JPH0248093B2 - JIDOSHOTENKAMERA - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an autofocus camera equipped with a photographing lens focusing device using an electromagnetic drive device.

[Prior art]

Conventionally, when driving a lens unit in a camera for focusing operations, etc., there have been two methods: one using a motor as the driving source, and the other using electromagnetic force as the driving source. In the former case, as used in lens-shutter cameras, after shooting is complete, the shooting lens is driven by a motor to a close-range position when the film is wound, and the position determined by the distance measurement signal is used during shooting. There is a method in which the photographic lens is returned by spring force, and a single-lens reflex camera.
As seen in AF systems, there was a method to drive the photographic lens by changing the amount and direction of rotation of a motor based on distance measurement signals, but all of them required a gear reduction device or a device to convert rotational operation into linear operation. Because of the need for additional components, it has become difficult to incorporate it into modern cameras, which are becoming smaller and lighter.

Therefore, the latter electromagnetic drive method has come to be adopted, but as an electromagnetic drive device used for focusing the photographic lens, the gap between opposing fixed permanent magnets is narrowed, and the magnetic circuit is Considering this on the premise of reducing the loss of
A plurality of movable coil members are arranged, and the photographing lens is driven to a focusing position by rotation or rectilinear movement of the movable coil members.

Therefore, there is a restriction that only two levels of control can be selected depending on the direction of the applied current, that is, from infinite distance to close range or from close range to infinite distance.

Furthermore, two movable coil members are disposed within the gap, one of which changes a cam surface that regulates the position of the photographic lens, and the other that moves the photographic lens into contact with the cam surface. Focus control has also been attempted, but even in this case, control from infinite distance to close range is limited to about 6 steps, and the electromagnetic drive device has disadvantages such as a complicated structure and a large volume. .

One of the ways to solve these functional and structural defects is to convert the signal from the distance measuring device into a pulse current, energize the moving coil member to cause it to swing, and provide this movement outside the electromagnetic drive device. A method has been proposed in which the signal is transmitted to a cam member and the cam member is moved forward.

One of them is a proposal in Japanese Patent Application Laid-open No. 58-43434, which states that by appropriately setting the number of pulse energizations to the movable coil member and the number of steps of the cam member, the photographic lens can be moved to more focused positions. It is possible to control the

However, since the cam member must be returned to its initial position each time a photograph is completed, the structure becomes somewhat complicated, and the advancing mechanism for the cam member is provided within the electromagnetic drive device, resulting in space constraints. Therefore, the cam surface cannot have a sufficient length, making it difficult to increase the precision of the focusing position.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide an autofocus camera that can control a photographic lens to multiple focusing positions with high precision through the action of an electromagnetic drive device.

[Structure of the invention]

In the present invention, a pin provided on a movable coil member of an electromagnetic drive device that swings by pulsed energization accompanying a ranging signal is used to reciprocate a claw provided on a lens barrel. The lens position control cam member integrated with the ratchet wheel is rotated by sequentially stepping the ratchet wheel in one direction around the optical axis, thereby setting the focusing position of the photographing lens corresponding to the distance measurement signal. This automatic camera is characterized by having a cam member for controlling the lens position around the optical axis, and moving the cam member in response to a pulse signal from a distance measuring device to determine the lens position according to the subject distance. Achieved by a focus camera.

〔Example〕

One embodiment according to the present invention is shown in FIGS. 1-5.

FIG. 1 shows an expanded view of a focusing device for a photographic lens in an autofocus camera according to the present invention, and an electromagnetic drive device 100 is attached to a lens barrel (none of which is shown) of the camera, and furthermore, in front A lens drive base plate 110 for holding each member constituting the focusing device is attached to the lens drive base plate 110 by screwing its flange portion 111.

