JPH06267194A - Device for detecting synchronizing information - Google Patents

Abstract

PURPOSE:To provide a synchronizing information detecting device capable of preventing a pattern similar to a synchronizing signal from erroneously being detected as the synchronizing signal. CONSTITUTION:By the synchronizing information detecting device in an information reproducing device, data is reproduced by detecting the synchronizing signal from a storage medium recording the synchronizing signal together with the data. A detection window generation means 3 outputting the first detection window signal 13 at the timing when the synchronizing signal is regenerated outputs a second detection window signal 15 when a first detection window signal 13 is outputted at the timing and an output interval different from the timing. A second detection operation different from first detection operation is performed with the output of the second detection window signal by a synchronizing signal detection means 4 performing the first detection operation of the synchronizing signal with the first detection window signal 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronous information detecting device for an information reproducing device for an information storage medium such as an optical disk.

[0002]

2. Description of the Related Art Conventionally, an information storage medium such as an optical disk has tracks formed on its surface, and each track is divided into a plurality of sectors. As shown in the structure of FIG. 4, a conventional optical disc is composed of sectors 41 in which a track 40 is divided at equal intervals.

The sector 41 comprises an address area 42 for recording address data and a data area 43 for storing user data. The address area 42 is composed of a synchronization signal 44 indicating the origin of the address data, address data 45, and an error detection code 46. Further, the synchronization signal 44 is composed of several kinds of M symbols 47 of N bit length.

An information reproducing apparatus for recording and reproducing user data using such an information storage medium needs a function of reading address data from an address area in order to access a designated sector. FIG. 3 shows an address data reading section of a conventional information reproducing apparatus.

As shown in FIG. 3, in a synchronous information detecting device 30 composed of a detection window generating circuit 32 and a synchronous signal detecting circuit 33, the synchronous signal detecting circuit 33 is read from an optical disk by an optical head (not shown). A sync signal in the address area is detected from the reproduction signal 34 and a detection signal 35 is output.

The error detection circuit 31 reads the address data and the error detection code from the reproduction signal 34 from the optical disk by using the detection signal 35 of the synchronization signal as a trigger to detect an error. If there is no error, the address read OK signal 36 is output and the address data is output to the outside via the signal line 38.

The detection window generation circuit 32 activates the internal timer by using the output of the normal address read OK signal 36 as a trigger, and outputs the detection window signal 37 at the timing when the synchronizing signal of the sector immediately after this is reproduced. Further, the synchronization signal detection circuit 33 performs the detection operation of the synchronization signal by the detection window signal 37 being output from the detection window generation circuit 32.

[0008]

However, in the prior art as described above, for example, when the address reading of the sector is impossible immediately after the power of the device is turned on, immediately after the track seek, or immediately before, the detection window generating circuit 32 Since the timer cannot be operated, the output control of the detection window signal 37 cannot be performed. Therefore, the detection window signal 37 is continuously output until the synchronization signal is detected.

In such a case, the sync signal detection operation is carried out at a timing other than the timing at which the sync signal is reproduced, and the sync signal is detected even for the reproduced signal from the data area, address data, and error detection code. Is done.

Normally, the sync signal is a pattern that does not exist as a data pattern so that the data patterns in these areas are not erroneously detected as a sync signal.
However, since a pattern similar to the sync signal may exist in these areas, the similar pattern and the defective pattern of the medium may be combined to form a pattern very similar to the sync signal. In this case, there is a problem that the sync signal detection circuit 33 erroneously detects this pattern as a sync signal.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a sync signal detecting device capable of preventing a pattern similar to a sync signal other than the sync signal from being erroneously detected as a sync signal.

[0012]

In order to achieve the above object, the sync signal detecting apparatus according to the present invention detects the sync signal from a storage medium in which the sync signal is recorded together with data. In the synchronous information detecting device of the information reproducing device for reproducing the data by
Detection window generating means for outputting a first detection window signal at the timing at which the synchronization signal is reproduced, and synchronization for outputting a synchronization signal detection signal by performing a first detection operation of the synchronization signal by the first detection window signal. Signal detection means, and the detection window generation means outputs a second detection window signal when the first detection window signal is output at a timing and an output period different from the timing, and the synchronization signal detection means. The second detection operation different from the first detection operation is performed by the output of the second detection window signal.

Further, in the synchronization information detecting device according to the invention described in claim 2, in the synchronization information detecting device according to claim 1, the second detection operation is performed by outputting the second detection window signal. It is based on the changed threshold value for determining the synchronization signal.

[0014]

According to the present invention, in the synchronous information detecting device of the information reproducing device for reproducing the data by detecting the synchronous signal from the storage medium in which the synchronous signal is recorded together with the data, the synchronous signal from the normal detection window generating means is used. The first detection window signal is output at the timing at which is reproduced, and the first detection window signal causes the synchronization signal detection means to perform the first detection operation of the synchronization signal. The signal detection signal is output.

