JPH11326876A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display information while keeping fixed color reproducibility in a reflective type STN liquid crystal display independent of color components of external light. SOLUTION: A means for detection of color components of external light 101 is provided to detect the color components of the external light. When each color display signal constituting each pixel of the image is inputted, red, green and blue FRC gradation controlling means 102, 103 and 104 control the gradation corresponding to a bit of each display signal by using frame rate controlling. In this case, gradation correction corresponding to the color component ratio of a color component detecting signal 105 is conducted. A means for controlling a liquid crystal signal 113 rearranges gradation-controlled display signals into matrix type and supplies liquid crystal cell display data 118 to a means of data side driving 118. A means of scanning side driving 117 generates scanning pulses based on timing signals for liquid crystal display 115 and gives them to respective scanning electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type S for displaying information without being affected by a color component of external light.
The present invention relates to a liquid crystal display device having a TN structure.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been widely used as display displays, such as personal computers and monitors, because of their dramatic increase in display capacity, characteristics of thin and light weight and low power consumption. Among them, reflective super twisted nematic (hereinafter referred to as reflective ST)
N) does not require a backlight, and can be driven with lower power consumption than the transmissive type.

A conventional reflection type STN liquid crystal display device will be described with reference to FIG. FIG. 5 is a configuration diagram of a reflective STN liquid crystal display device 500 using a frame rate control (hereinafter, referred to as FRC) gradation control method.

[0004] The FRC gradation control means 501 includes a display timing signal 106, a red display signal 107, and a green display signal 1.
08, a blue display signal 109 is input, FRC gradation control described later is performed, and a liquid crystal display signal 502 is output. Each of these display signals 107, 108, and 109 is composed of a plurality of bits to indicate a gradation value (luminance value).
On the other hand, the liquid crystal display signal 502 is composed of one bit. The liquid crystal signal control means 503 receives the liquid crystal display signal 502 that has been subjected to the FRC gradation control, and
Liquid crystal cell display data 504 in synchronization with the timing 06.
And a circuit for outputting a timing signal 115 for liquid crystal display.

The matrix liquid crystal panel 116 is a PM type liquid crystal panel using STN liquid crystal, and has a large number of scanning electrodes and a large number of data electrodes formed in a matrix.
The scanning-side driving means 117 outputs the timing signal 1 for liquid crystal display.
15, a scan pulse is given to each scan electrode. The data-side driving unit 118 is a circuit that generates a data pulse based on the liquid crystal cell display data 504 and the liquid crystal display timing signal 115 and applies the data pulse to each data electrode of the matrix liquid crystal panel 116. Each data pulse controls the molecular orientation of each liquid crystal cell (pixel) by its effective value voltage, and changes the reflectance of each pixel.

[0006] The liquid crystal display device 500 configured as described above.
Will be described. Red display signal 1 of multiple bits
07, the green display signal 108 and the blue display signal 109 together with the display timing signal 106
1 is input. The FRC gradation control unit 501 converts a gradation value represented by a plurality of bits into a display signal that can be represented by one bit (binary) in the input red, green, and blue display signals. In this conversion, assuming that one screen writing time is one frame period, the gradation (bit value) of the display signal
Is performed by controlling on / off of voltage application to each liquid crystal cell of the matrix liquid crystal panel 116 for each frame in units of a plurality of frames.

[0007] The liquid crystal display signal 502 converted by the FRC gradation control means 501 is input to the liquid crystal display control means 503 and rearranged for liquid crystal display. The rearranged display signals are transferred to the data driving unit 118 as liquid crystal cell display data 504. The data driving means 118 applies a data pulse to each data electrode of the matrix liquid crystal panel 116.

On the other hand, the display timing signal 106 is also input to the liquid crystal display control means 503, and is converted into a liquid crystal display timing signal 115. The liquid crystal display timing signal 115 is transmitted to the data driving unit 118 and the scanning driving unit 1.
17 is transferred. The scanning side driving means 117 sequentially selects the scanning electrodes of the matrix liquid crystal panel 116 and applies a scanning pulse.

[0009]

However, in the above-mentioned reflection type liquid crystal display device, the color reproducibility of the reflection type liquid crystal panel differs depending on the color components of the outdoor light and the illumination light. For example, the color temperature differs depending on the sunshine time, even in an outdoor environment where outdoor light is received. Furthermore, in various types of indoor lighting, the center wavelength differs depending on the type of the illumination light source. In such an environment, when an image on a reflective liquid crystal panel is viewed using outdoor light or illumination light (hereinafter, both are referred to as external light), it can be said that the image is always displayed with constant color reproducibility. Did not.

In the FRC gradation control means 501 shown in FIG. 5, the red display signal 107,
Since the frame thinning rate is determined in accordance with the gradation values of the green display signal 108 and the blue display signal 109, the color reproducibility of the matrix liquid crystal panel 116 is reduced when the balance of the color components of the external light is lost. It changes from the original image.
Under such external light, the display image quality is significantly reduced,
No countermeasures have been taken in conventional liquid crystal display devices.

In the above description, the FRC gradation control means has been described as the gradation control means of the liquid crystal display device. However, as another gradation control means, pulse width modulation (hereinafter referred to as PWM) gradation control means has been described. A similar problem occurs even if the means is used.

The present invention has been made in view of such a conventional problem, and it is possible to always display information with constant color reproducibility under external light having any color components. It is an object of the present invention to realize a reflective STN liquid crystal display device that can be used.

