An auto darkening filter, comprising: a first positive liquid crystal (LCD1) a second positive liquid crystal (LCD2); a first liquid crystal control circuit (A) configured to control the first positive liquid crystal (LCD1) and the second positive liquid crystal (LCD2) based on a received control signal; a negative-phase liquid crystal (LCD3) provided between the first positive liquid crystal (LCD1) and the second positive liquid crystal (LCD2); a second liquid crystal control circuit (B) configured to control the negative-phase liquid crystal (LCD3) based on a received control signal; a UV/IR filter configured to filter a welding arc; a light control circuit configured to detect the welding arc, generate a corresponding control signal based on the detected intensity of the welding arc, and output the corresponding control signal to a main control circuit.