JPH0244247Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a lens barrel having a lens moving device for focusing or changing magnification in a photographic lens.

<Prior art> Devices that use a cam tube to control the movement of a lens in the optical axis direction for focusing or variable magnification are known, but the main components of these devices have traditionally been made of metal materials. Ta. This type of metal material has the drawbacks of being expensive, requiring high processing costs, and being heavy.

In order to overcome these drawbacks, attempts are being made to use plastic materials.

<Problems that the invention aims to solve> By the way, the precision of molding plastic materials is inferior to the precision of metal processing, so there is no technology to eliminate the negative effects, and cams similar to those that can be made by metal processing have not been developed. Due to reasons such as the inability to form grooves using conventional techniques, a system in which all of the main components of the moving device are replaced with plastic molded products has not been realized.

Specifically, when cam grooves are molded from plastic material, a taper is formed in the cam groove due to problems with the mold, and as a result, it is difficult to make the cam follower follow the displacement of the cam groove without play. become.

The purpose of the present invention is to eliminate the drawbacks of the conventional example described above, and to provide a lens barrel that allows a cam follower to accurately follow even if two intersecting cam grooves have an inclination angle in the radial direction. shall be.

<Means to solve the problem> The present invention will be explained based on the drawings.

FIG. 1 shows a sectional view of a main part of a lens barrel equipped with a lens moving device according to the present invention.

The present invention has a cam groove 1a formed in a fixed cylinder 1.
A cam follower is inserted into the intersection of both cam grooves 2a and 2a formed in the cam barrel 2, and the moving lens is moved in the optical axis direction by the movement of the cam follower in the optical axis direction. The cam grooves 1a and 2a are respectively formed on inclined surfaces 1b and 2b having opposite inclination angles in the radial direction,
The cam follower is formed from two coaxial cam followers 4 and 5 that engage with both cam grooves 2a and 1a, respectively.
The surfaces in contact with the cam grooves 2 and 2 are formed to have an inclination angle equivalent to that of the cam grooves.
A spring 6 is provided to urge the two cam followers 4 and 5 to come into contact with the inclined surfaces 2b and 1b of a and 1a.

<Operation> Next, the operation will be explained. When the cam barrel 2 is moved forward and backward in the optical axis direction by an external operation ring (not shown), the guide pins 4 and 5 as cam followers rotate and rotate according to the intersection of the cam groove 1a of the fixed barrel 1 and the cam groove 2a of the cam barrel 2. It moves in the optical axis direction, and the movable lens frame 3 is moved back and forth in the optical axis direction.

By the way, when the cam grooves of the fixed barrel 1 and cam barrel 2 are molded from plastic material, the cam surfaces are inclined at an angle with the current technology. On the other hand, two cam grooves with different inclinations are required, and by arranging the guide pins that engage with these cam grooves coaxially, the number of holes penetrating the cam cylinder 2 is minimized, and the deformation of plastic molding is avoided. However, as mentioned above, it is practically difficult for the sloped surface of one guide pin to contact the two sloped cam groove surfaces at the same time due to the lack of precision in plastic molding. As in the present invention, two guide pins 4 and 5 are arranged coaxially, and one spring 6 simultaneously attaches the pins 4 and 5 to the inclined surface 2b of the cam groove 2a and the inclined surface 1b of the cam groove 1a, respectively. The pin 4 absorbs radial inclination of the cam groove, uneven groove width, distortion of the fixed cylinder 1 and cam cylinder 2, etc. that occur during plastic molding, as well as dimensional changes due to temperature changes. and 5 are in contact with the cam grooves 2a and 1a.

<Example> FIG. 2 shows an example of a lens barrel equipped with a lens moving device according to the present invention, and shows a sectional view of the upper half thereof.

In the figure, a fixed barrel 1 holds a lens L ₄ at its rear end, and its inner diameter has a cam groove 1a with an inwardly opened inclined surface 1b and a key groove 1 parallel to the optical axis.
c. The cam cylinder 2 is fitted into the inner diameter part of the fixed cylinder 1, and is provided with a cam groove 2a having an inclined surface 2b open to the outside. It fits into the lens without play and can be moved forward and backward in the direction of the optical axis. Furthermore, the cam cylinder 2 holds a lens L ₃ at its rear, and a movable lens frame 3 holding a lens L ₂ at its inner diameter.
is fitted. A guide pin 4 is fitted into a hole 3a provided in the outer circumference of the movable lens frame 3 in the radial direction, and a coil spring 6 is inserted into the hole 4a formed in the guide pin 4 so that the guide pin 5 is coaxially connected. It is embedded in The pins 4 and 5 are the cam groove 2a of the cam cylinder 2 and the cam groove 1a of the fixed cylinder 1, respectively.
The surfaces that are in contact with the cam grooves form sloped surfaces having the same slope angles as the sloped surfaces 2b of the cam grooves 2a and the sloped surfaces 1b of the cam grooves 1a, respectively,
The coil spring 6 causes the pin 4 to move into the cam groove 2.
The pins 5 are simultaneously urged to abut on the inclined surfaces 2b of the cam grooves 1a and the inclined surfaces 1b of the cam grooves 1a, respectively. Therefore, the pins 4 and 5 are located at the intersection of the cam grooves 2a and 1a, and when the cam barrel 2 moves in the optical axis direction, the lens _L2 is moved by displacing the intersection in the optical axis direction.

