JP4653424B2 - Image blur prevention device - Google Patents

Description

  The present invention relates to an optical image stabilizer, and more particularly to a structure of an image shake preventer installed in a lens barrel in order to correct image vibration.

  The mechanism that moves some of the correction lenses that make up the photographic lens in the direction perpendicular to the optical axis predicts image blur, for example, by detecting the camera shake acceleration that causes image blur in the camera. Based on the above, there has been proposed a vibration isolator that suppresses image blur by moving the lens in a right angle direction.

  Various methods have been proposed for these anti-vibration devices, but the mechanism must be capable of correcting and moving the correction lens in the direction perpendicular to the optical axis in any vibration direction. A guide shaft is provided radially from three locations on the side surface of the frame, and is inserted into each of three guide grooves provided on the side surface of the vibration isolator body so that the correction lens barrel can be corrected and moved in all directions. A structure is disclosed in which the lens frame is suspended by coil springs urged from three sides of the main body so that the lens frame can be held at the center of the optical axis, and the combined force acting on the two moving coils for movement in the X and Y directions is disclosed. A system has been proposed for determining the movement perpendicular to the optical axis by an amount determined by the difference in elastic drag of the spring, but in order to hold the correction lens frame perpendicular to the optical axis, Guide of fixed part The need to increase the fitting accuracy, therefore the friction occurring between the shaft and the groove resistance increases to, and hinders rapid vertical movement.

  In order to reduce the frictional resistance at the time of movement, the fitting accuracy between the guide shaft and the groove of the correction lens barrel is loosened and it is desired to move freely, but this is not preferable because the vibration at the time of movement affects the correction accuracy. For this reason, there has been proposed a method in which the holding surface is applied by the component force of the biasing spring that keeps the correction lens frame on the optical axis so as to keep the accuracy of the plane perpendicular to the optical axis of the correction lens frame toward one side. Has no effect of reducing frictional resistance because pressure is applied to the holding surface.

As an improvement measure, the applicant supports a correction lens frame with a single hinge shaft so that it can tilt in all directions, and a structure that can be moved in all directions is disclosed in Japanese Patent Application Laid-Open No. 2003-307761. Proposed in open 2004-177530. Both ends of the hinge shaft are spheres or sphere-shaped, and have a structure that receives them at both ends as shown in FIG. 2, which is far more than the conventional structure that slides on the friction surface. Lightweight when moving.
Japanese Patent Laid-Open No. 10-026784 Japanese Patent Laid-Open No. 10-003102 JP 2003-307761 A JP 2004-177530 A

  The problem to be solved is that a single hinge shaft structure of the above-mentioned Japanese Patent Application Laid-Open Nos. 2003-307761 and 2004-177530, which is a conventional example, uses a spherically shaped shaft end so that it can tilt in all directions. However, in manufacturing, there is a difficulty in processing the shaft including the spherical processing of the terminal, and in particular, there is a problem in that the manufacturing cost is proportional to increasing the roundness accuracy of the spherical shape at both ends.

  In the present invention, the shape of the hinge shaft of a conventional spherical terminal is divided into one shaft that is easy to process and a commercially available steel ball, and the shaft is sandwiched by two steel balls from both ends, and the steel ball is received. It is possible to tilt the shaft in all directions by mounting it between the ball bearings at both ends, and further, a coil spring with the shaft as a core is stretched between the ball bearings, and the shaft is moved by the contraction pressure of the coil spring. The problem was solved by making it possible to hold it between the steel balls at both ends. That is, a ball is installed in the receiving part of the support frame and the receiving part on the fixed part side, and the shaft is sandwiched between the two balls, and the coil spring is contracted with both ends fixed to the receiving part. The ball and the shaft are held by the force, and the shaft can be tilted in all directions, and the correction lens is given a habit of returning to the optical axis position with respect to the movement in all directions. Furthermore, both the receiving portion of the support frame of the correction lens and the receiving portion on the fixed side are formed with a cylindrical tip on the male screw, and the coil spring installed between them has an inner diameter substantially the same as the valley diameter of the male screw. The both ends of the coil springs are fixed to the front ends of the two receiving portions, and the contraction biasing force of the coil spring can be adjusted by the rotation of the two receiving portions.

  In an image shake apparatus that supports a correction lens that is moved eccentrically for image shake correction and a fixed holding frame by a single hinge shaft and performs correction by tilting in all directions. While it is easy to process and assemble the hinge shaft, the contraction pressure is generated by the coil spring stretched between the two ball holders to prevent the steel balls from falling off. Habitual elasticity to return to the shaft position is obtained, and quick response is guaranteed.

