JPS62187329A - Lens driving device for autofocus camera - Google Patents

Abstract

PURPOSE:To drive a lens barrel and control its position, and to improve the reliability by inputting pulses whose number corresponds to subject distance to a solenoid, and rotating a ratchet mechanism and driving a lens driving ring. CONSTITUTION:At the time of a shutter button is pressed, a distance measuring circuit calculates the subject distance and supplies pulses whose number corresponds to the distance to the solenoid 23. a plunger 24 is attracted and a feed claw lever 16 draws a ratchet 16 by the number of the supplied pulses through the counterclockwise rotation of a lever 19, thereby placing the lens barrel in an infocus state through the clockwise rotation of the driving ring. When a pin 17 kicks up a lever 29 on the end of photography, pins 33 and 34 push up the levers 16 and 28 away from the ratchet 15 and the ring 11 returns its initial position where it contacts a pin 14. Thus, the lens is driven and its position is controlled by the simple structure in which power-feeding control over the solenoid 23 is only performed, thereby improving the reliability.

Description

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

"Prior Art and its Problems J" 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,
The rotation angle of the lens drive ring is regulated against this spring means depending on the distance to the subject. 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 (such as a code plate) to detect the lens and a device (M) to gradually move the lens.
governor, etc.), and also requires a latch mechanism to lock the lens when it reaches a position appropriate for the subject distance, which increases the number of mechanical parts, complicates the mechanism, and increases costs. There is.

[Object of the Invention] The present invention solves the above conventional problems and provides a lens driving device that drives a movable lens barrel, stops it at a predetermined position, and returns it to its initial position using a simple mechanism. With the goal.

``Summary of the Invention J The present invention forms a circumferential ratchet on a lens drive ring that moves a movable lens barrel in the optical axis direction as it rotates, and engages and disengages with this ratchet using an electromagnetic actuator. an electromagnetic drive latch feed mechanism that has a feed pawl and rotates the lens drive ring in steps against its rotation urging means; and the electromagnetic drive latch feed mechanism causes the lens drive ring to act as a rotation urging means The present invention is characterized in that a latch release means is provided for releasing the locking of the lens drive ring by the latch feed mechanism when the rotation end in the opposing direction is reached.

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

FIG. 1 shows a first embodiment of the invention. The lens drive ring 11 is rotatable around the optical axis, and is configured to move the movable lens barrel (taking lens) 10 in the optical axis direction as the ring rotates. This interlocking structure is obtained, for example, by screwing the movable lens barrel 1o into the fixed S, and fitting the interlocking bottle 10a, which is erected on the movable lens chain portion 10, into the interlocking groove 11a of the lens drive ring 11. Further, the movable lens mirror M10 can be supported so as to be movable only in the direction of the optical axis, and can be engaged with the cam surface of the lens drive ring 11 to form a similar interlocking structure.

The lens drive ring 11 is urged by a restoring spring 12 to rotate in a direction in which the protrusion 13 comes into contact with the fixed stopper 14 , and this stopper 14 causes the lens drive ring 11 to be rotated.
One end of rotation is regulated. This state is the shortest photographing position or the infinite photographing position of the movable lens barrel. A ratchet 15 having a plurality of claws continuous in the circumferential direction is formed on the outer periphery of the lens drive ring 11. This lens drive ring 15 has an unlocking dowel 17 implanted therein.

An intermediate lever 19 is pivotally attached to a fixed pivot shaft 18 on the outside of the lens drive ring 11, and a feed pawl lever 16 is pivotally attached to a swing shaft 20 provided at one end of the intermediate lever 19. The feed pawl lever 16 is moved by the spring 21 so that the feed pawl lever 16
6a is biased to swing in the direction of engagement with the ratchet 15. This feed claw lever 16 is connected to the intermediate lever 19.
When the spring 22 swings counterclockwise against the force of the spring 22,
It is pulled through the swing shaft 2o, and the ratchet 15 is pulled by the feed pawl 16a, causing the lens drive ring 11 to rotate.

In order to swing the intermediate lever 19 against the force of the spring 22, a solenoid 23 is connected to the other end of the intermediate lever 19. This solenoid 23 has a plunger 24 that normally advances and retreats when a driving pulse is applied, and a dowel 26 placed on the intermediate lever 19 is fitted into a bottle hole 25 at the tip of the plunger 24. There is. Therefore, when a drive pulse is applied to the solenoid 23, the intermediate lever 19 is swung against the force of the spring 22. A drive pulse to the solenoid 23 is given depending on the distance to the subject from a distance measuring circuit (not shown). 27 is a stopper that restricts the protruding end of the plunger 24.

