JPS6321908B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a guest-host type liquid crystal display panel that uses liquid crystal to which dichroic dye is added to display 7-segment numeric characters in color on a white background, and relates to a liquid crystal display panel that has novel pattern electrodes. Guest-host type liquid crystal display panels that use cholesteric-nematic mixed liquid crystals containing dichroic dyes do not require polarizing plates compared to other liquid crystal displays that use electro-optic effects, so the visible angle is 140° or more in solid angle. It has the advantage of being able to display a wide range of bright colors. The operating principle will be briefly described below. The surface of the liquid crystal molecules in contact with the electrode substrate is subjected to vertical alignment treatment, and in this case, when no voltage is applied, the liquid crystal molecules are vertically aligned in the vicinity of the electrode substrate, and in the bulk, they are aligned along the helical axis. If it is perpendicular to the electrode substrate, it has a rotational orientation. The optical axis of the dichroic dye molecules has a similar helical orientation in accordance with the helical orientation of the liquid crystal molecules in the bulk, and the incident light is in the unique wavelength range of the added dichroic dye. It is absorbed and appears colored to the observer. When a voltage higher than the threshold voltage is applied, a phase transition from the cholesteric phase to the nematic phase occurs due to electric field induction, the liquid crystal molecules become oriented perpendicular to the electrode substrate, the optical axis of the dichroic dye also becomes perpendicular, and the incident light becomes dichroic. Since it is parallel to the optical axis of the colored dye, it appears to the observer as white (the color of the reflector). As is clear from the above, this type of liquid crystal panel erases color when voltage is applied, so in order to display colored characters on a white background (positive display), the electrode pattern must be devised. There is a need.
Figure 1 shows a conventional positive display pattern electrode, and Figure 1-1 shows a front electrode substrate pattern electrode, which is divided into nine parts as shown by solid lines. . FIG. 1-2 shows the pattern electrode of the back electrode substrate, which is divided into eight parts as shown by solid lines. The solid lines are areas without electrodes, but the line width is 20 to 100 μm, and each electrode pattern is insulated. The etching technique for patterned electrodes 1h and 1i is difficult because it is not possible to make a large space between segment a and segment b and between segment e and segment d due to the design when displaying segments. To drive the liquid crystal display panel described above, at least 16 output drive circuits are required. SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display panel in which the number of divided pattern electrodes is reduced and the etching process of the pattern electrodes is easy. The liquid crystal display panel of the present invention is a guest-host type liquid crystal display panel that displays 7-segment numbers using colored characters on a white background. An electrode substrate A in which divided electrodes are formed on the entire surface of the display part, some segment electrode parts of the seven segment electrodes of the electrode substrate A, and segment electrodes other than the part of the segment electrodes. A common electrode corresponding to the electrode portion of the lead portion, a common electrode corresponding to the electrode portion of the lead portion of the some of the segment electrodes, and a common electrode corresponding to the segment electrode portion other than the some of the segment electrodes. The electrode is composed of an electrode substrate B formed on the entire surface of the display section, and a liquid crystal material added with a dichroic dye and filled between the two electrode substrates A and B. The liquid crystal display panel of the present invention will be explained in detail below. FIG. 2 schematically shows a liquid crystal display panel according to an embodiment used to explain the liquid crystal display panel of the present invention.
5-2 is coated, but electrodes 5-1 and 5-2
They are insulated from each other with a spacing of 50 μm.
A transparent electrode 8 is coated on the glass substrate 9, and a reflective plate 10 is provided on the back surface of the glass substrate 9.
Vertical alignment films (FS150 film manufactured by Dainippon Ink) 6 and 7 are coated on the surface in contact with the liquid crystal molecules. FS150
The film is formed by immersing the electrode substrate in an aqueous solution of 0.03 weight percent FS150, then drying and baking at 120°C for 15 minutes. If the same electric signal is applied to the transparent electrodes 8 and 5-2, and an electric signal different from the electric signal applied to the transparent electrode 8 is applied to the transparent electrode 5-1, the transparent electrode Liquid crystal molecules 11-1 corresponding to 5-1 are vertically aligned. As described above, in the vertically oriented region, light absorption by the dichroic dye does not occur, so the white color of the reflecting plate 10 is observed. No voltage is applied to the region of the liquid crystal molecules 11-2, and the region appears colored. The patterned electrode used in one embodiment will be explained in detail below with reference to FIG. In this example, the electrode substrate A was the front electrode substrate, and the electrode substrate B was the back electrode substrate. Figure 3-1 is a diagram showing pattern electrodes on the front electrode substrate;