  Hereinafter, the best embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of an embodiment of the apparatus of the present invention. FIGS. 2a and 2b are operation explanatory views of an omnidirectional tilting hinge shaft, and FIG. 3 is a perspective view of an image shake preventing apparatus of the present invention. Yes.

  The image blur prevention device is a mechanism that shifts the correction lens 2 from the optical axis 1 by a necessary distance in a necessary direction to correct the fixed portion in the lens barrel in accordance with vibration. A holding mechanism that can move the lens 2 with respect to the optical axis 1 of the fixed part and a mechanism that can smoothly move the lens 2 in all directions perpendicular to the optical axis 1 without rotation are required. For this reason, the inventor proposed the embodiment of FIG. 3 showing the entire configuration in the prior patent (Japanese Patent Application No. 2002-341616) and adopted it in this image blur prevention apparatus.

  The overall configuration of the image shake prevention apparatus shown in FIG. 3 will be described with reference to FIG. 1. FIG. 3 shows a fixed holding frame 3 fixed to the lens barrel and a presser plate 6 attached from the back. It is divided into a support frame 4 that holds the lens 2 and is movable in all directions.

  A lower yoke 10 to which a Y-drive magnet 11 and an X-drive magnet 12 that are plate-shaped counter magnets are arranged and fixed at right angles is fixed to a hollow annular holding frame 3 around the optical axis 1. A large through-hole 3a is opened at a position corresponding to an approximately intersection of the YX drive magnets 11 and 12 disposed in the guide, and a guide receiver 13 is fixed at a position facing the hole 3a with the optical axis 1 interposed therebetween. As shown in the figure, the guide receiver 13 has linear motion gears at both ends, which are a left rack 13e and a right rack 13f. It is molded in one piece.

On the other hand, a Y drive coil 15 and an X drive coil 16 are arranged at right angles to the support frame 4 that supports and fixes the correction lens 2 at the center as shown in the figure, and will be described in detail later at a position corresponding to this orthogonal point. There is a receiving portion 9 for receiving the hinge shaft 7 and the ball 7a. A guide bearing 5 is provided on the vertical line passing through the optical axis 1 with respect to the receiving portion 9 and installed horizontally, and has slide holes 5a and 5b. The guide shaft 17 is provided on the guide bearing 5. In contrast, rotation and sliding are possible. The guide bearing 5 is installed between the bearing portion 13 a and the bearing portion 13 c of the guide receiver 13 fixed to the holding frame 3, the guide shaft 17 passes through the long hole 13 d, and the slide hole 5 b of the guide bearing 5 extends from the slide hole 5 b. The long hole 13b of the bearing portion 13a of the guide receiver 13 is passed through 5a. A right pinion 19 and a left pinion 18 are fixed to both ends of the guide shaft 17, and the right pinion 19 meshes with the right rack 13f and the left pinion 18 meshes with the left rack 13e.

  The left and right pinions 18 and 19 roll while meshing with the left and right racks 13e and 13f, so that the guide shaft 17 can move in parallel without swinging in the long holes 13b and 13d of the guide receiver 13, so Since the frame 4 can be accurately moved in the vertical direction with respect to the optical axis 1 and the guide bearing 5 of the support frame 4 can slide to the left and right with respect to the guide shaft 17, the support frame 4 is perpendicular to the optical axis 1. Can be moved to. The movements according to these two guides are perpendicular to each other, and in all directions due to the combined drive force of the Y drive coil 15 and the X drive coil 16 fixed integrally with the holding frame 3 of the correction lens 2. Quantitative movement is possible.

  As a method for generating the driving force of the Y driving coil 15 and the X driving coil 16, a predetermined gap is maintained above the Y driving magnet 11 and the X driving magnet 12 which are installed on the holding frame 3 and fixed to the lower yoke 10 as described above. The upper yoke 14 is installed, and the magnetic lines of force generated in the gap draw a closed loop by the Y and X drive magnets 11 and 12, but the surface of the Y and X drive magnets 11 and 12 are above the gap. The Y drive coil 15 and the X drive coil 16 of the support frame 4 are inserted and maintained at a position where a slight gap can be maintained between the surface of the yoke 14.

  In a state where the optical axis of the correction lens 2 and the optical axis 1 of the lens barrel coincide with each other, each coil side of the Y drive coil 15 at the magnetic pole opposing position of the Y driving magnet 11 and each of the coil sides of the X driving magnet 12 at the magnetic pole opposing position. Since each coil side of the X drive coil 16 is accurately covered while maintaining a slight gap, the X drive coil 16 is generated in the gap in the magnitude and direction in which a current flows through the Y drive coil 15 and the X drive coil 16. A driving force that moves inward or outward with respect to the optical axis 1 is generated by electromagnetic action with the magnetic field lines. Since each of the Y drive coil 15 and the X drive coil 16 is at a position opened 90 degrees, the drive directions are 90 degrees different from each other, and any direction movement for camera shake correction is the same as the direction of the Y drive coil 15 and the X drive coil 16. It is obtained by a combined vector of driving forces.

Since the support frame 4 including the correction lens 2 needs to respond with a correction amount necessary for preventing camera shake at a high speed synchronized with the camera shake operation, sliding friction in the support must be avoided as much as possible.
Therefore, in this apparatus, as shown in FIG. 3, a hinge shaft 7 that can be tilted in all directions is installed at a position corresponding to the apex of the triangle with the guide shaft 17 as a base, and the support frame 4 is fixed to the holding frame 3 on the fixed side. And the method of supporting with respect to the pressing plate 6 is adopted to avoid contact with the fixed side when the support frame 4 is moved.

  A sectional view of the optical axis 1 including the hinge shaft 7 is shown in FIG. 1. As clearly shown here, the hinge shaft 7 has a concave shape in which the centers of both ends are tapered, and the balls 7a and 7b are The ball 7 a is held between the left end of the hinge shaft 7 and the receiving portion 9 having the same center shape as both ends of the hinge shaft 7, and the ball 7 b has the same center shape as both ends of the hinge shaft 7. It is held between the receiving part 8, the receiving part 8 is installed on the fixed holding plate 6 side, and the receiving part 9 is installed on the movable supporting frame 4 side. A shape that supports the support frame 4 is constituted by the hinge shaft 7 penetrating 3a, and the space between the holding frame 3 and the support frame 4 is maintained at a constant interval. The hinge shaft 7 can be freely tilted in all directions with respect to the holding frame 3 on the fixed side by the balls 7a and 7b, and an extremely light operation can be obtained. FIG. 2A is a diagram showing this principle operation. In FIG. 2A, the optical axis of the correction lens 2 coincides with the optical axis 1 of the fixed-side lens barrel, and the uncorrected state is upright of the hinge shaft 7 indicated by a solid line. This is a state position, which indicates that the movement direction and the movement amount necessary for correcting the correction lens 2 can be obtained by tilting in all directions.

  In order to hold the hinge shaft 7 between the ball 7b of the receiving portion 8 and the ball 7a of the receiving portion 9, it is impossible to maintain the state by simply stacking the components, and there is a risk that each component is dispersed depending on the posture. Since the present invention has solved this with a simple structure, the configuration centered on the hinge shaft 7 will be described in detail below. As shown in the sectional view of FIG. 1, the shapes of the receiving portion 8 and the receiving portion 9 are centered. Recessed ball 7a. 7b can be received, cylindrical portions 8c and 9c are formed at intervals around the outer periphery, and the outer shape thereof is formed in the shape of a male screw having peaks and valleys of the same pitch, and has substantially the same shape. Yes. The shape of the male screw of the receiving portions 8 and 9 is closely related to the shape of the coil spring 20 installed between the receiving portions 8 and 9, and if the male screw is a right-hand screw, the coil spring 20 is right-handed. For left-handed screws, it is essential to use a left-handed spring.

  The receiving portion 8 is fitted into the hole 6a of the holding plate 6 so that it cannot be pulled out by the collar 8b of the receiving portion 8, and the other receiving portion 9 is also fitted into the hole 4a of the support frame 4 and cannot be pulled out by the collar 9b. On the other hand, the receiving portions 8 and 9 can be turned with reference to the holes 6a and 4a by the slits 8a and 9a of the head. The shape of the coil spring 20 installed between the receiving portions 8 and 9 is designed to be substantially the same as the valley diameter of the cylindrical portions 8 c and 9 c of the receiving portions 8 and 9 and the inner diameter of the coil spring 20. It can be screwed to the threaded portions of the cylindrical portions 8c and 9c of the receiving portions 8 and 9 with respect to both ends of 20.

  When the parts machined in the above shape are assembled in order, the cylindrical part 8c of the receiving part 8 is machined into a right-hand thread with respect to the right-handed coil spring 20, so that the slot 8a on the head is moved to the right. The tip of the coil spring 20 can be screwed deeply while being screwed into the threaded portion of the cylindrical portion 8c. In this state, the ball 7b is placed at the center of the receiving portion 8 and the hinge shaft 7 is installed so as to be the center of the coil spring 20, and the ball 7a is placed on the other end of the hinge shaft 7 and further the support frame 4 is placed thereon. Covering the receiving portion 9 installed in the center to receive the ball 7a and turning the slot 9a of the head clockwise, the tip of the coil spring 20 is screwed into the right-hand thread portion of the cylindrical portion 9c, and the depth is increased depending on the number of turns. Even if it is shallow, it can be arbitrarily screwed.

