JP3547258B2 - Photographic optics - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a photographing optical device mainly mounted on a camera or the like, and more particularly to a gear tooth jump prevention mechanism used for driving a photographing optical system.
[0002]
[Prior art]
Conventionally, gears have been used as a means for transmitting a driving force from a driving source when the lens group is driven during focusing or zooming of the imaging optical system. For example, as schematically shown in FIG. 11, when the drive gear 51 rotates in the direction of arrow A, the movement is transmitted to a gear 53 provided on a member for driving the lens group by meshing of the teeth, and the gear 53 Is driven in the direction of arrow B. A stopper 54 is provided at the end of the drive destination, and stops when the gear 53 comes into contact with the stopper 54. When the rotation of the drive gear 51 is also stopped by the stop of the gear portion 53, the stop of the rotation is detected by some means, and the drive of the drive gear 51 is stopped.
[0003]
[Problems to be solved by the invention]
However, in the above-described configuration, an unreasonable force is applied and the bearing of the rotating shaft 52 is swung in the direction of arrow C or the like until the rotation of the driving gear 51 is detected and the driving is stopped. In some cases, tooth jump may occur between the drive gear 51 and the gear portion 53. SUMMARY OF THE INVENTION The present invention provides a photographing optical device that solves the above-described disadvantages and that can reliably drive the gear used for driving the photographing optical system by providing a gear skip prevention mechanism. The purpose is to do.
[0004]
[Means for Solving the Problems]
To achieve the above object, the present invention, the drive gear forming part of the drive means, when driving meshing gear portion partially provided circumferentially member for driving the lens groups, see engage Within the fitting range, the gear unit is provided integrally with a member that drives the lens group, and is provided on a side opposite to the gear unit with respect to the drive gear so as to form a concentric circle with the gear unit. And a restraining member for suppressing the shift in the opposite direction due to being pushed by the second member. Further, the suppression member is provided so as to bridge between support members provided at both ends of the gear portion.
[0005]
In addition, a bearing portion for the drive gear is further provided, and the bearing portion and the restraining member are brought close to or in contact with each other, thereby guiding the gear portion and the drive gear so as not to be disengaged.
[0006]
Furthermore, by adopting a configuration in which the bearing portion is provided on a fixed cylinder disposed on the outer periphery of a member that drives the lens group, rattling of the drive gear is prevented, and the lens group is reliably driven. I do.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the appearance of a camera in which an interchangeable lens 61 as a photographing optical device to which the present invention is applied is attached to a camera body 60. FIG. 2 is a perspective view schematically illustrating a state in which main components of the photographing optical device of the embodiment are disassembled and arranged in the optical axis direction. In FIG. 1, reference numeral 1 denotes a first moving frame disposed at the front of the photographing optical apparatus, and 2 denotes a second moving frame, in which lens groups L1 and L2 (not shown) are held, respectively. I have. Reference numeral 3 denotes a cam cylinder. The first moving frame 1 and the second moving frame 2 are fitted inside the cam cylinder 3, and pins 5 and 6 provided on the cam cylinder 3 are spirally provided on the cam cylinder 3. It penetrates the cam grooves 7 and 8 respectively.
[0008]
Reference numeral 9 denotes a fixed cylinder, and 10 denotes a cam groove linearly provided in the fixed cylinder 9. The cam cylinder 3 is fitted into the fixed cylinder 9 and the pins 5 penetrate the cam grooves 7, 8. 6 further penetrates the cam groove 10. Reference numeral 4 denotes a holding ring, 11 denotes a motor unit having a built-in motor and a driving gear 15 rotated by the motor, and 12 denotes a cover for covering the rear part of the photographing optical device. In addition, an external member for covering the cam groove 10 is provided on the outer periphery of the fixed cylinder 9, but is omitted in the drawing.
