RU2393517C2 - Passive-matrix lcd and method of its control - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: passive-matrix LCD consisting of two substrates integrated into package has first isolating layer of first substrate accommodating strip-like second isolating layer. Second conducting layer and orienting layers are consecutively arranged at apices of second isolating layer. Note here that solely orienting layer is applied on second substrate. Besides first transparent conducting layer is orthogonal to strip-like second isolating layer and second conducting layer at apices of said strips. In compliance with control method, data signal is sent to strip-like electrodes formed by first conducting layer of first substrate electrode.

EFFECT: data display in real time, higher contrast of cut-in image relative to cut-out image.

3 cl, 8 dwg, 3 tbl, 4 ex

Description

The invention relates to display technologies and can be applied to information display devices in cell phones, MP-3 players, electronic notebooks, handheld and laptop computers, games, measuring equipment, etc.

Liquid crystal displays (LCDs) are widely used as various image visualization devices. Most often, LCDs use the so-called twist effect (or TN - LCD structure rotated by 90 °) (for example, M. Schadt, W. Helfrich, "Voltage Dependent Optical Activity of a Twisted Nematic Liquid Crystal", Applied Phisics Letters, v. 18 (4), pp.127-128, 1971) and the super-twist effect (or STN - LCD structure twisted through an angle of 160 ° ... 270 °) (for example, TJ Scheffer, J. Nehring, "A New Highly Multiplexable Liquid Crystal Display ", Applied Physics Letters, v. 45 (10), pp. 1021-1023, Nov. 15, 1984). These displays do not have a memory state: voltage must be continuously applied to them, the rms value of which on the switched on element should be higher than a certain threshold voltage, and on the switched off one, below this value.

This management principle causes a lot of problems. First, the maximum slope of the volt-contrast characteristic is required. This is ensured by interference (twist angle of the LCD spiral 240 °, non-coaxial arrangement of the LCD layer between polaroids, etc.). Implementation of interference conditions significantly reduces contrast and increases response times. In addition, the accumulation of voltage on the screen elements leads to an increase in the rms voltage on the off pixels. As a result, either the number of multiplexed lines of the screen is limited, or its contrast is significantly worsened.

It can be confidently stated that the classic STN has exhausted its capabilities in contrast, speed and multiplexing level. Various optimization methods due to compensators or control do not allow to achieve a high level of contrast or increase the level of multiplexing in real samples.

Currently, the optimization of passive-matrix LCD technologies is due to the use of memory effects (bistability). In this case, the recorded information is stored for a long time in the absence of voltage. If there is no frame time limit, this allows you to display any number of lines. In this case, the main thing is the difference in the amplitudes and forms of voltage during the recording of the string, and not the root mean square (for several frames) its value. Contrast and switching times are also improved because they are determined by the amplitude voltage, and not by the steepness of the WSS (volt-contrast characteristic).

To ensure bistability, a balance is necessary between the elasticity of the liquid crystal layer and the surface adhesion energy. Under certain conditions, structures with a twist of 0 ° and 360 ° will be equally stable [D.W. Berreman, W.R. Heffner, J. Appl. Phys., 52 (1981), 3032: D. W. Berreman, J. Opt. Soc. Amer, 63 (1973), 1374]; ϕ and ϕ + 2π for some fixed values of ϕ [H.S. Kwok, J. Appl. Phys., 80 (1996), 3687; T.Z. Qian, Z.L. Xie, H.S. Kwok, P. Sheng, Appl. Phys. Lett., 71 (1997), 596; Z. L. Xie, H. S. Kwok, Jap. J. Appl. Phys., 37 (1998), 2572; Z. L. Xie, H. S. Kwok, Jap. J. Appl. Phys., 84 (1998), 77]. This class of bistable displays is called 2π-BTN [D.W. Berreman, W.R. Heffner, J. Appl. Phys., 52 (1981), 3032: D. W. Berreman, J. Opt. Soc. Amer., 63 (1973), 1374]. The use of such displays limits the existence of a very narrow range of gaps, spiral pitch, temperature.

The π-BTN variant is also known, in which states with a twist of 0 ° and 180 °, otherwise called BiNem [I.Dozov, M.Nobili, G. Durand, Appl. Phys. Lett., 70 (1997), 1179]; ϕ and ϕ + π for some fixed values of ϕ [H.S. Kwok, J. Appl. Phys., 80 (1996), 3687; T.Z. Qian, Z.L. Xie, H.S. Kwok, P. Sheng, Appl. Phys. Lett., 71 (1997), 596; Z. L. Xie, H. S. Kwok, Jap. J. Appl. Phys., 37 (1998), 2572; Z. L. Xie, H. S. Kwok, Jap. J. Appl. Phys., 84 (1998), 77]. This option is technologically more complex, but possible.

The disadvantage is the strong dependence of the control signals on the thickness and pitch of the spiral of the LCD layer.

A common drawback of bistable structures is the long time required to write and erase each line. The frame length becomes too long (0.18-2.5 seconds) and prevents the display of information in real time [C.Joubert, IMI Paper Like Display Conference Issue, April 2004]. There are also technological problems (a large pre-incline angle, difficult to manufacture and unstable in time), which impede the widespread use of these structures.

Other technical solutions are known to accelerate the relaxation process to its original state.

In US patent No. 6522379 "Liquid Crystal Display Element with Zigzag Data or Scan Lines Adjacent Zigzag Edged Pixel Electrodes'" (aka Japanese patent JP No. 2002169160, aka European EP No. 1091236), G02F 1/133; G02F 1/1337, publ. February 18, 2003) for this purpose it is proposed to form sections with a twist different from the rest of the screen. This can be shading when rubbing the protruding sections, or rubbing on an existing microstructure, or volume spacers. However, in this case, relaxation occurs spontaneously and depends on random factors (temperature, gap fluctuations, defect density distribution, etc.). A similar effect is obtained under the influence of an electric field if the electrode is made of three parts: informational lateral and narrow central zigzag. Applying a voltage of different polarity to the central and alternately to the side electrodes, regions with different directions of orientation perpendicular to the broken line of the zigzag gap between the parts of the electrode are formed. These sections of another twist are the centers of return from the obtained splay structure (in this technical field, the structure with the liquid crystal molecules parallel to each other and with a small angle of inclination relative to the surface of the electrodes is usually called) to the initial bend configuration (in this technical field usually called a structure with the location of the liquid crystal molecules parallel to each other and with a small angle of inclination relative to the perpendicular to the surface of the electrodes) or vice versa. Such a design makes it possible to reduce the relaxation time by almost an order of magnitude, from 42 ms to 4-7 ms.

