JPH01303653A - Write-once optical disk/magneto-optical disk drive device - Google Patents

Abstract

PURPOSE:To miniaturize a device and to decrease a cost by using the magnetic force of a magnetic head conducted at the time of using a magnetooptical disk, fitting a magnetic body attracted by the magnetic force to a part of a wavelength plate and switching the condition of the wavelength plate automatically. CONSTITUTION:A part of a magnetic head 31 is extended to the outer circumferential side of an optical disk 1, an approximately L-shaped magnetic path body 32 is provided in a single body and the tip of a magnetic path body 32 is positioned to the position facing to a magnetic body 33 provided at the upper edge side of a 1/4 wavelength plate 11. When a magnetooptical disk is used as the optical disk 1, power is supplied to the magnetic head 31, a magnetic field is impressed to the magnetooptical disk, simultaneously, a magnetic force is generated even at the tip side of the magnetic path body 32, the magnetic body 33 fitted at the wavelength plate 11 is attracted, and the wavelength plate 11 is switched from an action condition to a non-action condition. Thus, a small and inexpensive DRAW type magnetooptical-cum-type device can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a write-once optical disk/magneto-optical disk drive device.

Conventional Technology Conventionally, optical disk devices capable of not only reproducing information but also writing and recording information include a write-once optical disk system that can be written only once, and a magneto-optical disk system that has an erasing function and is rewritable. .

Here, as write-once type optical disk devices, there are those shown in FIGS. 5 and 6. First, the write-once optical disc 1 is mounted and chucked on a turntable 2, and as the spindle motor 3 rotates, the optical disc 1 is rotationally driven via the boss portion 4, the rotating shaft 5, and the turntable 2. In the space between the optical disc 1 and the spindle motor 3, an optical pickup optical system 6 for recording/reproducing is provided.
will be placed.

First, the laser beam emitted from the semiconductor laser 7 is made into parallel light by the coupling lens 8, and after being beam-shaped by the beam shaping prism 9, it passes through the polarizing beam splitter 10 and passes through the quarter-wave plate 11. incident on . This one
After passing through the /4 wavelength plate 11, the beam is converted from linearly polarized light to circularly polarized light, and enters the deflection prism 12. The optical axis of the beam incident on the deflection prism 12 is deflected toward the optical disk 1 side, and the beam is focused and irradiated onto the surface of the optical disk 1 via the objective lens 13 as a minute spot. This minute spot is reflected by the optical disk 1, converted into parallel light by the objective lens 13, reflected toward the incident side by the deflection prism 12, and then enters the quarter-wave plate 11 again. The light that has passed through the quarter-wave plate 11 is converted from circularly polarized light to linearly polarized light, and then enters the polarizing beam splitter 10 again.

At this time, since the beam that entered the polarizing beam splitter 10 from the coupling lens 8 side re-enters as linearly polarized light with a phase shift of 90 degrees, the returned light does not pass through this polarizing beam splitter 10 and is reflected. Detection system 14
Head to. This signal detection system 14 detects a tracking error signal, a focus error signal, a reproduction signal, etc., and provides servo control for the actuator 15 of the objective lens 13 and the like.

Such an optical pickup optical system 6 is separated into a fixed optical system 16 and a moving optical system 17 in order to enable high-speed seek movement and the like. That is, only the objective lens 13 (including the actuator 15) and the deflection prism 12 are mounted in the moving optical system 17, and the remaining optical system members are mounted in the fixed optical system 16. Further, the moving optical system 17 is installed under the carriage structure so as to be able to seek freely on the rail 19 in the radial direction of the optical disc 1 by roller members 18 and the like, and is configured to be able to access any I/rack on the optical disc 1. ing.

In a write-once optical disk device having such a configuration, in order to configure it as a write-once/magneto-optical device that can selectively use a rewritable magneto-optical disk, it is necessary to generate a magnetic field for erasing records on the magneto-optical disk. In addition, the signal detection system 14 is equipped with a magneto-optical signal detection function (i.e.,
It is necessary to have a polarization direction detection function).

