KR20080055133A - Display device and method of driving the same - Google Patents

Abstract

A display device and a driving method thereof are provided to enhance luminance thereof by varying a frame frequency according to the whole luminance of a panel. A display device includes a panel(100), a frequency generator(104), and a controller(102). The panel includes plural sub-pixels, which are formed at areas that data and scan lines cross each other. The frequency generator generates a frame frequency. The controller controls the panel and the frequency generator so as to vary the frame frequency, which is generated from the frame generator according to at least part of luminance of the panel. The more the luminance of the panel increases, the less the frame frequency.

Description

DISPLAY DEVICE AND METHOD OF DRIVING THE SAME}

1 is a view showing a display device according to a first embodiment of the present invention.

FIG. 2 is a timing diagram illustrating a flow of scan signals when the panel emits light with low luminance in the display device of FIG. 1.

FIG. 3 is a timing diagram illustrating a flow of scan signals when a panel emits light with high brightness in the display device of FIG. 1.

4 is a diagram illustrating a frequency adjustment process according to a white pattern.

5 is a block diagram illustrating the controller of FIG. 1 according to an exemplary embodiment of the present invention.

6 is a block diagram illustrating the frequency generator of FIG. 1 according to an exemplary embodiment of the present invention.

7 illustrates a display device according to a second exemplary embodiment of the present invention.

The present invention relates to a display device and a method of driving the same, and more particularly, to a display device for changing the frame frequency according to the overall brightness of the panel and a method of driving the same.

The display device is a device for displaying a predetermined image, and includes a panel and a driver.

The panel includes a plurality of sub pixels, and the driver drives the sub pixels.

In general, the display element drives the subpixels using one frame frequency. However, the frame frequency is set high so that a screen flickering, that is, flicker, does not occur to a user viewing the display device. However, in practice, the flicker phenomenon is mainly a phenomenon that occurs only when the panel emits light at low luminance, and therefore, using the frame frequency in the same manner as the low luminance even at high luminance causes a lot of loss in terms of luminance.

SUMMARY OF THE INVENTION An object of the present invention is to provide a display element and a method of driving the same, which changes the frame frequency according to the luminance of the panel so that the luminance is improved at high luminance.

In order to achieve the above object, the display device according to an embodiment of the present invention includes a panel, a frequency generator and a control unit. The panel includes a plurality of subpixels formed in intersection regions of data lines and scan lines. The frequency generator generates a frame frequency. The controller controls the panel and the frequency generator so that the frame frequency generated from the frequency generator is changed according to the luminance of at least a portion of the panel.

A driver for driving a panel including a plurality of subpixels formed in intersection regions of data lines and scan lines according to an exemplary embodiment of the present invention includes a frequency generator and a controller. The frequency generator generates a frame frequency. The controller controls the frequency generator to change the frame frequency generated from the frequency generator according to the luminance of at least a portion of the panel.

According to a preferred embodiment of the present invention, a method of driving a display device including a panel having a plurality of subpixels formed in intersection regions of data lines and scan lines may include detecting a luminance of at least a portion of the panel. ; And driving the panel at a frame frequency corresponding to the detected brightness of the panel.

The display device and the method of driving the same according to the present invention change the frame frequency according to the overall luminance of the panel, and thus have an advantage of improving the luminance at high luminance while preventing flicker.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a display device according to a first embodiment of the present invention.

Referring to FIG. 1, the display element of the present embodiment includes a panel 100 and a driver.

The display device according to an exemplary embodiment of the present invention includes an organic electroluminescent device (PDP), a plasma dispaly panel (PDP), a liquid crystal display (LCD), and the like.

The panel 100 includes a plurality of sub pixels E11 to Emn formed in regions where the data lines D1 to Dm and the scan lines S1 to Sn cross. Here, three consecutively located sub-pixels, for example, E11, E21 and E31 form one pixel.

When the display device of the present embodiment is an organic electroluminescent device, each of the sub pixels E11 to Emn includes a first electrode layer, an organic material layer, and a second electrode layer sequentially formed on a substrate.

One of the electrode layers is a positive electrode and the other is a negative electrode.

The organic material layer includes a light emitting layer made of an organic material corresponding to red light, green light, or blue light. Thus, when predetermined voltages are applied to the electrode layers, holes and holes transferred from the electrode layers combine in the organic layer to form excitons, and then the light corresponding to decomposition energy is decomposed as the excitons are decomposed. The organic material layer is preferably emitted from the light emitting layer.

The driver includes a controller 102, a frequency generator 104, a first scan driver 106, a second scan driver 108, and a data driver 110.

The controller 102 sequentially receives a plurality of display data from an external device (not shown), stores the received display data, and according to the received display data, the frequency generator 104 and the first scan driver 106. ), The second scan driver 108 and the data driver 110 are controlled. In addition, the control unit 102 detects the luminance of the panel 100 to be emitted through the received display data, and transmits the detection result to the frequency generating unit 104. Alternatively, the controller 102 transmits a frequency generation command signal to the frequency generator 104 instructing to generate a predetermined frequency according to the detection result.

