JPS62262022A - Device utilizing electro-optical effect - Google Patents

Abstract

PURPOSE:To obtain plural kinds of different electro-optical characteristics in a display surface formed by a pair of conductive films, by inserting and holding a material having an electro-optical effect, and forming a dielectric film having plural parts with different thicknesses, between said material and the conductive film. CONSTITUTION:A material 7 having an electro-optical effect is inserted and held between a pair of conductive films 2a, 2d, a dielectric film 6 having plural parts of each different thickness is formed between said material and the conductive film, a suitable driving voltage is impressed between a pair of conductive films, intensity of an electric field impressed to each part of said material, corresponding to plural parts of each different thickness is made different, and an electro-optical characteristic corresponding to each part of this material is obtained. That is to say, the intensity of the electric field impressed to each part of the material having the electro-optical effect, corresponding to plural parts of each different thickness becomes different. Accordingly, in a display surface by a pair of conductive films, an electro-optical characteristic corresponding to each part of the material is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to display devices such as liquid crystal, EL, and LED, and devices that utilize electro-optic effects such as optical shutters and sensors.

(Prior Art) A conventional liquid crystal device has a glass substrate 1 as shown in FIG.
A substrate was used which was coated with transparent conductive films 2a, 2b+2c, an insulating film 3 made of silicon oxide or the like, an alignment film S for aligning the liquid crystal 4, and wrapped.

(Problems to be Solved by the Invention) In the above device, when a constant voltage amplitude is applied between a pair of parallel transparent conductive films, the transmittance distribution within the display surface between the pair of transparent conductive films is basically It remained constant and did not vary.

An object of the present invention is to provide electro-optical properties (
For example, it is an object of the present invention to provide a device that can have multiple types of transmittance.

(Means for Solving the Problems) A device using the electro-optic effect of the present invention includes a material having an electro-optic effect sandwiched between a pair of conductive films, and a material having a different thickness between the material and the conductive film. A dielectric film having a plurality of parts is formed, and an appropriate driving voltage is applied between the pair of conductive films to create an electric field applied to each part of the material corresponding to the plurality of parts with different thicknesses. By varying the strength, electro-optical properties can be obtained depending on each part of the material.

Further, the material having an electro-optic effect is a ferroelectric liquid crystal, and the effective display area of one pixel in active matrix driving is a pair of conductive films.

(Function) According to the present invention, the strength of the electric field applied to each part of the material having an electro-optic effect becomes different, corresponding to a plurality of parts having different thicknesses. Therefore, electro-optical characteristics depending on each part of the material can be obtained within the display surface formed by the pair of conductive films.

(Example) An example of the present invention will be described based on FIGS. 1 to 4.

In this figure, the same parts as those in the conventional example shown in FIG. 5 are designated by the same reference numerals, and the explanation thereof will be omitted.

FIG. 1(a) shows an embodiment in which the present invention is applied to a display device using a material having an electro-optic effect. In the figure, in order to change the strength of the electric field that is effectively applied to the material that has an electro-optic effect between a pair of conductive films,
A 1'R body film 6 is used, and the thickness of the dielectric film 6 is varied.

When a material having an electro-optic effect (for example, ferroelectric liquid crystal) is used in FIG. 1(b), the transmittance corresponding to the portion ABC in FIG. 1(a) and the distance between the pair of transparent conductive films 2a and 2d It shows the relationship with the voltage applied to (or drive conditions such as voltage x pulse time). For materials that exhibit such electro-optical properties.

In the conventional structure shown in FIG. 5, the transmittance could only be selected from 0% or 100% depending on the voltage applied to the pair of conductive films. However, in this embodiment, when the applied voltage is V, V<V.

Four types of transmittances having different areas can be displayed by applying voltages in the range of VA<V<V, Vn<V<Vc+ va<v.

Generally, the thickness Dl of the dielectric film 6 is N between a pair of conductive films.
The minimum voltage that makes the i-th thick part 100% transmittance is V.

And the area of the i-th thickness part is S.

Then, the TI shown in FIG. 1(c) becomes as follows.

Σ ReTI=−Σ SJ Therefore, in the case of a display device or an optical shutter, it is sufficient to determine V and T that match the design concept and SL.

Here, as an example of a method for effectively applying a plurality of voltages or electric field strengths to a material having an electro-optic effect between a pair of conductive films to which a constant voltage is applied, the following method is used. I can think of things.

