JP2012194378A - Image control device and image display system - Google Patents

Abstract

An image display technique capable of realizing good stereoscopic display is provided.
An image control device is used in combination with an image display device that alternately displays a first image and a second image, and corresponds to an optical element and a switching timing of the first image and the second image. And an optical element driving unit for driving the optical element. The optical element includes a first substrate and a second substrate, a first electrode provided on the first substrate, a prism array having a plurality of prisms provided on the first substrate, and a first electrode and a prism array. The first alignment film provided on the upper side, the second electrode provided on the second substrate, the second alignment film provided on the upper side of the second electrode, and provided between the first substrate and the second substrate A liquid crystal layer.
[Selection] Figure 5

Description

  The present invention relates to an image display technique for allowing a user to perceive a stereoscopic display.

  An image display system that allows a user to visually recognize a three-dimensional image (so-called 3D image) is becoming popular. Methods for realizing stereoscopic image display are roughly classified into a method using stereoscopic display glasses configured using a liquid crystal shutter and the like and a method not using such stereoscopic display glasses.

  Examples of methods that do not use stereoscopic display glasses include a lenticular lens method and a parallax barrier method. In any of these methods, a right-eye image and a left-eye image are created spatially, and a user visually recognizes each image from a predetermined position so that a stereoscopic image can be obtained.

  The above lenticular lens method is a method in which a left-eye image and a right-eye image reproduced on a display are separated and incident separately on the left and right eyes using a semi-cylindrical lens group called a lenticular. The parallax barrier method described above is a method in which a parallax barrier having a small hole or slit is arranged on the front of the display so that the right eye image and the left eye image are separated and separately incident on the left and right eyes. is there.

  However, in the lenticular lens system, there is still room for improvement in that the user can view stereoscopically only at a predetermined position and that the entire configuration of the image display system and video software are expensive. In addition, in both the lenticular lens system and the parallax barrier system, there is a problem that it is difficult to increase the resolution of the image. Specifically, when the number of pixels of the display is considered to be constant, the resolution is halved with the binocular system and 1 / ( The number of multiple eyes).

  On the other hand, as a method of using 3D display glasses, Japanese Patent Application Laid-Open No. 5-257083 (Patent Document 1) discloses polarizing glasses in which polarizing plates having polarization directions different from each other by 90 ° are bonded so as to match the left and right eyes. The stereoscopic display technique used is disclosed. Japanese Laid-Open Patent Publication No. 6-178325 (Patent Document 2) discloses a stereoscopic display technique using liquid crystal shutter glasses that open and close left and right shutters in synchronization with left and right images for stereoscopic display.

  However, in the prior example represented by Patent Document 1, since the right image and the left image are formed by using every other pixel column in the liquid crystal panel, there is a disadvantage that the resolution of the display image is lowered. In addition, as one of stereoscopic display technologies using such polarized glasses, there is one using an expensive optical film configured by regularly arranging fine polarizing elements. However, in that case, it is necessary to attach the optical film to the outgoing light side of a display device such as a liquid crystal panel with high accuracy, and the installation of the optical film is not easy. Further, the polarizing glasses have a low transmittance, and there is a disadvantage that the user feels dark when viewing other than the image. The prior art represented by Patent Document 2 is an excellent technique that can be widely applied to display devices of a system other than the liquid crystal display device, but the liquid crystal shutter glasses have a low transmittance as described above. Even if the transmittance is relatively high, it is 45% or less, and if it is low, it is 30% or less. There is also the inconvenience that the user feels dark when viewing images or other images.

JP-A-5-257083 JP-A-6-178325

  A specific aspect according to the present invention is to solve the above-described problems and to provide an image display technique capable of realizing good stereoscopic display.

