JP2006350323A - Liquid crystal display device and manufacturing method of liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which has high durability and is capable of displaying high-quality image, and to provide manufacturing equipment of the liquid crystal display device. <P>SOLUTION: An inorganic alignment film is used as an alignment film of a liquid crystal display element 120, and light L1 from a light source 50 is bent at a right angle by a semi-transmission plate 55, thereafter, is converted into an elliptically polarized light or a circularly polarized light and is made incident to the liquid crystal display element 120 by a circularly polarizing means 53. Thereafter, the elliptically polarized or circularly polarized light L1 is reflected by the liquid crystal display element 120 and is selectively transmitted by the semi-transmission plate 55. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device and a method for manufacturing the liquid crystal display device, and more particularly to a liquid crystal display device using an inorganic alignment film as an alignment film.

  At present, liquid crystal display devices are widely put into practical use, and it is considered that their use will be further promoted in the future. Such a liquid crystal display device can be classified into a direct-view type in which the liquid crystal element is observed as it is and a projection type in which an image larger than the size of the liquid crystal element can be observed using an enlargement optical system. .

  Since the projection type liquid crystal display device can easily realize a large screen display, it is widely used as a front projector that projects from the front of the screen and a rear projector that projects from the back of the screen. Here, in this projection type liquid crystal display device, an optical shutter which is a display element using liquid crystal for modulating light from a light source and projecting it on a screen plays a central role.

  As the optical shutter, a so-called LCOS (Liquid Crystal On Silicon) device is mainly used. This LCOS has a structure in which an electrode and an alignment film are formed on a semiconductor chip on which a drive circuit is built, a transparent glass substrate is placed opposite the chip surface, and a liquid crystal is arranged in the gap. is there. A transmissive liquid crystal device using transparent glass substrates facing each other is also used.

  By the way, in the projection type liquid crystal display device, in order to obtain sufficient brightness on the screen, the liquid crystal shutter is irradiated with extremely strong light. However, when the conventional liquid crystal shutter is irradiated with such strong light, there is a problem that the alignment film made of the organic polymer material is deteriorated and the life is shortened.

  Therefore, as a method for solving this problem, it has been proposed to use an alignment film made of an inorganic material instead of an organic polymer alignment film such as polyimide, which has been widely used, as an alignment film (see Patent Document 1). ). In general, since the organic alignment film is inferior in light resistance, the use of the inorganic alignment film instead of the organic alignment film in this way can suppress deterioration in display quality due to irradiation with strong light.

  A typical method for forming a liquid crystal alignment film using an inorganic material is oblique deposition of silicon oxide (hereinafter referred to as SiOx). In this oblique vapor deposition method, SiOx as a vapor deposition source is placed in a vacuum atmosphere and heated to a high temperature or irradiated with an electron beam to evaporate SiOx molecules and deposit them on a vapor deposition substrate from an oblique direction. The SiOx deposited on the substrate in this way is a fine inclined columnar structure (hereinafter referred to as a column). Liquid crystal molecules are believed to be aligned along this column.

  Hereinafter, the direction in which the vapor deposition beam comes at each position of the substrate is referred to as a vapor deposition direction, and the angle formed by the vapor deposition beam and the substrate normal is referred to as a vapor deposition angle. That is, the vapor deposition angle is an incident angle of the vapor deposition beam on the substrate in the vapor deposition direction.

  According to the experience of the present inventors, the column growth direction and the vapor deposition direction are almost the same. On the other hand, the deposition angle is not the same as the angle of the formed column with respect to the substrate, but there is a certain correlation. The deposition angle is the most important factor for controlling the pretilt angle of the liquid crystal.

  By the way, the problem of this oblique vapor deposition method is that the vapor deposition method is vapor deposition from a point-shaped vapor deposition source, so that the vapor deposition direction and vapor deposition angle are different at each point on the substrate to be deposited. It is not constant in the plane, and the column is formed at different orientations and angles at each location on the substrate.

  Therefore, in order to improve such variation in the column growth direction, a method of aligning the vapor deposition angle with a mask provided with a slit has been proposed (see Patent Document 2). In this case, it is disclosed that the deposition angle is determined by the relative arrangement of the deposition source and the slit, and a substantially constant deposition angle is obtained.

  However, even in this method, since the direction of the vapor deposition beam from the vapor deposition source has an angular distribution over the length of the slit, the vapor deposition angle and the vapor deposition orientation are not completely uniform on the substrate. And when the vapor deposition angle is different, the pretilt angle of the liquid crystal is different. Moreover, the variation in the vapor deposition direction causes the variation in the alignment direction of the liquid crystal. Hereinafter, how these liquid crystal alignments affect the optical characteristics will be described.

