JPS6158889B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A reproducing element is placed on a recording trace in an information recording medium disk (disc) having a recording trace formed by arranging bits corresponding to an information signal in a spiral or concentric pattern. By sliding the playback stylus of a pickup (pick-up) into contact and detecting the change in capacitance value that occurs according to the state of the information signal in the recorded trace as a change in the amount of electricity, the information signal that is recorded at high density on the disk can be detected. The so-called capacitance value change detection type information recording and reproducing method that reproduces the
Since the information signal in the recording trace on the disk is read by detecting the change in capacitance value using the electrode provided on the playback needle, the thickness dimension of the electrode on the playback needle described above is used as the information signal. The length of the corresponding bit (the size of the bit in the direction in which the recording trace extends) can be made sufficiently small to increase the resolution, so even if the rotational speed of the disk is low, the information In addition to being capable of recording and reproducing signals, it also has many other advantages, so research into its practical application has been promoted.

Incidentally, a disk on which information signals are recorded at high density has a small track pitch and a significantly short recording wavelength on the disk surface. The reproduction needle of the reproduction element used for reading has an electrode thickness that is less than 1/2 of the shortest recording wavelength on the disk surface, and a recording trace spacing so that crosstalk from adjacent recording traces does not become a problem. An electrode part is formed of a conductive material on the electrode forming surface of the sliding contact surface main body so that an electrode end portion having an electrode width approximately equal to , can appear on the sliding contact surface. However, the above-mentioned electrode portion to be formed on the regenerated needle must be attached to the regenerated needle body with a sufficiently large adhesion force so that it will not peel off from the sliding contact surface body even when it comes into sliding contact with the disk surface. In addition, the electrode portion is configured to exhibit a low electrical resistance value so that the information signal can be detected in a condition that exhibits a good C/N ratio. That is required.

In other words, the reproducing needle of the capacitance value change detecting type detecting reproducing element records data on the disc using the electrode part, mainly the electrode end, while its sliding surface is in sliding contact with the disk surface which is rotating at high speed. Information is detected by changes in capacitance, but if the adhesive force between the regenerating needle body and the conductive material coating that makes up the electrode part is small, the high-speed rotating disk The electrode part may be peeled off from the regenerated needle body due to external force applied to the end of the electrode that is in sliding contact with the regenerated needle, and the regenerated needle may become unusable.
Alternatively, the electrode portion may be peeled off from the regenerated needle body due to an external force applied to the electrode portion when processing the regenerated needle into a desired external shape, or when shaping the electrode portion into a desired shape, etc. It becomes difficult to obtain a completely regenerated needle, which causes problems such as a decrease in the yield when manufacturing the regenerated needle.

In addition, in the capacitance change detection playback element, the capacitance between the electrode part of the playback needle and the information surface of the disk is measured at the tuning frequency of a tuning circuit to which a signal of a fixed frequency is given from a high-frequency oscillator. It is used as all or part of the capacitor for determining Normally, a signal whose amplitude has been modulated by the recorded information is extracted and amplitude demodulated to obtain the recorded information (FM wave) on the disk, but the information signal on the disk is electrostatically modulated. The electrode part of the regeneration needle used to detect changes in capacitance value is used as an element in the resonant circuit as described above, so the electrical resistance of the electrode part is a function of the sharpness of the resonance of the resonant circuit. This is a factor that determines Q. Therefore, when the electrical resistance of the electrode part is large and the Q of the resonant circuit becomes low, the resonant frequency changes from ₂ to ₁ as shown in the first diagram due to the change in capacitance value, and the resonance curve changes. , the variation α of the resonance curve at the position of the frequency h of the signal supplied from the high-frequency oscillator to the resonant circuit becomes extremely small, and therefore it can be detected by the change in the capacitance value. The information signal of the disc that has been processed will be output from the reproducing element as a signal with a poor C/N ratio. In Figure 1, the curve indicates the resonance curve of the resonant circuit when the electrode part of the regeneration needle is constructed with a small electrical resistance value, and the frequency of the resonant circuit changes as the capacitance value changes. When changing from ₂ to ₁ , the amount of change β in the resonance curve at the position of frequency h of the signal supplied from the high-frequency oscillator to the resonant circuit is larger than the amount of change α described above, and therefore, the reproduction A reproduced signal with a good C/N ratio can be obtained from the element.

