JP5587272B2 - Image display device - Google Patents

Description

  The present invention relates to an image display device.

  The liquid crystal has fluidity like a liquid, has anisotropy in electro-optical characteristics, and can control various molecular orientation states. There is known a liquid crystal lens in which a liquid crystal having such properties is sealed between a pair of substrates, and a refractive index distribution characteristic is controlled by controlling a voltage applied to a liquid crystal layer. Patent Documents 1 and 2 disclose image display devices in which liquid crystal lenses are arranged on the viewer side (front surface, display surface side) of the display panel. For example, the image display disclosed in Patent Document 1 is disclosed. The device is a three-dimensional display device that provides a stereoscopic view to an observer.

  Here, FIG. 7A and FIG. 7B are diagrams for explaining an image display device in which a liquid crystal lens is arranged on the front surface of the liquid crystal display panel PNL.

  First, in FIG. 7A, no voltage is applied to the liquid crystal layer LC, and the alignment of the liquid crystal molecules is in the initial alignment state (here, parallel to the main surface of the first substrate B1 and the main surface of the second substrate B2). Direction). For this reason, in FIG. 7A, the liquid crystal lens is in a state where it does not exhibit the lens effect. On the other hand, in FIG. 7B, a voltage is applied to the liquid crystal layer LC, and the alignment state of the liquid crystal molecules is changed by the electric field from the electrode formed on the substrate, so that the liquid crystal lens has a lens effect. Light emitted from each pixel of the panel PNL changes the traveling direction. Therefore, in the case of FIG. 7A and the case of FIG. 7B, different images (for example, a two-dimensional image and a three-dimensional image) are provided to an observer at a predetermined position observing the image display device.

JP-A-7-72445 Special table 2009-51942 gazette

  As one of the display panels disposed on the back surface of the liquid crystal lens, it is conceivable to use a liquid crystal display panel.

FIG. 8 is a diagram for explaining a relationship between incident light and outgoing light to the liquid crystal lens and liquid crystal molecules LM in the liquid crystal lens. The left side of FIG. 8 shows the case of incident light having a polarization direction parallel to the molecular long axis of the liquid crystal molecule, and the right side of FIG. 8 shows a predetermined angle with respect to the molecular long axis direction DLM of the liquid crystal molecule. This shows the case of incident light having polarized light in a direction inclined by θ ₀ . When the left and right states shown in FIG. 8 are compared, the amount of emitted light is larger in the left state than in the right state.

  For this reason, when the liquid crystal display panel is disposed on the back surface of the liquid crystal lens, the amount of transmitted light can be increased by aligning the direction of the transmission axis of the upper polarizing plate with the initial alignment direction of the liquid crystal lens. Conceivable.

  Next, FIG. 9 is a diagram for explaining an example of the configuration of an image display device including a liquid crystal display panel PNL and a liquid crystal lens LZ, and FIG. 10A is a diagram for explaining an electrode structure of the liquid crystal lens LZ in FIG. is there.

  As shown in FIG. 9, the liquid crystal display panel PNL includes a lower polarizer PL1, a liquid crystal cell LS, and an upper polarizer PL2, and the transmission axes of the lower polarizer PL1 and the upper polarizer PL2 are orthogonal to each other. It is supposed to be. Further, as shown in FIG. 10A, the liquid crystal lens LZ has an electrode structure in which a plurality of line-shaped electrodes E1 are formed on one substrate of the liquid crystal lens LZ, and a plate-like electrode E2 is formed on the other substrate. The

  Here, the alignment direction RB of the liquid crystal lens LZ is set in a direction perpendicular to the plurality of line-shaped electrodes E1, and the alignment direction RB is parallel to the transmission axis of the upper polarizing plate PL2. In such a direction, the amount of transmitted light is increased.