[0013]

In order to achieve the above object, according to the first aspect of the present invention, a display signal of three colors composed of a plurality of bits is inputted as a gradation value of each pixel, and a liquid crystal is inputted. A liquid crystal display device for displaying information on a panel, comprising: an external light color component detecting means for detecting a color component of external light; and a liquid crystal display device for externally inputting a color display signal of each pixel based on its gradation value. A display signal gradation control means for converting a gradation value of the liquid crystal display signal based on a component ratio of each color output from the external light color component detection means, and a scanning electrode and a data electrode. The formed reflective matrix liquid crystal panel, the liquid crystal signal control means for rearranging the liquid crystal display signal output from the display signal gradation control means to the pixel array of the reflective matrix liquid crystal panel, and the output from the liquid crystal signal control means. Liquid crystal Data-side driving means for providing display data to the data electrodes of the reflective matrix liquid crystal panel, and converting a timing signal for liquid crystal display output from the liquid crystal signal control means into a scanning pulse to scan the reflective matrix liquid crystal panel. Scanning-side driving means for sequentially outputting to the electrodes.

According to a second aspect of the present invention, there is provided a liquid crystal display device for displaying information on a liquid crystal panel by inputting a display signal of three colors composed of a plurality of bits as a gradation value of each pixel. An external light color component detecting means for detecting a color component of external light applied to the panel, and converting a red display signal of each pixel input from the outside into a liquid crystal display signal based on the gradation value, and A red display signal gradation control unit that corrects a gradation value of the liquid crystal display signal based on a red component ratio in a color component detection signal output from the light color component detection unit; The green display signal is converted into a liquid crystal display signal based on the gradation value, and the gradation of the liquid crystal display signal is calculated based on the green component ratio in the color component detection signal output from the external light color component detection means. Green table to correct values A signal gradation control unit, and converts a blue display signal of each pixel input from the outside into a liquid crystal display signal based on the gradation value, and a color component detection signal output from the external light color component detection unit. A blue display signal gradation control unit for correcting a gradation value of the liquid crystal display signal based on a blue component ratio; a red liquid crystal display signal output from the red display signal gradation control unit; The green liquid crystal display signal output from the tone control means and the blue liquid crystal display signal output from the blue display signal gradation control means are respectively input and rearranged into the pixel arrangement of the liquid crystal panel to create liquid crystal cell display data. A liquid crystal signal control means for generating a liquid crystal display timing signal for instructing an output timing to each pixel of the liquid crystal panel; and a scanning electrode and a data electrode formed in a lattice. A reflective matrix liquid crystal panel in which liquid crystal responding to an effective value voltage applied between the two electrodes is sandwiched; and a liquid crystal cell display data output from the liquid crystal signal control means is converted into a voltage, and the reflective matrix is converted. A data-side driving means for applying to a data electrode of the liquid crystal panel; and a scanning side for converting a liquid crystal display timing signal output from the liquid crystal signal control means into a scanning pulse and sequentially outputting the scanning pulse to the scanning electrode of the reflective matrix liquid crystal panel. And a driving means.

According to a third aspect of the present invention, there is provided a liquid crystal display device for inputting a display signal of three colors composed of a plurality of bits as a gradation value of each pixel and displaying information on a liquid crystal panel. The input red, green, and blue display signals of each pixel are rearranged into a pixel array of the liquid crystal panel to generate liquid crystal cell display signals of each color, and output timing to each pixel of the liquid crystal panel. Liquid crystal signal control means for generating a liquid crystal display timing signal for instructing the liquid crystal panel, external light color component detection means for detecting a color component of external light applied to the liquid crystal panel, and red output from the liquid crystal signal control means. The liquid crystal cell display signal is converted into red liquid crystal cell display data based on the gradation value, and based on the red component ratio in the color component detection signal output from the external light color component detection means. Te, a red display signal gradation control means for correcting the gradation value of the red liquid crystal cell display data,
The green liquid crystal cell display signal output from the liquid crystal signal control means is converted into green liquid crystal cell display data based on the gradation value, and the green color in the color component detection signal output from the external light color component detection means. Based on the component ratio of
A green display signal gradation control unit for correcting a gradation value of the green liquid crystal cell display data; and a blue liquid crystal cell display signal output from the liquid crystal signal control unit, based on the gradation value. And a blue display signal gradation control means for correcting a gradation value of the blue liquid crystal cell display data based on a blue component ratio in a color component detection signal output from the external light color component detection means. A reflective matrix liquid crystal panel in which a scanning electrode and a data electrode are formed in a lattice shape, and a liquid crystal responsive to an effective value voltage applied between the two electrodes is sandwiched; and the red display signal gradation control means; Each of the liquid crystal cell display data output from the green display signal gradation control means and the blue display signal gradation control means is subjected to voltage conversion, and data to be supplied to the data electrodes of the reflective matrix liquid crystal panel. Side driving means, and scanning side driving means for converting a liquid crystal display timing signal output from the liquid crystal signal control means into a scanning pulse and sequentially outputting the scanning pulse to a scanning electrode of the reflective matrix liquid crystal panel. It is a feature.

According to a fourth aspect of the present invention, in the liquid crystal display device of the second aspect, the method of controlling the gradation of each pixel is such that the reflectance of the pixel of the liquid crystal panel is changed in frame units, When the frame rate control is performed in units of a plurality of frames, the red display signal gradation control means, the green display signal gradation control means, and the blue display signal gradation control means control the red, green, and blue display signals. And converting the gradation value of each pixel into a liquid crystal display signal using the frame rate control, and based on the color component ratio in the color component detection signal output from the external light color component detection means. The feature is to correct the tone value of the signal.

According to a fifth aspect of the present invention, in the liquid crystal display device of the third aspect, the method of controlling the gradation of each pixel is changed by changing the reflectance of the pixel of the liquid crystal panel in frame units, When the frame rate control is performed in units of a plurality of frames, the red display signal gradation control means, the green display signal gradation control means, and the blue display signal gradation control means are output from the liquid crystal signal control means. The liquid crystal cell display signal of each color is converted into liquid crystal cell display data using the frame rate control based on the gradation value, and the color component ratio in the color component detection signal output from the external light color component detection means is calculated. The tone value of the liquid crystal cell display data is corrected based on the correction value.

