GB2309548A

GB2309548A - Lens barrel having shutter mounted on linear movement barrel

Info

Publication number: GB2309548A
Application number: GB9701527A
Authority: GB
Inventors: Hiroshi Nomura; Kazuyoshi Azegami; Takamitsu Sasaki
Original assignee: Asahi Kogaku Kogyo Co Ltd
Current assignee: Pentax Corp
Priority date: 1996-01-26
Filing date: 1997-01-24
Publication date: 1997-07-30
Anticipated expiration: 2017-01-24
Also published as: GB9701527D0; GB2309548B

Abstract

A lens barrel (10, Fig 1) includes a rotational barrel 19 drivable so as to rotate about an optical axis of the lens barrel. The rotational barrel has a plurality of guide grooves 19c on its inner periphery. The lens barrel further includes a linear movement barrel 20 guidable along the optical axis without rotating about the optical axis, a unit 21 secured inside the linear moving barrel, and a plurality of follower pins 24 securing the unit to the linear movement barrel. The plurality of follower pins 24 each project outwardly from an outer periphery of the linear movement barrel 20 to engage with the plurality of guide grooves 19c, respectively, so that the linear movement barrel 20 is moved along the optical axis relative to the rotational barrel 19 when the rotational barrel is driven to rotate. Unit 21 may be shutter unit.

Description

LENS BARREL HAVING A SHUTTER THEREIN The present invention relates to a lens barrel having a shutter therein, and more particularly relates to a lens barrel which is provided with a movable moving barrel guidable along an optical axis without rotating about the optical axis, and a shutter unit fixed to the moving barrel.

A conventional lens-shutter type of zoom camera is well known, having a shutter-unit driving mechanism for moving a shutter unit, including a lens shutter consisting of a series of shutter blades, forwardly and rearwardly along an optical axis of a photographic lens system when a zoom lens barrel is driven to move forwardly and rearwardly along the optical axis, respectively.

It is also known to provide a shutter-unit driving mechanism with a rotational barrel and a linear moving barrel. The rotational barrel is provided with cam grooves on an inner periphery thereof, and is driven to rotate about the optical axis by rotation of a motor. The linear moving barrel is provided therein with a shutter unit and further provided thereon with follower pins respectively engaging with the aforementioned cam grooves of the rotational barrel. With this particular type of shutter-unit driving mechanism, the linear moving barrel, together with the shutter unit, is driven to move along the optical axis without rotating about the optical axis when the rotational barrel is driven to rotate.

Generally in such a shutter-unit driving mechanism, the shutter unit is fixed to the linear moving barrel by set screws or pins, each engaging with both the shutter unit and the linear moving barrel. However, such set screws or pins are used simply for the purpose of fixing the shutter unit to the linear moving barrel.

An object of the present invention is to provide a lens barrel having a shutter therein which has a fewer number of components than a similar conventional type of lens barrel.

According to an aspect of the present invention, there is provided a lens barrel including: a rotational barrel driven to rotate about an optical axis of the lens barrel, the rotational barrel having a plurality of guide grooves formed on an inner periphery thereof; a linear moving barrel guided along the optical axis without rotating about the optical axis; a unit secured inside the linear moving barrel; and a plurality of follower pins securing the unit to the linear moving barrel, the plurality of follower pins each projecting outwardly from an outer periphery of the linear moving barrel to engage with the plurality of guide grooves, respectively, so that the linear moving barrel is moved along the optical axis relative to the rotational barrel when the rotational barrel is driven to rotate. With this structure, the follower pins are used not only for being guided along the guide grooves but also for fixing the unit to the linear moving barrel. This contributes to decreasing the number of components of the lens barrel and thus realizing to make the lens barrel small and compact.

Preferably, the linear moving barrel is provided with a plurality of outer holes and the unit is provided with a corresponding plurality of inner holes, each of the plurality of outer holes being aligned in a radial direction with a corresponding one of the corresponding plurality of inner holes, wherein each of the plurality of follower pins engages with one of the plurality of outer holes and a corresponding one of the corresponding plurality of inner holes, with an outer end of the each of the plurality of follower pins projecting outwardly from the outer periphery of the linear moving barrel to engage with a corresponding one of the plurality of guide grooves.

Preferably, the outer end of the each of the plurality of follower pins is tapered in a direction away from the optical axis.

The unit may be comprised of a plurality of components, the plurality of inner holes being formed on one of the plurality of components.

Preferably, the one of the plurality of components includes an annular member and a plurality of leg portions formed integral with the annular member and extending in a direction of the optical axis, the corresponding plurality of inner holes being respectively formed on the plurality of leg portions.

Preferably, the annular member supports shutter blades.

Preferably, the unit includes an annular member and a plurality of leg portions formed integral with the annular member and extending in a direction of the optical axis, the corresponding plurality of inner holes being respectively formed on the plurality of leg portions.

Preferably, the lens barrel further includes a linear guide member for guiding the unit along the optical axis without rotating about the optical axis, the linear guide member slidably engaging with the plurality of leg portions along the optical axis.

Preferably, the lens barrel further includes a photographic optical system having a plurality of lens groups, and a lens supporting barrel which supports a frontmost lens group of the plurality of lens groups therein, the linear moving barrel and the unit supporting the lens supporting barrel.

According to another aspect of the present invention, there is provided a lens barrel including: a rotational barrel driven to rotate about an optical axis of the lens barrel, the rotational barrel having a plurality of guide grooves formed on an inner periphery thereof; a linear moving barrel guided along the optical axis without rotating about the optical axis, the linear moving barrel being provided with a plurality of followers respectively engaging with the plurality of guide grooves, so that the linear moving barrel is moved along the optical axis relative to the rotational barrel when the rotational barrel is driven to rotate; and a unit secured to the linear moving barrel by a plurality of fixing members respectively formed integral with the plurality of followers.

