JP5950566B2 - Image display apparatus and control method thereof - Google Patents

Description

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

A liquid crystal display device is a display device that utilizes the light transmittance of a liquid crystal panel. In a liquid crystal display device, the display is controlled by the light emitted from the backlight installed on the back of the liquid crystal panel being transmitted through the liquid crystal panel and the light emitted from the backlight being blocked by the liquid crystal panel. Is done.
As the light source of the backlight, a plurality of light emitting diodes (hereinafter referred to as LEDs) are used. As LED used for a light source, there exist color LED and WLED, such as RLED, GLED, and BLED, for example. RLED, GLED, BLED, and WLED are LEDs that emit light of R (red), G (green), B (blue), and W (white), respectively.
Specifically, RLED, GLED, and BLED are color LEDs that emit light having peak wavelengths in R, G, and B, respectively, and can obtain light with a very high purity compared to WLEDs. . However, the color LED has lower luminous efficiency than the WLED. Therefore, in order to secure the necessary light quantity, the number of LEDs increases and the power consumption increases as compared with the case where only WLEDs are used.
A WLED is, for example, a combination of a yellow phosphor and a BLED, and the spectrum of emitted light is concentrated at a wavelength having high visibility. Thereby, in WLED, although the color purity is low compared with the said color LED, light with high visual luminance can be obtained.

  In recent years, a liquid crystal display device has been developed that can increase the color purity and luminance of light from a backlight by using LEDs of four colors, RLED, GLED, BLED, and WLED. In the liquid crystal display device described in Patent Document 1, for example, when the luminance is low (when the luminance of the backlight is lowered), the color reproducibility can be improved by lighting only the color LEDs. In addition, when the luminance is high (when increasing the luminance of the backlight), the WLED is also turned on in addition to the color LED, so that the luminance can be increased with less power than when only the color LED is used.

  By the way, there is PWM control as a method for adjusting the luminance and color of LEDs. In PWM control, desired brightness and white balance can be obtained by adjusting the length of the light emission period of each LED. However, in PWM control, since the length of the light emission period of each LED is different, there is a so-called color breakup state in which the backlight instantaneously emits light in R, G, B, or a mixed color of two of them. Will occur.

FIG. 10 is a timing chart showing the operation of the backlight using color LEDs.
The vertical synchronization signal is a signal that becomes L level for a predetermined time every frame period. For example, when the frequency of the vertical synchronization signal is 60 Hz, one frame period is about 16.7 msec.
The ON period of RLED, GLED, and BLED indicates the light emission period of the LED, and the OFF period indicates the OFF period of the LED.
At this time, in the period when the RLED and GLED are turned on and the BLED is turned off (period from time t1 to t2), or during the period when only the RLED is turned on (period from time t2 to t3), the observer (user) Color breakup may be perceived.

Conventional techniques for solving the above problems are disclosed in, for example, Patent Documents 2 to 4.
Specifically, Patent Document 2 discloses that each LED is blinked to shorten a period in which another LED is turned off while another LED is turned on.
Patent Document 3 discloses that white light is always synthesized by shifting the phases of light emission periods between light source units (light source units composed of RLED, GLED, and BLED) that are periodically driven.
Patent Document 4 discloses that the deviation of the light emission period is shortened by aligning the central times of the light emission periods of RLED, GLED, and BLED.

JP 2007-133407 A JP 2008-191248 A JP 2006-164631 A JP-A-2005-208425

The above-described color break-up is likely to be perceived by the user when the luminance or color change from the backlight perceived by the user changes greatly.
However, in the techniques described in Patent Documents 1 to 4, since the above problem is not taken into consideration, there is a possibility that color breakup may be perceived by the user.

  An object of the present invention is to provide a liquid crystal display device and a control method therefor that can more reliably suppress a user from perceiving color breakup.

The image display device of the present invention is
A display panel;
A light emitting means having a plurality of color light sources that emit light of different colors and a white light source that emits white light;
Control means for controlling the light emission period of the white light source;
Have
The light emission intensity, which is the light emission amount per unit time of the plurality of color light sources, is different from each other,
In one frame period, the length of at least 1 Tsunoka la over the light emission period of the light source of said plurality of colored light sources is different from the length of the other light emitting period of the color light sources of the plurality of color light sources,
Wherein, among the portion of the period in which the color light source emits light of the plurality of color light sources, the period in which higher color light emission intensity is turned off, assign light emitting period of the white light source preferentially It is characterized by that.
The image display device of the present invention is
A display panel;
A light emitting means having a plurality of color light sources that emit light of different colors and a white light source that emits white light;
Control means for controlling the light emission period of the white light source;
Have
Within one frame period, the length of the light emission period of at least one color light source of the plurality of color light sources is different from the length of the light emission period of the other color light sources of the plurality of color light sources,
The control means emits light from each color light source up to an end time among a plurality of color change periods obtained by dividing a period during which a part of the plurality of color light sources emits light for each unit time. The light emission period of the white light source during a period in which the value obtained by subtracting the total light emission amount of each color light source up to the start time from the total amount is divided by the sum of the light emission amounts of each color light source up to the start time is larger Preferentially assign
It is characterized by that.

