JPS6233372A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve a memory capacity by constituting a mechanism for operating a magnetic head having larger track pictures as directing toward an outer periphery with respect to a magnetic recording medium. CONSTITUTION:In order to read no track information adjacent to a magnetic head, a width of the track A has to establish the relation indicated by the inequality (1) between a track pitch P and the quantity of an off-track T. The quantity of the off-track is proportional to a fixed quantity T0 or to a radius R of the track. The quantity of the off-track T is represented by the equation of (2). In order to increase a memory capacity, the width of the track A has to be made narrow, however, when the track width A is made narrow, S/N during the off-track becomes small. Then, when a cam 10 is disposed and rotated, a protrusion 11a engaging with a guide groove 10a slides with respect to a guide groove 10a to move heads 5, 5' radially of a magnetic recording medium 1 so as to have more extent of movement toward an outer periphery part. Thereby, a reliability of the device is not deteriorated and the memory capacity can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a magnetic recording/reproducing device, and more particularly to a device that increases recording capacity while preventing deterioration in reliability of the device due to off-track.

<Prior Art> Floppy disk drives (EDDs), which utilize disk-shaped magnetic recording media called floppy disks, have shown rapid growth as microcomputers and various office automation equipment (particularly word processors) have developed. There is. However, as the use of the device increases, not only the advantages of the device but also its problems are beginning to be pointed out.

3 and 4 show the conventional structure of a magnetic recording/reproducing device. In the figure, reference numeral 1 denotes a disk-shaped magnetic recording medium, which is held between a spindle 2 and a collet 3 and rotated by a spindle motor 4. As shown in FIG. 5 and 5'
is a magnetic head, 6 is a stepping motor, 7 is a pulley,
8 is a belt, and 9 is a head carriage. Due to the rotation of the stepping motor 6, this rotational force is generated by Boo IJ 7,
The signal is transmitted to the head carriage 9 via the belt 8 and moves the magnetic head 5.5' in the radial direction of the magnetic recording medium 1. In this case, the amount of movement of the magnetic head 5.5' is determined quantitatively by the stepping angle of the stepping motor 6 and the radius of the pulley 7.

In the device configured as described above, each trunk In between, there is a part that does not input or output data. Here, the occurrence of off-trunk is caused not only by the dimensional accuracy of each component and the chucking error when installing the magnetic recording medium 1, but also by
This may be due to differences in expansion of the magnetic recording medium 1 due to temperature or humidity. Of these, in the former case, the amount of off-track is constant regardless of the track radius, but in the latter case, it depends on the track radius, and since the magnetic recording medium 1 is circular, the amount of elongation is greater at the outer periphery, so the amount of off-track is constant regardless of the track radius. The amount of tracks increases at the outer periphery. For this reason, conventionally, track pinch (the distance between the centers of two adjacent tracks, including the blank space where data is not input/output) is limited to the amount of off-trunk at the outermost periphery, and this track pinch made up the trunk. For this reason, it is difficult to increase the storage capacity of the entire magnetic recording medium, and if the recording density is set high, the track width must be narrowed, which impairs reliability.

<Problems to be Solved by the Invention> As described above, the present invention provides that if the trunk pinch of a magnetic recording medium is made constant based on the track pitch at the outermost circumference, an unnecessarily large trunk pitch at the inner circumference may occur. To provide a magnetic recording and reproducing device which is constructed in view of the problem that the storage capacity of the entire recording medium is reduced, and which can improve the storage capacity without reducing the reliability of the device. With the goal.

<Means for Solving the Problems> In order to achieve this object, the present invention configures a mechanism for operating a magnetic head so that the track pitch becomes larger on the outer periphery of a magnetic recording medium, and The structure accommodates the expansion and contraction of the magnetic recording medium and improves the storage capacity without reducing the reliability of the device.

<Example> First, prior to a detailed explanation of the present invention, a track pitch determination method in the prior art will be specifically explained.

In order to prevent the magnetic head from reading information on adjacent tracks, the following relationship between the track width A, the track pitch P, and the off-track fiT must be established.

P≧A+T... (1) However, as described above, the off-track amount T includes a constant amount T0 that does not depend on the track radius, and a constant amount T0 that is proportional to the trunk radius R. Therefore, it is necessary to determine the off-track amount T by considering both of these factors, and its setting is based on the following equation.

T-TO+C-R... (2) (C is a proportionality constant) As is clear from this equation, off-track tT is maximum at the outermost trunk, and becomes smaller at the inner trunk. Therefore, if the track pitch P is kept constant, the track width A is regulated by the maximum off-track i1T on the outermost track, and the only way to increase the storage capacity is to narrow this track width A. . Decreasing the trunk width A means that the S/N ratio (signal-to-noise ratio) during off-track becomes smaller, which lowers the reliability of the device.

The present invention has been constructed in consideration of the above points, and its basic feature is to change the track pitch in accordance with the radius of the magnetic recording medium.

In this case, the trunk pitch P can be expressed by the following equation.

P=Po+ -R... (3) (p is a constant value, K is a constant) In Figs. is a spiral guide groove 1
0a is formed. A stepping motor 6 is a driving device for rotating the cam, and the cam 10 and the cam driving device 6 constitute a head moving device. On the other hand, a guide member 11 having a protrusion 11a formed at the lower end is attached to the base (left side in the figure) of the head carriage 9 having the magnetic head 5.5' at the tip. is engaged with.

