Lens positioning system

Patent metadata

Field	Value
Publication number	US-10288875-B2
Application number	US-201715649342-A
Country	US
Kind code	B2
Filing date	Jul 13, 2017
Priority date	Jun 6, 2014
Publication date	May 14, 2019
Grant date	May 14, 2019

Abstract

A scanner includes a lens assembly comprising a lens having a lens axis and a positioning system to adjust a focal plane of the lens assembly. The positioning system includes an outer element, an inner element that houses the lens assembly, and a linear-motion bearing that couples the inner element to the outer element. The linear-motion bearing includes a first element coupling and a second element coupling. The linear-motion bearing provides a single degree of translational movement of the inner element along the lens axis.

First claim

What is claimed is:

1. A device comprising:
an outer element;
an inner element disposed within the outer element; and
a linear-motion bearing that couples the inner element to the outer element, the linear-motion bearing providing a single degree of translational movement of the inner element along a longitudinal axis, the linear-motion bearing comprising at least a first element coupling comprising:
a first inner element region coupled to the inner element;
a first outer element region coupled to the outer element; and
one or more first flexures that connect the first inner element region to the first outer element region of the first element coupling, wherein the one or more first flexures have a rotationally symmetric pattern, and wherein the first inner element region of the first element coupling rotates in a direction in accordance with the rotationally symmetric pattern in response to movement of the inner element along the longitudinal axis.

2. The device of claim 1 , the linear-motion bearing further comprising:
a second element coupling comprising:
a second inner element region coupled to the inner element;
a second outer element region coupled to the outer element; and
one or more second flexures that connect the second inner element region to the second outer element region of the second element coupling, wherein the one or more second flexures have the rotationally symmetric pattern, and wherein the second inner element region of the second element coupling rotates in the direction in accordance with the rotationally symmetric pattern in response to the movement of the inner element along the longitudinal axis.

3. The device of claim 2 , wherein the first element coupling is coupled to a first end of the inner element and a first end of the outer element along the longitudinal axis and the second element coupling is coupled to a second end of the inner element and a second end of the outer element along the longitudinal axis.

4. The device of claim 1 , wherein:
the inner element further comprises a permanent magnet;
the outer element comprises an electromagnet; and
the device further comprises a controller to induce a current through the electromagnet to move the inner element with respect to the outer element along the longitudinal axis.

5. The device of claim 4 , wherein:
the permanent magnet comprises a first pole and a second pole that define a magnetic axis parallel to the longitudinal axis; and
the electromagnet comprises a first coil wound in a first direction around the first pole and a second coil wound in a second direction around the second pole.

6. The device of claim 4 , further comprising:
a linear encoder to measure a current position of the inner element with respect to the outer element; and
the controller is further to:
receive command data indicative of a desired position of the inner element with respect to the outer element; and
induce the current through the electromagnet based at least in part on the command data.

7. The device of claim 1 , wherein the device is a scanner, wherein the inner element comprises a lens assembly comprising a lens having the longitudinal axis, and wherein movement of the inner element with respect to the outer element along the longitudinal axis adjusts a focal plane of the lens assembly.

8. The device of claim 7 , wherein the scanner is an intraoral scanner.

9. The device of claim 7 , wherein the lens assembly comprises confocal optics.

10. The device of claim 1 , wherein each flexure of the one or more first flexures comprises a curved strip of material that is generally orthogonal to the longitudinal axis and to a radial axis perpendicular to the longitudinal axis.

11. The device of claim 1 , wherein the one or more first flexures comprises at least three flexures.

12. The device of claim 11 , wherein each flexure of the at least three flexures connects to the first inner element region at a respective first point and connects to the first outer element region at a respective second point, wherein a first distance of the first point from the longitudinal axis is less than a second distance of the second point from the longitudinal axis, and wherein the first point is rotationally offset from the second point.

13. The device of claim 1 , wherein the inner element and the outer element are approximately concentric.

14. The device of claim 1 , wherein the first element coupling comprises a leaf spring and each of the one or more flexures comprises a leaf spring element.

15. The device of claim 1 , wherein the one or more first flexures have a length, and wherein a travel distance of the linear-motion bearing is approximately 10% of the length.

16. The device of claim 15 , wherein the length is about 20-40 mm.

17. The device of claim 1 , wherein the rotationally symmetric pattern provides resistance to motion caused by thermal drift.

18. An intraoral scanner comprising:
a lens assembly comprising a lens having a lens axis; and
a positioning system to adjust a focal plane of the lens assembly, the positioning system comprising:
an outer element;
an inner element disposed within the outer element, wherein the lens assembly is housed in the inner element; and
a linear-motion bearing that couples the inner element to the outer element, the linear-motion bearing providing a single degree of translational movement of the inner element along the lens axis, the linear-motion bearing comprising:
a first element coupling comprising a first inner element region coupled to the inner element, a first outer element region coupled to the outer element, and first flexures that connect the first inner element region to the first outer element region of the first element coupling, wherein the first flexures have a rotationally symmetric pattern about the lens axis, wherein each flexure of the first flexures comprises a curved strip of material that is generally orthogonal to the lens axis and to a radial axis perpendicular to the lens axis, and wherein the first inner element region of the first element coupling rotates in a direction in accordance with the rotationally symmetric pattern as the inner element is moved along the lens axis; and
a second element coupling comprising a second inner element region coupled to the inner element, a second outer element region coupled to the outer element, and second flexures that connect the second inner element region to the second outer element region of the second element coupling, wherein the second flexures have the rotationally symmetric pattern about the lens axis, wherein each flexure of the second flexures comprises a curved strip of material that is generally orthogonal to the lens axis and to the radial axis, wherein the second inner element region of the second element coupling rotates in the direction in accordance with the rotationally symmetric pattern as the inner element is moved along the lens axis, and wherein the first inner element region and the second inner element region rotate together in the direction to rotate the inner element and prevent translational movement of the lens assembly normal to the lens axis.

19. The intraoral scanner of claim 18 , wherein the lens assembly comprises confocal optics.

20. A method comprising:
receiving, by a controller, command data indicative of a desired position of an inner element of a positioning system with respect to an outer element of the positioning system, wherein the positioning system comprises the outer element, the inner eleme

Assignees

• Align Technology Inc

Inventors

• Boltanski Rami

Classifications

• A61C9/0053

  Optical means or methods, e.g. scanning the teeth by a laser or light beam · CPC title

• A61B1/00172 Primary

  with means for scanning · CPC title

• G02B7/08

  adapted to co-operate with a remote control mechanism · CPC title

• H02K41/0356

  moving along a straight path · CPC title

• A61C9/0066

  Depth determination through adaptive focusing · CPC title