JP2019012122A - Liquid crystal composition and liquid crystal display element - Google Patents

Abstract

To provide a liquid crystal display element for reducing and suppressing a flicker.SOLUTION: A liquid crystal display element includes: a pair of boards in which a first board and a second board are provided opposingly; a liquid crystal layer clamped by the first board and the second board; a pixel electrode provided in at least one of the first board and the second board; and a common electrode provided in at least one of the first electrode and the second electrode. In the liquid crystal display element, when a first transition current value generated in application of voltage in a homeotropic orientation state is set to I, and a second transition current value is set to I, a liquid crystal layer in which the transition current value Iof the liquid crystal layer is larger than the transition current value Iis used.SELECTED DRAWING: Figure 12

Description

  The present invention relates to a liquid crystal composition and a liquid crystal display element.

  As a display method of a liquid crystal display element used for a clock, a calculator, various measuring instruments, an automobile panel, a printer, a computer, a television, a clock, an advertisement display board, and the like, TN (twisted Nematic) type, STN (super twisted nematic) type, VA (hereinafter also referred to as vertical alignment) type using TFT (thin film transistor), IPS (in-plane switching) type, FFS (fringe field switching) type There are types. Liquid crystal display elements widely used in PC monitors and the like include TN type and STN type, and display methods of liquid crystal display elements widely used in liquid crystal TVs and the like include VA type and IPS type. Examples of a display method of a liquid crystal display element widely used in tablets and tablets include an IPS type and an FFS type. In all these driving methods, there is a demand for liquid crystal display elements that exhibit low-voltage driving, high-speed response, and a wide operating temperature range.

  In particular, as one of the themes of low voltage driving, liquid crystal display elements driven with low power consumption are attracting attention due to the recent social circumstances of energy saving promotion and the spread of smartphones and the like. At present, as means for reducing power consumption, low frequency driving for reducing the driving frequency of the liquid crystal display element from the standard state and intermittent driving for providing a rest period after writing for one frame period are proposed. . However, when the switching from the writing period to the resting period, the voltage changes greatly and the pixel potential fluctuates greatly, resulting in a large difference between the display brightness in the resting period and the display brightness in the writing period of the next frame period. In particular, it has been confirmed that flickering occurs particularly when the frame period is changed, resulting in a problem that display quality is deteriorated.

  In a liquid crystal display element, when a direct current voltage is applied to a liquid crystal layer for a long time, display characteristics change with time due to charge-up, and therefore, frame inversion driving in which positive / negative polarity is inverted every frame is common. Ideally, the alignment state of the liquid crystal molecules is controlled based only on the potential difference between the pixel electrode and the common electrode. However, in reality, the liquid crystal molecules are reversely polarized because a strong electric field acts on the edge of the pixel electrode. However, when the polarity of the electric field is reversed, this polarization reacts instantaneously, and thus flicker occurs due to luminance fluctuations. This reverse polarization is also called flexo polarization. The generation of flicker due to this reverse polarization is a significant technical problem particularly in FFS type liquid crystal display elements.

  Furthermore, human visual perception of flicker depends on the frequency, and it is known that flicker is perceived as the frequency decreases even with luminance fluctuations of the same amplitude, so there is a trade-off between low power consumption driving and flicker reduction. It becomes a relationship.

  As a technique for solving such a problem, there is Patent Document 1. In Patent Document 1, it is disclosed that flicker can be reduced by mixing liquid crystal compounds having different signs in a liquid crystal polar compound used in a liquid crystal display element.

International Publication No. 2015/133194

  In Patent Document 1, the cause of flicker generation is not particularly mentioned, and it can be suppressed by appropriately selecting the components of the liquid crystal composition (paragraph “0041”). In particular, when polar compounds with different signs are mixed and used, a flicker-suppressing effect seems to be recognized. However, by mixing polar compounds with different signs according to any design index, a liquid crystal composition with a high flicker-suppressing effect can be obtained. There is no mention of whether it is possible.

  Accordingly, an aspect of the present invention aims to provide a liquid crystal composition and a liquid crystal display element that can reduce and suppress flicker by paying attention to the relationship between transient current values observed during rotational viscosity measurement of the liquid crystal composition. To do.

  Therefore, the present inventors have intensively studied and solve the above problems by the following means.

(1) In the first aspect of the present invention, a pair of substrates provided with a first substrate and a second substrate facing each other, a liquid crystal layer sandwiched between the first substrate and the second substrate, A liquid crystal display element comprising: a pixel electrode provided on at least one of the first substrate or the second substrate; and a common electrode provided on at least one of the first substrate or the second substrate. ,
In the liquid crystal layer, when a first transient current value generated when a voltage is applied in a homeotropic alignment state is I _p1 and a second transient current value is I _p2 , the transient current value I _{p1 of the} liquid crystal layer Is a liquid crystal display element using a liquid crystal layer larger than the transient current value I _p2 of the liquid crystal.

  (2) The liquid crystal display element according to (1), wherein the pixel electrode and the common electrode are provided on the first substrate.

  (3) The liquid crystal display element according to (1), wherein the pixel electrode and the common electrode are provided on the first substrate, and the pixel electrode is provided closer to the liquid crystal than the common electrode.

  (4) The liquid crystal display element according to (1), wherein the pixel electrode and the common electrode are provided on the first substrate, and the common electrode is provided on a liquid crystal side with respect to the pixel electrode.

(5) A liquid crystal composition contained in a liquid crystal layer filled between electrode substrates, wherein a transient current value I _p1 generated first when a voltage is applied between the electrode substrates is a transient current value generated second time It is a liquid crystal composition having a negative dielectric anisotropy characterized by being larger than _Ip2 .

  (6) The liquid crystal composition contained in the liquid crystal layer includes a liquid crystal compound having a negative dielectric anisotropy and a liquid crystal compound having a positive dielectric anisotropy. It is a negative liquid crystal composition.

  According to the liquid crystal display element using the liquid crystal composition according to the present invention, flicker can be reduced or suppressed.

