Imaging device and method for processing image data of a large area array

• US 8,416,331 B2
• Filed: 12/09/2008
• Issued: 04/09/2013
• Est. Priority Date: 11/19/2007
• Status: Active Grant

• Current Assignee: Leonardo S.p.A.
• Original Assignee: Selex Galileo Limited (Leonardo S.p.A.)
• Inventors: Thorne, Peter Michael
• Primary Examiner(s): KHAN, USMAN A
• Application Number:
  US12/742,877
• Publication Number:
  US 20100289934A1
• Time in Patent Office: 1,582 Days
• Field of Search: 348/302
• US Class Current: 348/302
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• CPC Class Codes: H04N 25/40 Extracting pixel data from image sensors by controlling scanning circuits, e.g. by modifying the number of pixels sampled or to be sampled
• CPC Class Codes: H04N 25/42 by switching between different modes of operation using different resolutions or aspect ratios, e.g. switching between interlaced and non-interlaced mode
• CPC Class Codes: H04N 25/44 by partially reading an SSIS array
• CPC Class Codes: H04N 25/46 by combining or binning pixels
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components

Abstract

An imaging device is capable of on-chip processing data output by a series of pixels 1, 2, 16. The pixels 1, 2, 16 are arranged into a series of super pixels or tiles that together form a large area array. The pixels 1, 2, 16 are arranged into two groups, nominally group A (odd pixels) and group B (even pixels). Data from the individual pixels 1, 2, 16 is read out according to the relative position of the pixel within each group. The technique employed by the device allows the array data rate to be controlled dynamically by the super pixel information content. The output data bandwidth is increased at the expense of image spatial resolution where scene content contains large uniform areas (e.g. desert, sea, sky) that would otherwise generate huge amounts of similar data that carries little additional information.

Claims

1. An imaging device for producing an image of a scene, comprising:

a series of tiles, said tiles comprising a series of pixels arranged into at least two groups by interconnecting switches, allowing signal information at pixel level to be shared using sample and hold and charge sharing circuits; and

a comparator to provide in pixel signal processing within each tile and independently of all other tiles, such that the imaging device data rate is controlled dynamically by tile information content,

wherein the comparator comprises a series of sample and hold circuits for sampling and holding consecutive frames of data, the sample and hold circuits including a comparator and being operated to re-readout data allowing a tile readout to be followed with pixel level readout at the expense of a small reduction in signal voltage.

2. The imaging device according to claim 1, in which output data bandwidth is increased at the expense of image spatial resolution where scene content contains large uniform areas.

3. The imaging device according to claim 1, in which pixel or tile operation is capable in one of two modes, a first mode where operation at low frame rates is allowed to attain image detail or a second mode where operation at high frame rates is allowed with reduced detail.

4. The imaging device according to claim 3, in which the modes may be interleaved for arbitrary durations to provide high bandwidth or high resolution information at different rates.

5. The imaging device according to claim 1, in which a readout may be combined with windowing to provide high resolution readout of regions of interest.

6. The imaging device according to claim 1, in which re-readout of the data in conjunction with sample windowing enables selected areas of interest to be read out repeatedly but at higher resolutions.

7. The imaging device according to claim 1, in which the sample and hold circuits further comprise:

sample and hold capacitors, the capacitors being operated so as to store the previous frame of data by disabling capacitor reset such that the comparator output signal can be used to identify changes in the scene.

8. The imaging device according to claim 7, in which the sample and hold circuit is operated to charge share integrated scene image data continuously frame by frame, the pixel readout being compared to the scene average allowing the device to detect differences between current and historical scene content.

9. A method of capturing an image, comprising:

arranging a series of pixels, contained within a series of tiles, into at least two groups by interconnecting switches to share signal information at a pixel level using sample and hold circuits; and

processing pixel signals within each tile independently of other tiles to dynamically control imaging device data by tile information content by sampling and holding consecutive frames of data, wherein data is re-readout allowing a tile readout to be followed with pixel level readout at the expense of a small reduction in signal voltage.