JP2822341B2 - Zoom lens barrel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens barrel having an encoder mechanism.

[0002]

2. Description of the Related Art In order to transmit focal length information from a zoom lens barrel to a CPU of a camera body, the rotation of the drive barrel corresponds to the focal length of the zoom lens. A printed board having a pattern different depending on the position is provided, and a brush in contact with the printed board is hung down from a fixed lens barrel, and an encoder mechanism for reading the pattern after rotational movement with the brush and outputting as a rotation amount, that is, a focal length is provided. Zoom lens barrels are already known.

[0003] In a conventional zoom lens barrel, since a plurality of lens groups (for example, two groups) are provided, a focal length changes with a zoom operation. In order to always adjust this focal length to the film surface of the camera, the mutual distance of each lens group is changed in a predetermined relationship with respect to the film surface of the camera. However, in this configuration, since one of the lens groups cannot be moved alone, the back adjustment, that is, the operation of aligning the image surface of the zoom lens with the print surface of the camera during assembly is performed by the fixed lens barrel of the zoom lens and the camera body. (Mounting surface) by holding washers of different thicknesses between them and maintaining an appropriate gap between them. However, this back adjustment has to remove the zoom lens barrel from the camera every time a washer is inserted, and the workability is poor.

On the other hand, in a certain kind of zoom lens barrel, the back adjustment is not performed with a washer interposed between the fixed barrel and the camera body. By providing a switching means that moves integrally in the optical axis direction, the back adjustment can be performed by operating the switching means and rotating the driving lens barrel with respect to the fixed lens barrel. According to this back adjustment, workability during assembly can be greatly improved.

[0005]

However, when the zoom lens barrel has the above-described encoder mechanism, the drive mirror for the fixed barrel is rotated by rotating the drive barrel for back adjustment. The phase of the cylinder, that is, the detection origin of the encoder mechanism (the point where the rotation amount is zero) is shifted, and as a result, there arises a problem that the output signal of the encoder mechanism does not correspond to the zoom position, that is, the position of each lens group.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a zoom lens barrel with improved assembling workability in which back adjustment can be easily performed.

[0007]

SUMMARY OF THE INVENTION A zoom lens barrel according to the present invention comprises a first lens means (3, L1), a second lens means (6, L2), a fixed lens barrel (4), A driving lens barrel (2) that performs a zoom operation by rotating with respect to the fixed lens barrel (4); and a driving force generated by rotation of the driving lens barrel (2) is applied to the first lens means (3, L1). And first driving force transmitting means (3d, 2d) for transmitting the first lens means (3, L1) in the optical axis direction with respect to the film surface of the camera (1); The driving force due to the rotation of 2) is transmitted to the second lens means (6, L2), and while changing the distance to the first lens means (3, L1), the second lens means (6) is changed. , L2) in the direction of the optical axis, second driving force transmitting means (5d, 6a), the driving lens barrel (4) and the second driving force transmitting means (5). Driving force transmitting means (5d, 6a)
And the transmission of the driving force is stopped, and the first
Of the second lens means (6, L1).
L2), transmission control means (10, 11) for making it movable in the optical axis direction relative to the film surface;
One of the driving lens barrel (2) and the fixed lens barrel (4) is provided on one of the lens barrels. A pattern means (35) which is relatively rotated and moved together with the lens barrel, and a relative rotation amount of the one lens barrel is detected by reading the pattern means (35) which is provided on the other lens barrel and rotated relatively. Detection means (34a, 34b, 34c, 34d, 34e) and the pattern means (3
Moving means (33, 4) for moving in the relative rotation direction of 5)
1, 42, 33b, 36) are provided.

[0008]

In the zoom lens barrel according to the present invention, one of the driving barrel provided with the pattern means and the fixed barrel is provided with the other of the driving barrel and the fixed barrel. Since the moving means for moving the detecting means provided in the cylinder in the rotation direction of the pattern means is provided, even if the phases of the fixed lens barrel and the driving lens barrel are shifted by the back adjustment,
By moving the detection means in the rotation direction of the pattern means, the detection origin of the encoder mechanism can be moved to the original position. Thereby, the output signal of the encoder mechanism with respect to the zoom position of the zoom lens can be accurately matched.

