JPS6356610B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to an optical information recording and reproducing method for optically recording and reproducing information using a laser beam.

Technical background of the invention and its problems Recently, so-called optical disk devices have been attracting attention as recording and reproducing devices that record high-density, large-capacity information. This means, for example, that the laser beam has a diameter
The beam is narrowed down to about 1 μm and irradiated onto a disk-shaped recording medium called an optical disk, with a width of 0.6 to 1 μm.
Recording is performed by forming pits with a length of 1 to 2 μm,
This is reproduced using a similar laser beam with reduced power.

This type of device generally records information in recording units (hereinafter referred to as sectors) each consisting of a fixed number of bits, but an important problem is how to detect the starting position of each sector during playback. becomes. For this reason, in the past, the number of rotations of the optical disk during recording and playback was kept constant, and recording area 1 was moved to the first sector in synchronization with the number of rotations of the optical disk, as shown in Figure 1.
Recording is performed in n divisions from S ₁ to the n-th sector S _o , and during playback, starting from the rotation start mark 2 that has been placed on the optical disc in advance by some method,
A method has been used in which the starting position of each sector S ₁ -S _o is detected by calculation.

However, this method has the disadvantage that the number of rotations of the optical disk needs to be constant, so as shown in Figure 1, the sector length becomes longer towards the outer periphery of the disk, resulting in a decrease in recording capacity. had.

In order to increase the recording capacity, the optical disc may be rotated at a constant linear velocity, but in this case, the starting position of a sector cannot be detected using conventional methods.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an optical information recording and reproducing system that can easily detect the starting position of each sector even when the linear velocity of the rotation of an optical disk as a recording medium is constant.

SUMMARY OF THE INVENTION The present invention provides a non-recording area before each sector of a recording track on a recording medium, thereby detecting the starting position of each sector during reproduction.

Embodiments of the Invention FIG. 2 is a schematic configuration diagram of an optical disk device to which the present invention is applied. The optical disk 11 is driven at a constant linear velocity by a motor 12 connected to a motor drive circuit 13.
That is, when the distance from the center of the disk 11 to the recording/playback position is r, and the rotation speed of the disk 1 is w,
It is rotated so that 2πrw=constant. 14
is a well-known recording/reproducing optical system including a laser oscillator, lenses, mirrors, etc., and irradiates the disk 11 with a laser beam to optically record and reproduce information.

Information is recorded on the optical disk 11 using an input device 15.
The information data transferred from the write data buffer 17 through the interface 16 and stored in the write data buffer 17 in sector units consisting of a fixed number of bits, and a blank signal having a length corresponding to the fixed number of bits generated by the blank generation circuit 18, blank signal,
This is done by applying the information data to the write control circuit 19 in order.

On the other hand, when reproducing information from the optical disc 11, an electric signal corresponding to the reflected (or transmitted) laser light from the optical disc 11 modulated by the presence/absence of pits is extracted through the read control circuit 20, and this signal First, the blank detection circuit 21 detects the blank signal to detect the sector start position. After this detection, the read control circuit 20 demodulates the information data in a manner similar to the conventional method, and transfers the information data sector by sector to the output device 23 via the read data buffer 22 and interface 16.

FIG. 3 shows a recording pattern on the optical disk 11 when the entire surface is recorded by the recording method according to the present invention, and each track 32 of the recording area 31 is a non-recording area formed by the blank signal. It is divided into sectors 34 consisting of a fixed number of bits across 33, and the length of the outermost sector is
L ₁ and the innermost sector length L _o are equal.

The non-recording area 33 is, for example, a non-pit portion 41 as shown in FIG. 4, and its length L _B is the length of the pit 42 according to the information in the sector 34.
It has been chosen sufficiently longer than lp. As an example, if the maximum value of l is 2 μm, L _B is about 100 to 200 μm,
In other words, in terms of the number of pits, about 50 to 100 pits is sufficient.

Effects of the Invention As described above, according to the present invention, by adding a non-recording area immediately before a sector, the starting position of each sector can be easily detected without depending on changes in the rotational speed of the disk. Therefore, by keeping the linear velocity of the disk constant, even if you try to increase the recording capacity by equalizing the recording density on the outer and inner circumferences, correct playback can be performed and random sector access can be achieved. It becomes easier.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and the same effect can be obtained even when the number of bits of information data constituting one sector is changed between, for example, the outer circumference and the inner circumference. . Further, the non-recording area for detecting the start position of a sector may be provided in the form of a continuous pit. Furthermore, the present invention can also be applied to an optical disk device of a constant rotation speed type.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a recording method in a conventional optical disk device, FIG. 2 is a schematic configuration diagram of an optical disk device to which an optical information recording/reproducing method according to an embodiment of the present invention is applied, and FIG. This figure is a diagram schematically showing a recording pattern on an optical disk in the same embodiment, and FIG. 4 is a diagram showing a specific example of a method for forming a non-recording area for detecting the start position of a sector. 11... Optical disk, 12... Motor, 17...
... Blank generation circuit, 21 ... Blank detection circuit, 31 ... Recording area, 32 ... Recording track, 33 ... Non-recording area, 34 ... Sector (recording unit), 41 ... Non-pit portion, 42 ... Information pit.

Claims (1)

[Claims] 1. In a method of optically recording and reproducing information sector by sector by irradiating a recording medium with a laser beam, a non-recording area is provided in front of each sector of a recording track on the recording medium, An optical information recording/reproducing method characterized in that during reproduction, the start position of each sector is detected using this non-recording area. 2. The recording medium records information as a row of pits, and the non-recording area is a non-pit portion or pit formed sufficiently longer than the pit corresponding to the information in the sector. The optical information recording and reproducing method according to item 1. 3. The optical information recording and reproducing method according to claim 1, wherein the recording medium is disk-shaped and rotated at a constant linear velocity during recording and reproducing information.