JPS58130457A - Recording stylus of detecting type for change in electrostatic capacity value - Google Patents

Abstract

PURPOSE:To prevent the dropout of signals in the stage of high speed searching and the damage of information recording discs of electrostatic capacity change type by making the max. size of the sliding contact surface of a recording stylus to be used in sliding contact with the discs, in the diametral direction of the disc, to 2.5-6 times the width of the recording tracks of the discs. CONSTITUTION:A reproducing stylus which detects the change in electrostatic capacity is formed to a heptagonal shape in a surface 51 in sliding contact with information recording discs as shown in the figure. The sliding contact surfaces 51 are enclosed with an electrode ridgeline 58 and other six ridgelines 59-64, and the spacing W between the lines 61 and 62 is made coincident with the diametral direction of the discs. The length thereof is set within the range of 2.5-6 times the width of the recording tracks of the discs. Between the surface 51 up to a height H, such a projecting part wherein the width W increases slightly to W' is formed of two sets of faces 56, 57 to deal with the abrasion of the surface 51. Even if a cantilever not shown is twisted and the sliding contact surface rises one-sidedly, the spacing from the electrode 32 is maintained small, hence the decrease in the reproducing level is maintained small, whereby the dropout of signals is prevented and the excess charge upon the discs is prevented. Thus, the product suited for high-speed searching is obtained.

Description

[Detailed Description of the Invention] A capacitance value change detection type playback needle (hereinafter simply referred to as playback needle) that can always stably reproduce information signals in a recorded trace of a It was created with the purpose of providing

The information signal is reproduced from a disk having a recording trace formed by the arrangement of concavities and convexities corresponding to the information signal by detecting changes in the capacitance value by the electrode part of the reproduction needle that slides into contact with the disk. There are two types of information signal recording and reproducing methods that have been put into practical use: one uses a disk with a guide groove for the playback stylus, and the other uses a disk that does not have a guide groove for the playback stylus. As is well known, among the two methods mentioned above, the latter method has attracted particular attention because it can easily realize various trino play and random access operations. ing.

Now, in an information signal reproducing device that uses a reproducing stylus to read out information signals from a disk, the ambidextrous stylus moves at high speed in the radial direction of the disk during high-speed search mode, rankings, and access operations. It is necessary that the disk be in sliding contact with the disk surface in such a manner that the information signal in the recorded trace can be read out while being moved.

Figures 1 to 4 show the problems of the information signal reproducing device.
FIG. 1 is a plan view showing the relative relationship between the disk 1, the carriage 2, and the planer 1 and the flange 3; FIG. Figure 2 is a perspective view showing the disc 1 and the force/tilt lever 3, and Figure 3 is a perspective view showing the regeneration needle 6 and the disc 1.
and FIG. 4 is a perspective view of a conventional regenerated needle.

When the information signal reproducing device is in the high-speed search mode, the information signal is searched in the radial direction of the disk 1 (in the direction of arrow 4) from the outer circumference to the inner circumference, or from the inner circumference to the outer circumference, at regular time intervals. As the carriage 2 is moved intermittently by a fixed distance, the tracking control system is used to perform tracking control so that the signal is reproduced while accurately following the recording trace on the disk L. The regeneration needle 6, which is fixed to the cantilever 3 (pickup 7-m 3) and VC, is driven and displaced by the drive mechanism (actuator) K of the system, and can be freely displaced between under tracking control and when the tracking control is deviated. The carriage 2 is displaced in the direction of the arrow 5 in the figure in correspondence with the amount of movement of the carriage 2 while repeating two operating states, and a portion of the information signal on the disk 1 is intermittently tracked under tracking control. Disc 1
The recorded self-answers can be searched at high speed, but the sliding contact between the reproducing needle fixed to the cantilever 3 and the disk 1 during the reproducing operation in the high-speed search mode as described above is different from that of the reproducing needle. At least a portion of the sliding surface 7 of the playback needle 6 becomes separated from the surface of the disk 1, and the surface of the disk 10 may be damaged by the corner of the sliding surface of the playback needle 6.

The above points will be explained in more detail as follows.

The cantilever 3 to which the regenerated needle 6 is fixed has its base supported by a support member 10 made of an elastic body, as illustrated in FIG. A magnet 11 provided in the
Drive displacement in the tracking control direction shown by arrow 14 in the figure and knock correction control shown by arrow 15 in the figure due to the electromagnetic force between the coil and the magnetic field generated when a current is passed through a coil (not shown) Drive displacement in the direction and drive displacement in the stylus pressure application direction shown by arrow 16 in the figure are performed. And the above-mentioned support member 1
0 is engaged with a holding member 13vC fixed to the carriage 2.

Therefore, the three forces indicated by arrows 14 to 16 in the figure are always acting on the supporting member 10 during the reproduction operation, and the three forces mentioned above are based on the radial direction of the recorded traces on the disk. The dynamic vibration state of the planer 1/bar 3 is extremely complex because the trunking reference signal is detected and changes moment by moment according to the amount of distortion in the direction of surface runout of the disk.

When the cantilever 3 supported by the support member 10 made of an elastic body as described above operates in the high-speed search mode as described above, that is, when the regeneration needle 6 is under tracking control and when the tracking control When the carriage 2 is displaced in the direction of the arrow 5 in Fig. 1 in a manner that corresponds to the amount of movement of the carriage 2 while repeating two operating states: one in which it is dislocated and freely displaced, the regeneration Because the amount of movement of the needle 6 on the disk surface and the amount of movement of the carriage 2 deviate, the support member 10 is twisted as shown by the arrow 17 in FIG. As shown in FIG. 3, the sliding surface 7 of the playback needle 6 and the surface 22 of the disk 1 are in poor sliding contact.

That is, when the supporting member 10 is not twisted, the regenerating needle 6 aligns its sliding surface 7 with the surface of the disk 10 so that the axis t of the regenerating needle 6 and the normal line 22a of the disk 1 coincide. However, if the support member 10 is twisted, the axis of the regenerated needle 60 and the normal line 2 of the disk 10 will be in perfect sliding contact.
2a, an inclination angle (torsion angle) of θ occurs. As a result, a gap having a size represented by δ given by the following equation is created between the end 23 of the electrode 6 and the surface of the disk 10.

δ Ki w tan θ (where θ is the inclination angle and W is the maximum width dimension of the sliding surface 7 of the regenerated needle 6) The above-mentioned inclination angle (twist angle) θ is the mechanical Therefore, the gap δ is actually determined depending on the characteristics of the regenerated needle 6.
It may be proportional to the maximum width dimension of the sliding surface 7.

Now, in the capacitance value change detection type recording/reproducing method,
Signal 1 Novel C of the playback signal played from the disc is
As is well known, it depends on the gap (gap δ) between the disk 1 and the electrode end 23 of the playback 'tI6.
Electrode end 2 of the regeneration needle 6 when the regeneration needle 6 is tilted
3 and the surface of the disk 10 is proportional to the maximum width W of the sliding surface 7 of the playback needle 6, the signal 1 novel C of the playback signal from the playback needle 6 is The larger the width W of the sliding surface 7 of the regenerating needle 6, the smaller the width becomes.If the maximum width W of the sliding surface 7 of the regenerating needle 6 exceeds a certain limit, the S/N of the tracking reference signal will deteriorate. As a result, the tracking control is deviated, the reproducing needle 6 moves by itself in the radial direction of the disk l, the information signal from the recorded trace is no longer reproduced, and the support member 1o of the cantilever 3 is also subjected to torsional vibration. This may cause damage to the surface of the disc 1 due to the corners of the sliding surface of the playback needle 6.

FIG. 4 is a perspective view of the vicinity of the sliding surface of the regenerated needle 6 showing an example of the configuration of a typical conventional regenerated needle.
In the figure, 7 is a sliding contact surface, 32 is an electrode surface, 33 to 36 are planes that define the outer shape of the regenerated needle 6, 37 is a ridgeline between surfaces 33 and 35, and 38 is a surface. This is the ridgeline between 34 and surface 36.

Since the surfaces 33 to 36 described above are each formed by polishing, the limit value of the relative angular displacement relationship of each surface is naturally determined from the viewpoint of ease of polishing. For example, when the constituent material of the regenerated needle body is diamond, the relative angular relationship of each surface is subject to significant restrictions, especially because the dependence on the crystal orientation of diamond during polishing is strong. Ridgeline 37.3
The opening angle β of the electrode 8 is approximately 60 degrees, and the opening angle α of the electrode is approximately 5 Hikone degrees. Note that the arrow 39 in FIG. 4 indicates the sliding surface 7.
The direction of relative movement between the surface of the disk and the surface of the disk 10 is shown.

In the conventional regenerated needle 6 shown in FIG. 4, its sliding surface 7
The maximum width (diagonal length) W of the VC is initially set at a range that does not interfere with playback, for example, about 57+m, but the sliding surface will gradually wear out with use. Accordingly, the diagonal length W gradually increases.

