JPS59810B2 - Zoom lens moving device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a zoom lens, in particular, a means for canceling the acting force on each movable optical system for zooming that is caused by changes in elevation and elevation during use. The present invention relates to a zoom lens moving device such as the one described above.

Modern zoom lenses have significantly increased their variable power ratios, and as a result, the movable optical systems for zooming have become significantly larger. Despite the increased size of the system, smooth operation during zooming is strictly required.

However, with such a zoom lens with a high zoom ratio, each movable optical system for zooming has become larger and heavier, making it difficult to use the zoom lens when tilting it. Due to changes in posture, the acting force exerted on the zooming operation ring (or optical system, drive ring) from each movable optical system itself becomes very significant, and the acting force due to each optical system itself becomes very significant. However, this varies greatly depending on the degree of change in the posture of the zoom lens during use, that is, the tilt angle during use, and the position of each movable optical system on the optical axis. This results in large fluctuations in the required drive torque, and therefore it is not possible to smoothly perform zooming operations.

In order to eliminate such inconveniences, conventionally, a cam cylinder having a cam groove for zooming (which regulates the movement of each movable optical system in a predetermined relationship for zooming) is further equipped with a second cam groove. A completely separate cam cylinder is provided, and this second cam cylinder is equipped with a balancer or counter weight for canceling out the acting force related to each movable optical system caused by the change in the attitude of the zoom lens. (weight)
In addition to forming a cam groove for regulating the position of the means (hereinafter referred to as a balancer) in the direction along the optical axis,
This second cam cylinder is drivenly connected to the cam cylinder having the cam groove for zooming, and during zooming,
There is a zoom lens in which the forces exerted by the above-mentioned optical systems are eliminated by operating this second cam cylinder together with the above-mentioned zooming cam cylinder. However, for a zoom lens with such a configuration, (1)
The cam cylinder of the above-mentioned balancer, which regulates the means for canceling the acting force of each movable optical system, is driven and connected to a completely separate cam cylinder for zooming. (2) Since two separate cam cylinders are provided, zooming and
The structure of the lens mechanism becomes more complex, and the zoom lens itself becomes larger. (3) When driving each movable optical system using a drive source such as a motor, the load on this drive source increases. Therefore, a relatively high-output drive source is required. (4) Since a second cam cylinder is required in addition to the zooming cam cylinder, its processing and assembly must be considered. However, there are disadvantages such as an increase in the cost of the zoom lens as a whole.

The present invention eliminates all of these drawbacks in conventional zoom ranges, and operates the means for canceling the force exerted by the movable zooming optical system of the balancer in an extremely rational manner. The main feature of this system is that it has a means (balancer) for canceling out the force exerted by each movable optical system due to changes in the attitude of the zoom lens. , counter weight, etc.) is provided in the cylindrical member that drives the driving optical system during zooming.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, but prior to this, a description will first be added of the zoom lens of Jubei mentioned above with reference to the drawings.

FIG. 1 is a partially cutaway perspective view showing the structure of the above-mentioned conventional zoom lens, particularly the main parts related to the present invention. First, the structure will be explained. 1 is a fixed cylindrical member; The fixed cylinder 1 has a movable optical system for zooming, that is,
Regulating grooves 1a and 1b are formed to restrict the movement of the variable power optical system V and the correction optical system C in the direction along the optical axis.

Reference numeral 2 denotes a cylindrical member for driving an optical system that is rotatably fitted loosely around the outer periphery of the fixed cylinder 1, and the driving cylinder 2 has a predetermined member for controlling the movement of each of the optical systems V and C mentioned above for zooming. So-called cam grooves 2a and 2b for zooming are formed to regulate the position in a certain relationship.

3 is a holding lens barrel that movably holds the variable magnification optical system V;
A pin 4 implanted in a part of the outer circumference of the fixed cylinder 1
After passing through the regulation groove 1a, the cam groove 2a of the drive cylinder 2 is fitted into the cam groove 2a.

