JPH0618777A - Camera - Google Patents

Abstract

PURPOSE:To secure a space required for housing parts housed in a lens barrel in the lens barrel and to miniaturize a camera body by decentering a center axis extending in the forward and backward moving direction of the lens barrel with respect to the optical axis of a photographing lens. CONSTITUTION:A condensing lens 32 and a light projecting lens 34 are provided with a pair of notched parts which is mutually in parallel on the respective peripheries thereof. By providing such a notched part, a holding body is miniaturized and the lens barrel 9 is suppressed from getting large. A main lens 1 is fitted by decentering the optical axis thereof more downward than the center axis of the lens barrel 9. Thus, the diameter of the lens barrel 9 is prevented from being made large and the space required for housing a range-finding optical system can be expanded. Since the space required for housing the range- finding optical system is obtained in the lens barrel 9 by the decentering of the lens barrel 9, the lens barrel 9 is miniaturized. Thus, not only a mechanism for moving the lens barrel 9 forward and backward in the optical axis direction of the lens 1 but also the camera body can be miniaturized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a camera provided with a lens barrel that can move forward and backward in the optical axis direction of a taking lens.

[0002]

2. Description of the Related Art Conventionally, as a camera of this type, a variable focus camera is known in which the amount of extension of a lens barrel with respect to a camera body is changed to change the focal length of a photographing lens. In this varifocal camera, these arrangements are determined so that the optical axis of the taking lens and the central axis of the lens barrel are aligned, and there is a gap between the outer circumference of the taking lens and the inner peripheral surface of the lens barrel. , Housings in the lens barrel, such as a shutter that also serves as a diaphragm and an actuator of a focus adjustment mechanism, are housed.

[0003]

In the camera described above,
In order to expand the storage space of the storage parts in the lens barrel, it is unavoidable to enlarge the diameter of the lens barrel, but since the storage parts in the lens barrel are biased to specific locations on the outer periphery of the taking lens, The diameter of the lens barrel is increased only for some of the components stored in the lens barrel, and a large amount of wasted space is generated at a position where the components stored in the lens barrel cannot be inserted. If the lens barrel becomes large, it is inevitable that the driving mechanism for moving the lens barrel in the direction of the optical axis of the taking lens also becomes large, which is a major obstacle to downsizing the camera body.

An object of the present invention is to provide a camera in which the size of the lens barrel can be prevented and the space required for housing the components stored in the lens barrel can be secured in the lens barrel to reduce the size of the camera body. Especially.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 showing an embodiment, the present invention is applied to a camera having a lens barrel 9 which can move forward and backward along the optical axis of a taking lens 1. . Then, the central axis extending in the advancing / retreating direction of the lens barrel 9 is decentered with respect to the optical axis of the photographing lens 1 to achieve the above-mentioned object.

[0006]

A large space suitable for housing the lens barrel housing component 30 can be provided on the eccentric side of the center axis of the lens barrel 9 without increasing the size of the lens barrel 9.

Incidentally, in the section of means and action for solving the above problems for explaining the constitution of the present invention, the drawings of the embodiments are used for making the present invention easy to understand. It is not limited to.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 4 show an embodiment of the present invention.
In FIG. 1 showing a longitudinal section of a lens barrel portion, a main lens 1 of a three-group structure is held by a holding barrel 3 having an outer peripheral surface engraved with a helicoid screw 3a.
It is screwed to the helicoid 51. The shutter base 5 holds the shutter 7 at the rear portion 52 of the main lens 1,
A distance measuring optical system 30, which will be described later, is attached to the holder 53 above the main lens 1.
Is provided.

