JPH11231204A - Balancer of zoom lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately adjust a cycle with a differential motion between a zoom drive system and a balancer. SOLUTION: A variator lens group 1 and a compenstator lens group 2 are arranged so that they operate a prescribed movement via cam grooves 3a, 3b according to the rotation of cylindrical cam 3 coupled to a support shaft 4 fixedly supported at both ends via bearings 5. A balancer 6 is fitted to the support shaft 4 in the cylindrical cam so as to freely slide, and a locking member 7 provided in the balancer 6 slides in the straight groove 4a in the support shaft and it is thereby restricted for the balancer to rotate with respect to the support shaft 4. The cylindrical cam is provided with a bearing mounting base 8, and a bearing 9 fixed to this bearing mounting base 8 is engaged in a cam groove 6a arranged along the outer periphery of the balancer 6. When the position of the bearing mounting base 8 is changed in the circumferential direction of the cylindrical cam 3, the relative position between the cam of the lens drive system and the cam of the balancer drive system is changed, therefore, it become possible to minutely adjust the synchronization between the zoom drive system and the behavior of the balancer 6 by adjusting the position of the bearing mounting base 8 so that the behavior of the zooming operation may become satisfactory.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a balancer for a one-axis, two-operation zoom lens in a television camera.

[0002]

2. Description of the Related Art Conventionally, a broadcasting television camera uses a one-axis, two-operation zooming operation device in which zooming is performed by pushing and pulling an operation rod and focusing is performed by rotating the operation rod. In such a one-axis, two-operation zooming operation device, the operation force of the zoom drive system is affected by the lens weight due to the difference in posture, and thus the operation force is added to the operation force. Provided.

[0003]

The operation force required for the zooming operation is such that a zooming operation force with less unevenness is generated in the entire zoom range only when the operation force of the zoom drive system and the behavior of the balancer are accurately synchronized. In Although,
With the recent increase in magnification and performance of zoom lenses, there is a need for more strict synchronization between the zoom drive system and the behavior of the balancer.

However, in the conventional apparatus, the design of the balancer for canceling the increase in work due to the movement of the zoom lens accompanying the increase in the magnification of the zoom lens becomes very strict. Since an out-of-synchronization with the balancer's behavior adversely affects the zooming operation, an adjustment mechanism that can absorb these accumulated errors is desired.

An object of the present invention is to solve the above-mentioned problems,
It is an object of the present invention to provide a balancer for a zoom lens that can accurately adjust the synchronization between the zoom drive system and the behavior of the balancer.

[0006]

According to the present invention, there is provided a balancer for a zoom lens according to the present invention, comprising: a one-axis, two-operation zoom lens in which zoom control is operated by pushing and pulling an operation rod; And a mechanism for synchronizing the behavior of the balancer that cancels out with the zoom drive system.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the illustrated embodiment. FIG. 1 is a sectional view in the thrust direction of the first embodiment, FIG. 2 is a sectional view in the radial direction, and FIG. 3 is a plan view of a bearing mount for engaging with a cam groove of a balancer.
In a zoom lens having a structure in which a zoom drive system cam and a balancer drive system cam mutually move on the same axis, one end of a variator lens group 1 and a compensator lens group 2 is formed on a cylindrical cam 3 based on an optical relationship. The rotating members 1a and 2a which engage with the cam grooves 3a and 3b are attached. The other end of the lens group 1 and the lens group 2 is attached with a rotating member (not shown) that engages with a linear groove provided in the lens body. In accordance with the rotation of the cylindrical cam 3 connected to the bearing 4 via a bearing 5, a predetermined movement is performed via the cam grooves 3a and 3b.

On the other hand, a balancer 6 is slidably fitted on the support shaft 4 in the cylindrical cam 3, and a locking member 7 provided on the balancer 6 slides in a straight groove 4 a provided on the support shaft 4. The movement causes the rotation of the balancer 6 with respect to the support shaft 4 to be restricted. A bearing mount 8 is provided on the cylindrical cam 3, and a bearing 9 fixed to the bearing mount 8 is engaged in a cam groove 6 a provided along the outer periphery of the balancer 6. Accordingly, the cylindrical cam 3 rotates according to the movement of the lens frames 1 and 2, and the balancer 6 rotates the support shaft 4 in accordance with the rotation of the cylindrical cam 3.
Will perform a linear motion along.

