CN1162756A - Reflective liquid crystal display device - Google Patents

Reflective liquid crystal display device Download PDF

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Publication number
CN1162756A
CN1162756A CN96100549A CN96100549A CN1162756A CN 1162756 A CN1162756 A CN 1162756A CN 96100549 A CN96100549 A CN 96100549A CN 96100549 A CN96100549 A CN 96100549A CN 1162756 A CN1162756 A CN 1162756A
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China
Prior art keywords
liquid crystal
light
angle
reverberator
lcd device
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CN96100549A
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Chinese (zh)
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CN1140834C (en
Inventor
伊东理
近藤克己
桧山郁夫
藤井达久
菊地直树
平方纯一
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Panasonic Liquid Crystal Display Co Ltd
Japan Display Inc
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Hitachi Ltd
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Priority claimed from JP07078601A external-priority patent/JP3075134B2/en
Priority claimed from JP7286006A external-priority patent/JPH09127503A/en
Application filed by Hitachi Ltd filed Critical Hitachi Ltd
Publication of CN1162756A publication Critical patent/CN1162756A/en
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Publication of CN1140834C publication Critical patent/CN1140834C/en
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    • 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

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Liquid Crystal (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)

Abstract

A reflective liquid crystal display device comprises a liquid crystal cell formed by laminating upper and lower orientation layers, upper and lower electrodes, upper and lower substrates, and upper polarizer and lower polarizer and a liquid crystal layer. The liquid crystal cell is provided with viewing angle dependence so that the light transmission ratio of dark display section to bright display section for the light incident at the required angle may becomes less than 2 at the required azimuth angle of the liquid crystal cell, and the direction of the required azimuth angle is aligned to the direction of the main light source incident into the liquid crystal cell.

