GB2343569A - Optical disk player - Google Patents
Optical disk player Download PDFInfo
- Publication number
- GB2343569A GB2343569A GB0000163A GB0000163A GB2343569A GB 2343569 A GB2343569 A GB 2343569A GB 0000163 A GB0000163 A GB 0000163A GB 0000163 A GB0000163 A GB 0000163A GB 2343569 A GB2343569 A GB 2343569A
- Authority
- GB
- United Kingdom
- Prior art keywords
- sync
- signal
- output
- optical disk
- playback clock
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/10—Digital recording or reproducing
- G11B20/14—Digital recording or reproducing using self-clocking codes
- G11B20/1403—Digital recording or reproducing using self-clocking codes characterised by the use of two levels
-
- 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
- G11B27/28—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording
- G11B27/30—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on the same track as the main recording
- G11B27/3027—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on the same track as the main recording used signal is digitally coded
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B2220/00—Record carriers by type
- G11B2220/20—Disc-shaped record carriers
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Signal Processing For Digital Recording And Reproducing (AREA)
Abstract
An optical disk player comprises an optical disk, a pickup 202 for reading data recorded on the disk, an amplifier 204 for amplifying the pickup output, a binarizer 206 for binarizing the amplifier output, a voltage controlled oscillator (VCO) 208 for generating a playback clock, a sync detection device 210 for receiving the playback clock and an output of the binarizer to detect a sync signal therefrom, a phase detector 212 for receiving the playback clock and the binarizer output to detect a phase difference therebetween, a lowpass filter 214 for lowpass filtering an output of the phase detector, an average value calculator 216 for calculating an average value for an output of the lowpass filter when a defect is detected, and a switching circuit 218 for providing the VCO 208 with an output of the lowpass filter when the defect is not detected, and providing the VCO 208 with an output of the average value calculator when the defect is detected.
Description
SYNC DETECTION DEVICE AND OPTICAL DISK PLAYER
HAVING THE SAME
The present invention relates to an optical disk player, and in particular, to a sync detection device for detecting a sync signal from a signal read from an optical disk.
An optical disk player includes a sync detection and protection device for detecting a sync signal and protecting the detected sync signal, in order to minimize damage to the data read out from an optical disk.
A conventional optical disk player is schematically illustrated in Figure 1. In the drawing, a pickup 102 reads data recorded on an optical disk 100, generates an RF (Radio Frequency) signal according thereto, and provides an RF amplifier 104 with the RF signal. The RF amplifier 104 amplifies the RF signal and provides it to a binarizer 106. The binarizer 106 binarizes the output of the RF amplifier to generate binary data SDATA in series to a sync detection and protection device 110. The sync detection and protection device 110 receives the binary data SDATA and a playback clock PLCK generated from a voltage controlled oscillator (VCO) 108 to detect a sync signal therefrom, and protects the detected sync signal; in case the sync signal is not detected successfully, the sync detection and protection device 110 inserts a sync signal (i. e., generates a sync insertion signal).
Further, the playback clock PLCK and the binary data
SDATA are applied to a phase detector 112. The phase detector 112 compares a phase of the playback clock PLCK with a phase of the binary data SDATA to detect a phase difference therebetween, and the comparison results are fed back to the VCO 108 via a lowpass filter 114. When a defect is detected, the lowpass filter 114 holds its output value. The VCO 108 generates the playback clock
PLCK according to the output of the lowpass filter 14, in synchronism with the data read from the disk 100.
Referring to Figure 2, the sync detection and protection device 110 includes a sync detector 116 and a sync insertion and protection device 124. The sync detector 116 consists of a register 118, a sync pattern decoder 120, and a sync generator 122. The register 118, consisting of a serial-input-parallel-output register, loads the binary data SDATA in series according to the playback clock PLCK, and provides the loaded binary data
SDATA in parallel to the sync pattern decoder 120. The sync pattern decoder 120 checks whether the binary data
SDATA provided in parallel from the register 118 is coincident with the sync pattern, to generate a sync detection signal to the sync generator 122 if the binary data SDATA is coincident with the sync pattern.
The sync insertion and protection device 124 counts the playback clock PLCK, and generates a sync protection window signal to the sync generator 122 when the count value corresponds to a position where the sync signal is to be generated. The sync detector 122 checks whether the sync detection signal is generated during generation of the sync protection window signal, to output the sync detection signal as the sync signal if the sync detection signal is generated during generation of the sync protection window signal. However, if the sync detection signal is not generated during generation of the sync protection window signal, the sync generator 122 requests the sync insertion and protection device 124 to generate the sync insertion signal, and outputs the sync insertion signal as the sync signal. The number of the sync insertion signals is determined previously. After outputting the predetermined number of sync insertion signals, the sync generator 122 resets the sync insertion and protection device 124.