The frequency generator 104 generates a predetermined frame frequency according to the detection result or the frequency generation command signal transmitted from the controller 102. Here, the frame means a screen when the panel 100 implements an image as a whole. In detail, the frame is obtained when the sub-pixels E11 to Emn associated with the scan lines S1 to Sn emit light as the scan lines S1 to Sn are selected one by one. Point to the screen.

For example, the frequency generator 104 generates a predetermined frame frequency, for example 120 Hz, according to the detection result or the frequency generation command signal.

In another exemplary embodiment of the present invention, the frequency generator 104 generates a plurality of frame frequencies, and generates one of the frame frequencies according to the detection result or the frequency generation command signal. Select as. Detailed description thereof will be described below with reference to the accompanying drawings.

The first scan driver 106 scans the first scan signals having the frame frequency generated from the frequency generator 104 under the control of the controller 102, for example, an odd-numbered scan of the scan lines S1 to Sn. Send to the lines.

The second scan driver 108 transmits second scan signals having the frame frequency to the remaining scan lines, for example, even-numbered scan lines, under the control of the controller 102.

As a result, scan lines S1 to Sn are sequentially selected by the first and second scan signals.

The data driver 110 includes a plurality of current sources IS1 to ISm having a driving voltage Vcc as a reference voltage, and corresponds to the display data and receives data currents generated from the current sources IS1 to ISm. To D1 to Dm.

Hereinafter, the driving method of the display element of the present embodiment will be described in detail with reference to FIGS. 2 and 3.

FIG. 2 is a timing diagram illustrating the flow of scan signals when the panel emits light with low brightness in the display device of FIG. 1, and FIG. 3 illustrates the flow of scan signals when the panel emits light with high brightness in the display device of FIG. 1. The timing diagram shown.

First, referring to FIG. 2, the first and second scan signals SP1 to SPn are provided to the scan lines S1 to Sn.

When the scan signal SP1 has a low logic in the T1 section, the other scan signals S2 to Sn have the same voltage as the high logic, for example, the driving voltage Vcc, in the T1 section. In this case, data currents generated from the data driver 110 flow to, for example, ground through the data lines D1 to Dm, the subpixels E11 to Em1, and the scan line S1. As a result, only the sub pixels E11 to Em1 associated with the scan line S1 having the low logic in the T1 period emit light.

As shown in FIG. 2 and FIG. 3, the display device driving as described above has different frame frequencies according to the luminance of the entire panel 100.

For example, when the overall luminance of the panel 100 emits light at low luminance, for example, a gray scale of 40% or less, the frame frequency has a high frequency, for example 120 Hz. As a result, as shown in FIG. 2, scan signals SP1 to SPn having 120 μs are transmitted to the scan lines S1 to Sn. Here, when the number of scan signals SP1 to SPn is 96 and the length of the frame frequency is 8.33 msec, the one-low logic period T1, T2,..., Or Tn has 86.77 μsec.

On the other hand, when the luminance of the panel 100 emits light with high luminance, for example, 80% gradation as shown in Fig. 3, the frame frequency has a low frequency, for example, 80 Hz. As a result, as shown in FIG. 3, scan signals SP1 to SPn having 80 μs are transmitted to the scan lines S1 to Sn. Here, when the number of scan signals SP1 to SPn is 96 and the length of the frame frequency is 12.5 msec, the one-low logic period T1, T2,..., Or Tn has 130.2 μsec.

As described above, the display device of the present embodiment varies the frame frequency according to the overall brightness of the panel 100. Preferably, the display device divides the overall luminance of the panel 100 step by step, and accordingly sets the frame frequency step by step as shown in Table 1 below.

Panel brightness Gradient below 40% 40% to 60% gradation 60% to 80% gradation 80% or more Frame frequency 120㎐ 100㎐ 80 ㎐ 60㎐

As can be seen in Table 1 above, the display element of the present embodiment sets the frame frequency lower as the overall brightness of the panel 100 is higher.

In detail, when the overall brightness of the panel 100 is low, the display element sets the frame frequency high so that a user viewing the display element does not recognize the flickering of the screen, that is, the flicker phenomenon is prevented. . On the other hand, when the overall brightness of the panel 100 is high, the flicker does not occur well. In this case, as shown in FIG. Set the frame frequency low to improve brightness.

As a result, the display element of the present embodiment can have the effect of improving the luminance at high brightness while preventing the flicker phenomenon.

In the above, although the frame frequency is adjusted according to the overall luminance of the panel 100, as shown in FIG. 4 below, after displaying a white pattern on a part of the panel 100, the luminance of the white pattern of the panel 100 is displayed. The frame frequency can also be adjusted accordingly.

4 is a diagram illustrating a frequency adjustment process according to a white pattern.

As shown in FIG. 4, a white pattern is displayed on a part of the panel 10, and as a result, the luminance level changes according to the area of the white pattern. In this environment, the display element of the present invention lowers the frame frequency as the luminance level increases, so that the times in the low logic period also change.

For convenience of explanation, it will be assumed that the frame frequency is adjusted according to the overall brightness of the panel 100.

5 is a block diagram illustrating the controller of FIG. 1 according to an exemplary embodiment of the present invention, and FIG. 6 is a block diagram illustrating the frequency generator of FIG. 1 according to an exemplary embodiment of the present invention.

Referring to FIG. 5, the control unit 102 includes a data storage unit 400 and a determination unit 402.

The data storage unit 400 stores display data transmitted from the external device, for example, in a latch.

The determination unit 402 reads display data from the data storage unit 400 and analyzes the read display data to detect luminance of the panel 100.

Subsequently, the determination unit 402 transmits the frequency generation command signal FCS to the frequency generation unit 104 according to the detection result.

The frequency generator 104 generates a plurality of frame frequencies as shown in FIG. 6, and determines the frequency signal FS having predetermined frame frequency information according to a detection result included in the frequency generation command signal FCS. Send to 104. For example, when the luminance of the panel 100 corresponds to the first level (Level 1), the frequency generator 104 may have a frame of 120 Hz among frame frequencies of 120 Hz, 100 Hz, 80 Hz, and 60 Hz. The frequency is selected and the frequency signal FS having the selected frame frequency information is transmitted to the determination unit 104.

The determination unit 402 transmits the control signals DCS, SCS1 and SCS2 to the scan drivers 106 and 108 and the data driver 110 according to the frequency signal FS, respectively. Accordingly, the scan drivers 106 and 108 transmit scan signals SP1 to SPn having the selected frame frequency to the scan lines S1 to Sn. In addition, the data driver 110 corresponds to the display data and provides data currents to the data lines D1 to Dm that are synchronized with the scan signals SP1 to SPn.

7 illustrates a display device according to a second exemplary embodiment of the present invention.

Referring to FIG. 7, the display device according to the present exemplary embodiment includes a panel 600, a controller 602, a frequency generator 604, a scan driver 606, and a data driver 608.

Since the other components except for the scan driver 606 perform the same functions as the components of the first embodiment, the description thereof will be omitted.

Unlike the first embodiment, the scan driver 606 is formed in one direction of the panel 600 and transmits scan signals to the scan lines S1 to Sn.

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art having ordinary knowledge of the present invention will be able to make various modifications, changes, additions within the spirit and scope of the present invention, such modifications, changes and Additions should be considered to be within the scope of the following claims.

As described above, the display device and the method of driving the same according to the present invention change the frame frequency according to the overall brightness of the panel, and thus have the advantage of improving the brightness at high brightness while preventing the flicker phenomenon.

Claims (19)

A panel including a plurality of subpixels formed in intersection regions of the data lines and the scan lines; A frequency generator for generating a frame frequency; And And a controller which controls the panel and the frequency generator so that the frame frequency generated from the frequency generator is changed according to the luminance of at least a portion of the panel. The display device of claim 1, wherein the frame frequency is lowered as the brightness of the panel increases. The display device of claim 1, wherein the controller receives display data from an external device and determines the luminance of the panel based on the received display data. The method of claim 3, wherein the control unit, A data storage unit for storing the received display data; And And a determination unit determining the luminance of the panel based on the display data read out from the data storage unit. The display device of claim 1, wherein the display device comprises: A scan driver to transmit scan signals having the frame frequency to the scan lines; And And a data driver for transmitting data currents synchronized with the scan signals to the data lines. The method of claim 1, wherein the at least one subpixel is: Display device comprising a light emitting layer made of an organic material. The display device according to claim 1, wherein the luminance of the panel is a luminance according to a white pattern. A driver for driving a panel including a plurality of subpixels formed in intersection regions of data lines and scan lines. A frequency generator for generating a frame frequency; And And a controller for controlling the frequency generator so that the frame frequency generated from the frequency generator is changed according to the luminance of at least a portion of the panel. The method of claim 8, wherein the frequency generator generates a plurality of frame frequencies, The control unit selects a frame frequency corresponding to the luminance of the panel among the frame frequencies. The driver of claim 8, wherein the frame frequency is lowered as the brightness of the panel increases. The method of claim 10, wherein the driver, The apparatus may further include a scan driver configured to transmit scan signals having the frame frequency to the scan lines. The light emission time of at least one scan line is longer as the brightness of the panel is increased. The driver of claim 8, wherein the frame frequency changes stepwise according to a change in luminance of the panel. The driver of claim 8, wherein the luminance of the panel is based on a white pattern. A method of driving a display device including a panel having a plurality of subpixels formed in intersection regions of data lines and scan lines, the method comprising: Detecting brightness of at least a portion of the panel; And And driving the panel at a frame frequency corresponding to the detected brightness of the panel. 15. The method of claim 14, wherein the brightness of the panel is detected by analyzing display data input from an external device. The method of claim 14, wherein driving the panel comprises: Generating a plurality of frame frequencies; And Selecting a frame frequency corresponding to the detected luminance of the panel among the frame frequencies. The method of claim 16, wherein driving the panel comprises: Transmitting scan signals having the selected frame frequency to the scan lines; And And providing data currents synchronized with the scan signals to the data lines. The method of claim 14, wherein the frame frequency decreases as the luminance of the panel increases. 15. The method of claim 14, wherein the luminance of the panel is a luminance according to a white pattern.

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