JPH04178632A - Liquid crystal display element and driving method thereof - Google Patents

Abstract

PURPOSE:To obtain the display of high utilization efficiency of light without requiring polarizing plates by combining a 1st liquid crystal display element formed by forming light shielding films larger than a light condensing diameter on the outer side of the glass substrates of a liquid crystal cell having the light condensing effect of the liquid crystal inserted between two sheets of the glass substrates with transparent electrodes subjected to an orientation treatment in the same direction and a 2nd element having the same structure as the structure of this element in such a manner that the orientation directions of the liquid crystals intersect orthogonally with each other and impressing the same driving voltage thereto. CONSTITUTION:The light shielding films 104 are formed on the outer side of the glass substrates of the liquid crystal which is formed by combining two sheets of the liquid crystal display elements 105, 106 having the same structure in such a manner as to intersect the orientation directions of the liquid crystals orthogonally with each other, and the respective elements of which have the light condensing effect of the liquid crystal 103 inserted between two sheets of the glass substrates 102, 107 with the transparent electrodes. The same voltage is impressed to this liquid crystal cell from a driving source. The element A 105 on the incident light side shuts off the components parallel with the liquid crystal orientation and allows the straight pass-through of the components perpendicular thereto when the proper voltage above the threshold voltage of the liquid crystal is impressed to the cell. The element 106 on which the light is made incident next shuts off this light and a dark display is obtd. On the other hand, the most of the incident light is transmitted and a bright display is obtd. in the case of the voltage below the threshold voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display element used in displays and the like and a method for driving the same.

[Conventional technology]

Currently, the most commonly used display method for liquid crystal display devices is one that utilizes the twisted nematic effect. First, the liquid crystal display element used in this will be explained. Two glass substrates with transparent electrodes that have been subjected to alignment treatment such as rubbing are pasted together so that the rubbing directions are perpendicular to each other, and a nematic liquid crystal is sandwiched between them.

In liquid crystal, the long axis of the molecules is parallel to the substrate, and the distance between the two substrates is 9.
It has a twisted orientation of 0 degrees. Polarizing plates are attached to both surfaces of this substrate so that the polarization directions are parallel or perpendicular to each other to form a liquid crystal display element.

Next, the display principle will be explained. It is assumed that the polarization directions of the two polarizing plates on both sides of the substrate are parallel to each other. When no voltage is applied to the liquid crystal, linearly polarized light incident on the liquid crystal display element is rotated by 90 degrees along the twist of the liquid crystal molecules. Since the polarization directions of the polarizing plates pasted together are parallel to each other, the rotated light cannot pass through the polarizing plates, resulting in a dark state.

When a voltage is applied to the liquid crystal, the liquid crystal molecules stand up perpendicular to the substrate, the molecules are untwisted, and the incident light maintains its original polarization state. Therefore, as explained above, the light passes through the polarizing plate and becomes a bright state.As explained above, a bright and dark display is possible depending on the voltage applied to the liquid crystal.

[Problem to be solved by the invention]

A liquid crystal display element utilizing this twisted nematic effect requires a polarizing plate as described above. Therefore, in this liquid crystal display device, more than half of the incident light, which is normally undefined polarized light, is lost by the polarizing plate. This not only reduces the light utilization efficiency, but also causes the temperature of the liquid crystal display element to rise because the lost light is absorbed by polarizing plates, etc., and is a contributing factor to the deterioration of the liquid crystal.

Is it possible to consider a method in which the undefined polarized incident light is divided into two mutually orthogonal polarization components, that is, p-polarized light and S-polarized light, each of which is displayed using a panel with the same characteristics, and the two images are combined? In this case a polarizing beam splitter
It is not practical because it requires optical elements such as and space for them.

An object of the present invention is to provide a liquid crystal display element that solves the problems of the prior art described above, and a driving method using the same to obtain a display with high light utilization efficiency.

[Means to solve the problem]

The liquid crystal display element of the present invention has two
A first liquid crystal display element in which a light shielding film larger than a light collecting diameter is formed on the outside of a glass substrate of a liquid crystal cell having a light collecting function in which a liquid crystal is sandwiched between two glass substrates with transparent electrodes; It is characterized in that a second liquid crystal display element having the same structure as the display element is combined so that the orientation directions of the liquid crystals are orthogonal to each other.

In addition, the method of driving a liquid crystal display element is to use a liquid crystal cell that has a light-concentrating effect, in which a liquid crystal is sandwiched between two glass substrates with transparent electrodes that have been subjected to an alignment process in the same direction. In a liquid crystal display element in which a first liquid crystal display element on which a large light-shielding film is formed and a second liquid crystal display element having the same structure as the first liquid crystal display element are combined so that the alignment directions of the liquid crystals are orthogonal to each other. , the same driving voltage is applied to the first liquid crystal display element and the second liquid crystal display element.

