JP2680995B2 - Signal transmission cable for magnetic disk unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal transmission cable for transmitting a signal read by a magnetic head to an amplification recognition circuit in a magnetic disk device.

[0002]

2. Description of the Related Art In a magnetic disk device, a conventional signal transmission cable for transmitting a signal read by a magnetic head to an amplification recognition circuit mainly uses a single-layer flexible wiring board (FPC), which is very small. In rare cases, a two-layer flexible wiring board (FPC) may be used. In such a case as well, a signal (reproduction signal) read by one magnetic head is transmitted to an amplification recognition circuit to form a closed circuit. The two signal lines are provided in one layer.

FIG. 4 is a block diagram showing an example of a signal transmission cable of such a conventional magnetic disk device, and FIG.
Is a diagram showing a configuration in the vicinity of the VCM coil of the example of FIG.
(A) is a top view, (b) is an expanded sectional view of B part.

As shown in FIG. 4, a read / write integrated circuit (R / WI) having a magnetic head 15 and an amplification recognition circuit is provided.
C) 18 is connected to a flexible wiring board (FPC) 20 by a first pattern 20a and a second pattern 20b provided at a predetermined interval, and these form a closed loop.

Therefore, when a magnetic field or an electric field is applied from the outside, noises of different magnitudes are generated in the first pattern 20a and the second pattern 20b due to a slight difference in their arrangement positions. The difference between the noises generated in the first pattern 20a and the second pattern 20b is superimposed on the signal from the magnetic head 15 and amplified in the R / WIC 18, so that the signal output from the R / WIC 18 includes a reproduction signal. Is superimposed with a large value of noise and output.

For example, in FIG. 5, a positioner 14 for moving the magnetic head 15 to a designated position on a magnetic disk (magnetic recording medium) is a voice coil motor coil (VCM coil) coupled to the end portion. The VCM coil 16 is driven by energizing the VCM coil 16, but the energization of the VCM coil 16 generates a fluctuating magnetic field (magnetic field) 20 c around the VCM coil 16. Since the strength of the magnetic field 20c is inversely proportional to the square of the distance from the VCM coil 16, the first pattern 2 provided on the FPC 20 is used.
0a and the noise generated in the second pattern 20b are V
The noise of the first pattern 20a close to the CM coil 16
The noise is larger than the noise of the second pattern 20b far from the VCM coil 16. The difference in noise between the first pattern 20a and the second pattern 20b is amplified in the R / WIC 18, is superimposed on the reproduced signal, and is output.

It is difficult to eliminate noise from the signal output from the R / WIC 18, and particularly in a high-performance magnetic disk device which performs high-density recording, the ratio of the reproduced signal to the noise is S. This is especially difficult because the / N ratio increases.

[0008]

As described above, in the signal transmission cable of the conventional magnetic disk device, the two signal lines connecting one magnetic head and the R / WIC having the amplification recognition circuit are Since they are arranged side by side at a predetermined interval on one layer of the FPC, noise of different magnitude is generated in the two signal lines when an external magnetic field or electric field is applied. Since the difference between R and WIC is amplified in the R / WIC, it has a drawback that a large value of noise is superimposed and output to the signal output from the R / WIC.

[0009]

A signal transmission cable of a magnetic disk device according to the present invention has a two-layer structure in which layers are stacked one above the other, and for each magnetic head of one or more magnetic heads of the magnetic disk device, One signal line of the two signal lines forming a closed pattern by connecting the corresponding magnetic head and the amplification recognition circuit is provided in one layer of the two-layer structure, and the other signal line is formed. Line the other one of the two-layer structure
The flexible wiring board is provided at a position overlapping the one signal line of the layer.

[0010]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a structure in the vicinity of the VCM coil of the embodiment of FIG. 1, (a) is a plan view, and (b) is an A part. FIG. 3 is an enlarged sectional view of FIG. 3, and FIG. 3 is a plan view showing an example of a magnetic disk device adopting the embodiment of FIG.

In FIG. 3, a magnetic disk device 1 includes a spindle motor (SPM) 3 for rotating a magnetic disk (magnetic recording medium) 2 and a magnetic head 5 for recording / reproducing information on / from the magnetic recording medium 2. And a voice coil motor attached to the other end of the positioner 4 and supplied with an electric current to move the magnetic head 5 to a specified position on the magnetic recording medium 2. The coil (VCM coil) 6, the voice coil motor (VCM) 7 that cooperates with the VCM coil 6 to drive the positioning operation of the positioner 4, and the amplification recognition circuit that recognizes and amplifies the reproduction signal of the magnetic head 5 are included. A read / write integrated circuit (R / WIC) 8 is provided, and the magnetic head 5 and the R / WIC 8 are connected to a flexible wiring board (FPC).
It is connected at 10.

