TW512250B - Light control devices and configuration for reflective type liquid crystal displays and display having the same - Google Patents

Abstract

Light control devices and configuration for reflective type liquid crystal displays and display having the same. The objective of the invention to improve the display quality of a reflection type liquid crystal display (LCDs) device with micro-optical devices and novel configuration. The microstructure surface profile, such as microlens or microprism is placed on the front surface of top substrate of reflective LCDs. These microstructure surface profiles can be fabricated on the top substrate of reflective LCDs cell directly, or fabricated on plastic film, or plastic sheet that is then pasted on the surface of a top substrate. By properly designing the refraction or diffraction functions of these micro-optical devices, the reflected light of reflective LCDs can be converted into the desired viewing region of common viewers, yielding much improved image quality. The above mentioned reflective LCDs cover all types of LC models. The basic structure of a reflective LCDs cell is an LC layer sandwiched between transparent top substrate and reflective bottom substrate.

Description

512250 V. Description of the invention (1) Creative background 1. Creative field: This creative is aimed at improving the image quality of reflective liquid crystal displays that can modulate and reflect external incident light to form an image. It also explains the design and manufacturing method of this component. 2. Introduction of related technologies · In recent years, with the popularization of the Internet and wireless communication, the era of high-speed information circulation has begun; personalized communication and information display media have become a foreseeable demand trend, such as a new generation combining the Internet Road's cellular phones, personal digital assistants, hand held computers, and so-called electronic newspapers (e 1 ectr ο nicpaper) are all predictable new products. This kind of product is not enough to display the tribute, and requires a South resolution, high-chroma imaging element as a data display and exchange element. Among them, the reflective liquid crystal display does not use a built-in light source, but reflects the incoming ambient light to illuminate the image. This has the advantages of reducing the thickness and weight of the display and saving power > consumption. At the same time, because reflective LCDs can produce images without the need for a built-in light source, and when the outdoor ambient light is strong, the more vivid the images they produce, the better the contrast, unlike the general built-in light source. The transmissive liquid crystal display has the disadvantage that the image contrast decreases with the increase of the ambient light intensity. Therefore, reflective liquid crystal displays are extremely power-saving and suitable for general outdoor or strong ambient light.

Page 6 512250 V. Description of the invention (2) Display used in the environment. Traditionally, twisted nematic (TN) and super twisted nematic (STN) liquid crystals commonly used in general transmissive liquid crystal displays are used in the second polarizer (p ο 1 arizer). A reflective surface is added to complete a reflective liquid crystal display. However, due to the use of two polarizing plates, the amount of light passing through is greatly reduced, and the brightness is seriously insufficient. In order to solve this problem, some liquid crystal development mechanisms that do not require polarizers are used in reflective liquid crystal displays, such as light-scattering polymer-dispersed liquid crystals (PDLC), or light-absorptive host-guest liquid crystals (PCGH). ), The light that is not absorbed or scattered by the liquid crystal layer is reflected to form a bright image, and the amount of absorption or scattering determines the gray level of the image. Although the brightness of this type of display mechanism has been greatly improved, the dark state is not sufficiently dark, so the image contrast and the number of gray levels are slightly insufficient. In order to obtain the best image quality, the liquid crystal display structure of a single polarizer is a better choice, which includes polarized rotation (ρ ο 1 arizati ο nr 〇ta) such as RTN, RSTN, MTN, ECB, and ROCB. ΐ i ο η) and birefringence effect (monoreflective liquid crystal display) as an example, when the incident light passes through the polarizer as shown in Figure 1, the light becomes linearly polarized light and passes through the liquid crystal layer. After being reflected by the bottom reflection plate in the liquid crystal display, the reflected light passes through the liquid crystal layer again. After passing through the liquid crystal layer twice, the liquid crystal is modulated. The polarization state of the light (ρ ο 1 arizati ο η) is also changed, and finally After the original polarizer on the surface is detected, a change in light intensity is generated, and then images with different gray levels are generated. If a light path difference is added in front of the display is four

512250 5. Description of the invention (3) The wave plate with a half wavelength can make the entire liquid crystal cell form an equivalent optical effect of cross polarizers, generate a sufficiently dark state, and improve the contrast. At the same time, due to the equivalent liquid crystal layer symmetry effect, the phase self-compensation effect is produced, so it has the advantage of wide viewing angle. Since a reflective liquid crystal display reflects an incident ambient light to generate an image, the image quality observed by an observer is determined by the distribution of the reflected light. According to the principle of optical reflection, when light enters a specular reflecting surface, the reflected light and incident light will be at the same angle between the two ends of the normal of the reflection plane, which are called the incident angle and the reflection angle, respectively, as shown in Figure 2. This is called specular reflection. Therefore, when the ambient light enters the reflective liquid crystal display obliquely, the reflected light is also distributed in the corresponding oblique reflection angle distribution area. However, for the normal observing angle that the observer is often in, enough light is often not observed, so that the reflective LCD cannot display sufficient brightness and contrast in the forward direction, as shown in Figure 3. . If the observer rotates the display in order to observe a brighter image formed by the majority of the reflected light, the surface reflected light (g 1 are) generated by the surface reflection of the display will overlap with the modulated image reflected light, resulting in an image The contrast is reduced. Even images of light sources such as the sun, or indoor table lamps, roof lamps, etc. are observed in this direction. Therefore, in order to improve the problems described above, it is effective to control the distribution of the reflected light after modulation so that it is distributed in the forward direction of the observer, and at the same time eliminate the surface reflected light generated by the display surface and reflection. Improve the brightness and contrast of the display image of the reflective LCD. In this work, "Light distribution control elements for reflective liquid crystal displays",

512250 V. Description of the invention (4): The micro-optical element structure can be deflected in and out of the liquid;; J reflected liquid crystal display after the modulation of the reflected light: c diameter, the distribution in the wrong direction, so that observation 2 can also be distributed The quality of the image of the monitor is close to the forward direction to a display with sufficient brightness and contrast, and the effective viewing angle makes the reflective liquid crystal display: crying; the second-type liquid crystal display potential is more extensive. The use of the dry wall and the market Creative overview The purpose of the work is to improve the reflective liquid crystal display (the modalities of the liquid crystal display) W image quality. All the reflections are added on the upper surface of the display—and j is the surface change of the reflective liquid microlens array (MiCro-lens /, A ^ ,,,, α), such as

Micro-prism Array). 'Yr: ay', or micro-array display, can be made directly on the surface of the display. / The garment is made in the form of a light-transmissive film layer. When incident light passes through this element = the reflective surface of the liquid crystal display = apparatus, the light is deflected, passes through the inflection element, and is deflected once again. When ^ _ is passed again, the obliquely incident flower L can be designed as the deflection selection page of this element is not 'two passes through this wind'-entering the display and reflecting out at the incident. This can be ", during the sacrifice, the light distribution has a large disadvantage such as insufficient increase ratio. When viewing in the same direction, the brightness of the image is too high. Due to the microstructure on the surface, two 70 pieces are provided to the viewing angle.疋 (σ 〇ί χ deflected to the near normal, when the sacrifice to the sacrifice, 氺 八 1 ^ # gain). In this way, you can avoid the need to increase the size of the knife cloth and increase the 512250.

V. Description of the invention (5) The specular reflection of (5) will be partially ^ ^ --- 丨 The scattering surface replaced by the scattering or reflection of the knife will be seen by the strong reflection shadow of the ambient light source. The observer will not show it. And> reduce the contrast of the image, and reduce the light deflection control of such micro-optical elements to achieve the production methods such as micro-etching, micro-etching, ion implantation, or thermal ion laser cutting. This can be achieved by making diffraction—the creation is described in detail as optical elements that can be designed in different ways. The method of production can be changed using semiconductors, holography, mechanical or optical, in terms of optics, refraction or deflection. Effect of optical methods. Specifically, an off-axis (structural element, a transparent plastic sheet shown in reverse as shown in FIG. 4) is specifically described. When light will be incident on a microlens array, this one will be regarded as a near axis) The structure can be seen as transparent plastic microlenses. 'When the oblique lens focuses on the element to reflect the condensed light through the optical axis of the reflective lens, when these reflected light passes through the direct-formed film layer designed by this shooting liquid, it is parallel to the focal point. After the liquid crystal display, the adjacent transmissive display of the focal point is incomplete, and the incident light on the axis of the mirror is attached to the display mode. If a mirror is emitted next to the display, the is surface circular lens indicator is attached to the surface to cut off the incident display. Calculate the reflection of the other half of the point light source will be biased into a slightly transparent surface or surface. For some mirrors, when the focal length of the mirror is between the lens and the light, it is folded into a non-mirror array to make a half of the body as shown in Figure 5. The incident distance is exactly equal to. Therefore, the approach method