Roughly, a latch lever 28 that engages with the ratchet 15 to stop the rotation of the lens drive ring 11 in the urging direction, and a feed pawl 16 are provided on the rotation axis 3o on the outside of the lens drive ring 11.
A latch release lever 29 for releasing the engagement with the ratchet 15 of a is coaxially pivoted. The latch lever 28 is caused by a spring 31 so that its locking pawl 28a engages with the ratchet 15.
It is biased to swing in the direction of engagement. The latch release lever 29 is biased by a spring 32 in a direction in which a kick-up pin 33 provided at the front end thereof comes into contact with the ratchet 15.

The latch release lever 29 has a release arm portion 35 projecting toward the lens drive ring 11 side. This release arm 35 is pressed by the lock release pin 17 when the lens drive ring 11 is rotated by the feed pawl lever 16 and reaches the end in the opposite biasing direction to the biasing direction by the spring 12. , the latch release lever 29 is swung in the opposite direction. The kick-up pin 33 is located below the slope 16b of the feed pawl 16a, and kicks the feed pawl 16a up 11 when the latch release lever 29 swings in the opposite biasing direction, thereby disengaging the feed pawl 16a from engagement with the ratchet 15. .

Also, the latch release lever 29 has a position 11 on the cylindrical end of the latch lever 28! A release button 34 is provided. When the latch release lever 29 swings in the counter-biasing direction, the release lever 34 releases the locking lever 28 from the ratchet 15.
This is to remove it from the mesh. That is, when the release arm 35 of the latch release lever 29 is pushed by the lock release pin 17 of the lens drive ring 11, the claws 28a and 16a that were engaged with the ratchet 15 are disengaged, and the lens drive ring 11 is in a free state. As a result, the spring 12 can rotate it to the return end.

The rotational position of the latch release lever 29 is regulated by a positioning lever 37 pivotally mounted on a fixed pivot 36 on the outside of the lens drive ring 11. This positioning lever 37 is held by a spring 40
, the lever stopper piece 39 is released from the latch release lever 2.
It is rotationally biased in the direction of engagement with the engagement recess 29a and release holding step 29b of No.9. When this lever stopper piece 39 is engaged with the engagement step portion 29a, the latch lever 28
The locking pawl 28a can be held by the ratchet 15, and the kick-up pin 33 of the latch release lever 29 can be held by the feed pawl 16a.
On the other hand, when the lever stopper piece 39 engages with the release holding step 29t), the locking pawl 28a disengages from the ratchet 15 and the kick-up 1 nubbin 3
3 kicks up the feed pawl 16 to release the locking lever 37 from the ratchet 15. This positioning lever 37 is activated by the lens drive ring 11 being rotated by the spring 12 and released by the unlocking lever 17. When is pressed, the lever stopper piece 3
9 rotates in the direction to engage with the engagement recess 81329a.

As is clear from the above explanation, the feed pawl lever 16, the intermediate lever 19, the solenoid 23, and the latch lever 2
8 is a lens driving ring 11 using a ratchet 16.
It constitutes an electromagnetic drive latch feeding mechanism that rotates the latch in steps. Also, the lock release pin 17 of the lens drive ring 11
, the latch release lever 29, and the position stop lever 37 constitute a latch release mechanism when the lens drive ring 11 reaches the rotation end in the direction opposite to the biasing direction of the spring 12.

Therefore, the present device having the above configuration operates as follows. FIG. 1 shows a state in which the lens driving ring 11 is at the initial position (the shortest photographing position or the infinite photographing position M). At this time, the feed pawl 16a engages with the first pawl of the ratchet 15, the locking pawl 28a of the latch lever 28 engages with the pawl disposed on the first pawl, and the kick-up door 33 of the latch release lever 29 It is located below and in contact with the feed claw 16a. Further, the position stop lever 37 engages with the engagement recess 29a with its lever holding piece 39, and the latch release lever 2
The 9th place N is fixed.

In this state, the shutter button is pressed, the distance measuring circuit calculates the object distance (lens movement amount), and the result is converted into a pulse and given to the solenoid 23. Now, if one pulse is given to the solenoid 23, the plunger 24 is attracted and retreats, and the intermediate lever 19 is moved by the spring 22.
is swayed against the force of Then, feed claw lever 1
6 moves and pulls the first pawl with the feed pawl 16a, resisting the force of the lens drive ring 11 and tension spring 12 and rotating in the counter-biasing direction by one pawl step. At this time, the locking claw 28a
engages with the next pawl while making contact with the top of the pawl, and stops rotation of the lens drive ring 11 in the urging direction by one pawl or more. Then, when the current supply is stopped, the force of the spring 22 acts to move the feed pawl lever 16 forward, and the feed pawl 16a becomes ready to engage with the next second pawl. Since the solenoid 23 is energized instantaneously by a drive pulse, the operation during this time is instantaneous.