As described above, the regeneration needle of the regeneration element that detects changes in capacitance requires several factors, such as the adhesion between the electrode part and the regeneration needle body to be sufficiently strong, and the electrical resistance of the electrode part to be low. The conditions must also be satisfied.

Conventionally, for the electrode part of a recycled needle, a conductive material is selected that can form a large deposit with the wear-resistant, high-hardness material used for the recycled needle body, and the conductive material is used as the material for the recycled needle. The most common method has been to deposit a film of a desired thickness on the electrode forming surface of the main body by sputtering or vapor deposition. For example, when the regenerated needle main body is made of diamond, The electrode part is made of titanium, and if the recycled needle body is made of sapphire, the electrode part is made of hafnium, which results in low electrical resistance.
In addition, the electrode part was attached to the regenerated needle body with sufficient adhesion force to the extent that it did not cause any major problems in practical use. It has been difficult to obtain regenerated needles exhibiting these characteristics.

The applicant company has been promoting practical research on recycled needles in order to easily provide recycled needles that have a long life and stable regeneration characteristics. A regenerated needle using diamond as the material for the needle body was completed by forming a conductive layer of the diamond's own carbon on the electrode-forming surface of the needle, and using this as an electrode.

In the regenerated needle having the above configuration, since the electrode is a conductive layer made of carbon of the diamond itself used as the material of the regenerated needle body, the electrode does not peel off during use of the regenerated needle. , it was possible to easily provide a regenerated needle that has a long life and exhibits good regeneration characteristics, but when trying to obtain a conductive layer of carbon with a low electrical resistance value of the diamond itself. for,
There were problems such as the long heat treatment time required, and improvement of these problems was desired.

The present invention solves the above-mentioned problems by forming an electrode coating of a conductive material with a required thickness on the conductive layer made of carbon of the diamond itself, which is provided on the electrode forming surface of the regenerated diamond needle body. The regeneration needle that solves the problem can be easily provided, and the specific contents of the capacitance value change detection regeneration needle of the present invention will be explained in detail below with reference to the attached drawings. .

FIG. 2 is a perspective view of one embodiment of the capacitance value change detection regeneration needle of the present invention;
In the figure, 1 is the regenerated needle body made of diamond, 2 is the electrode formation surface, 3 and 4 are the back surfaces adjacent to the electrode formation surface, and 5 and 6 are the introduction surfaces (however, the introduction surface 6
is a surface formed between the introduction surface 5 and the back surface 4 (not shown in the drawing), 7 is a sliding surface, and D is a surface formed between the sliding surface 7 and the rear surface 4. This line shows for reference the position of the disk surface that should come into sliding contact during operation.

In the regenerated needle of the present invention shown in FIG. 2, the electrode portion formed on the electrode forming surface 2 of the regenerated needle main body 1 is formed of the carbon of the diamond itself on the surface of the electrode forming surface 2, as shown in FIG. Since the electrode part is constituted by the conductive layer 8 and the electrode coating 9 made of a conductive material deposited on the conductive layer 8, the electrode portion has a sufficiently low electrical resistance value.
The reproduced signal is made to have a good C/N, and the electrode coating 9 is adhered to the conductive layer 8 made of diamond itself formed on the surface of the electrode forming surface 2 with good adhesion strength. Therefore, a regenerated needle without peeling of the electrode portion can be easily obtained.

