JPH0359596A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To eliminate the deterioration of luminance caused by a display pattern and to obtain a satisfactory display by providing a horizontal retrace line period, and driving an X electrode independently from dispaly data in the horizontal retrace line period. CONSTITUTION:The device is provided with an X voltage selector 12 for selecting a driving voltage given to an X driving means, and a Y voltage selector 16 for selecting a driving voltage given to a Y driving means, and also, provided with a horizontal retrace line period, and a voltage applied to a liquid crystal panel 20 is provided newly in this horizontal retrace line period. Accordingly, a frequency component of a voltage waveform applied to each dot of the liquid crystal panel 20 can be set to the same without depending on the display pattern. In such a way, the dependency of the display luminance and the display pattern is eliminated, and a uniform display being free from a lunimance omission can be obtained.

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 opening method for obtaining good display quality without reduction in brightness due to display patterns in a simple matrix type liquid crystal display device. and its apparatus.

[Conventional technology]

Conventionally, for simple matrix type liquid crystal display devices, "Latest Technology of Liquid Crystals" published by Kogyo Kenkyukai, P106-1
It is driven by the voltage averaging driving method as described in 2009. According to this method, 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 waveform 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 one horizontal period. That is, if the number of horizontal display dots is 640, the display data 1 will be loaded 160 times with 4 bits each. 4 is a start signal that instructs the display of the first line of the display, 5 is an X drive means, which takes in display data 1 for 1 horizontal 5 minutes with data latch clock 2, and then reads 1 line of display data at the same time with horizontal clock 3 - the liquid crystal panel. Output to. 6 is X display voltage, 7 is X non-display voltage,
1 to X640 are X display signals, and according to the contents of each 640 dots of display data 1 for 1 line taken in by the X driving means 5, when the data is 111' indicating display,
When the display voltage 6 is 1φ' indicating non-display, the X non-display voltage 7 is selected and outputted to the X display signals X1 to X640.

In this embodiment, the X display voltage 6 is a voltage of vxon.

A voltage of Vxoff is applied to the X non-display voltage 7.

8 is a Y drive means, 9 is a Y selection voltage, 10 is a Y non-selection voltage, Y1 to Y2O0 are line selection signals, the Y selection voltage 10 is the voltage of Vyon, and the Y non-selection voltage 11 is the voltage of Vyo.
A voltage of ff is applied. The YIlj moving means 8 takes in the leading signal 4 using the horizontal clock 3, and outputs the line selection signal Y.
1 is the selection voltage Vyon, and the other line selection signals are Vyoff. Next, when the horizontal clock 3 is input, the line selection signal Y1 becomes Vyoff, the line selection signal Y2 becomes Vyon, and this is repeated.
Line selection signal Yl.

~Y2O0 sequentially according to horizontal clock 3, and then Vyo
Let's go with l. Reference numeral 20 denotes a liquid crystal panel, which forms dots that are displayed at the intersections of the line selection signals Y1 to Y2O0 and the X display signals Xi to X640, and displays or hides the display based on the effective value difference between the voltages at each intersection.

FIG. 3 is a block diagram of an example of the configuration of the X driving means 5,
21 is an X data shift means, 22 is shift data,
The data shift means 21 takes in one horizontal portion (6401-') of display data at the falling edge of the data latch clock 2 and outputs it 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 X voltage selection means, and 111'''φ indicated by each data of 640 dots of latch data 24
', for ll', VXOn of X display voltage 6
For +%φ', Vxoff of the X non-display voltage 7 is selected and outputted as the X display signals X1 to X640.

FIG. 4 is a block diagram of a configuration example of the Yllll manual 8, in which 26 is a Y data shift means which takes in the 11' state of the leading signal 4 at the falling edge of the horizontal clock 3, sets the shift output Y01 to 1', and then , the shift outputs YO2, YO3, . . . and 1' are shifted in order according to the horizontal clock 3. 27 is a power selection means, which outputs shift outputs Y01 to Y.
For each output 11' with O200, the Y selection voltage 9 V
For YOny ′″φ′, Y non-selection voltage 10 V
yoff, and each line selection signal Y1~Y2O
Output as 0.

