JPS623426B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for driving a liquid crystal display device that displays bar graphs and the like.

Conventionally, there have been devices that statically drive a liquid crystal display device to display an integrated value such as a bar graph in the following manner. As shown in FIG. 9, a polarizing plate A is sandwiched between two sets of liquid crystal panels P ₁ and P ₂ , and two polarizing plates A and A are provided on the outside. Each polarizing plate is
Assume that they have parallel polarization axes. A common electrode C ₀ is connected to the glass substrate G ₁₀ of the liquid crystal panel P ₁ , and the liquid crystal
Five divided electrodes C _{1 .} . . C ₅ are formed on the glass substrate G ₂₀ facing each other via LC ₁ . In addition, the above-mentioned divided electrodes are installed on the glass substrate G ₃₀ of the liquid crystal panel P ₂ .
Divided electrodes C′ ₁ ………C′ ₅ similar to C ₁ ………C ₅ are connected to each of the divided electrodes C′ ₁ ………C′ ₅ on the glass substrate G ₄₀ via a liquid crystal LC ₂ . 10 divided electrodes S ₁ . . . S ₁₀ are formed in a zigzag pattern.

Note that the liquid crystals LC ₁ and LC ₂ are both of twisted nematic type.

Further, the divided electrodes C _{1 .} . . C ₅ are connected to the divided electrodes C' ₁ . . . C' ₅ , respectively.

In the above configuration, the common electrode C ₀ is always maintained at a voltage of 0, as shown in the column of FIG. On the other hand, the divided electrodes C ₁ ......C ₅ and C' ₁ ......
The example voltages 0, V, and 2V (V is the saturation voltage of the liquid crystal) are selectively applied to _C'5 in common, and the divided electrodes _S1 ...
...By selectively applying column voltages V and 3V to _S10 , bar graph display is performed. For example, if you want to display the number 15, use the split electrode
A voltage of 2 V is applied to C ₁ and C′ ₁ , and a voltage of V is applied to divided electrodes C ₂ and C′ ₂ .
, a voltage of 0 is applied to the divided electrodes C ₃ ......C ₅ , C' ₃ ......C' ₅
Apply. As a result, voltages of 2 V and V are applied to the liquid crystal LC ₁ facing the divided electrodes C ₁ and C ₂ , and in response, the long axes of the molecules are aligned in the direction of application of the electric field. Further, the voltage applied to _{the liquid crystal LC 1 facing} the divided electrodes C ₃ . Since the polarization axes of the polarizing plates A and A are parallel, light does not pass through the display area formed by the divided electrodes _C3 ... _C5 , that is, the scales 21 to 50, and becomes dark regardless of the state of the liquid crystal _LC2 . . Also split electrode
Display area by C ₁ and C ₂ , i.e. scale 0 to 20
allows light to pass through.

On the other hand, in order to darken the display area of scales 16 to 20, a voltage V is applied to the divided electrodes S ₁ ...... S ₅ corresponding to this area, and a voltage of 3 V is applied to the divided electrodes S ₆ ...... S ₁₀ .
Apply. _{As a} result, _the voltage V _, -
V is applied and responds, and a voltage of 2V is applied to the liquid crystal LC ₂ between the divided electrode C' ₂ and the divided electrodes S ₆ . . . S ₁₀ and responds. Further, the voltage applied to _the liquid crystal LC ₂ between the divided electrode C' ₂ and the divided electrodes S ₁ .

Therefore, the display area of scales 0 to 15 becomes brighter, and the area of scales 16 to 50 becomes darker.
15 is displayed.

Because of the above, the voltage applied to the electrodes is at most three times the saturation voltage V of the liquid crystal.
3V is required, and in addition, voltages V and 2V are required, which makes the power supply circuit complicated and undesirable.
Further, in the region where voltages of 2V and 3V are applied, power is wasted, resulting in an increase in power consumption. Moreover, the contrast of the regions to which the voltages V, 2V, and 3V are applied differs slightly, and uniform display is not performed.

In addition, the structure was undesirable as it required four glass substrates and three polarizing plates, was thick, and caused errors depending on the viewing angle when reading the scale.