The disadvantages of this design include a significant reduction in light aperture with a 3-way electrode design.

Also, the device proposed in US patent No. 6512569 "Liquid crystal display device and a method of manufacture thereof, and a substrate and a method of manufacture thereof (C09K 19/02), publ. January 28, 2003. According to this patent, In order to reduce the applied voltage on the electrodes, a splay structure is formed, and between them a hybrid structure with a high angle of pretilt on one surface and a low angle on the other. In this case, the hybrid structure initiates a faster transition to the bend configuration. However, to make a display with such a sharp changing the angles of the pretilt is quite difficult.

Another option is described in US patent No. 6714276 "Liquid Crystal Display Device" (C09K 19/02). At the center of each pixel is a portion with a twist angle different from the twist angle of the LCD spiral in the rest of the area. This is ensured by the introduction of an optically active chiral additive in the composition of the LC mixture, at which the pitch of the helix P satisfies the ratio 2d ₂ <P <2d ₁ , where d ₁ is the interelectrode distance in the working part of the pixel, ad ₂ is the interelectrode distance in the non-working part of the pixel. Zone d ₂ acts as a disclination center and reduces the magnitude of the voltage at which the formation of the bend configuration occurs. After the power is cut off, both structures return to their original state.

The disadvantage of the described patent is the need to close this area with a black mask to maintain contrast and, as a result, reduce the light aperture of the pixel by the size of the zone d ₂ .

A more promising option is the one in which bistable structures are switched due to the application of electric fields of various directions: vertical and horizontal.

This management principle was first introduced by [Boyd et al, J. Appl. Letters, 36 (1980), 556], in which, for the guest-host effect, switching from a homogeneous structure with zero twist (splay) to a homeotropic, perpendicular plane of the electrodes (bend) due to the vertical field between the electrodes of both plates, and the reverse switching are described - due to the horizontal field between the electrodes of the same plate (splay-bend switching, SBS). This principle allows you to record and erase the image independently, thereby reducing switching times and frame duration. However, this display was characterized by a large thickness of the LCD layer, so the voltage was too high for practical use.

There is another solution. E.J. Acosta, MJTowlerand, HGWalton, ["The Role of Surface Tilt in the Operation of Pi-Cell Liquid Crystal Devices", July 2000, Liquid Crystals, vol. 27, pp. 977-984] and US patent 6600537 "Liquid Crystal Device" (aka European patent EP No. 1225473, aka Japanese JP No. 2002287170 and English GB No. 2371372; Int. Cl. G02F 1/133) of the same authors, in which they propose to use the proximity of energy levels to exclude the formation configurations with non-zero twist angle (including π-configurations). According to this patent, there is a fairly wide range of pre-tilt angles in the range from 30 to 60 °, when a bend configuration is formed with a higher voltage, and a splay configuration with a lower or zero voltage. The frame with this control consists of two parts - erasing zero voltage and recording high voltage. The switching time is from 3.5 to 14 ms. However, a high pre-incline angle is a serious technological problem. In addition, the stability of this angle is low, i.e. over time, it decreases and the effect disappears.

US Pat. No. 6,437,844, “Liquid Crystal display device and associated fabrication method” (G02F 1/1337; G02F 1/1335), provides a variant of this solution: high pre-tilt angles are created on the pixel-forming electrodes and lower pre-tilt angles outside the pixel. These areas outside the pixels with the splay configuration are the centers of growth of the LCD structures with the initial swirl immediately after stress relief. Since the area of each pixel surrounded by the regions of the initial configuration is small, the relaxation time is significantly reduced. Total switching time improved from standard 150 to 21-43 ms.

One embodiment of this patent is an embodiment in which protrusions with a height comparable to the thickness of the LCD layer are created on the edge of each column electrode. The orientation layer covering these protrusions and processed on the pixel side by the standard method for obtaining the orientation of LC molecules parallel to the surface forms a vertical arrangement of molecules in the central part of the layer. This increases the angle of pretilt of the molecules near the surface of the electrodes to the value necessary for the formation of a stable bend configuration.

The disadvantage of this embodiment should indicate the processing in order to create an orientation of only one side of the protrusion. The side facing the inter-pixel gap will create an arbitrary orientation of the molecules. This leads to an uneven orientation of the molecules on the side adjacent to this gap of the neighboring pixel and causes the formation of defects. In addition, standard methods of orientation by rubbing in this case are not applicable, since on most of the surface of the protrusion and adjacent surfaces, the orientation grooves will be absent due to shading, creating a chaotic orientation of the molecules.

In addition, the disadvantage of the described device is an uncontrolled relaxation process from the bend configuration being energized to the splay configuration when the voltage is turned off. This creates significant problems, since this time depends on many random factors - temperature, pitch and gap fluctuations, surface cleanliness, degree of purification of the liquid crystal, etc.

International Application (WO) No. 2005/040899 "Bistable Liquid Crystal Display" (G02F 1/133), as well as publications [Fion S.Y. Yeung, H.S. Kwok, Truly bistable twisted nematic liquid crystal display using photoalignment technology, Applied Physics Letters, vol. 83, No. 21, 24 November 2003, pp. 4291-4293; X.J.Yu, H.S. Kwok, Bistable bend-splay liquid crystal display, Applied Physics Letters, vol. 85. No. October 17, 25, 2004, pp. 3711-3713; X.J.Yu, H.S. Kwok, Bistable bend-splay LCD, SID'04 Digest, pp.875-877] offer a display design with electrically controlled bend-splay switching. The specified display consists of: a first substrate on which the first conductive layer and the first orienting layer are sequentially applied; a second substrate on which a second conductive layer and a second orienting layer are sequentially applied; and a liquid crystal layer interposed between the first and second orienting layers; which orient the liquid crystal molecules in contact with them at angles θ from 20 ° to 65 °; said liquid crystal layer is capable of forming a stable splay or stable bend configuration in the absence of voltage, and when a switching voltage is applied to it, switch between said stable splay and stable bend configurations. The specific pre-incline angle is selected from the above range so that the energies of the splay and bend configurations in the absence of voltage are approximately equal. The width of the electrodes in the described example is 4 μm, and the distance between them is 6 μm.

The electrode of one of the substrates (columnar or lowercase) is made in the form of strips, each of which is two electrodes in the form of combs inserted into each other. Applying the same voltage to both combs with respect to the opposite electrode (vertical field) provides switching from the splay configuration to the bend structure. By creating a voltage above the threshold between the combs (horizontal field), and a voltage below the threshold (for a vertical field) between both combs and the electrode of the opposite substrate, they provide reverse switching from bend to splay configuration. This design and control method provide the ability to create a passive matrix screen with a high switching speed and contrast, which does not have a limit on the number of multiplexed lines. In fact, switching times from 50 microseconds at a voltage of 85 V to 10 ms at a voltage of 10 V and a contrast ratio of 40: 1 are realized. It is indicated that the contrast value can reach 200: 1.

