JP2001004902A - Lens guiding mechanism - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens guiding mechanism realizing the variable power and the focusing of an optical system by a single driving source and a driving mechanism without rotating a lens barrel by performing focusing in a state where a rear group lens frame is held on the guide shaft of a moving barrel. SOLUTION: This mechanism is equipped with the guide shaft 37 installed to face toward the optical axis O and constituted by forming plural grooves 38 at specified intervals along the optical axis O on its surface, the moving barrel 4 housing a front group lens 5 and moving along the shaft 37, the rear group lens frame 7 housing a rear group lens 8 and supported movably within the fixed range toward the optical axis O with respect to the barrel 4, and a pressing part 73 installed in the frame 7, elastically pressing the surface of the shaft 37 and holding the frame 7 at the position of the groove 38.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens guide mechanism used for an optical system of an optical device such as a camera.

[0002]

2. Description of the Related Art In order to perform zooming in an optical system of an optical apparatus such as a camera, a zooming mechanism and a focusing mechanism are required. If these mechanisms are independent mechanisms, a lens driving system consisting of a lens driving motor, a lens position detecting element, etc. is required for each mechanism,
Two drive systems must be provided. In this case, there has been a great hindrance to miniaturization and cost reduction of the optical device.

In view of such a problem, Japanese Patent Application Laid-Open No. H5-25-2
As described in Japanese Patent No. 49362, in a zoom photographing optical system including a front group lens and a rear group lens, a holding cylinder of a front group lens and a drive ring for moving the same along an optical axis are helicoidally coupled. The holding member of the rear group lens is hung on a cam groove provided on the inner periphery of the drive ring, the front group lens is moved together with the holding cylinder by rotating the drive ring, and the rear group lens is moved according to the cam groove. There has been proposed an optical device for moving the light.

The cam groove of this optical device has a flat area orthogonal to the optical axis and an oblique area not orthogonal to the optical axis. The rear lens group is moved using the oblique area of the cam groove during the focus switching operation, and the rear lens group is not moved using the flat area of the cam groove during the focusing operation. This optical apparatus is intended to perform focus switching and focusing by a single drive source by using the cam groove as described above.

[0005]

However, in the above-described optical apparatus, it is necessary to rotate the drive ring about the optical axis during focusing. For this reason,
The technology of the optical device cannot be applied to a device that moves the rear lens group without rotating the drive ring or a device that does not have a drive ring.

Accordingly, the present invention has been made in view of such a technical problem, and it is possible to perform zooming and focusing of an optical system by a single driving source and a single driving mechanism without rotating a lens barrel. It is an object to provide a lens guide mechanism.

[0007]

In order to achieve the above object, a lens guide mechanism according to the present invention performs at least magnification and focusing by moving at least a front lens group and a rear lens group along an optical axis. A lens guide mechanism in a zoom lens optical system, which houses a front group lens and a guide shaft that is installed facing the direction of the optical axis and has a plurality of grooves formed at predetermined intervals on the surface along the optical axis. A front group lens housing that moves along the guide axis, a rear group lens housing that houses the rear group lens and is movably supported within a certain range in the direction of the optical axis with respect to the front group lens housing, And a holding unit that is installed in the group lens housing and elastically presses the surface of the guide shaft to hold the rear group lens housing at the position of the groove.

According to the present invention, when the front lens unit is moved along the guide axis, the rear lens unit is also moved. Then, by moving the front lens housing, the rear lens housing is moved to the position of the groove of the guide shaft, and is held on the guide shaft via the holding means, so that the magnification of the optical system can be changed. In this state, by moving the front group lens housing, the front group lens approaches or moves away from the rear group lens, so that focusing of the optical system can be performed. Therefore, stepwise zooming is possible with a single drive source.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Various embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings, the same elements are denoted by the same reference numerals, and the description is omitted. Also, the dimensional ratios in the drawings do not always match those described.

