KR20160083371A - Display Device and Driving Method thereof - Google Patents

Abstract

Provided is a display device comprising a data operation unit and a compensation circuit unit. The data operation unit operates a display panel. The compensation circuit unit performs a compensation operation in response to stress applied to a device, when the display panel is folded or bent. The purpose of the present invention is to provide improved display quality and prevent a brightness change and discoloration.

Description

DISPLAY DEVICE AND DRIVING METHOD THEREOF

The present invention relates to a display device and a driving method thereof.

As the information technology is developed, the market of display devices, which is a connection medium between users and information, is getting larger. Accordingly, a liquid crystal display (LCD), an organic light emitting diode (OLED), an electrophoretic display (EPD), and a plasma display panel (PDP) ) Have been increasingly used.

Some of the above-described display devices, for example, a liquid crystal display device and an organic light emitting display device, include a display panel including a plurality of sub-pixels arranged in a matrix form and a driver for driving the display panel. The driving unit includes a scan driver for supplying a scan signal (or a gate signal) to the display panel, and a data driver for supplying a data signal to the display panel.

The display device displays a specific image as the display panel emits or transmits light based on the power outputted from the power supply unit, the scan driver and the data driver, and the scan signal and the data signal.

On the other hand, the display device described above is also implemented as a display panel in which a specific area can be realized in the form of having a curved surface or folding. Since such a display panel generally forms a device on a plastic substrate and bends or collapses a specific region, deformation of the substrate causes the device (transistor or the like) to be stretched or shrunk, thereby changing the characteristics of the device. Therefore, when the device is driven by the conventionally proposed method, a change in brightness or a change in color caused by a change in the characteristics of elements of the display panel is required, which is required to be improved.

In order to solve the problems of the background art described above, the present invention is to prevent or improve a change in luminance or color, and to improve the stability and reliability of the device as well as the display quality.

According to the present invention, there is provided a display device including a data driver and a compensation circuit. The data driver drives the display panel. The compensation circuit part performs a compensating operation corresponding to the stress the device receives when the display panel is bent or folded.

The compensation circuit part adjusts the digital value of the data signal transmitted to the data driver in response to the stress, adjusts the analog value of the data signal, or adjusts the data voltage output through the output terminal of the data driver.

The compensation circuit receives the change in characteristics of the device due to the stress through the sensing transistor included in the sub-pixel of the display panel, extracts a compensation coefficient corresponding to the characteristic change of the device, Adjusts the digital value of the signal.

The compensation circuit portion receives a change in the characteristics of the device due to the stress from all the subpixels of the display panel or receives a change in the characteristics of the device from the subpixel located in the region where the characteristic change of the device occurs when the display panel is bent or collapsed have.

The compensation circuit part can adjust the gamma only in the area where the characteristic change of the device occurs when the display panel is bent or collapsed.

The compensation circuit portion may change the gamma maximum voltage value based on the control signal provided from the circuit portion capable of sensing at least one of the region where the characteristic change of the element occurs, the bending region, and the bending angle when the display panel is bent or collapsed.

The compensation circuit part may include a dummy source amplifier part provided at an output terminal of the data driver for driving a region where a characteristic change of a device occurs when the display panel is bent or folded.

The dummy source amplifier section adjusts a data voltage output from the data driver based on a control signal provided from a circuit section capable of sensing at least one of an area where a characteristic change of the device occurs, a banding area, and a bending angle when the display panel is bent or collapsed The amplification factor may fluctuate.

In another aspect, the present invention provides a method of driving a display device. A driving method of a display device includes driving a display panel; Detecting a stress the device receives when the display panel is bent or folded; And performing a compensating operation corresponding to the stress the device receives.

The compensating operation may adjust the digital value of the data signal transmitted to the data driver in response to the stress, adjust the analog value of the data signal, or adjust the data voltage output through the output terminal of the data driver.

The present invention has an effect of preventing or improving a change in brightness or color and a display quality by applying a compensation circuit part capable of performing signal (or voltage) compensation corresponding to external stresses that bend or fold the display panel. In addition, the present invention has the effect of enhancing the stability and reliability of the bar device which can compensate the display panel in various ways when the display panel is bent or folded.