An example of the present invention will be described below in detail with reference to the accompanying drawings in which similar elements are indicated by similar reference numerals, and wherein: Figure 1 is a sectional view of an upper part of a zoom lens barrel in a housed state; Figure 2 is an enlarged sectional view of a part of the zoom lens barrel; Figure 3 is an enlarged exploded perspective view of a part of the zoom lens barrel; Figure 4 is a schematic perspective view illustrating a state where an AF/AE shutter unit of the zoom lens barrel is mounted to a first moving barrel; Figure 5 is an enlarged schematic perspective view showing a part of the zoom lens barrel; Figure 6 is a schematic perspective view showing the part of the zoom lens barrel shown in Figure 5 in an engaged state; Figure 7 is an exploded perspective view illustrating main parts of the AF/AE shutter unit of the zoom lens barrel shown in Figure 3,4,5 or 6; Figure 8 is an enlarged schematic perspective view of a third moving barrel of the zoom lens barrel; Figure 9 is an enlarged perspective view of a linear guide barrel of the zoom lens barrel; Figure 10 is a front elevational view of a fixed lens barrel block of the zoom lens barrel; Figure 11 is a sectional view of an upper part of the zoom lens barrel in a maximum extended state; Figure 12 is a sectional view of an upper part of the zoom lens barrel, illustrating main elements in the housed state; Figure 13 is a sectional view of the upper part of the zoom lens barrel shown in Figure 12 in the maximum extended state; Figure 14 is an exploded perspective view of the overall structure of the zoom lens barrel; Figure 15 is a block diagram of a controlling system for controlling an operation of the zoom lens barrel; Figure 16 is a sectional view of an upper part of a lens supporting barrel which supports a front lens group therein, and a lens fixing ring which is to be screw-engaged with the lens supporting barrel; Figure 17 is an enlarged perspective view of the lens supporting barrel shown in Figure 16; and Figure 18 is an enlarged sectional view of a part of the lens fixing ring shown in Figure 16.

Figure 15 is a schematic representation of various elements which comprise a preferred embodiment of a zoom lens camera to which the present invention is applied. A concept of the present zoom lens camera will now be described with reference to Figure 15.

The zoom lens camera is provided with a zoom lens barrel (zoom lens) 10 of a three-stage delivery type (telescoping type) having three moving barrels, namely a first moving barrel (linear moving barrel) 20, a second moving barrel (rotational barrel) 19 and a third moving barrel 16, which are concentrically arranged in this order from an optical axis 0. In the zoom lens barrel 10 two lens groups are provided as a photographic optical system, namely a front lens group L1 having positive power and a rear lens group L2 having negative power.

In the camera body, a whole optical unit driving motor controller 60, a rear lens group driving motor controller 61, a zoom operating device 62, a focus operating device 63, an object distance measuring apparatus 64, a photometering apparatus 65, and an AE (i.e., automatic exposure) motor controller 66, are provided. Although the specific focusing system of the object distance measuring apparatus 64, which is used to provide information regarding the object-tocamera distance, does not form part of the present invention, one such suitable system is disclosed in commonly assigned U.K. Patent Application No. 22983312 filed on February 22, 1996 and published on 28 August 1996.

Although the focusing systems disclosed in U.K. Patent Application No.

2298331 are of the so-called "passive" type, other known autofocus systems (e.g., active range finding systems such as those based on infrared light and triangulation) may be used. Similarly, a photometering system as disclosed in the above-noted U.K. Patent Application No. 2298331 could be implemented as photometering apparatus 65.

The zoom operating device 62 can be provided in the form of, for example, a manually-operable zoom operating lever (not shown) provided on the camera body or a pair of zoom buttons, e.g., a "wide" zoom button and a tele zoom button, (not shown) provided on the camera body. When the zoom operating device 62 is operated, the whole optical unit driving motor controller 60 drives a whole optical unit driving motor 25 to move the front lens group L1 and the rear lens group L2, rearwardly or forwardly without regard to a focal length and a focal point thereof. In the following explanation, forward and rearward movements of the lens groups L1 and L2 by the whole optical unit driving motor controller 60 (the motor 25) are referred to as the movement toward "tele" and the movement toward "wide" respectively, since forward and rearward movements of the lens groups L1 and L2 occur when the zoom operating device 62 is operated to "tele" and "wide" positions.

The image magnification of the visual field of a zoom finder 67 provided in the camera body varies in sequence with the variation of the focal length through the operation of the zoom operating device 62. Therefore, the photographer can perceive the variation of the focal length by observing the variation of image magnification of the visual field of the finder. In addition, the focal length, set by the operation of the zoom operating device 62, may be perceived by a value indicated on an LCD (liquid crystal display) panel (not shown) or the like.

When the focus operating device 63 is operated, the whole optical unit driving motor controller 60 drives the whole optical unit driving motor 25. At the same time the rear lens group driving motor controller 61 drives a rear lens group driving motor 30. Due to the driving of the whole optical unit driving motor controller 60 and the rear lens group driving motor controller 61, the front and rear lens groups L1 and L2 are moved to respective positions corresponding to a set focal length and a detected object distance and thereby the zoom lens is focused on the subject.

Specifically, the focus operating device 63 is provided with a release button (not shown) provided on an upper wall of the camera body. A photometering switch and a release switch (both not shown) are synchronized with the release button. When the release button is half-depressed (half step), the focus operating device 63 causes the photometering switch to be turned ON, and the object distance measuring and photometering commands are respectively input to the object distance measuring apparatus 64 and the photometering apparatus 65.

When the release button is fully depressed (full step), the focus operating device 63 causes the release switch to be turned ON, and according to the result of object distance measuring demand and a set focal length, the whole optical unit driving motor 25 and the rear lens group driving motor 30 are driven, and the focusing operation, in which the front lens group L1 and the rear lens group L2 move to the focusing position, is executed. Further, an AE motor 29 of an AF/AE (i.e., autofocus/autoexposure) shutter unit (electrical unit) 21 (Figure 1) is driven via the AE motor controller 66 to actuate a shutter 27. During the shutter action, the AE motor controller 66 drives the AE motor 29 to open shutter blades 27a of the shutter 27 for a specified period of time according to the photometering information output from the photometering apparatus 65.

When the zoom operating device 62 is operated, the zoom operating device 62 drives the whole optical unit driving motor 25 to move the front and rear lens groups L1 and L2 together as a whole in the direction of the optical axis 0 (optical axis direction). Simultaneous with such a movement, the rear lens group driving motor 30 may also be driven via the rear lens group driving motor controller 61 to move the rear lens group L2 relative to the front lens group L1. However, this is not performed under the conventional concept of zooming in which the focal length is varied sequentially without moving the position of the focal point. When the zoom operating device 62 is operated, the following two modes are available, namely: 1. a mode to move the front lens group L1 and the rear lens group L2 in the optical axis direction without varying the distance therebetween by driving only the whole optical unit driving motor 25; and, 2. a mode to move the front lens group L1 and the rear lens group L2 in the optical axis direction while varying the distance therebetween by driving both the whole optical unit driving motor 25 and the rear lens group driving motor 30.

