JPH0359513A - Liquid crystal display system - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to liquid crystal display devices, and in particular to a liquid crystal driving method for obtaining good display quality without crosstalk in a simple matrix type liquid crystal display device. .

[Conventional technology]

Conventionally, for simple matrix type liquid crystal display devices, "Latest Technology of Liquid Crystals JP106-1" published by Kogyo Kenkyukai
It is driven by the voltage averaging driving method as described in 2009. According to this method, logically, a constant voltage is applied regardless of the display pattern on the liquid crystal display. However, depending on the type of display screen, the frequency component of the voltage applied to the liquid crystal differs, causing a problem in that brightness decreases. Problems with the prior art will be explained below using FIGS. 2 to 8. FIG. 2 is a block diagram showing the configuration of a conventional liquid crystal display device, where 1 is 4-bit wide display data, 2 is a data latch clock, and 3 is a horizontal clock. Display data synchronized with 2 is sent for 1h<1 horizontal period. That is, if the number of horizontal display dots is 640, display data 1 will be sent 160 times with 4 bits each. 4 is the start signal that instructs the display of the first line of the display, 5 is Xl
! The display data 1 is converted to the data latch clock 2 by the j-movement means.
The water molecules are taken in by the horizontal clock 3, and one line is simultaneously outputted to the liquid crystal panel by the horizontal clock 3. 6 is the X display voltage, 7
is the X non-display voltage, X1 to X640 are the X display signals, and according to the contents of each 640 dots of one line of display data taken in by the X operation means 5, when the data indicates display, 171 IT When the X display voltage 6 is set to 0, which indicates non-display, select the X non-display voltage 7, and select the X display signal X1~
Output to X640. In this embodiment, the X display voltage 6
Vxon, X non-display voltage 7 to V engineering. □ is applied. 8 is a Yllj moving means, 9 is a Y selection voltage, 10 is a Y non-selection voltage', Yl-Y2O2 is a line selection signal, and Y
The selection voltage 10 is V. , V for the Y non-selection voltage 11.

□ is applied. The Y drive means 8 takes in the leading signal 4 using the horizontal clock 3, and the line selection signal Y1 is a selection voltage of 7°. The other line selection signals are Va. □
shall be. Next, when horizontal clock 3 is input, line selection signal Y1 becomes vl. 8, and the line selection signal Y2 becomes v
Yo, and this process is repeated until the line selection signal Y
1 to Y 200 in sequence according to horizontal clock 3.
I will go with you. 20 is a liquid crystal panel, and line selection signals Yl-Y200. The dots to be displayed are formed by the intersections of the X display signals X1 to X640, and the display or non-display is performed based on the difference in the effective value of the voltage at each intersection.

FIG. 3 is a block diagram of an example of the X(llil manual 5), in which 21 is an X data shift means, 22 is shift data,
The X data shift means 21 shifts the display data l by one horizontal period (640 dots) at the falling edge of the data latch clock 2.
The data is taken in and output as shift data 22.

23 is a data latch means, and 24 is latch data.

The data latch means 23 takes in the shift data 22 at the falling edge of the horizontal clock 3 and outputs it as latch data 24. 25 is an
jQ", for 111", the X display voltage 6 is
Engineering. For Y and '0', the V function has an X non-display voltage of 7. □ is selected and output as X display signals X1 to X640.

FIG. 4 is a block diagram of an example of the Y driving means 8.
is a Y data latch means that captures the “1” state of the leading signal 4 at the falling edge of the horizontal clock 3 and outputs a shift output YOI.
is set as /J 1 rp, and then the shift outputs YO2, YO3, . . . and 111 are shifted in order according to the horizontal clock 3. 27 is a power selection means, and a shift output Y
○1 to YO200, for each output "1", the Y selection voltage 9 is v7°. Y non-select voltage 1 for 1rO''
V of 0,. 2. and select each line selection signal Y1~
Output as Y2O0. FIG. 5 is a diagram showing the display state of a part of the liquid crystal panel 20, in which the hatched areas are dots in the display state, and the X display signals x1 to X3. Line selection signal Y1
~Lll the dot at the intersection of Y3, E, 12...L3
It is shown as 1. FIG. 6 shows the X display signals X1-X3. during the display shown in FIG. FIG. 7, a timing diagram showing the driving waveforms of line selection signals Y1 to Y3, is a diagram showing voltage waveforms applied to dots Lll, L12, and L13 during the display shown in FIG. 5.

