JPS62184440A - Lens driving device for autofocusing camera - Google Patents

Abstract

PURPOSE:To focus accurately a photographing lens and to obtain a highly reliable device with a simple constitution by locking a locking part claw with a ratchet gear formed on a lens driving ring based on a pulse signal outputted from a range finding circuit. CONSTITUTION:When a claw 22a of a locking lever 22 is locked with the gear 20a of the ratchet 20 and a shutter button is depressed under the state that a claw 22b is separated from a gear 21b, a lens moving distance calculated by the range finding circuit is converted into a pulse and the pulse is impressed to a solenoid, so that a plunger 26 is sucked, the claw 22a is unlocked from the gear 20a, the claw 22b is locked with the gear 21b, a lens driving ring 15 is rotated in the clockwise direction by a spring 16 to control the moving distance of the lens in accordance with the number of pulses. After the end of photographing, the ring 15 is rotated against the spring 16 by a charging member simultaneously with film winding and the locking claw 22a is returned until it is locked with the gear 20a so as to be restored to the initial state.

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).
The lens driving ring is biased to rotate in either direction, and the rotation angle of the lens driving ring is controlled against the spring means depending on the distance to the object. The return of the movable lens barrel to its initial position is generally performed in conjunction with the shutter charge.

However, this conventional device requires a device (such as a code board) to raise the lens position, a device (such as a governor) to gradually move the lens, and a device (such as a governor) that allows the lens to come to a position that matches the subject distance. Since a latch mechanism or the like is required to lock the device when the device is turned, the number of mechanical parts increases, making the mechanism complicated and increasing costs.

[Object of the Invention] An object of the present invention is to solve the above-mentioned conventional problems and provide a lens driving device N that can drive and stop a photographic lens with a simple mechanism.

"Summary of the Invention" The present invention provides a movable lens barrel supported movably in the optical axis direction, in which a circumferential ratchet pawl is formed on a lens drive ring that provides movement in the optical axis direction as the lens rotates. ,
A locking member is pivotally mounted on the outside of the lens drive ring, and either one of the ratchet pawl and the Y-claw can be selectively engaged with the locking member, and when engaged, the lens drive ring is biased. a pair of locking pawls for preventing the locking member from being rotated by the ratchet; and a biasing means for urging the locking member in a direction in which one of the locking pawls engages with the ratchet; It is characterized by being provided with an electromagnetic actuator that swings the locking member and engages the other locking pawl with the ratchet.

“Embodiments of the invention” Embodiments of the present invention will be described in detail below with reference to the drawings.

1 and 2 show a first embodiment of the present invention. A fixed lens barrel 13 supporting a movable lens mirror (taking lens) 12 is fixed to an OM plate 11. FIG. A female helicoid 13a is cut into the inner circumference of this fixed lens barrel 13,
The male helicoid portion 14 of the movable lens barrel 12 is 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 this movable lens barrel 12, the fixed lens barrel 1
A lens drive ring 15 is rotatably fitted on the outer periphery of the lens 3 . This lens drive ring 15 is an interlocking bin 171F that protrudes toward the movable lens barrel 12! : The interlocking pin 17 is inserted into an interlocking hole 19 formed in the flange 18 of the movable lens barrel 12. Therefore, the movable lens barrel 12 always rotates in the same manner as the lens drive ring 15. This lens drive ring 15
is biased to rotate in one direction by a tension spring 16,
When no force is applied to the ring 15, the movable lens barrel 1
2 moves to the shortest photographing position or the infinite photographing position. The lens drive ring 15 and the movable lens mirror WR12 support the movable lens barrel 12 so that it can only move linearly in the optical axis direction, while the lens drive ring 15 has a cam that engages with the movable lens barrel 12. A surface may be formed so that the movable lens space 12 moves in the optical axis direction as the ring 15 rotates.

This lens drive ring 15 has a circumferential ratchet 20, 21 formed on its outer periphery. This ratchet 20.21 is connected to a pair of locking pawls 22 of a locking lever 22.
It may be divided into parts corresponding to a and 22b, or it may be formed continuously.