5 is a holding lens barrel that movably holds the correction optical system C;
The pin 6 implanted in a part of the outer circumference passes through the regulation groove 1b of the fixed cylinder 1 and then fits into the cam groove 2b of the drive cylinder 2.

Therefore, with the above configuration, when the drive cylinder 2 is rotated relative to the fixed cylinder 1, the levers 4 and 6 connected to the optical system holding barrels 3 and 5 move into the cam grooves 2a and 2 of the drive cylinder 2. 2
At the same time, its movement is controlled by the fixed cylinder 1.
are regulated in the direction along the optical axis by the regulating grooves 1a and 1b, and as a result, the variable power optical system V and the correction optical system C are moved under a predetermined relationship for zooming, and This results in a zooming effect.

By the way, when the zoom lens configured as described above is used in an inclined position from a horizontal position, an acting force is applied from the optical systems V and C to the driving cylinder 2 via the pins 4 and 6. The forces exerted by the optical systems V and C are the respective weights of the optical systems V and C and the difference between them, the inclination angle of the zoom lens, and the cam grooves 2a and 2 in the fitting portions of the pins 4 and 6. 2
The effect varies depending on the rising angle of b, etc., but it becomes especially noticeable when the optical systems V and C become heavier, and the acting force of the optical systems V and C increases the power of 1 driving cylinder 2.
The required driving torque of the zoom lens fluctuates greatly, making it impossible to smoothly perform zooming operations. And in extreme cases,
Due to the acting force of this optical system, the drive cylinder 2 is rotated without permission, and the variable power ratio during zooming changes, which may lead to an unexpected failure during photographing. In order to eliminate such inconveniences, conventional solutions have been adopted as described below.

That is, in FIG. 1, 8 is a weight means such as a counter weight provided for the purpose of effectively canceling out the acting force due to the movable optical systems V and C as explained above. The weight 8 is allowed to slide only in the direction along the optical axis of the zoom lens by the support rod 10 (that is, rotation relative to the rod 10 is restricted).
Supported.

Reference numeral 11 denotes a cylindrical member that drives the counter weight 8 during zooming operation of the zoom lens, and the driving cylinder 11 includes a cam groove 1 for regulating the position of the counter weight 8 on the rod 10 during zooming.
1a, and the implanted hem 9 of the counter weight 8 is fitted into the cam groove 11a.

Reference numeral 12 denotes a gear attached to the outer periphery of the counter weight driving cylinder 11, and the gear 12 meshes with the gear 7 attached to the outer periphery of the optical system driving cylinder 2 mentioned above.

The cam groove 11a of the counter weight drive cylinder 11 allows the above-mentioned acting force from each movable optical system V and C, which changes as appropriate during zooming, to be transferred to the counter weight drive cylinder 11.
The weights 8 can be designed so that they can be effectively canceled at each point in the entire zooming range.

Therefore, when the optical system driving cylinder 2 is rotated to perform zooming, each optical system V and C is driven as described above to obtain a zooming effect, and at this time, the gear 7
and 12, the counter weight driving cylinder 11 is rotated, and the counter weight 8 is rotated through the cam groove 11.
The position of the support rod 10 changes while being regulated by a,
At each zooming point, the above-mentioned forces exerted by the optical systems V and C are effectively canceled out.

However, the zoom lens with the configuration as explained above,
For lenses, as mentioned above, that is, (1) to
There are drawbacks such as (4).

Next, an embodiment of the present invention aimed at improving the conventional zoom lens as described above will be described.
) Figures 2 to 4 show a first embodiment of the present invention in which the above-mentioned cam groove for regulating the counterweight is replaced with a cam groove for zooming, that is, the movement of the movable optical system for zooming is used for zooming. This figure shows a case in which the optical system is installed in an optical system drive cylinder having a curved cam groove that regulates in a predetermined relationship. Figure 2 is an external perspective view of the main part, and Figure 3 is a FIG. 4 is a developed view of the optical system and driving cylinder, and is a sectional view showing details of the internal structure of the zoom lens.