Furthermore, according to the method for detecting magneto-optical signals in magneto-optical disks, the minute spot formed on the surface of the magneto-optical disk must be linearly polarized light, whereas in the case of write-once optical disks, the spot is in a circularly polarized beam state. If it remains as it is, magneto-optical signals cannot be detected.

Therefore, when using a magneto-optical disk, it is necessary to switch to a minute spot in a linearly polarized state.

For this purpose, it is necessary to remove the quarter-wave plate 11 in the optical pickup optical system 6 when using a magneto-optical disk. However, if the quarter-wave plate 11 is simply removed, the incident side beam and the return side beam will become linearly polarized light with the same phase in the polarizing beam splitter 1O.
Both beams pass through the polarizing beam splitter 10, and the beams no longer enter the signal detection system 14.

For this reason, in the configuration shown in FIGS. 5 and 6, the polarizing beam splitter 10 is actually replaced with a beam splitter or a half mirror so that a certain amount of the incident beam is transmitted while the rest is reflected. Must be configured.

However, if a normal beam splitter or the like is used instead of the polarizing beam splitter 10, a problem will occur that will adversely affect the semiconductor laser 7. That is, if it is a polarizing beam splitter, all of the reflected light from the disk side will go to the signal detection system 14, but if it is a simple beam splitter, not all of the reflected light will go to the signal detection system 14, but at least a part of it will go to the signal detection system 14. The semiconductor laser 7 passes through a beam splitter etc.
It will be incident on .

It is known that such return light to the semiconductor laser 7 has an adverse effect on the power control of the semiconductor laser 7, and in particular, the lower the laser power, the greater the effect. In write-once and magneto-optical devices, it is generally necessary to record/reproduce write-once optical disks under lower laser power than magneto-optical disks, and when using magneto-optical disks, The effect of the return light on the semiconductor laser 7 is small and does not pose a particular problem, but when a write-once optical disk is used, the effect of the return light on the semiconductor laser 7 is so large that the recording/reproducing power control of the semiconductor laser 7 does not satisfy the specifications. will occur.

When configured as a write-once type and magneto-optical machine in this way,
Various problems may occur, but in order to avoid them,
At least the polarizing beam splitter 1 shown in FIG.
0 is a beam splitter (hereinafter referred to as a beam splitter 10 instead of a polarizing beam splitter). Then, use of the quarter wavelength plate 11 is selected. That is, when using a magneto-optical disk as a disk, by removing the 1/4 wavelength plate 11, the reflected light of the linearly polarized beam incident on the disk is allowed to enter the beam splitter 10 as linearly polarized light, and a certain amount of light is converted into a beam. The light is reflected by the splitter 1o and enters the signal detection system 14, and the remaining light is transmitted through the beam splitter 10.

In addition, when using a write-once optical disk 1, a 1/4 wavelength plate 1 is used.
1 remains set, and the linearly polarized light from the beam splitter 1o is made incident on the write-once optical disc 1 as circularly polarized light by the quarter-wave plate 11. Since the reflected light from the write-once optical disc 1 returns to the quarter-wave plate 11 as circularly polarized light,
When it passes through, it becomes linearly polarized light with a phase shift of 90' from the incident beam, and in this state returns to the beam splitter 10 and enters the beam splitter 10.

Therefore, all of the light is reflected by the beam splitter 10 and directed toward the signal detection system 14, and no light returns to the semiconductor laser 7 side.

That is, it is sufficient to provide a mechanism or means for removing the quarter-wave plate 11 when using a magneto-optical disk and inserting and setting it when using a write-once optical disk.

Such mechanisms and means include those shown in FIG. 7, FIG. 8, or FIG. 9.

First, in FIG. 7, a quarter-wave plate 11 is provided so as to be vertically movable with respect to the linear guide 2o via a sliding member 21. Then, it is moved up and down using the linear motor 22 as a driving source. This linear motor 22 is adjacent to one linear guide 20, and has a coil 2 integrated with the quarter wavelength plate 11 via a frame-shaped yoke 23, a magnet 24, and a sliding member 21.
It consists of 5. In such a configuration, by controlling the energization state to the coil 25, when a write-once optical disc is used, the quarter-wave plate 11 is connected between the beam splitter 10 and the deflection prism 12, as shown in FIG. 7(a). beam 2
Position it where 6 passes through. In other words, the 174-wavelength plate 11 is brought into operation with respect to the beam 26. On the other hand, when a magneto-optical disk is used, the coil 25 is energized to move the quarter-wave plate 11 to a position away from the position through which the beam B passes, as shown in FIG. 2(b). That is, the beam 26 is brought into a non-operative state in which the quarter-wave plate 11 does not function.

