JPH0447475Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a backlash absorption structure in a rack and pinion mechanism that can be advantageously implemented in a disc reading device, such as a compact disc player or a video disc player.

Background technology For example, in a compact disc player,
Due to the backlash of the rack and pinion mechanism for power transmission, the driving response of the optical pickup is reduced, which may cause tracking errors. Therefore, a typical prior art technique for absorbing backlash in rack and pinion mechanisms and obtaining high responsiveness is to overlap a pair of pinions 1 and 2 coaxially, as shown in FIGS. 4 and 5. These pinions 1 and 2 are each provided with an arc-shaped spring 3 whose both ends are locked, and the spring force of this spring 3 allows the teeth 1a and 2a of the pinions 1 and 2 to be easily engaged with these pinions 1 and 2. 4 teeth 4a are sandwiched from both ends to absorb backlash between the pinions 1, 2 and the rack 4.

In another prior art, as shown in FIG. 6, a pair of racks 5 and 6 are stacked on top of each other, one rack 5 is fixed and the other rack 6 is movable.
Coil-shaped springs 7 are provided at both ends of these racks 5 and 6, and the spring force of these springs 7 causes the teeth 5a and 6a of the racks 5 and 6 to mesh with these racks 5 and 6. It is held between both sides of the teeth 8a of the pinion 8, thereby absorbing the backlash between the racks 5, 6 and the pinion 8.

Such a backlash absorption structure of the rack and pinion mechanism complicates the gear structure and increases production costs. Furthermore, it is not possible to make the pinions 1 and 2 and the racks 5 and 6 thinner.

Problems to be solved by the invention The present invention solves the above-mentioned technical problems and provides a backlash absorption structure for a rack and pinion mechanism that has a simple structure and can obtain high responsiveness. It is.

Means for Solving the Problems The present invention comprises a worm attached to the shaft of a motor that rotates reciprocatingly, a worm wheel that meshes with the worm, a pinion that rotates as the worm wheel rotates, and a worm wheel that meshes with the worm. Easy to mesh,
The rack is provided with a holder that is slidably supported on a guide rod, and a spring that is fixed at both ends to the holder and a fixed wall, respectively, and the spring moves the holder in the direction in which the rack extends. This is a backlash absorption structure in a rack and pinion mechanism characterized by being biased by a spring.

Function According to the present invention, the holder that slides along the guide rod is biased by the spring in the direction in which the rack extends, so the rack and pinion always move in a meshed state, and the structure is improved. A simple and thin battery absorption structure can be achieved. Also,
Since a worm and a worm wheel are used to rotate the pinion, the pinion rotates due to the easily applied spring force, and this is not transmitted back to the motor, thus causing the motor rotor to idle. This will prevent you from doing anything. Further, with the above configuration, even when the motor rotates back and forth, the pinion and the rack are always in contact with each other at a predetermined single tooth surface, so that backlash does not occur.

Embodiment FIG. 1 is a plan view of an embodiment of the present invention, and FIG. 2 is a left side view of FIG. 1. A compact disk 10 (hereinafter referred to as disk) is mounted on a turntable 12 that is rotationally driven by a disk rotation motor 11, and is fixed to the turntable 12 by a cylindrical permanent magnet piece 13 or the like. A so-called optical pickup 14, which is a device for optically reading signals recorded on the disk surface 10a, is arranged below the disk 10 (on the back side of the paper in FIG. 1 and on the lower side in FIG. 2). An irradiation hole 15 is formed in the optical pickup 14 for irradiating laser light toward the disk surface 10a. The optical pick-up 14 is held by a pick-up holder 16 that is roughly in the shape of an inverted U, and the legs 16a and 16b of the pick-up holder 16 are connected to a pair of guide rods 17 and 18 that extend parallel to the top and bottom of FIG. It is movably guided by. With this pick-up holder 16 and guide grooves 17 and 18, the optical pick-up 14
can move back and forth in the radial direction.

The mechanism for moving the pick-up holder 16 along the guide rods 17 and 18 includes a pick-up feeding motor 20 that can rotate forward and backward, a worm 21 that is rotationally driven by the motor 20, and a worm wheel 22 that meshes with the worm 21. and worm foil 2
2, and a rack 24 that meshes with the pinion 23.
A rack 24 is formed on one side of the leg 16a. A locking piece 25 is provided on the other side of the leg portion 16a.
is formed, and a coil-shaped spring 2 is attached to this locking piece 25.
One end of 6 is locked. The other end of the spring 26 is
It is fixed to a fixed wall 27 provided on the outer side of the disk 1 in the radial direction. Due to the spring force of this spring 26, the leg portion 16a is moved so that the pick-up holder 1
6 is always elastically biased radially outward of the disk 10 as indicated by arrow B along the guide rods 17, 18. The spring force of the spring 26 is selected to a value that prevents an excessive load from being applied to the motor 20 when the pick-up feeding motor 20 rotates, and at the same time allows the pick-up holder 16 to move.

