JPH06160697A - Zoom lens driving device - Google Patents

Abstract

PURPOSE:To form six guide grooves provided in a lens barrel in order to respectively guide three groups of movable lenses constituting a zoom lens and to accurately guide the lenses in the six guide grooves. CONSTITUTION:The zoom lens is constituted of a 1st lens group, a 2nd lens group and a 3rd lens group attached to lens frames 10 to 12, respectively, and rollers 16 to 18 engaging in the guide grooves 24 of the lens barrel are provided at three spots in a circumferential direction and at two spots in an optical axis direction in the respective lens frames 10 to 12. Six guide grooves 24 are provided in the lens barrel, and three guide grooves 24a, 24c, and 24e are common to the roller 16 of the lens frame 10 and the roller 17 of the lens frame 11, the rollers 16 and 17 are alternately arranged. Other three guide grooves 24b, 24d and 24f are provided to guide the roller 18 of the lens frame 12, and all the rollers can be arranged in the optical axis direction at sufficient intervals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens driving device having three movable lens groups in a lens unit of a television camera.

[0002]

2. Description of the Related Art A television camera is composed of a camera body provided with image pickup means and the like, and a lens unit.
The lens unit is composed of three types of lenses, a focus lens, a zoom lens, and a master lens, in order from the subject side. The zoom lens is usually composed of two or three lens groups. When the zoom lens is composed of two lens groups, by moving each of these lens groups in the direction of approaching and separating from each other in the optical axis direction. I am trying to perform a zooming operation. Further, when the zoom lens is composed of the three lens groups, the intermediate lens is a fixed lens, and the first and third lens groups located on the subject side and the image forming side are movable lenses. It is common to control these zoom lenses by moving these movable lenses in the optical axis direction.

Each lens group constituting the zoom lens is mounted in a separate lens frame, and is assembled by being inserted into the lens barrel. A cam pin is provided on the lens frame of the movable lens group in each lens group so as to project from the lens barrel, and is engaged with the groove cam of the cam barrel fitted to the lens barrel. Further, as a guide for accurately moving the lens group in the optical axis direction of the mounted lens frame, a guide groove is formed on the inner surface of the lens barrel in the optical axis direction, and the guide groove is provided in the lens frame. The rollers are fitted together. Here, since the lens group must be held in an extremely stable state without tilting or the like, the rollers of each lens frame are arranged at three positions every 120 ° in the circumferential direction and at predetermined intervals in the moving direction. Therefore, six guide grooves are formed in the lens barrel, and two rollers are respectively rolled in each guide groove.

[0004]

By the way, in recent years, with the development of so-called high-definition high-definition television and the like, there has been a strong demand for improvement in the quality of images captured by a television camera. In order to meet this request, it is necessary to make all the lens groups of the zoom lens composed of three groups movable so as to move all the lens groups of the three groups during the zooming operation.

Of course, in order to move all the three groups, it is necessary to provide three grooved cams in the cam barrel.
Rollers for guiding the lens frame of each lens group and guide grooves formed on the inner surface of the lens cylinder are required at three locations in the circumferential direction, for a total of nine locations. Forming 9 guide grooves on the inner surface of the lens barrel in this way is not only complicated and troublesome to process, but also this lens barrel is dedicated to a lens for special shooting such as high-definition Therefore, the lens unit for a normal television camera cannot be diverted.

The present invention has been made in view of the above points, and an object of the present invention is to guide three movable lens groups simply by forming six guide grooves in the lens barrel. To do so.

[0007]

In order to achieve the above-mentioned object, the present invention comprises three movable lens groups, each movable in the optical axis direction. In order to move in the direction, three lens frames are provided. Each of these lens frames is provided with three rollers in the circumferential direction and two rollers in the optical axis direction, and these rollers are provided on the inner surface of the lens barrel. Of the movable lens group, which is provided in the second movable lens group and is engaged with a guide groove that is long in the optical axis direction to displace the movable lens group in the optical axis direction to perform a zooming operation. Each of the two rollers arranged in the optical axis direction on the lens barrel of the movable lens group has one roller between two rollers of the other movable lens group, and the other roller of the other movable lens group. By arranging on the extension line of the position of the roller In the second movable lens group, the rollers of the first movable lens group and the third lens group of the movable lens groups are engaged with different guide grooves, respectively. Two rollers provided at positions along the optical axis are provided so as to be shifted in phase by a predetermined angle in the circumferential direction, one of which is a guide groove for the first movable lens group, and the other is a third movable lens. It is characterized in that it is configured to be engaged with the guide groove for the group.

