JPH0684564U - Head carriage drive mechanism - Google Patents

Abstract

(57) [Summary] [Object] An object of the present invention is to provide a head carriage drive mechanism configured to transmit rotation of an output shaft of a head carriage drive motor to a lead screw through a plurality of gears. A head carriage drive mechanism 11 includes a head carriage 3, a lead screw 12 screwed to the head carriage 3, and a head carriage drive motor 8 that rotationally drives the lead screw 12 via gears 13 and 14. . The screw pitch P of the lead screw 12 is set to 1 / n of the conventional screw pitch p, and the rotation of the gear 13 axially attached to the lead screw 12 and the gear 14 axially attached to the output shaft 8a of the motor 8 for driving the head carriage. The ratio is 1: n.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a head carriage driving mechanism, and more particularly to a head carriage driving mechanism configured to transmit rotation of an output shaft of a head carriage driving motor to a lead screw via a plurality of gears.

[0002]

[Prior art]

 For example, in a magnetic disk device that performs magnetic recording / reproduction when a flexible magnetic disk housed in a cartridge is mounted, a lead screw is screwed into a head carriage that supports the magnetic head, and a head carriage drive motor is installed. Thus, the lead screw is rotationally driven to move the head carriage in the disk radial direction.

However, in the above magnetic disk device, since the output shaft of the head carriage driving motor and the lead screw are integrated, the head carriage driving motor is arranged so as to project to the rear of the lead screw. It was set up. Therefore, the position of the head carriage driving motor has been an obstacle to downsizing of the apparatus. For this reason, a head carriage drive motor is provided on the side of the lead screw to reduce the space behind the device and reduce size, and a gear is attached to the output shaft of the lead screw and head carriage drive motor. A head carriage drive mechanism has been developed that is configured to transmit the rotation of the motor to the lead screw.

As a flexible magnetic disk device that employs this type of head carriage drive mechanism, there is one shown in FIG.

In the figure, reference numeral 1 denotes a magnetic head, which is driven in the radial direction (X direction) of the flexible magnetic disk 2 to perform magnetic recording / reproduction on the flexible magnetic disk 2. The magnetic head 1 is supported by the head arm tip of the head carriage 3 and moves together with the head carriage 3.

The right side of the head carriage 3 is slidably guided by engaging with the guide shaft 4 in FIG. 1, and an engaging portion 6 having a pin for engaging the lead screw 5 is projected on the left side thereof. There is. Therefore, the lead screw 5 is driven to rotate and the head carriage 3 is slidably guided.

A gear 7 is axially attached to the end of the lead screw 5, and a gear 9 axially attached to an output shaft 8a of a head carriage driving motor 8 composed of a stepping motor meshes with the gear 7. ing. Therefore, the rotational driving force of the head carriage driving motor 8 is transmitted to the lead screw 5 via the gears 9 and 7. The magnetic head 1 moves together with the head carriage 3 by a distance according to the rotation angle of the lead screw 5.

Here, the operation of the head carriage drive mechanism having the above configuration will be described in detail.

For example, in the case of a 3.5-inch magnetic disk, the track density for magnetic recording is set to 135 TPI (Track Per Inch), and the track pitch (distance between tracks) is approximately 0.1875 mm. Therefore, the pitch of the lead screw 5 is set to 1.875 mm so that the magnetic head 1 moves a distance of 10 tracks while the lead screw 5 makes one rotation.

In the case of the configuration shown in FIG. 5, the rotation ratio of the gear 7 and the gear 9 is set to 1: 1 in order to facilitate the rotation control of the head carriage driving motor 8.

[0011]

[Problems to be solved by the device]

 When the gear is used as the transmission mechanism as described above, the standard of the tolerance as the cumulative pitch error is determined by "JIS B1702 (accuracy of spur gear and helical gear)", and it is manufactured based on this standard. It For example, when the pitch circle diameter of the gears 7 and 9 is φ10 mm, the pitch circumference of the gears 7 and 9 is 31.4 mm, but in the JIS standard level 5, the gears 7 and 9 are 31 It is recognized that the error in the circumferential direction up to 57 μm during a rotation of 4 mm (one rotation) is within the allowable range of the accumulated pitch error.

