JP2001337314A - Liquid crystal display device and liquid crystal display device - Google Patents

Abstract

(57) Abstract: In a liquid crystal display device having a liquid crystal layer having a memory property, disturbance of liquid crystal alignment due to an external factor is restored. SOLUTION: In order to obtain a uniform alignment state between a pixel portion and a line portion, a distance (line width) between transparent electrodes 31 adjacent to each other in the same substrate surface 3 is a, and each of upper and lower substrates is formed. between the transparent electrodes 21 and 31 opposed between 2,3 thickness (pixel portion D) in sandwiched a liquid crystal layer d ([mu] m), the maximum effective voltage required to change the display V _{m ax,} transparent The maximum distance a (μm) between the electrodes is 4.0 ≦ a ≦ d · V / 1.
0 is satisfied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid crystal display device having a liquid crystal layer having a memory function and a liquid crystal display device using the same.

[0002]

2. Description of the Related Art At present, TN, STN and TFT liquid crystal display devices are widely used. These liquid crystal display elements always perform a predetermined drive to perform display. On the other hand, an antiferroelectric liquid crystal display element (hereinafter, referred to as AF-LCD) having a memory property operation, a cholesteric or chiral nematic liquid crystal display element (hereinafter, CL-L).
It is called CD. ) Is attracting attention, and its practical use is being studied.

The operation principle of AF-LCD is described in Proc. J
Apan Display 1989, 26 (198
9) is shown. The basic operation is as follows. The liquid crystal layer in the ferroelectric state is in the first state according to the polarity of the voltage applied from the outside.
And a second bookshelf state (-F). Then, a stable transition is made between the two states and the antiferroelectric state by applying a voltage, and a display corresponding to the three states is obtained.

In combination with a pair of polarizing plates, black is displayed in an antiferroelectric state and white is displayed in two ferroelectric states (+ F or -F). In the AF-LCD, when forming the liquid crystal cell, it is essential that the entire display surface has a uniform liquid crystal orientation. Usually, a high voltage is applied to the liquid crystal layer for about several seconds, and an energization process is performed to align the orientation of the liquid crystal layer.

The principle of operation of CL-LCD is US Pat.
15 and US Pat. No. 4,097,127. fundamentally,
A planar state in which a part of the incident light is selectively reflected (hereinafter referred to as PL
State. ) And a focal conic state that scatters incident light (hereinafter referred to as FC state).
It is stable in state and can transition between states. FIG. 1 shows an example of a cross-sectional structure of the element. Display is performed without using a polarizing plate.

[0006] After the CL-LCD is once applied with a voltage and placed in a predetermined display state, the display state is maintained even if the power is turned off. The AF-LCD requires the application of a holding voltage, but can similarly maintain the display state.

In the CL-LCD, in order to transfer the held display state to another display state, a predetermined voltage may be applied again. At this time, it is preferable to apply a voltage necessary for the next display after erasing the entire display surface once.

That is, from the viewpoint of use, it is preferable to completely erase the immediately preceding display and then rewrite it to a new display. Normally, the entire display surface is set to the FC state so that the liquid crystal display element is in a state of exhibiting a background color (dark color such as black). After that, it is general to draw a line drawing of a bright luminance level and display by drawing a desired pixel into the PL state.

[0009]

However, the display state may change from the FC state to the PL state due to an external force.
For example, there is a case where this change occurs when another object or a human hand directly touches the display surface of the CL-LCD. Alternatively, even when the display surface is not directly touched by the hand during use, an external force may be applied to the display surface when the liquid crystal display element is incorporated in the display device.

The liquid crystal region directly sandwiched between the row electrode (X electrode) and the column electrode (Y electrode) disposed opposite to each other can restore the display content changed by an external force by applying a predetermined voltage again. However, the alignment state of the liquid crystal region located between the lines where direct voltage cannot be applied cannot be arbitrarily controlled.

Therefore, when the line portion is brought into the PL state (operationally a reflection state) by an external force, a problem arises that it is difficult to restore the display change of the line portion. That is, even if writing is performed again to restore the display state of the liquid crystal region sandwiched between the electrodes, the line-to-line portion still retains the reflection state, so that the display contrast ratio is greatly reduced.

The same applies to the case where segment display is performed in the negative display mode in which bright display is performed on a dark background portion. When the line portion is brought into the PL state by an external force, the line portion is still in the reflection state even if writing is performed again.
Therefore, even a portion to be displayed black is reflected along the edge of the display electrode, making it difficult to visually recognize the original display.

