signal processing circuit
7
and format control circuit
3
. Disk control circuit
4
stores the data of the defect management area in buffer memory
5
. The data of the defect management area that is temporarily stored in buffer memory
5
is further read from buffer memory
5
by disk control circuit
4
and transferred to the slip replacement list storage section and linear replacement list storage section of memory
2
.
The replacement of defective areas in the write/read operations of recording medium
9
is executed based on the information that is in the slip replacement list storage section and linear replacement list storage section in memory
2
.
A write request from host device
11
is sent to disk control circuit
4
along with logical addresses indicating the write locations. Disk control circuit
4
reports to CPU
1
that a write request from host device
11
has been generated. CPU
1
receives the content of the request from disk control circuit
4
and instructs disk control circuit
4
to transfer data from host device
11
to buffer memory
5
. The data to be written are thus taken from host device
11
by disk control circuit
4
and temporarily stored in buffer memory
5
.
In CPU
1
, the physical addresses on recording medium
9
are calculated from the logical addresses of the data to be written, and a write request of the data that are to be written to the calculated physical addresses is sent to head position control circuit
6
and format control circuit
3
.
FIG. 5
is a block diagram that focuses on, of the functions of CPU
1
, memory
2
, and format control circuit
3
in information writing/reading device
10
, the functions that are related to replacement processing and address conversion processing.
In
FIG. 5
, address converting means
103
provided in CPU
1
is equipped with functions for calculating the physical addresses of recording medium
9
that correspond to the logical addresses of the data to be written using the information of slip replacement list storage section
202
and linear replacement list storage section
203
that are provided in memory
2
.
Head
8
moves in the direction of the physical addresses of recording medium
9
based on the control of head position control circuit
6
and in addition, outputs address signals read from recording medium
9
. The address signals are sent to format control circuit
3
by way of write/read signal processing circuit
7
. Upon detecting the physical addresses designated by CPU
1
, format control circuit
3
receives the data to be written from buffer memory
5
by way of disk c
NEC Corporation
Nguyen Dzung C.
Young W. R.
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