KR20130065333A - Electrophoresis display apparatus and method for driving the same - Google Patents

Abstract

The present invention relates to an electrophoretic display device and a driving method thereof capable of reducing power consumption according to image data update.
Electrophoretic display device according to an embodiment of the present invention comprises a display panel for displaying an image using electrophoresis; A controller configured to generate and output a power control signal for controlling generation of a driving voltage used when updating image data for switching from the previous screen to the next screen; And a power supply unit generating only a driving voltage necessary for a white reset period, a black reset period, and a data update period, based on the power control signal, when updating the image data, and updating the image data using the driving voltage generated by the power supply unit. Characterized in that.

Description

Electrophoretic display device and its driving method {ELECTROPHORESIS DISPLAY APPARATUS AND METHOD FOR DRIVING THE SAME}

The present invention relates to an electrophoretic display device, and more particularly, to an electrophoretic display device and a driving method thereof capable of reducing power consumption due to image data update.

The electrophoretic display device refers to a device for displaying an image using an electrophoresis phenomenon in which colored charged particles move by an electric field applied from the outside. Here, the electrophoretic phenomenon refers to a phenomenon in which the charged particles move in the solvent by the Coulomb force when an electric field is applied while the charged particles are dispersed in the solvent.

The electrophoretic display apparatus using the electrophoretic phenomenon has a feature of bistable, and even if the applied voltage is removed, the displayed image can be displayed for a long time. That is, the electrophoretic display device is a display device suitable for the field of e-books that do not require a rapid exchange of the screen because it can maintain a constant screen for a long time even without applying a voltage continuously.

In addition, unlike the liquid crystal display device, the electrophoretic display device does not have a dependency on a viewing angle, and displays an image by reflecting external light, thereby providing a comfortable image to the eye as much as paper.

The electrophoretic display device according to the prior art includes a display panel and a driving circuit unit for driving the display panel. The driving circuit unit includes a data drive IC (data D-IC), a gate drive IC (Gate D-IC), a controller, and a power supply unit.

The display panel includes a lower substrate having a thin film transistor (TFT) and a pixel electrode formed in a matrix form, an upper substrate having a common electrode formed thereon, and an electrophoretic film interposed between the lower substrate and the upper substrate.

The gate drive IC generates a scan pulse that swings between the gate high voltage VGH and the gate low voltage VGL and sequentially supplies the scan pulses to the gate lines formed in the display panel.

The data drive IC generates a data voltage according to the image data and supplies the data voltage to the data lines formed in the display panel. The data voltage is generated as a positive voltage or a negative voltage according to the gray level of the image data. The data voltage supplied to the data line is applied to the pixel electrode via the TFT.

1 and 2 are views showing a method of driving an electrophoretic display device according to the prior art.

1 and 2, a data voltage of −15 V (VNEG) or +15 V (VPOS) is supplied to a pixel electrode formed on a lower substrate. In this case, a common voltage Vcom of −1.4 V to +1.1 V is supplied to the common electrode formed on the upper substrate, and an electric field is formed between the pixel electrode and the common electrode.

The electrophoretic display device can not display a frame on a frame-by-frame basis, such as an LCD, because the screen switching is not fast due to the bi-stability characteristic. Therefore, the image is displayed by supplying a data voltage using a wave form, which is a sequence of image data, and the image is switched from the previous screen to the next screen.

Here, after new image data is written to the pixels through an image (data) update process for a time of about 1 second, the current data is maintained until the next data update to maintain the displayed image for a long time.

When switching the screen by updating the image data, it is necessary to initialize the charged particles through the refresh because the afterimage of the previous screen may remain on the next screen due to the bistable characteristics.

During the white reset period and the black reset period, 15V and -15V voltages are supplied to the pixels to initialize the charged particles in the white and black states. After that, the image of the next screen is updated to the pixel to display the gray of the next screen.

The electrophoretic display device according to the related art, which is driven as described above, is slower than other display devices, and is driven by adjusting a pulse width of a high voltage (PWM method), so that power consumption is large during an update operation for screen switching. There is this.

In particular, only -15V voltage is used in the white reset period and + 15V voltage is used in the black reset period, but the power supply generates both -15V and +15 voltages during the entire reset period and supplies the data drive IC to the update operation. There is a problem that unnecessary power is consumed. In other words, the power supply increases the power consumption by generating both -15V and + 15V voltages from the data start point to the end point and supplying them to the data drive IC.

Since electrophoretic display devices are made of small devices and portable mobile devices, power consumption becomes an important factor for product performance and competitiveness. Accordingly, there is a need for an electrophoretic display device and a driving method thereof capable of reducing power consumption due to image data update.

