JPH01173450A - Information recorder - Google Patents

Abstract

PURPOSE:To prevent track runout, and simultaneously, to reduce an error at the time of write and read by providing a supplementary light beam, and supplementing a part where is not irradiated by a guide groove forming beam by the supplementary light beam. CONSTITUTION:Time from the point of time that the unirradiated part is detected by the detection signal of a detector 22 until a position to be irradiated by the supplementary light beam C reaches the unirradiated part is calculated, and from this point of time that it comes to said time, an acoustic optical modulator 32 is driven, and the supplementary light beam C is switched on. Besides, simultaneously, at the same time that the length of the unirradiated part 45 is detected from the detection signal of the detector 22, the length of time corresponding to said length is calculated, and the supplementary light beam C is kept on for the calculated length of time. Thus, the unirradiated part of the light beam A is supplemented by the supplementary light beam C, and the occurrence of the unirradiated part is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to an information recording device using an optical disk having guide grooves between recording tracks, and is applicable to video disk devices and other optical disk devices.

(Prior art) Information recording devices that use optical discs as information recording media use a groove-to-groove recording method in which guide grooves are formed between the recording tracks of the optical disc, and tracking is performed along the guide grooves to record high-density information. There are some attempts to collect debt.

FIG. 6 shows the relationship between the reading and writing beams and the disk according to the above-mentioned groove-to-groove recording method.By rotating the disk, the beam 43 on the disk moves between consecutive guide grooves 41 at a constant rate as shown by the arrow 44. Runs relative to the direction of. The pitch of the guide grooves 41 is, for example, 1.6 μm, and between the grooves 41, information pits 42 such as addresses and subsequent data writing areas 42a are provided.

The guide grooves 41 and the information pits 42 are usually formed using the following equipment and through the following steps. In FIG. 3, a light beam A for forming a guide groove and a light beam B for forming an information recording focus are focused by an objective lens 12 on the photoresist layer of a substrate 10 made of a large-diameter flat glass or the like having a photoresist layer on its surface.・It is illuminated. light beam A
, B are used as laser beams. The irradiation position a of the light beam A and the irradiation position of the light beam B on the resist layer of the substrate IO are shifted in the radial direction of the substrate 10 by a distance of about 1/2 of the pitch of the guide grooves 41. The substrate 10 is driven to rotate, so that the light beams A and B move relative to the substrate 10 in the direction indicated by the arrow. At this time, the light beam A
By being continuously illuminated, the portion where the guide groove is to be formed is continuously illuminated, and the light beam B is turned on and off depending on the information bit 42 to be formed. In addition, due to vibration of the substrate 10, etc., the illumination positions a and b of the light beams A and B may be affected.
Focus servo is applied to the lens 12 by a known method to prevent the lens from shifting. The photoresist layer on the substrate 10 is thus illuminated by the light beam A in a concentric or spiral manner. By developing this, a master as shown in FIG. 4 is obtained. The portion illuminated by the light beam A becomes a guide groove 41, and the portion illuminated by the light beam B becomes an information pit 42.

Next, after applying a conductive film to the substrate 10 as a master, the guide grooves 41 and the information bits 42 are transferred to a metal mold by electroforming. This metal mold is further replicated by electroforming, or the metal mold is used as a stamper as it is, and an optical disk substrate having guide grooves is replicated by injection molding, ultraviolet curing resin method, or the like.

The laser used to form the guide tj41 on the substrate 10 is an argon gas laser, a helium cadmium gas laser, or the like. On the other hand, the photoresist is a positive type resist such as the AZ series manufactured by Shisopray, the KMPR series manufactured by Kodak, and the 0FPR series manufactured by Tokyo Ohka, which have been commonly used in the semiconductor industry. Although these resists have good photosensitivity in the ultraviolet region, their sensitivity rapidly decreases on the long wavelength side.

Furthermore, in order to form guide grooves with a pitch of about 1.6 μm over a large area, the desired resolution cannot be obtained with ultraviolet mask exposure and focused light such as a laser beam is required, but lasers in the ultraviolet region are not yet available. Not developed. For this reason, the aforementioned gas laser, which can provide a large output even in the wavelength range to which the resist has low sensitivity, is used to manufacture optical disc masters.

