Safety light curtains are also known as photoelectric safety protection devices (also known as safety protectors, press protectors, infrared safety protection devices, etc.). In modern factories, people and machines work together, in some potentially dangerous machinery and equipment, such as stamping machinery, shearing equipment, metal cutting equipment, automated assembly lines, automated welding lines, mechanical transmission and handling equipment, hazardous areas (toxic, high-pressure, high-temperature, etc.), which can easily result in personal injury to the operator. When an operator is feeding or removing material, any part of the body that blocks the light will cause the machine to go into a safe state without causing injury to the operator. Safety light curtains are safety-certified light curtain products that consist of two parts: a light thrower and a light receiver. The projector emits modulated infrared light, which is received by the light receiver, forming a protective net, when an object enters the protective net, when there is a light from it blocked by an object, through the internal control line, the light receiver circuit reacts immediately, i.e., a signal is output in the output section for machine tools such as punching machines, presses, etc., to apply emergency brakes.