JPH08179189A - Movable body slide device for back driving type camera - Google Patents

Abstract

PURPOSE: To provide the constitution of a fixed body by which the tilt of a movable body caused by the posture difference of a camera is restrained so as to straightly advance and support the movable body in the optical axis direction in a back driving type lens interchangeable system camera performing focusing by driving the movable body in the optical axis direction in the fixed body. CONSTITUTION: In a focusing driving mechanism, straight advance guide 9 are at least provided at the opposite angles on the outside of a film aperture part 2a, the movable body 1 and the fixed body 10 are coupled through a focusing driving device 20 at a bottom part so as to smoothly drive the movable body 1 in the optical axis direction, and two straight advance guides 9 consisting of ball slides are provided to be orthogonal in parallel with the horizontal axis and the vertical axis of the front of the camera, then one of screws in the focusing driving device 20 is a compression spring to be a flexible bearing, thereby, the movable body 1 is driven in the optical axis direction to follow the parallelism of the straight advance guide with the optical axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movable body including at least a feeding and holding device including a film opening, a shutter and a body for supporting the shutter, and at least a mount for mounting a photographing lens, a release button and covers. The present invention relates to a back drive type camera configured to connect a fixed body and a movable body with a focusing drive mechanism that drives the movable body in the optical axis direction, and particularly to a straight guide of a slide device that moves the movable body back and forth in the optical axis direction for focusing.

[0002]

2. Description of the Related Art The present applicant has already proposed a focusing drive system for a new camera in Japanese Patent Laid-Open No. 5-173225. This method is auto focus (hereinafter referred to as AF)
The focusing drive mechanism is provided on the camera body side, and in the AF focusing drive, the film feeding and holding mechanism and the film plane receiving portion including the single-lens reflex finder optical system are integrally driven and controlled to the planned focal plane of the subject. That is, the present invention relates to a camera system that moves the camera body to change the distance of the film surface with respect to the taking lens for focusing, and the film feeding and holding mechanism that is the core of the camera with the taking-out mechanism of the taking lens left unchanged. This is a method of driving a movable body, which is integrated with a mirror box and the like, in focus. In the shooting drive of this camera, photometry and distance measurement are calculated by the release of the shooting operation, and focusing drive based on this calculates the movable body in the optical axis direction unlike the conventional shooting lens drive. After focusing, the exposure is completed by a series of sequence operations of the mirror, the diaphragm of the lens, and the shutter, the film is wound up, and one photographing operation is completed. The above-mentioned focusing drive of the movable body of the camera has the same result as that of taking out all the taking lenses, and the advantage of maintaining the lens performance due to the lens barrel configuration of the non-AF lens group can be utilized. Achieve the intended purpose of being able to utilize the system.

The applicant of the present invention has proposed a configuration of a back drive type lens exchange camera in Japanese Patent Application No. 5-143477. In the back-driven lens-interchangeable camera, the film opening (including the mirror box of the single-lens reflex camera) in the center and the finder at the top, the rangefinder module at the bottom, and the film winding underneath. In order to perform rewinding by the same motor, a slider device (in the present invention, which drives the movable body in the optical axis direction) is provided below the body core (the movable body in the present invention) which is connected by a gear train from the spool to the fork in the cartridge chamber. A focus driving device) is disposed, and at least an outer case (fixed body in the present invention) including a release button and a mount for mounting a photographing lens is coupled to the outer case and the movable body is included in the outer case. The above-described structure can be applied not only to a single-lens reflex camera but also to a camera of which the finder is not driven as a back drive type camera.

[0004]

In the back drive type camera, if the fixed body and the movable body are loosely connected by the focusing drive device or if the distance supported by the straight guide member is small, the camera is movable due to the attitude difference of the camera. When the body falls down, the parallelism between the mounting surface of the lens mounting mount on the fixed body side and the film guide rail surface deteriorates, or the distance between the two is changed to improve the image performance of the shooting lens, such as one-sided or out-of-focus points. Inhibit.

The straight guide of the focusing drive mechanism for connecting the fixed body and the movable body is required to have not only looseness but also improved fitting accuracy and durability and impact resistance in order to be smoothly driven, and to satisfy such requirements. It contains the contradictory problem of increasing costs. Further, the fixed body is required to have sufficient rigidity to smoothly drive the movable body.
The fixed body including the movable body is composed of front and rear portions in the optical axis direction and outer shells, but the main body that is the core of the fixed body needs to ensure a drive space for the movable body.