As described above, after the sync protection window signal is out of sync with the sync detection signal, even though the sync detection signal is generated normally, the predetermined number of the insertion sync signals will be generated unconditionally unnecessarily.
Further, after generation of the sync insertion signals, the sync protection window is reset according to the sync detection signal; at this moment, sync noises may be generated unexpectedly. In this case, the sync protection window is erroneously set, and accordingly, the normal sync detection signals generated succeedingly may be misjudged for the erroneous sync detection signals. As a result, the sync insertion and protection device 124 will erroneously generate the predetermined number of the sync insertion signals, based on the misjudgement, thereby causing damage to the data.
Besides, when a defect is detected, the lowpass filter 114 holds its output; if the held output value is not coincident with an average value, the playback clock
PLCK from the VCO 108 is out of sync (shifted) undesirably, which leads to a shift of the positions where the sync protection window signal and the sync insertion signal are to be generated.
It is therefore an aim of embodiments of the present invention to provide a sync detection device which stops generating sync insertion signals, when a sync detection signal is normally generated after a sync protection window signal is out of sync with the sync detection signal.
It is another aim of embodiments of the present invention to provide a sync detection device for preventing a sync protection window from being set according to sync noises.
It is still another aim of embodiments of the present invention to provide an optical disk player which prevents a playback clock from being out of sync even in case a defect is detected.
According to an aspect of the present invention, there is provided a sync detection device for an optical disk player comprising: a sync detector for detecting a sync signal from a signal read from an optical disk; a sync insertion and protection device for setting a sync protection window according to a sync detection signal from the sync detector in response to a reset signal, counting a playback clock generated from a voltage controlled oscillator to generate a sync protection window signal if the count value is coincident with a position where the sync signal is to be generated, and generating a sync insertion signal in response to a sync insertion request; a sync generator for outputting the sync detection signal if the sync detection signal is in sync with the sync protection window signal, and requesting the sync insertion and protection device to generate the sync insertion signal to output the sync insertion signal if the sync detection signal is out of sync with the sync protection window signal; and a sync noise canceller for counting the playback clock during generation of the sync detection signal, and generating the reset signal to the sync insertion and protection device if the count value reaches a predetermined value.
According to a second aspect of the invention, there is provided an optical disk player comprising: an optical disk; a pickup for reading data recorded on said optical disk; an amplifier for amplifying an output of said pickup; a binarizer for binarizing an output of said amplifier; a voltage controlled oscillator for generating a playback clock; a sync detection device for receiving said playback clock and an output of said binarizer to detect a sync signal therefrom; a phase detector for receiving said playback clock and the output of said binarizer to detect a phase difference therebetween; a lowpass filter for lowpass-filtering an output of said phase detector; an average value calculator for calculating an average value for an output of the lowpass filter when a defect is detected; and a switching circuit for providing said voltage controlled oscillator with the output of said lowpass filter when the defect is not detected, and providing said voltage controlled oscillator with an output of said average value calculator when the defect is detected.
Preferably, said sync detection device comprises: a sync detector for detecting a sync signal from a signal read from an optical disk; a sync insertion and protection device for setting a sync protection window according to a sync detection signal from the sync detector in response to a reset signal, counting a playback clock generated from a voltage controlled oscillator to generate a sync protection window signal if the count value is coincident with a position where the sync signal is to be generated, and generating a sync insertion signal in response to a sync insertion request; a sync generator for outputting said sync detection signal if the sync detection signal is in sync with the sync protection window signal, and requesting said sync insertion and protection device to generate the sync insertion signal to output said sync insertion signal if the sync detection signal is out of sync with the sync protection window signal; and a sync noise canceller for counting the playback clock during generation of the sync detection signal, and generating said reset signal to said sync insertion and protection device if the count value reaches a predetermined value.
For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings, in which:
Figure 1 is a schematic block diagram of an optical disk player according to the prior art;
Figure 2 is a block diagram of a sync detection and protection device of Figure 1 ;
Figure 3 is a schematic block diagram of an optical disk player according to a preferred embodiment of the present invention;
Figure 4 is a block diagram of an average value calculator of the player of Figure 3; and
Figure 5 is a block diagram of a sync detection and protection device of the player of Figure 3.
A preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Many specific details described in the specification and accompanying drawings are described for comprehensive understanding of the present invention.
However, as is known to anyone skilled in the art, the present invention can be implemented without the details.
