TW202147292A - Pixel compensation method of OLED display panel and information processing device using the same capable of instantly and dynamically adjusting the Demura pixel compensation table written into a flash memory at factory - Google Patents

Abstract

The present invention mainly discloses a pixel compensation method of an OLED display panel, which is applied to a display panel driver chip, so that the display panel driver chip can instantly and dynamically adjust the Demura pixel compensation table written into a flash memory at factory according to the current degradation and aging degree of the pixels of the OLED display panel. In addition, after the display panel driver chip is powered off, the dynamically updated Demura pixel compensation table will be written into the flash memory to achieve the function of automatically updating the pixel compensation table. Therefore, according to the dynamically updated Demura pixel compensation table, the display panel driver chip can not only eliminate the original Mura phenomenon of the display panel driver chip, but also correspondingly eliminate a new Mura phenomenon derived from the degradation of the organic material of the pixel.

Description

Pixel compensation method of OLED display panel and information processing device using the same

The present invention relates to the technical field of OLED displays, in particular to a pixel compensation method for an OLED display panel, which can effectively eliminate various traces caused by uneven pixel brightness in the OLED display panel.

It is known that a flat panel display includes a non-self-luminous flat panel display and a self-luminous flat panel display, wherein a liquid crystal display is a non-self-luminous flat panel display that has been used for a long time, and an organic light-emitting diode (OLED) ) display is a self-luminous flat panel display that is widely used at present. Compared with liquid crystal displays, OLED displays have many advantages, including: high contrast ratio, ultra-thin, flexible and so on.

The OLED display mainly includes a display panel driving chip, a flash memory and an OLED display panel. Due to material differences and/or process errors in the production process, some OLED display panels may exhibit the so-called Mura phenomenon. Among them, Mura refers to the phenomenon of various traces caused by uneven brightness of pixels in the OLED display panel.

At present, the Demura method is widely used to eliminate the Mura phenomenon of the OLED display panel, which provides a Demura pixel compensation table in the flash memory for the display panel driver chip to load and use to execute a pixel Compensation works to eliminate the Mura phenomenon. The conventional Demura method includes the following steps: (1) using a high-resolution and high-precision CCD camera to collect the panel screen brightness of the OLED display; (2) analyzing the color distribution characteristics of each pixel based on the collected data, and The relevant algorithm calculates the Mura data; (3) generates a Demura pixel compensation table according to the Mura data and the corresponding Demura compensation algorithm, and writes the Demura pixel compensation table into the flash memory; (4) again Collect the panel screen brightness of the OLED display to confirm that the Mura phenomenon has been eliminated.

However, the aforementioned Demura pixel compensation table will only be written into the flash memory once when the OLED display leaves the factory, and will not be changed or modified after that. It must be known that the OLED display panel uses organic light-emitting materials as its red sub-pixels (Sub-pixel), green sub-pixels and blue sub-pixels, and one pixel (Pixel) is lit with high brightness for a long time. In this case, the organic light-emitting material will age due to Degradation, resulting in a decrease in its luminous efficiency, so that the pixel cannot display the specified brightness under the same driving current, and finally the OLED display panel will appear uneven in light emission.

It is further explained that since each sub-pixel has a different degree of loss after long-term use, when a fixed high-brightness static image is displayed for a long time, new image afterimages are prone to appear on the OLED display panel. Considered the new Mura phenomenon. Practical experience shows that the Demura pixel compensation table written into the flash memory at the factory cannot effectively eliminate the aforementioned new Mura phenomenon.

It can be seen from the above description that there is an urgent need in the art for a new pixel compensation method for an OLED display panel.

The main purpose of the present invention is to provide a pixel compensation method for an OLED display panel, which is applied to a display panel driver chip, so that the display panel driver chip can instantly, Dynamically adjust the Demura pixel compensation table that is written into the flash memory at the factory to effectively eliminate the Mura phenomenon.

