KR102640245B1 - Method for compensating data of the Organic light emitting diode display device - Google Patents

Abstract

The present invention relates to a data compensation method suitable for an ultra-high-resolution organic light-emitting diode display, wherein m? A data compensation method for an organic light emitting diode display device having pixels, comprising: dividing a plurality of gate lines among the n gate lines into one block into a plurality of blocks; A step of sequentially detecting changes in the electrical characteristics of the driving transistors of the block by simultaneously applying scan pulses to all gate lines of the block and simultaneously applying a sensing control signal to all sensing control lines of the block, sequentially block by block. ; In addition, it includes a step of compensating data on a block basis based on the amount of change in electrical characteristics of the detected driving transistors of each block.

Description

{Method for compensating data of the Organic light emitting diode display device}

The present invention relates to organic light emitting diode displays, and more particularly to a data compensation method for ultra-high resolution organic light emitting diode displays.

Recently, with the development of multimedia, the importance of flat panel display devices is increasing. In response to this, flat panel displays such as liquid crystal displays, plasma displays, and organic light emitting displays are being commercialized.

Among these flat panel displays, organic light-emitting diode (OLED) displays are self-luminous devices that emit light through an organic light-emitting layer by recombination of electrons and holes. They have high brightness, low driving voltage, high-speed response speed, can be made into ultra-thin films, and have a wide viewing angle. There are no problems with this, so it is attracting attention as a next-generation flat panel display device.

The organic light emitting diode display device consists of red (R), green (G), and blue (B) sub-pixels as one unit pixel, and displays various colors through the three sub-pixels. Displays one image composed of .

Each of the plurality of subpixels constituting the OLED display device includes an OLED element composed of an anode and a cathode and an organic light-emitting layer between them, and a pixel circuit that independently drives the OLED element.

The pixel circuit includes a switching transistor that supplies a data voltage to charge a storage capacitor with a voltage corresponding to the data voltage, and a driving transistor that controls current according to the voltage charged in the storage capacitor and supplies it to the OLED element. And the OLED device generates light proportional to the current.

In such organic light emitting diode display devices, there is a problem in that the desired grayscale cannot be realized due to differences in the electrical characteristics (threshold voltage, mobility) of the driving transistors between pixels due to process deviations or changes over time.

To solve this problem, a compensation method is known that senses deviations in the electrical characteristics (threshold voltage, mobility) of the driving transistor and corrects input data according to the sensed values.

In this way, a separate sensing transistor is further required to sense deviations in the electrical characteristics (threshold voltage, mobility) of the driving transistor.

The sensing method for extracting the deviation of the electrical characteristics (threshold voltage, mobility) of the driving transistor is to operate the driving transistor in a source follower method and then change the source voltage (Vs) of the driving transistor to the sensing voltage. The input is received, and the amount of change in the electrical characteristics (threshold voltage, mobility) of the driving transistor is detected based on the sensing voltage. The amount of change in the threshold voltage of the driving transistor is determined according to the size of the sensing voltage, and an offset value for data compensation is obtained through this. In this sensing method, the voltage (Vgs) between the gate and source of the driving transistor operated in the source follower method reaches the saturation state (i.e., the current between the drain and source of the driving transistor becomes zero). Sensing operation is performed after this.

Therefore, the capacity of the storage capacitor is very important.

However, in ultra-high resolution organic light emitting diode displays, the unit pixel size becomes very small, and the capacity of the storage capacitor is reduced. As the capacity of the storage capacitor is reduced in this way, it becomes difficult to compensate for input data based on the above-mentioned sensing method in an ultra-high-resolution organic light emitting diode display device.

Additionally, in the case of camera compensation, the specifications required for the corresponding camera are very high and the processing data is enormous, making equipment configuration and pixel-level compensation difficult.

In addition, a circuit external compensation method for ultra-high resolution display devices is currently in short supply.

The present invention is intended to solve this problem and provides a data compensation method for an organic light emitting display device that detects the amount of change in electrical characteristics (threshold voltage, mobility) of the driving transistor for each pixel block and compensates for the data on a block basis. The purpose is to provide.

The data compensation method of the organic light-emitting diode display device according to the present invention for achieving the above object is formed in the intersection area of m data lines, k sensing lines, n gate lines, and j sensing control lines. A data compensation method for an organic light emitting diode display device having m×n pixels, comprising: dividing a plurality of gate lines among the n gate lines into one block into a plurality of blocks; A step of sequentially detecting changes in the electrical characteristics of the driving transistors of the block by simultaneously applying scan pulses to all gate lines of the block and simultaneously applying a sensing control signal to all sensing control lines of the block, sequentially block by block. ; In addition, it is characterized by including a step of compensating data on a block basis based on the amount of change in electrical characteristics of the detected driving transistors of each block.

