JPH0279009A - Driving device for variable power lens - Google Patents

Abstract

PURPOSE:To obtain a variable power function close to that of a zoom lens and to eliminate the need for an expensive cam cylinder by moving a 1st moving lens which varies magnification stepwise and then moving a 2nd moving lens which makes correction corresponding to the moving position of the 1st moving lens stepwise. CONSTITUTION:The 1st moving lens 30 which varying the power is moved stepwise and the 2nd moving lens 30 which makes corrections corresponding to the moving position of the 1st moving lens 20 is also moved stepwise. Therefore, when the driving device for the variable power lens is put in operation, the 1st moving lens 30 is moved stepwise and the position of the 2nd moving lens 32 is shifted stepwise corresponding to the moving position of the 1st lens 30 and then determined. Consequently, the driving device for the variable power lens which has the variable power function close to that of the zoom lens, eliminates the need for an expensive cam cylinder, and contributes to cost reduction is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a driving device for a variable power lens of a photographic zoom lens used in a compact camera or the like.

[Prior Art] Modern compact cameras have a wide range of multifocal mechanisms equipped with zoom lenses. It controls the moving lens group.

[Problems to be Solved by the Invention] However, in order to accurately manufacture the cam cylinder, a sophisticated processing technique is required, resulting in a significant increase in cost.

On the other hand, a bifocal switching camera that combines a master lens and a converter lens does not require the above-mentioned cam barrel, so it has the advantage of being relatively inexpensive to configure, but it is difficult to switch the magnification desired by the photographer. I couldn't hope for it.

[Object of the Invention] The present invention has been made to solve the above-mentioned problems, and has a variable magnification function similar to that of a zoom lens, does not require an expensive cam barrel, and contributes to cost reduction. It is an object of the present invention to provide a driving device for a variable power lens.

[Means to solve the problem]

In order to achieve the above object, a variable power lens driving device of the present invention moves a first moving lens that performs zooming step by step, and performs correction corresponding to the moving position of the first moving lens. The second moving lens is moved in stages.

If the movement of the second movable lens is performed in stages by changing the relative position of the cam surface formed in stages and the abutment member that abuts it, the above object can be achieved with a simple structure. can be achieved.

[Effect]

According to the above configuration, when the variable power lens driving device of the present invention is operated, the first moving lens is moved in steps, and the position of the second moving lens is moved in steps corresponding to the moving position of the first moving lens. moved and determined.

Embodiments of the present invention will be described in detail below with reference to the drawings.

〔Example〕

In FIG. 2 showing a camera 1 using a variable power lens driving device according to an embodiment of the present invention, a fixed barrel 3 is attached to the front surface of a camera body 2, and a zoom lens 4 for photographing is held in the fixed barrel 3. A movable cylinder 5 is built in so that it can move forward and backward. Above the fixed barrel 3 is a finder window 6. Distance measurement windows 7a and 7b for autofocus and a photometry window 8 are provided.

A zoom finder (not shown) whose magnification changes in conjunction with the zooming operation of the zoom lens 4 is built into the back of the finder window 6. Further, a distance measuring light projecting element 9° and a light receiving element 10 (see FIG. 1) are housed in the depths of the distance measuring windows 7a and 7b.

Also, at the back of the photometry window 8, there is an EE that measures the brightness of the subject.
A sensor (for example, 5PD) 11 (see FIG. 1) is housed.

The zooming seesaw knob 12 is normally in the neutral position shown. When the index "T" side is pressed, the zoom lens 4 is zoomed toward the telephoto side only during the pressing period, and when the index "W" side is pressed, the zoom lens 4 is zoomed toward the wide-angle side.

Of course, if the pressure on the seesaw knob 12 is released during zooming, the zoom lens 4 stops zooming at that point. Further, a shutter button 13 is provided on the top surface of the camera body 2.

In FIG. 3 showing the structure of the zoom lens 4, the zoom lens 4 can be roughly divided into a movable barrel 5. It consists of a front group unit 14 that performs focusing to adjust the focus according to the subject distance and focus correction of the focus movement by changing the magnification, and a rear group unit 15 that changes the magnification of the image produced by the front group unit 14 and forms the image on the film surface. There is.

A projection member 16 and a pair of holding members 17 are provided on the outer periphery of the movable cylinder 5.
and is provided. A screw hole 16a is formed in the protrusion member 16, and a linear screw 18 for driving the movable barrel 5 in the optical axis direction is engaged with the screw hole 16a. Further, a long hole 17a is formed in the holding member 17, and a guide rod 19 for guiding the movable tube 5 in the optical axis direction is inserted through the long hole 17a. A spur gear 20 is attached to the end of the linear screw 18, and a zooming motor 22 is meshed with the spur gear 20 via a pinion gear 21.

Further, a contact plate 23 formed of a thin metal plate in a pattern is joined to the outer periphery of the movable cylinder 5.
A brush 24 that is slid by the brush 24 to detect the position of the movable cylinder 5 is attached to a partition plate 25 (see FIG. 1) that separates the camera body 2 from the brush 24 . This partition plate 25 has the guide rod 1
9 and the motor 22, a light-shielding tube 26 through which the movable tube 5 is moved in and out is attached. The linear screw 18 is rotatably mounted between the fixed cylinder 3 and the partition plate 25.

The brush 24 has three claws 24a and 24b.

24c, when the claws 24b and 24c are short-circuited by contacting the contact plate 23, when they are not short-circuited, and when the claws 24a and 24b are short-circuited, the claws 24a and 24c are short-circuited. In this case, five different combinations are obtained in which all three are short-circuited, and thereby the position of the movable cylinder 5 is detected in five stages.

In FIG. 4 showing the structure of the front group unit 1-14,
The front group unit 14 has a focusing lens (referred to as a lens 30) at its tip.
Behind the camera, a shutter block 31 equipped with a shutter control mechanism and a cam ring 33 for driving a lens (referred to as a second lens) 32 of the rear group unit 15 are provided.

The cam ring 33 has a cylindrical shape, and a stepped cam surface 33a is provided at one end thereof. This cam ring 33 can be made of plastic with a simple mold structure. A protrusion 34 provided on the outer frame of the second lens 32 is engaged with this cam surface 33a, and the position of the second lens 32 is regulated in stages based on the position of the movable tube 5. Each position of the second lens 32 is
It is determined to accurately focus on the film plane at each selected focal length.

Gear portions 33b and 33c are formed at the end of the cam ring 33 on the shirt block 31 side. Gear part 33
A tip 35a of a pawl member 35 for regulating the rotational position of the cam ring 33 is engaged with b. This claw member 35
is rotatably attached to a shaft 36 fixed to the shutter block 31. Furthermore, a spring 37 is provided at one end 35b of the claw member 35 for biasing the tip 35a toward the gear portion 33b.

An electromagnet 38 is provided near the end 35b. When electricity is applied to the electromagnet 38, the end portion 35b is attracted to the electromagnet 38, and the claw member 35 is rotated against the bias of the spring 37. As a result, the tip portion 35a is connected to the gear portion 3.
3b, and the restriction of the cam ring 33 is released. When the conduction to the electromagnet 38 is stopped, the claw member 35 is rotated by the action of the spring 37, and the tip portion 35a engages the gear portion 33.
b. In addition, conduction and non-conduction of the electromagnet 38 are as follows.
It is switched based on the position data of the movable cylinder 5 sent out from the brush 24.

A gear 39 for rotationally driving the cam ring 33 is meshed with the gear portion 33c, and this gear 39 is meshed with a motor 41 via a gear train 40 provided on the shutter block 31.

This motor 41 is a small, low-cost DC motor, and is driven based on position data of the movable cylinder 5.

Inside the shutter block 31, there is provided a feeding mechanism (not shown) that feeds out the first lens 30 based on distance measurement data obtained from the light receiving element 11.

A lever 42 that is rotated in conjunction with this feeding mechanism protrudes from the opening 31a, and a notch 43a that is engaged with this lever 42 is located at the ring-shaped outer circumferential portion 4 of the lunches 30.
It is formed in 3. Further, a threaded portion 44 is formed at the rear end of the outer peripheral portion 43, and this threaded portion 44 is engaged with a female thread 31b provided at the center of the shutter block 31.

In FIG. 1 schematically showing the structure of the camera 1, a CPU 47 is connected to the motor 22 via a driver 46 for driving the motor 22. As shown in FIG.

The second CPU 47 is operated according to the sequence program written in the program ROM 48. Also,
The CPU 47 includes the light projecting element 9. Light receiving element 10. EE
Sensor 11. Seesaw knob 12°Shutter button 1
3. A front group unit 14 and a brush 24 are connected.

To use the camera 1 configured as described above, first, a film is loaded into the film chamber of the camera 1, and the zoom lens 4 is directed toward the subject. While observing the subject through the zoom finder, operate the seesaw knob 12 to find the desired magnification. For example, when the index Tj side of the seesaw knob 12 is pressed, the CPU 47 sends a command to the driver 46 to drive the motor 22. The rotation of the motor 22 is transmitted to the linear screw 18 via the pinion gear 21 and spur gear 20. and moves the movable cylinder 5 in a direction in which it projects from the fixed cylinder 3.

At the same time, current is applied to the electromagnet 38 and the motor 41 is driven. By this, electromagnet 3
When the end portion 38b is attracted to the cam ring 8 and the claw member 35 is rotated to unlock the cam ring 33, the driving force of the motor 41 is transmitted to the gear 39 via the gear train 40.
The cam ring 33 begins to rotate.

As the movable cylinder 5 is moved, the contact plate 23 is also moved,
The pattern of the contact plate 23 that the brush 24 is in contact with changes. Once the desired magnification is determined, release the seesaw knob 12. The drive of the motor 22 is stopped, but at that time,
The claws 24a, 24b, 24c of the brush 24 are connected to the contact plate 23.
When you are not in contact with any of the five patterns,
The drive of the motor 22 is not stopped, but continues to be driven slightly, and is stopped when it comes into contact with the closest pattern.

Depending on the pattern at the stop position, the claws 24a, 2
4b and 24c is determined, and position data of the movable cylinder 5 is detected.

Based on this position data, the CPU 47 selects the front group unit 1.
4 to stop the conduction to the electromagnet 38, and also stop the magnet 41.

Therefore, the tip portion 35a engages with the gear portion 3.3b, the cam ring 33 is locked at the position corresponding to the stop position of the movable barrel 5, and the second lens 32 is locked at the position corresponding to the stop position of the movable barrel 5. will be stopped.

Next, when you press the shutter button 13 halfway, the distance measurement window 7
A light emitting element 9 for distance measurement provided at the back of a and 7b. The light receiving element 10 is activated to perform distance measurement. The CPU 47 drives the focusing mechanism based on distance measurement data from the light receiving element 10, performs focusing, and locks the focus. Thereafter, when the composition is determined and the shutter button 13 is further pressed, the CPU 47 opens and closes the shutter based on the photometric data from the EE sensor 11, and the loaded photosensitive material is exposed.

Note that stepping motors may be used as the motors 22 and 41, but even if a low-cost DC motor or the like, which is difficult to control precisely, is used, it is possible to control the lens position in a stepwise manner. be able to.

Furthermore, it goes without saying that the front group lens is not limited to the above-mentioned embodiment, and may be moved in steps by manual operation.

Although the two-group zoom lens system has been described above, it is of course possible to apply the idea of the present invention to other zoom lens types, and the desired effect can be obtained.

〔Effect of the invention〕

As described above, according to the variable power lens driving device of the present invention,
The first movable lens that performs magnification change is moved in stages, and the second movable lens that performs correction is moved in stages in accordance with the movement position of the first movable lens, so it is similar to a zoom lens. It is now possible to provide a variable power lens driving device that has a variable power function, does not require an expensive cam barrel, and can contribute to cost reduction. Furthermore, if the second movable lens is driven by changing the relative position between the cam surface formed in stages and the contact member that contacts it, the lens position at each focal length can be accurately controlled. In addition, the simple configuration can contribute to cost reduction.

[Brief explanation of the drawing]

FIG. 1 is a block diagram schematically showing a camera cedar employing an embodiment of the present invention. FIG. 2 is an external view of the camera shown in FIG. 1. FIG. 3 is an exploded schematic perspective view of a zoom lens employing the present invention. FIG. 4 is a partially exploded schematic perspective view of the zoom lens shown in FIG. 3. ■...Camera 4...Zoom lens 5...
・Movable cylinder 12...Seesaw knob 14...Front group unit 15...Rear group unit 22.41...Motor
23... Contact plate 24... Brush 30... Second lens 32... Shutter block 32... Second lens 33... Cam ring 33a... Cam surface 35...
Claw member 47...CPU.

Claims (2)

[Claims] (1) In a variable power lens driving device having at least two movable lenses, means for moving the first movable lens in stages, and means for moving the second movable lens in stages corresponding to the movement position of the first movable lens. 1. A driving device for a variable magnification lens, comprising a means for moving the variable magnification lens. (2) The second moving lens is moved in steps by changing the relative position of a cam surface formed in steps and a contact member that comes into contact with the cam surface. The variable power lens driving device according to item 1.