JPH0363046B2 - - Google Patents

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 configuration and its problems The conventional lens barrel zooming mechanism is as follows:
Generally, the lens is moved using a cam barrel attached to a fixed barrel. This will be explained with reference to FIG. FIG. 1 is a partial sectional view of the main parts of a conventional zoom lens barrel. 1 is a fixed barrel, 2 is a focus ring, and the focus ring is attached to a helicoid screw 1a provided on the fixed barrel 1. The helicoid screws 2a provided in L2 are screwed together and rotated around the optical axis, so that the focusing lenses L1 and
Extend L2 and L3 in the optical axis direction. 2nd lens L
4, L5, and L6 are inserted into the first lens holding frame 8, and the threaded portion 9a of the presser foot 9 of the second lens L4 is screwed into the threaded portion 8a of the first lens holding frame 8. 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 cam cylinder provided with a first cam groove 14 and a second cam groove 15 for moving the first lens holding frame 8 and the second lens holding frame 10 in the optical axis direction; Therefore, the location is regulated. Second lenses L4, L5, and L are provided in the first cam groove 14 and the second cam groove 15, respectively.
6 and the third lens L7 on the optical axis, the pins 12 and 13 of the first lens holding frame 8 and the second lens holding frame 10 are engaged, and the cam cylinder 5 is A pin 16 is implanted.
Reference numeral 18 denotes a zoom ring, into which 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 circumferential side.
That is, when the zoom ring 18 is rotated, the long groove 1
9 is driven and the cam cylinder 5 is rotated, the second lenses L4, L5, L in the first lens holding frame 8 and the second lens holding frame 10 are driven.
6 and the third lens L7 are located in the first cam groove 14.
Zooming is performed under the control of the second cam groove 15.

However, in the configuration in which the lens is moved using a cam attached to a fixed barrel as described above, it is necessary to configure at least a triple barrel of a cam barrel, a fixed barrel, and an operation ring to cover the lens moving frame. has become complicated. Furthermore, there was a drawback that the machining costs associated with high-precision machining of the cam cylinder were high. Further, a cam cylinder having a cam groove obtained by penetrating the flesh portion of the cylinder is likely to be deformed and strained due to the cam groove machining. In order to reduce the deformation of the cam barrel, the amount of advancement of the cam is increased with a small rotation angle of the cam barrel, which poses problems in the positioning of the movable lens group and the operational feel.

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 planar cam mechanism for lens movement, 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 first lens holding frame and a second lens holding frame that are movable in the optical axis direction. a guide member for guiding movement in the optical axis direction; a substrate for supporting the guide member; and between the substrate for driving the first lens holding frame and the first and second lens holding frames. a first cam interposed between the substrate and the first and second lens holding frames for driving the second lens holding frame; and a second cam that rotates in a plane parallel to the substrate, and by rotating these cams, the first and second lens holding frames are moved in the optical axis direction. It is composed of

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows a perspective view of essential parts of a lens barrel in an embodiment of the present invention. In FIG. 2, the lens substrate 22 includes a first lens group A, a second lens group B, a third lens group C, a fixed lens D, and an aperture 3.
4. A member for holding each master lens group (not shown) in a fixed position.

44 is a first lens holding frame that holds the first lens group A, 27 is a second lens holding frame that holds the second lens group B, and 28 is a third lens holding frame that holds the third lens group C.
A lens holding frame 39 is a fixed lens frame that holds the fixed lens D. A flat cam plate 23, a second lens holding frame 27, and a third
A lens holding frame 28 is arranged, and a flat cam plate 23, a second lens holding frame 27, and a third lens holding frame 28 are arranged.
The distance between the two is also kept small. In the second lens holding frame 27, a guide pole 36 supported by the lens substrate 22 is inserted through the hole 27a, and a rotation prevention notch (not shown) is engaged with the guide pole 37 supported by the lens substrate 22. By doing so, it is supported on the lens substrate 22 so as to be movable in the optical axis direction. Similarly, the guide pole 37 of the third lens holding frame 28 is inserted through the hole 28a, and by engaging the rotation prevention notch 28b with the guide pole 36, the third lens holding frame 28 can be moved in the optical axis direction on the lens substrate 22. Supported.

The planar cam plate 23 has a first cam groove 25 and a third cam groove for moving the second lens holding frame 27 in the optical axis direction.
A second cam groove 26 is provided for moving the lens holding frame 28 in the optical axis direction, and is rotatably mounted on a shaft (not shown) implanted in the lens substrate 22. A zoom motor 29 is attached to a motor mounting plate 30, and the output of the zoom motor 29 is transmitted from a motor gear 31 press-fitted into the motor shaft 29a, to an idler gear 32, to a crown gear (not shown), and then to a drive gear 33. and a gear 24 formed on the end surface of the planar cam plate 23.
It will be transmitted to As a result, the planar cam plate 23 is rotated, and the second lens holding frame and the third lens holding frame are moved in the optical axis direction.

Since the second lens holding frame and the third lens holding frame are exposed on the lens substrate in this way, the structure is simple and easy to assemble, and the second and third lens groups are easy to clean. Can be done.

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

Figure 3 shows the planar cam plate and the second
FIG. 4 is a plan view showing the relationship between the lens holding frame and the third lens holding frame. FIG. 4 is a plan view showing the relationship between the planar cam plate, the second lens holding frame, and the third lens holding frame in the telephoto state. In the second lens holding frame 27, a guide pole 36 supported by the lens substrate is inserted through the hole 27a, and a rotation prevention notch (not shown) is engaged with the guide pole 37 supported by the lens substrate 22. In particular, it is supported so as to be movable in the direction of the optical axis. Similarly, the third lens holding frame 28 guide pole 37 is inserted into the hole 28a, and is supported movably in the optical axis direction by engaging the rotation prevention notch (not shown) with the guide pole 36. ing. In the first cam groove 25 of the planar cam plate 23,
A first cam follower 41 implanted in the second lens holding frame 27 is engaged, and a second cam follower 42 implanted in the third lens holding frame 28 is engaged with the second cam groove 26. There is.

In FIG. 3, when the output of the zoom motor is transmitted from the drive gear 33 to the gear 24 provided on the end surface of the planar cam plate, the planar cam plate 23 rotates in the direction of an arrow 43 about a shaft 40. . As a result, the first lens holding frame 27 and the second lens holding frame 28
are the first cam groove 25 and the second cam groove 2, respectively.
6, performs a zooming operation and moves to the tele position shown in FIG.

As described above, according to the present embodiment, by introducing a planar cam mechanism into the zooming mechanism of the lens barrel, the structure is better compared to the conventional one in which the lens is moved using a cam barrel attached to a fixed barrel. It is simple and can be easily assembled. Furthermore, by using a planar cam, a high-precision cam can be easily manufactured by molding, and an inexpensive video camera can be realized.

Furthermore, since the planar cam plate is placed between the lens substrate and the second and third lens holding frames that move in the optical axis direction, the distance between the planar cam plate and the second and third lens holding frames is reduced. can be minimized, and the amount of protrusion of the cam follower can be small. Therefore, the rotational movement of the planar cam plate can be smoothly and accurately transmitted to the reciprocating movement of the lens holding frame in the optical axis direction.

Further, a gear is formed on the end face of the planar cam plate, and by driving this gear, the planar cam plate can be driven with a small torque. Furthermore, since the drive gear train is configured to be planar with respect to the planar cam plate, the thickness can be reduced.

In addition, the first lens holding frame, fixed lens frame, and master lens barrel that holds the master lens group are attached directly to the lens substrate, and the rotation center of the flat cam plate is provided, making it easy to see the relative positional relationship of the lenses. be.

In addition, in the above embodiment, a planar cam in which the first cam groove and the second cam groove were integrated was explained, but the first cam groove
The cam groove and the second cam groove may be formed as separate members, and these may be connected by a link or the like.

Effects of the Invention As is clear from the above description, according to the present invention, since the second lens holding frame and the third lens holding frame are exposed on the lens substrate, the structure is simple and assembly is easy. Furthermore, the second lens group and the third lens group can be easily cleaned. Furthermore, since a planar cam is used, the cam can be manufactured with high precision and high productivity through molding, etc., resulting in low cost.
Furthermore, since the planar cam plate is installed between the lens substrate and the second lens holding frame and the third lens holding frame, the distance between the planar cam plate and the second lens holding frame and the third lens holding frame can be minimized. The amount of protrusion can be small. Therefore, the rotational movement of the planar cam plate can be smoothly and accurately transmitted to the reciprocating movement of the lens holding frame in the optical axis direction. Further, a gear is formed on the end face of the planar cam plate, and by driving this gear, the planar cam plate can be driven with a small torque. Furthermore, since the drive gear train is configured to be planar with respect to the planar cam plate, it is possible to reduce the thickness dimension.

In addition, the first lens holding frame, fixed lens frame, and master lens barrel that holds the master lens group are attached directly to the lens substrate, and the rotation center of the flat cam plate is provided, making it easy to see the relative positional relationship of the lenses. Excellent effects such as:

[Brief explanation of drawings]

FIG. 1 is a partially cutaway side sectional view showing a conventional zoom lens barrel, FIG. 2 is a perspective view of essential parts of a lens barrel according to an embodiment of the present invention, and FIGS. 3 and 4 are the same according to the present invention. FIG. 3 is a plan view of main parts in the embodiment. 1...Fixed body, 2...Focus ring, 5...
...Cam tube, 18...Zoom operation ring, 22...Lens substrate, 23...Planar cam plate, 25, 26...Cam groove, 27, 28...Lens movement frame, 29...Zoom motor, 31... Motor gear, 33... Drive gear, 36, 37... Guide pole, 41, 42
...Cam follower, A...focus lens group, B...second lens group, C...third lens group.

Claims (1)

[Claims] 1 first and second lens holding frames movable in the optical axis direction, two guide poles that hold the first and second lens holding frames movably on the optical axis, and the first and second lens holding frames movable on the optical axis. first and second cams for directly driving the second lens holding frame;
and a second cam are formed, and the first cam is formed.
and a flat sector gear disposed adjacent to the second lens holding frame and rotating in a plane parallel to the optical axis; A lens moving device comprising: a substrate rotatably supported on the side; and a pinion provided on the same plane as the sector gear for driving the sector gear.