KR20120096194A - Electrically-driven liquid crystal lens and image display device using the same - Google Patents

Abstract

PURPOSE: A liquid crystal electric field lens and an image display device using the same are provided to make an electric field lens to a radially uniform lens profile without directivity. CONSTITUTION: A resistor(115) connects a plurality of first electrodes. A second electrode(121) is formed on a frontal side of a second substrate. A liquid crystal layer(150) is formed between a first substrate and a second substrate. First and second voltage terminals(111,117) are connected to first electrodes in the outermost area and the most center area. The first and second voltage terminals apply different voltages.

Description

Liquid crystal field lens and image display device using the same {Electrically-Driven Liquid Crystal Lens and Image Display Device Using the Same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal field lens, and more particularly, to a liquid crystal field lens having a radially even lens profile without directionality and an image display device using the same.

The services to be realized for the high speed of information to be built on the high-speed information communication network today are 'seeing and listening' multi-media centering on digital terminals that process text, voice, and video at high speed from simply 'listening and talking' service like the current telephone. It is expected to develop into a media type service and ultimately become a hyper-space realistic 3D stereoscopic information communication service that transcends time and space.

In general, the three-dimensional image representing the three-dimensional image is made by the principle of stereo vision through two eyes, because the parallax of two eyes, that is, the two eyes are about 65mm apart, the left and right side due to the difference between the positions of the two eyes The eyes see slightly different images. As such, the difference in the image due to the positional difference between the two eyes is called binocular disparity. The 3D stereoscopic display device uses the binocular parallax to allow the left eye to see only the image of the left eye and the right eye to see only the right eye image.

In other words, the left and right eyes see different two-dimensional images, and when these two images are delivered to the brain through the retina, the brain accurately fuses them to reproduce the depth and reality of the original three-dimensional image. Such a capability is commonly referred to as stereography, and a device in which it is applied as a display device is called a stereoscopic display device.

Meanwhile, the stereoscopic display device may be classified according to components that form a lens that implements 3D (3-dimension). For example, a method of configuring a lens using a liquid crystal layer is called a liquid crystal field lens method.

In general, a liquid crystal display device is composed of two opposite electrodes and a liquid crystal layer formed therebetween. The liquid crystal molecules of the liquid crystal layer are driven by an electric field generated by applying a voltage to the two electrodes. Liquid crystal molecules have polarization properties and optical anisotropy. Here, the polarization property means that when liquid crystal molecules are placed in an electric field, charges in the liquid crystal molecules are attracted to both sides of the liquid crystal molecules so that the molecular arrangement direction is changed according to the electric field, and optical anisotropy is characterized by the elongated structure of the liquid crystal molecules and the aforementioned molecular arrangement direction. This means that the path of the outgoing light or the polarization state is changed differently according to the incident direction or the polarization state of the incident light.

Accordingly, the liquid crystal layer may exhibit a difference in transmittance due to voltages applied to two electrodes, and may display an image by changing the difference for each pixel.

Recently, a liquid crystal lens electrically driven, in which a liquid crystal layer functions as a lens using the characteristics of the liquid crystal molecules, has been proposed.

In other words, the lens is to control the path of the incident light by position using the difference in the refractive index between the material constituting the lens and the air, when the liquid crystal layer is driven by applying a different voltage to each position of the electrode to the liquid crystal layer to form an electric field The incident light incident on the liquid crystal layer feels a different phase change for each position, and as a result, the liquid crystal layer can control the path of the incident light like an actual lens.

Hereinafter, a conventional liquid crystal field lens will be described with reference to the accompanying drawings.

1 is a cross-sectional view illustrating a unit lens cell of a conventional liquid crystal field lens, and FIG. 2 is a perspective view illustrating an optical path profile when a plurality of unit lens cells of FIG. 1 are configured.

As shown in FIG. 1, the conventional liquid crystal field lens includes a first substrate 10 and a second substrate 20 facing each other, and a liquid crystal layer 30 formed between the first and second substrates 10 and 20. do.

Here, the first electrode 11 is formed for each unit lens cell on the first substrate 10. That is, the first electrode 11 may be located at the center of the unit lens cell or at the edge.

In this case, the distance from the center of one side of the first electrode 11 to the center of the other side of the first electrode 11 between the adjacent first electrodes 11 is called a pitch, and the same pattern with the pitch as a cycle (First electrode) is formed repeatedly.

The front second electrode 21 is formed on the second substrate 20 facing the first substrate 10.

