JPH0469865A - Data recording and reproducing device - Google Patents

Abstract

PURPOSE:To reduce the read error rate by setting a reproducing clock position in an optimum position without being influenced by an amplitude value of a regenerative signal. CONSTITUTION:A PLL reproducing clock is delayed by a delay element 10. One of plural clocks delayed in different delay amts respectively is selected by a selector 11 and supplied to an A/D converter 7. A delay clock selecting operation is performed in prescribed order at the time of deciding an optimum clock by a selecting signal 19 for controlling the operation of the selector 11, and an operation after deciding, is carried out so as to select a delayed clock decided as the optimum. A deciding operation by a deciding circuit 12 is performed with a digital data after A/D conversion, and a delay clock 16 showing an optimum value estimated from a max. value or min. value even or a variable amt. of the data is regarded as the optimum delay clock. Now, on the other hand, plural data values by the same delay clock 16 are picked out and processed to be averaged, so that the optimum delay clock is decided. Thus, since the decision is performed by using the digitalized data, the deciding result with high accuracy can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method and apparatus for adjusting the phase difference yAv between a reproduced signal and a reproduced clock for signal detection during data reproduction.

[Conventional technology]

In conventional magnetic disk devices and optical disk devices, as a method of obtaining a clock that is synchronized with the recorded data when reading information, a phase pull-in area called VF○ is provided at the beginning of the recorded data, and a clock is generated in this area. P.I.
Mainly used is a self-clocking method that performs frequency and phase synchronization of the (Phase Loekl, o op) circuit and further fine-tunes the phase synchronization by detecting changing points in the recording data. It is used. but,
This method requires a circuit with high-speed synchronization characteristics, which is a problem when improving linear recording density.
”

On the other hand, in an optical disk device, the laser beam is
Tracking for correct irradiation (as Fubo,
A guide groove is provided on the disk 5, and this guide groove is r.

The method that detects the analyzed light is mainly used.

However, with this method, errors occur due to factors such as distortion of fIS' and inclination of the optical head2, making it difficult to achieve stable tracking control. (In order to solve this problem, a servo area for obtaining servo information instead of a guide groove is arranged at a constant interval at the intersection with a data area for recording and reproducing data, and a discrete control system is constructed. A sample servo force formula has been developed to
A synchronized clock for accurately reading servo information from the servo area is always required, and the servo area also includes a reference signal for obtaining the clock.

Therefore, if data is recorded and reproduced using this tarock, the VF○ area and high-speed synchronization characteristics as in the self-clocking method described above can also be achieved.
Suitable for high density as no circuit is required.

ing.

However, even with this sample servo method, a phase shift occurs between the recorded data and the clock due to various factors.

One of the factors is the peak position detection error of the reference signal. Normally, the peak position of the reference signal is the optimal position for signal reading, and the change point of the read clock is synchronized here, but due to the delay in the peak detection circuit, the peak position is delayed from the actual beat position. The detection signal 4B is output, and the clock is synchronized therewith.

Therefore, initial adjustment is performed by inserting a delay adjustment element such as a delay line into the clock or reproduced signal, but the delay amount may fluctuate due to humidity or aging of this delay amount adjustment element or peak detection circuit. Therefore, it is always in the optimal state (o) (not ′j).

Another factor is a delay in the circuit through which the recording signal passes during recording. Regarding this as well, although the overall delay amount is initially set by the delay plate adjusting element so that recording is performed at the optimum position, it is still immune to fluctuations due to temperature and aging.

Furthermore, C
Since the format of the reproduction signal differs between the preformat area formed at the time of disc manufacturing and the data area where data is recorded and reproduced later, the reproduction signal is inputted to the demodulation circuit via separate circuits. Therefore, it is necessary to adjust the amount of delay so that both signals can be detected at the same clock timing, but the same fluctuations as in the first two occur in this regard.

Such a phase shift becomes larger when recording and reproduction are performed using different drive devices. Also,
The higher the recording bit rate and the shorter the bit period, the greater the influence on the error rate during reproduction. Precedent button, which solves this problem.

