WO1987007395A1 - Method and device for enhancing the visual contrast in matrix liquid crystal displays - Google Patents

Method and device for enhancing the visual contrast in matrix liquid crystal displays Download PDF

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Publication number
WO1987007395A1
WO1987007395A1 PCT/US1987/001214 US8701214W WO8707395A1 WO 1987007395 A1 WO1987007395 A1 WO 1987007395A1 US 8701214 W US8701214 W US 8701214W WO 8707395 A1 WO8707395 A1 WO 8707395A1
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WO
WIPO (PCT)
Prior art keywords
liquid crystal
pixel lines
illumination
groups
strips
Prior art date
Application number
PCT/US1987/001214
Other languages
French (fr)
Inventor
Dieter Bonnet
Dieter Fischer
Original Assignee
Battelle Development Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Battelle Development Corporation filed Critical Battelle Development Corporation
Publication of WO1987007395A1 publication Critical patent/WO1987007395A1/en

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/133602—Direct backlight
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/3406—Control of illumination source
    • G09G3/342—Control of illumination source using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
    • G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
    • G09G3/34—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source
    • G09G3/36—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters by control of light from an independent source using liquid crystals
    • G09G3/3611—Control of matrices with row and column drivers

Definitions

  • the invention relates to a device for carrying out this method, in which the pixel lines are defined by crossing of two systems of parallel strip electrodes with liquid crystal arranged in between.
  • liquid crystal display systems are increasingly being used which are addressed i n so-called multiplex operation.
  • Addressing i s effected according to the "line-at-a-time" principle i.e. part of the electric potential necessary for achieving maximum orientation of the liquid crystal material is applied to the first of the 200 line electrodes.
  • All the 400 crossed column electrodes receive the picture information potential corresponding to the pixels of the addressed line. Both potentials generate a voltage at the pixel, so that the picture information is visually displayed by the liquid crystal.
  • the first line is written.
  • the next lines are written successively in the same manner.
  • the first line has to be biased in such a manner that it cannot be written identically with the information of the second line. This is effected in such a manner that the voltage applied to the pixels of the first line is about i/3 of the maximum voltage required for switching.
  • Enhanced contrast can be reached in principle by so-called active addressing, i.e. a transistor at each pixel of the display ensures that the voltage at the pixel is kept constant and decay is prevented.
  • Better contrasts are also achieved by bistable, so-called ferroelectric liquid crystals which are still in the development stage.
  • Such arrangements have the drawback that they make the display much more expensive, as the technique for producing 200 x 400 transistors in the required high yield involves very high cost, as the ferroelectric liquid crystals are much more sophisticated than the conventional materials and, in addition, make much higher demands on the accuracy of the assembly technique for the displays, and finally the presentation of half tones involves great difficulties.
  • Liquid crystal displays are often provided with light sources mounted behind them, and viewed in transmission. This illumination can ensure constant brightness and less variable contrast which, however, is still too small.
  • the object of the invention is to provide a method and a device which permit substantial enhancement of the contrast of displays with active, passive or reflective illumination to be achieved without major technical and material expenditure.
  • this problem is solved by successive illumination or exposure to illumination of groups of pixel lines at least during part of the time in which they show maximum contrast, addressing of the illumination or of the exposure to illumination being adapted to the duration and phase of addressing of the individual pixel lines.
  • Advantageous embodiments of the method are described in the Subclaims 2 to 7.
  • the device for implementing the method according to the invention is characterized in that an illuminating system is provided which permits the pixel lines to be illuminated or exposed to illumination successively i n groups, and in that the addressing of the illuminating system is adapted to the duration and phase of addressing of the individual pixel lines in such a manner that the pixel lines can be illuminated or exposed to illumination at least during part of the time in which they show maximum contrast.
  • Particularly preferred embodiments of the device according to the invention are described in Subclaims 9 to 14.
  • the pixel lines are exposed to observation by the human eye in groups of 5 to 50, preferably 10 to 20 lines, exactly at the time when the liquid crystals show maximum orientation, i.e. maximum contrast.
  • a transmissive display with active illumination exposure to viewing is effected by switching-on strip-shaped illuminating means assigned to the said pixel line groups, each of said illuminating means having a duration and phase adapted to the respective line group.
