JPS5824297Y2 - Signal pickup device for rotating recording media - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a signal pickup device for detecting and reproducing information signals from a rotating recording medium, in which a cartridge having a cantilever supported swingably is mounted in a cartridge holder having a pivot point. In addition, by setting the rotation fulcrum at a predetermined position, the cartridge to be replaced can have a very simple structure without providing a rotation mechanism, and the cartridge can be easily attached and detached. An object of the present invention is to provide a signal pickup device for a rotating recording medium that is configured so that a reproducing needle (scanner) can be attached to and separated from the rotating recording medium without damaging the reproducing needle.

In general, in a device that reproduces information signals by relatively scanning the information track of a rotating recording disk, where the information signal is recorded as a change in geometric shape, with a reproduction needle, the reproduction needle has a limited lifespan due to wear. , car including regenerated needle) I
The J-judge is replaceable.

Conventional signal pickup devices have a structure in which the cartridge to be replaced is provided with a rotation mechanism, which has the disadvantage that the structure of the cartridge itself is complicated and the installation and removal operations when replacing the car IJ are troublesome. there were.

Since multiple IJs are prepared for one playback device, it is desirable that they be as inexpensive as possible.

Further, as a conventional signal pickup device, there is one having the configuration shown in FIG.

In this device, a cantilever 2 having a regenerating needle 1 fixed at its tip is connected at its base side to a movable shaft 4aK of an arm stretcher 4 via a damper 3.

The housing 5 housing the arm stretcher 4 rotates around a shaft 6 at one end to move the playback needle 1 up and down, bringing it into contact with or away from a rotating recording medium (video disc) 7.

Here, since the shaft 6 is located on the side opposite to the regenerating needle side with respect to the swinging fulcrum of the cantilever 2, the following inconvenience occurs.

In FIG. 2, point O represents the center of rotation of the housing 50 ← axis 6), point A represents the center of swing of the cantilever 2 (damper 3),
K■ and A1 represent the housing 5 and the cantilever 2, respectively.

When the housing 5 is rotated counterclockwise and the playback stylus 1 has applied vinegar to the video disc 7 (the stylus pressure is zero), the cantilever 1 and the housing 5 are in the state shown by the solid lines, and the cantilever 1 is in the position shown by the solid line. It is tilted by an angle α with respect to the

When the housing 5 is further rotated counterclockwise to the position shown in FIG. 1 in order to apply stylus pressure, the damper 3 is deformed and moved to point A.
is displaced to point A', and the angle α becomes small.

Looking at the operation of the playback needle 1 at this time, when the stylus pressure is zero, the corner of the electrode 1b on the back side of the sliding surface 1a of the playback needle 1 is close to the disc, as shown in an enlarged view in FIG. Contact with I.

Since stylus pressure is applied to the regenerated needle 1 with only the corners of the electrode 1b in contact and the other parts floating, stress concentrates on the corners of the electrode, accelerating the wear of this part.

Since this phenomenon occurs each time a performance starts and stops, it has the disadvantage of shortening the life of the playback needle 1.

The present invention eliminates the above-mentioned drawbacks, and one embodiment thereof will be described below with reference to the drawings.

4 and 5 are longitudinal sectional front views of one embodiment of the signal pickup device for a rotating recording medium according to the present invention during cartridge replacement and playback, respectively, and FIG. 6 shows the single cartridge in FIG. 4. Exploded perspective view, Figure 1 is similar to Figures 4 and 5.
FIG. 2 is a schematic perspective view of the tracking control and jitter compensation mechanism incorporated in the device shown in the figure.

In FIGS. 4 and 5, a signal pickup device housing 10 is provided at a height slightly apart from a rotating recording medium (video disc) 121 placed on a turntable 11, and a cartridge 20 (described later) is set as shown in FIG. 5, and is transported in the radial direction at a predetermined speed in synchronization with the rotation of the turntable 11.

At this time, a reproducing needle 13 (same configuration as the reproducing needle shown in FIG. 3) is attached to the disk 12 and relatively scans this information track, picking up and reproducing the information signal as a change in capacitance.

The device housing 10 includes a rotating lid 15 that rotates around a shaft 14.
The rotary lid 15 rotates between an open position for replacing the cartridge as shown in FIG. 4, and a closed position for covering the opening 1a and making playback possible.

