JPH07334126A - Liquid crystal display device and its driving method - Google Patents

Abstract

PURPOSE:To provide a liquid crystal display device displaying a color image by using a liquid crystal display element for displaying a color complied with an applied voltage. CONSTITUTION:A CPU 11 executes a program and writes image data in an image memory 15. A display control circuit 17 reads the image data and transfers them to a transformation table 19. The transformation table 19 stores a color instructed by the image data and selection data for selecting a voltage to be applied to the liquid crystal in order to display the color and outputs the corresponding selection data. With regard to the image data instructing a color not to be displayed, selection data for selecting a voltage for displaying an approximated color is set. A multiplexer 23 selects one of the voltages V0-V7 supplied from a voltage generating circuit 21 according to the selected data and supplys it to a column driver 33. The column driver 33 drives a liquid crystal display element 25 by using the supplied voltage and displays a proper color.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color liquid crystal display device using a liquid crystal display element for displaying a color corresponding to an applied voltage and a driving method thereof.

[0002]

2. Description of the Related Art Conventionally, a color display device obtains an arbitrary display color by additive color mixture of three primary colors of red, green and blue, and has dots corresponding to the three primary colors of red, green and blue. Then, this color display device displays each arbitrary color by independently controlling the brightness of the red, green, and blue dots corresponding to each primary color. For this reason, television sets, personal computers, etc. equipped with color display devices are
Three brightness data corresponding to the three primary colors of blue are supplied to the display device, the brightness of the dots of each color is controlled according to the brightness data of these three primary colors, and the desired color is displayed in pixel units.

Similarly, in a color liquid crystal display device, electrodes for forming a plurality of dots are arranged so as to form one pixel from three dots corresponding to color filters of three primary colors (red, green and blue). By independently controlling the intensity of light passing through each of the dots, the display color of one pixel composed of the three dots is driven.

The liquid crystal display device provided with the three primary color filters is used in a television set, a personal computer or the like as a transmissive liquid crystal display device having a strong light source on the back because of its low light transmittance. However, since the color liquid crystal display element has a large light absorption by the color filter, it is not possible to obtain a reflection type color liquid crystal display device which does not require illumination from the back surface.

An electric field control birefringence effect type is known as a liquid crystal display element capable of color display of a plurality of colors without using a color filter. This electric field control birefringence effect type liquid crystal display element is composed of a liquid crystal cell in which liquid crystal is sealed between a pair of substrates subjected to an alignment film treatment, and two polarizing plates arranged so as to sandwich the liquid crystal cell. By changing the molecular alignment of the liquid crystal by applying an electric field, the birefringence effect of the liquid crystal layer is changed, and the change of the birefringence effect changes the spectral distribution of the light transmitted through the liquid crystal cell to change the desired color. Is displayed for color display.

The electric field control birefringence effect type liquid crystal display element can display color without using a color filter, and the display is bright because light is not absorbed by the color filter. Therefore, there is an advantage that a reflective color liquid crystal display device can be realized and the structure of the liquid crystal display element is simple.

[0007]

A liquid crystal display element of the electric field control birefringence effect type has a plurality of desired colors by controlling the voltage applied between electrodes facing each other arranged on the substrates facing each other of the liquid crystal cell. One dot forms one pixel, and the display color is in one-to-one correspondence with each voltage applied between the electrodes forming the one pixel. Therefore, in the three luminance data corresponding to the three primary colors of red, green and blue supplied to the conventional color display device, the electric field control birefringence effect type liquid crystal display element that displays a plurality of colors in one pixel is turned on. I couldn't drive.

Further, in the electric field control birefringence effect type liquid crystal display element, the display color changes along a predetermined locus on the chromaticity diagram according to the applied voltage, and the display color changes according to the applied voltage. Since it is uniquely determined, it is difficult to obtain an arbitrary display color according to the supplied luminance data of red, green, and blue.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a liquid crystal display device for displaying a color image using a liquid crystal display element for displaying a color corresponding to an applied voltage and a driving method thereof. And Further, the present invention provides an electric field control birefringence effect type liquid crystal display device capable of displaying a display color designated by red, green and blue luminance data with a simple circuit configuration and a driving method thereof. To aim. Further, the present invention provides a color liquid crystal display device and a driving method thereof for selecting and displaying a color closest to a display color designated by red, green, and blue luminance data from displayable display colors. With the goal.