Description

Reflective LCD device
The present invention relates to a kind of reflective LCD device, relate in particular to the monochrome or the colour reflective formula display device of the large-screen high-resolution degree display that is suitable for using the XY electrode.
The present invention relates to a kind of reflective LCD device that can access color monochromatic demonstration of nothing and high brightness that it is characterized in that low-power consumption.
Along with the development more of this informationized society, portable data assistance is expected to spread to one of staff.The technical conditions of the portable data assistance of even now are not clearly stipulated as yet, but they will provide the communication function and the information processing function for principal computer.
Thereby be contained in that display device on each the sort of terminal all wishes to approach, light and low-power consumption, and because principal computer is the relation of multimedia machine, also requiring is colored the demonstration and animation display.
Satisfying the display device of " thin, light and low-power consumption ", is that non-reflective LCD device does not belong at present.But conventional reflective LCD device only is suitable for picture demonstration monochromatic and static state.
A kind of routine techniques that is used for this liquid crystal indicator is published in Japanese Unexamined Patent Publication No Sho No.51-69646, and its midplane and inclined-plane alternately are stacked on the undaform reverberator of a side; And at Japanese Unexamined Patent Publication No Sho NO.58-21 9526, wherein reverberator is capped aluminium foil or the aluminium film that is pressed with hexagon-shaped pattern, cone shaped pattern or trapezoidal pattern above one deck.
A kind of liquid crystal indicator of the prior art, reverberator are incorporated in the liquid crystal cell the inside.In addition, Japanese patent application publication No. Sho NO.62-1 06435 discloses a kind of liquid crystal indicator.Its reverberator a kind ofly is incorporated in the liquid crystal cell the inside by constitute the electrode of not only making reverberator but also making electrode such as aluminium by using.
Another routine techniques about liquid crystal indicator is published in Japanese Unexamined Patent Publication No Hei No.4-274217, wherein the diffraction grating pattern reverberator to the display surface of liquid crystal cell at an angle, and liquid crystal cell has an external reflector.This technology is used for improving the brightness that monochromatic reflection type liquid crystal shows.
But former routine techniques can not solve in the bright viewing area defect that the briliancy near dark viewing area part reduces, and that is to say, shade occurs, shows slinkingly and show and be replicated and problem that user's visibility is lost greatly.
On the other hand, newer routine techniques has a problem, even color filter and reverberator all are incorporated in the liquid crystal cell the inside, shows that for obtaining satisfied colour luminosity is still too low.
Reflective LCD device shows as light source that by using exterior light owing to do not need the relation of back light, so it is very thin, and power consumption is low, is suitable for battery operated.Display device also can be installed on the portable data assistance that is expected in the future to popularize rapidly.
A kind of improvement of display quality, specifically, the improvement of the display brightness when light shows and do not have color monochromatic a demonstration and all need to use reflective LCD device.
For example, with the reverberator of the display surface flash of light form at an angle of liquid crystal indicator and the liquid crystal indicator that has this reverberator all for as everybody knows.
The angled waveform reverberator that one of them plane and inclined-plane are alternately placed knows, and also has and a kind ofly also known through the reverberator that is molded into peak nest pattern, pyramid pattern or trapezoidal pattern with the aluminum foil type aluminium film surface.
Brightness improving when bright show and do not have color monochromatic show all and can not realize by the shape of regulation reverberator simply.
On the other hand, the optical path difference of phase plate and the structure of phase plate and polaroid know that refractive index is known three of phase plate axial distributions.
But the color monochrome of brightness improving during bright demonstration the and nothing shows all can not be by the optical characteristics of regulation phase plate and the layout structure of phase plate and polarizer are realized simply.
The display brightness of reflective LCD device improves and does not have color monochrome and is presented in the routine techniques and is not considered, so there is following problem.
As a reverberator that is used for reflective LCD device, there is the reflecting surface of a kind of reverberator (plane reflector) to be parallel to the plane of liquid crystal substrate, and the reflecting surface of a kind of reverberator (beam reflector) and the plane inclination of substrate are arranged.
Plane reflector is generally used for conventional reflective LCD device.A problem is that surface brightness is low in the reflective LCD device that uses plane reflector.
To narrate the reason of problem now, the user of this class display device sees liquid crystal indicator in the front.
As known to, liquid crystal indicator constitutes between two transparent substrates by liquid crystal layer being sandwiched and is sealed in up and down.
The electrode of matrix form and last oriented layer are located at the lower surface of substrate, and phase plate and last polarizer then are located on the end face of substrate.The bottom electrode of matrix form and following oriented layer are located on the top of subtegulum, and following polarizer then is located at the lower surface of subtegulum.Above-mentioned each subelement is formed liquid crystal indicator.
Plane reflector places the rear side of liquid crystal indicator, thereby forms reflective LCD device.
State the situation of plane reflector in the use, when customer location during at device positive, regular reflection to the user only from place the dead ahead to the light of light source.
But, because with being positioned at the dead ahead of liquid crystal indicator, being subjected to blocking of user from the light of light source, thereby not inciding in the liquid crystal indicator.
That is to say, only be the light of clothes, face or the like the primary event by the user by the light of frontal incident liquid crystal indicator, and the light intensity of each light is all very weak so that can not obtain enough incident lights.
Incide light in the device unlike from the light of light source or the like, being blocked by tilted direction by the user, thereby by plane reflector regular reflection and the oblique opposite side that is transmitted into.Because this light is not that reflection is to the user, even high light also is helpless to the brightness on surface.
As mentioned above, in the reflective LCD device that uses plane reflector, because the light path of user and incident light crosses one another, can not obtain the light of enough luminosity, the result only produces low surface brightness.
Using a beam reflector is well-known with the reflective LCD device that obtains brightness, and the problem of this situation is described with reference to Figure 28.In Figure 28, label 31 is represented beam reflector.
Beam reflector also is flash of light shape reverberator, and a plurality of fine reflectings surface that tilt to a specific direction keep flash state.Though the size of each reverse side all has been exaggerated in sketch, it only equals for example to say 35 μ m, and is decided to be such as 20 ° with the pitch angle (flash of light angle) on plane.
Thereby, in this situation, along the normal regular reflection of display surface to the user only incide light in the liquid crystal indicator from tilted direction with what solid line was represented, promptly by means of the inclination of each reflecting surface of beam reflector 31 and from the light of the light source L1 that is positioned at tilted direction.
Owing to the light that comes from the light source L1 that is positioned at tilted direction directly enters liquid crystal indicator and not blocked by the user.Event obtains luminous in a large number, so that under this situation, can thereby obtain the demonstration of higher surface brightness.
According to the reflective LCD device that uses beam reflector 31, though the improvement of sure acquisition brightness, a problem that occurs is to show the band look.
Now just be stated as the reason what buckle occurs.
In reflective LCD device, light is wanted transmission liquid crystal display twice, and (promptly when light enters element and light and is reflected) just arrives the user.
If the light of optional wavelength X is made as B (λ) by the brightness of LCD, its The Representation Equation below available then:
B(λ)＝E(λ)×Te(λ)×R(λ)×T R(λ)……(21)
Wherein E (λ) is the light intensity of incident light, T EThe transmission factor of liquid crystal indicator when (λ) being light incident, R (λ) is the reflection coefficient of reverberator, and T R(λ) be the transmissivity of light LCD when being reflected.
Coloured problem is exactly the correlativity to the wavelength of brightness B (λ).Because incident light is the light or the natural light that can be considered to colourless (white), incident intensity E (λ) and Wavelength-independent.And penetrate device and can constitute with a kind of like this mode, make reflection coefficient also not rely on wavelength.Thereby to the correlativity of the wavelength of brightness B (λ) just by T E(λ) and T RProduct decision (λ) is shown below:
B(λ)∝T E(λ)×T R(λ) …(22)
On the other hand because the transmitted spectrum of LCD depends on an angle, so when light enters the transmissivity T of LCD E(λ) and the transmissivity T of light LCD when being reflected RDuring (λ) respectively by light incident and the angle decision of the light path of light when being reflected.
Therefore, notice is placed on the angle of light incident LCD, and this LCD just is meant liquid crystal indicator.
In the situation of using plane reflector.Light path when light path during light incident and light are reflected is all in the normal direction of LCD.
Is T if establish LCD at the transmission spectrum of normal direction 1(λ) and use plane reflector, then obtain T E(λ)=T R(λ)=T 1(λ) as long as transmitted spectrum T 1(λ) do not have wavelength dependence, then brightness B (λ) just becomes colorless.
For this purpose, use the conventional LCD of plane reflector to design to such an extent that make transmitted spectrum T 1(λ) become colourless.
Otherwise, during beam reflector 31 in using Figure 28, though the light path when light is reflected in the normal direction of filter crystal display, the light path during light incident is not at the LCD plane normal and in sideling direction, shown in sketch.
As mentioned above, because the transmitted spectrum of LCD depends on angle, even at the transmitted spectrum T of plane normal direction 1(λ) there is not the correlativity of wavelength.But always not colourless coloured often in other words of the transmitted spectrum of tilted direction.
Thereby under this situation, demonstration is to be with look.
As mentioned above, when showing the band look, the visibility of liquid crystal indicator has just deteriorated significantly, and consequently colourless property image brightness equally is a key property of LCD, in case the colourless property that shows is worsened under high brightness, just can not obtain high-performance.
Therefore, in the reflective LCD device of routine,, just there is such problem owing to do not realize the raising of brightness and colourless property, so that the reflective LCD device that can not obtain to have high brightness and good visibility.
Thereby one object of the present invention addresses the above problem exactly.And provide a kind of have high briliancy and in monochromatic or colored the demonstration, do not have show slinkingly the reflective LCD device that shows shade.
Above-mentioned purpose of the present invention can reach by a kind of reflective LCD device, this reflective LCD device comprises: reverberator and one by superimposed oriented layer up and down, upper/lower electrode, go up subtegulum and above liquid crystal layer and below fitly arrange the liquid crystal display that the polarizer up and down that makes it to face is respectively mutually formed.
Liquid crystal cell has such visual angle correlativity, for example for the light with desired angle incident at desired position angle, and desired azimuthal direction is with inciding main light source direction of light in the liquid crystal cell on time, can obtain dark viewing area to the transmissivity of bright viewing area less than 2.
Purpose of the present invention also can reach by desired azimuthal direction is become 90 ° or the horizontal direction of aiming at reflective LCD device with user's position angle.
On the other hand, reflective LCD device be one by superimposed polarizer in order.Go up substrate for one, a top electrode is gone up oriented layer, a liquid crystal layer, a following oriented layer, a bottom electrode and the liquid crystal cell that subtegulum forms for one.
Purpose of the present invention can make that the main light source light that incides liquid crystal cell can be in the direction reflection at ± 10 ° of visual angles by form a reverberator between bottom electrode and subtegulum, and between last substrate and this reverberator, form a color filter or by form between bottom electrode and the subtegulum reverberator make the main light source light that incides liquid crystal cell can be at the visual angle 20 ° the direction reflection and between last substrate and reverberator color filter of formation reach.
In addition, when a voltage was added on the liquid crystal layer, the molecule axis of liquid crystal layer was registered to perpendicular to main light source and incides direction in the liquid crystal cell.
According to above-mentioned each structure, has the liquid crystal cell that for example obtains being close to 1 such visual angle correlativity for contrast with the light of desired angle incident at desired position angle, when liquid crystal indicator used, its desired azimuth direction was aimed at the incident direction of key light.
So, eliminated by ripple by bright viewing area and by the light of bright viewing area reflection with by dark viewing area and by the difference between the light of bright viewing area reflection, thereby provide one to have good visibility and shadeless reflective LCD device.
Generally, from above main light source light below when using, the user is sitting in the opposite of liquid crystal indicator.In other words, the user the liquid crystal indicator horizontal positioned and from above use it below the light of light source, like this, if desired position angle and display surface upward to aiming at, just can avoid occurring shade.
If liquid crystal indicator is used under the special environment, then desired azimuth direction will be aimed at the horizontal direction of liquid crystal indicator.
Other direction if reverberator is formed between bottom electrode and the subtegulum, that is to say, on subtegulum (reversed arrangement), then light does not pass through subtegulum.As a result, incident light has just solved with the problem of reflected light by different color filters, and the optical axis that incident optical energy is continued to use the family directly reflects.
In other words, reverberator satisfies the directly requirement of reflection, makes that the brightness that is absorbed by color filter is compensated, thereby can obtain having the reflective LCD device of bright property and good visual degree.
An object of the present invention is to provide a kind of reflective LCD device of having realized improving display brightness and colourless property.
According to the present invention, its purpose realizes by a liquid crystal indicator with a phase plate and a beam reflector, is n if be located at the index of the phase plate of mutually perpendicular photoelectricity major axes orientation in the phase plate plane wherein xAnd n y(n x＞n y), and to establish phase plate be n in the refractive index of thickness direction z, the expression below then satisfying.
0.3≥(n z-n x)/(n y-n x)
According to the present invention, its purpose realizes by a liquid crystal indicator, wherein when the optical path difference of phase plate during in 320nm to 420nm scope, then the direction that the direction of the orientation of two oriented layers (being positioned on the apparent surface of the transparent substrate up and down of clamping liquid crystal layer) is divided equally is decided to be 0 ° in orientation, and by on the portion of transparent substrate when watching, define the position angle counterclockwise, the position angle of following polarizer absorption axes places in 140 ° to the 180 ° scopes, the position angle of the slow axis of phase plate places in 45 ° to 80 ° the scope, and the position angle of going up the polarizer absorption axes is in-10 ° to 35 ° scope.
Moreover, according to the present invention, its purpose realizes by LCD, when wherein the optical path difference of phase plate is in 540nm to 680nm scope, the position angle of following polarizer absorption axes is in 140 ° to 185 ° scopes, the position angle of the slow axis of phase plate is in 45 ° to 80 ° scopes, and the position angle of last polarizer absorption axes is in 9 ° to 35 ° scopes.
Hereinafter will be stated as the reason what this purpose realizes by apparatus of the present invention.
In the present invention, along the plane normal direction with along two transmitted spectrums of LCD tilted direction, be made to colourless simultaneously by said apparatus.
At first, narration is used for form the device of transmitted spectrum in the normal direction on LCD plane.
The colourless property of high-transmission rate, transmitted spectrum and a high-contrast (being approximately 10: 1 under the situation of reflection) all are the requirements to LCD.In order to satisfy desired complete characteristic, the optical condition of polarizer and phase plate is the status of a sovereign angle of polarizer transmission axle, the position angle of the slow axis of phase plate.The phase differential of phase plate has all obtained optimization in the present invention.
Be the optical condition that makes the plane normal direction and phase differential the best of phase plate, notice is placed on the refractive index n by two kinds of photoelectricity major axes orientations in the phase plate plane xAnd n y(n x＞n y) between the phase differential of difference definition on.Though the number of phase plate can be made as an optional number, the expense of considering here increases only with a phase plate.
Now narration is used for producing the device of two colourless transmitted spectrums at the tilted direction of the normal direction on plane and LCD.
The visual angle of optical characteristics depends on the refractive index ratio of three axles of phase plate.
Thereby in the present invention, the refractive index ratio of three axles of phase plate is defined as following expression
0.3≥(n z-n x)/(n y-n x)
When the optical condition that keeps phase plate and polarizer makes that the transmitted spectrum of plane normal direction is colourless, the refractive index n of phase plate thickness direction zBe optimized.
Thereby, even using beam reflector and light path to become the occasion of the normal direction on oblique LCD plane, transmitted spectrum during light incident and all be colourless at the transmission spectrum of plane normal direction, thus when light was reflected, transmitted spectrum became colourless thereupon.As obviously being seen by expression (22), the colourless demonstration of reflective LCD device is obtained.Owing to used beam reflector in this situation, obtained higher brightness, the colourless property both of higher brightness and demonstration has as a result reached.
Fig. 1 illustrates the sectional view of liquid crystal indicator according to an embodiment of the invention;
Fig. 2 illustrates the sectional view of liquid crystal indicator in accordance with another embodiment of the present invention;
