JPH05257050A - Zoom lens device - Google Patents

Abstract

PURPOSE:To make a zoom lens device compact by using space in a side cam system side cam barrel, inserting a driving motor driving the side cam barrel into the space, to be arranged, and further, disposing a zoom resistance plate as a zoom information detecting means and a follower in the gap of the driving motor and the side cam barrel. CONSTITUTION:A driving motor 54 turning the side cam barrel 18 is fitted into a cylindrically formed base 56, the base 56 is inserted into the side cam barrel 18, and a driving motor 56 is inserted into the side cam barrel 18 to be arranged. Further, the zoom resistance plate 68 as the zoom information detecting means and a brush 72 composed of an electrically conductive member and having the follower 70 are arranged in the gap of the driving motor 54 and the side cam barrel 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom lens device, and more particularly to a zoom lens device suitable for a video camera.

[0002]

2. Description of the Related Art Conventionally, the lens barrel structure of a zoom lens device is
The cam barrel is arranged concentrically with the moving lens unit, and the moving lens unit in the cam barrel is moved back and forth by rotating the cam barrel. On the other hand, in recent zoom lens apparatuses, in order to reduce the size and improve the performance, the movable lens group is composed of three or more groups, and the iris is moved along with the zooming of the movable lens group.

However, in order to move three or more movable lens groups or move the iris in the zoom lens device having the above-mentioned lens barrel structure, a large number of cam grooves must be formed in the cam barrel. There are some difficulties in arranging the cam grooves. Therefore, as a zoom lens device that solves such a problem, a side cam system in which a cam barrel is arranged on the side of the moving lens group is adopted. In the side-cam type zoom lens device, three or more lens groups can be easily moved, and the iris is mounted between the movable lens groups via the iris insertion opening formed in the cam barrel as in the conventional case. Since it is not necessary and can be directly arranged between the moving lens groups from the side, the moving iris can be attached without any problem.

[0004]

However, in the conventional side-cam type zoom lens device, since the drive motor for rotating the side-cam barrel is arranged on the side of the side-cam barrel, the zoom is performed by the mounting area of the drive motor. There is a drawback that the lens device becomes large. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a side-cam type zoom lens device capable of making the zoom lens device compact.

[0005]

In order to achieve the above object, the present invention comprises a plurality of lens frame bodies to which a plurality of movable lens groups are attached, and a plurality of support rods supporting the plurality of lens frame bodies. , A side cam barrel which is disposed on the side of the plurality of lens frame bodies and in which each pin formed in each lens frame body is fitted into each groove thereof, and the plurality of lens frame bodies are formed by rotating the side cam barrel. In a zoom lens device comprising a drive motor that moves back and forth along the cam groove in the optical axis direction, the drive motor is inserted and arranged in the side cam barrel.

[0006]

According to the present invention, the drive motor is inserted and arranged in the side cam cylinder by utilizing the space in the side cam cylinder of the side cam system. As a result, the present invention can make the zoom lens device more compact than the conventional zoom lens device in which the drive motor is attached to the side of the side cam barrel.

Further, by mounting the zoom information detecting means in the gap between the drive motor inserted into the side cam barrel and the side cam barrel, the zoom lens device can be made more compact.

[0008]

The preferred embodiments of the zoom lens device according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an embodiment of a zoom lens device 10 according to the present invention.
The zoom lens device 10 includes three moving lens groups 12, 1
This is a side-cam type zoom lens device in which side-cam barrels 18 are arranged on the sides of Nos. 4 and 16. Moving lens group 1
2, 14, and 16 are lens frames 20, 22, and 24, respectively.
Are held in the lens frame bodies 20, 22, 2
4 has three guide poles 26, 28 (one not shown)
It is slidably supported by. The guide pole 2
The left end portions of the reference numerals 6 and 28 are fixed to the frame body 32 of the front lens 30, and the right end portions thereof are fixed to the frame body 36 of the master lens 34. The frame 32 of the front lens 30 is fixed to a support plate 38 (not shown) on the camera body side with bolts 40, 40, and the master lens 34 is used.
The frame 36 is fixed to the support plate 38 by bolts 42, 42, 42. As a result, the movable lens groups 12, 14, 16, the front lens 30, and the master lens 34 are supported by the support plate 38.

A support base 44 is attached to the side cam barrel 18, and the support base 44 is fixed to the support plate 38. Further, cam grooves 46, 47, 48 are formed on the peripheral surface of the side cam cylinder 18. These cam grooves 46, 47, 48 are provided with the side cam barrel 18 at a predetermined position so that the lens frame bodies 20, 22, 24 are formed.
The cam pins 50 and 52 (one of which is not shown) which are planted in the above are respectively fitted. Therefore, by rotating the side cam barrel 18, the lens frame bodies 20, 22, and 24 can be relatively moved back and forth in the optical axis direction with a predetermined relationship.

As shown in FIG. 2, a drive motor 54 for rotating the side cam barrel 18 is inserted and disposed in the side cam barrel 18 via a base 56 and a fixing spring 58 which will be described later. A speed reduction mechanism 60 is connected to the drive motor 54. The final gear 62 of the reduction mechanism 60 is the drive motor 5
When 4 is inserted and arranged in the side cam cylinder 18 together with the base 56, it is meshed with the internal gear 64 projecting from the notch 57 of the base 56 and screwed on the inner peripheral surface 18a of the right end portion of the side cam cylinder 18. Further, the cam guide surface 56a of the base 56 has an inner peripheral surface 18b on the right end of the side cam barrel 18.
Are slid on. As a result, when the drive motor 54 is driven, the side cam barrel 18 can be rotated via the speed reduction mechanism 60.