A shutter base 5 is integrally fixed to the inside of the cylindrical lens barrel 9, and a helicoid screw 91 engraved on the outer periphery of the lens barrel 9 is provided on the outer periphery of the lens barrel 9. The lens barrel 9 itself is screwed with the helicoid screw 111 of the barrel feed barrel 11, and its rotation is blocked by a rotation blocking member provided upright on the camera body (not shown).
In addition, the movement in the optical axis direction is free, and accordingly, when the lens barrel feed tube 11 rotates, the lens barrel 9 moves accordingly along the optical axis. That is, it moves between the retracted position (FIG. 1) during short focus shooting and the protruding position (FIG. 2) during long focus shooting. In addition, 10 shows a cover.

Further, the interlocking ring 13 is externally inserted into the cylindrical portion 54 of the shutter base 5 to which the holding cylinder 3 is screwed so as to be rotatable around the optical axis of the main lens 1. As shown in FIG. 4, a motor 15 having a gear 151 that meshes with a gear 131 formed on the interlocking ring 13 is held by the shutter base 5. Further, the interlocking ring 13 has a cylindrical cam 132.
Are lined up.

In FIG. 4, the cam follower 171 of the lever 17, which is rotatable about the rotation center O1, is the cam 1.
32 is abuttingly engaged. A pin 172 is provided upright on the other end of the lever 17, and an engaging portion 191 of the lever 19 which is rotatable about a rotation center O2 is engaged with the pin 172. Here, the interlocking ring 13, the motor 15, and the levers 17 and 19 constitute the scanning means 40. Further, the interlocking ring 13 has an engaging arm 133 protruding from the front of the camera, and as shown in FIG. 3, engages with the engaging arm 211 of the back adjusting ring 21 screwed to the front surface 3b of the holding cylinder 3. Then, the rotation of the motor 15 is transmitted to the holding cylinder 3 via the interlocking ring 13. The interlocking ring 13, the motor 15, and the back adjustment ring 21 constitute the driving means 50 of the photographing optical system.

As shown in FIGS. 1 and 4, the distance measuring optical system 30 includes a light receiving element 31 fixedly held on the shutter base 5.
And a condenser lens 32 for condensing reflected light described below on the light receiving element 31, and a light emitting element 33 fixed to one end of the lever 19.
And a light projecting lens 34 that emits light emitted from the light emitting element 33 toward a subject. As shown in FIG. 3, the condensing lens 32 and the light projecting lens 34 are provided with a pair of notches 32a and 34a which are parallel to each other on their peripheral edges. By providing these cutout portions 32a and 34a, the holder 5
3 is downsized, and the diameter of the lens barrel 9 is suppressed from increasing.
In FIG. 4, both the condenser lens 32 and the light projecting lens 34 are drawn in a circular shape for simplification.

As is clear from FIGS. 1 and 3, the main lens 1 is mounted with its optical axis decentered below the central axis of the lens barrel 9. This allows
The storage space for the distance measuring optical system 30 can be expanded while preventing the lens barrel 9 from increasing in diameter. The light receiving element 31 and the light emitting element 33 are connected to the automatic focus detection circuit 41, and the light emitting element 3
3 is controlled to emit modulated light, and distance measurement is performed based on the output signal of the light receiving element 31. The detection circuit 4
1 is connected to an arithmetic processing unit (hereinafter, CPU) 42, and C
The motor drive circuit 43 follows the PU 42 and the motor 1
5 is controlled. The detection circuit 41 and the CPU 4
2, electric elements such as the motor drive circuit 43 are also the shutter base 5
Are held together.

The operation of the embodiment thus configured will be described. In short-focus photography, as shown in FIG. 1, the lens barrel 9
Is in the retracted position in the lens barrel feed tube 11, and the main lens 1
Determines the focal length. When a shutter button (not shown) is half-depressed, a motor drive circuit 43 operates in response to a command from the CPU 42, the motor 15 starts rotating, and the detection circuit 41 causes the light emitting element 33 to emit modulated light. In FIG. 4, when the motor 15 rotates counterclockwise, the interlocking ring 13 rotates clockwise and the lever 17 rotates counterclockwise. When the lever 19 rotates clockwise in conjunction with the lever 17, the light emitting element 33 also rotates clockwise, and the subject is scanned by the modulated light through the light projecting lens 34.
Then, the rotation of the motor 15 is transmitted to the back adjusting ring 21 via the engaging arms 133 and 211 to rotate the holding barrel 3, whereby the main lens 1 is extended to the shutter base 5.

