GB2131194A - Liquid crystal device - Google Patents
Liquid crystal device Download PDFInfo
- Publication number
- GB2131194A GB2131194A GB08328543A GB8328543A GB2131194A GB 2131194 A GB2131194 A GB 2131194A GB 08328543 A GB08328543 A GB 08328543A GB 8328543 A GB8328543 A GB 8328543A GB 2131194 A GB2131194 A GB 2131194A
- Authority
- GB
- United Kingdom
- Prior art keywords
- liquid crystal
- electrooptic device
- electrode plates
- background region
- region
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K19/00—Liquid crystal materials
- C09K19/52—Liquid crystal materials characterised by components which are not liquid crystals, e.g. additives with special physical aspect: solvents, solid particles
- C09K19/60—Pleochroic dyes
-
- 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
- G02F1/13—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 liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/133371—Cells with varying thickness of the liquid crystal layer
-
- 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
- G02F1/13—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 liquid crystals, e.g. single liquid crystal display cells
- G02F1/137—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 liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
- G02F1/13731—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 liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on a field-induced phase transition
- G02F1/13737—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 liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on a field-induced phase transition in liquid crystals doped with a pleochroic dye
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- Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Nonlinear Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Liquid Crystal (AREA)
- Mathematical Physics (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
Abstract
Liquid crystal device, especially a guest-host type liquid crystal device, having a display region and a background region, which comprises a pair of electrode plates juxtaposed with a space therebetween, and a liquid crystal layer disposed between the electrode plates and comprising a dichromatic colorant and a liquid crystal 5,5a takes a grandjean texture under no application of voltage. The thickness of the liquid crystal layer in the background region is made smaller than the spiral pitch of the grandjean texture. The surfaces of the electrode plates contacting the liquid crystal have been horizontally orientated. <IMAGE>
Description
SPECIFICATION
Electrooptic device
This invention relates to an electrooptic device, particularly to a guest-host type liquid crystal display device.
More particularly, it pertains to a guest-host type liquid crystal display device with the use of a phase transition type liquid crystal containing dichromatic colorant therein.
Recently, as a guest-host type liquid display device, researches and developments have been made about a system using a phase transition type liquid crystal. While this system has advantages of requiring no polarizerforincreasing contrast and giving a bright display face, its application has been limited only to a negative type display in which a display pattern is given by a colorless region against a colored background, because liquid crystal molecules which have been aligned to take the grandjean texture are erected vertically by application of a voltage to give display pattern.
Alternatively, as a method for giving a positive type display in which a colored pattern is given against a colorless background while retaining the brightness of the display face according to the phase transition system, a device as shown in Figure 1 has been reported wherein a pair of electrode plates 1 and 2 are so juxtaposed that the distance therebetween is made broader in the region corresponding to the display pattern and narrower in the other region and the whole surfaces are subjected to vertical orientation treatment thereby aligning the liquid crystal molecules 5 and the dichromatic colorant 6 substantially homeotropically in the background region, while aligning the liquid crystal molecules 5a and the dichromatic colorant 6a non-homeotropically in the display region.Also, convex faces 3 are formed for narrowing the distance in the background region.
However, according to this device, as shown in Figure 1 b, when a voltage is applied on the electrode 4 by actuation of the switch 7 to extinguish the color in the display region, the density in the display region will become higher in correspondence to the difference in thickness between the cell distances, because the liquid crystal molecules in both of the background region and the display region are basically vertically aligned, whereby a difference in coloration will be created between the background region and the display region. Besides, in the case of vertical orientation, mono-domain structure of liquid crystal does not readily develop in the display region and therefore color irregularity is liable to be formed.Furthermore, there is also involved a drawback that severe control of the cell distance is critical, because increase in the thickness of cell distance over a predetermined value will result in not the homeotropic alignment but the grandjean texture of the liquid crystal to cause coloration in the background region An object of the present invention is to provide an electrooptic device, particularly a guest-host type liquid crystal display device, free of the drawbacks as described above.
Another object of the present invention is to provide a guest-host type liquid crystal display device in which the coloration degree in the background region is made approximately the same as the coloration degree in the display region during color extinction.
