JP2019133113A - Lens device - Google Patents

Abstract

To provide a lens device in which a position of an optical element to be loaded on both a subject side and an image plane side by biasing means can be precisely determined.SOLUTION: The lens device includes a first optical element support frame 7 holding a first optical element and relatively movable in an optical axis direction, and first biasing means 9 and second biasing means 10 biasing the first optical element support frame 7 on an image plane side and a subject side of the element, respectively. The direction of resultant force of a load biased by the first biasing means 9 and a load biased by the second biasing means 10 is constant in the range where the first optical element support frame 7 relatively moves in the optical axis direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lens apparatus having a drive mechanism for an optical element such as a lens.

  2. Description of the Related Art Conventionally, a lens device that performs zoom, focus, and light amount adjustment by relatively moving an optical element such as a lens frame that holds glass or a diaphragm device that adjusts the light amount in the optical axis direction is known. In such a lens apparatus, in order to accurately determine the position of each optical element, a structure in which the optical element is urged in one direction by a spring member is generally used.

  In Patent Document 1, a spring is provided between the diaphragm device and the lens group support frame provided before and after the diaphragm device, and one side provided between the lens group support frame and the diaphragm device when the lens interval changes. A structure is disclosed in which the other spring is compressed after the first spring is completely compressed. Patent Document 2 discloses a structure in which a plurality of spring members are provided between two types of zoom lens groups, and the urging force applied to the cam followers provided in each zoom lens group is made uniform.

JP 2013-152325 A Japanese Patent Laid-Open No. 11-326734

  However, in the technique disclosed in Patent Document 1 described above, when the lens group support frame moves along different trajectories, the position of the diaphragm device may not be stabilized depending on the load of two types of springs. In the technique disclosed in Patent Document 2, when one zoom lens group is urged by a spring member from both the subject side and the image plane side, the load direction is reversed depending on the zoom position, The position of the zoom lens group may not be stable.

  In view of the above problems, a lens apparatus according to an aspect of the present invention includes a first optical element support frame that holds a first optical element and is relatively movable in the optical axis direction, and the first optical element support. A first urging means and a second urging means for urging the frame from the image surface side and the subject side, respectively, wherein the urging load of the first urging means; The direction of the resultant force of the urging load of the second urging means is constant over a range in which the first optical element support frame relatively moves in the optical axis direction.

  According to one aspect of the present invention, a load is applied to the optical element support frame from both the image plane side and the subject side by the biasing means, and the optical element support frame can be biased in a certain direction within the driving range of the optical element. Therefore, the position of the optical element can be determined relatively accurately over the driving range.

It is sectional drawing of the zoom part mechanism of the lens apparatus of one Example by this invention. It is a disassembled perspective view of the lens apparatus of one Example by this invention. It is an expanded view of the cam ring in one Example by this invention. It is a figure which shows the relationship of the force of the load by the spring member in one Example by this invention.

  In the configuration according to one aspect of the present invention, the optical element support frame that holds the optical element is urged from the image plane side and the subject side by using the first urging unit and the second urging unit, respectively. And the direction of the resultant force of the urging load of the first and second urging means is set so as to be constant over the range in which the optical element support frame moves relatively in the optical axis direction. Such a lens device can be used for an imaging device, for example, by changing the focal length or the imaging position by relative driving in the optical axis direction of a plurality of optical elements. Since the state in which the direction of the resultant force of the urging load is reversed does not occur in the driving range of the optical element, the position of the optical element can be determined precisely, and the optical performance of the lens device is improved.

  In the following, preferred embodiments of the present invention will be described in detail based on the examples shown in FIGS.

Example 1
With reference to FIGS. 1-4, the lens apparatus by Example 1 of this invention is demonstrated. FIG. 1 is a cross-sectional view of the zoom mechanism section 1 of the lens device according to the present embodiment including the optical axis O, FIG. 2 is an exploded perspective view, and FIG. 3 is an exploded view of the cam ring 3.

