JPH08507880A - Self-referenced halftone LCD - Google Patents

Abstract

(57) [Summary] A self-referenced halftone, grayscale liquid crystal display device having pixels subdivided into partial pixels (A ₁ ... A _N ). Each partial pixel has transparent electrodes (31 to 39) with a liquid crystal material interposed therebetween. The electrode of each partial pixel and the liquid crystal dielectric form a partial pixel capacitor that also functions as a control capacitor for the control capacitor. Each of the partial bipolar electrodes at one end of the dielectric overlaps another partial pixel, while the electrode at the other end overlaps another partial pixel. The structure is such that the partial pixel capacitors are electrically connected in series. Subpixels have electrodes of different areas, and therefore the subpixel capacitors of the pixels have different values. Applying a voltage to all of the sub-pixels connected in series with the pixel will result in no, one, or more than one sub-pixel of the pixel being activated depending on the magnitude of the voltage. As the applied voltage rises from zero, the subpixels with the lower capacitance will turn on first, since there will be a larger voltage drop across the lower valued capacitor. Thus, each pixel of the display has a gray scale capability that is a function of applied voltage.

Description

Detailed Description of the Invention                   Self-referenced halftone LCD                               Background of the Invention   The present invention relates to a liquid crystal display (LCD), and more particularly to an LC having halftone pixels. Regarding D.   Related art discloses an LCD having halftone pixels. Such ha Futone pixels are composed of sub-pixels with separate control capacitors. each Each sub-pixel has a series control capacitor and these sub-pixels are connected in parallel. Continued. Since each control capacitor is introduced in the structure of the liquid crystal panel, its structure is Somewhat complicated, which can be difficult to manufacture.   The name “Apparatus and Methad for for Bernat et al., Issued June 20, 1989.  Providing a Gray Scale Capability ina Liguid Crystal Disp1ay Unit '' rice National Patent No. 4,840,460 is incorporated herein by reference. Also , Apparatus and Methad for by K. Sarma, published April 20, 1993. U.S. Patent for `` Providing a Gray Scale in Liguid Crystal Flat Panel Displays '' No. 5,204,659 is also incorporated herein by reference.                               Summary of the invention   The present invention captures halftone pixels that do not require the introduction of a separate control capacitor. I am putting it in. Partial pixel of halftone pixel itself constitutes the control capacitor . The partial pixels are arranged in a meandering manner and electrically connected in series to form one partial pixel. The plate of pixels extends over and joins the plate of the next subpixel. It The sub-pixels are physically and electrically arranged in series, and a specific pixel of each sub-pixel is arranged. By setting the area, specific thickness, and specific dielectric constant, each partial pixel can be specified Subpixel transmittance, and therefore the turn-on sequence as a function of voltage. You can One advantage or feature of the present invention is that it requires fewer material layers and The soft tone display is less complicated.                           Brief description of the drawings   FIG. 1 is a schematic diagram of the capacitance associated with a subpixel of a pixel.   FIG. 2 shows a structure incorporating a self-referenced halftone partial pixel.   3a to 3h show some partial pixel configurations.   4a to 4b are schematic diagrams of partial pixel films relating to some combinations.   Figures 5a-5f show series and parallel combinations in corresponding electrical and structural schematics. The partial pixel configuration is shown.                       Description of the preferred embodiment   The capacitors 1, 2, 3, n and N in FIG. 1 are partial pixels 1 and 2 in one pixel. , 3, n to the capacitance C associated with each sub-pixel N_LC1, C_LC2, C_{LC 3} , C_LCn・ ・ ・ ・ ・ ・ C_LCNRepresents Pixel 10 is a well known low cost standard twist nematic Glass sandwiched between the glass sheets 20 and 22 is a glass sandwich. It is Ji. For example, ferroelectricity, polymer dispersion, smectic, super twist, electric Other liquid crystal materials or structures such as controlled birefringence may be used. Transparent, Electrically conductive indium tin oxide (ITO) film layers 31, 32, 33, 3 The glass sheet 20 can be covered by 4 and 35. Glass sheet 2 2 is covered by transparent and conductive ITO film layers 36, 37, 38 and 39 It Area A of each partial pixel 1, 2, 3, n and N₁, A₂, A₃, A_nAnd A_N Are membranes 31 and 36, 31 and 37, 32 and 37, 32 and 38 and 35 And 39 overlap. The overlapping ITO films 31 to 39 are dielectric Each partial pixel, which is an effective capacitor having the liquid crystal material 28 as a body, is electrically charged. Form a pole, or plate. Area A₁, A₂, A₃, A_nAnd A_NIs different Therefore, the capacitance related to each of the partial pixels 1, 2, 3, n and N is Each is different. For example, each electric field indicated by broken line 15 is a partial pixel Is consistent with the area of. Due to the different capacitances, each subpixel is And is activated by various different levels of voltage applied from the power supply 24. Applied The amount of voltage 24 that is applied determines the number of sub-pixels that are activated, so that their A particular gray scale of pixels consisting of sub-pixels is obtained and therefore a liquid crystal display device The gray scale ability of is obtained.   