  An image control apparatus according to an aspect of the present invention is an image control apparatus used in combination with an image display apparatus that alternately displays a first image and a second image, and includes: (a) an optical element; An optical element driving unit that drives the optical element in response to the switching timing of the first image and the second image by the image display device is provided. The optical element includes: (c) a first substrate and a second substrate disposed to face each other; (d) a first electrode provided on the first substrate and connected to the optical element driving unit; e) a prism array having a plurality of prisms provided on the first substrate; (f) a first alignment film provided on the first electrode and the prism array; and (g) the second substrate. A second electrode connected to the optical element driving unit; (h) a second alignment film provided on the upper side of the second electrode; and (i) the first alignment of the first substrate. A liquid crystal layer provided between the film and the second alignment film of the second substrate;

  In the above image control device, when the alignment of the liquid crystal molecules is changed by applying a voltage to the liquid crystal layer via the first electrode and the second electrode, the refractive index of the liquid crystal layer changes. At this time, the refraction angle of light transmitted through the interface between the prism array having a minute slope and the liquid crystal layer can be changed. Based on this action, by appropriately setting the magnitude of the voltage applied to the liquid crystal layer, the viewing angle direction of the display image of the image display device viewed through the optical element can be freely controlled. By driving such an optical element in accordance with the switching timing of the first image (for example, the image for the right eye) and the second image (for example, the image for the left eye) by the image display device, one eye of the user (for example, the right eye) ) And the second image can be displayed in the direction of another eye (for example, the left eye). Thereby, it becomes possible to make a user visually recognize a three-dimensional image. Since the optical element in the image control apparatus can have a transmittance of 90% or more even when an antireflection film is used, the user does not feel darkness. Moreover, since glasses are not required, it is advantageous in terms of cost and user convenience. In principle, the resolution is not lowered as in the lenticular lens system and the parallax barrier system. Therefore, according to the above-described image control apparatus, it is possible to eliminate inconveniences in the previous example and realize a good stereoscopic display.

  In the image control apparatus, the optical element driving unit supplies a relatively high voltage to the optical element, for example, when the first image is displayed, and is relative to the optical element, when the second image is displayed. Supply a low voltage. The “relatively low voltage” here includes 0 volt.

  In the image control apparatus, the optical element is disposed, for example, on the front side of the image display apparatus. For example, when the image display device is a liquid crystal display device having a liquid crystal display panel, an optical element may be disposed on the rear surface side of the liquid crystal display panel.

  By arranging the optical element in the front face, it becomes easy to install the optical element externally to the image display apparatus.

  In the image control device, the image display device is preferably a liquid crystal display device having a directional backlight.

  Thereby, the separability between the first image and the second image is further increased, and the effect of suppressing so-called crosstalk is enhanced.

  In the above-described image control apparatus, it is also a preferable aspect that the prism array has different inclination angles of the prisms along an arrangement direction of the plurality of prisms.

  As a result, the refraction angle of light in the optical element can be gradually increased (or decreased), so that the visibility of the image to the user can be improved even when the size of the image display device is relatively large. It becomes possible.

It is a block diagram which shows the structure of the image display system of one Embodiment. It is typical sectional drawing which shows the structure of a liquid crystal display panel and an optical element. It is a typical perspective view of a prism array. It is a figure for demonstrating the relationship between the polarization direction of the emitted light of an image display panel, and the direction of the orientation process in an optical element. It is a figure for demonstrating the mode of the image control by an optical element. It is typical sectional drawing which shows the other structural example of an optical element. It is typical sectional drawing which shows the other structural example of a prism array.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration of an image display system according to an embodiment. An image display system 100 shown in FIG. 1 includes a liquid crystal display panel (LCD) 1, a liquid crystal driving unit (LCD driving unit) 2, a backlight 3, an optical element 5, and an optical element driving unit 6. In this embodiment, the optical element 5 and the optical element driving unit 6 correspond to an “image control device”, and the liquid crystal display panel 1, the liquid crystal driving unit 2, and the backlight 3 correspond to an “image display device”. In the illustrated example, the optical element 5 is arranged on the front side of the liquid crystal display panel 1 with the user 200 as a reference. The optical element 5 is disposed in close contact with the liquid crystal display panel 1 as shown in the figure, for example.

  The liquid crystal display panel 1 displays an image (moving image or still image) based on the image signal given from the liquid crystal driving unit 2. The liquid crystal display panel 1 has a known structure, and a backlight 3 is disposed on the back side thereof.

  The liquid crystal driving unit 2 supplies an image signal to the liquid crystal display panel 1 to cause the liquid crystal display panel 1 to alternately display a right eye image (first image) and a left eye image (second image). The switching cycle between the right-eye image and the left-eye image is, for example, 60 Hz (frame rate 60 fps).

  The backlight 3 is disposed on the back side of the liquid crystal display panel 1 and makes light incident on the liquid crystal display panel 1.

  The optical element 5 is a thin plate-like element that is substantially transparent in appearance, and is disposed on the front side of the liquid crystal display panel 1. The optical element 5 freely controls the state of light emitted from the liquid crystal display panel 1 in accordance with a drive signal supplied from the optical element driving unit 6. Thereby, the viewing angle direction of the display image visually recognized by the user 200 can be freely controlled. Note that the optical element 5 of the present embodiment has a high transmittance in principle because a polarizing plate is not required unlike a general liquid crystal element. Specifically, 90% or more is expected as the transmittance of the optical element itself, and when an antireflection coating (AR coating) is applied to the surface of the optical element 5, a transmittance of 95% or more is expected.

  The optical element driving unit 6 drives the optical element 5 in accordance with the switching timing of the right eye image and the left eye image by the liquid crystal display panel 1. Specifically, the optical element driving unit 6 supplies, for example, a relatively high voltage to the optical element 5 in synchronization with the display of the right-eye image, and relatively to the optical element 5 in synchronization with the display of the left-eye image. Supply a low voltage. The “relatively low voltage” here includes 0 volt.

  FIG. 2 is a schematic cross-sectional view showing the structure of the optical element and the backlight. In FIG. 2, for the sake of convenience, hatching is omitted except for some components (the same applies to the drawings described later). As shown in the figure, the backlight 3 and the optical element 5 are disposed with the liquid crystal display panel 1 sandwiched therebetween, the optical element 5 is disposed on the front side (light emitting side) of the liquid crystal display panel 1, and the backlight 3 is liquid crystal. The display panel 1 is disposed on the rear surface side (light incident side).

  The backlight 3 of the present embodiment shown in FIG. 2 includes a light guide plate 31, an LED light source 32, and a hologram diffusion plate 33. The backlight 3 of the present embodiment is a backlight having directivity for the emitted light (directional backlight). Such a directional backlight structure is disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-142078.

  The light guide plate 31 is a flat member formed using a translucent material (for example, a transparent acrylic resin). The light guide plate 31 includes a surface having a groove-shaped uneven portion (knurl) 31 a formed by arranging a plurality of inclined surfaces and another surface facing the surface, and the other surface is closer to the liquid crystal display panel 1. It is arranged toward. In addition, the light guide plate 31 includes a light introducing portion 31b for introducing light emitted from the LED light source 32 at an end thereof.

  The uneven portion 31a of the light guide plate 31 is for reflecting the light emitted from the LED light source 32 and changing the traveling direction thereof. The inclination angle (knurling inclination angle) of each inclined surface of the uneven portion 31a is, for example, about 2 ° to 20 °, more preferably about 3 ° to 11 °.

  The light introduction part 31b of the light guide plate 31 has, for example, a peripheral part of a cross-sectional shape of a hyperbola (or a circle, an ellipse, a parabola, etc.) having the same central axis as the optical axis of the opposing LED light source 32, and a cross section different from this peripheral part. The lens has a central portion of the shape and is Fresnelized.

  The LED light source 32 is disposed in the vicinity of the light introducing portion 31 b at the end of the light guide plate 31 and makes light incident on the light guide plate 31. The distance between the light introducing portion of the light guide plate 31 and the LED light source 32 is set to about 0.1 mm, for example.

  The hologram diffusion plate 33 is disposed between the light guide plate 31 and the liquid crystal display panel 1.

  The optical element 5 of this embodiment shown in FIG. 2 includes a first substrate 51, a first electrode 52, a prism array 53, a first alignment film 54, a second substrate 55, a second electrode 56, a second alignment film 57, and a liquid crystal. A layer 58 is included.

  The first substrate 51 and the second substrate 55 are arranged to face each other, and are transparent substrates such as a glass substrate and a plastic substrate, respectively. Between the first substrate 51 and the second substrate 55, for example, a large number of spacers (granular bodies) are distributed (not shown), and the first substrate 51 and the second substrate are arranged by these spacers. The mutual space | interval with 55 is maintained.

  The first electrode 52 is provided on one surface side of the first substrate 51. Similarly, the second electrode 56 is provided on one surface side of the second substrate 55. The first electrode 52 and the second electrode 56 are each configured using a transparent conductive film such as indium tin oxide (ITO). For example, in the present embodiment, both the first electrode 52 and the second electrode 56 are formed on the entire surface of the substrate. The first electrode 52 and the second electrode 56 may be appropriately patterned.

  The prism array 53 is configured by arranging a plurality of minute inclined projection shapes (prisms) in one direction. A schematic perspective view of the prism array 53 is shown in FIG. As shown in the drawing, the cross-sectional shape of each prism is a right triangle (for example, a vertical angle of 75 ° and a base angle of 15 ° and 90 °). Further, the arrangement pitch P of each prism is, for example, about 8 μm, and the height t is, for example, about 2 μm. As shown in FIG. 3, the prism array 53 is formed in a slit shape when viewed from above. The prism array 53 can be obtained by molding a resin material having excellent heat resistance and adhesion, for example. Details of the method of forming the prism array 53 will be described later.

  The first alignment film 54 is provided on one surface side of the first substrate 51 so as to cover the first electrode 52 and the prism array 53. The second alignment film 57 is provided on one surface side of the second substrate 55 so as to cover the second electrode 56. In the present embodiment, the first alignment film 54 and the second alignment film 57 regulate the alignment state of the liquid crystal molecules 58 in the initial state (when no voltage is applied) to the horizontal alignment state (horizontal alignment film). Is used. The first alignment film 54 and the second alignment film 57 are subjected to predetermined surface treatment (rubbing treatment, photo-alignment treatment, etc.).

  The liquid crystal layer 58 is provided between one surface of the first substrate 51 and one surface of the second substrate 55. In the present embodiment, the liquid crystal layer 58 is configured using a nematic liquid crystal material having a positive dielectric anisotropy Δε (Δε> 0). The bold lines shown in the liquid crystal layer 58 schematically show the liquid crystal molecules in the liquid crystal layer 58. The liquid crystal molecules when no voltage is applied are aligned substantially horizontally with a predetermined pretilt angle with respect to the substrate surfaces of the first substrate 51 and the second substrate 55.

  Here, the operation of the optical element 5 will be described in detail. When a voltage is applied to the liquid crystal layer 58 via the first electrode 52 and the second electrode 56 of the optical element 5, the arrangement of the liquid crystal molecules in the liquid crystal layer 58 changes, whereby the refractive index value of the liquid crystal layer 58 changes. For this reason, the refraction angle of the light transmitted through the interface between the prism array 53 and the liquid crystal layer 58 which are a plurality of minute inclined projection shapes changes (Snell's law). Although the size of the refraction angle cannot be generally specified depending on the shape of the prism array 53 and the value of the refractive index anisotropy of the liquid crystal layer 58, a refraction angle up to about 18 ° can be realized by adjusting various conditions. It has been confirmed that it can be. This refraction angle can be changed according to the voltage applied to the optical element 5.

  FIG. 4 is a diagram for explaining the relationship between the polarization direction of the light emitted from the liquid crystal display panel 1 and the direction of the alignment treatment in the optical element 5. As shown in the figure, in the liquid crystal display panel 1 of the present embodiment, the output side polarizing plate has a transmission axis in the direction of 45 ° obliquely, and the outgoing light that has passed through the output side polarizing plate is polarized in the direction a1. Yes. In the illustrated example, the outgoing light is polarized in a 45 ° direction with respect to the horizontal direction of the liquid crystal display panel 1. On the other hand, the first substrate 51 is arranged so that the direction a2 of the alignment treatment applied to the first alignment film 54 is substantially parallel to the polarization direction a1 of the emitted light. In the illustrated example, the orientation processing direction a <b> 2 is set to approximately 45 ° with respect to the longitudinal direction (extending direction) a <b> 3 of each prism of the prism array 53. In addition, the second substrate 55 is arranged so that the alignment process direction a4 applied to the second alignment film 57 has an antiparallel relationship with the alignment process direction a2 of the first substrate 51 described above. Yes.

