JPS60220394A - Driving of liquid crystal display unit - 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] [Technical Field of the Invention] This invention relates to electronic wristwatches, small electronic calculators, liquid crystal TVs, etc.
The present invention relates to a matrix type liquid crystal display device used for image display such as television and a method for driving the same.

[Prior art]

In recent years, this type of liquid crystal display device has been widely used in electronic wristwatches, particularly liquid crystal TVs, and is configured as follows.

That is, a large number of strip-shaped electrodes, in other words, scanning electrodes and signal electrodes, are arranged perpendicularly to each other, and a liquid crystal material is held in the portion sandwiched between them, and the intersection of these electrodes is Images are displayed by combining parts (display dots). However, in this type of device, when driving display dots in a time-division manner, it is difficult to avoid blurring of the image due to crosstalk and a decrease in contrast due to slow response when trying to increase the number of time divisions, that is, the number of display dots. The problem was that I couldn't do it.

Therefore, in order to solve the above-mentioned problems, attempts have been made in the past to control the voltage applied to the display electrodes using active elements to substantially statically drive the liquid crystal. This type of address system is called an active matrix addressing system, and is configured as shown in FIG. That is, the liquid crystal display device according to the above method uses a MOS as a switch element for each of a plurality of pixels (liquid crystal display elements) H8 to Hn arranged in a matrix.
) active devices such as transistors and thin film transistors,
~Tn is provided, and a scanning signal X is applied to the gate of this transistor.
1,
jXYj÷+, Yjya2, . . . are applied to the liquid crystal layer from the drain of the transistor. With this type of device, the crosstalk voltage that causes contrast reduction is no longer applied to the liquid crystal layer, and the signal voltage is applied to the liquid crystal layer due to the time constant determined by the OFF resistance of the transistor and the liquid crystal placement. Therefore, high contrast and fast response can be obtained regardless of the number of scanning lines.

[Problems with conventional technology]

However, in the active matrix addressing method described above, an active element must be provided for each pixel, and therefore, for example, 240 rows, 24
For those that display a 0-column dot matrix,
It is necessary to manufacture a huge number of 57,600 active elements without defects.

However, the process of forming active elements is significantly inferior to the process of forming liquid crystal display devices in terms of yield and cost, so it has not been widely adopted.

[Purpose of the invention]

This invention was made against the background of the above-mentioned circumstances, and its purpose is to improve display characteristics such as contrast, and improve manufacturing and cost by significantly reducing the number of active elements. An object of the present invention is to provide a liquid crystal display device and a driving method thereof.

(Summary of the Invention) In order to achieve the above-mentioned object, the present invention divides at least the signal electrodes out of a plurality of scanning electrodes and signal electrodes arranged in a matrix into two or more groups, and within each group. The gist of the present invention is a liquid crystal display device in which active elements connected to each signal electrode are provided, and control terminals are provided to control the active elements on a group-by-group basis. Further, in the liquid crystal display device configured in this manner, the active elements are controlled for each group to each signal electrode, so that a display signal is sequentially applied to each group, and the display signal is applied to each signal electrode. The gist of this invention is to provide a method for driving a liquid crystal display device in which a scanning signal is sequentially applied to each scanning electrode within the group within a period of time.

〔Example〕

Hereinafter, this invention will be specifically explained based on an embodiment shown in FIGS. 2 to 5. FIG. 2 shows a matrix type liquid crystal display device, in which a liquid crystal substance 3 is sealed between a pair of substrates 1.2 arranged oppositely, and A plurality of scanning electrodes 4 and a plurality of signal electrodes 5 are disposed on the facing inner surface to form a plurality of pixels arranged in a matrix. In addition,
In the figure, 6.7 is an alignment film formed on the inner surface of the substrate 1.2.

