JPS6255022B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a carriage drive device in a magnetic storage device using a magnetic recording medium such as a flexible disk generally called a floppy disk.

For example, the head carriage drive device of a floppy disk device is generally configured to feed the head carriage in a linear direction by rotating a screw shaft, but backlash may occur due to play between the screw shaft and the head carriage. Since tracking deviation occurs, a means for removing this backlash is required.

FIG. 1 shows a conventional example of a head carriage for a double-sided drive of a flexible disk (hereinafter simply referred to as a "disk"). It has an upper head 5 that contacts the upper surface. The lower head 4 is fixed to one end 6a side of the carriage main body 6, and the upper head 5 is near the free end of a movable arm 8 rotatably supported on the other end 6b side of the carriage main body 6 via a leaf spring 7. It is attached to and is biased in the direction of arrow A by a spring 9.

One end 6a of the carriage main body 6 is provided with a female screw hole, and the other end 6b is provided with a screw shaft insertion hole, into which a screw shaft 11 directly connected to a step motor 10 is inserted and screwed. Therefore, when the screw shaft 11 is rotated by the step motor 10, the entire carriage 1 is rotated.
It is linearly fed in the direction of arrow B while being supported by a guide shaft (not shown) provided parallel to the screw shaft 11.

In order to eliminate backlash at that time, a collar 12 is attached which is screwed onto the screw shaft 11 and is slidable in the axial direction of the screw shaft 11, and a compression spring 13 is interposed between the collar 12 and the carriage body 6. In addition to applying force in the axial direction, a rotation stopper 14 was provided.

With such a conventional head carriage structure, the work of assembling the carriage to the screw shaft was difficult and required many man-hours, resulting in high costs.

The present invention has been made in view of the above points, and an object of the present invention is to provide a carriage drive device that is easy to assemble to a screw shaft and that can reliably remove backlashes.

Therefore, in the carriage drive device according to the present invention, the half nut is attached to the leaf spring, and the angle formed by the side wall surfaces of the screw groove that engages with the screw shaft is larger than the angle formed by the side wall surfaces of the screw thread having a predetermined width at the top of the screw shaft. The screw shaft is always pressed against the screw shaft by the screw shaft and attached to the carriage, and the rotation of the screw shaft is converted into linear motion by the half nut.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 2 and 3. The same parts as in the conventional example shown in FIG.

The carriage body 16 in FIG. 2 is provided with a simple screw shaft insertion hole at both ends 16a and 16b, and is supported so that the screw shaft 11 can be inserted therethrough and slid in the direction of arrow B. Just Screwshaft 11
are not directly screwed together.

A leaf spring 18 having a half nut 17 fixed to the tip thereof, which engages with the screw shaft 16, is attached to the end 16b of the carriage body remote from the lower head 4, and a leaf spring 18 is attached to the end 16b of the cartridge body, which is located away from the lower head 4. Each proximal end of the leaf spring 19 to be biased is attached and fixed by a screw 20 and a leaf nut 21. A protrusion 17a is provided at a portion of the half nut 17 that comes into contact with the leaf spring 19, so that the pressing force of the leaf spring 19 acts effectively.

In addition, as shown in FIG. 3, the half nut 17
The angle θ _S formed by both side wall surfaces of the thread groove 17b is made larger than the angle θ _N formed by the both side wall surfaces of the screw thread 11b having a predetermined width at the top of the screw shaft 11.

With this configuration, when the screw shaft 11 is rotated by the step motor 10, the half nut 17 that engages with it moves linearly in the direction of arrow B, which is transmitted to the carriage body 16 via the leaf spring 18. As a result, the entire head carriage 1 moves in the direction of arrow B. That is, the rotation of the screw shaft 11 is converted by the half nut 17 into a linear motion of the head carriage 1.

Moreover, as is clear from FIG. 3, at this time, the middle portions of both side surfaces of the thread groove 17b of the half nut 17 come into contact with the thread 11b of the screw shaft 11, so that play is absorbed and no breakage occurs.

Furthermore, with this structure, when assembling the head carriage 1 to the screw shaft 11, the leaf springs 18 and 19 are pushed down and the screw shaft 11 is inserted into the insertion hole provided in the carriage body 16. Since only one piece is required, the number of assembly steps can be significantly reduced, which greatly contributes to cost reduction.

Note that the half nut 1 is
It is also possible to omit the leaf spring 19 so as to serve both of attaching the screw shaft 7 and applying a pressing force to the screw shaft 11.

