TWI469121B - Method of operating electrophoretic display - Google Patents

Description

Method of operating an electrophoretic display

The invention relates to an electrophoretic display, in particular to an electrophoretic display which can correctly display a picture after being turned off.

Flat Panel Display is widely used in computer screens, mobile phones, personal digital assistants (PDAs), tablet computers and other electronic products because of its slimness, power saving and no radiation. In recent years, electrophoretic displays have been proposed, and electrophoretic displays, also known as electronic papers, further provide a lighter, more portable display. In general, an electrophoretic display device includes a gate drive circuit, a data drive circuit, a common voltage generator, and a plurality of pixels. The gate drive circuit is used to provide a plurality of gate signals, the data drive circuit is used to provide a plurality of data signals, and the common voltage generator is used to provide a common voltage potential. The electrophoretic display is a bistability display that maintains the original display without power supply. Therefore, the electrophoretic display can turn off the power when the screen does not need to be updated to achieve power saving. However, in the case of the existing electrophoretic display, when the user turns off the power, the gate driving circuit, the data driving circuit, and the common voltage generator are respectively turned off, so that the pixels receive the gate signals and data signals of different levels. And the common voltage potential, thus generating a coupling effect on the pixel and pulling the potential of the pixel high or low, so there is a voltage difference between the potential of the pixel and the common voltage potential. In the case of an electrophoretic display for displaying black and white images, if the potential of the pixel is between the potential and the common voltage potential In the case of a voltage difference, and the potential of the pixel is less than the common voltage potential, the black particles in the electrophoretic display are attracted to be deposited downward, so that the image maintained by the electrophoretic display after being turned off has a black fading phenomenon, that is, The picture will be white.

Please refer to FIG. 1 . FIG. 1 is a timing diagram of a conventional electrophoretic display. The top-down sequence is the timing of the gate signal, the data signal, the common voltage signal, and the pixel potential. In the example of FIG. 1, the electrophoretic display is turned on before time T1, and the waveform of the gate signal is between plus and minus 20 volts (V), and the common voltage signal exhibits a negative level. The level of the pixel potential will vary depending on the level of the gate signal, the data signal, and the common voltage signal. When the user turns off the electrophoretic display at time T1 (for example, pressing the power switch of the electrophoretic display), the common voltage generator first enters the off state at time T2, so the common voltage signal is pulled from the negative level to the ground of 0V. The potential, the potential level of the pixel potential is thus pulled high; then the data driving circuit enters the off state at the time point T3, and no longer transmits the data signal; finally, the gate driving circuit enters the off state at the time point T4, and the gate signal is negative. When 20V is pulled to 0V, the potential of the pixel will gradually be lower than the potential of the common voltage signal, and the voltage difference between the potential of the common voltage signal and the pixel potential will gradually be generated, causing the black particles in the electrophoretic display to deposit downward, so that The screen maintained by the electrophoretic display after shutdown is white.

An embodiment of the present invention is directed to a method of operating an electrophoretic display, the electrophoretic display comprising a switch, a plurality of pixels, a gate driver, a data driver, and a common voltage generator, wherein the pixels are coupled to the gate driver, The data driver and the common voltage product Health device. The method includes turning on the switch, and when the switch is turned on, controlling the gate driver, the data driver, and the common voltage generator to respectively provide a gate signal, a data signal, and a common voltage signal to the pixels to write the data into the gate The pixels are turned off, and the data driver, the gate driver, and the common voltage generator are sequentially turned off when the switch is turned off.

The invention reduces the waveform of the pixel potential and sequentially turns off the data driver, the gate driver and the common voltage generator, so that there is no voltage difference between the potential of the pixel potential and the common voltage signal, so the electrophoresis display is turned off after being turned off. The previous picture can still be displayed normally without the situation where the color becomes dark or faded.

Certain terms are used throughout the description and following claims to refer to particular elements. It should be understood by those of ordinary skill in the art that manufacturers may refer to the same elements by different nouns. The scope of this specification and the subsequent patent application do not use the difference of the names as the means for distinguishing the elements, but the differences in the functions of the elements as the basis for the distinction. The term "including" as used throughout the specification and subsequent claims is an open term and should be interpreted as "including but not limited to". In addition, the term "coupled" is used herein to include any direct and indirect electrical connection. Therefore, if the first device is described as being coupled to the second device, it is meant that the first device can be directly connected to the second device or indirectly connected to the second device through other devices or connection means.

In the following, the electrophoretic display device and the method of operating the same according to the present invention are described in detail with reference to the accompanying drawings, but the embodiments are not intended to limit the scope of the present invention, and the method flow number is not To limit the order of execution, any process that is recombined by method steps, and methods that have equal power are all covered by the present invention.

