High-end KVM switching system

• US 6,388,658 B1
• Filed: 12/02/1999
• Issued: 05/14/2002
• Est. Priority Date: 05/26/1999
• Status: Expired due to Term

• Current Assignee: Vertiv IT Systems, Inc. (Vertiv Holdings Co.)
• Original Assignee: Cybex Computer Products Corporation (Vertiv Holdings Co.)
• Inventors: Curran, John, Langejurgen, Stefan, Ahern, Steven M., Patzelt, Andreas, Egan, Colm, Szczepanek, Andreas, Malinowski, Klaus, Lischewski, Anton, Williams, Charles H.
• Primary Examiner(s): WU, XIAO MIN
• Application Number:
  US09/452,449
• Time in Patent Office: 894 Days
• Field of Search: 345/168, 345/169, 345/170, 345/171, 345/156, 345/157, 345/1.1, 345/1.2, 345/2.1, 345/2.2, 345/2.3, 345/3.1, 345/3.2, 345/3.3, 345/3.4, 345/4, 345/5, 341/20, 341/22, 341/23
• US Class Current: 345/168
• CPC Class Codes: G06F 13/4022 using switching circuits, e.g. switching matrix, connection or expansion network G06F13/4009 takes precedence
• CPC Class Codes: H04N 7/152 Multipoint control units therefor

Abstract

The present invention relates to a switching system for interconnecting a plurality of computer user terminals or workstations each having user interface devices, including a keyboard, a video display unit, and a cursor control device or mouse (KVM), with a plurality of computers in a computer network, allowing a user to access any one or more of said computers from the user interface devices of a single terminal or workstation. It is denoted “high end” because of the potentially large number of computers which may be interconnected with the system.

Claims

1. A switching system for interconnecting a plurality of computer user terminals, having user interface devices including a keyboard, a video display unit and a cursor control device, with a plurality of computers in a computer network, allowing a user to access any one or more of said computers from the user interface devices or a single terminal, comprising:

a switching hub for routing keyboard and cursor control signals transmitted from any one of the terminals to a selected computer, and for routing video signals received from the said computer to said one of the terminals, said signals being in both digital and analogue form,

a user interface module for receiving said transmitted keyboard and cursor control signals, coupled between said plurality of computer user terminals and said switching hub,

a computer interface module for receiving said received video signals, coupled between said plurality of computers and said switching hub,

wherein the physical architecture of the switching hub includes a modular system comprising a plurality of hot swappable switch modules, each module comprising an analogue transmitter circuit and/or an analogue receiver circuit, each including an analogue crosspoint switching arrangement, a programmable digital circuit for handling digital data signals and including a digital crosspoint switching arrangement, and a backplane interface between the said analogue and digital circuits.

2. A switching system according to claim 1, in which the digital circuit of each switching module comprises its own central processing unit adapted to provide distributed control of each switch module in the switching system.

3. A switching system according to claim 1, in which the digital circuit is bi-directional and is adapted to handle received or transmitted digital data signals, and is common to all switch modules.

4. A switching system according to claim 1, in which each switch module is configured as either a transmitter module or a receiver module.

5. A switching system according to claim 1, wherein each switch module provides access to a pre-determined number of computer user terminals or computers.

6. A switching system according to claim 1, in which the horizontal synchronization (HS) and vertical synchronization (VS) parts of the video signal are digitally encoded and handled by said digital circuit.

7. A switching system according to claim 1, in which internal communication between the an analogue transmitter or receiver circuit and the digital circuit is via an internal system bus.

8. A switching system according to claim 7, wherein the internal system bus is a differential controller area network (CAN) bus.

9. A switching system according to claim 1, in which the analogue crosspoint switching arrangement comprises a switch topology based on a switched transconductance architecture.

10. A switching system according to claim 9, in which the analogue crosspoint switching arrangement comprises a low power, large matrix crosspoint switch with high input resistance, low input capacitance and wide bandwidth.

11. A switching system according to claim 10, in which the analogue crosspoint switching arrangement comprises a plurality of multiplexers, each comprising a folded-cascode high-speed voltage feedback amplifier.

12. A switching system according to claim 1, wherein the digital crosspoint switching arrangement comprises a field programmable gate array.

13. A switching system according to claim 12, wherein the digital crosspoint switch arrangement is controlled by the central processing unit on its switch module, via separate address, data and control buses.

14. A switching system according to claim 1, wherein communication between the digital crosspoint switch arrangement and the backplane is via a differential transceiver, preferably a low voltage differential driver/receiver.

15. A switching system according to claim 5, wherein each switch module can handle sixteen video channels, such that a minimum of eight switch modules will allow sixteen computer user terminals to access 128 computers in a non-blocking way.

16. A switching system according to claim 15, wherein the digital crosspoint switching arrangement comprises two bi-directional 16×

16 gate arrays adapted simultaneously to handle respective HS and VS signal data, pertaining to one video channel.

