Mindray PM-9000 Express Service Manual
PM-9000 Express
Patient Monitor
Service Manual
Service Manual (V 1.0)
Copyright
Statement
SHENZHEN MINDRAY BIO-MEDICAL ELECTRONICS CO., LTD. (hereinafter called Mindray)
owns all rights to this unpublished work and intends to maintain this work as confidential.
Mindray may also seek to maintain this work as an unpublished copyright. This publication is to
be used solely for the purposes of reference, operation, maintenance, or repair of Mindray
equipment. No part of this can be disseminated for other purposes.
In the event of inadvertent or deliberate publication, Mindray intends to enforce its rights to this
work under copyright laws as a published work. Those having access to this work may not
copy, use, or disclose the information in this work unless expressly authorized by Mindray to
do so.
All information contained in this publication is believed to be correct. Mindray shall not be liable
for errors contained herein nor for incidental or consequential damages in connection with the
furnishing, performance, or use of this material. This publication may refer to information and
protected by copyrights or patents and does not convey any license under the patent rights of
Mindray, nor the rights of others. Mindray does not assume any liability arising out of any
infringements of patents or other rights of third parties.
Content of this manual is subject to changes without prior notice.
PROPERTY OF SHENZHEN MINDRAY BIO-MEDICAL ELECTRONICS CO., LTD.
ALL RIGHTS RESERVED
Responsibility on the manufacturer party
Mindray is responsible for safety, reliability and performance of this equipment only in the
condition that:
• all installation, expansion, change, modification and repair of this equipment are conducted
by Mindray qualified personnel;
• applied electrical appliance is in compliance with relevant National Standards;
• the monitor is operated under strict observance of this manual.
Warning
For continued safe use of this equipment, it is necessary that the listed instructions are
followed. However, instructions listed in this manual in no way supersede established medical
practices concerning patient care.
Do not rely only on audible alarm system to monitor patient. When monitoring
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Service Manual (V 1.0)
adjusting the volume to very low or completely muting the sound may result in the
disaster to the patient. The most reliable way of monitoring the patient is at the
same time of using monitoring equipment correctly, manual monitoring should be
carried out.
This multi-parameter patient monitor is intended for use only by medical
professionals in health care institutions.
To avoid electrical shock, you shall not open any cover by yourself. Service must be
carried out by qualified personnel.
Use of this device may affect ultrasonic imaging system in the presence of the
interfering signal on the screen of ultrasonic imaging system. Keep the distance
between the monitor and the ultrasonic imaging system as far as possible.
It is dangerous to expose electrical contact or applicant coupler to normal saline,
other liquid or conductive adhesive. Electrical contact and coupler such as cable
connector, power supply and parameter module socket-inlet and frame must be
kept clean and dry. Once being polluted by liquid, they must be thoroughly dried. If
to further remove the pollution, please contact your biomedical department or
Mindray.
It is important for the hospital or organization that employs this equipment to carry out a
reasonable maintenance schedule. Neglect of this may result in machine breakdown or injury
of human health.
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Service Manual (V 1.0)
Warranty
THIS WARRANTY IS EXCLUSIVE AND IS IN LIEU OF ALL OTHER WARRANTIES,
EXPRESSED OR IMPLIED, INCLUDING WARRANTIES OF MERCHANT ABILITY OR
FITNESS FOR ANY PARTICULAR PURPOSE.
Exemptions
Mindray's obligation or liability under this warranty does not include any transportation or other
charges or liability for direct, indirect or consequential damages or delay resulting from the
improper use or application of the product or the substitution upon it of parts or accessories not
approved by Mindray or repaired by anyone other than a Mindray authorized representative.
This warranty shall not extend to any instrument which has been subjected to misuse,
negligence or accident; any instrument from which Mindray's original serial number tag or
product identification markings have been altered or removed, or any product of any other
manufacturer.
Safety, Reliability and Performance
Mindray is not responsible for the effects on safety, reliability and performance of the
PM-9000 Express Patient Monitor if:
■ assembly operations, extensions, re-adjusts, modifications or repairs are carried out
by persons other than those authorized by Mindray.
■ the PM-9000 is not used in accordance with the instructions for use, or the electrical
installation of the relevant room does not comply with NFPA 70: National Electric
Code or NFPA 99: Standard for Health Care Facilities (Outside the United States, the
relevant room must comply with all electrical installation regulations mandated by the
local and regional bodies of government).
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Service Manual (V 1.0)
Return Policy
Return Procedure
In the event that it becomes necessary to return a unit to Mindray, the following procedure
should be followed:
1. Obtain return authorization. Contact the Mindray Service Department and obtain a
Customer Service Authorization (Mindray) number. The Mindray number must appear on
the outside of the shipping container. Return shipments will not be accepted if the Mindray
number is not clearly visible. Please provide the model number, serial number, and a brief
description of the reason for return.
2. Freight policy. The customer is responsible for freight charges when equipment is shipped
to Mindray for service (this includes customs charges).
Company Contact
Manufacture: Shenzhen Mindray Bio-Medical Electronics Co., Ltd.
Address:
Phone:
Fax:
Mindray Building, Keji 12th Road South, Hi-tech Industrial
Park, Nanshan, Shenzhen, P.R.China,518057
+86 755 26582479 26582888
+86 755 26582500 26582501
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Service Manual (V 1.0)
Safety Precautions
1. Meaning of Signal Words
In this manual, the signal words DANGER, WARNING, and CAUTION are used
regarding safety and other important instructions. The signal words and their meanings are
defined as follows. Please understand their meanings clearly before reading this manual.
Signal word Meaning
DANGER
WARNING
CAUTION
Indicates an imminently hazardous situation which, if not
avoided, will result in death or serious injury .
Indicates a potentially hazardous situation which, if not avoided,
could result in death or serious injury.
Indicates a potentially hazardous situation which, if not avoided,
may result in minor or moderate injury.
2. Meaning of Safety Symbols
Symbol Description
Type-BF applied part
"Attention" (Refer to the operation manual.)
Safety Precautions
Please observe the following precautions to ensure the safety of service engineers as well as
operators when using this system.
DANGER: Do not use flammable gases such as anesthetics, or flammable
liquids such as ethanol, near this product, because there is danger of
explosion.
WARNING: Do not connect this system to outlets with the same circuit
breakers and fuses that control current to devices such as
life-support systems. If this system malfunctions and
generates an over current, or when there is an instantaneous
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Service Manual (V 1.0)
current at power ON, the circuit breakers and fuses of the
building’s supply circuit may be tripped.
CAUTION: 1. Malfunctions due to radio waves
(1) Use of radio-wave-emitting devices in the proximity of this kind
of medical electronic system may interfere with its operation.
Do not bring or use devices which generate radio waves, such
as cellular telephones, transceivers, and radio controlled toys,
in the room where the system is installed.
(2) If a user brings a device which generates radio waves near the
system, they must be instructed to immediately turn OFF the
device. This is necessary to ensure the proper operation of
the system.
2. Do not allow fluids such as water to contact the system or
peripheral devices. Electric shock may result.
VI
Symbols
Service Manual (V 1.0)
displaying this symbol contains an F-Type isolated (floating) patient applied part providing
a high degree of protection against shock, and is suitable for use during defibrillation.
Equipotential grounding terminal CE mark 93/42/EEC a directive
of the European Economic
Community
@ Mark Event 》 Next menu
*** Highest level alarm ** Middle level alarm
* Lowest level alarm
Trend graph cursor u SYS pressure（NIBP trend graph）
t DIA pressure(NIBP trend graph) * MEAN pressure (NIBP trend
graph)
Right moving indicator Left moving indicator
Be Careful Protective earth ground
Indicates that the instrument is IEC-60601-1 Type CF equipment. The unit
Silence Symbol ！ Close all alarm volume
Alarm pause
Heart beat
× Gain magnify √ Confirm
SN Series Number
VII
Pace signal
Service Manual (V 1.0)
Contents
CHAPTER 1 ABOUT THE PRODUCT ...........................................................................................1
1.1 INTRODUCTION ........................................................................................................................ 1
1.2 APPLICATION............................................................................................................................ 1
1.3 ENVIRONMENT .........................................................................................................................3
CHAPTER 2 PRINCIPLES................................................................................................................4
2.1 GENERAL.................................................................................................................................. 4
2.2 HARDWARE DESCRIPTION.........................................................................................................5
2.3 SOFTWARE DESCRIPTION ........................................................................................................17
2.4 SYSTEM PARAMETER ..............................................................................................................19
CHAPTER 3 PRODUCT SPECIFICATIONS................................................................................25
3.1 SAFETY CLASSIFICATIONS .......................................................................................................25
3.2 ENVIRONMENTAL SPECIFICATIONS........................................................................................... 26
3.3 POWER SOURCE SPECIFICATIONS.............................................................................................27
3.4 HARDWARE SPECIFICATIONS....................................................................................................28
3.5 WIRELESS NETWORK ...............................................................................................................29
3.6 DATA STORAGE........................................................................................................................ 30
3.7 SIGNAL OUTPUT SPECIFICATIONS ...........................................................................................31
