Shenzhen PM-9000 Express, Service Manual

Page: 25 / 80

Chapter 2 Principles
Implementing the logical control of all the circuits;
Implementing the data processing for the SpO
2
parameter;
Implementing the communication with the main board.
Power & Signal isolate Circuit
Isolating the external circuits to ensure the safety of human body;
Supplying power for all circuits;
Implementing the isolation communication between the CPU System and the main
board.
2.2.5 NIBP Module
2.2.5.1 General
This module provides the function of measuring the Non-Invasive Blood Pressure (NIBP)
parameter.
2.2.5.2 Principle diagram
Figure 2-8 Working principle of the NIBP module
2.2.5.3 Principle
The NIBP is measured based on the pulse vibration principle. Inflate the cuff which is on the
forearm till the cuff pressure blocks the arterial blood, and then deflate the cuff according to a
specified algorithm. While the cuff pressure is decreasing, the arterial blood has pulses, which
are sensed by the pressure transducer in the cuff. Consequently, the pressure transducer,
connected with the windpipe of the cuff, generates a pulsation signal, which is then processed
by the NIBP module to get the NIBP value.
Valve Drive Circuit
This circuit controls the status (ON/OFF) of valves. It, together with the Motor Drive Circuit,
implements the inflation and deflation of the cuff.
13