JP2002168308A - Motor reduction mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor speed reducing mechanism having a high degree of freedom in arrangement. SOLUTION: The motor speed reducing mechanism for transmitting the rotating force of a motor to objects to be driven comprises at least two parallel rotational center shafts, at least two gears independently and rotatably supported on one of two rotational center shafts in an axially dislocated relation, and at least one gear rotatably supported on the other, these gears engaging each other for alternately transmitting the rotation from the gears supported on one rotational center shaft to the gear supported on the other rotational center shaft.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a motor speed reduction mechanism.

[0002]

2. Description of the Related Art Conventionally, a motor reduction mechanism for reducing the rotation of a motor and transmitting the rotation to a drive target has conventionally supported a plurality of gears with different rotation center shafts. for that reason,
In general, the reduction gear train has a form extending in a direction orthogonal to the rotation center axis of the gear. However, depending on the device in which the reduction gear train is provided, it may be difficult to obtain a sufficient space for such reduction. For example, the reduction gear train provided between the motor and the driven object in the extension portion of the zoom lens barrel is arranged by connecting gears in a circumferential direction around the photographing optical axis. If an attempt is made to reduce the diameter, the space for disposing the reduction gear train will be compressed.

[0003]

The object of the present invention is therefore to provide a high degree of freedom of arrangement,
In particular, it is an object of the present invention to provide a motor speed reduction mechanism capable of reducing an installation space in a direction orthogonal to a rotation center of a gear.

[0004]

SUMMARY OF THE INVENTION According to the present invention, there is provided a motor reduction mechanism for transmitting a rotational force of a motor to an object to be driven, wherein at least two parallel central axes are provided, and one of the two central axes has an axial position. At least two gears are rotatably supported independently of each other, and at least one gear is rotatably supported on the other, and these gears are moved from the gear supported on one rotation center shaft to the other rotation center. It is characterized in that the gears are engaged so that rotation is alternately transmitted to a gear supported by a shaft. According to this motor reduction mechanism, a reduction gear ratio can be obtained by connecting gears in the direction of the rotation center axis, so that it is easy to arrange a reduction gear train corresponding to various forms of space.

In the motor speed reduction mechanism of the present invention, for example,
The two gears can be independently rotatably supported at the two rotation center shafts at different positions in the axial direction.

Each gear supported by the two parallel rotation center shafts is a double gear having a large-diameter gear portion and a small-diameter gear portion, and the small-diameter gear portion of the double gear supported by one rotation center shaft is connected to the other gear. It is preferable to alternately mesh with the large-diameter gear portion of the double gear supported by the rotation center shaft, because the rotation of the motor can be efficiently reduced.
In this case, it is preferable that the large-diameter gear portion of the double gear meshes with the previous gear in the driving force transmission sequence, and the small-diameter gear portion meshes with the next gear in the same driving force transmission sequence. Further, it is preferable that all the gears supported by the two parallel rotation center shafts are the same gear.

The above-described motor reduction mechanism includes, for example, a first lens frame and a second lens frame that respectively support first and second sub-groups that optically function at an approach position and a separation position; And a lens frame moving mechanism that causes the first and second lens frames to move toward and away from each other in the optical axis direction or move integrally with each other in the optical axis direction in accordance with the rotational drive of the forward / reverse drive motor. It is preferable to dispose the lens barrel between the forward / reverse drive motor and the lens frame moving mechanism.

According to another aspect (expression), the present invention provides a motor reduction mechanism for transmitting a rotational force of a motor to an object to be driven, wherein the first and second rotational center axes are parallel to each other; A first gear and a second gear independently rotatably supported at different positions in the axial direction; and
A third gear rotatably supported by the rotation center shaft of the first gear; the first gear meshes with the third gear; and the third gear meshes with both the first and second gears. It is characterized by having made it.

In this aspect, the second rotation center shaft further supports a fourth gear rotatable independently of the third gear, and the second gear supported on the first rotation center shaft. To
The gear can be meshed with both the fourth gear and the third gear.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [Explanation of a zoom lens system having a switching group to which the present invention can be applied] In the following embodiments, a motor speed reduction mechanism of the present invention is applied to a lens barrel described later. This lens barrel is described in Japanese Patent Application No.
It is suitable for use in the zoom lens system proposed in No. 79572. First, each aspect of a zoom lens system having a switching group proposed by the present applicant in Japanese Patent Application No. 11-79572 will be described with reference to FIGS. 1 to 9
IM indicates an image plane such as a film plane, and the image plane IM does not move. FIG. 1 shows a first mode of a zoom lens system using a switching group. This zoom lens system includes, in order from the object side, a first variable power lens group 10 having a positive power as a whole and a second variable power lens group 20 having a negative power as a whole. Numeral 10 includes, in order from the object side, a first lens unit L1 having negative power (first sub-group S1) and a second lens unit L2 having positive power (second sub-group S2). The group 20 includes a third lens group L3 having a negative power. The second sub group S2 in the first variable power lens group 10 is fixed to the first group frame 11, and the movable sub group frame 12 of the first sub group S1 has a guide groove formed in the first group frame 11. The movable member 13 can be moved by a certain distance in the optical axis direction. The first sub group S1 includes a movable sub group frame 12
A moving end on the object side abutting on the front end of the guide groove 13,
Two positions are selected from the moving end on the image plane side that contacts the rear end. The third lens group L3 is fixed to the second group frame 21.

The basic locus of zooming of the zoom lens system includes the movement of the first zoom lens group 10 (first group frame 11) and the second zoom lens group 20 (second group frame 21), and the guide groove 13. Are set as follows with the movement of the first group frame 12 (the first sub-group S1) within the camera. When zooming,
The diaphragm D moves together with the first variable power lens group 10 (first group frame 11).

A: short focal length end fw to intermediate focal length f
In the short focal length side zooming area Zw up to m, the first sub-unit S1 holds an interval (first interval, wide interval) d1 apart from the second sub-unit S2. Then, the first variable power lens group 10 (first group frame 11) and the second variable power lens group 20 (second group frame 21) both move toward the object side while changing the air gap between them.

B: At the intermediate focal length fm, the first variable power lens group 10 (first group frame 11) and the second variable power lens group 20
The (second group frame 21) moves to the image plane side from the position at the long focal length end in the short focal length zooming area Zw.
The first sub-group S1 is provided with the guide groove 13 of the first group frame 11.
In this case, an interval (second interval, narrow interval) d2 is reached, which reaches the moving end on the image plane side and approaches the second sub-group S2.

C: intermediate focal length fm to long focal length end f
In the long focal length side zooming zone Zt up to t, the first sub-group S1 is closer to the second sub-group S2 (second
D2) is held. Then, the first variable power lens group 1
0 (the first group frame 11) and the second variable power lens group 20 (the second group frame 21) set the air gap between each other based on the position after the movement to the image plane side at the intermediate focal length fm. Both move to the object side while changing.

The drawing is a simplified one, and the basic zooming locus of the first variable power lens group 10 (first group frame 11) and the second variable power lens group 20 (second group frame 21) is drawn by a straight line. But
It is not always a straight line.

In focusing, the first sub-unit S1 and the second sub-unit S2 are moved integrally in all the variable focal length regions (that is, the first variable power lens unit 10 (the first group frame 1).
1) is moved).

FIG. 2 shows a second embodiment of a zoom lens system having a switching group. The zoom lens system includes, in order from the object side, a first variable power lens group 10 having a positive power, a second variable power lens group 20 having a positive power as a whole, and a third variable power lens group 30 having a negative power. ing. The first variable power lens group 10 includes a first lens group L1 having a positive power, and the second variable power lens group 20 includes, in order from the object side, a second lens group L2 having a negative power (first sub group S1). And a third lens unit L3 (second sub-unit S2) having a positive power, and the third variable power lens unit 30 includes a fourth lens unit L4 having a negative power. The first lens unit L1 includes a first variable power lens unit frame 1
Fixed to 1. The second sub group S2 in the second variable power lens group 20 is fixed to the second group frame 21, and the movable sub group frame 22 of the first sub group S1 has a guide groove formed in the second group frame 21. It is possible to move within the optical axis 23 by a certain distance in the optical axis direction.
The first sub-group S1 selects one of two positions, a moving end on the object side where the movable sub-group frame 22 contacts the front end of the guide groove 23 and a moving end on the image plane side where it contacts the rear end. Take. The fourth lens unit L4 is fixed to the third group frame 31.

The basic zooming locus of the zoom lens system according to the second embodiment is defined by a first variable power lens group 10 (first group frame 1).
1), second variable power lens group 20 (second group frame 21) and third
With the movement of the variable power lens group 30 (third group frame 31) and the movement of the second group frame 22 (first sub group S1) in the guide groove 23, the following settings are made. At the time of zooming, the aperture D is set to the second variable power lens group 20 (the second group frame 21).
To move with.

A: short focal length end fw to intermediate focal length f
In the short focal length side zooming area Zw up to m, the first sub-unit S1 holds an interval (first interval, wide interval) d1 apart from the second sub-unit S2. Then, the first zoom lens group 10 (first group frame 11), the second zoom lens group 20 (second group frame 21), and the third zoom lens group 30 (third group frame 3)
1) both move toward the object side while changing the air gap between each other.

B: At the intermediate focal length fm, the first zoom lens group 10 (first group frame 11) and the second zoom lens group 20
The (second group frame 21) and the third variable power lens group 30 (third group frame 31) move to the image plane side from the position at the long focal length end in the short focal length side zooming area Zw. Further, the first sub-group S1 reaches the moving end on the image plane side in the guide groove 23 of the second group frame 21 and is close to the second sub-group S2 (second interval, narrow interval) d2. Take.