The disadvantage of this design is the need for a high angle of pre-incline of the molecules. On the one hand, it is quite difficult technologically. On the other hand, there is the problem of ensuring the stability of a high angle of the incline. Over time, as well as during operation or storage at high temperature (especially if these temperatures exceed the temperature of transition to an isotropic state), this angle decreases. Consequently, control voltages increase with time. Moreover, when the angle of pre-incline is reduced to 25-30 °, an intermediate twist configuration occurs and switching from splay- to bend- and then again to splay-configuration becomes impossible.

The design of a liquid crystal display with vertical-horizontal switching of the direction of the electric field according to the international application WO No. 2005/040899 is as follows. Striped conductive layers and an orientation layer are successively applied to the plate. Striped conductive layers and an orientation layer are successively applied to the plate. Between the orienting layers and is a layer of LCD material. In the initial state, the molecules are oriented at an angle of more than 45 ° to the surface, and the tilt directions at the surfaces of the plates differ by 180 °. As a result of intermolecular interaction in the central part of the layer, the molecules are in equilibrium parallel to the surface. This initial horizontal splay configuration, under the action of a voltage applied to the electrodes, is reoriented along the field lines of the field vertically, and after the cessation of the voltage supply, it is converted to a second stable state, in which the vertical orientation (bend) is maintained in the central part of the molecule. In the bend state, the LCD material does not rotate the plane of polarization of the transmitted light, in the splay state it changes it as much as possible. To visualize the polarization state, a polaroid polarizer film and an analyzer are located on the outer surfaces of the substrates.

The structure of the conductive display coatings of WO No. 2005/040899 is shown in more detail. Each matrix element is formed from row bars and column bars. To transfer from the initial splay configuration to a second stable bend configuration, a voltage is applied between the electrode and the electrode consisting of two comb electrodes inserted into each other. The width of each comb electrode and the distance between them is 4 ... 6 microns. To switch from the bend configuration to the initial splay structure, zero voltage is applied to the electrode, and the voltage “+ U” and “-U” is applied to the electrodes, so that voltage U is below the threshold of vertical deformation and voltage 2 U is above the threshold horizontal deformation. The drawing shows a typical optical response of the display according to the application WO No. 2005/040899, controlled by the above algorithm. The switching time from the on state to the off state and back on the given oscillogram is several units of milliseconds, the contrast is of the order of 50: 1.

As noted above, this design has several disadvantages. The most important of them are: low light efficiency (when the width of the comb electrode used in the example is 4 μm and the distance of 6 μm between the electrodes is reduced by 40% relative to the standard); technological problems of manufacturing displays with such small details (mass matrix LCD displays are characterized by an electrode width of 30-40 microns and intervals between them 10-20 microns); technological problems of obtaining a high angle of pre-incline and its stability over time. The latter circumstance limits the life of the display.

A known design of a passive matrix liquid crystal display and a method for controlling it are described in J.C. Kim et al. Bistable property in a splay cell with chiral additive, IMID'03 Digest, pp. 555-558; J.C. Kim et al, A Novel Liquid Crystal Display Device for Memory Mode and Dynamic Mode, IMID'05 Digest, pp. 567-570. J.C. Kim et al. The authors propose a display design with a vertical electric field switching the initial splay configuration to a vertical configuration, which, after the power supply is turned off, relaxes into a 180 ° (π) twisted structure. The latter switches to the original splay configuration by applying a horizontal field.

The display, according to this design, on one of the substrates contains a grid Indium Indium Electrode (ITO), separated from the underlying ITO layer by an SiO ₂ insulating film, and an orientation layer, which forms a pre-incline angle of 5 ° after rubbing the liquid crystal molecules in contact with it . An indium oxide electrode and an orienting layer are successively formed on the second substrate, which, after rubbing the liquid crystal molecules in contact with it, forms an angle of inclination of 5 °. The width of the electrode and the distance between them is 4 μm. Between the plates with the indicated layers there is an LC mixture with a 0 ° twist angle and the ratio of the thickness of the LCD layer d to the helix pitch P ₀ equal to 0.2.

The initial splay configuration after applying a vertical field between the lower and upper electrodes of 20 V for 0.5 s is first converted to a bend configuration, which then relaxes into a 180 ° π configuration. After applying a voltage of 20 V, duration 0.7 sec 180 °, the π configuration switches to the initial splay configuration with a zero swirl angle.

The disadvantage of this design is the long duration (up to 0.7 sec) of the applied voltage, which does not allow its use for high-speed screens. In addition, the time of return to the intermediate twisted structure depends on many uncontrollable factors, for example, temperature, uniformity of the gap, the presence of orientation defects and impurities in the gap.

Another problem is associated with small distances (4-6 microns) between horizontal electrodes. This is technologically difficult (the standard size of the inter-pixel interval is 20 ... 30 microns). In addition, the implementation of the described proposals in practice will lead to a decrease in the light aperture: at 4 μm the width of each strip and the distance between the strips from 4 μm in the work [J.C. Kim et al. Bistable property in a splay cell with chiral additive, IMTD'03 Digest, pp. 555-558; J.C. Kirn et al, A Novel LCD Device for Memory Mode and Dynamic Mode, IMID'05 Digest, pp.567-570] and 6 μm in [International Application (WO) No. 2005/040899] of the aperture (ratio of the contrast-changing part of the pixel (in in this case, 4 × 4 μm) to the total pixel area (8 × 8 or 10 × 10 μm), the relative transmittance will be 25 and 16%, respectively. Another disadvantage is that the location of the electrodes on two substrates complicates the process and increases the cost of the device .

The closest analogue prototype of the technical solution to the invention is the design of the passive-matrix liquid crystal display and the method for its control described in the application No. 2006131259, G02F 1/13, publ. 03/10/2008, claims (2 pages) - patent RU No. 2335004, consisting of two substrates connected in a package with a transparent conductive layer deposited on the inner surfaces of each of them, an insulating layer and an orientation layer, a liquid crystal substance placed inside the package, matrix elements formed at the orthogonal intersection of the transparent conductive layers of the substrates, at least on one of the substrates, the electrode has a three-dimensional structure and is made in the form of a first conductive layer of a banded configuration, thick a different insulating layer on it of a different configuration and a second conductive layer, at least a part of which is located at the tops of the thick-film insulating layer, with an orienting layer applied on top of these layers. In addition, in a passive matrix liquid crystal display, a thick film insulating layer with a second conductive layer is arranged in the space between the elements of the first conductive layer with the possibility of being used as a black mask.