Next, the shape of the guide groove 10a is specifically determined as follows.

That is, if the radius of the nth track 12 from the innermost track is Rn, the radius of the n+1st track 12 is Rfi+
1 becomes as follows from (3) above.

R, +, -Rn+P = Rn+P, +CRn = Pa + (HC)Rn From the above equation, the nth track radius Rn can be expressed by the following equation.

R=1 (R11 is the radius of the innermost track, n≧1) Therefore, if the point on the curve to be sought is expressed in polar coordinates and expressed as (γ, θ),
According to Figure 2, using equation (4) above, (r, θ) = (L+ Lz Rfi, nψ) (ψ
is the step angle of the stepping motor).

With the above configuration, by rotating the cam 10 by a predetermined angle, the protrusion 11a engaged with the guide groove 10a slides with respect to the guide groove 10a as the cam 10 rotates, and the head 5 is moved through the head carriage 9. .5' is moved in the radial direction of the magnetic recording medium 1 so that the amount of movement of the outer peripheral portion is increased.

This point will be further explained using specific numerical values.

The track radius of the outermost track is 57 fl, the track radius of the innermost trunk is 37 fl, and the number of tracks is 101.
If it were a book, the track pinch would be 20OA1111. The off-track amount is 82μ on the outermost circumference and 7 on the innermost circumference.
Since it is 0 μm, in the conventional device, the trunk width is 118 μl due to the above-mentioned second (1), and the S/N ratio decreases by 7.8 db in the innermost track due to the off-trunk.

On the other hand, in this embodiment, if the number of trunks is the same as in the conventional device, the n-th track radius R7 will be as shown in the following equation.

becomes. At the outermost circumference, the track pitch is 0.2061mm
Therefore, the trunk width is 124.1 μm.

On the innermost track, the S/N ratio decreases by 4.4 db when off-track, which is 3.4 db compared to the prior art described above.
It was confirmed that the S/N ratio could be increased by 4 db and the reliability was improved.

Furthermore, if the amount of decrease in the S/N ratio at the innermost track is set to be the same as in the conventional device, the number of tracks can be set to 104, and the storage capacity can be increased by about 3%.

Note that the structure for moving the head is not limited to that shown in FIGS. 1 and 2, and may be the following structure. That is, instead of the cam 10 having the guide groove formed therein, the hand 5 is used.
．． 5' is basically moved by a pulley and belt as shown in Figures 3 and 4, and by eccentrically positioning the rotation axis of this pulley, the rotation angle of the pulley (the rotation angle is constant by the stepping motor) The amount of movement of the belt may be made different depending on the amount of movement of the belt. With this configuration, it is possible to implement the conventional device without much modification.

In addition, in the illustrated device, the moving locus of the belt carriage 9 is a straight line and coincides with the radius of the magnetic recording medium 1, but in addition to this configuration, for example, a fulcrum may be formed at a predetermined position of the belt carriage 9. However, the head 5, 5' is configured to rotate around this fulcrum, that is, the movement locus of the heads 5, 5' is strictly speaking the distance from the fulcrum to the head 5, 5' as a radius. It is also possible to apply this method to a circular arc. Therefore, "the movement of the magnetic recording medium in the radial direction" includes not only movement along the radius in a strict sense, but also movement in which the movement locus is an arc.

Effects> As described above, the present invention allows the magnetic head to be moved so that the pitch of the tracks formed on the magnetic recording medium increases from the outer periphery, so the recording capacity can be increased without reducing the reliability of the device. can be done.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a head moving device showing an embodiment of the present invention, FIG. 2 is a plan view of FIG. 1, FIG. 3 is an exploded perspective view showing the structure of a conventional device, and FIG. 1 is a side view of the device shown in the figure; FIG. 1...Magnetic recording medium 5.5'...Magnetic head
6...Stemping motor 7...Pulley
8...Belt 9...Belt carriage 10...Cam 10a...Guide groove 11...Guiding member Fig. 1 5 Magnetic cable 8F 5' Ciro Stepping [-ta IO for guiding cam 11a protrusion

Claims (4)

[Claims] (1) A disc-shaped magnetic recording medium is rotatably held by a rotation mechanism, and a magnetic head is arranged that is movable in the radial direction with respect to the magnetic recording medium,
1. A magnetic recording/reproducing device comprising a head moving device having a mechanism for controlling the movement of a magnetic head so that the track pitch becomes larger toward the outer circumferential side of a magnetic recording medium. (2) The head moving device is composed of a cam with a spiral guide groove formed therein and a cam drive device that rotates the cam, and the head carriage supporting the magnetic head is directly or indirectly connected to the guide groove. A magnetic recording/reproducing device according to claim (1), characterized in that the magnetic recording/reproducing device is engaged with the magnetic recording/reproducing device. (3) Attach a guide member to the base of the head carriage,
The magnetic recording/reproducing device according to claim 2, wherein the protrusion of the guide member is configured to engage with the guide groove. (4) The head moving device is composed of a pulley rotated by a stepping motor and a belt moved by the pulley, and the rotation axis of the pulley is positioned eccentrically from the center of the pulley. Range No. 1
) The magnetic recording and reproducing device described in item 2.