FIG. 8 is a diagram showing the effective voltage ratio applied to each dot of the liquid crystal and the brightness characteristics.

In FIG. 2, the X1lilu operating means 5 has the configuration shown in FIG. 3, and the X data shift means 21 takes in 640 dots of display data 1 for one line at the falling edge of the data latch clock 2, and thereafter horizontal clock 3
At the falling edge of , the captured data of 640 dots for one line is latched into the data latch means 23, and the X voltage selection means 25 is latched according to the values of "1" and '0' of each data.
V engineering. . Or V-engineering. 3 voltage as X display signal X1-X6
Output as 40.

At this time, the X data shift means 21 takes in the data of the next line, and as the output of the X opening means 5, the contents are outputted to the X display signals Xi to X640 one line at a time according to the falling edge of the horizontal clock 3. I will do it. Yllll manual 8 has the configuration shown in Fig. 4,
XIl[? Auxiliary means 5 converts the contents of the first line data to
At the timing of the falling edge of the horizontal clock 3 outputted to the display signals X1 to X640, the Y data shift means 26 latches the It 1 jl state of the leading signal 4, and the Y voltage select means 27 selects the line selection signal Y1. 1°.

shall be. After that, at the same time as the X-opening means 5 sequentially outputs the second and third lines according to the horizontal clock 3,
The Y opening operation means 8 uses the Y data shift means 26 to sequentially shift the "work" state from the shift output YOI to VO2, VO3, so that the voltage of V y o ++ is also changed from the line selection signals Y1 to Y2 . It will be shifted sequentially to Y3. One screen is displayed by repeatedly scanning the above steps.

Therefore, as shown in FIG. 5, the dots Lll, L21 . L3
Each dot L12 . . . 1 . L
22. All the dots L32... are displayed, and the dots L13... in the third column are connected to the X display signal X3. L2
3. When L33... are all hidden, the X opening movement means 5. X display signals X1 to X3 outputted from Yllll manual 8.
The line selection signals Yl to Y3 have timings according to the horizontal clock 3, as shown in FIG. Now ■a. 2
．． When Vxon=Vvotr+V*Vx, art"Vyorr-VaVToII=VYOIIVv with reference to Vxon=Vvotr+V*Vx, Lll is in the display state shown in FIG.

The voltage waveform shown in FIG. 7 is applied to the dot L12 and the dots 1 and 13 which are in the non-display state. Since the liquid crystal operates with the effective value of the applied voltage, the voltage applied to each dot is VLtt"zoo VT+V-+199V-"Vo1
1vC, L4=2oo vT+v, +199V-=
Vo-VLl, S= ,oo Vy+V, +199
An effective voltage ratio of V, =Vott is applied, and as shown in FIG. 8, the effective value is V. When Y is displayed, 100% brightness is displayed, and when VO and i are displayed, 10% brightness is displayed.

As explained above, when a dot is displayed or not displayed, when the line selection signal of the line where the dot exists is Vvott of the Y non-selection voltage IO, the voltage applied even if other dots are displayed or not Since the absolute values of are the same, the line selection signal is Vl of the Y selection voltage 9. . X when
Determined by the voltage value of the display signal.

[Problem to be solved by the invention]

The above-mentioned prior art does not take into account the frequency components of the voltage waveform applied to the dots.

For example, the effective voltage value given to Lll and L12 in FIG. 7 is V as described above. fi, but in a liquid crystal panel, as shown in Figure 9, as the frequency component of the voltage waveform applied to the dot increases, the voltage effective value-luminance characteristic shifts, so Even in terms of effective value ratio, there was a problem in that the luminance of Lll was lower than the luminance of L12.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display method that can eliminate brightness reduction due to display patterns and provide good display.

[Means to solve the problem]

In order to achieve the above object, in the present invention, X1l
The display voltage applied from the li drive means to the liquid crystal panel.

In order to make the non-display voltage pulse-like, l or O of the display data for one dot given to the X1lK driving means is
Interchange of pulse data or -L (N # b >N'
By providing a data dedacoding circuit for converting the data into Na5O), a voltage waveform with a constant frequency component is obtained regardless of the display pattern.