3.8 ECG SPECIFICATIONS .............................................................................................................32
3.9 RESP SPECIFICATIONS............................................................................................................. 34
3.10 SPO
3.11 IBP SPECIFICATIONS............................................................................................................... 37
3.12 TEMP SPECIFICATIONS........................................................................................................... 38
3.13 IBP SPECIFICATIONS................................................................................................................39
3.14 CO SPECIFICATIONS................................................................................................................ 40
3.15 CO
3.16 AG SPECIFICATIONS................................................................................................................44
SPECIFICATIONS .............................................................................................................35
2
SPECIFICATIONS............................................................................................................... 41
2
CHAPTER 4 DISASSEMBLING/ASSEMBLING & TROUBLESHOOTING..............................47
4.1 PM-9000 EXPRESS DISASSEMBLING/ASSEMBLING ................................................................ 47
4.2 TROUBLESHOOTING...............................................................................................................52
CHAPTER 5 TEST AND MATERIAL LIST...................................................................................55
5.1 TEST PROCEDURE ................................................................................................................. 55
5.2 NIBP CALIBRATION................................................................................................................59
5.3 IBP CALIBRATE.................................................................................................................. 59
5.4 CO2 CHECK......................................................................................................................... 62
5.5 AG CALIBRATE.................................................................................................................. 63
5.6 PM-9000 EXPRESS MATE R I A L LIST........................................................................................65
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CHAPTER 6 MAINTENANCE AND CLEANING..........................................................................66
6.1 MAINTENANCE .......................................................................................................................66
6.2 CLEANING ..............................................................................................................................66
6.3 CLEANING REAGENT ..............................................................................................................66
6.4 STERILIZATION ....................................................................................................................... 67
6.5 DISINFECTION......................................................................................................................... 67
II
Chapter 1 About the Product
Chapter 1 About the Product
1.1 Introduction
The PM-9000 Express Patient Monitor, a portable and accessible patient monitor, is supplied
by rechargeable batteries or external AC power, which applies to adults, pediatric and
neonates. You can select different configurations as required. Besides, the PM-9000 Express
can be connected with the central monitoring system whereby a monitoring network will be
formed. Parameters that the PM-9000 Express can monitor include: ECG, RESP, SpO
2-channel TEMP, 2-channel IBP, CO and CO
measurement, waveform monitoring, freezing and recording, is a compact and lightweight
patient monitor. Its color TFT LCD is able to show patient parameters and 8 waveforms clearly.
The compact control panel and knob control, and the easy-to-use menu system enable you to
freeze, record, or perform other operations conveniently.
The PM-9000 Express Patient Monitor measures patient’s ECG, NIBP, SpO
IBP, CO and CO
temperature sensor and pressure transducer. During the measurement, the patient monitor
does not get energy or any substance from the human body, and does not release any
substance to the human body. However, it releases sine wave signals to the patient when
measuring the respiration rate. The patient monitor converts the measured physiological
signals to the digital signals, waveforms and values, and then displays them on the screen.
You can control the patient monitor through the control panel. For example, you can set
different alarm limits for different patients. Thus, when the patient monitor detects any
physiological parameter exceeding the preset alarm limit, it will enable the audio and visual
alarm.
physiological signals through the ECG electrode, SpO2 sensor, cuff,
2
. It, integrating the functions of parameter
2
, TEMP, RESP,
2
, NIBP,
2
1.2 Application
1.2.1 General
In the treatment processes, it is necessary to monitor important physiological information of
patients. Therefore, the patient monitor has been playing an outstanding role among medical
devices. The development of technology does not only help medical staff get the important
physiological information, but also simplifies the procedures and makes it more effective. For
patients in hospital, the basic and important physiological information is required, including
ECG, SpO
technology helping measure and get important physiological information of patients has made
the patient monitor more comprehensive in performance and better in quality. Today,
multi-parameter patient monitors are widely used.
1.2.2 Usage
Parameters that the PM-9000 Express can monitor include: ECG, RESP, SpO2, NIBP, TEMP,
IBP, CO AGand CO
, RESP, IBP, CO, CO2, TEMP, etc. In recent years, the development of science and
2
. PM-9000 Express converts these physiological signals to digital signals,
2
1
Chapter 1 About the Product
processes them and displays them on the screen. You can set the alarm limit as required.
When the monitored parameter exceeds the preset alarm limit, the patient monitor will start the
alarm function. In addition, you can control the patient monitor through the control panel.
Usually, patient monitors are seen in some clinical areas in hospital, such as ICU, CCU,
intensive care units for heart disease patients, operating rooms, emergency departments and
observation wards. They can also be used in clinics. The PM-9000 Express patient monitor
should be run under the control of clinical staff.
PM-9000 Express patient monitor has the following functions:
ECG
Heart Rate (HR)
2-channel ECG waveform
Arrhythmia analysis and S-T analysis (optional)
Respiration Rate (RR) RESP
Respiration waveform
2
Pulse Oxygen Saturation(SpO
), Pulse Rate (PR) SpO
2
SpO2 Plethysmogram
NIBP Systolic pressure (NS), diastolic pressure (ND), mean pressure
(NM)
TEMP T1, T2, TD
IBP CH1: SYS, DIA
CH2: SYS, DIA
IBP waveform
CO Temperature of blood (TB)
Cardiac Output (CO)
CO
2
End-tidal carbon dioxide (EtCO2)
Inspired minimum CO
(InsCO2)
2
Airway Respiration Rate (AwRR)
AG
Inhaled and exhaled CO
Inhaled and exhaled N
Inhaled and exhaled O
(FiCO2, EtCO2)
2
O (FiN2O, EtN2O)
2
(FiO2, EtO2)
2
Inhaled and exhaled anesthetic agent (FiAA, EtAA, where AA
refers to any of the following anesthetic agents.)
HAL (Halothane)
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Chapter 1 About the Product
ISO (Isoflurane)
ENF (Enflurane)
SEV (Sevoflurane)
DES (desflurane)
Airway Respiration Rate (rpm: Respiration Per Minute): AwRR
Minimum Alveolar Concentration (MAC)
4 AG waveforms (CO
, N2O, O2, AA)
2
The PM-9000 Express provides the functions of audio/visual alarm, trend graphic storage and
output, NIBP measurement, alarm event identification, large font screen, defibrillator
synchronization, oxyCRG recall, drug calculation, etc.
1.3 Environment
1.3.1 Temperature
Work mode 0 – 40℃
MINDRAY CO
Welch Allyn mainstream CO
Microstream CO
Artema AION AG module +10 – +35℃
Transportation & Storage -20 – 60℃
1.3.2 Humidity
Work mode 15% – 95 % (non-condensing)
Transportation & Storage 10% – 95 % (non-condensing)
Atmospheric pressure 70.0kPa – 106.0kPa
module +5 – +35℃
2
module +10 – +40℃
2
module +5 – +35℃
2
1.3.3 Electrical specification
100 – 240 V AC, 50/60 Hz,
Maximum input power: 140VA; fuse: T 3A
2.3 Ah 12V lead-acid rechargeable battery
Working time of fully-charged batteries in normal status: 120 minutes (2 batteries).
From the first low-battery alarm, the batteries can supply power to the patient monitor for 5
more minutes.
Maximum charging time: ≤12h
4.4Ah 11.1V lithium battery
Working time of fully-charged batteries in normal status: 300 minutes (2 batteries).
From the first low-battery alarm, the batteries can supply power to the patient monitor for 5
more minutes.
Maximum charging time: ≤ 6.5h
3
Chapter 2 Principles
Chapter 2 Principles
2.1 General
The intended use of the PM-9000 patient monitor is to monitor a fixed set of parameters
including ECG, RESP, SpO
consists of the following functional parts:
Parameter measurement;
Main control part;
Man-machine interface;
Power supply;
Other auxiliary functions;
These functional units are respectively detailed below.
, NIBP, TEMP, IBP, CO and CO2 (IBP, CO and CO2 are optional). It
2
Figure 2-1 Structure of the PM-9000 Express
2.1.1 Parameter Measurement
The parameter measurement and monitoring are the core functions of the patient monitor. The
4
Chapter 2 Principles
parameter measurement part of the PM-9000 Express patient monitor consists of the
measurement probe, parameter input socket assembly, NIBP assembly and the main control
board.
This part converts the physiological signals to electric signals, processes the those signals and
conducts the calculation by the preset program or command delivered from the main control
board, and then sends the values, waveforms and alarm information (which will be displayed
by using the man-machine interface) to the main control board.
