Iphone users will be accustomed to a voiceover feature called screen curtain which turns the display of the phone completely off. If you are blind, there are lots of reasons you might want to do this:
- Enhanced privacy
- increased battery life
- elimination of residual screen glare.
Stock android does not come with this feature by default. If you are using stock android such as that on nexus and motorola devices, the following apps will dim your screen beyond the system limit.
These have different feature sets and you will have to read and experiment to see which one you like. The only one that completely blacks the screen is screen filter according to the descriptions.
Modern Samsung devices have a feature named 'Dark Screen' which allows the user to turn of the display. The following Samsung devices have this functionality:
- Samsung Galaxy S4
- Samsung Galaxy S5
- Samsung Galaxy S5 Mini
- Samsung Galaxy Note 3
- Samsung Galaxy Note 4
An Eyes-Free list member has also said that the LG G3 has a similar functionality, though this information is presently not verified. Hopefully others will add to the list of devices, and provide additional information/references.