[0008]

If the first, second and third lens units are arranged from the subject side, the moving distance of the second lens unit during zooming operation is relatively small even for a high definition lens. Therefore, the two rollers provided in the optical axis direction of the second lens group are provided so as to sandwich one of the two rollers of the first or third lens group, and the other is positioned on the extension line thereof. . As a result, the guide groove for guiding the roller of the second lens group is formed into the first groove.
Since it can be shared with the guide groove of the roller of either the lens of the third group or the third group, and the distance between the two rollers in the optical axis direction is secured to some extent,
The stability of the lens is not impaired.

Further, the rollers provided at two positions in the optical axis direction of the second lens group are arranged at a predetermined angle in the circumferential direction, for example 60.
° The structure is provided with the phases shifted, and one roller is the first
By engaging the guide groove for the lens group and the other roller in the guide groove of the third lens group,
It is possible to share the guide groove. In this case, the roller located on the image forming side of the second lens group is also used as the guide groove of the first lens group, and the roller located on the subject side is also used as the guide groove of the third lens group. Not only the distance between the rollers of the first and third lens groups but also the distance between the rollers of the second lens group can be set sufficiently, and the stability of each lens group can be obtained.

By adopting the above structure, it is sufficient to form six guide grooves on the inner surface of the guide cylinder.
Therefore, the structure of the lens barrel is simplified, and the structure is the same as the lens barrel for a zoom lens of the type that moves the two lens groups.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. First, FIG. 1 shows the lens configuration of the lens unit. In the figure, 1 is a focus lens, 2 is a zoom lens, and 3 is a master lens. The zoom lens 2 is composed of a first lens group 2a, a second lens group 2b and a third lens group 2c each of which is composed of one to several lenses, and the first lens group 2a is on the subject side and The three lens group 2c is arranged on the image forming side.
These first to third lens groups 2a to 2c are movable lens groups movable in the optical axis direction.

Next, a drive mechanism for the first to third lens groups 2a to 2c constituting the zoom lens 2 will be described with reference to FIGS. Reference numeral 10 is a first lens supporting the first lens group 2a.
Lens frame, 11 is a second lens frame that supports the second lens group 2b, and 12 is a third lens frame that supports the third lens group 2c. Further, 20 is a lens barrel, and 21 is a cam barrel.

Cam pins 13, 14 and 15 are provided on the respective lens frames 10, 11 and 12 so as to project therefrom, and the cam pins 13 to 15 are provided with a long hole 2 formed in the lens barrel 20.
It extends through 2a to 22c and engages with grooved cams 23a to 23c provided on the cam barrel 21. Therefore, the cam barrel 21
The lens frames 10 to 12 can be moved in the optical axis direction by rotating the lens frame manually or by driving means such as a motor. And this lens frame 10
Rollers 16 to 18 are provided on the outer surface of each lens frame 10 to 12 so as to guide them accurately to move in the optical axis direction.
Reference numeral 8 is formed on the inner surface of the lens barrel 20 and is configured to engage with a guide groove 24 which is long in the optical axis direction. Here, rollers 16 to 1 provided on each lens frame 10 to 12
8 are provided at three places every 120 ° in the circumferential direction,
Further, it is provided at two positions in the front and rear in the optical axis direction. In addition, a pair of front and rear rollers are provided at each position, and the rollers formed by the front and rear pairs alternately contact the left and right walls of the guide groove 24.

With this structure, when the cam barrel 21 is rotated, the lens groups 2a to 2c, which are the three groups of the zoom lens 2, are moved, and the zooming operation is performed. By displacing the lenses of all three groups during the zooming operation, the aberrations are sufficiently corrected, and the image quality of the captured image is significantly improved. When each of the lens frames 10 to 12 moves, it is necessary to prevent the lens held therein from being displaced or tilted with respect to the optical axis. Here, each of these lens frames 10 to 1
Rollers 16 to 2 are provided at three locations at intervals of 120 ° in the circumferential direction and at two locations at predetermined intervals in the optical axis direction.
Since 18 is engaged with the guide groove 24 and is guided by the guide groove 24, there is no risk of misalignment, tilting, and the like, and displacement occurs in a stable state.

