MICRO SUSPENSION DEVICE AND SPRING FOR A MICRO SUSPENSION DEVICE

Abstract

A micro suspension device includes a base and a carrier that is designed to move relative to the base along a reference axis. The carrier is suspended and guided relative to the base by a spring arrangement. The spring arrangement has two spring units, each spring unit has two arms, and each of the arms has first and second sections and a connection node. The first section extends from a first attachment node, attached to the base, to the connection node. The second section extends from the connection node to a second attachment node attached to the carrier. In each spring unit the arms are connected at their connection nodes, are mirror-symmetric to one another, and are angled relative to one another.

Claims

1. A micro suspension device, comprising a base and a carrier that is designed to move relative to the base along a reference axis, wherein: the carrier is suspended and guided relative to the base by a spring arrangement, the spring arrangement comprising at least a first spring unit and a second spring unit, each of said first and second spring units comprising a first arm and a second arm, each arm comprising a first section, a second section, and a connection node, the first section extending from a first attachment node, at which the first section is attached to the base, to the connection node, the second section extending from the connection node to a second attachment node at which the second section is attached to the carrier, wherein the first attachment node and the second attachment node lie at a same circumferential position on the base and carrier, respectively, wherein in each spring unit, the connection node of the first arm is connected to the connection node of the second arm, the first arm and second arm are mirror-symmetric to one another, and the first arm and second arm are angled relative to one another.

2. The micro suspension device of claim 1, wherein the first arm and second arm are mirror-symmetric to one another, with respect to a mirror plane comprising the connection node and the reference axis.

3. The micro suspension device of claim 1, wherein, when the carrier is moved relative to the base in the direction of the reference axis, a distance between the connection nodes of the spring units and the reference axis changes according to this relative movement.

4. The micro suspension device of claim 1, wherein the arms form sections of a circle centred on the reference axis.

5. The micro suspension device of claim 1, wherein the sections of the first arm are parallel to a first side of a triangle, the sections of the second arm are parallel to a second side of the triangle, and a first line connecting the first attachment nodes of the first arm and the second arm and a second line connecting the second attachment nodes of the first arm and the second arm are parallel to a third side of the triangle.

6. The micro suspension device of claim 1, wherein the first spring unit and the second spring unit have congruent shapes and are arranged in a mirror symmetric arrangement.

7. The micro suspension device of claim 1, wherein the first attachment node of the second arm of the first spring unit coincides with or is identical to the first attachment node of the first arm of the second spring unit, and the second attachment node of the second arm of the first spring unit coincides with or is identical to the second attachment node of the first arm of the second spring unit.

8. The micro suspension device of claim 1, comprising exactly two spring units which together extend around at least a third of the circumference of the carrier, in particular around half the circumference.

9. The micro suspension device of claim 1, comprising exactly four spring units which together extend around at the entire circumference of the carrier.

10. The micro suspension device of claim 1, wherein there exists a planar configuration of the spring arrangement in which the arms lie in a plane.

11. The micro suspension device of claim 10, wherein the spring arrangement is either manufactured from a single piece of a flat material, in particular metal, by a subtractive process, such as cutting or stamping, or wherein the spring arrangement is manufactured from wires.

12. The micro suspension device of claim 1, wherein a shape of the spring arrangement in which it has minimal potential energy is not a flat configuration.

13. The micro suspension device of claim 1, comprising an actuator arranged to exert a force acting on the carrier in a direction parallel to the reference axis, wherein this force acts on the carrier at a point that is spaced from the reference axis.

14. A spring arrangement for use in a micro suspension device, the spring arrangement being designed to be connected to a base and a carrier for moving the carrier relative to the base along a reference axis, and for suspending and guiding the carrier relative to the base, wherein: the spring arrangement comprises at least a first spring unit and a second spring unit, each spring unit comprises a first arm and a second arm, each of said first and second arms comprises a first section, a second section, and a connection node, the first section extends from a first attachment node, to the connection node, the second section extends from the connection node to a second attachment node, wherein the first attachment node and the second attachment node are adjacent to one another wherein in each spring unit, the connection node of the first arm is connected to the connection node of the second arm, the first arm and second arm are mirror-symmetric to one another, and the connection nodes are spaced from a straight line connecting the attachment nodes of the first arm with the attachment nodes of the second arm.