It is a figure which shows typically an example of a structure of the liquid crystal display element (liquid crystal display part) of this invention. It is the figure which shows typically the structure of the electrode layer 3 of a liquid crystal display part, and is the schematic diagram which showed the pixel part with the equivalent circuit. It is a figure which shows typically the structure of the electrode layer 3 of a liquid crystal display part, and is a schematic diagram which shows an example of the shape of a pixel electrode. It is a figure which shows typically the structure of the electrode layer 3 of a liquid crystal display part, and is a schematic diagram which shows an example of the shape of a pixel electrode. It is a figure which shows typically the structure of the electrode layer 3 of a liquid crystal display part, and is a schematic diagram which shows an example of the shape of a pixel electrode. FIG. 5 is another example of a cross-sectional view of the liquid crystal display element shown in FIG. 1 taken along the line III-III in FIG. It is sectional drawing which cut | disconnected the IPS type | mold liquid crystal display part shown in FIG. 1 in the III-III line direction in FIG. It is a figure which shows typically the structure of the liquid crystal display part of a vertical alignment type liquid crystal display element. It is the top view to which the area | region enclosed by the II line | wire of the electrode layer 3 (or also called thin-film transistor layer 3) containing the thin-film transistor formed on the board | substrate in FIG. 10 is a cross-sectional view of the liquid crystal display element shown in FIG. 8 taken along the line III-III in FIG. It is a figure which shows the experiment example and comparative example of this invention. It is a figure which shows the experiment example and comparative example of this invention. It is a figure which shows the experiment example and comparative example of this invention.

According to a first aspect of the present invention, a pair of substrates provided so that the first substrate and the second substrate are opposed to each other, a liquid crystal layer sandwiched between the first substrate and the second substrate, and the first substrate A liquid crystal display element having a pixel electrode provided on at least one of the first substrate and the second substrate, and a common electrode provided on at least one of the first substrate and the second substrate, In the layer, when the first transient current value generated when a voltage is applied in the homeotropic alignment state is I _p1 and the second transient current value is I _p2 , the transient current value I _{p1 of the} liquid crystal layer is A liquid crystal display element using a liquid crystal layer larger than the transient current value I _{p2 of} the liquid crystal.

When the first transient current value I _p1 generated when a voltage is applied in a homeotropic alignment state of the liquid crystal molecules and the second transient current value I _p2 are measured, the liquid crystal provided in the actual liquid crystal display element Regardless of the orientation state of the layer (homeotropic orientation or homogeneous orientation), the transient current value I _p1 measured with the liquid crystal in the homeotropic orientation state is the transient current value I measured with the liquid crystal composition in the homeotropic orientation state. It was confirmed that flicker can be reduced and suppressed by using a liquid crystal layer larger than _p2 .

The liquid crystal layer of the present invention preferably exhibits negative dielectric anisotropy. In the present invention, the first transient current value I _p1 generated when a voltage is applied to the liquid crystal composition used in the liquid crystal layer in the homeotropic alignment state and the second transient current value I _p2 are measured. As means for expressing the two transient current values in this way, a liquid crystal composition having a negative dielectric anisotropy and a liquid crystal composition having a negative dielectric anisotropy and a liquid crystal compound having a negative dielectric anisotropy are included. It is preferable to use it for a liquid crystal layer. Although the entire liquid crystal layer exhibits negative dielectric anisotropy, it was confirmed that two transient current values were exhibited by including a liquid crystal compound having a positive dielectric anisotropy in the liquid crystal layer. Here, “the first transient current value generated when a voltage is applied in a liquid crystal composition in a homeotropic alignment state is defined as I _p1 ” means that a voltage is applied to liquid crystal molecules that are homeotropically aligned when no voltage is applied. The first transient current value generated at the time is referred to as “the second transient current value is defined as I _p2 ” refers to the transient current value generated after the first transient current value. In the present specification, the “first transient current value I _p1 ” refers to the first transient current as I _p1, and the “second transient current value” refers to the second transient current as I _p2. .

In the conventional liquid crystal composition, the first transient current _Ip1 cannot be observed. The first transient current I _p1 is considered to be due to the action of the added liquid crystal compound having a positive dielectric anisotropy. Specifically, it is considered that this occurs when the liquid crystal molecules in the interior are polarized so as to cancel the charge once charged in the liquid crystal cell. In other words, it is thought that this is due to the dielectric polarization of the liquid crystal molecules. In this case, the liquid crystal composition having a negative dielectric anisotropy as a main component has a positive dielectric anisotropy. It is vertically aligned so that the compound is along. (Additional description of the direction of the electric field) Here, in order to measure the transient current of the liquid crystal composition having a negative dielectric anisotropy, the liquid crystal cell having a pair of counter electrodes is homeotropically aligned. A liquid crystal cell is used. That is, the direction of the electric field applied to the liquid crystal cell and the polarization direction of the liquid crystal compound having a positive dielectric anisotropy coincide with each other. In this state, the polarization of the liquid crystal compound having a positive dielectric anisotropy is considered to work in a direction to cancel the charge once charged in the liquid crystal cell. The process of dielectric polarization of the liquid crystal compound having a positive dielectric anisotropy appears in the relaxation process of the first transient current _Ip1 , and the speed of the dielectric polarization coincides with the relaxation time of the first transient current. .

  In other words, as one of the causes of flickering, the liquid crystal molecules reversely polarize because a strong electric field acts on the edge of the pixel electrode, and this polarization reacts instantaneously when a voltage is applied or the polarity of the electric field is reversed. Therefore, it is considered that the luminance fluctuation occurs. Add a small amount of a positive liquid crystal compound whose dielectric anisotropy is exactly opposite to the liquid crystal composition having a negative dielectric anisotropy, which is the main component, and whose director and polarization directions match. Thus, it is considered that the flicker is suppressed by relaxing or reducing the reverse polarization of the liquid crystal compound exhibiting negative dielectric anisotropy by the liquid crystal compound exhibiting positive dielectric anisotropy. Therefore, the liquid crystal composition having a negative dielectric anisotropy, which is the main component, regardless of whether the direction of the electric field when applying a voltage is horizontal to the substrate or the direction of the electric field when applying voltage is perpendicular to the substrate The dielectric anisotropy with the liquid crystal compound exhibiting positive dielectric anisotropy and the directional relationship of the director remain unchanged. In addition, the liquid crystal composition has a negative dielectric anisotropy and a positive dielectric anisotropy regardless of whether the alignment direction of liquid crystal molecules when no voltage is applied is homeotropic or homeotropic. The dielectric anisotropy with the liquid crystal compound and the directional relationship of the director remain unchanged.

  Therefore, in a liquid crystal composition having a negative dielectric anisotropy including a liquid crystal compound exhibiting a positive dielectric anisotropy and a liquid crystal compound exhibiting a negative dielectric anisotropy, the negative dielectric anisotropy is reduced. It is considered that the liquid crystal compound exhibiting positive dielectric anisotropy has an effect of relaxing or reducing the reverse polarization of the liquid crystal compound.