A method for controlling a passive matrix liquid crystal display, which consists in sequentially supplying a gating signal with an amplitude U _S1 to the strip electrodes constituting the first conductive layer of the first substrate, and an information signal ± U _D to the electrodes formed by the conductive layer of the second substrate, the first conductive layer of the first substrate and at least part of the second conductive layer of the first substrate, located at the vertices of the thick-film insulating layer, are controlled separately, while adjacent to the the electrodes formed by the strips of the second conductive layer of the first substrate located on the pedestals supply voltage | U _D |, and the voltage U _S2 = 0 is applied to the remaining electrodes of the first substrate, including those located at the tops of the thick-film insulating layer.

The disadvantages of the data of the device and method are the inability to display information in real time, reduced light aperture and increased cost of the device.

The invention consists in the following. The problem to which the claimed technical solutions (device and method) are directed is to display information in real time with a significant increase in light aperture and lower cost, as well as to increase the contrast of the on image relative to the off.

These technical results are achieved in that in a passive-matrix liquid crystal display, consisting of two substrates connected in a package with the first transparent conductive layer deposited on the inner surface of the first substrate, the first insulating layer and the orienting layer, while only the orienting layer is applied to the second substrate, placed inside the package of liquid crystal material and matrix elements, on the first insulating layer of the first substrate, a second insulating layer is arranged in the form of strips, and on the strip x of the second insulating layer, a second conductive layer and an orientation layer are arranged in series, wherein each matrix element is formed at the orthogonal intersection of the first transparent conductive layer and the gap between two adjacent strips of the second conductive layer.

In addition, in a passive matrix liquid crystal display, the first transparent conductive layer is orthogonal to the second insulating layer and the second conductive layer arranged in strips of the second insulating layer.

These technical results are achieved in that in a method for controlling a passive-matrix liquid crystal display, which includes sequentially supplying voltage to the strip electrodes constituting the first conductive layer of the first substrate, and an information signal, voltage U _{S is} simultaneously applied to all strips of the first conductive layer of the first substrate, information the signal ± U _{D is} applied to the banded electrodes formed by the first conductive layer of the first substrate, and to include a matrix element formed on about at the horizontal intersection of the first transparent conductive layer and the gap between two adjacent strips of the second conductive layer, the voltage “-U _D ” is applied to all the strips of the second conductive layer of the first substrate, and to turn off the indicated element of the matrix, the voltage “-U _D ” is applied to the odd bands of the second conductive layer and voltage “+ U _D ” to even strips of the second conductive layer of the first substrate.

Thus, the passive matrix liquid crystal display consists of:

- of two substrates connected in a package,

- on the inner surface of the first substrate deposited the first transparent layer, the first insulating layer and the orientation layer,

- only the orienting layer is applied to the second substrate,

- a liquid crystal substance placed inside the package,

- matrix elements,

- on the first insulating layer of the first substrate, a second insulating layer is arranged in stripes;

- on the strips of the second insulating layer, a second conductive layer and an orienting layer are arranged in series;

- each matrix element is formed at the orthogonal intersection of the first transparent conductive layer and the gap between two adjacent strips of the second conductive layer;

the first transparent conductive layer is orthogonal to the second insulating layer made in the form of strips and the second conductive layer located on the strips of the second insulating layer.

According to a method for controlling a passive matrix liquid crystal display, it includes:

- sequential supply of voltage to the strip electrodes that make up the first conductive layer of the first substrate, and the information signal,

- apply voltage U _S simultaneously to all strips of the first conductive layer of the first substrate,

- the information signal ± U _{D is} applied to the banded electrodes formed by the first conductive layer of the first substrate,

- apply voltage "-U _D " to all strips of the second conductive layer of the first substrate to include a matrix element formed at the orthogonal intersection of the first transparent conductive layer,

- to turn off the matrix element, the voltage “-U _D ” is applied to the odd bands of the second conductive layer of the first substrate,

- to turn off the matrix element, the voltage “+ U _D ” is applied to the even bands of the second conductive layer of the first substrate.

The invention is illustrated by graphic materials, description and examples of specific performance.

Figure 1 shows a frontal projection of the structure of a passive-matrix liquid crystal display with electrodes on one substrate.

Figure 2 shows the design of the electrodes of a passive-matrix liquid crystal display with electrodes on one substrate in a projection from above.

In Fig.3, the design of the electrodes of the passive-matrix liquid crystal display is shown in side view.

Figure 4 shows the structural switching of the display with volumetric electrodes with the initial structure of LCD molecules twisted through 180 °. When an electric field is applied to every second electrode, the structure practically does not change. When an electric field is applied between the tops and bases of the volume electrodes, an untwisted configuration is created.

Figure 5 shows a schematic diagram of the formation of the orientation on the side faces of thick-film surface structures in a standard process (figa) and in three stages of irradiation (fig.5b).

On figa, 6b, 6C shows photographs of a passive-matrix LCD display with a standard photo-orientation process. Due to the shading of the side faces of the pedestals, the adjacent LC molecules are oriented in an arbitrary manner. An LCD structure ordered in the right direction is observed in only one third of the gap between the pedestals; in the rest, a defect in orientation is observed. Figures 6d, 6e, 6f show photographs of an LCD display during the advanced photo-orientation process of Figure 5b. It is seen that the disorientation zone is absent.

7 shows an example of a practical implementation of the display. Figa: the optical response of the sample when applying voltage U _S = 20V simultaneously to all bands of the line electrode (first conductive layer), voltage U _D = -20V to the odd bands of the second conductive layer (the sign “-” means that the signal is in antiphase with voltage U _S ), to even strips of the second conductive layer - voltage U _D = + 20 V (the sample is off). Fig.7b: the optical response of the sample when applying a voltage of U _S = 20 V simultaneously to all bands of the line electrode (first conductive layer), voltage U _D = -20 V to all the bands of the second conductive layer (sample included).

On Fig given an example of a practical implementation of the display. Optical display response with 1/44 multiplex control (1 frame “on” + 1 frame “off”),

In the drawings, the following notation:

1 - the first substrate;

2 - the first conductive layer;

3 - the first insulating layer;

4 - the second insulating layer;

5 - a second conductive layer on top of a thick film insulating layer;

6 - orientation layer on the first substrate;

7 - the second substrate;

8 - orienting layer on the second substrate;

9 - liquid crystal substance;

10 - polaroid on the outer surface of the first substrate;

11 - polaroid on the outer surface of the second substrate;

12 - matrix element.

