The History of Liquid-Crystal Displays
`
`HIROHISA KAWAMOTO, FELLOW, IEEE
`
`Invited Paper
`
`The modern history of liquid crystals has been dominated by
`the development of electronic displays. These developments began
`in 1964, when Heilmeier of RCA Laboratories discovered the
`guest-host mode and the dynamic-scattering mode. He thought
`a wall-sized flat-panel color TV was just around the corner.
`From that point on, twisted-nematic (TN) mode, super TN mode,
`amorphous-Si field-effect transistor, and room-temperature liquid
`crystals were developed. In the beginning, liquid-crystal displays
`(LCDs) were limited to niche applications such as small-size dis-
`plays for digital watches, pocket calculators, and small handheld
`devices. That all changed with the development of the notebook
`computer industry. In 1988, Washizuka et al. of Sharp Corporation
`demonstrated an active-matrix full-color full-motion 14-in display
`using a thin-film-transistor array. The electronics industries now
`recognized that Heilmeier’s 25-year dream of a wall-hanging tele-
`vision had become reality. LCDs could be used to replace existing
`cathode ray tubes. Through the cooperation and competition of
`many electronics giants, the LCD industry was firmly established.
`
`Keywords—Active matrix, amorphous silicon, azoxy, bire-
`fringence,
`cholesteric,
`cyanobiphenyl, dielectric anisotropy,
`digital watch, DSM, DSTN, ester, Fergason, Gray, guest host,
`Heilmeier, Helfrich, history, LCD, liquid crystals, MBBA, Nehring,
`nematic, PCH, pocket calculator, poly silicon, Raynes, rubbing,
`Schadt, Scheffer, Seiko, Sharp, STN, TFT, TN mode, transmission
`minimum, Wada, wall-hanging television, Washizuka, Williams
`domain, Yamazaki.
`
`I. INTRODUCTION
`
`The development of liquid-crystal displays (LCD) pro-
`ceeded from early successes like the pocket calculator to
`the major milestone of a flat-panel television display you
`can hang on a wall. The history of that development spans
`the world’s major industrial centers: the U.S., Japan, and
`Europe. I was fortunate to be a part of that history. When
`I joined RCA Laboratories at the David Sarnoff Research
`Center in April 1970, RCA was curtailing its efforts in
`liquid-crystal activities, but I had the opportunity to witness
`the developments there before the program’s group head,
`George Heilmeier, left for Capitol Hill as a White House
`
`Manuscript received October 20, 2000; revised August 3, 2001.
`The author is with Silicon Image Inc., Nara Gakuen-Mae, Japan (e-mail:
`kawamoto@zc4.so-net.ne.jp).
`Publisher Item Identifier S 0018-9219(02)03951-8.
`
`Fellow. Then, in 1985, I joined the Sharp Corporation in
`Japan and met Tomio Wada, the man who developed the
`world’s first liquid-crystal product, a pocket calculator, in
`1973. At Sharp, I also witnessed major development efforts
`in LCDs at the Tenri Advanced Development Center. In
`1990, I participated in the founding of the European Labo-
`ratories at Oxford, U.K., and in 1992, we welcomed Peter
`Raynes, known for his contributions to the applications of
`cyanobiphenyls, to the Laboratories. Through discussions
`with him, I learned about the achievements of British and
`European scientists.
`The modern history of liquid crystals is predominantly the
`history of the development of electronic displays made of
`liquid crystals. The developments started when a dynamic-
`scattering mode (DSM) was discovered in 1964. Manufac-
`turers of LCDs had been minor-league members of the elec-
`tronic display industry and served a niche market, supplying
`small-size displays primarily to pocket calculators and dig-
`ital watches. A major milestone was reached in 1988 when
`a 14-in active-matrix (AM) thin-film-transistor (TFT) dis-
`play was demonstrated. The electronics industries then rec-
`ognized that the dream of a wall-hanging television had be-
`come a reality, thus, promoting LCD manufacturers to the
`“major leagues” in the electronics industry. By 2000, the
`LCD industry had caught up to the giant cathode ray tube
`(CRT) industry. In this paper, I focus on the 25 years of
`LCD developments that gave birth to the present-day LCD
`industry. In writing this paper, I interviewed 37 scientists and
`engineers scattered throughout the world. Each section of the
`article concentrates on a key technical item that led to the ul-
`timate goal—the flat-panel television.
