JPH0981091A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of improving the reproducibility at the time of displaying an analog picture in the color liquid crystal display device of an ECB system. SOLUTION: In the color liquid crystal display device, when a video signal is inputted from a video device, only a luminance signal Va is extracted from the video signal in the video signal processing circuit 52a in a level shift characteristic correcting circuit 52 to be outputted to a level shifting circuit 52b and the voltage level of the luminance signal Va is shifted by the level equivalent to 2V1 in the level shifting circuit 52b. When the shifted luminance voltage signal Vb is outputted to a luminance voltage characteristic correcting circuit 52c, the shifted luminance voltage signal level Vb is subjected to a correction with polygonal line approximation according the voltage level of the shifted luminance voltage signal level Vb so that the relationship between the shifted luminance voltage signal level Vb and a luminance characteristic approaches a straight line based on the luminance-voltage characteristic curve of an ECB type LCD panel in the circuit 52c and then a corrected luminance signal Vc is generated to be outputted to a selection circuit.

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 device for displaying a color image, and more particularly to a liquid crystal display device for displaying an input image in color by utilizing the birefringence of liquid crystal.

[0002]

2. Description of the Related Art Conventionally, a liquid crystal display device has been known as a display device for a television, a personal computer, a wristwatch and the like, and in recent years, a chromatic display is performed like a liquid crystal color television or a color display of a computer terminal. Color liquid crystal display devices that can be used are also becoming popular.

In a color liquid crystal display device, in general,
The display is a transmissive type in which a liquid crystal cell is sandwiched between a pair of polarizing plates and a backlight (illumination light source) is arranged outside one polarizing plate. In that case, the liquid crystal cell is formed with a liquid crystal sandwiched between a pair of transparent electrodes facing each other, and a color filter that selectively transmits light of a specific wavelength is provided on the side of one of the transparent electrodes. .

Then, by turning on / off the drive voltage applied between the pair of transparent electrodes, the light of the backlight is transmitted / non-transmitted through the liquid crystal display body, and the light of the backlight is colored in the liquid crystal display body. When passing through the filter,
It is colored with a specific color that is selectively transmitted by the color filter. The colored transmitted light is emitted from the liquid crystal display, and a display colored with the color of the color filter is obtained.

That is, in the conventional liquid crystal display, the liquid crystal cell merely functions as an optical switch, and the coloring of light is performed by the color filter.

[0006]

However, since the color filter generally has a low light transmittance, the color liquid crystal display device using the above-mentioned conventional color filter tends to have a large light loss of the transmitted light and darken the display. is there.

In particular, in the case of a reflection type liquid crystal display device used for a simple display section such as a calculator or a watch which does not require a very fine display, it is not equipped with a dedicated light source (backlight) and color When the filter is provided, it is transmitted through the color filter twice before reflection and after reflection, and light loss occurs. Therefore, it is extremely difficult to colorize the reflection type color filter.

Further, the color filter, like other optical elements such as polarized light, requires high precision in dimensions such as thickness and its assembling, which causes an increase in cost of the liquid crystal display device.

Therefore, a polarizing plate is arranged directly or through a retardation plate on at least the surface of the liquid crystal cell in which a liquid crystal layer is interposed between a pair of opposing electrodes, on which light is incident. A liquid crystal display panel is provided, and the light transmitted through the liquid crystal layer is elliptically polarized by the birefringence effect of the liquid crystal, and the retardation of the liquid crystal layer is changed by changing the liquid crystal drive voltage applied to the liquid crystal layer. There is a liquid crystal display device that color-displays a liquid crystal display panel that changes the polarization state and changes the color of transmitted light based on input data, and is a reflective color liquid crystal display device without a color filter or a dedicated light source (backlight). Has been realized.

Such a color liquid crystal display device has an ECB
(Electrically Controlled Biref-ringence) system, for example, as shown in FIG. 12, digital image data input from a personal computer (PC) 1 or the like is converted into a voltage value by a data voltage / conversion circuit 2. Then, the voltage signal is applied to the ECB type LCD panel 3 to display the color of the input image data.

The inside of the data voltage / conversion circuit 2 of FIG. 12 has a color selection table 2a and a D / A as shown in FIG.
The digital image data (2 bits for each of R, G, and B), which is composed of the conversion circuit 2b, is converted into a color number value in the order of voltage level by the color selection table 2a, and the color number value is converted to the D / A conversion circuit 2b. To generate a drive voltage signal. FIG. 14 shows an example of the color selection table 2a.

However, in such a conventional ECB type liquid crystal display device, only the multi-color display in which the number of colors to be displayed is about 8 to 16 is possible, and when the input data is an analog image, the number of display colors is displayed. However, there was a problem that the reproducibility was not sufficient due to the small number.

An object of the present invention is to provide a liquid crystal display device which improves reproducibility when displaying an analog image in an ECB type color liquid crystal display device.

[0014]

According to another aspect of the present invention, there is provided a liquid crystal display device comprising: a liquid crystal cell having a liquid crystal layer interposed between a pair of electrodes facing each other; A liquid crystal drive panel which is provided with a liquid crystal display panel in which a polarizing plate is arranged directly or via a retardation plate, the light transmitted through the liquid crystal layer is elliptically polarized by the birefringence action of the liquid crystal, and applied to the liquid crystal layer. By changing the retardation of the liquid crystal layer by changing the, the liquid crystal display panel for color display based on the input data liquid crystal display panel that changes the polarization state of the elliptically polarized light to change the color of the transmitted light, the input data is In the case of an analog image signal, a luminance signal included in this analog image signal is extracted, this luminance signal is shifted to a predetermined voltage level, and based on the luminance voltage characteristic curve of the liquid crystal display panel. The drive signal generating means for correcting the voltage level of the shifted luminance signal to generate a drive voltage signal applied to each signal electrode of the liquid crystal panel, and the drive voltage signal generated by the drive signal generating means And a liquid crystal driving means for driving the liquid crystal display panel to display an analog image in a designated color.

