Patent 7522426 was granted and assigned to Hitachi on April, 2009 by the United States Patent and Trademark Office.
A backplane has signal connectors for connecting signals of logical boards connected to an upper level of the backplane; signal connectors for connecting signals of logical boards connected to a lower level of the backplane; power source connectors for supplying power to the logical boards connected to the upper level of the backplane; and power source connectors for supplying power to the logical boards connected to the lower level of the backplane. Some power source connectors are formed at one end of the backplane and the other power source connectors are formed at the other end of the backplane.