CA1056524A - Displays using liquid mediums - Google Patents
Displays using liquid mediumsInfo
- Publication number
- CA1056524A CA1056524A CA267,320A CA267320A CA1056524A CA 1056524 A CA1056524 A CA 1056524A CA 267320 A CA267320 A CA 267320A CA 1056524 A CA1056524 A CA 1056524A
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- Canada
- Prior art keywords
- polymer
- polymers
- group
- vinyl
- polyvinylcarbazole
- 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.)
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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
- G02F1/061—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 electro-optical organic material
-
- 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
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- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Molecular Biology (AREA)
- Liquid Crystal (AREA)
- Electrochromic Elements, Electrophoresis, Or Variable Reflection Or Absorption Elements (AREA)
- Devices For Indicating Variable Information By Combining Individual Elements (AREA)
- Photoreceptors In Electrophotography (AREA)
- Duplication Or Marking (AREA)
Abstract
DISPLAYS USING LIQUID MEDIUMS
Abstract of the Disclosure An apparatus and a process for displaying a visible image are disclosed. A solution in liquid of at least two types of polymeric materials contained between two electrodes, at least one of which is transparent, is subjected to imagewise elec-trical voltage. The polymers comprise cellulose nitrate, polyester, polyvinylcarbazole, and formaldehyde condensation polymers.
Abstract of the Disclosure An apparatus and a process for displaying a visible image are disclosed. A solution in liquid of at least two types of polymeric materials contained between two electrodes, at least one of which is transparent, is subjected to imagewise elec-trical voltage. The polymers comprise cellulose nitrate, polyester, polyvinylcarbazole, and formaldehyde condensation polymers.
Description
~o Field o f the Invention 11 The present invention is concerned with an apparatus for 12 displaying a visible image and with a process for so doing.
13 In particular, it is concerned with the use in such an appara-14 tus and process of mixtures containing cellulose nitrate, ~,5 polyester, polyvinylcarbazole, and formaldehyde condensation 16 polymers.
17 Prior ~rt 18 There are many various types of apparatus and processes g for ~isplaying images. Many such prior art devices involve the ~se of liquid crystals. The present lnvention, however, 21 is clearly distinguishable from any li~uid crystal work in 22 that the present invention involves solutions in a liauid medium. In the case of liquid crystals, there is no liquid ~ medium involved. Still an additional difference between the 2S present process and one involving liquid crystals is that in 26 the case of liquid crystals, information is displayed by ?.7 using changes in the anisotropic properties o liquid crystals ~3 while in the present invention it is believed that the 29 operation does not depend upon chang,es in isotropy.
.
.3~
,, 1 ,..
~, .
~S6SZ4 1 The art also teaches the phenomenon of electrical bire
13 In particular, it is concerned with the use in such an appara-14 tus and process of mixtures containing cellulose nitrate, ~,5 polyester, polyvinylcarbazole, and formaldehyde condensation 16 polymers.
17 Prior ~rt 18 There are many various types of apparatus and processes g for ~isplaying images. Many such prior art devices involve the ~se of liquid crystals. The present lnvention, however, 21 is clearly distinguishable from any li~uid crystal work in 22 that the present invention involves solutions in a liauid medium. In the case of liquid crystals, there is no liquid ~ medium involved. Still an additional difference between the 2S present process and one involving liquid crystals is that in 26 the case of liquid crystals, information is displayed by ?.7 using changes in the anisotropic properties o liquid crystals ~3 while in the present invention it is believed that the 29 operation does not depend upon chang,es in isotropy.
.
.3~
,, 1 ,..
~, .
~S6SZ4 1 The art also teaches the phenomenon of electrical bire
2 fringence. In t~e phenomenon of electrical birefringence polymer
3 molecules, under the in~luence of an electrical field, are
4 formed into microcrystallites or micellar suspensions which scatter light. The present invention, however, is clearly 6 distinguished from the phenomenon of ~lectrical birefringence 7 since, although it cannot be said with c~rtainty what the 8 mechanism o~ the p~esent invention is, ~t appears to depend 9 o~ the use of two different polymers simultaneously and it does not appear that, like eLectrical birefringence, it 11 depends upon the in~luence of an electrical field alone.
12 Summary of the Invention .
13 The present invention provides an apparatus and a process 14 for displaying a visible image. The apparatus comprises two substantially parallel planar electrodes, at least one of which 16 is transparent. Contained between these electrodes is a 17 solution in liquid of a polymeric composition. This polymeric 18 composition should contain at least two polymers at least one 19 of which is selected from the group consisting of cellulose nitrate, polyester, polyvinylcarbazole, and formaldehyde son-21 densation polymers.