Reference numeral 16 denotes a cartridge holder, which is rotatably supported on the shaft 14.

The cartridge holder 16 has a coil spring 1 which is inserted between the holder 16 and the rotary lid 15 by fitting into a pin 17 which is installed on the top surface and which is inserted through the rotary lid 15.
8 applies a rotational force in the counterclockwise direction, and the E washer 19 fitted on the pin 17 is in contact with the upper surface of the lid 15, that is, in a state where it is actively separated from the lid 15, and the rotation is made. The button is limited and rotates substantially integrally with the rotating lid 15.

Further, the holder 16 has a U-shape in plan view, and a guide groove 16a is formed on the inner surface of each arm portion, into which a cartridge base 21, which will be described later, is tightly fitted.

In addition, as shown in FIG. 4 and FIG. , and is disposed at a position offset toward the reproduction needle side with respect to the center of swing of the cantilever 25.

Thereby, as will be described later, it is possible to prevent excessive stress concentration from occurring at the rear corner of the reproducing needle 13 when starting and stopping the reproducing performance.

Further, by configuring the cartridge holder 16 to rotate, the cartridge 20 described later can be constructed without providing a rotation mechanism.

In the above configuration, the rotation center axis of the cartridge holder 16 and the rotation center axis of the rotation lid 15 are common, but they may be provided separately at different positions.

20 is a cartridge, and as shown in FIG. 6, a cantilever 25 is fixed to a cartridge base 21 via a pair of dampers 22 and 23, with a regenerating needle 13 fixed to the tip side and a permanent magnet piece 24 fixed to the base side. It is roughly structured to support the following.

The cantilever 25 and the pair of dampers 22 and 23
are a pair of side walls 21 formed near both ends of the base 21.
a and 21b.

As is clear from FIG. 7, the damper 22 that supports the tip end side of the cantilever 25 has a rectangular shape, and the cantilever support portion is arranged horizontally as indicated by arrow X, vertically as indicated by arrow Y, and in the vertical direction as indicated by arrow Z. Cantilever can be displaced in the axial direction.

Also, a damper 23 supporting the base side of the cantilever 25
has a triangular shape, and the cantilever support part is limited in displacement in the directions of arrows X and Y, but allows displacement in the direction of arrow Z and rotational displacement shown by arrows β and γ.

As a result, the cantilever 20 is moved around the support portion provided by the damper 23 with respect to the vertical axis and the horizontal axis, respectively, as shown by the arrows β.
and rotate in the r direction.

Further, a pair of side walls 21a and 2 of the cartridge base 21
In 1b, the portion facing the regeneration needle 13 is narrow.

The cartridge cover 26 has a pin 2 protruding inside thereof.
6a is fitted and coupled to the hole 21c in the narrow portion, and normally covers and protects the regenerating needle 13 to prevent damage to the regenerating needle 13 when handling the cartridge 20 alone.

Note that when the cartridge 20 is attached to the cartridge holder 16 as described later, the cover 26 is rotated 90 degrees counterclockwise in FIG. 6.

As a result, when the device is set to the playable state, the notch 26b of the cover 26 fits into the center conductor 30, which will be described later, and no inconvenience occurs.

Further, one end of a freely bendable metal ribbon 27 is connected to the electrode film of the regeneration needle 13, and the other end is fixed to the lower raw end side of the cartridge base 21.

Next, a description will be given of the cartridge exchange operation and the playable state setting operation in the apparatus configured as described above.

The IJ Tsuji 20 (indicated by the dotted chain line in FIG. 4) is at the stop position where the housing 10 is removed from the turntable 11, and the rotary lid 15 is opened and the cartridge holder is closed. 16 is in the rotational position shown in FIG. 4, by aligning both ends of the cartridge base 21 with the guide groove 15aK [and pushing it in the direction of the arrow ■ to the position where movement is restricted, as shown in FIG. will be installed on the

Note that since the cartridge 20 does not have a rotation mechanism, the above-mentioned mounting can be easily performed.

Similarly, the detachment operation for extracting the cartridge 20 from the cartridge holder 16 is easily performed.

Next, the rotating lid 15 is rotated counterclockwise about the shaft 14.

