KR101380500B1 - Light Emitting Display - Google Patents

Abstract

The present invention provides a display device including a plurality of sub pixels positioned on a substrate; A driver supplying scan signals, data signals, and power to the display unit; And a gamma conversion unit for converting the gamma of the data signal supplied to the driver, wherein the gamma conversion unit acquires and acquires a power value supplied to the display unit when displaying a specific image patterned in a section where the display unit is turned on or turned off. The present invention provides an organic light emitting display device that compares the power value with the data value included in the lookup table and lowers the gamma voltage when the power value is larger than the data value and increases the gamma voltage value when the power value is smaller than the data value. .

Organic light emitting display device, gamma voltage, cruise table

Description

Organic electroluminescent display device {Light Emitting Display}

1 is a schematic block diagram of an organic light emitting display device according to an embodiment of the present invention;

2 is an exemplary diagram of a subpixel circuit configuration;

3 is a schematic block diagram of a gamma conversion unit;

4 is an exemplary circuit diagram of an element circuit unit included in a voltage conversion block.

5 is an exemplary diagram of a resistor string supplied with a gamma voltage value.

DESCRIPTION OF THE REFERENCE NUMERALS

110: subpixel 120: display unit

130a: scan driver 130b: data driver

130c: power supply unit 140: gamma conversion unit

150: timing controller

The present invention relates to an organic light emitting display.

An organic electroluminescent device used in an organic electroluminescent display device is a self-luminous device in which a light emitting layer is formed between two electrodes.

The organic electroluminescent device has a top emission mode and a bottom emission mode depending on a direction in which light is emitted and a passive matrix type and an active matrix type Active Matrix).

Among the organic light emitting display devices, an organic light emitting display device using an active matrix type includes a transistor, a capacitor, and an organic light source positioned inside a subpixel when a scan signal and a data signal are supplied to a plurality of subpixels arranged in a matrix form on a display unit. The light emitting diode is driven to display an image.

Meanwhile, in the related art organic light emitting display device, a resistance string included in the gamma part is used to adjust the gamma of the R, G, and B image signals. In the technique using the resistor string, the gamma voltage is simply set to the reference point value by the resistor string, so the gamma voltage is always fixed to a specific value. Therefore, in such a technique, when the resistance value is adjusted, the gamma reference voltage is adjusted, and thus the brightness is adjusted.

However, since the gamma voltage is determined only by the set value and fixed to a specific value, the gamma voltage cannot be adjusted flexibly according to the deterioration degree of the organic material or the transistor driving the transistor. do.

An object of the present invention for solving the above problems is to improve the display quality by providing an organic light emitting display device that can automatically set the gamma voltage according to the state of the panel.

The present invention for solving the above problems, the display unit including a plurality of sub-pixels located on the substrate; A driver supplying scan signals, data signals, and power to the display unit; And a gamma conversion unit for converting the gamma of the data signal supplied to the driver, wherein the gamma conversion unit acquires and acquires a power value supplied to the display unit when displaying a specific image patterned in a section where the display unit is turned on or turned off. The present invention provides an organic light emitting display device that compares the power value with the data value included in the lookup table and lowers the gamma voltage when the power value is larger than the data value and increases the gamma voltage value when the power value is smaller than the data value. .

The lookup table may include a preset data value arranged such that the display unit displays an ideal image for each data signal.

The gamma conversion unit may include a gamma voltage storage unit, and the gamma voltage storage unit may be a nonvolatile storage unit that stores the gamma voltage value.

The gamma converter may include an analog to digital (AD) converter for converting a power value into a digital value, and a digital to analog (DA) converter for converting a gamma voltage value into an analog value.

The cruise table unit includes a decoder unit, and the decoder unit may generate an address so as to transfer a data value required by the gamma conversion unit among the data values arranged in the cruise table unit.

The gamma converter may include a gamma voltage controller, and the gamma voltage controller may correct an error of the gamma voltage value.

The gamma voltage storage unit may include a storage control unit, and the storage control unit may supply a control signal to the gamma voltage storage unit to control the gamma voltage value including reading, writing, and address.

일 수 있다.The AD conversion unit includes an element circuit unit, and the element circuit unit includes one or more resistors, amplifiers, and transistors to convert the power value supplied to the display unit into a voltage value and supply the AD value to the AD conversion unit. Node Vc

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The subpixels can include one or more capacitors, transistors, and organic light emitting diodes.

<Example 1>

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

Referring to FIG. 1, an organic light emitting display device according to an exemplary embodiment includes a panel that is a display unit 120 including a plurality of sub pixels 110 arranged in a matrix form on a substrate.

And a driver 130a, 130b, 130c for supplying scan signals, data signals, and power to the display unit 120. As illustrated, the drivers 130a, 130b, and 130c may be provided to the scan driver 130a for supplying the scan signal to the display 120 and the data driver 130b and the display 120 for supplying data signals to the display 120. It may be divided into a power driver 130c for supplying power.

And a gamma converter 140 for converting the gamma of the data signal supplied to the data driver 130b among the drivers 130a, 130b, and 130c. In particular, the gamma converter 140 acquires a power value EL_VDD supplied to the display 120 when the display 120 displays a specific image patterned in a section where the display 120 is turned on or turned off. In addition, the gamma conversion unit 140 compares the acquired power value EL_VDD with the data value of the lookup table included therein, and lowers the gamma voltage value when the power value EL_VDD is larger than the data value, and the power value EL_VDD. If smaller than this data value, a gamma voltage conversion unit for increasing the gamma voltage value is included.

The data signal RGB and gamma are supplied to the data driver 130b, and the control signal is supplied to the scan driver 130a, the data driver 130b, the power driver 130c, and the gamma converter 140. And a timing controller 150.

The timing controller 150 supplies control signals CS1, CS2, CS3, and CS4 to the scan driver 130a, the data driver 130b, the power driver 130c, and the gamma converter 140 to control them. Supply each.

Hereinafter, referring to FIG. 2, a description of the circuit configuration of the subpixel illustrated in FIG. 1 will be described in detail.

2 is an exemplary diagram of a subpixel circuit configuration.

However, the circuit configuration diagram of the subpixels illustrated in FIG. 2 is only an example of a circuit configuration for better understanding of the description, and the present disclosure is not limited thereto.

As illustrated in FIG. 2, the subpixel includes a switching transistor TFT1 having a gate connected to the scan line SCAN and a first electrode connected to the data line DATA in common. In addition, the driving transistor TFT2 includes a gate connected to the second electrode of the switching transistor TFT1 and a first electrode connected to the first power line VDD. In addition, the capacitor C may be connected between the gate of the driving transistor TFT2 and the first power line VDD. In addition, the organic light emitting diode D may include an organic light emitting diode D connected between the second electrode of the driving transistor TFT2 and the second power line GND.

Here, the organic light emitting diode D may be an organic light emitting diode in which the light emitting layer is formed of an organic material layer, but may also be an inorganic light emitting diode in which the light emitting layer is formed of an inorganic material layer.

In addition to the description of the structure of the organic light emitting diode (D), the organic light emitting diode (D) is common, such as a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL) and an electron injection layer (EIL) The organic light emitting layer (EML) is interposed between the film. In general, the common film is selectively formed between the first electrode (pixel electrode) and the cathode of the driving transistor TFT2 serving as the anode electrode.

On the other hand, the power wiring of each sub-pixel may be connected to a power supply so as to be distinguished from each other, and may receive independent voltages, that is, different voltages.

Hereinafter, the gamma converter shown in FIG. 1 will be described in more detail with reference to FIG. 3.

3 is a schematic block diagram of a gamma conversion unit.

As shown in FIG. 3, the gamma conversion unit 141 acquires power supplied to the display unit, and sets a gamma voltage value based on the power acquired from the voltage conversion block 141. To 146, and gamma voltage storage blocks 147 and 148 that store gamma voltage values set by the gamma voltage control blocks 142 to 146.

First, the analog to digital (AD) conversion unit 141 included in the voltage conversion block 141 obtains a power value EL_VDD from power supply wiring of a subpixel included in the display unit.

To this end, the voltage conversion block 141 includes not only the AD conversion unit 141 but also the device circuit unit, which will be described with reference to FIG. 4 below.

4 is an exemplary circuit diagram of an element circuit unit included in a voltage conversion block.

As shown in FIG. 4, the AD conversion unit included in the voltage conversion block includes an element circuit unit. Here, the device circuit unit includes one or more resistors R1, R2, R3, an amplifier OP, and a transistor TFT to convert the power value EL_VDD supplied to the display unit into a voltage value to convert the power value to the AD converter 141. Supply.

Here, the node Vc formed between the transistor TFT and the third resistor R3 to supply the voltage value supplied to the AD converter 141 may be represented by Equation 1 below.

Here, Vc is an amplifier that receives two inputs from the first resistor R1 connected to the first node and the second resistor R2 connected to the second node. It is determined by the values of the transistors TFT driven according to the output value of OP) and the third resistor R3 located at their voltage divider node.

In this way, the Vc value obtained from the display unit is converted into a digital value by the AD converter 141, and the AD converter 141 supplies this value to the gamma voltage control blocks 142 to 146.

Then, the comparator 144 included in the gamma voltage control blocks 142 to 146 is configured with the data value preset in the look-up table 143 included therein and the power supplied from the AD converter 141. Compare the value EL_VDD.

Here, the comparator 144 compares the data value set in the lookup table 143 with the power value EL_VDD supplied from the AD converter 141, and lowers the gamma voltage value when the power value EL_VDD is larger than the data value. If the power supply value EL_VDD is smaller than the data value, increase the gamma voltage value.

The lookup table unit 143 is a list of preset data values such that the display unit displays an ideal image for each data signal. That is, data corresponding to the target current value for each R, G, B data signal is stored.

The lookup table unit 143 may be linked with the decoder unit 142. The decoder unit 142 generates an address so as to transfer a data value required by the gamma conversion unit among the data values arranged in the lookup table unit 143. can do.

In this case, the address generated by the decoder 142 may be a patterned data signal mode (RGB mode) from the timing controller 150 to calculate a corresponding data value when the display unit expresses a specific patterned image. A status signal may also be supplied.

However, this is possible even in the present display state, not necessarily in the patterned display state, but it is more advantageous to acquire the power value supplied to the display portion when representing the specific patterned image.

Accordingly, the value compared through the comparator 144 compares the power value of the current display unit with the target current value and supplies the difference value to the gamma voltage controller 145. In this case, the difference value includes a sign (+/-), and the power supply value may be a current or voltage value.

Subsequently, the gamma voltage controller 145 adjusts the gamma voltage value based on the difference value supplied from the comparator 144. Here, when the gamma voltage controller 145 previously acquires the power value from the display unit, the difference between the power value of the display unit and the data value of the lookup table may not be exactly matched due to the difference in resolution, thereby correcting the error of the gamma voltage value. You may.

Accordingly, the gamma voltage storage unit 147 adjusts the gamma voltage value such that the value output from the comparator 144 is minimum, and supplies the final value to the digital to analog (DA) conversion unit 146 and the gamma voltage storage unit. Save to (147).

Subsequently, when the gamma voltage storage unit 147 stores the gamma voltage value set by the gamma voltage control unit 145, the gamma voltage storage unit 147 may perform read, write, and address control through the storage control unit 148. That is, the storage controller 148 may supply a control signal to the gamma voltage storage unit 147 to perform input / output control between the gamma voltage storage unit 147 and the gamma voltage control unit 148.

Here, it is advantageous that the gamma voltage storage unit 147 uses a nonvolatile storage unit. Accordingly, as illustrated, a read only memory (ROM) is an example. This is to maintain the stored value even if the display device is turned off after the gamma voltage storage unit 147 stores the gamma voltage value.

Meanwhile, the gamma voltage value adjusted as described above is supplied to the voltage terminal of the resistor string R string to adjust the gamma reference voltage, which will be described with reference to FIG. 5 below.

5 is an exemplary diagram of a resistor string to which a gamma voltage value is supplied.

As shown in FIG. 5, the gamma voltage value adjusted according to the state of the display unit is supplied to voltage terminals R_GVDD, G_GVDD, and B_GVDD of independent gamma for each of R, G, and B.

That is, the gamma voltage value adjusted through the gamma converter is supplied to the voltage terminals R_GVDD, G_GVDD, and B_GVDD of the resistance strings of R, G, and B, respectively, to provide gamma reference voltages R_Ref, G_Ref, and B_Ref suitable for the display state. It can be created automatically.

The driving method according to the present invention described above is briefly described as follows.

First, a power value of the display unit is detected and converted into a voltage.

Thereafter, the converted voltage value is converted into a digital value through the AD converter.

Then, the converted digital value is compared with the data value of the lookup table.

Thereafter, if the digital value is larger than the data value, the gamma voltage value is lowered. If the digital value is smaller than the data value, the gamma voltage value is increased. The set gamma voltage value is stored in the ROM, which is a gamma voltage storage unit.

Thereafter, the digital gamma voltage value is converted into an analog gamma voltage value through the DA converter.

Thereafter, the above steps are repeated from the beginning until the power value is within a desired range, that is, within the data value range of the lookup table.

On the other hand, when driving in this way it is possible to adjust the brightness of the display unit, which is performed at the following two points.

First, when the display device is driven for the first time, it can be seen that luminance variations between panels may appear even under the same driving conditions due to manufacturing process variations. Therefore, the automatic brightness adjustment at the first driving minimizes the R, G, and B brightness variations between panels, and automatically adjusts the color balance.

Second, when the display device is turned on or off, it is noted that there may be a difference in the degree of luminance reduction with time because R, G, and B lifespans are different due to the material characteristics of the organic light emitting diode. Therefore, it is not possible to display a specific patterned image for brightness control during image display time. Therefore, when the display is turned on or off, the brightness is adjusted and the value is stored in the ROM so that the difference in the lifespan of R, G, B can be avoided. Correct or prevent color change accordingly.

The present invention not only improves the disadvantages of the prior art in which the gamma voltage value is fixed to a specific voltage value, but also makes it possible to automatically set the gamma voltage value by referring to the state of the display unit to perform more efficient gamma correction.

Accordingly, the present invention provides an organic light emitting display device capable of automatically setting a gamma voltage according to a panel state, thereby improving display quality.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments thereof, 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 equivalents thereof should be construed as being included within the scope of the present invention.

As described above, the present invention provides an organic light emitting display device capable of automatically setting a gamma voltage according to a panel state, thereby improving display quality.

Claims (9)

A display including a plurality of sub-pixels located on a substrate; A driver supplying a scan signal, a data signal, and power to the display unit; A gamma converter configured to convert a gamma of the data signal supplied to the driver, The gamma conversion unit, When the display unit displays a specific image patterned in a section turned on or turned off, the power is supplied to the display unit, and the obtained power value is compared with the data value of the cruise table included therein. And a gamma voltage value when the value is greater than the data value, and a gamma voltage value when the power value is less than the data value. The method according to claim 1, The cruise table unit, An organic light emitting display device in which data values are arranged such that the display unit displays an ideal image for each data signal. The method according to claim 1, The gamma conversion unit includes a gamma voltage storage unit, The gamma voltage storage unit is a non-volatile storage unit for storing the gamma voltage value. The method according to claim 1, The gamma conversion unit, And an analog to digital (AD) converter for converting the power value into a digital value and a digital to analog (DA) converter for converting the gamma voltage value to an analog value. The method according to claim 1, The cruise table unit includes a decoder unit, And the decoder unit generates an address so as to transfer a data value requested by the gamma conversion unit among the data values arranged in the lookup table. The method according to claim 1, The gamma converter includes a gamma voltage controller, And the gamma voltage control unit corrects an error of the gamma voltage value. The method of claim 3, The gamma voltage storage unit includes a storage control unit, And the storage controller supplies a control signal to the gamma voltage storage unit to control the gamma voltage value including reading, writing, and address. 5. The method of claim 4, The AD conversion unit includes a device circuit unit, The device circuit unit includes one or more resistors, amplifiers, and transistors to convert the power value supplied to the display unit into the voltage value, and supply the converted voltage value to the AD conversion unit. The node Vc for converting the power value into the voltage value

Phosphorescent organic light emitting display device. The method according to claim 1, The subpixels include one or more capacitors, transistors, and organic light emitting diodes.

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