JPS61246710A - Device for delivering lens - Google Patents

Abstract

PURPOSE:To reduce torque to be required for delivering of a lens and to assemble a compact device easily by arranging spheres siding on the inside of a guide cylinder on plural recessed parts formed on the periphery of a lens frame. CONSTITUTION:When the guide cylinder 19 is rotated around a cam cylinder 30 and the side of a cam groove 31 is abutted on a cam follower 32, the cam follower 32 is pressed against the circumferential direction and simultaneously abutted on the side of a guide groove 20, so that component force for energizing the cam follower 32 in the optical axis direction by the inclination of the cam groove 20 is applied to the cam follower 32. Since the lens frame 23 is fixed on a screw 33 for supporting the cam follower 32, the lens frame 23 is also energized in the optical axis direction. The lens frame 23 is engaged with the guide cylinder 19 through the spheres 29, the lens frame 23 is easily delivered in the optical axis direction on the basis of the rotation of the spheres 29. Two spheres 29 each are arranged in the optical axis direction, so that the lens frame 23 can be engaged with the guide cylinder 19 without being inclined from the optical axis.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to a lens feeding device that can vary the distance between lenses, such as a variable focus camera or a zoom lens.

2. Description of the Related Art Conventionally, there is a method for extending a lens by changing the rotational movement in the axial direction of the lens barrel into the movement in the optical axis direction by engaging helicoidal screws or guiding by a cam groove. In particular, the method using a cam is often used in zoom systems that require complex operations because the rotation angle of the cam barrel and the amount of lens extension can be arbitrarily selected. FIG. 2 is a simplified exploded perspective view of the lens extending mechanism of a typical zoom lens system. The main body 1 is a tube with a cutout hole 2 on the side and is fixed to a camera body (not shown).
A cam cylinder 4 having a cam groove 3 is fitted inside the main body, and a guide ball 6.6' is inserted through the inside of the cam cylinder.
One end of is fixed. The guide ball 6 fits into the hole 8 of the sleeve 7 of the lens frame e, and the guide ball 6' engages with the notch 9 of the lens frame 6 to support the lens frame e so as to be movable in the optical axis direction. Hole 11 of guide pole support plate 10,
11' and fastened by the oak 12 and 12'.

The guide pole support plate 1o is fixed to the main body 1 by another means. 13 is a lens to be fixed to the lens frame 6. The lens frame 6 supported by the guide balls 6 and 6' is
A cam follower 15, which engages with the cam groove 3 at a position where the cam follower attachment hole 14 matches the cam groove 3, is fixed to the cam follower attachment hole 14 with a screw 16, thereby establishing a dynamic connection with the cam cylinder 4. The cam cylinder 4 is fixed to a mounting hole 17 provided at a position corresponding to the notch hole 2 of the main body 1 with a follower (not shown) that engages with the notch hole 2, thereby preventing movement in the optical axis direction with respect to the main body. is regulated, allowing rotation around the optical axis within a predetermined range.

When the cam cylinder 4 is rotated with the above configuration, the cam follower 16
Power is transmitted to the lens frame 6, and a force that tries to rotate is also applied to the lens frame 6, but since the guide poles 5 and 6' are fastened to the main body, the lens frame does not rotate and is suppressed by the guide poles 5 and 5'. . At this time, the cam follower 16 is also pressed against the cam surface 18 of the cam groove 3 of the cam cylinder 4. As a result, a component force in the optical axis direction is generated due to the inclination of the cam groove, and the lens frame 6 is urged in the optical axis direction. At this time, the lens frame 6 is moved in the optical axis direction by a force that is the sum of the friction force between the hole 8 of the sleeve 7 of the lens frame 6 and the guide pole 6 in the suppressed state, and the friction force between the notch 9 and the guide pole 61 in the press state. If the urging force is large, the lens frame 6 will be extended in the optical axis direction.

