Electrophoretic display apparatus and method of controlling electrophoretic display apparatus

Abstract

The electrophoretic display apparatus for displaying images comprises: a common electrode to which a common voltage is supplied; a pixel electrode arranged to correspond to the common electrode; a plurality of color pigments provided between the common electrode and the pixel electrode and dispersed in a solvent; a data driving unit for supplying a driving voltage to the pixel electrode; a voltage compensation unit for compensating for the driving voltage supplied to the data driving unit; a first sensor unit and a second sensor unit for repeatedly sensing first sensing data and second sensing data; a memory for cumulatively storing the first sensing data and the second sensing data as accumulated first sensing data and accumulated second sensing data; and a control unit for controlling the voltage compensation unit to compensate for the driving voltage by supplying a compensation voltage.

Description

Electrophoretic display device and control method of electrophoretic display device

[0001] The disclosed invention relates to an electrophoretic display device and a method for controlling the electrophoretic display device.

[0002] Electrophoretic Displays (EPDs) are display technologies that utilize the electrophoretic phenomenon to display characters or images by moving charged microparticles using an electric field. When an electric field is applied, the particles move and colors appear, and since the state is maintained even after the electric field is removed, no power is consumed in static images. Thanks to these low-power characteristics, they are widely used in electronic paper (E-paper), such as in e-book readers.

[0003] In order to reproducibly align or initialize multiple color pigments dispersed in a solvent between the common electrode and the pixel electrode of the display panel of an electrophoretic display device to a specific position, positive and negative high voltages are switched at high speed on the pixel electrode.

[0004] Conventionally, the electrical characteristics of color pigments, solvents, and switching elements in display panels change due to high / low temperature environments or long-term operation. Consequently, it becomes difficult to move color pigments to the desired speed and position using conventional driving waveforms, leading to degraded image quality, visual discomfort caused by flickering during operation, and increased power consumption. These problems ultimately result in increased power consumption of the display panel, as well as reduced long-term lifespan and reliability.

[0005] The present disclosure provides an electrophoretic display device and a method for controlling the electrophoretic display device that can improve the long-term lifespan and reliability of the electrophoretic display device.

[0006] The technical problems to be solved in this document are not limited to those mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art to which this invention belongs from the description below.

[0007] An electrophoretic display device according to one embodiment of the present disclosure is an electrophoretic display device for displaying images, comprising: a common electrode to which a common voltage is supplied; a pixel electrode disposed corresponding to the common electrode; a plurality of color pigments disposed between the common electrode and the pixel electrode and dispersed in a solvent; a data driving unit that supplies a data voltage of one frame among a plurality of frames of any one of the images to the pixel electrode; a voltage compensation unit that compensates the driving voltage supplied to the data driving unit; a first sensor unit that repeatedly detects first detection data including at least one of a first current and a first voltage on the power side of the data driving unit; a second sensor unit that repeatedly detects second detection data including at least one of a second current and a second voltage of the common electrode; and a memory that corresponds the repeatedly detected first detection data and the repeatedly detected second detection data to each other and cumulatively stores them as accumulated first detection data and accumulated second detection data. and a control unit configured to compensate the driving voltage supplied to the data driving unit by supplying a compensation voltage based on the accumulated first detection data and the accumulated second detection data, thereby ensuring that at least one of the first detection data and the second detection data reaches a set reference data.

[0008] A control method for an electrophoretic display device according to one embodiment of the present disclosure is a control method for an electrophoretic display device for displaying images, comprising: supplying a common voltage to a common electrode; supplying a driving voltage to a data driving unit that supplies a data voltage of one frame among a plurality of frames of one of the images to a pixel electrode; supplying the data voltage to the pixel electrode; repeatedly detecting a first detection data including at least one of a first current and a first voltage on the power side of the data driving unit; repeatedly detecting a second detection data including at least one of a second current and a second voltage of the common electrode; and matching the repeatedly detected first detection data and the repeatedly detected second detection data with each other to cumulatively store the accumulated first detection data and the accumulated second detection data. It may include controlling the voltage compensation unit to compensate the driving voltage supplied to the data driving unit by supplying a compensation voltage based on the accumulated first detection data and the accumulated second detection data, so that at least one of the first detection data and the second detection data reaches a set reference data.

[0009] FIG. 1 is a configuration diagram of an electrophoretic display device according to one embodiment.

[0010] FIG. 2 illustrates a pixel of an electrophoretic display device according to one embodiment.

[0011] FIG. 3 is a control block diagram of an electrophoretic display device according to one embodiment.

[0012] FIG. 4 illustrates the waveform of a data voltage supplied from a data driving unit to a pixel electrode in an electrophoretic display device according to one embodiment.

[0013] FIG. 5 illustrates the voltage level and charge / discharge sequence of a data voltage waveform supplied to a pixel electrode from a data driving unit of an electrophoretic display device according to one embodiment.

[0014] FIG. 6 is a configuration diagram of the voltage compensation unit of the power supply unit of an electrophoretic display device according to one embodiment.

[0015] FIG. 7 is a circuit diagram of a voltage compensation unit of an electrophoretic display device according to one embodiment.

[0016] FIG. 8 is a circuit diagram of a stabilization circuit of an electrophoretic display device according to one embodiment.

[0017] FIG. 9 is an example of a flowchart for a control method of an electrophoretic display device according to one embodiment.

[0018] FIG. 10 illustrates a section for detecting changes in electrical characteristics during charging and discharging of a capacitive load in an electrophoretic display device according to one embodiment.

[0019] FIG. 11 illustrates compensating the driving voltage supplied to the data driving unit in an electrophoretic display device according to one embodiment.

[0020] The embodiments described in this specification and the configurations illustrated in the drawings are merely preferred examples of the disclosed invention, and various modifications that may replace the embodiments and drawings of this specification may exist at the time of filing this application.

[0021] Additionally, the same reference numerals or symbols presented in each drawing of this specification represent parts or components that perform substantially the same function.

[0022] Additionally, the singular form of the noun corresponding to the item may include one or multiple items, unless the relevant context clearly indicates otherwise.

[0023] Additionally, in this document, each of the phrases such as "A or B", "at least one of A and B", "at least one of A or B", "A, B or C", "at least one of A, B and C", and "at least one of A, B, or C" may include any one of the items listed together in the corresponding phrase, or all possible combinations thereof.

[0024] Additionally, the terms "part," "module," and "component" may be implemented in hardware or software. Depending on the embodiments, a plurality of "parts," "modules," and "components" may be implemented as a single component, or a single "part," "module," or "component" may include a plurality of components.

[0025] Furthermore, the terms used in this specification are for describing embodiments and are not intended to limit or / or restrict the disclosed invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as "comprising" or "having" are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and do not preclude the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0026] Additionally, terms including ordinal numbers, such as "first," "second," etc., used herein may be used to describe various components, but said components are not limited by said terms, and said terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. The term "and / or" includes a combination of a plurality of related described items or any one of a plurality of related described items.

[0027] Where any (e.g., 1st) component is referred to as "coupled" or "connected" to another (e.g., 2nd) component, with or without the terms "functionally" or "communicationly," it means that said any component may be connected to said other component directly (e.g., via a wire), wirelessly, or through a third component.

[0028] When it is said that a component is "connected," "combined," "supported," or "in contact" with another component, this includes not only cases where the components are directly connected, combined, supported, or in contact, but also cases where they are indirectly connected, combined, supported, or in contact through a third component.

[0029] When it is said that a component is located "on" another component, this includes not only cases where one component is in contact with the other, but also cases where another component exists between the two components.

[0030] Meanwhile, terms such as "up / down direction" and "front / back direction" used in the following description are defined based on the drawings, and the shape and position of each component are not limited by these terms. For example, the terms "front" and "rear" below may each be defined based on the X direction shown in the drawings. The terms "up" and "down" below may each be defined based on the Z direction shown in the drawings. The terms "left direction" and "right direction" below may be defined based on the Y direction shown in the drawings. The term "vertical direction" below may each refer to the Z direction shown in the drawings, and the term "horizontal direction" below may each refer to the Y direction shown in the drawings.

[0031] Hereinafter, embodiments according to the present invention will be described in detail with reference to the attached drawings.

[0032] FIG. 1 is a configuration diagram of an electrophoretic display device according to one embodiment.

[0033] Referring to FIG. 1, the electrophoretic display device (1) is a device capable of visually displaying characters or images. In the following examples, the electrophoretic display device (1) is an electronic paper, but is not limited thereto. The form of the display device (1) is not limited as long as it is a device capable of visually displaying images.

[0034] The electrophoretic display device (1) may include a display panel (10), a panel display driver integrated circuit (PDDI) (20), a control unit (30), and a power supply unit (40).

[0035] The display panel (10) may include m / n pixels (11).

[0036] A display panel (10) may be formed such that a plurality of data lines (D1 to Dm) and a plurality of gate lines (G1 to Gn) intersect. A TFT may be electrically connected to each pixel (11) in the intersecting area.

[0037] The panel driver (20) can transmit electrical signals to each pixel (11) in the correct time and order according to the control of the control unit (30).

[0038] The control unit (30) may receive a control signal from the central processing unit (AP or CPU) of the electrophoretic display device (1). The control unit (30) may include a memory, a processor, and a control circuit board on which these are mounted.

[0039] The control unit (30) can generate a driver control signal (gate control signal, data control signal) for controlling the panel driver (20) based on the provided control signal and provide the driver control signal to the panel driver (20).

[0040] The power supply unit (40) can supply power to the display panel (10), the panel driver (20), and the control unit (30).

[0041] When power is supplied to the electrophoretic display device (1), the power supply unit (40) can generate voltages required for driving the display panel (10) using the input power. The power supply unit (40) can generate driving voltages according to the power control signal provided by the control unit (30).

[0042] The power supply unit (40) can supply a driving voltage to the panel driver (20). For example, the power supply unit (40) can generate a plurality of driving voltages to apply an electric field to a charged color pigment of a pixel (11) of a display panel (10) and supply them to the panel driver (20) to output a waveform for determining the position of the charged color pigment.

[0043] The panel driver (20) may include a gate driver (21) and a data driver (22).

[0044] The gate driver (21) can supply a gate voltage to a plurality of gate lines (G1 to Gn) of the display panel (10) according to a gate control signal provided from the control unit (30). The gate driver (21) can select the TFT of the corresponding line and turn it on or off.

[0045] When the gate driving unit (21) applies a gate voltage to the gate lines (G1 to Gn), the TFT is turned on or turned off by the applied gate voltage, and the pixel (11) of the corresponding line can be driven.

[0046] The data driving unit (22) can supply waveforms to a plurality of data lines (D1 to Dm) of the display panel (10) according to a data control signal provided from the control unit (30).

[0047] The electrophoretic display device (1) can supply a waveform to a specific pixel (11) using a gate driver (21) and a data driver (22). The waveform can be generated in various versions by reflecting the characteristics of the charged color pigment of the pixel (11) and the solvent, the characteristics of the solvent manufacturer's unique manufacturing process, and the operating temperature. For example, control information for implementing a waveform to display white, blue, red, and yellow on the pixel (11) may be stored in advance.

[0048] The control unit (30) can provide control information for implementing a waveform to the gate driver (21) and the data driver (22). The control unit (30) can perform control to create a waveform implemented as a sequence of positive (+) and negative (-) voltages in a series of reset and write sections to move a charged color pigment to a desired position.

[0049] The data driving unit (22) can generate a waveform using waveform control information from the control unit (30) and a driving voltage supplied from the power supply unit (40), and can supply the generated waveform to a plurality of data lines (D1 to Dm).

[0050] FIG. 2 illustrates a pixel of a display panel of an electrophoretic display device according to one embodiment.

[0051] Referring to FIG. 2, the display panel (10) may include a pixel electrode (12) provided on a lower substrate and a common electrode (13) on an upper substrate.

[0052] The pixel electrode (12) and the common electrode (13) can be positioned opposite each other.

[0053] The common electrode (13) provided on the upper substrate can be placed on the side visible to the user as a transparent electrode layer.

[0054] A series of electric fields can be formed in the pixel (11) by the potential difference between the common voltage of the common electrode (13) and the waveform of the pixel electrode (12). This electric field can guide color pigments placed between the common electrode (13) and the pixel electrode (12) to a desired position, thereby enabling the realization of a desired color by utilizing external light reflection.

[0055] Between the common electrode (13) and the pixel electrode (12), color pigments charged with a preset capacitance can be dispersed in a solvent to form an electrophoretic layer.

[0056] The color pigments of the electrophoretic layer can each be charged with positive (+) or negative (-) charges of different polarities and capacities. When a waveform is applied through the data driver (22), the color pigments move due to the difference in electric field with the common electrode (13) and can realize a desired color using external light reflection.

[0057] For example, multiple color pigments may include four color particles (W, B, R, Y).

[0058] The four color particles (W, B, R, Y) may include two pairs of particles with opposite polarities.

[0059] The first pair may include a white particle (W) and a blue particle (B). The white particle (W) may have a high positive (+) charge, and the blue particle (B) may have a high negative (-) charge.

[0060] The second pair may include a red particle (R) and a yellow particle (Y). The red particle (R) may have a low positive (+) charge, and the yellow particle (Y) may have a low negative (-) charge.

[0061] In various embodiments, the white particles (W), blue particles (B), red particles (R), and yellow particles (Y) can be of various shapes.

[0062] The four color particles (W, B, R, Y) can be mixed to adjust the color state. The four colors (W, B, R, Y) can be extended to other colors in addition to white, blue, red, and yellow.

[0063] For example, when a high negative (-) potential is applied to the pixel electrode (12) compared to the common voltage of the common electrode (13), a high electric field is generated, causing negative (-) charged blue particles (B) to move toward the common electrode (13) and high positive (+) charged white particles (W) to move toward the pixel electrode (12). Since red (R) and yellow particles (Y) have a small capacitance, less force is applied in the same electric field compared to high positive (+) charged white particles (W) and high negative (-) charged blue particles (B), so the distance traveled to the common electrode (13) is shorter relative to the time. Finally, the movement of blue particles (B) toward the common electrode (13) is concentrated for a specific period of time, and is displayed to the user as blue through external light reflection.

[0064] In addition, when a high positive (+) potential is applied to the pixel electrode (12) compared to the common voltage of the common electrode (13), a high electric field of opposite polarity is generated, and the particle distribution appears opposite to the previous one. Finally, it is displayed to the user as white through external light reflection.

[0065] Additionally, when a low positive (+) potential is applied to the pixel electrode (12) in comparison to the common voltage of the common electrode (13), a low electric field is applied to the blue particles (B) with a high negative (-) charge, thereby restricting their movement toward the pixel electrode (12). The white particles (W) with a high positive (+) charge are also restricted from moving toward the common electrode (13) for the same reason. This is because the low electric field is not strong enough to overcome the strong attractive force between the two particles. On the other hand, the low electric field is sufficient to separate the yellow particles (Y) with a low negative (-) charge and the red particles (R) with a low positive (+) charge, so the red particles (R) with a low positive (+) charge move toward the common electrode (13), and the yellow particles (Y) with a low negative (-) charge move toward the pixel electrode (12). Finally, to the user, it is displayed in red through external light reflection.

[0066] In addition, when a low negative (-) potential is applied compared to the common voltage of the common electrode (13), a low electric field of opposite polarity is generated, and the particle distribution appears reversed from before. Finally, it is displayed to the user as yellow through external light reflection.

[0067] FIG. 3 is a control block diagram of an electrophoretic display device according to one embodiment.

[0068] Referring to FIG. 3, the power supply unit (40) can supply a driving voltage to the data driving unit (22).

[0069] The data driving unit (22) can be electrically connected to the source electrode of the TFT (14) through a data line.

[0070] The drain electrode of the TFT (14) can be electrically connected to the pixel electrode (12).

[0071] In various embodiments, the source electrode of the TFT (14) is electrically connected to the pixel electrode (12), and the drain electrode of the TFT (14) can be electrically connected to the data driver (22).

[0072] The gate electrode of the TFT (14) can be electrically connected to the gate driver (21).

[0073] The TFT (14) can be turned on or turned off by the gate voltage output from the gate driver (21). The data driver (22) can generate a data voltage having a waveform using the driving voltage supplied from the power supply (40).

[0074] When the TFT (14) is turned on, the data voltage output from the data driving unit (22) can be supplied to the pixel electrode (12) through the TFT (14).

[0075] A common voltage (Vcom) can be supplied to the common electrode (12). The common voltage can be a DC voltage or an AC voltage. The common electrode (12) can receive the common voltage from the power supply unit (40).

[0076] Accordingly, an electric field can be formed in the pixel (11) by the potential difference between the data voltage of the pixel electrode (12) and the common voltage of the common electrode (13).

[0077] In the pixel (11), the common electrode (13) and the source electrode of the TFT (14) can be formed as a capacitive load. In various embodiments, the capacitive load can be formed between the common electrode (13) and the pixel electrode (12).

[0078] In order to reproducibly align multiple color pigments of a pixel (11) to a specific position or move them to an initial position, it is necessary to switch high voltages (e.g., +20V, -20V) of positive (+) and negative (-) symmetrical to the common voltage of the common electrode (13) at high speed (e.g., 85Hz). Additionally, depending on the characteristics or environment of the pixel (11), high-speed operation can be performed for as short as a few seconds (e.g., 15 seconds) to several minutes. At this time, pulsed charge / discharge currents (sourcing current / sinking current) of several amperes (e.g., 2.5A) generated during the high-voltage switching of each positive electrode must be stably supplied and recovered.

