Method and device of measuring the distance to an object
To measure the distance to points on an object by radiating a periodic amplitude-modulated optical signal to the object and detecting the phase difference between the radiated optical signal and a reflected optical signal from the object, a first photo-detection control signal is generated to control the radiation of the optical signal. A mask signal is generated such that the mask signal is activated at least during a shuttering duration for resetting the voltage level at a sensing node (associated with an operation of a previous frame). A second photo-detection control signal is generated based on the first photo-detection signal and the mask signal such that the second photo-detection signal is deactivated or masked at least during the shuttering duration.
1. A device for measuring the distance to m×n points on an object, the device radiating a periodic amplitude-modulated optical signal to the object and detecting the phase difference between the radiated optical signal and a reflected optical signal from the object, the device comprising:
a timing controller configured to generate a first photo-detection control signal to control the radiation of the optical signal and a mask signal that is activated at least during a shuttering duration for resetting the voltage level at a sensing node;
a photo-gate controller configured to generate a second photo-detection control signal based on the first photo-detection control signal and the mask signal such that the second photo-detection control signal is deactivated or masked at least during the shuttering duration; and
a pixel array including a plurality m×n of pixels, wherein each of m and n is a natural number, each pixel including a photo-gate that receives the second photo-detection control signal to sense the reflected optical signal.
2. The device of claim 1 , further comprising:
a row decoder configured to receive a row control signal from the timing controller to generate a decoded row address, select a row of the pixel array in response to the decoded row address, and provide the decoded row address to the photo-gate controller.
3. The device of claim 2 , wherein the photo-gate controller is configured to perform a Boolean logic operation on the decoded row address, the first photo-detection control signal and the mask signal to generate the second photo-detection control signal.
4. The device of claim 1 , further comprising:
a correlated double sampling (CDS) unit configured to perform CDS to compensate the detected phase difference for a reset voltage level.
5. The device of claim 4 , wherein the mask signal is further activated at least during an activated duration of a reset control signal to detect the reset voltage level.
6. The device of claim 4 , wherein the CDS unit is configured to detect a signal voltage level at the sensing node during a first duration, the signal voltage level associated with the reflected optical signal, activate a reset control signal to reset the sensing node during a second duration, and detect the reset voltage level at the sensing node during a third duration.
7. The device of claim 6 , wherein the mask signal is further activated at least during the first duration, the second duration and the third duration.
8. The device of claim 4 , further comprising:
an analog-to-digital converter configured to convert an analog signal to a digital signal, the CDS unit outputting the analog signal.
9. The device of claim 4 , wherein the CDS unit outputs a digital signal.
10. The device of claim 1 , wherein the photo-gate controller is configured to perform a Boolean logic operation at least on the first photo-detection control signal and the mask signal to generate the second photo-detection control signal.