CA2120510C - Circuit for detecting unrecorded portion of recording medium - Google Patents
Circuit for detecting unrecorded portion of recording medium Download PDFInfo
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- CA2120510C CA2120510C CA002120510A CA2120510A CA2120510C CA 2120510 C CA2120510 C CA 2120510C CA 002120510 A CA002120510 A CA 002120510A CA 2120510 A CA2120510 A CA 2120510A CA 2120510 C CA2120510 C CA 2120510C
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- Canada
- Prior art keywords
- signal
- unrecorded portion
- recording medium
- window
- sync
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Classifications
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
- G11B27/19—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier
- G11B27/22—Means responsive to presence or absence of recorded information signals
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- Signal Processing For Digital Recording And Reproducing (AREA)
- Optical Recording Or Reproduction (AREA)
Abstract
Disclosed is a circuit for detecting an unrecorded portion in a recording medium, which comprises a window counting portion (10) for receiving an input signal to recognize if the input signal comes from an unrecorded portion of the recording medium and counting a predetermined time to generate a window pulse signal, and a sync signal generator (20) which is enabled by the window pulse signal, in which if the number of pulses of the input signal is not less than a predetermined number, the generator recognizes the current input signal comes from a data region of the recording medium to simultaneously generate a sync signal, while if the number of pulses of the input signal is not more than a predetermined number of pulses, the generator recognizes the current input signal comes from an unrecorded region of the recording medium, not to generate the sync signal. The unrecorded portion is accurately detected not to generate a sync signal due to noise included in the unrecorded portion of the recording medium.
Description
CIRCUIT FOR DETECTING UNRECORDED
PORTION OF RECORDING MEDIUM
TECHNICAL FIELD
The present invention relates to a magnetic storage device, and more particularly, to a circuit for detecting an unrecorded portion in a magnetic recording medium.
BACKGROUND ART
In general, a magnetic recording medium includes a sector identification code for distinguishing one sector from another. Also, there is an unrecorded portion between respective sectors. It should be noted that, since noise is generated in unrecorded portions of such a magnetic recording medium, a sync signal may not be generated at the exact starting point of a sector. That is, since the noise generated in an unrecorded portion may be mistaken for the starting point of a sector, the sync signal may be generated in the unrecorded portion.
FIG.IA represents the conventional data recording format of a hard disk.
In FIG. IA, a post-amble portion exists from an end location ENDS to a starting point of an unrecorded portion DC-GAP, sequentially followed by an unrecorded portion, a pre-amble portion and a data portion.
FIG. l B shows the location where a normal sync signal is generated in a conventional hard disk. Here, it can be seen that the normal sync signal is generated at a predetermined point of the pre-amble portion.
FIG.2 shows the location where a sync signal is generated in a conventional hard disk when one or two noise pulses included in the unrecorded portion are mistaken for a data signal. Thus, the conventional unrecorded portion detecting circuit of the recording medium erroneously generates a sync signal by recognizing as data pulses the noise pulses in the unrecorded portion of the recording medium.
DISCLOSURE OF THE INVENTION
Therefore, to solve the above problems, it is an object of the present invention to provide a circuit for detecting unrecorded portion in which, when unrecorded portion is detected, a starting point of a sector is accurately detected by ignoring noise pulses, thereby generating a desired sync signal.
To accomplish the above object of the present invention, there is provided a circuit for detecting unrecorded portion in a recording medium, comprising:
window counting means for receiving a signal to recognize that the signal comes from an unrecorded portion of the recording medium and for generating a window pulse signal by counting a predetermined time; and sync signal generating means which is enabled by the window pulse signal, in which if the number of pulses of the input signal is not less than a predetermined number, said sync signal generating means recognizes the current input signal comes from a data region of the recording medium to simultaneously generate a sync signal, while if the number of pulses of the input signal is not more than a predetermined number, said sync signal generating means recognizes the current input signal comes from an unrecorded region of the recording medium, not to thereby generate the sync signal.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings:
PORTION OF RECORDING MEDIUM
TECHNICAL FIELD
The present invention relates to a magnetic storage device, and more particularly, to a circuit for detecting an unrecorded portion in a magnetic recording medium.
BACKGROUND ART
In general, a magnetic recording medium includes a sector identification code for distinguishing one sector from another. Also, there is an unrecorded portion between respective sectors. It should be noted that, since noise is generated in unrecorded portions of such a magnetic recording medium, a sync signal may not be generated at the exact starting point of a sector. That is, since the noise generated in an unrecorded portion may be mistaken for the starting point of a sector, the sync signal may be generated in the unrecorded portion.
FIG.IA represents the conventional data recording format of a hard disk.
In FIG. IA, a post-amble portion exists from an end location ENDS to a starting point of an unrecorded portion DC-GAP, sequentially followed by an unrecorded portion, a pre-amble portion and a data portion.
FIG. l B shows the location where a normal sync signal is generated in a conventional hard disk. Here, it can be seen that the normal sync signal is generated at a predetermined point of the pre-amble portion.
FIG.2 shows the location where a sync signal is generated in a conventional hard disk when one or two noise pulses included in the unrecorded portion are mistaken for a data signal. Thus, the conventional unrecorded portion detecting circuit of the recording medium erroneously generates a sync signal by recognizing as data pulses the noise pulses in the unrecorded portion of the recording medium.
DISCLOSURE OF THE INVENTION
Therefore, to solve the above problems, it is an object of the present invention to provide a circuit for detecting unrecorded portion in which, when unrecorded portion is detected, a starting point of a sector is accurately detected by ignoring noise pulses, thereby generating a desired sync signal.
To accomplish the above object of the present invention, there is provided a circuit for detecting unrecorded portion in a recording medium, comprising:
window counting means for receiving a signal to recognize that the signal comes from an unrecorded portion of the recording medium and for generating a window pulse signal by counting a predetermined time; and sync signal generating means which is enabled by the window pulse signal, in which if the number of pulses of the input signal is not less than a predetermined number, said sync signal generating means recognizes the current input signal comes from a data region of the recording medium to simultaneously generate a sync signal, while if the number of pulses of the input signal is not more than a predetermined number, said sync signal generating means recognizes the current input signal comes from an unrecorded region of the recording medium, not to thereby generate the sync signal.
BRIEF DESCRIPTION OF THE DRAWINGS
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings:
3 ~12~~
FIG.1 A represents a conventional data recording format for a hard disk;
FIG.1B shows the location where a desired sync signal is generated in a conventional hard disk;
FIG.2 shows the location where a sync signal is generated in a conventional hard S disk when one or two noise pulses included in the unrecorded portion are mistaken for a data signal;
FIG.3 is a block diagram of one embodiment of an unrecorded portion detecting circuit according to the present invention; and FIG.4 is a timing diagram for explaining an operation of an unrecorded portion detecting circuit shown in FIG.3.
BEST MODE FOR CARRYING OUT THE INVENTION
The preferred embodiment of an unrecorded portion detecting circuit according to the present invention will be described below in more detail with reference to the accompanying drawings.
In FIG.3, an unrecorded portion detecting circuit according to the present invention comprises a window counting portion 10 for receiving read/write pulse signal and recognizing that the read/write signal comes from an unrecorded portion of a recording medium and generating a window signal by counting a predetermined time in response to a clock signal, and a sync signal generator 20 which is enabled by window counting means 10 for accurately generating a sync signal by determining if the number of pulses of the read/write signal is not less than a predetermined number of pulses.
Window counting portion 10 comprises unrecorded portion recognition device 100 for receiving the read/write signal and determining if the signal comes from the data region or the unrecorded region of the recording medium, a D-type flip-flop 200 which 2~~~.
