At default setting in Windows , when you don't make activity for a specified time , not use the keyboard, mouse, or touch screen, the display will off automatically. This function is useful for energy saving. You can find this setting is in the Power Options section. .
There is a question : 'How to turn off the display directly/manually?, not wait for specified time..'.
The answer: You can use the Power button and configure it so that if pressed, it can turn off the display.
Here are the steps:
1. Press Windows + R (to open Run Command), write powercfg.cpl at the run column, and hit/press Enter or click OK.
Power Options window will appear.
2. Select 'Choose what the power button does'.
3. At the section 'When I press the power button', choose 'Turn off the display', (On battery and also on Plug in)
4. Click 'Save Changes' to save configuration.
Now when your laptop running, and then you press the power button, the display will turn off.
To turn on it again, press any key or move the mouse.