JPS60173522A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To suppress a required power source at the two levels common with a logic circuit and to obtain the voltage waveform to increase an effective voltage ratio by adding a low level voltage to a segment signal when the logical multiple sum is odd for the period of >=2/3 of the same common timing period and a high level voltage thereto when said sum is even. CONSTITUTION:Three common lines (X,Y,Z) take the voltage levels to repeat periodically eight-ways of combinations (A,B,C) including (0,0,0), (0,0,1), (0,1,0), (0,1,1), (1,0,0), (1,0,1), (1,1,0), (1,1,1). On the other hand, the level taking the law of impressing a low level voltage V0 when the logical sum is odd and a high level voltage V1 when said sum is even is impressed to the segment line by 2/3 of the same common timing period when the logical sum (X+Y+Z)+(A+B+C) is ''1'' or ''0'' and another level is impressed for the remaining 1/3 thereto. The effective voltage to be impressed to a selection part is larger than in the prior art in this case as well.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a liquid crystal display device. Particularly related to a simplified dynamically driven liquid crystal display device (prior art) Conventional dynamic drive circuits for liquid crystal display devices generally use the 1/2 bias method, the 1/3 bias method, or the 1/N bias method.
The bias method has been recognized as a method suitable for improving display contrast.

FIG. 1 shows voltage waveforms at each terminal for 1/3 bias and 1/5 duty drive, which are often used as dynamic and drive waveforms for liquid crystal displays for calculators. In this waveform, the ratio of the effective voltage of the ON segment part to the effective voltage of the OFF segment part is relatively large at 1.91'5,
Since four voltage levels of vQ + "I H" 2 Hv3 are required, (1) each voltage level is boosted or created by resistance division, resulting in power loss. Therefore, it is disadvantageous when using the smaller, cheaper batch IJ-19, such as a solar powered calculator.

(2) Since each voltage level is required, all analog switches are attached to each output terminal section as a driving circuit, which increases the circuit load.

(3) Capacitors, resistors, etc. are required for boosting and voltage division, which increases the cost of electronic components.

(4) Since the effective voltage applied to the lighting segment is as small as 0.638V3 compared to the highest voltage level (v3),
It is necessary to supply a fairly high voltage, and in the case of solar calculators, the number of solar batteries increases, which is a factor in increasing costs.

(Purpose) The purpose of the present invention is that the required power supply is two parts common to the logic circuit section.
The object of the present invention is to provide a voltage waveform that suppresses the voltage level and increases the effective voltage ratio, thereby eliminating the above-mentioned drawbacks.

(Structure) The liquid crystal display device of the present invention uses five common lines (x, y , z), the combination of voltage levels at each timing is (0,0+0)1(0+0+1)+(0+'
yO)+(0+'p')p('+ ro, ro), (1
, ro, 1).

(1, 1, mouth), (1#1.1), (where 1 indicates the high level side voltage and 0 indicates the low level side voltage), and each common line is connected to the segment line. for (ON or OFF, ON or OFF, ON or 0
The 8 combinations of FF) are represented by (A, B, C), and A, B, and C are each represented by 1 or 0, and 1 is ON.
state, 0 indicates OFF state), (X* Y+ z
) = (Ar1.C), the low level voltage is set to (x
,y.

) = (A+BtC), apply a high level voltage, otherwise apply a low level voltage when the logical majority sum (x+y+Z0A0B+C) is an odd number, and apply a high level voltage when it is an even number. This is in addition to the segment signal for a period of two-thirds or more of the timing period.

(Embodiment) FIG. 2 is an example of a voltage waveform for a 1/3 duty multiplex drive configured with only two levels based on the present invention.

The rules for the waveform combination are as follows.□Now,
3 common lines, common 1. Expressing the states of common 2 and common 5 by (X, Y, z), (X or Y or 2 =
When it is 0, it indicates a low voltage level vo, and when it is X or Y or Z
= 1 indicates a high voltage level v1), the combination of x, y, z is not necessarily present between one frame or two positive and negative frames (Ro, Lo, 0), (0, 0, 1)
There are 8 ways: l (0', 1 t-5 = 0) + (CI + 1.1) + (1 + " + 0) s (1 + mouth・1) + ('l'IO) + ('l'91) The voltage waveforms are assembled so that the voltage waveforms are generated.At this time, the order of combination may be arbitrary.

On the other hand, the driving voltage waveform of the segment line for this can be considered to have 8 combinations depending on the selection (lighting ON state) or non-selection (lighting OFF state) for the commons 1, 2s, and 3. Combine as shown in the table. H in the table is the high level side voltage (V 1
), and L indicates a low level voltage (V, ).

6- Table 1 In the case of (A, B, a) = (o, o, o) in Table 1, the segment line is not selected (non-selected) for any of the commons 1° and 2.3. (lit), (A , B
, 0) = (0, 0, 1), the segment line is non-selected (not lit) for commons 1 and 2, selected (lit) for common 3, (A ,B,O)
:(1.

In the case of 1.1), the segment line is common 1,
The case where both 2.3 are selected (lit) is shown. An example of the waveform expressed based on Table 1 is shown in FIG.