The modulated light emitted to the subject is reflected and enters the two-divided light receiving element 31 through the condenser lens 32. The respective outputs from the pair of light receiving elements 31 are input to the detection circuit 41 and subjected to known signal processing. The point where the outputs of the respective light receiving elements 31 coincide is discriminated as the in-focus position and a discrimination signal is outputted to the CPU 42. It Then, the CPU outputs a motor stop signal to the motor drive circuit 43 to stop the motor 15.
As a result, the extension of the holding tube 3 is stopped, and the main lens 1 is controlled to a position according to the distance to the subject and focused.

Next, the lens barrel 9 in which the lens barrel feed barrel 11 is rotated by a driving means (not shown) protrudes forward of the camera along the optical axis, and the auxiliary lens 23 is attached to the rear optical axis of the main lens 1. After being inserted, as shown in FIG. 2, long focus photography becomes possible. As can be seen from FIG. 2, the main lens 1, which constitutes the photographing optical system together with the projection of the lens barrel 9,
Since the distance measuring optical system 30, the scanning means 40, and the driving means 50 including the motor 15 move forward integrally, the relative positional relationship among these elements and systems does not change. In the case of long-focus shooting, distance measurement and focus adjustment are performed in the same manner as short-focus shooting. In both cases of short-focus shooting and long-focus shooting, the amount of extension of the main lens 1 with respect to the shooting distance is optically designed to be the same. As a result, the same cam can be used.

As described above, in this embodiment, the eccentricity of the lens barrel 9 provides the space necessary for housing the distance measuring optical system 30 in the lens barrel 9, so that the lens barrel 9 and The lens barrel 9 is downsized as compared with the conventional example in which the lens 1 and the lens 1 are coaxial. As a result, the mechanism for moving the lens barrel 9 forward and backward in the optical axis direction of the main lens 1 is also downsized, and the camera body is downsized.

In the embodiment, the distance measuring optical system 30 is housed in the space enlarged due to the eccentricity between the optical axis of the main lens 1 and the central axis of the lens barrel 9, but the present invention is not limited to this. When the distance measuring optical system 30 is not housed in the lens barrel 9, instead of this, other housing components in the lens barrel, for example, the shutter base 5 may be housed in an eccentrically enlarged space. The present invention can be applied not only to a bifocal camera, but also to a monofocal camera or a trifocal camera or more as long as the lens barrel advances and retracts.

[0019]

As described above, according to the present invention, the central axis of the lens barrel is eccentric with respect to the optical axis of the photographing lens, so that the lens barrel can be prevented from being upsized and the parts to be housed in the barrel can be prevented. It is possible to secure the space required for housing the inside of the lens barrel to reduce the size of the camera body.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a front portion of a lens barrel at a short focal length of a camera according to an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the front part of the lens barrel at the time of long focus of the camera of one embodiment of the present invention.

FIG. 3 is a front view seen from the line III-III in FIG.

FIG. 4 is a view of the periphery of a distance measuring optical system 30, including a block diagram of a focus detection control system.

[Explanation of symbols]

 1 Main Lens 3 Holding Cylinder 5 Shutter Base 9 Lens Barrel 11 Lens Cylinder Feeding Cylinder 13 Interlocking Ring 21 Back Adjusting Ring 30 Distance Measuring Optical System 31 Light Receiving Element 33 Light Emitting Element 40 Scanning Means 50 Driving Means

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 7316-2K G03B 3/00 A

Claims (1)

[Claims] 1. A camera having a lens barrel capable of advancing and retracting along the optical axis of a taking lens, wherein a central axis extending in the advancing and retracting direction of the lens barrel is decentered with respect to the optical axis of the taking lens. Characteristic camera.