Generally, a zoom lens group is divided into two groups, each of which moves differently, so adding one more guide pole,
The number of cam grooves and lens frames is also increased by one, and two lens frames are driven at the same time by the rotation of the cam barrel, but one is omitted because the principle is the same.

The problem that the invention aims to solve The above configuration has the following problems.

■ The lens extension torque increases. That is, as is clear from the above description, since a force is required to overcome the friction between the guide pole 6 and the lens frame, the required torque for rotating the cam barrel 4 becomes large. In particular, if the point of force that presses the cam follower and the two friction surfaces are far apart, the rigidity of the lens frame will cause deformation and the torque will further increase.

■ Since it is necessary to provide the sleeve 7 and the notch 9 in the lens frame, only lenses that are considerably smaller than the size of the lens frame can be accommodated.

Therefore, the entire lens feeding mechanism becomes large.

■ The guide pole that guides the lens frame can only be securely fixed after the lens frame and guide pole support plate are assembled, so when assembling the lens frame, it is difficult to determine the position of the tip of the guide pole, and the lens Assembling the frame is difficult.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a lens feeding device that requires small torque for lens feeding, is compact, and is easy to assemble.

Means for Solving the Problems The technical means of the present invention for solving the above problems is to arrange spheres that slide on the inner surface of the guide tube in a plurality of recesses provided on the outer periphery of the lens frame. , a guide groove along the optical axis direction of the guide tube and an engaging member that engages with the cam groove of the cam tube are supported on the lens frame.

For production The effect of this technical means is as follows.

In other words, when the cam cylinder is rotated, the engaging member is urged in the rotational direction, but since the guide groove only allows movement in the optical axis direction, it is pressed against the inclined surface of the cam surface and moves in the optical axis direction. Gain power. At this time, since the lens frame is fitted to the guide tube through the sphere, it can move freely in the optical axis direction of the guide tube, so that it can be easily extended in the optical axis direction.

Embodiment Hereinafter, an embodiment of the present invention will be described based on the accompanying drawings. In FIG. 2, which is an exploded perspective view, 19 is a part of the guide tube to be attached to the camera body and other lens units (both not shown), and there is a guide tube along the optical axis A-A/ on the side. The groove 2o and the inner surface 21 also have three grooves 22 along the optical axis. The lens frame 23 is to be housed inside the guide tube 19, and has a circumferential direction 3 on the outer periphery.
The engagement part 2 has a total of six recesses 24 and one engagement screw hole 26, two in the optical axis direction, and has an engagement part 2 on the inner periphery that engages the lens 26 and the lens support ring 27.
8 is provided. When the guide groove 2o of the guide tube 19 and the engagement screw hole 26 of the lens frame 23 match, the guide tube 1
The groove 22 of the guide tube 19 and the recess 24 of the lens frame 23 are in such a positional relationship that the groove 22 of the guide tube 19 and the recess 24 of the lens frame 23 are in such a position that the depth of the groove 22 and the recess 24 of the lens frame 23 are such that the sphere 29 fits perfectly. Dimensions are provided. FIG. 3 is a partial perspective view of the lens frame and guide tube in the assembly process, shown to make it easier to understand the assembled state of the lens frame 23 and guide tube 19 in FIG. While pressing the sphere 29 against the groove 24, the groove 22 between the sphere 29 and the guide tube 19
By entering the lens frame 23 into the guide tube 1e so that the engagement screw holes 25 and the guide grooves 2° coincide with each other, the two are fitted through the spheres while maintaining the positional relationship in which the engagement screw holes 25 and the guide grooves 2° coincide with each other. do. 30 in FIG. 1 is a cam cylinder, and a cam cylinder 3o is provided with a cam groove 31 on the side surface that is inclined with respect to the optical axis.
The guide tube 19 is regulated in the optical axis direction and rotatably fitted in the circumferential direction. The cam barrel is rotated until the cam groove 31 matches the guide groove 2o and the engagement screw hole, and the cam follower 32, which is an engagement member, is fitted into the cam groove 31 and the guide groove 20, and the screw 33 is inserted into the cam follower 32. The cam follower 3 is inserted through the hole 34 and screwed into the engagement screw hole 26 of the lens frame.
2 to the lens frame.

In the above configuration, by rotating the cam barrel 3o with respect to the guide barrel 19, the side surface of the cam groove 31 and the cam follower 32
contact, and the cam follower 32 is pressed in the circumferential direction. However, since the cam follower 32 is also in contact with the side surface of the guide groove 20 at the same time, the cam follower 32 receives a component force that urges it in the optical axis direction due to the inclination of the cam groove 20. obtain. At this time, since the lens frame 23 is fixed to the screw 33 that supports the cam follower 32, it is urged in the optical axis direction. Since the lens frame 23 is fitted to the guide cylinder 19 via the sphere 29, it is easily extended in the optical axis direction by the rolling of the sphere 29.

Since the spheres 29 are arranged at two locations in the optical axis direction, the lens frame 23 can be fitted into the guide tube without being tilted with respect to the optical axis.

In the embodiment described above, the groove 22 of the guide tube 19 is provided to maintain a matching relationship between the guide groove 2o and the engagement screw hole 25 during assembly, and when the assembly is completed, the guide groove 2o and the cam follower 32 are This is not necessarily necessary since axial guidance is provided, but it is convenient when fitting the cam follower 32 while keeping the cam groove 31, guide groove 20, and engagement screw hole 26 in the same relationship.

Therefore, without providing the groove 22 on the inner surface 21 of the guide tube 19, the inner surface 21 is left as a cylindrical surface, and the guide groove can be fitted at 20 degrees, which is advantageous when it is desired to minimize the inclination of the lens. .

In addition, if the cam follower that engages with the cam groove 31 and the cam follower that engages with the guide groove are separate members and are provided so as to be rotatable relative to a fixed member such as a screw that supports the lens frame, the cam groove Since the cam follower that engages with the guide groove always receives a rotational force opposite to that of the cam follower that engages with the guide groove, each generates rolling friction against the groove side surface, resulting in the effect of further reducing the rotational torque.

The lens extending mechanism according to the present invention can be used without being limited to a focusing mechanism, a zoom mechanism, etc.

Effects of the Invention The present invention has a lens frame that is extended by rolling friction, so there is little energy loss due to the extension, and it can be driven with low torque and can be used as a power zoom lens, power focus lens, autofocus lens, etc. using a battery as a power source. Particularly advantageous.

Furthermore, the present invention does not require guide balls, guide ball support plates, sleeves formed in the lens frame, cutouts, etc., so it is not only advantageous in terms of cost but also advantageous in terms of space. If so, the diameters of the cam tube and guide tube can be reduced, which is advantageous for downsizing the camera.

Furthermore, there is no need to attach the lens frame to items such as guide balls whose tip position cannot be determined during assembly, and the lens system can be assembled simply by inserting the sphere while making contact with the lens frame. Increase productivity.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of a portion of a lens unit according to an embodiment of the present invention, FIG. 2 is an exploded perspective view of a portion of a conventional zoom lens system, and FIG. 3 is an exploded perspective view of a portion of a lens unit according to an embodiment of the present invention. FIG. 26...lens, 24...concavity, 23
・・・・・・Lens frame, 2o・・・Guide groove, 19
...Guide tube, 31...Cam groove, 3o.
...Cam tube, 32...Cam follower.

Claims (1)

[Claims] a lens frame having a lens fixed therein and having a plurality of concave portions on its outer periphery; a guide tube having a guide groove along an optical axis on a side surface;
The lens frame and the inner surface of the guide tube are fitted into each other through a plurality of spheres that engage with the recess, and the guide tube and the cam A lens feeding device in which a barrel is rotatably fitted and an engaging member that engages with the guide groove and the cam groove is supported on a lens frame.