照有些说法：系统－＞首选项－＞电源管理 可以调 但我的不行，如下图
解决方法：1 在终端输入sudo gedit /etc/default/acpi-support
将 ENABLE_LAPTOP_MODE=false 改为 ENABLE_LAPTOP_MODE=true
2 在终端输入sudo gedit /etc/laptop-mode/laptop-mode.conf
交流电模式下使用 laptop mode
#
# Enable laptop mode when on AC power.
#
将 ENABLE_LAPTOP_MODE_ON_AC=0 改为 ENABLE_LAPTOP_MODE_ON_AC=1
＃电池那也可设为1
使用 laptop mode 进行LCD亮度控制
#
# Should laptop mode tools control LCD brightness?
#
将 CONTROL_BRIGHTNESS=0 改为 CONTROL_BRIGHTNESS=1
#
# Commands to execute to set the brightness on your LCD
#
BATT_BRIGHTNESS_COMMAND="echo 4"
LM_AC_BRIGHTNESS_COMMAND="echo 4" “““我的亮度范围是0－7的”””
NOLM_AC_BRIGHTNESS_COMMAND="echo 4"
BRIGHTNESS_OUTPUT="＊＊＊＊＊＊＊＊＊＊＊＊＊＊/brightness"#注意这里＊＊＊＊＊＊＊＊＊根据下面的来添（我选了第二种）
＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊
# * If your system has the file "/proc/acpi/video/VID/LCD/brightness" (VID may
# be VID1 or similar), use this file as BRIGHTNESS_OUTPUT, and use
# the command "echo <value>". The possible values can be listed using the
# command:
#
# cat /proc/acpi/video/VID/LCD/brightness
# * If you have a file /sys/class/backlight/.../brightness, then you can use
# that file as BRIGHTNESS_OUTPUT, and the command "echo <value>".
#
# As far as I understand it the values are between 0 and
# the value contained in the file /sys/class/backlight/.../max_brightness.