JP2021511542A - Electro-optic displays and how to drive them - Google Patents

Abstract

Various methods for driving an electro-optic display to reduce visible artifacts are described. Such a method involves driving an electro-optical display that has multiple display pixels and is controlled by the display controller, the display controller being associated with a host for providing operational instructions to the display controller. Updates the display with the first image, updates the display with the second image following the first image, and processes the first image and the image data associated with the second image. And identify display pixels with edge artifacts, generate image data associated with the identified pixels, store image data-related pixels with edge artifacts in memory locations, and erase edge artifacts. Can include initiating a waveform for.

Description

The present invention relates to a method of driving an electro-optical display. More specifically, the present invention relates to driving methods for reducing pixel edge artifacts and / or image residues in electro-optical displays.

Electro-optic displays typically have a backplane, each of which is provided with multiple pixel electrodes that define one pixel of the display. Traditionally, a large number of pixels, usually a single common electrode extending over the entire display, is provided on the opposite side of the electro-optic medium. Individual pixel electrodes can be driven directly (ie, separate conductors can be provided for each pixel electrode), or pixel electrodes will be familiar to those skilled in the art of backplane technology in an active matrix fashion. Can be driven by. Since adjacent pixel electrodes will often be at different voltages, they must be separated by a gap between pixels of finite width to avoid electrical short circuits between the electrodes. At first glance, it can be considered that the electro-optic medium that overlaps these gaps will not switch when the drive voltage is applied to the pixel electrodes (in fact, it is often some non-stable, such as liquid crystal). As is the case with electro-optic media, black masks are typically provided to hide these non-switching gaps), but for many bistable electro-optic media, the medium that overlaps the gap is known as "blooming". It switches depending on the phenomenon.

Blooming refers to the tendency for the application of a driving voltage to a pixel electrode to cause a change in the optical state of an electro-optical medium over a size larger than the physical size of the pixel electrode. Excessive blooming should be avoided (for example, in a high resolution active matrix display, the application of a drive voltage to a single pixel will be adjacent to some, as this will reduce the effective resolution of the display. A controlled amount of blooming is often useful, although it is not desired to cause a switch across the area covering the pixel). For example, consider a black electro-optic display on a white background that displays numbers using a conventional 7-segment array of seven directly driven pixel electrodes for each number. For example, when zero is displayed, the six segments are turned black. In the absence of blooming, the gap between the six pixels will be visible. However, by providing a controlled amount of blooming, for example, as described in 2005/0062714 (Patent Document 1) above, the gaps between pixels are changed to black, which is more visual. Can bring beautiful numbers to. However, blooming can lead to a problem described as "edge afterglow".

The blooming area is not uniformly white or black, but is typically a transition zone in which the color of the medium transitions from white to black through various shades of gray as it travels across the blooming area. Therefore, the edge afterglow will typically be an area of various shades of gray rather than a uniform gray area, but in particular the human eye assumes that each pixel is pure black or pure white. It can still be visible and unpleasant because it has the ability to detect gray areas in a monochromatic image that is made.

In some cases, asymmetric blooming can contribute to edge afterglow. "Asymmetric blooming" is used in some electro-optical media (eg, copper chromate / titania encapsulated electrophoresis media as described in US Pat. No. 7,002,728). Refers to a phenomenon in which blooming is "asymmetric" in the sense that greater blooming occurs during the transition from one extreme optical state to the other extreme optical state, and is described in this patent. In the medium, the blooming during the black-white transition is typically greater than that during the white-black transition.
Therefore, a driving method capable of reducing the afterglow or blooming effect is desired.

International Publication No. 2005/0062714 U.S. Pat. No. 7,002,728

Thus, in one aspect, a method of driving an electro-optical display having multiple display pixels and controlled by the display controller, the display controller is associated with a host for providing operational instructions to the display controller. The method is to update the display with the first image, update the display with the second image following the first image, and the image data associated with the first image and the second image. Process, identify display pixels with edge artifacts, generate image data associated with the identified pixels, store image data-related pixels with edge artifacts in memory location, and erase edge artifacts It may include initiating a waveform to do so.

In another embodiment, the subject matter raised herein provides a method of driving an electro-optical display having multiple display pixels. The method is to update the display with the first image, to identify the display pixels with edge artifacts after the first image update, and to identify the waveforms designed to remove the artifacts to the identified pixels. Includes applying and updating another image on the display. In some embodiments, the method may also include determining the gray tone transition of display pixels between the first image and the second image. In some other embodiments, the method determines display pixels that have a different gray tone than at least one of their basic adjacent pixels and flags the identified pixels in memory associated with the display controller. It can include attaching.

FIG. 1 illustrates a circuit diagram representing an electrophoresis display.

FIG. 2 illustrates a circuit model of the electro-optical imaging layer.

FIG. 3a illustrates an exemplary special pulse-to-edge elimination waveform for a pixel undergoing a white-white transition.

FIG. 3b illustrates an exemplary special DC non-equilibrium pulse for eliminating white edges on pixels undergoing a white-white transition.

FIG. 3c illustrates an exemplary special fully white / white drive waveform.

FIG. 4a illustrates an exemplary special edge-erasing waveform for a pixel undergoing a black-black transition.

FIG. 4b illustrates an exemplary special full black / black drive waveform.

FIG. 5a illustrates a screenshot of a display with a blooming or afterglow effect.

FIG. 5b illustrates another screenshot of a display with blooming or afterglow effect reduction applied according to the subject matter raised herein.

FIG. 6 illustrates a sample global edge elimination (GEC) waveform.

The present invention relates to a method of driving an electro-optical display, particularly a bistable electro-optical display, and an apparatus for use in such a method. More specifically, the present invention relates to driving methods that may allow reduction of "afterglow" and edge effects, as well as reduction of blinking in such displays. The present invention is not exclusive, but in particular, particle-based electricity in which one or more types of charged particles are present in a fluid and they are moved through the fluid under the influence of an electric field, changing the appearance of the display. Intended for use with electrophoretic displays.