As shown in FIGS. 2 to 4, the electromagnetic drive device 100 includes a holding frame 4 that is integrally connected to the outer periphery of the body 1, permanent magnets 5 equally distributed in the circumferential direction, and the holding frame 4. A coil pattern 6a is provided in the gap between the permanent magnet 5 and the second yoke 3 for controlling the driving of the photographing lens. A first movable coil member 6, which is a movable coil member, and a second movable coil member 7, which is a movable coil member for light quantity control and have a coil pattern 7a, are connected to ring-shaped spacers 11a of two sizes, large and small, as shown in FIG. and 11b, they are arranged in a stacked manner so as to be separated from each other so as not to interfere with each other. Note that the spacers 11a and 11b may be provided in either a fixed or floating state with respect to the holding frame 4.

The first movable coil member 6 repeatedly rotates back and forth in small increments around the optical axis in response to pulse signals from a control circuit corresponding to the detected distance as the distance measuring means built into the camera body operates. Power is transmitted to members of a focusing device, which will be described later, via a swing pin 10 installed above.

The second movable coil member 7 rotates back and forth around the optical axis when energized by the light amount control circuit, and is arranged between the second yoke 3 and the main plate 15 by a set of pins 18 installed therein. A set of shutter blades 14
The opening and closing function is performed using the shaft 16 as a fulcrum.

On the other hand, on the inner surface of the body section 112 of the lens drive base plate 110 attached to the front surface of the electromagnetic drive device 100, there is a body section 141 of the lens drive barrel 140, and further, on the inner surface of the body section 141, there is an outer circumferential portion of the photographing lens frame 130. 131 are rotatably fitted and housed, and the three pins 1 are implanted in the outer peripheral part 131.
32 indicates three inclined grooves 142 provided in the body portion 141 of the lens drive tube 140 and the lens drive base plate 1.
The body 112 is fitted into three straight grooves 113 parallel to the optical axis provided in the body 112 of 10.
It protrudes slightly on the outer periphery.

Further, a lens position control cam member 120 of the present invention is rotatably fitted to the base of the outer periphery of the body portion 112 of the lens drive base plate 110, and a step consisting of three blocks is formed at the end of the body portion 121. Cam 12
2 are incorporated so as to correspond to the pins 132 protruding from the body 112 of the lens drive base plate 110, respectively.

Furthermore, a notch-shaped pawl wheel 123 is formed on the flange portion of the cam member 120, and a pawl 117 attached to an arc-shaped member 116 that swings on the lens drive base plate 110 in the circumferential direction is used to rotate the clock. A claw 124 provided at a fixed position on the front plate of the camera body prevents the camera from reversing.

The pawls 117 and 124 are both biased clockwise by an elastic member (not shown) so as to maintain engagement or contact with the ratchet wheel 123 at all times.

Further, in the arc-shaped member 116, the swing pin 10 of the first movable coil member 6 protruding from the long hole 101 on the front surface of the electromagnetic drive device 100 is further attached to the long hole 114 on the flange portion 111 of the lens drive base plate 110. The arc-shaped member 116 can slide in the circumferential direction along the guide roller 115 installed on the flange portion 111 as the first movable coil member 6 swings. It's getting old.

Further, the body portion 121 of the cam member 120 has three
A book protrusion 125 is provided, and the stepped cam 1
22 rotates and reaches its initial position, a switch 126 is operated to cut off the pulse current to the first moving coil member 6 and stop the advancement of the cam member 120.

On the other hand, a drive motor 170 is housed in the lens barrel, and the shaft 171 of the drive motor 170 is connected to the through hole 103 of the electromagnetic drive device 100 and the lens drive base plate 110. Through hole 11 of flange portion 111
A pinion 172, which is inserted through the shaft 171 and fixed to the tip of the shaft 171, reaches a position where it meshes with the notched gear 143 of the lens drive barrel 140. That is, the rotation of the drive motor 170 rotates the lens driving barrel 140, so that the photographing lens 133 attached to the lens frame 130 can be moved in the direction of its optical axis.

The effects of this embodiment will be explained below.

When the control circuit energizes the number of pulses corresponding to the detection distance in response to a signal from the distance measuring device of the camera body, the first movable coil member 6 and, therefore, the swing pin 10 also receive pulses in the circumferential direction. Repeat the oscillation according to the number.

