VALEO EXHIBIT 1038
`Valeo v. Magna
`IPR2015-____
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`VALEO EX. 1038_001
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`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
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`SOCIETY OF AUTOMOTIVE ENGINEERS,
`
`INC.
`
`400 Commonwealth Drive, Warrendale, Pa. 15096
`
`An Automotive
`Instrument Panel Employing
`Liquid Crystal Displays
`
`George W. Smith, Michael Kaplit,
`and Daniel B. Hayden
`Research Labs,General Motors Corp.
`
`International Automotive Engineering
`Congress and Exposition
`Cobo Hall, Detroit
`February 28 - March 4, 1977
`
`770274
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`VALEO EX. 1038_002
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`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
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`Copyright © Society of Automotive Engineers, Inc. 1977
`All rights reserved.
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`VALEO EX. 1038_003
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`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
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`770274
`
`An Automotive
`Instrument Panel Employing
`Liquid Crystal Displays
`
`George W. Smith, Michael Kaplit,
`and Daniel B. Hayden
`Research Labs, General Motors Corp.
`
`been described by Trenne and Stephan (1) and
`Nolan (4). However, for the purposes of this
`discussion it is worthwhile to review briefly
`some of the features of these devices.
`A.
`OPERATING PRINCIPLES - The operating
`principles of a LCD are based on the optical
`anisotropy of a unique fluid state of matter -
`nematic liquid crystals.
`The molecules of
`these materials prefer to orient themselves
`parallel to one another.
`By changing their
`orientation electrically it is possible to con
`trol light incident on the liquid crystal.
`Although several modes of LCD operation have
`been developed,
`the devices which have attracted
`the greatest interest are those which scatter
`light and those which control the polarization
`of light. Each of these modes can be operated
`either in transmission (by allowing light to
`pass completely through the device) or in
`reflection (by placing a mirrored surface at
`the rear of the device). Polarization-control
`ling LCDs require one or more polarizers for
`their operation.
`The devices under evaluation in our auto
`mobile instrument panel are all of the polari
`
`ABSTRACT
`
`large scale
`THE RAPID DEVELOPMENT of low cost,
`integrated circuitry has increased the likeli
`hood that electronic display devices will make
`their appearance in automobile instrument pan
`els in the near future (1-5).* Although a
`number of electronic display technologies have
`potential for instrument panel use (1,4),
`further development is needed to satisfy all
`requirements for such an application (1).
`Liquid crystal displays (LCDs) are particularly
`strong candidates for future IPs. Their auto
`motive applications are currently under study
`at Smiths Industries in Great Britain (2,3) and
`at General Motors in this country.
`The present
`report describes a liquid crystal display sys
`tem which has been installed and evaluated in
`a 1975 Chevrolet Monte Carlo.
`
`OPERATING AND DESIGN CONSIDERATIONS OF LCDs
`
`The nature and operating characteristics
`of LCDs and other electrooptic displays have
`
`*Numbers in parentheses designate References
`at end of paper.
`
`An instrument panel cluster consisting
`of five twisted nematic liquid crystal dis
`plays has been installed and tested in a 1975
`Chevrolet Monte Carlo.
`The displays are:
`warning indicators, speedometer, clock/odometer,
`fuel gauge, and transmission indicator (PRNDL).
`Four modes of operation for the warning indica
`
`transmissive, color
`tors have been evaluated:
`transmissive, reflective, and color transreflec
`tive.
`The remaining displays all operate in
`the reflective mode.
`A heater system allows
`operation over a -40°C to +80°C temperature
`range.
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`they
`zation-controlling variety. Specifically,
`twist the light polarization 90° in the "off"
`state, hence,
`they are called twisted nematic
`(TN) LCDs.
`The construction and operation of a
`reflective TN LCD is illustrated schematically
`in Fig. 1.
`A suitable liquid crystal is sand
`wiched between two glass plates, each of which
`has a transparent electrode coating on its
`inner surface.
`A crossed polarizer/analyzer
`pair is mounted on the outer glass surfaces and
`a diffuse reflector is attached to the rear of
`the analyzer film.
`In the off-state the liquid
`crystal molecules, represented by elongated
`ellipses, are aligned so that their axes de
`scribe a 90° twist on passing from one side of
`the LCD to the other (6).
`The twist causes the
`plane of polarization of incident plane polar
`ized light (due to polarizer P) also to describe
`a 90° twist so that it will pass through analy
`zer A, be reflected at the diffuse reflector R,
`and re-emerge through the analyzer, cell, and
`polarizer. Thus in the off-state the cell
`reflects light. Because the liquid crystal has
`a greater dielectric constant along the molecu
`lar axis than perpendicular to it, application
`of a low voltage across electrodes E realigns
`the molecules normal
`to the cell surface.
`The
`liquid crystal is now uniaxial and does not
`rotate the light polarization. Thus light can
`no longer pass through the crossed polarizer/
`analyzer pair. As a consequence,
`in the on
`state light is absorbed and the cell appears
`dark.
`A schematic plot of reflected intensity I
`vs applied voltage V is shown in Fig. 1.
`B.
`ADVANTAGES OF LCDs - Liquid crystal
`displays compare quite favorably with other
`electronic display systems (1). Their low
`power and voltage requirements make them di
`rectly compatible with integrated circuitry.
`Reflective TN LCDs have excellent visibility
`and contrast in bright sun.
`The ease with which
`
`their electrode pattern can be changed gives
`them great flexibility in design.
`In addition
`use of colored polarizing films gives TN LCDs
`one- or two-color capability (7). Like all flat
`panel displays liquid crystal devices offer the
`promise of greatly reduced bulk in future
`instrument panels.
`C.TEMPERATURE RANGE - At present the
`operating temperature range of a liquid crystal
`display has a lower limit of about -20°C due to
`increasingly sluggish response as the tempera
`ture is decreased.
`In order to extend the
`effective range, simple heater systems can be
`employed. Furthermore,
`the search for new,
`lower temperature materials continues at a
`number of laboratories.
`Two frequency address
`ing schemes (8) and thinner cells are also
`approaches being used to shorten the response
`time.
`In the early years of LCD research
`device reliability was a problem; however, life
`times in excess of 5 years are now claimed as a
`result of hermetic seal
`techniques or new mate
`rials.
`D.ILLUMINATION OF LCDs - Since they are
`passive (light controlling) rather than active
`(light emitting) LCDs require a light source
`for visibility. During the day this illumina
`tion is, of course, provided by the ambient
`light. At night incandescent bulbs are gener
`ally required.
`a. Daytime Operation - Reflective TN LCDs
`give excellent contrast in bright sunlight.
`However,
`the contrast of some transmissive LCDs
`may decrease somewhat in direct sunlight -
`particularly when colored filters or colored
`polarizers are employed in the device (as is
`desired in a warning indicator).
`The viewing
`angle of LCDs
`(90° to 120°) is a bit narrower
`than for some other displays, which can make
`visibility from the passenger seat somewhat
`limited.
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`b. Nighttime Operation - At night illumin
`ation can be accomplished in several possible
`ways:
`lighting from the front; edge lighting;
`or rear illumination (through either a transmit
`ting polarizer or one with a partially transmit
`ting reflector -- a "transreflector"). Careful
`attention must be paid to the design of the
`lighting system to achieve maximum visibility
`and contrast.
`
`PRESENT SYSTEM
`
`THE INSTRUMENT PANEL - The initial
`A.
`instrument panel configuration as conceived by
`GM Design Staff was that of Fig. 2.
`The five
`displays shown are:
`a transmissive warning
`indicator panel and reflective fuel gauge,
`speedometer, clock/odometer, and transmission
`indicator.
`LCDs for this program were fabricated
`according to the schematic configuration of
`Fig. 1.
`The device cell separation is main
`tained by a 12.5 µm Teflon spacer around the
`perimeter. Cells were sealed by epoxy. Com
`mercially available nematic liquid crystal mate
`rials were used. However, it was necessary to
`add a small quantity of cholesteric liquid
`crystal to improve uniformity of molecular
`alignment (9). Electrode patterns for both
`front and back planes of
`the five LCDs were
`etched using standard techniques.
`The front and
`back electrode pattern for the speedometer are
`shown in Fig. 3.
`At night all reflective LCDs are front lit
`by incandescent bulbs recessed in the overhang
`above each display device.
`The transmissive
`telltale display was illuminated from the rear.
`Future LCD instrument panels will require in
`creased attention to optimization of the light
`ing configuration.
`The four reflective displays remained es
`sentially unchanged during the program. How
`ever, four different warning indicator config
`urations were evaluated -- two transmissive, one
`reflective, and one transref lective. We shall
`discuss these configurations briefly.
`1) Transmissive Warning Indicators - The
`first warning indicator tested in the car was
`
`a transmissive twisted nematic cell with nine
`separately addressable warning functions (Fig.
`2). Attached to the front surface of the device
`was a colored louvered plastic sheet, which
`helped to shield out direct rays of the sun and
`gave the device its red color. Unfortunately
`the visibility of this LCD was poor under high
`ambient light conditions.
`2)Two-Color Transmissive Warning Indica
`tor - The colors of this device were attained by
`use of blue and red colored dichroic polarizers
`attached to the rear surface (instead of the
`usual neutral polarizer).
`It was felt that use
`of two colors would improve the appearance and
`also enhance the driver's ability to discrimin
`ate between warning and informational displays.
`Thus "Cruise" and "Bright" functions were dis
`played in blue. While "Alt," "Oil," "Temp,"
`"Brake Failure," "Door," "Belts," and "Park
`Brake" were shown in red. Furthermore, it was
`also believed that this system would have in
`creased visibility in bright sun. Although
`visibility was enhanced by this new system and
`appearance was improved by the use of color,
`direct sun through the driver's side window
`could diminish the contrast under some condi
`tions.
`3)Transreflective Color Warning Indica
`tor - Daytime visibility was improved over that
`for a transmissive color telltale by replacing
`the rear color polarizers with color polarizers
`backed by a transreflective layer (Fig. 4).
`4)Reflective Warning Indicator - The
`warning panel currently mounted in the car is
`that shown in Fig. 5.
`The use of a reflective
`device eliminated the "wash out" problem.
`Because this display does not attract the dri
`ver's attention as effectively as a colored
`display, a bell was added which is activated
`when a telltale warning is on.
`VALEO EX. 1038_006
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`At present transreflective and reflective
`displays seem best suited for use as warning
`indicators.
`The present instrument panel is shown in
`Fig. 6.
`The photograph shows the uniformity and
`harmony of design which is possible from such a
`single flat panel
`technology.
`It is also evi
`dent that there is room for additional display
`functions. Not apparent from the picture is the
`saving in space behind the instrument panel, a
`consideration which is important in small cars.
`B.LCD HEATER SYSTEM - By attaching a flat
`panel heater to the rear of each LCD cell (see
`Figs.
`7 and 8), ambient
`temperatures as low as
`-40°C could be tolerated. Using power levels of
`about 0.4 watts per cm2 of cell area, warmup
`from -40°C to +10°C could be achieved in about
`1 minute.
`The heater power system is thermo
`statically controlled to prevent overheating of
`the LCDs.
`The heater system has performed sat
`isfactorily both in cold room tests and under
`normal Detroit winter driving conditions.
