Methods of controlling image sensors using modified rolling shutter methods to inhibit image over-saturation

Patent metadata

Field	Value
Publication number	US-8988598-B2
Application number	US-201213617867-A
Country	US
Kind code	B2
Filing date	Sep 14, 2012
Priority date	Sep 14, 2012
Publication date	Mar 24, 2015
Grant date	Mar 24, 2015

Abstract

An image capture device includes an image sensor having an array of pixels therein, which are configured to receive light reflected from an object during an image capture time interval. A light source is provided, which is configured to project light to the object during at least a portion of the image capture time interval. A control circuit/unit is provided, which is electrically coupled to the image sensor and the light source. This control circuit is configured to drive the light source with signals that cause the light source to project light to the object without interruption during at least a first time interval when all rows of a frame of pixels within the array are being sequentially read and during a second time interval when all rows of the frame of pixels within the array are being sequentially read.

First claim

What is claimed is:

1. An image capture device, comprising:
an image sensor having an array of pixels therein configured to receive light reflected from an object during an image capture time interval;
a light source configured to project light to the object during at least a portion of the image capture time interval; and
a control circuit electrically coupled to said image sensor and said light source, said control circuit configured to drive said light source with signals that cause said light source to continuously project light to the object without interruption during at least a first time interval when all rows of a frame of pixels within the array are being sequentially read to yield a first frame of image data and a second time interval when all rows of the frame of pixels within the array are being sequentially read to yield a second frame of image data, wherein said control circuit is further configured to drive said light source with signals that cause said light source to terminate projection of light to the object during a time interval when all of the rows of the frame of pixels within the array are concurrently capturing image data and none of the rows are being read,
wherein the 3D image sensor operates as a rolling shutter image sensor, and
wherein the light source emits modulated light for acquiring depth information of the object.

2. The image capture device of claim 1 , wherein all rows of the frame of pixels are sequentially read and then reset during the first time interval.

3. The image capture device of claim 1 , wherein said control circuit is further configured to drive said image sensor with signals that cause the frame of pixels to collect three-dimensional (3D) depth information associated with the first and second frames of image data during the first and second time intervals and a data integration time interval extending between the first and second time intervals.

4. A method of controlling a 3D image sensor, the method comprising the operations of:
performing a readout operation and a reset operation on first through n-th rows sequentially in a pixel array of the 3D image sensor, where “n” is an integer of at least 2;
turning off a light source of the 3D image sensor for a first duration after completing the readout and reset operations; and
performing the readout and reset operations on the first through n-th rows sequentially in the pixel array of the 3D image sensor after the first duration elapses,
wherein the first duration is included in a photocharge integration duration when all of the rows in the pixel array are concurrently capturing image data and none of the rows are being read,
wherein the 3D image sensor operates as a rolling shutter image sensor, and
wherein the light source emits modulated light for acquiring depth information of the object.

5. The image sensor control method of claim 4 , wherein the operation of performing the readout and reset operations on the first through n-th rows sequentially in the pixel array comprises turning on and off a select transistor and a reset transistor comprised in each pixel in the first through n-th rows sequentially in the pixel array.

6. The image sensor control method of claim 4 , wherein the operation of performing the readout and reset operations on the first through n-th rows sequentially in the pixel array after the first duration elapses comprises turning on and off a select transistor and a reset transistor comprised in each pixel in the first through n-th rows sequentially in the pixel array.

7. The image sensor control method of claim 4 , further comprising the operation of stopping accumulating photocharge at a floating diffusion node comprised in each pixel in the first through n-th rows in the pixel array of the 3D image sensor for a second duration after completing the readout and reset operations.

8. The image sensor control method of claim 7 , wherein the operation of stopping accumulating photocharge at the floating diffusion node comprised in each pixel in the first through n-th rows in the pixel array for the second duration after completing the readout and reset operations comprises simultaneously turning off all transfer transistors comprised in each pixel in the first through n-th rows in the pixel array and simultaneously turning on the transfer transistors after the second duration time elapses.

9. The image sensor control method of claim 7 , wherein the second duration is comprised in the first duration.

10. The image sensor control method of claim 4 , wherein the light source is a light emitting diode.

11. A method of controlling a 3D image sensor, the method comprising the operations of:
performing a readout operation, a reset operation, and an integration operation on first through n-th rows sequentially in a pixel array of the 3D image sensor at least two times, where “n” is an integer of at least 2;
turning off a light source of the 3D image sensor after repeating the readout, reset, and integration operations of the first through n-rows at least two times and turning on the light source after a first duration elapses; and
performing the readout, reset, and integration operations on the first through n-th rows sequentially in the pixel array of the 3D image sensor at least two times after the light source is turned on,
wherein the readout, reset, and integration operations are performed by turning on and off a transfer transistor, a select transistor, and a reset transistor, which are comprised in each cell in the first through n-th rows in the pixel array,
wherein the first duration is included in a photocharge integration duration when all of the rows in the pixel array are concurrently capturing image data and none of the rows are being read,
wherein the 3D image sensor operates as a rolling shutter image sensor, and
wherein the light source emits modulated light for acquiring depth information of the object.

12. The image sensor control method of claim 11 , wherein the operation of performing the readout operation, the reset operation, and the integration operation on the first through n-th rows sequentially in the pixel array at least two times comprises performing the readout, reset, and integration operations on each row four times.

13. The image sensor control method of claim 11 , wherein the operation of performing the readout operation, the reset operation, and the integration operation on the first through n-th rows sequentially in the pixel array at least two times after the light source is turned on comprises performing the readout, reset, and integration operations on each row four times.

14. The image sensor control method of claim 11 , wherein a maximum value of time of the integration operation on each of the first through n-th rows in the pixel array is defined as

t
INTMAX

=

1

4
⁢

⁢

FPS
D

-

t
SR

,

where FPS D is a frame rate of a depth image, 4FPS D is 4 multiplied by FPS D

Assignees

• Ovsiannikov Ilia
• Lee Joon Ho
• Samsung Electronics Co Ltd

Inventors

• Ovsiannikov Ilia
• Lee Joon Ho

Classifications

• H04N23/74 Primary

  by influencing the scene brightness using illuminating means · CPC title

• H04N25/40

  Extracting pixel data from image sensors by controlling scanning circuits, e.g. by modifying the number of pixels sampled or to be sampled · CPC title

• H04N25/53

  Control of the integration time · CPC title

• H04N25/59 Primary

  by controlling the amount of charge storable in the pixel, e.g. modification of the charge conversion ratio of the floating node capacitance · CPC title