[0010]

In order to achieve the above object, a color liquid crystal display device according to the present invention includes a liquid crystal display element for displaying a plurality of colors according to an applied voltage, and a designated display color of the liquid crystal display element. A color indicating means for indicating, and a relationship between a display color determined based on a relationship between the applied voltage to the liquid crystal display element and the indicating display color and a voltage value corresponding thereto, and the color indicating means. A conversion unit that outputs voltage selection data corresponding to the designated designated display color, a voltage generation unit that outputs a plurality of generated voltages, and a voltage that corresponds to the voltage selection data output by the conversion unit are stored in the voltage generation unit. Supplying means for displaying an image by selecting from the generated voltage and supplying it to the liquid crystal display element,
It is characterized by including.

Further, according to the driving method of the liquid crystal display device of the present invention, there is provided a color instructing step for instructing a display color and selection data for selecting a voltage corresponding to the designated display color instructed by the color instructing step. A conversion step of converting to a voltage, a voltage generation step of generating a plurality of voltages, and a selection step of selecting a voltage corresponding to the selection data from the plurality of voltages generated by the voltage generation step according to the selection data. And a driving step of displaying a color image on the liquid crystal display device by supplying and driving the voltage selected by the selection step to the liquid crystal display device that displays a color according to the applied voltage. Characterize.

[0012]

According to the present invention, the table for storing the relationship between the display color of the liquid crystal display device for displaying the color corresponding to the applied voltage and the corresponding voltage value and outputting the voltage data corresponding to the designated color. Since a means is provided, a simple circuit configuration,
An appropriate color image can be displayed on the liquid crystal display device. Further, when a color which cannot be displayed by the electric field control birefringence effect type liquid crystal display device is designated, a table means for outputting a voltage corresponding to a color which is most similar to the color is provided, so that an appropriate color is provided. Images can be displayed on a liquid crystal display device.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a circuit configuration of a birefringence control type liquid crystal display device and a driving circuit thereof according to an embodiment of the present invention.

As shown in the figure, this circuit is a CPU that controls the entire system according to a predetermined program.
11, a program memory 13 for storing an operation program of the CPU 11, for example, an image creation program, and C
An image memory (display memory) 15 in which image data is written by the PU 11, a display control circuit 17 that sequentially reads the image data stored in the image memory 15 under the control of the CPU 11, and an image read by the display control circuit 17. Conversion table 19 for converting data into voltage selection data
And a voltage generation circuit 21 that generates eight predetermined voltages V0 to V7, and one of the eight voltages V0 to V7 generated by the voltage generation circuit 21 according to the output of the conversion table 19 is selected. It is composed of a multiplexer 23 for outputting the output and an active matrix liquid crystal display element 25.

Active matrix liquid crystal display element 25
Is a liquid crystal display panel 31 on which electrodes and thin film transistors (TFTs) 45 are formed, and a multiplexer 23.
Sample the output signal of the data line 49 and TF
A column driver (drain driver) 33 supplied to the pixel electrode 43 via T45 and a row driver (gate driver) 35 for turning on / off the TFT 45.

As shown in FIG. 1 or 12, a transparent pixel electrode 43 and a pixel electrode 43 are provided on a lower substrate 41 of a pair of transparent substrates 41 and 51 (eg, glass substrates) that constitute the liquid crystal display panel 31. The TFTs 45 to which the sources are connected are arranged in a matrix. In addition, the lower substrate 41
A gate line (scanning line) 47 is wired in the row direction, and the gate line 47 is connected to the gate electrode of the TFT 45 in the corresponding row. Further, a data line (gradation signal line) 49 is laid out in the column direction and connected to the drain of the TFT 45 in the corresponding column. Further, on the lower substrate 41, as shown in FIG.
And the alignment film 6 on the TFT 45, which has been subjected to a predetermined alignment treatment.
0 is provided, and further, a polarizing plate 53 is provided on the back side thereof, and a reflecting plate 55 made of metal such as aluminum is provided on the back side of the polarizing plate 53.

On the other hand, each pixel electrode 43 is provided on the upper substrate 51.
A transparent counter electrode 58 is formed so as to face the. Furthermore, on the counter electrode 58 of the upper substrate 51, an alignment film 59 that has been subjected to a predetermined alignment treatment is provided. Upper substrate 5
A retardation plate 52 is provided on the front surface side of 1, and a polarizing plate 54 is provided on the front surface side of the retardation plate 52. The two substrates 41 and 51 are adhered to each other via a frame-shaped sealing material (not shown). For example, a nematic liquid crystal having a positive dielectric anisotropy is formed in a region surrounded by the two substrates 41 and 51 and the sealing material. 56 is twist-oriented by the alignment films 59 and 60 and is enclosed.

