JPS5845099B2 - Regeneration needle of regeneration element that detects changes in capacitance value - Google Patents

Description

[Detailed Description of the Invention] An information recording medium disk (disk) having a recording trace formed by arranging PIDs corresponding to an information signal in a spiral or concentric form has a recording trace on the recording trace. By sliding the reproduction needle of the reproduction element (pickup) into sliding contact and detecting the change in capacitance value that occurs according to the state of the information signal in the recording trace as a change in the amount of electricity, the information recorded at high density on the disc can be detected. In the so-called capacitance value change detection type information recording and reproducing method that reproduces signals,
Information signals in the recording trace on the disk are read by detecting changes in capacitance using an extremely thin electrode provided on the playback needle, so information signals can be recorded and played back even at low disk rotational speeds. In addition to this characteristic, it also has many other advantages, and research into its practical application has been promoted.

Figures 1 and 2 show a regeneration needle (hereinafter sometimes simply referred to as a regeneration needle) of a regeneration element that detects changes in capacitance value.
In each figure, figure a is a front view of the regenerated needle as seen from its electrode side, figure b is a side view of the regenerated needle, and figure 0 is a side view of the regenerated needle. FIG. 3 is a plan view of a sliding surface with a disk.

First, in the conventional regenerated needle shown in FIG. A polished surface 1at1b that is polished so that the portion 2 shows a predetermined electrode width, and an introduction side wall surface 4a, 4.
It has a pentagonal sliding surface 3 surrounded by b, etc., and the sliding surface 3 has apex corners 5 to 7.

In the recycled needle shown in the first diagram, the electrode portion 2 is polished to a predetermined electrode width by polishing the polished surfaces 1a and ib, but the electrode width appearing at the edge of the sliding contact surface 3 is When an extremely small value such as approximately 0.8 μm or less is required,
When polishing the polished surfaces 1a and 1b in a state where an electrode portion having such a small electrode width can be obtained satisfactorily, the angle θ shown in FIG. Polished surface 1a, 1
It is extremely difficult to perform polishing on b.
In actual processing, polishing is performed on the polished surfaces 1a and 1b with the angle θ set to 30 degrees or more, for example, and in conventional recycled needles, a value of about 45 degrees is often adopted. (, the length l in the extending direction of the recorded trace on the sliding contact surface 3 of the conventional reproducing needle of the form shown in the first figure,
The length W in the width direction of the recorded trace was made to be approximately equal.

In addition, in the conventional regenerated needle shown in FIG. A polished surface 11a that is polished so that the portion 2 has a predetermined electrode width.

11b, a trapezoidal sliding surface 13 surrounded by an introduction side wall surface 14, etc., and has an apex corner 15° 16.

In the conventional reproduction needle shown in FIG. Although it can be made smaller than the ratio of the length 1 in the extending direction of the recorded trace in the reproducing needle shown in Fig. 1 and the length W in the middle direction of the recorded trace, the sliding contact surface of the reproducing needle shown in Fig. 2 The area of 13 is smaller than the area of sliding surface 3 of the regenerated needle shown in the first diagram.

By the way, when the playback stylus is attached to a cantilever that extends in the direction of extension of the recorded trace, if the length l of the sliding surface of the playback stylus in the direction of extension of the recorded trace is large, the disc The problem is that large output fluctuations occur during playback output due to surface runout, and if the area of the sliding surface of the playback stylus is small, there is a problem that the surface of the disk will deteriorate significantly. Experimental results also support the following points: 1. The presence of an apical corner on the sliding surface of the playback stylus causes a problem in that the disc is easily damaged.

A concrete explanation of the above-mentioned problems is as follows.

FIG. 3 shows that the playback needle main body S, which is fixed to the other end of the cantilever 20 whose one end is supported by the support member 21 in such a manner that it extends in the direction of extension of the recorded trace on the disk, is attached to the surface of the disk. This figure is for illustrating and explaining how it is affected by runout. In this figure, D is a disk, and A and B are the surfaces of disk D that are displaced by surface runout. This is an example of two positions.

Now, in view of the properties of the constituent materials, the molding process, the environment in which the disc D is used, etc., it is impossible to avoid the occurrence of surface runout in the P-P value on the order of several hundred microns during its rotational operation.

