Imaging system

• US 20050036655A1
• Filed: 08/13/2004
• Published: 02/17/2005
• Est. Priority Date: 08/13/2003
• Status: Active Grant

• Current Assignee: Jonathan D. Lettvin
• Original Assignee: Jonathan D. Lettvin
• Inventors: Lettvin, Jonathan D.
• Granted Patent: US 7,796,173 B2
• Time in Patent Office: Days
• US Class Current: 382/100
• CPC Class Codes: G01S 3/784 using a mosaic of detectors

Abstract

Signals from an object in a field of view are detected by an array of directional sensors and “re-converged” to create a three-dimensional image as the object changes contrast or moves relative to the sensors. Each sensor is oriented along an axis toward the field of view. Sensor signals are converted to logarithms thereof and transients are detected and compared to background signals. Resulting signals are connected in overlapping groups to coincidence detectors in a matrix. Each point in the field of view where two or more sensor axes intersect is represented by a coincidence detector, which is connected to the corresponding group of sensors. If a threshold number of sensors in the group detects a transient, the corresponding point in the image is deemed to be “contrasty” and can be made visible or otherwise perceivable by a human or can be further processed by a computer or other circuit.

Claims

1. A device for generating an image of points in a field of view, comprising:

a plurality of directional signal sensors; and

a plurality of coincidence detectors, each coincidence detector being connected to receive a signal from each directional signal sensor of a respective group of the directional signal sensors.

2. The device of claim 1, wherein each coincidence detector is configured to produce an output signal upon detecting coincidental signals from at least some of the directional signal sensors of the group.

3. The device of claim 2, wherein the coincidence detector is configured to produce the output signal upon detecting the coincidental signals within a predetermined time.

4. The device of claim 2, wherein the output signal indicates a degree of coincidence among the coincidental signals from the directional signal sensors of the group.

5. The device of claim 2, wherein the output signal does not indicate a degree of coincidence among the coincidental signals from the directional signal sensors of the group.

6. The device of claim 1, wherein each coincidence detector is configured to produce an output signal upon detecting coincidental signals from at least a predetermined number of the directional signal sensors of the group.

7. The device of claim 6, wherein the coincidence detector is configured to produce the output signal upon detecting the coincidental signals within a predetermined time.

8. The device of claim 1, wherein the directional signal sensors of the group lie along at least a portion of a circle.

9. The device of claim 1, wherein the directional signal sensors of the group are oriented toward a common point in the field of view.

10. The device of claim 9 wherein the directional sensors of the group lie along at least a portion of a circle.

11. The device of claim 1, further comprising a plurality of comparators, each comparator being connected between at least one of the directional signal sensors and at least one of the coincidence detectors to provide a signal indicative of a difference between a flux transient detected by the directional signal sensor and a background flux transient.

12. The device of claim 11, further comprising a plurality of background signal sensors, wherein each comparator is connected to at least one of the background signal sensors to receive a signal indicative of the background flux.

13. The device of claim 11, wherein each comparator is also connected to a respective subset of the plurality of directional sensors to obtain a signal indicative of the background flux.

14. The device of claim 1, further comprising a transient detector along a signal path from each of the directional signal sensors to a respective coincidence detector.

15. The device of claim 14, wherein the transient detector is configured to detect up transients and down transients.

16. The device of claim 1, further comprising a logarithmic converter along a signal path from each of the directional signal sensors to a respective coincidence detector.

17. The device of claim 1, further comprising a plurality of visible display elements, each visible display element being connected to one of the plurality of coincidence detectors and configured to provide a visible display when the coincidence detector detects coincidental signals from at least two directional signal sensors of the group.

18. The device of claim 17, wherein each visible display element comprises a light emitting diode.

19. The device of claim 17, wherein each visible display element comprises a liquid crystal display element.

20. The device of claim 17, wherein each visible display element is configured to indicate up transients in the coincidental signals differently than the visible display element indicates down transients in the coincidental signals.

