JP2003029242A - Liquid crystal module and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower the power consumption of a liquid crystal device and to obtain display having fancy appearance. SOLUTION: In the liquid crystal module 40, a first liquid crystal panel 1B and a second liquid crystal panel 1A having operating modes different from each other are provided on a circuit board 16 in a row, a driving device 15 is provided so as to be able to drive the respective liquid crystal panels independently and the minimum distance t between the electrode patterns of the two liquid crystal panels is <=20 mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal module having a plurality of liquid crystal panels having different operation modes and a liquid crystal display device having the same.

[0002]

2. Description of the Related Art There is known a technique for forming a large-sized display device in which the display surfaces of a plurality of liquid crystal display devices are arranged in parallel, as in Japanese Patent Laid-Open No. 9-211410 (conventional example 1). This is because a display having a size larger than the limited display area of one liquid crystal display device is performed.

Further, in Japanese Patent Laid-Open No. 2000-227586,
By stacking multiple liquid crystal panels that exhibit different operation modes,
A liquid crystal display device capable of displaying complicated display information is shown. In that example, it is shown that a polymer-dispersed liquid crystal display device and a bistable polymer-containing cholesteric liquid crystal display device can be used to provide a bright and decorative display without using any polarizing plate. (Conventional example 2).

Generally, a ferroelectric liquid crystal display device having a memory type operation mode and a chiral nematic liquid crystal display device are known (conventional example 3). The feature is that the display can be held even when no voltage is applied. But,
These display elements have not been widely used as a general-purpose liquid crystal display device because their driving waveforms are more complicated than those of TN liquid crystals and STN liquid crystals and their driving voltages are large.

[0005]

Liquid crystal display devices are widely used as display devices for portable devices, public display devices, display devices for personal computers, and display devices for consumer and industrial equipment. However, depending on the nature and content of the display information to be displayed, rewriting of the display is extremely small and rewriting is frequently performed. In that case, when the performance of the entire display device is evaluated, there is a problem that the power consumption required for rewriting the display is large.

Conventional Example 1 is intended to display a large screen, and no technical idea of reducing power consumption is found. In addition, in the liquid crystal display device of the second conventional example, the display surfaces of the two liquid crystal panels that are stacked are the same even when a part of the display information is rewritten on one liquid crystal panel or the same display information is held. Since they are formed in combination, it is basically necessary to drive both liquid crystal panels. Therefore, it was not possible to achieve a comprehensive reduction in power consumption.

Further, the liquid crystal display device of Conventional Example 3 has an advantage that power consumption is very small when no voltage is applied. However, when rewriting the display or frequently updating the display, it is necessary to apply a high voltage pulse, and power consumption is required accordingly.

Usually, most of the power consumption of a liquid crystal display device is
It is consumed by the driving circuit and the light source, and the power consumption by the liquid crystal layer itself is relatively small. If the power consumption required for driving the power-saving liquid crystal display device can be suppressed, the power consumption can be further reduced.

In this case, it is necessary to optimize the display mode and drive according to the content of the display information required for the liquid crystal display device. Generally, such as TN liquid crystal and STN liquid crystal,
Line-sequential driving is performed on the matrix electrode group.
Also, in the case of the segment type electrode structure, the multiplex drive is performed.

The present invention intends to provide a plurality of pieces of display information having different rewriting frequencies, which are difficult in the conventional example, as an efficient and good-looking display. For example, the present invention provides a preferable liquid crystal display device when it is attempted to display display information that changes with time and display information that is relatively unchanged on the same display screen.

An object of the present invention is to improve the overall performance of a liquid crystal panel and a liquid crystal display device, reduce the power consumption of the entire device, and to obtain a liquid crystal display device in which a liquid crystal module can be easily assembled and has high productivity. That is.
Further, the present invention provides a new use method by configuring a liquid crystal display device using a liquid crystal panel that is always driven for displaying and a liquid crystal panel having a memory type operation mode.

[0012]

That is, the first aspect of the present invention is the first aspect in which a liquid crystal layer capable of stably holding only one optical state in the absence of a voltage is sandwiched between a pair of substrates with electrodes. And a second liquid crystal panel in which a liquid crystal layer capable of stably holding two or more optical states in the absence of applied voltage is sandwiched between a pair of substrates with electrodes. Provided is a liquid crystal module in which surfaces are arranged so that they can be seen at the same time.

Aspect 2 has a first liquid crystal panel and a second liquid crystal panel.
Mode 1 in which the liquid crystal panel of 1 is mounted on the same circuit board
The liquid crystal module according to 1. is provided.

In the third aspect, the minimum distance between the display pattern portion that can be controlled by the voltage of the first liquid crystal panel and the display pattern portion that can be controlled by the voltage of the second liquid crystal panel is 20.
The liquid crystal module according to aspect 1 or 2 having a size within mm is provided.

Aspect 4 is that the first liquid crystal panel is the first
Liquid crystal layer, the first liquid crystal layer has a twist orientation of 30 to 300 °, and at least 1 is provided corresponding to the first liquid crystal layer.
Provided is a liquid crystal module according to aspect 1, 2 or 3 in which a plurality of polarizing plates are arranged.

The fifth aspect is the first, second, third or fourth aspect.
A liquid crystal display device comprising: the liquid crystal module and the driving device as described in 1), wherein the frequency of rewriting the display to the first liquid crystal layer is higher than the frequency of rewriting the display to the second liquid crystal layer.

Aspect 6 provides the liquid crystal display device according to Aspect 5, which is used in any of a measuring device, a portable device, a clock display device, and a data display device.

In the above liquid crystal panel, the first liquid crystal layer has a liquid crystal having a twist orientation of 30 to 300 ° (hereinafter, referred to as T).
It is called N-LC. ), And the second liquid crystal layer is a chiral nematic liquid crystal or a cholesteric liquid crystal (hereinafter, CL
-LC. ) Is preferable.

CL-LC may be either a polymer-containing type or a polymer-free type, but it is preferable to use the polymer-free type because the production is easy. Usually, it is prepared to have a helical pitch that selectively reflects visible light. Then, it is preferable to provide a light absorbing layer or a black layer that absorbs at least a part of visible light on the back-side substrate (substrate opposite to the observing side) of the second liquid crystal layer having a bistable optical state.

The boundary film used in the above liquid crystal panel is preferably formed by any method selected from a rubbing alignment method, a photo-alignment method, an oblique deposition method, a transfer alignment method and a non-alignment method. (See, eg, US Pat. No. 6,156,232 for prior art examples of alignment films).

The main boundary film for twisting the liquid crystal is preferably a rubbing-processed polymer thin film having a pretilt angle of 10 ° or less. The polyimide used in the TN liquid crystal can be used.

Further, in the present invention, as the non-alignment boundary film used for CL-LC, a liquid crystal layer such as a flattening film or an insulating film may be used in addition to the provision of a polymer film such as polyimide which has not been rubbed. The base film in contact with may be used as it is as a boundary film. Basically, any material can be used as long as it is a substrate surface constituent material usually used in a liquid crystal cell.

However, it is preferable to use a vertically oriented boundary film in order to secure a good brightness level. For example, a polymer film having a pretilt angle of 60 ° or more is preferable. It is particularly preferable to use a vertical alignment film. Alternatively, the surface of the base film can be used as it is without using the polymer film. However, the viewing angle tends to be rather limited.

Table 1 below shows combinations of boundary films that can be used for CL-LC. In the table, the boundary film is OC,
PL for the planar state, FC for the focal conic state,
The complete planar state exhibiting specular reflection is abbreviated as complete PL. O means bistability, and x means no bistability.

[0025]

[Table 1]

Usually, the alignment ability of the boundary films on the front substrate side and the back substrate side determines the orientation of the sandwiched liquid crystal layer. Since a plurality of liquid crystal panels are used in the present invention,
A boundary film that can be easily used in each liquid crystal panel and can obtain desired display characteristics can be adopted. Stable TN-LC is a normal orthogonal rubbing alignment film, and CL-LC is a non-alignment film made of a resin such as polyimide that is not rubbed.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION A "clock display" will be described as an example of a display including display information having different rewriting frequencies. When the present invention is used, the "second display" segment is displayed on the first liquid crystal panel, and the "hour display / minute display" segments are displayed on the second liquid crystal panel capable of stably holding two or more optical states. I do. The second liquid crystal panel has a so-called memory type operation mode.

As a specific mode, TN-LC can be used for the liquid crystal of the first liquid crystal panel. As the TN-LC, a TN liquid crystal with a transmission type of 90 ° twist, 240 °
Examples include STN liquid crystal having front and rear twist alignment, and TN liquid crystal having a 63 ° twist reflective structure. In addition to the CL-LC, there is a ferroelectric liquid crystal element as the liquid crystal used for the second liquid crystal panel.

A plurality of liquid crystal panels having different operation modes are provided in one liquid crystal module and combined with an external driving device to form a liquid crystal display device. Then, it provides a good-looking display and achieves low power consumption.

Next, the basic structure of the liquid crystal module of the present invention will be described. When arranging a plurality of liquid crystal panels in one liquid crystal module, it is preferable that the respective display surfaces cooperate to display related display information at the same time. It suffices to arrange a plurality of display screens so that both display screens can be sufficiently viewed within the visual field range of the user.

In FIG. 2, the first liquid crystal display device including the non-memory type liquid crystal is shown.
The liquid crystal panel 1B and the second liquid crystal panel 1A including the memory type liquid crystal are arranged in parallel in the plane of the circuit board 16 and are arranged so that their display surfaces face each other. At least both display surfaces are in contact with each other, and it is preferable to combine them so that they are one display surface in appearance.

It is necessary that both display surfaces are placed at positions where the user can see them at the same time. The display pattern on the liquid crystal display surface is visually recognized, and the layout is designed so that both display surfaces are included in the viewing angle at a readable distance. It is preferable to arrange the two liquid crystal panels so that one side is adjacent to the other side.

The four-digit display of "12 minutes 04 seconds" of the liquid crystal module 40 shown in FIG. 2 is a display of related numbers.
That is, certain display information is separated, and the plurality of liquid crystal panels share the display information. At this time, the second liquid crystal panel 1A displays a display with a low rewriting frequency, and the first liquid crystal panel 1B displays with a high rewriting frequency.

In the case of the liquid crystal module shown in FIG.
There is a boundary between "2" and "04", and the minimum distance t between the electrode patterns "2" and "0" is set within 20 mm.
The design is preferably made within 10 mm.

As described above, in the present invention, a predetermined display is performed by using a plurality of liquid crystal panels. On this occasion,
Since the cell gap of each liquid crystal panel having a different operation mode and the alignment state of the liquid crystal can be designed independently, manufacturing is easy. It is also preferable because the optimum operating conditions of each liquid crystal panel can be utilized. For example, in the electrode configuration, one liquid crystal module can be a segment electrode and the other can be a dot matrix electrode. The reverse is also possible, and it is also possible to combine them in each liquid crystal panel.
Further, the size of the two liquid crystal panels can be changed and the two liquid crystal panels can be arbitrarily combined in the plane of the substrate.

At this time, if the outer dimensions of the plurality of liquid crystal panels, the lead-out structure of the electrodes, and the terminal pitch of the electrodes are made substantially equal, the liquid crystal panels can be mounted on the circuit board and connected to wiring materials such as FPC. It is preferable because it becomes easy. Then, it is preferable that the display surfaces of the plurality of liquid crystal panels are closely aligned and observed as one display surface. Furthermore, it is preferable to install a protective plate or a protective film on the front side of both liquid crystal panels.

FIG. 3 shows a schematic sectional view of the liquid crystal module 50 of the present invention. The second liquid crystal panel 1A and the first liquid crystal panel 1B are assembled as if they were an integrated liquid crystal panel. In this configuration example, the twist angle of the TN-LC is about 63 °, only one polarizing plate 8 is provided on the front substrate 1 side, and the λ / 4 plate 10 and the boundary film 3B are further arranged.

A boundary film 4B and a reflective film 9 are arranged on the back substrate 2 side. Perimeter seals 5 are placed on the four sides of the substrate. With this configuration, it is possible to exhibit almost the same performance as a TN liquid crystal display device having a transmission type configuration with a 90 ° twist.

In CL-LC, the boundary film 3 is provided on the front substrate 1 side.
A, a boundary film 4A is provided on the back substrate 2 side, and a black layer 11 is coated on the back surface of the back substrate 2. Further, a protective plate or a protective film is arranged on the front surface side of the front substrate so as to cover the first liquid crystal panel 1B and the second liquid crystal panel A.

Usually, the cell gap of TN-LC is 3 to 1.
The thickness is set to 2 μm, preferably 5 to 8 μm. CL-LC
Has a cell gap of 2.5 to 6.0 μm, preferably 3 to
Set to 5 μm. In the case where a plurality of liquid crystal panels are mounted on a circuit board, it is preferable in terms of manufacturing to preassemble them as a substantially integrated liquid crystal panel and handle them as one liquid crystal panel. This is particularly advantageous when forming a very thin display element.

Below, the first liquid crystal panel, TN-LC,
The present invention will be described with reference to the case of using CL-LC for the second liquid crystal panel.

[0042]

EXAMPLES (Example 1) A first liquid crystal panel having a 90 ° twist orientation was manufactured as follows. Two substrates provided with a transparent conductive film (ITO) were prepared, and the transparent conductive film of each substrate was etched to have a shape corresponding to the second display, an electrode line interval, and the number of electrodes to form an electrode group. .

Next, an electrically insulating layer is formed on the transparent electrode,
Furthermore, polyimide (model number: LX-58) is formed on the electric insulation layer.
(Hitachi Chemical Co., Ltd.) polymer solution was applied and baked to form a polyimide film. Then, the upper and lower substrates were rubbed in one direction so that the polyimide films of the respective substrates were orthogonal to each other to form a horizontal alignment film having a film thickness of 300Å and a pretilt angle of about 2 °.

Spacers of resin beads having a diameter of 8 μm were scattered between the electrode facing surfaces of the two substrates with electrodes. After that, a peripheral sealing material made of an epoxy resin containing a minute amount of glass fiber having a diameter of about 8 μm was applied to the four sides of the substrate except for the portion to be the liquid crystal injection port. Then, two substrates with electrodes were attached to each other to prepare a liquid crystal cell.

Next, nematic liquid crystal (general-purpose TN liquid crystal can be used, for example, ZLI series manufactured by Merck) is injected into the liquid crystal cell by a vacuum injection method, and then the injection port is sealed with a photo-curing resin. 1 liquid crystal panel was formed. further,
The respective polarization axes were attached to the front and back of the substrate so that the rubbing alignment directions of the alignment films of the respective substrates coincided with each other. The light source was placed on the lower surface of the back substrate.

In the first liquid crystal panel, the 90 ° twist-aligned liquid crystal layers are aligned by the applied voltage, and the optical characteristics change accordingly. On / off operation is performed in combination with two polarizing plates provided on the outside. In this example, the display of the 10-second and 1-second digits and symbols indicating various states is TN-
Performed by LC. The driving was performed by a normal driving IC for TN liquid crystal.

Next, a second liquid crystal panel was manufactured. Two substrates with a transparent conductive film (ITO) were prepared. Etching was performed on each substrate so that the electrode shape, the electrode line interval, and the number of electrodes corresponded to the hour / minute display, and an electrode group was formed. Next, an insulating layer was formed on the electrode surface side of each substrate. Subsequently, a polyimide polymer solution was applied onto the insulating layer of each substrate and baked to form a polyimide film. The film thickness was about 600Å. The surface of this polyimide film was not subjected to rubbing orientation, and was left in the surface state after firing and used as a non-oriented film.

Next, a second liquid crystal panel was manufactured in the same manner as the first liquid crystal panel. At this time, the spacer has a diameter of 4
A glass fiber with a diameter of 4 μm was used in the seal. For CL-LC, T _c = 8
7 ° C, Δn = 0.231, Δε = 16.5, viscosity η =
The chiral agent 5.1 shown in Chemical formula 1 was added to 84.7 parts of a nematic liquid crystal having a specific resistance of 2 × 10 ¹¹ Ω · cm and a specific resistance of 2 × 10 ¹¹ Ω · cm.
Liquid crystal P in which 5.1 parts of the chiral agent shown in Chemical formula 2 and 5.1 parts of the chiral agent shown in Chemical formula 3 were dissolved and mixed. The liquid crystal P had a helical pitch of about 0.34 μm.

[0049]

[Chemical 1]

[0050]

[Chemical 2]

[0051]

[Chemical 3]

After the liquid crystal P was injected into the liquid crystal cell by the vacuum injection method, the injection port was sealed with a photo-curing resin. The injected liquid crystal P was in direct contact with the polyimide film to form a predetermined alignment state.
A black paint for matting was provided in advance as a coloring layer on the back substrate surface of the second liquid crystal panel.

CL-LC of the second liquid crystal panel has the following optical states. P, which is one of the bistable optical states
In the L state, the average direction of the orientation axis (helical axis) of the twist structure having a constant repeating pitch p is substantially perpendicular to the electrode substrate. Liquid crystal pitch p and average refractive index n
Selective reflection occurs at a specific wavelength λ determined by _AVG (λ = n _AVG · p).

On the other hand, in the FC state, the helical axes are oriented in different directions with respect to the electrode substrate surface, and a part of the incident light is scattered but most of the light is transmitted. Therefore, the color of the colored layer provided on the back side is observed from the front side.

Then, on the external electrodes of the second liquid crystal panel,
When a 30 V bipolar rectangular wave pulse with a pulse width of 500 ms was applied and then the voltage was cut off, all the pixel portions were in the PL state and green light was reflected. Next, 20V
When the voltage was cut off after applying the bipolar rectangular wave pulse of No. 3, weak scattering due to the FC state was exhibited, the background color black was visually recognized from the front side, and all the pixel portions were black.

After that, even if the voltage applied to change the optical state is cut off, the CL-LC of the second liquid crystal panel is cut off.
The stable alignment state was maintained, and a sufficient contrast ratio that could be visually recognized as a display was secured.

In this way, the "year, month, day, hour display / minute display" portion of the calendar is displayed on the second liquid crystal panel 1A.
Then, "second display" was performed on the first liquid crystal panel 1B, and the clock display could be achieved by the liquid crystal module 30 by using both (see FIG. 1). 2001, June 13, 12:59
Minutes, 30 seconds, and other symbols and status indications were configured to be displayed on one screen, and driving was performed by connecting driving devices 15A and 15B to the respective liquid crystal panels.

As a display mode, the pixels of CL-LC are displayed in green which is the selected color, and the pixels of TN-LC are displayed in black and white. At this time, the display surfaces of the two liquid crystal panels were brought into contact with each other and mounted as one liquid crystal module on the printed wiring board. It is preferable to arrange such that the minimum distance t between the segments of both liquid crystal panels is within 20 mm in a plane horizontal to the substrate surface.

Peripheral seals are provided on the mating sides of the two liquid crystal panels. The peripheral seals are thinned and the space between the peripheral seals and the electrode pattern is narrowed.
The minimum distance of the segment electrode pattern between two liquid crystal panels is shortened. In this example, it is set to 10 mm, but it can be set within a range that does not impair the quality of desired display information, and can be selected from a range of 8 to 20 mm, for example.

In this way, according to the present invention, when viewed as the entire display device, the power consumption can be significantly reduced as compared with the case where each liquid crystal panel is used alone.

Example 2 The resin orientation material of Example 1 was changed to a material having a soft surface hardness. Specifically, a liquid crystal panel of CL-LC was manufactured using a polyimide resin solution RN-1266 or RN-1286 manufactured by Nissan Chemical Industries, Ltd. The surface hardness of the polyimide film after baking was "B" and "3B" by the pencil test method (JIS.
K 5400, JIS S 6006, JIS R 6
252). In this example, a good display could be obtained without causing a burn-in phenomenon on the second liquid crystal panel. The technique using this specific alignment film is disclosed by the present inventors in Japanese Patent Application No. 2000-402045.

Example 3 A liquid crystal panel module 60 was used as the display device for the oscilloscope shown in FIG. The measured waveform is displayed on the first liquid crystal panel 1B, and the variable data such as the data of the measured object and the date is displayed on the second liquid crystal panel 1A.
It is configured to display in. Since the first liquid crystal panel 1B is a 480 × 640 dot matrix system and uses STN liquid crystal with a twist angle of 240 °, a display with a high contrast ratio was obtained.

In addition, among the measured values, data that is immediately saved and referred to many times is CL-LC arranged on the left side of the drawing.
The display screen of the second liquid crystal panel 1 </ b> A having the above is moved to directly store the memory on the display screen. The processing of the display data may be controlled by the input means, the driving device and the microcontroller. In this case, even if the power of the oscilloscope was turned off, the data was saved and displayed in a part of the display, which was extremely convenient for use.

Example 4 A liquid crystal module 70 was used as a display device of a mobile device (see FIG. 5). The second liquid crystal panel 1A is configured to display invariable data within a predetermined time, and the first liquid crystal panel 1B is configured to display display information that is frequently rewritten. In this example, the operating conditions of both liquid crystal panels are adjusted, and one driving device 15 is commonly used to drive and design for display.

FIG. 6 shows a schematic sectional view of this example. The two liquid crystal panels 1A and 1B are mounted on the common circuit board 16. Further, a common cover sheet 12 was provided on the front surface side. Further, in this example, the drive device 15 is also designed to be mounted on the circuit board 16. In this example, t was 8 mm.

[0066]

According to the present invention, low power consumption can be achieved while performing a predetermined display as one liquid crystal module and one liquid crystal display device when displaying various display information. Further, it is possible to provide a liquid crystal module and a liquid crystal display device which are easy to manufacture and have good productivity.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a state in which a clock is displayed on a liquid crystal display device of the present invention.

FIG. 2 is a perspective view of a liquid crystal module of the present invention.

FIG. 3 is a schematic cross-sectional view of a liquid crystal module of the present invention.

FIG. 4 is a schematic diagram showing a display when the liquid crystal display device of the present invention is used in a measuring instrument.

FIG. 5 is a schematic view showing a display when the liquid crystal display device of the present invention is used for display of a portable electronic device.

6 is a schematic cross-sectional view of the example of FIG.

[Explanation of symbols]

1: Front side substrate 2: Back side substrate 1A: second liquid crystal panel 1B: first liquid crystal panel 3A, 3B, 4A, 4B: Boundary layer 5: Peripheral seal 6: First liquid crystal layer (non-memory liquid crystal layer) 7: Second liquid crystal layer (memory type liquid crystal layer) 30, 40, 50, 60, 70: Liquid crystal module

Continued front page    (72) Inventor Noriko Suehiro             1150 Hazawa-machi, Kanagawa-ku, Yokohama-shi, Kanagawa             Asahi Glass Co., Ltd. (72) Inventor Toshihiko Suzuki             1150 Hazawa-machi, Kanagawa-ku, Yokohama-shi, Kanagawa             Asahi Glass Co., Ltd. F term (reference) 2H089 HA33 HA40 JA10 TA04 TA07                       TA15                 2H092 GA20 GA24 PA02 PA06

Claims (6)

[Claims] 1. A first liquid crystal panel in which a liquid crystal layer capable of stably holding only one optical state is sandwiched between a pair of substrates with electrodes, and a pair of substrates with electrodes, A second liquid crystal layer sandwiching a liquid crystal layer that can stably maintain two or more optical states when no voltage is applied.
The liquid crystal module and the liquid crystal panel are arranged so that the display surfaces of the respective liquid crystal panels can be seen at the same time. 2. The liquid crystal module according to claim 1, wherein the first liquid crystal panel and the second liquid crystal panel are mounted on the same circuit board. 3. The minimum distance between the display pattern portion that can be controlled by the voltage of the first liquid crystal panel and the display pattern portion that can be controlled by the voltage of the second liquid crystal panel is within 20 mm. The described liquid crystal module. 4. The first liquid crystal panel comprises a first liquid crystal layer,
The first liquid crystal layer has a twist orientation of 30 to 300 °,
The liquid crystal module according to claim 1, 2 or 3, wherein at least one polarizing plate is arranged corresponding to the first liquid crystal layer. 5. The liquid crystal module and the driving device according to claim 1, 2, 3 or 4, and the display rewriting frequency in the first liquid crystal panel is higher than the display rewriting frequency in the second liquid crystal panel. Many liquid crystal display devices. 6. The liquid crystal display device according to claim 5, which is used in any one of a measuring device, a mobile device, a clock display device, and a data display device.