According to a sixth aspect of the present invention, in the liquid crystal display device according to the third aspect, a method of controlling the gradation of each pixel includes a method of controlling the reflectance of the pixel of the liquid crystal panel by applying a data pulse applied to each frame. When performing the PWM control in which the pulse width is controlled by the following pulse width, the red display signal gradation control means, the green display signal gradation control means, and the blue display signal gradation control means The liquid crystal cell display signal is converted into liquid crystal cell display data using the PWM control based on the gradation value, and based on the color component ratio in the color component detection signal output from the external light color component detection means, It is characterized in that the gradation value of the liquid crystal cell display data is corrected.

According to a seventh aspect of the present invention, in the liquid crystal display device of the third aspect, the red display signal gradation control means, the green display signal gradation control means, the blue display signal gradation control means, A signal electrode drive unit in which data-side drive means are integrated on the same substrate is incorporated in the reflective matrix liquid crystal panel.

[0020]

(Embodiment 1) A reflective STN liquid crystal display device according to Embodiment 1 of the present invention will be described. FIG. 1 is a block diagram showing a configuration of a reflective STN liquid crystal display device 100 according to the present embodiment. Blocks and signal names having the same contents as those of the conventional example will be described with the same reference numerals. This liquid crystal display device 100 is different from the configuration of the conventional liquid crystal display device in that the external light color component detection means 101, the red FRC gradation control means 102, the green FRC gradation control means 103, and the blue FR
C gradation control means 104 is provided.

The external light color component detecting means 101 is a detecting means for detecting a color component of external light for each of red, green and blue. The external light color component detection means 101 is composed of, for example, red, green, and blue photoelectric conversion elements attached to a housing of a matrix liquid crystal panel, and outputs a color component detection signal 105 indicating a component ratio of each color. The color component detection signal 105 output from the external light color component detection unit 101 and the display timing signal 106 input from the outside correspond to a red FRC gradation control unit 102, a green FRC gradation control unit 103, and a blue FRC gradation control unit 103, respectively.
It is provided to RC gradation control means 104.

The red FRC gradation control means 102 converts the red display signal 107 of each pixel input from the outside into a red liquid crystal display signal using FRC based on the gradation value, and a color component detection signal 105. Is a control unit that corrects the gradation of the red liquid crystal display signal by FRC based on the red component ratio of the red liquid crystal display signal to generate a red liquid crystal display signal 110. Similarly, the green FRC gradation control unit 103 converts the green display signal 108 of each pixel, which is input from the outside, into an F based on the gradation value.
A control unit that converts the green liquid crystal display signal into a green liquid crystal display signal using RC, corrects the gradation of the green liquid crystal display signal by FRC based on the green component ratio of the color component detection signal 105, and generates a green liquid crystal display signal 111. is there. Further, the blue FRC gradation control means 104 converts the blue display signal 109 of each pixel input from the outside into a blue liquid crystal display signal using the FRC based on the gradation value, and the color component detection signal 10.
Control means for correcting the gradation of the blue liquid crystal display signal by FRC based on the blue component ratio of No. 5 and generating the blue liquid crystal display signal 112. The gradation control for any of the color display signals is performed in synchronization with the display timing signal 106.

The liquid crystal signal control means 113 includes a red liquid crystal display signal 110, a green liquid crystal display signal 111,
A blue liquid crystal display signal 112 is input, and the liquid crystal cell display data 11 is synchronized with the timing of the display timing signal 106.
4 and a circuit for generating a timing signal 115 for liquid crystal display.

The matrix liquid crystal panel 116 is a reflection type liquid crystal panel using STN liquid crystal, in which a large number of scanning electrodes and a large number of data electrodes are formed in a matrix. The scanning-side driving means 117 outputs the timing signal 11 for liquid crystal display.
5, a scan pulse is sequentially applied to each scan electrode. The data side driving means 118 receives the liquid crystal cell display data 114 and outputs the liquid crystal display timing signal 11.
5 is a circuit for generating a data pulse based on the data pulse No. 5 and applying the data pulse to each data electrode of the matrix liquid crystal panel 116. Each data pulse controls the molecular orientation of each liquid crystal cell (pixel) by its effective value, and changes the reflectance of each pixel.

The operation of the reflection type STN liquid crystal display device 100 configured as described above will be described. The red display signal 107 composed of a plurality of bits is input to the red FRC gradation control means 102 together with the display timing signal 106. Also, the green display signal 108 of a plurality of bits is supplied to the green FRC gradation control unit 10 together with the display timing signal 106.
3 is input. Furthermore, a plurality of bits of the blue display signal 10
9 is input to the blue FRC gradation control means 104 together with the display timing signal 106.

When the liquid crystal display device 100 is used indoors, room illumination light is incident on the photoelectric conversion element of the external light color component detecting means 101. When the light source of the indoor lighting is a fluorescent lamp, there is little red component. Therefore, the level of the red component in the color component detection signal 105 of the external light color component detection means 101 is lower than the level of the green component and the blue component. Also, the liquid crystal display device 100
Is used outdoors during the day or under natural light emitted from a window, the color balance is often maintained, and the red, green, and blue components in the color component detection signal 105 are often used. Are almost equal.

Red FRC gradation control means 102, green FR
C gradation control means 103, blue FRC gradation control means 104
Are the input red display signal 107 and green display signal 10
8. The display signal is converted so that the gray scale value represented by a plurality of bits in the blue display signal 109 can be displayed by one bit (binary). That is, the frame thinning rate of each pixel is determined according to the bit value of the display signal, and ON / OFF of voltage application to the matrix liquid crystal panel 116 is controlled.

At this time, the control of the voltage application to the matrix liquid crystal panel 116 for the gradation value represented by a plurality of bits is not fixed by the red, green and blue display signals, but is detected by the external light color component detection means 101. Red, based on the color component
Performed individually for green and blue display signals. For example, when the outside light has a large red component, the red display signal 107 is converted so as to have lower luminance than the conversion values of the green display signal 108 and the blue display signal 109. In this way, the display signal of the same color as the color that is the main component of the external light is controlled on a frame-by-frame basis so that the luminance becomes low.