For example, Japanese Patent Application Laid-Open No. 63-244448 can be mentioned. Here, we will solve the problem by comparing the sample value of the preformat signal with the sample value of the signal written at the same time as the append information at the beginning of the append signal, and adjusting the delay of the sampling clock of the append signal so that the two match. I'm trying.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into account the difference in playback level between the preformat section and the additional write section. That is, in an actual disc, the reproduction signal level of the preformat section and the reproduction signal level of the write-once section are not the same, but differ greatly depending on the recording mechanism and material.

Therefore, in a drive device that can handle multiple types of disks, it is not possible to obtain the optimum value of the phase.

SUMMARY OF THE INVENTION An object of the present invention is to provide a data recording and reproducing apparatus that obtains an optimal signal reading clock position regardless of the reproduction signal level.

[Means to solve the problem]

In order to achieve the above object, the present invention reads continuously recorded data synchronization signals by sequentially switching a plurality of clocks with different data acquisition timings, and then selects the optimal one from the obtained series of data. The timing clock was selected to read the subsequent information.

Furthermore, the present invention reads a data synchronization signal that is repeatedly recorded at a constant cycle by sequentially switching a plurality of clocks with different data acquisition timings.
A clock with optimal timing was selected from the series of data obtained, and subsequent information was read using this clock.

[Effect]

The delay element provides a delay to the PLL recovered clock.

A selection device selects one of the plurality of clocks delayed by different amounts of delay and supplies the selected clock to the A/D conversion device. The selection signal that controls the operation of the selection device performs the delayed clock selection operation in a predetermined order when determining the optimal clock, and after the determination, operates so that the delayed clock determined to be optimal is selected. The determination operation in the determination device is A
A delay clock that is performed on the digital data after /D conversion and shows the maximum value, the minimum value, or the optimal value estimated from the amount of data fluctuation is defined as the optimal delay clock. Also here, a plurality of data values based on the same delayed clock are sampled and averaged to determine the optimum delayed clock. In this way, since the determination is made using digitized data, highly accurate determination results can be obtained.

〔Example〕

Hereinafter, five embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram of a sample servo system for an optical disc. In the sample servo method, the servo area is used by the drive device to obtain servo information.

Data areas where data is written, read, and erased are arranged alternately. The servo area has pits formed during disk manufacturing, and includes a clock synchronization pit used for clock reproduction, a no-signal area from which focus manufacturing information is obtained, and a set of wobble pits from which a track control signal is obtained.

In the wobble bit, pits are arranged offset from the center of the track on both sides thereof, and by detecting the difference between the two, the amount of deviation from the track is detected. Third
The figure shows an example of the configuration of the servo area. Although the actual servo area may include pits with other functions (for example, access track crossing detection pits), the presence or absence of these pits does not affect the features and operation of the present invention, so they are shown in the figure. Not yet. In the data optical disk, the combination of the servo area and the data area shown in FIG. 2 is considered to be one segment l~, and a plurality of segments are collected to form a sector.

FIG. 4 shows an example of the configuration of sectors according to this embodiment. A sector is divided into an ID area in which ID information such as a track number and sector number is stored, a synchronization area to be described later, and a user area in which the user records, reproduces, and erases data. I
The D information pits are formed during disk manufacturing, similar to the servo information pits described above. This is Puri Pit. FIG. 1 shows an example of an optical disk drive device including a delay adjustment circuit according to the present invention. Here, the playback operation will be explained. The optical disc 1 is rotated at a predetermined rotational speed by a spindle motor 2, and is irradiated with a reproduction laser beam from an optical pickup 3. Information recorded on the disk includes servo information and i
The pre-pit part of the D information and the postscript part using a punching type or a phase change type are read by the size of the reflective sell, and the postscript part using a magneto-optical method is read from the change in the deflection angle of the reflected light due to the recording magnetic field. . The reflected light from the disk is converted into an electrical signal by a photodetecting element in an optical bit up circuit 3, and then sent to a preamplifier 4L. Here, signal processing compatible with the recording method described above and amplification to the No. 1 level, which can be handled by each subsequent circuit, are performed, and a reproduced signal is obtained. The reproduced signal is input to the peak detection circuit 5.

