US-12619052-B2 - Actuator for reflector having moving frame with reflector and camera module including the same

US12619052B2US 12619052 B2US12619052 B2US 12619052B2US-12619052-B2

Abstract

An actuator for a reflector according to an embodiment of the present disclosure includes a moving frame having a reflector configured to reflect light to a lens, and a magnet, a base frame configured to provide a moving space for the moving frame, a driving coil configured to generate a magnetic force at the magnet so that the moving frame rotates based on the base frame, a guide rail formed at any one of the moving frame and base frame and having a rounded shape, a holder provided to any one of the moving frame and the base frame not provided with the guide rail, provided in a direction facing the guide rail, and having a groove shape; and a ball arranged between the guide rail and the holder.

Inventors

Chul Soon Park
In Su Kang
Hyeon ik CHO
Jae Seon Lee
Je Seung YEON

Assignees

JAHWA ELECTRONICS CO., LTD.

Dates

Publication Date: 20260505
Application Date: 20210408
Priority Date: 20200409

Claims (7)

1 . An actuator for a reflector, comprising: a moving frame having a reflector configured to reflect light to a lens, and a magnet; a base frame configured to provide a moving space for the moving frame; a driving coil configured to generate a magnetic force at the magnet so that the moving frame rotates based on the base frame; a guide rail formed at any one of the moving frame and the base frame and having a rounded shape; a holder provided to any one of the moving frame and the base frame not provided with the guide rail, provided in a direction facing the guide rail, and having a groove shape; and a ball arranged between the guide rail and the holder, and wherein the moving frame rotates along a path corresponding to the guide rail.
2 . The actuator for a reflector according to claim 1 , wherein the holder includes a plurality of holders arranged side by side to correspond to a longitudinal direction of the guide rail, and wherein the ball is arranged at each of the plurality of holders.
3 . The actuator for a reflector according to claim 2 , wherein the plurality of holders are spaced apart from the guide rail by the same distance based on the direction facing the guide rail.
4 . The actuator for a reflector according to claim 1 , wherein an inner surface of the holder includes at least one plane that makes a point contact with the ball.
5 . The actuator for a reflector according to claim 4 , wherein the plane has a shape that becomes narrower inward.
6 . The actuator for a reflector according to claim 1 , further comprising: a yoke provided to the base frame to generate an attractive force at the magnet, wherein a center of a portion of the yoke facing the magnet coincides with a center of the magnet.
7 . A camera module, comprising the actuator for a reflector according to claim 1 .

Description

CROSS REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY This application claims benefit under 35 U.S.C. 119, 120, 121, or 365(c), and is a National Stage entry from International Application No. PCT/KR2021/004414, filed Apr. 8, 2021, which claims priority to the benefit of Korean Patent Application No. 10-2020-0043291 filed in the Korean Intellectual Property Office on Apr. 9, 2020, the entire contents of which are incorporated herein by reference. BACKGROUND 1. Technical Field The present disclosure relates to an actuator for a reflector and a camera module including the same, and more specifically, to an actuator for a reflector that implements OIS or the like through improvement of a guiding structure that physically supports a ball. 2. Background Art As the hardware technology for image processing has been developed and the user needs for image shooting have increased, functions such as autofocus (AF) and optical image stabilization (OIS) have been applied to a camera module or the like, mounted to a portable terminal such as a cellular phone and a smart phone as well as an independent camera device. An autofocus (AF) function (or, an automatically focusing function) means a function of a focal length to a subject by linearly moving a carrier having a lens in an optical axis direction to generate a clear image at an image sensor (CMOS, CCD, etc.) located at the rear of the lens. In addition, an optical image stabilization (OIS) function means a function of improving the sharpness of an image by adaptively moving the carrier having a lens in a direction to compensate for the shaking when the lens is shaken due to trembling. One typical method for implementing the AF or OIS function is to install a magnet (a coil) on a mover (a carrier) and install a coil (a magnet) on a stator (a housing, or another type of carrier, or the like), and then generate an electromagnetic force between the coil and the magnet so that the mover moves in the optical axis direction or in a direction perpendicular to the optical axis. Recently, a mobile terminal is equipped with a zoom lens that has specifications for variably adjusting a focal length or capture an image from a distance in order to meet the increased user needs and implement user convenience in a more diverse manner. The zoom lens has a structure in which a plurality of lenses or lens groups are arranged side by side, or has a characteristic that the lens is long based on the optical axis, so a larger mounting space must be provided in the mobile terminal. Recently, in order to organically graft the physical characteristics of the zoom lens with the geometric characteristics of a portable terminal, an actuator or camera module having a physical structure that allows the light of a subject to be refracted using a reflector placed in front of the lens has been disclosed. The actuator or the like employing a reflector does not correctively move the lens according to hank shaking, but implements OIS for the hand shaking by moving the reflector, which reflects the light of the subject, toward the lens in one or two axes. Typically, a guide rail is formed on each of a moving body (an object provided with a reflector) and a fixed body, and a plurality of balls are disposed therebetween so that the moving body rotates along the guide rail while being supported by the balls. However, in this conventional structure, since the balls arranged between the guide rails move freely, the positions of the balls are not fixed or specified, so the physical points supported by the balls are constantly changing. If the physical points supported by the balls are changed in this way, the distance between the balls changes, and also the balls tend to be biased in one direction repeatedly. In addition, the biased direction or position also changes every moment, so the balance support of the moving body on which the reflector is mounted is broken, thereby causing the reflector to be tilted. In particular, in the case of a high magnification lens such as a zoom lens, even if a slight tilt occurs, it has a significant effect on the image sensor, so that a significant amount of image deterioration may occur. In addition, there is a technique in which three or more balls are arranged between the guide rails to reduce the tilting problem of the moving body. However, even in this case, since the balls are constantly moving, it is difficult to fundamentally solve the tilting problem. Furthermore, in this technique, balls of relatively small size must be arranged. However, as the size of the balls decreases, the physical behavior characteristics of the balls due to rolling/rotating and moving deteriorate, which may adversely affect the precision of OIS. In addition, as the size of the balls is smaller, the balls made of a material such as metal or ceramic material having higher rigidity than plastic apply a greater physical pressure or impact to the guide rails made of plastic or the like, so