JPH06223397A - Optical recording-reproducing apparatus - Google Patents

Abstract

PURPOSE:To enable execution of a simultaneous access to a plurality of tracks by shifting by a rotary head positions of a plurality of spots imaged on an optical tape by deflecting a plurality of incident light fluxes and also by providing an image rotator on the optical path of a light source and the rotary head. CONSTITUTION:A plurality of beams from a semiconductor laser 1 are directed to a rotary head B rotating in the direction R around the optical axis Ax, through each optical element of a fixed part A and an image rotator(IR) 8. The IR 8 rotates at a speed of rotation of 1/2 of the head B, a prism 9 deflects the light flux incident on the head B and an objective lens 10 forms a plurality of spots spaced in the longitudinal direction of an optical tape 11, on this tape. A reflected light flux from the tape 11 proceeds along a reverse optical path and is converged on photodetectors 15 and 17 by beam splitters 3 and 13. Thereby execution of simultaneous recording or reproduction for a plurality of tracks is enabled by one rotation, the radius of rotation is lessened by using a wide rotational angle, and thus an apparatus can be made small in size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording / reproducing apparatus for recording and reproducing information on a recording medium by light,
The present invention relates to an optical recording / reproducing device suitable for a tape-shaped recording medium.

[0002]

2. Description of the Related Art A conventional optical recording / reproducing apparatus is generally one that records and reproduces information on a disk-shaped medium such as a compact disk, a video disk, or a magneto-optical disk.

In the above recording / reproducing apparatus, since the diameter of the light spot is narrowed down to the diffraction limit, further improvement in recording density cannot be expected. Therefore, the recording capacity of the medium depends on the recording area, but in the case of a disc-shaped recording medium, the size is also limited and the recording capacity is limited.

Therefore, it has been proposed to use a tape-shaped recording medium having a large recording area as a medium having a larger capacity.

[0005]

When recording / reproducing information on / from a tape-shaped recording medium, the head is rotated so as to traverse the tape in its width direction, as is adopted in a magnetic recording VTR. The method is desirable for increasing the recording / reproducing speed.

Further, in order to further improve the recording / reproducing speed, it is desirable to adopt a multi-beam system in which spots formed by a plurality of beams are scanned on different tracks.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a device for recording or reproducing information on a tape-shaped recording medium by light, and in particular, a plurality of It is an object of the present invention to provide a configuration suitable for a multi-beam method in which a plurality of tracks can be simultaneously accessed by a light beam.

[0008]

In order to achieve the above-mentioned object, an optical recording / reproducing apparatus according to the present invention deflects a plurality of light beams incident from a light source section by a deflecting member to the outside of the incident direction and is deflected. In a device for forming an image of a light flux as a plurality of spots on an optical recording medium via an objective lens, the light source unit is fixed, and the deflection member and the objective lens are rotated about the direction of the light flux incident on the deflection member. Provided on the head, in the optical path between the light source unit and the rotary head,
It is characterized in that an image rotator that rotates at half the rotational speed of the rotary head is provided.

[0009]

Embodiments of the present invention will be described below. Figure 1
[Fig. 3] shows an outline of an optical system of the optical tape system of the embodiment.

A magnetic film is formed on the surface of the optical tape, and the recording / reproducing apparatus records information by heat and magnetic field of light and reflects the same as in a generally used magneto-optical disk apparatus. The recorded information is reproduced by using the magnetic Kerr effect of time.

A plurality of beams emitted from the multipoint emission semiconductor laser 1 are made into parallel light fluxes by a collimator lens 2 and are once converged by a condenser lens 4 via a first beam splitter 3.

The servo lens 5 is driven in the optical axis direction and the direction orthogonal to the optical axis for focusing and tracking. The light flux emitted from the servo lens 5 enters the image rotator 8 via the relay lenses 6 and 7. The optical elements from the semiconductor laser 1 to the relay lens 7 are provided in the fixed portion A.

The light flux emitted from the image rotator 8 is reflected outside the optical axis of the incident light flux by the prism 9 provided in the rotary head B as a deflecting member. As shown in FIGS. 1 and 2, the rotary head B rotates about the optical axis Ax with respect to the fixed portion A in the R direction.

The reflected light beam from the prism 9 enters the objective lens 10 and forms a plurality of spots on the optical tape 11 as a recording medium, which are spaced apart in the longitudinal direction of the tape. Therefore, it is possible to record / reproduce on a plurality of tracks with one rotation.

The reflected light beam from the optical tape 11 becomes a parallel light beam through the objective lens 10 again, and the relay lens 6,
It is incident on the first beam splitter 3 via 7, the servo lens 5 and the condenser lens 4. The light beam reflected by the first beam splitter 3 has its polarization direction rotated by 45 degrees by the ½ wavelength plate 12, and the polarization beam splitter 1
It is separated into both P and S polarization components by 3.