In this way, by applying one pulse to the solenoid 23, the lens drive ring 11 rotates by one pawl of the ratchet 15, and the movable lens barrel rotates in conjunction with this.
Move in the direction of the optical axis. Therefore, when the solenoid 23 is energized with two pulses, the lens drive ring 11 rotates by two claws, and when the solenoid 23 is energized with three pulses, it rotates by three claws.

This means that the amount of movement of the movable lens barrel 10 can be reliably controlled by the number of pulses, so by giving the solenoid 23 a number of drive pulses that correspond to the distance to the subject by the distance measuring circuit, the lens can be quickly moved to a predetermined position. It is possible to move it to.

Then, when the shutter (not shown) opens and the photograph is completed, the solenoid 2 is turned on again to return the lens to its initial position.
A driving pulse is given to 3. This point is one of the features of the present invention. This number of pulses is based on the number of pulses required for the lens drive ring 11 to rotate from the initial position to the final position (which can be set arbitrarily depending on the design). This is the number obtained by subtracting the number of pulses applied. This remaining number of pulses is calculated by the distance measuring circuit. To return the lens to the initial position, pulses are continuously given to the solenoid 23, and when the lens drive ring 11 reaches the final position, a limit switch (not shown) is activated to turn off the power to the solenoid 23. It may be configured to end.

In this way, when you apply a driving pulse to the solenoid 23,
By exactly the same operation as described above, the feed pawl 16a and the locking pawl 28a sequentially engage with the pawl of the ratchet 15, and the lens II! The movable ring 11 is rotated in the counter-biasing direction to the final position. As the lens drive ring 11 rotates, the lock release pin 17 pushes up the release arm 35 of the latch release lever 29 against the force of the spring 32. Then, the kick-up pin 33 at the tip of the latch release lever 29 moves to the feed pawl 1.
6b @ Kick up to disengage the feed pawl 16a and ratchet 15, and at the same time, the release pin 34 is released from the latch lever 2.
8 is pushed down against the force of the spring 31, and the engagement of the ratchet 15 by the locking pawl 28a is also released. At this time, the position stop lever 37 swings counterclockwise due to the force of the spring 4o, and the lever holding piece 39 enters into the release holding step 29t) of the latch release lever 29 to stop the latch release lever 29 in position. In this state, the solenoid 23 is de-energized, and the lens drive ring 1 becomes free and rotates in the urging direction by the tension spring 12.

When the lens drive ring 11 rotates in the urging direction and the protrusion 13 comes into contact with the stopper 14, the lock release pin 1
7 comes into contact with the arm portion 38 of the positioning lever 37 and swings the positioning lever 37 clockwise. As a result, the lever holding piece 39 falls from the release holding step 29b into the engagement recess 29a, so the spring 32 and the spring 31 act simultaneously to swing the latch release lever 29 and latch lever 28 in the direction of engagement, and the feed claw 16a engages with the first pawl of the ratchet 15, and the locking pawl 28a engages with the pawl of the ratchet 15 in its initial state, and the lens drive ring 11 abuts against the stopper ]4 and returns to its initial position. As described above, according to the present invention, by simply controlling the drive pulse applied to the solenoid 23, it is possible to perform a series of operations from driving the lens to fixing it at a predetermined distance measurement position and returning to the initial state.

FIG. 2 shows a second embodiment of the invention. In this embodiment, the intermediate lever 19 is biased counterclockwise by a spring 22, and the force of the spring 22 causes the feed pawl lever 16 to swing, thereby rotating the lens drive ring 11 in the counter-biasing direction. I'm here. The solenoid 23 acts to sequentially engage the feed pawl 16a7: the pawl of the ratchet 15.

The operation of this configuration is such that when one pulse is applied to the solenoid 23, the feed pawl 16a engages with the second pawl of the ratchet 15, and is then pulled by the force of the spring 22, causing the lens drive ring 11 to move in the opposite direction. Rotate one claw. and,
To return the lens drive ring 11 from the predetermined position to the initial position, pulses are continuously applied to the solenoid 23, the lens drive ring 11 is rotated to the rotation end in the opposite biasing direction, and the latch release mechanism is activated. When the protrusion 13 comes into contact with the stopper 14, the energization may be stopped by a limit switch or by time control.

According to this embodiment, even when the voltage supplied to the solenoid 23 is strong and the moving speed of the plunger 24 is fast, the rotation of the lens drive ring 11 by the feed pawl lever 16 is performed by the force of the spring 22. If the spring force of the 221Fr tension spring 12 is set to a necessary and sufficient spring force, the lens drive ring 11 can be rotated reliably by one claw per pulse. Therefore, even if the pulses given to the solenoid 23 are unstable due to changes in performance due to changes in the state of charge or temperature of the battery that supplies power to the solenoid 23, the rotation of each pawl of the lens drive ring 11 in the counter-biasing direction is prevented. Guaranteed.

