KR20070071487A - Display device of electronic ink type and method for driving the same - Google Patents

Abstract

An electronic ink type display device and a method for driving the same are provided to improve response speed by rapidly driving black and white particles in a micro capsule through a common voltage modulation. An electronic ink type display device includes lower and upper boards(120,110), a common electrode(114), a pixel electrode(160), an electronic ink layer(118), and a driver. The lower board includes plural pixels. The upper board is disposed opposite to the lower board. The common electrode is formed on the upper board. The pixel electrode is formed opposite to the common electrode on the pixel. The electronic ink layer, which is formed on the upper and lower boards, includes micro capsules(118a). The driver applies data voltage to the pixel electrode, applies common voltage which swings at the same amplitude and period as the data voltage and has a symmetrical waveform with the data voltage, to the common electrode, and drives the micro capsules.

Description

Display device of electronic ink type and method for driving the same

1 is a configuration diagram schematically showing a conventional electronic ink display device.

FIG. 2 is a waveform diagram illustrating an example of a common voltage and a data voltage in FIG. 1.

3 is a configuration diagram schematically illustrating an electronic ink display device according to an embodiment of the present invention.

4 is a cross-sectional view illustrating the electronic ink panel of FIG. 2.

5 is a plan view illustrating the lower substrate of FIG. 4.

6 is a waveform diagram illustrating an example of a common voltage and a data voltage in FIG. 3.

7 is a flowchart illustrating a method of driving an electronic ink display device according to an embodiment of the present invention.

(Explanation of symbols for the main parts of the drawing)

100: electronic ink panel 110: upper substrate

114: common electrode 118: electronic ink layer

120: lower substrate 160: pixel electrode

200: drive unit 210: timing controller

220: gate driver 230: data driver

240: common driver GL: gate line

DL: data line TFT: thin film transistor

Sys: System

The present invention relates to an electronic ink display device and a driving method thereof, and more particularly, to an electronic ink display device and a driving method thereof with improved response speed.

Recently, Digital Paper Display (DPD) has been in the spotlight as a next-generation display device following Liquid Crystal Display, Plasma Dilsplay Panel, and Organic Luminescence. As a reflective display device, it is evaluated as an optimal ideal device.

In particular, E-paper (Electric Paper) simulates the form of paper prints made up of a combination of very small ink droplets, and uses a method of effecting ink with twist balls or capsules of 0.1 mm or less in diameter. It is a display device that displays an image, which can be reproduced and used millions of times, and can be driven with very little energy because it does not require backlight or continuous recharging. In addition, electronic paper has a very clear and wide viewing angle, and also has a memory function that does not completely disappear even if there is no power supply, and thus may be widely used in public bulletin boards, advertisements, and e-books.

1 is a configuration diagram schematically showing a conventional electronic ink display device.

The conventional electronic ink type display device has an electronic ink layer 18 formed between the upper substrate 10 and the lower substrate 20 and the two substrates 10 and 20, as shown in FIG.

Transparent electrodes 14 and 16 are formed on one surface of the upper substrate 10 and the lower substrate 20 facing each other, and various microcapsules 18a are dispersed in the electronic ink layer 18.

The microcapsules 18a are composed of a transparent fluid, white particles having positive charges and black particles having negative charges.

When an electric field is applied through the transparent electrodes 14 and 16 of the upper substrate 10 and the lower substrate 20, the charged particles in the microcapsules 18a move to electrodes of opposite signs. That is, while the white particles move to the (-) electrode and the black particles move to the (+) electrode, the observer sees the black particles and the white particles distributed on the transparent electrode 14 side of the upper substrate 10.

In this case, since black particles visually absorb light and white particles visually reflect light, a white image is shown in an area where white particles are distributed, and a black image is shown in an area where black particles are distributed. . In this way, different gray levels may be displayed by appropriately driving the black and white images.

Such a display device using the electronic ink layer 18 can implement a flexible display and has an advantage of extremely small power consumption, but has a disadvantage in that a response speed is slower than that of a liquid crystal.

FIG. 2 is a waveform diagram illustrating an example of a common voltage and a data voltage in FIG. 1, and illustrates a data voltage and a common voltage Vcom when converting from a black level to a white level.

The white and black particles in the microcapsule 18a are applied to the common voltage Vcom applied to the transparent electrode 14 of the upper substrate 10 and the data voltage applied to the transparent electrode 16 of the lower substrate 12. The gray levels are expressed in such a manner as to move according to the voltage and to adjust the time when the voltage is applied.

In the conventional electronic ink type display device, a driver integrated circuit applying a data voltage has a constant output voltage of + 15V to -15V based on the common voltage Vcom as shown in FIG. 2. It is applied during (t) to move the black and white particles and express the gray level through a certain sequence.

