Electric potential patterns are derived in the inner magnetosphere at 4 < L < 10 using 2 years of data from the Electron Drift Instrument (EDI) on Cluster. First, we examine the relations between the electric field and the following three parameters to understand how the potential patterns are organized: BZ component of the interplanetary magnetic field (IMF), Kp index, and Dst index. From these correlations we can determine the effect of the interplanetary electric field (IEF) on the inner magnetospheric electric field as measured by Cluster. Next, the electric field is related to a quantity proportional to the injection rate of the plasma sheet particles, F(Dst*) ≡ (dDst*/dt + 0.13Dst*), where the effect of the magnetopause current is removed in Dst*. Then we develop a method to obtain potential patterns. An inverse problem is solved by adjusting a trade-off parameter for smoothness of the result. The obtained potential patterns for three controlling parameters, IMF BZ, Kp index, and F(Dst*), are attached as supplemental material. We discuss the following features from these potential patterns: (1) potential drop, (2) rotation of the direction of the convection electric field, (3) dawn-dusk asymmetry of the strength of the electric field, and (4) size of the last closed equipotential (LCE). This initial study is relevant to the development of an empirical model of inner magnetospheric convection in the equatorial plane.