FIG. 5 shows the display state. FIG. 5A shows a state in which an external force is applied and the liquid crystal alignment in the upper right segment is disturbed when “6” is displayed. Even if writing is performed again to display “6” after the application of the external force is stopped, the result is as shown in FIG. 5B, and the edge of the segment is colored and visually recognized. This hexagonal edge portion is an "interline portion" having no electrode, and the arrangement of the liquid crystal region is disturbed.

Next, the AF-LCD will be described.
FIG. 6 shows a cross-sectional structure of the AF-LCD 50. The front polarizer 9, the front substrate 3, the alignment film 8, the front electrode 31, the liquid crystal layer 5,
A peripheral seal 4, a back electrode 21, a back substrate 2, and a back polarizing plate 7 are provided. FIG. 7 is a graph showing the relationship between electric field application and transmitted light intensity in AF-LCD, and FIG.
One orientation state is shown.

In this AF-LCD, it is essential to perform in-plane alignment processing of the liquid crystal cell. Further, even after the alignment process is performed, the alignment may be disturbed due to external factors such as application of an external force and a change in temperature. In order to reorient the liquid crystal by the energization treatment, an element structure that stably and uniformly arranges the liquid crystal is required.

As described above, a problem peculiar to the memory type liquid crystal display element occurs, but it is conceivable to solve the problem using a black mask (hereinafter, referred to as BM). The BM is arranged in the line portion of the electrode substrate on the display surface side, and the line portion is always black so as not to be affected by the alignment state of the liquid crystal.

However, this technique requires a high-precision technique for positioning the BM and the electrode. Further, the brightness at the time of reflection decreases due to the decrease in the aperture ratio. In addition, a new process is required for forming the BM, which lowers productivity and further increases production cost.

An object of the present invention is to provide a liquid crystal display device and a liquid crystal display device having excellent functions without largely changing the conventional manufacturing method.

[0019]

According to a first aspect of the present invention, there is provided:
A liquid crystal layer is sandwiched between a front substrate having a front electrode and a rear substrate having a back electrode, and the liquid crystal layer has a plurality of display states, and the display state is shifted by a voltage applied between the electrodes. In a liquid crystal display element in which at least one of the display states is stably held, at least a part of the front electrode and the front substrate is transparent, and the front electrode or the back electrode has a plurality of Divided into electrode regions, the maximum distance a (μm) between adjacent electrode regions,
The thickness d (μm) of the liquid crystal layer is 1.0 · d ≦ a ≦ 4.0.
-Provide a liquid crystal display element characterized by satisfying the relational expression of d.

In a second aspect, a liquid crystal layer is sandwiched between a front substrate provided with a front electrode and a back substrate provided with a back electrode, and the liquid crystal layer has a plurality of display states. In a liquid crystal display element in which a display state is changed by a voltage applied to at least one of the display states and at least one of the display states is stably maintained, at least a part of the front side electrode and the front side substrate is transparent, and the front side electrode or The back electrode is divided into a plurality of electrode regions on each substrate surface, and a chiral nematic liquid crystal is used for a liquid crystal layer. The maximum distance a (μm) between adjacent electrode regions, the thickness d (μm) of the liquid crystal layer,
Maximum effective voltage V applied to front and back electrodes
_max (V) and is, 1.0 · d ≦ a ≦ d · V max / 1
A liquid crystal display device characterized by satisfying the relational expression of 0 is provided.

According to a third aspect, there is provided the liquid crystal display device according to the second aspect, wherein V _max is 48 V or less and 2.5 μm ≦ d ≦ 6.0 μm.

In a fourth aspect, at least a part of the front electrode is formed of a plurality of segment electrodes, and the back electrode is a single common electrode corresponding to all the segment electrodes, or the back electrode is formed of a plurality of segment electrodes. A liquid crystal display element according to a second aspect, which is a plurality of common electrodes arranged corresponding to each segment electrode.

In a fifth aspect, at least a part of the front-side electrode is a striped electrode, and at least a part of the back-side electrode is a stripe-shaped electrode. A liquid crystal display element according to a second aspect, which is arranged so as to intersect in a substrate plane, is provided.

In a sixth aspect, a liquid crystal layer is sandwiched between a front substrate provided with a front electrode and a back substrate provided with a back electrode, and the liquid crystal layer has a plurality of display states. In a liquid crystal display element in which a display state is changed by a voltage applied to at least one of the display states and at least one of the display states is stably maintained, at least a part of the front side electrode and the front side substrate is transparent, and the front side electrode or The back side electrode is divided into a plurality of electrode regions on each substrate surface, an antiferroelectric liquid crystal is used for a liquid crystal layer, a maximum distance a (μm) between adjacent electrode regions, and a thickness d (μm) of the liquid crystal layer. And a maximum voltage V _OP (V) of voltages applied to the front and back electrodes satisfies a relational expression of 1.0 · d ≦ a ≦ d · V _OP / 40. An element is provided.