First, to explain its structure, in FIGS. 2 to 4, 21 is a cylindrical member fixed to a fixed main lens barrel 27 (see FIG. 4) with a screw 28. 21 includes a linear regulating groove 21a for regulating the movement of the variable magnification optical system V and the correction optical system C in a direction substantially along the optical axis.
and 21b are formed.

Reference numeral 22 denotes a cylindrical member for driving an optical system rotatably fitted loosely around the outer periphery of the fixed cylinder 21. On the inner periphery of the driving cylinder 22, a movable optical system V and a correction optical system C are provided. So-called cam grooves 22a and 22b for zooming, which regulate the cam grooves 22a and 22b in a predetermined relationship for zooming, are provided without reaching the outer periphery, that is, without penetrating the cam grooves 22a and 22b. , a counter is provided on the outer periphery of the driving cylinder 22 to cancel the acting force due to the optical systems V and C.
Cam grooves 22c and 22d that regulate the positions of weight means 29 and 32 such as weights on support rods 31 and 34 are provided without reaching the inner periphery thereof (see Fig. 3). .

Reference numeral 23 denotes a holding lens barrel that movably holds the variable magnification optical system V, and two roller members 35 and 36 are pivotally attached to a pin 24 provided on a part of its outer periphery. The rollers 35 and 36 are located in the regulation groove 21a of the fixed cylinder 21, respectively.
and is loosely fitted into the cam groove 22a of the drive cylinder 22.

Reference numeral 25 denotes a holding lens barrel that movably holds the correction optical system C. Two roller members 37 and 38 are pivotally attached to a pin 26 implanted in a part of the outer periphery of the holding lens barrel. 37 and 38 are the regulation grooves 21b of the fixed cylinder 21, respectively.
and is loosely fitted into the cam groove 22b of the drive cylinder 22.

The counter weights 29 and 32 are slidably supported by support rods 31 and 34 that are fixed to support members 39 and 41 provided on the main lens barrel 27, respectively. The counter weights 29 and 32
The pins 30 and 33 implanted in the main lens barrel 27 pass through long grooves 27a and 27b formed in the main lens barrel 27 to restrict the rotation of the counterweights 29 and 32 relative to the rods 31 and 34, respectively. .

Roller members 40 and 42 are pivotally attached to the tips of the pins 30 and 33, respectively. It is loosely fitted into the cam grooves 22c and 22d. In addition, during the above explanation, the second counter
Support member 41 and roller member 4 related to weight 32
2 and the long groove 27b of the main lens barrel 27 are not clearly shown in the figure, but these are the support member 39 related to the first counter weight 29, the roller member 40, and the long groove 27a of the main lens barrel 27. Therefore, in the figure, those related to the first counter weight 29 are clearly shown, and those related to the second counter weight 32 are shown.
In particular, in FIG. 4, the symbols indicating each element are shown in parentheses in correspondence with the first counter weight 29.

In FIG. 4, F is a focusing optical system, R is a relay optical system, and the relay optical system R is held by a holding lens barrel 43, and the holding lens barrel 43 is attached to a screw 44. Therefore, it is fixed to a fixed lens barrel 44.

Next, the operation of the zoom lens configured as described above during zooming operation will be described.

In order to perform zooming, when the driving cylinder 22 is rotated relative to the fixed cylinder 21 through a known means not shown here, a cam groove 22a for zooming formed on the inner circumference of the driving cylinder 22 is rotated. and 22b, pins 24,2
6 and rollers 36 and 38, the variable power optical system V and the correction optical system C are connected to each other through the regulating groove 2 of the fixed cylinder 21.
1a and 21b, the moving direction is regulated to substantially the direction along the optical axis, and the cam grooves 22a and 22b drive the cam grooves 22a and 22b in a predetermined relationship for zooming. is obtained.

