JP2007256453A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of displaying completely different patterns in one and the same display area or displaying a pattern which can be driven independently of an enclosing pattern. <P>SOLUTION: The liquid crystal display device 1 is constituted by stacking a back polarizing plate 2, a back liquid crystal cell 3 (first liquid crystal cell), a front liquid crystal cell 4 (2nd liquid crystal cell), and a front polarizing plate 5 in order. Both of the liquid crystal cells are TN type liquid crystal cells, and comprise a pair of transparent substrates 7a and 7b stuck together one over the other across a seal material 6, pairs of pattern electrodes 8a to 8d showing a display pattern, alignment layers 9a to 9d, and liquid crystal materials 10a and 10b. Both of the liquid crystal cells have common basic constitution, but the pattern electrodes 8a to 8d are in different shapes, rubbing directions of the alignment layers 9b and 9c are orthogonal to each other, and the liquid crystal materials 10a and 10b are twisted in opposite directions. Consequently, completely different patterns can be displayed in one and the same display area, and normally black display with a high contrast can be obtained. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a TN type liquid crystal display device using twisted nematic liquid crystal as a liquid crystal material.

  Conventionally, for example, a TN type (twisted nematic type) liquid crystal display device has been frequently used for a display indicating an operating state of an air conditioner or an audio device of a car. In addition, in a TN liquid crystal display device, a liquid crystal cell having a two-layer structure is known as a means for preventing so-called coloring (see Patent Document 1 below).

  A TN type liquid crystal display device having a two-layer structure disclosed in Patent Document 1 below is a TN type liquid crystal in which a pattern electrode is not provided on the surface of a normal TN type liquid crystal cell (drive cell) provided with a pattern electrode. The cell (compensation cell) is superposed. The driving cell and the compensation cell have the same retardation (product of the birefringence of the liquid crystal and the cell thickness), the twist angle of the liquid crystal material is the same, the directions are opposite, and the alignment films face each other. The orientation directions are orthogonal to each other. By adopting such a configuration, the interference color generated when the retardation of the liquid crystal display device is reduced is prevented, and the decrease in contrast is prevented.

  However, the liquid crystal display device disclosed in Patent Document 1 below can display only the pattern on the driving cell side while using two layers of liquid crystal cells. In addition, in a liquid crystal display device that performs segment display, when a plurality of functions are displayed on one liquid crystal screen, for example, segments such as numbers are shared, and segments provided for each function are different from each other. The display is performed by a driving method such as providing a selective display. For this reason, since there is no great difference in the display for each function, the display is often confusing and difficult to understand for the viewer.

  In addition, liquid crystal display devices are required to have a more flexible display mode due to recent diversification of user needs. The same applies to a liquid crystal display device that performs segment display. For example, there is a need for a display method for displaying and hiding independently of a surrounding pattern in a surrounding pattern such as a continuous circle or polygon.

However, in a liquid crystal display device that performs segment display, a routing electrode for applying a voltage for each segment is required. For this reason, in order to realize independent drive display in a surrounding pattern with a single liquid crystal cell, an insulating layer is provided on the surface of the surrounding display pattern electrode, and a pattern electrode in the surrounding pattern is provided on the surface of the insulating layer. Such a means is necessary, which increases the difficulty of manufacturing and increases the cost.
JP-A-57-125919

  An object of the present invention is to improve a liquid crystal display device, and more specifically, in order to eliminate the inconvenience, an object of the present invention is to provide a liquid crystal display device capable of displaying completely different patterns in the same display region. It is another object of the present invention to provide a liquid crystal display device capable of displaying a pattern that can be driven independently of a surrounding pattern even in a so-called surrounding pattern.

