Lens positioning system

Patent metadata

Field	Value
Publication number	US-9709803-B2
Application number	US-201615211377-A
Country	US
Kind code	B2
Filing date	Jul 15, 2016
Priority date	Jun 6, 2014
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

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 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 one or more first flexures that connect the first inner element region to the first outer element region of the first element coupling; 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 one or more second flexures that connect the second inner element region to the second outer element region of the second element coupling.

2. The scanner of claim 1 , wherein the scanner is an intraoral scanner.

3. The scanner of claim 1 , wherein the first flexures have a rotationally symmetric pattern about the lens axis and the second flexures have the rotationally symmetric pattern about the lens axis.

4. The scanner of claim 3 , wherein the first element coupling and the second element coupling each rotates in a same 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 second inner element region rotate together in the same direction to rotate the inner element and prevent translational movement of the lens assembly normal to the lens axis.

5. The scanner of claim 3 , wherein rotationally symmetric pattern about the lens axis provides resistance to motion caused by thermal drift.

6. The scanner of claim 1 , 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 lens 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 lens axis.

7. The scanner of claim 1 , wherein the one or more first flexures and the one or more second flexures bend as the inner element is moved along the lens axis with respect to the outer element.

8. The scanner of claim 1 , wherein the one or more first flexures comprises at least three flexures, the one or more second flexures comprises at least three flexures, the first element coupling comprises a homogenous material and the second element coupling comprises the homogenous material.

9. The scanner of claim 1 , wherein the inner element, the outer element and the lens assembly are all approximately concentric.

10. The scanner of claim 1 , wherein the first element coupling comprises a first leaf spring and the second element coupling comprises a second leaf spring.

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

12. The scanner of claim 11 , wherein the length is about 20-40 mm.

13. The scanner of claim 1 , wherein the positioning system is capable of changing the focal plane of the lens assembly at a speed of approximately 60 mm per second.

14. The scanner of claim 1 , wherein:
the inner element comprises a permanent magnet with a first pole and a second pole that define a magnetic axis parallel to the lens axis;
the outer element 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; and
the scanner further comprises a controller to induce a current through the first coil and the second coil to move the inner element with respect to the outer element along the lens axis.

15. The scanner of claim 14 , further comprising:
a linear encoder to measure a current position of the inner element with respect to the outer element;
wherein the controller is further to:
receive command data indicative of a desired position of the inner element with respect to the outer element;
receive position data from the linear encoder indicative of the current position of the inner element with respect to the outer element; and
induce the current through the first coil and the second coil based on the command data and the position data.

16. A method comprising:
receiving, by a controller of a scanner, position data indicative of a current 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 element disposed within the outer element, a linear-motion bearing that couples the inner element to the outer element, and a lens assembly housed in the inner element, the lens assembly comprising a lens having a lens axis;
receiving, by the controller, command data indicative of a desired position of the inner element with respect to the outer element;
determining, by the controller, a strength of a current to be applied to one or more electromagnets based on the command data and the position data; and
inducing, by the controller, a current having the strength in the one or more electromagnets to move the inner element with respect to the outer element along the lens axis and change a focal plane of the lens assembly, wherein the linear-motion bearing is to rotate the inner element in a clockwise or counterclockwise direction around the lens axis and prevent translational movement of the lens assembly normal to the lens axis as the inner element is moved with respect to the outer element along the lens axis.

17. The method of claim 16 , further comprising:
changing the focal plane of the lens assembly at a speed of up to approximately 60 mm per second.

18. A positioning system for a scanner comprising:
an outer element;
an inner element disposed within the outer element;
a lens assembly housed in the inner element, the lens assembly comprising a lens having a lens axis; 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, wherein the linear-motion bearing is to rotate the inner element in a clockwise or counterclockwise direction around the lens axis and prevent translational movement of the lens assembly normal to the lens axis as the inner element is moved with respect to the outer element along the lens axis.

19. The positioning system for a scanner of claim 18 , wherein the linear-motion bearing comprises:
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; 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 one or more second flexures that connect the second inner element region to the second outer element region of the second element coupling.

Assignees

• Align Technology Inc

Inventors

• Boltanski Rami

Classifications

• A61B1/002

  having rod-lens arrangements (A61B1/055 takes precedence) · CPC title

• A61B1/24

  for the mouth, i.e. stomatoscopes, e.g. with tongue depressors; Instruments for opening or keeping open the mouth · CPC title

• A61B1/00188

  with focusing or zooming features · CPC title

• G02B7/023 Primary

  permitting adjustment · CPC title

• H02K41/0356

  moving along a straight path · CPC title