JPS588512B2 - LCD display method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION When using a liquid crystal display for an electronic desktop calculator, a time-division drive method can be considered from the economic standpoint of reducing the number of drive circuits and connection terminals.

However, when a conventional liquid crystal display is driven by a circuit like the one shown in Figure 1, since the liquid crystal is electrically bidirectional, current flows as shown by the dotted line in Figure 1, which causes crosstalk and selectivity. This had the disadvantage that the segments that were not displayed would be lit in a tingling manner, making it difficult to see the numbers.

In addition, in conventional matrix displays, a voltage that is % or % of the voltage applied to the selected point is applied even to intersections that are not selected, so if this voltage exceeds the threshold voltage of the liquid crystal due to changes in room temperature, etc., it is not selected. There was a drawback that points were also displayed.

Therefore, since the voltage applied to non-selected points must be kept below the threshold voltage, the voltage applied to selected points cannot necessarily be selected to be the saturation voltage, and therefore the contrast is inevitably held below performance. .

In the liquid crystal display method of the present invention, a potential difference corresponding to zero or saturation voltage is applied to both ends of all liquid crystals, and whether or not to display is determined digitally, so the contrast is the maximum value obtained from the characteristics of the liquid crystal. You can choose.

Further, in the liquid crystal display method of the present invention, a potential is applied to all electrodes and no current flows as shown in the circuit of FIG. 1, so crosstalk is prevented.

An object of the present invention is to dramatically improve the quality of display by utilizing the properties of field effect (FE) liquid crystals and devising the structure of the display.

First, a type of FE type, for example, a TN type (twisted nematic) liquid crystal display will be explained.

FIGS. 2 and 3 show typical uses of TN type liquid crystals.

The liquid crystal molecules are oriented as shown in FIG. 2, but this causes scratches on the surface of the glass in that direction, and the liquid crystal molecules are aligned along this direction.

If the directions of rubbing the upper and lower glasses are perpendicular, the liquid crystal molecules in the middle will be twisted little by little, making it possible to achieve the orientation shown in Figure 2.

A liquid crystal layer that is twisted by 90 degrees has optical rotation, and when a voltage is applied to a liquid crystal layer in which the plane of polarization of incident light and passing light rotates by 90 degrees, the molecules align in the direction of the electric field and the optical rotation is lost.
It returns to its original state when the electric field is removed.

In the FE type, this liquid crystal layer is used by sandwiching it between two polarizing plates whose polarization axes are orthogonal to each other, as shown in the third figure.

When the liquid crystal has an optical rotation of 90°, light passes through it, but the area to which voltage is applied has no optical rotation, so the light is blocked and the figure is displayed in darkness. Switching of passing and blocking of incident light is performed by turning on and off.

This is the principle of the FE type.

Next, specific examples of the present invention will be explained.

Example 1 FIG. 4 shows the structure of an embodiment of the display according to the present invention.

A TN type liquid crystal is filled between the two glass plates G1 and G02.

The symbols ■ and ■ indicate the rubbing direction and the polarization direction, → indicates parallel to the paper surface, and ■ indicates the direction perpendicular to the paper surface.

A voltage as shown in FIG. 5 is applied to each of the three layers of electrodes N1, N2, and N3.

The voltage when the switch is selected is supplied to the upper terminal of each switch, and the voltage when the switch is not selected is supplied to the lower terminal.

In FIG. 5, segment A is selected and segment B is selected. This shows the case where C and D are not selected.

When the display device is driven in a time-division manner, it is classified into these four cases.

When a voltage is applied as shown in Fig. 5 and E/2 is selected to be higher than the saturation voltage, the liquid crystal molecules between each electrode are as shown in Fig. 6. Since both are aligned in the direction of the applied voltage, the light travels without optical rotation.

In segments B, C, and D, liquid crystal molecules are aligned in the direction of the electric field only in one of the upper and lower liquid crystals, and in the other one, light is rotated by 90°.

Also, light passes through areas other than the segments.

In this way, the contrast of the display can be improved.

Furthermore, considering the lifespan of the liquid crystal, it is preferable to drive it with alternating current; however, this purpose can be achieved by changing E and 0 to 0 and E, respectively, in FIG. 5.

Furthermore, if the directions of the polarizing plates are parallel in FIG. 6, light will pass only in the case of segment A, so that a transmission type display can also be constructed.

Embodiment 2 It is clear that the same effect as the display shown in FIG. 4 can be expected with the four-layer structure shown in FIG. 7.

Example 3 When a voltage is applied as shown in Fig. 9 in a display having a structure as shown in Fig. 8 in which the electrode N4 in Fig. 7 is used as a single common electrode,
Liquid crystal molecules are lined up as shown in Figure 10.

In segment A, the light rotates by 90 degrees only in the upper liquid crystal, and in segment B, the light rotates by 90 degrees in both the upper and lower liquid crystals, so the direction of the light returns to its original direction.

In segments C and D, the upper and lower liquid crystals are both aligned in the direction of the electric field, so light passes through them as is.

In areas other than the segment, the direction of the light returns to the original direction as in the case of segment B.

Therefore, if the polarization direction of the polarizing plate is made parallel, segment A
Only in the case where no light passes through, segment A is displayed.

