Camera system including a safety circuit

• US 7,136,105 B2
• Filed: 07/06/2001
• Issued: 11/14/2006
• Est. Priority Date: 07/06/2000
• Status: Expired due to Fees

• Current Assignee: Gvbb Holdings SARL (Vislink Technologies, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Van Buul, Marinus C. W., Schmale, Peter C.
• Primary Examiner(s): Vu, Ngoc-Yen
• Assistant Examiner(s): Giles, Nicholas G
• Application Number:
  US10/332,308
• Publication Number:
  US 20030142230A1
• Time in Patent Office: 1,957 Days
• Field of Search: 348/372, 396/279, 396/303, 361/49, 320/112, 320/114
• US Class Current: 348/372
• CPC Class Codes: H02H 1/003 Fault detection by injection of an auxiliary voltage same for detection of earth fault currents H02H3/17; for monitoring earth connection H02H5/105
• CPC Class Codes: H02H 3/12 responsive to underload or no-load for motors H02H7/0827
• CPC Class Codes: H04N 23/66 Remote control of cameras or camera parts, e.g. by remote control devices

Abstract

Camera systems are often built up from a base station, a detachable cable, and a camera. A dangerous situation may arise the moment the cable is detached from the camera because there is (still) a voltage present on the cable. The invention provides a camera system in which this problem is solved by means of a safety circuit capable of detecting from the base station whether a camera is connected to the cable or not.

Claims

1. A camera system with a base station and a camera coupled to the base station by means of a detachable cable, the cable having at least two conductors, comprising:

the base station having a power supply means for providing power supply to the two conductors, a controlled switch for coupling or not power supply means with the conductors, a current injector connected in parallel to the two conductors, the current injector providing an AC current at a predetermined frequency, and a current detector connected in parallel to the two conductors, the current detector measuring the AC current at the predetermined frequency,

the camera having a means for short circuiting the AC current at the predetermined frequency.

2. The system of claim 1, where, in a first condition said base station and said camera are coupled via said cable and said current detector fails to detect said predetermined frequency and enables said power supply to said conductors, and in a second condition said base station and said camera head are not coupled via said cable, said current detector detects said predetermined frequency and disables said power supply to said conductors.

3. The system of claim 1, wherein power supply means provides a DC voltage.

4. The system of claim 3, wherein the base station comprises at least an impedance between the power supply means and the connection nodes of current injector and detector, said impedance being low ohmic for DC current and high-ohmic for AC current of the predetermined frequency.

5. The system of claim 3, wherein the base station comprises at least an impedance circuit between the power supply means and the connection nodes of current injector and detector, said impedance circuit being low-ohmic when a significant DC current flows into it, and being high-ohmic when the DC current is not significant.

6. The system of claim 1, wherein the means for short circuiting the AC current at the predetermined frequency is a capacitor.