JP4153737B2 - Full-time manual lens barrel - Google Patents

Description

[0001]
【Technical field】
The present invention relates to a full-time manual lens barrel capable of selecting auto focus and manual focus without performing a special switching operation.
[0002]
[Prior art and its problems]
In still cameras and video cameras, lens barrels that include both motor-driven autofocus (AF) and manual focus (MF) operation systems are widely used. Conventionally, in this type of camera, a mechanical power transmission switching mechanism (clutch mechanism) is provided between the AF drive system and MF operation system and the focus lens, and this switching mechanism is operated to operate an autofocus mode and a manual focus mode. Was selected. However, for the purpose of simplifying the structure and improving operability, a so-called full-time manual focus mechanism (hereinafter referred to as a full-time manual mechanism) is proposed in which auto focus and manual focus can be selected without performing a special switching operation. Has been.
[0003]
For example, in Japanese Patent No. 2768490, an MF ring for manual focus operation and an optical axis between two opposed end surfaces of an annular AF vibration wave motor (ultrasonic motor) provided around the optical axis A full-time manual mechanism has been proposed in which a roller that can rotate (spin) around an orthogonal rotation axis is sandwiched. This roller is provided on a focus lens drive ring that can rotate coaxially with the MF ring and the rotor. When one of the MF ring and the rotor is rotated, the roller rotates around the other MF ring or the end surface of the rotor. By rotating in the direction, the focus lens drive ring is turned. In order to perform such an operation, a predetermined contact pressure (frictional force) is required between the MF ring, each facing end surface of the rotor, and the roller. Contact pressure is applied by an urging spring (disc spring) that presses in the axial direction. However, since this biasing spring is provided in an annular shape centering on the optical axis in correspondence with the stator of the vibration wave motor, it is large and causes a large dead space in the lens barrel. Further, there is a drawback that the AF drive source cannot be applied to a type in which the AF drive source is not a vibration wave motor in the lens barrel but a motor provided in the camera body.
[0004]
OBJECT OF THE INVENTION
An object of the present invention is to provide a full-time manual lens barrel that has a simple structure, is space efficient, and can be configured regardless of the mode of AF driving.
[0005]
SUMMARY OF THE INVENTION
The full-time manual lens barrel of the present invention has a lens driving ring that moves the focus lens group in the optical axis direction by rotation about the optical axis; a lens that is coaxial with the lens driving ring and independently rotatable. An MF ring supported on the outer surface of the lens barrel and an AF ring rotated by an internal driving means; an optical axis direction formed on each of the AF ring and the MF ring as a part of a conical surface centered on the optical axis. A pair of annular tapered surfaces that are spaced apart from each other; a roller support shaft that projects from the lens drive ring in an outer diameter direction perpendicular to the optical axis; and that can rotate about the roller support shaft and move along the roller support shaft A taper roller surface that is supported and forms a part of a conical surface centering on the roller support shaft and that contacts each annular taper surface of the AF ring and the MF ring, and the taper roller surface and the pair of annular taper surfaces In contact A rotation transmission roller in which movement in the direction along the roller support shaft is restricted; a roller retaining portion provided at the tip of the roller support shaft; inserted between the roller retaining portion and the rotation transmission roller, the rotation An urging member that urges the transmission roller in a contact direction with the pair of annular tapered surfaces; and an urging force of the urging member against the rotation transmission roller by changing a distance between the roller retaining portion and the rotation transmission roller. varying the contact pressure adjusting means for adjusting the contact pressure of the tapered roller surface of the rotation conveying roller with respect to the ring-shaped tapered face of the AF ring and MF ring; provided with, when rotated to one of the AF ring and MF ring The rotation transmission roller rolls on the other annular tapered surface of the AF ring and the MF ring, and the lens driving ring is rotated without rotating the other AF ring or MF ring. Yes.
[0006]
The urging member provided between the roller retaining portion and the rotation transmission roller is preferably an annular spring centered on the roller support shaft.