Fig. 3 illustrates the sectional view of the liquid crystal indicator of another embodiment according to the present invention;
Front elevation according to the portable data assistance of liquid crystal indicator of the present invention above illustrating, Fig. 4 is installed.
Fig. 5 illustrates the definition that angle of light, user's optical axis angle and LCD tilt;
Oblique view according to the laptop PC of liquid crystal indicator of the present invention above illustrating, Fig. 6 is installed;
Fig. 7 illustrate in use the display pitch angle and the measurement result of user perspective;
Fig. 8 illustrates the shape of the cutter that is used for making in one embodiment reverberator of the present invention;
Fig. 9 illustrate the position angle that is applicable to liquid crystal cell of the present invention and contrast to another embodiment of relation;
Figure 10 (a) illustrates the sectional view of the capable reverberator in display surface of its air spots to 10 (i);
Figure 11 illustrates the shape of tool that is used for making in another embodiment reverberator of the present invention;
Figure 12 illustrates a liquid crystal indicator and how to be used in the office;
Figure 13 illustrates the sectional view of reflection characteristic of the reverberator of brief description surface local bending;
Figure 14 illustrates the amplification sectional view of reverberator shown in Figure 10 (g);
Figure 15 (a) illustrates an embodiment who how to make reverberator of the present invention to 15 (d);
Figure 16 (a) illustrates another embodiment that how to make reverberator of the present invention to 16 (e);
Figure 17 illustrates an example of the transmitted spectrum of the redness of high-transmission rate, green hook and Lan Se color filter;
Figure 18 is illustrated in the bright display view angle characteristic of embodiment 15 and 16 liquid crystal indicators of introducing;
Figure 19 illustrates the sectional view of the reflective LCD device that is used to illustrate shade;
Figure 20 (a) and 20 (b) illustrate the position angle of the liquid crystal cell that is used for liquid crystal indicator and the definition of user side's parallactic angle;
Figure 21 illustrates an optical indicatrix;
Figure 22 illustrates three directions of the cross section part of expression optical indicatrix according to the impressed voltage variation;
Figure 23 illustrates the variation of the optical indicatrix cross section part that is caused by impressed voltage;
Figure 24 illustrates polarization (△) variation of liquid crystal cell of the present invention and the relation between the contrast;
Figure 25 illustrates the position angle that is suitable for liquid crystal cell of the present invention and an embodiment of the relation between the contrast;
Figure 26 illustrates the sectional view of conventional reflective LCD device;
Figure 27 illustrates the sectional view of a conventional colour reflective formula liquid crystal indicator;
Figure 28 is a cross sectional view, and an example of the reflective LCD device of the beam reflector of using an embodiment is shown;
Figure 29 is the explanation sketch of an amplification, and an example according to the reflecting surface of beam reflector of the present invention is shown;
Figure 30 is projected in (S 1, S 2) an explanation sketch of Pu'an card thunder ball on the plane, the light bevel that is used to represent to have a wavelength passes the polarization state of liquid crystal layer;
Figure 31 is projected in (S 1, S 2) an explanation sketch of Pu'an card thunder ball on the plane, be used to represent to set the position angle of slow axis of phase plate and the method for optical path difference;
Figure 32 is a performance plot, and the dependence of the colourless degree W of transmission in the LCD to the phase plate optical path difference is shown;
Figure 33 is an explanation sketch, and the relation between the colourless degree W of liquid crystal indicator transmitted light and the △ nd of liquid crystal layer (birefraction of liquid crystal layer and the product of bed thickness) is shown;
Figure 34 is an explanation sketch, and the elevation angle and azimuthal definition among the present invention are shown;
Figure 35 is a performance plot, and the parameter n of the colourless degree W of transmitted light in the liquid crystal indicator to the refractive index size of three axles of expression phase plate is shown 3Dependence;
Figure 36 is an explanation sketch, and an example of the oval ball of index of phase plate is shown;
Figure 37 is an explanation sketch, and another example of the oval ball of index of phase plate is shown;
Figure 38 is a performance plot, and the characterisitic parameter n of the colourless degree W of transmitted light in the liquid crystal indicator to the refractive index size of three axles of expression phase plate is shown 3Dependence;
Figure 39 is a performance plot, and the dependence of the colourless degree W of transmitted light in the liquid crystal indicator to the optical path difference of phase plate is shown;
Figure 40 is an explanation sketch, and the relation between the colourless degree W of transmitted light in the liquid crystal indicator and the △ nd of liquid crystal layer (double refractive inde of liquid crystal layer and the product of bed thickness) is shown.
Before the details of explanation various embodiments of the present invention, explaining in detail below becomes instead Penetrate the reason of shade of a specific question of formula liquid crystal indicator, reflective coler display The problem of device, and the method that addresses these problems.
Shadow problem at first is described. Figure 19 shows to illustrate the reflective of shadow problem The sectional view of liquid crystal indicator. Liquid crystal cell comprises upper 12, one liquid crystal layers 10 of substrate And subtegulum 22.
As shown in figure 19, reflector 31 places the below of subtegulum 22, and subtegulum 22 Place between reflector 31 and the liquid crystal layer 10 to separate reflector 31 and liquid crystal layer 10. Reflection The reflecting surface of device 31 is parallel to the shiny surface (display surface) of substrate 12. This is of the present invention A feature.
Figure 19 has omitted other elements beyond the said elements. Light incide in the liquid crystal cell and Reflection on the reflector 31, and then pass liquid crystal cell and arrive this user's eyes 72. The user The light courage of admitting and intensity are determined by the product of following three parameters.
T θ: liquid crystal cell is to the transmissivity of incident light
T 1: liquid crystal cell is to the transmissivity of transmission
R: the reflectance factor of reflector.
Rope-lay conductor zone among Figure 19 is a dark viewing area. Here, at first illustrate and leaving Watching of the bright viewing area of the boundary vicinity of together dark viewing area. Light incides and is positioned at bright viewing area Point 94.
Then, this light passes bright viewing area by point in pip 95 reflections of reflector 31 96 walk out and arrive the eyes 72 that are positioned at the user on user's boresight direction.
On the other hand, when watching the bright viewing area on border, contiguous dark viewing area, then incident light arrives Reach the point 91 that is positioned at dark viewing area. After pip 92 reflections, this light is from being positioned at bright demonstration The point 93 in district is walked out.
So, the user sees that the light and entering that enters bright viewing area and there reflection shows slinkingly Show district and the light that reflects there. Two light enter liquid crystal cell with same angle. Thereby, the moon The appearance of shadow is to be made by the difference of light transmission between the bright viewing area of liquid crystal cell and the dark viewing area Become.
In other words, if the light transmission of bright viewing area greater than the light transmission of dark viewing area, Then enter dark viewing area and by the brightness of the light of there reflection will be lower than enter bright viewing area and by The there reflection.
As a result, show slinkingly and show that seeming similarly is its shade of reflection. Here it is is assorted In case dark viewing area is (lower to the ratio of the optical transmission coefficient of bright viewing area along the incident direction of light Literary composition is called contrast) equal can not occur the reason of shadow at 1 o'clock. Contrast from 1 more away from, the moon Shadow occurs more clearly.
Moreover shade is subjected to the impact of the structure of reflector to a great extent. Anti-with the plane Penetrate the situation of the reflective LCD device of device (its reflector is parallel to display surface), the user What see is with the reflective display face that is comprising scattered light.
In other words, at the reflection spectrum of this situation by the light from variant direction reflection Form the difference of the light transmission between each incident light thereby eliminated from the outside that (brightness is equal Spare), and contrast becomes close to 1. Here it is, and why shade becomes unconspicuous Reason. In this situation, the brightness of whole display surface is uniform.
Otherwise, have one mainly with reflective to the reflector of user's optical axis of light reflection The situation of liquid crystal indicator, that is in the satisfied situation that requires that directly reflects of a reflector, What the user saw is direct catoptrical display surface, so this light becomes brighter than scattered light.
But the reverberation of this situation is the light of single incident direction reflection. So, this light Be subjected to a great extent the impact of the contrast of incident direction, it is clear to cause shade to occur.
The present invention has been noted that shade can adjust to 1 by the contrast of light incident direction Eliminate, shade can alleviate by making contrast more close 1 in other words.
Below, will the situation of 8 tonal gradations that show black-and-white image be discussed. Suppose now The light transmission that bright grade shows is T1, i.e. bright demonstration. Suppose by the order of brightness later on Be T2，T 3，T 4，T 5，T 6，T 7And T8(show slinkingly and show). For example, under indoor light, T1To T8Brightness be 30 nits, 27 nits, 23 nits, 19 nits, 14 nits, 10 nits, 7 Nit, and 4 nits.
If the brightness ratio T of shade2Bright, then this shade does not cause instead in tonal gradation shows To tonal gradation. In this situation, the contrast of incident direction must be 1.1 or 1.1 Below (30 spies/27 nits). But in fact, the brightness during tonal gradation shows is often aobvious Show a brightness continually varying picture. T8(show slinkingly and show) is difficult to contiguous T2。
Thereby, if the contrast of light incident direction is below 2 or 2, then at T8With the T that places 8 grades of gray scale centers5Between not have image reverse. (T5/T 6)＝1.4，(T 6/T 7)＝ 1.4，(T 7/T 8)=1.75 that is to say, making contrast is 2 or the lower shade that alleviates Necessary condition.
On the other hand, a liquid crystal indicator is to be added to liquid crystal layer at external voltage to change liquid crystal Realize bright demonstration in the situation of layer orientation and show slinkingly showing. Contrast is with the increase of change in orientation Increase. Thereby contrast becomes close to 1 in the littler direction of change in orientation.
In this situation, problem is not the variation of apparent orientation, but the light that change in orientation causes Learn the variation of characteristic. " apparent variation " is one of change of optical properties.
Suppose that now liquid crystal layer is cut into thin slice and is parallel to up and down two substrates. Power on by adding Press, the maximum of orientation changes and appears at each central core of cutting layer namely apart from upper subtegulum farthest In that one deck.
Because the minimum orientation that is subjected to up and down on-chip oriented layer generation of central core limits Impact. Thereby the variation of considering the central core orientation just means the liquid crystal layer that consideration is all.
Figure 20 (a) and Figure 20 (b) illustrate the orientation to the liquid crystal cell of liquid crystal indicator (41) The definition at angle () and user's azimuth ( 1). Figure 20 (a) illustrates the side in the single liquid crystal cell The definition of parallactic angle ().
As shown in the figure, with the orientation (LD2) on upper on-chip orientation (LD1) and the subtegulum Between the direction of angle bisecting be defined as 0 ° of azimuth. Just 0 ° in 0 ° of azimuthal direction Azimuthal axis. Then, by counterclockwise determining the azimuth.
In addition, light incident (IL) is used intersecting lens (CL) and 0 ° of azimuth to the direction in the liquid crystal cell The angle that axis consists of is determined, is comprised that at intersecting lens light incides axis and the demonstration of liquid crystal cell The plane of incidence of face normal (PD) and display surface intersect.
60 ° of so, being defined by in liquid crystal cell with the light of 60 ° of azimuth incidents are azimuthal The angle of direction incident. The incidence angle of certainly, at this moment awaiting the honour of your presence is exactly by incident light axis and display surface method The angle that line consists of. Hereinafter, the azimuth of abbreviation just refers to the liquid crystal cell shown in Figure 20 (a) The azimuth.
At central core, have only the ascending angle (angle that the axis of substrate surface and liquid crystal molecule constitutes) of liquid crystal molecule axis to change with impressed voltage.When not having making alive, ascending angle almost is 0 °.Angle increases when adding voltage.The direction of liquid crystal molecule axis is all fixed no matter add not making alive.
Figure 20 (b) illustrates the definition to user side's parallactic angle of liquid crystal indicator.Generally, when liquid crystal indicator uses, that is to say that when the guidance panel of liquid crystal indicator was used, it was a horizontal positioned.
As shown in the figure, the horizontal display surface 113 of liquid crystal indicator thereby both be defined as the horizontal direction of using display is defined as the direction of user side's parallactic angle of 0 ° again.This direction is assumed to the benchmark that uses LCD.Determine direction then counterclockwise.
In addition, the direction that light incides the liquid crystal indicator in the use determined by the angle that user side's parallactic angle axis of an intersection axis and 0 ° constitutes, and includes that light incides the axis of display surface of liquid crystal cell and the light entrance face of display surface normal then intersects with display surface on this intersection axis.
For example, be defined by when using liquid crystal indicator horizontal direction is become the light of user side's parallactic angle incident of 60 ° with the light of user side's parallactic angle incidents of 60 °, incident optic angle at this time is an angle that is made of incident light axis and display surface normal.
Generally, with the user location angular direction reflection of the light of user side's parallactic angle incident of 60 ° at as shown in the figure 240 ° (=60 °+180 °).But under this situation, light also can be with 270 ° user location corner reflection, and in use this direction is perpendicular to liquid crystal indicator.Reflection of light then is made of reflection optical axis and display surface normal.
Use under general state in the liquid crystal indicator, key light is come the display surface of liquid crystal cell from user side's parallactic angle of 90 ° that is perpendicular to the direction of the liquid crystal indicator using.This light is also in the direction reflection perpendicular to user side's parallactic angle of 270 ° of liquid crystal indicator, if light does not then define the user location angle in the direction reflection of display surface normal.
Because central core is enough thin, thereby can think a birefringent medium.Figure 21 illustrates an optical indicatrix.The viewing angle characteristic of birefringent medium optical characteristics can be described below with optical indicatrix shown in Figure 21.
Optical indicatrix (IE) is one and is defined in the ellipsoid that the real space is three refractions.Axis direction is parallel to the optical main axis line of birefringent medium.Each axial ellipsoid length is exactly the refraction coefficient of this direction.Supposition light is by (x now 0, y 0, z 0) direction incide in the birefringent medium.
The birefringence of light-receiving can far be found out by optical indicatrix is carried out following geometry thus.Imagine one and include the center of optical indicatrix and perpendicular to (x 0, y 0, z 0) xsect.This is transversal just to become an ellipse, but the difference between long axis of ellipse and the minor axis to be taken as be by (x 0, y 0, z 0) birefringence that light received of direction incident.
For a liquid crystal layer (being central core), optical indicatrix looks like a rugby shape.The major axis of optical indicatrix is parallel to the mean direction of liquid crystal molecule axis.At central core, only there is the ascending angle of the major axis of indicatrix to change.
Below, with the dependence of examination one downwards angle of visibility to the cross sectional shape variation of optical indicatrix, Figure 22 illustrates the cross sectional shape attitudeization of refraction ellipsoid is learned in expression when a voltage is added on this liquid crystal layer three directions.
Note a shown in the figure, three directions of b and c (a: the mean direction of liquid crystal molecule axis in the central core, the opposite direction of b: a; The vertical direction of and c: a).
Figure 23 illustrates the variation of the optical indicatrix sectional view that is caused by impressed voltage.
As Figure 23 (a) with (b), under the alive outside situation, the changes of section of a and b is very big.When not having impressed voltage, the cross section of a and b all is oval.In the situation of a, when adding voltage, major axis shrinks and almost the cross section is become a circle.In the situation of b, the major axis elongation increases its ellipse property.Conversely, shown in Figure 23 (c), the cross section of c then be change very little.
So, less when estimating to add voltage in the optical characteristics of the direction liquid crystal layer that rises perpendicular to central core liquid crystal molecule axle, and contrast approaches 1.Thereby if this direction alignment light incident direction, shade just can alleviate.
In addition, show slinkingly and show with bright demonstration and also can regard when adding voltage variation as, contrast is become regard that near 1 polarization variations diminishes as by the polarisation of light of liquid crystal layer.Top view is by the method validation of measurement polarization as described below.
For bright demonstration with show slinkingly and show that light is assumed to E by the polarization of liquid crystal layer BAnd E D, and use standard fuel parameter (Stokes the pa-rameters) (S that determines by following expression (1) to (3) 1, S 2, S 3) E BAnd E DBe expressed as (S 1B, S 2B, S 3B) and (S 1D, S 2D, S 3D).
S 1=(E X 2-E Y 2)/(E X 2+ E Y 2) ... (expression 1)
S 2=(2E XE YCos δ)/(E X 2+ E Y 2) ... (expression 2)
S 3=(2E XE YSin δ)/(E X 2+ E Y 2) ... (expression 3)
In the superincumbent formula, E X, E Y, δ is illustrated in the electric-field vector of giving X-direction, at the electric-field vector of Y direction, and E XAnd E YBetween phase differential.The polarization variations that is caused by impressed voltage is defined as △ and with following use (S 1B, S 2B, S 3B) formula quantize.(S 1D, S 2D, S 3D) be a constant.
△=C X(1-S 1BS 1D-S 2BS 2D-S 3BS 3D(expression 4)
The maximal value of △ equals 1, and at this time, the polarization that is caused by impressed voltage becomes maximum, and minimum value is 0, adds that at this time voltage can not differentiate polarization variations.
Figure 24 illustrates the degree of polarizationization (△) that appears among the present invention in the liquid crystal cell and the relation between the contrast.Transverse axis among the figure is the position angle in the defined liquid crystal cell of Figure 20 (a).
Z-axis is exactly the variable quantity (△) of polarization, △ shows when the position angle is 0 ° or 180 °, the variable quantity of polarization almost becomes 0, the position angle of 0 ° or 180 ° equals direction (c) shown in Figure 22, under these conditions, the dependence of the contrast of position angle and incident angle and liquid crystal cell is all measured.
Figure 25 illustrates an embodiment of the relation between the contrast that is used for position angle and liquid crystal cell of the present invention.The visual angle dependence of liquid crystal also is shown.As shown in the figure, when the position angle was 0 ° or 180 ° (c) direction that promptly equals among Figure 22, contrast became especially little and becomes and approaches 1 most, and this experimental results show that with regard to using top view is correct.
According to top result, if proved liquid crystal indicator make make the visual angle dependence that has-at specific position angle with the light of specific angle incident, contrast (light transmission of dark viewing area to bright viewing area) becomes 2 or following-liquid crystal cell generate and liquid crystal cell is arranged direction of light from light source is aimed at a specific position angle of liquid crystal cell, shade just can alleviate.
Below, will be described as follows reflections of high brightness formula color liquid crystal display arrangement:
Figure 26 illustrates the sectional view of conventional monochromatic reflective LCD device, and why LCD can not be that the reason of color-type display has two: (i) reflectivity is not to mix the luminosity drop that causes with (ii) multichannel.
Illustration (i) at first.Light by the reverberator reflection is divided into strong direct reflected light (RL) of high light and the strong scattered light (SL) of the low light level.
In the middle of the light of directly reflection, incident angle and reflection angle equate for the reflecting surface of macroscopic view, and in the middle of scattered light, does not but wait at these two angles.The surface of reverberator has fine uneven, so it has many fine reflectings surface with different line of vision hooks.These distributions of fine reduce along with the decline of line of vision hook quantity.
Fine reflecting surface promptly is being parallel at the reflecting surface of evenly tilt (0 °) on the reflecting surface of macroscopical reflecting surface and is distributing at most, and most light all reflects on such reflecting surface.
Generally, to illustrate that as the back user watches liquid crystal indicator at 0 ° visual angle.Here it is, and the user sees when why using plane reflector is the strong scattering of the low light level, as shown in figure 26, in other words, if the reflectivity deficiency does not then have the directly light of reflection.
In this situation, the direct reflection that make light directly be reflected in the direction of user's optical axis requires to be not being met.This is because the cause that LCD is influenced by shade to a great extent.
Below, with illustration (ii).Figure 27 illustrates conventional colour liquid crystal display device sectional view.Utilize this figure, the explanation device is had the structure of reflective LCD device of color filter and the jump in brightness that is caused by liquid crystal indicator itself just.Color filter 51 is formed in the middle of the substrate of liquid crystal layer 10 and one of last subtegulum 12 and 22.
In the embodiment shown in Figure 27, it is formed near last substrate 12 places, is adorning the situation of the reflective liquid-crystal display of reverberator below subtegulum 22, and subtegulum is formed between color filter 51 and the reverberator 31 they are separated.At this moment, filter thickness is 100 μ m, and the about 1mm of the thickness of subtegulum, thereby incident light is different with light path between the reflected light.
In other words, one " incident light and the problem of reflected light by different filters " appears.If light is by different color filters, then transmission spectrum is also different, thereby light is absorbed fully by different color filter (for example, red and blue look color filter).The so many reasons of brightness landing were that light must pass through thick subtegulum when why light was by different color filter.
Situation at (i).The direction that the reverberator that reflectivity can provide by use is directly guided to user's optical axis with reflected light solves direct reflection problems and improves.
In situation (ii).The top that reverberator is contained in subtegulum is sentenced in abutting connection with liquid crystal layer and is avoided light to pass through subtegulum.So just solve the above-mentioned problem that causes by different color filters by light.
In the situation of monochrome display, any method all can be used for improving brightness independently.But in the situation of color monitor, any method can both accept enough to be used for the colored brightness that shows.Because color filter is colored by absorbing light performance, this make light pass through color filter once after, brightness drop to 1/3 or below.
For by solve simultaneously (i) and (ii) two problems realize colored demonstration, structure of the present invention must adopt.Say again,, also must adopt structure of the present invention to solve shadow problem even directly the requirement of reflection is satisfied.
Hereinafter, some embodiments of the present invention are described with reference to the accompanying drawings.
Embodiment 1
Fig. 1 illustrates the sectional view of liquid crystal indicator in the one embodiment of the invention.
The structure of the liquid crystal indicator among Fig. 1 is as follows: from display surface, superimposed in order one an of display element is gone up 13, one phase plates 19 of polarizer, go up substrate 12 for one, 14, one of a top electrode is gone up 11, one liquid crystal layers 10 of oriented layer, next oriented layer 21 down, 22, one following polarizers 23 of 24, one subtegulums of a bottom electrode, and a reverberator 31, each electrode is connected to a driver circuit.Reverberator 31 below subtegulum 22, the opposite side of display surface.
Each substrate is all made with glass.It is that 1000A, width are 310 μ m that each electrode includes thickness, and the ITO that arranges with 20 μ m at interval.Each oriented layer all uses the graininess polyimide polymer to make and handle to form oriented layer with a polishing, and the condition of processing is: otch 0.4mm, rotating speed 1000rpm, speed of feed 33m/s.
Top rake is 4 °, and reversing is 240 °.Liquid crystal layer comprises nematic crystal and chirality additives.Bed thickness 5.7 μ m and liquid crystal material are MJ63928 (Melk company).△ n be 0.145 and △ nd be 0.83mm.The chirality additives are that 58n (Melk company) and content ratio are 0.9% (percent by weight).
The axis angle that light incides down polarizer is decided to be 90 ° and incide the fixed position angle to 20 ° of the angle of axis of polarizer.Phase plate is formed between polarizer and the last substrate, show the angle of axis fixed to 50 ° the position angle and when the 550nm wavelength nd be decided to be 0.63 μ m.
So the direction of decision directional process is made subtegulum.The contrast of LCD to the visual angle dependence as shown in figure 25, this figure shows that near 0 ° of position angle of liquid crystal cell contrast becomes no better than 1.To the light with 0 ° of such position angle incident, contrast becomes no better than that 1 liquid crystal cell is used to make liquid crystal indicator, makes the direction at the position angle (degree) of liquid crystal cell be registered to the direction of 90 ° of user side's parallactic angles of the display surface of the brilliant unit in Huaihe River.
Fig. 4 illustrates the front elevation of the portable data assistance that uses liquid crystal indicator of the present invention.This illustrates the outward appearance that is installed in the liquid crystal indicator on the portable data assistance.Liquid crystal indicator comprises 111, one guidance panels 112 of an antenna, and a display panel 113.
Fig. 5 illustrates angle of light (θ 1) user perspective (θ 2) and the pitch angle (θ of LCD 3) definition, this definition will be illustrated by an embodiment who is used for the LCD of laptop PC.
Incident angle is made of the axis of the light of injecting from light source and the surface normal of liquid crystal display.In the drawings, turn clockwise and be decided to be (+) of forward.
The visual angle is that the direction and the display surface normal of eyes of user constitutes by the optical axis.Be rotated counterclockwise in the drawings and be decided to be forward (+).
The pitch angle represents that the display surface of LCD is to putting the degree of tilt of putting the desktop normal that uses liquid crystal indicator.Turn clockwise and be decided to be forward (+).
The user is at the outdoor application portable data assistance, and the most frequent is about 20 ° pitch angle and about 20 ° visual angle.Generally, incident light direction at this time is user side's parallactic angle of one 90 °.The reason of liquid crystal indicator of the present invention why that Here it is by the 0 ° of azimuthal direction of liquid crystal cell and the direction of 90 ° of user side's parallactic angles are alignd and made.In this situation, be about 20 ° as the incident angle of the sunlight of main light source.
In order to make main incident light directly promptly satisfy the directly requirement of reflection in the boresight direction reflection from the light source of open air, almost must be in about 20 ° view directions reflection with the light of 20 ° of incidents.
Because visual angle and incident angle both are 20 °, thereby the plane reflector that reflecting surface is parallel to display surface is used to the light of directly reflection is guided to boresight direction.
The display characteristic of this portable information terminal ties up to outdoor measurement.The brightness of the bright viewing area of the dark viewing area of adjacency is 56cd/m 2, then be 80cd/m away from the brightness of the bright viewing area of dark viewing area 2The contrast of Qu Zhiqu is 1.4.This contrast is represented the degree of dark viewing area.
In other words, this means if this ratio is 1 that then first shade occurs, and this ratio is big more, shade is remarkable more.This has proved that also shade is not obvious and visibility is fine.
Just as explained above, because directly the incident direction of light of reflection is registered to the direction of user perspective, thus can be subjected to effective utilization from the light of light source (sun), thus bright demonstration obtained.
Moreover to be registered to user side's parallactic angle of 90 ° be the incident direction of light to azimuthal direction of 1 liquid crystal cell because its contrast becomes at 0 ° of position angle no better than, thereby just obtained the reflective LCD device that shade is not obvious and visibility is good.
Embodiment 2
In present embodiment 2, the liquid crystal indicator among the embodiment 1 is installed on the laptop PC and under the condition of room light and uses.The oblique view of the laptop PC of liquid crystal indicator of the present invention above illustrating, Fig. 6 is installed.The user shelves the laptop PC shown in the figure on the table and under the condition of room light, is that 30 ° and visual angle are that 0 ° mode is used it with the inclination angle.
Even at the indoor liquid crystal indicator that uses by this way, the incident direction of light generally still equals user's 90 ° at position angle.One 50 ° incident angle is arranged from the key light of light source (illumination).Hereinafter, will be as follows to the foundation of top those inclination angles, visual angle and incident angle.
10 people that use reflective LCD device have been carried out once investigation with regard to inclination angle and visual angle.When Fig. 7 illustrates actual use liquid crystal indicator to the measurement result at inclination angle and visual angle.As shown in the figure, most objects all are to be about 30 ° and visual angle with the inclination angle to use display device for+10 ° mode.
Generally, known from institute, the incident light in the office has the angle between 30 ° to 60 °.In order will directly to reflect at boresight direction from the incident light of the such light source of office, promptly satisfying directly reflection must be with+10 ° of visual angles reflection with the light of one 30 ° to 60 ° angle incident.
In this embodiment 2, this measurement result indicates, and reflective LCD device must be registered to from the manufacturing of the light of the display surface of 90 ° of user location incident liquid crystal cell near azimuthal direction of 1 by the contrast with the light of 30 ° to 60 ° degree incident is become.
Generally, 70 ° of (incident angle+reflection angle)=(30 ° to 60 ° of incident angles)+visual angle (± 10 °)=maximal values to minimum value is desirable for 20 °.
Because the reflecting surface pitch angle that is used for directly reflecting is (incident angle+reflection angle)/2, it is 10 ° to 35 ° so be used for the reflecting surface inclination angle of directly reflection.This shows, have reverberator that the reflecting surface in this scope tilts should with have one contrast be used in combination near 1 position angle liquid crystal cell.
Above described be the general user mode of display device.In the situation of special user mode, for example say that the patient on the sick bed that is in hospital uses the situation of liquid crystal indicator, inject direction and boresight direction both and be user side's parallactic angle of 0 °, display device itself is that horizontal positioned.
In this situation, 0 ° of azimuth direction of liquid crystal cell (its contrast become in 0 ° of orientation no better than 1) is by to living the promptly main incident direction of light of family, angle azimuth direction with 0 °.
In other words, desired azimuth direction is aligned to the horizontal direction of reflective LCD device, and so, incident optic angle, user side's parallactic angle and boresight direction all will change with the usage of used liquid crystal indicator.
Thereby, reflective LCD device of the present invention is by considering how to use display, produce liquid crystal cell with such visual angle dependence with draw for desired angle incident in the contrast in desired orientation near 1, and arrange liquid crystal cell to such an extent that make desired azimuth direction can aim at incident direction (when using display device) from main light source.
This exemplary embodiments is with the mode of 90 ° of user side's parallactic angles or the reflective LCD device that uses with the horizontal direction of the display surface of liquid crystal indicator.
In this embodiment 2, the reflecting surface normal tilts 10 ° to the direction of display surface normal, hereinafter, is defined as the reflecting surface pitch angle by reflecting surface normal to the degree of tilt of display surface normal.
Therefore, in this situation, the reflecting surface pitch angle is 10 °, and just in time shown in Figure 10 (b), the back will illustrate it to the sectional view of reverberator, and the manufacturing of reverberator is as described below.
Fig. 8 illustrates the shape of the icking tool that is used to make reverberator among the embodiment, and as shown in the figure, the pitch angle of icking tool end is 10 °, uses this icking tool that a brass sheet is carved into mould.
For the shape wearing and tearing of avoiding mould with become irregular, just be polished once for 300 times at icking tool per quarter, a kind of acrylic resin board is heated to press to above the glass transient point and with this mould and is used for the acryl resin of die forming.Then, the aluminium that evaporation 1000 are thick onboard is to make reverberator.
The laptop PC that liquid crystal indicator is installed above be used in be 580 indoor, this luminous environment also is placed among other embodiment, the brightness of the bright viewing area of contiguous dark viewing area is 35cd/m 2, and be 53cd/m away from the brightness of the bright viewing area of dark viewing area 2, the contrast of Qu Zhiqu is 1.5, shade is not obvious and visibility good.
Just as explained above, when using under the situation of the top of the light positive of office user fortunately, it is fixed by reflecting surface is tilted to 10 °, making can be in the direction reflection near the optical axis from the light of light source, and pass through 0 ° of azimuth direction of liquid crystal (for 30 ° of light to 60 ° of incidents, the contrast of liquid crystal cell becomes no better than 1 at 0 ° of position angle) be registered to user side's parallactic angle of 90 °, just obtain having the reflective LCD device of less shade and good visual degree.
Embodiment 3
In present embodiment 3, the reflecting surface of the liquid crystal indicator among the embodiment 2 tilts to have and is decided to be 25 °, makes and can directly reflect at boresight direction from the main incident of light source, that is to say, makes that directly the reflection requirement can be satisfied.
The brightness of the bright viewing area of contiguous dark viewing area is 57cd/m 2, be 75cd/m away from the brightness in bright demonstration Europe of dark viewing area 2The contrast of Qu Zhiqu is 1.3.Shade is so unobvious and visibility is good.
The reflecting surface pitch angle is decided to be 25 ° more effectively directly reflecting incident light at boresight direction, and contrast is almost become 1 direction is registered to light incident direction from the source to obtain the reflective LCD device that shade is few, brightness is high and visibility is good.
Embodiment 4
In present embodiment 4, the liquid crystal indicator that embodiment is 3 li is equipped with a phase plate, and its three axles have big or small mutually different refractive index n X, n Y, n Zn XBe the mean direction of liquid crystal molecule axle in this situation, the LCD among the embodiment 3 is used a n x=1.5864, n y=1.5829, and n z=1.5820 phase plate, n xWith n zMagnitude relationship be n x＞n z
Otherwise under the situation of phase plate, that take is n in the present embodiment x=1.5848, n y=1.5798, and n z=1.5843.In the phase plate of embodiment 3 and 4, n xAnd n zAlmost equal, and magnitude relationship all is n x＞n z, n YSize different in two embodiment.
The optical path difference of phase plate plane normal direction is all got same numerical value in two embodiment, illustrate down in the present embodiment 4 visual angle to the dependence of contrast of LCD degree.
Fig. 9 illustrates the orientation that is applicable to liquid crystal cell of the present invention and another embodiment of the relation between the contrast, and the situation of the liquid crystal cell in embodiment 4 when deflection is 0 ° and 180 °, obtains minimum contrast.
The situation of the liquid crystal indicator in embodiment 4, the brightness of the bright viewing area of contiguous dark viewing area is 60cd/m 2, and be 60cd/m from the brightness of the bright viewing area of dark viewing area 2, the contrast of Qu Zhiqu is 1.3, shade is so unobvious and visibility is good.
Just as explained above, even use the n of different sizes X, n YAnd n ZIf the direction of light incident is registered to the mean direction of liquid crystal molecule axle in the central core of liquid crystal layer, then can obtain a reflective LCD device that shade is few, brightness is high and visibility is good.
Embodiment 5
In present embodiment 5, the liquid crystal indicator among the embodiment 3 is equipped with a reverberator, and its reflecting surface that tilts into two kinds of patterns of 10 ° and 20 ° inclinations is alternately arranged.
The brightness of the bright viewing area of contiguous dark viewing area is 60cd/m 2, and be 83cd/m from the brightness of the bright demonstration of dark viewing area 2, the contrast of Qu Zhiqu is 1.4.Shade is so unobvious and visibility is good.
Because reflecting surface (every kind all has and the is different from alternative pitch angle) cloth of two kinds of patterns comes on the reverberator, so reverberator can effectively utilize the light that is installed in a plurality of light sources on the ceiling, for reflective LCD device provides high brightness and good visibility.
Embodiment 6
In present embodiment 6, the liquid crystal indicator among the embodiment 3 is equipped with a reverberator, and the reflecting surface that is inclined to two kinds of patterns at 15 ° and 25 ° pitch angle is alternately arranged thereon.Reflecting surface tilts selected according to following reason.
