JP2006267766A - Active matrix organic light emitting diode driving control circuit with capability of dynamically adjusting white balance and adjustment method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving control circuit with the capability of dynamically adjusting the white balance of an active matrix organic light emitting diode display panel. <P>SOLUTION: A programmable voltage generator 430 generates programmable voltage sources such as Vdd_r and Vss_r, Vdd_g and Vss_g, and Vdd_b and Vss_b and serves as power sources for driving red (R), green (G), and blue (B) pixels within a display panel 450. A timing control circuit 440 is coupled to a gate driving circuit 410, a source driving circuit 420, and the programmable voltage generator 430 for controlling the timing of the submission of video data between the gate driving circuit 410 and the source driving circuit 420. Voltage values of the programmable voltage sources Vdd_r and Vss_r, Vdd_g and Vss_g, and Vdd_b and Vss_b are dynamically adjusted according to the usage status of the display panel, such as a display time and the number of pixels having gray levels higher than a fixed value. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an active matrix organic light emitting diode (AMOLED) drive control circuit and a drive method. In particular, the present invention relates to an active matrix organic light emitting diode (AMOLED) drive control circuit capable of dynamically adjusting white balance and a method for adjusting the same.

  With the rapid development of semiconductor manufacturing technology, various types of information processing apparatuses such as personal computers, mobile phones, portable information terminals, and digital cameras have been developed. In information equipment, one of the most important elements is a display device. Flat panel displays have become one of the most popular display products because they are lightweight and thin and consume less power.

  Active matrix organic light emitting diode (AMOLED) displays are a unique type of flat panel display that has many advantages including wide viewing angle, good color contrast, fast response and low production cost. Currently, many devices that require small displays such as electronic watches, mobile phones, personal digital assistants and digital cameras use AMOLED displays.

  However, because the materials in organic light emitting diodes that produce red (R), green (G), and blue (B) light are different, the brightness level of each color may change with long-term use. Eventually, the white balance of the OLED display panel may decrease. FIG. 1 shows luminance level curves for the lifetime of three types of high molecular weight luminescent materials to produce red, green and blue light. In FIG. 1, the bright curve shows the decay over time of the luminance levels of red, green and blue high molecular weight luminescent materials. It is clear that the decay rates over time of the three high molecular weight luminescent materials are not identical. The luminance level of each color changes after a certain period of time, thereby causing a decrease in white balance on the display panel.

  Accordingly, at least one object of the present invention is to provide an active matrix organic light emitting diode (AMOLED) driving control circuit capable of dynamically adjusting the white balance of an active matrix organic light emitting diode (AMOLED) display panel according to usage conditions, and a method for adjusting the same. Is to provide.

  To achieve these and other advantages, the present invention is capable of driving an active matrix organic light emitting diode (AMOLED) display panel, as implemented and broadly described herein according to the purpose of the present invention. An active matrix organic light emitting diode (AMOLED) driving control circuit and an active matrix organic light emitting diode (AMOLED) driving control circuit capable of dynamically adjusting the white balance of an active matrix organic light emitting diode (AMOLED) display panel are provided. The AMOLED drive control circuit includes a gate drive circuit, a source drive circuit, a programmable voltage generator, and a timing control circuit. The gate driving circuit generates a horizontal scanning signal for controlling the scanning line display of the AMOLED display panel. The source driving circuit is integrated with the horizontal scanning signal and transmits the video data of the display scanning line to the AMOLED display panel. The programmable voltage generator generates a plurality of programmable power supplies that function as power supplies for red, green and blue pixels in the AMOLED display. The timing control circuit is connected to the gate driving circuit, the source driving circuit, and the programmable voltage generator, and controls the timing of video data between the gate driving circuit and the source driving circuit. Depending on the usage state of the AMOLED display panel, the timing control circuit dynamically adjusts the voltage value of the programmable power supply. This also adjusts the white balance of the AMOLED display panel.

  In one embodiment of the present invention, the timing control circuit further includes a source and gate timing data control circuit, an interface processing circuit, and a white balance adjustment circuit. The source and gate timing data control circuit controls the timing of video data between the gate driving circuit and the source driving circuit. The interface processing circuit functions as a signal transmission interface. The white balance adjustment circuit is connected to the source and gate timing data control circuit and the interface processing circuit. The white balance adjustment circuit sets an adjustable parameter for changing the voltage value of the programmable power supply according to the usage state of the AMOLED display panel, and sends the parameter to the programmable voltage generator via the interface processing circuit.

