Why do laser printers need to detect high voltage and low current?

Laser printers detect high voltage and low current to reduce interference. The invention discloses a high voltage and small current detection circuit, which comprises an amplification unit, a current detection unit, a first interference loop, a second interference loop and a load, wherein the load is electrically connected with the first interference loop and the second interference loop respectively; the input end of the current detection unit is electrically connected with the first interference loop and the second interference loop respectively; and the output end of the current detection unit outputs a detection current to the amplification unit. The amplifying unit amplifies the detected current and outputs it to the external main control board. A DEV high-voltage power supply is connected in parallel in the first interference loop, and a TAR high-voltage power supply is connected in parallel in the second interference loop. The patent circuit structure of the utility model is simple and reliable, which can prevent stray interference current from passing through the detection circuit, improve the stability of output voltage and the accuracy of current detection, reduce the area of auxiliary circuit and PCB, and reduce the production and design cost of the circuit. And that production and design cost of the circuit are reduce. And that production and design cost of the circuit are reduce.