[0009]
FIG. 3 is a longitudinal sectional view schematically showing a state where the photographing optical device is assembled, and FIG. 4 is a longitudinal sectional view schematically showing a state where the lens group is driven. In FIG. 3, when the drive gear 15 is driven by the motor unit 11, the inner gear 16 provided partially on the inner surface of the cam barrel 3 is driven to mesh with the cam barrel 3, and the cam barrel 3 rotates about the optical axis X.
[0010]
At this time, the cam grooves 7 and 8 provided spirally in the cam barrel 3 push the pins 5 and 6 provided in the first moving frame 1 and the second moving frame 2 respectively, and the pins 5 and 6 are fixed. Since the first moving frame 1 and the second moving frame 2 are moved in the optical axis direction, as shown in FIG. 4, the lens groups L1 and L2 are moved. Driven similarly. At this time, the amount of movement between the first moving frame 1 and the second moving frame 2 is different based on the difference in the shape of the cam grooves 7 and 8, and therefore, as shown in FIG. The interval will open.
[0011]
FIG. 5 is a diagram schematically showing the state near the drive gear 15 from the optical axis direction. A cover 18 provided on a bearing 17 extending from the fixed cylinder 9 comes into contact with stoppers 19 provided at both ends of the inner gear 16, thereby functioning to stop the operation of the inner gear 16 and the rotation of the cam cylinder 3. In addition, it has a role of protecting the drive gear 15. Reference numeral 20 denotes a sliding member which is provided integrally with the cam cylinder 3 so as to be bridged between the stoppers 19, 19, and comes into contact with the bearing 17 when the driving gear 15 is lifted to allow the driving gear 15 to escape. To prevent. When the cam barrel 3 rotates, the sliding member 20 has a bow shape concentric with the fixed barrel 9 in order to maintain the close relationship with the bearing 17. Although the sliding member 20 is close to the bearing 17 in FIG. 5, the sliding member 20 may be always in contact with the bearing 17.
[0012]
FIG. 6 is a perspective view schematically showing a state in which stoppers 19 that come into contact with the bearings 17 are provided at both ends of the inner gear 16. In the figure, when the drive gear 15 is driven by the motor unit 11 and rotates in the direction of arrow A, the inner gear 16 meshes and drives in the direction of arrow B. Then, when driven to the end, as shown in FIG. 7, the stopper 19 comes into contact with the bearing 17, a force canceling each other acts as shown by an arrow, and the inner gear 16 stops. At this time, since the bearing 17 does not swing to the right in the drawing, tooth jump does not occur.
[0013]
This is the same when the drive gear 15 rotates in the opposite direction, the inner gear 16 moves in the direction opposite to the direction of arrow B, and comes into contact with the stopper 19 at the end. When the stopper 19 comes into contact with the bearing 17 and the inner gear 16 stops, a force for stopping the drive gear 15 is applied, and the drive gear 15 stops. When this stop is detected by the detecting means (not shown), the motor drive signal is not supplied, and the drive of the motor (and the drive gear 15) stops.
[0014]
FIG. 8 shows a case where a sliding member 20 is further provided. In this case, similarly, when the drive gear 15 is driven by the motor unit 11 and rotates in the direction of arrow A, the inner gear 16 meshes and drives in the direction of arrow B. At this time, the bearing 17 and the sliding member 20 are close to or in contact with each other. Further, as shown in FIG. 9, at the time of driving, the driving gear 15 receives a force F due to the reaction from the inner gear 16, and considering the component forces Fy and Fx, Fy is the force in the direction in which the gears are disengaged. And Fx is expressed as a reaction of a force driving the inner gear 16 in the longitudinal direction. Normally, the component forces Fy and Fx are absorbed by the bearing 17.
[0015]
At this time, if the user of the camera forcibly stops the inner gear 16 by applying some external force or the like, since the driving force is continuously applied to the driving gear 15, the force F increases and the component force Fy also increases. Therefore, it cannot be absorbed only by the bearing 17, and there is a possibility that the meshing of the gears may be disengaged and the teeth may jump. If the sliding member 20 is present, the bearings 17 come into contact with each other, as shown in FIG. 10, so that the forces cancel each other as shown by arrows. Therefore, the component force Fy is absorbed to prevent tooth jump. Can be.
