JP4314516B2 - Lens device torque adjustment mechanism - Google Patents

Description

  The present invention relates to a torque adjustment mechanism of a lens apparatus, and more particularly to a torque adjustment mechanism that adjusts a rotational torque of a zoom ring of a lens apparatus.

  In a camera photographic lens device such as an ENG lens, the zoom lens is moved to adjust the focal length by rotating the cam cylinder with a zoom ring, as with other photographic lenses. Normally, the zoom ring is rotated by a motor of a drive unit that is detachably provided on the side of the fixed cylinder. However, during manual operation, a cameraman directly rotates the zoom ring to perform zoom adjustment.

  In such zoom adjustment at the time of manual operation, a mechanism provided with a torque adjustment mechanism for adjusting the rotational torque of the zoom ring has been conventionally known (for example, Patent Document 1), and a mechanism directly connected to the zoom ring. A torque adjusting mechanism 100 shown in FIG. 4 is known.

  The torque adjustment mechanism 100 includes a gear 104 that meshes with a gear portion of the zoom ring 102, a shaft body 106 inserted through the gear 104, a friction plate 108 through which the shaft body 106 is inserted, a shaft body 106 and a lens device. 110, a support frame 114 fixed to the fixed cylinder 112, a torque adjustment knob 116 screwed into the threaded portion 107 of the shaft body 106, and a spring 118 disposed between the torque adjustment knob 116 and the support frame 114. Etc.

  According to the torque adjusting mechanism 100, when the torque adjusting knob 116 is tightened, the spring 118 contracts, and the energizing force of the spring 118 (the energizing force in the direction indicated by the arrow A in FIG. 4) increases accordingly. ) Is transmitted from the torque adjustment knob 116 to the gear 104 through the shaft body 106. As a result, the gear 104 is pressed against the friction plate 108, so that the rotational resistance increases, and thus the rotational torque of the zoom ring 102 increases.

Contrary to this operation, when the torque adjusting knob 116 is loosened, the urging force of the spring 118 is lowered, and the rotational torque is reduced. When the distance between the support frame 114 and the torque adjustment knob 116 becomes longer than the free length of the spring 118, the urging force of the spring 118 becomes zero. It rotates without receiving resistance.
Japanese Patent Laid-Open No. 9-80292

  However, in the conventional torque adjustment mechanism 100 shown in FIG. 4, even when the torque adjustment knob 116 is loosened and the urging force of the spring 118 is reduced to zero, the frictional surface of the gear 104 and the friction plate 108 are caused by the adhesive force of the grease. May be maintained in close contact with each other. In this case, since the rotation resistance is applied from the gear 102 to the zoom ring, there is a drawback that the rotational torque of the zoom ring 102 cannot be reduced. The grease is supplied to a gap between the gear 104 of the rotating body and the shaft body 106 that is non-rotatably supported by the support frame 114 by the key 120 and the key groove 122. The above-described problems occur due to the exudate adhering to the friction surface of the gear 104 and the friction plate 108.

  The present invention has been made in view of such circumstances, and an object of the present invention is to propose a torque adjustment mechanism for a lens device capable of giving a desired rotational torque to a rotation ring of the lens device.

  In order to achieve the above object, the present invention provides a torque adjusting mechanism that is connected to a rotating ring of a lens device and adjusts the rotating torque of the rotating ring. The torque adjusting mechanism is connected to the rotating ring. A rotating member that is rotated together with the rotating ring, a friction plate that is relatively pressed against the rotating member, and a biasing force that relatively presses the friction plate and the rotating member. When the urging force applied by the first urging force applying means is less than or equal to a predetermined value, the urging force of the first urging force applying means is overcome, and the friction plate and the And a second urging force applying means for applying an urging force for relatively separating the rotating member to the friction plate or the rotating member.

