JP3607270B2 - Terminal device and portable terminal device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it difficult to recognize displayed contents from directions other than that from the front of a liquid crystal display device and to display a figure or a trade name or the like by utilizing the fact that a fixed pattern is viewed when viewing from the directions other than that from the front. <P>SOLUTION: The terminal device comprises: a liquid crystal layer; an alignment layer orientating the liquid crystal layer; and a driving circuit driving the liquid layer. The alignment layer is divided into a plurality of specified regions, each having a recognizable size. The orientation directions of adjacent regions are different from each other. <P>COPYRIGHT: (C)2003,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a terminal device and a mobile terminal device.
[0002]
[Prior art]
In recent years, liquid crystal display devices have been increased in size, and the market has expanded as display devices for notebook computers and monitors.
[0003]
Conventionally, a commonly used TN liquid crystal display device has a problem that the contrast is largely dependent on the viewing angle, and the display cannot be seen from a specific direction. However, in recent years, this point has been improved by using a viewing angle compensation film or the like. The liquid crystal display device can also have the same viewing angle as that of the CRT.
[0004]
As a method for widening the viewing angle, USP 5,666,178 and USP 5,652,634 have disclosed a device for providing a plurality of portions having different pretilt angles in one pixel in order to widen the viewing angle, thereby widening the viewing angle. Japanese Patent Application Laid-Open No. 9-5766 discloses one in which portions having different pretilt angles are provided in one picture element. These prior arts provide a portion having a different pretilt angle in one pixel for the purpose of widening the viewing angle.
[0005]
In this method of widening the viewing angle, color unevenness or the like is not generated in the screen, so that the ratio of the portions having different pretilt angles in one pixel is constant over the entire screen.
[0006]
In addition, Japanese Patent Application Laid-Open No. 61-51124 and Japanese Patent Application Laid-Open No. 61-51125 disclose a display pattern on a substrate having a different orientation direction for each display pattern. Here, a direction that is easy to see / a direction that is difficult to see is provided for each display pattern, and a display pattern that can be seen from one direction and a display pattern that cannot be seen are generated, so that at least one display pattern can be seen from multiple directions.
[0007]
On the other hand, there is also a demand for a display that can be viewed only from the front and cannot be viewed from an oblique direction, mainly for applications such as portable terminals. This is to prevent this information from being seen by anyone other than the user of the display when creating or reading a confidential document or the like in a public place. Moreover, it is for reading and writing a personal e-mail etc. without worrying about the surroundings. This technique is referred to herein as a “narrow viewing angle reduction technique”.
[0008]
Up to now, as a technique for narrowing the viewing angle, a method using a liquid crystal display device having both a liquid crystal layer for image display and a liquid crystal layer for phase difference control (JP-A-11-174489, JP-A-11-7045, JP-A-9-90). 105958), those using a lens sheet (Japanese Patent Laid-Open No. 11-84357 and others), and those using a diffusion light guide plate (Japanese Patent Laid-Open No. 10-97199 and others).
[0009]
[Problems to be solved by the invention]
As described above, the conventional narrow viewing angle technology has problems such as an increase in the number of members and a reduction in the viewing angle.
[0010]
[Means for Solving the Problems]
Accordingly, the present invention provides a display device that displays a fixed image that is not different from a normal liquid crystal display device from the front and that is not linked to a video signal input from a specific direction.
[0011]
The liquid crystal display device of the present invention comprises a liquid crystal layer and an alignment film sandwiching the liquid crystal layer, and the alignment film is, Multiple in pixelsPartitioned into areas containing pixels,Within the region, the orientation direction is the same, andIt is characterized in that the alignment directions of the adjacent regions are different.
[0012]
The area may be a character. Here, the character may be a character string or a message character string.
[0013]
The area may be a visual figure. Here, visual inspection is a figure having a size that can be visually recognized with the naked eye. It is also possible to include characters.
[0014]
The long side of the smallest rectangle (including a square) that includes the region is preferably 0.1 mm or more. That is, when the long side of the rectangle is about 0.1 mm or more, the display screen is difficult to visually recognize from directions other than the front.
[0015]
The area may be square.
[0016]
The maximum value of the driving voltage for driving the liquid crystal layer can be less than the saturation voltage of the liquid crystal layer.
[0017]
The maximum value of the driving voltage for driving the liquid crystal layer may be 0.5% to 70% of the saturation voltage of the liquid crystal layer.
[0018]
In particular, in the normally white system, the driving voltage for driving the liquid crystal layer may be 0.5% to 70% of the saturation voltage of the liquid crystal layer. In the normally black method, the maximum value of the driving voltage for driving the liquid crystal layer may be 70% or less of the saturation voltage of the liquid crystal layer.
[0019]
Within the region, the same color pixels may have the same orientation direction.
[0020]
The liquid crystal display device of the present invention includes a liquid crystal layer and an alignment film sandwiching the liquid crystal layer, and the alignment film has a plurality of alignment directions different from each other.VisibilityDivided into areas,Within the region, the orientation direction is the same,The area ratio of the region in at least one pixel may be different from the area ratio of the region in other pixels. That is, when a plurality of regions exist on one pixel, the area ratio of the regions is made different for a part of all the pixels on the screen. However, the same area ratio for all pixels corresponds to the conventional wide viewing angle, and a fixed image cannot be displayed.
[0021]
The area may be a character.
[0022]
The area may be a visual figure.
