WO2010068269A1 - Écran rétroéclairé - Google Patents

Écran rétroéclairé Download PDF

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Publication number
WO2010068269A1
WO2010068269A1 PCT/US2009/006485 US2009006485W WO2010068269A1 WO 2010068269 A1 WO2010068269 A1 WO 2010068269A1 US 2009006485 W US2009006485 W US 2009006485W WO 2010068269 A1 WO2010068269 A1 WO 2010068269A1
Authority
WO
WIPO (PCT)
Prior art keywords
electrowetting
display
layer
pixel
illumination
Prior art date
Application number
PCT/US2009/006485
Other languages
English (en)
Inventor
John Richard Fyson
Original Assignee
Eastman Kodak Company
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Eastman Kodak Company filed Critical Eastman Kodak Company
Publication of WO2010068269A1 publication Critical patent/WO2010068269A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/004—Optical devices or arrangements for the control of light using movable or deformable optical elements based on a displacement or a deformation of a fluid
    • G02B26/005—Optical devices or arrangements for the control of light using movable or deformable optical elements based on a displacement or a deformation of a fluid based on electrowetting

Definitions

  • This invention relates to a display or indicating device which is provided with backlighting, in particular to electroluminescent devices.
  • electroluminescent devices that rely on the electroluminescence. This is a general term for an optical phenomenon and electrical phenomenon where a material emits light in response to an electric current passed through it, or to a strong electric field. This is distinct to light emission resulting from heat (incandescence) or from the action of chemicals (chemoluminescence). There are many types of this phenomenon such as OLEDS, PLEDS, thin film electroluminescence and AC electroluminescence.
  • this consists of a layer containing a phosphor powder suspended in a transparent dielectric (insulator) sandwiched between two electrodes, at least one of which is transparent.
  • This conductor is usually a thin evaporated doped tin oxide layer on a transparent support such as glass or plastic.
  • the amount of light given out from the device is controlled by applying an alternating voltage between the electrodes. If a pixellated device such as a display is required, at least one of the electrodes is segmented such that each element can be controlled.
  • Basic electrowetting displays are known in the art.
  • a basic electrowetting optical element is described in EP 1069450.
  • This document discloses an optical element having a first fluid and an electro-conductive second fluid.
  • the fluids are immiscible with each other and confined in a sealed space.
  • the first and second fluids have different light transmittances.
  • By varying a voltage applied to the second fluid the shape of the interface between the two fluids is changed. This voltage can be alternating.
  • the amount of light passing through the element can thus be changed.
  • a further refinement to this concept using said optical element to create a pixel as part of an electrowetting display device is described in WO2004/ 104670. If a pixilated device such as a display is required, at least one of the electrodes is segmented such that each element can be controlled.
  • LCD elements can control the amount of light passing through an element. This is also controlled by changing the AC electric field applied.
  • Electrowetting and LCD displays have a relatively low contrast unless they are illuminated from behind. In reflection mode the base density and the absorption of the liquid crystal or the electrowetting liquids define the maximum and minimum reflectivity of the pixels in the device. In brightly lit conditions such as bright daylight this may be sufficient.
  • the illumination can be from behind. Also if the contrast must be increased the contrast is dependent on the brightness of the illuminant as well as the adsorption of LCD or electrowetting component. If the backlight is turned on over the whole area of a device, energy is wasted by illuminating areas where light is to be absorbed as well as lit areas as well as 'leaking' through the LED or electrowetting element reducing the contrast.
  • a display By careful choice of architecture of a device a display can be constructed which has a number of luminescent elements and light modulating elements which are in register and are controlled by the same (AC) voltage. Application of the AC voltage causes the electroluminescent material to glow and the light modulator to allow more light through.
  • the cell In the case of an electrowetting modulator, the cell can be designed such that the electroluminescent material will glow brighter under the conducting fluid than under the non-conducting liquid in a two liquid cell because the electric field is reduced under the non-conducting liquid.
  • a display or indicating device having at least one pixel wherein each pixel is provided with electrodes which are adapted to simultaneously provide power to an illumination element and control to an electrowetting element.
  • the device of the invention saves power since the ACEL can be turned off during the day when it is not required. Only the area under the pixel is illuminated which also saves power.
  • the device is easy to manufacture. Only one substrate is used with the layers being coated in one set of coating processes.
  • the phosphor acts as a white scattering layer under the electrowetting cell which is an advantage in high light conditions when the backlight is not good.
  • the contrast of the image is higher as the uncovered layer glows more than the reflected light and there is now light under the dark area of the electrowetting oil that is pushed aside.
  • Figure 1 is a schematic view of the layer structure of a pixel element
  • Figures 2a and 2b illustrate the "on” and "off state of an element
  • FIG. 3 is a schematic view of a device according to the invention. DETAILED DESCRIPTION OF THE INVENTION
  • the layer structure of a pixel element is shown in Figure 1. It illustrates the structure of a possible coating for use as a combination of ACEL and electrowetting elements.
  • the coating consists of a base 70.
  • the base may be opaque or transparent, conducting or otherwise. If the base 70 is not conducting a conducting layer 50, such as doped tin oxide or an organic conductor such as polythiophen, is coated onto it by a method appropriate to the material being coated.
  • a layer 40 comprising a dielectric compound in which is dispersed an ECEL phosphor is coated onto layer 50, or layer 70 if layer 50 is not required.
  • a layer 30 which exhibits electrowetting behaviour is coated above layer 40.
  • An example of this layer is a polyfluorinated hydrocarbon. It will be understood by those skilled in the art that any appropriate material exhibiting electrowetting behaviour may be used for layer 30.
  • Figure 2a illustrates the "on” state of the element.
  • Figure 2b illustrates the "off state.
  • the coating as described with respect to Figure 1 is used, i.e. having layers 30, 40, 50 and 70.
  • a droplet 20 of, for example, 2M potassium chloride solution is provided above the layer 30. This liquid sits on the surface.
  • the liquid can be any conducting solution or conducting liquid that does not attack the polyfluorinatedhydrocarbon. This could be an ionic liquid.
  • the liquid should be conducting, mobile and non-viscous.
  • the diameter of the droplet is between about lmm and 10mm.
  • a syringe needle 10 Into this is inserted a syringe needle 10.
  • the syringe needle and the conducting substrate 50 are connected to a 40Ov AC power supply 60 (IkHz).
  • the power supply 60 is switched off. As there is no electric field the phosphor 45 within the layer 40 does not glow. The wetting angle of the droplet 20 does not change and the size of the droplet does not change.
  • the device illustrated in Figure 3 is based on the coating described in Figure 1, i.e. having layers 30, 40, 50 and 70.
  • a plastic well 10 was stuck onto the coating with Vaseline. The plastic well was made by stamping a 6mm hole in a piece of 200 micron plastic shim. The well was filled with conducting fluid, 2M KCl solution 20. About 0.5 microlitres of 0.1 M Oil Blue N in n-decane 100 was injected into the conducting fluid. This liquid must be non conducting and immiscible with the conducting liquid.
  • Example 1 A coating was made as follows with reference to Figures 2a and
  • the coating was made on CPfilmsTM CP300 indium tin oxide, 50, on heat stabilised PET, 70.
  • a mixture of 2g RadiosparesTM polyurethane potting compound (made as instructed 5:2 by weight) and 5g Durel 1PHS002AA blue- green ACEL phosphor was bar coated using a 100 micron bar at a very slow speed. This layer 40 was allowed to set at 65°C in a hotbox oven for 24 hours. Over this was coated a 12 micron layer 30 of 4% Teflon AF 1600 dissolved in Fluorinert FC-75.
  • Example 2 A device was made as described in Figure 3. When there was no voltage applied the phosphor did not glow and the oil blue N solution 100 covered the bottom of the well. On applying the voltage the oil blue N solution contracted leaving 60% of the bottom of the well uncovered and the ACEL phosphor glowing only under the exposed area.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)

Abstract

La présente invention concerne un écran ou un indicateur comportant au moins un pixel, chaque pixel étant pourvu d'électrodes conçues pour pouvoir alimenter en électricité un élément d'éclairage tout en commandant un élément d'électromouillage.
PCT/US2009/006485 2008-12-13 2009-12-10 Écran rétroéclairé WO2010068269A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0822756.3 2008-12-13
GB0822756A GB0822756D0 (en) 2008-12-13 2008-12-13 Backlit display

Publications (1)

Publication Number Publication Date
WO2010068269A1 true WO2010068269A1 (fr) 2010-06-17

Family

ID=40326062

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2009/006485 WO2010068269A1 (fr) 2008-12-13 2009-12-10 Écran rétroéclairé

Country Status (2)

Country Link
GB (1) GB0822756D0 (fr)
WO (1) WO2010068269A1 (fr)

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1069450A2 (fr) 1999-06-16 2001-01-17 Canon Kabushiki Kaisha Elément optique et dispositif optique comprenant ledit élément
WO2003048849A1 (fr) 2001-12-05 2003-06-12 Koninklijke Philips Electronics N.V. Dispositif d'affichage comprenant des elements d'affichage empiles, transmissifs et electroluminescents
WO2004104670A1 (fr) 2003-05-22 2004-12-02 Koninklijke Philips Electronics N.V. Dispositif d'affichage
WO2007071904A1 (fr) * 2005-12-22 2007-06-28 Eastman Kodak Company Dispositifs d’affichage
WO2008053144A1 (fr) * 2006-10-31 2008-05-08 Eastman Kodak Company Eléments d'affichage

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1069450A2 (fr) 1999-06-16 2001-01-17 Canon Kabushiki Kaisha Elément optique et dispositif optique comprenant ledit élément
WO2003048849A1 (fr) 2001-12-05 2003-06-12 Koninklijke Philips Electronics N.V. Dispositif d'affichage comprenant des elements d'affichage empiles, transmissifs et electroluminescents
WO2004104670A1 (fr) 2003-05-22 2004-12-02 Koninklijke Philips Electronics N.V. Dispositif d'affichage
WO2007071904A1 (fr) * 2005-12-22 2007-06-28 Eastman Kodak Company Dispositifs d’affichage
WO2008053144A1 (fr) * 2006-10-31 2008-05-08 Eastman Kodak Company Eléments d'affichage

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
ROQUES-CARMES THIBAULT ET AL: "Liquid behavior inside a reflective display pixel based on electrowetting", JOURNAL OF APPLIED PHYSICS, AMERICAN INSTITUTE OF PHYSICS. NEW YORK, US LNKD- DOI:10.1063/1.1667595, vol. 95, no. 8, 15 April 2004 (2004-04-15), pages 4389 - 4396, XP012067801, ISSN: 0021-8979 *

Also Published As

Publication number Publication date
GB0822756D0 (en) 2009-01-21

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