[0007]
In the full-time manual lens barrel of the present invention, the AF ring can be a rotor of a vibration wave motor having an annular shape around the optical axis. Alternatively, the present invention can be applied to a lens barrel that rotates the AF ring by a built-in motor of the camera body.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a first embodiment of a full-time manual lens barrel of the present invention. A fixed ring 11 fixed to the camera body via a mount portion (not shown) is provided in the lens barrel, and a cam ring 12 is rotatably supported on the outer peripheral surface of the fixed ring 11. The lens frame 13 that supports the focus lens group FL has a cam pin 14 that protrudes in the outer diameter direction. The cam pin 14 passes through a rectilinear guide groove 15 formed in the fixed ring 11, and the inner periphery of the cam ring 12. It engages with a bottomed cam groove 16 formed on the surface. In addition to the focus lens group FL, a lens group (not shown) constituting the objective optical system is provided in the lens barrel. Further, FIG. 1 shows only main parts related to the description of the present invention, and illustration of an exterior member of the lens barrel, a mount part to the camera body, and the like is omitted.
[0009]
The rectilinear guide groove 15 is formed in parallel with the optical axis O of the objective optical system including the focus lens group FL, and the lens frame 13 goes straight in the optical axis direction due to the engagement relationship between the rectilinear guide groove 15 and the cam pin 14. Guided. On the other hand, the cam groove 16 into which the tip of the cam pin 14 is fitted has a predetermined locus inclined with respect to the optical axis O, and the cam ring 12 having the cam groove 16 is centered on the optical axis O. It is supported by the outer peripheral surface of the fixed ring 11 so that rotation is possible. Therefore, when the cam ring 12 rotates, the lens frame 13 moves in the optical axis direction according to the locus of the cam groove 16.
[0010]
Focusing is executed by the movement of the lens frame 13 (focus lens group FL) in the optical axis direction. The cam ring 12 for moving the lens frame 13 is manually moved and positioned on the outer surface of the lens barrel. It can be provided by two systems of an MF ring (manual focus operation ring) 20 that can be rotated and an AF motor 21 in the lens barrel. The manual focus operation by the MF ring 20 and the autofocus operation by the AF motor 21 can be selected without performing a special switching operation. The specific mechanism will be described below.
[0011]
Two screw portions 22 and 25 are formed on the outer peripheral surface of the fixed ring 11 near the front end portion and the rear end portion in the optical axis direction, and the front retaining ring 23 is screwed to the front screw portion 22. Has been. The front retaining ring 23 has a holding recess 24 that supports the front end portion of the MF ring 20, and the MF ring 20 is supported so as to be rotatable about the optical axis O by the engagement relationship with the holding recess 24. Yes. The cam ring 12 has its front end abutted against the front retaining ring 23 and its rear end abutted against the outer flange portion 11a of the fixed ring 11 so that the movement in the optical axis direction is restricted. It is supported so that it can rotate only at a fixed position around the center. On the other hand, a rear retaining ring 26 is screwed to the screw portion 25 behind the fixed ring 11, and the AF motor 21 is supported on the front portion of the rear retaining ring 26. The AF motor 21 is a vibration wave (ultrasonic wave) motor having an annular shape around the optical axis O. The stator 21a is fixed to the outer peripheral surface of the fixed ring 11, and the optical axis O is positioned in front of the stator 21a. It has a rotatable rotor 21b (AF driving ring) as a center. The inner diameter portion of the rotor 21b is supported on the outer peripheral surface of the outer flange portion 11a.
[0012]
A pair of annular tapered surfaces 30 and 31 facing each other in the optical axis direction are formed on the rear end portion of the MF ring 20 and the front end portion of the rotor 21b. Each of the annular tapered surfaces 30 and 31 forms a part of a conical surface with the optical axis O as the center, and is substantially symmetrical with respect to a virtual plane PA orthogonal to the optical axis O. That is, the annular taper surface 30 on the MF ring 20 side is a part of a conical surface whose apex is located on the image surface (back side of the optical axis) side than the bottom surface, and the annular taper surface 31 on the rotor 21b side is conversely The apex is a part of a conical surface located closer to the subject (front side of the optical axis) than the bottom surface, and the generatrix of each conical surface is inclined at the same angle in the opposite direction to the virtual plane PA.
