Infrared heart rate measuring instrument

The invention provides an infrared heart rate measuring instrument. The instrument comprises a sensor part, an infrared transmitting tube in a sensor continuously transmits infrared rays, the infraredrays transmitted by the infrared transmitting tube penetrate through artery blood vessels and are reflected back through finger phalanges, the intensity of a reflected signal changes along with the change of blood flow, a receiving tube converts the signal into a weak electric signal, a circuit processing part consists of an infrared photoelectric switch, a voltage follower, an amplifier, a low-pass filter and a secondary amplifier circuit, an infrared photoelectric switch detects the influence of vibration of finger pulse on infrared rays emitted by the infrared emitting tube, the receivingtube converts an optical signal into an electric signal and outputs the electric signal at an output end, the operational amplifier amplifies the signal, filters out 50HZ power supply noise interference, and amplifies the filt