  However, in the case of the liquid crystal lens LZ as shown in FIGS. 9 and 10A, when an electric field is applied to the liquid crystal layer of the liquid crystal lens LZ, as shown in FIG. 10B, which is an enlarged view of the broken line frame XB in FIG. 10A. A jagged (zigzag) disclination DS1 results. Here, the disclination DS1 is a region in which liquid crystal molecules are arranged in a direction perpendicular to the main surface of the substrate on the line-shaped electrode E1. The occurrence of such a jagged (zigzag) disclination DS1 leads to degradation of the image quality of the image display device. In the display of a three-dimensional image, the right eye image and the left eye image are displayed in each eye of the observer. Crosstalk occurs due to the mixed images. In particular, crosstalk becomes prominent at the bent portion of the jagged (zigzag) disclination DS1, and this crosstalk (that is, a mixture of images) is visually recognized as a bright spot.

  An object of the present invention is to suppress the occurrence of disclination as described above, particularly the occurrence of jagged (zigzag) disclination, in an image display device having a liquid crystal lens on the viewer side of a liquid crystal display panel. And

  In view of the above object, an image display device according to the present invention is an image display device having a liquid crystal display panel including a plurality of pixels, and a liquid crystal lens disposed on one side of the liquid crystal display panel. The liquid crystal lens includes a first substrate, a second substrate facing the first substrate, a liquid crystal layer sandwiched between the first substrate and the second substrate, and the first substrate A plurality of electrodes formed in at least one of the substrate and the second substrate and extending in the first direction, and an alignment film is provided on the liquid crystal layer side of the one substrate The liquid crystal display panel is provided with a polarizing plate having a transmission axis in a direction substantially perpendicular to the first direction on a side where the liquid crystal lens is disposed, and the liquid crystal layer of the alignment film The orientation direction is different from the direction perpendicular to the first direction. The second direction, and wherein the.

  In the image display device according to the aspect of the invention, the plurality of pixels of the liquid crystal display panel may have a multi-domain pixel structure. Furthermore, the angle formed by the first direction and the direction of the transmission axis of the polarizing plate may be within a range of 90 ° ± 0.5 °.

  In the image display device according to the aspect of the invention, the direction perpendicular to the first direction and the second direction may form an angle of 1 ° to 12 °.

  According to the present invention, the occurrence of disclination as described above can be suppressed in an image display device including a liquid crystal lens on the viewer side of the liquid crystal display panel.

1 is a diagram schematically showing an image display device according to a first embodiment of the present invention. It is a figure which shows schematically the electrode structure of the liquid crystal lens of 1st Embodiment. It is a figure which shows schematically the mode of the III-III cross section in FIG. FIG. 4 is an enlarged view of a broken-line frame IV in FIG. 2 and shows a state of disclination that occurs when an electric field is applied to a liquid crystal lens. It is a figure which shows a mode that the liquid crystal molecule in the liquid crystal lens right above a line-shaped electrode is rotated by an electric field. It is a figure which shows the initial alignment direction prescribed | regulated by alignment film, and the direction which a liquid crystal molecule rotates when an electric field is applied. It is a figure explaining the display principle of the image display apparatus which has a liquid crystal lens. It is a figure explaining the display principle of the image display apparatus which has a liquid crystal lens. It is a figure explaining the relationship between the incident light and emitted light to a liquid crystal lens, and the liquid crystal molecule in a liquid crystal lens. It is a figure explaining an example of the image display apparatus provided with the liquid crystal display panel and the liquid crystal lens. It is a figure explaining the electrode structure of the liquid crystal lens LZ in FIG. FIG. 10B is an enlarged view of a broken line frame XB in FIG. 10A, showing a zigzag disclination that occurs when an electric field is applied to the liquid crystal lens.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First embodiment]
FIG. 1 is a schematic diagram of an image display device DP according to the first embodiment of the present invention. The image display device DP includes a liquid crystal display panel PNL, a liquid crystal lens LZ disposed on the viewer side of the liquid crystal display panel PNL, and a backlight BL disposed on the back surface of the liquid crystal display panel PNL.

