JP2015191006A - liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display element capable of reducing display unevenness when both of a static drive system and a duty drive system are mixed.SOLUTION: The liquid crystal display element includes: a liquid crystal layer 50 containing an antistatic agent; a pair of substrates 11 and 12 facing each other by sandwiching the liquid crystal layer 50 therebetween; a first electrode part 20; and a second electrode part 30. The liquid crystal display element performs display corresponding to a region of the liquid crystal layer 50 sandwiched by the first electrode part 20 which is applied with a drive voltage by a static drive system, and performs display corresponding to a region of the liquid crystal layer 50 sandwiched by the second electrode part 30 which is applied with a drive voltage by a duty drive system. The concentration of the antistatic agent in the liquid crystal layer 50 is equal to or less than 50 ppm, and the value of the drive voltage applied to the second electrode part 30 is 1.8 times or more and 2.5 times or less the threshold value which is a voltage changed by 10% in transmission rate.

Description

  The present invention relates to a liquid crystal display element.

  As a conventional liquid crystal display element, Patent Document 1 discloses that a display area is an area where display is performed by static drive (picture area of the same document) and an area where display is performed by duty drive (main display area of the same document). A divided liquid crystal display element is disclosed.

  Regardless of whether the driving methods are mixed as disclosed in Patent Document 1, there is a problem that the liquid crystal display element is liable to cause alignment defects of the liquid crystal when charged. In consideration of this problem, Patent Document 2 tried to prevent liquid crystal alignment defects due to charging by limiting the specific resistance of the liquid crystal sandwiched between a pair of substrates within a predetermined range. A liquid crystal display element is disclosed.

JP-A-8-234704 JP 2008-180923 A

  In the liquid crystal display element of mixed driving like the one disclosed in Patent Document 1, the on-voltage in static driving is higher than that in duty driving. Therefore, it is common to adjust the appearance of the display area between the two driving methods by increasing the ON voltage in the duty driving. It is assumed that an antistatic agent that lowers the specific resistance of the liquid crystal is added to the liquid crystal composition when the on-voltage in the duty drive is set high as described above. In this case, although charging can be prevented, the behavior of the liquid crystal when a voltage is applied is affected by the antistatic agent, and the orientation of the liquid crystal is disturbed. When switching from off to on, the display unevenness as shown in FIG. It will be visually recognized as Ir (unnecessary shadow-like display).

  In Patent Document 2, no consideration is given to the case where drive systems coexist, and a simple proportional relationship does not hold between the specific resistance of the liquid crystal and the amount of antistatic agent added. Therefore, the method disclosed in Patent Document 2 cannot be applied to a mixed drive liquid crystal display element as it is.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a liquid crystal display element capable of reducing display unevenness when both static and duty drive systems coexist.

In order to achieve the above object, the liquid crystal display element according to the present invention is
Among the display areas, a liquid crystal display element that displays a first display element by a static drive method in a predetermined area and displays a second display element by a duty drive system in an area different from the predetermined area,
A liquid crystal layer containing an antistatic agent;
A pair of substrates facing each other across the liquid crystal layer;
A first electrode portion provided on the liquid crystal layer side of each of the pair of substrates;
A second electrode portion provided on the liquid crystal layer side of each of the pair of substrates,
The first display element is displayed corresponding to a region of the liquid crystal layer sandwiched between the first electrode portions to which a driving voltage is applied by a static driving method,
The second display element is displayed corresponding to a region of the liquid crystal layer sandwiched between the second electrode portions to which a driving voltage is applied by a duty driving method,
The concentration of the antistatic agent in the liquid crystal layer is 50 ppm or less;
The value of the drive voltage applied to the second electrode unit is 1.8 times or more and 2.5 times or less of a threshold voltage that is a voltage at which the transmittance changes by 10%.
It is characterized by that.

  According to the present invention, display unevenness can be reduced when both static and duty drive systems coexist.

It is a top view of the liquid crystal display element which concerns on one Embodiment of this invention. It is an AA line schematic sectional drawing of the liquid crystal panel shown in FIG. It is the figure which showed the relationship between the dopant density | concentration of a liquid crystal, and specific resistance in the several liquid crystal display element from which a liquid crystal composition differs mutually. FIG. 4 is a graph showing the relationship between the dopant concentration and specific resistance of the liquid crystal shown in FIG. 3. It is the figure which described the display nonuniformity and appearance evaluation of a liquid crystal display element at the time of changing a drive voltage, (a) is a dopant concentration of 100 ppm, (b) is a dopant concentration of 50 ppm, (c) is a dopant. It is a figure which shows the time of density | concentration of 0 ppm. It is a figure which shows a display nonuniformity.

