JPS6230217Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a feeding system for an optical head in a video disc player, and more particularly to a related mechanism between a drive screw shaft for moving an optical system and an optical system moving block.

Various video disc systems have been proposed as a means of providing video information, but optical video disc systems are especially easy to reproduce discs at low cost, and because of non-contact readout, there is no wear on the disc or pickup section. It is attracting particular attention due to its excellent performance and functionality, as it is capable of high-quality reproduction of video and audio, and is also capable of various functions such as slow motion and random access.

Incidentally, an optical disc player requires a tracking servo that can accurately follow a minute pattern with a tracking pitch of approximately 1.5μ, and various detection devices for this tracking servo have been devised. The optical system is configured as shown in FIG. 1, for example. That is, the laser beam emitted by the laser tube 1 is transmitted to the grating 2.
Utilizes the first-order diffracted light produced by the beam, and generates three beams together with the main beam. Then, the beam is transmitted from a spot lens 3 to a fixed reflecting mirror 4,
5, the beam passes through a Wollaston prism 6, is further converted into a circularly polarized light beam by a quarter-wave plate 7, and is further provided with a tracking mirror 8 and a reproduction device that shakes the beam in the radial direction to track the track on the disk 11. In order to eliminate time axis fluctuations in the signal, the beam is guided to an objective lens 10 by a tangential mirror 9 that swings the beam in the tangential direction, and is focused on the signal recording surface of the disk 11. Then, the reflected beam, which is modulated by the pit of the disk 11 and totally reflected by the reflective film and whose rotational direction of circularly polarized light is reversed, follows the optical path in the opposite direction and is 1/1/2 again.
It passes through a four-wavelength plate 7, is converted into linearly polarized light in a direction perpendicular to the incident beam, and then passes through a Wollaston prism 6, reaches a photodiode 13 via a cylinder lens 12, and is detected.

As shown in FIG. 2, the optical system is linearly moved in the radial direction of the disk 11 to perform linear tracking from the inner track Ti to the outer track Tn.

Incidentally, the moving speed of such an optical system is such that during normal playback, all tracks on the disk are tracked in, for example, 30 minutes, while during random access, data is transferred at an extremely fast speed of, for example, 5 seconds. Therefore, in order to easily realize two types of optical system movement speeds with different speeds, two motors 14, 1 with different gear ratios are used as shown in FIG.
5 is used to rotate the feed screw shaft 16 for moving the optical system block, and by screwing the nut 18 integrated with the optical system block 17 onto the screw shaft 16, the motor 14 or 15 can be rotated. A method is adopted in which the feed speed of the optical system block 17 is selected accordingly.

However, the nut 1 of the feed screw shaft 16 and the optical system block 17 rotated by such a motor.
8, the feed screw must be installed parallel to the advancing direction of the optical system block 17, but this inevitably results in some error. In particular, since the feed screw shaft 16 is formed into a long rod shape that is pivotally supported at both ends, even if the screw itself is formed accurately, even if there is a slight misalignment between the pivot points at the two ends that are separated in the axial direction. This will cause the screw shaft 16 to tilt.

In addition, in the conventional structure in which the female screw nut 18 integrated with the optical system block 17 is screwed into the feed screw shaft 16 from the screw shaft end side, the above-mentioned It is necessary to thread the female screw 18 and assemble the optical system block 17 to the feed screw shaft 16. Therefore,
Not only is the assembly work complicated, but especially the feed screw shaft 1.
6 is difficult to assemble accurately, and the workability is poor.

Moreover, if there is some error in the feed screw shaft 16, there is a risk of play in the female screw 18 on the optical system block 17 side. About the aforementioned
When performing linear tracking on a pattern with a fine tracking pitch such as 1.5μ, it causes tracking deviation, making it impossible to obtain a high-quality reproduction signal.

Therefore, the present invention has been devised in view of the above-mentioned circumstances, and it is an object of the present invention to provide a feeding device for a video disc player that can solve the above-mentioned drawbacks.

That is, an object of the present invention is to be able to absorb some errors in the feed screw shaft and always realize stable linear tracking.

Furthermore, this invention makes it extremely easy to attach and detach the passive screw part provided on the optical system block side to the feed screw shaft, especially when the feed screw shaft is arranged in a uniquely accurate axially supported state. The object of this invention is to enable easy and accurate screwing of the passive screw portion on the block side, thereby improving serviceability.

That is, the feeding device of the present invention moves the optical head from a rotary male screw shaft disposed parallel to the radial direction of the disk, and a half nut that meshes with the male screw shaft and is attached to the moving block of the optical head. The half nut is fitted into a housing fixed to the moving block to restrict movement in the axial direction of the male threaded shaft, and is held so as to be movable only around the axis and in the radial direction. It is characterized by:

Hereinafter, the present invention will be explained with reference to the drawings.

First, FIG. 4 is an exploded perspective view of the main parts of the feeding section of the optical system block to which the feeding device of the present invention is applied. 20 is a laser tube; 2
Reference numeral 1 denotes a cover in which an optical system for guiding the laser beam emitted from the tube 20 to the disk surface is built-in. Reference numeral 22 denotes an objective lens, which is an optical head that projects the laser beam onto the lower surface of the disk and detects the reflected beam. Reference numeral 23 denotes a moving block for the optical system, in which the optical system elements such as the laser tube 20, cover 21, objective lens 22, etc. are integrally arranged. Roller grooves 27 and 28 are formed in a V-groove shape and have cross rollers (not shown) interposed between them and the rails 25 and 26 as sliding means. Further, a half nut 29 is attached to the lower surface side of the moving block 23.

The base block 24 is attached to a mechanical chassis (not shown), and the guide rail 25,
26 supports the moving block 23 so as to be movable in the radial direction of the disk, and also supports a motor 30 for rotating the disk and a rotary male screw shaft 31 for moving the moving block 23 of the optical system. ing. Each guide rail 25, 26 has V-shaped roller grooves 25A, 26 so that the above-mentioned cross roller can be arranged between each roller groove 27, 28 of the moving block.
A is formed.

Both ends 31A of the rotating male screw shaft 31,
The area around 31B is rotatably supported by bearings 32 and 33 formed on the base block 24, and a wheel gear 34 is attached near one end 31A. Further, 35 is a high rotation motor for random access, etc., and 36 is a low rotation motor for manual tracking. Each of these motors 35, 36 is connected to each clutch 35A, 36A.
The drive wheel gears 37 and 38, which are pivotally connected to the clutch output shaft, connect to the wheel gear 3 via
4 is intermeshingly connected. By meshing the half nut 29 disposed on the moving block 23 with the rotating male screw shaft 31, the optical system can be moved for linear tracking by the rotational force of the motor 35 or 36. .

By the way, in the present invention, the half nut has a structure as shown in FIGS. 5 and 6, for example.

That is, the half nut 29 is formed as a semicircular screw at the lower end of the vertical portion 40A of the T-shaped half nut block 40. Spring retaining holes 43 and 44 are formed on the upper surface of the horizontal portion 40B of the half nut block 40, in which one end of each spring 41 and 42 is abutted and engaged, and the nut supported by the moving block 23 is A screw hole 46 into which a pulling screw shaft 45 can be screwed is threaded. Further, 47 is a housing for holding a half nut, and has a box-shaped nut insertion recess 48 that is open at the top, and this recess 4
An opening 49 into which the vertical portion 40A of the half nut block 40 is inserted is inserted through the center of the bottom wall 48A of the nut block 8.
Further, screw mounting holes 50A and 51A protrude outward on both sides of the upper end. Flange portions 50 and 51 are provided. The housing is provided with a rib-shaped reinforcing body 4 as shown in FIG. 6B.
By providing 7A, the half nut can be held stably.

When the half nut block 40 is fitted into the recess 48 of the housing 47, the vertical portion 4
0A is projected downward from the housing 47 through an opening 49. Half nut block 40 like this
When the housing 4 is assembled to the housing 47,
Screw mounting holes 50A of flange parts 50 and 51 of 7,
The mounting screws 52 and 53 are inserted into and engaged with the screw holes 54 and 55 of the moving block 23, and fixed to the lower surface 23A of the moving block 23. At this time, springs 41 and 42 are elastically interposed between the spring holding holes 43 and 44 of the half nut block 40 and the lower surface 23A of the moving block. As a result, the half nut block 40 is inserted into the housing 48 with the spring 41,
42, it is elastically energized downward, that is, in the protruding direction.

Therefore, in this state, as shown in FIG. 7, the half nut 29 is engaged with the rotating male threaded shaft 31 from above in the figure. Therefore, when the screw shaft 31 is rotationally driven, the moving block 23 is moved along the screw shaft 31 in the screw axis direction, that is, in the radial direction of the disk. Furthermore, in the state shown in FIG. 7 above, the pulling screw shaft 45 is left in a free state without being screwed into the screw hole 46 corresponding to this screw shaft, and is not pushed upward. ing. Further, as shown in FIG. 8, when the pulling screw shaft 45 is screwed into the screw hole 46 of the half nut block 40, the half nut block 40 gradually moves inside the housing 47 along the screw shaft 45. The half nut 29 is pulled upward, and the half nut 29 is attached to the rotating male threaded shaft 3.
1 and detached from the rotary male threaded shaft 31.

In the above configuration, the half nut 29 on the optical system moving block 23 side with respect to the rotating male screw shaft 31
is screwed into a part of the outer periphery of the shaft 31 by being press-fitted from the outer radial direction. Therefore, this half nut 29 can be easily screwed together by assembling the rotating male screw shaft 31 and then assembling the moving block 23 from above, and the intended purpose can be fully achieved.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an overview of the video disk reproducing optical system, FIG. 2 is a plan view schematically showing the relationship between the disk and the optical head, FIG. 3 is a plan view schematically showing the optical system drive device, and FIG. 4 is a schematic exploded perspective view of an optical system moving device to which the feeding device of the present invention is applied, FIG. 5 is an exploded perspective view of the main parts, and FIG. 6 is an assembled perspective view of the main parts. Corresponding to the figure, B shows a modified example. FIG. 7 is a front view, and FIG. 8 is a front view of the half nut in a detached state. 11... Disk, 23... Optical system moving block, 24... Base block, 29... Half nut, 31... Rotating male screw shaft, 35, 46... Motor, 40... Half nut block, 40A
...Vertical part, 40B...Horizontal part, 41, 42...
Spring, 43, 44... Spring holding hole,
47...Housing, 48...Nut insertion recess,
49...Opening.

Claims (1)

[Scope of utility model registration request] A rotary male threaded shaft disposed parallel to the radial direction so as to move the optical head in the radial direction of the disk, and a half nut meshed with the male threaded shaft and attached to the moving block of the optical head. The half nut is fitted into a housing fixed to the moving block to restrict movement in the axial direction of the male threaded shaft, and is held so as to be movable only around the axis and in the radial direction. A feeder for a video disc player featuring: