JPH08185632A - Optical disk and optical disk device - Google Patents

Abstract

PURPOSE: To provide an optical disk capable of simultaneously reading out recording information from plural tracks without using a special optical system. CONSTITUTION: A track bundle consisting of plural tracks is formed in a parallel spiral shape, and a track interval d2 between track bundles is formed wider than the track interval d1 in the track bundle. Thus, a tracking shift is detected easily without using the special optical system, and the recording information are read out from plural tracks simultaneously.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disc and an optical disc device, and more particularly to an optical disc in which information related to each other is recorded on a plurality of tracks and an optical disc device for reproducing the same. is there.

[0002]

2. Description of the Related Art Conventionally, in an optical disc device, recorded information is recorded on a track by focusing laser light on one to three tracks out of many tracks formed on an information recording surface. Is used. In the optical disc device, various tracking error detection methods based on this reading method have been established. For example, 3-beam method, push-pull method, DPD (Di
fferential phase detection) method.

[0003]

By the way, in order to further improve the amount of recorded information that can be read at one time with one laser beam, it is one way to read the recorded information from four or more tracks at one time. Although it may be considered as a solution, such an optical disk device has not been put into practical use at present, and accordingly, there is no established method for detecting the tracking error.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose an optical disk and an optical disk device which have a simple structure and can simultaneously read recorded information from more tracks than ever before. It is a thing.

[0005]

In order to solve such a problem, in the optical disk of the present invention, a plurality of tracks (T
The track bundle composed of R _{k1 to} TR _k4 ) is formed in a parallel spiral shape, and the track interval (d2) between the track bundles is formed wider than the track interval (d1) in the track bundle.

Further, in the optical disc of the present invention, a track bundle composed of a plurality of tracks (TR _{k1 to} TR _k4 ) is formed in a parallel spiral shape, and the track interval (d2) between the track bundles is within the track bundle. Of the optical disk (5) formed wider than the track interval (d1) of the optical disk, and the reflected light is imaged on the light receiving element (6), and the light receiving element (6). ) A signal processing unit that generates a tracking error signal based on the difference output of the output signals respectively output from the plurality of light receiving cells (RF1 to RF4, T1, T2) arranged above.

[0007]

Function: Forming a track bundle composed of a plurality of tracks (TR _{k1 to} TR _k4 ) in a parallel spiral shape, and forming a track interval (d2) between the track bundles wider than the track interval (d1) in the track bundle. Thus, a tracking error can be detected without using a special optical system, and recorded information can be simultaneously read from a plurality of tracks.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

(1) Optical Disk In the optical disk of this embodiment, a track bundle (hereinafter, referred to as a band) having four tracks as one unit is formed in a parallel spiral shape. The track arrangement is shown in FIG. FIG. 1 shows an image of the information recording surface of the optical disk formed on the light receiving surface. By the way, the light and shade on the drawing shows the presence or absence of pits, and the bright areas are those without pits.
Dark areas represent areas with pits.

However, in the case of this optical disc, as shown in FIG. 1, the tracks are recorded so that the track interval d2 between the bands is wider than the track interval d1 within the band (that is, d2> d1). The optical disk device described in the following sections is adapted to detect a tracking error by using this difference in the track interval.

(2) Optical Pickup Configuration (2-1) Overall Configuration In this section, the overall configuration of the optical pickup 1 will be described with reference to FIG. The light pickup 1 is composed of a light emitting diode 2 having a predetermined light emitting region and a plurality of optical elements.
The light beam emitted from the light emitting diode 2 passes through the half mirror 3, is then condensed by the objective lens 4, and is irradiated onto the optical disk 5. At this time, the light beam irradiates a predetermined area that straddles a plurality of tracks formed on the optical disk 5.

The reflected light reflected on the surface of the optical disk is condensed via the objective lens 4, and then reflected by the half mirror 3 to form an image on the light receiving surface of the photodetector 6. Light-receiving cells are arranged on the light-receiving surface of the photodetector 6 so as to correspond to the image forming pattern of FIG. 1, that is, so as to match the track pitch of the optical disk 5. Incidentally, the area of the light receiving cell is given by the area obtained by multiplying the light emitting area of the light emitting diode 2 by the lateral magnification n ₁ of the lens package. Further, these light receiving cells are arranged at intervals according to the size of the pit imaged on the photodetector 6 and the track pitch. For example, the size of the pit image focused on the photodetector 6 is the size of the pit size of the optical disk multiplied by the magnification n _{2 of the} objective lens. The light receiving cell is arranged at the same pitch d1 as the track pitch formed on the light receiving surface.

The light detection signals detected by these light receiving cells are individually supplied to the tracking error detection circuit section 7 and processed there. That is, the tracking error detection circuit section 7 outputs the input photodetection signal from the output terminal through signal processing such as adding or weighting each track as it is, and then adding. Here, from the first output terminal, the information signal (R
F signal) is output, the tracking error signal is output from the second output terminal, and the focus error signal is output from the third output terminal. The detailed internal structure of the tracking error detection circuit section 7 will be described in the next section.

(2-2) Configuration of Tracking Error Detection Circuit Unit FIG. 3 shows the configuration of the tracking error detection circuit unit 7.
Here, the light receiving cells RF1 to RF4 are for RF detection used to detect the light-dark pattern of each track as an RF signal. Further, the light receiving cells T1 and T2 arranged at both ends thereof are for detecting a tracking error. The tracking error detection circuit section 7 is adapted to input the RF signals output from the light receiving cells RF1 to RF4 to the RF amplifier 7A for amplification. RF amplified by RF amplifier 7A
The signal is demodulated by the digital signal processing circuit 7B, supplied to the output controller 7C, and stored in the memory 7D.

The digital information signal output from the output controller 7C is also supplied to the signal processing circuit 7E for digital / analog conversion, and then output as an analog information signal (audio signal, video signal, etc.) from the output terminal. Further, the light receiving cells T1 and T2 and the light receiving cells RF1 to R
The output from F4 is taken into the signal processing circuit 7F, and a tracking error is detected based on the detection principle described in the next section. The detection result is fetched into the servo circuit 7G as a tracking error signal and output as a tracking error signal and a focus error signal.

(3) Principle of Tracking Error Detection Finally, the principle of tracking error detection by the signal processing circuit 7F will be described. The signal processing circuit 7F is a light receiving cell RF1.
~ Tracking deviation can be detected based on 6 RF signals input from RF4 and T1 and T2. Next, the distribution of the output level output from each light receiving cell when there is a deviation from the output level output from each light receiving cell during tracking is shown.

First, FIG. 4 (A) shows the intensity distribution of each light receiving cell when tracking is correct. In this state, the output levels of the light receiving cells T1 and T2 provided for detecting the tracking error become equal. 4 (B) to FIG. 4 show how the tracking shifts from this state.
(G).

Of these, FIG. 4 (B), FIG. 4 (D), and FIG.
In the state (E), since the intensity distributions of the output levels output from the light receiving cells T1 and T2 are different, a tracking error can be detected. On the other hand, FIG.
In the states of (F) and FIG. 4 (G), the tracking is shifted, but the output levels of the light receiving cells T1 and T2 are equal. However, even in this case, for example, as shown in the state of FIG.
Since only the light receiving cell RF4 is located on the gap between the bands, the intensity is higher than that of other RF light receiving cells.
The same applies to the cases of FIG. 4 (F) and FIG. 4 (G), and the intensity of one light receiving cell is always high.

When the tracking is deviated as described above, a light receiving cell having a high intensity can be obtained only on the gap between the bands. Therefore, when the output levels of the light receiving cells T1 and T2 are equal, the light receiving cells RF1 to RF for RF signal detection are detected.
It is possible to detect the direction and amount of tracking deviation by detecting the light receiving cell having the highest intensity among the four.

As a result, it is possible to realize an optical disk device capable of simultaneously reading recorded information from four tracks. Further, since no special optical system is required for detecting the tracking error, it is possible to realize the downsizing and cost reduction of the optical pickup.

(4) Other Embodiments In the above-mentioned embodiments, the case where the record information is read out from four tracks at the same time has been described. Can also be applied when reading Also in this case, when a plurality of tracks to be read simultaneously are set as one band, the interval between the tracks may be wider than the interval between the tracks within the band.

[0022]

As described above, according to the present invention, the track bundle composed of a plurality of tracks is formed in the parallel spiral shape, and the track interval between the track bundles is formed wider than the track interval within the track bundle. It is possible to easily obtain an optical disk capable of simultaneously reading recorded information from a plurality of tracks without using a special optical system. Further, it is possible to obtain an optical disk device which does not need to use a special optical system for simultaneously reading recorded information from a plurality of tracks.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a track pattern formed on a light receiving surface of a photodetector.

FIG. 2 is a schematic diagram showing the structure of an optical pickup.

FIG. 3 is a block diagram showing a configuration of a tracking error detection circuit section.

FIG. 4 is a schematic diagram showing a distribution relationship between a tracking shift and an output level output from each light receiving cell.

[Explanation of symbols]

1 ... Optical pickup, 2 ... Light emitting diode, 3 ...
Half mirror, 4 ... Objective lens, 5 ... Optical disk,
6 ... Photodetector, 7 ... Tracking error detection circuit section.

Claims (4)

[Claims] 1. A light beam, characterized in that a track bundle composed of a plurality of tracks is formed in a parallel spiral shape, and a track interval between the track bundles is formed wider than a track interval within the track bundles. Disk. 2. The optical disc according to claim 1, wherein information relating to each other is recorded on the plurality of tracks forming the track bundle. 3. A track bundle composed of a plurality of tracks is formed in a parallel spiral shape, and a track interval between the track bundles is larger than a track interval within the track bundle in a predetermined area of the optical disk. Irradiate,
An optical pick-up unit that forms an image of the reflected light on the light receiving element, and a signal processing unit that generates a tracking error signal based on the difference output of the output signals respectively output from the plurality of light receiving cells lined up on the light receiving element. An optical disk device characterized by comprising: 4. The optical disc according to claim 3, wherein the plurality of light receiving cells are arranged at the same pitch as the track pitch in the track bundle formed on the light receiving surface of the light receiving element. apparatus.