JPH1138304A - Variable focal distance lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a variable focal distance lens capable of enhancing the accuracy between lens groups with a simple constitution in which the number of components is reduced and which can be inexpensively constituted. SOLUTION: The distance between a first lens group 11 on a main driving side and a second lens group 12 on a driven side is changed by a rotary cam 38, and a rear frame 14 on the side of the second lens group 12 is brought into contact with the cam side of the rotary cam 38 by a spring. The rotary cam 38 is driven by the rotational angle and in a rotating direction corresponding to the moving quantity and the moving direction of the first lens group 11 by a driving mechanism 43. A focal distance that is the distance between the first lens group 11 on the main driving side and the second lens group 12 on the driven side is regulated by the distance from the center of rotation to the cam side of the rotary cam 38.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable focal length lens having a variable focal length.

[0002]

2. Description of the Related Art In general, a variable focal length lens called a zoom lens is widely used in the field of photographic equipment. This variable focal length lens has a variable focal length from a wide angle to a telephoto range, and usually has a first lens group and a second lens group each movable along an optical axis. An arbitrary focal length is obtained by changing the distance between the first lens group and the second lens group.

[0003] As a device for changing the distance between lens groups of such a variable focal length lens, for example, a configuration described in US Pat. No. 5,333,024 is known. This US Pat. No. 5,333,024 discloses a flat cam arranged along the optical axis direction, the distance between the front lens group and the rear lens group movable along the optical axis direction,
This is changed by a cam follower mechanism in which a pair of L-shaped members are combined in a scissor shape. That is, with the movement of the front lens group, one end of the cam follower mechanism is moved along the cam surfaces formed on both sides of the flat cam, and the other end of the cam follower mechanism changes the distance between the rear group lens and the desired focus. I try to get distance.

[0004]

However, in the configuration described in US Pat. No. 5,333,024, a pair of L
The number of parts is large, such as the use of a cam follower mechanism combining scissor-shaped members, and the structure is complicated.
It is difficult to obtain the accuracy of the lens interval due to the accuracy of each part and the stacking of each other, and there is a problem that the cost is high due to the large number of parts.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a variable focal length lens having a simple structure with a small number of parts, high accuracy between lens groups, and low cost. The purpose is to:

[0006]

According to a first aspect of the present invention, there is provided a variable focal length lens, wherein the first lens group is a driving side movable along an optical axis, and the first lens group is movable along the optical axis. A second lens group that is a driven side of the first lens group; and a cam side. The second lens group side contacts the cam side, and the focal length is defined in accordance with the distance between the rotation center and the cam side. A rotary cam for varying the focal length provided on the first lens group side, and a drive mechanism for driving the rotary cam at a rotation angle and a rotation direction corresponding to the moving amount and the moving direction of the first lens group. The distance between the first lens group on the driving side and the second lens group on the driven side is changed by a rotating cam, and the cam side of this rotating cam is brought into contact with the second lens group side. Let Is driven by a drive mechanism at a rotation angle and a rotation direction corresponding to the movement amount and the movement direction of the first lens group, and the first drive which becomes the main driving side by the distance from the rotation center of the rotation cam to the cam side. The focal length is defined as the distance between the lens group and the second lens group on the driven side.

According to a second aspect of the present invention, the variable focal length lens is a first lens group which is movable along the optical axis and is driven by the first lens group which is movable along the optical axis. A plurality of lens groups on the side, each having a cam side, the plurality of lens groups being in contact with these cam sides, and defining a focal length corresponding to a distance between each rotation center and the cam side. A plurality of focal length variable rotary cams respectively provided on one lens group side, and a drive mechanism for driving these rotary cams in a rotation angle and a rotation direction corresponding to a moving amount and a moving direction of the first lens group. The distance between the first lens group on the driving side and the plurality of lens groups on the driven side is changed by the respective rotation cams. The plurality of lens groups are brought into contact with the respective cam sides of the cam, and these rotating cams are driven by a driving mechanism at a rotation angle and a rotation direction corresponding to the moving amount and the moving direction of the first lens group. The focal length, which is the distance between the first lens group on the driving side and the plurality of lens groups on the driven side, is defined by the distance from the rotation center to the cam side.

