JP6334158B2 - Display device and display device control method - Google Patents

Description

  The present invention relates to a display device and a display device control method.

  The liquid crystal display device in the prior art includes an RGB color filter substrate, a liquid crystal layer, a backlight device, and the like. The backlight device of such a liquid crystal display device is proposed to improve the color reproduction range of the liquid crystal display device by mixing light from light sources such as red, green, blue, and purple to emit white light. Has been.

  In these multi-color backlight devices, white balance adjustment for displaying a designated white point designated by a user with Yxy or XYZ values is performed by changing the luminance of the backlight of each color (for example, patents). Reference 1).

JP-A-5-127620

  However, since it is difficult to determine the driving value of the backlight for displaying the designated white point, it is generally necessary to incorporate a color sensor in the backlight device and feedback-control the detection value of the color sensor. Alternatively, it is necessary to attach an external color sensor to the backlight device and feedback-control the detection value of the color sensor. These color sensors are expensive, and when they are externally attached, the liquid crystal panels that can be attached are limited.

  Also, when calibrating white balance using a color sensor, it takes a lot of time to adjust many white spots, the range of white spots that can be set is limited, or when white spots are changed Recalibration was necessary.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a display device and a display device control method capable of easily performing white balance calibration.

  In order to achieve the above object, a display device according to the present invention includes a backlight, a display unit that displays an image, and an image displayed on the display unit when the backlight emits light in a first color. A first measurement value that is a color measurement value, and a second measurement value that is a color measurement value of an image displayed on the display unit when the backlight emits light in a second color. The first measurement value is converted into a measured luminance value that is a value of the color space based on the backlight, using a storage unit that stores the color space conversion coefficient obtained using the second measurement value. Using a backlight luminance calculation unit and the color space conversion coefficient, a target white point setting value indicated by a value in the same color space as the color space of the first measurement value is converted into a target luminance value of the backlight. The target brightness calculation unit and the measured brightness value. Comprising a drive value converter for converting the values into drive values for the backlight, the.

  In order to achieve the above object, a display device control method according to the present invention is a measurement value of a color of an image displayed on a display unit that displays an image when a backlight emits light in a first color. A storage procedure for storing a measurement value of 1 and a second measurement value that is a measurement value of a color of an image displayed on the display unit when the backlight is caused to emit light in a second color; A backlight luminance calculation procedure for converting the first measurement value into a measurement luminance value that is a value of the color space based on the backlight, using a color space conversion coefficient obtained using the second measurement value; Using the color space conversion coefficient obtained by the backlight luminance calculation procedure, a target white point setting value indicated by a value in the same color space as the color space of the first measurement value is obtained as the target luminance of the backlight. A target luminance calculation procedure for converting to a value, and the eye Using the measured luminance value converted by the luminance calculation procedure, including, a drive value conversion procedure for converting the driving value for said backlight the target luminance value.

  According to the present invention, white balance calibration can be easily performed.

1 is a block diagram of a schematic configuration of a display device according to a first embodiment. It is a figure explaining the relationship between the wavelength of BL, and light quantity when the drive value which concerns on 1st Embodiment is changed. It is a figure explaining the relationship of the light quantity of BL when the drive value which concerns on 1st Embodiment is changed. It is a block diagram of a schematic structure of a BL drive control unit according to the first embodiment. It is a flowchart of the process sequence which the backlight drive device which concerns on 1st Embodiment performs. It is a block diagram of schematic structure of the display device concerning a 2nd embodiment. It is sectional drawing of the light source used for the backlight which concerns on 2nd Embodiment. It is a block diagram of schematic structure of a BL drive control part concerning a 2nd embodiment. It is a flowchart of the process sequence which the backlight drive device which concerns on 2nd Embodiment performs.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram of a schematic configuration of a display device 1 according to the present embodiment. As shown in FIG. 1, the display device 1 includes a backlight device 2 and a display unit 4. A video output device 3 and a display unit 4 are connected to the backlight device 2. In addition, the color sensor 5 is installed on the display unit 4 only during calibration.

The color sensor 5 measures the display color on the display unit 4 and outputs an XYZ value as a result of the measurement to a BL (Back Light) drive control unit 20. The color sensor 5 is, for example, a sensor configured with the same sensitivity as that of the human eye or a sensor that measures a spectral wavelength component.
The video output device 3 outputs a video signal to the backlight device 2. The video output device 3 is, for example, a PC (personal computer), a portable terminal, or the like.

  The display unit 4 is a liquid crystal panel, for example. The display element mounted on the display unit 4 is a display element other than a liquid crystal type, for example, an organic electroluminescence display element, an inorganic electroluminescence display element, a PALC (Plasma Address Liquid Crystal), a PDP (Plasma Display Panel). Or FED (Field Emission Display).

The backlight device 2 includes a target white point storage unit 10, a BL drive control unit 20, an R-BL drive circuit 30, a G-BL drive circuit 40, a B-BL drive circuit 50, and three primary colors BL60.
As shown in FIG. 1, the backlight device 2 of the present embodiment has red (R; for example, second color), green (G; for example, third color), and blue (B: for example, fourth color). Mixed to emit white (for example, fourth color) light.

  The target white point storage unit 10 stores, for example, setting values for R-BL61, G-BL62, and B-BL63 when white light emission is set in advance by the user of the backlight device 2. For example, when the backlight device 2 of the present embodiment is applied to a liquid crystal display device, the set value is that of the R-BL61, G-BL62, and B-BL63 while the user looks at the display on the display unit 4. The brightness is adjusted so that the user feels that white light is emitted, and is a value set by an operation unit (not shown).