The peak position of the clock synchronization pin I in the servo area is detected. This peak position detection belief)) 1. ,,,
1. .

A Glock reproducing circuit 6 consisting of a Glock reproducing circuit 6 generates a reproducing clock synchronized with a reproducing pit signal.

In the conventional device, this reproduced clock directly served as the sampling clock of the A/D converter 7, and converted the reproduced signal into a digital value. However, in the present invention, a reproduced clock is manually input to the delay element 10 to generate a plurality of delay clocks (different kinds in this embodiment).

Selector 11 selects 1 from five clocks. - Select a wooden clock and supply it to the A/D converter 7. The amplitude data converted into a digital value is used in the demodulation circuit 8 to demodulate the data area, and the I-ranking error detection circuit 9 uses it to detect an error signal by calculating the difference between wobble pits in the servo area. Furthermore, the amplitude data is determined by the judgment circuit 1.
2 and controls the selector 11 described above.

FIG. 5 shows a peak detection method. A differential signal is obtained by differentiating the reproduction signal 13 of the clock synchronization pit.

Since this signal crosses Ov at the peak position of the reproduced signal 13, by detecting this position, the peak detection signal 14
is obtained. The peak detection signal is shown in FIG.
By inputting it to the circuit, the regenerated clock 15 in FIG.
is obtained. This reproduction clock is used to reproduce prepit signals in the servo area and ID area. When reproducing the user area, first tarokk selection is performed in the synchronization area. In the example shown in FIG. 1, there are different types of clocks that can be selected, but the present invention is not limited to this number. The optimal configuration can be adopted by taking into consideration the scale. An example of the structure of the H-shaped element 10 shown in FIG. 1 is shown in FIG. 7, and a tie 11 chart is shown in FIG. 8. Here, the delay clock 3 is set to the same timing as the reproduced clock, and the delay variation amount Δt is set. In order to obtain a clock with a timing earlier than the regenerated clock, an inverted regenerated clock (No. 1) is used, and the delay line of the delay time τ.
It has a combination of delay lines. Here, if the period of the reproduced clock is ゛, then `r-τ. The relationship is +2xtL. In the synchronization area, signals 1010 .

The recording pattern in this synchronization area requires that the peak value of the pit playback signal is not affected by the pits on both sides, so it depends on the recording and playback characteristics of the recording medium.
It is also necessary to form a pattern with N intervals apart. The selector 11 outputs one output from five inputs, and is controlled by three selection signals, to which ``ooo'' to 8100'' are assigned. This selection signal is controlled by the determination circuit I2. As shown in FIG. 9, the determination circuit 12 first sets the selection signal to 000#. As a result, the delayed clock is supplied to the A/D converter 7, and the reproduced signal is encoded into a digital value in one pulse.

The encoded data is held in a numerical register within the determination circuit 12. What is E1 at the rising edge of the next clock? Since it is an O' signal, it is not used, and the next (j ゛1
The data of 1 is encoded by setting the selection signal 19 to 001'. In the same way, the remaining two signals "1" are encoded, and the one showing the maximum value is added to 3L, and the selected signal at that time is determined to be the optimal clock position.In FIG. Because it is encoded, the digital data can take values from 0 to 255. If the clock reading position deviates from the peak position of the reproduced signal, the read amplitude data will become small. The maximum width can be obtained by Since the select signal is '011', the optimal clock is delayed clock 4, which is delayed by one from the recovered clock, to read the user area.Also, in order to read the servo area, the select signal is '010'. Since the delay clock 3 is suitable, the determination circuit 12 alternately switches the select signal to ', 010', ?01bi, and always
A clock with optimal timing is supplied to the A/D converter 7. FIG. 10 shows an example of the determination circuit. In the same figure, 121 is A
The register 122 temporarily holds the data converted by the /D converter 7, and the register 122 holds the largest value from the sequentially input digital data up to that point.
123 is a register that holds a select signal when the data held in register 122 is input; 124 is a comparator that compares the values of registers 121 and 122;
5 is a gate circuit that controls the latch clocks of registers 122 and 123 according to the comparison output of comparator 124; 126;
is a counter for sequentially changing the select signal,
Reference numeral 127 represents a register in which select signal values for reading the ID area and servo area are held, and reference numeral 128 represents a multiplexer that switches between registers 123, 127 and counter 126 to supply a select signal.