Furthermore, alignment when two liquid crystal panels are combined is complicated.

Therefore, the present invention provides an integrated display using a thin liquid crystal display device in which a liquid crystal panel in which liquid crystal is interposed between first and second transparent substrates and second and third transparent substrates is sandwiched between two polarizing plates. This is to eliminate the above-mentioned drawbacks of the conventional method.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Fig. 1 shows a bar graph meter that displays temperature, voltage, etc., and as shown in Fig. 2, it consists of two polarizing plates A and B having polarization axes perpendicular to each other, and a first and a second polarizing plate.
and three glass substrates G ₁ , G ₂ , G ₃ constituting the third transparent substrate, and a twisted nematic liquid crystal interposed between the glass substrates G ₁ , G ₂ and between the glass substrates G ₂ , G ₃ . It consists of LC ₁ and LC ₂ . L is a light source such as a fluorescent lamp. Glass substrate G ₁ , G ₂ , G ₃
The electrodes are formed as shown in FIG. A common electrode _C0 is formed on the glass substrate _G1 , and divided electrodes _C1 ...... _C5 forming the first divided electrode are formed on the surface of the glass substrate _G2 facing the liquid crystal _LC1 . On the back side, there are divided electrodes that constitute a second divided electrode having exactly the same shape as divided electrodes C ₁ ...... C ₅ .
C' ₁ ......C' ₅ is formed. The glass substrate G ₃ has divided electrodes S ₁ ...... S ₁₀ that constitute the third divided electrode.
are formed in a zigzag pattern so as to face each of the divided electrodes C' ₁ . . . C' ₅ .

FIG. 4 shows the pulses applied to each electrode of the liquid crystal panel and the resulting pulses applied to the liquid crystals LC ₁ and LC ₂ . In the same figure, X,
Y and Z are constant cycle pulses of the same waveform, each with a phase shift of 1/3 cycle. Common electrode C ₀
A pulse X is constantly supplied to the circuit as shown in the same column. On the other hand, the divided electrodes C ₁ ......C ₅ have
Pulses Y and X are selectively supplied in a row, and Y and X are selectively supplied in a row to the divided electrodes C' ₁ . . . C' ₅ . Further, pulses X and Z are selectively supplied to the divided electrodes S ₁ . . . S ₁₀ in a row.

By supplying the above pulses, pulses, Y, and voltage 0 are selectively applied to the liquid crystal LC ₁ , and in each application state, the liquid crystal LC ₂ receives pulses X, ..., Z, voltages 0, pulse, Z is selectively applied. First, the case where the voltage applied to the liquid crystal LC ₁ is 0 will be described. At this time, the liquid crystal LC ₁ is kept in a non-responsive state, and the long axis of its molecules is twisted by 90°. On the other hand, the divided electrode C′ ₁ ...
...When a pulse is supplied to C' ₅ and one of the pulses X, , Z is applied to the liquid crystal LC ₂ , the liquid crystal
LC ₂ responds and the long axis of the molecule aligns in the direction of the applied electric field. Therefore, the light that has passed through polarizing plate _B in _FIG . It will be in display state.

Further, when the pulse X is supplied to the divided electrodes C' ₁ . . . C' ₅ , either the voltage 0, the pulse, or Z is applied to the liquid crystal LC ₂ . When this applied voltage is 0, the liquid crystal LC ₂ is also in a non-responsive state, and the long axis of its molecules is twisted at 90 degrees.

Therefore, the light that has passed through the polarizing plate B is divided into liquid crystals LC ₂ ,
They are each rotated by 90 degrees by LC ₁ , are blocked from passing by polarizing plate A, and are displayed darkly, resulting in another display state.

On the other hand, when the pulse Z is applied to the liquid crystal LC ₂ , the liquid crystal LC ₂ responds and the display area becomes brighter, resulting in one display state.

