JPH07218810A - Zoom lens barrel - Google Patents

Abstract

PURPOSE:To smoothly move an engaging pin in a groove by a small driving force. CONSTITUTION:As for a zoom lens system lens barrel, a straight guide barrel 17 provided with a straight groove 21 extending in a direction nearly parallel to an optical axis and a parallel groove 22 extending in a peripheral direction nearly perpendicular to the optical axis and also having the end part connected with the end part of the straight groove 21, a zoom cam ring 19 provided with a cam groove 24 rotatably mounted on the outer peripheral part of the straight guide barrel 17 and provided with a prescribed propulsion angle and formed so that the end on a film side may be overlaid on one end of the parallel groove 22 in a collapsed state, and a photographic optical system connected with an engaging pin 30 for engaging the straight groove, 21, the parallel groove 22 and the cam groove 24 are provided. The lens barrel is formed so that at least the inner peripheral edge among the peripheral edge of the connection part 25 of the straight groove 21 and the parallel groove 22 may pass through the more interior part than the intersection position which is obtained when the straight groove 21 is almost orthogonally crossed with the parallel groove 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom type lens having a zoom type photographing lens (hereinafter referred to as "zoom lens") capable of telephoto to wide angle photographing by variably controlling the intervals of a plurality of lens groups. It concerns a lens barrel.

[0002]

2. Description of the Related Art In recent years, as a part of multi-functionalization of compact cameras, zoom lenses which can freely photograph from a telephoto to a wide angle have been used. Further, in order to meet the demand for smaller size and thinner shape, a retractable type in which a zoom lens is retracted into a camera body has been generalized.

In this type of zoom lens, at least two or more lens groups are arranged in the lens barrel so as to be movable in the optical axis direction, and focusing is performed by changing the distance between the lens groups. It is configured so that shooting can be performed at a magnification. The zoom type lens barrel includes the above lens groups,
It is composed of a rectilinear guide cylinder attached to the camera body side that supports these, and a zoom cam ring rotatably fitted to the outside of the rectilinear guide cylinder (Japanese Patent Laid-Open No. 4-42).
No. 278932).

FIG. 9 is a developed view showing an example of a straight guide cylinder and a zoom cam ring. The zoom cam ring 1A is for moving two lens groups in the optical axis direction (vertical direction in the figure), and a plurality of, for example, three cam grooves 2, 3 are alternately formed in the circumferential direction on the circumferential surface thereof. Has been done. Also,
Similar to the zoom cam ring 1A, the straight guide cylinder 1B is provided with a plurality of guide grooves 4 and 6 in the circumferential direction, which are close to the circumferential surface and extend parallel to the optical axis direction.

The cam groove 2 is for moving the first lens group near the subject direction (arrow 9 in the figure) along the guide groove 4 in the optical axis direction, and intersects the optical axis at a predetermined angle. An oblique zoom groove is formed. An engagement pin 5 provided on a lens holder that holds the first lens group is inserted and engaged in the cam groove 2 and the guide groove 4.

The cam groove 3 is for moving the second lens group far from the object along the guide groove 6 in the optical axis direction, and is formed in a substantially inverted V-shaped bent groove, and the zoom cam ring 1A. It includes a collapsible groove portion 3a extending in the circumferential direction of the optical axis parallel to the film surface, and a zoom groove portion 3b intersecting the optical axis at a required angle. An engaging pin 7 provided on a lens holder that holds the second lens group is inserted and engaged in the cam groove 3 and the guide groove 6.

The collapsible groove portion 3a is the W of the zoom cam ring 1A.
It is formed on the side of the end and its end (left side in the figure) a
Is located near the collapsing side end a of the cam groove 2. This is to make the distance between the two lens groups as small as possible in the retracted state to achieve a thin and compact camera. Inclination angle α of the zoom groove 3b (angle formed with the film surface)
Is set to be larger than the inclination angle β of the cam groove 2.

When the engagement pins 5 and 7 are in the retracted state, they are located at the retracted end position a of the cam grooves 2 and 3, respectively, and the zoom cam ring 1A is rotated from this position in the direction of arrow 8 in the figure. Since the rotation is restricted by the guide grooves 4 and 6, the cam grooves 2 and 3 are moved in the optical axis direction to the Wide end position (wide angle position) b to widen the distance between the two lens groups. Further, the distance between the lens groups is narrowed again as the lens moves from the Wide end position b to the Tele end position (telephoto position) c. Here, the rotation of the zoom cam ring 1A is performed by a drive motor incorporated in the camera body from the viewpoint of the quickness and operability of the zooming operation.

