JP2009225440A - Liquid crystal picture display apparatus and white balance control method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal picture display apparatus and a white balance control method thereof, which displays color pictures using a liquid crystal panel to adjust white balance quickly. <P>SOLUTION: The liquid crystal picture display apparatus includes: a white balance control part which computes a ratio of red (R), green (G), and blue (B) when a picture is adjusted to a target white balance, changes a target intensity ratio characteristic, and adjusts the white balance according to the intensity ratio characteristics for adjustment; a gamma correction value recording device part which records gamma correction values of R, G, and B created in the white balance control part; and a target value storage device part which stores the target white balance and the target intensity ratio characteristic. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device that displays a color image using a liquid crystal panel and a white balance control method thereof.

  The configuration of this conventional liquid crystal display device has the following configuration.

  That is, a video display unit that displays and displays a video signal, a video signal control unit that generates a video signal used for white balance control and outputs an input video signal to be output to the video display unit, and an output projected on the screen The white chromaticity of the video signal, the light output detection unit that detects the respective luminances of R, G, and B, the luminance ratio of R, G, and B are controlled to a desired ratio, and the measured white chromaticity And a white balance control unit that feedback-adjusts the luminance ratio of R, G, and B so that the difference between the target values is equal to or less than a predetermined value. .

In this way, in the white balance control method in which the luminance ratio of R, G, and B is feedback adjusted so that the white balance becomes the target white, the number of times of feedback is reduced and the target white balance is quickly achieved. There is one in which approximate calculation means based on the Newton-Raphson method is introduced so that adjustment is possible (for example, Patent Document 1 below).
JP 2004-328386 A

  The problem with the conventional example is that it takes time to adjust the white balance.

  That is, in the above conventional example, it is measured whether the white chromaticity is the target value, and the luminance ratio of R, G, B is feedback adjusted so that the difference between the target values is not more than a predetermined value. Therefore, repeated control is required, and it takes time to adjust the white balance.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to quickly adjust white balance.

  In order to achieve this object, the present invention provides a video display unit that displays and displays a video signal, and a video signal control that generates a video signal used for white balance control and outputs an input video signal output to the video display unit. A light output detector that outputs the output video signal projected on the screen as a tristimulus value, or outputs data that can be converted into a tristimulus value, and a tristimulus value obtained from the light output detector, Alternatively, using the data obtained by converting the data obtained from the light output detector into tristimulus values, the ratio of R (red), G (green), and B (blue) when adjusted to the target white balance is calculated. A white balance control unit that changes the target luminance rate characteristic and adjusts the white balance according to the adjustment luminance rate characteristic, and R (red), G (green), and B (blue) generated by the white balance control unit The moth A gamma correction value recording unit that records Ma correction value, and the white balance of the target, the structure comprising a target value recording unit to be allowed to record the luminance factor characteristic of the target.

  This achieves the intended purpose.

  As described above, the present invention provides a video display unit that displays and displays a video signal, a video signal control unit that generates a video signal used for white balance control, and outputs an input video signal output to the video display unit, Outputs the output video signal projected on the screen as tristimulus values or outputs a light output detector that outputs data that can be converted to tristimulus values, and detects tristimulus values or light output obtained from the light output detector Using the data obtained by converting the data obtained from the tristimulus value to the tristimulus value, the ratio of R (red), G (green), and B (blue) when adjusted to the target white balance is calculated, and the target luminance rate The white balance control unit that changes the characteristics and adjusts the white balance according to the luminance ratio characteristic for adjustment, and the gamma correction values of R (red), G (green), and B (blue) generated by the white balance control unit Record Since the gamma correction value recording device unit and the target value recording device unit for recording the target white balance and the target luminance rate characteristic are configured, the white balance can be adjusted quickly. It is.

  That is, in the present invention, the white balance is not adjusted by feedback, and for each of R, G, and B, tristimulus values are measured for each predetermined luminance gradation, and calculation is performed by combining the measurement results. Since the white balance is adjusted by determining a combination that achieves a desired white balance for each reference luminance, the white balance can be adjusted quickly.

  Furthermore, the tristimulus values of five signals of white, red, green, blue with the maximum luminance and black with the minimum luminance are measured, and R (red), G that can be adjusted to the target white balance from the tristimulus values. The ratio of (green) and B (blue) is calculated, and the target luminance rate characteristic is changed according to the ratio. Since the white balance is adjusted according to the changed luminance rate characteristic and the target white balance, it is possible to perform a high-precision adjustment without degrading the contrast more than necessary and achieving a high gradation.

  Hereinafter, embodiments of the liquid crystal display device of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
In the first embodiment, specific white balance adjustment / control will be described. FIG. 1 shows a configuration diagram of a liquid crystal display device of the present invention.

  In the liquid crystal display device of the present invention, the light output detection unit 5 is installed at a position where the video signal can be detected on the video display unit 20 that displays and displays the video signal.

  The light output detection unit 5 is a sensor element that can measure tristimulus values of light or light information that can be converted into tristimulus values, such as chromaticity values and luminance. There is a video signal control unit 4 capable of projecting an arbitrary signal to the light output detection unit 5, and the video signal control unit 4 controls the white balance and luminance of the video with respect to the light output detection unit 5. A video signal necessary for the generation is generated and displayed on the video display unit.

