Method for fast and smart advanced color electrophoretic switching using a multi-level source mode

Abstract

The invention discloses a method for fast and smart ACeP switching of a 3- or 4-pigment medium in an electrophoretic display system by an electronic circuitry designed for driving an only 2-pigment medium, whereas the electronic circuitry comprises a controller configured to control a multi-level source driver IC which is connected to switching transistors of pixels of the display system. The objective to provide a method and an apparatus to drive 3- and 4-pigment media with a simple and less complex electronic architecture and especially without the additional need of several ACVcom sources, is solved by using a multi-level source mode of the multi-level source driver IC, filling a pre-image buffer of the IC with a target image of the display system, whereas every single pixel is represented by two pixels in the pre-image buffer, filling a post-image buffer of the IC alternating with 0 and 1, defining voltage level sequences depending on post and pre color levels of displayed images on the display system and storing them in a look-up table of the electronic circuitry, wherein a single pixel of the display system is addressed with a 4-bit wide data word by the multi-level source driver IC, whereas the 4-bits are concatenated by 2-bits of the pre-image buffer and 2-bits of the post-image buffer to address different source voltages so that each single pixel of the display system can be supplied by at least five different source voltages.

Description

[0001] The invention relates to a method for fast and smart advanced color electrophoretic (ACeP) switching of a 3- or 4-pigment medium in an electrophoretic display system by an electronic circuitry designed for driving an only 2-pigment medium, whereas the display system comprises a transparent top electrode, a bottom electrode and the 3- or 4-pigment medium between the top and bottom electrode, whereas the electronic circuitry comprises a memory configured to store images, a controller configured to control a multi-level source driver integrated circuit (IC) which is connected to switching transistors of pixels of the display system.

[0002] The invention relates also to an apparatus configured to perform the method.

[0003] An electrophoretic display system, commonly known as an e-paper display, is a type of electronic paper technology used to create low-power, reflective displays that mimic the appearance of ink on paper. These displays are commonly found in e-readers, electronic shelf labels, and other applications where high contrast, wide viewing angles, and low power consumption are desired.

[0004] The core component of an electrophoretic display is microcapsules or microspheres. These microcapsules contain charged pigments or nanoparticles suspended in a clear fluid. The terms pigments or nanoparticles are used synonymously. The nanoparticles and the fluid are also called an electrophoretic medium. The nanoparticles have different charges, positively and negatively charged, and are typically black and white. There are also grayscale and even color e-paper displays. The display is constructed by sandwiching the microcapsule-containing fluid between two electrodes on a substrate. One of the electrodes, often the top- or front electrode is usually transparent typically made of ITO (Indium tin oxide) (Fig. 1).

[0005] A matrix of thin-film transistors (TFT) or other addressing circuitry is present on the substrate. This circuitry allows individual pixels / microcapsules to be selectively charged, controlling the movement of pigments.

[0006] When a voltage is applied between the transparent top electrode and a backplane as a counterpart electrode, an electric field is generated across the microcapsules. Depending on the polarity of the applied voltage, the charged nanoparticles or pigments within the microcapsules migrate towards one of the electrodes (Fig. 2). For instance, if a positive voltage is applied to the pixel electrode, positively charged black pigments move upward, causing that area of the display to appear black. Conversely, if a negative voltage is applied, negatively charged white pigments move upward, resulting in a white appearance. To change the gray level of a pixel, several pulses driving the pixel to white (-15V) or black (+15V) are needed. In grayscale displays, the sequence of voltage pulses applied to each pixel is varied in order to achieve different shades of gray. Color electrophoretic displays work similarly but use additional pigments or nanoparticles and much more complex addressing methods to achieve a wider color gamut.

[0007] The color electrophoretic display system uses a subtractive color scheme, which refers to the color mixing process that result from the absorption of light. It is based on the colors Cyan, Magenta, and Yellow (CMY). In this color scheme, colors are created by subtracting color components through absorption rather than adding light (Fig. 3). In the description of the invention the names of the colors are used, and in the figures the different colors are presented by different hachures. The subtractive color mixing works as follows: Cyan absorbs red and reflects blue and green. Magenta absorbs green and reflects red and blue. Yellow absorbs blue and reflects red and green. When these colors are combined, each color absorbs certain wavelengths of light, resulting in less light being reflected and creating a mixed color. For instance, combining cyan and magenta will result in a dark shade of blue since cyan absorbs red light and magenta absorbs green light. The subtractive color scheme is commonly used in printers, painting, and other applications where colors are generated by mixing pigments. Therefore, in the present electrophoretic medium, the colored pigments cyan, magenta and yellow are filter particles / pigments and the white and black particles are opaque.

[0008] Electrophoretic displays are reflective displays, meaning they rely on external light sources for visibility, just like traditional paper. Ambient light, such as sunlight or indoor lighting, is used to illuminate the display. This makes electrophoretic displays highly readable in various lighting conditions, including bright sunlight.

[0009] One of the major advantages of electrophoretic displays is their extremely low power consumption. Power is only required when changing the content of the display, and once an image is set no power is needed to maintain it. This property makes e-paper ideal for applications where battery life is crucial. Electrophoretic displays are bi-stable, meaning they can hold an image without continuous power. This is because the charged pigments remain in place until a voltage is applied to change their position. This bi-stable nature contributes to the low power consumption of these displays.

[0010] These displays are well-suited for applications requiring high contrast, wide viewing angles, and minimal power usage.

[0011] As mentioned above, an electrophoretic medium consists of colored, charged nanoparticles, which can be moved by applying an electrical field to them. Two-pigment systems consist of two nanoparticles types, e. g. black and white, which are charged with inverse polarity and can be driven by applying two voltage levels of the same value but different pre-signage to the electrodes.

[0012] As a result, todays electronics architectures for two-pigment media are based on a three level voltage drive scheme: A positive source voltage (e. g. +15V / black), a negative source voltage (e. g. -15V / white) and zero volt (0V / no change) for pixels where the medium remains unchanged. If a positive source voltage of +15V is applied to the back-electrode the positively charged black nanoparticles move upwards to the transparent top electrode and the display appears black at this position. If a negative source voltage of -15V is applied to the back-electrode the negatively charged white nanoparticles move upwards to the transparent top electrode and the display appears white at this position. If a voltage difference between the back- and front-electrode is 0V the nanoparticles do not move and remain unchanged.

[0013] Three- and four level systems consist of three or four colored nanoparticle types, which are charged with positive or negative polarity of different values. These systems use so-called 3- or 4-pigment media. They are addressed by applying a sequence of varying voltage levels with varying polarity.

[0014] Four-pigment systems consist of four colored nanoparticle types, which are charged with positive or negative polarity of different values. Two of them needs only a low positive / negative electrical field (e. g. + / - 15V) to be moveable and moving slow. The other two need a high electrical field (e. g. + / - 30V) to be moveable but moving faster.

[0015] Today electronics for 4-pigment systems using still the 2-pigment system approach. The same level of source voltage (e. g. + / - 15V) is supplied. Since that is only sufficient for the low charged particles, and to move the high charged particles, an additional ACVcom voltage has to be applied on the opposite side of the media. The level of the ACVcom voltage is nearly in the same range of source voltage (e. g. + / - 15V). The combination of different source and ACVcom voltages allows reaching the full spectrum from negative to positive high voltage (e. g. + / -30V) (Fig. 4). Fig. 4 shows the voltage over the media depending on the ACVcom voltage and the source voltage.

[0016] The negative aspects of said described current approach are that the control of the ACVcom needs additional hardware and logic to control it. This results in an enhanced footprint of the circuity. Furthermore, only a subset of voltage levels is available at the same time (e. g. {-30V, - 15V, 0V} or {-15V, 0V, +15V} or {0V, +15V, +30V}). This means that the overall image update has to be split in several phases. That causes that while some image parts are actively switched others are passive and non-switching. That results in a negative optical behavior, such as a long duration of the overall image update, image flickering and optical drifting of passive and non-switching areas caused by parasitic electrical charges.

[0017] For some application this negative aspects will not be critical, e. g. shelf label and image frames.

[0018] However, there are lots of critical applications, while it will be used as information screen with fast or continuously changing content, like an e-Reader or a Tabled Computer it does. Since the image / content update is in the focus of an observer, image update duration, flickering and drift effects will be very disruptive perceived.

[0019] It is therefore an objective of the present invention to provide a method that can drive 3- and 4-pigment media in electrophoretic display systems with a simple and less complex electronic architecture previously designed for controlling 2-pigment media and especially without the additional need of several ACVcom sources. In addition, the method should enable any image updates, e. g. text, pictures, graphics etc., on an electrophoretic media with a four-pigment system to be fluid, flicker free, fast and qualitative comparable to a two-pigment system.

[0020] The objective of the present invention will be solved by a method according to independent claim 1. The method for fast and smart advanced color electrophoretic (ACeP) switching of a 3- or 4-pigment medium in an electrophoretic display system by an electronic circuitry designed for driving an only 2-pigment medium, whereas the display system comprises a transparent top electrode, a bottom electrode and the 3- or 4-pigment medium between the top and bottom electrode, whereas the electronic circuitry comprises a memory configured to store images, a controller configured to control a multi-level source driver integrated circuit (IC) which is connected to switching transistors of pixels of the display system, said method uses a multi-level source mode of the multi-level source driver IC and comprises the following steps: filling a pre-image buffer of the electronic circuitry with a target image of the display system, whereas every single pixel of the display system is represented by two pixels in the pre-image buffer of the electronic circuitry, and filling a post-image buffer of the electronic circuitry alternating with 0 and 1, and defining voltage level sequences depending on post and pre color levels of displayed images on the display system which are stored in a look-up table of the electronic circuitry, wherein a single pixel of the display system is addressed with a 4-bit wide data word by the multi-level source driver IC, whereas the 4-bits are concatenated by 2-bits of the pre-image buffer and 2-bits of the post-image buffer to address different source voltages so that each single pixel of the display system can be supplied by at least five different source voltages.

[0021] The advantage of the inventive method is that it eliminates the need of an additional ACVcom voltage regulation, since with the usage of a pre- and post-image buffer more than four different voltage levels can be addressed. Therefore, the method enables applying low and high source voltages in parallel, thus there is no need to split the overall update into several frames, it eliminates image flickering and reduces the overall image update duration. Moreover, the realization with an electronic architecture for 2-pigment systems has the advantage that the electronic architecture for 4-pigment systems are currently not available on the market, because they are not yet developed or not disclosed whereas electronic architecture for 2-pigment systems are well evaluated and available on the market.

[0022] The pre-image buffer and the post-image buffer have the same size and can be part of the memory of the electronic circuitry.

[0023] In an embodiment of the inventive method, the multi-level source driver IC is supplied by a positive high voltage P1, a positive low voltage P2, a negative high voltage N1 and a negative low voltage N2, respectively, whereas the multi-level source driver IC comprises an 8-bit wide data input bus for addressing more than four different source voltages for switching the pixels of the display system.

[0024] In a further embodiment of the inventive method, the controller controls the multi-level source driver IC, which outputs five voltage levels in parallel, especially voltage levels of -30V, -15V, 0V, +15V and +30V. Depending on the control signals of the controller, the multi-level source driver IC outputs five voltage levels in parallel to the source lines of the switching transistors of the pixels of the display system.

[0025] In another further embodiment of the inventive method, information of two pixels of the display system per clock is transmitted to the multi-level source driver IC. Registers D0...D3 control a first pixel and registers D4... D7 control a second pixel, respectively.

[0026] Since a standard electronic architecture for 2-pigment systems can only output a 2-bit wide word for each display pixel, what would only allow addressing a maximum four voltage levels, this is not sufficient to address at least five different voltage levels.

[0027] To realize the multi-source voltage supply, a multi-level source driver IC is connected to a back electrode of the display system beneath the 4-pigment media. Further, the multi-level source driver IC is supplied by positive and negative low and high voltages on N1, N2 and P1, P2. To address the different source voltages, the multi-level source driver IC has an 8-bit wide data input bus controlled by the controller. Since each pixel needs a 4-bit wide data word, e. g. D0...D3 or D4...D7, to address either 0V or positive / negative low or high voltage, the information of two pixel per clock can be transmitted to the multi-level source driver IC by the controller.

[0028] The information for updating the pixels of the display system is generated by filling the pre-image buffer with a target image, but with doubled source line size. E. g. an image with 480 source lines is stretched to a width of 960 source lines. So according to the inventive method every single pixel on the display area is represented by two pixels in the electronic memory. The post-image buffer is filled alternating with 0 and 1. According to a look-up table, which presents and defines the voltage level sequences for switching a color of one pixel to another color, depending on a post- and pre-color level of said pixel. So, in an embodiment of the present invention, post- and pre-color levels are defined as values between 0 <= n <= 15, whereas n is a natural number. Hence, a typical source and target color is defined as value in between 0 ... 15. At least for every target color two voltage level sequences have to be defined: One voltage level sequence from target color to 0 and one voltage level sequence from target color to 1.

[0029] The inventive method allows that 2-bits from the 1st pixel and 2-bits form the 2nd pixel in the controller representing the 4-bits required for the pixel on the display.

[0030] In a further embodiment of the inventive method, a length of the voltage level sequences to change a color of one pixel to another color has to be the same, whereas if a target color is reached by a shorter voltage level sequence, said voltage level sequence is filled with Null frames.

[0031] To get prioritized text drawing is mainly influenced by the voltage level sequence-design. The time span to achieve certain colors with the 4-pigment medium varies from color to color. Since the voltage level sequence-length for every color has to be the same, shorter waveforms have to be filled with Null Frames (0V). It is the decision of the voltage level sequence-designer to fill the voltage level sequence at the beginning or at the end with Null Frames.

[0032] However, to achieve fast readable text, the positive / negative high / low pulses to achieve the color black should be come prior to its Null Frames. So, in another embodiment of the inventive method, positive / negative high / low voltage pulses to achieve a black color should be come prior to its Null Frames.

[0033] The objective of the invention will also be solved by an apparatus according to independent apparatus claim 8. The inventive apparatus for fast and smart advanced color electrophoretic (ACeP) switching of a 3- or 4-pigment medium in an electrophoretic display system by an electronic circuitry designed for driving an only 2-pigment medium, whereas the display system comprises a transparent top electrode, a bottom electrode and the 3- or 4-pigment medium between the top and bottom electrode, whereas the electronic circuitry comprises a memory configured to store images, a controller configured to control a multi-level source driver integrated circuit (IC) which is connected to switching transistors of pixels of the display system, a pre-image buffer configured to buffer a target image of the display system, a post-image buffer configured to store alternating 0 and 1, and a look-up table configured to store post- and pre- color levels of displayed images on the display system, is configured to perform the method according to one of the claims 1 to 7.

[0034] The prioritized text drawing image update supports the observer by reading text.

[0035] The inventive method and apparatus are applicable in all devices which are using four-pigment system (or even more) media. Electrophoretic media are used in eReader, image frames, signage electronics, wearable electronics, and communication electronics.

[0036] The invention will be explained in more detail using an exemplary embodiment.

[0037] The appended drawings show Fig. 1Composition of a 2-pigment microcapsule (black and white) and a 4-pigment microcapsule system (prior art); Fig. 2Theory of particle movement in electrophoretic media (prior art); Fig. 3Color Filter Theory in advanced color electrophoretic microcapsules (prior art); Fig. 4Resulting voltage over media, while using ACVcom mode with different source voltages; Fig. 5Setup for the multi-level source driver integrated circuit with connected display according to the invention; Fig. 6Voltage level sequence for switching a pixel of an ACeP display system from a color A to a color B according to the invention; Fig. 7Inventive setup control for the multi-level-source driver IC by a controller; Fig. 8Voltage level sequences, so called waveforms to drive the ACeP 4-pigment media to a distinct color with an electronic circuit designed for driving only 2-pigment media; Fig. 9Voltage pulses to achieve white, black and blue color; Fig. 10Voltage pulses to achieve magenta, red, green and yellow color according to the inventive method.

[0038] Figure 5 shows a setup for the multi-level source driver integrated circuit 17 according to the invention. To realize the multi-source voltage supply, a multi-level source driver IC 17 is connected to a back electrode of the display system 1 beneath the 4-pigment media. Further, the multi-level source driver IC 17 is supplied by positive and negative low and high voltages on N1, N2 and P1, P2. To address the different source voltages, the multi-level source driver IC 17 has an 8-bit wide data input bus controlled by the controller. Since each pixel needs a 4-bit wide data word, e. g. D0...D3 or D4...D7, to address either 0V or positive / negative low or high voltage, the information of two pixel per clock can be transmitted to the multi-level source driver IC 17 by the controller.

[0039] Figure 6 on the right side shows a setup for a 4-pigment medium in an electrophoretic display system 1 with white 12, cyan 16, magenta 14 and yellow 15 nanoparticles. The different colors are presented by different hachures and additionally by the reference signs. The setup comprises a top transparent electrode 5, a bottom electrode 6 which functions as a top pixel electrode of the backplane 7, whereas each pixel of the display system 1 is controlled by a driver IC 17 which controls thin film transistors 9 to switch the applied voltage between the top- 5 and bottom 6 electrode. Due to the combination of the controller with the pre- 21 and post-image 22 buffer and the look-up table 23, the voltage between top- 5 and bottom- 6 electrode can also be set to -30V, -15V, 0V, +15V and +30V in parallel so that five different voltage levels can be applied on the media. As a result, the multi-level source driver IC 17 of the backplane 7 can be switched between -30V, -15V, 0V, +15V and +30V in parallel. According to the applied voltage between the top- 5 and bottom- 6 electrode, which influences the strength of the electrical field E, the velocity of the differently charged nanoparticles depends on the different mobilities µ of the nanoparticles v = µ · E. If a voltage pulse of +15V is applied to the bottom electrode 6 the negatively charged white nanoparticles 12 move to the bottom electrode 6 and the positively charged cyan nanoparticles 16 move to the top electrode 5. If simultaneously a voltage pulse of +30V is applied to the bottom electrode 6 and the TPCOM interface 10 is set to - 15V the negatively charged yellow nanoparticles 15 move to the bottom electrode 6 and the positively charged magenta nanoparticles 14 move to the top electrode 5 (see Fig. 6, left side). The color changes require not so many phases, resulting in a shorter refresh time and less image flickering during an image update. The biggest advantage is that an only 2-pigment driver IC can be used instead of developing an IC for controlling more than 2-pigment media.

[0040] Figure 7 shows the setup for controlling the multi-level-source driver IC 17 by a controller using a pre- 21 and post-image 22 buffer as well as a look-up table 23. The post- and pre-color levels are defined as values between 0 <= n <= 15, whereas n is a natural number. Hence, a typical source and target color is defined as value in between 0 ... 15. According to the example shown in Fig. 7 white color correspond to value 15, blue to value 13, red to value 3, green to value 7 and black to value 0. The information for updating the pixels of the display system 1 is generated by filling the pre-image buffer 21 with a target image, but with doubled source line size. E. g. an image with 480 source lines is stretched to a width of 960 source lines. Hence, the pre-image buffer 21 is filled with two times 15, two times 13, two times 3 and two times 7 for the first line, respectively. Every single pixel on the display area is represented by two pixels in the electronic memory. The post-image buffer 22 is filled alternating with 0 and 1 in order to define the voltage level sequence from a target color to 0 and the voltage level sequence from a target color to 1. These transitions are stored in a look-up table 23. The inventive method allows that 2-bits from the 1st pixel and 2-bits form the 2nd pixel in the controller representing the 4-bits required for one pixel on the display.