Such objects of the present invention can be accomplished by an electrooptic device, particularly a guest-host type liquid crystal display device, having a display region and a background region and comprising:
a pair of electrode plates juxtaposed with a space therebetween; and
a liquid crystal layer disposed between the electrode plates and comprising a dichromatic colorant and a liquid crystal which takes a grandjean texture with a spiral pitch under no application of voltage, the thickness of the liquid crystal layer in the background region being smaller than the spiral pitch of the grandjean texture, and the surfaces of the electrode plates contacting the liquid crystal having been horizontally orientated.
Figure la and Figure 1b are sectional views for illustration of operation modes of the guest-host type liquid crystal display device of the prior art.
Figure 2a and Figure 2b are sectional views for illustration of operation modes of the guest-host type liquid crystal display device of the present invention.
An electrooptic device constituting a preferred example of the present invention, particularly a guest-host type liquid crystal display device, can be prepared according to the following method including the steps of:
(1) applying on an electrode plate having a patterned electrode film in a desired shape a 1% solution of silane coupling agent "KBM-403" in isopropyl alcohol (produced by Shin-etsu Silicone K.K.) according to spin coating at 3000 rpm for 10 sec. and then heating the coated product at 1 30 C for 15 min.;;
(2) applying on the resultant product a polyimide forming liquid (a polyamide acid which is a condensation product of pyromellitic acid dianhydride and 4,4'-diaminodiphenyl ether) according to spin coating at 3000 rpm for 10 sec., followed by heating at 300"C for 30 min., to form a polyimide film thereon;
(3) applying a photoresist resin on the polyimide resin, and also applying thereon a photomaskfor masking of predetermined portions, namely the electrode forming portion (in the case of negative-type photoresist) or the background region (in the case of positive-type photoresist) to closely contact the photoresist before applying UV-ray irradiation thereon;;
(4) developing (etching) the photoresist film at predetermined portions with a developer thereby to remove the photoresist resin at the portions where the electrodes have been formed, followed by rinsing;
(5) rubbing the electrode plate thus treated with a cloth or a velvet in the direction at an angle, for example 45 (diagonal line direction) (horizontal orientation treatement);
(6) applying an epoxy adhesive in a line width of about 0.2 mm to 1 mm on the peripheral portion of the electrode plate according to a coating method such as the screen printing method;
(7) superposing another electrode plate having a counter electrode also treated in the same manner on the electrode plate so that their rubbing directions will be in parallel and then curing the epoxy resin to seal the two electrode plates.During this operation, for setting the distance between the two plates at a predetermined distance as hereinafter described, it is desirable to place glass fiber or glass beads on either one of the plates or incorporate glass fiber or glass beads in the above-mentioned epoxy resin; and it is also desirable that the two electrode plates are so superposed that their rubbing directions are parallel but reverse with each other;
(8) injecting a liquid crystal between a pair of the electrode plates in a conventional manner and seal the inlet for injection.
The cell prepared according to the method as mentioned above can be driven by an application voltage of ordinarily a.c. of, for example, about 2 to 20 volt, preferably about 5 to 10 volt. In this cell, under no application of voltage, a pattern in, for example, blue color is clearly displayed, but under application of voltage, the same transmittance as the background can be exhibited in the display region.
By applying ordinarily a voltage on the display portion and turning off the voltage for information display, an apparently positive display can be given and an observer can recognize visually a clear display having changed from the colorless state.
According to other preferable examples of the present invention, in place of the polyimide film used in the step (2) as mentioned above, it is possible to use a coating film of a resin such as polyvinyl alcohol, polyamideimide, polyesterimide, poly-p-xylylene, polyester, polycarbonate, polystyrene, cellulose resin, melamine resin, urea resin or acrylic resin or a coating film of an inorganic compound such as silicon monooxide, silicon dioxide, aluminum oxide, silicon nitride, magnesium fluoride or titanium dioxide. In the case of a coating film of an inorganic compound, the horizontal orientation may be effected according to oblique vapor deposition, if desired. These insulating films may preferably be formed in a thickness generally of 100 to 1 ,a, particularly 500 to 2000 .