  FIG. 15 is a calculation result showing how much the reflectance of the reflective liquid crystal shutter varies depending on the pretilt angle of the liquid crystal. In this case, it is assumed that the liquid crystal is a so-called vertical alignment (VA) mode liquid crystal that is aligned vertically with respect to the substrate when no voltage is applied and tilts with the voltage. In the case of this liquid crystal, light is not transmitted when the voltage is 0 V, and the liquid crystal is inclined and light is transmitted as the voltage is increased.

  The pretilt angle of the liquid crystal is determined by the vapor deposition angle during oblique vapor deposition, but as described above, the vapor deposition angle varies in oblique vapor deposition, so the pretilt angle also differs depending on where the chip was cut from the wafer. Yes. Note that the three curves in FIG. 15 show the reflectance when the pretilt angles are 90 degrees, 88 degrees, and 86 degrees, respectively. From FIG. 15, it can be seen that the reflectivity changes considerably due to the fluctuation of several degrees of the pretilt angle.

  FIG. 16 shows the reflectance when the orientation in which the liquid crystal molecules tilt when the voltage is applied is changed in the same VA mode liquid crystal. The tilt direction of the liquid crystal is the tilt direction of the SiOx column determined by the deposition direction of oblique deposition. As described above, since the deposition direction varies in oblique deposition, the tilt direction of the column also differs depending on from which position of the wafer the chip is cut.

  FIG. 16 shows how the reflectance changes when the tilt direction of the liquid crystal molecules is 45 degrees, 40 degrees, and 35 degrees with respect to the polarization axis. Then, as shown in FIG. 16, the vapor deposition azimuth varies depending on the chip, so that the tilt azimuth of the liquid crystal varies, and the maximum reflectance decreases as it deviates from 45 degrees.

  As described above, the reflectance variation of the reflective liquid crystal display element has been described as an example, but the same transmittance change occurs in the transmissive liquid crystal element using the VA mode.

JP 08-136932 A JP-A-63-172121

  By the way, since the semiconductor chip on which the liquid crystal shutter is formed has a size of several millimeters to several centimeters, the liquid crystal alignment characteristics of the liquid crystal and the optical characteristics determined thereby may be considered uniform within the chip.

  However, when vapor deposition is performed on several inch silicon wafers, the column directions are quite different at both ends of the wafer. When this wafer is scribed into chips, there are non-negligible variations between chips. In particular, if the orientation direction of the liquid crystal in the substrate surface varies depending on the chip, the optical axis as a liquid crystal shutter is not constant, and when mounted on the projector, the optical axis is displaced with respect to the direction of the optical axis fixed to the projector. This fatally deteriorates the contrast of the displayed image.

  Here, in many conventional projection-type liquid crystal display devices, three liquid crystal shutters are used corresponding to the three primary colors. If the characteristics of each shutter vary in this way, the color displayed for each product changes and becomes uniform. Color reproduction cannot be obtained. Also, the display quality of individual products is not improved.

  Furthermore, in the conventional method for manufacturing a liquid crystal display device, only chips cut out from a very small part of the wafer can be used in order to suppress the variation of the liquid crystal shutter within a narrow range. For this reason, it is difficult to reduce the cost per chip.

  Therefore, the present invention has been made in view of such a situation, and an object thereof is to provide a liquid crystal display device capable of displaying a high-durability and high-quality image and a liquid crystal display device manufacturing apparatus. To do.

  The present invention provides a liquid crystal element comprising a pair of substrates, an alignment film made of an inclined columnar structure of an inorganic material, provided on at least one of the pair of substrates, and a liquid crystal disposed between the pair of substrates. A liquid crystal display device that has a light source and modulates and emits light from the light source, and includes circularly polarizing means that converts the light from the light source into circularly polarized light or elliptically polarized light and enters the liquid crystal element. It is characterized by.

  As in the present invention, the inorganic alignment film is used to increase durability, and the incident light from the light source is converted into circularly polarized light or elliptically polarized light to irradiate the liquid crystal element. An image can be displayed.

  Next, an embodiment of the present invention will be described using a reflective liquid crystal element.

  FIG. 1 is a diagram illustrating a configuration of a liquid crystal shutter which is an example of a liquid crystal device (liquid crystal display element) provided in a liquid crystal display device such as a projector. In FIG. 1, 120 is a liquid crystal shutter. The liquid crystal shutter 120 includes a glass substrate 121, a silicon substrate 127, electrodes 122 and 126 formed on the substrates 121 and 127, alignment films 123 and 125 formed on the electrode surfaces, and substrates 121 and 127. A liquid crystal layer 124 sandwiched between the two. Note that light enters from above in FIG. 1, is reflected by the metal electrode 126 provided on the substrate 127 opposite to the observer side made of metal such as aluminum, and is emitted upward again.

