JPH0545620U - Lens barrel - Google Patents

Abstract

(57) [Summary] [Purpose] Without adding parts that increase costs,
Prevents damage to the teeth of the drive gear. [Structure] Fixed lens barrel 2 and gear 5 axially supported by the fixed lens barrel
a, a drive ring 3 arranged outside or inside the fixed barrel and having a gear that meshes with a gear, a printed circuit board 9 provided on one of the opposing faces of the drive ring or the fixed barrel, and the fixed barrel. Or a brush 8 having one end fixed to the drive ring and the other end slidingly contacting the printed circuit board, the meshing portion D between the gear of the fixed lens barrel and the gear of the drive ring, and the sliding contact range between the brush and the printed circuit board. B and B are arranged at positions substantially symmetrical with respect to the optical axis.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an encoder having a brush and a printed circuit board (hereinafter, simply referred to as a printed circuit board) having an electrode pattern as components, and a lens barrel having a plurality of drive gears, and particularly, the arrangement of the encoder and the drive gear is improved. It is related to the lens barrel.

[0002]

[Prior Art]

 Conventionally, as this type of lens barrel, there is known one having an encoder having a brush and a printed circuit board as components, and a plurality of drive gears, in which focusing is performed by a driving force transmitted from a camera body. There is. FIG. 3 is a vertical half sectional view showing an example of a conventional lens barrel. The fixed barrel 2 supports the focusing ring 3 rotatably about the optical axis by the inner peripheral surfaces 2b, 2c, 2d. Further, at the rear end portion of the fixed lens barrel 2, there is a coupling portion (mount) 2a with a camera body (not shown).

An internal gear 3 a is formed at the rear end of the focusing ring 3, and the internal gear 3 a is a pinion part of a coupling shaft 5 that is axially supported by bearings 2 e and 2 f of the fixed lens barrel 2. It meshes with 5a. The coupling shaft 5 transmits a driving force from a camera body (not shown), and has a concave coupling portion 5b at its rear end.

The lens frame 7 supporting the lens 6 is provided with a female helicoid screw 7 a, and the female helicoid screw 7 a meshes with the male helicoid screw 2 g provided on the fixed barrel 2. The lens frame 7 is provided with a key protrusion 7b, and the key protrusion 7b is engaged with the key groove 3b on the inner peripheral portion of the focusing ring 3.

Next, the operation of the lens barrel having the above configuration will be described. When the lens barrel 1 is attached to the camera body (not shown) via the coupling portion 2a, the convex portion of the drive shaft on the camera body side engages with the coupling portion 5b of the coupling shaft 5 to transmit the driving force. It will be possible. When the drive source of the camera body is driven, the coupling shaft 5 rotates, and this rotation is transmitted to the pinion portion 5a of the coupling shaft 5 and then to the internal gear 3a of the focusing ring 3 to rotate the focusing ring 3. ..

As described above, the key protrusion 7b of the lens frame 7 is engaged with the key groove 3b of the focusing ring 3, and the female helicoid screw 7a is engaged with the male helicoid screw 2g of the fixed lens barrel 2, so that focusing is performed. The rotation of the ring 3 causes the lens frame 7 to perform a spiral movement, that is, the lens frame 7 moves back and forth while rotating with respect to the fixed lens barrel 2 for focusing.

Here, the focusing ring 3 is provided with a rotation limiting protrusion 3c, and the rotation limiting protrusion 3c collides with the notch 2h of the fixed barrel 2 when the focusing ring 3 rotates by a predetermined angle. It is like this. Therefore, the focusing ring 3 can rotate only within a predetermined angle range. Although not shown, the lens barrel 1 also incorporates a distance encoder that emits an electric signal corresponding to the photographing distance. This distance encoder includes a brush that moves integrally with the focusing ring 3 in a circumferential direction and a print substrate provided on the fixed barrel 2 so as to be in sliding contact with the brush in a specific rotation range of the focusing ring 3. It is a component.

[0008]

[Problems to be solved by the device]

 However, in the above-described conventional lens barrel, when the internal gear 3a of the focusing ring 3 and the pinion 5a of the coupling shaft 5 are normally meshed during driving, the meshed state shown by the solid line in FIG. As indicated by the chain double-dashed line, the internal gear 3a may escape toward the outer diameter side, resulting in an abnormal state in which the meshing is shallow.

This abnormal meshing is mainly due to the gap between the inner peripheral surface 2d of the fixed lens barrel 2 and the outer peripheral surface 3d of the focusing ring 3 which is in sliding contact therewith. However, when considering the smooth operation of the focusing ring 3, an appropriate gap is necessary, and in particular, the fixed lens barrel 2 and the focusing ring 3 are made of different materials having different linear expansion coefficients (for example, If it is made of a combination of aluminum and plastic), considering the difference in the coefficient of linear expansion between the two, a considerable gap is required so that the focusing ring 3 can rotate smoothly when used at high or low temperatures. Need to be provided.

As described above, when the driving force from the camera body is transmitted in the shallow meshing state, stress concentrates on the tooth tips of the internal gear 3a and the pinion 5a. In particular, when the limiting projection 3c of the focusing ring 3 and the notch 2h of the fixed lens barrel come into contact with each other, a large stress is generated at the tooth tip due to the impact, which may damage the tooth. ..

The present invention has been made in view of the problems of the conventional lens barrel, and damages of gear teeth such as a fixed barrel and a focusing ring can be performed without adding cost-up parts. It is an object of the present invention to provide a lens barrel which is prevented.