On the other hand, at this time, cam grooves 22c and 22d for regulating the counter weight formed on the outer periphery of the first driving cylinder 22.
The first and second counter weights 29 and 32, which are connected via pins 30 and 33 and rollers 40 and 42, respectively, move into the cam groove 22c when the drive cylinder 22 rotates. and 22d, the positions on the support rods 31 and 34 are successively changed, and the rods are driven in a predetermined relationship so as to satisfactorily cancel out the above-mentioned forces exerted by the optical systems V and C at each zooming point. Ru.

Therefore, the action of the counter weights 29 and 32 effectively cancels out the forces exerted by the movable optical systems V and C over the entire zooming range, making the zooming operation extremely smooth. Here, the cam groove 22a for zooming in the drive cylinder 22 is
and 22b and the counterweights 22c and 22d will be explained with particular reference to FIG. First, the first counterweight 29 is for canceling the acting force exerted by the variable magnification optical system V. Therefore, the cam groove 2 that controls the first counterweight 29
The shape of the cam groove 2c for controlling the variable magnification optical system V is designed in a certain correlation with the cam groove 22a.

In this case, the shape of the cam groove 22e, that is, the rising angle of each part of the cam groove from the horizontal line, is largely determined by the relationship between the weight of the counter weight 29 and the weight of the variable power optical system. It is. That is, here and now, when the zoom lens is tilted at a predetermined angle from the horizontal position, the force exerted from the counter weight 29 on the drive cylinder 22 via the roller 40 is transferred from the variable magnification optical system V to the roller at this time. Assuming that the weight of the counterweight 29 is selected so as to be the same as the force exerted on the drive cylinder 22 via the cam groove 22c, the direction of the force acting on the counterweight 29 is Variable power optical system V
It is sufficient to design the shape so that it is completely opposite to the direction of the acting force (that is, without changing the magnitude of the force).

This means that in the developed view of the drive cylinder 22 in FIG. 3, the cam groove 22c should be designed so that it is line symmetrical with respect to the cam groove 22a. It is something. Therefore, when actually designing the cam groove 22c, a cam groove that is line-symmetrical with respect to the cam groove 22a is used as a basis, and the design is made according to the weight relationship between the optical systems V and C and the counter weight 29. The shape of the cam groove, that is, the rising angle of each part of the cam groove from the horizontal line is determined.

Note that the second counter weight 32 is a correction optical system C.
This is to cancel out the acting force due to
The cam groove 22d for controlling the counterweight 32 can be considered in the same way as the cam groove 22b for controlling the correction optical system C.

Next, referring to FIGS. 5 to 7, as a second embodiment, the above-mentioned cam groove for regulating the counter weight is arranged so that the movement of the movable optical system for zooming is substantially aligned with the optical axis during zooming. A case will be described in which the optical system drive cylinder is provided with a linear regulating groove for regulating the optical system in the longitudinal direction.

FIG. 5 is an external perspective view of the main parts of the zoom lens in the second embodiment, FIG. 6 is a developed view of the optical system driving cylinder, and FIG. 7 is an internal view of the zoom lens. FIG. 3 is a cross-sectional view showing details of the structure.

First, to explain its configuration, the second embodiment shown in FIGS. 5 to 7 differs from the first embodiment shown in FIGS. 2 to 4 in that the optical system drive is The only difference is the configuration of the cam groove between the cylinder and the fixed cylinder, and the configuration of other parts is completely the same as in the first embodiment, so there are no overlapping components with the first embodiment. The same reference numerals as above will be used for these, and the explanation thereof will be omitted to the extent that it does not impede the understanding of this example.

In FIGS. 5 to 7, 2" indicates the fixed primary lens barrel 27 (
(see Fig. 7), the fixed cylinder 2'
The above-mentioned curved cam grooves 2'a and 2V for zooming are used to regulate the movement of the variable magnification optical system and the correction optical system C in a predetermined relationship for zooming.
b is formed.