[0009]

However, the above-mentioned conventional zoom lens barrel has the following problems. In a compact camera equipped with this zoom lens barrel, in order to make it thin and compact, the
Minimize the distance between two lens groups, ideally about 0
Is desirable. However, due to the structure, it is often difficult to reduce the distance between the lens groups to zero. First, Wid
When the amount of collapsing from the end position b is large, or when the stroke amount from the wide end position b to the collapsing position is increased in order to make the camera body thin and compact, as shown in FIG. The length of the groove portion 3a becomes long.
Therefore, the wide end side b of the collapsible groove portion 3a is located at the cam groove 2
However, there is a problem in that it interferes with the retracted end side “a”.

Second, when the lens barrel diameter is reduced to make the camera compact, as shown in FIG.
The circumference length B of the zoom cam ring 1A is shorter than the circumference length A of the zoom cam ring 1A shown in FIG. In this case, if the cam grooves 2 and 3 having the same shape and size as those in FIG. 9 are formed, the rotation angle of the zoom cam ring 1A becomes large and the pitch of the cam grooves 2 and 3 becomes small, so that the collapsed end side a of both is There was a problem of interference.

Here, if the inclination angle β of the cam groove 2 is set to be large, the rotation angle of the zoom cam ring 1A with respect to the total stroke amount of the lens group can be made small, and the interference of the cam grooves 2 and 3 can be prevented. You can However, if the inclination angle β increases, the rotational load when rotating the zoom cam ring 1A increases, which requires a drive motor with a larger driving force, which hinders size reduction.

In order to solve the above problems, the applicant of the present invention has proposed the following zoom lens barrel (Japanese Patent Application No. 5-160036). 7 and 8 show
It is a development view of a straight guide cylinder 17 and a zoom cam ring 19 showing the shapes of the guide groove and the cam groove of this zoom type lens barrel, and the positional relationship between them, respectively.
It shows the state. The linear guide tube 17 has a guide groove 21 formed substantially parallel to the optical axis and a parallel groove 2 formed substantially orthogonal to the optical axis (generally parallel to the film surface).
2 and the film side end 21a of the guide groove 21 intersects with the guide groove 20 side end of the parallel groove 22. On the other hand, the cam grooves 23 and 24 provided on the zoom cam ring 19 are zoom grooves formed in a substantially straight diagonal line intersecting the optical axis at a predetermined angle. When the lens barrel is collapsed, the right end of the parallel groove 22 and the film side end of the cam groove 24 are formed to overlap each other. By forming in this way, W
Even if the stroke from the side position to the retracted position is increased, the interference between the cam grooves 23 and 24 is eliminated, the thickness of the camera can be reduced, and the outer diameter of the lens barrel can be reduced. .

However, the zoom cam ring 19 is rotated in the direction of arrow 40, and the engagement pin 30 moves from the parallel groove 22 to the guide groove 2.
When moving to 1 (FIG. 8), the moving direction suddenly changes by 90 °, so that the engaging pin 30, the guide groove 21, and the parallel groove 2
Depending on the amount of backlash with 2, the sliding resistance applied to the engagement pin 30 may increase. Therefore, the zoom cam ring 19
It is necessary to set the driving force of the drive motor for rotating the motor to a certain degree. Therefore, a small drive motor cannot be used, which is an obstacle to downsizing the device.

The present invention has been made to solve the above problems, and further improves the above invention,
An object of the present invention is to enable the engagement pin to move smoothly between the straight groove and the parallel groove even with a small driving force.

[0015]

In order to achieve the above object, the first solving means of the zoom type lens barrel according to the present invention is a straight groove (21) extending in a direction substantially parallel to the optical axis. And a straight guide cylinder (17) extending in a circumferential direction substantially perpendicular to the optical axis and having a parallel groove (22) whose end is connected to the end of the straight groove, and an outer peripheral portion of the straight guide cylinder. Is rotatably attached to and has a predetermined pushing angle,
A zoom cam ring (19) having a cam groove (24) formed so that its film side end overlaps with one end of the parallel groove in the collapsed state; and a zoom cam ring (19) provided in the straight guide cylinder.
An imaging optical system (15), which is connected to the straight-moving groove, the parallel groove, and an engaging portion (30) that engages with the cam groove, and is moved in the optical axis direction by rotation of the zoom cam ring; At least the inner peripheral edge of the periphery of the connecting portion (25) between the straight-moving groove and the parallel groove is formed so as to pass through a position inside the intersection point when the straight-moving groove and the parallel groove are substantially orthogonal to each other. It is characterized by

In a second solving means according to the first solving means, the groove width of the connecting portion between the rectilinear groove and the parallel groove is formed larger than the groove width of the rectilinear groove and the groove width of the parallel groove. It is characterized by

In a third solving means according to the first or second solving means, at least the inner peripheral edge of the peripheral edge of the connecting portion between the straight-moving groove and the parallel groove is formed in a substantially arc shape. Is characterized by.