According to a seventh aspect, there is provided the liquid crystal display device according to the sixth aspect, wherein V _OP is 120 V or less and 0.5 μm ≦ d ≦ 6.0 μm.

According to an eighth aspect, there is provided a liquid crystal display using the liquid crystal display element according to any one of the first to seventh aspects, which is a display of a public display or a vehicle. .

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a uniform alignment state can be obtained in both liquid crystal regions in a pixel portion and a line portion. In particular, in a dot matrix display, a decrease in contrast ratio can be avoided. In the segment display, it is possible to prevent the display from being erroneously recognized due to the reflection state of the edge (between lines) of the pixels.

According to a preferred embodiment of the present invention, CL-L
A cholesteric liquid crystal or a chiral nematic liquid crystal is used for a liquid crystal layer of the CD, and a liquid crystal layer of the AF-LCD includes:
An antiferroelectric liquid crystal is used.

Although the present invention can be applied to non-full dot display such as segment display, it has a larger effect in the case of dot matrix display having a large number of inter-line portions within a certain area. For example, 100x400, 200x600
It is useful for medium to large sizes such as dot size. Alternatively, by forming a thin electrode pattern, L _d ≧
6, when performing high definition display, the visibility of the display can be sufficiently ensured.

Here, an electrode portion (intersection) opposingly disposed between the first substrate and the second substrate is defined as a pixel portion, and a space between electrodes adjacent to each other on the same substrate surface is defined as an interline portion. . In the pixel part, due to the electric field generated by the counter electrode,
The orientation of the liquid crystal is mainly controlled.

On the other hand, since there is no electrode on at least one substrate side between the lines, it is considered that the alignment of the liquid crystal is affected by various factors. For example, the leakage electric field due to the distortion of the equipotential surface at the edge of the electrode,
The alignment state of the liquid crystal in the pixel portion determined by the electric field, the alignment regulating force at the substrate interface, and the like.

Further, when line-sequential driving is performed, a potential difference occurs between adjacent transparent electrodes. The first substrate and the second
Large distortion occurs in the equipotential surface between any four adjacent electrodes of the substrate. This distortion of the equipotential surface also causes a change in the orientation of the liquid crystal in the portion between the lines.

Therefore, in order to control the alignment state of the liquid crystal by the electric field in both the pixel portion and the line portion, the maximum distance a between the adjacent electrode regions on the same substrate surface and the thickness d of the liquid crystal layer (liquid crystal panel (Hereinafter, referred to as a layer thickness d) is 1.0 · d ≦ a ≦ 4.0.
It is necessary to satisfy the relational expression of d.

In the case of a chiral nematic liquid crystal display device, it is necessary to satisfy a relational expression of 1.0 · d ≦ a ≦ d · V _max / 10. In the case of an antiferroelectric liquid crystal display device, it is necessary to satisfy a relational expression of 1.0 · d ≦ a ≦ d · V _OP / 40.

The case where display is performed by driving a chiral nematic liquid crystal will be described below. As the pulse width of the voltage applied to the selected pixel, a voltage that can be supplied by a drive device that can be normally used is assumed. That is, in the case of static driving, a voltage pulse having a pulse width of 1000 ms or less and a maximum effective voltage of 48 V _max or less is applied. When line-sequential driving is performed in dot matrix display, the selection time for one column is 100 ms or less at room temperature.

In this case, when a> _d.Vmax / 10, it is extremely difficult to change the alignment state of the liquid crystal in the interline portion. This is because, under certain driving conditions, when the maximum distance a is relatively large with respect to the layer thickness d, the electric field acting on the liquid crystal in the interline portion becomes weak.

In particular, in the case of performing dot matrix display, the liquid crystal region to which an external force is applied changes to the reflection state (PL state), so that the background luminance when presenting the background color in the FC state increases. For this reason, the contrast ratio of the display decreases. In the case of the segment display, a part that should not be visually recognized is bordered and becomes visible, and the original display itself tends to be difficult to visually recognize.

However, even in the case where the above relational expression is not satisfied, if a high voltage is applied for a long period of time, the alignment state of the liquid crystal between the lines can be restored. For example, even when the layer thickness d is 4 μm and the maximum distance a is 30 μm,
When a voltage of 60 V is applied for 10 seconds, the alignment state of the liquid crystal in the inter-line portion can be restored so as to follow the alignment state (PL state) of the pixel portion.

