KR20030090861A - Apparatus and Method for controlling A Gamma data automatically - Google Patents

Abstract

PURPOSE: An automatic gamma control system and method are provided to automatically adjust a panel driving voltage level for gamma control using a predetermined optimal target luminance level and a luminance level deviation measured according to light transmission characteristic of a panel. CONSTITUTION: An automatic gamma control system includes a voltage supply(20) for supplying a voltage corresponding to a specific gradation of an RGB color signal, an A/D converter(21) for converting the voltage into a digital signal level, a gamma memory(22) for mapping the digital signal level with a panel driving voltage level, and a D/A converter(23) for converting the panel driving voltage level into an analog signal. The automatic gamma control system further includes a display module(30) for displaying an input image according to the panel driving voltage, a luminance measurement unit(24) for measuring the luminance voltage level of the displayed image, a gamma data calculator(25) for comparing the measured luminance voltage level with a predetermined target luminance voltage level to calculate gamma data according to the comparison result, and a microcomputer(26) for maintaining or rewriting the panel driving voltage level stored in the gamma memory.

Description

Apparatus and Method for controlling A Gamma data automatically}

The present invention relates to an automatic gamma adjustment device and method for automatically adjusting a level value of a panel driving voltage for gamma adjustment by using a predetermined optimum target luminance level and a deviation of the luminance level measured according to the light transmission characteristics of the panel. It is about.

In general, in a display device using an LCD, which has recently been rapidly commercialized, the gamma characteristic correction of the LCD module is one of the very important technical problems to improve the image quality by utilizing the gradation of contrast. Instead, the corrected value was adjusted by repeated adjustment of the instrument at the discretion of the microcomputer or only a skilled technician.

Fig. 1 is a view showing a general gamma characteristic adjusting apparatus using a microcomputer among them.

As shown in the drawing, if the gamma correction unit 10 gamma corrects an R / G / B color signal input under the control of the microcomputer 15 in units of a predetermined signal level, and then outputs the gamma correction unit 10 to the panel driver 11. In addition, the panel driver 11 drives the panel 12 according to the corresponding R / G / B color signal output so that a specific image is displayed, and the luminance meter 13 measures the luminance according to the signal level of the displayed image. .

Then, when the microcomputer 14 compares the difference between the desired target luminance characteristic and the luminance characteristic measured after gamma correction and outputs the result to the gamma correction unit 10, the gamma correction unit 10 is inputted. The gamma correction of the R / G / B color signal is performed on a signal level interval basis in accordance with the output comparison result. This operation is repeatedly performed until it matches or approaches a desired target characteristic under the control of the microcomputer 10.

However, since the adjustment method of the R / G / B color signal is performed in units of a predetermined signal level, the luminance characteristic of the R / G / B color signal according to the panel characteristics does not exactly match the desired target luminance characteristic. Is not easy.

In other words, although gamma correction is controlled by a microcomputer, the target luminance characteristic of each R / G / B color signal can be accurately corrected for each corresponding gradation by relying on an approach for changing the signal level up or down over a predetermined interval. There is a limit to gaining.

For example, if the gamma characteristic correction curve is as shown in FIG. 2, the gamma correction apparatus analogically approached as described above changes the transmission characteristics by dividing each section, but does not subdivide the sections more finely than this time. Not only is it difficult to approximate the desired brightness characteristics, but it is also difficult to fine-tune the hardware characteristics by constructing the hardware for the correction of analog signals, and also the gray level between products generated by the gamma characteristic deviation of each panel during mass production. There was a problem that the adjustment to overcome the characteristic deviation is actually very difficult.

Accordingly, the present invention is to solve the above-mentioned problems, and digitally calculates the level value of the panel driving voltage for gamma adjustment by using a deviation between the optimum target luminance level and the luminance level measured according to the light transmission characteristics of the panel. It is an object of the present invention to provide an automatic gamma adjustment device for automatic adjustment.

To this end, the present invention supplies a voltage corresponding to a specific gray level of the R / G / B color signal, digitally converts it to a corresponding level value, and then maps and stores the level value of the corresponding level value and the panel driving voltage in advance. Outputs the level value of the specific panel driving voltage mapped to the, converts the output level value of the panel driving voltage into an analog signal, displays an input image according to the panel driving voltage, and then displays the luminance voltage level of the displayed image. The target luminance voltage levels stored in advance may be compared to maintain or rewrite the level values of the stored panel driving voltages using gamma data calculated according to the comparison result.