`What had been an obscure general and scientific curiosity
`for 80 years suddenly became the center of attention as the
`result of a new invention, spawning a new industry projected
`to reach 40 billion dollars by the year 2006. The history
`of LCDs is a story of the hard work, disappointments, and
`successes of worldwide competition and cooperation that
`encompassed the U.S., Europe, and Japan. Each industrial
`center contributed its particular strengths: in America, it
`was the quickness of forming new ideas and demonstrating
`their feasibility; in Europe, it was the fundamental science
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`and synthesis of basic materials; and in Japan, it was the
`process of perfecting implementation and moving it to the
`production line.
`
`II. DISCOVERY OF LIQUID CRYSTALS AND THEIR
`FUNDAMENTALS—THE NAME “LIQUID CRYSTALS” WAS
`BORN IN GERMANY
`
`As a material’s temperature is raised, it generally changes
`state from solid to liquid to gaseous. It is generally be-
`lieved that an Austrian botanist, Friedrich Reinitzer [see,
`e.g., Fig. 1(a)], first observed liquid crystals in 1888. He
`discovered a strange material that exhibited a mesophase
`between solid state and liquid state [1]. At a temperature
`of 145 C, it melted, becoming cloudy white and viscous.
`At a temperature of 179 C, it became isotropic and clear.
`The material he discovered was cholesteryl benzoate. On
`March 14, 1889, he wrote a letter to Otto Lehmann [see, e.g.,
`Fig. 1(b)], Professor of Physics at the Technical University
`Karlsruhe of Germany, telling him about the two melting
`points. Lehmann studied the material and discovered that the
`liquid at the mesophase exhibited a double refraction effect,
`characteristic of a crystal. Because it shared characteristics
`of both liquid and crystal, he named it “fliessende krystalle”
`and the name “liquid crystal” was born [2].
`Liquid crystals were not popular among scientists in the
`early 20th century and the material remained a scientific cu-
`riosity for 80 years. It should be noted that E. Merck of Darm-
`stadt, Germany, sold liquid crystals for analytical purposes
`as far back as 1907 (see Fig. 2). In the early 1960s, only a
`few institutions and corporations were known to have been
`carrying out research on liquid crystals. The prerequisites
`for designing liquid crystals with specific physical properties
`hardly existed, not to mention the lack of motivation to use
`it in a commercial product. Liquid crystals were unknown to
`the man on the street.
`
`A. Thermotropic and Lyotropic Liquid Crystals
`The liquid crystals Reinitzer discovered by varying their
`temperatures are called thermotropic liquid crystals (see
`Fig. 3). As the temperature is raised, their state changes
`from crystal to liquid crystal at temperature
`. Raising the
`temperature further changes the state from liquid crystal to
`isotropic fluid at temperature
`. Generally speaking, the
`process is reversible by lowering the temperature, though
`there may be a small temperature hysteresis; the
`value
`when reducing temperature may be slightly less than the
`value when increasing temperature. The
`is sometimes
`referred to as the “freezing” temperature and
`as the
`“clearing” temperature. For the case where a liquid crystal
`is of nematic type as will be discussed later, the
`is
`designated by
`and
`by
`.
`Another liquid crystal exists. It is called the lyotropic
`liquid crystal. This exhibits liquid-crystal behavior when
`it reacts with water or a specific solvent [4]. For example,
`the wall of a biological cell is made of lyotropic liquid
`crystals. Many biological structures such as the brain, nerve
`system, muscle, and blood contain lyotropic liquid crystals.
