ilmte States Patent 1191
`United States Patent
`1191
`Muto et a1.
`Muto et al.
`
`3,871,746
`1111
`3,871,746
`1111
`[45] Mar. 18, 1975
`[45] Mar. 18, 1975
`
`[54] LlQUlD CRYSTAL CELL
`[541 LlQUlD CRYSTAL CELL
`..
`.
`1751
`Invenws Rmnro Mute: sungemasa puma,
`__
`_
`[75] lnvemmsl RYuJ'" Mum; sh'gemasa Furuuchl’
`bOEh 0f .YOkOhama: HWOS'“
`both of Yokohama; ""051"
`Uklhashl, Tokyo; Katsuo Uchuima;
`Uklhashl, Tokyo; Katsuo Uchulma;
`Hiromichi Nishimura, both of
`l-lllromichi Nishimura, both of
`Yokohama, an of Japan
`Yokohama, an of Japan
`,
`.
`,
`.
`[73] Ass1gnee: Asahl Glass Company, Ltd., Tokyo,
`[73] Ass1gnee: Asahl Glass Company, Ltd., Tokyo,
`Japan
`Japan
`6, 1973
`Ft] d2
`22
`une 6 1973
`Filed:
`22
`,
`J
`1
`[
`June
`i e
`i
`[
`l2” APPI- NO-1 3679527
`i211 APPI- NO-I 367,527
`
`3,594,126
`3,594,126
`,
`.
`3,238.33;
`,
`,
`3,625,591
`3,625,591
`3,647,279
`3,647,279
`3,661,444
`3,661,444
`3,765,747
`3,765,747
`3,781,087
`3,781,087
`
`7/1971
`Ferguson ct al. ............... 23/230 LC
`7/1971
`Ferguson ct 111. ............. .. 23/230 LC
`9
`'
`'
`..................
`32:32:???...................... 338228 t5
`13:93!
`9
`H '
`'
`................... .. 350 160 LC
`.................... .. 230/230 LC
`Freiser .......................... 350/160 LC
`12/1971
`Freiser ..................... .. 350/160 LC
`12/1971
`Sharpless et al .............. 350/160 LC
`3/1972
`3/1972 Sharpless et al ......... .. 350/160 LC
`5/1972 Matthies ....................... 350/160 LL
`5/1972
`Matthies .................. .. 350/160 LL
`10/1973
`Pankratz et al ............... 350/160 LC
`10/1973
`Pankratz et al .......... .. 350/160 LC
`12/1973
`Nagasaki et a1. ............. 350/160 LC
`12/1973
`Nagasaki et a1. ........... .. 350/160 LC
`
`Primary Examiner—l-larold Ansher
`Primary Examiner—Harold Ansher
`Attorney, Agent, or Firm—Oblon, Fisher, Spivak,
`Attorney, Agent, or Firm—-Oblon, Fisher, Spivak,
`McClelland & Maier
`McClelland & Maier
`
`[30]
`[30]
`
`Foreign Application Priority Data
`Foreign Application Priority Data
`June 6, 1972
`Japan ................................ 47-55681
`June 6, 1972
`Japan .............................. .. 47-55681
`
`[57]
`[57]
`
`ABSTRACT
`ABSTRACT
`
`1521 U-S- Cl- -------- -- 350/l60 LC, 23/230 LC, 161/51
`l52] U-S- 0- .......... 350/160 LC. 23/230 LC, 161/51
`161/45, 161/189, 161/410. 252/403 LC
`161/45,161/189,161/410,252/408 LC
`llll. Cl. ............................................ .. G02f 1/34
`51 l
`“it. Cl. .............................................. GOZf “34
`[51 I
`s81 Fleld 01 Search -------- -- 350/16O LC; 23/230 LC;
`Fleld of Search .......... 350/160 LC; 23/230 LC;
`252/408 LC; 161/45, 139, 11 58614084110
`252/408 LC; 161/45, 189~ 1, 58614084110
`
`l 56]
`i 56]
`
`3,44 l ,5 I 3
`_‘1_44l,5|3
`
`References Cited
`References Cited
`UNlTED STATES PATENTS
`UNlTED STATES PATENTS
`4/1969 Woodmansee ................. 23/230 LC
`4/1969 Woodmansee ............... .. 23/230 LC
`
`A liquid crystal cell which is formed from a pair of
`A liquid crystal cell which is formed from a pair of
`plates, at least one of which is transparent, and
`plates, at
`least one of which is
`transparent, and
`wherein the space between said plates is ?lled with a
`wherein the space between said plates is filled with a
`liquid crystal material and wherein said plates are
`liquid crystal material and wherein said plates are
`sealed with a sealant made of tetrafluoroethylene
`sealed with a sealant made of tetrafluoroethylene-
`ethylene-copolymer or a chlorotri?uoroethylene
`ethylene-copolymer
`or
`a
`chlorotrifluoroethylene-
`ethylene-copolymer.
