JP2000028984A - Display control method for liquid crystal display device and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device which can adjust the chromaticity of display color and can adjust the color balance in a wide range with a low-cost and small-sized constitution. SOLUTION: A liquid crystal panel 21 which has plural liquid crystal picture elements and plural switching elements provided correspondingly to individual picture elements, a back light 22 which is arranged on the rear face of the liquid crystal panel 21 and emits red, green, and blue light, and a data driver 32 and a scan driver 33 which switch respective switching elements correspondingly to red, green and blue data of individual picture elements are provided, and emission times of red, green, and blue light of the back light 22 are made different to emit them in time division.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color light source type liquid crystal display device which performs full-color display by causing a backlight of three color lights to emit light in a time division manner, and a display control method thereof.

[0002]

2. Description of the Related Art With the progress of so-called office automation in recent years, OA equipment represented by a word processor, a personal computer and the like has been widely used. Furthermore, the spread of OA equipment in such offices has led to a portable OA that can be used both in offices and outdoors.
There is a demand for devices, and there is an increasing demand for smaller and lighter devices. A liquid crystal display device is widely used as one of means for achieving such an object. In particular, a liquid crystal display device is an indispensable technology not only for reducing the size and weight but also for reducing the power consumption of a portable OA device driven by a battery.

[0003] The liquid crystal display devices are roughly classified into a reflection type and a transmission type. The reflective type is a configuration in which light rays incident from the surface of the liquid crystal panel are reflected on the bottom surface of the liquid crystal panel, and the image is visually recognized by the reflected light. This is a configuration in which an image is visually recognized using transmitted light. The reflection type is inferior in visibility because the amount of reflected light is not constant depending on environmental conditions, but is inexpensive. It is not suitable for a display device such as a personal computer that performs color or full-color display. For this reason, a transmissive display device is generally used as a display device such as a personal computer for performing multi-color or full-color display.

On the other hand, the current color liquid crystal display device has a STN (Super Twisted Nemati) in view of the liquid crystal material used.
c) Type and TFT-TN (Thin Film Transistor-Twist
ed Nematic) type. The STN type has a relatively low manufacturing cost, but has a problem that it is not suitable for displaying a moving image because crosstalk is easily generated and a response speed is relatively slow. On the other hand, TFT-T
The N type has a higher display quality than the STN type,
Since the transmittance of the liquid crystal panel is only about 4% at present, a high-luminance backlight is required. Therefore, the TFT-
In the TN type, there is a problem in use when carrying a battery power because the power consumption by the backlight increases. In addition, the TFT-TN type has problems such as a low response speed, particularly a halftone response speed, a narrow viewing angle, and difficulty in adjusting the color balance.

Further, the conventional transmissive liquid crystal display device is configured to perform multi-color or full-color display by using a white light backlight and selectively transmitting white light with three primary color filters. Color filter type was common. However, in such a color filter type, since a display pixel is configured with a range of adjacent three color filters as one unit, the resolution is substantially reduced to ３.

In view of the above, a ferroelectric liquid crystal element or an antiferroelectric liquid crystal element having a high response speed to an applied electric field is used as a liquid crystal element, and the same pixel is substantially light-emitting in three primary colors by time division. There has been proposed a color liquid crystal display device which does not cause a significant reduction in resolution (Japanese Patent Application Laid-Open No. 7-281150).

This color liquid crystal display device has a liquid crystal panel using a ferroelectric liquid crystal element or an antiferroelectric liquid crystal element capable of high-speed response on the order of several hundreds to several microseconds, and a liquid crystal panel that emits red, green and blue light. By combining a backlight capable of emitting light by division and synchronizing switching of the liquid crystal element and light emission of the backlight, color display is possible. When a ferroelectric liquid crystal or an antiferroelectric liquid crystal is used as the liquid crystal material, the viewing angle becomes extremely wide because the liquid crystal molecules are always parallel to the substrate (glass substrate) regardless of the applied voltage. There is no practical problem. Further, in the case where a backlight using red, green, and blue light emitting diodes (LEDs) is used, the color balance can be adjusted by controlling the current flowing through each LED.

FIG. 13 is a time chart showing an example of a conventional display control method in such a color liquid crystal display device. FIG. 13 (a) shows the light emission timing of each color LED of the backlight, and FIG. 13 (b). Indicates the scanning timing of each line of the liquid crystal panel.

As shown in FIG. 13A, the LEDs of the backlight are sequentially emitted in the order of red, green, and blue, for example, every 5.6 ms, and each pixel of the liquid crystal panel is synchronized with each other in line units. Display is performed by switching with. When displaying 60 frames per second, the period of one frame is 16.6 ms, and the period of one frame is further reduced.
Divided into three subframes of 5.6 ms each, for example, as shown in FIG.
In the example shown in (a), the red LED is used in the first sub-frame, and the green LE is used in the second sub-frame.
D causes the blue LEDs to emit light in the third sub-frame, respectively.

On the other hand, as shown in FIG.
For the liquid crystal panel, data scanning is performed twice during each of the sub-frames of red, green, and blue. However, the start timing of the first scan (data write scan) (timing to the first line) matches the start timing of each subframe, and the end timing of the second scan (data erase scan) (final scan). (Timing to the line) is adjusted so as to coincide with the end timing of each subframe.

In the data writing scan, a voltage corresponding to the pixel data is supplied to each pixel of the liquid crystal panel, and the transmittance is adjusted. As a result, full-color display becomes possible. In the data erase scan, the same voltage as the data write scan and the opposite voltage are supplied to each pixel of the liquid crystal panel, the display of each pixel of the liquid crystal panel is erased, and the application of a DC component to the liquid crystal is prevented. Is done.

[0012]

In the above-mentioned conventional color liquid crystal display device, as is apparent from FIG. 13, the emission times of red, green and blue by the backlight are the same, and the chromaticity of the display color is It is adjusted only by the red, green, and blue emission intensities. For this reason, for example, when an LED is used as a light source, the emission luminance of the red LED is lower than the emission luminance of each of the green and blue LEDs. Therefore, in order to adjust the chromaticity of the display color, the red LED is used. There is a problem that it is necessary to use more LEDs than green and blue LEDs, resulting in an increase in cost. In addition, since many red LEDs need to be installed, there is also a problem of a space for the light source unit.

One of the great features of such a color liquid crystal display device is that the color balance can be adjusted. One of the major features of the color liquid crystal display device is that it cannot be adjusted only by the light emission intensity of the LED. However, there is a problem that the adjustment range is limited due to the limitation of the drive current to the LED.

The present invention has been made in view of such circumstances, and provides a display control method and a liquid crystal display device of a liquid crystal display device capable of adjusting the chromaticity of a display color with a low cost and small configuration. With the goal.

Another object of the present invention is to provide a display control method of a liquid crystal display device and a liquid crystal display device which can adjust the color balance in a wide range.

[0016]

According to a first aspect of the present invention, there is provided a display control method for a liquid crystal display device, wherein a switching element corresponding to each pixel of a liquid crystal panel is provided with a switching element corresponding to three color data of each pixel. In the display control method of the liquid crystal display device, which performs switching during the display period and time-divisionally emits three-color light of the backlight during each display period in synchronization with the switching of the switching element, the emission time of each of the three-color light of the backlight Characterized in that at least two of them are different.

In the display control method for a liquid crystal display device according to the first aspect, the light emission time of the three colors (red, green, and blue) by the backlight is not fixed, and the light emission time is adjusted according to each light emission intensity. Then, the liquid crystal panel is switched according to the light emission sequence. Therefore, even if the intensity balance of each light source of three colors (red, green, and blue) is lost, the chromaticity of the display color at the time of mixing can be adjusted by each light emission time. Therefore, the influence of the light source with low intensity, for example, a large number of light sources
Problems such as a large installation space and difficulty in heat radiation can be solved.

According to a second aspect of the present invention, in the display control method of the liquid crystal display device according to the first aspect, the light emission time and / or the light emission intensity of each of the three color lights of the backlight is variable.

According to a second aspect of the present invention, there is provided a display control method for a liquid crystal display device, wherein one or both of the light emission time and the light emission intensity of each of the three colors (red, green, and blue) of the backlight are variable. Thereby, the chromaticity of the display color can be adjusted. Further, the color balance can be adjusted. When both the light emission time and the light emission intensity are variable, the color balance can be adjusted over a wider range than when only one of them is changed.

According to a third aspect of the present invention, in the display control method of the liquid crystal display device according to the first or second aspect, a total of light emission times of the three colors of light of the backlight is 1/60 second or less.