The locking bar 22 is pivotally mounted on the outside of the lens drive ring 15 by an ↑8 shaft 23, and one of the locking claws 22a is urged to rotate in the direction of engagement with the ratchet 2o by a spring 24. There is. One of the pair of locking pawls 22a, 22b selectively engages with the ratchets 20 and 21, and both do not engage with the ratchets at the same time.

This ratchet 20.2], the locking pawl 22a,
22b is provided in a direction that resists the force of the spring 16 and prevents the lens drive ring 15 from rotating when engaged.

A solenoid 25 is connected to the locking lever 22 in order to swing the locking lever 22 against the force of the spring 24. This solenoid 25 has a plunger 26 that normally retreats when an ejection drive pulse is applied.
A pin hole 27 is formed at the tip of the plunger 26 into which a bottle 28 placed on the locking lever 22 is fitted. Therefore, when a driving pulse is applied to the solenoid F: 25, the first locking collar 22 is swung against the force of the spring 24. A driving pulse to the solenoid 25 is given, for example, as follows, depending on the distance to the subject from the distance measuring circuit.

That is, to explain the operation of the above-mentioned equipment, FIG. 2 shows that the movable lens barrel 12 is moved to the initial position (
It shows a state on the infinity side or short distance side). At this time, the locking pawl 22a is 20a% of the first peak of the ratchet 2o.
The locking pawl 22b engages the first thread 21a of the ratchet 21.
The lock is released. In this state, the shutter button is pressed, the distance measuring circuit calculates the subject distance M (lens movement amount), and the calculation result is converted into a pulse and sent to the solenoid l-
If one pulse is now applied to the solenoid 25, the plunger 26 is attracted and moves back, and the locking lever 22 is swung against the force of the spring 24.Then, the locking occurs. The locking of the first thread 20a of the ratchet 20 by the pawl 22a is released, and the lens drive ring 15 begins to rotate clockwise by the spring 16. However, at the next moment, either the pawl 221) or the ratchet 21 Since the second ridge 21b is locked, the rotation of the lens drive ring 15 is stopped.

Since the solenoid 25 is energized only instantaneously by the drive pulse, the locking lever 22 swings clockwise by the spring 24 at roughly the next instant. Then, the second thread 21 of the ratchet 21 by the locking pawl 22t)
t) is released, the locking pawl 22a locks the second thread 2ObV of the ratchet 20, and the lens drive ring 1
5, that is, the rotation of the movable lens barrel 12 is stopped.

In this manner, by applying one drive pulse to the solenoid 25, the lens drive ring 15 is moved to the ratchet 20.2.
Accordingly, the movable lens barrel 12 rotates via the interlocking pin 17, and moves in the optical axis direction. Therefore, when the solenoid 25 is energized with two pulses, the lens drive ring 5 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 by applying a number of drive pulses to the solenoid 25 that corresponds to the distance to the object by the distance measurement circuit, it is possible to quickly move the lens to a predetermined position. becomes.

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

Figures 3 and 4 show a second embodiment of the present invention.

A locking frame 33 that surrounds 15% of the lens drive ring is pivotally attached to a pivot 32 set on the main plate 11, and a ratchet 20. Locking pawls 33a, 33t) that engage with 21 are provided facing each other. This locking frame 33 is held by a spring 34.
The locking pawl 33a 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 34 is formed to extend from this locking frame 33, and a movable coil 35 is held on this coil holding plate 34. 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 34, 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 moving coil 35 and the permanent magnet 39 constitute an electromagnetic actuator for the locking frame 33, and the moving coil 38 and the permanent magnet 39 constitute an initial position return drive 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 movable coil 35 is energized with a number of pulses corresponding to the required movement value of the movable lens barrel 12. If the number of pulses is 1 pulse, the locking frame 33 swings once against the force of the spring 34, and the locking claw 33
The locking of the first ridge 20a by a is released, and the lens drive ring 15 rotates in the biasing direction by the spring 6. and the second thread 21b of the next instantaneous locking pawl 22b or ratchet 2.
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, and the locking claw 33
The locking of the second crest 21b by the second ridge 21b is released, and the second ridge 20b is now locked by the locking claw 33a. This operation is repeated according to the number of pulses, and the lens drive ring 15 rotates toward the mold cylinder in stages and then stops. As a result, the movable lens barrel] 2 is advanced to a predetermined position.

