JPH0159673B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic head positioning device for a floppy disk. In particular, the step error in the threaded engagement between the lead shaft of the magnetic head positioner and the threaded part of the rotor part of the magnetic head positioner is made movable via the lead screw shaft that is moved by a drive motor, and the overall step accuracy is achieved. This invention relates to a mechanism for attaching a lead screw shaft to a head carriage, which is devised to maintain improved performance.

The configuration of a conventionally used magnetic head positioner will be outlined. Figure 1 of the attached drawings is a schematic plan view of a conventional magnetic head positioner, with frame 3
A drive motor M is attached to the arm portion 32 provided at the head 0, and the end connecting portion 17 of the lead screw shaft C, which is movable in a linear direction by this motor, extends and is rigidly fixed to the protruding arm 36 of the head carriage 34. be done. The head carriage 34 is the magnetic head 4
0 is installed, and the frame 30
The guide shaft 42 is provided so as to be able to fit and slide freely. Further, a spring 45 installed between the frame 30 and the carriage arm 36
Since the magnetic head carriage 34 is biased in the direction of the frame, the magnetic head carriage 34 is normally disposed at a position moved in the same direction as the biasing direction.

Next, the outline of the motor M used in the magnetic head positioner and the linear step actuator operated by this motor will be explained.

In FIG. 7, the bearing part a consists of ball bearings 8 and 10 supported respectively between the mounting plate 2 and the rotor b, which will be described later, and between the spacer 6 provided inside the cover 4 and the rotor b. is made of a synthetic resin material such as plastic that is integrally formed with the magnet part 12, and has a female thread 1 in the center.
4 will be provided. The reason why plastic material is used for the rotor b is to reduce the wear of both related members caused by the sliding of the screw shaft c, and to reduce the coefficient of friction. However, in the present invention, it is optimal to use polyacetal containing carbon fiber for the rotor b.

The male threaded portion 16 formed on the lead screw shaft c is configured to be screwed together with the female threaded portion 14 of the rotor b and to be able to freely reciprocate within the cavity 18 inside the rotor b, thereby maintaining high pitch accuracy and facilitating mass production. It is recommended to cut free-cutting brass (JISC3604BD) using an NC lathe, etc. in consideration of its properties. Furthermore, in consideration of abrasion with the plastic material of the rotor b, surface treatment with Teflon or the like may be applied. Further, a carriage of a head positioner or the like is connected to the portion of the lead screw shaft c where the external thread is not formed, that is, the end of the connecting shaft portion 17, as will be described later.

The stator section d is mounted between the mounting plate 2 and the cover 4 on the outside of the rotor magnet 12, and consists of two pairs of magnetic pole plates 20, 22 and 20, 22, each housing a coil 24, 26 therein. . However, by inputting one rectangular wave voltage pulse to this stator portion d, the rotor b is rotated at a predetermined angle, for example, 15°.
It is configured to be rotatable.

Next, step accuracy, step error, and shaft rigidity will be explained in relation to the invention of the present application.

The most important basic performance of the screw shaft shown in this drawing is step accuracy. Now, if we drive the rotor as one unit of rotation, the theoretical position X(n) of the screw shaft with n steps is X(n)=/360×P×n P: Lead screw pitch Actual If the position is x(n), then E(n)=x(n)-X(n), and this is called a step error. Further, the difference R between the maximum value and the minimum value of E(n) is called step accuracy. If you graph the relationship between step error and step accuracy R, please refer to attached No. 9.
The state shown in the figure is reached. If the screwing state of the female thread and the male thread is ideal (see FIG. 10), screw feeding is performed with step accuracy R=0. However, it is technically impossible to mount the rotor female thread and the shaft male thread completely coaxially. Therefore, as shown in FIG. 11, if the female thread and the male thread are installed with coaxiality Δy/2, a step error of Δx=Δy×tanθ/2 will occur during one rotation.

In this way, if the installation coaxiality of the rotor and screw shaft is △y/2, during one rotation of the rotor, △x
A step error occurs. In order to reduce this error, it is important to maintain the stiffness of the screwshaft at an appropriate value. As a method for this, there is also a method of forming the connecting shaft portion 17 of the screw shaft to be thin or using a tight spring in the connecting portion to maintain an appropriate value of rigidity.

The present invention differs from the above-mentioned method in that it adds an ingenuity to the structure for attaching the screw shaft to the magnetic head carriage to reduce stepping errors and improve overall stepping accuracy, regardless of the rigidity of the screw shaft. It is something.

The present invention provides a configuration in which the curved surface of the detent provided at the tip of the connecting shaft can freely slide into contact with the slope of the bush for attaching the connecting shaft to the head carriage. It is.