According to the liquid crystal display device of the present invention, the liquid crystal driving voltage applied to the liquid crystal layer is changed to change the retardation of the liquid crystal layer, thereby changing the polarization state of the elliptically polarized light and changing the color of the transmitted light. In a liquid crystal display device in which a liquid crystal display panel to be changed is color-displayed based on input data, when the input data is an analog image signal, a brightness signal included in the analog image signal is extracted by the drive signal generating means, and the brightness signal The voltage level is shifted to a predetermined voltage level, the voltage level of the shifted luminance signal is corrected based on the luminance voltage characteristic curve of the liquid crystal display panel, and a drive voltage signal applied to each signal electrode of the liquid crystal panel is generated. Then, the liquid crystal driving means drives the liquid crystal display panel in color display with the designated color of the analog image.

Therefore, in a color liquid crystal display device using an ECB type liquid crystal display panel, an input analog image can be displayed in continuous gradation of achromatic color.

In a liquid crystal display device according to a second aspect of the present invention, a liquid crystal cell having a liquid crystal layer interposed between a pair of electrodes facing each other is provided with a retardation plate directly or at least on a surface on which light is incident. A liquid crystal display panel configured by arranging a polarizing plate through the liquid crystal layer is provided, and the light transmitted through the liquid crystal layer is elliptically polarized by the birefringence action of the liquid crystal, and the liquid crystal drive voltage applied to the liquid crystal layer is changed to change the liquid crystal layer By changing the retardation, a liquid crystal display device that color-displays a liquid crystal display panel that changes the polarization state of elliptically polarized light and changes the color of transmitted light based on input data, wherein the input data is digital image data, First drive signal generation means for generating a first drive voltage signal to be applied to each signal electrode of the liquid crystal display panel corresponding to the number of gradations designated by the digital image data; When the input data is an analog image signal, a luminance signal included in the analog image signal is extracted, the luminance signal is shifted to a predetermined voltage level, and the shift is performed based on the luminance voltage characteristic curve of the liquid crystal display panel. Second drive signal generating means for correcting the voltage level of the luminance signal to generate a second drive voltage signal to be applied to each signal electrode of the liquid crystal display panel, the first drive signal generating means and the first drive signal generating means. Selecting means for selectively selecting and outputting the first drive voltage signal and the second drive voltage signal generated by the second drive signal generating means, and the first selecting and outputting by this selecting means. The liquid crystal display panel is color-display-driven by the drive voltage signal and the second drive voltage signal in the specified color, and the analog image is displayed in the specified color by the liquid crystal display panel. It is characterized by comprising a liquid crystal driving unit for the color display drive Le, a.

According to the liquid crystal display device of the second aspect, by changing the liquid crystal driving voltage applied to the liquid crystal layer to change the retardation of the liquid crystal layer, the polarization state of the elliptically polarized light is changed and the color of the transmitted light is changed. In a liquid crystal display device for displaying a color of a liquid crystal display panel for changing the color on the basis of input data, when the input data is digital image data, the number of gradations designated by the digital image data is adjusted by the first drive signal generating means. Correspondingly, a first drive voltage signal applied to each signal electrode of the liquid crystal display panel is generated, and when the input data is an analog image signal, it is included in the analog image signal by the second drive signal generation means. A luminance signal is extracted, the luminance signal is shifted to a predetermined voltage level, and the luminance voltage characteristic curve of the liquid crystal display panel is used to change the luminance signal. The voltage level of the shifted luminance signal is corrected to generate a second drive voltage signal to be applied to each signal electrode of the liquid crystal display panel, and the selecting means causes the first drive signal generating means and the second drive signal to be generated. When the first drive voltage signal and the second drive voltage signal generated by the drive signal generation unit are selected and output, the liquid crystal drive unit outputs the selected and output first drive voltage signal and the first drive voltage signal. The liquid crystal display panel is color-display driven by the designated color of the digital image and the liquid crystal display panel is color-display driven by the designated color of the analog image by the driving voltage signal of 2.

Therefore, in the color liquid crystal display device, the input digital image data is displayed in multi-color, and the input analog image signal is achromatic black and white by the level shift process and the correction process based on the luminance-voltage characteristic curve. Since continuous gradation is displayed, conventional multi-color display of digital images and achromatic natural image display of analog images can be performed.

As a result, it is possible to improve the expressive power corresponding to the input image type in the color liquid crystal display device using the ECB type LCD panel.

In a liquid crystal display device according to a third aspect of the present invention, a liquid crystal cell having a liquid crystal layer interposed between a pair of electrodes facing each other is provided with a retardation plate directly or at least on the surface on which light is incident. A liquid crystal display panel configured by arranging a polarizing plate through the liquid crystal layer is provided, and the light transmitted through the liquid crystal layer is elliptically polarized by the birefringence action of the liquid crystal, and the liquid crystal drive voltage applied to the liquid crystal layer is changed to change the liquid crystal layer A liquid crystal display device for color-displaying a liquid crystal display panel that changes the polarization state of elliptically polarized light and changes the color of transmitted light by changing the retardation based on input data, wherein a plurality of liquid crystal display panels are provided on the display screen of the liquid crystal display panel. And a display area control unit that manages the display position information of each display area,
Storage means for storing the input data for each of the display areas based on display position information managed by the display area control means, and digital image data when the input data stored in the storage means is digital image data. A first drive signal generating means for generating a first drive voltage signal to be applied to each signal electrode of the liquid crystal display panel corresponding to the number of gradations specified by the input data stored in the storage means. In the case of an analog image signal, a luminance signal included in the analog image signal is extracted, the luminance signal is shifted to a predetermined voltage level, and the voltage level of the shifted luminance signal is based on the luminance characteristic curve of the liquid crystal display panel. And a second drive signal generating means for correcting the above and generating a second drive voltage signal applied to each signal electrode of the liquid crystal display panel. The liquid crystal display panel is color-display driven by the first drive voltage signal and the second drive voltage signal for each display area set by the area control means, in a designated color including an achromatic color, and Liquid crystal driving means for driving the liquid crystal display panel in a color display or an achromatic gradation display with an analog image in a designated color,
It is characterized by having.

