JPH0268521A - Ferroelectric liquid crystal device - Google Patents

Abstract

PURPOSE:To obtain the ferroelectric liquid crystal device which is prevented from generating a color shade and varying is coloring without spoiling a bright display state by providing a light scattering layer to at least one of a couple of substrate between which a ferroelectric liquid crystal layer of <=5MUm thickness is sandwiched. CONSTITUTION:The liquid crystal device has the ferroelectric liquid crystal layer 3 of <=5mum thickness sandwiched between the couple of glass substrates 2a and 2b having rough surfaces 1a and 1b, and a three-wavelength type fluorescent lamp light source 4 is provided behind the substrate 2. Those rough surfaces 1a and 1b operate as the light scattering layer. Namely, the phases of light which is incident on a liquid crystal cell from the light source 4 through a polarizing plate 11b and light which is reflected repeatedly in the liquid crystal cell are disordered by the rough surfaces 1a and 1b, so that any interference peak due to interfacial reflection is not generated. Consequently, even when a display is made by using the high-brightness multi-wavelength light source 4 as a back surface light source, the color shade and variation in coloring are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a liquid crystal device using a ferroelectric liquid crystal, and particularly to a ferroelectric liquid crystal device in which color unevenness is suppressed.

[Prior art] Clark and Lagerwall have developed an Applied Phys.
ics Letters Vol. 36, No. 11 (June 1, 1980) P, 899-901, or U.S. Pat. No. 4,367,924, U.S. Pat.
izedferroelectric 1iquid
revealed bistable ferroelectric liquid crystals. This bistable ferroelectric liquid crystal is arranged between a pair of substrates with a spacing sufficiently small to suppress the formation of a helical alignment structure of liquid crystal molecules in the chiral smectic phase in the bulk state, and is composed of a plurality of liquid crystal molecules. This was achieved by aligning vertical molecular layers organized in one direction.

However, the actual transparency of ferroelectric liquid crystal cells is not sufficiently high, and therefore it is necessary to use a high-brightness backlight source when displaying. In general, such high-intensity light sources include light sources that produce a sharp specific energy (%) peak, and in particular, phosphor light sources that use at least two types of phosphors with different emission wavelengths (for example, a second phosphor light source). Toshiba rFL40s, which has the characteristics shown in the figure.
S-EEX37-SJ) is known.

[Problems to be Solved by the Invention] However, when such a light source is used as a back light source for the above-mentioned ferroelectric liquid crystal panel (cell), color unevenness may occur due to uneven thickness of the liquid crystal layer, and observation may be difficult. This has caused problems such as changes in color over the entire panel depending on changes in direction.

SUMMARY OF THE INVENTION In view of the problems of the prior art, an object of the present invention is to provide a ferroelectric liquid crystal device that prevents the occurrence of color unevenness and changes in hue without impairing the bright display state.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a ferroelectric liquid crystal cell having a pair of substrates and a ferroelectric liquid crystal layer having a thickness of 5 μm or less sandwiched between them, and In a ferroelectric liquid crystal device including a fluorescent lamp light source having at least two types of phosphors having different emission wavelengths, at least one of the pair of substrates is provided with a light scattering layer.

As the light scattering layer, for example, a surface (layer) of a transparent conductor or a transparent insulator included in the substrate or a roughened interface thereof can be used.

[Operation] In this configuration, the phase of the light that enters the ferroelectric liquid crystal cell from the light source and the light that is multiple-reflected within the cell is disturbed by the light scattering layer, and no interference peak resulting from interface reflection occurs. Therefore, a display is produced in which color unevenness and changes in hue are suppressed compared to the conventional case.

[Example] Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a schematic cross-sectional view showing the structure of a ferroelectric liquid crystal device according to an embodiment of the present invention. As shown in the figure, this liquid crystal device includes a pair of glass substrates 2a and 2b having rough surfaces 1a and 1b, respectively, and a ferroelectric liquid crystal layer 3 sandwiched between them and having a thickness of 5 μm or less. A three-wavelength fluorescent lamp light source 4 is provided behind the cell and the substrate 2b.

The glass substrates 2a and 2b are each made of ITO forming a transparent conductor for controlling the orientation of the ferroelectric liquid crystal.
(indium tin oxide) layers 5a and 5b
, 5i02 layers 6a and 6b as insulating layers, and alignment films 7a and 7b in contact with the ferroelectric liquid crystal layer 3.

The rough surfaces 1a and 1b are the surfaces of the glass substrates 2a and 2b on the opposing sides made rough by physical or chemical means, but on the contrary, the surfaces of ffl+7, or IT OffJ5a, 5b Ya 5
The surfaces or interfaces of the in2 layers 6a, 6b may be made rough. Furthermore, it may be provided only on either side of the substrate 2a or 2b.

Further, the substrate 2b further includes a color filter 8 and a passivation layer 9, and the light source 4 includes a reflecting plate io that reflects the emitted light toward the liquid crystal cell. Polarizing plates 11a and flb are provided on both sides of the liquid crystal cell.

In this configuration, the rough surfaces 1a and 1b act as light scattering layers. That is, the phases of the light that enters the ferroelectric liquid crystal cell (panel) from the light source 4 via the polarizing plate 11b and the light that is multiple-reflected within the ferroelectric liquid crystal cell are disturbed by the rough surfaces 1a and 1b, and the interface No interference peaks due to reflection occur.

Moreover, the color filter 8 also acts as a second light scattering layer. That is, in the color filter 8, since the pigment strongly scatters light, the scattering effect by the rough surfaces 1a and 1b is strengthened, and the suppression of color unevenness is further promoted.

In this way, according to this embodiment, an FLC (ferroelectric liquid crystal) display with excellent display quality is realized.

[Effects of the Invention] As explained above, according to the present invention, even when a high-brightness multi-wavelength light source is used as a backlight source for display in a ferroelectric liquid crystal device, occurrence of color unevenness and changes in hue can be suppressed. be able to.

2a, 2b: substrate, 3: Ferroelectric liquid crystal layer, 4: light source, 5a, 5b: 170 layers, 5a, 6b: SiO2 layer, 7a, 7b: alignment film, 8: Color filter, 9: Passivation layer, 10: reflective film, 11s, llb: (Ji light board.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the configuration of a ferroelectric liquid crystal device according to an embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view of a phosphor light source used as a backlight source of the ferroelectric liquid crystal device. It is a graph showing an example of characteristics.

Claims (2)

[Claims] (1) A pair of substrates and a thickness of 5 μm sandwiched between them
In a ferroelectric liquid crystal device comprising a ferroelectric liquid crystal cell having the following ferroelectric liquid crystal layer and a fluorescent lamp light source having at least two types of phosphors having different emission wavelengths, at least one of the pair of substrates has a A ferroelectric liquid crystal device comprising a light scattering layer. (2) the substrate includes a transparent conductor and a transparent insulator;
2. The ferroelectric liquid crystal device according to claim 1, wherein the light scattering layer is a roughened surface or boundary surface of the transparent conductor or transparent insulator.