The red liquid crystal display signal 110 converted by the red FRC gradation control means 102 and the green FRC gradation control means 103
And the blue liquid crystal display signal 112 converted by the blue FRC gradation control means 104 are:
Each is input to the liquid crystal display control means 113. Then, the data is rearranged in a matrix for liquid crystal display, and transferred to the data side driving means 118 as liquid crystal cell display data 114 in units of one horizontal scan (1H).

On the other hand, the display timing signal 106 is also input to the liquid crystal signal control means 113 and converted for liquid crystal display.
It is output to the data-side driving unit 118 and the scanning-side driving unit 117 as a liquid crystal display timing signal 115.

The data driving means 118 applies a data pulse to each data electrode of the matrix liquid crystal panel 116. The scanning driver 117 sequentially selects the scanning electrodes of the matrix liquid crystal panel 116 based on the liquid crystal display timing signal 115 and applies a scanning pulse. In this way, the same information such as color images and characters as the information source is displayed.

The above-mentioned reflection type STN liquid crystal display device 100
When information is displayed by using, information can always be displayed with constant color reproducibility under external light having any color component. For this reason, it is possible to realize a reflective STN liquid crystal display device having high image quality without being affected by the color component of external light.

(Embodiment 2) Next, a reflective STN liquid crystal display device according to Embodiment 2 of the present invention will be described. FIG. 2 is a block diagram showing a configuration of a reflective STN liquid crystal display device 200 according to the present embodiment. Note that blocks and signal names having the same contents as those of the conventional example and the first embodiment are described with the same reference numerals. This liquid crystal display device 2
00 is different from the liquid crystal display device of the first embodiment in that PWM (pulse width modulation) is used for gradation control of a display signal, and PWM gradation control means for each color is provided at a subsequent stage of the liquid crystal signal control means. ing.

The external light color component detecting means 101 is a detecting means for detecting a color component of external light, as in the first embodiment.
The color component detection signal 105 output from the external light color component detection unit 101 is output by a red PWM gradation control unit 201 and a green PW
M gradation control means 202, blue PWM gradation control means 203
Given to.

The liquid crystal signal control means 204 comprises a display timing signal 106, a red display signal 107, a green display signal 10
8. A circuit which receives the blue display signal 109 and rearranges the display signals for liquid crystal display in synchronization with the timing of the display timing signal 106. The display signals rearranged here are called a red liquid crystal cell display signal 205, a green liquid crystal cell display signal 206, and a blue liquid crystal cell display signal 207. These liquid crystal cell display signals are composed of a plurality of bits as in the case of the input of the liquid crystal signal control means 204. The display timing signal 106 is also converted into a liquid crystal display timing signal 115 by the liquid crystal signal control means 204.

The red PWM gradation control means 201 performs pulse width modulation in accordance with the gradation value of the input red liquid crystal cell display signal 205 and generates a pulse based on the red component ratio of the color component detection signal 105. This is control means for correcting the width and generating red liquid crystal cell display data 208. Similarly, the green PWM gradation control unit 202 performs pulse width modulation in accordance with the gradation value of the input green liquid crystal cell display signal 206, and performs pulse width modulation based on the green component ratio of the color component detection signal 105. The width is corrected, and the green liquid crystal cell display data 209 is corrected.
Is a control means for generating Further, the blue PWM gradation control unit 203 performs pulse width modulation in accordance with the gradation value of the input blue liquid crystal cell display signal 207, and changes the pulse width based on the blue component ratio of the color component detection signal 105. It is a control unit that corrects and generates blue liquid crystal cell display data 210.

The PWM data voltage generation means 211 amplifies the voltage of the inputted red liquid crystal cell display data 208, green liquid crystal cell display data 209, and blue liquid crystal cell display data 210, and inputs the effective voltage applied to each liquid crystal cell. This is a voltage generating means for generating a PWM pulse for data so as to correspond to the gradation value.

The matrix liquid crystal panel 116 is a reflection type liquid crystal panel using STN liquid crystal, and has a large number of scanning electrodes and a large number of data electrodes formed in a matrix. The scanning-side driving means 117 outputs the timing signal 11 for liquid crystal display.
5, a scan pulse is sequentially applied to each scan electrode. Each data electrode of the matrix liquid crystal panel 116 is driven by a data PWM pulse output from the PWM data voltage generation means 211.
Here, the PWM data voltage generation means 211 has the function of the data side driving means as in the first embodiment.

The operation of the thus configured reflective STN liquid crystal display device 200 will be described. A red display signal 107, a green display signal 108,
The blue display signal 109 is input to the liquid crystal signal control unit 204 together with the display timing signal 106. The liquid crystal signal control means 204 converts the display timing signal 106 into a liquid crystal display timing signal 115 and rearranges the red display signal 107, the green display signal 108, and the blue display signal 109 into a matrix for liquid crystal display. A liquid crystal cell display signal 205, a green liquid crystal cell display signal 206, and a blue liquid crystal cell display signal 207 are respectively generated.

The external light color component detecting means 101 detects a color component of external light in an environment where the liquid crystal display device 200 is used, and outputs a color component detection signal 105 to the red PWM gradation control means 2.
01, green PWM gradation control means 202 and blue PWM gradation control means 203. Red PWM gradation control means 20
1 converts the gradation value of the input red liquid crystal cell display signal 205 into a pulse width, and generates red liquid crystal cell display data 208 for controlling the voltage application time to each liquid crystal cell of the matrix liquid crystal panel 116 every 1H. I do.

For example, the liquid crystal display device 200 under natural light
Is used, the red component of the color component detection signal 105 is
Since the level is the same as that of the other color components, the red PWM gradation control means 201 outputs the input red liquid crystal cell display signal 205
Pulse width conversion is performed to obtain a gradation value corresponding to only the bit value of. On the other hand, under external light with a large amount of red component, the red PWM gradation control unit 201 converts the conversion of the red liquid crystal cell display signal 205 to a value lower than the conversion values of the green and blue liquid crystal cell display signals. This is performed so that the brightness is obtained.
Thus, the red liquid crystal cell display data 208 corresponding to the red component ratio of the external light is generated.