  The video signals necessary for controlling the white balance are a white video signal indicating the maximum luminance, a maximum output of each signal of R (red), G (green), and B (blue), and a black video for indicating the minimum luminance. A video signal of the signal is generated by the video signal control unit 4 and displayed on the video display unit 20.

  The video signal is output from the light output detection unit 5 as tristimulus values corresponding to the video signal or information that can be converted into tristimulus values.

  The white balance control unit 6 receives this information, calculates the ratio of R (red), G (green), and B (blue) when the target white balance is adjusted, and changes the target luminance rate characteristic. The white balance is adjusted by adjusting the white balance according to the changed luminance rate characteristic and the target white balance.

  Information for controlling the white balance and luminance of the video is calculated by comparing with the white balance and luminance information recorded in advance in the target value storage unit 8. The calculated information for controlling the color and brightness of the video is called a gamma correction value, and there are gamma correction values for R (red), G (green), and B (blue). The gamma correction value is recorded in the gamma correction value storage unit 7 and is used by the video signal control unit 4 when displaying a television signal or the like.

  As a result, the liquid crystal display device of the present invention can quickly adjust the white balance.

  That is, in the present invention, the white balance is not adjusted by feedback, and for each of R, G, and B, tristimulus values are measured for each predetermined luminance gradation, and calculation is performed by combining the measurement results. Since the white balance is adjusted by determining a combination that achieves a desired white balance for each reference luminance, the white balance can be adjusted quickly.

  Furthermore, the tristimulus values of five signals of white, red, green, blue with the maximum luminance and black with the minimum luminance are measured, and R (red), G that can be adjusted to the target white balance from the tristimulus values. The ratio of (green) and B (blue) is calculated, and the target luminance rate characteristic is changed according to the ratio. Since the white balance is adjusted according to the changed luminance rate characteristic and the target white balance, it is possible to perform a high-precision adjustment without degrading the contrast more than necessary and achieving a high gradation.

Similarly, FIG. 2 shows a configuration diagram of a liquid crystal display device of the present invention.
A light source 1 is provided, and illumination light from the light source 1 is split into R (red), G (green), and B (blue) for projection.

The split three primary color lights and the video signal from the video signal control unit 4 are combined in the video conversion unit 2 and projected onto the screen 3 as video information output.
On the screen 3, a light output detector 5 is installed at a position where a video signal projected on the screen can be detected.

  The light output detection unit 5 is a sensor element that can measure tristimulus values of light or light information that can be converted into tristimulus values, such as chromaticity value and luminance.

  There is a video signal control unit 4 capable of projecting an arbitrary signal to the light output detection unit 5, and the video signal control unit 4 controls the white balance and luminance of the video with respect to the light output detection unit 5. A video signal necessary for this is generated and projected through the video converter 2.

  The video signal necessary for the control of the present invention is a white video signal indicating the maximum luminance of the apparatus, a maximum output of each signal of R (red), G (green), and B (blue), and a minimum luminance. The video signal of the black video signal is generated by the video signal control unit 4 and projected through the video conversion unit 2.

  The projected video signal is projected onto the light output detection unit 5, and the light output detection unit 5 outputs tristimulus values corresponding to the video signal or information that can be converted into tristimulus values.

  The white balance control unit 6 receives this information, calculates the ratio of R (red), G (green), and B (blue) when the target white balance is adjusted, and changes the target luminance rate characteristic. The white balance is adjusted by adjusting the white balance according to the changed luminance rate characteristic and the target white balance.

  Information for controlling the white balance and luminance of the video is calculated by comparing with the white balance and luminance information recorded in advance in the target value storage unit 8. The calculated information for controlling the color and brightness of the video is called a gamma correction value, and there are gamma correction values for R (red), G (green), and B (blue). The gamma correction value is recorded in the gamma correction value storage unit 7 and is used by the video signal control unit 4 when displaying a television signal or the like.

  As a result, the liquid crystal display device of the present invention can quickly adjust the white balance.

  That is, in the present invention, the white balance is not adjusted by feedback, and for each of R, G, and B, tristimulus values are measured for each predetermined luminance gradation, and calculation is performed by combining the measurement results. Since the white balance is adjusted by determining a combination that achieves a desired white balance for each reference luminance, the white balance can be adjusted quickly.

  Furthermore, the tristimulus values of five signals of white, red, green, blue with the maximum luminance and black with the minimum luminance are measured, and R (red), G that can be adjusted to the target white balance from the tristimulus values. The ratio of (green) and B (blue) is calculated, and the target luminance rate characteristic is changed according to the ratio. Since the white balance is adjusted according to the changed luminance rate characteristic and the target white balance, it is possible to perform a high-precision adjustment without degrading the contrast more than necessary and achieving a high gradation.

A flowchart of this white balance and luminance control method is shown in FIG.
The details of the white balance and luminance control method shown here will be described for the liquid crystal display device having the configuration shown in FIG.

