Return-Path: X-Original-To: u7f01aa@mail.lrz-muenchen.de Delivered-To: u7f01aa@mail.lrz-muenchen.de Received: from mailrelay1.lrz-muenchen.de (mailrelay1.lrz-muenchen.de [129.187.254.106]) by mailin.lrz-muenchen.de (Postfix) with ESMTP id 9E9316A9D4 for ; Thu, 19 Feb 2009 18:42:54 +0100 (CET) Received: from lxmhs13.lrz-muenchen.de (lxmhs13.lrz-muenchen.de [10.156.6.206]) by mailrelay1.lrz-muenchen.de with ESMTP for Hans.Strasburger@lrz.uni-muenchen.de; Thu, 19 Feb 2009 18:42:53 +0100 Received: from mailrelay2.lrz-muenchen.de (mailrelay2.lrz-muenchen.de [10.156.6.1]) by lxmhs13.lrz-muenchen.de (Postfix) with ESMTP id D825980A239 for ; Thu, 19 Feb 2009 18:42:53 +0100 (CET) Received: from lxmhs39.lrz-muenchen.de (lxmhs39.lrz-muenchen.de [10.156.6.25]) by mailrelay2.lrz-muenchen.de with ESMTP for strasburger@uni-muenchen.de; Thu, 19 Feb 2009 18:42:47 +0100 X-Virus-Scanned: by amavisd-new at lrz-muenchen.de in 39 X-Spam-Flag: NO X-Spam-Score: 0.008 X-Spam-Level: X-Spam-Status: No, score=0.008 tagged_above=-999 required=5 tests=[BAYES_50=0.001, HTML_MESSAGE=0.001, LRZ_FROM_PRE_SURa=0.001, LRZ_HAS_IN_REPLY_TO=0.001, LRZ_HAS_SENDER=0.001, LRZ_MSGID_FROM_DOMAIN=0.001, LRZ_TO_SHORT=0.001, MIME_HTML_MOSTLY=0.001] autolearn=disabled Received: from mailrelay1.lrz-muenchen.de ([10.156.6.201]) by lxmhs39.lrz-muenchen.de (lxmhs39.lrz-muenchen.de [10.156.6.25]) (amavisd-new, port 10024) with ESMTP id eBa6b1b-CgbO for ; Thu, 19 Feb 2009 18:42:46 +0100 (CET) Received: from postrelay1.lrz-muenchen.de ([10.156.6.9] [10.156.6.9]) by mailrelay1.lrz-muenchen.de with ESMTP for strasburger@uni-muenchen.de; Thu, 19 Feb 2009 18:42:46 +0100 Received: from visionscience.com (visionscience.com [128.121.79.28]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by postrelay1.lrz-muenchen.de (Postfix) with ESMTPS id 2244C2400066 for ; Thu, 19 Feb 2009 18:42:44 +0100 (CET) Received: from abwatson1.best.vwh.net (localhost [127.0.0.1]) by visionscience.com (8.13.6.20060614/8.13.6) with ESMTP id n1JG5vSg057924; Thu, 19 Feb 2009 08:29:29 -0800 (PST) Received: from ndmsnpf01.ndc.nasa.gov (ndmsnpf01.ndc.nasa.gov [198.117.0.121]) by visionscience.com (8.13.6.20060614/8.13.6) with ESMTP id n1JG58Ao057586 for ; Thu, 19 Feb 2009 08:05:08 -0800 (PST) Received: from ndjsppt03.ndc.nasa.gov (ndjsppt03.ndc.nasa.gov [198.117.1.102]) by ndmsnpf01.ndc.nasa.gov (Postfix) with ESMTP id E293626016F; Thu, 19 Feb 2009 10:05:04 -0600 (CST) Received: from ndjsxgw04.ndc.nasa.gov (ndjsxgw04.ndc.nasa.gov [129.166.32.112]) by ndjsppt03.ndc.nasa.gov (8.14.1/8.14.1) with ESMTP id n1JG56gH007067; Thu, 19 Feb 2009 10:05:06 -0600 Received: from smtp01.ndc.nasa.gov ([129.166.32.112]) by ndjsxgw04.ndc.nasa.gov with Microsoft SMTPSVC(6.0.3790.3959); Thu, 19 Feb 2009 10:05:04 -0600 Received: from [10.0.1.196] ([129.166.32.16]) by smtp01.ndc.nasa.gov over TLS secured channel with Microsoft SMTPSVC(6.0.3790.3959); Thu, 19 Feb 2009 10:05:03 -0600 Message-Id: From: Andrew Watson To: visionlist@visionscience.com In-Reply-To: <49F30984-7983-440F-87C0-11566FF17994@psych.usyd.edu.au> Mime-Version: 1.0 (Apple Message framework v930.3) Subject: Re: [visionlist] LED monitors Date: Thu, 19 Feb 2009 08:05:00 -0800 References: <96F77944E1BA554D814FBC549EC5D3F0064E4FDC@moonraker.campus.ncl.ac.uk> <49F30984-7983-440F-87C0-11566FF17994@psych.usyd.edu.au> X-Mailer: Apple Mail (2.930.3) X-OriginalArrivalTime: 19 Feb 2009 16:05:04.0467 (UTC) FILETIME=[D3A57A30:01C992AB] X-Mailman-Approved-At: Thu, 19 Feb 2009 08:05:55 -0800 Cc: X-BeenThere: visionlist@visionscience.com X-Mailman-Version: 2.1.5 Precedence: list List-Id: Vision Science Mailing List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============0118272448==" Sender: visionlist-bounces@visionscience.com Errors-To: visionlist-bounces@visionscience.com --===============0118272448== Content-Type: multipart/alternative; boundary=Apple-Mail-16--945737158 --Apple-Mail-16--945737158 Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Deborah, Below is a section of a displays standards document that Louis Silverstein and I wrote about LED displays. I hope it is helpful. OLED displays may well be useful in psychophysics, though I have not tried them yet myself. I believe they are used in some off-the-shelf adaptive optics systems from Imagine Eyes (http://www.imagine-eyes.com/). Andrew B. Watson Senior Scientist for Vision Research NASA Ames Research Center Moffett Field, CA 94035-1000 (650) 604-5419 1.1.1.1 Light-Emitting Diodes (LEDs) and Organic Light-Emitting Diodes (OLEDs) The LED is a semiconductor device consisting of a single p-n junction; light is emitted when the junction is forward biased by the application of a suitable voltage. The first commercially available LEDs were introduced into the marketplace in 1968 and quickly became an important technology for indicator lamps and small segmented alphanumeric displays. LEDs are now capable of producing a full spectrum of colors with very high color saturation and good luminous efficiency. Nevertheless, relatively high cost, interconnect complexity and manufacturing limitations in building high-density arrays of full- color LEDs have restricted their usage primarily to very large displays for digital signage and electronic billboard applications. Organic LEDs (OLEDs) and polymer LEDs (PLEDs) are LEDs whose emissive electroluminescent layer consists of a film of organic compounds (Bulovic, 2005; King, 1994). These films emit light when subjected to an electric current. The SPD of the emitted light depends on the type of organic molecule in the emissive layer. Full-color OLEDs are generally achieved by either spatial patterning of R, G and B emissive materials or by use of a broad-band emissive material in conjunction with a spatial pattern of R, G, and B color selection filters. The intensity of the emitted light depends on the amount of electrical current applied. The nonlinear relationship between voltage and current provides OLEDs with a nonlinear transfer function which is well characterized by a power function. Claimed advantages for OLEDs include: simplified manufacturing structure; compatibility with flexible substrates; lower manufacturing costs than LCDs or PDPs; high contrast with true black level; high luminance with good luminous efficiency; low power consumption; fast temporal response; wide viewing angle; and excellent grayscale performance (Bulovic, 2005; Ghosh & Hack, 2004). The principal disadvantages include limited lifetime of OLED and PLED emissive materials, lack of a stable short-wavelength emissive material with good lifetime, differential aging of emissive materials with different SPDs and susceptibility to contamination and damage from moisture. In addition, reflections from metal cathodes and other metallic structures within these devices can result in high levels of internal specular reflection under ambient illumination with commensurate degradations of ambient contrast. Circular polarizers may be used to mitigate these reflections, but their use dramatically reduces the luminous efficiency of the display. OLED and PLED display technologies remain in a very active state of development with a great deal of ongoing research on OLED / PLED materials, display system architectures and manufacturing processes. To date only a few small, mobile display products using OLEDs and PLEDs have appeared and stayed on the market. Display Technology Attributes General Rating Comments Spatial Addressability Spatial Resolution High High -Spatial resolution can be enhanced by vertically stacked color pixel structure Temporal Response Medium to High -Native response in sub-millisecond range -Temporal aperture extended by sample-and-hold mode of operation in active-matrix configurations Luminance Medium to High -Material dependent -Use of circular polarizer to enhance ambient contrast reduces luminance Contrast Ambient Contrast High Low to Medium -Excellent black levels -Specular reflectance from metal cathode limits ambient contrast -Circular polarizer can be used to enhance ambient contrast Grayscale Performance Very High -Continuous analog grayscale capability -transfer function a true power function Viewing Angle Very High -Effectively Lambertian viewing -Contrast enhancement filters can attenuate luminance off axis Color Gamut Ambient Color Gamut High Low to Medium -Color gamut defined by OLED / PLED materials -Specular reflections from metal cathode reduces color gamut under ambient -Circular polarizer can be used to enhance ambient color gamut Physical Package Very High -Very small footprint & light weight -Very small depth required Application Flexibility Very high -Very amenable to portable or battery-powered applications -Great flexibility in screen sizes Other -Prone to internal specular reflections under ambient -Circular polarizer reduces luminance -Differential aging of color materials can cause color shifts over time -Active-matrix configurations prone to motion blur with dynamic imagery Table 6. OLED / PLED Technology Attribute Ratings and Comments On Feb 18, 2009, at 5:36 PM, Deborah Apthorp wrote: > Hi, > > Does anyone know anything about the use of LED (NOT LCD) monitors > for psychophysics? I am not sure if there are any available yet with > a high enough refresh rate, but it seems as if potentially these > could be very useful for vision research. I can't find much about > them via Google so I wondered if anyone else in the vision community > is exploring these possibilities. > > Thanks, > > Deborah Apthorp > > (University of Sydney, Australia) > _______________________________________________ > visionlist mailing list > visionlist@visionscience.com > http://visionscience.com/mailman/listinfo/visionlist --Apple-Mail-16--945737158 Content-Type: text/html; charset=US-ASCII Content-Transfer-Encoding: quoted-printable
Deborah,

Below is a section of a displays = standards document that Louis Silverstein and I wrote about LED = displays.
I hope it is helpful.

OLED displays may well = be useful in psychophysics, though I have not tried them yet = myself.
I believe they are used in some = off-the-shelf adaptive optics systems from Imagine Eyes  (http://www.imagine-eyes.com/).

Andrew = B. Watson
Senior Scientist for Vision = Research
NASA Ames Research Center
Moffett Field, CA 94035-1000
(650) = 604-5419


1.1.1.1The LED is a semiconductor device = consisting of a single p-n junction;  light is = emitted when the junction is forward biased by the application of a = suitable voltage. The first commercially available LEDs were introduced = into the marketplace in 1968 and quickly became an important technology = for indicator lamps and small segmented alphanumeric = displays. 

 LEDs are now capable of producing = a full spectrum of colors with very high color saturation and good = luminous efficiency.  Nevertheless, relatively = high cost, interconnect complexity and manufacturing limitations in = building high-density arrays of full-color LEDs have restricted their = usage primarily to very large displays for digital signage and = electronic billboard applications. 

Organic LEDs (OLEDs) and polymer LEDs = (PLEDs) are LEDs whose emissive electroluminescent layer consists of a = film of organic compounds (Bulovic, 2005; King, = 1994).  These films emit light when subjected to = an electric current. The SPD of the emitted light depends on the type of = organic molecule in the emissive = layer.  Full-color OLEDs are generally achieved = by either spatial patterning of R, G and B emissive materials or by use = of a broad-band emissive material in conjunction with a spatial pattern = of R, G, and B color selection filters.  The = intensity of the emitted light depends on the amount of electrical = current applied.  The nonlinear relationship = between voltage and current provides OLEDs with a nonlinear transfer = function which is well characterized by a power = function.

 Claimed advantages for OLEDs = include:  simplified manufacturing structure; = compatibility with flexible substrates; lower manufacturing costs than = LCDs or PDPs; high contrast with true black level; high luminance with = good luminous efficiency; low power consumption; fast temporal response; = wide viewing angle; and excellent grayscale performance (Bulovic, = 2005; Ghosh & Hack, 2004).  The principal = disadvantages include limited lifetime of OLED and PLED emissive = materials, lack of a stable short-wavelength emissive material with good = lifetime, differential aging of emissive materials with different SPDs = and susceptibility to contamination and damage from = moisture.  In addition, reflections from metal = cathodes and other metallic structures within these devices can result = in high levels of internal specular reflection under ambient = illumination with commensurate degradations of ambient = contrast.  Circular polarizers may be used to = mitigate these reflections, but their use dramatically reduces the = luminous efficiency of the display.

OLED and PLED display technologies remain in a very = active state of development with a great deal of ongoing research on = OLED / PLED materials, display system architectures and manufacturing = processes.  To date only a few small, mobile = display products using OLEDs and PLEDs have appeared and stayed on the = market. 

 

Display Technology = Attributes

General Rating

Comments

Spatial Addressability

Spatial Resolution

High

High

-Spatial resolution can be enhanced by = vertically stacked color pixel structure

Temporal Response

Medium to High

-Native response in sub-millisecond = range

-Temporal aperture = extended by sample-and-hold mode of operation in active-matrix = configurations

Luminance

Medium to High

 

-Material dependent

-Use of circular polarizer to enhance = ambient contrast reduces luminance

Contrast

Ambient Contrast

High

Low to Medium

-Excellent black levels

-Specular reflectance from metal cathode = limits ambient contrast

-Circular polarizer can be used to enhance ambient = contrast

Grayscale Performance

Very High

-Continuous analog grayscale = capability

-transfer = function a true power function

Viewing Angle

Very High

 

-Effectively Lambertian = viewing

-Contrast = enhancement filters can attenuate luminance off = axis

Color Gamut

Ambient Color Gamut

High

Low to Medium

-Color gamut defined by OLED / PLED = materials

-Specular = reflections from metal cathode reduces color gamut under = ambient

-Circular = polarizer can be used to enhance ambient color = gamut

Physical Package

Very High

-Very small footprint & light = weight

-Very small depth = required

Application Flexibility

Very high

-Very amenable to portable or = battery-powered applications

-Great flexibility in screen = sizes

Other

 

-Prone to internal specular reflections = under ambient

-Circular = polarizer reduces luminance

-Differential aging of color materials can cause = color shifts over time

-Active-matrix configurations prone to motion blur = with dynamic imagery

Table 6. OLED / PLED Technology = Attribute Ratings and Comments

On Feb 18, 2009, = at 5:36 PM, Deborah Apthorp wrote:

Hi,

Does anyone know anything about the use of = LED (NOT LCD) monitors for psychophysics? I am not sure if there are any = available yet with a high enough refresh rate, but it seems as if = potentially these could be very useful for vision research. I can't find = much about them via Google so I wondered if anyone else in the vision = community is exploring these = possibilities.

Thanks,

Deborah Apthorp

(University = of Sydney, = Australia)
_______________________________________________
visionlis= t mailing list
visionlist@visionscience.com<= /a>
http://visionscience.com/mailman/listinfo/visionlist

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