According to the liquid crystal display device of the third aspect, by changing the liquid crystal driving voltage applied to the liquid crystal layer to change the retardation of the liquid crystal layer, the polarization state of the elliptically polarized light is changed and the color of the transmitted light is changed. In a liquid crystal display device in which a liquid crystal display panel for changing the color is displayed based on input data, a plurality of display areas are set on a display screen of the liquid crystal display panel by a display area control unit, and display of each display area is performed. Position information is managed, the input data is stored in the storage means for each of the display areas based on the display position information managed by the display area control means,
When the input data is digital image data, the first drive signal generating means applies a first drive voltage to each signal electrode of the liquid crystal display panel corresponding to the number of gradations specified by the digital image data. Signal is generated, second
When the input data is an analog image signal, the drive signal generating means extracts the brightness signal included in the analog image signal, shifts the brightness signal to a predetermined voltage level, and the brightness voltage characteristic of the liquid crystal display panel. When the voltage level of the shifted luminance signal is corrected based on the curve to generate the second drive voltage signal to be applied to each signal electrode of the liquid crystal display panel, the liquid crystal drive means causes the display area control means. By the first drive voltage signal and the second drive voltage signal for each display area set by, the liquid crystal display panel is color-display driven with the designated color of the digital image, and the achromatic color of the analog image is displayed. The liquid crystal display panel is driven to perform color display or achromatic color gradation display with the specified color including.

Therefore, in the color liquid crystal display device, an ECB type liquid crystal display is provided for each of a plurality of screens obtained by dividing the display screen into a multi-color display based on an input digital image and an achromatic continuous gradation display based on an input analog image. Display panel can be done at the same time.

As a result, it is possible to improve the expression power corresponding to the input image type in the color liquid crystal display device using the ECB type liquid crystal display panel, and to diversify the expression form.

Therefore, it is possible to expand the range of use when mounting the color liquid crystal display device using the ECB type LCD panel in various electronic devices.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to FIGS.

(First Embodiment) FIGS. 1 to 7 are views showing a first embodiment of a color liquid crystal display device 10 to which the present invention is applied.

First, the configuration will be described.

FIG. 1 is a diagram showing a cross section of a color liquid crystal display device 10 according to the first embodiment.

In this figure, a color liquid crystal display device 10 is shown.
Includes an ECB type liquid crystal display panel 4 and a drive control circuit 5 for driving the same, and displays an input image in different colors according to the drive voltage value applied to the ECB type LCD panel 4.

The ECB type LCD panel 4 includes a liquid crystal cell 30.
Is sandwiched between a pair of upper polarizing plate 40 and lower polarizing plate 41, and a retardation plate 42 is further interposed between the liquid crystal cell 30 and the upper polarizing plate 40, and the lower surface of the lower polarizing plate 41 (ECB type LCD
It is a reflection type in which a reflection plate 43 is provided on the back surface of the panel 4.

The liquid crystal cell 30 comprises a pair of transparent substrates 31, 3
2 are bonded together via a sealant 33, and the liquid crystal layer 3 is provided inside thereof.
4 is enclosed. Transparent electrodes 36 and 38 are formed in advance on the surfaces of the transparent substrates 31 and 32 facing each other, and alignment films 37 and 39 are formed so as to cover the transparent electrodes 36 and 38, respectively.

The alignment films 37 and 39 are provided to control the alignment direction of the liquid crystal molecules. For example, the alignment films 37 and 39 are subjected to an alignment treatment such as rubbing with a cloth,
The alignment direction of the liquid crystal molecules adjacent to each other is regulated so that the long axis direction of the liquid crystal molecules is along the alignment processing direction. Accordingly, the alignment state of the liquid crystal molecules 34a of the liquid crystal layer 34 is 180 ° to 27 ° from the one transparent substrate 31 toward the other transparent substrate 32.
It becomes a state that it is lined up so as to be twisted at an angle of 0 °. That is, the liquid crystal cell 30 is a super twisted nematic (STN) type liquid crystal cell.

The retardation plate 42 elliptically polarizes the linearly polarized light transmitted through the upper polarizing plate 40, and its optical axis (advance axis or slow axis) is adjacent to the retardation plate 42. They are arranged in a state of being slanted by a predetermined angle with respect to the transmission axis 40a of 40.

FIG. 2 shows the alignment treatment direction in the liquid crystal cell 30, the optical axis of the retardation plate 42, and the polarizing plate 4.
An example of a combination of 0 and 41 transmission axes is shown in a schematic plan view for each component. In the figure, straight lines 31a and 32a with single arrows indicate the alignment treatment directions applied to the lower alignment film 37 and the upper alignment film 39 in the liquid crystal cell 30, and straight lines 40a and 41a with double arrows respectively indicate the upper polarizing plate 40. And the transmission axis of the lower polarizing plate 41, and the straight line 42a is the optical axis of the retardation plate 42. The straight line S is a reference line extending in the left-right direction of the display surface and is provided for convenience of explanation.

As shown in FIG. 2, the alignment treatment directions 31a and 32a of the liquid crystal cell 30 are set in directions opposite to each other with respect to the reference line S by a predetermined angle θ, whereby the liquid crystal molecules 34a. The alignment state of the lower transparent substrate 3
The orientation is twisted in the angle and direction indicated by arrow T from the first side toward the upper transparent substrate 32 side.

