JPH0711876B2 - Magneto-optical disk player - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical disk player, and more particularly to a magneto-optical disk player capable of speeding up erasing and re-recording.

[Prior Art] In a magneto-optical disk player, a magnet having a magnetic pole whose direction is perpendicular to the disk surface is arranged on one side of the magneto-optical disk, and an optical head for a magneto-optical disk (hereinafter referred to as magneto-optical disk) is arranged on the other side. It is possible to record, reproduce, and erase. The polarities of the magnets are reversed between recording and erasing.

In this type of conventional magneto-optical disc player, as shown in FIG. 2, two permanent magnets 2, 3 having different polarities are arranged on the upper surface of the disc 1, and the permanent magnets 2, 3 are recorded or erased.
Is moved in parallel above the objective lens 5 of the magneto-optical head 4, or a structure in which only one permanent magnet is arranged and the magnetism is reversed during recording and erasing, or as a magnet Although the structure is such that the polarities are reversed by using an electromagnet, only one magneto-optical head is used in each case.

[Problems to be Solved by the Invention] In re-recording in a magneto-optical disc player, the contents of the previous recording are erased and then writing is performed. However, in the conventional magneto-optical disc player described above, writing is performed while erasing. It cannot be done. Therefore, when re-recording, the entire section to be re-recorded is erased, and then writing is performed, but the erasing operation is performed by the same tracking as at the time of recording or reproduction. , Takes a long time. Therefore, re-recording takes a long time and there is a problem in high-speed access.

The present invention solves the above-mentioned problems of the prior art and makes it possible to perform writing while erasing in the case of re-recording, thereby shortening the time required for re-recording.

[Means for Solving Problems] In order to solve the above problems, according to the present invention, two sets of optical heads and rod-shaped permanent magnets that face each other with a disk in between are provided at different positions on the disk surface, and two sets. The two permanent magnets were arranged in the radial direction of the disk with the polarities reversed.

[Operation] It is possible to perform erasing by one set of optical heads and permanent magnets, and re-record on the erased portion by another set of optical heads and permanent magnets. Therefore, erasing and re-recording can be performed at the same time, and the time required for re-recording can be shortened.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings. Here, as the optical head, one is an optical head for a magneto-optical disk (magneto-optical head), and the other is a so-called DRAW.
(Direct Read After Write) optical head for write-once disc that is writable only once and cannot be erased,
That is, by using an optical head for a write-once disc (hereinafter referred to as a write-once head), recording / reproduction / erasing of a magneto-optical disc, recording / reproduction of a write-once disc, reproduction of a reproduction-only disc such as a CD (compact disc) It is possible and has achieved multi-use.

In FIG. 1, permanent magnets 12 and 14 are arranged symmetrically on the upper surface of the disk 10 in the radial direction of the disk 10.
The polarities of the permanent magnets 12 and 14 are highly opposite to that of the disk 10.

On the lower surface of the disk 10, optical heads 16 and 18 are arranged facing the permanent magnets 12 and 14, one optical head 16 is a magneto-optical head, and the other optical head 18 is a write-once head. Is used. The optical heads 16 and 18 are moved in the radial direction of the disk 10 along shafts 19 and 20, respectively. 2
Reference numerals 1 and 22 denote objective lenses.

The control circuit of FIG. 1 shows a configuration in which a magneto-optical disk is used as the disk 10, recording and reproduction are performed by a magneto-optical head 16, and erasing is performed by a write-once head 18.

The erase range instruction circuit 20 indicates the address of the erase range.
The received light signal from the magneto-optical head 16 is input to the signal reproduction circuit 22 and subjected to signal reproduction processing. The address detection circuit 24 detects an address signal from the reproduction signal. In addition, the received light signal from the write-once head 18 is sent to the signal reproduction circuit 26.
Is input to and signal reproduction processing is performed. The address detection circuit 28 detects an address signal from the reproduced signal.

The arithmetic processing circuit 30 controls the position of the write-once head 18 so that the address detected by the address detection circuit 24 and the address detected by the address detection circuit 28 match. Then, when these addresses match the addresses designated by the erase range designating circuit 20, the arithmetic processing circuit 30 drives the write-once head 18 through the erase determining circuit 32 and the drive circuit 34 to drive the write-once head 18 of the disk 10. Erase. Immediately after this, the erased address can be rewritten by the magneto-optical head 16. By performing rewriting at the same time as erasing in this way, the time required for rewriting can be shortened.

By the way, when erasing a magneto-optical disk, it is necessary to maintain a strong laser beam for heating the medium above the Curie point for a long period of time.
The ratio of the transmitted / reflected wave of the polarized light in the beam splitter is T
Even if p: Ss = 7: 3 is set, the light beam utilization efficiency is as low as about 35%, so a high-power laser is required. Therefore, when erasing with the magneto-optical head, a large output is maintained for a long time, which imposes a heavy burden on the laser. However, the write-once type head generally has a light beam utilization efficiency of about 60%.
Therefore, when this write-once head is used for erasing as in the embodiment, it exerts sufficient ability as an erasing head, lightens the load on the laser, and is efficient.

When the magneto-optical disc player shown in FIG. 1 is used for reproducing a write-once disc, reproduction is usually performed by the write-once head 18. Although it is desirable to use a write-once head for a write-once disc as described above, the magneto-optical head 16 can also be used for playback of a write-once disc, so a picture-in-picture (part of the screen Fit other screens into)
Special reproduction such as is also possible. Further, since both the magneto-optical head and the write-once head can be used for reproducing the reproduction-only disc, the special reproduction can be performed even when reproducing the reproduction-only disc.

FIG. 3 shows a configuration for outputting reproduction output, address output and the like from the magneto-optical head. This reproduction signal detection system employs a so-called differential detection method.

The laser light emitted from the semiconductor laser 50 is applied to the disk surface through the collimator lens 52, the beam shaping prisms 54 and 56, the beam splitter 58, the mirror 60, and the objective lens 62. The reflected light from the disk surface is the objective lens 62,
The light is received by the four-division photodiode 72 via the mirror 60, the beam splitter 58, the half-wave plate 64, the condenser lens 66, the polarization beam splitter 68, and the cylindrical lens 70. The received light signals of the four-divided photodiode 72 are added to the diagonal lines and input to the subtractor 74 to detect a focus error. Further, the addition signals of the diagonal lines are added by the adder 76, and the address is detected via the amplifier 78. In addition, the light transmitted through the polarization beam splitter 68 is 2
The light is received by the split photodiode 80. The light reception signal of the two-divided photodiode 80 is input to the subtractor 82, and a tracking error is detected. Further, the adder 84 performs addition, and the subtractor 84 subtracts from the output of the adder 76 to obtain an RF reproduction output. That is, differential signal detection is performed.

[Effects of the Invention] As described above, according to the present invention, two sets of optical heads and rod-shaped permanent magnets that face each other with a disk sandwiched are provided at different positions on the disk surface, and the polarities of the two permanent magnets are set. Since they are arranged in reverse, they have the following excellent effects.

(I) Erasure and re-recording can be performed at the same time, and the time required for re-recording can be shortened. That is, high speed access is realized.

(Ii) A single magneto-optical disk player can record / reproduce / erase a magneto-optical disk, reproduce / write-once a write-once disc, and reproduce a reproduction-only disc.
Multi-purpose is realized.

Also, special reproduction such as picture-in-picture can be performed.

(Iii) It becomes unnecessary to switch the permanent magnet or the electromagnet, and the operation is simplified.

(Iv) As shown in the embodiment, one is a magneto-optical head,
If the other is used as a write-once head, the magneto-optical head is used for recording / reproduction, and the write-once head is used for erasing, the write-once head with high light utilization efficiency exerts sufficient ability as an erasing head, and laser output It is efficient and effective for extending the life of the laser.

[Brief description of drawings]

FIG. 1 is a mechanism diagram and a control block diagram showing an embodiment of the present invention, FIG. 2 is a plan view showing a conventional device, and FIG. 3 is a configuration diagram of a general optical head for a magneto-optical disk. 10 …… disc, 12,14 …… permanent magnet, 16 …… optical head for magneto-optical disc, 18 …… optical head for write-once disc.

Claims (1)

[Claims] 1. A pair of optical heads and rod-shaped permanent magnets that face each other with a disk sandwiched between them are arranged at different positions on the disk surface and in the radial direction of the disk with the magnetism of the two permanent magnets reversed. , One of the two optical heads is an optical head for a magneto-optical disk, and the other is an optical head for a write-once disk, and the recording / reproducing is performed by erasing the magneto-optical disk by the head for the write-once disk. A magneto-optical disk player, characterized in that the optical head for a magneto-optical disk is used for performing.