JPS60229251A - Optical information carrier - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention Field of the Invention The present invention relates to an optical information carrier used in an optical recording/reproducing device that uses a laser or the like as a light source to focus a light beam into a minute spot to record or reproduce information. It is.

Conventional configuration and its problems In optical recording and reproducing devices, information is recorded or reproduced by rotating 11 disc-shaped information carriers and irradiating them with a laser beam as a minute spot light with a diameter of 1 μm or less. .

In such an apparatus, a guide track that guides a track to be recorded is formed with an uneven groove-like structure for reasons such as increasing the density of recording tracks, discrete partial writing, or erasing.

The guide track is identified based on the far-field pattern of the reflected laser beam reflected by the guide track, with the light intensity distribution being biased on both sides of the guide track direction. This bias is photoelectrically converted by a photodetector having two light-receiving sections arranged such that the dividing boundary is parallel to the tangential direction of the guide track, and is applied to the tracking control means. Therefore, when a minute spot light is focused on an information carrier and scanned across the guide track, each time the light spot passes through the guide track, a difference signal between the outputs of the two light receiving sections of the photodetector in the tracking control direction is generated as the signal traverses the track. Since a signal is obtained, the number of tracks traveled by the minute spot light on the information carrier can be determined by counting the number of crossing signals. therefore,
If the track search scanning is stopped when the count of the number of crossing trunks matches the target number of moving trucks, a high-speed track search can be performed.

In order to accurately perform the above-mentioned high-speed trunk search, it is necessary to accurately count the number of crossing trucks. However, optical discs do not only have guide groove trunks, but also address information on each track and information for further subdividing one track into smaller parts, which are cut into the optical disc in advance using the uneven grooves. There is also. In this way, when the minute spot light crosses the guide groove track, only the groove crossing signal does not necessarily appear in the photodetector output.

Since dust, scratches, etc. on the disk and address and sector information appear in the photodetector output, they are mixed into the groove crossing signal and become noise components.

The deterioration in the counting accuracy of the number of traversed tracks due to these noise components increases as the guide track traversal frequency of the spot light increases. Therefore, the speed of one search is limited in order to ensure the stability of the track search, resulting in a disadvantage that the search takes time.

OBJECTS OF THE INVENTION The present invention eliminates the drawbacks of the above-mentioned conventional examples and provides an optical information carrier that enables stable track searching even when the guiding trunk crossing frequency of spot light is high, thereby improving the track searching of an optical recording/reproducing device. The purpose is to shorten the time.

Structure of the Invention The present invention forms a groove-shaped guide track for guiding a light beam on a substrate, and arranges a region having substantially no guide track between the spiral guide tracks. It is an optical information carrier that enables stable high-speed track searches even when traversing spots at high speed.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a plan view of an optical information carrier according to an embodiment of the present invention. In this embodiment, the information carrier has a disk shape.

FIG. 2 is a partial cross-sectional view of a portion of the disc-shaped information carrier 1 indicated by diagonal lines in FIG.

On the disc-shaped information carrier 1, there is a depth δ indicated by 3 in FIG.
, a guide track with a groove width W is formed in a concentric or spiral shape. The track pitch of these guide tracks is P.

Furthermore, the regions 2-a to 2-t in FIG. 1, which do not substantially have a guide trunk, are provided one at each nth position of the guide track 3.

In this embodiment, the regions 2-8 and 2-f in FIG. 2 that do not substantially have a guide track are formed by forming flat portions having a width A.

Next, the track search operation of the optical recording/reproducing apparatus using the disc-shaped information carrier of this embodiment will be explained.

Detection of the number of light spots crossing the guide track 3 is as follows:
This is carried out by a known method, for example, as disclosed in Japanese Patent Application Laid-Open No. 58-185043.

Detection of the number of times the light spot crosses the area having substantially no guide track, that is, the flat portions 2-a to 2-i of this embodiment will be explained with reference to FIGS. 3 and 4. .

FIG. 3 is a block diagram of a push-pull photodetector and intensifier, which is the most widely used tracking error detection method for optical recording and reproducing devices.

Reference numeral 4a indicates a photodetector in the inner circumferential direction of the disc-shaped information carrier 1, and 4b indicates a photodetector in the outer circumferential direction.

Further, 7 represents a light spot where the reflected light from the disk-shaped information carrier 1 is projected onto the photodetector.

6Vi indicates a pre-sum amplifier; 8 indicates its output terminal; 6 indicates a pre-differential amplifier; 9 indicates its output terminal.

FIG. 4 shows the photodetector output waveform, the sum signal, and 7 shows a temporal change waveform of the amplitude of the difference signal output.

1 Q a indicates the output waveform of the photodetector 4a, and 10b indicates the output waveform of the photodetector 4b.

11 represents the difference signal waveform of both outputs, and 12ij represents the sum signal output waveform.

In the flat portions 2-a to 2-i, since no diffraction phenomenon occurs at the edges of the groove-like dormitory tracks, the inner circumferential side photodetector 4
a, Output waveforms 10a and 10b of the outer circumferential side photodetector 4b both have an output of 7 rasots and are equal.

Further, this is the same when the light spot crosses from the outer diameter to the inner diameter of the disc-shaped information carrier 1, and conversely when it crosses from the inner diameter to the outer diameter.

Therefore, the difference 'j)11i;jo level becomes the sum signal 1
2 is a flat waveform with a constant level.

From the above, by detecting that the sum signal 12 is equal to or higher than the constant level L shown in FIG. 4 and the difference signal 11 is at the O level, the area 2- It is possible to detect that the light spot has crossed a-2-i.

The above guide track crossing number detection means and guide trunk n
By using a means for detecting the number of crossings in an area that does not substantially have a guide trunk, which is provided for each book, it is possible to shorten the time required to search for a track.

This is because even when a light spot crosses a guide track at high speed, the isometric track crossing frequency that crosses an area with substantially no guide track is 1 of the guiding track crossing frequency.
/n, so the moving distance of the light spot can be counted with high accuracy.

Next, a second embodiment of the present invention will be described using FIG. 6.

FIG. 6 is a partial cross-sectional view of the disc-shaped information carrier 1. FIG. In this embodiment, the regions 2-e and 2-f that do not substantially have a guide track are shaped by setting the optical groove depth to λ/4 and the width to B, so that the optical Detectors 4a, 4b
The differential output waveform of is at 0 level as in the first embodiment.

Also, the sum signal output is larger than that when the signal crosses 12 guide tracks 3.

Therefore, as in the first embodiment, by detecting the 00 level of the difference signal and the level of the sum signal, an area having substantially no guide track, in this embodiment, an area with a groove depth of λ/4 is detected. You can count the number of times the light spot crosses. Therefore, the same effect as the first embodiment can be achieved. Furthermore, in this embodiment, the method of forming a region having substantially no guide track, that is, the method of setting the groove depth to λ/4, allows the groove width to be smaller than the method of forming a flat portion. . Therefore, there is an advantage that the efficiency of using the information carrier can be improved.

In the first and second embodiments, the guide track has a circumferential shape or a spiral shape, but it may also have a striped shape.

Effects of the Invention In accordance with the present invention, groove-shaped guide tracks for guiding the light beam are formed on the base plate 2, and flI regions having substantially no guide tracks are arranged between the spiral guide tracks. This makes it possible to provide an information carrier that allows stable trunk searches even when the optical scooter traverses the guide track at high speed, and this has great practical value.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the information carrier of the present invention, FIG. 2 is a partial sectional view of an embodiment of the information carrier of the present invention, and FIG. 3 is an optical recording/reproducing method using the information carrier of the present invention. Configuration circuit diagram of trunking detection system using push-pull method of device, No. 4
The figure shows the output waveform of the photodetector and the sum and difference output waveforms.
The figure is a partial sectional view of a second embodiment of the information carrier of the invention. 1... Information carrier, 2-a to 2-i...
・A region that does not substantially have a guide track, 3...
・Guidance track. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 1? -ノ and -j Figure 3, ri

Claims (1)

Scope of Claims (11) Groove-shaped guide tracks for guiding the light beam are formed on the base, and between the groove-shaped guide tracks,
1. An optical information carrier characterized in that an area having substantially no guide track is arranged. An optical information carrier according to claim 1, characterized in that the optical information carrier is formed.