[0013]
Near the rear end of the cam ring 12, a roller support shaft 42 protrudes in an outer diameter direction orthogonal to the optical axis O via an advance / retreat screw portion 41, and rotates around the outer peripheral surface of the roller support shaft 42. The motion transmission roller 40 is supported. The rotation transmitting roller 40 is rotatable about the roller support shaft 42 and is movable in the axial direction of the roller support shaft 42, and contacts the annular tapered surface 30 and the annular tapered surface 31 at a lower portion thereof. A tapered roller surface 43 is provided. The taper roller surface 43 is formed as a part of a conical surface centering on the rotation axis of the rotation transmission roller 40 (the axis of the roller support shaft 42). As shown in FIG. The tapered surface 30 and the annular tapered surface 31 are in contact with each other in a linear region. An annular disc spring (biasing member) 46 centering on the roller support shaft 42 is provided between the disk-like screw head 45 provided at the tip of the roller support shaft 42 and the upper surface of the rotation transmission roller 40. The rotation transmission roller 40 is urged by the disc spring 46 in the inner diameter direction of the lens barrel (downward in FIG. 1). Therefore, the taper roller surface 43 of the rotation transmission roller 40 is brought into contact with the annular taper surfaces 30 and 31 with a predetermined load by the biasing force of the disc spring 46. The roller support shaft 42 can be rotated by inserting a screwdriver or the like into the recess of the screw head 45, and by this rotation, the roller support shaft 42 moves back and forth in the axial direction, that is, in a direction orthogonal to the optical axis O. . When the roller support shaft 42 moves forward and backward in the same direction, the distance between the screw head 45 and the rotation transmission roller 40 changes, and the urging force applied to the rotation transmission roller 40 by the disc spring 46 sandwiched therebetween changes. Specifically, when the roller support shaft 42 is screwed in the inner diameter direction of the lens barrel, the contact pressure between the rotation transmission roller 40 and the annular tapered surfaces 30 and 31 increases, and the roller support shaft 42 is moved to the lens barrel. When pulled out in the outer diameter direction, the contact pressure becomes smaller.
[0014]
The operation of the full-time manual lens barrel configured as described above is as follows. In the manual focus in which the MF ring 20 is manually rotated, the rotational force of the MF ring 20 is transmitted to the rotation transmission roller 40 by the frictional force between the annular tapered surface 30 and the taper roller surface 43, and the rotation transmission roller 40. Tries to rotate (rotate) about the roller support shaft 42. Here, since the rotor 21b of the AF motor 21 is stopped, the rotational transmission roller 40 is circumferentially moved on the annular tapered surface 31 by the frictional force between the annular tapered surface 31 and the tapered roller surface 43 provided on the rotor 21b. To roll. The rotation of the rotation transmission roller 40 causes the cam ring 12 that supports the rotation transmission roller 40 to rotate in the circumferential direction around the optical axis O, and as a result, the focus lens group via the cam mechanism. FL moves in the optical axis direction.
[0015]
On the other hand, in the autofocus that rotates the rotor 21b of the AF motor 21, the rotational force of the rotor 21b is transmitted to the rotation transmission roller 40 by the frictional force between the annular tapered surface 31 and the tapered roller surface 43 of the rotor 21b. The rotation transmission roller 40 tries to rotate (spin) about the roller support shaft 42. Here, since the MF ring 20 is stopped, the rotation transmission roller 40 rolls on the annular tapered surface 30 in the circumferential direction by the frictional force between the annular tapered surface 30 and the tapered roller surface 43 of the MF ring 20. As the rotation transmission roller 40 rolls, the cam ring 12 rotates in the circumferential direction around the optical axis O, and as a result, the focus lens group FL moves in the optical axis direction via the cam mechanism.
