# US 10,455,141 B2 · Auto-focus method and apparatus and electronic device

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- Number: US 10,455,141 B2
- Document ID: US10455141B2
- Status: Granted
- Kind: B2
- Application number: 16/142,996
- Filed: 2018-09-26
- Published: 2019-01-24
- Granted: 2019-10-22
- Earliest claimed: 2018-09-26
- Assignees: Huawei Technologies Co., Ltd.
- Applicants: Huawei Technologies Co., Ltd.
- Inventors: Cheng Du; Jin Wu; Wei Luo; Bin Deng
- Web page: https://patentgrep.com/patent/US10455141B2

## CPC

- G03B 13/36: Autofocus systems
- G02B 7/09: adapted for automatic focusing or varying magnification
- G02B 7/38: measured at different points on the optical axis {, e.g. focussing on two or more planes and comparing image data}
- G06T 7/55: from multiple images
- G06T 7/73: using feature-based methods
- H04N 23/45: for generating image signals from two or more image sensors being of different type or operating in different modes, e.g. with a CMOS sensor for moving images in combination with a charge-coupled device [CCD] for still images
- G03B 19/023: {Multi-image cameras}
- G06T 2207/10012: Stereo images
- G06T 2207/10028: Range image; Depth image; 3D point clouds
- G06T 2207/30201: Face
- G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

An auto-focus method including at a same moment, collecting a first image of a first object using a first image shooting unit, collecting a second image of the first object using a second image shooting unit, calculating M pieces of first depth information of M same feature point pairs in corresponding areas in the first image and the second image, determining whether confidence of the M pieces of first depth information is greater than a threshold, obtaining focusing depth information according to N pieces of first depth information in the IM pieces of first depth information when the confidence of the M pieces of first depth information is greater than the threshold, obtaining a target position of a first lens of the first image shooting unit according to the focusing depth information, and controlling the first lens to move to the target position.

## Claims

### Claim 1

An auto-focus method, comprising:
collecting a first image of a first object using a first camera including a first lens, the first image collected with the first lens at a first position:
collecting a second image of the first object using a second camera including a second lens, the second image collected with the second lens at a second position:
obtaining focusing depth information of the first image and the second image; obtaining a target position of the first lens of the first camera according to the focusing depth information;
controlling the first lens to move to the target position;
controlling the second lens of the second camera to move to a third position;
collecting a third image of the first object using the first camera when the first lens is at the target position;
performing a check on the focusing depth information based on the first image, the third image, and a fourth image collected by the second camera with the second lens at the third position; and
collecting a fifth image of the first object using the first camera with the lens at the target position when the check is successful.

### Claim 2 (depends on 1)

The method of claim 1, further comprising controlling the second lens of the second camera to move to a position corresponding to the target position.

### Claim 3 (depends on 1)

The method of claim 1, further comprising shooting an image in response to a user operation.

### Claim 4 (depends on 1)

The method of claim 1, wherein an optical axis of the first camera is parallel to an optical axis of the second camera.

### Claim 5 (depends on 1)

The method of claim 1, wherein the first object is a face.

### Claim 6

An electronic device, comprising:
a first camera having a first lens;
a second camera having a second lens, the first camera and the second camera being disposed on a same plane of the electronic device;
a first actuator; and
a processor coupled to the first camera, the second camera, and the first actuator, the processor configured to:
cause the first camera to collect a first image of a first object when the first lens is at a first position;
cause the second camera to collect a second image of the first object when the second lens is at a second position;
obtain focusing depth information of the first image and the second image;
obtain a target position of the first lens of the first camera according to the focusing depth information;
control the first actuator to move the first lens to the target position;
control movement of the second lens to move the second lens to a third position;
cause the first camera to collect a third image of the first object when the first lens is at the target position;
perform a check on the focusing depth information based on the first image, the third image, and a fourth image collected by the second camera with the second lens at the third position; and
cause the first camera to collect a fifth image of the first object using the first camera with the lens at the target position when the check is successful.

### Claim 7 (depends on 6)

The electronic device of claim 6, wherein the first camera and the second camera are disposed on a rear cover of the electronic device.

### Claim 8 (depends on 6)

The electronic device of claim 6, wherein a parameter of the first camera is the same as a parameter of the second camera.

### Claim 9 (depends on 8)

The electronic device of claim 8, wherein the first camera and the second camera have a same focal length.

### Claim 10 (depends on 6)

The electronic device of claim 6, wherein an optical axis of the first camera is parallel to an optical axis of the second camera.

### Claim 11 (depends on 6)

The electronic device of claim 6, wherein the first actuator is a voice coil motor (VCM).

### Claim 12 (depends on 7)

The electronic device of claim 7, wherein the voice coil motor (VCM) comprises:
a magnet set; and
a coil fixed in the magnet set using two spring plates, the coil configured to generate a magnetic field when the coil is powered on, the magnetic field interacting with the magnet set to move the coil upward, the first lens being locked in the coil such that the coil and the first lens move together, and the coil configured to return back to an original position under an elastic force of the spring plate when the coil is powered off.

### Claim 13 (depends on 6)

The electronic device of claim 6, wherein the electronic device is a mobile phone.

### Claim 14 (depends on 1)

The method of claim 1, further comprising determining a first contrast of the first image, a second contrast of the second image, and a third contrast of the fourth image.

### Claim 15 (depends on 14)

The method of claim 14, wherein the performing the check includes determining whether the third contrast is less than the second contrast.

### Claim 16 (depends on 15)

The method of claim 15, wherein performing the check further includes determining whether the first contrast is less than the second contrast.

### Claim 17 (depends on 16)

The method of claim 16, further comprising determining that the check is successful when the third contrast is less than the second contrast and the first contrast is less than the second contrast.