CN1536407A - High-brightness high-reflection negative cholesteric phase liquid crystal display utilizing novel blazing reflector - Google Patents
High-brightness high-reflection negative cholesteric phase liquid crystal display utilizing novel blazing reflector Download PDFInfo
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- CN1536407A CN1536407A CNA031092918A CN03109291A CN1536407A CN 1536407 A CN1536407 A CN 1536407A CN A031092918 A CNA031092918 A CN A031092918A CN 03109291 A CN03109291 A CN 03109291A CN 1536407 A CN1536407 A CN 1536407A
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Abstract
The invention relates to a reflecting, high-brightness, high-quality, all-color, negative cholesteryl- phase LCD, specially a florid reflection sheet which can select light reflection, designed by optical total reflection principle. It can locate the display in the focal-conic texture to make the forward scattered reflex become backward scattered light, enhancing the reflection brightness of the display, here, it can limit most transmitted light located in the plane texture in it, enhancing the contrast ratio of the display. Its backward scattered light is milk-white, and it prepares tricolor filter film on the basal sheet of the negative cholesteryl-phase LCD, able to obtain high-quality all-color displaying. The focal-conic and plane textures are both in a stable state, and the display image can be reactively stored at zero driving voltage. In addition, when displaying, it need not use internal light source, saving a large amount of electric energy.
Description
Technical field:
The present invention relates to a kind of reflective high brightness, high-quality full color negativity cholesteric liquid crystal displays, particularly relate to a kind of reflector plate of showing off that utilizes the optical total-reflection principle design with the reflection of selection incident light.
Background technology:
Now, the electronic equipment of carrying, as electronic reader (e-Book), personal data processor (PDA), individual satellite locator (GPS), mobile phone and removable computer (Tablet PC), new product emerges in an endless stream, and market is huge.Now predict, limit these electronic equipment development, aspect lcd technology, mainly contain 2 points: the one, the power consumption problem, for example 12 cun LCD portable computers now can provide power consumption very low center processor, memory is less than 1W, backlight～3W, driver～2W, the power consumption of backlight accounts for half of complete machine.Like this, read several hrs, will charge the battery, very inconvenience.Next is a brightness problem.Adopt reflected displaying device can remove backlight from.Kind of reflection type liquid crystal display technique scheme is being developed surplus in the of existing ten, [please refer to: A.G.Chen, et al., SID95DIGERST p 176 (1995); D-1L.Ting, et al., SID99DIGEST p 955 (1999) and I.Hiyama, O.Itou, Kondo, SID97DIGEST p 655 (1997)], wherein promising again polaroids that have more.This reflective liquid-crystal display will make illumination light (to showing that part of usefulness) loss more than 60%.The existing reflective STN that sells in market, AM-LCD reflectance peak cause display to carry out on background grey rather than as the blank sheet of paper generally 20%, and long-time the reading can make eye eyesight reduce.
Blank sheet of paper is a kind of extraordinary scattered light surface, and the reflectivity of standard white BaSO4 is decided to be one of percentage hundred, and high-grade copy paper can reach 90%, and newspaper can reach 70%.On such paper, even a little image of poor contrast or also can see clearly Chu at the weaker environment of lightness.This explanation is concerning people's vision, and reflected displaying device luminance factor contrast is more important.In addition, reflective demonstration must have high reflectance could realize that the better quality full color shows.The doing storage type (storage Mode) demonstration (abbreviation negativity cholesteric liquid crystal displays) with the nematic phase (nematic) of negative dielectric anisotropic (negative dielectric anisotropy) and cholesteric phase (cholesteric) composite material and [please refer to: G.H.Heilmeier of beginning of the seventies exploitation, J.E.Goldmacher, Proc.IEEE 57, P.34 (1969); E.B.Priestley, P.J.Wojtowicz, Ping Sheng " Introduction to Liquid crystals " Plenum Press, NewYork and London, P255 (1975)].Its structure is seen Fig. 1, and negativity liquid crystal material of cholesteric phase [3] is clipped between substrate [1] and the subtegulum [2], and transparency conducting layer [4] is coated on the inside surface of upper and lower substrate.This negativity cholesteric liquid crystal displays focal conic texture (focal conic texture) when bright attitude, has scattering power strongly to incident light.Display is very transparent when being in planar texture (Plane texture), and focal conic texture and planar texture all are stable states.Though this display has scattering power strongly,, its most scattered light is a forescatering.Reflective as if this display is made, need the forward-scattered light of focal conic texture is converted to scattered light backward, also need avoid the transmitted light of planar texture to be converted to scattered light backward simultaneously, just can obtain high reflectance and show.Utilizing the common planar catoptron is to address the above problem.