  Here, an advantage of making the direction a2 of the alignment treatment of the first substrate 51 substantially parallel to the polarization direction a1 of the emitted light of the liquid crystal display panel 1 will be described. Normally, the liquid crystal molecules of the liquid crystal layer 58 have an elongated shape, and polarized light in a certain direction (long axis direction of the liquid crystal molecules) can be bent, but polarized light in a certain direction is transmitted as it is. Accordingly, the polarization direction a1 of the light emitted from the liquid crystal display panel 1 and the alignment treatment direction a2 applied to the first substrate 51 disposed on the liquid crystal display panel 1 side in the optical element 5 are arranged in parallel. By doing so, in principle, all components of the emitted light can be bent. That is, the light utilization efficiency is increased. On the other hand, in the case where the polarization direction a1 of the emitted light from the liquid crystal display panel 1 and the alignment treatment direction a2 in the optical element 5 are arranged to be 45 °, for example, in principle, about a part of the emitted light. The half component is bent, but the remaining components cannot be controlled. Further, when the polarization direction a1 and the alignment treatment direction a2 are arranged so as to be orthogonal to each other, in principle, the light emitted from the liquid crystal display panel 1 cannot be controlled by the optical element 5. Therefore, it can be said that it is more desirable to arrange so that the polarization direction a1 of the emitted light from the liquid crystal display panel 1 and the alignment treatment direction a2 in the optical element 5 are substantially parallel. The longitudinal direction a3 of each prism of the prism array 53 is set to a direction in which the entire display image is moved to the left and right relative to the user 200.

  Next, the operation of the image display system 100 of this embodiment will be described with reference to FIG.

  First, the operation state illustrated in FIG. Light incident on the light guide plate 31 from the LED light source 32 is directed obliquely by the light guide plate 31. This obliquely directed light can be tilted in the normal direction (or slightly oblique direction) while maintaining the directivity by the hologram diffusion plate 33. At this time, a relatively high voltage is applied to the optical element 5 to bring the liquid crystal layer 58 of the optical element 5 into a vertically aligned state. Thereby, the light emitted from the backlight 3 and passed through the liquid crystal display panel 1 can be passed in the traveling direction as it is. By making the passing light at this time visible to the left eye of the user 200, the left-eye image can be viewed only by the left eye of the user 200. Control is easier if the passing light at this time is emitted in a slightly inclined state.

  Next, the operation state illustrated in FIG. 5B will be described. In the same manner as in FIG. 5A, light is incident on the liquid crystal display panel 1 from the backlight 3. At this time, a relatively low voltage (0 V in this example) is applied to the optical element 5 to bring the liquid crystal layer 58 of the optical element 5 into a horizontal alignment state. Thereby, the light emitted from the backlight 3 and passed through the liquid crystal display panel 1 can be refracted by the optical element 5 and its traveling direction can be changed. By making the passing light at this time visible to the right eye of the user 200, the right eye image can be viewed only by the right eye of the user 200.

  By performing the operation of changing the direction of the light emitted from the liquid crystal display panel 1 with the optical element 5 at a high speed as described above, a stereoscopic image can be visually recognized by the user 200. At this time, the switching cycle between the right-eye image and the left-eye image displayed on the liquid crystal display panel 1 is, for example, 120 Hz or 240 Hz. Here, for example, assuming that the switching cycle is 120 Hz, the image for the right eye and the image for the left eye are alternately displayed every about 8.3 milliseconds. For example, in the frame in which the image for the left eye is displayed, the optical element driving unit 6 applies a relatively high voltage (for example, 30 V) to the optical element 5. As a result, the liquid crystal layer 58 of the optical element 5 changes to the vertical alignment state as described above, and the light emitted from the liquid crystal display panel 1 passes through the optical element 5 without being bent in the traveling direction. Only the left eye of the user 200 can visually recognize the left eye image (see FIG. 5A). Next, in the frame in which the image for the right eye is displayed, the optical element driving unit 6 applies a relatively low voltage (for example, 0 V) to the optical element 5. As a result, the liquid crystal layer 58 of the optical element 5 changes to the horizontal alignment state as described above, and the emitted light from the liquid crystal display panel 1 is bent in the traveling direction by the optical element 5 and passes as described above. The right-eye image can be visually recognized only by the right eye of the person 200 (see FIG. 5B).

  Although the response time of the optical element 5 depends on various conditions and cannot be generally stated, a relatively high voltage of 35 V is applied to the optical element 5 manufactured according to the above-described example conditions. When 0V is applied as a low voltage, the response time at the rise is 1.6 to 1.7 milliseconds, the response time at the fall is 2.8 to 4.2 milliseconds (both at room temperature) Yes, the response speed is necessary and sufficient when a switching cycle of 120 Hz is assumed. Also, the time ton from when a high voltage is applied until the amount of change in the light angle (traveling direction) reaches 90% of the maximum amount of change, and the amount of change in the angle of light after the low voltage is applied is the maximum amount of change. It can be seen that the time toff until 10% of the ton is 0.8 to 0.9 milliseconds for ton and 1.7 to 2.9 milliseconds for ton, and the substantial change time is very fast. . Regarding the correlation with the alignment treatment method, the response time tends to be slightly shorter when the photo-alignment treatment is used, but this is not a significant difference.

  Next, an example of a method for manufacturing the optical element 5 will be described in detail.

  First, glass substrates for use as the first substrate 51 and the second substrate 55 are prepared. As these glass substrates, those having a conductive film made of a transparent conductive material such as ITO (indium tin oxide) in advance are more preferable. For example, a pair of glass substrates having an ITO film with a thickness of 1500 mm, a plate thickness of 0.7 mm, and a glass material made of non-alkali glass are prepared. About each of the 1st board | substrate 51 and the 2nd board | substrate 55, the 1st electrode 52 and the 2nd electrode 56 are formed by patterning an ITO film | membrane suitably.

  Next, the prism array 53 is formed on the first electrode 52 of the first substrate 51. Here, the cross section is triangular, the pitch P is 8 μm, the height t is about 2 μm, the apex angle is 75 °, the base angles are 15 ° and 90 °, and a mold having a slit shape is seen from above. The prism array 53 is formed by using this.

  Specifically, a photocurable resin material is dropped onto the first substrate 51, a mold is placed thereon, and pressing is performed in a state where the back side of the first substrate 51 is reinforced with a thick quartz substrate or the like. . After being pressed for a certain period of time (for example, 1 minute or longer), the photocurable resin material is sufficiently spread, and then the photocurable resin material is cured by irradiating light from the first substrate 51 side. The amount of light irradiation is appropriately set to a value sufficient to cure the photocurable resin material. Here, in general, the prism material has low heat resistance, and the characteristics are often deteriorated by heat treatment (for example, 180 ° C. or more) when the first alignment film 54 is formed on the prism array 53. On the other hand, in this embodiment, a photo-curing (for example, UV-curing) acrylic resin material that hardly causes a decrease in transmittance characteristics before and after the heat treatment is used. The refractive index of the photocurable resin material is, for example, about 1.51.

  Thus, the prism array 53 made of the transparent resin film is formed on the first substrate 51. Thereafter, the first substrate 51 on which the prism array 53 is formed is cleaned by a cleaning machine. The cleaning can be performed, for example, in the order of brush cleaning using an alkaline detergent, pure water cleaning, air blow, ultraviolet (UV) irradiation, and infrared (IR) drying, but is not limited thereto. High pressure spray cleaning or plasma cleaning may be performed.

  Next, a first alignment film 54 is formed on the first substrate 51 on which the prism array 53 is formed. Similarly, a second alignment film 57 is formed on the second substrate 55. Here, for example, polyimide is used as the alignment film. An appropriate film is formed on the first substrate 51 and the second substrate 55 by an appropriate method such as a flexographic printing method, an inkjet method, a spin coating method, a slit coating method, or a combination of a slit method and a spin coating method. The film is applied in a thickness (for example, about 800 mm) and heat treatment (for example, baking at 180 ° C. for 1.5 hours) is performed. Then, an alignment process is performed on each of the first alignment film 54 and the second alignment film 57 obtained by the heat treatment. This alignment process is performed so that the alignment direction of the liquid crystal molecules on each substrate is antiparallel when the first substrate 51 and the second substrate 55 are overlapped. The alignment process is performed so that the direction of the alignment process on the first alignment film 54 is 45 ° with respect to the extending direction of each prism of the prism array 53.

  Here, for example, a rubbing process is performed as the alignment process, but an alignment process such as a photo-alignment process may be used, or a plurality of types of alignment processes may be combined. For example, a combination of performing a photo-alignment process on the first substrate 51 and performing a rubbing process on the second substrate 55 is conceivable. When performing the photo-alignment treatment on the first substrate 51, for example, a method of irradiating the first substrate 51 with light polarized with ultraviolet rays from the normal direction can be used. At this time, the ultraviolet rays are radiated from the vertical direction to the first substrate 51, but are radiated from the direction inclined relatively by 45 ° to the slope portions of the prisms of the prism array 53. Will be equal. The wavelength of the polarizing filter used for exposure is, for example, 310 nm.

