Inkjet printing apparatus

1. An inkjet printing apparatus comprising:

an array of inkjet print heads, each print head comprising at least one ink port for receiving ink, at least one nozzle for directing ink onto a substrate to be printed, and at least one control terminal for receiving at least one of a supply voltage and control signals;

a print head mounting element which positions the print heads in a defined orientation relative to each other;

an electrical supply unit extending over the array and connected to the control terminals of all of said print heads, wherein said electrical supply unit can supply said at least one of a supply voltage and control signals to all of said print heads in common; and

a mechanical supply unit extending over the array and connected to the ink ports of all of said print heads, wherein said mechanical supply unit can supply ink to all of said print heads in common.

2. The inkjet printing apparatus of claim 1 wherein the electrical supply unit is of modular design and comprises a separate control card for each said print head, each said control card being connected to a control terminal of a respective said print head, the control cards of adjacent said print heads being connected to each other.

3. The inkjet printing apparatus of claim 2 wherein the control cards of adjacent said print heads are connected to each other to form a bus structure, each said control card having a plurality of sides from which said at least one of a supply voltage and control signals can be tapped for transmission to an adjacent control card.

4. The inkjet printing apparatus of claim 3 wherein said control cards of adjacent said print heads are connected to each other by flexible pin-and-socket connectors.

5. The inkjet printing apparatus of claim 1 further comprising a supply cable connecting said electrical supply unit to a control unit and a voltage source.

6. The inkjet printing apparatus of claim 1 wherein the mechanical supply unit comprises an ink container having openings connected to respective said ink ports, each said opening having a valve which can be opened and closed independently of other said valves.

7. The inkjet printing apparatus of claim 6 further comprising an ink reservoir connected to the ink container by an inflow line and an outflow line.

8. The inkjet printing apparatus of claim 6 further comprising flexible connecting pieces connecting respective said openings to respective said ink ports.

9. The inkjet printing apparatus of claim 6 further comprising partitions dividing the ink container into at least one feed container having ink outlets and at least one return container having ink inlets, said ink outlets being connected to respective said ink ports of said print heads, said ink inlets being connected to respective said openings of said ink container.

10. The inkjet printing apparatus according to claim 6 wherein the ink is supplied from the ink container to the print heads by gravity, the apparatus further comprising a vacuum line for degassing the ink container.

11. The inkjet printing apparatus of claim 6 further comprising an ink circulation system for supplying ink from the ink container to the print heads.

12. The inkjet printing apparatus of claim 1 wherein the print head mounting element is a flat plate designed so that all the print heads are the same distance from a substrate to be printed, wherein the substrate is carried on a flat path parallel to the plate.

13. The inkjet printing apparatus of claim 1 wherein the print head mounting element is a curved plate designed so that all the print heads are approximately the same distance from a substrate to be printed, wherein the substrate is carried on a curved path parallel to the plate.

14. The inkjet printing apparatus of claim 1 wherein the print head mounting element has recesses which receive respective said inkjet print heads, and stops adjacent to said recesses, wherein said stops define the orientation of the print heads relative to each other.