JP2010128072A - Backlight driving device and backlight driving control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the degree of freedom of luminescent colors while sufficiently reducing power consumption. <P>SOLUTION: A primary color light source selecting section 3-1 selects a white color light source and maximum two primary color light sources out of three primary color light sources. A computing section 3-2 computes the output of the three selected light sources so that emission luminance chromaticity is a target value. A PWM (pulse width modulation) generating part 3-3 generates output signals to the white light source and the selected maximum two primary color light sources according to a control signal, and supplies them to a driving part 3-4. The driving part 3-4 lights the corresponding white color light source 4-1 and the selected primary color light sources 4-i by a white color light source driving part 3-4-1 corresponding to the white color light source 4-1 and by a driving part 3-4-i corresponding to the selected maximum two primary color light sources, that is, the driving part 3-4 puts out the primary color light source 4-j which was not selected, and replaces it with the emission of the white color light source 4-1. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a backlight driving device and a backlight driving control method.

  A backlight in a display device using a liquid crystal display is required to have a high luminance and low power consumption and to be able to freely set a light emission color such as reddish white or bluish white. Conventionally, a backlight using a white light source such as CCFL (cold cathode fluorescent lamp) or white LED (light emitting diode) or a primary color light source such as R / G / B (RED, GREEN, BLUE) is combined. There is something.

  However, a backlight using a white light source such as a CCFL or a white LED easily achieves high luminance and low power consumption, but has a problem that the emission color is unique and cannot be changed.

  Further, a backlight combining primary color light sources such as R / G / B can freely set the emission color by changing the mixing ratio of each color as shown in FIG. In addition, since the luminous efficiency is lower than that of a white light source, there is a problem that it is difficult to realize high luminance and low power consumption.

Therefore, a backlight having four primary colors has been proposed by combining a white light source and a three primary color light source to control the light emission distribution between the primary color light source and the white light source as shown in FIG. Reference 1). Ordinary optical sensors have three primary colors, and simultaneous emission of the four primary colors is difficult to control the light emission balance, and there is a problem that the light emission color is unstable. Realizes simultaneous emission of primary colors.
JP 2007-141738 A

  However, in the above-described conventional technology, although the degree of freedom of the emission color is increased, there is a problem that the power consumption cannot be sufficiently reduced because simultaneous emission of the four primary colors is performed as shown in FIG.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a backlight drive device and a backlight drive capable of improving the degree of freedom of emission color while sufficiently reducing power consumption. It is to provide a control method.

  In order to solve the above-described problem, the present invention is a backlight driving device that controls driving of a white light source and a plurality of primary color light sources, and the plurality of primary color light sources are turned on according to a target color. And a drive control means for driving the white primary light source and the lighting primary color light source selected by the selection means to light according to the target color.

  According to the present invention, in the above invention, the drive control means turns off the primary color light sources not selected by the selection means.

  The present invention is characterized in that, in the above-mentioned invention, the selection means switches a light source for a primary color to be selected according to a target color.

  The present invention is characterized in that, in the above invention, the selecting means replaces one or more primary color light sources with a white light source and selects a lighting primary color light source from the plurality of primary color light sources.

  The present invention is characterized in that, in the above invention, the selecting means selects at least one primary color light source or two primary color light sources.

The present invention is characterized in that, in the above invention, the selecting means selects a lighting primary color light source from the plurality of primary color light sources so that the luminance of the white light source is maximized.
The present invention is characterized in that, in the above invention, the selecting means selects a lighting primary color light source from the plurality of primary color light sources so that power consumption or heat generation is minimized. As a means for simply evaluating the power consumption, for example, a primary color light source is selected so that the luminance of the white light source is maximized.

  Further, in order to solve the above-described problem, the present invention is a backlight drive control method for driving and controlling a white light source and a plurality of primary color light sources, and includes a plurality of primary color light sources according to a target color. A backlight drive control method comprising: selecting a lighting primary color light source; and driving the white light source and the selected lighting primary color light source to light according to the target color.