A liquid crystal display with the location of the row and column electrodes on one of the substrates is proposed.

The specified structure is schematically depicted in figure 1. On the substrate 1 (for example, glass or plastic), the first conductive layer 2 (for example, ITO - indium oxide film mixed with tin oxide) is sequentially deposited with the desired configuration (for example, in the form of strips of a lower electrode), the first insulating layer 3 (for example, SiO ₂ - silicon oxide film). On top of the first insulating layer 3 is a second insulating layer 4 - a thick-film insulating layer 4 with a thickness of 1 ... 3 μm (for example, photoresist or polyimide). At the tops of the second thick-film insulating layer 4 are strips of the second conductive layer 5 (for example, from aluminum Al, nickel Ni or indium oxide In ₂ O ₃ ). Part of the second conductive layer 5a is located outside the second insulating thick-film layer 4, directly on the surface of the first substrate 1, and serves to contact the terminals of the control chip. For convenience of consideration, in the sequel, we consider separately even bands of the second conducting layer 5c and odd bands 5c. An orientation layer 6 is applied on top of these layers. As an orientation layer 6, for example, an SD-1 photo-orientant based on azo compounds [VGChigrinov, HSKwok, WCYip, EKPrudnikova, VMKozenkov, H. Akiyama, M. Fukuda, H. Takada, H. can be used. Takatsu, SID'01 Digest, 1170-1173; VGChigrinov, HSKwok, EKPrudnikova, VMKozenkov, Z. Ling, H. Akiyama, M. Fukuda, T. Kawara, H. Takada, H. Takatsu, SID'02 Digest, 1106-1109 VGChigrinov, HSKwok, VMKozenkov, EKPrudnikova Akiyama, H. Takada, H. Takatsu, SfD'03 Digest, 620-623], the chemical formula of which is given below:

The orientation direction of the liquid crystal molecules in contact with the SD-1 layer is determined by the direction of polarization of the incident light of the ultraviolet part of the spectrum (wavelength 365 nm) during the polymerization of the orientating layer 6. On the second substrate 7 (glass or plastic), only the orientational layer 8 is applied (for example, polyimide or, as mentioned above, photo-orientation SD-1). Molecules of liquid crystal material 9 located between the substrates 1 and 7 are oriented in the direction defined by the orienting layers 6 and 8. The orientation direction can be any. Moreover, if the orientation directions of the LCD molecules of the liquid crystal substance 9 in contact with the orienting layers 6 and 8 do not coincide with each other, a twisted structure is formed in which a smooth rotation from one direction to another is ensured. The composition of the liquid crystal material 9 may include an optically active additive, providing an additional angle of twist. As a result, the liquid crystal molecules can be twisted at any angle from 0 ° to 360 ° or more.

Polaroids 10 and 11 are located on the outer surfaces of the first and second substrates 1 and 7. One of them serves to polarize the light incident on the liquid crystal molecules, and the second is an analyzer of light transmitted through the layer of liquid crystal molecules (and converted by them).

In Fig.2, the design of the electrodes of a passive-matrix liquid crystal display with electrodes on one substrate is shown in a projection from above. The first conductive layer 2 is formed on the first substrate 1 and is a line electrode of a given configuration (for example, strips). Perpendicular to it are the strips of the first thick-film insulating layer 3, on the tops of which there are strips of the second conductive layer 5 of a given configuration (for example, in the form of strips) - a column electrode. Each element of the matrix 12 is formed at the intersection of the strip of the first conductive layer 2 (for example, the horizontal electrode) and the gap between two adjacent strips of the second conductive layer 5b and 5c (for example, the column electrode).

In Fig.3, the design of the electrodes of the passive-matrix liquid crystal display is shown in side view. On the first substrate 1, there are strips of the first conductive layer (line electrode) 2, the first thin-film insulating layer 3, and perpendicular to the lines of the line electrode is the second thick-film insulating layer 4. At the tops of the second insulating layer 4 there are strips of the second conductive layer (column electrode) 5 ( even 5b and odd 5c. At least from one edge the thickness of the second insulating layer 4 gradually decreases and in zone 5a the second conductive layer 5 is already directly on the surface of the first substrate 1 or p the first- insulating layer 3. This is necessary for the strength of the second conductive layer 5 in the junction zone (splicing) the first and second substrates 1 and 7 in the package and in the contacting zone with the control terminals of the chip. Atop layer 5 is applied to the alignment layer 6.

As noted above, the swirl angle of liquid crystal molecules between substrates 1 and 7 can be any.

Figure 4 shows the structural switching of the display with volumetric electrodes with the initial structure of LCD molecules twisted through 180 °. When an electric field is applied between the electrode 2 and only even electrodes 5b (or only odd electrodes 5c) located on the tops of the second insulating thick-film layer 4, the arrangement of the liquid crystal molecules remains almost unchanged: the molecules next to the electrodes 5b (or 5c) will reorient along the force field lines. As you move away from the electrode, the reorientation angle will decrease, but at a distance of 4 ... 7 μm, the change does not occur at all. Since most of the layer in the space between the even 5c and odd 5c bands of the second conductive layer 5 is not reoriented, the structure of the molecules between the substrates is preserved in the initial state (Fig. 4a).

If the field is applied between the first conducting layer 2 even strips 5b and odd strips 5c, then the molecules near the even strips 5b and odd strips 5c at the vertices of the second insulating thick-film layer 4 are symmetrically reoriented along the field lines of the field. As a result of the interaction of reoriented near-electrode molecules with the rest located in the space between the first conductive layer 2 on the one hand and the second conductive layer 5, all molecules in this space are oriented perpendicular to the surface of the substrate. A structure is formed between the first 1 and second 7 substrates, characterized by an angle of inclination of molecules close to 90 ° near the first substrate 1 and close to 0 ° by the angle of inclination of molecules near second substrate 7. This configuration is known as “hybrid”. If the initial configuration with a twist angle of 180 ° molecules in crossed polaroids looks like light, then the hybrid in them is observed as dark. This provides a high-contrast switching between two optical states.

An important point in the implementation of this design is the method of forming the orientation layer. Standard orientation methods are poorly suited for thick-film objects of complex configuration: because of their large thickness, orientation by rubbing or oblique spraying results in shading or disorientation zones. For this reason, it is advisable to use non-contact photo-orientation methods when forming the orientation in the proposed display (for some materials, irradiation with polarized UV light, 340 ... 370 nm, causes the orientation of the molecules, upon subsequent contact with this material, in the direction of polarization of the incident light).

