JPH01296432A - Optical information recording system - Google Patents

Abstract

PURPOSE:To obtain the high density of recording information in the range of conventional tracking technique by changing an information recording pattern in one track and changing the condition of an information bit. CONSTITUTION:Since the information recording pattern in one track is a system to form the plural bits of an (a)-column and a (b)-column in the width direction of the track, the signal of a multi-value level can be obtained at the time of reproducing and information can be recorded in respective bit strings (a) and (b) as well. Further, as the other system, a bit width is multi-valued so that bits 10 and 11 can be the bit of a width W1 and bits 12-15 can be the bit of a width W2. Then, the high density can be obtained for the recording information. By the way, in the above-mentioned system, when the bits are continued only in one side like bits 5-8 after an A-point, a same condition as the shifting of the track to left is obtained and the center of the track is not correctly tracked. Then, correct reading can not be executed. In the latter system, the same condition is generated and as a countermeasure to such a condition, the bit is not concentrated only to one track but a condition to be balanced in right and left sides is obtained.

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to the recording of information using light, and particularly relates to a method for increasing the density of recorded information and a technology for solving the accompanying tracking problems. It is something.

[Background of the Invention] In recent years, methods of high-density information recording on optical discs and the like have been actively researched. Generally, to record information at high density,
In order to increase the amount of information per unit area of a recording medium, it is necessary to form recording pits as small as possible. For this reason, it is ideal to use a light source with a short wavelength for recording light in order to reduce the problem of diffraction. However, short wavelength oscillation of semiconductor lasers, which are small and inexpensive light sources that can be applied to recording and reproducing positions, has been a difficult problem, so it has not been easy to improve recording density.

However, in recent years, short wavelength oscillation of semiconductor lasers has become possible (for example, in addition to the conventional infrared region, it has become possible to use them in the visible light region, and S Hl, which is a wavelength conversion element using nonlinear optical materials) Advances in device research have made it possible to form a smaller light spot than before.

However, in optical information recording media, the higher the recording density becomes by recording information using such small pits (not limited to concave or convex pits), the more accurately the tracks containing those pits are recorded or It is also necessary to improve the tracking technology in which the optical spot for reproduction follows.

Furthermore, on the other hand, for general-purpose information recording media such as optical discs, it is important to unify their properties, information recording and reproducing methods, and disk surface shapes such as groove structures. It has been desired to achieve high density of information within a shape.

[Objective of the Invention] The object of the present invention is to: - In view of the current situation where minute recording pits are being realized, it is possible to increase the density of information within the surface shape of a conventional recording medium and within the conventional tracking technology. 1] The goal is to provide a recording method that can be used.

[Summary of the Invention] In order to achieve the above-mentioned objective 1, first of all, as a first invention, a plurality of pit groups having a constant pit length in the force direction and a pit length of a track of an optical recording medium are provided. A recording method that forms pits on the left and right sides of the center of the track when the number of pit groups is even, and pits located at the center of the track when the number of pit groups is odd. To provide an optical information recording method, in which pits on the left and right sides of the track are formed so that the number of pits in the longitudinal direction of the track is balanced for tracking detection.

Another invention for achieving the object of item 1 is a recording method in which the pit length is constant in the longitudinal direction of the track of an optical recording medium and different pits are formed, and the change in the pit is Provided is an information recording method characterized in that the information is formed so as to change symmetrically with respect to the center of the information recording method.

In the present invention, a pit refers to a shape such as a concave shape or a convex shape, and is not limited to a recording method thereof, and generally refers to a medium position where information is recorded.

[Function] According to the above two inventions, there is an advantage that information can be recorded at high density by simply changing the information recording pattern within one track, and furthermore, information can be recorded at high density depending on the state of each information pit recorded within one track. , is formed so that there is no large change in the diffraction intensity of light in the longitudinal direction within the track, so there is an advantage that a conventionally known method can be used as the tracking means.

[Example] Hereinafter, a recording method according to the present invention will be described in detail based on an example.

First, before explaining the recording method of the present invention, a conventional recording method is shown in FIG. 5 in order to clarify the difference.

Conventionally, in an optical recording method used for an optical information recording medium such as an optical disk, the direction of force on one information recording track (hereinafter referred to as a track) is as shown in FIG.
11], and information was recorded by the arrangement of the pits. In FIG. 5, +00 is a track on the recording medium, and 101 to 104 are pits formed on the track.

The types of pits formed on this track can be roughly divided into three types: those that can only be reproduced, those that can form pits only once (write-once type), and those that can be rewritten.

A pit as shown in FIG. 5 is formed by a well-known information recording position, and information is read from the pit depending on an information reproduction position.