In mode 1, during a zooming operation an in-focus condition cannot be obtained at all times with respect to a subject located at a specific distance. However, this is not a problem in a lens-shutter type camera, since the image of the subject is not observed through the photographing optical system, but through the finder optical system that is provided separate from the photographing optical system, and it is sufficient to only be focused when the shutter is released. In mode 2, during a zooming operation, the front lens group L1 and the rear lens group L2 are moved without regard to whether the focal point moves, and when the shutter is released, the focusing operation (focus adjusting operation) is carried out by moving both the whole optical unit driving motor 25 and the rear lens group driving motor 30.

When the focus operating device 63 is operated in at least one part of the focal length range set by the zoom operating device 62, the whole optical unit driving motor 25 and the rear lens group driving motor 30 are driven to bring the subject into focus. The amount of movement of each lens group L1 or L2 by the whole optical unit driving motor 25 and the rear lens group driving motor 30 is determined not only using subject distance information provided from the object distance measuring apparatus 64, but also by using focal length information set by the zoom operating device 62. In such a manner, when the focus operating device 63 is operated, by moving both the whole optical unit driving motor 25 and the rear lens group driving motor 30, the position of the lens groups L1, L2 can be flexibly controlled, as compared with lens movements controlled by cam.

The zoom lens camera of this embodiment can also be controlled in a different manner such that, during an operation of the zoom operating device 62, only the magnification of the zoom finder 67 and the focal length information are varied without driving either the whole optical unit driving motor 25 or the rear lens group driving motor 30. When the focus operating device 63 is operated, both the whole optical unit driving motor 25 and the rear lens group driving motor 30 are moved simultaneously according to the focal length information and the subject distance information obtained by the object distance measuring apparatus 64 to move the front lens group L1 and the rear lens group L2 to respective positions determined according to the focal length and the subject distance information.

An embodiment of the zoom lens barrel according to the above concept will now be described with reference to mainly Figures 1 and 14.

The overall structure of the zoom lens barrel 10 will firstly be described.

The zoom lens barrel 10 is provided with the first moving barrel 20, the second moving barrel 19, the third moving barrel 16, and a fixed lens barrel block 12. The third moving barrel 16 is engaged with a cylindrical portion 12p of the fixed lens barrel block 12, and moves in the optical axis direction upon being rotated. The third moving barrel 16 is provided on an inner periphery thereof with a linear guide barrel 17, which is restricted in rotation.

The linear guide barrel 17 and the third moving barrel 16 move together as a whole in the optical axis direction, with the third moving barrel 16 rotating relative to the linear guide barrel 17. The first moving barrel 20 moves in the optical axis direction with rotation thereof being restricted. The second moving barrel 19 moves in the optical axis direction, while rotating relative to the linear guide barrel 17 and the first moving barrel 20. The whole optical unit driving motor 25 is secured to the fixed lens barrel block 12. A shutter mounting stage 40 is secured to the first moving barrel 20. The AE motor 29 and the rear lens group driving motor 30 are mounted on the shutter mounting stage 40. The front lens group L1 and the rear lens group L2 are respectively supported by a lens supporting barrel (lens supporting annular member) 34 and a lens supporting barrel 50.

An O-ring 70, made of a rubber or the like, is positioned between an outer peripheral circumferential surface of the lens supporting barrel 34, in the vicinity of the front end thereof, and an inner peripheral circumferential surface of an inner flange portion 20b formed integral with the first moving barrel 20 in the vicinity of the front end thereof, as shown in Figure 1.

The O-ring 70 prevents water from penetrating the zoom lens barrel 10 at the front end thereof between the first moving barrel 20 and the lens supporting barrel 34.

As shown in Figure 16, the front lens group L1 consists of five lenses, namely, a first lens (frontmost lens) Lla, a second lens Llb, a third lens Llc, a fourth lens Lld and a fifth lens Lle in this order from an object side to an image side, i.e., from the left hand side to the right hand side as viewed in Figure 16.

A front positioning ring 36 for determining a distance between the second lens Llb and the third lens Llc is positioned and held between the second lens Llb and the third lens Llc. An outer peripheral surface of the positioning ring 36 is fitted on an inner peripheral surface of the lens supporting barrel 34. Likewise, a rear positioning ring 37 for determining a distance between the third lens Llc and the fourth lens Lld is positioned and held between the third lens Llc and the fourth lens L1d. An outer peripheral surface of the positioning ring 37 is fitted on an inner peripheral surface of the lens supporting barrel 34. The rear surface of the fourth lens Lld and the front surface of the fifth lens Lle are cemented to each other, so that the fourth and fifth lenses Lld, Lle are formed as a cemented or composite lens. A front circumferential edge Llf of the second lens Llb along the circumferential edge thereof contacts the rear surface of the first lens Lla. A rear circumferential edge Llg of the fifth lens Lle along the circumferential edge thereof contacts an inwardly-projecting flange 34b formed integral with the rear end of the lens supporting barrel 34.

A female thread 34a is formed on an inner periphery of a front part of the lens supporting barrel 34, as shown in Figure 16 or 17. A lens fixing ring 72, for fixing the first lens Lla to the lens supporting barrel 34, engages with the lens supporting barrel 34. With this arrangement, a male thread 72a formed on the outer peripheral surface of the lens fixing ring 72 meshes with the female thread 34a.

A circular abutting surface 72b is formed on the lens fixing ring 72 on an inner peripheral surface thereof. The circular abutting surface 72b comes into contact with a circumferential portion fp of the front surface of the first lens Lla in a state when the lens fixing ring 72 is properly screw-engaged with the lens supporting barrel 34. The circular abutting surface 72b is formed to be substantially parallel to the circumferential portion fp so that the circular abutting surface 72b and the circumferential portion fp may be brought tightly into contact with each other when the lens fixing ring 72 is properly screw-engaged with the lens supporting barrel 34.

