US006961167B2
`
`(12) United States Patent
`Prins et al.
`
`(10) Patent N0.:
`(45) Date of Patent:
`
`US 6,961,167 B2
`Nov. 1, 2005
`
`(54)
`
`DISPLAY DEVICE BASED ON FRUSTRATED
`TOTAL INTERNAL REFLECTION
`
`(75) Inventors: Menno Willem Jose Prins, Eindhoven
`(NL); Hugo Johan Cornelissen,
`Eindhoven (NL)
`
`(73) Assignee: Koninklijke Philips Electronics N.V.,
`Eindhoven (NL)
`
`( * ) Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 61 days.
`
`(21)
`(22)
`(86)
`
`Appl. No.:
`
`10/479,360
`
`PCT Filed:
`
`Jun. 4, 2002
`
`PCT No.:
`
`PCT/ IB02/ 02041
`
`§ 371 (6X1),
`(2), (4) Date:
`
`Dec. 2, 2003
`
`(87) PCT Pub. No.: WO02/099527
`
`(52) US. Cl. ..................... .. 359/253; 359/228; 359/832
`(58) Field of Search .............................. .. 359/228, 245,
`359/250, 252, 253, 263, 290, 295, 296, 297,
`359/529, 530, 619, 621, 625, 832; 345/48,
`345/55, 84, 85, 107, 349/86, 89; 430/32,
`430/34, 35
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`9/2002 Onuki et al. .............. .. 359/245
`6,449,081 B1 *
`6,819,471 B2 * 11/2004 Amundson et al. ....... .. 359/296
`
`OTHER PUBLICATIONS
`
`Michele A. Mossman et al., “New Re?ective Display Based
`on Total Internal Re?ection In Prismatic Microstructures ”
`Proc. 20th IDRC conference, pp.311-314 (2000).
`
`* cited by examiner
`Primary Examiner—Georgia Epps
`Assistant Examiner—William Choi
`
`PCT Pub. Date: Dec. 12, 2002
`
`(57)
`
`ABSTRACT
`
`(65)
`
`Prior Publication Data
`
`US 2004/0160684 A1
`
`Aug. 19, 2004
`
`Foreign Application Priority Data
`(30)
`Jun. 5, 2001
`
`(EP) ................................ .. 01202127
`
`Pixels of a display device include a reservoir containing tWo
`immiscible ?uids. Switching of a pixel state is based on
`redistribution of the ?uids Within the reservoir due to
`electrostatic forced applied onto electrodes, and a potential
`applied to one of the ?uids Which is electrically conducting.
`
`(51) Int. Cl? ........................ .. G02F1/07; G02B 26/02;
`G02B 5/06
`
`20 Claims, 3 Drawing Sheets
`
`Vccm1=0V
`
`5
`
`/1l//L///////////////‘/'/l’///
`
`§~2
`
`V_
`p1xeI=V—-/
`
`_,
`/,
`
`__
`
`_ ‘2% a
`...... ..
`"
`/;__7'
`
`J? rf/[U///////J//l7/
`
`//Y//
`
`4
`
`V c0m2 =V
`
`6
`
`Patent Owner’s Exhibit 2003
`IPR2015-00022
`Page 1 of 7
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`

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`U.S. Patent
`
`Nov. 1,2005
`
`Sheet 1 013
`
`US 6,961,167 B2
`
`1 /'
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`4
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`6
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`Vcom2 =V
`FIG. 1a
`
`5
`Vccm1=OV
`J
`i
`l/////////j/////7///l
`
`1/ 4
`
`V/ ////////////A//l
`|
`Vcom2 =V
`FIG. 1b
`
`6
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`4
`
`oom2 =V
`
`6
`
`Patent Owner’s Exhibit 2003
`IPR2015-00022
`Page 2 of 7
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`U.S. Patent
`
`Nov. 1,2005
`
`Sheet 2 013
`
`US 6,961,167 B2
`
`FIG. 3a
`
`FIG. 3b
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`Patent Owner’s Exhibit 2003
`IPR2015-00022
`Page 3 of 7
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`

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`US. Patent
`
`Nov. 1, 2005
`
`Sheet 3 013
`
`US 6,961,167 B2
`
`
`
`FIG. 5
`
`Patent Owner‘s Exhibit 2003
`|PR2015-00022
`Page 4 of 7
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`Patent Owner’s Exhibit 2003
`IPR2015-00022
`Page 4 of 7
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`

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`US 6,961,167 B2
`
`1
`DISPLAY DEVICE BASED ON FRUSTRATED
`TOTAL INTERNAL REFLECTION
`
`The invention relates to a display device comprising a
`substantially transparent substrate having a substantially ?at
`surface and a substantially prismatic surface facing said ?at
`surface.