Please refer to FIG. 2 to FIG. 4 together, FIG. 2 is a schematic diagram of an electrophoretic display 200 according to the present invention, and FIG. 3 is a flow chart of operating the electrophoretic display 200 according to the first embodiment of the present invention, and FIG. 4 is a flowchart A timing diagram of the electrophoretic display 200 is operated in accordance with a first embodiment of the present invention. As shown in FIG. 2, the electrophoretic display 200 includes a switch 270, a plurality of pixels 230, a gate driver 240, a data driver 250, and a common voltage generator 260. The plurality of pixels 230 are coupled to the gate driver 240, the data driver 250, and the common voltage generator 260. The description of FIG. 3 is as follows: Step 302: Turn on the switch 270 at the time point T0; Step 304: After the switch 270 is turned on, the control gate driver 240, the data driver 250, and the common voltage generator 260 respectively provide the gates for the pixels 230. The signal, the data signal and the common voltage signal are used to write the data to the pixel 230. The common voltage signal has a first negative potential N1. Step 306: Turn off the switch 270 at the time point T1; Step 308: Control the total time at the time point T2 The voltage generator 260 outputs a zero potential; step 310: the control data driver 250 outputs the first positive voltage signal S1 at the time point T3, and simultaneously controls the gate driver 240 to output the second positive voltage signal. No. S2, the potential of the first positive voltage signal S1 is lower than the second positive voltage signal S2; Step 312: The control data driver 250 outputs a zero potential at the time point T4, and simultaneously controls the gate driver 240 to output a zero potential; The data driver 250 is turned off in sequence at time T5, the gate driver 240 is turned off at time T6, and the common voltage driver 260 is turned off at time T7; step 316: End.

By controlling the common voltage generator 260 to output a zero potential, the data driver 250 and the gate driver 240 synchronously output the first positive voltage signal S1 and the second positive voltage signal S2, and sequentially turn off the data driver 250 at the time point T5, at the time point. The T6 gate driver 240 and the common voltage driver 260 at the time point T7 can generate a compensation waveform for the pixel potential in the period T2 to T7, so that the pixel potential stably outputs the zero potential after the time point T4, and the data driver 250 is turned off. The mode of the gate driver 240 and the common voltage driver 260 can be as shown in FIG. 4, and the 3.3V data power chip control voltage CON1 is pulled to 0V through the time point T5, and the 3.3V gate power chip is turned on at the time point T6. The control voltage CON2 is pulled to 0V, and the 3.3 V common voltage power chip control voltage CON3 is pulled to 0V at time point T7 to sequentially turn off the data driver 250, the gate driver 240, and the common voltage driver 260. It can be seen from the first embodiment that the waveform of the pixel potential is compensated through steps 302 to 316, so that there is no voltage difference between the potential of the pixel and the potential of the common voltage signal, so that black particles or white particles are not attracted, so After the electrophoretic display 200 is turned off, the screen before the shutdown can still be displayed normally, without A situation in which the color turns black or fades.

Please refer to FIG. 2, FIG. 5 and FIG. 6 together. FIG. 5 is a flowchart of operating the electrophoretic display 200 according to the second embodiment of the present invention, and FIG. 6 is a second embodiment of the present invention. Timing diagram of 200. The description of FIG. 5 is as follows: Step 502: Turn on the switch 270 at the time point T0; Step 504: After the switch 270 is turned on, the control gate driver 240, the data driver 250, and the common voltage generator 260 respectively provide gates for the pixels 230. The pole signal, the data signal and the common voltage signal are used to write the data into the pixels, the common voltage signal has a first negative potential N1; Step 506: Turn off the switch 270 at the time point T1; Step 508: Control the common voltage generator 260 The time T2 outputs a second negative potential N2, and the potential of the second negative potential N2 is higher than the potential of the first negative potential N1; Step 510: The control data driver 250 outputs the first positive voltage signal S1 at the time point T3, and simultaneously controls The gate driver 240 outputs a second positive voltage signal S2. The potential of the first positive voltage signal S1 is lower than the potential of the second positive voltage signal S2. Step 512: Control the data driver 250 to output zero potential at time T4, and simultaneously control The gate driver 240 outputs a third negative potential N3; step 514: turns off the data driver 250 at the time point T5; step 516: turns off the gate driver 240 at the time point T6 to make the gate driver 240 The output of the third negative potential N3 is stopped, and the common voltage generator 260 is simultaneously controlled to output a zero potential; step 518: the common voltage driver 260 is turned off at the time point T7; step 520: end.

