EP0072827A1 - Display device - Google Patents

Display device

Info

Publication number
EP0072827A1
EP0072827A1 EP82900555A EP82900555A EP0072827A1 EP 0072827 A1 EP0072827 A1 EP 0072827A1 EP 82900555 A EP82900555 A EP 82900555A EP 82900555 A EP82900555 A EP 82900555A EP 0072827 A1 EP0072827 A1 EP 0072827A1
Authority
EP
European Patent Office
Prior art keywords
particles
display device
suspension medium
glass
spheres
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP82900555A
Other languages
German (de)
French (fr)
Inventor
Peter John Bassett
Augustine Wilhelmus Verheijen
Josephus Bonifacius Peeters
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SA Patscentre Benelux Nv
Original Assignee
SA Patscentre Benelux Nv
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 SA Patscentre Benelux Nv filed Critical SA Patscentre Benelux Nv
Publication of EP0072827A1 publication Critical patent/EP0072827A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/165—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field
    • G02F1/166—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field characterised by the electro-optical or magneto-optical effect
    • G02F1/167—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on translational movement of particles in a fluid under the influence of an applied field characterised by the electro-optical or magneto-optical effect by electrophoresis
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03G—ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
    • G03G17/00—Electrographic processes using patterns other than charge patterns, e.g. an electric conductivity pattern; Processes involving a migration, e.g. photoelectrophoresis, photoelectrosolography; Processes involving a selective transfer, e.g. electrophoto-adhesive processes; Apparatus essentially involving a single such process
    • G03G17/04—Electrographic processes using patterns other than charge patterns, e.g. an electric conductivity pattern; Processes involving a migration, e.g. photoelectrophoresis, photoelectrosolography; Processes involving a selective transfer, e.g. electrophoto-adhesive processes; Apparatus essentially involving a single such process using photoelectrophoresis

Definitions

  • the present invention relates to display devices and more particularly to electrophoretic or dielectricphoretic display devices.
  • Electrophoretic display devices are known and a feature of these devices is that they are passive, i.e. they do not emit light rather they reflect or transmit incident light.
  • An object of the present invention is to provide an electrophorectic or dielectricphoretic display device with enhanced reflectance in the direction of illumination.
  • An electrophoretic display device 10 comprises a non-conductive substrate 11 to which is applied an electrode 12 and an electrode 13 spaced from the electrode 12.
  • the space between the electrode 12 and the electrode 13 is filled by a liquid material 15 containing small particles 16.
  • a liquid material 15 containing small particles 16 When an electric field is applied across the space by a voltage applied to the electrode 12 and electrode 13, the particles migrate to either the electrode 12 or the olectrodo 13.
  • Either or both of the electrodes 12, 13 can be an array so as to produce any desired pattern depending on the disposition and shape of the or each array.
  • the device is designed for viewing in the direction of the arrow A in which case the electrode 13 will be formed of a transparent material and provided with a transparent protective cover 17.
  • the particles 16 are specifically selected for their reflective properties and it has been found that they should be optically transparent in at least part of the visible spectrum. Further, they should have a diameter similar to or larger than the wavelength of visible light, e.g. from 0.5 to 20 microns. It is advantageous if they have a specific gravity similar to that of the liquid material so that they exhibit neutral buoyancy in the liquid material and can move relatively easily under the action of an electric field.
  • glass or plastics particles being used.
  • a combination of glass and plastics is also possible such as glass coated with plastics.
  • the preferred plastics are polyamide, polyimide, polyester, polypropylene or polycarbonate.
  • the particles are spherical but may be either solid or hollow spheres.
  • the refractive index of the material of the spheres should preferably be higher than that of the liquid material. Such particles are known to exhibit good reflectance in the direction of illumination.
  • the electrophoretic activity can be enhanced by adding a surfactant to the liquid material and/or by forming electrets within the particles.
  • the above construction may be used as an addressable sign such as a road sign, a warning display or an information panel and has the additional advantages that dye absorption on reflective glass particles would be lower than absorption on conventional organic pigments. This provides increased perceived contrast. Also, chemical and light-induced degradation is lower for glass particles than for organic pigments. Thus, the life of the device would be increased.
  • glass particles With glass particles, it may be necessary to process them so that they exhibit an electrophoretic effect.
  • a number of processes are available such as exposing molten glass to an electrical discharge and cooling the glass to trap charged particles in the glass matrix.
  • glass at .room temperature could be exposed to ionizing radiation such as cathode rays or X-rays to form charged particles in the glass. Both these processes form electrets but it is also possible to activate the surface of the glass particles chemically and then coat the particles with long chain molecules to cause a charge to be present.

Landscapes

  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Molecular Biology (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)

Abstract

Un dispositif d'affichage a electrophorese utilise des spheres transparentes (16) dont le diametre est de l'ordre de grandeur de la longueur d'onde de la lumiere visible au lieu des particules de pigment conventionnelles, ce qui accroit l'effet retro-reflechissant du dispositif. Les spheres (16) peuvent etre en verre ou en plastique ou bien une combinaison des deux et presentent une gravite specifique semblable a celle du milieu de suspension quiles contient.An electrophoresis display device uses transparent spheres (16) whose diameter is on the order of magnitude of the wavelength of visible light instead of conventional pigment particles, which increases the retro effect. reflective device. The spheres (16) can be glass or plastic or a combination of the two and exhibit a specific gravity similar to that of the suspension medium which they contain.

Description

DISPLAY DEVICE
The present invention relates to display devices and more particularly to electrophoretic or dielectricphoretic display devices.
Electrophoretic display devices are known and a feature of these devices is that they are passive, i.e. they do not emit light rather they reflect or transmit incident light.
An object of the present invention is to provide an electrophorectic or dielectricphoretic display device with enhanced reflectance in the direction of illumination.
In order that the present invention be more readily understood, an embodiment thereof will now be described by way of example with reference to the accompanying drawing which shows a cross-section through an electrophoretic display device. An electrophoretic display device 10 comprises a non-conductive substrate 11 to which is applied an electrode 12 and an electrode 13 spaced from the electrode 12. The space between the electrode 12 and the electrode 13 is filled by a liquid material 15 containing small particles 16. When an electric field is applied across the space by a voltage applied to the electrode 12 and electrode 13, the particles migrate to either the electrode 12 or the olectrodo 13. Either or both of the electrodes 12, 13 can be an array so as to produce any desired pattern depending on the disposition and shape of the or each array.
In this embodiment, the device is designed for viewing in the direction of the arrow A in which case the electrode 13 will be formed of a transparent material and provided with a transparent protective cover 17.
The particles 16 are specifically selected for their reflective properties and it has been found that they should be optically transparent in at least part of the visible spectrum. Further, they should have a diameter similar to or larger than the wavelength of visible light, e.g. from 0.5 to 20 microns. It is advantageous if they have a specific gravity similar to that of the liquid material so that they exhibit neutral buoyancy in the liquid material and can move relatively easily under the action of an electric field.
These two desiderata point to glass or plastics particles being used. A combination of glass and plastics is also possible such as glass coated with plastics. The preferred plastics are polyamide, polyimide, polyester, polypropylene or polycarbonate.
Preferably the particles are spherical but may be either solid or hollow spheres. The refractive index of the material of the spheres should preferably be higher than that of the liquid material. Such particles are known to exhibit good reflectance in the direction of illumination.
The electrophoretic activity can be enhanced by adding a surfactant to the liquid material and/or by forming electrets within the particles.
The above construction may be used as an addressable sign such as a road sign, a warning display or an information panel and has the additional advantages that dye absorption on reflective glass particles would be lower than absorption on conventional organic pigments. This provides increased perceived contrast. Also, chemical and light-induced degradation is lower for glass particles than for organic pigments. Thus, the life of the device would be increased.
With glass particles, it may be necessary to process them so that they exhibit an electrophoretic effect. A number of processes are available such as exposing molten glass to an electrical discharge and cooling the glass to trap charged particles in the glass matrix. Alternatively, glass at .room temperature could be exposed to ionizing radiation such as cathode rays or X-rays to form charged particles in the glass. Both these processes form electrets but it is also possible to activate the surface of the glass particles chemically and then coat the particles with long chain molecules to cause a charge to be present.

Claims

CLAIMS :
1. A display device comprising spaced electrodes and electrophoretically active particles in a liquid suspension medium disposed between said electrodes, the particles having a refractive index greater than that of the suspension medium characterised in that the particles are transparent to light in at least part of the visible spectrum and have an external diameter similar to or larger than the wavelength of visible light.
2. A display device according to claim 1, characterised in that the particles are spheres and are of glass or plastics materials or a combination thereof.
3. A display device according to claim 1 or 2 , characterised in that the particles are hollow.
4. A display device according to claim 1, 2 or 3 , characterised in that the particles have a specific gravity similar to that of the suspension medium.
5. A display device according to any one of the preceding claims characterised in that the particles include electretsto enhance the electrophoretic activity.
6. A display device according to any one of the preceding claims, characterised in that the liquid suspension medium includes a surfactant to enhance the electrophoretic activity.
EP82900555A 1981-02-24 1982-02-23 Display device Withdrawn EP0072827A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8105802 1981-02-24
GB8105802 1981-02-24

Publications (1)

Publication Number Publication Date
EP0072827A1 true EP0072827A1 (en) 1983-03-02

Family

ID=10519926

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82900555A Withdrawn EP0072827A1 (en) 1981-02-24 1982-02-23 Display device

Country Status (2)

Country Link
EP (1) EP0072827A1 (en)
WO (1) WO1982002961A1 (en)

Families Citing this family (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6639578B1 (en) 1995-07-20 2003-10-28 E Ink Corporation Flexible displays
US6459418B1 (en) 1995-07-20 2002-10-01 E Ink Corporation Displays combining active and non-active inks
US6118426A (en) * 1995-07-20 2000-09-12 E Ink Corporation Transducers and indicators having printed displays
US5961804A (en) * 1997-03-18 1999-10-05 Massachusetts Institute Of Technology Microencapsulated electrophoretic display
US6252564B1 (en) 1997-08-28 2001-06-26 E Ink Corporation Tiled displays
EP1010035B1 (en) * 1997-08-28 2004-10-27 E Ink Corporation Novel addressing schemes for electrophoretic displays
US6825829B1 (en) 1997-08-28 2004-11-30 E Ink Corporation Adhesive backed displays
US8040594B2 (en) 1997-08-28 2011-10-18 E Ink Corporation Multi-color electrophoretic displays
ATE349722T1 (en) 1998-07-08 2007-01-15 E Ink Corp IMPROVED COLOR MICRO-ENCAPSULED ELECTROPHORETIC DISPLAY
US20050156340A1 (en) 2004-01-20 2005-07-21 E Ink Corporation Preparation of capsules
US6982178B2 (en) 2002-06-10 2006-01-03 E Ink Corporation Components and methods for use in electro-optic displays
US7382514B2 (en) 2002-02-11 2008-06-03 Sipix Imaging, Inc. Core-shell particles for electrophoretic display
TWI229115B (en) * 2002-02-11 2005-03-11 Sipix Imaging Inc Core-shell particles for electrophoretic display
US7843621B2 (en) 2002-06-10 2010-11-30 E Ink Corporation Components and testing methods for use in the production of electro-optic displays
US9470950B2 (en) 2002-06-10 2016-10-18 E Ink Corporation Electro-optic displays, and processes for the production thereof
US8363299B2 (en) 2002-06-10 2013-01-29 E Ink Corporation Electro-optic displays, and processes for the production thereof
US7839564B2 (en) 2002-09-03 2010-11-23 E Ink Corporation Components and methods for use in electro-optic displays
EP3056941B1 (en) 2002-09-03 2019-01-09 E Ink Corporation Electro-phoretic medium
US20080043318A1 (en) 2005-10-18 2008-02-21 E Ink Corporation Color electro-optic displays, and processes for the production thereof
TWI484275B (en) 2010-05-21 2015-05-11 E Ink Corp Electro-optic display, method for driving the same and microcavity electrophoretic display

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US2792752A (en) * 1953-07-01 1957-05-21 Rca Corp Method of and means for controlling light
NL232142A (en) * 1957-10-19 1966-05-16
US3954465A (en) * 1972-09-20 1976-05-04 Xerox Corporation Electrophoretic imaging members
US3782932A (en) * 1972-09-20 1974-01-01 Xerox Corp Electrophoretic imaging process using transparent particles
GB1442360A (en) * 1973-10-01 1976-07-14 Secr Defence Electro-optical device
US3972715A (en) * 1973-10-29 1976-08-03 Xerox Corporation Particle orientation imaging system
US4126528A (en) * 1977-07-26 1978-11-21 Xerox Corporation Electrophoretic composition and display device
EP0023741A1 (en) * 1979-08-02 1981-02-11 Koninklijke Philips Electronics N.V. Electrophoretic image display device

Non-Patent Citations (1)

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Title
See references of WO8202961A1 *

Also Published As

Publication number Publication date
WO1982002961A1 (en) 1982-09-02

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Legal Events

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PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

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Effective date: 19821028

AK Designated contracting states

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STAA Information on the status of an ep patent application or granted ep patent

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18D Application deemed to be withdrawn

Effective date: 19840410

RIN1 Information on inventor provided before grant (corrected)

Inventor name: VERHEIJEN, AUGUSTINE, WILHELMUS

Inventor name: PEETERS, JOSEPHUS BONIFACIUS

Inventor name: BASSETT, PETER JOHN