JPH07181361A - Lens-barrel - Google Patents

Abstract

PURPOSE:To provide a lens-barrel having a short length in the recessed state which can realize a large displacement quantity in optical axial direction with the structure of a small number of members. CONSTITUTION:In a lens-barrel having a fixed frame 34, lens groups arranged in such a manner as to be capable of protruding and recessing in the optical axial direction on the inner circumferential side of the fixed frame 34, lens holding frames for holding the lens groups such as a second group frame 1, a third group frame 5, a fourth group frame 13 and a fifth group frame 19, and a driving means provided on the inner circumference of the fixed frame 34 to protrude and recess the lens holding frames in the optical axial direction, it is also provided with keys 40, 42 for stopping the rotation around the optical axis of the lens holding frames, and reinforcing the strength of the lens-barrel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel, and more particularly to a lens barrel in which a plurality of lens groups are arranged so as to be movable back and forth in the optical axis direction.

[0002]

2. Description of the Related Art Conventionally, there are various lens barrels for zooming by rotating a cam frame housed inside a fixed frame and moving a holding frame of a lens group in the optical axis direction. Proposed.

In such a lens barrel, a rotation stopping member for the lens holding frame is required in order to prevent the lens holding frame from rotating due to the rotation of the cam frame. The one having such a rotation stopping member and a reinforcing member for reinforcing the strength of the lens barrel is disclosed in Japanese Patent Application Laid-Open No. 2-20130.
As described in Japanese Patent Laid-Open No. 5, a straight guide member is provided as the rotation stopping member and a guide ring is provided as a reinforcing member, and the separate members are thus provided so as to fulfill their respective functions. Further, a groove is formed in the frame member for which the rotation is to be stopped, and the rotation is stopped by engaging with the linear guide member.

[0004]

However, like the one described in Japanese Patent Application Laid-Open No. 2-201305, if the rotation stop of the holding frame and the strength reinforcement of the lens barrel are performed using different members, respectively. Naturally, the number of parts increases correspondingly, and the frame structure becomes complicated.

Further, a groove is provided on the frame for which rotation is to be stopped,
When the rotation stopping member is fitted to stop the rotation, the length of the rotation stopping member needs to be 1/2 or more of the moving amount of the frame,
In order to stop the rotation of the frame having a large amount of movement, a rotation stop member correspondingly long is required. As a result, the rotation stopping member projects from the lens barrel in the collapsed state, and the length of the lens barrel in the collapsed state cannot be shortened. On the contrary, if the length of the lens barrel in the collapsed state is shortened, the length of the rotation stopping member also becomes short, and it becomes impossible to stop the rotation of the frame having a large movement amount.

The present invention has been made in view of the above circumstances, and provides a lens barrel having a short length in a retracted state, which can realize a large displacement amount in the optical axis direction with a small number of member configurations. Is intended.

[0007]

In order to achieve the above object, the lens barrel according to the present invention comprises a fixed frame,
A lens group arranged in the inner circumference of the fixed frame so as to be movable back and forth in the optical axis direction, and a lens holding frame for holding this lens group,
A lens barrel provided on the inner circumference of the fixed frame, and driving means for moving the lens holding frame forward and backward in the optical axis direction. The lens barrel further prevents rotation of the lens holding frame around the optical axis, and the lens. A reinforcing member for reinforcing the strength of the lens barrel is provided.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an exploded perspective view showing a zoom lens barrel according to an embodiment of the present invention with the lens barrel stretched in the optical axis direction, and FIG. 2 is an exploded perspective view showing details of essential parts of a lens holding frame.

The zoom lens barrel includes, in order from the front side (subject side) along the optical axis, the first group frame 38 holding the first group lens, and the second group frames 1, 3 holding the second group lens. It has a third group frame 5 holding a group lens, a fourth group frame 13 holding a fourth group lens, and a fifth group frame 19 holding a fifth group lens.

The second group frame 1, the third group frame 5, the fourth group frame 13, 5
A cam frame 24 is arranged on the outer peripheral side of the group frame 19, and a first zoom frame 31 into which the first group frame 38 is screwed via a screw portion 39 is arranged outside the cam frame 24. A fixed frame 34 is arranged on the outer peripheral side of the first zoom frame 31, and the fixed frame 34 is fixedly attached to the lens plate 46.

The second group frame 1 has a peripheral wall-shaped projection 1c provided in a predetermined range in the circumferential direction from the end surface on the rear side of the optical axis (camera body side) and extending in the optical axis direction. A key groove 1b for stopping rotation is engraved on the outer peripheral surface side, and a key groove 1d is engraved on the inner peripheral surface side in parallel with the optical axis, and a rod 2 is extended in the optical axis direction. The second group frame 1 has three pins 3 facing outward at three circumferentially divided positions on its circumferential surface.
And the protrusions 30 are provided at equal positions in the circumferential direction on the front side (subject side) in the optical axis direction with respect to the pin 3.
Is provided and has a key groove 1a (see FIG. 3) parallel to the optical axis.