22 The solution of polymers in liquid is, in the process of 23 the present invention, subjected to the application of 24 electrical voltage in an imagewise manner. There are at least two ways in which a voltage may be a~plied in an imagewise 26 manner. In one way, the polymeric material is photoconductive t 27 and it is subjected to an imagewise exposure to light. Only 28 at those portions where exposur~ ~o light has taken place does '.`;5~ -2-~ ., .
~05~;52~
1 a change in appearanc~ of the polym~ric composition take 2 place.
3 It is,~, however, not essential for the purposes of the 4 present invention ~hat the polymeric composition be photocon-S ductive. Non-photoconductiv2 polymers can also be used. When 6 such a non-photoconductive polymer system is used t the imagewise 7 app}ication of voltage can be accomplished by means of matrix 8 addressing. The use of such a matrix addressin~ device is g well known in the art.
Cellulose nitrate, polyester, polyvinylcarbazole, and 11` ~ormaldehyde condensation polymers are useful in the present 12 invention. The term polymer is used here to include copoly-13 . mers and terpolymers. In particular, cellulose nitrate may 14 be mixed with other polymers, including both photoconduc~ive lS and non-photoconductive polymers, such as:
16 ta) polymethylene-N-ethyl carba~ole polymer~-17 , (b) 3-vinyl-10-methyl phenothiazine polymer;
18 tc) styrene copolymerized with 2-vinyl pyridine;
-19 Sd) dibenzothiophene condensation polymer with formalde-2Q hyde;
21 ~e) l-vinyl naphthalene polymer;
~2 . (f) formaldehyde condensation polymer with dibenzo-23 thiophene and dibenzo~uran;
24 (g) polyvinylcarbazole;
(h) polyester such as Vitel* PEZ22;
26 (i~ polystyrene.
27 In like manner, formaldehyde condensation polymers, 28 polyvinylcarbazole and polyesters may also be mixed with each ~g other and with other polymers.
*Registered Trade Mark ~ S65~
1 The choice of optimum liquid solvent will depend upon 2 the particular polymers being used. Typical useful liquids 3 include, for example, tetrahydrofuran (THF), methyl ethyl 4 ketone ~MEK), acetone, dimethylformamide (DMF), and mixtures of these~
6 ` Glass is a pre~erred material for use as an electrode, 7 provided it has been rendered conductive to electricity, for 8 example, by coating it with a conductor. NESA glass, which is g glass coated with tin oxide, is particularly preferred, since it is very conductive and ~lso very transparent. Two sheets 11 of NESA glass are a preferred example o~ two planar, substan-12 tially parallel electrodes. Other materials useful to coat 13 glass electrodes include indium oxide, and thin metallic 14 l~yers of platinum, gold or aluminum.
As mentioned above, the operation of the present inven-16 tion, unlike the phenomenon of electrical birefringence, is 17 not believed to depend upon an electrical field effect. This 18 has been proved by a simple experiment in which a thin dielec-19 tric has been placed between the electrodes. If the process is dependent upon field effect, it should operate even in the 21 presence of the dielectric. The present process does not 22 operate under such conditions, however.
23 It is believed that the change in appearance of the sus-24 pended polymers occurs when, and only when, the applied voltage exceeds a certain minimum threshold. This threshold 26 appears to vary from about 2 volts in some cases up to about 27 15 volts in other cases. The usual range is from about 4 to 28 about 8 volts. It is believed that in those instances where 2~ photoconductive polymers are used in conjunction with exposure to light, the resistivity of the suspension is lowered in :J~056S24 1 ~hose areas exposed to light, and the threshold is exceeded 2 only in those areas. In a similar manner, when a matrix 3 addressing is used, the potentials of the individual electrodes 4 are chosen so that the threshold is exceeded only at selected places where the electrodes cross over each other, The 6 existence of a thre~hold insures that only the desired cross-7 points will be activated.
B Without wishing to impose any limitation on the scope of g the invention, the following is proposed as a possible mechanism for the present invention. In every case where 11 voltage induced scattering is observed, the unexcited polymer 12 solution has an opalescent appearance of varying degrees.
13 Voltage induced scattering in completely transparent clear 14 solutions has not been observed. Each polymer in the combina-tion of polymers may be soluble in the solvent. When the 16 polymers are added together, however, they form a slightly 17 immiscible emulsion giving the "solution" an opalescent 18 appearance.
