luminance

Articles, guides, and products tagged "luminance" — a combined view of every catalogue resource on this topic.

User guide

Display and HMI engineering for electric scooters: sunlight-readability photometry (CR, cd/m², transflective LCD), glanceability ergonomics (ISO 15008, NHTSA 2-glance ≤ 2 s / 12 s, Fitts' law, Frutiger/DIN 1450), adaptive brightness (Weber-Fechner, PWM flicker per IEEE 1789-2015), environmental robustness (IP66, ISO 16750-3 vibration, IEC 60068 thermal −20…+70 °C), EMC (CISPR 14-1, ECE R10) and functional safety (IEC 62368-1, ISO 13849-1)

An engineering deep-dive into the one bidirectional channel between e-scooter and rider — paired with the introductory survey «Display, throttle, and error codes» (parts/display-throttle-error-codes): matrix physics (TN LCD with 90° twisted nematic vs IPS LCD with in-plane molecular switching vs OLED with organic electroluminescence via electron-hole recombination vs E-paper with electrophoretic ink); sunlight readability as a photometric problem (contrast ratio CR=(L_max+L_amb·R)/(L_min+L_amb·R) with ambient reflection, why a 250 cd/m² LCD against 100 000 lx direct sun drops to CR=1.05:1 without an anti-reflective coating, and transflective LCD as a hybrid with ambient backlight); glanceability as safety-critical ergonomics (ISO 15008:2017 in-vehicle visual presentation with minimum character-height-to-distance ratio 1:200, ISO 9241-303:2011 visual ergonomics, NHTSA Driver Distraction Guidelines 2013 + SAE J2364 2-glance principle ≤2 s single + ≤12 s total, Fitts' law T=a+b·log₂(D/W+1) for button-reach time, sans-serif Frutiger 1976 + DIN 1450:2013 Schriften — Leserlichkeit, kerning, x-height ≥60 % cap-height); adaptive brightness (Weber-Fechner logarithmic perception ΔI/I=const, ambient light sensor 0.01-100 000 lx, PWM dimming for LCD backlight with flicker frequency ≥1 kHz per IEEE 1789-2015 No-Observable-Effect threshold); environmental robustness (IEC 60529:2013 IP66 ingress dust-tight+powerful jets, ISO 16750-3:2012 road vehicle mechanical loads 10-2000 Hz random vibration, IEC 60068-2-1/-2 temperature −20…+70 °C cycling, IEC 60068-2-27 mechanical shock 1500g 0.5 ms half-sine, IEC 60068-2-30 damp heat 25/40 °C 95 % RH, ASTM B117-19 salt spray 5 % NaCl 35 °C 96 h); EMC (CISPR 14-1:2020 household-appliance emission, UNECE Regulation 10 Rev 6:2017 vehicle EMC 30 MHz-1 GHz radiated, ferrite chokes for PWM-backlight harmonic suppression); functional safety (IEC 62368-1:2018 hazard-based safety engineering with ES1/ES2 energy-source classes + PS1/PS2 power source + MS1/MS2 mechanical source, ISO 13849-1:2015 PL_d performance level so that display failure does NOT cause throttle/brake loss); and the full comparison matrix of 12 standards (ISO 15008 + ISO 9241-303 + ISO 9241-11 + NHTSA/SAE J2364 + IEEE 1789-2015 + IEC 62368-1 + IEC 60529 + IEC 60068-2 + ISO 16750-3 + CISPR 14-1 + UNECE R10 + ISO 13849-1).

18 min read

User guide

E-scooter lighting and signaling engineering: photometry (lm / cd / lx / cd/m²), ECE R113 beam pattern, LED thermal physics, retroreflectivity RA cd/(lx·m²), and standards IEC 60809 / SAE J583+J586+J588 / ECE R148+R149 / EN 17128 §5.5–5.6 / StVZO §67 / FMVSS 108

An engineering deep-dive into the lighting and signaling subsystem of an e-scooter — parallel to the introductory overview at parts/lights-signaling: photometry as a distinct discipline from radiometry (luminous flux Φᵥ in lumens via CIE 1924 V(λ) photopic + 1951 V'(λ) scotopic luminous-efficiency functions; K_m = 683 lm/W peak sensitivity at 555 nm; lumens vs candela vs lux vs cd/m²; Lambertian source I = I_0 · cosθ vs isotropic; inverse-square law E = I / d² for a point source), the headlamp beam pattern (ECE R113 Annex 4 photometric zones — B50L oncoming-glare 0.4 lx max @ 25 m, 75R road-illumination 12 lx min, HV horizon-point 0.7 cd min, vertical test point 50V, cut-off line with 1 % gradient by G = log(E_above / E_below); why asymmetric beam distinguishes the «transmitting» side from the «oncoming» side), LED thermal physics (Rθjc 5–15 K/W chip-to-package + Rθcb 1–5 K/W board + Rθba 10–30 K/W ambient via the electrical-thermal equivalent-circuit model; chromaticity shift Duv at high Tj > 105 °C from phosphor degradation; lumen-maintenance L70/L80/L90 lifetime in hours per IES TM-21-19 extrapolation method with Arrhenius equation k = A · exp(−E_a / kT); chromaticity shift Δuv ≤ 0.007 by TM-21 limit; IES TM-28-22 luminaire-level testing), optical design (TIR total-internal-reflection lenses with polycarbonate n = 1.586 vs PMMA n = 1.491 vs glass n = 1.52; reflector parabolic axis-of-revolution with focal length f; projector lens focal point + shield for cut-off; optical efficiency η_o = Φ_out / Φ_chip = 70–90 % for glass vs 60–80 % for polycarbonate; UV photodegradation via E_UV = hc/λ → polycarbonate ester-bond cleavage over 5–7 years outdoor exposure; chromatic aberration short-wavelength shift), retroreflectivity physics (RA coefficient in cd/(lx·m²) per CIE 54.2-2001 Standard Reflectance Geometry; observation angle α = 0.2° / 0.33° / 1° test values; entrance angle β = ±5° / ±30°; glass-bead n = 1.9–2.1 spherical optics with double refraction + back-reflection vs micro-prismatic full-cube triangular face refraction with theoretical 100 % efficiency; EN 471:2003 + EN ISO 20471:2013 class 2/3 minimum RA 100/500 cd/(lx·m²) for high-visibility apparel; ASTM E810-22 portable retroreflectometer + ASTM E811 hand-held test methods; CIE Photometric Geometry), photometric specifications for signal lamps (SAE J586 stop lamp 80 cd min center / 300 cd max; SAE J588 turn-signal lamp 80–700 cd front / 50–350 cd rear; ECE R7 brake lamp 60 cd min center / 18 cd at ±45°; ECE R6 direction indicator front 175–700 cd / rear 50–500 cd; IEC 60809 flash rate 60–120/min ±5 % deviation per cycle; ramp-up time < 200 ms), audible signaling acoustics (Lp dB(A) with 20 µPa reference; A-weighting curve attenuates < 500 Hz and > 5 kHz, reflecting equal-loudness contours per Fletcher-Munson 1933 + Robinson-Dadson 1956 + ISO 226:2023 equal-loudness contours; EN 17128:2020 § 5.6 minimum 70 dB(A) @ 2 m peak frequency 1–4 kHz; piezo speaker resonant frequency f_r 2.5–4 kHz via RLC equivalent circuit), and a full comparative matrix of 14 standards (IEC 60809:2015 + Amendments / SAE J583 Front Fog Lamp / SAE J586 Stop Lamp / SAE J588 Turn Signal Lamp / ECE R113 Rev 3:2014 Headlamps emitting symmetrical passing beam / ECE R148:2023 consolidated signal lamp / ECE R149:2023 consolidated road illumination / ECE R6 Direction Indicators / ECE R7 Position+Stop+End-outline Lamps / EN 17128:2020 PLEV § 5.5 lights + § 5.6 audible warning / FMVSS 108 49 CFR § 571.108 Lamps, Reflective Devices, and Associated Equipment / StVZO § 67 Germany Bundes-Ministerium für Verkehr / eKFV § 5 German Elektrokleinstfahrzeuge / CIE 54.2-2001 Retroreflection — Definition and Specification of Materials / EN 13356:2001 Visibility accessories); engineering ↔ symptom diagnostic matrix; 8-point recap.

18 min read