In order to achieve the above object, the present invention proposes the pixel compensation method of the OLED display panel, which is applied in a display panel driving chip, and includes:

(1) after the display panel driver chip is powered on, load a previous decay count value from an external memory into an internal memory of the display panel driver chip;

(2) Divide the OLED display panel into X display blocks, calculate a block average grayscale value of each of the display blocks, and further calculate the average grayscale value of each of the blocks and the panel average A difference between the grayscale values is divided by the average grayscale value of the panel to obtain X block decay rates; wherein each of the display blocks includes a plurality of pixels, and X is a positive integer;

(3) Record at least one display block whose block decay rate exceeds a threshold, and calculate a compensation count and a temperature of the recorded display block through interpolation and table lookup methods coefficient, so as to calculate a decay count increase value corresponding to the recorded display block according to the compensation count, the temperature coefficient and a current backlight rate of the OLED display panel;

(4) Perform an addition operation on the previous fading count value and the fading count increment value to obtain a current fading count value, and then use the interpolation method and the look-up table method to calculate at least three fading compensation rates), so as to obtain at least three fading compensation rates according to at least performing a pixel compensation operation on the OLED display panel for three of the decay compensation rates; and

(5) After the display panel driving chip is powered off, write the current fade count value into the external memory to replace and become the previous fade count value.

In one embodiment, the threshold is at least 0.5.

In one embodiment, the block average grayscale value and the block average grayscale value of each of the display blocks are collected by performing a pixel luminance collection operation on the OLED display panel according to a fixed collection frequency, so as to be collected. Calculated.

In one embodiment, each of the compensation counts is calculated using interpolation and a first look-up table, and the first look-up table includes a plurality of the block decay rates and corresponding to a plurality of the block decay rates. rate of a plurality of the compensation counts.

In one embodiment, the temperature coefficients are obtained by calculation using interpolation and a second look-up table, and the second look-up table includes a plurality of the temperature coefficients and a plurality of temperature coefficients corresponding to the plurality of temperature coefficients. panel temperature.

In one embodiment, the decay count increment value is obtained by sequentially performing a multiplication operation and an integer processing on the compensation count, the temperature coefficient and the current backlight rate.

In one embodiment, at least three of the fading compensation rates are calculated and obtained by using an interpolation method and corresponding at least three pixel compensation tables, and the at least three pixel compensation tables are stored in the external memory , and each of the pixel compensation tables includes a plurality of the fading compensation rates and a plurality of fading count values corresponding to the plurality of the fading compensation rates.

In one embodiment, the external memory is a flash memory, and the internal memory is a random access memory.

The present invention also provides an information processing device having the OLED display as described above.

In a feasible embodiment, the information processing device is an electronic device selected from the group consisting of a smart phone, a tablet computer, a notebook computer, an all-in-one computer, a smart watch and an access control device.

In order to enable your examiners to further understand the structure, characteristics, purpose, and advantages of the present invention, drawings and detailed descriptions of preferred embodiments are attached as follows.

The principle of the present invention is: the OLED display panel of the present invention enables a display panel driver chip to instantly and dynamically update a Demura pixel compensation table according to the current pixel decay and aging degree of the OLED display panel, and the display panel driver chip After power off, write back the updated Demura pixel compensation table to a flash memory to achieve the effect of automatically updating the pixel compensation table. Specifically, the OLED display panel of the present invention is characterized in that: an external memory can be provided to store a plurality of previous fading compensation rates of a pixel array of an OLED display panel; according to the plurality of previous fading compensation rates, a temperature coefficients and a current backlight rate of the OLED display panel to calculate a plurality of fading compensation rate increments, and perform an addition operation on the plurality of previous fading compensation rates and the plurality of fading compensation rate increments to obtain a plurality of current fading compensation rates fading compensation ratios; and writing the plurality of current fading compensation ratios into the external memory to update the plurality of previous fading compensation ratios after the display panel driving chip is powered off.

Please refer to FIG. 1 , which shows a structural diagram of an OLED display applying a pixel compensation method for an OLED display panel of the present invention. As shown in FIG. 1 , the OLED display 1 mainly includes a display panel driving chip 11 , an OLED display panel 12 and an external memory 13 . It should be known that the OLED display panel 12 includes a plurality of pixels, and each pixel includes at least three sub-pixels. FIG. 2 is a graph showing the service life of an OLED display panel of the OLED display of the present invention for pixel operation at different grayscale values. After observing FIG. 2 , it should be found that for each pixel that displays different brightness for a long time, the degree of aging of the organic light-emitting material due to degradation is also different. In more detail, a pixel displaying a high grayscale value for a long time has a significantly higher degradation ratio than a pixel displaying a low grayscale value for a long time.