Furthermore, as described above, the first (first) transient current I _p1 is caused by a liquid crystal compound having a positive dielectric anisotropy, and the second (second) transient current I _p1 is a dielectric anisotropy. This is considered to be due to the negative liquid crystal compound. Therefore, a transient current generated by applying a voltage to liquid crystal in a homeotropic alignment state (a liquid crystal composition exhibiting negative dielectric anisotropy and including a liquid crystal compound having a positive dielectric anisotropy) The FFS type in which a voltage is applied to homogeneously oriented liquid crystal (a liquid crystal composition having a negative dielectric anisotropy and including a liquid crystal compound having a positive dielectric anisotropy) It is considered that the present invention can be applied to an IPS type liquid crystal display element, and such an experimental result (described later) is actually obtained.

  In general, a method of measuring a transient current value by using the transient current value in order to calculate the rotational viscosity γ1 of the liquid crystal composition is known. The details of the relationship between the rotational viscosity γ1 and the transient current will be described in the explanation of the experimental results to be described later, but the electric capacity changes due to the change in the director (major axis direction) of the liquid crystal molecules when a voltage is applied. Then, by measuring the transient current value corresponding to the changed electric capacity, the rotational viscosity γ1 (also referred to as rotational viscosity) is calculated from the relational expression between the change rate of the electric capacity (transient current value) and the director rotation. Yes.

  For example, when the liquid crystal layer uses a liquid crystal composition exhibiting positive dielectric anisotropy, the rotational viscosity γ1 is measured by a pair of alignment films that have anti-parallel horizontal alignment (homogeneous alignment) on the surface. A liquid crystal layer is filled between the opposite electrodes of the substrate, and a voltage is applied to the opposite electrode, whereby the liquid crystal molecules are tilted from the horizontal alignment (homogeneous alignment) to the vertical alignment (homeotropic alignment) with respect to the substrate. Measuring the change of the rect. On the other hand, when the liquid crystal layer uses a liquid crystal composition exhibiting a negative dielectric anisotropy, the rotational viscosity γ1 is measured by measuring a pair of opposing layers each having an alignment film for vertical alignment (homeotropic alignment). Measuring the change in director caused by tilting liquid crystal molecules from vertical alignment (homeotropic alignment) to horizontal alignment (homogeneous alignment) by filling the liquid crystal layer between the electrodes and applying a voltage to the counter electrode doing. For this reason, the liquid crystal in a homeotropic alignment state (a liquid crystal composition exhibiting negative dielectric anisotropy and including a liquid crystal compound having a positive dielectric anisotropy) is also used for reasons related to the measurement principle and measurement apparatus. The relationship between the magnitudes of transient current values generated by applying a voltage to a homogeneous liquid crystal (a liquid crystal composition exhibiting negative dielectric anisotropy and a liquid crystal compound having a positive dielectric anisotropy) In other words, the liquid crystal display element is applied to an FFS type or IPS type liquid crystal display element.

  Since the electric capacity depends on the ratio of the dielectric constant in the major axis direction to the minor axis direction of the liquid crystal molecules, the electric capacity does not change in an in-plane (in-plane change) in which the direction of the director does not change.

  Hereinafter, preferred embodiments of a liquid crystal display device according to the present invention will be described with reference to the drawings.

  The liquid crystal display element according to the present invention preferably includes a liquid crystal display unit (so-called liquid crystal panel) and a display processing unit. The liquid crystal display unit seals a liquid crystal layer between a driving substrate in which a driving circuit including a pixel electrode and a thin film transistor is provided for each pixel and a counter substrate, as will be described with reference to FIGS. It is a thing.

  The display processing unit performs processing such as frame rate conversion on the video signal, and controls the backlight and the liquid crystal display unit according to the processing result.

  Hereinafter, after explaining the liquid crystal display part of the liquid crystal display element according to the present invention, the operation and action of the display processing part will be explained based on the drawings.

  An embodiment of a liquid crystal display unit of a liquid crystal display element according to the present invention will be described. FIG. 1 is a diagram schematically illustrating a configuration of a liquid crystal display unit of a liquid crystal display element. In FIG. 1, for convenience of explanation, each component is illustrated separately. As shown in FIG. 1, the liquid crystal display element 10 according to the present invention includes a first (transparent insulating) substrate (also referred to as a transparent substrate) 2 and a second (transparent insulating) substrate 7 which are disposed to face each other. It is a liquid crystal display element which has a liquid-crystal composition (or liquid-crystal layer 5) pinched | interposed between. The first (transparent insulating) substrate 2 has an electrode layer 3 formed on the surface on the liquid crystal layer 5 side. In addition, an alignment film 4 is provided between the liquid crystal layer 5 and each of the first (transparent insulating) substrate 2 and the second (transparent insulating) substrate 7, and when the voltage is not applied by the alignment film 4. Liquid crystal molecules in the liquid crystal composition can be aligned in a predetermined direction with respect to the recording substrates 2 and 7. Further, in FIG. 1, the pixel electrode and the common electrode are provided on the first substrate 2 side as the electrode layer 3, but the pixel electrode is provided on the first substrate 2 and the common electrode is provided on the second substrate 7. May be.

  FIG. 1 shows a mode in which the second substrate 7 and the first substrate 2 are sandwiched between a pair of polarizing plates 1 and 8, but the position where the polarizing plates 1 and 8 are provided is limited to this figure. It doesn't mean. Further, in FIG. 1, a color filter 6 is provided between the second substrate 7 and the alignment film 4. The liquid crystal display element according to the present invention may be a so-called color filter on array (COA), or a color filter 6 may be provided between the electrode layer 3 and the liquid crystal phase 5, or the electrode layer. A color filter may be provided between 3 and the first substrate 2. In addition, if necessary, an overcoat layer (not shown) may be provided so as to cover the color filter layer 6 to prevent a substance contained in the color filter layer from flowing out to the liquid crystal layer.

  1 to 10, as a preferred embodiment of the liquid crystal display element of the present invention, the liquid crystal layer 5 and the first substrate 2 and the liquid crystal layer 5 and the second substrate 7 are respectively described as preferred embodiments. Although the example in which the alignment film 4 is formed on the first substrate and the second substrate is described, the liquid crystal display element of the present invention is formed on at least one of the first substrate 2 and the second substrate 7. The alignment film 4 should just be formed. For example, when the alignment film 4 is formed between the liquid crystal layer 5 and the first substrate 2 so as to contact the liquid crystal layer 5 on the first substrate 2, the other liquid crystal layer 5 and the second substrate 2 An alignment film may not be provided between the substrate 7 and the substrate 7.

  That is, the liquid crystal display element 10 according to the present invention includes a first substrate 2, an electrode layer 3, an alignment film 4, a liquid crystal layer 5 containing a liquid crystal composition, an alignment film 4, a color filter 6, It is preferable to include a configuration in which two substrates 7 are sequentially stacked.

