Methods and apparatus for charge coupled device image acquisition with independent integration and readout

• US 6,608,647 B1
• Filed: 05/29/1998
• Issued: 08/19/2003
• Est. Priority Date: 06/24/1997
• Status: Expired due to Fees

• Current Assignee: Cognex Corporation
• Original Assignee: Cognex Corporation
• Inventors: King, David R.
• Primary Examiner(s): Vu, Ngoc-Yen, VU, NGOC YEN T
• Application Number:
  US09/087,592
• Time in Patent Office: 1,908 Days
• Field of Search: 348/14.01, 348/14.02, 348/14.08, 348/14.09, 348/207, 348/211-213, 348/222, 348/218, 348/311, 348/312, 348/552, 348/207.1, 348/207.11, 348/211.99, 348/211--21, 348/222.1, 348/218.1, 348/257, 348/317, 257/231, 257/232, 257/236
• US Class Current: 348/211.14
• CPC Class Codes: H04N 23/60 Control of cameras or camera modules
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• CPC Class Codes: H04N 25/70 SSIS architectures; Circuits associated therewith

Abstract

Methods and apparatus for image acquisition utilize a charge coupled device having a photosensitive region that responds to an applied transfer signal by transferring charge accumulated on the collection sites to the corresponding readout sites. The non-photosensitive region responds to a read signal, applied independently of the transfer signal, by outputting (e.g., to the host camera or image acquisition system) charges on the readout sites. The methods and apparatus take advantage of the inherent storage capability of the non-photosensitive sites by using them to hold image information pending application of the readout signal, thereby, conserving host resources.

Claims

1. An image acquisition apparatus comprising:

A. a charge coupled device including a photosensitive region having one or more photosensitive charge collection sites, a non-photosensitive region having one or more non-photosensitive readout sites, the readout sites being coupled any of directly and indirectly to corresponding charge collection sites, the photosensitive region responding to an applied transfer signal for moving charges accumulated on the charge collection sites to corresponding non-photosensitive readout sites, the non-photosensitive region responding to a read signal applied independently of the transfer signal for outputting charges from the readout sites,

B. a head unit, coupled to the charge coupled device, that generates an image signal based on charges output from the readout sites.

2. An image acquisition apparatus according to claim 1, comprising

A. a control unit that responds to requests from a host by generating and applying to the head unit signals for acquiring an image, and

B. the head unit responding to signals applied thereto by the control unit for applying to the charge coupled device (i) the transfer signal for moving charges accumulated on the charge collection sites to corresponding readout sites, and (ii) the read signal causing charges to be output from the readout sites.

3. An image acquisition apparatus according to claim 2, wherein the control unit generates and applies to the head unit at least one of (i) a shutter pulse defining at least a duration of charge integration by the charge coupled device, and (ii) a readout signal that effects output of charges from the readout sites.

4. An image acquisition apparatus according to claim 3, wherein the head unit responds to the shutter pulse for applying to the charge coupled device a reset signal for clearing the charge collection sites and for applying to the charge coupled device the transfer signal for causing charges accumulated on those sites to be transferred to the readout sites so as to effect an integration period having the duration in accord with that defined by the shutter pulse.

5. An image acquisition apparatus according to claim 4, wherein the head unit applies the read signal to the charge coupled device subsequent to application of the transfer signal so as to effect output to the head unit of charges in the readout sites.

6. An image acquisition apparatus according to claim 2, wherein the control unit includes a video path that conditions the image signal received from the head unit.

7. An image acquisition apparatus according to claim 6, wherein the video path includes a gain adjustment element that any of (i) adjusts a gain of the image signal received from the head unit, and (ii) increases an amplitude of that image signal.

8. An image acquisition apparatus according to claim 6, wherein video path includes a level correction element that eliminates residual offsets in the image signal received from the head unit.

9. An image acquisition apparatus according to claim 1, comprising

A. a control unit that responds to a request from a host by generating and applying to the head unit (i) a shutter pulse defining at least a duration of charge integration by the charge coupled device, and (ii) a readout signal that effects output of charges from the readout sites,

B. the head unit responding to the shutter pulse for applying to the charge coupled device a reset signal for clearing the charge collection sites and for applying to the charge coupled device the transfer signal for causing charges accumulated on those sites to be transferred to the readout site,

C. the head unit responding to the readout signal applied thereto by the control unit for applying the read signal to the charge coupled device for effecting output of charges in the readout sites, and

D. the control unit including a video path that conditions the image signal generated by the head unit from charges output from the readout sites.

10. An image acquisition apparatus according to claim 9, wherein the video path includes

i) a gain adjustment element that any of (a) adjusts gain of the image signal received from the head unit, and (b) increases an amplitude of that image signal, and

ii) a level correction element that any of eliminates residual offsets in an image signal received from the head unit.

11. An image acquisition apparatus comprising:

A. a plurality of head units, each including a charge coupled device, and each that generates an image signal from charges output from readout sites of the respective charge coupled device,

B. each charge coupled device including a photosensitive region having one or more photosensitive charge collection sites, a non-photosensitive region having one or more non-photosensitive readout sites, the readout sites being coupled to corresponding charge collection sites, the photosensitive region responding to an applied transfer signal for moving charges accumulated on the charge collection sites to corresponding non-photosensitive readout sites, the non-photosensitive region responding to a read signal applied independently of the transfer signal for outputting the charges from the readout sites, and

C. a control unit, that is coupled to the plurality of head units, selectively generates and applies to each head unit signals for acquiring an image.