The term "electro-optics" is used in its conventional sense in the field of imaging technology, as applied to materials or displays, with at least one material having different display states with different optical properties. Yes, as used herein to refer to a material that is altered from its first to its second display state by the application of an electric field to the material. Optical properties are typically colors that are perceptible to the human eye, but for displays intended for optical transmission, reflectance, luminescence, or machine reading, reflections of electromagnetic lengths outside the visible range. It can be another optical property such as pseudocolor in the sense of change in rate.

The term "gray state", as used herein in its traditional sense in the field of imaging technology, refers to a state intermediate between the optical states of two extreme pixels, not necessarily black and white. It does not mean a transition between extreme states. For example, some E Ink patents and published applications referenced below are electrophoretic displays whose extreme states are white and dark blue, just as the intermediate "gray state" is actually light blue. Is explained. In fact, as already described, the change in optical state may not be a change in color at all. The terms "black" and "white" can be used hereafter to refer to the two extreme optical states of a display and are usually not strictly black and white, such as the aforementioned white and dark. It should be understood as including the blue state. The term "monochromatic" can be used hereafter to describe a drive scheme that drives a pixel into only those two extreme optical states, without intervening gray states.

Some electro-optic materials are solid in the sense that the material has a solid outer surface, but the material can often have an internal liquid or gas filled space. Such a display using a solid-state electro-optical material may be referred to herein as a "solid-state electro-optical display" for convenience. Thus, the term "solid electro-optical display" includes rotating bicolor member displays, encapsulated electrophoresis displays, microcell electrophoresis displays, and encapsulated liquid crystal displays.

The terms "bistable" and "bisstability" are, in their conventional sense in the art, a display comprising a display element having at least one different optical property, a first and a second display state. , A first or second display state, using an address pulse of finite duration to drive any given element and then display after the address pulse ends. As used herein, it refers to a display in which that state lasts at least several times, for example, at least four times, the minimum duration of an address pulse required to change the state of an element. In US Pat. No. 7,170,670, some grayscale-enabled particle-based electrophoretic displays are stable not only in their extreme black and white states, but also in their intermediate gray states. And the same has been shown to apply to some other types of electro-optical displays. This type of display is appropriately referred to as "multistable" rather than bisstable, but for convenience, the term "bisstable" is used herein to cover both bisstable and multistable displays. Can be used.

The term "impulse" is used herein in its conventional sense of integrating voltage over time. However, some bistable electro-optic media act as charge transducers, for which the alternative definition of impulse is the integration of current over time (equal to the total charge applied). , Can be used. A proper definition of impulse should be used, depending on whether the medium acts as a voltage-time impulse transducer or a charge impulse transducer.

Much of the discussion below focuses on how to drive one or more pixels in an electro-optic display through a transition from an initial gray level to a final gray level (which may or may not differ from the initial gray level). Will hit. The term "waveform" will be used to indicate the curve of the entire voltage over time, which is used to bring about the transition from a particular initial gray level to a particular final gray level. Typically, such a waveform would have multiple waveform elements. That is, if these elements are essentially rectangular (ie, if a given element has a constant voltage application over a period of time), the elements are called "pulses" or "drive pulses". It can be. The term "driving scheme" refers to a set of waveforms sufficient to bring about any possible transition between gray levels for a particular display. The display may utilize more than one drive scheme. For example, U.S. Pat. No. 7,012,600, supra, may need to be modified depending on parameters such as the temperature of the display or the amount of time it has been in operation during its lifetime, and therefore the drive scheme may need to be modified. , Teach that the display can be provided with a plurality of different drive schemes to be used at different temperatures and the like. The set of drive schemes used in this way may be referred to as the "set of related drive schemes". As described in some of the MEDEOD applications mentioned above, it is possible to use two or more drive schemes simultaneously in different areas of the same display, and a set of drive schemes used in this way. Can be referred to as a "set of simultaneous drive schemes".

Several types of electro-optical displays are known. One type of electro-optical display is, for example, US Pat. Nos. 5,808,783, 5,777,782, 5,760,761, 6,054,071 and 6,055. It is a rotating bicolor member type as described in 091, 6,097,531, 6,128,124, 6,137,467, and 6,147,791 (this). The type of display is often referred to as a "rotating bicolor ball" display, but in some of the patents described above, the term "rotating bicolor member" because the rotating member is not spherical. Is preferable as a more accurate one). Such displays use a large number of small bodies (typically spherical or cylindrical), the small body having two or more compartments with different optical properties and an internal dipole. These bodies are suspended in vacuoles filled with liquid in the matrix, and the vacuoles are filled with liquid so that the bodies rotate freely. The appearance of the display is altered by applying an electric field to it, thus rotating the body to various positions and varying the position of the body compartments seen through the visible surface. This type of electro-optical medium is typically bistable.

Another type of electro-optical display comprises an electrochromic medium, eg, an electrode formed at least partially from a semiconductor metal oxide, and multiple dyeing molecules attached to the electrode that are capable of reversible color change. An electrochromic medium in the form of a nanochromic film is used. For example, O'Regan, B. et al. , Et al. , Nature 991, 353, 737, and Wood, D. et al. , Information Display, 18 (3), 24 (March 2002). In addition, Bach, U.S.A. , Et al. , Adv. Mater. , 2002, 14 (11), 845. This type of nanochromic film is also described, for example, in US Pat. Nos. 6,301,038, 6,870,657, and 6,950,220. This type of medium is also typically bistable.

Another type of electro-optical display was developed by Philips, Hayes, R. et al. A. , Et al. It is an electrowetting display described in "Video-Speed Electronic Paper Based on Electrowetting", Nature, 425,383-385 (2003). U.S. Pat. No. 7,420,549 shows that such electrowetting displays can be bistable.

A type of electro-optical display that has been the subject of intensive research and development interest for many years is a particle-based electrophoretic display in which multiple charged particles move through a fluid under the influence of an electric field. Electrophoretic displays can have the attributes of good brightness and contrast, wide viewing angle, state bistability, and low power consumption when compared to liquid crystal displays. Nonetheless, long-term image quality issues with these displays hinder their widespread use. For example, the particles that make up an electrophoretic display tend to settle, resulting in an inadequate usable life of these displays.

As mentioned above, the electrophoresis medium requires the presence of fluid. In most prior art electrophoresis media, this fluid is a liquid, but the electrophoresis medium can also be produced using gaseous fluids (eg, Kitamura, T., et al. Electrical toner). See mobile for electretic paper-like display, IDW Japan, 2001, Paper HCS1-1, and Yamaguchi, Y., et al., Toner displey using fluid four-! Similarly, see U.S. Pat. Nos. 7,321,459 and 7,236,291. Such gas-based electrophoresis media are, for example, liquid-based due to particle settling when the medium is used in a vertical plane arrangement and in an orientation that allows such settling. It is considered to be susceptible to the same types of problems as electrophoresis media. In fact, particle settling is more gas-based electricity than liquid-based electrophoretic media because the lower viscosity of the gaseous suspended fluid allows for faster settling of electrophoretic particles compared to the viscosity of the liquid. It is considered to be a serious problem in the electrophoresis medium.

Numerous patents and applications transferred to or in the name of Massachusetts Institute of Technology (MIT) and E Ink Corporation describe various techniques used in encapsulated electrophoresis and other electro-optical media. ing. Such encapsulated media include a large number of small capsules, each of which contains an internal phase containing particles that are electrophoretically movable in the fluid medium and a capsule wall that surrounds the internal phase. And have. Typically, the capsules themselves are retained within a polymer binder that forms a cohesive layer located between the two electrodes. The techniques described in these patents and applications include:

(A) Electrophoretic particles, fluids, and fluid additives (see, eg, US Pat. Nos. 7,002,728 and 7,679,814).

(B) Capsules, binders, and encapsulation processes (see, eg, US Pat. Nos. 6,922,276 and 7,411,719).

(C) Microcell structures, wall materials, and methods of forming microcells (see, eg, US Pat. Nos. 7,072,095 and 9,279,906).

(D) Methods of filling and sealing microcells (see, eg, US Pat. Nos. 7,144,942 and 7,715,088).

(E) Films and subassemblies containing electro-optic materials (see, eg, US Pat. Nos. 6,982,178 and 7,839,564).

(F) Backplanes, adhesive layers, and other auxiliary layers, as well as methods used in displays (see, eg, US Pat. Nos. 7,116,318 and 7,535,624).

(G) Color formation and color adjustment (see, eg, US Pat. Nos. 7,075,502 and 7,839,564).

(H) Application of displays (see, eg, US Pat. Nos. 7,312,784 and 8,009,348).

(I) Non-electrophoretic displays as described in US Pat. No. 6,241,921 and US Patent Application Publication No. 2015/0277160, and application of non-display encapsulation and microcell techniques (eg, US Pat. (See Publication Nos. 2015/0005720 and 2016/0012710)

(J) Method of driving the display (eg, US Pat. Nos. 5,930,026, 6,445,489, 6,504,524, 6,512,354, 6,531, 997, 6,753,999, 6,825,970, 6,900,851, 6,995,550, 7,012,600, 7,023,420 , No. 7,034,783, No. 7,061,166, No. 7,061,662, No. 7,116,466, No. 7,119,772, No. 7,177,066, No. 7,193,625, 7,202,847, 7,242,514, 7,259,744, 7,304,787, 7,321,794,7, 327,511, 7,408,699, 7,453,445, 7,492,339, 7,528,822, 7,545,358, 7,583 251 and 7,602,374, 7,612,760, 7,679,599, 7,679,813, 7,683,606, 7,688,297 , No. 7,729,039, No. 7,733,311, No. 7,733,335, No. 7,787,169, No. 7,859,742, No. 7,952,557, No. No. 7,965,841, No. 7,982,479, No. 7,999,787, No. 8,077,141, No. 8,125,501, No. 8,139,050, No. 8, 174,490, 8,243,013, 8,274,472, 8,289,250, 8,300,006, 8,305,341, 8,314, 784, 8,373,649, 8,384,658, 8,456,414, 8,462,102, 8,537,105, 8,558,783 , 8,558,785, 8,558,786, 8,558,855, 8,576,164, 8,576,259, 8,593,396, No. 8,605,032, 8,643,595, 8,665,206, 8,681,191, 8,730,153, 8,810,525, 8, 928,562, 8,928,641, 8,976,444, 9,013,394, 9,019,197, 9,019,198, 9,019, No. 318, No. 9,082,352, No. 9, 171,508, 9,218,773, 9,224,338, 9,224,342, 9,224,344, 9,230,492, 9,251 736, 9,262,973, 9,269,311, 9,299,294, 9,373,289, 9,390,066, 9,390,661 , And 9,421,314, and US Patent Application Publication Nos. 2003/0102858, 2004/0246562, 2005/0253777, 2007/0070032, 2007/0076289, 2007/0091418. , 2007/0103427, 2007/01/76912, 2007/0296452, 2008/0024429, 2008/0024482, 2008/0136774, 2008/0169821, 2008/0218471, No. 2008/0291129, 2008/033780, 2009/0174651, 2009/0195568, 2009/0322721, 2010/0194733, 2010/0194789, 2010/02201012, 2010/ No. 0265561, No. 2010/0283804, No. 2011/0063314, No. 2011/0175875, No. 2011/0193840, No. 2011/0193841, No. 2011/0199671, No. 2011/0221740, No. 2012/0001957 , 2012/0987740, 2013/0063333, 2013/0194250, 2013/0249782, 2013/0321278, 2014/0009817, 2014/0085355, 2014/2004012, No. 2014/0218277, 2014/0240210, 2014/0240373, 2014/0253425, 2014/0292330, 2014/0293398, 2014/0333685, 2014/0340734, 2015/ No. 0070744, No. 2015/097877, No. 2015/010283, No. 2015/0213749, No. 2015/0213765, No. 2015/0221257, No. 2015/0262255, No. 2016/0071 See 465, 2016/0078820, 2016/093253, 2016/010910, and 2016/018777).

