JPH0570135B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to an improvement of a photographic lens driving device in an autofocus camera.

"Prior art and its problems" Conventionally, in an autofocus camera, a lens drive ring for rotating the movable lens barrel (taking lens), which is screwed onto a fixed barrel, is provided on the outside of the movable lens barrel (taking lens). Rotate the drive ring in either direction, depending on the subject distance.
The rotation angle of the lens drive ring is controlled against this spring means. The return of the movable lens barrel to its initial position is generally performed in conjunction with shutter charging.

However, this conventional device requires a device to detect the lens position (such as a code plate), a device to gradually move the lens (such as a governor), and a latch that locks the lens when it reaches a position that matches the subject distance. Since a mechanism, etc. is required, the number of mechanical parts increases, leading to a complicated mechanism, which also causes an increase in costs.

OBJECTS OF THE INVENTION It is an object of the present invention to solve the above-mentioned conventional problems and to provide a lens driving device that can drive and stop a photographic lens using a simple mechanism.

"Summary of the Invention" The present invention includes a movable lens barrel that is movable in the optical axis direction, a rotation center around the optical axis of the movable lens barrel, and a movable lens barrel that moves in the optical axis direction as the movable lens barrel rotates. An autofocus camera comprising: a lens drive ring that moves the lens drive ring; and ring biasing means that rotates the lens drive ring in either direction, and controls the rotational position of the lens drive ring according to a subject distance. A processing position return device is provided for rotating the lens drive ring to the initial position against the ring biasing means, and a ratchet in the circumferential direction is formed on the lens drive ring, and a ratchet is formed on the outer side of the lens drive ring. A locking member having a pair of pawls, one of which selectively engages with the ratchet to prevent rotation of the lens driving ring by the ring biasing means, is pivotally mounted on the locking member; an electromagnetic actuator that swings the locking member and alternately engages the pair of locking claws with the ratchet to allow rotation of the lens drive ring by the ring biasing means in stages; It has the following characteristics.

"Embodiments of the Invention" Examples of the present invention will be described in detail below with reference to the drawings.

1 and 2 show a first embodiment of the invention. A fixed lens barrel 13 that supports a movable lens barrel (taking lens) 12 is fixed to the main plate 11 . A female helicoid 13a is cut into the inner circumference of the fixed lens barrel 13, and a female helicoid 13a is cut into the inner circumference of the fixed lens barrel 13.
The male helicoid portions 14 are screwed together. Therefore, the movable lens barrel 12 moves in the optical axis direction as it rotates, and its focal position changes.

In order to rotate the movable lens barrel 12, a lens driving ring 15 is rotatably fitted around the outer periphery of the fixed lens barrel 13. This lens drive ring 15 has an interlocking pin 17 that protrudes toward the movable lens barrel 12.
is inserted into an interlocking hole 19 formed in the flange 18 of the movable lens barrel 12 . Therefore,
The movable lens barrel 12 is constantly connected to the lens drive ring 1
Make a rotation equal to 5. This lens drive ring 1
5 is rotationally biased in one direction by a tension spring 16 as a ring biasing means, and when no force is applied to the ring 15, the movable lens barrel 12 moves to the shortest photographing position or the infinite photographing position. do. Note that this lens drive ring 15 and movable lens barrel 12
For example, while supporting the movable lens barrel 12 so that it can move only linearly in the optical axis direction, the lens driving ring 15 is formed with a cam surface that engages with the movable lens barrel 12, and the ring 15 is The movable lens barrel 12 may be moved in the optical axis direction along with the rotation.

This lens drive ring 15 has, on its outer periphery,
Circumferential latches 20, 21 are formed. The ratchets 20 and 21 are connected to a pair of locking pawls 22a and 22 of a locking lever 22 as a locking member.
Although it is divided corresponding to b, it may be formed continuously.

The locking lever 22 is pivotally mounted on the outside of the lens drive ring 15 by a pivot shaft 23, and one of the locking claws 22a is rotated in a direction to engage the latch 20 by a spring 24 as a locking member biasing means. It is dynamically energized. A pair of locking claws 22a, 22
b is such that one of them selectively engages with the ratchets 20 and 21, and both do not engage with the ratchets at the same time. And this ratchet 2
0 and 21 and the locking claws 22a and 22b are provided in a direction that resists the force of the spring 16 and prevents rotation of the lens drive ring 15 when engaged.

In order to swing the locking lever 22 against the force of the spring 24, the locking lever 22 is equipped with a solenoid 2.
5 is connected. This solenoid 25 has a plunger 26 that normally advances and retreats when a drive pulse is applied.
A pin hole 27 into which a pin 28 set on the lock lever 22 is fitted is formed at the tip of the lock lever 22 . Therefore, when a drive pulse is applied to the solenoid 25, the locking lever 22 is swung against the force of the spring 24. The drive pulse to the solenoid 25 is
For example, it is given as follows depending on the object distance from the distance measuring circuit.

That is, to explain the operation of the above device, FIG. 2 shows that the movable lens barrel 1 is moved against the force of the tension spring 16.
2 is at the initial position (infinity side or short distance side). At this time, the locking pawl 22a locks the first mountain 20a of the ratchet 20, and the locking pawl 22a locks the first ridge 20a of the ratchet 20.
b releases the first ridge 21a of the ratchet 21. In this state, the shutter button is pressed, the distance measuring circuit calculates the object distance (lens movement amount), and the calculation result is converted into a pulse and applied to the solenoid 25. Now solenoid 25 to 1
If pulses are given, plunger 2
6 is attracted and retreats, and the locking lever 22 is released by the spring 2.
It is made to swing against the force of 4. Then, the locking claw 2
The locking of the first ridge 20a of the ratchet 20 by the latch 2a is released, and the lens driving ring 15 begins to rotate clockwise by the spring 16. However, at the next moment, the locking pawl 22b locks the second ridge 21b of the ratchet 21, so the lens drive ring 1
5 stops rotating.

Since the solenoid 25 is energized only instantaneously by the drive pulse, the locking lever 22 swings clockwise by the spring 24 at the next instant. Then, the locking of the second ridge 21b of the ratchet 21 by the locking claw 22b is released, and the locking claw 22a now locks the second ridge 21b of the ratchet 20.
The peak 20b is locked to stop the rotation of the lens drive ring 15, that is, the movable lens barrel 12.

In this way, by applying one drive pulse to the solenoid 25, the lens drive ring 15 rotates by one pawl of the latches 20 and 21, and the movable lens barrel 12 rotates via the interlocking pin 17. and move in the optical axis direction. Therefore, when the solenoid 25 is energized with two pulses, the lens drive ring 15 rotates by two claws, and when the solenoid 25 is energized with three pulses, it rotates by three claws. This means that the amount of movement of the lens can be reliably controlled by the number of pulses, so if a number of drive pulses are given to the solenoid 25 according to the distance to the subject by the distance measuring circuit,
It becomes possible to quickly advance the lens to a predetermined position.

Then, when the shutter (not shown) is opened and shooting is completed, the lens drive ring 15 is rotated against the biasing force of the spring 16 by a charging member (not shown) and locked at the same time as the next film is wound. When the claw 22a is returned until it engages with the first ridge 20a of the ratchet 20, the movable lens barrel 12 returns to its initial position.

3 and 4 show a second embodiment of the invention. The pivot 32 installed on the main board 11 has
A locking frame 33 surrounding the lens drive ring is pivotably mounted, and locking pawls 33a and 33b that engage with the latches 20 and 21 of the lens drive ring 15 are opposed to the inner surface of the locking frame 33. It is provided.
This locking frame 33 is fixed to the locking claw 3 by a spring 34.
3a is biased to swing in the direction of engagement with the ratchet 20. The relationship between the locking claws 33a and 33b is the same as the relationship between the locking claws 22a and 22b in the first embodiment.

A coil holding plate 36 is attached to this locking frame 33.
is formed to extend, and the movable coil 35 is held on this coil holding plate 36. On the other hand, a coil holding plate 37 is formed extending from the outer periphery of the lens driving ring 15, and faces the coil holding plate 36, and a movable coil 38 is fixed to this coil holding plate 37. A single fixed permanent magnet 39 is located between the moving coils 35 and 38. The movable coil 35 and the permanent magnet 39 constitute an electromagnetic actuator for the locking frame 33, and the movable coil 38 and the permanent magnet 39 constitute an initial position return driving means for returning the lens drive ring 15 to the initial position. There is.

