KR102603600B1 - Electro Luminance Display Device And Compensation Method For Electrical Characteristic Of The Same - Google Patents

Abstract

An electroluminescent display device according to an embodiment of the present invention includes a memory that stores initial offset and gain for each pixel to compensate for initial characteristic differences between pixels; a sensing unit that obtains real-time sensing data for the pixels and stores it in the memory; a parameter calculation unit that modulates the real-time sensing data through a lookup table and calculates an additional offset for each pixel to compensate for changes in the pixels over time based on the modulated sensing data; and a data correction unit that corrects input image data to be written to each pixel based on the initial offset, gain, and additional offset for each pixel.

Description

Electroluminescence display device and method for compensating its electrical characteristics {Electro Luminance Display Device And Compensation Method For Electrical Characteristics Of The Same}

The present invention relates to an electroluminescence display device and a method for compensating its electrical characteristics.

Various display devices are being developed and sold. Among them, electroluminescent display devices are roughly divided into inorganic light emitting display devices and organic light emitting display devices depending on the material of the light emitting layer. In particular, the active matrix type organic light emitting display device includes an organic light emitting diode (hereinafter referred to as “OLED”) that emits light on its own, has a fast response speed, and has excellent luminous efficiency, brightness, and viewing angle. This has a big advantage.

OLED, a self-luminous device, includes an anode electrode and a cathode electrode, and an organic compound layer formed between them. The organic compound layer includes a hole injection layer (HIL), a hole transport layer (HTL), an emissive layer (EML), an electron transport layer (ETL), and an electron injection layer. EIL). When the power supply voltage is applied to the anode electrode and cathode electrode, holes passing through the hole transport layer (HTL) and electrons passing through the electron transport layer (ETL) are moved to the emitting layer (EML) to form excitons, and as a result, the emitting layer (EML) Visible light is generated.

An organic light emitting display device arranges pixels, including an OLED and a driving TFT (Thin Film Transistor), in a matrix form and adjusts the luminance of the input image implemented in the pixels according to the gradation of the image data. The driving TFT controls the driving current flowing to the OLED according to the voltage applied between its gate electrode and source electrode. The amount of light emitted by the OLED is determined by the driving current, and the brightness of the image is determined by the amount of light emitted by the OLED.

The electrical characteristics of the pixel, such as the threshold voltage (Vth) of the driving TFT, the electron mobility (μ) of the driving TFT, and the threshold voltage of the OLED, are the factors that determine the driving current (Ids) and are therefore the same for all pixels. Should be. However, electrical characteristics may vary between pixels due to various reasons such as process characteristics and time-varying characteristics. This variation in electrical characteristics causes luminance variation, which limits the ability to create a desired image.

In order to compensate for luminance differences between pixels, an external compensation technology is known that senses the electrical characteristics of pixels and corrects digital data of an input image based on the sensing results. In order for the luminance deviation to be compensated, a current change equal to Δy must be guaranteed when the data voltage applied to the pixel changes by Δx. Therefore, external compensation technology calculates Δx for each pixel and applies the same driving current to the OLED to achieve the same brightness. In other words, external compensation technology adjusts the grayscale value to compensate for the brightness of each pixel to be the same.

This external compensation technology obtains one average panel current (I)-voltage (V) curve through multiple sensings and may include a compensation algorithm that compensates so that the I-V curve of each pixel matches the average panel I-V curve. In order to obtain the I-V curve of each pixel, digital sensing data for at least N gray levels (N is a positive integer of 3 or more) is required. Sensing data of N gray levels is obtained through a sensing time corresponding to N frames, and as N increases, the sensing time increases. Because this external compensation technology takes a lot of time to accumulate sensing data of N gray levels for each pixel, there are limitations in compensating for changes in the electrical characteristics of the pixel in real time.

In addition, external compensation technology requires storing N grayscale sensing data for each pixel before executing the compensation algorithm, so a large storage memory is required. As the resolution of the display panel increases, the capacity of the storage memory must increase, causing problems in terms of circuit size and manufacturing cost.

Therefore, the purpose of the present invention is to provide an electroluminescence display device and a method for compensating its electrical characteristics that can reduce sensing data and sensing time.

In order to achieve the above object, an electroluminescent display device according to an embodiment of the present invention includes a memory that stores initial offset and gain for each pixel to compensate for initial characteristic deviation between pixels; a sensing unit that obtains real-time sensing data for the pixels and stores it in the memory; a parameter calculation unit that modulates the real-time sensing data through a lookup table and calculates an additional offset for each pixel to compensate for changes in the pixels over time based on the modulated sensing data; and a data correction unit that corrects input image data to be written to each pixel based on the initial offset, gain, and additional offset for each pixel.

The real-time sensing data is sensing data for one gray level.

The parameter calculation unit derives an average current-voltage equation of the display panel by applying the least square method to the initial sensing results of multiple gray levels for the pixels, and calculates the average current-voltage equation. Store more in the memory.

The parameter calculation unit calculates the initial offset and gain for each pixel so that the current characteristics for each pixel based on the initial sensing result for each pixel are equal to the average current characteristic based on the average current-voltage formula of the display panel and stores the initial offset and gain in the memory. Save.

The parameter calculation unit calculates the parameters necessary for the current-voltage formula for each pixel based on the initial sensing values measured at two gray level points, and calculates the parameters necessary for the current-voltage formula for each pixel to match the average current-voltage formula. The initial offset and gain are calculated for each pixel.

The parameter calculation unit calculates an additional offset for each pixel to compensate for changes in the pixels over time by substituting the modulated sensing data into the following equation,

In the above formula, Ki represents the additional offset for each pixel, cap represents the line capacitance of the sensing line connected to the pixel, at, bt and c represent parameters included in the average current-voltage formula, and ∇t is Represents the sensing time required to obtain real-time sensing data of one gray level, ADCi represents real-time sensing data of one gray level, (ADCi) ^1/c represents the modulated sensing data, and Gi represents each pixel. It represents the star gain, Oi represents the initial offset for each pixel, and Vdata represents the data voltage corresponding to the real-time sensing data of the one gray level.

The lookup table outputs the modulated sensing data using the real-time sensing data as a read address.

In addition, a method for compensating electrical characteristics of an electroluminescent display device according to an embodiment of the present invention includes the steps of storing the initial offset and gain for each pixel in a memory to compensate for the initial characteristic deviation between pixels; Obtaining real-time sensing data for the pixels and storing them in the memory; Modulating the real-time sensing data through a lookup table and calculating an additional offset for each pixel to compensate for changes in the pixels over time based on the modulated sensing data; and correcting input image data to be written to each pixel based on the initial offset, gain, and additional offset for each pixel.

The present invention obtains only one gray level of real-time sensing data for each pixel when driving real-time sensing that senses changes in pixels over time, and calculates only one parameter among offset and gain that has a relatively greater impact on image quality, so that the sensing data and Sensing time can be dramatically reduced.

In addition, since the present invention obtains only one gray level of real-time sensing data for each pixel when driving real-time sensing to sense changes in pixels over time, the capacity of the storage memory that stores real-time sensing data can be greatly reduced.

In addition, the present invention uses a lookup table instead of a calculation algorithm when calculating an additional offset to compensate for changes in pixels over time, thereby significantly reducing the amount of calculation and calculation time.

1 is a block diagram showing an electroluminescent display device according to an embodiment of the present invention.
Figure 2 is a block diagram showing an external compensation circuit according to an embodiment of the present invention.
Figure 3 is a flowchart showing an external compensation method according to an embodiment of the present invention.
FIG. 4A is a diagram illustrating deriving the average IV formula of the display panel using the external compensation method of FIG. 3.
FIG. 4B is a diagram showing the average IV curve of the display panel and the IV curve of the pixel to be compensated in the external compensation method of FIG. 3.
FIG. 4C is a diagram showing the average IV curve of the display panel, the IV curve of the pixel to be compensated, and the IV curve of the pixel for which initial compensation has been completed in the external compensation method of FIG. 3.
FIGS. 5A and 5B are diagrams showing a real-time external compensation technique for fitting the IV curve of a pixel according to a change over time with the IV curve of an initially compensated pixel in the external compensation method of FIG. 3.
Figure 6 is a graph showing the relationship between ADC sensing range and additional offset.
Figure 7 is a lookup table in which modulated sensing data output using the ADC output value as a read address is stored.
8 to 10 are diagrams showing various implementation examples of an external compensation module.

The advantages and features of the present invention and methods for achieving them will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms, but the present embodiments only serve to ensure that the disclosure of the present invention is complete and are within the scope of common knowledge in the technical field to which the present invention pertains. It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

The shapes, sizes, proportions, angles, numbers, etc. disclosed in the drawings for explaining embodiments of the present invention are illustrative, and the present invention is not limited to the matters shown. Like reference numerals refer to like elements throughout the specification. Additionally, in describing the present invention, if it is determined that a detailed description of related known technologies may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. When 'includes', 'has', 'consists of', etc. mentioned in the specification are used, other parts may be added unless '~ only' is used. When a component is expressed in the singular, the plural is included unless specifically stated otherwise.

When interpreting a component, it is interpreted to include the margin of error even if there is no separate explicit description.

In the case of a description of a positional relationship, for example, if the positional relationship between two parts is described as 'on top', 'on top', 'at the bottom', 'next to ~', 'right next to' Alternatively, there may be one or more other parts placed between the two parts, unless 'directly' is used.

Although first, second, etc. are used to describe various elements, these elements are not limited by these terms. These terms are merely used to distinguish one component from another. Accordingly, the first component mentioned below may also be the second component within the technical spirit of the present invention.

Like reference numerals refer to like elements throughout the specification.

Each of the features of the various embodiments of the present invention can be combined or combined with each other partially or entirely, and various technical interconnections and operations are possible, and each embodiment may be implemented independently of each other or together in a related relationship. It may be possible.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the attached drawings. In the following embodiments, the description will focus on an organic light emitting display device including an organic light emitting material. However, it should be noted that the technical idea of the present invention is not limited to organic light emitting display devices, but can be applied to inorganic light emitting display devices including inorganic light emitting materials.

1 and 2, the electroluminescent display device according to an embodiment of the present invention includes a display panel 10, a driver IC (D-IC) 20, a compensation IC 30, and a host system 40. , and may include a storage memory 50.

The display panel 10 is provided with a plurality of pixels (PXL) and a plurality of signal lines. The signal lines include a plurality of data lines that supply an analog data voltage to the pixel (PXL), a plurality of gate lines that supply a gate signal to the pixel (PXL), and a plurality of sensing lines used to sense the electrical characteristics of the pixel (PXL). may include. Depending on the pixel (PXL) structure, the sensing line may be replaced with a data line. In this case, the data line is used to supply an analog data voltage and is also used to sense the electrical characteristics of the pixel (PXL). The analog data voltage includes the data voltage for display (Vdata-DIS) and the data voltage for sensing (Vdata-SEN). The electrical characteristics of the pixel (PXL) include the threshold voltage of the driving TFT, the electron mobility of the driving TFT, and the operating point voltage of the OLED.

The pixels (PXL) of the display panel 10 are arranged in a matrix form to form a pixel array. Each pixel (PXL) may be connected to one of the data lines, at least one of the gate lines, and one of the sensing lines. Each pixel (PXL) is configured to receive high-potential driving power (VDD) and low-potential driving power (VSS) from the power generator. To this end, the power generation unit can supply high-potential driving power to the pixel (PXL) through the high-potential pixel power wiring or pad unit. Additionally, the power generation unit may supply low-potential driving power to the pixel (PXL) through the low-potential pixel power wiring or pad unit.

The gate driver 15 may separately generate a gate signal required for display driving and a gate signal required for sensing driving.

The gate driver 15 may generate a gate signal for the display when driving the display and supply it to the gate line. The display gate signal is a signal that is synchronized with the writing timing of the display data voltage (Vdata-DIS).

The gate driver 15 may generate a sensing gate signal and supply it to the gate line during sensing operation. The gate signal for sensing is a signal that is synchronized with the writing timing and sensing timing of the sensing data voltage (Vdata-SEN).

The gate driver 15 may be formed directly on the lower substrate of the display panel 10 using a gate-driver in panel (GIP) method. The gate driver 15 is formed in a non-display area (i.e., bezel area) outside the pixel array of the display panel 10, and may be formed using the same TFT process as the pixel array. Meanwhile, the gate driver 15 may be manufactured as an integrated circuit (IC) and bonded to one side of the display panel 10.

The driver IC (D-IC) 20 is connected to the data line and sensing line of the display panel 10. The driver IC (D-IC) 20 may include a timing control unit 21 and a data driver 25.

The timing control unit 21 refers to timing signals input from the host system 40, such as the vertical synchronization signal (Vsync), horizontal synchronization signal (Hsync), dot clock signal (DCLK), and data enable signal (DE). A gate timing control signal (GDC) for controlling the operation timing of the gate driver 15 and a data timing control signal (DDC) for controlling the operation timing of the data driver 25 can be generated.

