JPH0346137A - Optical disk - Google Patents

Abstract

PURPOSE:To improve the accuracy of a reference signal by arranging plural pregrooves radially in a radial direction at an equal angle for obtaining the reference signal. CONSTITUTION:Plural pregrooves 6-9 are arranged at an equal angle in the radial direction of an optical disk 1. These pregrooves 6-9 are formed from patterns obtained by feeding, exposing and developing a glass resist panel for prebit at constant speed in the radial direction. Thus, the linearity of the pregrooves 6-9 is higher than that of the prebit and the reference signal with high accuracy can be easily obtained. Thus, the pregrooves in a recording area 3 replaces a bit train, which is radially extended, and the reference clock of sample servo can be generated with high accuracy. In non-recording areas 2 and 4, bits can be arranged according to a sample servo format and accuracy for positioning a clock bit can be evaluated with the pregrooves as a reference. Thus, the accuracy of the reference signal is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical disc for optically recording and reproducing information.

[Prior art] One of the control methods for optical discs is the sample servo method ([
) 13F (discrete block format). This method provides wobble pits on the optical disc that are placed 14 tracks apart from the top of the track, and detects these wobble pits during recording and playback. Sample-hold (S/H)
This is a control method that obtains a tracking signal by holding the signal in a circuit. When using this method, it is necessary to have glock pits arranged at equal intervals on the circumference, so in conventional optical recording and reproducing systems that adopt the CAV (constant angular velocity) method, the clock Pits were previously formed as pre-pits radially in the recording area of the optical disk. In the figure, 61 is an optical disc, 62, 64 is a non-recording area, 63 is a recording area, 6
5 is a disk mounting hole, and 66 is a clock bit string (pre-pit string).

[Problem to be solved by the invention]

However, the optical disc of the above system has the following problems.

In the above-mentioned optical disc, the optical recording and reproducing system operates based on the signal obtained from the clock bits, so high precision is required for the alignment of the clock pits. Conventionally, however, the clock pits are formed by pulses synchronized with a synchronizing signal, but the accuracy is not sufficient due to the wow and flutter of the rotating motor, and the radially radial pre-pit rows meander.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art and provide an optical disc that can obtain a reference signal (clock) with high precision.

[Means to solve the problem]

To achieve the above object, according to the present invention, in an optical disk that stores information in a state where information signals can be optically written and read, a plurality of pregrooves for obtaining a reference signal are arranged radially at equal angles in the radial direction. Provided is an optical disc characterized in that:

[Effect]

By using the pre-groove to obtain the reference signal, the linearity is higher than that of the pre-pit, and the reference signal can be obtained with high accuracy.

〔Example〕 The present invention will be explained in detail below using examples.

FIG. 1 is a plan view schematically showing an optical disc according to the present invention. In the figure, 1 is an optical disc, 2 and 4 are non-recording areas, 3 is a recording area, 5 is a mounting hole for mounting a disk, and 6, 7° and 8.9 are These are a plurality of pregrooves formed to obtain a reference signal. In this example, a case will be described in which four pre-grooves numbered 6 to 9 are provided, but this is merely to simplify the explanation, and any number of pre-grooves may be provided. A plurality of pregrooves 6 to 9 are arranged in the radial direction of the optical disc l,
arranged at equal angles. The pre-grooves 6-9 can be formed from a pattern obtained by exposing and developing a glass resist disk for forming pre-pits, which is fed at a constant speed in the radial direction. Therefore, the linearity of the pregrooves 6 to 9 is considerably higher than that of the prepits, and a highly accurate reference signal can be easily obtained.

In the above example, the pregroove 6-9 is placed in both recording and non-recording areas, but according to the present invention, the pregroove can also be placed only in the recording area or only in the non-recording area. When placed in the recording area, it replaces a radially extending bit string, making it possible to generate a sample servo reference clock with high precision. Furthermore, when placed in a non-recording area, the bits can be placed in the recording area according to the same sample servo format as in the past: it is possible to evaluate the positional accuracy of conventional clock bits based on the pre-probe.

Next, an apparatus configuration for performing signal detection using the optical disc shown in FIG. 1 will be described with reference to FIG. 2.

In FIG. 2, as the optical disc 1 is rotated by the motor 11, the pickup (1)+2 detects the optical signal (J, which is the same as the RF multiplied signal) from the pre-grooves 6 to 9 (FIG. 1) of the optical disc 1. A reference clock signal is generated by the amplifier 13 and the binarization circuit 14, and a pulse synchronized with the RF multiplied signal is generated through the PLL circuit 15.
6 generates a desired timing signal and sends it to a sample-and-hold (S/H) circuit 17 and a window circuit 18. By changing the timing pulse circuit 16,
It is possible to extract bits at arbitrary positions. On the other hand, the pickup (2) 19 is for tracking servo, and in combination with the amplifier 20, generates an optical signal (RF multiplied signal) like the pickup (1) 12.This RF multiplied signal sample-hold circuit The signal sent to I7 and the window circuit 18 and passed through the sample-hold circuit 17 becomes a tracking signal based on a sample servo system (DBF), and the signal sent through the window circuit 18 becomes an arbitrary extracted RF.

Here, the sample servo (particularly the tracking servo) will be explained using FIGS. 3 to 5.

Pre-pit rows extending radially in the radial direction (in the pre-pit rows, in addition to Glock bits, wobble bits for tracking servo are arranged 114 tracks apart from the top of the track, as shown in Figures 4 and 5. .)
When the optical disc 30 with the RF signal is rotated and the RF multiplied signal is detected by the pickup 32 and the amplifier 33, the RF multiplied signal corresponding to the bits as shown in FIG. 5 is obtained. The signal from the clock bit is binarized by a binary value circuit 34, and a timing signal obtained from a PLL circuit 35 and a timing pulse circuit 36 is supplied to a sample-hold circuit 37. The sample-hold circuit 37 configured as shown in FIG.
Sample the recorded RF signal! Racerhard and tracking 1
3, the pickup 32 will move to the truck E.
, the magnitude of the RF multiplied signal by the two wobble bits is the same and the tracking signal is zero. When the pickup shifts in either direction, the magnitude of pF/1 due to the two wobble bits changes, so a tracking signal corresponding to the shift of the pickup 12 can be obtained. Using this signal -C sampler-
If tracking servo is performed, the pickup can be made to follow the track (even if there is eccentricity of the disk, I/rack waviness, etc.).

〔Effect of the invention〕

As explained in detail above, according to the present invention, the pregrooves are arranged radially at equal angles, and the grooves are arranged radially at equal angles.
Since the linearity of the no-group is much higher than that of radially arranging bit strings, it becomes possible to generate an ideal reference clock easily and with high precision.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing the configuration of an optical disk according to the present invention, FIG. 2 is a circuit diagram showing the configuration of a drive device for the optical disk in FIG. 1, and FIG. 3 is a circuit diagram for explaining a sample servo. Fig. 4 is a circuit diagram of the part related to tracking signal generation in Fig. 3, Fig. 5 is a diagram showing the relationship between pre-pits, RF double signal and timing signal, and Fig. 6 schematically shows the configuration of a conventional optical disc. FIG.

Claims (1)

[Claims] (1) An optical disk that stores information in a state where information signals can be written and read optically, characterized in that a plurality of pregrooves for obtaining a reference signal are arranged radially at equal angles in the radial direction. optical disk.