`
`(a)
`
`(b)
`
`Fig. 1. Scientists who discovered liquid crystals. (a) Friedrich
`Reinitzer (1857–1927). (b) Otto Lehmann (1855–1922). (Historical
`Exhibition, the 12th International Liquid Crystal Conference,
`Freiberg, Germany, August 15–19 , 1988).
`
`The lyotropic liquid crystals are primarily investigated in
`the fields of biochemistry, biophysics, and bionics. We will
`leave the discussion of lyotropic liquid crystals to other
`publications while we focus on thermotropic liquid crystals.
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`(a)
`
`(b)
`
`Fig. 4.
`
`(a) Cigar-like and (b) disc-like molecules [3].
`
`Fig. 2. Liquid crystals sold as far back as 1907 for analytical
`works in research laboratories. Courtesy of Ludwig Pohl.
`
`(a)
`
`(b)
`
`Fig. 3. Thermotropic liquid crystal [3].
`
`B. Cigar-Like and Disc-Like Molecules
`There are two types thermotropic liquid crystals. One
`type has cigar-like molecules, while the other has disc-like
`molecules and is referred to as “discotic” (see Fig. 4). Both
`types are mostly organic, as seen from the formulae of
`the examples given. The liquid crystals used in electronic
`displays are primarily of the cigar type. In this article,
`therefore, we concentrate on thermotropic liquid crystals
`made of cigar-like molecules. Only in the late 1990s did the
`discotic molecules find an application in electronic displays.
`They are used to make a sheet of film that expands the
`viewing angle of a twisted-nematic (TN) display.
`
`Fig. 5. Molecular alignments in liquid and liquid crystals. (a)
`Liquid. (b) Smectic. (c) Nematic.
`
`4(c)
`
`C. Thermotropic Liquid-Crystal Types
`There are three types of thermotropic liquid crystals.
`These are based on a system proposed by G. Friedel in 1922
`[5]. They are smectic, nematic, and cholesteric types.
`1) Smectic Liquid Crystals: Smectic comes from a Greek
`word meaning grease or clay. In smectic type liquid crystals,
`the cigar-like molecules are arranged side by side in a series
`of layers as shown in Fig. 5(b). The long axes of all molecules
`in a given layer are parallel to one another and perpendicular
`to the plane of layers. The layers are free to slip and move
`over each other. The smectic state is viscous, but fluid and
`ordered.
`2) Nematic Liquid Crystals: Nematic comes from a
`Greek word meaning thread-like. Under a microscope using
`polarized light, nematic liquid crystals appear as thread-like
`structures. In the nematic state, the molecules are not as
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`Fig. 6. Three molecular alignments of nematic liquid crystals [4]. (a) Splay. (b) Twist. (c) Bend.
`
`(a)
`
`(b)
`
`(c)
`
`highly ordered as in the smectic state, but they maintain their
`parallel order [see, e.g., Fig. 5(c)]. On average, the nematic
`liquid crystals are aligned in one direction. The direction is
`represented by a vector
`called a director. Liquid crystals
`used in electronic displays are primarily of the nematic type.
`Because of its specific molecular alignment, nematic
`liquid crystals exhibit anisotropic physical characteristics;
`their refractive index, dielectric constant, permeability, elec-
`trical conductivity, and viscosity measured in the direction
`of the long axis are different from those measured in the
`plane normal to the long axis. In nematic liquid crystals,
`the refractive index along the director axis is almost always
`larger than along the perpendicular axes. The electrical
`conductivity along the director axis is generally larger than
`along the perpendicular axes. The permeability is generally
`negative and its absolute value along the director axis is
`smaller than along the perpendicular axes.
`3) Cholesteric Liquid Crystals: These materials are dis-
`cussed later in this section.
`
`D. Elasticity
`liquid crystals deform their
`Under mechanical stress,
`molecular alignment. The deformation of nematic liquid
`crystals can be considered for three cases, shown in Fig. 6.
