JPH1172772A - Plasma address liquid crystal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the proportion of an electric field applied on a liquid crystal layer of PALC(plasma address liquid crystal device) and to obtain fast switching response by constituting a surface mode liquid crystal device by the cooperation of a liquid crystal layer and first and second surfaces. SOLUTION: An orienting layer 12 comprising two layers is formed on a dielectric layer 3, and the orienting layer 12 gives a pretilt angle of about 80 deg.. Also an orienting layer 15 is formed in the same way on a stripe electrode 9. Substrates 2, 5 are disposed while keeping a space between the orienting layers 12, 15 by a glass spacer 16. The space between the orienting layers 12, 15 is filled with a nematic liquid crystal material to form a liquid crystal layer 1. Since the nematic liquid crystal layer 1 has negative dielectric anisotropy, it is easily oriented in such a manner that the minor axis of molecules is in the same direction as the electric field. The orienting layers 12, 15 show parallel orientation direction to each other. Thereby, liquid crystal molecules in the liquid crystal layer 1 form a curved arrangement state (bending state) which crosses the thickness direction of the liquid crystal layer 1 when no voltage is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma addressed liquid crystal device (PALC), and is used, for example, as a display.

[0002]

2. Description of the Related Art FIG. 1 shows a known type of PALC.
1 illustrates a device. This PALC device has a layer 1 made of a liquid crystal material disposed between a glass substrate 2 and a dielectric layer 3. The liquid crystal layer 1 is separated by a dielectric layer 3 from a periodic array of channels 4 filled with gas / plasma. The channel 4 is obtained by etching a glass substrate 5. The electrodes 6 and 7 acting as the cathode and the anode, respectively, extend along the channel 4. Cathode 6 is connected to ground and anode 7 is connected to row driver 8 of the strobe signal generator. The strobe signal generator is part of the address generator for refreshing one row of the device at a time.

The substrate 2 has a strip electrode 9 on the lower surface. The strip electrodes 9 comprise a transparent conductor such as tin-doped indium oxide, forming a periodic array of column electrodes. Column electrode 9
Are connected to a column driver 10 of the data signal generator, which is part of the address generator. The column electrodes 9 and the channels 4 extend perpendicular to each other and form a periodic array of pixels in the area of the liquid crystal layer 1 where they overlap when viewed from above.

In operation, a data signal generator supplies a data signal to a column electrode 9 via a driver 10 to refresh one row of pixels. The state of the gas in each channel 4 determines whether an electric field is generated that occurs in the corresponding row of pixels. When a data voltage is applied to the column electrode 9, the voltage actually generated in the pixel depends on the gas state. The state of the gas behaves as either a conductive plasma or a dielectric insulator.

[0005] When a sufficiently high voltage is applied to the anode 7, one of the channels 4, the gas in the channel is ionized and enters a conductive plasma state. A pixel data voltage is applied to the row of pixels, so that the row is refreshed with new pixel data. Channel 4 is in turn addressed or strobed in synchronization with the generation of the data voltage. Therefore, the displayed image can be refreshed one line at a time. When all rows have been refreshed, the process is repeated for the next field or frame of image data.

The disadvantages of this type of PALC device are:
It is necessary to provide a dielectric layer or barrier 3 between the liquid crystal layer 1 and the gas / plasma in the channel 4.
When an arbitrarily applied voltage is applied to the column electrode 9, a part of the voltage is “dropped” by the dielectric layer 3, so that only a part of the voltage is generated in the liquid crystal layer 1. The ratio between the voltages generated in the liquid crystal layer 1 and the dielectric layer 3 depends on the ratio between the dielectric constant and the thickness of these layers. _Assuming the thickness d _LC of the liquid crystal layer, the dielectric constant ε _LC , the thickness d _{barrier of} the dielectric layer, and the dielectric constant ε _{bar rier} , the ratio of the voltage generated between the liquid crystal layer and the dielectric layer is given by the following equation. (d _LC / d _barrier ) (ε _barrier / ε _LC ) = (V _LC / V _barrier ) As disclosed in WO96 / 19789, in order to maximize the ratio of the applied voltage generated in the liquid crystal layer 1, The layer thickness ratio (d _LC / d _barrier ) should be maximized. However, in practice, most liquid crystal devices used as large information capacity displays, such as computer screens and flat screen televisions, have a liquid crystal layer thickness limited to the order of 5 micrometers. Also, it is generally impractical to handle large area sheets of dielectric layer (usually glass) having a thickness much less than 50 micrometers in the manufacturing process.

Devices using a thick liquid crystal layer are usually
If the thickness of the liquid crystal layer 1 is increased, difficulties arise because the optical response is slow. For example, it is well known that the relaxation time in many liquid crystal devices is proportional to the square of the thickness of the liquid crystal layer.

[0008] A moving image is composed of continuous still images. To integrate still images into a continuously changing image,
Still images need to be updated or refreshed fast enough for the human eye. If individual images are updated too slowly, unwanted flicker will be visible. In order to eliminate visible flicker, the electro-optical switching time of the liquid crystal layer 1 should be as short as possible. For example, eliminating flicker requires updating the video image, typically at 60 Hz or faster, so that the liquid crystal layer responds in less than about 15 milliseconds.

Most commercially available active matrix driven large information capacity liquid crystal displays use the well-known twisted nematic mode. This mode tends to be limited to response times typically greater than 15 milliseconds in devices with a liquid crystal layer thickness of 5 micrometers.
Any attempt to increase the thickness of such displays further delays response time. Therefore, such displays are impractical for high information video rate displays.

[0010] Sov. J. Quant. Electro by Berezin et al.
n. Vol 3 (1), 1973, pp. 78-79, discloses the concept of surface mode liquid crystal devices. With this device,
All molecules, except for the thin layer in contact with the electrodes, are oriented in the same direction as the applied electric field.

US Pat. No. 4,653,051 discloses a surface liquid crystal device of the type known as a pi cell. This content is incorporated herein by reference. WO 97/12275 discloses a surface switching nematic liquid crystal device having negative dielectric anisotropy. This content is incorporated herein by reference. Matsumoto et al. Journal of Applied Phys
ics, Vol. 47, 1976, pages 3842-3845, which is incorporated herein by reference. This reference discloses a hybrid oriented nematic (HAN) device in which one surface of the nematic liquid crystal layer has a low pretilt and the other surface is homeotropic, ie, substantially 90 degrees pretilt.

[0012]

As described above, in the conventional PALC device, it is an issue to reduce the ratio of the given electric field to be dropped in the dielectric layer, that is, to increase the ratio given to the liquid crystal layer. there were. For that purpose, it is necessary to increase the thickness of the liquid crystal layer or to reduce the thickness of the dielectric layer. However, the thicker the liquid crystal layer, the slower the electro-optical response, and the thinner the dielectric layer,
Handling in the manufacturing process becomes difficult.

It is an object of the present invention to provide an electric field
An object of the present invention is to provide a PALC device that can be applied as a large information capacity display and can provide a higher ratio to a liquid crystal layer of the PALC device and realize a high-speed switching response.

[0014]

According to the present invention, a first substrate including a plasma-addressed configuration and a first surface, and a first substrate including a second surface spaced apart from the first surface. A plasma addressed liquid crystal comprising a second substrate and a liquid crystal layer disposed between the first and second surfaces, wherein the liquid crystal layer and the first and second surfaces cooperate to form a surface mode liquid crystal device A device can be provided, which achieves the above objectives.

As used herein, the term "surface mode liquid crystal device" refers to the fact that during switching between an on state and an off state, reorientation occurs in a region in the liquid crystal layer near one or both surfaces. A device whose dominant optical change is controlled.

[0016] The first surface may include a first alignment layer.

[0017] The second surface may include a second alignment layer.

The first and second alignment layers may have parallel alignment directions.

The liquid crystal layer may include a nematic liquid crystal material.

The nematic liquid crystal may have a negative dielectric anisotropy and be switchable between the first and second birefringence modes. In the first and second birefringence modes, liquid crystal molecules in an intermediate region of the liquid crystal layer may be in a spray state. The difference in optical retardation of these modes can be an odd multiple of 波長 wavelength for transmissive devices or an odd multiple of 波長 wavelength for reflective devices.

The first and second alignment layers can provide a pretilt substantially in the range of 80 to 90 degrees.

The nematic liquid crystal may have a positive dielectric anisotropy and be switchable between the first and second birefringence modes. In the first and second birefringence modes, liquid crystal molecules in an intermediate region of the liquid crystal layer may be in a homogeneous state. The difference in optical retardation of these modes can be an odd multiple of 波長 wavelength for transmissive devices or an odd multiple of 波長 wavelength for reflective devices.

The first and second alignment layers can provide a pretilt substantially greater than 1 degree.

The first and second alignment layers can provide a pretilt substantially less than 10 degrees.

The first and second alignment layers can provide a pretilt substantially less than 5 degrees.

