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`Flat Dot Matrix Display Module for Vehicle Instrumentation
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`Flat Dot Matrix Display Module for Vehicle Instrumentation
`
`Technical Paper
`
`Paper #: 871288
`
`DOI:
`
`10.4271/871288
`
`Published: 1987-11-08
`
`Citation:
`
`Otsuka, T., Ogasawara, Y., and Suzuki, Y., "Flat Dot Matrix Display Module for
`Vehicle
`Instrumentation,"
`SAE
`Technical
`Paper
`871288,
`1987,
`doi:10.4271/871288.
`
`Author(s): Tatsumi Otsuka
`
`Yasuyuki Ogasawara
`
`Yoshiyuki Suzuki
`
`Affiliated:
`
`Yazaki Corp.
`
`Abstract: Due to the recent increase in safety and operational information
`supplied to vehicle operators, an important need has arisen; the
`development of an effective display unit which uses a minimal amount
`of dashboard space.
`
`A flat dot matrix LCD module is one possible satisfactory solution, but it
`is somewhat limited in terms of response time and viewing angle.
`
`This paper presents a review of the recent progress and projected
`future trends
`in LCD technology as
`it
`is applied to vehicle
`instrumentation. In addition, the paper will discuss the design
`methodology, electro-optical properties, and function of three types of
`flat dot matrix display modules which have an intermediate number of
`picture elements.
`
`Sector:
`
`Automotive
`
`Topic:
`
`Simulation and Modeling Displays
`
`Project management
`
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`©2014 SAE International. All rights reserved.
`
`http://papers.sae.org/871288/
`
`1/1
`
`VALEO EX. 1017_001
`
`

`

`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
`
`871 288
`
`288.1
`
`Flat Dot Matrix Display Module for Vehicle Instrumentation
`
`Tatsumi Otsuka, Yasuyuki Ogasawara, Yoshiyuki Suzuki
`
`YAZAKI Corporation
`
`ABSTRACT
`Due to the recent
`increase in safety and operational
`information supplied to vehicle operators, an important need
`has arisen; the development of an effective display unit which
`uses a minimal amount of dashboard space.
`
`A flat dot matrix LCD module is one possible satisfactory
`solution, but it is somewhat limited in terms of response time
`and viewing angle.
`
`(plasma display), CRT (cathode ray tube), and EL (Electro
`Shown in Table 1 is a comparison
`Luminescent display).
`of dot matrix display characteristics of the devices employed
`at present.
`From among them we chose the multiplexing TN LCD
`(Twisted Nematic LCD) as the device to be used for the display
`module with small and intermediate numbers of picture ele·
`ments, as it excels others in cost, ease of operation (low power
`consumption, low driving voltage) and flatness.
`
`This paper presents a review of the recent progress and
`projected future trends in LCD technology as it is applied to
`vehicle instrumentation.
`In addition,
`the paper will discuss
`the design methodology, electro-optical properties, and func(cid:173)
`tion of three types of flat dot matrix display modules which
`have an intermediate number of picture elements.
`
`INTRODUCTION
`Information now supplied to vehicle operators is in a wide
`range starting with the most fundamental ones such as the
`vehicle speed,
`fuel
`level, water
`temperature, warning, and
`trip·odo meter.
`
`information is also provided
`However, much additional
`to monitor vehicle performance inclUding the following; elapsed
`time and distance;
`fuel consumption rate; driving range on
`reserves; estimated time of arrival; instantaneous and average
`vehicle speeds;
`interior and exterior ambient
`temperature;
`air conditioning; maintenance
`requirement; diagnosis; and
`entertainment and traffic information.
`Multidisplay of all such information can be performed
`with a CRT employed as the information center of a large
`number of picture elements.
`[1] On the other hand,
`there
`is a strong demand for information centers of small and in(cid:173)
`termediate numbers of picture elements in order to display
`all
`the information and specifically to minimize the space for
`the dashboard.
`[2]
`
`In response to such needs, three types of display modules
`were developed. Among the electronic display devices currently
`employed in vehicles are LED (light emitting diode), VFT
`(vacuum fluorescent tUbe), LCD (Liquid Crystal Display), PDP
`
`However, the muitiplexing TN LCD gives inferior legibility
`compared to other devices. Therefore, its legibility must be
`improved if TN LCD is to be used in the module.
`
`This report presents an outline of the design developed
`the
`display module to improve the legibility, and the
`for
`characteristics of the module.
`
`Table. 1 Comparison of Dot Matrix Display
`Capability by Types of Devices
`
`TULCD
`
`Mulll·
`plex.ing
`
`AcHvn
`address·
`ing
`
`6
`
`iQl
`
`6
`
`<-
`
`iQl
`
`iQl
`
`6
`
`' -
`g
`
`©
`
`iQl
`
`iQl
`
`6
`
`Display
`Capacity
`
`Flalness
`
`Lngibilily
`
`Color
`
`Ease 01
`Opernlion
`
`Cosl
`
`Reliabllily
`
`CRT
`
`EL
`
`PDP
`
`VFT
`
`LED
`
`<.
`
`.
`
`/,
`
`6
`
`«:'9
`
`~<
`
`g
`
`Cd)
`
`>'
`
`y
`
`..
`
`....
`
`(EJ)
`
`>:
`
`6
`
`6
`
`©
`
`x
`
`;<
`
`.
`
`6
`
`I
`
`~<
`
`6
`
`-
`
`g ... Excellent
`
`·Good
`
`6···Fair
`
`x ···Poor
`
`VALEO EX. 1017_002
`
`

