JPS6160499B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pickup device particularly suitable for a capacitive video disc player.

In a capacitive video disk, information such as a video signal is recorded as an encoded geometric pattern made of an electrically conductive film in grooves arranged spirally on the surface of the disk. On the other hand, a pick-up device is equipped with a playback needle that includes an electrode that forms a capacitor with a conductive film recorded on the disk surface while sliding relative to the disk surface.
This regeneration needle is attached to the tip of a cantilever that can be corrected in three axis directions: Recorded information such as video signals is picked up from the disk as the capacity changes. Jitter correction and stylus pressure correction are performed on the regenerated stylus via a cantilever in order to maintain accurate relative positional relationship with the disk depending on rotational unevenness, surface runout, etc. When the correction force applied to the cantilever is vectorially resolved, it is desirable that the cantilever ideally extend parallel to the disk surface. However, since conventional cantilevers are made from conductive aluminum pipes, when they are brought close to the disk, stray capacitance is generated between the cantilever and the disk, which may cause disturbance noise to the electrodes. There is. Therefore, in conventional pick-up devices, the regeneration needle is attached to the tip of an aluminum pipe cantilever via a holding plate made of hard synthetic resin such as nylon, and this cantilever is attached to a disk like the cantilever of a general audio cartridge. It is oriented obliquely to the plane. According to this, especially during jitter correction, the correction force applied to the cantilever is decomposed into a horizontal vector component and a vertical vector component, and the vertical vector component causes the cantilever to slightly crank around the fulcrum at its rear end. Become. As a result, the contact point of the playback needle with respect to the disk was not constant, and there were cases in which it was not possible to accurately pick up video signals and the like.

The present invention was made in view of the above-mentioned drawbacks of the conventional devices, and its purpose is to provide a pickup device that can accurately pick up video signals by keeping the contact point of the playback needle with respect to the disk constant at all times. It's about doing.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, this pick-up device includes a cantilever 1. As shown in FIGS. This cantilever 1 includes a first portion 3 extending parallel to the surface of a video disk 2, and a second portion 4 rising approximately at right angles from the rear end of the first portion 3.
In this case, the first portion 3 and the second portion 4 are integrally made of a synthetic resin material such as hard nylon or an electrically nonconductive material such as ceramic. ing. In addition, when making it from a synthetic resin material, it is preferable to use glass fiber as a reinforcing material. A regenerating needle 5 is attached to the tip of the first portion 3. Although not shown in detail in this figure, the playback needle 5 consists of a diamond chip having a sliding surface against the video disk 2, and an electrode formed on the front surface of the chip by vapor deposition or the like. This electrode forms a capacitor with a conductor film provided in a geometric pattern on the side of the disk 2, and a video signal is picked up from the disk 2 by changing the capacitance distributed between them. This video signal is led to an output terminal 8 provided in the housing 7 via a lead member 6 made of a conductor strip, and is inputted from there to a predetermined signal processing circuit. On the other hand, the second
A cylindrical magnet 9 having an axis parallel to the first portion 3 is fixed to the upper end of the portion.
This magnet 9 has X magnets spaced apart from each other by approximately 90 degrees in a virtual plane orthogonal to its axis.
A rubber cover 11 having four rod-shaped rubber dampers 10 oriented in a letter shape is attached. Therefore, as shown in FIG. 3, by locking the other end of each damper 10 to the housing 7, the cantilever 1 is elastically supported within the housing 7 by each of these dampers 10. .
Further, this pickup device has correction means for correcting the cantilever 1 in three axial directions in relation to the magnet 9. That is, this correction means includes a first jitter correction means disposed coaxially behind the magnet 9.
four second electromagnets 13 for tracking correction arranged in pairs on both sides of magnet 9, and a third electromagnet 14 for stylus force adjustment arranged above magnet 9.
It consists of. Therefore, by controlling the excitation current for each electromagnet 12, 13, and 14 by a control device (not shown), the cantilever 1 is moved to It is controlled in three axial directions: the axial direction, the Y-axis direction, and the Z-axis direction.

According to this pick-up device, the cantilever 1 is composed of a first portion 3 extending horizontally and a second portion 4 extending vertically from the rear end of the first portion 3. When correcting jitter by exciting the electromagnet 12 and driving the cantilever 1 in the Therefore, the regeneration needle 5 attached to its tip slides back and forth on the disk 2 in the X-axis direction, that is, along the rotational direction of the disk 2, without shifting its contact point. On the other hand, when the third electromagnet 14 is excited to correct the stylus pressure, the force applied to the reproduction stylus 5 via the magnet 9, the second part 4, and the first part 3 is almost only a vertical vector component. As a result, disk 2 of regenerated needle 5
There is little risk that the contact point will shift. Furthermore, since the cantilever 1 is made of an electrically nonconductive material such as synthetic resin or ceramic, even if it is placed close to the disk 2, stray capacitance that becomes disturbance noise will be distributed between them. There's little to do. Regarding the damper that elastically supports the cantilever, when supporting the cantilever at its rear end, the cantilever should be supported at the center of the rubber membrane, or as shown in FIG. 3 of this invention, From the viewpoint of uniform support, it is most preferable to support the cantilever with rod-shaped dampers oriented in each direction at 90-degree intervals, but when this is applied to a conventional device, the fulcrum of the cantilever is It will be set at a higher position. Therefore, if you try to make the cantilever longer, there is a risk of resonance, so conventionally the cantilever is supported by a pair of dampers extending horizontally, even at the expense of equal support. That's what I do. In contrast, according to the present invention, four rod-shaped dampers oriented at 90 degree intervals can be used without being subject to the above-mentioned special restrictions by simply lengthening the second portion 4 of the cantilever 1. 10 can ideally support the cantilever 1.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing a pick-up device according to the present invention, FIG. 2 is a side vertical sectional view thereof,
FIG. 3 is a sectional view taken along the line -- in FIG. 2. In the figure, 1 is a cantilever, 2 is a video disk, 3 is a first part, 4 is a second part, 5 is a regeneration needle, 6 is a lead member, 7 is a housing, 9 is a magnet, 10 is a damper, 12, 13 and 14 are electromagnets.

Claims (1)

[Scope of Claims] 1. A capacitor is formed between a conductive film representing a video signal, etc. arranged in a predetermined geometric pattern on a video disk, and the video signal is expressed as a change in the capacitance. a regeneration needle including an electrode for regenerating the regeneration needle, a cantilever supporting the regeneration needle, a support means for elastically holding the cantilever with a magnet portion at its rear end as a fulcrum, and a support means magnetically coupled to the magnet. and a correction means consisting of a plurality of electromagnets configured to correct the regeneration needle in three axial directions via the cantilever using its attractive force or repulsion force, the cantilever a first portion supporting the video disc and extending parallel to the surface of the video disk; and a second portion rising substantially perpendicularly from the rear of the first portion and connected to the magnet at its rising end. A pickup device for a video disc player characterized by being formed into a substantially L-shape. 2. A pickup device for a video disc player according to claim 1, wherein the cantilever is integrally made of a hard electrically nonconductive material with a high dielectric constant. 3. In claim 1, the magnet comprises a columnar body having an axis parallel to the first portion of the cantilever, and the support means comprises:
A pick-up device for a video disk player, characterized in that it comprises four rod-shaped rubber dampers extending radially at intervals of 90 degrees from each other with the magnet as the center in a virtual vertical plane perpendicular to the axis of the magnet.