In many of the aforementioned patents and applications, the walls surrounding the separate microcapsules within the encapsulated electrophoresis medium can be replaced with continuous phases, thus producing so-called polymer-dispersed electrophoresis displays and electrophoresis. The medium consists of multiple separate droplets of the electrophoretic fluid and a continuous phase of the polymeric material, with separate droplets of the electrophoretic fluid in such a polymeric dispersed electrophoretic display, with separate capsule membranes. Recognize that it can be considered a capsule or microcapsule even if it is not associated with each individual droplet. See, for example, US Publication No. 2002/0131147. Therefore, for the purposes of the present application, such polymer-dispersed electrophoresis media are considered variants of the encapsulated electrophoresis medium.

A related type of electrophoresis display is the so-called "microcell electrophoresis display". In a microcell electrophoresis display, charged particles and suspended fluids are not encapsulated in microcapsules, but instead are retained in a carrier medium, eg, a plurality of cavities formed within a polymer film. For example, both are from Shipix Imaging, Inc. See International Application Publication No. WO 02/01281 and Published US Application No. 2002/0075556 assigned to.

Many of the aforementioned E Ink and MIT patents and applications also envision microcell electrophoresis displays and polymer dispersion electrophoresis displays. The term "encapsulated electrophoresis display" can refer to any such display type, which can be collectively described as "microcavity electrophoresis display" for generalization across wall morphology.

Another type of electro-optical display was developed by Philips, Hayes, R. et al. A. , Et al. It is an electrowetting display described in "Video-Speed Electronic Paper Based on Electrowetting", Nature, 425,383-385 (2003). A co-pending application No. 10 / 711,802, filed October 6, 2004, shows that such electrowetting displays can be bistable.

Other types of electro-optical materials may also be used. Of particular note is a bistable ferroelectric liquid crystal display (FLC), which is known in the art and exhibits residual voltage behavior.

The electrophoresis medium is opaque (eg, in many electrophoresis media, because the particles substantially block the transmission of visible light through the display) and can operate in reflection mode, but some electrophoresis. The display can be configured to operate in a so-called "shutter mode" in which some display state is substantially opaque and some display state is light transmissive. For example, U.S. Pat. Nos. 6,130,774 and 6,172,798, and U.S. Pat. Nos. 5,872,552, 6,144,361, 6,271,823, 6, See Nos. 225,971 and 6,184,856. Dielectrophoretic displays, which are similar to electrophoretic displays but rely on fluctuations in electric field strength, can operate in similar modes. See U.S. Pat. No. 4,418,346. Other types of electro-optical displays may also be able to operate in shutter mode.

A high resolution display may include individual pixels that can be addressed without interference from adjacent pixels. One way to obtain such pixels is to provide an array of non-linear elements such as transistors or diodes, with at least one non-linear element associated with each pixel to produce an "active matrix" display. The address or pixel electrode that addresses one pixel is connected to the appropriate voltage source through the associated non-linear element. When the non-linear element is a transistor, the pixel electrode can be connected to the drain of the transistor, and this arrangement is essentially arbitrary, as would be assumed in the discussion below, and the pixel electrode is a transistor. Can also be connected to the source of. In a high resolution array, the pixels can be arranged in a two-dimensional array of rows and columns such that any particular pixel is uniquely defined by the intersection of one defined row and one defined column. .. The source of all transistors in each column can be connected to a single column electrode, while the gates of all transistors in each row can be connected to a single row electrode. Again, the allocation of sources to rows and gates to columns can be reversed, if desired.

The display can be written in a line-by-line format. The row electrodes are connected to the row driver, which applies a voltage to the selected row electrodes to ensure that all transistors in the selected row are conductive, while these are selected. A voltage may be applied to all other rows to ensure that all transistors in no row remain non-conducting. The column electrodes are connected to the column drivers, which apply a voltage selected to drive the pixels in the selected row to their desired optical state to the various column electrodes. (The voltage described above is for a common front electrode that is provided opposite to the non-linear array of electro-optic media and can extend throughout the display. As is known in the art, the voltage is relative and 2 A measure of the charge difference between one point. One voltage value is for another voltage value. For example, a zero voltage (“0V”) has a no-voltage difference for another voltage. After a preselected interval known as "line address time", the selected row is deselected, another row is selected, and the voltage on the column driver is written by the next line on the display. Can be changed to be.

However, in use, some waveforms can generate a residual voltage to the pixels of the electro-optical display, and as is clear from the discussion above, this residual voltage produces some unwanted optical effects and is generally , Not desirable.

As raised herein, the "shift" in the optical state associated with an address pulse is that the first application of a particular address pulse to an electro-optical display is the first optical state (eg, a first gray). It refers to a situation in which subsequent application of the same address pulse to an electro-optical display results in a second optical state (eg, a second gray tone). The residual voltage can cause a shift in the optical state because the voltage applied to the pixels of the electro-optical display during the application of the address pulse includes the sum of the residual voltage and the voltage of the address pulse.

"Drift" in the optical state of the display over time refers to a situation in which the optical state of the electro-optical display changes while the display is stationary (eg, during a period when no address pulse is applied to the display). The residual voltage can cause drift in the optical state because the optical state of the pixel can depend on the residual voltage of the pixel and the residual voltage of the pixel can decay over time.

As discussed above, "afterglow" refers to a situation in which the traces of the previous image are still visible after the electro-optical display has been rewritten. The residual voltage can give rise to "edge afterglow", a type of afterglow in which some contours (edges) of the previous image remain visible.