By this operation, the cartridge holder 16 is also moved to the shaft 1.
4 in the same direction, and the cartridge 20 is rotationally displaced together with the holder 16.

Rotate the rotating lid 15 to the position shown in FIG.
is screwed into the female screw 29, and the opening 10a is closed.

As a result, the cartridge 20 rotates somewhat clockwise against the coil spring 18, and the E washer 19 moves the rotating lid 15.
The metal ribbon 27 on the bottom surface of the tip of the cartridge base 21 is pressed against the tip of the center conductor 30 of the coaxial resonator in the housing 10, and the metal film of the regeneration needle 13 and the center conductor 30 are electrically connected. Connected securely.

Further, the reproduction needle 13 protrudes from the lower opening of the housing 10 and reaches a height position where it comes into contact with the video disc 12.

Note that by rotating the stylus pressure adjustment screw 31 provided on the housing 10, the center conductor 30 is bent and its tip is displaced in the vertical direction.

This causes the cartridge holder 16 to move toward the cartridge 2.
0 and rotates slightly around the shaft 14 independently of the rotary lid 15, the amount of deformation of the damper 22 changes, and the stylus pressure of the reproducing needle 1 during reproducing performance is adjusted to a predetermined value.

Here, since the adjustment screw 31 is provided in the unmovable housing 10, it is not subject to any adverse effects on needle pressure adjustment, and the needle pressure can be accurately adjusted and maintained.

In addition, by this operation, the stylus pressure adjustment screw is adjusted to the center conductor 30.
The stylus pressure may be adjusted by bending the needle upwardly.

Note that when starting and ending (stopping) the performance, the rod 32 is pulled in the direction of the arrow (■).

When the rod 32 is pulled, the single-shaped lever 33 rotates counterclockwise about the shaft 34, and its horizontal arm engages the lower surface of the IJ jig holder 16 and pushes it up.

As a result, the cartridge holder 16 and the cartridge 20 rotate clockwise about the shaft 14, the playback needle 13 rises and separates from the video disc 12, and the metal ribbon 27 separates from the center conductor 30, resulting in a non-playing state.

In this state, the dampers 22 and 23 are not deformed;
Since no force other than the weight of the cantilever 25 acts, there is no risk of permanent deformation of the dampers 22 and 23 made of viscoelastic rubber or the like.

Now, the operation of attaching and separating the reproduction needle 13 from the disk 12 during the above-mentioned needle raising and lowering operation will be explained with reference to FIGS. 8 and 9.

In FIG. 8, point 01 represents the center of rotation of cartridge 20 (shaft 14), and point A1 represents the swinging fulcrum of cantilever 25 (supported by damper 23).

Further, the point 01 is located on the reproduction needle side from the line l passing through the point A1 and perpendicular to the cantilever 25, and on the upper side of the cantilever 25, that is, on the opposite side of the disk 12 with respect to the cantilever 25.

When the playback needle 13 comes into contact with the disk 12 by the needle lowering operation (when the needle pressure is zero), the cantilever 25 and the playback needle 13 are at the position shown by the solid line, and the cantilever 25 is at an angle α1 with respect to the disk 12. It is sloping.

When the needle lowering operation further progresses and needle pressure is applied to the regenerating needle 13, since point 01 is placed at the above position, point A is displaced in a higher direction and moves to point A', and the regenerating needle 13 moves to the position shown by the broken line, the cantilever 25 is displaced as shown by the broken line, and the angle α1 becomes a dog.

Looking at the operation of the playback needle 13 at this time, when the needle pressure is zero, the playback needle 13 has its sliding surface 13a on the upper front side in the scanning direction, that is, on the introduction side of the disk, as shown in an enlarged view in FIG. Attached to 12.

The needle pressure reaction force against the regenerating needle 13 is applied from its introduction side,
The electrode 13b on the back side gradually comes into contact with the disk 12 as the stylus pressure is applied.

On the other hand, during the oblique ascending operation, the reproduction needle 13 moves away from the disk 12 from the electrode 13b side.

Thereby, there is no possibility that stress will be concentrated on the electrode 13a and this portion will be damaged when the regeneration needle 13 moves up and down.