The operation of this embodiment will be explained with reference to FIG. The illustrated state is the initial position. This is calculated by the distance measuring circuit, and the number of pulses corresponding to the required movement value of the movable lens barrel 12 is energized to the movable coil 35. When the number of pulses is one, the locking frame 33 swings once against the force of the spring 34, and the first peak 20 is formed by the locking claw 33a.
a is released, and the lens drive ring 15 rotates in the biased direction by the spring 16. Then, the next instantaneous locking pawl 22b engages the second ridge 21b of the ratchet 21.
The rotation of the lens drive ring 15 is stopped by engaging with the lens drive ring 15. Next, the locking frame 33 swings counterclockwise, the locking of the second crest 21b by the locking pawl 33b is released, and the second ridge 20b is now unlatched by the locking pawl 33a.
is locked. This operation is repeated according to the number of pulses, and the lens drive ring 15 rotates in stages and stops each time a pulse is output. As a result, the movable lens barrel 12 is moved to a predetermined position.

Then, in this state, the shutter is opened and a photograph is taken. After shooting, the movable coil 38
When a current is applied in a direction that causes the lens drive ring 15 to rotate against the spring 16, the lens drive ring 15 returns to its initial position.

According to this embodiment, the driving, stopping, and returning to the initial position of the photographic lens are performed by the electromagnetic force generated by the moving coil and the permanent magnet, so that the lens is returned to the initial position by the film winding force. There is no need to do this, and the degree of freedom in design increases.

"Effects of the Invention" As explained above, according to the present invention, the lens drive ring is rotated by the lens biasing member due to the action of the ratchet formed on the lens drive ring and the pair of locking pawls of the locking member. can be rotated and stopped by steps on the ratchet teeth.
Therefore, by controlling the energization of the electromagnetic actuator based on the object distance signal from the distance measuring circuit, it is possible to reliably stop the photographing lens at an in-focus position. Therefore, there is no need for a lens position detection device, a speed reduction device, etc. as in the conventional device, and a device with a simple mechanism, high operational reliability, and cost reduction can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view showing one embodiment of the device of the present invention, FIG. 2 is a plan view of the assembled state shown in FIG. 1, and FIG.
The figure is a perspective view showing another embodiment of the device of the present invention.
The figure is a plan view of the assembled state shown in FIG. 3. 12... Photographing lens, 15... Lens drive ring, 16, 24, 34... Spring, 17... Interlocking pin, 20, 21... Ratchet, 22... Locking lever (locking member), 22a, 22b ...Latching claw,
23, 32...Axis, 25...Solenoid, 3
5, 38... Moving coil, 33... Locking frame (locking member), 39... Permanent magnet.

Claims (1)

[Scope of Claims] 1. A movable lens barrel movable in the optical axis direction, with the optical axis of the movable lens barrel as the center of rotation, and the movable lens barrel moving in the optical axis direction as the movable lens barrel rotates. In an autofocus camera, the autofocus camera is equipped with a lens drive ring that rotates the lens drive ring, and a ring biasing means that rotationally biases the lens drive ring in either direction, and controls the rotational position of the lens drive ring according to the subject distance. A processing position return device is provided for rotating the lens drive ring to the initial position against the ring biasing means, a ratchet is formed in the circumferential direction on the lens drive ring, and a pair of ratchets are provided on the outside of the lens drive ring. a locking member having a pawl, one of which selectively engages with the ratchet to prevent rotation of the lens driving ring by the ring biasing means; further, the locking member an electromagnetic actuator that swings the lens drive ring and alternately engages the pair of locking pawls with the ratchet to allow the lens drive ring to rotate by the ring biasing means in stages. Autofocus camera lens drive device. 2. In claim 1, the locking member is provided with a locking member biasing means for urging the one of the locking claws in a direction to engage the ratchet. Drive device. 3. In claim 2, the electromagnetic actuator is configured to:
A lens driving device for an autofocus camera, which is a solenoid that swings the locking member against the locking member biasing means to engage the other locking pawl with the ratchet. 4. In claim 2, the electromagnetic actuator includes a moving coil fixed to the locking member and a fixed permanent magnet facing the moving coil, and each time a drive pulse is applied to the moving coil, A lens driving device for an autofocus camera that swings the locking member against the locking member biasing means. 5. In claim 4, a movable coil facing the fixed permanent magnet is fixed to the lens drive ring, and the fixed permanent magnet and the movable coil move the lens drive ring with the ring. A lens drive device for an autofocus camera that constitutes an initial position return device that rotates the lens to an initial position against a force means. 6. In claim 5, the movable coil fixed to the locking member and the movable coil fixed to the lens drive ring are opposed to each other, and a single fixed permanent magnet is positioned between the two movable coils. The lens drive device of an autofocus camera.