The control method of the image processing apparatus of the present invention includes:
A display panel;
A light emitting means having a plurality of color light sources that emit light of different colors and a white light source that emits white light;
A method for controlling an image display device comprising:
An input step for inputting image data;
A control step for controlling a light emission period of the white light source;
Have
The light emission intensity, which is the light emission amount per unit time of the plurality of color light sources, is different from each other,
In one frame period, the length of at least 1 Tsunoka la over the light emission period of the light source of said plurality of colored light sources is different from the length of the other light emitting period of the color light sources of the plurality of color light sources,
In the control step, of the part of the period in which the color light source emits light of the plurality of color light sources, the period in which higher color light emission intensity is turned off, the light emitting period of the white light source preferentially allocated It is characterized by being able to.
The control method of the image processing apparatus of the present invention includes:
A display panel;
A control method for an image display device, comprising: a light emitting unit having a plurality of color light sources that emit light of different colors and a white light source that emits white light,
An input step for inputting image data;
A control step for controlling a light emission period of the white light source;
Have
Within one frame period, the length of the light emission period of at least one color light source of the plurality of color light sources is different from the length of the light emission period of the other color light sources of the plurality of color light sources,
In the control step, light emission of each color light source up to an end time among a plurality of color change periods obtained by dividing a period in which some of the color light sources emit light for each unit time The light emission period of the white light source during a period in which the value obtained by subtracting the total light emission amount of each color light source up to the start time from the total amount is divided by the sum of the light emission amounts of each color light source up to the start time is larger Is preferentially assigned
It is characterized by that.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress more reliably that a user breaks color perception.

Block diagram showing an example of a functional configuration of a liquid crystal display device according to the present embodiment The figure which shows an example of a structure of the backlight which concerns on a present Example. The flowchart which shows an example of operation | movement of the backlight control part which concerns on a present Example. Timing chart showing an example of the operation of each color LED according to the first embodiment Timing chart which shows an example of operation | movement of each LED which concerns on Example 1. FIG. Timing chart which shows an example of operation | movement of each LED which concerns on Example 1. FIG. Timing chart showing an example of the operation of each color LED according to the first embodiment Timing chart showing an example of the operation of each color LED according to the second embodiment Timing chart which shows an example of operation | movement of each LED which concerns on Example 2. Timing chart showing an example of the operation of a conventional backlight

<Example 1>
Hereinafter, a liquid crystal display device and a control method thereof according to Embodiment 1 of the present invention will be described in detail with reference to the drawings. However, the functions, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention only to those unless otherwise specified. The functions and shapes of the components and components once described in the following description are the same as those in the first description unless otherwise described.

FIG. 1 is a block diagram illustrating an example of a functional configuration of a liquid crystal display device 100 according to Embodiment 1 of the present invention.
The CPU 101 is connected to a ROM and a RAM (not shown). The CPU 101 controls the overall operation of the liquid crystal display device 100 using the RAM as a work memory in accordance with a program stored in the ROM.
The input unit 102 decodes image data input from an image output device (not shown) and outputs the decoded image data to the image processing unit 103.
The image processing unit 103 outputs the image data input from the input unit 102 to the liquid crystal panel 104 after applying desired signal processing such as high image quality processing.

The liquid crystal panel 104 includes a plurality of liquid crystal elements whose transmittance is controlled based on the image data input from the image processing unit 103. The liquid crystal panel 104 is, for example, an active matrix liquid crystal display panel.
The backlight 109 has a plurality of color light sources (color LEDs) that emit light of different colors and a white light source (white LED; WLED) that emits white light.
As the light from the backlight 109 passes through the liquid crystal panel 104, an image based on the image data is displayed on the screen.

The sensor 105 includes a color sensor and a temperature sensor. For example, the color sensor has a structure in which an optical filter of each color is combined with a photodiode.
The sensor control unit 106 can obtain the luminance and chromaticity of the backlight 109 from the detection value acquired from the sensor 105. The sensor control unit 106 has a function of compensating for temperature characteristics of other sensors and the light source of the backlight 109 using the detection value of the temperature sensor.

The backlight control unit 107 increases the light emission period of each LED so that the detection value of the sensor (the luminance and chromaticity of the backlight 109) becomes the target value (target luminance and target chromaticity) stored in the memory 108. (PWM value) is calculated. Then, each LED is driven according to the calculated PWM value.
The backlight control unit 107 calculates the difference between the target value and the detection value of the sensor 105, and feedback-controls the PWM value so that the detection value of the sensor 105 becomes the target value.

Note that a PWM value may be stored in the memory 108 for each target value. In that case, the backlight control unit 107 may acquire the PWM value corresponding to the target value from the memory 108 and drive each LED according to the acquired PWM value. Thereafter, the feedback control may be performed.
Note that the liquid crystal display device 100 includes at least one image quality mode, and has a configuration in which target luminance and target chromaticity are preset according to the image quality mode.
The backlight control unit 107 receives a vertical synchronization signal output when image data is output from the image processing unit 103 to the liquid crystal panel 104, and the PWM value is updated according to the vertical synchronization signal. . That is, each LED is PWM controlled for each frame so that the luminance and chromaticity of the backlight 109 coincide with the target values.

FIG. 2 is a diagram illustrating an example of the configuration of the backlight 109.
The backlight 109 includes a plurality of LED groups 201 arranged in a matrix. The LED group 201 includes a plurality of color LEDs (RLED 202, GLED 203, BLED 204 in this embodiment) having different emission colors and a WLED 205. The RLED 202 is a red LED, the GLED 203 is a green LED, the BLED 204 is a blue LED, and the WLED 205 is a white LED. Further, the RLED 202, the GLED 203, the BLED 204, and the WLED 205 can be individually controlled by the backlight control unit 107.

  In this embodiment, in order to obtain light with target luminance and target chromaticity, the lengths of the light emission periods of a plurality of light sources within one frame period are set to different lengths. In addition, the light emission intensity (the light emission amount per unit time) of each LED is set to a different intensity. For example, the emission intensity of GLED 203: the emission intensity of RLED 202: the emission intensity of BLED 204 = 6: 3: 1. The emission intensity can be controlled according to the current value (the magnitude of the current applied to the LED). The light emission intensity (current value) of each LED corresponding to the target value is stored in the memory 108 in advance. In the above example, the ratio of the emission period length and the emission intensity of the RLED 202, the GLED 203, and the BLED 204 is shown. .

Here, when only the color light source is used as the light source of the backlight 109, color breakage may be perceived by the user during a period in which only some of the color light sources of the backlight 109 emit light. is there. The human eye recognizes the integrated value of the light emission intensity as brightness. Therefore, color breakup is likely to be perceived when the luminance or color change method (change rate) of the light from the backlight 109 perceived by the user changes greatly.
Therefore, in this embodiment, the backlight control unit 107 controls the light emission period of the white light source (WLED).
Specifically, the backlight control unit 107 preferentially assigns the light emission period of the WLED to a period in which only some of the color LEDs emit light. When only the color LED is used as the light source of the backlight 109, the luminance and color change rate of the light from the backlight 109 perceived by the user at the start timing or end timing of the period during which only some of the color LEDs emit light. Changes significantly. By preferentially assigning the light emission period of the WLED to the period in which only some of the color LEDs emit light, the change in the luminance and color change rate can be moderated, and color breakup can be made difficult to perceive. it can.
In addition, the rate of change in luminance varies even during a period in which only some of the color LEDs emit light. Then, color breakup is more easily perceived at the timing when the luminance change rate changes more greatly within the period in which only some of the color LEDs emit light. Therefore, in this embodiment, the backlight control unit 107 assigns the light emission period of the WLED so that the change rate of the luminance gradually changes at such timing. As a result, color breaks that are more easily perceived can be made difficult to perceive.

The processing of the liquid crystal display device 100 according to the first embodiment will be described with reference to the flowchart of FIG. 3 and the timing chart of FIG.
FIG. 3 is a flowchart showing an example of the operation of the backlight control unit 107. The process of this flowchart is started in response to the input of the vertical synchronization signal.
First, the backlight control unit 107 determines the light emission intensity and the length of the light emission period of each LED in the next frame from the target value (or the detection value acquired from the sensor control unit 106 and the target value acquired from the memory 108). (Step S301). In this embodiment, in order to obtain standard white light, the emission intensity of GLED, RLED, and BLED is 6: 3: 1, the length of the RLED emission period is Tr, and the length of the GLED emission period is Tg. Suppose that the length of the light emitting period of the BLED is Tb and the length of the light emitting period of the WLED is Tw. In this step, the light emission intensity of the WLED is also determined. The method for the emission intensity of the WLED will be described later.
At this time, the backlight control unit 107 also performs a process of setting the light emission periods of the RLED, GLED, and BLED. In the present embodiment, the light emission periods of RLED, GLED, and BLED are set so that their start times coincide with each other (for example, their start times coincide with the frame start time).
Next (in step S301), the backlight control unit 107 determines the priority for assigning the light emission period of the WLED for each period based on the light emission intensity and the light emission period of each color LED (step S302). A method for determining the priority will be described later.
And the backlight control part 107 allocates the light emission period of WLED in order from a period with a higher priority (step S303). By this step, the light emission period of the WLED is set.
Next, the backlight control unit 107 drives and controls each LED so that light is emitted during the set light emission period.