19 When the "solution'l is added to the cell, the respective polymers may assume a configuration as follows:
21 _ B
27 where A and B are different polymers in the same solvent.
28 There may be some intermixing of the two polymers A and B, 29 giving the solution a frosty appearance.
~0~;5~4 . ~ _ .
A A
2 o B ~
3 B e o-~ B
4 . _ S
~ When a voltage is applied, the polymers A and B migrate to 7 separate electrodes g ~) .
11 A _ 12 ¦ A B .. A
13 ~ ) ~ A ~`~ t 14 ¦ B B B B
L
16 (-) 18 The first observed effect is that of scat-tering or 19 increased opacity as the polymers A and B intermix. However, 20 with continued application of voltagè a sheet of A and a 21 sheet of B is formed on their respective electrodes.
A A
27 and the result is a clear or transparent cell since intermixing 28 is minimal.
29 In order to maximize scattering or intermixing, the polarity would have to be constantly switched. This explana-31 tion is consistent with the results obtained under various :1 OS~;S24 1 conditions, i.e. at first the cell produces scattering when 2 voltage is applied. As the voltage is left on -the cell 3 eventually clears and remains mostly clear as long as the 4 voltage is on. When the potential is reversed, the cell again becomes scattering and then clears.
6 In the case of the formaldehyde condensation pQlymers, 7 it is believe~ that the polymers contain different molecular 8 weight fractions, which have different solubility characteristics, g so that in effect two phases are obtained. This also is con-sistent with the observation that the formaldehyde condensa-11 tion polymers form 2 liquid layers on standing, with one of 12 the layers having an oil like appearance.
13 The following examples are given solely for purposes of 14 illustration and are not to be considered limitations on the invention, many variations of which are possible without 16 departing from the spirit or scope thereof.
18 A composition containing one part 3-vinyl-10-methyl 19 phenothiazine polymer and one part cellulose nitrate resin was added to 20 parts tetrahydrofuran solvent. A viscous 21 opalescent appearing solution was obtained. The solution was ~2 placed in a thin cell consisting of two glass plates each 23 coated with a thin transparent elect~ically conductive layer 24 of tin oxide. The glass plates, which were separated by a 75 micron mylar spacer, were arranged in a parallel plate electrode 26 configuration and were connected to a power supply. The 27 solution in the thin cell had a very slightly hazy appearance 28 prior to application of voltage across the cell. When a 29 potential of about 10 volts was applied, a highly scattering ~05/E;S2~
1 opa~ue layer was obtained. The layer was made clear or trans-2 parent by applying a~short pulse of voltage opposite in 3 polarity t~ that used to produce the scattering.
4 The addition of a small amount (~10~ by weiyht of total solids) of carbon tetrabromide was used to make the layer 6 beam addressable. That is, the layer contain~d in the cell 7 cou~d be imaged with light so ~hat the portions of the cell a receiving light were clear or transparent and the areas not g receiving light were opaque or scattering.
10 - EX~lPLE ~I -11 A solution containing 30 percent dibenzothiophene formal-12 dehyde condensation polymer in methyl ethyl ke~one was placed 13 in a matrix cell consisting o~ a glass plate with 7 horizontal 14 transparent electrically conductive strips of indium oxide, a 25 micron Myia~ spacer and another glass plate with 5 vertical 16 conductive strips of indium oxide. (Mylar is duPont's brand 17 of polyethylene terephthalate.) This formed a 5 x 7 matrix 18 which was driven by scanning through the 7 lines one at a time 19 . with an applied voltage. The 5 vertical lines had either a select voltage or non-select voltage with reference to the 21 scan line voltaye.
2~ For exampl~, the voltage on the scanned line miyht be ~3 2V and the selected line at -V giving 2V-(-V) or 3V at that 24 cross point twhere V is a threshold voltage below wllich no chan-ge is observed). This 3:1 matrix scheme was used to drive 26 the cell. At a 3V of 10 volts a 25 micron cell showed charac-27 ters with fairly good scatteri~g density in the character area.
28 A 75 micron cell driven at a 3V of 12 volts showed characters 29 with good contrast (opaque in the cross point areas clear in the backyround areas).
*Registered Trade Mark ~C~5~52~
2 Dibenzothiophene formaldehyde condensation polymer (30 parts) 3 was added to methy' ethyl ketone (70 parts) and was placed 4 between conductive tin oxide coated glass plates separated by a 37 micron Mylar spacer. A potential of 2 volts was applied 6 across the cell. No scattering or change in appearance was ob-7 served. The voltage was increased to 4 volts. Again no scatter-8 ing was observed. When 6 volts were applie~ the cell was driven 9 to an opaque light scattering ~tate. This demonstrates a threshold effect or point below which no change is observed.