  The BL drive control unit 20 is controlled so that the BL drive value becomes a wavelength near red, near green, near blue, and near white while the white video signal is displayed on the display unit 4 at the time of calibration. The color sensor 5 to which the display unit 4 is attached receives the measurement result.

The BL drive control unit 20 alternates between RGB luminance and XYZ values, which are the color space of the backlight, based on the XYZ values (primary color calibration point data) measured by the color sensor 5 during BL drive near each color when white balance is set. A color space conversion coefficient to be converted into is generated by a known technique. This color space conversion coefficient is represented by an inner product of 3 rows and 3 columns. In addition, the BL drive control unit 20 converts the XYZ values (white calibration point data) measured by the color sensor 5 when white balance is set and the BL drive near white into RGB luminance using the created color space conversion coefficient. . Then, the BL drive control unit 20 creates a luminance-drive value conversion LUT (LookUp Table; Lookup Table) from the converted RGB luminance when white balance is set. Then, the BL drive control unit 20 converts the target white point of the XYZ value into the target luminance of RGB that is the backlight color space, using the created color space conversion coefficient. Then, the BL drive control unit 20 outputs the converted target luminance values of RGB to the R-BL drive circuit 30, the G-BL drive circuit 40, and the B-BL drive circuit 50.
The configuration of the BL drive control unit 20 will be described later.

The R-BL drive circuit 30 drives the R-BL 61 of the three primary colors BL60 based on the drive signal output from the BL drive control unit 20.
The G-BL drive circuit 40 drives the G-BL 62 of the three primary colors BL60 based on the drive signal output from the BL drive control unit 20.
The B-BL drive circuit 50 drives the B-BL 63 of the three primary colors BL60 based on the drive signal output from the BL drive control unit 20. The output signals of the R-BL drive circuit 30, the G-BL drive circuit 40, and the B-BL drive circuit 50 are PWM (Pulse Width Modulation) type signals (hereinafter referred to as PWM signals).

The three primary colors BL60 include R-BL61, G-BL62, and B-BL63.
The R-BL 61 is a light source that emits red light in response to a drive signal output from the R-BL drive circuit 30. The center wavelength of red light is about 660 [nm], for example.
The G-BL 62 is a light source that emits green light in response to a drive signal output from the G-BL drive circuit 40. The center wavelength of green light is, for example, about 540 [nm].
The B-BL 63 is a light source that emits blue light in response to a drive signal output from the B-BL drive circuit 50. The center wavelength of blue light is, for example, about 460 [nm].
R-BL61, G-BL62, and B-BL63 are a light emitting diode (LED; Light Emitting Diode) or a semiconductor laser, for example.

FIG. 2 is a diagram for explaining the relationship between the wavelength of BL and the amount of light when the drive value according to the present embodiment is changed. In FIG. 2, the horizontal axis represents wavelength and the vertical axis represents light quantity.
In FIG. 2, the waveform indicated by reference sign g1 is the waveform of B-BL63, the waveform indicated by reference sign g2 is the waveform of G-BL62, and the waveform indicated by reference sign g3 is the waveform of R-BL61. The waveforms indicated by reference signs g4 and g5 are waveforms when the drive value of B-BL63 is lowered from the state of the waveform indicated by reference numeral g1 to the duty of the PWM signal that is the drive signal. That is, the duty of the waveform of the code g2 is lower than the duty of the waveform of the code g1, and the duty of the waveform of the code g3 is lower than the duty of the waveform of the code g2. When the light source of the backlight is an RGB three-color LED, as shown in FIG. 2, even if the drive value is changed, the wavelength of the light quantity does not change, and only the light quantity changes. FIG. 2 shows an example of only B-BL63, but similarly for R-BL61 and B-BL62, even if the drive value is changed, the wavelength of the light intensity does not change, and only the light intensity changes. To do. Since the peak value of the light amount does not change in this way, it indicates that the color coordinate does not change.

FIG. 3 is a diagram for explaining the relationship between the amount of light of BL when the drive value according to the present embodiment is changed. In FIG. 3, the horizontal axis represents the drive value, and the vertical axis represents the amount of light.
In FIG. 3, the straight line indicated by reference sign g11 indicates the relationship between the drive values of R-BL61, G-BL62, and B-BL63 and the amount of light. Like the straight line indicated by reference sign g11, the amount of light is almost directly proportional to the drive value.

Next, the BL drive control unit 20 will be described.
FIG. 4 is a block diagram of a schematic configuration of the BL drive control unit 20 according to the present embodiment. 4, the BL drive control unit 20 includes a BL characteristic storage unit 201, a BL luminance calculation unit 202, a target luminance calculation unit 203, an R luminance-driving value conversion coefficient 207, a G luminance-driving value conversion coefficient 208, A B luminance-drive value conversion coefficient 209 and a drive value limiting unit 210 are provided.

The BL characteristic storage unit 201 includes a primary color calibration point storage unit 2011 and a white calibration point storage unit 2012.
In the primary color calibration point storage unit 2011, a white video signal is displayed on the display unit 4 at the time of calibration, and the color sensor 5 is displayed when the BL drive values are set near red, green, and blue. The output XYZ values are stored.
The white calibration point storage unit 2012 displays an XYZ value output from the color sensor 5 when a white video signal is displayed on the display unit 4 and the BL drive value is set near white during calibration. .

