JPS599097B2 - Pickup device for high-density recording disk playback - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pickup device for reproducing high-density recording discs, in which a plurality of frame-shaped elastic bodies are used to abut and lock on a pickup arm and urge a needle in the direction of contact with the disc. The elastic body is formed such that its frame surface is in a plane orthogonal to the axial direction of the pickup arm, and one end of each of the elastic bodies is
By configuring the pickup arm to be held directly, the spring constant of the elastic body can be set independently in the three axial directions of the pickup arm, including not only the vertical and horizontal directions, but also the front and rear directions, and furthermore, the spring constant of the elastic body can be set independently. An object of the present invention is to provide a pickup device for high-density recording disk playback that can obtain tracking and tracing characteristics.

Conventionally, various types of pickup devices have been known for use in devices that play back high-density recording disks (hereinafter referred to as video disks). A capacitance-type pickup N-up device has a configuration in which the detection element fixed to the tip of a pickup arm is brought into elastic contact with the disk surface by an elastic body fixed to the pickup arm.

FIG. 1 shows a schematic side view of an example of the conventional pickup device.

In Fig. 1, reference numeral 1 denotes a piezoelectric pickup device, in which a piezoelectric element 3 fixed to the lower surface of the tip of a pickup arm 2 is brought into contact with a groove of a disk 4, and picks up recorded signals as the disk 4 rotates. It is configured to do this. However, in this pickup device 1, a ring damper 6 having a toric surface is disposed between the outer circumferential surface of the body of the pickup arm 2 and the fixed wall 5 in the same plane as the axial direction of the pickup arm 2. Since the damper 6 urges the piezoelectric element 3 in the direction of contacting the disk 4, it is difficult to assemble the pickup arm 2 by aligning the axis of the pickup arm 2 with the annular surface of the ring damper 6, and when adjusting the stylus pressure. Since the ring damper 6 is subjected to complex loads not only in the vertical direction but also in the horizontal direction, the direction of the line of action of the ring damper 6 with respect to the pickup arm 2 is deviated diagonally, resulting in needle skipping. It had the disadvantage of being easy to use.

In addition, the spring constants of the ring damper 6 in the vertical and horizontal directions are determined taking into account design conditions such as disk surface vibration, eccentricity, and feed error of the pickup arm 2. When the width of the damper 6 is made smaller than the thickness in the radial direction, the ring damper 6 tends to buckle within its annular surface, which has the disadvantage that needle skipping becomes even more likely to occur.

Furthermore, when the ring damper 6 is fixed to the pick-up arm 2 by adhesive, it is difficult to uniformly bond the bonding area to each pick-up device 1 with high precision, and the bonding area may vary depending on the quality of this bonding work. ring damper 6
Since the spring constant of the spring is greatly affected, the spring constant cannot be accurately obtained as designed.

The present invention eliminates the above-mentioned drawbacks, and an embodiment thereof will be described below with reference to the drawings. FIGS. 2A and 2B respectively show a longitudinal sectional side view and a perspective view of essential parts of an embodiment of a pickup device for high-density recording disk reproduction of the present invention. Figure 2A
, B, 11 is, for example, a capacitive pickup device for reproducing a high-density recording disk according to the present invention, and a video disk 12 (for example, a diameter of 3001111 Thickness 1.
It has a housing 13 that is movably held, for example, about 2 centimeters above a disc made of vinyl chloride with a diameter of 5 to 2.0 nm. The upper surface of the video disk 12 is guided radially toward its center of rotation.

Inside the housing 13, an electromagnetically driven arm stretcher 14 for jitter correction and a cavity resonator (not shown) are arranged. It is detachably attached to a predetermined position via the upper surface opening 13a. The arm stretcher 14 has a bracket 1 provided inside the housing 13 so as to be slidable within a predetermined area.
6, and this bracket opening 6 is biased to the left in the figure by a spring 17.

A permanent magnet 18 is fixed to a mounting member 14b attached to the shaft 14a of the arm stretcher 14, and its magnetic force causes the pick-up arm 19 of the pickup cartridge 15 to be attached to the shaft 14a of the arm stretcher 14.
mechanically coupled to

Reference numeral 20 denotes the center conductor of the cavity resonator, which is electrically connected to the needle 21 when the pick-up cartridge 15 is installed in a predetermined position.

The pick-up cartridge 15 has a rectangular hollow cartridge case 22 made of plastic material, for example, with an open bottom and one side thereof.
4, 25, etc. are arranged at predetermined positions, respectively.

The lever 23 has a lever main body 23a having a flat plate shape with a long axis, and a bending portion 23b formed by bending the end portion of the lever main body 23a at a substantially right angle, and the base of the bending portion 23b is inserted through the lever main body 23a. Cartridge housing 22 by spring pin 26
It is mounted so that it can be rotated within a predetermined range in the clockwise and counterclockwise directions in FIG. 2A.