It must be noted that the Demura method is widely used to eliminate the Mura phenomenon of the OLED display panel 12, which provides a Demura pixel compensation table in the external memory 13 (ie, flash memory) for the After the display panel driving chip 11 is powered on, it is loaded into an internal memory 111 thereof, so that a pixel compensation operation is performed on the OLED display panel chip 12 using the Demura pixel compensation table to eliminate the Mura phenomenon. The internal memory 111 is a random access memory (Random Access Memory, RAM). Please also refer to FIG. 3 , which shows a data graph of a Demura pixel compensation table stored in the external memory 13 of the OLED display 1 of the present invention. In general, each pixel included in the OLED display panel 12 is composed of red sub-pixels, green sub-pixels and blue sub-pixels, so the Demura is stored in the external memory 13 There are three pixel compensation tables.

However, after the OLED display 1 has been used for a period of time, the deterioration and/or aging of the organic light-emitting material may cause the aforementioned Demura pixel compensation table to fail to effectively eliminate the new Mura phenomenon. Therefore, the present invention proposes a pixel compensation method for an OLED display panel, which is applied to a display panel driving chip 11 , so that the display panel driving chip 11 can perform real-time and dynamic compensation according to the current aging degree of the pixels of the OLED display panel 12 . It adjusts the Demura pixel compensation table written in the external memory 13 when it leaves the factory, and effectively eliminates the Mura phenomenon.

FIG. 4 shows a flowchart of a pixel compensation method for an OLED display panel according to the present invention. As shown in FIG. 4 , when the OLED display 1 works normally, the pixel compensation method of the OLED display panel of the present invention firstly executes step S1 : after the display panel driving chip 11 is powered on, a previous decay count value is calculated. Loaded from an external memory 13 into an internal memory 111 of the display panel driving chip 11 . The foregoing description has already explained that the external memory 13 stores the Demura pixel compensation table written at the factory. Therefore, it should be understood that the so-called “previous decay count value” is the horizontal line in the data graph shown in FIG. 3 . Coordinate data. For example, if the previous degradation count value (Degradation_count) is 20000, the corresponding (luminance) degradation compensation ratio (D_ratio) is 1.2.

As shown in FIG. 1 and FIG. 4 , after loading the previous decay count value, the method flow then executes step S2 : dividing the OLED display panel 12 into X display blocks 121 , and calculating each of the display blocks 121 The average gray-scale value of a block of the Block (luminance) decay rate. Wherein, each of the display blocks 121 includes a plurality of pixels, and X is a positive integer.

Continuing, the method flow then executes step S3: recording at least one of the display blocks 121 whose block decay rate exceeds a threshold, and calculating the recorded display area through interpolation and table lookup A compensation count and a temperature coefficient of block 121 are obtained, and a current backlight rate of the OLED display panel 12 is obtained, so as to calculate the display block corresponding to the recorded display block according to the compensation count, the temperature coefficient and the current backlight rate One of 121 Degradation count increment value (Degradation_count_add). For example, the threshold value is 0.5, but not limited thereto. In short, the display blocks 121 with the block decay rate higher than 0.5 (ie, 50%) will be recorded, that is, these display blocks 121 need to perform pixel compensation.

In more detail, the above-mentioned block average grayscale value and the block average grayscale value of each of the display blocks 121 are performed on the OLED display panel 12 according to a fixed acquisition frequency for a pixel brightness acquisition operation, so as to be collected. Calculated. Wherein, the fixed collection frequency is, for example, once per minute, but not limited thereto. It is worth noting that the pixel brightness collection operation is accomplished by using a light sensing unit including a photodiode, a CMOS camera, a CCD camera, or an ambient light sensor group. For example, for the OLED display 1 integrated in a smart phone and/or a tablet computer, the display panel 12 further includes a plurality of photodiodes, and the plurality of photodiodes are used for connecting with a fingerprint detection chip Cooperate to achieve under-screen fingerprint sensing. Therefore, the photodiodes can be controlled to perform a pixel luminance collection operation on the OLED display panel 12 according to a fixed collection frequency, so as to complete the average grayscale value of the block, the average grayscale value of each block, and X A calculation of the decay rate of the block.

Please refer to FIG. 5 , which shows a data graph of a first look-up table used in the pixel compensation method of the OLED display panel of the present invention. When step S3 is performed, each of the compensation counts is obtained by calculation using an interpolation method and a first look-up table. As shown in FIG. 5 , the first lookup table includes a plurality of the block decay rates and a plurality of the compensation counts corresponding to the plurality of the block decay rates. For example, when the calculated block decay rate is 1.25, two values of compensation counts corresponding to the block decay rate of 1.0 and 1.5 can be found through the first look-up table, and then use the internal The interpolation method can calculate the value of the compensation count corresponding to the block decay rate of 1.25.

Please also refer to FIG. 6 , which shows a data graph of a second look-up table used in the pixel compensation method of the OLED display panel of the present invention. When step S3 is performed, the temperature coefficient is obtained by calculation using an interpolation method and a second look-up table. As shown in FIG. 6 , the second look-up table includes a plurality of the temperature coefficients and a plurality of panel temperatures corresponding to the plurality of the temperature coefficients. For example, when the current panel temperature measured by the temperature sensor is 30°C, two values of the temperature coefficient corresponding to the panel temperatures of 20°C and 40°C can be found through the second lookup table , and then the value of the temperature coefficient corresponding to the current panel temperature of 30°C can be calculated by the interpolation method.

On the other hand, the current backlight ratio used in the aforementioned step S3 is Ratio of digital brightness value (DBV), that is, the current value of the backlight adjusting bar in the function options of the general OLED display 1 . After obtaining the correlation value of the compensation count, the temperature coefficient and the current backlight rate, the degradation count increase value (Degradation_count_add) can perform a multiplication operation in sequence by the compensation count, the temperature coefficient and the current backlight rate obtained by processing with an integer.

After calculating the degradation count increase value (Degradation_count_add), the method flow then executes step S4: performing an addition operation on the previous decay count value and the decay count increase value to obtain a current decay count value, which is then used together At least three fading compensation ratios (D_ratio) are calculated by the interpolation method and the look-up table method, so as to perform a pixel compensation operation on the OLED display panel 12 according to the at least three fading compensation ratios. In more detail, the mathematical formula (1): Degradation_count(current)=Degradation_count(previous)+Degradation_count_add is used to calculate the so-called "current decay count value".

As shown in FIG. 3 , if the previous fading count value is 20000, the corresponding (luminance) fading compensation rate can be found in the Demura pixel compensation table shown in FIG. 3 . Further, if the incremental value of the decay count is 5000 after real-time and dynamic calculation, the current decay count value of 25,000 can be obtained after calculation using the aforementioned mathematical formula (1). At this time, looking up the Demura pixel compensation table shown in FIG. 3 , it can be seen that when a fade count value is 30000, the corresponding (brightness) fade compensation rate is 1.4. Therefore, for the current fading count value of 25000, the corresponding (brightness) fading compensation rate can be calculated by interpolation to be 1.3. In more detail, since a pixel includes at least a red sub-pixel, a green sub-pixel and a blue sub-pixel, in step S4, at least three of the fading compensation rates are interpolated and corresponding At least three Demura pixel compensation tables are thus calculated. It can be seen from FIG. 3 that each of the Demura pixel compensation tables includes a plurality of the degradation compensation ratios (D_ratio) and a plurality of degradation counts (Degradation_count) values corresponding to the plurality of the degradation compensation ratios.

After completing the pixel compensation operation, for the pixels included in one of the display blocks 121 of the OLED display panel 12 for displaying amber, the RGB grayscales are compensated by (255, 191, 0), for example. is (255,191+1,0). Or, for the pixels included in one of the display blocks 121 of the OLED display panel 12 for displaying Chartreuse, the RGB grayscale is compensated by (127, 255, 0) to (127+, for example) 2,255,0).

