JPS61133062A - Optical disk - Google Patents

Abstract

PURPOSE:To improve the accuracy when the position start end detection in the track direction is retrieved at a high speed by forming on a specific recording medium a rotation start end detection mark for detecting rotation of an optical disk and an address start end detection mark for detecting the position of the address area on each track. CONSTITUTION:The recording medium is formed with metal or alloy for forming the crystal structure different from an equilibrium phase at a room temperature by quenching it in the solid state at a high temperature. On the optical disk 2 the address start end detection mark 3 for detecting the position in the address area on each track is formed in the circular arc of the same angle as that in the address area 1 of an index area 7. In the area 7 the rotation start end detection mark 5 for controlling the rotary phase of a disk motor for rotating the optical disk is formed in the track direction with an uneven phase structure. Thus the rotation start end position, address start end position and sector start end position can be stably detected at high speed retrieval.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to the structure of an optical disc used in an optical recording/reproducing device such as a video disc.

[Background of the invention]

As an optical recording/reproducing device, for example, an optical disc coated with or vapor-deposited with a photosensitive material is rotated, and the optical disc is irradiated with a minute spot of light from a laser light source, etc., which is focused to a diameter of 1 μm or less, and the optical output intensity is measured. By modulating the recording signal, it is possible to record video signals, digital signals, etc. in real time as refraction multiple changes such as phase changes due to unevenness, changes in light and shade, and changes in reflectance and transmittance due to hole formation etc. on the optical disk. An apparatus has been proposed that is capable of reproducing recorded information by detecting changes in optical characteristics. In such an apparatus, in order to achieve high recording track density and partial recording, it has been considered to form groove-shaped guide tracks in advance on the optical disk. In order to search for an optical disk having such groove-shaped guide tracks, address information is required for each track. This address information can be preformed together with the grooved guide track. When recording information on such an optical disc with a guide track in which address information is provided for each track, it is necessary to control so that information is not recorded in the address area of each track. In addition, when playing back a track and reading out information, it becomes necessary to distinguish between the address area and the information area.In order to distinguish the 0 address signal from the information signal, a completely different signal pattern is inserted into the track. It is also possible to extract the address signal from the signal. However, in this method, if the frequencies of the address signal and the information signal are close, it becomes difficult to separate the two signals. Furthermore, when performing a track search by transporting minute spot light at high speed, detection of the start end of the address area becomes unstable, so this is not an appropriate method. It becomes necessary to input multiple address signals into the truck for even faster searching. Even during high-speed searches, it is necessary to reliably detect the start end of such an address area and reproduce the address1.
The address information is arranged in the radial direction of the disk in an arc shape forming a certain angle with respect to the center of the disk. This arc-shaped part is placed in a part other than the information track area, for example, the start end detection mark (
index mark). If this index mark is formed as the same groove structure as the groove-shaped guide track, the position of the address area can be accurately formed at the same time as the stamper of the disk. Further, a rotation start position mark is required on the optical disc in order to match the phase of the information signal with the motor that rotates the optical disc. Furthermore, when recording digital signals on such an optical disc, the track may be divided into several sectors for recording. In such a case, a sector mark indicating the starting position of each sector is also required.

The above-mentioned matters are described in Japanese Patent Application Laid-open No. 172550/1983.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical disc that can accurately detect the start end of a track direction in an optical recording/reproducing apparatus even during high-speed searching.

[Summary of the invention]

The present invention provides an optical disc having concentric or spiral tracks and equipped with a recording medium, including a rotation start end detection mark for detecting the rotation of the optical disc, and an address mark for detecting the position of the address area of each track. The optical disc is characterized in that the start edge detection mark is formed with an uneven phase groove structure, and the recording medium is made of a metal or an alloy that forms a crystal structure different from an equilibrium phase at room temperature by rapid cooling from a high temperature in a solid state. .

The recording medium of the present invention includes, for example, silver as a main component, an alloy containing 30 to 46% by weight of zinc, and 6 to 10% by weight of aluminum, or steel as a main component.

Alloys containing 10 to 20% by weight of aluminum, 21 to 30% by weight of gallium, and 16 to 35% by weight of tin; alloys containing gold as a main component and 2.5 to 5% by weight of aluminum; gallium in these alloys; 0.1-3% by weight, 1 indium
．． 5-10% by weight.

NiO, 01-20% by weight, Fe0.01-10% by weight
It is composed of an alloy containing one or more of the following.

(Embodiment of the Invention) Fig. 1 shows an embodiment of the structure of an optical disc of the present invention. Fig. 1a shows a plan view of the optical disc. Such a disc mainly records digital signals. One track is laminated to four sectors S.
, ~S4. This disk has two address areas 1 on each concentric track, and an address start detection mark (address mark) 3 is formed on the circumference of the optical disk within an arc having the same angle as the address area.

4 is a sector start end detection mark. In the case of Figure 1, 4
Since it is divided into two sectors, marks are formed at four locations. 5 is a rotation start end detection mark. This is used to control the rotational phase of the disk motor that rotates the optical disk. In this way, the optical disc is divided into an information signal track area (including an address signal area) 6 and an index mark area 7. FIG. 1 shows a cross-sectional view of the index mark area 7 in the direction along the track. The groove structure of such an index mark is shown in FIG. are arranged in the radial direction. By doing so, index marks can be formed at accurate positions at the same time using the same process as cutting the guide groove tracks of the optical disc. Therefore, an enlarged view of the portion 10 where the index marks 3, 4.degree. 5 of FIG. 1 are lined up is shown in FIG. FIG. 3a shows an example in which the index mark 8 is formed as a pit 11 having unevenness in the track direction. 3rd@b is an enlarged view of 10 when three index marks are arranged in a row.

In this case as well, in order to stably detect the index mark, which forms a pit groove within the arc of angle α necessary for starting edge detection, even during high-speed retrieval, the information signal track area 6 must be A detection system for detecting the index mark area 7 is required separately from the laser light source for reading. However, it is not necessary to narrow down the light beam to each track of the index mark 8, and the purpose of starting edge detection can be achieved by detecting only the change in reflectance of the index mark 8 as a whole. Therefore, an inexpensive incoherent light detection system using a light emitting diode and a phototransistor can be used. FIG. 4 is a diagram showing an optical recording/reproducing apparatus provided with an index mark area detector. The light driven by the laser beam drive circuit 12 passes through the aperture optical system 13 and is irradiated onto the optical disk 2 by the aperture lens 28 to read out the signal from the information track area 6. The reflected light from the optical disk 2 is transmitted to the photodetector 14. The signal is reproduced using Reference numeral 15 denotes an address reproducing circuit that reads out only the address signal from the reproduced signal. 1
6 is a disk motor that rotates the optical disk, and 17 is a linear motor that moves the optical disk 2 in the radial direction for searching. The index area 7 is detected using a photodetector 18 using a light emitting diode and a phototransistor, and is input to a signal processing circuit 19. The reproduced rotation start position mark 5 synchronously controls the disk motor 16, and the address start position mark 3 provides the 1 address reproducing circuit 15 with timing for reading the address. Further, the sector start end detection mark 4 controls the timing of reproduction and recording of the information track of each sector. The circuit configuration of the signal processing circuit 19 is shown in FIG. 5. Incoherent light emitted from the zero light emitting diode 2o is emitted onto the index mark area 7 on the optical disk 2. When the index mark is irradiated with light, the amount of reflected light changes, and the photodiode 21 detects the change. The detection signal is inputted to an amplifier 22 and then inputted to a bandpass filter 23 in order to eliminate the influence of changes in light amount due to surface play of the optical disc 2. Further, a comparator 24 converts the detection signal into a pulse. Here, FIG. 6 shows waveforms at various parts of the circuit configuration. FIG. 6a shows a sectional view of the index mark area 7 in the same circumferential direction. When light falls on the index mark, it is scattered, so the output of the phototransistor has a small amplitude as shown in FIG.

FIG. 6C shows the waveform of the comparator output G. The index pulse C output from the comparator 24 is input to the retriggerable multivibrator 25, which outputs a signal with a pulse width of T<t<2T from the rising edge of the pulse (6th@d), where T is the 6th As shown in Figure C, the periodicity is shown when index marks are continuously formed. This output is input to the D-flip-flop 26,
It is latched by the index pulse C clock mentioned earlier and is output to the Q8 terminal (Fig. 6e).

Furthermore, it is input to the next stage D-flip-flop 27, and the output shown in FIG. 6f is obtained at the output terminal Q2.

Then, the AND circuit 3 outputs the AND output of the output c-e-f.
0 and output as a sector start detection signal (Fig. 6g). In addition, the AND circuit 31 obtains a logical product output of the outputs c's and f, and generates a rotation start detection signal (h in FIG. 6).
It is output as .

Furthermore, the AND circuit 32 outputs the AND output of the output c-e-f.
The address start end detection signal (FIG. 6i) is obtained by using the following method.