Page 10 512250 V. Description of the invention (6) The forward direction of the line exits in parallel. In this way, the effect of changing the reflected light distribution area to the forward area can be achieved. Of course, for the reflected light incident through each micro-lens, the distribution of the reflected light will not be limited to penetrating a single lens, and may be reflected to the area of more than two lenses, resulting in specific two different exit angles. As shown in Figure 6. However, relative to the original mirror reflection angle, these angles are smaller than the original mirror reflection angle, and they also have the effect of compressing the reflected light distribution angle.

In order to further compress the distribution angle of light and change the phenomenon of the specific distribution angle as described above, we shorten the focal length of the lens so that the focal point is between the microlens array and the internal reflection surface, as shown in Figure 7. The exit angles will have a wider distribution without being limited to a certain number of exit angles, and a better light compression effect will be obtained. Figure 8 shows a microlens light control element with a lens radius of 100um, a focal length of 466.67um, and a lens f / # = 2.33, obtained from a reflective liquid crystal display with a distance of 1 30 Oura from the upper glass surface to the metal reflective surface. One-dimensional light compression effect. When light is incident obliquely to the left at 300, the distribution of reflected light. The distribution of the reflected light is compressed to near the center normal direction, while the light distribution is from 0 ° to 20 °, about 20 °

Expand. Compared with the reflectivity of MgO standard whiteboard, the reflected light has a high gain in the effective distribution range close to the forward viewing angle. Therefore, it is possible to effectively improve the image brightness and contrast of the reflective liquid crystal display in the viewing angle. In addition, due to the focusing effect of the lens, as shown in Fig. 9, when incident light is incident at (30 °, 27 0.), a light distribution control effect in two dimensions of X and y can be obtained, so that the reflection of the liquid crystal display The efficiency is further enhanced. In addition, in order to control the

Page 11 512250 V. Description of the invention (7) In the situation, the relative position X, y of the incomplete circular lens microlens array between the lenses can be designed in different sizes, proportions, and dislocations. An example is shown in Figure 10. In addition to the changes in the relative positions of the microlenses relative to each other, the different turning distributions of the microlenses between each other (detailed description) can also have the effect of controlling the distribution of the reflected light, so that a greater control effect can be achieved. The off-axis lens of this asymmetric non-complete circular lens is designed as an off-axis non-complete circular lens with a part of the lens body cut off. The focal length f of the lens is in the range of: 0 <ί <2 X (the distance from the lens to the reflective surface of the reflective liquid crystal display / the average refractive index of the liquid crystal cell). The smaller the f-number of the lens is, the better, there will be a better effect of controlling the light distribution at f-n u m be r &lt; 4. This off-axis microlens can be made using various micro-optical element manufacturing methods such as photoresist heat-resistance (ph〇〇〇resist re-flow), gray b mask (gray scale mask), thunder Various methods such as laser tooling, index gradation, or Ce-beam diFect write are used to make refractive microlenses. In addition, Fresnel can also be used. , S zone plate) theory to Si as an absorption or phase Fresnel ring diffraction lens (Fresnel microlens). Specific description 2 In addition to the structure of the off-axis lens, the chirped structure is also an element that can change the light refraction path. As shown in Figure 11, when the light is inclined obliquely from a right angle

