| 摘要 |
A control panel having a sheet-formed pushbutton unit that satisfies the requirements of hermeticity, clearness of indication and operability and yet allows a cost reduction. A single-cut sheet made of a commercially available light-transmitting thermoplastic synthetic resin material is used as a substrate. Sheet recesses are formed on the single-cut sheet so that each print layer formed on the surface of the single-cut sheet is located on the inner side of the bottom of a sheet recess to prepare a formed sheet. The sheet recesses are filled with a synthetic resin material to produce a key sheet having pushbuttons. The key sheet is thermowelded to the rear side of a case cover by ultrasonic vibrational energy to form an integral unit.
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