JPS646497Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a lens extension mechanism for controlling the amount of extension of a photographing lens to a focused point in an autofocus camera.

In recent years, automatic focus cameras have been developed in which the photographing lens is extended to a fixed position while charging a spring in conjunction with the film winding operation, etc., and then retracted by the force of the spring in conjunction with the release operation. Cameras have been developed that are equipped with an autofocus (AF) mechanism in which the lens movement (lens extension amount) is stopped at the in-focus position by a focus signal from an automatic focus control device. Conventionally, as a control mechanism, there is a method in which a helicoid is formed in the lens block (lens barrel), and the helicoid is rotated and extended by a spring that follows the lens drive system. The conventional and time-consuming work of forming a helicoid on a block results in a relatively high cost, and it is difficult to control the friction, spring balance, and pin out of the helicoid part, etc. There was a problem.

Alternatively, instead of forming a helicoid on the lens block, the AF drive ring is provided with a feeding cam surface, and the lens block is brought into contact with this.
There are some systems that move the AF drive ring and extend the lens using the cam surface for extending it, but in conventional models, the lens block is used as a spring drive source due to its structure, and is brought into contact with the cam surface for advancing the AF drive ring. This method has drawbacks such as an increase in the number of parts and a complicated structure, such as requiring two or more springs in total, including the spring that contacts the ring and the spring that drives the AF drive ring.

The present invention was developed in view of the above-mentioned drawbacks of the conventional technology, and has no functional deterioration.
It is an object of the present invention to provide a lens extension mechanism for an autofocus camera with a new structure that reduces the number of parts, simplifies the structure, and reduces costs.The present invention will be described in detail below with reference to the drawings.

The drawing is an exploded perspective view of essential parts of a preferred embodiment of the lens extending mechanism of the autofocus camera according to the present invention.

In the figure, reference numeral 1 denotes a photographing lens, which is held in a lens block (lens barrel) 2. The lens block 2 has three boss portions 2a, 2 on its circumferential surface.
a, 2a (one location is not shown),
It has a latch gear 2b and a pin 2c, and has an engaging portion 2d on its end surface. Reference numeral 3 denotes a compression torsion coil spring having both compression and torsion properties, which is fixed on a fixed base plate 4 disposed behind the lens block 2, and which has multiple forces in the direction of arrow A and arrow B.
The hook portion 3a at the tip thereof is engaged with the engaging portion 2d of the lens block 2, and is connected (integrated) with the lens block 2.

5 is a lens feeding ring fixed in front of the lens block 2;
Feeding cam surfaces 5a, 5a, 5a are formed at equal intervals to correspond to and press against the three boss portions 2a, 2a, 2a, respectively. Reference numeral 6 denotes an AF drive rod that is controlled in conjunction with the AF drive system, and is in contact with the pin 2c of the lens block 2, and in conjunction with the film winding operation, moves the lens block 2 against the compression torsion coil spring 3. Also serves as a charge member to feed out the material to a fixed position.

Reference numeral 7 denotes a latch member that receives a focus signal from an AF control circuit (not shown) and enters (meshes with) the latch gear 2b of the lens block 2 to stop the lens block 2, and is located near the lens block 2. It is swingably installed on a fixed member (not shown).

Since the present invention has such a structure, first of all, the AF is performed in conjunction with the film winding operation, etc.
The drive rod 6 charges the rotational force of the lens block 2 and the compression torsion coil spring 3 integrated therewith in the direction of arrow B, and moves it leftward (moves) to a fixed position.

Next, when the release operation is performed, a distance information pulse is input from the AF block (not shown) of the distance measuring device to the AF control circuit (also not shown), and in response
When the AF drive rod 6 linked to the AF drive system moves, the lens block 2 is given rotational force by the compression torsion coil spring 3 and rotates from the fixed position in the retracting direction. 2a, 2
a is pushed to the right along the extending cam surfaces 5a, 5a, 5a of the lens extending ring 5, so that the lens block 2 is extended, but in the process, the focusing signal from the AF control circuit is In response to the signal, the latch member 7 operates and enters (meshes with) the latch gear 2b of the lens block 2 to stop the movement or retracting of the lens block 2, and the photographing lens 1 is held and fixed at a proper position. Thereafter, a shutter mechanism (not shown) is activated to take a picture, and the winding operation is performed again.

In the above embodiment, the lens extending ring is placed on the front side of the camera and the compression torsion coil spring is placed on the rear side of the lens block, but this order may be reversed. In that case, the slope of the feeding cam surface may be reversed.

As described above, the lens feeding mechanism of the automatic focus camera of the present invention has a simple structure and requires a small number of parts, so it can be expected to have a great effect in reducing costs. The structure is such that the feeding cam surface, which is formed with a balance between When doing so, there is also the advantage that it can be easily accomplished by simply rotating the lens feeding ring.

[Brief explanation of the drawing]

The drawing is an exploded perspective view of a main part of a preferred embodiment of the lens extending mechanism of the autofocus camera according to the present invention. 1... Photographing lens, 2... Lens block (lens barrel), 3... Compression torsional recoil spring, 4... Fixed base plate, 5... Lens extension ring, 5a... Extension cam surface, 6... AF drive rod, 7... Latch member .

Claims (1)

[Claims for Utility Model Registration] The lens block is rotated and moved in the direction of the optical axis in conjunction with the release operation of the camera, and the movement is stopped in the middle by a focusing signal from the automatic focus control device. In a camera configured to allow the camera to rotate, the camera includes: a feeding ring having a plurality of feeding cam portions formed with slopes in the direction of the optical axis; and a compression torsion coil spring having both compression and torsion characteristics, one end of which is fixed to the camera body. are arranged to sandwich the lens block in the optical axis direction, and the lens block is formed with a plurality of protrusions that abut the plurality of cam parts, and also has an engagement that engages with the other end of the spring. 1. A lens extending mechanism for an autofocus camera, characterized in that a joint is formed, and the spring allows the lens block to operate in a rotational direction and an axial direction.