JPS62170039A - Optical recording and reproducing device having plural light spots - Google Patents

Abstract

PURPOSE:To always allow plural light spots to trace the same guide track with a simple constitution by providing a member limiting the movable range to a movable body moving the light spots in a direction perpendicular to that of the guide track. CONSTITUTION:A rotatable reflection mirror 22 is provided in an optical path of the 2nd light spot M by a light beam (m) from a semiconductor laser 13 and the light spot M is moved in a direction perpendicular to the direction of the guide track 3 independently by the turning of the mirror 22. Then the members 1, 2 limiting the movable range of the mirror 22 are provided to the mirror 22 and the limiting range is set to 1/2 or below of a pitch of the guide track 3. Thus, even if an external disturbance is exerted to the titled device, since the movement of the light spot is limited to 1/2 or below of the track pitch, the plural light spots always trace the same guide track.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention focuses two laser beams onto an optical recording medium (for example, an optical disk) using a lens or the like to form two minute optical spots, and one of the optical spots.・An erasable optical recording and reproducing device that records and reproduces a signal with one optical point, erases the signal with the other optical point, and can repeatedly record and reproduce the entire signal, or records a signal with one optical point, The present invention relates to an optical recording/reproducing apparatus having a plurality of optical channels, such as an optical recording/reproducing apparatus capable of immediately reproducing a recorded signal by reproducing using the other optical spot.

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 on the original disk. Dislocations between a crystalline state and a crystalline state, or dislocations between one amorphous state and another stable amorphous state are repeatedly utilized.

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

FIG. 2 is an enlarged view of a part of a disk-shaped optical recording medium (hereinafter referred to as an optical disk), and 3 is a guide track provided on the original disk. A circular first optical spora) L and a second oval original spot M elongated in the track direction are irradiated, and a signal is recorded and reproduced using the circular first optical spora) L, and an oval second optical spora is used. ) M erases the signal.

In the device that uses the two optical sporaters as described above, the width of the guide track 3 is generally very small, about 0.5 μm, so the first light in the direction perpendicular to the track 3 is very small. It is necessary to maintain the relative position of the spora) L and the second light spot V with high accuracy and stability. For this reason, the above-mentioned device 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, and 7 is a semiconductor laser which generates light of wavelength λ1, and its output light beam is indicated by 'frl'. Reference numeral 8 is a condenser lens that condenses the expanded output light of the semiconductor laser 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 filter with wavelength λ1. Polarizing beam splitter effective for light of λ2, 11 is A for wavelength λ1
In the wave plate, 12 is an aperture lens.

The light beam l of the semiconductor laser 7 passes through these optical elements and enters the aperture lens 12. The aperture lens 12 apertures the incident light beam lt to form a substantially circular original spot L on the guide track 3.

13 is a semiconductor laser that generates a light beam mi of wavelength λ2, and 14 is a condenser lens. 22 is a reflective mirror 1
It has a rotatable configuration. Reference numeral 16 denotes a dead wave plate for the wavelength λ2, and the filter 16 has a function of transmitting the light of the wavelength λ1 and reflecting the light of the wavelength λ2. The light beam m emitted from the semiconductor laser 13 is reflected by a reflecting mirror 22 .
After being reflected by the polarizing beam splitter 10 and passing through the entire A wavelength plate 16, it is reflected by the filter 16 and passed through the A wavelength plate 16 again.
, then passes through the polarizing beam splitter 1o, and V
The light passes through a four-wavelength plate 11 and enters an aperture lens 12 . A diaphragm lens 12 forms an oval light spot M' on the guide track 3 that is substantially the same as the light spot L, and whose major axis direction coincides with the direction of the guide track.

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

The light reflected from the original disk of the original beam l is reflected by the aperture lens 1
2.1/4 wavelength plate 11. Polarizing beam splitter 10. V
4 wavelength plate 16. The light passes through a filter 16 and is guided to a photodetector 18 via a lens 17 for obtaining control signals for focusing, tracking, and I-king.

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 single beam m is.

The diaphragm 9 lens and the 'A wavelength plate 11 are completely transmitted. Here, for example, by using a semiconductor laser with a wavelength λ1 of 780 tz and a wavelength λ2 of 830 m, most of the light transmitted through the A wavelength plate 11 is transmitted to the semiconductor laser 7 at the polarizing beam splitter 1Q.
The light is reflected to the side, further reflected by the filter 9, and guided to the two-split photodetector 19. From the differential output of this two-split photodetector 19, a tracking control signal for the second optical sensor (y)M is obtained.

The y-diaphragm lens 12 is held movably in two axes by an diaphragm lens drive element 2o: in the optical axis direction for focusing and in the direction perpendicular to the track for tracking.

Therefore, the first optical spora (L) and the second optical spora ()M are simultaneously moved by the aperture lens driving element 20 in the vertical direction and by the same amount. This diaphragm lens drive 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 light spot (L) and tracking control against track eccentricity using known techniques.

At this time, the second original spot M also moves in the same way as described above. However, since a rotatable reflection mirror 22 is provided in the optical path of the second light spora (5) M, the rotation of the first reflection mirror 22 causes the second original spot M to be reflected by the first light spora). L
It becomes possible to move independently of the track in the direction perpendicular to the track.

This is the traverse of the original beam m incident on the aperture lens 12.
This is because the angle of incidence in the vertical direction changes as the angle increases.

As described above, the tracking control signal for the second optical spoiler (M) is obtained from the two-split photodetector 19, but the second optical spoiler (M) can be detected by rotationally driving the reflecting mirror 22 using a known technique. M tracking control is possible.

