JPH03192582A - Information recording disk storing pilot signal for tracking and its player - Google Patents

Abstract

PURPOSE:To ensure tracking servo by using a pilot signal track and providing 1st and 2nd tracks with 1st and 2nd information signals recorded thereon at both sides of the pilot signal track with a same track pitch. CONSTITUTION:First and 2nd information track TA, TB are provided at both sides of a pilot signal track Tp. Each output from photoelectric conversion elements 21,22 based on a couple of subbeam spots SA,SB is fed to RF amplifiers 23,24 and also fed to BPFs 25, 26. A pilot signal component passing respectively through the BPFs 25, 26 is subject to amplitude detection by amplitude detection circuits 27, 28. A difference between outputs of the circuits 27, 28, that is, the difference between the amplitudes of the pilot signal component included in each read signal based on the beam spots SA,SB is taken at a differential amplifier 29 and the difference signal is outputted as a tracking error signal TE. The position control is implemented by applying tracking servo based on the signal TE.

Description

TECHNICAL FIELD The present invention relates to an information recording disc that carries a tracking pilot signal and a performance device thereof, and more particularly to a tracking error signal generation circuit in an information recording disc performance device.

Background Art For example, in an optical disc player that plays information recording discs (hereinafter simply referred to as discs) such as video discs and digital audio discs, a laser beam spot as a spot for reading recorded information of a pickup is placed on the eccentricity of the disc. Regardless, a tracking servo device is essential to accurately follow the recording track. In this tracking servo device, for example, a main beam spot for reading recorded information and a pair of sub-beam spots for detecting tracking information that precede and follow each other when the main beam spot moves relative to the disk in the rotational direction are used. These beam spots are arranged so that the line connecting their tip axes has a predetermined offset angle with respect to the track tangential direction, and the low-frequency components of detection outputs A and B based on the pair of sub-beam spots are A generation circuit using a so-called three-beam method is used to generate the tracking error signal TE from the difference (A-B) of the amplitude of the RF acid component (or the amplitude of the RF acid component).

Incidentally, in recent years, the density of recorded information on disks has been increasing, and as the recording density increases, the pitch of recording tracks inevitably becomes narrower. When the track pitch becomes narrower, conventional tracking error signal generation circuits cannot generate a sufficient tracking error signal because the contrast between light and dark (or the amplitude change of the RF acid component) cannot be maintained when the beam spot crosses the track. It will not be possible to do this reliably. FIG. 6 shows the waveforms of the RF multiplied signal a), the detection outputs A and B(b) based on a pair of sub-beam spots, and the tracking error signal TH when the track pitch is large. The waveforms of the RF multiplied signal a) when the pitch is small, the detection outputs A and B based on a pair of sub-beam spots (b), and the tracking error signal TE are shown, respectively.

SUMMARY OF THE INVENTION [Object of the Invention] Accordingly, an object of the present invention is to provide an information recording disk and a performance device thereof, which can perform tracking servo reliably even when the track pitch is small.

[Structure of the Invention] An information recording disk performance device according to the present invention includes a pilot signal track in which a tracking pilot signal of a predetermined frequency is recorded, and a first and a first and second tracks having the same track pitch on both sides of the pilot signal track. An information recording disc performance device having first and second information signal tracks on which two information signals are recorded,
information reading means including a pair of information reading spots that read recorded information on the first and second information signal tracks while leading and following each other during relative movement in the rotational direction with the information recording disk; and the pair of information reading spots. The apparatus is configured to include tracking error signal generating means for deriving a difference in amplitude of the pilot signal components included in each of a pair of read outputs based on the reading spot as a tracking error signal.

[Operation of the Invention] In the information recording disk performance device according to the present invention,
When playing an information recording disc that has a pilot signal track for tracking and first and second information signal tracks located on both sides of the pilot signal track with the same track pitch, the information recording disc moves ahead of and away from each other when moving relative to the disc in the rotational direction. The recording information of the first and second information signal tracks is read by the subsequent pair of information reading spots, and the amplitude of the pilot signal component included in each of the pair of read outputs based on the -pair of information reading spots. The difference between the two is derived as a tracking error signal.

