JPH01102527A - Liquid crystal shutter system - Google Patents

Abstract

PURPOSE:To constitute the title system so that an image is always viewed in some specific direction, and the image can be viewed or cannot be viewed in other specific direction in accordance with necessity by specifying the product DELTAnX(d) of a refractive index anisotropy DELTAn and liquid crystal layer thickness (d) of a nematic liquid crystal used for a liquid crystal display element. CONSTITUTION:The product DELTAnX(d) of a refractive index anisotropy DELTAn and liquid crystal layer thickness (d) of a nematic liquid crystal is limited to a range of about 0.5mum-about 1.1mum. Accordingly to such constitution, from an observer A who is positioned in roughly the left upper part 3 of an image display device 1, a display image can always be observed, and from an observer D who is position in about the right upper part 4, the display image can be observed or cannot be observed in accordance with necessity. In this regard, whether the display image can be observed from the observer D or not is controlled by a driving voltage applied to a liquid crystal shutter.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Application of Cmm Field of the Invention The present invention relates to an image display device using a liquid crystal display element as a shutter.

(Prior art) When darkening the brightness of an image on a CRT, etc., conventionally, the 0th
As shown in the figure, it was common to place an ND filter, a light control film, etc. in front of the image display device. In the case of such a system, the brightness of the displayed image is simply darkened uniformly, and if the position of the viewer is fixed, there is a problem that the shutter degree cannot be varied. Furthermore, when a dynamic scattering mode liquid crystal display element is used as a shutter, the shutter degree can be varied by switching the voltage, but with a dynamic scattering mode, the shutter due to scattering is applied to the image no matter where it is viewed from. Therefore, the image cannot be made visible or invisible depending on the observer's position. In other words, it does not have the function of greatly changing the shutter degree depending on the observation position.

[Problem that the invention seeks to solve]

As described above, the conventional technology has a problem in that the image is always visible from a certain direction, and it is not possible to make the image visible or invisible from other specific directions as needed. The present invention is intended to solve these problems, and its purpose is to always make the image visible from a certain direction, and to make it visible or invisible from other specific directions as needed. Our goal is to provide a liquid crystal shutter system that can

[Means for solving problems]

The liquid crystal shutter system of the present invention utilizes the twisted nematic effect as a liquid crystal display element used as a shutter, and solves the above-mentioned problem by limiting Δn×d to a range of approximately 0.5 μm to approximately 1.1 μm. It is something.

(Example) Figure m1 is a schematic diagram of a liquid crystal shutter system according to the present invention. In the figure, numeral 1 is an image display device such as a CRT, and numeral 2 is a liquid crystal shutter using the Rice Terrace nematic mode. In the case of the present invention, by limiting the Δn×d of the liquid crystal shutter 2 to a range of approximately 0°5 μm to approximately 1.1 μm, it is possible to The displayed image can be observed at all times, and the 4th observer located approximately at the upper right can view the displayed image or not as necessary. Note that whether or not the viewer 1) can observe the displayed image is controlled by a drive voltage applied to the liquid crystal shutter.

Figure 2 and Figure M3 show how the observer in the driver's seat and 4.
This shows an outline of the viewing angle range in which observers A and 3 in the passenger seat can observe CRT images under normal conditions. FIG. 2 shows a plan view, and FIG. 3 shows a side view. Image display on CRT etc. in cars HE! It would be beneficial for drivers and passengers if they could display road information or receive and display general broadcasts using the II (I). However, it is not safe for drivers to watch general broadcasts while driving. Therefore, it is necessary to devise a way to make general broadcasts, for example, so that while the vehicle is running, observer A in the passenger seat can watch it, but observer A in the driver's seat cannot. Of course, while the vehicle is stopped, both observer A and observer A must be able to see the displayed image. The present invention is aimed at optimizing the transmittance of the twisted nematic mode Δn×d whose structure is shown in the m4 diagram, the transmittance of the polarizing plate used, adjusting the drive voltage of the liquid crystal shutter, or the N-image display. By mixing the arrangement angle of the liquid crystal shutter with respect to the device, a liquid crystal shutter suitable for the above-mentioned applications is provided.

In Figure 4, 7 and 5 are S on the inside of glass, transparent film, etc.
6 is a lower substrate having a similar structure. The upper substrate and the lower substrate are sandwiched between the sealing material 7, and about 8"
"The twisted nematic liquid crystal 8 is sealed. 0 indicates the upper polarizing plate and 10 indicates the lower polarizing plate, and their polarization axes cross at the top and bottom. This twisted nematic mode is a low voltage, low power consumption mode. It is widely used as a display element for displays on calculators, watches, etc., and has a visual angle contrast characteristic of 12 (Fig. In other words, the direction in which the color becomes darker is called the clear vision direction. In the case of Fig. 5, the clear vision direction is set at the 0° direction, that is, the 3 o'clock direction. Note that the direction opposite to the clear vision direction is often I can't see it, that is, it's not very black.