Figure 5 shows a schematic diagram of the formation of the orientation on the side faces of thick-film surface structures in a standard process (figa) and in three stages of irradiation (fig.5b). On figa, 6b, 6C shows photographs of a passive-matrix LCD display with a standard photo-orientation process. Due to the shading of the side faces of the pedestals, the adjacent LC molecules are oriented in an arbitrary manner. An LCD structure ordered in the right direction is observed in only one third of the gap between the pedestals; in the rest, a defect in orientation is observed.

Figures 6d, 6e, 6f show photographs of an LCD display during the advanced photo-orientation process of Figure 5b. It is seen that the disorientation zone is absent.

7 shows an example of a practical implementation of the display.

On figa shows the optical response of the sample when applying a voltage of U _S = 20 V simultaneously to all bands of the line electrode (first conductive layer), voltage U _D = -20 V to the odd bands of the second conductive layer (the sign “-” means that the signal is in antiphase with voltage Us), to even bands of the second conductive layer - voltage U _D = + 20 V (the sample is off).

On fig.7b shows the optical response of the sample when applying a voltage of U _S = + 20 V simultaneously to all the strips of the line electrode (the first conductive layer), voltage U _D = -20 V to all the strips of the second conductive layer (the sample is included).

On figs shows the optical response of the sample in the mode of "one cycle - on, 1 cycle - off." The voltage U _S = + 20 V is supplied simultaneously to all the strips of the horizontal electrode (the first conductive layer), the voltage U _D = -20 V to the odd strips of the second conductive layer. The even bands of the second conductive layer are alternately supplied with signals U _{D with an} amplitude of “−20 V” and “+20 V”. The duration of each pulse is 5 ms, the pulse repetition period is 45 ms.). The reaction time is 1.1 ... 1.3 ms, the relaxation time is 18.0 ... 18.7 ms.

On Fig given an example of a practical implementation of the display - the optical response of the display with multiplex control (32 lines; 1 frame "on" + 1 frame "off"). The reaction time is just over 9 ms, and the relaxation time is approximately 21.5 ms. Contrast is approximately (160 ... 170): 1.

The invention is illustrated by the following example of a real design.

Example 1

The first conductive layer on one of the glass substrates is a strip of the line electrode of the matrix, made of a standard oxide-indium film doped with tin oxide (ITO). Film thickness 0.12 microns. Strip width 0.10 mm, spacing between stripes: 0.025 mm. An ITO film was coated with an SiO ₂ insulating coating 0.08 μm thick. Perpendicular to the strips of the line electrode, bands of the FP-383 photoresist are formed with a width of 0.025 μm and a thickness of 1.7 ... 1.9 μm. On the upper part of the bands of the photoresist is a second conductive layer of aluminum, a thickness of 0.5 ... 0.7 μm. Thus, the total height of the strips of a thick-film insulating layer with an electrode at the apex is 2.2 ... 2.6 μm. The width of the aluminum strips is equal to the width of the bands of the photoresist (this is ensured by the manufacturing technology - the formed aluminum strips are the mask during plasma-chemical etching of the photoresist) and is 0.025 μm. An orientation layer of SD-1 photoorientant 20 ... 50 nm thick is applied on top of these bands. On the second substrate there is only an orientation layer of the photo-orientation SD-1 of the same thickness.

The plates are packaged, the space between the plates is filled with liquid crystal material MLC-6295 + 0.5% ZLI-811 from Merck (Germany) with an equilibrium helix pitch of P ₀ = 14 μm. The thickness of the liquid crystal layer is 6.5 microns. The swirl angle of the liquid crystal molecules was 180 °. Crossed polarizers were located on the outer surfaces of the display, the polarization axis of the input polaroid was 0 ° with the direction of orientation of the input molecules.

The display of this design works as follows (see figure 4). Since the molecules of the liquid crystal substance, which were initially oriented parallel to the surface, are twisted through 180 °, the molecules in the center of the layer are rotated by an angle of 90 ° relative to the molecules adjacent to the substrates. (in this case, due to the small thickness of the liquid crystal layer above the thick-film coating, the molecules above it have zero twist - this is a well-known fact in the industry that the twist angle depends on the thickness of the LCD layer; it has no relation to the essence of this proposal). If voltage U _{1 is} applied between the conductive layer 2 and one (for example, 5b) of a pair of second conductive layers 5b and 5c located on the tops of the first thick-film insulating layer 4, the distortion of the structure will be negligible (Fig. 4a). If a voltage U _{2 is} applied between the first conductive layer 2 and both second conductive layers 5b and 5c located on the vertices of the second thick film insulating layer 4, then the molecules of the liquid crystal substance 9 (except for those directly contacting the surface) are reoriented to the vertices of the second thick film insulating layer 4 along the field lines. The angle of inclination of the molecules near the vertices of the second insulating layer 4 will be maximum. As you move away from the vertices of the second insulating layer 4, the angle of inclination of the LCD molecules will decrease. In this case, the tilt angles from different sides of the apex of the second insulating layer 4 will change symmetrically, but opposite in sign. In other words, in the space between the vertices of the second insulating layer 4, the twisting ability of one part of the LCD molecules will be balanced by the twisting ability of the opposite sign in the other part. As a result, the LCD structure will spin up to 0 ° (Fig. 4b). Thus, in crossed polarizers there is a switch from a light state with a 180 ° swirl to a dark state, from 0 °.

There are other possible variations in the structure, for example, from 270 ° of the original to 90 °. For this, it is enough that the orientation direction on the substrate 7 is an angle of 90 °, and the optically active additive provides the equilibrium pitch of the LCD spiral P ₀ , satisfying the inequality:

,

,

where d is the thickness of the layer of liquid crystal substance 11 between the first and second substrates 1 and 7.

For comparison, a standard design display was made (on one of the substrates, ITO line electrode strips 0.10 mm wide were formed, the intervals between the strips were 0.025 mm. On the second substrate 7, ITO column electrode strips 0.09 mm wide were formed (perpendicular to the line strips), the gaps between stripes - 0.025 mm. Orientant - SD-1 photo-orientation 20–50 nm thick. The thickness of the LCD layer and its material are similar to those used above.

