QL lamp gets more flexible
QL lamp gets more flexible
Philips announced a set of new features for its QL lamp at the Hannover fair: a smaller ballast, a discharge vessel that is easier to install and replace, and a design with an inherently lower production of EMI, thereby eliminating the need for shielding.
The lamp's high-frequency ballast (230-V versions) is now 25% narrower and 10% shallower with the same overall length. The improved lamp system also offers reduced electromagnetic interference (EMI) as an inherent design feature; i.e., the former need to use the luminaire as a shield for EMI has been eliminated. This should allow designers more freedom in designing luminaires, but more importantly, luminaire manufacturers can now design a luminaire without having to test it for radiomagnetic interference. Thus a manufacturer who wants to make just a few units of a luminaire would no longer have to carry out costly testing.
The reduction in EMI was achieved by improving the system electronics and the inductive power coupler which transfers energy from the HF ballast to the discharge vessel.
Another improvement concerns the discharge vessel itself, which now can be installed and changed without the need for special tools. At first glance, this would seem to be a feature of marginal importance with a lamp system rated to last 60 000 hours. However, in its promotional material, Philips points out the advantage for designers and architects of being able to pick the preferred lamp colors at the last minute, even after the system has been installed. (The QL system is basically a fluorescent system, with a spectral distribution and a color temperature range similar to those of fluorescent lamps.)
Since the QL lamp was first introduced in 1991 ("60 000 hours of no maintenance ", IAEEL Newsletter 1/92), it has not been selling as well as Philips had hoped. Therefore, in 1995, Philips extended the warranty period from one to five years. The newly announced improvements don't change the lamp's relatively low system efficacy (~65-70 lumen/W, similar to that of an integral CFL and considerably lower than that of full-size fluorescent lamps or metal-halide lamps).
On the other hand, the lamp is still unique with its 60000 hours rated life (failure rate less than 20%). Where system life is paramount, the above improvements address the concerns of luminaire manufacturers and specifiers, and should make the lamp more attractive. Philips has also announced a high-lumen-output lamp: a package with 10-11 000 lumen compared with today's 3 500 and 6 000 lumen packages, which should further increase the number of possible applications. (See also: Letters and comments.)
Nils Borg