FIG. 4 is a timing chart showing an example of the operation of each color LED of the backlight 109. FIG. 4 also shows the priority for each period.
As described above, the human eye recognizes the integrated value of the emission intensity as brightness. Therefore, the change rate of the luminance of the light from the backlight 109 perceived by the user greatly changes at the timing when each color LED is turned off within the period in which only some of the color LEDs emit light. (That is, color breakup is perceived). At time t3 (timing when the RLED is turned off), since all the color LEDs are turned off, no color breakup is perceived. In addition, the change rate of the luminance changes more greatly at the timing when the color LED having higher emission luminance is turned off (that is, color breakup is more easily perceived). Specifically, when GLED emission intensity: RLED emission intensity: BLED emission intensity = 6: 3: 1, time t2 (timing when the GLED is extinguished) is time t1 (timing when the BLED is extinguished). Color breakup is more easily perceived.

Therefore, in this embodiment, among the plurality of luminance change periods, the priority (WLED) is assigned so that the light emission periods of the WLEDs are assigned in order from the period starting from the time when the color light source with higher emission intensity is turned off. The priority for assigning the light emission period is determined. The luminance change period is a period in which some of the plurality of color LEDs emit light, and any of the other color light sources among the plurality of color light sources after any one of the plurality of color light sources is turned off. This is the period until the light goes out.
Specifically, the backlight control unit 107 sets the priority for the period from time t2 to t3 to the first priority and sets the priority for the period from time t1 to t2 to the second priority based on the emission intensity of each color LED. The priority of the period from time t3 to t4 and the period from time t0 to t1 is the third priority. The second priority is lower than the first priority, and the third priority is lower than the second priority.
When the target value (target luminance or target chromaticity) of the liquid crystal display device 100 is changed by a user operation or the like, the light emission period of each LED is changed. Therefore, the backlight control unit 107 performs the above-described priority determination process every time the target value is changed or each time the light emission period or light emission intensity of each LED is changed.

FIG. 5 is a timing chart showing an example of the operation of each LED (including WLED) of the backlight 109. FIG. 5 shows an example in which the length Tw of the light emitting period of the WLED is shorter than the length of the first priority period (period from time t2 to t3). The light emission periods of RLED, GLED, and BLED are the same as those in FIG.
As shown in FIG. 5, the light emission period of the WLED is assigned to the period of the first priority. Further, color breakup is more easily perceived at the timing when the color LEDs are turned off (the start time of the luminance variation period) within the period in which only some of the color LEDs emit light. Therefore, in this embodiment, the light emission period of the WLED is assigned so that the start time of the luminance change period is the same as the start time of the light emission period of the WLED assigned to the luminance change period. Thereby, the change in the luminance change rate can be made more gradual, and color breakup can be made less perceptible. In the example of FIG. 5, the start time of the light emission period of the WLED is the start time t2 of the first priority period. In this embodiment, the light emission intensity of the WLED at this time is the sum of the light emission intensities during the period in which all the color LEDs are lit even when the WLED is lit (time t0 to t1 in FIG. 4). It is set not to change. That is, in FIG. 4, the total value of the emission intensity of the color LEDs is 10 (G = 6, R = 3, B = 1) in the period from time t0 to t1 when all of the RLED, GLED, and BLED are lit. is there. On the other hand, since the RLED (intensity is 3) is lit at times t2 to t3 when the WLED is lit, the emission intensity of the WLED is 7. The light emission period of the WLED is determined according to the target luminance.

  Note that the length Tw of the light emitting period of the WLED may be longer than the length of the first priority period. In that case, the light emission period of the WLED that exceeds the first priority period is the second priority period (time t1 to t2 period), the third priority period (time t0 to t1 period). , Time period from t3 to t4, or both).

For example, the length Tw of the light emitting period of the WLED is longer than the length of the first priority period (time t2 to t3), and the length of the first priority period and the length of the second priority period May be shorter than the combined length (the length of the period from time t1 to time t3). In that case, the light emission period of the WLED is assigned as shown in FIG. In the example of FIG. 6, the entire period of the first priority and a part of the period of the second priority are light emission periods of the WLED. In the example of FIG. 6, the light emission period of the WLED is assigned so that the start time of the luminance change period is the same as the start time of the light emission period of the WLED assigned to the luminance change period. Specifically, the start time of the light emission period of the WLED assigned to the first priority period is t2, and the start time of the light emission period of the WLED assigned to the second priority period is t1. . At that time, the light emission intensity of the WLED at the time t1 to t2 is 1 (the total value of the light emission intensity of the color LEDs is 9 (because R = 3, G = 6, and B = 0).
Further, the light emission period Tw of the WLED may be longer than the times t1 to t3. In that case, the entire period of the first priority, the entire period of the second priority, the part of the entire period of the third priority (the period from time t0 to t1 and the period from time t3 to t4) are all or part of the period. The light emission period of the WLED is used.

As described above, according to the present embodiment, the light emission period of the white light source is preferentially assigned to the period in which only some of the color light sources emit light. Thereby, it can suppress more reliably than the past that a user perceives a color breakup.
Further, according to the present embodiment, among the plurality of luminance change periods, the light emission period of the white light source is allocated in order from the period starting from the time when the color light source with higher emission intensity is turned off. In addition, the light emission period of the white light source is assigned so that the start time of the brightness change period is the same as the start time of the light emission period of the white light source assigned to the brightness change period. Thereby, it can suppress more reliably that a user perceives a color breakup.

In the present embodiment, the light emission intensity is a fixed value, but both the light emission intensity or the light emission period and the light emission intensity may be controlled by feedback control.
In this embodiment, the emission intensity is changed according to the target value. However, the emission intensity may be constant regardless of the target value.
In the present embodiment, an example in which the light source is an LED is shown, but the light source is not limited to an LED. For example, the light source may be a cold cathode tube (CCFL).
In this embodiment, the case where the number of color LEDs included in one LED group is three has been described. However, the number of color LEDs is not limited thereto. The number of color LEDs included in one LED group may be two, or four or more.
In this embodiment, the WLED is also controlled to emit light assuming that the backlight has a high luminance. However, if the backlight has a low luminance and the WLED does not need to emit light, You may suppress perception of a color break using a prior art.
In the present embodiment, the start time of the brightness change period and the start time of the light emission period of the white light source assigned to the brightness change period are the same, but they may be different from each other. If the light emission period of the white light source is assigned to the luminance change period, the change in the luminance change rate can be moderated, and color breakup can be made less perceptible than in the past.

  In the present embodiment, the light emission periods of the plurality of color LEDs are set so that the start times thereof are the same, but the light emission periods of the plurality of color LEDs are not limited thereto. The light emission periods of the plurality of color LEDs may be set so that their end times are the same. The start times of the light emission periods of the plurality of color LEDs may be different from each other, and the end times of the light emission periods of the plurality of color LEDs may be different from each other.

FIG. 7 shows a case where a plurality of color light sources emit light in order (when RLED, GLED, and BLED emit light so that the end times of the light emission periods coincide with each other). In the case where a plurality of color light sources emit light as shown in FIG. 7, the light source having a higher light emission intensity emits light within the period in which only some of the color light sources emit light. The rate of change in luminance changes more greatly. That is, color breakup is more easily perceived at the timing when a light source with higher emission intensity emits light within a period in which only some of the color light sources emit light. Therefore, in such a case, only a part of the plurality of color light sources emits light, and after one of the plurality of color light sources is turned on, The period until any one of the color light sources is turned on may be a luminance change period. Then, among the plurality of luminance change periods, the light emission period of the white light source may be allocated in order from the period in which the end time is the time when the color light source with higher emission intensity is turned on. Thereby, the change in the luminance change rate can be moderated, and color breakup can be made less perceptible than in the past. In such a case, it is preferable to assign the light emission period of the white light source so that the end time of the brightness change period and the end time of the light emission period of the white light source assigned to the brightness change period are the same. Thereby, the change in the luminance change rate can be made more gradual, and color breakup can be made less perceptible.
FIG. 7 shows an example in the case of GLED emission intensity: RLED emission intensity: BLED emission intensity = 6: 3: 1. In the example of FIG. 7, the priority of the period from time t1 to t2 is the first priority, the priority of the period from time t2 to t3 is the second priority, the period from time t3 to t4, and the period from time t0 to t1. The priority is the third priority. Then, the light emission period of the white light source is sequentially assigned to the period of the first priority, the period of the second priority, and the period of the third priority.

<Example 2>
Hereinafter, a liquid crystal display device and a control method thereof according to Embodiment 2 of the present invention will be described in detail with reference to the drawings. In the description of the second embodiment, the description of the parts common to the first embodiment will be omitted as appropriate.
In the first embodiment, the specific configuration for gradual change in the change rate of the luminance perceived by the user (luminance of light from the backlight) has been described. In the present embodiment, a specific configuration for gradual change in the change rate of the color perceived by the user (the color of light from the backlight) will be described.

  The general flow of the operation of the backlight control unit 107 according to the second embodiment is the same as that of the first embodiment (FIG. 3). However, in the present embodiment, the process for determining the priority of each period (the process in step S302 in FIG. 3) is different from that in the first embodiment. This will be described in detail below.

  In the present embodiment, the backlight control unit 107 assigns the light emission periods of the WLEDs in order from a period in which the color change amount described later is larger among the plurality of color change periods. The plurality of color change periods are obtained by dividing the period from when any one of the plurality of color light sources is turned off until all the plurality of color light sources are turned off (all color light sources) per unit time. It is a period.

Assuming that the emission intensity of RLED, GLED, and BLED is dR, dG, and dB, the color amount dC (t) at time t can be calculated by the following Equation 1.

dC (t) = dR × (length of light emitting period of RLED up to time t)
+ DG × (the length of the GLED emission period until time t)
+ DB × (length of light emission period of BLED up to time t)
... (Formula 1)

Therefore, the color change amount dVC between time t + 1 and time t is calculated by the following equation 2. The color change amount dVC calculated in this way represents the degree of change in the color change rate (change at time t).

dVC = (dC (t + 1) −dC (t)) / dC (t) (Equation 2)

In this embodiment, the color change amount of each color change period is calculated by performing the above calculation for each color change period. Specifically, the color change amount in the color change period is a value obtained by subtracting the sum of the light emission amounts of the respective color light sources up to the start time of the period from the sum of the light emission amounts of the respective color light sources up to the end time of the period. , By dividing by the total light emission amount of each color light source up to the start time of the period.

FIG. 8 is a timing chart showing an example of the operation of each color LED of the backlight 109. FIG. 8 also shows the priority for each period.
GLED emission intensity: RLED emission intensity: BLED emission intensity = 6: 3: 1, and when time t0 = 0, t1 = 1, t2 = 2, t3 = 3, t4 = 4, time t1 to t4 The amount of color at each time is expressed by the following equations 3-1 to 3-4.

dC (t1) = (3 × 1) + (6 × 1) + (1 × 1) = 10 (Equation 3-1)
dC (t2) = (3 × 2) + (6 × 1) + (1 × 2) = 14 (Equation 3-2)
dC (t3) = (3 × 3) + (6 × 1) + (1 × 3) = 18 (Equation 3-3)
dC (t4) = (4 × 3) + (6 × 1) + (1 × 3) = 21 (Equation 3-4)

The amount of color change in each color change period (period a from time t1 to t2, period b from time t2 to t3, period c from time t3 to t4) is expressed by the following equations 4-1 to 4-3.

DVC of period a == (14−10) /10=0.4 (formula 4-1)
DVC in period b = (18-14) /14=0.28 (formula 4-2)
DVC in period c = (21−18) /18=0.16 (Equation 4-3)

From the expressions 4-1 to 4-3, it can be seen that the change in the color change rate is the largest at the start time of the period a, and the color breakage is most easily perceived in the period a. It can be seen that the change in the color change rate is large at the start time of the period b second, and at the start time of the period c third. That is, it can be seen that color breakage is easily perceived in the second period b and third in period c.
From the expressions 4-1 to 4-3, the backlight control unit 107 sets the priority of the period a as the first priority, the priority of the period b as the second priority, the priority of the period c as the third priority, And the priority of the remaining period (period of time t0-t1 and period of time t4-t5) is made into the 4th priority. The second priority is lower than the first priority, the third priority is lower than the second priority, and the fourth priority is lower than the third priority.

FIG. 9 is a timing chart showing an example of the operation of each LED (including WLED) of the backlight 109. FIG. 9 shows an example in which the length Tw of the light emitting period of the WLED is 3. The light emission periods of RLED, GLED, and BLED are the same as those in FIG.
The priority of the period a is the first priority, the priority of the period b is the second priority, the priority of the period c is the third priority, and the remaining periods (periods t0 to t1 and time) The priority in the period from t4 to t5 is the fourth priority. Therefore, the light emission period of the WLED is assigned in the order of period a, period b, period c, and remaining period. As a result, in the example of FIG. 9, the period of length 3 from the timing when the GLED is turned off (time t1) is the light emission period of the WLED.

  As described above, according to the present embodiment, among the plurality of color change periods, the light emission periods of the white light source are allocated in order from the period in which the color change amount is larger. Thereby, it can suppress more reliably that a user perceives a color breakup.

