JPS59892B2 - Method for manufacturing a capacitive disk-shaped recording medium playback needle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a capacitive disk-shaped recording medium reproducing needle, which is particularly capable of improving polishing efficiency, is suitable for mass production, and has the possibility of automation of polishing. The purpose is to provide a manufacturing method that can be improved.

The present applicant previously proposed in Japanese Patent Application No. 51-38809 a capacitive disk-shaped recording medium reproducing device that enables special reproduction operations such as still reproduction and high-speed reproduction.

In this device, the disk-shaped recording medium (hereinafter referred to as a video disk) is of a so-called grooveless type, and the applicant has proposed various playback needles that can be used for this. FIG. 1 shows a regeneration needle proposed by the present applicant in Japanese Patent Application No. 52-20065, and FIG. 2 shows the shape of the disk sliding surface of this regeneration needle.

In the completed regenerated needle 1 shown in FIG. 1, 2 is an electrode surface;
3, 3', 4, 4' are polished surfaces. The abrasive surfaces 3, 3' define the electrode edges 5, 5', respectively, and also define the contours 11, 11' of a portion of the disc abutment surface shape. another polishing surface 4,
4' defines the angle β of the leading edge 6 with respect to the disk sliding surface 10 and the contour lines 12, 12' of a part of the shape of the abutting surface.
The electrode sliding contact surface 13 has a thickness as shown in FIG. 2, is polished in the direction in which the contour lines 11 and 11' extend, and has a trapezoidal shape whose width becomes narrower as it moves away from the side surface of the needle base material. is formed. Reference numeral 14 denotes a center line extending in the disk relative scanning direction of the sliding contact surface 10, which in an ideal state is a straight line passing through the center of the electrode width a and the introduction side point 15.

This regenerated needle 1 has the following problems regarding its manufacturing process.

C. It is necessary to separately polish the four surfaces in addition to the electrode surface.

That is, since all of the above-mentioned four surfaces (3, 3', 4, 4') are flat, the polishing process must be performed discontinuously by setting the polishing angles separately, which reduces the processing efficiency. 2) In order to make the sliding surface 10 have the ideal shape shown in FIG. 2, it is necessary to relatively delicately control the amount of polishing when polishing the four surfaces, but this control is difficult in practice.

More specifically, if the amount of polishing is insufficiently controlled, the disk sliding surface will take on various shapes as shown in FIGS. 3A, B, and C, for example.

The disk sliding surface 10a shown in FIG.
Since the amount of polishing ' is non-uniform, it is asymmetrical with respect to the center line 14. The disk sliding contact surface 10b shown in FIG. show. In contrast to the disk sliding surface 10b, the disk sliding contact surface 10c shown in FIG. Furthermore, the disk sliding contact surface may have a combination of the above relationships. The actual dimensions of the disk sliding surface 10 in FIG. 2 are, for example, the electrode width a=0.8 μm, and the lengths of the contour lines 11, 11', 12, and 12/ are each about 10 μm.
It is about μm.

In this case, even if the polishing amount of each polishing surface 3, 3/, 4, 4' is controlled to about 1 μm, the control is insufficient and the disk sliding surface 10 becomes considerably asymmetric.
Therefore, the amount of polishing needs to be controlled quite strictly. FIG. 4 shows one polishing step in manufacturing the regenerated needle 1. As shown in FIG.

Specifically, the drawing shows a state during a polishing process in which a rod-shaped needle material 20 (indicated by a solid line and a dashed-dotted line) having a rectangular cross section is polished to obtain an initial polished surface 3. The needle material 20 has one longitudinal side surface 20a.
An electrode 21 is preliminarily formed on the shank 22 and set in a predetermined attitude relative to the polishing medium 23 rotating in the direction of arrow A. That is, the electrode surface forms an angle γ with respect to the polishing medium 23, and the electrode edge 20b in the needle material forms an angle γ with respect to the polishing medium 23.
3, the tip edge 20c of the needle material is the polishing medium 23
The angle ε is set with respect to the angle ε. The polishing process is
In this setting state, the needle material 20 is reciprocated in the direction of the arrow B, which is perpendicular to or approximate to the arrow A, or (furthermore) swung in the direction of the arrow C about the center 24. At this time, a force in the direction of arrow D is applied to the needle material 20 by a load application device (not shown), so that the needle material 20 is constantly pressed into contact with the surface of the polishing medium. The polishing process is carried out until a predetermined surface 25 (corresponding to the surface 3 in FIG. 1) is obtained, and an edge 26 (corresponding to the edge 5 in FIG. 1) shown by a two-dot chain line appears. In the above-mentioned polishing process, the amount of polishing is controlled by a temporal control method that controls the polishing time, or a trial control method that observes the amount of polishing using a microscope. When forming other surfaces, the above settings are made for each surface and polishing is performed.