On the other hand, when the first detection window signal is output at a timing or an output period different from the timing at which the normal synchronization signal is reproduced, the second detection window signal is output, whereby the synchronization in the synchronization signal detecting means is performed. The signal detection is performed according to a second detection operation different from the first detection operation.

That is, the timing at which the first detection window signal is output is determined by the operation of the internal timer of the detection window generation means. For example, the address reading of the sector immediately after the power supply to the device or immediately after or immediately after the track seek is performed. It is impossible and the timer does not operate.
When the output control of the detection window signal is not possible and the detection operation of the synchronization signal is performed on the reproduction signal other than the synchronization signal, the second detection window signal is output, and the synchronization signal detection means outputs the second detection window signal. Sync signal detection is usually the first
This is performed according to a second detection operation different from the above detection operation.

Therefore, the second detection operation is normally erroneously detected for a pattern similar to a sync signal in which the reproduction signal other than the sync signal is erroneously detected as the sync signal in the first detection operation. It is possible to prevent erroneous detection of the sync signal by setting it so as not to cause.

In the present invention, as the second detection operation for preventing erroneous detection, the threshold for synchronizing signal determination is changed and set by the output of the second detection window signal, and based on this changed threshold. The synchronization signal is detected.

Generally, in the sync signal detecting means, the reproduced signal is at least the sync signal (M symbols of N bit length).
Are taken into a shift register having a number of stages (N × M stages) capable of handling B in a bit unit, the output of the shift register is decoded in a symbol unit in the decoder, and the coincidence signal of the symbol output from the decoder is previously stored in the majority circuit. When n or more threshold values that have been set are input, it is determined that a sync signal has been detected.

Here, if a match signal of n or more thresholds is input by a similar pattern other than the sync signal, it is erroneously determined to be the sync signal detection. However, in the present invention, a reproduction signal other than the sync signal is detected. The second detection window signal is output when the synchronization signal is detected by the above-mentioned method, whereby the threshold value n is set to a larger value n ′ (n <n ′, 0 <
n ′ ≦ M), and in the second detection operation, the synchronization signal detection is determined based on this changed threshold value n ′, so that erroneous detection due to a similar pattern is less likely to occur, and depending on the threshold value n ′, No false positives occur.

[0021]

EXAMPLES The present invention will be described below with reference to examples.
FIG. 1 is a schematic configuration diagram of an address data reading unit of an information reproducing apparatus using a synchronous information detecting apparatus according to an embodiment of the present invention. As shown in the figure, the detection window generation circuit 3
In the synchronous information detecting device 1 including the synchronous signal detecting circuit 4 and the synchronous signal detecting circuit 4, the synchronous signal detecting circuit 4 detects and detects the synchronous signal in the address area from the reproduction signal 10 read from the optical disk by the optical head (not shown). The signal 11 is output.

The error detection circuit 2 uses the detection signal 11 of the synchronization signal as a trigger to read the address data and the error detection code from the reproduction signal 10 from the optical disk to detect an error. If there is no error, address read OK signal 1
2 is output, and the address data is output to the outside via the signal line 14.

The detection window generating circuit 3 operates the internal timer by using the output of the normal address read OK signal 12 as a trigger, and outputs the first detection window signal 13 at the timing when the synchronizing signal of the sector immediately after this is reproduced. . Further, the synchronization signal detection circuit 4 detects the synchronization signal according to the first detection operation by outputting the first detection window signal 13 from the detection window generation circuit 3.

That is, as shown in FIG. 2, in the sync signal detection circuit 4, the reproduction signal 10 is taken into the shift register 20 having the number of stages capable of handling at least the sync signal in bit units by the clock 25 synchronized with the data. Here, it is assumed that the synchronization signal is composed of M N-bit-length symbols. Therefore, the shift register 2 has at least N × M stages.

The output 26 from the shift register 20 is decoded by the decoder 21 in symbol units. This decoding is performed by collating the preset sync signal pattern with the output 26 of the shift register 20 in symbol units. Decoder 21 outputs M number of symbol coincidence signals 27 and introduces them into majority circuit 22.

The threshold value setting circuit 24 is preset with a threshold value n for the majority circuit 22 to determine whether to detect a synchronization signal. Therefore, the majority circuit 22 inputs N or more threshold values of the symbol match signals 27, determines that the synchronization signal is detected, and outputs the determined detection signal 28. The signal 28 is gated by the AND gate 23, but is output as the detection signal 11 of the synchronization signal if the first detection window signal 13 is enabled.

However, if the address reading of the sector is impossible immediately after the power supply of the device is turned on, immediately after the track seek, or immediately before, the detection window generation circuit 3 cannot operate the internal timer, and as described above,
It is not possible to control so that the detection window signal 13 of 1 is output only at a predetermined timing. Therefore, the detection window circuit 3 continues to output the first detection window signal 13 until the synchronization signal is detected.

Therefore, the detection window generating circuit 3 outputs the timer non-operation signal 15 as the second detection window signal when the internal timer is not operating. In the sync signal detection circuit 4, the first detection window signal 13 from the detection window generation circuit 3 performs a sync signal detection operation on a reproduced signal other than the sync signal. At this time, the sync signal is not detected. It is performed according to the second detection operation by the timer non-operation signal 15 output at the same time.

In the second detection operation, the timer non-operation signal 15
As a result, circuit parameters and the like are changed, and erroneous detection of a pattern similar to a sync signal other than the sync signal is less likely to occur than in the normal case. In this embodiment, the detection operation is performed by changing the threshold value n at the time of determining the synchronization signal detection.

As described above, in the sync signal detection circuit 4, the threshold information 29 is output from the threshold setting circuit 24 in the majority decision circuit 22, and the sync signal is detected from the threshold n and the symbol match signal 27 input from the decoder 21. A decision is made. Here, the threshold value n is changed to a larger value n ′ (n <n ′ ≦ M) by inputting the timer non-operation signal 15 to the threshold value setting circuit 24.

Therefore, in the second detecting operation of the synchronizing signal, the majority decision circuit 22 does not determine the synchronizing signal detection unless the symbol matching signal 27 is input to the threshold value n'or more, so that the threshold value n'is closer to M. By setting, it is possible to avoid erroneously detecting a signal pattern similar to the synchronization signal as the synchronization signal. Therefore, the symbol match signal 27 is input only at the threshold value n ′ or above only in the case of the true synchronization signal, and at this time, the detection signal 11 of the synchronization signal is output.

As described above, in the synchronization information detecting apparatus of the present embodiment, when the output control of the detection window signal cannot be performed and the detection operation of the synchronization signal is executed even for the reproduction signal other than the synchronization signal, the synchronization signal is detected. It is possible to avoid erroneously detecting a signal pattern that is very similar to that as a synchronization signal.

In the above embodiment, the synchronization signal detection circuit 4 performs the second detection operation for preventing erroneous detection, which is different from the normal first detection operation, by the second detection window signal.
Although the threshold value of the majority circuit 22 is changed, the present invention is not limited to this. For example, two different sync signal detection circuits are provided as the first and second detection operations, and the detection window signal is detected. The circuit of these two systems may be switched according to the change of Further, means for changing the level of binarizing the reproduction signal by changing the detection window signal can be considered.

Further, the detection window generating circuit outputs the detection window signals of the two modes (first and second detection window signals) according to the situation.
A configuration having two or more modes switchable may be adopted. In that case, the synchronization signal detection circuit is provided with a detection operation corresponding to each mode.

In the above embodiments, only the sync signal 44 indicating the origin of the address data is mentioned, but the present invention applies to all mark signals detected by enabling the detection window, for example ISO 5.25 inch magneto-optical. This is effective for sector marks, address marks, SYNC, RESYNC, etc. in the disc format.

[0036]

As described above, the present invention is very similar to the sync signal even when the output of the detection window signal cannot be controlled and the sync signal detection operation is performed on the reproduced signal other than the sync signal. This has the effect of preventing erroneous detection of the signal pattern.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a synchronization information detecting device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a sync signal detection operation in the sync signal detection circuit 4 of FIG.

FIG. 3 is a schematic configuration diagram of a conventional synchronization information detection device.

FIG. 4 is an explanatory diagram showing a track configuration of an optical disc.

[Explanation of symbols]

 1, 30: Synchronous information detection device 2, 31: Error detection circuit 3, 32: Detection window generation circuit 4, 33: Synchronous signal detection circuit 10, 34: Reproduction signal 11, 35: Synchronous signal detection signal 12, 36: Address Read OK signal 15: Timer non-operation signal 20: Shift register 21: Decode 22: Majority circuit 23: AND gate 24: Threshold setting circuit 27: Symbol match signal

Claims (2)

[Claims] 1. A synchronous information detecting device of an information reproducing device for reproducing the data by detecting the synchronous signal from a storage medium in which the synchronous signal is recorded together with the data, in a timing at which the synchronous signal is reproduced. Detection window generating means for outputting a first detection window signal, and a first synchronization signal generated by the first detection window signal.
Synchronizing signal detecting means for performing a detecting operation for outputting a synchronizing signal detecting signal, wherein the detecting window generating means outputs a first detecting window signal at a timing and an output period different from the timing. 2. A synchronization information detecting device, which outputs two detection window signals, and wherein the synchronization signal detecting means performs a second detection operation different from the first detection operation by the output of the second detection window signal. 2. The second detection operation according to claim 1, wherein the second detection operation is based on a threshold for determining a synchronization signal which is changed and set by the output of the second detection window signal. Synchronous information detection device.