Time of flight sensor, a three-dimensional imaging device using the same, and a method for driving the three-dimensional imaging device
A time of flight (ToF) sensor includes: a first pixel including a first photogate to receive light reflected by an object and generate a first phase signal, and a second photogate to generate a second phase signal having a phase difference of 180 degrees with respect to the first phase signal; a second pixel including a third photogate to receive the reflected light and generate a third phase signal different from the first phase signal and a fourth photogate to generate a fourth phase signal having a phase difference of 180 degrees with respect to the third phase signal; a first signal output unit to output the first and second phase signals; and a second signal output unit to output the third and fourth phase signals, wherein the first, second, third and fourth photogates output the first to fourth phase signals during a frame period.
1. A three-dimensional (3D) imaging device, comprising:
a light source configured to emit light to an object;
a light source driver configured to supply a driving voltage to the light source;
a time of flight (ToF) sensor including a plurality of first pixels configured to receive light reflected by the object and output a first phase signal and a second phase signal having a phase difference of 180 degrees and a plurality of second pixels configured to receive the light reflected by the object and output a third phase signal and a fourth phase signal having a phase difference of 180 degrees;
a sensor driver configured to control driving of the ToF sensor by supplying a driving signal to the ToF sensor;
a phase pattern processor including a plurality of analog-to-digital converters to receive and convert the first phase signal, the second phase signal, the third phase signal, and the fourth phase signal into digital phase values and a phase pattern arranger that latches the digital phase values into a line memory to generate a phase pattern image by arranging the digital phase values in one frame; and
a depth information generator configured to generate depth information of the object based on the one frame of the phase pattern image.
2. The 3D imaging device of claim 1 , wherein each of the plurality of first pixels includes a first photogate configured to output the first phase signal and a second photogate configured to output the second phase signal, and
each of the plurality of second pixels includes a third photogate configured to output the third phase signal and a fourth photogate configured to output the fourth phase signal.
3. The 3D imaging device of claim 2 , wherein the sensor driver supplies the first photogate with a first photogate driving signal for driving the first photogate corresponding to one of initial 0-degree, 90-degree, 180-degree, and 270-degree phases of the light emitted from the light source, supplies the second photogate with a second photogate driving signal for driving the second photogate with a phase difference of 180 degrees with respect to the first photogate driving signal, supplies the third photogate with a third photogate driving signal for driving the third photogate with a phase difference of 90 degrees with respect to the first photogate driving signal, and supplies the fourth photogate with a fourth photogate driving signal for driving the fourth photogate with a phase difference of 180 degrees with respect to the third photogate driving signal.
4. The 3D imaging device of claim 3 , wherein the ToF sensor outputs the first phase signal, the second phase signal, the third phase signal, and the fourth phase signal during one frame period.
5. The 3D imaging device of claim 4 , wherein the phase pattern processor receives and converts the first phase signal, the second phase signal, the third phase signal, and the fourth phase signal into digital phase values of 0 degrees, 90 degrees, 180 degrees, and 270 degrees and generates the phase pattern image of one frame by arranging the digital phase values of 0 degrees, 90 degrees, 180 degrees, and 270 degrees.
6. The 3D imaging device of claim 5 , wherein the phase pattern processor generates the phase pattern image of one frame for acquiring depth information of an X-axis direction by arranging the digital phase values of 0 degrees, 90 degrees, 180 degrees, and 270 degrees according to an input mode or a preset mode.
7. The 3D imaging device of claim 6 , wherein the phase pattern processor arranges the digital phase values of 0 degrees and 180 degrees in even-numbered rows of the phase pattern image of one frame and arranges the digital phase values of 90 degrees and 270 degrees in odd-numbered rows of the phase pattern image of one frame.
8. The 3D imaging device of claim 6 , wherein the phase pattern processor arranges the digital phase values of 0 degrees and 270 degrees in even-numbered columns of the phase pattern image of one frame and arranges the digital phase values of 90 degrees and 180 degrees in odd-numbered columns of the phase pattern image of one frame.
