JPS59229504A - Lens moving device - Google Patents

Abstract

PURPOSE:To enable realization of a small-sized and inexpensive video camera with simple constitution by constituting with the 1st and 2nd lens holding frames movable toward the optical axis are moved toward the optical axis by the two cam grooves of a flat plate cam. CONSTITUTION:When a zoom motor 29 runs, a driving wheel is rotated counterclockwise by a gear 31 fixed to a motor shaft and an idler gear 32. A cam plate 23 is turned in the direction intersecting orthogonally with the optical axis by the pin of the driving wheel engaged with the perforation of a cam plate 23 and the 1st and 2nd lens holding frames 28 embedded with cam followers 41, 42 engaging with cam grooves 25, 26 are moved toward the optical axis while regulated by the grooves 25, 26, by which the zooming operation is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a lens moving device that is effective for use in video cameras and the like.

Conventional Structure and Problems The conventional zooming mechanism for a lens barrel generally uses a cam barrel attached to a fixed barrel to move the lens. This will be explained with reference to FIG. Figure 1 is a partial sectional view of the main parts of a conventional example of a zoom lens mirror, in which 1 is a fixed barrel, 2 is a focus ring,
A helicoid screw 2a provided on the focus ring 2 is screwed into a helicoid screw 1a provided on the fixed barrel 1,
By rotating along the optical axis, the focusing lens L1. L2
゜La is edged out in the optical axis direction. Ll, L2. La is suppressed and fixed by a lens holder 3 and a spacer 4. The second lenses L4, Lcs, and La are inserted into the first lens holding frame 8, and the screw portion 9& of the presser foot 9 of the second lens L4 is screwed into the screw portion 8B of the first lens holding frame 8. As a result, it is fixed to the first lens holding frame 8. The third lens L7 is inserted into the second lens holding frame 10, and is fixed by being pressed by the presser ring 11 of the third lens L7. 5 is a first lens holding frame 8 and a second lens holding frame 1o
This is a cam cylinder provided with a first cam groove 14 and a second cam groove 16 that move in the optical axis direction using the pawl 6.7 as a guide, and its position is regulated by a pawl support plate 47.

In the first cam groove 14 and the second cam groove 16, a first lens holding frame 8 and a third lens are provided in order to regulate the positions of the second lenses L4, L5, L6 and the third lens L7 on the optical axis, respectively. The pins 12 and 13 of the two-lens holding frame 1o are engaged with each other, and a pin 16 is implanted in the cam cylinder 6, passing through an elongated hole 17 and protruding to the outside of the fixed IF 11. 1
8 is a zoom ring having a legitimate child 2o, and a zoom gear 21
is fitted so as to be rotatable around the optical axis, and a pin 16 is engaged with a long groove 19 formed on the inner peripheral side. That is, when the zoom ring 18 is rotated, the pin 16 engaged with the long groove 19 is driven and the cam cylinder 5 is rotated, so that the first
The positions of the second lenses L4, L5, L6 and the third lens L7 in the lens holding frame 8 and the second lens holding frame 1o are regulated by the first cam groove 14 and the second cam groove 16, so that zooming is not possible. It will be done. However, in a configuration in which the lens is moved using a cam attached to a fixed cylinder as described above, it is necessary to cover the lens movement frame with at least three layers: a cam cylinder, a fixed cylinder, and an operation ring. There is.

Furthermore, in the cam cylinder and fixed cylinder, extremely high positional accuracy is required for each movable lens group, so highly accurate machining of the positioning stop of each movable lens group is essential. Therefore, there is a certain limit to the reduction in the number of parts, and the processing costs associated with high-precision processing are also high. In fact, it is impossible to eliminate deformation and distortion of the cylinder due to cam groove machining in a cam cylinder formed by a cam groove obtained by penetrating the inside of the cylinder. In order to reduce the deformation of the cam cylinder, the rotation angle of the cam groove cannot be made large.

If the rotation angle of the cam groove is small, the curve of the cam becomes tight, which tends to cause uneven operation, and since the amount of advance of the cam relative to the rotation angle is large, even a small error has a large effect.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a lens moving device that simplifies the configuration by introducing a flat cam mechanism for lens movement, thereby making it possible to realize a compact and inexpensive video camera.

