| 摘要 |
PROBLEM TO BE SOLVED: To provide a battery pack having a printed portion capable of being visually recognized with ease, if necessary, by reducing temperature, while the color tone of an outer package and the printed portion and the forming position of the printed portion are not limited, the thickness of the outer package can be reduced, and good design properties are achieved.SOLUTION: In a battery core 2, a protective circuit board 4 is located on a second side face 3b of a battery 3 of a battery pack 1. The content of information such as manufacturing information is printed on the surface of the battery 3 by a thermochromic ink, and thereby, a printed portion 5 is formed. The thermochromic ink is in a color-developed state at ordinary temperature. When temperature is increased, the ink is decolored at a predetermined temperature or higher and maintains a decolored state. When the temperature is decreased, the ink develops color at a predetermined temperature or below wherein the predetermined temperature is lower than ordinary temperature. After the second side face 3b and a side face parallel to the second side face are covered with an outer tape 6, the battery core 2 is housed in a heat shrinkable tube 12. By heating the battery core 2, the printed portion 5 turns into the decolored state and cannot be visually recognized from the outside. |