In the regenerated needle of the present invention as described above, the conductive layer 8 formed of the carbon of the diamond itself on the electrode forming surface 2 of the regenerated needle is formed by, for example, using the diamond, which is the material of the regenerated needle body, with a trace amount of oxygen. A conductive layer made of the carbon of the diamond itself is formed on the surface of the material of the regenerated needle body by high-temperature treatment in a vacuum containing a small amount of oxygen or in an inert gas containing a trace amount of oxygen, and then the conductive layer is used to form an electrode. The conductive layer other than the part corresponding to the electrode forming surface 2 is removed by polishing so that only the part corresponding to the electrode forming surface 2 is left, or the conductive layer other than the part corresponding to the electrode forming surface 2 is removed by laser treatment. In addition to being able to be formed by irradiating energy rays such as light, X-rays, electron beams, gamma rays, heat rays, etc. to form a high-resistance material, for example, the conductive layer 8 described above can be formed by regenerating diamond. The needle body is irradiated with a laser beam or an electron beam in a vacuum containing a trace amount of oxygen or in an inert gas containing a trace amount of oxygen, and only a portion of the regenerated needle body that approximately corresponds to the electrode formation portion on the electrode formation surface is irradiated with a laser beam or an electron beam. However, here is a specific example of forming a conductive layer with a thickness of about 3000 angstroms on the surface of the diamond using the carbon of the diamond itself. is as follows.

i.e. diamond for example 15×
By heating the diamond to 1150°C in air at 10 ^-3 Torr and holding it there for 6 hours, a conductive layer about 3000 angstroms thick can be formed on the diamond surface.

4a to 5e and 5a to 5e show a conductive layer 8 made of carbon of the diamond itself formed on the surface of the electrode forming surface 2, and a conductive layer 8 deposited on the conductive layer 8 described above. FIG. 4 is a drawing illustrating a manufacturing process in the case of manufacturing the regenerated needle of the present invention described above, in which the electrode part is formed by an electrode coating 9 made of a substance, according to an example manufacturing method, and FIG. A case is shown in which a recycled needle is made using a diamond prismatic body as shown in Figure 4a as the material for the needle body, and a case where a diamond prismatic body as shown in Figure 5a is used as the material for the recycled needle body is shown in Figure 5. This shows the case where a regenerated needle is made using a cylindrical body.

First, as shown in FIG. 4b and FIG. A surface 11 inclined at a certain angle (for example, about 15 degrees) with respect to the surface of the prismatic or cylindrical body is formed near one end by polishing.

The material formed into the form shown in each figure b of Fig. 4 and Fig. ⁵ is
By heating at 1150° C. and keeping it as it is for 6 hours, a conductive layer 8 of about 3000 angstroms is formed on the surface by carbon of the diamond itself. The materials with the conductive layer 8 formed on the surface as described above are shown in each C in FIGS. 4 and 5.
As shown in the figure.

Next, a thin film of a conductive material is formed on the surface of the material shown in each diagram C in FIGS. 4 and 5 by, for example, sputtering, vacuum evaporation, ion plating, or any other suitable method. For example, a thin film of titanium or hafnium is deposited. The thin film of conductive material may have a thickness, for example, in the range of 1000 to 3000 angstroms. In addition, in the above-described process, the thickness of the conductive layer 8 to be formed from the carbon of the diamond itself is 500 to 500 mm.
It may be chosen as desired within the range of 3000 angstroms, and the thickness of the conductive layer can be made as desired by varying the heating time. Each figure d in FIGS. 4 and 5 shows a material with a thin film of conductive material adhered to its surface.

The back surfaces 3, 4 and the introduction surfaces 5, 6 are formed by polishing on the materials shown in each d diagram in FIGS. 4 and 5.
As shown in each figure e in the figure, an electrode forming surface 2 having a narrow electrode opening angle (for example, about 6 degrees) is formed on the above-mentioned surface 11. The electrode forming surface 2 is provided with an electrode portion made of a conductive layer 8 and an electrode coating 9, and each of the sliding contact surfaces shown in FIG. 4 and FIG. Once formed, it becomes a completed recycled needle body.

