JPH0534738B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a disc-shaped information recording medium used in video disc devices and the like.

2. Description of the Related Art Structures of Conventional Examples and Their Problems In recent years, various disk-shaped information recording media (hereinafter referred to as disks) and information recording and reproducing systems using the same have been developed and commercialized. The above systems can be broadly classified into those that can only be played back, those that can be recorded only once, and those that can be recorded and erased.
There are many recording and reproducing methods. For example, if we take an information recording and reproducing system that uses laser light, it is classified by its track shape (concentric or spiral), groove depth, width, track pitch, rotation speed, etc. can. Because there are so many types of discs, when recording or reproducing different types of discs using one information recording/reproducing system, it is necessary to determine what type of disc the disc is. For example, a video disc player uses the capacitive VHD system.
In order to identify the type of disk, etc., an unevenness is provided at the disk ejection opening of the disk storage case, and the type of disk is encoded on the unevenness. When playing a disc, the case containing the disc is inserted into the player, and only the disc is attached to the player. At that time, the player reads information about the unevenness of the disc ejection opening and determines what kind of disc it is. It is designed to read the information and play it accordingly. On the other hand, in the case of an optical information recording and reproducing system, since there is no need to store the disc in a case, it is necessary to record a mark on the disc in advance so that the type of disc can be automatically determined. Patent application 16518/1987 proposes a disk in which a mark indicating the type of disk is provided outside the information track band. By using the disc according to this proposal, it is possible to construct a system that can record and reproduce various types of discs by identifying marks recorded in advance on the disc. In particular, since the discrimination mark is formed in the same groove as the recording track, the discrimination mark can also be formed at the same time as the recording track is formed.Moreover, when an address is recorded at the time of recording track formation, Another advantage is that the positions of the discrimination marks and addresses can be formed with high precision. The disk according to the above proposal will be briefly explained below. FIG. 1 shows an embodiment of the proposed disk. In FIG. 1, reference numeral 2 denotes a recording track band having a spiral shape and a constant track pitch, and is an area in which an information signal can be recorded on the track using a laser beam or the like. Reference numeral 4 denotes a disk discrimination mark which also serves as a synchronization mark for controlling the rotational phase of the disk motor that rotates the disk. 1 is a center hole through which the disk is attached to the disk motor. 3 is an address area in which the address of each track is recorded, and the arrow indicates the rotation direction of the disk. The disc discrimination mark 4, like the information recording track 2, is formed as a groove structure during master disc recording. However, whereas the information recording track 2 forms a concentric or spiral continuous track by continuously recording with a laser beam of constant intensity over the entire circumference, the disc discrimination mark 4 records only a certain angle within one circumference. Grooves are formed intermittently by irradiating a laser beam with a constant intensity. Therefore, while the non-mark part of the discrimination mark area is an extremely smooth plane, the discrimination mark part has a groove structure, and the reflected light is scattered due to the unevenness of the surface, which can be discriminated as a difference in reflectance. Marks can be detected. Specifically, a light emitting diode and a photodetector detect the difference in reflectance between the discrimination marks on the disk and convert it into an electrical signal. Figure 2 shows changes in the reflectance of the discrimination mark portion on the disk 5, a detection signal 6 of reflected light from a photodetector, and a detection signal 7 with waveform formation.
shows. The horizontal axis shown in Figure 2 is the time axis, shown in 5.
R _H is a portion with high reflectance, and R _L is a portion with low reflectance. The discrimination mark has uneven grooves on its surface, so the reflectance is reduced. This difference in reflectance (R _H
and R _L ) are converted into electrical signals (V _H1 and V _L1 ) shown in 6 by a photodetector. The converted detection signal 6 is waveform-shaped by a waveform shaping circuit as shown in 7. The first mark among the three marks during one rotation is a synchronization mark for controlling the rotational phase of the disk motor that rotates the disk, and the disk can be identified by the falling edge of this first mark.
This is performed depending on whether there is a falling edge at t ₂ after Δt from t ₁ and whether there is a falling edge at t ₃ after Δt. That is, a certain period of time Δt from the first falling edge _t1
Disc identification is performed based on how many falling edges there are for each disc. Another example of a discrimination mark is a method in which the type of disk is encoded by the length of the interval between the first falling edge and the next falling edge.

