JPH0157887B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a photographic lens driving device that drives a photographic lens unit for focusing operation using electromagnetic force.

With the miniaturization of cameras and the spread of retractable cameras in which the photographic lens barrel can be stored inside the camera body, the shutter mechanism, photographic lens drive mechanism, and It has become difficult to drive various drive mechanisms such as the film winding mechanism due to installation space limitations. That is, in order to obtain the necessary output from such a drive source, the shape of the drive source itself must be large, and the power transmission mechanism must also be complicated, making it impossible to accommodate it in a small space. In particular, in retractable cameras, the taking lens barrel moves in and out of the camera body, making the power transmission mechanism to the taking lens drive mechanism even more complex and requiring a large installation space.

Therefore, in recent cameras, there is a tendency to downsize the drive source itself and simplify or eliminate the power transmission mechanism by using an electromagnetic drive device for each mechanism.

However, conventional electromagnetic drive devices used for focusing operations on photographic lenses are based on the premise of narrowing the gap between opposing fixed permanent magnets and reducing loss in the magnetic circuit. In this case, one movable coil member is arranged, and the photographing lens unit is driven by this movable coil member. Therefore, it is only possible to select two-step control in two directions depending on the direction of the applied current, that is, from infinite distance to close distance, and from close distance to infinite distance, and it is not possible to move the photographing lens in multiple steps. 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, and an electromagnetic The 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. It was also extremely difficult to realize.

This invention is intended to solve the above problem, and uses a simple structure in which a plurality of moving coil members are arranged around a lens so as to cross the magnetic flux of a magnetic circuit formed by fixed permanent magnets. It is an object of the present invention to provide a photographic lens driving device that enables forward and backward movement of a photographic lens unit and control of the amount of movement thereof.

Next, the present invention will be described based on embodiments shown in the accompanying drawings.

Reference numeral 1 denotes a photographic lens barrel, and a cylindrical yoke 2 is attached to a retaining ring 3 on the inner surface of the base of the photographic lens barrel 1.
It is fixed by. The yoke 2 is provided with a concave groove 4 on its tip surface, and an inner ring part 2a and an outer ring part 2b are formed sandwiching the space of the concave groove 4.

Reference numerals 5 and 6 denote fixed permanent magnets arranged in a cylindrical shape on the outer surface of the inner ring portion 2a and the inner surface of the outer ring portion 2b of the yoke 2, respectively, and the fixed permanent magnets 5 and 6 are held in cylindrical holding frames 5a and 6a. has been done. The fixed permanent magnets 5 and 6, which face each other on the inside and outside, have opposite polarities on their opposing surfaces and form a magnetic circuit. In this embodiment, this magnetic circuit is formed by directly facing the fixed permanent magnets 5 and 6, but in addition to this, it is possible to form a fixed permanent magnet and a joint magnetized by the fixed permanent magnet. Even if formed by confronting iron,
Alternatively, the yoke may be formed by opposing yokes magnetized by fixed permanent magnets. Reference numerals 7 and 8 denote cylindrical moving coil members having coil patterns 7a and 8a on their outer peripheral surfaces, and the moving coil members 7 and 8 are disposed between the fixed permanent magnets 5 and 6.

One movable coil member (hereinafter referred to as the first movable coil member) 7 is for driving the lens barrel 10 into which the rear lens groups 9a and 9b are fitted, and the other movable coil member (hereinafter referred to as the second movable coil member) A coil member 8 is used to control the amount of movement of the first movable coil member 7.

The first movable coil member 7 is integrally fixed to a flange portion 10a provided on the outer surface of the distal end of a lens frame 10, and the lens frame 10 is fixed to a flange portion 10a provided along the inner circumference of the yoke 2. It is provided on a ball bearing 11 disposed in the portion 2a' so as to be movable back and forth via a guide groove 12, and in the normal state, the spring 1
3, it is pressed forward (to the left in the figure).

Depending on the configuration of the guide groove 12, the lens barrel 10 may move back and forth in a linear manner, or may move back and forth in a spiral manner, and it may be freely determined which of these is adopted. However, in the case where the lens barrel 10 is moved back and forth linearly and when it is moved back and forth spirally, the coil 7a of the first movable coil member 7 is
Naturally, the way of wrapping is different. In the former case, the coil 7a is wound along the circumferential direction of the first movable coil member 7 as shown in the third figure, and in the latter case, the coil 7a is wound in a spiral shape (or wave shape) as shown in the fourth figure. As a means for winding the pattern into a shape, the pattern may be formed in advance on a flexible printed circuit board and then bonded with an adhesive.

The second movable coil member 8 is held by a retaining ring 14 so as to be rotatable about the inner ring portion 2a of the yoke 2 into which a wheel 8b provided at one end is fitted. The coil pattern 8a of the second moving coil member 8 is wound in a spiral shape (which may be wavy) as shown in FIGS. It is advantageous to use flexible printed circuit boards as well.

