JPH05181046A - Zoom lenses - Google Patents

Abstract

PURPOSE:To obtain a zoom lens constituted of two groups of lenses which does not need a cam frame for moving the zoom lens. CONSTITUTION:This zoom lens is constituted of a 1st lens group 25 supported by a 1st moving frame 12 which moves by interlocking with driving and rotating a 1st motor 14, and a 2nd lens group supported by a 2nd moving frame 13 which moves singly by interlocking with driving and rotating a 2nd motor 15 provided in the 1st moving frame 12 and moves with the frame 12 when the motor 15 is stopped. Therefore, the diameter of a lens barrel is contracted as much as occupied by the cam frame and the lens barrel is miniaturized.

Description

Detailed Description of the Invention

[0001]

This invention relates to a camera for photography,
The present invention relates to a zoom lens used in optical equipment such as small-sized photographing machines, video cameras, copying machines, and enlargers.

[0002]

2. Description of the Related Art A zoom lens comprises a plurality of lens groups,
The position of each lens unit is displaced in the optical axis direction for zooming and focusing.

Specifically, it is constructed as a lens barrel having each lens group. For example, the cam frame includes a cam frame having a long and narrow cam hole along the circumference, a plurality of moving frames in which a cam follower protruding into the cam hole is fixed, and the cam frame is internally mounted to support a lens group. In many cases, the lens group is displaced in the optical axis direction to change the magnification by rotating and moving each moving frame.

Further, this type of zoom lens is provided with a moving frame which supports a lens group for focus matching, and the moving frame is moved by a driving means different from the above cam frame.
It is configured to perform caching.

[0005]

The conventional zoom lens as described above requires a cam frame for moving each moving frame, and this cam frame is required to have high accuracy in design and production. Therefore, it was a high-cost part.

Further, the lens barrel has a superposition structure of the cam frame and each moving frame, which is one of the factors for increasing the diameter of the lens barrel. From this, it is possible to downsize the camera and the like. It was an important issue.

The present invention has been made in view of the above circumstances, and an object thereof is to develop a zoom lens which does not use any cam frame.

[0008]

In order to achieve the above-mentioned object, in the present invention, a first lens group supported by a first moving frame which moves in conjunction with the rotational drive of a first motor, 1
A second lens group supported by a second moving frame which moves independently in association with the rotational drive of a second motor provided on the moving frame and moves together with the first moving frame when the second motor is stopped. We propose a zoom lens, which is characterized in that

[0009]

When zooming, first the first motor is driven to rotate. As a result, the first moving frame moves, the second moving frame also moves in the same direction along with the first moving frame, and the first and second lens groups are extended in the optical axis direction.

After extending the first and second lens groups to a predetermined position, the first motor is stopped and the second motor is rotationally driven. As a result, only the second moving frame moves,
The second lens group is displaced. After that, the second motor is stopped and the zooming is completed.

When focusing is performed, the first motor is rotationally driven after the zooming is completed as described above. As a result, the first and second lens groups are displaced together, so that the first motor is stopped at the in-focus point.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an example in which the present invention is implemented as a zoom lens of a camera will be described with reference to the drawings. FIG. 1 is a front view of a lens barrel of a zoom lens, and FIG. 2 is A- in FIG.
A sectional view taken along line A, FIG. 3 is a sectional view taken along line BB in FIG. 1, and FIG.
1A is a cross-sectional view taken along the line CC of FIG. 1, and FIG. 4B is an end view taken along the line DD of FIG. In these drawings, 11 is a fixed frame, 12 is a first moving frame, 13 is a second moving frame, 14 is a first motor, and 15 is a second motor.

The fixed frame 11 is a cylindrical frame body, and a flange 11a provided at the rear end of the fixed frame 11 is attached and fixed to the camera body. As shown in FIGS. 1 and 2, a helicoid screw (female) 11b is provided on the inner surface of the fixed frame 11, and a drive ring 16 provided inside the rear of the fixed frame 11 is screwed onto the helicoid screw 11b. is doing.

That is, the drive ring 16 is provided with a helicoid screw (male) 16a on its outer periphery, and this helicoid screw 16a is screwed into the helicoid screw 11b of the fixed frame 11. A gear 16b is engraved on the front outer periphery (the right end outer periphery in FIG. 2) of the drive ring 16, and the gear 16b is rotated by being interlocked with an output gear described later.

The drive ring 16 is connected to the first moving frame 12 by a friction spring 17. That is, the other end side bent portion of the friction spring 17 whose one end is fixed to the locking projection 12a of the first moving frame 12 is pressed against the rear surface of the drive ring 16. By this connection, the drive ring 16 that rotates according to the helicoid screw advances and retracts the first moving frame 12 that does not rotate. The friction springs 17 are provided at two positions above and below the drive ring 16 (FIG. 1). Further, the friction spring 17 has the first
Although it is configured separately from the moving frame 12, it may be configured integrally with the first moving frame 12.

On the other hand, on the inner surface of the fixed frame 11 described above, key grooves 11c linearly provided in the front-rear direction are provided at three equal positions, and each is provided around the rear end of the first moving frame 12. Key
12b is projected into these key grooves 11c.

The first moving frame 12 is a circular frame having a diameter slightly smaller than that of the fixed frame 11 and is installed in the fixed frame 11.
b is guided by the key groove 11c and moves in the optical axis direction (horizontal direction in FIG. 2) without rotating. That is, the helicoid screws 11b and 16a are pushed by the drive ring 16 which is rotated and moved, and also are pulled and moved in the optical axis direction without being rotated.

The drive ring 16 is, as detailed in FIG.
It is rotationally driven by an interlocking mechanism including an output gear 18, a reduction gear 19, a long gear 20, and a moving gear 21 of the first motor 14. The first motor 14 is a DC motor, which is attached to a fixed plate 22 provided on the fixed frame 11 and is pulse-controlled by using a photo interrupter 23. Note that 23
“A” indicates a photo chopper.

Further, a reduction gear 19 interlocked with the output gear 18 and an elongated gear 20 interlocked with the reduction gear 19 are pivotally supported by the fixed frame 11. Further, the moving gear 21 that is interlocked with the elongate gear 20 is pivotally supported by the bearing upright portion 12c provided on the first moving frame 12 so that the gear 21 meshes with the gear 16b of the drive ring 16. ..

By this interlocking mechanism, the rotational driving force of the first motor 14 is transmitted to the moving gear 21, and the moving gear 21
Causes the drive ring 16 to rotate. Therefore, the drive ring 16 moves according to the helicoid screws 11b and 16a, and moves the first moving frame 12 in the optical axis direction. At this time, the moving gear 21 moves along the elongate gear 20.

The shutter frame 2 is attached to the first moving frame 12 described above.
4, the front lens group 25 (first lens group) is supported by the cylindrical portion 24a of the shutter frame 24, and the shutter blade 24 and the shutter blade presser are provided near the rear surface side of the shutter frame 24. A blade 26 is provided. The shutter blades 26 are opened / closed by being interlocked with a motor drive source 27 arranged on the outer periphery of the cylindrical portion 24a.

The second motor 1 for moving and driving the second moving frame 13 is provided on the outer periphery of the cylindrical portion 24a of the shutter frame 24.
5 and its interlocking mechanism are provided. As shown in FIGS. 1 and 4 (A), this interlocking mechanism includes an output gear 28 of the second motor 15, reduction gears 29 to 32, an interlocking gear 33 fixed to the lead screw 34, and a second moving frame. It is composed of a cylindrical screw (female) 35 fixed to the upright portion 13 a of 13.

A pulse motor is used for the second motor 15, but it can be replaced with a DC motor using a photointerrupter as in the case of the first motor 14. The interlocking gear 33 rotates in association with the reduction gear 32 at the end. The interlocking gear 33 is fixed to one end of a lead screw 34 that extends through the shutter frame 24 and the upright portion 13a of the second moving frame 13 and is drawn rearward (upward leftward in FIG. 4A). is there.

The lead screw 34 has an enlarged diameter portion 34a.
The interlocking gear 33 sandwiches a part of the shutter frame 24 to prevent lateral movement. A tubular screw 35 is screwed into the lead screw 34, and the tubular screw 35 is screw-fed by the rotation of the lead screw 34, so that the second moving frame 13 is moved in the optical axis direction ( Figure 4 (A)
Left and right).

The second moving frame 13 is a cylindrical frame which is movable within the first moving frame 12, and a rear lens group (second lens group) 36 is supported on the cylindrical frame. Then, as shown in FIG. 4B, the second moving frame 13 is guided by the guide shaft 37 provided on the first moving frame 12 and is moved in the optical axis direction without being rotated. ..

That is, the shutter frame 2 is attached to the second moving frame 13.
The protruding arm 13b that protrudes forward (to the right in FIG. 4B) through the notch portion 24b of No. 4 is provided.
The guide shaft 37 is slidably passed through shaft holes formed in the upright piece portions 13c and 13d of 3b. The guide shaft 3
Numeral 7 is pivotally supported by shaft stoppers 12d and 12e projecting from the front and rear ends of the first moving frame 12 toward the inside of the frame.

The zoom lens described above operates as follows. First, when the main switch is off, FIG.
As shown in, it is in the retracted position. In other words, the rear lens group 36 is most retracted and the front lens group 25 is closest to the rear lens group 36.

When taking a picture, first, when the main switch is turned on, the first motor 14 is rotationally driven, and the first moving frame 12 is extended to a predetermined position (WIDE position), as shown in FIG. It becomes the state shown. That is, the rotational drive of the first motor 14 causes the moving gear 21 to rotate the drive ring 16, and the drive ring 16 moves forward according to the helicoid screw. Therefore, the first moving frame 12 is pushed by the drive ring 16 and is extended to a predetermined position.

The movement of the first moving frame 12 is divided and controlled by a gray code provided between the fixed frame 11 and the first moving frame 12, and the first motor 14 stops. In addition, the first moving frame 12
, The second motor 15 is stopped, so that the second moving frame 13 moves in the same direction as the first moving frame 12 and moves forward as shown in FIG. 5 (B). To do.

When the first moving frame 12 is extended to a predetermined position, the second motor 15 is rotationally driven. As a result, the interlocking gear 33 receives the rotational force to rotate the lead screw 34, so that the tubular screw 35 is screw-fed by the lead screw 34, and the second moving frame 13 moves backward, as shown in FIG.
The shooting becomes possible as shown in.

Since the operation shown in FIG. 5C is the WIDE photographing position, when photographing is performed in this state, the first motor 14 is driven and rotated by the release operation to perform focusing. That is, the distance measuring signal is converted into pulses by the control circuit, and the pulse signal is used to convert the first motor 14
To rotate. At this time, the front lens group 25 and the rear lens group 36 both move forward to perform focusing.

When performing zooming, FIG. 6 (A)
In the operating state of the WIDE position shown in FIG.
4 is driven to rotate, and as shown in FIG. 6B, the first moving frame 12 is extended toward the TELE position.

When the feeding position of the first moving frame 12 is determined, the first motor 14 is stopped, and the stopping position is detected by the gray coat. Based on this detection, the first moving frame 12 is detected. A position code (branch point detection) signal of the second moving frame 13 is output, and the control circuit determines the rotation direction of the second motor 15 and the pulse control time based on the position code signal.
The second motor 15 is driven to rotate. As a result, the second moving frame 13 moves to perform zooming, and the operation state shown in FIG. 6C is obtained at the TELE position.

Focusing is performed at the zoomed position by rotationally driving the first motor 14 in accordance with the release operation. At this time, the front lens group 25 and the rear lens group 36 both move forward to perform zooming.

In the TELE position, when distance measurement is performed at a distance closer than the closest position, the second motor 15 is rotationally driven in response to the release operation, and the rear lens group 36 is driven. Is moved to a predetermined position to perform telemacro focusing.

When the main switch is turned off, the second mode
The lens 15 is driven to rotate and the rear lens group 36 is moved to the front lens group 25.
, And this condition is detected in gray code. Then, in response to this detection signal, the first motor 14 is rotationally driven to cause the front lens group to retreat integrally, and is detected by the gray code at the most retracted position. The first motor 14 is stopped by this detection.

[0037]

As described above, since the zoom lens of the present invention does not require a cam frame, the lens barrel diameter can be reduced by the amount occupied by the cam frame, and as a result, optical equipment such as a camera can be used. It can be further miniaturized. Further, since this zoom lens can be housed in the camera body by bringing the first lens group and the second lens group close to each other,
If it is applied to a retractable camera, the length of the lens barrel can be shortened. Further, since this zoom lens does not have a cam frame which is expensive as a component, it becomes a zoom lens suitable for cost reduction. And, in particular,
In this zoom lens, focusing can be performed by moving the first and second lens groups, so that the zoom lens has good image performance.

[Brief description of drawings]

FIG. 1 is a front view showing a lens barrel of a zoom lens according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA in FIG.

3 is a sectional view taken along line BB in FIG.

4 (A) is a cross-sectional view taken along the line CC of FIG.
FIG. 4B is an end view taken along the line D-D in FIG. 1.

FIG. 5 is an explanatory view showing an operation process of moving the above-mentioned zoom lens to a photographing position.

FIG. 6 is an explanatory diagram showing a zooming operation process of the zoom lens.

[Explanation of symbols]

 11 Fixed Frame 11b Helicoid Screw 12 First Moving Frame 13 Second Moving Frame 14 First Motor 15 Second Motor 16 Drive Ring 16a Helicoid Screw 16b Gear 17 Friction Spring 21 Moving Gear 25 Front Group Lens (First Lens) Group) 33 interlocking gear 34 lead screw 35 cylindrical screw 36 rear group lens (second lens group) 37 guide shaft

Claims (1)

[Claims] 1. A first lens group supported by a first moving frame that moves in association with the rotational driving of a first motor and a rotational driving of a second motor provided in the first moving frame. And a second lens group supported by a second moving frame that moves independently and moves together with the first moving frame when the second motor is stopped.