JPH11160602A - Helicoide screw for extending lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a helicoid screw mechanism which is accurate and constituted so that rotation resistance is reduced without using grease for lubrication or solid lubricant for extending a lens in the focusing mechanism of a projection lens. SOLUTION: The female helicoid screw 10 is formed of a self lubricating material. The male helicoid screw 21 is formed of a metallic material. For self lubricating material, the porous material impregnated with lubricating oil or the material obtained by embedding powder or beads made of a resin material whose lubricity is high is used. The female helicoid screw member 10 is screwed in a fixed frame 30 by a screw 12 whose lead is small and integrated so that it is freely rotated and the movement thereof in an axial direction is restricted. The screw 21 is formed at one part of a movable frame 20 constituted so that it is freely moved in the axial direction and the rotating direction thereof is restricted by a guide pin 24 inside the frame 30.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a helicoid screw for extending a lens in a focusing mechanism of a projection lens.

[0002]

2. Description of the Related Art A conventional helicoid screw for extending a lens is shown in FIG. In the figure, a clearance 3 is provided in a threaded portion of the female helicoid 1 and the male helicoid 2 for a pool of lubricating grease and a wraparound, and a special grease is used there to absorb uneven rotation and play of the lens barrel. Was. Further, when the helicoid screw is rotationally driven by a motor or the like, a fixed lubricant is applied to a threaded portion of the helicoid screw to reduce rotation resistance.

[0003]

When grease is used in such a helicoid screw, rotation resistance inevitably increases and clearance for the grease to go around the contact surface is required. This is problematic in that grease is easily generated and a grease seal or the like is required.

Further, when a fixed lubricant is applied to the helicoid thread portion, there is a variation in the applied thickness, so that it is necessary to provide a clearance, and there is the same problem as described above. Furthermore, when the helicoid screw coated with the solid lubricant is screwed, when the load is increased to a certain extent, there is a problem that the film is broken and the durability cannot be guaranteed.

SUMMARY OF THE INVENTION An object of the present invention is to use a self-lubricating material as a material for a component forming a helicoid screw in a lens feeding helicoid screw in a focusing mechanism of a projection lens, so that lubricating grease or solid lubrication can be achieved. An object of the present invention is to provide a helicoid screw mechanism with high precision and low rotation resistance without using an agent.

[0006]

In order to achieve the above object, the present invention relates to a helicoid screw for feeding out a lens, wherein at least one of the male and female helicoid screws to be screwed together is made of a self-lubricating material. It is characterized by.

[0007] Further, as the self-lubricating material,
It is characterized by using a porous material impregnated with a lubricating oil or a material in which a low friction resin in the form of powder or beads is dispersed and incorporated in advance.

According to the above configuration, since the self-lubricating material is used for the helicoid screw, it is not necessary to increase the rotational resistance due to grease, to secure clearance for grease accumulation or grease wraparound, and to secure the application thickness of the solid lubricant. Become.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged cross-sectional view showing a threaded state of a lens feeding helicoid screw of the present invention, and FIG. 2 is a cross-sectional view of an embodiment of the lens feeding helicoid screw of the present invention. In FIG. 1, a female helicoid screw 1 is made of a self-lubricating material and a male helicoid screw 2
Is made of metal material. Here, as the self-lubricating material, a porous material impregnated with a lubricating oil, a material in which powder or beads of a highly lubricating resin material is dispersed or embedded in advance, or the like is used. Further, as another material, a resin material having high self-lubricating property, for example, Teflon or polyacetal may be used as the material.

As a method for processing a helicoid screw using such a material, ordinary cutting can be performed, and conventional production equipment can be shared. Female helicoid screw 1
The male helicoid screw 2, whose rotation in the rotation direction is restricted, is driven to rotate by the lens extending operation, and advances and retreats along the axial direction of the screw.

Next, in FIG. 2, a female helicoid screw 1
0 is made of a self-lubricating material, and the male helicoid screw 21 is made of a metal material. Female helicoid screw member 10
Is screwed into the fixed sleeve 30 with the screw 12 having a small lead, and is incorporated in a rotatable manner with limited movement in the axial direction.

In the case of this mechanism, the female helicoid screw 1
By reducing the size of 0, it is possible to easily obtain a high-precision engagement of the helicoid screw. In addition, this can reduce the volume occupied by expensive materials, and also has a cost reduction effect. Male helicoid screw 21 is fixed 3
It is formed in a part of the movable body 20 which is freely movable in the axial direction and whose rotation direction is restricted by the guide pin 24 inside the zero.

Further, the movable body 20 is provided on the fixed body 30 so as to limit the backlash in the radial direction of the shaft.
And 23 are provided. Focusing of the fixed lens 30 and the movable lens is performed by moving the movable lens 20 in the axial direction. In this case, the notch 13 provided in a part of the female helicoid screw member 10 is provided. A drive lever 41 for rotating the female helicoid member 10 from the outside is fitted, and the female helicoid member 10 is rotated according to the focusing operation.
The drive lever 41 is integrated with a rotating ring (not shown) formed on the outer periphery, and rotates by operating the rotating ring.

The female helicoid member 10 is slightly moved in the axial direction while being screwed with the small lead screw 31 of the fixed head 30, while the female helicoid screw 11 and the male helicoid screw 21 are screwed together. Is moved in the axial direction.

[0015]

According to the present invention, since no grease or solid lubricant is used, there is no need for a grease pool, clearance around the grease, and clearance for variations caused by application of the solid lubricant, and thus the screw of the helicoid screw is not required. It is possible to reduce the backlash as compared with the conventional art, and it is possible to configure a more accurate lens feeding mechanism.

Further, since no grease is used, the rotation resistance of the helicoid screw can be reduced, and the durability of the material can be increased since the material itself has lubricity.

[Brief description of the drawings]

FIG. 1 is an enlarged cross-sectional view showing a threaded state of a helicoid screw for lens extension according to the present invention.

FIG. 2 is a sectional view showing a configuration of an embodiment of a helicoid screw for feeding out a lens according to the present invention.

FIG. 3 is an enlarged cross-sectional view showing a threaded state of a conventional lens feeding helicoid screw.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Female helicoid screw 2 Male helicoid screw 3 Clearance 10 Female helicoid screw member 11 Female helicoid screw 13 Notch 20 Moving frame 21 Male helicoid screw 22, 23 Straight fitting part 24 Guide pin 30 Fixed frame 41 Drive lever

Claims (2)

[Claims] 1. A lens feeding helicoid screw according to claim 1, wherein at least one of the male and female helicoid screws screwed together is made of a self-lubricating material. 2. A self-lubricating material, wherein a porous material impregnated with a lubricating oil or a material in which a low friction resin in the form of powder or beads is dispersed and incorporated in advance. 2. The helicoid screw for lens feeding according to 1.