KR101338793B1 - Electro-Luminescence Display Device and Driving Method Thereof - Google Patents

Abstract

The present invention provides an electroluminescent display device suitable for displaying an image having a constant luminance characteristic even when the temperature changes.

An EL display panel includes a panel in which pixels including diodes are connected to corresponding gate lines and corresponding data lines in respective regions divided by gate lines and data lines. A driver for driving pixels on the panel by scanning the voltage generator and the voltage generator and supplying the high and low potential driving voltages required for the pixels on the panel to the panel; And a temperature sensitive impedance element connected to any one of the lines for transmitting, so that any one of a current and a voltage to be supplied to the panel is adjusted according to the temperature on the panel.

AMOLED, deterioration, LED, temperature, compensation, luminance, data, gamma, resistance.

Description

Electro-Luminescence Display Device and Driving Method Thereof}

1 is a block diagram schematically illustrating an organic light emitting display device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram illustrating a pixel on the organic electroluminescent panel of FIG. 1.

3 is a block diagram schematically illustrating an organic light emitting display device according to a second embodiment of the present invention.

4 is a block diagram schematically illustrating an organic light emitting display device according to a third embodiment of the present invention.

5 is a block diagram schematically illustrating an organic light emitting display device according to another exemplary embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

10 organic electroluminescent panel 12 gate driver

14: Data driver 16: Timing controller

18: voltage generator 20,30: temperature sensitive resistor

40: temperature detector 42: compensation rate determination unit

44: adaptive gamma voltage generator 50: data compensation unit

ELD: Electroluminescent Diode Cst: Storage Capacitor

MT1, MT2: first and second thin film transistors.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel display for displaying an image, and more particularly, to a display device for displaying an image by adjusting an amount of light of an electroluminescent diode and a driving method thereof.

A conventional flat panel display device displays an image on a flat panel such as a liquid crystal panel, an electro-luminescence panel, and a plasma display panel. Such a flat panel display device can be made slim and lightweight, and it is easy to implement a large screen. Accordingly, the flat panel display device has been used as a display device of a computer system, a television receiver, and a telecommunication device in place of a conventional cathode ray tube (CTS) display device.

Among the flat panel displays, the electroluminescent display is spotlighted in that it has a wide viewing angle and does not require a separate light source. This is because the electroluminescent panel used in the flat panel display device includes an electroluminescent diode which generates an amount of light according to the voltage or current of the pixel data signal.

However, the electroluminescent diode generates heat together with radiation of light to raise the temperature in the electroluminescent panel. The increase in temperature in the electroluminescent panel degrades the light emitting characteristics of the electroluminescent diode. As a result, the EL emits a changed amount of light with respect to the pixel data signal of the same voltage level or the same amount of current. For this reason, the brightness of the image displayed on the electroluminescent panel is changed. As a result, it was not possible to provide an image of good quality in a conventional electroluminescent display.

Accordingly, an object of the present invention is to provide an electroluminescent display device and a driving method thereof suitable for displaying an image having a constant luminance characteristic even when the temperature changes.

Another object of the present invention is to provide an electroluminescent display and a driving method thereof suitable for displaying a high quality image even when the temperature changes.

In the electroluminescent display according to the embodiment of the present invention for achieving the above object, a gate line and a corresponding data corresponding to a pixel including diodes in respective regions divided by gate lines and data lines A panel configured to be connected to a line; a driver configured to scan the gate lines and the data lines to drive pixels on the panel; a voltage generator and a voltage generator configured to supply high and low potential driving voltages necessary for pixels on the panel; And a temperature sensitive impedance element connected to any one of the lines for delivering the high and low potential driving voltages to the panel, such that any of the current and voltage to be supplied to the panel is adjusted according to the temperature on the panel. It is provided.

In another exemplary embodiment, an EL display device includes a pixel including diodes connected to a corresponding gate line and a corresponding data line in each of the regions divided by the gate lines and the data lines. In response to the panel video data, a driver for scanning the gate lines and the data lines to drive the pixels on the panel; a temperature sensing unit sensing a temperature on the panel; and a temperature sensing unit based on a sensed temperature from the temperature sensing unit. And a data compensator for compensating grayscale values of video data to be supplied to the driver.