`The first is a “splay,” where molecules are spread by external
`stress, the second is a “twist” where molecules are twisted by
`an external stress, and the third is a “bend” where molecules
`are bent by an external stress. The relationship between the
`deformation and stress is expressed respectively by splay
`elasticity
`, twist elasticity
`, and bend elasticity
`.
`The elasticity of liquid crystals is of the order of 10
`to
`10
`dyne and is much lower than that of ordinary elastic
`material. This makes alignment modification of liquid crys-
`tals by the application of electrical field, magnetic field and
`external stress much easier. The density of free elastic energy
`for nematic liquid crystals under deformation is expressed by
`[4]
`
`div
`
`rot
`
`rot
`
`(1)
`
`KAWAMOTO: THE HISTORY OF LIQUID-CRYSTAL DISPLAYS
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`E. Dielectric Anisotropy
`Regarding the dielectric constant, there are two types
`of nematic liquid crystals. One is called positive dielectric
`anisotropy (p-type) and its dielectric constant along the
`director axis is larger than that along the axes perpen-
`dicular to the director [4]. The
`, which is equal to
`–
`, is in the range of
`10 to
`20. The
`other type is called negative dielectric anisotropy (n-type)
`and its dielectric constant along the director axis is smaller
`than that along the axes perpendicular to the director. The
`is in the range of
`1 to
`2.
`Applying an electrical field
`appears an electrical energy
`
`to the liquid crystals, there
`, where
`
`(2)
`Here, the first term is independent of the director
`. The
`second term changes value depending on the direction of
`.
`When
`is positive (p-type liquid crystal), the application
`of an electrical field greater than some certain critical value
`(
`) aligns the long axis of the molecules parallel to the
`direction of the electrical field
`. This happens because the
`electrical energy
`is minimized when the director
`is par-
`allel with the electrical field
`. On the other hand, when
`is negative (n-type liquid crystals), the long axis of molecules
`aligns perpendicular to the electrical field because the elec-
`trical energy is minimized when
`is at a right angle to
`.
`Therefore, by applying an electrical field, we can control the
`direction of nematic molecules.
`Consider the case when the alignment of molecules is such
`that the liquid crystals have been in their lowest energy state
`and an electrical field is then applied. The total free energy
`of the liquid crystal is expressed by the summation of elec-
`trical energy
`and elastic energy
`
`Integration
`
`(3)
`
`An important case in applications occurs when nematic
`liquid crystals are sandwiched by two parallel plates and the
`electrical field is applied normally to the plates. A critical
`field
`that causes the transition of the molecular alignment
`can be expressed by
`
`(4)
`
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`

`
`where d is the spacing ofthe plates. When the base state ofthe
`molecular alignment is homogeneous, kg; = k; 1 and when
`tl1e alignment is twisted, kn = lcu + (ls'33 — 2k-33)/-'1. When
`tl1e liquid crystals are positive and the alignment is twisted
`as shown in Fig. 6(b), the threshold voltage for transition is
`1/2
`
`A1
`k” + kn} -21:2-
`
`|A€€n|
`
`VC. : 7r
`
`E Birefiingence
`
`
`
`(5)
`
`Because of its double refraction or birefiingence property,
`a liquid crystal exhibits the following optical characteristics
`[4]-
`
`I) It redirects the direction of incoming light along the
`long axis (director 11.) of the liquid crystal.
`2) It changes the state ofpolarization (from linear, ellipse,
`or circular polarization to one of linear, ellipse and
`circular polarizations) and/or changes the direction of
`polarization.
`Liquid crystals are not as rigid as solids and are easily re-
`oriented, realigned, or deformed by applying electrical fields,
`magnetic fields, heat, and/or mechanical stresses. Accord-
`ingly, the optical characteristics based on the birefringence
`are easily affected. These make nematic liquid crystals at-
`tractive for use in electronic devices. The following sections
`trace the history of how scientists and engineers used such
`characteristics of nematic liquid crystals to construct elec-
`tronic displays.
`
`G. Cholesteric Liquid Crystals
`The term cholesteric is used because the molecular
`
`structure of the liquid crystals characteristically has a large
`number of compounds containing cholesterol
`[6]. The
`molecules in cholesteric liquid crystals are arranged in
`layers (see Fig. 7). Within each layer, molecules are aligned
`in parallel, similar to those in nematic liq11id crystals. The
`molecular layers in a cholesteric liquid crystal are very thin,
`with the long axes of the molecules parallel to the plane of
`the layers. A special aspect of the cholesteric structure is
`that the director 12. in each layer is displaced slightly from the
`corresponding director of the adjacent layer. The displace-
`ment is cumulative through successive layers, so that the
`overall displacement traces out a helical path. Because ofthe
`helical structure, it exhibits such interesting phenomena as
`optical rotation, selective reflection and two-color circular
`polarization.
`The phomenon of selective reflection was used in com-
`mercial applications before liquid crystals were used in dis-
`play applications. The pitch 1) of the helical structure is of
`the order ofthe wavelengths ofvisible light. A beam ofwhite
`light coming in the direction ofthe helical axis splits into two
`polarized beams: one beam with a right circular polarization
`and the other with a left circular polarization. Here, the light
`having its rotation ofpolarization in the same direction as the
`helical rotation is selectively reflected at the end surface; the
`light with the other rotation ofpolarization, transmits. Using
`the Bragg relation, we see that a film of the liquid crystal will
`
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`Hall Pitch
`
`Halt Pitch
`
`AW“
`E
`
`Fig. 7. Cholesteric liquid crystal [3].
`
`reflect the light and appear colored. The wavelength A of the
`reflected light is
`(nfwarallel + "‘12>(-x'1weI1dic1|lax')l1/2
`’\ : l)
`where -n,,a,.an(.1 and 72l,,.,.l,..,..ucu1a,. are refractive indices in
`parallel and rectangular respectively to the long axis of the
`molecule [4]. The pitch 1; is subject to change with temper-
`ature and so the color of the film also changes with temper-
`ature. Generally speaking, as temperature increases. 1) be-
`comes small and the reflected light moves to a shorter wave-
`length. Fergason and his group at Westinghouse Research
`Laboratories fabricated flexible films and tapes that can be
`applied to the surface ofobjects to record temperatures. They
`applied the film to the skin of a human body to locate veins
`and arteries and to electronic circuit boards to locate trouble
`
`spots [6]-
`incorporating cholesteric liquid crystals
`One product
`available in the market place is a stress testing card. This
`is a credit-card-sized plastic card on which cholesteric
`liq11id crystals are painted. Ordinarily, the card is black. One
`presses the card between thumb and index finger for 15
`seconds. Ifthe color changes to blue, the card indicates that
`finger temperature is high and the subject is relaxed. If the
`color changes to red, the subject's finger temperature is low,
`indicating tension.
`Cholesteric liquid crystals are also used as additives in a
`TN and super TN (STN) LCDs, which will be discussed later.
`
`In. DYNAMIC—SCA'I'I'ERlNG MODE—AMERICA'S AGILITY IN
`TAIGNG A NEW IDEA AND DEMONSTRATING ITS FEASIBILITY
`
`The development of LCDs started at RCA Laboratories in
`Princeton, NJ.
`
`A. Williams Domain
`
`In 1962, Richard “Williams of RCA found that liquid crys-
`tals had some interesting electrooptic characteristics [7],
`He sandwiched a liquid crystal p-azoxyanisole (PAA), a neg-
`ative nematic type liquid crystal, between two glass plates.