Disclosure of Invention The present invention has been made in view of the above-described problems, and it is an object of the present invention to provide an electrophoretic display device and a driving method thereof capable of reducing power consumption according to an update of an image.

Other features and advantages of the invention will be set forth in the description which follows, or may be obvious to those skilled in the art from the description and the claims.

Electrophoretic display device according to an embodiment of the present invention comprises a display panel for displaying an image using electrophoresis; A controller configured to generate and output a power control signal for controlling generation of a driving voltage used when updating image data for switching from the previous screen to the next screen; And a power supply unit generating only a driving voltage necessary for a white reset period, a black reset period, and a data update period, based on the power control signal, when updating the image data, and updating the image data using the driving voltage generated by the power supply unit. Characterized in that.

According to an aspect of the present invention, there is provided a method of driving an electrophoretic display device, including: generating, by a controller, a power control signal for controlling generation of a driving voltage used when updating image data for switching from a previous screen to a next screen; Generating only a driving voltage necessary for a white reset period, a black reset period, and a data update period based on the power control signal at the power supply unit; And updating the image data by using the driving voltage generated by the power supply unit.

An electrophoretic display device and a driving method thereof according to an embodiment of the present invention can reduce power consumption according to an image update.

According to an embodiment of the present invention, when the electrophoretic display device is manufactured as a mobile device, the operation time may be extended to provide a user with convenience of portability.

Other features and effects of the present invention may be newly understood through the embodiments of the present invention in addition to the features and effects of the present invention mentioned above.

1 and 2 are views showing a driving method of an electrophoretic display device according to the related art.
3 is a view showing an electrophoretic display device according to an embodiment of the present invention.
4 and 5 are views showing a power supply unit and a driving method thereof of the electrophoretic display device according to an embodiment of the present invention.
6 is a diagram illustrating an output voltage by a power control signal PCS supplied from a control unit to a power supply unit.
7 is a view showing a driving method and an effect of reducing power consumption of an electrophoretic display device according to an exemplary embodiment of the present invention.

Hereinafter, an electrophoretic display device and a driving method thereof according to an embodiment of the present invention will be described with reference to the accompanying drawings. Like reference numerals throughout the specification denote substantially identical components. In the following description, detailed descriptions of configurations and functions that are not related to the core configuration of the present invention and known in the art may be omitted.

3 is a view showing an electrophoretic display device according to an embodiment of the present invention.

Referring to FIG. 3, an electrophoretic display apparatus according to an exemplary embodiment of the present invention may include a display panel 100 and a gate drive IC 200; Data drive IC 300; The controller 400 includes a controller and a power supply unit 500.

The display panel 100 includes a lower substrate, an upper substrate, and an electrophoretic layer. The electrophoretic layer may be formed into a film type including a microcapsule, a micro cup type or an internalization type in which the electrophoretic particles and the solvent are internalized on the lower substrate. In the electrophoretic display device according to the embodiment of the present invention, any type of electrophoretic layer may be applied without limitation to the type of the electrophoretic layer.

In the lower substrate of the display panel 100, m gate lines and n data lines cross each other. By the intersection of the data lines and the gate lines, m × n pixels (Cells) are formed in a matrix form. In each pixel, a TFT is formed as a switching element, and a pixel electrode for supplying a data voltage to the pixel is formed.

The TFT switches the supply of image data (data voltage) to the pixels. The gate electrode of the TFT is connected with the gate line, the source electrode is connected with the data line, and the drain electrode is connected with the pixel electrode.

In addition, the upper substrate of the display panel 100 includes a common electrode for supplying a common voltage Vcom, and an electrophoretic layer is formed between the pixel electrode and the common electrode.

The controller 400 generates a gate control signal for controlling the gate drive IC 200 using the timing signal TS input from the outside, and supplies the gate signal to the gate drive IC 200. In addition, the controller 400 generates a data control signal for controlling the data drive IC 300 and supplies it to the data drive IC 300.

Here, the timing signal TS includes a vertical synchronization signal V-sync, a horizontal synchronization signal H-sync, and a clock signal CLK.

In addition, the controller 400 arranges the image data input from the outside or the image data stored in the memory provided therein in units of frames and supplies the image data to the data drive IC 300.

In addition, the controller 400 generates and supplies a power control signal (PCS) to control the driving of the power supply unit 500 to reduce power consumption during the update period of the image and supplies it to the power supply unit 500. A detailed description of the power control signal PCS will be described later with reference to FIGS. 4 to 6.

The gate drive IC 200 sequentially generates a scan pulse and sequentially supplies the gate lines to the gate lines formed in the display panel 100.

In detail, the gate drive IC 200 generates a scan pulse based on the gate control signal supplied from the controller 400 and the gate driving voltage V2 supplied from the power supply 500. The generated scan pulse is sequentially supplied from the first gate line to the last gate line of the display panel 100.