[0006]

The present invention is not limited to single-lens reflex cameras, but it is not limited to single-lens reflex cameras. It is an object of the present invention to solve the above-mentioned problems and to maintain the rigidity of a fixed body as follows. And The movable body is composed of at least a feeding / holding device including a film opening, a shutter and a movable body supporting the shutter, and at least a fixed body composed of a mount for mounting a photographing lens, a release button and covers. In a back drive type camera configured to be connected by a focus drive mechanism so as to be driven forward or backward in a direction, a straight drive guide for focus drive is provided diagonally outside the film opening of the movable body. Provided is a movable body slide device for a back-driven camera.

Further, either the front portion or the rear portion of the fixed body is extended in parallel to the optical axis to the drive range of the movable body to fix the linear guide for focusing drive, and the optical axis of the linear guide support portion is fixed. A front portion or a rear portion of the fixed body is fastened at a direction end surface. Further, the present invention provides a movable body slide device for a back drive type camera, wherein the straight guide is a ball slide.

That is, the main body that serves as the core of the fixed body is divided into two parts, a front body and a rear body made of light metal die-cast, and the movable body is provided with two positions corresponding to diagonal positions outside the film opening (including the mirror box). Extend the front body in the optical axis direction and screw one of the linear guide parts with a screw, and screw the other of the linear guide parts to the light alloy die-cast body that is the core of the movable body, and further attach the rear body to the above. Screw on the straight guide mounting surface and both sides of the front body. The movable body can be smoothly driven in the optical axis direction inside the fixed body through the straight guide. The movable body is pre-loaded with hoisting, rewinding and other functions as a camera.

A focusing drive having the following functions is attached to the fixed body at the bottom of the camera. A screw in which a nut is screwed in the optical axis direction is rotatably supported, and the nut is non-rotatable and can be displaced in the optical axis direction. A motor is fixed near the screw, and a rotation pulse counter for the motor is provided between the screw and the motor by a reduction gear train and a photoreflector. Further, a brush and a substrate on which a gray code is printed are provided between the movable body side and the focusing drive device to enable the position detection of the movable body. Further, the nut is provided with an upper plate having a square hole that fits in the optical axis direction. With the above configuration, the rotation of the motor can drive the movable body in the optical axis direction via the gear train, the screw and the nut, and at the same time, drive control including position detection and fine drive can be performed. The upper and lower covers, the back cover, and the operation dial are screwed to the front and rear bodies, which are the core of the fixed body.

[0010]

According to the structure of the present invention, the tilting of the movable body due to the difference in the attitude of the camera can be suppressed to a minimum, and the front and rear portions of the fixed body are screwed not only on both side surfaces but also above and below the central portion. Therefore, the fixed body becomes rigid, and the movable body can be smoothly driven by the focusing drive mechanism including the straight guide.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a front view in which a main mechanism is arranged in a back drive type AF single-lens reflex camera which is an embodiment of the present invention, FIG. 2 is a longitudinal sectional view taken along the line AA in FIG. 1, and FIG. 3 is a partially enlarged view of FIG. 4 is an enlarged view of the side surface of the straight guide, showing a screwed state. The main configuration of a back-drive AF single-lens reflex camera equipped with the present invention will be described with reference to FIGS. 1, 2 and 3. First, the configurations of the movable body and the fixed body will be described. This camera is configured such that a film feed / holding mechanism on the left and right of a film opening, a portion including a mirror box and a finder (hereinafter referred to as a movable body) drives a motor in the optical axis direction each time focusing is performed. The movable body 1 has a light-alloy die-cast body 2 serving as a support body, and two portions corresponding to diagonal portions of the mirror box in the central portion are planes parallel to each other in the optical axis direction. 6 and a mirror box composed of a finder, a spool 3 having a built-in winding motor, a winding unit 4 including a reduction gear train and an encoder, a one-rotation limiting unit 4a, etc. on the left, and a cartridge 7 for storing a cartridge 7 on the right. The rewinding unit 8 is screwed to the upper part of the chamber. Furthermore, FIG.
Guide straight to the plane parallel to the optical axis in the lower right corner of the mirror box.
And the upper plate of the focusing drive device, which will be described later, is screwed under the central portion. The front body 11 made of a light alloy die-cast, which is a support body of the fixed body 10, has two diagonally opposite corners of the mirror box, which are parallel to the optical axis direction perpendicular to the mounting surface of the lens mount for mounting the photographic lens. , The straight guide 9 is screwed to the upper left of the physique, and the battery 15 is installed on the left bottom.
The lens mount 13 is screwed to the battery chamber or the front surface of the central portion for housing the lens linkage, and the rear surface of the diaphragm linkage 13 is attached to the back surface of the lens mount so as to be rotatable within a certain range.
A diaphragm control unit 14 having a motor is attached to the interface mechanism represented by (1) and the right side thereof.