  Based on the primary color calibration point data stored in the primary color calibration point storage unit 2011, the BL luminance calculation unit 202 uses a well-known color space conversion coefficient for alternately converting RGB luminance and XYZ values, which are the color space of the backlight. Seeking by technology. The BL luminance calculation unit 202 stores the obtained color space conversion coefficient in, for example, the primary color calibration point storage unit 2011. The BL luminance calculation unit 202 converts the white calibration point data stored in the white calibration point storage unit 2012 into RGB luminance using the obtained color space conversion coefficient. The BL luminance calculation unit 202 creates a luminance-driving value conversion LUT that is an RGB independent 1D_LUT (one-dimensional lookup table) from the converted RGB luminance. The created R luminance-driving value conversion LUT 207 to B luminance-driving value conversion LUT 209 show characteristics complemented with white point calibration data. As described with reference to FIG. 3, since the luminance is almost directly proportional to the driving value, the LUT is almost a straight line. For this reason, in this embodiment, the white calibration point may be about 1 to 2 points, and the calibration can be easily performed.

  The target luminance calculation unit 203 uses the color space conversion coefficient created by the BL luminance calculation unit 202 to convert the target white point (XYZ value) stored in the target white point storage unit 10 into the backlight color space. Conversion to RGB luminance target values. Next, the target luminance calculation unit 203 outputs each of the converted RGB luminance target values to the R luminance-drive value conversion unit 207 to the B luminance-drive value conversion unit 209.

  The R luminance-driving value conversion unit 207 stores the R luminance-driving value conversion LUT created by the BL luminance calculating unit 202. Further, the R luminance-driving value conversion unit 207 inputs the R luminance target value 204 output from the target luminance calculating unit 203 to the stored R luminance-driving value conversion LUT, and R backlight for the R-BL 61. The drive value is converted, and the converted R backlight drive value is output to the R-BL drive circuit 30.

  The G luminance / driving value conversion unit 208 stores the G luminance / driving value conversion LUT created by the BL luminance calculation unit 202. Further, the G luminance-driving value conversion unit 208 inputs the G luminance target value 205 output from the target luminance calculation unit 203 to the stored G luminance-driving value conversion LUT, so that the G backlight for the G-BL 62 is obtained. The converted value is converted into a drive value, and the converted G backlight drive value is output to the G-BL drive circuit 40.

  The B luminance-driving value conversion unit 209 stores the B luminance-driving value conversion LUT created by the BL luminance calculating unit 202. Further, the B luminance-driving value conversion unit 209 inputs the B luminance target value 206 output from the target luminance calculation unit 203 to the stored B luminance-driving value conversion LUT, and performs a B backlight for the B-BL 63. The drive value is converted, and the converted B backlight drive value is output to the B-BL drive circuit 50.

The backlight driving value converted by the R luminance-driving value conversion unit 207 to the B luminance-driving value conversion unit 209 is input to the driving value limiting unit 210. Next, the drive value limiting unit 210 determines whether or not the input backlight drive value is less than a predetermined maximum value. When the input backlight driving value is equal to or greater than a predetermined maximum value, the driving value limiting unit 210 limits other backlight driving values according to the backlight driving value exceeding the maximum value. To do. For example, when the maximum value is Ma, the R-BL drive value is 1.2 Ma, the G-BL drive value is 1.0 Ma, and the B-BL drive value is 0.9 Ma, the drive value limiting unit 210 sets all the backlights. For example, by multiplying the driving value by 0.83, the driving value is limited so as not to exceed the maximum value. As described above, the reason for restricting other than the backlight drive value exceeding the maximum value is to maintain the color balance of the entire RGB.
If the input backlight drive value is less than the predetermined maximum value as a result of the comparison, the drive value limiting unit 210 does not limit the input backlight value. The drive value limiting unit 210 outputs the limited R backlight drive value to the R-BL drive circuit 30, outputs the limited G backlight drive value to the G-BL drive circuit 40, and sets the limited B backlight. The write drive value is output to the B-BL drive circuit 50.

  Next, processing performed by the backlight device 2 will be described. FIG. 5 is a flowchart of a processing procedure performed by the backlight device 2 according to the present embodiment. In FIG. 5, the processes in steps S <b> 1 to S <b> 6 are processes performed by the backlight device 2 during calibration. Further, the processes in steps S7 to S14 are processes performed by the backlight device 2 when setting the white balance.

First, the calibration process will be described.
(Step S <b> 1) The user installs the color sensor 5 on the screen of the display unit 4. Next, the video output device 3 outputs a white video signal to the backlight device 2. Next, the backlight device 2 displays the video signal output from the video output device 3 on the screen of the display unit 4.

(Step S2) When a white video signal is displayed on the screen of the display unit 4, for example, in response to an instruction from the video output device 3, the target luminance calculation unit 203 sets the BL drive value to be near red. To do.
(Step S3) When a white video signal is displayed on the screen of the display unit 4, for example, in response to an instruction from the video output device 3, the target luminance calculation unit 203 sets the BL drive value to be near green. To do.

(Step S4) When a white video signal is displayed on the screen of the display unit 4, for example, in response to an instruction from the video output device 3, the target luminance calculation unit 203 sets the BL drive value to be near blue. To do.
(Step S5) When a white video signal is displayed on the screen of the display unit 4, for example, in response to an instruction from the video output device 3, the target luminance calculation unit 203 sets the BL drive value to be near white. To do.

(Step S6) The BL drive control unit 20 acquires the screen display color (XYZ value; (1) color) measured by the color sensor 5 at Step S2, and uses the acquired screen display color as a primary color calibration point storage unit 2011. Remember me. Next, the BL drive control unit 20 acquires the screen display color (XYZ value; (2) color) measured by the color sensor 5 at step S3, and stores the acquired screen display color in the primary color calibration point storage unit 2011. Remember. Next, the BL drive control unit 20 acquires the screen display color (XYZ value; (3) color) measured by the color sensor 5 at step S4, and stores the acquired screen display color in the primary color calibration point storage unit 2011. Remember. Note that data relating to (1) to (3) colors is referred to as primary color calibration point data. Next, the BL drive control unit 20 acquires the screen display color (XYZ value; (4) color) measured by the color sensor 5 in step S5, and stores the acquired screen display color in the white calibration point storage unit 2012. Remember.
This completes the calibration process. The time required for calibration is, for example, 1 minute. Note that after the calibration is completed, the user removes the color sensor 5 from the display unit 4.

Next, processing when setting white balance will be described.
(Step S <b> 7) The BL luminance calculation unit 202 determines the RGB luminance that is the color space of the backlight based on the primary color calibration point data (colors (1) to (3)) stored in the primary color calibration point storage unit 2011. A color space conversion coefficient for alternately converting the XYZ values is obtained by a known technique.
(Step S8) The BL luminance calculation unit 202 converts the white calibration point data ((4) color) stored in the white calibration point storage unit 2012 into RGB luminance using the obtained color space conversion coefficient.

(Step S9) The BL brightness calculation unit 202 creates a brightness-driving value conversion LUT that is an RGB independent 1D_LUT from the RGB brightness converted in step S8.

(Step S10) The target luminance calculation unit 203 uses the color space conversion coefficient created by the BL luminance calculation unit 202 to convert the target white point (XYZ value) stored in the target white point storage unit 10 into the backlight. Conversion to RGB luminance target values, which are color spaces. Next, the target luminance calculation unit 203 outputs each of the converted RGB luminance target values to the R luminance-drive value conversion unit 207 to the B luminance-drive value conversion unit 209.

(Step S11) Each of the R luminance-driving value conversion unit 207 to the B luminance-driving value conversion unit 209 uses the R luminance target value 204 to the B luminance target value 206 output from the target luminance calculation unit 203 in each conversion LUT. Input to convert to backlight drive value.

(Step S12) The drive value limiting unit 210 receives the backlight drive value converted by the R luminance-drive value conversion unit 207 to the B luminance-drive value conversion LUT 209. Next, the drive value limiting unit 210 determines whether or not the input backlight drive value is less than a predetermined maximum value. When the input backlight driving value is equal to or greater than a predetermined maximum value, the driving value limiting unit 210 limits other backlight driving values according to the backlight driving value exceeding the maximum value. To do. If the input backlight drive value is less than the predetermined maximum value as a result of the comparison, the drive value limiting unit 210 does not limit the input backlight value.

(Step S13) The BL drive control unit 20 outputs the created backlight drive values after the limitation to the R-BL drive circuit 30 to the B-BL drive circuit 50. Next, each of the R-BL driving circuit 30 to the B-BL driving circuit 50 drives the R-BL 61 to B-BL 63 to emit light according to the input backlight driving value.
(Step S <b> 14) The backlight device 2 displays the video signal output from the video output device 3 on the screen of the display unit 4.
This completes the process for setting the white balance. In the present embodiment, the backlight drive value for the target white point (Yxy value) can be specified by the user through these processes.

  As described above, the display device 1 according to this embodiment includes a backlight (for example, R-BL61, G-BL62, and B-BL63), a display unit (for example, the display unit 4) that displays an image, and a backlight. A first measurement value (for example, XYZ) that is a measurement value of the color of the image displayed on the display unit when light is emitted in one color (for example, white) and a backlight in the second color (for example, red) A storage unit (for example, BL characteristic storage unit 201) that stores a second measurement value (for example, RBG) that is a measurement value of the color of the image displayed on the display unit when the light is emitted, and a second measurement value A backlight luminance calculation unit (for example, BL luminance calculation unit 202) that converts the first measurement value into a measurement luminance value that is a value of a color space based on the backlight, using a color space conversion coefficient obtained using First measurement using color space conversion coefficient A target luminance calculation unit (for example, target luminance calculation unit 203) that converts a target white point setting value indicated by a value in the same color space as the target color value into a backlight target luminance value, and a target luminance value using the measured luminance value A drive value conversion unit (for example, an R luminance-drive value conversion unit 207, a G luminance-drive value conversion unit 208, and a B luminance-drive value conversion unit 209) that converts the luminance value into a drive value for the backlight.

  In the display device 1 according to the present embodiment, the storage unit (for example, the BL characteristic storage unit 201) causes the image of the fifth color (for example, white) when the backlight emits light in the second color (for example, red). The second measurement value, which is the measurement value of the color of the image displayed on the display unit based on the signal, is stored as the first primary color calibration point data, and the backlight is caused to emit light in the third color (for example, green). Sometimes the measured value of the color of the image displayed on the display unit based on the image signal of the fifth color is stored as the second primary color calibration point data, and the backlight emits light in the fourth color (for example, blue). The measured value of the color of the image displayed on the display unit based on the image signal of the fifth color is stored as the third primary color calibration point data, and the backlight luminance calculating unit (for example, the BL luminance calculating unit 202) Are the first primary color calibration point data to the third primary color calibration. Data using to determine the color space conversion coefficients.

  With this configuration, the display device 1 of the present embodiment performs calibration by attaching the color sensor 5 to the display device 1 at the time of shipment, writes the measured result in the BL characteristic storage unit 201, and ships. Thereafter, the display device 1 performs white balance adjustment using the data stored in the BL characteristic storage unit 201. Thereby, in the display apparatus 1 of this embodiment, a user does not need to purchase a color sensor.

Further, from the characteristics of the backlight shown in FIG. 3 and FIG. 4, according to the present embodiment, all white points are obtained by only one to several calibration point data measured at the time of one calibration at the time of shipment. Drive values can be configured. As a result, according to the present embodiment, since one calibration is sufficient at the time of shipment, the number of man-hours for adjustment can be reduced.
Further, when used by a user after shipment, correction for aged deterioration can be performed with a single calibration even for a large number of white spot settings.