The difference between the second embodiment and the first embodiment is that in the second embodiment, different gate signals and common voltage signals are used to generate a compensation waveform for the pixel potentials in the periods T2 to T7. Similarly, the data driver 250, the gate driver 240, and the common voltage driver 260 are sequentially turned off, and the manner of turning off the data driver 250, the gate driver 240, and the common voltage driver 260 can be as shown in FIG. Point T5 pulls 3.3V data power chip control voltage CON1 to 0V, pulls 3.3V gate power chip control voltage CON2 to 0V at time point T6, and 3.3V common voltage power chip control voltage at time point T7 The CON3 is pulled to 0V to sequentially turn off the data driver 250, the gate driver 240, and the common voltage driver 260. It can be seen from the second embodiment that the waveform of the pixel potential is compensated through steps 502 to 520, so that there is no voltage difference between the potential of the pixel and the potential of the common voltage signal, so that black particles or white particles are not attracted, so After the electrophoretic display 200 is turned off, the screen before the shutdown can still be normally displayed without the situation that the color becomes dark or faded.

In summary, the present invention provides a method for operating an electrophoretic display, which compensates for the waveform of the pixel potential and sequentially turns off the data driver 250, the gate driver 240, and the common voltage generator 260 to make the potential of the pixel potential and the common voltage signal There is no voltage difference between them, so after the electrophoretic display 200 is turned off, the screen before the shutdown can still be displayed normally. Show that there is no blackening or lightening of the color.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

200‧‧‧electrophoretic display

230‧‧‧ pixels

240‧‧ ‧ gate driver

250‧‧‧Data Drive

260‧‧‧Common voltage generator

270‧‧‧ switch

302 to 316, 502 to 520 ‧ ‧ steps

N1‧‧‧ first negative potential

N2‧‧‧ second negative potential

N3‧‧‧ third negative potential

S1‧‧‧First positive voltage signal

S2‧‧‧second positive voltage signal

T0 to T7‧‧‧ time

CON1‧‧‧ data power chip control voltage

CON2‧‧‧ gate power chip control voltage

CON3‧‧‧Common voltage power chip control voltage

Figure 1 is a timing diagram of a prior art electrophoretic display.

Figure 2 is a schematic view of an electrophoretic display of the present invention.

Figure 3 is a flow chart showing the operation of the electrophoretic display according to the first embodiment of the present invention.

Fig. 4 is a timing chart showing the operation of the electrophoretic display according to the first embodiment of the present invention.

Fig. 5 is a flow chart showing the operation of the electrophoretic display according to the second embodiment of the present invention.

Fig. 6 is a timing chart for operating an electrophoretic display according to a second embodiment of the present invention.

302 to 316‧‧ steps

Claims (2)

A method for operating an electrophoretic display, the electrophoretic display comprising a switch, a plurality of pixels, a gate driver, a data driver, and a common voltage generator, the pixels being coupled to the gate driver, the data driver, and the a common voltage generator, the method includes: turning on the switch; when the switch is turned on, controlling the gate driver, the data driver, and the common voltage generator respectively to provide gate signals, data signals, and common voltages for the pixels a signal to write data to the pixels; the switch is turned off; when the switch is turned off, the data driver, the gate driver, and the common voltage generator are sequentially turned off; when the switch is turned off, the switch is turned off Before the data driver, controlling the common voltage generator output zero potential; after controlling the common voltage generator output zero potential, and controlling the data driver to output a first positive voltage signal before turning off the data driver; when the data driver When the first positive voltage signal is output, the gate driver is controlled to synchronously output a second positive voltage signal, wherein the first positive voltage The potential of the signal is lower than the second positive voltage signal; when the data driver outputs the first positive voltage signal, and before the data driver is turned off, controlling the data driver output zero potential; and when the data driver outputs zero potential Control the gate driver synchronous output zero Potential. A method for operating an electrophoretic display, the electrophoretic display comprising a switch, a plurality of pixels, a gate driver, a data driver, and a common voltage generator, the pixels being coupled to the gate driver, the data driver, and the a common voltage generator, the method includes: turning on the switch; when the switch is turned on, controlling the gate driver, the data driver, and the common voltage generator respectively to provide gate signals, data signals, and common voltages for the pixels a signal for writing data to the pixels, the common voltage signal having a first negative potential; turning off the switch; and when the switch is turned off, sequentially closing the data driver, the gate driver, and the common voltage generator After the switch is turned off, and before the data driver is turned off, the common voltage generator is controlled to output a second negative potential, the potential of the second negative potential is higher than the first negative potential; when the common voltage is generated After outputting the second negative potential, and controlling the data driver to output a first positive voltage signal before turning off the data driver; when the data driver loses When the first positive voltage signal is controlled, the gate driver synchronously outputs a second positive voltage signal, wherein the potential of the first positive voltage signal is lower than the second positive voltage signal; when the data driver outputs the first positive voltage After the voltage signal, and turn off the data drive Before the actuator, controlling the data driver to output a zero potential; when the data driver outputs a zero potential, controlling the gate driver to synchronously output a third negative potential, wherein when the gate driver is turned off, the gate driver stops outputting The third negative potential; and when the gate driver is turned off, the common voltage generator is controlled to synchronously output a zero potential.