[0023]
The liquid crystal display device of the present invention further includes a liquid crystal layer, an alignment film sandwiching the liquid crystal layer, and a driving unit that drives the liquid crystal layer, and displays an image by the driving unit on the front surface of the liquid crystal layer. In addition, a fixed image independent of the driving unit may be displayed on a portion other than the front surface.
[0024]
The alignment film may include a plurality of regions having different alignment directions.
[0025]
The fixed image may be a character.
[0026]
The fixed image may be a visual figure.
[0027]
The fixed image may have a color.
[0028]
In addition, the liquid crystal display device of the present invention includes a liquid crystal layer, an alignment film that sandwiches the liquid crystal layer, and a drive unit that drives the liquid crystal layer, and the normal direction of the liquid crystal layer depends on the drive unit. An image may be displayed, and a fixed image independent of the driving unit may be displayed in a predetermined direction other than the normal direction.
[0029]
The liquid crystal display device of the present invention includes a first liquid crystal layer that performs image display based on an input signal, a second liquid crystal layer, and an alignment film that sandwiches the second liquid crystal layer, and the alignment film is visible. It may be divided into a plurality of regions composed of figures, and the orientation directions of the adjacent regions may be different.
[0030]
The liquid crystal display device of the present invention comprises a liquid crystal layer, a substrate sandwiching the liquid crystal layer, and a driving means for driving the liquid crystal layer, and displays an image by the driving means on the front surface of the liquid crystal layer, A fixed image independent of the driving means may be displayed on the screen other than the front surface.
[0031]
The terminal device according to the present invention includes a liquid crystal layer, an alignment film sandwiching the liquid crystal layer, and a drive unit that drives the liquid crystal layer, and displays an image by the drive unit on the front surface of the liquid crystal layer, Other than the front surface, a liquid crystal screen for displaying a fixed image independent of the driving means can be provided.
[0032]
The portable terminal device according to the present invention includes a liquid crystal layer, an alignment film sandwiching the liquid crystal layer, and a driving unit that drives the liquid crystal layer, and an image by the driving unit is displayed on the front of the liquid crystal layer. A liquid crystal screen for displaying and displaying a fixed image independent of the driving means other than the front can be provided.
[0033]
According to the present invention, the alignment film of the liquid crystal display device is divided into a plurality of regions, and when the screen is viewed from a specific direction by changing the alignment direction in each region, some regions are black or black. Make it visible in other colors. This applies to the fact that the viewing angle of the liquid crystal display varies depending on the alignment treatment direction on the alignment film.
[0034]
In this way, since a part of the region looks like a fixed color from the specific direction, it is possible to prevent the screen from being viewed from the specific direction.
[0035]
In addition, a fixed image can be viewed from a specific direction independently of display of an image signal input to the liquid crystal display device.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to these embodiments. Moreover, numerical values such as thickness, materials, and the like are examples.
(First embodiment)
A first embodiment of the present invention will be described. In this embodiment, the alignment film is partitioned into a plurality of square regions. Within this square region, there is one orientation direction, but in the adjacent square regions, the orientation direction is changed, and a plurality of types of orientation directions are periodically repeated.
[0037]
FIG. 1 is a cross-sectional view of the liquid crystal display device of this embodiment. This cross-sectional view is cited for explaining the general structure of the liquid crystal display device, and the following embodiments are not limited to this structure.
[0038]
A polyimide alignment film 13 is provided on a glass substrate 11 on which a thin film transistor (TFT) is formed. On the other hand, a polyimide alignment film 14 is provided on the glass substrate 12 on which the color filter is formed. A liquid crystal material 15 is sealed between the glass substrate 11 and the glass substrate 12. A spacer 16 having a particle size of about 5 μm is inserted between the glass substrate 11 and the glass substrate 12. Further, the end portion of the glass substrate is sealed with an epoxy sealant 17. In this way, a liquid crystal display device having a uniform thickness is obtained. A method of keeping the distance between the glass substrate 11 and the glass substrate 12 may be by providing a column on the substrate in addition to the spacer 16. In the case of a small display, the interval may be maintained only by the sealing material 17 at the end of the glass substrate.
[0039]
A driving device for driving the liquid crystal layer is connected to the upper and lower substrates sandwiching the liquid crystal layer. This driving device may connect a driving circuit or the like to the glass substrate 11 or the glass substrate 12, but may be provided on the glass substrate 11 or the glass substrate 12.
[0040]
As the liquid crystal material, TN liquid crystal LIXON 5010 manufactured by Chisso Petrochemical Co., Ltd., which is used as a TN liquid crystal material, can be used.
[0041]
As the alignment film, polyimide PI-1051 for alignment film manufactured by Nippon Synthetic Rubber Co., Ltd. can be used.
[0042]
FIG. 2 shows a plan view of the liquid crystal display device according to the present embodiment. Hereinafter, although the notation of an upper substrate and a lower substrate is used, one of the glass substrate 11 provided with TFTs and the glass substrate 12 provided with color filters is called an upper substrate, and the other is called a lower substrate.
[0043]
The alignment film is subjected to alignment treatment so that regions having two alignment directions a and b as shown in FIG. 2 are alternately arranged. Here, the alignment process is, for example, a rubbing process.
[0044]
By this alignment process, the screen is divided into two types of small areas a and b. Each of these regions is, for example, a square having a side of about 2.5 mm. This small area is sufficiently large compared to the pixel and is large enough to directly recognize the area.
[0045]
The rubbing process is performed as follows in this embodiment. First, a polyimide film is formed on the lower substrate, and a uniform rubbing process is performed on the entire surface of the polyimide film.
[0046]
Next, a region to be either a or b is covered with a stainless steel metal thin film as shown in FIG. 17, for example. Here, the region b is covered, a rubbing process in the reverse direction is performed from above, and the metal thin film is removed, whereby a substrate as shown in FIG. 2 is formed.
[0047]
A polyimide film is formed on the entire surface of the upper substrate facing FIG. 2 as well as the lower substrate. Thereafter, the entire surface of the polyimide film is rubbed so as to be perpendicular to the rubbing direction performed on the lower substrate when facing each other. And the area | region corresponding to either one of a lower board | substrate is covered with the metal thin film made from stainless steel. Here, a rubbing process is performed so as to cover the region b and from above, in a direction perpendicular to that performed on the lower substrate and this time in a direction opposite to the region b. Thereafter, the metal thin film is removed.
[0048]
As shown in FIG. 3, the orientation processing direction of the region a and the region b is a solid arrow direction on the lower substrate, and is opposite in the regions a and b. Here, it is the direction of the dotted arrow on the upper substrate, and the reverse direction is in regions a and b. Further, the squares of the upper substrate and the lower substrate are arranged opposite to each other so that the orientation directions of the upper substrate and the lower substrate are vertical in the regions a and b.
[0049]
In the liquid crystal display device of this embodiment, a polarizing plate is provided on the surfaces of the upper and lower substrates. Here, the polarizing directions of the polarizing plates of the upper and lower substrates are set parallel to each other so that black display is achieved when no voltage is applied, and further, the rubbing direction is set to be parallel to one of the regions a and b.
[0050]
In addition, the maximum voltage used for driving is set to about 70% of the saturation voltage of the liquid crystal. In view of display quality, the maximum voltage is preferably about 70% or less of the saturation voltage.
[0051]
Thus, a substrate as shown in FIG. 4 is obtained. In this type of liquid crystal display device, when viewed obliquely from the direction of the arrow D, a strong viewing angle dependency appears in the region a, and the display becomes invisible. That is, the region a looks black or black regardless of the display signal. On the other hand, when viewed from the direction opposite to the arrow D, the region b is not visible.
[0052]
This will be further described with reference to FIG. FIG. 5 is an enlarged view of the surface portion of the liquid crystal display device as seen from the cross-sectional direction. FIG. 5A shows the state on the region a, and FIG. 5B shows the state on the region b. Actually, the regions a and b are defined on the alignment film, but here, the corresponding regions of the regions a and b are conceptually shown.
[0053]
FIG. 5A shows an image visible area 51 and an image invisible area 52 on the area a. That is, when the screen is viewed from the image visible region 51, it functions as a normal liquid crystal display device according to the state of the liquid crystal. On the other hand, when the screen is viewed from the image invisible region 52, it always looks black or black regardless of the state of the liquid crystal. Hereinafter, a black or blackish display is expressed as “black”. For example, when viewed from the direction D, the region a looks black.
[0054]
FIG. 5B shows an image visible area 53 and an image invisible area 54 on the area b. In the area b, the image displayed by the liquid crystal in the area b can be seen from the direction D. However, the region b looks black from the image invisible region 54.
[0055]
Since the region a and the region b are arranged next to each other, when viewed from a certain direction, for example, the direction D, the normal liquid crystal display can be seen for the region b, but the region a looks black and is displayed on the liquid crystal display device. I cannot see the entire image.
[0056]
Accordingly, it is difficult to understand the screen display information because it is not possible to see all of the display except when viewed almost from the front. That is, from the direction other than the front, a black square of the area a or b is visually recognized on the display screen, and the display screen is scrambled.
[0057]
For example, consider a case where a figure as shown in FIG. 6 is displayed on a liquid crystal display device. At this time, the display device can be correctly viewed from almost the front as shown in FIG. However, when viewed from an oblique lateral direction, for example, from the direction D, the image appears black as shown in FIG. 7, and the displayed content cannot be viewed accurately or is difficult.
[0058]
Kanji characters, hiragana, alphabets, and photographs were displayed on the liquid crystal display device of this embodiment, and images were shown to 15 subjects from each direction from 1 to 8 in FIG. At this time, an angle at which the displayed image could be read was measured, and an average value was calculated for a plurality of measurements. Here, the angle at which an image can be read is the normal direction of the screen, that is, the front is 0 degrees, and the deviation from this is displayed as an angle. Moreover, the display image measured about the figure and the character.
[0059]
The result of this measurement is shown in FIG. The measurement results for the first embodiment are listed in the first column in FIG.
[0060]
With respect to the figure, in the directions 1 and 5, that is, in the left-right direction, the display figure cannot be read if it is deviated about 16 degrees from the front. Further, in directions 3 and 7, that is, in the vertical direction, reading was possible up to about 32 degrees from the front. In directions 2, 4, 6, and 8, which are intermediate between the left and right directions and the up and down directions, reading was possible up to about 18 degrees from the front.
[0061]
In addition, it is difficult to read the characters in the left-right direction if they are deviated from the front by about 15 degrees. The vertical direction could be read up to about 30 degrees.
[0062]
The area that can be read is slightly narrower for characters, but this is generally expected because characters are finer and more complex, but there is not much difference between graphics and characters.