`Adisplay device of this type is described in, for example,
`the article in “NeW Re?ective Display Based on Total
`Internal Re?ection in Prismatic Microstructures” Proc. 20th
`IDRC conference, pp. 311—314 (2000). This article
`describes the principle of total internal re?ection based on
`controlled frustration. The total internal re?ection is made
`impossible in one state by moving light-absorbing particles
`toWards the prismatic surface by means of electrophoresis.
`Electrophoretic display devices are based on the move
`ment of charged, usually colored particles under the in?u
`ence of an electric ?eld betWeen tWo extreme states having
`a different transmissivity or re?ectivity. With these devices,
`dark (colored) characters can be imaged on a light (colored)
`background, and vice versa.
`Electrophoretic display devices are therefore notably used
`in display devices taking over the function of paper, referred
`to as “White paper” applications (electronic neWspapers,
`electronic diaries).
`The present invention is based on a completely different
`mechanism for realiZing the differences in re?ected light in
`the tWo (dark and light) optical states.
`To this end, a display device according to the invention
`comprises a reservoir at the location of a pixel, Which
`reservoir contains at least tWo substantially immiscible
`?uids having a different refractive index or a different
`absorption coefficient, and a difference of electric conduc
`tivity, said display device also comprising drive means for
`displacing the ?uids With respect to each other.
`As Will be explained hereinafter, the light is completely
`re?ected in one of the tWo states, (by suitable choice of one
`of the ?uids and hence the refractive index), While the light
`is absorbed by the ?uid in the other state (or either or not
`partly transmitted and absorbed elseWhere).
`The substrate surface facing the vieWer on the vieWing
`side may be ?at, With at least a part of the prismatic surface
`of the substrate forming part of a Wall of the reservoir.
`Alternatively, it may be prismatic, With at least a part of the
`?at surface of the substrate forming part of a Wall of the
`reservoir.
`In order to displace the ?uids With respect to each other,
`use is made of the difference of electric conductance and, at
`the area of the Wall of the reservoir of a pixel, the drive
`means comprise at least tWo electrodes Which can be elec
`trically coupled to the ?uids.
`At the area of the Wall of the reservoir of a pixel, the drive
`means preferably comprise tWo electrodes Which are iso
`lated from the ?uids, and a third electrode Which is in
`electric contact With the electrically conducting ?uid.
`To this end, a matrix device comprises a plurality of pixels
`at the area of crossings of roW or selection electrodes and
`column or data electrodes, With at least a sWitching element
`betWeen an electrode of the pixel and a roW or column
`electrode.
`These and other aspects of the invention are apparent
`from and Will be elucidated With reference to the embodi
`ments described hereinafter.
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`In the draWings:
`FIG. 1 shoWs diagrammatically the principle on Which a
`display device according to the invention is based,
`FIG. 2 shoWs a variant of FIG. 1,
`FIG. 3 shoWs a possible form of a display cell according
`to the invention, While
`FIG. 4 shoWs another possible form of a display cell
`according to the invention, and
`FIG. 5 is an electric equivalent diagram of a display
`device according to the invention.
`The Figures are diagrammatic and not draWn to scale;
`corresponding components are generally denoted by the
`same reference numerals.
`FIG. 1 shoWs diagrammatically a display cell 1 With tWo
`liquids, or ?uids, 3, 4 in a transparent, for example, glass or
`synthetic material envelope 2, Which ?uids do not mix With
`each other and one of Which is electrically conducting and
`the other is insulating. In this example, the display cell 1
`comprises, for example an aqueous (color) solution 4 (elec
`trically conducting), for example, a solution in Water of
`methylene blue or Prussian blue (C6Fe2Kn6), While a gas
`such as nitrogen or a non-polar oil such as an alcane (for
`example, dodecane or hexadecane), a silicon oil, chlo
`ronaphtalene, bromonaphtalene, or l-bromododecane is
`chosen as an insulating ?uid.
`On tWo sides of the ?uids, the display cell 1 comprises
`insulated electrodes 5, 6 Which are usually fed With voltages
`Vcoml, Vwm2 Which are common for a plurality of pixels, in
`the relevant example With voltages of 0 and V. The display
`cell 1 also comprises an electrode 7 Which makes electrically
`conducting contact through the envelope 2 With the electri
`cally conducting ?uid 4. The electrode 7 is fed With a voltage
`Vpixel by means of Which the optical state of the display cell
`is adjusted. Although, for the sake of understanding the
`invention, the electrodes 5, 6 are shoWn outside the enve
`lope, they are provided Within the envelope 2 in practice and
`insulated from the ?uids by means of an insulating coating
`having a loW Wetting hysteresis such as a ?uoropolymer.
`The electrically conducting ?uid 4 is attracted by elec
`trostatic forces in the direction of the electrodes 5, 6, namely
`toWards the electrode 5 With a force Which is proportional to
`(Vpixel—VC0m1)2 and toWards the electrode 6 With a force
`Which is proportional to (VpixerVcomz)2 due to electroWet
`ting or electrocapillarity. The difference betWeen the respec
`tive electrostatic forces de?nes the position of the ?uid 4 in
`a display cell. In FIG. 1, Vcoml=0 and Vwm2=V. When
`Vpixel=0, the electrically conducting ?uid 4 is at the location
`of electrode 6 (FIG. 1a), While the electrically conducting
`?uid 4 is at the location of electrode 5 (FIG. 1b) When
`VpixeFV. By changing the pixel potential Vpixel, the location
`of the electrically conducting ?uid 4 can thus be in?uenced.
`Although the electrode 7 is shoWn as a conducting electrode
`in this example, and, moreover, projects into the ?uid, this
`is not necessary. The potential may also be provided on the
`conducting ?uid via capacitive coupling. In that case, the
`electrode 7 is arranged, for example, outside the reservoir 2
`or provided With an insulating protective coating.
`FIG. 2 shoWs a variant of FIG. 1, in Which the electrode
`7, Which is again fed With a voltage Vpixe, is subdivided into
`tWo sub-electrodes 7, 7‘. The interface betWeen the ?uids is
`noW substantially parallel to the upper and loWer Wall of the
`envelope 2, With a small deviation in the plane of the
`draWing, due to the effect used (in FIG. 2, this is shoWn
`diagrammatically by means of the slanting line 8).
`FIG. 3 shoWs hoW the principle described above is used
`in a display device based on total internal re?ection. A
`display cell 1 comprises a transparent substrate 10 of glass
`
`Patent Owner’s Exhibit 2003
`IPR2015-00022
`Page 5 of 7
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`US 6,961,167 B2
`
`3
`or a synthetic material, having a substantially ?at surface 11
`and a substantially prismatic surface 12, 12‘ opposite said
`?at surface. The display cell comprises a reservoir 13 Which
`contains at least tWo immiscible ?uids 3, 4 having a different
`refractive index, Which ?uids do not mix With each other and
`one of Which is an electrically conducting ?uid and the other
`is an insulating ?uid. The display cell 1 also comprises an
`electrode 7 Which is fed With a voltage Vpixe, and makes
`electrically conducting contact through the envelope (not
`shoWn) With the electrically conducting ?uid 4. Although
`this is not shoWn in FIG. 3, it is favorable if the display cells
`have a common over?oW reservoir for the tWo ?uids (either
`or not for a plurality of display cells) in connection With
`expansion upon temperature changes etc. The display cell
`comprises insulated electrodes 5, 6 on tWo sides of the ?uids,
`Which electrodes are fed With common voltages V
`Vcomz, in the relevant example With voltages 0 and V.
`When Vpixel=0, the electrically conducting ?uid 4 is at the
`location of electrode 6 (FIG. 3a), While the electrically
`conducting ?uid 4 is at the location of electrode 5 (FIG. 3b,
`in Which the electrodes are not shoWn) When Vpixel=V. An
`incident light ray 14 is transmitted in the ?rst mentioned case
`(FIG. 3a) by the transparent (ITO) electrode 5 and undergoes
`total re?ection on the surface 12 by suitably choice of the
`refractive index of the insulating ?uid. The re?ected light
`ray 14‘ once more undergoes total re?ection on the surface
`12‘ and the tWice re?ected light ray 14“ leaves the display
`cell 1 substantially Without any loss of light. In the second
`case (FIG. 3b), the incident light ray 14 is also transmitted
`by the transparent (ITO) electrode 5, but is subsequently
`absorbed entirely or partly on the surface 12 by the aqueous
`solution 4. Apossibly re?ected part 14‘ of the light ray 14 is
`absorbed on the surface 12‘.
`In this example, the electrode 6 is only shoWn on the
`loWer side of the pixel because this is favorable When
`combining several pixels on one substrate, for example, in a
`matrix display device. In other cases, it is advantageous to
`provide the electrode 6 also along the Wall of the reservoir
`13. This is shoWn diagrammatically by means of broken
`lines in FIG. 3a.
`FIG. 4 shoWs diagrammatically a combination of tWo
`similar pixels With reservoirs as described With reference to
`FIG. 2, but noW With a substantially ?at surface 11 on the
`side of the pixel and a substantially prismatic surface 12, 12‘
`on the vieWing side. OtherWise, the reference numerals have
`the same signi?cance as in the previous Figures.
`FIG. 5 shoWs an electrical equivalent of a part of a color
`display device 1 to Which the invention is applicable. It
`comprises a matrix of pixels 20 at the area of crossings of
`roW or selection electrodes 27 and column or data electrodes
`26. The roW electrodes 1 to m are consecutively selected by
`means of a roW driver 24, While the column electrodes 1 to
`n are provided With data via a data register 25. The pixels in
`columns 1, 4, 7, .
`.
`.
`, n—2 constitute red pixels in this
`example, the pixels in columns 2, 5, 8, .
`.
`.
`, n—1 constitute
`blue pixels in this example, and the pixels in columns 3, 6,
`9, .
`.
`. , n constitute green pixels. To this end, incoming data
`22 are ?rst processed, if necessary, in a processor 23. Mutual
`synchroniZation betWeen the roW driver 24 and the data
`register 25 takes place via drive lines 28.
`Drive signals from the roW driver 24 and the data register
`25 select a pixel 20 via thin-?lm transistors (TFTs) 29 Whose
`gate electrodes are electrically connected to the roW elec
`trodes 27 and Whose source electrodes are electrically con
`nected to the column electrodes 26 (referred to as active
`drive). The signal at the column electrode 26 is transferred
`via the TFT to an electrode 7 of a pixel 20 coupled to the
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`drain electrode. The electrode 7 has the same function as
`described above With reference to FIGS. 1 to 4. The other
`electrodes 5, 6 of the pixel 20 are connected, for example,
`to one (or more) common electrode or electrodes With Vcom1
`(in this example, ground) and Vwm2 (in this example, V). In
`the example of FIG. 5, such a TFT 29 is shoWn diagram
`matically for only one pixel 20.
`Several variations are of course possible Within the scope
`of the invention. For example, use may be made of tWo
`immiscible ?uids having a different refractive index. In
`certain electrode con?gurations, it is possible that the inci
`dent beam reaches the loWer side of the pixel. If desired, the
`pixel may be provided With a light-absorbing layer on the
`loWer side.
`Instead of the thin-?lm transistors (TFTs) 29, other
`sWitching elements may be chosen, for example, a diode
`circuit.
`The third electrode 5 may also be omitted, provided that
`the ?uids 3, 4 used have such a difference of hydrophobic
`properties that the described displacement occurs (the Walls
`have a difference of Wetting behavior). One of the tWo
`electrodes then functions as a drive electrode.
`As stated, use may also be made of capacitive coupling;
`this also applies to driving of the electrodes by means of the
`TFTs or other sWitching elements.
`The protective scope of the invention is not limited to the
`embodiments described.
`The invention resides in each and every novel character
`istic feature and each and every combination of character
`istic features. Reference numerals in the claims do not limit
`their protective scope. Use of the verb “comprise” and its
`conjugations does not exclude the presence of elements
`other than those stated in the claims. Use of the article “a”
`or “an” preceding an element does not exclude the presence
`of a plurality of such elements.
`
`What is claimed is:
`1. A display device comprising a substantially transparent
`substrate having a substantially ?at surface and a substan
`tially prismatic surface facing said ?at surface, said display
`device comprising a reservoir at the location of a pixel,
`Which reservoir contains at least tWo substantially immis
`cible ?uids having a different refractive index or a different
`absorption coefficient, and a difference of electric conduc
`tivity, said display device also comprising drive means for
`displacing the ?uids With respect to each other.
`2. Adisplay device as claimed in claim 1, comprising tWo
`immiscible ?uids having a different refractive index, one of
`Which is electrically conducting and one is substantially
`insulating.
`3. A display device as claimed in claim 1, With the ?at
`surface of the substrate on the vieWing side, Wherein at least
`a part of the prismatic surface of the substrate forms part of
`a Wall of the reservoir.
`4. A display device as claimed in claim 1, With the
`prismatic surface of the substrate on the vieWing side,
`Wherein at least a part of the ?at surface of the substrate
`forms part of a Wall of the reservoir.
`5. A display device as claimed in claim 1, Wherein the
`drive means at the area of the Wall of the reservoir of a pixel
`comprise at least tWo electrodes Which can be electrically
`coupled to the ?uids.
`6. A display device as claimed in claim 5, Wherein the
`drive means at the area of the Wall of the reservoir of a pixel
`comprise tWo electrodes Which are isolated from the ?uids,
`and a third electrode Which is in electric contact With the
`electrically conducting ?uid.
`
`Patent Owner’s Exhibit 2003
`IPR2015-00022
`Page 6 of 7
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`US 6,961,167 B2
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`5
`7. A display device as claimed in claim 1, comprising a
`plurality of pixels at the area of crossings of row or selection
`electrodes and column or data electrodes, with at least a
`switching element between an electrode of the pixel and a
`row or column electrode.
`8. A display device as claimed in claim 7, with a TFT
`transistor per pixel between the electrode and a column
`electrode, wherein the gate of the TFT transistor is con
`nected to a row electrode.
`9. The display device of claim 1, wherein a ?rst one of the
`two immiscible ?uids has a refractive index substantially
`different from a refractive index of the substrate, and
`wherein the display device is operative in a ?rst state to
`re?ect light when the ?rst ?uid is displaced within the
`reservoir to be adjacent to the substantially transparent
`substrate, and wherein the display device is operative in a
`second state to absorb light when the second ?uid is dis
`placed within the reservoir to be adjacent to the substantially
`transparent substrate.
`10. The display device of claim 9, wherein the device is
`operable to receive the light at the substantially ?at surface
`of the substrate, and wherein the light is re?ected at the
`substantially prismatic surface of the substrate to exit the
`substrate at the substantially ?at surface.
`11. The display device of claim 9, wherein the device is
`operable to receive the light at the substantially prismatic
`surface of the substrate, and wherein the light is re?ected at
`the substantially ?at surface of the substrate to exit the
`substrate at the substantially prismatic surface.
`12. The display device of claim 9, wherein the ?rst liquid
`is an insulating ?uid.
`13. The display device of claim 1, wherein the drive
`means includes two electrodes physically insulated from the
`two substantially immiscible ?uids.
`14. A display device comprising:
`a substantially transparent substrate having a substantially
`?at ?rst surface and a substantially prismatic second
`surface opposite said ?rst surface;
`a plurality of row electrodes extending in parallel across
`the substrate in a ?rst direction;
`a plurality of column electrodes extending in parallel
`across the substrate in a second direction; and
`a plurality of pixels arranged in a matrix at areas where
`the row electrodes cross the column electrodes,
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`wherein each pixel comprises:
`a reservoir containing two substantially immiscible
`?uids having a different refractive index or a differ
`ent absorption coefficient with respect to each other,
`and a difference of electric conductivity with respect
`to each other, and
`means for selectively displacing the two ?uids with
`respect to each other, wherein in a ?rst arrangement
`of the ?uids light received by the pixel is substan
`tially re?ected by the pixel, and in a second arrange
`ment of the ?uids light received by the pixel is
`substantially absorbed by the pixel.
`15. The device of claim 14, wherein the means for
`selectively displacing the two ?uids with respect to each
`other includes two electrodes adapted to provide a voltage
`potential across at least one of the ?uids.
`16. The device of claim 14, wherein the means for
`selectively displacing the two ?uids with respect to each
`other includes two electrodes which are isolated from the
`?uids, and a third electrode which is in electric contact with
`the electrically conducting ?uid.
`17. The device of claim 16, wherein each pixel further
`comprises a transistor having a gate connected to a corre
`sponding one of the row electrodes, having a ?rst terminal
`connected to a corresponding one of the column electrodes,
`and having a second terminal connected to the third elec
`trode of the means for selectively displacing the two ?uids
`with respect to each other.
`18. The device of claim 14, wherein at least a part of the
`prismatic surface of the substrate forms part of a wall of the
`reservoir.
`19. The device of claim 14, wherein at least a part of the
`?at surface of the substrate forms part of a wall of the
`reservoir.
`20. The device of claim 14, wherein a ?rst one of the two
`immiscible ?uids has a refractive index substantially differ
`ent from a refractive index of the substrate, and wherein in
`the ?rst arrangement the ?rst ?uid is displaced within the
`reservoir to be adjacent to the substantially transparent
`substrate, and wherein in the second arrangement the second
`?uid is displaced within the reservoir to be adjacent to the
`substantially transparent substrate.
`
`Patent Owner’s Exhibit 2003
`IPR2015-00022
`Page 7 of 7
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