1 is a view showing a general gamma adjusting device,

2 is a diagram illustrating a general gamma correction characteristic curve,

3 is a view showing the automatic gamma adjustment device of the present invention,

4A and 4B are diagrams showing an example of a storage mode of gamma data applied to the present invention.

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

20: voltage supply unit 21: A / D conversion unit

22: gamma memory unit 23: D / A conversion unit

24: luminance meter 25: gamma data calculation unit

26: microcomputer 30: display module

31 optical engine 32 panel driver

33: panel

Hereinafter, the present invention will be described with reference to the accompanying drawings.

First, the automatic gamma adjusting device of the present invention includes: a voltage supply unit 20 for supplying a voltage corresponding to a specific gray level of an R / G / B color signal; An A / D converter 21 for converting the supplied voltage into a digital signal level value; A gamma memory unit 22 which maps and stores the digital signal level value and the level value of the panel driving voltage in advance; A D / A converter 23 for converting the level value of the stored panel driving voltage into an analog signal; A display module 30 for displaying an input image according to the converted panel driving voltage; A luminance meter 24 for measuring the luminance voltage level of the image to be displayed; A gamma data calculator 25 for comparing the measured luminance voltage level with a predetermined target luminance voltage level and calculating gamma data according to the comparison result; The microcomputer 26 automatically adjusts the level value of the panel driving voltage stored in the gamma memory unit 22 according to the calculated gamma data.

The display module 30 includes a panel driver 32 for driving an R / G / B primary color signal output from the optical engine 31 according to the panel driving voltage output from the D / A converter 23; The panel 33 is configured to display an image under the control of the panel driver 32.

The automatic gamma adjustment device of the present invention thus made comprises a first panel drive voltage corresponding to a value (hereinafter, abbreviated as " gradation value ") in which the specific gray level of the R / G / B color signal is represented as digital data in the gamma memory unit 22. The digital signal level value (hereinafter, abbreviated as "panel value") is stored in advance.

In this case, the gamma memory unit 22 is preferably configured with a lookup table, and the lookup table is configured with, for example, an EPROM, and particularly, the output is configured with a 10-bit memory, which is a gamma data calculator. This is to allow the microcomputer 26 to rewrite the panel values in accordance with the gamma data calculated in (25) and to maintain the rewritten panel values.

In this state, under the control of the microcomputer 26, a voltage corresponding to a specific gray level of the R / G / B color signal is supplied through the voltage supply unit 20, and the gray level which is digital data by the A / D conversion unit 21. When converted to a value, the gamma memory unit 22 outputs a panel value corresponding to a specific gray value of each converted R / G / B color signal.

That is, when the gray value of each R / G / B color signal supplied by the voltage supply unit 20 is converted into a gray value which is n bits of digital data through the A / D converter 21, the gamma memory unit 22 Outputs a panel value corresponding to each grayscale value of n bits.

For example, when the gray value of each R / G / B color signal is configured to have 8 bits and is supplied to the gamma memory unit 22, the gamma memory unit 22 corresponds to one to one corresponding to the gray value of each color signal. The panel value is converted into a panel value of a bit and outputted. In this case, the panel value is a value measured in advance through a luminance level characteristic experiment of the corresponding panel.

Subsequently, the data output from the gamma memory 22 is supplied to the D / A converter 23 and converted into an analog signal, and then output to the panel 33, which is a display unit, through the panel driver 32.

In this case, it is preferable that the D / A converter 23 is configured such that the output step width of 1 bit is changed. Accordingly, the D / A converter 23 may vary the amplitude of the panel value to the set gain. It is desirable to have gain setting means, and the panel driver 32 preferably includes offset setting means for superposing a DC component with respect to an output voltage and varying an offset level.

Meanwhile, the voltage converted into the analog signal drives the panel driver 32, and the driven panel driver 32 outputs the R / G / B primary color signal output from the optical engine 31 through the display module. .