We utilize the optical total-reflection principle design a kind of have select the incident light reflection show off reflector plate (lazed retlector) [6], it can be with part forward-scattered light reflection the becoming back scattered light of focal conic texture.Simultaneously, it can also be limited in most of transmitted light of planar texture and show off in the reflector plate.The reflecting properties of this reflector plate [6] will match each other and with optical cement [5] they be fit together with the optical of display, just can obtain the reflective negativity cholesteric liquid crystal displays [8] of high reflectance.
Inventive principle:
One, some optical properties of negativity cholesteric liquid crystal
Negativity liquid crystal material of cholesteric phase [3] is to be mixed with 10: 1 to 10: 0.5 ratio by negativity nematic phase (dielectric anisotropy Δ ε～-5) and cholesteric phase, and is mixed with small amount of impurities (such as Australia is for cetyl).The physical parameter of potpourri: mean refractive index n～1.42; Optical anisotropy Δ n～0.2; Electricalresistivity～10
10Ω-cm and pitch ρ
0〉=10000A, if on the box (thickness d～6 μ m) [7] when not applying voltage, liquid crystal is in planar texture and sees its cloth loudspeaker lattice (Bragg) reflection wavelength of Fig. 2 (a) infrared in the box, and is very high to visible light transmissivity, faint scattered light only arranged, stable state.Dark attitude for reflective demonstration.When box being applied direct current (or low frequency) voltage, ion will be moved in the box, and liquid crystal will produce dynamic scattering (dynamic scattering), see size and d, Δ ε and the p of this voltage of Fig. 2 (b)
o -1/2Relevant.When voltage is excised, liquid crystal is transformed into focal conic texture, sees Fig. 2 (c), stable state.
To incident light forescatering in large quantities will take place, incident light scattering is backward in a small amount compared with the material of not mixing ion, and the focal conic texture scattering power is stronger, and evenly, this is the reason that this paper adopts the cholesteric liquid crystal potpourri of band ion.Selecting big Δ n, also is to have in mind from strengthening scattering power, and (＞500～1000Hz) voltages will produce metastable planar texture, see Fig. 2 (d), and light transmission is good when stable focal conic texture being applied high frequency.When voltage is excised, this metastable planar texture will return initial stable flat fabric.
In fact, in planar texture or focal conic texture, all there is a large amount of farmlands no matter be.Farmland in focal conic texture, the orientation of its screw axis is at random.Farmland in planar texture, the orientation of its screw axis is mostly perpendicular to glass substrate surface.Molecular force between the farmland is the orientation that can not change screw axis in the farmland, so no outer field action, structure is stable.In our experiment, this stablizing can reach decades.
Utilize low frequency (or direct current) and high-frequency drive when (claiming double frequency to drive again), when drive voltage amplitude was not enough, existing focal conic texture had planar texture again in the farmland in cholesteric liquid crystal.When the voltage of rapid excision this " underswing ", this existing focal conic texture has planar texture again, and same reason also can keep for a long time.We also can call multistable to this characteristic, can be used for gray scale and show.
(please refer to Zhao Jingan, Tong Shousheng, Ruan Liang, electronic letters, vol, No.2, p99 (1983),) utilize the negative dielectric anisotropic cholesteric liquid crystal to make display, also having an important advantage, its electro-optic response speed is faster than the prosperous display of positivity cholesteric phase liquid, adopt special driving method can obtain video speed, this paper introduces the planar texture of the negativity cholesteric liquid crystal box that we make and focal conic texture experiment and the result to the forescatering of incident light at this.Experimental provision is seen Fig. 3, is light source with helium-neon laser (λ=6328 ) [9], and the vertical sample box substrate surface of incident light is measured scattered light intensity (comprising transmitted light intensity) with photoelectric tube [11], and [9] and [11] all dispose light bright-coloured hurdle [10].θ is forward-scattered light and substrate normal angle.The measurement result that the angle of the forward-scattered light of planar texture and focal conic texture distributes is seen Fig. 4.(a) and (b) light intensity is to measure under the same conditions in.From (a) as can be known, the cone angle of the scattered light of planar texture～10 °.From (b) as can be known, the cone angle of the scattered light of focal conic texture～60 °.Largest light intensity is about in (b) 6 times in (a).