2.1.2 Main Control Part
In the PM-9000 Express patient monitor, the main control part refers to the main control part of
the main control board. It drives the man-machine interface, manages the parameter
measurement and provides users with other special functions, such as storage, recall of
waveforms and data. (See Figure 2-1)
2.1.3 Man-Machine Interface
The man-machine interface of the PM-9000 Express patient monitor includes the TFT display,
recorder, speaker, indicator, buttons and control knob.
The TFT display is the main output interface. It, with the high resolution, provides users with
abundant real-time and history data and waveforms as well as various information and alarm
information.
The recorder is a subsidiary of the display, which is used for the user to print data.
The speaker provides the auditory alarm function.
The indicator provides additional information about the power supply, batteries, alarms and so
on.
The buttons and control knob are the input interface, which are used for the user to input the
information and commands to the patient monitor.
2.1.4 Power Supply
The power supply part is an important part of the patient monitor. It includes the main power
PCB, backlight board, batteries and fan.
The main power PCB converts the external AC current respectively to the 5V DC and 12V DC
current, which are supplied for the whole system. For the TFT display, there is a special
requirement on the power supply, so a backlight board is used. The batteries supply power for
the system for a short time when there is no external AC current. The fan is used for the heat
sink of the system.
2.1.5 Other Auxiliary Functions
The PM-9000 Express patient monitor also provides the network upgrade function for the
service engineers to upgrade the system software without disassembling the enclosure.
2.2 Hardware Description
The structure of the PM-9000 Express patient monitor is shown in the following figure.
5
Chapter 2 Principles
Figure 2-2 Functional structure of the PM-9000 Express
6
Chapter 2 Principles
The PM-9000 Express PCB connection is shown in the following figure.
Figure 2-3 PCB connection
Basic functions and working principles of modules are described in the following sections.
2.2.1 Main Board
2.2.1.1 General
The main board is the heart of the patient monitor. It implements a series of tasks, including the
system control, system scheduling, system management, data processing, file management,
display processing, printing management, data storage, system diagnosis and alarm.
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Chapter 2 Principles
2.2.1.2 Principle diagram
Figure 2-4 Working principle of the main board
2.2.1.3 Principle
The main board is connected with external ports, including the power input port, multi-way
serial port, TFT display interface, analog VGA interface, network port and analog output port.
Besides, on the main board is also a BDM interface reserved for the software debugging and
software downloading.
CPU System
CPU is the core part of the main board. It, connected with other peripheral modules
through the bus and I/O cable, implements the data communication, data processing,
logical control and other functions.
RTC
RTC provides the calendar information (such as second, minute, hour, day, month and
year). CPU can read and modify the calendar information from RTC.
Ethernet Controller
Ethernet Controller supports the IEEE802.3/IEEE802.3u LAN standard, and supports two
data transmission rate: 10Mbps and 100Mbps. CPU exchanges data with the Ethernet
through the Ethernet Controller.
Analog Output
The D/A converter converts the digital ECG/IBP signals sent from CPU to the analog
signals, which are provided for the external after low-pass filtered by the filter and
amplified by the amplifier.
FPGA and VRAM
VRAM stores the displayed data. CPU stores the displayed data to VRAM through FPGA.
FPGA gets data from VRAM, processes them, and then sends them to the relevant
graphic display device.
8
Chapter 2 Principles
In addition, FPGA also extends multiple serial ports, which communicate with peripheral
modules. FPGA transfers the received data to CPU through the bus; CPU delivers data to
FPGA through the bus, and then the FPGA transfers those data to the peripheral
modules.
Watchdog
When powered on, watchdog provides reset signals for CPU, FPGA and Ethernet
Controller.
The patient monitor provides the watchdog timer output and voltage detection functions.
2.2.2 ECG/RESP/TEMP Module
2.2.2.1 General
This module provides the function of measuring three parameters: electrocardiograph (ECG),
respiration (RESP) and temperature (TEMP).
2.2.2.2 Principle diagram
Figure 2-5 Working principle of the ECG/RESP/TEMP module
2.2.2.3 Principle
This module collects the ECG, RESP and TEMP signals through the transducer, processes the
signals, and sends the data to the main board through the serial port.
ECG Signal Input Circuit
The input protection and filtering circuits receive the ECG signal from the transducer, and filter
the high-frequency interference signal to protect the circuit against the damage by defibrillator
high-voltage and ESD.