  • a transmissive display with passive illumination exposure to viewing is effected by a liquid crystal system comprising strips and arranged either in front of or behind the matrix liquid crystal display, the individual strips corresponding to the individual line groups, by orienting the liquid crystals of the individual strips with appropriate duration and phase.
  • such a liquid crystal system divided into strips acts like a jalousie or a stepwise moving slot.
  • the light reflected by individual pixel line groups can be admitted - by orientation of the liquid crystals in the individual strips with appropriate duration and phase - by means of a strip-structured liquid crystal system which can be arranged in parallel either in front of or behind the matrix liquid crystal display and also acts like a stepwise moving slot.
  • Fig. 1 shows the transparency of a pixel as a function of time
  • Fig. 2 is an exploded view of a preferred embodiment of the device according to the invention.
  • Fig. 3 is a diagrammatic representation of the adapted addressing of the strip electrodes and the illuminating systems
  • Fig. 4 is an exploded view of another embodiment of the invention.
  • Fig. 1 presents the transparency of a pixel as a function of time.
  • T 0 means the normal transparency corresponding to the color white
  • T min the minimum transparency corresponding to the color black
  • t B the time for the short-time illumination of the pixel according to the invention
  • t F is the total frame time.
  • the pixel Prior to addressing, the pixel shows the normal transparency
  • the pixel After a short time t L , the transparency decreases gradually to the original value T 0 . This means that the pixel shows maximum contrast only during a relatively short time. The human eye, however, sees the information during the total time t F and thus has the impression of a low mean contrast.
  • the pixel is illuminated not during the total time t F , but only during a short time t B .
  • the mean value which is perceived by the human eye becomes effective only by averaging the value of the function T over this time t B .
  • a new mean value is thus obtained, which is substantially higher than the above mean value which is obtained by averaging over the total illumination time t F .
  • Fig. 2 is an exploded view of a matrix liquid crystal display with active illumination.
  • the column electrodes 1 and the line electrodes 2, in the following also called strip electrodes, are arranged normal to each other, so that one pixel is generated at each crossing point.
  • a thin liquid crystal film 3 is arranged between the strip electrodes 1 and 2.
  • the illuminating plate which normally is a coherent film, is divided into strips 4, wherein one strip 4 may comprise a number of pixel lines of the actual display. It is sufficient if the entire display is divided into a relatively small number, e.g. ten, units, in order to achieve a substantial enhancement of contrast.
  • illuminating plate strips 4 are not switched on simultaneously, but successively and in synchronization with the line switching of the display; if the illuminating plate comprises, e.g., ten strips, they are switched on for 1/10 of the frame time of the display. In the case of a total of 200 lines, 20 pixel lines are illuminated simultaneously, and the integration time in Fig. 1 becomes 1/10 of tp. According to the presentation in Fig. 1, t B must be so short that the individual transparency curves T(t) of all the pixels of the liquid crystal display lying in front of an illuminating plate strip 4 essentially show values around the maximum, the values close to T 0 being excluded.
  • the number of illuminating strips 4 can be optimized for achieving the maximum possible contrast. This optimization has to start from the rise and decay times of the liquid crystal and from the frame rate of the display.
  • the illuminating strips 4 can be, for example, strip-structured electroluminescent plates. As can be seen from Fig. 3, addressesing of the illuminating plates 4, which is synchronous with that of the electrodes 1 and 2, can be effected through a controller 5 which is connected with the column driver 6, the line driver 7 and the illuminating strip driver 8.
  • strip-wise illumination of the electrodes 2 of the pixel lines is effected by means of a homogeneous electroluminescent plate 9 or of a different flat homogeneous light source, a second liquid crystal system 10 being arranged in between.
  • the liquid crystal system acts like a stepwise moving slot, which exposes or blocks the illumination in the required width.
  • stripwise illumination of the pixel lines is possible also in the case of a reflectively operated display, if the light reflected by the individual pixel line groups is admitted by a strip-structured liquid crystal system which can be arranged either in front of or behind the display.

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical & Material Sciences (AREA)
  • Mathematical Physics (AREA)
  • Computer Hardware Design (AREA)
  • Theoretical Computer Science (AREA)
  • Liquid Crystal Display Device Control (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
  • Control Of Indicators Other Than Cathode Ray Tubes (AREA)

Abstract

In a matrix liquid crystal display, the visual contrast of the individual image points (= pixels) is enhanced by illuminating or exposing to illumination the pixel lines (2) successively in groups at least during part of the time in which they show maximum contrast. Addressing of the illumination is adapted to the duration and phase of addressing of the individual pixel lines. Strip-wise illumination of the pixel lines can be effected, for example, by using strip-shaped light sources (4) or a second liquid crystal system which can either have a strip structure or be composed of strips and acts like a stepwise moving slot.