The data timing control signal (DDC) may include, but is not limited to, a source start pulse, a source sampling clock, and a source output enable signal. The source start pulse controls the data sampling start timing of the data driver 25. The source sampling clock is a clock signal that controls the sampling timing of data based on the rising or falling edge. The source output enable signal controls the output timing of the data driver 25.

The gate timing control signal (GDC) may include, but is not limited to, a gate start pulse and a gate shift clock. The gate start pulse is applied to the stage that produces the first output and activates the operation of that stage. The gate shift clock is a clock signal commonly input to the stages and is a clock signal for shifting the gate start pulse.

The timing control unit 21 can control the sensing mode for sensing driving and the display mode for display driving according to a predetermined control sequence. The timing control unit 21 may generate timing control signals for display driving and timing control signals for sensing driving differently. However, it is not limited to this.

In sensing mode, preset grayscale data is converted into a data voltage for sensing and applied to the pixels (PXL), and the electrical characteristics of the pixels (PXL) are sensed to obtain digital sensing data (S-DATA) and digital sensing data ( The input image data to be written to the pixels (PXL) is corrected based on (S-DATA). And, in the display mode, the corrected image data is converted into a display data voltage (Vdata-DIS) and applied to the pixels (PXL).

The sensing drive includes an initial sensing drive to sense characteristic deviations between pixels (PXL) according to the manufacturing process and a real-time sensing drive to sense characteristic deviations between pixels (PXL) due to changes over time. The initial sensing drive may be performed in an initial state before changes over time occur under the control of the timing control unit 21.

On the other hand, real-time sensing driving is performed under the control of the timing control unit 21 in the vertical blank period during display driving, or in the power-on sequence period before display driving begins, or in the power-off sequence after display driving ends. It can be performed in a sequence period. However, it is not limited to this, and sensing driving can also be performed during the vertical active period during display driving.

Here, the vertical blank period is a period in which input image data is not written, and is disposed between vertical active sections in which one frame of input image data is written. The power-on sequence period refers to the transient period from when the driving power is turned on until the input image is displayed. The power-off sequence period refers to the transient period from when the display of the input image ends until the driving power is turned off.

Additionally, the timing control unit 21 can control overall operations for real-time sensing driving according to a predetermined sensing process. That is, real-time sensing operation may be performed in a state where only the screen of the display device is turned off while the system power is being applied, for example, in standby mode, sleep mode, or low power mode.

The data driver 25 includes a sensing unit 22 and a data voltage generator 23.

The data voltage generator 23 may include a digital to analog converter (DAC) that converts a digital signal into an analog signal and an output buffer (not shown). The DAC generates a data voltage for display (Vdata-DIS) or a data voltage for sensing (Vdata-SEN). The output buffer stabilizes the data voltage (Vdata-DIS, Vdata-SEN) input from the DAC and then outputs it.

When driving the display, the data voltage generator 23 converts the corrected image data (V-DATA) into an analog gamma voltage using a DAC, and transmits the conversion result to the data lines as a data voltage for display (Vdata-DIS). supply. When driving a display, the display data voltage (Vdata-DIS) supplied to the data lines is applied to the pixels (PXL) in synchronization with the turn-on timing of the display gate signal. The voltage between the gate and source of the driving TFT provided in the pixels (PXL) is programmed by the display data voltage (Vdata-DIS), and the driving current flowing through the driving TFT is determined according to the voltage between the gate and source of the driving TFT.

During the initial sensing operation, the data voltage generator 23 generates a data voltage (Vdata-SEN1) for sensing of multiple gray levels using a DAC and then supplies it to the data lines. During the initial sensing operation, the multi-gray sensing data voltage (Vdata-SEN1) supplied to the data lines is applied to the pixels (PXL) in synchronization with the turn-on timing of the sensing gate signal. The voltage between the gate and source of the driving TFT provided in the pixels (PXL) is programmed by the data voltage for sensing (Vdata-SEN1) of multiple gray levels, and the current flowing through the driving TFT is determined according to the voltage between the gate and source of the driving TFT. And this current becomes the target of sensing.

When driving real-time sensing, the data voltage generator 23 generates a data voltage (Vdata-SEN2) for sensing of one gray level using a DAC and then supplies it to the data lines. During real-time sensing operation, the sensing data voltage (Vdata-SEN2) of one gray level supplied to the data lines is applied to the pixels (PXL) in synchronization with the turn-on timing of the sensing gate signal. The voltage between the gate and source of the driving TFT provided in the pixels (PXL) is programmed by the data voltage for sensing (Vdata-SEN2) of one gray level, and the current flowing through the driving TFT is programmed according to the voltage between the gate and source of the driving TFT. is determined, and this current becomes the target of sensing.