[0079] FIG. 4 illustrates the waveform of a data voltage supplied from a data driving unit to a pixel electrode in an electrophoretic display device according to one embodiment.

[0080] Referring to FIG. 4, in order to move a desired color pigment among a plurality of color pigments to the common electrode (13), the color pigments located at the common electrode (13) must be rapidly moved to a neutral position or an initial position. To do this, a high-voltage positive data voltage must be applied continuously for a long time while inverting between a positive (+) voltage and a negative (-) voltage, which is called the reset section. Afterwards, in order to move a specific charged color pigment to be expressed to the common electrode (13), a waveform of a data voltage corresponding to a preset amount of charge must be applied to the pixel electrode (12), which is called the writing section.

[0081] The output of the data driving unit (22) is transmitted to the pixel electrode (12) via the TFT (14). When a potential difference is created between the data voltage of the pixel electrode (12) and the common voltage of the common electrode (13), an electric field is formed in the color pigments located between the pixel electrode (12) and the common electrode (13), causing the color pigments to move.

[0082] When a data voltage of the government is supplied to the pixel electrode (12) during the reset section and / or write section, the electric field applied to the color pigments existing between the pixel electrode (12) and the common electrode (13) can be changed. Accordingly, rapid charging and discharging operations occur in the capacitive load according to the potential difference relationship between the common electrode (13) and the pixel electrode (12), and a change in current occurs due to the movement of charge.

[0083] The data driving unit (22) can generate a data voltage supplied to the pixel electrode (12) using driving voltages generated by the power supply unit (40). The data voltage can be repeated based on the common voltage within the range of positive (+) voltage (e.g., +19V) and negative (-) voltage (e.g., -19V) to move the charged color pigment to the common electrode (13), and can have multiple voltage levels depending on the charge amount of the charged color pigments. The positive (+) voltage (Vpos) of the data voltage can have multiple voltage levels. The negative (-) voltage (Vneg) of the data voltage can have multiple voltage levels.

[0084] FIG. 5 illustrates a data voltage of multiple voltage levels and a charge / discharge sequence supplied to a pixel electrode from a data driving unit of an electrophoretic display device according to one embodiment.

[0085] Referring to Fig. 5, the data voltage may have a waveform that rises in steps and falls in steps.

[0086] For example, the voltage levels of the data voltage waveform may include six voltage levels: Vh_high, Vh_medium, Vh_low, Vl_low, Vl_medium, and Vl_high. Vh_high, Vh_medium, and Vh_low may be positive (+) voltages. In this case, the voltage values ​​may be higher in the order of Vh_high, Vh_medium, and Vh_low (Vh_high > Vh_medium > Vh_low). Additionally, Vl_low, Vl_medium, and Vl_high may be negative (-) voltages. In this case, the voltage values ​​may be higher in the order of Vl_low, Vl_medium, and Vl_high (Vl_low > Vl_medium > Vl_high).

[0087] As illustrated in FIG. 5(a), the waveform of the data voltage may include a rising pattern in which the voltage value rises from Vh_low to Vh_medium and a rising pattern in which the voltage value rises from Vh_medium to Vh_high even within a positive (+) voltage (Vpos). The waveform of the data voltage may also include a rising pattern in which the voltage value rises from Vl_high to Vl_medium and a rising pattern in which the voltage value rises from Vl_medium to Vl_low even within a negative (-) voltage (Vneg).

[0088] As illustrated in FIG. 5(b), the waveform of the data voltage may include a falling pattern in which the voltage value falls from Vh_high to Vh_medium and a falling pattern in which the voltage value falls from Vh_medium to Vh_low even within a positive (+) voltage (Vpos). The waveform of the data voltage may also include a falling pattern in which the voltage value falls from Vl_low to Vl_medium and a falling pattern in which the voltage value falls from Vl_medium to Vl_high even within a negative (-) voltage (Vneg).

[0089] Additionally, the waveform of the data voltage may include various rising patterns, such as a rising pattern in which the voltage value rises from Vh_low to Vh_high, a rising pattern in which it rises from Vl_high to Vl_low, and a rising pattern in which it rises from Vl_high to Vh_high. The waveform of the data voltage may also include various falling patterns, such as a falling pattern in which it falls from Vh_high to Vh_low, a falling pattern in which it falls from Vl_low to Vl_high, and a falling pattern in which it falls from Vh_high to Vl_high.

[0090] Referring again to FIG. 3, the power supply unit (40) can generate a multi-voltage level driving voltage using the input power and supply the multi-voltage level driving voltage to the data driving unit (22).

[0091] The data driving unit (22) can generate a data voltage having a waveform composed of a series of voltage waveforms using the driving voltage supplied from the power supply unit (40) and supply it to the pixel electrode (12) of the pixel (11). The data voltage may include a waveform in which high voltages of positive (+) polarity and negative (-) polarity alternate. The positive (+) voltage and negative (-) voltage of the data voltage may each have multiple voltage levels. Accordingly, the voltage level of the driving voltage supplied from the power supply unit (40) to the data driving unit (22) may also have multiple voltage levels.

[0092] For example, the multi-voltage level driving voltage may include six voltage levels, such as Vh_high, Vh_medium, Vh_low, Vl_low, Vl_medium, and Vl_high, just like the voltage levels of the data voltage waveform.

[0093] Generally, the movement of the color pigment changes during operation and storage and operation at temperatures above or below a certain temperature. The amount of charge charged on the color pigment or the chemical bonding characteristics of the pigment and solvent decrease and change due to the operating environment, such as temperature, humidity, and electrical stress. As a result, even if an initially set electric field is applied, the operating characteristics of the color pigment change, making it difficult to move to a set position.

[0094] As such, changes in the charge of the pigment, the properties of the solvent, and the characteristics of the TFT occur due to high / low temperature environments or long-term operation. These characteristic changes vary by display panel production lot and, in severe cases, by panel, making it difficult to determine the time and voltage for optimal operation. Furthermore, if it is difficult to change the voltage (electric field) applied across the color pigment, operation requiring the application of voltage (electric field) for an extended period becomes necessary. Consequently, a sense of unease arises due to flickering during operation, electrical stress increases, accelerating characteristic changes, and power consumption also increases.

[0095] An electrophoretic display device (1) according to one embodiment can compensate for the voltage supplied to the data driving unit (22) even if the electrical characteristics of the color pigments, solvent, and switching element of the display panel (10) change due to electrical stress caused by high / low temperature and high humidity environments or long-term operation, thereby compensating for the degree of afterimage and color change caused by changes in electrical characteristics, suppressing the increase in power consumption, and improving long-term lifespan and reliability.

[0096] An electrophoretic display device (1) according to one embodiment may include a first sensor unit (70) and a second sensor unit (80).

[0097] The first sensor unit (70) can be provided between the power supply unit (40) and the data driving unit (22).

[0098] The first sensor unit (70) can detect current and / or voltage between the power supply unit (40) and the data driving unit (22). The first sensor unit (70) can detect current and / or voltage on the power side of the data driving unit (22) connected to the output side of the power supply unit (40). The first sensor unit (70) can be provided to correspond to the voltage compensation unit (50). For example, if there are multiple voltage compensation units (50), there may also be multiple first sensor units (70). If there are six voltage compensation units (50), there may also be six first sensor units (70).

[0099] The first sensor unit (70) may include a first current sensor (71) and / or a first voltage sensor (72).

[0100] The first current sensor (71) can detect the current on the power side of the data driving unit (22). The first voltage sensor (72) can detect the voltage on the power side of the data driving unit (22). For example, the first current sensor (71) may include a current transformer (CT), a shunt resistor, a Hall sensor, etc.

[0101] The second sensor unit (80) may be provided between the common electrode (13) and the stabilization circuit (60). The stabilization circuit (60) may be a circuit for stabilizing the potential of the common electrode (13).

[0102] The second sensor unit (80) can detect the current and / or voltage of the common electrode (13).

[0103] The second sensor unit (80) may include a second current sensor (81) and / or a second voltage sensor (82).

[0104] The second current sensor (81) can detect the current of the common electrode (13). The second voltage sensor (82) can detect the voltage of the common electrode (13).

[0105] The control unit (30) may include a processor (31) and a memory (32). The processor (31) is hardware and may include logic circuits and arithmetic circuits. The processor (31) can control electrically connected components of the electrophoretic display device (1) using programs, instructions, and / or data stored in the memory (32) for the operation of the electrophoretic display device (1). The processor (31) and the memory (32) may be implemented as separate chips or as a single chip. Additionally, the control unit (30) may include a plurality of processors and a plurality of memories.