Here, before detecting the amount of change in the electrical characteristics of the driving transistors of the block, the method further includes applying a scan pulse to all gate lines of the block simultaneously and initializing the sensing capacitor of the block by an initialization control signal. do.

Each pixel includes a switching transistor controlled by the scan pulse of the corresponding gate line to switch between the corresponding data line and the first node (N1), a gate terminal connected to the first node, and a source terminal connected to the second node. A driving transistor is connected, the drain terminal of which is connected to a first driving power source to control the current flowing through the organic light emitting diode by the voltage between the first and second nodes, and the drain terminal is connected between the second node and the second driving power source. The organic light emitting diode, a sensing transistor that is controlled by a sensing control signal applied to the corresponding sensing control line to detect the threshold voltage of the driving transistor, and a storage capacitor connected between the first and second nodes, , It is characterized by simultaneously applying a scan pulse to all switching transistors of the block and simultaneously applying a sensing control signal to all sensing transistors of the block, thereby detecting the amount of change in electrical characteristics of the driving transistors of the block.

An initialization switch that switches the current flow between the initialization voltage input terminal and the corresponding sensing line in response to the initialization control signal. It is characterized in that it further includes a sampling switch that outputs the source voltage of the driving transistor as a sensing voltage in response to a sampling control signal during sensing operation.

A scan pulse is applied simultaneously to all gate lines of the block, and a sensing control signal is simultaneously applied to all sensing control lines of the block, and the amount of change in the electrical characteristics of the driving transistors of the block is detected sequentially in block units. The step is characterized in that it proceeds in a turn-off period of the organic light emitting diode display device.

The step of dividing a plurality of gate lines among the n gate lines into one block is characterized by shifting the gate line designated for the block in the next turn-off period of the organic light emitting diode display.

The data compensation method of the organic light emitting diode display device according to the present invention having the above features has the following effects.

That is, in the present invention, the amount of change in electrical characteristics (threshold voltage, mobility) of the driving transistor is detected for each block.

Therefore, in the ultra-high resolution organic light emitting diode display device, even though the unit pixel size becomes very small and the capacity of the storage capacitor is reduced, the storage capacitance (Cst) of each block increases, so the electrical characteristics of the driving transistor ( Threshold voltage, mobility) changes can be detected, and data can be compensated on a block basis.

1 is a block diagram of an organic light emitting display device equipped with a compensation device according to an embodiment of the present invention.
Figure 2 is a configuration diagram of a pixel array formed in a display panel according to an embodiment of the present invention.
3 is a waveform diagram during a sensing operation of an organic light emitting diode display device according to an embodiment of the present invention.
Figure 4 is a block diagram illustrating a sensing method of an organic light emitting diode display device according to an embodiment of the present invention.

The data compensation method of the organic light emitting diode display device according to the present invention having the above features will be described in more detail with reference to the attached drawings as follows.

FIG. 1 is a block diagram of an organic light emitting display device equipped with a compensation device according to an embodiment of the present invention, and FIG. 2 shows a pixel array formed in a display panel according to an embodiment of the present invention.

As shown in FIG. 1, an organic light emitting display device equipped with a compensation device according to an embodiment of the present invention includes a display panel 116, a gate driving circuit 118, a data driving circuit 120, and a timing controller 124. ) can be provided.

The display panel 116 includes m data lines (D1 to Dm) corresponding to each other in one-to-one correspondence to form m pairs, k sensing lines (S1 to Sk), n gate lines (G1 to Gn), and It may be provided with m-n pixels 122 formed in the intersection area of j sensing control lines (SC1 to SCj). In this display panel 116, signal wires for supplying the first driving power (Vdd) and the second driving power (Vss) to each pixel 122 may be formed. Here, the first driving power source (Vdd) and the second driving power source (Vss) may be generated from a high potential driving voltage source (VDD) and a low potential driving voltage source (VSS), respectively.

The gate driving circuit 118 may generate a scan pulse SP in response to the gate control signal GDC from the timing controller 124 and sequentially supply the scan pulse SP to the gate lines G1 to Gn. The gate driving circuit 118 can be controlled by the timing controller 124 to output a sensing control signal (SCS), and the sensing switch in each pixel can be controlled by the sensing control signal (SCS).

Although the gate driving circuit 118 has been described as outputting both the scan pulse (SP) and the sensing control signal (SCS), it is not limited to this and is controlled by the timing controller 124 to output the sensing control signal (SCS). A separate sensing switch control driver that can output may also be provided.

The data driving circuit 120 can be controlled by a data control signal (DDC) from the timing controller 124, supplies data voltage to the data lines (D1 to Dm) and senses from the sensing lines (S1 to Sk). Voltage can be measured.

Each data line (D1 to Dm) is connected to each pixel 122 to apply a data voltage to each pixel 122.