The right-leg drive circuit gets the 50/60Hz power common-mode signal from the lead cable,
and sends the negative feedback signal to the human body to reject the common-mode
interference signal on the lead cable, which helps the detection of the ECG signal.
The lead-off detecting circuit checks whether the ECG lead is off, and sends the information to
CPU.
ECG Signal Process Circuit
The difference amplifying circuit conducts the primary amplification of the ECG signal and
9
Chapter 2 Principles
rejects the common-mode interference signal.
The low-pas filtering circuit filters the high-frequency interference signal beyond the frequency
band of the ECG signal.
The PACE signal refers to the ECG pace signal. It has significant interference to the ECG
signal detection. The PACE rejection circuit can rejects the PACE signal, which helps the ECG
signal detection.
The main amplifying/filtering circuit conducts the secondary amplification of the ECG signal,
filters the signal, and then sends the ECG signal to the A/D conversion part.
Pace Detect
This part detects the PACE signal from the ECG signal and sends it to CPU.
Temperature Detect Circuit
This circuit receives the signal from the temperature transducer, amplifies and filters it, and
then sends it to the A/D conversion part.
Carrier Generate Circuit
The RESP measurement is based on the impedance method. While a man is breathing, the
action of the breast leads to changes of the thoracic impedance, which modulates the
amplitude of the high-frequency carrier signal. Finally, the modulated signal is sent to the
measurement circuit. The purpose of this module is generating the high-frequency carrier.
RESP Signal Input Circuit
This circuit couples the RESP signal to the detecting circuit.
RESP Signal Process Circuit
The pre-amplifying circuit conducts the primary amplification of the RESP signal and filters it.
The detecting circuit detects the RESP wave that has been modulated on the actuating signal.
The level shifting circuit removes the DC component from the RESP signal.
The main amplifying/filtering circuit conducts the secondary amplification of the RESP signal,
filters 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 the signal
to CPU for further processing.
CPU System
Implementing the logical control of all parameter parts and A/D conversion parts;
Implementing the data processing for all parameters;
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.
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Chapter 2 Principles
2.2.3 CO/IBP Module
2.2.3.1 General
This module provides the function of measuring two parameters: Cardiac Output (CO) and
Invasive Blood Pressure (IBP).
2.2.3.2 Principle diagram
Figure 2-6 Working principle of the CO/IBP module
2.2.3.3 Principle
This module collects the CO/IBP signal through the transducers, processes it and sends it
to the main board throgh the serial port.
CO Signal Process Network
The CO parameter is measured with the thermal dilution method. The transducer
sends two signals (TI: Temperature of Injectate; TB: Temperature of Blood) to the CO
Signal Process Network. After that, the signals are amplified and low-pass filtered, and
then sent to the CPU System for processing.
IBP Signal Process Network
The IBP signal is the differential signal. After the common-mode filtering, the difference
signal is amplified by the difference amplifying circuit which changes the dual-end signal
to the single-end signal. After the low-pass filtering, the IBP signal is sent to the CPU
System for processing.
CPU System
Converting the analog signal obtained by the circuit to the digital signal;
Implementing the logical control of all parameter parts;
Implementing the data processing for the two parameters;
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.
11
Chapter 2 Principles
2.2.4 SpO2 Module
2.2.4.1 General
This module provides the function of measuring the Pulse Oxygen Saturation (SPO2).
2.2.4.2 Principle diagram
Figure2-7 Working principle of the SpO2 module
2.2.4.3 Principle
The SpO
measurement principle
2
1. Collecting the light signal of the red light and infrared transmitting through the finger
or toe which is pulsing;
2. Processing the collected signal to get the measured result.
The drive circuit of the LED and the gain of the amplifying circuit should be controlled
according to the different perfusions and transmittances of the tested object.
Led Drive Circuit
This circuit supplies the LED with the drive current, which can be regulated.
SPO2 Signal Process Network
The pre-amplifying circuit converts the photoelectric signal to the voltage signal and conducts
the primary amplification.
The gain adjusting and amplifying circuit conducts the secondary signal amplification and
adjusts the gain.
The biasing circuit adjusts the dynamic range of the signal, and sends it to the A/D conversion
part.
A/D
The A/D conversion part converts the analog signal to the digital signal, and then sends it to
CPU for further processing.
D/A
The D/A conversion part converts the digital signal received from CPU to the analog signal,
and provides the control signal for the Led Drive Circuit and SPO2 Signal Process Network.
CPU System
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