| 摘要 |
PROBLEM TO BE SOLVED: To make the sound of a buzzer easy to propagate by a method wherein a cylindrical protrusion which is extended downward so as to surround the side surface of a buzzer is provided in an upper outer frame and a plurality of air windows are formed an the surface of the upper outer frame which is surrounded by the cylindrical protrusion. SOLUTION: A cylindrical protrusion 9 which is extended downward, air windows 8 through which heat generated by an electronic component is discharged out and air windows 7 are provided in an upper outer frame 3. The cylindrical protrusion 9 is so formed as to surround the side surface of a buzzer 5 and a plurality of the air windows 7 are formed on the surface of the upper frame 3 which is surrounded by the cylindrical protrusion 9. If the buzzer 5 produces a sound through an aperture 6, as the buzzer 5 is surrounded by the inner wall of the cylindrical protrusion 9, the sound passes through the inside of the protrusion 9 and goes out through the air windows 7. Consequently, the sound pressure is not reduced and the buzzer sound can be heared easily. |