A photoresist resin to be used in the above manner may be selected from a large number of commercially available products. Specific examples thereof may include photosensitive polyimide, photosensitive polyamide, cyclized rubber type photoresist, phenol-novolac type photoresist or electron beam-sensitive photoresist (such as polymethyl methacrylate, and epoxidezed-1,4-polybutadiene) and others, which, however, are not limitative of the scope of the present invention.
The liquid crystal to be used in the guest-host type liquid crystal device of the present invention if a cholesteric-nematic phase transition type liquid crystal, more specifically one capable of forming a cholesteric phase of grandjean texture under no application of voltage and forming a nematic phase through disintegration of grandjean texture under application of voltage.
The liquid crystal composition to be used in the present invention is preferably such a composition that it gives 2 to 3 spiral turns of liquid crystal between a pair of electrodes adopted. More specifically, there may preferably be employed a composition comprising a mixture of a combination of 97 to 98 wt.% of a nematic liquid crystal having positive dielectric anisotropy and 2 to 3 wt.% of a cholesteric liquid crystal or a combination of 94 to 97 wt. h of a nematic liquid crystal having positive dielectric anisotropy and 3 to 6 wt.% of a chiral nematic liquid crystal with 1 to 3 parts by weight of a dichromatic colorant per 100 parts by weight of the total amount of the combined liquid crystals.
Nematic liquid crystals having positive dielectric anisotropy are disclosed in, for example, U.S. Patents 4, 130,502; 4,154,697; 4,181,625; 4,214,819; 4,229,315; and 4,285,829. These nematic crystals having positive dielectric anisotropy may be used in mixture of two or more kinds. As the cholesteric liquid crystal, those disclosed in, for example, U.S. Patents 3,600,060 and 3,578,844 may be employed. As the chiral nematic liquid crystal, those disclosed by D. Dolphin, "J. Cham. Phys., Vol. 58, p.413(1973)"; and G. Meier, E.
Sackmann and J.K. Grabmaier, "Application of Liquid Crystals" (SpringerVerlag, Berlin (1975)) can be used.
Specific examples of chiral nematic liquid crystals are set forth below.
Typical examples of the dichromatic colorant or dye useful in the device of the present invention are shown below:
The following compositions are set forth to illustrate preferable liquid crystal compositions.
(1) "ZLI 1694 (mixed nematic liquid crystal having positive dielectric anisotropy, produced by Merck, West Germany).... . . . .. 95wt. parts
Chiral nematic liquid crystal No. 5 as shown above .... 3wt. parts
Dichromatic dye No. 13 as shown above .... 2 wt. parts (2) "ZLI 1565" (mixed nematic liquid crystal having positive dielectric anisotropy, produced by Merck, West Germany) 96 wit. parts Chiral nematic liquid crystal No.3 as shown above ........................................ 4wt parts Dichromatic dye No. 13 as shown above 2 wt.2 wt. parts An example of the device according to the present invention is shown in Figures 2a and 2b.Figure 2a shows the state under non-actuation, and in between the plates 1 and 2 is sandwiched a liquid crystal 5, 5a (e.g. a chiral nematic liquid crystal, a cholesteric liquid crystal or a mixed crystal of these liquid crystals with a nematic liquid crystal), which is aligned in a spiral structure (grandjean texture) under application of no voltage, and a dichromatic dye 6, 6a. In the display region, there are arranged a pair of electrodes 4,4, which are covered with uniform insulating films 8. 8. In the non-display (or background) region, the distance is made smaller with the convex faces 3, 3 of a developed photoresist. Generally speaking, the thickness of the liquid crystal 5 may suitably be about 1 to 2 y, which is smaller than the spiral pitch.On the other hand, the thickness of the liquid crystal 5a in the display region may suitably be about 6to 10 Il. In Figure 2b, when the switch 7 is closed, the liquid crystal 5a in the display region is aligned along the electrical field direction and, as the result, its color is extinguished to have a coloration degree substantially the same as that in the non-display region.
According to the present invention, by making the cell interval at the background portion smaller than the spiral pitch of the liquid crystal molecules, the number of turns of liquid crystals can be suppressed even with application of the horizontal orientation treatment, thus resulting in an advantage that the background portion is not colored.
Moreover, since the horizontal orientation treatment by rubbing is applied, the change in density at the background portion occurs only proportionally even when the cell interval may change without accompanying density change as observed in the case of the change from the homeotropic alignment to the grandjean texture as in the conventional example, and there is also an advantage that some fluctuation in the cell interval can be tolerated.
Thus, in the display device of the present invention, as compared with a conventional display device of which electrode plates are vertically oriented over the whole face, although the background portion may be slightly colored, the display portion exhibits the same colored state as the background portion on color extinction of the display portion, whereby apparent contrast can be improved.
Claims (13)
1. An electrooptic device having a display region and a background region, comprising:
a pair of electrode plates juxtaposed with a space therebetween, and
a liquid crystal layer disposed between then electrode plates and comprising a dichromatic colorant and a liquid crystal which takes a grandjean texture with a spiral pitch under no application of voltage, the thickness of the liquid crystal layer in the background region being smaller than the spiral pitch of the grandjean texture, and the surfaces of the electrode plates contacting the liquid crystal having been subjected to horizontal orientation treatment.
2. An electrooptic device according to claim 1, wherein said liquid crystal has positive dielectric anisotropy.
3. An electrooptic device according to claim 1 or claim 2 wherein said liquid crystal is a mixed liquid crystal comprising a chiral nematic liquid crystal and a nematic liquid crystal.
4. An electrooptic device according to claim 1 or claim 2, wherein said liquid crystal is a mixed liquid crystal comprising cholesteric liquid crystal and a nematic liquid crystal.
5. An electrooptic device according to any preceding claim wherein the liquid crystal layer in the background region has a thickness of 1 to 2 X.
6. An electrooptic device according to any preceding claim wherein the liquid crystal layer sandwiched between a pair of electrodes has a thickness of 6 to 10 > .
7. An electrooptic device according to any preceding claim wherein insulating films are formed on said electrodes.
8. An electrooptic device according to any preceding claim, wherein said horizontal orientation treatment is conducted by rubbing.
9. An electrooptic device according to claim 8, wherein the directions of said rubbing on one electrode plate and the other electrode plate are parallel with each other.
10. An electrooptic device according to claim 9, wherein the directions of rubbing on the two electrode plates are parallel but opposite to each other.
11. An electrooptic device according to claim 1 including any one or more of compositions (1) to (7) or compounds 1 to 14 as hereinbefore specified.
12. An electrooptic device according to claim 1 including liquid crystal compositions (1) or (2) as hereinbefore specified.
13. An electrooptic device according to claim 1 substantially as hereinbefore described and illustrated.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19107782A JPS5979221A (en) | 1982-10-29 | 1982-10-29 | Electro-optical device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8328543D0 GB8328543D0 (en) | 1983-11-30 |
| GB2131194A true GB2131194A (en) | 1984-06-13 |
Family
ID=16268477
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08328543A Withdrawn GB2131194A (en) | 1982-10-29 | 1983-10-26 | Liquid crystal device |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPS5979221A (en) |
| DE (1) | DE3339275A1 (en) |
| GB (1) | GB2131194A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4725517A (en) * | 1984-08-10 | 1988-02-16 | Alpine Electronics Inc. | Method of manufacturing a liquid crystal display device |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6262334A (en) * | 1985-09-13 | 1987-03-19 | Canon Inc | Liquid crystal element |
| US5327273A (en) * | 1989-06-29 | 1994-07-05 | Hoffmann-La Roche Inc. | Bistable ferroelectric liquid crystal display cell |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2020053A (en) * | 1978-03-22 | 1979-11-07 | Ebauches Sa | Liquid crystal display |
-
1982
- 1982-10-29 JP JP19107782A patent/JPS5979221A/en active Pending
-
1983
- 1983-10-26 GB GB08328543A patent/GB2131194A/en not_active Withdrawn
- 1983-10-28 DE DE19833339275 patent/DE3339275A1/en not_active Withdrawn
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2020053A (en) * | 1978-03-22 | 1979-11-07 | Ebauches Sa | Liquid crystal display |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4725517A (en) * | 1984-08-10 | 1988-02-16 | Alpine Electronics Inc. | Method of manufacturing a liquid crystal display device |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8328543D0 (en) | 1983-11-30 |
| DE3339275A1 (en) | 1984-05-03 |
| JPS5979221A (en) | 1984-05-08 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |