JPS5941196B2 - LCD drive method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for driving a liquid crystal.

The conventional liquid crystal driving method uses a circuit as shown in Figure 1, and a pulse signal N is applied to the common surface side 1 of the liquid crystal, and this N and segment signals are applied to the segment sides 2, 3, etc. Connect the outputs of exclusive OR 4, 4, . . . with the drive signal. Then, when each segment drive signal comes to terminals 5, 6, etc., the exclusive OR output is N
A signal N having a phase shift of 1800 is applied to segments 2, 3, etc., and lights up the liquid crystal. In order to dynamically light up the liquid crystal using this method, a circuit as shown in FIG. 2 is required.

That is, a pulse N is applied to the common surface side 1 of the liquid crystal via an inverter □, exclusive ORs 8, 8, and so on.
Exclusive OR 8, 8's other input terminal 9, 9...
Digit selection signals D1, D2, . . . are added to . FIG. 3 shows the operation of the circuit of FIG. 2. A pulse 11 with an amplitude V is applied to the liquid crystal common surface side by a digit selection signal 10, and a segment drive signal 12 applied to terminals 5, 6, . . .
3 is applied with a pulse 13 having an amplitude V. Therefore, a voltage 14 is applied to both sides of the liquid crystal. A voltage 14 is applied to both sides of the liquid crystal. When the voltage applied to both sides of the liquid crystal is -V, the light is on, and when the voltage is 0, the light is off. However, if the digit selection signal 10 is N, if the segment side is N, the voltage will be V and the liquid crystal will turn on, and if the segment side is N, the voltage will be O and the liquid crystal will turn off. Even when the segment side is N, the lighting 9' in Figure 3,
There was a drawback that it lit up like 6'. The present invention eliminates the drawbacks of the conventional methods as described above and provides a method that facilitates dynamic lighting of a liquid crystal. FIG. 4 is a diagram showing the relationship between voltage and transmittance characteristics of liquid crystal.

Here, the voltage is the voltage applied between the segment side and the common side of the liquid crystal, and the transmittance is the percentage of light incident on the surface of the liquid crystal that is transmitted through the liquid crystal. The larger the percentage, the darker the image, and the smaller the percentage, the brighter the image appears. From this diagram, it is clear that if a voltage of V1 is applied, the lamp will turn on, and if a voltage of V2 is applied, the lamp will turn off. The present invention applies this principle, and one embodiment of the present invention will be described below with reference to the drawings.

In FIG. 5, there are many segments on the opposite side to the common surface side 1 of the liquid crystal. , is provided. Voltages (-V3), (+V3), (-V4), and (+V4) are supplied to the first to fourth power supply terminals 41, 42, 43, and 44, respectively, and the common surface side 1 of the liquid crystal 0V is supplied. Then, set the threshold voltage of the liquid crystal to Vth
When V3>Vth>V4, Vth>V3-V4
It is assumed that the relationship is as follows. An n-channel MOS transistor (hereinafter referred to as n-MO) is connected between terminals 41 and 42.
)54, n-MOS5l, p-channel MOS
Transistor 52 (hereinafter referred to as p-MOS), p-MO
S55 are connected in series to constitute the first inverter 53. The gates of the NMOS 5l and the p-MOS 52 are connected in common to the input terminal 4 of the first inverter 53.
5, and the commonly connected sources and drains of the two transistors serve as an output point 46 of the first inverter 53. Between the terminals 43 and 44, n-M
OS59, n-MOS56, PMOS57, p-MOS
A second inverter 58 consisting of 6O is configured,
The gates of the n-MOS 56 and p-MOS 57 are both connected to the input terminal 45 of the first inverter.
The commonly connected sources and drains of the two transistors are connected to the output point 46 of the first inverter 53 and to one of the segments 2 of the liquid crystal. n-MOS54 and p-M
The segment drive signal A is supplied to the gate of the OS6O, and the inverted signal of the segment drive signal A is supplied to the gates of the n-MOS 59 and the p-MOS 55 at the power supply voltage (-V3).
It is supplied via an inverter 47 using (+V3). In the above configuration, a voltage of (-V3) is applied to all of the n-MOS sub-slates, and a voltage of (+3) is applied to all of the p-MOS sub-slates. In such a circuit, segment drive signal A is (+V
3) When it becomes n-MOS54 and p-MOS55
becomes 0N, and n-MOS59 and p-MOS6O become 0F.
F, and the segment side of the liquid crystal has (+V3) and (-V
A liquid crystal drive signal N having an amplitude of 3) appears, and the liquid crystal lights up.