In this case, one frame is driven at 20 ms and 50 Hz, and a time for applying voltage due to a slow response speed should be maintained at about 8 frames, and the gray level is different from the initial gray level due to the characteristics of the electronic ink layer 18. It is common to go through a sequence of mixing black and white particles.

However, in order to improve the response speed of the electronic ink layer 18 in this manner, when the driver integrated circuit is designed by converting the high voltage, there is a problem that the cost is greatly increased and the power consumption is increased.

Accordingly, the technical problem to be achieved by the present invention is to efficiently control the electronic ink layer and to apply a high voltage to the electronic ink layer through common voltage modulation so that the black and white particles in the microcapsule move more quickly, thereby increasing the cost or power consumption. It is an object of the present invention to provide an electronic ink display device capable of improving response speed without increasing.

Another object of the present invention is to provide a method of driving an electronic ink display device capable of efficiently driving such an electronic ink display device.

Technical problems to be achieved by the present invention are not limited to the above-mentioned technical problems, and other technical problems not mentioned above will be clearly understood by those skilled in the art from the following description. Could be.

According to another aspect of the present invention, there is provided an electronic ink display device including a lower substrate formed of a plurality of pixels, an upper substrate disposed to face the lower substrate, and formed on one surface of the upper substrate. A common electrode, a pixel electrode formed to face the common electrode on the pixel on the lower substrate, microcapsules uniformly dispersed, and an electronic ink layer formed on the upper substrate and the lower substrate; The electronic ink layer is applied with a data voltage having a constant amplitude and period to the pixel electrode, and a common voltage having a waveform symmetrical with the data voltage and swinging at the same amplitude and period as the data voltage to the common electrode. It characterized in that it comprises a drive for driving the microcapsules of.

The microcapsule consists of a transparent fluid in the form of a ball, black particles with positive charge and white particles with negative charge.

The driving unit is configured to determine the gray level of the pixel based on the intensity of the data voltage, the application time of the data voltage, the intensity of the common voltage, and the application time of the common voltage.

The data voltage and the common voltage may be configured such that an amplitude is greater than or equal to -15V and less than or equal to 15V.

The pixel is formed to intersect with each other and is formed on a gate line and a data line that divides the area of each pixel, and is formed at an intersection of the gate line and the data line, and includes a gate electrode, a semiconductor layer, a source and a drain electrode. And a pixel electrode connected to the drain electrode of the thin film transistor.

The method of driving an electronic ink display device according to an embodiment of the present invention outputs a data control signal and a gate control signal, and determines the period and amplitude of the common voltage according to the vertical and horizontal synchronization signals and the main clock applied from the outside. Outputting a swing control signal, sequentially outputting scan pulses to gate lines of the electronic ink panel according to the gate control signal, and pixels on data lines of the electronic ink panel according to the data control signal Outputting a data voltage of a unit; outputting a common voltage synchronized with the data voltage of a pixel unit according to the swing control signal; and according to a difference voltage between the data voltage and the common voltage in the electronic ink panel. Microcapsules displaying a constant gray level in pixels The data voltage and the common voltage may be output in a symmetrical waveform with the same amplitude and period.

The gray level of the pixel unit is determined by the intensity of the data voltage, the application time of the data voltage, the intensity of the common voltage, and the application time of the common voltage.

The data voltage and the common voltage may be configured such that an amplitude is greater than or equal to -15V and less than or equal to 15V.

Specific details of other embodiments are included in the detailed description and the drawings. Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. Like reference numerals refer to like elements throughout.

Hereinafter, an electronic ink display device and a driving method thereof according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

3 is a configuration diagram schematically illustrating an electronic ink display device according to an embodiment of the present invention.

Referring to FIG. 3, an electronic ink display device according to an embodiment of the present invention is divided into an electronic ink panel 100 displaying an image and a driver 200 driving the electronic ink panel 100.

The electronic ink panel 100 has m gate lines GL1, GL2, GL3,..., GLm and n data lines DL1, DL2, DL3,..., DLn intersected in a matrix to form a plurality of pixels. To distinguish between them. In the following description, when no distinction is required, each of the m gate lines GL1, GL2, GL3,..., GLm and the n data lines DL1, DL2, DL3,..., DLn are respectively divided into gate lines GL. And data line DL.

Each pixel includes a thin film transistor, a storage capacitor, and the like, and the electronic ink panel 100 is formed by a data voltage and a common voltage supplied for each pixel according to a switching operation of the thin film transistor connected to the gate line GL and the data line DL. An image is displayed on the image, and the gray scale display is stabilized as the voltage holding characteristic of the pixel is improved by the storage capacitor.

