JPH04178920A - Protrusion detection head assembly - Google Patents

Abstract

PURPOSE:To obtain a protrusion signal with an improved sensitivity by mounting a piezo element with the natural frequency which is equal to that of a gimbal bar to a support arm. CONSTITUTION:A ceramic core 3a' vibrates due to collision of a magnetic disk and a protrusion and the natural vibration of a frequency fO of a gimbal bar 3b' which is generated by the vibration of the ceramic core 3a' is transmit ted to a piezo element 6' of the natural frequency fO which is mounted to a support arm 4 elastically. Then, regardless of an extremely low natural fre quency of the support arm 4 due to rigidity, the piezo element 6' resonates being induced by the natural vibration of the gimbal bar 3b' due to mutual resonance operation and then a protrusion signal with a sufficient strength is output from a protrusion detection circuit 7, thus obtaining a protrusion signal with an improved sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a seven-door assembly for detecting protrusions used in a protrusion inspection device for magnetic disks.

[Prior Art] A hard magnetic disk used in an information processing device is based on an aluminum disk, and a magnetic film is formed on the surface of the disk by coating, sputtering, or the like. It is necessary for the magnetic film to have a smooth surface with no irregularities, and polishing is performed for this purpose. However, even after polishing, protrusions may remain, and if the protrusions remain, there is a risk or disadvantage that the magnetic head may collide and be damaged, or errors may occur in data. In order to avoid this, a protrusion inspection is performed following polishing, and depending on the results, either re-polishing is performed or the polishing is terminated.

FIG. 2(a) shows an outline of a magnetic disk protrusion inspection apparatus, FIG. 2(b) shows a conventional protrusion detection assembly, and FIG. 2(c) shows a waveform of a protrusion signal. In Figure (a), a magnetic disk 1 to be inspected is mounted on a spindle 2 and rotates. On the other hand, the head assembly 3 has a helad core 3a made of ceramic, metal, etc. attached to the tip of a gimbal t<-3b, and a piezo element 6 is fixed at an appropriate position on the head core 3a, as shown in FIG. A protrusion detection head assembly is configured. The other end of the gimbal bar 3b is attached to a support arm 4, and the support arm 4 is further fixed to a moving part 5a of a carriage mechanism 5. The moving part 5a is connected to a threaded rod 5c rotated by a drive motor 5b, and the rotation causes the head assembly 3 to move in the radial direction of the magnetic disk, causing the head core 3a to float due to the air flow. If there is a protrusion on the surface of the magnetic disk, the bottom surface of the head core 3b collides with the protrusion, and the piezo element 6 outputs a protrusion signal as shown in FIG. The protrusion signal is input to the protrusion detection circuit 7 through the connection line 6a, and the size and location of the protrusion are inspected.

In recent years, magnetic disks have become smaller and their recording densities have become more sophisticated, and ultra-small and lightweight thin-film heads using ceramic cores have appeared as magnetic heads. Correspondingly, in protrusion inspection as well, it is necessary to use a ceramic core of a thin film head as the head core. However, since the ceramic core is extremely small,
It is difficult to attach the piezo element 6 to this, and it is also difficult because the gimbal bar is also miniaturized. Therefore, the piezo element 6 is necessarily attached to the support arm 4.

[Problems to be Solved] FIG. 3(a) shows a protrusion detection head assembly constructed as described above, in which the ceramic core 3a of the thin film head is
A small and lightweight head assembly 3' is constituted by ' and gimbal bar 3b', the other end of gimbal bar 3' is attached to support arm 4, and piezo element 6 is fixed at an appropriate position on support arm 4. When a protrusion inspection was performed using such a protrusion detection assembly, it was found that the vibration of the ceramic core 3a' caused by the collision with the protrusion was
It is transmitted to the gimbal bar 3b', and the gimbal bar vibrates at its natural frequency. On the other hand, the support arm 4 is an elastic body and is fixed to the movable part 5a in a cantilevered manner, so it can vibrate at 1M, but its natural frequency is very low and the vibration is - It was found that the protrusion signal was not transmitted at all or was so attenuated that the protrusion signal was so weak that the protrusion was not detected in the titration. It is necessary to take effective measures against the above.

Here, although the vibration system of the protrusion detection head assembly described above is somewhat complicated, consider a simplified vibration system model shown in FIG. 3(b). Now, assume that the gimbal bar 3b' is a vibration source Si, and its natural frequency is f.The support arm 4 is an elastic body M with a very low natural frequency, and the gimbal bar 3b' is elastically coupled to this. On the other hand, assume that the piezo element 6 is a vibrated body S2, which is also elastically coupled to the support arm 4. Now, the natural frequency of the vibrated body S2 is equal to the natural frequency of the vibration source St. It is empirically known that when the number is equal to the number to, the vibrated body S2 resonates at the natural frequency fO due to the natural vibration of the vibration source 81, regardless of the very low natural frequency of the elastic body M. By utilizing such mutual resonance between the vibration source Sl and the vibrated body S2, it should be possible to obtain a sufficiently strong protrusion signal.

