JPS5994708A - Zoom lens moving device - Google Patents

Abstract

PURPOSE:To simplify the control means for a driving source and a lens moving mechanism in constitution by mounting the driving source on a lens system holding base and moving the whole lens system, and moving part of the lens system by the same driving source through cam transmission. CONSTITUTION:The whole lens system 2 is moved in an optical-axis direction and the gap between some lenses of the lens system 2 is varied to perform magnification conversion; and the lens system holding base 3 which holds the whole lens system 2 and guides the lens system 2 movably in the optical-axis direction is provided. Further, a motor 12 which is fitted to this holding base 3 to drive the holding base 3 through a movement transmitting means and a transmitting means which is driven by the motor 12 to vary the lens gap between some lenses of the lens system 2 are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a zoom lens moving device, in particular, a zoom lens moving device that moves the entire lens system along the optical axis and moves the lens at the same time in order to change the magnification while keeping the distance between the object plane and the image plane constant. The present invention relates to a zoom lens moving device A configured to be able to displace the distance between some lenses of the system.

Conventionally, this type of zoom lens moving device has been designed with separate drive sources for moving the entire lens system in the optical axis direction and for displacing the distance between some lenses in the lens system. A device is known that is configured to control each of the circumferential drive sources.

However, such conventional devices not only have the disadvantage that the drive source and control system each require separate parts, which increases the number of parts required, leading to an increase in the number of parts, but also reduces the amount of movement of the entire lens system. This method has disadvantages in that it is difficult to make adjustments to correspond accurately to the displacement amount of the lens interval and to set the initial positions of the lenses with good reproducibility.

In addition, in another conventional zoom lens device, a lens holder that holds the entire lens system can be moved along a guide member by a separately fixed drive source, and this movement allows the lens system 9 to be moved around the lens system 9. A cylindrical cam is rotatable and guided via an abutment pin to a plate cam fixed along a guide member. Displace the I nonce interval by 1; ↑
There are also known devices configured to do so.

However, in such a conventional device, it is necessary to provide two cams that require high processing accuracy, which complicates the configuration of one member, and it is also necessary to adjust the two cams at the same time to set the initial position of the lens system. There was a drawback that it was not easy to use. Additionally, in this device, the cams are multi-stage, resulting in large power losses (therefore, it was necessary to provide a large power drive source).

The present invention was made in order to eliminate the drawbacks of such conventional devices, and [! It is an object of the present invention to provide a zoom lens moving device that reduces the number of parts by using one l1lJ source and one cam, and can accurately and easily adjust the position of a lens system.

Embodiments of the present invention will be described below based on the drawings.

In the figure, the symbol l is a lens barrel that holds the lens system 2,
This lens barrel 1 has a front bracket 1-3A and a rear bracket 3.
A is fixed to an optical bench 3 with B.

A cylindrical cam 4 constituting a cam transmission means is rotatably inserted into the outer periphery of the lens barrel l so as to be sandwiched between the brackets 1-3A and 3B. The cylindrical cam 4 is composed of a rotatable cylindrical portion 5 having a pair of curved grooves 5a, 5b formed in opposite directions on its surface, and pins 6a, 6b that engage with the respective grooves. An annular gear 7 is provided at one end of the cylindrical portion 5, and pins 6a and 6b are provided.
Movable lenses (not shown) constituting a part of the lens system are connected to Jb and Jb, respectively, and these movable lenses can freely move forward and backward within the lens barrel 1 only along the optical axis.

In addition, there are insertion holes 2b in the protruding parts 3a formed on both sides of each bracket 1, :'IA, 311. f
Shirts 1-8, each serving as a guide member, are arranged in parallel so as to pass through the insertion holes 3b of the overhanging portions 3a which are formed in the front and back on both sides. Both ends of the shirt 1-8 are fixed to a fixed frame 1z9, and this fixed frame 9
A rack 10 is mounted parallel to both shafts 8.

On the other hand, an L-shaped bearing plate 11 is provided on the overhang 3a on one side (right side in the figure) of each bracket l-3.
are fixed, and a motor 12 as a drive source is supported between these bearing plates 11. A driving gear 3 is attached to one end of the shaft of this motor 12, and this driving gear 13 is attached to the cylindrical portion 5 of the cylindrical cam 4 mentioned above.
The ring gear 7 meshes with the ring gear 7 shown in FIG. Further, a worm 14 constituting a movement transmission means is attached to the other end of the shaft of the motor 12, and this worm 14 meshes with a worm gear 15. The shaft J7 of the worm gear 15 is connected to the support plate 1 extending from the bracket h3IJll.
7, and a pinion 18 that engages with the rack 1 is attached to the end thereof.

A limit switch 19 electrically connected to the motor 12 is mounted on one of the brackets 3, and the limit switch 19 and the ring protruding from the annular gear 7 are connected to each other.
- The collar pin 20 can come into contact with the cylindrical cam 4.
The times! The FIl setting position can be regulated.

Further, the rotation of the motor 12 is controlled by a control means such as a switch (not shown).

Since the subject device is configured in this way, the motor 1
When you rotate the worm 14, the rotation 18
rotates, and an optical bench having brackets 1-3A and 313 and holding the lens system is guided by the shirts 1-7 and moves along the optical axis of the lens system. At the same time, the rotation of the motor 12 causes the annular gear 7 to rotate via the drive gear 13, causing the bins 6a, 6b of the cylindrical force is4 to move along the groove Jam 5b. Therefore, the lens system as a whole moves in the optical axis direction, and also displaces the lens interval of a part of it.
I start to feel noisy. In addition, by stopping the cylindrical portion 5 at a predetermined rotational position using the stopper pin 20 and the limiter 1-stopper 19 provided on the annular gear 7 integrated with the cylindrical portion 5, the movable lens can be stopped at a predetermined movement position with high precision. can. In this embodiment, the motor is stopped and controlled by a switch, but the motor is provided with a rotation angle detection means such as an encoder, and the rotation angle of the motor is controlled by a signal from the rotation angle detection means. You may.

In this way, the entire lens thread and the movable lens of the part thereof are moved in the optical axis direction while keeping the distance between the object plane located in front of the lens system 2 and the image plane located behind it constant. This makes it possible to freely change the magnification conversion and achieve t:J.

Hereinafter, as described in 1-1, according to the present invention, 13 drive sources are mounted on the lens system holding stand to move the entire lens system, and a part of the lens system is driven by the same drive source. Since the lens is moved by the transmission means, it is possible to realize a 1-down system in which the driving source control means and the lens moving mechanism are simple in structure. In addition, machining accuracy is required.
Since only one cam is required, manufacturing efficiency is improved. Furthermore, since the amount of movement of the entire lens system and the amount of movement of a portion of the lens system are always in a constant relationship, it is extremely easy to set the initial position or adjust the position of the lens system.

[Brief explanation of the drawing]

The figure is a perspective view illustrating an embodiment of a zoom lens moving device according to the present invention. 2... Lens system, 3... Optical bench (lens system holding stand)
, 4... Cylindrical cam (cam transmission means), 12... Motor (1 drive source).

Claims (3)

[Claims] (1) Move the entire lens system in the optical axis direction,
and a zoom lens device that performs magnification conversion by displacing a part of the lens interval of the lens system, a lens that holds the entire lens system and is guided movably in the optical axis direction of the lens system. A drive source that picks up the lens system holder and drives the lens system holder via a movement transmission means, and a distance between the lenses of a part of the lens system driven by the drive source. 1. A zoom lens moving device comprising a transmission means for changing the zoom lens. (2) Claims characterized in that the movement transmission means is comprised of a pinion connected to a drive source and a rack that meshes with the pinion and is disposed at 7r+ in the optical axis direction of the lens system. The zoom lens moving device according to item 1. (3) The cam transmission means has a cylindrical part on the outer periphery of the lens system that is concentric with the optical axis of the lens system and is rotatable by a drive source, and has a groove formed on the surface of the cylindrical part. 3. The zoom lens moving device according to claim 1, wherein the zoom lens moving device is constituted by a cylindrical cam having a pin that engages and connects with a part of the lens system.