JP3198679B2 - Zoom lens drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art A television camera comprises 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. A zoom lens is usually composed of two or three groups of lenses. When composed of two groups of lenses, by moving each of these lens groups in the direction of the optical axis toward and away from each other. The zooming operation is performed. Further, when a zoom lens is composed of three groups of lenses, the intermediate lens is a fixed lens, and the first and third lens groups on the subject side and the image forming side are movable lenses. In general, control is performed so that a zooming operation is performed by moving these movable lenses in the optical axis direction.

[0003] Each lens group constituting a zoom lens is mounted on a separate lens frame, and assembled by being inserted into a lens barrel. A cam pin is provided on the lens frame of the movable lens group in each lens group so as to protrude from the lens barrel, and is engaged with the groove cam of the cam barrel fitted to the lens barrel. In addition, a guide groove is formed in the inner surface of the lens barrel in the optical axis direction as a guide for accurately moving the lens frame in which the lens group is mounted in the optical axis direction, and the guide groove is provided in the lens frame. The rollers are fitted. Here, since the lens group must be kept in an extremely stable state without falling or the like, for each lens frame, rollers are provided at three places in the circumferential direction at every 120 ° and at predetermined intervals in the moving direction. Therefore, six guide grooves are formed in the lens barrel, and two rollers roll in each guide groove.

[0004]

In recent years, along with the development of high-definition television, which is also called so-called high-definition television, etc., there has been a strong demand for improvement in the quality of images photographed by television cameras. In order to meet this requirement, it is necessary to make all the lens units of the zoom lens composed of three units movable and to move all the three lens units during the zooming operation.

[0005] In order to move all of the three groups, three groove cams in the cam cylinder must be provided.
A roller for guiding the lens frame of each lens group and a guide groove formed on the inner surface of the lens cylinder are required at three places in the circumferential direction, that is, nine places in total. Forming nine guide grooves on the inner surface of the lens barrel in this way not only makes the processing complicated and troublesome, but also this lens barrel is dedicated to the lens for special shooting such as for high-definition As a result, a lens unit for a normal television camera cannot be used.

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

[0007]

In order to achieve the above-mentioned object, the present invention provides a lens barrel in which, in order from an object side,
Each of the first lens group, the second lens group, and the third lens group
Mounted on a lens frame that is movable in the optical axis direction.
These three lens frames have three positions in the circumferential direction,
Rollers are provided at two places in the optical axis direction.
Is provided with a guide groove elongated in the optical axis direction.
By engaging the rollers with these guide grooves,
Zooming by displacing each lens group in the optical axis direction
The first lens group includes three lenses.
The extension of the part is extended toward the imaging side, and
Roller is formed on each of these extensions, and the guide cylinder
Has three guide grooves that engage the rollers of each extension.
In the third lens group, three extended portions
Side, and each of the rollers is
Formed in the long part,
Three guide grooves to engage the rollers of each extension
The second lens group is directed toward the subject side and the image forming side.
Form multiple extensions and install each roller on each of these extensions.
In addition, these rollers are replaced by the rollers of the first lens group.
The engaging guide groove or the roller of the third lens group is engaged.
It is characterized in that it is configured to engage with one of the guide grooves that match .

[0008]

When the first, second and third lens groups are arranged from the object side, the moving distance of the second lens group during zooming operation is relatively small even for a high-vision lens. Thus, two rollers provided in the optical axis direction of the second lens group are provided so as to sandwich one of the two rollers in the first or third lens group, and the other is positioned on an extension of the roller. . Thereby, the guide groove for guiding the roller of the second lens group is formed in the first groove.
The roller can be shared with the guide groove of the roller of any of the lenses of the group and the third group, and the distance between the two rollers in the optical axis direction is secured to a certain extent.
The stability of the lens is not compromised.

Further, 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 degrees.
° The phase is shifted and one roller is the first
By engaging the guide groove for the lens group and the other roller with the guide groove of the third lens group,
Guide grooves can be shared. In this case, the roller located on the image forming side of the second lens group is shared with the guide groove of the first lens group, and the roller located on the subject side is shared with the guide groove of the third lens group. In addition to the distance between the rollers of the first and third lens groups, the distance between the rollers of the second lens group can be sufficiently set, and the stability of each lens group can be obtained.

By adopting the above configuration, 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 configuration is the same as that of a lens barrel for a zoom lens of a type that moves two groups of lenses.