[0012]

[Means for Solving the Problems]

 In order to solve the above problems, a lens barrel according to the present invention comprises a fixed barrel (2), a gear (5a) axially supported by the fixed barrel, and an outer or inner side of the fixed barrel. A drive ring (3) having a gear that meshes with the gear, a printed circuit board (9) provided on one of the opposing surfaces of the drive ring or the fixed cylinder, and the fixed cylinder or A lens barrel having a brush (8) having one end fixed to the drive ring and the other end slidably contacting the printed circuit board, wherein a gear portion of the fixed lens barrel and a gear of the drive ring are meshed with each other. (D) and the sliding contact range (B) between the brush and the printed circuit board are arranged at positions substantially symmetrical with respect to the optical axis.

[0013]

[Action]

 According to the present invention, for example, the brush 8 fixed to the inner peripheral portion of the drive ring 3 is in sliding contact with the pattern 8 of the printed circuit board 9 provided on the fixed barrel 2 with an appropriate contact pressure. Here, since the pinion 5a and the meshing portion D of the internal gear 3a are substantially symmetrical with the sliding contact range B between the brush 8 and the printed circuit board 9 as the optical axis, the contact pressure causes the drive ring 3 to move to the pinion. 5a and the internal gear 3a act in the direction of deepening the meshing. Therefore, even if there is a gap between the drive ring 3 and the fixed lens barrel 2, the meshing does not become shallow, and damage to the gear teeth can be prevented. Moreover, in the present invention, the installation position of the encoder, which is conventionally provided by a brush or the like, is changed, and it is not necessary to add new parts.

[0014]

【Example】

 Hereinafter, the present invention will be described in detail with reference to the drawings and the like. FIG. 1 is a horizontal cross-sectional view (cross-sectional view taken along the line CC in FIG. 2) showing an embodiment of a lens barrel according to the present invention, and FIG. 2 is a vertical cross-sectional view showing the lens barrel according to this embodiment. .. The same parts as those of the conventional lens barrel shown in FIG. 3 are designated by the same reference numerals. The focusing operation of the lens barrel 1 is the same as that of the conventional lens barrel shown in FIG. Therefore, here, the points different from the conventional lens barrel shown in FIG. 3 will be mainly described.

In FIGS. 1 and 2, the brush 8 is fixedly attached to the inner diameter portion of the rear end of the focusing ring 3 by a screw 10. On the other hand, a printed circuit board 9 is installed on the fixed barrel 2, and the tip of the brush 8 is in sliding contact with it. Here, the sliding contact area B between the brush 8 and the printed circuit board 9 due to the rotation of the focusing ring 3 and the meshing portion D between the pinion 5a and the internal gear 3a are arranged at substantially symmetrical positions in a plane perpendicular to the optical axis 4. Has been done.

Therefore, due to the contact pressure of the brush 8 to the printed circuit board 9, the focusing ring 3 always receives a force in the direction in which the engagement between the pinion 5a and the internal gear 3a becomes deep, and rotates while being displaced in this direction. ..

Therefore, even if there is a gap between the fixed lens barrel 2 and the focusing ring 3, especially between the surfaces 2d and 3d, the pinion 5a and the internal gear 3a mesh with each other when the focusing ring 3 rotates. Does not become shallow, stress concentration on the tips of gear teeth is prevented, and damage is prevented.

In the above embodiment, the encoder including the brush 8 or the like determines the shooting distance, but the present invention is not limited to this, and a brush for other purposes may be used. Good. Further, the present invention can be applied even if there are a plurality of brushes 8 in the circumferential direction. Further, it can be applied to a lens barrel in which the fixed barrel 2 is arranged outside the focusing ring 3. It is also applicable to the case where the brush 8 is provided on the fixed barrel 2 side and the printed circuit board 9 is provided inside the focusing ring 3. Furthermore, although the case where focusing driving is performed has been described as an example, it can be adopted for zooming and other driving mechanisms.

[0019]

[Effect of the device]

 As described above, according to the lens barrel of the present invention, the sliding contact area between the brush and the printed circuit board is arranged substantially symmetrically with respect to the optical axis, and the meshing portion of the gear for transmitting the driving force is arranged. Since the engagement of the gears works in the direction of deepening, damage to the teeth of the gear can be prevented without adding costly parts.

[Brief description of drawings]

FIG. 1 is a transverse sectional view (a sectional view taken along the line CC in FIG. 2) showing an embodiment of a lens barrel according to the present invention.

FIG. 2 is a vertical sectional view showing an embodiment of a lens barrel according to the present invention.

FIG. 3 is a vertical half sectional view showing a conventional lens barrel.

FIG. 4 is a partially enlarged view of a meshing state of an internal gear and a pinion as seen from a direction A in FIG.

[Explanation of symbols]

 1 Lens barrel 2 Fixed barrel 3 Focusing ring 3a Internal gear 4 Optical axis 5 Coupling axis 5a Pinion 8 Brush 9 Printed circuit board

Claims (1)

[Scope of utility model registration request] 1. A fixed lens barrel, a gear wheel axially supported by the fixed lens barrel, a drive ring having a gear wheel arranged outside or inside the fixed lens barrel and meshing with the gear wheel, and the drive ring. Alternatively, a lens barrel having a printed circuit board provided on one of the facing surfaces of the fixed barrel and a brush having one end fixed to the fixed barrel or the drive ring and the other end slidingly contacting the printed circuit board. The meshing portion between the gear of the fixed barrel and the gear of the drive ring, and the sliding contact range between the brush and the printed circuit board,
A lens barrel, which is arranged in a position substantially symmetrical with respect to an optical axis.