JP6166543B2 - Lens apparatus and imaging apparatus having the same - Google Patents

Description

  The present invention relates to a lens apparatus that performs focusing or zooming by moving an optical element in the optical axis direction, and in particular, the rotational movement of an operation member provided on the outer periphery of the lens apparatus in the optical axis direction of the optical element. The present invention relates to a lens apparatus having a mechanism for converting movement and an imaging apparatus having the lens apparatus.

  Conventionally, as a means for moving a lens holding barrel holding an optical element in an optical axis direction, a lens device using a cam that rotates in conjunction with rotation of an operation member provided on an outer peripheral portion of the lens device is known. Yes.

  For example, in Patent Document 1, three cam followers fixed to the outer peripheral portion of the lens holding barrel engage with three straight guide grooves provided on the fixed cylinder and three cam grooves provided on the cam ring, A lens device is disclosed that rotates outside the fixed barrel and moves the lens holding barrel in the optical axis direction.

  On the other hand, in a lens device that requires a rotation angle of an operating member that is operated when performing focusing or zooming, such as a movie shooting lens, to provide a cam ring with three cam grooves. In some cases, the lens holding barrel is moved by two or one cam groove. In such a lens apparatus, as a structure that stably supports the posture of the lens holding barrel, a structure in which a plurality of cam followers are used to support the lens supporting barrel with respect to the three rectilinear guide grooves as in Patent Document 2. Is generally used.

JP-A-7-294793 JP-A-8-262302

  However, in the lens device according to the related art as described above, no load is applied to the linear guide groove when an impact is applied in the optical axis direction, so that the full load is received by the cam groove and the cam follower. For this reason, in a lens device with a large moving group mass, such as when the lens held by the lens holding lens barrel has a large diameter, the dent in the cam groove that defines the position of the lens in the optical axis direction or damage to the cam follower There was a problem that was likely to occur.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a lens device having excellent impact resistance against impact in the optical axis direction while having an operation rotation angle of about half a circle or more for focusing or zooming.

To achieve the above object, a lens device of the present invention includes a fixed cylinder having a helical groove of multiple, is disposed inside the fixed cylinder, a plurality of first engaging each of said plurality of helical grooves a movable barrel having a cam follower, said are disposed on the outer peripheral side of the fixed cylinder, a rotatable ring portion, wherein are engaged ring portion slidably engaged, the light which is fixed to the moving cylinder with the axial direction positioning member, the position of the optical axis direction of the movable cylinder by the rotation position of the ring portion is determined, characterized in that.

  According to the present invention, it is possible to provide a lens device having excellent impact resistance against an impact in the optical axis direction while having an operation rotation angle of about a half turn or more for focusing or zooming.

Sectional drawing of the lens apparatus of Example 1 of this invention Sectional drawing of the principal part along the spiral groove of the lens apparatus of Example 1 of this invention Development relationship diagram of the groove of the fixed barrel and the cam ring definitive lens apparatus of Embodiment 1 Sectional drawing of the principal part along the spiral groove of the lens apparatus of Example 2 of this invention

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

  FIG. 1 is an overall sectional view of a lens apparatus 1 according to a first embodiment of the present invention. In the figure, the left side is the object side, and the right side is the image plane side. The lens apparatus 1 of the present invention includes an optical element 2 that is a variable magnification optical system, and can move the lens in the optical axis direction corresponding to the left-right direction in the drawing to continuously change the focal length of the lens. The optical element 2 is held by a movable cylinder 3, and the movable cylinder 3 is supported on the inner peripheral side of the fixed cylinder 4 so as to be slidable with respect to the fixed cylinder 4. By the rotation of the zoom operation ring 6, the movable cylinder 3 moves to a rotation angle regulated by the cam ring 5 and a position in the optical axis direction.

  FIG. 2 is a cross-sectional view of an essential part of the first embodiment of the lens apparatus 1 according to the present invention surrounded by a broken line in FIG.

  A plurality of cam follower mounting portions are provided on the outer peripheral portion of the movable cylinder 3, and in the present embodiment, the optical element 2 is directly held by the inner diameter portion. The fixed cylinder 4 is a member that does not move during zooming operation, and is connected to a connecting portion with an imaging device (not shown) to which the lens device 1 is attached. The fixed cylinder 4 is provided with three spiral grooves 4a at substantially equal intervals in the circumferential direction. The spiral groove 4a has a constant ratio of the length in the optical axis direction and the length in the circumferential direction in an arbitrary section on the groove, and is a groove represented by a straight line in the development view. Two guide cam followers 7 (first cam followers) are engaged with each spiral groove 4 a, and are fixed to the outer peripheral portion of the movable cylinder 3 positioned inside the fixed cylinder 4. 2 is a cross section of a three-dimensional curved surface along the spiral groove, the cam groove cam follower 8 (second cam follower), the two guide cam followers 7, and the spiral groove 4a. Is written on the same sheet over its entire length.