21. The device of claim 17, wherein each visible display element indicates a degree of coincidence among the coincidental signals.

22. The device of claim 2, 3, 6 or 7, further comprising a plurality of visible display elements, each visible display element being configured to provide a visible display in response to the production an output signal by at least one of the plurality of coincidence detectors.

23. The device of claim 22, wherein each visible display element comprises a light emitting diode.

24. The device of claim 1, wherein the plurality of directional sensors is distributed across a two-dimensional surface.

25. The device of claim 1, wherein the plurality of directional sensors is distributed across a three-dimensional surface.

26. The device of claim 25, wherein the three-dimensional surface comprises at least a portion of a geodesic dome.

27. The device of claim 25, wherein the three-dimensional surface comprises a piecewise planar surface.

28. The device of claim 25, wherein the three-dimensional surface comprises at least a portion of a sphere.

29. The device of claim 25, wherein the three-dimensional surface comprises a smooth surface.

30. The device of claim 25, wherein the three-dimensional surface comprises at least a portion of a planet.

31. The device of claim 25, wherein the three-dimensional surface comprises at least a portion of a natural satellite.

32. The device of claim 25, wherein the three-dimensional surface comprises at least a portion of an artificial satellite.

33. The device of claim 1, wherein the plurality of sensors is distributed across a plurality of discontiguous surfaces.

34. A device for generating an image of points in a field of view, comprising:

a plurality of directional signal sensors,

a plurality of logarithmic converters, each of the plurality of directional signal sensors being connected to a corresponding one of the plurality of logarithmic converters;

a plurality of transient detectors, each of the plurality of logarithmic converters being connected to a corresponding one of the transient detectors;

a plurality of comparators, each comparator being connected to compare a signal from a corresponding one of the plurality of transient detectors and a signal indicative of a background flux transient to provide a difference signal corresponding to the respective one of the directional signal sensors; and

a plurality of coincidence detectors, each coincidence detector being associated with a group of the plurality of directional signal sensors, each coincidence detector being connected to receive the difference signals corresponding to the associated group of directional signal sensors.

35. The device of claim 34, wherein the group of the plurality of directional signal sensors contains at least one directional signal sensor of another group of directional signal sensors.

36. A logarithmic converter for producing an output signal proportional to a logarithm of an input signal, comprising:

a field effect transistor having a source and a drain defining a source-drain path therethrough and a gate;

an input port connected to the gate of the field effect transistor for receiving the input signal;

a first diode connected in series with the source-drain path of the field effect transistor;

a second transistor having an emitter and a collector defining an emitter-collector path therethrough and a base, the base being connected to a junction between the first diode and the field effect transistor;

a second diode connected in series with the emitter-collector path of the second transistor; and

an output port connected to a junction between the second diode and the emitter-collector path of second transistor.

37. A logarithmic converter for producing an output signal proportional to a logarithm of an input signal, comprising:

a first transistor having a current path therethrough and a high-impedance first control port, resistance of the current path being controlled by at least one of a voltage, a current and a charge applied to the first control port;

an input port connected to the first control port of the first transistor for receiving the input signal;

a first diode connected in series with the current path of the first transistor;

a second transistor having a current path therethrough and a second control port, the second control port being connected to a junction between the first diode and the first transistor;

a second diode connected in series with the current path of the second transistor; and

an output port connected to a junction between the second diode and the current path of second transistor.

38. A comparator for producing a difference signal that represents a difference between a first input signal and a second input signal, comprising:

a first current mirror having an input port for connection to the first input signal and a PNP transistor driving an output port; and

a second current mirror having an input port for connection to the second input signal and an NPN transistor driving an output port;

wherein the output port of the first current mirror is connected to the output port of the second current mirror to provide the difference signal.

