| 摘要 |
<p>PROBLEM TO BE SOLVED: To increase the workable time of a portable information processor that is driven by a battery in particular by reducing the power that is used for illumination of a display device even while the information processor is operating. SOLUTION: An input detection means 12 detects the presence or absence of the input supplied from a keyboard 10 and a mouse 11, and an input interval decision means 13 compares the time intervals set previously with each other. When the input lasts, the power supplied to a back light 15 is gradually reduced in a power drop mode 14b. Thus the brightness of the light 15 is reduced in such a degree where a user is not conscious of it. When no input is supplied during a set time interval, the light 15 is turned off in a lights-out mode 14c. When the input is started again, the power is supplied to the light 15 in an initial lighting mode 14a. Thus the light 15 is turned on in the initial luminance, and the mode 14a is switched again to the mode 14b.</p> |
