JPH0693056B2 - Camera motor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a motor for a camera used for autofocus in a video camera or the like, and particularly to a motor for a camera most suitable for zone autofocus of a single focus lens. .

[Outline of Invention]

The present invention relates to an n-phase coil and a 36-phase coil for a camera motor used for autofocus in a video camera or the like.
By arranging (n-1) movable magnets so that n rotation stop positions obtained by dividing the rotation angle of 0 ° / n into (n-1) absolutely correspond, This is a camera motor optimized for zone autofocus.

[Conventional technology]

Conventionally, in a video camera, a 6 × zoom lens is often used as an imaging lens, and a brush motor with a reduction gear is used to drive the autofocusing mechanism.

In the camera motor using the brush motor with the reduction gear, the reliability of the mechanical portion such as the reduction gear and the brush,
The response is low, and it is difficult to reduce the size and power consumption of the camera.

[Problems to be solved by the invention]

Conventionally, various camera motors have been proposed in order to solve the above-mentioned problems, but there are still problems in weight, size, power consumption, cost, etc. It couldn't be realized.

Therefore, in view of the above-mentioned conventional problems, the present invention provides a motor for a camera having a novel structure that does not cause a problem with respect to weight, size, power consumption, cost and the like.

[Means for solving problems]

In order to solve the above-mentioned problems, a camera motor according to the present invention has a structure in which a yoke coil is mounted on a connecting portion of two arc-shaped yoke pieces facing each other, which are obtained by dividing two concentric circles into n. 360 ° / n (n-
1) are arranged between the arc-shaped yoke pieces of the stator yoke facing each other with a space of (1) to divide the circumference into n (n−
1) n movable magnets in the shape of an arc, an n-phase yoke coil and a rotation angle of 360 ° / n divided by (n-1) n
It is characterized in that the absolute rotation stop positions of the individual pieces are configured to correspond to each other.

[Action]

In the camera motor according to the present invention, the n-phase yoke coil and the n rotation positions obtained by dividing the rotation angle of 360 ° / n by (n-1) are absolutely correspondent to the yoke coil to be energized. The rotation stop position is absolutely specified.

〔Example〕

An embodiment of a camera motor according to the present invention will be described below in detail with reference to the drawings.

The embodiment shown in FIGS. 1 to 3 is one in which the present invention is applied to a motor for zone autofocus of a video camera using a single focus lens. In this embodiment, the lens barrel 1 of the video camera is As shown in FIG. 2, a single focus lens (not shown) is inserted in a guide cylinder 3 provided with a stator base 2 so as to be screwed freely, and linearly moves in the axial direction by rotating in the axial direction. You can adjust the focus.

In the camera motor of this embodiment, n = 5 is set, and two concentric circles are divided into n (n = 5) positions at the connecting portions 11c of the two arc-shaped yoke pieces 11a and 11b facing each other. As shown in FIG. 3, five stator yokes 11 each having a yoke coil YC mounted thereon are used. As shown in FIG.
(N = 5) 4 movable arc magnets 12A,
An interval θ (θ where 12B, 12C and 12D are at 360 ° / n (n-1) with each other.
= 18 °) and 5 stator yokes 11A, 11B, 11C, 11
Arc-shaped yoke pieces 11aa, 11ab, 11ba, 11 facing each other in D and 11E
It is arranged between bb, 11ca, 11cb, 11da, 11db, 11ea, and 11eb, and is arranged to face the stator yokes 11A, 11B, 11C, 11D, and 11E.

As shown in FIG. 2, each of the stator yokes 11A, 11B, 11
C, 11D, 11E are attached and fixed to the outer peripheral portion of the stator base 2, and the movable magnets 12A, 12B,
12C and 12D are attached and fixed to a magnet base 5 provided in an outward flange shape on the outer peripheral portion of the front end of the lens barrel 1.

The camera motor in this embodiment has five rotation stop positions that are absolutely designated by selectively exciting the five stator yokes 11A, 11B, 11C, 11D and 11E.