12. An image acquisition apparatus according to claim 11, wherein the control unit generates and applies to each head unit at least one of (i) a shutter pulse defining at least a duration of charge integration by the respective charge coupled device, and (ii) a readout signal that effects output of charges from the respective readout sites.

13. An image acquisition apparatus according to claim 12, wherein each head unit responds to the shutter pulse for applying to the respective charge coupled device a reset signal for clearing the charge collection sites and for applying to the respective charge coupled device the transfer signal for causing charges accumulated on those sites to be transferred to the readout sites.

14. An image acquisition apparatus according to claim 13, wherein each head unit applies the transfer signal to the respective charge coupled device subsequent to its application of the reset signal to that charged coupled device so as to effect an integration period having the duration in accord with that defined by the shutter pulse applied by the control unit to that head unit.

15. An image acquisition apparatus according to claim 11, wherein the control unit includes a video path that conditions image signals generated by the head units.

16. An image acquisition apparatus according to claim 15, wherein the video path includes

i) a gain adjustment element that any of (a) adjusts gain of the image signal received from the head units, and (b) increases an amplitude of that image signal, and

ii) a level correction element that any of eliminates residual offsets in the image signal received from the head units.

17. An image acquisition system according to claim 11, wherein the control unit has a synchronous mode of operation wherein it applies a shutter pulse signal substantially concurrently to the plurality of head units, and an asynchronous mode of operation wherein it applies a shutter pulse signal to the plurality of head units at substantially different respective times.

18. An image acquisition system according to claim 17, wherein the control unit applies a readout signal to the plurality of head units at substantially different respective times.

19. An image acquisition system according to any of claims 17-18, wherein the control unit applies the shutter pulse signal and the readout signal to the plurality of head units in accord with one or more requests received from a host.

20. A method of image acquisition using a charge coupled device of the type having

i. a photosensitive region having one or more photosensitive charge collection sites,

ii. a non-photosensitive region having one or more non-photosensitive readout sites, the non-photosensitive readout sites being coupled to corresponding photosensitive charge collection sites,

the method comprising the steps of

A. responding to an applied transfer signal for moving charges accumulated on the charge collection sites to corresponding readout sites, and

B. responding to a read signal applied independently of the transfer signal for outputting the charges in the non-photosensitive readout sites.

21. A method according to claim 20, comprising the step of responding to an applied reset signal for clearing charges on the charge collection sites.

22. A method according to claim 20, comprising the step of utilizing a head unit to generate an image signal based on charges output from the readout sites.

23. A method according to claim 22, comprising the steps of

A. utilizing a control unit to generate and apply to the head unit signals for acquiring an image, and

B. responding, with the head unit, to signals applied thereto by the control unit for applying to the charge coupled device (i) the transfer signal for moving charges accumulated on the charge collection sites to corresponding readout sites, and (ii) the read signal causing charges to be output from the readout sites.

24. A method according to claim 23, comprising the step of utilizing the control unit to generate and apply to the head unit at least one of (i) a shutter pulse defining at least a duration of charge integration by the charge coupled device, and (ii) a readout signal that effects output of charges from the readout sites.

25. A method according to claim 24, comprising the step of responding, with the head unit, to the shutter pulse for applying to the charge coupled device a reset signal for clearing the charge collection sites and for applying to the charge coupled device the transfer signal for causing charges accumulated on those sites to be transferred to the readout sites.

26. A method according to claim 25, comprising the step of utilizing the head unit to apply the transfer signal to the charge coupled device subsequent to application of the reset signal so as to effect an integration period having the duration in accord with that defined by the shutter pulse.

27. A method according to claim 26, comprising the step of utilizing the control unit to condition the image signal generated by the head unit.

28. A method according to claim 20, comprising the step of utilizing a plurality of head units, each coupled to a respective charge coupled device to generate an image signal based on charges output from readout sites thereof.

29. A method according to claim 28, comprising the step of utilizing a control unit to selectively generate and apply to each head unit a signal for acquiring an image.

30. A method according to claim 29, comprising the step of utilizing the control unit to generate and apply to each head unit at least one of (i) a shutter pulse defining at least a duration of charge integration by the respective charge coupled device, and (ii) a readout signal that effects output of charges from the respective readout sites.

31. A method according to claim 30, comprising the step of utilizing each head unit to respond to an applied shutter pulse for applying to the respective charge coupled device a reset signal for clearing the charge collection sites and for applying to the respective charge coupled device the transfer signal for causing charges accumulated on those sites to be transferred to the readout sites.

32. A method according to claim 30, comprising the step conditioning the image signals generated by the head units with a common video path.

33. A method according to claim 30, comprising the step of applying the shutter pulse substantially concurrently to each of the plurality of head units.

34. A method according to claim 30, comprising the step of applying the shutter pulse to each of the plurality of head units at substantially different respective times.

35. A method according to any of claims 33-34 comprising applying the readout signal to each of the plurality of head units at substantially different respective times.