During the initial sensing operation, the sensing unit 22 can measure the initial electrical characteristics of the pixel (PXL) by sensing the current flowing in the pixel (PXL) according to the multi-gradation sensing data voltage (Vdata-SEN1). When driving real-time sensing, the sensing unit 22 senses the current flowing in the pixel (PXL) according to the sensing data voltage (Vdata-SEN2) of one gray level and measures the electrical characteristics according to changes in the pixel (PXL) over time. You can. This sensing unit 22 may include a sensing unit and an analog-to-digital converter (hereinafter referred to as an ADC).

The sensing unit may be implemented as a voltage sensing type including a sample and hold unit, or a current sensing type including a current integrator and a sample and hold unit. The sensing unit samples the current flowing through the driving TFT during initial sensing operation and real-time sensing operation, and supplies the sampled result to the ADC.

During the initial sensing operation, the ADC converts the analog sampling signal input from the sensing unit into a digital signal and generates first digital sensing data (S-DATA1) representing the initial electrical characteristics of the pixel (PXL). Additionally, the ADC converts the analog sampling signal input from the sensing unit into a digital signal during real-time sensing operation and generates second digital sensing data (S-DATA2) that represents electrical characteristics according to changes in the pixel (PXL) over time. The ADC supplies first digital sensing data (S-DATA1) according to the initial sensing result and second digital sensing data (S-DATA2) according to the real-time sensing result to the storage memory 50. This ADC can be implemented as a flash type ADC, an ADC using a tracking technique, or a successive approximation register type ADC.

The compensation IC 30 derives the average current (I) - voltage (V) formula of the display panel based on the first digital sensing data (S-DATA1) read from the storage memory 50 during the initial sensing operation, Save it in the storage memory (50).

The compensation IC 30 calculates the pixels ( The initial offset (OFS1) and gain (GA) for each pixel to compensate for the initial characteristic deviation between PXL) are calculated and stored in the storage memory 50.

When driving real-time sensing, the compensation IC 30 modulates the second digital sensing data (S-DATA2) read from the storage memory 50 through the lookup table 34, and pixels (PXL) based on the modulated sensing data. ) Calculate an additional offset (OFS2) for each pixel to compensate for changes over time. In addition, the compensation IC 30 provides an input to be written to each pixel (PXL) based on the calculated additional offset (OFS2) and the initial offset (OFS1) and gain (GA) for each pixel read from the storage memory 50. Correct the video data.

This compensation IC 30 may include a parameter calculation unit 31, a compensation memory 32, a data correction unit 33, and a look-up table 34.

The parameter calculation unit 31 calculates one average for all pixels of the panel based on the first digital sensing data (S-DATA1) of N (N is a positive integer of 2 or more) gray levels obtained through multiple sensing during the initial sensing operation. A compensation algorithm may be included to obtain a current (I)-voltage (V) curve and compensate so that the I-V curve of each pixel matches the average panel I-V curve.

Specifically, during the initial sensing operation, the parameter calculation unit 31 uses the known least square method on the initial sensing results for multiple gray levels (e.g., a total of 7 gray levels including A to F) as shown in FIGS. 3 and 4A. method] is applied to derive the following equation 1 corresponding to the average I-V curve and store it in the storage memory 50 (S1).

In Equation 1, “a” is the electron mobility of the driving TFT, “b” is the threshold voltage of the driving TFT, and “c” represents the physical characteristic value of the driving TFT. While “a” and “b” are values that vary depending on changes over time, “c” is a value that is independent of changes over time.

During the initial sensing operation, the parameter calculation unit 31 calculates the initial current values (I1, I2) of the two grayscale points included in the first digital sensing data (S-DATA1) and the corresponding grayscale value (X) as shown in FIGS. 3 and 4B. ,Y grayscale) (i.e., data voltage values (Vdata1, Vdata2)), the a' value and b' value, which are parameter values required for the I-V equation of each pixel (PXL), are calculated (S2).

The parameter calculation unit 31 may calculate the a' value and the b' value, which are parameter values of the corresponding pixel (PXL), using the quadratic equation in Equation 2 above.

During the initial sensing operation, the parameter calculation unit 31 calculates the initial offset (OFS1) and gain (GA) for each pixel to ensure that the I-V curve of each pixel (PXL) matches the average I-V curve as shown in FIGS. 3 and 4C ( S3). The initial offset (OFS1) and gain (GA) are as shown in Equation 3 below. In Equation 3, “Vcomp” indicates a digital level compensation voltage, and Vdata indicates a digital level data voltage corresponding to input image data.