(Exemplary EPD)

FIG. 1 shows a schematic representation of pixels 100 of an electro-optical display according to the subject matter presented herein. Pixel 100 may include imaging film 110. In some embodiments, the imaging film 110 can be bistable. In some embodiments, the imaging film 110 may include, for example, an encapsulated electrophoretic imaging film that may include charged pigment particles.

The imaging film 110 may be arranged between the front electrode 102 and the back electrode 104. The front electrode 102 may be formed between the imaging film and the front of the display. In some embodiments, the front electrode 102 may be transparent. In some embodiments, the front electrode 102 can be formed from any suitable transparent material, including, but not limited to, indium tin oxide (ITO). The back electrode 104 may be formed on the opposite side of the front electrode 102. In some embodiments, a parasitic capacitance (not shown) can be formed between the front electrode 102 and the back electrode 104.

Pixel 100 can be one of a plurality of pixels. Multiple pixels can be arranged in a two-dimensional array of rows and columns to form a matrix, and any particular pixel is uniquely defined by the intersection of one defined row and one defined column. To. In some embodiments, the pixel matrix can be an "active matrix" in which each pixel is associated with at least one nonlinear circuit element 120. The non-linear circuit element 120 may be coupled between the back plate electrode 104 and the address electrode 108. In some embodiments, the non-linear element 120 may include a diode and / or a transistor including, but not limited to, a MOSFET. The drain (or source) of the MOSFET can be coupled to the back plate electrode 104, the source (or drain) of the MOSFET can be coupled to the address electrode 108, and the gate of the MOSFET controls the activation and deactivation of the MOSFET. It can be coupled to a driver electrode 106 configured to do so. (For simplicity, the MOSFET terminals coupled to the backplate electrode 104 will be referred to as the MOSFET drain, and the MOSFET terminals coupled to the address electrode 108 will be referred to as the MOSFET source. However, those skilled in the art will recognize that in some embodiments, the source and drain of the MOSFET can be interchanged.)

In some embodiments of the active matrix, the address electrodes 108 of all pixels in each column may be connected to the same column electrode, and the driver electrodes 106 of all pixels in each row may be connected to the same row electrode. .. The row electrode can be connected to the row driver, which applies a voltage to the selected row electrode sufficient to activate the non-linear elements 120 of all pixels 100 in the selected row. You can select one or more rows of pixels. The row electrode may be connected to a row driver, which may apply a voltage suitable to the address electrode 106 of the selected (activated) pixel to drive the pixel to the desired optical state. The voltage applied to the address electrode 108 can be relative to the voltage applied to the pixel front plate electrode 102 (eg, a voltage of about zero volts). In some embodiments, the front plate electrodes 102 of all pixels in the active matrix can be coupled to a common electrode.

In some embodiments, the pixels 100 of the active matrix can be written in a row-by-line format. For example, a row of pixels can be selected by the row driver, and a voltage corresponding to the desired optical state for the row of pixels can be applied to the pixel by the column driver. After a preselected interval known as "line address time", the selected row can be deselected, another row can be selected, and the voltage on the column driver is written by another line on the display. Can be changed so that it can be changed.

FIG. 2 shows a circuit model of an electro-optical imaging layer 110 arranged between a front electrode 102 and a back electrode 104 according to the subject matter presented herein. The resistor 202 and the capacitor 204 may represent the resistance and capacitance of the electro-optic imaging layer 110 including any adhesive layer, the front electrode 102, and the back electrode 104. The resistor 212 and the capacitor 214 may represent the resistance and capacitance of the lamination adhesive layer. The capacitor 216 is an interfacial contact between the front electrode 102 and the back electrode 104, for example, between the imaging layer and the lamination adhesive layer and / or the interface between the lamination adhesive layer and the backplane electrode. It can represent the capacitance that can be formed in the area. The voltage Vi across the pixel imaging film 110 may include the residual voltage of the pixel.

Detecting, reducing, or eliminating edge artifacts and afterglows in the electro-optical display described above is likely to require additional image data processing, Amundson et al. U.S. Patent Application No. 2013/0194250A1 (“Amundson”) and Sim et al. The detection and erasure methods described in U.S. Patent Application 2016/0225322A1 (“Sim”), all of which are incorporated herein in their entirety, are applicable to several image data processing methods. Is. However, such image data processing methods (also erasing edge artifacts and pixel afterglow) may require their own processing time, which may not always be available. Therefore, it may be desirable to perform image data processing at the same time as the image data update process in a fast paced update waveform mode such as the direct update waveform mode described below. In addition, edge artifacts and pixel afterglow elimination can only be triggered and performed when desired.

(Direct update or DUDS)

In some applications, the display may utilize a fast paced update waveform mode, such as a "direct update" waveform mode ("DUDS"). DUDS can have more than one gray level, typically less gray level than the grayscale drive scheme (“GSDS”), although GSDS can achieve transitions between all possible gray levels. The most important characteristic of DUDS is the "indirect" transition often used in GSDS (at least in some transitions, the pixel goes from the initial gray level to one extreme optical state and then in the opposite direction to the final gray. Driven to level: In some cases, the transition is driven from the initial gray level to one extreme optical state, from there to the opposite extreme optical state, and finally to the final extreme optical state. In contrast to (which can be achieved by), the transition is handled by a simple one-way drive from the initial gray level to the final gray level. See, for example, the drive scheme illustrated in FIGS. 11A and 11B of US Pat. No. 7,012,600 described above. Therefore, this electrophoretic display has a saturation pulse length (“saturation pulse length” at a particular voltage that is sufficient to drive the display's pixels from one extreme optical state to the other optical state. The DUDS can have an update time in grayscale mode of about 2-3 times (defined as a period), or about 700-900 ms, while the DUDS is equal to or about 200-200 to the length of the saturation pulse. It has a maximum update time of 300 milliseconds.

It should be understood that the direct update (DU) waveform mode or drive scheme described above is used herein to illustrate the general operating principles of the subject matter disclosed herein. It is not intended to serve as a limitation to the subject. These operating principles can be easily applied to other waveform modes or schemes.