`C.ELECTRONIC SYSTEM FOR LCDs - Drive
`circuitry for electronic displays has been dis
`cussed previously (1,10). We shall therefore
`confine our remarks to salient features of the
`present system. Figure 6 shows the set of nine
`warning indicators,
`the fourteen segment bar
`graph fuel gauge,
`the two digit speedometer,
`the six digit clock-odometer, and the drive
`gear indicator (PRNDL). These twisted nematic
`LCDs replaced their electromechanical counter
`parts on the instrument panel.
`In the picture
`the fuel gauge indicates that the gas tank is
`about 3/4 full. When indicating empty all four
`teen segments are off (i.e. not seen) and the
`"E" for empty flashes on and off once a second.
`The "F" for full is always on.
`The clock and
`odometer share a six digit display.
`For dis
`playing mileage all six digits are available to
`indicate from 0.0 to 99999.9 miles.
`For the
`time display only the middle four digits are
`used.
`The period and colon are switched as
`necessary.
`For the drive gear display only the
`
`shown in Fig. 6 in the P position for park,
`box,
`moves.
`By law,
`the drive gear letters PRNDL2L1
`must be visible at all times when the ignition
`is on.
`The operation and construction of twisted
`nematic field effect LCDs have been described
`above.
`The electrical equivalent of a multi
`section cell is parallel plate capacitors, one
`for each section, sharing a common plate (the
`back plane in LCD terminology) as shown schemat
`ically in Fig. 9a.
`The individual capacitors
`represent areas,
`the reflection or transmission
`of which are to be controlled by applying a
`voltage between the back plane and the appro
`priate section.
`LCDs have a far greater life
`time when ac driven than when dc driven. Figure
`9b shows how a section is turned on or off using
`two 50% duty cycle pulsating dc signals 180° out
`of phase, or in phase respectively. The cells
`for the test car require about 8 volts peak-to
`peak to completely change state, on to off or
`off to on.
`
`The senders for the car and the signal con
`ditioning required to drive the displays are:
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`The senders are those used on a convention
`al car with one exception: a sender producing
`6000 pulses/mile (3729 pulses/km) was attached
`to the speedometer shaft to provide a signal for
`both the odometer and speedometer.
`The fuel level sender is a 0 ohm to 90 ohm
`variable resistor.
`Its resistance is propor
`tional to the fuel level. One ohm should cor
`respond to an empty indication on the fuel gauge
`and 88 ohm a full indication. As is evident,
`five of the nine warning senders are switches to
`ground (STG) and another two are switches to the
`12 volts (STV) of the car battery.
`The drive
`gear sender (PRNDL)
`is also a STG.
`Because in a conventional car the alterna
`tor and seat belt warning lights are essential
`components of their respective circuitry, a 10
`ohm resistor was substituted for each bulb.
`When a malfunction occurs, one end of the resis
`tor is pulled down (connected)
`to about 1 volt
`above ground by a transistor.
`(There is a volt
`age drop of about 1 volt across a p-n junction
`in the transistor.) Thus 12 volts at the resis
`tor transistor junction indicates all is well
`and about 1 volt at this junction indicates a
`malfunction.
`Commercially available complementary sym
`metry metal oxide semiconductor (CMOS) compon
`ents were chosen to control the displays since
`they meet all the following system requirements:
`1)Operate from a nominal 12 V car battery,
`i.e., from 8 V to 14 V without
`the need for
`a buffering power supply.
`2)Have a voltage output sufficient to produce
`the 8 V peak to peak ac drive needed for
`the LCDs.
`3)Have high noise immunity.
`4)Operate at low power levels.
`5)Have a useful operating temperature range
`from -20°C to 100°C and storage temperature
`range from -40°C to 120°C.
`Discrete components that cannot become part
`of a large scale integrated circuit (LSI) were
`avoided.
`The complete instrument panel system is
`shown schematically in the block diagrams of
`Fig. 10.
`The present circuit module is shown in
`Fig. 11.
`The electronic circuitry performs sat
`isfactorily in the car.
