EP0604448B1 - Method of addressing a matrix-array type liquid crystal cell - Google Patents
Method of addressing a matrix-array type liquid crystal cell Download PDFInfo
- Publication number
- EP0604448B1 EP0604448B1 EP92916450A EP92916450A EP0604448B1 EP 0604448 B1 EP0604448 B1 EP 0604448B1 EP 92916450 A EP92916450 A EP 92916450A EP 92916450 A EP92916450 A EP 92916450A EP 0604448 B1 EP0604448 B1 EP 0604448B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- blanking
- pulses
- select
- pulse
- addressing
- 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.)
- Expired - Lifetime
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Classifications
-
- 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
- G09G3/3622—Control of matrices with row and column drivers using a passive matrix
- G09G3/3629—Control of matrices with row and column drivers using a passive matrix using liquid crystals having memory effects, e.g. ferroelectric liquid crystals
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- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2310/00—Command of the display device
- G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
- G09G2310/0202—Addressing of scan or signal lines
- G09G2310/0205—Simultaneous scanning of several lines in flat panels
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2310/00—Command of the display device
- G09G2310/06—Details of flat display driving waveforms
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2310/00—Command of the display device
- G09G2310/06—Details of flat display driving waveforms
- G09G2310/061—Details of flat display driving waveforms for resetting or blanking
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2310/00—Command of the display device
- G09G2310/06—Details of flat display driving waveforms
- G09G2310/065—Waveforms comprising zero voltage phase or pause
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2320/00—Control of display operating conditions
- G09G2320/02—Improving the quality of display appearance
- G09G2320/0247—Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
Definitions
- the present invention relates to a method for addressing a matrix-type liquid crystal cell and the method has particular, although not exclusive, relevance to such cells as are employed within visual displays and the like.
- One known method of addressing a matrix-array type liquid crystal cell is that disclosed in UK Patent Number GB 2,173,336B.
- the cell is treated as a matrix of orthogonal row and column electrodes. Waveforms are applied to both the rows and columns in order to selectively switch the individual elements into either the dark (non-light transmitting) state, or the light transmitting state.
- To the column electrodes may be applied two types of data waveform: "on” or "unchanged”. Synchronised to these waveforms are those waveforms which are applied to the row electrodes, these are termed “select”, “non-select” and "blank”. At any one time, only one row electrode has the “select” waveform applied to it, and at least one other row electrode has the "blank” waveform applied to it. All the remaining row electrodes have the "non-select" waveform applied thereto.
- a row electrode Contemporaneously with the application of the data waveform, a row electrode has the blank waveform applied to it. It will be apparent to those skilled in the art that with any such system it is a requirement to maintain dc compensation, or charge balancing, that is both the "on" and “unchanged” data waveforms must have no dc component.
- the system exemplified in GB 2,173,336B suffers from the shortcomings that the response time of the liquid crystal material is slowed down if the blanking waveform is applied to a row electrode only shortly before the application of the select waveform to that same row electrode. This is because the magnitude of the blanking waveform is greater than that required to set the liquid crystal material into its dark state and therefore a degree of relaxation must ensue before the electrode addressing activity may occur.
- the disclosure in GB 2,173,336B does indicate generally that the duration and amplitude of blanking pulses can be concomitantly changed to suit specific requirements, but there is no indication that the expedient could have value in addressing the shortcomings identified above.
- the solution advocated involves the introduction of one or more gaps into the data pulse waveforms.
- the introduction of gaps into the data pulse waveforms is undesirable because (being of extremely short duration) they require the switching circuits and associated components to have extremely high reaction speed.
- DE 3,501,982 describes another addressing technique, in which blanking pulses are applied simultaneously to both sets of electrodes; each individual blanking pulse being of smaller amplitude than the strobing (or select) pulse, but the combined effect of the two synchronised blanking pulses being such as to create, at the pixels, a voltage which exceeds that of the strobing (select) pulse.
- a method of addressing a matrix-array type liquid crystal cell including ferroelectric liquid crystal material comprising a plurality of pixels which are defined by areas of overlap between members of a first set of electrodes on one side of the material and members of a second set of electrodes, oriented orthogonal to the first set, on the other side of the material; in which method the pixels of the array are addressed on a line-by-line basis after blanking, wherein unipolar blanking pulses are applied exclusively to the members of the first set of electrodes to effect blanking and wherein for selective addressing of the pixels, unipolar select pulses are applied serially and exclusively to the members of the first set of electrodes while charge-balanced bipolar data pulses are applied exclusively and in parallel to the members of the second set, the positive going parts of the data pulses being synchronised with the select pulses for one data significance and the negative going parts of the data pulses being synchronised with the select pulses for the other data significance, wherein the polarities
- the present invention provides a method for addressing a matrix-array type liquid crystal cell whereby the potential for the response time of the liquid crystal material being slowed down is reduced by providing a blanking pulse whose amplitude and duration may be modified as desired, within working limits.
- a matrix-array type liquid crystal cell shown generally as 2 comprises an array of overlapping orthogonal row 4 and column 6 electrodes between which is disposed liquid crystal material (not shown).
- the data signals which may be applied to the column electrodes 6 are the "unchanged” waveform 8 and the "on” waveform 10.
- the row electrode 4 waveforms, which are applied synchronous with the column electrode waveforms 8,10 are the "select” 12, "non-select” 14 and "blank” 16 waveforms.
- Figures 2(a), (b), (c) and (d) illustrate the resultant waveforms at the intersections of row and column electrodes 4,6 as a result of combining the selected waveforms applied thereto.
- the method of addressing one particular pixel 3 within cell 2, which is defined by an area of overlap between a row electrode 4 and a column electrode 6 is as follows: Before any addressing of the cell 2 with display data may take place, the row 4 of which the one particular pixel 3 forms a part must first be set into the dark state state. This is achieved by applying a blanking waveform 16 thereto. This is necessary to ensure that the whole row 4 is set into a predetermined state from which display data addressing may take place.
- the desired display data waveform 8 or 10, say 8, is applied to the desired column electrode 6 which intersects or overlies pixel 3. Simultaneously, the corresponding electrode 4 which overlies pixel 3 has applied thereto the select waveform 12.
- the select waveform 12 By reference particularly to figure 2(a) it will be seen that the combination of unchanged waveform 8 and select waveform 12 at pixel 3 creates a specific combined waveform. Similarly, if the on waveform 10 had been selected instead of the unchanged waveform 8, then the resulting waveform at pixel 3 would have been that which is shown in figure 2(b).
- the electrode for the next row which it is desired to address will receive blanking waveform 16 ready for addressing, as above.
- V d is the voltage of the data waveform 8,10 and T is the time duration of a waveform having this voltage amplitude.
- V s is the amplitude of the select waveform 12;
- V b is the amplitude of the blanking waveform 16.
- the areas defined by the select 12 and blanking pulses 16 are equal, although the area defined by the select pulse may never be less than that of the preceding blanking pulse.
- the blanking pulse 16 has an implitude V s /n and duration mT as compared with select pulse 12 which has amplitude V s and duration T.
- Figure 5 illustrates the switching characteristics of the cell 2 by plotting the voltage applied thereto against the time for which this voltage is applied. It is known to those skilled in the art that generally, the magnitude of the blanking pulse 16 is greater than is actually required in order to set each pixel 3 into the "dark" state. Because of this, then some relaxation period immediately subsequent to the application of the blanking pulse will be necessary before addressing takes place. Thus, by reducing the amplitude of the blanking waveform 16 in accordance with the present invention, yet still remaining within the switching boundary of figure 5, the need for a relaxation period may be obviated.
- n and m may be used, although integer values have been found convenient. There is no necessity for n and m to be equal but m must be greater than or equal to n.
- n and m are chosen to be equal, it is preferable that values of greater than or equal to 2 are chosen; this is because a value of less than 2 would lead to the blanking waveform 16 amplitude and duration being such that it approaches that of Figure 1(a), which causes no switching. In this case the blanking waveform 16 would be ineffective.
- FIG 4 an illustration is given of the general waveform which appears at pixel 3 when it is addressed with a blanking pulse 16 in accordance with the present invention.
- This figure illustrates the requirement V s /n>V d , because it can be seen that if the amplitude of the blanking pulse 16, V s /n falls below V d , then there will be some time during the blanking period when the voltage changes polarity, and this change in polarity may promote switching in the opposite direction away from the desired blank (or dark) state. Hence the limit V s /n > V d .
- the amplitude of the blanking pulse 16 must be greater than or equal to that of the data pulses 8,10. This is so that during application of the blanking pulse 16 there is no excursion of the difference between blanking pulse 16 and either data pulse 8 or 10 to a polarity opposite that of blanking pulse 16.
- the present invention provides a method of addressing a matrix-array type liquid crystal cell having a modified blanking waveform whereby the response time of the liquid is maintained.
- the number of lines of pixels between the application of the blanking pulse 16 and the select pulse 12 may be reduced to 8 or less.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Physics & Mathematics (AREA)
- Computer Hardware Design (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Liquid Crystal Display Device Control (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
Abstract
Description
Claims (7)
- A method of addressing a matrix-array type liquid crystal cell (2) including ferro electric liquid crystal material, the cell comprising a plurality of pixels (3) which are defined by areas of overlap between members of a first (4) set of electrodes on one side of the material and members of a second set (6) of electrodes, oriented orthogonal to the first set, on the other side of the material; in which method the pixels of the array are addressed on a line-by-line basis after blanking, wherein unipolar blanking pulses (16) are applied exclusively to the members of the first set (4) of electrodes to effect blanking and wherein for selective addressing of the pixels, unipolar select pulses (12) are applied serially and exclusively to the members of the first set (4) of electrodes while charge-balanced bipolar data pulses (8, 10) are applied exclusively and in parallel to the members of the second set, (6) the positive going parts of the data pulses being synchronised with the select pulses for one data significance and the negative going parts of the data pulses (8, 10) being synchronised with the select pulses (12) for the other data significance, wherein the polarities of the select (12) and blanking (16) pulses are opposite and invariable and characterised in that reductions in the response time of said liquid crystal material to said selective addressing of the pixels (3) when blanking pulses (16) and select pulses (12) are applied temporally adjacent one another are mitigated by the use of blanking pulses (16) of magnitude V s/n and duration mT, where Vs is the select pulse (12) voltage, T is the duration of the select pulse (12) and n and m are arbitrary values where m is greater than or equal to n such that the amplitude of any given blanking pulse (16) is less than that of any given select pulse (12).