Reference numeral 22' denotes a driving cylinder for the optical system 5 which is rotatably fitted loosely around the outer periphery of the fixed cylinder 2'', and a driving cylinder for the optical system 5 is fitted on the inner periphery of the 1 driving cylinder 22'' to substantially control the movement of the above-mentioned movable optical system and C. Regulation grooves 22'a and 22'b for regulating the direction along the optical axis are provided without reaching the outer periphery, and on the other hand, the aforementioned counter grooves 22'a and 22'b are provided on the outer periphery. Cam grooves 27c and 22 for regulating weights 29 and 32
'd is formed without reaching its inner periphery (see FIG. 6).

Two rollers 35 and 36, which are pivotally attached to the implant pin 24 of the holding lens barrel 23 that holds the variable magnification optical system, are connected to the cam groove 2Va of the fixed cylinder 2'' and the regulation groove 22 of the drive cylinder 22', respectively. The two rollers 37 and 38, which are loosely fitted into the fixed cylinder 2'a and pivotally attached to the implant pin 26 of the holding lens barrel 25 that holds the correction optical system C, respectively Groove 2
Yb and the regulating groove 22'b of the drive cylinder 27 are loosely fitted. Also, the planting pins 3 of the counter weights 29 and 32
Rollers 40 and 42 which are pivotally mounted to 0 and 33 are
They are loosely fitted into counterweight regulating cam grooves 22''C and 22''d of the drive cylinder 22'', respectively.

Other components not mentioned here are completely the same as in the first embodiment.

Next, the operation of the zoom lens having the following configuration during zooming operation will be described.

When the first driving cylinder 227 is rotated relative to the fixed cylinder 211 in order to perform zooming, the pins 24, 26 are inserted into the regulating grooves 22''a and 22'b formed on the inner circumference of the driving cylinder 22''. The variable magnification optical system V and the correction optical system C, which are connected via the rollers 36 and 38, are connected to the fixed cylinder 21.
While being regulated in a predetermined relationship for zooming by the zooming cam grooves 2'a and 2Vb, the cam grooves 221a and 22''b allow the cam grooves 2'a and 2Vb to substantially move in the direction along the optical axis. Therefore, a zooming effect is obtained as described above.

On the other hand, at this time, cam grooves 22'c and 22 for regulating the counter weight formed on the outer periphery of the driving cylinder 221
``d, pins 30, 33 and rollers 40, 42, respectively.
As described above, the first and second counter weights 29 and 32, which are connected via the cam grooves 2Tc and 22''d, respectively
As a result, the positions on the support rods 31 and 34 change successively and are driven in a predetermined relationship so as to satisfactorily cancel out the above-mentioned forces exerted by the optical systems V and C at each zooming point. Therefore, as in the first embodiment, the forces exerted by the movable optical systems v and C can be effectively canceled over the entire zooming range by the action of the counter weights 29 and 32. This makes zooming operations extremely smooth.

In addition, in this second embodiment, unlike the first embodiment, the cam groove 22' for regulating the counter weight is
c and 22'd, and zooming cam grooves 2'a and 2'd.
``b'' are formed in completely separate cylindrical members 22'' and 2'', respectively, but the cam groove 2'' for zooming is
The relationship between the counterweight regulating cam grooves 27c and 22'd with respect to the counterweight regulating cam grooves 27c and 22'd is almost the same as in the first embodiment. 22 and 22'd, it can almost be considered that the first embodiment has been described.In the two embodiments described above,
The acting force due to the variable magnification optical system V and the acting force due to the correcting optical system C are assumed separately, and these are each canceled by separate counter weights, but as a practical matter, the above The forces exerted by both optical systems and C act as a resultant of the individual forces of each optical system V and C, and therefore, in practice, only one counterweight It becomes possible to cancel the acting forces due to systems V and C.

Next, this will be explained. Based on the above idea, Fig. 8 shows a developed view of the optical system drive cylinder in the case where only one counter weight is used to cancel out the acting force due to optical systems V and C. , which shows a case that can be applied to the first embodiment described above.

