JP2002372953A - Field sequential color liquid crystal display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate color dispersion within a product and an individual difference among the products by displaying the same color at all times regardless of the dispersion of the wavelength of a light emitting element in a field sequential color liquid crystal display. SOLUTION: The LEDs of three colors which are red, green and blue are provided behind an LCD, and by successively lighting red, green and blue LEDs at a high speed for a prescribed time when the LCD is open, the three colors are mixed on a time base and recognized as a desired color. In this case, in order to be recognized as blue at a point 2 on a chromaticity diagram 1 no matter what blue light emitting element B is used as long as it is the blue LED, by slightly lighting the red LED and the green LED as well when the blue LED is lighted, sliding from the chromaticity range of the blue light emitting element B to an inner side is performed and matching with the point 2 is performed. Similarly, also for the red LED and the green LED, the other two colors are slightly lighted simultaneously and matching with the point 3 and the point 4 is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field-sequential (hereinafter, also referred to as "FS type") color liquid crystal display device, and more particularly to variations in display colors based on wavelength variations of light emitting elements. The present invention relates to an FS type color liquid crystal display device which can solve the problem.
In this specification, the LED chip itself is referred to as a “light emitting element”, and the entire light emitting device on which the LED chip is mounted is referred to as a “light emitting diode” or “LED”.

[0002]

2. Description of the Related Art In order to develop a low-cost color liquid crystal display, a field sequential type color liquid crystal display device of a type different from a conventional color filter type liquid crystal panel has been developed. This FS type color liquid crystal display device
The three primary colors of light, red, green, and blue, are displayed one after another from a one-dot liquid crystal window, and by switching these at high speed, various colors are mixed and displayed in a time-division manner. The light imaged on the retina enters the photoreceptor cells, and the light stimulus at the photoreceptor cells is transmitted to brain cells as an electrical signal via a chemical reaction. If the display of red, green, and blue is switched at a sufficiently high speed with respect to the series of reaction speeds, the three colors are perceived as mixed colors.
As a three-color backlight light source of the FS type color liquid crystal display device, an LED has attracted attention.

[0003]

However, when an LED is used as a three-color backlight source of an FS type color liquid crystal display device, the red, green and blue light-emitting elements of the three primary colors of light have variations in emission wavelength during the manufacturing stage. Occurs, and FS is caused by the LED using the light emitting element having the wavelength variation.
In the case of displaying by the method, color variation occurs in each single color or white. Although the luminous intensity can be adjusted, it could not be adjusted because the wavelength was determined at the manufacturing stage.

Accordingly, the present invention provides an FS type color liquid crystal display device in which the same color is always displayed irrespective of the variation in the wavelength of the light emitting element, thereby eliminating the variation in the color in the product and the individual difference between the products. The task is to provide.

[0005]

According to a first aspect of the present invention, there is provided an FS type color liquid crystal display device, wherein one of the three primary colors of light is turned on in the liquid crystal display device.
At the same time, at least one of the other two colors is turned on for color correction so that the one color always displays the same point on the chromaticity diagram.

Thus, for example, when a red LED is turned on in a liquid crystal display device, a green LED
By slightly turning on the blue LED, the displayed red color is corrected to one point from the inside of a predetermined red area of the chromaticity diagram. Thereby, even when the red LED using the red light emitting element having a different wavelength is turned on, the green LED and the blue LED are also slightly turned on at the same time, so that one point from the inside of the predetermined red area of the chromaticity diagram is obtained. Can be corrected for all red. In this way, the green LED and the blue LED are slightly turned on in accordance with the degree of the difference in the red color, whereby the red LE
The variation in wavelength in the stage of manufacturing the red light emitting element D is absorbed, so that one point from the inside of a predetermined red area of the chromaticity diagram is displayed for all red.

As a result, the same red color is displayed within the product of the FS type color liquid crystal display device and between the devices without variation. The above results are obtained in the same manner for the green LED and the blue LED. Further, by performing this between devices, an FS type color liquid crystal display device having no individual difference can be produced.

In this way, the same color can always be displayed irrespective of the variation in the wavelength of the light emitting element, so that the FS type color liquid crystal display device has no variation in the color in the product and no individual difference between the products. .

According to a second aspect of the present invention, in the FS type color liquid crystal display device according to the first aspect of the present invention, at least one of the other two colors of LEDs is turned on for color correction by a lighting time. The length is adjusted.