  The zoom mechanism unit 1 that drives the zoom lens group of the lens apparatus according to the present exemplary embodiment includes a mechanism that relatively moves a plurality of (3 in the illustrated example) optical element support frames. The zoom mechanism unit 1 is capable of rotating a lens barrel 2 having a linear groove 2a for translating a plurality of lens group support frames along the optical axis O, a cam ring 3 having a cam groove, and a cam ring 3. And a cam mechanism that uses a cam follower 5. The cam ring 3 is formed with cam grooves 3a and 3b which are trajectories of the lens group support frames 6 and 7. Here, the cam groove of the locus of the lens group support frame 6 is 3a, and the cam groove of the locus of the lens group support frame 7 is 3b.

  The relatively movable lens group support frames 6 and 7 each have a cam follower 5 on the outer periphery, and the cam follower 5 is engaged with the cam groove of the cam ring 3 and the linear groove 2a of the lens barrel 2. The lens group support frames 6 and 7 are held by the zoom mechanism unit 1. The diaphragm unit 8 which is another type of optical element support frame is fixed to the lens barrel 2. Spring members 9 and 10 which are urging means are compression springs. The spring member 9 is sandwiched between the aperture unit 8 and the lens group support frame 7, and the spring member 10 is sandwiched between the lens group support frame 6 and the lens group support frame 7. Is done. Further, the spring members 9 and 10 are always held in a compressed state throughout the entire zoom range. The cam ring 3 is pin-coupled to a zoom ring (not shown) provided on the outer periphery of the lens barrel 2. Since the distance between the lens group support frames 6 and 7 varies depending on the locus of the cam groove, the load applied by the spring members 9 and 10 varies depending on the zoom position.

  The condition of the load by the spring member in the lens apparatus of the present embodiment will be described. The load of the spring member 9 is P1, and the load of the spring member 10 is P2. That is, the load applied to the lens group support frame 6 is P2, and the load applied to the lens group support frame 7 is a resultant force of P1 and P2. In this embodiment, the load directions of P1 and P2 applied to the lens group support frame 7 are opposite to each other. If the direction of P1 (subject direction) is positive, the direction of P2 (image plane direction) is Negative. The direction of the load P2 applied to the lens group support frame 6 is always the direction toward the subject.

  FIG. 4 shows the relationship of the force of the spring member depending on the position of the lens group support frame. The broken line at the rightmost end in FIG. 4 indicates the position of the aperture unit 8. First, the relationship between the spring loads P1 and P2 depending on the distance L1 between the lens group support frames 6 and 7 will be described. The load (P2min) at the position where the interval is maximum (L1max) is larger than the load (P1a) at the same zoom position, and the load (P2max) at the position where the interval is minimum (L1min) is the same zoom. It is set to be larger than the load (P1b) at the position. Next, the relationship between the spring loads P1 and P2 depending on the distance L2 between the lens group support frame 7 and the aperture unit 6 will be described. The load (P1min) at the position where the interval is maximum (L2max) is smaller than the load (P2a) at the same zoom position, and the load (P1max) at the position where the interval is minimum (L2min) is the same zoom position. Is set to be smaller than the load (P2b).

  With the above load conditions, the resultant force (P1 + P2) applied to the lens group support frame 7 is set so that the load is always applied in a constant direction (direction on the image plane side) throughout the entire zoom range. In this embodiment, with respect to the movement of the two types of lens groups, a load is applied to one lens group from both the subject side and the image plane side by the biasing means. Similarly, in the case of three or more types of lens groups, if a plurality of lens groups to which loads are applied from both the object side and the image plane side by the biasing means are provided, and the load direction is set as described above, Similar effects can be obtained. However, with the above setting, in most cases, the lens group support frame 7 satisfies P1 + P2> 0 or P1 + P2 <0 in the entire driving range, but it cannot be said that this is necessarily the entire driving range. Therefore, it is confirmed that the resultant force of the load is always in a constant direction throughout the entire drive, and if it is found that this is not the case, adjustment or resetting may be performed and this may be repeated.

