JPS5815775B2 - Single-axis operated zoom lens zoom device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a zoom device for a one-shot operation type zoom lens.

As is well known, a single-axis operated zoom lens is a lens in which zooming and focusing are performed by pushing, pulling and rotating a single operating axis, respectively, and is mainly used in industrial television cameras (
ITV).

When making such a zoom lens, generally speaking, ordinary I
A TV manual zoom lens is often slightly modified and equipped with a zoom device and a focus device that share a single operating axis.

For example, FIGS. 1 and 2 show a conventional uniaxially operated zoom lens, where 1 is a normal ITV manual zoom lens, 2 is a mount holder for attaching it to a camera,
3 is a case that houses a zoom device and a focus device, and when the operating shaft 4 is rotated, focusing is performed by a focusing device (not shown);
When pushed or pulled, the wire 6 is guided by the pulleys 7, 8, 9, and 10 together with the movable fitting 5, and the zoom lens 1
The zoom ring 11 rotates to perform zooming.

As the zoom ring 11, the zoom operation ring included in the zoom lens 1 may be used, or a ring as shown in FIG. 2, for example, may be fixed on the zoom operation ring.

By the way, in general, when constructing a uniaxially operated zoom lens, the relationship expressed by the following equation (1) must hold.

L≧2 P+ 1 +M+A (1,) In other words, when using the zoom lenses shown in Figures 1 and 2, L is the length of the zoom lens 1 (from its front end to the flange back position FB), 1 is the operation The push/pull strokes PlM and A required for zooming of the shaft 4 are determined by the pulley 7.
8.Mount presser 2, moving bracket 50 width, konoke)
If the relationship in the formula does not hold, the case 3 will protrude ahead of the front end of the zoom lens 1, and the angle of view α of the zoom lens 1 will change.
A part of the lens is blocked by this, making it impossible to obtain a practical uniaxially operated zoom lens.

Note that the goo leaf 8, the mount presser 2, and the movable metal fitting 5 are essential components of any currently known type of uniaxially operated zoom lens, and each has its own width.

However, in the uniaxially operated zoom lens shown in FIGS. 1 and 2, the push/pull stroke 1 of the operating shaft 4 is
When the diameter of 1 is D, the rotation angle (radian) is θ, and the thickness of wire 6 is ignored, 1=Dθ/2
(2), and D and θ are values unique to the zoom lens 1 that is to be changed to a uniaxial zoom lens, that is, a −-axis operable zoom lens, and therefore are uniquely determined depending on the zoom lens 1. Put it away.

In other words, the value on the right side of equation (1) above is uniquely determined by the zoom lens 1.

On the other hand, L on the right side of the Uemachi equation 1) also has a unique value depending on the zoom lens 1.

This means that in a zoom lens whose total length is short, even if it is attempted to make it uniaxial, the relationship expressed by the upper eyelid equation 1) may not hold.

In particular, recent zoom lenses are required to be compact on the one hand (i.e. shortened in length L), and on the other hand are required to be bright lenses with small aperture f-numbers (i.e. lenses with large D) and There is a need for a high-magnification zoom lens with a large ratio (that is, a lens with a large θ), and it is becoming increasingly difficult to make it uniaxial.

Therefore, the present invention makes it possible to freely determine the push/pull stroke for zooming of the operation axis during design, thereby making it possible to freely define the push/pull stroke for zooming of the operation axis, thereby making it possible to use the
The purpose of this project is to provide a zoom device for a uniaxially operated zoom lens that makes it possible to use a single-axis manual zoom lens for V. By connecting the operating shaft with a wire guided by a pulley, the rotating shaft rotates according to the amount of push and pull of the operating shaft, and rotation is transmitted between the rotating shaft and the zoom ring of the zoom lens. The present invention is characterized in that a mechanism is provided so that the zoom ring rotates in accordance with the amount of rotation of the rotating shaft, and the drum and rotation transmission mechanism are given the role of stroke conversion means.

That is, according to the zoom device of the present invention, by selecting the diameter of the drum and the basic circle diameters of the zoom ring side and rotating shaft side of the rotation transmission mechanism at the time of design, it is possible to freely select the push/pull stroke of the operating shaft. Therefore, the relationship of equation (1) above can be satisfied even when any zoom lens is made uniaxial.

