JP2006003836A - Tilt adjusting mechanism for lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a tilt adjusting mechanism of simple constitution which does not require an adjusting washer as an another member, permits to adjust a tilt only by relative rotation between a lens frame and a holding frame, and permits to easily select a tilt adjusting direction. <P>SOLUTION: The tilt adjusting mechanism wherein counter diameter-directional faces which are perpendicular to the optical axis and faced to each other are formed on the lens frame for fixing a lens and the holding frame thereof, respectively, and the lens frame and the holding frame are biased in such a direction that the counter diameter-directional faces are brought into contact with each other, and wherein a pair of convex part and concave part are formed on one and the other of the counter diameter-directional faces, and the convex and concave parts of these counter diameter-directional faces closely adhere to each other in the state in which both are fitted with each other, and the lens frame is tilted against the holding frame while the convex part is in contact with the counter diameter-directional face on the side having the concave part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a tilt adjustment mechanism for a lens (system).

  As one of the adjustments of the lens system, there is a tilt adjustment for tilting the optical axis of the constituent lens (group) with respect to the optical axis (reference axis) of the entire lens system. Conventionally, this tilt adjustment is performed by, for example, forming a radially opposed surface on a lens frame that fixes one or more lenses and a holding frame that holds the lens frame, and at a specific position in the circumferential direction of the radially opposed surface. This was done by inserting a tilt adjustment washer. After the tilt adjustment, the lens frame and the holding frame are screwed or bonded and fixed.

  However, the tilt adjustment by the tilt adjustment washer is difficult to handle a small washer as a separate member, and the workability is very poor.

  The present invention provides a tilt adjustment mechanism having a simple configuration that does not require an adjustment washer as a separate member, can perform tilt adjustment simply by relative rotation between the lens frame and the holding frame, and can easily select the tilt adjustment direction. With the goal.

  In the lens tilt adjustment mechanism of the present invention, the lens frame to which the lens is fixed and the holding frame each have opposed radial surfaces that are orthogonal to the optical axis, and the lens frame and the holding frame are opposed to each other. The convex portion and the concave portion that form a pair on one and the other of the opposite radial surface are formed, and the convex portion and the concave portion of the opposite radial surface are fitted to each other. The lens frame is tilted with respect to the holding frame in a state where the opposed radial surface is in close contact and the convex portion is in contact with the opposed radial surface on the side having the concave portion.

  The biasing means can be simply constituted by a coil spring. Alternatively, the lens frame and the holding frame are each formed with an opposing cylindrical surface at the center of the optical axis, and the urging means is passed between the pair of opposed annular grooves formed on the opposed cylindrical surface and the pair of opposed annular grooves. It can comprise from the inserted C-shaped elastic ring member.

  It is practical that the holding frame is screwed into the lens moving cylinder, and the position of the lens moving cylinder in the optical axis direction can be adjusted by the screwing amount.

  According to the tilt adjustment mechanism of the present invention, when the tilt adjustment is unnecessary, the lens frame and the holding frame are not relatively rotated, and when the tilt adjustment is necessary, the lens frame and the holding frame are relatively rotated to adjust the tilt. The tilt direction can be selected by selecting the rotation angle.

  First, the entire structure of the zoom lens barrel to which the lens tilt adjustment structure of the present invention is applied will be described with reference to FIGS. The optical system of the zoom lens barrel is a four-group zoom lens system having a first lens unit L1, a second lens unit L2, a third lens unit L3, and a fourth lens unit L4 in order from the object side. The group L1 to the third lens group L3 are lens groups that are involved in zooming, and the fourth lens group L4 is a focus lens group that compensates for focal movement accompanying zooming and is involved in focusing.

  The stationary (fixed) members of the zoom lens barrel are a CCD holder 11, a housing 12 fixed in front of the CCD holder 11, and a rotation restricting ring 13 fixed at the tip of the housing 12. A CCD 11a and a fourth group rectilinear guide 11b are fixed to the CCD holder 11, and a fourth group frame 14 to which a fourth lens group L4 is fixed is guided linearly in the optical axis direction to the fourth group rectilinear guide 11b.

  The housing 12 is formed with a female helicoid 12a and a rectilinear guide groove 12b parallel to the optical axis on the inner peripheral surface thereof. The male helicoid 15a on the outer periphery of the rear end of the cam ring 15 is screwed into the female helicoid 12a. A flat gear 15b is formed on the mountain of the male helicoid 15a, and this flat gear 15b meshes with a pinion (not shown) of a forward / reverse drive motor 12c fixed to the housing 12. Accordingly, the cam ring 15 advances and retreats in the optical axis direction according to the helicoids 12a and 15a while the cam ring 15 rotates forward and backward by forward and reverse rotation of the forward and reverse drive motor 12c. In the zoom lens barrel, the cam ring 15 is the only rotating member.

  On the outer periphery of the cam ring 15, a straight guide ring 16 is bayonet-coupled so as to be relatively rotatable and move together in the optical axis direction. A rectilinear guide protrusion 16a that engages with the rectilinear guide groove 12b of the housing 12 is formed on the outer peripheral surface of the rectilinear guide ring 16. When the cam ring 15 rotates and advances and retracts in the optical axis direction, the rectilinear guide ring 16 is formed. While moving relative to the cam ring 15, it moves straight in the optical axis direction.