The first and second electrodes 11 and 21 are made of a transparent metal. The liquid crystal layer 30 is formed in the spaced space between the first and second electrodes 11 and 21, and the liquid crystal molecules forming the liquid crystal layer 30 cross the first electrode 11. In each lens region L of, as shown in FIG. 2, a parabolic dislocation surface is provided. That is, the liquid crystal molecules of the liquid crystal layer 30 react according to the intensity and distribution of the electric field, and the voltage difference applied to the first electrode 11 and the second electrode 21 and the dielectric anisotropy of the liquid crystal molecules. By virtue of the dislocation surface is formed like a lens shape.

However, the first electrode 11 is formed to be long in the shape of a rod in one direction, the potential surface is maintained the same in the longitudinal direction of the rod, the actual light path profile is as shown in Figure 2, the first electrode 11 It is formed in a parabolic shape only in the direction crossing the, and the same shape is maintained in the longitudinal direction of the first electrode 11.

Therefore, when viewed in the entire liquid crystal field lens provided with the unit lens cell in a matrix form, as shown in FIG. 2, the optical path profile is formed in a structure in which the semi-cylindrical lenses are repeated in parallel, thereby obtaining a lens effect according to the shape.

The conventional liquid crystal field lens as described above has the following problems.

In the conventional liquid crystal field lens, the lens is formed only in one direction, and stereoscopic image display is impossible when the viewer changes the viewing position. That is, when the viewer turns his face or squeezes the viewing area, the viewing area is deviated from the semi-cylindrical lens, so that even if the 3D image display device including the liquid crystal field lens emits a 3D image, the viewing area cannot be recognized. As described above, the conventional liquid crystal field lens has a limitation in that the stereoscopic image viewing area is limited to a specific direction.

An object of the present invention is to provide a liquid crystal field lens and a video display device using the same in which the field lens has a radially-even lens profile without directionality.

The liquid crystal field lens of the present invention for achieving the above object is each unit cell is defined in a matrix form, the first substrate and the second substrate facing each other; A plurality of first electrodes formed in the shape of a closed-loop that each share a center from the center to the outermost of each unit cell on the first substrate; A resistor for connecting the plurality of first electrodes, a second electrode formed on an entire surface of the second substrate; A liquid crystal layer between the first and second substrates; And first and second voltage terminals connected to the center and outermost first electrodes of the plurality of first electrodes, respectively, and configured to apply different voltages.

The second electrode may be any one of indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO).

The first electrode is made of any one of indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), copper, molybdenum, aluminum, or an alloy of two or more thereof. The resistor is a material having a lower conductivity than the first electrode.

The resistor has a shape in which the plurality of first electrodes are connected to each other in the direction from the center to the outermost. Here, a plurality of resistors are provided in symmetrical form with respect to each center of the unit cell.

In addition, the plurality of first electrodes may increase in width from the center to the outside and may be the same.

The plurality of first electrodes is a circular loop or a polygonal loop.

In addition, one of the first voltage terminal and the second voltage terminal is applied with a phase voltage of 1V or more, and the other is grounded.

The first and second voltage terminals are metal.

In addition, a first alignment layer and a second alignment layer may be further formed on the entire surface of the first substrate including the first electrode and the resistor, and on the second electrode.

In addition, an image display device may be implemented by including the above-described liquid crystal field lens and a display panel positioned below the liquid crystal field lens and outputting a two-dimensional image to the liquid crystal field lens side.

The liquid crystal field lens of the present invention and the image display device using the same have the following effects.

The electrodes forming the liquid crystal field lens are radially formed to uniformly form the dislocation surface of the liquid crystal field lens in all directions instead of one direction, thereby allowing the viewer to recognize a stereoscopic image regardless of a change in the attitude of the viewer.

In addition, in the shape of the electrode, by applying different voltages to each electrode included in the unit cell, an effective region in which an electric field is formed by simplifying the structure using a resistor, without using a method of increasing the number of wirings, and The opening area can be increased.

1 is a cross-sectional view showing a unit lens cell of a conventional liquid crystal field lens
2 is a perspective view illustrating an optical path profile when a plurality of unit lens cells of FIG. 1 are configured;
3 is a plan view illustrating a liquid crystal field lens according to a first exemplary embodiment of the present invention.
4 is a cross-sectional view taken along line II ′ of FIG. 3.
5 is a cross-sectional view taken along line II-II 'of FIG.
6 is a plan view illustrating a liquid crystal field lens according to a second exemplary embodiment of the present invention.
7 is a plan view illustrating a liquid crystal field lens according to a third exemplary embodiment of the present invention.
8 is a plan view illustrating a liquid crystal field lens according to a fourth exemplary embodiment of the present invention.

Hereinafter, the liquid crystal field lens of the present invention will be described in detail with reference to the accompanying drawings.

3 is a plan view illustrating a liquid crystal field lens according to a first exemplary embodiment of the present invention, FIG. 4 is a cross-sectional view taken along line II ′ of FIG. 3, and FIG. 5 is a cross-sectional view taken along line II—II ′ of FIG. 3.

3 to 5, the liquid crystal field lens according to the first exemplary embodiment of the present invention has a unit cell defined in a matrix form, and has a first substrate 110 and a second substrate 120 facing each other, and A plurality of first electrodes 113 having a closed-loop shape that shares a center from the center to the outermost of each unit cell on the first substrate 110, and the plurality of first electrodes Resistors 115 connecting the first and second electrodes 121 formed on the entire surface of the second substrate 120, the liquid crystal layer 150 between the first and second substrates 110 and 120, and the plurality of resistors. Each of the first electrodes 113 is connected to a first center electrode and an outermost first electrode, and includes first and second voltage terminals 111 and 117 for applying different voltages.

Here, the voltage value applied to the first voltage terminal 111 connected to the first electrode of the center and the second voltage terminal 117 connected to the outermost first electrode may be interchanged. That is, as shown in the figure, Vcc (high voltage or phase voltage) at the center and GND (ground) at the outermost side may be applied or changed.

At this time, any one of the first voltage terminal 111 and the second voltage terminal 117 is applied a phase voltage of 1V or more, and the other is grounded (GND). According to FIG. 3, the same Vcc and GND are applied to each center cell and the outermost center for each unit cell. However, in some cases, different voltage values are applied to the first and second voltage terminals separately for each unit cell, thereby providing an active method. It is also possible to drive the unit cells. Also in this case, one of the first and second voltage terminals is commonly grounded.

In addition, the first voltage terminal 111 and the second voltage terminal 117 may be formed on the same layer as shown, or may be formed on different layers. In view of saving the number of masks, it may be preferable to form the same layer as shown. In addition, the first and second voltage terminals 111 and 117 are metals to prevent the voltage from being applied.

Here, the second electrode 121 is formed of any one of indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO) as a transparent electrode.

The first electrode 113 is made of any one of indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), copper, molybdenum, aluminum, or an alloy of two or more thereof. In addition, the resistor 115 is a material having a lower conductivity than the first electrode 113.

Here, the first electrode 113 is preferably a transparent electrode such as ITO, IZO, ITZO, or the like, and in the case of copper, molybdenum, and aluminum, the thickness thereof is made thin to maintain transparency. According to the first exemplary embodiment of the present invention, the first electrodes 113 are illustrated in a circle having the same center, and the shapes of the first electrodes 113 are not necessarily limited thereto.

The resistor 115 has a shape in which the plurality of first electrodes 113 are connected to each other in a direction from the center to the outermost. As shown, it may be formed in a cross shape, in addition, a plurality of resistors 115 may be provided symmetrically with respect to the center of the unit cell. As illustrated, the resistor 115 may be positioned only between the first electrodes 113 or may be formed to pass through the surfaces of the first electrodes 113.

In addition, the widths of the plurality of first electrodes 113 may increase from the center to the outside and may be the same.

Here, the first electrodes 113 may be adjusted in consideration of the profile of the liquid crystal field lens to be formed.

In addition, a first alignment layer 116 and a second alignment layer 123 may be formed on the entire surface of the first substrate 110 including the first electrode 113 and the resistor 115, and on the second electrode 121, respectively. More is formed. The first and second alignment layers 116 and 123 may be rubbed in a direction parallel or perpendicular to the directions of the first electrodes 113 to control the initial liquid crystal direction.

Here, reference numerals 114 and 118 not described herein refer to first and second contact holes connected to the first and second voltage terminals 111 and 117 and the first electrode 113 at the upper side. 112 is a layer in which the first and second contact holes 114 and 118 are formed as an insulating layer, and the first and second voltage terminals 111 and 117 and the first electrodes 113 and the resistor 115 are disposed thereon. For interlayer insulation between layers.

In addition, 122 is used to support the cell gap of the liquid crystal layer 150 with a spacer, and the shape thereof may be changed into a circle, a polygonal column, or the like. Although the illustrated spacer 122 is formed outside the unit cell in order to prevent a decrease in the aperture ratio of the unit cell, the spacer 122 may be introduced into the unit cell as necessary.

In some cases, although not shown, a seal material may be formed at the edges of the unit cells to distinguish driving of the liquid crystal for each unit cell.