Here, the gate driving voltage V2 is supplied to the gate drive IC 300 as a gate high voltage VGH having a positive polarity (+) and a gate low voltage VGL having a negative polarity (−), and is provided with a positive polarity (+). The gate high voltage VGH and the gate low voltage VGL of negative polarity are converted into pulsed scan pulses and supplied to the gate lines.

The data drive IC 300 converts the waveform into a data voltage based on the data control signal and the data driving voltage V1 supplied from the controller 400. The data voltage of one horizontal line is supplied to the data lines in accordance with the timing at which the scan pulse is supplied to the gate lines. Here, the data composition voltage V1 may include VPOS, VNEG, and VSS voltages.

The data drive IC 300 selects one of the three-phase voltages VPOS, VNEG, and VSS as the data voltage in response to the digital data input from the controller 400 in the process of updating the image data. The selected data voltage is output to the data lines. The output voltages VPOS, VNEG, and VSS of the data drive IC 300 are supplied to the pixel electrodes of the pixels via the data lines and the TFTs.

The data voltage is supplied to the pixel electrode of the pixel which is turned on by the scan pulse, and an electric field is formed on the pixel by the data voltage supplied to the pixel electrode and the common voltage Vcom supplied to the common electrode, thereby providing the electrophoretic layer. Electrophoresis of the charged particles is made.

4 and 5 are views illustrating a power supply unit and a driving method thereof of an electrophoretic display device according to an exemplary embodiment of the present invention.

4 and 5, when the power of the electrophoretic display is turned on, the power supply unit 500 uses the input power Vin through a DC-DC converter according to a preset power on sequence. As a result, driving voltages VCC, VSS, Vcom, VPOS, VNEG, VGH, and VGL required for driving the display panel 100 are generated.

The generated driving voltages VCC, VSS, Vcom, VPOS, VNEG, VGH, and VGL are selectively supplied to the data drive IC 300, the gate drive IC 300, and the controller 400. In this case, the power-on sequence may be preset in the controller 400 or an external host system.

The driving method of the power supply unit 500 will be described in detail. When the input power Vin is applied to the power supply unit 500, the power supply unit 500 drives in response to the enable signals input from the control unit 400 or the host system. Generate voltages VCC, VSS, Vcom, VPOS, VNEG, VGH, VGL.

In this case, the power supply unit 500 generates the VPOS voltage as the positive data voltage and VNEG as the negative data voltage based on the power control signal PCS supplied from the control unit 400. In this case, the VPOS voltage may be generated as a DC voltage of + 15V, and the VNEG voltage may be generated as a DC voltage of -15V. The VPOS voltage and the VNEG voltage generated by the power supply unit 500 are supplied to the data drive IC 300.

5 and 6, the power control signal PCS may be generated by the controller 400 as a pulse having 2 bits of information and supplied to the power supply 500.

When the power supply control signal PCS has a 2-bit '00' value, the power supply unit 500 generates a base voltage VSS or GND, and generates the generated base voltage VSS or GND. 300).

When the power supply control signal PCS has a value of '01', the power supply unit 500 generates a VPOS voltage of +15 V and supplies the generated VPOS voltage to the data drive IC 300.

Subsequently, when the power supply control signal PCS has a value of '10', the power supply unit 500 generates a VNEG voltage of −15 V and supplies the generated VNEG voltage to the data drive IC 300.

When the power supply control signal PCS has a value of '11', the power supply unit 500 generates a VPOS voltage of + 15V and a VNEG voltage of -15V, and generates the generated VPOS voltage and the VNEG voltage in the data drive IC 300. Supplies).

In this case, the VNEG voltage of -15V may be used as a reset voltage for resetting the charged particles in the white reset period, and the VPOS voltage of + 15V may be used as a reset voltage for resetting the charged particles in the black reset period. .

The logic power supply voltage VCC may be logic required to drive an application specific integrated circuit (ASIC) of the controller 400, a source drive integrated circuit (IC) of the data drive IC 300, and a gate drive IC of the gate drive IC 300. As a voltage, it is generally generated at a DC voltage of 3.3V.

The common voltage Vcom supplied to the common electrode is generated as a DC voltage of -1.4V to + 1.1V.

The negative gate voltage VGL is generated with a DC voltage of -20V to -22V, and the positive gate voltage VGH is generated with a DC voltage of + 20V to + 22V and supplied to the gate drive IC 200.

On the other hand, the VPOS, VNEG, VGH, and VGL voltages are discharged to the GND in the display panel 100 immediately after updating of the image data so that the screen can be stably displayed.