[Effect]

The liquid crystal display element of the present invention has two
A liquid crystal cell has a light-concentrating effect, in which a liquid crystal is sandwiched between two glass substrates with transparent electrodes. Two liquid crystal display elements with the same structure, in which a light shielding film is formed on the outside of the glass substrates, are arranged so that the liquid crystal orientation directions are perpendicular to each other. It is a combination. The position of each light shielding film corresponds approximately to the focal point when the light condensing action occurs, and the size of the light shielding film is slightly larger than the light collecting diameter.

The driving method of the present invention applies the same driving voltage to two liquid crystal display elements. When the incident light is made parallel to the glass substrate and a suitable driving voltage higher than the threshold voltage of the liquid crystal is applied, the component parallel to the liquid crystal orientation of the liquid crystal display element on the incident light side, that is, the extraordinary light, has a condensing effect. Since a light-shielding film is formed at the 7 focal point position 1, which receives the light and converges on the focal position,
This abnormal light is blocked and does not exit to the other side.

The component perpendicular to the liquid crystal alignment of the liquid crystal display element, that is, the ordinary light, is not subjected to the light condensing action, so it is extracted as is. However, the next liquid crystal display element is assembled so that the alignment direction of the liquid crystal molecules is orthogonal to the previous liquid crystal display element. Therefore, it becomes a component parallel to the liquid crystal alignment, that is, extraordinary light, which is subjected to a condensing action and converged at the focal position.

Since a light shielding film is formed at the focal point position as in the previous liquid crystal display element, the light is blocked. In this way, by combining two liquid crystal display elements having the same structure so that the orientation directions of the liquid crystals are perpendicular to each other, all incident light is blocked. In other words, a dark display is obtained. On the other hand, even if an extremely low driving voltage below the threshold voltage of the liquid crystal is applied, no special effect occurs on either extraordinary light or ordinary light. Therefore, most of the incident light travels straight and is transmitted. In other words, a bright display can be obtained. At this time, the light-shielding film portion is shielded from light, but since the light-shielding film is extremely small compared to the display area, the light loss is negligible.

As described above, the liquid crystal display element of the present invention does not require a polarizing plate, and the driving method thereof enables display with high light utilization efficiency.

〔Example〕

Next, examples of the present invention will be described. Figure 1 (a>,
, (b), and (c) show an example of the structure of a liquid crystal display element. (a) is a side view, (b).

(c) is a front view. Two liquid crystal display elements 105 and 106 having the same structure are combined so that the orientation directions of the liquid crystals are orthogonal to each other. Each liquid crystal display element consists of two glass substrates 102 and 107 with transparent electrodes.
04 is formed on the outside of a glass substrate of a liquid crystal cell having a light condensing function sandwiching 03. The position of the light-shielding film corresponds to the focal point of the lens when it operates as a lens. Further, the size of the light shielding film is slightly larger than the condensing diameter. A liquid crystal cell with a light-concentrating effect is generally called a liquid crystal lens, and there are various structures, but here we will use a structure in which a liquid crystal is sandwiched between a pixel electrode having a circular window-like pattern and a flat transparent electrode.

Before explaining the method for driving a liquid crystal display element of the present invention, the principle of operation of a liquid crystal lens will be explained using FIG. 3. The liquid crystal lens in this case has a structure in which a liquid crystal 103 is sandwiched between a pixel electrode 301 having a circular window-like pattern and a flat transparent electrode 302. When only a voltage lower than the threshold voltage of the liquid crystal is applied between the electrodes, the liquid crystal 103 is in a homogeneous alignment, that is, the long axis of the liquid crystal molecules is parallel to the substrate, as shown in FIG. In other words, since the focal length of the liquid crystal display element is infinite, neither the ordinary light nor the extraordinary light of the incident light is converged, and some light is extracted.Here, the extraordinary light refers to a polarized light component parallel to the alignment direction of liquid crystal molecules, and ordinary light refers to a polarized light component perpendicular to the alignment direction of liquid crystal molecules.