However, gas lasers suffer from a momentary interruption phenomenon in which light emission is interrupted momentarily. If a momentary interruption of the laser beam occurs during the formation of the guide groove by the laser beam, a portion where the guide groove is not formed will occur. If an optical disc is duplicated using a substrate with a non-guide groove formed area, as shown in FIG. 7, a non-guide groove formed area 45 will also appear on the optical disc, which will cause errors in reading and writing. Tracking will be lost and access will become inaccessible. Although errors in reading and writing information signals are tolerable to some extent, inaccessibility is a fatal defect. When a momentary interruption occurs in the light beam B for forming information recording pits, it only results in a recording error and does not result in a fatal defect such as trunk detachment. Therefore,
When a single laser light source is branched to obtain the light beam A for forming a guide groove and the light beam B for forming an information recording focus, an unilluminated area may occur in both the guide groove and the information recording focus due to a momentary interruption of the laser beam. However, the formation of unilluminated portions in the guide groove portions, resulting in the formation of portions where no guide grooves are formed, is a fatal defect.

The allowable length of the non-guide groove portion depends on the tracking characteristics of the reading device, but in the groove-to-groove recording method, the allowable length is several tens to several tens.
It is 0 μm. If this permissible length is exceeded, tracking becomes impossible, and if an optical disc manufactured from a master disc having a non-guide groove portion exceeding the permissible length is used, the arrow 4 in FIG.
As shown at 4a, the reading beam comes off the recording trunk, making it impossible to read correctly. On the other hand, once the gas laser is instantaneously interrupted, the instantaneous interruption time ranges from several tens to several hundreds of m5ec. For this reason, gas lasers that are less prone to instantaneous interruptions are selected and used for master disc manufacturing. Then, the master disk where the momentary interruption occurred is discarded as defective.
Alternatively, even if a momentary interruption occurs, the rotation speed of the master disc is slowed down so that the area where the guide groove is not formed is a few μm within the allowable value, and the plate is manufactured in long exposure mode. It is necessary to take measures such as tracking the formation location or compensating for address reading. However, either method is disadvantageous in terms of product yield, workability, and cost.

(Purpose) The present invention has been made in order to solve the above-mentioned conventional problems, and an object of the present invention is to provide an information recording device that has good yield and workability in the master manufacturing process and can reduce costs. purpose.

(Structure) In addition to the light beam for forming guide grooves and information recording pits, the present invention provides a distance in the radial direction of the substrate from the convergence position of the light beam for forming guide grooves by one or an integral multiple of the guide groove pitch. Using an auxiliary light beam that can be focused on the position where
The auxiliary light beam is characterized in that when an unilluminated portion is detected due to a momentary interruption of the guide groove forming light beam, the substrate is illuminated after a predetermined time to compensate for the unilluminated portion.

Embodiments of the illustrated information recording apparatus according to the present invention will be described below.

In FIG. 1, reference numeral 10 is a substrate whose surface is coated with photoresist, 12 is an objective lens, A is a light beam for forming a guide groove, B is a light beam for forming an information recording focus, and a is a substrate 10 of the light beam A. b is the illumination position of the light beam B onto the substrate 10, and each of the above components is the same as the configuration of the conventional example shown in FIG. The two light beams A and B may be obtained from different laser light sources, or
A single laser light source may be split into two beams using a beam splitter, a birefringent crystal prism, or by means such as diffraction.

The following components are added to the above components. First, in addition to the above two light beams A and B, an auxiliary light beam C is used. This auxiliary light beam C is the light beam A, B
The light beam may be obtained from a laser light source separate from the light beam A or B, or may be obtained by branching from the light beam A or B by known means.

The auxiliary light beam C is focused through an objective lens 12 and illuminates the photoresist layer of the substrate 10. The illumination position C of the auxiliary light beam C on the substrate 10 is set at a distance in the radial direction of the substrate 10 from the converging position a of the guide groove forming light beam A on the substrate 10 by one or an integral multiple of the guide groove pitch. It is set to the same position as before. Therefore, the illumination position C on the substrate 10 by the auxiliary light beam C follows the illumination position a by the light beam A. An acousto-optic modulator 24 is disposed on the path of the auxiliary light beam C, and the auxiliary light beam C is turned on and off by a control signal input to the acousto-optic modulator 24. Note that the acousto-optic modulator 24
Instead, other on/off means may be provided, or the laser light source of the auxiliary light beam C itself may be controlled on/off. A polarizing plate 14 is placed on the path of the light beam A for forming the guide groove.
, a beam splitter 16 and a quarter wavelength plate 18 are arranged in this order, so that the beam splitter 16 reflects the diffracted light of the light beam A by the substrate 10 laterally. The light beam reflected by the beam splitter 16 is focused by a lens 20 onto a detector 22.
2 to detect the light beam A.

