JPS6224453A - Disc carrier for optical information recording and reproducing - Google Patents

Abstract

PURPOSE:To attain the address signal intensity of a certain level in any position in the diametral direction of a disc by providing information tracks where breadthwise dimensions of address pit parts are changed continuously in accordance with positions in the diametral direction of the disc. CONSTITUTION:Breadthwise dimensions (d) of rugged pits 3 in address pit parts 4 corresponding to address information are smaller than those D of guide grooves 5, and these breadthwise dimensions (d) are layer in the disc diametral direction of an arrow 100 according as going toward the outside periphery (i 0) in case of (a) and are smaller similarly according as going toward the outside periphery (i 0) in case of (b). Breadthwise dimensions of rugged pits are changed continuously along a curve I or II in accordance with lengthwise dimensions of rugged pits to control the variation of the address signal intensity due to the variation of length of rugged pits in positions in the disc diametral direction to a certain level.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a disc carrier for optical information recording and reproduction, which optically records and reproduces information using a laser beam.

2. Description of the Related Art In recent years, so-called optical disk devices have attracted attention as high-density, large-capacity recording and reproducing devices. For example, by focusing light such as a laser into a beam with a diameter of about 1 μm and irradiating it onto the recording member of an optical disk, pits with a width of 0.6 to 1 μm and a length of about 1 to 2 μm are formed on the recording member, and information is transmitted. is recorded and then reproduced using a similar laser beam. In addition, in order to access and record and reproduce high-density signals at high speed with a simple device, an optical information recording and reproducing disk carrier (on which an information track consisting of optically detectable address pits and guide grooves is formed) is provided. 2. Description of the Related Art Signals are recorded and reproduced along or within an information track of an optical disk (hereinafter referred to as an optical disk). A conventional example of such an optical disc is shown in FIG. 2 as a top view of the optical disc, and in FIG. 3 as a partially enlarged perspective view of an information track. In FIGS. 2 and 3, information is divided into fixed units and these divided units are called sectors), an address pit section 14 consisting of uneven pits 13 for recording and reproduction in sector units, and a guide for tracking. Information tracks 16 having grooves 15 are formed in advance over almost the entire surface of the substrate 12 in a spiral shape or in a concentric shape (concentric circles in FIG. 1) at a predetermined track pitch P. or,
As a method for detecting the address signal from the address pit portion 14 and the tracking signal from the guide groove 6 of the optical disc 1o described above, two A method is used in which a so-called two-split detector in which divided unit detectors are arranged side by side is arranged to obtain each of the above-mentioned signals. FIG. 4 shows the configuration of an optical system in an apparatus for optically recording and reproducing each signal from an optical disk by the method described above.

A laser beam 21 irradiated from a semiconductor laser 20 is collected by a focusing lens 22, and is sent to a beam splitter 23, λ/
The laser beam passes through the four polarizing plates 24 and is irradiated by the aperture lens 2s onto the information track 16 of the optical disc 10 which is being rotated by the disc motor 30. The reflected light from the information track 16 has its polarization plane changed by the λ/4 polarizing plate 25, is separated by the beam splitter 23, and is further received by the two-split detector 27 by the convex lens 26. With the above configuration, while performing stable tracking using the tracking signal detected from the guide groove, detecting and reproducing the address pit part and accessing all arbitrary sectors,
It becomes possible to record and reproduce information signals on the guide groove S as a pit string. Regarding the format of this type of information track, as already proposed by Philips of the Netherlands, etc., the information track 150 guide groove 6
is set to λ/8 (λ is the wavelength of the recording/reproducing light), which is a groove depth suitable for the far-field tracking method. On the other hand, the address pit portion 14 is set to a depth of λ/4 so that the reproduced address signal strength is maximized. It has been proposed that the width dimensions d, , D of the address pit portion 4 and the guide groove 6 are both constant (Fig. 3 &).