`

`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
`
`288.2
`
`PROBLEMS WITH MULTIPLEXING TNLCD
`In a dot matrix display I strip electrodes (column electrodes
`and row electrodes) are perpendicularly crisscrossed, each
`crossing of electrodes being considered one pixel which can
`be illuminated.
`In operating the matrix display, a column electrode acts as a
`scanning line and a row electrode as a signal
`line. Scanning
`lines are signaled one line at a time. At the same time, signal
`lines are given a selective or non~selective signal
`in response
`to the reaction of a pixel turned on or off on a scanning line.
`(i.e. whether it is lit or not.) This is the method called mul(cid:173)
`tiplexing.
`
`It has a shortcoming, however,
`in that when the number
`of scanning electrodes is increased, it causes a crosstalk effect
`(wherein the pixels are lit only half way). because a certain
`amount of voltage (bias voltage)
`is impressed upon other
`pixels not required to be lit up.
`In other words, as the number
`of scanning lines increases,
`there will occur undesirable phe·
`nomena such as the lowered brightness, less contrast narrower
`range of viewing angle, and slower response.
`
`The characteristic factors of an electronic device which
`determine the legibility of display are as follows;
`[3]
`i) displayarea
`ii) resolution (number of dots)
`iii) brightness, contrast
`iv) color
`v) afterimages created by time interval and shape
`of dispiay image
`vi) intermediate gradation (ie; half tone)
`
`In the multiplexing method, as the number of scanning
`lines is increased, .improvement is observed with regard to the
`display area, resolution, and the intermediate gradation, while
`the brightness and contrast are lowered. Therefore, in designing
`a module, it is important to consider the contents of the display
`and see how a display pattern can be formulated with the
`minimum number of scanning lines and with brightness and
`contrast as high as possible.
`
`MODULE SPECIFICATIONS AND OBJECTIVES OF
`DESIGN
`Specifications of three types of modules developed are
`given in Table 2 and their appearances in photos 1,2, and 3.
`
`Table. 3 Principal Objectives and Principal
`Related Factors
`
`Principal objectives
`
`Principal relaled factors
`
`I- Display pallerns
`
`1. Development of CRT dlspfay simulalion program
`
`2. Color matching
`
`3. Expansion 01 viewing
`angle dependency 01
`conlrasl raBo character-
`islics
`
`4.
`
`Improved response 1Ime
`at
`low temperature
`
`1. Development of CRT display simulalion program
`2. (Sol,ilion 01 color IiIl,ro1l4115116nll
`
`1. Seleclion of polarizer
`2. ReducHon 01 number 01 scanning lines
`3.
`ISoloclion olLGD mal,rial'lIangl
`
`1. Reduclion of number of scanning lines
`2. Development 01 healing unit
`3.
`(Seleclion 01 LCD materials)
`
`I
`
`Shown in table 3 is the relationship between the principal
`objectives and the principal related factors of the three module
`designes using a multiplexing TN LCD.
`
`This paper describes four of the six principal
`required to achieve an improved design.
`
`factors
`
`Table. 2 Module-3 Types
`
`Module Type
`
`Typ, 1
`
`Typ, 2
`
`Typo 3
`
`Usage
`
`Message display
`
`SymbGI display.
`Warning or mainle-
`nance
`
`Graphic display.
`for gauges, air condi-
`UGner. elc
`
`Form of Display Numerals. English
`alphabet KanjI. and
`Hi ragana
`
`Numerals. English
`alphabel. Kanji, and
`ISO symbols
`
`Numerals. English
`alphabet Kanji-ISO
`symbols. and Graphics
`
`Contents 01
`Display
`
`13 Warning messages
`13 Warning symbols
`3 mainlenance inslruc- 3 mainlenance Instruc-
`lions
`lians
`a gear-shill Inslrucl-
`agear-shill Instruct-
`ions
`ions
`Greetings. Time-piece
`Time-piece
`
`6 Warning symbols
`Gauge indicalion
`jlue!. waler tempera-
`lurej
`Gear-shill
`tions
`Air condHialling
`Speed
`
`instruc-
`
`Ncgative.
`lransrefleclive Iyp,
`
`IHegalill1l.
`transrefleclive type
`
`Negative.
`1ransparent
`
`Iype
`
`MonGchrome
`(yellow, black)
`
`Monochrome
`Iyellow. black}
`
`Mode
`
`Colors
`
`Ools
`
`3 calors
`(yellow. red. grcen. bla-
`ck)
`
`leteral /1 ollgiludinal
`D.76 D.37Imm}
`
`D.BD D.4Dlmm}
`
`48 x 200 dots
`
`1/12.1/24 dUly
`.. ·shilled
`1/5 bias
`.. ·common to bolh
`
`Dol sizl!
`D.55 x D.55(mm}
`Pilch
`
`D.llmm)
`Number of dots
`16x16D dols
`
`I.Dx I.Dlmmi
`
`1.3(mm)
`
`I 32 x 30 dols
`
`1/8 duty 1/4 bias
`
`Driving Duty
`
`1/16 dUly 1/5bias
`
`Photo 1 Type I Module
`
`VALEO EX. 1017_003
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`