  The movement of the lens group support frames 6 and 7 in the lens apparatus of the present embodiment having the above structure will be described. By rotating the zoom ring (not shown), the cam ring 3 is rotated, and the lens group support frames 6 and 7 are moved relative to each other in the optical axis direction according to the trajectory of the cam grooves 3a and 3b to change the magnification. At this time, the lens group support frames 6 and 7 are always urged by the spring members 9 and 10 in a constant direction over the entire zoom range. Therefore, the cam followers 5 provided on the lens group support frames 6 and 7 can always be brought into contact with the side surfaces of the cam grooves 3a and 3b, and the positions of the lens group support frames 6 and 7 can be accurately maintained. It becomes. In an optical system corresponding to a camera equipped with a large-format sensor having a large image sensor, the configuration of this embodiment is particularly effective because high performance optical performance is required.

  In the present embodiment, the configuration of the spring member that acts on the lens group support frame of the zoom unit has been described, but the same operation can be achieved even in a configuration in which optical elements such as the focus unit and the iris unit move in the optical axis direction. Is possible. In this embodiment, the cam structure using the cam follower 5 has been described. However, the present invention is not limited to the cam structure, and a similar operation is possible as long as the mechanism drives the optical element in the optical axis direction. Furthermore, although the spring members 9 and 10 are compression springs, this is not restrictive. With respect to an optical element to which a load is applied by a plurality of springs (biasing means), the same operation is possible if the resultant force of the load by the spring member, which is the urging means, is constant in the entire driving area.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to the said Example, A various deformation | transformation and change are possible within the range of the summary.

3a, 3b: Cam groove 5: Cam follower 6: Lens group support frame (second optical element support frame)
7: Lens group support frame (first optical element support frame)
8: Aperture unit (third optical element support frame)
9: Spring member (first biasing means)
10: Spring member (second biasing means)

Claims (7)

A first optical element support frame that holds the first optical element and is relatively movable in the optical axis direction, and a first optical element support frame that biases the first optical element support frame from the image plane side and the subject side, respectively. A first biasing means and a second biasing means,
The direction of the resultant force of the urging load of the first urging means and the urging load of the second urging means is such that the first optical element support frame moves relatively in the optical axis direction. A lens apparatus characterized by being constant over a range. A plurality of lens group support frames including at least two types of lens groups including the first optical element; and a plurality of lens group support frames each including the first optical element support frame capable of moving in the optical axis direction while holding the lens groups. Two types of spring members including the first biasing means and the second biasing means for biasing the lens group support frame from the image plane side and the subject side;
When the spring load of the first spring member including the first urging means is P1, and the spring load of the second spring member including the second urging means is P2, each lens group is light. 2. The lens device according to claim 1, wherein P1 + P2> 0 or P1 + P2 <0 is satisfied over an entire region relatively moving in the axial direction, and each lens group support frame is urged in the predetermined direction. A second optical element support frame that holds the second optical element and is relatively movable in the optical axis direction; and a third optical element support frame that is relatively movable in the optical axis direction by holding the third optical element. An optical element support frame,
The first spring member, which is the first biasing means, is provided between the first optical element support frame and the third optical element support frame, and is a second biasing means. 2. The lens device according to claim 1, wherein the second spring member is provided between the second optical element support frame and the first optical element support frame.   4. The lens according to claim 3, wherein each of the first optical element support frame and the second optical element support frame is a lens group support frame, and the third optical element support frame is an aperture unit. apparatus.   5. The lens device according to claim 1, wherein each of the first biasing unit and the second biasing unit is a compression spring.   6. The lens device according to claim 1, wherein the first optical element support frame is relatively movable in a direction of an optical axis by a cam mechanism.   The lens apparatus according to claim 1, wherein the first optical element is a zoom lens group.