Here, in order to make the lens frames 10 to 12 more stable, the distance between the pair of rollers arranged in the axial direction of the rollers 16 to 18 provided in each of the lens frames 10 to 12 is made as long as possible. There is a need. Also, 3
Despite the displacement of all the lens groups 2a to 2c, only six guide grooves 24 for guiding the rollers are provided.

Therefore, six guide grooves 24 are provided.
In order to hold the rollers at intervals that can stably support the lens frame, the rollers are arranged as shown in FIG. In the figure, each roller 16-1
Depending on the position in the circumferential direction and the position in the optical axis direction at 8, the subscripts of f for the subject side and r for the image forming side are used. Further, the guide grooves 24 are denoted by reference numerals a to f, respectively.

Thus, the lens frame 10 of the first lens group 2a
Three rollers 16f are attached to itself, three extension parts 10a are continuously provided toward the image forming side, and rollers 16r are attached to the extension parts 10a. Further, the lens frame 11 of the second lens group 2b is continuously provided with an extension 11a toward the subject side, and the roller 17 is provided on the extension 11a.
The extension part 11b is continuously provided toward the image forming side, and the rollers 17r are respectively attached thereto. Further, the roller 18r is mounted on the lens frame 12 of the third lens group 2c, and 18f is mounted on the extension 12a toward the subject side. Thus, the rollers 16f and 16r of the lens frame 10 and the rollers 17 of the lens frame 11 are provided in the guide groove 24a.
f and 17r are engaged. The rollers 18f and 18r of the lens frame 12 are engaged with the guide groove 24b. The guide grooves 24c to 24f are shown below in the order shown.
Each roller is engaged with. In short, the guide groove 24
Reference numerals a, 24c, and 24e are guide grooves common to the rollers of the lens frame 10 and the lens frame 11, and guide grooves 24b, 24d, and 24f are guide grooves for guiding the rollers of the lens frame 12. And the common guide groove 2
4a, 24c, 24e, for example, the guide groove 24
In a, the roller 16f of the lens frame 10, the roller 17f of the lens frame 11, the roller 16r of the lens frame 10 and the roller 17r of the lens frame 11 are arranged in this order, that is, the roller of the lens frame 10 and the roller of the lens frame 11 are alternately arranged. It is arranged.

With this structure, all the three groups of lenses 2a, 2b, 2c can be made movable by simply forming six guide grooves on the inner surface of the lens barrel 20. Therefore, the lens barrel 20 can be easily processed, and the lens barrel can be commonly used as a lens barrel in which only two lenses of the three lens groups are movable lenses. Here, the roller must hold the lens frame in a stable state and have a structure in which the lens mounted on the roller does not fall over, but the lens frames 10 and 1 that share the guide groove.
Since the No. 1 rollers are arranged alternately, it is possible to arrange the rollers at a sufficient interval. However, if the rollers are alternately arranged in this way, the lens frames 10, 1
Although the relative movement amount between the first lens group 2a and the second lens group 2b is restricted, the first lens group 2a and the second lens group 2b do not move much in the directions of approaching and separating when relatively moving during the zooming operation. It suffices to provide a relatively small clearance between the rollers so that relative movement is possible, so that there is no problem in space.

Next, FIG. 5 shows another embodiment of the present invention.
In this embodiment, the roller 17 of the second lens group 2b
The guide groove for use is configured such that one side is also used as the guide groove of the first lens group 2a and the other side is also used as the guide groove of the third lens group 2c. That is, the lens frame 11 of the second lens group 2b has extension portions 11a 'and 11b' for attaching the roller 17f located on the subject side and the roller 17r located on the image forming side, respectively.
There are three locations for each degree, but these extensions 11
The a'and the extension portion 11b 'are provided at a position shifted in phase by 60 °. A roller 17f is attached to the extension portion 11a ′ protruding toward the subject side, and the extension portion 11b ′ is also attached.
A roller 17r is attached to the. And extension 1
The roller 17f of 1a 'is the guide groove 2 of the third lens group 2c.
The rollers 17r of the extension 11b 'are engaged with the guide grooves 24a, 2b of the first lens group 2a.
4c and 24e are engaged.

