JPH06272746A - Drive device - Google Patents

Abstract

PURPOSE:To provide a drive device whose manufacturing cost is low, and which facilitates a lead change and has good driving accuracy. CONSTITUTION:A lead screw is formed with a male threaded part on its outer periphery, and can be rotated around its axial line. An electric motor 18 is installed to drive the rotation of the lead screw 12. A traveling element 20 is formed with a female threaded part which can be screwed in the lead screw 12, and travels along the lead screw 12 when the lead screw 12 is rotatingly- driven by the electric motor 18. The lead screw 12 is composed of a lengthwise and columnar shaft part 22, and the first long-size coil spring 24 which is fitted onto the outer periphery of the shaft part 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive device, and more particularly to a drive device using a lead screw.

[0002]

2. Description of the Related Art A conventional drive device using a lead screw will be described. The drive device has a male screw portion formed on the outer peripheral surface thereof and is rotatable about an axis and drive means for rotating the lead screw. And a moving body that has a female screw portion that can be screwed into the lead screw and that moves along the lead screw when the lead screw is rotationally driven by the drive means.
The male screw portion of the lead screw is formed by cutting the outer peripheral surface of the columnar body with a die or a die head as an example of manufacturing, and the female screw portion of the moving body is provided with a through hole in the moving body once as an example of manufacturing. The inner peripheral surface of the through hole is formed by cutting with a tap. With this configuration, for example, when a lens of a camera, a VTR, or the like is driven, the lens can be moved along the lead screw by attaching the lens to the moving body and operating the driving means to rotate the lead screw.

[0003]

However, the above-mentioned conventional drive device has the following problems. Since the male screw part of the lead screw and the female screw part of the moving body used in the drive device are formed by cutting or rolling using a die or a tap, it takes time to manufacture the drive device and the manufacturing cost is high. To rise. In addition, when changing the lead (moving distance of the moving body when the lead screw makes one rotation), it is necessary to prepare a new lead screw and moving body again and perform cutting using a die or tap again. Yes, it takes time and cost to manufacture. Also,
Since the lead angle changes depending on the diameter of the lead screw, there is a problem that a lead screw having a large lead in spite of the diameter is prone to manufacturing errors and the driving accuracy of the driving device is lowered. Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide a driving device which has a low manufacturing cost, is easy to change leads, and has high driving accuracy.

[0004]

The present invention has the following constitution in order to achieve the above object. That is, a male screw portion is formed on the outer peripheral surface, and has a lead screw rotatable about an axis, a drive means for rotating the lead screw, and a female screw portion screwable to the lead screw. When the screw is driven to rotate by the driving means, in a driving device comprising a moving body that moves along the lead screw, the lead screw is a long shaft-shaped shaft portion, It is characterized by comprising a long first coil spring fitted onto the outer peripheral surface of the shaft portion so as to form the male screw portion. In addition, the female thread portion may be formed by using a second coil spring whose thread formed on the inner circumference thereof can be screwed into the first coil spring. Further, it is better to provide an adjusting mechanism for adjusting the inner diameter of the second coil spring.

[0005]

When the lead screw is composed of the shaft portion formed in the shape of a long column and the long first coil spring externally fitted on the outer peripheral surface of the shaft portion, it is possible to perform cutting work or rolling. Since a uniform male screw part is formed on the outer peripheral surface of the shaft part according to the cross-sectional shape of the wire used for the first coil spring without performing a manufacturing operation, it can be screwed into the lead screw. When the moving body having the female screw portion is screwed onto the lead screw, the moving body can be moved along the lead screw rotated by the driving means. Further, when the female screw portion of the moving body is formed by using the second coil spring, the female screw portion having a uniform screw thread according to the cross-sectional shape of the wire is formed on the inner circumference without performing cutting work or rolling work. Can be formed. Also, for the second coil spring,
When the adjusting mechanism for adjusting the inner diameter is provided, it is possible to reduce the backlash when meshing with the first coil spring and improve the driving accuracy.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a partially cutaway front view of a drive device according to the present invention. FIG. 2 is a cross-sectional view of essential parts showing the structures of the male screw portion of the lead screw and the female screw portion of the moving body in FIG. FIG. 3 is a cross-sectional view taken along the line AA showing the adjustment mechanism of FIG. FIG. 4 is a cross-sectional view taken along line AA showing another embodiment of the female screw portion of the moving body.