Further, when the segment drive signal is (-V3), the n-MOS 54 and the p-MOS 55 are 0FF. n-MOS59
, p-MOS6O is turned on, a signal with the same phase as above and amplitudes of (+V4) and (-V4) is applied to the segment side, and the liquid crystal turns off. FIG. 6 shows an embodiment of a dynamic lighting circuit according to the present invention to which the above circuit is applied. In Figure 6, segments 2, 3...2
, 3, . . . side circuits are the same as those shown in FIG. A digit selection circuit 61 is provided on the common surface 1, 1 of the liquid crystal of each digit.
The output 62 of is connected. This digit selection circuit 61 selects n-
n-MOS with MOS63 and p-MOS64 connected between their respective drains and power supplies (-V3) and (+V3)
65 and a p-MOS 66, and the output of this inverter 67, that is, the output 62 of the digit selection circuit, and the G
It consists of a p-MOS68 connected between ND. Next, the operation of the present invention configured as described above will be explained with reference to the operation example shown in FIG.

N is the input terminal 4 of the inverters 53 and 58 on the segment side
5 and the liquid crystal drive signal applied to the input terminal 48 of the inverter 67 on the common surface 1 side. When the digit selection signal D1 is +V3, the n-MOS 63 and p-MOS 64 become 0FF, and the p-MOS 68 becomes 0N, so the common surface side 1 of the liquid crystal
The voltage D1 applied to is O. When scolded, the fifth
The state is the same as the circuit shown in the figure, and as shown in Figure 7, when the segment drive signal A is (+V3), the voltage A applied to the segment side is 71, and the voltage A applied to both sides of the liquid crystal is Since the voltage A applied is (±V3) as shown in 72, the liquid crystal is lit. And the segment drive signal A is (-
V3), the voltage A becomes 73, and the common surface side 1
A voltage of (±V4) is applied between the segment side 2 and the segment side 2, and the liquid crystal turns off. Next, when the digit selection signal D1 is (-V3), n-MOS63, p-MOS64
becomes 0N, and the p-MOS 68 becomes 0FF.

Therefore, a voltage 74 having the same phase as the segment side and amplitudes (+V3) and (-V3) is applied to the common surface side 1 of the liquid crystal, and the voltage A applied to both sides of the liquid crystal is 75 or 76. Since the voltage is less than Th, the light is turned off regardless of the segment drive signal A. As described above, the present invention has the effect of enabling dynamic lighting of a liquid crystal with a simple configuration.

Further, in the above embodiments, the case where a reflective liquid crystal is turned on has been described, but it goes without saying that the same can be said for a transmissive liquid crystal.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional liquid crystal drive circuit, Fig. 2 is a block diagram of a liquid crystal dynamic drive circuit to which Fig. 1 is applied, and Fig. 3 is a diagram for explaining the operation of Fig. 2. FIG. 4 is a diagram for explaining the principle of the present invention, FIG. 5 is a block diagram of one embodiment of the liquid crystal driving method according to the present invention, and FIG. 6 is a diagram showing one implementation of the liquid crystal dynamic driving method according to the present invention. An example block diagram, FIG. 7, is a diagram for explaining the operation of FIG. 6. 1... Common surface side of the liquid crystal, 2, 3... Segment side of the liquid crystal, 41, 42... Power terminal that supplies voltage to light the liquid crystal, 43, 44・・・・・・
・Power terminal that supplies voltage to turn off the liquid crystal, 54, 5
1, 59, 56, 63, 66...N channel MOS transistor, 52, 55, 57, 60, 66,
64, 68...P channel MOS transistor 53,...First inverter, 58...
...Second inverter, 45...First and second
gate input terminal of the inverter, 46...first
and a common output point of the second inverter.

Claims (1)

[Claims] 1 In a method of driving a liquid crystal display element in which a liquid crystal is interposed between a first electrode and a second electrode and has a threshold voltage Vth, V_3>Vth>V_4>0 and V
Power supply voltage level + with the relationship th>V_3−V_4
V_3, -V_3, +V_4 or -V_4 is selectively supplied to the first electrode to set the voltage level +V_3, -V_3.
, or an intermediate potential thereof is selectively supplied to the second electrode, and the display element is activated only when the voltage level +V_3 or -V_3 is supplied to the first electrode and the intermediate potential is applied to the second electrode. A liquid crystal driving method that has a receiving polarity voltage level characterized by being lit.