11 EXAMPI,E IV
1~ A solution containing 30~ by weight of dibenzothiophene 13 formaldehyde condensation polymer in methyl ethyl ketone was 14 placed between transparent conductive tin oxide coated glass plates. The glass plates were separated by a 37 micron Mylar 16 spacer. A 25 volt potential was placed across the cell and the 17 cell was simultaneously exposed to a pattern of ultraviolet 18 light. The areas of the cell receiving the ultraviolet light 19 became opaque or l~ght scattering while the background areas were clear. The image was erased by reversing the polarity of 21 the applied voltage.
23 A cell was constructed of a pair of electrically conduc-~4 tive tin oxide coated glass plates arranged parallel. The plates were separated by a 12 micron Mylar spacer. A composi-26 tion of 5 parts dibenzothiophene-dibenzofuran formaLdehyde 27 terpolymer, 5 parts methyi ethyl ketone and 2 parts acetone 28 was added to the space between the conductive electrodes.
29 A potential of 2 volts applied across the cell was insuffi-cient to produce scattering. Very slight scattering was _g_ ~0565~
1 observed at 4 volts while very good scatkering was obs~rved 2 with 6 volts.
4 A terpolymer of dibenzothiophene dibenzofuran formalde-hyde was added to dimethylformamide at a ratio of 3 parts 6 polymer to 7 parts solvent. The solution was added to a cell 7 constructed as in Example V. A potential up to 4 volts 8 was insufficient to pxoduce scattering. Slight scattering g was observed with 6 volts, and good scattering with 8 volts applied across the cell.
12 A solution of 2 parts oellulose nitrate, 5 parts styrene-13 2-vinyl pyridine copolymer, 14 parts tetrahydrofuran and 14 14 parts methyl ethyl ketone was placed in a cell constructed as described in Example III. The solution was driven to a 1~ scattering state with the application of 20V. The solution 17 was cleared by applying voltage opposite in polarity.
19 A solution of 2 parts cellulose nitrate, 5 parts l-vinyl naphthalene and 28 parts methyl ethyl ketone was added to a 21 cell as in Example VII. Weak scattering was produced when a 22 potential of 20 volts was used to drive the cell.
.
2~ One part cellulose nitrate, 6 parts dibenzothiophene dibenzofura~ formaldehyde terpolymer and 28 parts methyl ethyl 26 ketone were added to a cell as in Example III. The cell was 27 driven to a s~attering state by application of 20 volts.
29 Two parts polyvinylcarbaæole, 1 part cellulose nitrate and 27 parts tetrahydrofuran were added to a cell as in ~)56S; :4 1 Example III. The cell was driven to a scattering state by 2 application of 15 volts.
3 EXAMP~E XI
4 A solution consisting of 1 part Vitel PE222 ~a linear saturated polyester polymer from the Goodyear Tire and Rubber 6 Co.) and 2 parts polyvinylcarbazole in tetrahydrofuran 7 (12% solids by wei~ht) were added to a cell. The cell consisted 8 of parallel conductive coated glass plates separated by a g 19 micron Mylar spacer. The cell was driven to a scatteriny state by the application o~ 30 volts. The cell was cleared 11 by reversing the polarity of applied voltage.
13 A composition containing 3 parts polyvinyl carbazole, 1~ 1 part cellulose nitrate, .03 parts 1',3',3'-trimethyl~6-nitrospiro [2H-l-benzopyran-2,2'-indoline, and 40 parts tetra-16 hydrofuran was added to a cell of transparent tin oxide coated 17 glass plates separated by a 19 micron Mylar spacer. A 15 volt 18 potential was applied across the cell while the cell was exposed 19 to a pattern of light. The background areas were transparent 2~ or clear, while the exposed areas had a frosty or scattering 21 appearance. The image was erased by reversing the polarity 22 and the process was repeated again producing an image in the 23 form of clear and scattering areas.
12 Summary of the Invention .
13 The present invention provides an apparatus and a process 14 for displaying a visible image. The apparatus comprises two substantially parallel planar electrodes, at least one of which 16 is transparent. Contained between these electrodes is a 17 solution in liquid of a polymeric composition. This polymeric 18 composition should contain at least two polymers at least one 19 of which is selected from the group consisting of cellulose nitrate, polyester, polyvinylcarbazole, and formaldehyde son-21 densation polymers.
22 The solution of polymers in liquid is, in the process of 23 the present invention, subjected to the application of 24 electrical voltage in an imagewise manner. There are at least two ways in which a voltage may be a~plied in an imagewise 26 manner. In one way, the polymeric material is photoconductive t 27 and it is subjected to an imagewise exposure to light. Only 28 at those portions where exposur~ ~o light has taken place does '.`;5~ -2-~ ., .
~05~;52~
1 a change in appearanc~ of the polym~ric composition take 2 place.
3 It is,~, however, not essential for the purposes of the 4 present invention ~hat the polymeric composition be photocon-S ductive. Non-photoconductiv2 polymers can also be used. When 6 such a non-photoconductive polymer system is used t the imagewise 7 app}ication of voltage can be accomplished by means of matrix 8 addressing. The use of such a matrix addressin~ device is g well known in the art.
Cellulose nitrate, polyester, polyvinylcarbazole, and 11` ~ormaldehyde condensation polymers are useful in the present 12 invention. The term polymer is used here to include copoly-13 . mers and terpolymers. In particular, cellulose nitrate may 14 be mixed with other polymers, including both photoconduc~ive lS and non-photoconductive polymers, such as:
16 ta) polymethylene-N-ethyl carba~ole polymer~-17 , (b) 3-vinyl-10-methyl phenothiazine polymer;
18 tc) styrene copolymerized with 2-vinyl pyridine;
-19 Sd) dibenzothiophene condensation polymer with formalde-2Q hyde;
21 ~e) l-vinyl naphthalene polymer;
~2 . (f) formaldehyde condensation polymer with dibenzo-23 thiophene and dibenzo~uran;
24 (g) polyvinylcarbazole;
(h) polyester such as Vitel* PEZ22;
26 (i~ polystyrene.
27 In like manner, formaldehyde condensation polymers, 28 polyvinylcarbazole and polyesters may also be mixed with each ~g other and with other polymers.
*Registered Trade Mark ~ S65~
1 The choice of optimum liquid solvent will depend upon 2 the particular polymers being used. Typical useful liquids 3 include, for example, tetrahydrofuran (THF), methyl ethyl 4 ketone ~MEK), acetone, dimethylformamide (DMF), and mixtures of these~
6 ` Glass is a pre~erred material for use as an electrode, 7 provided it has been rendered conductive to electricity, for 8 example, by coating it with a conductor. NESA glass, which is g glass coated with tin oxide, is particularly preferred, since it is very conductive and ~lso very transparent. Two sheets 11 of NESA glass are a preferred example o~ two planar, substan-12 tially parallel electrodes. Other materials useful to coat 13 glass electrodes include indium oxide, and thin metallic 14 l~yers of platinum, gold or aluminum.
As mentioned above, the operation of the present inven-16 tion, unlike the phenomenon of electrical birefringence, is 17 not believed to depend upon an electrical field effect. This 18 has been proved by a simple experiment in which a thin dielec-19 tric has been placed between the electrodes. If the process is dependent upon field effect, it should operate even in the 21 presence of the dielectric. The present process does not 22 operate under such conditions, however.
23 It is believed that the change in appearance of the sus-24 pended polymers occurs when, and only when, the applied voltage exceeds a certain minimum threshold. This threshold 26 appears to vary from about 2 volts in some cases up to about 27 15 volts in other cases. The usual range is from about 4 to 28 about 8 volts. It is believed that in those instances where 2~ photoconductive polymers are used in conjunction with exposure to light, the resistivity of the suspension is lowered in :J~056S24 1 ~hose areas exposed to light, and the threshold is exceeded 2 only in those areas. In a similar manner, when a matrix 3 addressing is used, the potentials of the individual electrodes 4 are chosen so that the threshold is exceeded only at selected places where the electrodes cross over each other, The 6 existence of a thre~hold insures that only the desired cross-7 points will be activated.
B Without wishing to impose any limitation on the scope of g the invention, the following is proposed as a possible mechanism for the present invention. In every case where 11 voltage induced scattering is observed, the unexcited polymer 12 solution has an opalescent appearance of varying degrees.
13 Voltage induced scattering in completely transparent clear 14 solutions has not been observed. Each polymer in the combina-tion of polymers may be soluble in the solvent. When the 16 polymers are added together, however, they form a slightly 17 immiscible emulsion giving the "solution" an opalescent 18 appearance.
19 When the "solution'l is added to the cell, the respective polymers may assume a configuration as follows:
21 _ B
27 where A and B are different polymers in the same solvent.
28 There may be some intermixing of the two polymers A and B, 29 giving the solution a frosty appearance.
~0~;5~4 . ~ _ .
A A
2 o B ~
3 B e o-~ B
4 . _ S
~ When a voltage is applied, the polymers A and B migrate to 7 separate electrodes g ~) .
11 A _ 12 ¦ A B .. A
13 ~ ) ~ A ~`~ t 14 ¦ B B B B
L
16 (-) 18 The first observed effect is that of scat-tering or 19 increased opacity as the polymers A and B intermix. However, 20 with continued application of voltagè a sheet of A and a 21 sheet of B is formed on their respective electrodes.
A A
27 and the result is a clear or transparent cell since intermixing 28 is minimal.
29 In order to maximize scattering or intermixing, the polarity would have to be constantly switched. This explana-31 tion is consistent with the results obtained under various :1 OS~;S24 1 conditions, i.e. at first the cell produces scattering when 2 voltage is applied. As the voltage is left on -the cell 3 eventually clears and remains mostly clear as long as the 4 voltage is on. When the potential is reversed, the cell again becomes scattering and then clears.
6 In the case of the formaldehyde condensation pQlymers, 7 it is believe~ that the polymers contain different molecular 8 weight fractions, which have different solubility characteristics, g so that in effect two phases are obtained. This also is con-sistent with the observation that the formaldehyde condensa-11 tion polymers form 2 liquid layers on standing, with one of 12 the layers having an oil like appearance.
13 The following examples are given solely for purposes of 14 illustration and are not to be considered limitations on the invention, many variations of which are possible without 16 departing from the spirit or scope thereof.
18 A composition containing one part 3-vinyl-10-methyl 19 phenothiazine polymer and one part cellulose nitrate resin was added to 20 parts tetrahydrofuran solvent. A viscous 21 opalescent appearing solution was obtained. The solution was ~2 placed in a thin cell consisting of two glass plates each 23 coated with a thin transparent elect~ically conductive layer 24 of tin oxide. The glass plates, which were separated by a 75 micron mylar spacer, were arranged in a parallel plate electrode 26 configuration and were connected to a power supply. The 27 solution in the thin cell had a very slightly hazy appearance 28 prior to application of voltage across the cell. When a 29 potential of about 10 volts was applied, a highly scattering ~05/E;S2~
1 opa~ue layer was obtained. The layer was made clear or trans-2 parent by applying a~short pulse of voltage opposite in 3 polarity t~ that used to produce the scattering.
4 The addition of a small amount (~10~ by weiyht of total solids) of carbon tetrabromide was used to make the layer 6 beam addressable. That is, the layer contain~d in the cell 7 cou~d be imaged with light so ~hat the portions of the cell a receiving light were clear or transparent and the areas not g receiving light were opaque or scattering.
10 - EX~lPLE ~I -11 A solution containing 30 percent dibenzothiophene formal-12 dehyde condensation polymer in methyl ethyl ke~one was placed 13 in a matrix cell consisting o~ a glass plate with 7 horizontal 14 transparent electrically conductive strips of indium oxide, a 25 micron Myia~ spacer and another glass plate with 5 vertical 16 conductive strips of indium oxide. (Mylar is duPont's brand 17 of polyethylene terephthalate.) This formed a 5 x 7 matrix 18 which was driven by scanning through the 7 lines one at a time 19 . with an applied voltage. The 5 vertical lines had either a select voltage or non-select voltage with reference to the 21 scan line voltaye.
2~ For exampl~, the voltage on the scanned line miyht be ~3 2V and the selected line at -V giving 2V-(-V) or 3V at that 24 cross point twhere V is a threshold voltage below wllich no chan-ge is observed). This 3:1 matrix scheme was used to drive 26 the cell. At a 3V of 10 volts a 25 micron cell showed charac-27 ters with fairly good scatteri~g density in the character area.
28 A 75 micron cell driven at a 3V of 12 volts showed characters 29 with good contrast (opaque in the cross point areas clear in the backyround areas).
*Registered Trade Mark ~C~5~52~
2 Dibenzothiophene formaldehyde condensation polymer (30 parts) 3 was added to methy' ethyl ketone (70 parts) and was placed 4 between conductive tin oxide coated glass plates separated by a 37 micron Mylar spacer. A potential of 2 volts was applied 6 across the cell. No scattering or change in appearance was ob-7 served. The voltage was increased to 4 volts. Again no scatter-8 ing was observed. When 6 volts were applie~ the cell was driven 9 to an opaque light scattering ~tate. This demonstrates a threshold effect or point below which no change is observed.
11 EXAMPI,E IV
1~ A solution containing 30~ by weight of dibenzothiophene 13 formaldehyde condensation polymer in methyl ethyl ketone was 14 placed between transparent conductive tin oxide coated glass plates. The glass plates were separated by a 37 micron Mylar 16 spacer. A 25 volt potential was placed across the cell and the 17 cell was simultaneously exposed to a pattern of ultraviolet 18 light. The areas of the cell receiving the ultraviolet light 19 became opaque or l~ght scattering while the background areas were clear. The image was erased by reversing the polarity of 21 the applied voltage.
23 A cell was constructed of a pair of electrically conduc-~4 tive tin oxide coated glass plates arranged parallel. The plates were separated by a 12 micron Mylar spacer. A composi-26 tion of 5 parts dibenzothiophene-dibenzofuran formaLdehyde 27 terpolymer, 5 parts methyi ethyl ketone and 2 parts acetone 28 was added to the space between the conductive electrodes.
29 A potential of 2 volts applied across the cell was insuffi-cient to produce scattering. Very slight scattering was _g_ ~0565~
1 observed at 4 volts while very good scatkering was obs~rved 2 with 6 volts.
4 A terpolymer of dibenzothiophene dibenzofuran formalde-hyde was added to dimethylformamide at a ratio of 3 parts 6 polymer to 7 parts solvent. The solution was added to a cell 7 constructed as in Example V. A potential up to 4 volts 8 was insufficient to pxoduce scattering. Slight scattering g was observed with 6 volts, and good scattering with 8 volts applied across the cell.
12 A solution of 2 parts oellulose nitrate, 5 parts styrene-13 2-vinyl pyridine copolymer, 14 parts tetrahydrofuran and 14 14 parts methyl ethyl ketone was placed in a cell constructed as described in Example III. The solution was driven to a 1~ scattering state with the application of 20V. The solution 17 was cleared by applying voltage opposite in polarity.
19 A solution of 2 parts cellulose nitrate, 5 parts l-vinyl naphthalene and 28 parts methyl ethyl ketone was added to a 21 cell as in Example VII. Weak scattering was produced when a 22 potential of 20 volts was used to drive the cell.
.
2~ One part cellulose nitrate, 6 parts dibenzothiophene dibenzofura~ formaldehyde terpolymer and 28 parts methyl ethyl 26 ketone were added to a cell as in Example III. The cell was 27 driven to a s~attering state by application of 20 volts.
29 Two parts polyvinylcarbaæole, 1 part cellulose nitrate and 27 parts tetrahydrofuran were added to a cell as in ~)56S; :4 1 Example III. The cell was driven to a scattering state by 2 application of 15 volts.
3 EXAMP~E XI
4 A solution consisting of 1 part Vitel PE222 ~a linear saturated polyester polymer from the Goodyear Tire and Rubber 6 Co.) and 2 parts polyvinylcarbazole in tetrahydrofuran 7 (12% solids by wei~ht) were added to a cell. The cell consisted 8 of parallel conductive coated glass plates separated by a g 19 micron Mylar spacer. The cell was driven to a scatteriny state by the application o~ 30 volts. The cell was cleared 11 by reversing the polarity of applied voltage.
13 A composition containing 3 parts polyvinyl carbazole, 1~ 1 part cellulose nitrate, .03 parts 1',3',3'-trimethyl~6-nitrospiro [2H-l-benzopyran-2,2'-indoline, and 40 parts tetra-16 hydrofuran was added to a cell of transparent tin oxide coated 17 glass plates separated by a 19 micron Mylar spacer. A 15 volt 18 potential was applied across the cell while the cell was exposed 19 to a pattern of light. The background areas were transparent 2~ or clear, while the exposed areas had a frosty or scattering 21 appearance. The image was erased by reversing the polarity 22 and the process was repeated again producing an image in the 23 form of clear and scattering areas.
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:-
1. An apparatus for displaying a visible image, said apparatus comprising two substantially parallel planar electrodes at least one of which is transparent, and, contained between said electrodes, a solution in liquid of at least two polymers, at least one of which is selected from the group consisting of cellulose nitrate, polyester, polyvinylcarbazole and formaldehyde condensation polymers with the other polymer being selected from the group consisting of polymethylene -N-ethyl carbazole polymer, 3-vinyl-10-methyl phenothiazine poly-mer, styrene copolymerized with 2-vinyl pyridine, dibenzothio-phene condensation polymer with formaldehyde, 1-vinyl naphtha-lene polymer, formaldehyde condensation polymer with dibenzo-thiophene and dibenzofuran, polyvinylcarbazole, polyester and polystyrene, and with the liquid being selected from the group consisting of tetrahydrofuran, methyl ethyl ketone, acetone, dimethyl formamide and mixtures thereof.
2. An apparatus as claimed in claim 1 wherein a polymer is photoconductive.
3. An apparatus as claimed in claim 1 wherein the transparent electrode is glass coated with tin oxide.
4. An apparatus as claimed in claim 1 wherein a polymer is cellulose nitrate.
5. An apparatus as claimed in claim 1 wherein a polymer is a formaldehyde condensation polymer.
6. A process for forming a visible display image, said process comprising applying an electrical voltage to a solution in liquid of a mixture of at least two polymers at least one of which is selected from the group consisting of cellulose nitrate, polyester, polyvinylcarbazole, and formaldehyde condensation polymers, with the other polymer being selected from the group consisting of polymethylene-N-ethyl carbazole polymer, 3-vinyl-10-methyl phenothiazine polymer, styrene copolymer-ized with 2-vinyl pyridine, dibenzothiophene condensation polymer with formaldehyde, 1-vinyl naphthalene polymer, for-maldehyde condensation polymer with dibenzothiophene and dibenzofuran, polyvinylcarbazole, polyester and polystyrene, and with the liquid being selected from the group consisting of tetrahydrofuran, methyl ethyl ketone, acetone, dimethyl formamide and mixtures thereof, said voltage being applied in an imagewise manner to the polymer solution contained between two substantially parallel planar electrodes, at least one of which is transparent.
7. A process as claimed in claim 6 wherein a polymer is photoconductive and exposed to light in an imagewise manner simultaneously with the application of the electrical voltage.
8. A process as claimed in claim 6 wherein the voltage is applied in an imagewise manner by means of matrix address-ing.
9. A process as claimed in claim 6 wherein a polymer is cellulose nitrate.
10. A process as claimed in claim 6 wherein a polymer is a formaldehyde condensation polymer.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/638,398 US4004849A (en) | 1975-12-08 | 1975-12-08 | Display apparatus and process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1056524A true CA1056524A (en) | 1979-06-12 |
Family
ID=24559868
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA267,320A Expired CA1056524A (en) | 1975-12-08 | 1976-12-07 | Displays using liquid mediums |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US4004849A (en) |
| JP (1) | JPS5943723B2 (en) |
| CA (1) | CA1056524A (en) |
| GB (1) | GB1538504A (en) |
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| US4193670A (en) * | 1977-11-08 | 1980-03-18 | American Cyanamid Company | Electrochromic devices having protective interlayers |
| FR2458827A1 (en) * | 1979-06-13 | 1981-01-02 | Thomson Csf | ELECTROOPTIC ELECTRIC BIREFRINGENCE DEVICE COMPRISING A POLARIZED POLYMER |
| FR2504290B1 (en) * | 1981-04-21 | 1986-08-01 | Hopkinson Associates Inc | ELECTROSENSITIVE METHOD AND MEDIUMS FOR RECORDING SIGNALS AND IMAGES |
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| US6829077B1 (en) | 2003-02-28 | 2004-12-07 | Silicon Light Machines, Inc. | Diffractive light modulator with dynamically rotatable diffraction plane |
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| JP6413371B2 (en) * | 2014-02-07 | 2018-10-31 | 東ソー株式会社 | Arylamine copolymer, production method thereof and use thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3694246A (en) | 1969-06-24 | 1972-09-26 | Ncr Co | Method of using display device utilizing polymer-polymer miscibilities |
| US3702724A (en) * | 1971-10-13 | 1972-11-14 | Atomic Energy Commission | Ferroelectric ceramic plate electrooptical light scattering device and method |
-
1975
- 1975-12-08 US US05/638,398 patent/US4004849A/en not_active Expired - Lifetime
-
1976
- 1976-11-16 GB GB47653/76A patent/GB1538504A/en not_active Expired
- 1976-11-26 JP JP51141362A patent/JPS5943723B2/en not_active Expired
- 1976-12-07 CA CA267,320A patent/CA1056524A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5943723B2 (en) | 1984-10-24 |
| JPS5269879A (en) | 1977-06-10 |
| US4004849A (en) | 1977-01-25 |
| GB1538504A (en) | 1979-01-17 |
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