First, the structure of the drive unit 10 will be described with reference to FIGS. 1 and 2. The drive device 10 includes a lead screw 12 having a male screw portion formed on an outer peripheral surface thereof, a base 14 that rotatably supports the lead screw 12 around its axis, and a base 1 that is parallel to the lead screw 12.
4, a guide 16 for moving the lead rod 12 while preventing rotation of a moving body, which will be described later, and a guide 16 attached to the side of the base 14 and connected to the lead screw 12. An electric motor 18 that is an example of a driving unit that rotationally drives
The moving body 20 is screwed onto the lead screw 12.

Each configuration will be described in more detail. The lead screw 12 is a long cylindrical first coil spring that is fitted onto the outer peripheral surface of the shaft body 22 so as to form a long cylindrical body 22 and a male screw part. Two
It consists of 4 and. The first coil spring 24 is formed as a close contact spring (a spring in which adjacent turn parts are in close contact with each other in a normal state in which no external force is applied) by using a single wire having a constant diameter. Inner diameter is shaft part 2
The diameter is slightly smaller than the outer diameter of 2. Therefore, the first coil spring 24 is fitted into the shaft body portion 22 in a state where the first coil spring 24 is loosened by applying an external force so that the inner diameter of the first coil spring 24 becomes larger than the outer diameter of the shaft body portion 22. It is externally fitted to the shaft portion 22 so as to be in close contact (see FIG. 2). In addition, instead of the first coil spring 24, the shaft body portion 22
Alternatively, the wire rod may be directly wound around to form the male screw portion. Further, since the male screw portion on the outer peripheral surface of the shaft body portion 22 is formed by the wire rod spirally wound, the shaft body portion 2
If 2 is replaced by a cylinder instead of a polygonal prism, the outer circumference of the male screw portion is formed into a substantially circular shape, and can be used as a lead screw.
As an example, the base 14 is formed of a rectangular plate material, and both ends (left and right ends in FIG. 1) thereof are bent into an L shape to have a U-shaped cross section.

The movable body 20 is provided with a through hole 26 through which the guide 16 can penetrate and a second coil spring 28 as a female screw portion that can be screwed into the male screw portion of the lead screw 12, and the through hole 26 The guide 16 is inserted, and the second coil spring 28 is screwed and attached to the lead screw 12. The second coil spring 28 is formed in a cylindrical shape by using a wire material having the same diameter as the wire material forming the first coil spring 24, and a shaft body portion for forming a male screw part of the lead screw 12 is formed. First coil spring 24 fitted onto 22
It is formed with an inner diameter that can be screwed. In the present embodiment, the second coil spring 28 is used as the female screw portion, but a normal female screw formed by cutting using a tap may be used instead.

Next, the operation will be described with reference to FIG. 1. When the electric motor 18 operates and the lead screw 12 rotates, the first coil spring 24 and the second coil spring 28 screwed together are provided, and the guide is provided. 1
The moving body 20 prevented from rotating by 6 is in the axial direction of the first coil spring 24 (left-right direction in FIG. 1).
Of the lead screw 12, the lead screw 12 moves leftward or rightward. Accordingly, if a lens used in, for example, a camera or a VTR is attached to the moving body 20, the lens can be driven in a predetermined direction for a predetermined distance.

Further, FIG. 3 shows a second coil spring 28.
An example of the adjusting mechanism 30 for adjusting the inner diameter of the is shown. The adjusting mechanism 30 includes a pair of plate bodies 32 and 34 attached to each end of the second coil spring 28 and a pair of plate bodies 32 and 3.
4 and the adjusting screw 36 mounted between them.
A female screw that is screwed into the adjusting screw 36 is formed on one of the plate bodies 32. By rotating the adjusting screw 36, the distance between the end portions of the second coil spring 28 is changed, and the second screw spring 28 is changed.
Coil spring 28 is unwound or tightened. As a result, the diameter of the second coil spring 28 can be increased or decreased to adjust the inner diameter of the second coil spring 28. This adjusting mechanism 30 is used for the moving body 20.
When it is provided, it is possible to adjust the meshing state of the first coil spring 24 and the second coil spring 28, and it is possible to perform highly accurate driving with little backlash.

