JPH0366073A - Optical disk driver - Google Patents

Abstract

PURPOSE:To attain the signal processing in real time with simple circuit constitution by providing a phase shift circuit taking bit synchronization and a synchronization pattern delay circuit taking byte synchronization to a signal processing section. CONSTITUTION:An output signal of a photodetecting element 17b is binarized by binarizing circuit 31b, inputted to a phase shift circuit 34, retarded by a set delay and signals having a phase deviation of nearly one clock are synchro nized. A signal read from a 2nd channel track synchronously in terms of bits with a ch1 data from a reference 1st channel track is inputted to a synchroniza tion pattern detection circuit 32b, the detected synchronization pattern signal is inputted to a synchronization pattern delay circuit 35b, where the signal is completely synchronized with the ch1 data and a ch2 data is read. A readout signal from other channel track detected by other photodetecting element (-17) is synchronized similarly with the ch1 data and real time signal processing is always attained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a so-called multi-beam type optical disk drive device.

[Conventional technology]

Conventionally, for example, Optical Memory Symposium Proceedings pp, i
To obtain a high bit rate, as described in ``Magneto-Optical Disk Memory for Movies''.

2. Description of the Related Art Optical disk drives are known that record/reproduce mutually related data by dividing it into a plurality of tracks arranged on an optical disk.

On the other hand, in order to improve the data transfer speed, for example, as described in Proceedings of the Spring 1988 Japan Society of Applied Physics Conference, 28a-ZQ-24, multiple optical spots are individually placed on multiple tracks arranged on an optical disk. A multi-beam optical head has been proposed in which each track is used as an independent channel for recording, reproducing, or erasing signals.

In such a multi-beam optical disk drive device, unless the optical spots are perfectly aligned in the radial direction of the optical disk, the signals read from each track cannot be synchronized, and the real-time In particular, MCAV (Modified
Con5tant Angular Velocit,
In optical discs such as y) type optical discs, where the recording density of signals increases toward the outer tracks, even if the circumferential position of the optical spot differs slightly, the time difference between the signals read from the outer tracks is large. This makes real-time signal processing even more difficult.

However, since the light spot focused on the optical disk varies due to variations in the distance between the emission apertures of the laser array and the lens focal length, it is impossible to perfectly align the multiple light spots in the radial direction of the optical disk. It is actually difficult. Therefore, in order to process the signals read from the multi-beam optical head in real time, some kind of processing circuit is required.

Conventionally, real-time signal processing has been realized by providing a signal processing section with a memory and a drive circuit for the memory.

[Problem to be solved by the invention]

However, such a configuration requires a large capacity memory and a complicated memory drive circuit, resulting in a problem that the multi-beam type optical disk drive device becomes expensive.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and its purpose is to provide an optical disk drive device that is inexpensive and capable of real-time signal processing.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention provides an optical disk in which a plurality of light spots are individually focused on a plurality of tracks arranged on an optical disk, and each track is used as an independent channel for recording, reproducing, or erasing signals. In the drive device,
The signal processing section includes a phase shift circuit that extracts the clock of a reference channel track and synchronizes signals read from other channel tracks using this clock as a reference, and a synchronization pattern signal recorded for each channel track. and a synchronization pattern delay circuit for synchronizing the synchronization pattern signal detected from the reference channel track with the synchronization pattern signal detected from other channel tracks.

[Effect]

The phase shift circuit synchronizes signals read from other channel tracks using the clock of the reference channel track as a reference, so it can synchronize signals that have a phase shift of about one clock, that is, bit synchronize. be able to.

On the other hand, the synchronization pattern delay circuit detects the synchronization pattern recorded for each channel track and synchronizes the synchronization pattern signal detected from the reference channel track with the synchronization pattern signal detected from other channel tracks. Therefore, signals having a phase shift of one clock or more can be synchronized, that is, byte synchronization can be achieved.

Therefore, regardless of the circumferential deviation of the optical spot and the radial position of the track to which the optical spot is irradiated, the signals read from each channel track can always be synchronized and real-time signal processing can be performed. can. Also.

Since a large capacity memory and a complicated circuit for driving it are not required, this type of optical disk drive device can be implemented at low cost.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an optical disk drive device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram of the optical disk drive device according to the present embodiment, FIG. 2 is a plan view of main parts of the optical disk showing the multi-beam irradiation state, FIG. 3 is a block diagram of the synchronization circuit, and FIG.
The figure is a block diagram showing an example of a phase shift circuit, and FIG. 5 is a block diagram showing an example of a synchronous pattern delay circuit.

As shown in FIG. 1, the optical disc drive device of this embodiment mainly synchronizes an optical head 2 capable of focusing a plurality of light spots on an optical disc l and signals detected by this optical head 2. It consists of a synchronization circuit 3.

As shown in this figure, the optical head 2 emits a plurality of light beams 11.
a laser array 12 capable of emitting a to lln, a collimator lens 13, a beam splitter 14, an objective lens 15 that focuses the parallel light beam from the beam splitter 14 onto the signal surface 1a of the optical disc 1, and an optical disc ln. and a focusing lens 18 that narrows down the reflected light 16a to 16n from the split photodetector 17 and focuses it onto each of the photodetecting elements 17a to 17e constituting the split type photodetector 17.

As shown in FIG. 2, the optical disk 1 has a large number of tracks 21a, 21b, 21c in the radial direction.

... are defined, each track 21a, 21b.

21c, . . . have a plurality of sectors 22a in the circumferential direction.

It is divided into 22b, 22c, . Each sector 22a, 22b, 22c,... is a servo area 23
and a data area 24 following this. In the servo area 23, at least a synchronization bit and an address bit (not shown) are formed.

A plurality of light spots focused on the optical disk 1 by the optical head 2 are designated by reference numerals 25a to 25 in FIG.
Adjacent tracks are focused one by one as indicated by n. Each of the optical spots 25a to 25n is adjusted to be aligned in a straight line along the radial line XX of the optical disc 1.

For example, this may be due to variations in the emission aperture of the laser array 12 or variations in the focal length of the objective lens 15.

In reality, as shown in the figure, the light is focused with some variation in the circumferential direction.

Note that the emitted light 11a''ll from the laser array 12
n can be independently modulated, making it possible to perform signal processing using each track as an independent channel.

The synchronization circuit 3, as shown in FIG.
Binarization circuits 31a~ connected to the output terminals of 7a"17n
31n and synchronization pattern detection circuits 32a to 32n,
One photodetection element arbitrarily selected from the plurality of photodetection elements 17a to 17n.

In this example, the clock extraction circuit 33 provided in the signal processing section following the photodetector 17a and the other photodetectors 17b to 1
Phase shift circuit 34 provided in the signal processing section following 7n
b to 34n and synchronous pattern delay circuits 35b to 35n
It consists of

A pattern matching circuit or the like can be used as the synchronization pattern detection circuits 32a to 32n.

The clock extraction circuit 33 may be one that extracts a clock by pattern matching, or one that extracts a clock using pattern matching.
From 6 onwards, a phase-locked loop circuit (PLL circuit) generates a clock, generates a clock bit detection gate signal, and extracts the clock bit.Furthermore, it is not a clock bit signal itself, but a gate generated in a PLL circuit. It is possible to use a device that extracts a clock using a signal. Of these, the latter two have the advantage of preventing erroneous detection due to defects on the optical disk surface.

The phase shift circuits 34b to 34n, as shown in FIG. A phase comparison circuit 37 that performs phase comparison with a clock extracted from a reference channel track by the photodetection element 17a and feedback-controls the variable delay element 34 using the output signal, and a low-pass circuit provided in this feedback circuit. It is composed of a filter 38.

On the other hand, the synchronization pattern delay circuits 35b to 35n, as shown in FIG. It is comprised of a counter 40 that detects the time difference between pattern signals, and a selector 41 that delays the synchronization pattern signal registered in the shift register 39 based on the output signal of the counter 40.

The operation of the optical disk drive device according to the embodiment will be explained below.

A plurality of light beams 11a to 11l emitted from the laser array 12
ln is collimated by the collimator lens 13, the optical path is changed by the beam splitter 14, and then the objective lens 15 separates each track 21a of the optical disk 1.
, 2 l b, 21 c.

...The light is focused upwards.

Reflected light beams 16a to 16ni from the optical disk 1; 1 objective lens 15. Beam splitter 14, aperture lens 1
8 and is individually focused on each of the photodetecting elements 17a to 17n constituting the split type photodetector 7.

The output signal from the photodetecting element 17a is binarized by a binarization circuit 31a, and a clock extraction circuit 33 extracts a clock from the binarized data. Thereafter, the binarized data and the clock are synchronized by the synchronization pattern detection circuit 32a, and the signal (ch 1 data) from the first channel track 21a, which serves as a reference, is read out.

The output signal from the photodetection element 17b is binarized by the binarization circuit 31b, and then input to the phase shift circuit 34b, where it is delayed by the amount of delay set in the variable delay element 36. The amount of delay of the variable delay element 36 is determined by calculating the phase difference between the output signal from the variable delay element 36 and the clock using a phase comparator circuit 37.
It is set by detecting the output signal and feeding back the output signal to the variable delay element 36 through the low-pass filter 38. This makes it possible to synchronize signals having a phase shift of about one clock, that is, to synchronize bits.

The read signal from the second channel track 21b, which has been bit synchronized with the chi data by the phase shift circuit 34b, is input to the synchronization pattern detection circuit 32b, and a synchronization pattern signal is detected.

The synchronization pattern signal detected by the synchronization pattern detection circuit 32b is input to the synchronization pattern delay circuit 35b, and is synchronized with the synchronization pattern signal read from the reference channel track 21a. As a result, ch2 data that is completely synchronized with chi data is read out.

The read signals from other channel tracks detected by other photodetecting elements (~17n) are also synchronized with the chi data in the same manner.

As described above, the optical disk drive device of the above embodiment is equipped with a phase shift circuit for correcting a phase shift of about one clock in the signal processing section, and a synchronization pattern delay circuit for correcting a phase shift of one clock or more. Regardless of the circumferential deviation of the light spot or the radial position of the track illuminated by the light spot, the signals read from each channel track can always be synchronized and real-time signal processing can be performed. . Furthermore, since a large-capacity memory and a complicated circuit for driving it are not required, this type of optical disk drive device can be implemented at low cost.

Note that the configurations of the phase shift circuit and the synchronization pattern delay circuit are not limited to those listed in the above embodiments, and any configurations can be used as long as they have similar functions.

Others 1. For example, parts other than the essential parts of the present invention, such as the configuration of the optical head and the preformat pattern of the optical disc, may be modified as appropriate without departing from the spirit of the present invention.

〔Effect of the invention〕

As explained above, the optical disk drive device of the present invention has the following features:
The signal processing unit is equipped with a phase shift circuit that corrects a phase shift of about 1 clock, and a synchronization pattern delay circuit that corrects a phase shift of 1 clock or more. Regardless of the radial position of the irradiated track, the signals read out from each channel track can always be synchronized, and real-time signal processing can be performed at low cost.

[Brief explanation of drawings]

All the figures are for explaining one embodiment of the present invention, and FIG. 1 is a schematic configuration diagram of an optical disk drive device, and FIG.
Fig. 3 is a block diagram of the synchronization circuit, Fig. 4 is a block diagram of an example of the phase shift circuit, and Fig. 5 is a block diagram of the synchronization pattern delay circuit. FIG. 2 is a block diagram showing an example. DESCRIPTION OF SYMBOLS 1... Optical disc, 2... Optical head, 3... Synchronization circuit, 21a, 21b, 21c
, ......Truck, 25a~25n...
...Light spot, 31a to 31n...Binarization circuit, 32a to 32n...Synchronization pattern detection circuit, 33...Clock extraction circuit 33.34b
~34n... Phase shift circuit. 35b to 35n...Synchronization pattern delay circuit. Figure 1 0 Figure 2 Figure 3 506-

Claims (3)

[Claims] (1) In an optical disk drive device that individually focuses multiple light spots on multiple tracks arranged on an optical disk and processes signals such as recording, reproducing, or erasing signals using each track as an independent channel, the signal processing section , a phase shift circuit that extracts a clock of a reference channel track and synchronizes signals read from other channel tracks using this clock as a reference, and detects a synchronization pattern signal recorded for each channel track; An optical disc drive apparatus comprising: a synchronization pattern delay circuit that synchronizes a synchronization pattern signal detected from the reference channel track with synchronization pattern signals detected from other channel tracks. (2) The phase shift circuit according to claim 1,
The variable delay element that delays the binarized data read from the other channel track and the output signal of this variable delay element and the clock extracted from the reference channel track are compared, and the output thereof is An optical disk drive device comprising a phase comparator circuit that feedback-controls the delay amount of the variable delay element using a signal. (3) In claim 1, the synchronization pattern delay circuit includes a shift register that registers a synchronization pattern signal detected from the other channel track, a synchronization pattern signal detected from the reference channel track, and a shift register that registers the synchronization pattern signal detected from the other channel track. The present invention is characterized by comprising a counter that detects a time difference between synchronization pattern signals read from other channel tracks, and a selector that delays the synchronization pattern signal registered in the shift register based on the output signal of the counter. optical disk drive device.