In performing the judgment operation, first, the registers 122, 1
．． Reset 23. Next, store the first data in register 1.
21, and this data and the select signal at this time are unconditionally held in registers 122 and 123. When the second data is held in register 121, this data and the data in register 122 are compared by comparator 124. Only when the value of register 121 is greater than the value of register 122, 1# is output as a comparison result, and in other cases, 0# is output. Since the gate circuit 125 passes the latch clock only when the comparison result is 1', the values of registers 122 and 123 are updated, but when the comparison result is 8.
There is no change when it is 0#. When this procedure is repeated to complete the input of all data, the register 123 retains the selection signal when the maximum data was obtained. When reproducing the user area, multiplexer 128 switches from counter 126 to register 123 and outputs a select signal.

Furthermore, when reading out the servo area and ID area, the value of the register 127 is always output as a select signal. Although it is possible to perform this type of judgment processing using a microcomputer, it is not practical because a high-speed microcomputer is required to compare each data input, so it is not practical to hold all data in registers and use a microcomputer. A suitable method is to sequentially read and compare the results using a computer. in this way.

Since the optimum point is found from the relative value of the reproduced signal, it is not affected by the amplitude of the reproduced signal.

Next, FIG. 11 shows an embodiment in which the present invention is applied to a magneto-optical recording type optical disk device. In this case, the pre-pits created in advance on the disk can be reproduced by changing the amount of reflected light in the same way as in the embodiment shown in Figure 1, but unlike the pre-pits, the recorded part can be reproduced using the polarization of the reflected light. It is necessary to detect the rotation angle of a surface. Therefore, a second photodetecting element (included in the optical pickup 3) separate from the pre-pit section and a second preamplifier 4'
is necessary. In the explanation of the embodiment shown in FIG. 1, only the recording position fluctuation during recording was considered as the cause of the need for clock position adjustment, but in the magneto-optical recording method, A delay time difference occurs between the first photodetecting element that reproduces the part and the preamplifier. Conventionally, designs and adjustments were made to match the delay times of both with high accuracy, but by using the present invention, accuracy specifications can be relaxed, and changes due to changes over time can also be accommodated. Therefore, it has a great effect on reducing the cost and improving the reliability of the drive device. In Fig. 11, the output of the preamplifier is set to one A/
Although a method is shown in which the data is input to a D converter, it is also possible to connect a separate A/D converter to each preamplifier, digitize it, and then switch it with a selector. In this case, selector 1 is used for the A/D converter on the magneto-optical reproduction signal side.
The delayed clock selected in step 1 is connected, and 15 recovered clocks obtained from the clock recovery circuit are connected to the A/D converter on the pre-pit side.

In the above explanation, we have been able to describe the rough clock adjustment method when reproducing the data area, but the same idea can also be used to adjust the clock when reproducing the pre-pit area. There is a delay between the peak signal and the peak detection signal due to circuit characteristics.Also, in the clock regeneration circuit, there is a delay time in the regenerated clock 15 due to the data 1~delay.This delay time is calculated as Similarly, the problem can be solved by selecting the optimal clock from multiple delayed clocks.The signal to BriPit 1 is used as the judgment signal.In the case of the sample servo method, a pit for clock synchronization is suitable.However, clock synchronization Since the synchronization signal of the synchronization area is not recorded continuously in the servo pin 1, the optimal clock is determined by changing the read reflock for each servo area.The determined select signal is stored in the register shown in Figure 10. Tarock selection is performed by holding the data at 127. Unlike the data area, the input period of digital data for judgment is long, so direct data comparison by a microcomputer is possible.Also, it is not necessary to constantly make judgments. Instead, it is sufficient to perform the determination when replacing the disk and at regular intervals and retain the determination results.