The pitch circle error is caused by, for example, a molding error when molding the gears 7, 9 or a center deviation of the shafts of the gears 7, 9 and the center of the pitch circles of the gears 7, 9 (rotation center). It is conceivable that this may occur due to the deviation and eccentricity. FIG. 6 is a diagram showing a change in pitch circle error when the gears 7 and 9 are rotated in the head carriage drive mechanism having the above-mentioned configuration. In the figure, the vertical axis shows the pitch circle error, and the horizontal axis shows the rotation speed of the gear.

When the axes of the gears 7 and 9 coincide with the point P ₁ which is the center of the pitch circle, the error due to the eccentricity during rotation becomes 0, and the change in the pitch circle error does not appear. However, in FIG. 6, if the axis of the gear 7 and 9 is deviated to the point P _2, since the gear 7, 9 and against the point P ₁ is the center of the pitch circle rotates eccentrically, the point P ₂ The radius up to the tooth tip of the gears 7 and 9 centering around will vary with rotation. As a result, the amount of displacement in the circumferential direction with respect to the rotation angle increases or decreases depending on the rotational position of the gears 7 and 9, and over-feeding and under-feeding occur alternately while the gears 7 and 9 make one revolution. Repeated.

Such a gear feed error affects the feed accuracy of the lead screw 5 that moves the head carriage 3. As described above, since one pitch of the lead screw 5 is 1.875 mm (distance for 10 tracks), the rotational angle accuracy error ratio of the gears 7 and 9 influences while moving this length, A feed error of 0.057 / 31.4 (rolling angle accuracy) x 1.875 = 0.0034 mm will occur.

FIG. 7 is a waveform diagram showing changes in the feed error of the head carriage 3. In the figure, the vertical axis represents the feed error, and the horizontal axis represents the rotation speed of the lead screw 5.

From the figure, it can be seen that the rotation speed changes in one cycle (10 tracks) corresponding to the change in the gear error. The + error here indicates excessive feed, and the − error indicates excessive feed.

Further, since the movement of the head carriage 3 is performed via the two gears 7 and 9, a combined wave in which the waveforms of the two gears are combined, that is, 0.0034 × 2 = 0.00 at the peak time. A feed error of 68 mm will occur.

Further, the feed error of the head carriage 3 due to the influence of the pitch circle error has a waveform diagram as shown in FIG. This figure is a composite wave of the rotation amount fluctuations of the gears 7 and 9, and shows a broken line when the head carriage 3 moves from the inside to the outside and a solid line when the head carriage 3 moves from the outside to the inside. In this way, when the pitch circle error of the gears 7 and 9 and the feed error of the head carriage 3 are combined, the fluctuation largely changes within a range of about ± 10 μm, and the accuracy of the seek operation of the head carriage 3 is increased. However, there is a problem that it becomes impossible to support high density recording.

Therefore, an object of the present invention is to provide a head carriage drive mechanism that solves the above problems.

[0020]

[Means for Solving the Problems]

 According to the first aspect of the present invention, there is provided a head carriage which supports a magnetic head and is slidable in a radial direction of a magnetic disk, a lead screw screwed to the head carriage and having a screw pitch p, and a head carriage driving device. A head carriage drive mechanism having a plurality of gears that mesh to transmit rotation of an output shaft of a motor to the lead screw, wherein a screw pitch of the lead screw is p / n, and the head screw is attached to the lead screw. The rotation ratio between the first gear and the second gear mounted on the output shaft of the head carriage driving motor is 1: n.

According to a second aspect of the invention, a magnetic head is slidably provided in a radial direction of the magnetic disk so as to form a plurality of tracks concentrically on the magnetic disk, and a head carriage is provided slidably. A head carriage drive mechanism having a lead screw screwed into the head carriage and having a screw pitch p, and a plurality of gears meshing with each other to transmit rotation of an output shaft of a head carriage driving motor to the lead screw. The screw pitch p of the lead screw is set so that the magnetic head of the head carriage moves within a range of 1 to 5 tracks magnetically recorded on the magnetic disk while the lead screw makes one revolution.

[0022]

[Action]

 According to claim 1, the feed error of the magnetic head can be reduced by setting the screw pitch of the lead screw to p / n, and the rotation of the gear on the lead screw side and the gear on the head carriage drive motor side can be reduced. By setting the ratio to 1: n, the lead screw with the screw pitch p / n is driven at the n-fold speed without changing the rotation speed of the head carriage drive motor at the speed for driving the lead screw with the screw pitch p. By doing so, the influence of the cumulative pitch error of the gear can be reduced.