`ethylene-copolymer.
`
`10 Claims, 3 Drawing Figures
`10 Claims, 3 Drawing Figures
`
`2
`mas “A /3
`4
`3
`4 ~12
`
`
`
`IVI LLC EXHIBIT 2013
`
`XILINX V. IVI LLC
`
`Inter Partes Review Case 2013—001 12
`
`

`

`f’MENTEDHARI 8l975
`
`3.871.746
`
`FlG.l
`
`
`
`

`

`1
`1
`LIQUID CRYSTAL CELL
`LIQUID CRYSTAL CELL
`BACKGROUND OF THE INVENTION
`BACKGROUND OF THE INVENTION
`l. Field of the Invention
`l. Field of the Invention
`This invention relates to a liquid crystal cell. More
`This invention relates to a liquid crystal cell. More
`particularly. it relates to a liquid crystal cell which is
`particularly. it relates to a liquid crystal cell which is
`chemically. mechanically and electrically stable, is her
`chemically. mechanically and electrically stable, is her-
`metically sealed and has a uniform space between the
`metically sealed and has a uniform space between the
`front and back plates.
`front and back plates.
`2. Description of the Prior Art
`2. Description of the Prior Art
`Heretofore, liquid crystal cells which are used for op-
`Heretofore, liquid crystal cells which are used for op
`tical display devices or light valves have been prepared
`tical display devices or light valves have been prepared
`by sealing two plates with a sealant. The plates are sep-
`by sealing two plates with a sealant. The plates are sep
`arated by a spacer to hold the plates at a predetermined
`arated by a spacer to hold the plates at a predetermined
`distance from one another. Usually liquid crystal inor
`distance from one another. Usually liquid crystal inor-
`ganic sealants have been used for this purpose, such as
`ganic sealants have been used for this purpose, such as
`low-melting glass frit or an organic bonding agent such
`low-melting glass frit or an organic bonding agent such
`as an epoxy type sealant or heat sealing type film. Be-
`as an epoxy type sealant or heat sealing type ?lm. Be
`cause the sealant is an important factor in determining
`cause the sealant is an important factor in determining
`the lifetime of the liquid crystal cell, it is important that
`the lifetime of the liquid crystal cell, it is important that
`the sealant have a sufficient long lifetime. However,
`the sealant have a sufficient long lifetime. However,
`completely satisfactory sealants have not been re
`completely satisfactory sealants have not been re-
`ported.
`ported.
`Because ofthe difficulties encountered in attempts to
`Because ofthe difficulties encountered in attempts to
`find a suitable sealant for liquid crystal cells, practical
`find a suitable sealant for liquid crystal cells, practical
`utilization of optical display devices or light valves
`utilization of optical display devices or light valves
`using a liquid crystal material has not been realized. It
`using a liquid crystal material has not been realized. It
`has been found that when an inorganic sealant is used
`has been found that when an inorganic sealant is used
`in the conventional method of sealing the cell, fewer
`in the conventional method of sealing the cell, fewer
`adverse affects are found which influence the life of liq-
`adverse affects are found which in?uence the life of liq
`uid crystal cell than when an organic sealant is used.
`uid crystal cell than when an organic sealant is used.
`However, inorganic sealants complicate the sealing op
`However, inorganic sealants complicate the sealing op-
`eration since the workability of such sealants is low. On
`eration since the workability of such sealants is low. On
`the other hand, when an organic sealant is used, sealing
`the other hand, when an organic sealant is used, sealing
`operations are comparatively easy. However, organic
`operations are comparatively easy. However, organic
`sealants such as epoxy sealants adversely affect the liq
`sealants such as epoxy sealants adversely affect the liq—
`uid crystal material of the cell causing deterioration of
`uid crystal material of the cell causing deterioration of
`the liquid crystal material through the formation of
`the liquid crystal material
`through the formation of
`bubbles or by discoloration.