Figure 2 is a diagram showing pattern electrodes on the back electrode substrate. The 7-segment numerical display is
a, b, c, surrounded by solid lines and dotted lines shown in Figure 1.
It is displayed in 7 segments: d, e, f, and g. In the figure, the solid line has a line width of 50 μm and indicates that no transparent electrode is attached, but as shown in the figure, the electrodes on the front electrode substrate are 3a, 3b, 3c, 3d, 3e, 3.
It is divided into seven pattern electrodes of f and 3g. The electrode in the shaded area in the figure surrounded by segments a, b, c, d, e, f, and g is the pattern electrode 3g.
The electrodes on the back electrode substrate included in the pattern correspond to the four segments a, b, c, and d of the front electrode substrate and the portions of pattern electrodes 3e, 3f, and 3g excluding segments e, f, and g, respectively. It is divided into two parts: the electrode and the other part of the pattern electrode. Therefore, the patterned electrode explained in this example has a small number of electrode divisions, and moreover,
Since the hatched portion shown in FIG. 1 is included in the pattern electrode 3g, etching can be easily performed. Further, this embodiment has the advantage that the number of output drive circuits for driving the liquid crystal display panel is only nine. In the above embodiment, one digit was explained, but in order to display n-digit numbers, consider that the electrodes on the front electrode substrate are for one digit as shown in Figure 3-1, and use the same method to display n-digit numbers. For the back electrode, it is sufficient to use a common pattern electrode for each digit.Therefore, even if the number of digits increases, the electrode on the back electrode substrate can be divided into two electrode patterns, and n-digit numbers can be displayed. The number of output drive circuits in this case is (7n+2) circuits. The liquid crystal display panel of the present invention has been described above using an example. Below, a method for driving the liquid crystal display panel of this example will be explained in detail. An electric signal S1 is applied to the pattern electrode of the back electrode substrate, and an electric signal S2 is applied to the pattern electrode. It is assumed that the electrical signal S1 and the electrical signal S2 are not the same.
An electric signal S2 is applied to the pattern electrodes 3e, 3f, and 3g of the front electrode substrate when display is selected, and an electric signal S3 is applied when display is not selected. Electrical signal S3 is different from electrical signal S1 and electrical signal S2. When such an electric signal is applied, a voltage is applied to the segments e, f, and g by the electric signal applied to the pattern electrode and the electric signal applied to the pattern electrodes 3e, 3f, and 3g, respectively.
When selecting the display, since it is the same electrical signal S2,
No voltage is applied and therefore it is colored, but on the other hand
When the display is not selected, a voltage waveform G is applied using different electric signals S2 and S3, but if the effective voltage of this voltage waveform G is set to be equal to or higher than the threshold voltage value, no coloring occurs. The facing portions of the pattern electrodes and pattern electrodes 3e, 3f, and 3g are lead portions of segments e, f, and g, but electrical signals S
1 and electric signal S2 or electric signal S3, a voltage waveform GL is applied, but if the effective voltage of this voltage waveform GL is made equal to or higher than the threshold voltage value, no coloring occurs.
An electric signal S1 is applied to each of the front electrode substrates 3a, 3b, 3c, and 3d when display is selected, and an electric signal S4 is applied when display is not selected. Electrical signal S4 is different from electrical signal S1 and electrical signal S2. When applying such an electric signal, segments a,
b, c, d, the electric signals applied to the pattern electrodes and the pattern electrodes 3a, 3b, 3c, 3, respectively.
A voltage is applied by the electric signal applied to each of d, but when the display is selected, the same electric signal S1 is applied, so no voltage is applied, and therefore it is colored. On the other hand, when the display is not selected, a different electric signal is applied. S1
A voltage waveform H is applied by the electric signal S4, but if the effective voltage of this voltage waveform H is set to be equal to or higher than the threshold voltage, no coloring occurs. The facing portions of the pattern electrodes and the pattern electrodes 3a, 3b, 3c, and 3d are the lead portions of each of the segments a, b, c, and d, and the electrical signals S2 and S1
Alternatively, the voltage waveform HL is applied by the electric signal S4, but if the effective voltage of this voltage waveform HL is made equal to or higher than the threshold voltage, no coloring occurs. The method for driving the liquid crystal display panel of the embodiment of the liquid crystal display panel of the present invention has been described above, but only the display selection segment is colored, the others are not colored, and the lead portion of each segment serves as the background. Therefore, a positive display in which display segments with a white background are colored is
This can be achieved by using the liquid crystal display panel of the embodiment.
Table 1 shows the electrical signals applied to each pattern electrode when numbers 0 to 9 are displayed.