[0041] Figure 8 shows a table with voltage level sequences, so called waveforms to drive the ACeP 4-pigment media to a distinct color with an electronic circuit designed for driving only 2-pigment media. An example will be described in the following for i. e. switching from any previous color to green.

[0042] In a first step the old image content is cleared by applying -30V for the duration of two times 5 frames (1...5 and 6...10) and +30V for the duration of two times 5 frames (11... 15 and 16...20) to the top pixel electrode. In a second step the waveform for the target color green is driven. Therefore -30V is applied for the duration of four times 5 frames (21... 25, 26... 30, 31... 35 and 36... 40) and +15V is applied for the duration of two times 5 frames (41... 45 and 46...50) to the top pixel electrode.

[0043] Fig. 9 shows firstly in the upper picture-line the transition from DMBB (DarkMagentBlueBlack) over yellow to blue and secondly in the lower picture-line the transition from DMBB over white to black.

[0044] Regarding the upper picture-line of Fig. 9: In a first step, the voltage over media is set to -30V. The fast-moving negative charged yellow particles moving to the top, followed by the slow-moving negative charged white particles. The incoming light is now filtered by the yellow particles and reflected by the white particles. In a second step (lower picture-line), the voltage over media is 30V. The fast-moving positive charged magenta particles move to the top, followed by the slow-moving positive charged cyan particles. The incoming light is now filtered by the magenta and cyan particles and reflected by the white particles.

[0045] Regarding the lower picture-line of Fig. 9: In a first step, the voltage over media is set to -15V. The low-charged but slow-moving particles white and cyan started moving and the white reflecting particles moved to the top. Incoming light is reflected on the top and the media appears white. In a second step, the voltage over the media is set to +15V. The slow charged but slow-moving particles white and cyan starts moving and interchange their position in the stack. Finally, cyan particles are on the top and white particles are on the bottom. Incoming light is now filtered by the cyan, magenta and yellow particles until it is reflected by the white particles on the bottom. Since theoretically all wavelength of the incoming light is filtered out, the media looks black.

[0046] Fig. 10 shows firstly in the upper picture-line the transition from DMBB (DarkMagentBlueBlack) over magenta to red and secondly in the lower picture-line the transition from DMBB over yellow to green.

[0047] Regarding the upper picture-line of Fig. 10: In a first step, a short -15V voltage pulse is applied on the media. The low charged but slow moving particles white and cyan interchanging their position that white particles move over cyan particles. Incoming light is now filtered by the magenta particles and reflected by the underlying white particles. The media appears magenta. In a second step, a very short +30V voltage pulse is applied on the media. The slow moving particles cyan and white remain on their position but the fast moving yellow particles move to the top. Incoming light is now filtered by the yellow and magenta particles and reflected on the white particles below. Only red light can pass the yellow and magenta filter particles and the media appears red.

[0048] Regarding the lower picture-line of Fig. 10: In a first step, the voltage over media is -30V. The fast-moving negative charged yellow particles moving to the top, followed by the slow-moving negative charged white particles. The incoming light is now filtered by the yellow particles and reflected by the white particles. In a second step, a short positive voltage pulse of +15V is applied to the media. The low charged but slow moving cyan and white particles start moving and interchange their position in the stack. Finally, the white particles move below the cyan particles. The incoming light is filtered by the yellow and cyan particles and finally reflected by the white particles. Only green light can pass the yellow and cyan filter particles and the media appears green.List of Reference Signs

[0049] 1electrophoretic display system 2microcapsule 3pigments, nanoparticles 4clear fluid 5top electrode 6bottom electrode 7backplane 8kickback voltage 9switching transistors 10reference electrode / TPCOM interface 11voltage level sequence 12white nanoparticles 13black nanoparticles 14magenta nanoparticles 15yellow nanoparticles 16cyan nanoparticles 17multi-level source driver IC 18source line 19gate line 20pixel of the display system 21pre-image buffer 22post-image buffer 23look-up table

Claims

1. A method for fast and smart advanced color electrophoretic, ACeP, switching of a 3- or 4-pigment medium in an electrophoretic display system (1) by an electronic circuitry designed for driving an only 2-pigment medium, whereas the display system (1) comprises a transparent top electrode (5), a bottom electrode (6) and the 3- or 4-pigment medium (3) between the top (5) and bottom (6) electrode, whereas the electronic circuitry comprises a memory configured to store images, a controller configured to control a multi-level source driver integrated circuit, IC (17), which is connected to switching transistors (9) of pixels of the display system (1), the method uses a multi-level source mode of the multi-level source driver IC (17) and comprises the following steps: - filling a pre-image buffer (21) of the electronic circuitry with a target image of the display system (1), whereas every single pixel of the display system (1) is represented by two pixels in the pre-image buffer (21) of the electronic circuitry, and - filling a post-image buffer (22) of the electronic circuitry alternating with 0 and 1, and - defining voltage level sequences depending on post and pre color levels of displayed images on the display system (1) and storing them in a look-up table (23) of the electronic circuitry, wherein - a single pixel of the display system (1) is addressed with a 4-bit wide data word by the multi-level source driver IC (17), whereas the 4-bits are concatenated by 2-bits of the pre-image buffer (21) and 2-bits of the post-image buffer (22) to address different source voltages so that each single pixel of the display system (1) can be supplied by at least five different source voltages.

2. The method for fast and smart ACeP switching a 3- or 4-pigment medium in an electrophoretic display system (1) according to claim 1, wherein the multi-level source driver IC (17) is supplied by a positive high voltage P1, a positive low voltage P2, a negative high voltage N1 and a negative low voltage N2, respectively, whereas the multi-level source driver IC (17) comprises an 8-bit wide data input bus for addressing more than four different source voltages for switching the pixels of the display system (1).

3. The method for fast and smart ACeP switching a 3- or 4-pigment medium in an electrophoretic display system (1) according to claim 1 or 2, wherein the controller controls the multi-level source driver IC (17), which outputs five voltage levels in parallel, especially -30V, -15V, 0V, +15V, +30V.

4. The method for fast and smart ACeP switching a 3- or 4-pigment medium in an electrophoretic display system (1) according to claim 2, wherein information of two pixels of the display system (1) per clock is transmitted to the multi-level source driver IC (17).

5. The method for fast and smart ACeP switching a 3- or 4-pigment medium in an electrophoretic display system (1) according to one of the former claims, wherein post and pre color levels are defined as values between 0 <= n <= 15, whereas n is a natural number.

6. The method for fast and smart ACeP switching a 3- or 4-pigment medium in an electrophoretic display system (1) according to one of the former claims, wherein a length of the voltage level sequences to vary a color of one pixel to another color has to be the same, whereas if a target color is reached by a shorter voltage level sequence, said voltage level sequence is filled with Null frames.

7. The method for fast and smart ACeP switching a 3- or 4-pigment medium in an electrophoretic display system (1) according to claim 5, wherein positive / negative high / low voltage pulses to achieve a black color should be come prior to its Null Frames.

8. An apparatus for fast and smart advanced color electrophoretic, ACeP, switching of a 3- or 4-pigment medium in an electrophoretic display system (1) by an electronic circuitry designed for driving an only 2-pigment medium, whereas the display system (1) comprises a transparent top electrode (5), a bottom electrode (6) and the 3- or 4-pigment medium between the top (5) and bottom (6) electrode, whereas the electronic circuitry comprises a memory configured to store images, a controller configured to control a multi-level source driver integrated circuit, IC (17), which is connected to switching transistors (9) of pixels of the display system (1), a pre-image buffer (21) configured to buffer a target image of the display system (1), a post-image buffer (22) configured to store alternating 0 and 1, and a look-up table (23) configured to store post- and pre- color levels of displayed images on the display system (1), wherein the apparatus is configured to perform the method according to one of the claims 1 to 7.

Images