The same operation is performed by the green PWM gradation control means 202 and the blue PWM gradation control means 203.
Since such a PWM gradation control means is provided in front of the PWM data voltage generation means 211, one input of the horizontal synchronizing signal as the liquid crystal display timing signal 115 allows all the data electrodes of the matrix liquid crystal panel 116 to be input. Can be given a data PWM pulse at the same time.

Red PWM gradation control means 201, green PWM
M gradation control means 202, blue PWM gradation control means 203
, Green liquid crystal cell display data 209, and blue liquid crystal cell display data 2
10 is input to the PWM data voltage generation means 211. These liquid crystal cell display data are converted into data PWM pulses in synchronization with the liquid crystal display timing signal 115. The conversion here is to voltage-amplify the input pulse, and the amplified data PWM pulse is
It is applied to each data electrode of the matrix liquid crystal panel 116.

On the other hand, the liquid crystal display timing signal 115 converted by the liquid crystal display control means 204 is also transferred to the scanning side driving means 117 and is converted into a scanning pulse. These scanning pulses are sequentially output to each scanning electrode of the matrix liquid crystal panel 116.

The above-mentioned reflective STN liquid crystal display device 200
When information is displayed by using, the information can be always displayed with constant color reproducibility by PWM gradation control under external light having any color component. For this reason, it is possible to realize a reflective STN liquid crystal display device having high image quality and little flicker without being affected by the color component of external light.

In the liquid crystal display device 200 of this embodiment, each PWM gradation control means is provided after the liquid crystal control means 204, but may be provided before the liquid crystal control means as shown in FIG. In this case, the number of signal lines of each PWM gradation control means and liquid crystal signal control means is significantly reduced as compared with the case of FIG. However, the respective PWM gradation control means and the PWM data voltage generation means are integrated, and the matrix liquid crystal panel 116
It is difficult to integrate them on a substrate.

(Embodiment 3) Next, a reflective STN liquid crystal display device according to Embodiment 3 of the present invention will be described. FIG. 3 is a block diagram showing a configuration of a reflective STN liquid crystal display device 300 according to the present embodiment. Note that blocks and signal names having the same contents as those in Embodiments 1 and 2 are described with the same reference numerals. This liquid crystal display device 300 is different from the liquid crystal display device of the first embodiment in that FRC gradation control means for performing gradation control of a display signal is integrated with a circuit portion for driving data electrodes of a matrix liquid crystal panel. It is characterized by the following. For this reason, FRC gradation control means for each color is provided downstream of the liquid crystal signal control means.

The external light color component detecting means 101 is a detecting means for detecting a color component of external light, as in the first and second embodiments. The color component detection signal 105 output from the external light color component detection unit 101 is output to a red FRC gradation control unit 301, a green FRC gradation control unit 302, and a blue FRC gradation control unit 3.
03.

The liquid crystal signal control means 204 comprises a display timing signal 106, a red display signal 107, a green display signal 10
8. A circuit which receives the blue display signal 109 and rearranges the display signals for liquid crystal display in synchronization with the timing of the display timing signal 106. The rearranged display signals are referred to as a red liquid crystal cell display signal 205, a green liquid crystal cell display signal 206, and a blue liquid crystal cell display signal 207. These display signals are composed of a plurality of bits as in the case of the input of the liquid crystal signal control means 204. The display timing signal 10
6 is also converted into a liquid crystal display timing signal 115 by the liquid crystal signal control means 204.

The red FRC gradation control means 301 is a control means for controlling the frame rate in accordance with the bit value of the input red liquid crystal cell display signal 205 and performing gradation control. The red FRC gradation control unit 301 corrects the frame rate based on the red component ratio of the color component detection signal 105, and generates red liquid crystal cell display data 304. Similarly, the green FRC gradation control means 302 controls the frame rate in accordance with the bit value of the input green liquid crystal cell display signal 206, and adjusts the frame rate based on the green component ratio of the color component detection signal 105. It is a control unit that corrects and generates green liquid crystal cell display data 305. Further blue FR
The C gradation control unit 303 controls the frame rate according to the bit value of the input blue liquid crystal cell display signal 207, corrects the frame rate based on the blue component ratio of the color component detection signal 105, Liquid crystal cell display data 306
Is a control means for generating

The display data control means 307 includes red liquid crystal cell display data 304, green liquid crystal cell display data 305,
Control means for inputting blue liquid crystal cell display data 306 and rearranging the liquid crystal cell display data in the arrangement order of the data electrodes of the matrix liquid crystal panel 116. The display data voltage generating means 308 amplifies the voltage of the liquid crystal cell display data of each color output from the display data control means 307 and generates a data FRC pulse so that the effective voltage applied to each liquid crystal cell corresponds to the input gradation value. Output means.

The matrix liquid crystal panel 116 is a reflection type liquid crystal panel using STN liquid crystal, and has many scanning electrodes and many data electrodes formed in a matrix. The scanning-side driving means 117 outputs the timing signal 11 for liquid crystal display.
5, a scan pulse is sequentially applied to each scan electrode. Each data electrode of the matrix liquid crystal panel 116 is driven by a data FRC pulse output from the display data voltage generating means 308.

In this embodiment, the red FRC gradation control means 301, the green FRC gradation control means 302, the blue FRC gradation control means 303, the display data control means 307, and the display data voltage indicated by dotted lines in FIG. Generating means 308,
Integrated as a hybrid IC, monolithic IC, or FPC board. These circuit groups are called a data electrode drive unit 309. Here, the display data control unit 307 and the display data voltage generation unit 308 have the same function as the data side driving unit as in the first embodiment.

