Thin dual-aperture zoom digital camera

Abstract

A dual-aperture zoom camera comprising a Wide camera with a respective Wide lens and a Tele camera with a respective Tele lens, the Wide and Tele cameras mounted directly on a single printed circuit board, wherein the Wide and Tele lenses have respective effective focal lengths EFL.sub.W and EFL.sub.T and respective total track lengths TTL.sub.W and TTL.sub.T and wherein TTL.sub.W/EFL.sub.W>1.1 and TTL.sub.T/EFL.sub.T<1.0. Optionally, the dual-aperture zoom camera may further comprise an optical OIS controller configured to provide a compensation lens movement according to a user-defined zoom factor (ZF) and a camera tilt (CT) through LMV=CT*EFL.sub.ZF, where EFL.sub.ZF is a zoom-factor dependent effective focal length.

Claims

1. A dual-aperture zoom camera, comprising: a) a Wide camera with a respective Wide lens and a Tele camera with a respective Tele lens, wherein the Wide and Tele lenses have respective effective focal lengths EFL.sub.W and EFL.sub.T and respective total track lengths TTL.sub.W and TTL.sub.T, and wherein TTL.sub.W/EFL.sub.W>1.1 and TTL.sub.T/EFL.sub.T<1.0; b) an optical image stabilization (OIS) mechanism configured to provide a compensation for lens movement (LMV) of the Wide and Tele lenses according to a camera tilt (CT) input and a user-defined zoom factor (ZF), wherein LMV=CTEFL.sub.ZF and wherein CT is a camera tilt in radians and EFL.sub.ZF is a zoom-factor dependent effective focal length in millimeters.

2. The dual-aperture zoom camera of claim 1, wherein for ZF=1, EFL.sub.ZF=EFL.sub.W.

3. The dual-aperture zoom camera of claim 1, wherein EFL.sub.T/EFL.sub.W=e, wherein e is in the range 1.3-2.0 and wherein for ZF=e, EFL.sub.ZF=EFL.sub.T.

4. The dual-aperture zoom camera of claim 1, wherein EFL.sub.T/EFL.sub.W=e, wherein e is in the range 1.3-2.0 and wherein for ZF in the range 1<ZF<e, EFL.sub.ZF=ZFEFL.sub.W.

5. The dual-aperture zoom camera of claim 1, wherein EFL.sub.T/EFL.sub.W=e, wherein e is in the range 1.3-2.0 and wherein for ZF>e, EFL.sub.ZF=EFL.sub.T.

6. The dual-aperture zoom camera of claim 1, wherein a ratio TTL.sub.T/TTL.sub.W is in the range 1.0-1.25.

7. The dual-aperture zoom camera of claim 1, having a dual-aperture zoom camera height of less than 7 mm and wherein EFL.sub.T>6.1 mm.

8. The dual-aperture zoom camera of claim 1, wherein the Tele lens comprises in order from an object side to an image side, a first lens element with positive refractive power and a second lens element with negative refractive power, wherein the first lens element has a convex object-side surface and a convex or concave image-side surface, an Abbe number greater than 50 and a focal length f1 smaller than TTL/2, and wherein the second lens element is a meniscus lens having a convex object-side surface and an Abbe number smaller than 30.

9. A method for manufacturing a dual-aperture zoom camera comprising: a) providing a Wide camera having a Wide lens with an effective focal length (EFL) EFL.sub.W and a total track length (TTL) TTL.sub.W; b) providing a Tele camera having a Tele lens with an effective focal length EFL.sub.T and a total track length TTL.sub.T, wherein TTL.sub.W/EFL.sub.W>1.1 and wherein TTL.sub.T/EFL.sub.T<1.0; and c) configuring an optical image stabilization (OIS) controller of the dual-aperture zoom camera to compensate lens movement (LMV) of the Wide and Tele lenses according to a camera tilt (CT) input and a user-defined zoom factor (ZF); wherein LMV=CTEFL.sub.ZF and wherein CT is in radians and EFL.sub.ZF is a zoom-factor dependent effective focal length in millimeters.

10. A method of compensating lens movement in a dual-aperture zoom camera comprising a Wide camera with a respective Wide lens and a Tele camera with a respective Tele lens, wherein the Wide and Tele lenses have respective effective focal lengths EFL.sub.W and EFL.sub.T and respective total track lengths TTL.sub.W and TTL.sub.T, the method comprising using an optical image stabilization (OIS) controller of the dual-aperture zoom camera for compensating lens movement (LMV) of the Wide and Tele lenses according to a camera tilt (CT) input and a user-defined zoom factor (ZF), wherein LMV=CTEFL.sub.ZF and wherein CT is in radians and EFL.sub.ZF is a zoom-factor dependent effective focal length in millimeters.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Non-limiting embodiments are herein described, by way of example only, with reference to the accompanying drawings, wherein:

(2) FIG. 1 shows definitions of TTL and EFL;

(3) FIG. 2 shows shadowing and light-blocking problems caused by height differences between Wide and Tele cameras in a dual-aperture camera;

(4) FIG. 3 shows an embodiment of a dual-aperture camera disclosed herein;

(5) FIG. 4 shows schematically in a block diagram details of the camera embodiment of FIG. 3.

DETAILED DESCRIPTION

(6) The present inventors have determined that camera movement (due to exemplarily, but not limited to mishaps such as drop impact) can be avoided or minimized by mounting the two cameras directly on a single printed circuit board and by minimizing a distance d therebetween. FIG. 3 shows an embodiment of a dual-aperture camera 300 that includes two cameras 302 and 304 mounted directly on a single printed circuit board 305. Each camera includes a lens assembly (respectively 306 and 308), an actuator (respectively 310 and 312) and an image sensor (respectively 314 and 316). The two actuators are rigidly mounted on a rigid base 318 that is flexibly connected to the printed board through flexible elements 320. Base 318 is movable by an OIS mechanism (not shown) controlled by an OIS controller 402 (FIG. 4). The OIS controller is coupled to, and receives camera tilt information from, a tilt sensor (exemplarily a gyroscope) 404 (FIG. 4). More details of an exemplary OIS procedure as disclosed herein are given below with reference to FIG. 4. The two cameras are separated by a small distance d, typically 1 mm. This small distance between cameras also reduces the perspective effect, enabling smoother zoom transition between cameras.

(7) In some embodiments and optionally, a magnetic shield plate as described in co-owned U.S. patent application Ser. No. 14/365,718 titled Magnetic shielding between voice coil motors in a dual-aperture camera, which is incorporated herein by reference in its entirety, may be inserted in the gap with width d between the Wide and Tele cameras.

(8) In general, camera dimensions shown in FIG. 3 may be as follows: a length L of the camera (in the Y direction) may vary between 13-25 mm, a width W of the camera (in the X direction) may vary between 6-12 mm, and a height H of the camera (in the Z direction, perpendicular to the X-Y plane) may vary between 4-12 mm. More typically in a smartphone camera disclosed herein, L=18 mm, W=8.5 mm and H=7 mm.

(9) The present inventors have further determined that in some embodiments, the problem posed by the large difference in the TTL/EFL ratio of known dual-aperture camera Tele and Wide lenses may be solved through use of a standard lens for the Wide camera (TTL.sub.W/EFL.sub.W>1.1, typically 1.3) and of a special Tele lens design for the Tele camera (TTL.sub.T/EFL.sub.T<1, typically 0.87). Exemplarily, the special Tele lens design may be as described in co-owned and U.S. patent application Ser. No. 14/367,924, titled Miniature telephoto lens assembly, which is incorporated herein by reference in its entirety. A Tele lens assembly described in detail therein comprises five lenses that include, in order from an object side to an image side: a first lens element with positive refractive power having a convex object-side surface, a second lens element with negative refractive power having a thickness d.sub.2 on an optical axis and separated from the first lens element by a first air gap, a third lens element with negative refractive power and separated from the second lens element by a second air gap, a fourth lens element having a positive refractive power and separated from the third lens element by a third air gap, and a fifth lens element having a negative refractive power, separated from the fourth lens element by a fourth air gap, the fifth lens element having a thickness d.sub.5 on the optical axis. The lens assembly may exemplarily have an F number (F#)<3.2. In an embodiment, the focal length of the first lens element f1 is smaller than TTL.sub.T/2, the first, third and fifth lens elements have each an Abbe number greater than 50, the second and fourth lens elements have each an Abbe number smaller than 30, the first air gap is smaller than d.sub.2/2, the third air gap is greater than TTL.sub.T/5 and the fourth air gap is smaller than 1.5d.sub.5. In some embodiments, the surfaces of the lens elements may be aspheric.

(10) Using a Tele lens designed as above, TTL.sub.T is reduced to 70.87=6.09 mm, leading to a camera height of less than 7 mm (acceptable in a smartphone). The height difference (vs. the Wide camera) is also reduced to approx. 1.65 mm, causing less shadowing and light blocking problems.

(11) In some embodiments of a dual-aperture camera disclosed herein, the ratio e=EFL.sub.T/EFL.sub.W is in the range 1.3-2.0. In some embodiments, the ratio TTL.sub.T/TTL.sub.W<0.8e. In some embodiments, TTL.sub.T/TTL.sub.W is in the range 1.0-1.25. In general, in camera embodiments disclosed herein, EFL.sub.W may be in the range 2.5-6 mm and EFL.sub.T may be in the range 5-12 mm.

(12) With reference now to FIG. 4, in operation, tilt sensor 404 dynamically measures the camera tilt (which is the same for both the Wide and Tele cameras). OIS controller 402, which is coupled to the actuators of both cameras through base 318, receives a CT input from the tilt sensor and a user-defined zoom factor, and controls the lens movement of the two cameras to compensate for the tilt. The LMV is exemplarily in the X-Y plane. The OIS controller is configured to provide a LMV equal to CT*EFL.sub.ZF, where EFL.sub.ZF is chosen according to the user-defined ZF. In an exemplary OIS procedure, when ZF=1, LMV is determined by the Wide camera EFL.sub.W (i.e. EFL.sub.ZF=EFL.sub.W and LMV=CT*EFL.sub.W). Further exemplarily, when ZF>e (i.e. ZF>EFL.sub.T/EFL.sub.W), LMV is determined by EFL.sub.T (i.e. EFL.sub.ZF=EFL.sub.T and LMV=CT*EFL.sub.T). Further exemplarily yet, for a ZF between 1 and e, the EFL.sub.ZF may shift gradually from EFL.sub.W to EFL.sub.T according to EFL.sub.ZF=ZF*EFL.sub.W. As mentioned, the OIS procedure above is exemplary, and other OIS procedures may use other relationships between EFL.sub.ZF and ZF to provide other type of LMV.

(13) While this disclosure has been described in terms of certain embodiments and generally associated methods, alterations and permutations of the embodiments and methods will be apparent to those skilled in the art. The disclosure is to be understood as not limited by the specific embodiments described herein, but only by the scope of the appended claims.