KR102593331B1 - Display Device and Driving Method thereof - Google Patents

Abstract

The display device according to the present invention includes a display panel and a driving circuit. In the display panel, pixels are arranged in a matrix form with an intersection structure of data lines and gate lines. The driving circuit unit writes data to the display panel and displays preset information on at least a portion of the display panel during the standby mode period. Data lines are grouped into a plurality of data line groups, each of which includes one or more data lines. The driving circuit supplies data voltage for each data line group, but does not supply data voltage to at least one data line group during the standby mode period.

Description

Display device and driving method thereof}

The present invention relates to a display device having a standby mode display function and a method of driving the same.

Flat panel displays (FPDs) are widely used not only in desktop computer monitors but also in portable computers such as laptop computers and PDAs and mobile phone terminals due to their advantages of miniaturization and weight reduction. These flat panel displays include liquid crystal displays; LCD), Plasma Display Panel (PDP), Field Emission Display; FED) and Organic Light Emitting Diode Display (OLED).

Organic light-emitting diodes (OLEDs), which are self-luminous devices, include an anode electrode and a cathode electrode, and an organic compound layer formed between them. The organic compound layer consists of a hole transport layer (HTL), an emission layer (EML), and an electron transport layer (ETL). When a driving voltage is applied to the anode and cathode electrodes, holes passing through the hole transport layer (HTL) and electrons passing through the electron transport layer (ETL) are moved to the emitting layer (EML) to form excitons, and as a result, the emitting layer (EML) Visible light is generated. The active matrix type organic light emitting display device includes an organic light emitting diode (OLED) that emits light on its own, and is used in a variety of ways due to its advantages of fast response speed, luminous efficiency, brightness, and viewing angle.

Because reducing power consumption is a huge challenge for personal portable terminals using organic light-emitting diodes, it is common to stop driving the display device in standby mode, which does not display images.

Recently, in order to reduce the inconvenience of users having to restart the mobile terminal when viewing simple information such as the clock, a standby mode display function is used to always display information that is frequently checked, such as the clock, in a certain area of the display panel. A portable terminal with a appeared. The standby mode display function is also called the AOD (Always On Display) display function. During the standby mode display period, the mobile terminal does not drive the entire screen, but only a part of the screen, and always displays simple standby mode display images such as a clock, message, or picture. Because the video image of the standby mode display image rarely changes compared to a general video, each pixel displays the same image, resulting in severe deterioration of the pixels. Because of this, a burn-in phenomenon occurs in the pixels of the organic light emitting diode. The burn-in phenomenon refers to the deterioration of the organic light emitting diodes of pixels that display fixed patterns (characters, images, etc.) for a long time in an organic light emitting display device, resulting in unrecoverable afterimages in which the previous fixed pattern is visible even when a different image is displayed on the pixels. Therefore, the burn-in phenomenon causes afterimages to appear even in everyday videos that use the entire screen.

The present invention is intended to provide a display device that can improve pixel burn-in while reducing power consumption.

In order to achieve the above object, the display device according to the present invention includes a display panel and a driving circuit. In the display panel, pixels are arranged in a matrix form with an intersection structure of data lines and gate lines. The driving circuit unit writes data to the display panel and displays preset information on at least a portion of the display panel during the standby mode period. Data lines are grouped into a plurality of data line groups, each of which includes one or more data lines. The driving circuit supplies data voltage for each data line group, but does not supply data voltage to at least one data line group during the standby mode period.

According to embodiments of the present specification, power consumption can be reduced by driving data lines alternately during the standby mode period.

Additionally, the data lines are alternately driven during the standby mode period, thereby improving pixel deterioration caused by displaying a fixed image for a long period of time.

1 and 2 are perspective views showing a display device according to the present invention.
Figure 3 is a block diagram showing the configuration of a display device according to the present invention.
Figure 4 is a diagram showing the array structure of the display panel.
Figure 5 is a diagram showing a data driver and pixel structure.
Figure 6 is a diagram showing the driving period according to the present invention.
Figure 7 is a diagram showing an image display period according to the present invention.
Figure 8 is a diagram showing an example of a standby mode image.
Figure 9 is a diagram showing an example of data line grouping.
10 and 11 are diagrams showing a method of driving the data driver according to the first embodiment.
12 and 13 are diagrams showing a method of driving the data driver according to the second embodiment.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. Like reference numerals refer to substantially the same elements throughout the specification. In the following description, if it is determined that a detailed description of a known function or configuration related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted.