A supporting-ring portion 34c is formed integral with the lens supporting barrel 34. The supporting ring portion 34c is located inwardly from the female thread 34a in a radial direction of the lens supporting barrel 34. The inner peripheral surface of the supporting ring portion 34c, which extends in the optical axis direction, comes into contact with an outer circumferential edge or surface op of the first lens Lla. An annular positioning surface 34d, extending substantially normal to the optical axis 0, is formed on the lens supporting barrel 34 immediately behind the supporting ring portion 34c. The circumferential edge of the rear surface of the first lens Lla comes into contact with the positioning surface 34d. With this structure, the first lens Lla is immovably held between the circular abutting surface 72b and the positioning surface 34d in the optical axis direction, and the first lens Lla is immovably held by the supporting ring portion 34c in a radial direction normal to the optical axis 0.

As shown in Figure 18, a coating 72e is coated on the circular abutting surface 72b. The coating 72e is a waterproof coating made of a synthetic resin. In the present embodiment, Fantas Coat SF-6 (trademark of a coating produced by the Japanese Company " Origin Denki Kabushiki Kaisha")l is used as the coating 72e. The front surface of the first lens Lla is formed very smooth, whereas the circular abutting surface 72b of the lens fixing ring 72 is not formed as smoothly (i.e., has a rough finish) as the front surface of the first lens Lla. This is because the first lens Lla is more minutely and accurately formed than the lens fixing ring 72 since the first lens Lla is a precision optical element. Due to this fact, were it not for the coating 72e on the circular abutting surface 72b, a substantial gap would be formed between the circular abutting surface 72b and the circumferential portion fp even if the circular abutting surface 72b properly and tightly in contact with the circumferential portion fp by properly screw-engaging the lens fixing ring 72 with the female thread 34a. As a result, water or moisture would be able to penetrate into the lens supporting barrel 34 through the substantial gap. However, in the present embodiment, the coating 72e is applied to the circular abutting surface 72b so as to make the surface thereof a smooth surface which does not cause to form such a substantial gap between the circular abutting surface 72b and the circumferential portion fp when the circular abutting surface 72b properly contacts the circumferential portion fp. Accordingly, the coating 72e, positioned and held between the circular abutting surface 72b and the circumferential portion fp, effectively prevents water or moisture from penetrating the lens supporting barrel 34 between the circular abutting surface 72b and the circumferential portion fp under the condition that the circular abutting surface 72b is properly and tightly in contact with the circumferential portion fp by properly screw-engaging the lens fixing ring 72 with the female thread 34a.

A circular surface 72c is formed on the lens fixing ring 72. The circular surface 72c is connected to the circular abutting surface 72b and is located immediately outward in a radial direction from the circular abutting surface 72b. A front part of the outer circumferential surface op of the first lens Lla (i.e., a circumferential edge of the first lens Lla) comes into contact with the circular surface 72c when the lens fixing ring 72 properly engages with the female thread 34a. Due to the circular surface 72c contacting the outer circumferential surface op, the watertight structure between the circular abutting surface 72b and the circumferential portion fp, that is realized by the coating 72e, is enhanced. That is, a highly efficient watertight connection between the first lens Lla and the lens fixing ring 72 is realized by providing both the coating 72e and the circular surface 72c with the lens fixing ring 72.

An annular recessed portion 34e is formed on the lens supporting barrel 34 between the female thread 34a and the supporting ring portion 34c. As shown in Figure 1, in a state where the lens fixing ring 72 is properly screwengaged with the female thread 34a, a rear end 72d of the lens fixing ring 72 is positioned in the annular recessed portion 34e with the rear end 72d not contacting the bottom (i.e., rearmost end) of the recessed portion 34e, namely, an annular space is formed in the annular recessed portion 34e between the rear end 72d and the bottom of the recessed portion 34e.

The fixed lens barrel block 12 is fixed in front of an aperture plate 14 fixed to the camera body. The aperture plate 14 is provided on a center thereof with a rectangularshaped aperture 14a which forms the limits of each frame exposed. The fixed lens barrel block 12 is provided, on an inner periphery of the cylindrical portion 12p, with a female helicoid 12a, and also a plurality of linear guide grooves 12b each extending parallel to the optical axis 0, i.e., extending in the optical axis direction. At the bottom of one of the linear guide grooves 12b, namely 12b', a code plate 13a, having a predetermined code pattern, is fixed. The code plate 13a extends in the optical axis direction and extends along substantially the whole of the length of the fixed lens barrel block 12. The code plate 13a is part of a flexible printed circuit board 13 positioned outside the fixed lens barrel block 12.

In the fixed lens barrel block 12, a gear housing 12c, which is recessed outwardly from an inner periphery of the cylindrical portion 12p of the fixed lens barrel block 12 in a radial direction while extending in the optical axis direction, is provided as shown in Figure 10 or 14. In the gear housing 12c, a driving pinion 15, extending in the optical axis direction, is rotatably held. Both ends of an axial shaft 7 of the driving pinion 15 are rotatively supported by a supporting hollow 4, provided in the fixed lens barrel block 12, and a supporting hollow 31a, provided on a gear supporting plate 31 fixed on the fixed lens barrel block 12 by set screws (not shown), respectively. Part of the teeth of the driving pinion 15 project inwardly from the inner periphery of the cylindrical portion 12p of the fixed lens barrel block 12 so that the driving pinion 15 meshes with an outer peripheral gear 16b of the third moving barrel 16, as shown in Figure 10.

On an inner periphery of the third moving barrel 16, a plurality of linear guide grooves 16c, each extending parallel to the optical axis 0, are formed. At an outer periphery of the rear end of the third moving barrel 16, a male helicoid 16a and the aforementioned outer peripheral gear 16b are provided as shown in Figure 8. The male helicoid 16a engages with the female helicoid 12a of the fixed lens barrel block 12. The outer peripheral gear 16b engages with the driving pinion 15. The driving pinion 15 has an axial length sufficient to be capable of engaging with the outer peripheral gear 16b throughout the entire range of movement of the third moving barrel 16 in the optical axis direction.

As shown in Figure 9, the linear guide barr plurality of engaging projections 17c each projecting away from the optical axis 0 in a radial direction. The linear guide barrel 17 is further provided, in front of the rear end flange 17d, with a retaining flange 17e. A circumferential groove 17g is formed between the rear end flange 17d and the retaining flange 17e. The retaining flange 17e has a radius smaller than the rear end flange 17d. The retaining flange 17e is provided with a plurality of cutout portions 17f. Each of the cutout portions 17f allows a corresponding engaging projection 16d to be inserted into the circumferential groove 17g, as shown in Figure 1.