The operating ring 8 is fitted around the outer periphery of the fixed barrel 1, is coupled to the cam barrel 2 so as to be rotatable and movable integrally in the optical axis direction, and has a key parallel to the optical axis on its inner diameter. It has a groove 8a. The front tube 9 holds the focus lens L ₁ and is helicoid-coupled to the front outer circumference of the cam tube 2, and the key screw 10 implanted on the outer circumference engages with the key groove 8a of the operating ring 8 without play. When the operation ring 8 is rotated, the front cylinder 9 is connected to the cam cylinder 2 in a helicoidal manner.
moves in the optical axis direction, and focusing is performed.

FIG. 3 shows another embodiment of the present invention, showing a sectional view of the main part thereof.

This embodiment differs from the cam groove 1a of the fixed barrel 1 and the cam groove 2 of the cam barrel 2 in the embodiment shown in FIG.
The inclination angles of a are reversed. That is, the fixed cylinder 11 is provided with a cam groove 11a having an inclined surface 11b opening toward the outside, and the cam tube 12 is provided with a cam groove 12a having an inclined surface 12b opening toward the inside. On the other hand, a guide pin 14 as a cam follower is fitted into a hole 13a provided in the radial direction on the outer periphery of the movable lens frame 13 fitted into the inner diameter part of the cam cylinder 12, and a through hole made in the guide pin 14 is inserted. A guide pin 15 as a cam follower is coaxially fitted into 14a, and the pin 15
A coil spring 16 interposed between the C-ring 17 attached to the inner end of the cam cylinder 12 and the pin 14 biases the pins 14 and 15 toward each other. Cam groove 2
a and the cam groove 11a of the fixed cylinder 11, and the surfaces that are in contact with the cam grooves are respectively cam grooves 12a.
and the inclined surface 11b of the cam groove 11a.
A sloped surface having an angle of inclination equivalent to that is formed.

<Effects of the invention> As explained above, the invention enables the cam follower to accurately follow the cam follower without play even if the two intersecting cam grooves are inclined in the radial direction, thereby guaranteeing lens position accuracy. can. In addition,
By adopting the present invention, it becomes possible to mold the cam groove from plastic, and in that case, it becomes possible to provide a low-cost and lightweight lens barrel.

Furthermore, by making the inclination angles of the two intersecting cam grooves opposite to each other in the radial direction as in the present invention, only one spring is required to bring the two cam followers into contact with the cam grooves. Can be done.

In addition to molding the cam groove of the present invention from plastic, it is also very effective to form it into an inclined surface so that the cam follower can actively come into contact with it.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part of a lens barrel equipped with a lens moving device according to the present invention, and FIG. 2 is a cross-sectional view of the upper half of an embodiment of a lens barrel equipped with a lens moving device according to the present invention. , FIG. 3 is a sectional view of a main part of another embodiment of the present invention. 1, 11...Fixed barrel, 1a, 11a...Cam groove, 1b, 11b...Slope, 2, 12...Cam barrel, 2a, 12a...Cam groove, 2b, 12b...
Inclined surface, 3, 13...Moving lens frame, 3a, 13
a... Hole, 4, 14, 5, 15... Guide pin (cam follower), 4a... Hole, 14a... Through hole, 6, 16... Spring, 8... Operation ring, 17...
C ring, L ₁ , L ₂ , L ₃ , L ₄ ...lens.

Claims (1)

[Scope of utility model registration request] A lens in which a cam follower is inserted into the intersection of a cam groove formed in a fixed barrel and a cam groove formed in a cam barrel, and the movable lens is moved in the optical axis direction by moving the cam follower in the optical axis direction. In the lens barrel, both of the cam grooves are formed as inclined surfaces having inclination angles opposite to each other in the radial direction, and the cam follower is formed of two coaxial cam followers that engage with both of the cam grooves, respectively. The surfaces in contact with the cam grooves are formed to have an inclination angle equivalent to the inclination angle of the cam grooves, and a spring is provided to urge the two cam followers to abut on the inclined surfaces of both the cam grooves. A lens barrel featuring: