FOCUSING DEVICE, IMAGE PICKUP APPARATUS, AND CONTROL METHOD

Abstract

A focusing device includes a driving unit that drives a focus lens, a control unit, and a storing unit. The control unit controls the driving unit to move the focus lens through a predetermined range, determines a state of focus based on a signal from an image pickup unit, the signal being acquired in association with movement of the focus lens through the predetermined range, and controls the driving unit so that an object's image is in focus. The storing unit stores a position of the focus lens in focus acquired by the control unit. The control unit calculates a datum point of the range of movement of the focus lens, on the basis of the position of the focus lens in the storing unit, and shifts the range of movement of the focus lens in response to the calculated datum point in a direction in which the object moves.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of an electronic camera according to a first exemplary embodiment.

FIG. 2 is a flowchart for an operation of the electronic camera according to the first exemplary embodiment.

FIG. 3 is a flowchart of a subroutine for a continuous AF (step S205) shown in FIG. 2.

FIG. 4 is a flowchart of a subroutine for an AF operation (step S209) shown in FIG. 2.

FIG. 5 illustrates a method for setting a scan range in FIG. 4.

FIG. 6 is a flowchart of a subroutine for a scan (steps S406 and S418) shown in FIG. 4.

FIG. 7 is a flowchart of a subroutine for a focus determination (step S407) shown in FIG. 4.

FIG. 8 is a flowchart for an operation of finding monotone decreasing in a direction approaching infinity.

FIG. 9 is a flowchart for an operation of finding monotone decreasing in a direction toward the closest point.

FIG. 10 is an illustration for describing a concept of determination of a focus evaluated value.

FIG. 11 is a flowchart of a subroutine for a shooting operation shown in FIGS. 2 and 13.

FIG. 12 illustrates how a focus lens moves according to the first exemplary embodiment.

FIG. 13 is a flowchart for a series of operations according to second and third exemplary embodiments.

FIGS. 14A and 14B are flowcharts of a subroutine for an AF operation according to the second exemplary embodiment.

FIGS. 15A and 15B are flowcharts of a subroutine for an AF operation according to the third exemplary embodiment.

FIG. 16 is a flowchart of a subroutine for a shooting operation according to the third exemplary embodiment.

Claims

1. A focusing device comprising: a focus-lens driving unit configured to drive a focus lens;a control unit configured to control the focus-lens driving unit to move the focus lens through a predetermined range, to determine a state of focus on the basis of a signal output from an image pickup unit, the signal being acquired in association with movement of the focus lens through the predetermined range, and to control the focus-lens driving unit so that an image of an object is in focus; anda storing unit configured to store a position of the focus lens in focus acquired by the control unit,wherein the control unit is configured to calculate, on the basis of the position of the focus lens stored in the storing unit, a datum point of the range of movement of the focus lens and to shift the range of movement of the focus lens in response to the calculated datum point in a direction in which the object moves.

2. The focusing device according to claim 1, wherein the control unit is configured to move the range of movement of the focus lens through a range wider than the range of movement based on the calculation of the datum point and to determine the state of focus, when shifting the range of movement of the focus lens in the direction in which the object moves.

3. The focusing device according to claim 1, wherein the control unit is configured to store a position of the focus lens in focus and to calculate the datum point on the basis of the stored position of the focus lens.

4. The focusing device according to claim 1, wherein the control unit is configured to calculate the datum point in a continuous shooting operation.

5. A focusing device comprising: a driving unit configured to drive a focus lens;a control unit configured to control the driving unit to move the focus lens through a predetermined range, to determine a state of focus on the basis of a signal output from an image pickup unit, the signal being acquired in association with movement of the focus lens through the predetermined range, and to control the driving unit so that an image of an object is in focus; andan instructing unit configured to provide an instruction to perform a plurality of imaging operations,wherein, when the instructing unit provides the instruction, the control unit is configured to perform movement of the focus lens by the predetermined range at a predetermined speed before each of the plurality of imaging operations, to determine the state of focus, and to move, before moving the focus lens at the predetermined speed, the focus lens to a position where the state of focus is to be determined at a speed higher than the predetermined speed.

