Endurance LED bulb and relation to warmup measurement

Posted by Marcel van der Steen in Explanation No Comments»

hourglass-couplesAt OliNo we do a warm-up measurement on the lamps we test. During this warm-up until stabilization, a lot of the LED lamps show a decrease in consumed power and as well in light output. When the drop in light output is significantly bigger than the drop in consumed, this could be an indication of a not too long lifetime.

Color Quality Scale (CQS): Measuring the color quality of light sources

Posted by Marcel van der Steen in Explanation 11 Comments»

CIELabThe Color Rendering Index (CRI) is a quantitative measure of the ability of a light source to reveal the colors of various objects faithfully in comparison with an ideal or natural light source. The CRI is originally designed to evaluate fluorescent lamps. The CRI was intended to measure the ‘naturalness’ of objects’ colors, not preference. It has been found that the CRI is not reliable when used for LED lamps.

A successor, the Color Quality Scale (CQS), has implemented a number of improvements making it an alternative to the CRI and a better method for determining the color quality.

Difference Qlumedit and LDTeditor

Posted by Marcel van der Steen in Explanation No Comments»

QlumeditVsLDTeditorWith every lamp measurement comes an eulumdat file. This is a photometric file enabling you to simulate light distribution and light patterns in a certain area like an office, or on streets etc.

It appears that two programs, Qlumedit, and LDTeditor, do read in differently an equal eulumdat file when symmetry is present along the C90 C270 axis.

Personally, I do not understand the way LDT editor does it.

Update 3 March 2015: One more catch with DIalux and IES file. Dialux does not well understand dimensions used in IES files.

Advantages with a high S/P ratio

Posted by Marcel van der Steen in Explanation, Lamps No Comments»

lli_bv-high-bay-industrial-led-fixt-48-pcs-cree_s_and_p_spectra_at_1m_distanceThe S/P ratio has been explained before on this website. Now two Technical Memorandums (TM 12-12 and TM 24-13) of the Illuminating Engineering Society of North America (IESNA) elaborate on how and how much advantage one can make on using light with a high S/P ratio.

In short it comes down to this: at low environmental light levels (such as in streets at night with street lights on) your eye works with night vision (you loose the colors in your view but still can see a lot of details and overview with only moon light and light from stars). Lamps with a specific light (a specific spectrum) suited for this night vision (meaning high S/P ratio) will lead to an increase of brightness perception. So we need less light for the same brightness impression.

A second effect is valid for light levels indoor (reading, work on computer, work on electronic and mechanic setups, repairing things etc). When you use light with a high blue content (cold white, meaning also high S/P ratio) then this results in a decrease of pupil size which results in a sharper view. Thanks to this the average light level can go down to still have the same view-efficiency.

Inrush current for (led) light bulbs

Posted by Marcel van der Steen in Explanation, Lamps 27 Comments»

In this article I explain the inrush current phenomenon for cold lamps. This is the current that flows in a short time period just after switch on of the (grid)voltage. This current peak for an (led) light bulb is directly comparable to that of a motor. The inrush current measurement function of for instance a digital multi meter is for the lamp inrusch current not suitable.

The measurements on the inrush current at the measured lamps is done in a way that gives relevant info of the peak currents and a parameter is derived that is needed in selecting the correct fuses.

Dimming of linear halogen lamp with phase cut dimmers

Posted by Marcel van der Steen in Explanation, Lamps No Comments»

This is an article that shows the dimming results of a linear halogen light bulb that is dimmed by forward phase-cut (LR) and backward phase-cut dimmers (tronic, RC). The halogen lamp is well dimmable in the sense of dimming the amount of light. The images created show what that means in terms of light output as a function of dim-position.

What is remarkable is the amount of power still being high when the light has been dimmed a lot.

The graphs can be used to compare other types of lamps that are dimmed, in order to be able to judge whether the dimming works well or not.

EU Energy label for lamps Update Sept 2013

Posted by Marcel van der Steen in Explanation No Comments»

One of my customers informed me about an update of the EU Delegated Regulation (A regulation shall have general application. It shall be binding in its entirety and directly applicable in all Member States) about the energy labelling of lamps. I read through the regulation and present here a summary.

The regulation states that these new labels need to be introduced a of Sept 2013 (for new products). OliNo will deliver the new labels (6 variants in total) derived from our measurements and completed with the supplier’s name or trade mark and the supplier’s model identifier.

Blue light hazard for the human eye

Posted by Marcel van der Steen in Explanation 2 Comments»

blauw-licht With the ledlamps becoming more and more powerful and given that the blue content of the light from leds in increasing as well, there is a growing concern for blue light hazard.

The IEC 62471:2006 norm explains about how to measure Blue Light Hazard, tha could lead to photoretenitis. This norm has an update in 2008. That update refers to the European Directive 2006/25/EC that contains the ELs. This article explains the way OliNo deals with this norm to measure the blue light hazard (only as an indication!) of the lamps it measures.

Update 28 April 2012: the dimensions of the brightest part of the illuminated part are taken for the calculation (of interest only in non-homogeneous sources).

Non-visual effects of ocular light on human beings – The biological factors

Posted by Marcel van der Steen in Explanation 2 Comments»

This article explains a bit about the biological effects of light on human beings. It appears that next to rod and cones there are other cells sensitive to a certain part of the light spectrum and that influences our daily rhythm (circadian cycle); this is the cycle of sleep and being awake, where a hormone like melatonin plays an important role.

The spectrum of the light enables to compute the biological effect that it can provoke, amongst others in (1) the suppression of melatonin in the night and in (2) shifting the circadian phase. I used the vornorm DIN V 5031-100:2009-06 as the basis of the computation of several interesing parameters coming from the light spectrum.