15. The spring arrangement of claim 14, manufactured from a single piece of a flat material, comprising two spring units in a mirror-symmetric arrangement, or comprising four spring units in an arrangement with fourfold rotational symmetry.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0077] The subject matter of the invention will be explained in more detail in the following text with reference to exemplary embodiments which are illustrated in the attached drawings, which schematically show:

[0078] FIG. 1 a spring arrangement with curved arms;

[0079] FIG. 2 a spring arrangement combined with a carrier and a base;

[0080] FIG. 3 a micro suspension device with spring arrangements with two spring units spanning half of the circumference of a carrier, in a planar position;

[0081] FIG. 4 a micro suspension device with spring arrangements with four spring units spanning the entire circumference of a carrier, in a planar position;

[0082] FIG. 5 a spring arrangement with straight arms;

[0083] FIG. 6 a spring arrangement designed to be wrapped around a carrier;

[0084] FIG. 7 a micro suspension or positioning device with spring arrangements in an extended position; and

[0085] FIG. 8 the same, but with connection nodes being free to move, in order to provide a better understanding of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[0086] In principle, identical parts are provided with the same reference symbols in the figures.

[0087] FIG. 1 shows a spring arrangement 1 with curved arms, and FIG. 2 the same but combined with a carrier and a base, the spring arrangement 1 includes two spring units 2, a first spring unit 21 and a second spring unit 22. The spring units 2 are mirror images of each other. Each of the spring units 2 includes a first arm 31 and a second arm 32. The arms 31, 32 are mirror images of each other. Each arm 31, 32 in turn includes a first section 41 which extends from a first (or base) attachment node 51 to a connection node 43, and a second section 42 which extends, in parallel to the first section 41, from the connection node 43 to a second (or carrier) attachment node 52. At the first and second attachment nodes 51, 52 the spring arrangement 1 is attached to the carrier 62 and the base 61, respectively. The elements of the spring arrangement 1 lie in a plane, also called reference plane 63, in this case the plane of the drawing. The spring arrangement 1 allows the carrier 62 to move in the direction of a reference axis 64 which is normal to the reference plane 63.

[0088] FIG. 3 shows a micro suspension device with spring arrangements 11, 12 with two spring units spanning half of the circumference of a carrier, in a planar position. FIG. 3a shows an elevated and FIG. 3b a perspective view. A lateral view is identical to that of FIG. 4c. A first (or lower) spring arrangement 11 and a second (or upper) spring arrangement 12 are shown, connected to a lower or upper part of the base 61 and carrier 62, respectively, and acting in parallel. In principle, just one spring arrangement 1 could be sufficient to support and guide the carrier 62.

[0089] The geometry of the spring arrangements 11, 12 is essentially the same as in FIGS. 1 and 2, the main difference being that the spring arrangements 11, 12 are shown in more detail, being cut or stamped from a piece of sheet material, typically metal. A base 61 and carrier 62 are shown as part of the same sheet, in reality they can be other objects constituting the base 61 and, for example, a lens barrel, to which the spring arrangement 1 is attached. The reference plane 63 is parallel to the planes that are drawn to represent the base 61. The reference axis 64 is normal to this and is designated as z-Axis. The reference axis 64 passes through the centre of the carrier 62 and typically is an axis of symmetry of the carrier 62 and/or the spring arrangement 1.

[0090] An angular position of a point on the spring arrangement 1 or a point near the circumference of the carrier 62 can be defined as an angle (theta) seen from the centre of the carrier 62, between a fixed reference vector x in the reference plane 63, and a radial vector from the centre to said point.

[0091] An actuator plane 65 shows a plane, normal to the reference plane 63 and including the reference axis 64, in which forces or a force vector from an actuator (not shown) can act between the base 61 and the carrier 62. If such a force acts near the periphery of the carrier 62 it gives rise to a torque that induces the carrier 62 to tilt. In the present example, the actuator plane 65 forms a plane of symmetry for the spring arrangement 1. With the actuator 66 force acting in this plane, on the same side of the carrier 62 at which the spring arrangement 1 is arranged, the tilting of the carrier 62 will be comparatively small, compared to other placements of the actuator 66.