  The first substrate 2 and the second substrate 7 can be made of a flexible material such as glass or plastic, at least one of which is a transparent material and the other is a transparent material. An opaque material such as The two substrates are bonded together by a sealing material and a sealing material such as an epoxy thermosetting composition disposed in the peripheral region, and in order to maintain the distance between the substrates, for example, glass particles, Spacer columns made of granular spacers such as plastic particles and alumina particles or a resin formed by photolithography may be arranged.

  2 to 5 are schematic views of the structure diagram of the electrode layer 3 of the liquid crystal display unit. More specifically, FIG. 2 is a schematic view showing the pixel portion in an equivalent circuit, and FIG. 3 and FIG. It is a schematic diagram which shows an example of the shape of a pixel electrode. 3 to 4, as an example of the present embodiment, an FFS type liquid crystal display element including a liquid crystal display unit including pixels arranged in a mesh pattern. A liquid crystal display device is driven by providing a backlight as illumination means for illuminating the liquid crystal display unit from the back side. Examples of the light source of the backlight include those using a light emitting diode or a cold cathode tube.

  In FIG. 2, the electrode layer 3 according to the present invention includes a common electrode and a plurality of pixel electrodes. The pixel electrode is disposed on the common electrode via an insulating layer (for example, silicon nitride (SiN)). The pixel electrode is disposed for each display pixel, and a slit-shaped opening is formed. The common electrode and the pixel electrode are transparent electrodes formed of, for example, ITO (Indium Tin Oxide), and the electrode layer 3 has a gate bus line GBL (extending along a row in which a plurality of display pixels are arranged in the display portion. GBL1, GBL2,... GBLm), a source bus line SBL (SBL1, SBL2,... SBLm) extending along a column in which a plurality of display pixels are arranged, and a vicinity of a position where the gate bus line and the source bus line intersect. In addition, a thin film transistor is provided as a pixel switch. The gate electrode of the thin film transistor is electrically connected to the corresponding gate bus line GBL, and the source electrode of the thin film transistor is electrically connected to the corresponding signal line SBL. Further, the drain electrode of the thin film transistor is electrically connected to the corresponding pixel electrode.

  The electrode layer 3 includes a gate driver and a source driver as driving means for driving a plurality of display pixels, and the gate driver and the source driver are arranged around the liquid crystal display unit. The plurality of gate bus lines are electrically connected to the output terminal of the gate driver, and the plurality of source bus lines are electrically connected to the output terminal of the source driver.

  The gate driver sequentially applies an ON voltage to the plurality of gate bus lines, and supplies the ON voltage to the gate electrode of the thin film transistor electrically connected to the selected gate bus line. Conduction is established between the source and drain electrodes of the thin film transistor in which the ON voltage is supplied to the gate electrode. The source driver supplies an output signal corresponding to each of the plurality of source bus lines. The signal supplied to the source bus line is applied to the corresponding pixel electrode through a thin film transistor in which the source and drain electrodes are electrically connected. The operations of the gate driver and the source driver are controlled by a display processing unit (also referred to as a control circuit) arranged outside the liquid crystal display element.

The display processing unit according to the present invention preferably has a low frequency driving function or an intermittent driving function for reducing driving power in addition to normal driving, and is used for driving the gate bus line of the TFT liquid crystal panel. It controls the operation of the gate driver which is an LSI and the operation of the source driver which is an LSI for driving the source bus line of the TFT liquid crystal panel. In addition, the common voltage V _COM is supplied to the common electrode to control the operation of the backlight.

  In the low-frequency driving in which the driving frequency of the liquid crystal display element is reduced from the standard state and the intermittent driving in which the rest period is provided after writing for one frame period, the voltage changes greatly when switching from the writing period to the rest period. Since the potential fluctuates greatly, the difference between the display brightness in the pause period and the display brightness in the writing period of the next frame period increases, and flicker occurs particularly when the frame period is switched, resulting in a deterioration in display quality. Has been confirmed to occur. Human flicker visual perception depends on the frequency, and it is known that flicker is more visible as the frequency decreases even with luminance fluctuations of the same amplitude, so there is a trade-off between low power consumption driving and flicker reduction. Become. Therefore, when the liquid crystal display element according to the present invention is provided with low frequency driving or intermittent driving, it is preferable because the flicker reducing effect is exhibited.

  FIG. 3 is a diagram showing a comb-shaped pixel electrode as an example of the shape of the pixel electrode, and is an enlarged plan view of a region surrounded by the II line of the electrode layer 3 formed on the substrate 2 in FIG. . As shown in FIG. 3, the electrode layer 3 including a thin film transistor formed on the surface of the first substrate 2 includes a plurality of gate bus lines 26 for supplying scanning signals and a plurality of gate bus lines 26 for supplying display signals. The source bus lines 25 are arranged in a matrix so as to cross each other. A unit pixel of the liquid crystal display device is formed by a region surrounded by the plurality of gate bus lines 26 and the plurality of source bus lines 25, and a pixel electrode 21 and a common electrode 22 are formed in the unit pixel. ing. A thin film transistor including a source electrode 27, a drain electrode 24, and a gate electrode 28 is provided in the vicinity of the intersection where the gate bus line 26 and the source bus line 25 intersect each other. The thin film transistor is connected to the pixel electrode 21 as a switch element that supplies a display signal to the pixel electrode 21. A common line 29 is provided in parallel with the gate bus line 26. The common line 29 is connected to the common electrode 22 in order to supply a common signal to the common electrode 22.

  A common electrode 22 is formed on the back surface of the pixel electrode 21 with an insulating layer 18 (not shown) interposed therebetween. The shortest separation distance between the adjacent common electrode and the pixel electrode is shorter than the shortest separation distance between the alignment layers. The surface of the pixel electrode is preferably covered with a protective insulating film and an alignment film layer. Note that a storage capacitor 23 for storing a display signal supplied through the source bus line 25 may be provided in a region surrounded by the plurality of gate bus lines 26 and the plurality of source bus lines 25.

  FIG. 4 is a modification of FIG. 3 and shows a slit-shaped pixel electrode as an example of the shape of the pixel electrode. The pixel electrode 21 shown in FIG. 4 has a substantially rectangular flat plate electrode cut out at the center and both ends of the flat plate with a triangular cutout, and the other portions are cut out in a substantially rectangular frame shape. The shape is hollowed out at the part. The shape of the notch is not particularly limited, and a notch having a known shape such as an ellipse, a circle, a rectangle, a rhombus, a triangle, or a parallelogram can be used.

  3 and 4 show only a pair of gate bus lines 26 and a pair of source bus lines 25 in one pixel.

