EP1259852A2 - Dispositif de filtrage electro-optique actif et procede pour faire fonctionner ce dernier - Google Patents

Dispositif de filtrage electro-optique actif et procede pour faire fonctionner ce dernier

Info

Publication number
EP1259852A2
EP1259852A2 EP00901013A EP00901013A EP1259852A2 EP 1259852 A2 EP1259852 A2 EP 1259852A2 EP 00901013 A EP00901013 A EP 00901013A EP 00901013 A EP00901013 A EP 00901013A EP 1259852 A2 EP1259852 A2 EP 1259852A2
Authority
EP
European Patent Office
Prior art keywords
optical filter
active
filter element
liquid crystal
operating
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP00901013A
Other languages
German (de)
English (en)
Inventor
Leo Keller
Emil Ackermann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Optrel AG
Original Assignee
Optrel AG
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 Optrel AG filed Critical Optrel AG
Publication of EP1259852A2 publication Critical patent/EP1259852A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F9/00—Methods or devices for treatment of the eyes; Devices for putting in contact-lenses; Devices to correct squinting; Apparatus to guide the blind; Protective devices for the eyes, carried on the body or in the hand
    • A61F9/04—Eye-masks ; Devices to be worn on the face, not intended for looking through; Eye-pads for sunbathing
    • A61F9/06—Masks, shields or hoods for welders
    • A61F9/065—Masks, shields or hoods for welders use of particular optical filters
    • A61F9/067—Masks, shields or hoods for welders use of particular optical filters with variable transmission
    • 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
    • G02F1/13306—Circuit arrangements or driving methods for the control of single liquid crystal cells
    • 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
    • G02F1/13306—Circuit arrangements or driving methods for the control of single liquid crystal cells
    • G02F1/13318—Circuits comprising a photodetector
    • 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
    • G09G3/04—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions
    • G09G3/16—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions by control of light from an independent source
    • G09G3/18—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of a single character by selection from a plurality of characters, or by composing the character by combination of individual elements, e.g. segments using a combination of such display devices for composing words, rows or the like, in a frame with fixed character positions by control of light from an independent source using liquid crystals
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S323/00—Electricity: power supply or regulation systems
    • Y10S323/906—Solar cell systems

