Variable shift positive clamper

[erece]

for the given circuit and waveform , i am not getting how output for ωt < π is Vs + E1 ?
given Vs is input and equal to Vm Sinωt

 

[Carl Pugh]

When input voltage goes negative, C will charge to a negative voltage. There should be at least a large resistance resistor in series with C to keep it from charging to full voltage.
This is not my speciality, so there is no guarantee that this circuit will work even with a large resistance resistor in series with C.