[0009]

Embodiments of the present invention will be described below in more detail with reference to the drawings. FIG. 1 is a perspective view of a zoom lens barrel according to the present invention. In FIG. 1, a cylindrical drive lens barrel 2 is rotatable coaxially inside a cylindrical fixed lens barrel 4 attached to a camera 1 only partially shown. By rotating the drive lens barrel 2 as described later with reference to FIG. 4, the first lens group holding member 3 moves in the optical axis direction.

[0010] An annular gear 2 b is formed on the outer periphery of the drive lens barrel 2, and the gear 2 b is engaged with the gear 20 of the gear train 22. The gear train 22 transmits the rotation of a motor 21 attached to the camera 1. Accordingly, the drive lens barrel 2 is rotated by the rotation of the motor 21.

A part of the outer periphery of the end of the fixed lens barrel 4 is cut out, and the cutout 4c is provided with an encoder mechanism as described below. A shelf 4d is provided at the camera-side end of the cutout 4c. A block 33 having a long hole 33a extending in the circumferential direction is screwed onto the shelf 4d by two screws 41, 42 via the long hole 33a. The block 33 has an arm 33b extending in the optical axis direction. The arm 33b has an opening 33c (FIG. 3). The upper side of the arm portion 33b is in contact with a projection 2c provided on the outer periphery of the driving lens barrel 2.

A brush holder 34 having a slot 34h extending in the optical axis direction is provided on the arm 33b.
It is attached by an eccentric pin 36 via 4h.
An inhibitor (not shown) is provided on the side of the arm 33b opposite to the block 33, and the inhibitor does not move the brush holder 34 in the optical axis direction with respect to the arm 33b.

The brush holder 34 extends in the circumferential direction.
Book metallic brushes 34a, 34b, 34c, 34d,
34e is attached. The tip of the brush is the drive barrel 2
Printed board 35 attached to the outer periphery of the board by bonding or the like
And the rear end is connected to a CPU (not shown) of the camera body by wiring (not shown). In addition,
The printed board 35 constitutes the pattern means, and the brush 34
a, 34b, 34c, 34d, and 34e constitute detection means. The encoder mechanism includes a printed board 35 and brushes 34a, 34b, 34c, 34d, 34e. The configurations of the arm 33b and the brush holder 34 will be described later with reference to FIG. 3, but the encoder mechanism is well known and will not be described in detail.

Next, the structure of the zoom lens barrel according to the present invention will be described. FIG. 4 is a sectional view in the optical axis direction showing the zoom lens barrel when the first and second lens groups are at the wide-angle position (retracted position).

A substantially cylindrical fixed lens barrel 4 fixed to the camera 1 has a straight groove 4b formed in its peripheral wall in the optical axis direction. On the outer periphery of the fixed lens barrel 4, a circular drive lens barrel 2 is provided.
However, it is rotatable around the optical axis with respect to the fixed barrel 4, but is fitted so as not to move in the optical axis direction. A cam groove 2d is formed on the peripheral wall of the driving lens barrel 2 in a direction oblique to the circumferential direction, that is, in a spiral shape. Further, an annular gear 2b is formed on the outer peripheral surface of the driving lens barrel 2, and the gear 20 driven by the motor 21 in FIG. Therefore, when the gear 20 is rotated by the motor, the driving lens barrel 2 as the driving means is rotated.

A first lens group holding member 3 is provided inside the fixed lens barrel 4 so as to be movable in the optical axis direction. The first lens group holding member 3 is configured such that an annular portion 3f is connected to an outer periphery of a circular tube portion 3e extending in the optical axis direction.
Furthermore, a partial circular tube portion 3g is attached to a part of the outer periphery of the annular portion 3f in parallel with the circular tube portion 3e, and the outer peripheral surfaces of the annular portion 3e and the partial circular tube portion 3g are respectively fixed to the fixed lens barrel 4. It is configured to be slidable by contact. The first lens means L1 and the first lens group holding member 3 constitute the first lens means.