`

`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
`
`288.3
`
`Photo 2 Type 2 Module
`
`Photo 3 Type 3 Module, Built into the Instrumentation Panel
`
`METHODOLOGY
`DETERMINATION OF DOT FORMS AND COLOR
`ARRANGEMENT BY DEVELOPMENT OF CRT DISPLAY
`SIMULATION PROGRAM - WhIle electrodes in a dot matrix
`are of simple composition, there is a great number of items for
`which the most appropriate condition would have to be sought
`in order to provide the best possible display within a limited
`number of dots, such as the form of dots (size, number, and
`pitch) and the selection of color filters. We therefore developed
`a software program for a CRT display simulation system com(cid:173)
`prising designs of liquid crystal display elements, and studied
`the feasibility of the desired display patterns.
`
`The contents of the program software are shown in Table
`
`4.
`
`The size and number of dots for the module were deter(cid:173)
`mined using this simulation system.
`
`the actual CRT and LCD displays are
`Comparisons of
`given in photos 4 and 5.
`
`Type 3 module has a more complex design of display
`than the other two.
`Furthermore it is necessary to provide
`either a red or green filter at each pixel within the liquid crystal
`cell, since three colors are used for the display, namely red (R),
`green (Gl, and yellow (Y).
`Therefore,
`the arrangement of these two colors was studied
`first.
`
`The arrangement of these two color comes in two types,
`longitudinal and skew.
`
`In the case of a linear display in longitudinal and lateral
`directions the longitudinal stripes will give clear edges, but when
`expressing diagonal lines or circles the skew stripes can provide
`a better looking design. Here the longitudinally striped arrange(cid:173)
`ment has been chosen, since module displays carry many ISO
`symbols and the ISO symbols themselves are generally compar·
`atively linear in shape. Results of study on the CRT display
`is shown in photo 6.
`
`Furthermore in order to determine the color dot size, it
`is necessary to check the possibility of producing a yellow
`colored display by means of red and green dots.
`In general, the
`following Equation (1) will express the condition under which
`two color dots are mixed and observed as one dot.
`
`Table. 4 Programming for Patterns
`
`Display
`Pallerns
`essages, lellers, numerals
`11 M
`osymbols, warnings
`2) IS
`rious indicalor displays
`31 Va
`aphic displays
`4) Gr
`
`<==>
`
`LCD Cell Eleclrodes
`1) Dol size, shape, and space
`2) Number 01 colors, color
`arrangement hue
`3) Dimensions 01 display area.
`aspecl ralio
`
`CRT Simulation Program
`16 bit 640 x 400 dais display
`Display in 16 colors oul 01 4096
`
`1) Capabilily 10 selec! lhe number 01 display pixels
`2) Capabilily 10 selecl lhe number 01 dols composing Ihe pixel
`3) Capabilily 10 selecl Ihe color filler lor each dol composing Ihe pixel
`4) Seleclion 01 dol sizes
`5) Capabilily 10 selecl Ihe ON·OFF display color in inlermedlale gradalion
`6) Arrangemenl and selection 01 coler fillers
`7) Capabilily el lermulating, slorlng and correcling Ihe designs
`
`CRT Display
`
`LCD Display
`
`Photo 4 Type 2 Module Simulation
`
`(1)
`y = altan (1/60'e)
`y:
`distance at which two dots are recognized as one dot.