`The range over which it exhibited the liquid-crystal phase
`was from 1 17 °C to 134 °C. The liquid-crystal specimen be-
`tween the glass plates was heated to a liquid-crystal tpera-
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`RCA Laboratories’ sponsorship. In those days, young scien-
`tists and engineers were in great demand. RCA Laboratories
`recruited top-notch talent and financed their graduate edu-
`cation while enabling them to work part time and summers
`at the laboratory on meaningful research projects. Heilmeier
`first worked for over two years in the then emerging field
`of solid-state microwave devices. However, as an ambitious
`young scientist, he was wondering whether to stay in the
`rather established solid-state microwave field or enter the
`more fascinating and risky field of organic semiconductors.
`At around the same time, Heilmeier was attracted to the ex-
`periments on the Williams domain. He selected a strong dye
`whose molecules were cigar shaped. The dye was pleochroic;
`it absorbs light when the direction of polarization of linearly
`polarized light is in the direction of its long axis and transmits
`light when the direction of polarization is not in the direction
`of the long axis. He doped the nematic liquid crystal, butoxy
`benzoric acid (p-type 147 C–161 C), with the dye. The
`cigar-shaped dye molecules aligned parallel with the liquid
`crystals. Here, the dye is called the guest and the liquid crys-
`tals are called the host. The mixture was sandwiched between
`two glass slides coated with transparent tin oxide electrodes
`and placed under a microscope with a hot stage. A dc voltage
`of several volts was applied and they watched the cell change
`color from red to colorless as a function of the applied field
`[10]. As seen in Fig. 9, when no voltage was applied, the
`guest and host molecules were aligned at right angles with
`the direction of incident light and therefore absorbed light
`and appeared colored. As the electric field was applied, the
`guest dye molecules were reoriented along with the host ne-
`matic liquid-crystal molecules. They were now aligned par-
`allel to the direction of incident light and the mixture became
`transparent. It was found almost immediately that the effect
`was more dramatic with a polarizer in place. The device was
`drawing a very small electric current, less than a microwatt of
`power per square centimeter and they were switching color
`with voltages substantially smaller than those of CRTs—less
`than 10 V for liquid-crystal dye mixture versus more than
`1000 V for CRTs. This was in the fall of 1964. Heilmeier
`thought a wall-sized flat-panel color TV was just around the
`corner. As we will see, that realization took another quarter
`century.
`When Heilmeier demonstrated this effect within the labo-
`ratories, the people there became excited. Vladimir Zworkin,
`known to many in the field as the father of television, heard
`about the experiment and summoned Heilmeier to his of-
`fice to find out why people in the laboratories were so ex-
`cited. Heilmeier explained how he had “stumbled” onto the
`guest-host color switching effect. He never forgot Zworkin’s
`reflective reply: “Stumbled perhaps, but to stumble, one must
`be moving.” Later, in 1982, the guest-host mode combined
`with an AM drive would be used in a wristwatch television.
`
`C. Dynamic-Scattering Mode
`There were obvious problems with the guest-host effect.
`The dyes and their liquid-crystal hosts were not stable over
`long periods of time in applied fields, the effect was sen-
`sitive to surface orientation effects, and it required heating
`
`Fig. 8. Williams domains in p-azoxyanisole liquid crystal. The
`vertical line about 1/3 of the way from the right border is the edge
`of the strip of transparent conductive coating. To the right of this,
`there is no field in the liquid. To the left, there is a 1-kHz ac field
`of 2500 V/cm directed perpendicular to the plane of the page.
`Specimen thickness is about 50 m and temperature is 125 C [8].
`
`ture by supporting one of the glass plates on a heating stand.
`Each plate had a transparent tin oxide conductive coating on
`its inner faces and appropriate leads for making contact to
`an external circuit. Spacing between the plates was about 50
`m. He used a strip of conducting coating, which was less
`than the width of the glass plate. This allowed simultaneous
`observation of adjacent regions of the same specimen with
`and without an electric field.
