JPS6156398A - Projection type liquid crystal display unit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a projection type liquid crystal display device that uses an optical system to enlarge and project information displayed on a twisted nematic type liquid crystal display element.

Background technology Image information such as characters is displayed on a twisted nematec type liquid crystal display element, and this liquid crystal display element is irradiated with illumination.
Devices that use an optical system to enlarge and project images onto a screen are well known. When the voltage applied to the electrodes of a liquid crystal display element exceeds a threshold value, the ? ! Images are displayed using changes in the light transmittance of the liquid crystal interposed between the electrodes. The image is displayed by bright areas where the irradiated light passes through the liquid crystal display element, or by dark areas where light is blocked.

Problems to be Solved by the Invention In the prior art, the liquid crystal display device is set to be driven by selecting in advance either the bright area display or the dark area display as described above. Table 87 shows the information by inverting the bright and dark parts of the image. Yo78□kei. “
(1) An object of the present invention is to provide a projection type liquid crystal display device that can display information by easily reversing the bright and dark parts of an image.

Means for Solving the Problems According to the present invention, a single light source, a twisted nematic type liquid crystal display element, a condensing lens, and a screen are arranged in this order, and an axis perpendicular to the display surface of the liquid crystal display element is located from the light source. The optical axis of the parallel light and the optical axis of the condensing lens intersect, and the liquid crystal display element includes a common electrode, individual electrodes, and a liquid crystal interposed between these electrodes; The voltage between the individual electrode and the common electrode and the voltage between the other i individual electrode and the common electrode are determined when the transmittance of the liquid crystal is 78. The first operation operates in a range that increases as the inter-electrode voltage increases, the voltage between one individual electrode and the common electrode, and the voltage between the other individual electrode and the common electrode are determined by the transmittance of the liquid crystal. This is a projection type liquid crystal display device characterized in that the liquid crystal is driven by switching between a second operation that operates in a range that decreases as the inter-electrode voltage increases.

According to the present invention, the axis line that is perpendicular to the display surface of the liquid crystal display element,
The optical axis of the parallel light from the light source and the optical axis of the condensing lens are crossed, and the transmittance of the liquid crystal changes as the voltage applied between the electrodes of the liquid crystal display element changes. Then, image information can be displayed by easily selecting between display using bright areas through which light passes and display using dark areas where light is blocked.

Embodiment $1 FIG. 1 is a diagram showing the configuration of the present invention. As shown by arrow A, parallel light from a light source 1 is irradiated onto the display surface of the liquid crystal display element 2 along an axis iK perpendicular to the display surface of the liquid crystal display element 2. The light that has passed through the bright area of the liquid crystal display element 2 is condensed by a condenser lens 3 that is arranged to be inclined with respect to the axis of the light MB by an angle α1 related to a viewing angle θ, which will be described later. A screen is arranged in front of the condenser lens 3, and an enlarged image of the liquid crystal display element 2 is projected onto the surface of the screen.

FIG. 2 is a diagram for explaining the characteristics of the liquid crystal display element 2 shown in FIGS. The liquid crystal of this liquid crystal display element 2 is of a twisted nematic field effect type, and its transmittance changes depending on the viewing angle θ with respect to the law KfACK perpendicular to the display surface of the liquid crystal display element 2. FIG. 3 is a simplified cross-sectional view of the liquid crystal display element 2. As shown in FIG. LCD 5
are enclosed in a space formed by two transparent substrates 6, 7 and spacers 8, 9, and a common electrode P1 arranged on the substrate 6 and individual electrodes P2 . It is immobilized by the voltage applied between it and P3. Figure 4 shows the applied voltage V
3 is a diagram showing the relationship between the transmissivity T of the liquid crystal 5 and the anti-transmittance T of the liquid crystal 5. FIG. Figure 4 (
1) shows the characteristics when the viewing angle θ shown in FIG. 2 is zero, and FIG. 4(2) shows the characteristics when the viewing angle θ is 40 to 45 degrees. In FIG. 4 (1), when the applied voltage V is made thicker than the threshold value, the transmissivity T increases,
When the voltage exceeds that voltage, the anti-transmittance T shows a substantially constant value. Normally, images are displayed using such characteristics, but in the present invention, the characteristics shown in No. 41iU(2) are used. In FIG. 4 (2), when the applied voltage V exceeds the voltage v1, the anti-transmittance T increases from the value T1, and at the voltage v2, the value T
It becomes 2. The anti-transmittance T decreases between voltages V2 and V3, and increases again to a constant value T3 when the voltage exceeds 73. Voltages Vl, V2 . The value of V3 is determined by the liquid crystal material, and such characteristics can be realized by appropriately selecting the rubbing angle of the alignment film and the absorption axis angle of the polarizing plate constituting the liquid crystal display element 2.