The driver 200 is configured to include a timing controller 210, a gate driver 220, a data driver 230, a common driver 240, and the like.

The timing controller 210 receives a horizontal control signal (Hsync), a vertical synchronization signal (Vsync), a data enable signal (DE), a main clock (MCLK), etc., supplied from an external system Sys, and a gate control signal. And generate a data control signal and supply the generated control signals to the gate driver 220 and the data driver 230, respectively. The pixel data input from the system Sys is rearranged and supplied to the data driver 230.

The gate control signal includes a gate start pulse (GSP), a gate shift clock (GSC), a gate output enable (GOE), and the data control signal as a source start. A source start pulse (SSP), a source shift clock (SSC), a source output enable (SOC), a polarity inversion signal (POL), and the like are included.

The gate driver 220 sequentially outputs scan pulses to the gate lines GL according to the gate control signal.

The data driver 230 converts the pixel data realigned and supplied from the timing controller 210 into a data voltage and outputs the data voltage to the data lines every one horizontal period according to the data control signal.

The common driver 240 is synchronized with a waveform that is symmetrical with the data voltage, generates a common voltage swinging with a constant amplitude and period, and applies it to the electronic ink panel 100.

4 is a cross-sectional view illustrating the electronic ink panel of FIG. 2.

The electronic ink panel 100 is largely composed of an electronic ink layer 118 formed between the upper substrate 110 and the lower substrate 120, the upper substrate 110, and the lower substrate 120.

The common electrode 114 is formed on the rear surface of the upper substrate 110, and the pixel electrode 160 is formed on the lower substrate 120 in units of pixels. The common electrode 114 and the pixel electrode 160 are made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO), and are connected to the driving unit 200 to have common voltages and data having different polarities. Each voltage is supplied.

The electronic ink layer 118 is a plurality of microcapsules 118a uniformly dispersed in a matrix form a layer (mono-layer). In this case, one pixel may be defined for each predetermined number of microcapsules 118a.

The microcapsule 118a is composed of a ball-shaped transparent fluid 122, positively charged black particles 124, and negatively charged white particles 126.

The common voltage swinging to have a polarity opposite to the data voltage is applied to the common electrode 114 on the upper substrate 110, and the data voltage is applied on the lower substrate 120 according to the switching operation of the thin film transistor TFT. It is applied to the pixel electrode 160 to drive the microcapsules 118a in the electronic ink layer 118.

When an electric field is applied to the upper common electrode 114 and the lower pixel electrode 160 in the electronic ink type display device as shown in FIG. 4, the charged particles in the microcapsule 118a move to the electrode having the opposite polarity. do. That is, in FIG. 4, the white particles 126 move to the electrode having the (+) polarity, and the black particles 124 move to the electrode having the (−) polarity.

The electronic ink panel 100 further includes an adhesive layer on the pixel electrode 160 or a binder filled in the space between the microcapsules 118a.

FIG. 5 is a plan view illustrating the lower substrate of FIG. 4 and illustrates some pixels of FIG. 4.

As illustrated in FIG. 2, the lower substrate 120 includes a plurality of pixels in which regions are defined by gate lines GL and data lines DL that are orthogonal to each other, and the gate line GL and the data line ( Source electrodes 132 facing each other with a gate electrode 131 extending from the gate line GL, a semiconductor layer (not shown), and a semiconductor layer (not shown) interposed between the DLs. ) And a drain electrode 133 are formed to form a thin film transistor (TFT).

The gate voltage of the scan pulse is applied to the gate electrode 131 of the thin film transistor TFT, the data voltage is applied to the source and drain electrodes 132 and 133, and a channel is formed on the semiconductor layer (not shown). The voltage on / off is controlled by the difference voltage between the gate voltage and the data voltage.

6 is a waveform diagram illustrating an example of a common voltage and a data voltage in FIG. 3.

In order for the black and white particles 124 and 126 in the microcapsule 118a constituting the electronic ink layer 118 to express a constant gray level in the form of an impulse, a predetermined voltage may be applied for a predetermined time as shown in Equation 1 below. (dt) should be authorized. At this time, in order to shorten the voltage application time, a high voltage should be applied, but since the driver integrated circuit used as the data driver 230 is designed to be rated, it is possible to increase the output of the data driver 230 without increasing the output of + 15V to -15V. In order to speed up the reaction speed of the electronic ink layer 118 while maintaining a constant level of, as shown in FIG. 6, the common voltage Vcom is applied by swinging.

As shown in FIG. 6, when the common voltage Vcom is swinged within a range of −15 V to 15 V, the reaction speed of the electronic ink layer 118 is increased as compared with the case of FIG. 2 without increasing the output of the data driver 230. You can double the response speed in half.

