JPH048764B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photographic lens driving device for a camera that linearly drives a lens unit using electromagnetic force to enable focusing operations and the like.

[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 is the case with lens shutter cameras, after shooting is complete, the shooting lens is spring-biased to an infinite distance position when the film is wound, and the range is determined by the distance measurement signal at the time of shooting. One method uses a motor to advance the photographic lens to the desired position, and the other uses a distance measurement signal to drive the photographic lens by changing the rotation amount and direction of the motor, as seen in the AF system of single-lens reflex cameras. However, it has become difficult to incorporate these into modern cameras, which are becoming smaller and lighter, as they all require the addition of a gear reduction device or a device that converts rotational action into linear action.

Therefore, the latter electromagnetic drive method has come to be adopted, but the electromagnetic drive device used for focusing the photographic lens narrows the gap between opposing fixed permanent magnets, and Based on the premise of reducing loss, a single moving coil member is disposed within the gap, and the photographing lens unit is driven by this moving coil member.

Therefore, there are two directions depending on the direction of the applied current, that is,
It was only possible to select two-stage control, from infinite distance to close range, and from close range to infinite distance, and it was not possible to move the photographic lens in multiple stages. Of course, it is possible to hold the photographic lens unit at the midpoint of its drive range using a spring balance or by mechanical means, and then drive the photographic lens forward or backward from that midpoint. However, in order to maintain the midpoint position using spring balance, a spring force that is not affected by posture differences is required, as well as an electromagnetic force. must be stronger than the spring force, and in order to mechanically hold the midpoint position, an additional device is required to release the holding member just before the lens is driven. This was also extremely difficult to realize.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photographic lens driving device for a camera that can control a photographic lens to a plurality of focusing positions of three or more points by rectilinear movement of a movable coil member due to the action of electromagnetic force. This is what I did.

[Structure of the invention]

The present invention provides a first movable coil member that is provided integrally with a photographic lens and moves the photographic lens forward or backward in the optical axis direction when energized; a second movable coil member that moves rearward is disposed within a gap of a magnetic circuit made up of a pair of magnetized members formed around the optical axis of the photographing lens;
an engaging member provided on the first movable coil member; and a cam member having a cam rotatably pivoted by movement of the second movable coil member and abuttable by movement of the engagement member; , a holding member that holds the initial position of the cam member, and rotates the cam member when the second movable coil member is energized based on a signal from a distance measuring device that measures the distance to a subject; The photographing lens is driven by energizing the first movable coil member, and the stopping position of the photographing lens is determined by the engagement member coming into contact with a cam of the cam member. This is achieved by the characteristic photographic lens driving device.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS. 1 to 5 attached hereto.

Fig. 1 shows a longitudinal section of a lens barrel incorporating a photographing lens drive device according to the present invention, and Fig. 2 shows its arrows.
This shows a cross section at AA.

Reference numeral 1 designates a lens barrel body. Inside the lens barrel body 1, yokes 3 and 4 with a permanent magnet 2 in between, and a behind-the-scenes shutter unit 5 are fixed by a retaining ring 6.

In the present invention, the polarity of the permanent magnet 2 is arranged so as to generate lines of magnetic force in the optical axis direction,
Further, the yokes 3 and 4 each form a cylindrical outer ring part 3a and an inner ring part 4a, and the inner surface of the outer ring part 3a and the outer surface of the inner ring part 4a have opposite polarities, and the gap therebetween is perpendicular to the optical axis. It forms a magnetic circuit in the direction.

Furthermore, a cylindrical first movable coil member 7 having a coil pattern 7a is provided in the gap between the outer ring portion 3a of the yoke 3 and the inner ring portion 4a of the yoke 4.
are arranged, and the first moving coil member 7 is
A lens frame 10 incorporating a front group 9a and a rear group 9b of a photographic lens 9 is integrally connected.

On the other hand, the lens frame 10 has guide grooves 10a provided at several locations on the outer periphery of its body that are connected to a plurality of balls rotatably held by a presser ring 12 on the inner surface of the inner ring portion 4a of the yoke 4. 11, so that it can move freely forward or backward in the optical axis direction while keeping the optical axis constant, and at the same time, the first movable coil member 7 also moves along the optical axis. It is possible to move back and forth between the inner ring portions 4a.

Further, a cylindrical second moving coil member 8 having a coil pattern 8a is disposed inside the first moving coil member 7, and the second moving coil member 8 has a joint portion 8b provided on its inner periphery. Although the movable coil member is fitted and supported by the inner ring portion 4a, it can move forward or backward in the optical axis direction independently of the first movable coil member.

Note that the front first and second moving coil members 7 and 8
Both are made of a non-magnetic material, such as synthetic resin, and have a coil pattern 7 as shown in FIG.
a, 8a.

Furthermore, on the circumferential surface of the outer ring portion 3a of the yoke 3,
A rotary cam member 21 as shown in FIG. 4 and FIG. 5 showing the arrow BB thereof is pivotally mounted at three locations that equally divide the circumference, each with a support shaft 22 as a fulcrum.

The rotary cam member 21 is connected to the support shaft 22.
The torsion spring 23 wound around the rising portions 21a, 21
b, and then attach both ends of the torsion spring 23 to the pin 2 of the outer ring portion 3a.
4a and 24b, the rotary cam member 21 is maintained in a state in which the left and right sides are balanced as shown in the figure.

Furthermore, the rotary cam member 21 is provided with a cam portion 25 and an elongated hole 26. That is, the cam part 2
5 denotes cam surfaces 25a and 25d on the extension line of the optical axis passing through the support shaft 22, and cam surfaces 25b and 25 connected to the right and left with appropriate curves.
e, 25c, and 25f, each of whose cam surfaces is in the shape of a circular arc centered on the support shaft 22, and furthermore, the distance from the support shaft 22 is the focal point of the photographic lens 9. Corresponding to the position setting, the cam surfaces 25a, 25b, 25c are farther away in this order,
On the contrary, the cam surfaces 25d, 25e, and 25f are formed closer to each other in this order. Further, between the cam surfaces 25a and 25d, a pin 7b, which is an engaging member of the first movable coil member 7 and is fitted through the elongated hole 3b of the outer ring portion 3a, is inserted in a freely movable state.

Further, the elongated hole 26 has the elongated hole 3 of the outer ring portion 3a.
pin 8 of the second movable coil member 8 into which c is fitted.
c is inserted.

Next, the operation of the photographic lens driving device according to the present invention will be explained.

When the camera's release button is pressed, the distance information from the distance measuring circuit is calculated by the control section, and the lens control signal, lens drive signal, and current direction signal are input to the lens drive circuit (none of which are shown). The first moving coil member 7 and the second moving coil member 8 are energized.

That is, when the lens frame 10 incorporating the photographing lens 9 is to be moved forward or backward from the illustrated position according to the calculation result of the control section, first, the coil 8a of the second movable coil member 8 is energized. After the current direction to be applied is determined and energized, the current direction to be applied to the coil 7a of the first movable coil member 7 is determined and energized.

Therefore, for example, if a signal is issued to move the photographic lens 9 one step forward or backward from the position shown in FIG. Therefore, a current is applied to the coil 8a in a direction that moves it to the right, so that the rotating cam member 2 in FIG.
1 occupies a position rotated by a predetermined angle clockwise by the action of the pin 8c.

Next, when the direction of movement of the photographing lens 9 is, for example, in the front direction, a current is applied to the coil 7a in a direction such that the first movable coil member 7 moves to the left by electromagnetic force. The pin 7b of the first movable coil member 7 comes into contact with the cam surface 25b of the cam portion 25 and stops, and at the same time the lens frame 10, that is, the photographing lens 9 is stopped. That is, the photographing lens 9 is moved forward one step by the signal from the distance measuring circuit and is focused on the subject.

On the other hand, if the moving direction of the photographic lens 9 is backward, a current in the opposite direction is applied to the coil 7a.
As a result, the first movable member 7 moves to the right, the pin 7b comes into contact with the cam surface 25e and stops, and the photographing lens 9 is retracted one step backward to focus on the subject.

Similarly, when a signal is issued to move the photographing lens 9 two steps forward or backward from the position shown in FIG. 1, the second movable coil member 8 moves to the left by the action of electromagnetic force. Since a current is applied to the coil 8a in a direction such that the rotating cam member 21 rotates counterclockwise, the first movable coil member 7 further moves leftward or rightward due to the same action as described above. move the pin 7b to the cam surface 25c.
Alternatively, the position of the photographing lens 9 can be regulated by bringing it into contact with 25f.

Furthermore, when the photographing is finished and the energization to the second movable coil member 8 is canceled, and the energization to the first movable coil member 7 is performed in the opposite direction to that during focusing, the second movable coil member 8 Since the biasing force that moved the pin 7b disappears, the rotary cam member 21 is restored to the balanced state shown in FIG.
and 25d.

In addition, since the pin 7b of the first movable member 7 is interposed between the cam surfaces 25a and 25d of the cam portion 25 of the rotary cam member 21 when it is not in operation, the photographing lens 9 can be moved between the cam surfaces 25a and 25d. 25
When trying to regulate the position corresponding to d,
The photographing lens 9 can be set to the focusing position only by the operation of the first movable coil member 7, and as a result, in the photographing lens driving device according to the present invention, the photographing lens 9 is moved to the cam portion 25.
The cam surfaces 25a to 25f make it possible to perform focusing operations on a plurality of points, three points in the front and rear, for a total of six points.

FIG. 6 shows another embodiment of the present invention incorporating a between-type shutter unit 50, which has exactly the same functions and effects as the previous example and has the same effects.

〔Effect of the invention〕

The present invention provides a first movable coil member that is provided integrally with a photographic lens and moves the photographic lens forward or backward in the optical axis direction when energized; a second movable coil member that moves rearward is disposed within a gap of a magnetic circuit made up of a pair of magnetized members formed around the optical axis of the photographing lens;
an engaging member provided on the first movable coil member; and a cam member having a cam rotatably pivoted by movement of the second movable coil member and abuttable by movement of the engagement member; , a holding member that holds the initial position of the cam member, and rotates the cam member when the second movable coil member is energized based on a signal from a distance measuring device that measures the distance to a subject; The photographing lens is driven by energizing the first movable coil member, and the stopping position of the photographing lens is determined by the engagement member coming into contact with the cam of the cam member. , since the cam member rotates to the left or right from the middle point (initial position) by energizing the second movable coil member, it can take three positions including the middle point where no current is applied. Since the first movable member moves forward or backward when the first movable member is energized, the number of points at which the engaging member contacts the cam of the cam member is six in total, and the structure is simple and reliable. It became possible to determine the lens stop position in six stages. In addition, since the photographing lens is always focused at a position on the circumference, optical precision is high, and since it moves from the midpoint position to the far point or near point, the moving distance is short and focusing operations are speeded up. It also has the following.
We have now provided an excellent camera lens drive device.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of the photographic lens driving device of the present invention. Figure 2 is a cross-sectional view taken along arrow AA. 3 and 4 are main part diagrams of the device. Figure 5 is a cross-sectional view taken along arrow BB. FIG. 6 shows another embodiment. 1... Lens barrel body, 2... Permanent magnet, 3, 4...
Yoke, 3a... Inner ring part, 4a... Outer ring part, 5, 5
0... Shutter unit, 7... First moving coil member, 8... Second moving coil member, 7a, 8a...
...Coil pattern, 7b, 8c, 24a, 24b
...Pin, 9...Photographing lens, 10...Mirror frame, 2
DESCRIPTION OF SYMBOLS 1... Rotating cam member, 21a, 21b... Standing part, 22... Support shaft, 23... Torsion spring, 25...
Cam portion, 25a to 25f...cam surface.

Claims (1)

[Claims] 1. A first movable coil member that is provided integrally with the photographic lens and moves the photographic lens forward or backward in the optical axis direction when energized; a second movable coil member disposed in a gap of a magnetic circuit made up of a pair of magnetized members formed around the optical axis of the photographing lens, and an engaging member provided on the first movable coil member; A cam member having a cam rotatably pivoted by movement of the second movable coil member and abuttable by movement of the engagement member, and a holding member that holds the initial position of the cam member. , the cam member is rotated when the second movable coil member is energized based on a signal from a distance measuring device that measures the distance to the subject, and then the first movable coil member is energized to 1. A photographing lens driving device, characterized in that the photographing lens is driven and the engaging member comes into contact with a cam of the cam member to determine a stop position of the photographing lens.