The alignment direction of liquid crystal molecules on the surface of the alignment film 59 of the upper substrate 51 of the liquid crystal display panel 31 and the polarizing plate 5
The transmission axis directions of 3 and 54 are set with the orientation direction of the liquid crystal molecules on the surface of the orientation film 60 of the lower substrate 41 of the liquid crystal display panel 31 as the azimuth angle of 0 °, and this direction is set as a reference. The alignment direction of the liquid crystal molecules on the upper substrate 51 of the liquid crystal display panel 31 is, for example, counterclockwise when viewed from above, that is, from the observation side with respect to the alignment direction of the liquid crystal molecules on the lower substrate 41, that is, the direction of azimuth angle 0 °. Almost 90 °
The liquid crystal molecules are displaced, and the liquid crystal molecules are twist-aligned between the substrates 41 and 51 at a twist angle of approximately 90 °.

Further, the transmission axis of the polarizing plate 54 is in a direction of 30 ° when viewed from the observation side, that is, the surface side with respect to the direction of azimuth angle of 0 °, and the transmission axis of the polarizing plate 53 is observed in the direction of azimuth angle of 0 °. It is in the direction of 50 ° when viewed from the side, and the slow axis of the retardation plate 52 is obliquely displaced from the transmission axis of the upper polarizing plate 54.

The liquid crystal display panel 31 is of a reflection type in which light incident from the upper polarizing plate 54 side is reflected by the reflecting plate 55 and displayed. The incident light is the upper polarizing plate 54 and the retardation plate 5.
2, the liquid crystal 56 and the lower polarizing plate 53 in order, and the reflecting plate 5
5, the reflected light is reflected by the lower polarizing plate 53 and the liquid crystal 5.
6, the phase difference plate 52 and the upper polarization plate 54 are sequentially emitted.

The slow axis of the retardation plate 52 is the upper polarizing plate 54.
Of the upper polarizing plate 5 because it is skewed with respect to the transmission axis of
When the linearly polarized light polarized through 4 passes through the retardation plate 52, it becomes elliptically polarized light which is different for each wavelength light due to its birefringence effect. The state is changed and emitted to the lower polarization plate 53, and only the polarized component of each wavelength light in the transmission axis direction of the lower polarization plate 53 is transmitted and reflected by the reflection plate 55.

The reflected light is reflected by the lower polarizing plate 53, the liquid crystal 56,
In the process of sequentially passing through the retardation plate 52 and the upper polarization plate 54, the polarization effect and the birefringence effect are exerted, and the light enters the upper polarization plate 54 again. The light that has entered the upper polarizing plate 54 has only the polarized component in the transmission axis direction thereof transmitted, and is colored according to the wavelength light having the transmitted polarized component. The birefringence effect of the liquid crystal 56 is
The light emitted from the liquid crystal display panel 31 changes to the voltage applied to the liquid crystal 56 because the spectrum distribution of the light emitted changes depending on the voltage applied to the liquid crystal display 6 and the difference in the birefringence effect. Accordingly, it is colored in a plurality of colors.

That is, in the liquid crystal display element 25, by applying a voltage between the pixel electrode 43 and the counter electrode 58, the arrangement of the liquid crystal molecules interposed therebetween is changed, and the liquid crystal 56 generated at that time is mixed. It is polarized by the refraction effect and the display color is controlled for each pixel to display a color image.

The image data generated by the CPU 11 and stored in the image memory 15 is composed of, for example, 6-bit data per pixel as shown in FIG. 2, with 2 bits being red (R) and 2 bits being green ( G) 2 bits represent the brightness of blue (B), and the composite color (designated display color) of these is the color that is originally desired to be displayed on each pixel.

Under the control of the CPU 11, the display control circuit 17 sequentially reads out the image data stored in the image memory 15 one scan line at a time and outputs it to the conversion table 19.
The conversion table 19 stores, for example, as shown in FIG. 3, voltage data corresponding to the image data in each storage area having the image data as an address, and is supplied from the display control circuit 17 under the control of the CPU 11. The voltage data stored in the position addressed by the image data to be read is read and output.