FIG. 5 is a diagram showing a display pattern 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. The dots at the intersections of the line selection signals Y1 to Y3 are indicated by Lll, L, □...L, 1. FIG. 6 shows the X display signals X1 to X3.
FIG. 7 is a timing diagram showing the drive waveform of the line selection signal Yl-Y3. When the display shown in FIG.
, L12. It is a figure which shows the voltage waveform applied to L work 3. 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 X drive means 5 has the configuration shown in FIG.
After 40 dots are captured, at the subsequent falling edge of the horizontal clock 3, the data of 640 dots for 1 line captured is latched into the data latch means 23, and each data! 11
According to the value of 1φ', the X voltage selection means 25 selects v xo
The voltage of n or Vgoff is output as X display signals X1 to X640. At this time, the X data shift means 21 takes in the data of the next line, and as the output of the X drive means 5, the X display signals Xi to X64. The contents will be output to O.

The Y driving means 8 has a configuration shown in FIG. 4.

The Y data shift means 26 latches the "117" state of the head signal 4 at the timing of the falling edge of the horizontal clock 3 when the X opening actuator 5 outputs the contents of the head line data to the X display signals X1 to X640.

The line selection signal Y1 is set to V by the Ym pressure selection means 27.
Let it be VQn. After this, XI! At the same time as the ili movement means 5 outputs the second line and third line RO sequentially according to the horizontal clock 3, the Y opening movement means 8 causes the Y data shift means 26 to shift the 1" state from the output YOI to YO2,
Since the voltage of V'10n is sequentially shifted from YO3, the voltage of V'10n is also sequentially shifted from line selection signal Y1 to Y2 to Y3. By repeatedly scanning the above, one screen is displayed.

Therefore, as shown in FIG. 5, the first column of dots Lll, L21, L31, .
. . , the dots in the second column are connected to the X display signal X2, L12. L22
．． All dots of L32... are displayed, X display signal X3
The dot L13. in the third column is connected to the dot L13. L23. L3
3... are all hidden, XlN11 operating means 5.
Yl [X display signals X1 to X3 . The line selection signals Y1 to Y3 have timings according to the horizontal clock 3, as shown in FIG. Now, with Vyoff as the reference, V xon = V yof f + V (LVxo
ff=Vyoff VCL Vyon=Vvoff v,.

Then, the display state shown in FIG. 5 is obtained. Lll, L
The voltage waveform shown in FIG. 7 is applied to the dot No. 12 and the dot L13 which is in the non-display state. Since the liquid crystal operates according to the effective value of the applied voltage, the effective value is applied to each dot at the effective voltage ratio shown by, and as shown in Figure 8, the effective value ratio is VOn.
When it is set to 100% m degree display, and when it is set to voff it becomes a non-display state with 10% brightness.

As explained above, when a dot is displayed or not displayed, when the line selection signal of the line where the dot exists is the Y non-selection voltage of 10 Vyoff, the voltage that is applied even if other dots are displayed or not is displayed. Since the absolute values of are the same, when the line selection signal is Vyon of Y selection voltage 9,
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 voltage effective value ratio given to Lll and L12 in FIG. 7 is the same as VOn as described above, but in a liquid crystal panel, as shown in FIG. As the component becomes higher, the voltage effective value ratio-luminance characteristic shifts, so there is a problem that the luminance of Lll is lower than the luminance of L12 even with the same voltage effective value ratio of 1on.

An object of the present invention is to provide a liquid crystal display device 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, an X voltage selector means for selecting the driving voltage to be applied to the X driving means, a Y voltage selector means for selecting the opening voltage to be applied to the Y rotation means, and a horizontal retrace period is provided. By providing a new voltage to be applied to the liquid crystal panel during the horizontal retrace period, the difference in frequency components of the applied voltage waveform due to display patterns is reduced.

[Effect]

The X voltage selector means sets the X display voltage and the X non-display voltage to the same voltage value vB during the horizontal retrace period, and during the display period,
The X display voltage is xOn, and the X non-display voltage is Vxoff. Yf! Similarly, in the voltage selector means, during the horizontal retrace period, both the Y selection voltage and the Y non-selection voltage are set to V, which is the same voltage as the X side, and during the display period, the Y selection voltage is set to Vyont, and the Y non-selection voltage is set to Vvoff. In order to operate, the voltage applied to the dots during the horizontal retrace period is 1φ', and the voltage waveform always returns to 1φ' every horizontal line, so its frequency component hardly changes depending on the display pattern.