According to the second aspect, the screw pitch p of the lead screw is set so that the magnetic head moves within a range of 1 to 5 tracks magnetically recorded on the magnetic disk while the lead screw makes one rotation. Thus, it is possible to reduce the feed error of the magnetic head.

[0024]

【Example】

 1 and 2 show an embodiment of a head carriage drive mechanism according to the present invention. The same components as those in FIG. 5 described above are designated by the same reference numerals and the description thereof is omitted.

In both figures, in the head carriage drive mechanism 11 of the flexible magnetic disk device, the screw pitch P of the lead screw 12 is set to 1 / n (n> 1) of the conventional screw pitch p (P = p / N). That is, the head feed error per one rotation of the lead screw 12 is generated by “the angular error ratio of the cumulative pitch error of one rotation of the gear × the screw pitch P”. It can be seen from this equation that if the screw pitch P of the lead screw 12 is reduced, the head feed error is reduced.

In this embodiment, let us consider a case where the screw pitch P of the lead screw 12 is set to 1/2 of the conventional screw pitch p. Thus, when the screw pitch P is 1/2 of the conventional screw pitch p, 1 pitch of the lead screw 12 is 1/2 of the conventional 1 pitch = 1.875 mm, and P = 0.93775 mm. .

Therefore, the magnetic head 1 moves a distance of 5 tracks during one rotation of the lead screw 12, and the moving distance of the magnetic head 1 per one rotation of the lead screw 12 is 10 tracks of the conventional one. Is half the distance. Therefore, the head feed error is reduced to 1/2 of the conventional one, and the accuracy of the seek operation, that is, the position accuracy of the magnetic head 1 with respect to the track recorded on the magnetic disk 2 is further improved.

If the head carriage driving motor 8 is driven and controlled in the conventional manner using such a lead screw 12, it is necessary to double the rotational speed of the head carriage driving motor 8. However, when the lead screw 12 and the motor 8 for driving the head carriage are connected and driven via the gears 13 and 14, when the rotational frictional force of the lead screw 12 and the gears 13 and 14 is considered, the characteristics of the stepping motor are considered. There are many problems in doubling the rotation speed of the head carriage driving motor 8 because of insufficient upper torque and increased current consumption.

Therefore, in this embodiment, the pitch circle diameter and the number of teeth of the gear (second gear) 14 driven by the head carriage driving motor 8 are set to the gear (first gear) provided on the lead screw 12. Gear) 13 twice. That is, the pitch circle diameter of the gear 14 is φ10 mm as in the conventional case, and the pitch circle diameter of the gear 13 is φ5 mm. Therefore, the rotation ratio between the toothed wheels 13 and 14 is 1: 2.

As a result, when the gear 14 makes one revolution, the gear 13 makes two revolutions, and the rotation control of the head carriage drive motor 8 can be performed in the same manner as in the conventional art, so that it is not necessary to change the rotation speed and the torque is changed. Problems such as shortage and increase in current consumption can be solved.

Further, by setting the rotation ratio between the gear 13 on the lead screw 12 side and the gear 14 on the head carriage driving motor 8 side to 1: 2, the rotation speed of the head carriage driving motor 8 is changed to that of the conventional screw. It is possible to reduce the influence of the accumulated pitch error of the gears 13 and 14 by driving the lead screw 12 having a screw pitch of 1/2 with respect to the pitch p at a double speed.

When the rotation ratio between the gears 13 and 14 is set to 1: 2 in this way, the head feed error due to the effect of the accumulated pitch error in one rotation of the gear 13 is shown in the waveform diagram in FIG. It will fluctuate like. Therefore, the head feed error is reduced to about ± 5 μm at the peak.

In the above embodiment, the pitch circle diameter of the gear 13 is φ5 mm so that the rotation ratio between the gears 13 and 14 is 1: 2. However, the invention is not limited to this. The pitch diameter of the gear 14 may be 20 mm and the rotation ratio may be 1: 2 while keeping the circle diameter of 10 mm.

As a modification of the present invention, as shown in FIG. 4, three gears 15 to 17 may be interposed between the lead screw 12 and the head carriage driving motor 8. In the figure, a gear 15 is attached to the end of the lead screw 12, and a gear 17 is attached to the output shaft 8a of the head carriage drive motor 8. The gear 16 is interposed between the gear 15 and the gear 17, and meshes with both gears 15 and 17.