`bubbles or by discoloration.
`Previously, heat sealing films of such materials as ny
`Previously, heat sealing films of such materials as ny-
`lon, epoxy, butyral, or polyethylene have been pro
`lon, epoxy, butyral, or polyethylene have been pro-
`posed in order to seal the cells. However, the known
`posed in order to seal the cells. However, the known
`heat sealing films have the disadvantage of having high
`heat sealing films have the disadvantage of having high
`moisture permeability and, accordingly the moisture
`moisture permeability and, accordingly the moisture
`content of the liquid crystal material is increased by
`content of the liquid crystal material is increased by
`permeation through the film over a sustained period of
`permeation through the film over a sustained period of
`time. Bubbles thereby tend to form and the operability
`time. Bubbles thereby tend to form and the operability
`of the liquid crystal meterial deteriorates.
`of the liquid crystal meterial deteriorates.
`A need, therefore. exists for a sealant for application
`A need, therefore, exists for a sealant for application
`in liquid crystal cells which maintains the integrity of
`in liquid crystal cells which maintains the integrity of
`the seal between the plates of the cell for long periods
`the seal between the plates of the cell for long periods
`of time. and which does not adversely affect the cell
`of time. and which does not adversely affect the cell
`upon contact with the liquid crystal material.
`upon contact with the liquid crystal material.
`SUMMARY OF THE INVENTION
`SUMMARY OF THE INVENTION
`Accordingly. one object of this invention is to pro
`Accordingly. one object of this invention is to pro-
`vide a liquid crystal cell which is chemically, mechani
`vide a liquid crystal cell which is chemically, mechani—
`cally and electrically stable and is hermetically sealed.
`cally and electrically stable and is hermetically sealed.
`Another object of this invention is to provide a liquid
`Another object of this invention is to provide a liquid
`crystal cell which has a uniform thickness between the
`crystal cell which has a uniform thickness between the
`plates of the cell within which is sealed the liquid crys
`plates of the cell within which is sealed the liquid crys-
`tal material.
`tal material.
`Brie?y. these objects and other objects of this inven
`Briefly. these objects and other objects of this inven-
`tion as hereinafter will become readily apparent can be
`tion as hereinafter will become readily apparent can be
`attained by the use of a tetra?uoroethylene-ethylene
`attained by the use of a tetrafluoroethylene-ethylene
`copolymer, or a chlorotrifuloroethylene-ethylene co
`copolymer, or a chlorotrifuloroethylene-ethylene co-
`polymer as a sealant for the opposing plates of a liquid
`polymer as a sealant for the opposing plates of a liquid
`
`40
`
`45
`45
`
`50
`
`55
`55
`
`60
`
`65
`65
`
`3,871,746
`3,871,746
`
`£11
`
`10
`
`15
`15
`
`20
`
`25
`25
`
`30
`30
`
`35
`35
`
`2
`2
`crystal cell. Preferably a spacing element, which is
`crystal cell. Preferably a spacing element, which is
`placed between the plates of the cell, is incorporated in
`placed between the plates of the cell, is incorporated in
`the sealant of the tetrafluoroethylene-ethylene copoly
`the sealant of the tetrafluoroethylene-ethylene copoly-
`mer or the chlorotrifluoro-ethylene-ethylene copoly
`mer or the chlorotrifluoro-ethylene-ethylene copoly—
`mer.
`mer.
