JP2724250B2 - Zoom lens device - 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 apparatus, and more particularly, to a structure of a moving mechanism for moving a lens during zooming.

[0002]

2. Description of the Related Art Recently, a two-group zoom system has been put into practical use.
Zoom lenses have also been incorporated into compact cameras. In such a zoom lens, the front group lens with a focusing mechanism in the variator lens group and the rear group lens with a compensator function that satisfactorily corrects the movement of the focal plane during zooming are simultaneously moved in the optical axis direction. There is provided a camera in which the focal length is changed while changing the focal length. In this zoom lens, if the subject distance is different for a certain zoom position, the amount of movement of the front group lens is different, and if zooming is further performed and the zoom position is changed, for the same subject distance as the previous zoom position, Also, the amount of movement of the front group lens changes. Therefore, such a focus method of the zoom lens is a method in which the in-focus position of the front group lens corresponding to the zoom position and the subject distance is determined and stored in advance or calculated by a calculation.

Incidentally, the focus position of the front group lens stored or calculated as described above becomes an optimum position when the front group and the rear group lens moved during zooming are accurately positioned. For this reason, when moving the zoom lens using a cam mechanism or a helicoid mechanism suitable for mass production, for example, when stopping the lens at an arbitrary zoom position, the lens is always moved from a certain direction and then stopped. With the one-sided drive system, the backlash generated in the moving mechanism is absorbed to accurately position the lens.

[0004]

However, the adoption of the one-sided drive method has a disadvantage that the timing of the operation completion of the variable power operation member and the stop of the moved lens are slightly shifted. Further, in a camera in which a one-side drive motor is linked to a mechanism for changing the finder magnification, the finder magnification tends to fluctuate even after the operation of the zoom operation member is completed, and this tends to give an unstable operation feeling.

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art described above, and provides a zoom lens apparatus which does not employ a one-sided drive system and can absorb backlash generated in a moving mechanism. The purpose is to do.

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a movable lens having a front lens incorporated therein in response to a displacement of a cam surface by rotating a cam cylinder having a cam surface. In a zoom lens in which a cylinder advances and retreats, a rear group lens frame that is provided to the movable cylinder so as to be able to advance and retreat and holds a rear group lens, abuts on the rear group lens frame, and rotates together with the cam cylinder to rotate. A cam member for moving the rear lens unit in the optical axis direction, a moving member for contacting the cam member, and moving the cam member in the optical axis direction by a predetermined amount when the rotation direction of the cam barrel is switched; Biasing means for biasing the rear lens group toward the moving member.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a zoom lens apparatus according to the present invention comprises a fixed barrel 10 formed integrally with a camera body, a cam barrel 11 and a cam retainer 12 provided inside the fixed barrel 10. The cam barrel 11 and the movable cylinder 13 provided inside the cam retainer 12 are provided, and the external appearance of the cam cylinder 11, the cam retainer 12, and the movable cylinder 13 is as shown in FIG.

[0008] The cam cylinder 11 has a male helicoid 1 screwed to a female helicoid 10a provided on the inner peripheral surface of the fixed cylinder 10.
1a and the gear part 11b are integrally formed. The drive of the zoom motor 15 is transmitted to the gear portion 11b.
By this driving, the cam cylinder 11 rotates between the wide position and the tele position, and moves forward and backward in the optical axis direction according to the lead of the male helicoid 11a. 3 is provided on the inner peripheral surface of the cam cylinder 11.
As shown in the figure, three cam surfaces 11c for moving the moving barrel 13 in the optical axis direction and a rear group moving groove 11d provided in parallel with the optical axis for moving the rear lens in the moving barrel 13 are integrated. Is formed. After this, both walls 1 of the group moving groove 11d
Reference numerals 1e and 11f denote a tele-direction contact wall 11e that comes into contact with a later-described reaction pin 27c and an adjustment pin 29c when the cam cylinder 11 rotates in the tele position direction, and when the cam cylinder 11 rotates in the wide position direction. Response pin 27c and adjustment pin 2
9c.