C: intermediate focal length fm to long focal length end f
In the long focal length side zooming zone Zt up to t, the first sub-group S1 is closer to the second sub-group S2 (second
D2) is held. Then, the first variable power lens group 1
0 (first group frame 11), second variable power lens group 20 (second group frame 21), and third variable power lens group 30 (third group frame 31)
Moves to the object side while changing the air gap between them, based on the position after the movement to the image plane side at the intermediate focal length fm.

The figure is a simplified one, in which a first zoom lens group 10 (first group frame 11), a second zoom lens group 20 (second group frame 21) and a third zoom lens group 30 ( Although the zooming basic locus of the third group frame 31) is drawn by a straight line, it is not always a straight line.

In focusing, the first sub-unit S1 and the second sub-unit S2 are moved integrally in all the variable focal length ranges (that is, the second variable power lens group 20 (the second group frame 2)).
1) is moved).

The zooming basic locus of the zoom lens system described above is discontinuous at the intermediate focal length fm, as in the first embodiment, but at the short focal length end fw, the intermediate focal length fm.
(Discontinuous point) and first lens unit L at long focal length end ft
1. By appropriately setting the positions of the first sub-group S1 (second lens group L2), the second sub-group S2 (third lens group L3) and the fourth lens group L4, an image is always correctly formed on the image plane. Such a solution exists. According to such a basic zooming locus, a compact zoom lens system can be obtained while having a high zoom ratio.

FIG. 3 shows a third embodiment of a zoom lens system having a switching group. This embodiment is the same as the second embodiment except that the most object side positive lens unit L1 in the second embodiment is replaced by the negative lens unit L1.

FIG. 4 shows a fourth embodiment of a zoom lens system having a switching group. The zoom lens system includes, in order from the object side, a first variable power lens group 10 having a positive power as a whole and a second variable power lens group 20 having a negative power as a whole.
The first variable power lens unit 10 includes, in order from the object side, a first lens unit L1 having a negative power (a first sub group S1).
1) and the second lens unit L2 having positive power (the second sub-unit S
2), and the second variable power lens group 20 includes, in order from the object side, the third lens group L3 (the third sub group S
3) and the fourth lens unit L4 having negative power (the fourth sub-unit S
4).

The second sub group S2 in the first variable power lens group 10
Is fixed to the first group frame 11, and the movable sub group frame 12 supporting the first sub group S1 is movable within the guide groove 13 formed in the first group frame 11 by a fixed distance in the optical axis direction. is there.
The first sub-group S1 selects one of two positions, a moving end on the object side where the movable sub-group frame 12 contacts the front end of the guide groove 13 and a moving end on the image plane where it contacts the rear end. Take. Similarly, the fourth sub-group S4 in the second variable power lens group 20 includes the second group frame 2
The movable sub-group frame 22 fixed to 1 and supporting the third sub-group S3 is movable within the guide groove 23 formed in the second group frame 21 by a fixed distance in the optical axis direction. Third subgroup S3
Is selected from two positions: a moving end on the object side where the movable sub-group frame 22 contacts the front end of the guide groove 23, and a moving end on the image plane side where it contacts the rear end.

The basic locus of zooming of the zoom lens system includes the movement of the first zoom lens group 10 (first group frame 11) and the second zoom lens group 20 (second group frame 21), and the guide groove 13 With the movement of the first group frame 11 (first sub-group S1) and the second group frame 21 (third sub-group S3) within and, 23 are set as follows. During zooming, the stop D moves together with the first variable power lens group 10 (first group frame 11).

A: short focal length end fw to intermediate focal length f
In the short focal length side zooming area Zw up to m, the first sub-group S1 holds an interval (first interval, wide interval) d1 apart from the second sub-group S2, and the third sub-group S3 has the Intervals separated from 4 subgroups S4 (first interval, wide interval)
Take d3. Then, the first variable power lens group 10 (first group frame 11) and the second variable power lens group 20 (second group frame 21) both move toward the object side while changing the air gap between them.

B: At the intermediate focal length fm, the first zoom lens group 10 (first group frame 11) and the second zoom lens group 20
The (second group frame 21) moves to the image plane side from the position at the long focal length end in the short focal length zooming area Zw.
The first sub-group S1 is provided with the guide groove 13 of the first group frame 11.
, Reaches the moving end on the image plane side, takes an interval (second interval, narrow interval) d2 close to the second sub-unit S2, and the third sub-unit S3 approaches the fourth sub-unit S4. Interval (second
, D4).

C: intermediate focal length fm to long focal length end f
In the long focal length side zooming zone Zt up to t, the first sub-group S1 holds an interval (narrow interval) d2 close to the second sub-group S2, and the third sub-group S3 holds the fourth sub-group S4. Is maintained at an interval (narrow interval) d4 that is close to. The first variable power lens group 10 (first group frame 11) and the second variable power lens group 20 (second group frame 21) are based on the position after the movement to the image plane side at the intermediate focal length fm. Then, both are moved to the object side while changing the air gap between them.

In the drawing, for the sake of convenience, the first variable power lens group 10
(First group frame 11) and second variable power lens group 20 (second group frame 2)
Although the zooming basic trajectory of 1) is drawn by a straight line, it is not always a straight line.

In focusing, the first sub-unit S1 and the second sub-unit S2 are moved integrally (ie, in the first variable power lens unit 10 (the first unit frame 1) in all variable focal length regions.
1) is moved).

The basic zooming trajectory of the above-described zoom lens system has an intermediate focal length f, as in the first to third embodiments.
m, the first at the short focal length end fw, the intermediate focal length fm (discontinuous point), and the first at the long focal length end ft.
Sub group S1 (first lens group L1), second sub group S2 (second lens group L2), third sub group S3 (third lens group L)
By appropriately setting the position of 3) and the fourth sub-group S4 (fourth lens group L4), there is a solution that always forms a correct image on the image plane. According to such a basic zooming locus, a compact zoom lens system can be obtained while having a high zoom ratio.

FIG. 5 shows a fifth embodiment of the zoom lens system having a switching group. The zoom lens system includes, in order from the object side, a first variable power lens group 10 having a positive power as a whole and a second variable power lens group 20 having a negative power as a whole.
The first variable power lens unit 10 includes, in order from the object side, a first lens unit L1 having a negative power (a first sub group S1).
1) and the second lens unit L2 having positive power (the second sub-unit S
2), and the second variable power lens group 20 includes, in order from the object side, the third lens group L3 (the third sub group S
3) and the fourth lens unit L4 having negative power (the fourth sub-unit S
4).

The second sub group S2 in the first variable power lens group 10
Is fixed to the first group frame 11, and the movable sub group frame 12 supporting the first sub group S1 is movable within the guide groove 13 formed in the first group frame 11 by a fixed distance in the optical axis direction. is there.
The first sub-group S1 selects one of two positions, a moving end on the object side where the movable sub-group frame 12 contacts the front end of the guide groove 13 and a moving end on the image plane where it contacts the rear end. Take. Similarly, the fourth sub-group S4 in the second variable power lens group 20 includes the second group frame 2
The movable sub-group frame 22 fixed to 1 and supporting the third sub-group S3 is movable within the guide groove 23 formed in the second group frame 21 by a fixed distance in the optical axis direction. Third subgroup S3
Is selected from two positions: a moving end on the object side where the movable sub-group frame 22 contacts the front end of the guide groove 23, and a moving end on the image plane side where it contacts the rear end.

The basic locus of zooming of the zoom lens system is based on the movement between the first variable power lens group 10 (first group frame 11) and the second variable power lens group 20 (second group frame 21), and the guide groove 13 With the movement of the first group frame 11 (first sub-group S1) and the second group frame 21 (third sub-group S3) within and, 23 are set as follows. During zooming, the stop D moves together with the first variable power lens group 10 (first group frame 11).

A: In the short focal length side zooming zone Zw from the short focal length end fw to the first intermediate focal length fm1,
The first sub-group S1 holds an interval (first interval, wide interval) d1 that is separated from the second sub-group S2, and the third sub-group S3
Is an interval apart from the fourth subgroup S4 (first interval,
(Wide interval) d3 is taken. Then, the first variable power lens group 10
(First group frame 11) and second variable power lens group 20 (second group frame 2)
1) both move toward the object side while changing the air gap between each other.

B: At the intermediate focal length fm1, the first zoom lens group 10 (first group frame 11) and the second zoom lens group 20 (second group frame 21) are in the short focal length side zooming zone Z.
It moves to the image plane side from the position at the end of the long focal length in w. Further, the first sub-group S1 reaches the moving end on the image plane side in the guide groove 13 of the first group frame 11 and is close to the second sub-group S2 (second interval, narrow interval) d2. Take.

C: In the intermediate zooming zone Zm from the first intermediate focal length fm1 to the second intermediate focal length fm2,
The first sub-group S1 holds an interval (second interval, narrow interval) d2 close to the second sub-group S2, and the third sub-group S3
Is an interval apart from the fourth subgroup S4 (first interval,
(Wide interval) d3 is held. Then, the first variable power lens group 1
0 (the first group frame 11) and the second variable power lens group 20 (the second group frame 21) are based on the position after the movement to the image plane side at the first intermediate focal length fm1. Both move to the object side while changing the air gap.

D: At the second intermediate focal length fm2,
The first variable power lens group 10 (first group frame 11) and the second variable power lens group 20 (second group frame 21) have an intermediate zooming area Zm.
It moves to the image plane side from the position at the long focal point side end portion. Further, the third sub-group S3 reaches the moving end on the image plane side in the guide groove 23 of the second group frame 21 and is close to the fourth sub-group S4 (second interval, narrow interval) d4. Take.

E: In the long focal length side zooming zone Zt from the second intermediate focal length fm2 to the long focal length end ft,
The first sub-group S1 holds an interval (narrow interval) d2 close to the second sub-group S2, and the third sub-group S3 sets an interval (narrow interval) d4 close to the fourth sub-group S4. Hold. Then, the first zoom lens group 10 (first group frame 11) and the second zoom lens group 20 (second group frame 21) move to the image plane side at the second intermediate focal length fm2. Based on the position, they move toward the object side while changing the air gap between them.

