Focus adjustment apparatus and focus adjustment method

• US 9,083,881 B2
• Filed: 04/28/2014
• Issued: 07/14/2015
• Est. Priority Date: 03/15/2010
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Hamada, Masataka, Won, Jong-hoon
• Primary Examiner(s): Daniels, Anthony J
• Application Number:
  US14/263,091
• Publication Number:
  US 20140232926A1
• Time in Patent Office: 442 Days
• Field of Search: 348/345, 348/349, 348354-356
• US Class Current: 1/1
• 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 23/675 comprising setting of focusing regions

Abstract

Focus adjustment apparatus and methods for effectively auto-focusing on a subject by adaptively changing a shape of a focus area according to a determined image condition, and in particular, setting the focus area in a shape of which a width of an upper part is narrow according to the condition.

Claims

1. A focus adjustment apparatus comprising:

a focus lens;

a focus lens driver configured to drive the focus lens in an optical axis direction;

an image pickup unit configured to generate an image signal by converting image light incident through the focus lens into an electrical signal;

a determiner configured to determine at least one condition;

a focus area setting unit configured to set a focus area in a shape of which a width of an upper part is narrower than a lower part according to the determined condition; and

a controller configured to control movement of the focus lens to adjust a focus on an image signal corresponding to the set focus area;

an Auto Focus (AF) evaluation value deriver configured to derive a plurality of AF evaluation values using image signals respectively corresponding to a plurality of focus lens positions; and

a peak value determiner configured to determine a peak AF evaluation value according to the AF evaluation values;

wherein the determining a condition includes determining whether the peak AF evaluation value is low by comparing the peak AF evaluation value to a reference peak value, and

the focus area setting unit sets a first focus area if the peak AF evaluation value is not low and sets a second focus area, which is greater than the first focus area and has a shape of which a width of an upper part is narrower than a lower part, if the peak AF evaluation value is low.

2. A focus adjustment apparatus comprising:

a focus lens;

a focus lens driver configured to drive the focus lens in an optical axis direction;

an image pickup unit configured to generate an image signal by converting image light incident through the focus lens into an electrical signal;

a determiner configured to determine whether a current mode is a specific mode;

a focus area setting unit configured to set a first focus area, if the current mode is not the specific mode, and set a second focus area, which is greater than the first focus area and has a shape of which a width of an upper part is narrower than a lower part, if the current mode is the specific mode; and

a controller configured to control movement of the focus lens to adjust a focus on an image signal corresponding to the set focus area.

3. The focus adjustment apparatus of claim 2, wherein the specific mode is at least one of a night scene mode, a portrait mode, and a moving picture mode.

4. A focus adjustment apparatus comprising:

a focus lens;

a focus lens driver configured to drive the focus lens in an optical axis direction;

an image pickup unit configured to generate an image signal by converting image light incident through the focus lens into an electrical signal;

an Auto Focus (AF) evaluation value deriver configured to derive AF evaluation values respectively corresponding to a plurality of focus lens positions at each of a plurality of first focus areas including at least one area of a scene of the image pickup unit using image signals respectively corresponding to the plurality of focus lens positions and first focus areas; and

a peak value determiner configured to determine peak AF evaluation values respectively corresponding to the plurality of first focus areas according to the AF evaluation values respectively corresponding to each of the plurality of first focus areas;

a determiner configured to determine at least one condition;

a focus area setting unit configured to set a focus area, which is greater than one of the first focus areas and has a shape of which a width of an upper part is narrower than a lower part, according to the determined condition; and

a controller configured to control movement of the focus lens to adjust a focus on an image signal corresponding to the set focus area.

5. The focus adjustment apparatus of claim 4, further comprising a main subject determiner configured to select a greatest one of the peak AF evaluation values and determine a subject corresponding to the selected peak AF value as a main subject.

6. The focus adjustment apparatus of claim 5, wherein the determining a condition includes determining whether the selected peak AF evaluation value is low by comparing the selected peak AF evaluation value to a reference peak value, and

the focus area setting unit sets a first focus area if the selected peak AF evaluation value is not low and sets a second focus area, which is greater than the first focus area and has a shape of which a width of an upper part is narrower than a lower part, if the selected peak value of the AF evaluation value is low.

7. The focus adjustment apparatus of claim 6, wherein the second focus area includes the first focus area.

8. A focus adjustment method comprising:

generating an image signal by converting image light incident through a focus lens into an electrical signal;

deriving a plurality of Auto Focus (AF) evaluation values using image signals respectively corresponding to a plurality of first lens positions; and

determining a peak AF evaluation value according to the AF evaluation values,

determining whether the peak AF evaluation value is low by comparing the peak AF evaluation value to a reference peak value;

setting a first focus area if the peak AF value is not low, and setting a second focus area, which is greater than the first focus area and has a shape of which a width of an upper part is narrower than a lower part, if the peak value is low; and

moving the focus lens to adjust a focus on an image signal corresponding to the set focus area.

9. A focus adjustment method comprising:

generating an image signal by converting image light incident through a focus lens into an electrical signal;

determining whether a current mode is a specific mode;

setting a first focus area if the current mode is not the specific mode, and setting a second focus area, which is greater than the first focus area and has a shape of which a width of an upper part is narrower than a lower part if the current mode is the specific mode; and

moving the focus lens to adjust a focus on an image signal corresponding to the set focus area.

10. The focus adjustment method of claim 9, wherein the specific mode is at least one of a night scene mode, a portrait mode, and a moving picture mode.