The third moving barrel 16 is provided, on an inner periphery of the rear end thereof, with a plurality of engaging projections 16d. Each of the engaging projections 16d projects towards the optical axis 0 in a radial direction. By inserting the engaging projections 16d into the circumferential groove 17g, through the corresponding cutout portions 17f, the engaging projections 16d are positioned in the circumferential groove 17g between the flanges 17d and 17e (see Figure 1). By rotating the third moving barrel 16 relative to the linear guide barrel 17, the engaging projections 16d are engaged with the linear guide barrel 17.

On the rear end of the linear guide barrel 17, an aperture plate 23 having a rectangular-shaped aperture 23a approximately the same shape as the aperture 14a, is fixed.

The relative rotation of the linear guide barrel 17, with respect to the fixed lens barrel block 12, is restricted by the slidable engagement of the plurality of engaging projections 17c with the corresponding linear guide grooves 12b, formed parallel to the optical axis 0.

A contacting terminal 9 is fixed to one of the engaging projections 17c, namely 17c'. The contacting terminal 9 is in slidable contact with the code plate 13a, fixed to the bottom of the linear guide groove 12b, to generate signals corresponding to focal length information during zooming.

On the inner periphery of the linear guide barrel 17 a plurality of linear guide grooves 17a are formed, each extending parallel to the optical axis 0. A plurality of lead slots 17b are also formed on the linear guide barrel 17 as shown in Figure 9 or 14. The lead slots 17b are each formed oblique (inclined) to the optical axis 0.

The second moving barrel 19 engages with the inner periphery of the linear guide barrel 17. On the inner periphery of the second moving barrel 19, a plurality (three) of lead grooves (guide grooves) 19c are provided in a direction inclined oppositely to the lead slots 17b. A plurality of follower pins (three follower pins) 24 are provided on the first moving barrel 20 and respectively slidably engage with the plurality of lead grooves 19c.

Cam grooves or slots formed on a barrel or ring member are, in the usual sense, formed as non-linear grooves or slots, so that the speed of movement of the follower pins, which respectively engage with the cam grooves or slots when driven to move in the optical axis direction, varies even if the barrel or ring member provided with the cam grooves or slots is driven to rotate at a constant rotational speed.

The lead grooves l9c formed on the second moving barrel 19 are formed in this case as linear grooves so that the follower pins 24 are driven to move in the optical axis direction at a constant speed as the second moving barrel 19 is rotated at a constant rotational speed. However, each lead groove 19c is regarded as a particular type of cam groove for moving the corresponding follower pin 24 in the optical axis direction at a speed having no variation as the second moving barrel 19 is rotated at a constant rotational speed. Therefore, the lead grooves l9c may be considered to be cam grooves formed on the second moving barrel 19.

On the outer periphery of the rear end of the second moving barrel 19 a plurality of follower projections 19a are provided. Each of the follower projections 19a has a trapezoidal cross-sectional shape projecting away from the optical axis 0 in a radial direction. Follower pins 18 are positioned in the follower projections 19a. Each follower pin 18 consists of a ring member 18a, and a center fixing screw 18b which supports the ring member 18a on the corresponding follower projection 19a. The follower projections 19a are in slidable engagement with the lead slots 17b of the linear guide barrel 17, and the follower pins 18 are in slidable engagement with the linear guide grooves 16c of the third moving barrel 16. With such an arrangement, when the third moving barrel 16 rotates, the second moving barrel 19 moves linearly in the optical axis direction, while rotating.

On the inner periphery of the second moving barrel 19, the first moving barrel 20 is engaged. The first moving barrel 20 is provided on an outer periphery of the rear thereof with the aforementioned plurality of follower pins 24 each engaging with the corresponding inner lead groove 19c, and at the same time the first moving barrel 20 is guided linearly by a linear guide member 22. The first moving barrel 20 is provided at the front end thereof with a decorative plate 41 secured thereto.

As shown in Figures 5 and 6, the linear guide member 22 is provided with an annular member 22a, a pair of guide legs 22b and a plurality of engaging projections 28. The pair of guide legs 22b project from the annular member 22a in the optical axis direction. The plurality of engaging projections 28 each project from the annular member 22a away from the optical axis 0 in a radial direction. The engaging projections 28 slidably engage with the linear guide grooves 17a. The guide legs 22b are respectively inserted into linear guides 40c between the inner peripheral surface of the first moving barrel 20 and the AF/AE shutter unit 21.

The annular member 22a of the linear guide member 22 is connected to the rear of the second moving barrel 19, such that the linear guide member 22 and the second moving barrel 19 are capable of moving along the optical axis O as a whole, and in addition are capable of relatively rotating around the optical axis 0. The linear guide member 22 is further provided on the outer periphery of the rear end thereof with a rear end flange 22d. The linear guide member 22 is further provided, in front of the rear end flange 22d, with a retaining flange 22c. A circumferential groove 22f is formed between the rear end flange 22d and the retaining flange 22c. The retaining flange 22c has a radius smaller than the rear end flange 22d. The retaining flange 22c is provided with a plurality of cutout portions 22e, as shown in Figure 5 or 6, each allowing a corresponding engaging projection 19b to be inserted into the circumferential groove 22f, as shown in Figure 1.

The second moving barrel 19 is provided on an inner periphery of the rear end thereof with a plurality of engaging projections 19b, each projecting towards the optical axis O in a radial direction. By inserting the engaging projections 19b into the circumferential groove 22f through the corresponding cutout portions 22e, the engaging projections 19b are positioned in the circumferential groove 22f between the flanges 22c and 22d. By rotating the second moving barrel 19 relative to the linear guide member 22, the engaging projections 19b are engaged with the linear guide member 22. With the above structure, when the second moving barrel 19 rotates in the forward or reverse rotational direction, the first moving barrel 20 moves linearly, forwardly or rearwardly along the optical axis 0, but is restricted from rotating.

At the front of the first moving barrel 20, a barrier apparatus 35 having barrier blades 48a and 48b is mounted.

On an inner peripheral face of the first moving barrel 20 the AF/AE shutter unit 21 having the shutter 27, consisting of three shutter blades 27a, is engaged and fixed, as shown in Figure 12.

As illustrated in Figures 7 and 14, the AF/AE shutter unit 21 is provided with the shutter mounting stage 40, a shutter blade supporting ring 46 fixed on the rear of the shutter mounting stage 40 so as to be located inside the shutter mounting stage 40, and the lens supporting barrel 50 supported in a state of being capable of movement relative to the shutter mounting stage 40. On the shutter mounting stage 40, the lens supporting barrel 34, the AE motor 29, and the rear lens group driving motor 30, are supported.