According to another exemplary embodiment, an EL display device includes a pixel including diodes connected to a corresponding gate line and a corresponding data line in each of the regions divided by the gate lines and the data lines. A variable gamma voltage generator for generating a set of panel gamma voltages. The pixel driving signal is converted into video data using the gamma voltage set, and the gate lines and the data lines are scanned to output the pixel driving signal to the pixel on the panel. And a compensation rate determining unit for causing the variable gamma voltage generator to change a level range of the gamma voltage set based on a temperature sensing unit for sensing a temperature on the panel and a sensed temperature from the temperature sensing unit.

According to another aspect of the present invention, there is provided a method of driving an EL display device, the method comprising: driving pixels having respective diodes on a panel in response to video data; Compensating for the gradation value of the video data based on the value.

According to an embodiment of the present disclosure, a method of driving an EL display device may include generating a gamma voltage set, converting video data into a pixel driving signal using the gamma voltage set, and forming a light emitting diode on the panel. Supplying the pixel drive signal to the pixels; sensing a temperature on the panel and changing a level range of the gamma voltage set based on the sensed temperature.

Other objects, other features, and other advantages of the present invention will become apparent from the detailed description of the embodiments with reference to the attached drawings.

Best Mode for Carrying Out the Invention Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram schematically illustrating an EL display device according to a first embodiment of the present invention. 1, a light emitting display device according to a first embodiment of the present invention includes a gate driver 12 for driving a plurality of gate lines (or scan lines) (GL1 ~ GLn) on the light emitting panel 10 ; And a data driver 14 driving a plurality of data lines (or source lines) DL1 to DLm on the electroluminescent panel 10. The EL panel 10 is divided into a plurality of unit regions by the plurality of gate lines GL1 to GLn and the plurality of data lines DL1 to DLm that cross each other. Light emitting pixels ELP are formed in each of the unit regions.

Each of the light emitting pixels on the electroluminescent panel 10 includes an electroluminescent diode ELD connected in series between a high potential supply voltage line VDD and a low potential supply voltage line VSS, as shown in FIG. 2. A first thin film transistor MT1; A storage capacitor Cst connected between a control node CN and the low potential supply voltage line VSS; And a second thin film transistor MT2 connected between the data line DL, the gate line GL, and the control node CN. The second thin film transistor MT2 is turned on when the gate signal is enabled with a specific logic (for example, high logic) on the gate line GL, and the data line DL and the second thin film transistor MT2 are turned on. The current path between the control nodes CN is formed. In this case, the pixel data signal on the data line DL is charged in the storage capacitor Cst via the second thin film transistor MT2 and the charging node CN. The voltage of the pixel data signal charged in the storage capacitor Cst is maintained until the second thin film transistor MT2 is turned on again. The first thin film transistor MT1 adjusts the amount of current flowing in the electroluminescent diode ELD in response to a voltage on the control node CN (that is, a voltage charged in the storage capacitor Cst). In other words, the first thin film transistor MT1 has an amount of current corresponding to the voltage level on the control node CN from the high potential supply voltage line VDD to the electroluminescent diode ELD, and It flows toward the low potential supply voltage line VSS via its source and drain terminals. Then, the ELD emits light in an amount corresponding to the amount of current determined by the first thin film transistor MT1 so that the pixel corresponding to the gray level of the pixel data is displayed.

The gate driver 12 has a plurality of gate lines GL1 to GLn on the electroluminescent panel 10 sequentially every frame (period of one vertical synchronizing signal), for example. Enable periods). In order to sequentially enable the plurality of gate lines GL1 to GLn, the gate driver 12 responds to a gate control signal GCS. The gate control signal GCS includes a gate start pulse generated at the time of the frame and at least one clock signal swinging at a period of the horizontal synchronization signal.

Whenever any one of the plurality of gate lines GL1 to GLn is enabled (i.e., every period of a horizontal synchronization signal), the data driver 14 outputs one line of pixel data signals to the electroluminescent panel ( 10) to the plurality of data lines DL1 to DLm on it. To this end, the data driver 14 inputs one line of pixel data streams in response to the data control signal DCS. One line of pixel data is converted into an analog pixel data signal in an analog form by the data driver 14. The converted pixel data signal is supplied to the plurality of data lines DL1 to DLm on the electroluminescent panel 10.

