Proximity detector and radiography system

• US 6,985,556 B2
• Filed: 08/13/2003
• Issued: 01/10/2006
• Est. Priority Date: 12/27/2002
• Status: Expired due to Fees

• Current Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Original Assignee: GE Medical Systems Global Technology Company LLC (GE Healthcare Technologies, Inc.)
• Inventors: Krishnaswami, Hariharan, Shanmugavel, Giridharan
• Primary Examiner(s): Glick, Edward J.
• Assistant Examiner(s): Kao, Chih-Cheng Glen
• Application Number:
  US10/639,882
• Publication Number:
  US 20040125918A1
• Time in Patent Office: 881 Days
• Field of Search: 378/91, 378/114, 378/117, 378/196, 378/197, 378/205, 324/661, 324/662, 324/668, 324/663, 324/678, 324/679, 324/686, 324/687, 324/658, 340/540, 340/541, 340/561, 340/562, 250/363.02, 250/363.03, 250/363.04, 250/363.05, 250/363.08
• US Class Current: 378/117
• CPC Class Codes: A61B 6/102 Protection against mechanical damage, e.g. anti-collision devices

Abstract

Certain embodiments of the present invention provide a proximity detector having a simple configuration and an imaging system including the proximity detector. In an embodiment, a proximity detector mainly comprises: a single electrode mounted on a subject-side end of a movable member; a current feeding device for feeding a constant current to an electrostatic capacitor formed between the electrode and a ground; a discharging device for releasing charge from the electrostatic capacitor at intervals of a certain cycle; a binary-coding device for binary-coding the potential at the electrode relative to a ground based on a threshold; and a smoothing device for smoothing an output signal of the binary-coding device.

Claims

1. An imaging system, said imaging system comprising:

a movable member capable of approaching a subject; and

a proximity detector, said proximity detector indicating an approach of said movable member within a certain distance of said subject based on an electric field, said proximity detector comprising;

an electrode mounted on said movable member;

a current feeding device for feeding a constant current to an electrostatic capacitor formed between said electrode and a ground; and

a discharging device for releasing charge from said electrostatic capacitor at intervals of a certain cycle,

wherein said electrode comprises two conductive layers electrically isolated from each other, and said constant current is fed to an outer layer of said conductive layers, and a voltage equal to a first voltage applied to said outer layer is applied to an inner layer.

2. The system of claim 1, wherein said proximity detector further comprises:

a binary-coding device for binary-coding a potential at said electrode relative to a ground based on a threshold; and

a smoothing device for smoothing an output signal of said binary-coding device.

3. The system of claim 1, further comprising an x-ray irradiating device and an x-ray receiving device supported by said movable member, said x-ray irradiating device and said x-ray receiving device positioned opposed to each other with a space there between.

4. The system of claim 3, wherein said electrode is formed along a perimeter of a receiving surface of said x-ray receiving device.

5. The system of claim 3, wherein said electrode is formed over an outer periphery of said x-ray receiving device and a perimeter of a receiving surface thereof.

6. The system of claim 3, wherein said x-ray receiving device comprises an image intensifier.

7. The system of claim 1, wherein said movable member comprises a C-arm.

8. The system of claim 1, wherein said imaging system comprises a sensing circuit mounted on the same movable member as the electrode.

9. A proximity detector, said proximity detector comprising:

an electrode positioned on a surface of a movable member;

a current feeding device for feeding a constant current to an electrostatic capacitor formed between said electrode and a ground;

a discharging device for releasing charge from said electrostatic capacitor at intervals of a certain cycle; and

a proximity detection device triggering an alert based on a threshold,

wherein said electrode comprises two conductive layers electrically isolated from each other, and said constant current is fed to an outer layer of said conductive layers, and a voltage equal to a first voltage applied to said outer layer is applied to an inner layer.

10. The proximity detector of claim 9, wherein said alert comprises at least one of an alarm, a log, and a motion halt command.

11. The proximity detector of claim 9, wherein said proximity detector further comprises:

a binary-coding device for binary-coding a potential at said electrode relative to a ground based on a threshold; and

a smoothing device for smoothing an output signal of said binary-coding device.

12. The proximity detector of claim 9, wherein the proximity detector is used with an x-ray irradiating device and an x-ray receiving device supported by a supporting device, said x-ray irradiating device and said x-ray receiving device positioned opposed to each other with a space therebetween.

13. The proximity detector of claim 12, wherein said electrode is formed along a perimeter of a receiving surface of said x-ray receiving device.

14. The proximity detector of claim 12, wherein said electrode is formed over an outer periphery of said x-ray receiving device and a perimeter of a receiving surface thereof.

15. The proximity detector of claim 9, wherein said proximity detector uses a ramp and pedestal method to detect a change in capacitance.

16. The proximity sensor of claim 9, wherein said proximity detector comprises a sensing circuit positioned on the same movable member as the electrode.

17. A method for proximity detection, said method comprising:

positioning an electrode on a surface of a movable member, wherein said electrode comprises two conductive layers electrically isolated from each other;

forming an electrostatic capacitor between said electrode and a ground;

feeding a constant current to said electrostatic capacitor, wherein said feeding step feeds said constant current to an outer layer of said conductive layers;

releasing a charge from said electrostatic capacitor at certain intervals;

comparing a voltage across said electrode to a reference signal to form a proximity detection signal;

triggering an alert if said proximity detection signal does not satisfy a certain threshold; and

applying a voltage equal to a first voltage applied to said outer layer to an inner layer.

18. The method of claim 17, wherein said comparing step further comprises:

generating a binary signal based on said voltage and said reference signal; and

smoothing said binary signal to form a proximity detection signal.

19. The method of claim 17, further comprising:

positioning a patient; and

triggering an alert when said surface approaches said patient within a certain threshold distance based on said proximity detection signal.

20. The method of claim 17, wherein said positioning step further comprises positioning a sensing circuit on the same surface movable member as the electrode.