- A method according to claim 1 wherein n and m are equal values such that charge balancing is maintained for the individual members of the first set (4) of electrodes by the areas defined by the select (12) and blanking (16) pulses being equal.
- A method according to claim 1 or claim 2 wherein n and m are integer values.
- A method according to claim 3 where n and m have value 2.
- A method according to claim 1 wherein m is greater than n.
- A method according to claim 5 wherein n and m are integer values.
- A method according to any one of the proceeding claims wherein, for any given line of pixels (3) within the array, the blanking pulse (16) is applied thereto prior to the application of the select pulse (12), the number of lines between the blanking (16) and select (12) pulses being less than or equal to 8.
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9120210 | 1991-09-21 | ||
GB919120210A GB9120210D0 (en) | 1991-09-21 | 1991-09-21 | Method of addressing a matrix-array type liquid crystal cell |
PCT/GB1992/001464 WO1993006586A1 (en) | 1991-09-21 | 1992-08-07 | Method of addressing a matrix-array type liquid crystal cell |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0604448A1 EP0604448A1 (en) | 1994-07-06 |
EP0604448B1 true EP0604448B1 (en) | 1998-01-28 |
Family
ID=10701816
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP92916450A Expired - Lifetime EP0604448B1 (en) | 1991-09-21 | 1992-08-07 | Method of addressing a matrix-array type liquid crystal cell |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP0604448B1 (en) |
JP (1) | JP3122137B2 (en) |
CA (1) | CA2119459C (en) |
DE (1) | DE69224292T2 (en) |
GB (1) | GB9120210D0 (en) |
WO (1) | WO1993006586A1 (en) |
Families Citing this family (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH0772455A (en) * | 1993-09-01 | 1995-03-17 | Sony Corp | Active matrix liquid crystal display device |
JP4267073B2 (en) | 1996-10-09 | 2009-05-27 | 日本ゼオン株式会社 | Solution in which norbornene polymer composition is dissolved in a solvent |
JP4187269B2 (en) | 1996-10-29 | 2008-11-26 | 日本ゼオン株式会社 | Crosslinkable polymer composition |
US6613855B1 (en) | 1997-04-09 | 2003-09-02 | Sanyo Chemical Industries, Ltd. | Polymerizable resin, and cured resins, insulators, components of electrical appliances, and electrical appliances made by using the same |
JP3890738B2 (en) | 1998-04-09 | 2007-03-07 | 日本ゼオン株式会社 | Resin composition containing soft polymer |
JP6078215B2 (en) * | 2013-06-29 | 2017-02-08 | 義夫 遠山 | Batting practice device |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2558606B1 (en) * | 1984-01-23 | 1993-11-05 | Canon Kk | METHOD FOR CONTROLLING AN OPTICAL MODULATION DEVICE AND OPTICAL MODULATION DEVICE FOR IMPLEMENTING IT |
GB2173336B (en) * | 1985-04-03 | 1988-04-27 | Stc Plc | Addressing liquid crystal cells |
-
1991
- 1991-09-21 GB GB919120210A patent/GB9120210D0/en active Pending
-
1992
- 1992-08-07 JP JP05505857A patent/JP3122137B2/en not_active Expired - Fee Related
- 1992-08-07 CA CA002119459A patent/CA2119459C/en not_active Expired - Fee Related
- 1992-08-07 EP EP92916450A patent/EP0604448B1/en not_active Expired - Lifetime
- 1992-08-07 DE DE69224292T patent/DE69224292T2/en not_active Expired - Fee Related
- 1992-08-07 WO PCT/GB1992/001464 patent/WO1993006586A1/en active IP Right Grant
Also Published As
Publication number | Publication date |
---|---|
JP3122137B2 (en) | 2001-01-09 |
DE69224292T2 (en) | 1998-07-23 |
JPH06511095A (en) | 1994-12-08 |
EP0604448A1 (en) | 1994-07-06 |
CA2119459A1 (en) | 1993-04-01 |
GB9120210D0 (en) | 1991-11-06 |
CA2119459C (en) | 2002-11-26 |
WO1993006586A1 (en) | 1993-04-01 |
DE69224292D1 (en) | 1998-03-05 |
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