JPH04324136A - Optical disk - Google Patents

Abstract

PURPOSE:To prevent double transfer by providing intermittent grooves disposed with mirror parts synchronized with sample marks at 0.25 to 0.75mm width on the inner and outer sides of a track region. CONSTITUTION:The groove regions 4, 5 formed with the mirror parts 3 of microsections respectively on the inner and outer peripheries are provided in proximity to the track region in correspondence to the sample marks 2. The groove regions 4, 5 are so formed as to be discontinuous with the mirror parts 3 of the microsections in-between and, therefore, the deviation in the sample marks by the molten resin material injected into metallic molds is supported by the groove regions 4, 5 and the double transfer is prevented. The gases generated from the resin material are simultaneously discharged smoothly along the sample marks 2 by passing the mirror parts constituted of the intermittent grooves. Since the track region is not affected by these gases, the resin packing rate is increased.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recordable and reproducible optical disc and/or a partial ROM optical disc having a small pit recording density and having a portion exclusively for reproduction.

0002

2. Description of the Related Art Continuous servo systems and sample servo systems are known as tracking systems for optical discs on which information can be recorded. The continuous servo method is a method that has been developed in the past, but the sample servo method has recently been put into practical use because of its good tracking stability. In this sample servo method, sample marks (pits) for tracking are provided here and there on the track, and the magnitude of the reflected light from a pair of pits distributed left and right from the center of the track is compared to determine the deviation from the center of the track. Tracking is performed while detecting. By the way, when such an optical disk is injection molded, the resin tends to move easily, resulting in double transfer. In order to prevent this, Japanese Patent Application Laid-Open No. 63-211137 discloses that a plurality of grooves or pits are provided on the inside and outside of the track area having the sample mark and close to the track area. Optical discs have been proposed that prevent double transfer of marks and obtain good tracking signals. Specifically, resin temperature 340
℃, mold temperature 90℃, injection speed 100mm/sec, holding pressure 100kg/cm2, groove areas with a width of 0.1mm or more are provided on the inner and outer peripheries of the sample mark area. The groove area acts as an anchor effect during injection molding to prevent double transfer from occurring.

0003

[Problems to be Solved by the Invention] However, when a groove area is provided on the outer periphery, it is possible to prevent the occurrence of double transfer, but the gas generated from the resin during injection molding is This gas makes it difficult to vent the gas smoothly, and this gas makes it impossible to improve the resin filling rate beyond a certain level, and the surface accuracy of the mirror part provided in areas other than the pits is affected. cannot improve. If optical discs etc. have poor flatness,
Diffracted light due to large birefringence and unevenness occurs on the surface, deteriorating the CN ratio (ratio of signal level to noise level), and as a result, reliable recording and reproduction cannot be performed. An object of the present invention is to obtain an optical disc that solves these problems.

0004

[Means for Solving the Problems] In order to solve the above-mentioned problems, an optical disc according to the present invention has mirror portions synchronized with the sample marks inside and outside the track area having the sample marks, close to the track area. The intermittent grooves were arranged with a width of 0.25 mm to 0.75 mm.

[0005]

[Function] According to the optical disc according to the present invention, the intermittent grooves have an anchor effect when the disc is injection molded, and the gas generated from the resin material passes through the mirror portion composed of the intermittent grooves to mark the sample. It is smoothly exhausted along the

[0006]

Embodiments An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a plan view of a substrate of an optical disk according to the present invention, and FIG. 2 is a partial plan view of the optical disk according to a first embodiment of the present invention. Here, the optical disc 1 is 3.5 inches or 5.25 inches according to the ISO standard, and a sample servo system is adopted. For example, in the case of an ISO standard 3.5-inch disc, the number of sample marks 2 for servo is 1672 (22 sectors x 76
blocks) are arranged radially.

Corresponding to this sample mark 2, groove areas 4 and 5 are provided close to the track area having this sample mark 2, in which minute sections of mirror portions 3 are formed on the inner and outer peripheries, respectively. This mirror portion 3 is formed so that the groove regions 4 and 5 are discontinuous. The ratio of the groove regions 4 and 5 to the mirror portion 3 is approximately 9:2. FIG. 2 shows the sample mark 2 and the groove area 4 on the outer periphery, and the mirror portion 3 synchronized with the sample mark 2 is arranged on an extension line linearly arranged in the radial direction (
(hereinafter referred to as linear arrangement). Here, groove area 4
The pitch and track width of the grooves 41, 42, and 43 that form the grooves need only be a certain level or more, so the pitch and track width are the same as those of the sample mark (pit) 2, which is usually easy to manufacture.
For example, the pitch is 1.5 μm and the width is 0.5 μm. Also,
The depth is assumed to be λ/4 (λ is the wavelength of the laser beam). Note that sample mark 2 and groove area 5 on the inner circumference
are also provided in the same way as in FIG.

