JP2000002829A - Lens barrel for camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the deformation of a lens barrel main body caused by temperature change by making a guide member which is provided separately from the lens barrel main body and where a straight advance guide groove is formed in an optical axis direction of material having a thermal expansion coefficient nearly equal to the lens barrel main body. SOLUTION: Three grooves are formed at equal intervals in parallel with an optical axis L on the inner peripheral surface of the lens barrel main body 12. The guide member 16 is attached in the groove by a machine screw 17. A zoom lens 18 is housed and arranged in a state where it is held in a lens frame body 20 in the main body 12. The member 16 is made of the material having the thermal expansion coefficient nearly equal to the main body 12 in order to prevent the deformation of the main body 12 caused by the temperature change. Since the member 16 separate from the main body 12 is produced of the material having the thermal expansion coefficient nearly equal to the main body 12, the deformation of the main body 12 caused by the temperature change is prevented. Thus, a zoom lens 18 is smoothly moved without being influenced by the temperature change.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel of a camera, and more particularly, to a guide groove formed on an inner peripheral surface of a lens barrel body along an optical axis direction, and a movable lens is moved along the guide groove. The present invention relates to a lens barrel of a camera configured as described above.

[0002]

2. Description of the Related Art In general, a zoom lens device of a camera has a guide pin of a zoom lens engaged with a straight guide groove formed on an inner peripheral surface of a lens barrel body, and a cam pin of the zoom lens is engaged with a cam groove of a cam barrel. By engaging and rotating the cam barrel, zooming is performed by moving the zoom lens back and forth in the optical axis direction along the locus of the cam groove.

In such a zoom lens device, there has been proposed a device in which a guide member made of a material different from that of the lens barrel body is provided, and a guide pin of the zoom lens is fitted into a straight guide groove formed in the guide member (see FIG. 1). JP-A-8-262
No. 302).

[0004]

However, in the conventional lens barrel, the lens barrel body is made of aluminum or magnesium which is lightweight and has good workability, and the lens barrel body is provided with corrosion resistance and abrasion resistance. When the guide member made of steel is provided in consideration of the performance, there is a disadvantage that the barrel body is deformed due to a bimetal effect due to a difference in thermal expansion coefficient between aluminum and magnesium and steel, which adversely affects the movement of the zoom lens. .

The present invention has been made in view of such circumstances, and is directed to a lens barrel for guiding the movement of a movable lens by a guide member separate from the lens barrel main body. An object of the present invention is to provide a lens barrel of a camera capable of preventing deformation.

[0006]

In order to achieve the above object, the present invention provides a lens barrel of a camera having rectilinear guide means for guiding a movable lens so as to be able to move back and forth in the optical axis direction. A guide member provided separately in the lens barrel body and having a straight guide groove formed in the optical axis direction, and a guide pin provided in the movable lens and fitted into the straight guide groove of the straight guide member, The guide member is made of a material having a thermal expansion coefficient substantially equal to that of the lens barrel body.

According to the present invention, since the guide member separate from the lens barrel main body is made of a material having a thermal expansion coefficient substantially equal to that of the lens barrel main body, deformation of the lens barrel main body due to a temperature change can be prevented. it can. Accordingly, in the present invention, the moving lens moves smoothly without being affected by the temperature change.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a lens barrel of a camera according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a cutaway perspective view showing a main part of a lens barrel 10 of a camera according to an embodiment of the present invention, and FIG. 2 is a sectional view of a lens barrel main body 12 of the lens barrel 10.

In the lens barrel body 12 shown in FIG. 2, three grooves 14, 14, 14 are formed on the inner peripheral surface at equal intervals and parallel to the optical axis L. These grooves 14 have guide members 1 to be described later.
6 are respectively attached by screws (see FIG. 1) 17. A zoom lens 18 is provided in the lens barrel body 12.
Are stored and arranged while being held by the lens frame 20. On the outer peripheral surface of the lens frame 20, a pin group including a plurality of guide pins 22, 22, 22 is provided so as to protrude at equal intervals, and these guide pins 22 are linearly formed on the guide member 16. It is slidably fitted in the guide groove 24. Accordingly, the zoom lens 18 can move back and forth along the straight guide groove 24, that is, in the optical axis L direction.