  According to the present invention, a lighting primary color light source is selected from a plurality of primary color light sources according to the target color, and the white light source and the selected lighting primary color light source are driven to light according to the target color. Therefore, it is possible to reduce power consumption while maintaining the designated emission color.

  Further, according to the present invention, the primary color light sources not selected are turned off. Therefore, power consumption can be reduced.

  According to the present invention, the lighting primary color light source to be selected is switched according to the target color. Therefore, the designated emission color can be maintained.

  According to the present invention, the primary color light source of one or more colors is replaced with a white light source, and a lighting primary color light source is selected from a plurality of primary color light sources. Therefore, it is possible to reduce power consumption while maintaining the designated emission color.

  Further, according to the present invention, at least one primary color light source or two primary color light sources are selected. Therefore, the designated emission color can be maintained.

  In addition, according to the present invention, a lighting primary color light source is selected from a plurality of primary color light sources so that the luminance of the white light source is maximized. Therefore, it is possible to reduce power consumption while maintaining the designated emission color.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram illustrating a configuration of a backlight driving device according to an embodiment of the present invention. In the figure, the backlight drive device 2 according to the present embodiment is mounted in a display device such as a display in combination with the designation unit 1, for example. The designation unit 1 is, for example, a button that accepts data input indicating luminance and chromaticity designated by the user, and a push-down switch can be applied. The designation unit 1 may output an instruction to increase or decrease the luminance or chromaticity value to the calculation unit 3-2, or output the luminance or chromaticity value itself to the calculation unit 3-2. You may do it.
The backlight driving device 2 includes a backlight control unit 3 and a backlight 4. The backlight control unit 3 includes a primary color light source selection unit 3-1, a calculation unit 3-2, a PWM (pulse width modulation) generation unit 3-3, and a drive unit 3-4.

  When the luminance and chromaticity are designated by the designation unit 1, the primary color light source selection unit 3-1 selects a white light source and a maximum of two primary color light sources from the three primary color light sources. Which primary color light source is selected is not fixed, but is switched according to the target color (chromaticity). Alternatively, the primary color light source that should emit light may be selected so that the luminance of the white light source is maximized. The calculation unit 3-2 determines the drive output of the selected white light source and the maximum two primary color light sources according to the target color (luminance / chromaticity) specified by the specifying unit 1. At this time, the calculation unit 3-2 determines the drive output of the selected white light source and the maximum two primary color light sources so that the power consumption is minimized while maintaining the target color. The PWM generation unit 3-3 outputs a pulse width modulated output for controlling the operation of each driving unit 3-4 for driving the backlight as each light source in accordance with the driving output determined by the calculating unit 3-2. Generate a signal.

  The driving unit 3-4 includes a white light source and a white light source driving unit 3-4-1, a red light source driving unit 3-4-2, and a green light source driving unit 3-4-3 prepared for each color light source. And a blue light source driving unit 3-4-4. The drive unit 3-4 drives and controls the backlight 4, which is each light source, according to an output signal from the PWM generation unit 3-3. The backlight 4 includes a white light source 4-1, a red light source 4-2, a green light source 4-3, and a blue light source 4-4 as primary color light sources, and emits light according to a drive signal from the drive unit 3-4. The white light source 4-1, the red light source 4-2, the green light source 4-3, and the blue light source 4-4 are preferably arranged closely.

Next, the operation of this embodiment will be described.
In the configuration described above, when the luminance and the emission color are designated by the designation unit 1, the primary color light source selection unit 3-1 minimizes the power consumption of the white light source and the maximum of two primary color light sources from the three primary color light sources. Select Thereafter, the calculation unit 3-2 calculates the outputs of the selected three light sources so that the emission luminance chromaticity becomes a target value, and supplies a control signal corresponding to the calculation result to the PWM generation unit 3-3. The PWM generation unit 3-3 generates an output signal for the white light source and the selected maximum two primary color light sources in accordance with the control signal, and supplies the output signal to the drive unit 3-4.

  In the driving unit 3-4, a white light source driving unit 3-4-1 corresponding to the white light source 4-1 and a driving unit 3-4-i (i = 2, 3, 4), the corresponding white light source 4-1 and the primary color light source 4-i (i = 2, any of two) are turned on. That is, even if three or more primary color light sources are arranged, it is the maximum of two primary colors that emit light simultaneously. The remaining primary color light source 4-j (any one of j = 2, 3, and 4 which is not selected) is turned off and replaced with the light emission of the white light source 4-1.

2 and 3 are conceptual diagrams (xy chromaticity diagrams) for explaining the backlight control method according to the present embodiment. When the luminance and the emission color are designated for the backlight having the color gamut of FIG. 2, as shown in FIG. 3, the green light source 4-3, the blue light source 4-4, and the white light source 4 other than the red light source 4-2. -1 is selected, and the light emission distribution is calculated so that the light emission luminance chromaticity becomes the target value for the outputs of the three selected light sources. That is, since the emission color of the white light source includes a red component, a green component, and a blue component, by using a white light source instead of any one of the primary color light sources, it is included in the emission color of the white light source. In consideration of the red component, the green component, and the blue component, the light emission amount of the primary color light source to be emitted may be controlled.
In the case of FIG. 2, the primary color light source selection unit 3-1 includes a white light source that surrounds the target chromaticity on the chromaticity diagram such as CIE1931xy among the set values of luminance and chromaticity designated by the designation unit Then, a maximum of two primary color light sources are selected (FIG. 3). When there are four or more primary color light sources mounted on the backlight, there are a plurality of combinations of white + two primary color light sources that realize the target color. For this reason, the power consumption (or heat generation) of each combination is calculated, and the smallest combination is selected. For example, FIG. 4 is a conceptual diagram showing an example in which a target color is realized by a backlight having four primary color light sources. Here, any of the following two combinations can realize the target color.
(A) Combination 1 = (white light source, primary color light source c, primary color light source d) (FIG. 5)
(A) Combination 2 = (white light source, primary color light source b, primary color light source d) (FIG. 6)
Therefore, the power consumption of each combination is calculated, and the minimum combination is selected. In the combination 1, the primary color light source a and the primary color light source b are turned off. In the combination 2, the primary color light source a and the primary color light source c are turned off.
Here, the calculation formula of power consumption is not one, and the following means can be considered.
(C) Calculation example 1 Select the combination that minimizes the sum of the luminance of each light source divided by the luminous efficiency. (D) Calculation example 2 Select the combination that maximizes the luminance of the white light source. The drive output is determined using the set value calculated in this way.

  FIG. 7 is a schematic block diagram showing the configuration of a display device (liquid crystal display) using the present invention. In this embodiment, a light emitting light source is selected according to the target BL color and priority conditions (such as display color gamut width or low power consumption), and only the selected light source emits light and is adjusted by adjusting the video display unit. Keep the way you look. As an object of color correction of an image, for example, when the red primary color light source is turned off, the display color gamut is calculated to compensate for the weakening red. It is also conceivable that the target BL color is automatically adjusted by analyzing the color distribution of the input video as well as the user's instruction.

  In this figure, a priority condition instructing unit 10 receives data input representing a priority condition from a user. This priority condition instruction is, for example, an instruction to specify either the display color gamut width or low power consumption. Here, the low power consumption priority state may be referred to as high luminance priority. This is because when the power consumption is constant, the light emission luminance can be improved in this state as compared with the color gamut priority.

The backlight drive unit 20 is driven based on the input (priority condition) received from the priority condition instruction unit 10 and the input received from the white point instruction unit 30 or the instruction output from the video circuit unit 40. The light source of the color to be lit 60 is selected, and the display color gamut to be displayed on the video display unit 70 is calculated.
In the backlight drive unit 20, the target BL color determination unit 21 has a function of receiving an instruction of a target backlight color that designates a target backlight color, and an image output from the color distribution measurement unit 41 of the video circuit unit 40. And a function of receiving color distribution information. The target BL color determination unit 21 also turns on the backlight based on an instruction output from the color distribution measurement unit 41 based on the video signal of the external video device 50 or an input received by the white point instruction unit 30. The target BL color (e.g., tristimulus values specified by XYZ), which is the color of, is determined and output to the light source combination calculator 23.

The light source chromaticity storage unit 22 stores in advance the chromaticity (for example, tristimulus values specified by XYZ) of each color light source that the BL light source 60 can emit.
The light source combination calculation unit 23 refers to the information stored in the light source chromaticity storage unit 22 and is determined by the target BL determination unit 21 based on the chromaticity of each light source (for example, FIG. 2 or FIG. 4). The light source combination group that realizes the color of the light source is calculated. If there are a plurality of light source combination groups, they are calculated and output to the power calculation unit 25 and the color gamut calculation unit 24, respectively. The light source combination group is a maximum of three colors, for example, an area including the target backlight color in FIGS. 3, 5, and 6, and an area surrounded by a white light source and one or two primary color light sources. (Triangle or line segment) group.

Based on the calculation result of the light source combination calculation unit 23, the color gamut calculation unit 24 calculates a display color gamut when the unselected primary color light sources are turned off for each combination of light sources to emit light.
The power calculator 25 calculates the power calculated by the light source combination calculator 23 when the light source is turned on for each light source combination. This calculation is based on the following formula (1). This calculation is performed for each combination of light sources.
Power = Luminance brightness / Luminous efficiency (1)

  The light source determination unit 26 uses the light source (light emission to be emitted) based on either the power calculation unit 25 or the color gamut calculation unit 24 according to the priority condition input from the priority condition instruction unit 10. Select (Light source). Here, the selection is made in accordance with an instruction to prioritize whether the light source of the backlight is turned on so as to reduce power consumption or the backlight is turned on so as to have a wide color gamut. When an instruction to prioritize low power consumption is input, a combination of primary color light sources with the lowest power consumption is selected from the calculation results of the power calculation unit 25. On the other hand, when an instruction to prioritize the wide color gamut is input, a combination of primary color light sources when the display color gamut is the widest is selected based on the calculation result of the color gamut calculation unit 24.

  The light source driving unit 27 drives and controls backlights that are light sources (white light source, primary color light source a, primary color light source b, primary color light source c,...) According to an output signal from the use light source determination unit 26. Here, an output signal for driving the BL light source 60 is generated.

  The white point instructing unit 30 is, for example, a button that accepts data input indicating luminance and chromaticity designated by the user, and a push-down switch can be applied. For example, the white point instruction unit 30 may output an instruction to increase or decrease the luminance or chromaticity value to the target BL color determining unit 21, or the luminance or chromaticity value itself may be output as the target BL color. You may make it output to the determination part 21. FIG.

The video circuit unit 40 drives the video display unit 70 in accordance with a signal from the external video device 50.
Next, in the video circuit 40, the color distribution measurement unit 41 analyzes the color distribution of the output image and outputs the analysis result to the target BL color determination unit 21 as color distribution information. The video correction unit 42 corrects the color displayed on the video display unit 70 by correcting the color of the primary color light source to be turned off based on the calculation result of the color gamut calculation unit 24 and the color displayed on the screen. To do. For example, when the light source determination unit 26 determines to turn off the red primary color light source and turn on the backlight as the light source of the backlight, the correction is performed based on this determination. The calculation result of the display color gamut when the light is turned off is referred to from the calculation result of the color gamut calculation unit 24, and correction is made to compensate for the weak red color to become the target color gamut.

The external video device 50 outputs a video signal to be displayed on the video display unit 70 to the video circuit unit 40.
The BL light source 60 is a backlight device composed of a white light source and a plurality of primary color light sources. Examples of primary color light sources include R (red), G (green), and B (blue).
The video display unit 70 is a liquid crystal panel, and displays video from the external video device 50 based on the video signal from the video circuit unit 40.

  According to the embodiment described above, since one or more primary color light sources are replaced with white light sources to emit light, the following effects can be obtained.

(1) Since the primary color light source with low luminous efficiency is replaced with a white light source, the power consumption can be minimized while maintaining the designated luminance chromaticity. On the contrary, when the chromaticity and the power consumption are made equal, the light emission luminance can be improved.

(2) Since three or more primary color light sources are mounted, the emission color can be selected in a wider range than the conventional method in which one or two primary color light sources are added to the white light source.

(3) Simultaneous emission colors are three colors at the maximum. For this reason, the output value of each required light source can be uniquely determined with respect to the target color designated by the tristimulus value which is human visibility. In addition, even a general three-primary-color optical sensor can stably control a multi-primary light source.

(4) The degree of freedom in selecting the primary color light source can be improved. Since a maximum of two colors corresponding to the target color are turned on simultaneously, the color control does not become unstable even if the number of primary color light sources is increased.

  In addition, the backlight drive device by embodiment mentioned above can be utilized not only for a liquid crystal display but for a Schaukasten or a projector.

It is a block diagram which shows the structure of the backlight drive device by embodiment of this invention. It is a conceptual diagram for demonstrating the backlight control method by this embodiment. It is a conceptual diagram for demonstrating the backlight control method by this embodiment. It is a conceptual diagram for demonstrating the backlight control method by this embodiment. It is a conceptual diagram for demonstrating the backlight control method by this embodiment. It is a conceptual diagram for demonstrating the backlight control method by this embodiment. It is an operation example of the liquid crystal display in this embodiment. It is a conceptual diagram for demonstrating the backlight control method by a prior art.

Explanation of symbols

2 Backlight Drive Unit 3 Backlight Control Unit 3-1 Primary Color Light Source Selection Unit 3-2 Calculation Unit 3-3 PWM Generation Unit 3-4 Drive Unit 3-4-1 White Light Source Drive Unit 3-4-2 Red Light Source Drive 3-4-3 Green light source driving unit 3-4-4 Blue light source driving unit 4 Backlight 4-1 White light source 4-2 Red light source 4-3 Green light source 4-4 Blue light source

Claims (8)

A backlight driving device for controlling lighting of a white light source and a plurality of primary color light sources,
A selection means for selecting a lighting primary color light source from the plurality of primary color light sources according to a target color;
A backlight driving apparatus comprising: a drive control unit configured to drive the white light source and the lighting primary color light source selected by the selection unit according to the target color.   2. The backlight driving apparatus according to claim 1, wherein the drive control means turns off the primary color light sources not selected by the selection means.   2. The backlight driving apparatus according to claim 1, wherein the selection unit switches a light source for a primary color to be selected in accordance with a target color.   The backlight driving apparatus according to claim 1, wherein the selection unit replaces one or more primary color light sources with a white light source and selects a lighting primary color light source from the plurality of primary color light sources.   The backlight driving apparatus according to claim 1, wherein the selection unit selects at least one primary color light source.   2. The backlight driving apparatus according to claim 1, wherein the selection unit selects a lighting primary color light source from the plurality of primary color light sources so that the luminance of the white light source is maximized.   2. The backlight driving apparatus according to claim 1, wherein the selection unit selects a lighting primary color light source from the plurality of primary color light sources so that power consumption or heat generation is minimized. A backlight drive control method for lighting and controlling a white light source and a plurality of primary color light sources,
Selecting a lighting primary color light source from the plurality of primary color light sources according to a target color;
A backlight driving control method, comprising: lighting the white light source and the selected lighting primary color light source according to the target color.

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