Disc D, which inevitably has surface runout as described above.
The playback needle whose sliding contact surface is in sliding contact with the surface of the disc D
If the entire surface of the sliding contact surface is in good sliding contact with the surface of the disk D when the surface is at the position OA in FIG. When the surface is at the position OB in FIG. 3, a portion of the sliding surface of the reproduction stylus rises from the surface of the disk D due to the rise in the position of the surface of the disk D.

This is natural considering that the cantilever 20 to which the regenerating needle main body S is attached has a finite length, and as the sliding surface of the regenerating needle moves upward as the disk D rises. When rising, the cantilever 20 rotates around the rotation center 22 of its support member 21, and the regenerating needle uses the front end of the sliding surface of the cantilever 20 on the introduction side or the front edge of the introduction side as a fulcrum to support the electrode. The formation surface side floats above the surface of the disk D.

In this way, if the distance between the electrode-forming surface side of the sliding contact surface of the reproducing needle and the surface of the disc D changes in accordance with the surface runout of the disc D, the output level of the reproducing signal will fluctuate. , it is not possible to obtain a good reproduction signal.

Now, the length between the virtual rotation center 22 of the cantilever 20 and the reproducing needle is L, the length in the extending direction of the recorded trace on the sliding surface of the reproducing needle is 1, and the displacement of the surface of the disk D is d.
Assuming that the amount of floating of the electrode end from the surface of the disk D is δ, the above-mentioned floating amount δ is approximately expressed by the following equation (1).

From the above equation (1), in order to reduce the amount δ of the electrode end floating from the surface of the disk D when surface runout occurs on the disk D, the length of the recording trace on the sliding contact surface in the extending direction is determined. It is necessary to keep the length of the cantilever 20 small, the length of the cantilever 20 to be small, and the surface runout of the disk D to be small, but as already mentioned, it is necessary to keep the size of the surface runout of the disk D small. As can be seen from the above, it is difficult to set the length L of the cantilever 20 to a dog.If the length L of the cantilever 20 is a dog, the mass of the mechanical system including the cantilever 20 increases, Resonance in the deflection mode is likely to occur (for example, when driving and displacing the playback needle under tracking control, it is difficult to maintain good tracking characteristics). , cannot be adopted, so in order to reduce the value of δ shown in equation (1) above, it is necessary to reduce the length l in the extending direction of the recorded trace on the sliding surface of the reproducing needle. It is said that

However, when trying to solve the above-mentioned problem by reducing the length 1 in the extending direction of the recorded trace on the sliding contact surface of the reproducing needle, it is necessary to simply reduce the length 1 in the extending direction of the recorded trace on the sliding contact surface. If only the shortening of S1 is done,
The reduction in the area of the sliding surface causes an undesirable phenomenon in which wear and tear on the surface of the disk D becomes significant.

Furthermore, if the shape of the edge of the sliding contact surface has an apex corner, the apex corner will dig into the surface of the disc D, causing damage to the surface of the disc or damaging the sliding contact surface of the playback stylus. It also happens that the apex corner is damaged by scratches on the disk surface.

The explanation so far has been based on the assumption that the surface of the disk D is flat, but if the disk D has a configuration in which information signals are recorded on both the front and back sides, From the point of view of protecting the information signal recording surface, it is important that the disk D is supported by the turntable in such a way that the information signal recording surface of the disk D and the turntable do not come into contact with each other. For this reason, in the above-mentioned case, the turntable T supports only the unrecorded areas on the inner and outer peripheries of the disk D, as shown in FIG. Department Ti,
Therefore, the surface of the disk D, which rotates while being supported by the turntable T, on the side that comes into sliding contact with the playback needle is slightly deformed into a concave shape. It has become.

The sliding contact state when the sliding contact surface of the playback needle comes into sliding contact with the surface of the disk D, which has been deformed into a concave shape due to the above-mentioned causes, is clear from, for example, what is shown in FIG. As shown in FIG.
Therefore, if still images are played for a long time in this state, the edge of the sliding surface of the playback needle will strongly contact the surface of the disc. will be damaged.

It is clear that damage to the disc surface due to this cause occurs even if the sliding contact surface area is large, and the extent of damage to the disc surface is due to the part of the playback stylus that strongly contacts the disc surface. , it is natural that the closer it is to the apex corner of the edge of the sliding surface, the larger it is.

