JP2000047082A - Lens barrel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens barrel by which protruding amount from the front surface of a camera can be reduced, and assembling operation can be facilitated, etc. SOLUTION: A polygonal base plate 91 is fitted and inserted in the annular space 87 of a rear part protecting ring 81 in a state where the plate 91 is along the inside peripheral surface of an inside barrel part 85. As to the plate 91; the stay part 93 is screwed and fixed to the rear surface of a fixed barrel 3, on the other hand, a polygonal flexible printed circuit board 99 on the outside peripheral surface of which electric parts 95 to 97 are loaded is stuck. In the case of the assembling of the lens barrel, the ring 81 is fitted and fixed to a fixed mount 1 after the board 99 is stuck to the plate 91 fixed to the barrel 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lens barrel mounted on a camera, and more particularly, to a technique for reducing the amount of protrusion from the front of the camera and facilitating assembly work.

[0002]

2. Description of the Related Art A camera is equipped with various types of lens barrels including a single focus lens and a zoom lens. The lens barrel has a plurality of lens groups each including one or a plurality of optical lenses, and focusing and zooming are performed by appropriately changing the distance between the lens groups. Therefore, the lens barrel has a plurality of lens group holding frames used for holding each lens group and a plurality of cam rings for driving the lens group holding frames, and each lens ring is rotated by rotating each cam ring. A structure is adopted in which the group holding frame moves back and forth along the optical axis. For example, the inner focus type zoom lens barrel has a focus drive ring and a zoom cam ring, and the focus lens ring holding frame moves forward and backward by the rotation of the focus drive ring, and the focus lens group is held by the rotation of the zoom cam ring. In some cases, both the frame and the zoom lens group holding frame move back and forth.

On the other hand, in recent years, even in relatively low-priced cameras, in addition to a manual focus mode in which a photographer performs focusing, an autofocus mode in which focusing is performed by the camera itself has become mainstream. In this type of camera, a microcomputer, a CCD sensor, an electric motor, and the like are incorporated in the camera body, and when the distance to the subject is detected, the electric motor moves forward through the focus lens group holding frame in the lens barrel. Or, it is structured to be driven backward. Therefore, in order to detect the rotational position of the focus drive ring and transmit it to the microcomputer on the camera side, electric components such as a rotary encoder and a signal processing chip are mounted on the flexible printed circuit board in the lens barrel. ing.

[0004]

In a conventional lens barrel, a flexible printed circuit board is often attached to the inner periphery of a fixed barrel or the like, which leads to an increase in the length and weight of the lens barrel. There was a problem. For example, when the width of the flexible printed circuit board is large, a cylindrical surface having a width equal to or greater than the width must be secured on the inner periphery of the fixed cylinder, and the entire length of the fixed cylinder is required for supporting the lens group holding frame and cam ring. It is larger than the value. Further, when a flexible printed circuit board on which electric components are mounted is provided between the fixed cylinder and the lens group holding frame, it is necessary to secure a sufficient gap between the fixed cylinder and the lens group holding frame. Occurs, and the outer diameter of the fixed cylinder becomes unnecessarily large. Furthermore, due to the fact that a rotary encoder is mounted on a flexible printed circuit board, it is necessary to pay close attention to its attachment, which has been a factor that hinders an increase in the number of work steps and a response to mass production. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a lens barrel in which the amount of protrusion from the front of the camera is reduced, assembly work is facilitated, and the like.

[0005]

In order to solve the above problem, according to the first aspect of the present invention, there is provided a lens barrel having a rear protective ring for protecting an optical lens protruding from a rear end of a lens mount, It is proposed that an annular space opened forward is formed in the rear protective ring and at least a part of the flexible printed circuit board is accommodated in the annular space. According to the present invention, the portion of the flexible printed circuit board that is disposed on the portion of the lens barrel that protrudes from the camera is reduced, and the length of the fixed cylinder due to the flexible printed circuit board is suppressed.

According to a second aspect of the present invention, there is provided the lens barrel according to the first aspect, wherein the flexible printed circuit board has an electric component mounted on a part thereof.
According to the present invention, it is not necessary to secure a space for electric components between the fixed cylinder and the lens group holding frame and the like, and the diameter and weight of the fixed cylinder are prevented from increasing.

According to a third aspect of the present invention, there is provided the lens barrel according to the first or second aspect, wherein the flexible printed circuit board is fixed to an inner peripheral side of the annular space. According to the present invention, the flexible printed circuit board can be easily fixed to the rear protection ring.