`BRIEF DESCRIPTION OF THE DRAWINGS
`BRIEF DESCRIPTION OF THE DRAWINGS
`A more complete appreciation of the invention and
`A more complete appreciation of the invention and
`many of the attendant advantages thereof will be
`many of the attendant advantages thereof will be
`readily obtained as the same becomes better under
`readily obtained as the same becomes better under-
`stood by reference to the following detailed description
`stood by reference to the following detailed description
`when considered in connection with the accompanying
`when considered in connection with the accompanying
`drawings, wherein:
`drawings, wherein:
`FIG. 1 is a plane view ofa front plate of a liquid crys
`FIG. 1 is a plane view ofa front plate of a liquid crys-
`tal cell which shows via the shaded regions where the
`tal cell which shows via the shaded regions where the
`sealant of the tetra?uomethylene-ethylene copolymer
`sealant of the tetrafluomethylene-ethylene copolymer
`is placed;
`is placed;
`FIG. 2 is a plane view of a liquid crystal cell; and
`FIG. 2 is a plane view of a liquid crystal cell; and
`FIG. 3 is a sectional view taken along the line A—A
`FIG. 3 is a sectional view taken along the line A-A
`of FIG. 2 which shows the cell filled with a liquid crys-
`of FIG. 2 which shows the cell ?lled with a liquid crys
`tal material.
`tal material.
`DETAILED DESCRIPTION OF THE PREFERRED
`DETAILED DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`EMBODIMENTS
`The tetra?uoroethylene-ethylene copolymer (herein
`The tetrafluoroethylene-ethylene copolymer (herein-
`after referred to as C2F4-C2H4 copolymer) and the chlo-
`after referred to as C2F4-C2H4 copolymer) and the chlo
`rotrifluoroethylene~ethylene copolymer (hereinafter
`rotrifluoroethylene~ethylene copolymer
`(hereinafter
`referred to as C2ClF3-C2H.1 copolymer) used in this in-
`referred to as C2ClF,»,-C2H4 copolymer) used in this in
`vention exhibit no reactivity with liquid crystal materi
`vention exhibit no reactivity with liquid crystal materi-
`als and have low moisture permeability. In addition, the
`als and have low moisture permeability. In addition, the
`copolymers have excellent chemical and mechanical
`copolymers have excellent chemical and mechanical
`properties as well as electrical properties particularly
`properties as well as electrical properties particularly
`dielectric properties. Moreover, the copolymers can be
`dielectric properties. Moreover, the copolymers can be
`satisfactorily molded and also the overall adhesiveness
`satisfactorily molded and also the overall adhesiveness
`to the plate is improved by the use of the C2F4-C2H, co
`to the plate is improved by the use of the C2F4-C2H, co-
`polymer or the C21F3’C2H4 copolymer.
`,
`polymer or the C2lF3-C2H4 copolymer.
`,
`The optimum C2F4-C2H4 copolymers or CQCIFQ-CZH,
`The optimum C2F4-C2H4 copolymers or CgCng-CZH,
`copolymers for this invention are those which have a 60
`copolymers for this invention are those which have a 60
`— 30 mole percent C2I-I4 component content in the co-
`— 30 mole percent C2I-I4 component content in the co
`polymers and have a volumetric ?ow rate, as defined
`polymers and have a volumetric flow rate, as defined
`below, of 30 — 300 mm3/sec. the term “volumetric flow
`below, of 30 — 300 mms/sec. the term “volumetric flow
`rate” is defined as the extrusion of a one gram sample
`rate” is de?ned as the extrusion of a one gram sample
`of copolymer by a flow tester at a predetermined tem
`of copolymer by a flow tester at a predetermined tem-
`perature from a nozzle having a diameter of 1 mm and
`perature from a nozzle having a diameter of 1 mm and
`a land of 2 mm under a pressure of 30 kg/cmz. The vol-
`a land of 2 mm under a pressure of 30 kglcmz. The vol
`ume of the molten polymer extruded in 1 second is de-
`ume of the molten polymer extruded in 1 second is de
`fined as the volumetric flow rate, and the unit
`is
`fined as the volumetric ?ow rate, and the unit is
`mmalsecond. The predetermined temperature is se
`mm3/second. The predetermined temperature is se-
`lected over a range so that good moldability is ob-
`lected over a range so that good moldability is ob
`tained. The temperature selected is in the range be-
`tained. The temperature selected is in the range be
`tween the initiation of flow of the copolymer and the
`tween the initiation of ?ow of the copolymer and the
`decomposition temperature of the copolymer. Prefera
`decomposition temperature of the copolymer. Prefera-
`bly the temperature selected is near the flow initiation
`bly the temperature selected is near the flow initiation
`temperature and is in the range of 260°-360°C for the
`temperature and is in the range of 260°—360°C for the
`QR. - C2H4 copolymer and in the range of 240°—320°C
`QR, - CZH.l copolymer and in the range of 240°-320°C
`for the CzCng-C2H4 copolymer. Of course, tempera-
`for the C2ClF3-C2H4 copolymer. Of course, tempera
`tures greater than the thermal decomposition tempera
`tures greater than the thermal decomposition tempera-
`ture of the copolymers are avoided.