  FIG. 6 is another example of a cross-sectional view of the liquid crystal display element shown in FIG. 1 cut along the line III-III in FIG. 3 or FIG. The first substrate 2 on which the alignment layer 4 and the electrode layer 3 including the thin film transistor are formed on the surface and the second substrate 8 on which the alignment layer 4 is formed on the surface are spaced apart from each other with a predetermined gap G. This space is filled with a liquid crystal layer 5 containing a liquid crystal composition. A gate insulating film 12, a common electrode 22, an insulating film 18, a pixel electrode 21, and an alignment layer 4 are sequentially stacked on a part of the surface of the first substrate 2.

  A preferred embodiment of the structure of the thin film transistor is, for example, as shown in FIG. 6, provided to cover the gate electrode 11 formed on the surface of the substrate 2 and the gate electrode 11 and cover the substantially entire surface of the substrate 2. A gate insulating layer 12, a semiconductor layer 13 formed on the surface of the gate insulating layer 12 so as to face the gate electrode 11, and a protective film provided so as to cover a part of the surface of the semiconductor layer 13 14, a drain electrode 16 provided so as to cover one side end of the protective layer 14 and the semiconductor layer 13 and to be in contact with the gate insulating layer 12 formed on the surface of the substrate 2, and the protection A source electrode 17 which covers the film 14 and the other side edge of the semiconductor layer 13 and is in contact with the gate insulating layer 12 formed on the surface of the substrate 2; And 16 and the source electrode 17 insulating protective layer 18 provided to cover the, the it has. An anodic oxide film (not shown) may be formed on the surface of the gate electrode 11 for reasons such as eliminating a step with the gate electrode.

  In the embodiment shown in FIGS. 3 and 4, the common electrode 22 is a flat electrode formed on almost the entire surface of the gate insulating layer 12, while the pixel electrode 21 is an insulating protective layer 18 covering the common electrode 22. It is a comb-shaped electrode formed on the top. That is, the common electrode 22 is disposed at a position closer to the first substrate 2 than the pixel electrode 21, and these electrodes are disposed so as to overlap each other via the insulating protective layer 18. The pixel electrode 21 and the common electrode 22 are formed of a transparent conductive material such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), or IZTO (Indium Zinc Tin Oxide). Since the pixel electrode 21 and the common electrode 22 are formed of a transparent conductive material, the area opened by the unit pixel area increases, and the aperture ratio and transmittance increase.

  Further, the pixel electrode 21 and the common electrode 22 have an interelectrode distance (also referred to as a minimum separation distance) R between the pixel electrode 21 and the common electrode 22 in order to form a fringe electric field between these electrodes. It is formed to be smaller than the thickness G of the liquid crystal layer 5 between the first substrate 2 and the second substrate 7. Here, the inter-electrode distance R represents the distance in the horizontal direction on the substrate between the electrodes. In FIG. 3, since the flat common electrode 22 and the comb-shaped pixel electrode 21 overlap each other, an example in which the minimum separation distance (or interelectrode distance): R = 0 is shown, and the minimum separation distance R is The thickness of the liquid crystal layer between the first substrate 2 and the second substrate 7 (also referred to as a cell gap): smaller than G, and thus a fringe electric field E is formed. Therefore, the FFS type liquid crystal display element can use a horizontal electric field formed in a direction perpendicular to a line forming the comb shape of the pixel electrode 21 and a parabolic electric field. The electrode width of the comb-shaped portion of the pixel electrode 21: l and the width of the gap of the comb-shaped portion of the pixel electrode 21: m are such that all the liquid crystal molecules in the liquid crystal layer 5 can be driven by the generated electric field. It is preferable to form. The minimum separation distance R between the pixel electrode and the common electrode can be adjusted as the (average) film thickness of the gate insulating film 12.

  An example of an IPS type liquid crystal display element, which is an FFS type modification of the liquid crystal display portion of the liquid crystal display element according to the present invention, will be described with reference to FIGS. The configuration of the IPS liquid crystal display element is a structure in which an electrode layer 3 (including a common electrode, a pixel electrode, and a TFT) is provided on one substrate as in the FFS type of FIG. Plate 1, first substrate 2, electrode layer 3, alignment film 4, liquid crystal layer 5 containing a liquid crystal composition, alignment film 4, color filter 6, second substrate 7, and second The polarizing plates 8 are sequentially laminated.

FIG. 5 is an enlarged plan view of a part of the region surrounded by the II line of the electrode layer 3 formed on the first substrate 2 of FIG. 1 in the IPS type liquid crystal display unit. As shown in FIG. 5, in a region surrounded by a plurality of gate bus lines 26 for supplying scanning signals and a plurality of data bus lines 25 for supplying display signals (in a unit pixel), a comb-teeth shape is formed. The first electrode (for example, pixel electrode) 21 and the comb-shaped second electrode (for example, common electrode) 22 are loosely engaged with each other (the two electrodes are spaced apart and meshed with each other while maintaining a certain distance). Is provided). In the unit pixel, a thin film transistor including a source electrode 27, a drain electrode 24, and a gate electrode 28 is provided in the vicinity of an intersection where the gate bus line 26 and the source bus line 25 intersect each other. The thin film transistor is connected to the first electrode 21 as a switch element that supplies a display signal to the first electrode 21. Further, a common line (V _com ) 29 is provided in parallel with the gate bus line 26. The common line 29 is connected to the second electrode 22 in order to supply a common signal to the second electrode 22.

  7 is a cross-sectional view of the IPS liquid crystal display unit shown in FIG. 1 cut along the line III-III in FIG. On the first substrate 2, a gate insulating layer 32 is provided so as to cover the gate bus line 26 (not shown) and to cover substantially the entire surface of the first substrate 2, and on the surface of the gate insulating layer 32. The formed insulating protective layer 31 is provided, and on the insulating protective film 31, a first electrode (pixel electrode) 21 and a second electrode (common electrode) 22 are provided separately. The insulating protective layer 31 is a layer having an insulating function, and is formed of silicon nitride, silicon dioxide, silicon oxynitride film, or the like.

  In the embodiment shown in FIGS. 5 and 7, the first electrode 21 and the second electrode 22 are comb-shaped electrodes formed on the insulating protective layer 31, that is, on the same layer, and are separated from each other. And are engaged with each other. In the IPS liquid crystal display unit, the interelectrode distance G between the first electrode 21 and the second electrode 22 and the thickness of the liquid crystal layer between the first substrate 2 and the second substrate 7 ( Cell gap): H satisfies the relationship G ≧ H. The distance between electrodes: G represents the shortest distance in the horizontal direction with respect to the substrate between the first electrode 21 and the second electrode 22. In the example shown in FIGS. 5 and 7, the first electrode 21 is used. And a distance in the vertical direction with respect to a line alternately formed by loosely fitting the second electrode 22. The distance H between the first substrate 2 and the second substrate 7 represents the thickness of the liquid crystal layer between the first substrate 2 and the second substrate 7, specifically, the first The distance (namely, cell gap) between the alignment films 4 (outermost surfaces) provided on each of the substrate 2 and the second substrate 7 and the thickness of the liquid crystal layer are represented.

  On the other hand, in the above-described FFS type liquid crystal display unit, the thickness of the liquid crystal layer between the first substrate 2 and the second substrate 7 is between the first electrode 21 and the second electrode 22. The IPS liquid crystal display unit is less than the shortest distance in the horizontal direction with respect to the substrate, and the thickness of the liquid crystal layer between the first substrate 2 and the second substrate 7 is the same as that of the first electrode 21 and the second electrode. More than the shortest distance in the horizontal direction with respect to the substrate between the electrodes 22. Therefore, the difference between IPS and FFS does not depend on the positional relationship between the first electrode 21 and the second electrode 22 in the thickness direction.

  The IPS liquid crystal display element drives liquid crystal molecules using an electric field in a horizontal direction with respect to a substrate surface formed between the first electrode 21 and the second electrode 22. The electrode width Q of the first electrode 21 and the electrode width R of the second electrode 22 are preferably formed such that all the liquid crystal molecules in the liquid crystal layer 5 can be driven by the generated electric field.

  The liquid crystal display element according to the present invention is preferably an FFS type or IPS type liquid crystal display element, and the pixel electrode and the common electrode are preferably provided on the first substrate.

  The liquid crystal display element according to the present invention is more preferably an FFS type liquid crystal display element, wherein the pixel electrode and the common electrode are provided on the first substrate, and the pixel electrode is provided on the liquid crystal side from the common electrode. preferable.

  The liquid crystal display element according to the present invention is more preferably an FFS type liquid crystal display element. The pixel electrode and the common electrode are preferably provided on the first substrate, and the common electrode is preferably provided on the liquid crystal side from the pixel electrode. . In this embodiment, the positional relationship between the pixel electrode and the common electrode in the thickness direction is reversed.

  Another preferred embodiment of the present invention is a vertical alignment type liquid crystal display element. FIG. 8 is a diagram schematically illustrating a configuration of a liquid crystal display unit of a vertical alignment type liquid crystal display element. Further, in FIG. 8, for convenience of explanation, each component is illustrated separately. FIG. 9 is an enlarged plan view of a region surrounded by the II line of the electrode layer 3 (or also referred to as the thin film transistor layer 3) including the thin film transistor formed on the substrate in FIG. 10 is a cross-sectional view of the liquid crystal display element shown in FIG. 1 taken along the line III-III in FIG. Hereinafter, a vertical alignment type liquid crystal display unit according to the present invention will be described with reference to FIGS.

  The configuration of the liquid crystal display element 10 according to the present invention includes a second substrate 7 provided with a transparent electrode (layer) 3 ′ (also referred to as a common electrode 3 ′) made of a transparent conductive material as shown in FIG. And a first substrate 2 including an electrode layer 3 on which a pixel electrode and a thin film transistor for controlling the pixel electrode included in each pixel are formed, and the first substrate 2 and the second substrate 7. A liquid crystal display element having a liquid crystal composition (or liquid crystal layer 5), wherein the alignment of liquid crystal molecules in the liquid crystal composition when no voltage is applied is substantially perpendicular to the substrates 2 and 7, The liquid crystal composition is characterized in that the liquid crystal composition of the present invention is used. As shown in FIGS. 8 and 10, the first substrate 2 and the second substrate 7 may be sandwiched between a pair of polarizing plates 1 and 8. Further, in FIG. 8, a color filter 6 is provided between the second substrate 7 and the common electrode 3 '. Further, a pair of alignment films 4 are formed on the surfaces of the transparent electrodes (layers) 3 and 3 ′ so as to be in direct contact with the liquid crystal composition constituting the liquid crystal layer 5 adjacent to the liquid crystal layer 5 according to the present invention. Also good.

  FIG. 9 is a diagram showing an inverted L-shaped pixel electrode as an example of the shape of the pixel electrode 21, and an area surrounded by the II line of the electrode layer 3 formed on the substrate 2 in FIG. 8 is enlarged. It is a top view. 3 and 4, the pixel electrode 21 is formed in an inverted L shape on substantially the entire surface surrounded by the gate bus line 26 and the source bus line 25. The shape of the pixel electrode is as follows. It is not limited.

  Unlike the IPS type and FFS type, the liquid crystal display portion of the vertical alignment type liquid crystal display element is formed with a common electrode 22 (not shown) facing and separating from the pixel electrode 21. In other words, the pixel electrode 21 and the common electrode 22 are formed on different substrates. On the other hand, in the aforementioned FFS or IPS type liquid crystal display element, the pixel electrode 21 and the common electrode 22 are formed on the same substrate.

  Further, the color filter 6 preferably forms a black matrix (not shown) in a portion corresponding to the thin film transistor and the storage capacitor 23 from the viewpoint of preventing light leakage.

  10 is a cross-sectional view of the liquid crystal display element shown in FIG. 8 taken along the line III-III in FIG. That is, the liquid crystal display element 10 according to the present invention includes a first polarizing plate 1, a first substrate 2, an electrode layer (or also referred to as a thin film transistor layer) 3 including a thin film transistor, an alignment film 4, and a liquid crystal composition. The layer 5 including the alignment layer 4, the common electrode 3 ′, the color filter 6, the second substrate 7, and the first polarizing plate 8 are sequentially stacked. A preferred embodiment of the structure of the thin film transistor (region IV in FIG. 10) of the liquid crystal display element according to the present invention is as described above, and is omitted here.

  Next, the operation and action of the display processing unit of the preferred liquid crystal display element of the present invention will be described below.

The display processing unit according to the present invention preferably has a low frequency driving function or an intermittent driving function for reducing driving power in addition to normal driving, and is used for driving the gate bus line of the TFT liquid crystal panel. It has a function of controlling a gate driver that is an LSI and a source driver that is an LSI for driving a source bus line of a TFT liquid crystal panel. Further, a function of supplying the common voltage V _COM to the common electrode and controlling the operation of the backlight may be provided.

  In the display processing unit, the liquid crystal display unit is driven, the frame frequency of the image signal to the pixel electrode is controlled to be in a range of 60 Hz or less and 0.1 Hz or more, and the cycle of rewriting the image signal to the pixel electrode ( = Rewriting cycle) is preferably freely adjustable. In other words, after the image signal (voltage) is applied to the pixel electrode, the time from when the image signal (voltage) is next applied to the pixel electrode is controlled by the display processing unit so as to be freely adjustable. For this reason, the frame frequency, which is the number of times one screen is scanned (rewritten) per unit second, is controlled by the display processing unit so as to be freely contractible.

  In other words, it is preferable that the display processing unit controls the frame frequency of the image signal to the pixel electrode in a range of 60 Hz or less and 0.1 Hz or more so that the frame frequency of the image signal can be expanded or contracted.

  As a mode in which the cycle of rewriting the image signal to the pixel electrode is lengthened (= the frame frequency of the image signal is lengthened), the first frame frequency is changed from the first drive mode that is driven at the first frame frequency. A second driving mode in which driving is performed at a lower second frame frequency can be given. For example, an example of switching from normal driving (first driving mode) with a frame frequency of 30 to 60 Hz to low frequency driving (third driving mode) with a frame frequency of 0.1 to 15 Hz can be given. Other examples include switching from normal driving (first driving mode) in a frame frequency range of 30 to 60 Hz to intermittent driving (second driving mode) in which a pause period corresponding to more than one frame is provided. It is done.

  The liquid crystal composition constituting the liquid crystal layer according to the present invention includes a polar compound having an absolute value of dielectric anisotropy (Δε) of more than 2, and an absolute value of dielectric anisotropy (Δε) of 0 or more and 2 or less. It preferably contains a nonpolar compound. The liquid crystal composition according to the present invention preferably exhibits a negative dielectric anisotropy and is preferably a nematic liquid crystal composition. Therefore, the liquid crystal composition constituting the liquid crystal layer according to the present invention includes a liquid crystal component including a liquid crystal compound exhibiting a negative dielectric anisotropy having a dielectric anisotropy (Δ∈ is less than −2), and a neutral dielectric constant. A liquid crystal component containing a non-polar compound exhibiting anisotropy (Δε in a range of −2 or more and 2 or less) and a liquid crystal containing a compound showing a positive dielectric anisotropy of dielectric anisotropy (Δε is more than +2) And a nematic liquid crystal composition having a component.

In the liquid crystal display device according to the present invention, the first transient current I _p1 generated when a voltage is applied in homeotropic alignment state evaluation method and _the second transient current I _p2, the relationship between the rotational viscosity This will also be described below.

  It is known that the response speed of the liquid crystal display element depends on the viscosity of the liquid crystal composition. In particular, the rotational viscosity (hereinafter referred to as γ1) is an important material property value that determines the response time of the liquid crystal display element. As a method for measuring the rotational viscosity, a magnetic field application method in which a magnetic field is applied to a liquid crystal display element and a generated torque is measured has been mainstream. However, from the viewpoint that it takes a long time to measure and the device becomes large and it is difficult to evaluate the temperature dependence, a method for easily obtaining γ1 by measuring the transient current flowing in the liquid crystal cell is Imai. (Literature name: M. Imai et al: Jpn. Appl. Phys., 33, L119 1994). For example, Toyo Technica Co., Ltd. sells such a γ1 measuring device based on such transient current measurement as an LCM-2 type device, and this device is widely used as a γ1 measuring device in liquid crystal material manufacturers and liquid crystal panel manufacturers. ing.

In this specification, the transient current value I _p1 and the transient current value I _p2 are measured using an LCM-2 type apparatus (Toyo Technica Co., Ltd.).

  Here, an example of the γ1 measurement method using the LCM-2 type will be described. For example, when measuring γ1 of a liquid crystal composition having a negative dielectric anisotropy, an evaluation cell that is homeotropically aligned between the counter electrodes is used. In order to represent the state of the liquid crystal composition as much as possible, in order to represent the state of the liquid crystal composition as much as possible, the transient current at the time of γ1 measurement uses the capacitance change due to the change of the director of the liquid crystal molecules. It is desirable to use an evaluation cell having a cell gap that is so thick that it is not affected by the alignment regulating force. However, in the case of a thick cell gap, a high applied voltage is required to change the director. Specifically, a cell gap of about 5 to 20 μm is preferable, and an evaluation of a cell gap of 10 μm is preferable. A cell is preferred.

  A step voltage is applied while controlling the evaluation cell to a desired temperature. The measurement temperature depends on the measurement temperature of γ1 to be obtained, but since the change in transient current differs depending on the measurement temperature, the measurement temperature in this specification is 20 ° C. The step voltage indicates a waveform in which the voltage instantaneously changes at t = 0 seconds, and the magnitude of the transient current increases as the applied voltage increases. Furthermore, the applied width of the applied step voltage was 5 msec, and the applied polarity was positive. Further, the cut-off time of the measured inrush current was 10 μsec.

  It is known that the transient current at the time of measuring γ1 shows a change as shown in FIG. 11 if it is a normal nematic liquid crystal. When a step voltage is applied in γ1 measurement, a large inrush current flows first. This inrush current is a current value necessary for charging for the evaluation cell capacity. If the capacity is a normal evaluation cell capacity, the inrush current usually converges within 10 μsec. Thereafter, a transient current that flows due to a change in the capacitance accompanying the change in the director of the liquid crystal molecules is observed. It is known that this transient current has a single peak (Literature name: Journal of Liquid Crystal Society, Vol. 14, No. 2010).

  Since the transient current is caused by the rotation of the director, important knowledge is obtained about the electro-optical characteristics of the liquid crystal display element such as the reorientation process and response time of the director in the electric field response of the liquid crystal cell. (Literature name: Journal of Liquid Crystal Society, Vol. 14, No. 1, 2010).

Here, as a result of intensive studies by the inventors, a specific liquid crystal composition including a liquid crystal compound exhibiting positive dielectric anisotropy and a liquid crystal compound exhibiting negative dielectric anisotropy exhibits 2 It was found that there are two steps (the first (first) transient current is I _p1 and the second (second) transient current is I _p2 ). Further, the present inventors have found that it is possible to determine whether or not the liquid crystal composition can efficiently suppress flicker based on the magnitude relationship between the two steps of the transient current.

Specifically, it was found that when the first transient current I _p1 is larger than the second transient current I _p2 , the flicker suppression effect is high. This relationship is a phenomenon that can be observed in the case of a liquid crystal composition having a specific negative dielectric anisotropy to which a liquid crystal compound having a positive dielectric anisotropy is added. In addition, the phenomenon in which the peak values of the two transient currents occur and the first transient current I _p1 is larger than the second transient current I _p2 has a positive dielectric anisotropy. A liquid crystal compound having a large number of rings (for example, 4 rings or more, preferably 4 rings or more and 5 rings or less) having a positive dielectric anisotropy has a larger relaxation time. It is known to have a tendency to show.