The EL display device may further include a timing controller 16 controlling driving timings of the gate driver 12 and the data driver; And a voltage generator 18 for generating a supply voltage required for driving the light emitting pixels on the electroluminescent panel. The timing controller 16 receives the above gate control signal GCS and data control signal using the synchronization signals SYNC from an external system (e.g., the computer system is an image demodulation module of a graphics module or television receiver). Occurs. Further, the timing controller 16 can input frame-based pixel data (VDf) from an external system. The pixel data in the frame unit is rearranged to the pixel data VDl by one line. The rearranged pixel data VDl for each line is supplied to the data driver 14.

The voltage generator 18 generates a high potential supply voltage VDD and a low potential supply voltage VSS required for driving the light emitting pixels on the electroluminescent panel 10. These high potential supply voltages VDD and low potential supply voltages VSS are commonly supplied to light emitting pixels on the electroluminescent panel 10.

The light emitting elements on the electroluminescent panel 10 driven by the high potential and low potential supply voltages VDD and VSS from the voltage generator 18 are selectively in line by the gate driver 12. Able to be. In the enabled period, the light emitting devices charge the pixel data signal supplied from the data driver 14 via corresponding data lines DL1 to DLm. Each of the light emitting pixels emits an amount of light corresponding to a charged voltage for one frame period to display an image.

In addition, the electroluminescent display of FIG. 1 further includes a temperature sensitive resistor 20 connected between the voltage generator 18 and the low potential supply voltage line VSS on the electroluminescent panel 10. Equipped. The temperature sensitive resistor 20 has a resistance value that varies with the temperature of the electroluminescent panel 10 to raise or lower the low potential level of the low potential supply voltage line VSS of the electroluminescent panel 10. Let's do it. For example, when the temperature of the electroluminescent panel 10 rises, the temperature sensitive resistor 20 has a low resistance value to lower the voltage level on the low potential supply voltage line VSS. Since the voltage difference between both ends of the series circuit of the ELD and the first thin film transistor MT1 shown in FIG. 2 increases, the amount of current flowing through the ELD increases. The increased amount of current compensates for the light emission characteristics of the ELD degraded by the temperature rise of the EL panel 10. Accordingly, the ELD maintains a constant light emission characteristic with respect to the pixel data signal even when the temperature of the EL panel 10 rises. As a result, the brightness of the image displayed on the electroluminescent panel 10 can be kept constant even if the temperature of the electroluminescent panel rises. As the temperature sensitive resistor 20, a thermistor having negative resistance may be used. In order to respond sensitively to the temperature of the electroluminescent panel 10, the temperature sensitive resistor 20 is provided on the electroluminescent panel 10. Preferably, the temperature sensitive resistor 20 is formed on the electroluminescent panel 10 together with the electroluminescent diode ELD and the thin film transistors MT1 and MT2.

3 is a block diagram schematically illustrating an EL display device according to a second embodiment of the present invention. The electroluminescent display of FIG. 3 is provided on the electroluminescent panel 10 instead of the temperature sensitive resistor 20 connected between the low potential supply voltage line VSS on the electroluminescent panel 10 and the voltage generator 18. Except for providing a temperature sensitive resistor 30 between the high potential supply voltage line (VDD) and the voltage generating unit 18 has the same configuration as the electroluminescent display of FIG. Components of FIG. 3 having the same name, function, and effect as those shown in FIG. 1 will be referred to by the same reference numerals, and operation and effect on them will be readily apparent to those skilled in the art from the description of FIG. Will be omitted.

In FIG. 3, the temperature sensitive resistor 30 has a resistance value that varies with the temperature of the electroluminescent panel 10 so as to have a high potential on the high potential supply voltage line VDD of the electroluminescent panel 10. Raise or lower the level of the supply voltage. For example, when the temperature of the electroluminescent panel 10 rises, the temperature sensitive resistor 30 has a low resistance value, causing the voltage level on the high potential supply voltage line VDD to increase. The voltage difference across the series circuit of the ELD and the first thin film transistor MT1 shown in FIG. 2 increases. Therefore, the amount of current flowing through the ELD increases. The increased amount of current compensates for the light emission characteristics of the ELD degraded by the temperature rise of the EL panel 10. Accordingly, the ELD maintains a constant light emission characteristic with respect to the pixel data signal even when the temperature of the EL panel 10 rises. As a result, the brightness of the image displayed on the electroluminescent panel 10 can be kept constant even if the temperature of the electroluminescent panel rises. As the temperature sensitive resistor 30, a thermistor having negative resistance may be used. In order to respond sensitively to the temperature of the electroluminescent panel 10, the temperature sensitive resistor 30 is provided on the electroluminescent panel 10. Preferably, the temperature sensitive resistor 30 is formed on the EL panel 10 together with the ELD and the thin film transistors MT1 and MT2.

4 is a block diagram schematically illustrating an EL display device according to a third embodiment of the present invention. In the electroluminescent display of FIG. 4, a temperature detector 40 is connected between the low potential supply voltage line VSS and the voltage generator 18 on the electroluminescent panel 10 instead of the temperature sensitive resistor 20. The same as that of the electroluminescent display of FIG. 1 except for including the compensation factor determining unit 42 and the adaptive gamma voltage generator 44 connected in series between the temperature detector 40 and the data driver 14. Has a configuration. Components of FIG. 4 having the same names, functions, and effects as those shown in FIG. 1 will be referred to by the same reference numerals, and operation and effects on them will be readily apparent to those skilled in the art from the description of FIG. Will be omitted.

The temperature detector 40 senses the temperature of the electroluminescent panel 10 by the amount of current flowing from the low potential supply voltage line VSS on the electroluminescent panel 10 toward the voltage generator 18. To this end, the temperature detector 40 generates a temperature detection signal whose voltage level changes according to the amount of current flowing from the low potential supply voltage line VSS toward the voltage generator 18.

The compensation rate detector 42 determines a compensation rate of pixel data (or a pixel data signal) in response to the temperature detection signal from the temperature detector 40. The compensation rate determiner 42 compares the temperature detection signal with at least two reference voltages and detects which of at least two error ranges preset. The compensation rate determiner 42 supplies the error range identification code for the detected error range to the adaptive gamma voltage generator 44 as compensation rate data of the pixel data (or pixel data signal).

The adaptive gamma voltage generator 44 may select any one of at least two gamma voltage signal sets having different voltage level ranges according to a logic value of the compensation rate data from the compensation factor detector 42. To feed. The gamma voltage signal set in which the level range is changed in this way causes the gray levels of the pixel data signal to be adjusted high or low when the pixel data is converted into the pixel data signal by the data driver 14. Since the deteriorated light emission characteristic of the ELD in FIG. 2 is compensated by adjusting gray levels of the pixel data signal, the light emission characteristic of the ELD with respect to the pixel data is decreased. Even if the temperature of the electroluminescent panel 10 changes, it is kept constant. Accordingly, the luminance of the image displayed on the electroluminescent panel 10 may be maintained even when the temperature of the electroluminescent panel rises. In order to generate the gamma voltage signal set in which the level range is different, the adaptive gamma voltage generator 44 may include a memory having a look-up table (not shown) including at least two gamma voltage data sets. And a digital-to-analog conversion array (not shown) for converting a set of gamma voltage data output from the memory into gamma voltage signals in analog form. The memory reads the gamma voltage data set on the look-up table corresponding to the logic value of the compensation rate data and supplies the read gamma voltage data set to the digital-analog conversion array. In another aspect, the adaptive gamma voltage generator comprises at least two gamma voltage generators each generating a set of gamma voltage signals of different voltage level ranges and at least two gamma from these gamma voltage generators in response to the compensation rate data. A selector may be provided to allow voltage signal sets to be selectively supplied to the data driver 14.

5 is a block diagram schematically illustrating an EL display device according to a fourth embodiment of the present invention. In the electroluminescent display of FIG. 5, the data driver 14, the timing controller 16, and the compensation rate determination are instead of the adaptive gamma voltage generator 44 connected between the compensation rate determination unit 42 and the data driver 14. It has the same configuration as the electroluminescent display of FIG. 4 except for providing a data compensator 50 connected between the sections 42. Components of FIG. 5 having the same names, functions, and effects as those shown in FIG. 4 will be referred to by the same reference numerals, and operation and effects on them will be readily apparent to those skilled in the art from the description of FIG. 4. Will be omitted.

The data compensator 50 is supplied from the timing controller 16 to the data driver 14 by a logic value of the compensation rate data from the compensation rate detection unit 42 or in proportion to the logic value of the compensation rate data. The gradation value of the acquired pixel data is corrected to be higher or lower. The pixel data whose gradation value is corrected according to the logic value of the compensation rate data causes the deteriorated light emission characteristic of the ELD in FIG. 2 to be compensated. Therefore, the light emission characteristic of the ELD with respect to the pixel data from the timing controller 16 remains constant even if the temperature of the EL panel 10 changes. Accordingly, the luminance of the image displayed on the electroluminescent panel 10 may be maintained even when the temperature of the electroluminescent panel rises. To compensate for the pixel data, The data compensator 50 adds the pixel data from the timing controller 16 and the compensation rate data from the compensation rate determiner 42 and supplies the added pixel data to the data driver 14. An adder (not shown) may be included. In another form, the data compensator 50 may further include a look-up table in which values are stored in proportion to a logical value of the compensation rate data from the compensation rate determiner 42. In this case, the look-up table supplies the adder with the second compensation rate data on the storage area corresponding to the logical value of the compensation rate data from the compensation rate determining unit 42.

As described above, in the electroluminescent display device according to the present invention, as the temperature of the electroluminescent panel rises, the supply voltage supplied to the electroluminescent diode (ELD) on the electroluminescent panel is increased to increase the electroluminescent diode (ELD). The amount of current flowing in increases. The increased amount of current compensates for the light emission characteristics of the ELD degraded by the temperature rise of the EL panel 10. Accordingly, the ELD maintains a constant light emission characteristic with respect to the pixel data signal even when the temperature of the EL panel 10 rises. As a result, the brightness of the image displayed on the electroluminescent panel 10 can be kept constant even if the temperature of the electroluminescent panel rises. As a result, the electroluminescent display device according to the present invention can provide a good image even if the temperature of the electroluminescent panel changes.

In addition, the electroluminescent display device according to the present invention, as the temperature of the electroluminescent panel rises, the gradation value of the pixel data or the gamma voltage signals is increased so that deteriorated light emission of the electroluminescent diode (ELD) on the electroluminescent panel is achieved. The property may be rewarded. As a result, the light emission characteristic of the ELD with respect to the pixel data is kept constant even when the temperature of the EL panel 10 changes. Accordingly, the luminance of the image displayed on the electroluminescent panel 10 may be maintained even when the temperature of the electroluminescent panel rises. As a result, the electroluminescent display device according to the present invention can provide a good image even if the temperature of the electroluminescent panel changes.

As described above, the present invention has been described with reference to the embodiments shown in FIGS. 1 to 5, but a person having ordinary knowledge in the technical field to which the present invention belongs does not depart from the spirit and scope of the present invention. It will be apparent that various modifications, changes and equivalent other embodiments are possible. Therefore, the technical scope and features of the present invention should not be limited to the description of the embodiments but should be set by the matters described in the appended claims.

Claims (9)

In each of the regions divided by the gate lines and the data lines, a panel provided such that a pixel including diodes is connected to a corresponding gate line and a corresponding data line. A driver configured to scan the gate lines and the data lines to drive pixels on the panel A voltage generator supplying high potential and low potential driving voltages to the pixels on the panel; A temperature response that is connected to either of the lines for transferring the high and low potential drive voltages from the voltage generator to the panel so that any one of the current and voltage to be supplied to the panel is adjusted according to the temperature on the panel An electroluminescent display device comprising a type impedance element. The method of claim 1, And the temperature sensitive impedance element is connected to a transmission line of the high potential driving voltage. The method of claim 2, And the temperature sensitive impedance element has a negative resistance characteristic. The method of claim 1, And the temperature sensitive impedance element is connected to a transmission line of the low potential driving voltage. 5. The method of claim 4, And the temperature sensitive impedance element has an impedance characteristic that increases with temperature. delete In each of the regions divided by the gate lines and the data lines, a panel provided such that a pixel including diodes is connected to a corresponding gate line and a corresponding data line. Variable gamma voltage generator for generating gamma voltage set A driving unit converts the video data into a pixel driving signal using the gamma voltage set, scans the gate lines and the data lines, and supplies the pixel driving signal to the pixels on the panel. A temperature sensor for sensing a temperature on the panel; And a compensation rate determiner configured to cause the variable gamma voltage generator to change a level range of the gamma voltage set based on the sensed temperature from the temperature detector. delete Generating Gamma Voltage Set Converting the video data into a pixel driving signal using the gamma voltage set, and supplying the pixel driving signal to pixels formed on the panel with light emitting diodes, respectively. Sensing temperature on the panel; and And changing a level range of the gamma voltage set based on the sensed temperature.

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