According to a fourth aspect of the present invention, in the lens barrel according to the third aspect, the flexible printed circuit board comprises:
It is proposed that the annular space is fixed to the inner peripheral side of the annular space via a metal base plate. According to the present invention, the flexible printed circuit board is securely fixed, and the assembling workability is further improved.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a zoom lens barrel according to an embodiment of the present invention, and FIG. 2 is a half longitudinal sectional view of a portion different from FIG. 1 and 2, a member denoted by reference numeral 1 is a fixed mount attached to a camera (not shown), and a plurality of bayonet lugs 2 are formed on an outer peripheral surface thereof. A fixed tube 3 having a cylindrical shape is fixed to the front end of the fixed mount 1 by a method such as screw fastening. A zoom ring 5 is rotatably supported at the front end of the fixed barrel 3. A guide groove 7 formed on a part of the outer circumferential surface of the fixed barrel 3 and an inner circumferential face of the zoom ring 5 are formed. The zoom ring 5 can rotate within a predetermined angle range by engaging the pin 9 thus set. In the figure, reference numeral 11 denotes a rubber ring for preventing slippage when the zoom ring 5 is operated, and is fitted on the outer peripheral surface of the zoom ring 5. Reference numeral L denotes an optical axis that is the center of travel of light from a subject, and a rotating component such as the zoom ring 5 rotates around the optical axis L.

A zoom cam barrel 21 having a cylindrical shape is disposed inside the zoom ring 5, and the zoom ring 5 and the zoom cam barrel 21 are integrally rotated by a photographer's operation. A plurality (three in this embodiment) of cam projections 31 are provided on the outer peripheral surface of the zoom cam cylinder 21. Zoom ring 5
A cylindrical rectilinear ring 33 is provided between the zoom cam barrel 21 and the cam projection 31 of the zoom cam barrel 21.
Front and rear cam followers 3 protruding from the inner peripheral surface of the straight running ring 33
5, 37 are engaged. Thereby, the zoom cam barrel 2
When the zoom ring 1 (that is, the zoom ring 5) rotates, the straight ring 33
Move back and forth along the optical axis L. In addition, straight ring 3
A plurality of (two in the present embodiment) guide grooves 39 are formed on the rear outer peripheral surface of the rear part 3 in parallel with the optical axis L, and these guide grooves 39 are directed inward from the front end of the fixed cylinder 3. The engagement of the projecting restraining projections 41 restrains the rotation of the rectilinear ring 33.

A focus ring 53 holding a first lens group 51 composed of two lenses is disposed in front of the rectilinear ring 33, and its cylindrical portion 55 is fitted on the rectilinear ring 33. A male helicoid screw 57 is formed on the outer peripheral surface of the rectilinear ring 33, while a female helicoid screw 59 is formed on the inner circumference of the cylindrical portion 55 of the focus ring 53, and these male helicoid screw 57 and female helicoid screw 59 are formed. And are screwed together. Therefore, when the focus ring 53 is rotated by the photographer or the like, the focus ring 53 advances and retreats along the optical axis L with respect to the rectilinear ring 33 according to the amount of rotation.

On the other hand, the zoom cam cylinder 21 has a plurality of spiral cam grooves 61 on its inner peripheral surface (in this embodiment, three cam grooves 61).
Book) carved. A lens holder 65 that holds a second lens group 63 composed of four lenses is fitted inside the zoom cam barrel 21, and the cam groove 6 of the zoom cam barrel 21 is
1 is engaged with an interlocking projection 67 protruding from the outer peripheral surface of the lens holder 65. A not-shown rectilinear interlocking key fixed to the fixed barrel 3 is engaged with the lens holder 65. When the zoom cam barrel 21 (that is, the zoom ring 5) rotates, the lens holder 65 Since the rotation is restricted, it advances and retreats along the optical axis L.

A drive ring 71 is rotatably held inside the fixed cylinder 3 immediately before the fixed mount 1. As shown in FIG. 2, the front end face of the drive ring 71 has
Bifurcated connection keys 73 extend forward at intervals of 80 °, and a connection key 75 extending rearward from the rear end face of the focus ring 53 is engaged with these connection keys 73.
That is, in the present embodiment, both the connection keys 73 and 75 form a connection portion, whereby the focus ring 53 and the drive ring 71 rotate integrally, but both can move relatively in the front-back direction. Has become. In FIG. 1, reference numeral 77 denotes a drive ring 71.
Are engaged with the lens-side coupling gear 106 shown in FIG.
a and the drive coupling 104 on the camera side. The camera side coupling 104 is driven by a motor 105 in the body. Reference numeral 3a denotes a relief provided on the fixed cylinder for the coupling gear 106.