[Table] The present invention has been described above using examples, but the pattern electrode of the back electrode substrate in the example and the division into two by the pattern electrode are only examples, and the method of dividing the back electrode substrate into two is described in the claims. There are many conditions.For example, in the example, the parts corresponding to segments a, b, c, d, and e on the front electrode board and the parts corresponding to the lead parts of segments f and g are used as pattern electrodes on the back electrode board. year,
Needless to say, the remaining portion may be used as a pattern electrode. As is clear from the above description, according to the present invention, a positive display liquid crystal display device with a small number of drive circuits can be obtained.

[Brief explanation of the drawing]

FIG. 1 shows the pattern electrodes of a conventional liquid crystal display panel, 1 shows the pattern electrodes on the front electrode substrate, 2 shows the pattern electrodes on the back electrode substrate, and FIG. FIG. 3 is a schematic cross-sectional view of a liquid crystal display panel structure used in an example, and shows pattern electrodes of a panel used in an example of the present invention. 1 is a pattern electrode diagram of a front electrode substrate; 2
shows the pattern electrode diagram of the back electrode substrate. 1st
3, a, b, c, d, e, f, g are segment parts, 4, 9 are glass substrates, 5-1, 5-
2 and 8 are electrode patterns, 6 and 7 are vertical alignment films, 1
0 is a reflecting plate, and 11-1 and 11-2 are liquid crystal molecules (schematic alignment diagram).

Claims (1)

[Claims] 1. By overlapping a pair of electrode substrates A and B,
In a liquid crystal display panel forming a display area in the shape of a "Sun" character, (a) the electrode substrate A has six display parts, excluding the horizontal bar display part in the middle, of the display part in the shape of a "Sun"character; The first to sixth electrodes 3a, 3 each include a portion corresponding to the electrode and a lead portion that leads the electrode to the outside of the substrate.
b, 3c, 3d, 3e, 3f, a part surrounded by the "day" shaped display part, a part corresponding to the horizontal bar display part in the middle, and a lead part that leads this out of the board. (b) The electrode substrate B has four parts of the "Sun"-shaped display part excluding the horizontal bar display part in the middle and the two vertical bar display parts on the left side. of the fifth to seventh electrodes 3e, 3f, and 3g, the two on the left side
A first pattern electrode corresponding to a portion of the book excluding the vertical bar display portion and a horizontal bar display portion and a second pattern electrode corresponding to a portion excluding the first pattern electrode are formed. LCD display panel.