JPH04222930A - Recording and reproducing device for disk-line recording medium - Google Patents

Abstract

PURPOSE:To accurately correct the optical axis of an optical head with simple constitution by inclining a feeding shaft for guiding the optical head by using a new mechanism. CONSTITUTION:In a recording and reproducing device provided with the feeding shaft 14 for guiding the optical head 26 which performs recording/reproducing on a disk, 1st and 2nd cam members 17 and 18 are respectively provided at both ends of the shaft 14. By adjusting the inclination of the shaft 14 by the rotation of the members 17 and 18, the optical axis of the optical head 26 with respect to the disk is corrected. The optical axis is accurately corrected according to the warpage of the disk with the number of parts smaller than that of a conventional device.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording/reproducing apparatus for a disc-shaped recording medium, and more particularly to an optical axis correction mechanism of an optical head for a disc-shaped recording medium.

0002

2. Description of the Related Art In general, a recording/reproducing device for a disc-shaped recording medium (disk) is driven to rotate while the disc is placed on a turntable, and a laser beam is directed from an optical head (optical pickup) onto the recording surface of the disc. The device is configured to be irradiated with light and thereby read or write signals.

[0003] In such recording and reproducing devices, especially those using large-diameter disks, the disk placed on the turntable is deformed by its own weight, that is, the outer periphery of the disk warps downward. Therefore, it is necessary to correct the optical axis of the optical head accordingly.

FIGS. 9 and 10 show an example of an optical axis correction mechanism of an optical head in a conventional recording/reproducing apparatus for a disc-shaped recording medium of this type.

In the figure, reference numeral 1 denotes a main chassis. A spindle motor 2 is mounted and fixed on this main chassis 1, and a disk-shaped recording medium, ie, a disk D, is mounted on a turntable 3 attached to the spindle shaft of this spindle motor 2.
is placed and rotated.

4 is a sub-chassis, and this sub-chassis 4
is supported by the main chassis 1 via support shafts 5 protruding from both sides of the main chassis 1 so as to be rotatable, that is, tiltable, in the vertical direction. A feed shaft 6 is fixed to the sub-chassis 4 in the radial direction of the disk D, and an optical head 7 is supported so as to be movable along the feed shaft 6.

The optical head 7 irradiates a laser beam toward the recording surface of the disk D from an objective lens 8 provided on its upper surface, thereby reading or writing signals. Further, this optical head 7 is connected to a feed shaft 6 by a predetermined feed mechanism (for example, a linear motor), although not shown.
The recording track of the disk D is thereby moved in the disk radial direction so that signals can be read or written in accordance with the recording track of the disk D.

In the conventional device configured as described above, when the disk D warps downward as shown in FIG. By tilting around the center and also tilting the optical head 7 integrally, the disk D
The optical axis of the laser beam emitted from the objective lens is adjusted to be always perpendicular to the optical head, that is, the optical axis of the optical head is corrected.

[0009]

[Problems to be Solved by the Invention] In the conventional device configured as described above, a sub-chassis is used as a component for optical axis correction. Because the same level of parts precision is required for all parts, it is difficult to ensure the accuracy of the entire device, and the two chassis have problems that prevent the device from becoming more compact. .

[0010] The present invention has been made in view of the above points.
It is an object of the present invention to provide a device capable of correcting the optical axis of an optical head with a simpler and more compact configuration.

[0011]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides cam members at both ends of a feed shaft that guides the movement of an optical head, and adjusts the inclination of the feed shaft by rotating the cam member. However, the optical axis of the optical head relative to the disk is corrected.

0012

[Operation] In the device of the present invention configured as described above,
The optical axis correction of the optical head, which was conventionally done using a sub-chassis, is now done by tilting the feed axis itself with a cam member, eliminating the need for a sub-chassis, resulting in a reduction in the number of parts and further compactness. can be achieved.

[0013]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 8.

FIGS. 1 and 2 show the basic configuration of the present invention. In the figure, 11 is a chassis, and this chassis 1
A spindle motor 12 is fixed to 1, and a disk D is placed on a turntable 13 attached to the spindle shaft of this spindle motor 12 and rotated.

Further, a feed shaft 14 is arranged on the chassis 11 in the radial direction of the disk D. The feed shaft 14 is vertically movable and rotatably supported by bearings 15 and 16 protruding from the upper surface of the chassis 11 at both ends thereof.

Cams 17 and 18 (hereinafter referred to as a first cam and a second cam, respectively) are fixed to both end portions of the feed shaft 14, respectively. These first cams 17 and second cams
The cams 18 are so-called plate cams, and their respective peripheral edges abut against pedestals 19 and 20 formed on the upper surface of the chassis 11. In particular, in this example, the first cam 17
and the second cam 18 are mounted so that they are in opposite phases to each other.

A ring-shaped member 21 is rotatably fitted to a predetermined portion of the feed shaft 14, and a tension coil spring 22 is stretched between the ring-shaped member 21 and the upper surface of the chassis 11. , this tension coil spring 22
The force causes the feed shaft 14 to be pulled downward, so that the cams 17 and 18 are always pressed against the cradle portions 19 and 20 so as not to separate from them.

Both cams 17 and 18 are rotated by an electric mechanism. That is, a gear 23 is fixed to one end of the feed shaft 14, and a worm 25 attached to the rotating shaft of a cam drive motor 24 meshes with the gear 23. The cam drive motor 24 is movably attached to the chassis 11 and rotates a worm 25 in response to a signal from the tilt servo circuit, and the rotation of the worm 25 is transmitted to the feed shaft 14 via the gear 23. Both cams 17 and 18 are rotated together with this.

As described above, the optical head 26 is supported on the feed shaft 14, which is supported by the chassis 11 via both cams 17 and 18, so as to be movable along its axial direction. This optical head 26 irradiates a laser beam toward the recording surface of the disk D from an objective lens 27 provided on its upper surface to read or write signals.
is moved in the disk radial direction along the feed shaft 14 by a predetermined feed mechanism 28 configured between the chassis 11,
Signals are read or written in accordance with the recording track of the disk D.

[0020] In this embodiment of the apparatus constructed as described above, when the disk D warps downward as shown in FIG. 2, the tilt servo circuit detects this and drives the cam drive motor 24, thereby Both cams 17 are integrated with the feed shaft 14.
, 18 are rotated. At this time, since the first cam 17 and the second cam 18 are in opposite phases, the feed shaft 14 is tilted so that when one end goes up, the other goes down, and the optical head 26 also tilts accordingly. As a result, the optical axis is corrected so that the laser beam emitted from the objective lens 27 always strikes the disk D perpendicularly.

The apparatus of this embodiment as described above has an advantageous structure in terms of accuracy and number of parts compared to the conventional apparatus. That is, in this example device, the feed shaft 14 has the two functions of guiding the movement of the optical head 26 and tilting it, so that the feed shaft itself can be used without the need for the sub-chassis used in the conventional example described above. Optical axis correction is performed by tilting, and as a result, the number of large parts that require precision is reduced by one, making it easier to ensure the accuracy of the entire device due to the simpler configuration. This is also effective in making the device more compact.

Furthermore, in the configuration shown in this example, by making the shapes of the first cam 17 and the second cam 18 asymmetrical, it is possible to set the center point of the inclination of the optical head 26 at an optimal position. becomes.

That is, in the device as described in FIGS. 1 and 2, in which the feed shaft 14 is tilted by the rotation of the cams 17 and 18 attached to both ends thereof, both cams 17 and 18, as shown in FIG. If the optical head 18 has a symmetrical shape, the center point of the inclination of the optical head 26 will be the midpoint between both the cams 17 and 18. In other words, as shown in FIG. 4, if the displacements of the first cam 17 and the second cam 18, which are rotated in opposite phases to each other, are equal, the feed shaft 14 will be tilted about a point exactly midway between the two cams 17 and 18. will be done.

On the other hand, as shown in FIG.
and the second cam 18 have an asymmetrical shape (in this example, as shown in FIG.
As shown in the example of FIG. Figure 1
If applied to the configuration shown in FIG. 2, it will be set closer to the inner circumference of the disk. In this way, by appropriately selecting the shape, that is, the amount of displacement of both cams 17 and 18, the optical head 2 can be adjusted according to the design.
6 can be set at any position.

The center point of the inclination of the optical head 26 is the inflection point of the disk D, that is, the point at which warping begins (generally, this inflection point is located slightly closer to the outer circumference than the center of the disk supported by the turntable). By adjusting to
The optical head 26 can be tilted to accurately follow the warpage of the disc D, and therefore the optical axis can be corrected to more accurately correspond to the warped surface of the actual disc.

Furthermore, in the apparatus shown in FIGS. 1 and 2, by configuring the first cam 17 and the second cam 18 to rotate independently, the perpendicularity of the optical axis with respect to the disk D can be adjusted. In addition, the distance between the optical head 26 and the disk D can be kept constant.

In this case, a first cam 17 and a second cam 18 are rotatably attached to both ends of the feed shaft 14 as shown in FIG. Gears 23 are fixed, and worms 25 attached to the rotating shafts of cam drive motors 24 are meshed with the gears 23, respectively. By driving each cam drive motor 24 using a predetermined tilt servo circuit to rotate the first cam 17 and the second cam 18 separately,
As is clear from FIG. 8, the feed shaft 14 can be tilted while keeping the distance L between the optical head and the disk constant at all times, making it possible to perform optical axis correction with higher precision.

[0028]

As explained above, the device of the present invention adjusts the inclination of the feed shaft by rotating the cam member and adjusts the optical axis of the optical head with respect to the disk-shaped recording medium, so it is better than the conventional device. This simplifies the configuration, which makes it easier to ensure the accuracy of the entire device, and has a great effect in making the device more compact. Furthermore, in the configuration of the present invention, by changing the amount of displacement of both cam members, the center of inclination of the optical head can be set at the optimal position, so it is possible to perform optical axis correction that more accurately corresponds to the warped surface of the disk-shaped recording medium. . Furthermore, in the configuration of the present invention, if both cam members are rotated independently, accurate optical axis correction can be performed while always keeping the distance between the optical head and the disc-shaped recording medium constant. Enables more accurate optical axis correction.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of an embodiment of the present invention.

FIG. 3 is an explanatory diagram when both cams have a symmetrical shape.

FIG. 4 is an explanatory diagram of the cam in FIG. 3;

FIG. 5 is an explanatory diagram of an example in which both cams have an asymmetrical shape.

FIG. 6 is an explanatory diagram of the cam in FIG. 5;

FIG. 7 is an explanatory diagram of an example in which both cams are rotated independently.

FIG. 8 is an explanatory diagram of the example of FIG. 7;

FIG. 9 is a perspective view showing the configuration of a conventional example.

FIG. 10 is an explanatory diagram of a conventional example.

[Explanation of symbols]

D Disc (disc-shaped recording medium) 11 Chassis 14 Feed axis 17 First cam 18 Second cam 26 Optical head

Claims (1)

[Claims] 1. A cam member is provided at each end of a feed shaft that guides the movement of an optical head for recording/reproducing on a disc-shaped recording medium, and the inclination of the feed shaft is adjusted by rotation of the cam member. A recording/reproducing apparatus for a disc-shaped recording medium, characterized in that the optical axis of the optical head with respect to the disc-shaped recording medium is corrected.