17. A switching system according to claim 16, in which the analogue crosspoint switching arrangement comprises an array of 128 transconductance input stages organized as eight 16×

1, or two 16×

8, multiplexers with a common, 16-line analogue input bus.

18. A switching system according to claim 1, in which each multiplexer switching hub further comprises a programmable control panel module in communication with the backplane for system reconfiguration, and display of status information.

19. A switching system according to claim 18, in which the control panel module is adapted to interface with a remotely-linked input/output device, linked via infrared or radio, and/or is adapted to interface with a remotely-located computer user terminal.

20. A switching system according to claim 1, in which each switch module, is adapted to be hot-swappable.

21. A switching system according to claim 1, further comprising a fully-redundant power supply comprising multiple power supply units wherein each power supply unit is adapted to be hot-swappable.

22. A switching system according to claim 1, further comprising multiple cooling fan modules, wherein each cooling fan module is adapted to be hot-swappable.

23. A switching system according to claim 1, for interconnecting a plurality of computer user terminals, having user interface devices including a keyboard, a video display unit and a cursor control device, with a plurality of computers in a computer network, allowing a user to access any one or more of said computers from the user interface devices or a single terminal, comprising:

a switching hub for routing keyboard and cursor control signals transmitted from any one of the terminals to a selected computer, and for routing video signals received from the said computer to said one of the terminals, said signals being in both digital and analogue form,

a user interface module for receiving said transmitted keyboard and cursor control signals, coupled between said plurality of computer user terminals and said switching hub,

a computer interface module for receiving said received video signals, coupled between said plurality of computers and said switching hub.

24. A switching system according to claim 23, in which the analogue crosspoint switching arrangement comprises a low power, large matrix crosspoint switch with high input resistance, low input capacitance and wide bandwidth.

25. A switching system according to claim 24, in which the analogue crosspoint switching arrangement comprises a plurality of multiplexers, each comprising a folded-cascode high-speed voltage feedback amplifier.

26. A switching system according to claim 25, in which the analogue crosspoint switching arrangement comprises an array of 128 transconductance input stages organized as eight 16×

1, or two 16×

8 multiplexers with a common, 16-line analogue input bus.

27. A switching system for interconnecting a plurality of computer user terminals, having user interface devices including a keyboard, a video display unit and a cursor control device, with a plurality of computers in a computer network, allowing a user to access any one or more of said computers from the user interface devices or a single terminal, comprising:

a switching hub for routing keyboard and cursor control signals transmitted from any one of the terminals to a selected computer, and for routing video signals received from the said computer to said one of the terminals, said signals being in both digital and analogue form;

a user interface module for receiving said transmitted keyboard and cursor control signals, coupled between said plurality of computer user terminals and said switching hub;

a computer interface module for receiving said received video signals, coupled between said plurality of computers and said switching hub;

wherein the switching hub comprises a plurality of removable and hot swappable switch modules each with its own crosspoint switching arrangement and central processing unit, each module comprising an analogue transmitter circuit and/or an analogue receiver circuit, a programmable digital circuit for handling digital data signals, and a backplane interface between the said analogue and digital circuits.

28. A switching system for interconnecting a plurality of computer user terminals, having user interface devices including a keyboard, a video display unit and a cursor control device, with a plurality of computers in a computer network, allowing a user to access any one or more of said computers from the user interface devices or a single terminal, comprising:

a switching hub for routing keyboard and cursor control signals transmitted from any one of the terminals to a selected computer, and for routing video signals received from the said computer to said one of the terminals, said signals being in both digital and analogue form,

a user interface module for receiving said transmitted keyboard and cursor control signals, coupled between said plurality of computer user terminals and said switching hub,

a computer interface module for receiving video signals, coupled between said plurality of computers and said switching hub,

wherein the switching hub is a module system comprising a plurality of switch modules, each module comprising a separate analogue transmitter circuit or an analogue receiver circuit, each including an analogue crosspoint switching arrangement, a separate programmable digital circuit for handling digital data signals and including a digital crosspoint switching arrangement, and a backplane interface between the said analogue and digital circuits, said analogue circuit embodying stripline structures for video bus channel paths.

29. A switching system according to claim 28, in which adjacent channel paths are interleaved in an alternate tri-plate stripline structure, with even channels carried in one stripline structure and odd channels carried in the next adjacent stripline structure.

30. A switching system according to claim 28, in which the backplane is interconnected to the analogue circuit with a specific pin assignment wherein each analogue signal carrying pin is encircled by pins to ground thereby creating a pseudo-coaxial cavity for each analogue signal pathway within the mated backplane connector portion, for optimal crosstalk separation within said connector portion.

31. A switching system according to claim 28, in which galvanic isolation is incorporated in all interface paths between the analogue circuit and the digital circuit, preferably embodied by an opto-coupler.