JPS60177448A - Disk for signal adjusting - Google Patents

Abstract

PURPOSE:To obtain a disk that can make the difference of intensity of diffracted light zero only when three diffracted lights are on one track, by obtaining the disk whose track intervals are recorded with information. CONSTITUTION:Information is recorded on a spiral track 15 of a disk 121. Interval of the track 15 is so formed that the interval becomes gradually wider from outside to inside such as A=1.6mum, A1=(1.6+x)mum, A2=(1.6+2x)mum...(here, x=0.1mum or more). Accordingly, when interval B between + or - primary diffracted lights 3, 4 becomes N times 1.6mum, the difference of intensity of the two diffracted lights does not become zero, and therefore, a tracking error signal can be detected. Thus, distinction can be made from the case where three diffracted lights are on the track simultaneously (in this case tracking error is zero).

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a signal adjusting r4 for adjusting tracking signals of an optical information processing device such as an optical pickup device that reads information from a digital audio disc, for example.
Regarding school.

[Technical background of the invention and its problems]

In an optical pickup device, a light beam emitted from a semiconductor laser is divided into three beams, a 90th-order beam and a ±1st-order beam, by a diffraction grating, and is focused onto a single point on a digital audio disk by an objective lens. The Oth-order diffracted light is used for signal readout and focus adjustment, and the ±1st-order diffracted light is used for tracking adjustment. The three light beams reflected by the recording surface of the digital audio disk are finally guided by an optical system to a photodetector that detects the reflected light of the light beams and converts it into an electrical signal.

There is a first recording surface on the digital audio disc.
As shown in the figure, pits 1 in which optical information is recorded in a chain are provided. The signals recorded in this way are read out by the 0th order new signal 2 narrowed down to a minute spot. To do this, it is necessary to constantly correct the new bit 2 so that it always passes through the center of bit 1 recorded in a chain.

As a method to realize this tracking, 0th New Party 2
The ±1st-order diffracted light 3.4 is irradiated at appropriate intervals before and after the , and are arranged at a slight angle of inclination α from the center line of the track. The new parties 3 and 4 shall cut the same amount of tracks both times. If the servo mechanism performs multiple position corrections so that the difference in intensity between the two times reflected from the disk is always zero, the zeroth time second time 2 will always trace the center of the track. However, when using a digital audio disc, In this case, the track pitch A is constant at 1.6 μm.

With a disc like this, it is impossible to confirm that the three diffracted lights are on one track. That is, ±1st-order diffracted light 3, 4
As long as the difference in intensity is zero (the tracking error signal is zero), the distance between the two beams 3.4 is zero, as shown in Figure 1, and the three diffracted beams 2.3.4 fall on the same track. Not only when riding, but also as shown in Figure 2, when the distance B between the two new parts 3 and 4 is adjusted N times (1.6 μm x N) of 1.611 m, the three diffracted lights 2.3.4 Sometimes they rode on different trucks. In observation of tracking error signals, these cases were completely the same and could not be distinguished.

[Purpose of the invention]

The present invention has been made in view of the above considerations, and by varying the bit no-drag spacing, the difference in the intensity of the diffracted lights becomes zero only when three diffracted lights are on one track. The object of the present invention is to provide a signal conditioning disk that can be used as a signal conditioning disk.

[Summary of the invention]

The present invention detects that in a disk where information is recorded on spiral tracks, the intervals between the tracks where information is recorded are not constant, but are gradually wider or narrower, or are reversed. This is a distinctive signal conditioning disk.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 3 shows an example of an optical pickup device. That is,
For example, a substantially linearly polarized light wave emitted from a light source 5 such as a semiconductor laser enters a diffraction grating 6, is divided into three beams of 0th order and ±1st order, and is transmitted through a polarized beam 7' I) ivy 7, The collimating lens 8 converts the light into parallel light. The optical path of these three parallel beams is 10. The light is changed to a circular angle, passes through a quarter-wave plate io, becomes circularly polarized light, and enters the objective lens 11. The light emitted from the object lens 11 is converged onto the information recording surface of an optical information carrier, such as a digital audio disc 12, to form a minute spot of 3g. Each light beam reflected from the information recording surface of the disk 12 travels backward along the optical path,
By means of the quarter-wave plate 10 and the light control beam splitter 7, most of the light flux passes through the collimating lens 8 and the astigmatic optical system 13 formed by a cylindrical lens and a concave lens, and is transmitted to a light source such as a photodiode for photoelectric conversion. incident on the detector 14. The output signal of this photodetector 14 includes a focus control signal and a tracking control signal in addition to the information signal. The tracking control signal is applied via a signal processing circuit to a tracking coil provided in a movable part that holds all of the objective lens 1, and the movable part is all driven and controlled to perform tracking control.

Instead of the digital audio disc 12, the fourth
Tracking of the optical pickup device is adjusted using a tracking error signal adjustment disk 121 as shown in the figure. On the disk 12, information is recorded on spiral tracks 15. As shown in Fig. 4, the distance between the track numbers 5 is A
= 1.611m, A I = 1.6 + x
μm.

A2=1.6+2'xμm 'r''・(However, x
= 0.1 or more). Therefore, as shown in FIG.
6 μmXN), a tracking error signal can be detected because the difference in intensity between the two times is not zero. In this way, it is possible to distinguish from the case where the three diffracted beams 2.3.4 are simultaneously on the track (in this case, the tracking error signal is zero).

The track spacing of the signal adjustment disk is 1.6 μm from the outside to the inside.

1, 6-x thin, 1.6-2xμm...(However, x
= 0.1 or more), it may be formed so that it becomes narrower little by little, or it may be formed so that it becomes gradually narrower (=0.1 or more).
The narrowed portion may be formed so as to turn back.

〔Effect of the invention〕

As described above, according to the present invention, by varying the track spacing of pits in which information is recorded, zero-order, ±
It is possible to provide a signal adjustment disk that can distinguish between a case where three first-order diffracted lights are simultaneously on the same track and a case where the three first-order diffracted lights are simultaneously on different tracks.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining the relationship between the laser diffracted light and the information recording track; FIG. 3 is a configuration explanatory diagram showing an example of the optical system of the optical pickup device 4;
The figure is a schematic plan view showing one embodiment of the present invention, and FIG. 5 is an enlarged view of a part of FIG. 4. No...pit, 2...0th new party, 3.4...±
1st-order diffracted light, 12th...tracking error signal adjustment disk, 15th...track. Applicant's agent Patent attorney Takehiko Suzue Figure 1 Figure 2

Claims (1)

[Claims] 1. A signal adjustment disc on which information is recorded on spiral tracks, the disc having different intervals between tracks on which information is recorded.