  In order to achieve the above object, a first aspect of a liquid crystal display device of the present invention includes a first liquid crystal cell and a second liquid crystal cell disposed so as to overlap the first liquid crystal cell. In the two-layer TN type liquid crystal display device in which the first and second liquid crystal cells are both TN type liquid crystals, the first liquid crystal cell and the second liquid crystal cell are arranged side by side through sealing materials, respectively. A pair of transparent substrates, a pair of pattern electrodes provided on the inner surface of the transparent substrate and showing a display pattern, a pair of alignment films provided on the inner surface of the pattern electrodes, and the sealing material and the interior of the alignment film are filled Liquid crystal material, the retardation of each is the same, the twist angle of the liquid crystal material is the same and the twist direction is opposite, the alignment directions of the alignment films facing each other are orthogonal, and each of the pattern electrodes is With its own pattern Made is characterized in that is.

  According to the liquid crystal display device of the first aspect, both the first liquid crystal cell and the second liquid crystal cell are provided with pattern electrodes, and each of the pattern electrodes has a unique pattern. When the liquid crystal cell is driven, the other liquid crystal cell becomes a compensation cell, and when the other liquid crystal cell is driven, one liquid crystal cell becomes a compensation cell. Therefore, two types of completely different displays can be performed in a single display region while maintaining high contrast as in the conventional two-layer TN type liquid crystal display device.

  In the liquid crystal display device according to the first aspect, when applying a voltage to one of the pattern electrodes of the first or second liquid crystal cell, a driving means is provided so as not to apply a voltage to the other. It is preferable to provide. Since each of the first and second liquid crystal cells has a unique pattern, there is a risk of erroneous display if they are displayed overlappingly. By preventing such erroneous display by the driving means, , Can always make a normal display.

  According to a second aspect of the liquid crystal display device of the present invention, the liquid crystal display device includes a first liquid crystal cell and a second liquid crystal cell disposed so as to overlap the first liquid crystal cell. In the two-layer TN type liquid crystal display device in which both of the liquid crystal cells are TN type liquid crystals, the first liquid crystal cell and the second liquid crystal cell each have a pair of transparent substrates arranged in parallel via a sealing material, A pair of pattern electrodes provided on the inner surface of the transparent substrate and showing a display pattern; a pair of alignment films provided on the inner surface of the pattern electrode; and a liquid crystal material filled in the sealing material and the alignment film. Each of the retardations is the same, the twist angles of the liquid crystal material are the same, the twist directions are opposite, the alignment directions of the alignment films facing each other are orthogonal, and the first and second liquid crystal cells are connected to the display surface. When viewed from one liquid crystal cell Around the vignetting pattern electrode, it characterized in that it is surrounded seamlessly by a pattern electrode provided on the other of the liquid crystal cell.

  According to the liquid crystal display device of the second aspect, since the pattern electrode surrounding the periphery of the pattern electrode provided in one of the first liquid crystal cell or the second liquid crystal cell is provided in the other liquid crystal cell, The pattern electrodes can be driven independently. Accordingly, it is possible to display a pattern that can be driven independently of the surrounding pattern even in the so-called surrounding pattern without newly providing an insulating layer or the like.

  In the liquid crystal display device of the second aspect, in the single drive mode in which voltage is applied to only one of the pattern electrodes of the first or second liquid crystal cell, or in the simultaneous drive mode in which voltage is applied to both. It is preferable to include a drive means that can be driven. By providing such a driving means, it is possible to combine the surrounding pattern and the pattern in the surrounding pattern and display only the surrounding pattern, display only the internal pattern, and simultaneously display both patterns. Thereby, it becomes possible to respond to various needs of users.

  Next, an example of an embodiment of the liquid crystal display device of the present invention will be described with reference to FIGS. FIG. 1 is an explanatory cross-sectional view showing a laminated structure of a liquid crystal display device as an example of an embodiment of the present invention, and FIGS. 2A to 2D are views showing a polarization direction and a rubbing direction in the liquid crystal display device of FIG. 3A is an explanatory view showing a display pattern of a rear liquid crystal cell, FIG. 3B is an explanatory view showing a display pattern of a front liquid crystal cell, and FIGS. 4A to 4C are second embodiments. It is explanatory drawing which shows the display mode of a form.