[0092] FIG. 4 shows a micro suspension device with spring arrangements with four spring units 2 spanning the entire circumference of a carrier, in a planar position. FIG. 4a shows an elevated, FIG. 4b a perspective, and FIG. 4c a lateral view. Again, a first (or lower) spring arrangement 11 and second (or upper) spring arrangement 12 are shown. Each spring arrangement 11, 12 includes the same kind of spring units 2 as FIG. 3. This arrangement is well suited for a force acting symmetrically on the carrier 62, providing for good stability with regard to tilting by disturbances.

[0093] The magnified views shown in FIG. 4b illustrate a connection node 43 and attachment nodes 51, 52 linking the spring arrangement 1 to the base 61 and carrier 62. The attachment nodes 51, 52 are shown in a simplified manner, as if the spring arrangement 1 and base 61 or carrier 62 were the same part. In reality, the attachment nodes 51, 52 can include any kind of form or material or force fit, e.g., gluing, welding, a hook on a peg, etc. The magnified views pertain to the embodiment of FIG. 3 as well.

[0094] FIG. 5 shows a spring arrangement 1 with straight arms. The general properties of the spring arrangement 1 of the previous figures can be implemented here as well, the difference lying essentially in the geometry of the arms 31, 32. In particular, the spring arrangement 1 can be manufactured from a flat piece of sheet material, extending in the plane of the image.

[0095] In the embodiments shown so far, the attachment nodes 51, 52 are designed to move, when the carrier 62 moves relative to the base 61, in directions that are normal to the plane of the image in FIGS. 1, 2 and 5.

[0096] FIG. 6 shows a spring arrangement 1 designed to be wrapped around a carrier. The general properties of the spring arrangement 1 of the previous figures can be implemented here as well. In particular, the spring arrangement 1 can be manufactured from a flat piece of sheet material, extending in the plane of the image. However, in contrast to the other embodiments, the plane in which this spring arrangement 1 lies is designed to be bent around the circumference of the 62, before the attachment nodes 51, 52 are attached to the base 61 and carrier 62. The attachment nodes 51, 52 thus are designed to move, when the carrier 62 moves relative to the base 61, in directions that are parallel to the plane of the image in FIG. 6. In order for the sections 41, 42 to be able to flex easily, within the plane of the original sheet material, they can be relatively thin. In alternative embodiments, the sections 41, 42 can be made of wires.

[0097] FIG. 7 shows a micro suspension or positioning device with spring arrangements in an extended position. A first (or lower) spring arrangement 11 and second (or upper) spring arrangement 12 are shown. An actuator 66 and its approximate position at which it acts on the carrier 62 is shown symbolically. A resulting actuator force vector Fm causes the carrier 62 to be moved along the reference axis 64. A corresponding torque Mm=Fm*D, where D is the distance from the reference axis to the point at which Fm acts on the carrier 62, induces the carrier 62 to tilt.

[0098] Because the arms 31, 32 are connected at the connection nodes 43, the connection nodes 43 of all arms 31, 32 are constrained to be at the same height along the reference axis 64. The height difference hz between connection nodes 43 thus is zero. Relative movement of each pair of attachment nodes is essentially constrained to directions parallel to the reference axis. Consequently, a low value of tilt is attained per unit of movement along the reference axis.

[0099] The connection of the connection nodes 43 makes the spring arrangement 1 hyperstatic or statically indeterminate. The compliant springs are deformed by both flexion and by traction of the arms.

[0100] In both FIG. 7 and FIG. 8, displacement in the z-direction is highly exaggerated for the purpose of illustration.

[0101] FIG. 8 shows what would happen if the connection nodes were free to move, in order to provide a better understanding of the invention. The deformation of the springs is isostatic, or statically determinate. Each arm 31, 32 is free to tilt, and the connection nodes 43 are moved to different heights. For a unit of movement of the carrier 62 in the direction of the reference axis 64, the tilt is significantly larger than for the same movement in the situation in FIG. 7.

[0102] While the invention has been described in present embodiments, it is distinctly understood that the invention is not limited thereto, but may be otherwise variously embodied and practised within the scope of the claims.