Shenzhen PM-9000 Express, Service Manual

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Chapter 2 Principles
Motor Drive Circuit
This circuit controls the action of the air pump. It, together with the Valve Drive Circuit,
implements the inflation and deflation of the cuff. Besides, it provides the status signal of the
motor for the A/D conversion part.
NIBP Signal Process Network
The NIBP signal is the differential input signal. The difference amplifying circuit amplifies the
dual-end difference signal and converts it to the single-end signal; meanwhile, this circuit
sends a channel of signal to the A/D conversion part, and the other to the DC isolating and
amplifying circuit.
The DC isolating and amplifying circuit removes DC components from the signal, amplifies the
signal, and then sends it to the A/D conversion part.
A/D
The A/D conversion part converts the analog signal to the digital signal, and sends it to the
CPU System for further processing.
Over Pressure Detect
The circuit detects the NIBP pressure signal. Once the pressure value exceeds the protected
pressure value, it will send a message to the CPU System, which asks the Valve Drive Circuit
to open the valve to deflate the cuff.
CPU System
Implementing the logical control of all the circuits;
Implementing the data processing for the NIBP parameter;
Implementing the communication with the main board.
2.2.6 Recorder Module
2.2.6.1 General
This module is used to drive the heat-sensitive printer.
2.2.6.2 Principle diagram
Figure 2-9 Working principle of the recorder module
2.2.6.3 Principle
This module receives the to-be-printed data from the main board, converts them to the dot
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