JPH0341674A - Recording status determination device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a method for reproducing digital information from a recording medium.
The present invention relates to a recording state determination device having a PLL circuit for synchronizing data.

[Conventional technology] In general, when recording digital information on a recording medium such as a tape or a disk, if there is no special reproduction signal for the clock, a circuit such as a PLL (phase locked loop) circuit is used for data synchronization. Self-clocking means are required.

Furthermore, when using a PLL circuit, a certain pattern signal is required to synchronize the clocks of the PI and L circuits with data.

FIG. 4 is a schematic diagram showing a recording format on a general recording medium.

This recording medium is divided into multiple sectors. One sector consists of a preformat section in which signals are recorded in advance, and a data recording section in which data can be recorded, reproduced, and erased.

The preformat section includes a sector mark section that serves as a mark of the starting point of the sector, and an address information section in which address information of the sector is recorded.

On the other hand, the data recording section has the above-mentioned PLL synchronization pattern section at the beginning, followed by a data mark section.

This is followed by the data section.

When playing a recording medium having such a recording format, after confirming the sector address using the sector mark as a reference, the PLL synchronization pattern is used to confirm the sector address.
The LL circuit creates a clock synchronized with the input signal, finds the starting point of the data section using the data mark, and reads the data.

As the PLL synchronization pattern, a periodic pattern such as "1010..." or "100100" or "10001000" is used.

[Problem 8 to be solved by the invention] However, with such conventional technology, the signal at the original position may disappear during playback (dropout) due to defects on the recording medium or poor S/N ratio, or the opposite problem may occur. If an unnecessary pulse (extra pulse) is generated at a position where it should not be present, it may cause malfunction of the PLL circuit.

In particular, when a dropout occurs in the PLL synchronization pattern, the frequency of the PLL clock momentarily changes to a lower value, causing a false lock to occur at a lower number of cycles. In other words, there is a risk that the frequency of the PLL clock will become stable at a frequency that is a fractional ratio of the normal number of cycles.

Conversely, if an extra pulse occurs in the PLL synchronization pattern, there is a risk of false locking at high frequencies.

By the way, in general, when trying to shorten the PLL synchronization time in order to shorten the length of the PLL synchronization pattern,
A method is often used in which the fill and refill time constants are reduced by the period of the PLL synchronization pattern. However, if this method is adopted, there is an increased risk that normal synchronization will not be achieved due to dropouts or e-trapulses.

Further, as the pull-in range of the PLL is widened, the incidence of adverse effects due to draw 2 pull-out and extra pulses increases.

If a normal PLL clock cannot be obtained within the PLL synchronization pattern period due to such dropouts or extra pulses, the data recorded in that sector cannot be reproduced as a whole.

Furthermore, dropout and extra pulses increase due to deterioration of the S/N ratio due to aging of the recording medium or environmental changes, and due to adhesion of dust or scratches on the medium. And as a result of this,
A situation arises in which a certain sector on a recording medium that previously could reproduce data becomes unable to reproduce data due to dropout or an increase in extra pulses.

SUMMARY OF THE INVENTION An object of the present invention is to provide a recording state determination device that can determine whether the recording state on a recording medium is good or bad based on dropouts or extra pulses in a PLL synchronization pattern.

[Means for Solving the Problems] The present invention is characterized by counting dropouts or extra pulses in a PLL synchronization pattern recorded on a recording medium, and determining whether the recording state is good or bad based on the count value.

[Operation J] According to the present invention, by counting dropouts or extra pulses in the PLL synchronization pattern recorded on the recording medium and determining whether the recording condition is good or bad based on the value, it is possible to ensure that information is correctly transmitted to the recording medium. You can check whether it is recorded.

This recording state determination device can be incorporated into various recording and reproducing devices to check the recording state of information after a recording operation or during a reproducing operation, and if it is defective, the recording operation can be retried.
It is possible to adopt a configuration in which measures such as alternative processing of recording sectors are performed.

Moreover, it is possible to configure a quality inspection device that manages the quality of a recording medium using such a recording state determination device.

[Embodiment] FIG. 1 is a block diagram showing an embodiment of a recording state discriminating device according to the present invention.

This recording state discriminating device includes a phase comparison circuit 1 which inputs a reproduced binary pulse signal from a recording medium and outputs a normal synchronization pattern pulse and an extra pulse, a counter 2 which counts the normal sync pattern pulse, and an extra pulse. a latch comparator 4 that latches the count value of the counter 2 and compares it with the allowable minimum mA, a latch comparator 5 that latches the count value of the counter 2 and compares it with the allowable maximum value B, and each latch. O outputs a judgment signal based on the output of comparator 4.5
It has an R circuit 6 and a timing control circuit 7 that controls the reset timing of each counter 2.3 and the latch timing of each latch comparator 4.5 based on the data read gate signal.

FIG. 2 is a circuit diagram showing details of the phase comparator circuit l in the recording state discriminating device.