1 and 2 are diagrams schematically showing a portable display device according to an embodiment of the present invention. 1 and 2 illustrate a mobile terminal with a full touch screen structure, but it should be noted that the present invention is not limited thereto.

1 and 2, the portable display device of the present invention includes a display panel 10, a front cover 101 surrounding the display panel 10, a back cover 103, and a main board ( 104) and a battery 105.

Touch sensors may be disposed on the entire screen of the display panel 10. The display panel driving circuit includes a drive IC (DIC) and a flexible circuit board (FPC) connecting the drive IC (DIC) to the main board 104. The drive IC 46 writes image data input through the main board 104 into pixels of the display panel 10.

The front cover 101 includes tempered glass that covers the display panel 10. The front cover 101 covers the front of the mobile terminal. The screen of the display panel 10 is exposed on the front of the mobile terminal. A front camera and various sensors may be placed on the front of the mobile terminal. A rear camera and various sensors may be placed on the back of the mobile terminal.

A mid frame 102, a main board 104, a battery 105, etc. are disposed in the space between the front cover 101 and the back cover 103. The mid frame 102 supports the display panel 10 and spatially separates the display panel 10 and the main board 104. The flexible circuit board (FPC) of the display device is connected to the main board 104. An A/V (Audio/Video) input unit, a user input unit, a speaker, a microphone, etc. are installed on the front cover 101 and the back cover 103. A/U input, user input, speaker, and microphone are connected to the main board 104. The user input unit may be composed of a touch key pad, dome switch, touch pad, jog wheel, jog switch, etc.

The main board 104 includes a display device, a wireless communication module, a short-range communication module, a mobile communication module, a broadcast reception module, an A/U input unit, a Global Position System (GPS) module, and a power circuit. A user input unit, speaker, microphone, battery 105, etc. are connected to the main board 104. The power circuit removes noise from the voltage of the battery 105 and supplies it to the circuit of the main board 104 and the module power supply of the display panel driving circuit. The main board 104 of the mobile device may include an application processor (AP). The AP transmits and receives image data to and from the drive IC (DIC) of the display device through MIPI (Mobile industry processor interface).

The main board 14 may be a main board for a phone system, TV (Television) system, set-top box, navigation system, DVD player, Blu-ray player, personal computer (PC), home theater system, etc.

Figure 3 is a block diagram showing the configuration of an organic light emitting display device according to the present invention. FIG. 4 is a diagram showing the array arrangement of the display panel shown in FIG. 3. FIG. 3 shows a display device in which the driving circuit shown in FIG. 2 is divided into a timing controller 11, a data driver 12, and a gate driver 13 according to the functional configuration.

Referring to FIG. 3, the organic light emitting display device according to an embodiment of the present invention includes a display panel 10 on which pixels (PXL) are formed, a timing controller 11, a data driver 12, and a gate driver 13. Equipped with

A plurality of pixels P are arranged in a matrix form on the display panel 10. Each pixel (P) is connected to the data line unit 14 and the gate line unit 15. The data line unit 14 includes a data line (DL) and a reference voltage line (VIL). The gate line unit 15 includes a plurality of gate lines.

The semiconductor layer of the transistors constituting the pixel P may be an oxide semiconductor layer, amorphous silicon (a-Si), polycrystalline silicon (poly-Si), or an organic semiconductor.

The timing controller 11 controls the operation timing of the data driver 12 based on timing signals such as the vertical synchronization signal (Vsync), the horizontal synchronization signal (Hsync), the dot clock signal (DCLK), and the data enable signal (DE). A data control signal (DDC) for controlling and a gate control signal (GDC) for controlling the operation timing of the gate driver 13 are generated. In addition, the timing controller 11 modulates the input digital video data (DATA) with reference to the digital sensing voltage value supplied from the data driver 12, thereby providing digital compensation to compensate for changes in the threshold voltage and mobility of the driving transistor. After generating data (MDATA), this digital compensation data (MDATA) is supplied to the data driver 12.