  Next, the flicker rate for the liquid crystal display element according to the present invention will be described. When light transmitted through the liquid crystal display element is received by a photodiode or the like and this change in light intensity is analyzed as a change in the time direction using an oscilloscope or the like, a change in light intensity as shown in FIG. 13 is observed. The amplitude (fluctuation width) of the light intensity change represents flicker (light flicker). That is, it can be said that the larger the amplitude with respect to the average value of the light intensity, the larger the flicker. The flicker rate can be expressed by the following equation.

Flicker rate = amplitude / average brightness (%)
The flicker rate was measured using an n-type FFS mode panel. The n-type FFS panel has a line / space of 3 μm / 4 μm, an interlayer insulating film thickness of 500 nm, and a cell gap of 3.5 μm. The applied voltage was a rectangular wave with a frequency of 30 Hz, and the applied voltage was measured for a change in transmittance when a voltage corresponding to 23% was applied when the voltage indicating the maximum transmittance was 100%. Further, Compound A (Δε = 7.79, Δn = 0.10) or Compound B exhibiting positive dielectric anisotropy with respect to the reference liquid crystal composition (Δn = 0.11, Δε = -4.10). A composition in which the contents shown in Table 1 were respectively added (Δε = 7.88, Δn = 0.08) was manufactured, and the dielectric anisotropy and refractive index anisotropy of each composition were measured.

FIG. 12 and Table 1 show the results of evaluating the transient current changes (I _p1 and I _p2 ) and the flicker rate. According to this evaluation result, when the addition amount of the liquid crystal compound having a specific dielectric anisotropy is changed in the liquid crystal composition having a negative dielectric anisotropy, the first transient current I _It was found that _p1 becomes larger than the second (second time) transient current _Ip2 and the flicker rate becomes small.

  Therefore, the liquid crystal composition contained in the liquid crystal layer preferably includes a liquid crystal compound having a negative dielectric anisotropy and a liquid crystal compound having a positive dielectric anisotropy.

  The lower limit of the content of the liquid crystal compound having a positive dielectric anisotropy is related to the driving voltage of the liquid crystal layer, for example, 0.1% by mass or more, 0.3% by mass or more, 0.5% by mass. As mentioned above, 1 mass% or more, 3 mass% or more, 6 mass% or more, 8 mass% or more, and 10 mass% are preferable. The upper limit of the content of the liquid crystal compound having a positive dielectric anisotropy is related to the driving voltage of the liquid crystal layer, but is, for example, 25% by mass, 24% by mass, 23% by mass, 22% by mass or less. Is preferred.

  According to Table 1 below, it was confirmed that the addition of 10% of the liquid crystal compound having positive dielectric anisotropy can be reduced by 81% compared to the comparative example.

From these examination results, the transient current change of the liquid crystal composition is observed, and by comparing the magnitude relationship between the two transient currents I _p1 and I _p2 , the liquid crystal composition having a high flicker suppressing ability without producing a liquid crystal display element. Things can be easily identified. Moreover, in the liquid crystal display element using this liquid crystal composition, it is possible to provide a liquid crystal display element in which flicker is reduced as compared with the prior art.

  The present invention can be applied to liquid crystal display elements such as VA, PSVA, FFS and / or IPS. A method for reducing flicker caused by a decrease in the voltage holding ratio is desired in active driving such as VA, PSVA, FFS and / or IPS, particularly in low frequency driving. In addition, the FFS and IPS drive formats are more likely to cause reverse polarization and flicker because a strong electric field is applied to the liquid crystal when a voltage is applied, compared to the so-called VA mode. Therefore, a driving method of FFS and IPS is desired to reduce not only flicker caused by a decrease in voltage holding ratio but also flicker caused by reverse polarization as compared with VA and PSVA modes.

  Therefore, a preferred embodiment of the liquid crystal display element of the present invention has a liquid crystal layer and an alignment film layer for inducing homogeneous alignment between each of the first substrate and the second substrate, on the first substrate. A common electrode is arranged.

  In particular, since the FFS type display element generates a fringe electric field in the vicinity of the edge portion of the electrode, a particularly preferable aspect of the liquid crystal display element of the present invention is that the interelectrode distance: R between the pixel electrode and the common electrode is The distance between the first substrate and the second substrate is smaller than G, and a fringe electric field is formed between the pixel electrode and the common electrode.

1,8 Polarizing plate 2 First substrate 3 Electrode layer (first electrode)
3 'common electrode (second electrode)
4 alignment film 5 liquid crystal layer 6 color filter 7 second substrate 11 gate electrode 12 gate insulating film 13 semiconductor layer 14 insulating layer 15 ohmic contact layer 16 drain electrode 17 source electrode 18 insulating protective layer 19b source electrode 21 pixel electrode 22 common electrode 23 Storage Capacitor 24 Drain Electrode 25 Source Bus Line 26 Gate Bus Line 27 Source Electrode 28 Gate Electrode 29 Common Line

Claims (6)

A pair of substrates provided so that the first substrate and the second substrate are opposed to each other;
A liquid crystal layer sandwiched between the first substrate and the second substrate;
A pixel electrode provided on at least one of the first substrate and the second substrate;
A liquid crystal display element having a common electrode provided on at least one of the first substrate and the second substrate,
In the liquid crystal layer, when a first transient current value generated when a voltage is applied in a homeotropic alignment state is I _p1 and a second transient current value is I _p2 , the transient current value I _{p1 of the} liquid crystal layer A liquid crystal display element using a liquid crystal layer having a larger transient current value I _p2 of the liquid crystal.     The liquid crystal display element according to claim 1, wherein the pixel electrode and the common electrode are provided on the first substrate.     The liquid crystal display element according to claim 1, wherein the pixel electrode and the common electrode are provided on the first substrate, and the pixel electrode is provided on a liquid crystal side with respect to the common electrode.     The liquid crystal display element according to claim 1, wherein the pixel electrode and the common electrode are provided on the first substrate, and the common electrode is provided on a liquid crystal side with respect to the pixel electrode. A liquid crystal composition contained in a liquid crystal layer filled between electrode substrates,
A liquid crystal composition having a negative dielectric anisotropy, wherein a transient current value I _p1 generated first when a voltage is applied between the electrode substrates is larger than a transient current value I _p2 generated a second time.     The liquid crystal composition contained in the liquid crystal layer includes a liquid crystal compound having a negative dielectric anisotropy and a liquid crystal compound having a negative dielectric anisotropy according to claim 5, comprising a liquid crystal compound having a negative dielectric anisotropy and a liquid crystal compound having a positive dielectric anisotropy. Composition.

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