FIG. 8 is similar to that shown in FIG. 7, and the near motor 22 is formed into an arc shape, and the 1/4 wavelength plate 11 and the coil 25 are fixed to both ends of an arm 28 that is rotatable around a fulcrum 27. This allows the quarter-wave plate 11 to be inserted into and removed from the beam 26. FIG. 5A shows the state of the 1/4 wavelength plate 11 when a write-once optical disk is used, and FIG.

In FIG. 9, the quarter-wave plate 11 itself is always located at a position where the beam 26 passes (that is, it is not retracted to the outside as in FIGS. 7 and 8), but as shown in FIG. A near motor 22 is used to rotate the 1/4 wavelength plate 11 by 45 degrees. This utilizes the function of the quarter-wave plate 11, which transmits linearly polarized light as it is when rotated by 45 degrees in the in-plane direction, as shown in FIG. 9(b). It is. That is, FIG. 9(b)
In the state shown in , the quarter-wave plate 11 is located on the optical path of the beam 26, but it can be said to be in an inactive state in which it does not function as a quarter-wave plate. Here, in FIG. 9, the quarter wavelength plate 11 is fixed to the inner ring of the bearing 29, and the outer ring of the bearing 29 is fixed to the base of the fixed optical system 16. The coil 25 of the linear motor 22 and the quarter-wave plate 11 are connected by a connecting member 30, and the quarter-wave plate 11 is rotated by 45 degrees according to the linear motor 22. FIG. 5A shows the state of the quarter-wave plate 11 when a write-once optical disk is used, and FIG. 2B shows the state of the quarter-wave plate 11 when a magneto-optical disk is used.

Problems to be Solved by the Invention The quarter wavelength plate 1 shown in these FIGS. 7 to 9
The drive source for switching between the working state and the non-working state of 1 is based on the linear motor 22. Here, it is possible to use a solenoid instead of a linear motor, but in any case, there is a mechanism that automatically switches the state of the quarter-wave plate 11 when using a write-once optical disk and when using a magneto-optical disk. When installing, it is necessary to add a drive source as well.
This increases the size of the device and increases costs.

Means for Solving the Problem A drive source that switches the wavelength plate between an active state and a non-active state in the optical path of an optical pickup in accordance with the selective use of a write-once optical disc and a magneto-optical disc is energized when the magneto-optical disc is used. The magnetic force is generated by a magnetic head for recording and erasing, and a magnetic material that is attracted by this magnetic force is attached to a part of the wave plate.

When using a working magneto-optical disk, recording and erasing requires laser beam irradiation and application of a magnetic field, and a magnetic head is required to apply a magnetic field to the magneto-optical disk. On the other hand, application of a magnetic field by such a magnetic head is unnecessary when using a write-once optical disk. Further, the wavelength plate also needs to be activated when the write-once optical disk is used, but it needs to be made inactive when the other magneto-optical disk is used. Therefore, by switching the magnetic head between a energized state and a non-energized state when using a magneto-optical disk and a write-once optical disk, the magnetic force can be used as a driving source to switch the state of the wave plate, and the magneto-optical When the disk is in use, the magnetic material attached to the wave plate is attracted by the magnetic force, and the wave plate is switched from a steady state of operation to a non-operation state. That is, a separate dedicated drive source is not required for switching the wave plates.

Embodiment An embodiment of the tree opening will be explained based on FIGS. 1 and 2. The same parts as those shown in FIGS. 5 to 7 are indicated using the same reference numerals. The overall structure and operation are similar to those shown in FIGS. 5 and 6, but as mentioned above, the magnetic head 31 generates a magnetic field for recording and reproducing so that it can also be used as a magneto-optical disk. is optical disc 1
is fixedly placed at the top of the This magnetic head 31 has a length extending at least in the radial direction of the optical disk 1 (a length that covers the recording area), and when a magneto-optical disk is used as the optical disk 1, it can be used for recording, reproducing, and erasing. Although it is energized and generates a magnetic field even in the operation mode, when a write-once optical disk is used, it is not energized and merely exists.

