JPH07163126A - Step motor for driving lens - Google Patents

Abstract

PURPOSE:To protect a lead screw against damage when a rotor is fixed to a stator case by securing a bearing for supporting a shaft at an end part thereof to the bottom face part of a motor body, making a hole larger than the outer diameter of the rotor core through the body cover, inserting the rotor into the hole and supporting the shaft. CONSTITUTION:A rotor core 11a comprising a permanent magnet is bonded through adhesive to a shaft 11b with lead screw thus forming a rotor. A stator stopper 12 is positioned with respect to a stator case (SC) 16 and a hole 12a larger than the outer diameter of the rotor core 11a for passing the rotor core 11a is made through a cover for confining stator cores 13a, 14a, 13c, 14c and coils 13b, 14b to the SC 16. A spring 17 fixed to a fixing part 16a on the outer periphery of the SC 16 urges the shaft 11b in the axial direction thus eliminating backlash. A bearing 15 supports the shaft 11b, being fixed to the joint of the stator cores 13c, 14c of the SC 16, at an end part thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor for driving a lens used in a photographing lens of a single lens reflex camera, a video camera or the like.

[0002]

2. Description of the Related Art FIG. 4 is an exploded perspective view of a conventional taking lens for a video camera. In FIG. 4, the entire stepping motor for driving the lens is indicated by reference numerals 31 and 32. The structure of these stepping motors will be described in more detail as shown in FIG. The configuration of the conventional stepping motor will be described below.

In FIG. 5, reference numeral 41a denotes a permanent magnet, the outer peripheral surface of which is multi-pole magnetized. This permanent magnet 4
A shaft 41b with a lead screw is fixed to 1a with an adhesive or the like to form a rotor 41. 43 and 44 are stator cores having a plurality of pole teeth arranged so as to surround the permanent magnet 41a, and the portions 43b and 44b of the stator cores 43 and 44 are wound around ring-shaped bobbins 43d and 44d. , The stator core 43,
It is a coil for generating magnetic poles at the portions 43a, 43c, 44a, 44c of 44. Further, 43e and 44e are stator cases for accommodating stator cores and coils made of metal, 45 is a bearing support member having bearings 45a and 45b for supporting the rotor 41, and 47
Is an urging spring for urging the rotor 41 in the axial direction to prevent backlash.

The stepping motor shown in FIG. 5 is a two-phase type PM stepping motor in which the bearing side phase is the A phase and the biasing spring side phase is the B phase.
For example, the A phase includes the stator core 43a and the stator core 4
3c, a coil 43b, a bobbin 43d for winding the coil,
It is composed of a stator case 43e.

Further, a plurality of pole teeth are formed on each of the stator cores 43a and 43c, and the respective stator cores are arranged so as to be meshed with each other so that the respective pole teeth engage with each other. Also, B
The phases are also composed of the same parts, and the parts are arranged in the same way.

Next, the positional relationship between the A-phase and the B-phase is such that the teeth are in a predetermined phase with each other.
There are notches in the stator cases 43e and 44e,
By fitting the protrusions provided on the stator cores 43c and 44a, respectively, a predetermined phase relationship is established.

Further, a plate made of a non-magnetic member is interposed between the stator cases 43e and 44e so that the magnetic paths of the respective phases do not influence each other.

[0008]

However, in the conventional example, when the bearing support member for supporting the bearing is attached to the stator case, the threaded portion of the shaft is inserted through the bearing 45a and incorporated, so that the threaded portion of the shaft is not damaged. And the characteristics of the motor may be deteriorated.

Further, in recent years, the lead screw is often processed by rolling, which has mass productivity, but in the case of a bar material having an outer diameter which is previously adjusted to the bearing diameter, the thread diameter after rolling is larger than the outer diameter. Therefore, post-processing for reducing the screw diameter, for example, centerless polishing or the like is required, resulting in a very high cost.

[0010]

Therefore, according to the present invention, a bearing for supporting the tip of the shaft is fixed to the bottom surface of the accommodating means, and a hole larger than the outer diameter of the rotor core is formed in the lid attached to the accommodating means. The rotor is opened and the rotor (specifically, the rotor core and the shaft with the lead screw) is inserted through the hole to support the rotor. Further, the bearing that supports the tip of the rotor is fixed to the lens barrel on which the stepping motor of the present invention is mounted.

[0011]

EXAMPLES Next, examples of the present invention will be described. Figure 1
It is an exploded perspective view of a stepping motor of the present invention. Figure 1
11a is a rotor core made of a permanent magnet, and 11b is a shaft with a lead screw. These two parts are fixed with an adhesive, etc., and the output shaft (rotor)
To form. Further, 13a, 14a, 13c, 14c are stator cores having a plurality of pole teeth, and 13b, 14
Reference numeral b is a coil wound around a bobbin, and 16 is a stator core 13a, 14a, 13c, 14c and the coil 13
b, 14b is a stator case for accommodating b, 14 is positioned and attached to the stator case 16,
The stator cores 13a, 14a, 13c, 14c and the coils 13b, 14b are stator retainers that are lids for preventing the coils from coming out of the stator case 16.
A hole 12a larger than the outer diameter of the rotor core 11a is formed so that 1a can pass through. Further, 17 is an urging spring that urges the shaft 11b in the axial direction by removing the play by attaching it to a mounting portion 16a provided on the outer peripheral portion of the stator case 16, and 15 is a stator core 13c, 14c of the stator case 16. Shaft 11 to be attached to the joint
It is a bearing which supports the terminal part of b.

