FOCUS ADJUSTMENT APPARATUS AND FOCUS ADJUSTMENT METHOD

• US 20110221952A1
• Filed: 03/15/2011
• Published: 09/15/2011
• 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
• Granted Patent: US 8,743,270 B2
• Time in Patent Office: Days
• US Class Current: 348/345
• 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 narrow 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.

2. The focus adjustment apparatus of claim 1, wherein the determining a condition includes determining whether the brightness of the image signal is low by comparing brightness information of the image signal to reference brightness information, and

the focus area setting unit sets a first focus area if the brightness of the image signal 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 narrow, if the brightness of the image signal is low.

3. The focus adjustment apparatus of claim 1, further comprising:

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 narrow, if the peak AF evaluation value is low.

4. The focus adjustment apparatus of claim 1, wherein the determining a condition includes determining whether a current mode is a specific mode, and

the focus area setting unit sets a first focus area if the current mode is not the specific mode 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 narrow, if the current mode is the specific mode.

5. The focus adjustment apparatus of claim 4, wherein the specific mode is at least one of a night scene mode, a portrait mode, and a moving picture mode.

6. The focus adjustment apparatus of claim 1, wherein the focus area setting unit sets the focus area in one of a shape of which an upper part protrudes, a shape of the letter I, and a shape of a cross.

7. The focus adjustment apparatus of claim 1, 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 a focus area having a shape of which a width of an upper part is narrow relative the ground if the focus adjustment apparatus is oriented in either of the horizontal or vertical direction.

8. The focus adjustment apparatus of claim 1, further comprising:

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;

wherein the focus area setting unit sets a focus area, which is greater than the first focus area and has a shape of which a width of an upper part is narrow, according to the determined condition.

9. The focus adjustment apparatus of claim 8, 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.

10. The focus adjustment apparatus of claim 9, 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 narrow, if the selected peak value of the AF evaluation value is low.

11. The focus adjustment apparatus of claim 10, wherein the second focus area includes the first focus area.

12. The focus adjustment apparatus of claim 1, further comprising an operating unit configured to input a signal to adjust at least one of the size and position of the focus area.

13. The focus adjustment apparatus of claim 12, wherein the operating unit has a touch panel configured to input the signal by a user'"'"'s touch.

14. 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 narrow according to the determined condition; and

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

15. The focus adjustment method of claim 14, wherein the determining a condition comprises determining whether brightness of the image signal is low by comparing brightness information of the image signal to reference brightness information, and

the setting of the focus area comprises setting a first focus area if the brightness of the image signal is not low, and if the brightness of the image signal is low, 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 narrow.

16. The focus adjustment method of claim 14, further comprising:

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,

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

the setting of the focus area comprises if the peak AF value is not low setting a first focus area, and if the peak value is low 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 narrow.

17. The focus adjustment method of claim 14, wherein the determining a condition comprises determining whether a current mode is a specific mode, and

the setting of the focus area comprises setting a first focus area if the current mode is not the specific mode, and if the current mode is the specific mode 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 narrow.

18. The focus adjustment method of claim 14, wherein the specific mode is at least one of a night scene mode, a portrait mode, and a moving picture mode.

19. The focus adjustment method of claim 14, wherein the focus area is set in one of a shape of which an upper part protrudes, a shape of the letter I, and a shape of a cross.

20. The focus adjustment method of claim 14, further comprising sensing whether a focus adjustment apparatus is oriented in a horizontal or vertical direction relative the ground,

wherein a focus area having a shape of which a width of an upper part is narrow is set relative the ground if the focus adjustment apparatus is oriented in either of the horizontal or vertical direction.

21. The focus adjustment method of claim 14, further comprising:

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.

22. The focus adjustment method of claim 21, 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.

23. The focus adjustment method of claim 21, 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 narrow if the selected peak AF evaluation value is low.

24. The focus adjustment method of claim 23, wherein the second focus area includes the first focus area.

25. The focus adjustment method of claim 14, further comprising selecting, by a user, at least one of a size and a position of the focus area.

26. The focus adjustment method of claim 25, wherein the focus area is selected by the user'"'"'s touch.

27. A non-transitory computer readable storage medium storing computer readable instructions which, when read by an automated focus adjustment apparatus, cause the focus adjustment apparatus to perform a method comprising:

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

determining a condition;

setting a focus area in a shape of which a width of an upper part is narrow according to the determined condition; and

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