Method for controlling flash apparatus, wherein preliminary flashing is performed one time

• US 20040119879A1
• Filed: 12/09/2003
• Published: 06/24/2004
• Est. Priority Date: 12/14/2002
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Techwin Co., Ltd. (Hanwha Corporation)
• Inventors: Lee, Seok-Goun
• Granted Patent: US 7,420,613 B2
• Time in Patent Office: Days
• US Class Current: 348/371
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 23/74 by influencing the scene brightness using illuminating means

Abstract

A flash apparatus to perform preliminary flashing, detect an average brightness of surroundings in synchronization with a periodic signal subsequent to the preliminary flashing, and set main flashing time according to the detected average brightness, is controlled by controlling the flash apparatus to start preliminary flashing at a point earlier than a first point at which either a rising edge or a falling edge of a first pulse of the periodic signal is generated, detecting a first average brightness of surroundings at the first point, controlling the flash apparatus to terminate the preliminary flashing at a point later than the first point, detecting a second average brightness of surroundings at a second point at which either a rising edge or a falling edge of a second pulse subsequent to the first pulse of the periodic signal is generated, setting the main flashing time according to the detected first and second average brightness, and controlling the flash apparatus to perform main flashing according to the set main flashing time.

Claims

1. A method of performing preliminary flashing for a camera, the method comprising:

generating a first readout signal pulse;

performing preliminary flashing at a time t1 after the rising edge of the first readout signal;

generating the rising edge of a second readout signal pulse at a time t2 that is after time t1;

measuring a first average brightness at time t2;

ending preliminary flashing at a time t3 after time t2;

generating the rising edge of a third readout signal pulse at a time t4; and

measuring a second average brightness at time t4.

2. The method of claim 1, wherein the rising edge of the readout signal pulses are generated after the falling edge of vertical sync signals.

3. The method of claim 1, wherein the first average brightness is measured exactly at time t2.

4. The method of claim 1, wherein the second average brightness is measured exactly at time t4.

5. The method of claim 1, further comprising:

if the first average brightness is greater than an upper limit and the second average brightness is less than a lower limit, then redoing the process, beginning with the first step.

6. The method of claim 1, further comprising:

if the first average brightness is greater than an upper limit and the second average brightness is greater than a lower limit, then setting main flashing time in accordance with the second average brightness.

7. The method of claim 1, further comprising:

if the first average brightness is less than an upper limit and the second average brightness is greater than a lower limit, then setting main flashing time in accordance with the average of the first average brightness and the second average brightness.

8. The method of claim 7, wherein the main flashing time is inversely proportional to the average of the first average brightness and the second average brightness.

9. The method of claim 1, further comprising:

if the first average brightness is less than an upper limit and the second average brightness is less than a lower limit, then setting main flashing time in accordance with the first average brightness.

10. The method of claim 1, further comprising:

performing main flashing.

11. The method of claim 10, wherein the main flashing is performed a set time after t3.

12. The method of claim 11, wherein the set time is 760 ms.

13. The method of claim 1, wherein the camera is a digital camera.

14. A method of performing preliminary flashing for a camera, the method comprising:

generating a first readout signal pulse;

performing preliminary flashing at a time t1 after the rising edge of the first readout signal;

generating the falling edge of a second readout signal pulse at a time t2 that is after time t1;

measuring a first average brightness at time t2;

ending preliminary flashing at a time t3 after time t2;

generating the falling edge of a third readout signal pulse at a time t4; and

measuring a second average brightness at time t4.

15. The method of claim 14, wherein the time t1 is after the falling edge of the first readout signal.

16. The method of claim 14, further comprising:

if the first average brightness is greater than an upper limit and the second average brightness is less than a lower limit, then redoing the process, beginning with the first step.

17. The method of claim 14, further comprising:

if the first average brightness is greater than an upper limit and the second average brightness is greater than a lower limit, then setting main flashing time in accordance with the second average brightness.

18. The method of claim 14, further comprising:

if the first average brightness is less than an upper limit and the second average brightness is less than a lower limit, then setting main flashing time in accordance with the first average brightness.

19. The method of claim 14, further comprising:

if the first average brightness is less than an upper limit and the second average brightness is greater than a lower limit, then setting main flashing time in accordance with the average of the first average brightness and the second average brightness;

20. The method of claim 19, wherein the main flashing time is inversely proportional to the average of the first average brightness and the second average brightness.

21. The method of claim 14, further comprising:

performing main flashing.

22. The method of claim 21, wherein the main flashing is performed a set time after t3.

23. A method of performing preliminary flashing for a camera, the method comprising:

generating a first readout signal pulse;

performing preliminary flashing at a time t1 after the rising edge of the first readout signal;

generating the rising edge of a second readout signal pulse at a time t2 that is after time t1;

measuring a first average brightness at time t2;

ending preliminary flashing at a time t3 after time t2;

generating the falling edge of a third readout signal pulse at a time t4; and

measuring a second average brightness at time t4.

24. A method of performing preliminary flashing for a camera, the method comprising:

generating a first readout signal pulse;

performing preliminary flashing at a time t1 after the rising edge of the first readout signal;

generating the falling edge of a second readout signal pulse at a time t2 that is after time t1;

measuring a first average brightness at time t2;

ending preliminary flashing at a time t3 after time t2;

generating the rising edge of a third readout signal pulse at a time t4; and

measuring a second average brightness at time t4.

25. A camera comprising:

an image sensing portion;

an image signal processing portion;

a light emitting device;

a light emission driving portion;

a microcontroller that generates a control signal and transmits the control signal to the light emission driving portion; and

a timing signal generator that generates both a read-out signal and a vertical sync signal and transmits each of the read-out signal and the vertical sync signal to both the image sensing portion and the microcontroller.

26. The camera of claim 25, wherein the read-out signal comprises substantially smaller pulses than the vertical sync signal.

27. The camera of claim 25, wherein the rising edge of each read-out signal is generated after the falling edge of each vertical sync signal.

28. The camera of claim 25, wherein the camera is a digital camera.