In this paper, we propose a general method for designing all-optical photonic crystal ternary inverters. Unlike conventional binary systems, ternary inverters operate logic functions using three distinct states, enabling faster and more efficient performance. The proposed structures incorporate threshold detectors based on nonlinear ring resonators, whose threshold values are tuned by adjusting the radii of embedded rods. To realize ternary logic operations, detectors with different threshold values are cascaded using a binary switch. The designs are evaluated using the finite-difference time-domain (FDTD) and plane-wave expansion (PWE) methods. Simulation results show that the propagation delay of the proposed all-optical ternary inverters is approximately 0.5 ps, with a compact footprint of less than 370?μm2.