The storage data (voltage data) of the conversion table 19 is set as follows, for example. First, the characteristic of the liquid crystal display element 25 (the characteristic of the change in the display color of the pixel depending on the applied voltage) is obtained, for example, as shown in the RGB color space of FIG. That is, when a voltage of 0 V to 5 V is applied between the pixel electrode 43 of the liquid crystal display panel 31 and the counter electrode 58, the display of the pixel changes as indicated by the arrow. Next, the eight voltages V0 to V output from the voltage generation circuit 21.
Eight display colors when 7 is applied to the liquid crystal are obtained.

Next, with respect to each of 64 (2 ² × 2 ² × 2 ² ) colors defined by data of 2 bits for each of RGB and 6 bits in total, the corresponding or the closest approximation is made out of the display colors of 8 colors. A display color is obtained, and selection data for selecting a voltage corresponding to this display color is set in the corresponding storage area. When selecting a similar color, for example, in FIG.
As shown in, the displayable color at the shortest distance in the RGB color space is selected, and the voltage data corresponding to this color is set in the corresponding storage area.

The voltage generation circuit 21 is composed of a resistance division circuit, a capacitance division circuit, etc., for example, generates eight kinds of voltages V0 to V7 from 0V to 5V, and the multiplexer 23.
Supply to. The multiplexer 23 uses the conversion table 19
The 3-bit selection data supplied from the control terminal is received by the control terminal, and according to the selection data, one of the eight voltages V0 to V7 supplied from the voltage generation circuit 21 is selected and output to the output end. Under the control of the CPU 11, the multiplexer 23 outputs a signal of a predetermined horizontal sync level during each horizontal sync period. Therefore, the analog video signal output from the multiplexer 23 has a waveform as shown in FIG.

The column driver 33 samples the analog video signal for one line supplied from the multiplexer 23 and outputs the video signal sampled one horizontal scanning period before to the data line 49. Row driver 35
Applies a gate pulse to the gate line 47 sequentially according to a timing signal from the CPU 11. TFT4 connected to a gate line 47 to which a gate pulse is applied
5 is turned on, and the voltage (writing voltage) corresponding to the display color is applied from the data line 49 to the pixel electrode 43 connected to the turned-on TFT 45.

The row driver 35 turns off the gate pulse immediately before the voltage applied to the data line 49 is switched. Then, the TFT 45 is turned off, and the voltage applied until then is held in the capacitance formed by the pixel electrode 43, the counter electrode 58, and the liquid crystal 56 therebetween. As a result, the alignment state of the liquid crystal molecules is maintained in a desired state during the non-selection period, and a desired display color is maintained.

Next, the operation of the liquid crystal display device and its drive circuit shown in FIG. 1 will be described. The CPU 11 processes the program stored in the program memory 13, and the image memory 1
Image data defining an image to be displayed in 5 is appropriately written. The image data is data indicating the color to be displayed, and C
At the stage of creating a program executed by the PU 11, it is not necessary to have knowledge of the characteristics of the liquid crystal display element to be used, and it is not necessary to consider the characteristics in particular. Therefore, the programmer can create a program considering only the operation of the CPU 11 and the color of the image to be displayed.

The image data written in the image memory 15 by the CPU 11 is read by the display control circuit 17 for each scanning line in pixel units (6 bit units) and sequentially supplied to the address terminals of the conversion table 19. An address, that is, 3-bit selection data corresponding to the image data is stored at a position addressed by the image data of the conversion table 19, and the selection data is read and supplied to the multiplexer 23.

The multiplexer 23 selects the voltage supplied from the voltage generation circuit 21 according to the 3-bit selection data sequentially supplied from the conversion table 19 and outputs it as an analog video signal as shown in FIG. Column driver 3
3 samples the video signal for one line supplied from the multiplexer 23, and outputs it to the data line 49 in the next horizontal scanning period. The row driver 35 is a CPU
According to the timing signal from 11, the gate line 47
A pixel pulse 43 is sequentially selected (scanned) by sequentially applying a gate pulse to the pixel electrode 43 of the selected row.
A voltage corresponding to the display color is applied to the pixel via the data line 49 and the TFT 45. This voltage is, as mentioned above,
The voltage may be a voltage corresponding to the color originally desired to be displayed, or may be a voltage for displaying a color similar to the color originally desired to be displayed.

The row driver 35 turns off the gate pulse, turns off the TFT 45 immediately before the voltage applied to the data line 49 is switched, and turns off the pixel electrode 43 and the counter electrode 5.
The write voltage is held in the capacitance formed by 8 and the liquid crystal 56 between them. Therefore, the alignment state of the liquid crystal molecules is maintained in a desired state during the non-selection period, the desired birefringence is maintained, and the display color is maintained.

