| 摘要 |
PROBLEM TO BE SOLVED: To prevent unnecessary consumption of a battery by arbitrarily adjusting the strength of illumination according to the brightness of the surroundings, and to adjust the illumination according to the tastes of a user. SOLUTION: A portable telephone set 2 is provided with a radio part 4 for operating transmission and reception with a radio base, an operating part 6 constituted of plural keys for inputting a telephone number, a display part 8 for displaying the telephone number and the other information, and a control part 10 for controlling each part of the portable telephone set 2, and this portable telephone set 2 is operated with a battery as a power source. Then, when a user operates an illumination adjusting key 14, the control part 10 changes the resistance value of a variable resistor 16 based on an operation corresponding to the illuminating adjusting key 14. Thus, currents to be supplied to an illuminating circuit 12 can be changed, and the strength of the illumination of the operating part 6 and the display 8 by the illuminating circuit 12 can be changed. |