An embodiment of the present invention will be described below based on the accompanying drawings. The connecting shaft portion 17 extends and the head carriage 34
penetrates the bushing 44 fitted to the protruding arm 36 of the
A detent 46 having a protruding arm 48 on one side is screwed 50 onto its end. An appropriate gap 52 is provided between the bush 44 and the connecting shaft portion 17. An inclined surface 54 is formed on the upper surface of the bushing 44 to form an appropriate angle θ, and a portion 56 of the lower surface of the detent 46 facing the inclined surface of the bushing is formed into a spherical shape having an appropriate angle. However, the spherical shape of the detent 46 and the inclined surface 54 of the bush 44 face each other, and both surfaces can freely slide. The protruding arm 48 of the detent 46 is the protruding arm 3 of the head carriage.
U-shaped portion 60 of the U-shaped guide 58 installed upright at 6
is inserted into.

Next, the effects of the present invention will be explained.

When the motor M operates, the threaded portion meshing with the female thread 14 of the rotor b and the male thread 16 of the linear actuator c moves the linear actuator c back and forth together with the connecting shaft portion 17 due to the operation of the rotor b. When the head carriage 34 is moved, the head carriage 34 moves in the same direction via the protruding arm 36 to which the connecting shaft portion 17 is attached. The spherical lower surface 56 of the detent 46, which is in contact with the inclined surface 54 of the bushing 44, can freely slide relative to each other. Of course, the elastic action of the spring 45 installed on the protruding arm 36 and the frame 30 is applied to the inclined surface 54.
It serves to maintain proper contact between the lower surface 56 of the sphere and the lower surface 56 of the sphere. The gap 52 provided between the bush 44 and the connecting shaft portion 17 is within the range of the size of the gap.
The spherical lower surface 5 of the detent 46 allows free tilting of the
8 also becomes slidable while contacting the inclined surface 54 of the bush 44 in response to the tilting of the connecting shaft portion.

Due to the free sliding between the curved surface of the detent 46 and the inclined surface 54 of the bushing 44, the connecting shaft portion 17
The step error in the screw engagement between the female thread 16 of the linear actuator c and the male thread 14 of the rotor b is corrected, and the almost ideal meshing state of both threaded parts is maintained, improving overall accuracy. Helpful. Therefore, by driving the motor, the head carriage 34, which is movable while being fitted onto the guide shaft 42, is accurately moved at a predetermined position via the connecting shaft portion 17, the detent 46, the bush 44, and the protruding arm 36. Therefore, the accuracy of the magnetic head positioner can be improved. Also, unlike this embodiment, the upper surface of the bushing may be formed into a sphere, and the sphere may be provided with a detent having a curved inclined surface to achieve the same effect as in the previous embodiment.

[Brief explanation of drawings]

FIG. 1 is a schematic plan view of a conventional magnetic head positioner. FIG. 2 is a schematic plan view of the positioner according to the present invention. FIG. 3 is an enlarged sectional view showing a state in which the connecting shaft portion is attached to the protruding arm of the head carriage. FIG. 4 is an enlarged side view of the detent. Figure 5 is an enlarged sectional view of the bush. FIG. 6 is an enlarged plan view and side view of the guide.
FIG. 7 is an enlarged sectional view showing the state in which the drive motor and the connecting shaft are attached to the head carriage according to the present invention. FIG. 8 is an enlarged plan view of the detent and guide seen from the X direction in FIG. 2. FIG. 9 is a graph showing the relationship between step error and step accuracy. FIG. 10 is a schematic diagram showing an ideal screwed state of screws. FIG. 11 is a schematic diagram showing step error. 17... Connection shaft section, 30... Frame, 34...
... Head carriage, 36 ... Projection arm, 44 ... Guide bush, 45 ... Spring, 46 ... Stop rotation, 52 ... Gap, 54 ... Inclined surface, 56 ...
...Spherical curved surface, 58...Guide.

Claims (1)

[Scope of Claims] 1. In a magnetic head positioner having a magnetic head carriage connected to a connecting shaft of a screw shaft that is threadedly engaged with a threaded portion of a rotor portion and is movable in a straight line, an end of the connecting shaft of the screw shaft. and a guide bushing provided on a part of the carriage and provided with an inclined surface, and the curved surface or the inclined surface can freely slide relative to each other by the operation of the connecting shaft portion. A magnetic head positioner featuring: 2. The magnetic head positioner according to claim 1, wherein an elastic body is installed between the projecting arm of the head carriage and the frame to urge the projecting arm toward the frame.