Respironics BiPAP Vision Service manual
Service
Manual
The BiPAP Vision Ventilatory Support System is the subject of U.S. patents #5148802,
#5239995, #5313937, #5433193, and other pending U.S. and foreign patents. BiPAP is a registered trademark of Respironics.
Copyright © 1998-2007 Respironics. All rights reserved.
BiPAP Vision Service Manual
1045049
Limited Warranty
Respironics warrants that the BiPAP® VisionTM Ventilatory Support System (BiPAP Vision) shall be free from defects
of workmanship and materials and will perform in accordance with the product specifications for a period of one year
from the date of sale by Respironics. If the product fails to perform in accordance with the product specifications,
Respironics will repair or replace—at its option—the defective material or part. Respironics will pay customary
freight charges from Respironics to the dealer location only. This warranty does not cover damage caused by
accident, misuse, abuse, alteration, and other defects not related to materials or workmanship.
Respironics disclaims all liability for economic loss, loss of profits, overhead or consequential damages which may
be claimed to arise from any sale or use of this product. Some states do not allow the exclusion or limitation of
incidental or consequential damages, so the above limitation or exclusion may not apply to you.
This warranty is given in lieu of all other express warranties. In addition, any implied warranty, including any
warranty of merchantability or fitness for the particular purpose, is limited to one year. Some states do not allow
limitations on how long an implied warranty lasts, so the above limitation may not apply to you. This warranty gives
you specific legal rights, and you may also have other rights which vary from state to state.
The warranty for repairs is 90 days for labor and one year on the part(s) that was replaced.
To exercise your right under this warranty, contact your local authorized Respironics dealer or contact Respironics
at:
1045049
Visit Respironics Home Page on the World Wide Web at:
http://www.respironics.com
BiPAP Vision Service Manual
Table of Contents
Chapter 1: Introduction .......................................................................................1-1
1.1 BiPAP Vision Ventilatory Support System Overview .............................................. 1-2
1.2 Service Notice ................................................................................................................. 1-3
1.3 Technical Support .......................................................................................................... 1-3
Chapter 2: Warnings, Cautions, and Notes ....................................................2-1
2.1 Warnings.......................................................................................................................... 2-2
2.2 Cautions........................................................................................................................... 2-3
2.3 Notes ................................................................................................................................ 2-4
Chapter 3: Description and Theory of Operation ........................................3-1
3.1 BiPAP Vision System ..................................................................................................... 3-2
3.2 Power Supply Subsystem (PSS) ................................................................................... 3-6
3.3 Main Control (MC) ........................................................................................................3-8
3.4 Pressure Control (PC) ....................................................................................................3-9
3.5 Display Control (DC) ................................................................................................... 3-11
3.6 Airflow Module (AFM) ............................................................................................... 3-14
3.7 Oxygen Module (OM) ................................................................................................. 3-16
3.8 Description of Ventilator Modes................................................................................ 3-17
3.9 Nurse Call / Remote Alarm ....................................................................................... 3-19
3.10 Patient Disconnect Alarm Description ...................................................................... 3-21
Chapter 4: Specifications and Control Ranges..............................................4-1
4.1 Specifications .................................................................................................................. 4-2
4.2 Control Ranges and Increments ................................................................................... 4-5
Chapter 5: Routine Maintenance......................................................................5-1
5.1 Cleaning........................................................................................................................... 5-2
5.2 Replacing the Inlet Filter............................................................................................... 5-3
5.3 Cleaning / Replacing the Nylon Mesh Inlet Filter ................................................... 5-4
5.4 Replacing the Oxygen Regulator Filter ...................................................................... 5-6
5.5 Changing the System Fuses ..........................................................................................5-8
5.6 Voltage and Fuse Selection ......................................................................................... 5-10
5.7 Power Cord Inspection................................................................................................5-10
5.8 Internal Alarm Battery ................................................................................................. 5-11
5.9 Preventive Maintenance Schedule ............................................................................ 5-14
Chapter 6: Troubleshooting ................................................................................6-1
