Depth sensing using a time of flight system including a scanning beam in combination with a single photon avalanche diode array
A depth camera assembly (DCA) includes a light generator emitting a beam of light into a local area and a detector. The detector captures light from the beam reflected by objects in the local area to a portion of an array of pixels that each include a single photon avalanche diode (SPAD). The location of the portion of the array is based in part on the angle of the beam emitted from the projector. The DCA identifies a set of pixels of the array corresponding to the portion and selectively retrieves current generated from the reflected light by the pixels in the portion of the array without retrieving current generated by pixels in other portions of the array.
1. A detector comprising:
an array of pixels comprising a plurality of columns of pixels and a plurality of rows of pixels, each pixel including as single photon avalanche diode (SPAD) coupled to a comparator configured to generate a particular value in response to current generated by the SPAD included in the pixel from light incident on the SPAD exceeding a threshold value;
switches coupled to each SPAD pixel of the array,
an aggregator coupled to the switches, the aggregator configured to sum current received from SPAD pixels coupled to the aggregator by activated switches for each time instant to generate an analog output signal and to convert, for each time instant, the analog output signal into a digital timestamp signal associated with a time instant, the aggregator comprising a comparator coupled to each switch coupled to a SPAD pixel of the array and configured to combine current generated by SPAD pixels coupled to activated switches and to generate a specific value in response to the combined current exceeding a threshold value and a time to digital converter (TDC) coupled to the comparator and configured to generate a digital representation of a time when the time to digital converter received the specific value from the comparator.
2. The detector of claim 1 , wherein the switches are configured to receive a control signal identifying rows and columns of the array of pixels coupled to switches to be activated.
3. The detector of claim 1 , wherein the switches are configured to receive a control signal identifying pairs of a row of the array of pixels and a corresponding column of the array of coupled to switches to be activated.
4. The detector of claim 1 , wherein the switches are configured to receive a control signal that deactivates a switches coupled to the SPAD pixel of the array to decouple the SPAD pixel of the array from the aggregator and that activates switches coupled to an alternative SPAD pixel of the array to couple the alternative SPAD pixel to the aggregator.
5. The detector of claim 1 , wherein the TDC is configured to output the digital representation of the time when the TDC received the specific value from the comparator.
6. The detector of claim 5 , wherein the TDC is configured to output the digital representation of the time when the TDC received the specific value from the comparator to a controller configured to determine depth information for one or more objects in a local area that reflected outgoing light from a transmitter based on the time when the TDC received the specific value from the comparator.