OSRAM DULUX F - Manual (Page 22)

Economical long-life light sources with plug-in bases
Compact Fluorescent Lamps OSRAM DULUX ®
Technical Guide
20
1.4 Technical design and operation
The low pressure discharge method of generating light is one of the most economic. It needs only
one quarter (or a fifth using an ECG) of the electrical energy which an incandescent lamp with the
same light output would need.
In OSRAM DULUX ® lamps, as in conventional fluorescent lamps, light is generated by a low-pres-
sure gas discharge. Electrical current is conducted through the tube from one electrode to the
other. The electrons excite mercury atoms so that they emit optical radiation. This radiation is con-
verted into visible light by the tri-phosphor coating on the inner wall of the tube.
The principle of light generation in a fluorescent lamp
High luminous efficacy (the relationship between luminous flux and power consumption) is achieved
when an optimum mercury vapour pressure exists in the discharge tube. This depends on the tem-
peratures on the inner tube wall and is regulated by the vaporisation of mercury and its condensa-
tion at the cool zones (cold spot) of the discharge tube.
In contrast to fluorescent lamps, the corners at the top of the discharge tube on an OSRAM
DULUX
® lamp act as cold spots. The temperature at these cold spots depends to some extent on
the burning position of the lamp and the ambient temperature.
Good conditions for luminous flux and lamp performance exist when the temperature at these cold
spots is between 40ºC and 50ºC.
Technical design of OSRAM DULUX® S and OSRAM DULUX® T PLUS