JPH05298697A - Optical disk and device for exposing optical master disk - Google Patents

Abstract

PURPOSE:To provide an optical disk and a device for exposing an optical master disk obtaining the wobble C/N of a pit and a groove sufficiently without increasing the jitters of a regenerative signal. CONSTITUTION:In the optical disk having a recording exclusive ROM area where the pit 1 of ROM data is formed and a recordable area where the tracking groove 2 is formed and the data is recorded by the exposure of a laser beam, the wobble amplitude Ap of the pit 1 is formed larger than the wobble amplitude Ag of the groove 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk used as a hybrid type CD-R medium or the like and an optical disk master exposure apparatus.

[0002]

2. Description of the Related Art Conventionally, a compact disc (CD) in which an audio signal is digitized and optically recorded, a CD-ROM in which data of various dictionaries are recorded, and further, a write-once type optical disc and a rewritable optical disc are used. Widely known. In addition, in recent years, a write-once type or rewritable optical disc of the CD format, and further, a ROM area,
An optical disc having a recordable area has been proposed.

In a hybrid type CD-R medium including such a ROM area and a recordable area, ROM data pits are formed in the ROM area.
Grooves for tracking are formed in the recordable area. Further, in this case, these pits and grooves are wobbled, and the absolute address on the disc can be detected by modulating the wobble amount with the absolute time data. The wobble amount is
For example, when the track pitch is 1.6 μm, about 30 nm
And the wobble frequency is set to 22.05 KHz. Conventionally, the pits and the grooves have the same wobble amount when the optical disk master is exposed.

[0004]

However, if the wobble amounts of the pit and the groove are made equal during the exposure of the optical disc master, the wobble C / N of the pit becomes lower than the wobble C / N of the groove. FIG. 3 shows the relationship between the wobble amplitude of the pit A and the groove B and the wobble C / N. In this case, the pit A according to the CD-R standard
The wobble C / N is standardized to be 25 dB or more, and the wobble C / N of the groove B is standardized to 35 dB or more. Therefore, if these standard values are not satisfied, the optical disc will have low reliability. Therefore, it can be seen from FIG. 3 that sufficient C / N can be obtained by increasing the wobble amplitude, and the jitter component of the reproduced signal does not deteriorate even if the wobble amplitude is increased in the pit portion, but the wobble amplitude is increased in the groove portion. By doing so, the jitter component of the reproduced signal increases.
Therefore, in the groove portion, in order to obtain a highly reliable reproduced signal, the wobble amplitude has to be made smaller than that in the pit portion within the range where the necessary wobble C / N is obtained. There is no control of the amplitude.

[0005]

According to a first aspect of the invention, a read-only RO in which pits of ROM data are formed
In an optical disc having an M region and a recordable region in which a groove for tracking is formed and data can be recorded by exposure to laser light, the wobble amplitude of the pit is formed larger than the wobble amplitude of the groove.

According to the second aspect of the present invention, the laser light emitted from the laser light source is condensed by the objective lens to be exposed on the optical disc master, so that the pits of the ROM data and the tracking data are recorded on the surface of the optical disc master. In the optical disc master exposure apparatus that forms a groove, the wobble amplitude and the exposure surface power are switched simultaneously with the switching of the exposure surface power of the laser beam when forming the pit and the groove. Control means were provided.

[0007]

According to the present invention, since the wobble amplitude of the pit is set larger than the wobble amplitude of the groove, a sufficient wobble C / N can be obtained without increasing the jitter component of the reproduced signal. Is possible.

According to the second aspect of the present invention, since the wobble amplitude exposure surface power switching control means simultaneously switches the wobble amplitude between the pit and the groove and the exposure surface power between the pit and the groove, the master disk is changed. It is possible to perform the exposure with high accuracy.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the invention described in claim 1 will be described with reference to FIG. FIG. 1A shows a pre-pit 1 as a pit of ROM data in a read-only ROM area.
Shows wobbles formed.
Further, FIG. 1B shows a state in which a pre-groove 2 as a tracking groove is wobbled and formed in a recordable area where data can be recorded by exposure to laser light.

Then, in the optical disc in which the pre-pits 1 in the ROM area and the pre-grooves 2 in the recordable area are thus formed, the wobble amplitude Ap of the pre-pits 1
Is formed larger than the wobble amplitude Ag of the pre-groove 2. In this case, pre-pit 1 is CD-
It is formed according to the data format of the ROM.
The depths of the pre-pit 1 and the pre-groove 2 are formed to be about 1200Å and about 450Å, respectively. The track pitches of the pre-pit 1 and the pre-groove 2 are both 1.6 μm, and the wobble frequency is 22.05 KHz.

As a specific example, the wobble amplitude Ag of the pre-groove 2 is set to 30 nm, whereas the wobble amplitude Ap of the pre-pit 1 is set to 36 nm, and the wobble C / N is 31 dB. The depths of the pre-pit 1 and the pre-groove 2 at this time are about 1200Å and about 450Å, respectively.

As described above, the wobble amplitude Ap of the pre-pit 1 is set to be larger than the wobble amplitude Ag of the pre-groove 2, so that the jitter component of the reproduced signal is not increased as described in the prior art. It is possible to obtain the wobble C / N, which makes it possible to provide a highly reliable optical disc.