  A rectilinear guide groove 16b is formed on the inner peripheral surface of the rectilinear guide ring 16, and a rectilinear guide protrusion 17a formed on the rear end of the outer peripheral surface of the first group moving cylinder 17 is engaged with the rectilinear guide groove 16b. The first group moving cylinder 17 is composed of an inner and outer double cylinder whose front end portions are coupled by a radial wall, and the cam cylinder portion of the cam ring 15 is located between the inner cylinder and the outer cylinder. Further, a barrier support cylinder 18 is located between the linear guide ring 16 and the first group moving cylinder 17, and a linear guide protrusion (not shown) protruding from the inner peripheral surface of the barrier support cylinder 18 is provided. The first group moving cylinder 17 is fitted in the straight guide groove 17b. A barrier block 18 a is fitted and supported at the tip of the barrier support cylinder 18.

  A second group moving frame 19 is linearly guided in the optical axis direction on the inner peripheral surface of the first group moving cylinder 17, and the third group that supports the third lens group L3 and the shutter block 20a on the second group moving frame 19 is supported. The moving frame 20 is guided straight ahead. The first group moving cylinder 17 supports a first group frame 171 with a first lens group L1 fixed thereto, and the second group moving frame 19 has a second group frame 19a with a second lens group L2 fixed thereto by screwing. .

  The linear guide relation described above is such that the linear guide ring 16 is linearly guided to the housing 12, the first group moving cylinder 17 is guided linearly to the linear guide ring 16, the barrier support cylinder 18 and the second group moving frame 19 are guided to the first group movable cylinder 17. Is guided in a straight line, and the third group moving frame 20 is guided to the second group moving frame 19 in a straight line.

  Cam grooves C2 and C1 for the first group moving cylinder 17 and barrier support cylinder 18 are formed on the outer peripheral surface of the cam cylinder portion of the cam ring 15, and the second group moving frame 19 and third group are formed on the inner peripheral surface. Cam grooves C3 and C4 for the moving frame 20 are formed. The first group moving cylinder 17, the barrier support cylinder 18, the second group moving frame 19, and the third group moving frame 20 have followers 17f, 18f, 19f, and 20f that engage with the cam grooves C1, C2, C3, and C4, respectively. It is fixed or formed. As described above, the first group moving cylinder 17, the barrier support cylinder 18, the second group moving frame 19 and the third group moving frame 20 are all guided in a straight line. When the cam ring 15 rotates, the light follows the respective cam profiles and followers. By moving linearly in the axial direction, a zooming operation and a storing operation are performed. The fourth group frame 14 (fourth lens group L4) is driven in the optical axis direction by a stepping motor 12d fixed to the housing 12 based on focal point movement information and subject distance information accompanying zooming.

  The lens tilt adjustment mechanism of the present embodiment is applied to the first lens unit L1 supported by the first group moving cylinder 17 of the zoom lens barrel having the above-described configuration, and FIGS. The form is shown. The first lens unit L1 is fixed to the lens frame 171 by means such as adhesion or (thermal) caulking. A holding frame 172 is interposed as an intermediate cylinder member between the lens frame 171 and the first group moving cylinder 17. The first group moving cylinder 17, the lens frame 171 and the holding frame 172 all have a rotationally symmetrical shape around the optical axis as a basic shape.

  The holding frame 172 has a male screw 172 m on its outer peripheral surface that is screwed with a female screw 17 d formed on the inner peripheral surface of the first group moving cylinder 17. The holding frame 172 has a large-diameter recess 172a, a small-diameter recess 172b, and a radial surface 172c connecting the large-diameter recess 172a and the small-diameter recess 172b on the inner periphery thereof. On the other hand, the lens frame 171 has a large-diameter portion 171a, a small-diameter portion 171b corresponding to the large-diameter recess 172a, small-diameter recess 172b, and radial surface 172c, and a radial surface 171c connecting the large-diameter portion 171a and the small-diameter portion 171b. have.

  The large-diameter portion 171a of the lens frame 171 and the large-diameter concave portion 172a of the holding frame 172 are opposed cylindrical surfaces facing each other centering on the optical axis, and the radial surface 171c and the radial surface 172c are orthogonal to the optical axis. Radial surfaces facing each other. The large-diameter portion 171a and the large-diameter concave portion 172a are respectively formed with annular grooves 171d and 172d facing each other. A metal C-shaped elastic ring member 174 is inserted between the annular grooves 171d and 172d. Due to the elasticity of the C-shaped elastic ring member 174, the radial surface 171c and the radial surface 172c are formed. The lens frame 171 and the holding frame 172 are urged to move so as to contact each other (or so that the positions of the annular grooves 171d and 172d coincide with each other in the optical axis direction).