Subsequently, the luminance meter 24 measures the luminance level of the output R / G / B primary color signal and applies the same to the gamma data calculator 25 through an Isquare bus line.

Then, the gamma data calculator 25 compares the measured luminance level with a target luminance voltage level previously stored in an internal memory (not shown), and calculates gamma data according to the comparison result.

That is, as a result of the comparison, if the two luminance levels are the same, the panel values stored in the gamma memory unit 22 are kept as they are. If not, the gamma data corresponding to the difference between the two target luminance levels is calculated and then calculated. Adjust panel values by data.

The microcomputer 26 rewrites the adjusted panel value into the gamma memory unit 22 to display system characteristics having target luminance level characteristics, which will be described below in detail with reference to embodiments of the present invention.

First, in the automatic gamma adjusting apparatus of the present invention, when the R color signal is divided into 16 gray levels, the voltage supply unit 20 generates a corresponding voltage of gray scales (hereinafter referred to as "first gray scale") that are expressed in the darkest brightness. Supply to the A / D conversion section 21.

Then, the A / D converter 21 converts the supplied voltage of the first grayscale into a corresponding digital signal level value (hereinafter, abbreviated as "first grayscale value") and applies it to the gamma memory unit 22. .

The " first gradation value " thus applied is addressed to the level value of the corresponding panel driving voltage (hereinafter abbreviated as " first panel value ") mapped to the first gradation value under the control of the microcomputer 26. And output.

In this case, the mapping relationship between the first grayscale value and the first panel value is an optimal relationship derived through experiments and the like is preset and stored in the gamma memory unit 22. For example, as shown in FIG. 4A. same.

That is, as shown in FIG. 4A, the "gradation value" that is the digital signal level value of the voltage corresponding to the specific gray level is defined as "V _x ", and the "panel value" that is the digital signal level value of the panel driving voltage as V _y . case, the first gray level value from the 16 gradation value _{V x1, V x2, ...,} V x16, the first panel from the value of the panel 16 a value V _{y1, y2} V, ..., are mapped to V ₁₆ .

At this time, the first to sixteenth gray values (V _x1 , V _x2 , ..., V _x16 ,) are declared as static variables so that the set value does not change and always preserves the previous value. It is desirable to.

An example of a process of initially setting the gray and panel values in the lookup table is as follows.

First, a corresponding address 100 is assigned to “V _x1 ”, which is the uppermost layer of the lookup table, and “V _y1 ” mapped to V _x1 is linked with a pointer so as to break down.

That gives the following "V _x1" bottom layer, _{"V x2""Vx15"} 1 increased by address from the address 101 indicates that the layer to each of the data field to 115 up from the.

In the same manner as described above, the address of the corresponding data field in which the "V _x2 " to "V _x15 " are stored, and the "V _y1 ", ... "V _y15 respectively mapped to the" V _x2 "to" V _x15 " Link the address of the data field of "with a pointer.

That is, the gradation and panel values from the highest tier to the lowest tier are stored in the corresponding data field, each address is assigned to the storage location, and the gradation is linked to the address of the panel value mapped thereto. In this case, the entire luminance level of the R / G / B color signal can be sequentially measured for each corresponding gray level.

On the other hand, if the first panel value mapped to the first gray scale value under the control of the microcomputer 26 is output to the D / A converter 23 through the gamma memory unit 22, the output first panel value is The first panel drive voltage is converted into an analog signal.

The converted first panel driving voltage drives the panel driver 32, and the driven panel driver 32 outputs a predetermined size R (red) primary color signal output from the optical engine 31 through the display module. .

Then, the luminance level of the output R signal, that is, the luminance level of the R signal corresponding to the first grayscale value is measured by the luminance meter 24 and applied to the gamma data calculator 25 through the Isquare bus line.

Then, the gamma data calculator 25 compares the luminance level applied through the luminance meter 24 with a target luminance voltage level stored in a memory (not shown) in advance, and gamma according to the comparison result. Calculate the data.

The first panel value stored in the gamma memory unit 22 is maintained or rewritten using the calculated gamma data. An example of this will be described with reference to FIG. 4B.

At this time, "V _x " shown in FIG. 4B represents the aforementioned "gradation value", "T '" represents a predetermined target luminance level, and "V' _y " represents a desired panel value, respectively.

