JP3344883B2 - Movable body drive mechanism for back focus control type auto focus camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movable body driving mechanism for an autofocus camera of a back focus control type.

[0002]

2. Description of the Related Art The present applicant divides a camera body into two parts, a fixed body and a movable body, and moves the movable body in the optical axis direction within the fixed body in order to perform autofocus control using a conventional manual lens. Various drive mechanisms have been proposed to bring the film aperture to the focal position. Since the movable body is mounted with a finder mechanism including a film feeding mechanism, a distance measuring mechanism, an exposure mechanism, and the like due to its function, the movable body becomes considerably heavy. In general, in autofocus control, it is required that the focus be brought to a focused point at high speed and with high accuracy. Further, when the movable body is in a stationary state or when it is focused, it is also required that the movable body be reliably held at that position regardless of the posture of the camera.

[0003]

Accordingly, Japanese Patent Application No. 6-169044 (back focus driving mechanism of an auto-focus single-lens reflex camera) and Japanese Patent Application No. 6-169045 (back focus driving type auto-focus single-lens camera) satisfy the above requirements. With the application for a reflex camera control system) and Japanese Patent Application No. 6-200160 (FB drive type autofocus camera film feeder), an ultrasonic wave with a high torque and a low rotation speed and a large holding torque when stationary is used as a drive source for a movable body. It is proposed to use a motor. Although the above-mentioned proposal achieves higher speed and higher accuracy of the movable body, it is necessary to further improve accuracy by eliminating backlash of the drive transmission mechanism.

Further, it is necessary to absorb the impact when the movable body stops at the fixed body, and to remove various effects caused by the impact. Further, there is a demand for a reliable operation of the switch mechanism when the movable body is stopped at the reference position and the position opposite to the movable range, and an easy adjustment and assembly structure during manufacturing. An object of the present invention is to eliminate the backlash of the driving force transmission mechanism to the movable body, reduce the impact when the movable body hits the fixed body,
By applying a contact pressure exceeding a predetermined level to a switch mechanism formed by the movable body hitting the fixed body, it absorbs component variations and rattling, enabling high-speed and accurate autofocus control, and an ultrasonic motor and drive by impact. Back focus control type auto that can prevent the deterioration and destruction of the performance of the system and other camera functions, ensure high-precision detection of both ends of the movable range of the movable body, and stably detect mechanical and electrical positions An object of the present invention is to provide a movable body driving mechanism of a focus camera.

[0005]

In order to achieve the above object, a movable body driving mechanism according to the present invention is arranged at a center of an optical axis passing through a lens, and a fixed body forming an external appearance of a photographing lens mount and a camera. A movable body having a finder mechanism, a distance measuring mechanism, an exposure mechanism, and a film feeding mechanism, the movable body being movable in an optical axis direction in the fixed body by sliding on a slide rail provided on the fixed body; A back focus control type auto that brings a film opening surface of the movable body to a focal position by transmitting a driving force of an ultrasonic motor installed on the fixed body to a rack gear that moves integrally with the movable body via a reduction gear train. A focus camera, wherein a motor ground plate for fixing the ultrasonic motor,
Attachment of the buffer elastic member at a plurality of positions of the fixed body by screwing, and biasing one end of the motor base plate by a first spring member in a direction in which a gear of the reduction gear train is pressed against the rack gear, Further, the ultrasonic motor is fixed by pressing the ultrasonic motor with a second spring material in a direction in which the gear of the ultrasonic motor shaft is pressed against the gear of the reduction gear train. Further, in the above configuration, the present invention is configured such that a limiting plate for limiting one end of the motor ground plate is provided so as not to push the rack gear from a predetermined position by the urging force of the first spring.