Table 1 The contrast of the sign relative to the background, p.u. Multiplexing level Standard sample Experimental sample static 6.3: 1 20.8: 1 1: 8 5.1: 1 17.1: 1 1:16 3.0: 1 12.4: 1

table 2 The list of basic technological operations for standard and proposed designs No. p / p the name of the operation Standard technology with electrodes on both plates Proposed technology with electrodes on one plate one Chemical treatment 2 plates 2 plates 2 ITO spraying 2 plates 1 plate 3 Formation of a given ITO topology (for example, bands) 2 plates 1 plate four Insulating layer 2 plates 1 plate (if necessary) 5 Application of a thick film layer (photoresist) - 1 plate 6 Spraying a second conductive layer (e.g. aluminum) - 1 plate 7 The formation of a given topology on the second conductive layer (for example, strips) with the simultaneous etching of the thick film layer of the photoresist - 1 plate 8 Chemical cleaning before applying orientant 2 plates - 9 Drawing a orientant 2 plates 2 plates TOTAL OPERATIONS 12 9 ... 10

The threshold voltage in the sample manufactured by standard technology was 2.8 V, the saturation voltage was 3.6 V. Accordingly, the slope of the voltage-contrast characteristic is 1.29, and the expected level of multiplexing is 1:16. As can be seen from table 1, the image contrast of the experimental sample exceeds the standard contrast by 3 ... 4 times. In addition, the light aperture is (100 μm × 100 μm) / (125 μm × 125 μm) × 100% = 39%. Thus, it is 1.5 ... 2.4 times higher than that of the previously described analog structures.

The decrease in the complexity of manufacturing and the price of a passive matrix screen with electrodes on one plate compared to the standard design with electrodes on both substrates is determined primarily by the fact that in the standard design the number of critical operations is 12, and in the proposed design by 17 ... 25% less (see table 2).

Technologically, the most difficult moment is the creation of a defect-free orientation on the surface of the matrix element, in the space between adjacent vertices of the insulating layer.

In the standard orientation process, either rubbing the polymer layer on the substrate, or oblique deposition of a material of the type SiO ₂ , or photo orientation by irradiation of a photosensitive polymer material of the type SD-1 with polarized light can be used.

The first two processes on the bulk elements of the matrix give orientation defects associated with shading. For example, when rubbing a substrate structure similar to that shown in Fig. 1, perpendicular to the direction of the vertices of the second thick-film insulating layer of pedestals, the width of the non-oriented region reached 4 mm. The only possible direction of orientation during rubbing or inclined spraying is the direction along the vertices of the second thick-film insulating layer - pedestals. Any deviation from this direction will lead to the appearance of defective homogeneity regions. However, the direction of movement of the fiber during rubbing (the most common and cheapest method of orientation) always has a certain spread of the order of ± 5 ... 20 °, which does not allow to obtain a uniform orientation on bulk surfaces. There are other problems, for example, restrictions on the diameter of the fiber of the rubbing material: it should have a diameter several times smaller than the size of the matrix element - pixel, etc.

The most promising for orientation on surfaces with volumetric elements of the matrix on the substrate are photoorientants, for example, the already mentioned SD-1. In our case, the substrate with volume electrodes 12 and the SD-1 orientation layer was irradiated with vertically incident linearly polarized light from a conventional 365 nm wavelength power of 10 ... 20 mJ / cm ² (Fig. 9a). If the direction of polarization is parallel to the direction of the strips of the thick-film insulating layer, the molecules of the liquid crystal adjacent to SD-1 are oriented parallel to the surface and perpendicular to the direction of the strips of the thick-film insulating layer. If the polarization direction is perpendicular to the direction of the strips of the thick-film insulating layer, the liquid crystal molecules are oriented parallel to the surface of the substrate and parallel to the direction of the strips of the thick-film insulating layer. However, in this case, the lateral faces of the strips of the thick-film insulating layer turn out to be non-oriented, as a result of which the molecules of the liquid crystal substance on a significant part of the matrix element have a chaotic arrangement.

Example 2

A passive matrix liquid crystal display made of two glass substrates, one of which is a successively deposited layer: an indium oxide conductive film (ITO) 120 nm thick, an insulating layer of SiO ₂ (100 nm thick); thick film strips of photoresist FP-383 with a thickness of 1.5 ... 1.7 μm with light-blocking aluminum electrodes (thickness 0.9 μm) over these thick-film insulating layers. The width of the strips of thick-film insulating layers with an Al-film on top was 20 ... 25 microns, and the distance between adjacent strips of thick-film insulating layers was 90 ... 95 microns. The inner surface of both substrates was coated with a photoorienting material based on SD-1 azo dye (20-50 nm thick). The orienting layer was applied by centrifugation of a 1% solution of SD-1 in dimethylformamide and annealed at a temperature of 140 ° C.

The optical exposure scheme (wavelength 360 ... 365 nm) is shown in figa. The substrates were illuminated so as to form a parallel orientation in the cell along the direction of the thick-film insulating layer. The material MLC-6295 (Merck, Germany) with an optically active additive ZLI-811 (Merck, Germany) was used as a liquid-crystalline substance to obtain the equilibrium pitch of the LCD helix P ₀ = 100-140 μm. The thickness of the LCD layer was 6 ... 7 μm.

Figure 6 shows photographs of the formed structures in an Olympus VIZ microscope with a JVC-TK-128L video camera. Photos were taken with the polaroids arranged in the crossed (Fig.6a), parallel (Fig.6b) and in the polaroids at a 45 ° angle (Fig. .6s). It is seen that the misorientation effect of the side walls affects a distance of up to 30 μm from them (up to 1/3 of the interval by the vertices of the thick-film insulating layer) on each side. The contrast of such a display, even in the ideal case, will not exceed (1.5 ... 2.0): 1.

Fig. 5b shows an optical diagram of the photo-orientation process used in the present invention. At stage I, a plate with volumetric electrodes is illuminated at an angle of 45 ° with light polarized in the plane of the figure. This ensures orientation along the direction of the strips of the thick-film insulating layer on one of the side faces of the bulk electrode. At stage II, a plate with volumetric electrodes rotates 180 ° and is illuminated under the angle of 45 ° with light polarized in the plane of the figure. This ensures orientation along the direction of the strips of the thick-film insulating layer on other side faces of the bulk electrode. At stage III, the plate is illuminated by vertically incident linearly polarized light polarized in the plane of the picture. This ensures orientation on the surface of the matrix element. Thus, a structure is formed that is uniformly oriented parallel to the surface along the direction of the strips of the thick-film insulating layer.

Example 3

The substrate of the display structure according to Example 2 is irradiated in three stages, as described above. The second substrate is made by vertical irradiation with polarized light. The orientation and type of LCD correspond to those indicated in Example 2. Figs. 6d-6f show photographs of the formed structures in an Olympus BH3 microscope with a JVC-TK-1281 video camera. The photographs were taken with the crossed (Fig.6d), parallel (Fig.6e) arrangement of polaroids and in parallel polaroids with the arrangement of the matrix element at an angle of 45 ° (Fig.6f). It can be seen that with this method of manufacturing a display with volumetric electrodes, misorientation is absent.