  Next, a main sealant containing an appropriate amount (for example, 2 to 5 wt%) of a gap control agent is formed on one substrate (for example, the first substrate 51). The main sealant is formed by screen printing or a dispenser, for example. The diameter of the gap control agent can be selected so that the thickness of the liquid crystal layer 58 including the base layer of the prism array 53 and the height of the prism is as thin as about 2 to 4 μm. In this embodiment, a plastic ball having a diameter of 10.5 μm is used as the gap control agent. A gap control agent is sprayed on the other substrate (for example, the second substrate 55). For example, in this embodiment, 3.5 μm plastic balls are sprayed by a dry gap spreader.

  Next, the first substrate 51 and the second substrate 55 are overlaid, and the main sealant is cured by heat treatment in a state where pressure is constantly applied by a press machine or the like. Here, for example, heat treatment is performed at 150 ° C. for 3 hours. Thereafter, a liquid crystal layer 58 is formed by filling a gap between the first substrate 51 and the second substrate 55 with a liquid crystal material. The liquid crystal material is filled by, for example, a vacuum injection method. In this embodiment, a liquid crystal material having a positive dielectric anisotropy Δε and a relatively low viscosity is used. The refractive index anisotropy of the liquid crystal material is a value suitable for the purpose because it relates to the angle at which light is bent. After the liquid crystal material is injected, an end sealant is applied to the inlet and sealed. Then, the alignment state of the liquid crystal molecules of the liquid crystal layer 58 is adjusted by appropriately performing a heat treatment (for example, at 120 ° C. for 1 hour) after sealing. The optical element 5 of this embodiment is obtained as described above.

FIG. 6 is a schematic cross-sectional view showing another structural example of the optical element. The optical element 5a shown in FIG. 6 includes a first substrate 51, a first electrode 52a, a prism array 53a, a first alignment film 54a, a second substrate 55, a second electrode 56, a second alignment film 57, and a liquid crystal layer 58. Consists of. In the optical element 5 shown in FIG. 2 described above, the prism array 53 is arranged above the first electrode 52. However, in the optical element 5a shown in FIG. 6, the first electrode 52a is arranged on the prism array 53a. This is a structural difference. If it is on the prism array 53a formed using a resin material having high heat resistance as described above, the first electrode 52a made of a transparent conductive material such as ITO is provided on the prism array 53a as in this example. You can also. Although not shown, it is also preferable that a silicon oxide (SiO ₂ ) film is provided between the prism array 53a and the first electrode 52a in order to further improve the adhesion between them. In the optical element 5 a illustrated in FIG. 6, the prism array 53 a does not exist between the first electrode 52 a on the first substrate 51 and the liquid crystal layer 58, and the liquid crystal layer 58 is directly connected from the first electrode 52 a. Since a voltage can be applied, the voltage for driving the optical element 5a can be further reduced. Further, in both the optical element 5 shown in FIG. 2 and the optical element 5a shown in FIG. 6, one or both of the first electrode and the second electrode are patterned into a stripe shape (strip shape) or the like. Also good. Thereby, it is possible to set a region where the viewing angle direction of the display image is changed and a region where the viewing angle direction is not changed.

  FIG. 7 is a schematic sectional view showing another structural example of the prism array. In the prism array 53b shown in FIG. 7A, the inclination angles of the prisms are different along the arrangement direction of the plurality of prisms (vertical direction in the drawing). Specifically, in the illustrated example, the inclination angle becomes larger as the prisms are arranged in the downward direction in the figure. The same applies to the prism array 53c shown in FIG. The prism array 53b shown in FIG. 7A has the same base length and different heights, but the prism array 53c shown in FIG. The height is the same, and the length of the base of each prism is different. By gradually changing the inclination angle of each prism in the prism array as described above, the refraction angle of light in the optical element can be gradually increased (or decreased). Therefore, even when the size of the liquid crystal display panel 1 is relatively large, it is possible to improve the visibility of the image for the user. Specifically, assuming the arrangement shown in FIG. 5 described above, in order for the right-eye image to enter the right eye of the user 200, it is necessary to bend the light more toward the lower side in the figure. In such a situation, the prism array 53b or the prism array 53c is more preferable.