Each sensing line (S1 to Sk) is connected to the pixel 122 to supply a sensing voltage, and the sensing voltage on the sensing line (S1 to Sk) can be measured. Specifically, by supplying an initialization voltage using one sensing line (S1 to Sk), the sensing voltage using charging and floating can be detected with the initialization voltage.

Although the data driving circuit 120 has been described as being capable of outputting or detecting data voltage and sensing voltage, it is not limited to this and may be provided with a separate driver capable of outputting or detecting sensing voltage.

Each pixel of the organic light emitting display device according to an embodiment of the present invention may include a number of sub-pixels, as shown in FIG. 2 .

Each pixel 122 may refer to one of red, green, blue, and white pixels, and may be separately referred to as a sub-pixel.

The first sub-pixel in FIG. 2 is explained as an example as follows.

Each sub-pixel may include a switching transistor (Tr1), a driving switch (D-Tr), a sensing transistor (Tr2), an organic light emitting diode (EL), and a storage capacitor (Cst1).

The switching transistor (Tr1) is controlled by the scan pulse (SP1) applied to the gate line (G1) and is a transistor for supplying the data voltage (Vdata) applied to the data line (D1) to the sub-pixel 122. It may be connected between the data line D1 and the first node N1.

The driving transistor (D-Tr) is a transistor that controls the current flowing in the organic light emitting diode (EL) by the voltage between the first node (N1) and the second node (N2), which are its gate-source, and is connected to the gate terminal. may be connected to the first node (N1), the source terminal may be connected to the second node (N2), and the drain terminal may be connected to the first driving power source (Vdd).

The sensing transistor (Tr2) is a transistor that controls the second node (N2) to initialize and detect the threshold voltage of the driving transistor (D-Tr) through the sensing line (S1), and is applied to the sensing control line. It can be controlled by the sensing control signal (SCS1).

The storage capacitor Cst1 may be connected between the first and second nodes N1 and N2, that is, between the gate and source terminals of the driving transistor D-Tr.

The anode terminal of the organic light emitting diode (EL) may be connected to the second node (N2), and the cathode terminal may be connected to the second driving power source (Vss).

A sampling transistor (SAM) and a converter (not shown) may be connected to the sensing transistor (Tr2), and an initialization transistor (SPRE) may be connected from a terminal between the sensing transistor (Tr2) and the sampling transistor (SAM).

That is, the initialization switch switches the current flow between the initialization voltage (Vpre) input terminal and the sensing line (S1) in response to the initialization control signal (SPRE). The sampling switch switches the current flow between the sensing line (S1) and the ADC in response to the sampling control signal (SAM) during sensing operation, and drives the driving TFT ( The source voltage of D-Tr) is supplied to the ADC as a sensing voltage.

The ADC converts the analog sensing voltage stored in the sensing capacitor (Cs) into a digital value (Vsen) and supplies it to the timing controller (124). The sampling switch continues to be turned off in response to the sampling control signal (SAM) when driving the image display.

The data compensation method of the organic light emitting diode display device according to the embodiment of the present invention configured as described above will be described as follows.

FIG. 3 is a waveform diagram during a sensing operation of an organic light emitting diode display device according to an embodiment of the present invention, and FIG. 4 is a block diagram for explaining a sensing method of an organic light emitting diode display device according to an embodiment of the present invention.

First, the data compensation method of the organic light emitting diode display according to the embodiment of the present invention, like the conventional external compensation method, changes the amount of change in the electrical characteristics (threshold voltage, mobility) of the driving transistor on a block basis during the turn-off period of the display device. Detect and compensate data in block units.

As described in FIG. 1, m data lines (D1 to Dm), k sensing lines (S1 to Sk), n gate lines (G1 to Gn), and j sensing control lines (SCS1 to SCSj). Among the m Detect and compensate data in block units.

In Figure 2, the subpixel corresponding to one block is shown, but it is divided into a plurality of blocks (1~k, k+1~2k, 2k+1~k3,...) and the electrical characteristics (threshold voltage, Mobility) detects the amount of change and compensates for the data in block units. Here, the condition n ≥ k is satisfied.

That is, as shown in FIG. 3, scan pulses (SP1 to Spk) are applied to all k gate lines (G1 to Gk) of the block, and sensing of the block is performed in response to the initialization control signal (SPRE). Initialize the capacitor (Cs).

Then, in response to the initialization control signal (SPRE), the initialization switch is turned off, and the sensing control signals (SCS1 to SCSk) are simultaneously applied to all k sensing lines of the corresponding block.

Then, all storage capacitors (Cst1 to Cstk) of the block are connected in parallel, so the storage capacitance (Cst) of the block increases (Cst total = Cst1+ Cst2+ Cst3, … +Cstk).

As described above, while all scan pulses (SP1 to Spk) and all sensing control signals (SCS1 to SCSk) remain high, the gate-source voltage (Vgs) of all driving transistors (D-Tr) of the corresponding block ) reaches the saturation state and is charged in the sensing capacitor (Cs).

Then, all of the sensing control signals (SCS1 to SCSk) transition to the low state, the sampling control signal (SAM) goes to the high state, and the source voltage of the driving TFT (D-Tr) stored in the sensing capacitor (Cs) is supplied as the sensing voltage.

In this way, the driving transistor of the corresponding block is simultaneously compensated according to the sensed voltage value.

In this way, the amount of change in the electrical characteristics (threshold voltage, mobility) of the driving transistor is detected for each block, and the data is compensated for on a block-by-block basis, making the unit pixel size very small in an ultra-high-resolution organic light-emitting diode display device. In addition, even if the capacity of the storage capacitor is reduced, the storage capacitance (Cst) of each block increases, so changes in the electrical characteristics (threshold voltage, mobility) of the driving transistor can be detected, and data can be stored on a block-by-block basis. Compensation is possible.

On the other hand, if data is continuously compensated for each block, the device characteristics may be perceived as different for each block.

Therefore, as shown in FIG. 4, block designation can be shifted.

That is, as described above, in the first turn-off section, A block (1st to kth gate lines), B block (k+1th to 2kth gate lines), C block (2k+1th to k3th gates) lines), … If divided, in the second turn-off section, the blocks can be divided by shifting the start and end columns of each block. For example, in the second turn-off section, A' block (2nd to k+1th gate lines), B' block (k+2 to 2k+1th gate lines), C' block (2k+21th to 2nd gate lines), k3+1th gate lines), … If you sense and compensate data by dividing it into blocks, you can prevent the characteristics of each block from becoming fixed.

The block can be configured in various ways (for example, odd-even configuration, multiple configuration, etc.).

Additionally, the number of gate lines in each block may be the same or different.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is commonly known in the technical field to which the present invention pertains that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be clear to those who have the knowledge of.

Claims (6)

In the data compensation method of an organic light emitting diode display device having m to n pixels formed in intersection areas of m data lines, k sensing lines, n gate lines, and j sensing control lines,
dividing a plurality of gate lines among the n gate lines into one block into a plurality of blocks;
A step of sequentially detecting changes in the electrical characteristics of the driving transistors of the block by simultaneously applying scan pulses to all gate lines of the block and simultaneously applying a sensing control signal to all sensing control lines of the block, sequentially block by block. ; and,
Compensating data on a block basis based on the amount of change in electrical characteristics of the detected driving transistors of each block,
A data compensation method for an organic light emitting diode display device, wherein the sensing capacitor of the corresponding block is initialized by an initialization control signal before detecting the amount of change in electrical characteristics of the driving transistors of the corresponding block. According to claim 1,
Before detecting the change in electrical characteristics of the driving transistors of the corresponding block, a scan pulse is simultaneously applied to all gate lines of the corresponding block and initializing the sensing capacitor of the corresponding block by an initialization control signal. Data compensation method. According to claim 1,
Each pixel includes a switching transistor that is controlled by the scan pulse of the corresponding gate line and switches between the corresponding data line and the first node (N1);
The gate terminal is connected to the first node, the source terminal is connected to the second node, and the drain terminal is connected to the first driving power supply to generate a current flowing in the organic light emitting diode by the voltage between the first and second nodes. A driving transistor that controls,
The organic light emitting diode connected between the second node and a second driving power source,
A sensing transistor that is controlled by a sensing control signal applied to the corresponding sensing control line to detect the threshold voltage of the driving transistor,
Provided with a storage capacitor connected between the first and second nodes,
Data compensation of an organic light-emitting diode display device that detects changes in electrical characteristics of the driving transistors of a block by simultaneously applying a scan pulse to all switching transistors of the block and a sensing control signal to all the sensing transistors of the block at the same time method. In clause 3,
an initialization switch that switches the current flow between the initialization voltage input terminal and the corresponding sensing line in response to an initialization control signal;
A data compensation method for an organic light emitting diode display device, further comprising a sampling switch that outputs the source voltage of the driving transistor as a sensing voltage in response to a sampling control signal during sensing driving. According to claim 1,
A scan pulse is applied simultaneously to all gate lines of the block, and a sensing control signal is simultaneously applied to all sensing control lines of the block, and the amount of change in the electrical characteristics of the driving transistors of the block is detected sequentially in block units. A data compensation method for an organic light emitting diode display device in which the step is performed during the turn-off period of the organic light emitting diode display device. According to claim 5,
The step of dividing a plurality of gate lines among the n gate lines into one block includes shifting the gate line designated for the block in the next turn-off period of the organic light-emitting diode display device. Data compensation method.