  In order to achieve the above object, the present invention provides a torque adjustment mechanism that is connected to a rotation ring of a lens device and adjusts the rotation torque of the rotation ring. A gear meshed with the gear portion and rotated together with the rotating ring, a friction plate pressed relatively to the friction surface of the gear, and one end pivotally supported by the gear and fixed to the lens device A shaft body inserted into the support frame and the friction plate, a torque adjustment member screwed into a screw portion formed at the other end of the shaft body, and the torque adjustment member and the support frame. An urging force in a direction of clamping the friction plate between the gear and the support frame is rotated via the shaft body by rotating the torque adjusting member in a direction approaching the support frame. A first biasing member applied to the gear; and the shaft When the urging force by the first urging member becomes less than or equal to a predetermined value by rotating the torque adjusting member in a direction away from the support frame. A second urging member that overcomes the urging force and applies an urging force in a direction opposite to the urging force to the gear via the shaft body.

  According to the present invention, when the urging force by the first urging force applying means is increased, the frictional resistance between the friction plate and the rotating member increases, so that the rotational torque of the rotating ring gradually increases, When the urging force by the first urging force applying means is reduced, the frictional resistance between the friction plate and the rotating member is reduced, and the rotational torque of the rotating ring is gradually reduced. When the urging force by the first urging force applying means becomes below a predetermined value, the urging force of the second urging force applying means overcomes the urging force of the first urging force applying means. The friction plate and the rotating member are relatively separated by the biasing force of the means. Thereby, when the urging force by the first urging force applying means is reduced, it is possible to prevent the friction plate and the rotating member from coming into close contact with each other, so that a desired rotational torque can be applied to the rotating ring.

  Further, according to the present invention, when the torque adjusting member is rotated in the direction approaching the support frame, the biasing force in the direction of clamping the friction plate between the gear and the support frame is applied from the first biasing member. Since it is given to the gear through the shaft body, the frictional resistance between the friction plate and the rotating member increases, and the rotational torque of the rotating ring gradually increases. Further, when the torque adjusting member is rotated in a direction away from the support frame, the urging force by the first urging member is weakened, so that the frictional resistance between the friction plate and the rotating member is reduced, and the rotation ring The rotational torque gradually decreases. When the urging force by the first urging member becomes a predetermined value or less, the urging force of the second urging member overcomes the urging force of the first urging member. Is applied to the gear through the shaft, and the gear is separated from the friction plate. Thereby, when the urging | biasing force by a 1st urging | biasing member becomes small, since contact | adherence with a friction plate and a gear can be prevented, a desired rotational torque can be given to a rotation ring.

  The rotating ring is a zoom ring that moves a zoom lens of the lens device. Thereby, the operational feeling of the zoom ring can be finely adjusted.

  According to the torque adjustment mechanism of the lens device according to the present invention, the first urging force applying means, and the second urging force applying means for generating an urging force smaller than the urging force by the first urging force applying means, And adjusting the rotational torque of the rotating ring by the first urging force applying means, and when the urging force of the first urging force applying means becomes a predetermined value or less, the urging force of the second urging force applying means Thus, the friction plate and the rotating member are forcibly separated from each other to prevent the friction plate and the rotating member from being in close contact with each other, so that a desired rotational torque can be applied to the rotating ring.

  Hereinafter, preferred embodiments of a torque adjustment mechanism of a lens apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  A focus ring 14, a zoom ring (rotation ring) 16, and an iris ring 18 are rotatably provided on the fixed cylinder 12 of the lens apparatus 10 shown in FIG. The lens configuration of the lens device 10 includes a focus lens group 20, moving zoom lens groups 22 and 24, a relay lens group 26, and a master lens group 28, and includes a moving zoom lens group 24 and a relay lens group 26. An iris device 30 is disposed between them.

  The focus lens group 20 is supported by a focus lens barrel 32 formed integrally with the focus ring 14, and the focus lens barrel 32 is supported by the fixed cylinder 12 so as to be movable in the front-rear direction of the optical axis P via a helicoid screw. ing. Therefore, when the focus ring 14 (which may be the focus lens barrel 32) is rotated, the focus lens group 20 is driven in the front-rear direction of the optical axis P, and focus adjustment is performed.

  On the other hand, a zoom cam cylinder 34 is rotatably disposed in the fixed cylinder 12, and the zoom cam cylinder 34 is connected to the zoom ring 16 via a connection pin 36. Therefore, when the zoom ring 16 is rotated, the zoom cam cylinder 34 is also rotated integrally with the zoom ring 16.

  Cam grooves 38 and 40 are formed in the zoom cam cylinder 34. A cam pin 44 protruding from the lens support frame 42 of the moving zoom lens group 22 is fitted into the cam groove 38. Further, a cam pin 48 protruding from the lens support frame 46 of the moving zoom lens group 24 is fitted into the cam groove 40. Further, the cam pins 44 and 48 are fitted into a rectilinear groove 50 formed on the inner peripheral surface of the fixed cylinder 12 through the cam grooves 38 and 40. Therefore, when the zoom cam cylinder 34 is rotated by the zoom ring 16, the movable zoom lens groups 22 and 24 are moved back and forth along the straight groove 50 while being restricted by the cam grooves 38 and 40, and zoom adjustment is performed.

  By the way, the zoom ring 16 of the lens device 10 is provided with a torque adjustment mechanism 50 that adjusts the rotational torque of the zoom ring 16.

  As shown in FIG. 2, the torque adjusting mechanism 50 includes a gear (rotating member) 52, a friction plate 54, a support frame 56, a shaft body 58, a torque adjusting knob (torque adjusting member) 60, a spring (first member). An urging force applying means: a first urging member 62 and a spring (second urging force applying means: a second urging member) 64 are included.

  The gear 52 is engaged with the gear portion of the zoom ring 16 and supported by the shaft body 58 via a bearing 66 so as to be rotated together with the zoom ring 16. The friction plate 54 is a member that is pressed against the friction surface 53 of the gear 52 to give rotation resistance to the zoom ring 16. The friction plate 54 is formed in a ring shape on the side surface on the gear side of the support frame 56 that is formed in a cylindrical shape. It is fixed.

  The shaft body 58 has a bearing 66 attached to a small-diameter shaft portion 68 formed at the left end portion in FIG. 2, and the support frame 56 and the friction plate 54 are inserted and disposed. The support frame 56 is fixed to the fixed cylinder 12 by screws 70, and the shaft body 58 is connected to the fixed support frame 56 by a key 72 and a key groove 74, whereby the shaft body 58 is fixed to the support frame 56. It is supported so that it cannot rotate.

  A threaded portion 76 is formed at the right end of the shaft body 58 in FIG. 2, and the female threaded portion 61 of the torque adjusting knob 60 is screwed to the threaded portion 76.

  Further, the spring 62 is disposed between the torque adjustment knob 60 and the support frame 56, and is rotated by contracting the torque adjustment knob 60 in a direction approaching the support frame 56 as shown in FIG. The biasing force in the direction in which the friction plate 54 is clamped between the support frame 56 and the support frame 56 (direction indicated by the arrow A) can be applied to the gear 52 via the shaft body 58.

  On the other hand, the spring 64 is disposed in a recess 78 formed in the shaft body 58, and the left end 64 </ b> A is in contact with the left side surface of the recess 78 in FIG. 2, and the right end 64 </ b> B is embedded in the support frame 56. It is in contact with the pin 80. Accordingly, the spring 64 is disposed between the shaft body 58 and the support frame 56. Further, the spring 64 rotates the torque adjusting knob 60 in the direction away from the support frame 56 as shown in FIG. 3 and overcomes the biasing force when the biasing force of the spring 62 becomes a predetermined value or less. An urging force in the opposite direction (direction indicated by arrow B) can be applied to the gear 52 via the shaft body 58. That is, the spring 64 having a smaller spring constant than the spring 62 is used.

  Next, the operation of the torque adjustment mechanism 50 configured as described above will be described.

  First, when the torque adjustment knob 60 is rotated in the direction approaching the support frame 56 as shown in FIG. 2, the urging force in the direction in which the friction plate 54 is clamped between the gear 52 and the support frame 56 (direction indicated by arrow A). However, since this is applied from the spring 62 to the gear 52 via the shaft body 58, the frictional resistance between the friction plate 54 and the friction surface 53 of the gear 52 increases, and the rotational torque of the zoom ring 16 gradually increases.

  When the torque adjusting knob 60 is rotated away from the support frame 56 as shown in FIG. 3, the urging force of the spring 62 is weakened, so that the frictional resistance between the friction plate 54 and the friction surface 53 of the gear 52 is small. Thus, the rotational torque of the zoom ring 16 gradually decreases.

  When the urging force of the spring 62 becomes a predetermined value or less, the urging force of the spring 64 overcomes the urging force of the spring 62. As a result, the biasing force of the spring 64 in the direction indicated by the arrow B is applied to the gear 52 via the shaft body 58, so that the gear 52 is forcibly separated from the friction plate 54.

  Therefore, according to the torque adjustment mechanism 50 of the embodiment, the spring 62 and the spring 64 that generates an urging force smaller than the urging force of the spring 62 are provided, and the rotational torque of the zoom ring 16 is adjusted by the spring 62. When the urging force of the spring 62 becomes a predetermined value or less, the urging force of the spring 64 forcibly separates the friction plate 54 and the gear 52, thereby preventing the grease contact between the friction plate 54 and the gear 52. A desired rotational torque can be applied to the zoom ring 16.

Half sectional view of a photographic lens device for a camera to which a torque adjustment mechanism of an embodiment is applied Enlarged sectional view of the torque adjustment mechanism shown in FIG. Enlarged sectional view of the torque adjustment mechanism shown in FIG. Structure of conventional torque adjustment mechanism

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Lens apparatus, 12 ... Fixed cylinder, 14 ... Focus ring, 16 ... Zoom ring (rotation ring), 34 ... Zoom cam cylinder, 50 ... Torque adjustment mechanism, 52 ... Gear (rotation member), 54 ... Friction plate, 56 ... support frame, 58 ... shaft body, 60 ... torque adjusting knob (torque adjusting member), 62 ... spring (first urging force applying means: first urging member), 64 ... spring (second urging member) (Biasing force applying means: second biasing member)

Claims (3)

In a torque adjustment mechanism that is connected to the rotation ring of the lens device and adjusts the rotation torque of the rotation ring,
The torque adjustment mechanism is
A rotating member connected to the rotating ring and rotated together with the rotating ring;
A friction plate pressed against the rotating member;
First urging force applying means for applying an urging force for relatively pressing the friction plate and the rotating member to the friction plate or the rotating member;
When the urging force by the first urging force applying means is below a predetermined value, the urging force of the first urging force applying means is overcome and the urging force that relatively separates the friction plate and the rotating member is applied to the friction plate. Or a second urging force applying means applied to the rotating member;
A torque adjustment mechanism for a lens apparatus, comprising: In a torque adjustment mechanism that is connected to the rotation ring of the lens device and adjusts the rotation torque of the rotation ring,
The torque adjustment mechanism is
A gear meshed with the gear portion of the rotating ring and rotated together with the rotating ring;
A friction plate pressed against the friction surface of the gear;
One end of the gear is pivotally supported, and a shaft inserted into a support frame fixed to the lens device and the friction plate,
A torque adjusting member screwed into a threaded portion formed at the other end of the shaft;
A direction that is arranged between the torque adjusting member and the support frame, and clamps the friction plate between the gear and the support frame by rotating the torque adjusting member in a direction approaching the support frame. A first urging member that gives the urging force to the gear through the shaft body;
When the urging force by the first urging member is less than or equal to a predetermined value by rotating the torque adjusting member in a direction away from the support frame, which is disposed between the shaft body and the support frame. A second biasing member that overcomes the biasing force and applies a biasing force in a direction opposite to the biasing force to the gear through the shaft body;
A torque adjustment mechanism for a lens apparatus, comprising:   The torque adjusting mechanism for a lens device according to claim 1, wherein the rotating ring is a zoom ring that moves a zoom lens of the lens device.

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