However, at such a high voltage, the CL-LCD
Is difficult to drive. In addition, the time required to obtain a desired display on the liquid crystal panel surface becomes extremely long, and the basic functions required for the display element cannot be achieved.

On the other hand, when the maximum distance a between adjacent electrode regions is less than 4.0 μm, it becomes difficult to pattern a transparent electrode such as ITO. The probability of causing a short circuit between the electrodes also increases. Alternatively, foreign matter enters between adjacent electrodes, and the probability of occurrence of a short circuit in the display surface increases.

For these reasons, the present invention is configured to satisfy the above relational expression. Further, in consideration of driving by a driving means such as a general-purpose driving IC, CL-L
In the case of a CD, 2.5 μm ≦ d ≦ 6.0 μm, and
It is preferable to satisfy the maximum effective voltage _{V max} ≦ 48V. In the case of an AF-LCD, V _OP is 120
V and 0.5 μm ≦ d ≦ 6.0 μm.

Next, the structure of the liquid crystal display device of the present invention will be described. The liquid crystal display element 1 shown in FIG. 1 includes a first substrate 2 and a second substrate 3. Glass or plastic is used for the substrate, and ITO is used for the electrodes.

Example 1 described below performs full dot matrix display. On the first substrate 2, a plurality of row electrodes 21 having a predetermined interval (interline width) are arranged in parallel in a stripe shape. Also on the second substrate 3, a plurality of column electrodes 31 having a predetermined interval are arranged in parallel in a stripe shape.
The line width between the row electrode 21 and the column electrode 31 was set equal. When the stripe-shaped electrodes are arranged in parallel, the maximum distance a becomes equal to the line width.

In the present invention, the maximum distance a corresponds to an effective length that affects the generation of an electric field in adjacent electrode regions. In the curved part of the electrode, an effective line width may be assumed. Further, when the electrode gap gradually changes, an effective and maximum line distance may be used.

Example 2 performs segment display.
On the first substrate 2, an entire-surface electrode 21 is formed, and on the second substrate 3, an electrode 31 corresponding to a display pixel and an electrode 31 corresponding to a background portion are formed.

On the electrode forming surfaces of the first substrate 2 and the second substrate 3, an electric insulating film and an alignment film are respectively formed (not shown). In addition, a color filter may be provided on the inner surface side of one of the substrates for the purpose of adjusting the visibility. The first substrate 2 and the second substrate 3 are made of a peripheral sealing material 4
And the liquid crystal layer 5 is sealed between the substrates. Then, depending on the positional relationship between the electrodes and the liquid crystal, a line portion A, a line width a, a pixel portion D, a display pixel electrode D1, and a background pixel electrode D2 are provided (see FIGS. 1, 3, and 4).

In Examples 1 and 2, the terminal portion 3a is continuously provided on the second substrate 3, and the lead electrode group 3 is provided on the terminal portion 3a.
2 are formed. Although the column electrodes 31 of the second substrate 3 are directly connected to predetermined electrodes in the extraction electrode group 32,
The row electrodes 21 of the first substrate 2 are electrically connected to predetermined electrodes in the extraction electrode group 32 via transfer materials such as conductive beads included in the peripheral seal material 4. The extraction electrode group is connected to the first substrate and the second electrode without using a transfer material.
May be formed on each of the substrates.

As shown in FIG. 2 and FIG.
The opposing intersection D of the column electrode 31 becomes a pixel. The portion between the lines is the area indicated by the symbol A. Thus, the adjacent row electrode 2
The line portion A is between the lines 1 and 21 and between the adjacent column electrodes 31 and 31.
Becomes

In FIG. 4, D1 is an electrode portion corresponding to a display segment, and D2 is an electrode located in a background portion. Here, the layer thickness d (μm) in the pixel portion is
Attention is paid to the width of the line portion A (line width). That is, assuming that the maximum distance between adjacent row electrodes 21 or adjacent column electrodes 31 is a (μm), in the present invention,
It is configured to satisfy the relational expression of 1.0 · d ≦ a ≦ 4.0 · d.

In the case of a chiral nematic liquid crystal,
It is provided so as to satisfy 0 · d ≦ a ≦ d · V _max / 10. More preferably, 4.0 μm ≦ a and 2.
5 μm ≦ d ≦ 6.0 μm, maximum effective value voltage V _max ≦ 4
The relational expression of 8V is simultaneously satisfied.