  An embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, a liquid crystal display element 100 according to an embodiment of the present invention includes a liquid crystal panel 1, a first drive unit 2, and a second drive unit 3 (in the figure, these are shown). The outline of is shown with a dotted line). These are housed in a housing 4 where the display area of the liquid crystal panel 1 can be viewed.

  The liquid crystal display element 100 performs display operation by the first drive unit 2 in a predetermined area (hereinafter, static display area S) of the display area, and is different from the static display area S (hereinafter, duty display area D). ), Display operation is performed by the second drive unit 3.

The liquid crystal panel 1 is a vertical alignment type (VA (Virtical Alignment) type) liquid crystal panel, and is configured as a negative display type.
As shown in FIG. 2, the liquid crystal panel 1 includes a pair of substrates 11 and 12, a first electrode unit 20, a second electrode unit 30, alignment films 41 and 42, an antistatic agent (hereinafter referred to as a dopant). And a liquid crystal layer 50 including polarizing plates 61 and 62.

  FIG. 2 is a schematic cross-sectional view taken along the line AA of the liquid crystal panel 1 shown in FIG. 1, and is a diagram schematically showing the first driving unit 2 and the second driving unit 3 together. In addition, hereinafter, in order to facilitate understanding of the configuration of the liquid crystal panel 1, each part will be described as appropriate with the user side (display side) of the liquid crystal display element 100 as the front side of the predetermined member and the opposite side as the back side.

  The substrates 11 and 12 are each formed of, for example, glass, plastic or the like transparently. The pair of substrates 11 and 12 are disposed to face each other with the liquid crystal layer 50 interposed therebetween. The substrate 11 is located on the front side of the liquid crystal layer 50, and the substrate 12 is located on the back side of the liquid crystal layer 50.

  The first electrode portion 20 and the second electrode portion 30 are each composed of an ITO (Indium Tin Oxide) film mainly composed of indium oxide, a π-conjugated polymer (for example, polythiophene), and the like, and transmit light. It is a transparent electrode.

The first electrode unit 20 corresponds to the static display region S, and includes a front side electrode 21 located on the front side of the liquid crystal layer 50 and a back side electrode 22 located on the back side of the liquid crystal layer 50. The front side electrode 21 is formed on the surface of the substrate 11 on the liquid crystal layer 50 side, and the back side electrode 22 is formed on the surface of the substrate 12 on the liquid crystal layer 50 side by a known method (sputtering, vapor deposition, etching, etc.). The front side electrode 21 is configured as a common electrode, and the back side electrode 22 is configured as a segment electrode.
The 1st electrode part 20 (front side electrode 21 and back side electrode 22) is electrically connected with the 1st drive part 2 by the well-known method.

  The first drive unit 2 includes, for example, a static drive IC (Integrated Circuit) mounted on a circuit board (not shown) located on the back side of the liquid crystal panel 1, and the first electrode unit 20 has a static drive method. The drive voltage is applied by

The second electrode unit 30 corresponds to the duty display area D and includes a front side electrode 31 located on the front side of the liquid crystal layer 50 and a back side electrode 32 located on the back side of the liquid crystal layer 50.
The front side electrode 31 is formed on the surface of the substrate 11 on the liquid crystal layer 50 side, and the back side electrode 32 is formed on the surface of the substrate 12 on the liquid crystal layer 50 side by a known method (sputtering, vapor deposition, etching, etc.). The front side electrode 31 is configured as a common electrode, and the back side electrode 32 is configured as a segment electrode.

  In the first electrode unit 20, the front electrode 21 may be configured as a segment electrode, and the back electrode 22 may be configured as a common electrode. Similarly, in the second electrode unit 30, the front electrode 31 may be configured as a segment electrode, and the back electrode 32 may be configured as a common electrode.

  The second electrode unit 30 (the front side electrode 31 and the back side electrode 32) is electrically connected to the second drive unit 3 by a known method.

