JPS637527A - Optical recording and reproducing device having plural optical spots - Google Patents

Abstract

PURPOSE:To always attain the trace of the same guide track, by providing a means to detect the moving position of a movable body of a driving means which moves plural optical spots independently in a direction almost vertical to the guide track. CONSTITUTION:The light of a light emitting element 1 is projected on the turning mirror 22 of the driving means which performs the tracking of an optical spot M, and reflected light beams are received by an optical detector 2. At the time of turning the turning mirror 22, the light beams from the light emitting element 1 are displaced on the optical detector 2 corresponding to a turning angle, and the optical detector 2 is the two-division one, and in which dividing direction is set at displacement direction, and by taking a difference between divided photoreceiving quantities, the quantity of displacement can be detected efficiently. Also relation between the turning mirror 22, and the relative aberration of two optical spots L and M, is set at constant relation, and the output of the optical detector 2 operates the turning mirror 22 only when the relative aberration of those two optical spots is less than 1/2 of the pitch of a guide track 3, thereby, the tracking control of the optical spot M can be performed. In this way, it is possible to always trace the same guide track by the plural optical spots.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention uses a lens or the like to irradiate two tiny optical apertures 7) onto an optical recording medium (for example, an optical disk) with a K aperture, and - An erasable optical recording and reproducing device that records and reproduces a signal with one optical spot and erases the signal with the other optical spot, and can record and reproduce the signal repeatedly, or an erasable optical recording and reproducing device that records a signal with one optical spot and erases the signal with the other optical spot, The present invention relates to an optical recording/reproducing apparatus having a plurality of optical spots, such as an optical recording/reproducing apparatus capable of reproducing a recorded signal instantly.

2. Description of the Related Art As an optical recording/reproducing device having a plurality of optical spots, the one shown in Japanese Patent Application No. 125906/1982 was previously proposed. This is an example of an erasable optical recording/reproducing device that uses the thermal energy of a laser beam to reversibly change the optical density of the recording thin film of an optical disk. Dislocations between states or dislocations between one amorphous state are repeatedly used.

The device as described above has a plurality (two) of light spots. An example of its configuration is shown in FIG.

Figure 2 shows - of a disk-shaped optical recording medium (hereinafter referred to as an optical disk).
3 is a guide track provided on the optical disk. On the guide track 3, there is a circular first optical groove 7) L and an oblong second optical groove long in the track direction. The configuration is such that a circular first optical spot L is used to record and reproduce a signal, and an oval second optical spot 7) M is used to erase the signal.

In the device using two light spots as described above, since the width of the guide track 3 is generally very small, about 0.5 μm, the first light spot L and the second light spot are separated in the direction perpendicular to the track. It is necessary to maintain the relative position with spot M with high precision and stability. For this reason, the above-mentioned apparatus has a structure that prevents the relative positional deviation of the two light spots, and the structure is shown in FIG. 3.

In FIG. 3, the part surrounded by a dashed line indicates an optical head, .gamma. is a semiconductor laser that generates light of wavelength .lamda.1, and 2 indicates its output light beam. A condenser lens 8 condenses the output light of the semiconductor having a spread into a substantially parallel light beam.

9 is a filter that transmits light with wavelength λ1 and reflects light with wavelength λ2, which will be described later; 10 is a polarizing beam splitter effective for light with wavelengths λ1 and λ2; 11 is a wave plate for wavelength λ1; and 12 is an aperture lens. be.

The light beam 2 from the semiconductor laser 7 passes through these optical elements and enters the aperture lens 12 . The aperture lens 12 narrows down the incident light beam 2 to form a substantially circular light spot L on the guide track 3.

13 is a semiconductor laser that generates a light beam m having a wavelength λ2, and 14 is a condenser lens. 22 is a reflective mirror,
It has a rotatable configuration. Reference numeral 15 is a wave plate for wavelength λ2, and filter 16 has a function of transmitting light of wavelength λ1 and reflecting light of wavelength λ2. The light beam m emitted from the semiconductor laser 13 is reflected by a reflecting mirror 22 .
It is reflected by the polarizing beam splitter 10 and sent back to the wave plate 1.
5, and then passes through the polarizing beam splitter 10,
The light passes through a pure wave plate 11 and enters an aperture lens 12 . Aperture/
A light spot M is formed on the lens 12 on substantially the same guide track 3 as the light spot L, and is oval in shape and whose major axis direction coincides with the direction of the guide track.

In this way, the light spots L and M+i are placed on the second guide track.
The arrangement as shown in the figure can be realized by making the incident angles of the light beam l1m incident on the aperture lens 12 different from each other.

The light beam 2 reflected from the optical disk is passed through the aperture lens 1.
2 + V4 wave plate 11. Polarized beam sgritter 101
% wave plate 15. The light passes through a filter 16 and is guided to a photodetector 18 via a lens 17 for obtaining control signals for focus and tracking.

The photodetector 18 is composed of a PIN diode divided into four parts,
Regenerate signals from these outputs using a known method.

A control signal for focusing and tracking of the first light spot (L) is obtained.

On the other hand, the reflected light from the optical disk of the light beam m is transmitted through the aperture lens 12. It passes through the V4 wavelength plate 11. Here, for example, by using a semiconductor laser with a wavelength λ1 of 780 nm and a wavelength λ2 of 830 nm, most of the light transmitted through the pure wave plate 11 is reflected to the semiconductor laser 7 side at the polarization beam beam IJ, and is further filtered. 9 and guided to a two-divided photodetector 19.

A tracking control signal for the second light spot (M) is obtained from the differential output of this two-split photodetector 19.

The aperture lens 12 is held by an aperture lens driving element 2Q so as to be movable in two axes: an optical axis direction for focusing and a direction perpendicular to the track for tracking.

Therefore, the first light spot L and the second light spot M are moved simultaneously and by the same amount in the direction perpendicular to the track by the aperture lens drive element 20. This diaphragm lens and driving element 20 may have a known voice coil type structure, and can perform focus control corresponding to the surface runout of the optical disk of the first optical disk (L) and tracking control against track eccentricity using known techniques.

At this time, the second light spot M also moves in the same manner as described above. However, since a rotatable reflection mirror 22 is provided in the optical path of the second optical subsystem (M), the rotation of the reflection mirror 22 can cause damage to the light. ll Second light spot.

The light spot M can be moved independently of the first light spot L in the direction perpendicular to the track. This is because the angle of incidence of the light beam m incident on the aperture lens 12 in the direction perpendicular to the track changes.

As described above, the tracking control signal for the second light spot M is obtained from the two-split photodetector 19, but the tracking control signal for the second light spot M is obtained by rotating the reflecting mirror 22 using a known technique. Tracking control is possible.

Although the drive means for moving the second optical switch M has been described as the rotatable reflection mirror 22, drive means for moving the semiconductor laser 13 by a piezoelectric element have also been proposed.

As described above, the first driving means moves the two light spots together in a direction substantially perpendicular to the track, and the second driving means moves the second light spot independently of the first light spot. In an optical recording/reproducing device having a plurality of optical spots, even if the relative positions of the two optical spots occur for some reason in the vertical direction, the first and second By applying tracking control using the driving means, it becomes possible to accurately track the guide track, and it is possible to prevent relative positional deviation between the two light spots.

Problems to be Solved by the Invention However, with the above configuration, it is difficult to ensure that the two light spots always follow the same guide track, that is, when controlling the tracking of the two light spots respectively. , there is a possibility that separate guide trunks may be tracked, and in order to prevent this, the configuration of the device becomes complicated and expensive.

This is because if the relative positional deviation between the two optical spots is greater than or equal to the guide track pitch A, the tracking control signals obtained from each optical spot will be generated by different guide tracks. This is because tracking control is applied. In other words, in order for the two light spots to always track the same guide track, the relative positional deviation of the two light spots must be below the pitch of the guide track.

However, the conventional second driving means for moving the second light spot (means for moving the rotatable reflection mirror 22, or semiconductor laser 13) is a movable body and is susceptible to external disturbances (for example, external vibrations). , or drive source noise during driving by electromagnetic force, etc.), there is a possibility that the relative positional deviation between the two light spots will exceed the pitch A of the guide track. Therefore, as described above, tracking control may be applied to separate guide tracks.

Further, the second driving means is required to be movable even during normal use without the above-mentioned disturbances, and to maintain the neutral position with extremely high precision.

In view of this, an object of the present invention is to provide an optical recording/reproducing device having a plurality of light spots, which has a simple configuration and allows two light spots to always track the same guide track.

Means for Solving the Problems The present invention is an optical recording/reproducing apparatus having a movable position detecting means for a movable body of a driving means for independently moving a plurality of light spots in a direction substantially perpendicular to a guide track.

Function: With the above-described configuration, the present invention can detect the amount of relative positional deviation between two light spots when the above-mentioned disturbance occurs. This is because the movable position of the movable body of the drive means for independently moving the light spots and the relative positions of the two light spots are in a fixed relationship, and this relationship makes the above possible.

Therefore, the movable position detection means of the movable body confirms that there is a relative positional deviation between the two light spots or that it is below the bar plate of the pitch of the guide track, and then operates the drive means to independently move the light spots. Tracking control guarantees that the same guide track is always followed.

Embodiment FIG. 1 shows an optical recording/reproducing apparatus having a plurality of optical spots in a first embodiment of the present invention. In FIG. 1, the part surrounded by a dashed line indicates an optical head, and parts that are the same as those in the conventional device are given the same numbers. 1 is a light emitting element such as a phototransistor, and 2 is a two-part photodetector that receives light from the light emitting element.

In this embodiment, the optical spots L and M shown in FIG. 2 are formed in the same manner as described in the conventional apparatus, and tracking control signals from the respective optical spots can be detected. The difference from the conventional device is that the light from the light emitting element 1 is irradiated onto a rotary mirror 22 of the driving means for tracing the optical spora) M, and the reflected light is received by the photodetector 2. When the rotating mirror 22 rotates, the light from the light emitting element 1 is displaced on the photodetector 2 according to the rotation angle. The photodetector 2 is divided into two sections, with the direction of division being the direction of displacement of light, and the amount of displacement can be detected with high accuracy by taking the difference between the amounts of received light. That is, the combination of the light emitting element 1 and the photodetector 2 serves as means for detecting the rotational position of the rotational mirror 22.

Here, the rotating position of the rotating mirror 22 and the two optical spoilers)L
Since the relative positional deviations of M and M are in a constant relationship, the output of the photodetector 2 when the relative positional deviation is due to the pitch of the guide track 3 can be found.

Therefore, the output of the photodetector 2 operates the rotary mirror 22 only when the relative positional deviation of the two light spots is below the pinch bar of the guide track 3, and performs tracking control of the optical spora) M. Set it as a configuration.

By doing so, the device will not operate when the above-mentioned disturbance is applied to the device, and the above-mentioned action will ensure that the light spots L and M always follow the same guide track, making the device simple. It becomes the composition.

As a second embodiment of the present invention, although not particularly shown, the output of the photodetector 2 is used to adjust the relative positional deviation of the two light spots to a range below the bar plate of the pitch of the guide track 3. The moving mirror 22 is driven. And Hikari Subo y
Tracking control of M is applied.

This eliminates the need for the rotating mirror 22 to maintain the neutral position with extremely high accuracy.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, in an optical recording/reproducing device having a plurality of light spots, it is possible to have the plurality of light spots always track the same guide track with a simple configuration, and its practical effects are achieved. is big.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a perspective view showing the arrangement of an optical disk and a light spot, and FIG. 3 is a block diagram showing the previously proposed device. 1...Light emitting element, 2...Photodetector, 3
...Guide track, 7, 13... Semiconductor laser, 8, 14... Condensing lens, 12...
...Aperture 7, 18.19...Photodetector, 22...Rotating mirror. Name of agent: Patent attorney Toshio Nakao and 1 other person7-
--Emitting element chiz-S Tomoe 6 3- Kanai trough 7, no 3- Ushikotaishi-Size, 14 ~ Light condensing lens 1.16 --- Filter 10 --- Polarization几peamsub1J-/ri/7,15--'y4 7 skin tool Saino (12-
Consensus Zone 11---Lens Zθ-Lens Hondo Boushi 1st Ward
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Claims (3)

[Claims] (1) Using a plurality of semiconductor lasers and the light beams emitted from the plurality of semiconductor lasers using the same aperture lens,
an optical means for forming a plurality of light spots on a straight line substantially parallel to an information track of an optical recording medium; a first driving means for moving the plurality of light spots together in a direction substantially perpendicular to the information track; An optical system having a plurality of light spots, comprising a second driving means constituted by a movable body that moves the plurality of light spots independently in a direction substantially perpendicular to the information track, and a movable position detection means of the movable body. Recording and reproducing device. (2) The second drive means is operated when the position detection signal from the movable position detection means of the movable body is within a range of 1/2 or less of the pitch of the information track. An optical recording/reproducing device with multiple optical spots. (3) Claims characterized in that the second drive means is driven so that the position detection signal from the movable position detection means of the movable body is within a range of 1/2 or less of the pitch of the information track. 2. An optical recording/reproducing device having a plurality of optical spots according to claim 1.