In addition, detailed description of known operation and structure of the present invention is avoided lest it should obscure the subject matter of the present invention.
Referring to Figure 3, a pickup 202 reads data recorded on an optical disk 200, generates an RF signal according thereto, and provides an RF amplifier 204 with the RF signal. The RF amplifier 204 amplifies the RF signal and provides it to a binarizer 206. The binarizer 206 binarizes the output of the RF amplifier to generate binary data SDATA in series to a sync detection and protection device 210. The sync detection and protection device 210 receives the binary data SDATA and a playback clock PLCK generated from a voltage controlled oscillator (VCO) 208 to detect the sync signal therefrom, and protects the sync detection signal; in case the sync is not detected successfully, the sync detection and protection device 210 generates the sync insertion signal.
Further, the playback clock PLCK and the binary data
SDATA are applied to a phase detector 212. The phase detector 212 compares a phase of the playback clock PLCK with a phase of the binary data SDATA to detect a phase difference therebetween, and the comparison results are fed back to a switching circuit 218 via a lowpass filter 214. An average value calculator 216 calculates an average value for the output of the lowpass filter 214 for a predetermined time in case the defect is detected, and provides the average value to the switching circuit 218.
The switching circuit 218 provides the VCO 208 with the output of the lowpass filter 214 when the defect is not detected, and provides the VCO 208 with the output of the average value calculator 216 when the defect is detected.
Referring to Figure 4, the average value calculator 216 includes an analog-to-digital converter (ADC) 220 and an average value calculation circuit 222. The output of lowpass filter 214 is converted into digital data by ADC 220. The average value calculating circuit 222 receives the output of the ADC 220 to calculate its average value.
The calculated average value is provided to the switching circuit 218.
Referring to Figure 5, the sync detection and protection device 210 includes a sync detector 224, a sync insertion and protection device 232, and a sync noise canceller 234. The sync detector 224 is composed of a first register 226, a sync pattern decoder 228, and a sync generator 230. The first register 226, being a serialinput-parallel-output register, loads the binary data
SDATA in series according to the playback clock PLCK and provides the loaded binary data SDATA to the sync pattern decoder 228 in parallel. The sync pattern decoder 228 checks whether the binary data SDATA from the first register 226 is coincident with the sync pattern, and generates a sync detection signal to the sync generator 230 if the binary data SDATA is coincident with the sync pattern.
The sync insertion and protection device 232 sets the sync protection window according to the sync detection signal that the sync pattern decoder 228 has generated during resetting the sync protection window. After setting the sync protection window, the sync insertion and protection device 232 counts the playback clock PLCK, to generate the sync protection window signal to the sync generator 230 if the count value is coincident with a position where the sync signal is to be generated.
The sync generator 230 checks whether the sync detection signal is generated during generation of the sync protection window signal. If the sync detection signal is generated during generation of the sync protection window signal, the sync generator 230 outputs the generated sync detection signal as the sync signal.
However, if the sync detection signal is not generated during generation of the sync protection window signal, the sync generator 230 requests the sync insertion and protection device 232 to generate a sync insertion signal, and outputs the generated sync insertion signal as the sync signal.
The sync noise canceller 234 includes first and second counters 235 and 242, a second register 238, a comparator 240, G11C a reset signal generator 244. The first counter 236 counts the playback clock PLCK during generation of the sync detection signal, and loads the count value to the second register 238. The second register 238 holds the loaded count value whenever the sync detection signal is generated. The value held by the second register 238 is applied to the comparator 240. The comparator 240 compares the output value of the second register 238 with a count value for a normal sync detection signal, to generate a counting clock to the second counter 242 if the count values are the same to each other. If the counting value reaches a predetermined value, the second counter 242 generates a reset control signal to the reset signal generator 244. In response to the reset control signal, the reset signal generator 2^4 generates a reset signal to the sync insertion and protection device 232. For example, the reset signal generator 244 consists of a switching element which outputs the sync detection signal as the reset signal in response to the reset control signal. In response to the reset signal output from the reset signal generator 244, the sync insertion and protection device 232 resets the sync protection window according to the sync detection signal.
As described above, if the sync detection signal is normally generated after the sync protection window signal is out of sync with the sync detection signal, the sync detection and protection device stops generating the sync insertion signal, and outputs the sync detection signal as the sync signal, thereby preventing damage to the data due to the sync noises. Furthermore, in accordance with the present invention, the playback clock PLCK may not be out of sync (or shifted), even though the defect is detected.