[Effect]

Set the display data for 1 dot on the X decommissioning means b
b Then, instead of 1, - In other words, period ■ is outputted from the X driving means by giving a pulse whose N period is "LO-" (however, N#b>a#) The X display signal is a display b as shown in FIG.
b When ON is - pulse (i.e. V period X display voltage pulse)
When the voltage is display OFF, it is ■pulse (non-display voltage VX
OFF pulse) voltage is now applied. As a result, line selection (Y selection voltage ■.1
When the line is not selected (Y non-select voltage, FF output), the pulse-like X display signal voltage waveform as described above is applied, so the display data.

The frequency component of the effective value of the voltage applied to the liquid crystal does not change significantly depending on the display pattern.

〔Example〕

An embodiment of the present invention will be described below in Fig. 1 and Figs. 10 to 1.
This will be explained using Figure 5.

FIG. 10 is a block diagram showing an embodiment of the present invention,
1 is a display data bus for displaying one line; 2 is a display data bus for displaying one line;
Line memories 9a and 29b are line memories A and B that store display data for one line.

32 is a pulse clock 28. This is a data select signal generation circuit that generates a data select signal based on horizontal clock 3. This data select signal is a signal that repeats "high" and "low" according to the horizontal clock that indicates one line period, and thereby 30 data select signals are generated. Switch the circuit. 1, 2, 3, 4°5.8, 20 are the same as in FIG.

In FIG. 10, display data for one line is alternately stored in line memory A/29a or line memory B.
29b, and alternately read each line from the line memory opposite to the one from which it is taken. The data selector 30 alternately switches the data from the line memory mentioned above, and inputs the switched line memory data 31 to the data decoding circuit 33.

This data decoding circuit 33 stores line memory data 3.
Two types of display # O in one line of display information of 1
The N jj2 display "OFF" data is converted into display pulse data 34 of two types of display ON pulse and display OFF pulse, respectively, and output to the X driving means 5. Each of these display ON pulses and display OFF pulses is data for displaying an L dot, and as shown in FIG. 11,
This is pulse data that is 1 during the 1-dot display period, that is, "High"', and the waveform of the display OFF pulse is the opposite of the pulse waveform of the 1-display ON pulse, and T during the 1-dot data period is 0, that is, "High". , ## Lo, II.

The X driving means 5 takes in the display pulse data 34 for l life display using the data latch clock, and at the subsequent fall of the pulse clock 28, outputs the X display signal indicated by the display pulse data 34 for one line from the Xi. Output to X8. Further, while the X driving means 5 is outputting the display pulse data 34 for the above-mentioned l line, the data latch clock 2 outputs the display pulse data 34 for one line of the next line.
Incorporate.

At the subsequent fall of the pulse clock, the display signal indicated by the display pulse data 34 is outputted from Xl to X8.

This X [display information applied from auxiliary means 5, X1 to X8
is applied to the liquid crystal on the 1 line of the output Yl-Y8 of the Y-driving circuit 8, which is at "High" at that time, and an amount of light proportional to the displayed information is transmitted.

The Y drive means 8 takes in the head signal 4 using the horizontal clock 3, sets Yl to 14 H1ghlj, and then shifts "High" to Y2, . . . , Y8 using the horizontal clock 3.

Now, move this liquid crystal panel 20 horizontally from X1 to X8. Vertical Yl-
The size is Y8, 8x8 dots, and the waveforms applied to the liquid crystal panel are shown in Figures 12, 13, and 14.

In Figure 12, an 8x8 dot size liquid crystal panel 2
0, the above-mentioned YISH operation means 8 when the entire OFF display is displayed.
The output waveform (Y2) of the output Y2 and the output waveform (X2)' of the output X2 of the X driving means 5 are shown, respectively. From these, 1 dot (X coordinate = 2.Y
The signal waveform applied to the liquid crystal at coordinates = 2) is (X2.Y2)
' as shown.

Signal waveform by conventional liquid crystal panel opening method (X2°Y2)
In comparison, even when displaying OFF, when Y2 is selected, the display becomes ON level by the width of T dorato, and even when other than Y2 is selected,
A display OFF level pulse is applied to every l dot.

