Why is my phone at full brightness and still dims

[AC Question]

I have my phone in full brightness and it still gets dim and its on auto I have the pptv king 7 someone help

 

[belodion]

Does the trouble persist in Safe Mode?

 

[ManiacJoe]

At a quick glance, being on "auto brightness" would suggest why the phone dims.
Does it work the way you desire when not on "auto brightness"?

Which phone?
Which version of android?
Which carrier?
Do you have any third-party screen dimming apps installed? (Lux, Twilight, etc.)