  The liquid crystal lens LZ includes a first substrate B1, a second substrate B2, and a liquid crystal layer LC sandwiched between them. The liquid crystal lens LZ of the present embodiment provides a two-dimensional image to the observer when no electric field is applied to the liquid crystal layer LC, and forms a lens array when the electric field is applied to the liquid crystal layer LC. Provide a three-dimensional image.

  The liquid crystal display panel PNL includes a liquid crystal cell LS, a lower polarizing plate PL1 disposed on the backlight BL side, and an upper polarizing plate PL2 disposed on the liquid crystal lens LZ side. The liquid crystal display panel PNL has a display area having a plurality of pixels arranged in a matrix.

  The image display apparatus according to the present embodiment has a function of switching between two-dimensional display and three-dimensional display. For this reason, the plurality of pixels in the display region of the liquid crystal display panel PNL are specifically divided into a plurality of pixel groups including two or more pixels, and the pixel groups are divided into three-dimensional displays. It has a pixel that outputs a display for the right eye and a pixel that outputs a display for the left eye. Further, the liquid crystal lens LZ is configured so that the orientation of the liquid crystal molecules of the liquid crystal layer LC is controlled by applying an electric field, and a lens array having a plurality of cylindrical lens portions is formed. The portion corresponds to each pixel group. Each lens portion outputs an image for the right eye to the right eye of the observer at a predetermined position, and outputs an image for the left eye to the left eye of the observer, and extends in the vertical direction as viewed from the observer. It has become a thing.

  In addition, the liquid crystal display panel PNL of the present embodiment is in a horizontal electric field driving method (In Plane Switching), and each pixel in the liquid crystal display panel PNL has a multi-domain pixel structure in order to widen the viewing angle. ing. Specifically, each pixel is formed with a comb-like pixel electrode and a flat counter electrode, and the comb-like pixel electrode is based on the rubbing direction (alignment direction) of the alignment film of the liquid crystal cell LS. As a portion extending in a direction inclined by a predetermined angle α and a portion extending in a direction inclined by −α. Thus, each pixel in the liquid crystal display panel PNL is formed with two regions having different rotation directions of liquid crystal molecules when an electric field is applied, and the liquid crystal display panel PNL is a multi-domain panel.

  FIG. 2 is a diagram illustrating a planar configuration of the plurality of electrodes E1 formed on the first substrate B1 of the liquid crystal lens LZ. 3 and 4 show the state when an electric field is applied to the liquid crystal lens LZ. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2, and FIG. It is an enlarged view showing a region.

  First, as shown in FIG. 2, the plurality of electrodes E1 on the first substrate B1 are formed so as to extend in the first direction, and are parallel to each other at a predetermined interval. As seen from the observer of the display device, it is line-shaped in the vertical direction. Further, the electrode E2 formed on the second substrate B2 is formed in a flat plate shape, and as shown in FIG. 3, the electrodes on the plurality of electrodes E1 on the first substrate B1 and on the second substrate B2 An alignment film OR is formed on E2. The two alignment films OR define the alignment direction of liquid crystal molecules (also referred to as an initial alignment direction in this specification) when no electric field is applied to the liquid crystal layer LC. Between the two electrodes E1 shown in FIG. 3, a pixel that outputs a display for the right eye and a pixel that outputs a display for the left eye in a three-dimensional display are arranged in pairs. In FIG. 3, a pair of pixels PX including three sub-pixels are schematically shown.

  Next, as shown in FIG. 2, the initial alignment direction RB of the liquid crystal lens LZ in the present embodiment is a first tilted angle θ with respect to a direction perpendicular to the first direction in which the plurality of electrodes E1 extend. 2 direction is set. When no electric field is applied between the electrode E1 and the electrode E2, the liquid crystal molecules in the liquid crystal layer LC are aligned on the main surface of the first substrate B1 by the two alignment films OR that are both aligned in the second direction. Parallel to and in the second direction.