On the other hand, uniaxially operated zoom lenses generally require a wire and a pulley to guide it, but if the number of pulleys is large, not only will friction increase, but the wire will also become longer, making it difficult to operate the wire. The amount of expansion of it due to the load also increases, making it difficult to perform accurate zoom linking in accordance with the amount of push and pull of the operating shaft.

In order to overcome this drawback, it is of course best to reduce the number of pulleys as much as possible, but in the conventional zoom lenses shown in Figures 1 and 2, reducing the number of pulleys to, for example, two, will allow sufficient space between the pulleys. Therefore, a zoom ring that is long in the axial direction is required, which obstructs the connection between the focus ring and the focus device. Since they must be aligned, the wires 6 intersect in a V-shape when viewed from the axial direction, and the arrangement of the focus device itself is also hindered.

As a result, the uniaxially operated zoom lens shown in FIGS. 1 and 2 generally requires at least four pulleys and cannot avoid the above-mentioned drawbacks.

Therefore, another object of the present invention is to reduce the number of pulleys that guide the wire as much as possible to reduce friction on the pulleys, and at the same time shorten the length of the wire, which enables accurate zooming. The purpose is to provide a zoom device, and the purpose is to provide a zoom device in which a rotating shaft is arranged on the side of a zoom link and an operating shaft, and two pulleys are arranged so that the direction of their guide grooves coincides with the tangential direction of the drum. This was achieved by arranging the

The present invention will be explained below with reference to illustrated embodiments.

3 and 4 show an embodiment of the invention, but in these figures, the focus device is omitted to avoid confusion, and the same parts as shown in FIGS. 1 and 2 are The same reference numerals are given.

That is, in this embodiment, the rotating shaft 1 is parallel to the operating shaft 4.
3 is supported, and a small gear 14 is fixed at the center of this L rotating shaft 13, and drums 15 and 16 are fixed at both ends.

The small gear 14 meshes with a large gear 17 fixed on the outer periphery of the zoom ring 11, and the rotating shaft 13 meshes with these gears 14.
17 to the zoom ring 11.

On the other hand, the wire 6 is wound around the drums 15 and 16 in different winding directions, hooked onto a pin 18, and then fixed by a presser metal fitting 19.

This wire 6 is guided by pulleys 7.8 and given an appropriate tension, and is also fixed to the movable fitting 5 by a fixing fitting 20 at a portion of the straight portion 6a located between the pulleys 7.8.

The direction of the guide grooves 7a, 8a of the pulley 7.8 coincides with the tangential direction of the circumferential surfaces of the drums 15, 16, as shown in FIG.
The straight portion 6a of the wire 6 is parallel to the operating shaft 4.

Further, the rotating shaft 13 is connected to the zoom ring 11 as shown in FIG.
The wire 6 and the operating shaft 4 are connected to each other by the fixing fitting 5.

In this case, a focus device (not shown) is usually provided around the operating shaft 4, but since the wire 6 is located below the rotation shaft 13, the operation of the focus device is not hindered by the wire 6.

In this embodiment, when the operating shaft 4 is pushed or pulled, the wire 6 is moved together with the movable fitting 5 according to the amount of pushing or pulling, and the drum 1 is moved.
5 and 16 rotate together with the rotating shaft 13.

This rotation of the rotation axis is then transmitted to the zoom ring 11 by gears 14 and 17, and zooming is performed according to the amount of rotation of the zoom ring 110.

Furthermore, when the operating shaft 4 is rotated, the zoom device remains in the same position and the focus device operates instead.

Focusing is performed by moving the camera.

By the way, in this embodiment, dl: pitch circle diameter d2 of large gear 17: pitch circle diameter d3 of small gear 14: diameter θ of drums 15, 16: rotation angle (radian) of zoom ring 11: 1: rotation axis 130 Rotation ratio (θ1/2π) l: push/pull stroke of operating shaft 4 11: arc length of large gear 17 12: arc length of small gear 14, then l = 1πd3 (3) 11 = d1θ/2 (4 )12=to1
πd2 (5) holds true.

Since 11-12, 1 = d, d3θ/2d2 (6) can be obtained from equations (2), (3), and (4).

In the conventional zoom device shown in FIGS. 1 and 2, the push/pull stroke l of the operating shaft is expressed by the above equation (2), so the push/pull stroke in the conventional zoom device and that in this embodiment are The stroke ratio of the push/pull stroke is given by Kl-Dd2/d1d3 (7).

