Automatic focusing method for camera performing additional scanning

1. An automatic focusing method, the method comprising:

setting one mode among a macro mode and a normal mode, wherein the macro mode is appropriate for photographing a subject within a first distance and the normal mode is appropriate for photographing a subject beyond the first distance;

setting a boundary region for auto-focusing in a first region corresponding to the one mode, the boundary region starting at a boundary position beyond an ending position of the first region and apart from the ending position by a number of driving steps of a focus motor times two;

performing the auto-focusing in the first region corresponding to the one mode;

determining whether a position of a focus lens is within the boundary region;

if the position of the focus lens is within the boundary region, determining whether a final position of the focus lens is set according to the result of the auto-focusing in the first region; and

performing auto-focusing in a second region corresponding to the other mode among the macro mode and the normal mode in the same direction as the auto-focusing in the first region without the user selecting the other mode when the final position of the focus lens is not set in the first region.

2. The automatic focusing method of claim 1 , further comprising:

setting the macro mode, wherein the macro mode is appropriate for photographing a subject within the first distance;

performing for auto-focusing in a first region corresponding to the macro mode;

determining if the final position of the focus lens is set according to the result of the auto-focusing in the first region corresponding to the macro mode; and

performing for auto-focusing in the second region corresponding to the normal mode when the final position of the focus lens is not set in the first region, wherein the normal mode is appropriate for photographing a subject beyond the first distance.

3. The automatic focusing method of claim 1 , further comprising initializing for auto focusing in the first region corresponding to the one mode.

4. The automatic focusing method of claim 1 , wherein the step of performing for auto-focusing in a first region corresponding to the one mode comprises:

outputting a focus value in the first region corresponding to the one mode;

updating a maximum focus value whenever the focus value is output;

determining whether the output focus value has decreased; and

setting the final position of the focus lens to a position of the focus lens corresponding to the updated maximum focus value when the output focus value has decreased.

5. The automatic focusing method of claim 4 , wherein the step of determining whether the output focus value has decreased comprises:

forming a difference between the maximum focus value and the presently output focus value;

comparing the difference with a first reference; and

determining that the presently output focus value has decreased when the difference is greater than the first reference.

6. The automatic focusing method of claim 4 , further comprising:

determining whether a position of the focus lens is within a boundary region when the output focus value has not decreased; and

determining that the final position of the focus lens is not set in the first region when the position of the focus lens is within the boundary region.

7. The automatic focusing method of claim 1 , further comprising initializing for auto-focusing in the second region corresponding to the other mode among the macro mode and the normal mode when the final position of the focus lens is not set in the first region.

8. An automatic focusing apparatus comprising:

an input mechanism that sets one mode among a macro mode and a normal mode, wherein the macro mode is appropriate for photographing a subject within a first distance and the normal mode is appropriate for photographing a subject beyond the first distance; and

a controlling mechanism that:

sets a boundary region for the auto-focusing in a first region corresponding to the one mode, the boundary region starting at a boundary position beyond an ending position of the first region and apart from the ending position by a number of driving steps of a focus motor times two;

performs auto-focusing in the first region corresponding to the one mode;

determines whether a position of a focus lens is within the boundary region;

if the position of the focus lens is within the boundary region, determines whether a final position of the focus lens is set according to the result of the auto-focusing in the first region; and

performs auto-focusing in a second region corresponding to the other mode among the macro mode and the normal mode in the same direction as the auto-focusing in the first region without the user selecting the other mode when the final position of the focus lens is not set in the first region.

9. The automatic focusing apparatus of claim 8 , wherein the input mechanism allows the user to set one mode among the macro mode and the normal mode.

10. The automatic focusing apparatus of claim 8 , wherein:

the input mechanism comprises elements that set the macro mode, wherein the macro mode is appropriate for photographing a subject within the first distance; and

the controlling mechanism comprises elements that:

perform auto-focusing determining in a first region corresponding to the macro mode;

determine if the final position of the focus lens is set according to the result of the auto-focusing in the first region corresponding to the macro mode, and

perform auto-focusing in the second region corresponding to a normal mode when the final position of the focus lens is not set in the first region wherein the normal mode is appropriate for photographing a subject beyond the first distance.

11. The automatic focusing apparatus of claim 8 , wherein the controlling mechanism further comprises elements that initialize auto focusing in the first region corresponding to the one mode.

12. The automatic focusing apparatus of claim 8 , wherein a mechanism that performs auto-focusing in a first region corresponding to the one mode comprises elements that:

output a focus value in the first region corresponding to the one mode;

update a maximum focus value whenever the focus value is output;

determine whether the output focus value has decreased; and

set the final position of the focus lens to a position of the focus lens corresponding to the updated maximum focus value when the output focus value has decreased.

13. The automatic focusing apparatus of claim 12 , wherein the element that determines whether the output focus value has decreased comprises elements that:

form a difference between the maximum focus value and the presently output focus value;

compare the difference with a first reference; and

determine that the presently output focus value has decreased when the difference is greater than the first reference.

14. The automatic focusing apparatus of claim 12 , wherein the control mechanism further comprises elements that:

determine whether a position of the focus lens is within a boundary region when the output focus value has not decreased; and

determine that the final position of the focus lens is not set in the first region when the position of the focus lens is within the boundary region.

15. The automatic focusing apparatus of claim 8 , wherein the controlling mechanism further comprises elements that initialize for auto-focusing in a second region corresponding to the other mode among the macro mode and the normal mode when the final position of the focus lens is not set in the first region.

16. The automatic focusing method of claim 1 , wherein the step of performing for auto-focusing in a first region corresponding to the one mode comprises:

outputting a first focus value by a first number of driving steps of a focus motor;

determining whether the output first focus value has decreased;

outputting a second focus value by a second number of driving steps of the focus motor that is smaller than the first number in a region including a position of the focus lens corresponding to the first focus value when the output first focus value has decreased;

determining whether the output second focus value has decreased; and

setting the final position of the focus lens when the output second focus value has decreased.

17. The automatic focusing apparatus of claim 8 , wherein a mechanism that performs auto-focusing in a first region corresponding to the one mode comprises elements that:

output a first focus value by a first number of driving steps of a focus motor;

determine whether the output first focus value has decreased;

output a second focus value by a second number of driving steps of the focus motor that is smaller than the first number in a region including a position of the focus lens corresponding to the first focus value when the output first focus value has decreased;

determine whether the output second focus value has decreased; and

set the final position of the focus lens when the output second focus value has decreased.