However, there is a problem in that it is extremely difficult to realize an optical disc having an information track in which the depth of the address focus portion or the guide groove is partially changed. Therefore, for example, the depth of the information track 16 is constant at λ/8, which is a depth suitable for the far-field tracking method, and the width dimensions d2 and 15 of the address pit portion 14 and the guide groove 15 are different. A format has been proposed that has a shape that satisfies the address signal from the address pit and the tracking signal from the guide groove (FIG. 3b).

Problems to be Solved by the Invention As optical discs become more dense, larger in capacity, and more reliable, it is necessary to shorten the length of the sector address pit to increase the amount of information that can be recorded in the guide groove. . When the address information from the address pit portion is the same or increased and the length dimension of the address pit portion is shortened, the length dimension of the uneven pit of the address pit portion becomes shorter. Further, when the optical disk is rotating at a constant rotational speed, in order to obtain the same address information, the length of the concave and convex pits in the address pit portion is different between the outer circumference and the inner circumference of the disk. In particular, when the uneven pits located on the inner circumference of the disk are smaller than the beam spot diameter for reproducing them, the intensity of the address signal from the address pit area changes due to changes in the amount of reflected light due to diffraction at the uneven pit area, as shown in Figure 5. The difference in address signal strength varies depending on the length of the uneven pits, resulting in a difference in address signal strength between the inner and outer peripheral positions of the disc, that is, the positions in the radial direction of the disc, resulting in a problem that the reproducing circuit system is complicated or the reliability of address access is significantly reduced.

The present invention has been made in view of the above points, and provides an optical information recording and reproducing disk drive having a simple structure and a high-quality information track in which the address signal strength is at a constant level at any position in the disk radial direction. The purpose is to provide the body.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention aims to improve the width of an address pit portion of an information track formed spirally or concentrically over the entire surface of an optical disk, especially the width of an address pit portion consisting of uneven pits corresponding to address information. The information track is provided with a width dimension that continuously varies according to the position in the radial direction of the disk.

Effect of the Invention With the above-described configuration, the present invention can provide an output in which the address signal intensity from the address pit portion is at a constant level at any position in the radial direction of the disk.

That is, this is based on the following study results. 6th
The figure shows how the intensity of the address signal from the address pit changes with the length of the uneven pit when the depth of the information track is constant at 2/8 and the reproduction conditions are constant. Further, FIG. 6 shows how the address signal intensity from the address pit portion changes with the uneven pit width dimension. As can be seen from FIGS. 6 and 7, the address signal strength C of the uneven pit d at the innermost circumference (45osn) of the disk D
The address pit width dimensions at the outermost disk circumference a, which is equal to , are d' and d in the pit. In other words, the change in address signal intensity due to the change in pit length in the disk radial direction is controlled to a constant level by continuously changing the pit width in correspondence with the length of the pit.

EXAMPLE Hereinafter, one embodiment of the present invention will be described based on the drawings. FIG. 1 is a perspective view of a specific example of a portion of an information track of an optical disk according to the present invention, in which the width d of the uneven pit 3 of the address pit portion 4 according to the address information is larger than the width of the guide groove 5. Also, the width d of the uneven pit 3 is small in the disk radial direction 100, and the width d of the uneven pit 3 is small in the outer circumferential direction (i-+
This figure shows an example in which the shape changes in the direction of becoming thicker in accordance with O), and in the direction in which it becomes thinner in the direction of the outer circumference (i→0) in b. With the configuration of the optical system shown in FIG. 5, under the following configuration conditions, that is, the emission wavelength λ of the semiconductor laser 20 is 830 nm, and the aperture lens 2
5, the aperture number is 0.53, the disk rotation speed is constant at 1100 Orp, and the address signal frequency from the address pit is 2. □MHz, and when the material of the disk substrate 2 is polycarbonate resin, the shape of the information track 6 is optimally set to the following values.