To apply alternating current to the liquid crystal, E and 0 may be set to 0 and E, respectively.

It is also clear that the same effect can be expected with a structure as shown in FIG.

Embodiment 4 A matrix type display as shown in FIG. 12 can be considered from the segment type display having the structure shown in FIG.

FIG. 13 is a plan view thereof, in which the electrode Y1
, Y2 are applied with E and E/2 when selected and not selected, respectively, 0 and E are applied to the electrodes X1 and X2 when selected and not selected, respectively, and E is always applied to the electrode Z.

The voltages applied to the intersections A, B, C, and D are as follows.

Therefore, as in the case of the first embodiment, only segment A is displayed.

It is clear that the structure shown in FIG. 14 can also be displayed in the same way.

In any of the embodiments described above, there is no need to drive in consideration of the threshold voltage at each intersection, so the voltage movable range is widened.

Since the electrode spacing may vary widely, the display device can be manufactured easily.

Since it can be driven in a saturated state, it has the advantage of providing clear display.

Example 5 The structure shown in Fig. 15 is one in which a polarizing plate is further provided between the substrates separating the two-layer liquid crystal cells in Fig. 8, and when a voltage is applied as shown in Fig. 16, the structure shown in Fig. 17 is Liquid crystal molecules are arranged like this.

The portion to which the voltage is applied loses its optical rotation, and the light passes through the polarizing plate whose polarization direction is all set in the same direction, and segment A is in this state.

If no voltage is applied to one digit or segment, the polarization direction will be rotated by 90 degrees due to the liquid crystal, and no light will be transmitted through that portion.

Therefore, it is bright only when the digits and segments are ON-ON, and O
N-OFF or OFF-ON, and when OFF it becomes dark.

In other words, digit selection and segment selection are performed electrically independently,
In the OFF state, the voltage can be set to O, only one power supply is required, and any voltage higher than the threshold value can be applied.

In addition, in the display method of the present invention, only the selected point is bright and does not appear bright except at the angle where the bright field can be seen, and a clear display without causing false display can be obtained.Furthermore, the shape of the electrode is simple, especially in the digit part. Since only a bright and dark filter is applied in a range that encompasses the entire digit part to be displayed, precision in shape is not required.

Furthermore, it is easy to form a matrix display by using the electrodes corresponding to the digits as the X electrodes and the electrodes corresponding to the segments as the Y electrodes, and intersecting the grid electrodes at right angles to each other.

If this structure is used, the ON-OFF signals are E and 0, and there is no crosstalk, so E can be made sufficiently large and high-speed response can be achieved, especially for multi-digit displays and matrix displays. Are suitable.

Also, since only the display portion is transparent, it is suitable for transmission type display or projection type display.

Furthermore, it has many advantages such as simple structure and easy manufacture.

[Brief explanation of the drawing]

Figure 1 shows how crosstalk occurs in a liquid crystal display, Figure 2 shows how the molecules of TN liquid crystal are aligned, and Figure 3 shows how crosstalk occurs when the voltage is turned on and off. A diagram showing how liquid crystal molecules are arranged and switching of passing and blocking incident light. FIG. 4 is a cross-sectional view of Example 1 of the display used in the present invention and a diagram showing the electrical connection/separation relationship between electrodes. , Fig. 5 is a diagram showing the voltage applied to each electrode of the display device in Fig. 4 and the potential relationship, and Fig. 6 is a diagram showing the liquid crystal molecules between each electrode when voltage is applied as shown in Fig. 5. 7 is a diagram showing the display device of Example 2, FIG. 8 is a diagram showing the display device of Example 3, and FIG. 9 is a diagram showing the arrangement of the display device in FIG. 8. Figure 10 is a diagram showing the arrangement of liquid crystal molecules between each electrode when a voltage is applied as shown in Figure 9, and Figure 11 is expected to have the same effect as Example 3. FIG. 12 is a diagram showing the display device of Example 4 with a matrix structure. FIG. 13 is a diagram showing the voltage applied to each electrode of the display device in FIG. 12. FIG. Figure 12 is a diagram showing a display that can be expected to have the same effect as that of Figure 12, Figure 15 is a diagram showing a display of Example 5,
Figure 6 is a diagram showing the voltage applied to each electrode of the display device in Figure 15, and Figure 17 is a diagram showing how liquid crystal molecules are arranged between each electrode when voltage is applied as in Figure 16. be. G1, G2, G3 are glass, N1pN2, N3, N4,
X, Y, and Z are transparent electrodes, and L1 and L2 are polarizing plates.

Claims (1)

[Claims] 1. In a liquid crystal display device comprising polarizing plates on both sides of a liquid crystal cell in which a field effect liquid crystal is interposed between a first transparent member having a first electrode and a second transparent member having a second electrode. , at least one transparent member having a first electrode and a second transparent member having a second electrode facing each other with the liquid crystal interposed therebetween.
A third transparent member having two third electrodes is provided, and the liquid crystal existing between the first electrode, the third electrode, and the second electrode in a desired portion is in a state where light passes through, and In other cases, a voltage is applied to make one of the liquid crystals present between the electrodes in a state where light is blocked, or the light passing and blocking states of the liquid crystal in the desired portion and other portions other than the desired portion are reversed. A liquid crystal display method characterized by applying a voltage that makes