Figure 5 shows the common electrode P1 of the liquid crystal display element 2 and the individual 'IEN'.
It is a figure which shows the waveform of the voltage V applied between P2 and P3. FIG. 5(1) shows the voltage waveform applied between the common electrode P1 and the individual electrode RP2, and the voltage v1
The liquid JAS is transparent when the voltage is V2, and the liquid crystal 5 is transparent when the voltage is V2.
becomes opaque. FIG. 5(2) shows the waveform of the voltage applied between the electrodes PL and 23, where the voltage V1 is constant and the liquid crystal 5 is transparent.

Figure @6 is similar to the waveform diagram of the applied voltage V shown in Figure 5, but the applied voltage value is different. Figure 6 (1) shows the voltage waveform between the voltages fIP1 and P2, and when the voltage is v2, the liquid crystal 5 is opaque;
3, the liquid crystal 5 becomes transparent. Figure 6 (2) shows the electrode P.
The voltage waveform between L and 23 is shown, and the voltage v2 is constant and the liquid crystal 5 is opaque.

If an image is displayed using a large number of pixels by taking advantage of the above-mentioned characteristics, the result will be as shown in FIG. 7, for example. Figure 5 (1
) When a voltage waveform as shown in Figure 7 is applied to a selected pixel of an image, an image with dark areas through which no light passes is displayed as shown in Figure (1).

At this time, when the voltage waveform shown in No. 61N (1) is applied to the selected pixel, an image with bright parts through which light passes is displayed as shown in FIG. 7 (2).

In other words, an image with the dark and bright areas reversed is displayed. By simply changing the voltage value without converting the voltage waveform between electrodes PI and P2 and electrode P1゜23,
l! ii) It becomes possible to invert the image. In the present invention, if the liquid crystal display element 2 with a large number of pixels is used, the displayed image will be clear and the effect of inversion will be great.

@8 Figure is a configuration diagram for explaining another embodiment of the present invention. The liquid crystal display element 2 is arranged so that the parallel light from the light source 1 and the I (value line) perpendicular to the display surface of the liquid crystal display element 2 are inclined by an angle α2 with respect to 'I J. You may.

FIG. 9 is a block diagram d) for explaining still another embodiment of the present invention [rJ'J. The IIdI line perpendicular to the display surface of the liquid crystal display element 2 and the optical axis B of the condenser lens 3 coincide, and the parallel light from the light source 1 is tilted at an angle α3 with respect to the axis of the liquid crystal display element 2. The present invention can also be realized by irradiating the display surface of the liquid crystal display element 2.

As another embodiment of the present invention, the angle α1. α2° and α3 may be selected in relation to each other.
, 11 The present invention is of a projection type, and due to the combination of the rubbing angle in the liquid crystal display element 2 and the absorption axis angle of the polarizing plate, there is no need to worry about the color tone of the image, which is a problem with other display methods.

Effects As described above, according to the present invention, information can be easily displayed by reversing the image display in bright areas and the image display in dark areas by simply selecting and switching the applied voltages for driving the liquid crystal. can.

[Brief explanation of drawings]

Figure 1 is a diagram showing the configuration of the present invention, Figure 2 is a diagram for explaining the viewing angle θ, Figure 3 is a sectional view showing a simplified configuration of the liquid crystal display element 2, and Figure 4 is a diagram showing the simplified configuration of the liquid crystal display element 2. FIG. 5 is a waveform diagram of the voltage applied to the electrodes of the liquid crystal display element 2, and FIG.
The figure is a waveform diagram shown by changing the applied voltage in Figure 5, Figure 4\S7 is a diagram showing an example of the screen Φ display, and Figure 38 is a diagram showing t((j or) of another embodiment of the present invention. , FIG. 9 shows the configuration of still another embodiment of the present invention. 1... Light source, 2... Liquid crystal display element, 3... Condensing lens, 4... Screen, PI, P2.P3...Electrode, α1゜α2.α3...Angle Figure 2 Figure 3 Figure 4 Figure 5 Roro■口口Roro日口■fourroro關■RororororokakurorororoIN日口m日■RororoRo■III口 1 0mIIg口Figure 7

Claims (1)

[Claims] In a projection type liquid crystal display device in which a light source, a twisted nematic type liquid crystal display element, a condensing lens, and a screen are arranged in this order, an axis perpendicular to the display surface of the liquid crystal display element, the light source The optical axis of the parallel light from and the optical axis of the condensing lens intersect, and the liquid crystal display element includes a common electrode, individual electrodes, and a liquid crystal interposed between these electrodes; A first operation in which the voltage between the individual electrode and the common electrode and the voltage between the other individual electrode and the common electrode are operated in a range in which the transmittance of the liquid crystal increases as the inter-electrode voltage increases; and a second operation in which the transmittance of the liquid crystal decreases as the inter-electrode voltage increases. A projection type liquid crystal display device characterized in that a liquid crystal is driven by a projection type liquid crystal display device.