JPH073372Y2 - Lens tilt adjustment mechanism - Google Patents

Description

[Detailed description of the device] [Industrial applications]

The present invention relates to a lens tilt adjusting mechanism. In particular, the present invention relates to a lens tilt adjusting mechanism that can finely adjust the tilt of the lens after it is built into the camera body.

[Prior art]

The lens system in the still camera, which is the premise of the present invention, is
When the cam ring formed on the cam ring rotatably provided on the outer periphery of the lens barrel comes into contact with the trochanter provided on the outer periphery of the lens barrel at three or more points, and the cam ring rotates, the trochanter cams. It is extended to a desired position while contacting the surface. Therefore, in order to stabilize the optical axis of the lens system in such a lens driving mechanism, it is required that the position of the cam ring be accurately adjusted. Generally, the side surface of the subject of the shutter base plate is used as the reference surface and the end surface of the cam ring is adjusted. The cam ring is pressed against the reference surface to stabilize the cam ring. By the way, in the case of the known single focus lens,
Since the relationship between the lenses that make up the lens system is fixed, it is easy to maintain the assembly accuracy of the lens system, and because the lens drive mechanism has a relatively simple structure and there is space, the cam ring and shutter base plate A large effective contact area can be secured, and it is possible to sufficiently suppress the tilt of the optical axis within the allowable range by simply pressing the end surface of the cam ring against the subject side surface of the shutter base plate as in the conventional case. However, when a multifocal lens or a zoom lens, which has been widely used in recent years, is mounted, it is difficult to maintain the lens assembly accuracy because the lens system configuration is complicated. Since the lens drive mechanism has a complicated structure such as the lens operates independently, and the space margin is reduced, it is not possible to increase the effective contact area between the cam ring and the shutter base plate. There is a problem that it is difficult to keep the tilt of the optical axis within the allowable range simply by pressing the shutter to the subject side surface of the shutter base plate. Therefore, it is necessary to easily finely adjust the tilt of the lens after the lens is assembled. The advent of a lens tilt adjusting mechanism capable of achieving this has been desired.

[Means for solving problems]

The present invention has been made in response to such a demand, and an object thereof is to provide a lens tilt adjusting mechanism capable of easily adjusting the tilt of the optical axis of the lens after the lens is assembled. That is, the lens tilt adjusting mechanism of the present invention is as follows: A cam ring is rotatably arranged along the outer circumference of a lens barrel incorporating a lens system, and the lens barrel is driven by a cam surface formed on the cam ring. On the premise of a lens driving mechanism which is configured so that the cam ring and the lens barrel can be integrally tilted in the optical axis direction while moving in the optical axis direction: the cam ring is attached to the object direction through the lens barrel. Providing a biasing spring:
Providing three contact points for supporting the subject-direction biasing force applied from the spring to the cam ring from the subject side: at least two of the three contact points are movable in the lens feeding direction. At the same time, the movable operating portion at the movable contact point is provided at a position operable from the subject side.

[Action]

That is, in the lens tilt adjusting mechanism of the present invention, the lens barrel is extended by following the cam surface formed on the cam ring. Therefore, the tilt angle of the optical axis of the lens is finely adjusted by adjusting the mounting angle of the cam ring. To be done. Since the cam ring is biased toward the subject and the biasing force is supported at the three contact points, the cam ring is positioned with the subject-side surface including the three contact points as the reference plane.
By appropriately moving two of the three contact points in the lens feeding direction, the angle of the reference plane supporting the cam ring is arbitrarily adjusted, and the optical axis angle of the lens is also adjusted. Further, since the cam ring is biased toward the subject and is supported from the subject side, the position of the contact point can be adjusted from the front side of the lens. The present invention can be applied even to a lens whose optical axis is difficult to maintain, such as a multifocal lens or a zoom lens, and thus can be naturally applied to a single focus lens whose optical axis can be easily maintained.