As shown in FIG. 1 and FIG. 4 , after the pixel compensation operation is completed, the method flow finally executes step S5 : after the display panel driving chip 11 is powered off, the current decay count value is written into the external memory 13 . , to replace and become the previous decay count value. In other words, when the OLED display 1 works normally next time, the host processor (eg, GPU) transmits an input image to the image buffer unit 112 of the display panel driving chip 11 . At this time, the processing unit 113 of the display panel driving chip 11 executes the pixel compensation method of the OLED display panel of the present invention and executes step S1: after the display panel driving chip 11 is powered on, the previous decay count value is stored in the external memory 13 is loaded into the internal memory 111 of the display panel driving chip 11, and then steps S2-S5 are repeated. With this design, for the display panel driving chip 11 integrated with the pixel compensation method of the OLED display panel of the present invention, after power-on, the display panel driving chip 11 can be adjusted according to the current degradation aging degree of the pixels of the OLED display panel 11 . Real-time and dynamic adjustment of the Demura pixel compensation table that is written into the flash memory at the factory, and then perform a block of pixel compensation on the OLED display panel 11 according to the dynamically updated Demura pixel compensation table, Ultimately effectively eliminates the new/old Mura phenomenon.

In this way, the above has completely and clearly described a pixel compensation method for an OLED display panel of the present invention; and, from the above, it can be known that the present invention has the following advantages:

(1) The present invention discloses a pixel compensation method for an OLED display panel, which is applied to a display panel driving chip, so that the display panel driving chip can perform real-time and dynamic compensation according to the current degradation and aging degree of the pixels of the OLED display panel. It adjusts the Demura pixel compensation table that is written into the flash memory at the factory, and effectively eliminates the Mura phenomenon.

(2) The present invention also discloses an information processing device having an OLED display to which the pixel compensation method of the OLED display panel of the present invention is applied as described above. Moreover, the information processing device can be a smart phone, a tablet computer, a notebook computer, an all-in-one computer, a smart watch, or an access control device.

It must be emphasized that the above-mentioned disclosure in this case is a preferred embodiment, and any partial changes or modifications originating from the technical ideas of this case and easily inferred by those who are familiar with the art are within the scope of the patent of this case. category of rights.

To sum up, regardless of the purpose, means and effect of this case, it shows that it is completely different from the conventional technology, and its first invention is practical, and it does meet the patent requirements of the invention. Society is to pray for the best.

1: OLED display 11: Display panel driver chip 111: Internal memory 112: Image buffer unit 113: Processing unit 12: OLED display panel 121: Display block 13: External memory S1: After the display panel driver chip is powered on, load a previous decay count value from an external memory into an internal memory of the display panel driver chip S2: Divide the OLED display panel into X display blocks, and calculate a block average grayscale value of each of the display blocks, and further divide the average grayscale value of each of the blocks and the panel average grayscale value A difference between the grayscale values is divided by the average grayscale value of the panel to obtain X block decay rates; S3: Record at least one of the display blocks whose block decay rate exceeds a threshold, and calculate a compensation count and a temperature coefficient of the recorded display block through interpolation and table lookup , so as to calculate a decay count increase value corresponding to the recorded display block according to the compensation count, the temperature coefficient and a current backlight rate of the OLED display panel S4: Perform an addition operation on the previous fading count value and the fading count increment value to obtain a current fading count value, and then use the interpolation method and the look-up table method to calculate at least three fading compensation rates, so as to calculate at least three fading compensation rates according to at least three The fading compensation rate performs a pixel compensation operation on the OLED display panel S5: After the display panel driving chip is powered off, write the current decay count value into the external memory to replace and become the previous decay count value

FIG. 1 is a structural diagram of an OLED display applying a pixel compensation method for an OLED display panel of the present invention; FIG. 2 is a graph showing the service life of an OLED display panel of the OLED display of the present invention for pixel operation at different grayscale values; 3 is a data graph of a Demura pixel compensation table stored in an external memory of the OLED display of the present invention; 4 is a flowchart of a pixel compensation method for an OLED display panel according to the present invention; 5 is a data graph of a first look-up table used in the pixel compensation method of the OLED display panel of the present invention; and FIG. 6 is a data graph of a second lookup table used in the pixel compensation method of the OLED display panel of the present invention.