  In the first step, a video signal necessary for white balance control is supplied from the video signal control unit 4 to the video conversion unit 2. This video signal is detected as a tristimulus value output or information that can be converted into a tristimulus value by the light output detector 5 that is projected and attached to the screen 3 as an output video signal. At this time, the output video signal is a white video signal indicating the maximum luminance, a maximum output of each signal of R (red), G (green), and B (blue), and a black video signal for indicating the minimum luminance. These output video signals are detected as tristimulus value output by the light output detector 5 or as information that can be converted into tristimulus values.

  When the maximum brightness of R (red), G (green), and B (blue) is used when adjusting the target white balance by the second step, R (red), G (green), B ( The ratio of blue) is calculated. This ratio indicates how much ratio R (red) and B (blue) are required for the maximum output of R (red) and B (blue) when the maximum output of G (green) is used as a reference. It becomes a parameter.

  For example, assuming that G (green) is 1 and R (red) is 1.3, when the transmittance of the G (green) liquid crystal panel is maximized and the dynamic range is fully used, R (red) requires 1.3 times the maximum output of R (red). However, it is naturally impossible to output more than the maximum output. Therefore, in order to accurately adjust the target white balance, it is necessary to lower G (green) relatively. If G (green) is lowered, the output of R (red) is relatively small.

  The Y stimulus value of the tristimulus value XYZ of G (green) occupies most of the luminance component of the device and greatly affects the luminance performance of the device. When the output of R (red) is insufficient when G (green) is used as a reference as described above, the output of G (green) is reduced, that is, the maximum brightness of the device is output by lowering the maximum brightness of the device. Even so, it means that the white balance is adjusted accurately.

  When contrast is prioritized and the G (green) dynamic range is fully used, the white balance does not accurately reach the target value under the above conditions.

  In the embodiment of the present invention, the ratio of the maximum output of R (red), G (green), and B (blue) for adjusting to the target white balance is obtained by calculation, thereby reducing G (green). The width, that is, the reduction in brightness and contrast of the apparatus is accurately and minimized. The calculation method is described in detail below.

  The signals necessary for the present invention are a white video signal indicating the maximum luminance of the apparatus, a maximum output of each signal of R (red), G (green), and B (blue), and a video signal of a black video signal for indicating the minimum luminance. The signal is generated by the video signal control unit 4 and projected through the video conversion unit 2 as described above, and the color information is acquired by the light output detection unit 5.

  The CIE chromaticity value of the white signal indicating the maximum luminance of the device is xn, yn. Tristimulus values are defined as Xn, Yn, Zn.

On the other hand, the target CIE chromaticity value is xc, yc. Tristimulus values are defined as Xc, Yc, and Zc.
The following relationship holds between the CIE chromaticity values x, y and the tristimulus values X, Y, Z.

  That is, it is as follows.

  Here, the relationship between xn, yn and xc, yc is defined as in Equations 7 and 8. A, B 'and C are constants.

  Furthermore, the maximum output tristimulus value of R (red) is XRn, YRn, ZRn. The tristimulus values of the maximum output of G (green) are XGn, YGn, ZGn. If the tristimulus values of the maximum output of B (blue) are expressed as XBn, YBn, ZBn, the following relations hold among the tristimulus values Xn, Yn, Zn of the white signal indicating the maximum luminance of the device.

  Here, assuming that X / Y, Y / Z, and X / Z of each color are constant in each gradation, only levels of R (red) and B (blue) are assumed to be variable. Each component is expressed as follows.

By solving the above five simultaneous equations of Equation 7, Equation 8, Equation 12, Equation 13, and Equation 14, D and E can be calculated.

  As described above, the maximum output of R (red) and B (blue) is the maximum output of R (red) and B (blue) when the maximum output of G (green) for adjusting to the target white balance is used as a reference. Thus, the parameters D and E indicating the ratio of the required values are obtained.

  That is, the tristimulus values XRn, XGn, XBn, YRn, YGn, YBn, ZRn, ZGn, and ZBn at the maximum output of the three colors of R (red), G (green), and B (blue) are measured to obtain values. Then, αR, αG, βG, βB, γR, γB are obtained by calculation and R (red) based on G (green) when the target white balance is obtained by performing calculations up to Equations 34 and 35, Ratios D and E with respect to each maximum output of B (blue) are obtained.

  However, if necessary, tristimulus values are subtracted from the tristimulus values when black indicating the minimum luminance is measured. This zero correction enables more accurate calculation.

  The target luminance rate characteristic is changed by the third step. The luminance rate characteristic is the ratio of the luminance of the white signal detected by the light output detection unit 5 to the signal input to the video signal control unit 4. That is, when the maximum value of the input signal is input, the detection luminance in the light output detection unit is also maximum. This is the ratio of the luminance up to 0% with the maximum luminance as 100%.

  In order to increase the maximum luminance of the device as much as possible, the luminance of the device is improved by maximizing the transmittance of the G (green) liquid crystal panel as described above. However, if the transmittance of the G (green) liquid crystal panel is maximized, the white balance adjustment may fail near the maximum brightness of the apparatus, and the target white balance may not be achieved.