Next, the focus drive device 20 will be described. The focusing drive device 20 includes a lower plate 21, a front plate 23, and a rear plate 24.
Is fixed with a screw and is composed of another upper plate 22. The screw 25 having the nut 26 screwed into the rear plate 24 with the ball bearing fixed is inserted and protruded, and the gear is screwed to the tip. Further, a focusing drive motor 28 is attached to the rear plate 24, a reduction gear train and a photoreflector for reading a rotation pulse of the motor are attached between the motor 28 and the screw 25, and the rear plate 24 is screwed to the lower plate 21. A ball bearing fitted with a spring receiver is fixed to the front plate 23.
In addition, a compression spring is inserted in the front recess of the screw 25, and the front plate 23 is screwed to the lower plate 21 while inserting and compressing the opposite side of the spring in the recess of the spring receiver. The pressing force load of the compression spring at this time is larger than the load of the movable body. An elongated hole is bored in the lower plate 21 parallel to the optical axis just below the screw 25. Pin 27 is the nut 2
It is fixed at 6. When the motor 28 rotates in the above-described assembly, the nut 26 moves straight along the guide elongated hole.
Further, the substrate on which the gray code is printed is the lower plate 2
Screw to 1. Further, a hole for fitting with the nut 26 in the optical axis direction is opened, and an upper plate 22 having a brush 29 screwed to a portion corresponding to the printed circuit board is prepared.

Next, the assembly of the focusing drive mechanism, the movable body and the fixed body will be described. The lower plate 21 of the focusing drive device is screwed to the bottom of the front body 11 described above. The nut 26 of the focusing device 20 attached to the front body 11 and the hole of the upper plate 22 are fitted to the movable body 1 having the upper plate 22 of the focusing drive device screwed to the lower surface of the central portion of the body 2 described above ( At this time, the upper plate 22 is mounted on the motor 28 and the nut 26 at a position slightly lower than the normal position, as can be seen from FIGS. The straight guides 9 screwed to two diagonal extension portions of the mirror box are screwed to the body 2 and the front body 11, respectively, so that the movable body 1 is in a regular position with respect to the front body. When the focusing drive motor 28 is rotated in the above-described assembly, the movable body 1 can be moved straight in the optical axis direction. Further, a photo reflector for reading the rotation pulse of the motor 28 is used to enable fine drive control in the optical axis direction, and the printed board of the lower plate 21 and the upper plate 2 can be controlled.
The second brush 29 enables the position of the movable body to be recognized.

Next, in the central portion of the fixed body 10, the rear main body 12 is screwed to the bottom of the mirror box of the front main body 11 which extends rearward and diagonally to the outside of the mirror box. Screw on both sides of each other. Further, the covers 16 having an operation member such as a release button are screwed to the front body 11 and the rear body 12 to secure rigidity as a fixed body. Of course, an electric circuit is mounted and wired in the timely process of assembling the camera described above.

Next, a supplementary description will be given of the focusing drive mechanism. As described above, the elements for moving the movable body 1 straight in the direction of the optical axis are three straight guides and screws, and unless the three elements are supported parallel to the direction of the optical axis, the movable body does not swing with respect to the optical axis. Can't be made to go straight, which requires man-hours. In the present invention, as shown in FIG.
In Fig. 5, the left side supports the ball bearings and the right side supports flexibly via compression springs, and the screw 2
5 is biased to the left to absorb the mechanical backlash of the screw 25. Further, since the guide pin 27 fixed to the nut 26 and the elongated hole of the lower plate 21 are loosely fitted, consideration is given so as not to hinder the displacement of the screw 25 in the radial direction.

