This paper presents the research of optimization of road lighting energy consumption by utilizing the fact of human twilight and night vision (mesopic vision) dependency on luminance level and lamp’s light spectral composition. The research was conducted for a suburban street illuminated by smart LED road luminaires with a luminous flux control system with which different luminance levels can be achieved on the road. This road is an access road leading to a town located on the outskirts of Warsaw which is the capital of Poland and a large metropolitan area. Therefore, the traffic here is quite heavy on this road in the morning and in the evening and it is very light at other times of the day. In accordance with EN 13201 standard, lighting control can be applied to illuminate this road. This paper compares energy consumption for different lighting scenarios of the road in question. In the first scenario, the road luminance is compliant with M4, M5, and M6 lighting class requirements depending on the time of the day. In the second scenario, for each M lighting class, the values of luminance levels provided by EN 13201 standard have been reduced to the values resulting from their conversion to the corresponding mesopic luminance values. The conducted research has shown that a 15% saving per year in electricity consumption on the road is possible with such a conversion. Therefore, energy efficiency of a lighting installation can be improved by matching the lighting levels provided by the standard to the mesopic vision.

Luminance measurements are the least frequent of all photometric measurements. This article characterizes and systematizes the various methods of luminance measurement. In particular, the method of direct luminance measurement using modern luminance meters (ILMD) is described in detail. This paper presents the results of the study on the influence of the measurement distance on the luminance measurement results. Two ILMD meters (laboratory and portable) and a luminance standard were used in this study. The conducted research showed that an incorrectly chosen measuring distance can lead to significant measurement errors of up to several tens of percent. In addition, the possible impact of incorrect measurements on the design of an interior lighting installation was presented. It was shown that the selected interior lighting installation can consume more than 40 percent more electricity compared to the installation based on the correct luminance measurements of the luminaires with diffuse shades. In the final stage of the study, the definition of the photometric test distance for luminance measurements using ILMD was proposed. The test results can be particularly useful for the luminance measurements of OLEDs or the luminaires with diffuse luminous character. However, these results can also be used for luminance measurements of other light sources and luminaires.

Chip-On-Board Light-Emitting Diodes (COB LED) are increasingly more common. Their development in recent years has directly contributed to increasing the power of LED sources, whilst simultaneously increasing the luminous flux from the entire COB. Consequently, it has led to new developments in some applications. Information regarding the size of the light source luminous surface and luminance distribution on its surface is critical for a designer whilst designing optical systems. The purpose of this conducted research was to establish to what extent luminance distribution is even on the examined COB LEDs. In order to verify luminance distributions on an LED surface, direct measurements with a matrix luminance measuring device were made. As a result of the research, it has been observed that luminance distribution is not even, and in many cases luminance maximum does not fall in the geometric center of the luminous surface, which was initially expected. So, it has been concluded that while designing optical systems for COB LEDs, irregular luminance distribution on their surface needs to be considered.

This article presents the research on a road lighting design. In this kind of design for a specific type of a roadway, the number and spacing of luminaires are calculated on the basis of luminaire photometric parameters such as intensity curve (LPIC) and luminous flux. The values of these parameters are measured using the luxmeter, i.e., a measuring instrument in which the spectral sensitivity should imitate spectral sensitivity of the human eye V(λ). However, the luxmeter’s spectral sensitivity S(λ) is not perfectly matched with the required one and varies for different instruments, resulting in measurement errors. To avoid this measurement error, the spectral mismatch correction factor (SMCF) should be applied to luxmeter’s readings. For a given luxmeter, the SMCF values depend on the measured light’s spectral composition SPD (described also by the lamp’s correlated color temperature CCT). Unfortunately, many laboratories do not apply SMCF to their luxmeter readings. Typical measurement laboratories are not in possession of SMCF data as this kind of data is hard to obtain and can be provided only by the state-of-the-art photometric laboratories for a high cost. Consequently, these typical measurement laboratories provide inaccurate LPIC data to costumers. In this article, it has been shown that a design process of road lighting installations needs to be based on lighting fixture LPIC’s measurements with SMCF values being taken into account. Omitting this fact may result in road lighting installation made on the basis of a design utilizing incorrect LPIC data, which would have higher energy consumption then expected at a design stage.

Over the last few years, light-emitting diodes have completely dominated the lighting field. In road lighting, high-power LEDs have replaced traditional light sources. That is why various technical aspects of LEDs have been researched extensively worldwide. However, little research has been conducted in the area of luminance measurement. This paper reviews the methods for measuring the luminance of high-power LEDs. Particular attention is paid to the influence of the measurement distance on the measurement results. Next, the results of the tests using a modern image luminance measuring device (ILMD) for luminance measurements are presented. It is concluded that it is necessary to redefine the photometric test distance. The conducted research demonstrates that an incorrectly selected test distance can lead to the huge errors of several hundred per cent or more. In addition, the possible impact of the incorrect measurements on the design of road lighting installations is presented. It is shown that a road lighting installation can use over 300% more electrical energy compared to the installation based on the correct luminance measurements of single LEDs. In the final stage of the research, the definition of the photometric test distance for LED measurements using ILMD is proposed. The results of the research can also be useful for the luminance measurements of other types of LEDs.

This work presents luminance distributions across the surface of mid- and high-power diodes. The changes in luminance on diode surfaces following changes in the observation angle were verified. On the basis of the conducted tests, non-uniform luminance distribution on LED surface for diverse observation angles (including the axial direction) was observed. Moreover, it was concluded that luminance changes is not in line with the Lambert’s law. As the result of the research it was also concluded that alterations of the power-supply conditions do not exert any significant impact on the gradient of luminance changes on the surfaces of examined LEDs. Full Text: PDF ReferencesJ. Fan, J. Cao, Ch. Yu, Ch. Qian, X. Fan, G. Zhang, A design and qualification of LED flip Chip-on-Board module with tunable color temperatures, Microelectronics reliability, ISSN 0026-2714, Nº. 84, 2018, pp. 140-148, CrossRef K. Bonislawski, I. Fryc, The study on optical properties of LEDs used for vehicle control lighting, Przeglad Elektrotechniczny, 2012, ISSN 0033-2097, Vol. 88, Issue 3A, pp. 119-120 DirectLink T. Kawabata, Y. Ohno, Optical measurements of OLED panels for lighting applications, Journal of Modern Optics 60(14), 2013, pp. 1176-1186 CrossRef P. Pracki, U. Blaszczak, The issues of interior lighting on the example of an educational building adjustment to nZEB standard, IEEE Lighting Conference of the Visegrad Countries (Lumen V4), IEEE (17 November 2016) CrossRef P. Tabaka, Analysis of electrical parameters of prime set bulb equivalents suitable for dimming, Przeglad Elektrotechniczny, 2015, R. 91, No. 5, pp. 100-106, ISSN 0033-2097 CrossRef D. Czyżewski, The street lighting luminaires with LEDs. Przeglad Elektrotechniczny, 86, 2009, pp. 276-279 DirectLink C. C. Miller; Y. Zong; Y. Ohno, LED photometric calibrations at the National Institute of Standards and Technology and future measurement needs of LEDs, Proc. SPIE Vol. 5530, Fourth International Conference on Solid State Lighting; (2004) CrossRef D. Mozyrska Dorota; M. Wyrwas; I. Fryc, The determination of the LEDs colorimetric parameters, in the range of their operating temperature, Przeglad Elektrotechniczny, Vol. 88, Issue: 4A, 2012, pp. 232-234 CrossRef K. Baran, A. Różowicz, H. Wachta, S. Różowicz, D. Mazur, Thermal Analysis of the Factors Influencing Junction Temperature of LED Panel Sources, Energies, 12, 3941, 2019 CrossRef D. Czyżewski, Research on Luminance Distributions of Chip-On-Board Light-Emitting Diodes, Crystals 9(12), 645, 2019. CrossRef L. Zheng, Z. Guo, W. Yan, Y. Lin, Y. Lu, H.C. Kuo, Z. Chen, L. Zhu, T. Wu, Y. Gao, Research on a Camera-Based Microscopic Imaging System to Inspect the Surface Luminance of the Micro-LED Array. IEEE Access 6, 2018, 51329-51336. CrossRef S. Słomiński, Selected Problems in Modern Methods of Luminance Measurement of Multisource LED Luminaires. Light Eng. 24, 2016, pp. 45-50. DirectLink I. Fryc, P. Jakubowski, K. Kołacz, Analysis of optical radiation parameters of compact discharge HID lamps and LED COB modules used for illuminating shop windows, Przeglad Elektrotechniczny, 2017, R. 93, nr 11, pp. 186-189. CrossRef I. Fryc, Measurement techniques of optical LEDs properties performed with compliance conformity with CIE 127:2007 standard, Przeglad Elektrotechniczny, 2009,ISSN 0033-2097,Vol. 85,Issue:11,pp.317-319. DirectLink I. Fryc, T. Dimitrova-Grekow, An Automated System for Evaluation of the Quality of Light Sources, 2016 IEEE Lighting Conference of the Visegrad Countries (Lumen V4), IEEE (17 November 2016), CrossRef CIE 235:2019, Optical measurement of led modules and light engines, ISBN 978-3-902842-25-1, DOI: 10.25039/TR.235.2019. CrossRef D. Czyżewski, Investigation of COB LED luminance distribution, In Proceedings of the 2016 IEEE Lighting Conference of the Visegrad Countries (Lumen V4), IEEE (17 November 2016) CrossRef I. Rotscholl, K. Trampert; U. Krüger; F. Schmidt, Spectral near field data of LED systems for optical simulations, Proceedings SPIE Volume 11144,Phot. and Educ. in Measur. Sc. 2019, CrossRef