Further, since the applied voltage during the horizontal retrace period is 1φ', the effective value of the voltage applied to the dots does not change, and therefore the contrast does not change.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1 and FIGS. 1O to 14. FIG. 1 is a block diagram of an embodiment of the present invention, in which 1 to 0 and 20 are the same as in FIG. X voltage selector, 13 is X on voltage, 14 is X off voltage, 15 is X retrace voltage, X voltage selector 2 displays X retrace voltage 15 when horizontal retrace signal 11 is 11# Output as voltage 6, X non-display voltage 7, when 'φ',
The on voltage 13 is output to the X display voltage 6 and the X off voltage 14 is output to the X non-display voltage 7. 16 is a Y voltage selector, 17 is a Y on voltage, 18 is a Y on voltage, and 19 is a Y retrace voltage.
', the Y retrace voltage 19 is set to the Y selection voltage 9. It outputs to the Y non-selection voltage 10, and at the time of φl, outputs the Y-on voltage F to the Y-selection voltage 9 and the X-off voltage 18 to the Y non-selection voltage.

Note that in this embodiment, the X-on voltage is 13. X off voltage 14,
Off voltage 17. To the X off voltage 18, each VXOn* V
A voltage of xoff+Vyont vvoff is applied, and the X retrace voltage is 15. It is assumed that a voltage of VB is applied to both the Y retrace voltage and the upper 9.

FIG. 10 shows input display data 1. Data latch clock 2. Horizontal clock 3. Horizontal retrace signal 11. FIG. 11, a timing diagram showing the relationship between the leading line signals 4, is a diagram showing a part of the display pattern on the liquid crystal panel 20, with diagonal lines indicating display states.

Dots at the intersections of the X display signals X1 to X3 and the line selection signals Y to Y3 are Lll, L12...L32. It is indicated by L33.

FIG. 12 shows the line selection signal Y output from the y* moving means 8.
FIG. 13, which is a diagram showing the output waveforms of 1 to Y3, is a diagram showing the display pattern of FIG. X outputted by the moving means 5
14 is a diagram showing the output waveforms of the display signals X1 to X3. FIG. 14 shows dots Lll, L12 . It is a figure showing the voltage waveform applied to L13.

In FIG. 1, display data 1 is synchronized with data latch clock 2, and 160 data of 4 bits each are sent during one cycle of horizontal clock 3 at 12 degrees, as shown in FIG.
Due to the falling edge of this data latch clock 2,
! The 640 dots (
The data of 4X 160=640) is taken into the latch means in the XIN driving means S all at once at the falling edge of the horizontal clock 3, and according to the data value, when '11, the X display voltage is 6, and the When the X non-display voltage 7 is the X display signal X1
~ Output to X640. At this time, the driving means 5 also takes in the data of the next line, and at the falling edge of the next horizontal clock 3, the X display voltage 6 or X
Non-display voltage 7 is output to X display signals Xi to X640.

Therefore, the X driving means 5 synchronizes with the falling edge of the horizontal clock 3 and sequentially follows the data line by line.
Display voltage 6 or X non-display voltage 7 as X display signal X1 to X
640. Further, the X opening movement means 5 is 1
At the falling edge of the horizontal clock 3 after taking in the line data, the voltage according to that data is applied to the liquid crystal panel 2.
As shown in FIG. 10, in order to give the first line data to 0, the Y clearing means 8 outputs ``1'' of the leading signal 4 at the falling edge of the next horizontal clock 3 to which the data of the first line is input. launch the state, set the line selection signal Yl to Y selection voltage 9,
The other line selection signals Y2 to Y-200 are designated as a Y non-selection signal 10. After that, the value of the Y selection voltage 9 is sequentially changed to the line selection signals Y2 and Y3 at the falling edge of the line clock 3.
...It will shift to Y2O0.

X-opening means 5 explained above. By the operation of the Y movable means 8, the X motive means outputs a voltage according to the data of the line of the liquid crystal panel 20 whose output voltage is the Y selection voltage 9 among the line selection signals Y1 to Y2O0, and this One screen is displayed by repeating the operation from the jth line to the 200th line.

Next, the voltage actually applied to each driver 1- of the liquid crystal panel 20 will be explained.