As described above, by providing a disc identification mark in addition to the information track band of a disc, it is possible to record or reproduce information on many types of discs using a single device without having to provide separate devices for each type of disc. Further, since the disk discrimination mark is made of the same groove as the recording track, the discrimination mark can be formed at the same time as the recording track forming process.

However, the disk type determination according to the above proposal has the following problems. Discrimination marks are created by irradiating a laser beam used for recording track formation only at a certain angle during one rotation to intermittently form a groove structure, making the surface uneven and having different reflectance. Therefore, in order to identify the discrimination mark, a light emitting diode and a photodetector are used to detect the difference in the reflectance of the discrimination mark on the disk surface.For example, as shown in FIG. If there are parts 9, 9' where the reflectance has changed due to scratches etc. in addition to the disk discrimination marks 8, 8' which also serve as marks, the electric signal whose waveform has been shaped as shown in 11 will have the correct discrimination marks 12,
In addition to 12', erroneous discrimination marks 13 and 13' are detected.

If such an erroneous signal is detected, it will lead to malfunction of the device. The disc identification mark depends on the difference in reflectance, but since the reflectance can easily change due to dirt or scratches on the disc surface, it is possible that dirt, scratches, cloudiness, etc. can be mistakenly identified as the disc identification mark. There is enough sex. Although it is effective to record a disc type identification mark on a disc as described above, there is a problem in that it is prone to malfunction due to dirt, scratches, etc. on the disc surface.

Purpose of the Invention The present invention solves the above-mentioned conventional problems.
It is an object of the present invention to automatically determine the type of disk with high accuracy so that recording or reproduction can be performed on various types of disks with a single recording/reproducing device.

Structure of the Invention The present invention provides an identification mark indicating the type of one or more disks at a specific position on the inner or outer periphery of a concentric or spiral information track, and further includes a mark that is sufficiently wider than the identification mark. It is a disk with one or more disks.

In addition, in the recording and reproducing apparatus, a gate is used to generate a gate signal indicating a specific position from a second mark signal separated and detected by a separation means that detects only marks having a width equal to or larger than the second mark from the output of the reflectance detection means of the disk. The apparatus has a signal generating means, and is configured to read mark signals other than the second mark signal based on the output of the gate signal generating means and the output of the reflectance detecting means.

DESCRIPTION OF EMBODIMENTS FIG. 4 shows an embodiment of the present invention, in which reference numeral 2 denotes a recording track band having a spiral shape and a constant track pitch, and information signals can be recorded on the track using a laser beam or the like. It is an area. 1
3 is a center hole where the disk is attached to the disk motor, and 3 is an address area where the address of each track is recorded. These configurations are the same as those of the conventional example. 14-2
1 is a discrimination mark that is a feature of the present invention. In the conventional example, the discrimination mark was formed only at the position shown at 15, but in this embodiment, marks are formed at seven other positions. In particular, the mark shown at 14 is formed much wider than the other marks. This mark 14 is called a flag mark, and marks 15 to 21 are called first to seventh marks, respectively.

Reference numeral 22 in FIG. 5 shows the change in reflectance of the portion where the mark is formed. 23 indicates a detection signal of a photodetector that detects a change in reflectance. The signal waveform shown at 24 shows the case where the detection signal shown at 23 is passed through a low frequency filter, and when the voltages are compared at the potential shown at 25, only the flag mark portion 14 can be extracted as shown at 26. If a gate signal 27 for extracting the signal of only the first mark is created based on these 26 signals, only the first mark can be extracted as shown in 28. Also, as shown in 29, the second
In order to extract only the mark, only the second mark can be extracted by using a gate signal generated based on the signal shown in 26. In this way, the number of erroneous signal readings due to dirt or scratches on the disk surface, which has been a problem in the past, is reduced, and stable and highly accurate signal reading becomes possible. Here, the method of encoding the type of disk into the discrimination mark in FIGS. 4 and 5 is the same as in the conventional example. For example, as shown in this example, marks are attached to seven places in one round in addition to the flag mark, and the sixth
As shown in the figure, if up to five marks are added to one mark, (2 ⁴ ) ⁷ ways of encoding (approximately 2.7×10 ⁸ ways) are possible. As a specific usage example, the first mark is a reference signal mark for rotation synchronization of the disk motor, and the second mark is the A side (front) for TYPE1 shown in Figure 6, and the B side (for TYPE2). If the third mark is TYPE1, the disk diameter is 20cm, if the third mark is TYPE2, the disk diameter is 30cm, and if the third mark is TYPE1, the track pitch of the recording track is 1.6μm.
For TYPE2, encode as 2.5μm. As described above, according to the present invention, all kinds of discs can be encoded, and since the mark at a desired position is read using the flag mark as a reference mark, the type of disc can be determined with high accuracy.

The embodiment shown in FIG. 7 shows an example of a disk having three sets of flag marks and encoded marks in one circumference. In this way, even if one of the three pairs cannot be identified due to dust or scratches, it can be identified by reading the mark on the ground, and compared to the embodiment shown in FIG. The structure is designed to prevent malfunctions.

Effects of the Invention As described above, by attaching a mark as shown in this embodiment to a disk, it is possible to greatly reduce malfunctions caused by dirt, dust, scratches, etc. on the surface of the disk, which have been problems in the past, and to ensure stable disk operation. It has become possible to determine the type of Also, it has become possible to stably detect the synchronization mark of the disk motor. The discrimination mark according to the present invention also has the effect that it can be recorded at the same time as the recording track is formed, as in the prior art.

[Brief explanation of drawings]

Fig. 1 is a plan view showing a disk with a conventional disc discrimination mark, and Fig. 2 shows changes in the reflectance of the disc discrimination mark, changes in the detection signal by the photodetector that detected the change, and the detection signal. 3 is a diagram showing a signal detected by a photodetector when there are scratches or dust on the disk surface, and an example of a signal obtained by shaping the detection signal. FIG. 4 is a diagram showing an example of a signal obtained by shaping the waveform of the detection signal. FIG. 5 is a plan view showing an embodiment of a disk equipped with a disk discrimination mark according to the present invention, FIG. FIG. 7 is a plan view showing another embodiment of a disc equipped with a disc identification mark according to the present invention. 1...Center hole, 2...Record track band, 3...Address area, 14-21...Discrimination mark.

Claims (1)

[Scope of Claims] 1. It has a recordable or reproduction-only information track band, and has a different reflectance other than the information track band,
A first mark having a constant width in the tangential direction and the radial direction is provided, and a width sufficiently wider than the tangential direction width of the first mark is provided in a constant positional relationship with the first mark other than the first mark. 1. A disc-shaped information recording medium, characterized in that one or more second marks are provided in one circumference to serve as a reference for detecting the first mark. 2 Track shape, front and back sides, track pitch,
2. The disk-shaped information recording medium according to claim 1, wherein information indicating either the medium diameter or the like is encoded in the first mark. 3. The disc-shaped information recording medium according to claim 1, characterized in that the first mark and the second mark are a pair, and a plurality of pairs of marks are provided in one circumference. 4 Separate detection was performed using a reflectance detection means that is a combination of a light source and a photodetector fixed in correspondence with the mark position on the disk-shaped information recording medium, and a separation means that detects only marks with a width equal to or larger than the second mark from the output. It has a gate signal generating means for generating a gate signal indicating a specific position from a second mark signal, and a mark signal other than the second mark signal is generated by the output of the gate signal generating means and the output of the reflectance detecting means. A recording/reproducing device characterized by reading.