The optical disc 1 has T on the surface of a disc substrate made of a transparent synthetic resin material such as polycarbonate.
A laminated film of a dielectric film such as aOx or SiNx and a metal film such as Al or TbFeCo is deposited and a protective film is laminated. Data etc. are recorded in the area having the sample mark 2. Groove regions 4 and 5 with a width of 0.5 mm are provided on the inner and outer peripheries, respectively, close to the region having the sample mark 2. The width of the groove regions 4 and 5 is most preferably around 0.5 mm, but may be in the range of 0.25 to 0.75 mm. This is because, as can be seen from the graph in FIG. 3, it has been experimentally confirmed that the width of the groove region greatly contributes to moldability. Note that 6 indicates the center of the virtual track.

The disk substrate has the groove area 4
, 5 and the sample mark 2 by injection molding using a mold having a predetermined shape. The specific injection conditions at this time were a resin temperature of 330° C., a mold temperature of 120° C., an injection speed of 70 mm/sec, and a holding pressure of 80 kg/cm 2 . Here, in the injection molding method, the groove region 4
, 5 are formed so as to be discontinuous across the mirror portion 3 of minute sections, so that the deviation of the sample mark caused by the molten resin material injected into the mold can be detected in the groove regions 4, 5.
to prevent double transfer. At the same time, the gas generated from the resin material passes through the mirror section consisting of intermittent grooves and is smoothly exhausted along the sample mark 2, increasing the resin filling rate and eliminating the effects of the gas. The surface precision of the provided mirror portion 3 can be improved. At the same time, it is also possible to improve the accuracy of mechanical properties by lowering the mold temperature.

Another embodiment of the invention is shown in FIGS. 4 and 5. FIG. 4 is a partial plan view of an optical disc according to a second embodiment of the present invention, and the same parts are given the same reference numerals. In this example, the mirror part 3 synchronized with the sample mark 2 was arranged approximately at the center of the two sample mark rows (hereinafter referred to as central position arrangement), so that the molten resin material injected into the mold It flows smoothly through the mirror section composed of intermittent grooves, and the deviation of the sample mark caused by this melted resin material is supported by the groove area 4 on the radiation, thereby preventing double transfer. Further, at this time, the gas generated from the molten resin material is exhausted along the sample mark 2, thereby increasing the resin filling rate and improving the surface precision of the mirror portion 3, as in the first embodiment.

FIG. 5 is a partial plan view of an optical disc according to a third embodiment of the present invention, and the same parts are given the same reference numerals. In this embodiment, the grooves 41, 42, 43, etc. are arranged in a checkerboard pattern (hereinafter referred to as a checkerboard arrangement) so that the same effects as in the first and second embodiments can be achieved. This is what I did.

[0012] Furthermore, sample servo type SFP signal (
Double transfer can also be prevented by arranging (pit rows) with a width of 3 mm or more (hereinafter referred to as SFP signal arrangement), and at the same time, it is possible to increase the resin filling rate and improve the surface precision of the mirror portion 3. In the above embodiment, the configuration of the sample mark and groove area on the inner periphery is the same as the configuration on the outer periphery, but similar effects can be obtained by combining (12 types) as shown in Table 1 below. Of course, it is possible to perform.

[0013]

[Table 1]

[0014]

Effects of the Invention According to the optical disc according to the present invention, inside and outside the track area having sample marks,
Intermittent grooves with mirror parts arranged in synchronization with the sample marks are placed in the vicinity of the track area with a diameter of 0.25 to 0.75.
Since it is provided with a width of mm, the following effects can be achieved. ■Prevention of double transfer of sample mark ■Improvement of resin filling rate of sample mark ■Improvement of surface precision of mirror part

[Brief explanation of the drawing]

FIG. 1 is a plan view of a substrate of an optical disc according to the present invention.

[Figure 2
] A partial plan view of an optical disc according to a first embodiment of the present invention.

[Figure 3] Graph showing the relationship between groove width and formability

[Figure 4
] Partial plan view of an optical disc according to a second embodiment of the present invention

FIG. 5 is a partial plan view of an optical disc according to a third embodiment of the present invention.

[Explanation of symbols]

1...Optical disc, 2...Sample mark, 3...Mirror part,
4, 5...Groove area, 41, 42, 43...Groove,
6... Focus on virtual tracks.

Claims (3)

[Claims] Claim 1. In a recordable and reproducible optical disc that employs a sample servo system and/or a partial ROM optical disc that has a small pit recording density and that has a partial read-only section, the above-mentioned track is provided inside and outside the track area having sample marks. 1. An optical disc characterized in that intermittent grooves having a width of 0.25 mm to 0.75 mm are provided in close proximity to the area, in which mirror portions synchronized with sample marks are arranged. 2. The optical disc according to claim 1, wherein the mirror portions synchronized with the sample marks are arranged on extension lines linearly arranged in the radial direction. 3. The optical disc according to claim 1, wherein the mirror portion synchronized with the sample marks is located approximately at the center of the two sample mark rows.