JPS6245521B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal polarizer used in liquid crystal color changing devices, liquid crystal display devices, and the like.

The liquid crystal polarizer of the present invention is a linear polarizer that utilizes the dichroism of a dichroic liquid crystal compound or a dichroic dye, and can be used, for example, in a twisted nematic type liquid crystal color changing device or a liquid crystal display device. The polarizer used in such devices is usually a polymer film containing oriented dichroic dye. The present invention provides a novel polarizer using a dichroic molecule orientation method that is completely different from such conventional polarizers.

The polarizer of the present invention consists of a sheet of plastic material having a large number of open elongated pores aligned in a single direction and carrying a liquid crystal material, said liquid crystal material being dichroic or carrying a dichroic dye. The pores are characterized in that they have a size slightly larger than the size of liquid crystal molecules so that the liquid crystal material can be held as a highly oriented layer.

It is well known that liquid crystal molecules can become oriented by interaction with the walls of the container in which they are housed.

In the present invention, when a liquid crystal substance is introduced into the elongated pores existing in the plastic material sheet constituting the polarizer of the present invention, the introduced liquid crystal molecules are moved in the longitudinal direction of the pores by the action of the inner surface of the pores. The finding that if held in an oriented state and the pores aligned such that the longitudinal direction of the pores on the sheet point in a single direction, the entire sheet can essentially function as an oriented liquid crystal layer. It is based on

It is also known that the orientation direction of liquid crystal molecules can be controlled by applying appropriate treatments to the inner surface of the liquid crystal storage container. For example, the surface of the plate supporting the liquid crystal layer may be rubbed in a single direction or chemical substances A liquid crystal layer oriented in a desired direction is obtained by vapor deposition. In contrast, the pores in the present invention do not have any particular surface treatment on their inner surfaces, but simply by introducing liquid crystal molecules into the pores, the liquid crystal molecules are maintained in an oriented state due to the shape of the pores. be.

That is, the liquid crystal introduced into the pores provided in the sheet is held in the shape of an elongated rectangular parallelepiped, and is oriented in the longitudinal direction by being predominantly subjected to surface action or interfacial action in the longitudinal direction.

Therefore, the width of the pores of the present invention must be such that the action of both surfaces extends to the center of the liquid crystal material, and a width of about 10-odd microns or less, which is used in ordinary liquid crystal cells, is sufficient. Yes, preferably several microns. The same thing can be said about the thickness of the sheet, but since the orientation of liquid crystal molecules is obtained from both the action of the pore sides and the action of the interface,
It has been found that the thickness of the sheet is not so critical as long as the width of the pores is sufficiently narrow, and that it can be used up to several tens of microns, which is greater than the thickness of the above-mentioned ordinary liquid crystal cell.

The length of the pores should be sufficiently long compared to the width so that the liquid crystal molecules are aligned, and may be 100 microns or more relative to the width of the pores as described above.

In the present invention, the definition of the pore size as "slightly larger than the liquid crystal molecules" refers to the size of the pores that can hold the liquid crystal molecules introduced into the pores in a substantially oriented state by the action described above. It indicates the size and shape of the hole. The size and shape of this pore also depends on the type of liquid crystal material introduced.

The liquid crystal material is introduced into the pores by coating, printing or spraying on one or both sides of a sheet of plastic material containing the pores. The liquid crystal material applied to the surface of the sheet is filled into the open pores by capillary action. Thereafter, by wiping off the excess liquid crystal material, the liquid crystal material within the pores will remain intact and the surface of the plastic material sheet will have a dry feel.

The liquid crystal material can fill any range of pores on the sheet of plastic material. The pores in the portion of the sheet not filled with liquid crystal material may be filled with a non-liquid crystal organic liquid, such as lubricating oil.

The dichroism necessary for a linear polarizer can be obtained either by the liquid crystal molecules themselves being dichroic or by mixing a dichroic dye with the liquid crystal material. The dichroic dye mixed in the liquid crystal material is oriented in the oriented liquid crystal molecules due to the so-called guest-host effect.

The invention will be further described with reference to the accompanying drawings.

A sheet 1 of polypropylene, such as CELGARD 2400, whose thickness is typically on the order of 25 microns, shown in FIG. 1, has a large number of open elongated pores 2. This pore 2
are all aligned in a single direction and have dimensions slightly larger than the liquid crystal molecules so as to hold the liquid crystal material in an oriented state. When a liquid crystal material is applied onto the sheet 1, it enters the pores 2 by capillary action and is oriented in the longitudinal direction of the pores by surface action on the inner surfaces of the pores. Since the longitudinal direction of the pores is oriented in a single direction, substantially all of the liquid crystal molecules within the pores of the sheet are oriented in a single direction.
When excess liquid crystal on the surface of the sheet is then removed, the liquid crystal within the pores remains intact and the surface of the sheet 1 feels dry. The sheet 1 as a whole may function as a substantially unidirectionally oriented liquid crystal layer.

The liquid crystal material can be introduced into only selected parts of the sheet 1 by printing. The remainder of the sheet can be filled with non-liquid crystal organics.

The liquid crystal substance includes a dichroic liquid crystal compound or a dichroic dye. The liquid crystal material may be nematic, cholesteric, smectic, or a mixture thereof.

FIG. 2 shows a color changing device using the dichroic polarizing sheet shown in FIG. The dichroic polarizing sheets 3, 11 of the present invention have polarization axes 4, 12
They are usually placed in contact with the twisted nematic liquid crystal cell 5 so that they are orthogonal to each other. The liquid crystal cell 5 has a layer of nematic liquid crystal material 12 microns thick sandwiched between glass slides 7, 8 whose inner surfaces are coated with electrodes 9, 10 in a sandwich configuration. The inner surfaces of the glass slides 7, 8 are unidirectionally abraded before assembly as a liquid crystal cell;
On the surface, liquid crystal molecules are oriented in the rubbing direction. The glass slides 7 and 8 are assembled so that the directions of rubbing are perpendicular to each other. Therefore, in a liquid crystal cell configured in this way, in the OFF state where no voltage is applied, the rubbing direction is from one glass slide to the other. In the past, the alignment direction of liquid crystal molecules was twisted by 90 degrees, and the linearly polarized light emitted from the white light source 13 and passed through the polarizing sheet 3 was changed to a polarized plane in the liquid crystal layer.
The light is rotated by 90 degrees, passes through a polarizing sheet 11 having a horizontal polarization axis 12, and is observed by an observer 14 as white light. On the other hand, in the on state where a voltage is applied, the liquid crystal molecules are aligned parallel to the electric field, so the liquid crystal cell 5 does not rotate the plane of polarization. Therefore, linearly polarized light having a vertical polarization plane is observed as colored light when it passes through the dichroic polarizing sheet 11 whose polarization axis is horizontal. This color depends on the liquid crystal material and the dye.

By appropriately selecting the liquid crystal material or dye, the polarizer of the present invention can also be used in a so-called twisted nematic display device in which a reflector is provided after one polarizer.

FIG. 3 shows the use of a composite polarizer sheet for three-dimensional display. As described above with respect to FIG. 1, the sheet may be filled with liquid crystal material by printing. With this method, for example, the width is 125μm, the interval is 125μm.
Narrow strips filled with m liquid crystal material are successively placed on the sheet. The pores of the sheet between the liquid crystal material-filled strips are filled with oil. The two sheets constructed in this manner so that the direction of the liquid crystal substance-filled strips are parallel and perpendicular to the longitudinal direction of the pores on the sheet are arranged so that the liquid crystal substance portions of each sheet do not overlap each other. , a composite sheet 27 is obtained having strips 28, 29 whose polarization axes alternate horizontally and vertically, respectively. This allows TV display 2
A display such as 6 may have alternating lines passing through the composite polarizing sheet 27 showing the image seen by the left eye and the image seen by the right eye. That is, for example, if an observer (not shown) wears glasses in which the polarization axis of one lens is vertical and the polarization axis of the other lens is horizontal, in each eye, the polarization axis will be different from that of each of the glasses. Only light emerging from the strip in the same direction as the polarization axis of the lens is observed. This allows the strips of the sheet 27 to be superimposed on the raster lines of the television for three-dimensional display.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a plastic material sheet used in the liquid crystal polarizer of the present invention, FIG. 2 is an explanatory diagram of a color changing device using the liquid crystal polarizer of the present invention, and FIG. FIG. 3 is an explanatory diagram of the use of a liquid crystal polarizer for three-dimensional display.

Claims (1)

[Claims] 1 consisting of a sheet of plastic material having a large number of open elongated pores aligned in a single direction and carrying a liquid crystal substance, said liquid crystal substance being dichroic or containing a dichroic dye, said pores being dichroic; A liquid crystal polarizer having a size slightly larger than the size of liquid crystal molecules so as to maintain the liquid crystal material as a highly oriented layer.