6. The focusing device according to claim 5, wherein the control unit is configured to move the focus lens before each of the movements of the focus lens at the predetermined speed so that the range of the movement at the predetermined speed is shifted in association with movement of the object.

7. An image pickup apparatus comprising: the focusing device according to claim 1; andan image pickup element.

8. An image pickup apparatus comprising: the focusing device according to claim 5; andan image pickup element.

9. A method for controlling a focusing device including a focus-lens driving unit configured to drive a focus lens; a control unit configured to control the focus-lens driving unit to move the focus lens through a predetermined range, to determine a state of focus on the basis of a signal output from an image pickup unit, the signal being acquired in association with movement of the focus lens through the predetermined range, and to control the focus-lens driving unit so that an image of an object is in focus; and a storing unit configured to store a position of the focus lens in focus acquired by the control unit, the method comprising: calculating a datum point of the range of movement of the focus lens for moving the focus lens, on the basis of the position of the focus lens stored in the storing unit; andshifting the range of movement of the focus lens in response to the calculated datum point in a direction in which the object moves.

10. A method for controlling a focusing device including a driving unit configured to drive a focus lens; a control unit configured to control the driving unit to move the focus lens through a predetermined range, to determine a state of focus on the basis of a signal output from an image pickup unit, the signal being acquired in association with movement of the focus lens through the predetermined range, and to control the driving unit so that an image of an object is in focus; and an instructing unit configured to provide an instruction to perform a plurality of imaging operations, the method comprising: when the instruction is provided from the instructing unit,moving the focus lens by the predetermined range at a predetermined speed before each of the plurality of imaging operations and determining the state of focus; andmoving the focus lens to a position where the state of focus is to be determined at a speed higher than the predetermined speed before moving the focus lens at the predetermined speed.

11. A focusing device comprising: a focusing unit configured to detect a state of focus on an object on the basis of a signal output from an image pickup element while scanning in a direction of an optical axis with respect to the object by moving a focus lens and to adjust a position of the focus lens in response to a detected result of the state of focus on the object so that the object is in focus; anda control unit configured to control, in a continuous shooting operation, the focusing unit to perform a scan operation for a current imaging operation by moving the focus lens on the basis of a position of the focus lens at an imaging operation prior to the current imaging and to perform focusing,wherein the control unit is configured to adjust, in the case where a time interval between an immediately preceding imaging operation and the current imaging operation in the continuous shooting operation is longer than each of time intervals between continuous imaging operations up to the immediately preceding imaging operation, the position of the focus lens on the basis of the scan operation a plurality of times in an interval between the immediately preceding imaging operation and the current imaging operation.

12. The focusing device according to claim 11, wherein the control unit is configured to expand, in the case in which the control unit cannot adjust the position of the focus lens on the basis of the scan operation just before the current imaging operation in the continuous shooting operation, a range of the scan operation made by moving the focus lens and adjust the position of the focus lens on the basis of the scan operation through the expanded range.

13. A focusing device comprising: a focusing unit configured to detect a state of focus on an object on the basis of a signal output from an image pickup element while scanning in a direction of an optical axis with respect to the object by moving a focus lens and to adjust a position of the focus lens in response to a detected result of the state of focus on the object so that the object is in focus; anda control unit configured to control, in a continuous shooting operation, the focusing unit to perform a scan operation for a current imaging operation by moving the focus lens on the basis of a position of the focus lens at an imaging operation prior to the current imaging and to perform focusing,wherein the control unit is configured to adjust, in the case where a time interval between an immediately preceding imaging operation and the current imaging operation in the continuous shooting operation is longer than each of time intervals between continuous imaging operations up to the immediately preceding imaging operation, the position of the focus lens on the basis of the scan operation just before the current imaging operation.

14. The focusing device according to claim 13, wherein the control unit is configured to expand, in the case where the control unit cannot adjust the position of the focus lens on the basis of the scan operation just before the current imaging operation in the continuous shooting operation, a range of the scan operation made by moving the focus lens and adjust the position of the focus lens on the basis of the scan operation through the expanded range.

15. An image pickup apparatus comprising the focusing device according to claim 11.

16. An image pickup apparatus comprising the focusing device according to claim 13.