Structure of the Invention In order to achieve the above object, the lens moving device of the present invention includes a first lens holding frame and a second lens holding frame that are movable in the optical axis direction, and a mechanism for driving the first lens holding frame. and a second cam for driving the first lens holding frame and the second lens holding frame, and by moving these cams in a direction perpendicular to the optical axis, the first lens holding frame and the second lens holding frame are moved. The second holding frame is configured to move in the optical axis direction.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a perspective view of a main part of a lens barrel in an embodiment of the present invention, and FIG. 3 is a sectional view of the main part of FIG. 2. In FIGS. 2 and 3, 22 is a lens ffA, a second lens group B, a third lens group C9, a fixed lens D, and an aperture 3.
4. A lens substrate for performing focusing operations, zooming operations, and mounting the master lens group E in fixed positions, respectively. 37 is a second lens holding frame, 2
7 is a second lens holding frame, and 28 is a third lens holding frame. In the second lens holding frame 27, a guide pole 36 supported by the lens substrate 22 is inserted through the hole 27&, and a rotation prevention notch (not shown) is engaged with the guide pole 37 supported by the lens substrate 22. By doing so, the lens substrate 2
2 so as to be movable in the optical axis direction. Similarly, in the third lens holding frame 28, the guide pole 37 is inserted through the hole 28a, and the guide pole 36 has a rotation prevention notch 28.
By engaging b, it is supported movably on the lens substrate 22 in the optical axis direction.

23 is a first lens unit for moving the second lens group B in the optical axis direction.
This cam plate is provided with a cam groove 25 and a second cam groove 26 for moving the third lens group C in the optical axis direction, and is made of a flexible thin plate such as stainless steel or plastic. be. Reference numeral 29 denotes a zoom motor, and a motor mount is attached to a plate 30, and the output of the zoom motor 29 is transmitted from a motor gear 31 press-fitted into the motor shaft to an idler gear 32. Drive wheel 3 via transmission gear (not shown)
3. The pin 33' formed on the drive wheel 33 engages with the perforation 24 formed on the end surface of the cam plate 23, and thereby the cam plate 23 is moved in a direction perpendicular to the optical axis, and the second lens holding frame is moved. Then, the third lens holding frame moves in the optical axis direction. The lens substrate 2 is used to regulate the position and lifting of the cam plate 23 in the optical axis direction.
2, a regulator 6o is attached.

The first cam groove 25 of the cam plate 23 is provided with a second lens holding frame 2.
The first cam follower 41 implanted in 7 engages,
A second cam follower 42 implanted in the third lens holding frame 28 is engaged with the second cam groove 26 .

The operation of the lens moving device of this embodiment configured as described above will be described below.

In FIGS. 2 and 3, when the zoom motor rotates and the drive wheel 33 rotates counterclockwise, the cam plate 23 moves to the left. As a result, the second lens holding frame 27 and the second lens holding frame 28 are connected to the first cam groove 26. It moves in the optical axis direction while being regulated by the second cam groove 26 to perform a zooming operation.

As described above, according to this embodiment, by introducing a flat cam mechanism into the zooming mechanism of the lens barrel, compared to the conventional system in which the lens is moved using a cam barrel attached to a fixed barrel. It is possible to reduce the number of parts, and by using a flat plate cam, a simple and highly accurate cam can be manufactured, and a small and inexpensive video camera can be realized. In addition, in the above embodiment, a driving member in which the first cam groove and the second cam groove were integrated was explained, but it is also possible to configure the first cam groove and the second cam groove as separate parts, and to They may be joined by links.

Effects of the Invention As is clear from the above description, according to the present invention, a cam barrel is required in a conventional structure in which a lens is moved using a fixedly attached cam barrel.

There is no need for members that require highly accurate machining, such as a fixed cylinder and an operating ring, and by using, for example, a cam plate, it is possible to achieve a significant reduction in the number of parts. Furthermore, when a cam plate is used, it can be punched, making it highly suitable for mass production, and provides excellent effects such as being able to easily process with high precision. Furthermore, if a flexible cam plate is used, the range of movement of the cam plate can be reduced, and the width dimension of the camera can also be reduced. As a result, an excellent effect can be obtained in that a compact and inexpensive video camera with a simplified configuration can be realized.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side sectional view showing a conventional zoom lens barrel, Fig. 2 is a perspective view of a main part of a lens mirror according to an embodiment of the present invention, and Fig. 3 is an embodiment of the same invention. FIG. DESCRIPTION OF SYMBOLS 1...Fixed barrel, 2...Focus ring, 6...Cam tube, 18...Zoom operation ring, 22...River/lens board, 23 ...Cam plate, 25.26, mountain, cam groove, 27.28...
・Lens movement frame, 29...Zoom motor, 31
...Motor gear, 33. Mountain... Drive wheel, 36.
37...Guide ball, 41.42...
Cam follower, A... Focus lens group,
B...Second lens group, C...Mountain...Third lens group.

Claims (3)

[Claims] (1) A first lens holding frame and a second lens holding frame that can move in the optical axis direction, and a first cam that moves in a direction perpendicular to the optical axis that drives the first lens holding frame. and a second cam that moves in a direction perpendicular to the optical axis for driving the second lens holding frame. (2) The lens moving device according to claim 1, wherein the first cam and the second cam are formed from the same cam plate. (3) The lens moving device according to claim 3, wherein the cam plate is made of a flexible member.