  With the above configuration, the movable cylinder 3 holding the optical element 2 is stably supported with respect to the fixed cylinder 4 with respect to the parallel eccentricity in the axial direction orthogonal to the optical axis and the tilt around the axis orthogonal to the optical axis. ing.

  The cam ring 5 and the zoom operation ring 6 (ring part) are fitted to the outer peripheral side of the fixed cylinder 4 and are rotatable around the optical axis. Since the cam ring 5 and the zoom operation ring 6 are connected by the connecting pin 10, the cam ring 5 and the zoom operation ring 6 rotate as a unit during the zoom operation.

One cam groove 5a is provided in the cam ring 5 in an angle range of 180 degrees, and a cam groove cam follower 8 which is an optical axis direction positioning member is engaged. This cam groove cam follower 8 is fixed to the outer peripheral portion of the movable cylinder 3 through one of the spiral grooves 4a. The ring part is slidably engaged with an optical axis direction positioning member fixed to the moving cylinder, and the position of the moving cylinder in the optical axis direction is determined by the rotation position of the ring part.

  An operation associated with the zoom operation of the thus configured lens apparatus of the present embodiment will be described below.

  When performing the zoom operation, the zoom operation ring 6 is rotated around the optical axis. Since the cam ring 5 rotates integrally with the zoom operation ring 6, the cam groove cam follower 8 moves to the position of the intersection where the center line of the inserted spiral groove 4a and the center line of the cam groove 5a intersect. As a result, the movable cylinder 3 holding the optical element 2 moves in the optical axis direction while rotating around the optical axis along the spiral groove 4a, and the focal length of the lens is changed. That is, the position of the movable cylinder 3 in the optical axis direction is uniquely determined by the rotation position of the zoom operation ring 6.

Next, the impact resistance of the lens apparatus of the present embodiment will be described below.
FIG. 3 is an explanatory view in which the developed views of the groove portions of the fixed cylinder 4 and the cam ring 5 are overlapped. In addition, the up-down direction in a figure represents the direction parallel to an optical axis.

  When the lens apparatus is dropped with the tip of the lens apparatus 1 facing downward, and the lens barrel first collides with something and stops moving downward in the figure, the moving group 9 is shown in FIG. In the figure, an inertial force in the downward direction (A direction) acts and an impact force is applied to the member that regulates the position in the optical axis direction. At this time, the members that restrict the position of the moving group 9 in the optical axis direction are the spiral groove 4a, the guide cam follower 7, the cam groove 5a, and the cam groove cam follower 8. Therefore, the impact force in the direction perpendicular to the contact surface and the reaction force on the contact surface of the spiral groove 4a and the guide cam follower 7 and the contact surface of the cam groove 5a and the cam groove cam follower 8 are indicated by arrows in FIG. Acts as follows. In the present embodiment, three spiral grooves 4a are provided on the circumference, and two guide cam followers 7 are engaged with each spiral groove 4a. Is receiving.

  Here, if the structure of the lens device is a combination of a straight guide groove and a cam groove as in the prior art, the straight guide groove and the guide cam follower do not regulate the position of the moving group in the optical axis direction. For this reason, the impact in the optical axis direction is received at only one contact surface between the cam groove and the cam groove cam follower.

  Compared with such a prior art, the lens structure of the present embodiment is superior in impact resistance because it can disperse the impact force in the case of an impact in the optical axis direction in seven places, and in the optical axis direction. It is possible to prevent damage to components that determine the position in the optical axis direction which is important for the moving optical element.

  Further, in the lens apparatus of the present embodiment, when the tip on the subject side is directed downward, the mass of the moving group 9 is also dispersed in the above-mentioned seven places, so that the load on the cam groove 5a is small. For this reason, the phenomenon in which the zoom operation ring 6 rotates by itself due to the weight of the moving group 9 can be suppressed as compared with the lens device of the prior art.

In the above embodiment, the guide cam follower 7 is engaged with the spiral groove 4a through which the cam groove cam follower 8 is inserted. However, the guide groove 7 and the guide cam follower 7 are engaged with each other. It is also possible to divide the spiral groove to be provided and provide both in different phases.
Two cam grooves 5 a can be provided on the circumference of the cam ring 5.
Further, when it is not necessary to make the operation rotation angle of the lens device wide, a configuration in which three cam grooves 5a are arranged in the cam ring 5 at equal intervals may be adopted.

  FIG. 4 is a side sectional view of an essential part in a second embodiment of a lens apparatus to which the present invention is applied. Hereinafter, differences from the first embodiment will be described.

  The optical element 22 is a focusing optical system of the lens device 21, and the focus of the lens can be changed by moving in the optical axis direction corresponding to the horizontal direction in the drawing.

  A plurality of cam follower mounting portions are provided on the outer peripheral portion of the movable barrel 23, and the focus barrel 20 that holds the optical element 22 is fixed to the inner diameter side.