Due to the characteristics of the electronic ink layer 118, the voltage application time t ＇for expressing a constant gray level is inversely proportional to the intensity of the applied voltage. Therefore, if the applied voltage is doubled, the required voltage application time is halved. To shrink.

As such, by modulating the common voltage, a high voltage can be applied to the electronic ink panel 100 without increasing the output of the data driver 230 for outputting the data voltage or redesigning the corresponding part. The response speed of the electronic ink layer 118 can be improved efficiently.

7 is a flowchart illustrating a method of driving an electronic ink display device according to an embodiment of the present invention.

First, in step S100, the timing controller 210 outputs a data control signal and a gate control signal, and the horizontal synchronization signal Hsync, the vertical synchronization signal Vsync, and the data enable signal applied from an external system Sys. A swing control signal for determining the period and amplitude of the common voltage is output according to the DE and the main clock MCLK.

Next, in step S110, the gate driver 220 sequentially outputs scan pulses to the gate lines GL of the electronic ink panel 100 according to the gate control signal.

Next, in step S120, the data driver 230 outputs a data voltage in pixel units to the data lines DL of the electronic ink panel 100 according to the data control signal.

Next, in operation S130, the common driver 240 outputs a common voltage synchronized with the data voltage in units of pixels according to the swing control signal.

In this case, the data voltage and the common voltage are output in the same amplitude, period, and polarity opposite to each other, and are symmetrical to each other. Can be determined.

Next, in operation S140, the microcapsules 118a on the electronic ink layer 118 are fixed on a pixel-by-pixel basis according to the difference voltage between the two voltages while the data voltage and the common voltage of opposite polarities are applied to the electronic ink panel 100. The gray level will be displayed.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that.

Therefore, since the embodiments described above are provided to completely inform the scope of the invention to those skilled in the art, it should be understood that they are exemplary in all respects and not limited. The invention is only defined by the scope of the claims.

The electronic ink display device according to the preferred embodiment of the present invention made as described above efficiently controls the electronic ink layer, and applies a high voltage to the electronic ink layer through common voltage modulation, so that the black and white particles in the microcapsule are faster. By moving, the response speed can be improved without a significant increase in cost or power consumption.

The driving method of the electronic ink display device according to the preferred embodiment of the present invention can efficiently drive such a display device.

Claims (8)

A lower substrate composed of a plurality of pixels, and an upper substrate disposed to face the lower substrate; A common electrode formed on one surface of the upper substrate; A pixel electrode formed to face the common electrode on the pixel on the lower substrate; An electronic ink layer comprising microcapsules uniformly dispersed and formed on the upper substrate and the lower substrate; And The electronic ink is applied to the pixel electrode by applying a data voltage having a constant amplitude and period, and applying a common voltage having a waveform symmetrical with the data voltage to the common electrode and swinging at the same amplitude and period as the data voltage. And a driver for driving the microcapsules of the layer. The method of claim 1, The microcapsules, An electronic ink type display device comprising a transparent fluid in the form of a ball, black particles having a positive charge, and white particles having a negative charge. The method of claim 1, The driving unit, And the gray level of the pixel is determined by the intensity of the data voltage, the application time of the data voltage, the intensity of the common voltage and the application time of the common voltage. The method of claim 1, The data voltage and the common voltage are An electronic ink display device characterized in that the amplitude is -15V or more and 15V or less. The method of claim 1, The pixel is, A gate line and a data line arranged to cross each other to divide a region of each pixel; A thin film transistor formed at an intersection of the gate line and the data line, the thin film transistor including a gate electrode, a semiconductor layer, a source and a drain electrode; And And a pixel electrode connected to the drain electrode of the thin film transistor. Outputting a data control signal and a gate control signal, and outputting a swing control signal for determining a period and amplitude of a common voltage according to vertical and horizontal synchronization signals and a main clock applied from the outside; Sequentially outputting scan pulses to gate lines of an electronic ink panel according to the gate control signal; Outputting a data voltage in pixels to data lines of the electronic ink panel according to the data control signal; Outputting a common voltage synchronized with the data voltage in pixel units according to the swing control signal; And Displaying the microcapsules in the electronic ink panel displaying a constant gray level in units of pixels according to the difference voltage between the data voltage and the common voltage, And the data voltage and the common voltage are output as waveforms symmetrical with each other with the same amplitude and period. The method of claim 6, And a gray level in units of pixels is determined by the intensity of the data voltage, the application time of the data voltage, the intensity of the common voltage, and the application time of the common voltage. The method of claim 6, The data voltage and the common voltage are A driving method of an electronic ink display device, wherein the amplitude is -15V or more and 15V or less.

Images