  Here, the alignment films 123 and 125 of the liquid crystal shutter 120 are formed on the substrate by a vapor deposition apparatus provided in a liquid crystal display manufacturing apparatus employing the oblique vapor deposition method shown in FIG. In FIG. 2, reference numeral 5 denotes a vapor deposition source, 1 denotes a substrate, and the substrate 1 is disposed so as to be movable at an angle θ with respect to the vapor deposition beam. The vapor deposition source 5 is a point source, and the vapor deposition beam is incident on the substrate 1 through the slit 4. It is assumed that the slit 4 is provided perpendicular to the moving direction of the substrate 1. The vapor deposition apparatus shown in FIG. 2 will be described later.

As the deposition material, SiO is often used. When a substrate on which SiO is deposited is observed with an electron microscope, a columnar structure is inclined and formed on the substrate. The liquid crystal is considered to be arranged by this columnar structure. In addition to SiO, SiO ₂ may be used. Other inorganic substances that form columnar structures can also be used.

  In the present invention, circularly polarized light is incident on the liquid crystal shutter 120. Then, by making the circularly polarized light incident in this way, it becomes possible to obtain a constant transmittance regardless of variations in the molecular tilt direction.

  FIG. 3 schematically shows a liquid crystal display device of the present invention, which includes an optical system for applying circularly polarized light to the liquid crystal element. In FIG. 3, reference numeral 50 denotes a light source, and the light source 50 is a commonly used extra-high pressure mercury lamp.

  As shown in FIG. 3, the light L <b> 1 emitted from the light source 50 is bent at a right angle by the semi-transmissive plate 55 and is incident on the liquid crystal element 120. Here, the light of the ultrahigh pressure mercury lamp which is the light source 50 has a random polarization plane. Further, the circularly polarizing means 53 is placed above the liquid crystal element 120, so that the light transmitted through the circularly polarizing means 53 becomes circularly polarized light.

  As shown in FIG. 4, the circularly polarizing means 53 is a laminate of a linearly polarizing plate 51 and a λ / 4 plate 52, and a transmission axis 511 of the linearly polarizing plate 51 and a delay of the λ / 4 plate 52. The phase axis 512 (the axis that causes the largest phase delay in the transmitted light) forms an angle of 45 °. As a result, light entering from the side of the linear polarizing plate 51 becomes right circularly polarized light and exits from the λ / 4 plate 52.

  Here, if necessary, a half-wave plate (λ / 2 plate) (not shown) is laminated so that it can be converted into circularly polarized light in a wide-band wavelength region over the entire visible light. At this time, the optical axis of the λ / 2 plate is arranged to make an angle of 15 degrees from the polarization axis, and the optical axis of the λ / 4 plate is arranged to make an angle of 75 degrees from the polarization axis. It is preferable. Alternatively, a broadband quarter-wave plate having so-called reverse dispersion characteristics may be used with its optical axis forming an angle of 45 degrees from the polarization axis.

  In the liquid crystal display device having such a circular polarization means 53, when the liquid crystal molecules are aligned perpendicular to the substrate, the incident light L1 shown in FIG. 3 is reflected without being modulated by the liquid crystal layer. Come out as it is. At this time, since the reflection surface is constituted by the metal electrode 126, there is no phase change due to reflection. Therefore, the reflected light is counterclockwise left circularly polarized light.

  Thereafter, the light L2 emitted from the liquid crystal element 120 is again a quarter-wave plate (λ / 4 plate) 52 (or a retardation plate in which a quarter-wave plate and a half-wave plate are stacked). ) And is left circularly polarized light, so that it becomes linearly polarized light whose polarization plane is orthogonal to that at the time of incidence. As a result, the light is absorbed by the linearly polarizing plate 51, and the light does not come out above the circularly polarizing means 53.

  On the other hand, when a voltage is applied to the liquid crystal element 120, liquid crystal molecules are tilted with respect to the substrate, and the liquid crystal element 120 has optical anisotropy about the tilt direction. Here, consider a case where circularly polarized light is vertically incident on the liquid crystal element. When the circularly polarized light is divided into two components, that is, the optical axis and an axis perpendicular to the optical axis, the component in the optical axis direction causes a phase lag compared to the component orthogonal thereto.

  When the refractive index anisotropy of the liquid crystal and the thickness of the liquid crystal layer are optimally selected, when the brightest display is obtained, the light that is reflected is 180 ° with respect to the component whose optical axis direction component is orthogonal thereto. Is causing a delay. When the two components of the emitted light are recombined, the traveling direction is opposite, but the right circularly polarized light is the same as the incident light.

  The above description does not depend on the angle between the optical axis of the liquid crystal element 120 and the transmission axis of the linear polarizing plate 51 or the slow axis of the λ / 4 plate. Therefore, even if the direction of the optical axis is different, the right circularly polarized light of the incident light is always emitted as right circularly polarized light. Similarly, when the incident light is left circularly polarized light, the outgoing light is left circularly polarized light.

