KR101661325B1 - Zoom lens system and photographic device capable of image stabilizing - Google Patents

Abstract

A zoom lens system and an image pickup apparatus are disclosed. The disclosed zoom lens system includes a first zoom lens, a second zoom lens, And an optical path switching member which is disposed in an optical path between the first zoom lens and the second zoom lens and is driven to rotate by changing the optical axis so that light from the first zoom lens is incident on the second zoom lens.

Description

Technical Field [0001] The present invention relates to a zoom lens system having an image stabilization function,

The disclosed zoom lens system and image pickup device are related to a zoom lens system having an image stabilization function and an image pickup device employing the zoom lens system.

The technology of digital camera has been developed remarkably due to the development of CCD (Charge Coupled Device) and CMOS (Complementary Metal-Oxide Semiconductor) which are semiconductor image acquisition devices.

2. Description of the Related Art In recent years, image-forming optical instruments such as digital cameras have been increasingly emphasized on portability, and accordingly, they have been required to be smaller and lighter in weight. This is because the amount of camera shake that varies depending on the variable focal length of the lens must be corrected more precisely in realizing the high magnification zoom.

Optical Image Stabilizer (OIS), Electrical Image Stabilizer (EIS) and Digital Image Stabilizer (DIS) are among the ways to compensate for camera shake.

 As an example of the optical correction method, a lens shift method in which a correction lens group is incorporated is used. In this case, the number of lenses increases, the lens barrel must be large, and the performance of the optical system may be deteriorated.

Embodiments of the present invention provide a zoom lens system and an image pickup apparatus having a camera shake correction function according to the needs described above.

A zoom lens system according to an embodiment of the present invention includes a first zoom lens; A second zoom lens; And a light path switching member disposed at an optical path between the first zoom lens and the second zoom lens and rotated by being rotated by changing an optical axis so that light from the first zoom lens is incident on the second zoom lens.

The light path switching member includes an incident surface on which light is incident, a total reflection surface that changes the path by totally reflecting the incident light, and an exit surface through which light is emitted.

The light path switching member may be composed of a prism.

The light path changing member may be formed of a lens surface on which the incident surface and / or the emitting surface have a refracting power.

The image pickup device according to the embodiment of the present invention includes a first zoom lens, a second zoom lens, and a second zoom lens disposed in an optical path between the first zoom lens and the second zoom lens, so that light from the first zoom lens is incident on the second zoom lens. A zoom lens system having a light path switching member for changing an optical path changing member; An image generating unit for generating an image of a subject from light incident through the zoom lens system; A camera-shake correction actuator for correcting camera-shake by rotationally driving the optical path changing member; An image shake detecting unit for detecting a shaking motion; A zoom position sensing unit for sensing a zoom position of the zoom lens system; And a processor for driving the driving unit according to information from the shaking motion sensing unit and the zoom position sensing unit.

The camera-shake correction actuator may be any one of a voice coil motor, an ultrasonic motor, and a piezoelectric motor.

The shaking motion sensing unit may be a gyro sensor or an angular velocity sensor.

The zoom position sensing unit may include an MR sensor or a Hall sensor.

Wherein the optical path changing member includes an incident surface on which light is incident, a total reflection surface that changes the path by totally reflecting the incident light, and an exit surface through which light is emitted.

The light path changing member may be a prism, and the incident surface and / or the emitting surface may be formed of a lens surface having a refractive power.

The zoom lens system according to the embodiment of the present invention realizes a high magnification through a two-stage configuration with a light path switching member interposed therebetween, and rotationally drives the light path switching member to precisely compensate for camera shake. In addition, it is possible to perform high-speed driving with the correction of the shaking motion by the rotational movement method, and is suitable for a high magnification. Further, the thickness of the lens barrel is not increased as compared with the camera shake correction of the lens movement type, and no separate correction lens can be used, so that the optical performance is not deteriorated.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals denote the same elements, and the sizes of the respective elements in the drawings may be exaggerated for clarity and convenience.

 1 is a diagram showing an optical arrangement of a zoom lens system 100 according to an embodiment of the present invention. The zoom lens system 100 includes a first zoom lens 110, a second zoom lens 130 and a first zoom lens 110 disposed in the optical path between the first zoom lens 110 and the second zoom lens 130, And an optical path changing member 120 rotatably driven to change the optical axis so that light from the first zoom lens 110 is incident on the second zoom lens 130.

For example, when the magnification of the first zoom lens 110 is m, the magnification of the second zoom lens 130 is m, and the magnification of the second zoom lens 130 is m, the first zoom lens 110 and the second zoom lens 130 form a two- The total magnification is m x n. This structure is adopted to realize a high magnification with a compact appearance. The first zoom lens 110 and the second zoom lens 130 each have a plurality of lens groups, and at least some lens groups of the plurality of lens groups move in a predetermined rule along the optical axis to change a focal distance. And the lens structure shown is an exemplary one.

The optical path changing member 120 includes an incident surface 120a on which light is incident, a total reflection surface 120c that changes the optical path by totally reflecting the incident light, and an exit surface 120b on which light is emitted, Thereby correcting the shaking motion. The light path switching member 120 is rotationally driven in the directions of the arrows A1 and A2 as shown in FIG. The camera-shake direction component includes a vertical direction pitch direction component and a horizontal direction yaw direction component, which are represented by Z direction components and X direction components, respectively. The optical path changing member 120 is rotationally driven along the direction A2 in order to correct the phase fluctuation in the image plane I due to the camera shake in the Z direction. Further, the optical path changing member 120 is rotationally driven along the direction A1 to correct the phase fluctuation in the image plane I due to the camera-shake in the X direction.

2 is a conceptual diagram for explaining the amount of shaking generation. The amount of the shaking motion is closely related to the focal length f of the lens L. [ The optical axis rotation angle? Is a value obtained by multiplying the angular acceleration? By the shutter time t, and the amount of camera shake generation? In the image plane I is calculated as follows.

χ = f · tan θ = f · tan ωt

That is, the amount of the shaking motion on the image plane due to the same rotation angle is increased in proportion to the focal length.

The zoom lens system 100 of the two-stage zoom configuration according to the embodiment of the present invention realizes a high magnification of about 20 times or more, and the focal length at the telephoto end is long, so that the image shake due to hand shake is very large. In addition, although the optical system is configured to have a "a" -shaped shape to minimize the total lens volume, it is basically bulky as compared with a structure that realizes a relatively low magnification with a one-stage zoom configuration. In such a structure, the driving system incorporating the correction lens has a limitation in correcting the shaking motion. Accordingly, in the embodiment of the present invention, the optical path changing member 120 is rotationally driven.

3 is a conceptual diagram for explaining a method for correcting hand shake in the zoom lens system 100 of the embodiment of the present invention. Hand shake in the X direction is illustrated, and the direction of the arrow A1 will be described in detail. The camera shake moves the optical axis of the entire optical system including the optical path changing member 120 so that the image shake occurs on the image plane I. [ For example, an image shake as much as -Δ occurs on the image plane I due to hand movement in the + X direction. In order to correct this, the optical path changing member 120 is rotated in the Q direction. Further, when an image shake as much as +? Occurs on the image surface I due to hand movement in the -X direction, the optical path changing member 120 is rotated in the P direction so as to correct it.

Although the X-direction camera-shake is described here as an example, the same principle applies to the case of the camera-shake in the Z-direction. It is possible to correct the image blur due to the camera-shake in the Z direction by rotating the optical path changing member 120 in either direction of the arrow A2 shown in Fig. 1, that is, in a direction capable of canceling the camera-shake.

The optical path changing member 120 has a total reflection surface 120c for changing the optical axis while the incident surface 120a and the emission surface 120b are formed in a flat prism shape. However, in the optical path changing member 120, As shown in FIG.

4A-4F illustrate various embodiments 121-126 of a light path switching member that may be employed in the zoom lens system 100 according to an embodiment of the present invention.

 The light path changing member 121 in Fig. 4A is constituted by a lens surface on which the exit surface 120b has a refracting power. For example, it may be configured as a convex surface having a positive refractive power as shown in the figure. The optical path changing member 122 shown in Fig. 4B has a convex surface with both the incident surface 120a and the exit surface 120b having a positive refracting power. The light path changing member 123 of Fig. 4C has a light exit surface 120b formed of a concave surface having a negative refracting power. In addition to the above-described configuration, it is also possible that the incident surface 120a and the emission surface 120b are all concave, or one is concave and the other convex.

The light path changing member 124 in Fig. 4D has a configuration in which the exit surface 120b is a concave surface having a negative refracting power, specifically, a lens having a concave surface in a prism having a total reflection surface 120c . The optical path changing member 125 in FIG. 4E is constituted by a concave surface having a negative refracting power on both the incident surface 120a and the emitting surface 120b. For example, the other two surfaces of the prism having the total reflection surface 120c And a lens having a concave surface on the surface thereof. The light path switching member 126 of FIG. 4F is configured such that the incident surface 120a is formed of a convex surface having positive refracting power and the emergent surface 120b is formed of a concave surface having negative refracting power. Specifically, A lens having a concave surface and a lens having a convex surface are bonded to the other two surfaces of the prism having the convex surface 120c. In addition, although not shown, a configuration in which a lens having a convex surface is bonded to the other two surfaces of the prism having the total reflection surface 120c is also possible.

The optical path changing members 121 to 126 may be subjected to an optical coating treatment such as anti-reflection (AR) coating, if necessary.

When the incident surface 120a and / or the exit surface 120b of the light path changing members 121 to 126 are formed of lens surfaces, the first zoom lens 110 and / or the second zoom lens 130, It is possible to reduce the number of lenses constituting the zoom lens system, which is more suitable for miniaturization.

5 is a schematic configuration diagram of an imaging device 200 according to an embodiment of the present invention. Referring to the drawings, there is shown a zoom lens system 100 in which light from a subject O is incident, an image generation unit 210 that generates an image of a subject from light incident through the zoom lens system 100, And a processor 250 that drives the camera shake correction unit 220, the shake sensor 240, the zoom position sensing unit 230, and the shake correction actuator 220.

The zoom lens system 100 includes a first zoom lens 110, a second zoom lens 130 and a first zoom lens 110. The zoom lens system 100 is disposed in the optical path between the first zoom lens 110 and the second zoom lens 130, And an optical path changing member 120 for changing the optical axis so as to be incident on the second zoom lens 130. Although the detailed configuration of the first zoom lens 110 and the second zoom lens 130 is not shown in the description of FIG. 1, such a two-stage zoom configuration is intended to realize a high magnification with a more compact structure, A conventional zoom lens configuration having a plurality of lens groups and at least some lens groups moving along the optical axis and varying the focal length can be employed.

The optical path changing member 120 is rotationally driven by the shake correcting actuator 220, and specifically, is configured to be rotated in two axial directions along the hand shake direction. In other words, it is rotated in the corresponding direction so as to compensate the phase fluctuation in the image plane I due to hand shake in the X and Z directions. The light path switching member 120 is shown in a prism shape having no refracting power. However, the light path switching member 120 may be formed in various shapes having refractive power, for example, the light path switching members 121 to 126 described in FIGS. Lt; / RTI >

The image generating unit 210 generates an image of the subject O from the light incident through the zoom lens system 100. For example, a CCD device or a CMOS device may be employed as the image generating unit 210. [

The camera shake correction actuator 220 rotates the optical path changing member 120 to correct an image blur due to camera shake. The camera shake correction actuator 220 rotates the optical path changing member 120 by a predetermined angle in a predetermined rotation direction in accordance with a signal from the processor 250 so that the shaking motion is canceled. As the shake correction actuator 220, for example, a voice coil motor (VCM), an ultrasonic motor, a piezoelectric motor, or the like may be employed. However, the present invention is not limited thereto, and various driving means capable of rotationally driving the light path switching member 120 can be used.

The shaking motion detector 240 detects shaking motion and inputs the shaking motion to the processor 250. More specifically, the shaking motion detector 240 may include a sensor for detecting shaking motion, a filter, an analog-digital converter (ADC), an amplifier, and the like. As the sensor for detecting camera shake, various sensors capable of detecting angular velocity caused by camera shake can be used. For example, a gyro sensor or an angular velocity sensor can be employed. The signal detected by the sensor passes through the filter, for example, is removed from the noise component, is input to the ADC, is converted into a digital signal, amplified by the amplifier, and input to the processor 250.