[0063]
As can be seen from this measurement result, the liquid crystal display device provided with the regions a and b as in the present embodiment can see a normal image from the front, but from the front from the left and right lateral oblique directions. If the angle deviates more than 20 degrees, a normal image cannot be seen. As a result, it is not possible to accurately grasp the displayed image from the lateral direction, and it is possible to realize an apparatus in which only the user of the liquid crystal display device can view the image.
[0064]
For example, it is possible to realize a device in which only a user can see a screen of a mobile terminal or a mobile phone operated on the palm of the hand, but a surrounding person cannot look into. When the display screen is viewed from a direction other than the front direction, the orientation film pattern is visually recognized regardless of the display image depending on the direction. Therefore, it is preferable to select an appropriate pattern according to the purpose of the image to be displayed.
[0065]
In this embodiment, a so-called normally black type liquid crystal display device in which pixels display black when no voltage is applied has been described, but conversely, a so-called no display where pixels display white when no voltage is applied. It is also possible to use a Marie white liquid crystal display device. In the case of the normally white method, it is preferable to apply 0.5% to 70% of the saturation voltage as a bias voltage to the pixel, and more preferably 5% to 20%, so that the same as in the normally black method. The effect is obtained.
(Second Embodiment)
Next, a second embodiment will be described.
[0066]
In the second embodiment, the pattern of the region a and the region b is as shown in FIG. Other configurations are the same as those in the first embodiment. In the present embodiment, the vertical direction of the image observer and the diagonal lines of the areas a and b are made to coincide. However, as an embodiment, a pattern as shown in FIG. 10 will be described, but it is also possible that the vertical direction does not coincide with the diagonal direction of the regions a and b.
[0067]
Also in this embodiment, the rubbing direction of the upper substrate in the regions a and b is represented by a dotted arrow, and the rubbing direction of the lower substrate is represented by a solid arrow. In the pattern of this example, the square area is a pattern rotated by 45 degrees from the first embodiment. The regions a and b are squares with sides of about 2.5 mm.
[0068]
In the liquid crystal display device of this embodiment, the viewing angle is evaluated in the same manner as in the first embodiment, and the average value of the angles formed with the screen vertical direction is shown in FIG. Also in this embodiment, the angle at which a display image can be read was measured for graphics and characters.
[0069]
Also in this example, almost the same measurement result as in the first example was obtained, and the readable angle could be reduced in the left-right direction.
(Third embodiment)
Next, a third embodiment will be described.
[0070]
In the third embodiment, STN material ZLI-4540 (270-degree twist) manufactured by Merck Japan Ltd. is used as the liquid crystal material. Further, striped ITO electrodes are provided on the upper and lower glass substrates. However, the striped ITO electrodes are arranged so that the ITO electrode on the upper substrate and the ITO electrode on the lower substrate are orthogonal when the upper and lower glass substrates are opposed to each other. The other materials and conditions are the same as those in the second embodiment.
[0071]
The striped ITO electrodes are about 200 μm wide and the distance between the electrodes is about 20 μm.
[0072]
An alignment film is formed on the ITO electrodes provided on the upper and lower substrates, and a rubbing process similar to that of the second embodiment is performed. As a result, regions a and b are formed on the substrate.
[0073]
Here, a polarizing plate is provided so as to be black when no voltage is applied. The maximum voltage used during driving is approximately 70% of the saturation voltage of the liquid crystal.
[0074]
When a predetermined potential is applied to the selected ITO electrodes on the upper and lower substrates, the liquid crystal at the intersection of the ITO electrodes changes the molecular direction under the influence of the electric field, and the light transmittance changes, resulting in a desired image. Can be displayed.
[0075]
Also in this embodiment, since the regions a and b are provided, a normal image can be seen from the front, but only one of the region a or the region b can be seen from the oblique lateral direction. Therefore, the entire image cannot be viewed.
[0076]
In the liquid crystal display device of this embodiment, the viewing angle was evaluated in the same manner as in the first embodiment. The result is shown in FIG.
[0077]
Also in this embodiment, it can be seen that the reading angle of the display image is limited in the left-right direction. In this embodiment, the viewing angle is originally small and the image cannot be read if it is deviated by about 25 degrees from the front. In particular, in directions 1 and 5, the display image can be read if it is deviated from 11 to 14 degrees from the front. Disappear. That is, by providing the regions a and b, the viewing angle in the left-right direction could be limited.
[0078]
Also in this embodiment, in the case where the arrangement of the polarizing plate is made white with no voltage applied, applying a bias voltage to the entire surface is effective for narrowing the viewing angle. Here, the bias voltage to be applied is 0.5% to 70%, more preferably 5% to 2%, of the saturation voltage of the liquid crystal.
(Fourth embodiment)
Next, a fourth embodiment will be described.
[0079]
The fourth embodiment uses a twisted FLC type ferroelectric liquid crystal 2005 manufactured by Chisso Petrochemical Co., Ltd., which exhibits high-speed response as the liquid crystal material. Further, the thickness of the liquid crystal material layer, that is, the cell gap is about 2 μm, and the maximum drive voltage is the saturation voltage of the liquid crystal layer. The optical axis direction of the polarizing plate was made parallel to the rubbing direction on each substrate. In this case, a white display state is obtained when no voltage is applied, and the viewing angle of each region is maximized when no voltage is applied. The rest is the same as in the first embodiment.
[0080]
In the liquid crystal display device of this embodiment, the viewing angle is evaluated in the same manner as in the first embodiment, and the average value of the angles formed with the screen vertical direction is shown in FIG.
[0081]
In the case of the present embodiment, in the up-down direction, that is, the direction 3 and the direction 7, it is possible to see the display image even if it is deviated by 50 degrees from the front. If it deviates about 15 degrees from the front, the image cannot be read. In this embodiment, the effect of providing the regions a and b is remarkable.
[0082]
Next, a comparative example is shown.
[0083]
(Comparative Examples 1, 2, 3)
The orientation was processed as shown in FIG. 11 without dividing the orientation direction into a plurality of regions. Other than this, a liquid crystal display device was formed by the same method as in the second, third, and fourth embodiments, and Comparative Examples 1, 2, and 3 were used, respectively. Also in each of these comparative examples, the rubbing direction of the upper substrate is represented by a dotted arrow, and the rubbing direction of the lower substrate is represented by a solid arrow.
[0084]
Also in the liquid crystal display devices of these comparative examples, the viewing angle is evaluated in the same manner as in the first embodiment, and the average value of the angles formed with the screen vertical direction is shown in FIG.
[0085]
In Comparative Example 1, when viewed from the direction 1, the image can be viewed up to about 40 degrees from the front, but from the opposite direction 5, the image cannot be viewed if the position is shifted from the front by about 15 degrees. In addition, if the image is deviated from the front by about 30 degrees in the vertical direction, the image cannot be viewed. Also in this case, the normal image can be seen from the front, but the display image can be seen in a wide range from the direction 1.
[0086]
In Comparative Example 2, the image cannot be seen from direction 1 when it is shifted 23 or 24 degrees from the front, and from direction 5, the image cannot be viewed when it is shifted about 10 degrees from the front. From the vertical direction, the image cannot be viewed if it is shifted by about 20 degrees. Also in this case, the display image can be viewed in a wide range from the direction 1.
[0087]
In Comparative Example 3, the image can be viewed from the direction 1 up to about 70 degrees from the front, but from the direction 5, the image cannot be viewed if it is displaced 20 degrees from the front. Accordingly, the display image can be seen in a wide range from the direction 1.
[0088]
Referring to FIG. 9, the TN method is compared between the first and second embodiments and Comparative Example 1, the STN method is compared between the third embodiment and Comparative Example 2, and the fourth embodiment and Comparative Example 3 are compared. Compare torsional FLC methods.
[0089]
In any of these methods, it can be seen that each embodiment of the present invention dramatically narrows the viewing angle in the left-right direction. Therefore, it can be seen that the narrow viewing angle of the present invention can be used in any of these liquid crystal materials. In particular, since the twisted FLC system exhibits high-speed response, when the display quality was confirmed from the front, a clear moving image could be confirmed.
[0090]
In the above-described embodiment, since the orientation process is performed so as to limit the viewing angle in the left-right direction, a result as shown in FIG. 9 can be obtained. It goes without saying that the viewing angle in an arbitrary direction can be limited by changing the orientation direction.
[0091]
(Comparative Example 4)
A liquid crystal display device similar to that of the first embodiment is used, and a saturation voltage of the liquid crystal layer is applied to obtain a comparative example 4. The viewing angle is evaluated in the same manner as in the first embodiment, and the average value of the angles formed with the screen vertical direction is shown in FIG.
[0092]
In Comparative Example 4, the display image disappears from the horizontal direction, that is, from the direction 1 and the direction 5 when it deviates about 25 degrees from the front, but in the vertical direction, the display image can be viewed up to 30 degrees from the front. And there was little change depending on the viewing direction.
[0093]
When comparing the first embodiment and Comparative Example 4, it was confirmed that the viewing angle was widened when the maximum drive voltage was the saturation voltage of the liquid crystal layer. Therefore, in a liquid crystal display element that displays black when no voltage is applied, the maximum drive voltage is preferably about 90% or less of the saturation voltage of the liquid crystal layer. This is because the TN and STN liquid crystals do not have a large viewing angle dependency when no voltage is applied or when a saturation voltage is applied. .
[0094]
On the other hand, a maximum drive voltage corresponding to about 40% or more of the saturation voltage of the liquid crystal layer is required. This is because if it is about 40% or less, the desired contrast cannot be obtained and the image quality deteriorates.
[0095]
For a liquid crystal element that displays white when no voltage is applied, it is effective to apply a bias voltage of 0.5% to 70%, preferably about 5% to 20% of the saturation voltage of the liquid crystal to all pixels. . This is because, in the TN and STN systems, the viewing angle is remarkably narrowed when a bias of about 5% to 20% is applied compared to a complete white display state.
(Fifth embodiment)
Next, a fifth embodiment will be described.
[0096]
In this example, the same liquid crystal display device as that in the first embodiment is used. However, the liquid crystal display device described in the second and subsequent embodiments can also be used, and a liquid crystal display device having the same function can be used. It is also possible.
[0097]
When the display screen is viewed from a direction other than the front direction, the alignment film pattern is visually recognized regardless of the display signal depending on the viewing direction, so that a desired fixed pattern can be seen when viewed from the lateral direction.
[0098]
That is, by utilizing the fact that a fixed pattern unrelated to the display signal is visually recognized from a direction other than the front direction, a specific figure can be displayed from a direction other than the front. For example, in the first embodiment, the checkered pattern as shown in FIG. 7 is illustrated, but if the areas a and b are arranged in an appropriate pattern, an arbitrary figure can be displayed as a fixed pattern. That is, it is possible to form a desired alignment pattern on the alignment film.