  In one embodiment of the present invention, the use state or the degree of material deterioration of the AMOLED display panel is determined by whether or not the gray level displayed in the video data within the set period exceeds a preset value such as 255. . Based on the determination result, the value of the adjustable parameter for setting the voltage value of the programmable power supply is determined. Therefore, the white balance adjustment circuit includes at least a first comparator, a counter, a second comparator, an AND logic unit, and a parameter setting unit.

  The first comparator compares the video data with the preset data value and produces a first comparison signal. If the displayed gray level of the input video data is greater than or equal to the preset data value, a first comparison signal is sent. A counter for holding the count value is connected to the first comparator, whereby the count value is increased by, for example, 1 when the first comparison signal is received. The second comparator is connected to the counter, compares the count value registered by the counter with the preset count value, and generates a second comparison signal. When the number of displayed gray levels of video data equal to or greater than the preset value reaches the set count value, a second comparison signal is sent. The AND logic unit is connected to the second comparator and generates an adjustment signal in accordance with the second comparison signal after a predetermined period. The parameter setting unit is connected to the AND logic unit, sets an adjustable parameter for changing the voltage value of the programmable power supply according to the adjustment signal, and sends the parameter value to the programmable power supply via the interface processing circuit.

  The preset data value, preset count value, and preset time period described above can be stored in a read-only memory, an electrically erasable / programmable read-only memory, or a flash memory. The interface processing circuit described above can be a serial transmission interface such as IIC.

  The present invention also provides a method for dynamically adjusting the white balance of an active matrix organic output (AMOLED) display panel using an AMOLED drive control circuit. The method includes the following steps. First, a plurality of programmable power supplies are provided that function as power supplies for driving red, green, and blue pixels within the AMOLED display panel. Thereafter, the voltage values of various programmable power supplies are dynamically adjusted according to the usage state of the AMOLED display panel.

  The method for adjusting the voltage value of the programmable power supply according to the usage state of the AMOLED display panel receives video data and compares the video data with a preset data value. If the video data is greater than or equal to the preset data value, that is, if the displayed gray level of the video data is greater than or equal to 255 preset data values, the value in the counter is incremented by one. Thereafter, the value registered by the counter is compared with the preset count value. If the preset time period has elapsed and the value in the counter is greater than or equal to the preset time value, this indicates that the degradation level of the substance in the display panel has already exceeded an acceptable level. Therefore, to obtain better white balance in AMOLED display panel, the voltage value of the programmable power supply is adjusted.

  Therefore, the AMOLED drive control circuit and the adjustment method of the present invention can dynamically adjust the white balance of the AMOLED display panel according to the deterioration degree of the light emitting material in the panel. Therefore, the AMOLED display panel can obtain better and long-term white balance.

  The foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the invention as claimed.

  In order to describe the preferred embodiments of the present invention in detail, reference numerals are used in the examples shown in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.

  The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings, together with the description, illustrate embodiments of the invention and illustrate the principles of the invention.

  FIG. 2 is an equivalent diagram illustrating a pixel circuit of an active matrix organic light emitting diode in an AMOLED display panel. As shown in FIG. 2, the active matrix organic light emitting diode (AMOLED) pixel includes a first transistor 210, a second transistor 220, a capacitor 230, and an organic light emitting diode 240. The gate terminal of the first transistor 210 is connected to the scanning line, and the drain terminal of the first transistor 210 is connected to the data line. The source terminal of the first transistor 210 is connected to one terminal of the capacitor 230 similarly to the gate terminal of the second transistor 220. The drain terminal of the second transistor 220 is connected to the power supply Vdd, and the source terminal of the second transistor 220 is connected to the anode of the organic light emitting diode 240.

  When the horizontal scanning signal is applied to the pixel via the scanning line, the transistor 210 is turned on, so that the data line voltage Vg is applied to the gate terminal of the second transistor 220. In general, the luminance level of the organic light emitting diode 240 is proportional to the current Id flowing through the organic light emitting diode 240. Therefore, the displayed gray level of the organic light emitting diode 240 can be controlled by the voltage value indicating the video data of the data line.

  When an AMOLED display panel is used for a long time (see Figure 1), the brightness levels of red, green and blue light will degrade the high molecular weight luminescent material to produce red, green and blue light. There is a possibility to change due to the difference. Non-uniformity in the brightness levels of the three primary colors often results in white balance problems. In the present invention, in order to adjust the magnitude of the current Id flowing through the organic light emitting diode 240, the voltage of the power source Vdd in FIG. 2 can be reset. Thereby, the actual luminous intensity of the organic light emitting diode 240 can be changed. The effect of adjusting the supply voltage can be observed from the characteristic current with respect to the voltage curve of the transistor shown in FIG.

  FIG. 4 is a circuit diagram of an AMOLED drive control circuit for dynamically adjusting the white balance of an AMOLED display panel according to an embodiment of the present invention. As shown in FIG. 4, the AMOLED drive control circuit includes a gate drive circuit 410, a source drive circuit 420, a programmable voltage generator 430, and a timing control circuit 440. The AMOLED drive control circuit drives an array of red (R), green (G) and blue (B) pixels in the AMOLED display panel 450.

  The gate driving circuit 410 generates a horizontal scanning signal for controlling scanning lines of the AMOLED display panel 450. The source driving circuit 420 gives a source signal in accordance with video data intended for display and sends it to pixels corresponding to the horizontal scanning lines in the AMOLED display panel 450. The programmable voltage generator 430 generates a plurality of programmable power supplies such as Vdd_r and Vss_r, Vdd_g and Vss_g, and Vdd_b and Vss_b. These power supplies function as power supplies for red (R), green (G), and blue (B) pixels in the AMOLED display panel 450. The timing control circuit 440 is connected to the gate driving circuit 410, the source driving circuit 420, and the programmable voltage generator 430 and controls the timing of video data presentation between the gate driving circuit 410 and the source driving circuit 420. Depending on the usage time of the AMOLED display panel 450 such as the display time and the number of pixels having a gray level greater than a fixed value, the voltages of the programmable power supplies Vdd_r and Vss_r, Vdd_g and Vss_g, and Vdd_b and Vss_b Adjusted. Thereby, an ideal white balance is always maintained in the AMOLED display panel 450.

  FIG. 5 is a block diagram of a timing control circuit according to one embodiment of the present invention. As shown in FIG. 5, the timing control circuit 440 includes a source and gate timing data control circuit 510, an interface processing circuit 530, and a white balance adjustment circuit 520. The source and gate timing data control circuit 510 controls video data presentation timing between the gate driving circuit 410 and the source driving circuit 420. The interface processing circuit 530 provides a serial transmission interface such as IIC that functions as an interface for signal transmission. The white balance adjustment circuit 520 connected to the source and gate timing data control circuit 510 and the interface processing circuit 530 is an AMOLED display such as the number of pixels having a displayed gray level greater than a fixed value and the display time. It is used to adjust parameters for setting the voltage value of the programmable power supply according to the usage state of the panel. Thereafter, the white balance adjustment circuit 520 sends a parameter for changing the voltage value to the programmable voltage generator 430 via the interface processing circuit 530.

  FIG. 6 shows a display panel having a resolution of 1024 × 768 partitioned into 16 regions. According to the circuits shown in FIGS. 4 and 5 and the AMOLED drive control circuit of the present invention, the voltage of the programmable power supply is, for example, the display time and the number of pixels having a displayed gray level higher than a fixed value. Adjusted based on. The white balance adjustment circuit 520 can accurately set the voltage value of the programmable power source in order to measure the driving state or the deterioration degree of the luminescent material of the AMOLED display panel more accurately. Divided into regions. Each region counts the number of active matrix organic light emitting diodes that are at a displayed gray level greater than a fixed value within a specified period. Therefore, the collected data functions as a basis for determining the deterioration degree of the luminescent material. It is obvious to those skilled in the field that the AMOLED display panel can be divided into a desired number of counting areas.

  FIG. 7 is a circuit diagram of a white balance adjustment circuit according to one embodiment of the present invention. As shown in FIG. 7, the white balance adjustment circuit includes at least a first comparator 710, a counter 720, a second comparator 730, an AND logic unit 740, and a parameter setting unit 750. It is clear that the first comparator 710, the counter 720, the second comparator 730 and the AND logic unit 740 are used to determine the state of the preset time period and the preset count value in one area of the AMOLED display panel. It is. In order to detect the situation of more areas, it is necessary to increase the number of comparators and counters accordingly.

  In FIG. 7, the first comparator 710 is used to compare the displayed video data with a preset data value such as 255 and generate a first comparison signal C1. The first comparison signal C1 is produced when the displayed gray level of the input video data is greater than or equal to the preset data value signal. Here, if a preset data value having a gray level of 255 is used as a reference, all 8-bit displayed video data having the maximum degree of degradation of the material can be detected.

  Further, the counter 720 is connected to the first comparator 710, and updates the count value in the counter 720 when the first comparison signal C1 arrives. For example, when the comparison signal C1 is received from the first comparator 710, the count value in the counter 720 increases by one. The second comparator 730 is connected to the counter 720, compares the count value in the counter 720 with the preset count value, and generates a second comparison signal C2. That is, the second comparator 730 checks to determine whether the number of displayed video data having a gray level equal to or higher than the preset data value exceeds the preset count value. The AND logic unit 740 is connected to the second comparator 730, and generates the adjustment signal ADJ according to the second comparison signal C2 after the preset period has elapsed. The parameter setting unit 750 is connected to the AND logic unit 740 and adjusts the parameter for setting the voltage value of the programmable power supply according to the adjustment signal ADJ, and then the programmable voltage via the interface processing circuit 530. Send parameters to generator 430.

  In this embodiment, the preset data value, the preset count value, and the preset time period can be stored in, for example, a read-only memory (ROM), an electrically erasable / programmable read-only memory (EEPROM), or a flash memory. . In addition, all these values are read from the memory and function as comparison data each time the AMOLED display panel is driven.

  FIG. 8 illustrates a process for dynamically adjusting the white balance of an AMOLED display panel using an AMOLED drive control circuit according to one embodiment of the present invention. This method can dynamically adjust the white balance of the AMOLED display panel. First, a plurality of programmable power supplies are provided that function as power supplies for red, green and blue pixels in the AMOLED display panel. Thereafter, the voltage values of various programmable power supplies are dynamically adjusted according to the usage state of the AMOLED display panel. The AMOLED display panel described above is divided into 16 regions. Since the steps performed in each region for adjusting the pixels are the same, FIG. 8 shows the steps for adjusting the pixels only in the first region.

  In step 810, video data is obtained from the outside. In step 820, the video data is checked to determine which region in the AMOLED display panel it belongs to. Thereafter, the flow is divided depending on which region the obtained video data belongs to. For example, if it is determined that the video data belongs to the first region of the AMOLED display panel, step 830 is executed to compare the video data with preset data having a gray level of 255. If the video data is greater than or equal to the preset data value, step 840 is executed and the count value is increased. In step 850, the count value is compared with the preset count value, and if the preset value limit has elapsed, it is determined whether or not the count value is smaller than the preset count value. If the count value exceeds the preset count value after the preset time limit has elapsed, it is considered that the deterioration of the luminescent material in the AMOLED display panel has exceeded the allowable value. In this case, step 860 is performed to adjust the voltage values of the various programmable power supplies to provide an AMOLED display panel with better white balance. It is clear that the preset time limit and preset count value as reference values can be changed according to actual requirements. Further, a set of preset time limits and a set of preset count values can be used.

  It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the above, the present invention includes modifications and variations of the present invention which fall within the scope of the following claims and their equivalents.

Figure 5 shows luminance level curves versus lifetime for three types of high molecular weight luminescent materials for producing red, green and blue light. It is an equivalent diagram showing a pixel circuit of an active matrix organic light emitting diode. FIG. 3 is a diagram showing a characteristic curve of a transistor in the circuit shown in FIG. 2. FIG. 3 is a circuit diagram of an AMOLED drive control circuit for dynamically adjusting the white balance of an AMOLED display panel according to an embodiment of the present invention. 2 is a block diagram of a timing control circuit according to one embodiment of the present invention. FIG. It is a figure which shows the display panel which has the resolution of 1024x768 divided into 16 area | regions. It is a circuit diagram of the white balance adjustment circuit by one embodiment of this invention. 4 is a flowchart illustrating a process for dynamically adjusting the white balance of an AMOLED display panel using an AMOLED drive control circuit according to an embodiment of the present invention.