(First Embodiment) FIG. 1 shows a lens guide mechanism 1 according to the present embodiment. FIG. 2 is a vertical sectional view of the lens guide mechanism 1 when retracted as viewed from the front. The lens guide mechanism 1 according to the present embodiment is used for a photographing optical system of a camera 10 that photographs using a photographic film. The photographing optical system includes a front lens group 5 that moves along the optical axis O,
A rear group lens 8 is provided.

As shown in FIG. 1, the camera 10 is provided with a fixed cylinder 2. The fixed cylinder 2 is a cylinder having a rectangular cross section, for example, has a substantially rectangular cross section and has an internal space 21 therein. The fixed cylinder 2 is fixed to the main body of the camera 10 or formed integrally therewith.

A guide shaft storage chamber 22 is provided above the fixed cylinder 2.
Is provided. The guide shaft storage chamber 22 is formed by projecting the upper surface of the fixed cylinder 2 upward, and houses a guide shaft 23 and a feed screw 24 therein. The guide shaft 23 and the feed screw 24 each have a rod shape and are arranged in the optical axis direction. The feed screw 24 is rotatably provided, a thread is engraved on the outer periphery, and a helical gear 25 is attached to a rear end thereof. Helical gear 2
5, the torque of the motor 29 is transmitted through the helical gear 28a and the worm gear 28b. The transmission of this rotational force causes the helical gear 25 to rotate, and accordingly, the feed screw 24 to rotate. The transmission mechanism for transmitting the rotational force of the motor 29 to the feed screw 24 includes a helical gear 2
5. The mechanism is not limited to the mechanism using the helical gear 28a and the worm gear 28b, but may be a transmission mechanism using a spur gear.

A cam plate 26 is mounted on the upper surface of the internal space 21 of the fixed cylinder 2. A cam groove 27 is formed in the cam plate 26 at an angle to the optical axis O.

The camera 10 is provided with an intermediate cylinder 3 which can be extended and retracted with respect to the fixed cylinder 2. The intermediate cylinder 3 is a cylinder having a square cross section, and has, for example, a substantially square cross section. Further, the hollow cylinder 3 has an internal space 31 inside, and has a projection 34 formed at an upper portion of its rear end. The protrusion 34 has two insertion holes 32 and 33 formed in the optical axis direction. Insertion hole 32
Is a hole through which the guide shaft 23 of the fixed cylinder 2 is inserted,
By inserting the guide shaft 23 into the insertion hole 32,
The intermediate cylinder 3 is movable along the optical axis O.

On the other hand, the insertion hole 33 is a hole through which the feed screw 24 of the fixed cylinder 2 is inserted, and a thread groove for screwing with the thread of the feed screw 24 is formed in the inner periphery thereof. When the feed screw 24 inserted into the insertion hole 33 rotates, the intermediate cylinder 3 moves along the optical axis O according to the rotation.

The intermediate cylinder 3 is entirely or partially accommodated in the internal space 21 of the fixed cylinder 2 at the time of extension or retraction. However, in FIG. For convenience, the intermediate cylinder 3 is shown detached from the fixed cylinder 2.

A long hole 35 and a round hole 36 are formed in the upper part of the rear end of the intermediate cylinder 3 so as to pass through the inside and outside of the internal space 31. The long hole 35 is formed with its longitudinal direction oriented in a direction orthogonal to the optical axis O. In addition, the round hole 36 is a long hole 3
5 and are formed on the elongated hole 35 in the longitudinal direction.

A guide shaft 3 is provided in the internal space 31 of the intermediate cylinder 3.
7 is attached. The guide shaft 37 has a rod shape and is arranged in the optical axis direction. A plurality of grooves 38 are formed on the outer peripheral surface of the guide shaft 37. Groove 38
Are annular grooves formed along the circumferential direction of the guide shaft 37, and are formed at predetermined intervals in the axial direction of the guide shaft 37, for example, five grooves are formed. Also, the guide shaft 37
Is installed at the upper corner of the internal space 31 and below the guide shaft 23. A guide ridge 3 is provided on the inner wall of the intermediate cylinder 3 at a lower corner position diagonal to the guide shaft 37.
9 are formed.