Next, in FIG. 13, the entire surface of the liquid crystal panel 20 is
The output waveform (Y
2) and the output waveform (X2
)' are respectively shown, and from these, the signal waveform applied to the liquid crystal of the L dot (X coordinate = 2. Y coordinate = 2) on the liquid crystal panel 20 is as shown in (X2.Y2)', which is different from that of the conventional liquid crystal panel. Compared to the signal waveform (X2.Y2) due to the driving method, the time at the display ON level during ON display, that is, when Y2 is selected, is the U dot width, and even when Y2 is not selected,
A pulse is applied to each dot in the display OFF level region.

Next, in FIG. 14, in the liquid crystal panel 20, each line from the top shows OFF display, ON display, OFF display,
When displayed alternately, the output waveform (Y2) of the output Y2 of the Y drive means 8 and the output waveform (X2)' of the output X2 of the X drive means 5 are shown. From these, the signal waveform applied to the liquid crystal of one dot (X coordinate = 2, Y coordinate = 2) on the liquid crystal panel 20 is as shown in (X2.Y2)', and the signal waveform (X2
．． Compared to Y2), the time at the display ON level during ON display, that is, when Y2 is selected, is the width of a royal dot.

As shown in FIG. 12.13, the signal waveform applied to the liquid crystal in this embodiment is (X2.Y2) compared to the conventional example (X2.Y2).
As shown in (X2.Y2)' in Figure 14, the number of signal change points increases when Y2 is not selected, and the frequency component (component indicating the number of signal changes within one fixed time) increases. 'The difference in frequency components is smaller than that of the conventional one.

FIG. 15 is a block diagram showing an embodiment of the present invention, l is display data, 35 is a data decoder that converts the display data, and the display data converted by the data decoder 35 is 36 The signal is output to an X driving means capable of displaying a gradation liquid crystal display. As the X driving means 36 capable of displaying this gradation liquid crystal display, there is currently the rT9831 (16-tone LCD column dryer) manufactured by Toshiba. 2.3, 4, 8 in the diagram
．． 20 is the same as in FIG.

In FIG. 15, when the display data of one dot is display ON data or display OFF data, the data decoder 35 inputs each of them and outputs another gradation display data 37. The signal is converted into H and DOFF and output to the X opening movement means 36 capable of displaying a gradation liquid crystal display. This X driving means 36 shifts the gradation display data 37 using the data latch clock 2, and outputs X1 to x8 as liquid crystal active outputs corresponding to the gradation display data 37. Now, the gradation display data 37 for 1 dot is DoN or not. When F, X driving means 3
6 is shown in FIG. 16, and outputs a high driving output of pulses of -0N level and -ioFF level. At that time, the liquid crystal active outputs X1 to x8 applied from this X opening means 36 are “High”.
” is applied to the liquid crystal on one line of the outputs Y1 to Y8 of the active circuit 8, and a light amount proportional to the liquid crystal active output is transmitted. 3, set Yl to "High", then set "High to Y2" by horizontal clock 3...
・Shift to Y8.

Now, move this liquid crystal panel 20 horizontally from X1 to X8. Vertical Yl~
The size of Y8 is 8×8 dots, and the display on the liquid crystal panel and the waveform applied thereto are shown in FIG. 12.1314.

In Figure 12, an 8x8 dot size liquid crystal panel 2
0, the output waveform (Y2) of the output Y2 of the Y drive means 8 and the output waveform (X2)' of the output x2 of the X drive means 5 at the time of full-screen OFF display are shown, respectively. From these, the signal waveform applied to the liquid crystal of one dot (X coordinate = 2. Y coordinate = 2) on the liquid crystal panel 20 is (X2.Y2)'
Compared to the signal waveform (X2°Y2) obtained by the conventional liquid crystal panel activation method, even when displaying OFF, when Y2 is selected, the display becomes ON level by the width of +/- dorato, and Y
Even in cases other than 2 selections, a display OFF level pulse is applied to each dot.

Next, in FIG. 13, the entire surface of the liquid crystal panel 20 is
The output waveform (Y
2) and the output waveform (X
2)' are respectively shown, and from these, the signal waveform applied to the liquid crystal of one dot (X coordinate = 2, Y coordinate = 2) on the liquid crystal panel 20 is as shown in (X2.Y2)', which is the same as that of the conventional liquid crystal. Signal waveform by panel driving method (X2', Y2)
Compared to the above, the time at the display ON level during ON display, that is, when Y2 is selected, is the width of a standing dot, and even when Y2 is not selected, a pulse is applied to each dot, although it is in the display OFF level region.

