TRACKING DEVICE, AUTOMATIC FOCUSING DEVICE, AND CAMERA

• US 20090153666A1
• Filed: 05/30/2007
• Published: 06/18/2009
• Est. Priority Date: 06/28/2006
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Muramatsu, Keiko, Takeuchi, Hiroshi
• Granted Patent: US 8,253,800 B2
• Time in Patent Office: Days
• US Class Current: 348/169
• CPC Class Codes: G01S 3/7864 T.V. type tracking systems
• CPC Class Codes: G02B 7/28 Systems for automatic generation of focusing signals
• CPC Class Codes: G03B 13/36 Autofocus systems
• CPC Class Codes: H04N 23/61 based on recognised objects
• CPC Class Codes: H04N 23/635 Region indicators; Field of view indicators
• CPC Class Codes: H04N 23/671 in combination with active ranging signals, e.g. using light or sound signals emitted toward objects
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 23/73 by influencing the exposure time

Abstract

A tracking device includes: a light measurement device for light measuring an object; a focus detection device for performing focus detection of the object by an optical system; and a tracking control device for tracking the object based on light measurement information from the light measurement device and focus detection information from the focus detection device corresponding to the light measurement information.

Claims

1. A tracking device comprising:

a light measurement device for light measuring an object;

a focus detection device for performing focus detection of the object by an optical system; and

a tracking control device for tracking the object based on light measurement information from the light measurement device and focus detection information from the focus detection device corresponding to the light measurement information.

2. The tracking device according to claim 1, wherein the light measurement information is luminance or color information of the object.

3. The tracking device according to claim 1, wherein

the light measurement device and the focus detection device respectively obtains the light measurement information and the focus detection information at a plurality of positions in a field of the optical system;

and

the tracking control device determines a position having information with high matching degree of the light measurement information and the focus detection information with respect to the object of the light measurement information and the focus detection information at the plurality of positions as a position where the object exists.

4. The tracking device according to claim 3, wherein the tracking control device performs the tracking based on focus detection information detected at a focus detection position in the vicinity of a light measurement position when the light measurement position at where the light measurement device obtains the light measurement information and the focus detection position at where the focus detection device obtains the focus detection information are different.

5. The tracking device according to claim 1, wherein the tracking control device sets reference information for tracking the object based on the light measurement information and the focus detection information.

6. The tracking device according to claim 5, wherein the reference information is a range of an image including the object of the light measurement information.

7. The tracking device according to claim 1, wherein the tracking control device sets the reference information for tracking the object based on the light measurement information and the focus detection information, and changes size of the reference information according to change of the focus detection information.

8. The tracking device according to claim 7, further comprising:

a determination device for determining whether the object is moving closer to or moving away from the optical system based on the focus detection information;

wherein

the tracking control device changes the size of the reference information based on a determination result of the determination device.

9. The tracking device according to claim 1, wherein the tracking control device selects a candidate of the object based on a hue value of the reference information.

10. The tracking device according to claim 9, wherein the tracking control device determines the object based on the focus detection information from the selected candidate of the object.

11. An automatic focusing device comprising:

the tracking device according claim 1; and

a focus control device for obtaining a driving amount of a focus adjustment optical system for adjusting a focus position of the optical system according to the focus detection information obtained by the focus detection device;

wherein

the tracking control device tracks an object, which focus detection is performed by the focus detection device.

12. The automatic focusing device according to claim 11, wherein the tracking control device corrects the focus detection information according to an amount the focus adjustment optical system is driven.

13. The automatic focusing device according to claim 11, wherein the tracking control device predicts movement of a focusing plane of the optical system involved in the movement of the object, and corrects the focus detection information according to the predicted result.

14. A camera equipped with the automatic focusing device according to claim 11.

15. A tracking method comprising:

a light measurement step of light measuring an object;

a focus detection step of performing focus detection of the object by an optical system; and

a tracking step of tracking the object based on at least one of a light measurement result in the light measurement step or a focus detection result in the focus detection step.

16. The tracking method according to claim 15, wherein in the tracking step, reference information for tracking the object is set based on at least one of the light measurement result or the focus detection result.

17. The tracking method according to claim 16, wherein in the tracking step, size of the reference information is changeable according to the focus detection result.

18. The tracking method according to claim 15, wherein

in the light measurement step and the focus detection step, the light measurement result and the focus detection result are obtained at a plurality of positions in a field of the optical system;

and

in the tracking step, a position having high matching degree of the light measurement result and the focus detection result with respect to the object of the light measurement results and the focus detection results at the plurality of positions is determined as a position where the object exists.

19. The tracking method according to claim 18, wherein in the tracking step, when the light measurement position at where the light measurement result is obtained and a focus detection position at where the focus detection result is obtained are different, the tracking is performed based on focus detection result detected at the focus detection position in the vicinity of a light measurement position.

20. The tracking method according to claim 16, further comprising:

a determination step of determining whether the object is moving closer to or moving away from the optical system;

wherein

in the tracking step, the size of the reference information is changed based on a determination result in the determination step.

21. The tracking method according to claim 16, wherein in the tracking step, a candidate of the object is selected based on a hue value of the reference information.

22. The tracking method according to claim 21, wherein in the tracking step, the object is determined based on the focus detection result from the selected candidate of the object.