The DU waveform mode is a drive scheme that normally considers updates to white and black with empty self-transition. DU mode has a short update time to quickly present black and white, with a minimal appearance of "flash-like" transitions, and the display appears to be blinking, partly. It may not be visually appealing to the eyes of the viewer. DU mode can sometimes be used to present menus, progress bars, keyboards, etc. on the display screen. Edge artifacts can occur on black and white backgrounds because both white-white and black-black transitions are null (ie, undriven) in DU mode.

As explained above, when an undriven pixel is located adjacent to an updated pixel, the driving of the driven pixel is optical over an area slightly larger than the area of the driven pixel. A phenomenon known as "blooming" occurs in which this area penetrates into an area of adjacent pixels. Such blooming manifests itself as an edge effect along the edges where the undriven pixels are located adjacent to the driven pixels. Similar edge effects occur in the case of area updates, except that they occur at the boundaries of the area where the edge effect is being updated (only certain areas of the display are updated to show, for example, an image). Happens when using. Over time, such edge effects become visually distracting and must be eliminated. So far, such edge effects (and the effects of color drift on undriven white pixels) have typically been eliminated by using a single global erase or GC update at intervals. It was. Unfortunately, the use of such occasional GC updates can reintroduce the problem of "flash-like" updates, and in fact, the flashiness of updates occurs at long intervals of flash-like updates. Can be enhanced by the fact that it is nothing more than.
(Simultaneous image update and edge artifact data processing)

By comparison, some of the display pixel edge artifact reduction methods can result in additional latency due to image processing designed to detect and eliminate edge artifacts after each image update. In addition, the use of DC non-equilibrium waveforms in these reduction methods does not allow a small dwell time between updates (such as the DU mode raised above) to allow sufficient time to perform post-drive discharge. So it wouldn't be feasible. And in the absence of post-drive discharge, there is a potential risk to overall optical performance and module reliability.

Alternatively, in some embodiments, image data processing, such as those described in Amundson and Sim, can be invoked at the same time as the image update process. For example, when the display 100 is updating the first image, the image data of the first and subsequent second images are processed to identify pixels that can cause edge artifacts or other unwanted optical defects. Can be done. Subsequently, such data may be stored in buffer memory for an edge artifact erasing process that should be performed at a later time. In some embodiments, this data processing of the image can occur when subsequent images are being fed to the EPDC. In some other embodiments where the image to be updated is known to the display, this data process of the image can occur before subsequent images are updated.

As the electro-optical display undergoes optical changes, one way to track, generate, and store this edge artifact information is to generate a map, which will give rise to edge artifacts. It may contain information such as pixels in a likely display. One such method is Sim et al. U.S. Patent Application No. US2016 / 128,996 (incorporated herein as a whole).

For example, in some embodiments, pixel edge artifacts generated under a drive scheme or waveform mode may be stored in memory (eg, a binary map), for example, each display pixel may have an indicator MAP (i). Pixels that can be represented by, j) and can give rise to edge artifacts can be flagged, and their map information (ie, MAP (i, j) directives) can be stored in the binary map. One approach that can be used to track generated edge artifacts on a map and flag such pixels is illustrated below.
MAP (i, j) = 0 for All i, j
For All DU updates in continuous order For All pixels in any order (i, j):
If pixel gray tone transition is white → white, AND all four basic adjacent pixels have the next gray tone of white, and AND at least one basic adjacent pixel has the current non-white gray tone. When all the adjacent pixels of AND MAP (i, j) are 0, then MAP (i, j) = 1.
Else, if pixel gray tone transition is black → black, AND at least one basic adjacent pixel has the current gray tone AND the next gray tone of black, and all AND MAPs (i, j) When the adjacent pixel is 0, then MAP (i, j) = 2.
End
End
End

In this approach, when certain conditions are met, a display pixel designated as MAP (i, j) can be flagged with a number of 1, indicating that dark edge artifacts have formed at this pixel. Some of the required conditions may include: (1) this display pixel is undergoing a white-white transition, (2) all four basic adjacent pixels (ie, the four closest). The adjacent pixel) has the next gray tone of white, (3) at least one basic adjacent pixel has the current non-white gray tone, (4) the adjacent pixel (ie, the four basic adjacent pixels, and , Neither diagonally adjacent pixels) are currently flagged for edge artifacts.

Similarly, when certain conditions are met, the display pixel MAP (i, j) can be flagged with a number of 2 indicating that a white edge has been formed on this pixel. Some of the required conditions may include: (1) this pixel is undergoing a black-black transition, (2) at least one basic adjacent pixel is the current gray tone that is not black. And the next gray tone is black, (3) any of the adjacent pixels (ie, the four basic adjacent pixels, and also the diagonal adjacent pixels) are currently flagged for edge artifacts. Not attached.

When used, one advantage of this approach is that the above image processing (ie, map generation and pixel flagging) occurs at the same time as the display image update cycle, so that the generated map is only at the end of the update cycle. It is possible to avoid creating extra latency to the update cycle, at least in part because it is required.

When the update mode is complete (eg, the display stops using a particular update mode), the pixel information accumulated by the generated map is subsequently edged (eg, using the output waveform mode). Can be used to erase artifacts. For example, pixels flagged for edge artifacts can be erased using a low flash waveform with a specialized waveform.