According to the display control method of the liquid crystal display device of the third aspect, image display for one frame is completed in 1/60 second or less, and display of 60 frames per second is possible.

According to a fourth aspect of the present invention, there is provided a liquid crystal display device comprising: a liquid crystal panel having a plurality of liquid crystal pixels and a plurality of switching elements provided corresponding to each of the liquid crystal pixels; A liquid crystal display device comprising: a backlight that emits light; and a driving unit that switches the switching element in accordance with data of three colors of the liquid crystal pixels. , And backlight control means for performing time-division light emission with different settings.

According to the liquid crystal display device of the present invention, the backlight control means can change the emission time of the three colors (red, green, blue) by the backlight, and can change the three colors (red, green, blue).
Even when the light sources (green, blue) are not balanced in intensity, it is possible to adjust the display color at the time of mixing by controlling the respective light emission times. It is also possible to adjust the color balance over a wide range.

According to a fifth aspect of the present invention, there is provided a liquid crystal display device.
In the backlight, an LED that emits light of each of the three colors, a diffusion plate that diffuses the light emitted by the LED,
A light guide plate for guiding light emitted by the LED to one surface of the liquid crystal panel.

In the liquid crystal display device according to the fifth aspect, the backlight has LEDs of three colors (red, green, and blue), a diffusion plate for diffusing the light emitted by these LEDs, and an LED that emits light. And the light guide plate for guiding the light to one surface of the liquid crystal panel, the transmitted light from the backlight becomes uniform.

The liquid crystal display device according to the sixth aspect is the fourth aspect.
(5) In the liquid crystal panel as described in (5), the liquid crystal material of the liquid crystal panel is a ferroelectric liquid crystal material or an antiferroelectric liquid crystal material.

In the liquid crystal display device according to the sixth aspect, since the liquid crystal material is a ferroelectric liquid crystal material or an antiferroelectric liquid crystal material, high-speed on / off control is possible, and light emission control of the backlight is performed. It is possible to cope with it.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments.

FIG. 1 is a block diagram of a configuration example of a liquid crystal display device according to the present invention, FIG. 2 is a schematic sectional view of the liquid crystal panel and a backlight, and FIG. 3 is a schematic diagram showing a configuration example of a liquid crystal panel and a backlight. FIG. 4 is a schematic view showing a configuration example of an LED array which is a light source of a backlight.

In FIG. 1, reference numerals 21 and 22 denote a liquid crystal panel and a backlight, the cross-sectional structure of which is shown in FIG. The backlight 22 includes an LED array 7 and a light guide plate + light diffusion plate 6, as shown in FIG.

The liquid crystal panel 21 is constructed as a structure between two polarizing films 1 and 5, as shown in FIGS. Specifically, the liquid crystal panel 21 is configured by laminating a polarizing film 1, a glass substrate 2, a common electrode 3, a glass substrate 4, and a polarizing film 5 in this order from the upper side to the lower side. Pixel electrodes 40 corresponding to individual display pixels arranged in a matrix are formed on the surface on the electrode 3 side. A liquid crystal drive control unit 50 including a data driver 32 and a scan driver 33 described later is connected between the common electrode 3 and the pixel electrode 40. Each pixel electrode 40 is provided with a TFT (Thin Fil
m Transistor) 41 is controlled on / off by each T
The FT 41 is driven by selectively turning on / off the signal line 42 by the data driver 32 and the scanning line 43 by the scan driver 33. The transmitted light intensity of each pixel is controlled by a signal from the signal line 42.

An alignment film 12 is disposed on the upper surface of the pixel electrode 40 on the glass substrate 4, and an alignment film 11 is disposed on the lower surface of the common electrode 3. A liquid crystal material is filled between the alignment films 11 and 12. Thus, a liquid crystal layer 13 is formed. Reference numeral 14 denotes a spacer for appropriately holding the thickness of the liquid crystal layer 13.

The backlight 22 is located on the lower layer (back side) of the liquid crystal panel 21 and has an LED array 7 protruding from one side of the light guide plate + light diffusion plate 6 constituting the light emitting area. The LED array 7 has three primary colors, namely, red (R), green (G), and blue (B), on a surface facing the light guide plate + light diffusion plate 6, as shown in FIG. LEDs that emit light of each color are sequentially and repeatedly arranged.
The light guide plate + light diffusion plate 6 functions as a light emitting area by guiding light emitted from each LED of the LED array 7 to the entire surface thereof and diffusing the light to the upper surface.