As shown in FIG. 1(d), the dielectric film 6 can be formed by changing the thickness of the dielectric film 6 on both of the pair of conductive films.

As shown in FIG. 1(e), by continuously changing the thickness of the dielectric 16, the strength of the voltage or electric field effectively applied to the material 7 having an electro-optic effect is continuously changed. can be done.

As shown in FIG. 1(f), multiple types of dielectric films 6°8.
It can also be created by overlapping 9.

In addition, when the thickness of the dielectric film is changed, the difference in level may be eliminated by using water glass or an alignment film 5, or as shown in FIG. 1(g), the thickness of the first dielectric film 6 may be A second dielectric film 8 having a dielectric constant different from that of the first dielectric film 6 is deposited, and then the surface of the second dielectric film 8 is optically polished. A flat surface can be obtained by using the body membrane 8, and a material 7 having an electro-optic effect can be obtained.
19 becomes constant.

As can be seen from the above considerations, the structure of the device of the present invention can be effectively applied to a sensor that can directly convert the voltage between a pair of conductive films into a display mode. Furthermore, if the response speed of a material with an electro-optic effect differs depending on its thickness,
It can also be used as a sensor for driving frequency, etc.

FIG. 2(a) shows an embodiment in which the present invention is applied to a liquid crystal panel. Here, in order to change the strength of the voltage or electric field that is effectively applied to the material (liquid crystal 4) having an electro-optical effect between the pair of conductive films 2a and 2d that constitute the display picture element, a dielectric material is used. The thickness of the film 8 is changed into three types. Note that, although a negative display TN liquid crystal panel equipped with the polarizing plate 10 will be explained here as an example, the same applies to a positive display panel or one using GH liquid crystal.

Figure 2(b) shows that when a certain liquid crystal is used with an appropriate thickness,
Transmittance corresponding to parts A, B, and C in FIG. 2(a),
It shows the relationship with the voltage applied by static driving between the pair of transparent conductive films 2a and 2d.

For example, if we consider the transmittance when a voltage of 3 volts is applied, the transmittance is about 90% in the A part and about 2 in the B part.
2%, about 2% in the C part, and the pair of transparent conductive films 2
Even when a constant voltage is applied between a and 2d, parts exhibiting different transmittances can be created. Furthermore, the second
FIG. 2(c) shows the optical characteristics of the entire pair of transparent conductive films when the areas showing the optical characteristics of portions A, B, and C shown in FIG. 2(b) are equal. When changing the transmittance from 10% to 90% as shown here, the applied voltage is changed to 2.
．． The conventional one shown in Fig. 5 can be varied over a wide voltage range from 2 volts to 4.5 volts.

If the optical characteristics were to be composed only of the optical characteristics shown by A in FIG. In this case, an applied voltage width that is more than double that can be obtained. Moreover, compared to the conventional one, 2.
It has the advantage of being able to be used at a voltage as low as 2 volts.

FIGS. 3(a) and 3(d) show examples of liquid crystal panels in which color filters are used as dielectric films 9-a, 9-b, and 9-c.

FIG. 3(b) shows almost the same value λ from dielectric film 9-c to dielectric film 9-a. It is a filter that widens the bandwidth while having a peak of .

FIG. 3(c) shows a filter in which the respective peak values shift toward longer wavelengths from the dielectric film 9-c to the dielectric film 9-a.

FIGS. 3(b), (c), and (e) show the spectral characteristics of various filters.

By combining FIGS. 3(a) and 3(b), the voltage dependence of color purity within a pair of conductive films can be obtained.

Further, the combination of FIGS. 3(a) and 3(c), the combination of FIG. 3(d) and 3(e), etc., taking into consideration the optimum liquid crystal gap due to the step difference of the color filter as a dielectric film, can be considered. In FIG. 3(d), the three types of dielectric films are
When the three primary colors are assigned, the result is as follows.

Let the dielectric constant and thickness of each dielectric film 9 at 1 (Q=a-c) be ε,,D, and red for i=a.

Assign green to 1==b and blue to i=c.

In the case of ε1D, ε1Dゎ〈εe De, as the voltage between the pair of conductive films increases, it changes from red → yellow → white, and similarly, in the case of εb D b < E e De < εa D s, Green → cyan → white 1-, εcDc
In the case of ε1D, <ε, Db, the color becomes blue → magenta → white. Furthermore, if the optimal liquid crystal gap is considered and fixed as D<Dh<DC, and only E is changed and designed to satisfy the above inequality, a new display can be created.

So far, we have described a pair of conductive films, which are considered to correspond to one pixel, especially in active matrix driving, and there are no new problems in the driving method, and they are particularly effective for halftone display.

Static drive is also effective when displaying halftones, and if the embodiment shown in Fig. 3 is adopted, 1
Multicolor display within a pixel is also possible. In addition, dielectric films include insulating films and organic materials.

A variety of dielectrics can be used, including inorganic filters and the like.

FIG. 4(a) shows a panel using a dot matrix type dynamic driving method.

FIG. 4(b) and FIG. 4(C) are respectively shown in FIG. 4(a).
) shows the vicinity of the lower substrate in the AB cross section and the vicinity of the upper substrate in the B-C cross section. In this case, a "pair of conductive films" is treated as corresponding to one pixel, here 4
Different types of dielectric films 11 are used, and by determining the dielectric constant and thickness of each, it is possible to combine parts with two types of optical characteristics per pixel. Furthermore, by determining the area occupied by each type, the relationship between the voltage between a pair of conductive films and the transmittance can be obtained.

The intermediate color display using the present invention additionally utilizes area gradation, and the arrangement of areas occupied by each intermediate color within one pixel can also be devised. For example, to display one trio of RGB colors, the center of the color may be bright as shown in Figure 4(d), or the center of the trio of colors must be bright as shown in Figure 4(e). You can do it. However, regarding the driving method, it is necessary to fully consider crosstalk in this case.

(Effects of the Invention) According to the present invention, within the display surface between a pair of conductive films,
It becomes possible to exhibit a plurality of different electro-optical characteristics, and has excellent effects on halftone display using ferroelectric liquid crystals and the like.

[Brief explanation of drawings]

Figure 1 (aL (dL (e), (f), and (g) are cross-sectional views of a liquid crystal panel in an embodiment of the present invention;
b), (Q) are relationship diagrams between applied voltage and transmittance of the liquid crystal panel, FIG. 2(a) is a cross-sectional view of the liquid crystal panel of the second embodiment of the present invention, and FIG. ) is a diagram showing the relationship between applied voltage and transmittance of the same liquid crystal panel, FIG. 3(a). (d) is a cross-sectional view of a liquid crystal panel according to a third embodiment of the present invention, FIGS. 3(b), (c), and (e) are spectral characteristic diagrams of the same filter, and FIG. Schematic plan views of other liquid crystal panels used, FIGS. 4(b) and 4(c) are A-B and B of the same (a).
-C is a partial sectional view, FIGS. 4(d) and 4(e) are diagrams showing a method of arranging brightness and darkness within an RGB trio, and FIG. 5 is a sectional view of a conventional liquid crystal panel. 1...Glass substrate, 2a, 2b, 2
c, 2d - transparent conductive film, 3... silicon oxide, 4... liquid crystal, 5... alignment film, 6,8
,9,11...Dielectric film, 7...Material, 1o.
··Polarizer. Patent applicant Matsushita Electric Industrial Co., Ltd. Figure 1 (a) Figure 1 (b) Oku ■ < VB < VC Figure 1 (c) Figure 1 (d) Figure 1 (e) Figure 1 (f ) Figure 1 Figure 2 (a) )! 1 BC 10-Yang I'i5'l Dragon Figure 2 (b) A B
CFigure 2 (C) ('/,) Hill T)jD Den L 9-a9-b9-c---AfJ, I Honzuki Figure 3 (b) Figure 3 (c) Figure 3 ( d) 9-a9-b9-c--aftt slope Fig. 3 (e) Fig. 4 (a) Y+ Y2 Y3Y4 ... Fig. 4 (b) (c) a Fig. 4 (d) GB (e) G Figure 5

Claims (3)

[Claims] (1) A material having an electro-optic effect is sandwiched between a pair of conductive films, a dielectric film having a plurality of parts with different thicknesses is formed between the material and the conductive film, and Applying an appropriate driving voltage to vary the strength of the electric field applied to each part of the material corresponding to the plurality of parts having different thicknesses, thereby obtaining electro-optic characteristics corresponding to each part of the material. A device that utilizes electro-optical effects. (2) A device utilizing an electro-optic effect according to claim (1), wherein the material having an electro-optic effect is a ferroelectric liquid crystal. (3) A device utilizing an electro-optic effect according to claim (1), wherein the effective display area of one pixel in active matrix driving is formed by a pair of conductive films.