JPS5821336B2 - Optical discs and information recording devices - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical disc for recording digital information and the like in a form that can be optically recorded and reproduced, and a recording method therefor, and particularly to an optical disc suitable for additionally recording information and a recording apparatus therefor.

Recently, in optical discs, in order to record additional information, grooves are provided in advance to guide the light beam spot.
An additional recording method is proposed in which information is recorded by relying on this guide groove to align the light beam spot during recording.Pres
s information, Ph1lipsNov,
7th 1978.

However, in this conventional recording method, the depth of the groove in the information recording portion and the groove for guiding the light beam are made to be different from each other. This creates the inconvenience of having to form a .

Moreover, in the conventional additional recording method, the diffraction direction of the beam generated by the groove is used to guide the light beam, so two photodetectors are required, making the device configuration complicated. This has the disadvantage of becoming.

In view of this, the present invention aims to provide an optical disc and a recording device thereof suitable for performing additional recording.

<7' In order to achieve the above object, the present invention records pits at arbitrary intervals of one or more of the information pits to be additionally recorded, and causes the pit examples to slightly meander at a constant cycle. It is characterized by being recorded and used as a guide groove.

The present invention will be explained below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment of an optical disc according to the present invention.

In FIG. 1, pits in the guide groove are shown by solid lines (indicated by bunching), and pits □ to be additionally recorded are shown by dotted lines.

The pit spacing of the guide groove is additionally recorded pit 1 for simplicity.
It's in individual pieces.

The pit row of the guide groove is recorded so as to meander with a minute amplitude δ at a period T with respect to the additional groove direction, and the pit intervals are formed so as to have a period t.

The characteristics of such an optical disc are as follows.

That is, when first performing additional recording, the pre-recorded pit row meanderes by a minute amplitude δ, so that the light beam is Since it is possible to perform a tracking operation in which the spot accurately tracks the pit row, it becomes possible to additionally record information pits accurately and easily.

Second, since the pit string is always reproduced at a constant period T, this type of recording/reproducing device, such as a magnetic disk or magnetic tape, can accurately record and reproduce information even when the speed of the record carrier varies. PLL (phased,
Locks, loops) are easy to pull in and difficult to remove.

Thirdly, since the position of the additionally recorded pit can be determined based on the position of the pit in the guide groove, there is little timing error when reproducing information.

Fourthly, when additional recording is performed, it is usually a so-called gradation type recording in which holes are made in a metal thin film that is a recording medium.

As a guide groove, the present invention can be applied to both a phase-type recording format in which pits are formed in the depth direction of a recording medium and the aforementioned gradation-type recording format.

In particular, in the case of the light and shade type, there is no need to process the unevenness on the record carrier in advance, and a flat carrier can be used, and bisecting information such as addresses can be added at will, making it possible to respond flexibly to the demands of disc users. .

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 2a shows a cross section of the recorded pit row.

Numerals 1-1 to 1-5 are pits for guiding, and the depth of the pits is formed to be 1/4 of the wavelength λ of the laser beam used for reproduction.

As the record carrier 2, PVC (polyvinyl chloride), which is commonly used as a replica disk, or a photoresist coated on a glass disk is suitable.

FIG. 2 is a sectional view of a disc for additional recording.

That is, the metal thin film 3 is formed by vapor deposition or the like on the pit row shown in FIG. 2a.

FIG. 2C shows the surface portion of FIG. 2, and shows the relationship between the guide pits and additional recording pits in the same way as FIG. 1.

Note that this embodiment shows a case where the recording pit and the guide pit are approximately equal in size.

A third embodiment of the invention is shown in FIG.

The cross-sectional form of the guide pit is the same as that shown in Fig. 2a, and the preparation of the additional recording disk is also the same as shown in Fig. 2. In order to make it easier to separate the pits, the sizes of the guide pits 5-1 to 5-5 are changed to the recording pits 6-1 to 6-1.
It is formed thicker than the thickness of 0.

By doing so, it becomes easy to separate the guide pits and the recording pits by utilizing the difference in signal level from the waveform during reproduction.

Further, a fourth embodiment is shown in FIG.

The cross-sectional form of the guide pit is shown in FIG. 4a.