[0106] The memory (32) can store programs, applications, and / or data for the operation of the electrophoretic display device (1), and can store data generated by the processor (31). The memory (32) may include non-volatile memory such as ROM (Read Only Memory) and flash memory for storing data for a long period. The memory (32) may include volatile memory such as S-RAM (Static Random Access Memory) and D-RAM (Dynamic Random Access Memory) for temporarily storing data.

[0107] The control unit (30) can receive first current data on the power side of the data driving unit (22) detected by the first current sensor (71). The control unit (30) can receive first voltage data on the power side of the data driving unit (22) detected by the first voltage sensor (72).

[0108] The control unit (30) can receive the second current data of the common electrode (13) detected by the second current sensor (81).

[0109] The control unit (30) can receive second voltage data of the common electrode (13) detected by the second voltage sensor (82).

[0110] In addition, the electrophoretic display device (1) according to one embodiment may further include a third sensor unit (90) for detecting environmental information.

[0111] The third sensor unit (90) may include a temperature sensor (91) and / or a humidity sensor (92). The third sensor unit (90) may include an environmental sensor capable of detecting various forms of environmental data in addition to temperature and humidity.

[0112] The temperature sensor (91) can detect the temperature of the electrophoretic display device (1) or the display panel (10). For example, the temperature sensor (91) can detect the temperature of the area around the electrophoretic display device (1) or the display panel.

[0113] The humidity sensor (92) can detect the humidity of the electrophoretic display device (1) or the display panel (10). For example, the humidity sensor (92) can detect the humidity of the data driving unit (22).

[0114] The control unit (30) can receive temperature data of the electrophoretic display device (1) or the periphery of the display panel detected by the temperature sensor (91). The control unit (30) can receive humidity data of the data driving unit (22) detected by the humidity sensor (92).

[0115] In one embodiment, the control unit (30) can compensate the voltage supplied from the power supply unit (40) to the data driving unit (22) through the voltage compensation unit (50) based on the first current data detected by the first current sensor (71), the first voltage data detected by the first voltage sensor (72), the second current data detected by the second current sensor (81), and the second voltage data detected by the second voltage sensor (82). For example, the control unit (30) can store the first current data, the first voltage data, the second current data, and the second voltage data, determine the compensation voltage based on the first current data, the first voltage data, the second current data, and the second voltage data, or accumulate the first current data, the first voltage data, the second current data, and the second voltage data over time and determine the compensation voltage by analyzing the accumulated data using a statistical method, and compensate the voltage supplied to the data driving unit (22) through the voltage compensation unit (50) by the amount of the compensation voltage.

[0116] In various embodiments, the control unit (30) can compensate the voltage supplied to the data driving unit (22) through the voltage compensation unit (50) based on the first current data detected by the first current sensor (71) and the second current data detected by the second current sensor (81).

[0117] In various embodiments, the control unit (30) can compensate the supplied voltage supplied to the data driving unit (22) through the voltage compensation unit (50) based on the first voltage data detected by the first voltage sensor (72) and the second voltage data detected by the second voltage sensor (82).

[0118] In various embodiments, the control unit (30) may compensate the voltage supplied to the data driving unit (22) through the voltage compensation unit (50) based on the first current data detected by the first current sensor (71), the first voltage data detected by the first voltage sensor (72), the second current data detected by the second current sensor (81), the second voltage data detected by the second voltage sensor (82), the temperature data detected by the temperature sensor (91), and the humidity data detected by the humidity sensor (92). For example, the control unit (30) may store the first current data, the first voltage data, the second current data, the second voltage data, the temperature data, and the humidity data, and determine the compensation voltage based on the first current data, the first voltage data, the second current data, the second voltage data, the temperature data, and the humidity data, or accumulate the first current data, the first voltage data, the second current data, the second voltage data, the temperature data, and the humidity data over time and compensate by analyzing the accumulated data using a statistical method. The voltage can be determined, and the voltage supplied to the data driving unit (22) through the voltage compensation unit (50) can be compensated by the compensation voltage.

[0119] Accordingly, an electrophoretic display device (1) according to one embodiment detects a change in the electrical characteristics of a pixel (11) and, based on this, applies an additional voltage higher or lower than the normal driving voltage to compensate for particle movement characteristics, thereby minimizing the increase in driving time due to the change in characteristics of the pixel (11) and suppressing the sense of unease, afterimage, color change, and increase in power consumption.

[0120] Additionally, the control unit (30) can compensate the driving voltage before the driving section (reset section and write section) begins. For example, a compensation voltage can be applied to the driving voltage during the power boot phase. This allows for stable operation from the start of driving by pre-setting the voltage compensation required before the system begins full-scale operation. That is, by applying the compensation voltage in advance during the system boot phase after the power is turned on, the voltage compensation can be completed before the driving section begins.

[0121] FIG. 6 is a configuration diagram of the voltage compensation unit of the power supply unit of an electrophoretic display device according to one embodiment.

[0122] Referring to FIG. 6, the power supply unit (40) can generate a plurality of positive driving voltages using an input power source (Vin) and supply the plurality of positive driving voltages to the data driving unit (22).

[0123] The power supply unit (40) may include a voltage compensation unit (50) that compensates the voltage supplied to the data driving unit (22).

[0124] The voltage compensation unit (50) can compensate the voltage supplied to the data driving unit (22) according to the control of the control unit (30). In various embodiments, the voltage compensation unit (50) may be embedded in the panel driver (20). For example, the voltage compensation unit (50) may be embedded in the data driving unit (22).

[0125] The voltage compensation unit (50) can be electrically connected to the data driving unit (22).

[0126] The voltage compensation unit (50) can output a compensation voltage with a compensated voltage level to the data driving unit (22).

[0127] The voltage compensation unit (50) may include a first voltage compensation unit (50_1) to an nth voltage compensation unit (50_n). The first voltage compensation unit (50_1) may output a first compensation voltage, which compensates for a driving voltage of a first voltage level, to the data driving unit (22). The second voltage compensation unit (50_2) may output a second compensation voltage, which compensates for a driving voltage of a second voltage level, to the data driving unit (22). The nth voltage compensation unit (50_n) may output an nth compensation voltage, which compensates for a driving voltage of an nth voltage level, to the data driving unit (22).

[0128] For example, the voltage compensation unit (50) can compensate at least one voltage level among six voltage levels of Vh_high, Vh_medium, Vh_low, Vl_low, Vl_medium, and Vl_high to the data driving unit (22), and output the compensated voltage with the voltage level compensated to the data driving unit (22).

[0129] Additionally, the voltage compensation unit (50) can supply a charging current to the capacitive load through the data driving unit (22) when the capacitive load of the pixel (11) is charged, and can absorb the discharge current coming into the data driving unit (22) when the capacitive load is discharged.

[0130] The voltage compensation unit (50) can perform a sourcing operation that supplies a charging current to the capacitive load when charging the capacitive load, or a sinking operation that absorbs a discharge current from the capacitive load when discharging the capacitive load.

[0131] The voltage compensation unit (50) generates a charging current supplied from the voltage compensation unit (50) to the data driving unit (22) through a sourcing operation when charging a capacitive load, and can supply the generated charging current to the capacitive load through the data driving unit (22).

[0132] The voltage compensation unit (50) can absorb the discharge current flowing from the capacitive load through the data driving unit (22) to the voltage compensation unit (50) through a sinking operation during the discharge of the capacitive load.

[0133] The voltage compensation unit (50) can stably supply peak charging and discharging currents in the positive and negative directions that occur during charging and discharging of the capacitive load by performing a sourcing operation when charging the capacitive load and automatically performing a sinking operation when discharging the capacitive load.

[0134] The capacitive load can repeat charging and discharging operations as the data voltage supplied to the pixel electrode (12) varies from frame to frame.

[0135] The voltage compensation unit (50) can perform a sourcing operation to supply a charging current to the data driving unit (22) based on the difference between the data voltage of the current frame and the data voltage of the previous frame, or a sinking operation to absorb a discharge current flowing in from the data driving unit (22).

[0136] The voltage compensation unit (50) can perform a sourcing operation in response to the data voltage of the current frame being higher than the data voltage of the previous frame.

[0137] The voltage compensation unit (50) can perform a sinking operation in response to the data voltage of the current frame being lower than the data voltage of the previous frame.

[0138] FIG. 7 is a circuit diagram of a voltage compensation unit of an electrophoretic display device according to one embodiment.

[0139] Referring to FIG. 7, as an example of a simple configuration of the voltage compensation unit (50), the voltage compensation unit (50) may include a digital-to-analog converter (DAC) (51), a voltage adder (52), an operational amplifier (53), and a current amplifier (54).