As described above, by forming index marks on the inner circumferential portion of the optical disc 2 using the same process as the guide grooves in the information track area, it is possible to easily obtain a stable information position detection signal even during high-speed retrieval.

These index marks can not only stably detect information positions, but also control the timing of track jumping during retrieval.

For example, when information is recorded in the form of a spiral track, it becomes necessary to repeatedly reproduce tracks with the same circumference. In such a case, it is necessary to jump the track every rotation.

The timing of this jumping may be determined by detecting the rotation start position detection mark 5 described above. However, a time delay is required between detecting the rotation start point and activating the pickup of the optical head that reads information to perform jumping. Therefore, as shown in Fig. 7, the mounting position of the photodetector 18 that detects the rotation start position detection mark 5 is shifted by an angle β.By doing this, the information of one track can be stably reproduced from the start end of the address signal. You can do jumping like this. As shown in FIG. 7, the diaphragm lens 28 of the optical head starts jumping earlier by an angle of β and performs the jumping in the jumping section 29, so that information can be stably reproduced from the beginning.

FIG. 8 shows waveforms at various timings during jumping. FIG. 8a shows the detection pulse waveform of the index mark, No. 8@b shows the reproduced address signal at the information start end, and FIG. 8C shows the rotation start end detection pulse, where the index mark photodetector 18 is attached. is shifted by β, so the actual timing is as shown in FIG. 8d.

Jumping is activated by the signal d. FIG. 8e shows the amount of movement of the optical head in the disk radial direction. By doing this, the jumping is completed in section 29, so the optical head can stably reproduce information from the beginning.

When information is to be recorded on both sides of the optical disc 2, it becomes necessary to detect the front and back sides of the disc.

Index marks can also be used effectively in such cases. Index marks with different groove structures are formed on the front and back sides. For example, by making the number or width of marks different, it is possible to detect the front and back sides using a method similar to the circuit configuration described above. Further, by forming different index marks on different discs, the type of disc can also be identified.There is also an advantage in detecting the front and back sides and types of discs using six index marks. There is no need to illuminate a laser light source to read information tracks and then search for tracks containing this information. Furthermore, if different reproducing power and recording power are required for each optical disc, the optimum optical power can be selected for each disc without irradiating it with laser light.

〔Effect of the invention〕

According to the present invention, by using index marks, the rotation start position, address start position, and sector start position can be stably detected even during high-speed searching. Furthermore, since the index mark can be formed when cutting the guide groove or information pit of the optical disc, it is possible to use the same accurate process as the conventional method. Furthermore, it is possible to identify the occurrence of the timing of track jumping activation and the type of the front and back of the disc without using a laser light source.

[Brief explanation of the drawing]

FIG. 1a is a plan view showing an outline of an optical disc according to an embodiment of the present invention, b is a cross-sectional view taken along the same track direction, and FIG. 2a is a
3 is an enlarged perspective view of the same main part, b is an enlarged plan view of the same, FIG. 3a is an enlarged perspective view of the same main part, b is an enlarged plan view of the same, and FIG. Block diagram, 5th
WI is a block diagram of the main part, FIG. 6 is an explanatory diagram of the same operation, and FIG. 7 is an explanatory diagram of the operation showing the processing system for the output from the re-detector. 1... Address area, 2... Optical disk, 3... Address start end detection mark, 4... Sector start end detection mark, 5
... Rotation start end detection mark, 6... Information signal track area, 7... Index mark area, 2o... Light emitting diode, 21... Phototransistor. ＼Kuniji (b) Pavilion 2 (α) (α9 (b)

Claims (1)

[Claims] 1. In an optical disc having concentric or spiral tracks and equipped with a recording medium, a rotation start end detection mark for detecting one rotation of the optical disc and the position of the address area of each track are provided. The address start detection mark for detection is formed with an uneven phase groove structure, and the recording medium is made of a metal or alloy that forms a crystal structure different from an equilibrium phase at room temperature by rapid cooling from a high temperature in a solid state. An optical disc featuring 2. An optical disc according to claim 1, characterized in that the rotation start end mark and the address start end detection mark are formed with a phase groove structure that allows it to be identified that they are different marks. 3. An optical disc according to claim 1, characterized in that rotation start position marks of different phase groove structures are formed on the front and back sides of the optical disc to detect the front and back sides of the disc. 4. An optical disc according to claim 1, characterized in that a rotation start position mark having a phase groove structure that differs depending on the type of optical disc is formed.