Two, has the design concept of showing off reflector plate [6] of selecting the incident light reflection
Our design show off reflector plate [6], its section structure is seen Fig. 5, is by refractive index n
p=1.52 polymkeric substance [12] or refractive index (n
p=1.52 glass) and high glass transition temperature (T
G2=140 ℃) polymkeric substance [14] form.Make isosceles three at the inside surface of polymkeric substance [14] and separate the shape groove, and at the surperficial aluminising [13] of these grooves.The glass temperature T of polymkeric substance [12]
G1＜T
G2
The base angle β size of isosceles triangle groove is one of important parameter of the design.It will determine some incident lights to be reflected out to show off reflector plate and some incident lights will total reflection take place and be limited in showing off (the selection incident light reflection function of promptly showing off reflector plate) in the reflector plate.As can be seen from Figure 4, as a kind of reflective demonstration, our design: will be limited in showing off in the reflector plate with the forward-scattered light of the planar texture of absolute value≤5 of substrate normal angle °; Reflect with the forward-scattered light of the focal conic texture of absolute value＞5 of substrate normal angle ° and to show off reflector plate.
When light from polymkeric substance [12] when cholesteric liquid crystal [3] is propagated, angle of total reflection i
cFor:
Be light from polymkeric substance [12] when cholesteric liquid crystal [3] is propagated, its incident angle 〉=68 °, total reflection will take place in this part light in polymeric layer, can not enter in the liquid crystal.In order to make and to reflect the incident light of penetrating sheet normal angle≤5 °, all total reflection can take place in polymkeric substance, the base angle β of isosceles triangle is:
β＝68°/2-5°＝29°
For with the incident light of substrate normal angle r＞5 ° (bigger r angle not being discussed) at this, be not all can both reflex in the liquid crystal.See that Fig. 6 incident light m and the n next from the right are parallel to each other, two bundle incident light differences are: incident light m shines leg-of-mutton left waist, its incident angle i
1Will be greater than i
c, can not enter liquid crystal; Incident light m shines leg-of-mutton right waist, its incident angle i
2Will be less than i
c, can enter liquid crystal.Equally, the incident light that comes from the left side, r＞5 ° shine right waist, all total reflections.What shine left waist can enter liquid crystal.This explanation: utilize this β=29 ° to show off reflecting piece,, can obtain: be limited in the forward-scattered light of the planar texture of absolute value≤5 of substrate normal angle ° and show off in the reflector plate from two-side lighting; Reflect with the forward-scattered light of the focal conic texture of absolute value＞5 of substrate normal angle ° and to show off reflector plate, enter liquid crystal again, strengthened focal conic texture forescatering light intensity, increased the reflectivity of display [7].
Polymer Dispersed Liquid Crystal (nematic phase or cholesteric phase) display, the optical property of its forescatering and scattering backward and negativity cholesteric display [7] have similarity.Utilize the reflector plate of showing off of the present invention also can strengthen the polymer dispersed liquid crystal display reflectivity.
Description of drawings:
Fig. 1 is reflective negativity cholesteric liquid crystal displays [a 8] structural representation
Fig. 2 be negative dielectric anisotropic cholesteric liquid crystal box [7] under direct current or HF voltage effect, the variation synoptic diagram of structure
Fig. 3 is the forward-scattered light distribution measuring experiment of negativity cholesteric liquid crystal box to vertical incidence light
Fig. 4 (a) is that the forescatering optic angle of planar structure distributes, and (b) is that the forescatering optic angle of focal conic texture distributes.The unit length of the ordinate (b) is 2 times in (a), and (b) unit length of the horizontal ordinate in is in (a) 1/2 times.
Fig. 5 be have select the incident optic angle show off the reflector plate schematic cross-section
Fig. 6 is the incident light m and the n that are parallel to each other that come from the right, ∠ r＞5 °.
