JPH11212056A - Liquid crystal display device and method of controlling illumination of liquid crystal panel - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a liquid crystal display device capable of always displaying a color image of a predetermined hue without being affected by external light. When a display color of a color image on a liquid crystal display panel changes due to external light L0, an RGB signal corresponding to color image light transmitted from the liquid crystal display panel and output from a phototransistor changes. R
A control signal F including an offset signal and a gain signal of each color with respect to a display image in accordance with a change in the GB signal.
c is output and the control signal Fc is input to the RG
In response to a control signal Fc from the microcomputer 6 from the B driver 7, the color application voltages VR and V
G and VB are output and applied to the liquid crystal display panel 5, and a color image color-compensated by white balance is displayed on the liquid crystal display panel 5 in accordance with the change in the amount of external light. Also, a color image of a predetermined color is always displayed on the liquid crystal display panel 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display and a method for controlling illumination of a liquid crystal panel of the liquid crystal display.

[0002]

2. Description of the Related Art Electronic equipment such as OA equipment and small portable telephones are equipped with a liquid crystal display device for displaying liquid crystal image information such as characters and figures. FIG. 4 is a block diagram showing the configuration of a conventional liquid crystal display device 15. A backlight 1 for irradiating illumination light to the liquid crystal display panel 5 is provided at the back of the liquid crystal display panel 5 for displaying image information such as text and graphics. A prism 3 is disposed between the backlight 1 and the liquid crystal display panel 5 so as to face the external light intake window 2. Further, the liquid crystal display device 15 is connected with an RGB driver 7 for supplying each color application voltage VR, VG, VB to the liquid crystal display panel 5, and the RGB driver 7 has a microcomputer for controlling a display operation of the liquid crystal display panel 5. 6 are connected.

As the liquid crystal display panel 5, a cholesteric liquid crystal cell and a DAP type cell are stacked, and light having a wavelength width △ λ centered on a specific wavelength λ0 selected by increasing or decreasing the helical pitch p based on the application of an electric field is selected. A scattered cholesteric liquid crystal display panel is used, and the backlight 1
Has a configuration in which a plurality of LEDs are arranged as light sources in a housing having a size corresponding to the entire surface of the liquid crystal display panel 5.

A conventional liquid crystal display device 15 having such a configuration is described.
When the drive signal Fd is input to the RGB driver 7 and the control signal Fc corresponding to the display image is input from the microcomputer 6, the RGB driver 7 outputs the color application voltages VR, VG, VB is output and applied to the liquid crystal display panel 5,
A color image is displayed. At this time, the liquid crystal display device 15
, External light L0 enters through an external light intake window 2, and the reflected light of the external light L0 from the prism 3 and the backlight light Lb from the backlight 1 passing through the prism 3 are illuminated. The light is superimposed as light and illuminates the liquid crystal display panel 5 from the back.

[0005]

When the conventional liquid crystal display device 15 described above is used outdoors, for example, on a day with strong sunlight, the amount of backlight Lb from the backlight 1 becomes larger than the amount of external light L0. And the color image displayed on the liquid crystal display panel 5 becomes extremely dark,
The hue of the color image displayed on the liquid crystal display panel 5 changes depending on the external light L0.

SUMMARY OF THE INVENTION The present invention has been made in view of the present situation of such a liquid crystal display device as described above. A first object of the present invention is to provide a color image having a predetermined color tone without being affected by external light. To provide a liquid crystal display device capable of displaying the same. A second object of the present invention is to provide a lighting control method for a liquid crystal panel of a liquid crystal display device which can always display a color image of a predetermined color without being affected by external light.

[0007]

In order to achieve the first object, the present invention is a liquid crystal display device in which a liquid crystal display panel for displaying an image is illuminated from the back by external light and a backlight. RG of transmitted light of the liquid crystal display panel
It is characterized by comprising a light receiving means for receiving each of the B spectral signals, and a liquid crystal display control means for changing and controlling a control signal of the liquid crystal display panel based on light receiving data of the light receiving means.

In order to achieve the second object, the present invention relates to a method for controlling the illumination of a liquid crystal display panel for displaying an image on a liquid crystal display device, wherein the liquid crystal display panel is rearwardly illuminated by external light and a backlight. And the control signal of the liquid crystal display panel is changed and controlled based on the received light data of the RGB spectral signal of the transmitted light of the liquid crystal display panel.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram showing a configuration of the present embodiment, and FIG. 3 is an explanatory diagram of a state of attachment of a light receiving element to a liquid crystal display panel of each embodiment.

In the present embodiment, as shown in FIG. 1, a phototransistor 10 for receiving color image light transmitted through the liquid crystal display panel 5 is mounted on the surface of the liquid crystal display panel 5. The output terminal is connected to the microcomputer 6. In the present embodiment, the microcomputer 6 displays an image of a predetermined color from the RGB driver 7 based on the RGB signal corresponding to the color image light transmitted through the liquid crystal display panel 5 and output from the phototransistor 10. It has a function of outputting a control signal Fc for outputting the color application voltages VR, VG, VB. The configuration of the other portions of the present embodiment is the same as that of the conventional liquid crystal display device described with reference to FIG. 4, and therefore, will not be described repeatedly.