6.1 Overview......................................................................................................................... 6-2
6.2 Description of System Alarms......................................................................................6-5
6.3 Alarm Indicators............................................................................................................6-7
6.4 Troubleshooting ............................................................................................................. 6-8
6.5 Error Codes ................................................................................................................... 6-12
6.6 Vent Inop Errors ........................................................................................................... 6-14
i
Chapter 7: Repair and Replacement ................................................................7-1
7.1 Contact Information ....................................................................................................... 7-2
7.2 Exploded View...............................................................................................................7-3
7.3 BiPAP Vision Repair Kits ............................................................................................. 7-5
7.4 Mobile Stand II & III Repair Parts..............................................................................7-10
7.5 Replacement Identification Photos ........................................................................... 7-11
7.6 Touch Pad Replacement Instructions ........................................................................ 7-59
Chapter 8: Testing and Calibration ..................................................................8-1
8.1 Overview ........................................................................................................................... 8-2
8.2 Recommended Testing after Part(s) Replacement .................................................... 8-3
8.3 Exhalation Port Test ....................................................................................................... 8-5
8.4 Total Operating Hours Transfer Procedure ............................................................... 8-8
8.5 Blower / Valve Calibration Procedure..................................................................... 8-10
8.6 Performance Verification............................................................................................. 8-12
8.7 Run-In Cycle Procedure .............................................................................................. 8-16
8.8 System Final Test.......................................................................................................... 8-18
8.9 PC/Laptop Set-up Procedure ....................................................................................8-37
8.10 Test Cable Usage Definitions ..................................................................................... 8-40
8.11 Oxygen Flow Module Test ......................................................................................... 8-41
Chapter 9: Option Instructions ..........................................................................9-1
9.1 PAV/T Mode Installation or EPROM Upgrade ........................................................ 9-2
9.2 Oxygen Baffle Installation Instructions .......................................................................9-6
Chapter 10: Summary of Upgrades for Repairs of Vision units with Serial
Numbers 100500 to 106000......................................................... 10-1
10.1 Summary of upgrades for repairs of Vision units w/ serial numbers
100500 to 106000...........................................................................................................10-2
10.2 Repair Kits No Longer Manufactured ..................................................................... 10-5
10.3 Installation/Upgrade Instructions for Repair Parts ............................................... 10-6
Appendix A: Tools and Equipment................................................................ A-1
A.1 Service Tools and Supplies.......................................................................................... A-2
A.2 Acceptable Test Equipment......................................................................................... A-3
A.3 TSI, Inc. Certifier Test System ..................................................................................A-6
Appendix B: Schematics .................................................................................... B-1
B.1 Schematic Statement .................................................................................................... B-2
B.2 Main Control (MC) ...................................................................................................... B-3
B.3 Display Control (DC) .................................................................................................. B-9
B.4 Pressure Control (PC) ................................................................................................ B-20
B.5 Air Flow Module (AFM) ............................................................................................ B-25
B.6 Oxygen Module (OM) ................................................................................................ B-26
B.7 Power Supply ............................................................................................................. B-27
ii
Chapter 1: Introduction
1-1
Chapter 1: Introduction
1.1 BiPAP Vision Ventilatory Support System Overview ..........1-2
1.2 Service Notice.............................................................................. 1-3
1.3 Technical Support ....................................................................... 1-3
Chp. 1
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1-2
Chapter 1: Introduction
Chapter 1: Introduction
®
1.1 BiPAP
The BiPAP Vision Ventilatory Support System (BiPAP Vision), shown in Figure 1-1, is a microprocessor-controlled, positive pressure ventilatory assist system. The BiPAP Vision incorporates a user interface with multifunction keys, real time graphic displays, and integral patient and system alarms.
The BiPAP Vision features a centrifugal blower to generate airflow, as well as hardware and software platforms
that can be upgraded with an oxygen module and additional patient alarms. The system operates in the Continuous Positive Airway Pressure (CPAP), Pressure Support (S/T), and optional Proportional Assist Ventilation/Timed (PAV/T) modes.
The BiPAP Vision contains a variety of integrated safety and self-diagnostic features. All system functions are
checked at start-up and during operation. Errors are reported by visual and/or audible indicators.
Pressure regulation is achieved by monitoring proximal airway pressure and adjusting flows accordingly to
ensure that the proximal pressure equals the set pressure.
Vision™ Ventilatory Support System Overview
EPAP
6
cm H
O
2
Rate
12
BPM
V
T
1000
IPAP
15
MODE: S/T MONITORING
cm H
O
2
P (cm H
Vol (ml)
Flow (L/min)
ml
MinVent
O)
2
PS = 9
%O
2
cm H
2
O
55
%
14
L/min
PIP
15
cm H
O
2
Options
Figure 1-1
The BiPAP Vision Ventilator
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BiPAP Vision Service Manual
Chapter 1: Introduction
1-3
1.2 Service Notice
This service manual was prepared by Respironics primarily for use by qualified technicians
required to service the BiPAP Vision.
1.3 Technical Support
Respironics is committed to customer satisfaction, and may be contacted with any questions or for technical
support at the following numbers:
U.S. and Canada
Phone: 1-800-345-6443
Fax: 1-800-866-0245
International
Phone: 1-724-387-4000
Fax: 1-724-387-5012
Chp. 1
E-Mail service@respironics.com
Visit Respironics Home Page on the World Wide Web at:
http://www.respironics.com
BiPAP Vision Service Manual
1045049
Chapter 2: Warnings, Cautions, and Notes
Chapter 2: Warnings, Cautions, and
Notes
2.1 Warnings ........................................................................................ 2-2
2.2 Cautions ......................................................................................... 2-3
2. 3 Notes ..............................................................................................2-4
2-1
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2-2
Chapter 2: Warnings, Cautions, and Notes
Chapter 2: Warnings, Cautions, and Notes
WARNING: Indicates the possibility of injury.
CAUTION: Indicates the possibility of damage to the device.
NOTE: Places emphasis on an operating or procedural characteristic.
2.1 WARNINGS
2.1.1 Safety
• Do not use the BiPAP Vision in the presence of a flammable anesthetic mixture with
air, oxygen, or nitrous oxide.
• Oxygen supports combustion. Do not use oxygen while smoking or in the presence of
an open flame.
• When using the optional oxygen module, the BiPAP Vision does not provide an oxygen
sensor to monitor oxygen concentrations delivered to the patient circuit. Therefore, the
use of oxygen with the BiPAP Vision should be monitored through oximetry.
NOTE: Refer to the Clinical Manual for guidelines on Applications and Operation.
2.1.2 Operational
• If the “Ventilator Inoperable” indicator illuminates, refer to Chapter 6 of this manual for
troubleshooting guidelines.
• Never attach oxygen tubing or any positive pressure source to the pressure port on the
front panel of the BiPAP Vision.
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BiPAP Vision Service Manual
Chapter 2: Warnings, Cautions, and Notes
Warnings (Continued)
2.1.3 Service
CAUTION: Electronic components used in this device are subject to damage from static
electricity. Repairs made to this device must be performed only in an antistatic,
ESD-protected environment.
• Do not attempt to make connection to the diagnostic RS232 connector on the back panel of
the BiPAP Vision to obtain repair information while the unit is operating on a patient.
• To assure the safety of the service technician and specified performance of the device,
Respironics recommends that only qualified technicians perform repairs to the BiPAP
Vision. Contact Respironics Technical Service for service training and authorization
information.
• High voltages are present inside this device. To avoid electrical shock, disconnect the
electrical supply before attempting any repairs on the device.
• For continued protection against risk of fire, replace fuses with those of the same type
and rating only.
