Patent ID: 7589436

Claim:
A data processing unit comprising: a rack separated vertically into multiple storage sections by partitions; a DC backup power supply including a secondary battery section and a charging/discharging control section stored in the bottom storage section of the rack; a data processor section equipped with a hard disk drive stored in a higher storage section than the DC backup power supply; a primary fan for ventilation from the bottom to the top, mounted in a higher storage section than the bottom section; vents formed in the partition closest to the bottom storage section storing the DC backup power supply; and wherein the secondary battery section is provided with a rectangular parallelepiped battery pack containing multiple secondary batteries and the battery pack is mounted upright so that the shortest sides of the rectangular parallelepiped are positioned at the top and bottom, wherein the primary fan is mounted in the top storage section of the rack and there is also provided an AC/DC converter converting the alternating current from a commercial power source to direct current mounted in a storage section above the bottom storage section and a secondary fan for the ventilation from the bottom to the top mounted adjacent to the AC/DC converter and powered by the AC/DC converter, wherein power is supplied from the AC/DC converter to the primary and secondary fans when the commercial power source is alive and power is supplied only to the primary fan from the DC backup power supply when the commercial power source has failed.