`Power consumption for
`the electronics and the displays during driving
`is 1/2 watt, and 1/5 watt is consumed by the
`odometer pseudomemory and clock when the igni
`tion is off.
`The current production clock uses
`about 0.36 watts. Thus circuitry did not cause
`excessive battery drain.
`It is expected that
`use of LSI would permit substantial reduction
`of
`the size of the circuitry package.
`
`SUMMARY
`
`We have installed a liquid crystal display
`(LCD) system in an automobile instrument panel.
`By means of heaters, it is capable of operating
`over a -40°C to +80°C temperature range.
`LCDs
`
`have a number of very positive attributes for
`automotive use:
`low voltage and power require
`ments, excellent visibility in bright sun, flex
`ibility of design, color capability, and reduced
`bulk. Additional work is still required to
`increase their temperature range (without heat
`ers) and shorten their response times. Never
`theless liquid crystal display technology is a
`viable alternative for future instrument panels.
`
`ACKNOWLEDGMENTS
`
`The authors thank Lawrence W. Faloon and
`Frank S. Lopez of the General Motors Design
`Staff for their important contributions to this
`project.
`
`REFERENCES
`
`1.M. U. Trenne and J. J. Stephan, "Elec
`tronic Display Systems in the Automobile," Auto
`motive Electronics II. Warrendale, PA: Society
`of Automotive Engineers, Inc., Paper 750365,
`1975.
`
`2.David Scott, "Advanced Circuits and
`Displays for Electronic Instrumentation," Auto
`motive Engineering, June 1975.
`3.Ken Garrett, "Brightening up the Dash
`board," New Scientist, 27 May 1976.
`4.J. F. Nolan, "Survey of Electronic Dis
`plays," Automotive Electronics II, Warrendale,
`PA: Society of Automotive Engineers, Inc. Paper
`750364, 1975.
`[See also references cited in
`this publication.]
`5.H. Nissley and R. J. Boike, "Electronic
`Display Applications in Instrument Panel Design,"
`ibid, Paper 750366, 1975.
`6.The molecular alignment can be produced
`by rubbing the electrode surfaces [see M. Schadt
`and W. Helfrich, Applied Physics Letters, Vol.
`18, 15 Feb. 1971], or by deposition of a thin
`film at an oblique angle [see J. L. Janning,
`Appl. Phys. Letters, Vol. 21, 15 August 1972].
`7.S. Kobayashi and F. Takeuchi, "Multi
`color Field-Effect Display Devices with Twisted
`Nematic Liquid Crystals," Proceedings of the
`S.I.D. Vol. 14, No. 4, Fourth Quarter 1973.
`8.H. K. Bucher, R. T. Klingbiel, and
`J. P. Van Meter, "Frequency-Addressed Liquid
`Crystal Field Effect," Appl. Phys. Letters,
`Vol. 25, 15 August 1974.
`9.Alan Sussman, "Electrooptic Liquid
`Crystal Devices: Principles and Applications,"
`IEEE Transactions on Parts, Hybrids, and Packag
`ing, Vol. PHP-8, No. 4, December 1972.
`
`10. G. R. Seaton and D. A. Wayne, "Tech
`niques for Driving Digital Displays," Automo
`tive Electronics II. Warrendale, PA: Society
`of Automotive Engineers, Inc., Paper 750367,
`1975.
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`VALEO EX. 1038_009
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`451
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`452
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`VALEO EX. 1038_011
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`VALEO EX. 1038_012
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`VALEO EX. 1038_013
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`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
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`This paper is subject to revision. Statements and opinions
`advanced in papers or discussion are the author's and are
`his responsibility, not the Society's, however, the paper has
`been edited by SAE for uniform styling and format. Dis
`cussion will be printed with the paper if it is published
`
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`12 page booklet.
`Printed in U.S.A.
`VALEO EX. 1038_014
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