`By applying an electric field perpendicular to the surface
`of the glass, he observed the appearance of a regular pattern
`in the area where the electric field was applied. As shown in
`Fig. 8, the pattern consisted of an array of long parallel re-
`gions, which he referred to as “domains.” Either alternating-
`current (ac) or direct-current (dc) voltage produced the do-
`mains. An ac voltage of 1 kHz was used where possible be-
`cause the ac voltage produced a somewhat more stable pat-
`tern and electrochemical deterioration of the liquid was min-
`imized. The electrical resistivity of the liquid crystals was
`approximately 10
`cm. This indicated that any ionic impu-
`rities that might be present were there only in small amounts.
`He reported that none of the effects could be due to electro-
`chemical deposition of the material, since the current flow
`was much too small to produce the effects in the required
`time. An ac signal of around 12.5 V was required, which
`means an electric field of about 2500 V/cm. He concluded
`that the domains were due to ordering in the liquid of a kind
`that had not previously been recognized. He demonstrated
`the feasibility of liquid crystals as electrooptical elements for
`display devices. This was a forerunner of the LCD. The phe-
`nomenon he discovered is now referred to as the “Williams
`domain.”
`
`B. Guest-Host Mode
`The development of the first LCD is well described by
`Heilmeier [9]. Some of the following is taken verbatim from
`his article.
`In 1961, Heilmeier had finished his written and oral ex-
`amination for the Ph.D. degree at Princeton University under
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`Fig. 9. Guest-host cell [4].
`
`to maintain the host in its nematic phase. RCA scientists
`tackled these problems on all fronts. In late 1964, they
`observed an interesting effect in certain classes of nematic
`liquid crystals—those with n-type [11]. The materials that
`yielded the best performance were members of a class of
`organic compounds known as Schiff’s bases. They found the
`compound anisylidene para-aminophenylacetate (APAPA)
`to be of particular interest. Its nematic range was from 83 C
`to 100 C. In an applied field, these materials exhibited
`a marked turbulence that
`turned them from transparent
`to milky white. The milk-white appearance required no
`polarizer to observe; it was purely a light scattering effect.
`Heilmeier discovered a very efficient way to electronically
`control the reflection of light. The rise time of 1–5 ms and
`decay times of less than 30 ms together with dc operating
`voltages in the 10–100-V range made the new mode at-
`tractive for such applications as alphanumeric indicators.
`Reflective contrast ratios of better than 15 to 1 with effi-
`ciencies of 45% of the standard white were demonstrated.
`He named it DSM. It was the first demonstration that those
`obscure materials called liquid crystals could be made into
`something useful. The LCD was born.
`The dynamic-scattering process occurs in the following
`manner [12]–[14] (see Fig. 10).
`
`1) Nematic liquid crystals are aligned perpendicular to
`the parallel plates.
`2) Applying an external field perpendicular to the plates,
`liquid crystals are aligned in a direction parallel to the
`plates because of the n-type.
`3) In nematic liquid crystals, the electrical conductivity
`in the direction along the long axis is larger than in the
`short-axis directions, which causes charge buildup.
`4) The induced field and external field give rise to a shear
`torque on the molecules, which causes a circular mo-
`tion of the molecules. This state may correspond to the
`Williams domain.
`
`5) By further increasing the external field, the molecules
`go into a mechanically unstable state or turbulence.
`The molecules now randomly scatter the light incident
`on the molecules and appear milky white.
`The process is sometimes called an electrohydrodynamic in-
`stability. In Europe, it is referred to as the Carr–Helfrich ef-
`fect.
`It was clear that for dynamic scattering to have a major
`impact, RCA was going to need room-temperature nematic
`materials. Joel Goldmacher, Joe Castellano, and Luke Barton
`went to work on the problem and in a relatively short pe-
`riod of time, developed a mixture of Schiff’s base mate-
`rials that were nematic at room temperatures [15]. With these
`materials in hand, Heilmeier, Louis Zanoni, and other RCA
`engineers designed and fabricated prototype devices based
`on DSM. Alphanumeric displays, windows with electron-
`ically controlled transparency, static pictorial displays (see
`Fig. 11), an all electronic clock with a liquid-crystal readout,
`and liquid-crystal cockpit displays were fabricated. These
`crude prototypes excited everyone at RCA.