`a:
`dot pitch.
`e:
`visual acuity.
`
`the distance between the dashboard and the operator
`If
`is 1000mm, and the visual acuity is e = 1.0, then it will give
`a = 0.3mm.
`
`VALEO EX. 1017_004
`
`

`

`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
`
`at Fig. 5 suggests the life under the condition of 25°C and 90%
`RH is approximately 2 x 104 hours.
`In another test under 90°C
`the characteristics could be maintained for more than 103
`hours. Although it will be necessary to also consider the field
`data, the polarizer seems to have a high probability of serving
`the purpose in a vehicle.
`In the case of the Type 3 module, the iodine type polarizer
`was selected for evaluation in the dashboard, since it would be
`built
`in the dashboard and protected from environmental
`stresses.
`
`288.4
`
`CRT
`Display
`
`LCD
`Display
`
`Photo 5 Type 3 Module Simulation
`
`However, other elements of module design such as the size of
`the display area and the number of scanning lines will not per(cid:173)
`mit the formulation of dots at such a pitch. Therefore, tests
`were carried out on a CRT display to ascertain the possibility
`of color mixing at dots of O.8xOAmm, which is closest to the
`mixing pitch.
`In fact, color mixing at this dot pitch was pos(cid:173)
`sible on an actually prepared LCD.
`
`Shown in Table 2 are the dot specifications finalized for
`the three types of modules.
`
`In order to obtain a wide
`SELECTION OF POLARIZER -
`viewing angle and high speed response, it is important, first of
`all, to select liquid crystal material of superior quality.
`[8]
`[9]
`But the viewing angle dependency of contrast ratio character(cid:173)
`istics hinges largely on the polarizer. Polarizers come in two
`types, the dichroic dye type and the iodine type. For vehicle
`instruments the dichroic dye type polarizer is normally used
`because of its durability against environmental stresses. How(cid:173)
`ever, the iodine type polarizer has superior optical characteristics
`(polarization and transmission). Fig. 1 illustrates the effect of
`viewing angle enlargement with an iodine type polarizer.
`
`in substrate has given the iodine
`improvement
`The recent
`type polarizer a greater durability against environmental stresses.
`An evaluation test has been carried out on the improved iodine
`type polarizer, which has become available.
`
`Fig.s 2,3.4 illustrate the color difference, polarization, and
`variation of trans mission of a single polarizer under the environ(cid:173)
`ment of 60°C and 90% relative humidity.
`
`a) longitudinal stripes
`
`b) skew stripes
`
`Photo 6 Color Arrangement on CRT Display
`
`Pholometer0
`
`135" ---'~
`
`90°
`
`45'
`
`180',/:; ~61:11 0'
`
`225'
`
`270 0
`
`315°
`Ughl source
`
`Measurement 01 contrast curve
`
`90'
`
`13 5 ° 45 °
`-;> High durabilily dichroic polarizer
`-
`-
`-
`-
`- - --:' Medium durabilitv iodine Iype polarizer
`
`""-"',
`fi
`4'
`./
`.....,--/
`
`I
`\
`
`0'
`
`s'
`
`20'
`IZ'
`15
`conlrast ralio
`
`225'
`¢=20'
`54Hz
`1/128,Iy
`1/5Bias
`Vdd= 19.5,
`
`270'
`
`Fromthe test results the variation at color difference .6.E~V=5
`is judged to be the life of the polarizer. The Arrhenius plot
`
`Fig. 1 Contrast Curve at rp = Constant
`
`VALEO EX. 1017_005
`
`