Although the driving means for moving the second light spot M' has been described as the rotatable reflection mirror 22, driving means for moving the semiconductor laser 13 using a piezoelectric element has also been proposed.

As described above, the first driving means moves the two light spots together in a direction substantially perpendicular to the track.

In an optical recording/reproducing device having a plurality of light spots, which is configured to have a second driving means that moves the second light spot independently of the first light spot, two light spots may be moved for some reason. Even if there is a relative positional deviation in the vertical direction in the tracks of the light spots, it is possible to accurately track the guide track by applying tracking control using the first and second driving means, so that the two light spots can be The problem to be solved by the present invention is to be able to prevent relative positional deviations. However, with the above configuration, it is difficult to ensure that the two light spots always follow the same guide track. When controlling the tracking of two light spots, there is a possibility that each guide track must be tracked separately, and to prevent this, the configuration of the device becomes complicated and expensive. Ta.

This is because if the relative positional deviation of the two light spots (y) is greater than the guide track pitch A, the tracking control signals obtained from each light spot will be caused by different guide tracks, and This is because tracking control is applied to the track. 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 less than or equal to 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 the semiconductor laser 13) is.

Due to disturbances in the movable body (for example, external vibrations or drive source noise during driving due to electromagnetic force, etc.), the relative positional deviation of the two light spots may cause the beam on the guide track to
There is a possibility that the child's grade will be higher than A. Therefore, as described above, tracking control may be applied to separate guide tracks.

In view of this, an object of the present invention is to provide an optical recording/reproducing device having a plurality of light spots that can always track the same guide track with a simple configuration.

SUMMARY OF THE INVENTION The present invention provides for multiple optical spoilers 11 to be moved independently and substantially perpendicularly to a guide track. This is an optical recording/reproducing device having a plurality of optical ports in which the movable body of the driving means is provided with four members that completely limit the movable range.

Operation The present invention has the above-described configuration, and is a member that limits the movable range of the movable body of the drive means that independently moves the five light spots even when the above-mentioned disturbance occurs, and the relative positional deviation of the light spots is guided. This makes it possible to keep track of the same number of guides at all times, ensuring that the same number of guides is always tracked.

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 represents the optical head, and parts that are the same as those of the conventional device are given the same numbers. 1 and 2 are members that limit the movable range of the rotating mirror 22.

In this embodiment, the optical spoilers 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 members 1 and 2 are provided on the rotating mirror 22 of the driver/stage that performs the optical spora) M's tiger/tsukifugu. The members 1 and 2 are set so that the movement range of the light spot M due to the rotation of the rotating mirror 22 is equal to or less than the pitch of the guide track 3.

Because of these members 1 and 2, if a disturbance is applied to the device,
The above-mentioned action ensures that the optical spora) L and M always follow the same guide track.

The device has a simple configuration.

FIG. 4 shows a second embodiment of the invention. In FIG. 4, reference numeral 23 denotes a member that integrates members 1 and 2 that limit the movable range of the rotary mirror 22, and is rotatable about a shaft 24 so that the movable range can be adjusted. (Note that the other configurations of the second embodiment are the same as those of the tenth embodiment.) This means that the condition that the original spots L and M do not track separate guide tracks is the relative positional deviation of the original spots. This is because the limit of the movable range is not symmetrical with respect to the neutral position of the rotating mirror 22, which is less than % of the pinch of the guide track. That is, in the initial state, the rotating ξ-lar 22 is in a neutral position, and the optical spoilers L and M are formed on the guide track 3, but if there is some relative positional deviation of the optical spot, the guide track is The pitch % condition is not symmetrical with respect to the neutral position of the rotating mirror 22. In the initial state, it is very difficult to completely eliminate the relative positional deviation of the light spot, and it is practical to allow the relative positional deviation within a certain range. Therefore, when restricting the moving range of the light spot, the rotating mirror 2
Since the movable range of 2 is not symmetrical with respect to the neutral position, it is necessary to correct the relative positional deviation of the light spot.

In the second embodiment, the member 23 is adjustable and the above-mentioned correction can be easily performed.

In addition, in the first and second embodiments, the driving means for independently driving the plurality of optical spots was a rotating mirror.
The driving means may have any configuration as long as it is a movable body, and the member that limits the movable range does not need to have the configuration as in the embodiment.

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 drawings]

FIG. 1 is a plan view showing one embodiment of the present invention, FIG. 2 is a perspective view showing the arrangement of an optical disc and an optical spot, and FIG.
This figure is a plan view showing the previously proposed device, and FIG. 4 is a plan view showing a part of another embodiment of the present invention. 1.2.23... Member that limits the movable range of the rotating mirror, 3... Guide track, 7, 13...
... Semiconductor laser, 8.14 ... Curved condensing lens, 1
2...Curved aperture lens, 18.19...Photodetector, 22...Rotating mirror. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure/, z, Jβ/)j: 1 or λλ Figure 3 Figure 4

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 straight lines substantially parallel to an information track of an optical recording medium; a driving means for moving the plurality of light spots together in a direction substantially perpendicular to the information track; and a drive means for moving the plurality of light spots together in a direction substantially perpendicular to the information track; A plurality of light spots characterized by comprising a driving means constituted by a movable body that moves each spot independently in a direction substantially perpendicular to the information track, and a member that limits the movable range of the movable body. Optical recording and reproducing device. (2) The range in which the plurality of light spots are independently moved is set to 1/2 or less of the pitch of the information track by means of a member that limits the movable range of the movable body. Optical recording and reproducing device with multiple optical spots. (3) A plurality of light spots according to claim 1, characterized in that the member that limits the movable range of the movable body is movable, and the range in which the plurality of light spots are independently moved can be changed. Optical recording and reproducing device.