Imaging apparatus and method for controlling same

• US 9,525,813 B2
• Filed: 04/30/2014
• Issued: 12/20/2016
• Est. Priority Date: 05/09/2013
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Sakaguchi, Takeshi
• Primary Examiner(s): Flohre, Jason
• Assistant Examiner(s): Tejano, Dwight C
• Application Number:
  US14/265,881
• Publication Number:
  US 20140333823A1
• Time in Patent Office: 965 Days
• Field of Search: 348/222.1, 348/340, 348/345
• US Class Current: 1/1
• CPC Class Codes: H04N 23/12 with one sensor only
• CPC Class Codes: H04N 23/663 for controlling interchangeable camera parts based on electronic image sensor signals
• CPC Class Codes: H04N 23/672 based on the phase difference signals
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 25/134 based on three different wavelength filter elements
• CPC Class Codes: H04N 25/704 Pixels specially adapted for focusing, e.g. phase difference pixel sets

Abstract

A control device acquires a focus detection signal from a pixel portion of the imaging element so as to detect a focus state by phase difference detection. A camera control unit performs focus adjustment control by the drive control of a focus lens constituting an imaging optical system. The camera control unit performs exposure control for adjusting the brightness of an object in the focus area to an appropriate level, and determines whether or not the brightness level of the object in the focus area is saturated based on the focus detection signal. When the exposure state during a focus adjustment operation is not in an appropriate state, the camera control unit calculates an exposure correction value and determines whether or not the exposure correction value falls within the exposure control range. When the exposure correction value falls within the exposure control range, the exposure state is readjusted.

Claims

1. A control device comprising:

a detecting unit configured to acquire an output signal from an imaging unit having an imaging element so as to perform phase difference type focus detection, wherein the imaging element outputs a signal photoelectrically converted at a predetermined cycle;

a determination unit configured to determine whether or not an output signal for phase difference type focus detection from the imaging unit is saturated; and

a control unit configured to perform exposure control of the imaging element and to perform focus adjustment control of an imaging optical system with respect to an object by acquiring detection information from the detecting unit,

wherein the control unit performs the focus adjustment control so as to move a focus lens comprised in the imaging optical system from a first position to a second position different from the first position, and performs exposure control when the determination unit determines that the output signal for the phase difference type focus detection from the imaging unit is saturated, and

wherein the determination unit determines whether or not the output signal for the phase difference type focus detection from the imaging unit which is acquired when the focus lens is positioned at the first position is saturated and determines whether or not the output signal for the phase difference type focus detection from the imaging unit which is acquired when the focus lens is positioned at the second position is saturated.

2. The control device according to claim 1, wherein the detecting unit acquires the focus detection signal output from a pixel portion, which corresponds to a target area on an imaging screen, of the imaging element so as to perform phase difference detection, and the control unit determines whether or not an output signal from the imaging unit related to the target area is saturated.

3. The control device according to claim 2, wherein the control unit performs exposure control when a correction value for not saturating the output signal falls within a control range whereas performs focus determination for an object corresponding to the target area when a correction value for not saturating the output signal falls outside the control range.

4. The control device according to claim 1, wherein the pixel portion of the imaging unit has a microlens and a plurality of photoelectric conversion units and outputs a focus detection signal.

5. The control device according to claim 1, wherein the control unit performs exposure control in accordance with a user'"'"'s release operation and then performs focus adjustment.

6. The control device according to claim 5, wherein, when the control unit determines that the output signal from the imaging unit is saturated after first focus adjustment performed after the user'"'"'s release operation, the control unit performs exposure control so as not to saturate the output signal from the imaging unit.

7. The control device according to claim 1, wherein the exposure control is at least one of charge accumulation time control of the imaging element, gain control of the output signal, and aperture control of the imaging optical system.

8. The control device according to claim 1, wherein, when the change of an effective open F-number of the imaging optical system upon the focus adjustment control is equal to or greater than a threshold value, the control unit calculates a correction value in the exposure state.

9. The control device according to claim 1, wherein the saturation determination by the determination unit is performed for an output signal for the phase difference type focus detection from the imaging unit prior to a computation of a phase difference.

10. The control device according to claim 1, wherein the determination unit acquires detection information obtained by the focus detecting unit and determines that the output signal from the imaging unit is saturated when the saturation level of the focus detection signal is greater than a determination threshold value.

