JPS6319970Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a video disc cartridge that is installed in a signal reproducing pickup of a needle-type video disc player such as a capacitive type.

There are two types of capacitive video disks: the RCA type, which has a groove on the disk surface to guide the stylus tip, and the VHD type, which does not have a guide groove.In both cases, the stylus has an electrode for capacitance detection. It has a membrane attached.

For example, a VHD format video disk
A video disk cartridge mounted in a player's pickup was constructed as shown in FIGS. 1 and 2.

To explain this simply, a holder 2 is fixed within an arm gauge 1 that moves in parallel in the radial direction of the disk, and a cartridge 3 is removably attached to this holder 2 and positioned by a click ball 4.

In the cartridge 3, the base of a straight cantilever 5 is rotatably supported by a shaft-shaped rubber damper 6 between both side plates (not shown).
The distal end portion of is also locked by a rubber damper 7.

A stylus 9 is attached to the tip of the cantilever 5 via a glass rod 8.
A fly lead 10 from which a signal is extracted is pulled out from this needle 9.

A magnet 11 is fixed to the rear end of the cantilever 5, and is fitted into a coil portion of an electromagnetic actuator 12 for tracking and jitter correction fixed to the holder 2, and is used for tracking in the direction indicated by arrow A in FIG. While correction and jitter correction in the direction shown by arrow B are performed, the tip of the needle 9 traces a predetermined track on a video disk (not shown) to reproduce the signal.

In such a conventional video disk cartridge, the height position of the fulcrum of the cantilever pivoted by the rubber damper 6 with respect to the needle tip (the needle is not shown) and the video disk surface (hereinafter simply referred to as "disc surface") are determined. ) will be explained with reference to FIG. 3.

As shown in FIG. 3A, when the height of the fulcrum P of the cantilever 5 from the tip of the needle, that is, from the disk surface 13 is high _H1 , the tip of the needle moves up and down by ±d due to vertical vibration due to deformation of the disk surface 13, etc. When moving, a jitter fluctuation of width δ ₁ occurs.

On the other hand, as shown in FIG. 3B, when the height of the fulcrum P of the cantilever 5 is low _H2 , even if the needle tip moves up and down by ±d as in the case described above,
The jitter fluctuation width becomes smaller as shown by δ ₂ .

Next, with reference to FIG. 4, the amount of floating force acting on the cantilever in the vertical direction due to dynamic friction between the disk surface and the needle will be explained.

As shown in FIG. 4A, when the fulcrum P of the cantilever 5 is at a high position _H1 , the dynamic friction force F between the disk surface 13 and the needle causes a relatively large floating force indicated by _f1 in the vertical direction of the cantilever 5. It acts on, but
If the position of _the fulcrum P is set low at H ₂ as shown in FIG.

It goes without saying that a smaller floating force is desirable because it allows a more stable damping system to be selected.

In this way, by lowering the fulcrum of the cantilever as much as possible and reducing its inclination with respect to the disk surface, less jitter correction for vertical vibration of the disk surface is required, and it is also easier to obtain a stable damping system. Therefore, it is desirable to lower the fulcrum P, but there is a problem that there is no space for the electromagnetic actuator shown in FIG. 1, and the fulcrum cannot be lowered much.

This idea was made to solve these problems by lowering the actual fulcrum of the cantilever and minimizing its inclination with respect to the disk surface while securing space for the electromagnetic actuator. purpose.

Therefore, the video disc cartridge according to this invention is composed of a base portion formed by bending a cantilever vertically into a substantially crank shape, and a needle attachment portion connected to the tip of the lower side via a leaf spring damper. By pivoting the upper side of the base to the cartridge case using a rubber damper, the inclination of the needle attachment part with respect to the disk surface can be minimized, and the rear end of the base can be inserted into the electromagnetic actuator without any problem. This is how it was done.

Hereinafter, an embodiment of this invention will be explained with reference to FIGS. 5 and 6. Parts similar to those in FIGS. 1 and 2 are denoted by the same reference numerals, and explanations of those parts will be omitted. .

The cantilever 15 in this embodiment is bent in a crank shape in the vertical direction, and its upper side 151
A is a base 151 that is pivotally supported between both side plates (not shown) of the cartridge via rubber dampers 6, 6, and a needle attachment portion 1 that is connected to the tip of the lower side 151b of this base 151 via a leaf spring damper 152 and extends.
53, and the needle attachment part 153 is attached to the arm gauge so that the inclination with respect to the disk surface 13 is the minimum necessary during use.

By configuring the cantilever 15 in this way, the fulcrum P of the base 151 can be made high so that the rear end can be fitted into the electromagnetic actuator 12 without any trouble, and the substantial fulcrum P' relative to the needle attachment part 153 can be made sufficiently high. Since the height can be set low and the inclination with respect to the disk surface 13 can be minimized, the fluctuation range of jitter and the floating force due to dynamic friction of the needle tip can be made extremely small.

In addition, since the leaf spring damper 152 is difficult to deform in both the width direction and the longitudinal direction, the effects of tracking correction and jitter correction by the electromagnetic actuator 12 are not reduced, and the disk surface 1
8 only in the vertical direction, it slightly bends around point P' as a fulcrum to absorb it, thereby reducing jitter fluctuations and the force acting in the direction in which the needle tip floats.

As explained above, according to the present invention, in a video disk cartridge, the substantial fulcrum of the cantilever is lowered to reduce the inclination with respect to the disk surface while securing space for the electromagnetic actuator for tracking and jitter servo. By minimizing this and absorbing the vertical movement due to the deflection of the leaf spring damper, it is possible to extremely minimize the jitter fluctuation range and the force acting in the direction in which the needle tip floats.

[Brief explanation of drawings]

FIG. 1 is a vertical cross-sectional view of a conventional video disc pickup, FIG. 2 is a perspective view of the cantilever part, and FIGS. Figures 4A and 4B are explanatory diagrams for explaining the relationship, and Figure 4A and B are explanatory diagrams for explaining the relationship between the height of the fulcrum of the cantilever and the floating force perpendicular to the cantilever generated by dynamic friction of the needle tip. FIG. 5 is a perspective view of essential parts showing an embodiment of this invention, and FIG. 6 is a side view thereof. 1...Arm gauge, 2...Holder, 3...Cartridge, 5...Cantilever (conventional), 6,
7...Rubber damper, 8...Glass rod, 9...
Needle, 10... Fly lead, 11... Magnet, 12
...Electromagnetic actuator, 13...Disk surface,
15... Cantilever (this invention), 151... Base, 152... Leaf spring damper, 153... Needle attachment part.

Claims (1)

[Claims for Utility Model Registration] A needle is held at the tip of a cantilever, the base of the cantilever is pivoted to a cartridge case via a rubber damper, and the rear end is fitted into an electromagnetic actuator for tracking and jitter servo. In the video disc cartridge, the cantilever has a base part which is bent in the vertical direction into a substantially crank shape and whose upper side part is pivoted to the cartridge case via a rubber damper, and a leaf spring at the tip of the lower part of the base part. 1. A cartridge for a video disc, characterized by comprising a needle attachment part connected via a damper and extending slightly inclined with respect to the disc surface.