Auto focus adjusting method, auto focus adjusting apparatus, and digital photographing apparatus including the same

• US 9,667,856 B2
• Filed: 09/09/2015
• Issued: 05/30/2017
• Est. Priority Date: 08/05/2011
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Hamada, Masataka
• Primary Examiner(s): Hsu, Amy
• Application Number:
  US14/848,863
• Publication Number:
  US 20160073009A1
• Time in Patent Office: 629 Days
• CPC Class Codes: G02B 7/38 measured at different points on the optical axis , e.g. focussing on two or more planes and comparing image data
• CPC Class Codes: G03B 3/10 Power-operated focusing
• CPC Class Codes: H04N 23/63 by using electronic viewfinders
• CPC Class Codes: H04N 23/663 for controlling interchangeable camera parts 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
• CPC Class Codes: H04N 23/73 by influencing the exposure time

Abstract

An auto focus (AF) adjusting method, an AF adjusting apparatus, and a digital photographing apparatus including the same, the AF adjusting apparatus including: an AF calculator for calculating focus detection evaluation values; a peak detector for detecting a peak position of the focus detection evaluation values; and a speed calculator for calculating a moving speed of a subject by using the peak position. When continuous photographing of still images is performed, the peak detector detects the peak position in an image pickup interval before a light exposure preparation interval for image capturing, and the focus lens driver performs moving body compensation driving for compensating for a focal position by using a moving speed calculated in the light exposure preparation interval before capturing starts.

Claims

1. A photographing apparatus comprising:

a focus lens;

a focus lens driver for driving the focus lens;

an image pickup device for generating an image signal by picking up light which has passed through the focus lens;

a processor for determining a focal position of the focus detection;

a shutter for controlling light exposure of the image pickup device;

an iris; and

an iris driving actuator for driving the iris,

wherein the processor determines a driving direction of the focus lens based on at least two image frames which are obtained on different focal positions from each other before capturing of a still image to be stored in a memory card,

the at least two image frames are obtained while displaying a live-view image, and

the iris driving actuator opens the iris while obtaining the at least two image frames, and adjusts the iris to a calculated iris value before the still image to be stored in the memory card is captured.

2. The photographing apparatus of claim 1, wherein when it is determined that a movement of the object exists, the at least two image frames are obtained.

3. The photographing apparatus of claim 1, wherein the movement of the subject includes a movement in an optical axis direction.

4. The photographing apparatus of claim 1, when a continuous photographing for continuously capturing still images is performed:

after a previous still image capturing and before a light exposure preparation interval for a subsequent still image capturing, the processor determines the driving direction; and

the focus lens driver moves the focus lens by the determined driving direction before the subsequent still image capturing starts.

5. The photographing apparatus of claim 1, wherein the processor calculates a moving speed of a subject based on the at least two image frames, and the focus lens driver moves the focus lens in order to obtain the at least two image frames based on the calculated moving speed.

6. The photographing apparatus of claim 1, wherein the processor determines the driving direction based on a pre-stored information related to focusing.

7. The photographing apparatus of claim 1, wherein the shutter is a mechanical shutter including a front curtain and a rear curtain.

8. The photographing apparatus of claim 1, wherein the shutter is an electronic front curtain shutter including an electronic front curtain for beginning light exposure by resetting electric charges and a mechanical rear curtain for ending the light exposure.

9. The photographing apparatus of claim 1, wherein the moving of the focus lens in the determined driving direction is performed in an interval before beginning to drive an electronic front curtain for the subsequent image capturing after stopping driving for selectively reading electric charges from the image pickup device.

10. The photographing apparatus of claim 1, wherein the shutter is a global shutter including an electronic front curtain for beginning light exposure by resetting electric charges and an electronic rear curtain for ending the light exposure.

11. The photographing apparatus of claim 1, wherein the moving the focus lens in the determined driving direction is performed in an interval before beginning to drive an electronic front curtain for image capturing after stopping driving for selectively reading electric charges from the image pickup device.

12. The photographing apparatus of claim 1, wherein the at least two image frames are obtained while displaying a live-view image, the photographing apparatus ends the displaying of the live-view image before a subsequent still image capturing, and the moving the focus lens in the determined driving direction is performed in an interval before beginning the image capturing after ending the displaying of the live-view image.

13. The photographing apparatus of claim 1, wherein the detection of the focal position is performed by driving the focus lens back and forth.

14. The photographing apparatus of claim 1, wherein, during a continuous photographing, detecting the focal position multiple times is performed in an image pickup interval before a light exposure preparation interval, and a moving speed of the subject is calculated from a result of the detecting of the focal position multiple times.

15. The photographing apparatus of claim 1, wherein, during a continuous photographing, the focal position detection is performed at least once in a image pickup interval before a light exposure preparation interval for every still image capturing, and a moving speed of the subject is calculated by using a focal position result detected in the image pickup interval for current still image capturing and a focal position result detected in the image pickup interval for the previous still image capturing.

16. The photographing apparatus of claim 1, wherein during a continuous photographing, a moving speed of the subject is determined by using the moving speed of the subject acquired before the continuous photographing starts or a moving speed of the subject obtained in the previous still image capturing during the continuous photographing.

17. The photographing apparatus of claim 1, wherein, when a moving speed of the subject before a continuous photographing starts is acquired, the acquired moving speed and the moving speed of the subject acquired during the continuous photographing are used to predict a focal position in the subsequent still image capturing, and when the moving speed of the subject before the continuous photographing starts is not acquired, the moving speed of the subject acquired during the continuous photographing is used to predict a focal position in the subsequent image capturing.

18. The AF adjusting apparatus of claim 1, wherein, when a moving speed of the subject is acquired, the moving the focus lens in the determined driving direction is performed by predicting the focal position according to movement of the subject in an interval from a light exposure end time to an image pickup start time before the light exposure preparation interval for the subsequent still image capturing by using the acquired moving speed.

19. A method for controlling a photographing apparatus comprising:

obtaining at least two image frames on different focal positions from each other before capturing of a still image to be stored in a memory card;

determining a driving direction of a focus lens based on the obtained at least two image frames;

capturing a still image to be stored in a memory card,

wherein the at least two image frames are obtained while displaying a live-view image, and

an iris is open while the at least two image frames are obtained, and is adjusted to a calculated iris value before the still image to be stored in the memory card is captured.