When a suitable voltage higher than the threshold voltage of the liquid crystal is applied between the electrodes, as shown in Figure 3(b), the center of the pattern where the electric field strength is small remains aligned parallel to the substrate with its initial orientation, and the electric field strength decreases. At the large pattern ends, the long axes of liquid crystal molecules are aligned perpendicular to the substrate. As the long axes of liquid crystal molecules are oriented perpendicular to the substrate, the effective refractive index for extraordinary light becomes smaller, so the refractive index distribution becomes smaller from the center of the pattern toward the periphery. Therefore, it has a condensing characteristic, that is, a convex lens effect, for the extraordinary light component of the incident light. At this time, no effective refractive index distribution is produced for ordinary light, so it has no effect. In other words, ordinary light is not focused but extracted (
, 9 comes out like this, 8! 11. When applying the second voltage, the threshold voltage is the threshold voltage device. It has a lens effect against ordinary light, but it does not have a lens effect against ordinary light. Furthermore, when a voltage below the threshold voltage is applied, it does not have a lens effect for either extraordinary light or ordinary light.

Next, the display principle according to the method for driving a liquid crystal display element of the present invention will be explained using FIG. 2. 2 LCD display elements 1
The same voltage is applied to 05 and 106 from the drive power supply 203. Note that the incident light is parallel to the glass substrate. Figure 2 (a) shows the case where an appropriate voltage higher than the threshold voltage of the liquid crystal is applied. 201 receives the light condensing action according to the principle described above and converges at the focal position.The light shielding film 1 is placed at the focal position.
Since 04 is not formed, this abnormal light is blocked and does not exit to the opposite side. The component perpendicular to the liquid crystal orientation of the liquid crystal display element 105, that is, the ordinary light, is not subjected to the light condensing action as described above, and therefore is extracted as is. however,
The next liquid crystal display element 106 is the previous liquid crystal display element]
6 is combined so that the orientation direction of the liquid crystal molecules is perpendicular to 05, so it becomes an extraordinary light 202 for the liquid crystal display element B, receives a condensing action, and converges at the focal position 6
Since a light shielding film 104 is formed at the focal point position, similar to the liquid crystal display element, the light is blocked. In this way, by combining two liquid crystal display elements having the same structure in which the orientation directions of the liquid crystals are orthogonal to each other, all incident light is blocked. That is,
A dark display is obtained.

On the other hand, FIG. 2(b) shows the case where a voltage lower than the threshold voltage of the liquid crystal is applied. At this time, two liquid crystal display elements 105,
106 has no special effect on either extraordinary light or ordinary light. Therefore, most of the incident light travels straight and is transmitted. In other words, a bright display can be obtained. At this time, cut off! 10
Although the portion 4 is shielded from light, the light shielding film 104 is extremely small compared to the display area. Since the condensing diameter of the liquid crystal lens is about 10 microns in diameter, if the display area is assumed to be 100 to 200 square, which is one pixel of a normal liquid crystal panel, the area of the light shielding film 104 is less than 1% of the pixel area. be. Therefore, optical loss is also negligible.

In this way, the liquid crystal display element of the present invention does not require a polarizing plate, and enables display with high light utilization efficiency.

〔Effect of the invention〕

As described above, the liquid crystal display element and driving method of the present invention enables display with high light utilization efficiency without the need for polarizing plates, and is very useful industrially.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an example of the n4 structure of the liquid crystal display element of the present invention, Fig. 2 is a diagram showing an example of the display principle by the driving method of the liquid crystal display element of the present invention, and Fig. 3 is a diagram showing the principle of operation of the liquid crystal lens. FIG. 1,,01...Transparent electrode, 102.107...Glass substrate, 103...Liquid crystal, 104...Light shielding film, 105
...Liquid crystal display element A, 106...Liquid crystal display element B,
201... Abnormal light for liquid crystal display element A, 202...
... Abnormal light for liquid crystal display element B, 203 ... Drive power supply, 301 ... Circular window-shaped electrode, 302 ... Flat plate transparent electrode. Dairuiri Bentographer Atsushi Uchi Sound Diagram 1 @ Diagram 2

Claims (2)

[Claims] (1) A liquid crystal cell with a light-concentrating effect in which a liquid crystal is sandwiched between two glass substrates with transparent electrodes that have been subjected to alignment treatment in the same direction, and a light-shielding film larger than the light-condensing diameter formed on the outside of the glass substrates. 1. A liquid crystal display element, characterized in that a first liquid crystal display element and a second liquid crystal display element having the same structure as the first liquid crystal display element are combined so that the alignment directions of the liquid crystals are orthogonal to each other. (2) A liquid crystal cell with a light-concentrating effect, in which a liquid crystal is sandwiched between two glass substrates with transparent electrodes that have been subjected to alignment treatment in the same direction, has a light-shielding film larger than the light-condensing diameter formed on the outside of the glass substrate. In a liquid crystal display element in which a first liquid crystal display element and a second liquid crystal display element having the same structure as the first liquid crystal display element are combined so that the orientation directions of the liquid crystals are orthogonal to each other,
A method for driving a liquid crystal display element, comprising applying the same driving voltage to the first liquid crystal display element and the second liquid crystal display element.