Therefore, in order to obtain the sliding surface 10 having the shape shown in FIG. It is necessary to determine positional accuracy very well.

Therefore, this regenerated needle 1 was obtained by hand-made trial work by a hot-wire processing person, and there were problems in that it was not suitable for mass production and was expensive. The applicant has also proposed a regenerated needle as shown in FIG. In this regenerated needle 30, 31 is the outer surface of the needle material, and 32 is the electrode surface. The electrode is a wide part 33,
A sector-shaped part 35 defined by a pair of edges 34, 34', and a narrow part 3 defined by edges 36, 36' and having a width 37
Consists of 8. 39 and 39' are polishing planes which form a triangular disk sliding surface 40, and ridge lines 41,
4" and define the introduction ridge line 42.

The regenerated needle 30 is manufactured by forming an electrode pattern on a flat plate of the needle base material by masking, then slicing and polishing the flat plate to form the shape of the needle base material, and then making sure that the narrow part 38 is located at the center. Surfaces 39, 39' are polished.

In this manufacturing method, the number of surfaces to be polished is smaller than in the above case, and the control of the polishing process is also easier than in the above case.

However, there are problems with the electrode pattern forming process. That is, since the width 37 is extremely small, approximately 0.8 μm, the narrow portion 38 cannot be formed with high precision using the existing patterned mask exposure method, and patterning using a laser or electron beam is required. There was a problem that required large-scale manufacturing equipment. Further, in both of the regenerated needles 1 and 30, the disk sliding surfaces 10 and 40 both have a vertex portion.

For this reason, there is a common problem that stress concentration tends to occur at the apex corner portion during polishing, and chipping is likely to occur. The present invention solves the above problems,
An embodiment will be described below with reference to the drawings.

FIG. 6 shows the overall shape of a regenerated needle obtained by the method of manufacturing a regenerated needle according to the present invention, and FIG. 7 shows an enlarged view of the shape of the disk sliding surface in FIG. 6. FIGS. 8A to 8D show manufacturing steps of an embodiment of the regenerated needle manufacturing method according to the present invention. In the capacitive disk-shaped recording medium reproducing needle 50 shown in FIG.
Reference numeral 51 indicates an electrode forming surface having this surface angle relative to the outer surface 52 of the needle material, 53 indicates an electrode formed continuously on the surfaces 51 and 52, and 54a and π54b indicate a predetermined angle η (uniform) relative to the electrode surface. It is a plane that forms 〈η〈π).

55 is a curved surface corresponding to a part of the cylindrical side surface, and both circumferential ends thereof are geometrically continuous with the flat surfaces 54a and 54b.

That is, the planes 54a and 54b each serve as contact planes with the curved surface 55, and no apex angle is formed at the connection between them.
56 is a line that conveniently indicates the connection between the curved surface 55 and the flat surface 54a (in reality, this line 56 does not appear).

57a and 57b are ridgelines formed by the flat surfaces 54a and 54b and the electrode forming surface 51.

The electrode 53 has a shape defined by the ridge lines (edges) 57a and 57b, and has an opening angle θ. Note that the curved surface 55 and the pair of flat surfaces 54a and 54b are formed in one polishing process as described later.

Reference numeral 58 denotes a disk sliding surface, which is formed at an appropriate angle with respect to the surface 51, and has a shape shown enlarged in FIG.

The shape of this disk sliding contact surface 58 differs depending on the angle with respect to the surface 51, and may also be asymmetrical depending on the processing method described later. It has a laterally symmetrical shape. Further, in FIG. 6, reference numeral 61 indicates a virtual surface including the sliding surface 58. 62a and 62b are linear edges of the planes 54a and 54b relative to the virtual plane 61, and have an angle η1 (within η1<π) with respect to the electrode edge π59.

