JPS62222225A - Variable focus camera - Google Patents

Abstract

PURPOSE:To obtain a highly reliable camera and to make a lens body tube compact by unitedly moving a photometric optical system and a photographing optical system. CONSTITUTION:The photometric optical system 30 consisting of the 1st photometric optical system including a light emitting element 33 and the 2nd photometric optical system including a light receiving element 31 is formed unitedly with the photographing optical system 1 on a base board 5 in the lens body tube 9 and the optical axis of the optical system 1 is shifted from the center of a front shape of the body tube 9 in either one direction, up or down. At the time of photometric operation, the optical axis of the 1st or 2nd photometric optical system is rotated to scan a subject. The optical system 1 is moved front and back along the optical axis and its focus can be varied. Since the optical system 30 having the 1st and 2nd photometric optical systems is mounted unitedly with the optical system 1 on the base board 5 in the body tube 9, the optical system 30 is moved unitedly with the movement of the optical system 1 at the switching of the focus. Although the optical system 30 mechanically interlocks with the optical system to execute focus adjustment, the system can be applied also to electrical interlocking.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Field of Application The present invention relates to a variable focus camera having a distance measuring optical system of a so-called active autofocus camera and a photographing optical system that can be switched to at least two different focal lengths. .

B. Prior art In conventional variable focus cameras of this type, the distance measuring optical system is fixed to the camera body, and the photographing optical system is fixed and held within a lens barrel that moves in the optical axis direction with respect to the camera body. , the photographing optical system is moved along the optical axis in accordance with the measurement results of the distance measuring optical system, thereby focusing. For this focusing, there are two methods: a method in which the distance measuring optical system and the photographing optical system are mechanically interlocked, and a method in which they are electrically interlocked. In the mechanical interlocking method, for example, a motor moves the photographing optical system, while the same motor rotates the light emitting element of the distance measuring optical system to scan the subject, and the reflected light from the subject is received by, for example, a two-split light receiving element. When the outputs of the light receiving elements match, the driving of the motor is stopped and the photographing optical system is stopped moving out.

In addition, in the electrically linked method, the subject is scanned in the same manner as described above, the rotation angle of the light emitting element is detected when the output of the light receiving element matches, and the photographing optical system is moved a predetermined amount according to the rotation angle. It is fed out by the motor.

C1 Problems to be Solved by the Invention However, variable focus cameras, such as bifocal cameras, have a short focus when the main lens fixedly held in the lens barrel is located close to the film plane, and the main lens When the lens is extended with the lens barrel and the sub-lens is inserted into the optical axis behind it, it becomes a long focal point, so in the case of the mechanical interlocking method described above, the photographic optical system moves linearly and the motor or measuring motor moves rotationally. The connection with the distance optical system was complicated, the number of parts was large, and a relatively large space was required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a variable focus camera that solves the above-mentioned problems by making the distance measuring optical system movable together with the photographing optical system.

Means for solving problem D1 First distance measuring optical system including light emitting element 33 and light receiving element 3
A distance measuring optical system 30 consisting of a second distance measuring optical system including 1 and a photographing optical system 1 are integrally provided on a base plate 5 within a lens barrel 9, and the optical axis of the photographing optical system 1 is aligned with the lens barrel 9. Shift either up or down from the center of the front shape.

During distance measurement, the optical axis of the first or second distance measurement optical system rotates to scan the object. Further, the photographing optical system 1 moves back and forth along the optical axis, and its focus is made variable. Since the distance measuring optical system 30 having the first and second distance measuring optical systems is attached to the base plate 5 in the lens barrel 9 integrally with the photographing optical system 1, when the photographing optical system 1 moves when switching the focus, move as one.

F. Example 1 to 4 show an embodiment of the present invention.

In FIG. 1, which shows a vertical cross section of the lens barrel, a main lens 1 having a three-group structure is held in a holding tube 3 with helicoid screws 3a carved on its outer circumferential surface, and the holding tube 3 is attached to a shutter base 5. It is screwed into the recoid 51. Shutter base 5
A shutter 7 is held at a rear portion 52 of the main lens 1, and a distance measuring optical system 3, which will be described later, is mounted on a holder 53 above the main lens 1.
0 is set.

A shutter base 5 is fixed integrally within the cylindrical lens barrel 9, and a helicoid screw 91 carved on the outer periphery of the lens barrel 9 connects the lens barrel feed tube provided on the outer periphery of the lens barrel 9. The lens barrel 9 itself is prevented from rotating by a rotation preventing member installed upright on the camera body (not shown), and is allowed to move freely in the optical axis direction. Therefore, when the lens barrel feed barrel 11 rotates, the lens barrel 9 moves along the optical axis accordingly. That is, it moves between a retracted position (FIG. 1) during short-focus photography and an extended position (FIG. 2) during long-focus photography. Note that 10 indicates a cover.

Further, the cylindrical portion 5 of the shutter base 5 to which the holding cylinder 3 is screwed
4, an interlocking ring 13 is extrapolated so as to be rotatable about the optical axis of the main lens l. 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 on the shutter base 5.

Further, a cylindrical cam 132 is connected to the interlocking ring 13 .

In FIG. 4, a cam follower 171 of the lever 17, which is rotatable about a rotation center ol, is abuttingly engaged with the cam 132. A pin 172 is provided upright at the other end of the lever 17, and an engaging portion 191 of the lever 19, which is rotatable about the rotation center 02, is engaged with the pin 172. Here, the interlocking ring 13, the motor 15, the lever 17.
19 constitutes a scanning means 40. In addition, the interlocking ring 13
has an engaging arm 133 protruding in front of the camera, which engages with the engaging arm 211 of the back adjustment ring 21 screwed onto the front surface 3b of the holding cylinder 3, as shown in FIG. rotation is transmitted to the holding cylinder 3 via the interlocking ring 13.

