KR940003649B1 - Magnetic assembly - Google Patents

Abstract

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Description

Magnetic head assembly

1 and 2 illustrate a conventional mechanical system including a magnetic head assembly designed to avoid resonance.

3A to 3C are a plan view, a front view and a side view respectively showing an embodiment of the magnetic head assembly of the present invention.

4A and 4B show an example of a magnetic disk on which information signals are recorded and reproduced.

5a and b are graphs showing the results of experiments for performance evaluation of the magnetic head assembly of the present invention on a 3.5 inch diameter standardized magnetic disk.

6a and b are graphs similar to FIGS. 5a and b for a 5 inch diameter standardized magnetic disk.

7 (a) to 7 (c) show vibrations of the magnetic head assembly due to stick slip between the magnetic head assembly and the magnetic disk.

8A to 8D show changes in the relative speed between the magnetic head assembly and the magnetic disk due to stick slip of the magnetic head assembly, and changes in recording and playback characteristics due to the speed change.

* Explanation of symbols for main parts of the drawings

1,13: magnetic head assembly 2: gimbal support means

3,6 absorber 4: metal plate member

7: rotating arm 8,8 ′: magnetic disk

9: lower magnetic head assembly 10: leaf spring

14: slide surface 15: magnetic core

16: Slide Body 17: Home

18: opening

The present invention is part of US Patent Application No. 273,892, filed November 21, 1988.

FIELD OF THE INVENTION The present invention generally relates to a magnetic head of a magnetic recording / reproducing apparatus for recording and / or reproducing information signals on and from a rotating magnetic disk, in particular recording of a magnetic recording / reproducing apparatus. And / or a mechanical disk assembly capable of avoiding mechanical vibrations associated with the rotation of the rotating magnetic disk during playback.

In general, a flexible magnetic disk, commonly referred to as a floppy disk, is recorded or reproduced by a magnetic recording / reproducing apparatus including a magnetic head arranged to contact the upper and / or lower surfaces of the magnetic disk. The magnetic head is in close contact with the surface of the magnetic disk and magnetizes the magnetic material stacked on the surface of the magnetic disk according to the information signal or forms an electrical signal based on the magnetization of the magnetic disk.

In such a magnetic recording / reproducing apparatus, it is essential to maintain proper contact between the magnetic disk and the magnetic head in order to achieve proper satisfactory recording and / or reproduction. Thus, the magnetic head is supported by a resilient mechanical system that elastically adheres the magnetic head to the surface of the magnetic disk. However, such a resilient mechanical system tends to produce a large mechanical resonance when the vibration frequency of the magnetic head matches the resonance frequency of the mechanical system. In such a case, the magnetic head may bounce off the surface of the magnetic disk, cause recording or reproduction to be wrong, or cause information signal dropout.

In the past, various systems have been proposed to avoid resonance of the mechanical system supporting the magnetic head. For example, an elastic member was added to the mechanical system to change the resonance frequency. Alternatively, a low Q vibration absorber was added to the elastic mechanical system. However, the provision of such additional elastic members in the mechanical system increases the size of the mechanical system and consequently makes the magnetic recording / reproducing apparatus large. In addition, the manufacturing cost of the magnetic recording / reproducing apparatus has been increased. On the other hand, when a low Q material is added to the mechanical system, the reaction of the mechanical system following the displacement or deformation of the magnetic disk becomes unacceptably slow and the magnetic head cannot maintain proper contact with the magnetic disk. This in turn causes contact loss between the magnetic head and the magnetic disk, resulting in poor recording or reproduction of the information signal.

It is therefore a general object of the present invention to provide a novel and useful magnetic head assembly which eliminates the above mentioned problems.

A still further particular object of the present invention is to provide a magnetic head assembly which is a magnetic recording / reproducing apparatus for recording and / or reproducing an information signal on and from a magnetic disk included in a hard cartridge, wherein the cartridge is magnetic. The head assembly has a window having a length (m) of about 9 mm in the direction of rotation of the disk to bring the head assembly into contact with the magnetic disk, the magnetic head assembly having a slide provided with a magnetic core for recording and / or reproducing the information signal. The body includes a body, wherein the slide surface is selected such that the length (B) of the slide surface in the rotational direction of the magnetic disk and the width (A) of the slide surface in the radial direction of the magnetic disk satisfy B≥4 and the length (B). ) Is defined on the slide body in contact with the surface of the magnetic disk in such a configuration that satisfies 0.45 m? B? 0.55 m. According to the present invention, the vibration of the magnetic head assembly can be particularly avoided in the case of a so-called 3.5 inch flexible magnetic disk included in the hard cartridge without deteriorating the following reaction of the magnetic head assembly following the displacement or deformation of the magnetic disk. Will be. In other words, the present invention realizes a simple magnetic head assembly in which the mechanical system for supporting the magnetic head exhibits stable recording and reproducing performance without adding a special member.

Other objects and further features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.

FIG. 1 shows an example of a conventional mechanical system 12 used to support a magnetic head assembly of a magnetic recording / reproducing apparatus having a structure for avoiding mechanical resonance of the mechanical system. Typically, the magnetic head assembly includes a slide body and a magnetic core (not shown) supported by the slide body. In the figure, the flexible magnetic disk 8 is connected to a rotating arm 7 rotatably supported by the carriage 10 via the lower magnetic head assembly 9 mounted on the cartridge 100 and the leaf spring 10. It is held between the upper magnetic head assemblies 1 supported by it. The upper magnetic head 1 is mounted to the rotating arm 7 via an elastic gimbal support means 2 such that the magnetic head assembly 1 can be tilted about two mutually perpendicular axes. One of the two mutually perpendicular axes extends in the radial direction of the magnetic disk 8 and the other extends in the rotational direction of the magnetic disk 8. Thus, the magnetic head assembly 1 can follow the displacement or deformation of the magnetic disk 8 when the disk 8 is rotated.

The system 12 constitutes a resonant system since the mechanical system of FIG. 1 includes a spring 10 and a gimbal support means 2 which are elastic members as well as a rotary arm 7 which is a movable member. Thus, there is a substantial risk that the magnetic head assembly 1 will bounce off the magnetic disk 8 when the magnetic head assembly 1 is vibrated and a resonance is established between the mechanical system 12 and the magnetic head assembly 1. If such resonance occurs, the magnetic head assembly may be detached from the surface of the magnetic disk 8 and recording and / or reproduction may be poor, or the recorded signal or the reproduced signal may be dropped.

In order to remove such a magnetic head, the conventional mechanical system shown in FIG. 1 uses an additional metal plate member 4 having a suitable size. The metal plate member 4 is mounted on the gimbal support means 2 via a vibration absorber such as rubber or sponge having a low Q value to change the natural frequency of the mechanical system and absorb vibration energy. Another conventional system uses an absorber 6 made of silicone rubber or the like having a low Q value. This absorber 6 is attached to the gimbal support means 2 as shown in FIG. 2 in order to reduce the vibration of the magnetic head 1 supported by the gimbal support means 2.

However, although these systems are successful in suppressing the occurrence of resonance, the use of the mechanical system 12 shown in FIG. 1, which includes the absorber 3 and the metal plate 4, reduces the size of the magnetic recording / reproducing apparatus. Increase the height of the system 12 as opposed to the requirement for it. Moreover, the use of such additional parts results in an increase in the manufacturing cost of the magnetic recording / reproducing apparatus. In the system shown in FIG. 2 in which the absorber 6 is mounted on the gimbal support means 2, the following reaction of the magnetic head assembly 1 following the displacement or deformation of the magnetic disk during the operation of the magnetic recording / reproducing apparatus is performed. It may worsen, and in some cases, no contact may be made between the magnetic head assembly 1 and the magnetic disk 8.

An embodiment of the magnetic head assembly of the present invention will now be described with reference to FIGS. 3A-C. In FIG. 3A, the magnetic head assembly 13 of the present embodiment includes a ceramic slide body 16 defined by a flat slide surface 14, which flat slide surface 14 includes a magnetic disk 16. This flat slide surface 14 is suitable for contact with a magnetic disk (not shown). As can be seen from the figure, the slide surface 14 extends in the direction of rotation of the magnetic disk and in the direction of rotation of the magnetic disk in contact with the slide surface 14 as clearly shown in FIG. 3C. The groove 17 is divided into a first slide surface portion 4a and a second slide surface portion 4b. Therefore, the air trapped between the magnetic head assembly and the surface of the magnetic disk can escape, so that no air film is formed between the magnetic disk and the magnetic head assembly. The first and second slide surface portions 14a and 14b are configured to have the same shape, and one of them 14a is inserted with a magnetic core 15 extending in the rotational direction of the disk. The magnetic core 15 is made of ferrite and includes a read / write core 15a and a pair of erase cores 15b and 15c which are used to record and / or reproduce an information signal. In this embodiment, the size of the slide surface portion 14a measured in the radial direction of the disk, referred to later as width and indicated by reference A in FIG. 3A, is the size of the core 15 measured in the radial direction of the magnetic disk. It is selected at least twice the width W of the core 15.

By setting the width A to at least twice the width W, the surface of the magnetic core 15 is easily flattened or finished so that the surface of the core 15 is flush with the flat slide surface 14. . Thus, the surface of the magnetic core 15 becomes flat, and very good contact is achieved between the entire surface of the magnetic core 15 and the magnetic disk.

In the magnetic head assembly as shown in Figs. 3A to 3C, the slide surface 14 is properly constructed and cleaned so that the vibration of the magnetic head assembly can be reduced without providing additional members for use in the conventional magnetic head assembly. I found it successfully suppressed.

More specifically, the dimension B (Fig. 3a) of the slide surface 14, which is measured in the rotational direction of the magnetic disk and is subsequently referred to as length, and the width A of the slide surface 14 described above, Is a currently used standardized flexible magnetic disk that is accommodated in a soft jacket, by selecting B / A to be larger than 5, i.e., B / A > Magnetic head assembly 13 by selecting B / A to be greater than about 4, i.e., B / A > 4, if the magnetic disk is a currently used 3.5 inch diameter standardized soluble magnetic disk housed in a hard cartridge. It has been found that the mechanical vibration of is effectively suppressed. In other words, the resonant vibration of the magnetic head assembly 13 can be suppressed when B / A satisfies B / A ≧ 5 or B / A ≧ 4 depending on the type of magnetic disk.

On the other hand, the upper limit of the B / A is determined by various factors such as the contact state between the magnetic head assembly and the magnetic head, the curvature or radius of the recording track on the magnetic disk, the total size of the magnetic recording / reproducing apparatus, and the like. In general, the above factors are set such that the maximum value of the B / A ratio is considered to be less than about 6 in consideration. Thus, the preferred range of B / A is limited to 5 ≦ B / A ≦ 6 for 5 inch diameter discs and 4 ≦ B / A ≦ 6 for 3.5 inch diameter discs.

It has also been found that the slide surface portion 14a, which at the same time includes the magnetic core 15 and the slide surface portion 14b, must be finished with extremely precise flatness. Preferably, the slide surface 14 is finished to a mirror-like shine. For example, the first slide surface portion 14a and the second slide surface portion 14b are finished to have a precision such that the difference between the maximum value of the peak on the surface and the minimum value of the valley portion is smaller than about 0.3 mu m. The roughness of the surface is checked using an optical plane under monochromatic light with a wavelength in the range of 5900 Hz-6000 Hz.

Further, the length B of the slide surface 14 represents the total length of the magnetic core 15 including the read / write core 15a and the erase cores 15b and 15c and extending in the rotational direction of the magnetic disk. In the present invention, in the case of the 3.5-inch flexible magnetic disk that is commonly used, the jacket or cartridge (4a, 4b) of the magnetic disk to permit contact between the magnetic disk of the jacket and the magnetic head assembly located outside of the jacket. It has been found that suppression of resonance is most effective when the length B is set to about 45% to 55% of the length m, which is the width of the opening 18 provided in FIG. Therefore, in the case where the magnetic disk is a 3.5 inch flexible magnetic disk accommodated in a hard cartridge, resonance is most satisfactorily suppressed when 0.45 ≦ B ≦ 0.55 mm is satisfied. It has been found that for a 5 inch diameter magnetic disk housed in a soft jacket, 0.35 m < B < 0.45 is preferred, as described in US Patent Application No. 273,892.

Now, experiments will be described that are attempted by the applicant of the present invention and form the basis of the present invention.