11. The control device according to claim 8, wherein, when the saturation level of the focus detection signal is equal to or less than a determination threshold value and the change of the effective open F-number of the imaging optical system is less than a threshold value, the determination unit performs focus determination for an object corresponding to the target area.

12. The control device according to claim 1, wherein the determination unit performs first determination processing for determining the saturation level of the focus detection signal on the pixel-by-pixel basis and second determination processing for determining the saturation level of the focus detection signal on the row-by-row basis of the target area.

13. The control device according to claim 12, wherein the determination unit calculates a saturation determination value by comparing the saturation level with a first threshold value in the second determination processing and determines that the brightness level of an object corresponding to the target area is saturated when the sum of the saturation determination values is greater than a second threshold value.

14. The control device according to claim 1, wherein the control unit uses a predetermined correction value for the focus adjustment control.

15. The control device according to claim 1, wherein, when the determination unit determines that the output signal for the phase difference type focus detection from the imaging unit is saturated, the control unit performs exposure control so as not to saturate the output signal from the imaging unit.

16. A control device comprising:

a detecting unit configured to acquire an output signal from an imaging unit having an imaging element so as to perform phase difference type focus detection, wherein the imaging element outputs a signal photoelectrically converted at a predetermined cycle; and

a control unit configured to perform charge accumulation time control of the imaging element, gain control of the output signal, and aperture control of an imaging optical system and to perform focus adjustment control of the imaging optical system with respect to an object by acquiring detection information from the detecting unit,

wherein the control unit performs charge accumulation time control of the imaging element and gain control of the output signal in priority over aperture control of the imaging optical system depending on the level of the output signal from the imaging unit while repeating the focus adjustment control.

17. The control device according to claim 16, wherein the detecting unit acquires the focus detection signal output from a pixel portion, which corresponds to a target area on an imaging screen, of the imaging element so as to perform phase difference detection, and the control unit controls exposure depending on the level of the output signal from the imaging unit related to the target area.

18. The control device according to claim 16, wherein the pixel portion of the imaging unit has a microlens and a plurality of photoelectric conversion units and outputs a focus detection signal.

19. The control device according to claim 16, wherein the control unit performs exposure control in accordance with a user'"'"'s release operation and then performs focus adjustment.

20. The control device according to claim 19, wherein the control unit performs the charge accumulation time control of the imaging element and the gain control of the output signal in priority over the aperture control of the imaging optical system depending on the level of the output signal from the imaging unit after first focus adjustment performed after the user'"'"'s release operation.

21. A control method to be executed by a control device that comprises:

a detecting unit configured to acquire an output signal from an imaging unit having an imaging element so as to perform phase difference type focus detection, wherein the imaging element outputs a signal photoelectrically converted at a predetermined cycle;

a determination unit configured to determine whether or not an output signal for phase difference type focus detection from the imaging unit is saturated; and

a control unit configured to perform exposure control of the imaging element and to perform focus adjustment control of an imaging optical system with respect to an object by acquiring detection information from the detecting unit,

wherein the method comprising;

performing, by the control unit, the focus adjustment control so as to move a focus lens comprised in the imaging optical system from a first position to a second position different from the first position, and performing exposure control when the determination unit determines that the output signal for the phase difference type focus detection from the imaging unit is saturated, and

determining, by the determination unit, whether or not the output signal for the phase difference type focus detection from the imaging unit which is acquired when the focus lens is positioned at the first position is saturated, and determining whether or not the output signal for the phase difference type focus detection from the imaging unit which is acquired when the focus lens is positioned at the second position is saturated.

22. A control method to be executed by a control device that comprises:

a detecting unit configured to acquire an output signal from an imaging unit having an imaging element so as to perform phase difference type focus detection, wherein the imaging element outputs a signal photoelectrically converted at a predetermined cycle; and

a control unit configured to perform charge accumulation time control of the imaging element, gain control of the output signal, and aperture control of an imaging optical system and to perform focus adjustment control of the imaging optical system with respect to an object by acquiring detection information from the detecting unit,

wherein the method comprising;

performing, by the control unit, the charge accumulation time control of the imaging element and the gain control of the output signal in priority over the aperture control of the imaging optical system depending on the level of the output signal from the imaging unit while repeating the focus adjustment control.