With such a configuration, it is possible to apply an electric field intensity from the electrodes located in the pixel portion to the liquid crystal in the interline portion A to change the alignment state. The present invention can be applied not only to a full dot display type liquid crystal display device but also to a liquid crystal display device such as a segment display or a dot character display. Examples 1 to 7 are working examples, and example A is a comparative example.

[0052]

EXAMPLES (Example 1) Two substrates with a transparent conductive film made of ITO were prepared, etched and formed so that the maximum interval a was 10 μm, and 160 stripe electrodes were arranged on each substrate. Then, after forming an electrical insulating layer on the electrode forming surface side of each substrate, a resin solution of polyimide was applied and baked to form an alignment film. Rubbing was not performed on the surface of the alignment film, and the surface was used as it was. The two substrates are arranged so that their stripe electrodes are orthogonal to each other, and a spacer having a diameter of 4 μm is scattered between the opposing surfaces thereof. A peripheral sealing material made of an epoxy resin containing a small amount of glass fiber was applied, and two substrates were bonded to form a cell. Next, a nematic liquid crystal (T _c = 97 ° C., Δn = 0.
242, Δε = 13.8) 66.5 parts, and as a chiral agent, 16.75 parts of an optically active material of the following chemical formula 1 and 16.75 parts of an optically active material of the following chemical formula 2 were mixed to obtain a chiral nematic liquid crystal composition. Prepared. The pitch can be adjusted by the type of the liquid crystal material, the type of the chiral agent, and the mixing ratio of the two. Then, after injecting the chiral nematic liquid crystal composition into the liquid crystal cell using a vacuum injection method, the injection port was sealed with a photocurable resin to form a liquid crystal panel.

Embedded image

Embedded image The substrate surface on the back side of the liquid crystal panel was painted with a matte black paint, and a copper foil tape with a conductive adhesive was stuck to the electrode take-out portion (terminal portion) to short-circuit the stripe electrodes. In the CL-LCD thus formed, P
In the L state, the average direction of the orientation axis (helical axis) of the twisted structure having a constant repetition period (pitch) is substantially perpendicular to the electrode substrate. Selective reflection occurs at a specific wavelength λ determined by the pitch p of the liquid crystal and the average refractive index n _AVG (λ = n _AVG · p). On the other hand, in the FC state, the helical axis points in a direction different from the electrode substrate surface, and part of incident light is scattered but most of light is transmitted. Therefore, the color of the coloring layer provided on the back side is observed from the front side. When a 30 V bipolar rectangular wave pulse having a pulse width of 500 ms and a maximum effective voltage V _max was applied to the electrode extraction portion of the liquid crystal panel, all the pixel portions were in the PL state and reflected green light. Next, 2
A bipolar rectangular wave pulse of 0 V was applied. As a result, weak scattering due to the FC state was exhibited, black as a background color was visually recognized from the front side, and all the pixel portions became black.
The contrast ratio determined by the green overall reflectance in the PL state and the black overall reflectance in the FC state was 10. Next, when the liquid crystal panel was pressed with a finger in a direction perpendicular to the substrate surface, the pressed portion was in a PL state (reflection state) including a portion between lines. Then, when a bipolar rectangular wave pulse having an effective value of 30 V was applied again, both the pixel portion and the interline portion were in a state of total reflection. Further, when a bipolar rectangular wave pulse having an effective value of 20 V was applied, the entire area including the portion between the lines became black. The contrast ratio obtained by dividing the reflectance at the time of reflection by the reflectance of black at this time was 10 and no change was observed, and the display contents changed by the external force could be reproduced without lowering the contrast by rewriting. In this example,
Since the layer thickness d is 4 μm, d · V _max / 10 = 1
2, which satisfies the condition of 10 μm or more in relation to the maximum distance a between the stripe electrodes. In this example, the display state was shifted by applying the voltage pulse only once, so that a long pulse width of about 500 ms was required. When used near room temperature while maintaining a good contrast ratio (≧ 5), 200 ms ≦ T ≦ 600 ms
Can be driven with a pulse width of When driving in a relatively wide temperature range of 0 to 70 ° C. and a small number of application times, a pulse width of 500 ms ≦ T ≦ 1000 ms may be used. When performing multiplex driving,
When the static voltage pulse is applied two or three times, it becomes practically substantially equal, so that the pulse width is
It can be driven in the range of 10 ms ≦ T ≦ 50 ms. Note that since the condition of the contrast ratio required varies depending on the application of the liquid crystal display element, if the condition is relaxed (for example, the contrast ratio ≧ 3), the voltage of the voltage pulse is set to a lower value, or The above pulse width can be set to a shorter value.