The electrode structure of the matrix type liquid crystal display device is constructed as shown in FIG. That is, a plurality of scanning electrodes o(n)s (''≦n≦I/2) arranged in the row direction and a plurality of signal electrodes 5A (Ill), (1
≦m≦J) and a plurality of scanning electrodes 8fA0(n), (I/2
+1≦n≦t) and a plurality of signal electrodes arranged in the column direction
B(m), (1≦m≦J) and a second electrode group (group B). Paraphrase number f1
It has a matrix electrode structure divided into two groups A and B. In terms of the plane, active elements T, l(m) STB(m) are provided corresponding to the number of active elements connected to each signal electrode SA(m) and 8B(m) of each group A1B, respectively. I'll try it. In this case, a signal for controlling the gates of the transistors configuring the active elements TA(m) and TB(m) of groups A and B to control the active elements TA(m) and TB(m) as a group selection signal; That is, the control terminal T A N T to which the group selection signal X
ANB is applied via ANB. In addition, the signal electrodes SA(m) and SB(m) of each group selection signal are provided with a display signal Y(Ill).
The corresponding active elements 'I'A(m) and 'I'B(m)
is applied via.

Next, a method for driving the matrix type liquid crystal display device configured as described above will be explained with reference to FIGS. 4 and 5. 4 and 5 show driving waveforms applied to each electrode to drive the liquid crystal display device. The group selection signals XA1XB are square wave voltage signals having a period of one frame Tf, and have opposite phases to each other. and signal XA is 1
First half (1/2 frame) of one frame circumference Q'l'f tA
During this period, the active element TA (m) connected to the signal electrode 8A (m ) in group A is turned ON, and its rear half (1/2
This is a signal for QFF during frame) tB,
Also, the signal XB is during the first half tA of one frame period Tr,
Active element TB(m) connected to signal electrode SB(m) in group B is turned off.

It is also a signal for turning ON during the latter half tB. Therefore, depending on this signal XASxB, group A
, B are selectively set to the operable state. The O display signal Y(1) is a signal applied to the signal electrodes 5A(1) and 8B(1) of the group selection signal. The first half frame of one frame period Tf contains display information for sequentially time-divisionally driving the signal electric m8A(1) according to the number of scanning lines, and the second half half frame
Display information for sequentially time-divisionally driving the signal electrode 8B(1) according to the number of scanning lines is included between two frames. Note that the next frame of signal Y(1) contains information for performing gradation display.

In this way, in the first half of the group selection signal As a result of the active element TB(1) of group B being turned on, the display signal Y(1) force (is applied to the signal electrode 5B(1). As a result, the signal electrodes 5A(1), 8B(1)
The signal applied to is a signal for time-division driving as shown in FIG.

Then, during the period when the signal voltage as described above is applied to the signal electrodes 5A(1) and 8B(1), the group A,
A scanning signal is sequentially applied to each scanning electrode 0(n) and Q(n) of B in a time-division manner. FIG. 4 shows the signal electrode 8A (1)
The signal applied to the scanning signal 0(1) of the first row during the period when the signal voltage is applied to the signal electrode 8B(1)
) shows the signal applied to the scanning electrode 0 (I/2+1) of the first row during the period when the signal voltage is applied to the first row.

By applying the above-mentioned AC voltage waveform signal to each electrode, the liquid crystal is driven to display according to the magnitude of the potential difference between the two electrodes. In FIG. 4, scanning electrode C(1)
The drive voltage waveform 0 (1)-8A (1) applied to the intersection (pixel) of the signal electrode 5A (1) and the scanning electrode 0 (I/
2+1) and the signal electrode 8B(1), the drive voltage waveform 0(I/2+1)-8B(1) is shown. Here, the scan electrode C is determined by the overall effective value of each drive voltage waveform.
The intersection between (1) and signal electrode SA (1) indicates lighting, and the intersection between scan electrode 0 (I/2+1) and signal electrode SB (1) indicates lighting and extinction waveforms. ing.

In addition, as mentioned above, the signal electrodes 8A(m), SB(
In this embodiment, the times t1 and t are set as shown in FIG. That is, in order to prevent the display signal that should be applied to the display electrodes of one group from being applied to the display electrodes of the other group when the selection of group AXB is switched by the group selection signal XA1XB, the group selection signal When the signal XA falls and rises (group selection signal (SA
Display signal Y (Yn) applied to (1), 5B (1))
Set a time t when (Y(1)) becomes the ground level,
Simultaneous switching of signals XA and Y(1) is avoided.

