KR100883901B1 - Crosstalk compensation circuit of passive matrix OLED - Google Patents

Abstract

The present invention controls the precharge current when each scan line is driven by using the average of image data input for each scan line of the passive matrix OLED panel, thereby reducing the difference in voltage generated in each scan line and reducing the difference between the OLEDs at each scan line. A crosstalk compensator for a passive matrix OLED that reduces crosstalk significantly by reducing a difference in voltage generated, comprising: a scan driver; An image data unit for outputting image data; An average calculator for calculating an average of the output image data to calculate an average of the image data to be applied to the scan line; A precharge current controller using this average; A bias controller configured to set a current level of the data line; A data driver configured to output OLED panel driving data by modulating the image data into a PAM driving waveform; A driver controller which controls the data driver according to the current level of the data line and the current level of the precharge; And a passive matrix OLED panel driven by the scan signal and the driving data output from the scan driver.

PM, PAM, OLED, Crosstalk, Scan Driver, Average Calculator, Bias Control, Precharge Current

Description

Crosstalk compensation circuit of passive matrix OLED

1 is a diagram briefly illustrating a configuration of a crosstalk compensator of a passive matrix OLED according to an embodiment of the present invention.

 FIG. 2 is a diagram illustrating the precharge current controller shown in FIG. 1 in detail.

3 is a diagram representing a formula for obtaining correction data using an average value output from the average calculator shown in FIG. 2.

4 is a diagram illustrating a voltage / current level of an A / B / C region and a current applied to an OLED in the precharge voltage controller according to an embodiment.

FIG. 5 is a diagram illustrating a result of image correction according to the current characteristics shown in FIG. 4.

FIG. 6 is a diagram illustrating a voltage / current level in an A / B / C region and a current applied to an OLED in a precharge current controller according to another embodiment.

FIG. 7 is a diagram illustrating a result of image correction according to the current characteristics shown in FIG. 6.

8 is a diagram illustrating a crosstalk image according to the prior art.

 <Explanation of symbols for the main parts of the drawings>

110: scan driver

120: image data portion

130: average calculator

140: precharge current control unit

150: bias control unit

160: data driver

170: driver control unit

180: Passive Matrix OLED Panel

The present invention relates to a crosstalk compensation device of a passive matrix OLED, and in particular, by controlling the precharge current when each scan line is driven by using an average of image data input for each scan line of the passive matrix OLED panel. The present invention relates to a crosstalk compensation device of a passive matrix OLED which significantly reduces crosstalk by reducing a difference in voltage generated in each scan line and a difference in voltage generated across OLEDs by scan line.

In general, the driving IC for driving a passive matrix (PM) OLED (organic EL) panel, which is applied to a portable device, is classified into a pulse width modulation (PWM) and a pulse size modulation method depending on the method. It is divided into (PAM: Pulse Amplitude Modulation).

Since the passive matrix OLED is a current driving method, a voltage drop due to a current occurs in the metal resistance component of the scan line when the screen is driven. That is, the brightness of each scan line is changed due to the scan line voltage drop caused by the parasitic resistance component of the scan line, and the change or brightness interference of the screen is referred to as crosstalk.

The luminance of each pixel has a property that is almost proportional to the amount of current flowing in the OLED pixel, and the voltage generated in the scan line is changed by the image data input for each scan line.

Accordingly, there is a problem in that crosstalk occurs because image data having the same luminance has different luminance according to scan lines.

That is, as shown in FIG. 8, the scan line of the image B region of the crosstalk generates a lower voltage than the region A, thereby lowering the potential of the data line. There is a problem that crosstalk appears.

In order to solve the above problems, the present invention controls the precharge current when each scan line is driven by using an average of image data input for each scan line of the passive matrix OLED panel, and thus the difference in voltage generated in each scan line. It is an object of the present invention to provide a crosstalk compensation device for a passive matrix OLED which reduces crosstalk and significantly reduces crosstalk by reducing the difference in voltage generated across the OLED lines by scan lines.

In order to achieve the above objects, a crosstalk compensation device of a passive matrix OLED according to an aspect of the present invention, the scan driver for outputting a scan signal; An image data unit for outputting image data; An average calculator for calculating an average of the output image data to calculate an average of the image data to be applied to the scan line; A precharge current controller for controlling the current level of the precharge using the average output from the average calculator; A bias control unit for setting a current level of the data line; A data driver configured to output driving data for driving the OLED panel by modulating the image data output from the image data unit into a PAM driving waveform; A driver controller controlling the data driver to output the driving data through a data driver according to a current level of a data line set by the bias controller and a current level of a precharge controlled by the precharge current controller; And a passive matrix OLED panel driven by a scan signal output from the scan driver and driving data output from the data driver.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Hereinafter, a configuration of a crosstalk compensator of a passive matrix OLED according to an embodiment of the present invention will be described with reference to FIGS. 1 to 7. FIG. 1 illustrates a cross of a passive matrix OLED according to an embodiment of the present invention. 2 is a diagram schematically illustrating a configuration of a torque compensator, and FIG. 2 is a diagram illustrating in detail the precharge current control unit shown in FIG. 1, and FIG. 3 is an equation for obtaining correction data using an average value output from the average calculator shown in FIG. 2. This is a diagram representing.

Crosstalk compensation device of the passive matrix OLED according to an embodiment of the present invention, the scan driver 110, the image data unit 120, the average calculator 130, the precharge current control unit 140, the bias control unit 150 , A data driver 160, a driver controller 170, and a passive matrix OLED panel 180.

The scan drive 110 outputs a scan signal, and the data driver 160 outputs a current source of each PAM0 to PAM (m-1), a precharge changeover switch of PRC0 to PRC (m-1), and a RESET0 to RESET. It consists of a reset switch of (m-1), and each data line of this data driver 160 generates a PAM drive waveform from 0 to 63 in proportion to the input image data. Current applied to the line flows through the scan line during the PAM section.

The image data unit 120 outputs image data, and the average calculator 130 receives image data from the image data unit 120 and calculates an average of the image data to be applied to the scan line.

At this time, since the image data and the PAM driving waveform are proportional, the magnitude of the voltage generated in the scan line can be estimated using the average value of the average calculator 130, and the crosstalk is adjusted by adjusting the voltage of the precharge voltage or the current applied to the data line. Can be corrected.

The precharge current control unit 140 controls the current level of the precharge using the average output from the average calculator 130.

The precharge current controller 140 subtracts the correction data (G (x) of FIG. 3) using the average value output from the average calculator 130 and multiplies the result by the current set by the bias controller 150 to output the precharge current. Do it.

는 1부터 n까지의 영상데이터의 합 (X₁ + X₂ + X₃ + ... + Xn)을 n으로 나눈 것을 의미하는 것이고, 상기 평균값을 이용한 보정데이터는 수식 (나)로 표현되며, 수식 (나)에 표시된 β는 수식 (나)의 레지스터 값을 의미한다.That is, as shown in FIG. 3, the average value output from the average calculator 130 is expressed by equation (a), and in equation (a), 'Xi' is the 'i' th output to the image data unit 120. 'N' refers to the total number added by sigma (Σ), a mathematical term that simply indicates the same kind of numerical sum, and is an unknown number commonly used to represent an unlimited number. Means starting from 1 ', average value

Denotes the sum of the image data from 1 to n (X ₁ + X ₂ + X ₃ + ... + Xn) divided by n, and the correction data using the average value is expressed by the formula (B), Β in Equation (b) means the register value of Equation (b).

The bias controller 150 controls the bias by setting a current level of the data line. The data driver 160 outputs driving data for driving the OLED panel 180 by modulating the image data output from the image data unit 120 into a PAM driving waveform.