(Example 2) Two substrates with a transparent conductive film made of ITO are prepared, and one of the substrates (hereinafter, referred to as an R plate) is used as the entire electrode. The other substrate (hereinafter, F
It is called a board. ) Are provided with seven segment electrodes D1 each of which can display numbers from 0 to 9 by performing on / off operations, and a background electrode D2 corresponding to a background portion (see FIG. 4). The maximum distance a between the segment electrode and the background electrode was 12 μm, and the electrode pattern was formed by etching. Then, after forming an electrical insulating layer on the electrode forming surface side of each substrate, a resin solution of polyimide was applied and baked to form an alignment film. The surface was non-oriented as in Example 1. The two substrates are opposed to each other, and a spacer having a diameter of 4 μm is scattered between the opposing surfaces. Then, except for a portion serving as a liquid crystal injection port, epoxy resin containing a trace amount of glass fibers having a diameter of 4 μm is provided on four sides of the substrate. Apply peripheral sealing material
A liquid crystal cell was fabricated by bonding two substrates. Next, a nematic liquid crystal (Tc = 97 ° C., Δn = 0.242, Δε
= 13.8) 66.5 parts, optical active material 1 of formula 1 above
A chiral nematic liquid crystal composition comprising 6.75 parts and 16.75 parts of the optically active material of the above formula 2 is prepared and injected into a liquid crystal cell by a vacuum injection method, and then the injection port is sealed with a photocurable resin. Then, a liquid crystal panel was formed. One substrate surface of this liquid crystal panel was painted with matte black paint. Then, an electrode extraction portion (terminal portion) corresponding to the background portion is selected from the electrode extraction portions of the F plate, and a bipolar rectangle having a pulse width of 500 ms and an effective value of 20 V is provided between the electrode extraction portion (terminal portion) and the electrode extraction portion of the R plate. A wave pulse was applied. As a result, all the background portions were displayed in black (FC state). Also in this example, driving was performed by applying a single voltage pulse. Next, a copper foil tape with a conductive adhesive is stuck to the five electrode extraction portions (terminal portions) corresponding to the pixels displaying "2" to make a short circuit state, and between this and the electrode extraction portion of the R plate. The pulse width is 500 ms and the effective value is 40
A bipolar bipolar pulse of V was applied. As a result, only the pixel corresponding to the character “2” is in a bright reflection state (PL state) while the above-described black background portion remains as it is,
The letter "2" was correctly displayed. Next, a portion including a pixel portion which is not displayed in the display of "2" was pressed with a finger from a direction perpendicular to the substrate surface. As a result, the pressed portion was in a reflection state including the background portion and the portion between the lines.
Therefore, a bipolar pulse having an effective value of 20 V was again applied to the background electrode, and subsequently a bipolar rectangular wave pulse having an effective value of 40 V was applied to the corresponding pixel electrode. As a result, only the pixel corresponding to the character "2" was in a reflection state on the black background, and the character "2" was correctly displayed. As mentioned above,
The display contents changed by the external force could be restored to the correct display by rewriting. Since the layer thickness d in this example is 4 μm, d · V _max / 10 = 16, which satisfies the condition of 12 μm or more in relation to the maximum distance a. In this example, the entire surface of the common electrode is configured as a solid electrode. However, a plurality of common electrodes may be provided so as to correspond to each digit in units of 7 segments.

(Example A) Except that the maximum distance a was 30 μm on each substrate and 160 stripe electrodes were arranged in parallel.
A liquid crystal cell was produced in the same manner as in Example 1. Layer thickness d is 4μ
m, the maximum distance a between the stripe electrodes is equal to the layer thickness d.
It is 7.5 times. The same chiral nematic liquid crystal composition as in Example 1 was injected into this liquid crystal cell, and the injection port was sealed to form a liquid crystal panel. Also in this liquid crystal panel, a matte black paint was applied to one substrate surface in the same manner as in Example 1. Further, a copper foil tape with a conductive adhesive material was stuck to the electrode take-out portion to short-circuit the stripe electrode. Then, similarly to Example 1, the pulse width is 500 ms and the effective value is 30 V
When the bipolar rectangular pulse was applied, all the pixel portions were in the reflection state (PL state). Next, when a bipolar rectangular wave pulse having an effective value of 20 V was applied in the same manner as in Example 1, all the pixel portions became black (FC state), and the overall reflectance at the time of previous reflection was divided by the overall reflectance of black. The contrast ratio was 9. Next, in the same manner as in Example 1, when the liquid crystal panel was pressed with a finger in a direction perpendicular to the substrate surface, the pressed portion was in a reflection state including the portion between the lines. Then, when a bipolar rectangular wave pulse having an effective value of 30 V was applied again, in this example, the pixel portion was in the state of full-surface reflection, but the portion between the lines did not change, and the entire surface was in the state of reflection. Further, when a bipolar rectangular wave pulse having an effective value of 20 V was applied, the pixel portion turned black, but the portion between the lines remained in a reflection state.
The contrast ratio obtained by dividing the reflectance after application of the V pulse by the reflectance of black at this time was 4, and when the display content changed by the application of the external force was reproduced by rewriting, the contrast ratio was significantly reduced.