2-3
2.1.4 Cleaning
• To avoid electrical shock, unplug the BiPAP Vision unit before cleaning it.
2.2 CAUTIONS
• While cleaning the unit, do not allow any liquid to enter the cabinet or the inlet filter.
• Care should be taken to avoid exposing the BiPAP Vision to operating, storage, and
transport temperatures near the extremes specified in Chapter 4. If exposed to such
temperatures, allow the unit to cool or warm to room temperature before turning it on.
• The unit must be positioned on its base for proper operation.
• Always use an inlet filter when the BiPAP Vision is in use.
• If using the oxygen module, do not exceed 100 psig oxygen supply pressure.
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2-4
Chapter 2: Warnings, Cautions, and Notes
2.3 NOTES
• This device contains a rechargeable nickel-cadmium (NiCAD) battery which is used by
the alarms in the event of a power failure.
• Refer to the BiPAP Vision Clinical Manual for a complete list of operational Warnings,
Cautions, and Notes.
Additional WARNINGS, CAUTIONS, and NOTES are located throughout this manual.
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BiPAP Vision Service Manual
Chapter 3: Description and Theory of Operation
Chapter 3: Description and Theory of
Operation
3.1 BiPAP Vision Ventilatory Support System ............................... 3-2
3.2 Power Supply Subsystem (PSS) ................................................ 3-6
3.3 Main Control (MC)...................................................................... 3-8
3.4 Pressure Control (PC) ................................................................. 3-9
3.5 Display Control (DC)................................................................ 3-11
3-1
3.6 Airflow Module (AFM) ............................................................ 3-14
3.7 Oxygen Module (OM) .............................................................. 3-16
3.8 Description of Ventilator Modes ............................................. 3-17
3.9 Nurse Call / Remote Alarm .................................................... 3-19
3.10 Patient Disconnect Alarm ........................................................ 3-21
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3-2
Chapter 3: Description and Theory of Operation
Chapter 3: Description and Theory of Operation
3.1 BiPAP Vision Ventilatory Support System
The BiPAP Vision is a microprocessor-controlled, positive pressure ventilatory assist system. The
system’s integral air intake filter draws in ambient air which is then pressurized by the system’s centrifugal blower assembly. The In-Line Flow Restrictor (ILFR) valve and Pressure Regulation Valve (PRV),
which are both located in the blower discharge airway, regulate total flow and pressure at the blower
discharge system. An oxygen module can be installed to add a controlled source of supplemental oxygen,
up to 100%, to the patient.
The Pressure Control (PC) board continuously monitors the readings from the Airflow Module (AFM) of
total gas flow, temperature, generated pressure, and patient circuit pressure to ensure prescribed therapy
to the patient. The PC board transmits process data to the Main Control (MC) board which then provides
overall control of the BiPAP Vision, including conveying instructions to the PC board regarding required
valve stem position and blower speed.
The unique design and operation of the ventilator makes it especially suited for mask applications.
Designed with the BiPAP
conditions, the ventilator is capable of ensuring optimum patient-ventilator synchronicity despite changes
in breathing patterns and circuit leaks. (Refer to the BiPAP Vision Clinical Manual.)
A liquid crystal display (LCD) screen is mounted on the front enclosure of the BiPAP Vision. The LCD
and the Display Control (DC) board provide the primary user interface with the ventilator, including the
visual presentation of data, control features, and visual and audible presentation of alarm conditions. The
user interacts with the ventilator through the touch pad and rotation of the rotary encoder while observing the results of this input on the display. The information provided on the display varies depending on
the state of the ventilator and / or the operations being performed.
The BiPAP Vision incorporates a number of safety features and self-diagnostic systems. System internal
functions are checked automatically at start-up, and periodically throughout normal operation. An
audible and visual alarm announces failures of principal subsystems. Integrated patient alarms are also
provided and are announced on a visual message display area as well as with an audible tone.