FIG.1 A represents a conventional data recording format for a hard disk;
FIG.1B shows the location where a desired sync signal is generated in a conventional hard disk;
FIG.2 shows the location where a sync signal is generated in a conventional hard S disk when one or two noise pulses included in the unrecorded portion are mistaken for a data signal;
FIG.3 is a block diagram of one embodiment of an unrecorded portion detecting circuit according to the present invention; and FIG.4 is a timing diagram for explaining an operation of an unrecorded portion detecting circuit shown in FIG.3.
BEST MODE FOR CARRYING OUT THE INVENTION
The preferred embodiment of an unrecorded portion detecting circuit according to the present invention will be described below in more detail with reference to the accompanying drawings.
In FIG.3, an unrecorded portion detecting circuit according to the present invention comprises a window counting portion 10 for receiving read/write pulse signal and recognizing that the read/write signal comes from an unrecorded portion of a recording medium and generating a window signal by counting a predetermined time in response to a clock signal, and a sync signal generator 20 which is enabled by window counting means 10 for accurately generating a sync signal by determining if the number of pulses of the read/write signal is not less than a predetermined number of pulses.
Window counting portion 10 comprises unrecorded portion recognition device 100 for receiving the read/write signal and determining if the signal comes from the data region or the unrecorded region of the recording medium, a D-type flip-flop 200 which 2~~~.
has a data input terminal D for receiving the output of the unrecorded portion recognition device 100 and a clock terminal for receiving the read/write signal, and window forming device 300 which has a clear terminal CLR for receiving the output of D-type flip-flop 200 and a system clock terminal, wherein said window forming device 300 is enabled by the system clock and counts a predetermined time so as to form a window by performing a transition of a pulse state.
Sync signal generator 20 comprises a pulse counter/sync generator 400 having a clock terminal for receiving the read/write signal and a clear terminal cleared by the output of window forming device 300, thereby counting the number of pulses of the input signal to accordingly generate a sync signal, and an OR gate 500 for receiving the outputs of both unrecorded portion recognition device 100 and pulse counter/sync generator 400 to logically sum both the signals and to accordingly generate a sync signal.
FIG.4 is a timing diagram for explaining an operation of a preferred embodiment of the unrecorded portion detecting circuit shown in FIG.3.
In FIGs.3 and 4, if the number of input continuous pulses is less than or equal to two, it is assumed that the input pulses are noise. Unrecorded portion recognition means 100 receives data which has been read out from the magnetic recording medium and recognizes that the input signal comes from the unrecorded portion of the magnetic recording medium. D-type flip-flop 200 receives the output of unrecorded portion recognition device 100 and then if the input signal is received through the clock terminal, a pulse is generated. Window forming nleans 300 counts a predetermined time in responsive to the system clock and generates the window pulse signal, if the output of D-type flip-flop 200 is input to the clear terminal CLR. Here, the above predetermined time is a time during which three pulse signals can be input. As shown in Fig.4, window forming means 300 detects the rising edge of a first noise pulse of the input signal ...
s included in the unrecorded portion to generate a rising edge of a window signal, and then counts a predetermined time to generate a falling edge of the window signal.
Pulse counter/sync generator 400 generates a sync signal if the number of pulses of the signal input during an enabled period of the output of window forming device 300 is more than or equal to three, while pulse counter/sync generator 400 recognizes the input signal as noise so as not to generate the sync signal if the number of pulses of the signal input during the same period is less than or equal to two. That is, pulse counter/sync generator 400 detects a rising edge of the third pulse and generates a sync signal when it is determined that three pulses are input. Accordingly, logical summing device s00 outputs the sync signal only when the output of pulse counter/sync generator 400 is generated.
The generated sync signal is generated as being slightly delayed from the desired sync signal. Thus, it is necessary to add a sync signal correction circuit for synchronizing the desired sync signal with the sync signal appearing at the output side of logical summing device s00 shown in FIG.3. By doing so, correction of the sync signal is is simply performed.