63 is a curved edge of the curved surface 55 relative to the virtual surface 61, and has a substantially constant curvature throughout.

The linear edges 62a, 62b and the curved edge 63 are as follows:
The points 64a and 64b are formed continuously without forming an apex angle. Further, a point 65 indicates the leading edge on the introduction side.
As is clear from FIG. 7, this disk sliding surface 58 is
Since the electrode edge 59 has no apex except for both ends, and both the tip end and the end of the widest part on the introduction side are curved, disk damage during regeneration occurs in the case of conventional regenerated needles. is significantly reduced compared to

Further, the disk sliding surface 58 has a maximum width W and a relative length l in the scanning direction. Next, a method for manufacturing the regenerated needle 50 having the above structure, which is a main part of the present invention, will be explained with reference to FIGS. 8A to 8D.

Figure A shows a needle material 70.

The needle material 70 is, for example, a rod-shaped body with a square cross-sectional shape (
It is 0.2m1L x 0.2 pilgrimage x 4mO. A surface 71 in the needle material 70 is a reference surface during processing. This needle material 70
is polished so as to form an angle ζ with respect to the reference surface 71,
As shown in Figure B, the electrode formation surface (
A needle material 73 with an electrode-forming surface formed thereon having a polished surface 72 is obtained.

This electrode forming surface 72 is the surface that will eventually appear as the edge of the electrode and is also the surface on which the electrode is attached and formed, so it must be an extremely flat surface. This side 7
No. 2 is obtained as a scratch-free surface by a mechanical/chemical polishing method using SlO2 and water. Next, a metal material such as Hf, Ti, Ta, etc. is attached to the surfaces 71 and 72 of the needle material 73 by sputtering or vapor deposition to a thickness of about 3000λ or less, and the electrode 53 is placed over the entire surfaces 71 and 72. form.

As a result, a needle material 74 with electrodes formed thereon as shown in FIG. 3C is obtained. This electrode-formed needle material 74 is fixed to the shank 75 with its longitudinal axis 74a aligned with the axis 76 of the shank 75, and is rotated in the direction of the arrow E with respect to the rotating polishing medium 77 in a predetermined manner as shown in FIG. The curved surface 55 in FIG. 6 and the pair of flat surfaces 54a and 54b are simultaneously polished and formed, leaving a part of the electrode forming surface 72.

Figure D shows the state immediately before the start of this polishing process. A polishing device (not shown) having this shank 75 rotates the shank 75 within a predetermined angular range around an axis 76 in clockwise and counterclockwise directions (as seen from the needle material side) as shown by arrows G and H. A mechanism for moving the shank 75 minutely in the direction of arrow I, that is, a polishing amount feeding direction, and a mechanism for variably adjusting the angle of the shank 75 with respect to the polishing medium 77. ing.

The shank 75 (needle material 74) is set to have an inclination angle of λ with respect to the polishing medium 77 (an angle in a virtual plane Z that is perpendicular to the polishing medium 77 and includes the center line 76). Note that the angles formed by the center line 78 and the rotation axis 76 in a virtual plane Y passing through the center line 78 of the electrode forming surface 72 and including the rotation axis 76 are different. Furthermore, the angle formed by the polishing medium 77 and the virtual cut edge 79 of the electrode 53 on the electrode forming surface 72 cut by the virtual plane P perpendicular to the rotation axis 76 is η. Set to . The shank 75 is at the angle η.

