JP2832930B2 - Lens moving device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a lens moving device in which a variator lens and a compensator lens are individually moved in the optical axis direction while being associated with each other to perform zooming, and in particular, to a small-sized lens moving device. And a lens moving device suitable for use in a video camera. SUMMARY OF THE INVENTION In the present invention, a cam is provided on a driving disk rotating in a plane parallel to a plane including an optical axis, and the cam directly drives a compensator lens, and is provided on the driving disk. The pin is engaged with an engagement groove formed in the holding frame of the variator lens, thereby moving the variator lens in the optical axis direction. The present invention relates to a lens moving device including an electric zoom lens unit adapted to be used. [Related Art] A zoom lens unit used for a video camera is
A variator lens and a compensator lens are arranged between the focusing lens and the master lens. Then, the variator lens and the compensator lens are separately moved in the optical axis direction while having an association therebetween, thereby performing a zooming operation.
In a conventional apparatus, the above-described zooming operation is performed by a cylindrical cam incorporated in a lens barrel. [Problems to be Solved by the Invention] According to such a conventional structure, a cylindrical cam having a diameter substantially equal to that of the focusing lens is required, and the zoom lens is small despite the small diameter of the variator lens and the compensator lens. There is a disadvantage that the outer diameter of the unit becomes large. Further, in the case of the electric zoom, there is no other choice but to attach a drive motor to the outside, and there is a disadvantage that the entire lens unit becomes very large. In view of such a drawback, for example, as disclosed in JP-A-59-104613, a fan-shaped drive plate that rotates in a plane parallel to the optical axis is provided, and provided on this drive plate. The two cams move the compensator lens and the variator lens in the optical axis direction. According to such a structure, in order to increase the moving stroke of the variator lens, the size of the driving plate must be increased, which hinders miniaturization. Further, since the two cams are provided on the same drive plate, interference between the two cams must be prevented, and there is a disadvantage that the degree of freedom is hindered. To perform the macro operation further, it is necessary to move only the compensator lens while keeping the variator lens stationary.
There is a disadvantage that it is very difficult to take such a structure. The present invention has been made in view of such a problem, and a lens moving device capable of making a zoom lens unit smaller, causing a variator lens and a compensator lens to perform desired movements, and performing a macro operation. The purpose is to provide. [Means for Solving the Problems] The present invention relates to a lens moving device in which a variator lens and a compensator lens are separately moved in the optical axis direction while being associated with each other to perform zooming. A cam is provided on a disk that rotates in a parallel plane and is driven by a driving unit. A cam follower provided on a holding frame that holds the compensator lens is engaged with the cam, and the disk rotates. An engaging groove extending in a direction approaching the optical axis on a plane parallel to the plane is provided in a holding frame holding the variator lens, and a pin implanted in the disc is engaged with the engaging groove. And a plane parallel to the plane on which the disk rotates so that an arc-shaped guide surface having the same curvature as the rotation locus of the pin is continuous with the end of the engagement groove. In the holding frame of the variator lens up to a position near the position corresponding to the optical axis, and during macro operation, the compensator lens is moved forward without moving the variator lens in the optical axis direction. Lens moving device. [Operation] Therefore, according to the present invention, it is only necessary to provide a cam for moving the compensator lens on the disk, and there is no interference with the cam for driving the variator lens. Therefore, it is possible to separately move the two lenses as desired. Further, the arc-shaped guide surface provided so as to be continuous with the end portion of the engagement groove of the holding frame of the variator lens makes it possible to advance the compensator lens without moving the variator lens in the optical axis direction, This enables a macro operation for close-up photography. [Embodiment] The optical system of a video camera will be described with reference to FIGS. 2 and 3. This optical system includes a focusing lens 10 at the front end thereof, and is supported by a holding frame 11. The holding frame 11 is supported by a frame 14 by a pair of guide rods 12,13. Moreover, one guide rod 12
An external thread 15 is formed on the outer peripheral surface of the
Are adapted to mesh with the internal threads of the sleeve 16. Further, a pulley 17 is fitted on the outer peripheral side of the sleeve 16. Frame behind the focusing lens 10
Above 14 is a variator lens 20 and a compensator lens 21
Is arranged. These lenses 20, 21 are supported by holding frames 22, 23, respectively. The holding frames 22, 23 are the first
As shown in the figure, the guide rods are supported by three guide rods 24, 25, 26. That is, the holding frame 22 that holds the variator lens 20 is supported by the guide rods 24 and 26. On the other hand, the holding frame 23 for holding the compensator lens 21 has a guide rod 25,
It is supported by 26. Next, a mechanism for moving the holding frames 22, 23 for holding the lenses 20, 21 will be described. A driving disk 30 is rotatably supported on the frame 14. And pin 31 on disk 30
And this pin 31 is a variator lens
An engagement groove 32 formed on the lower surface of the holding frame 22 for holding 20
To be engaged. The end of the engagement groove 32 is formed in an arcuate guide surface 33. A cam follower is provided on the lower surface of the holding frame 23 for holding the compensator lens 21.