[0011]

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

Next, a driving mechanism of the first to third lens groups 2a to 2c constituting the zoom lens 2 will be described with reference to FIGS. Reference numeral 10 denotes a first lens supporting the first lens group 2a.
, 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. Reference numeral 20 denotes a lens barrel, and reference numeral 21 denotes a cam barrel.

Each of the lens frames 10, 11 and 12 has a cam pin 13, 14 and 15 projecting therefrom. The cam pins 13 to 15 are elongated holes 2 formed in the lens barrel 20.
It extends through 2a to 22c and engages with groove cams 23a to 23c provided on the cam cylinder 21. Therefore, the cam cylinder 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 of the lens frames 10 to 12 so as to guide the rollers 16 to 12 accurately 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 elongated in the optical axis direction. Here, the rollers 16-1 provided on the lens frames 10-12, respectively.
8 are provided in three places every 120 ° in the circumferential direction,
Further, it is provided at two places in the optical axis direction. Further, a pair of front and rear rollers is provided at each location, and the rollers formed of the front and rear pairs alternately contact the left and right walls of the guide groove 24.

With this configuration, when the cam barrel 21 is rotated, the three lens groups 2a to 2c of the zoom lens 2 move to perform a zooming operation. By displacing all three lenses during the zooming operation, aberrations are sufficiently corrected, and the image quality of a captured image is significantly improved. When each of the lens frames 10 to 12 moves, it is necessary that the lenses held by the lens frames 10 to 12 do not shift or fall with respect to the optical axis. Here, each of these lens frames 10-1
Rollers 16 to 2 provided at two locations at 120 ° intervals in the circumferential direction and at predetermined intervals in the optical axis direction
Since each of the members 18 is engaged with and guided by the guide groove 24, there is no possibility of occurrence of slippage or falling down, and the displacement is performed 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 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.
, Each roller is arranged as shown in FIG. 4 in order to maintain the rollers at an interval capable of stably supporting the lens frame. In the figure, each roller 16-1
According to the position in the circumferential direction and the position in the optical axis direction at 8, the suffix f is used for the object side and the r suffix is used for the image side. Further, reference numerals a to f are used for the guide grooves 24, respectively.

Thus, the lens frame 10 of the first lens group 2a
Three rollers 16f are attached to itself, and three extended portions 10a are continuously provided toward the image forming side, and a roller 16r is attached to the extended portion 10a. The lens frame 11 of the second lens group 2b is provided with an extension 11a extending toward the subject, and a roller 17 is attached to the extension 11a.
f, an extended portion 11b is continuously provided toward the image forming side, and rollers 17r are respectively mounted. Further, a roller 18r is mounted on the lens frame 12 of the third lens group 2c, and an extension 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 17f of the lens frame 11 are provided in the guide grooves 24a.
f, 17r are engaged. The rollers 18f and 18r of the lens frame 12 are engaged with the guide grooves 24b. Hereinafter, the guide grooves 24c to 24f are arranged in the order shown in the drawing.
Are engaged with each other. In short, the guide groove 24
Reference numerals a, 24c, and 24e denote guide grooves common to the rollers of the lens frame 10 and the rollers of the lens frame 11, and guide grooves 24b, 24d, and 24f are guide grooves for guiding the rollers of the lens frame 12. And shared guide groove 2
4a, 24c and 24e, for example, the guide groove 24
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, that is, the rollers of the lens frame 10 and the rollers of the lens frame 11 are alternately arranged. Are located.

With this configuration, all of the three groups of lenses 2a, 2b, and 2c can be made movable lenses only by forming six guide grooves on the inner surface of the lens barrel 20. In addition, processing of the lens barrel 20 is facilitated, and the lens barrel can be shared with a lens in which only two of the three groups are movable lenses. Here, the rollers must hold the lens frame in a stable state and have a structure in which the lens mounted thereon does not fall down, but the lens frames 10 and 1 which share the guide groove.
Since the one rollers are alternately arranged, they can be arranged with a sufficient interval between them. However, when the rollers are alternately arranged in this manner, the lens frames 10, 1
Although the relative movement amount between the first lens group 2a and the second lens group 2b is restricted, since the first lens group 2a and the second lens group 2b do not move much in the direction of approaching / separating during the relative movement during the zooming operation. It is sufficient to provide a relatively small clearance in a range that allows relative movement between the rollers, so that there is no space problem.

