IMAGE CAPTURING DEVICE AND METHOD TO PERFORM AUTOFOCUS

• US 20200137294A1
• Filed: 10/28/2019
• Published: 04/30/2020
• Est. Priority Date: 10/29/2018
• Status: Active Grant

• Current Assignee: Hanwha Vision Company Limited
• Original Assignee: Hanwha Techwin Co., Ltd. (Hanwha Corporation)
• Inventors: BYUN, Jaewoon, KWON, Youngsang, KIM, Daebong, PARK, Dongjin
• Granted Patent: US 10,958,821 B2
• Time in Patent Office: Days
• CPC Class Codes: 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
• CPC Class Codes: H04N 23/67 Focus control based on electronic image sensor signals
• CPC Class Codes: H04N 23/673 based on contrast or high frequency components of image signals, e.g. hill climbing method

Abstract

An image capturing device including: a lens; a lens driver configured to change a focus position by moving the lens; an image sensor configured to acquire an image signal from light having passed through the lens; a calculator configured to output a focus value determined by passing the image signal from the image sensor through a frequency filter; and a focus controller configured to control the lens driver to move the lens, based on focus values corresponding to focus positions of the lens. The focus controller may receive one or more focus values from the calculator when the lens is positioned at one or more focus positions among the focus positions, and estimate a focus value of another focus position among the focus positions based on the one or more focus positions and the one or more focus values.

Claims

1. An image capturing device comprising:

a lens;

a lens driver configured to change a focus position by moving the lens;

an image sensor configured to acquire an image signal from light having passed through the lens;

a calculator configured to output a focus value determined by passing the image signal from the image sensor through a frequency filter; and

a focus controller configured to control the lens driver to move the lens, based on focus values corresponding to focus positions of the lens,

wherein the focus controller receives one or more focus values from the calculator when the lens is positioned at one or more focus positions among the focus positions, and estimates a focus value of another focus position among the focus positions based on the one or more focus positions and the one or more focus values.

2. The image capturing device of claim 1, wherein the another focus position is adjacent to the one or more focus positions.

3. The image capturing device of claim 1, wherein:

the one or more focus positions comprise a first focus position and a second focus position, and the one or more focus values comprise a first focus value and a second focus value which correspond to the first and second focus positions, respectively; and

the focus controller estimates a third focus value corresponding to a third focus position among the focus positions, based on the first and second focus values.

4. The image capturing device of claim 3, wherein the first focus position, the third focus position, and the second focus position are sequentially located.

5. The image capturing device of claim 4, wherein:

the focus controller estimates a fourth focus value corresponding to a fourth focus position among the focus positions based on the third focus value and the second focus value, receives a fifth focus value from the calculator when the lens is located at a fifth focus position among the focus positions, and corrects the fourth focus value based on the second focus value and the fifth focus value; and

the first focus position, the third focus position, the second focus position, the fourth focus position, and the fifth focus position are sequentially located.

6. The image capturing device of claim 3, wherein:

the frequency filter comprises a first band pass filter and a second band pass filter;

each of the first and second focus values is determined through the first band pass filter; and

the focus controller receives a fourth focus value from the calculator, the fourth focus value being determined through the second band pass filter when the lens is located at the third focus position.

7. The image capturing device of claim 6, wherein the focus controller receives a fifth focus value from the calculator, the fifth focus value being determined through the second band pass filter when the lens is located at a fourth focus position, and estimates a sixth focus value corresponding to the second focus position based on the fourth and fifth focus values.

8. The image capturing device of claim 7, wherein the first focus position, the third focus position, the second focus position, and the fourth focus position are sequentially located.

9. An image capturing device to perform AF (Autofocus), comprising:

a lens;

a lens driver configured to change a focus position by moving the lens;

an image sensor configured to acquire an image signal from light having passed through the lens;

a calculator configured to output a focus value determined by passing the image signal from the image sensor through a frequency filter; and

a focus controller configured to control the lens driver to move the lens based on focus values corresponding to focus positions of the lens,

wherein the focus controller estimates a third focus value corresponding to a third focus position adjacent to a first focus position and a second focus position, based on a first focus value and a second focus value which are outputted from the calculator, when the lens is located at the first and second focus positions.

10. The image capturing device of claim 9, wherein the first focus position, the third focus position, and the second focus position are sequentially located.

11. The image capturing device of claim 10, wherein:

the focus controller estimates a fourth focus value corresponding to a fourth focus position, based on the third focus value and the second focus value; and

the first focus position, the third focus position, the second focus position; and

the fourth focus position are sequentially located.

12. The image capturing device of claim 11, wherein:

the focus controller receives a fifth focus value from the calculator when the lens is located at a fifth focus position, and corrects the estimated fourth focus value based on the second and fifth focus values; and

the first focus position, the third focus position, the second focus position, the fourth focus position, and the fifth focus position are sequentially located.

13. The image capturing device of claim 9, wherein:

the frequency filter comprises a first band pass filter and a second band pass filter; and

the calculator outputs the first and second focus values using the first band pass filter, and outputs a fourth focus value using the second band pass filter when the lens is located at the third focus position.

14. A method for adjusting a focus of a lens, comprising:

determining focus values corresponding to focus positions of the lens; and

determining whether the lens is located at an in-focus position, based on the focus values, wherein the determining of the focus values comprises;

acquiring a first focus value by passing an image signal through a frequency filter, the image signal being acquired when the lens is located at a first focus position;

acquiring a second focus value by passing an image signal through the frequency filter, the image signal being acquired when the lens is located at a second focus position different from the first focus position; and

estimating a third focus value corresponding to a third focus position adjacent to the first and second focus positions, based on the first and second focus values.

15. The method of claim 14, wherein the first focus position, the third focus position, and the second focus position are sequentially located.

16. The method of claim 15, further comprising estimating a fourth focus value corresponding to a fourth focus position, based on the third focus value and the second focus value,

wherein the first focus position, the third focus position, the second focus position and the fourth focus position are sequentially located.

17. The method of claim 14, wherein:

the frequency filter comprises a first band pass filter and a second band pass filter;

the first and second focus values are acquired through the first band pass filter; and

the method further comprises acquiring a fourth focus value using the second band pass filter when the lens is located at the third focus position.