The position defined by is the clockwise end indicated by arrow G,
It repeatedly rotates counterclockwise and clockwise alternately within the range of 2π-2ηo. At the end of the counterclockwise rotation of the shank 75, indicated by the arrow H, the surface 72 is at an angle η with respect to the polishing medium 77. The rotational position will be . Furthermore, the shank 75 linearly reciprocates in the directions of arrows Fl and F2 perpendicular to the rotational direction of the polishing medium 77. The needle material 74 contacts and presses the polishing medium 77 while rotating and reciprocating as described above, and is fed minutely in the direction of the arrow 1 to perform the polishing process. During the reciprocating process of the needle material 74, a curved surface (cylindrical side surface) 55 is formed, and flat surfaces 54a and 54b are formed at the final end of rotation. For example, when this polishing process is performed up to the intersection point 80 between the rotation axis 76 and the electrode surface 53, each of the polished surfaces 55, 54a, 54b, and 51 will reach the point 80, as shown by the two-dot chain line in FIG. A semi-finished regenerated needle 81 that converges to one point is obtained. This polishing process maintains mechanical and dimensional accuracy regarding the surface runout of the polishing medium 77, the rotation accuracy of the shank 75, and the relative positional relationship between the polishing medium 77 and the needle material 74.
Therefore, extremely good processing accuracy and reproducibility can be obtained. Furthermore, the amount of polishing is not indirectly controlled by polishing time, etc. as in the conventional case, but is controlled by the feed amount of the polishing device, and as polishing devices become more precise, it is controlled more precisely. Ru. Furthermore, the regenerated needle 50 is different from the conventional regenerated needle 1.
The four polishing planes in the above are replaced with two planes and one curved surface, but the polishing of these surfaces is all included in one polishing process, and there is no discontinuity in the polishing position during the polishing process. No switching is necessary. As a result, according to the method for producing recycled needles according to this embodiment, the efficiency of polishing can be greatly improved compared to the conventional method, and recycled needles with stable quality can be produced with good mass productivity, and furthermore, polishing can be automated. It is possible to improve the possibility of

Furthermore, since the apex corner is not formed during the polishing process, there is no occurrence of chipping at the apex corner during the process as in the conventional example.

Also, when polishing is performed while rotating the needle material mentioned above,
Since the part to be polished in the longitudinal direction of the needle material is a part of its tip end, the amount of polishing is relatively small.In addition, in the above polishing process, even if the polishing medium 77 is rotated in the opposite direction to the arrow E, good.

Furthermore, when moving the needle material 74 in the direction of arrow F1, it is rotated in the direction of arrow H, and conversely, when moving it in the direction of arrow F2, it is rotated in the direction of arrow G. It is also possible to match the phase of the linear reciprocating direction and the shank rotation angle. As a result, one plane 54a of the semi-finished regenerated needle 81 is polished in the direction of arrow J in FIG. A portion 77b diametrically opposite to 77a is polished in the direction of arrow K in FIG.
As a result, the electrode edges 57a and 57b become open ends in the direction of relative movement with the polishing medium 77 during electrode surface edge polishing, and the electrode edges 57a and 57b are formed evenly and sharply. Note that the linear movement direction of the needle material and the phase of the shank rotation angle can also be set to match in a relationship opposite to the above. Further, the polishing process may be performed up to the vicinity of the point 80.

For example, the polishing process is stopped before reaching point 80 (
), and the tip of the semi-finished recycled needle is
The result will be as shown in Figure A. On the other hand, if the amount of polishing is increased and the needle is polished to the point 80a, the tip of the semi-finished regenerated needle will become as shown in Figure B. By varying the final polishing position in this manner, the disk sliding surface (indicated by the two-dot chain line in each figure) can be formed by appropriately changing the ratio of its area to the electrode width. Incidentally, the amount of polishing in the above-mentioned polishing process is considerably smaller than in the conventional example, and the polishing process can be carried out in a correspondingly shorter time and with less occurrence of troubles such as electrode chipping.

Also, the shank 75 and the polishing medium 77 during the polishing process described above.
The angle λ formed by
Fixed.

That is, there will be no inconveniences such as restrictions on the fixing method or the shank being polished during polishing. From a geometrical consideration, the angle λ can be expressed as follows in relation to the other angles ζ, θ, and ηo.

ρ Now, if we consider a practical value as an example, θ
= 2 examples, ηo = 45, ζ = 30, so λ =
It becomes 22.9o.

As a result, the opening angle θ of the electrode 53 is extremely small, and even if the disk sliding surface is worn and the area increases, an extremely practical needle shape is obtained in which the electrode width does not increase. In the case of the conventional example, the angle of the shank 22 with respect to the polishing medium 23 is uniquely determined by the opening angle α of the electrode 2, as shown in FIG.

When the angle α is of the order of 2, the shank 22 is attached to the polishing medium 2.
3, the method of fixing the needle material is restricted, and the shank 22 is also polished at the same time when the needle material is polished, resulting in the shank being discarded every time the needle material is polished. Finally, the tip of the semi-finished regenerated needle 81 is polished down to the virtual surface 61 in FIG. 6 to form a sliding surface 58, and the completed regenerated needle 50
get.