39. The comparator of claim 38, further comprising:

a first logarithmic converter interposed between the first current mirror and the first input signal, the first logarithmic converter having;

an input port for connection to the first input signal; and

an output port connected to the input port of the first current mirror; and

a second logarithmic converter interposed between the second current mirror and the second input signal, the second logarithmic converter having;

an input port for connection to the second input signal; and

an output port connected to the input port of the second current mirror.

40. The comparator circuit of claim 39, wherein the first and second logarithmic converters each comprise:

a field effect transistor having a source and a drain defining a source-drain path therethrough and a gate, wherein the input port of the respective logarithmic converter is connected to the gate of the field effect transistor;

a first diode connected in series with the source-drain path of the field effect transistor;

a second transistor having an emitter and a collector defining an emitter-collector path therethrough and a base, the base being connected to a junction between the first diode and the field effect transistor; and

a second diode connected in series with the emitter-collector path of the second transistor;

wherein the output port of the respective logarithmic converter is connected to a junction between the second diode and the emitter-collector path of second transistor.

41. The comparator circuit of claim 39, wherein the first and second logarithmic converters each comprise:

a first transistor having a current path therethrough and a high-impedance control port, resistance of the current path being controlled by at least one of a voltage, a current and a charge applied to the first control port, wherein the input port of the respective logarithmic converter is connected to the first control port of the first transistor;

a first diode connected in series with the current path through the first transistor;

a second transistor having a current path therethrough and a second control port, the second control port being connected to a junction between the first diode and the first transistor; and

a second diode connected in series with the current path of the second transistor;

wherein the output port of the respective logarithmic converter is connected to a junction between the second diode and the current path of second transistor.

42. A coincidence detector, comprising:

a first line comprising a plurality of first, second, third and fifth materials; and

a second line comprising a plurality of first, second, fourth and sixth materials and oriented such that a portion of the second line is proximate a portion of the first line;

wherein;

when excited, the third material radiates a third-type signal that excites the third material;

when excited, the fourth material radiates a fourth-type signal that excites the fourth material;

when excited, the fifth material radiates a fifth-type signal that excites the fifth material;

when excited, the sixth material radiates a sixth-type signal that excites the sixth material;

when excited by a coincidence of the third-type and fourth-type signals, the first material radiates a visible light in a first color;

when excited by a coincidence of the fifth-type and sixth-type signals, the second material radiates a visible light in a second color;

whereby, if the first line is excited by the third-type signal and the second line is coincidentally excited by the fourth-type signal, or the first line is excited by the fifth-type signal and the second line is coincidentally excited by the sixth-type signal, the coincidence detector produces visible light of the first or second color, respectively, in a region where the first line is proximate the second line.

43. The coincidence detector of claim 42, wherein the first, second, third, fourth, fifth and sixth materials each comprise a plurality of nanodots.

44. The coincidence detector of claim 42, wherein the coincidence of the third-type and fourth-type signals comprises an occurrence of the third-type signal within a predetermined time of an occurrence of the fourth-type signal and the coincidence of the fifth-type and sixth-type signals comprises an occurrence of the fifth-type signal within a predetermined time of an occurrence of the sixth-type signal.

45. A coincidence detector, comprising:

a first line comprising a plurality of first and second materials; and

a second line comprising a plurality of first and third materials and oriented such that a portion of the second line is proximate a portion of the first line;

wherein;

when excited, the second material radiates a second-type signal that excites the second material;

when excited, the third material radiates a third-type signal that excites the third material;

when excited by a coincidence of the second-type and third-type signals, the first material radiates a visible light;

whereby, if the first line is excited by the second-type signal and the second line is coincidentally excited by the third-type signal, the coincidence detector produces visible light in a region where the first line is proximate the second line.

46. The coincidence detector of claim 45, wherein the first, second and third materials each comprise a plurality of nanodots.

47. The coincidence detector of claim 45, wherein the coincidence of the second-type and third-type signals comprises an occurrence of the second-type signal within a predetermined time of an occurrence of the third-type signal.