Explanation of symbols

210 first transistor 220 second transistor 230 capacitor 240 organic light emitting diode 410 gate driving circuit 420 source driving circuit 430 programmable voltage generator 440 timing control circuit 450 AMOLED display panel 510 source and gate timing data control circuit 520 white balance adjustment circuit 530 Interface processing circuit 710 First comparator 720 Counter 730 Second comparator 740 AND logic unit 750 Parameter setting unit

Claims (9)

A gate driving circuit for generating a horizontal scanning signal to control a scanning line of an active matrix organic light emitting diode (AMOLED) display panel;
A source driving circuit for adding video data to the AMOLED display panel in response to the horizontal scanning signal;
A programmable voltage generator for generating a plurality of programmable power supplies that function as power supplies for driving the red, green and blue pixels in the AMOLED display panel;
An active matrix organic light emitting diode (AMOLED) drive control circuit comprising the gate drive circuit, the source drive circuit, and a timing control circuit connected to the programmable voltage generator;
The timing control circuit controls the presentation timing of the video data between the gate driving circuit and the source driving circuit, and dynamically sets a voltage value of the programmable power source according to a usage state of the AMOLED display panel. An active matrix organic light emitting diode (AMOLED) drive control circuit for dynamically adjusting the white balance of an active matrix organic light emitting diode (AMOLED) display panel.   The timing control circuit includes a source and gate timing data control circuit for controlling the timing of presentation of the video data between the gate driving circuit and the source driving circuit, an interface processing circuit as a signal transmission interface, Connected to the source and gate timing data control circuit and the interface processing circuit, and adjusts the parameter for setting the voltage value of the programmable power source according to the use state of the active matrix organic light emitting diode (AMOLED) display panel 2. An active matrix organic light emitting diode according to claim 1, further comprising a white balance adjustment circuit for presenting the parameter to the programmable voltage generator via the interface processing circuit. (AMOLED) drive control circuit.   The white balance adjustment circuit compares at least the video data with a preset data value, generates a first comparison signal, and is connected to the first comparator, and the count value is based on the first comparison signal. And a counter connected to the counter, which compares the count value with a preset count value and generates a second comparison signal, and is connected to the second comparator, and the elapse of a preset time period An AND logic unit that generates an adjustment signal based on the second comparison signal later, and the parameter connected to the AND logic unit to set the voltage value of the programmable power supply according to the adjustment signal; A parameter setting unit that sends the parameter to the programmable voltage generator via the interface processing circuit. The active-trix organic light-emitting diode (AMOLED) drive control circuit according to claim 2.   4. The active matrix organic light emitting diode (AMOLED) drive control circuit according to claim 3, wherein the preset data value, the preset count value, and the preset time period are stored in a read-only memory unit.   4. The active matrix organic light emitting diode (AMOLED) according to claim 3, wherein the preset data value, the preset count value, and the preset time period are stored in an electrically erasable / programmable read-only memory. Drive control circuit.   4. The active matrix organic light emitting diode (AMOLED) drive control circuit according to claim 3, wherein the preset data value, the preset count value, and the preset time period are stored in a flash memory unit.   The active matrix organic light emitting diode (AMOLED) drive control circuit according to claim 2, wherein the interface processing circuit includes a serial transmission interface. Provide multiple programmable power supplies that function as power supplies to drive the red, green and blue pixels in the AMOLED display panel,
An active matrix organic light emitting diode (AMOLED) using an AMOLED driving control circuit that dynamically adjusts a voltage value of the programmable power source according to a use state of the active matrix organic light emitting diode (AMOLED) display panel A method for dynamically adjusting the white balance of the display panel. Dynamically adjusting the voltage value of the programmable power source according to the usage state of the active matrix organic light emitting diode (AMOLED) display panel receives video data and compares the video data with a preset data value If the video data is greater than or equal to the preset data value, the value in the counter is increased, the counter value is compared with a preset count value, and if the count value is greater than or equal to the preset count value, a preset time period 9. The adjustment method according to claim 8, wherein the voltage value of the programmable power supply is adjusted after elapse of time.

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