IEC TS 62504 pdf download.General lighting – LEDs and LED modules – Terms and definitions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in IEC 60050-845 and the following apply. 3.1 ambient temperature t amb average temperature of air or another medium in the vicinity of the LED or LED module NOTE 1 During the measurement of the ambient temperature, the measuring instrument/probe should be shielded from draughts and radiant heating. [IEC 60050-826:2004, definition 826-1 0-03, modified] [see also CIE 1 27, Subclause 2.2.5] NOTE 2 Ambient temperature is expressed in Celsius degrees. 3.2 angular subtense α angle subtended by an apparent source as viewed from a point in space The angle extension is determined by the observation distance, but at no distance smaller than the minimum distance of accommodation. NOTE 1 The location and angular subtense of the apparent source depends on the viewing position in the beam. NOTE 2 The angular subtense of an apparent source is only applicable in the wavelength range from 380 nm to 1 400 nm, where eye hazard exists.NOTE 3 The angular subtense of the source should not be confused with the beam divergence. The angular subtense of the source cannot be larger than the divergence of the beam, but it is usually smaller than the divergence of the beam NOTE 4 In terms of optical radiation safety, the LED radiation source is a “middle sized source”, whose images are projected on the retina under angles between 1 ,5 mrad and 1 00 mrad, i.e. the diameter of the retina image extends between about 25 µm and 1 700 µm. For such sources, particularly, the hazard is strongly related to the angular subtense on the observer’s retina. [IEC 60825-1 :2007, 3.7, modified] NOTE 5 The angular subtense is expressed in degrees (°). 3.3 apparent source for a given evaluation location of the retinal hazard, the real or virtual object that forms the smallest possible retinal image (considering the accommodation range of the human eye) NOTE 1 The accommodation range of the eye is assumed to be variable from 1 00 mm to infinity. The location of the apparent source for a given viewing position in the beam is that location to which the eye accommodates to produce the most hazardous retinal irradiance condition. NOTE 2 This definition is used to determine, for a given evaluation position, the location of the apparent origin of laser radiation in the wavelength range of 380 nm to 1 400 nm. In the limit of vanishing divergence, i.e. in the case of a well collimated beam, the location of the apparent source goes to infinity. [IEC 60825-1 :2007, 3.1 0, modified] 3.4 beam angle angle between two imaginary lines in a plane through the optical beam axis, such that these lines pass through the centre of the front face of the lamp and through points at which the luminous intensity is 50 % of the centre beam intensity [IEC/TR 61 341 :201 0, 2.4] NOTE The beam angle is expressed in degrees (°).3.5 bin restricted range of LED performance characteristics used to delimit a subset of LEDs near a nominal LED performance as identified by photometric performance and forward voltage NOTE As the result of small but meaningful variations in the manufacturing process of LED wafers and subsequent dies, the electrical and photometric characteristics of LEDs may vary from LED to LED, even when the dies are from the same wafer. LEDs are sorted or binned in accordance with these characteristics, but there is no existing standard for binning. 3.6 built-in LED module LED module, generally designed to form a replaceable part built into a luminaire, a box, an enclosure or the like and not intended to be mounted outside a luminaire, etc. without special precautions 3.7 built-in self-ballasted LED module self-ballasted LED module, generally designed to form a replaceable part built into a luminaire, a box, an enclosure or the like and not intended to be mounted outside a luminaire, etc. without special precautions 3.8 chromaticity coordinates ratio of each of a set of three tristimulus values to their sum
IEC TS 62504 pdf download