Further, the present invention has a fixed lens body for forming the appearance of a photographing lens mount and a camera, and a finder mechanism, a distance measuring mechanism, an exposure mechanism, and a film feeding mechanism disposed at the center of an optical axis passing through the lens. A movable body movable in the optical axis direction within the fixed body by sliding on a slide rail provided on the fixed body, and a driving gear of an ultrasonic motor installed on the fixed body is provided with a reduction gear train. A back focus control type autofocus camera for transmitting a film opening surface of the movable body to a focal position by transmitting the film to a rack gear that moves integrally with the movable body via a first contact point of a switch means on the movable body side. The movable body is movable on the fixed body side facing the movable end on which the movable body is movable. A stopper mechanism also serving as a second contact of the switch means, and both ends of the rack gear are supported by the movable body via a third spring member and a fourth spring member having different spring pressures, respectively; The fourth spring member is disposed between the third spring having a greater spring pressure than that of the fourth spring member and one end of the rack, and is in a fixed state. When the pressing of the rack gear in one direction exceeds the spring pressure of the third spring member, the end of the rack gear contacts and restricts the further movement of the rack gear, and the pressing of the rack gear in the other direction is the second direction. A rack receiving plate for limiting the movement of the end of the fourth spring member when the force exceeds the spring pressure of the fourth spring member, absorbing a shock when the movable body hits the stopper mechanism, and The contact pressure when one contact comes into contact with the second contact of the stopper mechanism to form a switch circuit is equal to or higher than a predetermined value. Further, according to the present invention, in the above configuration, the stopper mechanism has an adjusting mechanism for adjusting a position of the movable body stop.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic cross-sectional view for explaining a relationship between a movable body and a fixed body of a back focus control type camera according to the present invention. A movable body having photographing functions such as a finder mechanism, a distance measuring mechanism, an exposure mechanism, and a film feeding mechanism disposed at the center of an optical axis passing through a lens in a fixed body frame 4 to which the mount base 2 is integrally fixed. The body 3 is housed.
The movable body 3 is slidable in the optical axis direction by being supported and guided by a slide rail mechanism 7 provided on the fixed body 4.

An ultrasonic motor 5 serving as a driving motor is accommodated in a lower cover that is placed over the fixed body frame 4, and a driving force transmitting mechanism 6 a is connected to an output shaft of the ultrasonic motor 5. The driving force transmission mechanism 6a meshes with the rack gear mechanism 6b attached to the movable body 3, and transmits the rotation of the ultrasonic motor 5. These mechanisms bring the film opening surface of the movable body 3 to the focal plane. The interchangeable lens 1 is detachable from the mount base 2.

FIG. 2 is a bottom view showing an embodiment of the movable body driving mechanism of the back focus control type camera according to the present invention. Motor base plate 8 to which ultrasonic motor 9 is fixed
Are fixed to the fixed body frame 4 with the three motor ground plate fixing screws 10.
a, 10b, 10c, the motor base plate receiving rubber 34a,
Attached via 34b, 34c. The motor base plate receiving rubbers 34a, 34b, and 34c have a cylindrical shape in which the outer diameter at the center is smaller than the hole diameter of the motor base plate 8 and the outer diameter at both ends is larger than the hole diameter of the motor base plate 8. The portion is fitted into the hole of the motor base plate 8 so that the motor base plate fixing screws 10a, 10b, and 10c pass through the cylinder (see FIG. 7). Motor ground plate fixing screws 10a, 10b, 1
0c, the motor base plate receiving rubbers 34a, 34b, 34c are sandwiched between the motor base plate 8 and the fixed body frame 4, respectively. Motor base plate receiving rubbers 34a, 34b,
Reference numeral 34c functions as an anti-vibration and sound-proof function and a member that deforms in the direction of backlash removal so that the vibration of the motor base plate 8 is not transmitted to the camera body.

A motor pinion 28 of the output shaft of the ultrasonic motor 9 meshes with a reduction gear 27,
Are engaged with the rack gear 18 (see FIG. 4). The backlash removing mechanism 24 is a mechanism for taking play of engagement between the motor pinion 28, the reduction gear 27, and the rack gear 18. Backlash removal mechanism 24
In order to urge the distal end portion 8a of the motor base plate 8 in the direction of arrow B, a main plate spring restricting plate 20 whose both ends are fixed to the fixed body frame 4 and a motor main plate pressing spring (the 1 spring material) 19. 3A and 3B are views for explaining the details of the backlash removing mechanism of FIG. 2, wherein FIG. 3A is a partial perspective view, and FIG. 3B is a partial plan view of the main plate spring limiting plate with only a limiting end portion left. . The main plate spring limiting plate 20 has bent portions 20a and 20b provided with limiting ends 20c and 20d, respectively.

On the other hand, an abutting portion 8b is provided at the distal end 8a of the motor ground plate 8, and the motor ground plate pressing spring 19 is inserted into the bent portions 20a and 20b of the ground spring limiting plate 20. The fixed body frame 4 is accommodated in a compressed state. Therefore, the tip 8a of the motor base plate 8 is urged in the direction of arrow B. Limiting end 2 of main plate spring limiting plate 20
The reference numerals 0c and 20d are for restricting the biased motor ground plate 8 from moving beyond a predetermined position so that the motor ground plate pressing spring 19 is not pressed with a spring pressure higher than a predetermined value.
The motor pinion 28, the reduction gear 27, and the rack gear 18 are prevented from meshing with each other by excessive pressing.