That is, the first arc-shaped yoke piece 11aa has the N pole and the inner-arc shaped yoke piece 11ab has the S pole.
When 11A is excited, the first movable magnet 12A is stopped in a state where the stator yoke 11A faces the second movable magnet 12A so that the outer arc-shaped yoke piece 11ba becomes the N pole and the inner arc-shaped yoke piece 11bb becomes the S pole. When the stator yoke 11B is excited, it stops with the first movable magnet 12A facing the stator yoke 11B, so that the outer arc-shaped yoke piece 11ca becomes the S pole and the inner arc-shaped yoke piece 11cb becomes the N pole. When the third stator yoke 11C is excited, the second movable magnet 12B is stopped in a state of facing the stator yoke 11C, and the outer arc-shaped yoke piece 11da becomes the N pole and the inner arc-shaped yoke piece 11db becomes the S pole. When the fourth stator yoke 11D is excited, the third movable magnet 12C is stopped in a state of facing the stator yoke 11D, and the outer arc-shaped yoke piece 11ea is the S pole and the inner arc-shaped yoke piece 11eb is the N pole. To be a pole When exciting the 5 stator yoke 11E, the fourth movable magnet 12D is stopped in a state opposite to the stator yoke 11E.

Therefore, in this embodiment, the rotation direction of the camera motor is set to the positive value for the right rotation (CW) in FIG.
Of the stator yoke 11D by energizing and exciting the yoke coil YC so that the third movable magnet 12C is stopped facing the fourth stator yoke 11D, that is, the state shown in FIG. With the position at 0 °, the rotation stop positions at which the first to fifth stator yokes 11A, 11B, 11C, 11D, 11E are sequentially and selectively excited are -36 °, + 36 °,
Absolutely corresponding to −18 °, 0 °, and + 18 °, the lens barrel 1 is rotationally driven through the magnet base 5 to perform zone focus adjustment in five steps on a single focus lens (not shown).

In the embodiment having such a configuration, since the rotation stop position of the camera motor for performing the zone focus adjustment absolutely corresponds to the excitation phase of the stator yokes 11A, 11B, 11C, 11D and 11E, the auto focus adjustment is performed. It is possible to simplify the control circuit and the like necessary for performing the above, and since the lens barrel 1 is directly driven without using a reduction gear or the like, it is possible to reduce the size of the camera body and improve reliability. Further, since the stop holding torque is generated between the movable magnets 12A, 12B, 12C, 12D and the stator yokes 11A, 11B, 11C, 11D, 11E at the time of stop, the power consumption can be reduced.

〔The invention's effect〕

As is apparent from the above description of the embodiment, in the camera motor according to the present invention, n rotational positions obtained by dividing the n-phase yoke coil and the rotational angle of 360 ° / n by (n-1) are absolutely. Correspondingly, since the rotation stop position is absolutely specified for the energized yoke coil, it is possible to simplify the control circuit etc. required for autofocus adjustment, and also to require a reduction gear etc. Therefore, the camera body can be downsized, the power consumption can be reduced, and the reliability can be improved.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional front view of an essential part showing an embodiment of a camera motor according to the present invention, and FIG. 2 is a view showing a state in which the camera motor of the above embodiment is incorporated in an image pickup optical system of a video camera. FIG. 3 is a vertical sectional side view, and FIG. 3 is an enlarged perspective view showing the structure of the stator yoke in the above embodiment. 1 ... Lens barrel, 2 ... Stator base, 5 ... Magnet base, 11,11A, 11B, 11C, 11D, 11D, 11E ... Stator yoke, 11a, 11b, 11aa, 11ab, 11ba, 11bb, 11ca , 11cb, 11
da, 11db, 11ea, 11eb …… Arc yoke pieces, 12A, 12B, 12C, 1
2D: Movable magnet, YC: Yoke coil

Claims (1)

[Claims] 1. N stator yokes each having a yoke coil mounted on a connecting portion of two arc-shaped yoke pieces facing each other, which are formed by dividing two concentric circles into n, and 360 ° / n (n-1) each other. The arc-shaped (n-1) movable magnets are arranged between the arc-shaped yoke pieces of the stator yoke facing each other at a distance of n. Rotation angle of ° / n is (n-1)
A motor for a camera, characterized in that it is configured to correspond to n absolute rotation stop positions.