The operation of this embodiment having such a configuration will be described. In the present embodiment, similarly to the conventional liquid crystal display device, when the drive signal Fd is input to the RGB driver 7 and the control signal Fc is input from the microcomputer 6, the RGB
The B driver 7 outputs color application voltages VR, VG, and VB for displaying an image of a predetermined color on the liquid crystal display panel 5, applies the voltage to the liquid crystal display panel 5, and outputs the predetermined color to the liquid crystal display panel 5. Is displayed. Then, external light L0 enters the liquid crystal display device 15A through the external light intake window 2, and the reflected light of the external light L0 at the prism 3 and the backlight Lb from the backlight 1 are The liquid crystal display panel 5 is superimposed as illumination light and illuminates the liquid crystal display panel 5 from the back.

In this case, in this embodiment, for example, when used outdoors, the amount of external light L0 increases, the luminous intensity of the illumination light increases, and the color image displayed on the liquid crystal display panel 5 becomes extremely large. When the color becomes dark and the hue of the color image displayed on the liquid crystal display panel 5 changes due to the external light L0,
The RGB signal corresponding to the color image light output from the phototransistor 10 and transmitted through the liquid crystal display panel 5 changes. The microcomputer 6 outputs a control signal Fc composed of an offset signal and a gain signal of each color for displaying an image of a predetermined color in accordance with the change of the RGB signal, and the control signal Fc is output to the RGB driver 7. Is input to

The RGB driver 7 outputs color application voltages VR, VG, VB for displaying an image of a predetermined color in response to a control signal Fc from the microcomputer 6, and outputs the color application voltages VR, VG. , VB are applied to the liquid crystal display panel 5, and in accordance with the change in the amount of the external light L0, a color image of a predetermined hue color-compensated by white balance is displayed on the liquid crystal display panel 5, and the change in the amount of external light L0 Even if it occurs, the liquid crystal display panel 5 always displays a color image of a predetermined color.

As described above, according to the present embodiment, the color image light transmitted through the liquid crystal display panel 5 is received by the phototransistor 10, and the change in the color tone of the color image due to the change in the amount of external light L0 is detected. Then, a control signal Fc for compensating for the change in the color to make the color of the display image a predetermined color is input to the RGB driver 7. And
The color application voltage VR corresponding to the control signal Fc,
Since VG and VB are output from the RGB driver 7 and applied to the liquid crystal display panel 5, it is possible to always display a color image of a predetermined color on the liquid crystal display panel 5.

[Second Embodiment] A second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the present embodiment.

In this embodiment, as shown in FIG. 2, a backlight controller 8 for controlling the amount of backlight Lb of the backlight 1 is provided, and an output terminal of the backlight controller 8 is connected to the backlight 1. It is connected. Then, in the present embodiment, the microcomputer 6
It has a function of outputting a light amount control signal Flc to the backlight controller 8 based on RGB signals corresponding to color image light transmitted from the phototransistor 10 and transmitted through the liquid crystal display panel 5. The configuration of other parts of the present embodiment is the same as that of the first embodiment already described with reference to FIG. 1, and therefore, will not be described repeatedly.

The operation of this embodiment having such a configuration will be described. In the present embodiment, similarly to the first embodiment, when the drive signal Fd is input to the RGB driver 7 and the control signal Fc is input from the
The B driver 7 outputs color application voltages VR, VG, and VB for displaying an image of a predetermined color, is applied to the liquid crystal display panel 5, and a color image of a predetermined color is displayed on the liquid crystal display panel 5. Is done. Then, external light L0 enters the liquid crystal display device 15B through the external light intake window 2, and the reflected light of the external light L0 at the prism 3 and the backlight from the backlight 1 passing through the prism 3. The light Lb is superimposed as illumination light and illuminates the liquid crystal display panel 5 from the back.

In this case, in the present embodiment, for example, when used outdoors, the amount of external light L0 increases, the luminous intensity of the illumination light increases, and the color image displayed on the liquid crystal display panel 5 becomes extremely large. When the color becomes dark and the hue of the color image displayed on the liquid crystal display panel 5 changes due to the external light L0,
The RGB signal corresponding to the color image light output from the phototransistor 10 and transmitted through the liquid crystal display panel 5 changes. Then, the microcomputer 6 responds to the change of the RGB signals by outputting a control signal F including an offset signal and a gain signal of each color for displaying an image of a predetermined color.
c is output, and the control signal Fc is input to the RGB driver 7.

At the same time, in the present embodiment, the microcomputer 6 outputs a light quantity control signal Flc in response to a change in the RGB signal corresponding to the color image light transmitted from the phototransistor 10 and transmitted through the liquid crystal display panel 5, and
This light amount control signal Flc is input to the backlight controller 8. Then, the backlight controller 8 controls the light amount of the backlight 1 based on the light amount control signal Flc.