Next, in FIG. 14, when the liquid crystal panel 20- displays OFF display, ON display, OFF display, ON display alternately from the top line by line, the above-mentioned Y[
The output waveform (Y2) of the output Y2 of the moving means 8 and the output waveform (X2)' of the output X2 of the moving means 5 described above are shown. From these, the signal waveform applied to the liquid crystal of one dot (X coordinate = 2. Y coordinate = 2) on the liquid crystal panel 20 is (X2.Y2)'
The signal waveform (
X2. Compared to Y2), the time at the display ON level during ON display, that is, when Y2 is selected, is the width of T dots.

As shown in FIG. 12.13, the signal waveform applied to the liquid crystal in this embodiment is (X2.Y2) compared to the conventional example (X2.Y2).
As shown in (X2.Y2)' in Fig. 14, the number of signal change points during non-selection other than when Y2 is selected increases, and the frequency component (component indicating a signal change within one fixed time) becomes higher. The difference between the frequency components is smaller than that of the conventional method.

〔Example〕

According to the present invention, as described above, an opening pulse is given to the liquid crystal as a liquid crystal drive signal even during a non-selection period (when other lines are selected), regardless of whether the display is ON or the display is OFF. No matter what display pattern is displayed on the LCD panel,
Compared to the conventional technology, the frequency characteristic range of the liquid crystal opening signal can be made smaller. In addition, by reducing variations in the frequency characteristics of this LCD display drive signal, the shift in effective value vs. brightness characteristics is small, and by matching the characteristics of the liquid crystal panel itself to its frequency characteristics, no matter what display pattern data is used, the brightness decreases. It can be displayed neatly without any problems.

[Brief explanation of drawings]

1 is a diagram showing the liquid crystal driving voltage waveform of the present invention, FIG. 2 is a diagram showing a conventional liquid crystal display device, FIG. 3 is a block diagram of the XtilK operating means, FIG. 4 is a block diagram of the Y opening operating means, and FIG. 5
The figure shows a liquid crystal matrix, Figures 6-7 show applied voltage waveforms, Figures 8 and 9 show luminance-effective voltage ratio graphs, and Figures 10 and 15 show an embodiment of the present invention. 11 is a diagram showing the display pulse data waveform, Figures 12, 13 and 14 are diagrams showing the display pattern and its liquid crystal applied voltage waveform, and Figure 16 is the gradation display X-circle. FIG. 3 is a diagram showing an output waveform of a moving means. DESCRIPTION OF SYMBOLS 1... Display data, 33... Data decoding circuit, 4... Y opening means, 5... X opening means, 36... Gradation display X driving means, 20... Liquid crystal panel. Leather 1 Figure (α) When oFF is applied, the voltage applied is yf, and the figure is (lV>4) Figure 5. $ Kanka Makkatsu 10 Kandai 2 Zuka 3 Figure 1 + Figure

Claims (5)

[Claims] (1) An X driving means that captures one line of display information and outputs it to the liquid crystal panel, and a Y driving means that selects the one dot data outputted by the X driving means for each line; In a matrix display device that displays data on one dot of the liquid crystal panel selected by the Y drive means, the X display signal output from the X drive means has a voltage waveform with one or more voltage change points during one dot display period. A liquid crystal display system characterized by: (2) The X display signal outputted by the X driving means has two types of voltage waveforms in which the voltage changes at point b/N or point a/N during one dot display period. The liquid crystal display method described (however, N>b>a≠0). (3) The liquid crystal display method according to claim 1, wherein the voltage waveforms b/N and a/N of the two types of X display signals outputted by the X driving means have a relationship of b=N−a (provided that , N>b
>a≠0). (4) A data decoding circuit for converting one-dot display data into pulsed display data having one or more change points is provided in front of the X driving means, and the pulsed display data output from the data decoding circuit is converted into pulsed display data. 2. A liquid crystal display circuit in a display system according to claim 1, wherein the liquid crystal display circuit is inputted to an X driving means. (5) The liquid crystal display circuit in the display system according to claim 1, wherein the X driving means is provided with a gradation display function, and a data decoder is provided in front of the X driving means.