Rotational actuator for optical device and camera module having the same

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.

Description

CROSS-REFERENCE TO RELATED APPLICATION AND CLAIM OF PRIORITY[0001]The present application claims priority to Korean Patent Application No. 10-2016-0083741 filed on Jul. 1, 2016 in the Korea Intellectual Property Office, the disclosures of which are incorporated herein by reference.BACKGROUND1. Technical Field[0002]The present disclosure relates to a rotational actuator for an optical device and a camera module having the same, and more particularly, to a rotational actuator for an optical device, which is integrally provided at a camera module mounted to a portable terminal but is capable of rotating without giving any serious influence on size and power consumption of the camera module, and a camera module having the same.2. Background Art[0003]Generally, a camera module for taking an image is basically loaded on a portable terminal (hereinafter, referred to as a “portable terminal”) such as a cellular phone, a smart phone, a PDA or the like.[0004]The camera module loaded on the po...

AI Technical Summary

Benefits of technology

[0016]The present disclosure is directed to providing a rotational actuator for an optical device, which is integrally provided at a camera module mounted to a portable terminal and may give a rotation with a new structure without giving an influence on the size and power consumption of the camera module.

[0031]The rotational actuator for an optical device according to the present disclosure configured as above may rotate a rotary shaft in both directions just with a simple structure for adhering a thin shape-memory alloy wire to the rotary shaft and selectively supplying an electric current. Therefore, the rotational actuator may be very easily applied to a camera module included in a small portable terminal in an integrated form.

[0032]In addition, since the wire is prepared simply without processing a shape-memory alloy into a special shape and is just used to make length contraction by a resistance heat, it is possible to ensure very reliable operation.

[0033]Moreover, since the shape-memory alloy wire has a diameter of just several ten micrometers, a sufficient resistance heat may be generated just with a fine electric current. Therefore, the rotational actuator has low power consumption and thus is very suitable for a portable terminal which is sensitive to power control.

Problems solved by technology

The camera module loaded on the portable terminal should have a very small design, and thus at early stages, the camera module has a deteriorated photographing function in comparison to general digital cameras.

Meanwhile, recently, security of personal information stored in the portable terminal has become a serious social issue.

However, the near-infrared ray or infrared ray causes crosstalk to the imaging device to weaken color reproduction of the imaging device and deteriorate a signal-to-noise ratio of the imaging device.

In other words, since the filter unit is not integrated with the camera module, the number of parts and assembling processes increases, and thus a communication terminal manufacturer cannot easily select the filter unit.

Thus, it is substantially impossible to ensure a space for mounting a separate filter unit.

However, if a VCM actuator or piezo-electric actuator broadly used in the art is applied to the existing camera module, the camera module has too large size to be applied to the portable terminal.

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