[0140] The digital-to-analog converter (DAC) (51) receives a digital driving voltage and a compensation voltage, and can convert them into an initially set analog driving voltage (Vref) and an analog compensation voltage (Vcomp), respectively, and output them. The digital driving voltage may be a data voltage supplied to the data driving unit (22) in the initial state or before a state change occurs. The digital compensation voltage may be a voltage supplied under the control of the control unit (30) when compensation of the driving voltage is required. If there is no digital compensation voltage, the digital-to-analog converter (51) can convert only the digital driving voltage and output only the analog driving voltage (Vref).

[0141] As a simple example of a voltage adder (52), the voltage adder (52) is a circuit in which two input voltages (Vref, Vcomp) are connected to the inverting input terminal (-) of an operational amplifier (52a) through respective input resistors (R1, R2), the non-inverting input terminal (+) is grounded through a resistor (RB), and a feedback resistor (RA) is connected between the output terminal and the inverting input terminal (-).

[0142] The voltage adder (52) receives the driving voltage (Vref) and the compensation voltage (Vcomp) from the digital-to-analog converter (51), adds them to generate the compensated voltage (Vref + Vcomp), and can output the compensated voltage (Vref + Vcomp = Vo). For example, if the driving voltage (Vref) is +19V and the driving voltage (Vref) needs to be increased from +19V to +21V, instead of generating a new +21V, the compensated voltage can be generated as +21V by adding +2V to the +19V driving voltage (Vref).

[0143] In various embodiments, the summing of the driving voltage (Vref) and the compensation voltage (Vcomp) can be implemented in various ways instead of using a digital-to-analog converter (51) and a voltage adder (52). For example, it is possible to sum the two voltages using a charge pump. The voltage summing method is not limited to a specific circuit configuration and can be implemented in various forms.

[0144] The positive (+) voltage (VDDp) and negative (-) voltage (VDDn) of the operational amplifier (53) may include a voltage range greater than the variable range of voltage from the voltage adder (52).

[0145] The operational amplifier (53) may include an OP-AMP. A compensated voltage (Vref+Vcomp) input from a voltage adder (52) is supplied to the non-inverting input terminal (+) of the operational amplifier (53), and the voltage of the output node of the current amplifier (54) may be fed back and supplied to the inverting input terminal (-).

[0146] The output terminal of the operational amplifier (53) can be connected to the input node of the current amplifier (54).

[0147] The operational amplifier (53) can supply the sinking current or sourcing current required to drive the current amplifier (54).

[0148] The operational amplifier (53) can output current by comparing the feedback voltage of the non-inverting input terminal (+) and the inverting input terminal (-).

[0149] The current amplifier (54) may include a first switching element (Q1), a second switching element (Q2) connected to the first switching element (Q1), and a resistor (R3) connected to the first switching element (Q1) and the second switching element (Q2).

[0150] The first switching element (Q1) is an NPN transistor as a switching element, and the second switching element (Q2) may be a PNP transistor as a switching element.

[0151] The first switching element (Q1) has its collector connected to a positive (+) voltage (VDDp) and its emitter connected to an output node.

[0152] The second switching element (Q2) has its collector connected to a negative (-) voltage (VDDn) and its emitter connected to an output node.

[0153] One side of the resistor (R3) can be commonly connected to the output terminal of the operational amplifier (53), the base of the first switching element (Q1), and the second switching element (Q2). The other side of the resistor (R3) can be commonly connected to the emitters of the first switching element (Q1) and the second switching element (Q2).

[0154] The current amplifier (54) may include a push-pull amplifier.

[0155] The current amplifier (54) can turn on the upper side first switching element (Q1) and turn off the lower side second switching element (Q2) by the current output from the operational amplifier (53) to the current amplifier (54). Accordingly, the current amplifier (54) can amplify the current output from the operational amplifier (53) and supply it to the data supply unit (22).

[0156] Additionally, the current amplifier (54) can turn off the upper side first switching element (Q1) and turn on the lower side second switching element (Q2) by the incoming current flowing from the data driving unit (22) to the operational amplifier (53). Thus, the current amplifier (54) can absorb the current flowing in from the data driving unit (22).

[0157] A voltage difference can be formed across the resistor (R3) by the current passing through the resistor (R3) of the current amplifier (54). When a voltage difference is formed across the resistor (R3), the base current of the first switching element (Q1) and the second switching element (Q2) is generated or released by this voltage difference, thereby allowing the first switching element (Q1) and the second switching element (Q2) to be selectively turned on or off. The resistance value of the resistor (R3) can be adjusted according to the charge / discharge current of the capacitive load.

[0158] An electrophoretic display device (1) according to one embodiment can compensate for the driving voltage supplied to the data driving unit (22) through a voltage compensation unit (50) having the above configuration when the electrical characteristics of the display panel (10) change. In addition, through the voltage compensation unit (50), it can stably supply a charging current to the data driving unit (22) when charging a capacitive load and stably absorb a discharge current flowing in from the data driving unit (22) when discharging a capacitive load.

[0159] FIG. 8 is a circuit diagram of a stabilization circuit of an electrophoretic display device according to one embodiment.

[0160] Referring to FIG. 8, the stabilization circuit (60) is electrically connected to the common electrode (13) through a common line.

[0161] The stabilization circuit (60) can form a stable potential of the common electrode (13) for the data voltage supplied to the pixel electrode (12).

[0162] The stabilization circuit (60) can stabilize the potential of the common electrode (13) by absorbing the current flowing in from the common electrode (13) or supplying current to the common electrode (13) during the charging and discharging of the capacitive load of the pixel (11), thereby preventing the common voltage (Vcom) from flowing to the pixel electrode (12).

[0163] The stabilization circuit (60) can perform a sinking operation that absorbs current flowing in from the capacitive load when charging the capacitive load, or a sourcing operation that supplies current to the capacitive load when discharging the capacitive load.

[0164] The stabilization circuit (60) can absorb current flowing into the common electrode (13) through a sinking operation when charging the capacitive load. The stabilization circuit (60) can supply current to the common electrode (13) through a sourcing operation when discharging the capacitive load.

[0165] The stabilization circuit (60) can stabilize the potential of the common electrode (13) by performing a sinking operation when charging the capacitive load and automatically performing a sourcing operation when discharging the capacitive load.

[0166] The stabilization circuit (60) can perform a sourcing operation to supply a charging current to the common electrode (13) or a sinking operation to absorb the current flowing in from the common electrode (13) based on the difference between the data voltage of the current frame and the data voltage of the previous frame.

[0167] The stabilization circuit (60) can perform a sinking operation in response to the data voltage of the current frame being higher than the data voltage of the previous frame.

[0168] The stabilization circuit (60) can perform a sourcing operation in response to the data voltage of the current frame being lower than the data voltage of the previous frame.

[0169] The stabilization circuit (60) may include a digital-to-analog converter (DAC) (61), an operational amplifier (62), and a current amplifier (63).

[0170] The digital-to-analog converter (61) can receive a digital common voltage as input and convert it into an analog common voltage (Vcom) to output. The common voltage (Vcom) can be supplied under the control of the control unit (30). The common voltage (Vcom) can be an AC voltage or a DC voltage.

[0171] The operational amplifier (62) can quickly reflect the voltage change of the common electrode (13). For example, the operational amplifier (62) can quickly reflect the voltage change of the common electrode (13) by receiving feedback on the common voltage of the common electrode (13).

[0172] The positive (+) voltage (VDDp) and negative (-) voltage (VDDn) applied to the operational amplifier (62) may include a voltage range greater than the variable range of the common voltage.

[0173] The operational amplifier (62) may include an OP-AMP. A common voltage (Vcom) input to a digital-to-analog converter (DAC) (61) is supplied to the non-inverting input terminal (+) of the operational amplifier (62), and the voltage of the output node of a current amplifier (63) may be fed back and supplied to the inverting input terminal (-).

[0174] The output terminal of the operational amplifier (62) can be connected to the input node of the current amplifier (63).

[0175] The operational amplifier (62) can supply the sinking current or sourcing current required to drive the current amplifier (63).

[0176] The current amplifier (63) may include a third switching element (Q3), a fourth switching element (Q4) connected to the third switching element (Q3), and a resistor (R4) connected to the third switching element (Q3) and the fourth switching element (Q4).

[0177] The third switching element (Q3) is an NPN transistor, and the fourth switching element (Q4) may be a PNP transistor.

[0178] The third switching element (Q3) has its collector connected to a positive (+) voltage (VDDp) and its emitter connected to an output node.

[0179] The fourth switching element (Q4) has its collector connected to a negative (-) voltage (VDDn) and its emitter connected to an output node.

[0180] One side of the resistor (R4) can be commonly connected to the output terminal of the operational amplifier (62), the base of the third switching element (Q3), and the base of the fourth switching element (Q4). The other side of the resistor (R4) can be commonly connected to the emitters of the third switching element (Q3) and the fourth switching element (Q4).