Now, as shown in FIG. 11, the liquid crystal panel 20 has dots L11, L21, . L3
1..., the display and non-display are repeated as dots L12, L22, . . . are connected to the X display signal X2. L32・
. . . only displays the dot L13 . connected to X display 4Z % X 3. L23, L33, . . . have a display pattern in which only non-display is performed.

Now, with Vyoff as the reference, V xon = V yof f 10V CLVxof
If f=Vyoff V (L Vyol = Vyoff Vy V B = Vyoff-Vy/2), when the liquid crystal panel 20 has the display pattern shown in FIG. X1 to X640. Line selection signal Y1...
The output of Y2O0 is as follows.

Line selection signals Y1 to Y3 output from YilK driving means 8
As shown in FIG. 12, the horizontal retrace signal 11 is 11'
When is Y? 1 by voltage selector 16, Y selection voltage 9.
Both Y non-selection voltages 10 are VB of the Ys line voltage 19, so they are VB, and during the display period when the horizontal retrace signal 11 is 1φ", the Y selection voltage 9 is set by the Y voltage selector 16 to be VB of the Ys line voltage 19. The line selection signal Y1
is VYOn for the second line + Vy for other lines
off, the line selection signal Y2 becomes Vyoff for the second line, VYOn+4, and Vyoff for the other lines, and the line selection signal Y3 becomes vYoff for the third line, Vyon+other lines. In addition, as shown in FIG. 13, when the horizontal retrace signal 11 is 1 minute, the
2, the X display voltage 6. Since the X non-display voltage 7 is the voltage vB of the X retrace voltage 15, the X display signals X1 to X3 are both VB, and in the display period when the horizontal retrace signal 11 is 1φ1, the X display voltage 6 is Voltage 13 ■xon, X
Since the non-display voltage 7 becomes Vxoff of the X off voltage 14, 1'1φ' of the display data taken in by the
In order to set the X display signal to VXOn+Vxoff, the X display signal X1 alternately repeats Vxon+Vxoff line by line, and the X display signal
XOn* The X display signal X3 takes the voltage value of all lines V)(off).

At this time, each dot Lll, L12, L on the liquid crystal panel 20
The voltage waveform applied to i2 is as shown in Fig. 14,
The relative ratio of each voltage effective value is.

V L 11 = 200 VYVyV + 19
9 V, =Vo1VLtz: vl, +
v, +199V (L = Von00, which is the same value as the conventional example.

However, as is clear from FIG. 14, a horizontal retrace period is provided, and at that time, the X display signals X1 to X640 and the line selection signals Y1 to Y2O0 are set to VB, and the voltage is applied to each dot on the liquid crystal panel 20. 1φ', the frequency components of the voltage waveforms applied to each dot are the same, making it possible to keep the brightness characteristics of the liquid crystal constant regardless of the display pattern.In addition, in this embodiment, the horizontal blanking line Although selection of the active voltage by the signal 11 is provided outside the XiH driving means s and the Yil driving means 8, it can also be realized by providing this selection function inside each active means. Next, examples of each active means in this case will be described.

FIG. 15 is a block diagram of an embodiment of the X11K operating means 5 when the voltage selection by the horizontal retrace signal 11 is provided inside the active means, and 29 is a block diagram when the horizontal retrace signal 11 is 1 phase. When the horizontal retrace signal 11 is 1φ", according to each data of the 640-dot latch data 24,
It is an X voltage output means that outputs an X display voltage 6 when the data is 11, and an X non-display voltage 7 when the data is 1φ",
Other details are the same as in Figure 3.

FIG. 16 is a block diagram of an embodiment of the Y driving means 8 in the case where the voltage selection based on the horizontal retrace signal 1 is provided inside the active means. Y when .
When the horizontal retrace signal 1t+ is 1φ', the retrace voltage 19 becomes the Y selection voltage 9.'φ1 for the shifted output YOI-Y0200. For each output, there is a Y voltage output means for outputting a Y non-selection voltage 10 as line selection signals Y1 to Y2O0, respectively, and the other parts are the same as in FIG.

As explained above, the X driving means 5 in FIG. 15 and the Y driving means 5 in FIG.
When the driving means 8 is used, the configuration shown in FIG.
The same effect as the liquid crystal display device shown in the figure can be obtained.

In FIG. 17, the X display voltage 6 is Vxor++, the X non-display voltage 7 is VxofL, the X return voltage voltage 5 is VB,
Vyol for Y selection voltage 9, V for Y non-selection voltage 10
Suppose that a voltage of yoff is applied.