Further, the optical axis 42a of the phase difference plate 42 is a slow axis here, and a predetermined tilt angle ψ with respect to the reference line S.
It crosses at an angle. Further, in this embodiment, the transmission axes 40a, 41 of the pair of upper and lower polarizing plates 40, 41 are arranged.
a is substantially parallel to each other, and the optical axis 42a of the retardation plate 42
The tilt angle φ is deviated from the diagonal direction.

In the color liquid crystal display device 1 having the ECB type LCD panel 4 having the above structure, the polarization effect of the retardation plate 42 and the polarization action of the liquid crystal cell 30 make the light incident on the ECB type LCD panel 4 and the reflection plate 43. ECB type LC reflected by
The light emitted to the outside of the D panel 4 is colored,
At this time, the display color can be arbitrarily changed by changing the magnitude of the voltage applied to the liquid crystal cell 30 in the drive control circuit 5.

The coloring mechanism will be described below. Light from the outside becomes linearly polarized light as it passes through the upper polarizing plate 40, and further passes through the retardation plate 42 in the process of passing through the retardation plate 4.
It becomes elliptically polarized light by being subjected to a polarization action according to the optical arrangement conditions such as the position of the second optical axis 42a and the retardation value.
While passing through the liquid crystal cell 30, the elliptically polarized light is further subjected to a polarization action according to the optical arrangement condition of the liquid crystal cell 30 and the value of retardation, and its polarization state changes.

When the elliptically polarized light that has been polarized by the retardation plate 42 and the liquid crystal cell 30 enters the lower polarization plate 41, the transmission axis 41 of the lower polarization plate 41 out of the elliptically polarized light.
Only the light having the wavelength of the polarization component corresponding to a is transmitted through the lower polarizing plate 41. Therefore, the light (linearly polarized light) emitted from the lower polarizing plate 41 is in a colored state. The hue is mainly determined by the retardation of the retardation plate 42 and the retardation of the liquid crystal cell 30.

Further, the light that has passed through the lower polarizing plate 41 is reflected by the reflecting plate 43, and EC in the route opposite to the above-described optical route.
Since the light is emitted to the upper surface side of the B-type LCD panel 4, a display in the color of the emitted light can be obtained.

The retardation of the retardation plate 42 is
The product Δn of the refractive index anisotropy Δn of the retardation plate 42 and the plate thickness d
The retardation of the liquid crystal cell 30 is determined by the product Δn · d of the refractive index anisotropy Δn of the liquid crystal layer 34 and the liquid crystal layer thickness d, and the alignment state of the liquid crystal molecules 34a. Therefore, by changing the voltage value applied to the liquid crystal cell 30 to change the alignment state of the liquid crystal molecules 34a, the retardation of the liquid crystal cell 30 is changed and the polarization action in the liquid crystal cell 30 is changed.

Specifically, when the voltage is not applied to the liquid crystal cell 30, the light incident on the ECB type LCD panel 4 has the polarization effect of the retardation plate 42 and the initial twist angle T of the liquid crystal molecules 34a. The polarized light is subjected to a corresponding polarization action, and becomes an elliptically polarized light accordingly. Then, the light passes through the lower polarization plate 41, is reflected by the reflection plate 43, and travels in the opposite path to form an ECB type LCD.
The light is emitted to the upper surface side of the panel 4. The display color at that time is a color corresponding to the retardation of both the retardation plate 42 and the liquid crystal layer 34 oriented at the initial twist angle T.

Further, the transparent electrodes 36 and 38 of the liquid crystal cell 30.
When a voltage is applied in the meantime, the liquid crystal molecules 34a gradually rise from the initial twisted state as the voltage value increases. The retardation of the liquid crystal cell 30 changes according to the raised alignment state, and the light incident on the ECB type LCD panel 4 has a polarization effect of the retardation plate 42 and a polarization effect according to the changed retardation of the liquid crystal cell 30. And becomes elliptically polarized light accordingly. Therefore, the display color at that time is different from the color when no voltage is applied to the liquid crystal cell 30 described above.

Further, in the liquid crystal cell 30, liquid crystal molecules 34a are formed.
When a voltage is applied that causes the liquid crystal to rise and align almost vertically, the retardation of the liquid crystal cell 30 also becomes substantially “0”. Therefore, the polarization effect of the liquid crystal cell 30 disappears,
The light incident on the ECB type LCD panel 4 receives the phase difference plate 42.
It becomes elliptically polarized light only by the polarization effect of. Then, the elliptically polarized light is emitted from the ECB type LCD panel 4 through the lower polarizing plate 41, the reflecting plate 43 and the reverse path thereof, and is colored in a color corresponding to the retardation of the retardation plate 42.

Next, an example of the drive control circuit 5 configured to display four colors and monochrome achromatic color on the ECB type LCD panel 4 will be described.

FIG. 3 is a block diagram showing the overall structure of the color liquid crystal display device 10 including the drive control circuit 5.

In FIG. 3, the drive control circuit 5 is connected between the ECB type LCD panel 4, the personal computer (PC) 11 and the video device 12, and the drive control circuit 5 is a data / voltage conversion circuit. 51, a level shift characteristic correction circuit 52, a mode switch 53, and a selection circuit 54, and generates a liquid crystal drive voltage signal in which the number of gradations is set according to the display color based on digital image data input from the personal computer 11. Then, by applying the liquid crystal driving voltage signal to the ECB type LCD panel 4, multi-color display of an input digital image is performed and a luminance signal is extracted from an analog video signal input from the video device 12. , The brightness signal is based on the brightness-voltage characteristic curve of the ECB type LCD panel 4 described later. And Ku level shift processing, generates a brightness correction voltage signal of the curve by performing luminance correction processing polygonal line approximation, the luminance correction voltage signal ECB type L
By applying it to the CD panel 4, an achromatic color monochrome continuous gradation display of the input analog image is performed.