Reference numeral 15 indicates a step-like structure (three steps in the figure) provided at the outer end of the first moving coil member 7.
This number of stages is not limited. ), and the cam groove 15 engages with a protrusion 16 provided at the other end of the second movable coil member 8. 17 is the protrusion 1
6 is a spring member for regulating the initial position of the second movable coil member 8 so that it is located at the midpoint 15a of the cam groove 15, and the spring member 17 is formed in a U-shape in the drawing. The bent side 17a is connected to the yoke 2
and fix the free end sides 17b, 17b' to the protrusion 1.
It is locked in locking parts 18a and 18b recessed on both sides of 6. Therefore, when the second movable coil member 8 is not energized, due to the spring force of the spring member 17,
Its initial position is maintained, and when energized, it rotates to the right or left from the initial position in response to a signal from a lens drive circuit, which will be described later. Since this rotation is performed against one free end 17b or 17b' of the spring member 17, when the energized state is removed, the spring force returns the spring member to its initial position. This second movable coil member 8 has a protrusion (not shown) provided at a proper location and a stopper (not shown) provided on the yoke 2.
The selected position, that is, the position corresponding to the stepped portion of the cam groove 15 of the first movable coil member 7 is held by hitting the same.

In the figure, 19 is a spacer between the rear lens groups 9a and 9b, 20 is a retaining ring for the rear lens groups 9a and 9b, and 21 is a retaining ring for the ball bearing 11.

Reference numeral 22 denotes a lens frame into which the front lens groups 23a and 23b are fitted, and on the outer periphery of the lens frame 22, an aperture shutter blade 24 is driven which is disposed between the lens frame 10 of the rear lens groups 9a and 9b. An electromagnetic drive device 25 is provided for this purpose. This electromagnetic drive device 25 faces a fixed permanent magnet 27 which is attracted and held by a disk-shaped yoke 26 fitted to a lens barrel 22 and is spaced apart from a fixed permanent magnet 27 via a holding frame 28 of the fixed permanent magnet 27. A driving movable coil member 30 for driving the aperture shutter blade 24 and a control movable coil member 31 for controlling the amount of movement of the driving movable coil member 30 are provided between the yoke 29 and the yoke 29. , it is possible to operate a predetermined opening diameter in a predetermined time. 32 is a retaining ring for the front lens groups 23a and 23b, and 33 is a decorative ring.

FIG. 6 is a block diagram showing an electric circuit. When the release button (not shown) is pressed, the information input circuit 34 is activated, and when film sensitivity information, shooting mode information, etc. are input to the CPU 35, photometry is performed. Exposure value information is input to the CPU 25 by the circuit 36,
Distance information is input from the distance measuring circuit 37 to the CPU 35. In the CPU 35, when exposure value information and distance information are calculated based on the photographing mode information etc. by the information input circuit, an aperture control signal, a drive signal, and a current direction signal are inputted to the electromagnetic drive device 25 of the aperture shutter blade 24 to electromagnetically drive it. Moving coil members 30 and 31 of device 25 are energized. Similarly, a lens control signal, a lens drive signal, and a current direction signal are input to the lens drive circuit 38, and the movable coil members 7 and 8 are energized, and the aperture is stopped in the sequence shown in the time chart shown in FIG. The shutter blade 24 and the lens frame 10 of the rear lens group are operated. That is, when the position of the lens is determined by the CPU 35, the current direction in which the coil 8a of the second movable coil member 8 should be energized is determined, and the current direction signal is input to the drive circuit 38, which then controls the lens. A signal is generated and the coil 8a of the second movable coil member 8 is energized. After this energization, the direction of current to be energized to the coil 7a of the first moving coil member 7 is determined, and the current direction signal is energized to the coil 7a of the first moving coil member 7 through the drive circuit 38. .

In FIG. 7, t ₁ , t ₂ , and t ₃ represent respective time lags, T represents shutter seconds, and A to F represent forward/reverse current and non-energized state.

Next, the effect will be explained.

As mentioned above, when the release button (not shown) is pressed and the distance measurement signal is transmitted from the pathfinding circuit 37 to the CPU 35 and the stop position of the lens is determined, a control signal is transmitted to the drive circuit 38. An electromagnetic direction signal suitable for the direction of operation of the second moving coil member 8 is also input to the drive circuit 38 to maintain the second moving coil member 8 in its initial position or to rotate it to the right or left from its initial position. Depending on whether this second moving coil member 8 is at the initial position, or to the right or left of the initial position, the protrusion 16 is located at the midpoint of the stepped cam groove 15 of the first moving coil member 7 or at the deep groove 1.
5b or the shallow groove 15c. Subsequently, the coil 7 of the first movable coil member 7
When the first movable coil member 7 is energized and moves straight (the same applies when it moves spirally), it starts to move rightward in the figure against the biasing force of the spring 13, and the cam groove 15 One of the step portions engages with the protrusion 16 of the second movable coil member 8.

Thus, the amount of movement of the first movable coil member 7 is controlled by the depth of the cam groove 15 corresponding to the protrusion 16. The amount of movement of the first movable coil member 7 determines the amount of movement of the lens barrel 10 into which the rear lens groups 9a and 9b are fitted, and a focusing operation is performed. For example, the cam groove 15 of the first moving coil member 7
If the configuration is such that the midpoint 15a is a common focal point, the deep groove 15b is focused at a close distance, and the shallow groove is focused at an infinite distance, the position of the protrusion 16 of the second moving coil member 8 The photographic lens is operated to focus in three stages: common focus, close range, and infinity.

In this way, when the position of the lens is determined, the movable coil members 30, 3 of the shutter drive circuit 25
1 is energized, exposure control is performed, and the shutter is turned off.

In the above embodiment, the shutter device 24 is fixed to the lens frame 22 of the front group of the photographic lens optical system, and only the lens frame 10 into which the rear lens groups 9a and 9b are fitted is attached to the first movable coil member 7. However, depending on the magnitude of the electromagnetic force, it goes without saying that the entire photographic lens unit may be driven.

Further, in the above embodiment, the first movable coil member 7 is pressed forward (to the left in the figure) by the spring 13, and when energized, moves backward (to the right in the figure) against the spring 13. However, the pressing direction of the spring 13 may be the opposite, and the relationship between the cam groove 15 and the protrusion 16 may be such that the relative positions of the first and second moving coil members 7 and 8 can be maintained. If provided, the locations are not limited to those shown in the drawings, and the protrusions 16 may be formed on the first moving coil member 7 and the cam grooves 15 may be formed on the second moving coil member 8.

Furthermore, the step-like cam groove 15 provided in the first movable coil member 7 for driving the photographic lens unit is formed into an array-like transparent structure having wide width parts b and c of different widths at both ends of the narrow width part a, as shown in FIG. Instead of hole 15',
A second movable coil member 8 is inserted into the arrayed through holes 15'.
It is also possible to configure the movable amount of the first movable coil member 7 to be adjustable in six stages by engaging the protrusions 16 of the first movable coil member 7. That is, in this case, if the protrusion 16 of the second movable coil member 8 is located in the narrow width part a of the array-shaped through hole 15', then the protrusion 16 is located in the narrow area between the two points A and B before and after it. If the movable amount of the movable coil member 7 is adjusted and the protrusion 16 is located at the intermediate wide portion b of the through hole 15', the movable amount is adjusted between the two points C and D before and after the protrusion 16. If the protrusion 16 is located at the widest part c of the through hole 15', the amount of movement will be adjusted between the two points E and F before and after it.

The array of through holes 15' corresponds to the position of the photographing lens from infinity to close range between the facing surfaces E and H of the maximum width part c, so that fine control can be performed in six stages from A to F. is now possible. Therefore, according to this embodiment, by focusing the positions A and B of the narrow width part a at the common focal point and a position near the common focal point, the brightness of the field can normally be changed when the sky is clear, etc. It has a short distance and has excellent power saving effects, and by adding a mechanism (for example, a spring balance) that holds the photographic lens at the midpoint of its movement range, seven-step control is possible, which is not possible with conventional electromagnetic drive devices. This has the advantage that multi-step control, which was previously unavailable, can be achieved with a simple mechanism.

In this way, according to the present invention, so as to cross the magnetic flux of the magnetic circuit formed by the fixed permanent magnet,
In addition, since it is characterized by being composed of a plurality of movable coil members disposed around the lens, at least one of the movable coil members is used as a driving movable coil member for driving the photographing lens unit, and the other By using the movable coil member to control the amount of movement of the driving movable coil member,
This provides an excellent effect in that the forward and backward movement of the photographic lens unit can be easily controlled in multiple stages.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and Fig. 1 is a central vertical sectional view, Fig. 2 is a sectional view showing the arrangement of fixed permanent magnets, and Figs. 3 and 4 are coil patterns of the first movable coil member. FIG. 5 is a relational diagram between the first moving coil member and the second moving coil member showing the second control method of the present invention. FIG. 6 is a block diagram of the electric circuit. Figure 7 is a time chart. 5, 6...Fixed permanent magnets arranged in a cylindrical shape, 7...
...driving moving coil member (first moving coil member),
8... Control movable coil member (second movable coil member).

Claims (1)

[Claims] 1 A first movable coil member provided integrally with the photographing lens unit so as to move the photographing lens unit in the optical axis direction when energized, and a second movable coil member provided so as to rotate around the optical axis of the photographing lens when energized. The coil member is arranged in one gap of a magnetic circuit formed by fixed permanent magnets around the optical axis of the photographic lens, and one of the first movable coil member and the second movable coil member is arranged in a direction around the optical axis. An abutting surface having a different surface position in the optical axis direction for each position is provided with an abutting portion that abuts the abutting surface on the other side, and the contact portion is provided to contact the first movable coil member and the second movable coil member based on a signal from the distance measuring device. The first movable coil member is moved relative to the second movable coil member whose movement amount is changed in the rotational position direction by the control means for controlling the energization of the member, and the abutting portion is abutted against the abutting surface, and the distance measuring device is moved. An imaging lens driving device characterized in that it is configured to determine a stop position of a lens in an optical axis direction based on a signal.