JPS5975226A - Gradation generation system of liquid crystal display panel - Google Patents

Abstract

PURPOSE:To vary the color tone (saturation) of a display part according to display contents by varying the gradation of a liquid crystal panel electrically. CONSTITUTION:Such a reflecting plate 2 that a color filter is superposed upon a mirror surface is provided on the reverse side of a phase transition type liquid crystal display panel which varies in light transmittivity continuously with a voltage and its view side is irradiated with light. A voltage V1 is applied to the 1st display point of the liquid crystal display panel 1 and a voltage V2 is applied to the 2nd display point. Then, 25% the irradiation light to the 1st display point and about 80% the irradiation light to the 2nd display point return to the view side. The color tone on the display surface is sharpest at the 2nd display point and lower-saturation (whity) color tone is obtained in the order of the 1st display point and a nondisplay point. Thus, the gradation of display color at an optional point on the liquid crystal display panel is varied without using any mechanical mechanism, and the performance is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to display mounting using liquid crystals, and particularly to a method for imparting gradations to display colors.

(b) Background of the technology Liquid crystal display panels are becoming widely used as display elements that can be driven at low voltages, but among these, the so-called phase change type display is difficult to display because it does not require a polarizing plate. It is bright and features a wide viewing angle.

(C) Prior Art and Problems In general, since liquid crystal display panels utilize the transmission or reflection of external light by themselves, the displayed colors cannot be changed by appropriately selecting color filters or polarizing plates. Can be done.

Therefore, it is easy to partially change the display color depending on the displayed content, and areas that require special attention are displayed in red, for example, and other areas are displayed in blue, etc. .

However, in the above method, the color and brightness of the display area are fixed depending on the color filter or polarizing plate used, and in order to change the color tone each time the display content changes, the color filter must be changed. It had the disadvantage of requiring mechanical mechanisms such as

(d) Purpose of the Invention The present invention electrically changes the gradation of the liquid crystal display panel to adjust the color tone (saturation) of the display area according to the displayed content.
The purpose is to provide a method that can change the

<e> Structure of the Invention The present invention provides a phase change type liquid crystal display panel in which the light transmittance changes continuously depending on a voltage, in which means for transmitting colored light is provided in the liquid crystal display panel, and the liquid crystal display panel is provided with a means for transmitting colored light. It is characterized in that by applying voltages of different levels depending on the display location on the panel, different color tones are displayed for each display location or at different display timings.

(f) Examples of the invention Embodiments of the present invention will be described below with reference to the drawings.

Phase change type liquid crystal display panels are a mixture of nematic liquid crystal and cholesterlink liquid crystal, and when no voltage is applied, the light that passes through the liquid crystal layer is scattered by the cholesterlink liquid crystal, resulting in a cloudy appearance. On the other hand, when a voltage is applied, the cholesteric liquid crystal has a molecular alignment parallel to the electric field, so that the entire liquid crystal layer has the property of becoming transparent. As a result, the relationship between the intensity of light transmitted through the liquid crystal layer and the applied voltage is as shown in FIG.

Here, the liquid crystal display panel is irradiated with light using the configuration shown in FIG.

Fig. 2 (A) shows a case where a reflective plate 2, such as a mirror surface with a color filter layered on it, is provided on the back side of the viewing side of the liquid crystal display panel 1, and light is irradiated from the viewing side, and the irradiated light is generally used indoors. The light itself is used. Further, (B) shows a case in which a color filter 4 is provided on the rear side of the viewing side of the liquid crystal display panel 3, and light is further irradiated from the rear side using, for example, an incandescent light bulb 5.

In the configuration shown in FIG. 2, the voltage ν1 shown in FIG. 1 is applied to the first display location of the liquid crystal display panel 1, and the voltage ν2 is applied to the second display location.

As a result, in the case of FIG. 2A, 25% of the irradiated light returns to the viewing side at the first display location, and approximately 80% of the irradiated light returns to the viewing side at the second display location.

On the other hand, among the light that enters the entire surface of the liquid crystal display panel 1, the intensity of the light that is scattered without passing through the liquid crystal layer is greatest in non-display areas (areas where there are no electrodes or display areas where the applied voltage is O). The size is the smallest at the second display location, and the size is intermediate between these at the first display location.

Therefore, the color tone on the display surface becomes clearest at the second display location, and becomes less saturated (that is, whitish) in the order of the first display location and the non-display location.

In the above, by setting the applied voltage level to values other than vl and ν2, the color tone of the display area can be changed to more gradations, and the number of display areas with different gradations can also be increased.

FIG. 3 is a diagram showing an example of response speed characteristics of transmitted light intensity when a rectangular wave voltage is applied to a phase change type liquid crystal display panel, in which (A) is a rising characteristic and (B) is a falling characteristic. It is a characteristic. In the liquid crystal display panel of this example, both the rising and falling response speeds (transmitted light intensity from the minimum value to 90% of the maximum value, and from the maximum value to 10% of the maximum value)
%) is 4,5+ms
It is.

Therefore, in a configuration similar to that shown in Fig. 2, the duration of the rectangular wave voltage (
1) and the repetition period (T), that is, by applying rectangular wave voltages having different values, t/T, it is possible to change the color tone of these display locations. However, it is assumed that the repetition frequency (T) is 4.5≦T (ms).

FIG. 4 is a diagram showing an example of the waveform of the rectangular wave voltage in the above case, in which (A) shows a duration longer than 4.5 ms (
tl), (B) is a waveform with a duration (t2) greater than 4.5 ms, and (C) is a waveform with a duration of 0. The repetition period (T) in each figure is generally 4
．． It is set to be sufficiently longer than 5ms.

When the rectangular wave voltages shown in Figure 4 (A), (B), and (C) are applied to the first display location, second display location, and non-display location, respectively, the color tone at the first display location is the clearest. The color tone becomes less saturated (that is, whitish) in the order of the second display location and the defective location.

Furthermore, by controlling the waveform to change the duration (t2) in (B), the gradation of the displayed color can be changed, or by using another rectangular wave voltage having a duration different from t2. Needless to say, by preparing the display area, it is possible to increase the number of display areas with different gradations.

(g) Departure'! [If]According to the present invention, it is possible to change the gradation of displayed colors at any display location on a liquid crystal display panel without using a mechanical mechanism, and it is possible to improve the performance of a liquid crystal display device. At the same time, it has the effect of making its application expandable.

[Brief explanation of drawings]

Figure 1 is a diagram showing an example of the relationship between transmitted light intensity and applied voltage in a phase change type liquid crystal display panel, Figure 2 is a diagram showing the arrangement of display light coloring means, and Figure 3 is a diagram showing a one-phase transition. FIG. 4 is a diagram showing an example of response speed characteristics of a type of liquid crystal display panel, and FIG. 4 is a diagram showing an example of an applied voltage waveform. In the figure, 1 and 3 are liquid crystal display panels, 2 is a reflector, 4 is a color filter, and 5 is an incandescent light bulb.

Claims (1)

[Claims] In a phase change type liquid crystal display panel in which light transmittance changes continuously depending on voltage, the liquid crystal display panel is provided with a means for passing colored light, and the liquid crystal display panel is provided with a means for passing colored light, and the liquid crystal display panel is provided with a means for transmitting colored light at different levels depending on the display location on the liquid crystal display panel. A gradation method for a liquid crystal display panel characterized by displaying different colors at each display location or at different display timings by applying a voltage.