[0018]

In the solution according to the present invention, when the engaging portion moves in the connecting portion of the straight groove and the parallel groove, the resistance applied to the engaging portion is smaller than that when the engaging portion and the parallel groove are orthogonal to each other. . Therefore, the engaging portion can be smoothly moved within the straight groove and the parallel groove, and the zoom cam ring can be rotated with a small driving force.

[0019]

An embodiment of the present invention will be described below with reference to the drawings. 1 to 3 are cross-sectional views showing a configuration of a camera to which an embodiment of the zoom lens barrel of the present invention is applied, respectively, a retracted state, a wide end state, and Tel.
The e-edge state is shown. 1 to 3, inside the camera body 10, a camera body 11, a zoom lens barrel 12, a photographic film 13, and first and second lens groups forming a zoom lens of a photographic optical system. 14 and 15 are provided. An aperture 16 is provided substantially in the center of the camera body 11, and a straight guide tube 1 integrally provided with the aperture 16 is provided on the front side (left side in the drawing) of the aperture 16.
7 has been extended. On the rear side (right side in the figure) of the aperture 16, a film passage 1 through which the photographic film 13 travels.
8 are provided.

The zoom type lens barrel 12 includes a straight guide cylinder 17, first and second lens groups 14 and 15 arranged in the straight guide cylinder 17 and movable in the optical axis L direction, and a straight guide. It is composed of a zoom cam ring 19 rotatably attached to the outer periphery of the cylinder 17, a drive motor (not shown) for rotationally driving the zoom cam ring 19, and the like.

FIGS. 4 and 5 are development views of the straight guide cylinder 17 and the zoom cam ring 19 showing the shapes of the guide groove and the cam groove and the positional relationship between them, respectively.
The e-edge state is shown. In FIG. 4, the linear guide cylinder 1
The first and second guide grooves 20 and 21 are formed on the circumferential surface of No. 7 at equal intervals in the circumferential direction (horizontal direction in the drawing). Although not shown in FIG. 4, a plurality of (eg, three) first and second guide grooves 20, 21 are provided in the circumferential direction.
Has been formed.

The first guide groove 20 is a rectilinear groove substantially parallel to the optical axis L and regulates the rotation and movement stroke of the first lens group 14 around the optical axis. Similarly, the second guide groove 21 is a rectilinear groove parallel to the optical axis L and is formed close to the first guide groove 20. Further, the film side end of the second guide groove 21 (lower side in the drawing) is orthogonal to the axis of the straight guide cylinder 17, in other words, the photographic film 13 is formed.
A parallel groove 22 that is parallel to the first guide groove 20 extends in the opposite direction. Further, the end of the parallel groove 22 on the first guide groove 20 side is connected to the end of the second guide groove 21 on the film side (connecting portion 25). Further, the inner peripheral edge of the connecting portion 25 is formed in a substantially arc shape so as to pass through a position inside the intersection point when the inner peripheral edges of the first guide groove 21 and the parallel groove 22 are substantially orthogonal to each other. . Therefore, the groove width of the connecting portion 25 is formed larger than the groove widths of the first guide groove 21 and the parallel groove 22.

The first lens group 14 is arranged on the first lens holder 26 via a shutter 27. First
The lens holder 26 is slidably fitted into the straight guide cylinder 17, and the three engaging pins 28 protruding from the outer peripheral surface of the rear end portion are respectively inserted into the first guide grooves 20. , Only the movement in the optical axis direction is allowed, and the rotation is restricted.

The second lens group 15 is held by the second lens holder 29 and is arranged behind the first lens group 14. The second lens holder 29 is the straight guide tube 1
The three engaging pins 30 slidably fitted in the second lens holder 7 and located at the rear side of the first lens holder 26 and projecting from the outer peripheral surface of the rear end portion are respectively inserted into the second guide grooves 21. By doing so, only the movement in the optical axis direction is allowed and the rotation is restricted. A compression coil spring 32 is attached between the first lens holder 26 and the second lens holder 29 to bias the second lens group 15 rearward and prevent the rattling.

The zoom cam ring 19 has a flange portion 19a integrally formed on the outer peripheral surface of the end portion on the side of the photographic film 13, and is rotatably fitted to the outer periphery of the straight guide cylinder 17 so that the flange portion 19a is formed. It is slidably held by the front surface of the camera body 11 and a ring-shaped pressing member 33. Further, the flange portion 1 is formed on the outer peripheral surface of the zoom cam ring 19.
A gear 34 is formed in the vicinity of 9a, and first and second cam grooves 23, 24 are alternately formed on the inner peripheral surface at equal intervals in the circumferential direction, as shown in FIG. Although not shown in FIG. 4, a plurality of (for example, three) first and second cam grooves 23, 24 are formed in the circumferential direction.

The first cam groove 23 is provided in the first lens group 14
For moving in the direction of the optical axis L along the first guide groove 20 of the straight guide cylinder 17, and is formed as an oblique zoom groove intersecting the optical axis L at a predetermined angle.
The distal end portion of the engaging pin 28 that is inserted into is inserted and engaged. On the other hand, the second cam groove 24 is for moving the second lens group 15 in the optical axis L direction along the second guide groove 21, and is an oblique zoom groove similar to the first cam groove 23. And the engaging pin 3 formed in the second guide groove 21 and inserted into the second guide groove 21.
The leading end of 0 is inserted and engaged.

In FIG. 1, the pressing member 33 is a screw 3
A gear 36, which is fixed to the front surface of the camera body 11 by 5 and engages with the gear 34 of the zoom cam ring 19, is rotatably supported. The gear 36 is rotated by a drive motor (not shown) during the zooming operation, thereby rotating the zoom cam ring 19 in the extending direction or the retracting direction of the lens groups 14 and 15.

In the zoom type lens barrel 12 having such a structure, in the retracted state shown in FIG. 1, the first lens holder 26 is completely retracted into the straight guide cylinder 17 to form a retractable camera. ing. At this time, the first
The engaging pin 28 of the lens holder 26 is located at the film side end of the first guide groove 20 as shown in FIG. 4, and the engaging pin 30 of the second lens holder 29 is at the tip of the parallel groove 22. It is located at the film side end a of the second cam groove 24.
In this state, when the zoom cam ring 19 is rotated in the feeding direction (the direction of arrow 40 in FIG. 4) by the drive of the drive motor, the first cam groove 23 moves to the left side in the figure as shown in FIG. The engagement pin 28 is pressed by the groove wall surface of the first cam groove 23, and the component force thereof moves along the first guide groove 20 toward the subject. Therefore, the first lens group 14 also moves forward integrally with the first lens holder 26, and projects outward from the linear guide cylinder 17.

As a result of the above driving, the second cam groove 24 also moves to the left side in the figure as shown in FIG. 5, and when the zoom cam ring 19 is rotated by the length of the parallel groove 22, the second cam groove 24 is moved to the second position. The end of the cam groove 24 on the film side overlaps with the connecting portion 25,
The engagement pin 30 moves to the Wide end position b. In this case, since the parallel groove 22 is formed parallel to the surface of the photographic film 13, the engaging pin 30 cannot be moved forward along the second guide groove 21, and therefore the second lens group No. 15 remains at the collapsed end position. As a result, the first and second lens groups 14 and 15 are set to the Wide end state (FIG. 2).

In the Wide end state of FIG. 5, when the zoom cam ring 19 is further rotated in the feeding direction, the engaging pins 28 and 30 move toward the subject along the first and second guide grooves 20 and 21. The first and second guide grooves 20,
When moving to the Tele end position c of 21, the first and second lens groups 14 and 15 are set to the Tele end state (FIG. 3). When the drive motor is driven in the opposite direction to rotate the zoom cam ring 19 in the retracting direction, the engaging pins 28 and 30 are moved along the first and second guide grooves 20 and 21 to the photographic film 13. 1 and the first and second lens groups 14 and 15 are retracted into the straight guide cylinder 17, the collapsible state of FIG. 1 can be restored.

Here, in the present invention, the second guide groove 21
Since the inner peripheral edge of the connecting portion 25 between the parallel groove 22 and the parallel groove 22 is formed in a substantially arc shape and the groove width of the connecting portion 25 is further widened, when the engaging pin 30 moves in the connecting portion 25, the engaging pin The sliding resistance of 30 is reduced. Therefore, the load at the time of driving the zoom cam ring 19 can be reduced and the zoom cam ring 19 can be rotated more smoothly.

On the other hand, by forming only the inner peripheral edge of the connecting portion 25 into a substantially arc shape, the engaging pin 3 near the wide end is formed.
The backlash between 0 and the connecting portion 25 increases. However, after the zoom type lens barrel 12 is moved by the zooming operation,
Due to the control, in order to remove the backlash of the zoom cam ring 19, the zoom cam ring 19 always stops in the direction in which the first lens holder 26 is extended. Therefore, the engagement pin 30 has the connecting portion 25.
The second lens group 15 is pressed against the outer peripheral edge (outer side) of the second lens group 15, so that the position of the second lens group 15 does not vary.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment,
Various modifications are possible without departing from the spirit of the invention. For example, in the embodiment, both are two lens groups 14,
Although the zoom type lens barrel 12 having 15 has been described, the zoom type lens barrel 12 can be applied to one having three or more lens groups.

FIG. 6 is a view showing another embodiment of the shape of the connecting portion 25. In the figure, (a) shows that the outer peripheral edge of the connecting portion 25 is formed in a substantially arc shape like the inner peripheral edge. Therefore,
In this example, the groove width is substantially constant among the second guide groove 21, the connecting portion 25, and the parallel groove 22. In the figure, (b) shows that the inner peripheral edge of the connecting portion 25 is formed in a substantially straight line oblique to the second guide groove 21 and the parallel groove 22. In the figure, (c) has a further outer peripheral edge formed in a substantially oblique linear shape with respect to (b). As described above, the connecting portion 2
Even if 5, is formed, the engagement pin 30 can be smoothly moved between the second guide groove 21 and the parallel groove 22.

[0035]

According to the present invention, when the engaging portion moves in the connecting portion between the straight groove and the parallel groove, the resistance applied to the engaging portion is reduced so that the engaging portion can be smoothly moved. The zoom cam ring can be rotated with a small driving force. As a result, the drive motor can be downsized, and the camera can be made compact and lightweight.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a collapsed state of a camera configuration to which an embodiment of a zoom lens barrel of the present invention is applied.

FIG. 2 is a cross-sectional view showing a wide end state of the camera of FIG.

FIG. 3 is a cross-sectional view showing a Tele end state of the camera of FIG.

FIG. 4 is a diagram showing a shape of a guide groove and a cam groove and a positional relationship between them, in a collapsed state.

FIG. 5 is a diagram showing a Wide end state of FIG. 4;

FIG. 6 is a diagram showing another example of the shape of the connecting portion 25.

FIG. 7 is a diagram in a collapsed state showing the shapes of the guide groove and the cam groove proposed by the applicant of the present application and their positional relationship.

FIG. 8 is a diagram showing a Wide end state of FIG. 7;

FIG. 9 is a diagram showing an example of a conventional linear guide cylinder and zoom cam ring.

FIG. 10 is a diagram for explaining interference of cam grooves.

FIG. 11 is a diagram for explaining interference of cam grooves.

[Explanation of symbols]

 10 camera body 11 camera body 12 zoom type lens barrel 14, 15 first and second lens group 17 straight guide tube 19 zoom cam ring 20, 21 first and second guide groove 22 parallel groove 23, 24 first 1, Second cam groove 25 Connecting portion 28, 30 Engaging pin L Optical axis

Claims (3)

[Claims] 1. A straight groove extending in a direction substantially parallel to the optical axis,
And a straight guide cylinder extending in a circumferential direction substantially perpendicular to the optical axis and having parallel grooves whose ends are connected to the ends of the straight grooves, and rotatably attached to an outer peripheral portion of the straight guide cylinder. ,
A zoom cam ring having a predetermined pushing angle and having a cam groove formed so that a film side end thereof overlaps one end of the parallel groove in a collapsed state; and a zoom cam ring provided in the straight guide cylinder, A parallel groove and an engaging portion that engages with the cam groove, and a photographing optical system that is moved in the optical axis direction by the rotation of the zoom cam ring, the connecting portion between the rectilinear groove and the parallel groove. A zoom lens barrel, wherein at least an inner peripheral edge is formed so as to pass through a position inside an intersection point when the rectilinear groove and the parallel groove are substantially orthogonal to each other. 2. The groove width of the connecting portion between the straight groove and the parallel groove is larger than the groove width of the straight groove and the groove width of the parallel groove. Zoom type lens barrel. 3. The zoom lens mirror according to claim 1, wherein at least an inner peripheral edge of a peripheral portion of a connecting portion between the rectilinear groove and the parallel groove is formed in a substantially arc shape. Cylinder.