The thickness of the liquid crystal layer can be substantially 6 micrometers or more.

The first substrate may include a plurality of gas-filled channels. The plurality of channels extend substantially parallel to each other and are separated from the liquid crystal layer by a dielectric layer.

[0028] The dielectric layer may include glass.

[0029] The thickness of the dielectric layer may be substantially 50 micrometers or more.

The second substrate may include a plurality of strip electrodes substantially perpendicular to the channel.

[0031] The device may include a stationary retarder having an optical axis substantially perpendicular to the optical axis of the liquid crystal layer.

[0032] The device may include first and second polarizers positioned face to face on the liquid crystal layer.

The polarization transmission directions of the first and second polarizers can be substantially parallel or substantially orthogonal.

The polarization direction can be 45 degrees with respect to the optical axis of the liquid crystal layer.

The device may have a polarizer and a reflector placed face-to-face with the liquid crystal layer.

The polarization transmission direction can be 45 degrees with respect to the optical axis of the liquid crystal layer.

The operation of the present invention will be described below.

It is possible to provide a device that can increase the ratio of the applied electric field to the liquid crystal layer of the PALC device and realize a high-speed switching response. While having a relatively fast switching time and maintaining the thickness of the dielectric layer between the liquid crystal layer and the gas-filled channel to a size that is convenient to handle in device fabrication,
The thickness of the liquid crystal layer can be increased. Well-known PAL
Manufacturing techniques for C devices can be used with little or no penalty in terms of cost and complexity. PALC devices that can operate at standard video rates and provide large information capacities can be easily manufactured.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The display of FIG. 2 comprises a layer 1 of a nematic liquid crystal material having a negative dielectric anisotropy. An example of a suitable material is ZL14788-000 (Merck, Darmst
adt, Germany). About 1-2 wt% for liquid crystal material
Of a photocurable diacrylate monomer such as RM257 (Merck). The photocurable diacrylate monomer can be polymerized while an electric field is applied to the liquid crystal layer 1. Once the photopolymerization has taken place, the electric field can be removed and the liquid crystal molecules will remain aligned as if a voltage was still occurring. However, because these liquid crystal molecules have sufficient mobility, they can be further realigned at higher voltages, forming the liquid crystal modes described below. Liquid crystal layer 1
Is Corning7059 (Corning, New York, USA)
And between the substrates 2 and 5 made of glass having a low sodium ion content.

On the substrate 5, the electrodes 6 and 7 are formed of any suitable conductive metal or other material, such as aluminum, chromium or titanium oxide. Ribs 11 are formed on the upper surfaces of electrodes 6 and 7 on substrate 5 and define channels. The channels are electrodes 6 and 7 such as helium.
During this time, an appropriate gas for forming a plasma when an appropriate voltage is applied is held. To improve the uniformity of the plasma discharge, the walls of the channel 4 may be coated with a thin dielectric layer of a so-called "frit", as disclosed in EP 0798738. The dielectric layer 3 seals the channel 4. The dielectric layer 3 comprises a thin layer of glass, for example, having a thickness of 50 micrometers.

The alignment layer 12 is formed on the dielectric layer 3. For example, the alignment layer can be formed from two layers by the following method.

A polyimide layer such as PI2555 (manufactured by DuPont) is spin-coated on the dielectric layer 3 and baked at 250 ° C. for 1 hour. The resulting layer is rubbed in one direction with a nylon cloth to form a pretilt alignment direction. 30% RM3 in organic reactive mesogen material RM257
The mixture added with 05 is dissolved in 15 times the weight of toluene. A small amount (eg, 1 wt%) of a photoinitiator (eg, Dara
cur4265, Ciba Specialty Chemicals, Basel, Switzerland) is added and the solution is spin-coated (10 kPa at 5 krpm) on the polyimide-coated dielectric layer 3.
Seconds). The RM layer was cured by ultraviolet irradiation in a nitrogen atmosphere to form an alignment layer 12. The alignment layer 12 forms a pretilt on the order of 80 degrees.

As indicated by reference numeral 13 on the substrate 2,
Form three color filters of red, green and blue. The filter may be made of an organic material such as gelatin polyimide and may be formed in a conventional manner. A light-impermeable region forming the black matrix 14 is also arranged on the substrate 2. Thereby, the rib 11 can be made invisible when viewing the device. Black matrix 14 may include a metal, such as chrome, and may be formed in a conventional manner.

A thin layer of tin-doped indium oxide (ITO) is deposited on the filter 13 and the matrix 14,
A strip electrode 9 is formed. For example, ITO can be deposited by sputtering under an argon atmosphere at a pressure of a few millitorr. Thereafter, it is selectively etched to obtain parallel strips extending perpendicular to the channel 4. A protective layer (not shown) of a material such as silicon nitride may be deposited between the strip electrode 9 and the filter 13 and matrix 14 by, for example, a chemical vapor deposition method.

The alignment layer 15 is formed on the strip electrode 9 in the same manner as the alignment layer 12, for example. Next, the alignment layers 12 and 1
5 are parallel and, for example, 6 micrometer glass or plastic beads (Dodwell Hi-tec
The substrates 2 and 5 are arranged so that the orientation layers 12 and 15 are spaced by a spacer 16 having the shape of Company h (Tokyo, Japan). A region between the alignment layers 12 and 15 is filled with a liquid crystal material to form a liquid crystal layer 1.

A fixed retarder 17 is formed on the outer surface of the substrate 2. For example, the fixed retarder 17 can provide a retardation of 72 nanometers, and a PMM
A (polymethyl methacrylate, Comar, Kembrich, UK). The retarder 17 is positioned such that the optical axis of the retarder 17 is substantially perpendicular to the alignment direction of the alignment layers 12 and 15 and (as a result) the alignment direction of the optical axis of the liquid crystal layer 1. Compensation film 18 is formed on the outer surface of retarder 17 to provide positive retardation. The optical axis of the film 18 is substantially perpendicular to the plane of the film 18. The use of the compensation film 18 can improve the viewing angle of the device.

The polarizer 19 is formed on the compensation film 18. The polarization axis of polarizer 19 is oriented at a 45 degree angle to the orientation direction of alignment layers 12 and 15. Polarizer or mirror 20 is formed on the outer surface of substrate 5. Element 2 when providing a transmissive device
0 is a polarizer whose polarization axis is parallel or perpendicular to the polarization axis of the polarizer 19. If a reflective device is provided, element 20 comprises a mirror, such as a layer of aluminum or silver.

FIGS. 3A to 3C show the liquid crystal mode of the device shown in FIG. For simplicity of illustration, only the liquid crystal layer 1 and the alignment layers 12 and 15 are shown.

Since the nematic liquid crystal layer 1 has a negative dielectric anisotropy, the molecules prefer an orientation such that the short axis is in the same direction as the electric field. This result and the first and second alignment layers 1
As a result, the liquid crystal molecules of the liquid crystal layer 1 form a curved alignment state (bend state) crossing the thickness of the liquid crystal layer 1 at zero voltage (FIG. 3).
(a)). Therefore, this is the lowest energy state compatible with the requirement that a high pretilt occur at the surface of the alignment layers 12,15. When the voltage and the resulting electric field are increased, the liquid crystal molecules in the intermediate region 1a of the liquid crystal layer 1 become
Reorient so that the short axis is in the same direction as the given electric field. As a result, a spray state as shown in FIG. 3B is formed. In the spray state at a low voltage, the molecules are oriented perpendicular to the direction of the applied electric field only in the central thin portion of the intermediate region 1a. In this state, the birefringence of the liquid crystal layer 1 is perpendicular to the cell, since the orientation of most of the molecules is dominant in the direction perpendicular to the alignment layers 12, 15 and (as a result) to the substrates 2, 5. Small for incident light.

Under a higher voltage, as shown in FIG. 3 (c), the number of molecules (in the intermediate region 1a) that are reoriented so that the short axis is in the same direction as the electric field direction increases. Tier 1
Has an increased birefringence. By varying the applied voltage between a relatively low voltage (eg, 2V) and a relatively high voltage (eg, 6V), the birefringence of the liquid crystal layer 1 can be adjusted between a relatively low value and a relatively high value, respectively. Becomes Fixed retarder 1
7 is subtracted from the retardation of the liquid crystal layer 1. The retardation of the fixed retarder 17 is selected so that the retardation becomes zero at a predetermined low drive voltage. In the case of the transmission type, the net retardation obtained by combining the liquid crystal layer 1 and the retarder 17 is １ ／ at a high driving voltage
Wavelength. In general, the retardation in the spray state needs to change by an odd multiple of a half wavelength between a high drive voltage and a low drive voltage. Also, an intermediate drive voltage has the potential to provide halftones.

FIG. 4 illustrates various axes in one embodiment of the transmission device. The polarization direction or the transmission direction of the polarizer 20 is shown at 21, which is the reference direction for the other axes shown in FIG. The orientation directions of the alignment layers 12 and 15 and (as a result) the direction of the optical axis 22 of the liquid crystal layer 1 are −4.
5 degrees. On the other hand, the optical axis 2 of the fixed retarder 17
The direction of 3 is +45 degrees. The optical axis 24 of the compensation film 18 is oriented perpendicular to the film 18. Polarizer 1
The direction of the 9 polarization axes 25 is 90 degrees. When an electric field is applied to the pixels of the device such that the overall retardation is zero, the pixels behave substantially like an "orthogonal" polarizer, leaving a substantially opaque or less transparent state. Become. When the retardation of the fixed retarder 17 is subtracted from the retardation of the liquid crystal layer 1 to be equal to 波長 wavelength, the linearly polarized light from the polarizer 20 has a polarization direction rotated by 90 degrees and transmits through the polarizer 19. As a result, the pixel is in a transmissive state. Intermediate applied voltages are used to provide intermediate retardation, which in turn provides intermediate transmission or attenuation steps. Therefore, the halftone can be driven between a maximum transmission (white) state and a maximum non-transmission (black) state.

As described above, the polarization axis 25 of the polarizer 19 is
May be parallel to the polarimetric axis 21 of the polarizer 20. Also, element 20 may include a mirror to provide a reflective device. In this case, the retardation of the liquid crystal layer 1 is 波長 wavelength (or 1) at a high driving voltage and a low driving voltage.
(Odd number times ／ wavelength).

FIG. 5 shows a device different from FIG. 2 in that it is a pi cell type. The configuration of the director in operation is illustrated in 1d. Alignment layers 12 and 15 in FIG.
2 is different from the alignment layer in FIG. 2 in that it is arranged to give a low pretilt on the order of 1 to 5 degrees. These alignment layers can be made from polyimide-type materials such as Liralign AM-4200 (Merck, Darmstadt, Germany). For example, a 2% solution of the prepolymer in a solvent, such as N-methylpyrrolidione (N-methylpyrrolidione, Aldrich, Dorset, UK), is spin coated (5 krpm for 40 seconds) on the underlayer. This is baked at 180 ° C. for 1.5 hours to cause imidization or crosslinking of the prepolymer. Upon cooling, the alignment layer is rubbed in one direction with a soft cloth such as cotton to give the liquid crystal material a pretilted alignment layer.

The liquid crystal layer 1 is of the positive dielectric anisotropy nematic type and may comprise, for example, the material known as E7 from Merck (Darmstadt, Germany). The detailed operation of the pi-cell mode is described in U.S. Pat.
It is not described further here. Basically, when the voltage applied to the liquid crystal layer 1 (and the resulting electric field) is at a low driving voltage and at a high driving voltage, the retardation of the liquid crystal layer 1 is 1/1 in the case of a transmissive device. It changes by two wavelengths, or one quarter wavelength in the case of a reflective device. As a result, the optical operation is as described above. When the applied voltage is switched from a low drive voltage to a high drive voltage, the optical switching time of the liquid crystal layer 1 is on the order of 0.5 millisecond. On the other hand, the relaxation time corresponding to switching from a high drive voltage to a low drive voltage is on the order of 3 milliseconds.

The thickness of the liquid crystal layer 1 is generally substantially 6 micrometers or more. For example, the thickness can be 6.2 micrometers. MLC6000-100 and ZLI2293 (both
Other nematic liquid crystal materials may be used, such as Merck, Darmstadt, Germany). The retardation of the fixed retarder 17 can be selected to provide a convenient drive voltage range for the device.

[0056]

According to the present invention, it is possible to provide a device which can increase a ratio of a given electric field to a liquid crystal layer of a PALC device and realize a high-speed switching response. Therefore, an easy-to-manufacture P can operate at standard video rates and provide large information capacity.
An ALC device can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of each part of a known type of PALC display.

FIG. 2 is a cross-sectional view showing a part of a PALC display which is a component of one embodiment of the present invention.