The base 56 is formed in a tubular shape so that the drive motor 54 can be inserted and arranged therein. Also,
The drive motor 54 inserted in the base 56 is fixed to the base 56 with bolts 59. The base 56
A rectangular notch groove 66 is formed in the axial direction of the outer peripheral surface of
A zoom resistance plate 68, which is a zoom position detecting means, is fixed to the notch groove 66. A conductive brush 72 fixed to the edge of the follower 70 is brought into contact with the zoom resistance plate 68. This follower 70 has a pin 7 that is planted on its upper surface.
4 is fitted into the long hole 76 formed in the fixing spring 58 described above, and in that state, the fixing spring 58 is fitted into the outer peripheral surface of the base 56, so that the brush 72 causes the zoom resistance plate 6 to move.
It is fixed in the state of being in contact with 8. Further, the tip of the pin 74 fitted in the long hole 76 has the fixing spring 58 on the base 56.
By inserting and arranging the side cam barrel 18 in the side cam barrel 18, the cam groove 46 of the side cam barrel 18 is fitted.

As a result, in the follower 70, the cam groove 46 and the long hole 76 are formed when the side cam barrel 18 rotates.
It is possible to slide on the zoom resistance plate 68 by being guided by. The resistance value of the zoom resistance plate 68 changes as the brush 72 slides on the zoom resistance plate 68, and this resistance value is output from the zoom resistance plate 68 to a CPU (not shown). The CPU detects the zoom position of the moving lens groups 12 and 14 based on the resistance value.

Further, both ends of the side cam barrel 18 are supported by the above-mentioned support base 44. That is, the shaft 80 of the base 56 inserted and arranged in the side cam cylinder 18 is supported by the horseshoe-shaped groove 82 formed by bending on the left side of the support base 44, and the reduction mechanism 6 inserted and arranged in the side cam cylinder 18 is disposed.
0 is fixed to the disc-shaped member 84 bent and formed on the right side of the support base 44 via bolts 86, 86. As a result, the side cam barrel 18 is supported by the support base 44.

Next, the operation of the zoom lens device 10 configured as described above will be described. When the drive motor 54 inserted in the side cam barrel 18 is operated by a drive signal from a CPU (not shown), the driving force of the drive motor 54 is transmitted to the side cam barrel 18 via the speed reduction mechanism 60, so that the side cam barrel 18 moves. Rotate. When the side cam barrel 18 rotates, the moving lens groups 12, 14, 1
6 relatively moves back and forth in the optical axis direction along the cam grooves 46, 47, 48 of the side cam barrel 18. As a result, the focal length of the moving lens groups 12 and 14 changes.

Further, as the side cam barrel 18 rotates, the follower 74 shown in FIG. 2 slides on the zoom resistance plate 68, and the resistance value changed by this is output to the CPU. As described above, in this embodiment, since the drive motor 54 and the reduction mechanism 60 are inserted and arranged in the side cam barrel 18, the zoom lens is larger than that of the conventional zoom lens device in which the drive motor is arranged on the side of the side cam barrel. The device can be made compact.

Further, since the zoom resistance plate 68 and the follower 70 are arranged between the drive motor 54 inserted in the side cam barrel 18 and the side cam barrel 18, the zoom lens apparatus can be made more compact. Further, by unitizing the side cam cylinder 18 in which the drive motor 54, the zoom resistance plate 68 and the follower 70 are inserted and arranged, the zoom lens device 10 can be easily assembled in a short time.

In this embodiment, the pin 74 of the follower 70 is used.
The cam pin 50 and the cam pin 50 are respectively fitted in the cam grooves 46 of the side cam cylinders 18, but the present invention is not limited to this.
You may make it fit in the same position of 6.

[0018]

As described above, according to the zoom lens device of the present invention, since the drive motor for driving the side cam barrel is inserted in the side cam barrel of the side cam system, the zoom lens device can be made compact. Further, since the zoom information detection means is attached to the gap between the drive motor inserted into the side cam barrel and the side cam barrel, the zoom lens device can be made more compact.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a zoom lens device according to the present invention.

FIG. 2 is an assembly view showing an embodiment of a side cam barrel applied to a zoom lens device according to the present invention.

[Explanation of symbols]

 10 ... Zoom lens device 12, 14, 16 ... Moving lens group 18 ... Side cam barrel 54 ... Drive motor 56 ... Base 58 ... Fixing spring 60 ... Reduction mechanism 68 ... Zoom resistance plate 70 ... Follower 72 ... Brush

Claims (2)

[Claims] 1. A plurality of lens frame bodies to which a plurality of movable lens groups are attached, a plurality of support rods for supporting the plurality of lens frame bodies, and each lens frame body arranged on the side of the plurality of lens frame bodies. A side cam cylinder in which each pin formed in each of the pins is fitted in each groove, and a drive motor for rotating the side cam cylinder to move the plurality of lens frame bodies back and forth in the optical axis direction along the cam groove. In the zoom lens device including the zoom lens device, the drive motor is inserted and arranged in the side cam barrel. 2. The zoom lens apparatus according to claim 1, wherein zoom information detecting means is attached to a gap between the drive motor inserted into the side cam barrel and the side cam barrel.