Therefore, the explanation will be made here in comparison with the developed view of the driving cylinder shown in FIG. As mentioned above, in the first embodiment, the first and second counter weights 29 and 3 are provided corresponding to the variable magnification optical system V and the correction optical system C, respectively.
Therefore, the drive cylinder 22 has a first counter weight control cam groove 22c corresponding to the cam groove 22a for controlling the variable magnification optical system, and a first counter weight control cam groove 22c for controlling the correction optical system. A second counter corresponds to the control cam groove 22b.
Each cam groove 22d for weight control was provided (see Figure 3), but these can be combined into one cam groove, and this combined cam groove is the eighth cam groove. It is shown at 22e in the figure.

Based on the same considerations as in the first embodiment described above, this synthetic cam groove 22e is the same as the cam groove 22 for controlling the variable magnification optical system.
Based on a cam groove that is axisymmetric with respect to the synthetic cam groove of a and the cam groove 22b for controlling the correction optical system, depending on the weight relationship between the counter weight to be used and the optical system V and C. , its shape, that is, the rising angle of each part of the cam groove is determined.

Note that although the composite cam groove for the drive cylinder 22'' in the second embodiment is not particularly shown in the drawings, the above-mentioned concept can of course be applied to this as well. It is about.

Finally, for reference, a basic theoretical formula for designing the shape of the synthetic cam groove 22e, which is obtained through mechanical analysis, will be listed below.

As shown in FIG. 9, when the driving cylinder 22 is in an upright state (the central axis of the cylinder 22 at this time is the y-axis), γ
...Radius T of the driving cylinder 22...
...Driving torque W1 applied to the drive cylinder 22 during zooming operation... Weight W2 of the variable magnification optical system V
゜゜゜゛゜゜゜゜゜Weight W3 of correction optical system C...
...Counter weight weight θbi...
...Rise angle θ2 of cam groove 22a from the X axis...
... Rising angle θ of the cam groove 22b from the X axis
3...Cam groove 22ef) Assuming the rising angle from the x-axis, each cam groove 22a, 22b and 22e
If we ignore the friction between the rollers and the above-mentioned rollers that are loosely fitted therein, the free force of this system is X. Component X in the y direction.
Y becomes.

Here, from the principle of virtual work, component) Therefore, it follows from equations (1), (2), and (3).

Here, the constraint conditions for optical systems V and C and the counterweight are (also, since there is no relative displacement in the X direction between each optical system V and C and the counter weight) (however, X1, X2, X3 and yl, y2, y3 are each optical system v and C and counterweight X
and the amount of displacement in the y direction), so Equations (5) and (6) result.

Therefore, it follows from equations (4) and (7), where δx can be arbitrarily selected.

Here, since W1, W2, W3, θ1, θ2, T, and γ can be set in advance at the time of design, the following is obtained.

Therefore, it is sufficient to design the shape of the composite cam groove 22e so as to satisfy the formula aω.

As described in detail above, the present invention provides a cam groove that regulates a means for canceling the acting force exerted by the movable optical system for zooming, which occurs due to a change in the attitude of the zoom lens, when the movable optical system Since it is provided in the cylindrical member that drives the motor, the following advantages can be obtained compared to the conventional structure mentioned above. That is, (1) during zooming, each movable optical system and the means for canceling the above acting force are both driven and controlled by the same member; therefore, the effect of the above optical system during zooming operation is (2) Since the two types of movement systems are controlled by the same member, there is no discomfort during operation. (3) The above-mentioned conventional Since there is no need for an additional cam cylinder like that found in zoom lenses, it is possible to prevent the structure of the zoom lens mechanism from becoming complicated, and it is also possible to prevent the zoom lens itself from increasing in size. (4) For example, when performing servo control using a servo motor, etc., the load on the motor as a drive source is reduced, so a small output drive source is sufficient, and At the same time, load fluctuations are reduced, making it possible to have a highly accurate servo system, and furthermore, it is possible to suppress the noise caused by the power transmission and delay mechanism to a minimum (5) No additional cam cylinder is required. Therefore, very beneficial advantages such as being able to suppress the increase in the cost of the entire zoom lens can be obtained.

