JPH0442810Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention provides zoom optical system adjustment for zoom lenses of photographic and recording equipment such as video cameras, still cameras, copiers, and surveillance television. The present invention relates to an adjustment mechanism used for focus correction.

[Prior Art] Zoom optical system adjustment for the above-mentioned photography and recording equipment is generally performed by adjusting focus correction using a cylindrical cam barrel having a cam (lens spacing correction groove) in the barrel. In this mechanism, since it is first necessary to remove the play in the thrust direction that exists during the manufacture of the cam cylinder and the constituent members of this mechanism, a focus correction process is required for each product. Common known examples of this adjustment include:
Adjustment using a washer as shown in Figure 1,
Methods of adjustment include interposing a wave-shaped washer, interposing a washer and using an adjusting screw, or adjusting by increasing the machining accuracy of the component parts.

However, all of these methods involve adjustments based on empirical values. In addition, even after this adjustment, there were disadvantages in that torque fluctuations and play in the thrust direction occurred due to environmental changes. This point is particularly noticeable when different materials (plastic and metal) are used.

[Problems to be solved by the invention] In the invention, the front lens barrel main body 1, the cam barrel 2, and the restraining plate 4 are assembled, and the focus correction is adjusted to eliminate the axial play. The aim is to propose a new mechanism that can reduce torque fluctuations caused by environmental changes after adjustment, and automatically adjust focus correction for play in the thrust direction.

[Means for solving the problem] In the cam barrel adjustment mechanism of a lens barrel having a conventional zoom optical system, play is likely to occur particularly in the thrust direction.
As a result, the focal point shifts when zooming.

In order to solve the above problems, the present invention first has a sloped surface with a certain angle intersecting the optical axis on the end face of the cam barrel 2 on the camera mount side, and the gap between the sloped surface and the restraining plate 4 is An annular C spring 3 having an appropriate wire diameter and a special shape is interposed between the retainer plate 4 and the retainer plate 4 on the end surface of the front lens barrel body 1 so that the slope abuts against the plate surface of the retainer plate 4. This is an improved mechanism with a screwed structure using screws 5, 5, 5. A typical example is shown in FIG. 2A.

Next, the shape and other aspects of the C spring 3 play an important role in the mechanism of the present invention, as described in the embodiment section. That is, by adjusting the correction during manufacturing, reducing torque fluctuations caused by environmental changes after adjustment, and automatically adjusting the focus correction for the clearance in the thrust direction, it is useful to prevent focus deviation.

Since the surface on which the C spring 3 is attached is perpendicular to the optical axis, the amount of play displacement in the thrust direction appears as a play gap, and the C spring 3 is guided by the slope and the C spring 3 has a radial direction. As a result, the outer diameter of the C spring is expanded in the radial direction along the abutting slopes, or contracted and returned to its original size in response to changes in the displacement of the clearance in the thrust direction. It swells and displaces. Along with this, the play in the thrust direction is suppressed and eliminated, and the automatic focus correction adjustment is performed accordingly.

Further, the C spring 3 is annular in plan view and has an opening with an angle θ. Moreover, since both ends of the spring at the opening have a shape with staggered steps like a spring washer, in addition to the biasing elasticity in the thrust direction, it also pushes the spring in the radial direction to expand and restore its shape. Since it also acts as a biasing elastic force, it reduces torque fluctuations.

[Function] As is clear from the above means, according to the present invention, the C spring 3 interposed between the slope formed on the end surface of the cam cylinder 2 and the plate surface of the restraining plate 4 is moved in the radial direction by thrust. This generates biasing elasticity that acts on the shaft, making adjustment easier, reducing the number of adjustment steps during manufacturing, reducing torque fluctuations caused by environmental changes after adjustment, and reducing play in the thrust direction. It acts in the direction of inhibiting the abutment-guided slope, thereby making effective the adjustment of the automatic correction of the focus.

[Example] Hereinafter, a preferred example of this invention will be described in detail based on the accompanying drawings.

(1) FIG. 3 is an external perspective view showing an assembled state of the front lens barrel body 1 having a zoom optical system, a cam barrel 2, a restraining plate 4, etc. Fourth
The figure shows a cross section of the cam barrel adjustment mechanism of the lens barrel according to the present invention.

First, referring to FIG. 4, numeral 1 indicates the front lens barrel body, and numeral 2 indicates the cam barrel. The cam barrel 2 forms an outer barrel that fits onto the front barrel body 1, and lens interval adjustment grooves A and B (shown in FIG. 3) are bored on the side surface of the barrel, and It is a member having a diameter and a certain rotation angle with respect to one end face of the cam cylinder 2, and is equipped with a cam mechanism that allows the zoom lens to move the distance between the zoom lenses in the optical axis direction. The camera mount side of the cam barrel 2 is provided with an inclined surface having a certain angle that intersects with the optical axis. 3 is a C spring (details shown in Fig. 5), 4 is a restraining plate, and 5 is a screw.

A C spring 3 is interposed between the slope formed on the end surface of the cam barrel 2 and the plate surface of the restraining plate 4, and the restraining plate 4 is attached to the front lens barrel body 1 using screws 5, 5, 5. When screwing on the cam cylinder, adjust the thrust direction dimension l (shown in FIG. The C springs 3 are designed so that they collide and are guided, and stress is exerted on the C springs 3 in the outer diameter direction.

Further, when the thrust acts in the direction of the optical axis, the mechanism is such that its movement is suppressed by the restraining plate 4. Furthermore, torque fluctuations are determined by the stress acting in the radial direction of the C spring and are stabilized.

The amount of displacement of the play in the thrust direction caused by the machining and finishing conditions of the slope applied to the end face of the cam cylinder 2 and environmental conditions such as temperature and humidity is C.
The spring 3 abuts against and is guided by this slope, resulting in a change in the outer diameter of the C spring 3 corresponding to these conditions, meaning a radial displacement of Δl' with respect to l' (shown). As a result, the C spring 3 moves in balance with the displacement of the clearance in the thrust direction, and the focus correction is automatically adjusted.

Next, FIG. 5 shows the shape of the C spring 3, which has a circular cross section and has an annular angle θ in plan view.
It has an opening. When viewed from the side, both ends of this opening have staggered steps, just like spring washers. It promotes the biasing elasticity in the direction perpendicular to the plane of the C spring 3, that is, the biasing elasticity that acts in the thrust direction in the mechanism according to the present invention, and contributes to reducing torque fluctuations and adjusting the automatic correction of the focus. ing.

(2) In Figure 2, the example of the previous paragraph (1) is A in the figure.
B to D are shown as representative examples corresponding to the above, and as other embodiments. Embodiments B and C are similar to the typical embodiment A in that a C spring 3 is interposed between each end face of the cam cylinders 2, 2a and the restraining plate 4a, but the following points are added. The shapes are different.

A. The end face of the cam cylinder 2a is flat, and contrary to the case of the embodiment described in the previous item (1) (Fig. A), when the plate surface of the holding plate 4 is sloped (Fig. B), In the case where both the end face of the cam cylinder 2 and the plate face of the restraining plate 4 are provided with slopes that face each other in a figure-eight shape in cross section (C in the figure), there is a case where either of the above B and C is applied. In this case as well, an adjustment mechanism having basically the same function as described in item (1) of the above embodiment can be obtained.

In the case of illustration D, a spacer ring 6 which is cap-shaped and has long grooves bored in the longitudinal direction on its outer periphery is newly used, and a sloped surface made on the end face of the cam cylinder 2 in the same manner as in illustration A is used. A C spring 3 is interposed between the spacer ring 6 and the inner surface thereof. The side surface of the spacer ring 6 has a long groove formed in the axial direction, and by screwing the interlocking screw 7 onto the outside of the cam cylinder 2 through this long groove, the cam cylinder 2 is integrated. The end surface of the front lens barrel body 1 and the holding plate 4 are fitted onto the front lens barrel body 1.
It has a structure in which it is screwed together with screws 5, 5, 5.

As mentioned above, since the cam cylinder 2, C spring 3, and spacer ring 6 rotate integrally, there is no rotational slip of the spacer ring 6, and according to the present invention, the play in the thrust direction is reduced in the longitudinal direction of the outer circumference of the spacer ring. As a result, the cam cylinder is allowed to slide together with the interlocking screw 7 along the long groove drilled in the long groove within the range regulated by the length of the long groove. An adjustment mechanism with an adjustment function is obtained.

[Effect of the invention] In the adjustment according to the known general example as shown in FIG.
By using a washer, using the washer in combination with an adjustment screw, using a wave-shaped washer, or adjusting by methods such as increasing processing accuracy and determining dimensions, etc.
Even if it is possible to reliably eliminate the play in the thrust direction, this requires skilled technology and more man-hours than necessary for adjustment during manufacturing based on experience, and also changes in the environment. Because of the occurrence of torque fluctuations and play in the thrust direction after adjustment, it is troublesome and difficult that the amount of play displacement must be taken into consideration in advance. However, in the present invention, as described in the embodiment (Fig. 2), focus correction adjustment during manufacturing, reduction of torque fluctuation based on environmental changes after adjustment, and automatic correction of play in the thrust direction. This makes it possible to adjust the

As a result, it is possible to prevent the focus from shifting when using the camera, and the present invention exhibits the effect of contributing to improving the photographic effect. Furthermore, it is possible to reduce the number of adjustment man-hours required for adjusting the focus correction during manufacturing, rather than requiring more than necessary, and it can be expected that productivity will be improved and production costs will be reduced.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a known general example (A, B, C). FIG. 2 is a sectional view showing embodiments (A, B, C, D) as a mechanism according to the present invention. Third
The figure is a perspective view of the assembled state of the front lens barrel body, the cam barrel, the holding plate, screws, and other structural members. FIG. 4 is a sectional view of a typical embodiment of the present invention (FIG. 2A) showing a mechanism according to the present invention, which is attached with a C spring interposed therebetween. Figure 5 shows
It shows the shape of the C spring used in the example. 1... Front lens barrel body, 2, 2a... Cam barrel, 3
... C spring, 4, 4a ... holding plate, 5 ... screw,
6...Spacer ring, 7...Interlocking screw.

Claims (1)

[Claims for Utility Model Registration] (1) An annular spring is interposed between the end surface of the cam cylinder and the surface that abuts, and the surface that the spring abuts is sloped, so that after the focus is adjusted, A cam barrel adjustment mechanism for a lens barrel, characterized by having a mechanism that reduces torque fluctuations caused by environmental changes and automatically performs focus correction based on play in the thrust direction. (2) The end face of the cam barrel 2 on the camera mount side is provided with a slope having a certain angle that intersects the optical axis, and a C spring 3 is interposed between this slope and the restraining plate 4, so that the restraining plate 4 to the front lens barrel body 1 with screw 5
Utility model registration claim No. 1 (1) has a structure in which the screws are screwed together to reduce torque fluctuations after focus adjustment and to automatically adjust focus correction based on the play in the thrust direction. The cam barrel adjustment mechanism of the lens barrel described in item 1). (3) A utility model registration request in which a C spring 3 is interposed between the end surface of the cam barrel 2 opposite to the end surface on the camera mount side and the surface of the front lens barrel body 1 that is in contact with the end surface. The cam barrel adjustment mechanism of the lens barrel described in scope item (1).