  The fixed cylinder 24 is provided with three spiral grooves 24a at substantially equal intervals in the circumferential direction. A stepped cam follower 28 and a guide cam follower 27 (first cam follower) are engaged with each spiral groove 24 a and fixed to the outer peripheral portion of the movable cylinder 23. 4 is a cross-sectional view of a three-dimensional curved surface along the spiral groove, the guide cam follower 27, the stepped cam follower 28, and the spiral groove 24a extend over the entire length on the same sheet. Have been described.

  With the above-described configuration, the movable cylinder 23 holding the optical element 22 is stably supported with respect to the fixed cylinder 24, the parallel eccentricity in the axial direction orthogonal to the optical axis and the tilt around the axis orthogonal to the optical axis are restricted. ing.

  The stepped cam follower 28 includes two engaging portions having different engaging diameters, and the lower engaging portion having a small diameter is engaged with the spiral groove 24a. On the other hand, the upper engaging portion having a large diameter is engaged with three engaging holes 25a provided in the male helicoid 25 which is an optical axis direction positioning member. The male helicoid 25 has a male screw portion 25 b on the outer peripheral portion, and is screwed with a female screw portion 26 b of a female helicoid 26 (ring portion) that fits on the outer periphery of the fixed cylinder 24.

  An operation associated with the focus operation of the thus configured lens apparatus of the present embodiment will be described below.

  When performing the focusing operation, the female helicoid 26 at the outermost periphery of the lens device 21 is rotated around the optical axis. In the focus movement group 29 including the male helicoid 25, the movable direction is limited only in the direction along the spiral groove 24a by the stepped cam follower 28 and the guide cam follower 27. Therefore, the relative rotation of the male helicoid 25 and the female helicoid 26 is relatively small. Will occur. As a result, the moving group 29 moves in the optical axis direction along the lead of the screw portion, and the focus of the lens is changed. In this configuration, the rotation angle of the focus operation can be set to a half or more.

Next, the impact resistance of the lens apparatus of the present embodiment will be described below.
If the guide of the moving group is not a spiral groove but a rectilinear guide groove, the stepped cam follower receives the impact force in a concentrated manner when the object-side tip of the lens device is dropped downward. In contrast, in the structure of this embodiment, the contact surface between the spiral groove 24a and the guide cam follower 27 and the contact surface between the spiral groove 24a and the stepped cam follower 28 are configured to regulate the position in the optical axis direction. The impact force is dispersed at these contact surfaces, and it is possible to avoid the impact force from being concentrated on the stepped cam follower.

  As described above, the lens device according to the present embodiment is excellent in impact resistance because the impact force applied in the optical axis direction can be distributed to a large number of components, and damage to the components can be prevented.

  In this embodiment, the cam follower that slidably engages with the spiral groove 24a and the member that fits into the engagement hole 25a of the male helicoid 25 and fixes the male helicoid 25 to the moving cylinder 23 are integrally configured. doing. For this reason, the number of parts can be reduced and the configuration of the apparatus can be simplified. The same effect can be obtained by integrally configuring the guide cam follower 7 and the cam groove cam follower 8 of the first embodiment.

  In addition, by including the lens device of the present invention and an image sensor that receives a subject image by the lens device, the positioning and moving mechanism is not easily damaged even when subjected to an impact that is an effect of the lens device of the present invention. It is possible to realize an imaging apparatus capable of preventing a decrease in element positioning accuracy (optical performance).

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

2, 22 ... Optical elements 3, 23 ... Moving cylinders 4, 24 ... Fixed cylinders 4a, 24a ... Spiral grooves 6 ... Zoom operation ring (ring part)
7, 27 ・ ・ ・ Cam follower for guide (first cam follower)
8 ... Cam follower for cam groove (optical axis direction positioning member)
25 ・ ・ ・ Male helicoid (optical axis direction positioning member)
26 ... Female helicoid (ring part)

Claims (5)

A fixed cylinder having multiple helical grooves,
A movable barrel with the disposed inside the fixed cylinder, a plurality of first cam follower engaging with each of said plurality of helical grooves,
Arranged on the outer peripheral side of the fixed cylinder, and a rotatable ring portion ;
An optical axis direction positioning member that is slidably engaged with the ring portion and is fixed to the movable cylinder;
With
Position in the optical axis direction of the moving cylinder is determined by the rotational position of the ring portion,
A lens device.   The lens device according to claim 1, wherein the ring portion includes a cam groove, and the optical axis direction positioning member includes a second cam follower slidably engaged with the cam groove.   The ring portion includes a female screw portion of a female helicoid, and the optical axis direction positioning member includes a male screw portion of a male helicoid that slidably engages with the female screw portion. The lens device described.   4. The lens device according to claim 1, wherein the optical axis direction positioning member is configured integrally with one of the first cam followers. 5.   An imaging apparatus comprising: the lens apparatus according to claim 1; and an imaging element that receives a subject image by the lens apparatus.

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