The shutter mounting stage 40 is provided with an annular member 40f having a circular aperture 40d. The shutter mounting stage 40 is also provided with three legs 40b which project rearward from the annular member 40f. Three slits are defined between the three legs 40b. Two of the slits comprise the aforementioned linear guides 40c, which slidably engage with the respective pair of guide legs 22b of the linear guide member 22 so as to guide the movement of the linear guide member 22.

Specifically, each guide leg 22b is provided with two linear surfaces (first guide surfaces) 22g extending parallel to each other, and each linear guide 40c has two linear guide surfaces (second guide surfaces) 40e with which the corresponding two linear surfaces 22g respectively come in sliding contact. The two linear guide surfaces 40e of each linear guide 40c are formed parallel to each other on opposing edges of the two adjacent legs 40b, as shown in Figure 6. Accordingly, the width of each guide leg 22b is substantially the same as that of the corresponding linear guide 40c (i.e., the width between the two adjacent linear guide surfaces 40e). Strictly speaking, the width of each guide leg 22b is slightly narrower than that of the corresponding linear guide 40c so that each guide leg 22b can smoothly slide along the corresponding linear guide 40c.

The shutter mounting stage 40 supports an AE gear train 45, which transmits a rotation of the AE motor 29 to the shutter 27, a lens driving gear train 42, which transmits rotation of the rear lens group driving motor 30 to a screw shaft 43, photointerrupters 56 and 57, connected to a flexible printed circuit board 6, and rotating disks 58 and 59, having a plurality of radially formed slits provided in the circumferential direction. An encoder for detecting whether the rear lens group driving motor 30 is rotating and for detecting an amount of rotation of the rear lens group driving motor 30 consists of the photointerrupter 57 and the rotating disk 59. An AE motor encoder for detecting whether the AE motor 29 is rotating and for detecting an amount of rotation of the AE motor 29 consists of the photointerrupter 56 and the rotating disk 58.

The shutter 27, a supporting member 47 which pivotally supports the three shutter blades 27a of the shutter 27, and a circular driving member 49, which gives rotative power to the shutter blades 27a, are positioned between the shutter mounting stage 40 and the shutter blade supporting ring 46, secured to the shutter mounting stage 40. The circular driving member 49 is provided with three operating projections 49a at even angular intervals, which respectively engage with each of the three shutter blades 27a. As shown in Figure 7, the shutter blade supporting ring 46 is provided at a front end thereof with a circular aperture 46a and with three supporting holes 46b positioned at even angular intervals around the circular aperture 46a.

Two deflection restricting surfaces 46c are formed on the outer periphery of the shutter blade supporting ring 46.

Each deflection restricting surface 46c is exposed outwardly from the corresponding linear guide 40c and slidably supports the inner peripheral face of the corresponding guide leg 22b.

The supporting member 47, positioned in front of the shutter blade supporting ring 46, is provided with a circular aperture 47a, aligned with the circular aperture 46a of the shutter blade supporting ring 46, and with three pivotal shafts 47b (only one of which is illustrated in Figure 7) at respective positions opposite the three supporting holes 46b. Each shutter blade 27a is provided at one end thereof with a hole 27b into which the corresponding pivotal shaft 47b is inserted, so that each shutter blade 27a is rotatable about the corresponding pivotal shaft 47b.

The major part of each shutter blade 27a, that extends normal to the optical axis 0 from the pivoted end, is formed as a light interceptive portion. All three light interceptive portions of the shutter blades 27a together prevent ambient light, which enters the front lens group L1, from entering the circular apertures 46a and 47a when the shutter blades 27a are closed. Each shutter blade 27a is further provided, between the hole 27b and the light interceptive portion thereof, with a slot 27c, through which the corresponding operating projection 49a is inserted. The supporting member 47 is fixed to the shutter blade supporting ring 46 in such a manner that each shaft 47b, which supports the corresponding shutter blade 27a, is engaged with the corresponding supporting hole 46b of the shutter blade supporting ring 46.

A gear portion 49b is formed on a part of the outer periphery of the circular driving member 49. The gear portion 49b meshes with one of the plurality of gears in the gear train 45 to receive the rotation from the gear train 45. The supporting member 47 is provided, at respective positions close to the three pivotal shafts 47b, with three arc grooves 47c each arched along a circumferential direction. The three operating projections 49a of the circular driving ring 49 engage with the slots 27c of the respective shutter blades 27a through the respective arc grooves 47c. The shutter blade supporting ring 46 is inserted from the rear of the shutter mounting stage 40, to support the circular driving ring 49, the supporting member 47 and the shutter 27, and is fixed on the shutter mounting stage 40 by set screws 90 respectively inserted through holes 46x provided on the shutter blade supporting ring 46.

Behind the shutter blade supporting ring 46, the lens supporting barrel 50, supported to be able to move relative to the shutter mounting stage 40 via guide shafts 51 and 52, is positioned. The shutter mounting stage 40 and the lens supporting barrel 50 are biased in opposite directions away from each other by a coil spring 3 fitted on the guide shaft 51, and therefore play between the shutter mounting stage 40 and the lens supporting barrel 50 is reduced. In addition, a driving gear 42a, provided as one of the gears in the gear train 42, is provided with a female thread hole (not shown) at the axial center thereof and is restricted to move in the axial direction. The screw shaft 43, one end of which is fixed to the lens supporting barrel 50, engages with the female thread hole. Accordingly, the driving gear 42a and the screw shaft 43 together constitute a feed screw mechanism. In such a manner, when the driving gear 42a rotates clockwise or anti-clockwise due to driving by the rear lens group driving motor 30, the screw shaft 43 respectively moves forwardly or rearwardly with respect to the driving gear 42a, and therefore the lens supporting barrel 50, which supports the rear lens group L2, moves relative to the front lens group L1.

A holding member 53 is fixed at the front of the shutter mounting stage 40. The holding member 53 holds the motors 29 and 30 between the holding member 53 and the shutter mounting stage 40. The holding member 53 has a metal holding plate 55 fixed at the front thereof by set screws 99. The motors 29, 30 and the photointerrupters 56, 57 are connected to the flexible printed circuit board 6.

One end of the flexible printed circuit board 6 is fixed to the shutter mounting stage 40.

The structure for fixing the AF/AE shutter unit 21 to the inner peripheral surface of the first moving barrel 20 will be hereinafter discussed.

The first moving barrel 20 is provided at the rear end thereof with three holes (outer holes) 20a formed at even angular intervals in a circumferential direction of the first moving barrel 20. Only one of the three holes 20a is shown in Figure 2 or 3. The AF/AE shutter unit 21 (that is fixed to the first moving barrel 20), is provided, on one of the components of the AF/AE shutter unit 21, i.e., the shutter mounting stage 40, with three fixing holes (inner holes) 40a formed at even angular intervals on the outer periphery of the shutter mounting stage 40. Only one of the three fixing holes 40a is shown in each of Figures 2 through 7. Each of the follower pins 24 consists of an engaging head 24a and a fixing shaft 24b which are formed integral with each other. Each engaging head 24a has a diameter larger than the corresponding fixing hole 40a and is shaped to taper outwardly in a radial direction, i.e., each engaging head 24a is tapered in a radial direction away from the optical axis 0. The diameter of each fixing shaft 24b is slightly narrower than either the corresponding hole 20a or the corresponding fixing hole 40a. The AF/AE shutter unit 21 is fixed to the inner peripheral surface of the first moving barrel 20 such that the fixing shafts 24b are respectively inserted in the holes 20a and fixed in the fixing holes 40a, with the holes 20a and the fixing holes 40a being aligned. Namely, the shutter mounting stage 40 is fixed to the inner peripheral surface of the first moving barrel 20 through the follower pins 24. Therefore, the follower pins 24, which engage with the inner lead grooves 19c, also serve as a device for fixing the AF/AE shutter unit 21 to the first moving barrel 20. With this arrangement the AF/AE shutter unit 21 is secured to the first moving barrel 20 as shown in Figure 4. In Figure 4 the first moving barrel 20 is indicated by phantom lines.

The fixing shafts 24b of the follower pins 24 may be fixed by an adhesive, or the fixing shafts 24b may be formed as screws to be screwed into the fixing holes 40a.

As can be appreciated from the foregoing, the follower pins 24 are used not only for being guided along the lead grooves l9c but also for fixing the AF/AE shutter unit 21 to the first moving barrel 20. This contributes to decreasing the number of components of the zoom lens barrel 10 and thus realizing to make the zoom lens barrel 10 small and compact.

Furthermore, since the AF/AE shutter unit 21 is fixed to the first moving barrel 20 by the follower pins 24, which function to determine the position of the first moving barrel 20 relative to the second moving barrel 19 through the lead grooves 19c, the AF/AE shutter unit 21 can be very accurately positioned relative to the second moving barrel 19.

After the first, second and third moving barrels 20, 19 and 16, and the AF/AE shutter unit 21 and the like are assembled, the aperture plate 23 is fixed to the rear of the linear guide barrel 17, and an annular retaining member 33 is fixed at the front of the fixed lens barrel block 12.

In the above-described embodiment of the zoom lens barrel 10, although the zoom lens optical system consists of two movable lens groups, namely the front lens group L1 and the rear lens group L2, it should be understood that the present invention is not limited to the present embodiment disclosed above, but the present invention may also be applied to another type of zoom lens optical system including one or more fixed lens group.

In addition, in the above embodiment, the rear lens group L1 is provided as a component of the AF/AE shutter unit 21, and the AE motor 29 and the rear lens group driving motor 30 are mounted to the AF/AE shutter unit 21. With such a structure, the structure for supporting the front and rear lens groups L1 and L2 and the structure for driving the rear lens group L2 are both simplified. Instead of adopting such a structure, the present zoom lens may also be realized in such a manner by making the rear lens group L2 a member separate from the AF/AE shutter unit 21, which is provided with the shutter mounting stage 40, the circular driving member 49, the supporting member 47, the shutter blades 27, the shutter blade supporting ring 46 and the like, and that the rear lens group L2 is supported by any supporting member other than the AF/AE shutter unit 21.

In the zoom lens camera of the present embodiment, the operation by rotation of the whole optical unit driving motor 25 and the rear lens group driving motor 30 will now be described with reference to Figures 1, 11, 12 and 13.

As shown in Figure 1 or 12, when the zoom lens barrel 10 is at the most retracted (withdrawn) position, i.e., the lens-housed condition, when the power switch is turned ON, the whole optical unit driving motor 25 is driven to rotate its drive shaft in the forward rotational direction by a small amount. This rotation of the motor 25 is transmitted to the driving pinion 15 through a gear train 26, which is supported by a supporting member 32 formed integral with the fixed lens barrel block 12, to thereby rotate the third moving barrel 16 in one predetermined rotational direction to advance forwardly along the optical axis 0. Therefore, the second moving barrel 19 and the first moving barrel 20 are each advanced by a small amount in the optical axis direction, along with the third moving barrel 16.

Consequently, the camera is in a state capable of photographing, with the zoom lens positioned at the widest position, i.e., the wide end. At this stage, due to the fact that the amount of movement of the linear guide barrel 17, with respect to the fixed lens barrel block 12, is detected through the relative slide between the code plate 13a and the contacting terminal 9, the focal length of the zoom lens barrel 10, i.e., the front and rear lens groups L1 and L2, is detected.

In the photographable state as above described, when the aforementioned zoom operating lever is manually moved towards a "tele* side, or the "tele" zoom button is manually depressed to be turned ON, the whole optical unit driving motor 25 is driven to rotate its drive shaft in the forward rotational direction through the whole optical unit driving motor controller 60 so that the third moving barrel 16 rotates in the rotational direction to advance along the optical axis 0 via the driving pinion 15 and the outer peripheral gear 16b. Therefore, the third moving barrel 16 is advanced from the fixed lens barrel block 12 according to the relationship between the female helicoid 12a and the male helicoid 16a. At the same time, the linear guide barrel 17 moves forwardly in the optical axis direction together with the third moving barrel 16, without relative rotation to the fixed lens barrel block 12, according to the relationship between the engaging projections 17c and the linear guide grooves 12b. At this time, the simultaneous engagement of the follower pins 18 with the respective lead slots 17b and linear guide grooves 16c causes the second moving barrel 19 to move forwardly relative to the third moving barrel 16 in the optical axis direction, while rotating together with the third moving barrel 16 in the same rotational direction relative to the fixed lens barrel block 12. The first moving barrel 20 moves forwardly from the second moving barrel 19 in the optical axis direction, together with the AF/AE shutter unit 21, without relative rotation to the fixed lens barrel block 12, due to the above-noted structures in which the first moving barrel 20 is guided linearly by the linear guide member 22 and in which the follower pins 24 are guided by the lead grooves l9c. During such movements, according to the fact that the moving position of the linear guide barrel 17 with respect to the fixed lens barrel block 12 is detected through the relative slide between the code plate 13a and the contacting terminal 9, the focal length set by the zoom operation device 62 is detected.

Conversely, when the zoom operating lever is manually moved towards a "wide" side, or the "wide zoom button is manually depressed to be turned ON, the whole optical unit driving motor 25 is driven to rotate its drive shaft in the reverse rotational direction through the whole optical unit driving motor controller 60 so that the third moving barrel 16 rotates in the rotational direction to retract into the fixed lens barrel block 12 together with the linear guide barrel 17. At the same time, the second moving barrel 19 is retracted into the third moving barrel 16, while rotating in the same direction as that of the third moving barrel 16, and the first moving barrel 20 is retracted into the rotating second moving barrel 19 together with the AF/AE shutter unit 21. During the above retraction driving, like the case of advancing driving as above described, the rear lens group driving motor 30 is not driven.

While the zoom lens barrel 10 is driven during the zooming operation, since the rear lens group driving motor 30 is not driven, the front lens group L1 and the rear lens group L2 move as a whole, maintaining a constant distance between each other, as shown in Figure 11 or 13. The focal length input via the zoom code plate 13a and the contacting terminal 9 is indicated on an LCD panel (not shown) provided on the camera body.

At any focal length set by the zoom operating device 62, when the release button is depressed by a half-step, the object distance measuring apparatus 64 is actuated to measure a current subject distance. At the same time the photometering apparatus 65 is actuated to measure a current subject brightness. Thereafter, when the release button is fully depressed, the whole optical unit driving motor 25 and the rear lens group driving motor 30 are each driven by respective amounts dictated according to the focal length information set in advance and the subject distance information obtained from the object distance measuring apparatus 64 so that the front and rear lens groups L1 and L2 are respectively moved to specified positions to obtain a specified focal length to thereby bring the subject into focus. Immediately after the subject is brought into focus, via the AE motor controller 66, the AE motor 29 is driven to rotate the circular driving member 49 by an amount corresponding to the subject brightness information obtained from the photometering apparatus 65 so that the shutter 27 is driven to open the shutter blades 27a by a specified amount which satisfies the required exposure. Immediately after such a shutter release operation, in which the three shutter blades 27a are opened and subsequently closed, is completed, the whole optical unit driving motor 25 and the rear lens group driving motor 30 are both driven to move the front lens group L1 and the rear lens group L2 to the respective initial positions at which they were at prior to a shutter release.

In the present embodiment of the zoom lens barrel 10, "Fantas Coat SF-6" is used as the coating 72e. However, a different type of coating may be used as the coating 72e as long as it is waterproof and makes the circular abutting surface 72b a smooth surface to form substantially no gap between the circular abutting surface 72b and the circumferential portion fp.

Obvious changes may be made in the specific embodiments of the present invention described herein, such modifications being within the scope of the invention claimed. It is indicated that all matter contained herein is illustrative and does not limit the scope of the present invention.

Claims

CLAIMS:

1. A lens barrel comprising: a rotation barrel drivable to rotate about an optical axis of said lens barrel, said rotational barrel having a plurality of guide grooves formed on an inner periphery thereof; a linear movement barrel guidable along said optical axis without rotating about said optical axis; a unit secured inside said linear movement barrel; and a plurality of follower pins securing said unit to said linear movement barrel, said plurality of follower pins each projecting outwardly from an outer periphery of said linear movement barrel to engage with said plurality of guide grooves, respectively, so that said linear movement barrel is moved along said optical axis relative to said rotational barrel when said rotational barrel is driven to rotate.

2. A lens barrel according to claim 1, wherein said linear movement barrel is provided with a plurality of through holes and said unit is provided with a corresponding plurality of follower holes, each of said plurality of through holes being aligned in a radial direction with a corresponding one of said corresponding plurality of follower holes, wherein each of said plurality of follower pins engages with one of said plurality of through holes and a corresponding one of said corresponding plurality of follower holes, with an outer end of said each of said plurality of follower pins projecting outwardly from said outer periphery of said linear movement barrel to engage with a corresponding one of said plurality of guide grooves.

3. A lens barrel according to claim 1 or 2, wherein said outer end of said each of said plurality of follower pins is tapered in a direction away from said optical axis.

4. A lens barrel according to claim 2 or 3, wherein said unit is comprised of a plurality of components, said plurality of follower holes being formed on one of said plurality of components.

5. A lens barrel according to claim 4, wherein said one of said plurality of components comprises an annular member and a plurality of leg portions formed integrally with said annular member and extending in a direction of said optical axis, said corresponding plurality of follower holes being respectively formed on said plurality of leg portions.

6. A lens barrel according to claim 5, wherein said annular member supports shutter blades.

7. A lens barrel according to claim 2, wherein said unit comprises an annular member and a plurality of leg portions formed integrally with said annular member and extending in a direction of said optical axis, said corresponding plurality of follower holes being respectively formed on said plurality of leg portions.

8. A lens barrel according to claim 5, further comprising a linear guide member for guiding said unit along said optical axis without rotating about said optical axis, said linear guide member slidably engaging with said plurality of leg portions along said optical axis.

9. A lens barrel according to any preceding claim, further comprising a photographic optical system having a plurality of lens groups, and a lens supporting barrel which supports a frontmost lens group of said plurality of lens groups therein, said linear movement barrel and said unit supporting said lens supporting barrel.

10. A lens barrel comprising: a rotational barrel drivable to rotate about an optical axis of said lens barrel, said rotational barrel having one or more guide grooves formed on an inner periphery thereof; a linear movement barrel guidable along said optical axis without rotating about said optical axis, said linear movement barrel being provided with one or more followers respectively engaging with said one or more guide grooves, so that said linear moving barrel is movable along said optical axis relative to said rotational barrel when said rotational barrel is driven to rotate; and a unit secured to said linear moving barrel by one or more fixing members respectively formed integrally with said one or more followers.

11. A lens barrel substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.