# US 8,786,959 B2 · Auto-focusing camera module and auto-focusing method using same

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- Number: US 8,786,959 B2
- Document ID: US8786959B2
- Status: Granted
- Kind: B2
- Application number: 13/525,371
- Filed: 2012-06-18
- Published: 2013-06-27
- Granted: 2014-07-22
- Earliest claimed: 2011-12-27
- Assignees: Hon Hai Precision Industry Co., Ltd.
- Applicants: Sung-Ching Wu; Ting-Yuan Wu
- Inventors: Sung-Ching Wu; Ting-Yuan Wu
- Web page: https://patentgrep.com/patent/US8786959B2

## CPC

- H04N 23/67: Focus control based on electronic image sensor signals
- G02B 7/36: using image sharpness techniques {, e.g. image processing techniques for generating autofocus signals (image data processing per se G06T; in cameras having a solid state image sensor H04N23/67)}
- H04N 25/615: involving a transfer function modelling the optical system, e.g. optical transfer function [OTF], phase transfer function [PhTF] or modulation transfer function [MTF]
- G02B 27/1013: {for colour or multispectral image sensors, e.g. splitting an image into monochromatic image components on respective sensors (spectral imaging systems G01J)}
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

An auto-focus camera module includes an lens module, an image sensor, a color separation unit, a main processor unit and an image processing unit. The lens module captures an image of object. The image sensor receives the image captured by the lens module. The color separation unit separates the image into red, green and blue colors. The main processor unit calculates MTF values of the sensed image and determines a shooting mode of the AF camera. The image processing unit processes the image according to the MTF values to compensate for any blurring of the image caused by being out of focus. The driving unit drives the lens module to the point of optimal focus on the object according to MTF values.

## Claims

### Claim 1

An AF camera module comprising:
an lens module for capturing an image of an object;
an image sensor aligned with the lens module for sensing the image captured by the lens module;
a color separation unit electrically connected to the image sensor and configured for separating the image sensed by the image sensor into red image, green image and blue image;
a main processor unit electrically connected to the color separation unit, the main processor unit being configured for calculating MTF values of the image and determining a shooting mode of the AF camera, wherein the shooting mode comprises a close shooting mode and a long shooting mode;
an image processing unit electrically connected to the main processor unit, the image processing unit processing the image according to the MTF values calculated by the main processor unit to compensate blurs of the image caused by out of focus when the long shooting mode is selected; and
a driving unit electrically connected to the main processer unit, the driving unit moving the lens module to an optimum focusing position according to the MTF values calculated by the main processor unit when the close shooting mode is selected.

### Claim 2 (depends on 1)

The AF camera module of claim 1, wherein the lens module comprises at least one piece of aspherical lens.

### Claim 3 (depends on 1)

The AF camera module of claim 1, wherein the image sensor comprises a plurality of pixel unit arranged in its sensing area, each pixel unit comprises a red pixel, a green pixel and a blue pixel, the image sensed by the image sensor comprises a plurality of image portions, each of which corresponds to a pixel unit, each image portion of the image is separated into a red color part, a green color part and a blue color part, the red color parts of the image portions construct a red image, the green parts of the image portions construct a green image, and the blue parts of the image portions construct a blue image.

### Claim 4 (depends on 3)

The AF camera module of claim 3, wherein the main processor unit comprises:
a MTF calculating module configured for calculating MTF values of each image portion of the image;
an object distance calculating module configured for calculating an object distance of an object in each image portion of the image according to the MTF values;
an object distance judging module configured for determining the shooting mode according to the object distances;
a blur calculating module configured for comparing the MTF values of each image portion calculated by the MTF calculating module with corresponding predetermined MTF values, generating the differences between the MTF values and the predetermined MTF values, and generating blur quantities of each image portion of the image according to the MTF value differences;
an offset calculating module configured for calculating offset to compensate a blur of each image portion according to the blur quantities;
a focus calculating module configured for calculating an optimum focusing position of the lens module according to the object distance of the object in each image portion; and
a driving distance calculating module configured for calculating a driving distance of the lens module according to the optimum focusing position calculated by the focus calculating module.

### Claim 5 (depends on 4)

The AF camera module of claim 4, wherein the MTF calculating module respectively calculates MTF values of each image portion of the red image, the green image and the blue image.

### Claim 6 (depends on 5)

The AF camera module of claim 5, wherein the object distance judging module analyzes the object distances calculated by the object judging module to get an analysis result, compares the analysis result with a predetermined distance value, and determines the shooting mode.

### Claim 7 (depends on 6)

The AF camera module of claim 6, wherein the object distance judging module analyzes the object distances of the image potions and generates a main object distance representing the object distance of a main object in the image.

### Claim 8 (depends on 7)

The AF camera module of claim 7, wherein the predetermined distance value is 40 cm, if the main object distance is more than 40 cm, the AF camera module is set at the long shooting mode, and if the main object distance is equal to or less than 40 cm, the AF camera module is set at the close shooting mode.

### Claim 9 (depends on 1)

The AF camera module of claim 1, wherein the driving unit is a piezoelectric actuator.

### Claim 10

An AF method, comprising:
reading a sensed image of an object;
separating the image into red image, green image and blue image, wherein the image comprises a plurality of image portions;
calculating MTF values of each image portion of the image;
determining an object distance of the object in each image portion according to the MTF values of each image portion;
analyzing the object distances of the image potions to generate a main object distance representing the object distance of a main object in the image;
selecting a close shooting mode upon a condition that the main object distance is equal to or less than a predetermined distance value;
determining an optimum focusing position of a focusing lens according to the object distance of the object in each image portion;
determining a driving distance of the focusing lens according to the optimum focusing position; and
driving the focusing lens to the optimum focusing position according to the driving distance.

### Claim 11 (depends on 10)

The AF method of claim 10, comprising:
calculating quantity of blurring of each image portion according to the MTF values;
calculating offset for compensating for blurring of each image portion according to the quantity of blurring of each image portion; and
processing each image portion according to the offset of each image portion.