The operation of the thus configured reflective STN liquid crystal display device 300 will be described. A red display signal 107, a green display signal 108,
The blue display signal 109 is input to the liquid crystal signal control unit 204 together with the display timing signal 106. The liquid crystal signal control means 204 converts the display timing signal 106 into a liquid crystal display timing signal 115 and rearranges the red display signal 107, the green display signal 108, and the blue display signal 109 into a matrix for liquid crystal display. A cell display signal 205, a green liquid crystal cell display signal 206, and a blue liquid crystal cell display signal 207 are generated.

The external light color component detecting means 101 detects a color component of external light in an environment where the liquid crystal display device 300 is used, and outputs a color component detection signal 105 to the red FRC gradation control means 3.
01, green FRC gradation control means 302 and blue FRC gradation control means 303. Red FRC gradation control means 30
In the input red liquid crystal cell display signal 205, a gray scale value represented by a plurality of bits is converted into a frame thinning ratio in synchronization with the liquid crystal display timing signal 115. Then, red liquid crystal cell display data 304 is generated as a signal for controlling on / off of voltage application to each liquid crystal cell of the matrix liquid crystal panel 116 on a frame basis.

For example, the liquid crystal display device 300 under natural light
Is used, the red component of the color component detection signal 105 is
Since the level is the same as that of the other color components, the red FRC gradation control means 301 outputs the inputted red liquid crystal cell display signal 205.
The frame thinning rate is determined in order to obtain a gradation value corresponding to only the bit value of the frame. On the other hand, under external light with a large amount of red component, the red FRC gradation control means 301 converts the conversion of the red liquid crystal cell display signal 205 to a value lower than the conversion values of the green and blue liquid crystal cell display signals. Brightness (low reflectance)
The frame thinning rate is determined so that Thus, the red liquid crystal cell display data 304 corresponding to the red component of the external light is generated.

The same operation is performed by the green FRC gradation control means 302 and the blue PWM gradation control means 303. Since such an FRC gradation control means is provided in front of the display data control means 307, all the data electrodes of the matrix liquid crystal panel 116 need only be input once as a liquid crystal display timing signal 115. , A data FRC pulse can be applied simultaneously.

Red FRC gradation control means 301, green FR
C gradation control means 302, blue FRC gradation control means 303
The red liquid crystal cell display data 304, the green liquid crystal cell display data 305, and the blue liquid crystal cell display data 3
06 is input to the display data control means 307 and rearranged in the arrangement order of the respective data electrodes of the matrix liquid crystal panel 116. Then, the display data voltage generating means 308
, Amplifies the voltage of the rearranged liquid crystal cell display data and applies it to each data electrode of the matrix liquid crystal panel 116.

On the other hand, the liquid crystal display timing signal 115 converted by the liquid crystal display control means 204 is also transferred to the scanning side driving means 117 and is converted into a scanning pulse. These scanning pulses are sequentially output to each scanning electrode of the matrix liquid crystal panel 116.

When information is displayed using the reflective STN liquid crystal display device 300 as described above, the display of information always maintains a constant color reproducibility under external light having any color components. It can be performed. Therefore, a high-quality and compact liquid crystal display device can be realized. By incorporating the FRC gradation control means in the data electrode drive unit,
The transfer frequency of the display data can be reduced, and the power consumption of the liquid crystal display device can be reduced.
Further, it can contribute to the reduction in thickness and weight of the reflective STN liquid crystal display device.

(Embodiment 4) Next, a reflective STN liquid crystal display device according to Embodiment 4 of the present invention will be described. FIG. 4 is a block diagram illustrating a configuration of a reflective STN liquid crystal display device 400 according to the present embodiment. Note that blocks and signal names having the same contents as those in the first and second embodiments are denoted by the same reference numerals, and detailed description is omitted. The liquid crystal display device 400 is characterized in that FRC gray scale control means for performing gray scale control of a display signal is integrated with a circuit section for driving data electrodes of a matrix liquid crystal panel.

The external light color component detecting means 101 is a detecting means for detecting a color component of external light. External light color component detecting means 10
1 is a red PWM signal.
Gradation control means 201, green PWM gradation control means 202,
It is given to the blue PWM gradation control means 203.

The liquid crystal signal control means 204 includes a display timing signal 106, a red display signal 107, a green display signal 10
8. A circuit which receives the blue display signal 109 and rearranges the display signals in a matrix for liquid crystal display in synchronization with the timing of the display timing signal 106. The display signals rearranged here are respectively referred to as red liquid crystal cell display signals 20.
5, a green liquid crystal cell display signal 206 and a blue liquid crystal cell display signal 207. These display signals are composed of a plurality of bits as in the case of the input of the liquid crystal signal control means 204. The display timing signal 106 is also converted into a liquid crystal display timing signal 115 by the liquid crystal signal control means 204.

The red PWM gradation control means 201 performs pulse width modulation in accordance with the bit value of the input red liquid crystal cell display signal 205 and changes the pulse width based on the red component ratio of the color component detection signal 105. This is control means for correcting and generating red liquid crystal cell display data 208. Similarly, green P
The WM gradation control unit 202 performs pulse width modulation in accordance with the bit value of the input green liquid crystal cell display signal 206, corrects the pulse width based on the green component ratio of the color component detection signal 105, This is control means for generating liquid crystal cell display data 209. Further, the blue PWM gradation control means 20
3 performs pulse width modulation corresponding to the bit value of the input blue liquid crystal cell display signal 207, and outputs the color component detection signal 10
Control means for correcting the pulse width based on the blue component ratio of No. 5 and generating blue liquid crystal cell display data 210.

The display data control means 401 includes a red liquid crystal cell display data 208, a green liquid crystal cell display data 209,
Control means for inputting the blue liquid crystal cell display data 210 and rearranging the data electrodes of the matrix liquid crystal panel 116 in the arrangement order. Display data voltage generating means 402
Is a unit for amplifying the PWM pulse of each color liquid crystal cell output from the display data control unit 401 to a drive voltage of each liquid crystal cell.