Then, in this state, the shutter is opened and a photograph is taken. After photographing is completed, if a current is applied to the movable coil 38 in a direction that causes the lens drive ring 15 to rotate against the spring 16, the lens drive ring 15 will be restored to its initial position. As described above, 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.
There is no need to use film winding force to return the lens to its initial position, increasing the degree of freedom in design.

Note that in this embodiment, the spring 16 is eliminated, and instead,
By applying a current in the opposite direction to the movable coil 38 during the initial position return operation, the lens driving ring 15 can be biased to rotate in the same direction as the biasing direction by the spring 6.

"Effects of the Invention" As explained above, according to the present invention, the lens drive ring is rotated and rotated by the steps of the ratchet teeth by the action of the ratchet formed on the lens drive ring and the pair of locking pawls of the locking member. It can be stopped. Therefore, by controlling the energization of the electromagnetic actuator based on the subject distance signal from the distance measuring circuit, it is possible to reliably stop the photographic lens at the focused 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 drawings]

Fig. 1 is an exploded perspective view showing one embodiment of the device of the present invention;
The figures are a plan view showing the assembled state shown in FIG. 1, FIG. 3 a perspective view showing another embodiment of the device of the present invention, and FIG. 4 a plan view showing the assembled state shown in FIG. 3. 12... Photographing lens, 15... Lens drive ring,
16.24.34... Spring, 17... Interlocking bottle, 2
0.21...Ratchet, 22...Latching lever (locking member), 22a, 22b...Latching pawl, 23.3
2... Axis, 25... Solenoid, 35.38...
・Movable coil, 33...locking frame (locking member), 39・
··permanent magnet. Patent applicant Asahi Optical Industry Co., Ltd. Agent
Kunio Miura and Shigeru Matsui Figure 2 16 Figure 3 Procedures Amendment Written by the Commissioner of the Patent Office, October 22, 1986. /, Indication of the case Patent application No. 1983-27485 λ0 Name of the invention Lens drive device 3 of an autofocus camera, person who makes correction Relationship to the case Patent applicant address 2-3699 Maeno-cho, Itabashi-ku, Tokyo Name (0
52) Asahi Optical Industry Co., Ltd. Representative Toru Matsumoto 1 174 Telephone: 03-960-5162 In the "Description" column. "Step" in the 5th line of page 10 and the 14th line of page 12 is corrected to "escape A."

Claims (5)

[Claims] (1) A movable lens barrel that is movable in the optical axis direction, and a lens drive ring that rotates around the optical axis of this movable lens barrel and moves the movable lens barrel in the optical axis direction as the movable lens barrel rotates. and a biasing means for rotationally biasing the lens drive ring in either direction, and the rotation angle of the lens drive ring is controlled in accordance with the subject distance against the biasing means. In the lens driving device, a ratchet pawl is formed in the lens driving ring in the circumferential direction, a locking member is pivotally attached to the outside of the lens driving ring, and the locking member has one of the ratchet pawls. is selectively engageable, and forms a pair of locking pawls that prevent rotation of the lens drive ring by the biasing means when engaged, and furthermore, one of the locking pawls engages this locking member with a ratchet. The invention is characterized in that it includes a biasing means for biasing the locking member in the direction of engagement with the ratchet, and an electromagnetic actuator that swings the locking member against the biasing means and engages the other locking pawl with the ratchet. Autofocus camera lens drive device. (2) The lens drive device for an autofocus camera according to claim 1, wherein the electromagnetic actuator is a solenoid that swings the locking member against the biasing means every time a drive pulse is applied. (3) In claim 1, the electromagnetic actuator is composed of a moving coil fixed to a locking member and a fixed permanent magnet facing the moving coil, and each time a driving pulse is applied to the moving coil, , a lens drive device for an autofocus camera that swings a locking member against a biasing means. (4) In claim 1, a movable coil facing a fixed permanent magnet is fixed to the lens drive ring, and the permanent magnet and the movable coil push the lens drive ring against the biasing means. A lens drive device for an autofocus camera that constitutes an initial position return drive means for rotating the lens. (5) In claim 3 or 4, the movable coil fixed to the locking member and the movable coil fixed to the lens drive ring are opposed to each other, and between the two movable coils, An autofocus camera lens drive in which a single fixed permanent magnet is located.