The number of partial pixels that is practical for this configuration is typically 2 to 4. Shi However, design a configuration with 5 to 20 or more partial pixels per pixel Is also good. FIGS. 3a, 3b and 3c show the structure of three partial pixels as an example of the present invention. 11 configuration, 12 partial pixel configuration 12 and 9 partial pixel configuration 13 You Figure 3a shows a "stacked" partial view in which the membrane electrodes are sequentially stacked in a rising manner. Represents the elementary composition. 3d to 3e show the configuration of electrodes 43 and 44 as 41 and 42. Various wearing methods are shown respectively. 3f-3g show configurations 41 and 42, respectively. Corresponding but partial pixel configurations 45 and 46 having pixels with wider aspect ratio Represents The configuration 47 of FIG. 3h is a structural design of three partial pixels. 4a- FIG. 4b shows a parallel-series partial pixel electrode layout with main electrode connection points 50 and 51. Indicates the 5a and 5b show pairs for pixels with parallel partial pixel electrode connections. A corresponding electrical schematic 52 and a structural schematic 53 are shown. 5c and 5d show the In the schematic diagram 54 and the structural layout 55, series-parallel with four partial pixels Represents a method. 5e and 5f, the electrical configuration 56 and the corresponding structure 57 are There is a series-parallel system with three divided pixels. Achieve specific design goals It is possible to use a combination of a serial method and a parallel method to do so. One The number of partial pixels forming a pixel may be any number, and may be circular or triangular. Pixels of any shape, form, or design such as may be formed.   When the saturation voltage is 90% and the cutoff voltage is 10%, the partial pixel The voltage for sequentially activating the sub-pixels of one pixel consisting of two is about 9 Vols, respectively. And 12 volts. In the case of three partial pixels, the starting voltage is about They are 9 volt, 13 volt and 20 volt. Partial pixel All parts of 4 pixels About 50 volts are needed to activate the pixel. That is, for one pixel As the number of subpixels inside increases, the voltage must increase significantly. One By increasing the amount of optical overlap between a partial pixel and another partial pixel, The amount of drive voltage required for start-up may be reduced, for example the saturation voltage. 80% and the cutoff voltage 20%, the overlap becomes large and 1 The amount of drive voltage to activate all subpixels of one pixel is reduced.   The equations shown below electrically analyze the operation of partial pixels. Partial pixel 1 , 2, 3, n ... N are arranged in series, and their impedance 1 /_sC₁, 1 /_sC₂, 1 /_sC₃, 1 /_sC_n, 1 /_sC_NRespectively specified by However, the subscript n indicates the number of the partial pixel of interest, and N indicates the total number of partial pixels. . Department Area A of the divided pixels 1, 2, 3, n and N₁, A₂, A₃, A_n・ ・ ・ ・ ・ ・ A_NIs one Partial pixels are designed and arranged so that they have different voltages from the adjacent partial pixels. ing. From Ohm's law, the pixel with the smallest capacitance is the most Also has a high impedance and is therefore applied to the capacitive divider network of that pixel. Get the highest percentage of the voltage that is applied. The following formula is used to activate partial pixels sequentially. Determine the required area size of the partial pixels 1, 2, 3, n and N. Applied The partial pixels 1 to N are continuously activated as the voltage increases. Voltage 24 in series Applied across the capacitive network 26. Formulas 1-8 below are 10 parts Set up to activate subpixels 1 to N at cent and 90% optical transmission point. It is intended to be measured. The specific area of each sub-pixel 1, 2, 3 and n is It is calculated by these equations. Expressions 9 to 21 are the impedance of the partial pixel and the saturation voltage. Is to confirm. Impedance Z of each partial pixel 1 to n_n-1Is K = ((V₉₀/ V_Ten) ・ Ε), V_TenAnd the parallel dielectric constant ε of the liquid crystal material 28_‖When Vertical dielectric constant ε_⊥When the ratio with and is ε, Z_n-1= KZ_nAdjacent sub-pictures according to It is shown to be associated with prime. That is,         ε = ε_‖/ Ε_⊥ Becomes   Z_n= 1 /_jwC_nAnd Z₁, Z₂, Z₃And Z_nIs the partial pixel cond Sensors 1, 2, 3 and n, respectively, and the partial pixels 1, 2, 3 and And n, and when each subpixel is not activated, that is, The voltage applied to the partial pixels of_TenWhen the In contrast, it is in series with n-1 partial pixels. ε_‖Is the "off" voltage applied to the liquid crystal ≤V_TenIs the dielectric constant of the liquid crystal when_⊥Partial pixel electrode when not This is the case where the ellipsoidal molecules are perpendicular to the electric field applied between them. ε_‖Is the oval When the child is parallel to the electric field applied between the partial pixel electrodes, that is, at both ends of the pixel "Saturation" voltage V_SATIs V₉₀It is the dielectric constant of the liquid crystal material when the above is satisfied. LCD invitation The electric body is an anisotropic material for which the minimum energy state is required. Basic plate conden The formula is C = k_eε_o(A / D) and E = 1/2 (q²/ C) is included. Where k_eIs Is the relative permittivity of a uniform isotropic dielectric between the capacitor electrodes, ε_oIs an invitation to free space Is the electric conductivity, A is the effective area of the electrodes, D is the distance between the electrodes, and q is the relationship. The amount of charge on the capacitor.   The equations shown below determine the parameters for the previously disclosed partial pixel configuration. This is a design formula for That is, By induction, However However Therefore,

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Claims (1)

[Claims]   1. Self having at least one pixel utilizing a parallel / series partial pixel electrode configuration In my own halftone liquid crystal display device,   A first conductive film having a first region;   A second region proximate to and parallel to the first membrane and aligned with the first region. An area, the second area having the same size as the first area and the second area A second conductive film located at a first distance from the first region of the first film;   A third region of the second film that is adjacent to and parallel to the second conductive film. Has a fourth region aligned with, and the fourth region has the same size as the third region. A third conductive film in which the fourth region is at a second distance from the third region of the second film. A self-referenced halftone liquid crystal display device comprising:   2. A fifth region of the third membrane proximate to and parallel to the third membrane, Has a sixth region aligned with, and the sixth region has the same size as the fifth region. The sixth region is at a third distance from the fifth region of the third conductive film. The pixel according to claim 1, further comprising an electric film.   3. A seventh region of the fourth membrane proximate to and parallel to the fourth membrane, Has an eighth region aligned with, and the eighth region has the same size as the seventh region. And the eighth region is at a fourth distance from the seventh region of the fourth conductive film at a fifth distance. The pixel according to claim 2, further comprising an electric film.   4. A ninth region of the fifth membrane, proximate to and parallel to the fifth membrane, And a tenth region aligned with the tenth region, the tenth region having the same size as the ninth region. And the tenth region is at a fifth distance from the ninth region of the fifth conductive film. The pixel according to claim 3, further comprising the conductive film of No. 6.   5. An eleventh region of the sixth membrane that is proximate to and parallel to the sixth membrane. A twelfth region aligned with the region, the twelfth region having the same size as the eleventh region. And the twelfth region is at a sixth distance from the eleventh region of the sixth conductive film. The pixel according to claim 4, further comprising a seventh conductive film.   6. A thirteenth region of the seventh membrane that is adjacent to and parallel to the seventh membrane. Has a fourteenth region aligned with the region, the fourteenth region being the same size as the thirteenth region. And the fourteenth region is at a seventh distance from the thirteenth region of the seventh conductive film. An eighth conductive film,   Adjacent to and parallel to the eighth film, a fifteenth region of the eighth film; Has sixteenth regions aligned, the sixteenth region having the same size as the fifteenth region And the sixteenth region is at an eighth distance from the fifteenth region of the eighth conductive film. A ninth conductive film,   A seventeenth region of the ninth film proximate to and parallel to the ninth film; Has an aligned eighteenth region, the eighteenth region having the same size as the seventeenth region And the eighteenth region is at a ninth distance from the seventeenth region of the ninth conductive film. The pixel according to claim 5, further comprising a tenth conductive film.   7. The first and third membranes are adhered to a first plate,   The second membrane is adhered to a second plate,   The liquid crystal material is located between the first plate and the second plate,   The first voltage electrode is connected to the first conductive film,   The second voltage electrode is connected to the third conductive film,   The aligned first and second regions form a first partial pixel of the pixel, and One   The aligned third and fourth regions form a second partial pixel of the pixel. The pixel according to claim 1.   8. The first and third membranes are adhered to a first plate,   The second and fourth membranes are adhered to a second plate,   The liquid crystal material is located between the first plate and the second plate,   The first voltage electrode is connected to the first conductive film,   The second voltage electrode is connected to the fourth conductive film,   The aligned first and second regions form a first partial pixel of the pixel,   The aligned third and fourth regions form a second partial pixel of the pixel,   The aligned fifth and sixth regions form a third partial pixel of the pixel. The pixel according to claim 2.   