FIG. 2 is a perspective view in which a part of the stator case 16 is cut out so that the inside can be seen. Figure 2
In the figure, 16a is a hole for press-fitting and supporting the bearing 15. 16b and 16c are the stator 13c,
14c is an elastically deformable portion that comes into contact with 14c and urges the entire stator in the axial direction.

Next, a case where the above stepping motor is used as a lens driving device will be described. Figure 3
FIG. 6 is an exploded perspective view of the case where the stepping motor of the present invention is used as a taking lens of a video camera. In FIG. 3, reference numeral 200 denotes a V holding frame that holds a variator lens group for changing the angle of view, and 400 holds an RR lens group that has a focus position change associated with a change in the view angle and a focusing function. It is an RR holding frame. The V holding frame 200 can be moved in the optical axis direction by the two guide bars 206 and 207, and the RR holding frame 400 can be moved in the optical axis direction by the two guide bars 415 and 416. The V holding frame 200 will be described in detail. The guide bars 206 and 207 are the variator lens group and the R
It is provided in parallel with the optical axis of the R lens group, the other end of each is fixed to the lens barrel 100, and the other end of each is fixed to the lens barrel 300. Further, the guide bar 206 is fitted with the sleeve 202d of the V holding frame 200, and the guide bar 207 is fitted with the U-shaped groove 202e of the V holding frame 200. 200 is movable in the optical axis direction.

Reference numeral 209 is a stepping motor of the present invention. The interlocking portion between this and the V holding frame 200 will be described below. First, the output shaft 209b is inserted into the motor body through a hole larger than the outer diameter of the rotor core provided in the stator holder (lid) (not shown). Then, after the output shaft 209b is held in the rack 208, the bearing 22
2 is assembled so that the tip of the output shaft is supported. The output shaft 209b is threaded with a predetermined lead,
Since this and the rack 208 attached to the V holding frame 200 engage with each other, the V holding frame 200 is moved in the optical axis direction as the output shaft 209b rotates. At this time, the tip portion 209c of the output shaft 209b is supported by the bearing 222 fixed to the lens barrel 100. The motor body 209a is fixed to the lens barrel 300 with screws or the like. Further, regarding the RR holding frame 400, the V holding frame 20
Since the structure is the same as 0, the description is omitted. Further, in this embodiment, the elastically deforming portion for urging the stator core is provided in the stator case, but it may be provided in the stator retainer.

[0015]

As described above, according to the present invention, the bearing for supporting the end portion of the shaft is fixed to the bottom surface of the motor body, and a hole larger than the outer diameter of the rotor core is formed in the lid of the body. Since the rotor (the rotor core and the shaft with the lead screw) is inserted through the hole to support the shaft, it is not necessary to pierce the shaft with the threaded part to assemble the bearing as in conventional motors. It will not damage the motor performance due to scratches.

Further, when the lead screw is processed, the shaft diameter suitable for the bearing can be manufactured by the rolling process, and the subsequent finishing process only needs to be uniformly ground on the entire shaft, which reduces the cost of the shaft. Made possible.

Further, in the case of the stepping motor of the present invention, since the rotor portion can be easily removed, various stepping motors can be obtained by simply changing the length of the rotor, which is extremely versatile.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of an embodiment of a stepping motor of the present invention.

FIG. 2 is a perspective view for clearly showing the inside of a stator case of a stepping motor.

FIG. 3 is an exploded perspective view showing a state in which a stepping motor is incorporated in a lens barrel.

FIG. 4 is an exploded perspective view of a conventional stepping motor incorporated in a lens barrel.

FIG. 5 is a cross-sectional view of a conventional stepping motor.

[Explanation of Codes] 11a Rotor magnet 11b Shaft with lead screw 12 Lids 13a, 14a, 13c, 14c Stator 15 First bearing 16 Storage means 17 Energizing spring

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 17, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 5]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location G03B 3/10 13/34 H02K 37/24 Q 9180-5H

Claims (4)

[Claims] 1. A rotor core made of a permanent magnet, a shaft with lead screws, a stator core having a plurality of pole teeth, a coil wound around a bobbin, and a coil wound around the stator core and the bobbin. The contact surface between the accommodating means and the stator core of the accommodating means serves as an opening, the other surface of the accommodating means serves as a joint surface with the stator core, and the shaft fixed to the bearing accommodating portion provided on the joint surface A bearing for supporting the distal end portion, a lid fixed to the opening by a positioning means and a supporting means provided in the accommodating means, a mounting portion provided on the outer peripheral surface of the accommodating means, and the mounting portion being mounted to the mounting portion, A lens driving stepping motor having an urging spring for urging the shaft in the axial direction to remove play. 2. The lens driving stepping motor according to claim 1, wherein a hole larger than an outer diameter of the rotor core is formed in the lid, and the rotor core is inserted through the hole so that the shaft serves as the bearing. A stepping motor for driving a lens, characterized in that the stepping motor is supported by. 3. The lens driving stepping motor according to claim 1, wherein the bearing that supports the tip of the shaft is provided in a lens barrel to which the stepping motor is attached. . 4. The lens driving stepping motor according to claim 1, wherein the lid or the accommodating means has an elastically deforming portion for urging the stator core to eliminate rattling of the stator core. Stepping motor.