[0016]
As described above, when one of the rotor 21b and the MF ring 20 of the AF motor 21 is rotated, only the cam ring 12 is rotated without rotating the other of the rotor 21b and the MF ring 20 without performing a special switching operation. Rotation is transmitted via the rotation transmission roller 40 so as to rotate. In order to perform such rotation transmission, it is necessary to apply a predetermined frictional force (contact pressure) between the taper roller surface 43 of the rotation transmission roller 40 and the pair of annular taper surfaces 30, 31. In the full-time manual lens barrel of this embodiment, this frictional force is obtained by a small disc spring 46 disposed between the rotation transmission roller 40 and the screw head 45. Therefore, the urging means and its installation space are small, which contributes to the miniaturization of the lens barrel.
[0017]
The reason why the urging means can be reduced in size according to this embodiment will be described in more detail. In the conventional full-time manual lens barrel described above, the rotation transmission surfaces of the MF ring and the AF ring are planes perpendicular to the optical axis. Therefore, in order to apply a contact pressure with the roller, it is attached in the optical axis direction. A biasing member is required, and in order to apply a biasing force in the optical axis direction, it was necessary to press either the MF ring or the AF ring. Each of the MF ring and the AF ring is a relatively large member centered on the optical axis, and if an equal pressing force is applied, the MF ring and the AF ring inevitably form a ring having the same diameter as the MF ring or AF ring. A biasing member is used. On the other hand, in the present embodiment, the rotation transmission surfaces of the MF ring 20 and the rotor 21b are annular tapered surfaces 30 and 31 including components inclined with respect to a plane orthogonal to the optical axis, and thus are relatively small members. By pressing the rotation transmission roller 40 in a direction orthogonal to the optical axis, a contact pressure can be applied between the annular tapered surfaces 30 and 31 and the rotation transmission roller 40. Therefore, the urging means provided in the rotation transmission mechanism is only a small disc spring 46 that presses the rotation transmission roller 40, and it is not necessary to provide the urging means in the front-rear direction of the MF ring 20 and the rotor 21b.
[0018]
In addition, the contact pressure between the annular tapered surfaces 30 and 31 provided by the disc spring 46 and the rotation transmission roller 40 can be easily changed simply by rotating the screw head 45 to advance or retract the roller support shaft 42 in the axial direction. Therefore, the adjustment work is not time-consuming.
[0019]
FIG. 2 shows a second embodiment of the present invention. The lens barrel in the figure is different from the first embodiment in that the AF drive source is an AF motor 50 in the camera body. The AF motor 50 rotates the gear shaft 52 via the reduction gear mechanism 51. The gear shaft 52 has a drive gear 53 at the tip, and the drive gear 53 meshes with an inner peripheral gear 55 formed on the inner peripheral surface of the AF ring 54. The AF ring 54 is supported on the outer peripheral surface of the fixed ring 11 ′ so as to be rotatable about the optical axis O, and is sandwiched between the outer flange portion 11 a ′ of the fixed ring 11 ′ and the rear retaining ring 26. Movement in the direction of the optical axis is restricted. An annular taper surface 56 similar to the previous annular taper surface 31 is formed at the front portion of the AF ring 54, and a rotation transmission roller with respect to the annular taper surface 56 and the annular taper surface 30 of the MF ring 20. 40 taper roller surfaces 43 are in contact with each other, and contact pressure is applied by a disc spring 46.
[0020]
Also in the embodiment of FIG. 2 described above, when one of the MF ring 20 and the AF ring 54 is rotated, the other of the MF ring 20 and the AF ring 54 is not rotated via the rotation transmission roller 40 and the cam ring 12 is rotated. Power is transmitted so as to rotate, and no special switching operation of the focus mode is required. And since the contact pressure of the rotation transmission roller 40 with respect to the annular taper surfaces 30 and 56 is provided by the small disk spring 46, size reduction of a lens barrel can be achieved. In particular, in the second embodiment, a fixing member such as the stator 21a of the AF motor 21 in the first embodiment is not provided in the lens barrel because the AF drive source is a motor in the camera body. It is difficult to provide conventional urging means for applying an urging force in the optical axis direction. However, the structure of the present invention in which the rotation transmission roller 40 is urged by the disc spring 46 can be provided without being limited to the aspect of the AF drive system, and thus has a wide application range.
[0021]
As mentioned above, although this invention was demonstrated based on illustration embodiment, this invention is not limited to embodiment. For example, the biasing means of the rotation transmission roller 40 in the embodiment is a disc spring 46, but different types of biasing means such as a coil spring and a spring washer can be used.
[0022]
Further, the inclination angle of the annular tapered surface (30, 31, 56) or the roller-side tapered surface (43) with respect to the optical axis O can be arbitrarily set. For example, the closer the angles of these contact surfaces are to be parallel to the optical axis O, the easier it is to receive a biasing force of a biasing member that presses the roller (the frictional engagement force increases). Therefore, the contact surface may be set to an appropriate angle in consideration of the urging force of the urging member, the rotational resistance acting on the MF ring and AF ring, and the like.
[0023]
【The invention's effect】
As is clear from the above, according to the present invention, it is possible to obtain a full-time manual lens barrel that has a simple structure, has high space efficiency, and can be configured regardless of the mode of AF driving.
[Brief description of the drawings]
FIG. 1 is an upper half sectional view showing a first embodiment of a full-time manual lens barrel to which the present invention is applied.
FIG. 2 is an upper half sectional view showing a second embodiment of a full-time manual lens barrel to which the present invention is applied.
[Explanation of symbols]
11 11 'Fixed ring 11a 11a' Outer flange portion 12 Cam ring 13 Lens frame 14 Cam pin 15 Straight guide groove 16 Cam groove 20 MF ring (manual focus operation ring)
21 AF motor 21a Stator 21b Rotor (AF drive ring)
23 front retaining ring 26 rear retaining ring 30 31 56 annular taper surface 40 rotation transmission roller 42 roller support shaft 43 taper roller surface 45 screw head 46 disc spring (biasing member)
50 AF motor 52 Gear shaft 53 Drive gear 54 AF ring 55 Inner peripheral gear FL Focus lens group O Optical axis

Claims (4)

A lens drive ring that moves the focus lens group in the optical axis direction by rotation about the optical axis;
An MF ring supported on the outer surface of the lens barrel and coaxial with the lens driving ring, and an AF ring rotated by an internal driving means;
A pair of annular tapered surfaces that are formed on the AF ring and the MF ring as part of a conical surface centered on the optical axis and are spaced apart from each other in the optical axis direction;
A roller support shaft protruding from the lens drive ring in the outer diameter direction perpendicular to the optical axis;
The roller support shaft is supported so as to be rotatable and movable along the roller support shaft, and forms a part of a conical surface centering on the roller support shaft. A rotation transmission roller having a tapered roller surface that is in contact, and whose movement in the direction along the roller support shaft is restricted by contact between the tapered roller surface and the pair of annular tapered surfaces;
A roller retaining portion provided at the tip of the roller support shaft;
An urging member that is inserted between the roller retaining portion and the rotation transmitting roller and urges the rotation transmitting roller in a contact direction with the pair of annular tapered surfaces; and the roller retaining portion and the rotation transmission. by changing the distance between the rollers to change the biasing force of the biasing member relative to the pivoting transfer roller, thereby adjusting the contact pressure of the tapered roller surface of the rotation conveying roller with respect to the ring-shaped tapered face of the AF ring and MF ring contact Pressure adjusting means;
With
When either one of the AF ring and the MF ring is rotated, the rotation transmission roller rolls on the other annular tapered surface of the AF ring and the MF ring to rotate the other AF ring or MF ring. A full-time manual lens barrel characterized by rotating a lens driving ring without moving it. 2. The full-time manual lens barrel according to claim 1, wherein the urging member comprises an annular spring provided around the roller support shaft between the roller retaining portion and the rotation transmission roller. Tube. 3. The full-time manual lens barrel according to claim 1, wherein the AF ring is a rotor of a vibration wave motor having an annular shape around the optical axis. 3. The full-time manual lens barrel according to claim 1, wherein the AF ring driving means is a built-in motor of a camera body to which the lens barrel can be attached and detached. .

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