| 摘要 |
PURPOSE:To avoid useless power consumption and to improve the battery service life by extinguishing display when the surrounding is dark such a state in a pocket or in a dark room and implementing the display only when the surrounding is bright. CONSTITUTION:After the end of message reception, a CPU 7 sends a signal to a decoder 3, which activates the notice by a speaker 12, an LED 13 or a motor 14 and drives an LED driver 8 to display a reception message onto an LCD 9. On the other hand, the decoder 3 applies interrupt to a CPU 7 with an output signal depending on the dark state from a light receiving circuit 15 to allow the CPU 7 to discriminate whether or not a driver 8 is to be driven. A photo transistor(TR) of the light receiving circuit 15 is turned on when the surrounding is bright and turned off when dark, and an H and an L level are respectively outputted to the decoder 3. The decoder 3 applies interruption to the CPU 7 only when the level of the signal changes from H to L and from L to H. Thus, the display is extinguished when the surrounding of the receiver is dark. |