In a plurality of light sources that are installed on office's ceiling, measure the incident angle of two strong light sources of emission, the result equals 30 ° and 50 °, gets the pitch angle with these incident angles of 2 five equilibriums and 0 ° of angle (display surface normal).In other words, nearer stronger light directly reflects at boresight direction.
The brightness of the bright viewing area of contiguous dark viewing area is 65cd/m 2, and be 89cd/m away from the brightness of the bright viewing area of dark viewing area 2, the contrast of Qu Zhiqu is 1.4, shade is so unobvious and visibility is good.
Because reflecting surface (every kind all has and the is different from alternative pitch angle) cloth of two kinds of patterns comes on the reverberator, and each reflecting surface tilts all to arrange to such an extent that make two more close liquid crystal indicators and launches more that the luminous energy of the light source of high light directly reflects at boresight direction, thereby reverberator can effectively utilize the light that is installed in a plurality of light sources on the ceiling, and the reflective LCD device of high brightness and good visibility is provided.Certainly, also can use plural light source in this situation.
Embodiment 7
In present embodiment 7, the LCD among the embodiment 6 is equipped with the reverberator that a pressing mold is pressed into, and its surface is corroded into fine uneven to increase scattering of light.
Here, Fig. 1 will be used to illustrate the present invention again, if reverberator has a minute surface, scenery around it will reflect and user's face, this can hinder user's notice and concentrate on the display device, proposed an embodiment and solved this class problem, be i.e. a kind of method of use in one of light stroke by LCD light scattering.
If light is scattered, then be reflected on the display surface around scenery and user's face become ambiguous and be difficult to perceive, make the user be absorbed in display device.But in inclined to one side device 13 and the following polarizer 23, polarization must keep on light passes through.So light must scattering in other stroke.
Specifically, between following polarizer 23 and reverberator 31, rather than between last polarizer 13 and following polarizer 23, form a light scattering layer, and the surface of reverberator 31 is become a scattering layer by roughening.
The brightness of the bright viewing area of contiguous dark viewing area is 60cd/m 2, and be 95cd/m from the brightness of the bright viewing area of dark viewing area 2The contrast in district is 1.6, and shade is so unobvious and visibility is good.
Room light is not a pointolite, and angle of light is the scattering properties of passing through to increase reverberator of distributivity, from each incident angle that can be effectively used to of a plurality of light sources.And, since the unexpected variation of the surface brightness that visual angle change causes, the reflective LCD device that can obtain to have high brightness and good visuality.
Micro concavo-convex injustice on the display surface can also not only be formed by etching in addition, and by sandblast or by forming with the rough surface polishing.In addition, acid corrosion, sandblast or all can before AM aluminum metallization is handled, use on the resin plate, acid corrosion, sandblast or also all can use evaporation with the rough surface polishing and cross on the reverberator of aluminium with the rough surface polishing.
Scattering layer can be fine rough surface to be arranged or have the plastic sheeting that birefraction distributes.Plastic sheeting can also be placed on down between polarizer 23 and the reverberator 31 or stick on the surface of reverberator 31.
Embodiment 8
In present embodiment 8, liquid crystal indicator among the embodiment 3 is equipped with a reverberator, above it fine sags and crests arrangement pitches be 30 μ m be size less than 1/10 of a pixel, when from each the different optical axis observation display, do not produce moire and visibility is fine.Moire is meant how much band figures as woven design.
The sectional view of reverberator of the present invention is for example said as shown in figure 10.Reverberator shown in Figure 10 has a reverberator that is not parallel to display surface.For the reflection coefficient that makes reverberator seems uniformity, the size of roughness must reduce as far as possible on the reflecting surface.Thereby if the distance between the adjacent salient point becomes a spacing surely on the reflecting surface of reverberator, then this interval maximum also must be less than a pixel.
Moreover if the size of pixel and recessed/bump size are periodically overlapping, then moire occurs.If go out moire, show just to become unbalanced, cause visibility to descend.
This, moire changes with the change of the optical axis to a great extent.In this situation, the visibility loss is great, and the scrambling of the spacing on the reflecting surface is for preventing that this class moire from will be effective.The sentence talk about, spacing should be less than a pixel, its size can be less than 1/5 of a pixel.
Embodiment 9
In present embodiment 9, the liquid crystal indicator among the embodiment 3 is equipped with a reverberator that the local surfaces embayment is curved, when using liquid crystal indicator, always requires the variation of the show state that the change of user's optical axis causes to be reduced to minimum.
In liquid crystal indicator of the present invention, if the optical axis on the opposite that incident is directly reflected, high brightness shows it is possible.But if the optical axis moves that I guess little by little, then brightness sharply reduces.Thereby big if the optical axis changes the variation of the show state that causes, then the purposes of liquid crystal indicator is restricted.
Usually, reduce to minimum, adopt a kind of method that makes usual reflector possess the light scattering function for the optical axis being changed the reflection characteristic variation that causes.
But, at liquid crystal indicator the situation of a polarizer is only arranged, owing to this light scattering function produces a problem.For avoiding this point, also to use a method to come curved reflective surface.Figure 10 (g) illustrates a kind of like this sectional view of reflecting surface to Figure 10 (i).
Figure 11 illustrates the icking tool shape of the reverberator that is used to make another embodiment.
Manufacturing with reverberator of a curved surface can for example say that icking tool (its cross section bends to as shown in figure 11) carves a sheet metal (brass or the like) and make mould and come mold pressing acryl resin or the like and will be such as the metal evaporation of aluminium or the like to the surface by using.
Figure 12 illustrates how to use LCD in office, also shows the direction that the light that is contained in a plurality of light sources on the ceiling enters the reflective liquid-crystal display of using.In office, a plurality of light sources are lined up picture (L on ceiling 1, L 2, L 3...), if these light sources all use as light, the brightness of display surface just can further improve.
Moreover, curved if partially reflecting surface is an embayment, just can will guide the user into from the light of multiple source, Figure 13 shows the sectional view of the reflector characteristic of explanation partially reflecting surface bending.
In other words, have the reverberator of flexure plane as shown in the figure, near the P point, reflecting surface normal bisection L 1Direction and user side are to, L 1Be drawn towards the user.Equally, near 9 o'clock, reflecting surface normal bisection L 2Direction and user side to.L 2Light be drawn towards the user equally in present embodiment 9, partially reflecting surface is crooked.The xsect of reverberator is as shown in Figure 10 (g).Phantom shaft among Figure 14 shows the vertical view of reverberator microcosmic.One end of reflector surface sweep tilts 30 ° and the other end tilts 10 °.For example, suppose have many in 60 ° and 20 ° of scopes the light source of emission light.
The reflection horizon is by following manufacturing: have the icking tool of curved surface as shown in figure 11 to carve a brass sheet with the top.Curved surface shown in Figure 11 is near elliptical area.Used cutter with 100 μ m radiuses and 50 μ m radiuses.Every usefulness 200 less important grindings of icking tool are to prevent that its reflective surface is owing to loss is out of shape.After this, brass sheet is used as mould in embodiment 2, come the acrylic resin board of a heating of mold pressing.Then, the thick aluminium of evaporation 2000 on resin plate.
The brightness of the bright viewing area of approaching dark viewing area is 51cd/m 2, and be 69cd/m away from the brightness of the bright viewing area of dark viewing area 2The contrast in two districts is 1.35.Shade is not clearly, and visibility is good.
The local reflex laminar surface is crooked, and the reflecting surface pitch angle is to distribute like this, so that the light incident direction and the formed angle of boresight direction that halve by the stronger light source of many more close liquid crystal indicators and intensity can be comprised.
Moreover, from the light of a plurality of light sources by directly along the boresight direction reflection, perhaps with conditioned reflex, thereby can effectively utilize, so that the reflective LCD device with high brightness and good visibility to be provided from the light of those light sources near this.
Embodiment 10
In present embodiment 10, liquid crystal indicator has been provided a plate by making with epoxy resin bonding reverberator 31 and subtegulum 22.The refractive index of epoxy resin is about 1.5.Therefore, if consider the anaclasis that produced by epoxy resin, the pitch angle of reverberator is necessary for 17 °, directly reflects light with 50 ° of angle incidents along boresight direction.In the present embodiment, by this way rather than the mode of the use among other embodiment obtain reverberator to obtain 17 ° of pitch angle.
The brightness of the bright viewing area of approaching dark viewing area is 74cd/m 2, and be 60cd/m away from showing slinkingly the brightness of bright display part of showing part 2The contrast ratio in two districts is 1.2.Shade is not clearly, and visibility is good.
Even it is verified when with epoxy resin reverberator 31 and subtegulum 22 being combined as a whole as mentioned above, if consider the refractivity coefficient of epoxy resin desirable value is arranged at the pitch angle of reflecting surface, have many methods can obtain to have with embodiment 3 in the liquid crystal indicator reflective LCD device of display performance much at one.
If have resin or other similar substance that equates refractive index with following polarizer 23 compiling down to fill between light device 23 and the reverberator 31, can prevent minimizing by light intensity.
Embodiment 11
In present embodiment 11, liquid crystal display is as shown below.The also liquid crystal indicator shown in other embodiment.
Fig. 2 shows the xsect of liquid crystal indicator among another embodiment.Liquid crystal indicator shown in Fig. 2 comprises from the superimposed in order following part of display surface: go up polarizer 13 for one, a phase plate 19, go up substrate 12 for one, 14, one of a top electrode is gone up 11, one liquid crystal layers 10 of oriented layer, a following oriented layer 21,24, one reverberators 31 of a bottom electrode, and a subtegulum 22.
Different with the liquid crystal indicator shown in Fig. 1, in this liquid crystal indicator, following polarizer sheet 23 has been omitted, and reverberator 31 is placed on the subtegulum 22, and the position of reverberator 31 and subtegulum 22 has become.Moreover reverberator 31 and subtegulum 22 generally are combined as a whole.Therefore, subtegulum 22 can be made without glass.In other words, other part, material and manufacture method all with embodiment 1 in the same.
Have reflecting surface and with subtegulum be combined as a whole reverberator by following manufacturing.
Figure 15 (a) shows an embodiment who makes reverberator of the present invention to 15 (d).
To explain how to make reverberator below.The substrate of a glass material is carved into the reverberator 31 (Figure 15 (a)) with shape as shown in Figure 10 (b).The reflecting surface pitch angle is 20 °, and the spacing of reverberator epirelief top and trench is 20 μ m.At this moment, the bump height of the uneven surface of reverberator is 4 μ m.
Then, at the thick lead of surperficial evaporation 1000 of reverberator 31, form reflection horizon 41 (Figure 15 (b)).Make this smooth surface by on reflection horizon 41, forming the thick epoxy resin smooth layer 53 of 20 μ m.Afterwards, the surface of epoxy resin layer is made it smooth (Figure 15 (c)) by throwing.At last, shown in Figure 15 (d), form bottom electrode 24 and following oriented layer 21.
Reverberator can have the diffraction grating of xsect Any shape as shown in Figure 10 (a) to (c), pyramid or the like.In present embodiment 11, the substrate that forms reverberator can not pass through light, so can also extensively select material except glass.Do not resemble the hard like this material of glass owing to do not need to cut, so be easier to make.
Liquid crystal indicator among the embodiment 11 is installed on a kind of (lap-top) on knee PC, and uses under indoor light.The user is put liquid crystal indicator on the table, and uses at most in the mode at 30 ° of pitch angle and 0 ° of visual angle.In this case, from the light of light source with about 40 ° angle incident display device.
In the reverberator in being comprised in liquid crystal display, the brightness of the bright viewing area of close dark viewing area is 60cd/m 2, and be 61cd/m away from the brightness of the bright viewing area of dark viewing area 2The contrast ratio in two districts is 1.0.Can not distinguish to show slinkingly and show shade.The brightness of dark viewing area is 9cd/m 2, contrast is 7.
Just as already explained, because reverberator is bonded among the liquid crystal cell, and incident ray directly reflected at the condition lower edge at 20 ° reflecting surface inclination angle boresight direction, and the reflective LCD device that can obtain to have fabulous visibility is distinguished and misknowed shade and contrast height.
Embodiment 12
In present embodiment 12, liquid crystal indicator has utilized the reverberator of being furnished with 20 ° of reflecting surface inclination angles and making with straightforward procedure.It is anti-that Figure 16 (a) shows manufacturing the present invention to Figure 16 (e). penetrate another embodiment of device.To straightforward procedure that make the reflection horizon be described at first.
At first, on subtegulum 22, form a resin bed (Figure 16 (a) with acryl resin.This layer is heated and uses the mould mold pressing, to produce its shape reverberator 31 of (Figure 16 (b)) just as shown in Example 11.Then, in surperficial AM aluminum metallization to form reflection horizon 41 (Figure 16 (c)).
After this, in Figure 15, form a smooth layer 53 concavo-convex to eliminate (Figure 16 (d)), and form bottom electrode 24 and following oriented film 21 (Figure 16 (e)).In Figure 16 (b), the mold pressing that is used to be shaped can replace with the graduating with cutter operation.
Use subtegulum 22 among the embodiment 11 and last substrate 12 both the time, an available in the same old way manufacture method.Manufacture method just as shown in Figure 15 need not cut by resembling the subtegulum 22 that the such stiff materials of glass is made, so be easy to make reverberator 31.And, can obtain having fabulous visibility and high-contrast, and shadeless reflective LCD device as among the embodiment 11.
Embodiment 13
In present embodiment 13, use a kind of reverberator of reflecting surface of two kinds of patterns that 15 ° and 25 ° inclination angles are housed, the reflecting surface of these two kinds of patterns alternately to be arranged on the reverberator with the straightforward procedure manufacturing at the liquid crystal indicator shown in the embodiment 12.It is used to replace the reverberator with 20 ° of face inclination angles of employing among the embodiment 12.
The brightness of the bright viewing area of close dark viewing area is 55cd/m 2, and be 55cd/m away from the brightness of the bright viewing area of dark viewing area 2The contrast in two districts is 1.0.Distinguish to misknow to show slinkingly and show shade.The brightness of dark viewing area is 8cd/m 2, contrast is 7.
As mentioned above, because reverberator is bonded among the liquid crystal cell, and having the reflecting surface arranged alternate of two kinds of patterns of different angle, the boresight direction that two incident raies are roughly continued to use the family directly reflects, so can obtain to have the reflective LCD device of fabulous visibility.Distinguish and misknow shade and contrast height.
Embodiment 14
In present embodiment 14, liquid crystal indicator has as shown in Example 12 used the reverberator of a kind of part as bending, by the short-cut method manufacturing and 20 ° reflecting surface inclination angle is provided.Used with embodiment 9 in equiform mould come die forming.
The brightness of the bright viewing area of close dark viewing area is 52cd/m 2, and be 52cd/m away from the brightness of the bright viewing area of dark viewing area 2Can't see shade.Showing slinkingly the brightness of showing part is 7cd/m 2, contrast is 7.
Local for the reverberator of curved surface is bonded in the liquid crystal, and the reflecting surface tilt profiles gets and can comprise by bisection by the incident light direction of two light sources of more close liquid crystal display and the angle that boresight direction forms.
Since from the light of two light sources arc reflected directly into the user the optical axis or with this near conditioned reflex that is coupling, therefore can be effectively utilized to reflective LCD device from the light of two light sources of ceiling provides high brightness and good visibility.
Embodiment 15
Fig. 3 shows the xsect of liquid crystal indicator in another embodiment of the present invention.In structure shown in Figure 3, only a color filter is added in the structure shown in Fig. 2.
In present embodiment 15, on subtegulum 22, form the reverberator 31 of the reflecting surface that has 20 °.In other words, the same just as in embodiment 11, following polarizer 23 has been saved, and reverberator 31 and subtegulum 22 have changed the position.In such liquid crystal indicator, color filter 50 is formed between substrate 12 and the liquid crystal layer 10.
The brightness of bright viewing area is 30cd/m 2, and the brightness of dark viewing area is 4cd/m 2The contrast in two districts is 7.Bright (in vain) display brightness and contrast are enough.Visibility is also fine.
As explained above, owing to omitted time polarizer 23, reverberator is formed on the subtegulum 22, does not pass lower floor 22 from the light of light source.Therefore, incident light and the problem of reflected light have been solved through different color filters.Moreover, because the reflection horizon with 20 ° of reflecting surface inclination angles is bonded among the liquid crystal cell satisfying the directly requirement of reflection, thus the compensation of the brightness that the light absorption of color filter is increased, thus provide good visibility for bright reflection color liquid crystal display.Color filter 50 also can be placed between subtegulum 22 and the liquid crystal layer 10.In other words, clearly, or even color filter 50 is placed in any position between substrate 12 and the reflection horizon 31, also obtains effect same.
In the structure of the liquid crystal indicator shown in the embodiment 15, even two color filters are color of the same race, light always is absorbed twice if light passes through this twice of two color filter.Therefore, in order to increase brightness.The transmitted spectrum of color filter itself should increase.Illustrate an example of these color filter transmitted spectrums down.
Figure 17 shows an example of red, green and blue color filter transmitted spectrum, and the transmissivity of color filter is high.In each visible wavelength region, any one transmissivity all is more than 10% or 10% in those red, green and blue color filters.
Embodiment 16
In present embodiment 16, used its curved reflective surface to be shaped as the reverberator that resembles a semicircle at the liquid crystal indicator shown in the embodiment 15.At first use semicircle icking tool with graduating with cutter operation only once, make the icking tool that is used for mfg. moulding die with 80 μ m radiuses.
The brightness of the bright viewing area of close dark viewing area is 49cd/m 2, and be 68cd/m away from the brightness of the bright viewing area of dark viewing area 2The contrast in two districts is 1.39.Shade be difficult to discover and the visibility of liquid crystal indicator fine.
Bright (in vain) brightness of viewing area is 25cd/m 2, and the brightness of dark viewing area is 4cd/m 2The contrast in two districts is 7.Bright display brightness and contrast all are enough.
In order to make its reflecting surface is crooked reverberator, must at first make its xsect and be the icking tool of curve as shown in Figure 11.If use the rotary machine such as lathe, curved surface is easy to make.
Yet in this case, the xsect of mach curved surface will become local arc simultaneously.As shown in Figure 16, if the curve form of reverberator is single semicircle, manufacturing will become and be easy to.
Moreover because reflecting surface is a curved surface as semicircle, so be easy to make the icking tool that is used for mfg. moulding die, also being easy to regrinds is used to carve the icking tool of brass sheet.
On the other hand, Figure 18 shows the viewing angle characteristic of the bright demonstration of liquid crystal indicator shown in embodiment 15 and 16.The brightness and the relation between the angle of incidence of light (angular dependence (-dance)) of bright display surface have been this figure also illustrates.
In the figure, transverse axis is represented the angle of incidence of light of definition among Figure 20 (b).The position angle is 90 ° or 270 ° as definition among Figure 20 (b).In embodiment 15, only can obtain high brightness near 0 ° of incident angle, and in other incident angle, then brightness falls sharply.
Under the situation of the liquid crystal display of in embodiment 16, adopting, near 15 ° of incident angles, all can obtain height.Even when user's the optical axis changed, the brightness of bright viewing area did not reduce much yet.Even also guarantee high brightness owing to the user has changed posture, so visibility is fine.
Next, the polarization and unpolarized will the explanation of the liquid crystal cell that comprises a polarizer shown in Fig. 2 and Fig. 3, to be interpreted as the reason that each reverberator that what uses has a minute surface respectively in embodiment 11 to 16.
Usually, a liquid crystal indicator utilizes liquid crystal layer to receive polarized light, and comes modulating polarization by apply a voltage on liquid crystal layer.Therefore, inciding and from the liquid crystal indicator reflex time, light is through twice of polarizer.Natural light is exactly a polarized light through polarizer for the first time.
If the light through polarizer also is polarized light for the second time, the optical transmission rate changes with the voltage that is applied, and shows to distinguish bright demonstration and to show slinkingly.
Yet if the light of process polarizer is nonpolarized light (natural light, scattered light or the like) for the second time, the transmissivity of light does not change with applying voltage.As a result, in bright demonstration and show slinkingly and difference do not occur between showing.
If owing to certain reason, at light during for the first time with for the second time by polarizer, polarization disappears and has entered nonpolarized light, and then bright demonstration and the difference that shows slinkingly the light transmission between showing descend.
Under the situation of liquid crystal indicator shown in Fig. 2 and Fig. 3, light reflects on reflecting surface, and it passes through polarizer 13 for the first time when incident simultaneously, and passes through this sheet when coming out for the second time.Therefore, if reflecting surface is coarse, the scattered light that reflects with different angles mixes with polarized light, thereby becomes nonpolarized light.
In order to keep polarization after reflection, reflecting surface should be very level and smooth.Here it is only be furnished with the reverberator of the reflective LCD device of a polarizer why should very level and smooth reason.
Reference examples 1
In this reference examples 1, manufactured liquid crystal indicator has used among the embodiment 1 element that forms, and has contrast shown in Figure 25 and angle relation curve, thereby is maximal value to the light contrast with 90 ° of position angle incidents.In other words, in use, 0 ° of azimuthal direction is consistent with the horizontal direction of liquid crystal indicator.
Just the same among all the other and the embodiment 1 comprises a plate reverberator that its reflecting surface is parallel with display surface.
The portable data assistance that above-mentioned liquid crystal indicator is housed on it is in outdoor application.The brightness of the bright viewing area of close dark viewing area is 17cd/m 2, and be 73cd/m away from the brightness of the bright viewing area of dark viewing area 2The contrast in two districts becomes 4.3.Shade is easy to discover, and the visibility of liquid crystal indicator is bad.
As explained above, this proof is used a plane sheet reflector, and in other words, the reflecting surface normal direction is consistent with the display surface normal direction, and the direction of adjusting between the incident light bobbin and the optical axis is not enough to reduce shade and the visibility that obtains.
The visibility of becoming reconciled for the shade that obtains to be difficult for discovering, should adopt main incident light selectively, 0 ° of azimuth direction of the liquid crystal cell of (under this visual angle contrast become approach 1) correlativity so that make and to have the visual angle can be perpendicular to liquid crystal indicator in use.This means that 0 ° of azimuth direction can be consistent with the incident light direction.
Reference examples 2
In this reference examples 2, the reflecting surface inclination angle of reverberator is set to-20 ° among the embodiment 2, and LCD is placed and makes the reflecting surface normal direction not between incident light bobbin and user's the optical axis.
This liquid crystal indicator is positioned on the laptop personal computer, and uses under indoor light.The brightness of the bright viewing area of close dark viewing area is 3cd/m 2, and be 16cd/m away from the brightness of the bright viewing area of dark viewing area 2The contrast in two districts is 5.3.Whole screen is dark, shade be easy to discover and the visibility of LCD bad.
As explained above, this proof incident direction is consistent with required azimuth direction to be obtained and more approaches 1 contrast and be not enough to the visibility that improves the brightness of demonstration and obtain to get well.
In order to reduce shade and to obtain the visibility that high brightness is become reconciled, incident light should be introduced by the azimuth direction that obtains more to approach 1 contrast, also the reflecting surface inclination angle to be placed to such an extent that make the reflecting surface normal direction can enter between incident axle and user's the optical axis requirement that As soon as possible Promising Policy directly reflects.
Reference examples 3
In this reference examples 3, the reflecting surface inclination angle of reverberator is set to-25 ° and-10 ° among the embodiment 6, and liquid crystal indicator is placed the reflecting surface normal direction can not be entered between incident light axis and user's the optical axis.
This liquid crystal indicator is installed among the laptop personal computer and under indoor light and uses.The brightness of the bright viewing area of close dark viewing area is 3.1cd/m 2, and be 15cd/m away from the brightness of the bright viewing area of dark viewing area 2The contrast in two districts is 4.8.Whole screen is dark, shade be easy to discover and the visibility of LCD bad.
As explained above, if this proof liquid crystal indicator is placed the reflecting surface normal direction is not entered between incident light and user's the optical axis, in other words, if directly reflection requires not satisfy, even import along irradiation (beat-ing angle) direction that is more approached 1 contrast at incident light, also be not enough to obtain the visibility that high brightness is become reconciled.In order to reduce shade and to obtain the visibility that high brightness is become reconciled, directly reflection requires seemingly very important.
Reference examples 4
This reference examples 4 has been chosen the liquid crystal indicator among the embodiment 3, and one of them color filter 51 is formed between substrate 12 and the liquid crystal layer 10.
This liquid crystal indicator is contained in the laptop personal computer and goes up and use under indoor light.The brightness of bright viewing area is 3cd/m 2And the brightness of dark viewing area is 2cd/m 2The contrast in two districts is below 2.
In other words, though the reflecting surface inclination angle be set to 25 ° and directly reflection require to satisfy, brightness falls sharply and whole screen looks like that coal is equally black.
This proof only between last substrate 12 and liquid crystal layer 10 the colour demonstration of a formation color filter 51 pairs of reflective LCD devices be not enough.
In other words, satisfy directly reflection by sloping reflecter and require to be not enough to solve incident light and the problem of reflected light through different color filters, thereby, also not all right concerning reflection color liquid crystal display.
Reference examples 5
This reference examples 5 has been chosen the LCD of using among the embodiment 15, and wherein reflection horizon 31 is omitted, and a plane sheet reflector is formed on the subtegulum 22.Plane sheet reflector is by following manufacturing.Direct AM aluminum metallization forms the thick epoxy resin layer of 2 μ m thereon then as insulation course on subtegulum 22.And then, form bottom electrode 24 and following oriented film 21 in the above.
This liquid crystal indicator is installed on the laptop personal computer, and uses under indoor light.The brightness of bright viewing area is 12cd/m 2And the brightness of dark viewing area is 7cd/m 2The contrast in two districts is below 2.
Owing to saved time polarizer 23 and subtegulum 22 is formed at below the reverberator 31, so solved the problem that incident light and reflected light pass through different color filters.Yet, because reverberator is dull and stereotyped so direct reflection requires not satisfy.The brightness and contrast is all low and visibility is bad.
This proof shows that for the colour of reflective LCD device not only reverberator should be combined among the liquid crystal cell, and should satisfy direct reflection requirement and suitably select light source (promptly selecting main light source light for use).
According to the present invention, solved shade and these outstanding issues of low-light level in the conventional reflective liquid crystal indicator, and can obtain to have the reflective LCD device of good visual degree.
Particularly, can realize that for obtaining the colored reflection type liquid crystal that shows of high brightness shows that the present invention is effectively.
Will be according to another reflective LCD device of the present invention following by being described in detail with embodiment.
Below Xu Shu embodiments of the invention have structure as shown in Figure 28, and below will be according to the structure narration of Figure 28.
Embodiment 17
Soda-lime glass is used as transparent substrate 12 and following transparent substrate 22.Each forms on substrate 12 and 22 with matrix electrodes that ITO constitutes, as powering on 5 and bottom electrode 24.Each electrode is wide to be 0.3mm, and 0.03mm and thickness are 1000 at interval.Number of scanning lines be 480 and the signal wire number be 640.
On-chip oriented layer 6 and 10 is made by polyimide polymer, it toasts under 200 ℃ of temperature, in cutting output is that 0.4mm, rotating speed are 1000rpm and advance under the condition that network speed is 33m/sec and stand an orientation process by rubbing manipulation (rubbing method), afterwards, under 150 ℃ of temperature, carry out an ageing process.Thereby top rake (pre-tiltangle) is 4 ° and torsion angle is 240 °.
Liquid crystal layer 21 is to be made by the pneumatic liquid crystal (pneumatic liquid crystal) and the potpourri of chiral dopant.The MJ63928 (trade name) that is made by Japanese firm (Merck Japan Ltd) is used as liquid crystal material, and the △ n under state in bulk is 0.145.The S811 (trade name) that is made by Japanese firm (Merck Japan Ltd) is used as chiral doping reagent, and weight content number percent is 0.9%.
By changing thickness, its △ nd (the birefringence △ n of liquid crystal material and thickness of liquid crystal layer d's is long-pending under state in bulk) is respectively 0.755 μ m, 0.812 μ m, and the liquid crystal cells of 0.843 μ m and 0.858 μ m is manufactured.
Phase plate 7, polarizer 8 and 11 and beam reflector combine with each liquid crystal cells, thereby form reflective LCD device.
The G1225DU (trade name) that is made by Nitor (Nitto Denko Co.) is used as upper and lower polarizer, and the polycarbonate phase plate of being made by same company is used as phase plate.
Although above-mentioned flash type reverberator is used as beam reflector, during with such beam reflector, if the reflection horizon is good even surface, the user can see the reflection of light source under this situation.The part brightness of seeing the light source reflection is very high, and other parts then brightness are low, changes thereby brightness takes place on image screen.
In order to obtain all even bright display screen in the present embodiment, thereby also used each reflecting surface that the jog reverberator that forms many small reflectings surface on reflecting surface is as shown in Figure 29 all arranged.
Because the reflecting surface angle difference of small reflecting surface, the light that enters from different directions quilt shown in dotted line reflects equably to the user.Thereby the reflection of light source loses its outline line, is evenly diffused throughout on the screen, therefore obtains to have the even demonstration of high brightness.
Such reflective LCD device is with over against according to the running of formula display packing, and wherein shade is presented at two or more high voltage one sides that apply among the voltage and carries out.
When the optical condition of phase plate and polarizer is an optimum value when satisfying the characteristic in colourless in according to the formula display packing, high-transmission rate and high-contrast, the combined number of the optical condition of phase plate and polarizer is a very big numeral, and will spend the plenty of time for obtaining an optimum value by test and correction.
Therefore, in the present embodiment, optical condition is the optimum value in the displaying principle of having considered liquid crystal indicator.
Determine the position angle of liquid crystal display and the elevation angle as shown in Figure 34.
The direction of dividing equally in the orientation process direction of the upper and lower oriented layer of liquid crystal display is 0 °.From when display surface direction is rearwards observed, counterclockwise define the position angle.Be defined as the elevation angle with the angle of the normal of substrate plane.
Angle between the direction of the orientation process that descends polarizer 11 and following oriented layer 10 should equal about 45 °.
Liquid crystal indicator shows in conjunction with the method that changes polarization state of transmitted light by using change to apply voltage.The change of polarization state depends on the polarized state of light of incident liquid crystal layer, in other words, depends on down the angle of the absorption axes of polarizer.
If when setting angle between the direction of the absorption axes of polarizer and following oriented layer orientation process and being a, then when angle a when 40 ° to 50 ° scopes preferably equal 45 °, polarized condition change into maximal value.
When the torsional direction of liquid crystal layer is decided to be left and torsion angle when being θ, owing to equal (θ along the position angle of the direction of oriented layer orientation process down ... 180 °)/2, the position angle of following polarizer absorption axes represent by expression formula (23):
θ/2+90°-α(40°≤α≤50°………(23)
Enough steep and generation is provided with the torsion angle of the voltage-transmission characteristics of hysteresis.In 200 ° to 270 ° scope.Descend the orientation of the absorption axes of polarizer in this case, in 140 ° to 185 ° scope.
The orientation of the light path deviation shaft of phase plate by as make decision.
Because in present embodiment of the present invention, phase plate is arranged between liquid crystal cell and the last polarizer, thereby phase plate changes the polarized condition by liquid crystal layer light.
In order to improve contrast by reducing transmissivity when shade shows, each has the light that enters the polarizer wavelength must be by using phase plate to convert the wherein the same linear polarization of direction of vibration to.
As described in " the 9th international show research minutes " the 312nd to 315 page, expressed a kind of by using Pu'an card thunder ball that the position angle of slow axis of phase plate and the method for optical path difference are set.
Pu'an card thunder ball is meant to have fuel parameter (S 1, S 2, S 3) be 1 ball as the radius of three axles, each polarization state corresponding on the card thunder ball of Pu'an a bit.For example, a linear line polarization is corresponding to one and plane (S 1, S 2) straight line of quadrature.
By following expression, utilize the component E of X-axis X, the component E of Y-axis Y, and E XAnd E YComponent differ δ, determine the fuel parameter in this example.
S 1=(E X 2-E Y 2)/(E X 2+E Y 2)……(24)
S 1＝2E XE YCosδ/(E X 2+E Y 2)……(25)
S 3＝2E XE YSinδ/(E X 2+E Y 2)……(26)
The conversion of phase plate polarization state is crossed by pile warp and is included in parameter (S 1, S 2) the straight line rotation expression at the center of Pu'an card thunder ball in the plane.Polarization state by phase plate is converted into the face of being projected in (S 1, S 2) on Pu'an card thunder ball in the line position claim.
Be projected in plane (S at Pu'an card Lei Qiuzhong as the straight line of rotation center 1, S 2) on the position angle, be phase plate Slon axle) azimuthal two ones.Utilize wavelength X and optical path difference △ nd, rotation angle can be expressed as =2 π △ nd/ λ (unit is a radian).
Figure 30 shows an example by the polarization state of liquid crystal layer wavelength of light, and wherein a high voltage is applied in to liquid crystal layer among two or more apply voltage.
Figure 30 shows one and is projected in face (S 1, S 2) on Pu'an card thunder ball.Characteristics are that the point of the polarization state of expression wavelength almost is a linear distribution.
By utilizing the distribution character of each wavelength polarization state, slow axis of phase plate (slowasix) and optical path difference can determine as shown in Figure 31.
Figure 31 show with Figure 30 similar manner at face (S 1, S 2) go up the Pu'an card thunder ball of projection.At first, a straight line through the point of great majority expression wavelength polarization state, promptly a tropic is drawn by with dashed lines and represents.
With the tropic intersect vertically line azimuthal half, become the orientation of the slow axle of phase plate, following expression:
180°-θ/2………………………(27)
In the scope of above-mentioned torsion angle, the position angle is in 45 ° to 80 ° scope.
Moreover the tropic is also represented the direction of motion that each represents the point of wavelength polarization state.
Transmitted light with 550nm wavelength is noted that this wavelength is a maximal value to people's visibility.When the optical path difference of phase plate was decided to be about 380nm, the point that expression has 550nm wavelength polarization state of transmitted light was moved to and face (S 1, S 2) on the straight line that intersects a bit (Figure 31 mid point A).In other words, be converted into linear polarization.