Next, we will discuss when a pulse Y is applied to the liquid crystal _LC1 . At this time, the liquid crystal LC ₁ responds and the long axis of the molecules aligns in the direction of application of the electric field. On the other hand, when any of the pulses X, . . . , Z is applied to the liquid crystal LC ₂ , the liquid crystal LC ₂ responds. Therefore, the light that has passed through polarizing plate B passes through liquid crystals LC ₂ and LC ₁ as it is, and is blocked by polarizing plate A from passing through.
This display area becomes dark and enters another display state.
Furthermore, when the voltage applied to the liquid crystal LC ₂ is 0, the liquid crystal LC ₂ is in a non-responsive state, and the light that has passed through the polarizing plate B is reflected in the liquid crystal.
After being rotated by 90 degrees by LC ₂ , it passes through liquid crystal LC ₁ and polarizing plate A, becomes brighter, and enters a single display state.
Furthermore, when a pulse Z is applied to the liquid crystal LC ₂ , the liquid crystal LC ₂ responds and displays a dark image.

As described above, light passes through only when the voltage applied to either one of the liquid crystals LC ₁ and LC ₂ is 0, resulting in a bright display.

FIG. 5 shows a circuit for applying the pulses X, Y, and Z to each electrode. In the same figure,
1 and 2 are data generation circuits, which respectively control temperature and
It receives data such as voltage and generates the 1st and 10th places using binary coded decimal power. 3 is a timing pulse generator whose output terminals 3a,
Pulses X, Y, and Z are generated at terminals 3b and 3c, respectively, and the output from terminal 3a is supplied to common electrode _C0 in FIG. 2. 4 is a conversion circuit consisting of a gate circuit, etc., and its output terminal 4a
...... 4j, pulses Z and X are generated as shown in FIG.
is generated. Reference numeral 5 denotes a control circuit consisting of a gate circuit, etc., which receives the output from the data generation circuit 2, and when the 10th place of data is 0, 2, or 4, output terminals 5a...5j are connected to terminals 4a...
...generates a pulse from 4j, the 10th position of the data is 1,
3, pulses are generated from the terminals 4j...4a to the output terminals 5a...5j, respectively.
The output terminals 5a...5j of the control circuit 5 are connected to the divided electrodes _S1 ... _S10 in FIG. 2, respectively. The reason why the connection relationship between the terminals 4a to 4j and the terminals 5a to 5j is reversed every 10 scales using the control circuit 5 is because the divided electrodes _S1 ... _S10 are wired in a zigzag pattern. be. That is, scales 1 to 10, 21 to 30, and 41 to 50 are respectively displayed by the divided electrodes _S1 ... _S10 , but scales 11 to 20, 31 to 40 are different from the above. On the contrary, this is because they are displayed by the respective divided electrodes S ₁₀ ......S ₁ . For example, scale 1-10
When displaying sequentially, as described later,
Pulse X is applied to divided electrodes S ₁ ......S ₁₀ in this order.
However, when displaying scales 11 to 20, the positional relationship of the divided electrodes S ₁ ......S ₁₀ corresponding to these scales is reversed, so it is different from the above. On the contrary, this is because the pulse X must be sequentially supplied to the divided electrodes S ₁₀ . . . S ₁ in this order.

The reason why the divided electrodes S ₁ ......S ₁₀ are connected in a zigzag manner is to prevent the wiring from crossing.
This is a conventional technique in the art.

Reference numeral 6 denotes a conversion circuit consisting of a gate circuit, etc., which generates pulses X and Y at output terminals 6a, . . . , 6e, respectively, as shown in FIG. Conversion circuit 6
The output terminals 6a...6e of the output terminals 6a...6e are respectively connected to the selection electrodes _C1 ... _C5 of FIG. 7
8 is a conversion circuit consisting of a gate circuit, etc., and generates pulses X and Y at its output terminals 7a, . . . , 7e, respectively, as shown in FIG. Output terminal 7a of conversion circuit 7
. . . 7e are connected to the divided electrodes C' ₁ . . . C' ₅ , respectively.

Next, the operation will be explained. For example, a case where 15 scales are displayed will be explained. In this case, a pulse X is output from the output terminal 6a of the conversion circuit 6.
However, the pulse Y from the terminals 6b...6e is the seventh
The divided electrodes shown in Figure 2 are generated as shown in the figure, respectively.
C ₁ ......supplied to C ₅ . Therefore, as shown in Figure 4, the applied voltage between the common electrode C ₀ and the divided electrode C ₁ is 0.
Therefore, a pulse Y is applied between the common electrode _C0 and the divided electrodes _C2 ... _C5 .

On the other hand, from the output terminals 7a...7e of the conversion circuit 7, pulses Y, X,
Y, Y, Y are generated, and the divided electrode C' ₁ in Fig. 2...
…supplied to C′ ₅ . Furthermore, a pulse
A pulse Z is generated from f...4j as shown in FIG. On the other hand, due to the output of data 1 from the data generation circuit 2, the output terminal 5a of the control circuit 5...
...5j are respectively connected to the terminals 4j in Fig. 6...4
Pulses from a are generated and are respectively supplied to the segmented electrodes S ₁ . . . S ₁₀ of FIG.

That is, the pulse Z is supplied to the divided electrodes _S1 ... _S5 , and the pulse Z is supplied to the divided electrodes _S6 ... _S10 .

On the other hand, as mentioned earlier, the divided electrodes C′ ₁ , C′ ₃ ,
Since the pulse Y is supplied to C' ₄ and C' ₅ , the pulse Z is applied between these and the divided electrodes S _{1 .} . . S ₅ as shown in Fig. 4, and the divided electrodes S ₆ . ...S ₁₀
A pulse X, is applied between. Furthermore, since the pulse X is supplied to the divided electrode C′ ₂ as described above, the voltage applied between this and the divided electrode S ₆ ......S ₁₀ becomes 0, and the voltage applied between this and the divided electrode S ₁ ......S A pulse, Z, is applied between 5 and ₅ .

Therefore, the applied voltage is 0 only between the supply electrode C ₀ and the divided electrode C ₁ and between the divided electrode C′ ₂ and _the divided electrode S ₆ . That is, the 1st to 15th scales are displayed brightly.

As described above, the integrated display is performed in accordance with the data from the data generating circuits 1 and 2.

In this way, by selectively supplying pulses with the same waveform but different phases to each electrode for integrated display, it is only necessary to supply pulses with a fixed period with a shifted phase, and the voltage of the pulses can be reduced. Since it is constant, the circuit configuration becomes simple.

Further, as described above, if the duty of the pulses X, Y, and Z is reduced to 1/3, the duty of the pulse applied to the liquid crystal becomes 2/3. Therefore, the voltage V ₀ of this pulse is set so as to satisfy the formula 2/3·V ₀ ² =V ² where V is the saturation voltage of the liquid crystal. In other words, by setting the pulse voltage V ₀ to approximately 1.2 times the saturation voltage, the same effective voltage value as when the saturation voltage is constantly applied can be obtained, and in terms of power consumption, response speed, and contrast, the saturation voltage This is the same as when V is constantly applied. Therefore, there is no need for wasted power consumption due to the application of voltages of 2V and 3V as in the past, low power consumption is required, and sufficient response speed and uniform contrast can be obtained.

As mentioned above, if the duty of pulses X, Y, and Z is set to 1/3, the lowest voltage will be required compared to setting a lower duty
In addition, since the response speed is fast, this is most preferable, but it is not limited to this, and it is also possible to drive using a pulse with a smaller duty, for example, a pulse with a duty of 1/4. That is, three systems of pulses having a duty of 1/4 and different phases may be used in place of the pulses X, Y, and Z, and driven in exactly the same manner as described above. However, in this case, the duty of the voltage applied to the liquid crystal that should respond is 2/4, so unless the pulse voltage is set to √2 times the saturation voltage, it will be the same as applying the saturation voltage all the time. The effective voltage value cannot be obtained. Therefore, the pulse duty is most preferably 1/3.

In the above embodiment, polarizing plates A and B having polarizing axes perpendicular to each other are used, but polarizing plates having polarizing axes parallel to each other may also be used. In this case, the brightness and darkness of the display will be different from the above. is reversed.