`On May 28, 1968, RCA held a press conference at its head-
`quarters at Rockefeller Plaza, New York. They proudly an-
`nounced the discovery of a totally new type of electronic dis-
`play [16]. The display was dramatically different from tra-
`ditional CRTs. It was lightweight, consumed little electrical
`power, and was very thin. The press conference drew the at-
`tention of scientific and industrial communities all over the
`world. This announcement initiated the development of dig-
`ital watches in the U.S., Japan, and Germany and the work on
`pocket calculators in Japan. At the same time, it led to further
`scientific work in Germany, Switzerland, and the U.K.—par-
`ticularly for the synthesis of new liquid-crystal materials suit-
`able for use in display applications.
`
`D. Aftermath
`Naturally, Heilmeier wanted to see his invention evolve
`into RCA products. He went
`to company headquarters
`
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`Fig. 10. Mechanism of DSM. (Courtesy of T. Wada.)
`
`Fig. 11. Heilmeier demonstrates a static DSM display [16].
`
`and convinced RCA to go into the business of LCDs. The
`task was given to the Solid-State Division in Sommerville,
`NJ, which was responsible for the design and production
`of semiconductor devices. However, Heilmeier quickly
`received negative responses from the naysayers. Liquid
`crystals were not “silicon.” They were “dirty” by semicon-
`ductor standards. They were liquids. They were too easily
`duplicated. They were said to be too difficult to make. These
`
`were some of the many reasons the product division gave
`for its failure to commercialize LCDs.
`At the time, RCA owned a substantial amount of busi-
`ness in CRTs. Top management eventually rejected the idea
`of LCDs because they represented a threat to their existing
`CRT business.1 According to Heilmeier [17]: “The people
`who were asked to commercialize (the technology) saw it
`as a distraction to their main electronic focus.” In 1970, he
`gave up, accepting an appointment as a White House Fellow
`working in the Department of Defense as a Special Assis-
`tant to the Secretary of Defense. The term of the fellowship
`was for one year and he was supposed to come back to the
`original position after the assignment was completed, but it
`was obvious to everyone that he would never come back to
`Princeton. Later, he became the president of Bell Commu-
`nication Research Inc., the research arm of the Baby Bells.
`In 1987, RCA Laboratories merged with Stanford Research
`Institute, Menlo Park, CA.
`Richard Williams, when recalling the early days, has
`said, “If it had continued the work, RCA would have never
`achieved a commercial success.” It had to await the devel-
`
`1Section VI describes that U.S. control of the CRT business was precisely
`why the U.K. went into LCD research and succeeded in formulating com-
`mercially usable liquid crystals.
`
`KAWAMOTO: THE HISTORY OF LIQUID-CRYSTAL DISPLAYS
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`
`opment of liquid-crystal materials and amorphous silicon
`(a-Si) technologies, both of which were yet to come from
`Europe. Those developments altogether have taken a quarter
`of a century. Heilmeier would have not achieved success
`had he stayed with liquid-crystal technologies.
`
`IV. THE POCKET CALCULATOR—JAPAN’S SPEED IN
`COMMERCIALIZATION
`
`In late 1968, a team from NHK (Japan Broadcasting
`Corporation) visited Heilmeier at Princeton. They had been
`making a documentary called “Firms of the world: Modern
`alchemy.” The documentary aired in January 1969. At that
`time, RCA was a giant in the electronics industry and had
`led the industry with innovations such as audio records,
`radio, and color television; all had been inspired and their
`developments had been guided by RCA’s spiritual leader,
`David Sarnoff. A liquid-crystal section of the documentary
`was rerun in 1983. At its May 1968 press conference, RCA
`did not want to disclose the name of th