The parameter calculation unit 31 uses only the second digital sensing data (S-DATA2) of one gray level when driving real-time sensing, and calculates only one parameter among offset and gain that has a relatively greater impact on image quality, thereby Significantly reduces sensing time. Specifically, the sensing unit 22 acquires second digital sensing data (S-DATA2) of one gray level during real-time sensing operation and stores it in the storage memory 50. At this time, the parameter calculation unit 31 reads the second digital sensing data (S-DATA2) of one gray level from the storage memory 50 (S4). Then, the parameter calculation unit 31 reads the modulated sensing data from the lookup table 34 using the second digital sensing data (S-DATA2) as a read address (S5). Then, the parameter calculation unit 31 substitutes the modulated sensing data into Equation 4 below to calculate an additional offset OFS2 for each pixel to compensate for changes in the pixels PXL over time (S6).

In Equation 4, all remaining factors other than (ADCi) ^1/c are pre-calculated and known values. Ki represents the additional offset (OFS2) for each pixel, cap represents the line capacitance of the sensing line connected to the pixel (PXL), at, bt and c represent parameters included in the average IV formula of the display panel, and ∇t represents the sensing time required to obtain the second digital sensing data (S-DATA2), which is real-time sensing data of one gray level, and ADCi represents the second digital sensing data (S-DATA2), which is real-time sensing data of one gray level. , (ADCi) ^1/c represents the sensing data modulated through the lookup table 34, Gi represents the gain (GA) for each pixel, Oi represents the initial offset (OFS1) for each pixel, and Vdata is 1. Indicates the data voltage corresponding to real-time sensing data of 0 gray levels.

The electrical characteristic curve of the pixel (PXL) may change from the initial state Ii to Ii' according to changes over time, as shown in FIG. 5A. For example, the threshold voltage (Vth) of the driving TFT included in the pixel (PXL) may increase with change over time. The additional offset (OFS2) of the pixel is to compensate for this change over time. If the additional offset (OFS2) is further reflected in correcting the input image data, the electrical characteristic curve of the pixel (PXL) can be fitted to the initial state as shown in FIG. 5B.

In Figure 6, the relationship between the ADC sensing range and the additional offset (OFS2,K) is shown graphically. For example, if the sensing range of the ADC actually used is 20 to 200, modulated sensing data may be preset in the lookup table 34 to correspond to the sensing range of 20 to 200, as shown in FIG. 7.

In Equation 4, (ADCi) ^1/c , which is the modulated sensing data, is obtained through the lookup table 34 without a separate operation. (ADCi) When calculating ^1/c in real time, the amount of calculation is very large and requires a lot of calculation time. By using the lookup table 34 as in the present invention, the modulation value of the second digital sensing data (S-DATA2), which is real-time sensing data (ADCi), can be found more quickly without separate calculation.

In the compensation memory 32, the additional offset (OFS2) of each pixel (PXL) calculated by the parameter calculation unit 31 is downloaded, and each pixel (PXL) previously stored in the storage memory 50 is downloaded. The initial offset (OFS1) and gain (GA) are downloaded. The compensation memory 32 may be RAM (Random Access Memory), for example, DDR SDRAM (Double Date Rate Synchronous Dynamic RAM), but is not limited thereto.

The data correction unit 33 calculates the digital value to be input to the corresponding pixel (PXL) based on the initial offset (OFS1), gain (GA), and additional offset (OFS2) of each pixel (PXL) read from the compensation memory 32. Correct the image data (S7). For this purpose, the data correction unit 33 may include a multiplier 33A and an adder 33B. The multiplier 33A multiplies the input digital image data by the gain (GA) and supplies it to the adder 33B. The adder 33B adds the initial offset (OFS1) and the additional offset (OFS2) to the output result of the multiplier 33A and outputs the result as corrected digital image data (V-DATA).

The host system 40 may supply digital image data to be input to the pixels (PXL) of the display panel 10 to the compensation IC 30. The host system 40 may further supply user input information such as digital brightness information to the compensation IC 30. The host system 40 may be implemented as an application processor.

The storage memory 50 includes first digital sensing data of multiple gray levels (S-DATA1), second digital sensing data of one gray level (S-DATA2), initial offset (OFS1) and gain (GA) for each pixel, and display Save the average I-V formula of the panel, etc. The storage memory 50 may be implemented as a flash memory, but is not limited thereto.