The movable cylinder 13 is provided with three cam follower pins 13a on its outer periphery, and is inserted into the cam cylinder 11 so that these cam follower pins 13a abut on the cam surface 11c. After that, cam holder 1
When the cam follower 2 is inserted into the cam cylinder 11, the cam follower pin 13a is sandwiched between the cam surface 11c and the front end of the cam retainer 12. The rear end of the cam retainer 12 is engaged with the cam cylinder 11 via a spring 17. This spring 17 is connected to the cam follower pin 13a.
In the direction of the cam surface 11c. Thus, when the cam barrel 11 is rotated by the driving of the zoom motor 15, the movable barrel 13 moves forward and backward in the optical axis direction according to the rotation of the cam surface 11c. This reciprocation advances and retreats linearly according to a rectilinear guide 10a provided on the fixed frame 10.

Inside the movable barrel 13, a front group lens 20 having a variator lens with a focusing mechanism and a rear group lens 21 having a compensator function are built. The front lens group 20 is screwed with the movable barrel 13 via a helicoid mechanism. At the time of focusing, the focusing motor is driven by the focusing motor to advance and retreat in the optical axis direction according to the helicoid lead.
At the time of zooming, it moves together with the movement of the movable barrel 13.

As shown in FIG. 4, a spring 25, a rear lens frame 26, a cam member 27, a cam inscribed member 28, a cam responsive member 29, and a fixed member 30 are incorporated in the rear end side of the movable cylinder 13 in this order. It is. The rear lens group frame 26 is provided with three ribs 26a on the outer periphery thereof, and these ribs 26a
Guide groove 1 provided on the inner surface of the movable cylinder 13 in parallel with the optical axis.
3b, it is incorporated so as to be able to advance and retreat along the guide groove 13b.

The cam member 27 integrally has three rear group lens advancing / retreating cam surfaces 27a on the front end side and a tracking adjustment cam surface 27b provided on the opposite side of the rear group lens advancing / retreating cam surface 27a. The rib 26a is in contact with the rear group lens advance / retreat cam surface 27a. The cam member 27 is mounted on the movable barrel 13 and then, via a relief hole 13c provided in the movable barrel 13, a response pin 27c.
The response pin 27c projects from the escape hole 13c and fits in the rear group movement groove 11d. When the cam cylinder 11 rotates, the cam member 27 rotates integrally with the rotation, and the rear lens group frame 26 advances and retreats according to the rotation of the cam surface 27a. The tracking-adjusting cam surface 27b has a shape that is linearly inclined, and the inclination is inclined in a direction opposite to the inclination of the cam surface 27a.

The cam inscribed member 28 has three contact ribs 28 at its front end, which are in contact with the tracking adjustment cam surface 27b.
a is provided, and is rotatably incorporated in the movable barrel 13. The cam inscribed member 28 is provided with a long hole 2 provided therein.
The rear group adjusting member 29 is fixed to the rear group adjusting member 29 with an adjusting screw 29b via 9a. On the outer peripheral surface of the rear group adjusting member 29, the moving cylinder 13 is provided.
The rear group moving groove 1 protruding from the escape groove 13d provided in the
An adjustment pin 29c intervening in 1d is fixed.

By the rotation of the cam cylinder 11, the adjusting pin 29c is moved to both the walls 11e, 11d of the rear group moving groove 11d.
f, the rear group adjusting member 29 rotates together with the cam member 27. The diameter of the adjustment pin 29c is smaller than the diameter of the response pin 27c. For this reason, when the rotation direction of the cam cylinder 11 is switched, there is a case where the adjusting pin 29c does not contact either of the two walls 11e and 11f of the rear group moving groove 11d. At this time, since the rear group adjustment member 29 does not rotate but only the cam member 27 rotates, the contact position between the contact rib 28a and the tracking adjustment cam surface 27b is shifted, and the contact position is Cam member 27
Is moved in the optical axis direction while rotating.

Finally, when the fixing member 30 is fixed to the movable barrel 13, the spring 25 urges the rear lens frame 25 in the movable barrel 13 toward the rear group adjusting member 29, and the assembly of the movable barrel 13 is completed. .

When assembling such a zoom lens device, after adjusting the optical axis of the zoom lens, the cam barrel 1 is adjusted.
1 is rotated to the wide position or the tele position, and the position of the rear group lens 21 with respect to the front group lens 20 is determined. Such positioning of the rear group lens 21 is referred to as tracking adjustment. In the tracking adjustment in the present embodiment, the above-described adjustment screw 29b is loosened and the cam inscribed member 28 is rotated within the range of the elongated hole 29a. . By this rotation, the contact position between the contact rib 28a and the tracking adjustment cam surface 27b at the time of the wide position or the tele position is determined, and the rear group lens frame 27 is positioned with respect to the front group lens 20. Since the rear group lens advancing / retreating cam surface 27a and the tracking adjustment cam surface 27b provided on the cam member 25 are inclined in opposite directions, the rear group lens frame with respect to the rotation of the cam inscribed member 28. 26 can be moved over a wide range.

Next, the advancing and retreating of the front lens group 20 in the above-described zoom lens device will be briefly described. First, when the zoom motor 15 is driven, the cam barrel 11 rotates with respect to the fixed barrel 10 by this drive, and the rotation of the cam surface 11c causes the movable barrel 13 to advance and retreat in the optical axis direction. The front lens group 20 also moves together with the movement of the movable barrel 13. FIG. 5 is a graph showing such a movement of the front group lens 20 with respect to the rotational position of the cam barrel 11 and the distance from the image forming plane.

As shown in FIG. 5, the distance from the imaging plane of the front lens group 20 to the rotational position of the cam barrel 11 is
Are different from each other when they are rotated from the wide position toward the telephoto position and stopped, and when they are rotated and stopped in the opposite direction. This is because the rotational position of the cam cylinder 11 shown in the figure is represented by Y and Z, that is, the play generated in the fixed cylinder 10, the cam cylinder 11, and the movable cylinder 13 when the rotation of the cam cylinder 11 is switched. This is because the front group lens 20 does not move with respect to the rotation of the cam barrel 11 by an amount. If zooming is performed as it is, the distance between the front group lens 20 and the rear group lens 21 varies depending on the rotational position of the cam barrel 11 and focuses. Misalignment occurs. In order to prevent this, the movement of the rear group lens 21 is corrected as shown in the figure according to the displacement of the front group lens 20 with respect to the rotational position of the cam cylinder 11.

Next, the movement of the rear lens group 21 will be briefly described. FIG. 6 shows the state of the response pin 27c and the adjustment pin 29c intervening in the rear group movement groove 11d when the cam cylinder 11 is in the wide position.
As shown in FIG. 6, both walls 11e, 11 of the rear group moving groove 11d are formed.
The interval of f is the same as the diameter of the response pin 27c, and is the sum of the diameter and the gap L of the adjustment pin 29c. When the cam cylinder 11 is rotated in the tele-direction from this state, the tele-direction contact wall 1 shown in FIG.
1e moves downward. Thereby, the response pin 2
Since the member 7c rotates, the cam member 27 rotates. At this point, since the telescopic contact wall 11e has not yet contacted the adjustment pin 29, the cam inscribed member 28 has not been rotated.

Therefore, the movement of the rear lens frame 26 is
By the rotation of the cam member 27 alone, the cam member 27 is moved by a combined displacement of the tracking adjustment cam surface 27b and the rear group lens advance / retreat cam surface 27a. That is, the rear group lens frame 26 is moved by rotating only the cam member 27 and the tracking adjustment cam surface 27 b and the contact rib 28 of the rear group adjustment member 29.
The rear group lens frame 2 is moved by an amount corresponding to the displacement of the cam member 27 in the optical axis direction by an amount corresponding to the displacement of the contact position between the rear group lens frame 2 and the contact position between the rear group lens advance / retreat cam surface 27a and the contact rib 28a.
7 is added to the amount of movement. Such movement of the rear lens group 21 corresponds to a straight line shown between the rotational position of the cam barrel 11 shown in FIG. 5 and the position rotated by Y from the wide position to the tele position direction.

Thereafter, when the cam cylinder 11 reaches a position rotated by Y from the wide position, that is, when the tele-direction contact wall 11e shown in FIG.
9c, whereby the rear group adjusting member 29 rotates. Further, when the rotation of the cam cylinder 11 is performed, the cam member 27 and the rear group adjusting member 29 rotate together in accordance with the rotation, so that the movement of the rear group lens frame 26 is performed by the rear group lens advancing / retreating cam surface 27a. It moves by the displacement of.

When the rotation position of the cam barrel 11 reaches the telephoto position, the state of the response pin 27c and the adjustment pin 29c intervening in the rear group movement groove 11d is as shown in FIG. When the cam cylinder 11 is rotated in the wide position direction from this state, the wide direction contact wall 11f shown in FIG.
Moves upward. In response to this, the response pin 27c
However, the cam member 27 rotates in a direction opposite to the above-described rotation. At this time, the rear lens group frame 26
Is moved in a direction opposite to the above-described movement by the combined displacement of the tracking adjustment cam surface 27b and the rear group lens advance / retreat cam surface 27a by the rotation of the cam member 27 alone. The rotation position of the cam cylinder 11 shown in FIG. 5 corresponds to a straight line shown between the tele position and the position rotated in the wide position direction by Z from this position.

Thereafter, when the wide-direction abutment wall 11e rotates by L from the state shown in FIG. 7, the cam cylinder 11 abuts on the adjustment pin 29c.
Rotates. Therefore, since the cam member 27 and the rear group adjusting member 29 rotate in response to the rotation of the cam cylinder 11, the movement of the rear group lens frame 26 moves the rear group lens advance / retreat cam surface 27a.
It moves only by the displacement of.

As described above, in this embodiment, the cam cylinder 11
The movement of the rear group lens 21 with respect to the rotation position of the front group lens 20 with respect to the rotation position of the cam barrel 11 as shown in FIG.
The distance between them is corrected in accordance with the movement of the camera, thereby preventing a focus shift during zooming.

[0025]

As described above, the zoom lens apparatus according to the present invention is provided with the moving member for moving the cam member in the optical axis direction by a predetermined amount when the rotating direction of the cam barrel is switched. By correcting the distance between the front lens group and the rear lens group, the focusing accuracy of the lens during zooming can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a zoom lens device according to the present invention.

FIG. 2 is an exploded perspective view of a main part of a cam barrel in the zoom lens device.

FIG. 3 is a development view showing an inner surface of the cam cylinder.

FIG. 4 is an exploded perspective view of a main part of a moving cylinder in the zoom lens device.

FIG. 5 is a graph showing movement of a front lens group and a rear lens group.

FIG. 6 is an explanatory diagram showing a state of a rear group moving groove when the rotation position of the cam barrel is a wide position.

FIG. 7 is an explanatory diagram showing a state of a rear group moving groove when the rotation position of the cam barrel is rotated from a wide position.

FIG. 8 is an explanatory diagram showing a state of a rear group moving groove when the rotation position of the cam barrel is at the tele position.

[Explanation of symbols]

 Reference Signs List 10 fixed cylinder 11 cam cylinder 11c cam surface 11d rear group moving groove 11e wide direction contact wall 11f tele direction contact wall 13 moving cylinder 20 front group lens 21 rear group lens 26 rear group lens frame 27 cam member 27a rear group Cam surface for lens advance / retreat 27b Cam surface for tracking adjustment

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kiyotaka Kobayashi 2-26-30 Nishiazabu, Minato-ku, Tokyo Fuji Photo Film Co., Ltd. (56) References JP-A-2-89012 (JP, A) JP-A-2 -130512 (JP, A)

Claims (1)

(57) [Claims] 1. A zoom lens in which a movable cylinder incorporating a front lens group moves forward and backward in response to a displacement of the cam surface by rotating a cam cylinder having a cam surface formed therein. A rear group lens frame provided for holding the rear group lens, a cam member that abuts on the rear group lens frame, rotates integrally with the cam barrel, and advances and retreats the rear group lens in the optical axis direction; A moving member that contacts the cam member and moves the cam member by a predetermined amount in the optical axis direction when the rotation direction of the cam cylinder is switched; and a biasing member that biases the rear group lens toward the moving member. A zoom lens device comprising: