This document is a technical seminar report submitted by Rohit Singh for the degree of Bachelor of Technology in Electronics and Telecommunication Engineering. It provides an introduction and overview of Ferroelectric Liquid Crystal Displays (FLCDs), including their operating principle, molecular orientation control, device structure, gray scale addressing, properties and uses. FLCDs utilize a chiral smectic C liquid crystal phase with spontaneous polarization, allowing bistable states that provide memory effect and fast response time.

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COLLEGE NAME
A
Technical seminar report
on
Ferroelectric liquid crystal display (FLCD)
In partial fulfillment for the award of the degree
Of
BACHELOR OF TECHNOLOGY
IN
ELECTRONICS & TELECOMMUNICATION ENGINEERING
SUBMITTED TO: SUBMITTED BY:
Assistant Professor

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CERTIFICATE
This is to certify that the technical seminar Report entitled “Ferroelectric
liquid crystal display” is a bonafied work presented by ROHIT SINGH in a
partial fulfillment for the award of degree of Bachelor of technology in
ELECTRONICS & TELECOMMUNICATION ENGINEERING in COLLEGE
OF ENGINEERING ROORKEE during the year 2011-2015.
Assistant Professor
College Of Engineering Roorkee

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Content
1. Introduction on Flcd…………………………………4
2. Lcd……………………………………………………5
2.1 Advantages and disadvantages on Lcd………8
3. Introduction of Amlcd………………………………10
4. Operation On Flcd………………………………….11
5. Molecular orientation control……………………..12
5.1 Key Technologies for the Vmin Mode FLCDs..14
5.2 Device Structure & Molecular Orientation…….15
5.3 Gray Scale and Addressing…………………….17
6. Properties and uses………………………………...19
7. Challenges…………………………………………..20
8. Conclusion…………………………………………..21
9. Refrences……………………………………………22

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Ferroelectric Liquid Crystal Display
Introduction
Ferro Liquid Display, or Ferro-electric Liquid Display (FLD) or Ferro Fluid Display
(FFD), is a display technology based on the ferroelectric properties of certain liquids.
Not all such fluids are crystal but they are generically referred to as Ferro Liquid
Crystal Displays (FLCD).
The dot pitch of such displays can be as low as 10 μm giving a very dense
high resolution display on a small area. These might find applications in 3D displays
and head mounted displays (HMD) where typical LCDs have failed to provide
anything better than a 640x480 (RGB pixel) resolution on a sq.cm display area.
Displays based on these are still experimental or of less commercial value only due
to the costs. Gradual adoption in consumer electronics is expected to bring the costs
down.
A major drawback is that the angle of twist is not easily controlled by intensity of
magnetic field. To produce color scales, time multiplexing might be used exploiting
the quick switching time. The materials found so far are sensitive to vibration and
shock.
Since Clark and Lagerwall invented the basic
principle of ferroelectric liquid crystal displays
(FLCDs), much effort has been devoted to
the development of FLCDs, aiming
at practical applications.
While the conventionally existing LCDs such as
STN LCDs and TFT-LCDs utilize a nematic liquid
crystal phase, it is remarked that FLCDs utilize a
chiral smectic C liquid crystal phase with
Fig. Principle of FLCD.

5. spontaneous polarization (Ps). In the chiral smectic C
phase, liquid crystal molecules have a layer
structure in which the mean direction of molecular long
axis is tilted against layers. In thin FLC cells, a bistability
appears with two bistable states as shown in Fig.1(a)(b) . Ferroelectric
liquid crystals have a spontaneous polarization (Ps) whose direction is
perpendicular to the layer. When the electric field is applied, molecules re-align in
a way that the direction of the spontaneous polarizations is the same as that of the
electric field. Combining a pair of polarizers (polarizer and analyzer), FLCDs can
realize dark and bright states.
Since nematic liquid crystal is paraelectric, the order of response time is usually
sec. On the contrary, FLC shows sec in its order of response time because of
the direct interaction between electric field and Ps. In addition, FLCDs have several
advantages, such as wide viewing angle due to the in-plane switching (IPS) and
memory effect due to the bistability. The combination of fast response time and
memory effect allows large-size direct-view simple-multiplexing LCDs with high
resolution.
LCD
LCD (liquid crystal display) (from Whatis) is the technology used for displays in
notebook and other smaller computers. Like light-emitting diode (LED) and gas-plasma
technologies, LCDs allow displays to be much thinner than cathode ray tube
(CRT) technology. LCDs consume much less power than LED and gas-display
displays because they work on the principle of blocking light rather than emitting it.
An LCD is made with either a passive matrix or an active matrix display display grid.
The active matrix LCD is also known as a thin film transistor (TFT) display. The
passive matrix LCD has a grid of conductors with pixels located at each intersection
in the grid. A current is sent across two conductors on the grid to control the light for
any pixel. An active matrix has a transistor located at each pixel intersection,
requiring less current to control the luminance of a pixel. For this reason, the current
in an active matrix display can be switched on and off more frequently, improving the
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6. screen refresh time (your mouse will appear to move more smoothly across the
screen, for example). Active matrix is the superior technology.
Color LCD
An LCD that can show colors must have three subpixels with red, green and blue
color filters to create each color pixel. Through the careful control and variation of the
voltage applied, the intensity of each subpixel can range over 256 shades.
Combining the subpixels produces a possible palette of 16.8 million colors (256
shades of red x 256 shades of green x 256 shades of blue), as shown below. These
color displays take an enormous number of transistors. For example, a typical laptop
computer supports resolutions up to 1,024x768. If we multiply 1,024 columns by 768
rows by 3 subpixels, we get 2,359,296 transistors etched onto the glass! If there is a
problem with any of these transistors, it creates a "bad pixel" on the display. Most
active matrix displays have a few bad pixels scattered across the screen.
LCD Features and Attributes
To evaluate the specifications of LCD monitors, here are a few more things you
need to know.
Native Resolution
Unlike CRT monitors, LCD monitors display information well at only the resolution
they are designed for, which is known as the native resolution. Digital displays
address each individual pixel using a fixed matrix of horizontal and vertical dots. If
you change the resolution settings, the LCD scales the image and the quality
suffers. Native resolutions are typically:
17 inch = 1024x768
19 inch = 1280x1024
20 inch = 1600x1200
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7. Viewing Angle
When you look at an LCD monitor from an angle, the image can look dimmer or
even disappear. Colors can also be misrepresented. To compensate for this
problem, LCD monitor makers have designed wider viewing angles. (Do not
confuse this with a widescreen display, which means the display is physically
wider.) Manufacturers give a measure of viewing angle in degrees (a greater
number of degrees is better). In general, look for between 120 and 170 degrees.
Because manufacturers measure viewing angles differently, the best way to
evaluate it is to test the display yourself. Check the angle from the top and bottom
as well as the sides, bearing in mind how you will typically use the display.
Brightness or Luminance
This is a measurement of the amount of light the LCD monitor produces. It is given
in nits or one candelas per square meter (cd/m2). One nit is equal to on cd/m2.
Typical brightness ratings range from 250 to 350 cd/m2 for monitors that perform
general-purpose tasks. For displaying movies, a brighter luminance rating such as
500 cd/m2 is desirable.
Contrast Ratio
The contrast ratio rates the degree of difference of an LCD monitor's ability to
produce bright whites and the dark blacks. The figure is usually expressed as a
ratio, for example, 500:1. Typically, contrast ratios range from 450:1 to 600:1, and
they can be rated as high as 1000:1. Ratios more than 600:1, however, provide
little improvement over lower ratios.
Response Rate
The response rate indicates how fast the monitor's pixels can change colors.
Faster is better because it reduces the ghosting effect when an image moves,
leaving a faint trial in such applications as videos or games.
Adjustability
Unlike CRT monitors, LCD monitors have much more flexibility for positioning the
screen the way you want it. LCD monitors can swivel, tilt up and down, and even
rotate from landscape (with the horizontal plane longer than the vertical plane) to
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8. portrait mode (with the vertical plane longer than the horizontal plane). In addition,
because they are lightweight and thin, most LCD monitors have built-in brackets for
wall or arm mounting. Besides the basic features, some LCD monitors have other
conveniences such as integrated speakers, built-in Universal Serial Bus (USB)
ports and anti-theft locks.
Advantages of Lcd
 Thin Profile
LCDs feature very thin profiles, making them the perfect choice for small
work spaces.
 Standard Screen Sizes
Unlike CRTs, there is no variance between the monitor size and the screen