Therefore, in the case of a regenerated stylus whose diagonal length W is the initial value of 5 μm and a regenerated stylus whose diagonal length W is 9 μm due to wear of the regenerated stylus 6, the outer periphery of the disk 1 is When we conducted a round-trip regeneration experiment from the inner station to the outer circumference using five regenerated needles each, we found that the maximum width dimension (diagonal length) W at the sliding contact surface 7 was 5 μm.
With the regenerated needle, there is no signal dropout, whereas with the regenerated needle with the maximum width dimension (diagonal length) W at the sliding surface 7vc of 9 μm, signal dropout occurs 2.3 times on average. However, according to the above experimental results, when the information signal was reproduced from disk 1 in high-speed search mode using a reproducing stylus with the maximum width W of the sliding surface of 5 μm, there was no signal loss. The fact that when the information signal is reproduced from the disc 1 in the high-speed search mode using the reproduction device 1 in which the maximum width dimension W of the sliding contact surface is 9 μm, there will be a signal dropout in the reproduction signal is already mentioned. As shown in FIG. 3, the sliding surface 7 of the reproduction needle 6 rises as shown in FIG. Maximum width dimension W of sliding surface 7 of regenerated needle 6
This is thought to be due to the increase due to the increase in size.

Therefore, a regenerated needle having an external shape as shown in FIG.
Its maximum width (diagonal length) W at the sliding surface 7vC is
It can be said that the lifespan of the regenerated needle reaches its end before it wears down to 9 μm. Conventionally, for this type of regenerated needle, the electrode width We has a specific dimensional relationship with the recorded trace width dimension. It is clear that in addition to the restrictions on the lifespan of recycled needles, which had been said to be usable until the end of the term, the maximum width of the sliding contact surface must also be considered as a condition for determining the lifespan of recycled needles. It became.

In the conventional regenerated needle shown in FIG. 4, since the apex portion 40.41 exists on the sliding surface 7, when torsional vibration of the support portion of the cantilever 3 -q'toVC occurs. Furthermore, when the apex portions 40, 41 of the sliding surface 7 hit the surface of the disk 1, a large stress concentration occurs on the surface of the disk 10, resulting in damage to the surface of the disk 10.

The present invention has been made for the purpose of providing a regenerated needle that can satisfactorily solve the various problems of conventional regenerated needles as described above. The macroscopic contents of the change-detecting birth needle blade will be explained in detail with reference to the attached drawings.

FIG. 5 is an oblique view 1 of a main part of an embodiment of the amphiphilic needle of the present invention, and in this FIG. and six other ridge lines 49-64, forming a heptagonal shape. Sliding surface 51vC Distance W between ridgeline 61 and ridgeline 62
That is, 1] dimension W of the portion showing the maximum width in the direction perpendicular to the direction of relative movement between the playback needle and the disk.
is within the range of 25 to 6 times the recording trace d] of the main information signal on the disc 1, and the width W is perpendicular to the sliding surface 51. The height is approximately constant within a predetermined height H range in the direction shown in FIG.

In Fig. 5, the width dimension of the part showing the maximum width of the sliding contact surface 51VC is designated as W, and the width dimension of the portion at the height H from the sliding contact surface 51 is designated as WI due to processing limitations. This is because WI is slightly larger than W.

The electrode surface 32, surfaces 33 to 36, etc. in FIG. 5 are surfaces for forming the general outer shape of the regenerated needle in the same manner as on the regenerated needle shown in FIG. 4. Also, 56. in FIG.
Reference numeral 57 denotes a processed surface for forming the tip of the regenerated needle as described above, and this processed surface is similarly formed at approximately symmetrical positions on the left and right sides of the regenerated needle, so that the tip of the regenerated needle is shaped as described above. The height H from the sliding surface 51 has approximately the same maximum width W.

In the reproducing needle of the present invention, the dimension W of the portion showing the maximum width in the direction orthogonal to the direction in which the sliding surface 51 moves relative to the disk is defined as the width of the recording trace of the main information signal on the disc. The reason why the range was selected from 2.5 times to 6 times is as follows.

First, the upper limit value of the width W of the portion of the sliding contact surface 51 that indicates the maximum width is set to a width that does not cause signal loss in the reproduced signal even when regenerating noodles in high-speed search mode. It is something that should be done. That is,
The cause of signal loss in the reproduced signal in the above reproduction state is that the sliding surface of the reproduction needle is inclined due to the twisting of the support member 10, as described above, and the gap between the surface of the disk 1 and the electrode end 23 is This is because the gap δ that occurs becomes larger, and the tracking reference signal cannot be extracted and the reproduction @ number cannot be asked.As a result of the experiment, the width of the recorded trace due to the main information signal can be reduced to W. It has been confirmed that the maximum width dimension of the sliding contact surface that can provide a state in which no signal dropout occurs in the reproduced signal in the high-speed search mode is 6Tw. This means that if the recording trace width W is 135 μm, the maximum width of the sliding surface of the reproduction needle should be selected to be 85 μm or less.

Further, the lower limit of the maximum width of the sliding surface of the reproducing stylus is restricted by the magnitude of the load that the sliding surface of the reproducing stylus applies to the disk surface. In other words, when the playback stylus is in sliding contact with the disk surface, if the area of the sliding surface is small, stress concentration will occur on the disk, damaging the disk and shortening the life of the disk. If the maximum width dimension W is reduced so that the area of the sliding surface becomes less than the allowable limit, damage to the disk surface becomes significant, for example, in still image playback mode.