In this embodiment, a rear protective ring 8 is provided at the rear end of the fixed mount 1 to protect the second lens group 63.
1 is protruded. The rear protective ring 81 is a synthetic resin injection molded product (or an aluminum alloy die-cast molded product), and is formed in a double cylindrical shape including an outer cylindrical portion 83 and an inner cylindrical portion 85. An air gap with the inner cylinder portion 85 forms an annular space 87 opened forward.
Note that the rear protection ring 81 is fixed to the inner peripheral surface of the fixed mount 1 such that the outer cylindrical portion 83 is fitted therein.

In the annular space 87 of the rear protective ring 81, a polygonal base plate 9 is formed along the inner peripheral surface of the inner cylindrical portion 85.
1 is inserted. The base plate 91 has its stay 9
3 is screwed and fixed to the rear surface of the fixed cylinder 3, and a polygonal flexible printed board 99 on which electric components 95 to 97 are mounted is attached to the outer peripheral surface. The flexible printed circuit board 99 is formed so as to be continuous with a rotary encoder interposed between the fixed barrel 3 and the zoom cam barrel 21 and a contact point with the camera side formed on the fixed mount 1. The illustration is omitted because the description is complicated. In assembling the lens barrel, after attaching a flexible printed circuit board 99 to a base plate 91 fixed to the fixed barrel 3, the rear protective ring 81 is fitted and fixed to the fixed mount 1.

As described above, in the present embodiment, the portion of the flexible printed circuit board 99 on which the electric components 95 to 97 are mounted is accommodated in the annular space 87 of the rear protection ring 81. The length and outer diameter could be reduced. This makes it possible to reduce the physique and weight of the lens barrel, and even when the lens barrel is mounted on the camera, as shown in FIG. The projection l of the cylinder is smaller than that of the conventional device, and the handling and the like are improved. In FIG. 3, a member denoted by reference numeral 103 is a quick return mirror in the camera, and the entire length of the rear protection ring 81 can be set within a range that does not interfere with the swing locus (shown by a two-dot chain line) of the quick return mirror 103. Further, since the base plate 91 is used for mounting the flexible printed circuit board 99, the attaching work of the flexible printed circuit board 99 becomes extremely easy, and the number of working steps and the like can be greatly reduced.

The description of the specific embodiment has been completed.
Aspects of the present invention are not limited to this embodiment.
For example, in the above embodiment, the present invention is applied to a two-unit zoom lens barrel. However, the present invention may be applied to a lens having three or more lens groups. It may be applied to a single focus lens barrel or the like. Further, in the above embodiment, the polygonal flexible printed circuit board is stuck to the polygonal base plate. However, both may be cylindrical or may be partially flat. Furthermore, the specific configuration and the like of the zoom mechanism and the focus mechanism, including the change of the method of fixing the flexible printed circuit board (such as screwing), are not limited to the examples in the above embodiment.
It can be changed as appropriate according to design reasons.

[0018]

According to the present invention, there is provided a lens barrel having a rear protective ring for protecting an optical lens protruding from a rear end of a lens mount, wherein the rear protective ring has an annular space opened forward. As it is formed, at least a part of the flexible printed board is accommodated in the annular space,
In the flexible printed circuit board, a portion provided in a portion of the lens barrel protruding from the camera is reduced, and an increase in the length of the fixed cylinder due to the flexible printed circuit board is suppressed.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a zoom lens barrel according to an embodiment of the present invention.

FIG. 2 is a half vertical sectional view of a portion different from FIG. 1 of the embodiment.

FIG. 3 is a longitudinal sectional view showing a state where the lens barrel according to the embodiment is mounted on a camera.

[Explanation of symbols]

 1 Fixed mount 3 Fixed cylinder 81 Rear protection ring 83 Stay part 87 Annular space 95-97 Electric parts 99 Flexible printed circuit board 101 Camera body 103 Quick return mirror L ‥‥ optical axis

Claims (4)

[Claims] 1. A lens barrel having a rear protective ring for protecting an optical lens protruding from a rear end of a lens mount, wherein an annular space opened forward is formed in the rear protective ring. A lens barrel wherein at least a part of a flexible printed circuit board is accommodated in an annular space. 2. The lens barrel according to claim 1, wherein an electric component is mounted on a part of the flexible printed circuit board. 3. The lens barrel according to claim 1, wherein the flexible printed circuit board is fixed to an inner peripheral side of the annular space. 4. The lens barrel according to claim 3, wherein said flexible printed circuit board is fixed to an inner peripheral side of said annular space via a metal base plate.