  On the radial surface 171c and the radial surface 172c, corresponding convex portions 171f and concave portions 172f (FIG. 4) are formed at one place in the circumferential direction. The convex portion 171f and the concave portion 172f do not hinder the close contact between the radial surface 171c and the radial surface 172c in a state in which both are fitted, and therefore the axes of the lens frame 171 and the holding frame 172 coincide (or are kept parallel). (FIG. 2).

  On the other hand, in a state where the convex portion 171f is in contact with the radial surface 172c, the axis of the lens frame 171 and the axis of the holding frame 172 are tilted. That is, if the axis of the holding frame 172 is used as a reference (the optical axis of the entire lens system), the axis of the lens frame 171 (that is, the optical axis of the first lens unit L1) is inclined with respect to the optical axis of the entire lens system ( FIG. 1). The direction of the tilt can be changed by changing the relative rotational position with respect to the holding frame 172 (changing the contact position of the convex portion 171f with respect to the radial surface 172c in the circumferential direction). The C-shaped elastic ring member 174 is not detached from between the annular grooves 171d and 172d during the above tilt adjustment, and is held with the lens frame 171 in a direction in which the radial surface 171c and the radial surface 172c come into contact with each other. The frame 172 is moved and energized. The relative rotation of the lens frame 171 with respect to the holding frame 172 can be performed by using a crimping groove 171g (FIG. 3) formed at a position opposite to the lens frame 171 at 180 °.

  In the zoom lens barrel of FIGS. 6 to 9, the first lens unit L1 and the second lens unit L2 are also adjusted in position in the optical axis direction for zoom adjustment. This zoom adjustment is performed by rotating the holding frame 172 relative to the first group moving cylinder 17 by using a squeezing groove 172g (FIGS. 3 and 4) formed at a position opposite to the holding frame 172 by 180 °, and screw 172m (17d ), The holding frame 172 can be moved in the optical axis direction.

  In the embodiment of FIGS. 1 to 4, the lens frame 171 and the holding frame 172 are moved and urged by the elasticity of the C-shaped elastic ring member 174 in the direction in which the radial surface 171 c and the radial surface 172 c are in contact with each other. There is a degree of freedom for the biasing means. FIG. 5 shows an embodiment in which the lens frame 171 and the holding frame 172 are moved and urged in the same direction by a compression coil spring (conical coil spring) 180.

  The zoom lens barrel described with reference to FIGS. 6 to 9 is an example to which the lens tilt adjustment structure of the present invention is applied, and it is apparent that the present invention can be applied to other lens systems (lens barrels).

It is a longitudinal cross-sectional view of the tilt adjustment state which shows one Embodiment of the tilt adjustment mechanism of the lens by this invention. It is a longitudinal cross-sectional view of the state where the tilt adjustment is not performed. It is the same exploded perspective view. It is a perspective view of the holding frame simple substance. FIG. 5 is a longitudinal sectional view showing another embodiment of a lens tilt adjusting mechanism according to the present invention, in which the urging means is constituted by a coil spring. It is a disassembled perspective view which shows an example of the zoom lens barrel which applies the tilt adjustment mechanism by this invention. FIG. 7 is an upper half sectional view of the zoom lens barrel of FIG. FIG. 7 is an upper half sectional view at a short focal length end of the zoom lens barrel of FIG. 6. FIG. 7 is an upper half cross-sectional view of the zoom lens barrel of FIG. 6 at a long focal length end.

Explanation of symbols

17 Group 1 moving cylinder 17d Female thread 171 Lens frame 171a 172a Large diameter part (opposing cylindrical surface)
171c 172c (opposite) radial direction surface 171d 172d annular groove 171f convex part 171g 172g cramp groove 172 holding frame 172f concave part 172m male thread 174 C-shaped elastic ring member (biasing means)
180 Compression conical coil spring (biasing means)
L1 First lens group (lens)

Claims (4)

A lens frame with a fixed lens,
A holding frame for holding the lens frame;
Formed on the lens frame and the holding frame, respectively, opposed radial surfaces orthogonal to the optical axes facing each other;
An urging member that urges the lens frame and the holding frame in a direction in which the opposed radial direction surfaces come into contact;
A pair of convex and concave portions formed on one and the other of the opposed radial surfaces,
With
The convex portion and the concave portion of the opposed radial surface are in close contact with each other when the two are fitted, and the convex portion is in contact with the opposed radial surface on the side having the concave portion with respect to the holding frame. A tilt adjustment mechanism for a lens, wherein the lens frame is tilted. 2. The lens tilt adjusting mechanism according to claim 1, wherein the biasing means is a coil spring. 2. The lens tilt adjusting mechanism according to claim 1, wherein each of the lens frame and the holding frame is formed with an opposing cylindrical surface at the center of the optical axis, and the biasing means is a pair formed on the opposing cylindrical surface, respectively. The tilt adjustment mechanism of the lens which consists of a C-shaped elastic ring member inserted across the annular grooves facing each other and the pair of opposed annular grooves. The lens tilt adjustment mechanism according to any one of claims 1 to 3, wherein the holding frame is screwed into the lens moving cylinder, and the position in the optical axis direction with respect to the lens moving cylinder is adjusted by the screwing amount. Lens tilt adjustment mechanism that is possible.

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