According to the results of experiments, it has been revealed that the lower limit of the maximum width of the sliding contact surface of the reproduction stylus is 25 times the recording trace width W of the recording trace of the main information signal on the disc. This means that if the recorded trace rllTw is 135 μm, the maximum width of the sliding surface of the reproduction needle should be selected to be 35 μm or more.

6 to 9 are perspective views of other embodiments of the present invention σ)+11 raw needle). First, in FIG. An electrode 62 having a constant width is formed on this plane 61. 63 and 64 in FIG. 6 are the polished surfaces of the slack, and the surface 61
The arbitrary cross-sectional shape of the part surrounded by the three faces of -63 is triangular as shown by the two-dot chain line 65, and the general outer shape of the regenerated needle body is a triangular inscription overall. .

In the regenerating needle shown in FIG. 6, surfaces 66.
67 is formed by polishing and removing it to a predetermined height H, so that the largest middle part of the sliding surface 60 is formed to have a width W and a predetermined height H. In FIG. 6, the width Wl may be slightly larger than the width W. The width dimension W of the maximum middle part of the sliding contact surface is 2.5 for the medium fineness of the record trace.
It goes without saying that the relationship Tw≦W≦6Tw should be satisfied, and this point also applies to the following embodiments.

FIG. 7 is a perspective view of the present invention applied to a regenerated needle having a trapezoidal outer shape. In FIG. It is said to be W in the middle. 71 is an electrode, and 72 is a line indicating that the regenerated needle body has a trapezoidal cross section. Moreover, surfaces 76 and 77 are surfaces formed by polishing. In addition,
The surface 57 in FIG. 5, the surface portion 67 in FIG. 6, and the surface 77 in FIG. 7 need not be formed parallel to the sliding surface.

Further, FIG. 8 shows an embodiment in which the regenerated needle main body has a cylindrical outer shape, and is an example of a configuration in which the sliding surface 81 is surrounded by seven surfaces 82 to 87 to determine the shape. Furthermore, the regenerated needle shown in FIG. 9 has a configuration in which the regenerated needle shown in FIG. 5 is changed to have one curved surface 92, which corresponds to the rear surfaces 56 and 57. In FIG. 9, 93 is an electrode.

In the regenerated needles shown in FIGS. 8 and 9, as the regenerated needles are worn out through use, the width II]W of the portion having the maximum width on the sliding contact surface gradually increases, but the width W The minimum value Wm1n and rl] The maximum value W max of W
However, even though we have already mentioned the medium fineness of the recorded trace, good reproducing operation can be performed until the width dimension of the maximum middle part of the sliding contact surface reaches Wmax, and compared to the conventional reproducing needle. Of course, a regenerated needle with a long life can be obtained.

As is clear from the detailed explanation above, the regenerated needle of the present invention has a width W of the portion having the maximum width on the sliding surface, even when the regenerated needle is operated in the high-speed search mode. The dimensions are within the range that will not cause any signal loss in the signal, and the dimensions are within the n range so that no excessive load is applied to the disc, so there is no risk of damaging the disc during playback or damaging the playback signal. There is no signal loss, and the width of the regenerated needle remains approximately constant within a predetermined range even when the regenerated needle is worn, so the life of the regenerated needle can be determined only by the electrode width. Furthermore, even if torsional vibration occurs in the support member 10 of the cantilever 3, stress is applied to the disk at the ridgeline on the sliding surface of the regeneration needle, so that the top of the cantilever 3 does not move like the conventional regeneration needle. This has advantages such as significantly less damage to the disk than when stress is applied to the disk at the corners.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a part of the reproducing device, FIG. 2 is a perspective view showing a disk and a cantilever, FIG. 3 is a front view of a reproducing needle and a disk, and FIG. 4 is a part of a conventional reproducing needle. A perspective view of
5 to 9 are perspective views of a portion of an embodiment of the regenerated needle container of the present invention.

Claims (1)

[Claims] An information recording medium disc having a recording trace formed by arranging unevenness corresponding to the information signal.The information signal in the recording trace is brought into sliding contact with the recording trace, and the amount of electricity changes according to the change in capacitance value. The playback needle is a change-detecting capacitance value change-detecting playback needle that is equipped with an electrode part that can be taken out as a slider, and serves as a sliding surface that slides into contact with the information recording medium disk. The width of the portion showing the maximum width in the direction perpendicular to the direction of movement is within the range of 25 to 6 times the width of the recording trace of the main information signal on the information recording medium disc. , and the shape and dimensions are such that the portion exhibiting the maximum width has a substantially uniform width within a predetermined length range in a direction perpendicular to the width direction, and includes a sliding contact surface. Regeneration needle that detects changes in capacitance value