GE Giraffe Blue Spot PT Lite, Руководство по эксплуатации, техническому обслуживанию и ремонту

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Chapter 6: System Description
The Giraffe Blue Spot PT Lite is a medical device designed to treat neonatal jaundice by providing blue
therapeutic light to patients. White light is comprised of light wavelengths from throughout the spectrum.
However, the wavelengths of light that actually provide therapy reside only between 410 and 460
nanometers. This light appears blue to the eye and is the specific output of the Giraffe Blue Spot PT Lite.
The system is composed of a light box generating light and a light pipe through which the light from the
LED is transmitted and projected upon patients.
1. Light box: The light box functions as the light generator, user control panel, and the device mounting
structure through use of a dovetail clamp. The light box contains the following major components:
Component Description
Therapeutic-
light LED
assembly
The therapeutic-light LED is mounted directly to a fan-cooled heat sink and also has
a built-in thermistor output which is used to produce the temperature fault alarms.
The thermistor signal is first conditioned by the LED driver board and then routed
to the control board. The LED assembly contains a reflector which serves to narrow
and direct the output LED light into the light pipe. A 12 VDC brushless fan is mounted
to the heat sink. The fan pulls air from the lower chamber through a dividing baffle.
The baffle ensures that the heat sink exhaust heat is directed to the exhaust vents
to prevent recirculation. The fan is installed in a certain position to pull air from the
lower chamber (cool zone) to the upper chamber (hot zone). Backward installation of
the fan causes reverse air flow from hot zone to cool zone and negatively impacts
the heat sink cooling. During over-temperature/under-temperature conditions,
the fan keeps running to bring the LED assembly temperature to the ambient
temperature.
LED driver
board
This board generates a 5 VDC supply for powering therapeutic-light LED and control
board and routes the 12 VDC supply to the cooling fan. The driver board is set in the
factory such that sufficient driver current for the therapeutic-light LED is provided.
The voltage and current to the therapeutic-light LED are factory-sealed and non-
adjustable in the field. Therefore, the LED driver board and the therapeutic-light LED
assembly shall always be replaced in pair with a new factory-set pair (Mixing and
matching is not allowed.).
Control board
The control board is mounted to the inside of the unit cover and provides the system
controls, indicator LEDs, hour meter display, standby/on switch, and user interface.
The control board 5 VDC supply is provided by the LED driver board. The control board
sends the commands to the LED driver board to operate the therapeutic-light LED and
the fan.
The control board includes the hour meter display which shows the total time the
therapeutic-light LED is illuminated. The hour meter is not resettable. Therefore,
new product units ship with readings other than zero from the factory because of
production tests. The hour meter illuminates whenever the AC power is provided to
the system.
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