In this way, the conventional playback needle illustrated in FIGS. 1 and 2 causes a large fluctuation in the output level of the playback signal due to the surface runout of the disk D, or causes a large fluctuation in the output level of the playback signal due to the surface runout of the disk D or the playback needle. It is not uncommon for the equipment to cause damage or destruction to the equipment (improvement was requested).

In the present invention, the reproducing needle main body made of a high hardness material having wear resistance has a length of 1 in the extending direction of the recorded trace on the disc as a sliding contact surface between it and the disc D, and When the length in the width direction is W, the relationship between the above-mentioned lengths l and W is l<W,
In addition, the contour has a shape in which no apex portion exists, and when viewed in the direction of the length W mentioned above, the central portion thereof is protruded compared to both side portions thereof. and an electrode end portion having a predetermined width and a predetermined thickness appears on one of the edges corresponding to the protruding central portion of the sliding contact surface. The present invention provides a regeneration needle for a capacitance change detection type regeneration element in which an electrode portion of a desired pattern is formed on a surface adjacent to a sliding contact surface by a thin film made of a conductive material. The various problems have been solved, and the contents of the reproduction needle of the capacitance value change detection type reproduction element of the present invention will be explained in detail below with reference to the attached drawings.

Figures 6a" and 6C are a side view (figure a) of an embodiment of the regenerated needle of the present invention, a front view (figure b) seen from the electrode part side,
and a plan view (Fig. C) of the sliding surface, and this Fig. 6a
In the regenerated needle shown in the figure "-C, the sliding surface has an oval planar shape.

In Fig. 6, S is the regenerated needle body, and the material used for the regenerated needle body is a wear-resistant, high-hardness material such as diamond or sapphire. A prismatic shape may also be used.

The recycled needle shown in FIG. 6 is an example in which a prismatic material is used as the material.

In the regenerated needle shown in FIG. 6, the periphery near the tip of the regenerated needle body S is polished to form an elliptical curved surface 25, and the tip of the regenerated needle body S is polished. ,
A sliding contact surface 24 having an oval planar shape as shown in FIG. 6C is formed.

The sliding surface 24 described above has a curved surface shape in such a manner that the central portion of the planar ellipse in the long axis direction protrudes beyond both end portions thereof. The situation is shown in the side view shown in FIG. 6a and the front view shown in FIG.

The sliding surface 24, which is a convex curved surface in the long axis direction, has a large radius of curvature.For example, the length of the sliding surface 24 in the long axis direction is When W is 10 μm, the difference in height between the center and both ends of the curved surface in the long axis direction is at most 0.5 μm.
It is about m or less.

Reference numeral 23a denotes an electrode portion attached to the elliptical curved surface 25 so that an electrode end portion having a predetermined shape and size appears at the edge of the sliding contact surface 24, and this electrode portion 23a is an upper portion of the regenerated needle body S. The electrode section 23 occupies a large area.

The electrode portion 23.23a described above is formed by depositing a material such as hafnium, titanium, or tantalum by sputtering or vapor deposition.

The playback needle main body S shown in FIG. 6 is configured such that the long axis direction of the sliding contact surface 24 is the width direction of the recording trace on the disc, and the short axis direction of the sliding contact surface 24 is the extension direction of the recording trace on the disc. It is used by being attached to a cantilever extending in the direction of arrow X in FIG. 6C.

In the reproducing needle shown in FIG. 6, the length l of the sliding contact surface 24 in the short axis direction, that is, the length 1 of the sliding contact surface 24 in the extending direction of the recorded trace, is reduced, so that the disc D
Due to surface runout, the amount of floating of the electrode end from the disk surface can be reduced, thereby suppressing fluctuations in the reproduction signal output level due to surface runout of the disk. By increasing the length W, that is, the length W of the sliding surface 24 in the width direction of the recording axis, the area of the sliding surface 240 can be increased and wear of the disk can be reduced. Since there is no apex on the edge of the sliding contact surface 24, damage that may occur to the disc and the playback stylus during playing can be prevented. The curved surface is more convex than the edge, so if the playing surface of the disc is bent in a concave manner, the disc will not be damaged even if it is played for a long time in still playback mode. There is nothing to be done.

An example of the size of the sliding surface when the sliding surface 24 is oval-shaped is 1=5 μm and 1W=10 μm.

The explanation so far has been about an embodiment in which the planar shape of the sliding surface 24 is an ellipse as shown in FIG. It has a sliding contact surface that has a planar shape as shown in Figures C2d and e, and exhibits a curved shape such that the center portion thereof protrudes more than the end portions in the width direction of the recorded trace on the sliding contact surface. It can be implemented as a

In FIG. 7 a"e, ■ is the length of the recording trace on the sliding surface 24 in the extending direction, and W is the length of the recording trace on the sliding surface 24.
The length in the width direction of the recording trace in each of the sliding contact surfaces 24 shown in each of these figures satisfies the relationship 1<W with respect to the size of 1 and W described above. As a result, it is possible to reduce fluctuations in the reproduction output caused by surface runout of the disk, and to increase the area of the sliding contact surface to reduce wear on the disk. There is no apex corner on the edge of the disk, and there is a sliding surface with a curved shape in which the center part protrudes more than the edge in the width direction of the recording trace on the sliding surface 24. Damage to the recycled needle can be effectively prevented.

It goes without saying that the regenerated needle of the present invention is not limited to having a planar sliding surface as illustrated in FIGS. 6 and 7.

As is clear from the above explanation, in the regenerated needle of the present invention,
By setting the relationship l<W between the length ■ and the length W on the sliding surface, and reducing the length l in the extending direction of the recording trace while keeping the area of the sliding surface large, the disk In addition, the change in the output level of the reproduced signal can be suppressed to a small extent while the wear of the slide contact surface is reduced, and there is no apex on the edge of the sliding contact surface, and the width of the recording trace on the sliding contact surface is By having a curved surface shape in which the center part protrudes more than the edges in the direction, damage to the disc and playback needle can be reduced or prevented, and if the playing surface of the disc is concave, it can be used for a long time. The disc surface will not be destroyed even when performing stealth playback, and furthermore, as the sliding contact surface is curved in advance as mentioned above, the sliding contact surface easily conforms to the disc. The present invention has a feature that, prior to the beginning of use of the playback stylus, it can be brought into sliding contact with the disc surface and started playing immediately without having to be mounted and polished with a polishing machine as in the conventional case. The regenerated needle satisfactorily solves all the problems of the conventional regenerated needles mentioned above.

[Brief explanation of the drawing]

Figures 1 a''-c and 2 a-c are a front view (each figure a), a side view (each figure), and a plan view of the sliding surface (each figure 0) of a conventional regenerated needle. ), Figure 3 is a side view to explain the condition of the sliding surface due to surface runout of the disc, Figure 4 is a side view to explain the deflection of the disc on the turntable, and Figure 5 is a side view to explain the state of the sliding surface due to surface runout of the disc. A partially vertical front view showing the state of sliding contact between the surface and the disk, FIG. A plan view of the sliding surface (FIG. 0) and FIGS. 7 a-e are plan views of the sliding surface of other embodiments of the regenerated needle of the present invention. S: Regeneration needle body, D: Disc,
3,13゜24・・・Sliding surface, 2,12.23
．． 23a... Electrode part.

Claims (1)

[Claims] 1. Sliding contact with a recording trace on an information recording medium disc having a recording trace formed by arranging bits corresponding to an information signal, and changing the information signal in the recording trace according to a change in capacitance value. In the reproducing needle of the capacitance value change detection type reproducing element, which is equipped with an electrode part that can be extracted as a change in the amount of electricity, the reproducing needle main body is made of a wear-resistant, high-hardness material, and the information recording medium disk. As the sliding contact surface with the information recording medium disk, when the length in the extending direction of the recording trace on the information recording medium disk is l, and on the other hand, the length in the width direction of the recording trace described above is W, the above-mentioned lengths l and W are The relationship between l<W is established, and the shape has no apex in its outline, and when viewed in the direction of the length W mentioned above, the center of it The part has a curved surface shape in such a manner that it protrudes compared to both side parts thereof, and a predetermined part is provided on one of the edges corresponding to the protruding central part of the sliding surface. A capacitance change detection type reproducing element comprising a thin film made of a conductive material and having an electrode portion of a desired pattern on a surface adjacent to the sliding contact surface so that an electrode end portion having a width and a predetermined thickness appears. regenerated needle.