JPS6120657Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present optical scheme relates to an optical positioning device for a magnetic head of a magnetic disk device.

In a magnetic disk device, information is written in a large number of concentric circles on a magnetic disk, and the written concentric recording bands or tracks are detected, a magnetic head is positioned over the tracks, and reading is performed. Conventionally, in order to perform this track detection, a special magnetic disk called a servo disk was attached separately from the information disk, the track position was magnetically recorded on this servo disk, and the track position was read from the disk. This method was commonly used. However, this method requires a separate servo disk, which increases the size and cost of the device. On the other hand, a method of optically detecting the track position has been considered.In this method, a large number of light reflective and light absorbing tracks, that is, white and black concentric tracks, are written alternately on a magnetic disk. Track position signals are obtained by optically detecting black and white tracks. Since this black and white track is written on the information recording/reproducing track, a servo disk is not required.

Note that optical readout requires a light emitting/receiving device, but since the magnetic head is extremely small and lightweight, it is not possible to incorporate a light emitting/receiving device into the magnetic head, so an optical fiber is attached to the magnetic head to transmit and receive light. Make sure to do the following. FIG. 1 shows an outline of the system, in which (a) shows a state in which optical fibers 2a, 2b are attached to a magnetic head 1, and (b) shows a procedure for detecting tracks using the fibers 2a, 2b. Fiber 2a for light emission, fiber 2b
If it is for light reception, white track 3 of disk 3
a, Fibers 2a and 2b are connected to black track 3b.
When it is in the position shown in Figure (b), the output of the light-receiving fiber 2b becomes as shown in Figure (c).
That is, since the light projected from the fiber 2a is reflected by the disk surface and received by the fiber 2b, the portions that contribute to this reflection, that is, the fibers 2a and 2b.
The brightness near the midpoint between the two determines the received light output, and if the midpoint is white, as in the position, the received light output (amplitude of the electrical signal after photoelectric conversion) is maximum,
If the area near the midpoint is black, as in the position, the received light output will be minimum, and if the area near the midpoint is black and white, as in the position, the received light output will take a medium value. By counting the number of peaks or valleys in the received light output, the number of tracks traversed by the head during reading etc. can be determined, and the counted value from a predetermined position such as the starting end indicates the desired track. Furthermore, since the magnitude of the received light output indicates the amount of positional deviation between the head and the track, the head can be accurately positioned on the track by, for example, positioning so that the received light output takes a peak value.

By the way, as an optical sensor for performing such positioning, it is preferable to embed an optical fiber in the magnetic head as schematically shown in FIG.

The optical fiber must be as thin as approximately 50 to 200 μm, depending on the width of the optical track. When embedding such a thin optical fiber in a magnetic head, it is difficult to process the fiber tip.

In addition, the tip of the fiber must be neatly polished and free of chips or scratches, but the fiber is inserted into the hole or groove provided in the magnetic head, fixed with adhesive (glass or resin), and the core and slider floated. In a structure in which the surface is polished into a flat surface and the surface of the core and slider is finished as well as the tip of the fiber, the finishing of the magnetic head and the finishing of the optical sensor are done at the same time, making it difficult to manufacture. Furthermore, if the slider comes into contact with the disk surface due to the influence of dust or the like, the fiber end surface may be chipped or damaged, resulting in poor reliability.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an optical sensor that is easy to manufacture and that does not damage the fiber end face due to contact between the magnetic head and the disk.

For this purpose, the present invention provides a magnetic disk with a large number of light-reflecting and light-absorbing centripetal tracks alternately, and optically reads out the tracks by attaching optical fibers for transmitting and receiving light to the magnetic head. , an optical positioning device for a magnetic head that performs positioning by obtaining a head position signal, characterized in that the tip of an optical fiber provided in the magnetic head is provided above the head core of the magnetic head or the air bearing surface of the slider. .

The present invention will be described in detail below with reference to the drawings. FIG. 2 is a diagram showing an embodiment of the optical sensor of the present invention, in which FIG. 2a is a side view, b is a bottom view, and c is a sectional view at A and A'.

In the figure, 1 is a head slider, 11 is a head core, 2a and 2b are optical fibers, 12
is an adhesive, and 13 is a hole.

As shown in FIG. 2, the optical sensor according to the present invention is manufactured by manufacturing a head slider 1 having a head core 11 and holes 13, 13 into which optical fibers 2a, 2b are inserted.

In this process, optical fibers 2a, 2
Since b is not attached, it can be manufactured in exactly the same way as a conventional magnetic head.

On the other hand, the tips of the optical fibers 2a and 2b are finished in advance.

Next, the optical fibers 2a and 2b are inserted into the holes 13 of the head slider 1 and then fixed with an adhesive 12.
The finished tip of b is raised above the flying surface of the head slider 1 by a distance d as shown in FIG. 2c. In other words, the distance from the disk surface (not shown) to the bottom surface (flying surface) of the head slider is
Optical fibers 2a and 2b from the disk surface
The optical fibers 2b, 2b are attached to the head slider 1 so that the distance to the tip of the optical fiber 2b is large. The distance d depends on the flying height of the head, but it may be about 110 μm.

In the optical sensor constructed in this manner, even if the magnetic head and the disk surface come into contact, the tips of the optical fibers 2a and 2b do not come into contact with the disk surface, thereby preventing damage to the optical fibers.

Further, the head slider and the optical fiber have the advantage of being easy to manufacture because they are individually finished.

As explained above, according to the present invention, an optical sensor that is easy to manufacture and can prevent damage to the optical fiber can be achieved, and is extremely effective in practice.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an optical positioning device, and FIG. 2 is a diagram showing an embodiment of the optical sensor of the present invention, in which 1 is a head slider, 11 is a head core, 2a and 2b are optical fibers, 12
is an adhesive, and 13 is a hole.

Claims (1)

[Scope of utility model registration request] A magnetic disk is provided with a large number of light-reflecting and light-absorbing concentric tracks alternately, and an optical fiber for transmitting and receiving light is inserted and fixed into a magnetic head having a head slider with a hole for inserting an optical fiber. An optical positioning device for a magnetic head that optically reads out the track and obtains a head position signal to perform positioning, the tip of an optical fiber provided in the magnetic head being connected to the head core of the magnetic head or the floating of a slider. An optical sensor in an optical positioning device for a magnetic head, characterized in that the sensor is set back from a surface.