FIG. 4 shows another embodiment of the second coil spring. This second coil spring 38
Is formed in a square tube shape (in this embodiment, a square tube shape as an example) instead of the above-mentioned cylindrical shape. When the second coil spring 38 is formed in a rectangular tube shape, the cylindrical first
Since the contact area with the coil spring 24 is reduced, the frictional resistance is also reduced, the rotational force applied to the lead screw 12 can be reduced, and the electric motor 18 can be downsized. Further, the moving body 20 can be moved at high speed as the frictional resistance is reduced due to the reduction of the contact area. Also,
In the drive device having the above-described configuration, the male screw portion of the lead screw and the female screw portion of the moving body are formed by using the coil spring, so that the lead can be easily changed only by changing the coil spring. In addition, when forming the male screw part on the lead screw, it is only necessary to fit the coil spring on the outside, and it is possible to manufacture a lead screw with a large lead in spite of its diameter with high accuracy and in a short time. Can be realized.

Although various preferred embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments, and a coil spring formed by using a wire rod having a triangular or rhombic cross section. May be used to change the shape of the threads of the male screw portion and the female screw portion. In addition, the first coil spring and the second coil spring externally fitted to the lead screw may be plated to reduce frictional resistance and improve rust prevention. Of course, many modifications can be made.

[0014]

When the drive device according to the present invention is used, a uniform male screw portion corresponding to the cross-sectional shape of the wire used in the first coil spring is formed on the outer peripheral surface of the shaft portion of the lead screw. Since it can be formed without performing cutting work or rolling work, it is possible to reduce the manufacturing time and the manufacturing cost of the drive device. Further, since cutting work and rolling work are unnecessary, it is possible to accurately manufacture a lead screw having a large lead in spite of the diameter, so that driving accuracy can be improved. In addition, a lead screw having different leads can be easily manufactured only by replacing the first coil spring. Further, when the female screw portion of the moving body is formed by using the second coil spring, the female screw portion having a uniform screw thread according to the cross-sectional shape of the wire is formed on the inner circumference without performing cutting work or rolling work. Since it can be formed, it is possible to further reduce the manufacturing time of the drive device and the manufacturing cost. Further, when the second coil spring is provided with the adjusting mechanism for adjusting the inner diameter, it becomes possible to reduce the play at the time of meshing with the first coil spring, and the driving accuracy is improved.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a drive device according to the present invention.

FIG. 2 is a cross-sectional view of essential parts showing structures of a male screw portion of the lead screw and a female screw portion of the moving body in FIG.

3 is a cross-sectional view taken along the line AA showing the adjustment mechanism of FIG.

FIG. 4 is a cross-sectional view taken along the line AA showing another example of the female screw portion of the moving body.

[Explanation of symbols]

 10 Drive device 12 Lead screw 18 Electric motor 20 Moving body 22 Shaft body portion 24 First coil spring

Claims (3)

[Claims] 1. A male screw portion is formed on an outer peripheral surface of the lead screw, the lead screw rotatable around an axis, a driving means for rotationally driving the lead screw, and a female screw portion screwable to the lead screw. A driving device comprising a moving body that moves along the lead screw when the lead screw is rotationally driven by the driving means, wherein the lead screw has a long columnar shaft body. And a long first coil spring externally fitted on the outer peripheral surface of the shaft portion so as to form the male screw portion. 2. The internal thread of the female threaded portion is formed by using a second coil spring that can be screwed into the first coil spring. 1. The drive device according to 1. 3. The drive device according to claim 2, wherein the second coil spring is provided with an adjusting mechanism for adjusting an inner diameter.