Rotational actuator for optical device and camera module having the same

Patent metadata

Field	Value
Publication number	US-9857549-B1
Application number	US-201615386300-A
Country	US
Kind code	B1
Filing date	Dec 21, 2016
Priority date	Jul 1, 2016
Publication date	Jan 2, 2018
Grant date	Jan 2, 2018

Abstract

Disclosed is a rotational actuator for an optical device, which includes a rotary shaft capable of freely rotating at a fixed position; a first shape-memory alloy wire fixed in a first direction to give a rotation moment to the rotary shaft, the first shape-memory alloy wire making length contraction with respect to the rotary shaft when an electric current is applied thereto; a second shape-memory alloy wire fixed in a second direction opposite to the first direction to give a rotation moment with respect to the rotary shaft, the second shape-memory alloy wire making length contraction with respect to the rotary shaft when an electric current is applied thereto; and a control unit configured to supply an electric current to the first shape-memory alloy wire when rotating the rotary shaft in the first direction and supply an electric current to the second shape-memory alloy wire when rotating the rotary shaft in the second direction.

First claim

What is claimed is:

1. A rotational actuator for an optical device, comprising:
a rotary shaft capable of freely rotating at a fixed position;
a first shape-memory alloy wire fixed in a first direction to give a rotation moment to the rotary shaft, the first shape-memory alloy wire making length contraction with respect to the rotary shaft when an electric current is applied thereto;
a second shape-memory alloy wire fixed in a second direction opposite to the first direction to give a rotation moment with respect to the rotary shaft, the second shape-memory alloy wire making length contraction with respect to the rotary shaft when an electric current is applied thereto; and
a control unit configured to supply an electric current to the first shape-memory alloy wire when rotating the rotary shaft in the first direction and supply an electric current to the second shape-memory alloy wire when rotating the rotary shaft in the second direction.

2. The rotational actuator for an optical device according to claim 1 , wherein the control unit blocks power supply to the first shape-memory alloy wire or the second shape-memory alloy wire when the rotary shaft completely rotates in first direction or second direction.

3. The rotational actuator for an optical device according to claim 1 , wherein the first shape-memory alloy wire and the second shape-memory alloy wire are respectively made of a single shape-memory alloy wire and adhered to the rotary shaft at a boundary point of the first direction and the second direction; and
the rotary shaft is electrically connected to the single shape-memory alloy wire as a common negative electrode terminal, and first and second independent positive electrode terminals are respectively electrically connected to both ends of the single shape-memory alloy wire.

4. The rotational actuator for an optical device according to claim 1 , wherein the first shape-memory alloy wire and the second shape-memory alloy wire are respectively made of a single shape-memory alloy wire and wound on the rotary shaft by at least one turn; and
the rotary shaft is electrically connected to the single shape-memory alloy wire as a common negative electrode terminal, and first and second independent positive electrode terminals are respectively electrically connected to both ends of the single shape-memory alloy wire.

5. The rotational actuator for an optical device according to claim 1 , wherein middle portions of the first shape-memory alloy wire and the second shape-memory alloy wire are coupled to the rotary shaft to be capable of expanding or contracting so that both ends of each shape-memory alloy wire extend in the first direction and the second direction, respectively; and
both ends of each shape-memory alloy wire are electrically connected to a negative electrode terminal and first and second independent positive electrode terminals.

6. The rotational actuator for an optical device according to claim 5 , wherein the negative electrode terminal to which one of both ends of each shape-memory alloy wire is connected is a single common negative electrode terminal.

7. The rotational actuator for an optical device according to claim 1 , further comprising a rotator fixed to the rotary shaft.

8. The rotational actuator for an optical device according to claim 7 , wherein two filters having different characteristics as an optical window are provided at the rotator.

9. The rotational actuator for an optical device according to claim 8 , wherein the two filters are respectively an infrared cutoff filter and an infrared pass filter.

10. A camera module, at which the rotational actuator for an optical device defined in claim 1 is loaded.

11. The camera module according to claim 10 , wherein the rotational actuator for an optical device is loaded on a surface of the camera module at which an opening is formed to allow light to pass to a lens assembly of the camera module.

12. The camera module according to claim 11 , wherein the rotary shaft is installed at an edge of the camera module.

13. The camera module according to claim 12 , wherein the first direction and the second direction extend from the rotary shaft with an angle of 90°.

14. The camera module according to claim 13 , wherein the surface at which the opening is formed has a rectangular shape, and the first shape-memory alloy wire and the second shape-memory alloy wire respectively extend along two edges of the rectangular surface.

15. The camera module according to claim 10 , wherein the camera module having an infrared cutoff filter and an infrared pass filter at the rotator is used for iris recognition.

Assignees

• Jahwa Electronics Co Ltd

Inventors

• Shin Doo Sik
• Kim Sang Chul

Classifications

• H04N23/55

  Optical parts specially adapted for electronic image sensors; Mounting thereof · CPC title

• H04N23/54

  Mounting of pick-up tubes, electronic image sensors, deviation or focusing coils · CPC title

• G06V10/143

  Sensing or illuminating at different wavelengths · CPC title

• H04N5/33

  Transforming infrared radiation (cameras or camera modules for generating image signals from infrared radiation H04N23/20; circuitry of SSIS for transforming infrared radiation into image signals H04N25/20) · CPC title

• G02B7/006 Primary

  Filter holders · CPC title