Definitions

  • the invention relates to an active electro-optical filter device and a method for its operation according to the preambles of the independent claims.
  • the filter device is particularly suitable as an anti-glare device for use in
  • Filter devices of this type are e.g. B. from the publications WO 97/15254, US 5,315,099 or EP-0 550 384 known.
  • they typically contain at least one liquid crystal cell (liquid crystal cell, LC cell), which more or less blocks the passage of light as soon as a light sensor is subjected to a light intensity that exceeds a predetermined threshold.
  • liquid crystal cell liquid crystal cell, LC cell
  • the use of such filter devices is diverse; a typical example is the use as a viewing window for welding masks, helmets and glasses.
  • the filter devices described in the cited documents consist of active filter elements, for example of nematic liquid crystal elements preferably rotating by 0-90 °, which are located between two crossed polarizers. They are operated with an operating voltage that is several times above the Freedericksz threshold.
  • the Freedericksz threshold is the control voltage of a liquid crystal cell at which a first optical activity of the cell can be observed.
  • the choice of a higher operating voltage is in the above publications with a reduction in the stray light, a reduced temperature dependence of the electro-optical effect and the generation of an optical transmission of less than 1%.
  • the control frequency of such active filter elements is between 0 and 32 Hz for reasons of low power consumption.
  • the main reason for the limited availability of electrical supply power is the operation of the filter elements with current from backup batteries and solar cells. While continuous DC voltage operation still permanently damages liquid crystal cells due to electrolysis and ion migration or severely impairs their optical performance, significant improvements have been achieved through continuous improvement of the insulating layers, through reduction of impurities and through the achievement of higher conductivity values of the liquid crystal substances used.
  • the selection of a drive frequency which is as small as possible is aimed at because the drive frequency is linearly input into the power consumption of a liquid crystal cell. However, it would be desirable to further reduce power consumption.
  • N 1 - (7/3) logT (1)
  • the optical quality is greatly impaired by stray light.
  • the scattering of light on an LC cell has various causes: among other things, particles enclosed in the LC cell, different layer thicknesses, scratches, edges and / or spacers (so-called spacers) between the glass plates enclosing the liquid crystal.
  • the object is achieved by the filter device and the method as defined in the independent patent claims.
  • the electro-optical filter device is preferably equipped with a special control circuit.
  • the drive circuit according to the invention contains a switch which short-circuits the liquid crystal cell for a certain time in each half period. Neither a continuous toggle switch nor a non-stop changing control voltage is therefore selected.
  • the control according to the invention differs from the prior art by the insertion of an active edge and a control method, which rather corresponds to a pulse width modulation instead of a continuous frequency.
  • the frame frequency of the control pulses is in the range from 0.01 to 1 Hz. The energy expenditure is halved with this method compared to the prior art, which means enormous progress.
  • the present invention uses an operating voltage that is clearly defined. On the one hand, it lies several times above the Freedericksz threshold in order to achieve the optical density prescribed in the product standard EN 169. In addition, the operating voltage is determined in such a way that it lies at the voltage at which the light scattered by the LCD display is minimal.
  • operating voltages set in this way are in the range of 10 to 50 volts.
  • the adjustment of the residual transmission can be achieved, for example, with a small offset in the polarizer orientation or with an adjustment of the polarization efficiency.
  • the influence of scattered light from the measuring device ( ⁇ 2R ) was neglected in the discussion above.
  • Show: 1 is a filter device designed as a glare protection device
  • Fig. 4 shows the reduced luminance coefficient as a function of the operating voltage.
  • FIG. 1 shows a filter device according to the invention, designed as a glare protection device. It contains at least one active optical filter element 1 with a liquid crystal.
  • the liquid crystal is designed according to one of the following technologies: TN technology, STN technology, dichroic technology, ferroelectric technology or ⁇ -mode LCD technology.
  • the filter device contains electronic means 2 for controlling the active filter element 1.
  • At least one light sensor 4 interacts with the electronic means 2.
  • the electronic means 2 are supplied, for example, with output signals from the light sensors 4 for the purpose of controlling or regulating the operating voltage of the filter element.
  • Power supply means 5 are provided for the electronic means 2, the optical filter element 1 and possibly the light sensors 4. These can, for example, be designed as solar cells.
  • the liquid crystal is represented on the equivalent circuit diagram of FIG. 2 by a resistor R L C and a capacitance CLC. Other resistors in the circuit are in resistors Rsi and Rs2 summarized.
  • An AC voltage source 21 supplies an AC voltage U 1 with a frame frequency f of typically 0.01 to 1 Hz.
  • the control circuit according to the invention includes a switch S 1, which short-circuits the liquid crystal cell for a specific time t s . This results in the complete discharge of the capacitor CLC. The energy expenditure for the counter-polar charge of the capacitor C L C is thus halved with this control circuit compared to the prior art.
  • FIG. 3 shows the operating voltage U (t) supplied by the control circuit according to the invention as a function of time t.
  • . Is first generated during a first time interval t + applied to the liquid crystal cell 1.
  • the liquid crystal cell 1 short-circuited during a second time interval tsi.
  • active edges 31, 32 are inserted into the course of the operating voltage U (t).
  • This control method according to the invention most closely corresponds to pulse width modulation.
  • the time intervals in FIG. 3 are not drawn to scale for reasons of clarity: during the first time interval t + and the third time interval L have typical lengths of 0.5 to 50 s, typical lengths of the second time interval tsi and the fourth time interval ts 2 are in the range from microseconds to milliseconds.
  • the short-circuit times tsi, ts 2 are therefore shorter than the activation times t +, t by factors in the order of 10 3 to 10 7 .
  • FIG. 4 shows a typical dependency of the reduced luminance coefficient / * (U) (cf. equation (2)) as a function of the operating voltage U.
  • the analysis of the Scattering phenomena on a liquid crystal cell 1 is important for understanding the invention.
  • the causes of light scattering are, for example, particles enclosed in the liquid crystal cell 1, different layer thicknesses, scratches, edges and / or spacers between two glass plates enclosing the liquid crystal.
  • a static part / * s and a dynamic part l * _ can be distinguished.
  • the static stray light fraction / * s can be reduced with suitable technical measures to such an extent that the user of an active anti-glare filter does not have to accept any loss in image quality (stray light class 1, in accordance with European standard EN 379).
  • the situation is very different for the dynamic, voltage-dependent scattered light component l * d .
  • a local orientation disturbance forms around the above-mentioned scattered light centers when an operating voltage U is applied.
  • the foreign body causing the scattered light center - or the edge - disturbs the homogeneous, chiral orientation of the liquid crystal molecules.
  • These local orientation disorders are largely responsible for the voltage-dependent scattered light component l * _. With a higher operating voltage U, the liquid crystal molecules are aligned more and more parallel to the field strength vector and the local orientation disorder is thus eliminated.
  • the reduced luminance coefficient / * shown in FIG. 4 is essentially the ratio of the scattered light flux ⁇ i R and the unscattered light flux ( ⁇ .
  • the curve / * (U) distinguishes three areas.
  • the operating voltage U U LC SO is selected so that the following conditions are met:
  • the operating voltage ULC is determined from this as follows.
  • Condition a) defines a band on the U axis in which the operating voltage U LC must be in order to achieve the required transmission.
  • the operating voltage U L C is then clearly determined in this band according to condition b), so that / * becomes minimal.
  • the working point U LC is in the third area III of the curve / * (U).
  • the transmission can be adjusted by slightly rotating the polarizers or by adjusting the polarizer efficiency.