During sensing operation, the data driver 12 supplies a sensing data voltage synchronized to the first scanning signal for sensing to the pixels P based on the data control signal (DDC) from the timing controller 11. , the sensing voltages input from the display panel 10 through the reference voltage line are converted into digital values and supplied to the timing controller 11. When driving an image display, the data driver 12 converts the digital compensation data (MDATA) input from the timing controller 11 based on the data control signal (DDC) into an image display data voltage, and then converts the image display data The voltage is synchronized with the first scan signal for image display and supplied to the data lines.

The gate driver 13 generates a gate pulse based on the gate control signal (GDC) from the timing controller 11. The gate pulse includes a scan signal, a sense signal, and a black data control signal. The black data control signal maintains the gate-off voltage during sensing operation. The timing of the scan signal and the sense signal may vary during the sensing operation and the display operation. The gate driver 13 may be formed directly on the display panel 10 according to the Gate-Driver In Panel (GIP) method.

FIG. 4 is a diagram showing the array arrangement of the display panel shown in FIG. 3, and FIG. 5 is a diagram showing the pixel structure.

Figure 5 is a diagram showing a pixel structure and a data driver according to the present invention.

3 to 5, each pixel is connected to the data driver 12 through the data line DL and the first reference voltage line VIL. A sensing capacitor Cx may be formed in the reference voltage line VIL to store the source voltage of the second node N2 as the sensing voltage Vsen.

The data driver 12 includes a digital-to-analog converter (DAC), an analog-to-digital converter (ADC), an initialization switch (SW1), and a sampling switch (SW2).

The digital-to-analog converter (DAC) can generate a data voltage (Vdata) for sensing under the control of the timing controller 11 during sensing operation and output it to the data line (DL). When driving an image display, the DAC can convert digital compensation data into a data voltage (Vdata) for image display under the control of the timing controller 11 and output it to the data line (DL).

The initialization switch (SW1) switches the current flow between the initialization voltage (Vpre) input terminal and the reference voltage line (VIL) in response to the initialization control signal (SPRE). The sampling switch (SW2) switches the current flow between the reference voltage line (VIL) and the analog-to-digital converter (ADC) in response to the sampling control signal (SSAM) during sensing operation, performing sensing of the reference voltage line (VIL) for a certain period of time. The source voltage of the driving transistor (DT) stored in the capacitor (Cx) is supplied to the ADC as a sensing voltage (Vsen). The ADC converts the analog sensing voltage stored in the sensing capacitor (Cx) into a digital value (Vsen) and supplies it to the timing controller (11). The sampling switch (SW2) continues to be turned off in response to the sampling control signal (SSAM) when the display is driven.

Each of the pixels P includes an organic light emitting diode (OLED) driving transistor DT, first and second transistors T1 and T2, and a capacitor Cst.

Organic light-emitting diodes (OLEDs) emit light by driving current supplied from a driving transistor (DT). A multi-layer organic compound layer is formed between the anode and cathode electrodes of an organic light-emitting diode (OLED).

The driving transistor (DT) controls the driving current (Ioled) flowing through the organic light-emitting diode (OLED) according to the gate-source voltage (Vgs). The driving transistor DT includes a gate electrode connected to the first node N1, a drain electrode connected to the input terminal of the high potential driving voltage EVDD, and a source electrode connected to the second node N2.

The storage capacitor Cst is connected between the first node N1 and the second node N2.

The first transistor T1 includes a gate electrode connected to an input terminal that supplies the scan signal SCAN, a drain electrode connected to the data line DL, and a source electrode connected to the first node N1.

The second transistor T2 includes a gate electrode connected to an input terminal that supplies the sense signal SEN, a drain electrode connected to the second node N2, and a source electrode connected to the reference voltage line VIL.

The reference voltage Vref applied through the reference voltage line VIL may be selected within a voltage range sufficiently lower than the operating voltage of the organic light emitting diode (OLED) so that the organic light emitting diode (OLED) does not emit light during the programming period. That is, the reference voltage (Vref) may be set equal to or lower than the low-potential driving voltage (VSS).

Figure 6 is a diagram showing the driving period of the organic light emitting display device according to the present invention.

Referring to FIG. 6, the driving period of the organic light emitting display device according to the present invention includes first and second non-display sections (X1, X2) and an image display section (X0).