By repeating such operations in sequence, an image substantially equal to the image defined by the image data stored in the image memory 15 is displayed on the liquid crystal display element 25.

As described above, according to this embodiment,
When creating the program stored in the program memory 13, it is not necessary to consider the "applied voltage-display color" characteristic of the liquid crystal display element 25, and the display program can be created by only considering the color image to be displayed. , It becomes easy to create a program. Further, even when the liquid crystal display elements 25 having different characteristics are used, it is only necessary to adjust the voltage output from the voltage generation circuit 21 according to the characteristics,
Any color image can be created without modifying the display program itself.

The output voltage V0 to V7 can be made variable by configuring the voltage generation circuit 21 by a resistance division circuit using a variable resistance as shown in FIG. 7, for example. Further, the output voltage can be made variable even if it is configured by a capacitance division circuit using a variable capacitance. By arranging a knob (volume) VS for varying the voltage, for example, on the side surface of the liquid crystal display element 25 as shown in FIG.
As shown in FIG. 9, the user can adjust the display color by adjusting the voltage applied to the pixel electrode 43.

In the above embodiment, the contents of the conversion table 19 are set based on the relationship between the applied voltage and the display color on the RGB chromaticity diagram, but the locus of the display color on the CIE chromaticity diagram shown in FIG. The contents of the conversion table 19 may be set based on this. Also in this case, for colors that cannot be displayed, selection data for selecting a voltage that can display the closest displayable color on the chromaticity diagram is set. Alternatively, as shown in FIG. 11, the chromaticity diagram is radially divided with a white point as a reference, and the colors belonging to each divided area are replaced by the displayable color in the divided area. May be.

In the above embodiment, the table is used as the simplest example of converting the image data into the selected data.
For example, the applied voltage-display color characteristics shown in FIG. 3 or 10 may be stored in the form of a function, and the calculation may be performed every time the image data is supplied to obtain the selection data. Further, in the above-described embodiment, the image data has 6 bits of 2 bits for each of RGB, the voltage data has 3 bits, and the voltage applied to the liquid crystal has 8 steps, but these values are arbitrary.

In the liquid crystal display element in the above-mentioned embodiment, nematic liquid crystal having a positive dielectric anisotropy was twisted and used in the liquid crystal cell. However, the present invention is directed to a vertical molecular alignment (DAP) type using a cell in which liquid crystal molecules are homeotropically aligned, a parallel molecular alignment (homogeneous) type using a cell in which liquid crystal molecules are arranged in a twist-free homogeneous state, and a liquid crystal molecule. A hybrid molecular array (HAN) type cell using a hybrid molecular array cell in which the array is vertical on one substrate surface, parallel on the other substrate surface, and the array continuously changes between both substrates, or The present invention can be applied to various display elements such as a liquid crystal alignment mode type which uses a cell having a liquid crystal layer in which liquid crystal molecules change between splay alignment and bend alignment depending on a voltage. Further, in the above embodiment, the retardation plate was used, but depending on the arrangement of liquid crystal molecules,
It may be removed as appropriate. Further, the present invention is applicable not only to the reflective type but also to a transmissive type liquid crystal display element.

[0041]

As described above, according to the present invention, the designated display color (designated display color) is automatically converted into the corresponding voltage, so that an appropriate color image is displayed on the liquid crystal display element. Can be made. Also, even if a color that cannot be displayed by the liquid crystal display device is specified, an approximate displayable color is selected and automatically converted to a voltage corresponding to that color, so an appropriate color display image can be obtained. You can Further, when liquid crystal display elements having different characteristics are used, an arbitrary color image can be displayed without modifying the display program body simply by changing the voltage generated according to the characteristics of the liquid crystal display element. Also, by making the generated voltage variable, the user can control the display color.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of image data stored in an image memory shown in FIG.

FIG. 3 is a diagram showing a configuration example of a conversion table shown in FIG.

FIG. 4 is an RGB chromaticity diagram showing an example of a relationship between an applied voltage of a liquid crystal display element and a display color.

FIG. 5 is a diagram illustrating a method of setting voltage data corresponding to a color that cannot be displayed.

FIG. 6 is a diagram showing an example of an output signal of a D / A converter.

FIG. 7 is a circuit diagram showing a configuration example of a voltage generation circuit.