(Example 3) An AF-LCD can be formed as follows. An ITO electrode having a parallel pattern with a pitch of 350 μm and a line pitch of 2 μm is formed by etching on a pair of substrates. On the substrate surface, an alignment film for low pretilt is formed by transfer printing so as to have a thickness of about 300 mm, and the alignment films on both substrates are turned in opposite directions using a cotton rubbing cloth (manufactured by Hiroki). Rub. A sealing material is provided around the substrate, cells are formed so that the cell gap of the display unit is about 1.5 μm, and an injection port is provided. Anti-ferroelectric liquid crystal is injected under vacuum heating conditions, and the injection portion is sealed. A polarizing plate is attached to the rear substrate so that the rubbing direction is parallel to the polarization axis, and a polarizing plate is attached to the front substrate so as to be orthogonal to the rear polarization axis. And V
_The energization process is performed by applying a 100 V _PP rectangular wave as an _OP to the liquid crystal cell. The energization process is performed not only on the pixel portion but also on the portion between the lines, so that the orientation of the liquid crystal is aligned. As a result, uniform alignment processing can be achieved on the entire display surface of the liquid crystal display element, and a desired display function can be provided.

(Example 4) A liquid crystal display device for public display can be manufactured using the above liquid crystal display element. It is to display the instrument inside the car. Since high-speed display and a very wide viewing angle are required, it is preferable to use an AF-LCD. Then, it is possible to simultaneously display the traveling speed of the automobile, the accumulated traveling distance, the charge amount of the battery, and the time. FIG. 8 schematically shows an example of the display state. It has a function of restoring a normal display even when the liquid crystal display element is incorporated, or even if the alignment disorder occurs on a part of the liquid crystal display surface due to an external factor.

(Example 5) A guidance display device at an airport or a terminal station can be manufactured using the above-mentioned CL-LCD. The flight number of the plane, the name of the place of departure and arrival, the time, and the name of the advertising company can be displayed simultaneously. Since the display state can be maintained after the power is turned off for a certain period, energy can be saved. When the display information needs to be rewritten, the display can be updated immediately. FIG. 9 schematically shows an example of the display state. Depending on the use environment, an external force may be applied to the display surface, but it has a function of restoring a normal display by rewriting.

(Example 6) A display device for displaying the price of a product can be manufactured using the above-mentioned CL-LCD. Product handling and price can be displayed. Since the display state can be maintained after the power is turned off for a certain period, energy can be saved. If the display information needs to be rewritten,
The display can be updated immediately. FIG. 10 schematically shows an example of the display state. Depending on the use environment, an external force may be applied to the display surface, but it has a function of restoring a normal display by rewriting.

[0059]

As described above, according to the present invention,
In a liquid crystal display element using a liquid crystal layer having memory properties,
The maximum distance a and the layer thickness d between the electrodes adjacent to each other on the same substrate surface are configured to satisfy 1.0 · d ≦ a ≦ 4.0 · d. As a result, not only can basic operations be realized, but also stable operations can be continuously provided under the use environment.

Even if the display changes due to an external factor with respect to the liquid crystal display element, the display contents can be restored without lowering the contrast ratio by performing rewriting. Alternatively, erroneous recognition of the display in the non-display portion can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a chiral nematic liquid crystal display device according to the present invention.

FIG. 2 is a partially enlarged plan view showing an intersection pattern of a row electrode and a column electrode in an embodiment of a chiral nematic liquid crystal display device according to the present invention.

FIG. 3 is a schematic cross-sectional view showing a relationship between respective parts.

FIG. 4 is a plan view showing a pattern of a segment electrode according to a second embodiment.

FIG. 5 is a schematic plan view showing a segment display state in a conventional example.

FIG. 6 is a schematic sectional view of an AF-LCD of the present invention.

FIG. 7 is a graph showing a relationship between an electric field application and transmitted light intensity in an AF-LCD, and a relationship between three layer states.

FIG. 8 is a schematic diagram showing an example in which the liquid crystal display device according to the present invention is used for an indoor display device of an automobile.

FIG. 9 is a schematic diagram showing an example in which the liquid crystal display device according to the present invention is used as a guide display device.

FIG. 10 is a schematic diagram showing an example in which the liquid crystal display device according to the present invention is used for a product price display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display element 2 1st board | substrate 3 2nd board | substrate 4 Peripheral sealing material 5 Liquid crystal layer 21 Row electrode 31 Column electrode 32 Leading electrode group A Line part a Line width D Pixel part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G09F 9/30 330 G09F 9/30 330Z 338 338 342 342Z (72) Inventor Satoshi Niiyama Kanagawa-ku, Yokohama, Kanagawa 1150 Hazawa-machi Asahi Glass Co., Ltd. (72) Inventor Masao Ozeki 1150 Hazawa-machi, Kanagawa-ku, Kanagawa-ku, Kanagawa Prefecture Inside Asahi Glass Co., Ltd. (72) Inventor Kazuhiro Monzen 1-2-1 Kamisakabe, Amagasaki-shi, Hyogo Optrex Amagasaki Factory Co., Ltd.

Claims (8)

[Claims] A liquid crystal layer is sandwiched between a front substrate provided with a front electrode and a back substrate provided with a back electrode, the liquid crystal layer has a plurality of display states, and is controlled by a voltage applied between the electrodes. The display state is transitioned and at least one of the display states is changed.
In the liquid crystal display element in which the state is stably maintained, at least a part of the front side electrode and the front side substrate is transparent, and the front side electrode or the back side electrode is divided into a plurality of electrode regions on each substrate surface, and is adjacent to each other. The maximum distance a (μm) between the electrode regions and the thickness d (μm) of the liquid crystal layer are 1.0 ·
A liquid crystal display device characterized by satisfying a relational expression of d ≦ a ≦ 4.0 · d. 2. A liquid crystal layer is sandwiched between a front substrate provided with a front electrode and a back substrate provided with a back electrode. The liquid crystal layer has a plurality of display states, and is controlled by a voltage applied between the electrodes. The display state is transitioned and at least one of the display states is changed.
In the liquid crystal display element in which the state is stably maintained, at least a part of the front electrode and the front substrate is transparent, and the front electrode or the back electrode is divided into a plurality of electrode regions on each substrate surface, and the liquid crystal layer is formed. Is a chiral nematic liquid crystal, and the maximum distance a (μ
and m), the thickness of the liquid crystal layer d (μm), the maximum effective voltage _{V max} (V) of a voltage applied to the front electrode and the rear electrode is, 1.0 · d ≦ a ≦ d · V m ax / 10. A liquid crystal display element satisfying the following relational expression 10. Wherein V _max is not more than 48V, and,
3. The liquid crystal display device according to claim 2, wherein 2.5 μm ≦ d ≦ 6.0 μm. 4. A common electrode in which at least a part of a front electrode is formed of a plurality of segment electrodes and a back electrode is arranged corresponding to all the segment electrodes, or a back electrode is arranged corresponding to a plurality of segment electrodes. 3. The liquid crystal display device according to claim 2, wherein the plurality of common electrodes are formed. 5. At least a part of the front-side electrode is a stripe electrode, and at least a part of the back-side electrode is a stripe electrode, and each of the front-side electrode and the back-side electrode is crossed in the substrate plane. 3. The liquid crystal display device according to claim 2, wherein the liquid crystal display device is arranged so as to be arranged as follows. 6. A liquid crystal layer is sandwiched between a front substrate provided with a front electrode and a back substrate provided with a back electrode. The liquid crystal layer has a plurality of display states, and is controlled by a voltage applied between the electrodes. The display state is transitioned and at least one of the display states is changed.
In the liquid crystal display element in which the state is stably maintained, at least a part of the front electrode and the front substrate is transparent, and the front electrode or the back electrode is divided into a plurality of electrode regions on each substrate surface, and the liquid crystal layer is formed. An antiferroelectric liquid crystal is used, the maximum distance a (μm) between adjacent electrode regions, the thickness d (μm) of the liquid crystal layer, and the maximum voltage V _OP (V ) And 1.0 · d ≦ a
A liquid crystal display device satisfying a relational expression of ≦ d · V _OP / 40. 7. V _OP is 120 V or less, and
7. The liquid crystal display device according to claim 6, wherein 0.5 μm ≦ d ≦ 6.0 μm. 8. A liquid crystal display device comprising a liquid crystal display device according to claim 1, which is a public display device or a display device of a vehicle.