The third group frame 5 has substantially cylindrical bearings 7, 8 and 9 having sleeves 6 at both ends, which are arranged at substantially three equal positions in the circumferential direction, and the bearing 8 among them has a shaft. A projecting portion 23 that projects to the rear side in the direction (camera body side) is provided, and the pin 12 that projects in the outer diameter direction is integrally provided on this projecting portion 23. Further, a guide protrusion 10 extending rearward in the optical axis direction is provided on the third group frame 5 at a position between the bearing 7 and the bearing 8 along the circumferential direction, and the guide protrusion 10 is provided between the bearing 8 and the bearing 9. Guide protrusion 11 extending to the rear side of the optical axis at a position
Is provided.

The fourth group frame 13 has a pin 15 integrally protruding from the peripheral surface in the outer diameter direction, and a groove portion 16 for preventing rotation is formed on the peripheral surface to further prevent light from being generated. The rod 14 is bonded to the front side parallel to the axis, and the groove 16 and the rod 14 are arranged at substantially equal positions in the circumferential direction. A motor 17 for adjusting the diaphragm is attached to the fourth group frame 13.
A strip-shaped substrate 18 extends from 7.

In the fifth group frame 19, the pin 22 is integrally projected in the outer diameter direction and the groove portion 20 for stopping rotation is provided.
Is provided, and a rod 21 that is forward and parallel to the optical axis is further adhered to the outer peripheral side, and the groove portion 20 and the rod 21 are arranged at substantially equal positions in the circumferential direction.

The cam frame 24 is a cylindrical member in which several bottomed cams 26 constituting a cam mechanism are engraved on the inner peripheral surface of the cam frame 24. The inner peripheral surface of the cam frame 24 is on the rear side of the optical axis (on the side of the photographer). ) Is provided with a partial internal gear 29 in the circumferential direction. Further, on the outer peripheral surface of the cam frame 24, several bottomed cams 25 that also constitute the cam mechanism are engraved, and an encoder 28 is attached, and two pins are provided from the end portion on the rear side of the optical axis. Two
7 is integrally projected.

The first zoom frame 31 has three inner peripheral surfaces.
The straight grooves 33 of the book are formed at three equally divided positions in the circumferential direction, the pins 50, 51, 52 are integrally projected from the inner peripheral surface thereof, and the rear end portion has a substantially rectangular shape. Protrusion 4
9 extends in the axial direction, and the protrusion 49 has the first
A pin 32 is provided separately from the zoom frame 31.

The fixed frame 34 is a cylindrical member having a cam 112 on the inner peripheral surface, a ring 36 is fitted to the front end in the optical axis direction, and a photo reflector (PR) is mounted on the outer periphery.
A substrate 35 having 48 is attached. Further, from the rear end surface of the fixed frame 34 in the optical axis direction, several bosses 37 are provided so as to project in the circumferential direction.

Further, the first group frame 38 is provided with a threaded portion 39 for attachment to the first zoom frame 31 on the peripheral surface on the front side of the optical axis.

The lens plate 46 is a plate-shaped member having holes 47 at four corners, and has a thin light-shielding groove 4 in a direction perpendicular to the optical axis.
The key 40, which is a reinforcing member in which a large number of 1 are engraved, and the key 42, which is the same reinforcing member to which the pinion gear 43 extending in the optical axis direction is attached, are perpendicular to the front surface of the lens plate 46. It is attached so that. Also,
The lens plate 46 includes a zoom motor 45, which is a drive source.
And a second gear box 44 having a gear train for transmitting the driving force of the zoom motor 45, and the final gear of this gear train meshes with the pinion gear 43 mounted on the key 42. is doing.

Next, a method of stopping rotation of each lens group around the optical axis will be described. The third group frame 5 has two bearings 8
The rod 2 of the group frame 1 is fitted, the rod 14 of the fourth group frame 13 is fitted to the bearing 7, and the rod 21 of the fifth group frame 19 is fitted to the bearing 9, that is, the bearings 7, 8, This 3 with 9
Based on the group frame 5, the second group frame 1 is supported on the front side of the optical axis, and the fourth group frame 13 and the fifth group frame 19 are supported on the rear side of the optical axis.

The guide projection 1 provided on the third group frame 5
The base end portion 11a of No. 1 has a key groove 1d provided in the second group frame 1
The rotation of the second group frame 1 is stopped by fitting it with, and the rotation of the fourth group frame 13 is stopped by fitting the guide projection 11 with the groove portion 16 provided in the fourth group frame 13, and The rotation of the fifth group frame 19 is stopped by fitting the guide protrusion 10 and the groove portion 20 provided in the fifth group frame 19.

FIG. 3 is a front view showing the lens unit 73 attached to the lens plate 46, and FIG. 4 is a perspective view showing the keys 40 and 42 attached to the lens plate 46. As described above, the keys 40 and 42 extending to the front side in parallel to the optical axis direction are fixed to the front surface of the lens plate 46 via the key mounting portions 40a and 42a provided on the respective keys. The key 40 is provided with a plurality of fine light shielding grooves 41 for light shielding inside.

A light-shielding groove similar to that of the key 40 is also provided inside the key 42, and the arm portion 9 extends from the key 42.
4 extends in the circumferential direction. The arm portion 94 is provided with a pinion gear 43 having an axial length so as to be sandwiched between the arm portion 94 and the lens plate 46, and the lower portion of the pinion gear 43 has a different gear diameter.

Further, since the pinion gear 43 has an axial length, there is a possibility that the pinion gear 43 may bend, and it is made of metal in order to avoid such bending.

The keys 40 and 42 are fitted into the key grooves 1a and 1b provided in the second group frame 1, respectively, so that the keys 2 and
The rotation of the group frame 1 is restricted. Also, these keys 40,
When the key 42 is made of metal, the lens unit 73 can also be reinforced.

The keys 40 and 42 can be formed by, for example, aluminum die casting, zinc die casting, etc., and each component of the frame member including the second group frame 1,
It can also be molded from a lighter weight and less rigid plastic material or the like. By doing so, the keys 40 and 42 substantially guarantee the rigidity of the entire lens unit 73, and can serve as a positioning reference for each component of the lens barrel.

The first zoom frame 31 has three rectilinear grooves 33 provided on its inner peripheral surface and parallel to the optical axis direction.
By engaging with three protrusions 30 provided on the outer periphery of the second group frame 1 on the optical axis front side, rotation around the optical axis is restricted.

As described in detail above, according to such an embodiment, the rotation of the frame for holding the lens group and the strength reinforcement of the lens barrel are performed by using the same key. Therefore, the configuration of the lens barrel can be simplified.

As a method of stopping rotation, since the lens holding frame whose rotation is stopped by the above keys is used to regulate the rotation of the other lens holding frames, a short key is used to move the frame with a large movement amount. The rotation can be stopped. As a result, the length of the lens barrel in the collapsed state can be shortened.

[0030]

As described above, according to the present invention, a lens barrel having a short length in the retracted state can be realized with a large amount of displacement in the optical axis direction with a small number of member configurations.

[Brief description of drawings]

FIG. 1 shows a zoom lens barrel showing an embodiment of the present invention,
The exploded perspective view expanded and shown in the direction of an optical axis.

FIG. 2 is an exploded perspective view showing the second group frame, the third group frame, the fourth group frame, and the fifth group frame of the above-mentioned embodiment in an enlarged manner in the optical axis direction.

FIG. 3 is a front view showing a lens unit attached to the lens plate of the embodiment.

FIG. 4 is a perspective view showing a key attached to the lens plate of the above embodiment.

[Explanation of symbols]

 1 ... 2 group frame (lens holding frame) 5 ... 3 group frame (lens holding frame) 13 ... 4 group frame (lens holding frame) 19 ... 5 group frame (lens holding frame) 38 ... 1 group frame (lens holding frame) 24 ... Cam frame 31 ... First zoom frame 34 ... Fixed frame 40, 42 ... Key (reinforcing member) 46 ... Lens plate

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[Procedure amendment]

[Submission date] February 24, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

The second group frame 1, the third group frame 5, the fourth group frame 13, 5
A cam frame 24 is arranged on the outer peripheral side of the group frame 19, and a first zoom frame 31 into which the first group frame 38 is screwed via a screw portion 39 is arranged outside the cam frame 24. A fixed frame 34 is arranged on the outer peripheral side of the first zoom frame 31, and the fixed frame 34 is fixedly attached to the lens plate 46 .

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

The fifth group frame 19 has a pin 22 integrally projecting in the outer diameter direction and a groove portion 20 for stopping rotation.
Is provided, and a rod 21 that is forward and parallel to the optical axis is further adhered to the outer peripheral side, and the groove portion 20 and the rod 21 are arranged at substantially equal positions in the circumferential direction.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

The key 40 and the key 42 are fitted into the key grooves 1b and 1a provided in the second group frame 1, respectively, so that the keys 2 and
The rotation of the group frame 1 is restricted. Also, these keys 40,
When the key 42 is made of metal, the lens unit 73 can also be reinforced.

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 5]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

[Procedure correction 6]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

Claims (1)

[Claims] 1. A fixed frame, a lens group arranged so as to be movable back and forth in the optical axis direction on the inner circumference of the fixed frame, a lens holding frame for holding the lens group, and provided on the inner circumference of the fixed frame. A lens barrel having a driving means for moving the lens holding frame forward and backward in the optical axis direction, further preventing rotation of the lens holding frame around the optical axis and reinforcing the strength of the lens barrel. A lens barrel having a reinforcing member for performing the above.