P transmitted through the polarization beam splitter 13
The polarized light component is converted into the first light receiving element 15 by the condenser lens 14.
Focused on top. The S-polarized component reflected by the polarization beam splitter 13 is condensed by the condenser lens 16 on the second light receiving element 17.

Since the magnitude of the intensity of the polarized component changes depending on the direction of the magnetic field in the area where the spot is located on the optical tape, the reproduction signal from the optical tape is received by each light receiving element 1.
It is obtained by subtracting the outputs of 5, 17 by the subtracter 18. Further, each signal of the track error and the focus error is detected by using the output of at least one of the light receiving elements, and the servo lens is driven by an actuator (not shown) so as to eliminate these errors. In order to detect the error signal, it is necessary to divide the light receiving area of the light receiving element into a plurality of areas. However, since these are generally known as the technology of the magneto-optical disk device, detailed description thereof will be omitted here.

When the multi-beam method using a plurality of light beams as described above is adopted, if the light source is provided in the fixed portion and the prism 9 and the objective lens 10 for deflecting the light beams from the light source portion are arranged in the rotary head B, The positional relationship of the spots on the optical tape 11 changes as shown in FIG. 3 depending on the rotation angle. The spot B on the optical axis moves along the locus of rotation, but the positions of the off-axis spots A and C are exchanged during the rotation of 180 degrees. Here, the spots are arranged on adjacent tracks when passing through the center of the tape.

Therefore, if no measures are taken, if the rotation angle used for recording / reproducing is wide, the spot outside the optical axis does not trace on the track, and recording / reproducing cannot be performed. Only a very limited part can be used effectively. If the range of rotation angles that can be used is narrow and the width of the tape is constant, the radius of rotation must be increased, which causes a problem that the entire device becomes large.

Therefore, in the apparatus of the embodiment, an image rotator 8 is provided between the relay lens 7 and the prism 9, and the image rotator 8 is attached to the rotary head B.
A rotation mechanism that rotates at half the speed is provided. As a result, the positional relationship of the spot with respect to the tape does not change due to the rotation as shown in FIG. 4, and a relatively wide rotation angle can be used. Therefore, even if the turning radius is small, a predetermined tape width can be dealt with, and the device can be downsized.

When the image rotator 8 is arranged in the diverging / converging light beam, aberrations such as astigmatism are generated, so it is desirable to arrange it in the parallel light beam. In the embodiment, it is provided between the relay lens 7 and the prism 9, but it may be provided at any part between the collimator lens 2 and the prism 9 as long as the light flux is substantially parallel.

In the above embodiments, the magneto-optical recording method has been described as an example. However, if the recording method on the tape is optical recording, the rotation of the image rotator can be similarly applied to other methods such as the phase change recording method. Thus, the arrangement interval of the light spot rows can be made constant.

[0023]

As described above, according to the present invention, a larger amount of information can be collectively managed by using a tape-shaped recording medium having a storage capacity larger than that of an optical disc. Also, by adopting the multi-beam method, the speed of recording / playback is improved, and by providing an image rotator, a wide range of rotation angles that can be used is secured, and the radius of rotation of the rotating part is made small to make the device compact. Can be

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an optical system showing an outline of an optical tape system of an example.

FIG. 2 is a plan view of the rotary head shown in FIG.

FIG. 3 is an explanatory diagram showing changes in the positional relationship of spots on a recording surface when there is no image rotator.

FIG. 4 is an explanatory diagram showing changes in the positional relationship of spots on a recording surface when an image rotator is provided.

[Explanation of symbols]

 A ... Fixed part B ... Rotating head 1 ... Semiconductor laser 2 ... Collimating lens 3 ... Beam splitter 4 ... Condensing lens 5 ... Servo lens 6, 7 ... Relay lens 8 ... Image rotator 9 ... Prism 10 ... Objective lens 11 ... Tape 11 Optical tape 12 1/2 wave plate 13 Polarizing beam splitter 14 Condenser lens 15 Light receiving element 16 Condenser lens 17 Light receiving element 18 Subtractor

Claims (1)

[Claims] 1. A light source section for generating a plurality of light fluxes, a deflection member for deflecting the plurality of light fluxes incident from the light source section out of the incident direction, and the deflected light fluxes as a plurality of spots on an optical recording medium. A rotary head that has an objective lens for forming an image, is rotatably provided about the direction of the incident light beam, and moves the position of the spot, and is provided in an optical path between the light source unit and the rotary head. And an image rotator that rotates at half the rotation speed of the rotary head.