| 摘要 |
PROBLEM TO BE SOLVED: To reduce a temperature rise in a coolant, and perform long hour operation by arranging plural metallic balls having large specific heat per unit volume in a reservoir of the coolant used to cool a device. SOLUTION: For example, an electronic optical device having an infrared ray detector 1 has prescribed metallic balls 9 in a reservoir 6 for storing a coolant 3 for circulating in a cooling part 4 and a heat radiating part. Heat is transmitted to outside air from the coolant 3 via the heat radiating part to lower the temperature of the coolant 3 and the metallic balls 9. Even if an operational condition of being small in heat radiation to the outside continues, a temperature rise in the coolant 3 is restrained by sensible heat of the metallic balls 9. This electronic optical device is constituted so as to use plural kinds of metallic balls different in a rate of specific heat to heat conductivity and plural kinds of metallic balls different in a ball diameter, and a hollow metallic ball for sealing a solid coolant having a melting point is also used in a transition temperature range of the coolant 3. Plural kinds of hollow metallic balls for sealing solid coolants different in a melting point may be used.
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