According to a third aspect of the present invention, there is provided the variable focal length lens according to the first or second aspect, wherein the cam side of the rotary cam for varying the focal length has a specific focus when the focal length is varied by rotation. The focus is fixed at a specific distance when the focal length is changed.

According to a fourth aspect of the present invention, there is provided a variable focal length lens according to the first or second aspect, wherein the cam side of the rotary cam for varying the focal length is focused by the focal length when the focal length is varied by rotation. The position is changed to a specific subject position. When the focal length is changed, the focal position is changed to a specific subject position according to the focal length.

According to a fifth aspect of the present invention, in the variable focal length lens according to the first or second aspect, the cam side of the rotary cam for varying the focal length has at least two focal points when the focal length is varied by rotation. The distance from the rotation center that enables focusing at a distance is formed in a step shape including the same part, and when the focal length is changed,
A step zoom that allows focusing at at least two focal lengths is possible.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the variable focal length lens according to the present invention will be described below with reference to the drawings.

In FIGS. 1 and 3, reference numeral 11 denotes a first lens group, and the optical axis X of the first lens group 11 is shown.
A second lens group 12 is disposed on the rear side along the line, and the first lens group 11 is held by the front frame 13 and the second lens group 12 is held by the rear frame 14. Further, the front frame 13 is integrally attached to a front portion inside the lens barrel 15, and the lens barrel 15 is disposed along a direction of the optical axis X in a lens frame 17 integrally attached to the main body 16. It is attached to be able to enter and exit. The shutter mechanism and the aperture mechanism are not shown.

Here, the front frame 13 is integrally formed to the lower part as shown in FIG. 4, and a guide hole 13a provided in the lower central part is provided with a guide shaft 19 as shown in FIGS.
3 and 6 are slidably fitted along the axial direction, and have a nut 21 as shown in FIGS.
The nut 21 is screwed with the drive screw 20. The guide shaft 19 and the drive screw 20 are arranged in parallel with the optical axis X, and have both ends at the holes 17a and 17b of the lens frame 17 and the holes 16a and 16a at the body 16 respectively.
Held by 16b. Of course, both ends of the drive screw 20 are rotatably supported by the holes 17b and 16b.

Therefore, by rotating the drive screw 20 by the drive mechanism 23, the front frame 13 integrated with the nut 21 screwed to the drive screw 20 and the first lens group 11 held by the front frame 13 The lens barrel 15 to which the front frame 13 is integrally attached moves forward and backward along the optical axis X, so that the lens barrel 15 can enter and exit the lens barrel 17.

As shown in FIG. 4, the drive mechanism 23 includes a drive motor 24, a drive gear 25 integrally attached to the drive screw 20 by caulking or the like, and a rotation shaft of the drive gear 25 and the motor 24. Gear train 26 configured between the motor gear 24a and the motor gear 24a integrally attached to the motor gear 24a.
It is constituted by. Here, the motor 24 is mounted on the lens frame 17 side as shown in FIG.
The gears 26a and 26b are rotatably supported by either the lens frame 17 or the main body 16, respectively.

The motor gear 24a is also meshed with the pulse gear 27, and the wing 27a of the pulse gear 27 is disposed so as to pass through the detecting section 28a of the photo interrupter 28. Therefore, with the rotation of the motor 24, the pulse gear
27 also rotates, and the wing 27a is the detector of the photointerrupter 28.
By passing through 28a, the number of rotations of the motor 24 can be detected by the photo interrupter 28.

As shown in FIG. 1, the rear frame 14 has guide holes 14a and 14b provided vertically, and a guide pin 31 one end of which is integrally press-fitted on the rear surface side of the front frame 13, and an axial direction. Are slidably fitted along. The guide pins 31 are provided in parallel with the optical axis X, and the rear frame 14 is also movably guided along the optical axis X.

