JPS63206973A - Head positioning device - Google Patents

Abstract

PURPOSE:To eliminate an effect of the accuracy of tooth profile and to prevent the accuracy of positioning from deteriorating due to wear of teeth by making the number of teeth of a pinion more than half as many as the number of steps of a step motor and making also the pitch of teeth of a rack more than twice as much as a track pitch. CONSTITUTION:By making the number of teeth of the pinion 13 half the number of steps of the step motor 11 and also the pitch of teeth of the rack 18 double the track pitch, a contact part between the rack 18 and pinion 13 is equalized on right and left relatively to their respective teeth each other. Consequently, at the time of positioning a head to a track position, the meshing position of the rack 18 with the pinion 13 in their respective teeth profiles is in their same positional relations with regard to any tracks, so that even if the accuracy of tooth profile on the pinion 13 and rack 18 is not so good, and on the other hand even if their teeth are worn out, it is not necessary to reposition in various points in the middle of their intermesh. In this way, the accuracy of positioning the head will never deteriorate provided that the pitch is insured in accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to head positioning of a disk device, and more particularly to a head positioning device constituted by a rack and pinion.

[Prior Art] Conventionally, in a head positioning device configured with a rack and a pinion, the number of teeth of the pinion provided on the output shaft of the step motor is 2/1 or more of the number of steps of the step motor, and the pitch of the teeth of the rack is Although no example of a track pitch of 2@ or less has been found, as an example of a head positioning device using a rack and pinion,
No. 340, JP-A No. 60-136067, U.S. Patent No. 44
As described in Japanese Patent No. 28012 and shown in FIG. 5, a positioning device for a head 4 in a disk device using a step motor 1, a rack 2, and a pinion 3 was known.

FIG. 5 is a perspective view of a conventional head positioning device,
FIG. 6 is a detailed view of the rack and pinion of a conventional head positioning device.

[Problems to be Solved by the Invention] However, in conventional head positioning devices, the pitch of the concentric recording portions (hereinafter referred to as tracks) is as small as several hundreds of micrometers or less. A hybrid step motor 1 with 100 divisions or more in one rotation is used, and the teeth 1 of the rack 2 and pinion 3 are
The number of pinion teeth is less than one-fifth of the number of steps of the step motor, and the pitch of the rack teeth is more than five times the track pitch. ), and the factors that determine the positioning accuracy of the head 4 are the division accuracy of the step motor 1, the tooth profile accuracy of the rack 2, and the tooth profile precision of the pinion 3, and high precision is required for each.

Furthermore, due to the repeated movement of the head 4 by the rack 3 and pinion 2, the tooth profiles of the rack 3 and pinion 2 are worn away at the shaded portions of the tooth profiles in FIG.
The reason for this is that even if the tooth profile is an involute tooth profile, slipping occurs at the contact area between the teeth of the rack 3 and the pinion 2 in the meshing area other than the pitch circle 5, which cannot be avoided.

With such worn teeth, in a head positioning device that positions the head on five or more tracks while one tooth is meshing, the rack or pinion teeth will continue to wear with respect to the initial positioning position. As time goes on,
There is also a problem that the positioning position changes.

The present invention is intended to solve these conventional problems, and its purpose is to eliminate the influence of the tooth profile accuracy of the rack and pinion, and to prevent the head positioning accuracy from deteriorating due to wear of each tooth. The present invention provides a head positioning device using a rack and pinion.

[Means for Solving the Problems] In order to solve the above problems, a head positioning device for a disk drive according to the present invention includes a head for performing concentric recording or reproduction on a disc-shaped recording medium; a step motor for moving and positioning the head in the radial direction of the recording medium every step or every plural steps;
a pinion provided on the output shaft of the step motor and configured with teeth having a number of steps equal to or more than half the number of steps of the step motor; a carriage on which the head is mounted; It is characterized by comprising a rack having a pitch less than twice the pitch of concentric recording and meshing with the pinion.

[Function] According to the above structure of the present invention, when the head is positioned at a track position, the meshing positions of the tooth profile of the rack and the tooth profile of the pinion are in the same positional relationship on every track (for example, one track is When the step motor moves with one step and the number of #B of the pinion is half the number of steps of the step motor, it moves every other rack.) Even if the tooth profile accuracy of the pinion and rack is poor,
Even if the teeth wear out, there is no need to position the head at multiple locations in the middle of tooth meshing, so as long as the pitch accuracy is maintained, there is no deterioration in the head positioning accuracy.

[Embodiment] FIG. 1 is a perspective view of a head positioning device for a disk device in an embodiment of the present invention, and FIG.

FIG. 3 is a detailed diagram illustrating the engagement of the rack and pinion in FIG. 1.

In this embodiment, the outer diameter of the flexible disk, which is generally called a 3.5-inch flexible disk, is 3.5 inches.
This will be explained by referring to devices around the inch.

In FIG. 1, a pinion 13 is integrated with an output shaft 12 of a step motor 11. As shown in FIG.

A lower head 16 and an upper carriage 17 are mounted on a carriage 15 which is configured to be movable in the axial direction with respect to the guide shaft 14 . In FIG. 1, the upper carriage 17 is partially omitted to make the figure easier to understand.

The carriage 15 is configured to be rotatable around the guide shaft 14, and has a rack plate 19 provided with a rack 18.
is fixed to the carriage 15, and the rack 18 and pinion 13 are fixed to the carriage 15.
is engaged with the stopper in the direction of rotation of the carriage 15.