  In the present embodiment, the LED has been described as an example of the light source of three colors. However, the light source may be, for example, a cold cathode fluorescent tube (CCFL). In this case, since the proportional relationship between the drive value and the light amount described with reference to FIGS. 2 and 3 is reduced, it is preferable to acquire more white calibration points at the time of calibration than when three-color LEDs are used. For example, the white calibration points to be acquired in the case of the display device 1 using three color LEDs are 1 to 3, and the white calibration points to be acquired in the case of the backlight device using the CCFL are 5 to 10 points. It is.

  In the present embodiment, the example in which the backlight is driven by adjusting the duty ratio of the PWM signal has been described. However, the present invention is not limited to this. For example, the current value may be controlled. In this case, in the graph of wavelength and light quantity shown in FIG. 2, the peak of the wavelength changes depending on the drive value, and therefore the accuracy of the display white point may be lowered at a low drive value. For this reason, for example, control may be performed so as to drive with a drive value equal to or greater than a predetermined current value.

[Second Embodiment]
In the display device 1 according to the first embodiment, the example of creating the white light backlight using the RGB three-color backlights has been described, but in this embodiment, the white light using the two-color backlights is generated. An example of creating a backlight will be described.

FIG. 6 is a block diagram of a schematic configuration of the display device 1A according to the present embodiment. As illustrated in FIG. 6, the display device 1 </ b> A includes a backlight device 2 </ b> A and a display unit 4. A video output device 3 and a display unit 4 are connected to the backlight device 2A. In addition, the color sensor 5 is installed on the display unit 4 only during calibration.
Further, the backlight device 2A includes a target white spot storage unit 10, a BL drive control unit 20A, a G-BL drive circuit 40, a B-BL drive circuit 50, a hybrid BL 70, and a video gain adjustment unit 80. In addition, about the function part which has the same function as the backlight apparatus 2 of 1st Embodiment, description is abbreviate | omitted using the same code | symbol.

  The BL drive control unit 20A is controlled so that the BL drive value becomes a wavelength near red, near green, near blue, and near white while the white video signal is displayed on the display unit 4 at the time of calibration. The color sensor 5 to which the display unit 4 is attached receives the measurement result.

  The BL drive control unit 20A alternates between the RGB brightness and the XYZ values, which are the color space of the backlight, based on the XYZ values (primary color calibration point data) measured by the color sensor 5 during BL drive near each color when white balance is set. A color space conversion coefficient to be converted into is generated by a known technique. This color space conversion coefficient is represented by an inner product of 3 rows and 3 columns. Further, the BL drive control unit 20A converts the XYZ values (white calibration point data) measured by the color sensor 5 when white balance is set and the BL drive near white into RGB luminance using the created color space conversion coefficient. . When white balance is set, the BL drive control unit 20A creates a luminance-drive value conversion LUT (LookUp Table) from the converted RGB luminance. The BL drive control unit 20A converts the target white point of the XYZ value into the target luminance of RGB that is the backlight color space using the created color space conversion coefficient. The BL drive control unit 20 </ b> A outputs the converted RGB target luminances to the G-BL drive circuit 40 and the B-BL drive circuit 50.

Further, the BL drive control unit 20A, based on the result of comparing the drive values output to the G-BL drive circuit 40 and the B-BL drive circuit 50, the gain of the B (blue) signal among the RGB video signals. Instruction (also referred to as B video gain) or R (red) signal gain instruction (also referred to as R video gain). The BL drive control unit 20A outputs the generated B signal gain instruction or R signal gain instruction to the video gain adjustment unit 80 as a video signal control value.
The configuration of the BL drive control unit 20A will be described later.

The hybrid BL70 includes G-BL701, B-BL702, and a phosphor 703.
The G-BL 701 is a light source that emits green light in response to a drive signal output from the G-BL drive circuit 40. The center wavelength of green light is, for example, about 540 [nm].
The B-BL 702 is a light source that emits blue light in response to a drive signal output from the B-BL drive circuit 50. The center wavelength of blue light is, for example, about 460 [nm].
The phosphor 703 is a phosphor in a red band, for example, and red light is excited when the G-BL 701 and the B-BL 702 are turned on. The phosphor 703 may be a yellow band phosphor. The red band is, for example, about 620 nm to 750 nm. The yellow band is, for example, about 570 nm to 590 nm. Hereinafter, in the present embodiment, an example in which the phosphor 703 is a red phosphor will be described.

  The video gain adjustment unit 80 adjusts the gain of the B signal or the R signal among the RGB video signals in accordance with the video signal control value output from the BL drive control unit 20A, and outputs the video signal after gain adjustment. It is displayed on the display unit 4.

FIG. 7 is a cross-sectional view of a light source used in the backlight according to the present embodiment. As shown in FIG. 7, the hybrid BL 70 includes a substrate 704, a green LED 701G, a blue LED 702B, and a phosphor 703.
The green LED 701G is formed on the substrate 704.
The blue LED 702B is formed on the substrate 704.
The phosphor 703 is formed on the green LED 701G and the blue LED 702B. In the backlight device 2A, for example, a plurality of hybrid BLs 70 are arranged around the display unit 4, and the display unit 4 is illuminated by diffusing the light emitted from these light sources.

Since the hybrid BL 70 has the structure shown in FIG. 7, when the green LED 701 is turned on, red light is emitted in addition to green light. When the blue LED 702 is turned on, red light is emitted in addition to blue light. In the hybrid BL 70, when the green LED 701 and the blue LED 702 are turned on, the green and blue lights up as described above, and the red color of the phosphor 703 is excited. The hybrid BL 70 generates white light by mixing the light of these three colors.
For example, the center wavelength of red light is about 680 nm, the center wavelength of green light is about 520 nm, and the center wavelength of blue light is about 470 nm. Therefore, in the hybrid BL 70 shown in FIG. 7, the light source having the longest wavelength among the three colors for realizing white is realized by the phosphor 703.

  FIG. 8 is a block diagram of a schematic configuration of the BL drive control unit 20A according to the present embodiment. As shown in FIG. 8, the BL drive control unit 20A includes a BL characteristic storage unit 201, a BL luminance calculation unit 202, a target luminance calculation unit 203, an R luminance-drive value conversion unit 207, a G luminance-drive value conversion unit 208, A B luminance-drive value conversion unit 209, a drive value restriction unit 210A, and a comparison unit 211 are provided. In addition, about the function part which has the same function as BL drive control part 20 of 1st Embodiment, description is abbreviate | omitted using the same code | symbol.

  The comparison unit 211 compares the R backlight driving value and the B backlight driving value output from the R luminance-driving value conversion unit 207 and the B luminance-driving value conversion unit 209, respectively. The comparison unit 211 recreates the B backlight drive value that is the drive value of the B-BL 702 based on the comparison result, and outputs the recreated B backlight drive value to the drive value limiting unit 210A. Further, based on the comparison result, the comparison unit 211 generates a B signal gain instruction (also referred to as B video gain) or an R signal gain instruction (also referred to as R video gain) among the RGB video signals. The generated B signal gain instruction or R signal gain instruction is output to the video gain adjustment unit 80 as a video signal control value.

  The drive value limiting unit 210A receives the B backlight drive value output from the comparison unit 211 and the G backlight drive value output from the G luminance-drive value conversion unit 208. The drive value limiting unit 210A determines whether or not the input backlight drive value is less than a predetermined maximum value. When the input backlight driving value is equal to or greater than a predetermined maximum value, the driving value limiting unit 210 limits other backlight driving values according to the backlight driving value exceeding the maximum value. To do. When the input backlight drive value is less than a predetermined maximum value as a result of the comparison, the drive value limiting unit 210A does not limit the input backlight value. The drive value limiting unit 210A outputs the limited G backlight drive value to the G-BL drive circuit 40, and outputs the limited B backlight drive value to the B-BL drive circuit 50.

  The video gain adjustment unit 80 controls the magnitude of the video signal input from the video output device 3 according to the video signal control value output from the comparison unit 211 of the BL drive control unit 20A, and displays the controlled video signal. Part 4 is displayed.

  Next, processing performed by the backlight device 2A will be described. FIG. 9 is a flowchart of a processing procedure performed by the backlight device 2A according to this embodiment. In FIG. 9, the processes in steps S101 to S108 are processes performed by the backlight device 2A during calibration. Further, the processes in steps S109 to S117 are processes performed by the backlight device 2A when white balance is set.

First, the calibration process will be described.
(Step S <b> 101) The user installs the color sensor 5 on the screen of the display unit 4. Next, the video output device 3 outputs a red video signal to the backlight device 2A. Next, the backlight device 2 </ b> A displays the video signal output from the video output device 3 on the screen of the display unit 4.
(Step S102) When a red video signal is displayed on the screen of the display unit 4, for example, in response to an instruction from the video output device 3, the target luminance calculation unit 203 sets the BL drive value to be near blue. To do.

(Step S103) The video output device 3 outputs a blue video signal to the backlight device 2A. Next, the backlight device 2 </ b> A displays the video signal output from the video output device 3 on the screen of the display unit 4.
(Step S <b> 104) When a blue video signal is displayed on the screen of the display unit 4, for example, in response to an instruction from the video output device 3, the target luminance calculation unit 203 sets the BL drive value to be near blue. To do.

(Step S105) The video output device 3 outputs a white video signal to the backlight device 2A. Next, the backlight device 2 </ b> A displays the video signal output from the video output device 3 on the screen of the display unit 4.
(Step S106) When a white video signal is displayed on the screen of the display unit 4, for example, in response to an instruction from the video output device 3, the target luminance calculation unit 203 sets the BL drive value to be near green. To do.
(Step S107) When a white video signal is displayed on the screen of the display unit 4, for example, in response to an instruction from the video output device 3, the target luminance calculation unit 203 sets the BL drive value to be near white. To do.

(Step S108) The BL drive control unit 20A acquires the screen display color (XYZ value; (11) color) measured by the color sensor 5 at Step S102, and uses the acquired screen display color as the primary color calibration point storage unit 2011. Remember me. Next, the BL drive control unit 20A acquires the screen display color (XYZ value; (12) color) measured by the color sensor 5 at step 104, and stores the acquired screen display color in the primary color calibration point storage unit 2011. Remember. Next, the BL drive control unit 20 acquires the screen display color (XYZ value; (13) color) measured by the color sensor 5 at step S106, and stores the acquired screen display color in the primary color calibration point storage unit 2011. Remember. Note that data relating to (1) to (3) colors is referred to as primary color calibration point data. Next, the BL drive control unit 20 acquires the screen display color (XYZ value; (14) color) measured by the color sensor 5 at step S107, and stores the acquired screen display color in the white calibration point storage unit 2012. Remember.
This completes the calibration process. The time required for calibration is, for example, 1 minute. Note that after the calibration is completed, the user removes the color sensor 5 from the display unit 4.

Next, processing when setting white balance will be described.
(Step S <b> 109) The BL luminance calculation unit 202 calculates the RGB luminance that is the color space of the backlight based on the primary color calibration point data (colors (11) to (13)) stored in the primary color calibration point storage unit 2011. A color space conversion coefficient for alternately converting the XYZ values is obtained by a known technique.
(Step S110) The BL luminance calculation unit 202 converts the white calibration point data ((14) color) stored in the white calibration point storage unit 2012 into RGB luminance using the obtained color space conversion coefficient.