The FPC 10 has a two-layer structure in which the FPC 10 is vertically laminated. As shown in FIG. 1, the FPC 10 has a magnetic head 5 and an R / W.
In order to connect with IC8, it has two signal lines, the 1st pattern 10a and the 2nd pattern 10b, and these have formed the closed loop. The first pattern 10a and the second pattern 10b are used when the positioner 4 carries a plurality of magnetic heads 5 (the magnetic recording medium 2 has a plurality of recording surfaces, one for each recording surface). (When one or a plurality of magnetic heads 5 are provided) are provided for each of the magnetic heads 5.

First pattern 10a and second pattern 1
One of 0b is one of the two-layer structure of the FPC 10.
The other signal line provided in the layer is the FPC10.
It is provided in another one layer of the two-layer structure. Moreover, these two signal lines are provided at positions where they overlap each other and are very close to each other.

By configuring the FPC 10 in this way, the magnitudes of noises generated in the two signal line first patterns 10a and the second patterns 10b are almost the same when an external magnetic field or electric field is applied to the FPC 10. Therefore, the noises generated in the first pattern 10a and the second pattern 10b cancel each other out, and the noise output is almost not superimposed on the signal output from the R / WIC 8.

For example, referring to FIG. 2, a positioner 4 for moving the magnetic head 5 to a designated position on the magnetic recording medium 2 has a VCM coil 6 coupled to its end.
It is driven by energizing. By energizing the VCM coil 6, a fluctuating magnetic field (magnetic field) 10c is generated around the VCM coil 6. The strength of the magnetic field 10c is inversely proportional to the square of the distance from the VCM coil 6,
Since the first pattern 10a and the second pattern 10b provided on the FPC 10 are almost equidistant from the VCM coil 6, the first pattern 10a and the second pattern 1 are provided.
The magnitude of the noise generated in 0b is almost the same. Therefore, the noise that is superimposed on the reproduced signal amplified by the R / WIC 18 and output is minimal.

[0017]

As described above, the signal transmission cable of the magnetic disk device of the present invention uses a flexible wiring board having a two-layer structure laminated vertically, and uses one magnetic head of the magnetic disk device. One signal line of the two signal lines that form a closed pattern by connecting to the amplification recognition circuit is provided in one layer of the two-layer structure of the flexible wiring board, and the other signal line is connected. By providing the other signal layer of the two-layer structure and arranging the two signal lines thereof so as to overlap with each other, one magnetic field is applied when a magnetic field or an electric field is applied to the flexible wiring board from the outside. Corresponding to the head, the noises generated in the two signal lines can be made to have almost the same magnitude, and the noises generated in the two signal lines cancel each other out, so that they are output from the R / WIC. Noise on the signal There is an effect that it is possible to not be superimposed almost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

2A and 2B are diagrams showing a configuration in the vicinity of the VCM coil of the embodiment of FIG. 1, in which FIG. 2A is a plan view and FIG. 2B is an enlarged cross-sectional view of an A portion.

FIG. 3 is a plan view showing an example of a magnetic disk device adopting the embodiment of FIG.

FIG. 4 is a block diagram showing an example of a signal transmission cable of a conventional magnetic disk device.

5A and 5B are diagrams showing a configuration in the vicinity of the VCM coil of the example of FIG. 4, in which FIG. 5A is a plan view and FIG. 5B is an enlarged sectional view of a B part.

[Explanation of symbols]

1 magnetic disk device 2 magnetic disk (magnetic recording medium) 3 spindle motor (SPM) 4.14 positioner 5.15 magnetic head 6.16 voice coil motor coil (VCM coil) 7 voice coil motor (VCM) 8.18 write / read Integrated circuit (R / WIC) 10 ・ 20 Flexible wiring board (FPC) 10a ・ 20a First pattern 10b ・ 20b Second pattern 10c ・ 20c Magnetic field

Claims (2)

(57) [Claims] 1. A signal line having a two-layer structure of vertically stacked layers, and for one or more magnetic heads of a magnetic disk device, each signal line is connected to an amplification recognition circuit to form a closed pattern. One of the signal lines is provided in one layer of the two-layer structure, and the other signal line is overlapped with the one signal line of the other one layer of the two-layer structure. A signal transmission cable for a magnetic disk device, comprising a flexible wiring board provided at a position. 2. A closed pattern is formed by connecting a corresponding magnetic head and an amplification recognition circuit for each magnetic head of a plurality of magnetic heads of a magnetic disk device, which has a two-layer structure of vertically stacked layers. One signal line of the two signal lines is provided in one layer of the two-layer structure, and another signal line is provided of the one signal of another one layer of the two-layer structure. A signal transmission cable for a magnetic disk device, comprising a flexible wiring board provided at a position overlapping the line.