Example Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a block diagram showing an example of a disk recording system to which the present invention is applied. In the figure, reference numeral 1 denotes a master disk, which is rotationally driven by a motor 2. As shown in FIG.

On this master disk 1, the first and second information signals are recorded as separate information signal tracks, and a tracking pilot signal is recorded as a pilot signal track so as to be located in the middle between the image information signal tracks. be done. As the first and second information signals, for example, completely separate signals may be used, or one signal may be divided into two channels and used.

The first and second information signals are each modulated by an FM modulator 3.4, amplitude limited by limiter circuits 5, 6, and then supplied to optical modulators 7, 8. On the other hand, an oscillator 9 that generates a tracking pilot signal of a predetermined frequency fP is provided, and the pilot signal fP generated from the oscillator 9 is amplitude-limited by a limiter circuit 10 and then supplied to an optical modulator 11 . The optical modulators 7, 8, and 10 expose three laser beams emitted from a laser light source 12 by irradiating the photoresist surface of the disk master 1 as beam spots while turning them on and off according to modulation signals. At this time, the recording optical system is set so that the distance d1 between beam spots for information recording, that is, the track pitch, is, for example, 0.8 μm.

As a result, pits (exposed portions) representing recording information are spirally recorded on the disk master 1 as three recording tracks (pit rows), and a master disk (recording master) is formed by development processing. As shown in FIG. 2, the disc obtained from this master disc includes a pilot signal track Tp on which a tracking pilot signal of a predetermined frequency fP is recorded, and a pilot signal track Tp on which a tracking pilot signal of a predetermined frequency fP is recorded.
With respect to the first track with the same track pitch on both sides.
The first information signal is recorded with the second information signal. The second information signal track T A + T B will be recorded in a spiral manner. FIG. 3 shows the positional relationship of each track. For example, the track pitch of the pilot signal track Tp is 1.6 μm1, and the information signal tracks "rA" on both sides of the pilot signal track Tp are 1.6 μm.
, "re" track pitch is 0.8 μm.

Next, an embodiment of a performance apparatus for a disc recorded in this manner will be explained based on the block diagram of FIG. 4.

First, a pickup (not shown) as an information reading means used in this musical performance device focuses a laser beam on three beam spots, namely, a main beam spot SM and a main beam spot SM.
A pair of sub-beam spots sA that precede and follow, respectively, when moving relative to the disk in the rotational direction.
, Ss are irradiated onto the recording track of the disk such that the line connecting their leading axes has a predetermined positional relationship with respect to the tangential direction of the track, and these beam spots SA, S
The structure is such that a built-in photoelectric conversion element receives reflected light from the disk surface based on B and sM. This configuration is
This is exactly the same as the three-beam method used in current disc performance devices, and a so-called four-split photodetector is used as a photoelectric conversion element that receives reflected light from the disc surface based on the main beam spot sM.

In this embodiment, the pair of sub-beam spots SA and SB are arranged in the disk radial direction (track orthogonal direction).
By setting the interval at equal to the track pitch of the information signal track T A + T B, the pair of sub-beam spots SA and ss can be used for both recording information reading and tracking information detection, and the main beam spot SM can be used to eliminate astigmatism. This method is used to detect focus information based on the law. Note that the S/N can be improved by increasing the light intensity ratio of the main beam and the sub-beam as much as possible for the sub-beam.

In FIG. 4, a pair of sub-beam spots SA, S8
The outputs of the photoelectric conversion elements 21 and 22 based on
It is supplied to the F signal processing system and also to BPF (band pass filter) 25 and 26. In the subsequent RF signal processing system, the first and second signals recorded on the disk are
Processing is performed according to the type of information signal. B P
F25°26 each has a passband corresponding to the frequency fP of the tracking pilot signal. BPF2
The amplitudes of the pilot signal components that have passed through the respective pilot signal components 5.26 and 27.26 are detected by amplitude detection circuits 27.28.