The cam groove 2d of the driving lens barrel 2 and the rectilinear groove 4b of the fixed lens barrel 4 are implanted in the partial cylindrical portion 3g of the first lens group holding member 3 for holding the first lens group L1. The inserted cam follower 3d is inserted in the radial direction. Therefore, the first
The lens group holding member 3 moves forward and backward in the optical axis direction without rotating in the optical axis direction with the rotation of the drive lens barrel 2 around the optical axis. As shown in FIG. 4, a cam hole 3c extending in the optical axis direction is formed in the circular tube portion 3e of the first lens group holding member 3. The cam follower 3d and the cam groove 2d constitute first driving force transmitting means.

The fixed lens barrel 4 is formed with a cam hole 4a obliquely extending in the circumferential direction at a position not intersecting with the above-mentioned straight groove 4b. Further, a rotating cylinder 5 that is rotatable about the optical axis but does not move in the optical axis direction with respect to the first lens group holding member 3 is fitted around the outer periphery of the first lens group holding member 3, The outer peripheral surface of the cylinder 5 is formed with a cam hole 5b obliquely extending in the circumferential direction.

On the inner periphery of the first lens group holding member 3, a second lens group holding member 6 for holding the second lens group L2 is provided.
Are slidably fitted in the optical axis direction. On the outer periphery of the second lens group holding member 6, a cylindrical cam follower 6b is implanted in the radial direction. The cam follower 6b passes through the cam hole 3c and the cam hole 5b. The second lens unit and the second lens group holding member 6 constitute a second lens unit, and the cam hole 5b and the cam follower 6a constitute a second lens unit.
Of the driving force transmission means.

A cylindrical cam follower 5a which engages with the cam hole 4a of the fixed lens barrel 4 is mounted on the support member 10 radially outward. The support member 10 is screwed and attached to the rotating cylinder 5 through two notches 9 in elongated holes (not shown). The rotating cylinder 5 is moved to the first position by elastic means (not shown).
Of the lens group holding member 3 in the circumferential direction. Therefore, when the screw 11 is tightened, the cam follower 5a moves in the cam hole 4a with the movement of the first lens group holding member 3 in the optical axis direction, thereby rotating the rotary cylinder 5 around the optical axis.

When the screw 11 is loosened at the wide end, that is, in the vicinity of the extended position, the cam follower 5a and the rotary cylinder 5 are not integrated with each other. In this state, the first lens group holding member 3 is moved in the optical axis direction and the cam follower 5 is moved. Even if 5a is moved in the cam hole 4a, the rotary cylinder 5 is not rotated only by the movement of the stop mevis 11 along the elongated hole 10a. Note that the transmission control means is constituted by the support member 10 and the retaining screw 11.

Next, the encoder mechanism of the present invention will be described with reference to FIGS. FIG. 2 shows a printed board 35 developed on a plane by brushes 34a, 34b, 34c, 34.
It is the figure shown with d and 34e. FIG. 3 is a diagram showing only the main parts of the driving lens barrel 2 as viewed in the optical axis direction.

As shown in FIG. 2, a conductive pattern is formed on the upper surface of the printed board 35, and brushes 34a, 34b, 34c, 34d, and 34e abut on the conductive pattern. The conductive patterns are different from place to place, and therefore, if the circumferential positions where the brushes abut are different, the four brushes will generate different outputs in total.
As a result, the relative rotational positional relationship between the driving lens barrel 2 and the fixed lens barrel 4 is obtained. The printed board 3
5, a square opening 35a is provided in the vicinity of the lower end surface. When the printed board 35 is mounted on the driving lens barrel 2, the opening 35a is inserted through the projection 2c, and the printing on the driving lens barrel 2 is performed. It provides a reference for positioning the plate 35.

In FIG. 3, the thick portion 33c and the thin portion 33
The brush holder 34 composed of the thick part 34f and the thin part 34g is mounted on the arm part 33b composed of d by an eccentric pin 36 so that the thick part and the thin part are brought into contact with each other. The brush holder 34 includes brushes 34a, 34b, 34c, 34d, 34 of the same shape on the thick portion 34f.
e are juxtaposed and each rear end side is embedded and mounted. Brush 3
The free ends, that is, the distal ends of the 4a, 34b, 34c, 34d, and 34e are arc-shaped, and are in contact with a printed board 35 provided on the drive lens barrel 2.

The eccentric pin 36 has a disk-shaped head 36a,
It is composed of a coaxial disc-shaped body 36b and a cylindrical foot 36c having an axis eccentric to the body 36b. A tool hole (a cross hole in the embodiment) into which a tool (not shown) for rotating the eccentric pin 36 can be inserted is provided on the upper surface of the head 36a. The eccentric pin 36 engages the body portion 36b with the elongated hole 34h of the brush holder 34, and fits the foot portion 36c into the opening 35c of the arm portion 33b.
c is configured to be rotatable with respect to the opening 35c but not to come off. The block 33, the screws 41 and 42, and the arm 33b and the eccentric pin 36 constitute a moving means.

Next, the zoom operation of the zoom lens barrel according to the present invention will be described below with reference to the drawings. For example,
When the first lens unit L1 and the second lens unit L2 are driven from the retracted position shown in FIG. 4 to the extended position shown in FIG. 4, when the gear 20 is rotated by the motor 21 shown in FIG. The transmission is performed, and the drive lens barrel 2 rotates about the optical axis. With this rotation,
The cam follower 3d of the first lens group holding member 3 moves along the cam groove 2d, but moves in the optical axis direction without being rotated around the optical axis, being restricted by the linear groove 4b (in this case, it moves forward). Then, the first lens group holding member 3 is moved or moved forward in the optical axis direction together with the second lens group holding member 6. The movement of the first lens group holding member 3 also causes the rotation cylinder 5 to move.

With the movement of the first lens group holding member 3, the cam follower 5a implanted in the rotary cylinder 5 via the support member 10 moves forward in the cam hole 4a of the fixed cylinder 4, so that the rotary cylinder 5 rotates around the optical axis while moving in the optical axis direction. By this rotation, the cam follower 6a implanted in the second lens group holding member 6 moves along the cam hole 5b, but the rotation is prohibited by the straight groove 3c. Move relative to the first lens group holding member 3 in the direction of the optical axis, whereby the first lens group L
When 1 reaches the extended position, the first lens unit L1
The distance between the lens and the second lens unit L2 changes. This configuration is such that when the first lens unit L1 is moved forward while the second lens unit L2 is fixed, the image plane of the lens that matches the film surface of the camera moves the first lens unit L1. It is intended to prevent the misalignment.

By loosening the stop screw 11 of the support member 10 near the retraction position and moving the first lens group holding member 3 forward, the cam follower 5a moves along the cam hole 4a of the fixed cylinder 4, It turns around the optical axis together with the member 10 around the optical axis. However, stop mebis 11
Since the lens barrel is loose, the rotary cylinder 5 cannot be rotated, so that the second lens group holding member 6 cannot move relative to the first lens group holding member 3 in the optical axis direction. As a result, by rotating the drive lens barrel 2, the lens units L1, L2 are maintained while the distance between the lens units L1 and L2 is kept constant.
Can be moved in the optical axis direction. According to the above-described method, the back adjustment can be performed without inserting a washer between the zoom lens barrel and the camera body.

When the above-described back adjustment is performed, the driving lens barrel 2 rotates with respect to the fixed lens barrel 4, and the output of the encoder mechanism does not indicate an accurate zoom position. To prevent this, the detection origin of the encoder mechanism is adjusted. It is shown below.

In FIG. 1, the screws 41 and 42 for attaching the block 33 are loosened, and the block 33 is moved in the circumferential direction around the optical axis along the elongated hole 33a. As the block 33 moves, the arm 33b also moves in the circumferential direction until it comes into contact with the protrusion 2c. After the arm 33b contacts the projection 2c, the screws 41 and 42 are tightened up. At this point, the rough adjustment of the brush and the printed board is completed.