In this manner, the RGB driver 7 responds to the control signal Fc from the microcomputer 6
Color application voltages VR and V for displaying an image of a predetermined color
G, VB are output, and the color application voltages VR, VG, VB
Is applied to the liquid crystal display panel 5, and the liquid crystal display panel 5 displays a color image of a predetermined hue color-compensated by white balance according to the change in the amount of external light. Even if it occurs, a color image of a predetermined color is always displayed on the liquid crystal display panel 5. At the same time, in the present embodiment, in response to a change in the RGB signal corresponding to the color image light transmitted through the liquid crystal display panel 5, based on the light amount control signal Flc output from the microcomputer 6,
The backlight controller 8 controls the amount of light of the backlight 1 to an optimum value.

As described above, according to the present embodiment, the color image light transmitted through the liquid crystal display panel 5 is received by the phototransistor 10, and the change in the color tone of the color image due to the change in the amount of external light L0 is detected. A control signal Fc for compensating for the change in the color to make the color of the display image a predetermined color is input to the RGB driver 7, and the color application voltages VR, VG, and VB corresponding to the control signal Fc.
Is output from the RGB driver 7 and the liquid crystal display panel 5
At the same time, the amount of the backlight light Lb of the backlight 1 is set to an optimum value according to the change of the RGB signal corresponding to the color image light detected by the phototransistor 10. For this reason, according to the present embodiment, the external light L
0, it is possible to always display a color image of a predetermined hue on the liquid crystal display panel 5 without being affected by the light amount change of 0, and the light amount of the backlight 1 is changed in accordance with the light amount change of the external light L0. It is set to an optimal value, and it is also possible to prevent useless power consumption.

The present invention is not limited to the above-described embodiment. For example, as shown in FIG. 3 (b), the present invention can be applied to the first embodiment or the second embodiment. The phototransistor 1 inside the liquid crystal display panel 5.
It is also possible to arrange 0.

[0023]

According to the first aspect of the present invention, the liquid crystal display panel for displaying an image of the liquid crystal display device is illuminated from the back by the external light and the backlight, and the light receiving means RGB of the transmitted light of the liquid crystal display panel. Each of the spectral signals is received, and the liquid crystal display control means controls the liquid crystal display panel control signal in accordance with the level of the RGB spectral signal of the transmitted light based on the received light data of the light receiving means. The white balance is constantly adjusted according to the change in the amount of light with the light, and the color of the transmitted light of the liquid crystal display panel can be kept constant and the image of the predetermined color can always be displayed on the liquid crystal display panel. .

According to the second aspect of the invention, in addition to the effect obtained by the first aspect of the invention, the amount of light of the backlight is controlled by the backlight control means based on the light reception data of the light receiving means. RGB of transmitted light
It is possible to set an optimal amount of light for the backlight according to the level of the spectral signal, thereby preventing unnecessary power consumption.

According to the third aspect of the invention, the liquid crystal display panel for displaying an image of the liquid crystal display device is illuminated from the back by the external light and the backlight, and the received light data of the RGB spectral signal of the transmitted light of the liquid crystal display panel. , The control signal of the liquid crystal display panel is changed and controlled according to the level of the RGB spectral signal of the transmitted light, so that the white balance is always adjusted according to the change in the amount of light between the outside light and the backlight. In addition, it is possible to maintain the color of the transmitted light of the liquid crystal display panel constant, and to always display an image of a predetermined color on the liquid crystal display panel.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a first exemplary embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a second exemplary embodiment of the present invention.

FIG. 3 is an explanatory diagram of a mounting state of a light receiving element to a liquid crystal display panel according to each embodiment of the present invention.

FIG. 4 is a block diagram illustrating a configuration of a conventional liquid crystal display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Back light, 2 ... External light intake window, 3 ... Prism, 5
... Liquid crystal display panel, 6 ... Microcomputer, 7 ... RGB driver, 8 ... Backlight controller, 10 ... Phototransistor, 15A, 15B ... Liquid crystal display device

Claims (3)

[Claims] 1. A liquid crystal display device in which a liquid crystal display panel for displaying an image by external light and a backlight is illuminated from the back, and light receiving means for receiving RGB spectral signals of light transmitted through the liquid crystal display panel, respectively. And a liquid crystal display control means for changing and controlling a control signal of the liquid crystal display panel based on light reception data of the light receiving means. 2. The liquid crystal display device according to claim 1,
A liquid crystal display device comprising a backlight control means for controlling the amount of light of the backlight based on light reception data of the light receiving means. 3. An illumination control method for a liquid crystal display panel for displaying an image of a liquid crystal display device, wherein the liquid crystal display panel is illuminated from the back with external light and a backlight, and RGB of transmitted light of the liquid crystal display panel is provided. A lighting control method for a liquid crystal panel of a liquid crystal display device, wherein a control signal of the liquid crystal display panel is changed and controlled based on light reception data of a spectral signal.