S1: After the display panel driver chip is powered on, load a previous decay count value from an external memory into an internal memory of the display panel driver chip

S2: Divide the OLED display panel into X display blocks, and calculate a block average grayscale value of each of the display blocks, and further divide the average grayscale value of each of the blocks and the panel average grayscale value The difference between the grayscale values is divided by the average grayscale value of the panel, so as to obtain the decay rate of X blocks

S3: Record at least one of the display blocks whose block decay rate exceeds a threshold, and calculate a compensation count and a temperature coefficient of the recorded display block through interpolation and table lookup , so as to calculate a decay count increase value corresponding to the recorded display block according to the compensation count, the temperature coefficient and a current backlight rate of the OLED display panel

S4: Perform an addition operation on the previous fading count value and the fading count increment value to obtain a current fading count value, and then use the interpolation method and the look-up table method to calculate at least three fading compensation rates, so as to calculate at least three fading compensation rates according to at least three The fading compensation rate performs a pixel compensation operation on the OLED display panel

S5: After the display panel driving chip is powered off, write the current decay count value into the external memory to replace and become the previous decay count value

Claims (10)

A pixel compensation method for an OLED display panel, which is applied to a display panel driving chip, and includes: After the display panel driving chip is powered on, a previous decay count value is loaded from an external memory into an internal memory of the display panel driving chip; The OLED display panel is divided into X display blocks, and the average grayscale value of a block of each of the display blocks is calculated, and the average grayscale value of each of the blocks and the average grayscale value of the panel are further calculated. A difference between the two is divided by the average grayscale value of the panel to obtain X block decay rates; wherein each of the display blocks includes a plurality of pixels, and X is a positive integer; Record at least one of the display blocks whose decay rate of the blocks exceeds a threshold, and calculate a compensation count and a temperature coefficient of the recorded display blocks through interpolation and table lookup, thereby calculating a decay count increase value corresponding to the recorded display block according to the compensation count, the temperature coefficient and a current backlight rate of the OLED display panel; Perform an addition operation on the previous fading count value and the fading count increment value to obtain a current fading count value, and then use an interpolation method and a look-up table method to calculate at least three fading compensation rates, so as to calculate at least three The fading compensation rate performs a pixel compensation operation on the OLED display panel for one block; and After the display panel driving chip is powered off, the current decay count value is written into the external memory to replace and become the previous decay count value. The pixel compensation method for an OLED display panel according to claim 1, wherein the threshold value is at least 0.5. The pixel compensation method for an OLED display panel according to claim 1, wherein the block average grayscale value and the block average grayscale value of each of the display blocks are based on a fixed collection frequency for the OLED The display panel performs a pixel brightness acquisition operation, so as to be calculated. The pixel compensation method for an OLED display panel according to claim 1, wherein each of the compensation counts is obtained by calculation using an interpolation method and a first look-up table, and the first look-up table includes a plurality of the blocks A decay rate and a plurality of said backoff counts corresponding to a plurality of said block decay rates. The pixel compensation method for an OLED display panel according to claim 1, wherein the temperature coefficient is obtained by calculation using an interpolation method and a second look-up table, and the second look-up table includes a plurality of the temperature coefficients and a plurality of panel temperatures corresponding to a plurality of said temperature coefficients. The pixel compensation method for an OLED display panel according to claim 1, wherein the increment of the decay count is performed by sequentially performing a multiplication operation and an integer processing on the compensation count, the temperature coefficient and the current backlight rate and obtained. The pixel compensation method for an OLED display panel according to claim 1, wherein at least three of the decay compensation rates are obtained by calculation using an interpolation method and at least three corresponding pixel compensation tables, and the at least three A pixel compensation table is stored in the external memory, and each of the pixel compensation tables includes a plurality of the fading compensation rates and a plurality of fading count values corresponding to the plurality of the fading compensation rates. The pixel compensation method for an OLED display panel according to claim 1, wherein the external memory is a flash memory, and the internal memory is a random access memory. A pixel compensation method for an OLED display panel, which is applied to a display panel driving chip, and is characterized by comprising: providing an external memory for storing a plurality of previous fade compensation rates of a pixel array of an OLED display panel; calculating a plurality of fading compensation rate increments according to the plurality of previous fading compensation rates, a temperature coefficient and a current backlight rate of the OLED display panel, and calculating the plurality of previous fading compensation rates and the plurality of fading compensation rates performing an addition operation on the rate increment values to obtain a plurality of current decay compensation rates; and After the display panel driving chip is powered off, the plurality of current fading compensation rates are written into the external memory to update the plurality of previous fading compensation rates. An information processing device, which has the OLED display according to any one of claim 1 to claim 9, and the information processing device is composed of a smart phone, a tablet computer, a notebook computer, an all-in-one computer, a smart watch An electronic device selected by the group consisting of an access control device.

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