JPS6330702B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a scanning needle and a method for manufacturing the same, and an object of the present invention is to provide a scanning needle that improves molding workability and is inexpensive.

The information signal is brought into contact with a recording medium recorded as a change in geometrical shape, for example, a video disk recording video information, and runs relatively along the track of the video disk, thereby converting the video information, etc., into a static image, for example. As a scanning needle that detects and reproduces changes in capacitance, a track on the video disk has a groove for mechanically guiding the scanning needle (CED).
1) and a type without such grooves (VHD type), molded types as shown in Fig. 1 A and B have been proposed, respectively. In any scanning needle, the engaging surface that contacts the video disk must be molded to a predetermined size in order to obtain good playback characteristics.For example, in the case of a CED scanning needle, the width of the electrode tip 1 is defined as 2 μm, the height 2 is defined as 3 to 5 μm, and the length 3 in the track extending direction is defined as 3 to 5 μm. Such a complex needle tip shape is obtained by first removing the tip of a scanning needle starting material made of, for example, a natural diamond crystal formed into a prismatic shape to form slopes 4 and 5, and then performing the processing. The engaging surface 6 is moved by relatively running the object in a polishing groove (not shown) having a substantially U-shaped cross section.
However, in the conventional manufacturing method, in order to keep the length 3 within the specified value, the slope 4,
5 is precisely formed by the so-called wrapping process similar to that of the engaging surface 6. However, the scanning needle manufactured by this method requires considerable processing time and does not contribute to cost reduction. There are workability issues such as the amount of processing required when forming slopes 4 and 5 is extremely large, the need to access the machine for each of the two different sides, and the need to attach and detach the machine each time to monitor the degree of processing. This is because there are difficulties in Incidentally, when forming the slopes 4 and 5, the above-mentioned drawbacks can be eliminated by using a processing method that is rougher than the above-mentioned wrapping process, such as laser beam cutting or grinding process, but as shown in FIG. It is not possible to obtain a tip portion 7 with a good radius, and the tip portion 7 ends up having a roundness of, for example, about 10 μR. If this is removed when processing the engagement surface 6, the length 3 will no longer be able to be kept within the specified value. Figure 1 A,
In B, a hatched portion 8 indicates an electrode formed on the running surface, and an angle 9 is an angle formed between a ridge line 10 defining slopes 4 and 5 and an extending direction 11 of the track. I am trying to allow entry.

The present invention has been made in view of the above-mentioned drawbacks, and the present invention has been made in such a manner that the engaging surface for the video disc is compared to a set of slopes defining a ridge line that allows the relative approach of the video disc with a predetermined opening angle. It is an object of the present invention to provide a scanning needle with smoothed roughness and a method for manufacturing the same.

For convenience of explanation, first, one embodiment of the method for manufacturing a scanning needle according to the present invention will be described. Using natural diamond crystal (hexoctahedron) as a starting material, the third
A scanning needle starting material 12 in the shape of a rectangular parallelepiped shown in FIG. The ejection surface (corresponding to the electrode forming surface) 13 of the scanning needle starting material 12 is processed into a mirror surface by wrapping processing. Next, each of the plurality of scanning needle starting materials formed in this manner is bonded and fixed to each comb tooth of the comb tooth-shaped jig 14 (FIG. 3B). Next, each of the scanning needle starting materials supported in this manner is irradiated with a laser beam from the running surface 13 side of the scanning needle starting material 12 using a laser beam processing machine to form a ridgeline 15 as shown in FIG. forming a pair of slopes 16, 17 defined by. In the figure, 18 is the cut by the laser beam, 19 is the cut residue, 20 is the inclination angle of the ridge line 15 with respect to the video disk surface 21, and 22 is a set of slopes 16, 1.
This is the included angle of 7. The laser has a wavelength of 1.06μm,
It is a single mode, continuous wave type Nd:YAG laser, which performs cutting by oscillating it in the form of a Q-switch pulse. The smaller the beam diameter, the better the results, and the calculated value is about 7 μm. When cutting under these conditions, the width of the cutting allowance 18 is 20~
The diameter is about 30 .mu.m, and the tip of the needle has a sag 23 of about 10 .mu.mR, as shown by hatching in FIG. 3D. This sagging is particularly noticeable at the tip of the needle where thermal energy is concentrated.

