JPS6167834A - Time division driving system of matrix type liquid crystal panel - Google Patents

Abstract

PURPOSE:To reduce the total cost of the whole liquid crystal display module by reducing a maximum voltage related to LSIs on the data side. CONSTITUTION:In a driving system based upon a scanning side LSI2 for applying a prescribed voltage to a scanning electrode and plural data side LSIs 3 for applying prescribed voltages to data electrodes, each output signal of one frame outputted from the LSI2 and the LSIs 3 consists of a field A and a field B following the field A. In the field B, liquid crystal driving voltage for the same display information as that of the field A is inverted at its polarity an applied to the liquid crystal and the voltage level in the field A which is applied to said scanning electrode is suppressed to the zero-level side by the voltage value (Fig. E and Fig. D) obtained by subtracting the voltage value in the field A applied to said data electrode at the ON of liquid crystal display from the voltage value in the field B applied to the data electrode at the OFF of the display. Consequently, it is unnecessary to increase the pressure resistance of many required data-side LSIs and the cost of the whole liquid crystal module can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a time-division driving system for a matrix type liquid crystal panel using TN-FEM liquid crystal.

(Prior Art) As one of the driving methods for matrix type liquid crystal panels, time-division driving is used to reduce power consumption. In this time-division driving, as shown in FIG. 3, an integrated circuit b (referred to as a scan-side LSI) that drives a scan electrode a and an integrated circuit d (referred to as a data-side LSI) that drives a data electrode C are usually integrated. Two types of LSIs are used.

On the other hand, in this type of time-division driving system, a high drive voltage is required in order to increase the display capacity of the liquid crystal panel, and for this reason, it is necessary to increase the withstand voltage of the scanning side LSI and the data side LSI. There must be.

However, increasing the withstand voltage of this type of LSI causes problems such as a decrease in the degree of integration and an increase in the number of manufacturing steps. For this reason, time-division driving methods have been proposed that aim to reduce the maximum voltage applied to the scanning side LSI and the data side LSI.

Figure 4 shows a circuit configuration related to the conventional time-division drive system,
The scanning side LSI has voltage values (v, +v, , v,
, v□) are input, and a predetermined voltage value from among these voltage values is outputted to the scanning electrode a in response to the human power signal S1. The data side LSI also has voltage values (■a+V>, V
b Vi, 2Va) are human-powered, and one human-powered signal S2
．． In response to S3..., a predetermined voltage value from among these voltage values is output to the data electrode C. (2), 1 indicates the reference voltage, and +VCC indicates the power supply voltage.

FIG. 5 is a time chart showing the basic principle of the time-division driving method, and FIG. 6 is a time chart showing an example of improving the same driving method to reduce the driving voltage.

As for the liquid crystal driving waveform, as shown in Fig. 5(D) and (E), ■A frame consists of an A field and a B field, and in the B field, the liquid crystal driving voltage for the same display information as the A field has the polarity reversed. is applied to the liquid crystal, and 1
It is AC driven within the frame.

Here, the number of scanning lines is N, and the effective value voltage applied to the liquid crystal when it is OFF is ■. F, then +0 for VOFF
Effective value voltage applied to the liquid crystal at 8 o'clock■. 8 ratio.

■. From the condition of maximizing N/VOFF, v, , vb shown in FIG. 5 are set as shown in the following equation.

In FIGS. 5(A) to 5(E), the peak value is regulated by these values, and FIG. 5(A) shows the voltage waveform applied to the scanning electrode a.

In this voltage waveform, the reference potential is vb, the peak directivity in A field lead is 2vb, and in B field lead,
The lowest value 0 port corresponding to this peak value is taken.

FIG. 5(B) shows the voltage waveform applied to the data electrode C at 08:00, and this voltage waveform takes a value of (Vb-V,) during the A field period and (Vb-V,) during the B field period. Vb+Va).

FIG. 5(C) shows the voltage waveform applied to the data electrode C in the OFF state, and this voltage waveform is as follows.

The waveform shown in FIG. 5(B) is inverted, and takes the value (Vb+VM) during the A field period, and takes the value (Vb-V,) during the B field period.

Figures 5(D) and (E) are the waveforms necessary to drive the matrix type liquid crystal panel, and Figure 5(D) is the voltage waveform applied to the liquid crystal at 08:00. This is a waveform created by subtracting the waveform shown in FIG.

Further, FIG. 5(E) shows a voltage waveform applied to the liquid crystal in the OFF state, and is a waveform created by subtracting the waveform in FIG. 5(C) from the waveform in FIG. 5(A).

In this case, the maximum voltage applied to the scanning LSI is:

2 Vb-2, and from equation (1), this value becomes considerably large as the number N of scanning lines increases.

FIGS. 6(A), 6(B), and 6(C) are time charts showing an example in which the time division driving method shown in FIG. 5 is improved to reduce the driving voltage.

Figure 6 (A) shows the voltage waveform applied to scanning electrode a, Figure 6 (B) shows the voltage waveform applied to data electrode C at 08:00, and Figure 6 (C') shows the voltage waveform applied to data electrode C when it is OFF. The applied voltage waveform is shown.

In this case, by lowering the voltage applied to scan electrode a and data electrode C by (■, -Va) during the A field period, the maximum voltage applied to the scan side LSI and data side LSI is reduced to (■, +V,). = $+ 1) v, t
The desired liquid crystal driving waveforms shown in FIGS. 5(D) and 5(E) are created. Now, assuming that the 5 scanning side LSI and data side LSI are set as a P-board and V-s-OV, then this 1. ．． is the lowest potential supplied to both LSIs.

The maximum voltage V IIaX applied to both LSIs is (■
.

+■, ), that is, (/'ii+1)v, . . . (3).

(Problems to be Solved by the Invention) However, in such a conventional driving method, the maximum voltage applied to the liquid crystal driving LSI is quite high (as a result, it cannot cope with the display capacity of the liquid crystal panel, which increases every five years).

In the present invention, the number of data-side LSIs increases as the display capacity of the liquid crystal panel increases, and the number of scan-side LSIs increases regardless of the increase in display capacity.

Considering that there is normally one LSI, the purpose is to reduce the total cost of the entire liquid crystal display module by lowering the maximum voltage related to the data side LSI.

(Means for Solving the Problems) The present invention provides a matrix type liquid crystal panel using a scan-side integrated circuit that applies a predetermined voltage to the scan electrode and a plurality of data-side integrated circuits that apply a predetermined voltage to the data electrode. This is a time-division driving method.

One frame of output signals output from the scanning side integrated circuit and the data side integrated circuit is called the A field.

gl Consists of a B field that follows the A field, and in this B field, the liquid crystal drive voltage for the same display information as the A field is applied to the liquid crystal with the polarity reversed,
Only the voltage value obtained by subtracting the voltage value of the A field applied to the data electrode when the liquid crystal display is ON from the voltage value of the B field applied to the data electrode when the liquid crystal display is ON is calculated. This invention relates to a time-division driving method for a matrix type liquid crystal panel in which the voltage level of the A field applied to the scanning electrode is reduced to zero and suppressed to the healthy side.

(Example) An example of the present invention will be described below with reference to the drawings.

FIG. 1 shows a circuit connection diagram for concretely realizing the time division driving method according to the present invention.

Is this time division drive circuit 1 a TN-FEN? [This circuit drives a matrix-type liquid crystal panel using crystals in a time-division manner, and is composed of a scanning side LSI 2 and a plurality of data side LSIs 3, and the relationship between these two LSIs and the liquid crystal panel is the same as in FIG. The scanning side LSI 2 has a voltage value (V o, V I V a > determined by a calculation formula described later) and a human input signal S1. Similarly, the data side LSI 3 has a voltage value (V s ) determined by a calculation formula described later. ,
v,, Vz) and human power signal 32. S3... are each manually operated.

In addition, in the circuit connection diagram shown in Figure 1, the case where the scanning side LSI 2 and the data side LSI 3 are P- substrates is exemplified, and the reference potential V-+ (substrate potential) of the data side LSI 3 is set to the reference potential Vs- of the scanning side LSI 2. E than z (substrate potential)
d(V) (however, O<E, <vc.-■, 5□).

Note that if both of the side LSIs are N- boards, +
VeC and liquid crystal driving voltage ■. ~■ takes a negative value, and the value of Ea also takes a negative value.

Figures 2 (D) and (E) show the liquid crystal drive waveforms necessary to drive the liquid crystal panel, and this liquid crystal drive waveform is A
One frame consists of a field and a B field. In the B field, a liquid crystal drive voltage for the same display information as in the A field is applied to the liquid crystal with its polarity reversed, and the liquid crystal is driven with alternating current within one frame.

The v8 value and the ■ゎ value in the figure are values determined by the same relational expression as the above-mentioned expression +11 [21.