The drawing is a simple one, in which the basic zooming locus of the first zoom lens group 10 (first group frame 11) and the second zoom lens group 20 (second group frame 21) are drawn by straight lines. But
It is not always a straight line.

In focusing, the first sub-unit S1 and the second sub-unit S2 are moved integrally in all variable focal length ranges (that is, the first variable power lens unit 10 (the first group frame 1).
1) is moved).

The basic locus of zooming of the zoom lens system described above has an intermediate focal length f, as in the first to fourth embodiments.
m, but at the short focal length end fw, the first,
The first sub-group S1 (the first lens group L) at the second intermediate focal lengths fm1, fm2 (discontinuous points) and the long focal length end ft
1), a second sub-group S2 (second lens group L2), a third sub-group S3 (third lens group L3), and a fourth sub-group S4 (fourth
By appropriately determining the position of the lens unit L4), there is a solution that always forms a correct image on the image plane. According to such a basic zooming locus, a compact zoom lens system can be obtained while having a high zoom ratio.

FIG. 6 shows a sixth embodiment of the zoom lens system having a switching group. The zoom lens system includes, in order from the object side, a first variable power lens group 10 having a positive power as a whole and a second variable power lens group 20 having a negative power as a whole.
The first variable power lens unit 10 includes, in order from the object side, a first lens unit L1 having a negative power (a first sub group S1).
1) and the second lens unit L2 having positive power (the second sub-unit S
2), and the second variable power lens group 20 includes, in order from the object side, the third lens group L3 (the third sub group S
3) and the fourth lens unit L4 having negative power (the fourth sub-unit S
4).

The second sub group S2 in the first variable power lens group 10
Is fixed to the first group frame 11, and the movable sub group frame 12 supporting the first sub group S1 is movable within the guide groove 13 formed in the first group frame 11 by a fixed distance in the optical axis direction. is there.
The first sub-group S1 selects one of two positions, a moving end on the object side where the movable sub-group frame 12 contacts the front end of the guide groove 13 and a moving end on the image plane where it contacts the rear end. Take. Similarly, the fourth sub-group S4 in the second variable power lens group 20 includes the second group frame 2
The movable sub-group frame 22 fixed to 1 and supporting the third sub-group S3 is movable within the guide groove 23 formed in the second group frame 21 by a fixed distance in the optical axis direction. Third subgroup S3
Is selected from two positions: a moving end on the object side where the movable sub-group frame 22 contacts the front end of the guide groove 23, and a moving end on the image plane side where it contacts the rear end.

The basic locus of zooming of the zoom lens system includes the movement of the first variable power lens group 10 (first group frame 11) and the second variable power lens group 20 (second group frame 21), and the guide groove 13 With the movement of the first group frame 11 (first sub-group S1) and the second group frame 21 (third sub-group S3) within and, 23 are set as follows. During zooming, the stop D moves together with the first variable power lens group 10 (first group frame 11).

A: In the short focal length side zooming region Zw from the short focal length end fw to the first intermediate focal length fm1,
The first sub-group S1 holds an interval (first interval, wide interval) d1 that is separated from the second sub-group S2, and the third sub-group S3
Is an interval apart from the fourth subgroup S4 (first interval,
(Wide interval) d3 is taken. Then, the first variable power lens group 10
(First group frame 11) and second variable power lens group 20 (second group frame 2)
1) both move toward the object side while changing the air gap between each other.

B: At the intermediate focal length fm1, the first zoom lens group 10 (first group frame 11) and the second zoom lens group 20 (second group frame 21) are in the short focal length side zooming zone Z.
It moves to the image plane side from the position at the end of the long focal length in w. Further, the third sub-group S3 reaches the moving end on the image plane side in the guide groove 23 of the second group frame 21 and is close to the fourth sub-group S4 (second interval, narrow interval) d4. Take.

C: In the intermediate zooming zone Zm from the first intermediate focal length fm1 to the second intermediate focal length fm2,
The first sub-group S1 holds an interval (first interval, wide interval) d1 separated from the second sub-group S2, and the third sub-group S3
Is the distance close to the fourth subgroup S4 (the second distance,
(Narrow interval) d4 is maintained. Then, the first variable power lens group 1
0 (the first group frame 11) and the second variable power lens group 20 (the second group frame 21) are based on the position after the movement to the image plane side at the first intermediate focal length fm1. Both move to the object side while changing the air gap.

D: At the second intermediate focal length fm2,
The first variable power lens group 10 (first group frame 11) and the second variable power lens group 20 (second group frame 21) have an intermediate zooming area Zm.
It moves to the image plane side from the position at the long focal point side end portion. Further, the first sub-group S1 reaches the moving end on the image plane side in the guide groove 13 of the first group frame 11 and is close to the second sub-group S2 (second interval, narrow interval) d2. Take.

E: In the long focal length side zooming zone Zt from the second intermediate focal length fm2 to the long focal length end ft,
The first sub-group S1 holds an interval (narrow interval) d2 close to the second sub-group S2, and the third sub-group S3 sets an interval (narrow interval) d4 close to the fourth sub-group S4. Hold. Then, the first zoom lens group 10 (first group frame 11) and the second zoom lens group 20 (second group frame 21) move to the image plane side at the second intermediate focal length fm2. Based on the position, they move toward the object side while changing the air gap between them.

The drawing is a simplified one, and the basic zooming locus of the first variable power lens group 10 (first group frame 11) and the second variable power lens group 20 (second group frame 21) is drawn by a straight line. But
It is not always a straight line.

In focusing, the first sub-unit S1 and the second sub-unit S2 are moved integrally in all variable focal length ranges (that is, the first variable power lens unit 10 (the first group frame 1)).
1) is moved).

The basic zooming locus of the zoom lens system described above is the intermediate focal length f, as in the first to fifth embodiments.
m, but at the short focal length end fw, the first,
The first sub-group S1 (the first lens group L) at the second intermediate focal lengths fm1, fm2 (discontinuous points) and the long focal length end ft
1), a second sub-group S2 (second lens group L2), a third sub-group S3 (third lens group L3), and a fourth sub-group S4 (fourth
By appropriately determining the position of the lens unit L4), there is a solution that always forms a correct image on the image plane. According to such a basic zooming locus, a compact zoom lens system can be obtained while having a high zoom ratio.

FIG. 7 shows a seventh embodiment of the zoom lens system having a switching group. The zoom lens system includes, in order from the object side, a first variable power lens group 10 having a positive power as a whole and a second variable power lens group 20 having a negative power. The first variable power lens unit 10 includes, in order from the object side, a first lens L1 having a positive power (first sub group S1), a second lens group L2 having a negative power (second sub group S2), and a positive lens. A third lens unit L3 (third sub-unit S3) having a power,
The second variable power lens unit 20 is a fourth lens unit L4 having a negative power.
Consists of First sub group S of the first variable power lens group 10
The first and third sub-groups S3 are fixed to the first group frame 11, and the movable sub-group frame 12 supporting the second sub-group S2 has an optical axis within a guide groove 13 formed in the first group frame 11. It can move a certain distance in the direction. The second sub-group S2 selects one of two positions, a moving end on the object side where the movable sub-group frame 12 contacts the front end of the guide groove 13 and a moving end on the image plane where the movable sub-group frame 12 contacts the rear end. Take. The fourth lens unit L4 is fixed to the second group frame 21.

The basic locus of zooming of the zoom lens system includes the movement of the first zoom lens group 10 (first group frame 11) and the second zoom lens group 20 (second group frame 21), and the guide groove 13 Are set as follows with the movement of the first group frame 11 (the second sub-group S2) within the camera. When zooming,
The diaphragm D moves together with the first variable power lens group 10 (first group frame 11).

A: short focal length end fw to intermediate focal length f
In the short focal length side zooming area Zw up to m, the second sub-unit S2 has a narrow distance close to the first sub-unit S1,
The wide distance apart from the sub-group S3 is maintained. Then, the first variable power lens group 10 (first group frame 11) and the second variable power lens group 20 (second group frame 21) both move toward the object side while changing the air gap between them.

B: At the intermediate focal length fm, the first zoom lens group 10 (first group frame 11) and the second zoom lens group 20
The (second group frame 21) moves to the image plane side from the position at the long focal length end in the short focal length zooming area Zw.
Further, the second sub-group S2 includes the guide groove 13 of the first group frame 11.
In this case, the moving end on the image plane side is reached, and a wide interval is set apart from the first sub-unit S1, and a narrow interval is set close to the third sub-unit S3.

C: intermediate focal length fm to long focal length end f
In the long focal length side zooming zone Zt up to t, the second sub-group S2 keeps a wide interval apart from the first sub-group S1, and a narrow interval close to the third sub-group S3. The first variable power lens group 10 (first group frame 11) and the second variable power lens group 20 (second group frame 21) are based on the position after the movement to the image plane side at the intermediate focal length fm. Then, both are moved to the object side while changing the air gap between them.

The drawing is a simplified one, and the basic zooming locus of the first variable power lens group 10 (first group frame 11) and the second variable power lens group 20 (second group frame 21) is drawn by a straight line. But
It is not always a straight line.

In focusing, the first sub-group S1 to the third sub-group S3 are moved integrally (ie, the first variable power lens group 10 (the first group frame 11) is moved in all variable focal length regions). Do).

The basic zooming locus of the zoom lens system described above is the intermediate focal length f, as in the first to sixth embodiments.
m, the first at the short focal length end fw, the intermediate focal length fm (discontinuous point), and the first at the long focal length end ft.
Sub group S1 (first lens group L1), second sub group S2 (second lens group L2), third sub group S3 (third lens group L)
By appropriately setting the position of the third lens unit L4 and the fourth lens unit L4, there is a solution that always forms an image on the image plane correctly.
According to such a basic zooming locus, a compact zoom lens system can be obtained while having a high zoom ratio.

As described above, the zoom lens system having the above-described switching group is practically used as a photographing lens system of a camera in which the photographing lens system and the finder optical system have different optical axes. The stop position during zooming of each lens group during shooting is preferably determined stepwise on the basic zooming locus, that is, a plurality of focal length steps. FIGS. 8 and 9 show an example in which the stop position of each lens group during zooming is stepwise. In this example, the first embodiment of FIG. 1 is used as an example, and the same components as those of FIG. 1 are denoted by the same reference numerals. The basic zooming locus is indicated by a broken line, and the stop positions of the first group frame 11 and the second group frame 21 at the time of zooming during shooting are indicated by black circles on the zooming locus indicated by the broken line. FIG. 9 is a drawing in which the moving trajectory connecting the black circles in FIG. 8 with smooth curves is drawn by a solid line. In an actual mechanical configuration, the first group frame 11 and the second group frame 21 are moved in this manner. be able to.

In each of the embodiments described above, each lens group is illustrated as a single lens for convenience, but these may be composed of a plurality of lenses.

[Explanation of Overall Structure of Zoom Lens Barrel Having Switching Group] In each of the above embodiments, FIGS.
The first variable power lens group 10 of the mode of FIG. 4, the second variable power lens group 20 of the mode of FIG. 2, the second variable lens group 20 of the mode of FIG. 3, the first variable lens group 10 of the mode of FIG. The first variable power lens group 10 in the mode of FIG. 5, the first variable power lens group 10 in the mode of FIG. 6,
And the first variable power lens group 10 (first lens L
1 and the third lens L3) are switching groups, and function as focus lens groups in the entire focal length range.

The following description relates to a lens barrel adaptable to the above-mentioned switching group. Hereinafter, the first variable-magnification lens group (switching group) 10 and the second variable-magnification in the embodiments shown in FIGS. 1, 8 and 9 will be described. An embodiment applied to a zoom lens barrel having a lens group 20 will be described. In the zoom lens barrel (system) of the embodiment shown in FIG. 10 and subsequent figures, one of the first sub-groups S1 and S2 constituting the switching group 10 is fixed to the first group frame 11, FIGS.
Is different from the first zoom lens system, the first sub-groups S1 and S2
Are movable in the optical axis direction with respect to the switching group frame. In this mode, the movement trajectory given to the switching group frame during the zooming operation and the first sub-group S1 and the second sub-group S2 in the switching group frame
, The combined trajectory with the moving trajectory given in FIG. At the time of focusing, the first sub-group S1 and the second sub-group S2 are integrally moved in the optical axis direction within the switching group frame. The actual operation is based on the focal length information set by the operator and the detected subject distance information, before the shutter release starts, the movement of the switching group frame and the first sub-frame in the switching group frame. The first sub-group S1 and the second sub-group S2 may be located at predetermined positions in the optical axis direction by the movement of the group S1 and the second sub-group S2.

As shown in FIG. 10, the fixed cylinder 42 fixed to the camera body 41 has a female helicoid 43 formed on the inner peripheral surface thereof. A male helicoid 45 formed around the rear end of the cam ring 44 is screwed into the female helicoid 43. On the other hand, a pinion 47 driven by a zooming motor 46 is positioned outside the fixed cylinder 42, and a male helicoid 45 is attached to the pinion 47.
And a gear (not shown) formed on the outer periphery of the cam ring 44 by being inclined in the same direction as the lead of the male helicoid 45 is engaged. Therefore, when the cam ring 44 is given forward and reverse rotational motions via the zooming motor 46, the cam ring 44 advances and retreats in the optical axis direction according to the female helicoid 43 and the male helicoid 45. The rotational position of the cam ring 44 by the zooming motor 46 is detected by a focal length detecting means 46C composed of, for example, a code plate and a brush.

The cam ring 44 supports a rectilinear guide ring 48 which can rotate relative to the cam ring 44 and move together in the optical axis direction (cannot move relative to the optical axis direction).
The rectilinear guide ring 48 is supported by the camera body 41 so as to permit only rectilinear movement in the optical axis direction. Inside the cam ring 44, in order from the front, the first variable power lens group 10
The switching group frame 50 having the (first sub-group S1 and the second sub-group S2) and the rear group lens frame 49 to which the second variable power lens group 20 is fixed are located. The group lens frame 49 is guided linearly in the optical axis direction by a linear guide ring 48.

On the inner peripheral surface of the cam ring 44, there are formed bottomed cam grooves 44f and 44r for the switching group frame 50 and the rear group lens frame 49. FIG. 11 shows the bottomed cam grooves 44f and 44r.
3 shows the developed shape of the. Three sets of the bottomed cam grooves 44f and 44r are formed at equal angular intervals in the circumferential direction, and the switching group frame 50 and the rear group lens frame 49 have follower pins 50p fitted into these bottomed cam grooves 44f and 44r. And 49p
Are formed so as to protrude in the radial direction.

The bottomed cam grooves 44f and 44r are respectively provided with the follower pins 50p and 49p introduction positions 44f-a and 44p, respectively.
ra, zoom lens system storage positions 44fr, 44r
-R, wide end positions 44f-w, 44r-w, and tele end positions 44ft, 44rt. From the introduction positions 44f-a, 44r-a to the storage positions 44fr, 44
Rotation angle to rr is θ1, storage positions 44fr, 44r
The rotation angle from −r to the wide end positions 44fw and 44r−w is θ2, and the rotation angle from the wide end positions 44fw and 44r−w to the tele end positions 44ft and 44rt is θ3. A rotation angle θ4 exceeding the tele end positions 44ft and 44rt is a rotation angle for assembly. The cam groove 44r for the rear lens group frame 49 has an intermediate discontinuous position fm corresponding to the basic zooming locus of the second variable power lens group 20 in the modes shown in FIGS.

On the other hand, the cam groove 44f for the first variable power lens group 10 changes its shape smoothly from the wide end position 44fw to the telephoto end position 44ft, and apparently has a different shape. There is no discontinuous position. This is because, in the present embodiment, the switching group frame 50 is arranged so that the position of the sub-group S2 is not discontinuous in the short focal length zooming zone Zw and the long focal length zooming zone Zt sandwiching the intermediate focal length fm in FIG. And that the sub-group S2 is moved. A connection line CC schematically shown in FIG. 1 includes a short focal length side zooming area Zw and a long focal length side zooming area Zt sandwiching the intermediate focal length fm.
The cam groove 44f
Corresponds to the basic zooming locus connected by the connection line CC. Follower pin 50p is connected to this connection line C
While moving in the section corresponding to C, the sub-group S1 moves from the front moving end to the rear moving end. The section of the cam groove 44f corresponding to the connection line CC is controlled not to be used for photographing (not to stop the cam ring 44) as an actual zooming area. Of course, like the cam groove 44r,
It is also possible to provide discontinuous parts.

When the pinion 47 is rotationally driven forward and reverse via the zooming motor 46, the zoom lens barrel having the above-described structure moves forward and backward in the optical axis direction while rotating the cam ring 44.
The switching group frame 50 (first variable-magnification lens group 10) and the rear group lens frame 49 (second variable-magnification lens group 20), which are guided straight in the optical axis direction in the cam ring 44, have a cam groove 44f with a bottom. It moves straight in the optical axis direction along a predetermined locus according to 44r.

A zoom lens barrel that gives the above-described operation to the switching group frame 50 and the rear group lens frame 49 is well known.
The above is an example. The feature of the present embodiment lies in the support structure of the first sub-group S1 and the second sub-group S2 with respect to the switching group frame 50 and the driving structure thereof. Switching group frame 50
The specific structure in FIG.

In the switching group frame 50, a front shutter holding ring 51, a rear shutter holding ring 52, a front sub group frame 53, a rear sub group frame 54, a drive ring 55, and a gear press ring 56 are located. The front shutter holding ring 51, the rear shutter holding ring 52, and the gear holding ring 56 constitute a part of the switching group frame 50. The first sub-group S1 is fixed to a front sub-group frame (first lens group frame, holding ring) 53, and the second sub-group S2 is a rear sub-group frame (second lens group frame, holding ring) 54.
Fixed to. Front sub-group frame 53, rear sub-group frame 5
4 and a drive ring 55 are movable members for performing a contact / separation switching operation and a focusing operation of the front sub-group frame 53 and the rear sub-group frame 54 (the first sub-group S1 and the second sub-group S2). It is fitted in the center opening 51p of the holding frame 51. The drive ring 55 is provided with a thrust surface 52a of the rear shutter holding ring 52 (see FIGS. 13, 15, and 1).
The rear end position is regulated by 6), and is rotatably supported between the front and rear shutter holding rings 51, 52. The drive ring 55 is a drive member that performs a contact / separation switching operation and a focusing operation between the first sub-unit S1 and the second sub-unit S2 by the forward / reverse rotation. A gear holding ring 56 is fixed in front of the front shutter holding ring 51, and the rear shutter holding ring 52 includes a lens shutter 57 and a diaphragm mechanism 58.
(FIGS. 12, 15, and 16).