Therefore, the interlocking ring 13, the motor 15, and the back adjustment ring 21 constitute a driving means 50 of the imaging optical system.

As shown in FIGS. 1 and 4, the distance measuring optical system 3o is
A light receiving element 31 fixedly held on the shutter base 5, a condensing lens 32 that focuses reflected light (described later) onto the light receiving element 31, a light emitting element 33 fixed to one end of the lever 19, and a light emitting element 33 from one light emitting element 33. It has a light projection lens 34 that emits the emitted light toward the subject.

The light receiving element 31 and the light emitting element 33 are connected to an automatic focus detection circuit 41, the light emitting element 33 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 41 is connected to an arithmetic processing unit (hereinafter referred to as CPU) 42, and a motor drive circuit 43 is connected to the CPU 42 to control the motor 15. In addition,
These detection circuits 41. CPU42. Motor drive circuit 43
Electrical elements such as the following are also integrally held on the shutter base 5.

The operation of the embodiment configured in this way will be explained.

In short-focus photography, as shown in FIG. 1, the lens barrel 9 is in a retracted position within the lens barrel feed barrel 11, and the focal length is determined by the main lens 1. When a shirt button (not shown) is pressed halfway, the motor drive circuit 43 operates in response to a command from the CPU 42, and 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 via the projection lens 34. Then, the rotation of the motor 15 is transmitted to the back adjustment ring 21 via the engagement arms 133 and 211, and the holding cylinder 3 rotates, whereby the main lens 1 is edged out relative to the shutter base 5.

The modulated light irradiated onto the subject is reflected and enters the two-split light receiving element 31 via the condensing lens 32. A pair of light receiving elements 3
Each output from 1 is input to a detection circuit 41 and subjected to well-known signal processing, and the point where the outputs of each light receiving element 31 match is determined to be the in-focus position, and a determination signal is output to the CPU 42.

Next, a motor stop signal is output from the CPU to the motor drive circuit 43, and the motor 15 is stopped. This results in
The holding cylinder 3 stops extending, and the main lens 1 is controlled to a position corresponding to the distance to the subject and is brought into focus.

Next, when the lens barrel feed barrel 11 is rotated by a driving means (not shown), the lens barrel 9 protrudes forward of the camera along the optical axis, and the sub lens 23 is placed on the rear optical axis of the main lens 1.
is inserted, and long-focus photography becomes possible as shown in FIG. As can be seen from FIG. 2, along with the protrusion of the lens barrel 9, a driving means 50 including the main lens 1, a distance measuring optical system 30, a scanning means 40, and a motor 15, which constitutes a photographing optical system.
moves forward as one, so the relative positional relationship of these elements and systems remains the same.In the case of long-focus photography, distance measurement and focus adjustment are performed in the same way as in short-focus photography. The optical design is such that the amount of edge protrusion of the master lens system 1 with respect to the photographing distance is the same in both short-focus photography and long-focus photography. As a result, the same cam can be used.

In the above description, the focus adjustment is performed by mechanically interlocking the distance measuring optical system and the photographing optical system, but the present invention can also be applied to systems in which the distance measuring optical system and the photographing optical system are electrically interlocked. Further, various arrangements of the distance measuring optical system and the photographing optical system can be considered, and they can be shifted horizontally or diagonally. Further, the present invention can also be applied to cameras that can be used by switching the focal length of not only bifocals but also trifocals or more.

G0 Effects of the Invention According to the present invention, the ranging optical system and the photographing optical system move together, so when interlocking these prefectures, in the case of mechanical interlocking, the mechanism is simplified and the number of parts is reduced. reduction of
It contributes to the reduction of occupied space and cost, and in the case of electrical interlocking, it prevents interference between the signal line connecting the electrical elements and the moving part of the photographing optical system, providing a highly reliable camera. Ru. In addition to these effects, the present invention shifts the optical axis of the photographic optical system either up or down with respect to the central axis of the lens barrel that holds the base on which each optical system is attached, so that the lens barrel becomes more compact.

[Brief explanation of drawings]

1 and 2 show an embodiment of the present invention, and are longitudinal cross-sectional views of the front part of the lens barrel, in which FIG. 1 shows the short focus state, FIG. 2 shows the long focus state, and FIG. 3 shows the long focus state. is a front view seen from the line ■-■ in FIG. 1, and FIG. 4 is a perspective view of the area around the ranging optical system 30.
FIG. 2 is a diagram including a block diagram of a focus detection control system. l: Main lens 3: Holding barrel 5: Shutter base 9: Lens barrel 11: Lens barrel feeding barrel 13: Interlocking ring 21: Back adjustment ring 30: Distance measuring optical system 31: Light receiving element 3
Ejection light emitting element 40: Scanning means 50: Driving means ratio Applicant: Nippon Kogaku Kogyo Co., Ltd. Representative Patent Attorney Kieru Nagai Fuyu j Figure 1

Claims (1)

[Scope of Claims] A first distance-measuring optical system including a light-emitting element and a second distance-measuring optical system including a light-receiving element that receives light from the first distance-measuring optical system; The optical axis of the optical system is equipped with a distance measuring optical system that rotates to scan the subject, and measures the distance to the subject based on the light incident on the light receiving element, thereby determining the focal point of the photographing optical system inside the lens barrel. In a variable focus camera capable of focusing by controlling the position and switching between at least two types of focal length by moving the photographing optical system along the photographing optical axis, the first and second distance measuring optical systems; A variable focus camera characterized in that the photographing optical system is integrally provided on a base within the lens barrel, and the optical axis of the photographing optical system is shifted either up or down from the center of the front surface shape of the lens barrel.