The cam follower 34 is provided so as to be engaged with a cam 35 formed on the disk 30. A motor 36 is provided on the side of the frame 14 and a pulley 37 is provided on an output shaft thereof. The pulley 37 is transmitted by a pulley 38 and a belt 39.
And while the worm 40 is attached to the pulley 38,
The worm 40 meshes with the worm gear 41. A drive gear 42 is provided on the worm gear 41, and the drive gear 42 is designed to mesh with teeth formed on the outer peripheral surface of the disk 30. An aperture unit is located behind the compensator lens 21
45 are arranged. A lens barrel 46 is provided on the frame 14 on the rear side of the aperture unit 45, and a master lens 47 including a plurality of lenses is disposed in the lens barrel 46. A frame 48 is fixed to the rear end of the lens barrel 46, and a CCD 49 is held by the frame 48 (see FIG. 5). Next, the operation of the lens moving device having the above configuration, particularly the zooming operation, will be described. In the case of the wide operation for widening the angle of view, the pulley 37, the belt 39, the pulley 38, the worm 40, and the worm gear are driven by the motor 36.
The disc 30 is rotated counterclockwise in FIG. 6 by the drive gear 41 and the drive gear 42. Then the holding frame by the pin 31
The engagement groove 32 of 22 is pushed, and the variator lens 20 moves to the focusing lens 10 side. At the same time, the compensator lens 21 via the cam follower 34 by the cam 35 of the disc 30
Is moved to the CCD49 side. That is, in the case of the wide operation, the variator lens 20 and the compensator lens 21 are moved so as to be separated from each other. Next, in the case of the tele operation for narrowing the angle of view, as shown in FIGS. 8 and 9, the driving disk 30 is rotated clockwise, the holding frame 22 is moved backward by the pin 31, and the compensator is moved. The variator lens 20 is retracted to a position immediately before the lens 21. That is, both the variator lens 20 and the compensator lens 21 are moved to positions far from the focusing lens 10. Next, the micro operation for close-up photography will be described with reference to FIGS. 10 and 11. FIG. In this case, the disk 30 is further rotated in the counterclockwise direction than in the wide operation. Then, the pin 31 of the disk 30 is disengaged from the engagement groove 32 of the holding frame 22, and the pin 31 comes into contact with the arc-shaped guide surface 33 which is continuous with the engagement groove 32. At this time, the variator lens 20 is not moved in the optical axis direction because the arc-shaped guide surface 33 coincides with the rotation locus of the pin 31. In such a state, the end of the cam 35 on the driving disk 30 causes the compensator lens 21
Is slightly advanced to the focusing lens 10 side. In this manner, only the compensator lens 21 is moved while the variator lens 20 is stationary, and micro operation for close-up photography becomes possible. According to such a lens moving device, the compensator lens 21 is directly moved by the cam 35 formed on the disk 30 as described above, and the variator lens 20 is engaged with the pin 31 of the disk 30 and the holding frame 22. The groove 32 allows the movement in the axial direction. And two lenses
The holding frames 22, 23 of 20, 21 are guided movably in the optical axis direction by three guide rods 24-26. Therefore, the zoom lens unit does not require a lens barrel, and it is possible to arrange a driving means such as the disk driving motor 36 in a space obtained by omitting the lens barrel. This makes it possible to reduce the size of the optical system of the video camera, especially the size of the zoom lens unit. Further, the holding frame 11 of the focusing lens 10 is guided by two guide rods 12 and 13,
Focusing lens by screw 15 of guide rod 12
10 is moved in the axial direction to focus. Since the driving unit of the focusing lens 10 is also disposed in the extra space on the outer peripheral side of the zoom lens unit, the driving unit does not protrude beyond the outer peripheral side of the focusing lens 10. In this optical system, as shown in FIG. 4, the upper and lower portions on the outer peripheral side of the focusing lens 10 are cut to reduce the thickness in the height direction. Furthermore, since the fixing of the focusing lens 10 is achieved not by the ring nut but by the presser screws 52 planted in the four corners of the holding frame 11, the opening of the lens 10 can be enlarged. As a result, a sufficient opening area can be secured. With such a combination, as shown in FIGS. 2 to 5, all the mechanisms including the electric drive unit are housed within the outer diameter of the focusing lens 10 whose upper and lower parts are cut, and the whole is made compact. It becomes possible to do. In the structure of the present embodiment, the variator lens 20