The camera 10 is provided with a movable cylinder 4 which can be extended and retracted with respect to the intermediate cylinder 3. The moving cylinder 4 is a cylindrical body having a cross section in which one of the corners of a square is cut out, and having a notch 41 on an outer surface thereof. The front lens group 5 is accommodated in a front portion of the movable barrel 4. The rear end of the movable cylinder 4 is open.

Behind the notch 41 of the movable cylinder 4, a bearing 42 is formed. The bearing portion 42 supports the guide shaft 37 of the intermediate cylinder 3 and has an insertion hole 43 opened in the optical axis direction. The insertion hole 43 is provided in the guide shaft 3
7, and the guide shaft 37 is inserted into the insertion hole 43 so that the movable cylinder 4 can move along the optical axis O. Note that the moving cylinder 4 is entirely or partially accommodated in the internal space 31 of the intermediate cylinder 3 regardless of whether the moving cylinder 4 is extended or retracted.
In the figure, the moving cylinder 4 is shown detached from the intermediate cylinder 3 for convenience of explanation.

A guide shaft 4 is provided in the internal space 44 of the movable cylinder 4.
5 is attached. The guide shaft 45 has a rod shape and is arranged in the optical axis direction. An elongated hole 46 is formed in the upper part of the rear end of the movable cylinder 4 so as to pass through the inside and outside of the internal space 44. The long hole 46 has an optical axis O in the longitudinal direction.
It is formed in a direction orthogonal to. In addition, slot 4
A protrusion 47 is provided on the extension of the longitudinal direction of 6.

The camera 10 is provided with an X-shaped link mechanism 6 for extending and retracting the movable barrel 4. The link mechanism 6 is formed by crossing two links 61 and 62 in an X-shape, and supporting the crossed portion with a shaft pin 63. The front end 61 a of the link 61 is pivotally mounted on the projection 47 of the movable cylinder 4. A pin 64 passes through the front end 62a of the link 62 from above.
Further penetrates the elongated hole 46 of the movable cylinder 4. For this reason, the front end 62a of the link 62 is movable along the opening direction of the long hole 46, and movement in other directions is restricted.

The rear end 62b of the link 62 has a
As shown by the arrow B, the pin 65 penetrates from below. The pin 65 passes through the round hole 36 of the intermediate cylinder 3 as shown by an arrow B 'in FIG. For this reason, the rear end 62b of the link 62 is rotatably mounted at the opening position of the round hole 36. Further, a pin 66 passes through the rear end 61b of the link 61 from below as shown by an arrow A in FIG. The pin 66 passes through the long hole 35 of the intermediate cylinder 3 as shown by an arrow A 'in FIG. For this reason, the rear end 61b of the link 61 is movable along the opening direction of the elongated hole 35, and movement in other directions is restricted. Further, as shown by an arrow A ″ in FIG.
Has been inserted. Therefore, when the intermediate cylinder 3 moves along the optical axis O with respect to the fixed cylinder 2, the pin 66 moves along the cam groove 27, and the link 61 of the link mechanism 6,
The crossing angle of 62 changes. Due to the change in the crossing angle, the link mechanism 6 expands or contracts in the optical axis direction,
The moving cylinder 4 is moved relatively to the intermediate cylinder 3 so as to be extended or extended.

The camera 10 has a front group lens 5 of the movable barrel 4.
Is provided with a rear group lens frame 7 that moves behind the lens along the optical axis O. The rear lens group frame 7 is a frame housing the rear lens group 8, and has a bearing 71 at an outer edge thereof. The bearing portion 71 has a bearing hole 72 formed in parallel with the optical axis direction. The bearing hole 72 is a hole through which the guide shaft 45 of the moving cylinder 4 is inserted.
The guide shaft 45 is inserted through the rear lens frame 7.
Are movable along the optical axis O. The rear lens frame 7 is entirely or partially accommodated in either the internal space 44 or 31 of the movable barrel 4 or the intermediate barrel 3 at any time of extension or retraction.
FIG. 1 shows the rear lens group frame 7 detached from the movable barrel 4 or the intermediate barrel 3 for convenience of explanation.

As shown in FIG. 2, a pressing portion 73 is provided above the bearing 71 of the rear lens frame 7. The pressing portion 73 is a holding unit for elastically pressing the guide shaft 37 attached to the intermediate tube 3 to hold the rear lens group frame 7 at the position of the groove 38. It is configured to house a coil spring 75 and a pressing body 76. The pressing body 76 is a rod having a hemispherical head.
Is pressed against the outer peripheral surface of.

The pressing body 76 includes the guide shaft 37 and the guide shaft 4.
5, for example, on a line connecting the axis of the guide shaft 37 and the axis of the guide shaft 45. Therefore, the guide shaft 45 can receive the reaction force of the pressing body 76 pressing the guide shaft 37. Therefore, the pressing body 76
, The rotation force around the guide shaft 45 can be prevented from being applied to the rear lens group frame 7, and the rear lens group frame 7 can be appropriately moved along the optical axis O.

The pressing portion 73 may be formed by using a leaf spring or another elastic member as long as it can press the guide shaft 37 elastically.

As shown in FIG. 1, the camera 10 is provided with a cam lever 9. The cam lever 9 moves the rear lens group frame 7 along the optical axis O, and is rotatably mounted on a projection 48 protruding from an inner wall of the internal space 44 of the movable barrel 4. A cam groove 91 is formed in the cam lever 9, and a pin 64 that passes through the front end 62 a of the link 62 and the long hole 46 is inserted into the cam groove 91. A notch 92 is formed at the tip of the cam lever 9. The notch 92 is hooked on a projection 77 projecting from the upper surface of the rear lens group frame 7.

The cam lever 9 rotates about the projection 48 when the pin 64 moves along the elongated hole 46 when the moving cylinder 4 is extended or retracted.
Due to this rotation, the projection 77 is pushed by the notch 92, and the rear lens group frame 7 moves along the optical axis O.

On the other hand, the width of the notch 92 is larger than the diameter of the projection 77. For this reason, when the rotation direction of the cam lever 9 changes, the width of the
If the cam lever 9 does not rotate more than the dimension of the difference from the diameter of the lens 7, the rear lens group frame 7 does not move in the opposite direction.

The rear lens frame 7 may be moved by rotating the cam lever 9 by providing a projection on the cam lever 9 side and providing a notch or a groove on the rear lens frame 7 side.

The width of the notch 92 is the same as the diameter of the projection 77, and the width of the cam groove 91 is made larger than the diameter of the pin 64. If the cam lever 9 does not rotate more than the difference, the rear lens group frame 7 may not move in the reverse direction.

Next, the operation of the lens guide mechanism 1 will be described.

FIGS. 3 to 7 show horizontal sectional views of the lens barrel of the camera 10. FIG.

As shown in FIG. 3, the fixed cylinder 2
The intermediate cylinder 3 is moved into the intermediate cylinder 3 and the moving cylinder 4
Has been renormalized. At this time, the link mechanism 6 is folded at the rear end portions of the movable barrel 4 and the intermediate barrel 3 so that the camera 1 can be extended even when the movable barrel 4 and the intermediate barrel 3 are fully extended.
It is just stored in the rear end portion that is not exposed outside.
Further, by forming the notch 41 in the movable cylinder 4, the movable cylinder 4 can be retracted into the intermediate cylinder 3 having the guide shaft 37 inside. By efficiently using the internal space 31 of the intermediate cylinder 3, the size of the intermediate cylinder 3 can be reduced, and the size of the camera 10 can be reduced. In addition, moving cylinder 4
Can obtain the maximum size in the intermediate cylinder 3.

When the lens barrel is retracted, the pressing body 76 of the pressing portion 73 of the rear lens frame 7 enters the groove 38 of the guide shaft 37, and the rear lens frame 7 is held by the intermediate cylinder 3.