An object of the present invention is to provide a protrusion detection assembly that can obtain a protrusion signal with good sensitivity by utilizing the above-mentioned mutual resonance phenomenon.

[Means for Solving the Problems] This invention has a small and lightweight head assembly consisting of a protrusion detection head and a gimbal bar to which the protrusion head is fixed at the tip, and the other end of the gimbal bar is connected to the gimbal bar via a support arm. The magnetic disk is attached to a carriage mechanism, and the carriage mechanism moves and floats the protrusion detection head relative to the surface of the rotating magnetic disk, and the piezo element r detects vibrations generated in the head assembly by the protrusions present on the surface. This is a protrusion detection rad assembly used in a disk protrusion inspection device, and is constructed by using a piezo element having a natural frequency equal to the natural frequency of the gimbal bar and elastically attaching it to a support arm.

[In the protrusion detection head assembly having the structure described in 1- above, the vibration generated in the protrusion detection head due to the collision with the protrusion is transmitted to the gimbal bar to which the protrusion detection head is fixed, and the gimbal bar adjusts its own natural frequency. It vibrates. On the other hand, since the piezo element which is elastically attached to the support arm has a natural frequency equal to that of the gimbal bar, the piezo element which is elastically attached to the support arm has a natural frequency equal to that of the gimbal bar. The piezo element resonates due to the natural vibration of the gimbal bar, and a strong protrusion signal is generated.

[Embodiment] FIG. 1 shows an embodiment of a protrusion detection head assembly according to the present invention. As a protrusion detection head, for example, a head assembly 3' is constituted by a ceramic core 3a' of a thin film head and a downsized gimbal bar 3b' having the ceramic core 3a' fixed to the tip thereof. Since the gimbal bar 3b' is light, its resonant frequency fo is quite high, for example, several kHz or more. The other end of the gimbal bar 3b' is attached to the support arm 4 in a conventional manner. The support arm 4 is made of a highly rigid elastic body with a fairly low natural frequency, and as in the past, the moving part 5 of the carriage mechanism
It is fixed in a cantilevered manner to a.

At the illustrated position of the support arm 4, a support rod 6b made of a rubber material or the like having appropriate elasticity is used to elastically support the piezo element 6' so as to facilitate resonance.

The natural frequency of the piezo element 6' is made equal to the natural frequency f of the gimbal bar 3b' due to the mutual resonance effect.

Piezo element r-6' is connected to protrusion detection circuit 7 by connection line 6a. Note that the piezo element 6' having a fixed jf frequency fo of several kHz can be easily manufactured.

With this configuration, the ceramic core 3a' vibrates due to collision with the protrusion of the magnetic disk, and the frequency f of the gimbal bar 3b' is caused by this vibration.

The rigid rf vibrations of are transmitted to the piezo element -r6' of natural frequency t'o which is elastically attached to the support arm 4, and despite the very low natural frequency of the support arm 4 due to the rigidity, the sum Due to the resonance effect, the piezo element 6' resonates due to the natural vibration of the gimbal bar 3b', and a sufficiently strong protrusion signal is output from the protrusion detection circuit 7.

[Effects of the Invention] As is clear from the following explanation, in the protrusion detection assembly according to the present invention, the natural vibration of the gimbal bar caused by the vibration of the protrusion detection head is transmitted to the piezo element elastically attached to the support arm. This causes a piezo element with a natural frequency equal to that of the gimbal bar to resonate, and a protrusion signal with a strength of 1 minute is returned. The effect of making testing possible is significant.

[Brief explanation of drawings]

FIG. 1 is a perspective external view of an embodiment of a protrusion detection head assembly according to the present invention, FIG. 2(a) is a schematic diagram of a magnetic disk protrusion inspection device, and FIG. 2(b) is an external appearance of a conventional protrusion detection assembly. 2(c) is a waveform diagram of a protrusion signal, FIG. 3(a) is an external view of a protrusion detection head assembly using a ceramic core of a thin film head as a protrusion detection head, and FIG. 3(b) is a FIG. 4 is a vibration system model diagram for the protrusion detection assembly of FIG. 3(a). 1... Magnetic disk, 2... Spindle, 3.
3'... Head assembly, 3a... Metal helad core, 38'... Ceramic core, 3b, 3b'... Gimbal bar, 4... Support arm, 5... Carriage mechanism, 5a. ... Moving part, 5b... Drive motor, 5c... Threaded rod,
6.6'...Piezo element f, 6a...Connection line, 6b...
...Support rod, 7...Protrusion detection circuit.

Claims (1)

[Claims] (1) It has a small and lightweight head assembly consisting of a protrusion detection head and a gimbal bar with the protrusion detection head fixed to its tip, and the other end of the gimbal bar is attached to a carriage mechanism via a support arm, and the carriage mechanism In the magnetic disk protrusion inspection apparatus, the protrusion detection head moves and floats relative to the surface of a rotating magnetic disk, and a piezo element detects vibrations generated in the head assembly by the protrusions present on the surface. A protrusion detection head assembly characterized in that the piezo element having a natural frequency equal to the natural frequency of is elastically attached to the support arm.