In the method of the present invention in which one color LED is turned on and the other two colors are turned on for color correction, the colors of the light emitting elements having wavelength variations are shifted inward in the chromaticity diagram. Therefore, even if the LED has a light emitting element of any wavelength, the correction ratio is adjusted to one point on the chromaticity diagram, so that the lighting ratio of the other two colors of the LED may be small. Here, as a method of slightly turning on the other two-color LEDs, there is a method of turning on the liquid crystal for a part of the whole time during which the liquid crystal is opened and the one-color LED is turned on. By adjusting the ratio of the partial time to the total time for each LED, any LED having a light emitting element of any wavelength can be adjusted to one point on the chromaticity diagram. The method of adjusting the pulse length in this way is as follows.
There is an advantage that the circuit configuration is simplified and fine adjustment is easy.

According to a third aspect of the present invention, in the FS type color liquid crystal display device according to the first aspect of the present invention, a ratio of a current for energizing an LED of at least one of the other two colors for color correction is determined. The size is adjusted.

In other words, as a method of slightly lighting the other two-color LEDs, instead of turning on the liquid crystal all the time while the one-color LED is on, the current flowing through the other two-color LEDs is reduced. This is a method of lighting with much less light intensity by adjusting. According to this method, it is easy to understand how much the luminous intensity should be reduced, and even when the pulse width of the main color changes, the other two colors may be changed to the same pulse width accordingly. Therefore, there is an advantage that it is technically easy.

According to a fourth aspect of the present invention, in the FS type color liquid crystal display device according to any one of the first to third aspects, the display color gamut of the three primary colors of the light, which appears to be mixed by time division, is always adjusted. Control is performed within the same range in the chromaticity diagram.

Therefore, since the display color gamut is the same between products, the color tone does not look different for each product regardless of what color is displayed by each dot, and the FS type color liquid crystal has no individual difference. Display devices can be produced.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

First Embodiment First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic diagram showing a concept of a field sequential color liquid crystal display device according to a first embodiment of the present invention on a chromaticity diagram. FIG. 2 is a chart showing a color adjusting method in the field sequential color liquid crystal display device according to the first embodiment of the present invention.

In the FS type color liquid crystal display device according to the first embodiment, LEDs of three primary colors of light, red, green and blue, are provided behind the liquid crystal (LCD). When the liquid crystal is open, the red, green, and blue LE
By lighting D one after another at high speed for a predetermined time, 3
The colors mix on the time axis and are perceived as the desired color. Here, as shown in the chromaticity diagram of FIG. 1, the red light emitting element R, the green light emitting element G, and the blue light emitting element B used for the red, green, and blue LEDs have emission wavelengths at the time of manufacture. As shown in the figure, since the colors vary within a certain range, if they are used as they are, they will not be recognized as the desired colors, but will be recognized as different colors for each device, and color unevenness will occur. So, blue LED
No matter what blue light emitting element B is used, chromaticity diagram 1
As it is recognized as the blue color of point 2 above, the red LED and the green LED are slightly lit when the blue LED is lit, thereby sliding inward from the chromaticity range of the blue light emitting element B, Try to match point 2.

Similarly, for the red LED, the blue LED
And green LED at the same time,
Slide inward from the chromaticity range of the red light emitting element R,
Try to match point 3. Further, similarly, for the green LED, the blue LED and the red LED are slightly lit at the same time, so that the green LED G is slid inward from the chromaticity range of the green light emitting element G so as to match the point 4. As described above, in the FS type color liquid crystal display device of the first embodiment, since blue is displayed at point 2, red is displayed at point 3, and green is displayed at point 4, color unevenness is displayed over the entire screen. No color is generated and an excellent color liquid crystal display device is obtained.

Furthermore, the range of colors displayed by mixing these three colors in the FS system is also limited to the triangle 5 formed by connecting the points 2, 3, and 4. It is possible to produce a color liquid crystal display device having no color shift and no individual difference.

Next, a specific method for eliminating the color unevenness of the red light emitting element R, the green light emitting element G, and the blue light emitting element B in the FS type color liquid crystal display device of the first embodiment will be described with reference to FIG. explain. The LED is turned on when the liquid crystal (LCD) is open. As shown in FIG. 2, there is a time lag from when the LCD starts to open until the LCD is fully opened, so that the opening of the LCD has a gentle rise. When this LCD opens, first red LED
Lights up, but a little later, green LED, blue LE
D also turns on and turns off in a short time. Thereby, the red color of the red light emitting element R used for the red LED is shifted inward on the chromaticity diagram, and is displayed in red corresponding to the point 3 in FIG.

When the red LED is turned off and the LCD is closed,
Next, when the LCD is opened, the green LED is turned on next.
The red LED and the blue LED are also turned on with a short delay, and are turned off in a short time. As a result, the green color of the green light emitting element G used for the green LED is shifted inward on the chromaticity diagram, and is displayed in green corresponding to the point 4 in FIG. Green LE
When D is turned off and the LCD is closed, the next time the LCD is opened, the blue LED is turned on. Red LED with a little delay
The green LED also turns on and turns off in a short time. Thereby, the blue color of the blue light emitting element B used for the blue LED is shifted inward on the chromaticity diagram, and is displayed in blue corresponding to the point 2 in FIG.

As described above, in the FS type color liquid crystal display device of the first embodiment, the chromaticity of the main color is adjusted by adjusting the duty ratio of the other two colors to be lit for color correction. It is shifted inward so that colors corresponding to the predetermined points 2, 3, and 4 are displayed.

When the pulse width of the LED of the main color changes, the LEs of the other two colors which are naturally turned on for color correction
The pulse width of D also changes accordingly. Note that FIG. 2 shows a case where the pulse widths of the LEDs of the other two colors that are lit for color correction are the same, but the L of the other two colors is the same.
The pulse widths of the EDs may be different from each other.

Second Embodiment Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a chart showing a color adjusting method in the field sequential color liquid crystal display device according to the second embodiment of the present invention.

As shown in FIG. 3, this liquid crystal (LC
The LED is lit when D) is open. As in the first embodiment, there is a time lag from when the LCD starts to open until the LCD is fully opened, so that the opening portion of the LCD has a gentle rise. When this LCD is opened, first the red LED is turned on, but at the same time, the green LED is turned on.
The ED and blue LEDs also light with much less current than the red LEDs. As a result, the red color of the red light emitting element R used for the red LED is shifted inward on the chromaticity diagram,
It is displayed in red corresponding to point 3 in FIG. Red LED,
The LCD closes after the green LED and the blue LED turn off.

Next, when the LCD is opened, the green LED is turned on, and at the same time, the red and blue LEDs are also turned on with much less current than the green LED. By this, green LED
The green color of the green light emitting element G used in the above is shifted inward on the chromaticity diagram, and is displayed in green corresponding to the point 4 in FIG. The LCD closes after the red, green, and blue LEDs have turned off. Next, when the LCD is opened, the blue LED is turned on, and at the same time, the red and green LEDs are also turned on with much less current than the blue LED. Thereby, the blue L
The blue color of the blue light emitting element B used in the ED is shifted inward on the chromaticity diagram, and is displayed in blue corresponding to the point 2 in FIG.

As described above, in the FS type color liquid crystal display device according to the second embodiment, the chromaticity of the main color is adjusted by adjusting the currents of the other two colors to be lit for color correction. To the predetermined points 2, 3,
4 are adjusted so that colors corresponding to the respective colors are displayed.

When the pulse width of the LED of the main color changes, the LEs of the other two colors which are naturally turned on for color correction are changed.
The pulse width of D also changes to the same pulse width. FIG. 3 shows a case where the currents of the other two colors of LEDs that are lit for color correction are the same, but the other two colors of LEs
The currents of D may be different from each other.

The configuration, shape, quantity, material, size, connection relationship, and the like of the other parts of the field sequential type color liquid crystal display device are not limited to the above embodiments.

[0030]

As described above, in the FS type color liquid crystal display device according to the first aspect of the present invention, when one of the three primary color LEDs of the light is turned on in the liquid crystal display device, the other color is simultaneously displayed. By illuminating at least one LED of the two colors for color correction, the one color is corrected so as to always display the same point on the chromaticity diagram.

Thus, for example, when the red LED is turned on in the liquid crystal display device, the green LED
By slightly turning on the blue LED, the displayed red color is corrected to one point from the inside of a predetermined red area of the chromaticity diagram. Thereby, even when the red LED using the red light emitting element having a different wavelength is turned on, the green LED and the blue LED are also slightly turned on at the same time, so that one point from the inside of the predetermined red area of the chromaticity diagram is obtained. Can be corrected for all red. In this way, the green LED and the blue LED are slightly turned on in accordance with the degree of the difference in the red color, whereby the red LE
The variation in wavelength in the stage of manufacturing the red light emitting element D is absorbed, so that one point from the inside of a predetermined red area of the chromaticity diagram is displayed for all red.