`ture of the copolymers are avoided.
`The liquid crystal cell of this invention has excellent
`The liquid crystal cell of this invention has excellent
`chemical, mechanical and electrical properties and es-
`chemical, mechanical and electrical properties and es
`pecially possesses low moisture permeability. It also
`pecially possesses low moisture permeability.
`It also
`achieves high reliability with excellent moldability and
`achieves high reliability with excellent moldability and
`adhesiveness. These properties permit hermetic sealing
`adhesiveness. These properties permit hermetic sealing
`of any shape and size of liquid crystal cell with the co
`of any shape and size of liquid crystal cell with the co-
`polymers of this invention. Thus, simple and practical
`polymers of this invention. Thus, simple and practical
`sealing of the cells can be accomplished with the C2F4
`sealing of the cells can be accomplished with the C2F4
`- C2H4 copolymer or the C2C1F3 - C2H4 copolymer.
`- C2H4 copolymer or the CZCIFQ - C2H4 copolymer.
`
`

`

`3
`3
`The content of the ethylene component in the C2F4
`The content of the ethylene component in the QR,-
`CZH4 copolymer or the C2CIF3 - CZH4 copolymer is
`CZH4 copolymer or the C2C1F3 - C2H4 copolymer is
`preferably from 30 — 60 mole percent. If the tetra?uor
`preferably from 30 - 60 mole percent. If the tetrafluor-
`oethylene content or the chlorotri?uoroethylene con
`oethylene content or the chlorotrifluoroethylene con-
`tent of the copolymer is too low. the chemical resis-
`tent of the copolymer is too low, the chemical resis
`tance and the thermal stability of the copolymer are in-
`tance and the thermal stability of the copolymer are in
`sufficient. On the other hand, if the tetrafluoroethylene
`suf?cient. On the other hand, if the tetra?uoroethylene
`content or the chlorotrifluoroethylene content is too
`content or the chlorotrifluoroethylene content is too
`high, the moldability and adhesiveness of the copoly
`high, the moldability and adhesiveness of the copoly-
`mers decrease. It is especially preferred to use copoly
`mers decrease. It is especially preferred to use copoly-
`mers containing an ethylene content of 40 - 55 mole
`mers containing an ethylene content of 40 - 55 mole
`percent.
`percent.
`The volumetric flow rate of the copolymer is limited
`The volumetric ?ow rate of the copolymer is limited
`from the viewpoint of moldability and is usually in the
`from the viewpoint of moldability and is usually in the
`range of 30 —— 300 mm3/second, especially 4O — 160
`range of 30 - 300 mma/second, especially 40 - 160
`mm3/second. If the volumetric flow rate is outside of
`mmslsecond. If the volumetric ?ow rate is outside of
`this range, the moldability, adhesiveness, mechanical
`this range, the moldability, adhesiveness, mechanical
`strength dielectric constant, thermal stability and the
`strength dielectric constant, thermal stability and the
`like decrease.
`like decrease.
`The C2F4-C2H4 copolymer used in this invention has
`The C2F,-C2H., copolymer used in this invention has
`a flow initiation temperature of about 260 — 300°C and
`a flow initiation temperature of about 260 — 300°C and
`a thermal decomposition temperature of about 340 —
`a thermal decomposition temperature of about 340 -
`360°C. The optimum C2F4-C2H4 copolymers used in
`360°C. The optimum C2F4—C2H4 copolymers used in
`this invention have flow initiation temperatures ranging
`this invention have flow initiation temperatures ranging
`from 270 ~ 290°C and a thermal decomposition tem-
`from 270 -- 290°C and a thermal decomposition tem
`perature range of 345 — 355°C. The heat sealing tem-
`perature range of 345 — 355°C. The heat sealing tem
`perature range between the ?ow initiation temperature
`perature range between the flow initiation temperature
`of the particular copolymer used and its thermal de
`of the particular copolymer used and its thermal de-
`composition temperature is usually in the range of
`composition temperature is usually in the range of
`260°— 360°C, especially 270° — 345°C. The CgCng-
`260°- 360°C, especially 270° — 345°C. The CQCIFa‘
`Czl-l, copolymer used in this invention has a flow initia
`C2H4 copolymer used in this invention has a flow initia-
`tion temperature of about 240° — 270°C and a thermal
`tion temperature of about 240° - 270°C and a thermal
`decomposition temperature of 310° — 340°C. The opti-
`decomposition temperature of 310° - 340°C. The opti
`mum C2CIF3'C2H4 copolymer used in this invention has
`mum C2ClF3-C2H, copolymer used in this invention has
`a flow initiation temperature of 250° — 265°C and a
`a ?ow initiation temperature of 250° — 265°C and a
`thermal decomposition temperature of 320° — 335°C.
`thermal decomposition temperature of 320° - 335°C.
`Usually, the temperature for heat sealing of the cells is
`Usually, the temperature for heat sealing of the cells is
`in the range of 240° - 340°C, especially 250° - 320°C.
`in the range of 240° - 340°C, especially 250° - 320°C.
`The C2F4-C2H4 copolymer or the CzClFs-C2H4 co-
`The C2F,-C2H4 copolymer or the C2ClF3-C2H4 co
`polymer can be prepared by various polymerization
`polymer can be prepared by various polymerization
`procedures such as catalytic emulsion polymerization,
`procedures such as catalytic emulsion polymerization.
`suspension polymerization, catalytic solution polymer
`suspension polymerization, catalytic solution polymer-
`ization. radiation induced polymerization, or the like.
`ization, radiation induced polymerization, or the like.
`Generally the chlorotrifluoroethylene-ethylene mole
`Generally the chlorotrifluoroethylene-ethylene mole
`ratio and the tetra?uoroethylene-ethylene mole ratio
`ratio and the tetrafluoroethylene-ethylene mole ratio
`range from 40/60 to 70/30. It is also possible to add a
`range from 40/60 to 70/30. It is also possible to add a
`small amount of another comonomer such as propy-
`small amount of another comonomer such as propy
`lene, isobutylene, vinyl?uoride. hexa?uoropropylene,
`lene, isobutylene, vinylfluoride. hexafluoropropylene,
`per?uorovinyl ether or a modifier in the polymerization
`perfluorovinyl ether or a modifier in the polymerization
`of tetra?uoroethylene and ethylene.
`of tetrafluoroethylene and ethylene.
`In this invention, the liquid crystal cell plates can be
`In this invention, the liquid crystal cell plates can be
`made of any suitable inorganic material such as glass,
`made of any suitable inorganic material such as glass,
`ceramics or metal, or any suitable organic material se-
`ceramics or metal, or any suitable organic material se
`lected from the broad group of plastic materials. The
`lected from the broad group of plastic materials. The
`front cell plate is usually a transparent material such as
`front cell plate is usually a transparent material such as
`glass, and the back plate can be either transparent or
`glass, and the back plate can be either transparent or
`opaque. When a field effect liquid crystal material is
`opaque. When a field effect liquid crystal material is
`placed in the liquid crystal cell, the plates ofthe cell are
`placed in the liquid crystal cell, the plates ofthe cell are
`usually coated with an electroconductive ?lm, prefera
`usually coated with an electroconductive film, prefera-
`bly a transparent electro-conductive film such as Sn02
`bly a transparent electro—conductive film such as Sn02
`and/0r lnzOa, by a vacuum deposition method. It is also
`and/or In203, by a vacuum deposition method. It is also
`possible to use plates coated with an opaque electro~
`possible to use plates coated with an opaque electro—
`conductive
`film such as aluminum. The electro—
`conductive film such as aluminum. The electro
`conductive film can be completely coated over the
`conductive film can be completely coated over the
`plates or it can be placed on the plates in appropriate
`plates or it can be placed on the plates in appropriate
`patterns such as numeral ?gures, X-Y matrices for
`patterns such as numeral figures, X-Y matrices for
`showing letters, figures, pictures or the like.
`showing letters, figures, pictures or the like.