  Then, when an electric field is applied to the liquid crystal layer LC, as shown in FIG. 3, a convex lens-shaped lens interface UL is formed by the change in orientation of the liquid crystal molecules, that is, between the two lens interfaces UL to be formed, that is, a line A disclination DS2 as shown in FIG. 4 is formed in a region that overlaps the planar electrode E1 in a plan view. As will be described later, the initial alignment direction by the alignment film OR of the liquid crystal lens LZ is set in a second direction shifted by an angle θ from the direction perpendicular to the extending direction of the line-shaped electrode E1. Thus, the generation of the jagged disclination DS1 as shown in FIG. 10B is suppressed, and a linear disclination DS2 as shown in FIG. 4 is obtained. The angle θ is a included angle formed by the initial alignment direction RB and a direction perpendicular to the first direction (that is, a substantially short side direction of the line-shaped electrode E1), and an angle of 15 degrees or less, Specifically, it is desirable to set the angle to 1 degree or more and 12 degrees or less, and it is more preferable to set the angle to 3 degrees or more and 10 degrees or less. The initial alignment direction RB may be shifted to the clockwise side when viewed from the observer side with respect to the direction perpendicular to the first direction, or may be shifted to the counterclockwise side. .

  The liquid crystal display panel PNL of the present embodiment is a multi-domain type display panel, and is a comb-like electrode (when the comb-like electrode is a pixel electrode, when it is a counter electrode, both electrodes may be the same). Two portions having different extending directions are formed. In general, in the case of a multi-domain liquid crystal display panel, the rubbing direction (alignment direction) of the alignment film is set to a direction that is an axis of symmetry with respect to the two portions. The rubbing direction and the transmission axis of the upper polarizing plate PL2 are set in the horizontal direction or the vertical direction as viewed from the observer. In the present embodiment, the rubbing direction of the liquid crystal cell LS is set to the horizontal direction when viewed from the observer, and the transmission axis of the upper polarizing plate PL2 is the first direction (the vertical direction in which the line-shaped electrode E1 extends). Is set in a direction substantially perpendicular to the direction. Further, the term “substantially vertical” as used herein includes a range of manufacturing errors in addition to the case of being completely vertical, specifically, a range within 90 ° ± 0.5 °.

  As described above, the image display device of the present embodiment employs a multi-domain liquid crystal display panel, and the transmission axis of the upper polarizing plate PL2 is in the horizontal direction, but the initial alignment direction of the liquid crystal lens LZ is the upper polarization. The angle θ is shifted with respect to the transmission axis direction of the plate PL2. For this reason, although the amount of transmitted light from the liquid crystal lens LZ is slightly reduced, the initial alignment direction of the liquid crystal lens LZ is set so as to be deliberately shifted from the direction perpendicular to the extending direction of the line-shaped electrode E1. As a result, the generation of the jagged (zigzag) disclination DS1 as shown in FIG. 10B is suppressed, thereby preventing the deterioration of the image quality during three-dimensional display.

  Hereinafter, the disclination occurring between the lens portions of the cylindrical lens shape will be described in more detail with reference to FIGS.

  FIG. 5 is a diagram illustrating a state in which the liquid crystal molecules directly above the line-shaped electrode E1 are rotated by an electric field. The state of rotation of the liquid crystal molecules between two lens portions formed by the application of the electric field is illustrated. It is shown. As shown in the figure, on the upper side of the electrode E1, the electric field F was applied perpendicularly to the first substrate B1, and the liquid crystal molecules on the upper side of the electrode E1 were aligned in the in-plane direction by the electric field F. The molecular long axis rotates and rises, and the direction of the molecular long axis becomes perpendicular to the first substrate B1.

  FIG. 6 is a diagram illustrating the initial alignment direction RB defined by the alignment film OR and the rotation direction of the liquid crystal molecules. The left side of FIG. 6 is a case where the initial alignment direction RB exists in a direction perpendicular to the line-shaped electrode E1, and the right side of FIG. 6 is a direction perpendicular to the extending direction of the line-shaped electrode E1. The case where the initial alignment direction RB exists in the direction rotated by the angle θ with respect to FIG.