With this orientation method, the angle of the pre-incline of the liquid crystal molecules can be adjusted. To this end, the substrate during irradiation in the first two stages is further oriented at a small (from 2 ... 5 ° to 20 ... 22 °) azimuthal angle. As a result, if necessary, the molecules in the entire volume of the liquid crystalline substance between the strips of thick-film insulating layers can have a nonzero pretilt angle.

The following are examples of the practical implementation of the display according to this invention.

Example 4

This example demonstrates the ability to control the display using volumetric electrodes made on one plate. The display consists of two glass plates with a thickness of 1.0 mm. A transparent indium oxide layer 120 nm thick and an 80 nm thick SiO ₂ insulating layer are successively deposited on the inner surface of one of them. On the insulating layer in the intervals between the strips of the transparent conductive layer are strips of photoresist FP-383 1.7-1.9 microns high. The width of each strip is 20 ... 25 microns, the distance between the strips is 90 ... 95 microns. At the tops of the strips is a layer of aluminum with a thickness of 0.5 ... 0.7 μm. Thus, the total height of the strips of thick-film insulating layers with a conductive layer is 2.2 ... 2.6 μm. The indium oxide and aluminum layers are controlled separately. The aluminum conductive layer at the tops of the thick-film insulating layer is made in the form of two combs inserted into each other, controlled independently. On top of this structure, a layer of SD-1 photoorientant 20 ... 50 nm thick was deposited, processed in such a way as to orient the liquid crystal molecules along the bands. On the inner surface of the second substrate, a layer of SD-1 photoorientant 20 ... 50 nm thick is applied, processed in such a way as to orient the liquid crystal molecules along the bands. The pre-incline angle was 2 ... 5 °. The gap between the plates was provided by calibrators in the form of fiberglass and is 4.5 microns. The material MLC-6096 + 1.0% ZLI-811 from Merck (Germany) with an equilibrium helix pitch of 10 μm was used as a liquid crystal substance. The swirl angle of the liquid crystal molecules was 180 °. Crossed polarizers were located on the outer surfaces of the display, the polarization axis of the input polaroid was 0 ° with the direction of orientation of the input molecules.

The display was controlled by supplying voltage between the indium oxide and aluminum conductive layers. In this case, one of the conductive layers made in the form of an aluminum comb was constantly under voltage U = 20 V, the second conductive layer made in the form of an aluminum comb was supplied with either zero voltage - off state (Fig. 7a) or the same voltage U = 20B (Fig.7b). 7 c shows the optical response of the display when switching between on and off states, characterizing the dynamic properties of the structure. The pulse duration is 5 ms, the pulse repetition period is 45 ms. The contrast between on and off is 168: 1; reaction time - 1.1 ms; relaxation time - 18.7 ms.

Table 3 V ° In the direction of the combs (N), ° -60 -45 -thirty -twenty -10 0 10 twenty thirty 45 60 45 18: 1 thirty 28: 1 twenty 125: 1 10 78: 1 0 8: 1 20: 1 63: 1 72: 1 80: 1 130: 1 125: 1 115: 1 85: 1 28: 1 11: 1 -10 73: 1 -twenty 17: 1 -thirty 7: 1 -45 5: 1

The angular characteristics of the display according to this invention in the horizontal (H) and vertical (V) directions are presented in Table 3. When the deviation in the horizontal direction is more than ± 50 °, the transmittance drops sharply due to the shading effect. However, as can be seen from table 2, the viewing angle according to the criterion CR≥5: 1 exceeds ± 60 ° horizontally and ± 45 ° vertically. According to these indicators, the display according to this invention exceeds the standard active-matrix displays on a twist effect.

On Fig shows the optical response of the display with multiplex control (32 lines; 1 frame "on" + 1 frame "off"). The reaction time is just over 9 ms, and the relaxation time is approximately 21.5 ms. Contrast exceeds 150: 1.

It should be noted that the location of the second layer of the volume electrode in the space between the matrix elements allows you to use it as a black mask that closes the interelectrode gaps. This simplifies the technology and allows the use of opaque materials, such as aluminum or nickel, as a conductive coating on the tops of a thick film insulating layer.

As the material of the thick-film insulating layer, various photoresists, polyimides, and other insulating materials can be used.

As an orienting layer on a plate that does not have a volume electrode, standard materials can be used - polyimides during rubbing or silicon oxide with inclined spraying.

Any composition containing adsorbers having a stable dichroic range in the wavelength range of 200 ... 450 nm can be used as a photo-orientation.

There are no special requirements for the liquid crystal material used in this invention. Any liquid crystal can be used in this device.

Other control options are possible.

The gray scale formation methods in this design and its control methods are similar to those used in standard passive-matrix screens. This is amplitude or pulse width modulation. It is also possible to use several matrix elements for spatial halftone formation (spatial modulation) or to generate a transmission level average over several frames (half-frame modulation).

The present invention provides a design and a method for controlling a passive matrix LCD screen with vertical-horizontal switching, increased light aperture and reduced charge accumulation on image elements. The invention is based on nematic LCD structures and photo orientation technology. Any substrate materials may be used, including glass and plastic.

Claims (3)

1. A passive matrix liquid crystal display consisting of two stacked substrates with the first transparent conductive layer deposited on the inner surface of the first substrate, the first insulating layer and the orienting layer, while only the orienting layer of the liquid crystal substance and elements placed inside the packet is deposited on the second substrate matrix, characterized in that on the first insulating layer of the first substrate there is a second insulating layer in the form of strips, and on the strips of the second insulating layer the second conductive layer and the orienting layer are sequentially laid, wherein each matrix element is formed at the orthogonal intersection of the first transparent conductive layer and the gap between two adjacent strips of the second conductive layer. 2. The passive matrix liquid crystal display according to claim 1, characterized in that the first transparent conductive layer is orthogonal to the second insulating layer made in the form of strips and the second conductive layer located on the strips of the second insulating layer. 3. A method for controlling a passive matrix liquid crystal display, which includes sequentially supplying voltage to the strip electrodes constituting the first conductive layer of the first substrate, and an information signal, characterized in that voltage U _{S is} applied simultaneously to all the strips of the first conductive layer of the first substrate, the information signal ± U _{D is} supplied to the banded electrodes formed by the first conductive layer of the first substrate, and to include a matrix element formed at the orthogonal intersection of the first transparent conductive layer and the gap between two adjacent strips of the second conductive layer, apply voltage
“-U _D ” to all the strips of the second conductive layer of the first substrate, and to turn off the indicated matrix element, the voltage “-U _D ” is applied to the odd bands of the second conductive layer and the voltage “+ U _D ” to even strips of the second conductive layer of the first substrate.

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