`
`10
`10
`
`15
`
`20
`20
`
`25
`25
`
`30
`30
`
`35
`35
`
`40
`40
`
`45
`45
`
`50
`50
`
`55
`55
`
`60
`60
`
`65
`65
`
`3,871,746
`3,871,746
`
`4
`4
`1n the preparation of the liquid crystal cell of this in
`In the preparation of the liquid crystal cell of this in-
`vention, the C2F4—C2H4 copolymer or the CzClFa-C2H4
`vention, the C2F4-C2H4 copolymer or the C2ClF3-C2H4
`copolymer is coated over those portions of one of the
`copolymer is coated over those portions of one of the
`cell plates which are most appropriate for sealing such
`cell plates which are most appropriate for sealing such
`as the peripheral areas of the plate in any appropriate
`as the peripheral areas of the plate in any appropriate
`thickness or shape. and the other plate is applied to the
`thickness or shape, and the other plate is applied to the
`coated plate. The two plates are heated at 240° — 360°C
`coated plate. The two plates are heated at 240° - 360°C
`under pressure, to complete the fabrication of the liq
`under pressure, to complete the fabrication of the liq-
`uid crystal cell. In this invention, when the plates are
`uid crystal cell. In this invention, when the plates are
`heat-sealed with a copolymer film of about 50p. thick.
`heat-sealed with a copolymer film of about 50p. thick.
`the space between the cell plates can be maintained
`the space between the cell plates can be maintained
`within the range of 15 to 20;L. In order to uniformly
`within the range of 15 to 20#. In order to uniformly
`maintain the distance between the plates of the liquid
`maintain the distance between the plates of the liquid
`crystal cell at a predetermined thickness, a spacing ele
`crystal cell at a predetermined thickness, a spacing ele-
`ment is preferably placed between the plates with the
`ment is preferably placed between the plates with the
`C2F4-C2H4 copolymer or the CzClFa-CzH, copolymer.
`C2F4-C2H4 copolymer or the C2ClF3-C2H4 copolymer.
`By carefully selecting the amount of copolymer and the
`By carefully selecting the amount of copolymer and the
`thickness of the spacing element, any desired spacing
`thickness of the spacing element, any desired spacing
`between the plates of the cell can be achieved. Because
`between the plates of the cell can be achieved. Because
`the copolymer completely coats the entire surface area
`the copolymer completely coats the entire surface area
`of the spacing element, the spacing element does not
`of the spacing element, the spacing element does not
`come in contact with the liquid crystal material so that
`come in contact with the liquid crystal material so that
`the liquid crystal material is not adversely affected by
`the liquid crystal material is not adversely affected by
`the spacing element. Thus, the workability of the com
`the spacing element. Thus, the workability of the com-
`pleted cell is good and mass production of liquid crystal
`pleted cell is good and mass production of liquid crystal
`cells can be readily achieved. The spacing element in
`cells can be readily achieved. The spacing element in-
`corporated in the cell with the copolymer of this inven
`corporated in the cell with the copolymer of this inven-
`tion, can be any suitable granular element such as glass
`tion, can be any suitable granular element such as glass
`beads made of soda—lime-silicate, ceramic beads made
`beads made of soda-lime-silicate, ceramic beads made
`of alumina, metal balls, plastic beads, glass fibers. me-
`of alumina, metal balls, plastic beads, glass fibers, me
`tallic fibers, whiskers and other fibrous elements, fine
`tallic ?bers, whiskers and other fibrous elements, fine
`ceramic fragments and the like. From the viewpoint of
`ceramic fragments and the like. From the viewpoint of
`the spacing element, optimum results are obtained
`the spacing element, optimum results are obtained
`when granular elements are used, especially glass beads
`when granular elements are used, especially glass beads
`or ceramic beads having diameters ranging from 5 ~
`or ceramic beads having diameters ranging from 5 —
`5011..
`5011..