8 to 10 are diagrams showing various implementation examples of an external compensation module.

Referring to FIG. 8, the electroluminescent display device of the present invention includes a driver IC (D-IC) 20 mounted on a chip on film (COF) and a flexible printed circuit board to implement an external compensation module. Equipped with a storage memory 50 and a power IC (P-IC) 60 mounted on a flexible printed circuit board (FPCB), and a host system 40 mounted on a system printed circuit board (SPCB). can do.

The driver IC (D-IC) 20 may further include a compensation unit 36 and a compensation memory 32 in addition to the timing control unit 21, the sensing unit 22, and the data voltage generator 23. The compensation unit 36 includes the parameter calculation unit 31 and data correction unit 33 of FIGS. 1 and 2.

This external compensation module is a single chip comprising a driver IC (D-IC) 20 and a compensation IC ('30' in Figure 1). The power IC (P-IC) 60 generates various driving powers required to operate this external compensation module.

Additionally, referring to FIG. 9, the electroluminescent display device of the present invention includes a driver IC (D-IC) 20 mounted on a chip-on-film (COF) and a flexible printed circuit board (FPCB) to implement an external compensation module. ) may be provided with a storage memory 50 and a power IC (P-IC) 60 mounted on the host system 40 mounted on a system printed board (SPCB).

The external compensation module of FIG. 9 is different from FIG. 8 in that the compensation unit 36 and compensation memory 32 are mounted on the host system 40 rather than on the driver IC (D-IC) 20. The external compensation module of FIG. 9 is meaningful in that the compensation IC ('30' in FIG. 1) is integrated into the host system 40, and the configuration of the driver IC (D-IC) 20 can be simplified. there is.

In addition, referring to FIG. 10, the electroluminescent display device of the present invention includes a driver IC (D-IC) 20 mounted on a chip-on-film (COF) and a flexible printed circuit board (FPCB) to implement an external compensation module. ), a storage memory 50, a compensation IC 30, a compensation memory 32, and a power IC (P-IC) 60, and a host system 40 mounted on a system printed circuit board (SPCB). can do.

The external compensation module of FIG. 10 further simplifies the configuration of the driver IC 20 by mounting only the data voltage generator 23 and the sensing unit 22 on the driver IC 20, and includes the timing control unit 21 and the compensation unit. (36) is different in that it is mounted on a separately manufactured compensation IC (30). Additionally, there is an advantage in that data uploading and downloading operations can be facilitated by mounting the compensation IC 30, the storage memory 50, and the compensation memory 32 together on a flexible printed circuit board (FPCB).

As described above, the present invention obtains only one gray level of real-time sensing data for each pixel when driving real-time sensing to sense changes in pixels over time, and calculates only one parameter among offset and gain that has a relatively greater impact on image quality. By doing so, sensing data and sensing time can be dramatically reduced.

In addition, since the present invention obtains only one gray level of real-time sensing data for each pixel when driving real-time sensing to sense changes in pixels over time, the capacity of the storage memory that stores real-time sensing data can be greatly reduced.

In addition, the present invention uses a lookup table instead of a calculation algorithm when calculating an additional offset to compensate for changes in pixels over time, thereby significantly reducing the amount of calculation and calculation time.

Through the above-described content, those skilled in the art will be able to see that various changes and modifications can be made without departing from the technical idea of the present invention. Therefore, the technical scope of the present invention should not be limited to what is described in the detailed description of the specification, but should be defined by the scope of the patent claims.

10: display panel 20: driver IC
15: gate driver 21: timing control unit
22: sensing unit 23: data voltage generating unit
30: Compensation IC 31: Parameter calculation unit
33: data correction unit 34: lookup table
40: host system 50: storage memory

Claims (14)