FIG. 5 shows each voltage waveform when driving the intersection of signal electrode 5A(2) and scanning electrode 0(2), and also shows the voltage waveforms when driving the intersection of signal electrode 8B(2) and scanning electrode 0(I/2+2). Each voltage waveform when driving an intersection is shown. Here, the scanning signals applied to scanning electrodes 0(2) and 0(I/2+2) are signals whose timing is shifted by one pulse of the display signal with respect to the scanning signal shown in FIG. In this case, the driving voltage waveform 0(2)-8A(2) applied to the intersection of electrodes 0(2) and 8A(g) is a light-off waveform, and the driving voltage waveform 0(2)-8A(2) applied to the intersection of electrodes o(I/2+2) and S The driving voltage waveform 0 (I/2+2)-sB(2) applied to the intersection of ]3(2) becomes a lighting waveform.

As described above, according to the liquid crystal display device in this embodiment,
Since the dot matrix of IXJ is divided into two groups A and B, compared to the one shown in Figure 1,
The number of active elements can be significantly reduced. That is,
The method shown in FIG. 1 requires IXJ active elements, but this method requires J×2 (number of groups). Also,
Even if the number of active elements is greatly reduced in this way, by adopting the above-described driving method, it is possible to obtain a liquid crystal display device with excellent contrast display characteristics.

In the above embodiment, the display electrodes are divided in the column direction to form two signal electrode groups, but the division is not limited to this method, and the display electrodes are divided in the row direction to form two signal electrode groups. Good as a group. In addition, in the above-mentioned nine embodiments, it was arranged to divide into two groups, but it is possible to realize the number of divisions even if the number of divisions is three or more. In addition, the present invention is not limited to the above-mentioned embodiments, and can be modified and applied without departing from the scope of the present invention.

〔Effect of the invention〕

As detailed above, this invention divides a plurality of scanning electrodes and one signal pole arranged in a matrix into two or more groups, and connects each signal electrode in each group. Since the configuration includes one active element and a control terminal for controlling this active element for each group, the number of six active elements can be significantly reduced, resulting in improved manufacturing yield and cost. It becomes possible to improve the Furthermore, in the liquid crystal display device configured as described above, active elements are controlled for each group to each signal electrode, so that a display signal is sequentially applied to each group, and 1. a display signal is applied to each signal electrode. Since scanning signals are sequentially applied to each scanning electrode in the group in a time-division manner during the application period, the number of active elements can be greatly reduced and the LCD display Even if the device is a device, display speed characteristics such as mount last will be excellent.

I4. Brief Description of the Drawings FIG. 1 is a diagram showing the electrode configuration of a conventional matrix type liquid crystal display device, FIGS. 2 to 5 show an embodiment of the present invention I, and FIG. Matric! A schematic cross-sectional view of a square type liquid crystal display device, FIG. 3 is a diagram of its electrode configuration, and FIG.
FIG. 5 is a diagram showing various drive voltage waveforms.

1.2...Substrate, 3...Liquid crystal substance, 4
(0(1)) ~O(n))---Scanning electrode, 5(8A(m
), SkenB (m) ) ・−・−signal electrode, 'I'A (
Ell), TB (m)...active element, TAN
TB...Control terminal.

Patent applicant: Casio Computer Co., Ltd. Figure 1 Figure 2

Claims (2)

[Claims] (1) On an on -the -but one -pair of substrates, a pair of substrates sealed between this pair of substrates, and multiple pixels arranged in a matrix -shaped substrate are on the inner part of the pair of substrates. In a liquid crystal display device comprising a plurality of scan electrodes and signal electrodes, at least one of the plurality of scan electrodes and signal electrodes is divided into two or more groups, and within each group 1. A liquid crystal display device, comprising: an active element connected to each signal electrode; and a control terminal for controlling the active element for each group. (2) A pair of substrates arranged facing each other, a liquid crystal material sealed between the pair of substrates, and a liquid crystal material sealed between the pair of substrates, and a liquid crystal material sealed on the opposing inner surfaces of the pair of substrates to form a plurality of pixels arranged in a matrix. In a liquid crystal display device comprising a plurality of scan electrodes and signal electrodes arranged, at least the signal electrodes among the plurality of scan electrodes and signal electrodes are divided into two or more groups, and each of the group In addition to providing an active element connected to each signal electrode in the group, a control terminal for controlling the active element for each group is provided, and the active element is controlled for each group for each signal electrode. ” ′−°′ A display signal is sequentially applied to each group, and during a period in which the display signal is applied to the signal electrodes, a scanning signal is sequentially applied to each of the scanning electrodes in the group. A method for driving a liquid crystal display device, characterized in that: is applied.