9. The first, third and fifth membranes are adhered to the first plate,   The second and fourth membranes are adhered to a second plate,   The liquid crystal material is located between the first plate and the second plate,   The first voltage electrode is connected to the first conductive film,   The second voltage electrode is connected to the fifth conductive film,   The aligned first and second regions form a first partial pixel of the pixel,   The aligned third and fourth regions form a second partial pixel of the pixel,   The aligned fifth and sixth regions form a third partial pixel of the pixel, and One   The aligned seventh and eighth regions form a fourth partial pixel of the pixel. The pixel according to claim 3.   10. The first, third, fifth and seventh membranes are adhered to the first plate,   The second, fourth and sixth membranes are adhered to a second plate,   The liquid crystal material is located between the first plate and the second plate,   The first voltage electrode is connected to the first conductive film,   The electrode of the second voltage is connected to the seventh conductive film,   The aligned first and second regions form a first partial pixel of the pixel,   The aligned third and fourth regions form a second partial pixel of the pixel,   The aligned fifth and sixth regions form a third partial pixel of the pixel,   The aligned seventh and eighth regions form a fourth subpixel of the pixel,   The aligned ninth and tenth regions form a fifth subpixel of the pixel, and   The aligned eleventh area and twelfth area form a sixth partial pixel of the pixel. The pixel according to claim 5, wherein   11. The first, third, fifth, seventh and ninth films are adhered to the first plate. ,   The second, fourth, sixth, eighth and tenth films are adhered to a second plate,   The liquid crystal material is located between the first plate and the second plate,   The first voltage electrode is connected to the first conductive film,   The electrode of the second voltage is connected to the tenth conductive film,   The aligned first and second regions form a first partial pixel of the pixel,   The aligned third and fourth regions form a second partial pixel of the pixel,   The aligned fifth and sixth regions form a third partial pixel of the pixel,   The aligned seventh and eighth regions form a fourth subpixel of the pixel,   The aligned ninth and tenth regions form a fifth subpixel of the pixel,   The aligned eleventh region and twelfth region form a sixth partial pixel of the pixel. ,   The aligned thirteenth and fourteenth regions form the seventh subpixel of the pixel. ,   The aligned fifteenth area and sixteenth area form an eighth partial pixel of the pixel. ,   The aligned 17th and 18th regions form the 9th partial pixel of the pixel. The pixel according to claim 6, wherein   12. The at least one pixel is a halftone liquid crystal display device. 1. The pixel according to 1.   13. Self-referenced halftone liquid crystal display device having at least one pixel By the way, each pixel is   A first conductive film having a first region;   The range increases from a positive integer greater than 1 to a positive integer indicating the total number of conductive films. When the number of enclosures is N, it is close to the (2N-3) th region of the (N-1) th conductive film. A liquid crystal display device including an N-th conductive film having a (2N-2) -th region in contact therewith. Place.   14. Self-referenced halftone liquid crystal display device having at least one pixel By the way, each pixel is   A first conductive film having a first region;   Proximity to and overlapping with the (N-1) th region of the (N-2) th conductive film (N-1) th conductivity having an (N-1) th region and an Nth region And a membrane,   The (N-1) th region overlaps, resulting in the (N-1) th partial pixel And an (N-1) th partial pixel capacitor is formed,   The Nth conductive film is close to the Nth region of the (N-1) th conductive film and Has an overlapping Nth region, and   The Nth region overlaps, resulting in the Nth partial pixel and the Nth partial Forming a pixel capacitor, and   N is a suitable integer derived from the set of complete positive integers ranging from 3 to the maximum integer. An integer, and   The maximum integer is the liquid crystal display device that represents the total number of conductive films in each pixel.   15. A first non-conductive plate,   A second non-conductive plate parallel to and proximate to the first plate When,   Each consisting of N conductive films on the first plate and the second plate. And each of said membranes on said second plate is said membrane on said first plate. Of the membrane and each of the membranes on the first plate is Two of the membranes in the group on the second plate overlap so that the membranes are in contact with each other. , Each overlapping region results in one pixel of one pixel The overlapping film forming the partial pixels and the capacitance of each partial pixel is the first film. Beginning with and ending with the Nth film in sequence, resulting in partial pixels and partial pixel capacitors A self-referenced pixel having at least one pixel electrically connected in series. Soft tone liquid crystal display device.   