When the main switch is turned on by the camera 10, as shown in FIG. 2, the motor 29 is driven, and the driving force is increased via the worm gear 28b and the helical gear 28a. The helical gear 25 is transmitted to the gear 25 and starts to rotate. With the rotation, the feed screw 24
Rotates in the fixed barrel 2, and the intermediate barrel 3 moves along the optical axis O and is fed out of the fixed barrel 2. At this time, the rotational drive of the motor 29 is sufficiently decelerated by the screw structure of the feed screw 24 and the insertion hole 33, so that it is possible to omit a part of the deceleration means for deceleration.

When the intermediate cylinder 2 moves, the rear end 61b of the link 61 of the link mechanism 6 moves along the cam groove 27, as shown in FIG. For this reason, with the movement of the intermediate cylinder 2, the rear end 61b of the link 61 moves toward the rear end 62b of the link 62, the intersection angle between the link 61 and the link 62 increases, and the folded link mechanism. 6 extends in the optical axis direction. Therefore, this link mechanism 6
The movable barrel 4 on which the front ends 61a and 62a of the links 61 and 62 are hooked out from the intermediate barrel 3 and moves to a position where a photograph can be taken (WIDE standby position).

On the other hand, the rear lens group frame 7 containing the rear lens group 8 is illuminated while the movable barrel 4 containing the front lens group 5 is held by the intermediate barrel 2 from the retracted position to the WIDE standby position. It moves along the axial direction and moves to the WIDE standby position.

In this state, when the shutter switch is pressed, the motor 29 rotates in the reverse direction, the feed screw 24 rotates in the reverse direction via the worm gear 28b and the helical gears 28a and 25, and the intermediate cylinder 3 is rotated. Be relegated.

As shown in FIG. 5, the retraction of the intermediate cylinder 3 causes the link mechanism 6 to contract, and the moving cylinder 4 to be retracted. At this time, the cam lever 9 rotates about the projection 48 toward the retraction side by the retraction operation of the movable cylinder 4. However, since the notch 92 of the cam lever 9 is formed to be larger than the outer diameter of the protrusion 77 of the rear lens frame 7, the rear lens frame 7 does not move by the rotation of the cam lever 9, and It moves together with the intermediate cylinder 3 while being held. For this reason, the front group lens 5 of the movable cylinder 4 approaches the rear group lens 8 of the rear group lens frame 7, and the front group lens 5
In addition, appropriate focusing can be performed in the optical system of the rear lens group 8, and wide-angle photographing can be performed.

The camera 10 is used to perform telephoto shooting.
Is performed, the motor 29 is driven, and the feed screw 24 is rotated through the worm gear 28b and the helical gears 28a and 25. Due to the rotation, the intermediate cylinder 3 moves along the optical axis O and is fed to the fixed cylinder 2.

As the intermediate cylinder 2 is extended, the rear end 61b of the link mechanism 6 moves along the cam groove 27 and approaches the other rear end 62b as shown in FIG. For this reason,
The intersection angle between the links 61 and 62 increases, and the link mechanism 6 extends in the optical axis direction. As a result, the movable barrel 4 is further extended from the intermediate barrel 3, and the position (TE) at which telephoto shooting is possible.
(LE standby position).

On the other hand, since the rear lens group frame 7 containing the rear lens group 8 is hooked on the cam lever 9 which is axially mounted on the movable barrel 4, the pin 64 is moved with the extension of the movable barrel 4.
The cam lever 9 is pivoted by the movement of, and moves forward along the optical axis O. At this time, the pressing body 7 of the rear group lens frame 7
6 moves in the axial direction while climbing over the groove 38 while being pressed against the outer peripheral surface of the guide shaft 37. Then, when the movable cylinder 4 moves to the TELE standby position, the pressing body 76 enters the groove 38 at the forefront of the guide shaft 37,
It is held by the intermediate cylinder 3. By the movement of the movable barrel 4 to the TELE standby position, the magnification change by the lens driving device 1 is completed.

In this state, when the shutter switch is pressed, the motor 29 rotates in the reverse direction, the feed screw 24 rotates in the reverse direction via the worm gear 28b and the helical gears 28a and 25, and the intermediate cylinder 3 is retracted. .

As shown in FIG. 7, the retraction of the intermediate cylinder 3 causes the link mechanism 6 to contract, and the moving cylinder 4 to be retracted. At this time, the cam lever 9 rotates to the retraction side by the retraction operation of the movable cylinder 4. However, since the notch 92 of the cam lever 9 is formed to be larger than the outer diameter of the protrusion 77 of the rear lens frame 7, the rear lens frame 7 does not move by the rotation of the cam lever 9, and It moves together with the intermediate cylinder 3 while being held. Therefore, the moving cylinder 4
The front lens group 5 comes close to the rear lens group 8 of the rear lens group frame 7, so that proper focusing can be performed in the optical systems of the front lens group 5 and the rear lens group 8, and telephoto shooting can be performed.

FIG. 8 shows the locus of movement of the front lens group 5 and the rear lens group 8 when the intermediate cylinder 3 is extended.

As shown in FIG. 8, when the intermediate barrel 3 is extended from the collapsed position, the front lens group 5
The rear lens group 8 is also extended forward of the camera 10.
At this time, between the retracted position and the WIDE standby position Z1, the rear lens group frame 7 is held by the intermediate cylinder 3, and the rear lens group 8 moves in parallel with the intermediate cylinder 3 by the same amount of movement. Further, the front group lens 5 moves together with the movable barrel 4.

When the intermediate barrel 3 is further extended from the WIDE standby position Z1, the rotation of the cam lever 9 causes the rear lens frame 7 to move more than the intermediate barrel 3 and the front lens 8. Then, the intermediate cylinder 3 is moved to the TELE standby position Z.
5, the pressing body 76 enters the groove 38, and the rear lens group frame 7 is held by the intermediate cylinder 3. When shutter release is performed in this state, the intermediate cylinder 3 is retracted for focusing. At this time, the rear lens group 8
As shown by a dashed line X5 in FIG. 8, it moves together with the intermediate cylinder 3, and by this movement, the distance from the front lens group 5 is reduced, and focusing is properly performed.

Then, the intermediate cylinder 3 is moved to the TELE standby position Z5.
When the zoom lever of the camera 10 is operated in order to perform wide-angle shooting in a state in which the intermediate cylinder 3 is extended, the intermediate cylinder 3 is retracted by the driving of the motor 29 and the rotation of the feed screw 24, and the link mechanism 6 is moved by the accompanying contraction of the link mechanism 6. Cylinder 4
Is performed. At this time, the rear group lens frame 7 hung on the cam lever 9 moves along the optical axis O together with the movable barrel 4, and the pressing body 76 enters the groove 38 of the guide shaft 37 (for example, a WIDE standby position). Stop at Z1). As a result, zooming in the optical system of the front lens group 5 and the rear lens group 8 is performed.

In this state, when the shutter switch is pressed, the motor 29 rotates in the reverse direction, the feed screw 24 rotates in the reverse direction via the worm gear 28b and the helical gears 28a, 25, and the intermediate cylinder 3 is extended. In addition, due to the extension of the intermediate cylinder 3, the link mechanism 6 is extended, and the movable cylinder 4 is extended. At this time, the cam lever 9 rotates to the feeding side by the feeding operation of the movable cylinder 4. However, since the notch 92 of the cam lever 9 is formed to be larger than the outer diameter of the protrusion 77 of the rear lens frame 7, the rear lens frame 7 does not move by the rotation of the cam lever 9, and It moves together with the intermediate cylinder 3 while being held.

For this reason, the front lens group 5 of the movable barrel 4 is moved away from the rear lens group 8 of the rear lens group frame 7, so that proper focusing can be performed in the optical system of the front lens group 5 and the rear lens group 8, and the wide angle Shooting becomes possible.