  First, a liquid crystal display device 1 according to a first embodiment of the present invention will be described with reference to FIGS. The liquid crystal display device 1 according to the first embodiment has a rear polarizing plate 2, a rear liquid crystal cell 3 (first liquid crystal cell), and a front liquid crystal cell 4 (second liquid crystal) from the back side to the front side (display side). The liquid crystal cell) and the front polarizing plate 5 are overlaid in this order.

  Both the back liquid crystal cell 3 and the front liquid crystal cell 4 are TN liquid crystal cells. As shown in FIG. 1, the configuration shows a pair of transparent substrates 7a, 7b and 7c, 7d, which are overlapped with each other via a sealant 6, and a display pattern provided on the inner surface side of the transparent substrates 7a, 7b. A pair of pattern electrodes 8a, 8b and 8c, 8d, a pair of alignment films 9a, 9b and 9c, 9d provided on the inner surface side of the pattern electrodes 8a to 8d, and liquid crystal materials 10a, 10b filled therein, Consists of. Although the rear liquid crystal cell 3 and the front liquid crystal cell 4 have the same basic configuration, the shape of the pattern electrodes 8a to 8d, the rubbing direction of the alignment films 9a to 9d, and the twist direction of the liquid crystal materials 10a and 10b Is different.

  As the transparent substrates 7a and 7b, commonly used glass substrates are used, which are provided with pattern electrodes 8a to 8d in which display patterns are formed on the inner surface when a liquid crystal cell is formed. I am using it. As for the display pattern, the rear liquid crystal cell 3 has the pattern shown in FIG. 3A, and the front liquid crystal cell 4 has the pattern shown in FIG. 3B. In this embodiment, the display which is provided in the instrument panel of a motor vehicle and shows the operating state of an air conditioner and the operating state of an audio device is taken as an example.

  Comparing FIGS. 3A and 3B, the graph display indicating the size and number of segments representing numbers, or the volume, etc., are formed in greatly different shapes. 3A and 3B, in addition to the illustrated display elements, segments of other display elements (for example, radio AM display) are not visible. Is not shown.

  The alignment films 9a to 9d are formed by forming a thin film on the surface on which the pattern electrodes 8a to 8d are provided and rubbing them in a predetermined direction shown in FIG. 2 using a rubbing cloth. As for the rubbing direction, when the reference direction in FIG. 2 is the vertical direction, as shown in FIG. 2 (b), the back side alignment film 9a of the back liquid crystal cell 3 is 45 ° above the left and the front side alignment film 9b is 45 ° left. It is down. Further, as shown in FIG. 2 (c), the back side alignment film 9c of the front liquid crystal cell 4 is 45 ° lower right and the front side alignment film 9d is 45 ° lower left. In the present embodiment, a low pretilt alignment film SE-410 manufactured by Nissan Chemical Industries, Ltd. is used as the alignment films 9a to 9d, and a rubbing cloth made of rayon is used.

  The rear polarizing plate 2 is formed so that its transmission axis is orthogonal to the rubbing direction of the rear side alignment film 9a of the rear liquid crystal cell 3, as shown in FIG. 2 (a). ) And (d), the front polarizing plate 5 is formed so as to be orthogonal to the transmission axis of the rear polarizing plate 2 and the rubbing direction of the front side alignment film 9d of the front liquid crystal cell 4. Thus, in this embodiment, the back polarizing plate 2 and the front polarizing plate 5 have a so-called crossed Nicols relationship.

  As for the liquid crystal materials 10a and 10b, the liquid crystal material 10a used for the back surface liquid crystal cell 3 and the liquid crystal material 10b used for the front surface liquid crystal cell 4 have the same birefringence and twist angle and the opposite twist directions. Specifically, a liquid crystal material manufactured by Merck Co., Ltd. having a birefringence Δn of 0.112 μm is used as the liquid crystal materials 10a and 10b. Further, 0.2% by weight of S-811, which is a left-handed chiral agent manufactured by the same company, is added to the liquid crystal material 10a of the rear liquid crystal cell 3, and a right-handed chiral agent is added to the liquid crystal material 10b of the front liquid crystal cell 4. 0.2% by weight of ZLI-3786 was added. Since these two chiral agents form isomers with each other, their molecular structure and chiral pitch are equal, and only the chiral direction is different. The twist angle is 90 ° due to the back alignment films 9a and 9b and the front alignment films 9c and 9d.

  Then, in both the back liquid crystal cell 3 and the front liquid crystal cell 4, the alignment films face each other and are overlapped with a seal material 6 and a gap control material (not shown) having a diameter of 4 μm interposed therebetween, and liquid crystal materials 10a and 10b are injected. Thus, a liquid crystal cell was formed. This gap control material is made of a transparent granular plastic material or the like having a uniform diameter, and keeps the distance between the substrates of the liquid crystal cell at a constant distance. Therefore, the cell thickness d is 4 μm for both the rear liquid crystal cell 3 and the front liquid crystal cell 4. Further, as shown in FIG. 1, the rear liquid crystal cell 3 and the front liquid crystal cell 4 were overlapped and fixed. At this time, as shown in FIGS. 2B and 2C, the alignment directions of the alignment films facing each other are orthogonal, that is, the rubbing direction of the front alignment film 9 b of the back liquid crystal cell 3 and the front liquid crystal cell 4. The back liquid crystal cell 3 and the front liquid crystal cell 4 were overlapped so that the rubbing direction of the back alignment film 9c was orthogonal.

  As described above, in the liquid crystal display device 1 of the first embodiment, the rear liquid crystal cell 3 and the front liquid crystal cell 4 both have a birefringence Δn of 0.112 μm and a cell thickness d of 4 μm. The retardation Δnd is both 0.448 μm.

  A controller 11 that controls display is connected to the pattern electrodes 8 a and 8 b of the rear liquid crystal cell 3 and the pattern electrodes 8 c and 8 d of the front liquid crystal cell 4. In this embodiment, the controller 11 is a control unit that performs display control of each part of the instrument panel of the automobile, and controls the display of the liquid crystal display device 1 according to an external command.

  Next, the operation of the liquid crystal display device 1 of the first embodiment will be described. FIG. 3A shows a state in which the frequency and volume of the FM radio are displayed on the liquid crystal display device 1. This display is performed by the controller 11 receiving current frequency and volume information from an FM radio (not shown) and applying a voltage to necessary segments in the pattern electrodes 8a and 8b of the rear liquid crystal cell 3. On the other hand, the controller 11 does not apply a voltage to the pattern electrodes 8 c and 8 d of the front liquid crystal cell 4.

  Next, when the driver gives a command to display the state of the air conditioner on the liquid crystal display device 1 using a changeover switch (not shown), the display on the liquid crystal display device 1 is switched to the display shown in FIG. . This display is performed by the controller 11 canceling the voltage applied to the pattern electrodes 8a and 8b of the rear liquid crystal cell 3 and applying the voltage to the necessary segments in the pattern electrodes 8c and 8d of the front liquid crystal cell 4. .

  In the present embodiment, the display pattern shown in FIGS. 3A and 3B is a completely black background normally black mode display, and a very high contrast display can be obtained. This is because in the liquid crystal display device 1 of the present embodiment, the rear liquid crystal cell 3 and the front liquid crystal cell 4 are in a relationship of optically compensating each other. In addition, both liquid crystal cells not only compensate each other but also have different display patterns, so that it is not restricted by the display pattern of the other liquid crystal cell and is optimal for display viewers. Can be displayed.

  Next, a second embodiment of the present invention will be described with reference to FIG. 1, FIG. 2, and FIG. As shown in FIGS. 4A to 4C, the liquid crystal display device 21 of the second embodiment displays a surrounding pattern 22 and an internal pattern 23 provided in the surrounding pattern 22. The second embodiment has a basic configuration in common with the first embodiment, and only the shape of the pattern electrodes 8a to 8d and the control method of the controller 11 are different. Therefore, the following description will be focused on the difference, and description of the same configuration will be omitted.