`

`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
`
`288.5
`
`I
`
`Ilumidily: 90% All constanl
`
`Perpendicular
`
`10'
`
`10'
`
`lligh durabilily
`
`1
`I
`
`IIIIIIIIII
`
`J
`
`I
`
`I
`
`10 1~
`l Medium durabilily
`,
`10t__J ~L
`
`25
`
`50
`
`I -~-~200
`100
`150
`Temperalure{' Cj
`
`Fig.5 Estimated Life by Arrhenius Plot
`
`Column ~::)
`driver
`
`•
`.~•'"
`
`100
`
`500
`Time{hrj
`
`1000
`
`Fig. 2 Variation of Color Difference
`
`,----~·_~-·---I
`
`High durabilily I
`100 I
`___________ J.
`
`,
`
`~ 95f.(cid:173)
`I
`
`90 t,
`
`Medium durability
`
`60' x 9D%AH
`
`, !L
`
`-.L ~__~,.
`100
`500
`Time{hr)
`Fig.3 Variation of Polarization
`
`'__
`1000
`
`40
`
`\ Medium dUl1lbilily
`Parallel
`/
`L_ . .t...,,- .. _---
`30 L
`'High durahllil y
`
`I"
`
`!
`
`60"X90%RH
`
`High durability
`
`10 (cid:173)
`
`I
`
`Medium durabilily ,
`i
`'___ '
`~_ -.L
`,
`I
`I ! p~endjCul~ r=_=:J.-.~_..J
`100
`500
`1000
`Time{hrj
`
`Fig. 4 Variation of Transmission
`
`Row eleclrodes
`
`U I
`
`111
`
`11-
`Sign~1 flnes
`
`MPU 1-------1
`
`Rnw ~river
`
`Fig. 6 Basic Dot Matrix Wiring
`
`Rnw driver
`
`COlumn! -\
`
`driver "g-l"
`
`Row eleclrodes
`
`Signal lines
`U
`ITnll
`t!lJtlm
`ed:W::id:b:b
`~lilIldlm
`ci:i=W:::£:i:ij:8:J
`Row electrodes
`ttt
`ttt
`
`n-
`
`Signal lines
`
`M'U i---------j
`
`Row driver
`'----~
`
`Fig. 7 Split Type Matrix Wiring
`
`VALEO EX. 1017_006
`
`

`

`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
`
`288.6
`
`REDUCTION OF NUMBER OF SCANNING LINES (cid:173)
`A method of design was developed to reduce the number of
`scanning lines in order to improve the viewing angle and ra·
`sponsiveness without reducing the number of display pixels.
`
`Wiring of LCD Electrodes - There are already various
`methods of electrode wiring to reduce the number of scanning
`lines, such as the split type matrix electrode method and double
`matrix electrode method.
`[10]
`In particular, the split type
`matrix electrode method is adopted in most dot matrix systems.
`In wiring for 32x30 dot matrix display, it normally requires 32
`scanning lines (1/32 duty) as sho.wn in Fig. 6. Fig. 7 shows the
`wiring under the split type matrix electrode method, in which
`case the number of scanning lines can be reduced to a half.
`
`In the Type 2 module, we adopted for the 32x30 dot
`matrix display a combination of the split type matrix electrodes
`and the double matrix electrodes, thus reducing the number of
`scanning lines to one quarter (1/4) of the basic wiring.
`
`A wiring method was developed which would reduce cross~
`ings of the column and row electrode lead wires, nor.mally
`experienced under the double matrix method, and eliminate
`unnecessary light·ups. Such wiring is illustrated in Fig. 8.
`
`Illustrated in Fig.s 9 and 10 are the effects of improved
`response speed and viewing angle enlargement upon reduction
`of scanning lines from 1/32 Duty to 1/8 Duty.
`
`The number of scanning lines can be reduced by designing
`the display using the split
`type or double matrix mathod.
`However, the number of signal lines is increased and the wiring
`gets complicated. Yet,
`it has been ascertained that, as in the
`case of Type 2, a module with comparatively less number of
`signal lines can well accomodate these methods.
`
`-----------:Row driverI
`Signal
`lines
`1)-
`
`l now eleGlrodes l
`
`i Row eleclrodes i
`n
`-..l-.
`Signlll
`lines
`IMPU :f-------jR~Ow~dr~lv~erl
`
`!
`
`!I- .\..-...,,-_"
`
`Coincidence row and
`column electrode dols
`
`Row eleclrodes
`
`Column eleclrodes
`
`\
`
`\
`
`\
`
`\
`
`\
`
`\
`
`\
`
`\
`
`\
`
`V
`/,)..
`.--.-0
`~
`.,?-/
`Decay Time(Td)
`
`\
`
`\
`
`\ ,
`
`0
`-30 -20 -10
`Temperalure reI
`
`10
`
`20
`
`30
`
`0.1
`
`0.01
`
`Fig. 9 Response Time of High Duty Multiplexing
`
`III 1/32 Duly. 1/6 Bias.
`
`a}Basic wiring wilh crossing
`
`bjllew wiring wilhoul Grossing
`
`Fig. 8 Combination of Split Type and Double Matrix Wirings
`Wiring to Avoid Crossing of Lead Wire and Row Electrodes
`
`bll/B Duly. 1/4 BIas
`
`Fig. 10 Equi·contrast distribution curve
`
`VALEO EX. 1017_007
`
`

`

`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
`
`288.7
`
`improved legibility. A concrete example of the driving circuit
`is shown in Fig. 12.
`Featured in this circuit are:
`
`i) Free selection of output timing at each of the output
`terminals of the Column driver lCs.
`ii) Optimized variation of driving voltage by the shifting
`of the duty.
`iii) Stabilized frame frequencies within the range of 30Hz(cid:173)
`120Hz realized by the shifting of the duty.
`
`I±~ ""---Group]
`
`,
`
`"I
`
`Group2
`--Group3
`
`ABC 0 E F GH
`1 'I I
`
`!...L..L..J....LLL.L
`
`Row
`
`234567 8
`
`III ..on
`D ..011
`
`Column
`
`Fig. 11 Scanning Line Grouping Model
`
`Serial data 1
`
`Serial data 2
`
`,- (cid:173),
`
`- - -; Row driver; (cid:173)
`I
`
`Low Duty Ratio Drive of Scanning Lines by Grouping (cid:173)
`We developed display designs as well as a circuit composition
`in which a number of scanning lines would be switched from
`one to another depending on the display comments so as to
`improve the viewing angle dependency and the response speed
`in the display. Some display patterns can create a number of
`scanning lines bearing the same signal.
`By grouping such
`scanning lines, the duty cycle can be reduced without cutting
`down the number of display dots, so as to improve the viewing
`angle characteristics and response speed.
`
`For example, in the case of the display pattern indicated in
`Fig. 11,
`the Iit/non·lit states of rows A-H at columns 2 & 7
`are the same. Therefore, columns 2 & 7 can be regarded as one
`single scanning line. Likewise, columns 3 to 6 can be regarded
`as the same scanning line. Thus the display pattern can be lit at
`1/3 duty.
`
`if, among an [m] number of scanning lines, the
`In general
`numbers of lines expressed as A1, A2,
`.....An can be grouped
`together, the duty can be reduced as low as:
`
`1 / ( m -
`
`(AI + A, + ... + Am-n)
`
`..... (2)
`
`Based on this principle, scanning lines were grouped togeth(cid:173)
`er as much as possible while designing the display pattern in
`order that the display patterns of higher priority (those displayed
`constantly or frequently) are driven at a low duty with an
`
`Programable relerence
`Oscillalor~-~
`
`Exlernal signal input
`---o----Io----J
`---0--<:>-------1
`
`MPU
`
`---0--<)-----1
`
`W LCD
`
`8bit
`bus
`
`Controlleri---::.....----7
`
`Driving vollage data
`
`,;' Shill clock signal
`Oala latch signat
`Synchronous signal
`Liquid cryslal allernaling signal
`
`O/A
`cLon-v-ert-;-e..Jr
`
`Fig. 12 Duty changeover Driving Circuit
`
`to column
`driver
`
`VALEO EX. 1017_008
`
`