This equation (7) is Dd2>d1d3, that is, D>d1
In the case of d3/d2, this indicates that the push/pull stroke 1 is shorter than that of a conventional uniaxially operated zoom lens.
It will be understood from this that by appropriately selecting dl, d2, and d3, the push/pull stroke (2) can be determined, and the above relationship (1) can always be satisfied.

In other words, even when a small and bright zoom lens or a small and high magnification zoom lens is made uniaxial, d1d2d
If 3 is appropriately selected, it is possible to satisfy the relationship of the above equation (1) and provide a practical uniaxially operated zoom lens.

Also, if the push/pull stroke 1 has enough margin for the total length of the zoom lens, that is, if the left side of equation (1) above is sufficiently smaller than the right side, then d1d2d3 can be changed to Dd.
By selecting l<d1d3, it is possible to make the push/pull stroke 1 longer as necessary.

On the other hand, separately from this, a rotation shaft 13 is arranged on the side of the zoom ring 11 and the operation shaft 4, and the wire 6 is connected to the rotation shaft 1.
Since it is fixed to drums 15 and 16 fixed to 3,
Even if the wire 6 is guided by two pulleys 7 and 8, there is no need to design the zoom ring 11 long, and the wire 6
It is also possible to avoid interference with the operation of the focus device provided between the operating shaft 4 and the zoom ring 110.

As a result, not only the friction acting on the wire 6 is reduced, but also the length of the wire 6 can be shortened, and the amount of elongation of the wire due to the load is reduced accordingly, so that accurate zooming is possible.

Although the present invention has been described above with reference to the illustrated embodiments, the present invention is not limited to the above-described embodiments.

For example, in the above embodiment, the small gear 14 and the large gear 17 may be replaced with other rotation transmission mechanisms using timing belts, or the small gear 14 and the large gear 17 may be mounted on the drum 15 or 16 and the zoom ring 17, respectively. It may also be formed directly.

If the small gear 14 is fixedly mounted on the drum or formed directly on the drum, the drums 15 and 16 do not need to be separated and can be formed integrally.

As described above, the zoom device for a uniaxially operated zoom lens according to the present invention includes a drum fixed to a rotating shaft supported parallel to the operating shaft, and a drum provided to transmit the rotation of the rotating shaft to the zoom ring of the zoom lens. The rotation transmission mechanism serves as a means for converting the push/pull stroke of the operating shaft, and by selecting the diameter of the drum, the zoom ring of the rotation transmission mechanism, and the basic circle diameter on the rotation shaft side, it is possible to It becomes possible to use a single-axis manual zoom lens for ITV.

In addition, the rotation axis is placed to the side of the zoom ring and operation axis,
Since the wire is fixed on the drum, there is no need to move the zoom ring for a long time even if the wire is guided by two pulleys, and the wire does not interfere with the operation of the focusing device. Not only does the friction acting on the wire become smaller, but the length of the wire can be shortened,
The amount of elongation is also reduced, making accurate zooming possible.

[Brief explanation of drawings]

Fig. 1 is a side view showing a zoom device of a conventional uniaxially operated zoom lens, Fig. 2 is a perspective view of the main parts in Fig. 1,
FIG. 3 is a side view of a zoom device for a uniaxially operated zoom lens according to the present invention, and FIG. 4 is an explanatory diagram of the zoom device of FIG. 3 viewed from the axial direction of the operating shaft. 1...Zoom lens, 3...Case, 4...Operation axis, 5
...Moving bracket, 6...Wire, 7,8゜9.10...
Pulley, 7, 8... Guide mechanism, 11... Zoom ring, 13... Rotating shaft, 14... Small gear, 15, 16... Drum, 17... Large gear.

Claims (1)

[Claims] 1. In a zoom device for a uniaxially operated zoom lens in which zooming is performed by pushing and pulling the operating shaft and focusing is performed by rotating the operating shaft, a rotating shaft supported parallel to the operating shaft;
A drum fixed to this rotating shaft, a wire connected to the outer periphery of this drum and the operating shaft that converts the linear motion of the operating axis by pushing and pulling into the rotating motion of the rotating shaft, and a zoom lens that converts the rotating motion of the rotating shaft into the rotating motion of the rotating shaft. A zoom device comprising: a rotation transmission mechanism for transmitting transmission to a zoom ring; and a guide mechanism for the wire comprising a plurality of pulleys.