As shown in FIGS. 3 and 4, a front frame 13 and a rear frame 14 are provided beside the guide pins 31 provided at the lower portion.
Is provided between the rear frame 14 and
Is always acted on by the spring 32 on the front frame 13 side.

In FIGS. 1 and 2, reference numeral 34 denotes a cam substrate. The cam substrate 34 has two long holes 34a and 34b formed along the optical axis X as shown in FIG. It is attached to the front frame 13 via two front frame bosses 13b, 13c, and is configured to be displaceable in the optical axis X direction by the length of the long holes 34a, 34b. The cam substrate 34 is urged forward by a spring 35 provided between the cam frame 34 and the front frame 13, and the position in the optical axis X direction is similarly adjusted by a screw 36 provided between the cam substrate 34 and the front frame 13. . That is, the position of the cam substrate 34 in the optical axis X direction with respect to the front frame 13 changes according to the screwing amount of the screw 36, and this becomes the initial distance between the first lens group 11 and the second lens group 12.

A cam shaft 39 caulked on the cam substrate 34
A rotary cam 38 for changing the focal length is rotatably mounted around the. Therefore, the rotating cam 38 is connected to the first lens group 11 via the cam board 34, the front frame 13, and the like.
Attached to the side. A gear section 40 is integrally attached to the lower side of the rotating cam 38, and the gear section 40
Is in mesh with the cam gear 41. The cam gear 41 is rotatably mounted around a gear shaft 42 caulked to the cam substrate 34, and is provided laterally in parallel with the optical axis X,
The rotation cam 38 also meshes with a rack 43 as a drive mechanism for driving the rotation cam 38 in a rotation angle and a rotation direction corresponding to the moving amount and the moving direction of the first lens group 11.

The rack 43 is integrally screwed to the main body 16. Even if the front frame 13 moves along the optical axis X, the rack 43 does not move. The rotary cam 38 attached to the front frame 13 via the cam board 34 is rotationally driven via a cam gear 41 and a gear unit 40. The rotation angle of the rotary cam 38 driven by the rack 43 is proportional to the amount of movement of the first lens group 11 held on the front frame 13, and the rotation direction corresponds to the same movement direction.

A cam side 38a on the outer periphery of the rotary cam 38 has
The lower part 14 of the rear frame 14 which is a member on the second lens group 12 side
c is in pressure contact. That is, the rear frame 14 is urged toward the front frame 13 by the spring 32 shown in FIG. 3, and the lower portion 14c of the rear frame 14 is pressed against and contacts the cam side 38a of the rotary cam 38 by the spring force. Therefore, the spring 32 functions as a pressing member for bringing the lower portion 14c of the second lens group 12 into contact with the cam side 38a of the rotating cam 38.

Here, from the center of rotation of the rotating cam 38 to the cam side
The distance to 38a depends on the position of the cam side 38a,
With the rotation of the rotary cam 38 accompanying the movement of the front frame 13 in the optical axis X direction, the distance between the front frame 13 and the rear frame 14 in contact with the cam side 38a in the optical axis X direction, that is, the first lens group
The focal length, which is the distance between 11 and the second lens group 12, changes. Therefore, the rotating cam 38 defines the focal length of the variable focal length lens by the distance from the rotation center to the cam side 38a.

In FIGS. 2 and 4, a section 45 for a position switch is screwed to the lower side of the front frame 13 as shown in FIG. 5, and a print for zoom provided on the lens frame 17 is provided. Conductive pattern 4 on zoom substrate 46, which is the substrate
7, 48, 49
Together with 7, 48 and 49, it constitutes a position switch. That is, the section 45 moves while short-circuiting between the conductive patterns 47 and 48 or between the conductive patterns 47 and 49 with the movement of the front frame 13 in the optical axis X direction.
The drive motor 24 is controlled via an electric circuit (not shown) in accordance with a position signal derived from terminals 47a, 48a, 49a provided for the respective 8, 49.