Description

METHOD AND DEVICE FOR ENHANCING THE VISUAL CONTRAST IN MATRIX LIQUID CRYSTAL DISPLAYS
Description
The invention relates to a method of enhancing the contrast in matrix liquid crystal displays, which involves short-time and sequential addressing of the image point (= pixel) lines in multiplex operation. In addition, the invention relates to a device for carrying out this method, in which the pixel lines are defined by crossing of two systems of parallel strip electrodes with liquid crystal arranged in between.
To display alphanumeric and graphic data, in particular in computer terminals, such liquid crystal display systems are increasingly being used which are addressed i n so-called multiplex operation. This typically involves generation of 200 x 400 pixels by crossing of two systems of linear strip electrodes consisting of transparent, conductive thin-film material, said electrodes being provided on the two glass plates of the liquid crystal display system, with the liquid crystal arranged in between.
Addressing i s effected according to the "line-at-a-time" principle, i.e. part of the electric potential necessary for achieving maximum orientation of the liquid crystal material is applied to the first of the 200 line electrodes. All the 400 crossed column electrodes receive the picture information potential corresponding to the pixels of the addressed line. Both potentials generate a voltage at the pixel, so that the picture information is visually displayed by the liquid crystal. Thus the first line is written. The next lines are written successively in the same manner. To this end, the first line has to be biased in such a manner that it cannot be written identically with the information of the second line. This is effected in such a manner that the voltage applied to the pixels of the first line is about i/3 of the maximum voltage required for switching. As conventional liquid crystals of the twisted nematic type do not have a significant storage effect, maximum orientation of the liquid crystals decays gradually to the value corresponding to 1/3 voltage. This is effected successively for all the 200 lines of the display, the liquid crystals of each line remaining in maximum orientation only for a limited period of time, and the information has practically disappeared if it is addressed again when the next frame is written. Consequently, the contrast decreases with increasing frame time with respect to the number of lines. This is the critical limiting factor for the line number of a display to be addressed in this easy manner. In the case of more than 100 pixels, the contrast decreases already to values at which the pictures visually appear flat.
Enhanced contrast can be reached in principle by so-called active addressing, i.e. a transistor at each pixel of the display ensures that the voltage at the pixel is kept constant and decay is prevented. Better contrasts are also achieved by bistable, so-called ferroelectric liquid crystals which are still in the development stage. Such arrangements, however, have the drawback that they make the display much more expensive, as the technique for producing 200 x 400 transistors in the required high yield involves very high cost, as the ferroelectric liquid crystals are much more sophisticated than the conventional materials and, in addition, make much higher demands on the accuracy of the assembly technique for the displays, and finally the presentation of half tones involves great difficulties.
Liquid crystal displays are often provided with light sources mounted behind them, and viewed in transmission. This illumination can ensure constant brightness and less variable contrast which, however, is still too small.
The object of the invention is to provide a method and a device which permit substantial enhancement of the contrast of displays with active, passive or reflective illumination to be achieved without major technical and material expenditure.
According to the invention, this problem is solved by successive illumination or exposure to illumination of groups of pixel lines at least during part of the time in which they show maximum contrast, addressing of the illumination or of the exposure to illumination being adapted to the duration and phase of addressing of the individual pixel lines. Advantageous embodiments of the method are described in the Subclaims 2 to 7. The device for implementing the method according to the invention is characterized in that an illuminating system is provided which permits the pixel lines to be illuminated or exposed to illumination successively i n groups, and in that the addressing of the illuminating system is adapted to the duration and phase of addressing of the individual pixel lines in such a manner that the pixel lines can be illuminated or exposed to illumination at least during part of the time in which they show maximum contrast. Particularly preferred embodiments of the device according to the invention are described in Subclaims 9 to 14.