In this embodiment, the case where the light emission periods of the plurality of color LEDs are set so that their start times are the same has been described as an example, but the light emission periods of the plurality of color LEDs are not limited to this. The light emission periods of the plurality of color LEDs may be set so that their end times are the same. The start times of the light emission periods of the plurality of color LEDs may be different from each other, and the end times of the light emission periods of the plurality of color LEDs may be different from each other.
When a plurality of color light sources emit light in order, the period from when any one of the plurality of color light sources is turned on until all of the plurality of color light sources (all color light sources) are turned on every unit time. A plurality of periods obtained by dividing may be a plurality of color change periods. The priority of each color change period may be determined by the same method as described above.

DESCRIPTION OF SYMBOLS 100 Liquid crystal display device 104 Liquid crystal panel 107 Backlight control part 109 Backlight

Claims (20)

A display panel;
A light emitting means having a plurality of color light sources that emit light of different colors and a white light source that emits white light;
Control means for controlling the light emission period of the white light source;
Have
The light emission intensity, which is the light emission amount per unit time of the plurality of color light sources, is different from each other,
In one frame period, the length of at least 1 Tsunoka la over the light emission period of the light source of said plurality of colored light sources is different from the length of the other light emitting period of the color light sources of the plurality of color light sources,
Wherein, among the portion of the period in which the color light source emits light of the plurality of color light sources, the period in which higher color light emission intensity is turned off, assign light emitting period of the white light source preferentially An image display device characterized by that. The image display device according to claim 1, wherein the light emission periods of the plurality of color light sources are different from each other within one frame period. The plurality of color light sources include three or more color light sources that emit light of different colors ,
Before SL control means, respectively, a part of a period in which the color light source emits light of the plurality of color light sources, one of the plurality of color light sources and from the plurality of color light sources off Among the plurality of luminance change periods, which are periods until one of the other color light sources is turned off, the white light source in order from the period starting from the time when the color light source with higher emission intensity is turned off. The image display device according to claim 1, wherein the light emission period is assigned. The control means assigns the light emission period of the white light source so that the start time of the brightness change period and the start time of the light emission period of the white light source assigned to the brightness change period are the same. The image display device according to claim 3. The plurality of color light sources include three or more color light sources that emit light of different colors ,
Before SL control means, respectively, a part of a period in which the color light source emits light of the plurality of color light sources, one of the plurality of color light sources and from the plurality of color light source lighting Among the plurality of luminance change periods, which are periods until one of the other color light sources is turned on, the white light source in order from the period whose end time is the time when the color light source with higher emission intensity is turned on The image display device according to claim 1, wherein the light emission period is assigned. The control means assigns the light emission period of the white light source so that the end time of the luminance change period is the same as the end time of the light emission period of the white light source assigned to the brightness change period. The image display device according to claim 5. A display panel;
A light emitting means having a plurality of color light sources that emit light of different colors and a white light source that emits white light;
Control means for controlling the light emission period of the white light source;
Have
Within one frame period, the length of the light emission period of at least one color light source of the plurality of color light sources is different from the length of the light emission period of the other color light sources of the plurality of color light sources,
The control means emits light from each color light source up to an end time among a plurality of color change periods obtained by dividing a period during which a part of the plurality of color light sources emits light for each unit time. The light emission period of the white light source during a period in which the value obtained by subtracting the total light emission amount of each color light source up to the start time from the total amount is divided by the sum of the light emission amounts of each color light source up to the start time is larger Preferentially assign
An image display device characterized by that . Within one frame period, the lengths of the light emission periods of the plurality of color light sources are different from each other.
The image display device according to claim 7. The plurality of color light sources include three or more color light sources that emit light of different colors,
The light emission intensity, which is the light emission amount per unit time of the plurality of color light sources, is different from each other,
The control means is a period during which a part of the plurality of color light sources emits light, from when one of the plurality of color light sources is turned off until all of the plurality of color light sources are turned off. Among the plurality of color change periods obtained by dividing the period by the unit time, the sum of the light emission amounts of the respective color light sources up to the start time is subtracted from the sum of the light emission amounts of the respective color light sources up to the end time. values, in order from the light emission amount of the division value is greater than the period the sum of the color light sources to the start time, the image display according to claim 7 or 8, characterized in that assigning a light emission period of the white light source apparatus. The plurality of color light sources include three or more color light sources that emit light of different colors,
The light emission intensity, which is the light emission amount per unit time of the plurality of color light sources, is different from each other,
The control means is a period during which a part of the plurality of color light sources emits light, from when one of the plurality of color light sources is turned on until all of the plurality of color light sources are turned on. Among the plurality of color change periods obtained by dividing the period by the unit time, the sum of the light emission amounts of the respective color light sources up to the start time is subtracted from the sum of the light emission amounts of the respective color light sources up to the end time. values, in order from the light emission amount of the division value is greater than the period the sum of the color light sources to the start time, the image display according to claim 7 or 8, characterized in that assigning a light emission period of the white light source apparatus. A display panel;