  In the second embodiment, the surrounding pattern 22 shown in FIG. 4B is displayed by the pattern electrodes 8a and 8b provided in the rear liquid crystal cell 3 shown in FIG. On the other hand, the internal pattern 23 shown in FIG. 4C is displayed by the pattern electrodes 8c and 8d provided in the front liquid crystal cell 4 shown in FIG.

  The controller 11 has two types, a single drive mode for driving only the pattern electrodes 8a and 8b of the rear liquid crystal cell 3 or the pattern electrodes 8c and 8d of the front liquid crystal cell 4, and a simultaneous drive mode for driving both pattern electrodes 8a to 8d. The liquid crystal display device 21 can be driven in this driving mode.

  Next, the operation in the liquid crystal display device 21 of the second embodiment will be described. For example, it is assumed that the display shown in FIG. 4C is a display displayed when the air conditioner in the manual mode is operated, and the display shown in FIG. 4A is a display displayed when the auto air conditioner is operated. When the driver operates the air conditioner in the manual mode, the controller 11 applies a voltage only to the pattern electrodes 8c and 8d of the front liquid crystal cell 4, and does not apply a voltage to the pattern electrodes 8a and 8b of the rear liquid crystal cell 3. The liquid crystal display device 1 is controlled by the single drive mode. As a result, as shown in FIG. 4C, only the characters “A / C” of the internal pattern 23 are displayed.

  Next, when the driver sets the air conditioner to an automatic air conditioner, the controller 11 applies a voltage to both the pattern electrodes 8a and 8b of the rear liquid crystal cell 3 and the pattern electrodes 8c and 8d of the front liquid crystal cell 4. Thus, the liquid crystal display device 1 is controlled. As a result, as shown in FIG. 4A, both the surrounding pattern 22 and the internal pattern 23 are displayed, and the surrounding square pattern is also displayed together with the characters “A / C”.

  Further, for example, in the operation of the automatic air conditioner, when the rapid operation mode is entered when the difference between the set temperature and the in-vehicle temperature is equal to or greater than a predetermined threshold value, the displays in FIGS. 4A and 4C may be alternately repeated. . In this case, the character “A / C” of the internal pattern 23 is lit and the surrounding pattern 22 is blinking. Alternatively, the display of FIGS. 4A and 4B may be alternately repeated. In this case, the surrounding pattern 22 is lit and the characters “A / C” of the internal pattern 23 are blinking.

  As described above, according to the liquid crystal display device 1 of the second embodiment, the surrounding pattern 22 and the internal pattern 23 can be driven independently or simultaneously, which is difficult in the conventional liquid crystal display device. Thus, independent driving of the internal pattern in the enclosed pattern can be realized. In addition, since the display does not require an additional step such as providing an insulating layer, the display can be easily performed.

  In the first embodiment, the pattern shown in FIG. 3A is displayed on the rear liquid crystal cell 3 and the pattern shown in FIG. 3B is displayed on the front liquid crystal cell 4. Good. Moreover, in the said 2nd Embodiment, although the surrounding pattern 22 of FIG.4 (b) is displayed on the back surface liquid crystal cell 3, and the internal pattern 23 of FIG.4 (c) is displayed on the front surface liquid crystal cell 4, The reverse is also possible. Moreover, in the said 2nd Embodiment, although the surrounding pattern 22 is made into the square, it is not restricted to this, If it surrounds the circumference | surroundings of the internal pattern 23, it can be set as arbitrary shapes. Moreover, in the said 2nd Embodiment, although the internal pattern 23 is made into the single display, it is not restricted to this, For example, it can be set as the variable number display using 7 segments.

  In each of the above embodiments, the twist angle of the TN liquid crystal is 90 °. However, the present invention is not limited to this, and a twist angle of 70 ° to 120 ° can be used. In this case, in the rear liquid crystal cell 3 and the front liquid crystal cell 4, the twist angles of the liquid crystal materials 10a and 10b are reversed, the retardation of both the liquid crystal cells 3 and 4 is common, and the alignment films 9b and 9c facing each other. What is necessary is just to make an orientation direction orthogonal.

