JPH0427610B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to disk recording and reproduction in which information is recorded and reproduced concentrically or spirally using a recordable and reproducible disk-shaped recording medium (hereinafter referred to as a disk). It is related to the device.

Conventional configuration and its problems As a high-density information reproducing device using a disk,
Video disks, PCM audio disks, etc.
Although it is being commercialized as a playback-only device, recently many disk materials and devices that can easily record and play back, such as TeOx-based disk materials, have been proposed. , it is expected to be applied to data files, and has entered the stage of practical application.

Generally, in order to stably record and reproduce high-quality information on such discs, a type of guide track called pregroove 1 is provided on the disc in advance, as shown in Figure 1, and information is recorded on this guide track. Information is recorded by applying a light beam modulated by information to form an information pattern 2. 3 is a recording material, and a TeOx thin film or the like is deposited on a base material 4. The reason why a pregroove is necessary is to prevent the center of the information track from shifting due to repeated insertion and removal of the disk, causing the spiral track to become discontinuous, and to prevent the pitch unevenness of the concentric track from increasing. This is to simplify the feed mechanism by using a track following servo.

The conventional method of recording information is as described above.
Since information is recorded or reproduced by condensing a light beam onto the pregroove, there is a problem in that less than half of the area of the recording material is used.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and an object of the present invention is to provide a disk recording and reproducing apparatus that can make maximum use of the surface of a recording material.

Structure of the Invention In order to achieve the above object, the disk recording and reproducing apparatus of the present invention is a disk recording and reproducing apparatus that records and reproduces information using a disc-shaped recording medium that is capable of recording and reproducing and on which a recording guide track is recorded in advance. a synchrotron radiation source, a modulation circuit that modulates the output of the synchrotron radiation source, an optical system that guides the output light of the synchrotron radiation source to the surface of the disk-shaped recording medium and its reflected light to a reflected light detector; a focus servo circuit for accurately focusing the output light on the surface of the disc-shaped recording medium using the output of the reflected light detector;
A tracking servo circuit for accurately following the recording guide track and a switching means for switching the polarity of the tracking servo circuit are provided, and when recording information, the polarity of the tracking servo circuit is switched. , the recording of information on the recording guide track and the recording of information in the area between the recording guide tracks can be switched.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, the principle of the present invention will be briefly explained using FIG. a to c are explanatory diagrams when focusing on T on the pregroove, a' to c' are the area between the pregroove
This is an explanatory diagram when condensing light onto T', where A and A' are the disk surfaces, B and B' are the condensing lens and the incident light beam,
C and C' indicate the field distribution intensity of the reflected light on the detectors D and D', and E and E' indicate the direction in which tracking should be corrected when each state is reached. Since a and a', and c and c', are the states when shifted to the track edge side in the same direction, the field distribution of reflected light indicated by a, a' or c, c' is the same. . However, since the direction of the track to be focused is opposite between T and T', by switching the tracking polarity, it is possible to focus the light on T on the pregroove or on the area T' between the pregrooves. It is something that can be done.

In this case, the conditions for stabilizing the tracking servo are to make the width of the pregroove T and the width of the region T' between the pregrooves almost the same, and to adjust the height of the pregroove to the wavelength of the incident light. It is necessary to prevent λ from being an integral multiple of λ/4. This is because the fairfield distribution when the pregroove height is an integer multiple of λ/4 is symmetrical, as shown by b and b', no matter where it is on the track edge.
This is because the direction of tracking cannot be obtained even if the difference from D2 is taken. In the illustrated example, T≒T′≒
A disk of 0.8 μm and a pregroove height of approximately λ/8 is used.

When recording information between pregrooves in this way, depending on the quality of the playback signal required,
Interference between signals can be reduced by erasing the previously recorded information pattern on the pregroove by performing direct current overwriting recording. For example, if the playback signal is greatly affected by crosstalk, such as with a video signal, this can be resolved by erasing the information pattern on the pregroove by overwriting before recording, although the density remains the same as with the conventional method. , it can be used twice. In addition, in the case of information that is relatively unaffected by crosstalk, such as digital signals, there is no need to erase information on the pregroove or information recorded between the pregrooves, so double density recording is possible. It is possible.

Next, one embodiment of the present invention will be described using FIG. 3. Reference numeral 5 denotes a disk, which has a pregroove structure similar to the conventional example shown in FIG.
The tracking pitch of the pregroove is approximately 2 μm. Reference numeral 6 denotes a disk motor, which rotates the disk 5 at a specified rotation speed. Reference numeral 7 represents a radiation light source, and a high output semiconductor laser or the like is used. The output light of the laser is transmitted through a lens 8, a prism 9, a λ/4 plate 10, a tracking mirror 11,
The light is focused on the recording surface of the disk 5 by the objective lens 12a attached to the focusing element 12, and information is recorded or reproduced.

The reflected light of the focused luminous flux follows the opposite path,
Objective lens 12a, tracking mirror 11,
The reflected light that passes through the λ/4 plate 10 and enters the prism 9 again, passes through the λ/4 plate 10 twice, has an optical path changed to the half mirror 13 side, and the reflected light from the half mirror 13 is passed through the condenser lens. 14 and is focused on a tracking detector 15. This tracking detector 15 is composed of, for example, a pin diode divided into two parts, focuses light around the boundary line, converts the far-field pattern into an electrical signal, and can detect the amount of track deviation of the light incident on the disk. It's becoming like that.

The transmitted light of the half mirror 13 passes through a condensing lens 16 and a knife edge 17, and is condensed onto a focus detector 18. This focus detector 18 is also composed of a pin diode divided into two parts, and can detect the focal shift of the disc incident light by the difference in the output of the two pin diodes. Via a circuit 21, the focusing element 12 that moves the objective lens 12a up and down is controlled, thereby forming a focus servo.

22 and 23 are differential amplifiers, to which the two outputs of the tracking detector 15 are input with opposite polarities. Therefore, the differential amplifiers 22, 23
The output signals of are in opposite phases to each other. A switch circuit 24 outputs one of the outputs of the differential amplifiers 22 and 23 to an attenuator 25 at the subsequent stage, drives and controls the tracking mirror 11 via a drive circuit 26, and operates a tracking servo loop. It consists of This switch circuit 24
By switching, it is possible to record information on the pregroove or record information in the area between the pregrooves with a simple operation. Although not shown, when the output of the tracking servo circuit is fed back to the feed motor that moves the optical system in the radial direction of the disk 5, the polarity of the feedback signal changes with respect to the feeding direction of the disk 5. It is necessary to match the polarity to avoid this.

27 is a modulation circuit for the radiation light source 7 such as the semiconductor laser, and the output of the adder or gate circuit 28 of the recording information signal from the S terminal and the signal from the command device 32 modulates the semiconductor laser which is the radiation light source 7. This is a circuit for modulating the power of.

29 is a head amplifier and demodulation circuit for detecting and demodulating recorded information; generally, a signal obtained by adding the outputs of two pin diodes of the focus detector 18 is used to read out an information signal based on the pit shape, and performs FM demodulation. However, the output of the tracking detector 15 may be added as necessary.

Reference numeral 30 denotes an address signal detection circuit, which supplies the address signal of the pregroove track to the command device 32 from the output of the head amplifier to obtain position information of the track to be recorded or reproduced. On recordable and reproducible discs, this address signal is often recorded in advance at the same time as the pregroove, and is used for high-speed retrieval of track positions. Therefore, even when recording information on the pregroove or in the area between the pregrooves, it is desirable that this address signal undergoes no change as much as possible, so the command device 32 At the signal recording position, a signal for restricting additional recording or erasure of information is output to the modulation circuit 27.

Reference numeral 31 denotes a keyboard or an external control device, which is used for recording information, specifying a playback mode, and inputting search address information according to the user's wishes.

In addition, when recording information on a track between pregrooves, the command device 32 outputs a signal for erasing information on the pregroove, or outputs a polarity switching signal for the tracking servo, as necessary. It also outputs truck jump signals for various trick plays, etc.

Here, the attenuators 20 and 25 in the focus servo and tracking servo system
is a circuit for correcting the difference in output light power between recording and reproducing, and always providing stable recording or reproducing operation to each servo system.

In this embodiment, a method has been described in which the tracking polarity is switched by switching the outputs of the two differential amplifiers 22 and 23 with the differential amplifier inputs of the tracking error detection stage switched. This can also be realized by replacing the input itself with a switch means, or by providing a path passing through the inverting amplifier and a path not passing through the inverting amplifier in the tracking servo circuit and switching between these paths. Furthermore, this can be similarly achieved by switching the polarity of the tracking element.

FIG. 4 is a perspective view illustrating the recording state of the disc 5, where a shows an example in which information pits are recorded on the pregroove as in the conventional example. In b, after erasing the information on the pregroove, other information is recorded in the area surrounded by the pregroove, and is useful for recording information such as video signals where crosstalk with the information on the pregroove is a problem. This is an example of recording, and one disc 5 can be used twice. Information is erased by applying modulation to the modulation circuit 27 of the radiation light source 7 using direct current or at a frequency higher than the highest frequency of the recording signal and overwriting the information. Figure c is an example in which signals are recorded on both tracks on the pregroove and in the area surrounded by the pregroove.This is an example of a digital signal that does not affect the demodulated signal much even if there is some signal crosstalk. By recording in this manner, double density recording becomes possible.

In the above embodiment, the case of a disc on which rewriting is difficult has been explained, but the present invention is also an effective means for improving the information recording density of a disc on which rewriting is possible.

Furthermore, as shown in FIG. 4b, when erasing the information pattern on the pregroove by overwriting direct current information, even if the output of the radiation light source 7 is not sufficient, the rotation speed of the disk motor 6 may be changed. By lowering it as necessary, the amount of recording light can be increased in an equalizing manner, and the erasing effect by overwriting can be made more complete.

Effects of the Invention As explained above, according to the present invention, when recording and reproducing information on a disc having a pregroove, by switching the polarity of the tracking servo of the device, tracks on the pregroove and surrounded by the pregroove can be tracked. Because information can be recorded on both the top and the disk, only a small amount of circuitry is added to conventional equipment, allowing reuse or double-density recording, thus reducing equipment and disk costs per unit of information. This can be reduced by approximately half.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the main parts of a disk cut along the radial direction, FIG. 2 is a diagram explaining the principle of tracking error detection, and FIG. 3 is a circuit of a disk recording/reproducing apparatus according to an embodiment of the present invention. block diagram,
FIG. 4 is a perspective view for explaining the recording state on the disk. 5... Disc, 6... Disc motor, 7
... synchrotron radiation source, 8 ... lens, 9 ... prism,
10...λ/4 plate, 11...Tracking mirror, 12...Focusing element, 13...Half mirror, 14...Condensing lens, 15...Tracking detector, 16...Condensing lens, 17
... Knife edge, 18 ... Focus detector, 19 ... Differential amplifier, 20 ... Attenuator, 21 ... Drive circuit, 22, 23 ... Differential amplifier, 24 ... Switch circuit, 25 ... Attenuator, 26...drive circuit, 27...modulation circuit,
29...Head amplifier, 30...Address detection circuit, 32...Command device.

Claims (1)

[Scope of Claims] 1. A disk recording and reproducing device that records and reproduces information using a disc-shaped recording medium that is capable of recording and reproducing and on which a recording guide track is recorded in advance, which comprises a radiation light source and an output of the radiation light source. a modulation circuit for modulating; an optical system that guides the output light of the radiation light source to the surface of the disc-shaped recording medium and its reflected light to a reflected light detector; A focus servo circuit for accurately focusing light on the surface of a shaped recording medium, a tracking servo circuit for accurately following the recording guide track, and a switching means for switching the polarity of the tracking servo circuit. and a configuration in which recording of information on the recording guide track and recording of information in an area between the recording guide tracks can be switched by switching the polarity of the tracking servo circuit when recording information. Disc recording and playback device. 2. When recording information in the area between the recording guide tracks, at least if the information is recorded on the adjacent recording guide tracks, the information on both adjacent guide tracks is directly transmitted to the modulation circuit of the radiation light source. 2. The disk recording and reproducing apparatus according to claim 1, wherein the information pattern is recorded after being erased by modulating the recording signal at a frequency higher than the highest frequency of the recording signal and performing overwriting recording. 3. When erasing the information pattern on the recording guide track using a disk-shaped recording medium on which a recording guide track and a track address signal are recorded at least once per revolution, the area in which the address signal is written is 3. A disk recording and reproducing apparatus according to claim 1, wherein the modulation circuit is configured to limit the overwriting operation so as to stop the overwriting operation. 4. The disk recording and reproducing apparatus according to claim 2, wherein the number of rotations of a disk motor that rotationally drives the disk-shaped recording medium is reduced as necessary when erasing the information pattern by overwriting. 5. The disk recording and reproducing apparatus according to claim 1, wherein recording and reproducing are performed using a disk-shaped recording medium in which the width of the recording guide track and the width of the area surrounded by the recording guide track are approximately equal.