The following sections of this chapter describe in more detail the major subsystems and components that
make up the BiPAP Vision and its basic theory of operation.
Auto-Trak Sensitivity
TM
feature that automatically adjusts to changing circuit
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BiPAP Vision Service Manual
Chapter 3: Description and Theory of Operation
BiPAP Vision Ventilatory Support System (Continued)
3-3
Subsystem
PSS The Power Supply Subsystem (PSS) provides DC power to the BiPAP Vision
from an AC source.
MC The Main Control (MC) board or Main Control Subsystem (MCS) performs all control,
or data acquisition, and calculations required for the user-selected parameters. In addition,
MCS the MC performs the start-up test and reports all errors.
PC The Pressure Control (PC) board or Pressure Airflow Subsystem (PAS) controls the blower
or and valves to generate and regulate the system pressure. The PAS senses the outlet
PAS pressure and the patient pressure and regulates the outlet pressure to the patient circuit.
DC Through the touch pad, the Display Control (DC) board or Display/Control
or Subsystem (D/CS) evaluates user inputs and passes valid parameters to the MC. The DC
D/CS receives display data from the MC. The DC also has its own internal functions; the
results of which are reported to the MC.
AFM The Airflow Module (AFM), including the mass airflow sensor in the airstream,
provides an airflow measurement interface to the PC, allowing the PC to
measure total flow, temperature, and system pressure.
Function
ILFR The In-Line Flow Restrictor (ILFR) valve assembly regulates the total flow
from the blower discharge.
PRV The Pressure Regulation Valve (PRV) assembly is opened during exhalation to
allow the patient flow to be exhausted.
OM The Oxygen Module (OM) subassembly regulates and proportions the oxygen released
into the air from the blower according to the oxygen concentration level set on the
parameters screen.
BiPAP Vision Service Manual
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3-4
*
*
Chapter 3: Description and Theory of Operation
BiPAP Vision Ventilatory Support System (Continued)
BiPAP Vision Block Diagram
Figure 3-1
BiPAP Vision Block Diagram
*
*
* For S/N 106001 and greater
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BiPAP Vision Service Manual
Chapter 3: Description and Theory of Operation
3-5
Pneumatics Block Diagram
BiPAP Vision Service Manual
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3-6
Chapter 3: Description and Theory of Operation
3.2 Power Supply Subsystem (PSS)
The PSS supplies the Main Control (MC), Pressure Control (PC), and the Display Control (DC) with the
proper DC supply voltage. Safety features designed into the circuitry include an overvoltage disconnect,
low voltage supply detect, and line loss detect. Other features include “power-on” indicator voltage,
circulation fan power, and an On/Off switch connection.
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Figure 3-2
PSS Block Diagram
BiPAP Vision Service Manual
Chapter 3: Description and Theory of Operation
Power Supply Subsystem (PSS) (Continued)
3.2.1 Input Range
The BiPAP Vision can operate with an AC input of 100, 120, 230, or 240 VAC (±10%) depending on the
model.
3.2.2 DC Supply
The output DC supply is fused at 30 amps and delivers between 20.6 VDC and 35 VDC with a maximum
ripple of 1 vpp (peak-to-peak voltage) to the MC, PC, and DC.
3.2.3 Overvoltage Disconnect
The overvoltage disconnect is used to remove the DC supply output when it exceeds 36 VDC and reconnects it when the level returns to an acceptable value.
3.2.4 AC Fail
The MC module monitors the level of DC supply voltage and the AC voltage output from the transformer
supply winding to determine if an AC fail condition exists.
3-7
Low DC supply detect – If the DC supply voltage drops to 19.38 VDC or lower (nominal), an AC fail
condition will be triggered.
Line loss detect – The AC voltage output from the transformer supply winding is monitored for a loss-ofcycle condition. Both legs of the winding are input to the monitoring circuitry. Whenever AC is lost, the
AC fail signal is activated.