According to the invention, the pixel lines are exposed to observation by the human eye in groups of 5 to 50, preferably 10 to 20 lines, exactly at the time when the liquid crystals show maximum orientation, i.e. maximum contrast. In a transmissive display with active illumination, exposure to viewing is effected by switching-on strip-shaped illuminating means assigned to the said pixel line groups, each of said illuminating means having a duration and phase adapted to the respective line group. In a transmissive display with passive illumination, exposure to viewing is effected by a liquid crystal system comprising strips and arranged either in front of or behind the matrix liquid crystal display, the individual strips corresponding to the individual line groups, by orienting the liquid crystals of the individual strips with appropriate duration and phase. In this case such a liquid crystal system divided into strips acts like a jalousie or a stepwise moving slot. In a reflectively operated display, the light reflected by individual pixel line groups can be admitted - by orientation of the liquid crystals in the individual strips with appropriate duration and phase - by means of a strip-structured liquid crystal system which can be arranged in parallel either in front of or behind the matrix liquid crystal display and also acts like a stepwise moving slot.
The invention is described in more detail on the basis of the schematic drawings.
Fig. 1 shows the transparency of a pixel as a function of time;
Fig. 2 is an exploded view of a preferred embodiment of the device according to the invention;
Fig. 3 is a diagrammatic representation of the adapted addressing of the strip electrodes and the illuminating systems;
Fig. 4 is an exploded view of another embodiment of the invention.
Fig. 1 presents the transparency of a pixel as a function of time. T0 means the normal transparency corresponding to the color white, Tmin the minimum transparency corresponding to the color black, tB the time for the short-time illumination of the pixel according to the invention, and tF is the total frame time. Prior to addressing, the pixel shows the normal transparency
T0. During addressing, the transparency decreases to a value
Tmin. After a short time tL, the transparency decreases gradually to the original value T0. This means that the pixel shows maximum contrast only during a relatively short time. The human eye, however, sees the information during the total time tF and thus has the impression of a low mean contrast. According to method covered by the invention, the pixel is illuminated not during the total time tF, but only during a short time tB. Thus, the mean value which is perceived by the human eye becomes effective only by averaging the value of the function T over this time tB. A new mean value is thus obtained, which is substantially higher than the above mean value which is obtained by averaging over the total illumination time tF.
Fig. 2 is an exploded view of a matrix liquid crystal display with active illumination. The column electrodes 1 and the line electrodes 2, in the following also called strip electrodes, are arranged normal to each other, so that one pixel is generated at each crossing point. A thin liquid crystal film 3 is arranged between the strip electrodes 1 and 2. In order to achieve the effect according to the invention, the illuminating plate which normally is a coherent film, is divided into strips 4, wherein one strip 4 may comprise a number of pixel lines of the actual display. It is sufficient if the entire display is divided into a relatively small number, e.g. ten, units, in order to achieve a substantial enhancement of contrast. These strips 4 are not switched on simultaneously, but successively and in synchronization with the line switching of the display; if the illuminating plate comprises, e.g., ten strips, they are switched on for 1/10 of the frame time of the display. In the case of a total of 200 lines, 20 pixel lines are illuminated simultaneously, and the integration time in Fig. 1 becomes 1/10 of tp. According to the presentation in Fig. 1, tB must be so short that the individual transparency curves T(t) of all the pixels of the liquid crystal display lying in front of an illuminating plate strip 4 essentially show values around the maximum, the values close to T0 being excluded.
The number of illuminating strips 4 can be optimized for achieving the maximum possible contrast. This optimization has to start from the rise and decay times of the liquid crystal and from the frame rate of the display.
The illuminating strips 4 can be, for example, strip-structured electroluminescent plates. As can be seen from Fig. 3, adressing of the illuminating plates 4, which is synchronous with that of the electrodes 1 and 2, can be effected through a controller 5 which is connected with the column driver 6, the line driver 7 and the illuminating strip driver 8.
According to another embodiment, strip-wise illumination of the electrodes 2 of the pixel lines is effected by means of a homogeneous electroluminescent plate 9 or of a different flat homogeneous light source, a second liquid crystal system 10 being arranged in between. In this case the liquid crystal system acts like a stepwise moving slot, which exposes or blocks the illumination in the required width. As mentioned above, stripwise illumination of the pixel lines is possible also in the case of a reflectively operated display, if the light reflected by the individual pixel line groups is admitted by a strip-structured liquid crystal system which can be arranged either in front of or behind the display.

