WO1982002961A1 - Display device - Google Patents

Display device Download PDF

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Publication number
WO1982002961A1
WO1982002961A1 PCT/GB1982/000059 GB8200059W WO8202961A1 WO 1982002961 A1 WO1982002961 A1 WO 1982002961A1 GB 8200059 W GB8200059 W GB 8200059W WO 8202961 A1 WO8202961 A1 WO 8202961A1
Authority
WO
WIPO (PCT)
Prior art keywords
particles
display device
suspension medium
glass
enhance
Prior art date
Application number
PCT/GB1982/000059
Other languages
French (fr)
Inventor
Benelux Nv Patscentre
Original Assignee
Bassett Peter John
Verheijen Augustine Wilhelmus
Peeters Josephus Bonifacius
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 Bassett Peter John, Verheijen Augustine Wilhelmus, Peeters Josephus Bonifacius filed Critical Bassett Peter John
Publication of WO1982002961A1 publication Critical patent/WO1982002961A1/en

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.

Abstract

An electrophoretic display device utilizes transparent spheres (16) whose diameter is similar to that of visible light in place of the conventional pigment particles whereby to enhance the retro-reflective effect of the device. The spheres (16) may be glass or plastics or a combination of both with a specific gravity similar to that of the suspension medium (15) in which they are contained.

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.
PCT/GB1982/000059 1981-02-24 1982-02-23 Display device WO1982002961A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8105802810224 1981-02-24
GB8105802 1981-02-24

Publications (1)

Publication Number Publication Date
WO1982002961A1 true WO1982002961A1 (en) 1982-09-02

Family

ID=10519926

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1982/000059 WO1982002961A1 (en) 1981-02-24 1982-02-23 Display device

Country Status (2)

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

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998041899A2 (en) * 1997-03-18 1998-09-24 Massachusetts Institute Of Technology Improved microencapsulated electrophoretic display
WO1999010767A1 (en) * 1997-08-28 1999-03-04 E-Ink Corporation Electrophoretic displays and materials
US6118426A (en) * 1995-07-20 2000-09-12 E Ink Corporation Transducers and indicators having printed displays
US6252564B1 (en) 1997-08-28 2001-06-26 E Ink Corporation Tiled displays
US6459418B1 (en) 1995-07-20 2002-10-01 E Ink Corporation Displays combining active and non-active inks
WO2003069403A1 (en) * 2002-02-11 2003-08-21 Sipix Imaging, Inc. Core-shell particles for electrophoretic display
US6639578B1 (en) 1995-07-20 2003-10-28 E Ink Corporation Flexible displays
US6825829B1 (en) 1997-08-28 2004-11-30 E Ink Corporation Adhesive backed displays
US7382514B2 (en) 2002-02-11 2008-06-03 Sipix Imaging, Inc. Core-shell particles for electrophoretic display
US8854721B2 (en) 2002-06-10 2014-10-07 E Ink Corporation Components and testing methods for use in the production of electro-optic displays
US9005494B2 (en) 2004-01-20 2015-04-14 E Ink Corporation Preparation of capsules
US9075280B2 (en) 2002-09-03 2015-07-07 E Ink Corporation Components and methods for use in electro-optic displays
US9170467B2 (en) 2005-10-18 2015-10-27 E Ink Corporation Color electro-optic displays, and processes for the production thereof
US9182646B2 (en) 2002-06-10 2015-11-10 E Ink Corporation Electro-optic displays, and processes for the production thereof
US9268191B2 (en) 1997-08-28 2016-02-23 E Ink Corporation Multi-color electrophoretic displays
US9293511B2 (en) 1998-07-08 2016-03-22 E Ink Corporation Methods for achieving improved color in microencapsulated electrophoretic devices
US9470950B2 (en) 2002-06-10 2016-10-18 E Ink Corporation Electro-optic displays, and processes for the production thereof
US9563099B2 (en) 2002-06-10 2017-02-07 E Ink Corporation Components and methods for use in electro-optic displays
US10444590B2 (en) 2002-09-03 2019-10-15 E Ink Corporation Electro-optic displays
US11733580B2 (en) 2010-05-21 2023-08-22 E Ink Corporation Method for driving two layer variable transmission display

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2792752A (en) * 1953-07-01 1957-05-21 Rca Corp Method of and means for controlling light
US3169163A (en) * 1957-10-19 1965-02-09 Agfa Ag Fa Electro-optical light valve utilizing charged particle migration
US3782932A (en) * 1972-09-20 1974-01-01 Xerox Corp Electrophoretic imaging process using transparent particles
US3954465A (en) * 1972-09-20 1976-05-04 Xerox Corporation Electrophoretic imaging members
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

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2792752A (en) * 1953-07-01 1957-05-21 Rca Corp Method of and means for controlling light
US3169163A (en) * 1957-10-19 1965-02-09 Agfa Ag Fa Electro-optical light valve utilizing charged particle migration
US3782932A (en) * 1972-09-20 1974-01-01 Xerox Corp Electrophoretic imaging process using transparent particles
US3954465A (en) * 1972-09-20 1976-05-04 Xerox Corporation Electrophoretic imaging members
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 (3)

* Cited by examiner, † Cited by third party
Title
L'Onde Electrique, Volume 59, No. 10, October 1979 (Paris, FR) J.L. PLOIX et al "Afficheurs par Electrophorese" see pages 65-69, in particular page 66, right-hand column see paragraph III *
Optics Communications, Volume 15, No. 2, October 1975 (Amsterdam, NL) T. YOSHIMURA et al. "The Spectral Profile of Light Scattered by Particles in Electrophoretic Movement", see pages 277-280 *
Proceedings of the SID, Volume 18, No. 3/4, 1977 (Los Angeles, US) I. OTA et al. "Developments in electrophoretic Displays", see pages 243-254, in particular page 244, paragraph B and page 245, paragraph III *

Cited By (31)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6118426A (en) * 1995-07-20 2000-09-12 E Ink Corporation Transducers and indicators having printed displays
US6459418B1 (en) 1995-07-20 2002-10-01 E Ink Corporation Displays combining active and non-active inks
US6639578B1 (en) 1995-07-20 2003-10-28 E Ink Corporation Flexible displays
WO1998041899A2 (en) * 1997-03-18 1998-09-24 Massachusetts Institute Of Technology Improved microencapsulated electrophoretic display
WO1998041899A3 (en) * 1997-03-18 1998-10-29 Massachusetts Inst Technology Improved microencapsulated electrophoretic display
US5961804A (en) * 1997-03-18 1999-10-05 Massachusetts Institute Of Technology Microencapsulated electrophoretic display
WO1999010767A1 (en) * 1997-08-28 1999-03-04 E-Ink Corporation Electrophoretic displays and materials
US6252564B1 (en) 1997-08-28 2001-06-26 E Ink Corporation Tiled displays
US6825829B1 (en) 1997-08-28 2004-11-30 E Ink Corporation Adhesive backed displays
US9268191B2 (en) 1997-08-28 2016-02-23 E Ink Corporation Multi-color electrophoretic displays
US7728811B2 (en) 1997-08-28 2010-06-01 E Ink Corporation Adhesive backed displays
US9293511B2 (en) 1998-07-08 2016-03-22 E Ink Corporation Methods for achieving improved color in microencapsulated electrophoretic devices
US7382514B2 (en) 2002-02-11 2008-06-03 Sipix Imaging, Inc. Core-shell particles for electrophoretic display
WO2003069403A1 (en) * 2002-02-11 2003-08-21 Sipix Imaging, Inc. Core-shell particles for electrophoretic display
US11294255B2 (en) 2002-06-10 2022-04-05 E Ink Corporation Components and methods for use in electro-optic displays
US8854721B2 (en) 2002-06-10 2014-10-07 E Ink Corporation Components and testing methods for use in the production of electro-optic displays
US9778536B2 (en) 2002-06-10 2017-10-03 E Ink Corporation Components and methods for use in electro-optic displays
US9182646B2 (en) 2002-06-10 2015-11-10 E Ink Corporation Electro-optic displays, and processes for the production thereof
US9733540B2 (en) 2002-06-10 2017-08-15 E Ink Corporation Components and methods for use in electro-optic displays
US9470950B2 (en) 2002-06-10 2016-10-18 E Ink Corporation Electro-optic displays, and processes for the production thereof
US9563099B2 (en) 2002-06-10 2017-02-07 E Ink Corporation Components and methods for use in electro-optic displays
US9075280B2 (en) 2002-09-03 2015-07-07 E Ink Corporation Components and methods for use in electro-optic displays
US10444590B2 (en) 2002-09-03 2019-10-15 E Ink Corporation Electro-optic displays
US10599005B2 (en) 2002-09-03 2020-03-24 E Ink Corporation Electro-optic displays
US11520179B2 (en) 2002-09-03 2022-12-06 E Ink Corporation Method of forming an electrophoretic display having a color filter array
US9740076B2 (en) 2003-12-05 2017-08-22 E Ink Corporation Multi-color electrophoretic displays
US9829764B2 (en) 2003-12-05 2017-11-28 E Ink Corporation Multi-color electrophoretic displays
US9005494B2 (en) 2004-01-20 2015-04-14 E Ink Corporation Preparation of capsules
US9726959B2 (en) 2005-10-18 2017-08-08 E Ink Corporation Color electro-optic displays, and processes for the production thereof
US9170467B2 (en) 2005-10-18 2015-10-27 E Ink Corporation Color electro-optic displays, and processes for the production thereof
US11733580B2 (en) 2010-05-21 2023-08-22 E Ink Corporation Method for driving two layer variable transmission display

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Publication number Publication date
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