  When the liquid crystal molecules on the upper side of the electrode E1 rise in the direction perpendicular to the main surface of the first substrate B1 by the electric field F, the major axis of the liquid crystal molecules rises with a certain degree of rotation when viewed in plan, as shown in FIG. . In the case of the left side of FIG. 6, the rotation direction of the liquid crystal molecules is not regulated in either the clockwise direction or the counterclockwise direction, and variations occur in the rising direction of the liquid crystal molecules. The jagged (zigzag) disclination DS1 in FIG. 10B is considered to be caused by variations in the rising direction. Due to the variation in the rising direction, there is a shift in the force that causes the liquid crystal molecules to behave to form a liquid crystal lens on one side and the other side of the electrode E1. Due to this deviation in force, the region where the liquid crystal molecules rise on the electrode E1 is not formed linearly (that is, formed along the extending direction of the electrode E1), but is formed in a zigzag shape.

  On the other hand, in the case of the right side of FIG. 6, since the rotation direction of the liquid crystal molecules is regulated in the counterclockwise direction, variation in the rising direction that causes the disclination to occur in a zigzag shape is suppressed, As shown in FIG. 4, the disclination DS2 is formed in a line along the electrode E1. By forming the disclination DS2 in a straight line, the occurrence of local distortion of the cylindrical lens-like lens portion formed between the two electrodes E1 is suppressed, and the deterioration of the image quality is prevented. Further, crosstalk caused by jagged (zigzag) disclination can be prevented, and the image quality can be improved.

  In the liquid crystal display panel PNL and the liquid crystal lens LZ of the present embodiment, the alignment film may be a photo alignment film or an alignment film formed by rubbing. In this embodiment, the liquid crystal display panel PNL is an IPS type, but another VA type or TN type liquid crystal display panel may be used.

  In the present embodiment, the line-shaped electrode E1 is formed on the first substrate B1 of the liquid crystal lens LZ. However, for example, a plurality of line-shaped electrodes may be formed on the second substrate B2. Any electrode shape may be used as long as a cylindrical lens array is formed on the liquid crystal lens LZ.

  The present invention is not limited to the above-described embodiments, and various modifications can be made. For example, the configuration described in each embodiment can be replaced with a configuration that is substantially the same, a configuration that exhibits the same effect, or a configuration that can achieve the same purpose.

  DP image display device, LZ liquid crystal lens, LC liquid crystal layer, B1 first substrate, B2 second substrate, PNL liquid crystal display panel, PL1 lower polarizing plate, PL2 upper polarizing plate, LS liquid crystal cell, OR alignment film, DS1, DS2 Disclination, LM liquid crystal molecule, RB initial alignment direction, UL lens interface.

Claims (3)

An image display device comprising: a liquid crystal display panel having a plurality of pixels; and a liquid crystal lens disposed on one side of the liquid crystal display panel,
The liquid crystal lens is
A first substrate and a second substrate facing the first substrate;
A liquid crystal layer sandwiched between the first substrate and the second substrate;
A plurality of electrodes formed on at least one of the first substrate and the second substrate and extending in a first direction;
An alignment film is formed on the liquid crystal layer side of the one substrate,
The liquid crystal display panel includes a polarizing plate having a transmission axis in a direction substantially perpendicular to the first direction on a side where the liquid crystal lens is disposed.
The alignment direction of the alignment film, Ri second direction der constituting a direction a predetermined angle which is perpendicular to the first direction,
The predetermined angle is an angle of 1 ° to 15 °,
When an electric field is applied between the first substrate and the second substrate, the rotation direction of the liquid crystal molecules contained in the liquid crystal layer is restricted to either clockwise or counterclockwise when viewed in a plan view. The
An image display device characterized by that.   2. The image display device according to claim 1, wherein the plurality of pixels of the liquid crystal display panel have a multi-domain pixel structure. An image display device according to any one of claims 1 to 2 , wherein
An angle formed by the first direction and the direction of the transmission axis of the polarizing plate is in a range of 90 ° ± 0.5 °.

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