And, V _x1 , V _x2 , ..., V _x16 are the first gray value, the second gray value, ..., the sixteenth gray value, T ' ₁ , T' ₂ , ..., T _'16 Is the first target luminance level, the second target luminance level, ..., the 16th target luminance level, V ' _y1 , V' _y2 , ..., V ' _y16 is the first desired panel value, the second desired panel Value, ..., 16th desired panel value.

At this time, the target luminance levels that categorize the primary color signal R to the 16 gray levels, the _{T '1, T' 2,} ..., T '16 are each V' _y1, V _'y2, ..., V 'Mapped to _y16 and stored.

In this stored state, the first luminance measurement level T ₁ measured by the luminance meter 24 is compared with the first target luminance level T ′ ₁ stored in the lookup table.

As a result of the comparison, if the two luminance levels are the same, the first panel value V _y1 stored in the gamma memory unit is maintained as it is; otherwise, the gamma data corresponding to the difference between the two target luminance levels V _y1 and V ' _y1 is maintained. After calculating, the calculated gamma data is rewritten by increasing or decreasing the calculated gamma data to the first panel value V _y1 .

When the rewriting is finished, the voltage corresponding to the second grayscale of the R color signal is supplied through the voltage supply unit 20 under the control of the microcomputer 26, and then the above-described operation is repeatedly performed to obtain the luminance of the second grayscale. Measure the level.

Then, the measured luminance level of the second grayscale is compared with the previously stored second target luminance level, and the second panel value stored in the gamma memory unit 22 is adjusted according to the comparison result.

When the luminance level adjustment corresponding to the 16 gradations of the R color signal is terminated through this method, the panel value adjustment is performed for each gradation value of the G / B color signal, and the optimal panel value is rewritten to the gamma memory unit, whereby the target luminance characteristic is increased. It will have the system characteristics shown.

Next, another automatic gamma adjustment method of the present invention will be described.

First, when the R color signal is classified into 16 gray levels, a corresponding voltage of the first gray level represented by the darkest brightness is generated, and the corresponding voltage of the generated first gray level is converted into a first gray value which is a corresponding digital signal level value.

Subsequently, the first panel value mapped to the converted first gray scale value is addressed and output. The first panel value defines a digital signal level value of the panel driving voltage.

The mapping relationship between the first grayscale value and the first panel value is set in advance in a lookup table or the like, and a setting method thereof will be described with reference to FIG. 4A.

That is, as shown in FIG. 4A, when the first gray value is represented by "V _x1 " and the first panel value is represented by "V _y1 ", the value of V _x1 is declared as a static variable, It is desirable that the previous value is always kept unchanged and that V _y1 is declared as a (Dynamic) variable so that it can be varied according to the light transmission characteristics of the corresponding measured panel.

Next, the first gradation and panel values are initially set in the lookup table. First, "V _x1 " is stored in the data field representing the top layer of the lookup table, and the corresponding address 100 is assigned to the stored data field.

Then, "V _y1 " mapped to "V _x1 " is stored in the corresponding data field and the corresponding address 100.10 is assigned to the stored data field, where the corresponding address of "V _x1 " and "V _y1 " The bungee is linked with a pointer so that it breaks down.

Then, the storage by each mapping performed by the method described above repeatedly from "V _x2" in the lower layer of the "V _x1" to _"x15 V" from the _{"V y2""Vy15"} .

That is, the address the store from "V _x2" in the lower layer of the "V _x1" "V _x15" in the data field, and a from representing respectively the corresponding layer at a store data field address 101 by one to 115 counts increased After assigning the "V _x2 " to "V _x15 ", "V _y2 " to "V _y15 " is stored in the corresponding data field and "V _x2 " to "mapped to the address of the stored data field Link with the corresponding address of V _x15 ".

As a result, the values of "V _x2 " to "V _x15 " respectively mapped from the highest layer V _x1 to the lowest layer "V _x15 " are adjusted in order according to the count incremented by one.

Meanwhile, when a first panel value mapped to the first gray scale value is output, the output first panel value is converted into a first panel driving voltage in the form of an analog signal.

The converted first panel drive voltage drives the panel driver to display a predetermined level R (red) primary color signal output from the optical engine.

