JPS6120658Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention is a disk player such as a video disk player that moves and operates a pick-up that constitutes a disk signal detection section that reads out video signals and other information signals from a disk on which the above information signals are recorded. This invention relates to a pick-up feeding device for a player.

Various video disk systems have been proposed as a means of providing video information. Among them, optical video disk systems are easy and inexpensive to reproduce, and because of non-contact readout, there is no wear on the disk, and the optical video disk system is It is attracting particular attention due to its excellent performance and functionality, including the ability to record and play back high-quality audio and many functions such as slow-motion random access.

Incidentally, an optical disc player requires a tracking servo that can accurately follow a fine pattern with a tracking pitch of approximately 1.5 μm, and various detection devices for this tracking servo have been devised. One of the most practical and reliable methods at present is a method using 3-spots. In this method, the laser beam emitted by the laser tube 1 uses the first-order diffracted light produced by the grating 2, and generates three beams together with the main beam, using an optical system as shown in Figure 1, for example. let Then, the beam passes through a Wollaston prism 6 through a spot lens 3, fixed reflecting mirrors 4 and 5, and then is converted into a circularly polarized light beam by a quarter-wave plate 7, and further traces a track on the disk. The beam is guided to the objective lens 10 by a tracking mirror 8 that swings the beam in the radial direction to eliminate time axis fluctuations in the reproduced signal, and a tangential mirror 9 that swings the beam in the tangential direction to eliminate time axis fluctuations of the reproduced signal, and is focused on the signal recording surface of the disk 11. Ru. The reflected beam is modulated by the pit of the disk 11, totally reflected by the reflective film, and the direction of rotation of the circularly polarized light is reversed.
Retracing the optical path and passing through the 1/4 wavelength plate 7 again,
converted into linearly polarized light perpendicular to the incident beam,
This time, the light passes through the Wollaston prism 6 and reaches the photodiode 13 via the cylinder lens 12, where it is detected. In order to detect whether the tracking is correct or incorrect on the actual video disc 11, it is carried out as shown in FIG.

That is, the angle formed by the three spots of the main beam A and each of the radial beams E and F must always be constant with respect to the tracking movement line. 2A is shifted to the left in the figure, FIG. 2B is normal, and FIG. 3C is shifted to the right. In order to maintain this constant angle, a linear tracking mechanism that slides perpendicularly to the track T or a mechanism equivalent thereto must be provided.

FIG. 3 is a diagram schematically showing the outline of the linear tracking mechanism. In the linear drive system shown in FIG. The optical system is accessed by a slider 14 that is linearly reciprocated by rollers 13a, 13b, 13c, and 13d so as to be slid in a straight line.

However, this method requires highly precise rollers and their guides due to their structure, and also requires high precision in terms of processing and assembly.

In addition, when relying on the rotary drive system shown in FIG. 3B, an appropriate fulcrum P is provided, and an arm with an arm length r is used to move the pickup optical system around the fulcrum P on the inner track Ai. It can be moved from the center to the outer track Ao. This method has the advantage of being simple in construction because it only requires the arm, but since the pick-up optical system moves on an arc centered on the fulcrum P,
The inner track is set at a certain angle to the above track.
It becomes impossible to maintain all of the tracks Ao on the outer circumferential side from Ai.

The present invention has been proposed in view of the above-mentioned conventional situation, and is an attempt to realize a pick-up feeding device with a simple configuration and at low cost. That is, in the pick-up feeding device of the present invention, a link arm is pivotally connected to the free end of a link lever having a fulcrum at one end, a pick-up is mounted on the tip of the link arm, and a guide sliding contact portion is provided. The sliding contact portion has a guide plate that is slidably guided, and the pickup is reciprocated along the guide plate by rotation of the link lever.

Hereinafter, one embodiment of the present invention shown in FIGS. 4 and 5 will be described. In addition, FIG. 4 is a schematic plan view, and FIG. 5 similarly shows a side view.

In these figures, reference numeral 14 is a rotary link, which is rotatable about one end 14A of the link as a rotation center O. A passive gear 15 is carved on the outer peripheral edge of the one end 14A, and this gear 15 meshes with a drive gear 17 operated by a motor 16. Further, the rotation center O is arranged so as to coincide with the center of the video disk 18, and for example, as shown in FIG. 5, one end 1 of the link lever 14
The shaft hole 14C opened in the shaft hole 4A may be rotatably fitted into and held by a shaft portion 20 formed in the casing of the motor 19 for rotating the disk.