size. For example, a 17-inch monitor features a 17-inch viewable image.
 Bright Screens
LCDs, thanks to the florescent backlight, produce bright, rich images
 Low Energy Consumption
In general, LCD monitors consume about half of the energy of standard
CRTs.
 Flicker-Free Refresh Rates
Refresh rate is less of an issue with LCD monitors. LCDs are designed to
have flicker-free refresh rates at 60Hz.
 High Contrast Ratios
LCD monitors tend to feature excellent contrast ratios, which insure bright,
clear images. Make sure the monitor you purchase has a contrast ratio of at
least 400:1 or more.
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9. Disadvantages of Lcd
 Single Resolution
LCDs are generally designed to work best in a single resolution. They tend
not to have the flexibility that CRTs have to display multiple resolutions well.
 Narrow Viewing Angles
LCDs tend to have a very narrow viewing angle. As you vary from looking at
a LCD straight-on the image gradually degrades. Look for at least a 160°
viewing angle.
 Slow Pixel Response Time
LCDs tend to have a much slower pixel response time, which can mean
image artifacts remaining onscreen after movement. For example, when you
move your mouse quickly across the screen you might see the cursor create
shadow images of itself briefly. These disappear instantaneously. In order to
avoid this try to find a monitor that has a response time of 25 milliseconds or
faster.
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10. Active Matrix Crystal Display
An active-matrix liquid-crystal display (AMLCD) is a type of flat panel display, the only
viable technology for high-resolution TVs, computer monitors, notebook
computers, tablet computers and smartphones with an LCD screen, due to low
weight, very good image quality, wide color gamut and response time.
The concept of active-matrix LCDs was invented by Bernard J. Lechner at the RCA
Laboratories in 1968.The first functional AMLCD display with thin-film transistors was
made byT Peter Brody and his team at Westinghouse Electric Corporation in
1973.]However, it took years of additional research by others to launch successful
products.
Introduction on Active Matrix Crystal Display
The most common type of LCD display contains, besides the polarizing sheets and
cells of liquid crystal, a matrix of thin-film transistors to make a thin-film-transistor
liquid-crystal display.These devices store the electrical state of each pixel on the
display while all the other pixels are being updated. This method provides a much
brighter, sharper display than a passive matrix of the same size. An important
specification for these displays is their viewing-angle.
Thin-film transistors are usually used for constructing an active matrix so that the two
terms are often interchanged, even though a thin-film transistor is just one
component in an active matrix and some active-matrix designs have used other
components such as diodes. Whereas a passive matrix display uses a simple
conductive grid to apply a voltage to the liquid crystals in the target area, an active-matrix
display uses a grid of transistors and capacitors with the ability to hold a
charge for a limited period of time. Because of the switching action of transistors, only
the desired pixel receives a charge, and the pixel acts as a capacitor to hold the
charge until the next refresh cycle, improving image quality over a passive matrix.
This is a special version of a sample-and-hold circuit.
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11. FLCD Operating Principle
An FLCD acts as a classical half-wave plate, one whose optic axis can be reoriented
by an applied field.
If the optic axis is parallel or perpendicular to incoming polarized light, the light
passes through the FLCD unchanged and is blocked by the exit polarizer(oriented at
90o to the entrance polarizer)
If the optic axis makes an angle of 45o to the incoming polarized light, the direction of
polarization changes by 90o and is able to pass through the exit polarizer
Orientation of FLF molecules is changed by applying a voltage pulse of suitable
polarity.
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12. • In thin FLC cells, a bistability appears with two bistable states as shown in Fig.
• Ferroelectric liquid crystals have a spontaneous polarization (Ps) whose
direction is perpendicular to the layer.
• When the electric field is applied, molecules re-align in a way that the direction
of the spontaneous polarizations is the same as that of the electric field.
• Combining a pair of polarizers (polarizer and analyzer), FLCDs can realize dark
and bright states.
Molecular orientation control
The molecular orientation control is one of the most important key
technologies for the development of practical FLCDs. The molecular orientations
of FLCDs are classified as two layer structures: a bookshelf layer and a chevron
layer. The FLC cells with parallel rubbing, in which the rubbing directions of both
substrates are the same, have been known to show four orientational states
with a chevron layer structure: C1-uniform (C1U), C1-twisted (C1T), C2- uniform
(C2U) and C2-twisted (C2T). Among them, the C1U and C2U orientations are useful
for practical applications because of their extinction positions between cross nicols.
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13. • So, an unconstrained system, the azimuthal
direction in which the molecules tilt away from
the layer normal will differ slightly from one
layer to the next.
• Typically, the FLCDs are built with cell gaps
less than 2 μm for stable molecular alignment.
• Alignment layer causes perpendicular stacked
alignment.
• The cell's polarisation is determined by the
magnetic field applied.
That in turn results in opaque or transparent layer
when used in combination with polarised layers as in
LCD
The alignment film with a high pre-tilt angle (over 15 degrees) induced the selective
formation of the C1U orientation and also that the C1U orientation gave a high
contrast ratio under simple-multiplexing driving waveforms for FLCDs. Using the
C1U orientation, Hanyu et al. have developed a 21-inch color FLCD (1024 x 1280
dots, contrast ratio of 40:1 and 64 colors).
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Fig. Principle of FLCD.

14. Recently, Mizutani et al. developed a 15" full-color FLCD (768 x 1024 dots,
36 sec/line, CR=100:1) with a bookshelf layer structure, realizing full-color images
by a combination of 4-bit spatial dither and dither methods.Futhermore, Koden et al.
have reported that the C2U orientation can show a high contrast ratio, fast line
address time and wide memory angle if it is combined with the -Vmin.
The -Vmin mode utilizes the unique response (t) - voltage (V) characteristics of the
minimum value, which is observed in FLC materials with large positive dielectric
biaxiality (negative dielectric anisotropy). The -Vmin mode utilizing the C2U
orientation is a promising technology for digital gray scale method with temporal
dither because it can realize faster line address time than the C1U orientation and
the bookshelf orientation can.
Compared with the existing LCDs, the FLCD have received an unfavorable
reputation of poor performance in moving picture with gray scale and also in
shock stability. In this study, key technologies for the -Vmin mode were
developed in order to overcome these problems. This paper describes FLC
materials that show fast response time for the -Vmin mode, the selective
formation of the C2U orientation, the device structure with high shock stability and
the digital gray scale driving method, introducing a6-inch color prototype FLCD
which was fabricated by using these keytechnologies.
1. Key Technologies for the -Vmin Mode FLCDs
1•1 Ferroelectric Liquid Crystal Materials
In the -Vmin characteristics of FLC materials, the minimum voltage ismentioned as
Vmin and the minimum response time as min. Low Vmin and fast min are
required because the Vmin value determines the drive voltage and the min value
determines the line address time. Since the Vmin is closely related to a balance of
the dielectric biaxiality and spontaneous polarization (Ps), FLC materials for the
-Vmin mode need large positive dielectric biaxiality and small or moderate
spontaneous polarization, as well as low viscosity in order to obtain fast tmin.
An INAC phase sequence and long
helical pitches in nematic and smectic
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15. C phases are required in order to
yield a high quality of alignment on
cooling from the isotropic phase.In
addition, FLC materials require wide
temperature range of smectic C phase
because it is related to the operating
and storage temperature ranges of
FLCDs.
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Fig. 2 The characteristic of the developed FLC material FDS-2.
A typical FLC material, FDS-2 was developed for the -Vmin mode. Its
characteristics are shown in Fig. 2. This material offers fast min value (12 sec)
and reasonable Vmin value (33V) at 25˚C.
1•2 Device Structure & Molecular Orientation
Shown in Fig. 3 is the structure of the developed FLCD. On a color filter substrate
and a glass substrate with ITO electrodes, there are an insulating film and an
aligning films coated. The material of the aligning film was polyimide. The rubbing
direction of both substrates is in the same direction (parallel rubbing). An aligning
film with a medium pretilt angle (about 3˚) was utilized in order to gain 100% of
the C2U state without any zigzag defects or any C1 states. The molecular
orientation model of the C2U state is illustrated in Fig. 4.
Each pixel is divided into two areas with 1:2 ratio so as to realize spatial dither
gray scale, as described in the next section. Spacer walls were constructed within
the panel in order to show high shock stability. The cell spacing was 1.3 m.
Optimal adhesion between both substrates was obtained, yielding higher shock
stability more than 20kg/cm2.