Landscapes

  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Chemical & Material Sciences (AREA)
  • Optics & Photonics (AREA)
  • Mathematical Physics (AREA)
  • Vascular Medicine (AREA)
  • Biomedical Technology (AREA)
  • Public Health (AREA)
  • General Health & Medical Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Veterinary Medicine (AREA)
  • Ophthalmology & Optometry (AREA)
  • Computer Hardware Design (AREA)
  • Theoretical Computer Science (AREA)
  • Liquid Crystal (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
  • Liquid Crystal Display Device Control (AREA)

Abstract

L'invention concerne un dispositif de filtrage électro-optique actif, s'utilisant en particulier comme dispositif anti-éblouissement pour des masques, casques et lunettes de soudeur. Ce dispositif comprend, de façon connue en soi, un filtre photoprotecteur comportant au moins un élément de filtrage optique actif et un système électronique pour commander ledit élément de filtrage actif, ainsi qu'un photodétecteur coopérant avec le système électronique, et une alimentation électrique, notamment une cellule solaire, pour le système électronique et l'élément de filtrage actif. Le circuit de commande pour l'élément de filtrage actif est conçu de sorte que, dans la plage de la fréquence de trame (1/T) comprise entre 0,01 et 1 Hz, le condensateur de charge est entièrement déchargé pendant un court instant, ce qui a pour effet de diviser par deux la puissance absorbée par rapport aux circuits connus. Parallèlement, la tension de service (U) est située dans une plage qui est fixée de manière quantitative et dans laquelle la proportion de lumière diffusée de l'affichage à cristaux liquides utilisé est minimale.
EP00901013A 1999-03-11 2000-01-28 Dispositif de filtrage electro-optique actif et procede pour faire fonctionner ce dernier Withdrawn EP1259852A2 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
CH00458/99A CH694384A5 (de) 1999-03-11 1999-03-11 Aktive elektrooptische Filtereinrichtung und Verfahren zu ihrem Betrieb.
CH45899 1999-03-11
PCT/CH2000/000040 WO2000054097A2 (fr) 1999-03-11 2000-01-28 Dispositif de filtrage electro-optique actif et procede pour faire fonctionner ce dernier

Publications (1)

Publication Number Publication Date
EP1259852A2 true EP1259852A2 (fr) 2002-11-27

Family

ID=4187481

Family Applications (1)

Application Number Title Priority Date Filing Date
EP00901013A Withdrawn EP1259852A2 (fr) 1999-03-11 2000-01-28 Dispositif de filtrage electro-optique actif et procede pour faire fonctionner ce dernier

Country Status (6)

Country Link
EP (1) EP1259852A2 (fr)
KR (1) KR20020007319A (fr)
CN (1) CN1559021A (fr)
CH (1) CH694384A5 (fr)
TW (1) TW527499B (fr)
WO (1) WO2000054097A2 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100347593C (zh) * 2003-12-27 2007-11-07 Lg.菲利浦Lcd株式会社 液晶显示器件的制造方法
EP2799046A1 (fr) 2013-04-30 2014-11-05 Optrel Ag Dispositif et méthode pour la protection de l'éblouissement

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8264265B2 (en) 2010-09-30 2012-09-11 Kimberly-Clark Worldwide, Inc. Automatic darkening filter (ADF) eye protection device with improved drive circuitry

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5731148B2 (fr) * 1973-05-15 1982-07-02
US4279474A (en) * 1980-03-25 1981-07-21 Belgorod Barry M Spectacle lens having continuously variable controlled density and fast response time
CH687909A5 (de) * 1991-12-31 1997-03-27 Xelux Holding Ag Verfahren zum Betrieb einer Blendschutzvorrichtung.
SE509569C2 (sv) * 1995-10-26 1999-02-08 Hoernell International Ab Vätskekristallslutarkonstruktion

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0054097A2 *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN100347593C (zh) * 2003-12-27 2007-11-07 Lg.菲利浦Lcd株式会社 液晶显示器件的制造方法
EP2799046A1 (fr) 2013-04-30 2014-11-05 Optrel Ag Dispositif et méthode pour la protection de l'éblouissement

Also Published As

Publication number Publication date
WO2000054097A2 (fr) 2000-09-14
CH694384A5 (de) 2004-12-15
KR20020007319A (ko) 2002-01-26
CN1559021A (zh) 2004-12-29
WO2000054097A3 (fr) 2002-09-26
TW527499B (en) 2003-04-11
WO2000054097A8 (fr) 2003-01-03

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