The depth dimension of the information track is 6Q nm to 70 nm (this corresponds to an optical path length of λ/8). Guide groove 5 width dimension is 0.65 μm NO, 85 μm or 0.3/jm
~0.6 μm0 The width d of the uneven pit 3 is 0.6 at the disk inner circumferential position (φso mm) as shown in FIG.
μm, the uneven pit width dimension corresponding to the disk radial position is continuously changed along either the curve ■ which becomes 0.3 μm at the outer circumferential position (φ120 m) or the curve ■ which becomes 0.7 μm. ing.

Fig. 2 is a diagram showing the setting value of the width of the uneven pit with respect to the position in the disk radial direction, and is calculated from Figs. 6 and 7 so that the address signal intensity from the uneven pit at the position in the disk radial direction is constant. It is something that A recording member element in which at least one of refractive index and absorption coefficient changes by irradiation with a laser beam on a disk substrate 2 on which information tracks consisting of such numerical values are formed spirally or concentrically over the entire surface at a predetermined track pitch P. For example, Te
As a result of recording and reproducing with approximately 12 Qnm of Te0x (0 < A constant level of amplitude was also obtained at each position. Further, the tracking signal intensity from the guide groove and the signal intensity recorded in the guide groove were stable and unchanged from those of the conventional guide groove. The above-mentioned results show that similar effects were obtained whether the uneven pits were made thicker or smaller from the inner circumferential position of the disk toward the outer circumferential position. Further, although the above example is a case where the information track has a depth of λ/8 suitable for the far field method, an optimum value exists even when the depth is λ/4.

Effects of the Invention As described above, the optical information recording disk carrier of the present invention uses a simple means to continuously change the uneven pit width dimension of the address pit portion of the information track in the disk radial direction. Since the address signal intensity amplitude from the address pit can be partially detected with respect to the disk radial position, the recording capacity can be improved! The information on the information track can be stably read out without decrementing the number of addresses and with a simple address reproducing circuit, which has great practical effects.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a main part of an information track of an optical information recording/reproducing disk carrier according to an embodiment of the present invention, and FIGS. 2 and 3 are top views of a conventional optical information recording/reproducing disk. FIG. 4 is a diagram showing the configuration of an optical system in an optical recording/reproducing device and the configuration of an optical information recording/reproducing disk carrier; FIG. 6 is an address pit section. Figure 6 is a characteristic diagram showing the change in the length dimension of the uneven pit versus the address signal strength, Figure 6 is a characteristic diagram showing the change in the width dimension of the uneven pit versus the address signal strength, and Figure 7 is the diameter position of the disk carrier. It is a figure which shows the setting value of the width dimension of the uneven|corrugated pit with respect to FIG. 2... Disc substrate, 3... Uneven pits, 4... Address pit portion, 6... Guide groove, 7... Recording member . Name of agent: Patent attorney Toshio Nakao and one other person
1 a
2--1 Almost skating base release 3--rvo pit Fig. 2 Fig. 4 Fig. 5 Concave pi

Claims (4)

[Claims] (1) A recording member whose refractive index or absorption coefficient changes by laser beam irradiation is attached onto a disk substrate having an address pit portion consisting of uneven pits corresponding to address information and an information track having a guide groove. In a disc carrier for optical information recording and reproducing, the width dimension of the address pit portion of the information track, which is composed of uneven pits corresponding to address information, is continuously different depending on the radial position of the disc carrier. 1. An optical information recording and reproducing disc carrier, characterized in that an information track is formed. (2) The optical information recording/reproducing disc carrier according to claim 1, wherein the length l of the concave and convex pits in the address pit portion satisfies l≦w with respect to the laser beam spot diameter w. (3) The optical information recording/reproducing disc carrier according to claim 1 or 2, wherein the recording member is made of TeO_x (0<x<2) whose main component is Te (tellurium) low oxide. . (4) The address pit portion of the information track and the guide groove both have an optical path length dimension of around λ/8 (λ is the laser wavelength) or around λ/4, or 4. The optical information recording/reproducing disc carrier according to item 3.