In this embodiment, as shown in FIG. 7, the magnetic head 3 is used instead of the linear motor 22 as the drive source for the quarter-wave plate 11 which is switched between the working state and the non-working state.
This uses a magnetic force of 1. For this reason, first, a part of the magnetic head 31 is integrally provided with an abbreviated magnetic path body 32 extending toward the outer circumferential side of the optical disk 1 and bent toward the vicinity of the quarter-wave plate 11. ing. The tip of this magnetic path body 32 is located at a position opposite to a magnetic body 33 fixedly provided on the upper end side of the quarter wavelength plate 11.

In such a configuration, when a write-once optical disk is used as the optical disk 1, the magnetic head 3 is not energized. Therefore, no magnetic force is generated from the magnetic path body 32 to the magnetic body 33, and the quarter wavelength plate 11 is as shown in FIG. 2(a).
As shown in FIG. 2, its own weight causes it to move in the optical path, that is, across the beam 26.

When a magneto-optical disk is used as the optical disk 1, the magnetic head 31 is energized and a magnetic field is applied to the magneto-optical disk. At the same time, a magnetic force is generated on the tip side of the magnetic path body 32, and the 1/4 wavelength plate 11, which can be slid upward by the linear guide 20 and the sliding member 21,
2. Due to the attractive magnetic force acting between the magnetic bodies 33, as shown in Fig. 2 (b)
) is displaced as shown. That is, the quarter-wave plate 11 is switched to a non-active state out of the path of the beam 26.

In this way, according to the present embodiment, the magnetic force generated by the magnetic head 31, which is inevitably mounted as a write-once type/magneto-optical type, is used as the driving source for switching the state of the quarter-wave plate 11. Unlike the linear motor 22, a separate dedicated drive source is not required. In other words, it is sufficient to add the magnetic material 33, etc., and it is possible to avoid increasing the size of the optical pickup.

□In this embodiment, when using a magneto-optical head, the magnetic head 31 is energized not only during recording and erasing but also during reproduction, but since the irradiation laser power during reproduction is low, the magnetic head 31 Even if a magnetic field is applied, it does not affect the magneto-optical disk (erasure of information, etc.).

FIG. 3 shows a modification corresponding to FIG. 8, in which the linear motor 22 in FIG. 8 is omitted and a magnetic body 33 is attached to the other end of the arm 28 connected to the quarter-wave plate 11. be. As a result, when using a write-once optical disk, there is no magnetic force from the magnetic head 31 (magnetic path body 32), and the magnetic body 33
is not attracted, and the 1/4 wavelength plate 11 is
), it assumes an operating state located in the path of the beam 26 (for this purpose, the magnetic body 33 side may be made heavier, for example). On the other hand, when a magneto-optical disk is used, the magnetic head 31 is energized, and the magnetic body 33 passes through the magnetic path body 32.
is attracted by magnetic force. As a result, 1/4 wavelength plate 1
1 is rotated to a position outside the optical path, away from the beam 26, as shown in FIG. 3(b), and is switched to a non-operating state.

FIG. 4 shows a modification corresponding to FIG. 9, in which the linear motor 22 in FIG. 9 is omitted as in the case of FIG.
A magnetic body 3 is attached to the other end of the arm 30 connected to the 4-wavelength plate II.
3 is attached.

As a result, when using a write-once optical disk, there is no magnetic force from the magnetic head 31 (magnetic path body 32), and the magnetic body 33 is not attracted.
is located in the path of the beam 26 as shown in FIG.
) The operating state is the same as in the case of ) (also in this case, for example, the magnetic body 33 side may be made heavier). On the other hand, when a magneto-optical disk is used, the magnetic head 31 is energized, and the magnetic body 33 is attracted by magnetic force through the magnetic path body 32. As a result, the 1 which is rotatably supported by the bearing 29
As shown in FIG. 4(b), the /4 wavelength plate 11 is rotated in the plane by 45° about itself, and although it is located in the optical path of the beam 26, it has no effect of passing linearly polarized light as it is. state.