Next, while rotating the eccentric pin 36 little by little in FIG. 3, the detection origin of the encoder mechanism is searched.
By rotating the eccentric pin 36, the brush holder 3
In the four long holes 34h, the body 36b rotates eccentrically and presses the wall of the long hole 34h. However, the brush holder 34 can move only in the circumferential direction with respect to the arm 33b, and the elongated hole 34h extends in the optical axis direction. The body 34 moves only in the circumferential direction with respect to the arm 33b together with the brush. Therefore, the brush can be moved in the circumferential direction with respect to the printed board 35, and the fine adjustment of the encoder mechanism is performed while observing the output change of the encoder mechanism.

In the zoom lens barrel of the present embodiment, the brush is provided on the fixed barrel side and the printed board is provided on the drive barrel side. However, the brush is provided on the drive barrel side. It is possible to provide a printed board on the fixed lens barrel side. In that case, the moving means is provided on the driving lens barrel side.

[0033]

According to the zoom lens barrel of the present invention described above, one of the drive barrel and the fixed barrel provided with the pattern means is provided with the drive barrel and the fixed mirror. Since the moving means for moving the detecting means provided on the other lens barrel of the cylinder in the rotation direction of the pattern means is provided,
Even if the phases of the fixed lens barrel and the drive lens barrel deviate due to the back adjustment, the detection origin of the encoder mechanism is moved to the original position by moving the detection means in the rotation direction of the pattern means. Can be. Thereby, the output signal of the encoder mechanism with respect to the zoom position of the zoom lens can be accurately matched.

[Brief description of the drawings]

FIG. 1 is a perspective view of a zoom lens barrel according to the present invention.

FIG. 2 shows a brush 34 with a printed board 35 developed on a plane.
The figure shown with a, 34b, 34c, 34d, and 34e.

FIG. 3 is a diagram showing only a main part of the driving lens barrel 2 as viewed in an optical axis direction.

FIG. 4 is a sectional view in the optical axis direction showing the zoom lens barrel when the first and second lens groups are at a wide-angle position (retracted position).

[Description of Signs of Main Parts]

 DESCRIPTION OF SYMBOLS 1 ... Camera 2 ... Driving lens barrel 4 ... Fixed lens barrel 34a, 34b, 34c, 34d, 34e ... Brush 35 ... Printed board

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshio Imura 1-6-3 Nishioi, Shinagawa-ku, Tokyo Nikon Oi Works Co., Ltd. (72) Inventor Noboru Akami 1-3-6 Nishioi, Shinagawa-ku, Tokyo No. Nikon Corporation Oi Works (56) References JP-A-1-207727 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 7/08 G02B 7/04 G02B 7 /Ten

Claims (1)

(57) [Claims] A first lens unit; a second lens unit; a fixed lens barrel; a driving lens barrel which performs a zoom operation by rotating with respect to the fixed lens barrel; and a rotation of the driving lens barrel. Driving force transmitted to the first lens means, and the first lens means is moved in the direction of the optical axis with respect to the film surface of the camera, and driving by rotation of the driving lens barrel Transmitting a force to the second lens means and changing the distance to the first lens means while moving the second lens means in the optical axis direction;
A driving force transmitting means, and a link between the driving lens barrel and the second driving force transmitting means is cut off to stop the driving force transmission, and the first lens means is connected to the second lens means. A transmission control means for integrally moving in the optical axis direction with respect to the film surface; and a transmission control means provided on one of the driving lens barrel and the fixed lens barrel; A pattern means for rotating relative to the other lens barrel together with the one lens barrel; and a pattern means provided on the other lens barrel and reading the pattern means rotated relative to the other lens barrel to read the one mirror. A zoom lens mirror, comprising: a detecting means for detecting a relative rotation amount of the cylinder; and a moving means for moving the detecting means in a direction of relative rotation of the pattern means with respect to the other lens barrel. Tube.