The bearing mount 8 is provided with an elongated hole 8a corresponding to the adjustment range so as to be movable in the circumferential direction of the cylindrical cam 3. The position of the bearing mount 8 is adjusted in the circumferential direction of the cylindrical cam 3. Is changed, the relative position between the cam of the lens drive system and the cam of the balancer drive system changes. Therefore, by adjusting the position of the bearing mount 8 so that the behavior of the zooming operation is improved, the zoom drive system is improved. It is possible to fine-tune the synchronization between the balancer and the behavior of the balancer 6. After the bearing mount 8 is adjusted, it is fixed to the cylindrical cam 3 with a screw 10 for use.

FIG. 4 is a sectional view in the thrust direction of the second embodiment, and FIG. 5 is a sectional view in the radial direction. A cam groove for generating the movement of the balancer 6 in the thrust direction is formed not on the surface of the balancer 6 but inside the cylindrical cam 3.
Even with such a configuration, the zoom drive system and the balancer 6
It is possible to synchronize with the behavior of That is, the inner diameter portion 11 is fitted inside the cylindrical cam 3 provided with the cam grooves 3a and 3b based on an optical relationship such that the variator lens group 1 and the compensator lens group 2 move linearly. A balancer 6 is connected to a cam groove 11a provided in the inner diameter portion 11 via a bearing 12, whereby the balancer 6 slides in a straight groove 4a provided in the support shaft 4. ing. Cam groove 3 of cylindrical cam 3
After adjusting the relative positional relationship between the cam grooves 11a of the inner diameter portion 11a, 3b, the inner diameter portion 11 is fixed to the cylindrical cam 3 by a fixing screw 13 and used as an integral cylindrical cam.

Here, as the lens groups 1 and 2 move,
Since the cylindrical cam 3 and the inner diameter portion 11 change in the circumferential direction through the cam grooves 3a and 3b, the balancer 6 moves through the cam groove 11a provided in the inner diameter portion 11, so that the zoom drive system and the balancer 6 are moved. Can be fine-tuned to the synchronization with the behavior.

FIG. 6 is a sectional view in the thrust direction showing the structure of a zoom lens applied in the third embodiment, FIG. 7 is a sectional view in the radial direction at this time, and FIG. is there. Even when the support shaft 4 that supports the balancer 6 and the cylindrical cam 3 rotates without being fixed, it is possible to synchronize the behavior of the balancer 6 with the zoom drive system. That is, the support shaft 4 is configured to rotate in the circumferential direction.
Are connected to each other, and the support shaft fixing pin 21 is provided with an oval hole for the adjustment range.

By rotating the support shaft 4, the relative positions of the cam grooves 3a, 3b provided on the surface of the cylindrical cam 3 and the cam groove 6a of the balancer driving system change, so that the zooming operation can be performed well. Support shaft fixing pin 21
, It is possible to finely adjust the synchronization between the zoom drive system and the behavior of the balancer 6. And
After the support shaft fixing pin 21 is adjusted, the support shaft fixing pin 21 is used by being fixed with screws 22.

FIG. 9 is a sectional view in the thrust direction of the fourth embodiment, and FIG. 10 is a side view showing the positional relationship when the cylindrical cam of the zoom drive system and the cylindrical cam of the balancer drive system are connected by a belt. Is shown. In a zoom lens having a structure in which a zoom drive system cam and a balancer drive system cam move independently of each other, a variator lens group 1 and a compensator lens group 2 are formed in a cam groove formed on a cylindrical cam 31 based on an optical relationship. Rotating members 1a and 2a that engage with 31a and 31b are attached. The balancer 6 has a support shaft 4 having both ends fixedly supported independently of the cylindrical cam 31.
It is inserted in.

A drum 33 is connected to the periphery of the support shaft 4 via a bearing 32. A support member 34 fixed to the drum 33 is provided with a cam groove provided on the outer periphery of the balancer 6 in accordance with the rotation of the drum 33. The balancer 6 is made to perform a linear motion along the support shaft 4 by sliding in the inside 6a. The cylindrical cam 31 and the drum 33 are linked by a belt 36 connecting a gear 34 attached to the tip of the cylindrical cam 31 and a gear 35 attached to the tip of the drum 33.

In the fourth embodiment, the relative position between the lens driving system cam and the balancer driving system cam can be replaced by adjustment as a relative positional relationship between the gears 34, 35 connected by the belt 36. , The drum 3 of the gear 35
A long hole 35a corresponding to the adjustment range is formed in the attachment portion to the zoom gear 3, and the zoom drive system and the balancer are adjusted by rotating the gear 35 in the circumferential direction so as to improve the zooming operation. 6 can be fine-tuned for synchronization with the behavior.

FIG. 11 is an enlarged cross-sectional view of a rotating shaft of the fifth embodiment. In the zoom lens described in the fourth embodiment, as a mechanism for adjusting the deviation of synchronization between the zoom drive system and the behavior of the balancer 6 due to a processing error or an assembly error of the balancer 6, the support member 34 is provided in the radial direction of the balancer 6. A bearing shaft 41 provided with a screw so that it can be adjusted to a predetermined angle is attached.
Is assembled.

Due to the radial movement of the balancer 6 of the bearing shaft 41, the distance D from the rotation center axis R of the drum 33, which is the same as the center axis of the support shaft 4, to the position where the bearing 43 contacts the balancer 6 becomes variable. The work generated by the linear movement of the balancer 6 on the support shaft 4 is performed by a cam groove 6 a provided on the surface of the balancer 6 via a bearing 43 fixed to the drum 33 and engaged with the balancer 6. The rate of transmission as torque can be adjusted. With this adjustment, it is possible to absorb an error in the amount of work due to a processing error of the balancer 6.

FIG. 12 is an enlarged sectional view of the rotation shaft of the sixth embodiment. The adjustment of the contact diameter of the bearing 43 with the balancer 6 described in the fifth embodiment is a combination of the adjustment washer 45 and the bearing 43 assembled to the bearing shaft 44 with the holding screw 42.

As a result, the distance D from the rotation center axis R of the drum 33, which is the same as the center axis of the support shaft 4, to the position where the bearing 43 comes into contact with the balancer 6 becomes variable. Thus, the ratio of the rotational force transmitted to the drum 33 can be adjusted by the cam groove 6 a provided on the surface of the balancer 6. With this adjustment, it is possible to absorb an error in the amount of work due to a processing error of the balancer 6.

[0021]

As described above, the balancer of the zoom lens according to the present invention allows fine adjustment of the synchronization between the zoom drive system and the behavior of the balancer, which is most effective when adjusting the operability of the zooming operation. In addition, an error accumulated when assembling the balancer or the product can be absorbed by the adjustment mechanism, and the behavior of the balancer can be adjusted so that an optimum zooming operation can be performed.

[Brief description of the drawings]

FIG. 1 is a sectional view of a first embodiment in a thrust direction.

FIG. 2 is a sectional view in a radial direction.

FIG. 3 is a plan view of a bearing mount.

FIG. 4 is a sectional view in a thrust direction of a second embodiment.

FIG. 5 is a sectional view in a radial direction.

FIG. 6 is a sectional view of a third embodiment in a thrust direction.

FIG. 7 is a sectional view in the radial direction.

FIG. 8 is a configuration diagram of a support shaft fixing pin.

FIG. 9 is a sectional view in a thrust direction of a fourth embodiment.

FIG. 10 is a side view of the connected state of the gears.

FIG. 11 is a sectional view of a fifth embodiment.

FIG. 12 is a sectional view of a sixth embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Variator lens group 2 Compensator lens group 3, 31 Cylindrical cam 4 Support shaft 5, 7, 9, 14, 21, 22, 24, 31 Bearing 6 Balancer 8 Bearing mount 11 Inner diameter part 33 Drum 34, 35 Gear 36 Belt

Claims (6)

[Claims] 1. A one-axis, two-operation zoom lens in which zoom control is operated by pushing and pulling an operation rod, wherein a mechanism for synchronizing a behavior of a balancer for canceling an operation force generated by zooming with a zoom drive system is provided. Zoom lens balancer. 2. The balancer for a zoom lens according to claim 1, further comprising a mechanism for changing a relative positional relationship of the balancer drive system cam with respect to the zoom drive system cam. 3. The balancer for a zoom lens according to claim 2, wherein a member that slides in a cam groove of the balancer driving system rotates in a circumferential direction with respect to the cam groove to change a relative positional relationship. . 4. The balancer for a zoom lens according to claim 2, wherein the support member of the balancer drive system rotates in a circumferential direction with respect to the cam groove to change a relative positional relationship. 5. The balancer for a zoom lens according to claim 2, wherein a relative position relation is variable by rotating a connection portion of said balancer drive system to said zoom drive system cam. 6. A relative position relationship between a rotating member and said cam groove by changing a portion of said balancer drive system that slides in a cam groove in a radial direction with respect to said cam groove. 3. The balancer of the zoom lens according to 2.