Further, the straight guide is shown in FIG.
(The surface displayed with) is V of the two U-shaped slide plates
The description has been made using the ball slide connected to the groove by the steel balls held at a constant distance by the retainer, but the single ball slide has different play in the width and thickness directions. The length of the arrow in FIG. 4 conceptually shows the amount of backlash in each direction, and is larger in the width direction. If two straight guides are mounted in the same direction, no matter how accurately they are mounted in parallel, the movable body 1 may fall over the fixed body 10 depending on the camera attitude difference. It cannot be prevented due to the play in the width direction of the slide.
From the viewpoint of the usability of the camera, it is almost impossible to hold it at an angle, so in order to absorb the play of the straight guide 9 due to the ball slide, the two ball slides are orthogonal to the horizontal and vertical positions as shown in FIG. Screwing is performed in the above positional relationship, and replacement is performed under the influence of either one of the width direction play and the thickness direction play, whichever is smaller. Further, if the ball slide is intentionally biased toward one side of the arrow in FIG. 4 (horizontal / vertical), the play can be further reduced. However,
Care must be taken as the load bearing capacity of the ball slide is reduced. In other words, it is sufficient to reduce the backlash in one of the vertical and left and right directions of the straight guide without finishing it to the same accuracy, so that it is sufficient to reduce the ball slide accuracy to only one, and the cost can be reduced.

Another embodiment of the straight guide 9 may be replaced with a device in which the shaft and the cylinder are fitted to each other and both ends of the shaft are fixed to the front main body 11, and the cylinder is fixed to the body 2. The fixation of the shaft and the cylinder may be reversed.

Further, although the support of the screw 25 by the compression spring is biased to one side as can be seen in FIG. 3, the screw 25 is intentionally provided with an expansion / contraction amount in the thrust direction. When the motor 28 is rotated, the screw 25 is rotated so that the nut 26 is guided by the loose fitting of the guide hole 21 of the lower plate and the guide pin 27 of the nut 26 and moves straight in the optical axis direction until finally the front plate 23 or The upper plate 22 (the nut 26 depending on the design) contacts the rear plate 24. In the conventional straight-moving device, the screw and nut bite and the motor torque does not allow the reverse rotation to be performed, which causes a fatal failure that the focus drive cannot be performed.Therefore, the stop is made with a margin from the stop position in the thrust direction. . However, in the device of the present invention, not only the screw is flexibly received by the compression spring, but also the nut 2 in FIG.
In the optical axis leftward drive of 6, even if the motor 22 is further driven after the upper plate 22 comes into contact, the compression spring is further compressed, and there is a margin to operate in the rightward direction in FIG. During this time, the change in the current consumption of the motor is detected, or the stop position by the printed circuit board of the gray code and the brush is detected, or the compression spring is loaded with less friction than the load of the compression spring. A portion of the gear train from the motor 28 to the screw 25 in front of the photoreflector is friction-coupled with each other, and when the compression spring is further contracted, the idling of the motor 28 is detected by the photoreflector and the motor is stopped. For example, the above-mentioned fatal failure can be avoided, and the front plate 23, the rear plate 24, the upper plate 22 (or the nut 26 Also facilitated better correspondingly designed if the ask somewhat leeway in the right direction driven by the inner 3 drive length of which is determined by. The tooth width of the gear is sufficiently set so that the gear screwed on the left side of the screw 25 and the adjacent gear do not come apart by the play in the thrust direction of the screw 25.

Next, a supplementary explanation of the whole will be given. The two linear guides 9 support the movable body 1 at approximately the center of the camera. In addition, the straight guides 9 are arranged diagonally at least outside the film opening 2a at approximately the center of the camera, and the distance at which the straight guides are supported is set to be large. Since the center of gravity of the movable body is incorporated therein, the moment applied to the straight guide is small and the shock resistance is improved. Further, by mounting the two linear guides 9 orthogonally to the horizontal axis and the vertical axis in FIG. 1, a difference in tilting of the movable body 1 (= tilting of the film surface) with respect to the fixed body 10 due to a difference in the attitude of the camera can be considered. I am making it small.

The fixed body 10 has a structure in which the front and rear two main bodies are screwed to the upper and lower sides of the central portion and to both side surfaces, and the covers 16 are attached to the both main bodies. The robustness of the camera is sufficiently maintained even if it is configured to move in any direction.

Although the front body, the rear body and the body are made of light alloy die cast in the embodiment, there is no problem even if plastic is used. Further, although the present invention has been described with respect to the back drive type single-lens reflex camera, the present invention can be widely applied to all back drive type cameras with interchangeable lenses.

As shown in FIG. 2, the movable body 1 is used in the embodiment.
An inner lid is used on the rear surface, and the back lid of the fixed body has a double lid structure. The present applicant has previously proposed this configuration in Japanese Patent Application No. 5-316618, so the description thereof is omitted here.

[0023]

As described above, according to the configuration of the present invention, the following effects can be obtained, which is of high practical value. Two straight guides are provided diagonally including the center of gravity of the movable body. By providing a large straight guide support distance,
Furthermore, since the straight guides are mounted so as to cross at right angles, the play in the width direction and thickness direction of the straight guides can be absorbed to the smaller side, and the tilt of the movable body relative to the fixed body due to the camera attitude difference can be minimized. it can. Also,
As a result, it is possible to reduce the cost of the straight guide.

Furthermore, since the center of gravity of the movable body is taken into a circle whose diameter is equal to the supporting distance of the rectilinear guide, the distance at which the rectilinear guide is supported is increased substantially in the center of the camera. The moment is small,
Improves impact resistance. Further, since the straight guides are arranged diagonally even if the supporting distance is large, the size of the straight guides does not affect the size of the camera.

The main body of the fixed body is 2 in front and back.
Since it is divided and screwed on both sides and the central diagonal part extended for straight guide installation and both sides, the rigidity of the fixed body that includes the movable body and supports the straight drive in the optical axis direction Can be fully satisfied.

As a flexible bearing structure in which one of the screws of the focusing drive device is supported by a ball bearing and the other is supported by a ball bearing and a compression spring, the parallelism with the optical axis of the screw can be rough, and the movable body Since the linear movement in the direction of the optical axis depends on the two linear movement guides, the accuracy of other parts related to the screw and the assembly accuracy can be made rough, and from this aspect the cost can be further reduced and the assembly becomes easier. Great economic effect.

In addition, the support device of the screw compression spring can absorb the inertia of the movable body by the compression spring through the nut when the camera is impacted by being dropped or the like, and the destruction can be prevented.

In the conventional straight-moving device using a screw and a nut, the screw and the nut bite at the drive limit end, and the reverse rotation cannot be performed by the torque of the motor, which causes a fatal failure that the focusing drive cannot be performed. For this reason, a margin is usually added at the front end and the rear end of the drive limit distance, but a biting phenomenon often occurs in confirmation of operation in a state where the software does not work only by the drive device, and thus there is no workability. However, the screw bearing structure using the compression spring of the present invention facilitates the prevention of biting between the screw and the nut due to the contact between the upper plate (or nut) and the screw supporting portion at the end of the motor drive as described above. Also, the set drive distance of the upper plate (or nut) can be fully utilized.

[Brief description of drawings]

FIG. 1 is a front view in which a main mechanism of a back drive type AF single-lens reflex camera is arranged.

FIG. 2 is a vertical sectional view showing a straight guide and a focusing drive device, as seen from the direction of arrow AA in FIG.

3 is a partially enlarged view of FIG. 2 for explaining a support structure for a straight-moving screw.

FIG. 4 is an enlarged view of a side surface of a straight guide (ball slide).

[Explanation of symbols]

 1 movable body 2 body 6 mirror drive unit 9 straight guide 10 fixed body 11 front body 12 rear body 16 covers 20 focusing drive device 21 lower plate 22 upper plate 23 front plate 24 rear plate 25 screw 26 nut 28 for focusing drive motor

Claims (2)

[Claims] 1. A movable body including at least a feeding and holding device including a film opening, a shutter, and a body for supporting the shutter, and a fixed body including at least a photographic lens mounting mount, a release button, and covers. A back drive type camera in which a movable body is connected by a focusing drive mechanism so as to be driven forward or backward in the optical axis direction, wherein the movable body is used for focusing drive diagonally outside the film opening of the movable body. A movable body slide device for a back drive type camera, which is provided with a straight-moving guide. 2. A straight body for focusing drive is fixed by extending either the front portion or the rear portion of the fixed body to the drive range of the movable body in parallel with the optical axis, and the optical axis of the straight guide support portion is fixed. 2. The movable body slide device for a back-driven camera according to claim 1, wherein the front portion or the rear portion of the fixed body is fastened at a direction end surface.