1 is a block diagram schematically showing an organic light emitting display device.
Fig. 2 is a schematic view showing the subpixel shown in Fig. 1. Fig.
3 is a top view of a first embodiment of a display panel.
4 is a top view of a second embodiment of a display panel.
Fig. 5 is a plan view of a display panel having a banding region; Fig.
6 is a block diagram for explaining the compensation concept of the first embodiment of the present invention;
7 is a plan view of a display panel having a banding region;
8 is a block diagram for explaining the compensation concept of the second embodiment of the present invention;
9 is a diagram illustrating an example of the configuration of a gamma unit;
10 is a block diagram for explaining a compensation concept of a third embodiment of the present invention;
11 is a diagram illustrating a configuration example of a data driver;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The display device according to the present invention is implemented with navigation, a video player, a personal computer (PC), a wearable (watch, glasses, etc.) and a mobile phone (smart phone). The display panel of the display device may be a liquid crystal display panel, an organic light emitting display panel, an electrophoretic display panel, a plasma display panel, or the like, but is not limited thereto. In the following description, an organic electroluminescent display device will be described as an example for convenience of explanation.

FIG. 1 is a block diagram schematically showing an organic light emitting display device, and FIG. 2 is a schematic diagram showing a subpixel shown in FIG.

1, the organic light emitting display includes an image supply unit 110, a timing control unit 120, a scan driving unit 130, a data driving unit 140, a gamma unit 145, a display panel 150, And a power supply unit 180 are included.

The display panel 150 displays an image corresponding to the scan signal and the data signal DATA output from the driving unit including the scan driver 130 and the data driver 140. The display panel 150 may be implemented as a top emission type, a bottom emission type, or a dual emission type.

The display panel 150 is realized by a shape in which a specific area has a curved surface or a folded shape (a curved shape or a folded shape) according to the material of the substrate. The display panel 150 displays a specific image as the sub-pixels SP positioned between the two substrates emit light corresponding to the driving current.

As shown in FIG. 2, one sub-pixel includes a switching transistor SW connected to (or formed at) an intersection of the scan line GL1 and the data line DL1 and the data supplied through the switching transistor SW And a pixel circuit PC that operates in response to the signal DATA. The pixel circuit PC includes a circuit such as a driving transistor, a storage capacitor, an organic light emitting diode, and a compensation circuit for compensating the circuit.

The subpixel corresponds to the data voltage stored in the storage capacitor, and when the driving transistor is turned on, the driving current is supplied to the organic light emitting diode located between the first power supply line (VDDEL) and the second power supply line (VSSEL). The organic light emitting diode emits light corresponding to the driving current.

The compensation circuit is a circuit for compensating the threshold voltage of the drive transistor and the like. The compensation circuit is composed of one or more thin film transistors, capacitors, and the like. The configuration of the compensation circuit is very various according to the compensation method, and a detailed illustration and description thereof are omitted. The thin film transistor is implemented based on low temperature polysilicon (LTPS), amorphous silicon (a-Si), oxide or organic semiconductor layers.

The image supply unit 110 processes the data signal and outputs the image signal together with a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, and a clock signal. The image supply unit 110 supplies a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, a clock signal, and a data signal to the timing control unit 120.

The timing controller 120 receives a data signal and the like from the image supply unit 110 and controls the operation timing of the data driver 140 and the gate timing control signal GDC for controlling the operation timing of the scan driver 130 And outputs a data timing control signal DDC. The timing controller 120 supplies the data driver 140 with the data signal DATA along with the data timing control signal DDC.

The scan driver 130 outputs a scan signal while shifting the level of the gate voltage in response to the gate timing control signal GDC supplied from the timing controller 120. The scan driver 130 includes a level shifter and a shift register. The scan driver 130 supplies the scan signals to the sub-pixels SP included in the display panel 150 through the scan lines GL1 to GLm. The scan driver 130 may be formed on the display panel 150 in the form of a gate in panel or an integrated circuit (IC). The portion of the scan driver 130 formed in a gate-in-panel manner is a shift register.

The data driver 140 samples and latches the data signal DATA in response to the data timing control signal DDC supplied from the timing controller 120 and outputs the sampled data signal DATA corresponding to the gamma reference voltage GMA provided from the gamma unit 145 Converts the digital signal into an analog signal and outputs it. The data driver 140 supplies the data signal DATA to the sub-pixels SP included in the display panel 150 through the data lines DL1 to DLn. The data driver 140 may be formed in the form of an integrated circuit (IC).

The power supply unit 180 generates a first power (VDDEL) and a second power (VSSEL) to be supplied to the display panel 150. The first power source VDDEL corresponds to a high potential power source and the second power source VSSEL corresponds to a low potential power source. The power supply unit 180 generates power to be supplied to the scan driver 130 and the data driver 140 as well as the power supplies VDDEL and VSSEL to be supplied to the display panel 150 based on the input power supplied from the outside.

The display device includes a display panel 150 based on the power supply VDDEL and VSSEL output from the power supply 180 and the scan and data signals DATA output from the scan driver 130 and the data driver 140, So that a specific image is displayed.

Fig. 3 is a top view of a first embodiment of a display panel, and Fig. 4 is a top view of a second embodiment of a display panel.

As shown in FIGS. 3 and 4, the display devices 100 and 200 are implemented as a display panel in which left and right display areas AAL and AAR are folded with respect to a center display area AAS.

The display device 100 according to the first exemplary embodiment is implemented in such a manner that the left and right display areas AAL and AAR of the display panel are folded toward the direction in which the user USR is located. On the other hand, the display device 200 according to the second exemplary embodiment is implemented in such a manner that the left and right display areas AAL and AAR of the display panel are folded toward the direction opposite to the user USR.

In order to manufacture the display panel in the above-described form, an element (transistor, organic light emitting diode, etc.) must be formed on a substrate such as a plastic (or resin). In order to form the left and right display areas AAL and AAR of the display panel, the bending areas BL and BR located on the left and right sides should be bent or folded.

However, when the display panel is bent or folded in this form, the device is stretched or shrunk due to deformation (physical deformation) of the substrate, and as a result, the characteristics of the device are changed.

Therefore, when the device is driven in a conventionally proposed manner, a change in brightness or color change caused by a change in characteristics of the device appears in the left and right display regions (AAL, AAR) of the central display region AAS of the display panel This is required to be improved.

≪ Embodiment 1 >

FIG. 5 is a plan view of a display panel having a banding region, and FIG. 6 is a block diagram for explaining the compensation concept of the first embodiment of the present invention.

5, the display device according to the first embodiment of the present invention includes banding regions BL and BR formed so as to be tangent to the left and right display regions AAL and AAR with respect to the center display region AAS Based display panel.

The first embodiment of the present invention is characterized in that the left and right display regions (pixels) in which the luminance and color difference are generated as compared with the central display region AAS corresponding to the planar region due to the characteristic change of the element (transistor, for example) AAL, AAR) (the region where physical deformation causes changes in the characteristics of the device relative to the central display area).

Particularly, the first embodiment of the present invention has a circuit capable of sensing characteristics of a device (e.g., a transistor) in real time, and obtains a deviation that causes luminance and color difference, and compensates it with a data signal.

The reason why the luminance and color difference are compensated by the data signal as in the first embodiment of the present invention is that the variation of the driving current due to the characteristic change of the driving transistor when the display panel is bent or folded is large. Therefore, in the following description, the compensation of the data signal is an example, but the power supply VDDEL may also be compensated.

6 (a), an external compensation unit 160 is included in the first embodiment of the present invention. The external compensation unit 160 senses the characteristics of transistors (for example, driving transistors) included in all the subpixels of the display panel 150 during driving of the apparatus, Compensates the data signal in response to the deviation and outputs the compensated data signal. 6, an AP video signal refers to a video signal stored in the video supply unit 110. In FIG.

A method of sensing the characteristics of a transistor (e.g., a driving transistor) included in all the subpixels of the display panel 150 uses a sensing transistor included in the subpixel.

The sensing transistor can sense the characteristics of a transistor (for example, a driving transistor) included in the sub pixel at least every N (N is an integer equal to or greater than 1) frame. The data obtained through the sensing is transmitted to the external compensation unit 160 (and / or the data driving unit).

The external compensation unit 160 extracts the compensation coefficient stored in the memory unit 165 corresponding to the change (threshold voltage, current mobility, etc.) of the driving transistor obtained through the sensing transistor and adds the compensation coefficient to the data signal Thereby compensating the data signal. That is, the compensation coefficient of the memory unit 165 includes not only the first compensation coefficient for compensating the deterioration of the driving transistor, but also a second compensation coefficient for compensating for the stress generated when the display panel is bent or folded. The memory unit 165 may be a flash memory, but is not limited thereto.

Therefore, the external compensation unit 160 extracts a compensation coefficient corresponding thereto from the memory unit 165 when any stress occurs due to an external variable such as a bending or folding of a specific area of the display panel 150, Thereby compensating (or improving) the luminance and color difference. In this case, since the data signal is compensated similarly to the Mura compensation, the uniformity of the luminance can be maintained.

On the other hand, the external compensation unit 160 can recognize the initial characteristics of all transistors through initial external compensation. Therefore, when stress is generated in the driving transistor in the process of bending or folding the display panel, it is possible to compensate (or improve) the luminance and color difference by compensating the data signal for the changed characteristics of the driving transistor by performing additional sensing.

However, when sensing is performed to re-detect the characteristics of all the transistors, an excessive time may be required for the calculation time for calculating the sensing time and the compensation coefficient. Therefore, the present invention uses the following method.

6 (b), the external compensating unit 160 compensates for an area (a left and right display region, a banding region, or a left and right display region and a left and right display region) caused by the banding of the display panel 150 Banding area).

The external compensation unit 160 selectively drives a sensing transistor located in a region where a characteristic change of the transistor occurs, and senses stress, such as a driving transistor, generated in this region. The sensing transistor transmits a bending stress (BS) corresponding to a stress to a driving transistor generated in this region to the external compensation section 160.

The compensation coefficient changing unit 168 of the external compensation unit 160 changes (or updates) the second compensation coefficient stored in the memory unit 165 based on the banding stress (BS) transmitted from the sensing transistor. The second compensation coefficient is a compensation value capable of compensating for a change in a region where a characteristic change of the transistor occurs when the display panel is bent or folded.

The compensation coefficient changing unit 168 outputs a compensation coefficient change value CC provided by the self-operation to the memory unit 165 to change (or update) the second compensation coefficient based on the banding stress (BS) .

Therefore, in order to prevent an excessive time from being required for the sensing time and the calculation time when the characteristics of all the transistors are re-detected, the external compensation unit 160 performs additional sensing only in the region designated as the region where the characteristic change of the transistor occurs Only the changed portion of the initial transistor characteristics is compensated.

The first embodiment of the present invention compensates for problems occurring when the display panel is bent or folded by using the sensing transistor and the external compensator included in the subpixel.

≪ Embodiment 2 >

FIG. 7 is a plan view of a display panel having a banding region, FIG. 8 is a block diagram for explaining the compensation concept of the second embodiment of the present invention, and FIG.

7, the display device according to the second embodiment of the present invention includes banding regions BL and BR formed so as to be tangent to the left and right display regions AAL and AAR with respect to the center display region AAS Based display panel.

The second embodiment of the present invention is characterized in that the left and right display regions (for example, TFTs) in which luminance and color difference are generated as compared with the central display region AAS corresponding to the planar region due to the characteristic change of the element AAL, AAR) (the region where physical deformation causes changes in the characteristics of the device relative to the central display area).

8, the second embodiment of the present invention includes a first gamma unit FG for generating a first gamma reference voltage GMAF of the central display area AAS, The gamma unit 145 having the second gamma unit BG for generating the second gamma reference voltage GMAB of the second gamma reference voltage GMAB is used to compensate for the deviation causing the luminance and color difference. Gamma portion 145 is implemented in a manner that generates gamma reference voltages independently for red, green, and blue.

The second embodiment of the present invention is effective when the subpixel includes the internal compensation part. This is because the characteristic of the initial transistor (driving transistor) can not be sensed in the case of the internal compensation section.

The gamma unit 145 includes a second gamma unit BG capable of adjusting the gamma reference voltage only in a region where a change in characteristics of the device is caused by the physical deformation, such as the left and right display regions AAL and AAS, .

The second gamma unit BG receives the gamma voltage control signal GMX from the circuit unit capable of sensing the banding characteristics of the timing control unit and the display panel (the area where the device characteristics are changed due to banding, the banding area, the bending angle, And changes the gamma maximum voltage value based on the supplied voltage.

As shown in FIG. 9, the second gamma unit BG adjusts its gamma maximum voltage Vreg2 out based on the gamma maximum voltage value Vreg1 out of the first gamma unit FG. Therefore, when there is a compensation for the left and right display areas AAL and AAR due to the physical deformation of the display panel, the gamma maximum voltage value Vreg2 out of the second gamma unit BG and the gamma value of the first gamma unit FG The maximum voltage value Vreg1 out is set differently.

However, when there is no compensation for the left and right display areas AAL and AAR, the gamma maximum voltage value Vreg2 out of the second gamma unit BG and the gamma maximum voltage value Vreg1 of the first gamma unit FG out are set to be the same. As a result, the voltage deviation between the first gamma unit FG and the second gamma unit BG will be minimized, and the problem of image quality deviation between the central display area AAS and the left and right display areas AAL and AAR occurs .

The second embodiment of the present invention compensates for a problem caused by bending or folding the display panel using a gamma portion that can vary the data voltage only in a region where a characteristic change of the device occurs due to physical deformation of the display panel.

≪ Third Embodiment >

FIG. 10 is a block diagram for explaining the compensation concept of the third embodiment of the present invention, and FIG. 11 is a diagram illustrating the configuration of a data driver.

10, a third embodiment of the present invention includes a first data driver 140a for outputting a data voltage to a central display area AAS of a display panel, and a second data driver 140b for outputting a data voltage to the right display area AAR And the data driving unit 140 having the second data driver 140b for compensating for the deviation that causes the luminance and color difference.

The first data driver 140a includes a latch unit for latching a data signal and a source output unit 143 including a DA conversion unit for converting a digital data signal into an analog data voltage and a source output unit 143 And a source amplifier unit 148 for amplifying and outputting the output data voltage.

The first data driver 140a outputs a data voltage to the central display area AAS corresponding to a flat area of the display panel. Therefore, since the first data driver 140a is independent of the physical deformation of the display panel, the data voltage is output without compensation.

The second data driver 140b includes a latch unit for latching a data signal and a source output unit 143 including a DA conversion unit for converting a digital data signal into an analog data voltage, A source amplifier section 148 for amplifying and outputting the output data voltage, and a dummy source amplifier section 149 for compensating the data voltage.

The second data driver 140b outputs the data voltage to the right display area AAR corresponding to the edge bending area of the display panel. Therefore, the second data driver 140b compensates the data voltage to compensate for the area where the characteristic change of the device occurs due to the physical deformation of the display panel.

The second data driver 140b controls the dummy source amplifier 149 to compensate the data voltage. For example, the dummy source amplifier unit 149 may be implemented to have a fixed amplification factor to compensate for a change in the characteristics of the device based on experiments or to have a variable amplification factor based on an external control signal CS.

The external control signal CS may be supplied from a circuit section capable of sensing the banding characteristics of the timing control section and the display panel (such as the area where the characteristics of the device are changed due to banding, the banding area, the banding angle, etc.).

The third embodiment of the present invention can be applied when it is difficult to form a double-resistor string (R-String) in the data driver. As described above, a data voltage is output to the flat area of the display panel in the same manner as in the conventional method. On the other hand, a dummy source amplifier unit capable of individually adjusting the luminance is further provided in the edge bending area of the display panel, and the data voltage is compensated and output.

As shown in FIG. 11, the first data driver 140a and the second data driver 140b may be included in one data driver 140. FIG. The first data driver 140a is configured to output a data voltage to the first to i-th data lines DL1 to DLi arranged in a flat area of the display panel. The second data driver 140b is configured to output the data voltage to the jth to the nth data lines DLj to DLn arranged in the edge bending area of the display panel.

Although the data driver 140 includes the first data driver 140a and the second data driver 140b in the above description, the first data driver 140a and the second data driver 140b physically Or may be designed to separate.

On the other hand, in organic light emitting display devices based on organic light emitting diodes, problems caused by changes in the characteristics of the transistors are promptly displayed due to changes in brightness of the display panel, which greatly affects the reliability of the products and the completeness of the products.

The organic light emitting display device has an influence on the white balance when the luminance of red, green, and blue subpixels is changed to a different form from the previous one. As a result, . ≪ / RTI >

However, when the first to third embodiments of the present invention are applied to an organic light emitting display device, such an abnormal display state (Abnormal Display) can be reduced. In addition, the first to third embodiments of the present invention can improve the stability and reliability of the bar device, which can compensate the display panel in various ways when the display panel is bent or folded.

The first embodiment of the present invention adjusts (changes) the digital value of the data signal in response to the stress applied to the display panel. The second embodiment of the present invention adjusts (changes) the analog value of the data signal in response to the stress applied to the display panel. The third embodiment of the present invention adds a dummy source amplifier section and adjusts (changes) the data voltage in response to the stress applied to the display panel. In addition, the present invention may implement the compensation circuit portion by combining at least one of the first to third embodiments.

As described above, the present invention has an effect of preventing or improving a change in luminance or color, and improving the display quality by applying a compensation circuit portion capable of performing signal (or voltage) compensation corresponding to external stress that bends or folds the display panel . In addition, the present invention has the effect of enhancing the stability and reliability of the bar device which can compensate the display panel in various ways when the display panel is bent or folded.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the following claims rather than the detailed description. Also, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

110: image supply unit 120: timing control unit
130: scan driver 140:
145: gamma unit 150: display panel
180: power supply unit 160: external compensation unit
168: compensation coefficient changing section 149: dummy source amplifier section
FG: first gamma portion BG: second gamma portion

Claims (10)

A data driver driving the display panel; And
And a compensating circuit for compensating for the stress the device receives when the display panel is bent or folded. The method according to claim 1,
The compensation circuit section
And adjusts a digital value of a data signal transmitted to the data driver in response to the stress, adjusts an analog value of the data signal, or adjusts a data voltage output through an output terminal of the data driver. The method according to claim 1,
The compensation circuit section
A change in characteristics of the device according to the stress is received through a sensing transistor included in a sub-pixel of the display panel,
And extracts a compensation coefficient corresponding to a characteristic change of the device and adjusts a digital value of a data signal transmitted to the data driver based on the compensation coefficient. The method of claim 3,
The compensation circuit section
A display receiving a change in characteristics of the device from all the subpixels of the display panel or receiving a change in characteristics of the device from a subpixel positioned in a region where a characteristic change of the device occurs when the display panel is bent or collapsed, Device. The method according to claim 1,
The compensation circuit section
Wherein the gamma is adjusted only in a region where a characteristic change of the device occurs when the display panel is bent or folded. 6. The method of claim 5,
The compensation circuit section
And changes the gamma maximum voltage value based on a control signal provided from a circuit portion capable of sensing at least one of a region where a characteristic change of the device occurs, a bending region, and a bending angle when the display panel is bent or folded. The method according to claim 1,
The compensation circuit section
And a dummy source amplifier unit provided at an output terminal of the data driver for driving a region where a characteristic change of the device occurs when the display panel is bent or folded. 8. The method of claim 7,
The dummy source amplifier section
And a control circuit for controlling at least one of an area where a characteristic of the device is changed, a banding area and a bending angle when the display panel is bent or folded, This fluctuating display device. Driving a display panel;
Detecting a stress of the device when the display panel is bent or folded; And
And performing a compensating operation corresponding to a stress received by the device. 10. The method of claim 9,
The step of performing the compensating operation
And adjusting a digital value of a data signal transmitted to the data driver in response to the stress, adjusting an analog value of the data signal, or adjusting a data voltage outputted through an output terminal of the data driver.

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