JPS63148213A - Lens straight extending device - Google Patents

Abstract

PURPOSE:To preclude deviation due to a change in the attitude of a body and slight vibrations by pressing one flank of a key and one wall surface of a key groove which engage each other for the straight guidance of a lens against each other by a pressing means and generating a large frictional force between the both. CONSTITUTION:The key 11 and key groove 10 are provided so that when a 1st helicoid member 3 rotates, a 2nd helicoid member 8 moves straight along an optical axis without rotating. The pressing means 12 presses the key and key groove so that one flank of the key 11 and one groove wall 10c of the key groove 10 are pressed to contact each other. Consequently, the 1st helicoid member 3 is moved finely according to the lead of a helicoid screw by rotation and when the 1st helicoid member 3 stops rotating, it is fixed at the position to preclude deviation against a change in the attitude of the body and slight vibrations because of the large frictional force.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a lens feeding device for an optical device, particularly a lens feeding device that moves a lens in a straight line by rotating a helicoid screw provided in a lens barrel. Regarding improvements.

(Prior art) In optical devices such as cameras, a female helicoid screw is provided on the inner periphery of a rotatable annular member, and a lens holding member having a male helicoid screw that engages with the female helicoid screw is connected to a key and a keyway. A lens feeding device configured to move the lens straight in the optical axis direction is generally used. In particular, the rotatable annular member is supported by the body via another helicoid screw, and the lens is thick for small rotation angles (the lens advancing device that moves the lens straight is a double helicoid system, which is often used in photographic lens barrels, etc.). It is being

This type of helicoid is designed so that the lens can be moved largely in the optical axis direction with a relatively small amount of rotation of the annular member.
It is formed on Mt. Tajo Neshiyama. Therefore, even if there is a slight loosening between the male thread and the female thread, it will appear as a large sludge in the optical axis direction. Similar to the backlash between the key and the keyway, this helicoid screw sludge can cause the lens holding member to shift due to changes in the posture of the device or slight vibrations, even if the lens is positioned in the correct position. The sludge or backlash causes the lens to shift to one side and cause the lens to be misaligned.

Therefore, conventionally, in order to prevent the lens position from being misaligned,
A method of precisely fitting the key and the keyway, and the male and female threads of a helicoid screw by matching the actual items, changing the shape of the threads, or adding elasticity to a part of the threads. A method of removing sludge was used.

(Problems to be Solved by the Invention) However, all of the above-mentioned lens misalignment prevention methods mainly prevent lens misalignment by removing the sludge of the helicoid screw, and the former method is based on alignment of the actual product. This method not only causes variations in fitting accuracy, but also has the drawbacks of no compatibility and high cost. In addition, the latter method of deforming the thread or using an elastic body for a part of the thread not only complicates the structure of the thread, but also still poses the problem of play in the fit between the key and the keyway. Not resolved.

The present invention solves the problems of the conventional device described above, and even if there is some backlash or sludge between the helicoid screw or the key and the keyway, the lens can move straight with high precision and the posture of the body can be adjusted. It is an object of the present invention to provide a lens linearly advancing device that does not go out of order even when subjected to changes or some vibrations.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the present invention includes a first helicoid member rotatably supported with respect to a fixed portion of a body, and a helicoid attached to the first helicoid member. In a lens feeding device having a second helicoid member that is screwed together via a screw, a key groove is provided in either one of the fixing portion of the body and the second helicoid member, and a key that engages with the key groove is provided in the other; A means to solve the problem is to provide a pressurizing means that presses one side of the key and one side wall of the keyway into contact with each other, and to generate a frictional braking force on the contact surface. It is.

(Function) The key (11) and keyway (10) are provided so that when the first helicoid member 3 rotates, the second helicoid member (8) moves straight along the optical axis without rotating. . The pressing means (12) applies pressure so that one side surface of the key (11) comes into pressure contact with one groove wall (10c) of the key groove (10). As a result, even if there is a gap between the key (11) and the keyway (10), the keyway (10)
) and one side of the key (11) are always in contact with each other, and the second helicoid member (8) does not play with respect to the fixed portion (1a) of the body (1) in the rotational direction about the optical axis. Therefore, the second helicoid member (8) has a helicoid neck 9
It is paid out accurately according to the lead in a). moreover,
The key (11) and key groove (
10) Frictional braking force is generated on the pressing contact surface with. As a result, the rotation of the first helicoid member 3 causes the first helicoid member to move precisely according to the lead of the helicoid wire, and when the rotation of the first helicoid member 3 stops, it is fixed at that position, resulting in a large static friction. This ensures that the position does not shift even when the body posture changes or there is some vibration.

(Example) Next, an example of the present invention will be described in detail based on the accompanying drawings.

1 is a sectional view of a lens barrel showing an embodiment of the present invention, and FIG. 2 is a sectional view taken along line nn in FIG.

In FIG. 1, an annular member 3 is screwed and supported on a fixed portion 1a of a camera body 1 via a screw 2. As shown in FIG.

A gear 4 is provided on the outer periphery of this annular member 3, and a drive gear 5 that meshes with this gear 4 is rotationally driven by a motor 6. The lens holding tube 8 that holds the shadow loss lens 7 has a male helicoid screw 9b that is screwed into a female helicoid screw 9a formed on the inner periphery of the annular member 3.
As shown in FIG. 2, two keyways 10 are formed on the inner periphery of the cylindrical portion on the right side in the figure, sandwiched between two radially projecting protrusions 10a and 10b.

The key 11 that engages with the key groove 10 extends long in the optical axis direction as shown in FIG.
It is fixedly installed. Further, a leaf spring 12 is fixed to the bottom surface 8a of the cylindrical portion of the lens holding tube 8 with a machine screw 13, and the free end 12a of the leaf spring 12 engages with one side surface 11a of the key II. This is pressurized. Note that the protrusion 10a is formed on the inner surface of the cylindrical portion of the lens holding tube 8 to be elongated in the optical axis direction, and the protrusion 10b is formed on the end of the cylindrical portion to protrude as shown in FIG. The key 11, the keyway 10, and the leaf spring 12 are all provided at substantially symmetrical positions with respect to the optical axis, as shown in FIG.

Since the embodiment shown in FIG. 1 is constructed as described above,
When the drive gear 5 is rotated by the motor 6, the annular member 3 is rotated via the gear 4. When this annular member 3 rotates, the annular member 3 rotates according to the pitch of the screw 2, and as it moves slightly in the optical axis direction, the lens holding cylinder 8 also tries to rotate, but this rotation is controlled by the key 11. thwarted. Since the free end 12a of the leaf spring 12 is in pressure contact with one end surface of the key 11, the key 11 is always in contact with one groove wall 10C of the key groove 10, and this groove wall 1
0c slides against the other end surface of the key 11, so that the lens holding cylinder 8 moves straight along the optical axis without rotating. Therefore, no looseness occurs in the engagement between the key 11 and the keyway 10.

However, in this case, since a frictional force due to the biasing force of the slope spring 12 acts between the key 11 and the key groove wall 10c on the lens holding tube 8, the helicoid screw 9b is The rear surface of the thread is always in contact with the front surface of the thread of the helicoid screw 9a of the annular member 3 with an appropriate contact pressure, and the rear surface of the thread of the female thread 9a and the front surface of the thread of the male thread 9b are in contact with each other. A gap corresponding to the sludge of the screw is created.

When the photographing lens 7 is extended to a predetermined position in the direction of the arrow in FIG. will be stopped. This annular member 3
By stopping the rotation, the lens holding cylinder 8 immediately stops moving straight while leaving a certain gap between the rear side surface of the thread of the female thread 9a and the front side surface of the thread of the male thread 9b.

In this case, the lens holding tube 8 is fixed to the fixed portions 1a and T of the camera body 1 by the static friction force generated between the side wall 10C of the key groove 10 and the side surface of the key 11 due to the biasing force of the leaf spring 12.
h They are integrally connected, and due to their frictional connection, their position will not change due to their own weight or the force of some vibration. Therefore, the photographing lens 7, which has been positioned by the rotation of the annular member 3, will not be out of position unless the annular member 3 rotates again.

Note that the spring member that prevents play between the key 11 and the key groove 10 and suppresses the movement of the lens holding tube 8 in the optical axis direction, and the key 11 and the key groove may be used as a pair, but they are symmetrical with respect to the optical axis. By arranging the lens holding tube 8, only one of the outer peripheries of the lens holding tube 8 is prevented from moving in the optical axis direction, thereby preventing the lens holding tube 8 from tilting and moving, or from tilting to one side due to vibration. can. Further, although the temporary spring 12 is used in the embodiment shown in FIG. 1 as a means for suppressing the movement of the lens holding cylinder 8, an elastic body such as synthetic rubber having wear resistance may also be used. .

Further, in the embodiment shown in FIG. 1, the screw 2 that rotatably holds the annular member 3 is a helicoid screw, and may be configured as a double helicoid screw.

〔Effect of the invention〕

As described above, according to the present invention, the key and the keyway that engage with each other in order to guide the lens in a straight line are moved by the plate spring (pressing means).
The structure is extremely simple because one side of the key and one wall of the key groove are brought into pressure contact and a large frictional force is generated between them. Even if the helicoid screw has a slug, the second helicoid member) will not lose its position due to changes in body posture or vibration, and
Since there is no play between the key and the keyway, the annular member (
The rotation of the first helicoid member) and the linear movement of the lens holding cylinder (second helicoid member) can be made to correspond accurately.

Furthermore, when the annular member (first helicoid member) is rotatably supported by a helicoid screw to form a double helicoid screw, only one set of keys, key grooves, and leaf springs (
The pressure means) is extremely effective in preventing misalignment of the lens holding cylinder against the double axial thrust.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal cross-sectional view showing an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line -■ in FIG. (Explanation of symbols of main parts) 1... Body, 1a... Fixed part 3... Annular member (first helicoid member) 8... Lens holding tube (second helicoid member) 10... Key Groove, 1
1... Key 12... Leaf spring (pressurizing means)

Claims (3)

[Claims] (1) A lens feeding device having a first helicoid member that is rotatably supported with respect to a fixed portion of the body, and a second helicoid member that is threadedly engaged with the first helicoid member via a helicoid screw. A key groove is provided on one of the fixed portion and the second helicoid member, and a key that engages with the key groove is provided on the other, and one side surface of the key and one wall surface of the key groove are pressed into contact with each other. What is claimed is: 1. A lens linear advancing device, characterized in that it is provided with a pressurizing means that acts to act so as to cause a frictional braking force to be generated on a contact surface between the key and the keyway. (2) The key (11) is a fixed part (1a) of the body.
The pressurizing means is a leaf spring member (12) and is provided on the second helicoid member (8) so as to press the other side surface of the key (11). 2. The lens linear advancing device according to claim 1, wherein the lens linearly advancing device is fixedly installed in the vicinity of the keyway (10). (3) The keyway (10), the key (11), and the pressurizing means (12) are each provided at two locations symmetrical with respect to the optical axis of the lens. The lens linear advancing device according to item 1 or 2.