  As a result of assembling as shown in FIG. 1, the hinge shaft 7 and balls 7 a and 7 b are placed at both ends at the center, and the shape sandwiched by the receiving portions 8 and 9 from both ends is placed at the center and wrapped with the coil spring 20. Although both ends of the coil spring 20 are screwed into the threaded portions of the cylindrical portions 8c and 9c, the coil spring 20 is extended, and the receiving portion 8 passes through the balls 7a and 7b around the hinge shaft 7. The contraction pressure is applied from the receiving part 9. As a result, the balls 7a and 7b are held at both ends with the hinge shaft 7 as the center, and the shape in which the balls 7a and 7b are held between the receiving portion 8 and the receiving portion 9 can be maintained, and the components can be prevented from being dispersed due to the posture. The contraction pressure by the coil spring 20 between the receiving part 8 and the receiving part 9 changes the depth at which both ends of the coil spring 20 are screwed into the cylinders 8c, 9c by adjusting the slits 8a, 9a of the head. The strength can be adjusted.

  The state shown in FIG. 1 shows a state before the camera shake correction operation in which the optical axis 1 and the optical axis of the correction lens 2 coincide with each other, and the hinge shaft 7 is in an upright posture with respect to the holding frame 3 on the fixed side. The coil spring 20 is also free from bending. However, as shown in FIG. 2B, the hinge shaft 7 is inclined by α ° with respect to the movement amount γ of the support frame 4 necessary for correction, and the coil spring 20 is bent as shown in FIG. The resilience to is generated. FIG. 2B shows an example in which the support frame 4 is moved to the right with respect to the holding frame 3 on the fixed side. However, the support frame 4 is actually applicable to all directions and bends to the coil spring 20 in any direction and amount of movement. Accordingly, a restoring force to the upright posture is applied in accordance with this, and a returning behavior is provided in which the optical axis of the correction lens 2 returns to a position that matches the optical axis 1 of the lens barrel. The return habit with the speed characteristic of the correction lens 2 to the optical axis 1 and the restoring force at the time of correction must match the appropriate correction characteristics that match the respective lens characteristics. In addition to the advantages that can be easily obtained by adjusting the rotation of the bearing 8 and the receiving part 9, the industrial value that the important parts can be composed of commercially available parts or simple processed parts is great.

  In an industrial product having a structure in which a single shaft approximating to a joystick can be tilted in all directions, when it is desired to give a return habit to the upright position of the shaft, the shaft is used as a core as in the present invention. This can be easily solved by inserting a coil spring between the bearings.

It is sectional drawing of the image blurring prevention apparatus of this invention. It is operation | movement explanatory drawing of a hinge shaft. It is a perspective view of an image shake prevention apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical axis 2 Correction lens 3 Holding frame 4 Support frame 5 Guide bearing 6 Holding plate 7 Hinge shaft 8 Receiving part 9 Receiving part 10 Lower yoke 11 Y drive magnet 12 X drive magnet 13 Guide receiver 14 Upper yoke 15 Y drive coil 16 X Drive coil 17 Guide shaft 18 Left pinion 19 Right pinion 20 Coil spring

Claims (2)

A correction lens installed in the lens barrel and decentering the optical axis; vibration detection means for detecting vibration applied to the lens barrel; and driving the correction lens based on a signal obtained from the vibration detection means ; An image blur prevention apparatus including a control unit for preventing image blur, wherein the correction lens can be moved in all directions around the optical axis by drive mechanisms in a first direction and a second direction which are perpendicular to each other. In the correction lens moving mechanism, which is supported by a tilting operation in all directions of the shaft, the support frame of the correction lens of the correction lens moving mechanism is pivotally supported by a single shaft with respect to the fixed portion. Each ball is installed in the receiving part on the fixed part side, and the shaft is sandwiched between the two balls, and the ball and the shaft are held by a contraction biasing force of a coil spring fixed at both ends to the both receiving parts. And A possible omnidirectional tilting operation of the shaft, the correction lens with respect to omnidirectional image blur prevention apparatus is characterized in that given a habit of returning to the optical axis position.   Both the receiving part of the support frame of the correction lens and the receiving part on the fixed side are formed with a cylindrical tip at the male screw, and the coil spring installed between them is formed with an inner diameter that is substantially the same as the valley diameter of the male screw. The both ends of the coil springs are fixed by screwing them to the tips of the receiving parts, and the contraction biasing force of the coil spring can be adjusted by the rotation of the receiving parts. The image blur prevention apparatus according to claim 1.

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