High speed digital framing camera

• US 5,387,926 A
• Filed: 06/30/1992
• Issued: 02/07/1995
• Est. Priority Date: 06/30/1992
• Status: Expired due to Fees

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Bellan, Paul M.
• Primary Examiner(s): Mancuso, Joseph
• Assistant Examiner(s): GARBER, WENDY RAE
• Application Number:
  US07/906,898
• Time in Patent Office: 952 Days
• Field of Search: 358/209, 358/206, 358/332, 358/108, 358/105, 358/213.11, 358/199, 348/61, 348/203, 348/231
• US Class Current: 348/61
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• CPC Class Codes: H04N 3/09 for electromagnetic radiation in the invisible region, e.g. infrared

Abstract

The present invention provides a system for recording images occurring both before and after a triggering event. Temporarily stored images are continually refreshed, the most recent images replacing the oldest images, providing a continuously updated history of recent events in a memory configured as an endless loop. Upon receipt of an external trigger, a predetermined further quantity of temporary images are stored until the capacity of the temporary storage medium is reached and then all temporarily stored images are then permanently stored. The system includes a rotating polygon mirror which produces a sequence of image scan lines. A lens system focuses the scan lines onto a linear array of photodetectors. Transient digitizers or a CCD linear storage array temporarily stores image data received from the photodetectors. Upon receipt of a trigger, the temporarily stored images are transferred to permanent digital memory after a predetermined further quantity of images have been stored.

Claims

1. A digital framing camera comprising:

means for scanning an image in a horizontal direction;

a single linear array of photodetectors for receiving said image by receiving a series or vertical segments of said image in sequence, each of said vertical segments being a different portion of the image scanned by the scanning means;

storage means having a fixed capacity for temporarily storing a first quantity of the vertical segments;

first means responsive to a trigger signal for temporarily storing a predetermined further second quantity of the vertical segments into the storage means; and

second means responsive to the trigger signal for permanently storing the first and second quantities of vertical segments stored in the storage means.

2. The digital framing camera of claim 1 wherein the second means further comprises:

third means for permanently storing the first and second quantities of vertical segments after the second quantity of vertical segments have been stored in response to the trigger signal.

3. The digital framing camera of claim 1 wherein the scanning means comprises a rotating polygon mirror.

4. The digital framing camera of claim 1 wherein the receiving means comprises:

a lens system which focuses output from the scanning means onto an image plane; and

a linear array of photodetectors placed in the image plane.

5. The digital framing camera of claim 4 wherein the storage means further comprises a transient digitizer in communication with each photodetector.

6. The digital framing camera of claim 4 wherein the storage means comprises a CCD linear storage array in communication with the linear array of photodetectors.

7. The digital framing camera of claim 1 wherein the storage means further comprises:

a fixed capacity memory organized in an endless loop fashion.

8. The digital framing camera of claim 1 wherein the second means comprises digital memory and associated control circuitry.

9. The digital framing camera of claim 1 wherein the second means comprises a computer.

10. An optoelectronic scanning system for recording images, comprising:

a scanning optical element driven in rotation for scanning an image in a horizontal direction;

a focusing optical element for focusing linear vertical segments of the image scanned by the scanning optical element, each of said vertical segments being a different portion of said image sequentially scanned by the scanning optical element;

a detection system having a linear array of optical detectors for detecting segments focused by the focusing optical element;

a digital system in communication with the detection system for temporarily storing a first quantity of said segments, said digital system further responsive to a trigger signal for temporarily storing a predetermined second quantity of segments so that said digital system includes the first quantity stored before said trigger signal as well as the second quantity stored thereafter.

11. The system of claim 10, wherein the digital system further comprises:

means for permanently storing the first and second quantities of vertical segments.

12. The system of claim 10 wherein the optical element driven in rotation comprises a rotating polygon mirror.

13. The system of claim 10 wherein the optical element for focusing the vertical segments comprises a lens system which focuses the vertical segments into an image plane.

14. The system of claim 10 wherein the detection system comprises a linear array of photodetectors placed in the image plane.

15. The system of claim 10 wherein the digital system comprises a transient digitizer in communication with each optical detector in the linear array of optical detectors.

16. The system of claim 10 wherein the digital system comprises a CCD linear storage array in communication with the linear optical detectors.

17. The system of claim 11 wherein the means for permanently storing the vertical segments further comprises a digital memory array and associated control circuitry.

18. A method of detecting and storing random high speed events, comprising the steps of:

scanning an image;

detecting lines of the image sequentially by a single linear array of photodetectors, each line being a different portion of the image scanned in the scanning step;

temporarily storing a quantity of the detected lines;

detecting a trigger signal for temporarily storing a predetermined further quantity of the detected lines; and

then

permanently storing the quantity of temporarily stored detected lines.

19. The method of claim 18 wherein the scanning step comprises the steps of:

reflecting the images with a rotating polygon mirror; and

focussing reflection from the mirror onto an image plane.

20. The method of claim 19 wherein the step of detecting the scan lines further comprises the step of:

detecting the scan lines with a linear array of photodetectors placed in the image plane.