Replacement Processes for Light Emitting Diode (LED) Traffic Signals

2009 ◽  
Author(s):  
◽  
◽  
Keyword(s):  
Light Emitting Diode ◽  
Traffic Signals ◽  
Light Emitting

Response to Simulated Traffic Signals Using Light-Emitting Diode and Incandescent Sources

2000 ◽  
Vol 1724 (1) ◽  
pp. 39-46 ◽  
Author(s):  
John D. Bullough ◽  
Peter R. Boyce ◽  
Andrew Bierman ◽  
Kathryn M. Conway ◽  
Kun Huang ◽  
...  
Keyword(s):  
Reaction Time ◽  
Light Emitting Diode ◽  
Reaction Times ◽  
Reaction Time Data ◽  
Traffic Signals ◽  
Time Data ◽  
Light Emitting ◽  
Color Identification ◽  
Mean Reaction Time

Simulated light-emitting diode (LED) traffic signals of different luminances were evaluated relative to incandescent signals of the same nominal color and at the luminances required by the specifications of the Institute of Transportation Engineers. Measurements were made of the reaction times to onset and the number of missed signals for red, yellow, and green incandescent and LED signals. Measurements also were made of subjects’ ability to correctly identify signal colors and of their subjective brightness and conspicuity ratings. All measurements were made under simulated daytime conditions. There were no significant differences in mean reaction time, percentage of missed signals, color identification, or subjective brightness and conspicuity ratings between simulated incandescent and LED signals of the same nominal color and luminance. Higher luminances were needed for the yellow and green signal colors to ensure that they produced the same reaction time, the same percentage of missed signals, and the same rated brightness and conspicuity as a red signal at a given luminance. Equations fitted to the reaction time data, the missed signals data, and the brightness and conspicuity ratings for the LED signals can be used to make quantitative predictions of the consequences of proposed changes in signal luminance for reaction time, brightness, and conspicuity.

scholarly journals Glare by Light Emitting Diode (LED) vehicle traffic signals

2015 ◽  
Vol 10 (1) ◽  
Author(s):  
Pablo Ixtaina ◽  
Matias Presso ◽  
Nicolás Rosales ◽  
Gustavo H Marin
Keyword(s):  
Light Emitting Diode ◽  
Traffic Signals ◽  
Light Emitting ◽  
Vehicle Traffic

Detection and Identification of Light-Emitting Diode Traffic Signals by Protan Observers

2003 ◽  
Vol 1844 (1) ◽  
pp. 52-58 ◽  
Author(s):  
Michelle Kun Huang ◽  
John D. Bullough ◽  
Peter R. Boyce ◽  
Andrew Bierman
Keyword(s):  
Light Emitting Diode ◽  
Visible Spectrum ◽  
Normal Subjects ◽  
Traffic Signals ◽  
Detection Performance ◽  
Identification Accuracy ◽  
Dominant Wavelength ◽  
Light Emitting ◽  
Red Led ◽  
Color Identification

Protan observers have lower spectral sensitivity than color-normal observers at long wavelengths of the visible spectrum. Responses of protan and color-normal subjects to light emitting diode (LED) and incandescent traffic signals of red and yellow nominal color during simulated daytime viewing conditions are described. Reaction times, missed signal percentages, and color-identification accuracy were measured. The results indicate that for protans, detection performance to red LED signals was enhanced when the dominant wavelength was moved toward shorter wavelengths, but this shift also appeared to decrease their ability to correctly identify the signal color. Although the yellow LED signal used in this study provided similar detection performance for protans as a yellow incandescent signal, its dominant wavelength was sufficiently long for it to sometimes be confused with red. In general, the results of this study are consistent with the 1994 recommendations of the Commission Internationale de l’Éclairage for signal colors to be seen by color-normal and protan observers. Nonetheless, neither detection nor color identification for protans approached that of color-normal observers.

Daytime Photometric Requirements for Pedestrian Signals

1997 ◽  
Vol 1605 (1) ◽  
pp. 41-48
Author(s):  
Douglas Mace ◽  
Mark Finkle ◽  
Sara Pennak
Keyword(s):  
Light Emitting Diode ◽  
Traffic Signals ◽  
Worst Case ◽  
Light Emitting ◽  
Message Testing ◽  
Pedestrian Traffic ◽  
Rectangular Signal ◽  
Display Configuration ◽  
Full Power ◽  
Pedestrian Signals

Forty-eight senior citizens participated in a field study of the visibility of letters and symbols in pedestrian traffic signals. Subjects were asked to identify signal messages from distances of 18.3 m and 29.3 m, with signal voltage set at 100 percent, 75 percent, and 50 percent of full power. Incandescent, fiber-optic, and light-emitting diode commercially available pedestrian signals were tested, including 22.9-cm and 30.5-cm rectangular signal housings and two round red-amber-green signals with symbol masks. Each subject was asked to identify the signal’s location in the test stimuli array, to name the signal’s display configuration (Walk, Don’t Walk, walking person, or hand), and to assess the signal’s brightness on a five-point scale. Analyses also were conducted on the percentage of responses about “too bright” signals and subject uncertainty about the signal message. Testing was conducted only on bright sunny days but did not include the worst-case condition of direct sunlight on the signal face. The analysis of recognition, uncertainty, and “too bright” responses suggested that a signal intensity of 25 cd minimizes the frequency of both “too bright” and uncertain responses regardless of size, distance, or technology, or whether the message is symbol or text. The data further suggest that 22.9-cm incandescent signals provide sufficient visibility with less phantom effect than 30.5-cm signals.

Synchronization of Chaotic Quantum Dot Light Emitting Diodes under Optical Feedback Effect

2020 ◽  
pp. 144-148
Keyword(s):  
Quantum Dot ◽  
Delay Time ◽  
Chaos Synchronization ◽  
Optical Feedback ◽  
Light Emitting Diode ◽  
Feedback Effect ◽  
Complete Synchronization ◽  
Light Emitting ◽  
Coupling Methods ◽  
Coupling Parameters

Chaos synchronization of delayed quantum dot light emitting diode has been studied theortetically which are coupled via the unidirectional and bidirectional. at synchronization of chaotic, The dynamics is identical with delayed optical feedback for those coupling methods. Depending on the coupling parameters and delay time the system exhibits complete synchronization, . Under proper conditions, the receiver quantum dot light emitting diode can be satisfactorily synchronized with the transmitter quantum dot light emitting diode due to the optical feedback effect.

Effects of Nitridation Time on Top-emission Inverted Organic Light Emitting Diode

PIERS Online ◽  
2007 ◽  
Vol 3 (6) ◽  
pp. 821-824 ◽  
Author(s):  
Chien-Chang Tseng ◽  
Liang-Wen Ji ◽  
Yu Sheng Tsai ◽  
Fuh-Shyang Juang
Keyword(s):  
Light Emitting Diode ◽  
Light Emitting ◽  
Organic Light Emitting Diode ◽  
Nitridation Time ◽  
Organic Light
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