  Note that the light that has been right-circularly polarized and has left the liquid crystal element 120 becomes linearly polarized light having the same polarization plane as the incident light by the λ / 4 plate 52 and is transmitted through the linearly polarizing plate 51. This enters the upper magnifying optical system (not shown) through the semi-transmissive plate 55, is enlarged, and is projected onto the screen (not shown).

  By the way, the inclined surface of the liquid crystal when a voltage is applied to the liquid crystal element 120 is determined by the deposition direction of the liquid crystal alignment film, and thus varies depending on the chip. However, as described above, when the liquid crystal element 120 is irradiated with circularly polarized light, the same polarization modulation can be obtained regardless of the tilt direction of the liquid crystal molecules. This eliminates the need for adjusting the optical system for each chip and simplifies the adjustment of performance during manufacturing.

  In addition, as a projection-type liquid crystal display device using a plurality (usually three) of liquid crystal elements 120, the adoption of this method is effective because all three liquid crystal elements have characteristics with little variation.

  As described above, the quarter-wave plate (λ / 4 plate) 52 that polarizes the incident light from the light source 50 converts the light from the light source 50 into elliptically polarized light or circularly polarized light and irradiates the liquid crystal element 120. Thus, a display device independent of the optical axis direction of the liquid crystal element can be realized.

  As the liquid crystal element using circularly polarized light according to the present embodiment described above, a transmissive liquid crystal element can also be used. In that case, it is necessary to place circularly polarizing means on both the outgoing side and the incoming side of the liquid crystal element 120.

  Further, the present invention can be applied to a direct-view display instead of the configuration of the projection type liquid crystal display device using the magnifying optical system. In this case, the entire substrate may be used as one liquid crystal element, or the substrate may be divided into smaller sizes and used as liquid crystal elements. Furthermore, the fragment | piece of the arbitrary positions divided | segmented can be used as a liquid crystal element.

  Heretofore, examples of the vertical alignment mode have been shown as the liquid crystal mode, but various alignment modes such as a parallel alignment mode, a HAN (hybrid alignment with different top and bottom pretilts) mode, and an OCB mode can be used in the present invention. Furthermore, it may have a slight twisted orientation as long as it does not adversely affect the optical characteristics. Further, depending on the liquid crystal mode, an oblique deposition alignment film may be provided only on one substrate.

  In addition, although an example using circularly polarized light instead of linearly polarized light has been shown so far, even if it is not completely circularly polarized light, an improvement effect can be obtained even when elliptically polarized light is used compared with the case where linearly polarized light is used. Is possible.

  As a colorization method, a color filter may be used, or a time display color display method may be used.

  Even in the case of a projection type liquid crystal display device using a plurality of liquid crystal elements, that is, a so-called three-plate type projection liquid crystal display device using three liquid crystal elements that modulate light of red, green, and blue. The film forming method and optical system described in detail in the book can be used.

  For example, in the conventional apparatus, when the direction of the easy orientation axis is deviated by about 1 degree with respect to the set value, the transmitted light intensity changes by nearly 1%. Thus, for example, when red becomes 1% brighter and blue becomes 1% darker, the color temperature is displayed lower, and conversely, for example, when red becomes 1% darker and blue becomes 1% brighter, the color temperature becomes lower. The display will be higher. As a result, when the two products are observed and compared side by side, the white balance is different, and reproducibility as a product cannot be obtained. In other words, in the conventional optical system, when the product is strictly managed, it is considered that the easy axis of orientation cannot accept a deviation of about 1 degree.

  On the other hand, in the present invention, it is possible to obtain almost the same optical characteristics even with respect to an element having an easy-orientation axis distribution that is shifted by 1 degree or more, that is, a distribution of easy-orientation axes generated when using a general-purpose vapor deposition apparatus Application to the product is acceptable. This is effective for reducing the manufacturing process load and thus for reducing the cost. This also makes it possible to obtain a projection type liquid crystal display device with good color reproducibility.

  As described above, the oblique vapor deposition method has been described as an example, but there are various methods such as an oblique sputtering method, an alignment control by a photo-alignment film using an ultraviolet point light source, and a method of controlling the surface shape by a sandblast or an ion beam. The present invention can be applied to the orientation control method.

  By the way, even if a slit is provided, a distribution occurs in the plane in the deposition angle in the deposition from the point source. Next, this cause will be described with reference to FIG. 2 and FIG. 5 which is a modification of FIG. 2 described above.

  The vapor deposition apparatus shown in FIG. 2 includes a vacuum vessel 6, a vapor deposition source 5 and a slit 4 fixedly arranged in the vacuum vessel 6, and the substrate 1 moves in a certain direction. Here, the slit 4 extends in parallel to the surface of the substrate 1, that is, perpendicular to the paper surface. During the deposition, the substrate 1 is perpendicular to the extending direction of the slit 4, that is, the longitudinal direction, and parallel to the surface. Moving.

  Then, the SiO beam that is evaporated from the evaporation source 5 passes through the slit 4 and enters the substrate 1 obliquely. 2 is an angle formed by the shortest distance vector 4 between the vapor deposition source 5 and the substrate 1 and the substrate normal 2.

  The vapor deposition apparatus shown in FIG. 5 is of a type in which the angular relationship between the vapor deposition source 5 and the substrate 1 is the same as that in FIG. 2, and the substrate 1 is moved in a direction perpendicular to the vapor deposition beam. In FIG. 5, the movement direction of the substrate 1 is on the x axis.

  2 and 5, the angle formed between the substrate 1 and the deposited material radiated from the deposition source 5 through the slit 4 is constant.

  However, the vapor deposition angle θ is constant only for the vapor deposition material passing through the slit at right angles to the longitudinal direction, and the vapor deposition angle and the vapor deposition direction are shifted for the vapor deposition material passing through the slit 4 diagonally. Here, FIG. 6 shows the arrangement of FIG. 5 as viewed from the x-axis direction. As shown in FIG. 6, since the deposit from the deposition source 5 spreads radially, the growth direction of the column has a distribution. become.

The maximum deviation in the vapor deposition azimuth direction, that is, the distribution amount θ _A1 can be expressed by the following equation (1).

r is the radius of the substrate 1, h is the distance from the deposition source 5 to the center of the substrate, and Θ is the deposition angle at the center of the substrate. FIG. 7 illustrates the relationship between h and the distribution amount θ _A1 when the substrate size is 8 inches (radius r = 10 cm) and the deposition angle Θ at the center of the substrate is 60 °.

  According to FIG. 7, it can be seen that the distance from the deposition source 5 to the substrate 1 must be 6 meters or more in order to make the variation amount in the easy axis direction 1 ° or less. That is, in order to reduce the variation in the column direction, that is, the easy axis direction of the liquid crystal in the oblique vapor deposition method, it is necessary to make the distance from the vapor deposition source 5 to the substrate 1 extremely large.

  If the vapor deposition angle θ at a position r apart from the center line of the substrate is also strictly calculated, it depends on r as described below and has variations in the substrate plane.

  This is illustrated in FIG. According to FIG. 8, when the distance from the vapor deposition source 5 to the substrate 1 is 1 m or more, the variation of the vapor deposition angle is within 1 °. If an apparatus in which the distance between the vapor deposition source 5 and the substrate 1 is about 1 meter is used, the vapor deposition angle Θ can be regarded as substantially constant.

  9 and 10 are formed by extending the slit 4 in the direction intersecting the surface of the substrate 1, that is, in the X-axis direction for comparison. Evaporation is performed on the entire surface of the substrate by moving the substrate 1 in the y-axis direction. If the slit 4 is installed in such a direction, the variation in the in-plane azimuth distribution is eliminated.

  However, as shown in FIG. 9, the deposition angle is distributed along the slit, and as a result, the pretilt angle of the liquid crystal molecules varies in the substrate plane.

  The distribution width of the vapor deposition angle can be expressed by the following formula, where the vapor deposition angle at the center of the substrate 1 is Θ.

  FIG. 11 is a diagram showing the relationship between the distance h between the vapor deposition source 5 and the substrate center represented by the formula (3) and the vapor deposition angle θ. θ1 is a plot of the lower limit of θ, ie, the left side of equation (3), and θ2 is a plot of the upper limit of θ, ie, the right side of equation (3).

  From FIG. 11, it can be seen that when the variation in the deposition angle is within 1 degree, h must be 300 cm or more. Even if the slit formation direction is changed in this way, in order to reduce the variation in the pretilt angle, it is necessary to make the distance from the vapor deposition source 5 to the substrate 1 extremely large. Such a vapor deposition apparatus is difficult to maintain a vacuum, and the maintenance of the apparatus is also considered difficult.

  Further, when compared with the same value of h, the variation in the deposition angle in FIG. 11 is much larger than that in FIG. This means that the variation in the pretilt angle when vapor deposition is performed in the arrangement of FIGS. 9 and 10 is larger than that in the arrangements of FIGS.

  As shown in FIG. 15 described above, when the pretilt angle varies, the optical response characteristics such as the threshold voltage and the voltage that gives the maximum reflectance change greatly. Therefore, although the vapor deposition methods of FIGS. 9 and 10 have the advantage of aligning the tilt azimuth angles of the liquid crystals, the optical characteristics vary greatly depending on the pretilt angle, which is disadvantageous than the methods of FIGS.

  If the liquid crystal molecules have a twisted structure when tilted, the optical characteristics change according to the twist angle. In order to avoid this, it is effective to keep one substrate in a completely vertical orientation.

  If one substrate is a completely vertically aligned substrate A and the other substrate is a substrate B with a variation in the deposition angle within the substrate plane, the tilt direction of the liquid crystal is determined by the substrate B, and the alignment film of the substrate A It will not be affected. Thereby, the liquid crystal molecules can be aligned without forming a twist, and only the tilt azimuth angle can be varied depending on the element.

  In the present invention, since the tilt azimuth angle does not affect the optical characteristics by using circularly polarized light, by employing the combination of the substrates A and B, it is possible to obtain a liquid crystal element that does not cause any variation in optical characteristics. It becomes possible.

  As described above, by using circularly polarized light to irradiate the liquid crystal element, it is possible to eliminate the influence of the in-plane azimuth angle on the optical characteristics, and a large area process by oblique deposition is possible. In addition, since the variation in the tilt azimuth angle of the liquid crystal within the substrate surface can be ignored, the size of the vapor deposition apparatus can be reduced. As a result, a liquid crystal manufacturing process with low cost and high productivity can be realized. Since an inorganic material alignment film such as SiO can be used, durability against strong light irradiation is improved.

  In other words, by converting incident light from the light source into circularly polarized light and irradiating the liquid crystal element, even if there is a deviation in the optical axis due to variations in the deposition angle, a high-quality image can be displayed without reducing the contrast. Can do.

  Furthermore, since there may be fluctuations in the vapor deposition direction, during vapor deposition, it is possible to select a vapor deposition method that allows a wide variation in vapor deposition direction and reduces the fluctuation in vapor deposition angle, resulting in variations in pretilt angle. Can be kept low. Further, since the yield of the chip can be increased, the manufacturing cost of the liquid crystal shutter can be reduced, and a low-cost liquid crystal display device can be provided.

  Hereinafter, the present invention will be described in detail using examples.

(Configuration and manufacturing method of liquid crystal display device common to all embodiments)
As the liquid crystal element 120 shown in FIG. 1, a liquid crystal material having a negative dielectric anisotropy Δε (Merck, model name: MLC-6608) is used, and the cell thickness of the liquid crystal layer 124 is 3.5 microns. The substrates 121 and 127 were 8 inches in diameter. The substrate may be a silicon wafer or a glass substrate. You may combine the two. On one substrate, a circuit for driving the liquid crystal is built in advance.

  A method for manufacturing the liquid crystal element 120 is as follows.

  An SiO alignment film is formed on the entire surface of the substrate by oblique deposition shown in the following examples. One substrate may be subjected to another alignment treatment so as to have vertical alignment. Next, the two substrates 121 and 127 are bonded to each other with the surfaces with the alignment films facing each other to form cells. At this time, one substrate is reversed with respect to the vapor deposition axis and bonded to the other so that the vapor deposition directions of the two substrates are aligned. When one of the substrates is vertically aligned and does not have directionality, it is not necessary to match the orientation.

  This is cut into a predetermined size to form a plurality of cells, liquid crystal is injected, sealed, and then connected to a peripheral circuit to complete the liquid crystal element 120. The liquid crystal element 120 thus manufactured is incorporated into a projection optical device including a circularly polarizing plate to obtain a liquid crystal display device.

  At the time of incorporation, the position is adjusted so that the arrangement of circuits and pixels previously formed on the substrate is in the correct orientation with respect to the optical device. At this time, the alignment orientation of the liquid crystal does not affect the optical characteristics at all, and therefore, it is not necessary to consider the attachment of the liquid crystal element to the optical device.

Example 1
In this embodiment, alignment films 123 and 125 are formed by a vapor deposition apparatus shown in FIG. 2 to produce a liquid crystal element. At this time, the distance between the vapor deposition source 5 and the substrate 1 is 1 meter. And it is set as a projection type liquid crystal display device using this liquid crystal element.

  As an optical system of a projection-type liquid crystal display device, two types are compared, one in which linearly polarized light is incident on a liquid crystal element and the other in which circularly polarized light is incident.

  In the projection type liquid crystal display device using linearly polarized light, the contract varies depending on the attached liquid crystal element, while the projection type liquid crystal display device using circularly polarized light has a stable display with almost no variation.

(Example 2)
In this embodiment, the alignment film of one substrate is formed by the vapor deposition apparatus shown in FIG. 2, and the remaining one substrate is placed in the direction shown by the arrow 8 during the vapor deposition shown in FIG. An alignment film that is vertically aligned is formed by a constant-velocity oblique vapor deposition method that rotates at a constant speed. Note that the distance between the evaporation source and the substrate is 1 meter in any film formation. A projection type liquid crystal display device is assembled using the liquid crystal element thus produced.