FIG. 3 shows a third embodiment of the invention. In this embodiment, a coil holding plate 41 is formed to extend from the intermediate lever 9, and a movable coil 42Iv is fixed to this coil holding plate 41. A fixed permanent magnet 43 is opposed to the movable coil 42 to constitute an electromagnetic actuator. In this embodiment, when the movable coil 42 is energized with a pulse corresponding to the required movement value of the movable lens barrel, the intermediate lever 19 swings around the pivot shaft 18, and the lens drive ring is rotated by the feed pawl lever 16 and the ratchet 15. 11 step rotations can be obtained.

FIG. 4 shows a fourth embodiment of the present invention. In this embodiment, the intermediate lever 19 is driven by a rotary actuator 44.

That is, the swinging arm 45 of this rotary actuator 44
A bottle 47 erected on the intermediate lever 19 is fitted into a bottle hole 46 formed at the tip of the lever. According to this embodiment, when the rotary actuator 44 is energized with a necessary pulse, the swing arm 45 swings, the intermediate lever 19 swings accordingly, and the lens is driven by the feed pawl lever 16 and the ratchet 15. A step rotation of the ring 11 is performed.

"Effects of the Invention" As explained above, the device of the present invention has a ratchet formed on the lens drive ring, an electromagnetic drive latch feed mechanism that rotates the lens drive ring in steps, and a lens drive mechanism using the electromagnetic drive latch feed mechanism. A latch release means is provided that releases the lens drive song from the latch feed mechanism when the ring reaches one rotation end, so that the lens can be controlled from drive to position control to initial position simply by controlling the energization of the electromagnetic actuator. The return can be performed with high operational reliability. Furthermore, compared to conventional devices, it is possible to obtain a device that has a simpler mechanism and can reduce costs. Roughly, the initial stage of the lens! Since the return is performed without relying on one push of film winding, the degree of freedom in design is increased.

[Brief explanation of drawings]

FIG. 1 is a front view of a first embodiment of the lens-driven snow making device according to the present invention, FIG. 2 is a front view of a second embodiment of the device of the present invention, and FIG.
The figure is a partial front view showing a third embodiment of the apparatus of the present invention, and FIG. 4 is a partial front view showing a fourth embodiment of the apparatus of the present invention. 10... Movable lens between mirrors, 11... Lens drive ring, 12.22.31.32.40... Spring, 15.
...Ratchet, 16...Feed pawl lever, 16a...
・Feeding claw, 17... Lock release pin, 19... Intermediate lever, 23... Solenoid (electromagnetic actuator), 2
4...Plunger, 28...Latch lever, 29.
... Latch release lever, 33 ... Kick-up bin, 34
...Release bottle, 37...Hundred stop lever, 39...
・Lever holding piece, 42... Moving coil (electromagnetic actuator), 43... Fixed permanent magnet (electromagnetic actuator)
, 44...Rotary actuator (electromagnetic actuator)
. Patent applicant: Asahi Optical Industry Co., Ltd. Agent
Kuni Miura Mikai Shigeru Matsui Figure 3 Figure 4 cn″′ Company N

Claims (4)

[Claims] (1) A movable lens barrel that can move in the optical axis direction, and a lens drive ring that rotates around the optical axis of this movable lens barrel and moves this movable lens barrel in the optical axis direction as it rotates. and a biasing means for rotationally biasing this lens drive ring in either direction, and controlling the rotation angle of the lens drive ring against the biasing means according to the subject distance. In the drive device, the lens drive ring is formed with a ratchet in the circumferential direction, and has a feed pawl that engages and disengages from the ratchet by an electromagnetic actuator, and the lens drive ring is rotated in steps against the biasing means. An electromagnetic drive latch feeding mechanism that moves the
It is characterized by providing a latch release means for releasing the locking of the lens drive ring by the latch feed mechanism when the lens drive ring reaches a rotation end in a direction opposed to the urging means by the electromagnetic drive latch feed mechanism. Lens drive device for autofocus cameras. (2) The lens drive device for an autofocus camera according to claim 1, wherein the rotational force of the lens drive ring by the electromagnetic drive latch feeding mechanism is provided by a spring means that resists the electromagnetic drive force. (3) The lens drive device for an autofocus camera according to claim 1 or 2, wherein the electromagnetic actuator is a solenoid that operates a feed pawl against a spring means every time a drive pulse is applied. (4) The lens drive device for an autofocus camera according to claim 1 or 2, wherein the electromagnetic actuator includes a moving coil and a fixed permanent magnet facing the moving coil.