[0181] The current amplifier (63) may include a push-pull amplifier.

[0182] The current amplifier (63) can turn on the upper third switching element (Q3) and turn off the lower fourth switching element (Q4) by the current output from the operational amplifier (62) to the current amplifier (63). Accordingly, the current amplifier (63) can amplify the current output from the operational amplifier (62) and supply it to the common electrode (13).

[0183] Additionally, the current amplifier (63) can turn off the upper side third switching element (Q3) and turn on the lower side fourth switching element (Q4) by the current flowing from the common electrode (13) to the operational amplifier (62). Thus, the current amplifier (63) can absorb the current flowing from the common electrode (13).

[0184] A voltage difference can be formed across the resistor (R4) by the current passing through the resistor (R4) of the current amplifier (63). When a voltage difference is formed across the resistor (R4), the base current of the third switching element (Q3) and the fourth switching element (Q4) is generated or released by this voltage difference, thereby allowing the third switching element (Q3) and the fourth switching element (Q4) to be selectively turned on or off. The resistance value of the resistor (R4) can be adjusted according to the charge / discharge current of the capacitive load.

[0185] An electrophoretic display device (1) according to one embodiment can stably absorb current flowing in from a common electrode (13) during charging of a capacitive load and stably supply current to a common electrode (13) during discharge of a capacitive load through a stabilization circuit (60) having the above configuration.

[0186] FIG. 9 is an example of a flowchart for a control method of an electrophoretic display device according to one embodiment.

[0187] Referring to FIG. 9, the control unit (30) can supply a common voltage to the common electrode (13) through the voltage compensation unit (50) (100).

[0188] The control unit (30) can supply a driving voltage to the data driving unit (22) through the voltage compensation unit (50) (102).

[0189] The control unit (30) can supply a data voltage having a waveform composed of a series of voltage waveforms through the data driving unit (22) to the pixel electrode (12) via the TFT (14) (104).

[0190] The control unit (30) can detect the current and voltage on the power side of the data driving unit (22) through the first sensor unit (70) during the charging and discharging of the capacitive load (106). For example, the control unit (30) can receive the first current data on the power side of the data driving unit (22) detected by the first current sensor (71). The control unit (30) can receive the first voltage data on the power side of the data driving unit (22) detected by the first voltage sensor (72).

[0191] The control unit (30) can accumulate and store first detection data, including first current data and first voltage data detected by the first sensor unit (70), in the memory (31) (108).

[0192] The control unit (30) can detect the current and voltage of the common electrode (13) through the second sensor unit (80) during the charging and discharging of the capacitive load (110). For example, the control unit (30) can receive second current data of the common electrode (13) detected by the second current sensor (81). The control unit (30) can receive second voltage data of the common electrode (13) detected by the second voltage sensor (82).

[0193] The control unit (30) can accumulate and store second detection data, including second current data and second voltage data detected by the second sensor unit (80), in the memory (31) (112). At this time, the control unit (30) can accumulate and store the first detection data and the second detection data in a corresponding manner. In addition, the control unit (30) can accumulate and store the first detection data, the second detection data, and the detected time data in a corresponding manner.

[0194] The control unit (30) can compensate the driving voltage supplied from the voltage compensation unit (50) to the data driving unit (22) so that the first detection data and / or the second detection data reach the preset reference data based on the accumulated first detection data and second detection data. For example, the control unit (30) can identify whether the second detection data corresponding to the first detection data reaches the preset reference data and can actively compensate the driving voltage supplied to the data driving unit (22) repeatedly. For example, when charging a capacitive load, if the driving voltage supplied from the voltage compensation unit (50) to the data driving unit (22) is +15V, and the current waveform of the common electrode (13) differs from the reference current waveform as preset reference data in the initial state or before a state change occurs, the driving voltage supplied from the voltage compensation unit (50) to the data driving unit (22) can be increased from +15V to the preset +17V to compensate for changes in the electrical characteristics of the display panel (10). At this time, additional compensation can be provided by detecting the current change and comparing the initial and previous current waveform states. Accordingly, the current waveform of the common electrode (13) can be matched to the reference current waveform in the initial state or before a state change occurs.

[0195] Accordingly, the electrophoretic display device (1) according to one embodiment can compensate for the voltage supplied to the data driving unit (22) even if the electrical characteristics of the color pigments, solvent, and switching element of the display panel (10) change due to a high / low temperature environment or long-term operation, thereby reducing the sense of unease, afterimage, color change, and increased power consumption caused by changes in electrical characteristics, and can improve long-term lifespan and reliability.

[0196] An electrophoretic display device (1) according to one embodiment can detect changes in electrical characteristics in real time caused by the charging and discharging of a capacitive load and the movement of a charged color pigment.

[0197] However, if the control unit (30) monitors in real time both the total charging and discharging of the capacitive load and the changes in electrical characteristics caused by the movement of the charged color pigment, an excessive load may occur in the system.

[0198] Accordingly, the control unit (30) can periodically collect changes in electrical characteristics caused by the charging and discharging of the capacitive load and the movement of the charged color pigment. For example, the control unit (30) can secure changes in electrical characteristics caused by the charging and discharging of the capacitive load and the movement of the charged color pigment in a short-term cycle or a long-term cycle in units of hours / days / weeks / months / years.

[0199] FIG. 10 illustrates a section for detecting changes in electrical characteristics during charging and discharging of a capacitive load in an electrophoretic display device according to one embodiment.

[0200] Referring to FIG. 10, the entire section is divided into a detection section (200), a reset section (210), and a write section (220). The driving period (210, 220) may include the reset section (210) and the write section (220).

[0201] Even when securing the total current data and voltage data in the reset section (210) and the write section (220), an excessive load may occur on the system.

[0202] Accordingly, a separate detection section (200) can be provided so as not to affect the driving period (210, 220). For example, the detection section can be provided separately in the section prior to the reset section (210) and the writing section (220).

[0203] The control unit (30) can collect current and voltage data during the charging and discharging of a capacitive load in the detection section (200). Accordingly, the driving waveform used in the detection section (200) can be a waveform that best reflects the change in the electrical characteristics of the display panel (10). At this time, it is not limited to a specific voltage or waveform.

[0204] FIG. 11 illustrates compensating the driving voltage supplied to the data driving unit in an electrophoretic display device according to one embodiment.

[0205] Referring to FIG. 11, the control unit (30) can detect at least one of the current and voltage of the common electrode (13) through the second sensor unit (80) (300).

[0206] The control unit (30) can determine whether there is a difference by comparing the current (voltage) of the common electrode (13) with the initial reference current (voltage) (302).

[0207] If there is a difference between the current (voltage) of the common electrode (13) and the reference current (voltage) (302, e.g.), the control unit (30) can compensate the driving voltage supplied from the voltage compensation unit (50) to the data driving unit (22) (304).

[0208] If there is no difference between the current (voltage) of the common electrode (13) and the reference current (voltage) (302, no), the control unit (30) can store the compensation voltage used for the driving voltage in the memory (32) (306).

[0209] The current and voltage set in the initial state of the display panel (10) weaken or accelerate as the characteristics of the display panel change due to the passage of time and electrical stress. The amount of compensation for the driving voltage supplied to the data driving unit (13) can be determined to restore the current and voltage of the common electrode (13) to their initial state. At this time, the amount of current entering the common electrode (13) is continuously detected, and the initial setting value is used as a reference value. For example, when a driving voltage of +15V is supplied to the data driving unit (22), the initial current waveform entering the common electrode (13) is stored, and after a period of time, changes in the time and magnitude of the current waveform are detected. This occurs because changes in the TFT characteristics of the display panel (10) and changes in the charge characteristics of the solvent and pigments result in changes in the movement characteristics of the pigments, causing changes in speed or distance. Similarly, changes in magnitude and time also occur in the current of the common electrode. To restore this to the initial state, the driving voltage is compensated. By sequentially adding +1V, +2V, +3V, etc. to the driving voltage, a value that rises to the most appropriate level is found and this is searched as the optimal compensation value. In addition, if a phenomenon of increased width of the current waveform occurs due to response time delay, additional compensation can be performed by varying the pulse width of the driving voltage. Through this process, the electrical characteristics of the display panel (10) can be maintained similar to the initial state.

[0210] The control unit (30) can predict and apply an appropriate compensation value for a change in the amount of charge generated in a capacitive load using preset waveforms and compensation data.

[0211] The control unit (30) can periodically collect compensation results and perform optimization through additional compensation when necessary.

[0212] The control unit (30) can calculate the amount of change by comparing the n-th previous data ((n-1)th existing data) with the current n-th current data. The amount of change can be compared with a preset panel characteristic lookup table to calculate the degree of change in the electrical characteristics of the display panel (10).

[0213] The control unit (30) may obtain initialization data of the display panel (10) to be evaluated several times or for a certain period, and generate an additional lookup table based on the amount of change. This is because the panel characteristic lookup table is an averaged representative value obtained through large-scale evaluation and may not match the characteristics of each product or unit panel.

[0214] Generally, due to the electrical characteristics of the display panel (10), a process is required to compare and accumulate data over a long period regarding the environment and driving stress. Therefore, instead of storing the entire sampling data, the control unit (30) can store the changed difference value in two dimensions by comparing the (n-1)th-order ... (nk)th-order data with the nth-order data, and track the subsequent change trend using statistical methods. At this time, the sampling data can be quantized by dividing it into defined intervals, converting it into discrete levels, and assigning a representative value to each interval. A new additional lookup table can be created using the quantized values ​​and repeatedly updated through continuous self-evaluation. The control unit (30) can calculate an n+1 prediction value based on the change amount trend, determine a compensation voltage based on the n+1 prediction value, and compensate the driving voltage by applying the compensation voltage to the driving voltage through the voltage compensation unit (50).

[0215] In addition, even if a compensation voltage is applied during the (n+1) period using a compensation voltage table, it may not match the compensation characteristics for each product / unit panel. Therefore, the control unit (30) can obtain the amount of change several times initially or for a certain period after application during the (n+1) period and evaluate whether the compensation voltage is appropriate. In addition, if there is an under- or over-compensation voltage, a new compensation lookup table can be created, and the new compensation lookup table can be used to additionally apply it to the driving section after (n+1).

[0216] The control unit (30) can change the application time or increase / decrease the number of unit pulses based on the final lookup table when the compensation voltage of the lookup table reaches a voltage range that can no longer be supplied by the voltage compensator (50) or when the effect of voltage compensation is insufficient. The time of the driving pulse, the number of pulses, and the duration of the driving interval can be changed. The control unit (30) can compensate for permanent color fading or changes in driving characteristics by increasing or decreasing the width and / or time of the driving unit pulse or increasing / decrease the number of applied unit pulses through Pulse Width Modulation (PWM) control, and can compensate for or reduce the degradation of the characteristics of the display panel (10).

[0217] According to the present disclosure, the long lifespan and reliability of the electrophoretic display device (1) can be improved.

[0218] An electrophoretic display device (1) according to one embodiment comprises: a common electrode (13) to which a common voltage is supplied; a pixel electrode (12) arranged to correspond to the common electrode (13); a plurality of color pigments arranged between the common electrode (13) and the pixel electrode (12) and dispersed in a solvent; a data driving unit (22) for supplying a data voltage to the pixel electrode (12); a voltage compensation unit (50) for compensating the driving voltage supplied to the data driving unit (22); a first sensor unit (70) for detecting first detection data including at least one of the current and voltage on the power side of the data driving unit (22); a second sensor unit (80) for detecting second detection data including at least one of the current and voltage of the common electrode (13); and a memory for accumulating and storing the first detection data and the second detection data in correspondence. and a control unit (30) that controls the voltage compensation unit (50) to bring at least one of the first detection data and the second detection data to a preset reference data based on the first detection data and the second detection data.

[0219] The above voltage compensation unit (50) includes a plurality of voltage compensation units (50), and the plurality of voltage compensation units (50) can supply a driving voltage of a plurality of voltage levels corresponding to a plurality of voltage levels of the data voltage to the data driving unit (22).

[0220] The voltage compensation unit (50) can supply the driving voltage to the data driving unit (22) and perform a sourcing operation to supply current to the data driving unit (22) based on the difference between the data voltage of the current frame and the data voltage of the previous frame, or a sinking operation to absorb current flowing in from the data driving unit (22).

[0221] The above voltage compensation unit (50) includes: a voltage adder that receives the driving voltage and the compensation voltage provided by the control unit (30) as inputs and adds them to generate a compensated voltage; an operational amplifier to which the compensated voltage from the voltage adder is input; and a current amplifier connected to the operational amplifier; wherein the compensated voltage is supplied to a non-inverting input terminal, the voltage of the output node of the current amplifier is fed back to the inverting input terminal, and the output terminal can be connected to the input node of the current amplifier.

[0222] The above current amplifier comprises: a first switching element (Q1); a second switching element (Q2) connected to the first switching element (Q1); and a resistor (R3) connected to the first switching element (Q1) and the second switching element (Q2); wherein the first switching element (Q1) includes an NPN switching element and the second switching element (Q2) includes a PNP switching element, and one side of the resistor (R3) is commonly connected to the output terminal of the operational amplifier and the base of the first switching element (Q1) and the second switching element (Q2), and the other side may be commonly connected to the emitter of the first switching element (Q1) and the second switching element (Q2).

[0223] In response to the voltage difference formed across the resistor (R3) by the current output from the operational amplifier to the data driving unit (22), the first switching element (Q1) can be turned on and the second switching element (Q2) can be turned off to supply current to the data driving unit (22).

[0224] In response to the voltage difference formed across the ends of the resistor (R3) by the current flowing from the data driving unit (22) to the operational amplifier, the first switching element (Q1) can be turned off and the second switching element (Q2) can be turned on to absorb the current flowing from the data driving unit (22).

[0225] The electrophoretic display device (1) may include a stabilization circuit (60) that performs a sourcing operation to supply current to the common electrode (13) or a sinking operation to absorb current flowing in from the common electrode (13) based on the difference between the data voltage of the current frame and the data voltage of the previous frame.

[0226] The above stabilization circuit (60) includes an operational amplifier that receives the common voltage; and a current amplifier connected to the operational amplifier; wherein the operational amplifier is supplied with the common voltage to a non-inverting input terminal, the voltage of the output node of the current amplifier is fed back to the inverting input terminal, and the output terminal can be connected to the input node of the current amplifier.

[0227] The above current amplifier comprises: a third switching element (Q3); a fourth switching element (Q4) connected to the third switching element (Q3); and a resistor (R4) connected to the third switching element (Q3) and the fourth switching element (Q4); wherein the third switching element (Q3) includes an NPN switching element and the fourth switching element (Q4) includes a PNP switching element, and one side of the resistor (R4) is commonly connected to the output terminal of the operational amplifier and the base of the third switching element (Q3) and the fourth switching element (Q4), and the other side may be commonly connected to the emitter of the third switching element (Q3) and the fourth switching element (Q4).

[0228] In response to the voltage difference formed across the ends of the resistor (R4) by the current flowing from the common electrode (13) to the operational amplifier, the third switching element (Q3) can be turned off and the fourth switching element (Q4) can be turned on to absorb the current flowing from the common electrode (13).

[0229] In the above current amplifier, the third switching element (Q3) can be turned on and the fourth switching element (Q4) can be turned off in response to the voltage difference formed across the ends of the resistor (R4) by the current supplied to the common electrode (13) from the operational amplifier to supply current to the common electrode (13).

[0230] The electrophoretic display device (1) further includes a third sensor unit (90) that detects third detection data including at least one of the temperature and humidity of the data driving unit (22), and the control unit (30) can control the voltage compensation unit (50) to bring at least one of the first detection data and the second detection data to the preset reference data based on the first detection data, the second detection data and the third detection data.

[0231] The control unit (30) can compensate the driving voltage through the voltage compensation unit (50) during the power booting stage so as to compensate the driving voltage before the driving section of the electrophoretic display device begins.

[0232] The control unit (30) can detect the first detection data and the second detection data through the first sensor unit (70) and the second sensor unit (80) in a short-term or long-term cycle in units of time / day / week / month / year.

[0233] The control unit (30) can detect the first detection data and the second detection data through the first sensor unit (70) and the second sensor unit (80) in a detection section provided before the driving section of the electrophoretic display device.

[0234] The control unit (30) can control at least one of the application time of the driving voltage, the width of the driving pulse of the driving voltage, and the number of the driving pulses through digital control.

[0235] The control unit (30) can quantize the amount of change by comparing the first detection data and the second detection data detected through the first sensor unit (70) and the second sensor unit (80) with the (n-1)th data and the nth data, store the quantized data in the memory, track the trend of the amount of change based on the quantized data, predict n+1th data based on the trend of the amount of change, determine a compensation voltage to compensate the driving voltage based on the predicted (n+1)th data, and compensate the driving voltage based on the compensation voltage during the (n+1) period.

[0236] A control method for an electrophoretic display device (1) according to one embodiment may include: supplying a common voltage to a common electrode (13); supplying a driving voltage to a data driving unit (22) that supplies a data voltage to a pixel electrode (12); supplying the data voltage to the pixel electrode (12); detecting a first detection data including at least one of a power-side current and voltage of the data driving unit (22); detecting a second detection data including at least one of a current and voltage of the common electrode (13); accumulating and storing the first detection data and the second detection data in a corresponding manner; and compensating the driving voltage supplied to the data driving unit (22) so as to cause at least one of the first detection data and the second detection data to reach a preset reference data based on the first detection data and the second detection data.

[0237] The control method of the electrophoretic display device (1) further comprises detecting a third detection data including at least one of the temperature and humidity of the data driving unit (22); and compensating the driving voltage may include compensating the driving voltage supplied to the data driving unit (22) so as to cause at least one of the first detection data and the second detection data to reach the preset reference data based on the first detection data, the second detection data and the third detection data.

[0238] Meanwhile, the disclosed embodiments may be implemented in the form of a storage medium that stores instructions executable by a computer. The instructions may be stored in the form of program code, and when executed by a processor, they may generate a program module to perform the operation of the disclosed embodiments.

[0239] Computer-readable recording media include all types of recording media that store instructions that can be decoded by a computer. Examples include ROM (read-only memory), RAM (random access memory), magnetic tape, magnetic disk, flash memory, optical data storage devices, etc.

[0240] Additionally, computer-readable recording media may be provided in the form of non-transitory storage media. Here, 'non-transitory storage media' simply means that it is a tangible device and does not contain a signal (e.g., electromagnetic waves), and this term does not distinguish between cases where data is stored semi-permanently and cases where it is stored temporarily. For example, 'non-transitory storage media' may include a buffer in which data is stored temporarily.

[0241] According to one embodiment, the method according to the various embodiments disclosed herein may be provided by being included in a computer program product. The computer program product may be traded between a seller and a buyer as a product. The computer program product may be distributed in the form of a device-readable storage medium (e.g., compact disc read-only memory (CD-ROM)), or distributed online (e.g., download or upload) through an application store (e.g., Play Store™) or directly between two user devices (e.g., smartphones). In the case of online distribution, at least a portion of the computer program product (e.g., downloadable app) may be temporarily stored or temporarily created on a device-readable storage medium, such as the memory of a manufacturer's server, an application store's server, or a relay server.

[0242] As described above, the disclosed embodiments have been explained with reference to the attached drawings. Those skilled in the art will understand that the present invention may be practiced in forms different from the disclosed embodiments without changing the technical spirit or essential features of the invention. The disclosed embodiments are illustrative and should not be interpreted restrictively.

Claims

1. In an electrophoretic display device for displaying images, A common electrode to which a common voltage is supplied; A pixel electrode positioned to correspond to the above common electrode; A plurality of color pigments disposed between the common electrode and the pixel electrode and dispersed in a solvent; A data driving unit that supplies the data voltage of one frame among the data voltages of a plurality of frames of any one of the above images to the pixel electrode; A voltage compensation unit that compensates the driving voltage supplied to the above data driving unit; A first sensor unit that repeatedly detects first detection data including at least one of a first current and a first voltage on the power side of the data driving unit; A second sensor unit that repeatedly detects second detection data including at least one of a second current and a second voltage of the common electrode; A memory that corresponds the repeatedly detected first detection data and the repeatedly detected second detection data to each other and stores them cumulatively as accumulated first detection data and accumulated second detection data; and An electrophoretic display device comprising: a control unit configured to control a voltage compensation unit to compensate the driving voltage supplied to the data driving unit by supplying a compensation voltage based on the accumulated first detection data and the accumulated second detection data, so as to ensure that at least one of the first detection data and the second detection data reaches a set reference data.

2. In Paragraph 1, The above voltage compensation unit is one of a plurality of voltage compensation units, and The above control unit is further configured to control each of the plurality of voltage compensation units to compensate for the driving voltage of each of the plurality of voltage levels of the data voltage supplied to the data driving unit, and An electrophoretic display device configured such that the plurality of voltage compensation units supply a driving voltage of each of the plurality of voltage levels corresponding to the data voltage to the data driving unit.

3. In Paragraph 1, The above voltage compensation unit is, The above driving voltage is supplied to the data driving unit, and An electrophoretic display device configured to perform at least one operation including a sourcing operation of supplying a charging current to a data driver based on the difference between the data voltage of a current frame among the frames and the data voltage of a previous frame among the frames, or a sinking operation of absorbing a discharge current flowing in from the data driver.

4. In Paragraph 1, The above voltage compensation unit is, A voltage adder configured to receive the driving voltage and the compensation voltage, and to add the driving voltage and the compensation voltage to generate a compensated voltage; An operational amplifier configured to receive the compensated voltage from the above voltage adder; and A current amplifier connected to the above operational amplifier; including The above compensated voltage is supplied to the non-inverting input terminal of the operational amplifier, the output voltage of the output node of the current amplifier is fed back to the inverting input terminal of the operational amplifier, and the output terminal of the operational amplifier is connected to the input node of the current amplifier in an electrophoretic display device.

5. In Paragraph 4, The above current amplifier is, A first switching element having a first base and a first emitter; A second switching element having a second base and a second emitter and connected to the first switching element; and A resistor having a first side and a second side, respectively connected to the first switching element and the second switching element; comprising The first switching element above includes an NPN switching element, and The second switching element above includes a PNP switching element, and The first side of the resistor, the first base of the first switching element, and the second base of the second switching element are commonly connected to the output terminal of the operational amplifier, and The second side of the above resistor is an electrophoretic display device that is commonly connected to the first emitter of the first switching element and the second emitter of the second switching element.

6. In Paragraph 5, The above current amplifier is, An electrophoretic display device configured to supply the charging current to the data driving unit by responding to the voltage difference between the first side and the second side of the resistor by the charging current output from the operational amplifier to the data driving unit, wherein the first switching element is turned on and the second switching element is turned off.

7. In Paragraph 5, The above current amplifier is, An electrophoretic display device configured to absorb the discharge current flowing from the data driving unit by responding to a voltage difference formed between the first side and the second side of the resistor by the discharge current flowing from the data driving unit to the operational amplifier, wherein the first switching element is turned off and the second switching element is turned on.

8. In Paragraph 1, An electrophoretic display device comprising a stabilization circuit configured to perform a sourcing operation of supplying a charging current to the common electrode and / or a sinking operation of absorbing a discharge current flowing in from the common electrode based on the difference between the data voltage of the current frame among the frames and the data voltage of the previous frame among the frames.

9. In Paragraph 8, The above stabilization circuit is, An operational amplifier configured to receive the above common voltage; and A current amplifier connected to the above operational amplifier; including An electrophoretic display device in which the above common voltage is supplied to the non-inverting input terminal of the above operational amplifier, the output voltage of the output node of the above current amplifier is fed back to the inverting input terminal of the above operational amplifier, and the output terminal of the above operational amplifier is connected to the input node of the above current amplifier.

10. In Paragraph 9, The above current amplifier is, A third switching element having a third base and a third emitter; A fourth switching element having a fourth base and a fourth emitter and connected to the third switching element; and A resistor having a first side and a second side and connected to the third switching element and the fourth switching element; comprising, The above third switching element includes an NPN switching element, and The above-mentioned fourth switching element includes a PNP switching element, and The first side of the resistor, the third base of the third switching element, and the fourth base of the fourth switching element are commonly connected to the output terminal of the operational amplifier, and The second side of the above resistor is an electrophoretic display device that is commonly connected to the third emitter of the third switching element and the fourth emitter of the fourth switching element.

11. In Paragraph 10, The above current amplifier is, An electrophoretic display device configured to absorb the discharge current flowing from the common electrode by responding to the voltage difference between the first side and the second side of the resistor by the charging current flowing from the common electrode to the operational amplifier, wherein the third switching element is turned off and the fourth switching element is turned on.

12. In Paragraph 10, The above current amplifier is, An electrophoretic display device provided to supply the charging current to the common electrode by responding to the voltage difference between the first side and the second side of the resistor by the charging current supplied to the common electrode in the operational amplifier, wherein the third switching element is turned on and the fourth switching element is turned off.

13. In Paragraph 1, It further includes a third sensor unit that repeatedly detects third sensing data including at least one of the temperature and humidity of the data driving unit, and The above memory is, The above third detection data, which is repeatedly detected, is configured to be stored cumulatively as accumulated detection data, and The above control unit is, An electrophoretic display device configured to control a voltage compensation unit to compensate the driving voltage supplied to the data driving unit by supplying the compensation voltage based on the accumulated first detection data, the accumulated second detection data, and the accumulated third detection data, so that at least one of the first detection data and the second detection data reaches the set reference data.

14. In Paragraph 1, The above control unit is, An electrophoretic display device configured to compensate the driving voltage through the voltage compensation unit during the power boot phase so as to compensate the driving voltage before the driving section of the electrophoretic display device begins.

15. In Paragraph 1, The above control unit is, An electrophoretic display device configured to detect the first detection data and the second detection data in short-term cycles of time / day / week / month / year and / or long-term cycles through the first sensor unit and the second sensor unit.

Images