16. The liquid crystal material sandwiched between the first plate and the second plate is further exposed. The display device according to claim 15, further comprising:   17． The first voltage terminal is connected to the first membrane,   The second voltage terminal is connected to the Nth membrane, and   Each sub-pixel overlaps at least partially constituting each sub-pixel The display device according to claim 16, wherein the display device is activated at a specific voltage determined by the amount of matching.   18. In a gray scale liquid crystal display device having at least one pixel, Each pixel is   A first surface having a plurality of conductive elements;   A plurality of conductive elements, at a distance from the first surface and the first surface; A second surface that is substantially parallel,   Most of the conductive elements on the first side are from the two conductive elements on the second side. Overlapping at a distance, and conversely most of the conductive elements on the second surface are on the first side. Of the two conductive elements on the plane of, overlap with each other at a distance, , In series,   The overlap of each of the two conductive elements on the first side and the second side is one part. A partial pixel and a partial pixel capacitance forming a partial pixel and a partial pixel of said pixel The capacitance is electrically connected in series, and   A liquid crystal display device in which a liquid crystal material is located between the first surface and the second surface.   19. Since the partial pixel capacitance has various values, the first surface and the second surface are Applying a voltage to two conducting elements across a series of overlapping conducting elements on the plane of Part of the applied voltage is applied to both sides of each subpixel capacitance, Therefore, all partial pixels are activated, one is activated, or two or more are activated, As a result, the pixel has a grayscale capability as a function of voltage magnitude. The display device according to claim 18.   20. In a method of realizing a gray scale for pixels in a liquid crystal display device,   A first surface and a second surface that are substantially parallel to each other and separated from each other by a distance. Dividing the pixel region into a plurality of partial pixel regions in terms of   Sub-pixels such that almost any conductive element covers a pair of adjacent sub-pixel areas. Forming a first plurality of conductive elements on a first side of the region;   Partial pixel areas such that almost every conductive element covers a pair of adjacent pixel areas. Forming a second plurality of conductive elements on the second surface of the substrate, and as a result, the conductive elements on the first surface. The element and the conductive element on the second surface are overlapped with each other, and the first element on the first surface in each partial pixel region is overlapped. One conductive element and one conductive element on the second surface are one partial pixel and corresponding part Forming a pixel capacitor and forming all partial pixel capacitors of the resulting pixel. The process of being electrically connected in series,   Arranging a liquid crystal material between the first surface and the second surface.   21. Partial pixels are not activated at all or one is activated depending on the magnitude of voltage Or two or more are activated, so that the pixel has a grayscale capability as a function of voltage. The process of applying a voltage between the subpixel capacitors in series so that 21. The method of claim 20 including.   22. Having at least one pixel utilizing a parallel / series partial pixel electrode configuration In the self-referenced halftone liquid crystal display device,   A first conductive film having a first region;   A second region proximate to and parallel to the first membrane and aligned with the first region. An area, the second area having the same size as the first area and the second area A second conductive film located at a first distance from the first region of the first film;   A third region of the second film that is adjacent to and parallel to the second conductive film. Has a fourth region aligned with, and the fourth region has the same size as the third region. A third region such that the fourth region is at a second distance from the third region of the second film. A conductive film,   A fourth conductive film having a fifth region,   A sixth region adjacent to and parallel to the fourth membrane and aligned with the fifth region. An area, the sixth area having the same size as the fifth area, and the sixth area A fifth conductive film located at a third distance from the fifth region of the fourth conductive film,   A seventh region of the fifth film, adjacent to and parallel to the fifth conductive film, Has an eighth region aligned with, and the eighth region has the same size as the seventh region. A sixth conductive film in which the eighth region is at a fourth distance from the seventh region of the fifth film When,   A first voltage terminal connected to the first and fourth conductive films,   A liquid crystal display device having a second voltage terminal connected to the third and sixth conductive films. Place.