11. A focus adjustment method comprising:

generating an image signal by converting image light incident through a focus lens into an electrical signal;

determining at least one condition;

setting a focus area in a shape of which a width of an upper part is narrower than a lower part according to the determined condition;

moving the focus lens to adjust a focus on an image signal corresponding to the set focus area;

deriving Auto Focus (AF) evaluation values respectively corresponding to a plurality of focus lens positions at each of a plurality of first focus areas using image signals respectively corresponding to the plurality of focus lens positions and first focus areas; and

determining peak AF evaluation values respectively corresponding to the plurality of first focus areas from the AF evaluation values respectively corresponding to the plurality of first focus areas.

12. The focus adjustment method of claim 11, further comprising selecting a greatest one of the peak AF evaluation values and determining a subject corresponding to the selected peak value as a main subject.

13. The focus adjustment method of claim 11, further comprising:

selecting a greatest one of the peak AF evaluation values;

determining whether the selected peak AF evaluation value is low by comparing the selected peak AF evaluation value to a reference peak value, and

setting a first focus area corresponding to the selected peak AF evaluation value if the selected peak AF evaluation value is not low, and setting a second focus area which is greater than the first focus area and has a shape of which a width of an upper part is narrower than a lower part if the selected peak AF evaluation value is low.

14. The focus adjustment method of claim 13, wherein the second focus area includes the first focus area.

15. A focus adjustment apparatus comprising:

a focus lens;

a focus lens driver configured to drive the focus lens in an optical axis direction;

an image pickup unit configured to generate an image signal by converting image light incident through the focus lens into an electrical signal;

an Auto Focus (AF) evaluation value deriver configured to derive a plurality of AF evaluation values using image signals respectively corresponding to a plurality of focus lens positions;

a peak value determiner configured to determine a peak AF evaluation value according to the AF evaluation values;

a determiner configured to determine whether the peak AF evaluation value is low by comparing the peak AF evaluation value to a reference peak value;

a focus area setting unit configured to set a first focus area if the peak AF evaluation value is not low and a second focus area if the peak AF evaluation value is low; and

a controller configured to control movement of the focus lens to adjust a focus on an image signal corresponding to one of the first focus area and the second focus area;

wherein the second focus area is an area which expands vertically from the first focus area.

16. The focus adjustment apparatus of claim 15, wherein the focus area setting unit sets the second focus area in one of shape of which an upper part protrudes, a shape of the letter I, and a shape of a cross.

17. The focus adjustment apparatus of claim 15, further comprising a position sensor configured to sense whether the focus adjustment apparatus is oriented in a horizontal or vertical direction relative the ground,

wherein the focus area setting unit sets the second focus area which expands vertically from the first focus area and is longer than the first focus area in a vertical direction relative the ground if the focus adjustment apparatus is oriented in either of the horizontal or vertical direction.

18. A focus adjustment apparatus of comprising:

a focus lens;

a focus lens driver configured to drive the focus lens in an optical axis direction;

an image pickup unit configured to generate an image signal by converting image light incident through the focus lens into an electrical signal;

an Auto Focus (AF) evaluation value deriver is configured to derive a plurality of AF evaluation values respectively corresponding to a plurality of focus lens positions at each of a plurality of first focus areas including at least one area of a scene of the image pickup unit using image signals respectively corresponding to the plurality of focus lens positions and first focus areas;

a peak value determiner configured to determine peak AF evaluation values respectively corresponding to the plurality of first focus areas according to the AF evaluation values respectively corresponding to each of the plurality of first focus areas;

a determiner configured to determine whether a selected peak AF value is low by comparing the selected peak AF value to a reference peak value;

a focus area setting unit configured to set a first focus area if the peak AF evaluation value is not low and set a second focus area if the peak AF evaluation value is low; and

a controller configured to control movement of the focus lens to adjust a focus on an image signal corresponding to one of the first focus area and the second focus area,

wherein the second focus area is an area which expands vertically from the first focus area; and

the selected peak AF value is a peak AF evaluation value of the first focus area that is determined to have a main subject of the scene of the image pickup device.

19. A focus adjustment apparatus comprising:

a focus lens;

a focus lens driver configured to drive the focus lens in an optical axis direction;

an image pickup unit configured to generate an image signal by converting image light incident through the focus lens into an electrical signal;

a determiner configured to determine a specific mode;

a focus area setting unit configured to set a first focus area if the current mode is not the specific mode and a second focus area if the current mode is the specific mode; and

a controller configured to control movement of the focus lens to adjust a focus on an image signal corresponding to one of the first focus area and the second focus area,

wherein the second focus area has a shape of which a width of an upper part is narrower than a lower part, and

the specific mode is at least one of a night scene mode, a portrait mode, and a moving picture mode.

20. A focus adjustment apparatus comprising:

a focus lens;

a focus lens driver configured to drive the focus lens in an optical axis direction;

an image pickup unit configured to generate an image signal by converting image light incident through the focus lens into an electrical signal;

a determiner configured to determine whether the brightness of the image signal is low by comparing brightness information of the image signal to reference brightness information;

a focus area setting unit configured to set a first focus area if the brightness of the image signal is not low and a second focus area if the brightness of the image signal is low; and

a controller configured to control movement of the focus lens to adjust a focus on an image signal corresponding to one of the first focus area and the second focus area;

wherein the second focus area is an area which expands vertically from the first focus area.