Note that when the playback needle 13 is moved up and down by operating the needle pressure adjustment screw 31, it is attached to and separated from the disk 12 in the same manner as described above.

Next, the tracking control mechanism and jitter compensation mechanism provided in the above-mentioned configuration device will be explained with particular reference to FIG. 7.

The permanent magnet piece 24 has a rectangular parallelepiped shape and is magnetized with its side surfaces serving as north and south poles.

This permanent magnet piece 24 is fixed to the bottom surface of the car IJ holder 16 and is loosely fitted into a tracking control coil 35 wound in a rectangular shape.

Also, adjacent to both sides of this coil 350, jitter compensation coils 36 and 37 connected in series are fixed.

When a tracking control current is supplied to the coil 35, a torque is generated in the permanent magnet piece 24 about its vertical axis, and this torque causes the cantilever 25 to rotate β around the point supported by the damper 23, so that the reproduction needle 13 is perpendicular to the information track. Tracking control is performed by displacing the object in the direction shown in FIG.

Furthermore, when a jitter compensation current is applied to the coils 36 and 37, a force is generated in the permanent magnet piece 24 in its longitudinal direction,
This displacement force causes the cantilever 25 to displace in the direction of arrow Z, and the reproducing needle 13 to displace in the information track direction, thereby performing a jitter compensation operation.

However, the device of the present invention is applicable not only to a signal pickup device for a capacitive video disc playback device, but also to a signal pickup device for a device that plays back information signals by detecting geometric shape changes using piezoelectric elements, for example. The same applies.

As described above, the signal pickup device for a rotating recording medium according to the present invention includes a cartridge that supports a cantilever having a scanning element on its tip side so as to be swingable about its base side, without providing a rotation mechanism, Since the cartridge holder, into which the cartridge is installed and removed, is configured to be rotatable with respect to the main body of the device, the structure of multiple cartridges, which must be prepared for replacement, is simplified and the manufacturing cost is reduced. In addition, the rotational fulcrum of the cartridge holder is located closer to the tip of the cantilever than the swinging fulcrum of the cantilever, and on the opposite side of the cantilever from the rotating recording medium. Therefore, it is possible to prevent disadvantages such as deterioration of the reproduction signal and shortening of the life of the reproduction needle without damaging the back side corner of the reproduction needle, which plays an important role in signal reproduction during the movement of the needle up and down. It has excellent features.

[Brief explanation of the drawing]

FIG. 1 is a partially longitudinal front view of an example of a conventional signal pickup device, FIG. 2 is a diagram schematically showing the movement of the regeneration needle up and down in the device shown in FIG. 1, and FIG. 3 is the same as that shown in FIG. 1. FIGS. 4 and 5 are enlarged views showing the state in which the playback stylus is attached to the video disc in the device, and FIGS. 4 and 5 respectively show the state when the cartridge is replaced and 6 is an exploded perspective view showing the single cartridge in FIG. 4, and FIG. 7 is a tracking control and jitter compensation mechanism incorporated in the device shown in FIGS. 4 and 5. FIG. 8 is a diagram schematically showing the lifting and lowering movement of the regenerating needle in the device shown in FIGS. 4 and 5, and FIG. 9 is a schematic perspective view of the regenerating needle in the device shown in FIGS. FIG. 2 is an enlarged view showing the state when attached to a video disc. DESCRIPTION OF SYMBOLS 10... Signal pickup device housing, 12... Video disc, 13... Playback needle, 14... Shaft, 16...
...Cartridge holder, 18...Coil spring, 20
... Cartridge, 21 ... Cartridge base,
25... Cantilever 31... Needle pressure adjustment screw, 3
3...L-shaped lever.

Claims (1)

[Scope of utility model registration request] A cartridge is attached to a device that detects and reproduces an information signal by relatively scanning an information track of a rotating recording medium with a scanning element, and supports a cantilever having the scanning element on its tip side so as to be swingable around its base side. / is mounted on a cartridge holder that is provided in the main body of the device and rotates about a rotational fulcrum.
A signal pickup device for a rotating recording medium, which is removably provided, and the rotating fulcrum is located on the opposite side of the cantilever from the rotating recording medium and at a position closer to the tip of the cantilever than the swinging fulcrum of the cantilever. .