Is moved by pushing the engaging groove 32 using the pin 31 of the disk 30. Therefore, even if the disc 30 rotates to a position where the radius passing through the pin 31 is parallel to the optical axis, a large load is not applied to the disc 30. By the way, a cam is provided on the disk,
When the variator lens is moved by the cam, a large lateral pressure is applied to the cam depending on the rotational position of the disk, and therefore, there is a disadvantage that the driving torque of the disk becomes extremely large. According to the structure of the present embodiment, such a drawback is eliminated, and the disk 30 is rotationally driven with a small torque, and the two lenses 20 and 21 are smoothly moved in the optical axis direction to perform an accurate zoom operation. It is possible to do. [Effects of the Invention] As described above, the present invention is provided on a holding frame that holds a compensator lens by providing a cam on a disk that rotates in a plane parallel to a plane including an optical axis and is driven by a driving unit. The cam follower is engaged with the cam, and an engaging groove extending in a direction approaching the optical axis on a plane parallel to the plane on which the disk rotates is provided on the holding frame holding the variator lens, and is implanted on the disk. The engaging pin is engaged with the engaging groove, and an arc-shaped guide surface having the same curvature as the rotation locus of the pin is parallel to the plane on which the disk rotates so as to be continuous with the end of the engaging groove. On the plane, the variator lens should be provided on the holding frame up to the vicinity of the position corresponding to the optical axis, and during macro operation, the compensator lens should be moved forward without moving the variator lens in the optical axis direction. It is a thing. Accordingly, desired movements can be given to the variator lens and the compensator lens, respectively, and the cam of the disk and the engaging groove of the holding frame of the variator lens do not interfere with each other. Further, the arc-shaped guide surface provided so as to be continuous with the end of the engagement groove of the holding frame of the variator lens makes it possible to advance the compensator lens without moving the variator lens in the optical axis direction. This enables macro operation for close-up photography. In addition, it is possible to reduce the driving torque of the disk for moving the variator lens and the compensator lens, respectively, whereby the size of the driving unit can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view of a main part of a zoom mechanism of an optical system of a video camera according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing the entire structure of the optical system, FIG. 3 is a bottom view of a drive unit of the zoom mechanism, FIG. 4 is a front view of an optical system showing a focusing lens, FIG. 5 is a rear view of an optical system showing a CCD, FIG. 7 is a sectional view of the same side, FIG. 8 is a plan view of the tele operation, FIG. 9 is a sectional view of the same side, FIG. 10 is a plan view of the micro operation, and FIG. 11 is a sectional view of the same side. In the reference numerals used in the drawings, 20 variator lens 21 compensator lenses 22 and 23 holding frame 30 drive disk 31 pin 32 engagement groove 33 arc-shaped guide surface 34 … Cam follower 35… It is a cam.

Continuation of the front page (56) References JP-A-52-60130 (JP, A) Jiko 49-12601 (JP, Y2) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 7 / 04 G02B 7/105

Claims (1)

(57) [Claims] In a lens moving device in which a variator lens and a compensator lens are separately moved in the optical axis direction while being related to each other to perform zooming, the lens moving device rotates in a plane parallel to a plane including the optical axis and is driven by driving means. A cam is provided on the disc, and a cam follower provided on a holding frame for holding the compensator lens is engaged with the cam, and in a direction approaching the optical axis on a plane parallel to a plane on which the disc rotates. An extending engagement groove is provided in a holding frame for holding the variator lens, a pin implanted in the disk is engaged with the engagement groove, and a circle having the same curvature as a rotation locus of the pin is provided. On a plane parallel to the plane on which the disk rotates so that the arcuate guide surface is continuous with the end of the engagement groove, the arc guide surface is located near a position corresponding to the optical axis. The so provided in the holding frame of the variator lens, when the macro operation lens moving device is characterized in that so as to advance the compensator lens without moving the variator lens in the optical axis direction.