The scanning needle material processed by this laser beam is shaped as shown in FIG. 4A. Each of the ridge lines defining the pair of slopes 16 and 17 has a sag shown exaggeratedly by a wavy line, and this sag has directionality in the irradiation direction 24 of the laser beam.
Next, in order to obtain sharpness at the tip of this scanning needle material, the scanning needle material is tilted onto a polishing disk 27 having a polishing groove 26 with a predetermined opening angle 25, as shown in FIG. 28 to press the
The wrapping process is performed by moving the two relative to each other. FIGS. 4D, 4E, and 4F show a perspective view, a side view, and a front view of the tip of the scanning needle material subjected to this processing. A pair of second slopes 32 and 33 are provided, which are smoother than the slopes 17 and whose included angle 29 is larger than the included angle 22 and whose inclination angle 31 of the ridge line 30 with respect to the video disk surface 21 is smaller than the inclination angle 20. ing. 34 is a ridge line that defines the first slope 16 and the second slope 32.

Next, electrode metal 35 (fifth, fifth and third (See Figure 6)
form. Next, in order to obtain a scanning needle suitable for the CED method, the scanning needle material 12 is processed as shown in FIG.
The electrode 35 is placed in contact with a polishing plate 37 having a 35-degree diameter so that its surface is substantially perpendicular, and the two are moved relative to each other.On the other hand, in order to obtain a scanning needle suitable for the VHD system, the processing shown in FIG. 6 is carried out. That is, the scanning needle material 12 is placed on a polishing plate 40 having a polishing groove 39 whose radial cross section is approximately V-shaped and whose opening angle 38 is a predetermined angle, so that the surface of the electrode 35 is with respect to the extending direction of the polishing groove 39. The seventh
A scanning needle having a needle tip shape as shown in FIG. 8 is molded.

Next, these scanning needles will be explained. As mentioned above, the scanning needle in FIG.
The scanning needle shown in the figure is compatible with each VHD type video disk player, and is equipped with a scanning needle base 50 and an electrode 52 formed on the scanning surface 51 of the scanning needle base 50. The needle base 50 has at its tip a ridgeline 55 that allows relative entry of a track formed on the video disk 53 with a predetermined opening angle 54, and a set of slopes 56, 57 that define the ridgeline 55. , an engagement surface 5 that comes into contact with the track
8, 59, and the above-mentioned running surface 51, and in particular, the surface roughness of the engaging surfaces 58, 59 is smoother than that of the pair of slopes 56, 57. In the scanning needle of FIG. 7, the engaging surface 58 is
It is formed into a substantially U-shaped surface that extends toward the running surface 51 side of the ridge line 55 and engages with the groove wall of the track groove so as to fit into the V-shaped track groove of a CED video disk. In the scanning needle of FIG. 8, the engaging surface 59 is formed into a plane parallel to the track surface of the VHD video disc and having a width 60 larger than the track pitch. Regarding the engaging surfaces 58 and 59, the length 3 of the scanning needle tip in the track extending direction described in connection with FIG.
In order to define the angle within a predetermined value, each scanning needle has an inclination angle (α ₁ ) 61 between the engagement surfaces 58 and 59 and a pair of slopes 56 and 57 that is equal to that of the first ridge line 55 (α ₂ ) A set of second ridges defined by the second ridge line 62 which is smaller than the second ridge line 54 and whose included angle (β ₂ ) 63 of the slope is larger than that (β ₁ ) 64 of the first slopes 56 and 57. It is provided with slopes 65 and 66. The surface roughness of the second slopes 65 and 66 is approximately the same as that of the engagement surfaces 58 and 59, and is smoother than that of the first slopes 56 and 57.

FIG. 9 shows another embodiment. Fourth
Instead of performing the processing shown in B and C of the same figure on the scanning needle material formed as shown in FIG.
As shown in the figure, the sag 23 is removed by wrapping the running surface 51 at a predetermined angle. After performing this processing, electrodes are formed on the running surface, and then as shown in FIG. 5 or 6.
By processing the figures, scanning needles similar to those in FIG. 7 or 8, respectively, can be obtained.

As described above, in the present invention, a set of slopes defining a ridgeline that allows the relative approach of a track of a video disc with a predetermined opening angle can be formed by a cutting process using a laser beam, for example, which is rougher than a wrapping process. Since it can be molded, the processing time for scanning needles can be significantly shortened, and inexpensive scanning needles can be supplied in large quantities, which is extremely useful. It goes without saying that the present invention is applicable not only to video disk players but also to scanning needles for various recording media. Further, the starting material is not limited to natural diamond as in the embodiments, but may be synthetic diamond or other material attached to the shank.

[Brief explanation of the drawing]

Figures 1A and 1B are perspective views of two types of conventional scanning needles.
FIG. 2 is a perspective view of the needle tip for explaining the forming operation. 3A to 3H are explanatory diagrams of the operation up to the first step of the manufacturing method of the present invention (FIG. 3D and 3E are a side view and a partially enlarged view of FIG. 3D, respectively), and FIG. A to F are operation explanatory diagrams of the second process (Figure 4 B,
(C) is a front and side view of the forming operation; Figures (E) and (F) are side and front views of the same figure (D); Figures 5 (A) and (B) and Figures 6 (A) and (B) provide different explanations of the final forming operation. FIG. 3 is a front and side view. A, B, and C of FIGS. 7 and 8 are respectively front, side, and bottom views of different embodiments of the scanning needle of the present invention. FIG. 9 is an explanatory diagram of another embodiment of the method of the present invention. Explanation of main figure numbers, 50...Scanning needle base, 52...
... Electrode, 55 ... First ridge line, 56, 57 ... A set of first slopes, 58, 59 ... Engagement surface, 51 ... Running surface, 62 ... Second ridge line, 65, 66 ... One The second slope of the group.

Claims (1)

[Scope of Claims] 1. A scanning needle that comes into contact with a recording medium on which an information signal is recorded as a change in geometrical shape and relatively runs along a track of the recording medium to detect and reproduce the information signal. , the scanning needle is equipped with a scanning needle base and an electrode formed on the scanning needle base, and the scanning needle base has an electrode formed on the scanning needle base at its tip. a set of first slopes defined by a first ridge line that slopes downward (the slope angle is α ₂ ) toward the recording medium and has an included angle of β ₁ ; The angle of inclination α ₁ is smaller than that of
(α ₂ > α ₁ ), and the included angle of the slope is β ₂ (β ₂ > β ₁ ), which is larger than the included angle of the first slope. A set of second slopes, an engagement surface that comes into contact with the track, and the running surface are provided, and the surface roughness of the engagement surface and the second slope is smoother than that of the first slope. A scanning needle characterized by: 2. The track has a substantially V-shaped groove in a radial cross section, and the engagement surface is a substantially U-shaped surface that extends toward the running surface side of the ridge line and engages with a groove wall of the V-shaped groove. A scanning needle according to claim 1. 3. The track does not have a groove for mechanically guiding the scanning needle, and the engaging surface is a plane parallel to the surface of the track and having a width larger than the pitch of the track. A scanning needle according to claim 1. 4. In a method for manufacturing a scanning needle that detects and reproduces the information signal by coming into contact with a recording medium on which the information signal is recorded as a change in geometrical shape and relatively traveling along the track of the recording medium, a column-shaped The tip of the scanning needle starting material is tilted downward with respect to the recording medium from the scanning needle's entry surface to its exit surface (the angle of inclination is α ₂ ).
a first step of forming a set of first slopes defined by first ridge lines and having an included angle of β ₁ ; An inclination angle α ₁ (α ₂ >
α ₁ ) is defined by a second ridge line with a downward slope, and the included angle of the slope is larger than the included angle of the first slope β ₂ (β ₂ > β ₁ ), and the angle is smaller than the first slope. A second step of forming a set of second slopes having a smooth surface roughness, and a third step of forming an engaging surface that comes into contact with the track and has a smoother surface roughness than the first slope. Characteristic scanning needle manufacturing method.