By the way, in this embodiment, the quarter wavelength plate 11 placed between the beam splitter 10 and the deflection prism 12 is applied to switch the state depending on the type of the optical disc 1.
In addition, for example, in the case of an optical pickup configuration in which the incident laser beam is reflected by a beam splitter and guided to the optical disk side, and the reflected light from the optical disk is guided to a detection optical system arranged on the return transmission side of the beam splitter, It can be similarly applied to the case where a half-wave plate is provided at the front stage (semiconductor laser side) on the incident side of the beam splitter so that it can be switched between an active state and a non-active state, and is configured as a write-once type and a magneto-optical type. . In other words, in a half-wave plate, if the incident polarization plane coincides with the crystal axis, S-polarized light is transmitted as S-polarized light, but if the crystal axis is rotated by 45 degrees in the plane with respect to the polarization plane, S-polarized light will be converted to p-polarized light. Therefore, by putting the 172-wavelength plate in an active state when a write-once type optical disk is used, and switching it to a non-active state when using a magneto-optical disk, it is possible to make it a write-once type and a magneto-optical type. As a drive source for switching the state of such a half-wave plate, the magnetic force of the magnetic head can be used, as in the case of the quarter-wave plate 11. In the case of this 1/2 wavelength plate, the working state and non-working state are 1/2 with the crystal axis tilted by 45 degrees.
Even if a wave plate is prepared and is placed in the optical path in the active state as in Figures 2 and 3, and in the non-active state as in the case of Figure 4, it is always in the optical path as in the case of Figure 4. It is also possible to use a combination in which the polarization direction is changed by 90 degrees due to the in-plane rotation of 45 degrees, and the active state and the non-active state are obtained.

Effects of the Invention The present invention focuses on a magnetic head for recording and erasing on a magneto-optical disk, which is required when configured as a write-once type/magneto-optical type as described above, and selectively adjusts the magnetic head according to the type of optical disk. By associating a wavelength plate with this magnetic head that is selective depending on the type of optical disk, the magnetic force can be used as a driving source for switching the wavelength plate by energizing the magnetic head when using a magneto-optical disk. ,
Therefore, by simply providing a magnetic material that is attracted by the magnetic force of the magnetic head on the wavelength plate side, it is possible to configure a write-once type and magneto-optical type without the need for a separate dedicated drive source, making it compact and inexpensive. can.

[Brief explanation of the drawing]

FIG. 1 is a side view showing one embodiment of the present invention, FIG. 2 is a front view showing the vicinity of the quarter wavelength plate in an operating state and a non-working state, and FIG. 3 is a working state and a modified example. 4 is a front view of the working state and the non-working state showing different modifications, FIG. 5 is a plan view showing the conventional example, FIG. 6 is a side view thereof, and FIG. 7 is a front view of the non-working state. 9 is a front view of the working state and non-working state showing the vicinity of a quarter wavelength plate using a conventional drive method, FIG. 8 is a front view of the working state and non-working state showing a different conventional example, and FIG. FIG. 3 is a front view of a different conventional example in an active state and a non-active state. 1...Optical disc, 11...Wave plate, 31...Magnetic helad, 33...Magnetic material storage punishment 1 Kazuma' Bacteria Island Z diagram (a) (b) &/1. ．． lZb Figure 33 (a) (),,) Figure 114 (a) (I)), Figure J35

Claims (1)

[Claims] Depending on the selective use of a write-once optical disk or a magneto-optical disk, a wavelength plate is provided in a part of the optical path of the optical pickup so that it can be switched between an active state and a non-active state, and a magnet for recording and erasing information on the magneto-optical disk is provided. In a write-once optical disk-magneto-optical disk drive device provided with a head, a drive source that switches the wavelength plate between an active state and a non-active state according to selective use of the disk is energized when the magneto-optical disk is used. A write-once optical disk characterized in that the magnetic force is generated by the magnetic head, and a magnetic body that is attracted by the magnetic force is attached to a part of the wavelength plate.
Magneto-optical disk drive device.