Page 12 512250 V. Description of the invention The final reflection of the right-angled surface / control of the cloth, etc. 稜鏡 / solid angle, while the angle of the bottom corner of the right-angle side, the emissivity of the angle will affect the light deflection angle due to the general oblique angle The direction of incidence should be toward the angle of the observer, slightly dihedral, and this one is smaller and larger. The light control effect will be reflected by the oblique rays and the angle will be out of the corner. The display is aimed at the light entering the direction of small and refraction (8). The light will have the effect. Structure, right-angled edges are two degrees in size, and the effect of light can be set. The display is therefore facing down. Needle shot, the reflection is close to this edge, where the end mirror contacts a light source smaller than, and the angle of deflection of the edge is small. So the better the angle of the two bottom corners should be. The light will be reflected from the face to the direction mirror, which means the display 90. Cube mirrors and liquidity, because the bottom angle is mostly around the knot, the inverse medium-small range surface can be refracted through 稜鏡 ° to reach the two small one incident light values on the base surface of a structure, Above the observation angle, the side surface corresponding to the angle of the three-structure reflection light angle-controlled reflection light distribution-control transmission type liquid crystal display is: 0 &lt; 0 &lt; 45. &lt; The deflection is close to positive and re-reflects again to improve the light division. The two bottom angles on the surface of the plate are different. This 稜鏡 螭 base version of the specific source of the fold to get the desired slope of the controller of about ten degrees to close to the forward direction where the light source is located toward the light source side &gt;

Search data 1. Kayoko Ueda, Masaru Honda, and Yuk i o Yasunor i, n Light control sheet and liquid crystal display device comprising the same, M U. S. Patent 5, 767, 9 3 5 (1 9 9 8) ·

Page 13 512250 V. Description of Invention (9) 2. Y. Itoh, S. FuJiwara, N. Kimura, S. Mizushiraa, F. F unada, and M. HijiKigawa, n Influence of rough Surface on the Optical Characteristics of Reflective LCD with a Polarizer &quot;, SIDJ 98 Digest, 221, 1998. 3. M. Wenyon, W. Molenti, and P. Ralli, &quot; White

Holographic Reflector for LCDs &quot;, SID '97 Digest, 691, 1997. 4. T. Uchida, T. Nakayama, T. Miyashita, and T. Ishinabe, &quot; A Novel Reflective LCD for High Resolution Color Displayn, ASID' 95 Digest , 599, I 9 9 5. 5. GT Va11i ath, ZA Coleman, J. L. Schindler, R. Polak, RB Akins, and KW Je 1 1ey, &quot; Design of Hologram for Brightness Enhancement in Color LCDs ", SID , 98 Digest, 1139, 1 9 9 8 · 6. H. Sek i, N. Sugiura, M. Shimizu, and T. Uchida, II A New Reflective guest-Host Display Using a Light-Scattering Filmn, SID '96 Digest 614, 1996. 7. Fu-Jen Ko, and Han-Ping David Shieh, n Improving the Quality of Liquid-Crystal Projection Image by Multilevel Diffractive Grating Technique ", JJ AP. Accepted for publication, March 15, 1999. 8. H. Hamada, F. Funada, M. Hi jikigawa, K. Awane,

Page 14 512250 V. Description of Invention (ίο) n Brightness Enhancement of an LCD Projector by a Planar Microlens Array11 3 SID 92 DIGEST, P.269 (1 9 9 2).

Page 15 512250 Schematic description of the first picture: The basic structure of a reflective liquid crystal display using a single polarizer; 冓. 1. Polarizer. 2. On the base version. 3. Color filters. 4. The metal reflective electrode forms the reflective surface of light. 5. Liquid crystal layer. 6. Incident light.

7. Reflected light. 8. The polarization direction of the incident light. 9. The polarization direction of the incident light after passing through the polarizer. 1 0. The polarization direction of the reflected light after being modulated by the liquid crystal layer. 11. The polarization direction of the reflected light after it has been subjected to polarization analysis. 1 2. The base version. '1 3. Reflective LCD.

The second picture: the specular reflection on the flat metal reflective surface of the reflective liquid crystal display and the glass surface on the display. 14. Flat reflective surface (metal electrode or upper glass surface). , 1 5. The normal of the vertical reflecting surface. 16. Incident angle: the angle between the incident light and the normal. 1 7. Exit angle: the angle between the exit ray and the normal.