The zoom substrate 46 has two long holes 46a and 46b formed along the optical axis X as shown in FIG.
And is attached to the lens frame 14 via two bosses 14d and 14e provided on the lens frame 14, and is configured to be displaceable in the optical axis X direction by the length of the long holes 46a and 46b. Have been. Therefore, when adjusting the distance between the first and second lens groups 11 and 12 at the time of initial setting or the like, the zoom substrate 46 is fixed at a predetermined position by screws (not shown) or the like.

Next, the operation of the above embodiment will be described.

First, when the drive motor 24 is rotated by the control of an electric circuit (not shown) and the drive screw 20 is rotated through the reduction gear train 26 and the drive gear 25, the nut 21 screwed to the drive screw 20 is rotated. Through front frame 13
Moves forward along the optical axis X, for example. By this operation, the cam board 34 attached to the front frame 13 also advances,
The cam gear 41 on the cam board 34 also moves forward. On the other hand, since the rack 43 attached to the main body 16 is in a fixed state, the cam gear 41 meshing with the rack 43 is fixed.
Is rotated to rotate the rotary cam 38 via the gear unit 40 at a rotation angle proportional to the amount of movement of the front frame 13.

By the rotation of the rotary cam 38, the lower portion 14c of the rear frame 14 which is in press contact with the cam side 38a of the rotary cam 38 changes the distance from the rotation center of the cam side 38a in the contact state. Move along the optical axis X in accordance with. For this reason, the distance between the first lens group 11 of the front frame 13 and the second lens group 12 of the rear frame 14 changes, and the focal length changes.

Further, as the front frame 13 advances, the position switch piece 45 also moves in the same direction, and the conductive patterns 47 and 48 or the conductive patterns 49 formed on the zoom substrate 46 are formed.
As it moves upward, the terminals 47a, 48a, and 49a are turned on or off, and a signal is sent to an electric circuit (not shown) to control the drive motor 24.

These operations are the same when the front frame 13 is driven backward.

Here, the lower portion 14c of the rear frame 14 is
When the distance from the center of rotation is in contact with the same portion, the front frame and the rear frame 14 move forward with the distance between the front frame 13 and the rear frame 14 unchanged. That is, focusing is performed without changing the focal length. Therefore, by providing a plurality of portions where the distance from the rotation center does not change within a certain range at different distances from each other as the shape of the cam side 38a, a so-called step zoom in which focusing is performed at a plurality of focal lengths can be achieved. it can.

Although the shape of the cam side 38a has been described in the case of the step zoom in which there is a portion having the same distance from the center of rotation, the shape is not limited to such a shape. When changing the focal length to move along X, the cam side is fixed so that the focal point is fixed at a specific distance.
38a may be formed smoothly. Similarly, when the focal length is changed, the cam side 38a may be formed smoothly so that the focal position is changed to a specific subject position by the focal length.

Also, by changing the rotary cam 38 without changing the lens group, variable focal length lenses of various specifications can be produced.

In the above embodiment, the case where the first lens group 11 on the driven side and the second lens group 12 on the driven side are combined has been described. However, the first lens group on the driven side is described. By providing a plurality of lens groups on the driven side with respect to 11 and providing rotating cams corresponding to the plurality of lens groups, and connecting these rotating cams with a gear train, three or more zoom lenses are similarly configured. be able to.

[0035]

According to the variable focal length lens according to the first aspect, the distance between the first lens group on the driving side and the second lens group on the driving side is changed by the rotating cam, and this rotating cam is changed. The second lens group side is brought into contact with the cam side of the first lens group, and this rotary cam is driven by a drive mechanism at a rotation angle and a rotation direction corresponding to the moving amount and the moving direction of the first lens group, and the rotation center of the rotary cam The focal length, which is the distance between the first lens group on the driving side and the second lens group on the driven side, is defined by the distance from to the cam side, so that the first lens group, the second lens group, Since the distance accuracy between the two is determined by the accuracy of the rotating cam alone, a high variable focal length accuracy can be easily obtained by increasing the distance accuracy of the rotating cam, and the number of parts is small. It is also possible to reduce the cost for.