  Therefore, when the input signal of 100% is input, if the maximum value of the target luminance rate characteristic is not 100% of the transmittance of the G (green) liquid crystal panel, it is an accurate white balance adjustment. The target luminance ratio characteristic is changed using the ratios D and E obtained in the second step. The target luminance rate characteristic prepared by default assumes that the maximum value of the target luminance rate characteristic is 100% of the transmittance of the G (green) liquid crystal panel when an input signal of 100% is input. Be prepared. This is the information that gives the best luminance performance as a device. This luminance rate characteristic is divided by a certain numerical value to lower the maximum transmittance of the G (green) liquid crystal panel. Of course, the ratio from 100% to 0% of the input signal is constant.

Here, a method of changing the target luminance rate characteristic will be described.
The ratio derived in the second step is based on the maximum output of G (green), and R (red) and B (blue) are relative to the maximum output of R (red) and B (blue). There are parameters D and E that indicate how much ratio is required.

  When the value of either D or E is 1 or more, the value of D or E is normalized by comparing D and E and dividing the default target luminance rate characteristic by a large value.

In other words, in order to be able to adjust to the target color temperature with the ratio calculated in the second step, the brightness of R (red), G (green), and B (blue) is regular so as not to exceed the maximum output. It is necessary to make it. The normalization can be performed by changing the luminance rate characteristic.
If the resulting luminance rate characteristic is "adjustment luminance rate characteristic"

It becomes.

  In the fourth step, white balance adjustment is performed using this adjustment luminance rate characteristic, so that accurate and accurate white balance can be obtained up to the maximum luminance of the apparatus.

  Next, FIG. 4 shows a flowchart for details of white balance adjustment.

  In the first step, a video signal necessary for white balance control (in this white balance control, a gamma correction value is generated, and brightness control is also performed simultaneously with consent) is sent to the video conversion unit 2 by video signal control. Supplied from section 4.

  In the second step, this video signal is detected as a tristimulus value output or information that can be converted into a tristimulus value by the light output detector 5 that is projected and attached to the screen 3 as an output video signal. At this time, the output video signal is a white video signal in which R (red), G (green), and B (blue) all indicate maximum luminance, and all of R (red), G (green), and B (blue) are minimum. Black video signal indicating luminance, R (red), G (green), B (blue) video signals and R (red) to indicate the maximum luminance of each of R (red), G (green), and B (blue) Red, G (green) and B (blue) are video signals of a plurality of points between R (red), G (green) and B (blue) video signals for indicating the minimum luminance. Is output as tristimulus value output by the light output detector 5 or as information that can be converted into tristimulus values.

  In the third step, the Y stimulus value among the G (green) tristimulus values is linearly complemented, converted into a target luminance rate characteristic, and the G (green) gamma correction value is calculated. The calculation method is described below.

  First, a function used in the calculation of the third step is defined.

Of the signals necessary for white balance control, the video signal between the maximum luminance and the minimum luminance is divided into a plurality of points. The plurality of points are set to 0, 1, 2 ... n ... n-max,
The input signal of the video signal control unit 4 is fi (n),
The output signal of the video signal control unit 4 is fo (n),
The gamma correction value for G (green) is G-Gamma (n).

For example, assuming that the signal input to the video signal control unit 4 is 10 bits and the output signal is 10 bits, and n-max is 64, the 10-bit signals of each input / output are divided into 64 equal parts.
Based on the above example, fi (64) = 1023
fo (64) = 1023
Since the gamma correction value is the look-up table data of the output signal fo with respect to the input signal fi to the video signal control unit 4, the output signal fo (n) of the G (green) video signal control unit 4 after the gamma correction is applied. It is expressed as shown in Equation 101.

  Further, the target luminance rate characteristic is recorded in the target value storage unit 8. The luminance rate characteristic is the ratio of the luminance of the white signal detected by the light output detector 5 to the signal fi (n) input to the video signal controller 4.

  Here, if the contents of the first step and the second step are supplemented, the video signal supplied to the video conversion unit 2 from the video signal control unit 4 necessary for white balance control, which is output in the first step. Is a video signal fo (n) from 0 point to “n-max” point of each RGB, and the discrete data detected in the second step is the dynamic range of the signal processed by the video signal processing unit. The video signal fo (n) output in the first step, which is discretely divided at multiple points from 0 to n-max, that is, the signal level is different for each point, outputs the light projected on the screen as light output The data measured by the detection unit 5 is obtained.

Among the G (green) tristimulus values obtained by measurement, the Y stimulus value is defined as LG (n). The value obtained by subtracting the value of LG (0) at the 0th point from LG (n) is referred to as L′ G (n).
L′ G (n) is defined as in Equation 102.

  Based on this number 102, among the G (green) tristimulus values, the G (green) transmittance characteristic represented by the Y stimulus value is defined as ftx (n), and the G (green) transmittance characteristic ftx (n) is expressed as shown in Equation 103.

(Number 103 is in units of (%))
The target luminance rate characteristic is expressed as ft (n) (%), where fi (n) is the input signal.
According to the following calculation formula, the Y stimulus value of the tristimulus value of G (green) is converted into the target luminance rate characteristic. The G (green) gamma correction value fo (n) is obtained by this calculation formula.
When determining the gamma correction value fo (n) of the “n” point, ft (n) and ftx (n) are compared to perform case classification. The calculation is performed in the direction of decreasing from n = max.
When ftx (n)> ft (n)
Compare ft (n) with ftx (n-1), ftx (n-2) ...
Find the value of α such that ft (n)> ftx (α). (Find the place where ftx (n)> ft (n) reverses)
The G (green) gamma correction value is calculated as shown in Equation 104.

If ftx (n) <ft (n)
Compare ft (n) with ftx (n + 1), ftx (n + 2) ...
A β value satisfying ft (n) <ftx (β) is obtained. (Search where ftx (n) <ft (n) reverses)
The gamma correction value for G (green) is calculated as shown in Equation 105.

When ftx (n) = ft (n), the G (green) gamma correction value is calculated as shown in Equation 106.

  As described above, the G (green) gamma correction value G-Gamma (n) is obtained by dividing the three cases for all points. Using the same calculation formula, the tristimulus value of G (green) at the “n” point is calculated. The tristimulus values stopped here are also used as reference data when calculating the white balance.

  By the fourth step, the tristimulus values of R (red) and B (blue) that become the target white balance for the tristimulus values of G (green) in a specific gradation “n” of G (green) are obtained. Calculation is performed with linear interpolation, and R (red) and B (blue) gamma correction values are calculated from the tristimulus values. The calculation method is described.

First, the CIE chromaticity indicating the target white balance value at the point “n” where the calculation for defining the parameter used in the calculation in the fourth step is performed is x (n) and y (n).

  In general, the relationship of Equation 107 and Equation 108 is established between CIE chromaticity x, y and tristimulus values X, Y, Z.

The chromaticity values xo (n) and yo (n) indicating the white balance at each adjustment point “n” are expressed by Equations 109 and 110.

  Here, XRl, YRl and ZRl are tristimulus values of R (red), and l is data obtained by linearly complementing the tristimulus values of R (red) obtained in the second step to the maximum resolution of fo. To do. If it is 10 bits, it is a value from 0 to 1023.

  For example, in the case of n-max = 64, the 10-bit signal is divided into 64 equal parts, and is divided by 16 steps in decimal conversion. Therefore, data of l (n) = 16 × n is measured by the second step. Here, values other than l (n) = 16 × n, for example, tristimulus values when l = 24 are tristimulus values when l (1) = 16 and tristimulus values when l (2) = 32. This is the middle data.

  Similarly, XBm, YBm, and ZBm are B (blue) tristimulus values, and m is data obtained by linearly complementing the B (blue) tristimulus values obtained in the second step to the maximum resolution of fo. . If it is 10 bits, it is a value from 0 to 1023. Therefore, the tristimulus value data obtained in the second step is a value obtained by calculating data for all fo using linear interpolation.

  Since the green tristimulus value of Point “n” has already been obtained by the calculation in the third step, it can be treated as a fixed value. When rearranged, they are expressed as Formula 111 and Formula 112.

The above formulas 111 and 112 are calculated as the following formulas 113 and 114 in consideration of the characteristics of the projection in which light emitted from the RGB three-color panel is mixed and output. In this way, low tone is calculated systematically.

The R (red) and B (blue) tristimulus values XRl, YRl, ZRl and XBm, YBm, ZBm obtained by the above-described linear interpolation are all substituted to calculate the chromaticity value of the point “n”.

  For example, when the input / output signal is 10 bits, l and m are 1024 data, and the calculated chromaticity values xo (n) and yo (n) indicating white balance are 1024 × 1024 1048576 data. . However, if the number of points n-max measured in the second step is already 1023 points, a higher resolution cannot be obtained. It is meaningful to perform linear interpolation when measuring the second step with a point smaller than the resolution of the input / output signal.

  To check how far xo (n), yo (n) obtained in this way and the chromaticity values x (n), y (n) indicating the target white balance are separated, xo (n), yo A distance Δ indicating the distance between (n) and the chromaticity values x (n) and y (n) indicating the target white balance is calculated by Formula 115.

A combination of l and m is selected such that the distance Δ obtained in the above formula 115 becomes the minimum value. Since l and m are obtained for each point “n”, when R (red) and B (blue) gamma correction values are R-Gamma (n) and B-Gamma (n), R-Gamma (n ), B-Gamma (n) is calculated by Equations 116 and 117.

As a result, R (red) and B (blue) gamma correction values are obtained.
By these calculations, R (red), G (green), and B (blue) gamma correction values R-Gamma (n), G-Gamma (n), and B-Gamma (n) are all obtained.

The gamma correction value obtained in the fifth step is stored in the gamma correction recording device unit 7.
The gamma correction value stored here is used by the video signal processing unit 4 and the gamma correction value is used as look-up table data of the output signal fo with respect to the input signal fi to the video signal control unit 4.

  As a result, the liquid crystal display device of the present invention can quickly adjust the white balance.

  That is, in the present invention, the white balance is not adjusted by feedback, and for each of R, G, and B, tristimulus values are measured for each predetermined luminance gradation, and calculation is performed by combining the measurement results. Since the white balance is adjusted by determining a combination that achieves a desired white balance for each reference luminance, the white balance can be adjusted quickly.

  Furthermore, the tristimulus values of five signals of white, red, green, blue with the maximum luminance and black with the minimum luminance are measured, and R (red), G that can be adjusted to the target white balance from the tristimulus values. The ratio of (green) and B (blue) is calculated, and the target luminance rate characteristic is changed according to the ratio. Since the white balance is adjusted according to the changed luminance rate characteristic and the target white balance, it is possible to perform a high-precision adjustment without degrading the contrast more than necessary and achieving a high gradation.

(Embodiment 2)
In the second embodiment, a method for performing the calculation of the gamma correction value for adjusting and controlling the white balance in the first embodiment more efficiently will be described.

  FIG. 5 shows a flowchart for more efficient execution of gamma correction values for white balance adjustment / control in the liquid crystal display device having the same configuration as that of the first embodiment.

  In the first step, the second step, and the third step, the same steps as in the first embodiment are performed. See Embodiment Mode 1 for details.

  By the fourth step, the tristimulus values of R (red) and B (blue) that become the target white balance for the tristimulus values of G (green) in a specific gradation “n” of G (green) are obtained. Calculate without straight line interpolation. The calculation method is described.

First, the CIE chromaticity indicating the target white balance value at the point “n” where the calculation for defining the parameter used in the calculation in the fourth step is performed is x (n) and y (n).

  In general, the relationship of Equations 118 and 119 is established between CIE chromaticity x, y and tristimulus values X, Y, Z.

The chromaticity values xo (n) and yo (n) indicating the white balance at each adjustment point “n” are expressed by Equations 120 and 121.

  Here, XRn ', YRn', ZRn 'are R (red) tristimulus values, and n' is the Point used in the second step. Similarly, XBn ″, YBn ″ and ZBn ″ are the tristimulus values of B (blue), and n ″ is the Point used in the second step.

  Since the green tristimulus value of Point “n” has already been obtained by the calculation in the third step, it can be treated as a fixed value. When rearranged, they are expressed as Formula 122 and Formula 123.

The above formulas 122 and 123 are calculated as the following formulas 124 and 125 in consideration of the characteristics of projection in which light emitted from the RGB three-color panel is mixed and output. In this way, low tone is calculated systematically.

The R (red) and B (blue) tristimulus values XRn ', YRn', ZRn 'and XBn ", YBn", ZBn "measured in the second step are all substituted into Point" Calculate the chromaticity value of n ”.

  In order to check how far xo (n) and yo (n) thus obtained are apart from the chromaticity values x (n) and y (n) indicating the target white balance, xo (n) and yo A distance Δ indicating the distance between (n) and the chromaticity values x (n) and y (n) indicating the target white balance is calculated by Expression 126.

  A combination of n ′ and n ″ is selected so that the distance Δ obtained in the above equation 126 becomes the minimum value. N ′ and n ″ are obtained for each point “n”.

  As a supplement, when the maximum value n-max, n'-max, n "-max measured in the second step is sufficiently large in the above calculation system, for example, when the input / output signal is 10 bits If the maximum values n-max, n′-max, and n ″ -max of each point are 1024, the following steps are not necessary. When the maximum value n-max, n′-max, n ″ -max of each point is 64 or the like, it is meaningful in the following steps.

  When the distance Δ obtained in the above equation 126 is larger than the specified numerical value, it is determined that the white balance calculation is insufficient.

In the fifth step, R (red) and B (blue) points n ′ and n ″ obtained in the fourth step are used as centers.
n '± p (p is a specified integer)
n ”± q (q is a specified integer)
The tristimulus values of the point are divided by linear interpolation and the resolution of the input / output signal is maximized.
The output values of the divided points are defined as l ′ and m ′. Synonymous with l and m in the first embodiment.
The chromaticity values xo (n) and yo (n) indicating the white balance are again calculated by Expression 127 and Expression 128.

  In order to check how far xo (n) and yo (n) thus obtained are apart from the chromaticity values x (n) and y (n) indicating the target white balance, xo (n) and yo The distance Δ ′ indicating the distance between (n) and the chromaticity value x (n) and y (n) indicating the target white balance is calculated by the equation 129.

A combination of l ′ and m ′ is selected such that the distance Δ ′ obtained in the above equation 29 is the minimum value. Since l 'and m' are obtained for each point “n”, R-Gamma (n) and B-Gamma (n) are used as R-Gamma (n) and R-Gamma (n). (n) and B-Gamma (n) are calculated by Equations 130 and 131.

As a result, R (red) and B (blue) gamma correction values are obtained.

  By these calculations, R (red), G (green), and B (blue) gamma correction values R-Gamma (n), G-Gamma (n), and B-Gamma (n) are all obtained. By limiting the range for linear interpolation, white balance can be calculated efficiently with the same accuracy.

The gamma correction value obtained in the sixth step is stored in the gamma correction recording device unit 7.
The gamma correction value stored here is used by the video signal processing unit 4 and the gamma correction value is used as look-up table data of the output signal fo with respect to the input signal fi to the video signal control unit 4.

  As a result, the liquid crystal display device of the present invention can quickly adjust the white balance.

  That is, in the present invention, the white balance is not adjusted by feedback, and for each of R, G, and B, tristimulus values are measured for each predetermined luminance gradation, and calculation is performed by combining the measurement results. Since the white balance is adjusted by determining a combination that achieves a desired white balance for each reference luminance, the white balance can be adjusted quickly.

  Furthermore, the tristimulus values of five signals of white, red, green, blue with the maximum luminance and black with the minimum luminance are measured, and R (red), G that can be adjusted to the target white balance from the tristimulus values. The ratio of (green) and B (blue) is calculated, and the target luminance rate characteristic is changed according to the ratio. Since the white balance is adjusted according to the changed luminance rate characteristic and the target white balance, it is possible to perform a high-precision adjustment without degrading the contrast more than necessary and achieving a high gradation.

  In both the first embodiment and the second embodiment, the tristimulus values are discretely measured by a plurality of points in the second step. The plurality of points are equally divided into n as described above to determine measurement points. However, in order to shorten the adjustment time in white balance control, n is reduced. Or, extract only the necessary points from n equally divided points, and close to a certain point, not equally. By deciding roughly near a point, it is possible to efficiently collect necessary information and use it for calculations.

  Also, instead of calculating the gamma correction value at which Δ is the minimum value after calculating Δ for all the points, for example, the calculation is performed from the low luminance side, and the gamma correction location at which Δ becomes the minimum value sequentially. By calculating, the adjustment can be performed more quickly.

(Embodiment 3)
In the third embodiment, after the calculation of the gamma correction value for adjusting and controlling the white balance in the first and second embodiments, and when the calculation result deviates more than a certain value, it is prepared in advance. By replacing it with the gamma correction value for adjustment compensation, it is possible to maintain a natural change in appearance even if the adjustment is shifted. This method is shown in the flowchart of FIG.

  In the first step, the second step, and the third step, the same steps as in the first embodiment are performed. See Embodiment Mode 1 for details.

  In the fourth step, the X stimulus value among the R (red) tristimulus values is linearly complemented, converted to the target luminance rate characteristic, and the R (red) adjustment complement gamma correction value is calculated.

  The calculation method is the same as in the third step, and the third step uses the Y stimulus value among the G (green) tristimulus values to calculate the G (green) gamma correction value. In step 4, calculation is performed using the X stimulus value among the tristimulus values of R (red).

  The obtained result is temporarily stored for later use as an R (red) adjustment complement gamma correction value.

  In the fifth step, the Z stimulus value among the B (blue) tristimulus values is linearly complemented, converted into a target luminance rate characteristic, and the B (blue) adjustment complement gamma correction value is calculated.

  The calculation method is the same as in the third step, and the third step uses the Y stimulus value among the G (green) tristimulus values to calculate the G (green) gamma correction value. In step 4, calculation is performed using the Z stimulus value among the B (blue) tristimulus values.

  The obtained result is temporarily stored as a G (blue) adjustment complement gamma correction value for later use.

  In the sixth step, R (red) and B (blue) gamma correction values R are calculated in the same manner as in the fourth step of the first embodiment or the fourth step and the fifth step of the second embodiment. -Gamma (n) and B-Gamma (n) are calculated. The minimum value of the distance value (distance Δ obtained by Formula 115 of Embodiment 1 and distance Δ ′ obtained by Formula 126 of Embodiment 2) used when obtaining the final calculation result in this step is preliminarily set. When the point “r” is larger than the preset value, and the point “r” is larger than the preset point, the R (red) gamma correction value of the point larger than the point “r” R-Gamma ( The value of n) is replaced with the R (red) adjustment complement gamma correction value obtained in the fourth step. Similarly, the B (blue) gamma correction value B-Gamma (n) of Point larger than Point “r” is replaced with the B (blue) adjustment complement gamma correction value obtained in the fifth step.

The gamma correction value obtained in the seventh step is stored in the gamma correction recording device unit 7.
The gamma correction value stored here is used by the video signal processing unit 4 and the gamma correction value is used as the look-up table data of the output signal fo with respect to the input signal fi to the video signal control unit 4. The video display device naturally changes the white balance up to the maximum brightness of the device even if the target brightness rate characteristics do not match the characteristics of the LCD panel and the white balance deviates from the target value. You can get a white balance that doesn't give you a sense of incompatibility.

(Embodiment 4)
According to the control method of the present invention, it is possible to arbitrarily set whether the white balance is adjusted accurately to a certain level of the input signal. That is, in view of the target luminance rate characteristic, it is possible to arbitrarily determine how much of the white balance is accurately adjusted with respect to the maximum luminance of the apparatus.

Describe how.
In the apparatus and method of the first embodiment, arbitrarily determine how much brightness the white balance is adjusted to, and determine the%, where the value is defined as a decimal number Q To do.

  In the first step, tristimulus values are measured in the same manner as in the first embodiment. In the second step, the ratios D and E are calculated as in the first embodiment.

  If either D or E calculated in the second step in the third step is greater than or equal to 1 / Q, D and E are compared, and the default target luminance rate characteristic is a large value. And then divide by Q.

  If the resulting luminance rate characteristic is "adjustment luminance rate characteristic"

It becomes.

Specifically, when performing accurate white balance adjustment from 0% to 90% of the maximum brightness of the apparatus, Q = 0.9, and the adjusted brightness rate characteristic is obtained by multiplying the target brightness rate characteristic by D or E and Q. It is obtained by dividing by things.
In other words, up to 90% of the maximum luminance can be displayed with the white balance as a target, and from 90% to 100%, an apparatus having a video mode in which luminance is prioritized can be realized.

  By this method, it is possible to arbitrarily set whether white balance is adjusted accurately to a certain level of the input signal. In view of the target luminance rate characteristic, it is possible to arbitrarily determine what percentage of brightness to accurately adjust the white balance with respect to the maximum brightness of the apparatus.

  As described above, the present invention provides a video display unit that displays and displays a video signal, a video signal control unit that generates a video signal used for white balance control, and outputs an input video signal output to the video display unit, Outputs the output video signal projected on the screen as tristimulus values or outputs a light output detector that outputs data that can be converted to tristimulus values, and detects tristimulus values or light output obtained from the light output detector Using the data obtained by converting the data obtained from the tristimulus value to the tristimulus value, the ratio of R (red), G (green), and B (blue) when adjusted to the target white balance is calculated, and the target luminance rate The white balance control unit that changes the characteristics and adjusts the white balance according to the luminance ratio characteristic for adjustment, and the gamma correction values of R (red), G (green), and B (blue) generated by the white balance control unit Record Since the gamma correction value recording device unit and the target value recording device unit for recording the target white balance and the target luminance rate characteristic are configured, the white balance can be adjusted quickly. It is.

  That is, in the present invention, the white balance is not adjusted by feedback, and for each of R, G, and B, tristimulus values are measured for each predetermined luminance gradation, and calculation is performed by combining the measurement results. Since the white balance is adjusted by determining a combination that achieves a desired white balance for each reference luminance, the white balance of a liquid crystal display device such as a liquid crystal television can be adjusted quickly.

  Furthermore, the tristimulus values of five signals of white, red, green, blue with the maximum luminance and black with the minimum luminance are measured, and R (red), G that can be adjusted to the target white balance from the tristimulus values. The ratio of (green) and B (blue) is calculated, and the target luminance rate characteristic is changed according to the ratio. Since the white balance is adjusted according to the changed luminance rate characteristic and the target white balance, it is possible to perform a high-precision adjustment without degrading the contrast more than necessary and achieving a high gradation.

  Therefore, it is highly expected to be applied to a liquid crystal display device that requires white balance accuracy and adjustment speed.

Configuration diagram of liquid crystal display device of the present invention Configuration diagram of liquid crystal display device of the present invention Flowchart of white balance control method of the present invention Flowchart of white balance control method of the present invention Flowchart of white balance control method of the present invention Flowchart of white balance correction method of the present invention

DESCRIPTION OF SYMBOLS 1 Light source 2 Image | video conversion part 3 Screen 4 Image | video signal control part 5 Light output detection part 6 White balance control part 7 Gamma correction value memory | storage part 8 Target value memory | storage part 20 Image | video display part

Claims (4)

A video display unit for displaying and displaying a video signal;
A video signal control unit that generates a video signal used for white balance control and outputs an input video signal to be output to the video display unit;
An output video signal projected on the screen as a tristimulus value, or a light output detector that outputs data that can be converted to a tristimulus value;
Using the tristimulus values obtained from this light output detection unit or the data obtained by converting the data obtained from the light output detection unit into tristimulus values, R (red), G ( A white balance control unit that calculates a ratio of green) and B (blue), changes a target luminance rate characteristic, and adjusts the white balance according to the adjustment luminance rate characteristic;
A gamma correction value recording unit that records the gamma correction values of R (red), G (green), and B (blue) generated by the white balance control unit;
A target value recording device section for recording the target white balance and the target luminance rate characteristic;
A liquid crystal display device comprising: The video display unit
A light source;
A video conversion unit that synthesizes the illumination light from this light source and the input video signal and converts them into video information;
The liquid crystal display device according to claim 1, comprising a screen on which an output signal from the image conversion unit is projected. A first step of measuring tristimulus values of a predetermined signal;
A second step of calculating a ratio of R (red), G (green), and B (blue) that can be adjusted to the target white balance from the tristimulus values;
A third step of changing the target luminance rate characteristic so as to normalize the luminances of R (red), G (green), and B (blue) according to the ratio;
According to the fourth step of adjusting the white balance in accordance with the changed luminance rate characteristic and the target white balance,
A white balance control method that determines the gamma correction value. 4. The white balance according to claim 3, wherein in the third step, the target luminance rate characteristic is changed so as to normalize the luminances of R (red), G (green), and B (blue) with respect to a predetermined ratio. Control method.

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