[0016]
In this example, when the inner gear 16 is driven to the end portion, the component force Fx is absorbed by contacting the inner gear 16 with an external stopper instead of contacting the bearing 17 with the stopper 19. You may go. This is because, as long as the sliding member 20 is present, there is no risk of tooth jumping even at the end portion. The photographing optical system can be reliably driven by the above-described tooth skipping prevention mechanism.
[0017]
【The invention's effect】
As described above, according to the present invention, a gear used for driving a photographing optical system is provided with a tooth skipping prevention mechanism, thereby providing a photographing optical device capable of reliably driving. Can be. And its tooth-skipping prevention mechanism, the drive gear forming part of the drive means, when driving meshing gear portion partially provided circumferentially member for driving the lens groups, within each other viewed mesh Is provided integrally with a member for driving the lens group, on the opposite side to the gear portion with respect to the drive gear, so as to form a concentric circle with the gear portion, and the drive gear is pushed by the gear portion. This is to provide a suppressing member for suppressing the shift in the opposite direction.
[0018]
Further, in the photographing optical device according to the fourth aspect, the bearing portion is provided on a fixed cylinder disposed on an outer periphery of a member for driving the lens group, thereby preventing rattling of the driving gear. Then, the lens group is reliably driven.
[Brief description of the drawings]
FIG. 1 is a perspective view showing the appearance of a camera to which a photographing optical device according to the present invention is attached.
FIG. 2 is an exploded perspective view of main components constituting the photographing optical device of the present invention.
FIG. 3 is a vertical cross-sectional view schematically showing a state in which an imaging optical system is assembled.
FIG. 4 is a longitudinal sectional view schematically showing a state in which a lens group is driven.
FIG. 5 is a diagram schematically showing a state near a driving gear from an optical axis direction.
FIG. 6 is a perspective view schematically showing a state in which a stopper that comes into contact with a bearing is provided.
FIG. 7 is a view schematically showing a state in which a stopper is in contact with a bearing.
FIG. 8 is a perspective view schematically showing a state in which a sliding member is provided to approach or abut the bearing.
FIG. 9 is an explanatory diagram of a force applied to a drive gear.
FIG. 10 is a view schematically showing a state in which a sliding member is in contact with a bearing.
FIG. 11 is a diagram schematically showing a conventional gear driving state.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 1st moving frame 2 2nd moving frame L1, L2 Lens group 3 Cam cylinder 4 Holding ring 5, 6 Pins 7, 8, 10 Cam groove 9 Fixed cylinder 11 Motor unit 12 Cover 15 Drive gear 16 Inner gear 17 Bearing 18 Cover 19 Stopper 20 Sliding member

Claims (4)

A photographing optical system, a first holding member that holds the photographing optical system, and a first holding member that holds the first holding member, and that is itself driven during focusing or zooming of the photographing optical system, so that the first holding member is moved. In a photographing optical apparatus comprising: a second holding member that is driven in an optical axis direction of the photographing optical system; and a driving unit that drives the second holding member, the second holding member is driven by a driving gear that forms a part of the driving unit. when driving meshing gear portion partially provided in the circumferential direction of the holding member, within each other viewed engage, be integral with the second holding member, opposite to the gear portion with respect to said driving gear A photographing optical device, further comprising a constraining member that is provided so as to be concentric with the gear portion and that suppresses the drive gear from being pushed by the gear portion and shifted in the opposite direction. The photographing optical device according to claim 1, wherein the suppression member is provided so as to bridge between support members provided at both ends of the gear portion. The photographing optical device according to claim 1, further comprising a bearing portion for the drive gear, wherein the bearing portion and the suppressing member are brought close to or in contact with each other. The photographing optical device according to claim 3, wherein the bearing portion is provided on a fixed cylinder disposed on an outer periphery of the second holding member.

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