FIG. 4 is a sectional view taken along the line AA of FIG. 1 showing an embodiment of the movable body driving mechanism of the back focus control type camera according to the present invention. FIG. 6 is a front view, and FIG.
Is a right side view of the same. The rack gear mechanism including the rack support mechanism 45 includes a rack gear 18, a rack spring 25a as a third spring material, and a rack spring 25 as a fourth spring material.
b, a rack receiving plate 26, a rack spring shaft 29, and a rack spring stopper plate 32. The rack spring 25b is
Between the rack spring stopper plate 32 fixed to the movable body 9 and the side surface of the rack gear 18, a shaft extending from the rack gear 18 in a compressed state is fitted. Rack gear 1
8 and the movable body 3 between the rack spring 2
5a is fitted to the rack spring shaft 29 in a compressed state. The tip 26a of the rack receiving plate 26 is the rack gear 1
8 and the rack spring 25a.

FIG. 5 is a detailed view of the vicinity of the tip of the rack receiving plate of the rack gear mechanism. FIG. 5A is a perspective view seen from the back cover direction, FIG. 5B is a perspective view seen from the lens mount direction, and FIG. 5C is a top view. This shows a state in which the side surface of the rack gear 18 abuts against the tip end portion 26a of the rack receiving plate 26 overcoming the spring pressure. Tip portion 26a of rack receiving plate 26
Has a hole 26b, into which the protruding portion 29b of the rack spring shaft 29 enters, and the flange portion 29a is in contact with the side surface of the tip portion 26a by the rack spring 25a. Therefore, the rack gear 18 is not pushed from the position of the distal end portion 26a by the spring pressure of the rack spring 25a.

The spring pressure of the rack spring 25a is
For example, the spring pressure of the former is 3 kg and the spring pressure of the latter is 2 kg. Therefore, the force for driving the rack gear 18 is applied to the rack spring 2.
As long as 1 kg or more is not applied in the direction of arrow 5a (direction of arrow C), the rack gear 18 is in the position of FIG.
It is in the position of (b). However, when a force of 1 kg or more is applied in the direction of arrow C, as shown in FIG.
8 pushes the protruding part 29 b, but is restricted by the tip part 26 a of the rack receiving plate 26. On the other hand, when a force of 2 kg or more is applied in the direction of the rack spring 25b (the direction of arrow D), the rack gear 18 is pushed. This rack support mechanism plays a role of maintaining a frictional effect and shock absorption on the ultrasonic motor and its drive system and applying a contact pressure of a predetermined pressure or more to a switch also serving as the stopper mechanism when the movable body is stopped by the stopper mechanism described below. Fulfill.

Next, a structure for attaching the ultrasonic motor 9 to the motor base plate 8 will be described. The ultrasonic motor 9 has four stepped screws, motor holding screws 31a and 31b (3
1c and 31d are not shown). A thin motor receiving rubber 36 is interposed between the stator 9b of the ultrasonic motor 9 and the motor base plate 8 (FIG. 6).
(See (a) and (b)). The motor receiving rubber 36 is shown in FIG.
Has a circular shape as shown in FIG. At the center of the motor receiving rubber 36, a relief hole 36a for preventing contact with a part of the stator 9b and motor holding screws 31a, 31b, 31 are provided.
Release holes 36b, 36c, 36d, 36 for c and 31d
e is provided.

A pin 33 is implanted on the motor base plate 8, and a fulcrum of the motor pressing spring 30 is fitted to the pin 33. One end of the motor pressing spring 30 is locked by a projection 8c provided on the motor base plate 8, the other end is locked by the stator 9b of the ultrasonic motor 9, and the entire ultrasonic motor 9 is pressed by the reduction gear 27. When the ultrasonic motor 9 is mounted, the backlash between the motor pinion 28 and the reduction gear 27 is removed. Further, even after attachment by the elastic action of the motor receiving rubber 36, the urging force always acts in the direction of removing the backlash between the motor pinion 28 and the reduction gear 27. Motor bearing rubber 36
Are vibration damping functions for absorbing the vibration and sound of the ultrasonic motor 9, absorbing rattling between the ultrasonic motor 9 and the motor ground plate 8, and grounding the ultrasonic motor 9 with the motor holding screws 31a,
When the precision of the motor base plate 8 is not sufficient or when foreign matter such as dust enters the motor, the flatness is maintained so that the stator is not deformed so that the stator is not deformed. It has a function for maintaining a predetermined rotation performance.

Next, a sectional view of the stopper mechanism shown in FIG. 2 and FIG.
A stopper mechanism which also has a switch function will be described with reference to FIG. FIG. 8 is a left side view showing an embodiment of the movable body driving mechanism of the back focus control type camera according to the present invention. Stopper mechanisms 22 and 2 on fixed body frame 4
3 are provided. The stopper mechanisms 22 and 23 give a movable restriction position to the movable body when photographing the near side and the infinity side. Since the stopper mechanisms 22 and 23 have the same structure, the structure of the stopper mechanism 22 will be described. The stopper mechanism 22 includes the adjusting screw 13a and the insulating collar 1.
2a, a contact shaft 11a, an insulating substrate 15a, a screw 14a, and a body stopper set screw 40a.

On the other hand, the body stopper plate 21 of the movable body 3 has a receiving portion 21a that contacts the tip of the contact shaft 11a of the stopper mechanism 22 and a receiving portion 21b that contacts the tip of the contact shaft of the stopper mechanism 23. . The contact shaft 11a of the stopper mechanism 22 is made of a conductive hard metal, and is electrically connected to the pattern formed on the insulating substrate 15a via the screw 14a. Contact shaft 11a and screw 14
a and the adjusting screw 13a are electrically insulated by a resinous insulating collar 12a. When the movable body 3 retreats and moves to the closest distance side by the driving of the ultrasonic motor 9, the receiving portion 21a of the body stop plate 21 abuts against the tip of the contact shaft 11a and stops. The shock at this time is absorbed by the rack support mechanism, and at the same time, contacts with a predetermined contact pressure or more, and the contact pressure is maintained, and the pattern of the receiving portion 21a also serving as a contact on the movable body 3 side and the pattern of the insulating substrate 15a are conducted. That is, at a position where the movable body 3 moves to the shortest distance side and stops, the electric switch is turned on and a signal is output.

Since this stop position determines the flange back position of the camera, it must be set with high accuracy. Therefore, the adjusting screw 13a is screwed into the fixed body frame 4, and the contact shaft 1 is positioned at a position where the movable body 3 should be stopped (accurate flange back position).
When the position 1a is positioned, the adjusting screw 13 is fixed with the body stopper set screw 40a. The tip of the body stopper set screw 40a abuts on the stepped portion of the adjustment screw 13 where the screw is not provided, and stops. In addition, the cell case 41 has a role of pressing one end of the slide rail to restrict the movement of the slide rail.

[0020]

As described above in detail, according to the present invention, the backlash of the driving force transmission mechanism of the movable body of the back focus control type auto focus camera can be eliminated. Further, it is possible to absorb a shock to the ultrasonic motor and its drive system when the movable body is stopped by the stopper mechanism and apply a contact pressure equal to or more than a predetermined pressure to the switch also serving as the stopper mechanism, thereby ensuring a reliable switch function. Therefore, even if there is a part variation and a rattling, these are absorbed, and high-speed and high-precision automatic focus control is enabled. In addition, the performance of the ultrasonic motor, drive system, and other camera functions due to the impact can be prevented from deteriorating and destroyed, and the positions of both ends of the movable range of the movable body can be detected with high accuracy by the position adjusting mechanism of the stopper mechanism. Further, when the motor is driven and stopped, deterioration and breakage of the motor due to inertia can be prevented. Further, there is an effect that the mechanical and electrical positions at the stop position of the movable body can be stably detected.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view for explaining a relationship between a movable body and a fixed body of a back focus control type camera according to the present invention.

FIG. 2 is a bottom view showing an embodiment of a movable body driving mechanism of the back focus control type camera according to the present invention.

FIG. 3 is a diagram for explaining details of a backlash removing mechanism in FIG. 2;

FIG. 4 is an AA sectional view showing an embodiment of a movable body driving mechanism of the back focus control type camera according to the present invention.

FIG. 5 is a view for explaining a part of a rack gear mechanism in detail.

FIG. 6 is a front view showing an embodiment of a movable body driving mechanism of the back focus control type camera according to the present invention.

FIG. 7 is a right side view showing an embodiment of a movable body driving mechanism of the back focus control type camera according to the present invention.

FIG. 8 is a left side view showing an embodiment of a movable body driving mechanism of the back focus control type camera according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Interchangeable lens 2 ... Mount base 3 ... Movable body 4 ... Fixed body frame 5 ... Driving motor (ultrasonic motor) 6a ... Driving force transmission mechanism 6b ... Rack gear mechanism 7 ... Slide rail mechanism 8 ... Motor base plate 9 ... Ultrasonic motor 10a, 10b, 10c ... Motor base plate fixing screw 11a ... Contact shaft 12a ... Insulation collar 13a ... Adjustment screw 14a ... Screw 15a ... Insulating board 16,17 ... Slide rail 18 ... Rack gear 19 ... Motor base plate holding spring 20 ... Base plate spring limiting plate 21a, 21b ... receiving parts 22, 23 ... stopper mechanism 24 ... backlash removing mechanism 25a, 25b ... rack spring 26 ... rack receiving plate 27 ... reduction gear 28 ... motor pinion 29 ... rack spring shaft 35 ... AF module 36 ... motor receiving rubber 37 ... Insulating board 38 ... Adjustment screw 39 ... Screw

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hirotaka Joshi 2-14-9 Tamagawadai, Setagaya-ku, Tokyo Kyocera Corporation Tokyo Yoga Office (56) References JP-A-7-163063 (JP, A) JP-A-8-29657 (JP, A) JP-A-7-98005 (JP, A) JP-A-6-150619 (JP, A) JP-A-6-236660 (JP, A) JP-A-6-317735 ( JP, A) JP-A-63-179345 (JP, A) JP-A-7-235352 (JP, A) JP-A-7-153353 (JP, A) JP-A-1-150826 (JP, A) JP Hei 3-295441 (JP, A) Japanese Utility Model Showa 62-7767 (JP, U) Japanese Utility Model 7-36334 (JP, U) Japanese Utility Model 1-118987 (JP, U) Japanese Utility Model Hei 2-2313 (JP, U) , U) Japanese Utility Model Hei 5-94393 (JP, U)

Claims (4)

(57) [Claims] 1. A fixed body comprising a photographing lens mount and a fixed body forming an appearance of a camera, and a finder mechanism, a distance measuring mechanism, an exposure mechanism, and a film feeding mechanism arranged at the center of an optical axis passing through the lens. A movable body that can move in the optical axis direction within the fixed body by sliding on a slide rail provided on the body, wherein the driving force of an ultrasonic motor installed on the fixed body is reduced via a reduction gear train. A back focus control type auto focus camera for transmitting a film opening surface of the movable body to a focus position by transmitting the film to a rack gear that moves integrally with the movable body, wherein the motor base plate for fixing the ultrasonic motor includes the fixed body. Attach the elastic member for cushioning at a plurality of locations by screwing An end is urged by a first spring member in a direction in which the gears of the reduction gear train are pressed against the rack gear, and the ultrasonic wave is further urged in a direction in which the gears of the ultrasonic motor shaft are pressed against the gears in the reduction gear train. A movable body drive mechanism for a back focus control type auto focus camera, wherein the motor is pressed by a second spring material to fix the ultrasonic motor. 2. The back focus control according to claim 1, further comprising a limiting plate for limiting one end of the motor ground plate so as not to push the rack gear from a predetermined position by the urging force of the first spring. Movable body drive mechanism for autofocus cameras. 3. A fixed body comprising a photographing lens mount and a fixed body forming the appearance of the camera, and a finder mechanism, a distance measuring mechanism, an exposure mechanism, and a film feeding mechanism disposed at the center of an optical axis passing through the lens. A movable body that can move in the optical axis direction within the fixed body by sliding on a slide rail provided on the body, wherein the driving force of an ultrasonic motor installed on the fixed body is reduced via a reduction gear train. A back focus control type autofocus camera for transmitting a film opening surface of the movable body to a focal position by transmitting the film to a rack gear that moves integrally with the movable body, wherein a first contact of a switch unit is provided on the movable body side, On the fixed body side facing the movable end where the movable body is movable, the Provided stopper mechanism serving as a contact point, both ends of the rack gear, the third having different spring pressure, respectively
The third spring member, which is supported by the movable body via a fourth spring member and a fourth spring member, and has a greater spring pressure than the fourth spring member.
And when one direction pressing of the rack gear exceeds the spring pressure of the third spring member, the end of the rack gear hits to limit further movement of the rack gear. And a rack receiving plate for restricting the movement of the end of the fourth spring member when the pressing of the rack gear in the other direction exceeds the spring pressure of the fourth spring member; A back focus which absorbs an impact when hitting a stopper mechanism, and wherein the contact pressure when the first contact contacts the second contact of the stopper mechanism to form a switch circuit is higher than a predetermined value. A movable body drive mechanism for a control type autofocus camera. 4. The movable body driving mechanism according to claim 3, wherein the stopper mechanism has an adjusting mechanism for adjusting a position of the movable body stop.