`

`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
`
`288.8
`
`The above display system was adopted for the Type 3
`module. This module is normally operated at 1/24 duty. An
`attempt was made to drive it at as Iowa duty as possible after
`determining the scanning lines that can be grouped together
`for each display pattern.
`In the case of the pattern shown in
`Fig. 13,
`the grouping of scanning lines can be calculated as
`m = 24, n = 4, A 1 = 10, A2 = 2, A3 = 2, and A4 = 2, and the
`module can be driven at 1/12 duty. Another display using
`this driving method is shown in photo 7.
`
`is sent
`By this method the same scanning signal
`to all
`members of the group. Therefore, all pixels along the signal
`lines within the group are lit or remain unlit simultaneously,
`which creates a certain limitation on patterns to be displayed.
`However,
`the method is certainly suitable for displays ex(cid:173)
`pressed in bar graphs such as gauges.
`In the case of the module
`with a 1/24 duty drive, the viewing angle ensuring optimum
`legibility by the operator is up to 20 degrees from vertical to
`the module on the right hand and up to 30 degrees on the
`left hand.
`In the case of a 1/12 duty drive this can be increased
`to 30 degrees on the right hand and to 45 degrees on the left
`hand.
`
`In the
`HEATING OF LCD CELL WITH A HEATER -
`module developed in this study, an emphasis has been placed
`on the warning and gauge displays, which need not be switched
`at a high speed as in the case of vehicle speed displays. However,
`at the start of the operation, it will require switching at inter(cid:173)
`vals of about 2 seconds.
`
`Illustrated Fig. 14 is the response speed by multiplexing
`at 1/16 duty drive. To overcome the difficulty in switching
`displays under the temperature of -30°C, a heater was develop(cid:173)
`ed to warm up the LCD cell by more than 10°Cwithin a minute.
`Shown in photo 9 is the appearance of the heater for Type 1
`module.
`
`1/16 DUly. 1/5 Bias
`OolU
`
`Rise Time{Tr)
`
`\
`
`\
`
`\
`
`\
`
`\
`
`\
`
`\
`
`\
`
`\
`
`IJI
`
`\
`
`\
`
`\
`
`Decay Time(Tdl
`
`,
`
`, , , ,
`
`Ii
`
`OOI~O::-1o::10·-!OC-""1O...-cZ"O:-C3"'O-'
`
`Temperalurc (' c)
`
`Fig. 14 Temperature Dependency of Response Characteristics
`
`al Display patlcrn
`
`oj Grouping Dr ~canning lines
`
`Fig. 13 Grouping of Scanning Lines in Type 3 Module
`Driven at 1/12 Duty
`
`Photo 7 Display When Driven at 1/12 Duty
`
`a) 1/12 duty drive
`
`b) 1/24 duty drive
`
`Photo 8 Improvement of Visual Angle Characteristics
`at Low Duty
`
`VALEO EX. 1017_009
`
`

`

`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
`
`288.9
`
`Copper foil
`
`ITO lil:\~rk~~~
`
`'\
`
`Polarizer
`
`Polarizer
`
`Fig. 15 Structure of Heater Terminal
`
`215{D/sqj
`
`300111/,,1
`
`4151 11 /,,1
`
`20
`
`10 •
`
`0
`
`<:;
`
`~
`
`I -10 .
`
`§~
`
`For heater resistance, a layer of
`ITO film is evaporated
`onto the LCD cell surface. Cases of LCD heating using an ITO
`film have been reported already.
`[11]
`
`In the case of this dot matrix module, the LCD cell carries a
`large number of external electrode terminals and uses heat
`seal
`type connectors. Therefore, a special method was devel(cid:173)
`oped by which a piece of copper foil
`is placed on the heater
`terminal and fixed by a clip together with the connector. The
`structure is shown at Fig. 15.
`
`It IS necessary to
`In order to raise the heating capacity,
`thicken the ITO film and lower the resistance. Yet, this will
`also lower the transparency. The sheet resistance was, therefore,
`maintained at the average value of 300n/sq to retain the capa(cid:173)
`bility to raise the temperature at the rate of 1O"C per minute.
`Thus, the switching of displays became possible at intervals of 2
`seconds under the temperature of -30" C. The temperature
`change characteristics are shown in Fig. 16.
`
`a) Prior to attachmenl 01 conneclor
`
`-20 c
`
`-30
`
`!
`
`0
`
`3
`2
`Timelmin)
`
`Fig. 16 Heat Change. Characteristics
`
`CONCLUSION
`in legibility, three types of dot
`Since TNLCD falls short
`matrix modules having. an intermediate number of picture
`elements have been developed with improved legibility.
`
`in driving a multiplexing
`it was important
`In particular,
`TN LCD to expand the viewing angle and design easy to view
`display patterns with a limited number of scanning lines. 1/24
`duty is considered the maximum for a color display module
`for vehicle instruments.
`For a greater display capacity one
`must select a device other than the multiplexing TN LCD. One
`of the candidates for future devices, which is drawing the public
`attention, is the active LCOs.
`
`The active LCDs are already in use for household TVs
`with small picture areas and the manufacturing techniques are
`being established. Many Japanese companies are participating
`in this field. Under the current
`technology it
`is possible to
`produce a unit with a picture area as small as 4 inches. But
`proto-types have been completed for smaller models and are
`expected to be brought into production in a few years.
`
`bl Alter aUachmfnt 01 &onmtor
`
`Photo 9 Appearance of Heater
`
`REFERENCES:
`(1) S.Azumaetal:
`"Development of Toyota Electro Multivision",
`SAE paper 860175, 1986
`
`(2)
`
`"Cadillac Allante" Car and Driver, June 1986
`
`VALEO EX. 1017_010
`
`

`

`Downloaded from SAE International by Ralph Wilhelm, Friday, August 29, 2014
`
`288.10
`
`(3) K. Hiwatari:
`Shuppan Co.
`
`"[See] Technology" 1985-1, Kyoritsu
`
`(4) T. Uchida:
`"Liquid Crystal Multicolor Display"
`ITE Technical Report 22/12 19811PD63-2
`
`(5) T. Uchida. et al.
`"Multicolor LCD with Coiored Layer on Electrodes"
`8th Liquid Crystal Conference in Japan 1982, 3W20
`
`(6) M. Suginoya et al.:
`'Multicolor Graphic LCD with Tri-colored Layers Formed
`by Electrodeposition"
`Japan Display 1983 p206
`
`(7) M. Owa et al:
`"Colored LCD for Automotive Use"
`SAE paper 860176, 1986
`
`(8)
`
`(9)
`
`I. Terada et al.:
`"Improvement of LCD Legibility for Automobiles"
`SAE paper 810171,1981
`
`I. Terada et al.:
`"Dot~matrix LCD for Automotive Application"
`SAE paper 840146, 1984
`
`(10) T. Uchida:
`"Trend of Liquid Crystal Display"
`The Journal of the Institute of Image Electronics Engi(cid:173)
`neers of Japan. vo 1. 12 No.5, 1983
`
`(11) S. Ol<abayashi, et al.:
`'New Automotive Applications for Liquid Crystal Dis(cid:173)
`plays" SAE paper 840144, 1984
`
`VALEO EX. 1017_011
`
`