Referring also to Figure 3, pinion 23 and rack 2
The driving state with 4 will be explained. Hikari pick up 14
When the disk 10 is at rest, the rack 24 is always resiliently biased outward in the radial direction of the disk 10 as indicated by the arrow B by the spring 26. Therefore, the teeth 23a of the pinion 23 and the teeth 24a of the rack 24 are always in point contact at the intersection 30 between the pitch circle 28 of the pinion 23 and the pitch line 29 of the rack 24. Therefore, the pinion 23 is always resiliently biased in the direction shown by arrow D.

The pick-up feed motor 20 drives the worm 21 and the pinion 2 via the worm wheel 22.
3 is rotated in the positive direction shown by arrow C, the rack 24 resists the spring force of the spring 26 and rotates the pinion 2.
3 and the arrow A in the state of meshing at the intersection 30.
It moves inward in the radial direction of the disk 10 as indicated by . Therefore, the optical pickup 14 is moved inwardly in the radial direction of the disk 10 along the guide rods 17, 18 in a minute manner in conjunction with the rack 24. At this time, laser light is emitted from the irradiation hole 15 of the optical pickup 14 to the disk rotation motor 1.
Disk surface 1 of disk 10 rotated by
0a, and the signals recorded on the disk surface 10a are optically read sequentially.

Next, by the pick-up feed motor 20,
When the pinion 23 is rotationally driven in the opposite direction indicated by the arrow D via the worm 21 and the worm wheel 22, the rack 24 moves outward in the radial direction of the disk 10, indicated by the arrow B, with a small amount of feed. do.
At this time, the rack 24 is able to travel back in the radial direction outward of the disk 10 at the intersection 30 with the pinion 23 without rattling due to the spring force of the spring 26. can.

Since the backlash between the pinion 23 and the rack 24 is absorbed by the spring 26 in this way, the responsiveness of the rack 24 to the rotational drive of the pinion 23 is extremely high, and therefore the high responsiveness when the optical pick-up 14 is slightly fed is increased. achieved. Therefore, even if the disk 10 is eccentric or warped, tracking errors can be prevented by minutely moving the optical pickup 14, which has high responsiveness. Also, as shown in the prior art, the rack and pinion are
Since it is not necessary to stack the rack and pinion mechanism, the structure of the rack and pinion mechanism can be simplified and thinned, and the production cost can be reduced. Furthermore, by using the worm 21 and the worm wheel 22 as a drive transmission mechanism between the pick-up feed motor 20 and the pinion 23, the rotation of the pinion 23 caused by the spring force of the spring 26 is transferred to the motor 2.
Therefore, the rotor of the motor 20 is prevented from idling.

In the embodiment described above, the fixed wall 27 to which one end of the spring 26 is fixed is provided on the radially outer side of the disk 10 than the locking piece 25 of the leg portion 16a. It may also be provided on the radially inward side. At this time, the rack 24 is always resiliently urged inward in the radial direction of the disk 10 by the spring 26, thereby absorbing backlash.

In the embodiment described above, one end of the spring 26 is fixed to one leg 16a of the pick-up holder 16, but it may be fixed to the other leg 16b.

The backlash absorption structure in a rack and pinion mechanism according to the present invention can be used not only in relation to disc reading devices such as compact disc players and video disc players, but also in a wide range of technical fields related to rack and pinion mechanisms. can.

Effects As described above, according to the present invention, the rack meshing with the pinion is biased by the spring in one direction in which the rack extends, thereby achieving high responsiveness of the rack with a simple configuration. This makes it possible to absorb backlash in rack and pinion mechanisms.

In other words, according to the present invention, it is possible to achieve a simple, thin, and bumpy absorption structure, and the rotation due to the spring force is not reversely transmitted to the motor, so that the rotor of the motor does not idle. This will prevent you from doing anything. Furthermore, even when the motor rotates reciprocally, the pinion and rack are always in contact with each other at a predetermined single tooth surface, so that backlash does not occur.

[Brief explanation of the drawing]

FIG. 1 is a plan view of one embodiment of the present invention, FIG. 2 is a left side view of FIG. 1, FIG. 3 is an enlarged view of the meshing portion of the pinion 23 and rack 24, and FIGS. The figure is a diagram for explaining the prior art. 1, 2, 8, 23...pinion, 4, 5, 6,
24...Rack, 14...Light Pickup, 21
...Worm, 22...Worm foil, 26...
...Spring.

Claims (1)

[Scope of utility model registration request] A worm attached to the shaft of a motor that rotates reciprocally, a worm wheel that meshes with the worm, a pinion that rotates as the worm wheel rotates, a rack that meshes with the pinion, and a guide rod provided with the rack. The rack has a holder slidably supported by the rack, and a spring fixed at both ends to the holder and a fixed wall, respectively, and the spring biases the holder in the direction in which the rack extends. A backlash absorption structure in a rack and pinion mechanism characterized by: