JPH03248110A - Zoom lens driving mechanism - Google Patents

Abstract

PURPOSE:To reduce the size and cost of a lens barrel by providing a member integrally with a cam which is so shaped as to stop a specific lens group at plural positions in the direction of the optical axis and a cam which is so shaped as to adjust the focus by moving a corresponding lens group. CONSTITUTION:An annular cam 2 in a cylindrical shape is provided with the 1st groove cam 2a which is so shaped as to adjust the focus of the lens group, the 2nd groove cam 2b which is so shaped as to stop the lens group at the positions in the cam shape, and a driven gear 2c, and is fitted rotatably onto the outer periphery of a fixed frame 1. Then the ring is positioned in the direction of the optical axis O with a stopper ring 15, etc. The annular cam 2 for lens driving is integrated, the driving mechanism for the lens group for focus adjustment is simplified, and only one driving system such as a driving motor is required. Consequently, the mechanism can be made compact and reduced in cost.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention has a zoom lens drive mechanism, specifically a plurality of lens groups that are movable for zooming, and furthermore, a zoom lens drive mechanism that includes a plurality of lens groups that are movable for zooming. The present invention relates to a drive mechanism for a lens group of a zoom lens barrel that moves for focusing in response to movement of other lens groups.

[Prior Art] In the conventional zoom lens barrel of the above type,
-As for the directional structure, the two shown in Figure 4 are
There is a group zoom lens barrel. The lens group of this zoom lens barrel is composed of a second lens group 31 that is driven only during a zooming operation, and a first lens group 30 that is driven during both zooming and focusing operations. The drive system includes a zooming operation drive system and a focusing drive system.

Furthermore, in the zoom lens system disclosed in Japanese Patent Application Laid-open No. 54-39144, a correction lens group is driven relative to a variable power lens group in a zoom lens system that performs zooming while maintaining a focused state by a focusing means. By making a predetermined movement different from that during normal zooming, it is possible to perform constant magnification photography regardless of the distance of the subject.

[Problems to be Solved by the Invention] However, the conventional zoom lens barrel described above has two drive systems, a zoom system and a focus system, and not only requires two drive sources, but also a drive system. The mechanism itself was extremely complex.

Therefore, the structure of the above-mentioned zoom lens barrel having a conventional general structure will be explained in detail using FIG.
A first group lens 30 of a concave lens system is held by a first group lens frame 25 screwed onto a helicoid frame 24, and the helicoid frame 24 is rotatably supported by a movable frame 23. The movable frame 23 is slidably inserted into the inner peripheral portion of the fixed frame 21. The fixed frame 21 is connected to an optical low-pass filter 34 on the optical axis O. It holds an image sensor CCD 32 and the like arranged in the imaging section via an infrared cut filter 35. Note that the CCD 32 is fixed by a support frame 33. Further, the helicoid frame 24 is rotated by a focus motor (not shown) via a gear 36 to drive the first group lens frame 25 for focusing. The lens frame 25 is mounted on an arm 25 so as to be guided straightly relative to the movable frame 23.
a is inserted into the straight groove 23a of the moving frame 23. On the other hand, the second group lens 31 of the convex lens system is held by a second group lens frame 26 that is slidably inserted into the inner peripheral portion of the fixed frame 21 .

Driving bins 27 and 28 are fixed to the moving frame 23 and the second group lens frame 26, respectively.
are guided in a straight line by the straight guide groove 21a of the fixed frame 21, and the first and second group groove cams 22a, 2 of the zoom cam ring 22 are rotatably fitted into the outer circumference of the fixed frame 21.
2b. The cam ring 22 is connected to a zoom motor (
(not shown) via a gear train (not shown) and a drive gear 37.

The operation of this zoom lens barrel configured as above is as follows.
First, when the cam ring 22 is rotated by the zoom motor, the shapes of the first and second group groove cams 22a and 2.2b shown in the developed view of the cam ring 22 in FIG. ), move each frame 23. above to the position corresponding to Tele (T).
26 moves and zooming is performed. Further, in order to perform a focusing operation in response to the movement of the frame 26, the helicoid frame 24 is rotated by the focus motor, and the first
The group lens frame 25 is driven to the in-focus position, and focusing is completed.

As described above, in the conventional zoom lens barrel, the drive mechanism on the side of the first group lens that performs focusing has a frame portion that has a multilayer structure because the zoom operation and the focusing operation are superimposed. Furthermore, there are two drive systems, and two drive sources, a zoom motor and a focus motor, are required as drive actuators. Therefore,
Since the frame structure becomes larger and space is required for the arrangement of the drive motor, etc., it is unavoidable that the lens barrel becomes larger. Furthermore, the number of constituent parts increases and the product cost also increases.

In order to solve the above-mentioned problems, an object of the present invention is to provide a plurality of cams that drive a plurality of lens groups in one member, and provide a drive body stopper part on one of the drive cams, so that the drive body can be stopped while the cam is not in use. To provide a zoom lens drive mechanism that allows a lens drive system to be simplified, a lens barrel to be smaller, and cost to be lowered by moving a lens group to adjust the focus.

[Means and effects for solving the problem] The zoom lens drive mechanism of the present invention is a zoom lens drive mechanism that drives a zoom lens having a predetermined lens group and a lens movable corresponding to this lens group. , a cam having a shape for stopping the predetermined lens group at a plurality of positions with respect to the optical axis direction; and a cam having a shape that allows focus adjustment by moving the corresponding lens group while the predetermined lens group is at rest. The present zoom lens drive mechanism is characterized in that a plurality of cams are provided in an integral member, and the present zoom lens drive mechanism drives a lens group for zooming and focusing operations by driving a member in which the plurality of cams are integrally provided. This makes it possible to perform the movement of

[Implementation example] The present invention will be described below based on illustrated embodiments.

FIG. 1 shows a longitudinal sectional view of a main part of a zoom lens barrel to which a zoom lens drive mechanism according to an embodiment of the present invention is applied.

Moreover, FIG. 2 shows a perspective view of the main parts of the zoom lens barrel. As shown in FIG. 1, the present zoom lens barrel including the imaging section is composed of a fixed frame section, a cam ring 2, two lens frame sections, and the cam active drive system.

The fixed frame portion includes a fixed frame 1 having a cylindrical lens frame sliding portion and a linear guide groove 1a on the inner circumference of the cylinder, and an optical LPF ( A low-pass filter) 16, an infrared cut filter 17, and a CCD 12 which is a solid-state image sensor supported by a mounting frame 13. In addition, the cylindrical cam ring 2 is
The first lens group has a focus adjustable shape.
A grooved cam 2a, a second grooved cam 2b having a shape that allows the cam to rest at a plurality of positions, and a driven gear 2.
C is provided. Then, it is rotatably inserted into the outer periphery of the fixed frame 1. Positioning in the direction of the optical axis O is performed by a retaining ring 15 or the like.

The lens frame section includes a first group lens frame 3 that holds a first group lens 10 that has a variator focus function, is movable in correspondence with the second group lens, and is also driven during focusing; A second group lens 11 which is a lens group having the function of a convencator/relay lens and which is extended in a predetermined manner in response to a zoom operation.
and a second group lens frame 4 that holds the fixed frame 1, each of which is slidably fitted into the inner circumference of the fixed frame 1. The first and second drive bins 5 installed in the first and second lens frames 3 and 4
．． 6 is slidably inserted into the linear guide groove 1a of the fixed frame 1, and is also slidably inserted into the first and second grooves 2g and 2b of the cam ring 2, respectively.

As shown in FIG. 2, the cam drive system includes a focus/zoom drive motor 7 supported by a fixed frame 1, its output gear 8, and a driven gear of the cam ring 2 that meshes with the output gear 8. Gear trains 9a, 9b, 9c rotating 20
Consisted of.

The 1.2nd lens frame 3.4 has a 1.2nd groove cam 2a,
The grooved cam shape is shown in FIG. 3, and the grooved cam shape is shown in FIG.

The second grooved cam 2b for driving the second lens frame 4 has a shape for stopping the rotation of the cam ring 2 at three locations, that is,
Region R of the shape where the lead angle O of the cam is not extended
lol.

It has R8, RT. The cam positions W, S, and T in these areas give the extending positions of the second lens frame 4 for wide, standard, and telephoto zooms, respectively.

Further, the first grooved cam 2a for driving the second lens frame 4 changes from position Pwc to P2 at the rotational position of the cam ring 2 corresponding to the range of the wide region Rw. The cam position is No. 1.

Provides a feeding position for focus adjustment from close subject distance to ■ during wide zooming of the lens frame 3. Further, the first groove cam 2a corresponding to the S' range of the standard area R telephoto area R1 also changes from the position Psc''rc to P and P, respectively, and similarly, the So
OToO These cam positions provide the focusing position of the second lens frame 4 during standard or telephoto zooming, from close range to wide range. In addition, the first and second groove cams 2
Areas CA and CB of a and 2b are extension position switching sections between wide-standard and standard-tele, respectively, and photographing is not performed in these sections. In addition, the first and second groove cams 2
A zoom/focus position encoder 14 formed of a resistive film or the like for detecting the operating position of the cam ring 2 is connected to the cam ring 2.
The operating position is detected by a conductive brush (not shown) fixed to the fixed frame 1 and output to a zoom or focus control device (not shown).

The zooming and focusing operations of the zoom lens barrel of this embodiment configured as described above will be explained.

First, the cam ring 2 is rotated by the drive motor 7 based on a zooming instruction. That is, the area R corresponding to the designated zoom of the second grooved cam 2b.

The cam ring 2 is rotated so that the second drive pin 6 is located at either Ts or Rr. Next, the position of the first groove cam 2a corresponding to the subject distance is determined according to instructions from the focus control device, that is, the wide angle of each zoom.

Focusing range P ~ p corresponding to standard and tele range
, p −p , p −p WC
woo sc Soo TCTo.

The cam ring 2 is rotated by the drive motor 7 so that the second drive bin 5 is positioned at one of the designated focus positions. In this case, the second drive bin 6 is not driven.

In this way, the first and second lens frames 3 and 4 are extended to the specified zoom position, and the second lens frame 3 is further moved to the focusing position, thereby completing the zooming and focusing operations. Note that in the above drive system, focusing drive is performed following zooming drive, but if the zoom point and subject distance are given,
Since the rotational position of the cam ring 2 is determined in advance, it is also possible to directly drive the cam ring to the zoom and focus position.

As mentioned above, the zoom lens barrel of this embodiment has a wide-angle lens for zooming and focusing.
A drive motor that constitutes one drive system that performs standard and telephoto zoom specification operations and focusing operations for each zoom state, as well as first and second motors that are driven by the drive system.
This enables the use of a cam ring, which is an integral member having grooved cams. Therefore, according to this embodiment, a frame member with a multilayer structure is required to drive the focusing lens group as shown in the conventional zoom lens barrel described above, or a zoom system and a focus system are required. This eliminates the drawbacks such as the need for two drive systems. Also,
The encoder and the like for detecting the cam position are also single, which further simplifies the design.

In the above embodiment, the zoom designation is in three stages: wide, standard, and telephoto, but it is also possible to use a grooved cam structure with an increased number of stages to precisely designate the zoom point. Furthermore, although the cam ring of the above embodiment has a 1.2-groove cam provided on an integrally molded member, the 1.2-groove cam does not necessarily need to be provided on an integrally molded member. Depending on the shape of the lens barrel, 1.2
The gist of the present invention is also applicable even if the cam grooves are provided in separate cam members and both are driven synchronously via a connecting member such as a gear, lever, or pin. Furthermore,
In this example, the zoom lens has a two-group lens configuration, but it can also be applied to a zoom lens with other configurations, for example, a four-group configuration. By providing the above-mentioned rest area on the cam, and further providing the cam for driving the lens group involved in focusing with a cam shape for driving the flash from a close distance at a plurality of positions corresponding to the above-mentioned rest area. It is also possible to realize a zoom lens barrel to which the gist of the present invention is applied. Furthermore, by arranging a plurality of cams in the circumferential direction, stability can be further improved.

[Effects of the Invention] As described above, the zoom lens drive mechanism of the present invention has the following effects:
A plurality of cams for driving a plurality of lens groups constituting a zoom lens are provided in an integrated member, and at least one of the drive cams is provided with a driver stop portion, and the corresponding lens group is moved while the cam is at rest. Since the focus adjustment is made, according to the present invention, the cam ring for driving the lens can be an integral member, and the drive mechanism for the lens group for focus adjustment can be simplified, and furthermore, the drive system such as the drive motor can be integrated into one. It can be done. Therefore, as a zoom lens barrel, it is possible to create a zoom lens drive mechanism that has remarkable effects such as a more compact design, an advantage in the arrangement of the drive system motor, and a reduction in the number of parts, which is advantageous in terms of cost. can be provided.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a main part of a zoom lens barrel to which a zoom lens drive mechanism according to an embodiment of the present invention is applied, and FIG. 2 is a perspective view of a main part of the zoom lens barrel shown in FIG. 1 above. , Fig. 3 is a developed view of the main parts of the cam ring and fixed frame of the zoom lens barrel shown in Fig. 1 above, Fig. 4 is a vertical sectional view of main parts of the zoom lens barrel showing a conventional example, 4 is an exploded view of the main parts of the cam ring and fixed frame of the zoom lens barrel shown in FIG. 4. FIG. 2...Cam ring (integral member) 2a...
...First groove cam (a cam with a shape that allows focus adjustment) 2b...Second groove cam (a cam with a shape that makes it pause) 10...First group lens (a cam with a predetermined shape) (lens group that can be moved according to the lens group)

Claims (1)

[Claims] (1) In a zoom lens drive mechanism that drives a zoom lens having a predetermined lens group and a movable lens corresponding to the lens group, the predetermined lens group is moved at multiple positions with respect to the optical axis direction. A cam having a shape for stopping the lens group and a cam having a shape capable of adjusting the focus by moving the corresponding lens group while the predetermined lens group is at rest are provided in an integrated member. Zoom lens drive mechanism.