  Circularly polarized light is used as polarized light incident on the liquid crystal element. As a result, a highly uniform image can be obtained with no variation in display image due to the liquid crystal element.

(Example 3)
In this embodiment, an optical system shown in FIG. 13 is used instead of the optical system shown in FIG.

  In FIG. 13, the light emitted from the light source 50 passes through the linear polarizer 51 and is converted into linearly polarized light, and further passes through a quarter-wave plate (λ / 4 plate) 52 to be converted into circularly polarized light. Is done. Thereby, the liquid crystal element 120 is irradiated with circularly polarized light.

  In the case of an alignment state in which there is no retardation of the liquid crystal layer, the light is reflected in a circularly polarized state by a reflecting plate (not shown) built in the liquid crystal element 120. When this circularly polarized light passes through the λ / 4 plate 52 again, the circularly polarized light is converted into linearly polarized light. At this time, the polarization direction of the linearly polarized light is a polarization state in a direction orthogonal to the incident polarized light. Thereafter, the light reaches the polarizing plate 51, but since the direction of the incident polarized light is the direction of the absorption axis of the polarizing plate 51, the light does not come out. That is, it is a black state.

  On the other hand, when the alignment state is such that the retardation of the liquid crystal layer satisfies the λ / 4 condition, light traveling back and forth through the liquid crystal layer undergoes modulation under the λ / 2 condition. That is, the polarization state of the incident circularly polarized light is opposite to the circularly polarized light as compared with the case where there is no retardation in the liquid crystal layer due to the liquid crystal layer having the retardation of λ / 2 condition.

  In this state, the circularly polarized light is converted into linearly polarized light by passing through the λ / 4 plate 52 again. At this time, the polarization direction of the linearly polarized light is a polarization state in a direction matching the incident polarized light. Thereafter, the light reaches the polarizing plate 51, but since the direction of the incident polarized light is the direction of the transmission axis of the polarizing plate 51, the light can come out. That is, it is a white state.

  Also, a halftone state can be created by controlling the retardation of the liquid crystal layer to an intermediate alignment state between zero and λ / 4 conditions.

  In this way, brightness can be modulated.

Example 4
FIG. 14 shows a three-plate projection type liquid crystal display device provided with three liquid crystal elements that respectively modulate RGB three primary colors. The light emitted from the light source 50 is transmitted only through R, G and B are transmitted through only the reflecting dichroic mirrors 60 and B, and R and G are separated into three colors of RGB by the reflecting dichroic mirror 61 and the total reflection plate 62. The light enters the three liquid crystal elements 120R, 120G, and 120B.

  On the incident side of the liquid crystal element, circularly polarizing means 53R, 53G, and 53B each having a structure shown in FIG. 14 are arranged to convert incident light into clockwise circularly polarized light. When no voltage is applied, the liquid crystal transmits right circularly polarized light as it is, and the liquid crystal tilts according to the voltage to modulate incident light. Since the phase shift of λ / 2 is given at the maximum voltage, the left circularly polarized light is emitted.

  Circular polarization means 53R ', 53G', and 53B 'having a configuration in which the front and rear in FIG. 4 are reversed are also disposed on the emission side of the liquid crystal element. Right circularly polarized light emitted from the liquid crystal element to which no voltage is applied is converted into linearly polarized light having a polarization plane perpendicular to the original linearly polarized light by the λ / 4 plate in front, so that it is absorbed by the linearly polarized light plate. And there is no light over there. The left circularly polarized light emitted from the liquid crystal element to which the maximum voltage is applied is converted into linearly polarized light having a polarization plane parallel to the original linearly polarized light by the λ / 4 plate in front, so that it passes through the linearly polarizing plate. Go out the other side.

  The light emitted from each liquid crystal element is again synthesized by the dichroic mirrors 60 and 61 and the total reflection plate 62 and projected onto the screen 64 by the projection optical system 63.

  All of the three liquid crystal elements are made using an obliquely deposited film of SiO. Since each of the three sheets is provided with circularly polarizing means, even if the optical axis is deviated, the characteristic does not become non-uniform, and an image with a stable color tone can be obtained.

  By applying an antireflection treatment (anti-reflection: AR treatment) to the surface of the polarizing plate, surface reflection can be suppressed and the contrast ratio can be increased.

  It is possible to obtain a higher contrast by matching the wavelength region with the highest antireflection effect, that is, the center wavelength of the AR treatment with the display color of the liquid crystal element used as the three-plate liquid crystal element as the AR treatment condition to be used. It becomes.

  In addition to the AR process, an anti-glare process can be used in combination to further provide an antireflection effect and obtain a high contrast.