The present invention basically utilizes the viewing angle dependence of this twisted nematic mode, so that an image can always be seen from a specific direction, and can be seen or hidden from other specific directions as needed. For example, if a liquid crystal shutter with the above-mentioned functions is required in the positional relationship shown in Figures 2 and 3, the clear viewing direction should be installed in the direction of the observer. In other words, if you want the shutter to function for the viewer, you just need to apply a sufficient voltage to the liquid crystal shutter to make it black, but in this case, the direction toward the viewer is almost opposite to the direction of clear vision. Since the LCD shutter hardly functions, the displayed image can be viewed.Next, if you want to view the displayed image from both the viewer's direction and the viewer's direction, you do not need to apply voltage to the LCD shutter. .However, Δn×d is approximately 0.5 μm to approximately 1.1 μm.
If you do not set it in the range of m, the shutter degree in the direction of the observer may be weak (and the displayed image will be visible, or the range where the sufficient shutter degree can be applied will become narrow, etc.). The shutter is also activated in the direction of A, causing problems such as the displayed image becoming dark and the coloring of the liquid crystal shutter becoming severe.

Table 1 summarizes the characteristics of the liquid crystal shutter with respect to changes in Δn×d. The LCD shutter in Table 1 has a transmittance of 38%.
, a polarizing plate with a polarization degree of 09.0% was used. Also, in the table, D
The side indicates the direction of the observer D' in FIG. 2 or 3, and the Δ side indicates the direction toward the observer in FIG. 2 or 3. Note that a square wave of 10V-6411z was used as the driving voltage. From Table 1, it can be seen that unless Δn×d is within the range of approximately 0.5 μm to approximately 1.1 μm, the characteristics as a liquid crystal shutter are insufficient.

Next, add black dichroic dye 1, '5 to sample No. 2.
When wt% was added, the contrast at 10V10V was 25.0770.12=208.0 tons, and the degree of contrast on the D side was improved, but other characteristics were almost unchanged. In other words, adding an appropriate amount of dichroic dye is effective in improving the shutter speed on the viewer's side.

[Example 1] Nematic liquid crystal ZLI-2078-000 from Merck & Co.
(Δn = 0.0087), using cell gap d
A prototype liquid crystal display element with a diameter of 7.0μ was fabricated. In this case, Δn
xd=0.0600.

Nao, is the polarizing plate royal? 1XIa LC, -81-18
3 was used. This liquid crystal display element was used as a shutter of a 6 inch/inch CRT and was arranged as shown in Figure rn1. When this liquid crystal shutter system was observed from the positions shown in Figures 2 and 3, it was found that when the voltage applied to the liquid crystal shutter is OV, both from the viewer's side and from the viewer's side. The CRT display image looked good. Next, when a driving voltage of 10V was applied to the liquid crystal shutter, the CRT display image was good (visible and had almost no color change) from the observer's side, but from the observer's side CRT
The displayed image was almost invisible. Note that the front contrast of this example is l0V10V=28.3510.1
5=180.0.

(Example 2) Nippon Kayaku's black dichroic dye LCD-425 was added to Merck's nematic liquid crystal ZLI-2978-000 at 1.5
A liquid crystal display element with a cell gap of 7.0 .mu.m was prototyped by adding wt%. In this case, Δn X d , = 0゜0
It will be 600. In addition, the polarizing plate is LC manufactured by Royal FF1, -
81-183 was used. This liquid crystal display element
It was used as an RT shutter and arranged as shown in Figure 1. When this liquid crystal shutter system was observed from the positions shown in Figures 2 and 3, it was found that when the voltage applied to the liquid crystal shutter was OV, the CRT The displayed image looked good. next,
When IOV driving voltage is applied to the liquid crystal shutter,
The CRT display image looks good from the observer's side, and
Although there was no color change, the displayed image on the CRT was completely invisible to the observer. Note that the front contrast of this example is 1.0V10V=25.7310.12=2
It was 14°4.

In the embodiments described above, the relative positions of the image display device and the observer side and the observer A side are as shown in FIGS. 2 and 3, but Δnxd is approximately 0.5 μm even in other cases. If it is within the range of 1.1 μm from It is possible to make it visible or invisible from a specific direction as necessary.

〔Effect of the invention〕

As described above, according to the present invention, an image is always visible from a certain direction, and can be made visible or invisible from other specific directions as needed. In addition, if the liquid crystal display system of the present invention is installed in an automobile, it will be effective from the viewpoint of safety.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a liquid crystal shutter system according to the present invention. Figures 2 and 3 are diagrams schematically showing the viewing angle range when the present invention is mounted on an automobile. FIG. 4 is a diagram showing the configuration of a twisted nematic cord. Figure 3115 is a diagram showing the viewing angle contrast characteristics of twisted nematic mode. FIG. 6 is a schematic diagram of a conventional shutter system. 1... Image display device 2... Liquid crystal shutter 3... Observer A 4... Observer D 5... Upper substrate 6... Lower substrate 7... Seal material 8... Nematic Liquid crystal 0...Upper polarizing plate 10...Lower polarizing plate 11...CRT 12...Viewing angle and last characteristics Above Fig. 2 Fig. 4 9σ Fig. 5 Fig. 6

Claims (1)

[Claims] 1) In a system in which a liquid crystal display element is arranged in front of an image display device and the brightness of a displayed image is controlled by changing the driving voltage of the liquid crystal display element, a twisted nematic liquid crystal display element is used as the liquid crystal display element. By utilizing this effect, the product Δn×d of the refractive index anisotropy Δn of the nematic liquid crystal used in the liquid crystal display element and the liquid crystal layer thickness d is in the range of about 0.5 μm to about 1.1 μm. LCD shutter system. 2) The liquid crystal shutter system according to claim 1, wherein a dichroic dye is added to the nematic liquid crystal.