The matrix liquid crystal panel 116 is a reflection type liquid crystal panel using STN liquid crystal, and has a large number of scanning electrodes and a large number of data electrodes formed in a matrix. The scanning-side driving means 117 outputs the timing signal 11 for liquid crystal display.
5, a scan pulse is sequentially applied to each scan electrode. Each data electrode of the matrix liquid crystal panel 116 is driven by the data PWM pulse output from the display data voltage generating means 402.

Here, as shown by the dotted line in FIG.
WM gradation control means 201, green PWM gradation control means 20
2. The blue PWM gradation control unit 203, the display data control unit 401, and the display data voltage generation unit 402 are integrated as a hybrid IC, a monolithic IC, or an FPC board, and these circuit groups are referred to as a data electrode drive unit 403. . Here, the display data control unit 401 and the display data voltage generation unit 402 have the same function as the data side driving unit as in the first embodiment.

The operation of the thus configured reflective STN liquid crystal display device 400 will be described. Note that, after the display signals of the respective colors are input, the red PWM gradation control means 20
1. The signal processing up to the green PWM gradation control means 202 and the blue PWM gradation control means 203 is the same as that of the second embodiment, and the description of those parts will be omitted.

Red PWM gradation control means 201, green PWM
M gradation control means 202, blue PWM gradation control means 203
, Green liquid crystal cell display data 209, and blue liquid crystal cell display data 2
10 are input to the display data control means 401 and rearranged in the arrangement order of the respective data electrodes of the matrix liquid crystal panel 116. Then, the display data voltage generating means 402
Generates a data PWM pulse by voltage-amplifying the rearranged liquid crystal cell display data,
16 data electrodes.

On the other hand, the liquid crystal display timing signal 115 converted by the liquid crystal display control means 204 is also transferred to the scanning side driving means 117 and is converted into a scanning pulse. These scanning pulses are sequentially output to each scanning electrode of the matrix liquid crystal panel 116.

The reflection type STN liquid crystal display device 400 described above
When information is displayed by using, it is possible to always perform display with constant color reproducibility under external light having any color component. Therefore, it is possible to realize a reflective STN liquid crystal display device with high image quality by PWM gradation control. Further, by incorporating the PWM gradation control means in the data electrode drive unit 403, the size, thickness, and weight of the liquid crystal display device can be reduced.

[0072]

According to the first, second and third aspects of the present invention,
It is possible to always display information with constant color reproducibility under external light having any color component. For this reason, a high quality reflective STN liquid crystal display device can be realized.

According to the fourth and fifth aspects of the present invention, gradation control of a display signal and gradation correction by external light can be performed by frame rate control. Generally, the response of the STN liquid crystal is slower than other liquid crystals, and thus such a liquid crystal panel is used for on / off control. Even with such a control method, there is an advantage that gradation control and correction can be easily performed.

According to the sixth aspect of the present invention, gradation control of a display signal and gradation correction by external light can be performed by pulse width control. Generally, when the gradation control of the STN liquid crystal is performed by the frame rate control, flicker occurs depending on the arrangement of the blinking pixels. However, in the pulse width control, since the gradation control is performed in frame units, there is an effect that flicker does not occur.

According to the seventh aspect of the present invention, since the display signal gradation control means for each color is integrated with the data driving means, the transfer frequency of display data can be reduced. Further, the power consumption, thickness, and weight of the liquid crystal display device can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a reflective STN liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a reflective STN liquid crystal display device according to a second embodiment of the present invention.

FIG. 3 is a block diagram illustrating a configuration of a reflective STN liquid crystal display device according to a third embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a reflective STN liquid crystal display device according to a fourth embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional reflective STN liquid crystal display device.

[Explanation of symbols]

 101 external light color component detection means 102,301 red FRC gradation control means 103,302 green FRC gradation control means 104,303 blue FRC gradation control means 105 color component detection signal 106 display timing signal 107 red display signal 108 green display Signal 109 Blue display signal 110 Red liquid crystal display signal 111 Green liquid crystal display signal 112 Blue liquid crystal display signal 113, 204 Liquid crystal signal control means 114 Liquid crystal cell display data 115 Liquid crystal display timing signal 116 Matrix liquid crystal panel 117 Scanning driving means 118 Data side Driving means 201 Red PWM gradation control means 202 Green PWM gradation control means 203 Blue PWM gradation control means 205 Red liquid crystal cell display signal 206 Green liquid crystal cell display signal 207 Blue liquid crystal cell display signal 208 Red liquid crystal cell display data Data 209 Green liquid crystal cell display data 210 Blue liquid crystal cell display data 211 PWM data voltage generation means 307, 401 Display data control means 308, 402 Display data voltage generation means 309, 403 Data electrode drive unit

Claims (7)

[Claims] 1. A liquid crystal display device for displaying information on a liquid crystal panel by inputting a display signal of three colors composed of a plurality of bits as a gradation value of each pixel, and detecting an external light color component. A light color component detection unit, which converts a color display signal of each pixel input from the outside into a liquid crystal display signal based on the gradation value thereof, and converts the color display signal based on the component ratio of each color output from the outside light color component detection unit. A display signal gradation control means for correcting a gradation value of the liquid crystal display signal; a reflective matrix liquid crystal panel on which scanning electrodes and data electrodes are formed; and a liquid crystal output from the display signal gradation control means. Liquid crystal signal control means for rearranging a display signal into a pixel array of the reflective matrix liquid crystal panel; and applying liquid crystal cell display data output from the liquid crystal signal control means to data electrodes of the reflective matrix liquid crystal panel. A data-side drive unit; and a scan-side drive unit that converts a liquid crystal display timing signal output from the liquid crystal signal control unit into a scan pulse and sequentially outputs the scan pulse to a scan electrode of the reflective matrix liquid crystal panel. A liquid crystal display device characterized by the above-mentioned. 2. A liquid crystal display device for displaying information on a liquid crystal panel by inputting a display signal of three colors composed of a plurality of bits as a gradation value of each pixel, wherein external light applied to the liquid crystal panel is provided. External light color component detecting means for detecting a color component of the pixel; and converting a red display signal of each pixel input from the outside into a liquid crystal display signal based on the gradation value, and outputting from the external light color component detecting means. A red display signal gradation control means for correcting a gradation value of the liquid crystal display signal based on a red component ratio in the detected color component detection signal; A green display signal for converting a gradation value of the liquid crystal display signal based on a green component ratio in a color component detection signal output from the external light color component detection means, while converting the liquid crystal display signal into a liquid crystal display signal based on the value. Gradation control means; The blue display signal of each pixel input from the outside is converted into a liquid crystal display signal based on the gradation value, and based on the blue component ratio in the color component detection signal output from the external light color component detection means. A blue display signal gradation control unit for correcting a gradation value of the liquid crystal display signal; a red liquid crystal display signal output from the red display signal gradation control unit; and a red liquid crystal display signal output from the green display signal gradation control unit. A green liquid crystal display signal and a blue liquid crystal display signal output from the blue display signal gradation control means are respectively input and rearranged into a pixel array of the liquid crystal panel to create liquid crystal cell display data, and Liquid crystal signal control means for generating a liquid crystal display timing signal for instructing output timing to each pixel; scanning electrodes and data electrodes are formed in a grid pattern; A reflective matrix liquid crystal panel in which a liquid crystal responsive to an effective value voltage to be applied is held; and a liquid crystal cell display data output from the liquid crystal signal control means is subjected to voltage conversion and applied to data electrodes of the reflective matrix liquid crystal panel. A data-side drive unit; and a scan-side drive unit that converts a liquid crystal display timing signal output from the liquid crystal signal control unit into a scan pulse and sequentially outputs the scan pulse to a scan electrode of the reflective matrix liquid crystal panel. A liquid crystal display device characterized by the above-mentioned. 3. A liquid crystal display device for displaying information on a liquid crystal panel by inputting a display signal of three colors composed of a plurality of bits as a gradation value of each pixel, wherein a red color signal of each pixel input from the outside is provided. A display signal, a green display signal, and a blue display signal are rearranged into a pixel array of the liquid crystal panel to generate a liquid crystal cell display signal of each color, and a liquid crystal display timing for instructing an output timing to each pixel of the liquid crystal panel. A liquid crystal signal control unit that generates a signal; an external light color component detection unit that detects a color component of external light applied to the liquid crystal panel; and a red liquid crystal cell display signal output from the liquid crystal signal control unit. While converting to red liquid crystal cell display data based on the gradation value, based on the red component ratio in the color component detection signal output from the external light color component detection means,
A red display signal gradation control unit for correcting a gradation value of the red liquid crystal cell display data; and a green liquid crystal cell display data output from the liquid crystal signal control unit, based on the gradation value. And, based on the green component ratio in the color component detection signal output from the external light color component detection means,
A green display signal gradation control unit for correcting a gradation value of the green liquid crystal cell display data; and a blue liquid crystal cell display signal output from the liquid crystal signal control unit, based on the gradation value. And, based on the blue component ratio in the color component detection signal output from the external light color component detection means,
A blue display signal gradation control means for correcting the gradation value of the blue liquid crystal cell display data, a liquid crystal responsive to an effective value voltage applied between the two electrodes, wherein a scanning electrode and a data electrode are formed in a lattice shape. A liquid crystal cell display data output from the red display signal gradation control means, the green display signal gradation control means, and the blue display signal gradation control means. A data-side driving unit for providing a data electrode of the reflective matrix liquid crystal panel; and a liquid crystal display timing signal output from the liquid crystal signal control unit, which is converted into a scanning pulse. A liquid crystal display device comprising: a scanning-side driving unit for sequentially outputting data; 4. A method for controlling the gradation of each pixel, wherein the reflectance of the pixels of the liquid crystal panel is changed in units of frames and the rate of change is controlled in units of a plurality of frames. The display signal gradation control unit, the green display signal gradation control unit, and the blue display signal gradation control unit determine a gradation value of each pixel in the red, green, and blue display signals by using the frame rate control. 3. The liquid crystal display signal according to claim 2, wherein the gradation value of the liquid crystal display signal is corrected based on a color component ratio in the color component detection signal output from the external light color component detection means, while being converted into a liquid crystal display signal. Liquid crystal display. 5. A method for controlling the gradation of each pixel, wherein frame rate control is performed in which the reflectance of the pixels of the liquid crystal panel is changed on a frame basis and the rate of change is controlled on a frame basis. The display signal gradation control means, the green display signal gradation control means, and the blue display signal gradation control means convert the liquid crystal cell display signals of each color output from the liquid crystal signal control means into the frame based on the gradation values. Converting to liquid crystal cell display data using rate control, and correcting the gradation value of the liquid crystal cell display data based on the color component ratio in the color component detection signal output from the external light color component detection means. The liquid crystal display device according to claim 3, wherein: 6. A method for controlling gradation of each pixel, wherein the control is performed by PWM control in which a reflectance of a pixel of the liquid crystal panel is controlled by a pulse width of a data pulse applied for each frame. The gradation control means, the green display signal gradation control means, and the blue display signal gradation control means perform the PWM control based on the gradation value of the liquid crystal cell display signal of each color output from the liquid crystal signal control means. And converting the display data into liquid crystal cell display data, and correcting a gradation value of the liquid crystal cell display data based on a color component ratio in a color component detection signal output from the external light color component detection means. The liquid crystal display device according to claim 3. 7. A signal electrode driving unit in which said red display signal gradation control means, said green display signal gradation control means, said blue display signal gradation control means, and said data side driving means are integrated on the same substrate. 4. A liquid crystal display device according to claim 3, wherein said liquid crystal display device is incorporated in said reflective matrix liquid crystal panel.