〔Effect of the invention〕

According to the present invention, it is possible to make the frequency components of the voltage waveform applied to each dot of the liquid crystal panel the same regardless of the display pattern, thereby eliminating the dependence between display brightness and display pattern and reducing brightness drop. No uniform display can be obtained.

[Brief explanation of drawings]

Fig. 2 is a block diagram of an embodiment of a liquid crystal display device of the present invention, Fig. 2 is a block diagram of an embodiment of a conventional liquid crystal display device, and Fig. 3 is a block diagram of an embodiment of the XfilU driving means.
FIG. 4 is a block diagram of an embodiment of the Y5 [u auxiliary means;
The figure shows an example of a display pattern on a liquid crystal panel, Figure 6 is a timing diagram of the driving waveforms of the line selection signal and the
The figure is a timing diagram of the voltage waveform applied to the dots on the liquid crystal panel, Figure 8 is a diagram showing the effective value voltage ratio-luminance characteristics of the liquid crystal, and Figure 9 is the frequency component of the voltage waveform applied to the dots on the liquid crystal panel. Figure 10 is a diagram showing the input timing to the liquid crystal display device, Figure 1 above is a diagram showing an example of one display pattern on the liquid crystal panel, Figure 12 is a diagram showing changes in the effective value voltage ratio-luminance characteristics due to differences in Figure 13 is a timing diagram of the output waveform of the line selection signal, Figure 13 is a timing diagram of the output waveform of the X display signal, Figure 14 is a timing diagram of the voltage waveform applied to the dots on the liquid crystal panel, and Figure 15 is one of the X active means. Block Diagram of Embodiment FIG. 16 is a block diagram of a liquid crystal display device according to an embodiment of the invention, which is an embodiment of the Y active means. 1...Display data, 2...Data latch clock,
3...Horizontal clock, 4...Start signal, 5...X
Active means, 6...X display voltage, 7...X non-display voltage, 8...Y active means, 9...Y selection voltage, 10...
・Y non-selection voltage, 11...Horizontal retrace line No. 13, 12...
x voltage selector, 13...X on voltage, 14...X
Off voltage, 15...X return voltage, 16...Y voltage selector, 17...Y on voltage, 18...Y off voltage, 19...Y return voltage, 20...LCD panel ,Xl-
X640...X display signal, Y1-Y2O0...line selection signal, 21...X data shift means, 22...
・Shift data, 23...Data latch means, 24.
...Latch data, 25...X voltage selection means, 2
6...Y data shift means, YO1 to YO200...
・Shift output, 27...Y voltage selection means, 29.
...X voltage output means, 31...Y voltage output means. Collection 5 Illustrated! Otsu diagram b hull, V=

Claims (1)

[Claims] 1. A liquid crystal panel comprising n X electrodes, m Y electrodes, display dots formed between the X electrodes and the Y electrodes, and display data inputted to the display data. In a display device comprising an X driving means for driving the X electrode and a Y driving means for driving the Y electrode with a corresponding voltage, a horizontal retrace period is provided, and the horizontal retrace period is independent of the display data. A liquid crystal display device characterized in that the X electrode is driven. 2. The liquid crystal display device according to claim 1, further comprising voltage switching means for switching the liquid crystal drive voltages input to the X driving means and the Y driving means during a retrace period and a display period. 3. The liquid crystal display device according to claim 2, wherein the voltage switching means is provided separately for the X driving means and for the Y driving means. 4. X data shift means for taking in one horizontal portion of display data, latch means for taking in one horizontal portion of display data taken in by the X data shift means using a horizontal clock, and each according to the contents of the display data taken in by the latch means. In a liquid crystal driving device comprising an X voltage selection means that outputs a corresponding voltage, a retrace signal that separates a display period and a retrace period is input, and the X voltage selection means outputs display data of the latch means during the retrace period. A liquid crystal driving method characterized by outputting a voltage unrelated to. 5. A liquid crystal driving device comprising a Y data shift means that captures a line head signal using a horizontal clock and then shifts the horizontal clock, and a Y voltage select means that outputs a voltage according to the output data of the Y data shift means, A retrace signal that separates a display period and a retrace period is input, and the Y voltage selection means outputs a voltage unrelated to the output content of the Y data shift means during the retrace period. LCD driving method.