As a result, the same red color is displayed within the product of the FS type color liquid crystal display device and between the devices without variation. The above results are obtained in the same manner for the green LED and the blue LED. Further, by performing this between devices, an FS type color liquid crystal display device having no individual difference can be produced.

In this way, the same color can always be displayed irrespective of the variation in the wavelength of the light emitting element, so that the FS type color liquid crystal display device has no color variation in the product and individual differences between the products. .

According to a second aspect of the present invention, in the FS type color liquid crystal display device according to the first aspect of the present invention, at least one of the other two colors of the LED is turned on for color correction. The length is adjusted.

According to the method of the present invention in which one color LED is turned on and the other two colors are turned on for color correction, the colors of the light emitting elements having wavelength variations are shifted inward in the chromaticity diagram. Therefore, even if the LED has a light emitting element of any wavelength, the correction ratio is adjusted to one point on the chromaticity diagram, so that the lighting ratio of the other two colors of the LED may be small. Here, as a method of slightly turning on the other two-color LEDs, there is a method of turning on the liquid crystal for a part of the whole time during which the liquid crystal is opened and the one-color LED is turned on. In addition to the effects described in claim 1, by adjusting the ratio of this partial time to the total time for each LED, any LED having a light emitting element of any wavelength can be displayed on the chromaticity diagram. Can be adjusted to one point. The method of adjusting the pulse length in this manner has an advantage that the circuit configuration is simple and fine adjustment is easy.

According to a third aspect of the present invention, in the FS type color liquid crystal display device according to the first aspect of the present invention, a ratio of a current for energizing at least one LED of the other two colors for color correction. The size is adjusted.

That is, in addition to the effect of the first aspect, as a method of slightly lighting the other two-color LEDs, instead of turning on the liquid crystal for the entire time when the one-color LED is turned on, This is a method in which the current flowing through the other two colors of LEDs is finely adjusted and the LED is turned on with much less luminous intensity. According to this method, it is easy to understand how much the luminous intensity should be reduced, and even when the pulse width of the main color changes, the other two colors may be changed to the same pulse width accordingly. Therefore, there is an advantage that it is technically easy.

According to a fourth aspect of the present invention, in the FS type color liquid crystal display device according to any one of the first to third aspects, the display color gamut of the three primary colors of the light, which appears to be mixed by time division, is always adjusted. Control is performed within the same range in the chromaticity diagram.

Therefore, in addition to the effects described in any one of claims 1 to 3, since the display color gamut is the same between products, the product can be used regardless of the color displayed by each dot. It is possible to produce an FS type color liquid crystal display device that does not look different from one color to another and has no individual difference.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a concept of a field sequential color liquid crystal display device according to a first embodiment of the present invention on a chromaticity diagram.

FIG. 2 is a chart showing a color adjustment method in the field sequential color liquid crystal display device according to the first embodiment of the present invention.

FIG. 3 is a chart showing a color adjustment method in a field sequential color liquid crystal display device according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Chromaticity diagram 2,3,4 Same point on chromaticity diagram 5 Same range in chromaticity diagram R, G, B Three primary colors of light

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G09G 3/34 G09G 3/34 J H01L 33/00 H01L 33/00 K F term (reference) 2H091 FA45Z LA15 LA16 2H093 NA65 NC43 ND17 ND24 5C006 AA22 AF46 BB16 BB29 FA16 5C080 AA10 BB05 CC03 EE30 JJ04 JJ05 5F041 AA11 AA12 DA14 FF01

Claims (4)

[Claims] 1. A liquid crystal display device comprising LEs of three primary colors of light.
When one of the colors D is lit, at least one of the other two LEDs is lit for color correction at the same time so that the one color always displays the same point on the chromaticity diagram. A field-sequential type color liquid crystal display device characterized in that the correction is performed as follows. 2. An L of at least one of the other two colors.
2. The field sequential color liquid crystal display device according to claim 1, wherein a ratio of lighting of the ED for color correction is adjusted by a lighting time. 3. An L of at least one of the other two colors.
2. The field sequential type color liquid crystal display device according to claim 1, wherein a ratio of lighting of the ED for color correction is adjusted by a magnitude of a current to be supplied. 4. The color gamut according to claim 1, wherein a display color gamut of the three primary colors of the light which appears to be mixed by time division is always controlled to the same range in the chromaticity diagram.
4. A field sequential type color liquid crystal display device as described in (1).