The data / voltage conversion circuit 51 has the same circuit configuration as that of the conventional data / voltage conversion circuit 2 described above. As shown in FIG. 13, the color selection table 2a and D / A are used.
The personal computer 1 includes a conversion circuit 2b.
Digital image data (for example, R,
G and B each 2 bits) is converted into a color number value in the order of voltage level by the color selection table 2a, and the color number value is output to the D / A conversion circuit 2b to generate a drive voltage signal to select the selection circuit 5.
It is output to 4.

As shown in FIG. 4, the level shift characteristic correction circuit 52 is composed of a video signal processing circuit 52a, a level shift circuit 52b and a luminance voltage characteristic correction circuit 52c. The video signal processing circuit 52a converts the analog video signal input from the video device 12 into the luminance signal V
a is extracted and output to the level shift circuit 52b.

The level shift circuit 52b shifts the voltage level of the luminance signal Va input from the video signal processing circuit 52a by 2V1 based on the reference voltage V1 input in FIG. 4, as shown in FIG. And outputs the shifted luminance voltage signal Vb to the luminance voltage characteristic correction circuit 52c. In FIG. 5, the white MAX (maximum) level is 0.
The MIN (minimum) level of V and black is Va.

The luminance voltage characteristic correction circuit 52c has a shift luminance voltage signal Vb input from the level shift circuit 52b.
Based on the luminance-voltage characteristic curve of the ECB type LCD panel 4 shown in FIG. 6, the polygonal line approximation correction as shown in FIG. 7 is performed so that the relationship between the shift luminance voltage signal Vb level and the luminance characteristic approaches a straight line. Then, the corrected luminance signal Vc is output to the selection circuit 54.

That is, the luminance voltage characteristic correction circuit 52c
In the polygonal line approximation correction diagram shown in FIG. 7, in a region where the input shift luminance voltage signal Vb is VI in the drawing, the tilt correction luminance signal Vc in the drawing is generated, and the shift luminance voltage signal Vb is shown in the drawing. In the area of VII, the tilt correction luminance signal Vc in the figure is generated, and the shift luminance voltage signal Vb is V in the figure.
In the region above II, the corrected luminance signal Vc for the tilt in the figure is generated.

Returning to FIG. 3 again, the mode switch 53
Outputs a mode signal designating whether the image input to the drive control circuit 5 is digital or analog to the selection circuit 54 to control the selection state of the selection circuit 54.

The selection circuit 54 selects the drive voltage signal input from the data / voltage conversion circuit 51 and the corrected luminance signal Vc input from the level shift characteristic correction circuit 52 based on the mode signal input from the mode switch 53. One of them is selected and output to the ECB type LCD panel 4.

The ECB type LCD panel 4 has a selection circuit 54.
The input digital image is displayed in multi-color by the drive voltage signal input from the same, and the input video signal is displayed in achromatic black and white gradation by the corrected luminance signal Vc input from the selection circuit 54.

Next, the operation of the first embodiment will be described.

In the color liquid crystal display device 10 shown in FIG.
When digital image data is input from the personal computer 11, the data / voltage conversion circuit 51 converts it into color number values in the order of voltage levels by the color selection table 2a and outputs the color number values to the D / A conversion circuit 2b. A drive voltage signal is generated and output to the selection circuit 54.

At this time, the mode switch 53 outputs a mode signal to the selection circuit 54 so as to select the input signal from the data / voltage conversion circuit 51, and the selection circuit 54 uses the mode signal to select the data / voltage conversion circuit. The drive voltage signal input from 51 is selected to display an ECB type LCD.
The output to the panel 4 causes the ECB type LCD panel 4 to display the input image data in multi-color in the designated color.

In the color liquid crystal display device 10 of FIG. 3, when a video signal is input from the video device 12,
The video signal processing circuit 52a in the level shift characteristic correction circuit 52 extracts only the luminance signal Va from the video signal and outputs it to the level shift circuit 52b. In the level shift circuit 52b, the luminance signal Va is shown in FIG. Based on the input reference voltage V1 shown, the voltage level is shifted by 2V1 as shown in FIG. 5, and the shifted luminance voltage signal Vb is output to the luminance voltage characteristic correction circuit 52c.

In the brightness voltage characteristic correction circuit 52c, the shift brightness voltage signal V input from the level shift circuit 52b is input.
b is a voltage of the shift luminance voltage signal Vb level so that the relationship between the shift luminance voltage signal Vb level and the luminance characteristic approaches a straight line based on the luminance-voltage characteristic curve of the ECB type LCD panel 4 shown in FIG. The polygonal line approximation correction shown in FIG. 7 is performed according to the level, and the corrected luminance signal Vc is generated and output to the selection circuit 54.

At this time, the mode switch 53 outputs a mode signal to the selection circuit 54 so as to select the input signal from the level shift characteristic correction circuit 52, and the selection circuit 54.
Then, the correction luminance signal Vc input from the level shift characteristic correction circuit 52 is selected by this mode signal and EC
By being output to the B-type LCD panel 4, the input video signal is displayed on the ECB-type LCD panel 4 in an achromatic black and white continuous gradation.

As described above, in the color liquid crystal display device 10 of the first embodiment, the input digital image data is displayed in multi-color, and the input video signal is subjected to the level shift processing and the luminance-voltage. Since the achromatic color is displayed in continuous black and white by the correction processing that approximates the characteristic curve to the polygonal line, it is possible to perform conventional multicolor display of a digital image and achromatic natural image display of an analog image.

As a result, the expressive power corresponding to the input image type in the color liquid crystal display device 10 using the ECB type LCD panel 4 can be improved.

(Second Embodiment) FIGS. 8 to 11 are views showing a second embodiment of a color liquid crystal display device 100 to which the present invention is applied.

First, the structure will be described.