Next, FIG. 5 shows another embodiment of the present invention.
In this embodiment, the rollers 17 of the second lens group 2b
One of the guide grooves is shared with the guide groove of the first lens group 2a, and the other is shared with the guide groove of the third lens group 2c. That is, extension portions 11a 'and 11b' are attached to the lens frame 11 of the second lens group 2b by 180 to attach the roller 17f located on the subject side and the roller 17r located on the image forming side, respectively.
Each of the three extension portions 11
a ′ and the extension 11b ′ are provided at positions shifted by 60 ° in phase. A roller 17f is mounted on the extension 11a 'protruding toward the subject, and the extension 11b'
Is mounted with a roller 17r. And extension 1
The roller 17f of 1a 'is the guide groove 2 of the third lens group 2c.
4b, 24d, and 24f, and the roller 17r of the extension 11b 'is connected to the guide grooves 24a, 2d of the first lens unit 2a.
4c, 24e.

With this configuration, the two rollers 16f, 16r, 17f, 17r and 18f, 18r provided at different positions in the optical axis direction on the respective lens frames 10 to 12 can be extremely connected. It will be possible to take a sufficient interval to keep it stable. And third
The roller 17f engaged with the guide grooves 24b, 24d, and 24f for the lens group 2c is disposed at a predetermined distance from the roller 18f located on the object side of the third lens group 2c and on the object side. And guide grooves 24a, 24c, 24e for the first lens group 2a.
The roller 17r engaged with the first lens group 2a 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 at a predetermined interval,
Moving all three groups at the same time does not interfere with each other.

[0021]

As described above, according to the present invention, the three movable lens groups constituting the zoom lens are located at the middle position.
Guides the lens frame of the second lens group to be placed in the optical axis direction
Extension from the lens frame to the subject side and the imaging side.
And the engaging portion of the roller provided on the extension
To guide the lens group or the third lens group in the optical axis direction
Since a structure engaged with the guide groove may be provided at six positions the guide groove formed on the inner surface of the lens barrel, the machining of the guide groove results in easier, move simultaneously all the third lens group Does not interfere with each other, and the two rollers arranged at different positions in the optical axis direction can have a sufficient distance between them, thereby improving the stability of each lens. To play.

[Brief description of the 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 among a lens frame, a roller, and a guide groove.

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

[Explanation of symbols]

 2 zoom lens 2a first lens group 2b second lens group 2c third 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

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-60-10214 (JP, A) JP-A-59-29215 (JP, A) JP-A-57-115509 (JP, A) JP-A-60-210 217320 (JP, A) Japanese Patent Application Laid-Open No. Sho 60-12524 (JP, A) Japanese Utility Model Application No. 2-3622 (Japanese Utility Model Application No. 3-96610) JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02B ^7/ 04-7/ ¹⁰

Claims (3)

(57) [Claims] 1. A lens system comprising :
The lens group, the second lens group, and the third lens group
Attached to an axially movable lens frame and provided
The three lens frames each have three optical axes,
A roller is provided at two places in the direction, and light is
By providing guide grooves that are elongated in the axial direction,
By engaging the rollers with the guide grooves,
The zoom operation is performed by displacing each lens group in the optical axis direction.
In the first lens group, three extended portions are directed toward the image forming side.
And each roller is formed on each of these extensions.
And the guide cylinder is associated with the roller of each extension.
Three guide grooves are formed, and the third lens group has three extended portions facing the subject side.
And each roller is attached to each of these extensions.
In addition to the above, each of these
Three guide grooves are provided to engage with the long roller, and the second lens group is provided with a plurality of guide grooves toward the subject side and the image forming side.
Are formed, and each roller is provided for each of these extensions.
The rollers of the first lens group are associated with these rollers.
Guide groove or roller of the third lens group engages
A zoom lens driving device, wherein the zoom lens driving device is configured to engage with any one of the guide grooves . 2. An apparatus according to claim 1, wherein each of said plurality of extension portions of said second lens group is provided.
The rollers are guides with which the rollers of the first lens group engage.
A groove or a guide groove with which the roller of the third lens group is engaged
Characterized in that it is configured to engage with only one of
The zoom lens driving device according to claim 1, wherein 3. An optical system provided at each extension of the second lens group.
A roller provided at an extension to the subject side,
Of the rollers provided on the extension to the image side,
The roller of the long part is a roller with which the roller of the first lens group engages.
The roller of the extension to the guide groove and to the other side
A configuration in which the rollers of the lens group are engaged with guide grooves
2. The zoom lens device according to claim 1, wherein
Place.