The front sub-group frame 53 has a cylindrical shape, and is provided with linear guide ribs 53a at two locations outside in the diameter direction. A guide hole 5 formed in the straight guide rib 53a
3b, a rectilinear guide rod 59 is loosely inserted (loosely fitted), the rear end of the rectilinear guide rod 59 is fixed to a fixing hole 56q at the bottom of the gear holding ring 56, and the front end is a fixing bracket. It is fixed to the front end surface of the gear holding ring 56 via a fixing screw 61 and a fixing screw 61. A compression coil spring 62, which is located between the fixed bracket 60 and the linear guide rib 53a and urges the front sub-group frame 53 toward the rear sub-group frame 54, is fitted on the outer periphery of the linear guide rod 59. The gear holding ring 56 is formed with a U-shaped recess 56r for accommodating the linear guide rod 59 and the compression coil spring 62 (see FIGS. 25 to 27). The storage recess 56r communicates with the center opening 51p of the front shutter holding ring 51. The rotation direction of the front sub-group frame 53 is 1
At two positions inverted by 80 °, the straight guide ribs 53a
Can be assembled with the straight guide rod 59 of the front shutter holding ring 51.

In the front sub-group frame 53, four sets of contact / separation lead surfaces (contact / separation cam surfaces) 53c are formed at equal angular intervals in the circumferential direction in the form of an end surface cam having an open rear end surface.
An annular light-shielding reinforcing rib 53d is formed so as to cover the outside of the open end of the contact / separation lead surface 53c. FIG.
Is an enlarged development view of the contact / separation lead surface 53c. The contact / separation lead surface 53c is formed into a straight line inclined at an inclination angle α with respect to the circumferential direction, and the contact / separation lead surface 53c is deepened into a shallow V-shape at both ends. Follower stabilizing recesses 53e and 53f are formed. The follower stabilizing recess 53e regulates the wide-side separation position of the front sub-group frame 53 and the rear sub-group frame 54 (the first sub-group S1 and the second sub-group S2), and the follower stabilizing recess 53f adjusts the tele-side approach position. regulate.

On the outer peripheral surface of the rear sub-group frame 54, four sets of follower projections 54a are formed corresponding to the four sets of contact / separation lead surfaces 53c of the front sub-group frame 53. The follower protrusion 54a is the most proximate lead surface 5 of the inclined surface 54b corresponding to the proximate lead surface 53c of the front sub-group frame 53.
It is provided at the tip of the portion located on the 3c side. The tip of the follower projection 54a has a substantially semicircular shape that is symmetrical to the left and right, and the follower stabilizing recesses 53e and 53f correspond to the tip of the follower projection 54a. The follower protrusion 54a and the inclined surface 54b
An annular light-shielding reinforcing rib 54c is formed on the inner side of the inner wall. The contact / separation lead surface 53c formed on the front sub-group frame 53 and the follower projection 54 formed on the rear sub-group frame 54
a constitutes a contact / separation cam mechanism for bringing the lens group frames 53 and 54 into and out of contact with each other. Four sets of contact / separation lead surfaces 53c of the front sub-group frame 53 and four follower protrusions 54a of the rear sub-group frame 54
Are formed at equal angular intervals as described above.
It can be engaged at different relative rotational positions every 0 °. The number (N, 4 in the embodiment) of the contact / separation lead surface 53c and the follower protrusion 54a is determined by the linear guide rib 53 of the front sub-group frame 53.
As for a and the number (M, 2 in the embodiment) of the straight guide rods 59 of the front shutter holding ring 51, M is a multiple of N and N is a divisor of M. According to this relationship, selective assemblability in the rotation direction is obtained, and for example, an assembling position at which the most preferable optical performance is obtained can be selected.

The rear sub-group frame 54 has, on its outer peripheral surface, the same circumferential position as the two follower protrusions 54a that are diametrically opposed among the four follower protrusions 54a.
A rectilinear guide protrusion 54d is formed so as to protrude behind the follower protrusion 54a in the optical axis direction. Further, a straight guide protrusion 54d is provided on the outer peripheral surface of the rear sub-group frame 54.
Three driven projections 54e are formed so as to be further rearward in the optical axis direction at equal angular intervals. This driven projection 5
4e is a pair of parallel circumferentially separated driven surfaces N1 and N2 that are circumferentially separated from each other, and connects the driven surfaces N1 and N2, and has a smooth cylindrical surface having its rotation axis in a direction perpendicular to the optical axis ( N3), and has a symmetrical shape with respect to a line (center line) passing through the centers of the driven surfaces N1 and N2 in the circumferential direction and parallel to the optical axis.

The rotation range of the rear sub-group frame 54 with respect to the non-rotating front shutter holding ring 51 is provided on the inner peripheral surface of the front shutter holding ring 51 so as to correspond to each of the rectilinear guide protrusions 54 d of the rear sub-group frame 54. A pair of rotation regulating surfaces 5 for defining
1a and 51b are formed (see FIG. 24). That is, the rotation restricting surfaces 51a and 51b are
When the rotary member 4 rotates in the forward and reverse directions, it engages with the circumferential separation stopper surfaces M1 and M2 of the linear guide protrusion 54d to regulate the rotation end. The rotation restricting surface 51a is
A wide-side straight guide groove 51d is formed between the stopper surface M2 and the guide surface 51c engaged with the stopper surface M2, and the rotation restricting surface 51b
Constitutes a tele-side rectilinear guide groove 51f between the stopper surface M1 of the rectilinear guide projection 54d and the engaging guide surface 51e. That is, the circumferential width of the wide-side straight guide groove 51d and the tele-side straight guide groove 51f corresponds to the width of the straight guide protrusion 54d in the same direction, and the guide protrusion 54d is engaged with substantially no gap. . The clearance between the wide-side or tele-side straight guide grooves 51d and 51f and the straight guide protrusion 54d is set smaller (stricter) than the clearance between the guide hole 53b of the front sub-group frame 53 and the straight guide rod 59. The straight guide projection 54 of the rear sub-group frame 54
d is located at a diametrically opposed position, and the rectilinear guide grooves 51d and 51f of the front shutter holding ring 51 select the rotational position of the two rectilinear guide protrusions 54d (that is, determine the rotational position of the rear sub-group frame 54. A pair is provided so that they can be fitted (inverted 180 °).

The drive ring 55 has, on its front end face, three sets of control recesses 55a corresponding to the three driven projections 54e of the rear sub-group frame 54 (see FIG. 22). The control concave portion 55a has a symmetrical shape with respect to a center line c in a direction parallel to the optical axis, and has a pair of rotation imparting surfaces 55 that engage with the circumferentially separated driven surfaces N1 and N2 of the driven projection 54e.
b and 55c, and telephoto and wide-side focus lead surfaces (focus cam surfaces) 55d and 55e that come into contact with the cylindrical surface N3 of the driven projection 54e. The tele-side focus lead surface 55d and the wide-side focus lead surface 55e are formed between the rotation imparting surfaces 55b and 55c in the form of an end surface cam having an open front end surface. , The absolute values are the same. The outer peripheral side front of the control concave portion 55a of the drive ring 55 is covered with an annular light shielding reinforcing rib 55f. This drive ring 55
The focus lead surfaces 55d and 55e and the driven protrusion 54e formed on the rear sub-group frame 54 constitute a focus cam mechanism. Three driven projections 54e of the rear sub-group frame 54
The three control concave portions 55a of the drive ring 55 are provided at equal angular intervals as described above, and can be engaged at different relative rotation positions every 120 °.

The cylindrical surface N3 of the driven projection 54e is
Focus lead surfaces 55d, 5 having tilt directions opposite to each other.
Due to the contact with 5e, each focus lead surface 55d,
It is formed in a cylindrical shape in order to avoid interference with 55e and perform reliable power transmission. Conversely, the circumferentially separated driven surfaces N1 and N2 of the driven protrusion 54e are parallel planes, but the rotation transmission from the rotation imparting surfaces 55b and 55c can be performed without using such a parallel plane. For example, this driven surface N
Instead of 1 and N2, the contact portion with the rotation imparting surfaces 55b and 55c may be a cylindrical surface similar to the cylindrical surface N3 (continuous with the cylindrical surface N3). That is, the entire outer peripheral surface of the driven projection (at least the focus lead surface 5
5d, 55e, and the rotation imparting surfaces 55b,
5c) may be formed in a cylindrical shape.

The above-described compression coil spring 62 for pressing and urging the front sub-group frame 53 backward is provided with the contact / separation lead surface 53c of the front sub-group frame 53 and the follower projection 54 of the rear sub-group frame 54.
a, the driven protrusion 54e of the rear sub-group frame 54 (the cylindrical surface N
3) The focus lead surfaces 55d and 55e on the tele side or the wide side of the drive ring 55 are always in contact with each other. As described above, the drive ring 55 has its rear end surface abutting on the thrust surface 52a of the rear shutter holding ring 52, and the front sub-group frame 53,
The contact relationship between the rear sub-group frame 54, the drive ring 55, and the rear shutter holding ring 52 (thrust surface 52a) is maintained. In these contact states, the tip of the rear sub-group frame 54 enters the inner periphery of the front sub-group frame 53 and the drive ring 55 is positioned on the outer periphery of the rear sub-group frame 54, as is apparent from FIGS. are doing.

FIGS. 21A to 21H show the front sub-group frame 5 formed by the rotation applying surfaces 55b and 55c of the drive ring 55.
3 and the rear subgroup frame 54 (the first subgroup S1 and the second subgroup S
2) shows the switching operation between the tele side approach state and the wide side separation state of 2). In FIG. 21, the solid arrow indicates the rotation direction of the drive ring 55. The state (A) shown in the upper left end of FIG. 21 is the rotation applying surface 55b of the drive ring 55.
Are in contact with the driven protrusion 54e, and the rectilinear guide protrusion 54d of the rear sub-group frame 54 is separated from the wide rectilinear guide groove 51d. In this state, the drive ring 55
Moves to the right in the figure (rotates clockwise), the rotation applying surface 55b is moved by the driven surface N1 of the driven protrusion 54e.
Is pressed to rotate the rear sub-group frame 54 in the same direction, and then the straight guide projection 54d is brought into contact with the rotation regulating surface 51b.
That is, the state is shifted from (A) to (C) in FIG.
During this time, the front sub-group frame 53 (first sub-group S1) includes the contact / separation lead surface 53c and the follower projections 54 of the rear sub-group frame 54.
a, the rear sub-group frame 54 (the second sub-group S2) approaches (FIG. 21B), and finally the follower protrusion 54
a is engaged with the follower stabilizing recess 53f to be in a stable state (FIG. 21C). Since four follower projections 54a and four follower stabilizing recesses 53f are formed at equal angular intervals in the circumferential direction, all of them are engaged with each other.
The eccentricity of the front sub-group frame 53 and the rear sub-group frame 54 is eliminated. As described above, the switching from the wide-side separation state to the tele-side approach state is completed, and the first sub-group S1 is in a state of approaching the second sub-group S2 (approaching movement end). No further rotation of the drive ring 55 in the same direction is possible.

