Fast gating photosurface

• US 8,717,469 B2
• Filed: 02/03/2010
• Issued: 05/06/2014
• Est. Priority Date: 02/03/2010
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Felzenshtein, Shlomo, Yahav, Giora, Larry, Eli
• Primary Examiner(s): Haskins, Twyler
• Assistant Examiner(s): Chon, Peter
• Application Number:
  US12/699,074
• Publication Number:
  US 20110187826A1
• Time in Patent Office: 1,553 Days
• Field of Search: 348/135, 348/207.99, 348/345, 348/348, 348/272, 348/281, 348/282, 348/283, 348/294, 348/295, 348/296, 348/297, 348/298, 348/299, 348/303, 348/304, 348/307, 348/308, 348/309, 348/310, 348/311, 348/312, 348/313, 348/314, 348/316, 348/317, 348/319, 348/320, 348/321, 348/322, 348/323, 348/349
• US Class Current: 348/294
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G01S 7/4863 Detector arrays, e.g. charge-transfer gates
• CPC Class Codes: H01L 27/146 Imager structures
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/148 Charge coupled imagers individual charge coupled devices H01L29/765
• CPC Class Codes: H04N 13/20 Image signal generators
• CPC Class Codes: H04N 13/204 using stereoscopic image cameras stereoscopic photography G03B35/00
• CPC Class Codes: H04N 13/254 in combination with electromagnetic radiation sources for illuminating objects
• CPC Class Codes: H04N 13/296 Synchronisation thereof; Control thereof
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• CPC Class Codes: H04N 25/50 Control of the SSIS exposure

Abstract

An embodiment of the invention provides a camera comprising a photosurface that is electronically turned on and off to respectively initiate and terminate an exposure period of the camera at a frequency sufficiently high so that the camera can be used to determine distances to a scene that it images without use of an external fast shutter. In an embodiment, the photosurface comprises pixels formed on a substrate and the photosurface is turned on and turned off by controlling voltage to the substrate. In an embodiment, the substrate pixels comprise light sensitive pixels, also referred to as “photopixels”, in which light incident on the photosurface generates photocharge, and storage pixels that are insensitive to light that generates photocharge in the photopixels. In an embodiment, the photosurface is controlled so that the storage pixels accumulate and store photocharge substantially upon its generation during an exposure period of the photosurface.

Claims

1. A method of gating a photosurface comprising a substrate on which photopixels and associated storage pixels are formed, the method comprising:

applying a first voltage at a first time to the substrate to turn on the photosurface and initiate an exposure period of the photosurface;

applying a second voltage at a second time to the substrate to turn off the photosurface and end the exposure period; and

biasing the photopixels and associated storage pixels to maintain a photocharge transfer state substantially at all times between the first and second times in which photocharge moves substantially upon its generation by light incident on a photopixel between the first and second times towards the photopixel'"'"'s storage pixel.

2. A method according to claim 1 wherein a time lapse between the first and second times is less than 100 ns.

3. A method according to claim 2 wherein the time lapse between the first and second times is less than 35 ns.

4. A method according to claim 3 wherein the time lapse between the first and second times is less than 20 ns.

5. A method according to claim 1 and acquiring a frame of the photosurface following the second time.

6. A method according to claim 1 and repeatedly turning on and turning off the photosurface to provide a plurality of exposure periods.

7. A method according to claim 6 and repeatedly turning on and turning off the photosurface at a repetition frequency greater than or equal to 2.5 MHz.

8. A method according to claim 7 wherein the repetition frequency is greater than or equal to 5 MHz.

9. A method according to claim 8 wherein the repetition frequency is greater than or equal to 10 MHz.

10. A method according to claim 9 and acquiring a frame of the photosurface for the plurality of exposure periods only following the second time of a last exposure period of the plurality of exposure periods.

11. A method for determining distances to features in a scene, the method comprising:

illuminating the scene with a train of light pulses;

gating a photosurface having a substrate on which photopixels and associated storage pixels are formed in accordance with claim 1 to register light reflected by the features from the light pulses; and

using the registered light to determine distances to the features.

12. A method in accordance with claim 11 wherein gating comprises gating for each light pulse in the pulse train responsive to a time at which the light pulse is transmitted.

13. A method according to claim 1 wherein the photosurface comprises at least one photosurface chosen from the group consisting of a CCD, a CMOS and an interline photosurface.

14. A camera comprising:

a photosurface having a substrate on which photopixels and associated storage pixels are formed; and

a controller that controls the photosurface in accordance with claim 1 to image a scene.

15. A 3D camera for providing distances to features in a scene, the camera comprising:

a light source that transmits a train of light pulses to illuminate the scene;

a photosurface having photopixels that receive light reflected by the features from the light pulses; and

a controller that gates on and gates off the photosurface in accordance with claim 1 for each light pulse in the pulse train responsive to a time at which the light pulse is transmitted.

16. A camera according to claim 14 wherein the photosurface comprises at least one photosurface chosen from the group consisting of a CCD, CMOS and interline photosurface.

17. A method according to claim 6 wherein biasing the photopixels and associated storage pixels is maintained substantially the same as the biasing during the plurality of exposure periods for periods between the plurality of exposure periods.