Therefore, the rotational driving force of the head carriage driving motor 8 is transmitted to the lead screw 12 via the gears 17, 16 and 15. The gears 17 and 16 have a pitch circle diameter of 10 mm, and the gear 15 has a pitch circle diameter of 5 mm. Therefore, the rotation ratio between the gears 17 and 16 is set to 1: 1 and the rotation ratio between the gears 16 and 15 is set to 2: 1. Therefore, the gear 15 provided on the lead screw 12 rotates twice while the gears 17 and 16 rotate once.

As a result, since the rotation control of the head carriage driving motor 8 can be performed in the same manner as in the conventional case, it is not necessary to change the rotation speed, and it is possible to solve the problems such as insufficient torque and increased current consumption.

Further, the gear 16 between the gears 15 and 17 separated from each other may be eliminated and the toothed belt may be wound around the gears 15 and 17.

In the above embodiment, the screw pitch P of the lead screw 12 is set to 1/2 of the conventional screw pitch p, and the rotation ratio of the gears 13 and 14 is set to 1: 2. However, not limited to this, for example, the screw pitch P of the lead screw 12 is set to 1/3 or 1/4 of the conventional screw pitch p, and the rotation ratio between the gears 13 and 14 is 1: 3 or. It may be set to be 1: 4. In that case, the magnetic head 1 moves a distance of 3.33 or 2.5 tracks while the lead screw 12 makes one rotation, and the moving distance of the magnetic head 1 per one rotation of the lead screw 12 is conventionally. The distance is 1/3 or 1/4 for 10 tracks.

[0039]

As described above, according to the first aspect of the present invention, the feed error of the magnetic head can be reduced by setting the screw pitch of the lead screw to p / n, and the gear on the lead screw side can be reduced. And the gear ratio on the side of the head carriage drive motor is set to 1: n, the screw pitch p can be adjusted without changing the rotation speed of the head carriage drive motor at the speed of driving the lead screw of the screw pitch p. The influence of the cumulative pitch error of the gear can be reduced by driving the lead screw of / n at the n-fold speed.

According to a second aspect of the present invention, the magnetic head moves within a range of 1 to 5 tracks in which magnetic recording is performed on the magnetic disk while the lead screw makes one rotation of the screw pitch p of the lead screw. By setting, the feed error of the magnetic head can be reduced, and the influence of the cumulative pitch error of the gear can be reduced. Also, the influence of backlash on the head positioning accuracy can be reduced.

[Brief description of drawings]

FIG. 1 is a plan view of a flexible magnetic disk device to which an embodiment of a head carriage driving mechanism according to the present invention is applied.

FIG. 2 is a front view showing a gear train of a head carriage drive mechanism.

FIG. 3 is a waveform diagram showing an influence of a cumulative pitch error on a head feed error.

FIG. 4 is a view showing a modified example of the present invention.

FIG. 5 is a diagram for explaining a conventional head carriage drive mechanism.

FIG. 6 is a waveform diagram showing a change in pitch circle error when a conventional gear is rotated.

FIG. 7 is a waveform diagram showing a change in head carriage feed error.

FIG. 8 is a waveform diagram in which a conventional head feed error and cumulative pitch error are combined.

[Explanation of symbols]

 1 Magnetic Head 8 Motor for Driving Head Carriage 11 Head Carriage Driving Mechanism 12 Lead Screws 13-17 Gears

Claims (2)

[Scope of utility model registration request] 1. A head carriage which supports a magnetic head and is slidable in a radial direction of a magnetic disk, a lead screw screwed on the head carriage and having a screw pitch p, and an output shaft of a head carriage driving motor. A plurality of gears that mesh with each other so as to transmit the rotation of the lead screw to the lead screw, a screw pitch of the lead screw is p / n, and a first gear that is axially attached to the lead screw. A head carriage driving mechanism having a rotation ratio of 1: n with a second gear mounted on the output shaft of the head carriage driving motor. 2. A head carriage slidably provided so that a magnetic head is slidably contacted in a radial direction of a magnetic disk to form a plurality of tracks on the magnetic disk in a concentric shape, and the head carriage is screwed to the head carriage. In a head carriage drive mechanism having a lead screw having a screw pitch p and a plurality of gears meshing so as to transmit the rotation of the output shaft of a head carriage drive motor to the lead screw, the screw pitch p of the lead screw is The magnetic head of the head carriage is magnetically recorded on the magnetic disk while the lead screw makes one revolution.
A head carriage drive mechanism configured to move within a track range.