When the switching to the tele side approaching state is completed, the drive ring 55 rotates in the reverse direction. Then, the driven projection 54
e (rear sub-group frame 54) is the tele-side focus lead surface 5
In order to move backward according to 5d, the straight guide projection 54d
Can enter only the tele-side straight guide groove 51f and can only move straight in the optical axis direction. By the integral movement of the rear sub-group frame 54 and the front sub-group frame 53 at the approach movement end by the tele-side focus lead surface 55, focusing on the tele side from the intermediate focal length to the long focal length end is performed (FIG. 21).
(D)).

Then, the rotation applying surface 55 c is
When the drive ring 55 rotates until it abuts on the driven surface N2 of e, the rectilinear guide protrusion 54d of the rear sub-group frame 54 comes off from the tele-side rectilinear guide groove 51f (FIG. 21E).

In this state, when the driving ring 55 reverses the rotation direction and moves to the left in the figure (rotates counterclockwise), the rotation applying surface 55c is moved by the driven surface N2 of the driven projection 54e.
Is pressed to rotate the rear sub-group frame 54 in the same direction, and the stopper surface M1 of the straight guide protrusion 54d is eventually turned to the rotation restricting surface 51.
a. That is, the state changes from (E) to (G) in FIG. During this time, the front sub-group frame 53 includes the contact / separation lead surface 53c and the follower projections 54a of the rear sub-group frame 54.
From the rear sub-group frame 54 (FIG. 21).
(F)) Finally, the follower protrusion 54a is engaged with the follower stabilizing concave portion 53e to be in a stable state (FIG. 21).
(G)). Follower protrusion 54a and follower stable recess 53
Since four e are formed at equal angular intervals in the circumferential direction, eccentricity of the front sub-group frame 53 and the rear sub-group frame 54 is eliminated by engaging all of them. Thus, the switching from the tele-side approach state to the wide-side separation state is completed, and the first sub group S1 is separated from the second sub group S2 (separation movement end). No further rotation of the drive ring 55 in the same direction is possible.

When the switching to the wide-side separation state is completed, the drive ring 55 rotates in the reverse direction. Then, the driven projection 54
e (rear sub-group frame 54) moves rearward in accordance with the wide-side focus lead surface 55e, so that the linear guide protrusion 54
d enters the wide-side straight guide groove 51d and allows only the straight movement in the optical axis direction. This tele-side focus lead surface 5
By the integral movement of the rear sub-group frame 54 and the front sub-group frame 53 at the separated moving end by 5d, focusing on the wide side from the intermediate focal length to the short focal length end is performed (FIG. 21).
(H)).

Then, the rotation applying surface 55c is
When the drive ring 55 rotates until it comes into contact with the driven surface N1 of e, the rectilinear guide protrusion 54d of the rear sub-group frame 54 comes off the tele-side rectilinear guide groove 51d, and returns to the beginning of the description (FIG. 2).
1 (A)).

FIG. 22 shows the tele-focus lead surface 55d and the wide-focus lead surface 55d of the drive ring 55.
The focus principle by e is shown. Rear subgroup frame 5
When the drive ring 55 rotates within its tele-side focus area pt (from the infinity shooting position ∞ to the shortest shooting position n) with the cylindrical surface N3 of the driven projection 54e of No. 4 abutting on the telescopic focus lead surface 55d. , Straight guide groove 5 on the tele side
The rear sub-group frame 54 (and the front sub-group frame 53 (the first sub-group S1 and the second sub-group S2)) whose rotation is restrained by the engagement between 1f and the linear guide lug 54d integrally advance and retreat in the optical axis direction. Focusing is performed. Similarly, with the cylindrical surface N3 of the driven projection 54e in contact with the wide-side focus lead surface 55e, the drive ring 55 rotates within its wide-side focus area pw (from the infinity shooting position ∞ to the shortest shooting position n). Then, the rear sub-group frame 54 (and the front sub-group frame 53 (the first sub-group S1 and the second sub-group S2) whose rotation is restricted by the engagement of the wide-side straight guide groove 51d and the straight guide protrusion 54d. Are integrally moved in the optical axis direction to perform focusing.

More specifically, focusing on the tele side and the wide side is performed at a position where the rectilinear guide protrusion 54d of the rear sub-group frame 54 abuts on the rotation regulating surface 51a or 51b (a position where the rotation direction of the drive ring 55 is reversed). ) Is controlled by controlling the number of pulses counted by the pulsar of the drive system that drives the drive ring. For example, the number of pulses of the drive system for moving the focus lens group (sub-groups S1 and S2) from this reference position to the shortest imaging position n, the infinity imaging position ∞, and an arbitrary subject distance is determined by the focus lead surfaces 55d and 55e. Can be known in advance in consideration of the lead angle, etc., and by controlling the number of these pulses, it is possible to perform focusing according to the subject distance information. In the illustrated embodiment, the tele-side focus lead surface 55d and the wide-side focus lead surface 55e of the drive ring 55 have opposite inclinations with respect to the circumferential direction and have the same absolute value, and the driven protrusion 54e has a pair of circumferentially spaced apart. The driven surfaces N1, N2 are symmetrical with respect to the center in the circumferential direction. For this reason, focusing on the tele side and the wide side can be performed on the same basis, and there is an advantage that control is facilitated.

FIG. 17 shows a state in which the front sub-group frame 53 (first sub-group S1) and the rear sub-group frame 54 (second sub-group S2) are focused on infinity in the wide-angle state, and FIG. 19 shows a focusing state at the shortest photographing distance in the remote state, FIG. 19 shows a focusing state at infinity in the close state on the telephoto side, and FIG. The positional relationship between the sub group frame 54, the drive ring 55, and the front shutter holding ring 51) is shown. (A) of each drawing is a drawing in which these components are separated in the optical axis direction, and (B) is a drawing of an actual operation state.

A gear 55g is formed all around the rear end outer peripheral surface of the drive ring 55. As shown in FIGS. 12, 29, and 30, the gear 55g is meshed with the reduction gear train 63a for switching and focusing, and is driven to rotate forward and reverse by a forward / reverse drive motor 64 having a pulsar (encoder) 64p. Pinion 6 of forward / reverse drive motor 64
A relay gear 64q is provided between 4r and the pulsar 64P. Switching and Focusing Reduction Gear Train 63
“a” is sandwiched between the front shutter holding ring 51 and the gear holding ring 56, and the forward / reverse drive motor 64 is held by the rear shutter holding ring 52. Gear 5 of drive ring 55
5g is formed on the entire circumference, so that the three sets of control recesses 55a and the three driven projections 54e of the rear sub-group frame 54 can be easily engaged at different relative rotation positions every 120 °. become.

The lens shutter 57 and the aperture mechanism 58 are mounted on the rear shutter holding ring 52. That is, as shown in FIG. 12, FIG. 15, and FIG.
7 includes a shutter sector support plate 57a, three shutter sectors 57b, and a shutter drive ring 57c for driving the shutter sector 57b to open and close. The diaphragm mechanism 58 includes a diaphragm sector support plate 58a and three diaphragm sectors 5.
8b and an aperture drive ring 58c for opening and closing the aperture sector 58b.
7d, it is supported by the rear shutter holding ring 52. As is well known, the shutter sector 57b and the aperture sector 58b have a pair of dowels, one of which is a support plate 57b.
a, 58a rotatably supported, and the other is
7c and 58c are rotatably fitted. The lens shutter 57 opens and closes the opening of the shutter sector 57b by reciprocating rotation of the shutter drive ring 57c, and the aperture mechanism 58 adjusts the size of the aperture formed by the aperture sector 58b by the rotation of the aperture drive ring 58c. Change.

A sector gear 57g is formed on a part of the outer periphery of the shutter drive ring 57c, and this sector gear 57g meshes with a shutter drive reduction gear train 63b from a shutter drive motor 57m (FIG. 1).
2). When the shutter drive motor 57m is driven to rotate in the forward and reverse directions, the opening closed by the shutter sector 57b opens momentarily and closes again. In the present zoom lens barrel, the shutter sector 57b is a blade that has both a variable aperture function for determining an arbitrary aperture value and a shutter function, and an opening amount (aperture) of the shutter sector 57b according to the exposure value at the time of shutter release. Value) and the opening time (shutter speed) change.
7 m is controlled. The aperture driving ring 58c has a driven projection 58g on its outer periphery, and the driven projection 58g is engaged with an aperture control cam groove 48s formed on the inner peripheral surface of the linear guide ring 48 (FIG. 10). For zooming, the straight guide ring 48 and the rear shutter holding ring 52 (aperture drive ring 58c)
Moves relatively in the optical axis direction. Then, the aperture control cam groove 48
The driven projection 58g is moved in the circumferential direction according to s, the aperture driving ring 58 is rotated by a predetermined angle, and the size of the opening formed by the aperture sector 58b is changed. The aperture sector 58b is provided in order to regulate the maximum value of the photographing aperture diameter particularly at the wide-side photographing distance, and the opening amount is mechanically (forced) opened according to the extended state of the entire zoom lens barrel. Changes.