In some embodiments, completely erased white-white and black-black waveforms can be used to eliminate edge artifacts, along with special edge-erased white-white and black-black waveforms. For example, the equilibrium pulse pair described in US Patent Application 2013/0194250, which is incorporated herein as a whole, describes:
For All pixels in any order (i, j)
If the If pixel gray tone transition is not white → white and not black → black, Else, if MAP (i, j) that calls the normal DU_OUT transition is 1, and the pixel gray tone transition is white → white. Else, if pixel xel gray tone transition to apply a special perfect white / white waveform is white → white and AND has a special edge if it has a MAP (i, j) where at least one basic adjacent pixel is 1. Else, if MAP (i, j) == 2 to apply an erasing white / white waveform, and when the pixel gray tone transition is from black to black, apply a special completely black / black waveform Else, if pixel xel If the gray tone transition is black → black and AND has a MAP (i, j) where at least one basic adjacent pixel is 2, then apply a special edge-erased black / black waveform Black → black in the Otherwise DU_OUT waveform table. / White → Call the white transition End
End

In this approach, a DU_OUT transition scheme (eg, a modified DU scheme that includes an edge artifact reduction algorithm) can be applied to pixels that do not undergo a white-white or black-black transition, eg, these pixels , Can undergo normal transition updates as if under a normal DU drive scheme. Instead, a special fully white-white waveform may be applied for pixels undergoing a white-white transition with dark edge artifacts (ie, MAP (i, j) = 1). In some embodiments, the white-white waveform can be a waveform similar to that illustrated in FIG. 3c, which can be substantially DC equilibrium, where DC equilibrium is a voltage bias as a function of scale and time. This means that the sum of the applications is virtually zero overall; otherwise, the pixels will undergo a white-white transition and at least one basic adjacent pixel will have a dark edge artifact (ie, MAP (ie, MAP)). If i, j) = 1), a special edge-erasing white-white waveform is applied (eg, FIG. 3a); still, the pixels are still white edge artifacts (ie, MAP (i, j) = If it has 2) and is undergoing a black-black transition, a special completely black-black waveform as shown in FIG. 4b can be applied; still, the pixels undergo a black-black transition. And if at least one basic adjacent pixel is flagged for a white edge artifact (ie, MAP (i, j) = 2), then a special edge-erased black color, as illustrated in FIG. 4a. Apply a black waveform; otherwise, use the waveform from the DU-OUT waveform table to apply a black / black or white / white transition waveform to all other pixels.

Using the method described above, a completely erased white / white and black / black waveform is used in conjunction with a completely erased white / white and black / black waveform to eliminate edge artifacts. In some embodiments, special edge-erased white-white waveforms are available from Amundson et al. A pulse pair as described in US Patent Publication No. 2013/0194250 (incorporated herein as a whole), or a DC non-equilibrium pulse drive to white as illustrated in FIG. 3b. It can take the form, in which case the post-drive discharge described can be used to discharge the residual voltage and reduce device stress. Similarly, a DC non-equilibrium pulse as shown in FIG. 4a can be used to drive the pixels black, in which case post-drive discharge can be performed again. As illustrated in FIG. 4, such DC non-equilibrium pulses have only a positive 15 volt drive over a period of time. In this configuration, excellent edge erasure performance can be achieved at the expense of slight transition appearance defects (eg, flashes) due to the use of special data erasure waveforms.

In another embodiment, transition appearance defects (eg, flashes) can be reduced using alternative implementations described below.
For All pixels in any order (i, j)
If the If pixel gray tone transition is not white → white and not black → black, Else, if MAP (i, j) that calls the normal DU_OUT transition is 1, and the pixel gray tone transition is white → white. , Apply a DC unbalanced drive pulse to white Else, if MAP (i, j) == 2, and when the pixel gray tone transition is from black to black, apply a DC unbalanced drive pulse to black. End to call the black → black / white → white transition of the Otherwise DU_OUT waveform table
End

In this approach, instead of using the specialized edge-erasing waveform as described in the first method above, a DC non-equilibrium waveform can be used to eliminate edge artifacts. In some cases, post-drive discharge can be used to reduce hardware stress due to non-equilibrium waveforms. In use, when the display pixel does not undergo any of the white / white or black / black transitions, the normal DU-OUT transition is applied to the pixel. Otherwise, if the display pixel is identified as having a dark edge artifact (ie, MAP (i, j) = 1) and is undergoing a white-white transition, a DC unbalanced drive pulse will make the pixel white. Used to drive (eg, pulses similar to those illustrated in FIG. 3b); otherwise, the display pixel is identified as having a white edge artifact (ie, MAP (i, j) = 2). And if it is undergoing a black-black transition, a DC non-equilibrium drive pulse (eg, a pulse similar to that shown in FIG. 4a) is applied to drive the pixel black; otherwise. Call the black / black or white / white transition of the DU-OUT waveform table to the display pixel.

In yet another embodiment, instead of storing edge artifact information in a designated memory location, in the image buffer associated with the controller unit of the display (eg, using the following image buffer associated with the controller unit). Edge artifact information can be advanced.
For All DU updates in continuous order For All pixels in any order (i, j):
If the If pixel gray tone transition is white → white, AND all four basic adjacent pixels have the next gray tone of white, and AND at least one basic adjacent pixel has the current non-white gray tone. the next gray tone is set to a special white / white image state.
Else, if Pixel gray tone transition is black → black and AND at least one basic adjacent pixel is not black Current gray tone AND If the next gray tone of black has the next gray tone, then the next gray tone is a special black Set to black-white image state.
End
End
End

In this approach, for a pixel undergoing a white-white transition, and for all four basic adjacent pixels having the next gray tone of white, if at least one of the current gray tones of the basic adjacent pixel is not white. Set the next gray tone of the pixel to a special white / white image state in the next image buffer; otherwise, the gray tone transition of the pixel is black / black and at least one basic adjacent pixel is black. If you have a current gray tone that is not and a next gray tone that is black, the next gray tone of the pixel is set to a special black / black image state in the next image buffer. In use, during the update cycle, the special white-white and special black-black image states can be the same as the white-white and black-black image states for both application of waveform transitions and image processing. With respect to the application of waveform transitions, it means:
-Special white state-> white state (ie, white state to white state) is equivalent to white state-> white state (ie, white state to white state) of the waveform look-up table.-Special white state-> arbitrary The gray state (that is, from the white state to any gray state) is equivalent to the white state of the waveform look-up table etc. → any gray state (that is, from the white state to any gray state) ・ Special black state → black The state (ie, black state to black state) is equivalent to the black state → black state (ie, black state to black state) of the waveform look-up table. ・ Special black state → any gray state (ie, black state). (To any gray state) is equivalent to any gray state (that is, from black state to any gray state) from the black state of the waveform look-up table, etc. During the output mode, the special white / white state changes to white. Received a DC unbalanced pulse in (eg, FIG. 3b illustrates an exemplary such pulse), and a special black / black state received a DC unbalanced pulse to black (eg, FIG. 4a). Illustrates an exemplary such pulse). The imaging algorithm processing occurs in the background during the DU mode update, meaning that the DU update time can be used to process the image.