Figures 5a and b show the results of experiments attempted by the applicant and are intended to evaluate the performance of the magnetic head assembly of the present invention. Therein, a so-called 3.5 inch standard soluble magnetic disk housed in a hard cartridge is used as a medium for recording a test signal. Since the magnetic disk used was a standardized 3.5-inch disk, the opening 18 formed in the hard cartridge had a standard length m set to 9 mm +/- 0.20 mm.

Throughout the entire experiment, the magnetic head assembly used had a slide surface 14 with a width A set to 0.75 mm, and the slide body 16 forming the magnetic head assembly was 2.7 mm +/- 0.05 mm. It had a height H (FIG. 3C) measured perpendicular to the slide surface A that was set. In this experiment, the measurements were made using different magnetic head assemblies with different lengths (B) and the modulation of the reproduced test signal, ie the change in amplitude of the reproduced test signal from the disc and the percentage of occurrence of dropout of the reproduced test signal. Was made for. Of course, the test signal was recorded on the disc with constant amplitude.

The modulation in FIG. 5A is defined as the ratio of the minimum amplitude of the reproduced test signal divided by the maximum amplitude of the reproduced test signal.

In FIG. 5A, the modulation is represented as a function of parameter B / m. It can be seen that the modulation is in the range of about 0.45 to 0.55, with particular preference being given in this range to be generally flat and close to one. On the other hand, Figure 5b shows the percentage of dropout of the test signal being reproduced as a result of resonance as a function of parameter B / A. And when parameter B / A is set greater than about 4, the drop-off is reduced to zero in general.

On the other hand, Figures 6a and b show the results of the same experiment for a 5 inch diameter magnetic disk housed in a soft jacket. In this case, a range larger than about 5 is preferred for parameter B / A (B / A ≧ 5) while a range of 0.35 to 0.45 is preferred for parameter B / m (0.35 ≦ B / m ≦ 0.45). You can see that. Thus, the results of the experiments in FIGS. 6a and b are consistent with the description of US Patent Application No. 273,892, which is a parent application, and in fact form the basis of this patent application.

The reason why the vibration is suppressed by the above-described configuration of the magnetic head assembly 13 is not fully understood. According to the applicant's experiment, virtually no resonances were observed when set larger than B / A 5 and the slide surface portions 14a, 14b were finished in a plane with the precision as already described. On the other hand, if the length B is increased and the B / A exceeds 6, the length B of the slide surface 14 becomes too long to maintain proper contact between the soluble disk and the slide surface through the entire length of the slide surface. It becomes difficult to do. In addition, the magnetic head assembly 13 having such a configuration is likely to cause resonance when the B / A increases beyond the above-mentioned range. Further, the increase in the length B becomes undesirable in view of increasing the dimensions of the magnetic head assembly and reducing the size of the magnetic recording / reproducing apparatus.

On the other hand, if the B / A is reduced below about 5, there is a risk of stick slip between the magnetic head assembly 13 and the magnetic disk to cause mechanical vibration of the magnetic head assembly. Hereinafter, the mechanical vibration of the magnetic head assembly due to the stick slip will be described with reference to FIGS. 7A to 7C. FIG. 7A shows a state in which the magnetic head assembly 13 is normally engaged with the magnetic disk 8 'in such a manner that the slide surface 14 is in parallel contact with the magnetic disk 8'. In this state, the entire surface of the slide surface 14 is in contact with the magnetic disk 8 '.

