Embodiments of the invention provide a conversion circuit, used for converting a current signal flowing through a sensing component into a first output voltage signal and comprising: a first current eliminating circuit, used for eliminating a first current in the current signal, wherein the first current eliminating circuit comprises a current sample-and-hold circuit; a current drive circuit, coupled between the sensing component and the current sample-and-hold circuit; a second current eliminating circuit, coupled to the sensing component and used for eliminating a second current in the current signal; and an integrating circuit, coupled to the sensing component and used for integrating a third current in the current signal and outputting the first output voltage signal between a first integration output end and a second integration output end. According to the embodiments of the invention, a backlight current and a background current in a current signal can be eliminated, and a heartbeat current in the curr