Next, the first luminance level of the displayed R primary color signal, that is, the luminance level of the R primary color signal corresponding to the first gray level is measured, and the "first luminance level" becomes the first gray level light transmitting characteristic of the corresponding panel.

Subsequently, the first luminance level is compared with a corresponding target luminance level, that is, the first target luminance voltage level previously stored in a separate memory.

Thus, the first panel value for driving the panel driver is automatically adjusted according to the comparison result, which will be described with reference to FIG. 4B.

In this case, "V _x " shown in FIG. 4B denotes the aforementioned "gradation value", "T '" denotes a target luminance level, and "V' _y " denotes a desired panel value corresponding to the target luminance level, respectively. It is shown.

And, V _x1 , V _x2 , ..., V _x16 are the first gray value, the second gray value, ..., the sixteenth gray value, T ' ₁ , T' ₂ , ..., T _'16 Is the first target luminance level, the second target luminance level, ..., the 16th target luminance level, V ' _y1 , V' _y2 , ..., V ' _y16 is the first desired panel value, the second desired panel Value, and the sixteenth desired panel value.

In this defined state, the first luminance measurement level measured by the luminance meter is compared with the first target luminance level stored in the lookup table.

As a result of the comparison, if the two luminance levels are the same, the first panel value V _y1 stored in the gamma memory unit is kept as it is; otherwise, the gamma data corresponding to the difference between the two target luminance levels V _y1 and V ' _y1 is maintained. After calculating, the calculated gamma data is increased and decreased to the first panel value V _y1 and rewritten.

Subsequently, when the rewriting of the first panel value is completed, the voltage corresponding to the second grayscale of the R color signal is supplied, and the above-described operation is repeatedly performed to measure the luminance level of the second grayscale.

Then, the measured luminance level of the second grayscale is compared with the previously stored second target luminance level, and the second panel value stored in the gamma memory unit is adjusted according to the comparison result.

In this way, when all the luminance level adjustments corresponding to the 16 gradations of the R color signal are completed, the same adjustment method as described above is repeatedly performed to adjust the G / B signal and store the optimal panel values in the lookup table. The characteristic becomes the same as the target luminance level characteristic.

As described in detail above, the automatic gamma adjustment apparatus and method thereof according to the present invention provide a luminance level measured by supplying a variable input voltage corresponding to each grayscale value of an R / G / B color signal and a predetermined optimal target luminance level. By rewriting the level value of the panel driving voltage stored in the lookup table using the deviation of, the gamma adjustment time can be reduced and the gray scale characteristic that increases linearly can be realized. There is an effect that an image quality suitable for the desired luminance level characteristic can be obtained.

Although the invention has been described in detail only with respect to the specific examples described, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (3)

A voltage supply unit supplying a voltage corresponding to a specific gray level of the R / G / B color signal; An A / D converter converting the supplied voltage into a digital signal level value; A gamma memory unit which maps and stores the digital signal level value and the level value of the panel driving voltage in advance; A D / A converter converting the level value of the stored panel driving voltage into an analog signal; A display module configured to display an input image according to the converted panel driving voltage; A luminance meter for measuring the luminance voltage level of the displayed image; A gamma data calculator for comparing the measured luminance voltage level with a predetermined target luminance voltage level and calculating gamma data according to the comparison result; And a microcomputer for maintaining or rewriting the level value of the panel driving voltage stored in the gamma memory unit in accordance with the calculated gamma data. The method of claim 1, wherein the gamma memory unit; Automatic gamma adjustment device characterized in that the look-up table (Look-up-table). Supplying a voltage corresponding to a specific gray level of the R / G / B color signal; Digitally converting the supplied voltage to a corresponding level value; Pre-mapped and storing the level value of the corresponding level value and the panel driving voltage, and outputting a level value of a specific panel driving voltage mapped to the level value; Converting the level value of the output panel driving voltage into an analog signal and displaying an input image according to the panel driving voltage; Measuring a luminance voltage level of the displayed image; Comparing the measured luminance voltage level with a previously stored target luminance voltage level and calculating gamma data according to the comparison result; And maintaining or rewriting the level value of the stored panel driving voltage in accordance with the calculated gamma data.