In FIG. 1, display data DD to be displayed by the liquid crystal panel 21 is given to an image memory 30 from an external device such as a personal computer. After temporarily storing the display data DD, the image memory 30 outputs data of each pixel (hereinafter, referred to as pixel data PD) in synchronization with a synchronization signal SYN generated by the control signal generation circuit 31. The pixel data PD output from the image memory 30
Is input to the selector 37 as it is, and is also supplied to the inverse data generation circuit 36.

The inverse data generation circuit 36 is a circuit for generating the inverse data of the pixel data PD output from the image memory 30, and the output signal is given to the selector 37 as the inverse pixel data #PD. Therefore, the selector 37 has an image memory
The pixel data PD output from 30 and the inverse data generation circuit 36
The selector 37 outputs one of them to the data driver 32 according to the control signal CS given from the control signal generation circuit 31. The data driver 32 controls on / off of the signal line of the pixel electrode 40 according to the pixel data PD or the inverse pixel data #PD output from the selector 37.

The synchronization signal SYN generated by the control signal generation circuit 31 is supplied to the scan driver 33 and the reference voltage generation circuit 34
To the backlight control circuit and the driving power supply 35. The scan driver 33 controls on / off of the scanning line of the pixel electrode 40 in synchronization with the synchronization signal SYN. Further, the reference voltage generating circuit 34 outputs the synchronization signal SYN
A reference voltage VR is generated in synchronization with the data driver 32 and supplied to the data driver 32 and the scan driver 33. The backlight control circuit and the drive power supply 35 apply a drive voltage to the backlight 22 in synchronization with the synchronization signal SYN, and the LED of the backlight 22
The array 7 emits light.

The display operation of the liquid crystal display device of the present invention will be described below. FIG. 5 is a time chart for explaining the principle of the first embodiment of the display control method of the liquid crystal display device of the present invention, and FIG. 5A shows the light emission timing of the LEDs of each color of the backlight 22. FIG. 5B shows the scanning timing of each line of the liquid crystal panel 21.

As shown in FIG. 5A, the backlight 22
Are sequentially emitted in the order of red, green, and blue, and display is performed by switching each pixel of the liquid crystal panel 21 line by line in synchronization with the LED. At this time, the red, green, and blue light emission times are not the same, and the red light emission time is 8.33 ms, the green,
Each light emission time of blue is set to 4.17 ms. In other words, 60 per second
When displaying frames, the duration of one frame is 16.67
ms, and this one frame period is further increased by 8.33 ms to 1
One sub-frame and two sub-frames of 4.17 ms each, and the red LED of the backlight 22 in the first sub-frame (8.33 ms) and the backlight in the second sub-frame (4.17 ms) 22 green LE
D causes the blue LED of the backlight 22 to emit light under the control of the backlight control circuit and the drive power supply 35 in the third sub-frame (4.17 ms).

As described above, the first subframe is 8.33 ms, and the second and third subframes are 4.17 ms.
If one frame is set to 16.67 ms (1/60 s), 60 frames can be displayed in one second, so that the display flicker is not generally recognized by human eyes. However, this is merely an example, and it goes without saying that 30 frames may be displayed per second, for example, as in a television broadcast.

On the other hand, as shown in FIG.
The data driver 32 and the scan driver 33 perform data writing scanning twice on the liquid crystal panel 21 during red, green, and blue sub-frames. However, the start timing (write timing to the first line) of the first write scan (data write scan) coincides with the start timing of each subframe, and the end of the second write scan (data erase scan). The timing is adjusted so that the timing (write timing to the last line) matches the end timing of each subframe.

Further, in the first write scan (data write scan), the control signal CS
Accordingly, pixel data PD is output from the selector 37, and a signal of a voltage corresponding to the pixel data PD output from the selector 37 is supplied from the data driver 32 to each pixel of the liquid crystal panel 21. Thereby, the electric field is applied, the transmittance is adjusted, and an image corresponding to the pixel data PD is displayed. As a result, full color display is performed.

In the second write scan (data erase scan), the control signal CS of the control signal generation circuit 31 is used.
Outputs inverted pixel data #PD from the selector 37,
A signal of a voltage corresponding to the reverse pixel data #PD output from the selector 37 is transmitted from the data driver 32 to the liquid crystal panel 21.
Are supplied to each pixel. As a result, an electric field having the same strength as the electric field applied to each pixel at the time of the first writing scan and having the opposite polarity is applied to each pixel of the liquid crystal panel 21. Thereby, the display of each pixel of the liquid crystal panel 21 is erased.

First write scan (data write scan)
Since the voltage of the signal supplied to each pixel of the liquid crystal panel 21 has the same magnitude and a different polarity only in the second writing scan (data erasing scan), the application of the DC component to the liquid crystal is prevented. .

In the above example, only the red emission time is different from the green and blue emission times. However, the green or blue emission time may be different from other colors. Red,
It goes without saying that all the light emission times of green and blue may be different times.

FIG. 6 is a time chart for explaining the principle of the second embodiment of the display control method of the liquid crystal display device according to the present invention. FIG.
FIG. 6B shows the light emission timing of the ED, and FIG.
21 shows the scanning timing of each line.

In the above-described first embodiment shown in FIG. 5, the light is emitted continuously in the order of red, green, and blue.
In the embodiment of the present invention, the light emission time of each of the red,
Light emission is performed in the order of green and blue, but a pause period during which no light is emitted is provided between red and green, green and blue, and blue and red. In addition,
The scanning method of the liquid crystal panel 21 for performing two writing scans (data writing scan and data erasure scanning) in one subframe is the same as that of the first embodiment, and therefore the description thereof is omitted.

In the conventional liquid crystal display device, the red, green, and blue LEDs have the same light emission time, and the red, green, and blue LEDs have the same light emission time.
When the number of EDs is the same, the emission intensity of the red LED is lower than the emission intensity of the other green and blue LEDs, so the white display is considered to be bluish green. Therefore, in the conventional liquid crystal display device, the number of red LEDs is made larger than the number of green and blue LEDs to compensate for the low light emission intensity of the red LEDs, which causes an increase in cost.

On the other hand, in the liquid crystal display device of the present invention, the emission times of the red, green, and blue LEDs are not the same, and
Each light emission time is adjusted according to each light emission intensity of each of the red, green, and blue LEDs. Therefore, good white display can be achieved without increasing the number of red LEDs having low light emission intensity.

Next, specific embodiments of the liquid crystal display device and the display control method of the present invention will be described.

Example 1 First, the liquid crystal panel 21 shown in FIGS. 2 and 3 was manufactured as follows. Each pixel electrode 40 has a pitch of 0.24 mm x 0.24 mm and the number of pixels is 1024 x 768.
An FT substrate was manufactured. After washing such a TFT substrate and the glass substrate 2 having the common electrode 3, polyimide is applied by a spin coater and baked at 200 ° C. for 1 hour to form polyimide films of about 200 ° as alignment films 11 and 12. Filmed. Further, these alignment films 11 and 12 were rubbed with a cloth made of rayon, and overlapped with a gap maintained by a spacer 14 made of silica having an average particle diameter of 1.6 μm between them, thereby producing an empty panel. A liquid crystal layer 13 was formed by filling a ferroelectric liquid crystal containing a naphthalene-based liquid crystal as a main component between the alignment films 11 and 12 of the empty panel.

Then, the produced panel is used as two polarizing films in a crossed Nicols state (Nitto Denko: NPF-EG1225DU).
The liquid crystal panel 21 was sandwiched so that the ferroelectric liquid crystal molecules of the liquid crystal layer 13 would be in a dark state when tilted to one side. Then, the liquid crystal panel 21 and a backlight 22 capable of time-division light emission of red, green, and blue were overlapped. The number of each of the red, green, and blue LEDs in the LED array 7 is assumed to be 80, and these are referred to as a light guide plate + a light diffusion plate 6.
Was disposed on the light guide plate side.

The backlight 22 has a drive current of about 20 m.
FIG. 7 shows the white display and the chromaticity of the red, green, and blue display when the light emission times of A, red, green, and blue are all driven at about 5.56 ms. From FIG. 7, it can be seen that, with respect to red, green, and blue displays, a display with high color purity is obtained, but the white display has a bluish green tint. This is because the light emission intensity per red LED is smaller than the light emission luminance per green and blue LED, and the balance between green and blue is poor.

