5.0 lollipop - How to keep my screen light on during the call (Nexus 4, Android 5.1.1)

I have a Nexus 4 (Android 5.1.1). My proximity sensor does not work well. I don't have any cover. The distance it detects is always 0 cm.

1. 
   

   One solution I found is turn on "Power button ends call". However I need use my keyboard during the call.

   
   


2. 
   

   I also tried some proximity sensor reset apps, but they do not work on my phone.

   
   


3. 
   
   

   One solution I found is to keep the screen light on. But I don't have this setting on my phone.

   
   

Is there any other way to keep my screen light on during the call or other solutions? Thanks