As detailed above, the present invention provides a liquid crystal display in which a liquid crystal panel in which liquid crystal is interposed between first and second transparent substrates and between second and third transparent substrates is sandwiched between two polarizing plates. By selectively applying pulses with the same waveform and different phases to each electrode of the device, a display area where only one of the two layers of liquid crystal is non-responsive, a display area where only one of the two layers of liquid crystal is non-responsive, a display area where only one of the two layers of liquid crystal is non-responsive, a display area where both are responsive, and a display area where both are non-responsive are created. Since the display state is made to differ between the non-responsive display area, low voltage driving is possible, and integration display can be performed with low power consumption and a thin structure. Therefore, when reading, the scale can be read accurately even when viewed from an oblique direction.

Moreover, since the waveform of each pulse is the same, it is only necessary to supply pulses of a fixed period with a phase shift to each electrode, which simplifies the circuit configuration.

Furthermore, since the application time of the pulses applied within one cycle to the liquid crystals that are to respond is the same, and the voltage applied to the liquid crystals that are to be non-responsive is 0, display can be performed with completely uniform contrast.

In particular, the duty of the above-mentioned constant period pulse should be reduced to 1/
If it is set to 3, the application time within one period of the pulse applied to the liquid crystal to be responded is long, so low voltage driving can be performed and the response speed is fast.

[Brief explanation of the drawing]

FIG. 1 is a front view showing one embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line -- in FIG. 1, and FIG. 3 is a front view showing each of the glass substrates forming the liquid crystal panel in FIG. 4 is an explanatory diagram showing the pulses supplied to each electrode and the resulting pulses applied to the liquid crystal, and FIG. 5 is a block diagram showing an example of a circuit that generates the pulses shown in FIG. 4. Figures 6 and 7
8 are explanatory diagrams for explaining the operation of FIG. 5, FIG. 9 is a sectional view showing an example of a conventional display device, and FIG. 10 is an explanatory diagram for explaining the operation of FIG. 9. It is a diagram. _G1 ...first transparent substrate, _G2 ...second transparent substrate, _G3 ...third transparent substrate, _C0 ...common electrode,
_C1 to _C5 ...First segmented electrode, _C'1 to _C'5 ...Second segmented electrode, _S1 to _S10 ...Third segmented electrode, _LC1 to
LC ₂ ...Liquid crystal, A, B...Polarizing plate.

Claims (1)

[Claims] 1. A common electrode is formed on one surface of a first transparent substrate, a plurality of first divided electrodes are formed on one surface of a second transparent substrate facing the common electrode, and a plurality of first divided electrodes are formed on one surface of a second transparent substrate, A second divided electrode is formed on the other surface of the transparent substrate to correspond to each of the first divided electrodes, and a plurality of third divided electrodes are formed on one surface of the third transparent substrate to face each of the second divided electrodes. A divided electrode is formed between the first transparent substrate and the second transparent substrate, and between the first transparent substrate and the second transparent substrate.
A liquid crystal twisted by 90 degrees is interposed between the transparent substrate and the third transparent substrate, and a polarizing plate is provided opposite to each other surface of the first transparent substrate and the third transparent substrate, and the same A pulse generation circuit is provided that generates three systems of pulses X, Y, and Z that differ only in phase in their waveforms, and one system of pulses X is applied to the common electrode, while the above one system of pulses is applied to the first divided electrode. X and another system of pulses Y are selectively applied, and the above two systems of pulses X, Y are applied to the second divided electrode.
is selectively applied to the third divided electrode, and a pulse Z of another system different from the above one system of pulses X and the above two systems of pulses is selectively applied to the common electrode and the first divided electrode. A region where the same system of pulses is applied to each of the second and third divided electrodes, and a region where a different system of pulses is applied to each of the second and third divided electrodes, and each of the second and third divided electrodes. A region to which pulses of the same system are applied and pulses of other systems are applied to each of the common electrode and the first divided electrode continuously forms a display region in a − display state on the same plane, and the common electrode Pulses of other systems are applied to each of the first divided electrode and the second divided electrode and the third divided electrode.
A region where pulses of different systems are applied to each of the divided electrodes, pulses of the same system are applied to each of the common electrode and the first divided electrode, and each of the second divided electrode and the third divided electrode A method for driving a liquid crystal display device in which regions to which pulses of the same system are applied continuously form display regions in different display states on the same plane.