  The second drive unit 3 is composed of, for example, a duty drive IC mounted on the circuit board (not shown) described above, and applies a drive voltage to the second electrode unit 30 by a duty drive (dynamic drive) method. . In the present embodiment, the first drive unit 2 and the second drive unit 3 are configured by separate ICs.

  The first drive unit 2 and the second drive unit 3 may be configured by a single custom IC capable of both static drive and duty drive. From the viewpoint of cost reduction and ease of design.

In the present embodiment, the driving voltage V _lcd applied to the second electrode unit 30 by the second driving unit 3 is “a threshold voltage V ₁₀ that is a voltage at which the transmittance of the liquid crystal display element 100 changes by 10%. .8 times to 2.5 times (1.8 V ₁₀ ≦ V _lcd ≦ 2.5 V ₁₀ ) ”(hereinafter referred to as Condition 1). How the condition 1 is found will be described later.

  Further, the drive waveform output from the second drive unit 3 to the second electrode unit 30 is preferably an A waveform that is converted into an alternating current at a time-division period. Furthermore, the frame frequency f of the drive waveform is preferably 200 Hz or more (f ≧ 200 Hz). This is because when the alternating frequency is increased in this way, the dopant contained in the liquid crystal layer 50 can be prevented from moving unnecessarily, and the display unevenness Ir due to alignment defects of liquid crystal molecules can be reduced. In the liquid crystal display element 100 according to the present embodiment, the drive voltage and the dopant concentration are set to suitable conditions as will be described later, and the display waveform Ir is further reduced by the drive waveform being an A waveform. It is possible.

  The front side electrode 21 and the back side electrode 22 constituting the first electrode unit 20 are each patterned in a predetermined shape. The liquid crystal display element 100 corresponds to the predetermined shape in a region where the front electrode 21 and the back electrode 22 overlap when viewed from the normal direction of the opposing surfaces of the substrate 11 and the substrate 12 (hereinafter referred to as the substrate normal direction). The displayed display element. Here, the display element is an element of an image displayed by the liquid crystal display element 100, and includes not only a figure but also a single element representing a symbol such as a character, a number, or an icon. The liquid crystal display element 100 transmits light in the region of the liquid crystal layer 50 sandwiched between the first electrode unit 20 to which the on-voltage is applied from the first driving unit 2 by the static driving method, and thereby enters the region. The corresponding display element is set to the display state (displayed approximately white).

  The configuration of the second electrode unit 30 is the same, and the liquid crystal display element 100 displays a display corresponding to the shape of the patterned electrode in a region where the front-side electrode 31 and the back-side electrode 32 overlap when viewed from the substrate normal direction. Display elements. The liquid crystal display element 100 transmits light in a region of the liquid crystal layer 50 sandwiched between the second electrode units 30 to which the on-voltage is applied from the second driving unit 3 by the duty driving method. The corresponding display element is set to the display state (displayed approximately white).

  In the liquid crystal display element 100, a region where the front side electrode 21 and the back side electrode 22 do not overlap, a region where the front side electrode 31 and the back side electrode 32 do not overlap, and a region where no on-voltage is applied as viewed from the normal direction of the substrate Is a substantially black background region 6 (see FIG. 1). As described above, the liquid crystal display element 100 is configured as a so-called negative display type (normally black mode) in which display elements are displayed in a substantially black background region 6 in a substantially white color.

  Hereinafter, a display element displayed in the static display area S corresponding to the first electrode unit 20 is a first display element, and a display element displayed in the duty display area D is corresponding to the second electrode unit 30. This will be described as the second display element.

  In the static display area S, as shown in FIG. 1, the liquid crystal display element 100 can display a three-digit numerical value in a so-called 7-segment format and a unit of “km / h”. In this example, the first display element 7 is a hexagonal segment, a character “k”, a symbol “/”, or the like.

  In the duty display area D, as shown in FIG. 1, the liquid crystal display element 100 can display a 6-digit numerical value in a 7-segment format, a unit of “km”, and a bar graph. In this example, the second display element 8 is a hexagonal segment, a character “k”, a rectangular figure constituting a bar graph, or the like.

  The alignment films 41 and 42 are vertical alignment films in contact with the liquid crystal layer 50, respectively, and are formed from, for example, polyimide by a known method (for example, flexographic printing). The alignment film 41 covers the front side electrodes 21 and 31 from the liquid crystal layer 50 side, and the alignment film 42 covers the back side electrodes 22 and 32 from the liquid crystal layer 50 side.

  The alignment film 41 is rubbed in a predetermined direction to form fine grooves. The alignment film 42 is rubbed in the direction opposite to the rubbing direction of the alignment film 41 to form fine grooves (so-called anti-parallel rubbing). The alignment films 41 and 42 subjected to the rubbing treatment in this way indicate the alignment direction of the liquid crystal molecules (the major axis direction of the liquid crystal molecules) when no voltage is applied to the liquid crystal layer 50, as the main surfaces of the substrates 11 and 12. The liquid crystal molecules are aligned so as to be substantially perpendicular to the liquid crystal layer 50 side (so-called monodomain alignment).

  The pretilt angle θp (angle formed by the substrates 11 and 12 and the major axis of the liquid crystal molecules) given to the liquid crystal molecules by the alignment film 41 and the alignment film 42 is set in a range of 89 ° or more and less than 90, for example. . In this range, the pretilt angle θp is preferably small to reduce the display unevenness Ir. This is because the alignment stability is increased. On the other hand, when the pretilt angle θp is set large (for example, when θp is 89.5 ° or more), steepness and contrast are increased. However, when the pretilt angle θp is increased, display unevenness Ir is likely to occur. In such a case, if the drive waveform is set to the A waveform and the frame frequency is increased (f ≧ 200 Hz) as described above, the display unevenness Ir can be reduced while maintaining good contrast.

  The liquid crystal layer 50 is sealed in a space formed by the substrate 11, the substrate 12, and a sealing material (not shown) that joins both substrates. The liquid crystal layer 50 is made of a liquid crystal material having a negative dielectric anisotropy Δε (Δε <0). Further, the layer thickness (cell gap) of the liquid crystal layer 50 is kept constant by a spacer (not shown). When a voltage equal to or higher than the threshold voltage is applied to the liquid crystal layer 50, the liquid crystal molecules that are aligned substantially vertically behave like falling down. When the ON voltage is applied, the liquid crystal molecules are substantially parallel to the main surfaces of the substrates 11 and 12.

  A dopant (antistatic agent) is added to the liquid crystal material (liquid crystal composition) constituting the liquid crystal layer 50. The dopant prevents charging by lowering the specific resistance of the liquid crystal. The dopant is a substance having conductivity, and is composed of a conductive polymer, an ionic compound, a strong electron accepting compound, or the like.

  The liquid crystal layer 50 of the present embodiment is configured to satisfy the condition (hereinafter referred to as condition 2) that “the dopant concentration in the liquid crystal material is 50 ppm or less”. How to find the condition 2 will be described later.

  The polarizing plates 61 and 62 emit light incident from one surface side from the other surface side as linearly polarized light along a transmission axis perpendicular to the absorption axis. As shown in FIG. 2, the polarizing plate 61 is located on the front side of the substrate 11, and the polarizing plate 62 is located on the back side of the substrate 12. The polarizing plate 61 and the polarizing plate 62 are arranged so that their absorption axes are orthogonal to each other when viewed from the normal direction of the substrate (orthogonal Nicol arrangement). Note that a backlight (not shown) is provided on the back side of the polarizing plate 62. The liquid crystal display element 100 performs transmissive display with light from a backlight.

In the liquid crystal display element 100, the off voltage is set to a value lower than the threshold voltage at which liquid crystal molecules start to fall. Therefore, even when an off voltage is applied to the liquid crystal layer 50, the liquid crystal molecules remain substantially vertically aligned. In this case, the polarization direction of the light emitted from the backlight and passing through the polarizing plate 62 is hardly changed by the liquid crystal layer 50. Therefore, most of the light transmitted through the liquid crystal layer 50 from the back side cannot pass through the polarizing plate 61 arranged in a relationship of crossed Nicols with the polarizing plate 62. Therefore, the display of the region to which the off voltage is applied is visually recognized as black (normally black mode).
On the other hand, when an ON voltage set higher than the threshold voltage is applied to the liquid crystal layer 50, the liquid crystal molecules in the region to which the ON voltage is applied behave so as to be substantially parallel to the main surfaces of the substrates 11 and 12. . Thereby, birefringence occurs in the light transmitted through the liquid crystal layer 50, the polarization direction of the light changes, and the light transmitted through the liquid crystal layer 50 from the back side is transmitted through the polarizing plate 61. Therefore, the region where the on-voltage is applied is in the transmissive display state.
In the duty display area D, the second drive unit 30 applies a pulse signal with a predetermined duty ratio to the front electrode 31 configured as a common electrode, and selects a selection signal to the back electrode 32 configured as a segment electrode. Supply. As a result, the drive voltage V _lcd is applied to the liquid crystal layer 50 corresponding to the display element to be selected indicated by the selection signal. Since the ON voltage V _ON which is the effective value of the drive voltage _Vlcd is set higher than the threshold voltage, the liquid crystal molecules behave like being tilted, and the display element (second display element 8) is in the transmissive display state ( Lighting state).

