JPH02201303A - Lens barrel of zoom lens - Google Patents

Abstract

PURPOSE:To attain zoom driving with a small driving space by forming a driven gear in a nearly spiral area along a track on the peripheral surface of the moving cylinder of a driving gear. CONSTITUTION:The moving cylinder 7 is positioned in a fixed cylinder and allowed to rotate about the fixed cylinder and move linearly in the direction of the optical axis, and the driver gear 7a which engages the driving gear mounted on a zoom driving motor is formed on the outer peripheral surface of the moving cylinder. When the driving gear rotates, the driven gear is rotated through a cam mechanism about the fixed cylinder and also put in linear motion along the optical axis. The driving gear moves drawing a spiral track relatively to the moving cylinder and the driven gear 7a is formed along the track, so the spiral driven gear 7a passes the driving gear actually at all times. Consequently, the limited space is utilized effectively to reduce the size of the lens barrel on the whole.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a zoom lens barrel having a zoom drive means.

[Prior art and its problems]

Conventionally, zoom lens barrels are generally equipped with a cam follower on the outer circumferential wall of the inner tube of two mutually fitting cam tubes, and a spiral cam groove on the outer circumferential wall of the outer tube. It is known that the formation of This is a configuration in which the lens group included in the inner cam barrel is rotated and linearly moved in the axial direction, thereby adjusting the focal length. By the way, some zoom lens barrels extend the lens by transmitting the rotational force of a motor to an inner cylinder via gears. For example, JP-A-59-109005
In the device disclosed in the above publication, an elongated hole is formed in the peripheral wall of a fixed lens barrel so that its major axis runs along the optical axis direction, a cam follower is provided in a cam tube located inside the elongated hole, and a cam follower is provided in a cam tube located outside the elongated hole. A spiral cam groove is formed in the cam cylinder. On the outer periphery of the outer cylinder, teeth of a constant width are formed aligned around the optical axis, forming a driven gear. By meshing this gear with a drive gear attached to a fixed motor, the outer cylinder is rotated and moved in the axial direction, thereby extending the lens. However, since the member having the driven gear itself also moves in the optical axis direction, the driven gear has been formed to have a width at least equal to the amount of movement thereof. Therefore, the driven gear is formed over a fairly large area of the circumferential surface of the outer cylinder, which causes the zoom lens barrel to become larger. The present invention has been devised to effectively solve the conventional technical problems as described above. Therefore, the object is to provide a zoom lens barrel that can be driven for zooming with a small driving space.

[Means to solve the problem]

The lens barrel of the zoom lens according to the present invention is configured as follows in order to achieve the above-mentioned object. That is, it is located within a fixed barrel and has a movement amount that allows rotation relative to the fixed barrel and linear movement in the optical axis direction,
The lens barrel of the zoom lens is formed with a driven gear that meshes with a drive gear attached to a zoom drive motor on the outer peripheral surface of the amount of movement, and this driven gear moves relative to the amount of movement by extending the lens. It is formed in a substantially spiral region along the locus on the circumferential surface of the moving drive gear.

[Effect]

In the above configuration, when the drive gear attached to the drive motor rotates, the cam mechanism causes the amount of movement to rotate with respect to the fixed cylinder and also performs linear movement along the optical axis. That is, it rotates in a spiral manner. The driving gear moves in a spiral trajectory relative to the amount of movement, but the driven gear is formed along that trajectory, so its actual movement is as follows: The spiral driven gear always passes past the drive gear. As described above, in the above configuration, driven gears are formed only in the minimum necessary locations. Therefore, parts that were previously provided in areas where gears were not formed can be
It can be provided within a portion where a gear was conventionally formed. In this way, according to the above configuration, the limited space can be effectively utilized and the lens barrel as a whole can be downsized.