The first non-display section (X1) is defined as the section from when power is turned on (PON) until tens to hundreds of frames have elapsed, and the second non-display section (X2) is from when power is turned off (POFF). It can be defined as a section that lasts from tens to hundreds of frames.

The image display period (X0) includes a display period (DF) in which data voltage is written to the pixels (P) and a vertical blank period (VB) in which no image data is written.

The compensation period is located outside the display period (DF). The compensation period may belong to the first and second non-display periods (X1, X2) or the vertical blank period (VB). During the compensation period, the data driver 12 extracts the threshold voltage (Vth) of the driving transistor (DT) and calculates the amount of change in the threshold voltage (Vth) based on this to generate a compensation data voltage.

The compensation period includes a programming period (Tpg), a sensing period (Tsen), and a sampling period (Tsam), respectively.

Figure 7 is a diagram showing the timing of scan signals and switch control signals during the display period among the image display sections.

The operation of the display period (DF) pixel (P) will be described in conjunction with FIGS. 5 and 7 as follows. The operation of each pixel P in the display period DF is the same, and the operation will be described focusing on one pixel P below.

The image display drive of the present invention is divided into ① period, ② period, and ③ period.

In period ①, the initialization switch (SW1) and the second transistor (ST2) are turned on to reset the second node (N2) to the initialization voltage (Vpre).

In period ②, the first transistor (ST1) is turned on and supplies the data voltage (Vdata) to the first node (N1). The data voltage (Vdata) may be an analog data voltage converted using digital compensation data (Mdata). At this time, the second node N2 maintains the initialization voltage Vpre through the second transistor ST2. Accordingly, in this period, the gate-to-source voltage (Vgs) of the driving transistor (DT) is programmed to a desired level.

In period ③, the first and second transistors (ST1, ST2) are turned off, and the driving transistor (DT) generates a driving current (Ioled) at a programmed level and applies it to the organic light emitting diode (OLED). Organic light-emitting diodes (OLEDs) display grayscale by emitting light with a brightness corresponding to the driving current (Ioled).

In period ② shown in FIG. 7, the data driver uses a different method of supplying the data voltage to the data line depending on the driving mode of the display device.

In the normal image display mode, the data driver 11 supplies data voltage to all data lines DL. And in standby mode, the data driver 11 supplies data voltage to some of the data lines DL.

Figure 8 is a diagram showing an example of a standby mode image.

Referring to FIG. 8, the standby mode image may be displayed only in a partial area of the display panel 10. The standby mode image may include information such as time and calendar.

In order to selectively drive the data lines DL in standby mode, the data lines are grouped into multiple data line groups.

Figure 9 is a diagram showing the grouping of data lines according to the present invention.

Referring to FIG. 9, the data lines DL1 to DL2m according to the present invention are grouped into first to mth data line groups GR1 to GRm.

The first to mth data line groups GR1 to GRm include one or more data lines DL. For example, as shown in FIG. 9, each of the data line groups GR1 to GRm includes two data lines. can do. Data lines belonging to each data line group (GR1 to GRm) are composed of adjacent data lines.

The data driver 11 supplies data voltage in groups in standby mode, but does not supply data voltage to at least one data line. As shown in FIG. 8, because the standby mode image displays simple information, the user can check the information displayed on the standby mode image in a short period of time. Therefore, the resolution of the standby mode image does not feel very important to the user. The data driver 11 of the present invention does not supply data voltage to certain data lines DL when displaying a standby mode image, thereby reducing power consumption.

FIG. 10 is a diagram showing a method of driving the data driver in standby mode according to the first embodiment, and FIG. 11 is a diagram showing light emission of pixels by the driving method shown in FIG. 10.

The driving method of the data lines grouped as shown in FIG. 9 is as follows.

10 and 11 show the first data line group GR1 among the odd-numbered data line groups GR(2n-1) and the second data line group GR2 among the even-numbered data line groups GR2n. An example is shown.

Referring to FIGS. 9 to 11, the data driver 11 according to the first embodiment supplies a data voltage to the first data line group GR1 during the k (k is a natural number) th frame period, and (k+ 1) During the second frame period, the data voltage is supplied to the second data line group (GR2).

As a result, during the k-th frame, pixels connected to the first data line group GR1 emit light, and pixels connected to the second data line group GR2 do not emit light. And during the (k+1)th frame, pixels connected to the second data line group GR2 emit light, and pixels connected to the first data line group GR1 do not emit light.