According to the variable focal length lens of the second aspect, the distance between the first lens group on the driving side and the plurality of lens groups on the driven side is changed by each of the rotating cams, and the distance between the first and second lens groups is changed. A plurality of lens groups are brought into contact with the respective cam sides, and these rotary cams are driven by a drive mechanism at a rotation angle and a rotation direction corresponding to the moving amount and the moving direction of the first lens group. The distance from the first lens group to the cam side defines the focal length, which is the distance between the first lens group on the driving side and the plurality of lens groups on the driven side. Since the distance accuracy between them is determined only by the accuracy of the rotating cam, the variable focal length accuracy can be easily increased by increasing the distance accuracy of the rotating cam. Can be obtained, it is also possible to reduce the cost for a small number of components.

According to the variable focal length lens according to the third aspect, in addition to the variable focal length lens according to the first or second aspect, the cam side of the rotary cam for changing the focal length can be used when the focal length is changed by rotation. Is fixed at a specific distance, and the focal point can be fixed at a specific distance when the focal length is changed.

According to the variable focal length lens according to the fourth aspect, in addition to the variable focal length lens according to the first or second aspect, the cam side of the rotary cam for varying the focal length is used when the focal length is varied by rotation. The focal position is changed to a specific subject position depending on the distance. When the focal length is changed, the focal position can be changed according to the focal length.

According to the variable focal length lens according to the fifth aspect, in addition to the variable focal length lens according to the first or second aspect, the cam side of the rotary cam for varying the focal length is at least provided when the focal length is varied by rotation. A step zoom that enables focusing at two focal lengths is formed in a step shape including the same portion as the distance from the rotation center that enables focusing at two focal lengths. Can be made possible.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a main configuration of an embodiment of a variable focal length lens according to the present invention.

FIG. 2 is a bottom view of the same.

FIG. 3 is another cross-sectional view of the configuration of the main part of the above.

FIG. 4 is a front view showing a configuration of a main part of the above.

FIG. 5 is a sectional view taken along line VV of FIG. 4;

FIG. 6 is a sectional view taken along the line VI-VI of FIG. 4;

[Explanation of symbols]

 11 First lens group 12 Second lens group 38 Rotating cam 38a Cam side 43 Rack as drive mechanism X Optical axis

Claims (5)

[Claims] A first lens group movable along the optical axis and serving as a driving side; and a second lens group movable along the optical axis and serving as a driven side of the first lens group. The second lens group side contacts the cam side to define a focal length corresponding to the distance between the center of rotation and the cam side, and to provide a focal length variable provided on the first lens group side. A variable focal length lens, comprising: a rotary cam, and a drive mechanism that drives the rotary cam in a rotation angle and a rotation direction corresponding to a moving amount and a moving direction of the first lens group. 2. A first lens group which is movable along an optical axis and is on a driving side, and a plurality of lens groups which is movable along the optical axis and is on a driven side of the first lens group. Each of the plurality of lens groups has a cam side and each of the plurality of lens groups comes into contact with the cam side to define a focal length corresponding to a distance between each rotation center and the cam side.
A plurality of rotary cams for varying the focal length respectively provided on the lens group side of the lens group; and a drive mechanism for driving these rotary cams at a rotation angle and a rotation direction corresponding to the moving amount and the moving direction of the first lens group. A variable focal length lens comprising: 3. The cam side of the rotary cam for changing the focal length is:
3. The variable focal length lens according to claim 1, wherein the focal length is fixed at a specific distance when the focal length is varied by rotation. 4. A cam side of a rotary cam for changing a focal length,
3. The variable focal length lens according to claim 1, wherein, when the focal length is varied by rotation, the focal position is changed to a specific subject position by the focal length. 5. A cam side of a rotary cam for changing a focal length,
3. The variable focus according to claim 1, wherein when the focal length is changed by rotation, the distance from the center of rotation enabling focusing at at least two focal lengths is formed in a stepped shape including the same portion. Distance lens.