Incident light m shines left waist, and all total reflections are to not contribution of scattered light backward.
Incident light n shines right waist, and scattered light is backward had contribution.
In the accompanying drawing with reference to label
Subtegulum 2 helium-neon lasers 9
Negativity liquid crystal material of cholesteric phase 3 smooth hurdles 10
Transparency conducting layer 4 photoelectric tubes 11
Show off reflector plate 6 aluminium mirror coatings 13
Box (negativity cholesteric liquid crystal displays) 7 glass temperatures are 140 ℃ polymkeric substance 14
Claims (6)
- Negativity cholesteric phase full color LCD [7] and a kind of have select the incident light reflection show off reflector plate [6], fit together with optical cement [5], form and show off the reflective negativity cholesteric liquid crystal displays of reflector plate [8].
- 2. require negativity cholesteric liquid crystal displays [7] according to right 1, its feature: the bragg reflection spectrum of liquid crystal material of cholesteric phase [3] is in invisible scope (for example infrared range of spectrum); The very optical index n of liquid crystal material of cholesteric phase [3] 11(n for example 11=1.45) less than the refractive index n of substrate [1], [2] g(n for example g=1.52); Liquid crystal material of cholesteric phase is big optical anisotropy Δ n (for example Δ n=0.2).
- 3. require to show off reflector plate [6] according to right 1 and form its feature by three kinds of different materials [12], [13] and [14]: polymkeric substance [14] has higher glass temperature T G2(for example: crystalline state polyolefin T G2=140 ℃); Polymkeric substance [14] upper surface is parallel isosceles triangle groove, and the incident angle (β=29 ° for example, absolute value≤5 ° that the incident angle of total reflection takes place) of total reflection takes place the decision of the size of its base angle β; The upper surface aluminising [13] of polymkeric substance [14] isosceles triangle groove; The refractive index n of polymkeric substance [12] pRefractive index n with substrate [1], [2] gIdentical (n for example p=1.52); The glass temperature T of polymkeric substance [12] G1Less than T G2
- 4. requiring optical cement [5] refractive index according to right 1 is 1.52.
- 5. require red, green, the blue three primary colours filter coating of bar shaped to do on last substrate inside surface according to right 1, bar shaped filter coating parallel (or vertical) is in the lip-deep groove of polymkeric substance [14].
- 6. require to show off reflector plate [6] is applicable to similar optical property to negativity cholesteric liquid crystal displays [7] display (for example polymer dispersed liquid crystal display) according to right 3, improve the display reflects rate.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013159505A1 (en) * | 2012-04-28 | 2013-10-31 | 京东方科技集团股份有限公司 | Liquid crystal panel and liquid crystal display |
| CN104062797A (en) * | 2014-07-14 | 2014-09-24 | 深圳市唯酷光电有限公司 | Liquid crystal handwriting device |
| CN106125420A (en) * | 2016-06-24 | 2016-11-16 | 京东方科技集团股份有限公司 | Display floater, display device and intelligent watch |
| CN115373169A (en) * | 2021-05-17 | 2022-11-22 | 肯特显示器公司 | Cholesteric liquid crystal device |
-
2003
- 2003-04-09 CN CNA031092918A patent/CN1536407A/en active Pending
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2013159505A1 (en) * | 2012-04-28 | 2013-10-31 | 京东方科技集团股份有限公司 | Liquid crystal panel and liquid crystal display |
| CN104062797A (en) * | 2014-07-14 | 2014-09-24 | 深圳市唯酷光电有限公司 | Liquid crystal handwriting device |
| CN104062797B (en) * | 2014-07-14 | 2017-06-16 | 深圳市唯酷光电有限公司 | Liquid crystal handwriting device |
| CN106125420A (en) * | 2016-06-24 | 2016-11-16 | 京东方科技集团股份有限公司 | Display floater, display device and intelligent watch |
| WO2017219770A1 (en) * | 2016-06-24 | 2017-12-28 | 京东方科技集团股份有限公司 | Display panel, display device, and smartwatch |
| CN115373169A (en) * | 2021-05-17 | 2022-11-22 | 肯特显示器公司 | Cholesteric liquid crystal device |
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