9. The 3D imaging device of claim 5 , wherein the phase pattern processor generates the phase pattern image of one frame for acquiring depth information of a Y-axis direction by arranging the digital phase values of 0 degrees, 90 degrees, 180 degrees, and 270 degrees according to an input mode or a preset mode.
10. The 3D imaging device of claim 9 , wherein the phase pattern processor arranges the digital phase values of 0 degrees, 90 degrees, 180 degrees, and 270 degrees in all rows of the phase pattern image of one frame.
11. The 3D imaging device of claim 9 , wherein the phase pattern processor arranges the digital phase value of 0 degrees in a first column of the phase pattern image of one frame, arranges the digital phase value of 180 degrees in a second column of the phase pattern image of one frame, arranges the digital phase value of 270 degrees in a third column of the phase pattern image of one frame, and arranges the digital phase value of 90 degrees in a fourth column of the phase pattern image of one frame.
12. The 3D imaging device of claim 5 , wherein the phase pattern processor generates the phase pattern image of one frame for acquiring depth information of X-axis and Y-axis directions by arranging the digital phase values of 0 degrees, 90 degrees, 180 degrees, and 270 degrees according to an input mode or a preset mode.
13. The 3D imaging device of claim 12 , wherein the phase pattern processor arranges the digital phase values of 0 degrees, 90 degrees, 180 degrees, and 270 degrees in all rows of the phase pattern image of one frame and arranges the digital phase values of 0 degrees, 90 degrees, 180 degrees, and 270 degrees in all columns of the phase pattern image of one frame.
14. A method of driving a three-dimensional (3D) imaging device, the method comprising:
receiving, by a first photogate and a second photogate of a first pixel, light and outputting a first phase signal and a second phase signal having a phase difference of 180 degrees;
receiving, by a third photogate and a fourth photogate of a second pixel, the light and outputting a third phase signal and a fourth phase signal having a phase difference of 180 degrees;
receiving and converting the first phase signal, the second phase signal, the third phase signal, and the fourth phase signal into digital phase values and latching the digital phase values into a line memory to generate a phase pattern image by arranging the digital phase values in one frame; and
generating depth information of an object based on the one frame of the phase pattern image.
15. The method of claim 14 , wherein the first photogate outputs the first phase signal corresponding to one of initial 0-degree, 90-degree, 180-degree, and 270-degree phases of light emitted from a light source,
the third photogate outputs the third phase signal corresponding to one of initial 0-degree, 90-degree, 180-degree, and 270-degree phases of the light emitted from the light source,
the first phase signal and the third phase signal have a phase difference of 90 degrees, and
the second phase signal and the fourth phase signal have a phase difference of 90 degrees.
16. The method of claim 14 , wherein the first phase signal, the second phase signal, the third phase signal, and the fourth phase signal are output during one frame period.
17. The method of claim 16 , wherein the receiving and converting of the first phase signal, the second phase signal, the third phase signal, and the fourth phase signal into the digital phase values comprises receiving and converting the first phase signal, the second phase signal, the third phase signal, and the fourth phase signal into digital phase values of 0 degrees, 90 degrees, 180 degrees, and 270 degrees.
18. The method of claim 17 , wherein the generating of the phase pattern image comprises generating a phase pattern image of one frame by arranging the digital phase values of 0 degrees, 90 degrees, 180 degrees, and 270 degrees.
19. The method of claim 18 , wherein the phase pattern image of one frame is generated to acquired depth information of an X-axis direction by arranging the digital phase values of 0 degrees, 90 degrees, 180 degrees, and 270 degrees according to an input mode or a preset mode.
20. The method of claim 18 , wherein the phase pattern image of one frame is generated to acquired depth information of a Y-axis direction by arranging the digital phase values of 0 degrees, 90 degrees, 180 degrees, and 270 degrees according to an input mode or a preset mode.