Reference numeral 27 denotes a spring, which includes a stud 28 planted on the inner wall of the upper surface of the cartridge housing 22 and one leg 29 of a pair of legs 29 and 30 formed by bifurcating the lower end of the bent portion 23b. The lever 23 is connected to the pin 2.
6 is energized clockwise in FIG. 2A in the center.

The pick-up arm 19 is elastically fixed at both ends to the lever 23 via dampers 24 and 25,
The needle 21 planted on the lower surface of the tip is electrically connected to the center conductor 20 of the cavity resonator via a band-shaped conducting piece 31 made of, for example, gold. Reference numeral 32 denotes a disk-shaped stopper member fixed to the distal end of the pick-up arm 19, and the stopper member 32 is connected to a wire made of iron, for example, via a piano wire 33 that is inserted between the pair of legs 29 and 30 of the bent portion 23b. Disc body 34
is fixed.

The damper 24 is formed in the shape of a rectangular frame from an elastic material such as butyl rubber with high viscoelasticity, and its frame surface is orthogonal to the axial direction of the pick-up arm 19, and the damper 24 is connected to the lower surface of the tip of the lever main body 23a of the lever 23 and the pick-up arm. Arm 19
It is interposed between the tip of the

This dasopa 24 is generally called a rigid frame structure, and has frame parts 24a, 24b, 24c, which are integrally formed in a rectangular shape.
24d has unique spring characteristics depending on the size and shape of the lever body 24d, one frame portion 24a is fixed to the lower surface of the lever main body 23a by adhesive, and the other frame portion 24 facing the frame portion 24a
b is elastically held integrally by the remaining pair of frame portions 24c and 24d in the up-down, left-right, and front-back directions. Therefore, the pick-up arm 19, which is fixed by adhesive to the recess 24h formed approximately in the middle of the frame portion 24b, is held elastically in the three axial directions. The damper 25 is formed into a triangular frame shape from an elastic material such as butyl rubber with high viscoelasticity, and its frame surface is orthogonal to the axial direction of the pick-up arm 19, and is substantially in contact with the lower surface of the end of the lever main body 23a of the lever 23. It is interposed between the pick-up arm 19 and the substantially distal end thereof. This damper 25 is generally called a truss structure,
Frame portions 25a, 25 integrally formed in a triangular shape with each other
b, 25c have unique spring characteristics depending on the size and shape, and one frame portion 25a is bonded to the lever main body 23a.
The pick-up arm 19 is fixed to the lower surface of the frame parts 25b and 25c, and the pick-up arm 19 is inserted through a through hole 25h formed at the top of the frame parts 25b and 25c, and the inserted part is fixed by adhesive.
25c, it is held elastically particularly in the front-rear direction. Since the spring force of the damper 25 in the vertical and horizontal directions is large, vibrations in the vertical and horizontal directions of the pick-up arm 19 are effectively damped at its end portion. Note that the needle pressure of the needle 21 is appropriately set to a desired value by making the initial displacement amount of the damper 24 variable.

Reference numeral 35 denotes a cover that is provided on the upper wall of the housing 13 of the pick-up device 11 so as to be able to be opened and closed about a hinge portion 36, and an adjustment screw 37 is disposed at the tip of the cover at a suitable position so that the screw length can be variably adjusted from the outside. ing.

When the pickup cartridge 15 is installed in the pickup device housing 13 and the cover 35 is closed, the adjustment screw 37 is inserted through the through hole 22a formed in the upper wall of the cartridge housing 22, and is inserted into the lever main body of the lever 23. 23a is pushed downward to move the lever 23 downward by a predetermined length. 3
A slide knob 8 is provided on the upper wall of the housing 13 of the pickup device 11 so as to be slidable over a predetermined range, and locks the closed cover 36 so that it cannot be opened.

Next, the operation of the above-mentioned component device will be explained with reference to FIGS. 3A to 3C.

FIGS. 3A to 3C are diagrams for explaining the deformed state of the damper 24 used in the above embodiment. The damper 24 is shown in Fig. 3A-
When subjected to forces in the directions of the arrows X, Y, and Z, as shown in C, the frame body is deformed into shapes unique to the frame structure, such as compression, tension, and deflection, but all of these deformations occur due to the axis of the pick up arm 19. This is done within a frame plane that is perpendicular to the direction.

