JPS6321196B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a guest-host type liquid crystal display panel that displays 7-segment numbers with colored characters on a white background using a liquid crystal containing a dichroic dye.The present invention relates to a liquid crystal display panel having novel pattern electrodes and a drive for this liquid crystal display panel. Regarding the method. 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 the same as the solid angle.
It has the advantage of being wider than 140 degrees and capable of displaying 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 near the electrode substrate, and spirally in the bulk. If the axis is perpendicular to the electrode substrate, it is in the rotating direction. The optical axis of the dichroic dye molecules has a similar helical orientation according to the helical orientation of the liquid crystal molecules in the bulk, and the incident light is light in the specific wavelength range of the added dichroic dye. is absorbed and appears colored to the observer. When a voltage higher than the threshold voltage is applied, a phase transition from a cholesteric phase to a nematic phase occurs due to electrical effect 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 is Since it is parallel to the optical axis of the dichroic dye, it appears to the observer as white (the color of the reflector). As is clear from what has been said above,
Since this type of liquid crystal display panel erases its color by applying a voltage, it is necessary to devise an electrode pattern in order to display colored characters on a white background (positive display). Figure 1 shows a conventional positive display pattern electrode, and Figure 1-1 shows the pattern electrode of the electrode substrate, 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. Due to the design when displaying segments, it is not possible to make a large space between segment a and segment b, and between segment e and segment d, so pattern electrode 1
Etching technology for h, 1i is difficult. that's all,
When driving 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, and to provide a driving method suitable for this liquid crystal display panel. The present invention provides: (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 3 each include a portion corresponding to the electrode and a lead portion that leads the electrode to the outside of the substrate.
a, 3b, 3c, 3d, 3e, 3f, a portion surrounded by the "day" shaped display portion, a portion corresponding to the horizontal bar display portion in the middle, and a lead portion leading this out of the board. (b) The electrode substrate B includes six display parts excluding the horizontal bar display part in the middle among the "Sun" shaped display parts and the seventh electrode part 3g. A first pattern electrode corresponding to a portion of the electrode 3g excluding the central horizontal bar display portion and a second pattern electrode corresponding to a portion excluding the first pattern electrode are formed. We provide liquid crystal display panels that The liquid crystal display panel and driving method 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.
The surface in contact with the liquid crystal molecules is coated with a vertical alignment film (FS150 film manufactured by Dainippon Ink). FS150 membrane is
The electrode substrate is immersed in an aqueous solution of 0.03% by weight of FS150, then dried and baked 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. Figure 3-1 is a diagram showing the pattern electrodes on the front electrode board, and Figure 3-2 is a diagram showing the pattern electrodes on the back electrode board.The 7-segment numerical display is the solid line and dotted line shown in Figure 3-1. a surrounded by,
It is displayed in 7 segments: b, c, 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, 3.
It is divided into seven pattern electrodes: e, 3f, and 3g. Segments a, b, c, d, e, f, g
The electrodes in the shaded area in the figure surrounded by are included in the pattern electrode 3g. The electrodes on the back electrode board are 6 segments a, b, c, d, e, f on the front electrode board, pattern electrodes corresponding to the part of the pattern electrode 3g excluding segment g, and 2 pattern electrodes in the other parts. It is divided. Therefore, in the patterned electrode described in this embodiment, the number of electrode divisions is small, and the patterned electrode 3g includes the shaded area shown in FIG. 3-1, so that 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 an n-digit number, 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. The electrodes on the back electrode board only need to have a common pattern electrode for each digit.Therefore, even if the number of digits increases, the electrodes on the back electrode board can be divided into two electrode patterns. The number of output drive circuits when the number is displayed 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 electrode 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 segment g by the electric signal applied to the pattern electrode and the electric signal applied to the pattern electrode 3g, but when the display is selected, the same electric signal S2 is applied. Therefore, no voltage is applied and therefore,
On the other hand, when the display is not selected, a voltage waveform G is applied by 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, the display will not be colored. . The part where the pattern electrode and the pattern electrode 3g face each other is the lead part of the segment g, and the part where the pattern electrode and the pattern electrode 3g face each other is the lead part of the segment g.
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. Pattern electrodes 3a, 3 on the front electrode board
An electric signal S1 is applied to each of b, 3c, 3d, 3e, and 3f when display is selected, and an electric signal S4 is applied when display is not selected. The electrical signal S4 is different from the electrical signals S1 and S2. When such an electric signal is applied, segments a, b, c, d, e, f have the electric signal applied to the pattern electrodes and the pattern electrodes 3a,
A voltage is applied by the electric signal applied to each of 3b, 3c, 3d, 3e, and 3f, but when the display is selected, since the same electric signal S1 is used, no voltage is applied, and therefore, although it is colored, , On the other hand, when display is not selected, different electrical signals S1 and S4 are displayed.
A voltage waveform H is applied, 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 parts of the pattern electrodes and the pattern electrodes 3a, 3b, 3c, 3d, 3e, and 3f are the lead parts of each of the segments a, b, c, d, e, and f, but the electrical signals S2 and S1 Alternatively, the voltage waveform can be determined by electric signal S3.
HL is applied, but if the effective voltage of this voltage waveform HL is equal to or higher than the threshold voltage, no coloring occurs. that's all,
Although the driving method of the present invention has been explained, only the display selection segment is colored, the others are not colored, and
The lead portion of each segment serves as a background, and therefore, a positive display in which display segments with a white background are colored can be realized. Numbers 0 to 1 in Table 1
The electrical signals applied to each pattern electrode when displaying 9 are shown.

[Table] The following describes the case where the electrical signals S1, S2, S3, and S4 used as the embodiment (1) of the driving method of the present invention described above are rectangular wave signals with the same frequency, the same peak value, and the same duty, but with different phases. state A DC rectangular wave signal with a frequency, peak value V ₁ , and duty 1/2 is used as the electrical signal S1, and the electrical signal S2 has a phase of Θ ₁ (π<Θ ₁ <
π, Θ ₁ ≠ 0), and the electrical signal S3 is out of phase with the electrical signal S1 by Θ ₂ (−π<Θ ₂ <π, Θ ₂ ≠
0, Θ ₁ ), and the phase of the electrical signal S4 is Θ ₃ (−π<Θ ₃ <π, Θ ₃ ≠0,
Θ ₁ ). These four types of electrical signals apply to the voltage waveforms G and H applied to the segment when display is not selected, and the voltage waveforms GL and HL applied to the lead portion of the segment.
This is explained below. As mentioned above, the voltage waveform G is generated by the electric signal S2 and the electric signal S3 as |Θ ₁ −Θ ₂
When |π, duty {2π−|Θ ₁ −Θ ₂
It is an AC rectangular waveform with ||}/π, peak value V ₁ , and frequency, and when |Θ ₁ −Θ ₂ |π, the duty |
It is an AC rectangular waveform of Θ ₁ −Θ ₂ |/π, peak value V ₁ frequency. The voltage waveform GL has a duty due to the electric signal S1 and the electric signal S2 |Θ ₁ |/π, a peak value V ₁ ,
Duty due to AC rectangular waveform of frequency or electric signal S1 and electric signal S3 |Θ ₂ |/π wave height value V ₁ ,
It is an AC rectangular waveform of frequency. The voltage waveform H is an AC rectangular waveform with a duty |Θ ₂ |/π, a peak value V ₁ , and a frequency due to the electric signals S1 and S4, and the voltage waveform HL has a duty |Θ ₁ due to the electric signals S2 and S1.
|/π, peak value V ₁ , frequency AC rectangular waveform or electric signal S2 and electric signal S4 |Θ ₁
−Θ ₃ | When π, duty {2π− | Θ ₁ −Θ ₃
It is an AC rectangular waveform with |｝/π, peak value V ₁ , and frequency, and when |Θ ₁ −Θ ₃ |π, the duty is |Θ ₁
It is an AC rectangular waveform with −Θ ₃ |/π, peak value V ₁ , and frequency. Duty｜Θ｜/π, peak value V ₁ ,
The effective voltage of an AC rectangular waveform of frequency is √|
It is expressed as |/π・V ₁ , but the above voltage waveform G,
Θ ₁ , Θ ₂ , Θ ₃ , and V ₁ are determined so that the effective voltages of H, GL, and HL are equal to or higher than the threshold voltage value. Θ ₂ and Θ ₃ may be the same. Two specific examples using specific numerical values will be described with reference to the drawings regarding the above-mentioned embodiment (1). As a first specific example, a voltage waveform shown in FIG. 4 is applied to each pattern electrode. Electrical signal S1 is 100Hz, duty 1/2,
It is a DC rectangular wave with a peak value V ₁ , and the electrical signal S2 is delayed in phase by 2/3π with respect to the electrical signal S1.
(Θ ₁ = -2/3・π) Electrical signal S3 is electrical signal S1
The phase is ahead by 2/3π. (Θ ₂ = Θ ₃ = 2/3
π, electrical signal S4 is the same as electrical signal S3). The voltage waveforms applied to each segment and the lead portion of each segment by these three types of electrical signals are G, H, GL-1, GL-2, HL-1, HL-2,
I (pattern electrode, side is shown as + potential). indicates that the voltage applied to the segment at the time of display selection is 0. G indicates the voltage waveform applied to segment g when display is not selected, and H indicates segments a, b, c, d, e,
It shows a voltage waveform applied to f when display is not selected. GL-1 and GL-2 indicate the voltage waveforms of the lead portions of segment g, and HL-1 and HL-2 indicate the voltage waveforms of the lead portions of segments a, b, c, d, e, and f. An AC rectangular wave with a duty of 2/3 is applied to each part other than the segments when these displays are selected, and the effective voltage value of this rectangular wave is √
V ₁ is determined so that 2/3 V ₁ is greater than or equal to the threshold voltage value of the liquid crystal display panel used. Next, as another specific example, a voltage waveform shown in FIG. 5 is applied to each pattern electrode. Electrical signal S1 is 100Hz duty 1/2,
The electrical signal S2 is a DC rectangular wave with a peak value V ₁ , and the phase of the electrical signal S2 is delayed by π/2 (Θ ₁ =-π/2) with respect to the electrical signal S1.
₂ , the electrical signal S
4 has an opposite phase (Θ ₃ =π) with respect to the electric signal S1. The voltage waveforms applied to each segment and the lead portion of each segment by these four types of electrical signals are waveforms represented by G, H, GL, HL, and I. (In the figure, the pattern electrode side is shown as + potential). indicates that the voltage applied to the segment at the time of display selection is 0. G indicates a voltage waveform applied to segment g when display is not selected, and H indicates a voltage waveform applied to segments a, b, c, d, e, and f when display is not selected. on the other hand,
GL indicates the voltage waveform of the lead portion of segment g, and HL indicates the voltage waveform of the lead portion of segments a, b, c, d, e, f. GL and HL
is an AC rectangular wave with a duty of 1/2 and a peak value of V ₁ , and the effective voltage of this AC rectangular wave is V ₁ /√2, but it is sufficient to make this value equal to or higher than the threshold voltage of the liquid crystal display panel used. . Since a voltage is always applied to this lead portion, it is unrelated to the response of the liquid crystal display panel, and therefore, V ₁ /√2 may be set as the threshold voltage. On the other hand, when display is not selected, segments a, b, c, d, e, f, and g have a duty of 1,
Since an AC rectangular wave with a peak value of V ₁ is applied, no coloring occurs. I mentioned two specific examples above, but
In the former example, an effective voltage √23V ₁ is applied to the lead portion and the segment portion that is not displayed, whereas in the latter example, an effective voltage V ₁ /√2 is applied to the liquid crystal molecules in the lead portion, and the segment An effective voltage V ₁ is applied to the part. In contrast to the threshold voltage V _H of the liquid crystal display panel, in the former example, V ₁
√32V _H , in the latter example V ₁ √2V _H
Therefore, the former specific example driving method can be driven at a lower voltage. However, when considering the response time, the voltage applied to the non-displayed segment portions is higher in the latter specific driving method, so the latter specific driving method is superior in terms of response characteristics. Therefore, it is only necessary to select one of the two driving methods depending on the purpose of use. Next, electric signals S1 and S used as Example (2)
2, S3, and S4, the case where the frequencies of at least S1 and S2 differ by an integral multiple will be explained using a specific example. FIG. 6 shows voltage waveforms for explaining the embodiment (2), where the electric signal S1 is a DC rectangular wave with a duty of 1/2, a frequency _{of 1} = 200Hz, and a peak value of _V1 , and the electric signal S2 is For the electric signal S1,
Frequency ₂ is a DC rectangular wave of 1/2 the magnitude, that is, 100Hz. The electric signal S3 and the electric signal S4 are
The electrical signals 2 and 1 have opposite phases to each other. The voltage waveforms applied to each segment and the lead portion of each segment by these four types of electrical signals are waveforms represented by G, H, GL, HL, and I (in the figure, the pattern electrode side is + voltage (electrical signal (S3 and S4 may be the same) For example, it goes without saying that the peak value V ₁ may be changed, or the shape of the signal waveform may be changed. By using a liquid crystal display panel and using the driving method of the present invention, a positive display liquid crystal display device with a small number of driving 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 embodiment of the present invention, and shows pattern electrodes of a liquid crystal display panel used in an embodiment of the present invention. 1 is a pattern electrode diagram of a front electrode substrate; 2 is a pattern electrode diagram of the back electrode substrate. FIGS. 4 and 5 are embodiments (1) of the driving method of the present invention.
Schematic diagram of electrical signals used to explain the 6th
The figure shows a schematic diagram of electrical signals used to explain embodiment (2) of the driving method of the present invention. Figures 1 and 3
In the figure, a, b, c, d, e, f, g are segment parts, 4, 9 are glass substrates, 5-1, 5-2, 8 are electrode patterns, 6, 7 are vertical alignment films, 10 is a reflection Boards 11-1 and 11-2 are liquid crystal molecules (schematic orientation diagram), S1, S2, and S in FIGS. 4, 5, and 6.
3, S4 is an electric signal applied to the pattern electrode,
G and H are voltage waveforms applied to segments that are not displayed, GL and HL are voltage waveforms applied to the lead portions of segments, and voltage waveforms are applied to display segments.

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 "Japanese character", (a) the electrode substrate A has six display parts, excluding the horizontal bar display part in the middle, of the display area in the shape of a Japanese character "Sun"; 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 includes six display parts of the "Sun"-shaped display part excluding the middle horizontal bar display part, and the seventh electrode 3g. A liquid crystal characterized in that a first pattern electrode corresponding to a portion excluding the central horizontal bar display portion and a second pattern electrode corresponding to a portion excluding the first pattern electrode are formed. display panel.