FIG. 12 is a diagram showing a method of driving the data driver in standby mode according to the second embodiment, and FIG. 13 is a diagram showing light emission of pixels by the driving method shown in FIG. 12. 12 and 13 show the first data line group, which is the first (3n-2) data line group, the second data line group, which is the first (3n-1) data line group, and the first 3n data line group. A third data line group is shown.

Referring to FIGS. 12 and 13, the data driver 11 supplies data voltage to the first and second data line groups GR1 and GR2, and the third data line group GR3 during the k-th frame period. Data voltage is not supplied to . Then, the data driver 11 supplies data voltages to the first and third data line groups GR1 and GR3 and supplies data voltages to the second data line group GR2 during the (k+1)th frame period. do not supply Then, the data driver 11 supplies data voltages to the second and third data line groups GR2 and GR3 and supplies data voltages to the first data line group GR1 during the (k+2)th frame period. do not supply

In this way, the data driver 11 can reduce power consumption by alternately driving the data line groups GR.

Embodiments of the present invention have been described focusing on embodiments in which a period for alternately driving data line groups (GR) is set as a frame period. However, the period for alternately driving the data line groups GR is not limited to this and may be set arbitrarily.

Through the above-described content, those skilled in the art will be able to see that various changes and modifications can be made without departing from the technical idea of the present invention. Therefore, the technical scope of the present invention should not be limited to what is described in the detailed description of the specification, but should be defined by the scope of the patent claims.

10: Display panel 11: Timing controller
12: data driver 13: gate driver
GR: Dataline Group

Claims (7)

A display panel in which pixels are arranged in a matrix form with an intersection structure of data lines and gate lines; and
A driving circuit unit that writes data to the display panel and displays preset information in at least a portion of the display area during a standby mode period,
The data lines are grouped into a plurality of data line groups each including one or more data lines,
The driving circuit supplies data voltage for each data line group,
The data lines belonging to the data line group are composed of adjacent data lines,
In a normal image display mode, the driving circuit supplies the data voltage to all the data lines,
In the standby mode period, supplying the data voltage to some of the data lines,
A display device that supplies the data voltage to one data line group during one frame period of the standby mode period, but does not supply the data voltage to another data line group at all.
According to claim 1,
The driving circuit part is
During the k (k is a natural number)-th frame period, a data voltage is supplied to an odd-numbered data line group among the data line groups,
A display device that alternately drives the data line groups by supplying a data voltage to an even-numbered data line group among the data line groups during the (k+1)th frame period.
According to claim 1,
The driving circuit part is
During the k-th frame period, a data voltage is supplied to the (3n-2)th data line group and the (3n-1)th data line group among the data line groups,
During the (k+1)th frame period, a data voltage is supplied to the (3n-2)th data line group and the 3nth data line group among the data line groups,
A display device that alternately drives the data line groups by supplying a data voltage to the (3n-1)th data line group and the 3nth data line group during the (k+2)th frame period.
According to claim 1,
During the standby mode period, the driving circuit
A display device that displays a clock, text, image, or other information that can be specified according to the user's selection.
In a method of driving a display device including a plurality of data line groups including one or more data lines,
A first step of not supplying any data voltage to at least one data line group during the k (k is a natural number) th frame period of the standby mode period; and
During the (k+1)th frame period of the standby mode period, a second step of supplying a data voltage to a data line group to which no data voltage was supplied in the kth frame period,
The data lines belonging to the data line group are composed of adjacent data lines,
In a general image display mode, the driving circuit supplies the data voltage to all the data lines, and in the standby mode period, supplies the data voltage to some of the data lines.
According to claim 5,
The first step supplies a data voltage to an odd-numbered data line group among the data line groups,
The second step is a method of driving a display device in which the data line groups are alternately driven by supplying a data voltage to the most numbered data line group among the data line groups.
According to claim 5,
The first step supplies a data voltage to the (3n-2)th data line group and the (3n-1)th data line group among the data line groups,
The second step supplies a data voltage to the (3n-2)th data line group and the 3nth data line group among the data line groups,
Following the second step, the step of supplying a data voltage to the (3n-1)th data line group and the 3nth data line group during the (k+1)th frame period, wherein the data line group A method of driving a display device that alternately drives the display device.

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