In contrast, the information recording method of the present invention is a method in which a plurality of pits are accommodated in the rj+ direction of the track, as shown in FIG. In FIG. 1, 1 is a track, and 2 to 8 are minute pits formed in the track 1. In FIG. In this way, by using a plurality of pits, it is possible to obtain multilevel signals when beef cattle are being fed. For example, 1/2 of track I+]
Using the following two pits 1-, no pit, pit 1-
By creating a 3-state pattern with 1 yi and 1-2 pips, re(1 Buddha has a level of 3 corresponding to this)
It is also FiJ Noh to take (i+'i) or to record 3 pieces of information for each pit row (pi, t), rather than increasing the amount of information like this. In other words, it can be considered that a plurality of tracks are formed within one track.

Another method of the invention is shown in FIG. In the same figure, 10
．． For II, rl is W, pit, for 12-15, rl is W2
This embodiment multivalues the information pit 1+ in the l track, and reads the state of the optical sensor 10 depending on the difference in rIJ to record the recorded information. This is a method of increasing density.

The type of pit l+ (level of multi-value) to be adopted can be changed depending on the ability of the optical sensor or the like.

However, in the embodiments shown in FIGS. 1 and 2 of the present invention, depending on the state of the recording data pit, the state with one pit always forms one pit only on either the left or right side of the track. This can cause tracking problems with conventional tracking methods. In other words, when a state with one pit continues for a long time, such as pits 5 to 8 after point A in FIG.
Even if a state in which there are two pits occurs in this state, correct reading will not be possible immediately because the center of the track will not be correctly tracked. Further, a similar problem occurs when the pitch l-11'l of the embodiment shown in FIG. 2 is made variable. That is, if the W2 rj+ pits are continuous on only one side of the track as shown in FIG. 2, the same problem as in the above example occurs (pits 12 to 15 after point A in FIG. 2).

As a countermeasure for this case, there are pit forming methods shown in FIGS. 3 and 4, respectively.

That is, in the embodiment shown in FIG. 1, the tracking problem is solved by forming the pits so that they are evenly balanced on the left and right sides, instead of concentrating on only one side of the track as described in 111J. It is something.

FIG. 3 is a diagram of an improved embodiment of the invention.

In FIG. 3, 1 is the track of the recording medium 1'', 20~
26 is a pit, 27 is a state with two pits, 28
~32 is a state with one pit and one E.

Even with one pit as shown in this figure, it is uniform.

By forming the number of pits on the right to be approximately the same, the third
It is possible to prevent the apparent track 1J from becoming narrower and shifting to one side as described in the figure. In this figure, ten pits are formed in a zigzag pattern for convenience of explanation, but if a balance can be achieved on average with the required dragging response time, the continuous pits may be biased to a certain extent. Formation is also acceptable. This is the same in the case of multi-value as described above and in the case of forming a plurality of tracks.

FIG. 4 is a diagram of an improved embodiment of the embodiment of FIG. 2. In the figure, 1 is the tenth track of the recording medium, and 7 is the tenth track of the recording medium.
1 is the pit of pit 11 W +, 72 to 76 is the pit of pit Ill W 2 (W + > W 2 ), 8
0 is a line indicating the center of the track.

In this example, the case where different pits [1] are used is targeted, and furthermore, the pits 71 to 76 are formed symmetrically with respect to the center line 80.

According to this configuration, the pits do not shift to one side of the track and no tracking problem occurs. In addition, +l of the pit
] Regarding the method of reproducing information, there is a method of distinguishing based on the size of the pit and the amount of light received by the optical sensor.

``Effects of the Invention'' 2. As explained in detail, the optical recording system of the present invention enables high-density recording, and also within the conventional recording medium's 1ai shape. Within the tracking technology, a recording scheme can be provided that allows information to be aggregated.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a recording pattern according to a first embodiment of the present invention. FIG. 2 is a diagram of a recording pattern of a second embodiment of the present invention. FIG. 3 is a diagram of the improved recording pattern in the first embodiment of the invention. FIG. 4 is a diagram of a recording pattern of an improved embodiment of the second embodiment of the present invention. FIG. 5 is a diagram showing a recording pattern of a conventional recording method. l: Information track on recording medium, 2-8.10-15.20-26.71-76 2 bits. Agent Patent Attorney Yohei Yama-to

Claims (2)

[Claims] (1) A recording method in which a plurality of pit groups with constant pit length and pit width are formed in the width direction of a track on an optical recording medium, and when there is an even number of pit groups, the center of the track The number of pits on the left and right sides of the track, and in the case of an odd number of pit groups, the pits on the left and right sides except for the pit located in the center of the track, are balanced in terms of the number of pits in the longitudinal direction of the track. An optical information recording method characterized by the formation of (2) A recording method that forms pits with a constant pit length and different pit widths in the longitudinal direction of the track of an optical recording medium, and the pit width changes symmetrically with respect to the center of the track. An optical information recording method characterized by the formation of