The zoom position detection unit 230 is for detecting the zoom position of the zoom lens system 100. The zoom lens system 100 varies in various focal lengths according to a user's selection. Even if the same angular speed is generated due to camera shake, the amount of shaking varies depending on the focal length. Accordingly, the zoom position detection unit 230 detects the zoom position of the zoom lens system 100 and inputs the detected value to the processor 250 so that the camera-shake correction amount can be calculated in consideration of the zoom position. The zoom position detection unit 240 may be a position detection sensor, for example, an MR sensor or a Hall sensor.

The processor 250 rotationally drives the optical path changing member 120 according to information from the shaking motion detector 240 and the zoom position detector 230. [ That is, the necessary correction amount, for example, the rotation direction and the rotation angle of the optical path switching member 120 are calculated in consideration of the angular acceleration inputted from the shaking motion detecting unit 240 and the focal distance inputted from the zoom position detecting unit 230, And drives the shake correction actuator 220 according to the result.

According to such a configuration and operation, the image capturing apparatus 200 of the embodiment of the present invention realizes a high performance with a high magnification and can correct the hand shake.

While the present invention has been described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. I will understand. Accordingly, the true scope of the present invention should be determined by the appended claims.

1 is a view showing an optical arrangement of a two-stage zoom lens system according to an embodiment of the present invention.

2 is a conceptual diagram for explaining the amount of shaking generation.

3 is a conceptual diagram for explaining a method of correcting the shaking motion in the two-stage zoom lens system according to the embodiment of the present invention.

4A to 4F show various embodiments of a light path switching member that can be employed in a two-stage zoom lens system according to an embodiment of the present invention.

5 is a schematic configuration diagram of an image pickup apparatus according to an embodiment of the present invention.

Description of the Related Art

100 ... zoom lens system 110 ... first zoom lens

120 to 126 ... light path switching member 130 ... second zoom lens

200 ... image pickup device 210 ... image generating section

220 ... camera shake correction actuator 230 ... zoom position detection unit

240 ... camera shake detection unit 250 ... processor

Claims (13)

Wherein at least a part of the plurality of lens groups moves along the first optical axis to change a focal distance by changing a distance between the plurality of lens groups, A first zoom lens that implements a magnification m; And a plurality of lens groups arranged along a second optical axis different from the first optical axis, wherein at least a part of the plurality of lens groups moves along the second optical axis and a distance between the plurality of lens groups is changed, A second zoom lens for changing a zoom magnification n and implementing a predetermined zoom magnification n; A second zoom lens disposed in an optical path between the first zoom lens and the second zoom lens and changing the first optical axis to the second optical axis so that light from the first zoom lens enters the second zoom lens, And a light path switching member, wherein the zoom lens system implements a magnification of mxn. The method according to claim 1, Wherein the optical path changing member includes an incident surface on which light is incident, a total reflection surface that changes the path by totally reflecting the incident light, and an exit surface on which light is emitted. 3. The method of claim 2, Wherein the optical path changing member comprises a prism. 3. The method of claim 2, Wherein the optical path changing member is formed of a lens surface having an incidence surface with a refractive power. The method according to claim 2 or 4, Wherein the light path changing member is formed of a lens surface having the light exit surface. A zoom lens system according to claim 1; An image generating unit for generating an image of a subject from light incident through the zoom lens system; A camera-shake correction actuator for correcting camera-shake by rotationally driving the optical path changing member; An image shake detecting unit for detecting a shaking motion; A zoom position sensing unit for sensing a zoom position of the zoom lens system; And a processor for driving the camera-shake correction actuator according to information from the shaking motion sensing unit and the zoom position sensing unit. The method according to claim 6, Wherein the camera shake correction actuator is constituted by a voice coil motor, an ultrasonic motor, or a piezoelectric motor. The method according to claim 6, Wherein the shaking motion detecting section comprises a gyro sensor or an angular velocity sensor. The method according to claim 6, Wherein the zoom position sensing unit comprises an MR sensor or a Hall sensor. 10. The method according to any one of claims 6 to 9, Wherein the optical path changing member includes an incident surface on which light is incident, a total reflection surface that changes the path by totally reflecting the incident light, and an exit surface through which light is emitted. 11. The method of claim 10, Wherein the light path changing member comprises a prism. 11. The method of claim 10, Wherein the light path changing member is formed of a lens surface with the incidence surface having a refractive power. 11. The method of claim 10, Wherein the light path changing member is formed of a lens surface on which the exit surface has a refracting power.

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