(Comparative example)
In this comparative example, an alignment film is formed by the vapor deposition apparatus shown in FIGS. 9 and 10 to produce a liquid crystal element. At this time, the distance between the evaporation source and the substrate is 1 meter. A projection type liquid crystal display device is formed using this liquid crystal element.

  Next, in the optical system used for the projection-type liquid crystal display device, a comparison is made between two types of polarized light to be incident on the liquid crystal element: linearly polarized light and circularly polarized light. Here, in any of these liquid crystal display devices, when an image is observed, a color shift or an in-plane distribution of color display occurs, and a display with high display quality cannot be obtained.

FIG. 3 is a diagram illustrating a configuration of a liquid crystal shutter which is an example of a liquid crystal device (liquid crystal display element) provided in a liquid crystal display device according to an embodiment of the present invention. The figure explaining the structure of the vapor deposition apparatus provided in the manufacturing apparatus of the liquid crystal display device which manufactures the said liquid crystal display device. FIG. 4 is a diagram illustrating an example of an optical system used in the liquid crystal display device. The figure which shows the structure of the circularly-polarizing means provided in the said optical system. The figure explaining other structures of the said vapor deposition apparatus. The side view of FIG. The figure which shows the relationship between the distance from a vapor deposition source, and the dispersion | variation in a vapor deposition angle. The figure which shows the relationship between the distance from a vapor deposition source, and the dispersion | variation in a vapor deposition angle. The figure explaining the structure of the manufacturing apparatus which concerns on the comparative example of the said manufacturing apparatus. The side view of FIG. The figure explaining the relationship between the distance from a vapor deposition source, and the dispersion | variation in a vapor deposition angle. The figure which shows the constant velocity rotation oblique vapor deposition method used for the Example of this invention. FIG. 6 is a diagram showing an optical system according to Example 3 of the present invention. The figure which shows the structure of the liquid crystal display device which concerns on Example 4 of this invention. The figure which shows the relationship between a pretilt angle and an optical optical response characteristic. The figure which shows the relationship between vapor deposition direction and an optical response characteristic.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Tilt angle 3 Mask 4 Slit 5 Evaporation source 7 Evaporation direction 8 Substrate rotation direction 50 Light source 51 Linearly polarizing plate 511 Transmission axis 512 Slow axis 52 1/4 wavelength plate (λ / 4 plate)
53 Circular polarization means 120 Liquid crystal element 121, 127 Substrate 122, 126 Electrode 123, 125 Alignment film 124 Liquid crystal layer L1 Incident light L2 Emitted light

Claims (8)

A liquid crystal element including a pair of substrates, an alignment film made of an inclined columnar structure of an inorganic material, and a liquid crystal disposed between the pair of substrates, provided on at least one of the pair of substrates; And a liquid crystal display device that modulates and emits light from the light source,
A liquid crystal display device comprising: circularly polarizing means for converting light from the light source into circularly polarized light or elliptically polarized light and entering the liquid crystal element.   2. A liquid crystal display device according to claim 1, wherein the circularly polarizing means comprises a linearly polarizing plate and a [lambda] / 4 plate.   The liquid crystal element includes a reflecting means, and when the voltage is not applied, the incident circularly polarized light or elliptically polarized light is reflected as a reversely rotated circularly polarized light or elliptically polarized light. 3. The liquid crystal display device according to claim 1, wherein the elliptically polarized light is reflected as circularly polarized light or elliptically polarized light having the same rotation.   4. The liquid crystal display device according to claim 3, wherein the light reflected by the reflecting means is emitted through the λ / 4 plate and the linearly polarizing plate.   5. The liquid crystal display device according to claim 3, wherein the reflecting means is a metal electrode provided on a substrate opposite to the viewer side of the pair of substrates.   The liquid crystal display device according to claim 1, comprising a plurality of liquid crystal elements.   7. The liquid crystal display device according to claim 1, wherein one of the pair of substrates is a silicon substrate. A liquid crystal element including a pair of substrates, an alignment film made of an inclined columnar structure of an inorganic material, and a liquid crystal disposed between the pair of substrates, provided on at least one of the pair of substrates; A method of manufacturing a liquid crystal display device that modulates and emits light from the light source,
In a plane parallel to the slit in the vacuum vessel in which the vapor deposition source and the slit are arranged, the step of arranging the substrate inclined with respect to a line connecting the vapor deposition source and the slit;
Irradiating the substrate with an evaporant from the vapor deposition source through the slit;
Moving the substrate perpendicularly to the direction of extension of the slit;
Bonding the substrate to another substrate;
Cutting the two bonded substrates into a plurality of cells;
Injecting liquid crystal into the cell;
Attaching the cell into which the liquid crystal has been injected to an optical device including circularly polarizing means;
A method of manufacturing a liquid crystal display device, comprising:

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