3.2.5 Outputs
The PSS module also includes the following:
a. Front panel “power-on” indicator voltage (J5)
b. Circulation fan power (J4)
c. On / Off switch (part of J2)
d. Circulation fan current sense information to (J12) on the PC subsystem.
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3-8
Chapter 3: Description and Theory of Operation
3.3 Main Control Subsystem (MC)
The MC is microcontroller-based and provides overall system control and supervision by monitoring the
activity of all the other system modules and providing commands to these modules based on user and
system input. The MC also acts as the bus controller for all subsystem communications using the
Intermodule Communications Bus (ICB).
4
J6
Nurse Call /
Remote Alarm *
*
DCS RX / TX
J5
PAS RX / TX
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Figure 3-3
MC Block Diagram
* For S/N units >106K
BiPAP Vision Service Manual
Chapter 3: Description and Theory of Operation
3.4 Pressure Control Subsystem (PC)
The PC functions through a microcontroller to:
a. Communicate with the Main Controller Subsystem (MC)
b. Communicate to a terminal / PC for diagnostics
c. Acquire sensor data through an Analog-to-Digital Converters (ADC, A / D)
d. Control valves and the blower motor through a Digital-to-Analog Converter (DAC)
e. Respond to or invoke an error signal
3-9
or
J15*
*
* For Units Serial Number <106K
*
*
PC
*
Figure 3-4
PC Block Diagram
BiPAP Vision Service Manual
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3-10
Chapter 3: Description and Theory of Operation
Pressure Control Subsystem (PC) (Continued)
3.4.1 Microcontroller Interface
Programmable Array Logic (PAL) memory device decodes the chip selects in such a way that the program code is retrieved from the EEPROM and data is retrieved from the RAM. An additional PAL
provides the interface for the Intermodule Communications Bus (ICB). The microprocessor monitors:
oxygen and gas temperatures; Airflow Module (AFM) and Oxygen Module (OM) detection; In-Line Flow
Restrictor (ILFR), Pressure Regulation Valve (PRV), and oxygen valve DAC control voltage; blower DAC
control voltage; and power supply and reference voltages.
3.4.2 Blower Motor Drive
The complete motor controller includes closed loop speed control via analog circuitry. When the desired
speed and actual speed are known by the processor, the speed is adjusted by increasing or decreasing the
DAC converter output to achieve proper pressure and flow.
3.4.3 Pressure Regulation Valve (PRV) and In-Line Flow Restrictor
(ILFR) Drives
The valve drives have closed loop control via the microprocessor. The microprocessor reads seven
pressure, flow, and temperature sensors through the PC hardware, and receives prescription parameters
from the MC. The microprocessor then adjusts analog DAC voltages to control the PRV and ILFR valves
as required to meet the prescription.
3.4.4 Pressure Sensors
The PC module has two dual pressure sensors (MT1 and MT2) and a single sensor (MT3). They measure
patient pressure, unit outlet pressure, and barometric pressure. These sensors are subject to calibration
with their calculated slope and intercept values stored in the on-board EEPROM. MT3 is a backup outlet
pressure sensor that provides a redundant check of the primary outlet sensor located on the AFM.
NOTE: Calibration is factory programmed and field adjustment is not required.
3.4.5 Error Line Control (ELC) Circuit
The ELC circuit is designed to simply detect a failure from, or signal a failure to, the MC and Display
Control (DC) modules. If the ELC line activates, only a power On / Off of the ventilator can clear this
latched circuit state.
3.4.6 Diagnostics Connector
The diagnostic connector (J3) interfaces with the microprocessor to view PC functions and system errors
on units from serial number 100500 to 105999, unless upgraded. For units greater than this, the diagnostic connector is on the rear of the unit.
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BiPAP Vision Service Manual
Chapter 3: Description and Theory of Operation
3.5 Display Control Subsystem (DC)
The DC provides a means of displaying the operating mode, measured and calculated operating parameters, parameter setpoints, alarm limits, real-time graphics, and general status information. The DC also
provides the necessary user interface controls to modify the operating mode, parameter set points, alarm
limits, and graphical scales; and to reset or silence the audible alarm, and freeze or unfreeze graphics.
The displays and controls are described in more detail in the following subsections.
*
or
*
3-11
or
*
* For Units Serial Number < 106K
Figure 3-5
DC Block Diagram
BiPAP Vision Service Manual
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3-12
Chapter 3: Description and Theory of Operation
Display Control (DC) (Continued)
3.5.1 DC/DC Converter
The DC/DC converter reduces the +24 VDC bulk supply to a +5 VDC logic level. (S/N <106K)
3.5.2 Display Backlight and Contrast Adjustment
A serial 8-bit D/A converter provides two, 0 to +5 VDC which originate in the MCU for these controls.
3.5.3 Display Voltage DC/DC Converter
This adjustable negative voltage converter reduces the level of bulk supply voltage needed to operate the
Liquid Crystal Display (LCD) contrast control.
3.5.4 Cold Cathode Fluorescent Tube (CCFT) Inverter
The DC design has a DC to AC inverter that typically provides 390 VAC to the fluorescent tube in the
display through (J2). The current varies to adjust the brightness of the fluorescent tube.
3.5.5 Reference Voltage Checks
This circuit compares reference voltages to determine if they are at the appropriate level.
3.5.6 Power Failure Alarm Battery Enable
This control detects a power failure from the DC supply.
3.5.7 Alarm Battery Voltage Cutout/Check
The battery voltage cutout /check monitors the battery voltage level and cuts it out if it drops to a level of
approximately 3VDC.
3.5.8 Backup Battery/Charger
The DC contains a 3.6 V nickel cadmium rechargeable battery that operates the audible and visual alarm
indicators for at least 20 minutes, when fully charged, when the Error Line Control (ELC) is active, and
the DC supply has been removed. The battery output is compared to a reference voltage and the battery
is recharged as required through a charging circuit. If necessary, refer to page 5-12 to recharge the
battery.
3.5.9 Check Ventilator Light Emitting Diode (LED) Enable Current
Check
An internal test is performed to verify that the Check Ventilator LED current is acceptable.
3.5.10 Vent Inop LED Current Check
An internal test is performed to verify the Ventilator Inoperative LED current is acceptable.
3.5.11 Error Line Control (ELC) Circuits
The DC contains redundant error signaling circuitry to communicate error conditions among the subsystems. The circuitry’s redundant and diverse nature minimizes the chance of communication failures.
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BiPAP Vision Service Manual
Chapter 3: Description and Theory of Operation
Display / Control Subsystem (D / CS) (Continued)
3.5.12 Error LED
The error LED indicates that an error condition was detected, and it illuminates to make unit diagnosis
easier.
3.5.13 Diagnostic Interface
The diagnostic connector interface (J5) interfaces with the MCU to provide a means for the DC to download diagnostic data to a terminal or PC.
3.5.14 EEPROM
A serial EEPROM stores the setpoints for the backlighting and contrast and also for the appropriate
diagnostic data.
3.5.15 LCD Controller
The DC circuit contains an LCD controller that interfaces with the display.
3-13
3.5.16 Debouncing / Keypad Matrix
The matrix keys are debounced and then the microprocessor scans the matrix to determine what key was
depressed.
3.5.17 Rotary Encoder Control
The rotary encoder control circuit detects relative position, direction, and speed of the rotary encoder, all
within one detent of movement.
3.5.18 Audible Alarm Activation
The audible alarm is activated by either an input from the ELC, the power fail circuitry, or the test alarm
signal from the MCU. It will also occur when the wrong key has been depressed, an adjustable parameter
has reached its limit, or the error signal has been activated.
3.5.19 Audible Alarm Current Check
An internal test is performed to verify the audible alarm current is acceptable.
3.5.20 “Power-on“ in Safe State
The DC contains circuitry that causes the hardware to “power-on” in a safe state; which is when the
backlight is off, the display is off, and the Intermodule Communications Bus (ICB) is terminated. When
the MCU determines that no Vent Inop error exists, it lets the unit resume operation under normal
operating conditions.
3.5.21 Watchdog and Low Voltage Reset
The watchdog function has to be periodically reset by the microprocessor if a time-out period has been
exceeded. This function is designed to reset the processor if the software gets lost. When a low logic level
is detected, the ELC will be activated resulting in a system shutdown.
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3-14
Chapter 3: Description and Theory of Operation
3.6 Airflow Module (AFM)
The AFM is a submodule of the Pressure Control (PC). The AFM receives power from the PC and provides the following analog signals to the PAS:
a. Gas flow indication
b. Pressure indication
c. Temperature indication
To provide indications accurate enough for system requirements, the AFM must be calibrated. Calibration data is stored in a nonvolatile memory that is part of the AFM. The flow, pressure, and temperature
indications are for the ventilator gas stream flowing through a “flow body” attached to the AFM circuit
board.
3.6.1 Flow Body
The flow body, with laminar flow element, is added to the ventilator gas stream, creating a small pressure
differential to short a fraction of the flow through the AFM sensor. Inlet, outlet, and pressure ports are
part of the flow body for tubing attachment to the AFM electronic sensors. Also, a hole is molded into the
flow body to position the temperature sensor. The body has molded feet for attaching it to the AFM
circuit board assembly.
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And/Or Oxygen Supply
Figure 3-6
AFM Block Diagram
BiPAP Vision Service Manual
Chapter 3: Description and Theory of Operation
Airflow Module (AFM) (Continued)
3.6.2 Analog Reference
The PC provides the AFM with power in the form of +12 VDC, –12 VDC, analog ground, +5 VDC, and
digital ground. An analog voltage reference supply is derived from the +12 VDC to power the pressure
and flow sensors so their bridge outputs can be factory calibrated.
3.6.3 Flow Indication
Total gas flow indication is provided by MT1. It is then amplified by an instrumentation amplifier, lowpass filtered, and sent to the PC board for conversion.
3.6.4 Pressure Indication
MT2, a precision compensated pressure sensor, provides unit outlet pressure indication. The sensor is
followed by a low-pass filter and a differential amplifier, and then sent to the PC board for conversion.
3.6.5 Temperature Measurement
The temperature is measured using a sensor inserted into a molded hole in the flow body. The BiPAP
Vision requires temperature indication to correct air density and detect an undesirable temperature rise in
the patient circuit.
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3.6.6 Calibration
A data acquisition system, operating on a personal computer, is the control platform for AFM calibration
of temperature, pressure, and flow. Correction factors are derived and stored in the AFM module in an
EEPROM, with calibration accomplished by balancing the flow transducer bridge with an EEPOT. The
PAS uses temperature, pressure, and flow to correct for actual operating conditions. Once calibrated, the
AFM is interchangeable with other AFM assemblies.
NOTE: Calibration is factory programmed only.
3.6.7 Module Detection
The PC must know the AFM is connected, since it is required for normal operation of the ventilator. An
extra line pulls a PC microcontroller line near zero volts. If the line is above two volts, the AFM is not
connected, and the PC will transition to the error state.
BiPAP Vision Service Manual
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Chapter 3: Description and Theory of Operation
3.7 Oxygen Module (OM)
The OM is an optional submodule of the Pressure Control (PC). It receives power from the PC and
provides an analog signal to the PC for oxygen flow indication. To provide indications accurate enough
for system requirements, the OM must be calibrated. Calibration data is stored in a nonvolatile memory
that is part of the OM. The flow indication is for the ventilator pure oxygen stream flowing through a flow
body attached to the OM circuit board.
Figure 3-7
OM Block Diagram
PC
1045049
BiPAP Vision Service Manual
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