FIG. 3 is a time chart showing signal waveforms at each point in the one-phase comparator circuit 1.

The reproduced binary pulse signal a reproduced from the recording medium is inputted from the input terminal 10 of the phase comparator circuit l.

In addition, this phase comparator circuit 1 has 52 delay circuits 1.
1.12, a window C is created, and if a rising edge of the reproduced binary pulse signal a exists within the period of this window C, the pulse is normal. In other words, no dropout occurred.

Therefore, if the pulses of the reproduced binary pulse signal a are sent at a normal cycle, the same number of normal synchronization pattern pulses d will be generated at the output terminal 13. However, as shown in FIG. 3, when dropout occurs, the number of pulses d decreases accordingly.

Further, a window g is created by the action of the delay circuits 11 and 12, and if there is a rising edge of the reproduced binary pulse signal a within the period of this window g, it is considered to be an extra pulse.

Therefore, if the pulses of the reproduced binary pulse signal a are sent at a normal cycle, no extra pulse h will appear at the output terminal 14. However, as shown in FIG. Output terminal 1 according to the number
Extra pulse h is output at 4.

Therefore, the normal synchronization pattern pulse d and the extra pulse h outputted from such a phase comparator circuit 1 are
Counter 2.3 counts within the period of the synchronization pattern.

Then, when the number of positive 1m pattern pulses is smaller than the predetermined minimum allowable value A, the latch comparator 4
It is assumed that there are too many dropouts and an NG signal is output.

Furthermore, when the number of extra pulses is larger than a predetermined maximum allowable value B, the latch comparator 5 outputs an NG signal.
Output a signal.

These NG signals are inputted to a controller or the like of the information recording/reproducing apparatus via the OR circuit 6.

Therefore, on the information recording and reproducing apparatus side, it is possible to determine whether the recording state is good or bad based on this NG signal (recording state quality determination signal).

If it is determined that the recording condition is poor, for example, the recording operation may be retried after the recording operation is completed.
Alternatively, take measures such as using alternate sectors or displaying this recording medium as unusable.

Additionally, if it is determined that the recording condition is poor during playback operation, it is possible to retry the playback, display an indication that the medium recording condition has worsened, or even re-record the sector. can.

Note that an application in which the device automatically performs these treatments is also conceivable.

An embodiment of the present invention has been described above.

For example, the specific circuit configuration etc. are not limited to the above embodiments.

Further, in the above embodiment, the case where the recording state determination device is mainly incorporated into an information recording/reproducing device has been described, but it is also possible to configure a recording medium quality inspection device using such a recording state determination device. . That is, this quality inspection device has a function of recording and reproducing inspection data on a recording medium to be inspected, a function of determining the recording state by the method explained in the above embodiment by this reproduction, and a function of determining the recording state. It also has a function to output the determination results on a display or printer. If the recording state of the inspection data is poor, it is assumed that the recording medium is defective, and treatment is taken.

[Effects of the Invention] According to the present invention, by determining whether the recording state of information on a recording medium is good or bad, deterioration of the S/N ratio due to aging of the recording medium or environmental changes, as well as dust, scratches, or defects on the medium can be detected. It has the effect of minimizing the troubles that occur.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a recording state discriminating device according to the present invention. FIG. 2 is a circuit diagram showing details of the phase comparison circuit in the recording state discriminating device of the same embodiment. FIG. 3 is a time chart showing signal waveforms at each point in the phase comparator circuit. FIG. 4 is a schematic diagram showing a recording format on a general recording medium. DESCRIPTION OF SYMBOLS 1... Phase comparison circuit, 2.3... Counter, 4.5... Latch comparator, 6... OR circuit, 7... Timing control circuit, 11.12... Delay circuit.

Claims (5)

[Claims] (1) An apparatus for determining the recording state of digital information, which counts dropouts or extra pulses in a PLL synchronization pattern recorded on a recording medium, and determines whether the recording state is good or bad based on the counted value. (2) It has a recording state determination unit that counts dropouts or extra pulses in the PLL synchronization pattern recorded on the recording medium and determines whether the recording state is good or bad based on the count value, and after the recording operation of digital information is completed, A digital information recording and reproducing device characterized by checking the recording state of this information. (3) It has a recording state determination unit that counts dropouts or extra pulses in the PLL synchronization pattern recorded on the recording medium and determines whether the recording state is good or bad based on the count value, and during the reproduction operation of digital information, A digital information recording and reproducing device characterized by checking the recording state of this information. (4) The digital information recording and reproducing apparatus according to claim (2) or (3), wherein a predetermined action is taken when the recording state determining section determines that the recording state is poor. (5) In a quality inspection device for a recording medium that records digital information, a recording state in which dropouts or extra pulses in a PLL synchronization pattern recorded on the recording medium are counted, and the quality of the recording state is determined based on the count value. A quality inspection device for a recording medium, comprising a determination section and a determination result output section that outputs a determination result by the recording state determination section.