Page 16 512250 Brief description of the third diagram: The direction of the light source and the viewer's position under the general operating environment of the reflective liquid crystal display shown in Fig. (1), and the picture produced on the metal electrode and the glass surface of the display (II) ) As shown in the specular reflection phenomenon. 1 8. Ambient light source. 1 9. Reflected light reflected by a metal electrode of a reflective liquid crystal display. 2 0. Reflected light generated by the upper glass surface of a reflective liquid crystal display. 21. The observation position where the viewer is located. Figure 4: A side view of a microlens array with a non-complete circular lens applied to a reflective liquid crystal display, and a schematic diagram of the reflection angle control of reflected light. 2 2. Non-complete circular lens microlens array with off-axis design. 2 3. Outgoing reflected light refracted by the microlens array of a non-complete circular lens. Fifth image: a side view and a top view of a microlens of a single non-complete circular lens. 2 4. Mirror lens axis. 25. Cut-off lens body part 2 6. Retained off-axis microlens structure Figure 6: Multiple exit angle distributions of reflected light passing through different microlenses in the microlens array. 2 2. A, 2 2. B. Different lenses a, b in an off-axis microlens array. 2 3. A, 2 3. B. The reflected light that penetrates the lenses a and b, respectively. 2 7. A, 2 7. B. Correspond to the exit angles of the reflected light 2 3. A, 2 3. B refracted by the lenses a, b, respectively.

512250 Schematic description 2 7. Focus of incident light 6 after condensing by micro lens. Figure 7 · Microlens array. The focus of the column is on the deflection and distribution of the reflected light between the lens array and the reflecting surface. 6.a, 6. b, 6. c. Incident light incident on different positions of the mirror surface of the microlens. 28.a, 29.b, 29.C. correspond to the reflected light from the incident light 6.a, 6.b, 6.c. Figure 8: A microlens light control element with a lens radius of 100um, a focal length of 466.67um, and a lens f / # = 2. 3 3 is applied to a reflective liquid crystal with a distance of 1 3 0 0 um from the upper glass surface to the metal reflective surface The one-dimensional light compression effect obtained by the display. 2 9. The relationship between the reflectance and the angle of M g 0 standard white plate. 3 0. Reflected light distribution curve after adding microlens array light controller. Ninth figure: The polar coordinates of the reflected light distribution under the two-dimensional array of the microlenses of the incomplete circular lens as shown in (8). Figure 10: Various two-dimensional distributions of microlens arrays with incomplete circular lenses, including changes in position distribution and rotation. 3 2. Microlens array distribution with changing position and rotation distribution. Figure 11: Side view of the application of a micro-array light controller to a reflective liquid crystal display.

512250

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Claims (1)

