JPH0434728A - Optical disk device - Google Patents

Abstract

PURPOSE:To ensure a sufficient data transfer rate by providing a medium type discrimination means discriminating the type of a disk medium as to whether it is for recording and reproduction or for reproduction only and selecting number of revolutions of the disk medium by a drive source in response to a discrimination output to be high or low. CONSTITUTION:Medium type information discriminated by a medium type discrimination circuit 8 is fetched by a drive controller 7 to apply switching control of disk rotation number by a spindle motor 1 through a number of revolution control circuit 12 being a rotation number changeover means. When a disk medium 2 in use is for reproduction only, low speed drive is attained to a degree offering smaller face wobbling or track deflection acceleration in comparison with the case for recording and reproduction use, an inexpensive optical disk 2 for reproduction only is used and all of plural optical heads 3, 4 are used for reproduction. Moreover, in the case of the recording and reproduction optical disk 2, high speed drive is attained by utilizing the material feature. Thus, a sufficient data transfer rate is ensured.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical disk device equipped with a plurality of optical heads for disk-shaped media such as optical disks and magneto-optical disks.

2. Description of the Related Art Conventionally, optical disc devices have been equipped with at least one of a recording optical head and a reproducing optical head for the purpose of recording or reproducing a large amount of information at higher speeds. The one with multiple units was published in 1983.
It is known from the publication No.-224153.

Problems to be Solved by the Invention Currently, there are three types of media used in optical disc devices:

■Read only type (Read 0nly Media=RO
M) ■Write-once type (WORM,) ■Rewritable type (Rewritable) Among these, ■■
The recording/reproducing type generally records data by modulating the intensity of the irradiated laser light and causing physical or optical changes in the recording film formed on the optical disc, and requires a special recording medium. shall be. On the other hand, in the read-only type (■), information that is physically recorded in advance on an optical disk is reproduced by changing the reflected light from the optical disk (or diffraction), and the recording medium uses light as the recording medium. As long as the light is reflected, no special material is required; for example, a metal film such as aluminum may be used.

It is desired that such media take advantage of the feature of high mass production and be cheaper than ■■ type media.

On the other hand, when considered as a memory device, it is desired that the data transfer rate (the amount of data that can be recorded or reproduced per unit time) be high, and to achieve this, it is necessary to rotate the optical disk at high speed. However, when an optical disc is rotated at high speed, the frequencies of surface runout and track runout of the disc become high, and an actuator for making the optical disc follow a light spot is required to have high-speed response.

Further, since the acceleration of the deflection surface runout and the track runout increases in proportion to the square of the number of revolutions, the thrust force of the actuator is required in proportion to the acceleration.

For these reasons, there is a limit to the high speed rotation of optical discs.

Since the ■■-type optical disk has the added value of being able to record data, it can handle high-speed rotation by using a glass plate or the like with less surface runout as the disk substrate. However, because cost reduction is desired for ■-type optical disks, glass substrates, etc. cannot be used (if a glass substrate, etc. is used, the disk cost will not be much different from ■■-type optical disks, and If a substrate with large surface runout is used, the rotational speed of the disk must be reduced.

These problems cannot be solved simply by using a multiple head system as in the conventional example described in the above-mentioned publication, and it can be said that there is room for improvement in the multiple head system.

Means for Solving the Problems In an optical disc device in which a plurality of optical heads are disposed on a disc-shaped medium that is rotationally driven by a drive source, the invention as claimed in claim 1 provides an optical disc device in which a disc-shaped medium is used for recording and reproduction. A medium type discriminating means for discriminating whether the medium type is for reproduction only is provided, and a rotation speed switching means is provided for switching the rotation speed of the disk-shaped medium by the drive source to high or low in accordance with the discrimination output of the medium type discriminating means.