In the manufacturing method for an example of a regenerated needle described with reference to FIGS. 4 and 5, a prismatic or cylindrical diamond is used as the material for the regenerated needle body. It is also possible to use a metal rod or a ceramic rod at the base.In this case, cheap natural scrap diamonds or cheap artificial diamonds can be used as diamonds. This has the advantage that inexpensive recycled needles can be obtained. In addition, when a metal rod such as a titanium rod is used, after processing the material into the shape shown in Figures 4e and 5e, it is heated in a vacuum containing a trace amount of oxygen. The electrode is placed in an inert gas containing medium or a small amount of oxygen, and an energy beam such as a laser beam or an electron beam is irradiated only on the electrode forming surface 2 formed on the diamond portion at the tip, so that the surface of the electrode forming surface is irradiated. By forming a conductive layer of the required thickness using the carbon of the diamond itself, the metal rod will not be oxidized during processing, and the bond between the metal rod and the diamond will not be separated by heat, and the diamond A conductive layer made of carbon of diamond itself can be formed on the surface of the electrode formation surface.
For the material on which the conductive layer is formed on the surface of the electrode forming surface as described above, the needle tip thereof is masked with masking material M as shown in Figure 6, and an electrode coating made of a conductive material is formed on the surface by sputtering, for example. law,
The regenerated needle can be obtained by applying a vacuum deposition method and then removing the masking material.

As the masking material M in FIG. 6, for example,
Soft aluminum that is 0.1 mm square and approximately 0.02 mm thick can be used. In this case, by sticking the needle tip of the material into the masking material M, the needle tip of the material will be approximately 20 micrometers thick. The portions are masked with the masking material M so that no conductive material is attached to those portions. The above masking amount of 20 micrometers is just an example, and the masking amount may be several micrometers, but the above masking amount is based on the amount of sliding contact when a sliding surface is formed at the tip of the regenerated needle. An amount of masking is required so that an electrode consisting only of the conductive layer is formed over a length of at least several micrometers from the surface.

Further, as described above, the method for manufacturing a regenerated needle using the masking material M can also be introduced into the method for manufacturing a regenerated needle described above with reference to FIGS. 4 and 5. That is, each d in FIGS. 4 and 5
Omitting the steps in the figure, each C in Figures 4 and 5
The material in the state shown in the figure is polished and the fourth
The shapes shown in each C in FIGS. 4 and 5 are made, and the tips of the shapes shown in each e in FIGS. The regenerated needle of the present invention can also be obtained by a regenerated needle manufacturing method in which a thin film of an electrically conductive substance is attached to the surface of the material.

As is clear from the detailed explanation above, the capacitance value change detection type regeneration needle of the present invention is
Since an electrode portion consisting of a conductive layer made of carbon of the diamond itself and an electrode thin film made of a conductive material deposited on the conductive layer is formed on the electrode forming surface 2 formed on the diamond, Even if the tip of the electrode thin film is sagging or the edge of the electrode thin film floats off the disk surface, the conductive layer formed on the surface of the electrode forming surface 2 ensures good reproduction of information from the disk. In addition, since the electrode thin film attached to the conductive layer works to lower the electrical resistance of the electrode part, the C/N is better than that of a regenerated needle in which the electrode part is composed of only the conductive layer. It is possible to easily obtain a reproduced signal,
According to the present invention, it is possible to easily provide a regenerated needle that eliminates the above-mentioned problems.

[Brief explanation of the drawing]

Fig. 1 is a curve diagram for explaining the problem, Fig. 2 is a perspective view of an embodiment of the regenerated needle of the present invention, Fig. 3 is an enlarged sectional view showing the structure of the electrode part, and Figs. e
Figures 5 and 5a to 5e are explanatory diagrams of the manufacturing process of the regenerated needle, and Fig. 6 is an explanatory diagram of the masking material. 1... Regenerated needle body, 2... Electrode forming surface, 3, 4
... Back, 5, 6 ... Introduction surface, 7 ... Sliding surface, 8
. . . conductive layer, 9 . . . electrode coating.

Claims (1)

[Claims] 1. A capacitance change detection type in which an electrode coating of a conductive material with a required thickness is formed on a conductive layer made of carbon of the diamond itself provided on the electrode forming surface of a regenerated diamond needle body. Recycled needle.