As shown in the embodiment of the drive cylinder in Fig. 8, if the counter weight is reduced to one, the mechanical parts related to the counter weight are also reduced, so that the zoom lens can be improved. This will further promote the simplification of the structure of the mechanism, the miniaturization of the zoom lens itself, and the cost reduction of the zoom lens as a whole. Since only one synthetic cam groove is required for the cam groove, the cost can be significantly reduced in terms of machining.

In addition, as in each embodiment, when machining the cam grooves or regulation grooves in the drive cylinders 22 (FIGS. 3 and 8) and 27 (FIG. 6), these are If it is formed on the inner or outer periphery of the cam without penetrating the outer periphery or the inner periphery, respectively, (1) deformation or distortion of the cylinder due to cam groove machining can be prevented, and the precision of the cam can be improved. (2) Since the rotation angle of the cam groove can be increased, it is possible to design a large curvature of the cam, which results in smooth operation and can reduce cam accuracy errors (3) Advantages such as the ability to increase the strength of the cam cylinder can also be obtained.

In the above description, the cam groove of the balancer has been described as having a curved shape, but it may also have a straight shape. Furthermore, it is of course possible to use the cam as a protrusion instead of a groove, that is, to reverse the unevenness of the mating member.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing the structure of a conventional zoom lens, particularly the main parts related to the present invention. 2 to 4 show a first embodiment of the present invention. FIG. 2 is an external perspective view of the main parts, FIG. 3 is a developed view of the optical system drive cylinder, and FIG. The figure is a sectional view showing details of the internal structure of the zoom lens. Figures 5 to 7 are
This shows a second embodiment of the present invention, and FIG. 5 is an external perspective view of the main parts thereof, and FIG. 6 is a developed view of the optical system drive cylinder.
FIG. 7 is a sectional view showing details of the internal structure of the zoom lens. FIG. 8 is a developed view of the driving cylinder of the optical system 1 when the counter weight is reduced to one in relation to the first embodiment. FIG. 9 is a virtual diagram used in theoretical calculations when determining the shape of the cam groove for regulating the counterweight by mechanical analysis when the number of counterweights is reduced to one. V, C...Movable optical system for zooming, 21,2 "...゜゜゜Fixed cylindrical member, 22
, 22''...゜゜゜゜Cylindrical member for driving the movable optical system for zooming, 29, 32...゜Means (counter weight) for canceling the acting force due to the movable optical system for zooming, 22c, 22d , 220, 22'C, 22'd
...Cam groove for regulating counter weight, 2
2a, 22b, 2'A, 2llb゜''゜゜cam groove for zooming, 21a, 21b, 227a, 22''b...
... A regulating groove for regulating the movable zoom optical system in a direction substantially along the optical axis.

Claims (1)

[Scope of Claims] 1. A variable power lens, a correction lens, a holding barrel housing each of the lenses, a fixed barrel in which a cam groove or a linear guide groove is formed, and a fixed cylinder in which a linear guide groove or a cam groove is formed. In a zoom lens barrel having a rotating barrel and a connecting means that engages at the intersection of the cam groove and the linear guide groove and connects the holding barrel and the rotating barrel, the weight means is moved in a direction parallel to the optical axis. a weight cam groove for regulating the position of the weight means is formed in the rotary cylinder or the fixed cylinder, and a weight cam groove for the weight of the weight means and the rotary cylinder or the fixed cylinder. The cam grooves are connected by a connecting means, and the weight cam groove is configured to move the weight in a direction that cancels out the combined force of the acting forces of the lenses caused by the movement of the variable power lens and the correction lens due to a zooming operation. A zoom lens moving device characterized in that the means is configured to move. 2. The weight means consists of two weight means, one for the variable power lens and one for the correction lens, and the cam groove for the weight of the rotating barrel regulates the position of the weight means for the variable power lens. and a correction cam groove that regulates the position of the correction lens weight means. 2. The zoom lens moving device according to claim 1, wherein the weight means and the correction cam groove are each connected by a connecting means.