【Example】

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. First, FIG. 1 is a front view showing the lens tilt adjusting mechanism of the present invention with the lens system and front plate removed.
The drawing is a sectional view of FIG. 1 taken along line XY. In the drawings, 1 is a shutter base plate on which a shutter mechanism (not shown) is mounted, and 2 is an upper base plate fixed to the front surface (subject side) of the shutter base plate 1. The upper base plate 2 is formed in a substantially ring shape, and the cam ring 3 is rotatably held along the inner peripheral surface of a hole 2a formed in the central portion of the upper base plate 2. A lens barrel 5 incorporating a lens system 4 is inserted into the inner peripheral surface 3a of the cam ring 3, and the rear end surface (end surface on the film surface side) of the lens barrel 5 is an aperture 1a formed in the center of the shutter base plate 1. An urging force in the direction of the subject is received from the coil spring 6 arranged on the outer periphery of the. A plurality of trochanters 5a are provided so as to project on the outer peripheral portion of the lens barrel 5,
The trochanter 5a is in contact with the cam surface 3b formed in a slope shape on the film surface side on the inner circumference of the cam ring 3, and the lens barrel 5 is extended by the rotation of the cam ring 3. Next, a hook-shaped contact portion 2b is formed at an arbitrary position on the inner peripheral portion of the upper base plate 2 so as to wrap around the tip end surface (end surface on the object side) of the cam ring 3. Further, a fan-shaped pressing plate 7 is fitted and fixed to the front surface of the upper base plate 2 with the bosses 2c, 2d and 2e.
The pressing plate 7 has elasticity in its material and its arm portion
An abutting portion 7c in which the tips of 7a and 7b are respectively bent in a crank shape and abut the tip surface of the cam ring 3. Forming 7d. Further, desirably, the abutting portion 2b and the abutting portions 7c and 7d each have an interval of approximately 120 °, and support the tip end surface of the cam ring 3 at three points. Further, a ring-shaped front plate 8 is fixed to the front surface of the cam ring 2, and the tips of the screws 9a, 9b screwed onto the front plate 8 are in contact with the arms 7a, 7b of the pressing plate 7. Since the lens tilt adjusting mechanism of this embodiment is constructed as described above, it operates as follows. First, the lens barrel 5 is constantly urged toward the subject by the coil spring 6, but its trochanters 5a and 5b come into contact with the cam surface 3b formed on the cam ring 3, and the tip surface of the cam ring 3 is Since it is supported at the three contact points 2b, 7c, 7d, the extension of the lens barrel 5 is restricted at that position. In this state, when the sum ring 3 is rotated along the inner peripheral surface 2a of the upper base plate 2 by an actuator (not shown) such as a step motor or a spring, the lens barrel 5 is urged by the spring 6 and its trochanters 5a and 5b. Is driven by the cam surface 3b formed on the cam ring 3, so that the lens barrel 5 is extended toward the subject, and when the rotation of the cam ring 3 is stopped, the above-mentioned extension operation is also stopped. Since the center line of the lens barrel 5 (that is, the optical axis of the lens system 4) coincides with the center line of rotation of the cam ring 3, the center line of rotation of the cam ring 3 is adjusted so as to be orthogonal to the film surface (not shown). By doing so, it is possible to adjust the inclination of the optical axis of the lens system 4. In this embodiment, the cam ring 3 is biased toward the subject by the coil spring 6 via the lens barrel 5 and Since the tip surface is supported at three points of the contact parts 2b, 7c, 7d, the center line of rotation of the cam ring 3 is the contact parts 2b, 7c, 7d.
It will be orthogonal to the plane including 3 points of 7d. Of the three contact portions 2b, 7c, 7d, the contact portions 7c, 7d are formed at the tips of the arm portions 7a, 7b of the elastic pressing plate 7, and the arm portions 7a, 7b have Screws each screwed to the front plate 8
Since the tips of 9a and 9b are in contact, the planes including the three points of the contact portions 2b, 7c and 7d can be freely adjusted by rotating the screws 9a and 9b to the right and left respectively. Therefore, if the planes including the three points of the contact portions 2b, 7c, and 7d are adjusted by rotating the screws 9a and 9b to the right and left respectively as described above, the center line around which the cam ring 3 rotates and the film surface are adjusted. It is possible to freely adjust the orthogonality with respect to, that is, the inclination of the optical axis of the lens system 4. It should be noted that the lens tilt adjusting mechanism of this embodiment is provided with the cam ring 3
Is a lens drive mechanism having a structure in which is biased toward the subject and the biasing force is supported from the subject side, the structure of the actuator for applying the rotational force to the cam ring 3 is not particularly limited. . Further, in the above, the tip end surface of the cam ring 3 is attached to the contact portion 2b.
Although the example in which the support is provided by 7c and 7d is shown, as long as the structure is such that the biasing force applied to the cam ring 3 in the direction of the subject is supported from the subject side, for example, a groove is formed along the outer periphery of the cam ring 3. Alternatively, the groove portion may be formed and supported at three points.

【effect】

As described above, in the present invention, since the cam ring is supported from the subject side, it is possible to adjust the tilt of the lens from the front side of the taking lens after the lens system is assembled. Even in the case of a lens in which it is difficult to maintain the orthogonality of the optical axes, it becomes easy to maintain the inclination within the allowable range.

[Brief description of drawings]

FIG. 1 is a front view showing the lens tilt adjusting mechanism of the present invention with the lens system and front plate removed, and FIG. 2 is a sectional view taken along line XY in FIG. 2 ... Top plate, 2b ... Contact surface 3 ... Cam ring, 3a ... Cam surface 4 ... Lens system, 5 ... Lens barrel 5a, 5b ... Roller, 6 ... Spring 7 ... Press plate , 7c, 7d …… Abutting surface 9a, 9b …… Screw

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-58-192004 (JP, A) Actually developed, JP-A-56-88215 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A cam ring is rotatably arranged along the outer circumference of a lens barrel incorporating a lens system, and the lens barrel moves in the optical axis direction by being driven by a cam surface formed on the cam ring. In a lens driving mechanism in which the cam ring and the lens barrel can be integrally tilted in the optical axis direction, a spring for urging the cam ring toward the subject through the lens barrel is provided. Three contact points for supporting the urging force applied to the cam ring in the direction of the object from the object side are provided, and at least two of the three contact points are movable in the lens extending direction. A tilt adjusting mechanism for a lens, wherein a movable operating portion at a movable contact point is provided at a position operable from the subject side.