Further, in the invention as claimed in claim 2, a medium type determining means is provided for determining whether the disk-shaped medium is for recording/reproducing or only for reproducing, and the plurality of optical heads are selected according to the determination output of the medium type determining means. An optical head operation control means for controlling the operation is provided, and when the determined output of the medium type determination means is for recording/reproduction, the plurality of optical heads are made to access the same sector to detect the information recorded by the preceding optical head for recording. Immediately after, a verification operation is performed to reproduce the data using an optical head for reproduction, and when the determination output of the medium type determination means is for reproduction only, the plurality of optical heads are made to access another sector and independently perform a reproduction operation. I made it happen.

In the invention as set forth in claim 3, a plurality of spiral tracks are provided on a reproduction-only disk-shaped medium, and a medium type determining means is provided for determining whether the disk-shaped medium is for recording/reproduction or reproduction-only. Optical head operation control means is provided for controlling the operation of the plurality of optical heads according to the discrimination output of the medium type discrimination means, and when the discrimination output of the medium type discrimination means is for reproduction only, the plurality of optical heads are separated. The track can be accessed and playback can be performed independently.

According to the invention described in claim 1, when the disk-shaped medium used is for reproduction only, it can be rotated at a lower speed than when it is for recording and reproduction, so that surface runout and track runout are reduced. The acceleration is reduced, and a read-only optical disc can be used at a low price. In this case, any of the plurality of optical heads can be used for reproduction, and there is no substantial drop in the transfer rate even if the rotation speed is reduced.

On the other hand, in the case of an optical disc for recording and reproduction, it is possible to rotate at high speed by taking advantage of its material characteristics, so that a sufficient data transfer rate can be ensured.

Also, paying attention to the fact that it has a plurality of optical heads, claim 2
According to the described invention, in the case of a disk-shaped medium for recording and reproduction, one side of the optical head is used for recording and the other is used for reproduction, and by accessing the same sector, a verify operation immediately after recording is easily possible. Therefore, the data transfer rate during recording can be increased, and in the case of a playback-only disk-shaped medium, the transfer rate can be increased by using both of these optical heads for playback and accessing another sector for playback. This enables high-quality playback.

Furthermore, according to the third aspect of the invention, a plurality of spiral tracks are provided on a disk-shaped medium for reproduction only, and each optical head functioning for reproduction is made to access each track, so that tracing can be performed. There is no overlap, and a large amount of data can be played back continuously.

Example An embodiment of the present invention will be described based on the drawings.

First, an optical disk 2 as a disk-shaped medium is provided which is rotationally driven by a spindle motor 1 which is a driving source. A plurality of optical heads 3 and 4, in this case two optical heads, are arranged to face such an optical disc 2.

The optical head 3 is used for both recording and playback, and the optical head 4
is for playback only. These optical heads 3 and 4 are connected to separate seek motors 5 and 6, respectively, and are capable of seeking movement in the radial direction of the optical disk 2. These seek motors 5, 6 and optical heads 3, 4 are all connected to a drive controller (optical head operation control means) 7, and drive control, signal exchange control, etc. are performed.

Therefore, the optical disc 2 used in this embodiment may be either the read-only type described in (2) or the recording/reproduction type described in (■■), but it does not matter which type the optical disc 2 loaded in the device is. A medium type discriminating circuit (means) 8 for discriminating the type of media is mounted. As a medium type discrimination method, for example, as shown in FIG. 3, a sensor hole 10 is formed in a cartridge 9 containing an optical disk 2 according to the disk type, and the presence or absence of this sensor hole 10 is detected by a switch 11. It may be possible to use a device that distinguishes the type. Alternatively, a predetermined area on the optical disc 2 (
Information that can be used to determine the type of medium may be recorded in advance on the track (track), and the information in this area may be reproduced and determined after the optical disc 2 is inserted. In any case, medium discrimination may be performed using known techniques.

The medium type information discriminated by the medium type discrimination circuit 8 is taken into the drive controller 7, and is provided to control switching of the disk rotation speed by the spindle motor 1 through the rotation speed control circuit 12 serving as rotation speed switching means. . In addition, an operation mode is determined according to the type of medium and an instruction thereof is also made.