3A to 3C are cross-sectional views illustrating a liquid crystal operation mode of the display of FIG. 2;

4 shows the relative directions of various axes in the display of FIG. 2;

FIG. 5: PALC component of another embodiment of the present invention.
FIG. 3 is a cross-sectional view showing a part of the display.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal layer 1a-1d Region in liquid crystal layer 2 Substrate 3 Dielectric layer 4 Gas filling channel 5 Substrate 6 Electrode 7 Electrode 8 Row driver 9 Strip electrode 10 Column driver 11 Rib 12 Alignment layer 13 Color filter 14 Black matrix 15 Alignment layer DESCRIPTION OF SYMBOLS 16 Spacer 17 Fixed retarder 18 Compensation film 19 Polarizer 20 Polarizer or mirror 21 Polarization axis 22 Optical axis of liquid crystal layer 23 Optical axis of fixed retarder 24 Optical axis of compensation film 25 Polarization axis

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Michael John Tauler, Inventor Ox2 9 UK Elix Oxford, Botley, The Garth 20 (72) Inventor Harry Garth Walton, UK Ox4 3NE Oxford, Cowley, View Champ Lane, View Champ Place 45

Claims (23)

[Claims] A first substrate including a plasma-addressable configuration and a first surface; a second substrate including a second surface spaced apart from the first surface; A plasma addressed liquid crystal device, comprising: a liquid crystal layer disposed between a second surface, wherein the liquid crystal layer and the first and second surfaces cooperate to form a surface mode liquid crystal device. 2. The method according to claim 1, wherein the first surface includes a first alignment layer.
The device of claim 1. 3. The method according to claim 2, wherein the second surface includes a second alignment layer.
The device according to claim 1. 4. The method according to claim 1, wherein the second surface includes a second alignment layer,
3. The device of claim 2, wherein the first and second alignment layers have parallel alignment directions. 5. The device according to claim 1, wherein said liquid crystal layer comprises a nematic liquid crystal material. 6. The liquid crystal layer includes a nematic liquid crystal material, wherein the nematic liquid crystal has a negative dielectric anisotropy, and is switchable between first and second birefringent modes, In the first and second birefringence modes, liquid crystal molecules in the intermediate region of the liquid crystal layer are in a spray state, and the difference in optical retardation between the first and second birefringence modes is １ ／ in the case of a transmission type device. 5. The device of claim 4, wherein the device is an odd multiple of a wavelength, or in the case of a reflective device, an odd multiple of a quarter wavelength. 7. The device of claim 6, wherein said first and second alignment layers provide a pretilt substantially in the range of 80 to 90 degrees. 8. The liquid crystal layer is a nematic liquid crystal material, the nematic liquid crystal has a positive dielectric anisotropy, and is switchable between a first and a second birefringence mode,
In the first and second birefringent modes, the liquid crystal molecules in the intermediate region of the liquid crystal layer are in a homogeneous state, and the difference in optical retardation between the first and second birefringent modes is different in the case of a transmission device. 5. The device of claim 4, wherein the device is an odd multiple of 1/2 wavelength, or in the case of a reflective device, an odd multiple of 1/4 wavelength. 9. The device of claim 8, wherein the first and second alignment layers provide a pretilt substantially greater than 1 degree. 10. The device of claim 9, wherein said first and second alignment layers provide a pretilt substantially less than 10 degrees. 11. The device of claim 10, wherein said first and second alignment layers provide a pretilt substantially less than 5 degrees. 12. The device according to claim 1, wherein the liquid crystal layer has a thickness of substantially 6 micrometers or more. 13. The method of claim 1, wherein the first substrate includes a plurality of gas-filled channels, the plurality of channels extending substantially parallel to one another, and separated from the liquid crystal layer by a dielectric layer. A device as described in Crab. 14. The device of claim 13, wherein said dielectric layer comprises glass. 15. The device according to claim 13, wherein the dielectric layer has a thickness of substantially 50 micrometers or more. 16. The apparatus of claim 13, wherein the second substrate includes a plurality of strip electrodes extending substantially perpendicular to the channel.
A device according to any of claims 1 to 15. 17. A fixed retarder having an optical axis substantially perpendicular to the optical axis of the liquid crystal layer.
7. The device according to any one of 6. 18. The method according to claim 1, further comprising a first polarizer and a second polarizer disposed on both sides of the liquid crystal layer.
18. The device according to any of claims 17 to 17. 19. The device according to claim 18, wherein the polarization transmission directions of the first and second polarizers are substantially parallel. 20. The device of claim 18, wherein the polarization transmission directions of the first and second polarizers are substantially orthogonal. 21. The device according to claim 19, wherein the polarization direction is 45 degrees with respect to an optical axis of the liquid crystal layer. 22. The device according to claim 1, comprising a polarizer and a reflector disposed on both sides of the liquid crystal layer. 23. The device according to claim 22, wherein the polarization transmission direction of the polarizer is 45 degrees with respect to the optical axis of the liquid crystal layer.