[0099]
As this fixed pattern, for example, it is possible to form a pattern so that a product name or a company name logo can always be seen when viewed from the side, or to make an animation character visible from the side. Thus, it is effective when a liquid crystal display device capable of displaying a fixed pattern such as a product name is incorporated in a mobile phone and the mobile phone is presented to a consumer as a prize.
[0100]
For example, when the display of FIG. 6 is performed, when viewed from the side, the image displayed by the liquid crystal layer and the region with a different orientation direction can be seen to overlap each other as shown in FIG. . In this way, company names, product names, and fixed figures can be displayed as fixed patterns. Here, the fixed pattern such as the company name is independent of the display image of the liquid crystal layer and independent of the input signal to the liquid crystal layer.
[0101]
FIG. 13 shows an example in which a heart shape is used as a region where the orientation directions are different. When such a single figure that occupies a large part of the screen is used and the alignment film is divided into two types of regions a and b, for example, if it looks as shown in FIG. From the left side, the figure displayed on the liquid crystal layer is visible inside the heart shape, and the outside of the heart shape appears black. In this example, a heart shape is illustrated, but an arbitrary pattern can be formed as a fixed pattern.
[0102]
When a large single pattern is used for the screen, the fixed pattern works effectively as a message, but the effect of making it difficult to look into the display contents from the side is diminished. On the other hand, using a fine pattern is effective in preventing peeping, but it reduces the ability to transmit messages. However, the effects of peeping prevention and message transmission coexist. Since the fixed pattern can be designed arbitrarily, the fixed pattern can be created in consideration of the balance of this effect.
[0103]
Since the fixed pattern only needs to be designed in a region where the orientation direction is changed, a large change is not necessary in the manufacturing process of a normal liquid crystal display device. In addition, a pattern for forming regions having different orientation directions can be easily formed, and there is no significant time loss as compared with a normal manufacturing process.
(Sixth embodiment)
Next, a sixth embodiment will be described.
[0104]
Also in this embodiment, the liquid crystal display device used in the first embodiment can be used. However, the present invention can be applied to the liquid crystal display device described below in the second embodiment and other liquid crystal display devices capable of color display. It is.
[0105]
As an example of a liquid crystal display device for color display, pixels for displaying red (R), green (G), and blue (B) are arranged as shown in FIG. The arrangement of RGB is not necessarily limited to that shown in FIG.
[0106]
Here, as in the first embodiment, the alignment film is partitioned into a region a and a region b. The partition area includes a plurality of pixels and must be partitioned so that it can be seen with eyes. For example, if the regions a and b are partitioned as shown in FIG. 2, the regions a and b each have a size including a plurality of pixels. Therefore, it should be noted that the region a includes a plurality of RGB pixels as shown in FIG. The same applies to the region b.
[0107]
Hereinafter, the description will be given focusing on the region a, but the same applies to the region b.
[0108]
For example, only the alignment direction of the pixel R in the region a is different from the alignment direction of the pixel G and the pixel B. For example, as shown in FIG. 15, the alignment direction may be such that the rubbing direction of the pixel R and the rubbing directions of the pixel G and the pixel B are reversed.
[0109]
With this configuration, for example, when viewing the screen from the direction D, the portion of the region a can be seen as blue-green, and when seen from the opposite lateral direction, the portion of the region a can be seen as red. That is, by selectively changing the orientation direction of only a specific color pixel in the region a, the color can be seen when viewed from the lateral direction.
[0110]
As described above, if the region a can be colored, similarly to the fifth embodiment, if a desired pattern is formed, a colored fixed image is shown when viewed from the side. Can do it.
[0111]
The desired color can be expressed by the method of selecting the pixel RGB in the region a. For example, when regions having different orientation directions are formed in units of pixels, eight colors can be displayed when a specific fixed pattern is viewed from one direction. However, it is possible to divide one pixel at an arbitrary ratio without using regions with different orientation directions as pixel units. By doing so, it is possible to display a fixed pattern showing an arbitrary gradation and an arbitrary color tone. Therefore, it is possible to display a fixed pattern such as a photograph.
[0112]
According to this embodiment, it is possible to color a desired fixed pattern.
[0113]
In the above embodiment, the example which uses the mask rubbing method which physically shields other than a rubbing area | region was demonstrated as a method of forming the area | regions a and b. In addition to this, as a method of forming a plurality of regions having different alignment directions, a method of forming a portion having different viewing angle dependency by irradiating light to a part of the alignment film after rubbing to change the pretilt angle. There is.
[0114]
A method of changing the pretilt angle by irradiating this light will be described with reference to FIGS.
[0115]
First, a polyimide film is formed on the glass substrate 121, and, as shown in FIG. 16, the entire surface is rubbed so as to have a predetermined orientation direction (for example, an arrow direction).
[0116]
On the other hand, a photomask 131 having a pattern as shown in FIG. 17 is prepared.
[0117]
Through this photomask 131, the glass substrate 121 is irradiated with visible ultraviolet light from a high pressure mercury lamp of about 10 J / cm 2. By this ultraviolet irradiation, the pretilt angle decreases in the region irradiated with the ultraviolet rays.
[0118]
Next, a polyimide film is similarly formed on the substrate facing the glass substrate 121, and a rubbing process is performed. The opposite substrate is irradiated with ultraviolet rays in the same manner through a photomask having a reverse pattern in which the opening of the photomask 131 in FIG. 17 is shielded and the shield is opened. These two substrates are arranged so that the ultraviolet irradiation part and the non-irradiation part face each other.
[0119]
A nematic liquid crystal material is injected between the substrates formed as described above to produce a liquid crystal display device.
[0120]
Here, in the region where only the rubbing process is performed, when the right-twisted structure is stable, the left-twisted liquid crystal is used. Conversely, in a region where only the rubbing process is performed, when the left-twisted structure is stable, right-twisted liquid crystal is injected. Then, it is possible to form two regions having different viewing angle-dependent directions.
[0121]
For example, when forming a region having a plurality of orientation directions, the orientation direction may be two or more. If there are two types of orientation directions, it will be difficult to recognize from directions other than the intended direction.
[0122]
In the above-described embodiment, for example, an example has been described in which a region that appears black when viewed from direction 1 in FIG. 8 and a region that appears black when viewed from direction 5 are complementarily arranged. There is no need to be correct. That is, an area that appears black when viewed from direction 1, an area that appears black when viewed from direction 5, and an area where a normal image can be viewed from both directions 1 and 5 can be arranged on the screen.
[0123]
In addition, the shape, size, and the like of regions having different orientation directions can be selected as appropriate from the application, design, and the like. For example, the region is arbitrary, such as a parallelogram, a polygon such as a triangle, a circle, an ellipse, or the like. The size of the area can also be changed depending on the application.
[0124]
For example, in order to make it difficult to visually recognize the image displayed by the liquid crystal layer from a direction other than the front, it is preferable to arrange a small pattern, and consider a minimum rectangle (including a square) containing the region, When the long side of this rectangle is about 0.1 mm or more and about 1 cm or less, it becomes difficult to visually recognize from directions other than the front. Furthermore, the long side of the rectangle is preferably about 0.5 mm or more and about 5 mm or less.
[0125]
In addition, there are two methods of placing the polarizing plate of the liquid crystal display device: a method of arranging so as to display black when no voltage is applied, and a method of arranging so as to display white.
[0126]
According to the narrow viewing angle in the present invention, it is preferable to drive the liquid crystal layer at a saturation voltage or lower, so it is better to set black display when no voltage is applied. Then, sufficient black display can be performed, and a liquid crystal display device with good image quality is obtained. However, even in a liquid crystal display element that performs white display when no voltage is applied, a bias voltage of 0.5% to 70%, preferably 5% to 20% of the saturation voltage of the liquid crystal is applied to all pixels when performing white display. Thus, the same effect can be obtained.
[0127]
In the above embodiment, an example in which liquid crystal is sandwiched between flat substrates has been described. However, in a single substrate type liquid crystal display device in which an alignment film, a liquid crystal layer, an alignment film, and a protective film are stacked on a lower substrate. It is possible even if it exists.
[0128]
Furthermore, the liquid crystal display device of the present invention can have two liquid crystal layers. Here, the liquid crystal layer far from the user is called a lower liquid crystal layer, and the near liquid crystal layer is called an upper liquid crystal layer. This lower liquid crystal layer is a layer for normal display. Further, the upper liquid crystal layer has a plurality of regions having different alignment directions, and is arranged so that the alignment directions of adjacent regions are different. Then, the upper liquid crystal layer is a layer that displays a predetermined figure when viewed from other than the front.
[0129]
If the upper liquid crystal layer is in the intermediate display state, the image displayed on the lower liquid crystal layer can be seen from the front, but when viewed from a direction other than the front, the upper liquid crystal layer is blocked by the figure of the upper liquid crystal layer, It becomes difficult to see the image of the lower liquid crystal layer.
[0130]
In addition, by applying an electric field to the upper liquid crystal layer and causing the liquid crystal molecules in the upper liquid crystal layer to stand, the display becomes uniform and the display of the lower liquid crystal layer can be seen even when viewed from a direction other than the front. . That is, it is possible to perform switching so that the display of the lower liquid crystal layer can be seen or not seen from a direction other than the front.
[0131]
The above-described liquid crystal display device can be incorporated in a mobile phone, a mobile terminal, a laptop computer, or the like. For example, when a liquid crystal screen 1902 is provided in a mobile phone 1901 as shown in FIG. 18, the liquid crystal display device of the above embodiment can be incorporated in the liquid crystal screen 1902. In addition, the mobile terminal 2001 as shown in FIG. 19 can also be incorporated when the liquid crystal screen 2002 is provided.
[0132]
By applying to such a terminal, it is possible to prevent a peep from the horizontal direction or to display a product logo or the like in the horizontal direction.
[0133]
【The invention's effect】
As described above in detail, according to the liquid crystal display device of the present invention, since a fixed pattern unrelated to the display screen can be seen from a direction other than the front of the liquid crystal display device, the display content can be recognized from other than the front direction. Can be difficult. Therefore, it is possible to prevent the display content from being seen by others by so-called peeping. Moreover, it is possible to display a figure, a brand name, etc. on this fixed pattern.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a liquid crystal display device according to a first embodiment of the present invention.
FIG. 2 is a plan view for explaining the distribution of regions a and b having different liquid crystal alignment directions in the liquid crystal display device according to the first embodiment of the present invention.
FIG. 3 is a diagram for explaining alignment directions of a region a and a region b. Here, the solid line arrow indicates the rubbing direction of the lower substrate, and the dotted line arrow indicates the rubbing direction of the upper substrate.
FIG. 4 is a diagram illustrating an alignment direction of a liquid crystal display device. Here, direction D indicates a case where the liquid crystal display device is viewed from the left lateral direction from the front.
FIG. 5A is a conceptual diagram showing a direction (visible region) 51 in which an image displayed on a liquid crystal can be seen and a direction (invisible region) 52 in which an image cannot be seen in the region a. . FIG. 5B is a conceptual diagram showing the visible region 53 and the invisible region 54 of the image displayed on the liquid crystal for the region b. When the liquid crystal is viewed from the invisible regions 52 and 54, it looks black.
FIG. 6 is an example when a diagram is displayed on the liquid crystal display device of the first embodiment and viewed from the front.
7 is a liquid crystal display device when the liquid crystal display device displaying the image of FIG. 6 is viewed from the direction D of FIG. When viewed obliquely from the side, either the region a or the region b looks black and the displayed image is difficult to see.
FIG. 8 is a diagram illustrating a direction used when measuring that the viewing angle differs depending on the viewing direction. In the measurement, the viewing angle was measured from 8 directions from 1 to 8.
FIG. 9 is a result of measuring the viewing angle dependency of the liquid crystal display devices of the first to fourth embodiments.
FIG. 10A is a plan view for explaining regions having different alignment directions of liquid crystal in a liquid crystal display device according to a second embodiment of the present invention. FIG. 10B is a diagram showing the rubbing direction in the region a and the region b in FIG.
FIG. 11 is a plan view illustrating a rubbing direction of liquid crystal of a liquid crystal display device of a comparative example.
12 is a diagram for explaining that a logo such as a company name and a product name is superimposed on the display illustrated in FIG. 6 when viewed from the side.
FIG. 13 is a diagram for explaining that graphics are displayed so as to overlap the display illustrated in FIG. 6 when viewed from the side;
FIG. 14 is a diagram for explaining that red, green, and blue pixels of a color liquid crystal display device are arranged in a region a.
FIG. 15 is a diagram for explaining changing the orientation direction of the pixel R, the pixel G, and the pixel B;
FIG. 16 is a diagram illustrating a state where uniform rubbing is performed on an alignment film on a substrate.
FIG. 17 is a diagram showing an example of a photomask used when the state of the alignment film is changed by light.
FIG. 18 is an example in which the liquid crystal display device according to the present embodiment is applied to a mobile phone.
FIG. 19 is an example in which the liquid crystal display device according to the present embodiment is applied to a mobile terminal.

Claims (15)

A liquid crystal layer, an alignment film sandwiching the liquid crystal layer, and a driving means for driving the liquid crystal layer,
The alignment film includes a liquid crystal display device that is partitioned into viewing regions containing a plurality of pixels in units of pixels, the alignment directions are the same in the regions, and the alignment directions of the adjacent regions are different. A terminal device. A liquid crystal layer, an alignment film sandwiching the liquid crystal layer, and a driving means for driving the liquid crystal layer,
The alignment film is partitioned into viewing regions containing a plurality of pixels in units of pixels, the alignment direction of pixels of the same color is the same in one region, and at least one color pixel is adjacent between the regions A terminal device comprising a liquid crystal display device having a different orientation direction from that of an adjacent region. A liquid crystal layer, an alignment film sandwiching the liquid crystal layer, and a driving means for driving the liquid crystal layer,
The alignment film is partitioned into a plurality of viewing regions having different alignment directions, the alignment direction is the same in the region, and the area ratio of the region in at least one pixel is the area of the region in another pixel A terminal device comprising a liquid crystal display device having a different ratio. The terminal device according to claim 1, wherein the area is a character. The terminal device according to claim 1, wherein the area forms a visual figure. A first liquid crystal layer that performs image display based on an input signal, a second liquid crystal layer, and an alignment film that sandwiches the second liquid crystal layer, and the alignment film is partitioned into a plurality of regions having different alignment directions; A terminal device comprising a liquid crystal display device that forms a fixed image in which the region is visible. The terminal device according to claim 6 , further comprising applying means for applying an electric field to the second liquid crystal layer. The terminal device according to claim 7, wherein display or non-display of the fixed image is switched. The terminal device according to claim 6 , wherein the fixed image is a character. The terminal device according to claim 6, wherein the fixed image is a visual figure. A liquid crystal layer, an alignment film sandwiching the liquid crystal layer, and a driving means for driving the liquid crystal layer,
The alignment film includes a liquid crystal display device that is partitioned into viewing regions containing a plurality of pixels in units of pixels, the alignment directions are the same in the regions, and the alignment directions of the adjacent regions are different. A portable terminal device. A liquid crystal layer, an alignment film sandwiching the liquid crystal layer, and a driving means for driving the liquid crystal layer,
The alignment film is partitioned into viewing regions containing a plurality of pixels in units of pixels, the alignment direction of pixels of the same color is the same in one region, and at least one color pixel is adjacent between the regions A portable terminal device comprising a liquid crystal display device having a different orientation direction from that of an adjacent region. A liquid crystal layer, an alignment film sandwiching the liquid crystal layer, and a driving means for driving the liquid crystal layer,
The alignment film is partitioned into a plurality of viewing regions having different alignment directions, the alignment direction is the same in the region, and the area ratio of the region in at least one pixel is the area of the region in another pixel A portable terminal device comprising a liquid crystal display device having a different ratio. Mobile terminal device according to any one of claims 1 1 to claim 1 3 wherein the region is characterized by forming the character. Mobile terminal device according to any one of claims 1 1 to claim 1 3 wherein the region is characterized by forming a visual graphic.

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