The above-described embodiment has been explained under the assumption that if one or two pulses are input, the input pulses are noise. However, in other embodiments, both the window counting device and the sync signal generator may form a window signal with respect to the input signal more than or equal to a predetermined number of pulses, count the number of the input pulses and determine whether or not the input pulses are noise.
The above-described unrecorded portion detecting circuit according to the present invention counts the predetermined time to form the window pulse in window forming device 300, and generates the sync signal if not less Chall the predetermined number of pulses is input within the counted interval in pulse counter/sync generator 400 while if ~~~o~lo the predetermined number of pulses is not input, it is determined as noise so as not to finally generate the sync signal.
As descr~bed above, the unrecorded portion detecting circuit according to the present invention accurately detects the unrecorded portion not to generate a sync signal due to noise included in the unrecorded portion of the recording medium.
Accordingly, the present invention can improve reliability of electronic products requiring accurate synchronization.
INDUSTRIAL APPLICATION
The present invention can be widely applied in the field of the electronic household products in which signals are recorded and reproduced using recording media.
Sync signal generator 20 comprises a pulse counter/sync generator 400 having a clock terminal for receiving the read/write signal and a clear terminal cleared by the output of window forming device 300, thereby counting the number of pulses of the input signal to accordingly generate a sync signal, and an OR gate 500 for receiving the outputs of both unrecorded portion recognition device 100 and pulse counter/sync generator 400 to logically sum both the signals and to accordingly generate a sync signal.
FIG.4 is a timing diagram for explaining an operation of a preferred embodiment of the unrecorded portion detecting circuit shown in FIG.3.
In FIGs.3 and 4, if the number of input continuous pulses is less than or equal to two, it is assumed that the input pulses are noise. Unrecorded portion recognition means 100 receives data which has been read out from the magnetic recording medium and recognizes that the input signal comes from the unrecorded portion of the magnetic recording medium. D-type flip-flop 200 receives the output of unrecorded portion recognition device 100 and then if the input signal is received through the clock terminal, a pulse is generated. Window forming nleans 300 counts a predetermined time in responsive to the system clock and generates the window pulse signal, if the output of D-type flip-flop 200 is input to the clear terminal CLR. Here, the above predetermined time is a time during which three pulse signals can be input. As shown in Fig.4, window forming means 300 detects the rising edge of a first noise pulse of the input signal ...
s included in the unrecorded portion to generate a rising edge of a window signal, and then counts a predetermined time to generate a falling edge of the window signal.
Pulse counter/sync generator 400 generates a sync signal if the number of pulses of the signal input during an enabled period of the output of window forming device 300 is more than or equal to three, while pulse counter/sync generator 400 recognizes the input signal as noise so as not to generate the sync signal if the number of pulses of the signal input during the same period is less than or equal to two. That is, pulse counter/sync generator 400 detects a rising edge of the third pulse and generates a sync signal when it is determined that three pulses are input. Accordingly, logical summing device s00 outputs the sync signal only when the output of pulse counter/sync generator 400 is generated.
The generated sync signal is generated as being slightly delayed from the desired sync signal. Thus, it is necessary to add a sync signal correction circuit for synchronizing the desired sync signal with the sync signal appearing at the output side of logical summing device s00 shown in FIG.3. By doing so, correction of the sync signal is is simply performed.
The above-described embodiment has been explained under the assumption that if one or two pulses are input, the input pulses are noise. However, in other embodiments, both the window counting device and the sync signal generator may form a window signal with respect to the input signal more than or equal to a predetermined number of pulses, count the number of the input pulses and determine whether or not the input pulses are noise.
The above-described unrecorded portion detecting circuit according to the present invention counts the predetermined time to form the window pulse in window forming device 300, and generates the sync signal if not less Chall the predetermined number of pulses is input within the counted interval in pulse counter/sync generator 400 while if ~~~o~lo the predetermined number of pulses is not input, it is determined as noise so as not to finally generate the sync signal.