FIG. 8 is a block diagram of the entire structure of the color liquid crystal display device 100 of the second embodiment, and the same reference numeral is used because the ECB type LCD panel 4 shown in the first embodiment is used. Is attached and the description is omitted.

In FIG. 8, the color liquid crystal display device 1
00 is the controller 101 and the screen list memory 10
2, the area control circuit 103, the image memory 104, the data voltage conversion circuit 105, the A / D conversion circuit 106, the luminance information extraction circuit 107, the image memory 108, the data voltage conversion circuit 109, the selection circuit 110, and the ECB type LCD panel 4. It is configured.

The controller 101 displays the setting instruction of the window screen display area in the color liquid crystal display device 100 and the list data of each display area in the screen list memory 1.
Set to 02.

As shown in FIG. 9, the screen list memory 102 forms a memory area for storing two kinds of screen list data of a color screen and a black and white gradation screen. In each of the memory areas, the screen list data is stored. Each item information of the screen number and the area designation (the coordinates of the upper left corner and the lower right corner of the display area) is stored in the order of the screen number and is set by the controller 101.

As shown in FIG. 10, the area control circuit 103 is composed of a comparison circuit 103a, an x counter 103b, ay counter 103c and a highest priority screen selection circuit 103d.

Six comparison circuits 103a are provided corresponding to the allowable number of window screens displayed on the ECB type LCD panel 4, and each comparison circuit is an area of each screen input from the screen list memory 102. By comparing the designated data (upper left coordinate and lower right coordinate) with the x count value and the y count value input from the x counter 103b and the y counter 103c, it is determined whether the display position of the screen is within the display area of the sub screen. If it is within the sub-screen display area, the sub-screen selection signal PEn (n = 1 to 6) = 1
Is output to the highest priority screen selection circuit 103d, the image memory 104, and the image memory 108 when PEn is outside the sub-screen display area.

The highest priority screen selection circuit 103d uses the image memories 104, 108 and 108 as the highest priority screen selection signal PS when PEn = 1 and the minimum n value among the PEn signals input from the comparison circuit 103a. Circuit 11
Output to 0.

The read address of the image memory 104 is reset by the vertical synchronizing signal, and digital image data input from a digital image source by a personal computer or the like is sequentially stored by a 4-bit control signal. By the input sub-screen selection signal PEn and the highest priority screen selection signal PS,
The 4-bit digital image data in the corresponding storage area is read and output to the data voltage conversion circuit 105.

The data voltage conversion circuit 105 D / A-converts each digital image data of the sub-screen area and the highest-priority screen area input from the image memory 104 based on the input color-designated reference voltages V9 to V15. Then, a drive voltage signal is generated and output to the selection circuit 110.

The reference voltages V9 to V15 and the reference voltages V1 to V8 input to the data voltage conversion circuit 109 which will be described later are the same as the luminance of FIG. 6 shown in FIG. 7 in the first embodiment. It is a voltage for color designation that is set by polygonal line approximation of the voltage characteristic curve.

The A / D conversion circuit 106 A / D converts an analog image signal input from an analog image source by a video device or the like, and outputs digital image data to the luminance information extraction circuit 107.

The brightness information extraction circuit 107 extracts brightness information from the digital image data input from the A / D conversion circuit 106 and outputs it to the image memory 108 as 6-bit brightness information.

The read address of the image memory 108 is reset by the vertical synchronizing signal, and the brightness information extracting circuit 1
The luminance information input from 07 is sequentially stored, and
Sub-screen selection signal P input from the area control circuit 103
In accordance with En and the highest priority screen selection signal PS, the 6-bit luminance information of the corresponding storage area is read and output to the data voltage conversion circuit 109.

The data voltage conversion circuit 109 receives the luminance information of the sub-screen area and the highest-priority screen area, which are input from the image memory 108, on the basis of the input reference voltages V1 to V8 for designating continuous gradation of achromatic color. The D / A conversion is performed to generate a drive voltage signal and the drive voltage signal is output to the selection circuit 110.

The selection circuit 110 is the data voltage conversion circuit 1
Drive voltage signal input from the data conversion circuit 1 and the data conversion circuit 1
09. The drive signal input from 09 has a higher priority and outputs it to the ECB type LCD panel 4, and the data voltage conversion circuit 105 receives the highest priority screen selection signal PS input from the area control circuit 103. Alternatively, the drive signal of the corresponding highest priority screen is selected from the drive signals input from the data conversion circuit 109 and output to the ECB type LCD panel 4.

Next, the operation of the second embodiment will be described.

In the color liquid crystal display device 100 of FIG. 8, the color liquid crystal display device 1 is controlled by the controller 101.
00, the screen number and area designation (coordinates of the upper left and lower right of the display area) are used as the screen list memory 1 as the setting instruction of the window screen display area and list data of each display area.
It is set to 02.

In the area control circuit 103, the area specifying data (upper left coordinates and lower right coordinates) of each screen input from the screen list memory 102 is input by the comparison circuit 103a.
Is compared with the x count value and the y count value input from the x counter 103b and the y counter 103c, it is determined whether or not the display position of the screen is within the display area of the sub screen. Is output, PEn = 0 is output to the highest priority screen selection circuit 103d, the image memory 104, and the image memory 108 when the sub-screen selection signal PEn (n = 1 to 6) = 1 is outside the sub-screen display area. To be done.

In the highest priority screen selection circuit 103d, PEn = 1 in the PEn signal input from the comparison circuit 103a.
Which has the smallest n value as the highest priority screen selection signal PS is the image memory 104, the image memory 108 and the selection circuit 1.
It is output to 10.

In the image memory 104, the read address is reset by the vertical synchronizing signal, the digital image data input from the digital image source by the personal computer or the like is sequentially stored by the 4-bit control signal, and the area control is performed. According to the sub-screen selection signal PEn and the highest-priority screen selection signal PS input from the circuit 103, 4-bit digital image data in the corresponding storage area is read and output to the data voltage conversion circuit 105.