As described above, according to the lens guide mechanism 1 according to the present embodiment, the magnification of the optical system can be changed by moving the rear lens group frame 7 along the optical axis O together with the movable barrel 4. Then, after holding the rear lens group frame 7 in the groove 38 of the guide shaft 37, the optical system can be focused by moving the movable barrel 4 along the optical axis O. Therefore, stepwise zooming can be easily performed by a single driving source. In particular, the present invention is useful for an optical device that performs extension and retraction without rotating the lens barrel.

A pressing member 76 for pressing the guide shaft 37 is also provided.
Can be received by the guide shaft 45. For this reason, it is possible to prevent a rotational force about the second guide shaft from being applied to the rear group lens housing, and to appropriately move the rear group lens housing along the optical axis.

Further, when the intermediate cylinder 3 and the movable cylinder 4 are retracted by being retracted, the link mechanism 6 is folded at the rear end portions of the movable cylinder 4 and the intermediate cylinder 3, and It is stored in the rear end portion that is not exposed to the outside of the camera 10 even at the maximum extension. For this reason, the link mechanism 6 can be housed by efficiently using the space in the camera 10, and the moving cylinder 4 and the intermediate cylinder 3 can be elongated in the optical axis direction. Therefore, the size of the camera 10 can be reduced.

(Second Embodiment) The lens guide mechanism 1 according to the first embodiment relates to a two-stage extension lens barrel in which an intermediate cylinder 3 and a movable cylinder 4 are respectively extended one by one from a fixed cylinder 2. However, the lens guide mechanism according to the present invention is not limited to such a mechanism, and may be a lens guide mechanism relating to three or more stages of zooming in which three or more cylinders extend from the fixed cylinder 2. Even with such a lens guide mechanism, the same operation and effect as those of the lens guide mechanism 1 according to the first embodiment can be obtained.

(Third Embodiment) In the first embodiment and the second embodiment, the lens guide mechanism relating to the camera for photographing using a photographic film has been described. The present invention is not limited to this, and any lens having an optical system including a front lens group and a rear lens group moving along the optical axis may be used as a lens guide for other optical devices such as an electronic still camera and a video camera. It may be a mechanism.

[0058]

As described above, according to the present invention, the following effects can be obtained.

That is, the magnification of the optical system can be changed by moving the rear lens housing along with the front lens housing along the optical axis. Then, after holding the rear lens unit in the groove of the guide shaft, the front lens unit is moved along the optical axis, so that focusing of the optical system can be performed. Therefore, stepwise zooming can be easily performed by a single driving source.

In particular, the present invention is useful for an optical apparatus which performs extension and retraction without rotating the lens barrel.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a camera provided with a lens guide mechanism.

FIG. 2 is a front view of a camera provided with a lens guide mechanism.

FIG. 3 is an explanatory diagram of an operation of a camera provided with a lens guide mechanism.

FIG. 4 is an operation explanatory view of a camera provided with a lens guide mechanism.

FIG. 5 is an operation explanatory view of a camera provided with a lens guide mechanism.

FIG. 6 is an explanatory diagram of an operation of a camera provided with a lens guide mechanism.

FIG. 7 is an operation explanatory view of a camera provided with a lens guide mechanism.

FIG. 8 is an explanatory diagram of a movement locus of an intermediate cylinder, a front group lens, and a rear group lens.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Lens guide mechanism, 10 ... Camera, 3 ... Intermediate cylinder, 37
... Guide shaft, 4 ... Moving cylinder (front group lens housing), 5 ... Front group lens, 7 ... Rear group lens frame (rear group lens housing), 7
3. Pressing part (holding means), 8: Rear group lens.

Claims (1)

[Claims] 1. A lens guide mechanism in a zoom lens optical system that performs at least zooming and focusing by moving at least a front group lens and a rear group lens along an optical axis, wherein the lens guide mechanism is installed in a direction of the optical axis, A guide shaft having a plurality of grooves formed on the surface thereof at predetermined intervals along the optical axis; a front lens housing that accommodates the front lens and moves along the guide shaft; A rear group lens container that accommodates a lens and is movably supported within a certain range in the direction of the optical axis with respect to the front group lens container; Holding means for elastically pressing the surface to hold the rear group lens container at the position of the groove.