The zooming motor 4 for driving the cam ring 44
6, the forward / reverse drive motor 64 for driving the drive ring 55 and the shutter drive motor 57m of the lens shutter 57
As shown in FIG. 1, it is controlled by the control circuit 66. The control circuit 66 includes focal length information 67 set by the operator via a zoom switch or the like, subject distance information 68 detected by distance measuring means or photometric means, subject luminance information 69, and a cam by the focal length detecting means 46C. The rotational position information of the ring 44 and the rotational position information of the motor 64 by the pulser 64p are input, and according to the information, exposure is performed under a correct exposure condition with a set focal length.
The zooming motor 46, the forward / reverse drive motor 64, and the shutter drive motor 57m are controlled. In the illustrated embodiment, the shutter sector 57b doubles as a shutter and a variable aperture, and the aperture sector 58b performs only the restriction of the photographing aperture diameter at the time of wide-angle photographing. The variable aperture mechanism may be of a type that can freely change the size of the aperture. In this case, the aperture drive ring 58c may be rotated by an independent motor or manual operation.

In this embodiment, the focal length detecting means (rotating position detecting means of the cam ring 44) 46C detects the rotating position of the cam groove 44f corresponding to the connection line CC (FIG. 1), and the control circuit 66 determines at least In this section, the cam ring 44 is not stopped. In the step zoom mode, the stop position of the cam ring 44 is controlled stepwise. As described above, the drive corresponding to the set focal length, the subject distance, the subject brightness, and the like of the zoom lens barrel (photographing optical system) having the above-described switching group is completed immediately before the shutter release is performed. The focal length set by the operator may be confirmed at least by a finder optical system (not shown) separate from the photographing optical system.

In the zoom lens barrel using the above-described switching group lens barrel, the stop positions of the switching group frame, the first sub-group frame, and the second sub-group frame at the time of photographing are set in steps on the zooming basic locus. It is practical to be wise.

The mechanical structure of the above lens barrel is shown in FIG.
This is applied to the first variable power lens group 10 in the mode of FIGS. 8 and 9, but is applied to the second variable power lens group 2 in the mode of FIG.
0, the second zoom lens group 20 in the embodiment of FIG. 3, the first zoom lens group 10 in the embodiment of FIG. 4, the first zoom lens group 10 in the embodiment of FIG. 5, and the first zoom lens in the embodiment of FIG. The present invention can also be applied to the lens group 10 and the first variable power lens group 10 of the embodiment of FIG. 7 (the first lens L1 and the third lens L3 are integrated).

[Explanation of the Characteristic Portion of the Present Invention] In the above embodiment, the characteristic portion of the present embodiment is that the speed reduction gear train for switching and focusing sandwiched between the front shutter holding ring 51 and the gear holding ring 56. 63a (hereinafter simply referred to as a reduction gear train 63a).

As shown in FIGS. 12, 29 and 30,
The reduction gear train 63a is provided with a pinion 6 of the forward / reverse drive motor 64.
From the first gear 63a-1 meshing with the driving ring 5r.
The tenth gear 63a-10 is meshed with the fifth gear 55g. Of these, the first gear 6
3a-1, the second gear 63a-2, and the tenth gear 63a-
Reference numeral 10 denotes a spur gear having a constant outer diameter, and a third gear 63.
Each of the a-3 to ninth gears 63a-9 is configured as a double gear having large and small gears. Each of the double gears 63a-3 to 63a-9 meshes a large-diameter gear with a previous gear (a gear on the forward / reverse drive motor 64 side, a gear on the driving side) in the driving force transmission sequence, and The next gear in the same order (the gear on the drive ring 55 side, the gear on the driven side) is meshed.

Further, the third gear 63a-3 to the sixth gear 63a-6 are the same gear, respectively, and the third gear 63a-3 (first gear) and the fifth gear 63a-5 (second gear) ) Are rotatably supported independently by a common rotation center shaft 63m (first rotation center shaft).
3a-4 (third gear) and sixth gear 63a-6 (fourth gear) share a common rotation center axis 63n (second rotation center axis)
Independently rotatably supported. Rotation center shaft 63
m and 63n are parallel to each other, and their extending directions are parallel to the motor shaft of the forward / reverse drive motor 64. A reduction gear train 63a including the rotation center shafts 63m and 63n.
Are also parallel to each other. That is, the gears 63a-1 to 63a- of the reduction gear train 63a
Each 10 is rotated about a parallel rotation center. The rotation center of each of the gears 63a-1 to 63a-10 is parallel to the photographing optical axis of the zoom lens system.

The third supported by the common rotation center shaft 63m
The set of the gear 63a-3 and the fifth gear 63a-5 and the set of the fourth gear 63a-4 and the sixth gear 63a-6 supported on the common rotation center shaft 63n are positioned in the axial direction of the rotation center shaft. The small-diameter gear of the gear on the driving side relatively meshes with the large-diameter gear on the driven side. Specifically, among these four gears, the small diameter gear of the third gear 63a-3 to which the rotational force of the forward / reverse drive motor 64 is transmitted first meshes with the large diameter gear of the fourth gear 63a-4,
Next, the small diameter gear of the fourth gear 63a-4 is replaced with the fifth gear 63a-
5, the small-diameter gear of the fifth gear 63a-5 meshes with the large-diameter gear of the sixth gear 63a-6. As a result, the third gear 63a-3 to the sixth gear 63
a-6, the pinion 64r of the forward / reverse drive motor 64
Of the third gear 63 on the side of the rotation center shaft 63m.
a-3 to the fourth gear 63a-4 on the rotation center shaft 63n side, and from the fourth gear 63a-4 again to the rotation center shaft 6n.
The power is transmitted to the fifth gear 63a-5 on the 3m side, and subsequently from the fifth gear 63a-5 to the sixth gear 63a-5 on the rotation center shaft 63n side.
Transfer to 6. That is, the rotational force of the forward / reverse drive motor 64 is
Power is transmitted alternately by the gears supported by the pair of rotation center shafts 63m and 63n without passing through the same gear a plurality of times.

According to the structure of the reduction gear train 63a, in particular, the four gears from the third gear 63a-3 to the sixth gear 63a-6.
In order to dispose the two gears, it is sufficient to secure substantially two gear disposition spaces in a circumferential direction around the optical axis (a plane direction perpendicular to the rotation center axis of the gear). Become. Therefore, the circumferential space required for disposing a predetermined number of gears can be reduced, and the degree of freedom in disposing the reduction gear train within the limited space increases. For example, in the zoom lens barrel of the present embodiment, as shown in FIG. 30, the pinion 64r of the forward / reverse drive motor 64 at the start position of the reduction gear train 63a and the drive ring 55 at the end position.
A space corresponding to the length of the forward / reverse drive motor 64 is secured between the gears 55g in the front-rear direction (extending direction of the gear rotation center axis), and the space in the front-rear direction of the lens barrel is also provided. It is desirable to use the gear train effectively. In the configuration of the above-described embodiment, since a plurality of gears are supported on the rotation center shafts 63m and 63n, the space in the front-rear direction of the lens barrel can be effectively used. The space occupied can be reduced.

In the above embodiment, each of the two rotation center shafts 63m and 63n supports two gears in total, but the present invention is not limited to the gears supported by two parallel rotation center shafts. This is true if the number is at least three. That is, if one rotation center shaft supports two gears X and Y, and the other rotation center shaft supports one gear Z so as to be rotatable, and Z is meshed with both X and Y, the gear X , Y overlap in the direction of the rotation center axis, so that the arrangement space of the three gears in the plane direction orthogonal to the rotation center axis can be reduced.

Conversely, three or more gears may be supported by the rotation center shaft. For example, if there is room in the axial direction, the seventh gear 63a-7 and the ninth gear 63a-7 in the embodiment can be used.
A gear corresponding to the gear 63a-9 is connected to one of the rotation center shafts 63.
m, the eighth gear 63a-8 and the tenth gear 63a
It is also possible to support a gear corresponding to -10 on the other rotation center shaft 63n. According to this configuration, the third gear 6
Eight gears from 3a-3 to the tenth gear 63a-10 can be substantially accommodated in two gear disposition spaces in the circumferential direction. In this case, the seventh gear 63a-7
The radial size of each of the subsequent gears is set to 63 m, 6
What is necessary is just to set so that it can be mutually meshed corresponding to the interval of 3n.

Further, the number of gears supported by each of the pair of parallel rotation center shafts may be different. For example, a gear corresponding to the seventh gear 63a-7 in the embodiment is supported on the rotation center shaft 63m, the number of gears supported on the rotation center shaft 63m is 3, and the number of gears supported on the rotation center shaft 63n is 2. It is also possible.

Further, the number of parallel rotation center shafts supporting a plurality of gears may be more than two. For example, the seventh gear 63a-7 and the ninth gear 63a-9 in the embodiment are rotatably supported by a common rotation center axis (referred to as Q1), and the eighth gear 63a-8 and the tenth gear 63a-10 are It may be rotatably supported by another common rotation center axis (referred to as Q2). In this case, four parallel rotation center axes 63
m, 63n, Q1 and Q2, the third gear 63a-3 and the fifth gear 63a-5, the fourth gear 63a-4 and the sixth gear 63a-6, and the seventh gear 63, respectively.
a-7 and the ninth gear 63a-9, and the eighth gear 63a-8 and the tenth gear 63a-10 are supported, so that the gear train can be more compactly arranged in the circumferential direction.

As exemplified above, the gear arrangement of the motor reduction mechanism according to the present invention is not limited to the illustrated embodiment.
Various aspects are possible. If the number of gears coaxially supported is increased, the space occupied by the reduction gear train in a plane orthogonal to the gear rotation center axis is reduced as described above. On the other hand, the space occupied by the reduction gear train in the direction along the rotation center axis increases. In the present invention, the number of gears coaxially supported or the number of rotation center shafts supporting a plurality of gears is adjusted in accordance with the actually obtainable space in which the gear train can be arranged, so that the reduction gear train is An optimal arrangement structure can be obtained.

The present invention is suitable for precision equipment such as a zoom lens barrel in which the arrangement of the reduction gear train is liable to be restricted. In particular, as in the above-described embodiment, the first sub-group and the second sub-group ( Switching group) to the approach position and the separation position,
In addition, it is effective to apply the present invention to a motor deceleration mechanism for integrally moving between the approach position and the separation position. However, the present invention can be applied to devices other than the motor speed reduction mechanism of the zoom lens barrel, and can be applied to devices other than the camera.

[0112]

As described above, according to the present invention, it is possible to obtain a motor speed reduction mechanism having a high degree of freedom in arrangement, and in particular, a compact arrangement space in a direction perpendicular to the center of rotation of the gear. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a basic zooming locus of a first embodiment of a zoom lens system having a switching group.

FIG. 2 is a diagram illustrating a basic zooming locus of a second embodiment of a zoom lens system having a switching group.

FIG. 3 is a diagram illustrating a basic zooming locus of a third embodiment of a zoom lens system having a switching group.

FIG. 4 is a diagram showing a basic zooming locus of a fourth embodiment of a zoom lens system having a switching group.

FIG. 5 is a diagram showing a basic zooming locus of a fifth embodiment of the zoom lens system having a switching group.

FIG. 6 is a diagram showing a basic zooming locus of a sixth embodiment of the zoom lens system having a switching group.

FIG. 7 is a diagram showing a basic zooming locus of a seventh embodiment of the zoom lens system having a switching group.

FIG. 8 is a diagram illustrating an example of a stop position during photographing of a constituent lens group of a zoom lens system having a switching group.

FIG. 9 is a diagram illustrating an example of the stop position and an example of an actual movement locus of the lens group.

FIG. 10 is a cross-sectional view showing an embodiment of a zoom lens barrel embodying the zoom lens system having the switching group shown in FIGS. 1, 8, and 9;

11 is a developed view of an inner surface of the cam ring, showing an example of a cam groove shape of the cam ring of the zoom lens barrel in FIG. 10;

FIG. 12 is an exploded perspective view around a switching group frame.

FIG. 13 is an exploded perspective view of a part around a switching group frame.

FIG. 14 is a perspective view of a part around the switching group frame in a different assembled state.

FIG. 15 is an upper half cross-sectional view of a first sub-group and a second sub-group of the switching group frame in a state of being separated on the wide side.

FIG. 16 is an upper half sectional view in the tele side approaching state.

FIG. 17 is a developed view (A) showing the positional relationship between the first and second sub-groups in the infinity in-focus state in the wide-side separation state, with the respective components separated in the optical axis direction. FIG. 7B is a developed view (B) of the actual engagement state.

FIG. 18 is a development view (A) showing the positional relationship between the first and second sub-groups in the state of focusing on the shortest photographing distance in the wide-side separation state, with the respective components being separated in the optical axis direction. (B) is a developed view (B) of an actual engagement state.

FIG. 19 illustrates a positional relationship between components of the first sub-unit and the second sub-unit in an infinity in-focus condition in a telephoto-side approaching condition.
FIG. 3A is a developed view (A) in which each component is separated in the optical axis direction, and FIG.

FIG. 20 is a developed view (A) showing the positional relationship between the first and second sub-groups in a focusing state at the shortest photographing distance in the tele-side approaching state, with the respective components separated in the optical axis direction. )
FIG. 7B is a developed view (B) of the actual engagement state.

FIG. 21 is a development view illustrating switching between a tele-side approach state and a wide-side separation state by forward and reverse rotation of a drive ring.

FIG. 22 is an explanatory diagram of focusing by a drive ring.

FIG. 23 is an enlarged development view of the face cam of the front sub-group frame.

FIG. 24 is a front sub-group frame with respect to a front shutter holding ring,
It is a development expansion view showing a relation between a rear subgroup frame and a drive ring.

FIG. 25 is a front view showing a relationship between a front sub-group frame and a front shutter holding ring as viewed from a line XXV-XXV in FIG. 14;

26 is an enlarged view of a part XXVI of FIG. 25.

FIG. 27 is a front view showing the relationship between the rear sub-group frame and the front shutter retaining ring as viewed from the direction of the line XXVII-XXVII in FIG. 14;

FIG. 28 is an enlarged view of a part XXVIII of FIG. 27;

FIG. 29 is a front view showing a reduction gear arrangement of a drive ring driving system held between a front shutter holding ring and a gear holding ring.

FIG. 30 is a developed plan view of FIG. 29.

FIG. 31 is a block diagram showing a control system of the zoom lens barrel shown in FIG.

[Explanation of symbols]

 L1 First lens group L2 Second lens group L3 Third lens group L4 Fourth lens group S1 First sub group S2 Second sub group S3 Third sub group S4 Fourth sub group 10 First variable power lens group 11 First Group frame 12 Movable sub group frame 13 Guide groove 20 Second variable power lens group 21 Second group frame 22 Movable sub group frame 23 Guide groove 41 Camera body 42 Fixed cylinder 43 Female helicoid 44 Cam ring 45 Male helicoid 46 Zooming motor 46C Focal length detection means 47 Pinion 48 Straight guide ring 49 Rear lens group frame 50 Switching group frame 51 Front shutter holding ring 51a 51b Rotation regulating surface 51d Wide side straight guide groove 51f Tele side straight guide groove 51p Center opening 52 Rear shutter holding ring 52a Thrust surface 53 Front sub-group frame 53a Straight guide rib 53b Guide hole 53c Contact / separation lead surface 3d annular light-shielding reinforcing rib 53e 53f follower stabilizing recess 54 rear sub-group frame 54a follower protrusion 54b inclined surface 54c annular light-shielding reinforcing rib 54d rectilinear guide protrusion 54e driven protrusion 55 drive ring 55a control recess 55b 55c rotation applying surface 55d tele-side focus lead Surface 55e Wide-side focus lead surface 55f Annular light-shielding reinforcing rib 55g Gear 56 Gear press ring 56q Fixing hole 56r Storage recess 57 Lens shutter 57a Shutter sector support plate 57b Shutter sector 57c Shutter drive ring 57d Sector press ring 57g Sector gear 57m Shutter drive motor 58 Squeezing mechanism 58a Squeezed sector support plate 58b Squeezed sector 58c Squeezing drive ring 58g Driven protrusion 59 Straight guide rod 60 Fixing bracket 61 Fixing screw 62 Compression coil spring 63a Switching and focusing reduction gear train 63a-1 to 63a-10 First to tenth gear 63b Shutter drive reduction gear train 63m 63n Rotation center shaft 64 Forward / reverse drive motor 64q Relay gear 64r Pinion 66 Control circuit 67 setting Focal length information 68 Subject distance information 69 Subject brightness information

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazunori Ishizuka 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Gaku Kogyo Co., Ltd. (72) Maiko Takashima 2-36, Maenocho, Itabashi-ku, Tokyo No. 9 F term in Asahi Kogaku Kogyo Co., Ltd. (reference) 2H044 BE02 BE08 DB02 DD08 3J009 DA17 EA04 EA05 EA11 EA21 EA35 EA44 EB01 EB13 FA23 5H607 AA00 BB01 CC01 CC03 CC05 DD17 EE31 EE36 FF01

Claims (8)

[Claims] 1. A motor speed reduction mechanism for transmitting a rotational force of a motor to a driving object, wherein at least two parallel rotation center axes are provided, and one of the two rotation center axes is made to have a different position in an axial direction to be independent. And at least two gears are rotatably supported by the other, and at least one gear is rotatably supported by the other. These gears are supported by the other rotation center shaft from the gear supported by one rotation center shaft. A motor reduction mechanism characterized in that the gears mesh with each other so that rotation is alternately transmitted to the gears. 2. The motor reduction mechanism according to claim 1, wherein the two rotation center shafts are independently positioned at different positions in the axial direction and independently support two gears so as to be freely rotatable. 3. The motor reduction mechanism according to claim 1, wherein each gear supported by the at least two parallel rotation center shafts is a double gear having a large diameter gear portion and a small diameter gear portion. A motor reduction mechanism in which a small-diameter gear portion of a double gear supported on the rotation center shaft of the second gear alternately meshes with a large-diameter gear portion of the double gear supported on the other rotation center shaft. 4. The motor reduction mechanism according to claim 3, wherein a large-diameter gear portion of the double gear meshes with a previous gear in the driving force transmission sequence, and a small-diameter gear portion engages a next gear in the same driving force transmission sequence. Motor reduction mechanism meshing with. 5. The motor reduction mechanism according to claim 1, wherein all gears supported by the at least two rotation center shafts are the same gear. 6. The first lens frame for supporting the first and second sub-groups, each of which optically functions at an approach position and a separation position, respectively, in the motor speed reduction mechanism according to claim 1. And a second lens frame; a forward / reverse drive motor; and the first and second lens frames are moved in and out of the optical axis direction or integrally moved in the optical axis direction according to the rotational drive of the forward / reverse drive motor. A motor frame reduction mechanism provided between the forward / reverse drive motor and the lens frame movement mechanism of the zoom lens barrel provided with a lens frame movement mechanism. 7. A motor deceleration mechanism for transmitting a rotational force of a motor to an object to be driven, comprising: a first and a second rotation center axis parallel to each other; A first gear and a second gear rotatably supported by the first gear; and a third gear rotatably supported by a second rotation center shaft, wherein the first gear is a third gear. Wherein the third gear is meshed with both the first and second gears. 8. The motor reduction mechanism according to claim 7, wherein the second rotation center shaft supports a fourth gear that is rotatable independently of the third gear. The second gear is a motor reduction mechanism that meshes with both the fourth gear and the third gear.