In such a configuration, first, when it is determined that the optical disc 2 is of the recording/reproducing type of ■ or ■, it is set to the recording/reproducing mode. In this mode, the drive controller 7 issues a command to the rotation control circuit 12 to rotate the spindle motor 1 at a high speed (compared to the ROM playback mode described later). Here, on the optical disc 2, there is a fourth track 13 for tracing the optical spot.
As shown in the figure, it is formed in a spiral shape (or concentric circle shape), and each track 13 is divided into units called sectors 14. Each sector 14 is divided into an ID section 14a in which necessary information such as a sector number is recorded in advance, and a data section 14b in which information is recorded. Therefore, the reproducing optical head 4 reproduces the sector number recorded in the ID section 14a, sends it to the drive controller 7, compares it with the target sector number to be recorded, and moves the seek motor 5, 6 is moved to seek, and both optical heads 3 and 4 are caused to seek onto the same track where the target sector exists.

In this state, the recording/reproducing optical head 3 first records data in the data portion of the target sector. Then, the recorded sector is immediately after recording (according to the example shown in FIG. 2, disk 1/
After three rotations), the optical head 4 passes under the light spot of the optical head 4 for reproduction only, so that reproduction can be performed immediately after recording. That is,
Verification of one track's worth of recorded data (confirmation of whether or not it has been recorded correctly) can be performed in one rotation. Therefore, the data transfer rate during recording is high.

It should be noted that when reproducing recorded data in this mode, the optical head 4 exclusively for reproduction is used, and the optical head 3 for recording and reproduction is also used or substituted as necessary.

On the other hand, if it is determined that the loaded optical disc 2 is of the playback-only type (2), the ROM playback mode is set. In this mode, the drive controller 7 issues a command to the rotation control circuit 12 to rotate the spindle motor 1 at a low speed (a speed at which the actuator can withstand disk surface runout and track runout acceleration). and,
Both optical heads 3 and 4 are used for reproduction, and unlike in the recording/reproduction mode, these optical heads 3 and 4 are made to access different sectors independently.

For example, as shown in FIG.
1 optical head 4 seeks sector m (seek control is the same), and thereafter optical head 3 seeks sector n, n+1 . n+
2. . . . , the optical head 4 has sectors m, m+l, m+2 . ~
are accessed in order to perform playback operations. The data read by these optical heads 3 and 4 is stored in the memories 15 and 16, respectively, and when these memories 15 and 16 become E゛ full with the desired amount of data, the data is stored in the host computer 17.
will be forwarded to.

According to the ROM playback mode of this embodiment, although the two optical heads 3 and 4 are driven at low speed, they are used independently to access different sectors, compared to the case of a single optical head. can play back twice as many sectors in the same amount of time. In other words, the time required to store the same sector of data in the memory is half that of the single optical head system, and the data transfer rate (playback speed) seen from the host computer 17 is 2 bytes. Therefore, even if the optical disc 2 is rotated at a low speed, it can be reproduced without reducing the data transfer rate.

In the case of a read-only optical disc 2, as shown in FIG. 7, there are two spiral tracks 13a.

13b may be formed in parallel, one optical head 3 may be assigned to one track 13a, and the other optical head 4 may be assigned to the other track 13b, and the reproduction operations may be performed in parallel. According to this, the tracks 13a and 13b traced by each of the optical heads 3 and 4 are arranged in five rows and do not overlap, making it easy to perform a large number of reproduction operations continuously.

By the way, these explanations are for optical discs that belong to any of ■■■.
The present invention can also be applied to a so-called partial ROM in which the remaining portion of the OM is a recordable and reproducible area. That is, according to the example described above, when it is determined that the ROM is a partial ROM, the drive controller 7 operates in the ROM playback mode described above when accessing the ROM area, and operates in the ROM playback mode described above when accessing the recording/playback area. The operation mode may be switched to operate in the recording/reproduction mode described above.

In any case, the method of this embodiment is particularly effective when a magneto-optical disk is used as the optical disk 2. first,
When reproducing information from a magneto-optical disk, a special optical system is required because the rotation of the polarization of the reflected light is detected rather than the intensity of the reflected light from the disk surface. For this reason, the optical head generally becomes large, and it is difficult to use two optical heads that are both capable of reproducing magneto-optical signals.

Therefore, the optical head 3 for recording and reproducing is a dual-purpose type that can write and record and can reproduce by changing the intensity of reflected light.
By making the reproducing optical head 4 capable of detecting magneto-optical signals based on changes in intensity of reflected light and polarization, the present invention can be carried out without increasing the size of the mechanism.

Effects of the Invention Since the present invention is configured as described above, according to the invention set forth in claim 1, when the disk-shaped medium used is for reproduction only, surface runout is reduced compared to when the disk-shaped medium is used for recording and reproduction. , it is possible to rotate at a low speed to the extent that the track runout acceleration is small, it is possible to use an inexpensive optical disc for playback only, and it is possible to use multiple optical heads for playback. Yes, there is no substantial drop in transfer rate even when the rotation speed is reduced, and in the case of optical discs for recording and playback, they can be rotated at high speeds by taking advantage of their material characteristics, so sufficient data transfer is possible. The rate etc. can be secured, and according to the invention described in claim 2,
In the case of a disk-shaped medium for recording and playback, one of the multiple optical heads is used for recording and the other for playback, and by accessing the same sector, a verify operation immediately after recording is easily possible, and the verification operation during recording can be easily performed. It is possible to increase the data transfer rate, and in the case of a playback-only disk-shaped medium, by using both of these optical heads for playback and accessing a different sector for playback, playback at a high transfer rate is possible. Furthermore, according to the third aspect of the invention, a plurality of spiral tracks are provided for a disk-shaped medium for reproduction only, and each optical head functioning for reproduction is accessed on each track, so that tracing is possible. There is no overlap between the two, making it possible to continuously reproduce a large amount of data.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, in which Fig. 1 is a schematic configuration diagram, Fig. 2 is a bottom view, Fig. 3 is a perspective view, Fig. 4 is a plan view showing tracks and sectors, and Fig. 5. FIG. 6 is a block diagram, and FIG. 7 is a plan view of a track showing a modified example. l... Drive source, 2... Disk-shaped medium, 3, 4...
- Optical head, 7... Optical head operation control means, 8.
...media type discrimination means, 12...rotation speed switching means,
13a, 13b...Spiral track diagram

Claims (1)

[Scope of Claims] 1. In an optical disc device in which a plurality of optical heads are arranged on a disc-shaped medium that is rotationally driven by a drive source, it is possible to determine whether the disc-shaped medium is for recording and reproduction or for reproduction only. An optical disc device characterized in that it is provided with a medium type discriminating means for discriminating, and a rotation speed switching means for switching the rotation speed of the disk-shaped medium by the drive source to high or low according to the discrimination output of the medium type discriminating means. 2. In an optical disc device in which a plurality of optical heads are arranged on a disc-shaped medium that is rotationally driven by a drive source, a medium type determining means for determining whether the disc-shaped medium is for recording and reproduction or for reproduction only. and an optical head operation control means for controlling the operation of the plurality of optical heads according to the discrimination output of the medium type discrimination means, and when the discrimination output of the medium type discrimination means is for recording and reproduction, the plurality of optical heads are controlled according to the discrimination output of the medium type discrimination means. When the optical head of the media is accessed to the same sector to perform a verification operation in which the information recorded by the preceding optical head for recording is reproduced by the optical head for reproduction immediately after, and the discrimination output of the medium type discrimination means is for reproduction only. An optical disc device characterized in that the plurality of optical heads are made to access different sectors and perform playback operations independently. 3. In an optical disk device in which a plurality of optical heads are disposed on a disk-shaped medium that is rotationally driven by a drive source, a plurality of spiral tracks are provided on a disk-shaped medium exclusively for reproduction, and the disk-shaped medium is a medium type determination means for determining whether the medium type is for recording/reproduction or reproduction only; an optical head operation control means for controlling the operation of the plurality of optical heads in accordance with a determination output of the medium type determination means; An optical disc device characterized in that, when the determined output of the medium type determining means is for reproduction only, the plurality of optical heads are made to access different tracks and perform reproduction operations independently.