Furthermore, the damper 24 deforms symmetrically in response to compression and tension deformations, and the direction of biasing the needle 21 is always perpendicular to the surface of the video disk 12. Unlike the conventional pickup device 1 which is configured to be biased by a ring damper 6 having a circularly fractured surface, the biasing direction of the ring damper 6 does not shift diagonally and cause needle skipping. Also, the damper 24 is the third
As shown in the figure, the frame portion 24b facing the frame portion 24a is elastically held by the pair of frame portions 24c and 24d, so only the frame portion 24b is deformed by the force in the direction of the arrow Z. The damper 24 will not be excessively deformed and distorted, and the damper 24 will always smoothly return to its original state when the above-mentioned force is released. Further, the damper 24 is also deformed in the axial direction of the pick-up arm 19 (not shown), but each frame portion 24b, 24c, 24d is
The spring constant for this elastic deformation in the axial direction is determined by the size and shape of each frame portion 24a to 24d and each frame in the axial direction of the pick-up arm 19. Since the spring constants in the up-down, left-right, and front-back (axial) directions can be determined independently of the thickness of the sections 24a to 24d, the pick-up arm 2 can be used as the ring damper 6 of the conventional pick-up device 1. There is no drawback that the tracing and tracking performance deteriorates because the spring constant in the axial direction cannot be selected independently of the spring constants in the vertical and horizontal directions, which impedes jitter correction.

Since the damper 24 is made of, for example, butyl rubber, which is a viscoelastic material, the needle 21 can be made to follow the signal groove faithfully by the vertical, horizontal, and front-back movement of the pick-up arm 19, and the machine It is possible to prevent a sudden drop in impedance at the resonance point, and furthermore, by setting the elastic coefficient of the damper 24 appropriately, the resonance magnification at the resonance point can be easily adjusted to about 1.3. It is possible to reliably prevent the occurrence of king error, tracing error, etc.

Here, when adjusting the stylus pressure of the needle 21, the needle 21 is displaced by a predetermined amount in the vertical direction by rotating the adjustment screw 37 in the forward and reverse directions and adjusting the screwing amount. The contact force of the needle 21 may be variably adjusted as appropriate.

This stylus pressure is substantially determined by the elasticity of the damper 24 according to its deformation. Note that, for example, the damper 24 is set to 0.1/1.
．． If a spring constant of 6 [Gr/1&m] is used, the pitch of the adjustment screw 37 should be set to 0.5 [Gr/R/R], for example.
ev] and its rotation range is divided into 20 steps (1 step is 18 degrees) to increase the adjustment sensitivity of the stylus force to 3.
125 [η/step], and therefore the stylus pressure can be adjusted with extremely high precision. In this way, the amount of deformation of the dampers 24 and 25 can be adjusted with high sensitivity, so even if the spring constant is increased, the stylus pressure can be adjusted extremely reliably, and the resonance frequency of the dampers 24 and 25 and the The selection range of DYNAMITSU CLEAN can be expanded satisfactorily. Further, in this embodiment, the distal end of the pickup arm 19 is held by a damper 25 having a truss structure that has elasticity almost only in the axial direction of the pick-up arm 19, and the distal end is held by the piano wire 33. Since the damper 25 is connected to the shaft opening 4a of the arm stretcher 14 through a Therefore, secondary resonance between the piano wire 33 and the pickup arm 19 can be reliably prevented, and the jitter correction effect described above can be even more excellent.

Furthermore, since the bonding area of both dampers 24 and 25 to the lever 23 is large, the mounting position of the dampers 24 and 25 can be accurately determined with respect to the lever 23, and therefore the pickup arm 19 can be accurately opposed to the lever 23. can be placed.

Next, other embodiments of the device of the present invention will be described.

4 and 5 respectively show perspective views of other embodiments of the essential parts of the pickup cartridge of the pickup device for high-density signal recording disc reproduction according to the present invention. In FIG. 4, the same components as those in FIG. 2B are designated by the same reference numerals, and their explanations will be omitted. In the embodiment shown in FIG. 4, the pick-up cartridge main part 41 has a damper 42 having substantially the same shape as the damper 24 having the frame structure, which is disposed at a substantially intermediate portion in the longitudinal direction of the lever main body 23a of the lever 23. A substantially middle portion of the arm 19 is configured to be elastically supported.

Therefore, the vibration of the pickup arm 19 itself can be effectively prevented, thereby effectively suppressing a sudden increase in the mechanical impedance at the resonance point of the pickup arm. Therefore, by constructing the damper 42 from, for example, butyl rubber, which has a smaller spring constant and better damping properties than the damper 24, tracking and tracing performance can be favorably improved over a wide range of frequencies. 43 is a stylus pressure adjustment member, which is located at the L of the lever 15.
The Z-bar is screwed into the proper position of the main body 22, and its upper end abuts against the inner wall of the top surface of the pickup device housing 13, so that the rotation limit position of the lever 23 is regulated according to the screwing amount. .

In FIG. 5, the same components as those in FIG. 4 are given the same reference numerals, and their explanations will be omitted.

In the embodiment shown in FIG. 5, the pick-up cartridge main part 44 has a cantilever 47 held at the tip of a pick-up arm 45 via a tubular rubber damper 46, and a cantilever 47 is held on the bottom surface of the tip of the cantilever 47. A needle 21 is planted.