Transmitted light with other wavelength is converted into each and has polarization state with top same polarization state substantially.
The absorption axes of last polarizer is located at half of Figure 31 mid point A orientation.Owing to go up polarizer in this example the absorptivity of transmitted light with 550nm wavelength is maximum, so the transmissivity when shade shows reduces, and contrast is improved.
Under the situation of angle in 40 ° to 50 ° scope between the direction of the absorption axes of last polarizer and following oriented layer orientation process, the position angle that A is ordered obtains to be (350 °-2a-θ) by experiment.Thereby the position angle of last polarizer absorption axes can be expressed as follows:
175°-a-θ/2…………………(28)
In above-mentioned torsion angle scope, the position angle of the absorption axes of last polarizer is among-10 ° to 35 ° scope.
The optical path difference of phase plate by the position angle of the light path deviation shaft of the position angle phase plate of the following polarizer absorption axes of determining as mentioned above and in the position angle of polarizer absorption axes, all change, and the time along the bright demonstration of liquid crystal display substrate plane normal direction, the no colourity of transmitted spectrum can be by using the wherein well-proportioned UCS system of chromatic coordinates estimation of aberration.
Suppose the coordinate (U of illuminant-C 0=0.201, V 0=0.460) for colourless fully.Colourless degree W is by using the distance with the illuminant-C coordinate to be determined by following formula. W = [ ( U - U 0 ) 2 + ( V - V 0 ) 2 ] … … ( 29 )
Need not say that transmitted spectrum diminishes along with W and becomes colorless.
Relation between the optical path difference of colourless degree W and phase plate as shown in Figure 32.Very clear from Figure 32, when optical path difference is in the scope of 320nm to 420nm the time, colourless degree W equals 0.02 or still less, thereby has obtained the colourless state of enough transmitted spectrums in the substrate face normal direction.
Because contrast is 10: 1 or bigger in this scope, and the transmission ratio when bright the demonstration is 28% or bigger, and much less, contrast and transmissivity have fully satisfied desired properties.
Moreover the △ nd (the △ n of state liquid crystal material in bulk and thickness of liquid crystal layer d's is long-pending) by changing liquid crystal layer can measure colourless degree W.Therefore, as shown in Figure 33, obtained and when any △ nd, equaled 0.02 or colourless degree W still less.
As the above mentioned, become colourlessly along the transmitted spectrum of substrate face normal direction, and obtained high-transmission rate and high-contrast.
Narration now makes along the transmitted spectrum of light incident direction and becomes colourless a kind of situation.
At first consider the environment for use of reflective LCD device, and regulation light incident direction.
Suppose it is the situation of using reflective LCD device in office, light is penetrated from the top usually.The user extremely to a certain degree uses it by the inclined reflection-type liquid crystal indicator.
In this example, the position angle is logical to be made as 0 ° in the horizontal direction, thereby visual angle characteristic is in left-right symmetric, and the inclination angle is set to, for example, and 30 °.
A plurality of lamp decorations on the ceiling are light sources of such state, and promptly the position angle of light incident direction is about 90 °, and the elevation angle is about 30 ° to 60 °.
In the occasion that reflective LCD device uses under non-office condition, for example, reflective LCD device is contained in when also using outside on the portable data assistance, and it is same direction substantially that the incident light direction is considered to.
When colourless degree W is 0.04 or still less the time, can feel show almost colourless.
On the other hand, shown in expression formula (22), because the Show Color of reflective LCD device, be that transmitted spectrum during by light incident determines with the long-pending of transmitted spectrum at the light reflex time, even colourless degree W is 0.04 or still less, at them both predominant wavelength near the time, colourity increases the weight of and the long-pending colourless degree W of two transmitted spectrums surpasses 0.04.
Therefore, be at present embodiment, in addition under the wavelength of light incident and light reflex time transmitted spectrum is preponderated situation, prevent colouredly, search out a kind of condition, any one colourless degree W of all spectrum all equals 0.02 or still less under this condition.
For at the transmitted spectrum that the substrate face normal direction is bright when showing, W=0.003.
For phase plate 7, if phase plate is made as n in the refractive index of two electronoptical main axis (quadrature in a plane) direction xAnd n y(n X＞n Y), and the refractive index of phase plate thickness direction is made as n zThe time, determine the eigenwert n3 of phase plate by following equation (30), that is:
n 3=(n z-n x)/(n y-n x)……(30)
Use (30) and pass through to change eigenwert n 3, can measure the colourless degree W of incident light transmitted spectrum.Thereby drawn in the result shown in Figure 35.
In other words, as the eigenwert n of phase plate 3Be timing, the W value is big, and the predominant wavelength of transmitted spectrum is approximately 605nm, is almost brown.
Thereby the index ellipsoid in this example looks like rugby as shown in Figure 36.
As eigenwert n 3When reducing, the W value also reduces.At eigenwert n 3Be 0.3 or littler zone in, W is 0.02 or littler.Transmitted spectrum is almost colourless in this zone.
Index ellipsoid in this example is a circle lens shape as shown in Figure 37.Though do not understand in Figure 37 to illustrate that it has been expected semisphere.
Therefore, in the present embodiment, phase plate 7 is constructed by this way, by the definite eigenwert n of expression formula (30) 3Be 0.3 or littler, thereby make the transmitted spectrum of LCD simultaneously colourless in light incident direction and light reflection direction.
Notebook PC according to the reflective LCD device of embodiment 21 is housed, is placed on office's table with 30 ° of inclination angles.Show state system is observed from the plane normal direction of liquid crystal indicator.
Polarizer and phase plate place under the optical condition in the scope as mentioned above, in other words, in Figure 28, the position angle of the absorption axes of last polarizer 8 is 20 °, the position angle of the absorption axes of following polarizer 11 is 165 °, the optical path difference of 7 pairs of 550nm wavelength of phase plate equals 380nm, the axle (slowaxis) the position angle be 60 °, thereby and eigenwert n3 equal 0.01.
As a result, liquid crystal indicator is respectively 0.010 and 0.010 in the colourless degree W of the transmitted spectrum of light incident direction (position angle be 90 ° and the elevation angle is 30 ° to 60 °) and light reflection direction (elevation angle is 0 °).
Show state during bright the demonstration is almost colourless.In this example, surface brightness is 65cd/m 2And produce 5: 1 contrast.
According to embodiment 17, liquid crystal indicator can be accomplished colourless in the printing opacity spectrum of chief ray incident direction and light reflection direction.Thereby obtain having the colourless demonstration of high brightness, the result can obtain having the reflective LCD device of good visual degree.
In contrast, consider in the liquid crystal indicator of embodiment 17, to establish again the eigenwert n of phase plate now 3It is 1.0 situation.
Be respectively 0.065 and 0.010 in the chief ray incident direction (position angle is 90 °, and the elevation angle is 30 ° to 60 °) and the colourless degree W of light reflection direction.
Be placed on when using on office's table when liquid crystal indicator similarly is contained in subnotebook PC and computer, light is shown as brown, and the surface brightness during bright the demonstration is 40cd/m 2, contrast is 3: 1.
When further observation details,, be coloured at the transmitted spectrum of chief ray reflection direction though be colourless at the transmitted spectrum of chief ray incident direction.As everyone knows, light shows thereby is brown.
To above similar mode in, in the liquid crystal indicator of embodiment 21 in contrast, also the optical path difference with phase plate is decided to be 120nm.Colourless degree W at the transmitted spectrum of chief ray incident direction (position angle be 90 ° and the elevation angle is 30 ° to 60 °) and light reflection direction (elevation angle is 0 °) is respectively 0.035 and 0.041.
The result, when liquid crystal indicator similarly is contained on the subnotebook PC, the table that computer is placed on office is gone up and when observing Show Color, because be the band look the transmitted spectrum both of chief ray incident direction and light reflection direction in the case, so light is shown as purple.The surface brightness that light shows is 20cd/m 2, and the contrast that obtains only is 2: 1.
Much less,, can not become colourlessly at the transmitted spectrum of chief ray incident direction and light reflection direction, then can not obtain to have the colourless demonstration of high brightness if in reflective LCD device.
Embodiment 18
In embodiment 18, employed beam reflector is the same with beam reflector among the embodiment 21, and the angle between the plane of a plurality of reflecting surface and liquid crystal display is made as 0 °, 10 ° and 20 ° of three values.Other the structure substantially with embodiment 17 in identical.
In embodiment 22, the position angle of main incident light direction is 90 °, and the elevation angle is 20 ° to 60 °.The elevation angle of light reflection direction is 0 °, and the colourless degree W of transmitted spectrum is respectively 0.010 and 0.010.
Reflective LCD device according to embodiment 18 is installed on the portable data assistance, and this terminal is with using outside.
When observing Show Color by various angles of change or the like, under any circumstance light shows it almost is colourless.
On the other hand, the surface brightness that light shows changes according to service condition basically, and equals 210 to 400cd/m 2, can in all case use.Obtain 5: 1 contrast.
Equally, colourless by making liquid crystal indicator in embodiment 18 at the transmitted spectrum of chief ray incident direction and light reflection direction, can obtain to have the colourless demonstration of high brightness.
Because in embodiment 18, it is promptly 0 °, 10 ° and 20 ° of three different angles that the angle of the reflecting surface of beam reflector is provided with, the light incident direction has been widened, thereby can adapt to service condition widely.
Embodiment 19
In embodiment 19, though similar among the beam reflector that uses and the embodiment 17, reflecting surface is not very level and smooth face, but promptly there is small reflecting surface in so a kind of reverberator on each reflecting surface, thereby forms a light scatter face.All the other structures are the same basically.
When making beam reflector, form the light scatter face by the mould that uses blasting treatment.
Equally, in embodiment 19, be respectively 0.015 and 0.010 in the colourless degree W of the transmitted spectrum of chief ray incident direction (orientation is 90 °, and the elevation angle is 20 ° to 70 °) and online reflection direction (elevation angle is 0 °).
When the reflective LCD device according to embodiment 19 was installed on the subnotebook PC, computer was placed on office's table, and liquid crystal indicator is oblique with 30 ° of angle lappings, and observed display device from the normal direction on liquid crystal indicator plane.
Can obtain almost colourless light certainly shows.Surface brightness when light shows is 60cd/m 2And contrast is 5: 1, thereby much less can obtain enough performances.
Embodiment 20
In embodiment 20, change the shape of cross section that constitutes the beam reflector of light scatter face among the embodiment 19, the angle between the normal on reflecting surface and liquid crystal display plane is made as 0 °, 10 ° and 20 ° three kinds.Other structure is the same basically.
Colourless degree W at the transmitted spectrum of chief ray incident direction (position angle is 90 °, and the elevation angle is 20 ° to 60 °) and light reflection direction (elevation angle is 0 °) is respectively 0.010 and 0.010.
When the reflective LCD device according to embodiment 20 is installed on the portable data assistance, this terminal is with using outside, and when observing Show Color or the like by changing various angles, in all case can obtain almost is that colourless light shows.
Although the surface brightness that light shows changes according to service condition basically, and equals 180 to 450cd/m 2, this brightness can both be used in any occasion, and contrast equals 5: 1 in the case.
Therefore, according to embodiment 20, can obtain to have the colourless demonstration of good visual degree and high brightness.
Because reflecting surface has three different angles and has the light scatter performance, thus widened the light incident direction, thus this liquid crystal indicator can adapt to service condition widely.
Embodiment 21
In embodiment 21, the eigenwert n of the phase plate 7 of the reflective LCD device in embodiment 21 3Be decided to be-0.01.Other structure is the same substantially.
In embodiment 21, be respectively 0.009 and 0.010 in the colourless degree W of the transmitted spectrum of chief ray incident direction (position angle is 90 °, and the elevation angle is 30 ° to 60 °) and light reflection direction (elevation angle is 0 °).
Subnotebook PC according to the reflective LCD device of present embodiment 21 is housed, is placed on office's table, and when the normal direction of liquid crystal display face is observed show state, obtain almost colourless bright demonstration with 30 ° of inclination angles.
Surface brightness during bright in this case the demonstration is 65cd/m 2, contrast is 5: 1.
Thereby much less, the chief ray incident direction by making liquid crystal indicator in embodiment 21 and the transmitted spectrum of light reflection direction are colourless, the colourless demonstration that can obtain to have high briliancy equally.
Embodiment 22
In Figure 31, when the optical path difference of phase plate is decided to be about 600nm, the expression wavelength be 550nm the transmitted light polarization state a bit, moved on to and (S shown in Figure 31 1, S 2) 1 B on the straight line that intersects of face.Transmitted light with other wavelength is converted to the polarization state that equals above-mentioned polarization state substantially.
Suppose that the absorption axes of going up polarizer is made as the Y in Figure 31 mid point B orientation 2
Under the situation of angle in 40 ° to 50 ° scopes between the direction of the absorption axes of following polarizer and following oriented layer orientation process, the position angle of putting B with the experimental technique acquisition be (370 °-θ-2a).
The position angle of the absorption axes of last polarizer is expressed from the next.
185°-θ/2+a ……(31)
In scope was 200 ° to 270 ° torsion angle scope, the position angle of last polarizer absorption axes was inevitable in-20 ° to 20 ° scopes.
Eigenwert n in the case 3With the relation of colourless degree W as shown in figure 38.Though the inclination difference of curve can find out that its trend is to shown in Figure 35 similar.
In other words, as eigenwert n 3Be timing, it is big that colourless degree W becomes, and transmitted spectrum is yellow (predominant wavelength is about 585nm).At eigenwert n 3Approximate greatly 0.3 or littler zone in, much less, colourless degree W is 0.02 or littler, and transmitted spectrum is colourless.
As mentioned above, the position angle of polarizer absorption axes under decision, the position angle of phase shift bobbin (slowaxis), and go up after the position angle of polarizer absorption axes, the estimation of the tone of the variation of the optical path difference of phase plate and the bright demonstration of liquid crystal display substrate face normal direction is as follows:
Colourless in this case degree W to the dependence of phase plate optical path difference as shown in 39.When optical path difference during in 540 to 680nm scopes, colourless degree W is 0.02 or littler, and almost is colourless along the transmitted spectrum of substrate face normal direction.
In such scope, contrast be 8: 1 or bigger and when light shows transmissivity be 25% or bigger, and under any circumstance can both obtain enough values.
As the △ nd (the △ n of state liquid crystal material in bulk and thickness of liquid crystal layer d are to be amassed) by changing liquid crystal layer when measuring colourless degree W, colourless degree W all is 0.02 or littler when any △ nd.
Equally, in above situation, become colourlessly at the transmitted spectrum of substrate face normal direction, and obtain high-transmission rate and high-contrast.
As embodiment 22, the orientation of the optical path difference of phase plate 7 and last polarizer 8 absorption axes changes to by the value within the top scope that experiment obtained among the embodiment 17, and the optical path difference under the 550nm wavelength situation of phase plate 7 is decided to be 600nm, and the position angle of last polarizer 8 absorption axes is changed to after 105 °, observes show state.
Be made as 90 ° at the position angle of chief ray incident direction, the elevation angle is made as 30 ° to 60 °, and is made as 0 ° at the elevation angle of light reflection direction.The colourless degree W of transmission spectrum is respectively 0.012 and 0.003, and bright demonstration almost is colourless.Surface brightness when light shows is 60cd/m 2, and contrast is 6: 1.
Equally,, can become colourlessly at the transmitted spectrum of chief ray incident direction and light reflection direction, and can obtain to have and be shown as the efficient reflective LCD device that colourless good visibility and high brightness show according to embodiment 22.
In contrast, as the eigenwert n of phase plate 7 again in embodiment 22 3Being changed to 1.0 o'clock, is respectively 0.100 and 0.010 in the colourless degree W of the transmitted spectrum of chief ray incident direction (position angle is 90 °, and the elevation angle is 30 ° to 60 °) and light reflection direction (elevation angle is 0 °).
Although the transmitted spectrum along the chief ray incident direction is colourless, be coloured at the transmitted spectrum of chief ray reflection direction.When observing Show Color, light is shown as brown.
Thereby, for 60cd/m 2Surface brightness, contrast only is 3: 1.Equally, in this case,, can not obtain to have the colourless demonstration of high brightness if find that along the transmitted spectrum of chief ray incident direction and light reflection direction be not colourless simultaneously.
In contrast, also the optical path difference of the phase plate of liquid crystal indicator among the embodiment 22 is made as 500nm.
In this case, be 0.044 in the colourless degree W of the transmitted spectrum of chief ray incident direction (position angle is 90 °, and the elevation angle is 30 ° to 60 °), and be 0.029 in the colourless degree W of the transmitted spectrum of light reflection direction (elevation angle is 0 °).
On with such liquid crystal indicator dress subnotebook PC, and this computer is placed on the table of office, when observing Show Color, because two transmitted spectrums at chief ray incident direction and light reflection direction all are coloured, so light is shown in green, and the surface brightness when light shows is 55cd/m 2, and only obtain 2: 1 contrast.
Also can understand from this situation,, just can not obtain to have the colourless demonstration of high brightness if be not all colourlessly at the transmitted spectrum of chief ray incident direction and light reflection direction.
According to the present invention because can become simultaneously at the transmitted spectrum of chief ray incident direction and light reflection direction colourless, so can easily obtain to have the reflective LCD device that is shown as colourless high visibility and high brightness.