In the data voltage conversion circuit 105, each digital image data of the sub-screen area and the highest-priority screen area input from the image memory 104 is D / A converted based on the input color-designated reference voltages V9 to V15. Then, a drive voltage signal is generated and output to the selection circuit 110.

In the A / D conversion circuit 106, when the analog image signal input from the analog image source is A / D converted by the video device or the like and output to the luminance information extraction circuit 107 as digital image data, In the luminance information extraction circuit 107, the luminance information is extracted from the digital image data input from the A / D conversion circuit 106, and 6
It is output to the image memory 108 as bit-structured luminance information.

In the image memory 108, the read address is reset by the vertical synchronizing signal, the brightness information input from the brightness information extraction circuit 107 is sequentially stored, and the sub-screen selection signal input from the area control circuit 103 is also stored. By PEn and the highest priority screen selection signal PS,
The 6-bit luminance information of the corresponding storage area is read and output to the data voltage conversion circuit 109.

In the data voltage conversion circuit 109, the luminance information of the sub-screen area and the highest-priority screen area input from the image memory 108 is based on the input reference voltages V1 to V8 of the achromatic continuous gradation designation. D / A conversion is performed to generate a drive voltage signal, which is output to the selection circuit 110.

In the selection circuit 110, one of the drive voltage signal input from the data voltage conversion circuit 105 and the drive signal input from the data conversion circuit 109, which has the higher priority, is selected and displayed on the ECB type LCD panel 4. The drive signal of the corresponding highest priority screen among the drive signals input from the data voltage conversion circuit 105 or the data conversion circuit 109 is selected by the highest priority screen selection signal PS output from the area control circuit 103. ECB type L
It is output to the CD panel 4.

In the ECB type LCD panel 4, when the drive voltage signal selected and input from the selection circuit 110 for each sub-screen is based on the input digital image, multi-color display based on 4-bit color designation is performed. If it is based on an analog image, achromatic continuous tone display based on 6-bit achromatic color continuous tone designation is performed.

As a result, for example, as shown in FIG.
When the display area of the CB type LCD panel 4 is 480 dots vertically × 480 dots horizontally, as shown in the figure, the sub window screens 2 and 3 display multi-color digital images and the sub window screens 4 and 6. , An achromatic continuous gradation display of an analog image is simultaneously performed.

In the color liquid crystal display device 100 of the second embodiment, in order to finely control the gradation for the achromatic continuous gradation display based on the analog image, the data voltage conversion circuit 1 is used.
In 09, the data to be handled is 6 bits, and the number of bits is larger than 4 bits of the data handled by the data voltage conversion circuit 105 for multicolor display based on a digital image.

As described above, in the color liquid crystal display device 100 according to the second embodiment, the multi-color display based on the input digital image and the input analog image are provided for each of the plurality of sub-screens obtained by dividing the display screen. Based on the achromatic continuous tone display, the ECB type LCD panel 4 can be simultaneously performed.

As a result, it is possible to improve the expression power corresponding to the input image type in the color liquid crystal display device 100 using the ECB type LCD panel 4 and to diversify the expression form.

Therefore, it is possible to expand the range of use when the color liquid crystal display device using the ECB type LCD panel is mounted on various electronic devices.

[0098]

According to the liquid crystal display device of the first aspect of the present invention, in the color liquid crystal display device using the ECB type liquid crystal display panel, the input analog image can be displayed in achromatic continuous gradation.

According to the liquid crystal display device of the second aspect of the present invention, in the color liquid crystal display device, the input digital image data is displayed in multi-color, and the input analog image signal is subjected to the level shift processing and the luminance- Since achromatic color black and white continuous gradation is displayed by the correction processing based on the voltage characteristic curve, conventional multicolor display of digital images and achromatic natural image display of analog images can be performed.

As a result, the expressive power corresponding to the input image type in the color liquid crystal display device using the ECB type LCD panel can be improved.

According to the liquid crystal display device of the third aspect of the invention, in the color liquid crystal display device, a multicolor display based on an input digital image and an input analog image are performed for each of a plurality of screens into which the display screen is divided. The achromatic continuous tone display can be simultaneously performed on the ECB type liquid crystal display panel.

As a result, it is possible to improve the expression power corresponding to the input image type in the color liquid crystal display device using the ECB type liquid crystal display panel, and it is possible to diversify the expression form.

Therefore, it is possible to expand the range of use when the color liquid crystal display device using the ECB type LCD panel is mounted on various electronic devices.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a first embodiment of a color liquid crystal display device to which the present invention has been applied.

FIG. 2 is a schematic diagram showing, for each component, an example of a combination of an alignment direction of liquid crystal molecules, an optical axis of a retardation plate, and a transmission axis of a polarizing plate in the liquid crystal cell of the first embodiment.

FIG. 3 is a block diagram showing the overall configuration of the color liquid crystal display device of the first embodiment.

FIG. 4 is a diagram showing a circuit configuration inside a level shift characteristic correction circuit of FIG. 3;

FIG. 5 is a diagram for explaining the operation of the level shift circuit of FIG.

6 is a diagram showing a luminance-voltage characteristic curve of the ECB type LCD panel of FIG.

FIG. 7 is a polygonal line approximation correction diagram of the luminance-voltage characteristic curve of FIG.

FIG. 8 is a block diagram showing the overall configuration of a second embodiment of a color liquid crystal display device to which the present invention has been applied.

9 is a diagram showing a memory configuration in the screen list memory of FIG.

10 is a diagram showing a block configuration inside the area control circuit of FIG. 8;

11 is a diagram showing an example of a sub-screen displayed on the ECB type LCD panel of FIG.

FIG. 12 is a schematic configuration diagram of a color liquid crystal display device using a conventional ECB type LCD panel.

13 is an internal block configuration diagram of the data voltage / conversion circuit of FIG.

14 is a diagram showing an example of data setting of the color selection table of FIG.

[Explanation of symbols]

 4 ECB type LCD panel 5 Drive control circuit 10, 100 Color liquid crystal display device 11 Personal computer 12 Video device 30 Liquid crystal cell 31, 32 Transparent substrate 33 Seal material 34 Liquid crystal layer 36, 38 Transparent electrode 37, 39 Alignment film 40 Upper polarizing plate 41 Lower polarizing plate 42 Phase difference plate 43 Reflector 51 Data / voltage conversion circuit 52 Level shift characteristic correction circuit 52a Video signal processing circuit 52b Level shift circuit 52c Luminance voltage characteristic correction circuit 53 Mode switch 54 Selection circuit 101 Controller 102 Screen list memory 103 area control circuit 104 image memory 105 data voltage conversion circuit 106 A / D conversion circuit 107 luminance information extraction circuit 108 image memory 109 data voltage conversion circuit 110 selection circuit

Claims (4)

[Claims] 1. A liquid crystal cell in which a liquid crystal layer is interposed between a pair of electrodes facing each other, at least on a surface on which light is incident,
A liquid crystal display panel comprising a liquid crystal display panel in which a polarizing plate is arranged directly or via a retardation plate, the light transmitted through the liquid crystal layer is elliptically polarized by the birefringence action of the liquid crystal, and a liquid crystal drive voltage applied to the liquid crystal layer. By changing the retardation of the liquid crystal layer by changing the, the liquid crystal display device for color-displaying the liquid crystal display panel which changes the polarization state of the elliptically polarized light and changes the color of the transmitted light based on the input data, wherein the input data is In the case of an analog image signal, a luminance signal included in this analog image signal is extracted, this luminance signal is shifted to a predetermined voltage level, and the voltage of the shifted luminance signal based on the luminance voltage characteristic curve of the liquid crystal display panel. A drive signal generating unit that corrects the level and generates a drive voltage signal to be applied to each signal electrode of the liquid crystal panel, and a drive signal generating unit. Ri liquid crystal display device comprising: the liquid crystal drive means, to said liquid crystal display panel in a specified color the analog image by the drive voltage signal generated color display drive. 2. A liquid crystal cell in which a liquid crystal layer is interposed between a pair of electrodes facing each other, at least on a surface on which light is incident,
A liquid crystal display panel comprising a liquid crystal display panel in which a polarizing plate is arranged directly or via a retardation plate, the light transmitted through the liquid crystal layer is elliptically polarized by the birefringence action of the liquid crystal, and a liquid crystal drive voltage applied to the liquid crystal layer. By changing the retardation of the liquid crystal layer by changing the, the liquid crystal display device for color-displaying the liquid crystal display panel which changes the polarization state of the elliptically polarized light and changes the color of the transmitted light based on the input data, wherein the input data is In the case of digital image data, first drive signal generation means for generating a first drive voltage signal applied to each signal electrode of the liquid crystal display panel corresponding to the number of gradations designated by the digital image data, When the input data is an analog image signal, a luminance signal included in the analog image signal is extracted, and the luminance signal is shifted to a predetermined voltage level. Second driving signal generation for correcting the voltage level of the shifted luminance signal based on the luminance voltage characteristic curve of the liquid crystal display panel to generate the second driving voltage signal applied to each signal electrode of the liquid crystal display panel Means and selection means for selectively selecting and outputting the first drive voltage signal and the second drive voltage signal generated by the first drive signal generation means and the second drive signal generation means By the first drive voltage signal and the second drive voltage signal selected and output by the selection means, the liquid crystal display panel is color-display driven with the specified color of the digital image, and the analog image is specified with the specified color. 2. A liquid crystal display device comprising: a liquid crystal driving means for driving the liquid crystal display panel to perform color display. 3. A liquid crystal cell in which a liquid crystal layer is interposed between a pair of electrodes facing each other, at least on a surface on which light is incident,
A liquid crystal display panel comprising a liquid crystal display panel in which a polarizing plate is arranged directly or via a retardation plate, the light transmitted through the liquid crystal layer is elliptically polarized by the birefringence action of the liquid crystal, and a liquid crystal drive voltage applied to the liquid crystal layer. By changing the retardation of the liquid crystal layer to change the polarization state of the elliptically polarized light to change the color of the transmitted light. A plurality of display areas are set on the display screen of the display area, and display area control means for managing display position information of each display area, and the input data based on the display position information managed by the display area control means. Storage means for storing each display area, and when the input data stored in the storage means is digital image data, First drive signal generation means for generating a first drive voltage signal to be applied to each signal electrode of the liquid crystal display panel corresponding to a specified number of gradations; and input data stored in the storage means are analog. At the time of the image signal, the luminance signal included in the analog image signal is extracted, the luminance signal is shifted to a predetermined voltage level, and the voltage level of the shifted luminance signal is changed based on the luminance characteristic curve of the liquid crystal display panel. A second drive signal generation unit that corrects and generates a second drive voltage signal to be applied to each signal electrode of the liquid crystal display panel; and the first drive signal for each display region set by the display region control unit. Of the drive voltage signal and the second drive voltage signal of
Liquid crystal driving means for driving the liquid crystal display panel to perform a color display of the digital image with a designated color, and driving the liquid crystal display panel to perform a color display drive or an achromatic gradation display drive of the analog image with a designated color including an achromatic color, A liquid crystal display device comprising: 4. The drive signal generating means and the second drive signal generating means correct the luminance signal with the voltage level shifted based on voltage data obtained by polygonal approximation of the luminance voltage characteristic curve of the liquid crystal display panel. 4. The liquid crystal display device according to claim 1, wherein the drive voltage signal and the first drive voltage signal are generated.