Neighborhood-gated switching pixel sensor
The present invention relates to an imaging sensor system ( 26 ) having a high detection accuracy. The system ( 26 ) comprises a plurality of pixel sensors ( 1 ) and at least one light source. The pixel sensors ( 1 ) are grouped in clusters, wherein each pixel sensor ( 1 ) comprises a photodetector ( 2 ) and a local controlling circuit ( 18 ). The plurality of sensors ( 1 ) in each cluster are configured, using local controlling circuits ( 18 ), to output a global detection signal ( 15 ) when detecting a local detection signal ( 10 ) from at least two outputs of the photodetectors ( 2 ) of said cluster. The system ( 26 ) has a high detection accuracy due to ruling out false positive detections, since each detection requires at least two positive outputs of the photodetectors ( 2 ) of said cluster.
1. An imaging sensor system, comprising:
a plurality of pixel sensors, wherein the pixel sensors are grouped in at least one local cluster comprising at least two pixel sensors, wherein each pixel sensor of the at least one local cluster adjoins at least one other pixel sensor of the at least one local cluster,
wherein each pixel sensor comprises:
a photodetector capable of detecting single photons impinging thereon, the photodetector having an output for outputting an electrical local detection signal upon detection of a photon;
a local controlling circuit, wherein the plurality of pixel sensors in the at least one local cluster are configured, using the local controlling circuit, to output a global detection signal when detecting a local detection signal from at least two outputs of the photodetectors of the at least one local cluster; and
at least one light source;
wherein the local controlling circuit of each pixel sensor comprises: a local enabling circuit, and a neighborhood enabling circuit connected to the local enabling circuit,
wherein the local detection signal of the pixel sensor is provided to the local enabling circuit in the pixel sensor,
wherein the neighborhood enabling circuit of the pixel sensor is provided with at least one local detection signal of at least one other pixel sensor in the at least one local cluster,
wherein the pixel sensors are configured to output the global detection signal when both the local enabling circuit and the neighborhood enabling circuit are triggered
wherein the plurality of pixel sensors in the at least one local cluster are configured to output the global detection signal when detecting a local detection signal from at least two outputs of the photodetectors of the local cluster within a predetermined time delay.
2. The imaging sensor system of claim 1 , wherein the photodetector is a single-photon detector or a single-photon avalanche diode.
3. The imaging sensor system of claim 1 , wherein the local enabling circuit or the neighborhood enabling circuit comprise transistors.
4. The imaging sensor of claim 3 , wherein the transistors are NMOS transistors.
5. The imaging sensor of claim 3 , wherein current flows through the transistor of the local enabling circuit and the transistor of the neighborhood enabling circuit when both transistors are switched on.
6. The imaging sensor of claim 3 , wherein the local detection signal is provided to gates of the transistors.
7. The imaging sensor of claim 3 , wherein the transistors comprise a transistor coupled to the at least one row bus and a transistor coupled to the at least one column bus.
8. The imaging sensor system of claim 1 , wherein at least one pixel sensor further comprises a buffer connected to the photodetector output of the at least one pixel sensor, wherein the buffer compares the photodetector output to a predetermined threshold voltage level.
9. The imaging sensor of claim 8 wherein an output of the buffer is the local detection signal.
10. The imaging sensor system of claim 1 , wherein the global detection signals of different clusters are aggregated with one another to form a cluster detection signal.
11. The imaging sensor of claim 10 , wherein the cluster detection signal is a binary signal.
12. The imaging sensor system of claim 1 , wherein the local detection signals and/or the global detection signals are binary signals.
13. The imaging sensor system of claim 1 , wherein at least two pixel sensors are associated with more than one cluster.
14. The imaging sensor of claim 13 , wherein the local detection signals of the at least two pixel sensors are provided to neighborhood enabling circuits associated with different clusters.
15. The imaging sensor system according to claim 1 , wherein the system comprises a maximum of hundred pixel sensors or a maximum of fifty pixel sensors connected in one row or in one column.
16. The imaging sensor of claim 1 , wherein the local enabling circuit and the neighborhood enabling circuit are connected in series.
17. The imaging sensor of claim 1 , wherein the plurality of pixel sensors is located on a first semiconductor layer, and the local controlling circuit of each pixel sensor is located on a second semiconductor layer.
18. The imaging sensor of claim 1 , wherein the global detection signals in each row are aggregated with one another to form a row detection signal, and wherein the global detection signals in each column are aggregated with one another to form a column detection signal.
19. The imaging sensor system according to claim 18 , further comprising a synchronization circuit for synchronizing the row and the column detection signals.