Sensing module for accelerating signal readout from image sensors

• US 6,172,352 B1
• Filed: 09/27/1999
• Issued: 01/09/2001
• Est. Priority Date: 03/20/1998
• Status: Expired due to Term

• Current Assignee: Ambir Technology Incorporated
• Original Assignee: Syscan Incorporated (Document Capture Technologies, Inc.)
• Inventors: Liu, Dongtai
• Primary Examiner(s): Allen, Stephone B.
• Application Number:
  US09/405,942
• Time in Patent Office: 470 Days
• Field of Search: 250/208.1, 348/249, 348/280, 348/303, 348/311, 348/312, 348/322, 348/317, 358/500
• US Class Current: 250/208.1
• 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

Abstract

The present invention has been made in consideration of accommodating a higher sensor clock signal to increase the pixel readout rate from a regular image sensor and has particular applications to generating high-resolution and high-speed images from scanning objects. The sensing module in the present invention uses a number of readout passages in parallel to produce several segmented outputs from the image sensor and subsequently combine the outputs to produce an interleaved scanning signal under a sequence of control signals derived from a sensor clock signal.

Claims

1. A method for accelerating signal readout from an image sensor including N photodetectors producing N charging signals when exposed to a scene, the method comprising:

dividing the N photodetectors into M groups so that each of the M groups includes K charging signals, wherein K=N/M;

reading out in parallel one of the K charging signals in each of the M groups at a time;

continuing to read out a next one of the K charging signals in each of the M groups at a time till all of the K charging signals in each of the M groups are readout; and

reordering the readout N charging signals in a predefined order.

2. The method of claim 1, wherein the N charging signals produced from the image sensor is in the predefined order.

3. The method of claim 2, wherein the predefined order is a sequential order.

4. The method of claim 1, wherein the readout charging signals are stored in a memory space having N memory cells, each holding one of the readout N charging signals.

5. The method of claim 4, wherein the ordering of the readout charging signals in a predefined order is performed by selectively reading out the charging signals stored in the N memory cells.

6. A method for accelerating signal readout from an image sensor including N photodetectors producing N charging signals when exposed to a scene, the method comprising:

reading out K of the N charging signals at a time, wherein K=N/M and M is a number of groups dividing the N charging signals and wherein the adjacent two of the K charging signals do not correspond to adjacent two of the N charging signals;

continuing to read out another set of K signals from the N charging signals till all of the N charging signals are readout; and

reordering the readout N charging signals in a predefined order.

7. The method of claim 6, wherein the N charging signals produced from the image sensor is in the predefined order.

8. The method of claim 7, wherein the predefined order is a sequential order.

9. A sensing module for accelerating signal readout from an image sensor, the sensing module comprising:

an array of N photodetectors producing N scanning signals when exposed to a scanning object;

a timing circuit, in response to a clock signal having a clock cycle T, producing M control signals, wherein the M control signals are respectively delayed by the clock cycle T;

M readout passages, coupled to the array of N photodetectors and receiving the N scanning signals therefrom, each of the M readout passages respectively and independently controlled by one of the M control signals and reading out one of the N scanning signals from the array of N photodetectors so that each time M of the N scanning signals are readout;

a multiplexer having M inputs respectively receiving the M scanning signals and the multiplexer, in response to the M control signals, successively sampling the N scanning signals to subsequently produce N interleaved scanning signals.

10. The sensing module as recited in claim 9 further comprising an ordering processor for reordering the N interleaved scanning signals to an order the N scanning signals are presented.

11. The sensing module as recited in claim 9, wherein each of the readout passages comprises a switch array and a local video bus, wherein the switch array comprises K readout switches, each of the readout switches coupled to the local video bus, and wherein K=N/M and each of the readout switches in each of the switch arrays is respectively coupled to one of the photodetectors.

12. The sensing module as recited in claim 11, wherein each of the readout passages produces, respectively, each of the M scanning signals by turning on sequentially the readout switches therein.

13. The sensing module as recited in claim 11, wherein each of the readout passages comprises a shift register comprising a plurality of memory cells, each of the memory cells receiving respectively one of the M scanning signals.

14. The sensing module as recited in claim 13, wherein each of the shift registers shifts out serially the one of the M scanning signals in each of the memory cells out, in response to one of the M control signals, to produce respectively one of the N Interleaved scanning signals.