Here, the shape of the sliding surface 58 changes depending on the angular position of the virtual surface 61 with respect to the axis 76.

If the virtual surface 61 is perpendicular to the axis 76, the curved edge 63 in FIG. If there is, the edge 63 becomes a part of the ellipse. In addition, in the above embodiment, the electrode material is deposited and formed in advance, and then polishing is performed to define the electrode edge. After this, a step of attaching an electrode material to this surface can also be adopted.

In particular, when diamond is used as the needle material, there is a risk that the electrode material will oxidize due to heat generated during polishing, so it is desirable to adopt a process sequence in which the electrode is attached after polishing. As described above, according to the method for manufacturing a capacitive disk-shaped recording medium reproducing needle according to the present invention, electrode formation is performed by polishing a rod-shaped needle material at a predetermined angle with respect to the longitudinal axis thereof. The width of the electrode forming surface is determined by rotating the rod-shaped needle material alternately within a predetermined angle range around an imaginary axis that forms a predetermined angle with the electrode forming surface, leaving only a part of the electrode forming surface. Since the dimensions are defined and the electrode shape and the sliding surface with respect to the disk-shaped recording medium are determined,
The polishing process to obtain a predetermined electrode shape and sliding contact surface can be performed with high efficiency and precision without changing the setting position, and it is possible to mass-produce recycled needles with stable quality. The amount of polishing can be reduced, and the amount of polishing can be controlled mechanically, improving the possibility of automation of polishing. It has excellent features such as being able to more easily form electrodes in a predetermined shape by forming the electrodes on the electrode forming surface.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an example of a conventional regenerated needle, Fig. 2 is a view showing the shape of the disk sliding surface of this regenerated needle, and Figs. 3 A to C show the manufacture of the regenerated needle shown in Fig. 1, respectively. Figure 4 is a diagram showing the polishing process for producing the recycled needle of Figure 1, and Figure 5 is a diagram showing various shapes of the disk sliding surface obtained when the control in the polishing process is insufficient. FIG. 6 is a perspective view of another embodiment of a conventional recycled needle, FIG. 6 is a perspective view of a recycled needle manufactured by the method of manufacturing a recycled needle of the present invention, and FIG. 7 shows the shape of the disk sliding surface of this recycled needle. Figures 8A to 8D are diagrams illustrating an embodiment of the method for manufacturing a regenerated needle according to the present invention in the order of steps,
FIGS. 9A and 9B are enlarged views showing the shape of the tip of the semi-finished recycled needle when the amount of polishing during the polishing process shown in FIG. 8D is changed. 50... Capacitive disk-shaped recording medium reproducing needle, 5
1... Electrode formation surface, 53... Electrode, 5
4a, 54b...Plane, 55...Curved surface (cylindrical side surface), 56...Ridge line, 57a, 57
b...Ridge line (edge), 58...Disc attachment surface, 62a, 62b...Straight edge, 6
3... Curved edge, 70... Needle material,
71... Reference surface, 72... Electrode forming surface (polished surface), 73... Electrode forming surface formed needle material, 74... Electrode formed Needle material, 75...
・Shank, 76... Axis line, T11...
- Rotating polishing medium, 79... virtual cutting edge, 80
, 80a... point, 81... semi-finished regenerated needle.

Claims (1)

[Scope of Claims] 1. Manufacture a reproduction needle that relatively scans tracks of a disc-shaped recording medium on which information signals are recorded as changes in geometric shape and reproduces the information signals as changes in capacitance. The method includes the step of polishing the rod-shaped needle material at a predetermined angle with respect to the longitudinal axis to obtain an electrode forming surface on which an electrode is formed, and the step of polishing the rod-shaped needle material at a predetermined angle with respect to the electrode forming surface. The width of the electrode forming surface is polished by rotating the electrode forming surface alternately within a predetermined angle range ending at a position where the electrode forming surface forms a certain angle with the polishing medium around the axis, leaving a part of the electrode forming surface. A method for manufacturing a capacitive disc-shaped recording medium reproducing needle, comprising the steps of regulating dimensions. 2. The static electrode according to claim 1, wherein the electrode is formed on the electrode forming surface after polishing the electrode forming surface and before the step of regulating the width dimension of the electrode forming surface. A method for manufacturing a capacitive disk-shaped recording medium playback needle.