Further, on the outer peripheral portion of the lens frame 20,
A cam pin 26 protrudes. This cam pin 26
It extends to a cam cylinder storage case 28 connected to the lens barrel main body 12, and is engaged with a cam groove 32 of a cam cylinder 30 stored in the storage case 28. Both ends of the cam cylinder 30 are rotatably supported by the storage case 28, and an output shaft of a rotary motor (not shown) is connected to one of the two ends via a speed reduction mechanism. Therefore, when the rotation motor is driven to rotate the cam barrel 30, its power is transmitted to the lens frame 20 via the cam pins 26. Then, the power causes the zoom lens 18 to move back and forth in the optical axis L direction while being guided by the linear guide groove 24.

Next, the guide member 16 will be described. The guide member 16 is used to move the lens barrel body 1 due to a temperature change.
In order to prevent deformation of the lens body 2, the lens barrel body 12 is made of a material having substantially the same thermal expansion coefficient. Here, the materials of the lens barrel main body 12 and the guide member 16 will be exemplified. [Example 1] Lens body: AC4C-T6 (aluminum casting), coefficient of thermal expansion: 23 to 24 (10 ^-6 / ° C) Guide member: BERIC (zinc alloy), coefficient of thermal expansion: 2
4 (10 ^-6 / ° C) [Example 2] Lens barrel body: MC8 (magnesium casting), coefficient of thermal expansion ...
26 to 27 (10 ⁻⁶ / ° C.) Guide member: ZDC1 (zinc alloy), thermal expansion coefficient: 27
(10 ^-6 / ° C) [Example 3] Lens barrel body: MC8 (magnesium casting), thermal expansion coefficient ...
26 to 27 (10 ^-6 / ° C) Guide member: ZDC2 (zinc alloy), thermal expansion coefficient: 27
(10 ^-6 / ° C) [Example 4] Lens barrel body: MC2 (magnesium casting), thermal expansion coefficient ...
27 (10 ⁻⁶ / ° C.) Guide member: ZDC1 or ZDC2 (zinc alloy), coefficient of thermal expansion: 27 (10 ⁻⁶ / ° C.) [Example 5] Lens barrel body: MC6 (magnesium casting), coefficient of thermal expansion:
27.3 (10 ⁻⁶ / ° C.) Guide member: ZDC1 or ZDC2 (zinc alloy), coefficient of thermal expansion: 27 (10 ⁻⁶ / ° C.) In the present embodiment, the above five examples have been described, but only in this example. It is not something that can be done. That is, a material having a thermal expansion coefficient substantially equal to that of the lens barrel body 12 may be selected as the guide member 16.

When the BERIC shown in Example 1 is applied as the guide member 16, this material is hard and has high wear resistance, so that the service life can be extended. That is, since the guide member 16 is a consumable item, it is preferable to select a material that is hard and has high wear resistance from the viewpoint of extending the service life. As described above, in the present embodiment, since the guide member 16 is made of a material having substantially the same thermal expansion coefficient as the lens barrel body 12, deformation of the lens barrel body 12 due to temperature change can be prevented, and the zoom lens 18 can be smoothly moved. Can be moved.

In this embodiment, the zoom lens 1
Although the eight lens barrel 10 has been described, the present invention is not limited to this, and the present invention can be applied to a lens barrel of a focus lens. Further, in the present embodiment, the description has been given of the embodiment in which the guide member 16 is provided on the lens barrel main body 12 and the guide pin 22 is provided on the lens frame 20.
The present invention is not limited to this, and the present invention can be applied to a lens barrel in which the guide pins 22 are provided on the barrel main body 12 and the guide members 16 are provided on the lens frame 20.

[0014]

As described above, according to the lens barrel of the camera according to the present invention, the guide member separate from the lens barrel main body is made of a material having a thermal expansion coefficient substantially equal to that of the lens barrel main body. Further, deformation of the lens barrel main body due to a temperature change can be prevented. Thereby, according to the lens barrel of the camera of the present invention, the movable lens moves smoothly without being affected by the temperature change.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a lens barrel of a camera according to the present invention.

FIG. 2 is a sectional view of the lens barrel shown in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Lens barrel 12 ... Lens barrel body 16 ... Guide member 18 ... Zoom lens 22 ... Guide pin 24 ... Straight guide groove 26 ... Cam pin 30 ... Cam cylinder 32 ... Cam groove

Claims (1)

[Claims] 1. A lens barrel for a camera having a linear guide means for guiding a movable lens so as to be able to move back and forth in the optical axis direction, wherein said linear guide means is provided separately on a lens barrel body and has a linear guide groove. A guide member formed in the optical axis direction and a guide pin provided on the moving lens and fitted into a rectilinear guide groove of the rectilinear guide member, wherein the guide member has a material having a thermal expansion coefficient substantially equal to that of the lens barrel body. A lens barrel for a camera, characterized by being made of