JPH05142461A - Zoom lens barrel - Google Patents

Abstract

PURPOSE:To make a rotational angle required for zooming small, to make the migration angle of a cam small, and to make torque at an inflection point where switching to macro-photography in which actuation becomes heavy is performed small as for a zoom lens barrel with macro-photographing function. CONSTITUTION:In the zooming lens barrel where zooming is performed by compositely moving helicoids 20a and 21a and a cam groove 19a by rotating a cam barrel 19 integrated with the male helicoid 20a, and which is moved by the cam or the holicoide in a front group sliding frame 14 to perform focusing; a macro groove communicating with a macro area is provided by being extended to an ordinary zooming area in the cam groove 19a of the cam barrel 19, and the shape of the macro groove is formed by shifting the position of the origin of a focusing mechanism 13 provided in the frame 14 by macro switching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens barrel of a zoom lens having a zooming mechanism and also a macro mechanism.

[0002]

In recent years, zoom lenses having a macro function have been provided and proposed.

The proposal according to Japanese Utility Model Laid-Open No. 2-5715 is related to a fixed barrel; a cam ring supported by the fixed barrel so as to move in the optical axis direction with rotation; A lens guide ring that moves integrally in the optical axis direction and that rotates relative to the cam ring as the cam ring moves in the optical axis direction; and a cam groove for at least two front and rear moving lens groups formed in the cam ring. A lens guide groove formed on the lens guide ring corresponding to these cam grooves; and a movable lens of at least two groups, front and rear, having guide pins inserted across both the lens guide groove and the cam groove. The cam groove and the lens guide groove are provided with a zooming section for moving the front and rear moving lens groups in a predetermined locus by a combined movement of the cam groove and the lens guide ring in the optical axis direction and relative rotation. Zoo And a macro transition section moving the further moving lens unit from ring end in the macro shooting area,
Moreover, the zoom lens barrel with the macro is characterized in that the zooming section and the macro transition section of the cam groove have lead angles in mutually opposite directions with respect to the direction parallel to the optical axis. is there.

In the structure adopting the combined movement of the cam groove and the helicoid which is the lens guide ring as in the above proposal, the cam groove advances in the direction parallel to the optical axis because the lens barrel unit advances when it is rotated to the macro end. The zooming section and the macro transition section have opposite lead angles,
The cam diagram is as shown in FIG.

Further, in the above proposal, since the base point position of the front lens group in the macro region by the focusing mechanism in the front lens group sliding frame is set to be the same as the zooming region, all the movements are made by the cam grooves. ing.

The above proposal has the following problems because it has such a configuration.

Since the cam groove has opposite lead angles in the direction parallel to the optical axis in the zooming region and the macro transition region, the angle formed by the lead angles becomes small. Therefore, when the cam pin moves in the cam groove, the torque at the inflection point increases, and the load required for shifting from zooming movement to macro becomes heavy.

If a method of increasing the lead angle is used to solve the problem that the zooming operation becomes heavy, the zoom rotation angle increases and the lens group must be moved further.

Due to the above relation, the zoom rotation angle and the lens group movement amount increase, and the transition time required for operation becomes longer when the motor is driven.

Since the base point position for focusing is the same base point position for zooming and macro, the amount of movement in the cam groove is further increased.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce a rotation angle required for zooming and a cam transition angle in a zoom lens barrel with a macro as compared with a conventional one, and an inflection point where operation becomes heavy. It is an object of the present invention to provide a zoom lens barrel in which the torque in the lens is reduced.

[0012]

The above object has at least two movable lens groups and comprises a fixed barrel, a helicoid female, a helicoid male, a cam barrel, a straight guide ring, a front group sliding frame and a rear group sliding frame.
In the zoom lens barrel for performing focusing by moving by the cam or helicoid in the front group sliding frame, zooming is performed by the combined movement of the helicoid and the cam groove by the rotation of the cam barrel integrated with the helicoid male. The cam groove of the cylinder is extended to the normal zooming area to provide a macro groove communicating with the macro area, and the macro mechanism is configured by shifting the base point position of the focusing mechanism provided on the front group sliding frame by macro switching. This is achieved by a zoom lens barrel characterized by the above.

That is, in the zoom lens barrel of the present invention, the rear group cam groove is provided so as to give only the helicoid movement amount to the lens group movement during macro photography (that is, it is orthogonal to the direction parallel to the optical axis). It is characterized in that a front group cam groove is provided in which a lens interval for the focal length with respect to the back focus and a focusing amount necessary for macro photography are added. Further, the cam groove of the cam barrel is usually extended to the zooming area to provide a macro area.However, in the present invention, the shift amount to the macro area is adjusted by shifting the base point position of the focusing mechanism to adjust the rotation angle required for zooming. It is configured to reduce.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a sectional shape of a zoom lens barrel according to the present invention, in which the upper part from the optical axis is wide and the lower part is telescopic. The lens consists of two groups,
The rear group lens unit 12 is on the side of the film F, which is the image forming plane,
In front of it is the front group lens unit 11. The front lens unit 11 is held by a focusing mechanism 13, and the mechanism is fixed to the front sliding frame 14. The rear group lens unit 12 is supported by the rear group sliding frame 15.

A front group cam pin 16 is attached to the front group sliding frame 14, and a rear group cam pin 17 is attached to the rear group sliding frame 15, and the cam pins 16 and 17 are linearly mounted on a linear guide ring 18. The guide groove and the cam groove 19a provided in the cam barrel 19 are engaged to maintain a sliding contact relationship. The cam groove 19a is provided with a macro groove which extends the tele portion of the zooming area and communicates with the macro tele portion of the macro area. Move in the axial direction.

A helicoid ring 20 is fixed to the cam barrel 19, and the helicoid ring 20 is provided with a gear and a helicoid male 20a on the outer peripheral portion. The helicoid male 20a has a flange focus adjusting function that is fixed to the camera body, and is in a meshed relationship with the helicoid female 21a provided on the inner circumference of the fixed barrel 21. Further, the fixed barrel 21 is provided with a zoom drive motor (not shown), the drive gear provided on the zoom drive motor meshes with the gear provided on the helicoid ring 20, and the helicoid is fitted by the rotation of the zoom drive motor. The helicoid ring 20 located at moves in the optical axis direction.

In order to prevent the straight guide ring 18 from rotating around the optical axis, a straight guide plate 22 is attached to an end surface of the straight guide ring 18 and is guided by a straight groove 21b provided in a fixed barrel 21. The linear guide plate 22 sandwiches the flange portion of the cam barrel 19 with the linear guide ring 18, and restricts the movement of the cam barrel 19 in the optical axis direction.

The zoom lens barrel described above is a cam barrel.
Although the zooming is performed by the combined movement of the helicoid and the cam groove by the rotation of 19, the macro position is shifted by shifting the base point position of the focusing mechanism 13 provided in the front group sliding frame 14 when the macro switching is performed. The groove shape is shown in FIG. 2, which shows the shape up to the macro region provided at the end of the cam groove 19a of the present invention. In the prior art shown in FIG. 6, the rotational movement angle of the cam barrel from the zooming zone end (tele) to the macro end (tele macro) was 18 °, but it is 9.5 ° in FIG. 2 of the present invention. .. This relationship will be described below.

FIG. 3 is a schematic view showing the lens movement of the zoom lens having the macro function and the movement of all the units, and FIG. 3A shows the telephoto state. (B) shows the state of the telemacro according to the prior art, (c)
Shows the state of the telemacro according to the present invention. In macro photography, the front lens unit 11 is generally moved forward from the telephoto state. However, in the present invention, as shown in (c), the entire lens barrel unit (all units 10) is moved leftward by the helicoid movement, so that the rear lens group unit 12 is left before the front lens group unit 11 reaches a predetermined position. It will move in the direction. For this reason, the cam diagram, which is the locus of the cam pin, has to move backward in both groups due to the helicoid movement amount as shown in FIG.

The present invention is characterized by the following improvements. The rear lens group unit 12 moves in the optical axis direction with respect to the camera body by the helicoid movement amount. That is, FIG.
As shown in the rear group cam diagram, the cam barrel 19 moves in the helicoid direction, and therefore the diagram is perpendicular to the optical axis. Then, the front group cam diagram may be a diagram that has moved by a predetermined feeding amount at that time. Due to this and the shift of the base point position described later, the moving angle to the close-up photographing area (18 °) shown in FIG. 6 in the prior art is about half (9.5 °) in the present embodiment shown in FIG. ing.

Next, the moving speed to the close-up photographing area will be examined. In FIG. 4, the vertical axis shows the amount of movement of the front lens group unit 11 on the cam diagram, and the horizontal axis shows the time axis. All the feeding amounts of the front lens unit unit 11 are added to the cam diagram. In this case (moving curve C41), not only the space in front of the cam barrel 19 becomes large, but also the front group cam pin 16 is impacted at the time of transition from the zoom use area to the close-up shooting area.

FIG. 5 shows the object distance on the horizontal axis and the amount of extension of the front lens group unit 11 on the vertical axis. It is possible to shoot from ∞ to 0.9 m during normal shooting and 0.9 during close-up shooting. Shooting is possible between m and 0.6 m. Since the number of steps required for close-up photography is smaller than the number of steps required for normal photography, the base position of the focusing mechanism,
That is, in the present embodiment, the front lens group unit 11 is previously moved out of the front lens group sliding frame 15 by shifting it by A relative to the ∞ position (base point position) in the zooming range, and the front lens group is moved by the cam barrel 19. The amount A is a supplement amount to the feeding amount of the cam barrel 19.

A curve C42 in FIG. 4 shows the amount of movement when the base point position is shifted by A. The movement time is shortened and the fluctuation of the load on the front group cam pin 16 is reduced, which occurs at the time of switching. Impacts can be avoided.

The amount A for shifting the base point position is AF
It is possible to set the optimum value according to the conditions from the relationship of the number of steps, the space of the cam barrel 19, the transition time from the zooming area to the close-up imaging area, and the like.

[0025]

As to the zoom lens barrel with the macro, by reducing the transition angle from the zooming range to the macro range, it is possible to avoid a large fluctuation of the torque at the inflection point, and it is possible to avoid the zooming drive. It is not necessary to increase the motor output unnecessarily, the camera equipped with the zoom lens barrel shortens the switching time from the zooming state to the close-up shooting area, and the shock generated at that time is not felt at all. It was

[Brief description of drawings]

FIG. 1 shows a sectional shape of an embodiment of a zoom lens barrel of the present invention.

FIG. 2 shows a cam groove shape according to the present invention.

FIG. 3 is a schematic diagram showing lens movement of a zoom lens and movement of all units.

FIG. 4 is a graph showing movement time on a cam diagram.

FIG. 5 is a graph showing a delivery amount of a front lens group.

FIG. 6 shows a cam groove shape according to a conventional example.

[Explanation of symbols]

 10 All units (lens barrel unit) 11 Front group lens unit 12 Rear group lens unit 13 Focusing mechanism 14 Front group sliding frame 15 Rear group sliding frame 16 Front group cam pin 17 Rear group cam pin 18 Straight guide ring 19 Cam barrel 19a Cam groove 20 Helicoid ring 20a Helicoid male 21 Fixed body 21a Helicoid female 21b Straight groove 22 Straight guide plate

Claims (3)

[Claims] 1. Having at least two movable lens groups,
Composed of fixed barrel, helicoid female, helicoid male, cam barrel, straight guide ring, front group sliding frame, rear group sliding frame, and combined movement of helicoid and cam groove by rotation of cam barrel integrated with the helicoid male. In the zoom lens barrel that is zoomed by, and is moved by a cam or helicoid in the front group sliding frame to perform focusing, the cam groove of the cam barrel extends into the normal zooming area and has a macro groove that leads to the macro area. A zoom lens barrel characterized in that the macro groove shape is configured by shifting the base point position of a focusing mechanism provided on the front group sliding frame by providing and macro switching. 2. The zoom lens barrel according to claim 1, wherein the base point position is an ∞ position in the zooming range. 3. The zoom lens barrel according to claim 1, wherein the rotation angle of the cam barrel from the end of the normal zooming region to the end of the macro is within 10 °.