512250 VI. Application for patent scope 1 · A surface change of the light control sheet of the light distribution of the light control element; it can change the reflective liquid crystal display and or the light control film or have such light ^ = this light The control sheet, or light control film, or a light control function change is an asymmetric off-axis design penetrating microlens array. "&Quot; This microlens array is an off-axis lens with a non-complete circular lens, = The bucket cuts off the incomplete circular lens of a part of the body. The Z-axis sigh meter is 2 · — a type of reflective liquid crystal display device, including: a substrate, a base plate, a liquid crystal layer, a reflective surface, and a light control sheet such as the scope of the patent application, or a light control film, or has light The surface of the control function changes. Different liquid crystal layer designs can include one upper polarizing plate, or two upper and lower polarizing plates. 3. The reflective liquid crystal display device according to item 2 of the scope of patent application, wherein the light control sheet or light control film is placed on the outer surface of the upper substrate of the reflective liquid crystal display. The reflected light reflected by the display will pass through this element to form a deflection in the direction. In reflective liquid crystal display applications that require a polarizing plate, it can be placed below or above the polarizing plate. 4 · If the reflection type liquid crystal display device in the second item of the patent application, the surface change with the light control function is a structure of making tiny optical elements directly on the upper version of the reflection type liquid crystal display, the light incident and reflected The reflected light reflected by the liquid crystal display will pass through this element, forming a deflection in the direction. 5 · If the light control element of the scope of patent application No. 1, its micro lens array system Sixth, the scope of patent application __. It can change the distribution of the relative position between the lenses, and the effect. The first control angle and 6. If the light control element of the scope of the patent application can change the distribution of the asymmetric off-axis lens along the lens axis, u lens array system distribution changes, to some specific different angles The relative angle of the vocal angle adjusts the angular distribution of the reflected light. &amp; 9 The incident light is modulated. 7. If the light control element of the patent application item 丨 can use a variety of micro-optical manufacturing methods to produce the lens array system (Fresnel) ring band theory to design the second garment element 'Xiru Using Fresnel as a method, semiconductor lithography / Xibu step microlenses can be used to create patterns and depth changes. 2 or 准 using an excimer laser step mask to produce refractive surface products. ：:: Photoresist hot melt or gray tint to change the light condensing effect of the two-lens refraction lens by ion exchange or other methods, or the binary Philippine micro lens has a better range = lens condensing. Among them, the light controllability and accuracy as described in item 7 of the scope of patent application. The manufacturing method is to make a mother; then: Tian's micro lens array is made of a transparent plastic sheet or plastic T, and the film is controlled by means of a flip or stamp, and then the light control sheet ^ Light such as = into the so-called light control sheet or light plate surface. / Industrial film is attached to the upper base of the display. Xiang Zhiguang's production method can be directly produced on the surface of the base plate of the micro lens array of the display element. , /, For the upper version, such as glass or plastic. De Ben ^: light &amp; manufacturing elements' It is a kind of changeable weaving 捋 ... a light control sheet like light, a reflective LCD monitor shadow ^ Ί film, or surface change with such light control I page 21 6. Application for patent scope function; This light control film, or light and amine, B changes temptation for wearing temptation, 工 工 ,, Or, the surface with light control function is a tooth penetrating micro-macro array; the micro-macro structure or-prisms with unequal base angles are in contact with the two corners of the surface of the base plate, and " It is two smaller angles of less than 90 °. One of the right-angled sides is a right-angled edge. 11. A reflective liquid crystal display device comprising: a protective plate; a crystal layer; a reflective surface; Xianghua U film, or a liquid crystal layer design with a surface change of 5 冋 with light control function, can further include a polarizing plate on the upper and lower plates. Dimensions 3 ^ Reflective liquid crystal such as item u in the scope of patent application Display device, which shows: i: 4 pieces, or light control film, its placement position is reverse LCD display; "" two f appearance δ, light incident and reflected liquid crystal display ^, light will pass through this element, forming a deflection of the direction; reflective liquid crystal displays that require a polarized version of the polarized version Down or above. 1 on the top 13. The reflective liquid crystal display device such as the 11th in the scope of patent application, in which 2 &amp; ν, the surface change of the light control function is directly based on the reflective liquid crystal display. The structure of the small optical element is made, and the incident light and the reflected light reflected by the reflective liquid crystal display will pass through this element, and the deflection will be deflected. Shen Yu patented the siege of the 11th reflective LCD device, of which Page 22 512250 VI. The scope of the patent application is a chirped array. According to the direction of the applied source, the micro angle = the type of liquid source, and the first light source direction, and the angle of this smaller angle 15. If the scope of the 10th item in the scope of patent application is: 0 <not &lt; 45 series can use a variety of micro-optical components, the micro lens array lens, the manufacturing method can be :: = = binary Dona molecular laser engraving method to produce the pattern / shirt etching or 疋 quasi-thermolysis or gray scale mask, etc., the degree changes; can also use photoresistive fruit, or ion exchange, etc ... Light: Light-bending effect. Jinshe 211 forms a bias similar to 稜鏡. 6 · As in the manufacturing method of patent application No. 丨 5, τ is made into a mother film. Then: Tian Fan's micro lens array is made in The light-transmitting plastic sheet or plastic film is turned over by means of flip-molding or compression molding, and then this light control sheet or light so-called light control sheet or light-control surface is attached. The industrial amine is attached to the upper base of the display. The production method of the 1-foot version of the table can be directly produced in accordance with the method of item 5 in the scope of patent application. Two 'pieces, whose microlens array is on the surface of the rubber base plate. The upper base plate of w, such as glass or plastic 18. If the patent application scope item 1 or the microlens array is above, you can add -u Light control element, which further changes the distribution angle of the reflected light. The monthly, inch-shaped diffuser can be U. Such as the scope of patent application for item 1 or g1 () micro lens array, can be added if if °; = Light control element, which further changes the distribution angle of the reflected light.