FIG. 8 is a diagram showing an example in which a volume switch for adjusting a voltage generated by a voltage generation circuit is arranged on a side surface of a liquid crystal display element.

FIG. 9 is a diagram showing how a display color is changed by operating a volume switch.

FIG. 10 is a CIE chromaticity diagram showing an example of a relationship between an applied voltage of a liquid crystal display element and a display color.

FIG. 11 is a diagram illustrating a method of setting voltage data corresponding to a color that cannot be displayed.

FIG. 12 is a cross-sectional view of a liquid crystal display panel.

[Explanation of symbols]

11 ... CPU, 13 ... Program memory, 15 ... Image memory, 17 ... Display control circuit, 19 ... Conversion table, 21 ... Voltage generation circuit, 23 ... Multiplexer, 2
5 ... Liquid crystal display element, 31 ... Liquid crystal display panel, 33 ...
Column driver, 35 ... Row driver, 41 ... Substrate, 43 ...
.Pixel electrode, 45 ... Thin film transistor (TFT), 47
... Gate line, 49 ... Data line, 51 ... Substrate, 52 ... Phase difference plate, 53 ... Polarizing plate, 54 ... Polarizing plate, 55 ... Reflecting plate, 56 ... ..Liquid crystal, 58 ... Counter electrode,
59 ... Alignment film, 60 ... Alignment film

Claims (10)

[Claims] 1. A liquid crystal display element for displaying a plurality of colors according to an applied voltage, a color instructing means for instructing a designated display color of the liquid crystal display element, an applied voltage to the liquid crystal display element and the instructed display color. And a conversion unit that stores the relationship between the display color determined based on the relationship between the display color and the corresponding voltage value, and outputs the voltage selection data corresponding to the designated display color designated by the color designating unit. An image is generated by selecting a voltage generation unit that outputs a generated voltage and a voltage corresponding to the voltage selection data output by the conversion unit from the generated voltage of the voltage generation unit, and supplying the selected voltage to the liquid crystal display element. A liquid crystal display device, comprising: a supply unit for displaying. 2. The voltage generating means is composed of a voltage dividing circuit that outputs different generated voltages, and the supplying means outputs the voltage output by the voltage dividing circuit according to the voltage selection data output by the converting means. The liquid crystal display device according to claim 1, further comprising: a multiplexer to be selected, and a driving unit that supplies an output voltage of the multiplexer to the liquid crystal display element. 3. The conversion means outputs voltage selection data corresponding to a displayable color close to the designated display color with respect to the designated display color designated by the color designating means. Item 3. The liquid crystal display device according to item 1 or 2. 4. The voltage generating means comprises a varying means for varying the voltage value of the generated voltage.
2. The liquid crystal display device according to 2 or 3. 5. The liquid crystal according to claim 1, wherein the color designating means designates a plurality of colors having different wavelength bands for displaying the designated display color. Display device. 6. The liquid crystal display device according to claim 1, wherein the liquid crystal display element performs display by an optical effect by controlling birefringence. 7. A color instructing means for outputting color data for instructing a display color on a pixel-by-pixel basis, a converting means for converting the color data into selection data for selecting a corresponding voltage, and generating a plurality of voltages. Voltage generating means, selecting means for selecting one of the voltages generated by the voltage generating means in accordance with the selection data output by the converting means, and birefringence control of the voltage selected by the selecting means. A liquid crystal display device comprising: a driving unit configured to display a color image on the liquid crystal display element by supplying and driving the liquid crystal display element of the mold. 8. A color instructing step for instructing a display color, a converting step for converting the designated display color instructed by the color instructing step into selection data for selecting a corresponding voltage, and generating a plurality of voltages. A voltage generating step, a selecting step of selecting a voltage corresponding to the selection data from a plurality of voltages generated by the voltage generating step in accordance with the selection data, and applying the voltage selected by the selecting step. A driving method of supplying a liquid crystal display device that displays a color according to a voltage to drive the liquid crystal display device to display a color image on the liquid crystal display device, and driving the liquid crystal display device. 9. The selection step includes a voltage generation step of generating a plurality of voltages, and a voltage corresponding to the selection data is selected from a plurality of voltages generated by the voltage generation step according to the selection data. 9. The method for driving a liquid crystal display device according to claim 8, further comprising: 10. The method of driving a liquid crystal display device according to claim 8, wherein the voltage generating step includes a step of converting a generated voltage.