  From here, it will be described how the inventors of the present application found the conditions 1 and 2 described above.

As described in the problem, in the liquid crystal display element 100 in which both the static and duty drive methods are mixed, in order to match the appearance of the duty display region D with the static display region S, it is necessary to set the ON voltage in the duty drive high. . However, when the ON voltage in the duty drive is set high, the dopant (antistatic agent) hinders the behavior of the liquid crystal, and the display unevenness Ir as shown in FIG.
As a method for reducing such display unevenness Ir, the specific resistance of the liquid crystal layer 50 may be lowered. However, since the specific resistance of the liquid crystal layer 50 is not simply proportional to the dopant concentration, the present inventors have thought that it is necessary to find a suitable condition for the dopant concentration.

  Here, the dopant concentration [ppm] and the ratio of the liquid crystal display elements (liquid crystals LC1 to LC7 in the figure) having the same structure as the liquid crystal display element 100 described above but different in composition of the liquid crystal layer 50 are shown in FIG. The relationship with the resistance [Ωcm] is shown.

LCD LC1~LC7, as shown in FIG. 3, the combination of the dopant concentration and the threshold voltage _{V 10} is respectively different. The threshold voltage V ₁₀ denotes the voltage at which the transmittance of the liquid crystal display device is changed by 10%. For example, when attention is paid to the liquid crystals LC2, LC4, LC5, and LC6 having a common dopant concentration of 100 ppm, it can be seen that the specific resistance values of the liquid crystal layer 50 are different from each other. 4 is a graph showing the relationship between the dopant concentration and the specific resistance of the liquid crystal layer 50 in each of the liquid crystals LC1 to LC7 shown in FIG. As can be seen from FIG. 4, the dopant concentration and the specific resistance are not in a simple proportional relationship. For this reason, it is necessary to find a suitable condition for the dopant concentration.

Accordingly, the inventors of the present application prepared three types of liquid crystal display elements 100 in which the threshold voltage V ₁₀ is common with 3.0 V and the dopant concentration of the liquid crystal layer 50 is different. Then, after changing the driving voltage, the display unevenness and the like were evaluated visually. These driving conditions and evaluation results are shown in FIGS.

  FIG. 5A shows the evaluation results of the liquid crystal display element in which the dopant concentration is set to 100 ppm. FIG. 5B shows the evaluation result of the liquid crystal display element in which the dopant concentration is set to 50 ppm. Moreover, the evaluation result of the liquid crystal display element of the liquid crystal layer 50 (dopant concentration 0 ppm) which does not add a dopant to FIG.5 (c) is shown.

The inventors of the present application evaluated each liquid crystal display element by changing the drive voltage V _lcd between 5.0V and 8.0V every 0.5V. In this evaluation, the liquid crystal display element 100 was driven at 1/4 duty at 5.5V or more. Further, when the drive voltage V _lcd is 5.0 V, the liquid crystal display element 100 is driven by the static drive method.

  The meanings of the evaluation results “◎”, “◯”, “Δ”, and “×” regarding the display unevenness and appearance described in FIGS. 5A to 5C are as follows.

(About display unevenness)
A: Not visually recognized in the specified temperature range (-30 ° C to 80 ° C).
◯: Although slightly visible at high temperature (above 60 ° C.), it is not visually recognized below room temperature (about 60 ° C.).
Δ: Visible at room temperature but acceptable.
X: Display unevenness is conspicuous.

