JPS62112110A - Device for energizing cam pin of zoom lens - Google Patents

Abstract

PURPOSE:To miniaturize a moving cylinder by using the peripheral side face of a lens to be held to the moving cylinder studded with cam pins as a rest for energizing springs. CONSTITUTION:The peripheral side face of of the zoom lens of which the cam pins are energized by the springs and which is held to the moving cylinder studded with the cam pins is used as the rest for the energizing springs. Holes 7 of the moving cylinder 5 for housing the cam pins 3 and the coil springs 6 are formed as through-holes and the coil springs 6 are formed as through-holes and the coil springs 6 are received by the peripheral side face L1 of the lens L1 and therefore, the outside diameter of the moving cylinder is reduced by as much as the wall thickness l3 of the moving cylinder.

Description

Detailed Description of the Invention A1 Object of the Invention [Field of Industrial Application] The present invention is a zoom lens for an optical machine such as a camera, which fits into a cam groove of a cam barrel and transmits driving force to a movable barrel. This invention relates to a device that uses a spring to urge a working cam pin in the direction of a cam groove.

[Conventional technology]

The cam groove 2 of the cam Bt used in a zoom lens may be made by cutting (FIG. 10) or by molding.

In the case of a molded product, as shown in FIG. 9, the ridgeline of the cam groove 2 is tapered in consideration of mold removal. This also applies to the through-through t+W cam shown in FIG. 6, and to the inner non-through cam groove shown in FIG. 7, which aims to reduce the wall thickness of the cam cylinder and reduce its diameter. Therefore, the portion of the cam pin 3 that engages with the cam groove 2 is formed into a truncated cone shape.

Now, with such a tapered cam groove 2, due to component tolerances, and a linear cylinder 4 having a linear groove 41 for guiding the cam cylinder 1 and pin 3. If a slight play in the radial direction occurs in the cam pin 3 due to the fitting play in the diameter of the movable tube 5 to which the lens L is fixed, the gap Δ2 is much larger than the minimum necessary gap Δl, as shown in FIG. This occurs between the cam groove 2 and the cam pin 30, and this causes a problem in that the positional accuracy of the movable cylinder 5 is significantly lowered.

[Problem that the invention seeks to solve]

Therefore, as shown in FIG. 8, the cam pin 3 is always urged in the direction of pressing against the cam groove 2 by a coil spring 6.

Therefore, the movable cylinder 5 has a depth 1 necessary to prevent the cam pin 3 from falling, and a depth g necessary to accommodate the compression coil spring 6.
2 holes 7 are required, and the diameter 1 + 2 is generally much larger than the minimum thickness 3 required to hold the lens L of the movable barrel 5. Therefore, the outer diameter of the movable barrel 5 becomes large and the zoom This was a major obstacle to miniaturizing the mechanism. In addition, since the cam pin 3 and coil spring 6 are required at three locations at 120° intervals, problems such as increased parts cost and increased assembly man-hours have arisen.

None of these problems occur in the case of the machined cam groove 2a without a taper shown in Fig. 10, but on the other hand, the cost is much higher than that of a molded cam, and -] the process stability is poor and it is difficult to produce clay. Since it has many drawbacks such as poor performance, it was thought that a molded cam cylinder would be far more preferable if the above-mentioned problems could be solved.

In view of the above points, the present invention aims to utilize a molded cam cylinder, which is advantageous in all respects compared to a machined cam cylinder, by providing four biasing devices for the cam cylinder used in the molded cam cylinder. The purpose is

Summary: Structure of the Invention [Means for Solving Problems] The present invention provides a zoom lens in which a cam bin is biased by a spring with a force of 4=J, and a peripheral surface of the lens that is held in a movable barrel in which the cam bin is installed. This is a cam pin urging device characterized in that the cam pin is used as a receiver for the urging force.

[For production]

Since the circumferential side of the lens held by the movable barrel is used as a surface for receiving the cam bin biasing spring, the outer diameter of the movable barrel can be reduced.

(Embodiment) FIGS. 1 to 3 show embodiments of the present invention, and the same members as in FIG. 8 are represented by the same numbers.

In FIG. 1, the hole 7 for accommodating the cam bin 3 and coil spring 6 of the movable cylinder 5 of the conventional example shown in FIG.

As a result, the movable tube has a thicker wall compared to the conventional method (Fig. 8).
The outer diameter of the moving cylinder can be made smaller, and the housing depths of the cambin and spring (vertical 1 and vertical 2) can be made sufficiently thick as before.

FIG. 2 shows an example in which the circumferential side of the lens is further cut to form a spring receiving surface L2. In the case of a lens in which the effective beam diameter B changes in the optical axis direction, the peripheral surface of the lens can be cut to form a surface L2 for the spring support, as shown in Figure 2, and the movable tube It is possible to make the outer diameter of 5 much smaller than in the case of FIG.

In FIG. 3, a plate spring 6 (see FIG. 4) formed in an approximately arc shape is used instead of the coil spring 6 as a biasing spring. After wrapping the lens L around the movable tube 5 and fixing it thereon, the cam bottle 3 is inserted into the hole 7a from the outer periphery of the movable tube.

In this embodiment, the thickness 2' required for accommodating the spring can be made much thinner than the thickness 2' in the case of a coil spring, so the outer diameter of the movable cylinder can be made even smaller. In addition, since the spring 10 has a simple shape that is easy to process and is made of one part, the cost of the spring parts can be reduced significantly, and the compatibility is greatly improved.

Incidentally, in place of the substantially arc-shaped leaf spring 10, a substantially arc-shaped wire spring 10a shown in FIG. 5 may be used.

C. Effects of the Invention [2] As explained above, by receiving the spring for biasing the cam pin on the circumferential side of the lens, the outer diameter of the zoom lens can be significantly reduced.

Therefore, the only problem with cam cylinders that use molded cam grooves, which are said to be better in all respects than cam cylinders with machined cam grooves, is the need to bias the cam pin. This has a great effect in solving the above-mentioned problems and promoting further utilization of molded cam cylinders.

[Brief explanation of drawings]

Claims (1)

[Claims] (1) A zoom lens in which a cam pin is biased by a spring, characterized in that the circumferential side of the lens held in a movable tube in which the cam pin is implanted is used as a receiver for the biasing spring. Device.