Then, in the differential amplifier 29, the amplitude detection circuit 27.2
8, that is, the sub beam spot SA,s
The difference between the amplitudes of pilot signal components included in each read signal based on s is taken, and this difference signal is output as a tracking error signal TE.

Next, the circuit operation of such a configuration will be explained with reference to the waveform diagram of FIG. 5.

When a pair of sub-beam spots SA and Ss cross the recording track while moving at a constant speed in the disk radial direction,
With respect to the recording track that traverses, the read RF multiplied signal which is the output of the photoelectric conversion elements 21 and 22 based on the pair of sub-beam spots SA and ss changes as shown in FIGS. 5(A) and 5(B), and the amplitude detection circuit 27. The amplitude of the pilot signal component included in each read RF multiplied signal which is the output of 28 is the fifth
It changes as shown in Figures (C) and (D). As a result, a tracking error signal TE as shown in FIG. 5(E) is obtained as the output of the differential amplifier 29.

Then, by performing tracking servo based on the tracking error signal TE obtained in this way, the difference in amplitude of the pilot signal components included in the read RF multiplied signal based on the pair of sub-beam spots SA and SB becomes zero. Then, the position of each beam spot in the direction perpendicular to the track (radial direction of the disk) is controlled.

As a result, since the output of each BPF is not affected by anything other than the pilot signal portion, it is possible to generate a tracking error signal TE that allows reliable tracking servo even if the track pitch becomes narrow. In addition, since it uses BPF output, it is less susceptible to noise in other frequency bands.Furthermore, since the optical system is the same as the conventional configuration, it can be easily replaced with the conventional tracking error signal generation circuit. By creating a configuration that allows this, it will also be possible to support normal disks.

As described in detail, the information recording disk performance device according to the present invention includes a pilot signal track for tracking and first and second information signal tracks located on both sides of the pilot signal track with the same track pitch. When playing a disc having the following information, the recorded information of the first and second information signal tracks is read by a pair of information reading spots, and the difference in amplitude of the pilot signal components included in each of the read outputs is used as a tracking error signal. Since the pilot signal track is derived, tracking servo can be performed reliably even when the track pitch is small due to the presence of the pilot signal track.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a disk recording system to which the present invention is applied, FIG. 2 is a diagram showing the positional relationship of each recording track on a disk recorded by such a recording system, and FIG. 4 is a block diagram showing an embodiment of the present invention, FIG. 5 is a diagram of each signal waveform for the recording track to explain the circuit operation of FIG. 4, and FIG.
The figure shows the RF multiplied signal a) when the track pitch is large,
- detection outputs A, B based on paired sub-beam spots;
(b) and each waveform diagram of the tracking error signal TE, FIG. 7 is the RF multiplied signal a) when the track pitch is small,
Detection outputs A, B (
b) and each waveform diagram of the tracking error signal TE. Explanation of symbols of main parts 21.22...Charging conversion element 25.26...Band pass filter 27.28
......Amplitude detection circuit 29...Differential amplifier

Claims (2)

[Claims] (1) A pilot signal track on which a tracking pilot signal of a predetermined frequency is recorded, and first and second information signals on both sides of the pilot signal track on which first and second information signals are recorded with the same track pitch.
An information recording disc characterized in that it has an information signal track. (2) A pilot signal track on which a tracking pilot signal of a predetermined frequency is recorded, and first and second information signals on both sides of the pilot signal track on which first and second information signals are recorded with the same track pitch.
A performance device for an information recording disk having an information signal track, wherein the information recorded on the first and second information signal tracks is read while leading and following each other during relative movement in the rotational direction with the information recording disk. information reading means including a pair of information reading spots; and tracking error signal generation for deriving, as a tracking error signal, the difference in amplitude of the pilot signal components included in each of the pair of read outputs based on the pair of information reading spots. 1. A performance device for an information recording disc, comprising: means.