Also, 1 decision is one decision action, and there is no ↑-j 8 bet.

Regarding the data area, - Judgment number of times: Necessary synchronization signal Δ - For multiple sets, multiple judgments can be made with low values and the average value can be used as the final judgment. As another method, it is also possible to select and successively capture the reading of the playback signal by the tarock a plurality of times, and use the average Xp value as the data read by the tarlock. In either case, the synchronization area increases and the scale of the determination circuit increases, but the reliability of the determination result improves. Regarding the determination of the pre-pit portion, since the servo area is always repeated at a constant period, it is easy to perform a plurality of determination operations, and the number of times the averaging is performed can be arbitrarily set.

〔Effect of the invention〕

According to the present invention, since the reproduced clock position can be set to the optimum position without being affected by the amplitude value of the reproduced signal, there is an effect of reducing the reading error rate.

Furthermore, since delay fluctuations due to circuit adjustment errors and changes over time can be absorbed, the cost of the drive device is reduced and compatibility between disks and drives is improved.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory diagram of sample servo system data, FIG. 3 is an explanatory diagram of a servo area, and FIG. 4 is an explanatory diagram of sectors. FIG. 5 is an explanatory diagram of the operation of the peak detection circuit in FIG. 1,
6 is a block diagram of the PLL in FIG. 1, FIG. 7 is a block diagram of the delay element in FIG. 17, and FIG. 8 is a block diagram of the PLL in FIG.
9 is an explanatory diagram of the determination method, FIG. 10 is a block diagram of the determination circuit in FIG. 1, and FIG. 1.1 is a second implementation according to the present invention. FIG. 2 is an example block diagram. 1... Optical disc, 3... Optical pickup, 4...
・Preamplifier, 5...Peak detection circuit, 6...Clock regeneration circuit, 7...A/D converter, 10...Delay element, 11. Pit for Bitkuo, Ridori 4 ■ Kango Hisu gong. , ri ') O-t 'l '7 C) Rough ri0+,ri Chloraf Glow/2 and 1 2 34
5 Jugang No. 1 Ward Jumu Power

Claims (1)

[Claims] 1. An apparatus for recording and reproducing digital data, comprising: a clock reproducing means for generating a clock signal synchronized with a recording signal based on first specific information recorded on a medium; a delay means for inputting and outputting a plurality of delayed clocks; a selection means for selecting one of the clocks from the plurality of outputs of the delay element and supplying it as a converted clock signal; and an analog reproduced from the medium. an analog-to-digital conversion means for converting a signal into a digital signal; the digital output of the analog-to-digital conversion means is used as an input signal; the selection means is controlled in synchronization with second specific information in the reproduced signal; determination to store a control value of a selection means when obtaining a specific digital signal from the group of digital signals, and to output the stored control value when reproducing a group of information recorded at the same time as the second specific information; A data recording and reproducing device characterized in that it includes means. 2. In claim 1, the control means is controlled in synchronization with the first specific information, and a control value of the selection means is stored when obtaining the specific digital signal from the obtained group of digital signals. . A data recording/reproducing apparatus comprising a second determination circuit that outputs the stored control value when reproducing the first specific information and other information recorded at the same time. 3. The data recording and reproducing apparatus according to claim 1, wherein the recording medium is an optical recording medium in which recording is performed using an optical method or a combination of optical and magnetic methods, and reproduction is performed using an optical method. 4. In claim 1, 2 or 3, the recording medium is disk-shaped, and the first specific information is a clock synchronized pit in prepits containing servo information formed at regular intervals during disk manufacturing. , a synchronization signal of a predetermined pattern to which the second specific information is additionally recorded, and a group of information recorded at the same time as the second specific information is in one sector, which is a storage area unit of an external storage device for a computer. Data recording and reproducing device configured. 5. The data recording and reproducing apparatus according to claim 1, 2, 3, or 4, wherein the determining means has a function of performing a plurality of determining operations and obtaining an average value thereof.