Next, a second embodiment of the invention according to claim 1 will be described. Here, an example in which the wobble amplitude Ap of the pre-pit 1 is set to 48 nm is described in comparison with the specific example of the first embodiment described above. The wobble amplitude of the other pregrooves 1, the depths of the prepits 1 and the pregrooves 2, the track pitch, and the wobble frequency are all the same. Table 1 is a summary of these values, and as a result, the wobble C / N of the pre-pit 1 is from 31 dB to 34 d of the first embodiment.
You can see that it has changed to B. From such a thing,
Also in the case of the present embodiment, as in the first embodiment, a sufficient wobble C is achieved without increasing the jitter component of the reproduced signal.
/ N can be obtained.

[0014]

[Table 1]

However, the wobble amplitude of the pre-groove 2 is 30 nm and the wobble C / N of the pre-groove 2 is 37 dB. Next, an embodiment of the invention described in claim 2 will be described with reference to FIG. FIG. 2 shows the configuration of an optical disk master exposure device. The laser light emitted from the laser light source 3 is reflected by the mirror 4, and then passes through the analog A / O circuit 5 set to the exposure surface power where the prepits 1 and the pregrooves 2 have predetermined depths, Digital A
A wobble A set so that the prepit 1 and the pregroove 2 have a predetermined wobble amplitude via the / O circuit 6.
After passing through the / O circuit 7 and being reflected by the mirrors 8 and 9, the light is focused on the objective lens 10 and radiated onto the surface of the optical disc master 11, thereby pre-pits 1 of the ROM data and tracking pre-grooves. 2 can be formed. The optical disk master 11 is a turntable 12
It is placed on top.

In this case, the analog A / O circuit 5 is connected to an exposure power switching circuit 13 for setting the exposure surface power so that the prepits 1 and the pregrooves 2 have predetermined depths. Also, the wobble A / O
The circuit 7 is connected to a wobble amplitude switching circuit 14 which sets the prepits 1 and the pregrooves 2 to have a predetermined wobble amplitude.

In the optical disk master exposure apparatus having such a structure, in the present embodiment, the switching of the wobble amplitudes Ap and Ag of the prepits 1 and the pregrooves 2 is performed by the laser for forming the prepits 1 and the pregrooves 2. A wobble amplitude exposure surface power switching control means (not shown) is provided which is performed simultaneously with the switching of the light exposure surface power. Specifically, by inputting the switching signal 15 output when the wobble amplitude exposure surface power switching control means reaches a predetermined absolute address to the exposure power switching circuit 13 and the wobble amplitude switching circuit 14 at the same time, The exposure surface power and wobble amplitude are switched from pre-pit 1 to pre-groove 2 at the same time. By performing the switching at the same time in this manner, it is possible to perform the master exposure with high accuracy, and thus it is possible to provide an optical disc master exposure apparatus that can obtain a highly reliable optical disc.

[0018]

According to the present invention, there is provided a read-only ROM area in which pits of ROM data are formed, and a recordable area in which tracking grooves are formed and data can be recorded by exposure to laser light. Since the wobble amplitude of the pit is formed to be larger than the wobble amplitude of the groove in the optical disc, the sufficient wobble C / N can be obtained without increasing the jitter component of the reproduction signal. It is possible to provide a high-performance optical disc.

According to a second aspect of the present invention, the laser light emitted from the laser light source is condensed by the objective lens and is exposed on the optical disc master, so that the pits of the ROM data and the tracking data are recorded on the surface of the optical disc master. In the optical disc master exposure apparatus that forms a groove, the wobble amplitude and the exposure surface power are switched simultaneously with the switching of the exposure surface power of the laser beam when forming the pit and the groove. Since the control means is provided, by simultaneously switching the wobble amplitude of the pit and the groove and the pit and the groove of the exposure surface power in this way, it becomes possible to perform the master exposure with high accuracy, and thereby the reliability is improved. Providing an optical disc master exposure device that can obtain highly reliable optical discs It is those that can Rukoto.

[Brief description of drawings]

1A and 1B show a first embodiment of the invention according to claim 1, wherein FIG. 1A is a plan view of a pit portion, and FIG. 1B is a plan view of a groove portion.

FIG. 2 is a configuration diagram showing a state of an optical disk master exposure apparatus that is an embodiment of the invention described in claim 2;

FIG. 3 is a characteristic diagram showing a state of wobble C / N with respect to wobble amplitude.

[Explanation of symbols]

 1 Pit 2 Groove 3 Laser Light Source 10 Objective Lens 11 Optical Disc Master Ap, Ag Wobble Amplitude

Claims (2)

[Claims] 1. A wobble of the pit in an optical disk having a read-only ROM area in which pits of ROM data are formed and a recordable area in which a tracking groove is formed and data can be recorded by exposure to laser light. An optical disc having an amplitude larger than the wobble amplitude of the groove. 2. An optical disc for forming pits of ROM data and grooves for tracking on the surface of the optical disc master by condensing laser light emitted from a laser light source by an objective lens and exposing the laser light onto the optical disc master. In the master exposure apparatus, a wobble amplitude exposure surface power switching control means is provided for switching the wobble amplitude of the pits and the grooves at the same time as switching the exposure surface power of the laser light when forming the pits and the grooves. An optical disc master exposure apparatus characterized by the following.