Furthermore, as in the embodiment shown in FIG. 2, by fixing the plate spring 18, which is the attachment member of the half nut 17 to the carriage body 16, at a position sufficiently distant from the magnetic head, for example, the lower head 4,
The positional accuracy of the head against temperature changes is also improved.

Next, the reason will be explained. In FIGS. 1 and 2, a is the distance between the spindle 2 and the step motor 10, both of which are fixed to an aluminum frame (not shown).

In b, spindle 2 and disk 3 are lower head 4
is the distance between the gap and the contact point,
Between this is the polyester film of disk 3.

_c1 is the distance between the step motor 10 and the position where the spring 13 of the carriage body is locked, and the screw shaft 11 is made of stainless steel.

c ₂ is the distance between the step motor 10 and the half nut 17;
It is made of stainless steel.

d ₁ is the locking position of the spring 13 and the lower head 4
This is the distance between the gap and the resin of the carriage body 6.

d ₂ is the distance between the fixed position of the leaf spring 18 and the gap of the lower head 4, which is also the distance between the resin of the carriage body 16.

e is the distance between the center of the half nut 17 and the fixed position of the leaf spring 18;
It is made of stainless steel.

Here, aluminum, polyester, stainless steel,
The linear expansion coefficients of the resin are α, β, γ, and θ, respectively.

If the positional deviation of the lower head ₄ due to the temperature change _Δt in the case of the head carriage of _the conventional mechanism _shown in FIG. .

If the positional deviation of the lower _head 4 due to the temperature change _Δt in the embodiment of _the present invention shown in FIG _.
...(2) becomes. From equations (1) and (2), δ ₁ - δ ₂ = {-γ(c ₁ - c ₂ +e) + θ(d ₂ -
d ₁ )}Δt...(3) Here, as is clear from Figures 1 and 2,
c ₁ −c ₂ +e=d ₂ −d ₁ .

Therefore, equation (3) can be expressed as follows.

δ ₁ - δ ₂ = {(d ₂ - _{d 1} ) (θ - γ)} Δt ... (4) Here, d ₂ - _{d 1} > 0, and the linear expansion coefficient θ of the resin is the linear expansion coefficient of stainless steel. Since it is larger than the coefficient γ, θ
−γ>0.

Therefore, since the right side of equation (4) is positive, δ ₁ −
δ ₂ >0, and δ ₂ <δ ₁ .

That is, the positional deviation δ ₂ in the embodiment of the present invention (FIG. 2) is smaller than the positional deviation δ ₁ in the conventional case (FIG. 1). Also, the larger d ₂ is, the more
That is, the leaf spring 1 to which the half nut 17 is attached
Since d ₂ -d ₁ becomes larger as the fixed position of the lower head 8 is moved away from the lower head 4, δ ₁ -δ ₂ becomes larger, and the amount of positional deviation of the lower head due to temperature changes can be reduced.

As described above with respect to the embodiments, the carriage drive device according to the present invention can completely prevent backlash during linear feed, and furthermore, the work of assembling the carriage to the screw shaft is extremely simple.

Furthermore, in the embodiment shown in FIG. 2, by fixing the half nut to the carriage at a position sufficiently distant from the head, the positional accuracy of the head against temperature changes can be greatly improved.

Furthermore, the present invention is applicable to magnetic disks other than flexible disks, head carriages for drives such as magnetic sheets, head carriages that perform photoelectric or electrostatic recording/reproduction, and even printer carriages, etc. The same applies to drives for linearly fed carriages.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of a conventional carriage and its drive device, FIG. 2 is a schematic configuration diagram similar to FIG. 1 showing an embodiment of the present invention, and FIG.
FIG. 3 is an enlarged cross-sectional explanatory view showing the relationship between the thread groove of the half nut and the thread of the screw shaft. 1...Head cartridge, 2...Spindle,
3... Flexible disk, 4... Lower head, 5... Upper head, 6, 16... Carriage body, 8... Movable arm, 10... Step motor, 11... Screw shaft, 12... Collar, 17... ...half nut, 18, 19... leaf spring.

Claims (1)

[Claims] 1 In a carriage drive device that sends a carriage in a linear direction by rotating a screw shaft,
A half nut is always attached to the screw shaft by a leaf spring, and the angle formed by the side walls of the screw groove that engages with the screw shaft is larger than the angle formed by the side walls of the screw thread having a predetermined width at the top of the screw shaft. A carriage drive device, characterized in that it is attached to a carriage while being urged to press against it, and the rotation of the screw shaft is converted into linear motion by the half nut.