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Fig. 3 Device structure of
the developed FLCD.
Fig. 4 The C2U orientation.

17. 1•3 Gray Scale and Addressing
Combining 2-bit spatial dither and 3-bit temporal dither, 64 gray levels for each
color were achieved to realize 262,000 colors. The 2-bit spatial dither ratio was
one to two (1:2) and 3-bit temporal dither ratio was one to four to sixteen (1:4:16).
The driving waveforms are shown in Fig.5. The duty ratio was 1/480 and the line
address time was 23 sec/line. The typical values of voltages were Vs=40V and
Vd=7V.
Fig. 5 Drive waveform which is applied in the 6"-prototype FLCD.
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18. 2. 6-Inch Color FLCD (Prototype)
A color 6"-prototype FLCD with 240x320
dots was fabricated, utilizing key technologies
described in the above. The main
specifications are as follows:
Number of Pixels 240 x 320 dots
Number of Colors 262,000 colors
Contrast Ratio 60:1
Shock Stability 20kg/cm2
Memory Angle 30 degrees
More detailed specifications are summarized in
Table 1 Conclusion
The development described in this paper has
solved two fundamental problems of FLCD.
The one is gray scale and the other is shock
stability. Further development is required in
order to realize large size FLCDs with high
information content and also to solve the
pseudo edge problem,which is induced by
digital gray technique as well as PDP.
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Table 1 The specifications of the developed
6"color FL

19. Properties and uses
 Very thin layer (less than 2 μm thick) can help produce a 90° polarisation
twist.
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1) High density displays with small display areas can be produced.
2) DisplayTECH claims that a stamp sized FLCD can drive resolutions
needed for 50 inch screens.
 Switching time is less than 100 μs
1) High frame rate video displays are possible.
 Magnetic polarisation effect is bistable.
1) Can be used for low frame rate displays that can run on very low
power
2) This property can help build display with non-volatile memory with the
advantage that the memory can be changed easily.
 Viewing angle is greater than 120°
1) This makes it suitable for commercial TV applications.
 Some commercial products do seem to utilize FLCD.
 High switching allows building optical switches and shutters in printer heads.

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Challenges
• The problems facing ferroelectric researchers are numerous.
• Alignment defect control (sensitive to shock and vibration)
• Cell spacing control
• Temperature range
• Response time, and Gray Scale
New fluorinated liquid crystal compounds are being developed to
help decrease the response time and improve the contrast ratio
(contrast is limited by defects).

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Conclusion
• Prospects for the future are mixed for this technology.
• While much research continues, it is unclear what market the
ferroelectric LCD will serve.
• Certainly, if the problems can be solved, then the high contrast
and wide viewing angle achieved with ferroelectric LCDs will
put them in competition with active matrix LCDs.

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References
 N. A. Clark and S. T. Lagerwall, Appl. Phys. Lett., 36, 899 (1980).
 Mitsuhiro Koden, Optronics, No.2, 52 (1994).
 M. Koden, Ferroelectrics, 179, 121 (1996).
 M. Koden, H. Katsuse, A. Tagawa, K. Tamai, N. Itoh, S. Miyoshi and
T. Wada, Jpn. J. Appl.
 A. Tsuboyama, Y. Hanyu, S. Yoshihara and J. Kanbe, Proc. Japan
Display '92, 53 (1992).
 M. Koden, T. Numao, N. Itoh, M. Shiomi, S. Miyoshi and T. Wada,
roc. Japan Display '92,
 Y. Hanyu, K. Namamura, Y. Hotta, S. Yoshihara and J. Kanbe, SID
93 Digest, 364 (1993).
 H. Mizutani, A. Tsuboyama, Y. Hanyu, S. Okada, M. Terada and K.
Katagiri,

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