  In each of the above embodiments, the display of normally black mode has been described. However, normally white mode display is performed in a so-called parallel Nicol relationship in which the polarization directions of the rear polarizing plate 2 and the front polarizing plate 5 are the same. May be. Further, the polarization direction of the back polarizing plate 2 and the rubbing direction of the back side alignment film 9a of the back liquid crystal cell 3 are orthogonal to each other, and the polarization direction of the front polarizing plate 5 and the rubbing direction of the front side alignment film 9d of the front liquid crystal cell 4 are Are orthogonal to each other. However, the present invention is not limited to this, and they may be parallel to each other.

  In each of the above embodiments, the back liquid crystal cell 3 and the front liquid crystal cell 4 are formed separately. However, as in Patent Document 1, the transparent substrate 7b of the back liquid crystal cell 3 and the front liquid crystal cell 4 are formed. The transparent substrate 7c may be shared to form a single transparent substrate. Moreover, the display pattern in each said embodiment is an illustration, and it can apply widely corresponding not only to the display in a motor vehicle but to household appliances and other products.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory sectional view showing a laminated structure of a liquid crystal display device which is an example of an embodiment of the present invention. (A)-(d) is explanatory drawing which shows the polarization direction and rubbing direction in the liquid crystal display device of FIG. (A) is explanatory drawing which shows the display pattern of a back surface liquid crystal cell, (b) is explanatory drawing which shows the display pattern of a front surface liquid crystal cell. (A)-(c) is explanatory drawing which shows the display mode of 2nd Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,21 ... Liquid crystal display device, 3 ... Back surface liquid crystal cell (1st liquid crystal cell), 4 ... Front surface liquid crystal cell (2nd liquid crystal cell), 6 ... Sealing material, 7a-d ... Transparent substrate, 8a-d ... Pattern electrodes, 9a to d, alignment films, 10a, b, liquid crystal materials.

Claims (4)

A two-layer TN type having a first liquid crystal cell and a second liquid crystal cell disposed so as to overlap with the first liquid crystal cell, wherein both the first and second liquid crystal cells are TN type liquid crystal In liquid crystal display devices,
Each of the first liquid crystal cell and the second liquid crystal cell includes a pair of transparent substrates arranged in parallel via a sealing material, a pair of pattern electrodes provided on an inner surface of the transparent substrate and indicating a display pattern, and the pattern A pair of alignment films provided on the inner surface of the electrode, and a liquid crystal material filled in the sealing material and the alignment film,
Each retardation is the same, the twist angle of the liquid crystal material is the same, the twist direction is opposite, the alignment directions of the alignment films facing each other are orthogonal, and each of the pattern electrodes is configured with a unique pattern A liquid crystal display device characterized by the above.   2. The driving device according to claim 1, further comprising: a driving unit configured not to apply a voltage to the other when applying a voltage to one of the pattern electrodes of the first or second liquid crystal cell. Liquid crystal display device. A two-layer TN type having a first liquid crystal cell and a second liquid crystal cell disposed so as to overlap with the first liquid crystal cell, wherein both the first and second liquid crystal cells are TN type liquid crystal In liquid crystal display devices,
Each of the first liquid crystal cell and the second liquid crystal cell includes a pair of transparent substrates arranged in parallel via a sealing material, a pair of pattern electrodes provided on an inner surface of the transparent substrate and indicating a display pattern, and the pattern A pair of alignment films provided on the inner surface of the electrode, and a liquid crystal material filled in the sealing material and the alignment film,
Each retardation is the same, the twist angle of the liquid crystal material is the same and the twist direction is opposite, the alignment directions of the alignment films facing each other are orthogonal,
When the first and second liquid crystal cells are viewed from the display surface, the periphery of the pattern electrode provided in one liquid crystal cell is surrounded by the pattern electrode provided in the other liquid crystal cell without any breaks. A liquid crystal display device.   Drive means capable of driving in a single drive mode in which a voltage is applied to only one of the pattern electrodes of the first or second liquid crystal cell, or a simultaneous drive mode in which a voltage is applied to both of them is provided. The liquid crystal display device according to claim 3.

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