5a and 5b illustrate displays with and without applied edge artifact reduction. In practice, when edge artifact reduction is not applied, white edges on a black background are clearly visible, as shown in FIG. 5a. In contrast, FIG. 5b shows that white edges are erased using one of the proposed methods proposed herein.

In some embodiments, pixels with or potentially producing edge artifacts are flagged as described above and have a different memory than the memory buffer used for image updates. Can be remembered in place. For example, in memory that is physically separate from the buffer memory used for image updates. However, in some cases it may be desirable to reduce the amount of memory used. Therefore, in some embodiments, the memory used for image updates (eg, image update buffer memory) can also be used to store cumulative edge artifact information. For example, while an electro-optical display is undergoing an optical change (eg, image update), instead of generating a map with all the pixels, whether each pixel has an edge artifact for a particular pixel. Can be associated with an indicator designed to indicate. This indicator can be used to indicate whether a particular pixel can be flagged for edge artifacts. As the display undergoes more image updates (eg, more optical changes), perhaps more pixels will have edge artifacts (eg, flagged or turned on). Can be flagged with respect to the edge artifact indicator associated with. At a later time, these pixel flags flagged for edge artifacts can all be erased or reset in unison by the reset waveform.

(Erase edge artifacts)

The processed edge artifact data can be used at a convenient time to erase the edge artifacts. The erasing process can be triggered or initiated under a variety of conditions.

In some embodiments, the erase request may be initiated by the host (eg, processor) as well as other requests sent by the host to the EPDC, such request being sent at the same time as other image update requests. Can be done. For example, in order to clear the accumulated edge artifacts caused by the DUDS waveform mode, following the bidirectional dialog in which the DUDS waveform mode was used to update the display, the host specifically for clearing the edge artifacts. You may require the EPDC to set a time frame.

In some other embodiments, the erasing process can be initiated when it is convenient for display. For example, when the EPDC has been idle for a certain amount of time, the EPDC may choose to start the elimination process and use the cumulative edge artifact data to erase the edge artifacts.

In yet another embodiment, this processed image data, including pixel identification data with edge artifacts, can be used by a drive scheme or update waveform mode that includes a waveform to eliminate the edge artifacts. For example, in applications where the DUDS waveform mode uses a pen input that is used for its fast response time, subsequent waveform modes used for antialiasing may include edge artifact elimination waveforms that follow. In the waveform mode, the processed image data accompanied by the edge artifact information can be used to erase the edge artifact.

In some embodiments, the Global Edge Elimination (GEC) waveform mode can be used to eliminate edge artifacts. FIG. 6 illustrates sample GEC waveforms, which include top-off pulses configured to drive display pixels into extreme optical states. Such a waveform can consist of 6 frames or a duration of 66 ms at a temperature of 25 degrees Celsius. The GEC can have a shorter duration as compared to a waveform mode with a built-in edge eraser. In this mode, GEC can be conveniently employed to eliminate edges in relation to various existing drive waveform modes without introducing excessive latency. For example, when GEC is used with the DUDS waveform mode described above, GEC occupies only a short duration, so post-drive discharge follows GEC before subsequent images are updated on the display. Can be carried out. In some embodiments, the EPDC may select and select the waveform to be used, depending on the amount of edge artifacts present. For example, if the amount of edge artifacts exceeds a threshold, EPDC may select a global erase waveform (mode) to erase the entire display.

In another embodiment, the EPDC may initiate an erasure waveform if there are too many pixels with edge artifacts. For example, EPDC may have an algorithm configured to track the total number of pixels with edge artifacts and compare them to the total number of pixels on the display. Such comparisons can be stored as percentile values in buffer memory. Such stored values may be periodically compared to a predetermined threshold, and if this stored value exceeds the threshold, EPDC may choose to initiate global erasure waveform mode. The global erase waveform can reset all pixels on the display (eg, drive all pixels to extreme gray tone levels or color states).

It will be apparent to those skilled in the art that numerous modifications and modifications can be made to the specific embodiments of the invention described above without departing from the scope of the invention. Therefore, the entire above description should be construed in an exemplary, non-limiting sense.

Claims (8)

A method of driving an electro-optical display having a plurality of display pixels, wherein the electro-optical display is controlled by a display controller, and the display controller is associated with a host for providing operation commands to the display controller. The above method is
Updating the display with the first image,
Updating the display with a second image following the first image,
To process the first image and the image data associated with the second image, identify display pixels with edge artifacts, and generate image data associated with the identified pixels.
To store the image data related pixels with edge artifacts in a memory location,
A method comprising initiating a waveform to eliminate said edge artifacts. The method of claim 1, wherein generating image data associated with the identified pixel comprises flagging the identified pixel with an indicator. The method of claim 2, wherein the step of identifying a display pixel with an edge artifact comprises determining a display pixel having a gray tone different from at least one of its basic adjacent pixels. The method of claim 2, wherein the step of identifying a display pixel with an edge artifact comprises flagging the identified pixel in buffer memory associated with the controller of the display. The method of claim 1, wherein the step of initiating a series of waveforms comprises receiving an erase command from the host. The method of claim 1, wherein the step of initiating a series of waveforms comprises initiating an erased waveform after the display controller has been idling for a predetermined duration. The method of claim 1, wherein the step of initiating a series of waveforms comprises applying a waveform mode having a waveform for eliminating edge artifacts. The method of claim 1, wherein the step of initiating a series of waveforms comprises applying a DC non-equilibrium waveform.

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