`When the copolymer film is placed around the pe
`When the copolymer film is placed around the pe-
`ripheral areas of the completed cell, the two corners
`ripheral areas of the completed cell, the two corners
`which are not provided with inlet openings and which
`which are not provided with inlet openings and which
`are diagonally disposed are coated with a wide coating
`are diagonally disposed are coated with a wide coating
`of copolymer ?lm, or a small piece of copolymer film
`of copolymer film, or a small piece of copolymer film
`is placed at these corners. Thus, when the plates are
`is placed at these corners. Thus, when the plates are
`sealed by heat treatment, the sealing copolymer ?lm in
`sealed by heat treatment, the sealing copolymer film in
`these corners becomes smooth instead of remaining as
`these corners becomes smooth instead of remaining as
`sharp angles. This prevents the formation and subse
`sharp angles. This prevents the formation and subse-
`quent retention of gas bubbles in these corners and thus
`quent retention of gas bubbles in these corners and thus
`the lifetime of the liquid crystal material is maintained
`the lifetime of the liquid crystal material is maintained
`and an ideal liquid crystal cell results.
`and an ideal liquid crystal cell results.
`The drawings are schematic views which illustrate
`The drawings are schematic views which illustrate
`one embodiment of this invention. FIG.
`1 is a plane
`one embodiment of this invention. FIG. 1 is a plane
`view of the front plate 1 coated with a film 4 of C2F4-
`view of the front plate 1 coated with a ?lm 4 of CzFr
`C2H4 copolymer or C2CIF3H4 copolymer over the pe—
`C2H4 copolymer or C2CIF3H4 copolymer over the pe
`ripheral regions of the cell. FIG. 2 is a plane view of the
`ripheral regions of the cell. FIG. 2 is a plane view of the
`liquid crystal cell which is prepared by placing the back
`liquid crystal cell which is prepared by placing the back
`plate 7 over the front plate of FIG. 1, and compressing
`plate 7 over the front plate of FIG. 1, and compressing
`the plates together with a clamp while being heated at
`the plates together with a clamp while being heated at
`330°C for 20 minutes. FIG. 3 is a sectional view taken
`330°C for 20 minutes. FIG. 3 is a sectional view taken
`along the line A--A of FIG. 2.
`along the line A—A of FIG. 2.
`In this embodiment of the cell the front plate 1 con-
`In this embodiment of the cell the front plate 1 con
`sists of a glass plate 2 coated with an electrodconduc
`sists of a glass plate 2 coated with an electrodconduc-
`tive film 3 and the cell is ?lled with the liquid crystal
`tive film 3 and the cell is filled with the liquid crystal
`material 6 from the inlet 5 on the back plate 7. FIG. 2
`material 6 from the inlet 5 on the back plate 7. FIG. 2
`further shows the smoothness of the two corners diago-
`further shows the smoothness of the two corners diago
`nally disposed which are not provided with inlet open
`nally disposed which are not provided with inlet open—
`ings. In this embodiment, the corners were smoothed or
`ings. In this embodiment, the corners were smoothed or
`rounded by small pieces of the ?lm 8 which were
`rounded by small pieces of the film 8 which were
`placed in each corner before the cell was heat sealed.
`placed in each corner before the cell was heat sealed.
`
`

`

`5
`5
`Having now generally described the invention, a fur
`Having now generally described the invention, a fur-
`ther understanding can be attained by reference to cer
`ther understanding can be attained by reference to cer-
`tain specific Examples which are provided herein for
`tain specific Examples which are provided herein for
`purposes of illustration only and are not intended to be
`purposes of illustration only and are not intended to be
`limiting in any manner.
`limiting in any manner.
`EXAMPLE 1
`EXAMPLE 1
`A film of tetrafluoroethylene-ethylene copolymer
`A film of tetrafluoroethylene-ethylene copolymer
`(C2F4 : C2H4= 53 : 47, volumetric flow rate
`80
`(02F4 : C-,H,= 53 : 47, volumetric flow rate
`80
`mma/sec. at 300°C) with a thickness of 50p. was placed
`mma/sec. at 300°C) with a thickness of 50;; was placed
`over the peripheral areas of a front plate, and a back
`over the peripheral areas of a front plate, and a back
`plate was applied to the front plate. The combined
`plate was applied to the front plate. The combined
`plates were compressed with a clamp under a pressure
`plates were compressed with a clamp under a pressure
`of 1—2 kg/cm2 and were heated at 330°C for 20 minutes
`of 1-2 kg/cm2 and were heated at 330°C for 20 minutes
`to yield a sealed cell. The thickness of the cell was 15
`to yield a sealed cell. The thickness of the cell was 15