With this construction, the two rollers 16f, 16r, 17f, 17r and 18f, 18r, which are provided on the lens frames 10 to 12 at different positions in the optical axis direction, can be extremely closed. Allows for sufficient spacing to hold stably. Moreover, the third
The roller 17f engaged with the guide grooves 24b, 24d, 24f for the lens group 2c is disposed further on the subject side than the roller 18f located on the subject side of the third lens group 2c, and at a predetermined distance from it. And guide grooves 24a, 24c, 24e for the first lens group 2a
The roller 17r engaged with is closer to the image forming side than the roller 16r located on the image forming side of the first lens group 2a,
Because it is arranged with a predetermined interval,
Even if all three groups are moved at the same time, they do not interfere with each other.

[0021]

As described above, according to the present invention, in the three movable lens groups that constitute the zoom lens, the movable lens groups are provided at two positions separated from each other in the optical axis direction and at three positions in the circumferential direction. Since the rollers are provided so that the rollers at the two positions provided on the lens barrel of the second movable lens group are also used as the guide grooves for the rollers of the other movable lens group, they are formed on the inner surface of the lens barrel. It is only necessary to provide six guide grooves for the guide groove, which simplifies the machining of the guide groove, and enables sharing with the lens barrel of a zoom lens of the type that moves only the two lens groups. Therefore, each of the two rollers arranged in the optical axis direction provided on the lens barrel of the second movable lens group has one roller located between the two rollers of the other movable lens group and the other roller. Of the movable lens group The first movable lens group and the third lens group are engaged with different guide grooves, and the second movable lens group is arranged at a position in the optical axis direction. If two rollers are provided so as to be out of phase with each other by a predetermined angle in the circumferential direction, and one is engaged with the guide groove for the first movable lens group and the other is engaged with the guide groove for the third movable lens group. Therefore, even if all the lenses in the three groups are moved at the same time, they do not interfere with each other, and the two rollers arranged at different positions in the optical axis direction can be sufficiently spaced. Thus, the effects of improving the stability of each lens are exhibited.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a lens unit.

FIG. 2 is a sectional view showing a zoom lens driving mechanism.

FIG. 3 is a perspective view showing a combined state of lens frames.

FIG. 4 is a development view showing a positional relationship between a lens frame, a roller and a guide groove.

FIG. 5 is a development view showing a positional relationship among a lens frame, rollers, and guide grooves according to a second embodiment of the present invention.

[Explanation of symbols]

 2 zoom lens 2a 1st lens group 2b 2nd lens group 2c 3rd lens group 10,11,12 lens frame 16-18,16f-18f, 16r-18r roller 20 lens barrel 21 cam barrel 24,24a-24f guide groove

Claims (2)

[Claims] 1. A movable lens group of three groups, each of which is movable in the optical axis direction, is provided, and three lens frames are provided to individually move the movable lens group in the optical axis direction,
Rollers are provided on each of these lens frames at three locations in the circumferential direction and at two locations in the optical axis direction. These rollers are provided on the inner surface of the lens barrel, and are provided in a guide groove extending in the optical axis direction. In the arrangement in which the movable lens groups are engaged with each other to be displaced in the optical axis direction to perform the zooming operation, each of the movable lens groups arranged in the optical axis direction provided in the lens barrel of the second movable lens group. The two rollers share one guide groove by arranging one of them at a position between the two rollers of the other movable lens group and the other on an extension of the roller position of the other movable lens group. A zoom lens driving device having a configuration. 2. A movable lens group of three groups each movable in the optical axis direction, and three lens frames are provided to individually move the movable lens group in the optical axis direction,
Rollers are provided on each of these lens frames at three locations in the circumferential direction and at two locations in the optical axis direction. These rollers are provided on the inner surface of the lens barrel, and are provided in a guide groove extending in the optical axis direction. In the case of engaging and displacing each of the movable lens groups in the optical axis direction, the rollers of the first movable lens group and the third lens group of the movable lens groups are engaged with different guide grooves. Further, two rollers provided at positions in the optical axis direction in the second movable lens group are provided so as to shift a predetermined angular phase in the circumferential direction, and one of them is used as a guide groove for the first movable lens group. And a zoom lens drive device characterized in that the other is engaged with a guide groove for the third movable lens group.