Claims (16)

1. a reflective LCD device comprises a reverberator, and one is passed through superimposed upper and lower oriented layer, upper and lower electrode, upper and lower substrate, and be arranged in neatly that the liquid crystal layer above and below makes it respectively towards the other side's upper and lower polarizer and the liquid crystal cell that constitutes, wherein
Described liquid crystal cell has the visual angle correlativity, and for the light with institute's required angle incident, the transmissivity of dark viewing area to bright viewing area can become less than 2 at its desired position angle, and
Azimuthal direction of described requirement is alignd with the direction that main light source light incides described liquid crystal cell.
2. a reflective LCD device comprises a reverberator, and one is passed through superimposed upper and lower oriented layer, upper and lower electrode, upper and lower substrate, and be arranged in neatly that the liquid crystal layer above and below makes it respectively towards the other side's upper and lower polarizer and the liquid crystal cell that constitutes, wherein
Described liquid crystal cell has the visual angle correlativity, and for the light with institute's required angle incident, the transmissivity of dark viewing area to bright viewing area can become less than 2 at its desired position angle, and
Azimuthal direction of described requirement is registered to the direction of 90 ° of user side's parallactic angles on the display surface of described liquid crystal cell.
3. a reflective LCD device comprises a reverberator, and one is passed through superimposed upper and lower oriented layer, upper and lower electrode, upper and lower substrate, and be arranged in neatly that the liquid crystal layer above and below makes it respectively towards the other side's upper and lower polarizer and the liquid crystal cell that constitutes, wherein
Described liquid crystal cell has the visual angle correlativity, and for the line with institute's required angle incident, the transmissivity of dark viewing area to bright viewing area can become less than 2 at its desired position angle, and
Azimuthal direction of described requirement is aimed at the horizontal direction of reflective LCD device.
4. reflective LCD device according to claim 2 or 3, wherein
Described reverberator is reflected into the main light source light that is mapped to described liquid crystal cell user's apparent direction of ± 10 °.
5. reflective LCD device according to claim 2 or 3, wherein
Described reverberator is reflected into the main light source light that is mapped to described liquid crystal display in the direction of 20 ° of user perspectives.
6. reflective LCD device according to claim 2 or 3, wherein
Between described polarizer down and described reverberator, provide a light scatter layer.
7. a reflective LCD device comprises a superimposed according to the order of sequence polarizer, goes up substrate for one, and a top electrode is gone up oriented layer for one, a liquid crystal layer, and a following oriented layer, a bottom electrode, and the liquid crystal cell that subtegulum forms, wherein
Described reverberator is to form between described bottom electrode and described subtegulum, makes it to be reflected into the main light source light that is mapped to described liquid crystal cell ± 10 ° of user's apparent directions, and
One is formed at the described color filter of going up between substrate and the described reverberator.
8. a reflective LCD device comprises a superimposed in order inclined to one side device, goes up substrate for one, and a top electrode is gone up oriented layer for one, a liquid crystal layer, and a following oriented layer, a bottom electrode, and the liquid crystal cell that subtegulum forms, wherein
Described reverberator is to form between described bottom electrode and described subtegulum, thereby it can be reflected into the main light source light that is mapped to described liquid crystal cell in 20 ° user perspective direction, and
One is formed at the described color filter of going up between substrate and the described reverberator.
9. reflective LCD device according to claim 7 or 8, wherein
Described liquid crystal cell has the visual angle correlativity, obtains to approach most 1 contrast at desired position angle for the light with the light of desired angle incident, and
An azimuthal direction is registered to the direction of 90 ° of user side's parallactic angles on the display surface of described liquid crystal cell.
10. reflective LCD device according to claim 2,3 or 9, wherein
Inclination angle, surface, described reflection horizon is within 10 ° and 35 °.
11. a reflective LCD device comprises a superimposed in order polarizer, goes up substrate for one, a top electrode is gone up oriented layer for one, a liquid crystal layer, and a following oriented layer, a bottom electrode, and the liquid crystal cell that subtegulum forms, wherein
The split axle of described liquid crystal layer when a voltage is applied to described liquid crystal layer, is registered to the direction perpendicular to the main light source that incides described liquid crystal cell.
12. a reflective LCD device comprises:
Two transparent substrates are configured in surface one side and back one side of liquid crystal layer, clamp a liquid crystal layer mutually face-to-face;
A phase plate is arranged on the outside surface of the described transparent substrate of a surperficial side;
The polarizer of a face side is arranged on the outside surface of described phase plate;
The polarizer of a back side is arranged in the outside of the described transparent substrate of a next side; And
A beam reflector is arranged in the outside of the polarizer of described back one side, wherein
When described phase plate is made as n in the refractive index of two electronoptical main axis directions (quadrature in the plane at described phase plate) XAnd n Y(n X＞n Y), and be set to n along the refractive index of described phase plate thickness direction zThe time, determine that the refraction of described phase plate is counted eigenwert to satisfy following formula:
0.3≥(n z-n x)/(n y-n x)
13. the reflective LCD device according to claim 12, wherein
When within the scope of optical path difference at 320nm to 420nm of described phase plate, and
Divide the direction of orientation process direction of two oriented layers of the forward surface that is arranged in described transparent substrate equally, be decided to be 0 ° of orientation, and when transparent substrate visual observation on described, counterclockwise define the position angle,
The position angle of described polarizer absorption axes down is within 140 ° to 185 ° scope;
The position angle of described phase plate slow axis (S10Waxis) is within 45 ° to 80 ° scope; And
The described position angle of polarizer absorption axes of going up is within-10 ° to 35 ° scope.
14. the reflective LCD device according to claim 12,
When within the scope of optical path difference at 540nm to 680nm of described phase plate, and
The direction of orientation process direction of dividing two oriented layers of the forward surface that is arranged in described transparent substrate equally is decided to be 0 ° of orientation, and when transparent substrate visual observation on described, counterclockwise defines the position angle.
The position angle of described polarizer absorption axes down is within 140 ° to 185 ° scope;
The position angle of described phase plate slow axis (slowaxis) is within 45 ° to 80 ° scope; And
The described position angle of polarizer absorption axes of going up is within 90 ° to 35 ° scope.
15. the reflective LCD device according to claim 12, wherein said beam reflector has the reflecting surface of two or more different angles.
16. the reflective LCD device according to claim 12,
Described beam reflector is to construct by the reflecting surface with light scattering property.
CNB961005491A 1995-04-04 1996-04-04 Reflective liquid crystal display device Expired - Lifetime CN1140834C (en)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
JP78601/1995 1995-04-04
JP78601/95 1995-04-04
JP07078601A JP3075134B2 (en) 1995-04-04 1995-04-04 Reflective liquid crystal display
JP286006/95 1995-11-02
JP286006/1995 1995-11-02
JP7286006A JPH09127503A (en) 1995-11-02 1995-11-02 Reflection type liquid crystal display device

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CN1140834C CN1140834C (en) 2004-03-03

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Publication number Priority date Publication date Assignee Title
CN106025452A (en) * 2016-06-08 2016-10-12 合肥工业大学 Phase shift unit and terahertz reflection-type liquid crystal phase shifter formed by phase shift unit

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JP4139393B2 (en) * 2005-02-01 2008-08-27 シャープ株式会社 Reflective display device

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JP3259303B2 (en) * 1992-01-28 2002-02-25 セイコーエプソン株式会社 Liquid crystal display
JP3018603B2 (en) * 1991-07-12 2000-03-13 セイコーエプソン株式会社 Reflective liquid crystal display
JP2796212B2 (en) * 1992-04-10 1998-09-10 シャープ株式会社 Liquid crystal display
JPH06337414A (en) * 1993-05-28 1994-12-06 Toshiba Corp Reflection type liquid crystal display element
JPH0713153A (en) * 1993-06-29 1995-01-17 Kyocera Corp Reflection type liquid crystal display device

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106025452A (en) * 2016-06-08 2016-10-12 合肥工业大学 Phase shift unit and terahertz reflection-type liquid crystal phase shifter formed by phase shift unit

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