| 摘要 |
PURPOSE:To avoid damage of a pattern in replacement of display devices and to make it possible to maintain reliability by providing through-hole plating holes for attaching a liquid-crystal display device on the other side of a printed wiring board on one side of which a liquid-crystal display device is attached, and connection the holes with a pattern. CONSTITUTION:The following parts are attached to the inside of a cover 2 of this watthour meter 1 from the front surface: a transparent glass plate 2b; a name plate 3A on one side of which square holes 3a are provided; and a rectangular light shielding plate 4 for preventing the input of ultraviolet rays from the outside. The attaching surface of a liquid crystal display device 6A is directed to the light shielding plate 4, and a printed wiring board 5 is attached. A through-hole plating hole 5b is provided at the symmetrical position of a through-hole plating hole 5a for attaching the provided display device 6A in said wiring board 5. Both holes are connected with a pattern 5c. Since a solder iron is applied in the hole 5a in replacing the display device. The display device 6A is disconnected and a display device 6B is soldered; the number of applications of the soldering iron on the holes 5a and 5b is decreased and the damages of the plated parts of the holes 5a and 5b and the pattern 5c can be prevented. |
