Apparatus for controlling driver current for illumination source

Patent metadata

Field	Value
Publication number	US-2018102407-A1
Application number	US-201715638834-A
Country	US
Kind code	A1
Filing date	Jun 30, 2017
Priority date	Oct 12, 2016
Publication date	Apr 12, 2018
Grant date	—

Abstract

A single photon avalanche diode based range detecting apparatus includes a reference array of single photon avalanche diodes configured to receive light from an illumination source via an internally coupled path. A return array of single photon avalanche diodes is configured to receive light from the illumination source via an external free space path. A calibration pulse generator is configured to generate a calibration signal pulse. Readout circuitry is configured to receive an output of the reference array via a reference signal path, an output of the return array via a return signal path, and an output of the calibration pulse generator via a calibration signal path. The readout circuitry is configured to determine a delay difference value between the reference signal path and the return signal path based on the output of the calibration pulse generator via the calibration signal path.

First claim

What is claimed is:

1 . A single photon avalanche diode based range detecting apparatus comprising:
a reference array of single photon avalanche diodes configured to receive light from a illumination source via an internally coupled path; a return array of single photon avalanche diodes configured to receive light from the illumination source via an external free space path; a calibration pulse generator configured to generate a calibration signal pulse; and readout circuitry configured to receive:
an output of the reference array via a reference signal path;
an output of the return array via a return signal path; and
an output of the calibration pulse generator via a calibration signal path, the calibration signal path comprising a first signal path substantially following the reference signal path, wherein the readout circuitry is configured to determine a delay difference value between the reference signal path and the return signal path based on the output of the calibration pulse generator via the calibration signal path.

2 . The apparatus as claimed in claim 1 , wherein the first signal path is arranged from the calibration pulse generator to the readout circuitry via the reference array, wherein the calibration signal path further comprises a second signal path coupled to the readout circuitry, and wherein the readout circuitry configured to determine the delay difference value is further configured to:
receive the calibration signal pulse via the first signal path; receive the calibration signal pulse via the second signal path; determine a timing difference between the calibration signal pulses received via the first and the second signal path; and determine the delay difference value as a half of the timing difference.

3 . The apparatus as claimed in claim 1 , wherein the calibration pulse generator is configured to generate a modulated delayed signal that has a dynamic range greater than a quantization step of the readout circuitry.

4 . The apparatus as claimed in claim 1 , wherein the readout circuitry is configured to compensate for any difference between the reference signal path and the return signal path by applying the delay difference value.

5 . The apparatus as claimed in claim 4 , wherein the readout circuitry is configured to compensate for any difference between the reference signal path and the return signal path by delaying the output of the return array by the delay difference value.

6 . The apparatus as claimed in claim 1 , wherein the reference array of single photon avalanche diodes, the return array of single photon avalanche diodes, and the readout circuitry are arranged such that a combination of reference signal path routing area and return signal path routing area is optimized.

7 . The apparatus as claimed in claim 1 , wherein the reference array of single photon avalanche diodes, the return array of single photon avalanche diodes, and the readout circuitry are arranged such that utilization of the area of the apparatus is optimized.

8 . The apparatus as claimed in claim 1 , wherein the illumination source comprises a vertical cavity surface emitting laser or a light emitting diode.

9 . A method for operating a single photon avalanche diode based range detecting apparatus, the method comprising:
receiving light from a illumination source at a reference array of single photon avalanche diodes via an internally coupled path; receiving light from the illumination source at a return array of single photon avalanche diodes via an external free space path; generating a calibration signal pulse; receiving an output of the reference array via a reference signal path; receiving an output of the return array via a return signal path; receiving the generated signal pulse via a calibration signal path, the calibration signal path comprising a first signal path substantially following the reference signal path; and determining a delay difference value between the reference signal path and the return signal path based receipt of the generated signal pulse via the calibration signal path.

10 . The method as claimed in claim 9 , wherein the output of the reference array, the output of the return array, and the generated signal pulse are received at readout circuitry.

11 . The method as claimed in claim 10 , wherein the calibration signal pulse is generated by a calibration pulse generator.

12 . The method as claimed in claim 11 , wherein the first signal path is arranged from the calibration pulse generator to the readout circuitry via the reference array; and
wherein a second signal path for the calibration signal path is coupled to the readout circuitry; wherein determining the delay difference value further comprises:
receiving the calibration signal pulse via the first signal path;
receiving the calibration signal pulse via the second signal path;
determining a timing difference between the calibration signal pulses received via the first and the second signal path; and
determining the delay difference value as a half of the timing difference.

13 . The method as claimed in claim 10 , further comprising generating a modulated delayed signal that has a dynamic range greater than a quantization step of the readout circuitry.

14 . The method as claimed in claim 10 , wherein the reference array of single photon avalanche diodes, the return array of single photon avalanche diodes, and the readout circuitry are arranged such that a combination of reference signal path routing area and return signal path routing area is optimized.

15 . The method as claimed in claim 10 , wherein the reference array of single photon avalanche diodes, the return array of single photon avalanche diodes, and the readout circuitry are arranged such that utilization of the area of the apparatus is optimized.

16 . The method as claimed in claim 9 , further comprising applying the delay difference value to compensate for any difference between the reference signal path and the return signal path.

17 . The method as claimed in claim 16 , wherein applying the delay difference value to compensate for any difference between the reference signal path and the return signal path comprises delaying the output of the return array by the delay difference value.

18 . A single photon avalanche diode based range detecting apparatus comprising:
a reference array of single photon avalanche diodes configured to receive light from a illumination source via an internally coupled path; a return array of single photon avalanche diodes configured to receive light from the illumination source via an external free space path; a calibration pulse generator configured to generate a calibration signal pulse; readout circuitry configured to determine a delay difference value based on signals from the reference array and the return array; a reference signal path coupled between the reference array and the readout circuitry; a return signal path coupled between the return array and the readout circuitry; and a calibration signal path coupled between the calibration pulse generator the readout circuitry, the calibration signal path comprising a first signal path substantially following the reference signal path.

19 . The apparatus as claimed in claim 18 , wherein the first signal path is arranged from the calibration pulse generator to the readout circuitry via the reference array, wherein the calibration signal path further comprises a second signal path coupled to the readout circuitry.

Assignees

• St Microelectronics Res & Dev Ltd

Inventors

• Moore John Kevin
• Zhuang Caixin

Classifications

• G01S17/894

  Three-dimensional [3D] imaging with simultaneous measurement of time-of-flight at a two-dimensional [2D] array of receiver pixels, e.g. time-of-flight cameras or flash lidar · CPC title

• G01D5/26 Primary

  characterised by optical transfer means, i.e. using infrared, visible, or ultraviolet light · CPC title

• G01S7/497

  Means for monitoring or calibrating · CPC title

• G09G3/3216

  using a passive matrix · CPC title

• G01S7/4863

  Detector arrays, e.g. charge-transfer gates · CPC title