For example, in the case of segment line Kakomo 71, 2, 517C and oyy, oyF, oyp) switching (0, 0, 0), the temporal K(x, y, z
) is H-+ in the (1,1°1) → (-0, 0, 0) direction
l→H-+L-+H→L→L-+L11Ii:

This regularity is expressed as (1) (X, Y, Z) = (A, B
, O), then L (low level voltage: Vo) is applied.

(2L If (X, Y, Z) = (A, B, O), apply H (high level voltage: VI).

(3) In cases other than the above, apply L (low level voltage: Vo) when the logical sum (x+y1z)+(A0B+O) is an odd number, and apply H (high level voltage; V,) when it is an even number. do.

The above regularity forms the waveform logic shown in the first layer.

When calculating the effective voltage of the drive according to the present invention, the selection part (O
The effective voltage (VON) applied to the N section is Vt -
As Vo = v, VON: Jr\-v = Q, 866v Effective voltage applied to non-selected part (OFF part) K (VOFF
) is VOFF = JTV = [15V Therefore, the effective voltage ratio VON/VOFF is voM/Vory = ig = 1.732 Comparing this value with the conventional drive method, both cases are 1/3 duty, and the second It is as shown in the table.

Table 2 - Figure 3 shows another specific driving waveform of the present invention, in which the common line is the same as in the previous embodiment [three lines are (0, 0, 0), (0,0°1), (0,1,0)
, (0,1,1), (1°0.0), (1,0,1),
A voltage level is taken that periodically repeats eight combinations of (1, 1, 0) and (1, 1, 1). On the other hand, the segment line has two cases: (X, Y, Z) = (A, B, O) and (X
, Y, Z) = ('A-, 13, O), it is the same as the previous example, but for other logical sums (
X0Y-1-Z)+(A1B-1-0) is 1 or 00
Sometimes, for two-sixths of the same common timing period, a level following the rules of the previous embodiment is applied, and for the remaining one-third, the other level is applied. In this case, each effective voltage and its ratio are VON = n V = 0.816 VVow F =
/V :0577V voN/Voyy = p = 1.414.

In this case as well, the effective voltage of 70M is significantly lower than that of the conventional method.
- become louder.

Note that it is of course possible to expand the technical idea of the present invention and drive with a tool duty, tool duty, viewing duty, etc. 4. The present invention can be applied to both segment type and matrix type.

(Effects) Next, the effects of the present invention can be summarized as follows: (1) Supply! Since only two pressure bells are required, the negative power supply can serve both as the logic circuit and the liquid crystal display drive power supply. Therefore, 6
Step-up or resistance division to create 4 levels is unnecessary. 9. Wasted power and capacitors for that purpose.

Electronic components such as resistors can be saved.

(2) The effective lighting voltage with respect to the supply power supply voltage vVc is high (
0.8/+6V), the liquid crystal display can be driven with a relatively low voltage power supply, so the number of batteries can be reduced. Particularly in the case of solar battery drive, the number of solar battery panels can be saved.

(3) Based on the above-mentioned technology, by using the driving method of the present invention, it is possible to provide a liquid crystal display device driven by a 1.5V power supply without boosting the voltage.
The power consumption is reduced, making it possible to reduce the cost of calculators and watches in particular, and extend the lifespan of batteries.

[Brief explanation of the drawing]

Figure 1 shows an example of the voltage waveform of a conventional dynamic drive with a 1/6 duty and a 1/5 bias. FIG. 2 is an example of a driving voltage waveform of a 1/3 duty liquid crystal display device based on the present invention. FIG. 3 shows another embodiment according to the present invention. Applicant Epson Corporation Agent Patent Attorney Mogami Figure 1 VS :Jt:zl (OFF) VS ``Mole 2 (OFF) vs Common + (ON) Vj Common z -Co (OFF) vs Common'' (OFF) tfj>MON, ON, OFF>Y;”9.~1μ
1111 side a (ON) VS a72 (ON) VS common l (ON)! S Common 2 (ON) vs Common J (ON) Fig. 2

Claims (1)

[Claims] In a liquid crystal display device that uses multiplex drive with a duty ratio of 1:5, the three common lines (x, y, z) have three common lines (x, y, z) as applied voltage waveforms for display drive. The combination of voltage levels for each timing (mouth + 0 + 0)
t("+"+')+("+'+0)+(ro+'
s' ) * ('+”+ OL('+0+')+
('+'+0)+(1+1+')+(here, 1 indicates the high level side voltage and 0 indicates the low level side voltage), and each common line has each common line on the segment line. For the line (ON or OFF, ON or O
FF, ON or 0FF) in 8 combinations (A,
B. (X,
At the time of Y, Z) - (A, B, C), low level voltage,
When (X+ Y+ z) = (A+ BrC), a high level voltage is applied, and at other times, a logical majority phase (X
+Y+Z+A+B+C) is an odd number, a low level voltage is applied to the segment signal, and when it is an even number, a high level voltage is applied to the segment signal for at least two-thirds or more of the same common timing period.