As a result, the claw 117 of the arc-shaped member 116 moves the cam member 120 clockwise and rotates, moving the stepped cam 122 corresponding to the detection distance to the lens frame 1.
It is set at a position facing the pin 132 of No. 30 and stopped.

Next, the drive motor 170 starts rotating clockwise in response to a signal from the control circuit, and the lens drive barrel 140 is rotated counterclockwise, so that the lens frame 130 is moved along the straight groove 113 by the inclined groove 142. Retract linearly and its pin 132
comes into contact with a step corresponding to the detection distance of the step cam 122 to bring the photographing lens 133 into focus, and then the rotation of the drive motor 170 is stopped.

Next, in the electromagnetic drive device 100, the second movable coil member 7 is actuated by energization to open and close the shutter blade 14 to complete exposure, and the drive motor 170 begins to rotate counterclockwise, causing the lens drive barrel 140 to rotate. The lens frame 130 is returned clockwise to its initial position, that is, the position where the lens frame 130 is most advanced, and then stopped.

Thereafter, the control circuit again applies pulse current to the first movable coil member 6, so that the pawl 117 again advances and rotates the cull member 120 in the clockwise direction. The higher step is the pin 13 of the lens frame 130.
When the position facing the switch 12 is reached, the protrusion 125 provided on the circumferential surface of the stepped cam 122 at that position
6 to cut off the pulse current from the control circuit and stop the rotation of the cam member 120.

Thus, the lens driving tube 140 and the lens frame 1
30, the cam member 120 can return to its initial state before photographing, and take a position in which it can repeatedly start the action as described above.

According to the present invention, the cam member 120
Since the focusing position can be set and restored simply by rotating in one direction, there is no need for a so-called reset mechanism.
Since the stepped cam 122 is formed on the circumferential surface of
It has the advantage of being able to control more focus positions.

Furthermore, since the cam member 120 and the pawl 117 etc. that drive it can be accommodated in the lens drive base plate 110, the focusing device can be configured extremely compactly, and the drive motor 170 can be used during the photographing process.
If the system is constructed so that the operation of the system can be temporarily locked, it also has the advantage of being easy to use as a so-called prefocus function.

Reference numeral 150 denotes a presser metal fitting for regulating the positions of the lens drive barrel 140 and the cam member 120 in the optical axis direction, and the lens drive base plate 1 is held down by legs 151.
On the other hand, 161 is a conversion lens that can change the focal length of the photographic lens 133 by combining it with the photographic lens 133, and is inserted and removed on the optical axis by the switching device 160. I'm starting to be able to do it.

FIG. 5 is a time chart showing the programs for each of the above operations in the autofocus camera of this embodiment.

FIG. 6 shows a second embodiment of the present invention, in which members having the same names as those described in the first embodiment have substantially the same functions. A lens drive base plate 210 is attached to the front surface of the electromagnetic drive device 200 via the base, and a notched gear plate 220 and a lens position control plate are attached to the base of the outer circumference of the body 211 that is integral with the base. Cam member 230
A lens frame 240 incorporating a photographing lens 241 is slidably fitted into the inner surface of the lens frame 240.

The lens frame 240 has three pins 242 on its outer periphery that are connected to the body 21 of the lens drive base plate 210.
The lens frame 240 is inserted through three straight grooves 212 parallel to the optical axis provided in the lens frame 240 and is slidable only in the optical axis direction.
Since the pin 242 is constantly pressed in the direction of the lens driving base plate 210 by the three legs 251 of the leaf spring 250 integrated with the presser fitting 260 attached to the front surface of the lens drive base plate 210, the pin 242 It comes into contact with a lens position control cam 231 of 230 and stops, thereby determining the position of the photographing lens 241.