On the other hand, (b) of FIG. 7 shows a state in which the magnetic head assembly 13 is inclined due to stick slip on the magnetic disk. As shown in FIG. 7B, when the stick slip phenomenon occurs, the magnetic head assembly 13 is caused by the magnetic disk as a result of the frictional force between the slide surface 14 of the magnetic head assembly 13 and the magnetic disk 8 '. It is pushed in the rotational direction of the magnetic disk 8 '. Since the magnetic head assembly 13 is prevented from moving with the rotation of the magnetic disk by a carriage (not shown) similar to the carriage 100 of FIG. 1, the magnetic head assembly 13 is caused by frictional force. As a result of the arrangement, as shown in FIG. 7 (b), it tends to rotate or incline with respect to its front end 13 'while opposing the rotation moment of the magnetic disk 8'. Such tendency is enhanced by a decrease in length B or a decrease in B / A. When the inclination reaches the critical angle, the frictional engagement between the magnetic head assembly and the disk is achieved in a mechanical system comprising a gimbal plate (not shown in Figures 7a to 7c) that supports the magnetic head assembly. It is overcome by the counteracting moment provided by it. This counteracting moment acts on the magnetic head assembly to recover the initial state shown in (a) of FIG. 7, wherein the magnetic head assembly 13 has a slide surface 14 parallel to the magnetic disk 8 ′. It returns to a state rapidly. This state is shown in Fig. 7C, and the magnetic head 13 instantaneously loses its contact with the magnetic disk as shown in the figure. Then, the magnetic head assembly 13 recovers its contact with the magnetic disk 8 'again and returns to the initial state shown in Fig. 7A.

Therefore, the order of the states shown in Figs. 7A to 7C is repeated, and the magnetic head assembly 13 vibrates. The vibration of such a magnetic head assembly causes a periodic change in the speed of the magnetic head assembly 13 with respect to the rotational speed of the magnetic disk 8 'as shown in FIG. 8A. Figure 8b shows such periodic velocity changes in an enlarged state. In FIG. 8B, the dotted down line portion corresponds to a transient state in which the state of the magnetic head assembly changes from the state of FIG. 7A to the state of FIG. 7B. On the other hand, the rising line portion indicated by a vacant circle in FIG. 8B corresponds to a transient state in which the state of the magnetic head assembly 13 changes from the state of FIG. 7B to the state of FIG. 7C. As a result of the repetition of the state of Figs. 7A to 7C, a small wave appears in the magnetic disk 8 'at the relative speed of the magnetic head assembly 13. The flat line portion in Fig. 8B shows a state in which no stick slip occurs.

When stick slip occurs, the magnetic head assembly instantaneously loses contact with the magnetic disk, and as a result, the output voltage V of the magnetic head assembly oscillates as illustrated schematically in FIG. 8C. As a result, a significant amount of jitter appears in the output voltage signal shown in FIG. 8D in addition to the wave of the output voltage. The normal output signal is shown in solid lines in FIG. 8d.

As already explained, the vibration of the magnetic head assembly 13 due to stick slip is caused by making B / A greater than or equal to 4 for a 3.5 inch flexible magnetic disk, and at the same time by very precise finishing of the slide surface. Can be prevented. By setting B / A greater than 4, the reaction moment provided by the mechanical system is increased and the magnetic head assembly is more effectively returned to its original state. In addition, by glazing the slide surface, the coefficient of friction, which is the cause of stick slip, can be reduced.

Thus, by selecting B / A as described, the magnetic head assembly does not cause vibration, and stable recording and reproduction can be achieved.

The present invention is not limited to the magnetic head assembly for recording and / or reproducing the information signal on the double-sided magnetic disk as described, but is also applicable to the magnetic head assembly for recording and / or reproducing the information signal on one magnetic disk. .

In addition, the present invention is not limited to the above embodiments, and various changes can be made outside the spirit of the present invention.

Claims (1)

A window having a standard length (m) of about 9 mm in the direction of rotation of the flexible magnetic disk is formed and received in a cartridge having a greater rigidity than the flexible magnetic disk which allows the magnetic head assembly to contact the flexible magnetic disk, A magnetic head assembly for recording and / or reproducing information signals from and on a flexible magnetic disk having a 3.5 inch standard diameter, the base comprising: a base, a slide surface defined on the base for contact with the flexible magnetic disk, And a magnetic core inserted into the slide surface, the slide surface having a length B of the slide surface which is a dimension of the slide surface in the longitudinal direction of the slide surface and a dimension of the lateral slide surface perpendicular to the longitudinal direction. The width A of the in-slide surface satisfies the rotational direction of the flexible magnetic disk in such a configuration that B / A > Extending in the longitudinal direction, the slide surface is finished very precisely such that the surface roughness of the slide surface is substantially smaller than the surface roughness of the recording surface of the flexible magnetic disk on which the information signal is recorded, and the length B Magnetic head assembly, characterized in that it is set to satisfy 0.45≤B≤0.55m.

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