| 摘要 |
Plural CPUs 20-1 through 20-6 are mounted on a circuit board 11, and heat sinks 30-1 through 30-6 are mounted on these CPUs, respectively. The CPUs 20-1 through 20-6 are cooled by an air flow generated by motor fan units 14-1, 14-2, 15-1, and 15-2. The CPUs 20-1 through 20-6 are arranged such that a ratio of a sectional clearance area at the downstream side of the air flow to a sectional area of a tunnel 12 is lower than a corresponding ratio at the upstream side of the air flow. This clearance is formed between a cover member 13 and the heat sinks 30-1 through 30-6. Air flow passages 85 and 86 are formed at both sides at the upstream side. By the air flow passages 85 and 86, the amount of fresh air that is sent to the heat sinks 30-5 and 30-6 at the downstream side is increased. Accordingly, the cooling of the CPUs 20-5 and 20-6 at the downstream side is promoted compared to the conventional case. <IMAGE> |