FIG. 2(A) shows the voltage waveform applied to the scanning electrode a, and FIG. 2(B) shows the voltage waveform applied to the data electrode C when turned on.
The figure <C> is the voltage waveform applied to the data electrode C when it is OFF, and the figure CD) is the voltage waveform applied to the liquid crystal when it is ON. This is a waveform created by subtraction.

Further, (E) in the same figure is a voltage waveform applied to the liquid crystal when the liquid crystal is turned off, and is a waveform created by subtracting the waveform in (C) in the same figure from the waveform in (A).

In the present invention, in order to obtain the desired voltage waveforms shown in FIG. ■4, which is lowered by ■4 given by , is taken as the reference level.

V4 = Vb Va Eg - f4) That is, Vss+ = Ea, Vgr2 = O, and the liquid crystal driving voltage (VO
.

VS, V4) and the liquid crystal driving voltage (V+, Vl vs) supplied to the data side LSI 3 are expressed by the following formula.

■. =2Vb Va= (FJ+ 1) Va+Ea
V,=V,-V.

V2= ■, + v, Va= 2'VM + E
av,=v,=,6v.

V 4 = V b Va = Va + E
aV5=Vb+Vs=$+1)Va The voltage V0 supplied to the scanning side LSI 2 is the peak value in the A field of the voltage waveform applied to the scanning electrode a, and the voltage 4 is the reference level in the A field. .

The voltage V supplied to the data side LSI 3 indicates the voltage during the B field period of the voltage waveform applied to the data electrode C when it is ON, and the voltage V indicates the B field period of the voltage waveform that is applied to the data electrode C when it is OFF. .

Indicates the voltage of the period, voltage 2 is A in the same voltage waveform.
Indicates the voltage during the field period.

(Specific Data) According to the present invention, the maximum voltage V applied to the data side LSI 3
Assuming that DM is V-*+-Ea and Vs-i=0.

VDM=VS V*g+-(,/'jM+ 1) V
a E, +, and the maximum voltage v3M applied to the scanning side LSI 2 is.

Vs, 4= Vo Vssz= (仄”1) V
It becomes a + Ea.

Now, the number of scanning lines N=64. Liquid crystal threshold voltage Vvh=
Take a 2.0 (V) matrix type liquid crystal panel as an example.

As VOFF = Vth = 2.0 (V).

From formula (1).

V, = 1.512 (V).

Therefore, in the conventional method, Equation 1 (3) is used.

■□. =13.61 (V), and it is necessary to make both the 5-scan side LSI and the data side LSI high withstand voltage.

On the other hand, in the above embodiment, if E = 3.608v, the maximum voltage VDM applied to the data side LSI becomes IOV, and the maximum voltage v3.4 applied to the scanning side LSI becomes 17.22V. Therefore, there is no need for the data side LSI to have a high breakdown voltage.

(Effects of the Invention) As described above, according to the present invention, there is no need for the data-side LSIs, which are required in large numbers, to have particularly high voltage resistance, thereby reducing the total cost of the entire liquid crystal module. I can do it.

[Brief explanation of drawings]

Fig. 1 is a wiring circuit diagram of an LSI for realizing the time-division driving method according to the present invention, Fig. 2 is a timing chart explaining the operation of the embodiment, and Fig. 3 is a matrix type liquid crystal panel and an LSI for driving liquid crystal. 4 is a block diagram showing the relationship between the
5 and 6 are timing charts explaining the operation of the conventional example. ■...Time division drive circuit 2...Scanning side LSI3...
・Data side LSI and 1 other person Figure 7

Claims (1)

[Scope of Claims] 1) A method of time-divisionally driving a matrix type liquid crystal panel using a scanning-side integrated circuit that applies a predetermined voltage to the scan electrode and a plurality of data-side integrated circuits that apply a predetermined voltage to the data electrode. One frame of output signals output from the scanning-side integrated circuit and the data-side integrated circuit consists of an A field and a B field following the A field, and in this B field, the liquid crystal drive voltage with respect to the A field is The voltage value of the A field applied to the data electrode when the liquid crystal display is ON is subtracted from the voltage value of the B field, which is applied to the liquid crystal with the polarity reversed and applied to the data electrode when the liquid crystal display is OFF. 1. A time division driving method for a matrix type liquid crystal panel, characterized in that the voltage level of the A field applied to the scanning electrode is suppressed to the zero level side by only the voltage value corresponding to the voltage value.