Further, the lower part of the rack plate 19 is bent into an L-shape, and the rack plate 19 is absorbed by an adsorption magnet 21 provided on the frame 20, thereby applying appropriate pressurization to the rack 18 and pinion 13. In this embodiment, since the rack plate 19 was made of a magnetic material, the above structure was possible. However, if the rack plate 19 is made of a non-magnetic material, another magnetic material may be attached to the carriage 15. Alternatively, it is also possible to attach the attraction magnet 21 to the carriage 15 and fix the magnetic material to the frame 20.

In this example, the pitch between tracks is 187.5μ.
m, and the pitch of the teeth of the rack 18 is 2 of the track pitch.
The diameter of the output shaft 12 is 1.5 mm, and the number of teeth of the pinion 13 is 10 (module 0.11).
9) It is (2 of the number of steps of the step motor)
(1/1) When configured as above, rack 18 and pinion 13
The engagement is as shown in Figures 2 and 3.

In Fig. 2, when the pinion 13 and the rack 18 are engaged as shown in the figure, when the step motor 11 is rotated for one step (because a four-phase permanent step motor is used in this embodiment), , when only one phase is switched from a state where two phases are energized to the next excitation phase, the step motor rotates one step 18 @.)
Pinion 13 also rotates 18 degrees, and pinion 13 and rack 1
The engagement of No. 8 is as shown in Figure 3. FIG. 3 is a diagram in which the rack 18 has been moved by 1/2 pitch with respect to the center of rotation of the pinion 13 in FIG. 2. As can be seen from these figures, by setting the number of teeth on the pinion 13 to half the number of steps on the step motor 11 and making the pitch of the teeth on the rack 18 twice the track pitch, the rack 18 and The contact portions of the pinion 13 are made even on the left and right sides of each tooth, and even if the teeth of the rack 18 or pinion 13 wear out as shown in FIG. 6, the deterioration in positioning accuracy can be minimized. .

Note that although Figures 2 and 3 show the case where the meshing of the teeth of the rack 18 and pinion 13 is ideally adjusted so that it is even on the left and right sides, it is possible that the meshing of these teeth is not completely equal on the left and right sides. However, the above-mentioned effects can be obtained.

Furthermore, a small gear with a module of 0.119,
By combining a step motor with a small number of steps (20 steps), the outer surface diameter of the pinion can be reduced to 1.5 mm, and the pinion can be configured directly on the shaft of the step motor, improving the accuracy of the pinion and reducing the motor shaft diameter. Because it is thin, friction loss on the motor shaft can be reduced, and the motor bearing can be replaced with an inexpensive metal bearing instead of an expensive ball bearing.

FIG. 4 is a diagram illustrating the engagement of the rack and pinion of the head positioning device of the flexible disk drive device in another embodiment of the present invention.

In this embodiment as well, the head positioning device has the same structure as that shown in FIG.

In FIG. 4, the rank 18 and pinion 13 are meshed, and the contact points are three points A, B, and C.

The number of teeth of the pinion 13 is the same as the number of steps of the step motor 11, and the pitch P1 of the teeth of the rack 18 is the same as the track pitch.

In such a configuration, when the step motor 11 rotates one step, the teeth of the pinion 13 and the teeth of the rack 18 also move by one tooth, so the contact area between the rack 18 and the pinion 13 is almost the same as before the movement A, If there are three points B and C and the rack 18 is to be positioned on each track, the points A and B are
, as long as the pitch accuracy at point C is sufficient, the accuracy of the intermediate tooth profile does not affect the positioning accuracy at all.

Similarly, the number of teeth of the pinion 13 in FIG. 4 is set to three times the number of steps of the step motor 11, and the pitch P1 of the teeth of the rack 18 is set to 1/n of the track pitch 8 (n is an integer). , the pinion 13 has a rack 1 every n teeth.
Since positioning is performed by meshing with the teeth of the rack 18, the contact between the teeth of the toothed pinion 13 of the rack 18 is the same as that of this embodiment, and the same effect can be obtained.

Although the flexible disk drive device has been described above based on a specific embodiment, the present invention can be similarly implemented in hard magnetic disk devices, optical disk devices, etc., and has a wide range of applications.

[Effects of the Invention] As explained above, the present invention is characterized by making the number of teeth of the pinion more than half the number of steps of the step motor and making the pitch of the teeth of the rack less than twice the track pitch. This eliminates the need to position the head at several locations in the middle of one tooth of the pinion and rack, and as long as the pitch g of the rack and pinion teeth is sufficient, the influence of the It degree of the tooth profile is eliminated, and the tooth This has the effect of providing a head positioning device that can prevent deterioration of positioning accuracy due to wear.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a head positioning device of a flexible disk drive device according to the present invention. FIGS. 2, 3, and 4 are detailed views illustrating the engagement of the rack and pinion of the head positioning device of the present invention. FIG. 5 is a perspective view of a conventional head positioning device. FIG. 6 is a detailed view of the rack and pinion of a conventional head positioning device. 11・・・・・・・・・・・・・・・Step motor 13・・・・・・・・・・・・Pinion 15
・・・・・・・・・・・・・・・ Carriage 16...
・・・・・・・・・・・・Lower head 18・・・・・・
・・・・・・・・・Rack Figure 1 10 R Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1) A head for performing concentric recording or reproduction on a disk-shaped recording medium, and a step motor for moving and positioning the head in the radial direction of the recording medium at each step or every plural steps; 1/2 of the number of step motor steps provided on the output shaft of the step motor
Consisting of a pinion made up of the above-mentioned teeth, a carriage on which the head is mounted, and a rack provided on the carriage and having a pitch of teeth that is less than twice the pitch of concentric recording of the recording medium and meshing with the pinion. head positioning device.