Gima ECG90A Manuel D'utilisation page 14

Chapter4 Working Principle and Structural Characteristics
4.1 Working principle and its block diagram
4.1.1 The power supply unit
Principle of power supply
After the AC power supply enters the switching power supply, it is converted to 12V DC
voltage and supplied to the main unit, it also provides constant voltage current limiting charging
for the rechargeable lithium battery in the device through the DC-DC circuit, and generates +5V
and +8.5V voltage through the power conversion to supply power to the corresponding modules.
At the same time, the lithium battery in the device can independently satisfy working
requirements of each module in the device through the buck-boost circuit.
Note: The principle block diagram and component list are only available to service
stations or maintenance personnel designated by our company.
4.1.2 Signal acquisition unit
The signal acquisition unit uses a floating setting, which is a signal acquisition and
processing system, including analog circuit part and 24-bit A/D conversion and data processing
part. The analog circuit consists of signal following, amplification, anti-aliasing low-pass
filtering, lead-off detection and overload detection. CPU system is responsible for coordinating
the work of each circuit such as the A/D converter, the lead-off detection circuit and the overload
detection circuit, in order to achieve signal acquisition, processing, and lead-off detection.
Control information and A/D conversion and data acquisition between the floating circuit and the
solid circuit are transmitted through the signal isolation circuit.
4.1.3 Control unit
（1）Principle of control unit
The control system consists of printing system, button system, liquid crystal display system,
and signal acquisition system. The ECG signal sent from the signal acquisition system through the
high-speed isolation circuit is received by the CPU system, after digital filtering, gain adjustment
and motor drive, it is sent to the printing system to print the ECG waveform. After the printing is
completed, the CPU system processes waveform measurement and analysis. The CPU system also
receives an interrupt signal and button code from the button system to complete the interrupt
processing. In addition, the lead-off signal, paper out detection, battery voltage management, and
automatic power-off are also managed by the CPU system. The liquid crystal controller receives
data and commands from the CPU system to complete the display of the control state of the device.
（2）Principle block diagram is shown in Figure4-1.
Button system
Printing system
Control system
Power module
Figure 4-1 Block diagram of control unit
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Signal acquisition
system
Display system