JPH0760230B2 - Liquid crystal display - Google Patents

Description

The present invention relates to a guest-host type liquid crystal display device using a ferroelectric liquid crystal.

[Prior Art] In recent years, research and development of liquid crystal display devices using ferroelectric liquid crystals have been conducted in various places. One of the display principles of a liquid crystal display device using a ferroelectric liquid crystal is one using a guest-host type display mode.

FIG. 4 shows the display principle of a conventional guest-host type liquid crystal display device using a ferroelectric liquid crystal.

In the figure, 30 is a liquid crystal panel in which a ferroelectric liquid crystal 34 and a dichroic dye 35 are filled between transparent substrates so that their molecular axes are parallel to each other, and 37 is a deflecting plate.

FIG. 6A shows a dark state in which the light transmitted through the liquid crystal panel 30 and the deflection plate 37 becomes dark. LCD panel 30
Applying a predetermined electric field in one direction perpendicular to the
The molecular axes of 34 and the dichroic dye 35 are aligned at a predetermined angle with respect to the deflection axis of the deflection plate 37. At this time, only the light components in the direction perpendicular to the molecular axes of the ferroelectric liquid crystal 34 and the dichroic dye 35 are transmitted through the liquid crystal panel 30. Since the light component transmitted through the liquid crystal panel 30 has a predetermined angle with respect to the deflection axis of the deflection plate 37, only the light component parallel to the deflection axis of the deflection plate 37 passes through the deflection plate 37. Therefore, a considerable amount of light is attenuated by the deflection plate 37, and the display state becomes a dark state.

FIG. 2B shows a bright state in which the light transmitted through the liquid crystal panel 30 and the deflection plate 37 is brighter than the dark state.

A predetermined electric field is applied to the liquid crystal panel 30 in a direction opposite to that in the dark state so that the molecular axes of the ferroelectric liquid crystal 34 and the dichroic dye 35 are perpendicular to the deflection axis of the deflection plate 37. Align. At this time, the ferroelectric liquid crystal 34 and the dichroic dye 35
Only the light component in the direction perpendicular to the molecular axis of is transmitted through the liquid crystal panel 30. Since the light component transmitted through the liquid crystal panel 30 is parallel to the deflection axis of the deflection plate 37, the light transmitted through the liquid crystal panel 30 passes through the deflection plate 37 without being attenuated. Therefore, the display state becomes brighter than the dark state and becomes the bright state.

Conventionally, the molecular axes of the ferroelectric liquid crystal 34 and the dichroic dye 35 are rotated by reversing the direction of the electric field applied to the liquid crystal panel as described above, and the ferroelectric liquid crystal 34 at this time is rotated.
Further, the angle between the molecular axis of the dichroic dye 35 and the deflection axis of the deflection plate 37 is appropriately selected to control the brightness and darkness for display.

[Problems to be Solved] The molecular axes of the ferroelectric liquid crystal 34 and the dichroic dye 35 in the dark state (Fig. 4 (a)) and the ferroelectricity in the bright state (Fig. 4 (b)) The angle formed by the molecular axes of the liquid crystal 34 and the dichroic dye 35 is
Generally called a switching angle. This switching angle differs depending on the type of the ferroelectric liquid crystal, but in a practical material having a lower limit of 0 ° C. or less, the maximum is about 60 °.

Therefore, in the above conventional example, the ferroelectric liquid crystal 34
And the angle formed by the molecular axis of the dichroic dye 35 and the deflection axis of the deflection plate 37 is about 60 degrees at the maximum, and the light transmitted through the liquid crystal panel 30 cannot be completely blocked by the deflection plate 37. I could not get the ideal dark state. Therefore, the contrast was poor, and a liquid crystal panel having excellent display quality could not be obtained.

The present invention has been made to solve the above conventional problems,
An object of the present invention is to provide a liquid crystal display device having high contrast and excellent display quality, particularly a matrix type liquid crystal display device.

[Means for Solving the Problems] A liquid crystal display device according to the present invention includes a pair of first counter substrates, a pair of first electrodes having a matrix structure formed inside the pair of first counter substrates, and the pair of first counter substrates. And a pair of first ferroelectric liquid crystals filled between the first counter substrates of
A first dichroic dye filled between the opposed substrates, and formed so that the molecular axis of the first ferroelectric liquid crystal and the molecular axis of the first dichroic dye are parallel to each other. A first liquid crystal panel, a pair of second counter substrates, and a pair of second electrodes having a matrix structure formed inside the pair of second counter substrates,
A second ferroelectric liquid crystal filled between the pair of second counter substrates and a second ferroelectric liquid crystal filled between the pair of second counter substrates.
A second dichroic dye, which is formed so that the molecular axis of the second ferroelectric liquid crystal and the molecular axis of the second dichroic dye are parallel to each other, and is overlapped with the first liquid crystal panel. 2 liquid crystal panel, and in the bright state of transmitting or reflecting light, the molecular axes of the first ferroelectric liquid crystal and the first dichroic dye and the molecular axes of the second ferroelectric liquid crystal and the second dichroic dye. So that they are parallel to each other, the molecular axes of the first ferroelectric liquid crystal and the first dichroic dye and the second ferroelectric liquid crystal and the second dichroic dye are in a dark state where light is not transmitted or reflected. An electric field applying means for applying a predetermined electric field to the first electrode and the second electrode such that the molecular axes of the functional dye are substantially orthogonal to each other, and the one first electrode and the one second electrode The electrodes are commonly connected, and the other first electrode and the other second electrode are commonly used. Characterized in that the connection.

[Embodiment] An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 10 is a panel unit, which is a liquid crystal panel of two guest-host type using ferroelectric liquid crystal.
It is composed of 10A and 10B. Each of the liquid crystal panels 10A and 10B has a transparent substrate 11a made of glass or the like.
1b and 11c, 11d, transparent electrodes 12a, 12b and 12c, 12d,
Alignment layers 13a, 13b and 13c, 13d, ferroelectric liquid crystal 14a and
14b, dichroic dyes 15a and 15b whose molecular axes are parallel to the molecular axes of the ferroelectric liquid crystals 14a and 14b, and sealing members 16a and 16b.
The ferroelectric liquid crystals 14a and 14b and the dichroic dyes 15a and 15b are in a homogeneous alignment state. 20 is an electric field applying means, each of the transparent electrodes 12a, 12b and 12c, 1
Ferroelectric liquid crystal 14 of liquid crystal panels 10A and 10B through 2d
An electric field is applied to a and 14b.

FIG. 2 shows the principle of displaying light and dark with the above configuration.

FIG. 7A shows a bright state in which the light transmitted through the liquid crystal panels 10A and 10B becomes bright. In this state, when an electric field is applied to the respective liquid crystal panels 10A and 10B in a predetermined direction, the ferroelectric liquid crystal 1 of the liquid crystal panel 10A is
The molecular axes of 4a and the dichroic dye 15a are parallel to the molecular axes of the ferroelectric liquid crystal 14b and the dichroic dye 15b of the liquid crystal panel 10B. In the light transmitted through the liquid crystal panel 10A, only the light components in the direction perpendicular to the molecular axes of the ferroelectric liquid crystal 14a and the dichroic dye 15a pass through the liquid crystal panel 10A. Since the molecular axes of the ferroelectric liquid crystal 14b and the dichroic dye 15b of the liquid crystal panel 10B are perpendicular to the light component that has passed through the liquid crystal panel 10A, the light that has passed through the liquid crystal panel 10A is not attenuated. Penetrates 10B. In this way, an ideal bright state is obtained.

FIG. 2B shows a dark state in which the light transmitted through the liquid crystal panels 10A and 10B becomes dark. In this state, when an electric field is applied to the liquid crystal panels 10A and 10B in the opposite direction to that in the bright state, the ferroelectric liquid crystal 14a of the liquid crystal panel 10A and the molecular axes of the dichroic dye 15a and the liquid crystal The molecular axes of the ferroelectric liquid crystal 14b and the dichroic dye 15b of the panel 10B are substantially orthogonal to each other. In the light transmitted through the liquid crystal panel 10A, only the light components in the direction perpendicular to the molecular axes of the ferroelectric liquid crystal 14a and the dichroic dye 15a pass through the liquid crystal panel 10A.
Ferroelectric liquid crystal 14b and dichroic dye 15b of liquid crystal panel 10B
Since the molecular axis of is parallel to the light component transmitted through the liquid crystal panel 10A, almost all the light transmitted through the liquid crystal panel 10A is absorbed by the liquid crystal panel 10B. Therefore, almost no light passes through the liquid crystal panel 10B, and an ideal dark state can be obtained.

As described above, a liquid crystal display device having a sufficiently high contrast can be obtained without using a deflection plate.

In this example, the switching angles of the ferroelectric liquid crystal 14a and the dichroic dye 15a and the switching angles of the ferroelectric liquid crystal 14b and the dichroic dye 15b are both 45 degrees as shown in FIG. 2 (b). However, the sum of the switching angles of both is almost
It should be 90 degrees.

Ferroelectric liquid crystal 14a and dichroic dye 15a of liquid crystal panel 10A
Of the ferroelectric liquid crystal 14b and the dichroic dye 15b of the liquid crystal panel 10B, that is, the sum of the switching angles of the two is the maximum switching angle of the ferroelectric liquid crystal currently obtained. If it is 60 degrees or more, it is possible to obtain higher contrast than before. However, in order to obtain higher contrast, it is preferable that the angle is approximately 90 degrees as in this example.

In this example, as shown in FIG. 1, the transparent substrates 11a, 1a
Although a total of four 1b, 11c, and 11d are used, the transparent substrates 11b and 11c shown in the figure can be shared, and the panel unit 10 is configured with a total of three transparent substrates. May be.

The color of the dichroic dye can be any color, but if a black dichroic dye is used, white can be obtained in the bright state and black in the dark state, and a beautiful multicolor display can be obtained especially when combined with a color filter. it can.

FIG. 3 shows a connection state of the liquid crystal panels 10A and 10B shown in FIG. 1 when one transparent electrodes of the liquid crystal panels are commonly connected.

In FIG. 10A, the transparent electrode 12a of the liquid crystal panel 10A and the transparent electrode 12d of the liquid crystal panel 10B are connected in common, and the liquid crystal panel 10A is connected.
The transparent electrode 12b and the transparent electrode 12c of the liquid crystal panel 10B are commonly connected. Each transparent electrode is connected to a scan electrode drive circuit 20a and a signal electrode drive circuit 20b, which form an electric field applying means. This connection method is effective when the polarities of the spontaneous polarization of the liquid crystal panels 10A and 10B are the same.

In the same figure (b), the transparent electrode 12a of the liquid crystal panel 10A and the transparent electrode 12c of the liquid crystal panel 10B are connected in common, and the liquid crystal panel 10A
The transparent electrode 12b and the transparent electrode 12d of the liquid crystal panel 10B are commonly connected. Each transparent electrode is connected to a scan electrode drive circuit 20a and a signal electrode drive circuit 20b, which form an electric field applying means. This connection method is effective when the polarities of the spontaneous polarization of the liquid crystal panels 10A and 10B are opposite to each other.

By using the connection method as described above, it is possible to simplify the scan electrode drive circuit and the signal electrode drive circuit forming the electric field applying means.

In the above description, the case of performing display in the transmissive mode has been described, but the present invention is not limited to this, and can be applied to the case of performing display in the reflective mode.

[Effect] According to the present invention, it is possible to obtain a ferroelectric guest-host liquid crystal display device which can obtain an ideal bright state and a dark state without using a polarizing plate and has a sufficiently high contrast.

Further, by using a black dichroic dye, ideal white can be obtained in a bright state and ideal black can be obtained in a dark state, and a beautiful multicolor display can be obtained especially when combined with a color filter.

Further, since one electrode and the other electrode of the two liquid crystal panels of the matrix structure that are overlapped with each other are connected in common, the drive circuit and the like can be simplified.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention, FIG. 2 is an explanatory view showing the principle of the present invention, FIG. 3 is an explanatory view showing an example of a transparent electrode connecting method, and FIG. Is an explanatory view showing a conventional example. 10a, 10b ...... Liquid crystal panels 11a, 11b ...... Transparent substrates 12a to 12d ...... Transparent substrates 14a, 14b ...... Ferroelectric liquid crystal 15a, 15b ...... Dichroic dye 20 ...... Electric field applying means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A 61-159622 (JP, A) JP-A 62-266524 (JP, A) JP-A 2-29630 (JP, A) JP-A 64-- 52127 (JP, A)

Claims (1)

[Claims] 1. A pair of first counter substrates, and a pair of first first matrix substrates formed inside the pair of first counter substrates.
A first electrode filled between the electrode and the pair of first counter substrates.
A ferroelectric liquid crystal and a first dichroic dye filled between the pair of first counter substrates, and a molecular axis of the first ferroelectric liquid crystal and a molecule of the first dichroic dye. A first liquid crystal panel formed so that its axes are parallel to each other; a pair of second counter substrates; a pair of second electrodes having a matrix structure formed inside the pair of second counter substrates; A second ferroelectric liquid crystal filled between the second counter substrates, and a second dichroic dye filled between the pair of second counter substrates. A second liquid crystal panel formed so that its molecular axis and the molecular axis of the second dichroic dye are parallel to each other, and in the bright state of transmitting or reflecting light, 1. Ferroelectric liquid crystal and molecular axis of the first dichroic dye, the second ferroelectric liquid crystal and the second dichroic color In a dark state in which light is not transmitted or reflected, the molecular axes of the first ferroelectric liquid crystal and the first dichroic dye and the second ferroelectric liquid crystal and the second ferroelectric liquid crystal are aligned so that their molecular axes are parallel to each other. An electric field applying means for applying a predetermined electric field to the first electrode and the second electrode so that the molecular axes of the dichroic dye are substantially orthogonal to each other, and one of the first electrodes and one of the first electrodes are provided. A liquid crystal display device, wherein the second electrode is commonly connected, and the other first electrode and the other second electrode are commonly connected.