The driver controller 170 outputs the driving data through the data driver 160 according to the current level of the data line set by the bias controller 150 and the current level of the precharge controlled by the precharge current controller 140. Control 160.

The passive matrix OLED panel is driven by the scan signal output from the scan driver 110 and the drive data output from the data driver.

Meanwhile, the current waveform of the A / B / C region in the precharge current controller shown in FIGS. 1 to 3 will be described with reference to FIGS. 4 to 7. FIG. 4 is a precharge voltage according to an embodiment. FIG. 5 is a diagram illustrating a voltage / current level in an A / B / C region and a current applied to the OLED. FIG. 5 is a diagram illustrating a result of image correction according to the current characteristics shown in FIG. 4, and FIG. FIG. 7 is a diagram illustrating a voltage / current level in an A / B / C region and a current applied to an OLED in the precharge current controller according to the embodiment, and FIG. 7 illustrates a result of image correction according to the current characteristics shown in FIG. 6. Drawing.

As shown in FIG. 4, the precharge voltage is lowered by lowering the precharge current in the precharge section of the B region by using the equation (B) of FIG. 3. As a result, VSCAN_ON 'is lowered and VSEG is reduced, thereby reducing the phenomenon in which the parasitic capacitor current is discharged through the OLED, so that the amount of OLED current in the region B is similar to the amount of current in the region A / C as shown in FIG. To reduce crosstalk.

As shown in FIG. 6, the precharge voltage is increased by increasing the precharge current in the precharge section of the region B using the equation (b) of FIG. 3. Therefore, as VSCAN_ON 'is increased and VSEG is increased, the current is charged in the parasitic capacitor, thereby reducing the amount of OLED current in the B region to have a value similar to that of the A / C region as shown in FIG. Decrease.

Therefore, by controlling the precharge current for each scan line, the crosstalk generated in the passive matrix OLED panel is significantly reduced.

Those skilled in the art to which the present invention pertains will understand that the present invention can be implemented in other specific forms without changing the technical spirit or essential features. Therefore, the above-described embodiments are to be understood as illustrative in all respects and not as restrictive.

As described above, the present invention reduces the difference in voltage generated in each scan line by controlling the precharge current when each scan line is driven by using the average of image data input for each scan line of the passive matrix OLED panel. Crosstalk can be significantly reduced by reducing the difference in voltage generated across the OLED line by line.

In addition, the present invention prevents the reduction of the yield by avoiding the characteristic change of the analog circuit in the manufacture of the OLED driver IC by modifying only the digital part without modification of the existing analog circuit.

Claims (4)

In a crosstalk compensation device of a passive matrix OLED, A scan driver for outputting a scan signal; An image data unit for outputting image data; An average calculator for calculating an average of the image data to be applied to the scan line by calculating an average of the image data output from the image data unit; A precharge current controller for controlling the current level of the precharge using the average output from the average calculator; A bias control unit for setting a current level of the data line; A data driver configured to output driving data for driving the OLED panel by modulating the image data output from the image data unit into a PAM driving waveform; A driver controller controlling the data driver to output the driving data through a data driver according to a current level of a data line set by the bias controller and a current level of a precharge controlled by the precharge current controller; And Passive matrix OLED panel driven by the scan signal output from the scan driver and the drive data output from the data driver; Crosstalk compensation device of a passive matrix OLED comprising a. The method of claim 1, The precharge current controller subtracts correction data using the average value output from the average calculator to output a precharge current and multiplies it by the current set by the bias controller to output the crosstalk compensation device of the passive matrix OLED. . The method of claim 2, The average value output from the average calculator is represented by the following formula (a), and the correction data using the average value is represented by the formula (b) below Crosstalk compensation device of the passive matrix OLED.

The method of claim 1, The data line generates a PAM driving waveform from 0 to 63 in proportion to the input image data, and when the scan line is turned on, current applied to all data lines flows through the scan line during the PAM period. Crosstalk Compensator of Matrix OLED.

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