On the other hand, a pin 20 of a first movable coil member 6 (not shown, see FIG. 3), which is a movable coil member for controlling the photographic lens drive in the electromagnetic drive device 200, is inserted into an elongated hole provided in the flange portion of the lens drive base plate 210. 213 and engages with the bifurcated portion 221 of the notched gear plate 220, and the notched gear plate 220
is connected to a pair of pins also on the flange portion through a gear portion provided on a part of its outer periphery, a gear 222 rotating at a fixed position on the flange portion of the lens drive base plate 210, and a gear 223 meshing with the gear portion. 22
4 and is connected to an arcuate gear 225 that can rotate in the circumferential direction around the optical axis so as to be able to transmit uniform rotation.

Furthermore, a first pawl 227 and a second pawl 228 are provided on the protrusion 226 of the notched gear plate 220 and the end of the arcuate gear 225, respectively, and are biased clockwise by an elastic member (not shown). The claws 227 and 228 are provided with the cam member 230.
It occupies a position where it engages with a ratchet wheel 232 formed on the peripheral surface of.

According to such a configuration, the electromagnetic drive device 200
The swing motion of the first movable coil member (not shown) due to pulsed energization is transmitted to the notched gear plate 220 via the swing pin 20, but due to the forward movement of the pin 20 in the clockwise direction. Said first claw 2
27 acts, and the second pawl 228 acts by the counterclockwise return movement, so the cam member 230 is moved twice by one pulse energization, which is extremely efficient. Photography lens 241
Furthermore, the cam member 230 rotates in the same direction and returns to the initial position by pulse energization again after photographing, so it has the same advantages as the previous example, such as not requiring a reset mechanism. We are prepared.

〔Effect of the invention〕

According to the present invention, it is possible to more accurately adjust the distance of the photographing lens to the subject, and it is possible to provide an extremely useful autofocus camera that does not require an operation to reset the focusing device to its initial position. .

[Brief explanation of drawings]

1 and 6 are exploded perspective views of the focusing device in the autofocus camera of the present invention. 2 to 4 are plan, cross-sectional, and perspective views of the electromagnetic drive device used in the camera. FIG. 5 is a time chart of the focusing device shown in FIG. 1. 100,200...electromagnetic drive device, 110,2
10... Lens drive base plate, 116... Arc-shaped member,
117, 124, 227, 228...nail, 12
0,230...Cam member, 122...Step cam, 1
25...Protrusion, 126...Switch, 130,2
40... Lens frame, 132, 242... Pin, 1
33, 241... Photographing lens, 140... Lens drive tube, 150... Presser metal fitting, 170... Drive motor.

Claims (1)

[Claims] 1. An electromagnetic coil member including a movable coil member for controlling the driving of the photographing lens, which swings back and forth around the optical axis by pulse energization from a control circuit corresponding to the detection distance as the distance measuring means operates. a lens driving base plate having a driving device, a body having a plurality of straight grooves parallel to the optical axis, and a base integral with the body, and attached to the electromagnetic driving device via the base; a notched gear plate rotatably provided on the outer periphery of the body of the lens drive base plate; the notched gear plate has an engaging portion that engages with a pin provided on the movable coil member; and a first claw biased in one direction; an arcuate gear plate supported by the base of the lens drive base plate and having a gear portion on a part of its circumferential surface and a second claw biased in one direction; and the reciprocating rocking of the movable coil member. When the notched gear plate is swung, the gear portion on the notched gear plate and the gear portion on the arcuate gear plate are reversed so that the arcuate gear plate is swung in a direction opposite to the direction of the notched gear plate. a gear provided between the two so as to rotate in the direction; a barrel rotatably fitted to the outer periphery of the barrel of the lens drive base plate and having a cam portion corresponding to a detection distance; a lens position control cam member having a pawl and a ratchet wheel with which the second pawl engages, and a plurality of pins on the outer periphery that engage with linear grooves on the lens drive base plate; and a lens frame that is slidably fitted to the inside of the lens position control cam member, and when the movable coil member swings back and forth, the movable coil member is moved through the first pawl and the second pawl, An autofocus camera characterized in that the lens position control cam is configured to continuously rotate in one direction.