As descr~bed above, the unrecorded portion detecting circuit according to the present invention accurately detects the unrecorded portion not to generate a sync signal due to noise included in the unrecorded portion of the recording medium.
Accordingly, the present invention can improve reliability of electronic products requiring accurate synchronization.
INDUSTRIAL APPLICATION
The present invention can be widely applied in the field of the electronic household products in which signals are recorded and reproduced using recording media.
Claims (5)
1. A circuit for detecting an unrecorded portion in a recording medium, comprising:
window counting means for receiving a signal to recognize that the signal comes from an unrecorded portion of the recording medium and for generating a window pulse signal by counting a predetermined time; and sync signal generating means which is enabled by said window pulse signal, in which if the number of pulses of the input signal is not less than a predetermined number, said sync signal generating means recognizes the current input signal comes from a data region of the recording medium to simultaneously generate a sync signal, while if the number of pulses of the input signal is not more than a predetermined number, said sync signal generating means recognizes the current input signal comes from an unrecorded region of the recording medium, not to thereby generate the sync signal.
window counting means for receiving a signal to recognize that the signal comes from an unrecorded portion of the recording medium and for generating a window pulse signal by counting a predetermined time; and sync signal generating means which is enabled by said window pulse signal, in which if the number of pulses of the input signal is not less than a predetermined number, said sync signal generating means recognizes the current input signal comes from a data region of the recording medium to simultaneously generate a sync signal, while if the number of pulses of the input signal is not more than a predetermined number, said sync signal generating means recognizes the current input signal comes from an unrecorded region of the recording medium, not to thereby generate the sync signal.
2. The circuit for detecting an unrecorded portion in a recording medium according to claim 1, wherein said window counting means comprises unrecorded portion recognition means for receiving said input signal and recognizing that said input signal comes from the unrecorded portion of the recording medium, storage means for storing the output of said unrecorded portion recognition means and generating the output of said unrecorded portion recognition means in response to said input signal, window forming means which is enabled by the output of said storage means and for counting a predetermined time in response to a predetermined clock to form a window signal.
3. The circuit for detecting an unrecorded portion in a recording medium according to claim 2, wherein said sync signal generating means comprises a pulse counter/sync generator which is enabled in response to the output of said window forming means and for receiving said input signal to then generate a certain pulse signal if a predetermined number of pulses are input, and on the other hand not to then generate said certain pulse signal if the predetermined number of pulses are not input, and means for logical summing of the outputs of both said unrecorded portion recognition means and the pulse counter/sync generator to output the sync signal.
4. The circuit for detecting an unrecorded portion in a recording medium according to claim 1, wherein said unrecorded portion detection circuit further comprises sync signal corrector means for receiving the output of said sync signal generating means and for generating an accurate sync signal.
5. The circuit for detecting an unrecorded portion in a recording medium according to claim 2, wherein said window forming means detects the rising edge of the first noise pulses included in said unrecorded portion to then generate the rising edge of a window signal, and counts a predetermined time to then generate the falling edge of the window signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002120510A CA2120510C (en) | 1992-11-30 | 1992-11-30 | Circuit for detecting unrecorded portion of recording medium |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/KR1992/000070 WO1994012982A1 (en) | 1992-11-30 | 1992-11-30 | Circuit for detecting unrecorded portion of recording medium |
| CA002120510A CA2120510C (en) | 1992-11-30 | 1992-11-30 | Circuit for detecting unrecorded portion of recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2120510A1 CA2120510A1 (en) | 1994-05-31 |
| CA2120510C true CA2120510C (en) | 2001-05-01 |
Family
ID=34796017
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002120510A Expired - Fee Related CA2120510C (en) | 1992-11-30 | 1992-11-30 | Circuit for detecting unrecorded portion of recording medium |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2120510C (en) |
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1992
- 1992-11-30 CA CA002120510A patent/CA2120510C/en not_active Expired - Fee Related
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| Publication number | Publication date |
|---|---|
| CA2120510A1 (en) | 1994-05-31 |
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