JPH06300956A - Zoom lens barrel - Google Patents

Abstract

PURPOSE:To provide a zoom lens barrel in which back adjustment is easily performed and whose assembling workability is improved. CONSTITUTION:Since a moving means for moving a detection means provided on either of a driving lens barrel 2 and a fixed lens barrel 4 to the other of the driving lens barrel 2 and the fixed lens barrel 4, where a pattern means is provided, in the rotating direction of the pattern means is provided, the detection origin of an encoder mechanism is moved to an initial place by moving the detection means in the rotating direction of the pattern means even when a phase is deviated between the lens barrels 4 and 3 because of the back adjustment. Thus, an output signal from the encoder mechanism for the zoom position of a zoom lens is accurately made coincident.

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, a rotation of a driving lens barrel and a focal length of a zoom lens correspond to each other. Providing a printed board on which different patterns are formed depending on the position, a brush that contacts the printed board is hung from a fixed lens barrel, and an encoder mechanism that reads the pattern after rotational movement with the brush and outputs it as a rotation amount, that is, a focal length is provided. Zoom lens barrels are already known.

By the way, in the conventional zoom lens barrel, since the lens group is composed of a plurality of groups (for example, two groups), the focal length changes with the zoom operation. In order to always match the focal length with the film surface of the camera, the mutual distance of each lens group is changed in a predetermined relationship with the film surface of the camera. However, with this configuration, one of the lens groups cannot be moved independently, so back adjustment at the time of assembly, that is, work of aligning the image surface of the zoom lens and the print surface of the camera, is performed with the fixed lens barrel of the zoom lens and the camera body. This is done by sandwiching washers with different thicknesses from the (mounting surface) and maintaining an appropriate interval between them. However, this back adjustment requires removal of the zoom lens barrel from the camera each time the washer is inserted, which results in poor workability.

On the other hand, in some types of zoom lens barrels, back adjustment is not performed by inserting a washer between the fixed lens barrel and the camera body, but instead the lens group is formed by rotating the drive lens barrel. The back adjustment can be performed by providing a switching unit that integrally moves in the optical axis direction and operating the switching unit to rotate the drive lens barrel with respect to the fixed lens barrel. According to this back adjustment, workability during assembly can be significantly improved.

[0005]

However, in the case where the zoom lens barrel has the encoder mechanism as described above, the drive barrel relative to the fixed barrel is rotated by rotating the drive barrel for back adjustment. The phase of the cylinder, that is, the detection origin (point of zero rotation amount) of the encoder mechanism is deviated, and as a result, 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 which is easy to perform back adjustment and has improved assembling workability.

[0007]

A zoom lens barrel according to the present invention comprises a first lens means (3, L1), a second lens means (6, L2), and a fixed lens barrel (4). A drive lens barrel (2) that performs a zoom operation by rotationally moving with respect to the fixed lens barrel (4), and a driving force due to the rotation of the drive lens barrel (2) is applied to the first lens means (3, L1). Driving force transmitting means (3d, 2d) for moving the first lens means (3, L1) in the optical axis direction with respect to the film surface of the camera (1), and the driving lens barrel ( The driving force generated by the rotation of 2) is transmitted to the second lens means (6, L2) and the distance to the first lens means (3, L1) is changed, while the second lens means (6) is changed. , L2) to move in the optical axis direction, second drive force transmitting means (5d, 6a), the drive barrel (4) and the second drive force transmitting means (5d, 6a). Driving force transmitting means (5d, 6a)
And disconnecting the driving force transmission to disconnect the first
The lens means (3, L1) of the second lens means (6,
L2) and a transmission control means (10, 11) that is movable with respect to the film surface in the optical axis direction,
One of the drive lens barrel (2) and the fixed lens barrel (4) is provided, and one of the drive lens barrel (2) and the fixed lens barrel (4) is provided with respect to the other lens barrel. The pattern means (35) that moves relative to the lens barrel and the other lens barrel are provided, and the relative rotation amount of the one lens barrel is detected by reading the relatively rotated pattern means (35). Detecting means (34a, 34b, 34c, 34d, 34e) for performing the detecting means and the pattern means (3) for the other lens barrel.
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 lens barrel and the fixed lens barrel provided with the pattern means is opposite to the other of the driving lens barrel and the fixed lens barrel. Since the moving means for moving the detecting means provided on the cylinder in the rotation direction of the pattern means is provided, even if the fixed lens barrel and the drive lens barrel are out of phase by back adjustment,
By moving the detecting means in the rotating direction of the pattern means, the detection origin of the encoder mechanism can be moved to the original position. As a result, the output signal of the encoder mechanism can be accurately matched with the zoom position of the zoom lens.

[0009]

Embodiments of the present invention will now be described 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 driving barrel 2 having a tubular shape is coaxially rotatable inside a fixed barrel 4 having a tubular shape attached to a camera 1, only a part of which is 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.

An annular gear 2b is formed on the outer periphery of the drive lens barrel 2, and the gear 2b is engaged with the gear 20 of the gear train 22. The gear train 22 transmits the rotation of the motor 21 attached to the camera 1. Therefore, the rotation of the motor 21 causes the drive barrel 2 to rotate.

A part of the outer circumference 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 an elongated hole 33a extending in the circumferential direction is screwed and attached onto the shelf 4d by two screws 41 and 42 through the elongated hole 33a. The block 33 is provided with an arm portion 33b extending in the optical axis direction, and the arm portion 33b is provided with an opening 33c (FIG. 3). Further, the arm portion 33b has its upper side portion brought into contact with the protrusion 2c provided on the outer periphery of the drive lens barrel 2.

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

The brush holder 34 extends 5 in the circumferential direction.
Book metal brushes 34a, 34b, 34c, 34d,
34e is attached. The tip of the brush is the drive barrel 2
The printed board 35 attached to the outer periphery of the board by a method such as adhesion
, And its rear end is connected to the CPU (not shown) of the camera body by wiring (not shown). In addition,
The printed board 35 constitutes pattern means, and the brush 34
The detectors a, 34b, 34c, 34d, and 34e form a detector. The encoder mechanism is composed of a printed board 35 and brushes 34a, 34b, 34c, 34d and 34e. The configurations of the arm portion 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 contents 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 in the wide-angle position (retracting position).

The substantially cylindrical fixed lens barrel 4 fixed to the camera 1 side is provided with a straight groove 4b in the optical axis direction on its peripheral wall. Further, on the outer periphery of the fixed lens barrel 4, there is a cylindrical driving lens barrel 2
Although it is rotatable about the optical axis with respect to the fixed lens barrel 4, it is fitted so as not to move in the optical axis direction. A cam groove 2d is formed on the peripheral wall of the drive 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 drive barrel 2, and the gear 20 driven by the motor 21 of FIG. 1 and the gear 2b mesh with each other. Therefore, when the gear 20 is rotated by the motor, the drive lens barrel 2 which is the drive means is rotated.

A first lens group holding member 3 is provided inside the fixed barrel 4 so as to be movable in the optical axis direction. The first lens group holding member 3 has a structure in which an annular portion 3f is connected to the outer circumference of a circular tube portion 3e extending in the optical axis direction.
Further, a partial circular pipe portion 3g is attached to a part of the outer circumference of the annular portion 3f in parallel with the circular pipe portion 3e, and the outer peripheral surfaces of the annular portion 3e and the partial circular pipe portion 3g are fixed to the fixed barrel 4. It is abuttable and slidable. The first lens means L1 and the first lens group holding member 3 form a first lens means.

In the cam groove 2d of the driving lens barrel 2 and the straight-moving groove 4b of the fixed lens barrel 4, the partial circular tube portion 3g of the first lens group holding member 3 holding the first lens group L1 is planted. The cam follower 3d is inserted in the radial direction. Therefore, the first
The lens group holding member 3 does not rotate in the optical axis direction as the drive barrel 2 rotates around the optical axis, but slides forward and backward in the optical axis direction. Further, 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 a first driving force transmission means.

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

A second lens group holding member 6 for holding the second lens group L2 is provided on the inner circumference of the first lens group holding member 3.
Is slidably fitted in the optical axis direction. A cylindrical cam follower 6b is radially planted on the outer periphery of the second lens group holding member 6. The cam follower 6b is inserted through the cam hole 3c and the cam hole 5b. The second lens unit and the second lens unit holding member 6 constitute a second lens unit, and the cam hole 5b and the cam follower 6a form a second lens unit.
It constitutes the driving force transmitting means.

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

By loosening the screw 11 at the wide end, that is, near the feeding position, the cam follower 5a and the rotary cylinder 5 are no longer integrated, and in this state, the first lens group holding member 3 is moved in the optical axis direction to move the cam follower. Even if 5a is moved in the cam hole 4a, the rotating cylinder 5 is prevented from rotating only by moving the stop mebis 11 along the elongated hole 10a. In addition, the support member 10 and the stop screw 11 constitute a transmission control means.

Next, the encoder mechanism of the present invention will be described with reference to FIGS. FIG. 2 shows the printed board 35 developed on a plane as brushes 34a, 34b, 34c, 34.
It is the figure shown with d and 34e. FIG. 3 is a view showing only the main part of the drive lens barrel 2 when 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 are in contact therewith. The conductive patterns are different from place to place, so that if the circumferential positions of the brushes are different, the four brushes will generate different outputs as a whole.
As a result, the relative rotational positional relationship between the drive 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 face in FIG. 2, but when the printed board 35 is mounted on the drive lens barrel 2, the opening 35a is inserted into the protrusion 2c, and the print on the drive lens barrel 2 is performed. It provides a positioning reference for the plate 35.

In FIG. 3, a thick portion 33c and a thin portion 33
A brush holder 34 including a thick portion 34f and a thin portion 34g is mounted on the arm portion 33b including the d portion by an eccentric pin 36 so that the thick portion and the thin portion contact each other. The brush holder 34 has 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 attached. Brush 3
The free ends of 4a, 34b, 34c, 34d, and 34e, that is, the ends are arcuate and are in contact with the printed board 35 provided on the drive barrel 2.

The eccentric pin 36 has a disk-shaped head 36a,
It has a disk-shaped body portion 36b coaxial with it and a cylindrical foot portion 36c having an eccentric axis with respect to the body portion 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 portion 36a. The eccentric pin 36 engages the body portion 36b with the elongated hole 34h of the brush holder 34, and the foot portion 36c is fitted into the opening 35c of the arm portion 33b.
Although c is rotatable with respect to the opening 35c, it does not come off. The block 33, the screws 41 and 42, the arm portion 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 group L1 and the second lens group L2 are driven from the retracted position to the retracted position shown in FIG. 4, when the gear 20 is rotated by the motor 21 of FIG. 1, a rotational force is applied from the gear 20 to the gear 2b. This is transmitted, 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 is restricted by the linear groove 4b and moves in the optical axis direction without rotating around the optical axis (in this case, it moves forward). ), The first lens group holding member 3 is moved or moved forward along with the second lens group holding member 6 in the optical axis direction. The movement of the first lens group holding member 3 also causes the movement of the rotary cylinder 5.

As the first lens group holding member 3 moves, the cam follower 5a implanted in the rotary barrel 5 via the support member 10 moves forward in the cam hole 4a of the fixed barrel 4, so that the rotary barrel Reference numeral 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 linear groove 3c. , Relative to the first lens group holding member 3 in the optical axis direction, whereby the first lens group L
When 1 reaches the extended position, the first lens unit L1
And the lens distance between the second lens unit L2 and the second lens unit L2 changes. In this structure, when the first lens unit L1 is moved forward while the second lens unit L2 is fixed, the image plane of the lens which is aligned with the film surface of the camera is moved by the first lens unit L1. It is to prevent it from shifting together.

By the way, by loosening the stop screw 11 of the support member 10 near the retracted position and advancing the first lens group holding member 3, the cam follower 5a moves along the cam hole 4a of the fixed barrel 4, It rolls around the optical axis together with the member 10 around the optical axis. However, stop mebis 11
Since the lens barrel is loose, the rotating barrel 5 cannot be rotated, and 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 driving lens barrel 2, the lens groups L1 and L2 are kept constant while keeping the distance between the lens groups L1 and L2 constant.
Can be moved in the optical axis direction. According to the above method, back adjustment can be performed without inserting a washer between the zoom lens barrel and the camera body.

By the way, when the above-mentioned back adjustment is performed, the drive lens barrel 2 rotates with respect to the fixed lens barrel 4, and the output of the encoder mechanism does not show 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 to which the block 33 is attached are loosened to move the block 33 in the circumferential direction around the optical axis along the elongated hole 33a. As the block 33 moves, the arm portion 33b also moves in the circumferential direction until it comes into contact with the protrusion 2c. After the arm portion 33b contacts the protrusion 2c, the screws 41 and 42 are tightened. At this point, the rough adjustment between the brush and the printed board is completed.

Next, in FIG. 3, the detection origin of the encoder mechanism is searched while rotating the eccentric pin 36 little by little.
By rotating the eccentric pin 36, the brush holder 3
In the elongated hole 34h of No. 4, the body portion 36b eccentrically rotates and presses the wall portion of the elongated hole 34h. However, since the brush holder 34 is configured to be movable only in the circumferential direction with respect to the arm portion 33b, and the long hole 34h extends in the optical axis direction, the brush holder 34 is eccentrically rotated to hold the brush holder 34b. The body 34 moves only in the circumferential direction with respect to the arm portion 33b together with the brush. Therefore, the brush can be moved in the circumferential direction with respect to the printed board 35, and the encoder mechanism can be finely adjusted while observing the output change of the encoder mechanism.

In the zoom lens barrel of this embodiment described above, the brush is provided on the fixed barrel side and the printed board is provided on the drive barrel side, but the brush is provided on the drive barrel side. It is possible to provide the printed board on the fixed lens barrel side. In that case, the moving means is provided on the side of the drive lens barrel.

[0033]

According to the zoom lens barrel of the present invention described above, the drive barrel and the fixed mirror are provided with respect to one of the drive barrel and the fixed barrel provided with the pattern means. Since the moving means for moving the detecting means provided on the other lens barrel of the barrel in the rotation direction of the pattern means is provided,
Even if the fixed lens barrel and the drive lens barrel are out of phase due to 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. You can As a result, the output signal of the encoder mechanism can be accurately matched with the zoom position of the zoom lens.

[Brief description of drawings]

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

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

FIG. 3 is a view showing only a main part of the drive lens barrel 2 as viewed in the 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 the wide-angle position (retracting position).

[Explanation of symbols for main parts]

 1 ... Camera 2 ... Drive lens barrel 4 ... Fixed lens barrel 34a, 34b, 34c, 34d, 34e ... Brush 35 ... Printed board

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoshio Imura 1-6-3 Nishioi, Shinagawa-ku, Tokyo Inside Nikon Oi Manufacturing Co., Ltd. (72) Inventor Noboru Akami 1-3-6 Nishioi, Shinagawa-ku, Tokyo Nikon Oi Manufacturing Co., Ltd.

Claims (1)

[Claims] 1. A first lens means, a second lens means, a fixed lens barrel, a drive lens barrel that performs a zoom operation by rotationally moving with respect to the fixed lens barrel, and a rotation of the drive lens barrel. Driving force transmitting means for transmitting the driving force to the first lens means to move the first lens means in the optical axis direction with respect to the film surface of the camera, and driving by rotation of the driving lens barrel. A second force for transmitting the force to the second lens means and moving the second lens means in the optical axis direction while changing the distance to the first lens means;
Of the driving force transmitting means, and the driving lens barrel and the second driving force transmitting means are cut off from each other to stop the driving force transmission, and the first lens means is changed to the second lens means. A transmission control unit that is integrally movable in the optical axis direction with respect to the film surface, and is provided on one of the drive lens barrel and the fixed lens barrel, and the drive lens barrel and the fixed lens barrel are fixed. A pattern unit that moves relative to the other barrel of the lens barrel relative to the other barrel, and a pattern unit that is provided on the other barrel and reads the pattern unit that has rotated relative to the other barrel. A zoom lens mirror characterized in that a detection means for detecting the relative rotation amount of the cylinder and a moving means for moving the detection means in the relative rotation direction of the pattern means are provided with respect to the other lens barrel. Cylinder.