A memory that stores the initial offset and gain for each pixel calculated in advance to compensate for initial characteristic deviations between pixels through initial sensing prior to real-time sensing;
a sensing unit that obtains real-time sensing data of one gray level for the pixels through the real-time sensing and stores it in the memory;
Modulating the real-time sensing data of the one gray level read from the memory to fall within the sensing range of the analog-digital converter through a lookup table, and compensating for changes in the pixels over time based on the modulated sensing data of the one gray level. a parameter calculation unit that calculates only the additional offset for each pixel; and
An electroluminescent display device comprising a data correction unit that corrects input image data to be written to each pixel based on the initial offset and the gain read from the memory, and the additional offset input from the parameter calculation unit. delete According to claim 1,
The parameter calculation unit,
The average current-voltage formula of the display panel is derived in advance by applying the least square method to the initial sensing results of multiple gray levels for the pixels obtained through the initial sensing, and the average current -An electroluminescent display device that further stores a voltage formula in the memory. According to claim 3,
The parameter calculation unit,
Electroluminescence in which the initial offset and gain for each pixel are calculated in advance and stored in the memory so that the current characteristics of each pixel based on the initial sensing result for each pixel are equal to the average current characteristics based on the average current-voltage formula of the display panel. Display device. According to claim 4,
The parameter calculation unit,
The parameters required for the current-voltage formula for each pixel are calculated in advance based on the initial sensing values for the two grayscale points obtained through the initial sensing, and the current-voltage formula for each pixel is the average current-voltage formula. An electroluminescent display device that pre-calculates the initial offset and gain for each pixel to match . According to claim 1,
The parameter calculation unit,
Substituting the modulated sensing data of one gray level into the following equation to calculate an additional offset for each pixel to compensate for changes in the pixels over time,

In the above formula, Ki represents the additional offset for each pixel, cap represents the line capacitance of the sensing line connected to the pixel, and at, bt, and c are the average current-voltage formula of the display panel obtained through the initial sensing. represents the parameter, ∇t represents the sensing time required to obtain the real-time sensing data of the one gray level, ADCi represents the real-time sensing data of the one gray level, and (ADCi) ^1/c represents the modulated sensing data. wherein Gi represents the gain for each pixel, Oi represents the initial offset for each pixel, and Vdata represents the data voltage corresponding to the real-time sensing data of the one gray level. According to claim 1,
The lookup table is an electroluminescent display device that uses the real-time sensing data of the one gray level as a read address and outputs the modulated sensing data of the one gray level. Through initial sensing prior to real-time sensing, storing the pre-calculated initial offset and gain for each pixel in a memory to compensate for initial characteristic deviations between pixels;
acquiring real-time sensing data of one gray level for the pixels through the real-time sensing and storing it in the memory;
Modulating the real-time sensing data of the one gray level read from the memory to fall within the sensing range of the analog-digital converter through a lookup table, and compensating for changes in the pixels over time based on the modulated sensing data of the one gray level. calculating only an additional offset for each pixel; and
A method of compensating electrical characteristics of an electroluminescent display device, comprising correcting input image data to be written to each pixel based on the initial offset and the gain read from the memory, and the additional offset input from the parameter calculation unit. delete According to claim 8,
The average current-voltage formula of the display panel is derived in advance by applying the least square method to the initial sensing results of multiple gray levels for the pixels obtained through the initial sensing, and the average current - A method of compensating electrical characteristics of an electroluminescent display device further comprising the step of storing a voltage formula in the memory. According to claim 10,
Calculating the initial offset and gain for each pixel in advance and storing them in the memory so that the current characteristics for each pixel based on the initial sensing result for each pixel are equal to the average current characteristics based on the average current-voltage formula of the display panel. A method for compensating electrical characteristics of an electroluminescent display device further comprising: According to claim 11,
The step of calculating the initial offset and gain for each pixel is,
The parameters required for the current-voltage formula for each pixel are calculated in advance based on the initial sensing values for the two grayscale points obtained through the initial sensing, and the current-voltage formula for each pixel is the average current-voltage formula. A method of compensating the electrical characteristics of an electroluminescent display device, which is a step of pre-calculating the initial offset and gain for each pixel to match the . According to claim 8,
The step of calculating the additional offset for each pixel is,
Calculate an additional offset for each pixel by substituting the modulated sensing data of one gray level into the following equation,

In the above formula, Ki represents the additional offset for each pixel, cap represents the line capacitance of the sensing line connected to the pixel, and at, bt, and c are the average current-voltage formula of the display panel obtained through the initial sensing. represents the parameter, ∇t represents the sensing time required to obtain the real-time sensing data of the one gray level, ADCi represents the real-time sensing data of the one gray level, and (ADCi) ^1/c represents the modulated sensing data. wherein Gi represents the gain for each pixel, Oi represents the initial offset for each pixel, and Vdata represents the data voltage corresponding to the real-time sensing data of the one gray level. A method of compensating electrical characteristics of an electroluminescent display device. According to claim 8,
The look-up table is a method of compensating electrical characteristics of an electroluminescent display device in which the real-time sensing data of the one gray level is used as a read address and the modulated sensing data of the one gray level is output.