7 is a view showing a driving method and an effect of reducing power consumption of an electrophoretic display device according to an exemplary embodiment of the present invention.

Hereinafter, a method of driving an electrophoretic display device according to an exemplary embodiment of the present invention will be described with reference to FIG. 7.

When the image is updated from the previous screen to the next screen, the controller 400 forms a waveform for screen switching by using the digital image data, and supplies the waveform to the data drive IC 300 together with the data control signal. The gate control signal is also supplied to the gate drive IC 200.

In addition, the controller 400 generates a power control signal PCS based on the waveform, and supplies the generated power control signal PCS to the power supply unit 500.

The power supply unit 500 generates a VNEG necessary for driving white reset in the white reset period based on the power control signal PCS, and supplies the VNEG to the data drive IC 300.

In the black reset period, a VPOS required for black reset driving is generated and supplied to the data drive IC 300.

In addition, during the data update period, at least one of a VPOS and a VNEG that can be used for data update is generated and supplied to the data drive IC 200.

Here, when only the VPOS is required in the data update period after the reset period, the power supply unit 500 generates only the VPOS in the data update period and supplies it to the data drive IC 300.

On the other hand, when only the VNEG is needed in the data update period after the reset period, the power supply unit 500 generates only the VNEG in the data update period and supplies it to the data drive IC 300.

Of course, in the data update period after the reset period, when both the VPOS and the VNEG are required, both the VPOS and the VNEG are generated and supplied to the data drive IC 300.

The gate driver IC 200 generates a scan pulse based on the gate control signal input from the controller 400, and sequentially supplies the generated scan pulse to the gate line to turn on the pixels.

When updating the image data, the data drive IC 300 selects one of the three-phase voltages VPOS, VNEG, and VSS supplied from the power supply unit 500 as a data voltage and outputs the data voltages to the data lines. In this case, the data voltage may be generated as a positive data voltage, a negative data voltage, or a ground voltage VSS.

As described above, the electrophoretic display device and its driving method according to the embodiment of the present invention may be applied to a white reset period, a black reset period, and a data update period in the power supply unit 500 when the image data is updated for switching from the previous screen to the next screen. Only necessary voltages can be generated to perform image data updates.

Through this, the power consumption according to the update of the image data can be reduced. In addition, when the electrophoretic display device is manufactured as a mobile device, an operating time of the device can be extended.

It will be understood by those skilled in the art that the present invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

100: display panel 200: gate drive IC
300: data drive IC 400: control unit
500:

Claims (10)

A display panel displaying an image using electrophoresis;
A controller configured to generate and output a power control signal for controlling generation of a driving voltage used when updating image data for switching from the previous screen to the next screen; And
And a power supply unit generating only a driving voltage necessary for a white reset period, a black reset period, and a data update period, based on the power control signal when updating image data.
The electrophoretic display device, characterized in that for updating the image data by using the driving voltage generated by the power supply. The method according to claim 1,
The power supply unit generates a negative voltage (VNEG) in the white reset period based on the power control signal, and generates a positive voltage (VPOS) in the black reset period. The method of claim 2,
A gate drive IC generating a scan pulse and supplying the scan pulse to the display panel; And
And a data drive IC configured to supply a negative voltage to the display panel as a reset voltage in the white reset period, and supply the positive voltage to the display panel as a reset voltage in the black reset period.
The power supply unit further generates a logic power supply voltage (VCC), a base low voltage (VSS), a common voltage (Vcom), a gate high voltage (VGH) and a gate low voltage (VGL). The method of claim 3,
The data drive IC,
In the white reset period, a negative data voltage required for driving white reset is supplied to the display panel.
An electrophoretic display device comprising supplying a negative data voltage required for black reset driving to the display panel during a black reset period. The method of claim 3,
The power supply unit,
And at least one voltage of a negative data voltage and a positive data voltage during a data update period is supplied to the data live IC. 6. The method of claim 5,
The data drive IC,
And at least one of a negative data voltage and a positive data voltage is supplied as image data to the display panel during the data update period. Generating, by the controller, a power control signal for controlling generation of a driving voltage used when updating image data for switching from the previous screen to the next screen;
Generating only a driving voltage necessary for a white reset period, a black reset period, and a data update period based on the power control signal at the power supply unit; And
And updating the image data by using the driving voltage generated by the power supply unit. The method of claim 7, wherein
And generating a negative voltage VNEG in a white reset period and a positive voltage VPOS in a black reset period based on the power control signal. The method of claim 8,
And supplying a negative data voltage to the display panel as a reset voltage in the white reset period, and supplying a positive voltage to the display panel as a reset voltage in the black reset period. The method of claim 8,
And at least one voltage of a negative data voltage and a positive data voltage is supplied to the display panel during the data update period.

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