Spacelabs Healthcare elance 5, Руководство по обслуживанию

Страница: 21 / 94

Theory
SpO
2
Block Diagram
- Patient SpO
2
detection is by comparison of Red and IR light absorption by patient arterial blood.
- The current for driving the LED is controlled by the ATMEGA162V microcontroller.
-
The signal detected at the SpO
2
sensor is amplified and captured at by the sample and hold
circuitry. Then, the signal is further amplified and sent through a 7-8Hz LFP.
-
Each of dynamic RED and IR and static RED and IR signals are compare with the ambient signal
at the Differential Amplified. This is to derive the SpO
2
IR, SpO
2
IR DC, SpO
2
RED, SpO
2
RED
DC signals.
- The SpO
2
DC, SpO
2
IR, SpO
2
IR DC, SpO
2
RED, SpO
2
RED DC signals are sent to ATMEGA
microcontroller for processing.
3-5
Diff.
AMP
A
D
C
S/H
SpO
2
Input
S/H
S/H
LPF
LPF
Diff.
AMP
Diff.
AMP
Diff.
AMP
IR
DC
IR
Red
DC
Red
AMP AMP
LPF AMP
AMP
Red
IR
Ambient