【Example】

An embodiment of the present invention will be described below with reference to FIGS. 1 to 9. 1 and 2 are exploded perspective views of the lens barrel of the zoom lens according to the present invention, FIG. 3 is a vertical sectional view showing the lens barrel of the zoom lens in the wide-angle state, and FIG. 4 is the telephoto state. FIG. The following explanation will be given mainly using FIGS. 1 and 3. As shown in FIG. 1, a male helicoid screw la is formed on the outer periphery of the first lens frame 1 that holds the first lens group. On the other hand, a female helicoid screw 2a is formed on the inner periphery of the cylindrical lens frame holding member 2, and is screwed together with a male helicoid screw la of the first lens frame 1. This holding cylinder 2 is attached to a shutter block 3 that performs focusing and exposure. At that time, although not shown, a rotatable lever of the shutter block 3 and a recess formed in the first lens frame l engage with each other. When this lever rotates, the first lens frame l also rotates, and at the same time moves in the optical axis direction by the action of the helicoid screw to focus on the subject. Further, the shutter block 3 operates integrally with the forward motion m6 consisting of the cylindrical portion 6c and the flange portion 6d.
It is fixed to this forward cylinder 6 with screws. The second lens frame 5 holding the second lens group moves forward t.
T! 16, a conical first cam follower 13
After fitting into a cam groove 6a formed on the peripheral wall of the cylindrical portion of the forward cylinder 6, it is held in the forward cylinder 6 by screwing it to the threaded portion 5a. The cam grooves 6a are spirally formed at three locations on the peripheral wall of the forward cylinder 6, and are wider on the outer circumferential surface side than on the inner circumferential surface side. The peripheral wall of the forward cylinder 6 is inserted into a rotating ring 8 having a zoom encoder contact piece 9 attached to its outer peripheral surface. The inner peripheral surface of the rotating ring 8 has an inner groove 8 extending along the axial direction.
a is formed, and this inner groove 8a engages with the above-mentioned first cam follower 13 located within the cam groove 6a of the forward cylinder 6. On the other hand, an outer groove 8b extending along the axial direction is formed on the outer circumferential surface of the rotating ring 8, and this outer groove 8b is formed by a protrusion formed on the inner circumferential wall of the rotary advance cylinder 7 as a movable cylinder, which will be explained later. 7b (see Figure 3). The rotating ring 8 is held between the forward cylinder 6 and the forward cylinder 6 in the axial direction by fixing the stopper 10 and the metal fitting 11 to the forward cylinder 6 with screws, allowing only rotation. . Metal fitting 1 fixed around the cylindrical portion 6c of the forward cylinder 6
A zoom encoder flexible printed circuit board +2 (hereinafter abbreviated as zoom signal board) having pattern contacts (indicated by thin lines) shown in FIG. Various lens position signals are generated by the sliding movement of the contact piece 9 mentioned above. On the other hand, a cylindrical barrier holding cylinder 21 is fixed to the flange portion of the forward cylinder 6 with screws. This barrier holding cylinder 21
A barrier block 31 is held at the front end, and a light shielding material 22 is adhered to the outer peripheral surface of the rear end. The barrier block 31 has a barrier actuation piece 32 (biased in the entry direction in FIG. 2 by a spring, not shown) that protrudes toward the rear end of the block. When the lens barrel is retracted, it engages with the protrusion 7b of the rotationally advancing cylinder 7. The advancing barrel 6 holding the first lens group, second lens group, zoom encoder, and lens barrier with the above-described configuration is held inside the rotating advancing barrel 7 having a cylindrical shape. A substantially spiral cam dI\ is provided on the inner circumferential surface of the rotation forward cylinder 7.
7d is formed so as to divide the circumferential surface into three equal parts. The cam groove 7d does not penetrate through the wall thickness of the rotary forward cylinder 7, but is formed as a bottomed groove on the inner surface so that the width on the opening side is wider than the width of the groove bottom. There is. Here, FIG. 5 is a developed view of the front end side of the inner surface of the rotary forward cylinder 7, and as shown in the figure, the cam 117d is formed so as to penetrate toward the front end side of the rotary forward cylinder 7 to form an opening. . A rectangular groove having a front end opening is formed at an intermediate position between the openings at the ends of each cam groove surface, and a claw 7C is formed inside the groove. The forward cylinder 6 has a cam groove 7d in a boss 6b formed around a flange portion 6d.
After the conical second cam follower 14 to be engaged with is installed, the cam follower 14 is guided from the subject side (left side in FIG. 3) of the rotating forward cylinder 7 to the cam groove 7d and stored therein. . A first ring 23 is attached to the end of the rotationally advancing cylinder 7. This first ring is formed with a locking piece 23a and a stopper 23b that protrude in the axial direction from an annular member, and has a light shielding material 2 on its inner periphery.
It has 4. The locking piece 23a is attached to the rotationally advancing barrel 7 by engaging the hole formed in the locking piece 23a with the claw 7c. At this time, as shown in FIG. 5, the stopper 23b is fitted so as to fill the front end opening of the cam groove 7d formed in the rotation forward cylinder 7. As shown in FIG. 1, a boss 7g is formed at a position dividing the outer periphery of the rotary forward cylinder 7 into three equal parts, and a second cam follower 14, which is the same as that attached to the forward cylinder 6, is attached to this boss 7g. It is attached. The rotationally advancing barrel 7 connects the attached second cam follower 14 to a cam il 2 formed at three locations on the inner circumferential surface of a cylindrical fixed lens barrel 26 serving as a fixed barrel.
6a and is housed inside it. Cam groove 26
A is a spiral bottomed groove similar to the cam p7a of the rotation forward cylinder 7 described above, and the opening side is wider than the groove bottom. Further, FIG. 6 is a developed view of the front end side of the inner circumferential surface of the fixed lens barrel, and as shown in the figure, the cam groove 26a is
It is formed so as to penetrate through the end of the fixed lens barrel 26 toward the front end of the cylinder to form an opening. In addition, fixed lens barrel 2
A second annular ring is attached to the front end of 6. This second ring is formed with a collar 25a projecting in the axial direction at the end of the annular member, and is mounted so that the stopper 25a fills the end of the cam WIt7a that passes through it. . As shown in FIG. 3, a light shielding material 51 is adhered to the inner surface of the second ring, similar to the first ring. A front cover 40 is attached to the tip of the fixed lens barrel so as to cover this second ring. A pair of gear holding parts 26b are formed on the outer peripheral surface of the fixed lens barrel 26 so as to face each other, as shown in FIG. It is pivoted by. On the other hand, as shown in FIG.
A gear portion 7a is formed so as to mesh with this gear 27 and rotate the rotary advance cylinder 7. Note that the rotary forward barrel 7 has a cam groove 7 with respect to the fixed lens barrel 26, as will be explained later.
In order to move along the path d, the gear portion 7a is also formed in a spiral shape along this trajectory. A flange portion of a guide ring 29 composed of a cylindrical portion and a seven-runway portion is fixed to the end portion of the fixed lens barrel 26 on the camera body 4I side with screws. This guide ring 29
The cylindrical portion fits into the inner circumferential surface of the rotating forward barrel 7, and the fixed lens barrel 2
The rotary forward cylinder 7 is held between the cylinder 6 and the cylinder 6. Further, inside this cylindrical portion, a groove portion 10 formed at the peripheral end of the stopper fitting 10 is provided.
A guide member 30 that engages with a and 10b is fixed. Regarding the zoom lens barrel configured as above,
The operation will be explained below. However, in this case, the initial state is set to the wide-angle side shown in FIG. As a prerequisite for the zoom operation, when the zoom switch is turned on, the rotation of the zoom and the zoom is transmitted to the gear 27 attached to the fixed lens barrel 26 via a reduction gear train (not shown). Therefore, the rotary advance barrel 7 rotates within the fixed lens barrel 6 by the action of the gear portion 7a, but the second cam follower 14 moves along the cam groove 26a, thereby moving the lens group, the second lens group, etc. It also moves in the optical axis direction together with the held forward barrel 6. By the way, the guide member 30 integrally included in the guide ring 29 screwed to the fixed lens barrel 26
However, the groove 10 of the stopper lO screwed to the forward cylinder 6
a and 10b, the rotating forward barrel 7 rotates and moves forward with respect to the fixed barrel 26, whereas the forward barrel 6 only moves linearly with respect to the fixed barrel 26. It is. Therefore, the rotation forward cylinder 7 and the forward movement cylinder 6 rotate relative to each other. By this,
The second cam follower 14 attached to the outer periphery of the flange portion 6d of the forward moving tube 6 slides on the cam groove 7d on the inner circumference of the rotating forward moving tube 7, and the forward moving tube 6 itself moves inside the rotating forward moving tube 7 along the optical axis. and move further forward, and the lun group also moves by the same amount as this movement. At this time, the rotating ring 8 located around the cylindrical portion 6c of the advancing barrel 6 moves integrally with the advancing barrel 6' in the optical axis direction, but the outer groove 8b and the protrusion 7b of the rotating advancing barrel 7 Since the forward cylinder 6 is engaged with the rotary forward cylinder 7, the forward cylinder 6 rotates together with the rotary forward cylinder 7. Then, as the rotating ring 8 rotates with respect to the forward cylinder 6, the I-th cam follower 13 located within the cam groove 6a moves along the cam groove 6a. In other words, the second lens group moves in the optical axis direction at this time as well, and the total amount of movement from the wide-angle side to the telephoto side is equal to the movement of the two second cam followers 14 and the first It can be said that this is the sum of the amounts by which the cam followers 13 each move along the optical axis. In this way, when zooming from the wide-angle side to the telephoto side, the second lens group is connected to the cam groove 6 with respect to the lens group.
The first cam follower 13 moves in the optical axis direction by an amount corresponding to the amount of movement in the optical axis direction. Therefore, the space required in the optical axis direction to move the second lens group can be reduced to about half that of the conventional lens. In addition, in conventional configurations, in order to achieve a certain degree of cam stroke, the torsion angle of the cam groove must be reduced to reduce the amount of rotation, otherwise the zoom speed would be slow.
