Charge pump power supply with noise control

• US 7,019,783 B2
• Filed: 10/04/2004
• Issued: 03/28/2006
• Est. Priority Date: 10/02/2003
• Status: Active Grant

• Current Assignee: Digirad Health, Inc. (Star Equity Holdings, Inc.)
• Original Assignee: Digirad Corporation
• Inventors: Kindem, Joel, Carlson, Lars S.
• Primary Examiner(s): HO, TUAN V
• Application Number:
  US10/958,689
• Publication Number:
  US 20050157193A1
• Time in Patent Office: 540 Days
• Field of Search: 348/372
• US Class Current: 348/372
• CPC Class Codes: H04N 25/00 Circuitry of solid-state image sensors [SSIS]; Control thereof
• CPC Class Codes: H04N 25/709 Circuitry for control of the power supply

Abstract

An embedded power supply for providing a voltage on a detector module within an imaging system provides the required potential to the module from charge stored on an output capacitor. Charge on the capacitor is replenished by injecting, commonly referred to as pumping, current into the capacitor by pulses of current generated by switching mode circuitry. Charge pumping into the capacitor is efficient because energy is stored in low-loss passive components and transferred into the low-loss output capacitor through low-impedance paths. Switching noise of the power supply is eliminated by turning off the charge pumping circuit during periods when such noise would disrupt the operation of the module, for example when the module is reading out image data. The output capacitor is large enough to supply the required voltage to the module for a certain period when the capacitor is not being pumped.

Claims

1. A method, comprising:

operating an image sensor device in a way that acquires image information during a specified portion of an operation;

driving at least a portion of said image sensor using a switched power supply which produces switching noise; and

not operating said switched power supply during times when the image information is being acquired.

2. A method as in claim 1, further comprising image processing the image information, and not operating said switched power supply during times when said image processing is being carried out.

3. A method as in claim 1, further comprising storing power from a switched power supply, and using the stored power during said specified portion when the image information is being acquired.

4. A method as in claim 1, wherein said switched power supply comprises a charge pump.

5. A method as in claim 1, further comprising regulating the voltage from the switched power supply.

6. A method as in claim 5, wherein said regulating comprises limiting a voltage output from the switched power supply.

7. A method as in claim 2, wherein said operating an image sensor device comprises obtaining image information from the image sensor device.

8. A method as in claim 2, wherein said operating an image sensor device comprises acquiring gamma rays using a gamma ray camera.

9. A method as in claim 1, wherein said operating comprises turning on the switching by the power supply for a time less than 1/10 as long as a time when the power supply is switched off.

10. A system, comprising:

a switched power supply circuit including a controllable switch, which is turned on and off to respectively produce power output, and a power storage part, which stores the power from said power output;

an image sensor, which acquires image information during only a portion of its time of operation; and

a controller for said switched power supply, which controls said switched power supply to produce said power output only during a time when the image information is not being acquired.

11. An image sensor as in claim 10, further comprising an image processing module that image processes the image information, and wherein said controller also prevents said switched power supply from producing said power output during said times when said image processing module is processing the image.

12. An image sensor as in claim 10, wherein said switched power supply includes a charge pump.

13. An image sensor as in claim 10, wherein said power storage part stores power, and said image sensor operates based on said stored power during times when the image information is being acquired.

14. An image sensor as in claim 10, wherein said power storage part is sufficiently large to store power to operate for an entire cycle of operation of said image sensor.

15. An image sensor as in claim 13, wherein said power supply operates from said stored power for at least 10 times as long as it operates from applied power, and said power storage part is sufficiently large to store power for said time of operating from stored power.

16. An image sensor as in claim 12, wherein said charge pump includes a transistor, and a capacitor, with the transistor switching power to the capacitor.

17. An image sensor as in claim 10, wherein said image sensor includes a gamma ray sensing device.

24. A module as in claim 17, wherein said power supply means includes a charge storage part, which stores power.

26. A module as in claim 24, wherein said charge storage part stores power for a time long enough for said switching to be off for at least 10 times as long as it is on.

18. An imaging module comprising:

means for detecting a signal for use in an imaging system; and

power supply means, associated with said detecting means, and generating a voltage for use by said detecting means; and

means for supplying the desired voltage for a specified period of time without simultaneously generating switching noise, and for generating said switching noise at least at one time other than said specified period.

19. A module as in claim 18, wherein said power supply means is a switching power supply.

20. A module as in claim 19, wherein said supplying means comprises a controller which turns off switching during a time of said specified period.

21. A module as in claim 18, wherein said specified period is a time during which the detecting means detects a signal.

22. A module as in claim 20, wherein said controller includes a microprocessor.

23. A module as in claim 18, wherein said controller includes discrete circuitry.

25. A module as in claim 18, wherein said supplying means controls said switching to be off for 10 times as long as it is on, or more.