Next, display was performed by setting the drive current to about 20 mA, and as shown in FIG. 5, the red light emission time to about 8.33 ms, and the green and blue light emission times to about 4.17 ms. FIG. 8 shows the white display and the chromaticities of the red, green, and blue displays in this case. FIG.
From this, it can be seen that red, green, and blue displays showing high color purity and white display close to the C light source were obtained. As described above, in the present invention, good white display can be realized without increasing the light emission intensity by adjusting the light emission time of red, green, and blue, not the same, according to the light emission intensity.

(Comparative Example 1) A liquid crystal panel 21 manufactured in exactly the same manner as in Example 1 described above was overlaid with a backlight 22 capable of time-division light emission of red, green and blue. Note that LE
The number of red, green, and blue LEDs in the D array 7 is 160 for red and 80 for green and blue, respectively.
It was arranged on the light guide plate side of the light diffusion plate 6.

The driving current of the backlight 22 is about 20 m.
FIG. 9 shows the white display and the chromaticities of the red, green, and blue displays when the light emission times of A, red, green, and blue are all driven at about 5.56 ms. From FIG. 9, it can be seen that red, green, and blue displays showing high color purity and white display close to the c light source are obtained.

In Comparative Example 1, a good display color can be obtained by setting the number of red LEDs to twice the number of green and blue LEDs. However, the number of LEDs is greatly increased, and the cost is high. In addition, there is no room for arranging these many LEDs on the light guide plate side, and there is a problem in terms of installation of LEDs and heat exhaustion.

(Embodiment 2) A liquid crystal panel 21 manufactured in exactly the same manner as in the above-mentioned embodiment 1 and a backlight 22 capable of time-division light emission of red, green and blue were superposed. Note that LE
The number of each of the red, green, and blue LEDs in the D array 7 was 80, and these were arranged on the light guide plate side of the light guide plate + light diffusion plate 6.

Then, the driving current was set to about 20 mA, and as shown in FIG. 5, the display was performed with the red emission time set to about 8.33 ms and the green and blue emission times set to about 4.17 ms. Using the white display in this case as a reference, the chromaticity of the white display when the drive current was changed within the range of about 0.25 to 1.5 times was examined while the respective light emission times were fixed. The result is shown in FIG. The numerical values in FIG. 10 are the ratio of the drive current to the reference. FIG. 10 shows that the color balance can be adjusted by adjusting the drive current of the LED.

(Embodiment 3) A liquid crystal panel 21 manufactured in exactly the same manner as in the above-mentioned embodiment 1 and a backlight 22 capable of time-division light emission of red, green and blue were superposed. Note that LE
The number of each of the red, green, and blue LEDs in the D array 7 was 80, and these were arranged on the light guide plate side of the light guide plate + light diffusion plate 6.

Then, the driving current was set to about 20 mA, and as shown in FIG. 5, the display was performed with the red light emission time set to about 8.33 ms and the green and blue light emission times set to about 4.17 ms. Based on the white display in this case, the chromaticity of the white display was examined when the drive current was fixed at 20 mA and the respective light emission times were changed within a range of about 0.5 to 1.0 times. The result is shown in FIG. Figure
The numerical value in 11 is the ratio of the light emission time to the reference. FIG. 11 shows that the color balance can be adjusted by adjusting the light emission time of the LED.

(Embodiment 4) A liquid crystal panel 21 manufactured in exactly the same manner as in the above-mentioned Embodiment 1 and a backlight 22 capable of time-division light emission of red, green and blue were superposed. Note that LE
The number of each of the red, green, and blue LEDs in the D array 7 was 80, and these were arranged on the light guide plate side of the light guide plate + light diffusion plate 6.

Then, the driving current was set to about 20 mA, and as shown in FIG. 5, display was performed with the red light emission time set to about 8.33 ms and the green and blue light emission times set to about 4.17 ms. Based on the white display in this case, the drive current is changed within a range of about 0.25 to 1.5 times, and each light emission time is set to about 0.5 to 1.
The chromaticity of white display when changed within the range of 0 times was examined. The result is shown in FIG. The numerical value in FIG. 12 is the product of the ratio of the drive current to the reference and the ratio of the light emission time to the reference. From FIG. 12, it can be seen that by adjusting both the LED drive current and the light emission time, it is possible to adjust the color balance over a wider chromaticity range than when only one of them is made variable. .