Now, while illuminating the substrate 10 with light beams A and B,
When 0 is rotationally driven, the light beam A sequentially forms guide grooves, and the light beam B forms information recording bits. Here, it is assumed that an unilluminated portion is created in a portion where a guide groove is to be formed due to a momentary interruption of the light beam A. Since the instantaneous interruption of the light beam A can be immediately detected from the output of the detector 22, the time from when the unilluminated area is detected by the detection signal of the detector 22 until the position illuminated by the auxiliary light beam C reaches the unilluminated area is The time is calculated, and the acousto-optic modulator 32 is driven to turn on the auxiliary light beam C from the time when this time is reached. Since the illumination positions a and c of the light beam A and the auxiliary light beam C are shifted in the radial direction of the substrate by the guide groove pitch or an integral multiple thereof, the above time calculation is easy. At the same time, the length of the unilluminated portion 45 is detected from the detection signal of the detector 22, the length of time corresponding to this length is calculated, and the auxiliary light beam C is turned on for the calculated time length. . By doing so, the unilluminated portion of the light beam A is supplemented by the illumination of the auxiliary light beam C, and as a result, the occurrence of unilluminated portions is prevented.

FIG. 2 shows an example of a control system for the acousto-optic modulator 24 based on the detection signal of the detector 22. In FIG. 2, the detection signal by the detector 22 is detected by the waveform shaping circuit 26.
The signal is then converted into a digital signal by an analog-to-digital converter 28. If there is an unilluminated portion due to momentary interruption of the guide groove forming light beam, the detector 22 detects this.
is detected, and from this detection signal, the calculation unit 30 calculates the time point and illumination time length at which illumination should be started by the auxiliary light beam,
Based on this calculation result, the acousto-optic modulator 24 is controlled through the drive circuit 32. Here, in the case of the CAV method, the illumination intensity and the illumination time length are calculated from the detected radial position of the unilluminated portion or the formatter address position, and the illumination of the auxiliary light beam C is started after a certain period of time. Further, in the case of the CLV method, the illumination start time and the illumination time length are calculated from the radial position or format address position, and the illumination of the auxiliary light beam C is started based on the results.

If a control system as shown in FIG. 2 is used, when the position where the auxiliary light beam should reach reaches the unilluminated area, the auxiliary light beam is turned on by the acousto-optic modulator 32, and the unilluminated area is covered with the auxiliary light beam. Illuminated and supplemented. By developing the substrate illuminated by the three light beams, a master disk with completely continuous guide grooves can be obtained, and by using this master disk, an optical disk substrate with completely continuous guide grooves can be obtained. .

(Effects of the Invention) According to the present invention, even if the light beam for forming a guide groove is momentarily interrupted, an auxiliary light beam is provided so that the portion not illuminated by the light beam for forming a guide groove is illuminated by the auxiliary light beam. Since the guide groove is compensated for by this, the guide groove is not interrupted, it is possible to prevent off-track, and it is also possible to reduce errors during writing and reading. Furthermore, it is possible to improve the yield and workability in the optical disc manufacturing process, thereby reducing the manufacturing cost of the optical disc.

[Brief explanation of the drawing]

FIG. 1 is an optical layout diagram showing an embodiment of an information recording device according to the present invention, FIG. 2 is a block diagram showing an example of a control system applicable to the above embodiment, and FIG. 3 is a diagram of a conventional information recording device. FIG. 4 is a perspective view showing the guide grooves and information recording pits formed on the master disc; FIG. 5 is a perspective view showing another state of the guide grooves and the information recording pits; 6
The figure is a plan view showing the relationship between the optical disc and the light beam.
The figure is a plain view showing the relationship between an optical disc with an interrupted guide groove and a light beam. 10...Substrate, 41...Guide groove, 42...Information recording focus, A...Light beam for forming guide groove, B...Light beam for forming information recording pit, C...Auxiliary light beam. Red map 7

Claims (1)

[Scope of Claims] In an information recording device that uses a light beam for forming guide grooves and information recording pits on a substrate, in addition to the above-mentioned light beam, a distance of 1 part of the guide groove pitch from the convergence position of the guide groove forming light beam is provided. An auxiliary light beam that can be focused at a position separated in the radial direction of the substrate by a multiple or an integral number of times is used. An information recording device characterized in that the substrate is illuminated with light after a predetermined time to compensate for the unilluminated portions.