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Search Publications by: Yoshi Ohno (Fed)

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Displaying 26 - 50 of 197

Optical Measurements of OLED Panels for Lighting Applications

July 22, 2013
Author(s)
Tokihisa Kawabata, Yoshi Ohno
Optical characteristics of OLED panels have been investigated for the purpose of developing a test method for OLED panels for lighting applications. The electrical characteristics, total luminous flux and chromaticity (x, y), and their dependence on supply

Chapter 13. Color Quality of White LEDs

May 24, 2013
Author(s)
Yoshihiro Ohno
This chapter overviews the fundamentals of chromaticity and color rendering as the two important aspects of color quality of light sources for general illumination, with special focus on the use for solid state light sources. The section for chromaticity

EFFECT OF HIGH LUMINANCE SOURCES TO PERIPHERAL ADAPTATION STATE IN MESOPIC RANGE

April 15, 2013
Author(s)
Tatsukiyo (. Uchida, Yoshihiro Ohno
CIE 191:2010 recommends a mesopic photometry system that defines the spectral luminous efficiency function for peripheral visual tasks. For implementation of the system, the visual adaptation field, which takes into account the surrounding luminance effect

Four-color laser white illuminant demonstrating high color-rendering quality

July 4, 2011
Author(s)
Alexander Neumann, Jonathan Wierer , Wendy L. Davis, Yoshi Ohno, Steve Brueck, Jeff Tsao
Solid-state lighting is currently based on light-emitting diodes (LEDs) and phosphors. Solid-state lighting based on lasers would offer significant advantages including high potential efficiencies at high current densities. Light emitted from lasers

MEASUREMENT OF WEIGHTED LED RADIANCE RELATED TO PHOTOBIOLOGICAL SAFETY

December 1, 2010
Author(s)
Tongsheng Mou, Yuqin Zong, Yoshi Ohno
Optical radiation safety of light-emitting diode (LED) products is being addressed in the International Electrotechnical Commission (IEC) standard document 62471-2006. Measurement of weighted radiance of LEDs, used to assess the maximal exposure related to

Rationale of Color Quality Scale

June 10, 2010
Author(s)
Yoshihiro Ohno, Wendy L. Davis
The color quality of solid state lighting (SSL) products is critical and is the subject of increasing attention. The CIE Color Rendering Index (CRI) [1] has been widely used for many years. However, the CRI is 35 years old and various problems of the CRI

The Color Quality Scale

March 15, 2010
Author(s)
Wendy L. Davis, Yoshihiro Ohno
The Color Rendering Index (CRI) has been shown to have deficiencies when applied to white light-emitting diode (LED) based sources. Further, evidence suggests that the restricted scope of the CRI unnecessarily penalizes some light sources with desirable

Report on the Key Comparison CCPR K2.a-2003

October 30, 2009
Author(s)
Yoshihiro Ohno, Steven W. Brown, Thomas C. Larason
Under the framework of Mutual Recognition Arrangement (MRA) for national measurements standards and for calibration and measurement certificates issued by National Metrology Institutes (NMIs) signed in 1999, an international comparison of spectral

Approaches to color rendering measurement

July 15, 2009
Author(s)
Wendy L. Davis, Yoshihiro Ohno
Color rendering refers to a light source’s ability to make the colors of illuminated objects appear natural or accurate. The Color Rendering Index (CRI) is currently the only internationally-standardized way to assess a light source’s color rendering

Extension of the NIST tristimulus colorimeter for solid-state light source measurements

May 29, 2009
Author(s)
George P. Eppeldauer, Carl C. Miller, Thomas C. Larason, Yoshihiro Ohno
In order to obtain improved color measurement uncertainties for solid state light (SSL) sources, the second generation tristimulus colorimeter of NIST has been extended with a fifth channel to perform efficient matrix corrections for the spectral mismatch

NIST SPECTRALLY TUNABLE LIGHTING FACILITY FOR COLOR RENDERING AND LIGHTING EXPERIMENTS

May 29, 2009
Author(s)
Carl C. Miller, Yoshihiro Ohno, Wendy L. Davis, Yuqin Zong, Kevin Dowling
The National Institute of Standards and Technology has developed a spectrally tunable lighting facility to allow state-of-the-art vision experiments on color rendering and lighting. The facility is composed of two cubicles, each lit by a spectrally tunable

Standardization Activities for Solid State Lighting in the USA

May 29, 2009
Author(s)
Yoshihiro Ohno
In support of the U.S. Department Energy s Energy Star program for solid state lighting, a series of standards for solid state lighting products have been developed in the USA. The standards published related to measurement and color include ANSI-NEMA

f1' EVALUATION AND MEASUREMENT COMPARISON

October 1, 2008
Author(s)
Jiangen PAN, Haiping SHEN, Yuqin Zong, Yoshi Ohno
The mismatch of spectral responsivity to the CIE V(lambda) function, i. e., the f1' index, is the most critical characteristic of photometers and tristimulus colorimeters. The f1' value varies with measurement conditions, which is often omitted in the f1'

NEW PRACTICAL METHOD FOR MEASUREMENT OF HIGH-POWER LEDS

October 1, 2008
Author(s)
Yuqin Zong, Yoshihiro Ohno
The measurement of high-power light emitting diodes (LEDs) has been difficult because they are highly sensitive to thermal operating conditions, and there has been a lack of common methods that can be used by both LED manufactures and users to acquire

Detector-based calibration procedures for tristimulus colorimeter standards

September 15, 2008
Author(s)
George P. Eppeldauer, Carl C. Miller, Yoshihiro Ohno
Two reference and three working standard tristimulus colorimeters have been developed at the National Institute of Standards and Technology (NIST) to utilize the recently introduced detector based colorimeter calibration method [1]. The tristimulus

PRACTICAL METHOD FOR MEASUREMENT OF AC-DRIVEN HIGH-POWER LEDS

July 14, 2008
Author(s)
Yuqin Zong, Yoshihiro Ohno, Pei-ting Chou
Alternating-current (AC) driven high-power LEDs are available and used in SSL products. AC LEDs operate directly from a mains supply and thus have advantages in simplifying product design, increasing product reliability, and extending product lifetime

Color Quality and Spectra

July 1, 2008
Author(s)
Yoshihiro Ohno, Wendy L. Davis
Color quality, including white light chromaticity and color rendering performance, as well as luminous efficacy of radiation, for illumination sources are introduced. Spectral design considerations for white LED and solid-state lighting products to achieve

Color Rendering

July 11, 2007
Author(s)
Yoshihiro Ohno
LED technologies are advancing at a swift pace and solid-state lighting (SSL) products are already introduced to the market and expected to grow rapidly. There is an increasing interest and concern in the color rendering properties of white SSL products