In the above embodiment, the liquid crystal material is
Although a ferroelectric liquid crystal is used, a similar effect can be obtained by using a liquid crystal other than a ferroelectric liquid crystal, for example, an antiferroelectric liquid crystal.

[0064]

As described above, in the present invention, the light emission time of each of the red, green, and blue light sources is not the same, but is variable.
Even when the green and blue light sources are not balanced in intensity, the display color at the time of mixing can be adjusted by controlling the emission time of each emission color. In addition, since one or both of the light emission time and the light emission intensity are made variable, the color balance can be adjusted, and a display with excellent display colors can be made.

[Brief description of the drawings]

FIG. 1 is a block diagram of an overall example of a liquid crystal display device of the present invention.

FIG. 2 is a schematic sectional view of a liquid crystal panel and a backlight used in the liquid crystal display device of the present invention.

FIG. 3 is a schematic diagram illustrating an example of the entire configuration of a liquid crystal display device of the present invention.

FIG. 4 is a schematic diagram illustrating a configuration example of an LED array.

FIG. 5 is a time chart for explaining the principle of the first embodiment of the display control method of the liquid crystal display device of the present invention.

FIG. 6 is a time chart for explaining the principle of the second embodiment of the display control method of the liquid crystal display device of the present invention.

FIG. 7 is a diagram showing display colors by a conventional liquid crystal display device.

FIG. 8 is a diagram showing display colors by the liquid crystal display device (Example 1) of the present invention.

FIG. 9 is a diagram showing display colors of a conventional liquid crystal display device (Comparative Example 1).

FIG. 10 is a diagram showing display colors by a liquid crystal display device (Example 2) of the present invention.

FIG. 11 is a diagram showing display colors by a liquid crystal display device (Example 3) of the present invention.

FIG. 12 is a diagram showing display colors by a liquid crystal display device (Example 4) of the present invention.

FIG. 13 is a time chart for explaining an example of a conventional display control method of a liquid crystal display device.

[Explanation of symbols]

 1,5 polarizing film 6 light guide plate + light diffusion plate 7 LED array 13 liquid crystal layer 21 liquid crystal panel 22 backlight 30 image memory 31 control signal generation circuit 32 data driver 33 scan driver 35 backlight control circuit and drive power supply 36 reverse data generation Circuit 37 Selector 40 Pixel electrode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Hiroki Shirato 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Prefecture Inside Fujitsu Limited (72) Tetsuya Makino 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa No. 1 Fujitsu Limited (72) Inventor Yoshinori Kiyota 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa F-term within Fujitsu Limited (reference) 2H093 NA43 NA53 NA65 NC16 NC29 NC34 NC44 ND17 ND24 ND34 ND54 NF19 NF20 NH15 5C006 AA22 AF52 BA12 BA13 BB16 EA01

Claims (6)

[Claims] 1. A switching element corresponding to each pixel of a liquid crystal panel is switched in a period of each display cycle corresponding to data of three colors of each pixel, and each display cycle is synchronized with the switching of the switching element. A display control method for a liquid crystal display device that emits three-color light of a backlight in a time-division manner during a period of time, wherein at least two of the emission times of the three-color light of the backlight are made different. Display control method. 2. The display control method for a liquid crystal display device according to claim 1, wherein the light emission time and / or the light emission intensity of each of the three color lights of the backlight is variable. 3. The display control method for a liquid crystal display device according to claim 1, wherein a total of light emission times of the three colors of light of the backlight is 1/60 second or less. 4. A liquid crystal panel having a plurality of liquid crystal pixels and a plurality of switching elements provided corresponding to each of the liquid crystal pixels, a backlight disposed on the back of the liquid crystal panel, and emitting three-color light, In a liquid crystal display device comprising: a driving unit for switching a switching element in accordance with data of three colors of each of the liquid crystal pixels, the backlight of three colors emits time-division light with at least two different emission times. A liquid crystal display device comprising backlight control means. 5. The backlight includes an LED that emits light of each of three colors, a diffusion plate that diffuses light emitted by the LED, and a light guide plate that guides light emitted by the LED to one surface of the liquid crystal panel. The liquid crystal display device according to claim 4, comprising: 6. The liquid crystal display device according to claim 4, wherein the liquid crystal material of the liquid crystal panel is a ferroelectric liquid crystal material or an antiferroelectric liquid crystal material.