(Step S111) The BL brightness calculation unit 202 creates a brightness-driving value conversion LUT that is an RGB independent 1D_LUT from the RGB brightness converted in Step S110.

(Step S112) The target luminance calculation unit 203 uses the color space conversion coefficient converted by the BL luminance calculation unit 202 to convert the target white point (XYZ value) stored in the target white point storage unit 10 into the backlight. Conversion to RGB luminance target values, which are color spaces. Next, the target luminance calculation unit 203 outputs each of the converted RGB luminance target values to the R luminance-drive value conversion unit 207 to the B luminance-drive value conversion unit 209.

(Step S113) Each of the R luminance-driving value conversion unit 207 to the B luminance-driving value conversion unit 209 converts each of the R luminance target value 204 to the B luminance target value 206 output from the target luminance calculating unit 203 into each driving value conversion. The backlight drive value is created by inputting it into the section.

(Step S114) The B backlight drive value output from the comparison unit 211 and the G backlight drive value output from the G luminance-drive value conversion unit 208 are input to the drive value limiting unit 210A. Next, the drive value limiting unit 210A determines whether or not the input backlight drive value is less than a predetermined maximum value. When the input backlight drive value is equal to or greater than a predetermined maximum value, the drive value limiting unit 210A limits other backlight drive values according to the backlight drive value exceeding the maximum value. To do. When the input backlight drive value is less than a predetermined maximum value as a result of the comparison, the drive value limiting unit 210A does not limit the input backlight value.

(Step S115) The BL drive control unit 20 outputs the created backlight drive values after the limitation to the G-BL drive circuit 40 and the B-BL drive circuit 50, respectively. Next, each of the G-BL drive circuit 40 and the B-BL drive circuit 50 drives the G-BL 701 and B-BL 702 to emit light in accordance with the input backlight drive value.
(Step S116) The video gain adjustment unit 80 adjusts the gain of the B signal or the R signal of the RGB video signals in accordance with the video signal control value output from the BL drive control unit 20A.
(Step S116) The video gain adjusting unit 80 displays the video signal after gain adjustment on the display unit 4.
This completes the process for setting the white balance. In the present embodiment, the backlight drive value for the target white point (Yxy value) can be specified by the user through these processes.

  As described above, in the display device 1A of the present embodiment, the storage unit (for example, the BL characteristic storage unit 201) causes the sixth color (for example, red) when the backlight emits light in the fourth color (for example, blue). ) Is stored as the first primary color calibration point data, and the backlight is in the fourth color (for example, blue). The measurement value of the color of the image displayed on the display unit based on the image signal of the seventh color (for example, blue) when the light is emitted is stored as the second primary color calibration point data, and the backlight is the third color. The measured value of the color of the image displayed on the display unit based on the image signal of the fifth color (for example, white) when emitting light (for example, green) is stored as the third primary color calibration point data, and the backlight The luminance calculation unit (for example, the BL luminance calculation unit 202) Using one of the primary color calibration point data to third primary color calibration point data, we obtain the color space conversion coefficients.

With this configuration, similarly to the first embodiment, the display device 1A of the present embodiment performs calibration for about one minute using the external color sensor 5 in advance, and the white point XYZ values are converted into the brightness values of the BL color space. A color space conversion coefficient to be converted to is obtained. In the present embodiment, the primary color BL drive value for an arbitrary white point designated in Yxy or XYZ units can be calculated from this color space conversion coefficient. In the present embodiment, calibration is not required again when displaying different white spots.
In the present embodiment, therefore, there is an effect that it is possible to omit the color sensor and the calibration work for each target white point that have been conventionally required. Then, by performing calibration at the time of display shipment using the display device 1A of the present embodiment, the display can be displayed with an arbitrary white point (Yxy) value without requiring a built-in BL sensor or an external color sensor.

  In the above, the example in which the backlight device 2 (or 2A) is used for the backlight of the display device has been described in the present invention, but the present invention is not limited to this. The backlight device 2 (or 2A) may be used, for example, as a light source for a projector or a laser television. The backlight device 2 (or 2A) of the present embodiment may also be applied to a portable information terminal, a navigation system, a notification indicator, a digital signage (digital signage), and the like.

A program for realizing the functions of the display device 1 of FIG. 1 or the display device 1A of FIG. 6 of the embodiment is recorded on a computer-readable recording medium, and the program recorded on the recording medium is stored in the computer system. The processing of each unit may be performed by reading and executing. Here, the “computer system” includes an OS and hardware such as peripheral devices.
Further, the “computer system” includes a homepage providing environment (or display environment) if a WWW system is used.
The “computer-readable recording medium” is a portable medium such as a flexible disk, a magneto-optical disk, a ROM (Read Only Memory), a CD-ROM, or a USB (Universal Serial Bus) I / F (interface). A storage device such as a USB memory or a hard disk built in a computer system. Further, the “computer-readable recording medium” includes a medium that holds a program for a certain period of time, such as a volatile memory inside a computer system serving as a server or a client. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

DESCRIPTION OF SYMBOLS 1, 1A ... Display apparatus, 2, 2A ... Backlight apparatus, 3 ... Video output apparatus, 4 ... Display part, 5 ... Color sensor, 10 ... Target white point memory | storage part, 20, 20A ... BL drive control part, 30 ... R-BL drive circuit, 40 ... G-BL drive circuit, 50 ... B-BL drive circuit, 60 ... 3 primary colors BL, 61 ... R-BL, 62,701 ... G-BL, 63,702 ... B-BL, 70 ... Hybrid BL, 80 ... Video gain adjustment unit, 201 ... BL characteristic storage unit, 202 ... BL luminance calculation unit, 203 ... Target luminance calculation unit, 207 ... R luminance-drive value conversion unit, 208 ... G luminance-drive value Conversion unit, 209... B luminance-drive value conversion unit, 210, 210A ... drive value limiting unit, 211 ... comparison unit, 703 ... phosphor, 2011 ... primary color calibration point storage unit, 2012 ... white calibration point storage unit

Claims (10)

With backlight,
A display for displaying an image;
When the backlight is caused to emit light in white color, the first measurement is a measurement of the color of the image displayed on the display unit based on the white image signal, red the backlight, green, A storage unit that stores a second measurement value that is a measurement value of a color of an image displayed on the display unit based on the white image signal when light is emitted in at least one of blue colors;
A backlight luminance calculation unit that converts the first measurement value into a measurement luminance value that is a value of a color space based on the backlight, using a color space conversion coefficient obtained by using the second measurement value; ,
A target luminance calculation unit that converts a target white point setting value indicated by a value in the same color space as the color space of the first measurement value into a target luminance value of the backlight using the color space conversion coefficient;
A driving value conversion unit that converts the target luminance value into a driving value for the backlight using the measured luminance value;
A display device comprising: The storage unit
The backlight when light is emitted by the red, the measured value of the color of the white color of the image displayed on the display unit based on the image signal, and stores a first primary color calibration point data,
The backlight when light is emitted in green, a measurement of the color of the white color of the image displayed on the display unit based on the image signal, and stores as a second primary color calibration point data,
The backlight when light is emitted in blue color, a measurement of the color of the white color of the image displayed on the display unit based on the image signal is stored as the third primary color calibration point data,
The backlight luminance calculation unit
The display device according to claim 1, wherein the color space conversion coefficient is obtained using the first primary color calibration point data to the third primary color calibration point data. The storage unit
Storing the measured value of the color of the image displayed on the display unit based on the image signal of the sixth color when the backlight is emitted in the fourth color as the first primary color calibration point data;
Storing the measured value of the color of the image displayed on the display unit based on the image signal of the seventh color when the backlight is caused to emit light in the fourth color as second primary color calibration point data;
Storing the second measurement value as third primary color calibration point data;
The backlight luminance calculation unit
Using the first primary color calibration point data to third primary color calibration point data, the display device according to claim 1, wherein the determination of the color space transform coefficients. The storage unit
The pre-Symbol first measurement is stored as the white calibration point data,
The backlight luminance calculation unit
4. The display device according to claim 1 , wherein the white calibration point data is converted into the measured luminance value by using the color space conversion coefficient. 5. With backlight,
A display for displaying an image;
When the backlight is caused to emit light in the first color, the first measurement value that is a measurement value of the color of the image displayed on the display unit, and when the backlight is caused to emit light in the second color A storage unit that stores a second measurement value that is a measurement value of the color of the image displayed on the display unit;
A backlight luminance calculation unit that converts the first measurement value into a measurement luminance value that is a value of a color space based on the backlight, using a color space conversion coefficient obtained by using the second measurement value; ,
A target luminance calculation unit that converts a target white point setting value indicated by a value in the same color space as the color space of the first measurement value into a target luminance value of the backlight using the color space conversion coefficient;
A driving value conversion unit that converts the target luminance value into a driving value for the backlight using the measured luminance value;
With
The storage unit
The second measurement value, which is a measurement value of the color of the image displayed on the display unit based on the image signal of the sixth color when the backlight is caused to emit light in the fourth color, is used as the first primary color. Store as calibration point data,
Storing the measured value of the color of the image displayed on the display unit based on the image signal of the seventh color when the backlight is caused to emit light in the fourth color as second primary color calibration point data;
Storing the measured value of the color of the image displayed on the display unit based on the image signal of the fifth color when the backlight is emitted in the third color as the third primary color calibration point data;
The backlight luminance calculation unit
A display device characterized in that a color space conversion coefficient is obtained using the first primary color calibration point data to the third primary color calibration point data . The backlight luminance calculation unit
Using the measured luminance value, further create a conversion table that associates the target luminance value with the driving value,
The drive value converter is
The display device according to any one of claims 1 to 5 , wherein the target luminance value is converted into the drive value using the conversion table. When any of the drive values converted by the drive value conversion unit is greater than or equal to a predetermined maximum value, a restriction that limits other drive values according to the drive value exceeding the maximum value The display device according to claim 1 , further comprising a unit.   The first measurement value and the second measurement value are stored in the storage unit by being measured by a color sensor connected to the display device,
  The backlight luminance calculation unit converts the first measurement value into the measurement luminance value in a state where the color sensor is detached from the display device.
  The display device according to claim 1.   The first measurement value and the second measurement value are XYZ values, respectively, and the measurement luminance value and the target luminance value are RGB values, respectively.
  The display device according to any one of claims 1 to 8. When light is emitted backlight in white color, the first measurement is a measurement of the color of the image displayed on the basis of the white image signal to a display unit for displaying an image, the backlight red, A storage procedure for storing a second measurement value that is a measurement value of a color of an image displayed on the display unit based on the white image signal when light is emitted in at least one of green and blue ; ,
A backlight luminance calculation procedure for converting the first measurement value into a measurement luminance value that is a value of a color space based on the backlight, using a color space conversion coefficient obtained by using the second measurement value; ,
Using the color space conversion coefficient obtained by the backlight luminance calculation procedure, a target white point setting value indicated by a value in the same color space as the color space of the first measurement value is obtained as the target luminance of the backlight. Target luminance calculation procedure to convert to a value,
A drive value conversion procedure for converting the target brightness value into a drive value for the backlight using the measured brightness value converted by the target brightness calculation procedure;
A control method for a display device, comprising:

Images