Claims

Patent Claims
1. Method of enhancing the visual contrast in matrix liquid crystal displays, which involves short-term and sequential addressing of the image point (= pixel) lines in multiplex operation, characterized in that the pixel lines are illuminated or exposed to illumination successively in groups at least during part of the time in which they show maximum contrast, addressing of the illumination or of the exposure to illumination being adapted to the duration and phase of addressing of the individual pixel lines.
2. Method as claimed in Claim 1, characterized in that groups of 5 to 50, preferably 10 to 20 pixel lines are illuminated or exposed to illumination.
Method as claimed in Claim 1 or Claim 2, characterized in that each group of pixel lines is illuminated by strip- shaped light sources whose number and width are adapted to the number and width of the groups of pixel lines.
4. Method as claimed in Claim 1 or Claim 2, characterized in that the groups of pixel lines are exposed to illumination by means of a liquid crystal system which is arranged in front of or behind the matrix liquid crystal display and acts like a stepwise moving slot, the number and width of the strips of the liquid crystal system being adapted to the number and width of the groups of pixel lines.
Method as claimed in Claim 4, characterized in that the strips of the liquid crystal system are achieved by appropriate structuring.
Method as claimed in Claim 4, characterized in that the liquid-crystal system is divided into strips.
7. Method as claimed in any of the Claims 4 to 6, characterized in that the liquid crystal system is arranged between the matrix liquid crystal display and a reflective film.
8. Device for enhancing the visual contrast in matrix liquid crystal displays, in which pixel lines are defined by crossing of two systems of parallel strip electrodes with liquid crystal arranged in between, wherein short-term and sequential addressing of the pixel lines in multiplex operation is possible, for carrying out the method according any of the Claims 1 to 7, characterized in that an illuminating system (4, 9, 10) is provided which permits the pixel lines to be illuminated or exposed to illumination successively in groups, and in that the addressing of the illuminating system (4, 10) is adapted to duration and phase of addressing of the individual pixel lines in such a manner that the pixel lines can be illuminated cr exposed to illumination at least during part of the time in which they show maximum contrast.
9. Device as claimed in Claim 8, characterized in that each group of pixel lines covers 5 to 50, preferably 10 to 20 pixel lines.
10. Device as claimed in Claim 8 or Claim 9, characterized in that an illuminating plate (4) divided into strips, preferably an electroluminescent plate, is provided as illuminating system, the number and width of the individual strips (4) corresponding to the number and width of the individual groups of pixel lines.
11. Device as claimed in Claim 8 or Claim 9, characterized in that the illuminating system consists of a liquid crystal system (10) which is arranged in front of or behind the matrix liquid crystal display and acts like a stepwise moving slot, the number and width of the strips of the liquid crystal system (10) being adapted to the number and width of the pixel line groups.
12. Device as claimed in Claim 11, characterized in that the liquid crystal system (10) has a strip structure.
13. Device as claimed in Claim 11, characterized in that the liquid crystal system (10) is divided into strips.
14. Device as claimed in any of the Claims 11 to 13, characterized in that the liquid crystal system (10) is arranged between the matrix liquid crystal display and a reflective film.
PCT/US1987/001214 1986-05-20 1987-05-20 Method and device for enhancing the visual contrast in matrix liquid crystal displays WO1987007395A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DEP3616940.4 1986-05-20
DE19863616940 DE3616940A1 (en) 1986-05-20 1986-05-20 METHOD AND DEVICE FOR INCREASING THE VISUAL CONTRAST IN MATRIX LIQUID CRYSTAL SCREENS

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WO1987007395A1 true WO1987007395A1 (en) 1987-12-03

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Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19540363C2 (en) * 1995-10-30 1997-10-16 Univ Schiller Jena Flat screen
JP3780952B2 (en) 2002-01-31 2006-05-31 株式会社豊田自動織機 Liquid crystal display

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3869195A (en) * 1973-07-02 1975-03-04 Itek Corp Liquid crystal display containing segmented source of back-lighting
DE2655866A1 (en) * 1975-12-10 1977-06-23 Marconi Co Ltd PLAYBACK ARRANGEMENT
US4139272A (en) * 1976-05-20 1979-02-13 Ebauches S.A. Electro-optic passive display device
US4364039A (en) * 1980-07-25 1982-12-14 Texas Instruments Incorporated Stacked electro-optic display
EP0131873A1 (en) * 1983-07-08 1985-01-23 Hitachi, Ltd. Driving method of a liquid crystal switch for a printer, and printer therefor

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2237785C3 (en) * 1972-08-01 1982-01-14 Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt Electrical display device with point-by-point display based on the matrix principle
CH609521B (en) * 1976-05-13 Ebauches Sa PASSIVE ELECTRO-OPTICAL DISPLAY DEVICE.
DE3037224A1 (en) * 1980-10-02 1982-04-29 Philips Patentverwaltung Gmbh, 2000 Hamburg Electro-optical display - uses e.c.l. cell behind l.c.d. for illumination

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3869195A (en) * 1973-07-02 1975-03-04 Itek Corp Liquid crystal display containing segmented source of back-lighting
DE2655866A1 (en) * 1975-12-10 1977-06-23 Marconi Co Ltd PLAYBACK ARRANGEMENT
US4139272A (en) * 1976-05-20 1979-02-13 Ebauches S.A. Electro-optic passive display device
US4364039A (en) * 1980-07-25 1982-12-14 Texas Instruments Incorporated Stacked electro-optic display
EP0131873A1 (en) * 1983-07-08 1985-01-23 Hitachi, Ltd. Driving method of a liquid crystal switch for a printer, and printer therefor

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DE3616940A1 (en) 1987-11-26
DE3616940C2 (en) 1988-11-03
JPH01500302A (en) 1989-02-02

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