(About appearance)
A: Bright when on and no problem with response speed.
○: It is slightly dark when on, but it is possible to supplement the brightness with the backlight. There is a slight delay in response speed at low temperatures (about -20 ° C).
(Triangle | delta): Dark at the time of ON is permissible. Response speed is delayed at low temperatures.
×: Display element is dark and difficult to see when on. Delay in response speed at low temperatures is unacceptable.

  Under the above conditions, first, attention is paid to the appearance of each liquid crystal display element shown in FIGS. 5 (a) to 5 (c). As shown in the figure, it can be seen that the appearance due to the brightness at the time of display and the response performance of the display does not change depending on the difference in dopant concentration.

Next, attention is focused on display unevenness of each liquid crystal display element.
As the dopant concentration is increased, the antistatic performance is naturally improved. However, as can be seen from FIGS. 5A to 5C, as the dopant concentration is increased, the behavior of the liquid crystal at the time of voltage application is influenced by the dopant. And display unevenness is likely to occur. Therefore, it is necessary to find a suitable relationship between the dopant concentration and the drive voltage V _lcd .

(Dopant concentration: 100 ppm)
Consider a liquid crystal display device in which the dopant concentration in FIG.
When V _lcd is 5.0 V, the evaluation for display unevenness is very good as “◎”. However, in this case, since it is a static drive, it cannot be adopted as a condition for the duty display area D in the first place. Also, the appearance is bad with “×”.
When V _lcd is 5.5V, the evaluation for display unevenness is “Δ”. However, in this case, since the appearance is “Δ” and the display becomes dark, it is not possible to adopt the condition for the duty display region D in consideration of the difficulty in matching the display brightness of the static display region S.
When V _lcd is 6.0 V or more, the evaluation for the display unevenness is not acceptable as “x”.
Considering the above, it can be said that it is not preferable to set the dopant concentration to 100 ppm in the mixed drive liquid crystal display element 100.

(Dopant concentration: 50 ppm)
Consider a liquid crystal display device in which the dopant concentration in FIG. 5B is set to 50 ppm.
When V _lcd is 5.0 V, the evaluation for display unevenness is very good as “◎”. However, in this case, since it is a static drive, it cannot be adopted as a condition for the duty display area D in the first place. Also, the appearance is bad with “×”.
When V _lcd is 5.5 V, the evaluation for display unevenness is very good as “◎”. As the drive voltage is increased from 5.5V to 7.5V, the behavior of the liquid crystal during voltage application is likely to be affected by the dopant, and the display unevenness gradually becomes visible. Even in the case of 7.5V, the evaluation is “Δ” and the allowable range. Further, as the drive voltage is increased from 5.5V to 7.5V, the brightness and responsiveness can be increased, so that the appearance of the liquid crystal display element is improved.
Considering the mutual relationship between the display unevenness and the appearance, it can be seen that V _lcd is preferably 5.5 V to 7.5 V.

In this evaluation, but the threshold voltage V ₁₀ is a liquid crystal display element of 3.0 V, not naturally threshold voltage limited to this value. Therefore, considering that the drive voltage V _lcd to be applied to the second electrode unit 30 is increased or decreased in accordance with the increase or decrease of the threshold voltage, the drive voltage V _lcd is 1.8 times or more the threshold voltage V ₁₀ . If it is set within a range of 5 times or less, it can be said that it is suitable for reducing display unevenness while maintaining good appearance. In this way, the inventors of the present application found the condition 1 described above.

Furthermore, as shown in FIG. 5B, it can be seen that when V _lcd is 6.0 V and 6.5 V, the balance between display unevenness and appearance is suitable. Therefore, if not only reduction of display unevenness but also good appearance is desired, V _lcd is preferably 6.0 V or more and less than 7.0 V. In this case as well, considering that the drive voltage V _lcd to be applied to the second electrode unit 30 is also increased or decreased in accordance with the increase or decrease of the threshold voltage, the drive voltage V _lcd is more than twice the threshold voltage V _10. It can be said that it is preferable to set it within a range of 2.3 times or less.

(Dopant concentration is 0ppm)
Consider a liquid crystal display device in which the dopant concentration of FIG. 5C is set to 0 ppm (that is, no dopant added).
Note that the liquid crystal layer 50 of this embodiment contains a dopant, and if the concentration of the dopant considered earlier is lower than that when the concentration is 50 ppm, the amount of dopant that adversely affects the behavior of the liquid crystal molecules is reduced, so that display unevenness is reduced. It is assumed that it will be done, but will be considered here for confirmation.

Referring to FIG. 5C, if the drive voltage V _lcd is within the range of the condition 1 found above, the display unevenness can be reduced as expected, and the display unevenness is lower than when the dopant concentration is 50 ppm. It can be seen that the reduction effect is good. However, in the case of the dopant additive-free, if V _lcd is 8.0V is an evaluation of display unevenness "×", if V _lcd is 5.0V is an evaluation of appearance "×", unacceptable .
From this, even when the dopant concentration is 50 ppm or less and greater than 0 ppm, it can be seen that the above condition 1 is essential to reduce display unevenness. At the same time, it can be found that the optimum range of the dopant concentration is the condition 2 that “the dopant concentration is 50 ppm or less”.

  Since the liquid crystal display element 100 satisfies the conditions 1 and 2 derived as described above, the display unevenness Ir can be reduced.

  In addition, this invention is not limited by said embodiment and drawing. Of course, changes (including deletion of components) can be added to these.

  The example in which the liquid crystal display element 100 is the VA type and the negative display type (normally black mode) has been described above, but the present invention is not limited thereto. The liquid crystal display element may be a TN (Twisted Nematic) type or the like, or may be a positive display type (normally white mode) in which display elements are displayed in a substantially black background area.

  In the above, an example in which the liquid crystal display element 100 displays the display elements in the segment format in the duty display region D has been shown, but the display elements may be displayed in the passive matrix format. In this case, one pixel (dot) or a set of a plurality of pixels corresponds to the second display element 8.

  In the above description, in order to facilitate the understanding of the present invention, the description of known unimportant technical matters is appropriately omitted.

DESCRIPTION OF SYMBOLS 100 ... Liquid crystal display element 1 ... Liquid crystal panel 2 ... 1st drive part 3 ... 2nd drive part S ... Static display area 7 ... 1st display element D ... Duty display area 8 ... 2nd display element 11, 12 DESCRIPTION OF SYMBOLS ... Substrate 20 ... 1st electrode part 21 ... Front side electrode 22 ... Back side electrode 30 ... 2nd electrode part 31 ... Front side electrode 32 ... Back side electrode 41, 42 ... Orientation film 50 ... Liquid crystal layer 61, 62 ... Polarizing plate

Claims (5)

Among the display areas, a liquid crystal display element that displays a first display element by a static drive method in a predetermined area and displays a second display element by a duty drive system in an area different from the predetermined area,
A liquid crystal layer containing an antistatic agent;
A pair of substrates facing each other across the liquid crystal layer;
A first electrode portion provided on the liquid crystal layer side of each of the pair of substrates;
A second electrode portion provided on the liquid crystal layer side of each of the pair of substrates,
The first display element is displayed corresponding to a region of the liquid crystal layer sandwiched between the first electrode portions to which a driving voltage is applied by a static driving method,
The second display element is displayed corresponding to a region of the liquid crystal layer sandwiched between the second electrode portions to which a driving voltage is applied by a duty driving method,
The concentration of the antistatic agent in the liquid crystal layer is 50 ppm or less;
The value of the drive voltage applied to the second electrode unit is 1.8 times or more and 2.5 times or less of a threshold voltage that is a voltage at which the transmittance changes by 10%.
The liquid crystal display element characterized by the above-mentioned. The value of the drive voltage applied to the second electrode unit is at least twice the threshold voltage.
The liquid crystal display element according to claim 1. The value of the drive voltage applied to the second electrode is not more than 2.3 times the threshold voltage.
The liquid crystal display element according to claim 1 or 2. A first driving unit that applies a voltage to the first electrode unit by a static driving method; and a second driving unit that applies a voltage to the second electrode unit by a duty driving method;
The first drive unit and the second drive unit are configured by separate ICs (Integrated Circuits).
The liquid crystal display element according to claim 1, wherein the liquid crystal display element is a liquid crystal display element. It is a VA (Virtical Alignment) type and is a negative display type that transparently displays the first display element and the second display element.
The liquid crystal display element according to claim 1, wherein the liquid crystal display element is a liquid crystal display element.