  In addition, the prism array 53c is more preferable from the viewpoint that the distance between the first substrate and the second substrate is thinner and more easily obtained. In the case of the prism array 53b, in order to keep the substrate interval uniform, the prism shape and the substrate interval are set so that the height difference of each prism in the prism array is within the elastic deformation range allowed by the gap control agent. It is preferable to do. In this case, it is preferable to anticipate deformation of less than about 10%. When the above-mentioned prism having a height of 2 μm has the maximum prism height, this condition is satisfied by making the substrate interval larger than 20 μm. At this time, the gap between the substrates is mainly held by the gap control agent in the main seal, and it is also preferable to make the amount of the gap control agent sprayed on the substrate very small. Further, the substrate may be configured without spraying the gap control agent.

  In addition, this invention is not limited to the content of each embodiment mentioned above, In the range of the summary of this invention, it can change and implement variously.

  For example, in the above-described embodiment, a liquid crystal display device is shown as an example of an image display device, but the present invention is not limited to this. The image display device in the present invention may be any device as long as the emitted light is polarized, and for example, an organic EL (electroluminescence) display device having a monochromatic type and not having a mirror appearance can be used.

  Further, although the liquid crystal layer in the above-described embodiment is restricted to the horizontal alignment, it may be an alignment mode such as 90 ° twist alignment. Further, the alignment direction of the liquid crystal molecules may be changed by adding a chiral agent to the liquid crystal layer. Further, the method for forming the liquid crystal layer is not limited to vacuum injection, and an ODF method may be used.

  Further, the cross-sectional shape of the prism array is not limited to the triangular shape described above. The cross-sectional shape may be, for example, a sine wave (sine curve). Further, the upper surface shape of the prism array is not limited to the stripe shape described above. The top surface shape may be, for example, a lattice shape, a concentric circle shape, an ellipse shape, a Fresnel lens shape, or a dot shape. Furthermore, although the longitudinal direction of each prism of the prism array and the direction of the orientation treatment are set to 45 °, the angle is not limited to this and can be set as appropriate.

  In the above-described embodiment, the optical element is arranged on the front side of the image display device. However, the optical element may be arranged on the rear side of the image display device. However, it can be said that it is more preferable to dispose the optical element on the front side in terms of controllability of viewing angle characteristics.

  In addition, in the image display system of the above-described embodiment, when normal two-dimensional image display is performed without performing stereoscopic image display, it is basically unnecessary to drive the optical element. The optical element may be driven in synchronization with a switching cycle (for example, 60 Hz) or in a cycle faster than the switching cycle. Thereby, the viewing angle can be perceived more broadly for the user viewing the normal image. The image display system of the present embodiment can also realize such an operation, which is also one of the preferable operation modes.

1: Liquid crystal display panel (LCD)
2: liquid crystal drive unit 3: backlight 5, 5a: optical element 6: optical element drive unit 51: first substrate 52, 52a: first electrode 53, 53a: prism array 54, 54a: first alignment film 55: first Two substrates 56: Second electrode 57: Second alignment film 58: Liquid crystal layer 100: Image display system 200: User

Claims (6)

An image control device used in combination with an image display device that alternately displays a first image and a second image,
An optical element;
An optical element driving unit that drives the optical element in response to a switching timing of the first image and the second image by the image display device;
The optical element is
A first substrate and a second substrate disposed opposite to each other;
A first electrode provided on the first substrate and connected to the optical element driving unit;
A prism array having a plurality of prisms provided on the first substrate;
A first alignment film provided above the first electrode and the prism array;
A second electrode provided on the second substrate and connected to the optical element driving unit;
A second alignment film provided on the upper side of the second electrode;
A liquid crystal layer provided between the first alignment film of the first substrate and the second alignment film of the second substrate;
Image control device.   The optical element driving unit supplies a relatively high voltage to the optical element when the first image is displayed, and supplies a relatively low voltage to the optical element when the second image is displayed. Item 2. The image control apparatus according to Item 1.   The image control device according to claim 1, wherein the optical element is disposed on a front side of the image display device.   The image control device according to claim 1, wherein the image display device is a liquid crystal display device having a directional backlight.   The image control apparatus according to claim 1, wherein the prism array has different inclination angles of the prisms along an arrangement direction of the plurality of prisms. The image control apparatus according to any one of claims 1 to 5,
An image display device for alternately displaying the first image and the second image;
An image display system comprising:

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