In the figure, the depth of the pit is d.

The additional recording disk is prepared in the same manner as shown in FIG. 2, but the sizes of the guide pits 7-1 to 7-5 are made smaller than the recording pits for the same reason as in the second embodiment.

In this way, guide pits and recording pits can be separated from the reproduced signal waveform.

The depth d may be 1/4 of the reproduction laser wavelength λ, but is preferably 1/8.

Further, a fifth embodiment is shown in FIG.

The guide pits are recorded in the form of shading holes made in a thin metal film formed on the disk surface.

Even in this case, it is desirable to record the guide pits with relatively different sizes in order to distinguish them from the recording pits, as in the third and fourth embodiments.

Guide pits 10-1 to 10-5 are recorded on the metal thin film 3 formed on the substrate 12.

By recording the guide pits in a light and shade type, an additional recording disk that can be flexibly handled as described above can be created.

By creating the guide grooves described above, additional recording can be performed reliably.

In the above embodiments, the guide pit interval is shown to be every other recording pit or every two recording pits, but it is sufficient that a predetermined number of recording pits exist between the guide pits, and the present invention is applicable to such intervals. Of course, it is not limited to.

A recording apparatus according to the present invention for creating the guide pits described above will be explained using FIG. 6.

A laser beam 72 emitted from an Ar+ laser 61 for recording passes through an optical modulator 62 and undergoes intensity modulation, is adjusted to the optimum power for recording through a light attenuator 73, and is adjusted by a reflecting mirror 63. It is reflected and deflected by a small amount in the direction of the rotation radius of the disk through the optical deflector 64, and a minute spot of about 1 μm is etched onto the surface of the disk 66 by the objective lens 65.

The disk 66 rotates about a rotating shaft 71 in the direction of the arrow.

This rotational movement is caused by a motor 68 via a spindle 67.

The force from the drive 69 with known means is transferred via the arm 70 to the disk 66 and the spindle 67 to the motor 68.
Together, the disk is driven in the direction of the arrow.

Repetition frequency f with period t.

The output from the oscillator 76 (with a repetition frequency that is an integer fraction of the highest repetition frequency of the signal to be recorded) and the output from the oscillator 77 with a repetition frequency f1 having a period t is added to an adder? 51 are added together and input to an optical modulator 62 to modulate the light.

Since the disk rotates at a constant speed in response to the fo signal, guide pits with a period t as shown in FIG. 1 are formed.

Although not shown in FIG. 1, fl also forms pits that determine the phase of minute vibrations.

On the other hand, the output from the oscillator 78 having the period T1 and the repetition frequency f2 is input to the synchronization circuit 74, synchronization is performed by the output of the oscillator 77, and this output is input to the optical deflector 64.

By doing this, the light beam vibrates slightly on the disk surface, and meandering recording of a pit row with a period T shown in FIG. 1 is performed.

In order to create the guide pits described above, in this embodiment, a glass master disk as a record carrier is coated with photoresist and recorded with the recording device shown in FIG. You can use replicas made through this process.

In the fourth embodiment, a glass disc or an acrylic disc on which metal is deposited can be used.

The size of the guide pit can be controlled by changing the amount of transmitted light of the light amount attenuator 73, which changes the thickness of the deposited film in the rotational direction, by the rotational movement 1 in FIG.

That is, if the amount of transmission is large, the pits will be large, and if the amount of transmission is small, the pits will be small.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining one embodiment of the structure of a disk according to the present invention, and FIGS. 2, 3, 4, and 5 are diagrams for explaining the configuration of other embodiments of the present invention. , FIG. 6 is a diagram showing the configuration of an embodiment of the recording apparatus of the present invention.

Claims (1)

[Claims] 1. In an optical disc on which information pits are recorded in a form that allows information signals to be read optically, pit rows are recorded at predetermined constant intervals, and the pit intervals are recording portions of information signals. An optical disc characterized by: 2. In an optical disc on which information pits are recorded in a form that allows information signals to be optically read, pit rows are recorded at predetermined regular intervals, and the pit row meanders in the rotational direction of the optical disc at regular intervals, An optical disc characterized in that the pit interval is a recording portion of an information signal.