Further, one end 21A of a link arm 21 is rotatably connected to the tip 14B of the link lever 14 via a pivot 22, and a signal detection pickup 23 constituting an optical system is mounted on the tip 21B of the lever 21. It is supported. The objective lens of the pickup 23 faces the recording track on the lower surface of the disk 18. and,
A guide sliding contact portion 25 is formed on the outer periphery of the pick-up 23 to be brought into contact with a guide plate 24 .
The guide plate 24 is for guiding the pickup 23 so that it moves in the direction of the arrow X in FIG. It is preferable that the sliding contact portion 25 is constructed so that the sliding portion 25 and the guide plate 24 can smoothly slide by using a sliding means such as a roller or a bearing. For example, as shown in FIG. 5, guide strips 24A and 24B are provided on the guide surface of the guide plate 24 that contacts the sliding contact section 25, and the tip 21B side of the link arm 21 that contacts these strips 24A and 24B. If rollers 25A and 25B are provided in the guide plate 24, the pick-up 23 can smoothly reciprocate along the guide plate 24. Note that there is a fourth link between the link lever 14 and the link arm 21.
As shown in the figure, a tension spring 26 is stretched across the link arm 21 and biased so that the tip 21B side of the link arm 21 is always in contact with the guide plate 24.

In the above configuration, when the drive gear 17 is rotated by the motor 16, the passive gear 15 is rotated, and the link lever 14 is rotated around its rotation center O. That is, when the link lever 14 is rotated, the center P of the pick-up 23 on the link arm 21 moves on a trajectory X regulated by the guide plate 24, thereby enabling signal reading and tracking of the disc player. becomes. In this case, the guide plate 24 needs to be adjusted in advance so that the pick-up 23 is placed on the above-mentioned trajectory X. This can be done by using an adjustment jig (not shown) for the guide plate 24 centered around the center O of the link lever 14, or by adjusting the guide plate 24 by setting the pick-up 23 at each point on the outer circumference and inner circumference. generally easy to adjust. Note that the link lever 14, link arm 21, and guide plate 2 shown in FIG.
In the pick-up feeding device according to No. 4, it is necessary that the rotation center of the link lever 14 coincides with the rotation center of the disk.
It may be placed at any point as long as it is within the position where it contacts accurately.

In addition, FIG. 6 shows how to make the angle formed by the three spots always constant with respect to the tracking movement line when the pick-up 23 is moved along a linear guide such as the guide plate 24. An example of the configuration is shown.

That is, as shown in the same figure, pick up 2
Projecting arms 27 and 28 are provided protruding from 3, and each of these arms 2
Rollers 29 and 30 are rotatably supported at the ends of the rollers 7 and 28, and these rollers 29 and 30 are supported on the guide plate 24.
The three spots 23A, 23B, 23C are kept at right angles to the above-mentioned trajectory X.

As described above, in the present invention, accurate tracking is possible with a single simple guide for driving the pickup. Further, the pick-up feeding device can be constructed with two simple links such as the link arm and the link lever. Moreover, these link arms and link levers can be configured within the area of the disk, and the drive link shaft and drive motor can be installed at fairly arbitrary positions, making it possible to downsize the disk player and simplify its structure.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an outline of a video disc reproducing optical system, and FIG. 2 is a schematic plan view illustrating a three-spot method for detecting whether tracking is correct or incorrect. Third
The figure is a plan view schematically showing a conventional linear tracking mechanism, where A shows a linear drive system and B shows a rotary drive system. FIGS. 4 and 5 are views showing an embodiment of the present invention, with FIG. 4 being a schematic plan view and FIG. 5 being a front view. Furthermore, the sixth
The figure is a schematic plan view showing a modified example of the pickup portion. 14...Link lever, 21...Link arm, 23...Pickup, 24...Guide plate,
25... Guide sliding contact part.

Claims (1)

[Claims for Utility Model Registration] A link lever having a fulcrum at one end, one end of which is pivotally connected to the free end of the link lever, and a pick-up for reading out information signals recorded on a disk at the other end. a link arm provided with a guide sliding contact portion; a guide plate on which the guide sliding contact portion is guided in sliding contact; and a biasing means for urging the guide sliding contact portion in a direction to contact the guide plate. and a driving means for rotationally driving the link lever, and by rotating the link lever with the driving means, the guide sliding contact portion is reciprocated along the guide plate, and the pick-up is rotated. A pick-up feeding device for a disk player, which moves the disk in a radial direction.