A light emitting means having a plurality of color light sources that emit light of different colors and a white light source that emits white light;
A method for controlling an image display device comprising:
An input step for inputting image data;
A control step for controlling a light emission period of the white light source;
Have
The light emission intensity, which is the light emission amount per unit time of the plurality of color light sources, is different from each other,
In one frame period, the length of at least 1 Tsunoka la over the light emission period of the light source of said plurality of colored light sources is different from the length of the other light emitting period of the color light sources of the plurality of color light sources,
In the control step, of the part of the period in which the color light source emits light of the plurality of color light sources, the period in which higher color light emission intensity is turned off, the light emitting period of the white light source preferentially allocated A method for controlling an image display device. 12. The method of controlling an image display device according to claim 11 , wherein the lengths of the light emission periods of the plurality of color light sources are different from each other within one frame period. The plurality of color light sources include three or more color light sources that emit light of different colors ,
In the previous SL control step, respectively, a part of a period in which the color light source emits light of the plurality of color light sources, one of the plurality of color light sources and from the plurality of color light sources off Among the plurality of luminance change periods, which are periods until one of the other color light sources is turned off, the white light source in order from the period starting from the time when the color light source with higher emission intensity is turned off. control method of an image display apparatus according to claim 11 or 12, characterized in that the light emission period is allocated. In the control step, the light emission period of the white light source is assigned such that the start time of the brightness change period is the same as the start time of the light emission period of the white light source assigned to the brightness change period. The method for controlling an image display device according to claim 13 . The plurality of color light sources include three or more color light sources that emit light of different colors ,
In the previous SL control step, respectively, a part of a period in which the color light source emits light of the plurality of color light sources, one of the plurality of color light sources and from the plurality of color light source lighting Among the plurality of luminance change periods, which are periods until one of the other color light sources is turned on, the white light source in order from the period whose end time is the time when the color light source with higher emission intensity is turned on control method of an image display apparatus according to claim 11 or 12, characterized in that the light emission period is allocated. In the control step, the light emission period of the white light source is assigned so that the end time of the brightness change period is the same as the end time of the light emission period of the white light source assigned to the brightness change period. The method for controlling an image display device according to claim 15 . A display panel;
A control method for an image display device, comprising: a light emitting unit having a plurality of color light sources that emit light of different colors and a white light source that emits white light,
  An input step for inputting image data;
  A control step for controlling a light emission period of the white light source;
Have
  Within one frame period, the length of the light emission period of at least one color light source of the plurality of color light sources is different from the length of the light emission period of the other color light sources of the plurality of color light sources,
  In the control step, light emission of each color light source up to an end time among a plurality of color change periods obtained by dividing a period in which some of the color light sources emit light for each unit time The light emission period of the white light source during a period in which the value obtained by subtracting the total light emission amount of each color light source up to the start time from the total amount is divided by the sum of the light emission amounts of each color light source up to the start time is larger Is preferentially assigned
And a control method for the image display device. Within one frame period, the lengths of the light emission periods of the plurality of color light sources are different from each other.
The method for controlling an image display device according to claim 17. The plurality of color light sources include three or more color light sources that emit light of different colors,
The light emission intensity, which is the light emission amount per unit time of the plurality of color light sources, is different from each other,
In the control step, a part of the plurality of color light sources emits light, and from when one of the plurality of color light sources is turned off until all of the plurality of color light sources are turned off. Among the plurality of color change periods obtained by dividing the period by the unit time, the sum of the light emission amounts of the respective color light sources up to the start time is subtracted from the sum of the light emission amounts of the respective color light sources up to the end time. The image according to claim 17 or 18 , wherein the light emission period of the white light source is assigned in order from a period in which a value obtained by dividing the value by the sum of the light emission amounts of the respective color light sources up to the start time is larger. Display device control method. The plurality of color light sources include three or more color light sources that emit light of different colors,
The light emission intensity, which is the light emission amount per unit time of the plurality of color light sources, is different from each other,
In the control step, a part of the plurality of color light sources emits light, and from when one of the plurality of color light sources is turned on until all of the plurality of color light sources are turned on. Among the plurality of color change periods obtained by dividing the period by the unit time, the sum of the light emission amounts of the respective color light sources up to the start time is subtracted from the sum of the light emission amounts of the respective color light sources up to the end time. The image according to claim 17 or 18 , wherein the light emission period of the white light source is assigned in order from a period in which a value obtained by dividing the value by the sum of the light emission amounts of the respective color light sources up to the start time is larger. Display device control method.

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