While the present invention has been described in detail with reference to the specific embodiment, it is clearly understood that many variations can be made by anyone skilled in the art within the scope and spirit of the present invention. Thus, the appropriate scope hereof is deemed to be. in accordance with the claims as set forth below.
Claims (3)
- CLAIMS 1. A sync detection device for an optical disk player, comprising: a sync detector for detecting a sync signal from a signal read from an optical disk; a sync insertion and protection device for setting a sync protection window according to a sync detection signal from the sync detector in response to a reset signal, counting a playback clock generated from a voltage controlled oscillator to generate a sync protection window signal if the count value is coincident with a position where the sync signal is to be generated, and generating a sync insertion signal in response to a sync insertion request ; a sync generator for outputting said sync detection signal if the sync detection signal is in sync with the sync protection window signal, and requesting said sync insertion and protection device to generate the sync insertion signal to output said sync insertion signal if the sync detection signal is out of sync with the sync protection window signal; and a sync noise canceller for counting the playback clock during generation of the sync detection signal, and generating said reset signal to said sync insertion and protection device if the count value reaches a predetermined value.
- 2. An optical disk player comprising: an optical disk; a pickup for reading data recorded on said optical disk; an amplifier for amplifying an output of said pickup; a binarizer for binarizing an output of said amplifier; a voltage controlled oscillator for generating a playback clock; a sync detection device for receiving said playback clock and an output of said binarizer to detect a sync signal therefrom; a phase detector for receiving said playback clock and the output of said binarizer to detect a phase difference therebetween; a lowpass filter for lowpass-filtering an output of said phase detector; an average value calculator for calculating an average value for an output of the lowpass filter when a defect is detected; and a switching circuit for providing said voltage controlled oscillator with the output of said lowpass filter when the defect is not detected, and providing said voltage controlled oscillator with an output of said average value calculator when the defect is detected.
- 3. An optical disk player according to claim 1 or claim 2 and substantially as herein described with reference to figures 3 to 5.3. The optical disk player as claimed in claim 2, wherein said sync detection device comprises: a sync detector for detecting a sync signal from a signal read from an optical disk; a sync insertion and protection device for setting a sync protection window according to a sync detection signal from the sync detector in response to a reset signal, counting a playback clock generated from a voltage controlled oscillator to generate a sync protection window signal if the count value is coincident with a position where the sync signal is to be generated, and generating a sync insertion signal in response to a sync insertion request; a sync generator for outputting said sync detection signal if the sync detection signal is in sync with the sync protection window signal, and requesting said sync insertion and protection device to generate the sync insertion signal to output said sync insertion signal if the sync detection signal is out of sync with the sync protection window signal; and a sync noise canceller for counting the playback clock during generation of the sync detection signal, and generating said reset signal to said sync insertion and protection device if the count value reaches a predetermined value.4. A sync detection device substantially as herein described with reference to Figures 3 to 5. AMENDMENTS TO THE CLAIMS HAVE BEEN FILED AS FOLLOWS :1. An optical disk player comprising: an optical disk; a pickup for reading data recorded on said optical disk; an amplifier for amplifying an output of said pickup; a binarizer for binarizing an output of said amplifier; a voltage controlled oscillator for generating a playback clock; a sync detection device for receiving said playback clock and an output of said binarizer to detect a sync signal therefrom; a phase detector for receiving said playback clock and the output of said binarizer to detect a phase difference therebetween; a lowpass filter for lowpass-filtering an output of said phase detector; an average value calculator for calculating an average value for an output of the lowpass filter when a defect is detected; and a switching circuit for providing said voltage controlled oscillator with the output of said lowpass filter when the defect is not detected, and providing said voltage controlled oscillator with an output of said average value calculator when the defect is detected.2. An optical disk player according to claim 1, wherein the average value calculator includes an analog-todigital converter and an average value calculation circuit.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019970074181A KR100258332B1 (en) | 1997-12-26 | 1997-12-26 | Sync. detector and optical disc reproducer thereby |
| GB9811719A GB2332790B (en) | 1997-12-26 | 1998-06-02 | Sync detection device and optical disk player having the same |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB0000163D0 GB0000163D0 (en) | 2000-03-01 |
| GB2343569A true GB2343569A (en) | 2000-05-10 |
| GB2343569B GB2343569B (en) | 2000-06-21 |
Family
ID=26313774
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0000163A Expired - Fee Related GB2343569B (en) | 1997-12-26 | 1998-06-02 | Optical disc player |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2343569B (en) |
-
1998
- 1998-06-02 GB GB0000163A patent/GB2343569B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| GB2343569B (en) | 2000-06-21 |
| GB0000163D0 (en) | 2000-03-01 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20090602 |