Therefore, the pick-up arm 45 and the rubber damper 4
The mechanical impedance of the needle 21 increases up to the resonance frequency determined by the cantilever 47 and the rubber damper 46.
Since the impedance is reduced, the needle 21 can better follow up to high-frequency vibrations, and therefore has excellent wear resistance. Furthermore, the main part 44 of the pick-up cartridge having the above-mentioned configuration is
Since the frame-like damper 42 and the tubular rubber damper 46 are used to connect the pick-up arm 45 and the cantilever 47, not only can the needle 21 be accurately positioned in the front-rear direction, but also the needle pressure can always be accurate. In addition, the tracking and tracing characteristics of the pick-up arm 45 and the cantilever 47 are improved against surface runout and eccentricity of the disk in the low frequency range where the effect of the frame-shaped damper 42 is difficult to appear. It has the effect of improving the 6A and 6B show front views of other embodiments of the damper, respectively. In FIG. 6A, the dasopa 245 is the damper 245
A pair of frame portions 24'C have a shape in which the frame portion 24a is omitted.
, 24'd in the lever 23, the lever 2
A frame body structure is formed via 3, and the pick-up arm 19 is elastically held on the lever 23 by a predetermined spring like when the damper 24 is used. In Figure 6B, damper 25
' has a shape in which the frame part 25a of the damper 25 is omitted, and by embedding the pair of frame parts 25b and 25'c in the lever 23, a frame structure is formed via the lever 23, and the pickup arm 19 is Similarly to when the damper 25 is used, it is elastically held on the lever 23 by a predetermined spring.

In each of the above embodiments, the shape of the damper used is not limited to a square or triangular shape, but may also be a circular ring, an elliptical ring, a semicircular ring, a semielliptical ring, or a U-shape or a horizontal U-shape. It may be in the shape of an inverted U-shape, or the like, as long as it can be attached to the lever 23 with its frame surface orthogonal to the axial direction of the pick-up arm 19. Note that the frame body in this specification refers to a member integrally formed with a frame portion in a predetermined shape that defines a specific plane portion within one plane, and the frame surface refers to the above-mentioned frame body. It means a plane.

As described above, the pick-up device for high-density recording disc playback according to the present invention supports the needle at the rotating tip of the pick-up arm, which is provided in the pick-up device housing so as to be rotatable within a predetermined range, and is supported by an elastic body. In a pick-up device that elastically brings the needle into contact with a high-density recording disk via a pick-up arm to detect and reproduce the recording alert signal, the elastic body is moved in a direction perpendicular to the axial direction of the pick-up arm. It is composed of a plurality of frame-like elastic members each having a frame surface, and the pick-up arm is directly held by one end of each of the frame-like elastic members.
Not only can the stylus pressure be applied by the elastic force of the elastic member itself, but the pick-up arm can be elastically held not only in the vertical and horizontal directions, but also in the front-back direction, and can be Since the spring constants can be set to predetermined values independently of each other, and multiple frame-like elastic members are provided, it is possible not only to accurately set the static stylus pressure to the desired value, but also to move the pick-up arm. It has features such as extremely good physical properties, ie, tracking and tracing properties.

[Brief explanation of drawings]

Figure 1 is a schematic side view of an example of a conventional pickup device;
FIGS. 2A and 2B are a longitudinal sectional side view and a perspective view of essential parts of an embodiment of a pickup device for high-density recording disk reproduction of the present invention, respectively, and FIGS. 3A to 3C are elastic bodies used in the pickup device described above, respectively. FIGS. 4 and 5 are perspective views of other embodiments of the main parts of the pick-up cartridge of the pick-up device for high-density recording disc playback, and FIGS. 6A and 6B are diagrams for explaining the deformed state of the FIG. 7 is a front view of another embodiment of each elastic body. 11... Capacitive pickup device, 12...
...Video disk, 13...Pick-up device housing, 15...Pick-up cartridge, 19...Pick-up arm, 21...
...Needles, 24, 24', 25, 25', 42...
・Damper, 24a to 24d, 25a to 25c, 24'b
~24″D, 25′B, 255c... Frame.

Claims (1)

[Claims] 1. A needle is supported at the rotating tip of a pickup arm that is provided in the housing of the pickup device so as to be rotatable within a predetermined range of angles, and the needle is elastically brought into contact with the high-density recording disk via the pickup arm using an elastic body. In a pickup device that detects and reproduces a recorded information signal in contact with the pickup arm, the elastic body is constituted by a plurality of frame-shaped elastic members having frame surfaces in a direction perpendicular to the axial direction of the pickup arm, and the frame A pickup device for reproducing a high-density recording disk, characterized in that the pickup arm is directly held by one end of each of body-shaped elastic members.