On the other hand, if the torsion angle was small, the operation would become unstable due to the influence of friction, but with the above configuration, the cam groove can be formed so that the zoom operation can be performed easily and quickly. Become. Further, by forming the driving gear portion in a spiral shape along the movement of the cylinder, the driving space can be kept to a minimum, and this also allows the lens barrel to be configured to be small. Furthermore, since the cam groove extends through the front end of the cylinder to form an opening, it is easy to assemble the lens. on the other hand,
At the most extended position of the lens barrel, the second cam follower, which moves within the cam groove 7d of the rotary forward cylinder 7, is moved by the first ring 2.
The cam groove 26a of the fixed lens barrel 26 is inserted into the stopper 23b of No. 3.
The second cam follower 14 moving within the second ring 25
Since the forward barrel comes into contact with the stoppers 25a, the forward barrel does not come out during zooming. Additionally, the light shielding material can be attached extremely easily. As shown in FIG. 4, during zooming, the rotary forward barrel 7 protrudes forward beyond the front cover attached to the front of the fixed lens barrel 26, but the first ring 23 is attached to the tip of the rotary forward barrel 7. Therefore, its internal structure cannot be seen. The cam grooves 6a, 7d, and 26a formed in the forward movement member 7 and the fixed lens barrel 26 are as shown in FIGS. 5 and 6 respectively for 7d and 26a, and the same for 6a. In terms of their functions, they are classified into a zoom operation area I and a barrier operation area (2). Assuming that the lens barrel is now in the wide-angle state, the gear 27 is moved to further retract the rotary forward barrel 7 as shown in FIG. When the rotary ring 8 is rotated in the B direction, the rotary ring 8 also rotates in the B direction with the rotation of the rotary advance cylinder 7. At this time, the barrier actuating portion 32 of the barrier block 31 that has been drawn into the body comes into contact with the protruding portion 7b of the rotary forward cylinder 7, and the barrier actuating portion 32
The barrier is closed by rotating in the direction B with the rotation of the protrusion 7b. On the other hand, with the barrier closed, the rotating forward barrel 7 is moved in six directions as shown in FIG. When rotated, the rotating ring 8 also rotates in six directions along with the rotating forward cylinder 7. As mentioned above, since the barrier actuating section 32 is biased in six directions by a spring (not shown),
At the stage when the cam follower is moving in the barrier operating area of the cam groove, the barrier operating portion 3 is attached to the protrusion 7b of the rotating forward barrel 7.
2 follows, during which the barrier is opened. When the cam follower enters the zoom operation area of the cam groove, the barrier actuating part 32 is in the barrier release side position, so it does not follow the protrusion 7b of the rotary forward cylinder 7 any more, but changes its position to the spring. It is held by a biasing force. During the extending and retracting operations of the lens barrel as described above, the rotating forward barrel 7 always moves in the optical axis direction while being fitted into the fixed lens barrel 26, and the gear portion 7a of the rotating forward barrel 7 is formed. In this position on the camera body side, the rotary forward barrel 7 is always kept in a fitted state with the guide ring 29. Therefore, the rotary advance barrel 7 is prevented from tilting with respect to the fixed lens barrel 26 due to the moment of the gear drive unit generated when the lens barrel is extended or the weight of the lens itself that is extended. Here, the operation of the zoom encoder 12 will be explained using FIG. 9. First, the rotating ring 8 is connected to the rotating forward cylinder 7.
However, since the metal fitting 11 is fixed to the forward cylinder 6, the contact piece 9 attached to the rotating ring 8 and the metal fitting 1
Relative rotation is performed between the zoom signal board 12 attached to the zoom signal board 1 and the zoom signal board 12 attached to the zoom signal board 12. FIG. 9 is a developed view of the zoom signal board 12 and the contact piece 9. When the lens barrel is in a wide-angle state, the contact piece 9 moves to the position 99a indicated by the solid line, and the tip of the contact piece 9 moves to position S.) , when in the telephoto state, it moves to position 9b indicated by a broken line (the tip of contact piece 9 moves to position X). Although not shown, the tip of the contact piece 9 moves to position U when the barrier is closed. In this way, the contact piece 9 can take each position of X'=u on the zoom signal board depending on the zoom position, but at these positions, the pattern contacts (represented by thin lines) of the conductor pattern of the zoom signal board 2 are ), the signals from the ground contacts A, B, C, D, and FG are sent to the circuit inside the camera through the connector H. For example, in this figure, the contact piece position 9b when the lens barrel is in the telephoto state represents the position for aligning the lens barrel and the zoom signal board, and in this case, the zoom position is set to the telephoto side. The position is adjusted by determining the continuity state between contact E and ground A when adjusted to the end, and monitoring the position where it turns off. Note that this adjustment position does not necessarily need to be performed at the telephoto end, and may be set at another position. In addition, if the pattern contacts are configured as shown in this figure, detection of D and E can be performed with one tip of the contact piece as distinguished by hatching in the figure, so the tip of the piece can be used just for position adjustment. There is no need to increase

[Brief explanation of the drawing]

1 and 2 are exploded perspective views of a lens barrel of a zoom lens according to an embodiment of the present invention, FIG. 3 is a vertical sectional view of the lens barrel of the zoom lens in a wide-angle state, and FIG. 4 is a zoom lens 5 is a developed view of the end of the rotary advancing section, FIG. 6 is a developed view of the front end of the fixed lens barrel, and FIG. 7 is a developed view of the front end of the fixed lens barrel. Figure 8 is the right side view of Figure 3 in the zoom operation area (only inside the rotating forward barrel), Figure 9 is the expansion of the zoom signal board. It is a diagram. l...second lens frame, la...male helicoid screw,
2...Second lens frame holding cylinder, 2a...Female helicoid screw, 3...Shutter block, 5...Second lens frame, 5a...Threaded portion, 6...Advance lever, 6a ...Cam groove, 6b...Boss, 6c...Cylindrical part, 6d...
Flange portion, 7...Rotating advance cylinder as a moving cylinder, 7a
...Gear part, 7b...Protrusion, 7c...Claw, 7d.
...Cam 1? ri, 7g...boss, 8...rotating ring,
8a...Inner groove, 8b...Outer groove, 9...Zoom encoder contact piece, lO...stopper, 10a, IOb
... Groove portion, 11... Metal fitting, 12... Flexible printed circuit board for zoom encoder, 13... First cam follower, 14... Second cam follower, 21...
... Barrier holding cylinder, 22 ... Light shielding material, 23 ... First
Ring, 23a... Locking piece, 23b... Stopper, 24... Light shielding material, 25... Second ring, 25a...
...Stopper, 26...Fixed lens barrel as a fixed barrel,
26a...Cam groove, 26b...Gear holding part, 27.
...Gear, 28...Pin, 29...Guide ring,
30... Guide member, 31... Barrier block, 3
2...Barrier operating piece, 4,0...Front cover 41.
...Body (,42...Film surface, 5I...Light shielding material patent Applicant: Minolta Camera Co., Ltd. Agent)
Person Patent attorney Qingbai Ao (1 other person) Figure 5 Figure 6 Cause Figure 7 A Figure 8

Claims (1)

[Claims] (1), located within the fixed tube (26),
) is provided with a movable barrel (7) that is allowed to rotate with respect to the zoom drive motor and to move linearly in the optical axis direction. In the lens barrel of the zoom lens, the driven gear (7a) is configured to move the driving gear (27) relative to the movable barrel (7) by extending the lens. A lens barrel for a zoom lens, characterized in that a tube (7) is formed in a substantially spiral region along a locus on the circumferential surface.