Hereinafter, the driving principle of the above-mentioned liquid crystal field lens will be described.

Vcc and GND (ground voltage) are applied to the center of the first electrodes 113 formed concentrically, and a common voltage (voltage lower than Vcc) or GND (ground voltage) is applied to the second electrode 121. When this is applied, the strongest vertical electric field is formed at the center, and the weakest or almost no electric field is formed at the outermost, so that the potential surface gradually lowers from the center of the first electrodes to the outer surface. Accordingly, the optical path difference occurs in the direction or the vertical direction along the dislocation surface, which causes the lens effect. Here, the arrangement of the liquid crystals depending on the potential plane or in the vertical direction depends on the properties of the liquid crystals, for example, dielectric anisotropy.

Here, the first electrodes 113 of the concentric circles form the same potential surface at the individual electrodes, and the resistor 115 may be spaced apart from each other by the intrinsic resistance of the resistor. The difference in voltage between the two, going from the center to the outermost or vice versa, adjusts the voltage drop.

When the liquid crystal field lens is implemented, an even field effect may be obtained in all directions, and thus the stereoscopic image may be visualized in any direction when the lens is provided by the above-described liquid crystal field lens.

In particular, the above-described liquid crystal field lens applies a voltage value only to the first electrode located at the center and the outermost part even if three or more electrodes are provided in the unit cells, thereby applying different voltage values to individual electrodes. The number of wirings can be reduced, the effective cell area can be increased, and the use of wirings using light shielding metals can be reduced to increase the aperture ratio.

On the other hand, the video display device of the present invention comprises a liquid crystal field lens described above, and a display panel positioned below the liquid crystal field lens and emitting a two-dimensional image to the liquid crystal field lens side.

As described above, the liquid crystal field lens functions as a liquid crystal field lens when Vcc and GND are applied to the first and second voltage terminals, and a common voltage is applied to the second electrode. When the terminal and the second electrode are both floated or grounded, they function as transparent cells and as switching cells.

Accordingly, 2D-3D image switching may be possible according to the application of the voltage of the liquid crystal field lens. That is, for example, when displaying a 2D image, the liquid crystal field lens functions as a transparent cell, and outputs an image as it is from the lower image panel, and when displaying a 3D image, Vcc is provided to the first and second voltage terminals. , GND is applied, and a common voltage is applied to the second electrode to function as a liquid crystal field lens.

The above-described mode for driving the liquid crystal field lens may be any of a twisted nematic (TN), an electrically controlled birefringence (ECB), a vertical alignment (VA), and a flexo-electric (flexo-electric).

Hereinafter, various embodiments of the liquid crystal field lens will be described.

6 is a plan view illustrating a liquid crystal field lens according to a second exemplary embodiment of the present invention.

FIG. 6 is a liquid crystal field lens according to a second embodiment of the present invention. In comparison with the first embodiment, the first electrodes 213 have the same width. As in the first embodiment, the resistor 215 may be formed only between the first electrodes 213, or may overlap the upper and lower surfaces with the resistors 215. In any case, the first electrodes 213 and the resistors 215 are connected at the side or the top.

Here, the part which is not demonstrated is the same as that of 1st Embodiment mentioned above.

7 is a plan view illustrating a liquid crystal field lens according to a third exemplary embodiment of the present invention.

As shown in FIG. 7, the liquid crystal field lens according to the third exemplary embodiment of the present invention is not different from the above-described second exemplary embodiment except that the first electrodes 313 are shaped like triangles.

In this case, the unit cells follow the shape of the triangle of the first electrode 313 located at the outermost part, and the arrangement of these unit cells on the entire first and second substrates is repeated with the triangle and the inverted triangle inverted. In this way, the effective area of the unit cell may be increased by forming a matrix.

8 is a plan view illustrating a liquid crystal field lens according to a fourth exemplary embodiment of the present invention.

As shown in FIG. 8, the liquid crystal field lens according to the fourth exemplary embodiment has the same structure as the above-described second exemplary embodiment except that the first electrode 413 has a rectangular shape.

On the other hand, the first electrodes of the liquid crystal field lens of the present invention are not limited to the above-described structures such as circles, triangles, squares, etc. for the radial electric field shape, but may be similarly or similarly applied to various deformation shapes of polygonal loops including the same. .

On the other hand, the present invention described above is not limited to the above-described embodiment and the accompanying drawings, it is possible that various substitutions, modifications and changes within the scope without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in Esau.

110: first substrate 111: first voltage terminal
112: insulating film 113: first electrode
114: first contact hole 115: resistor
116: first alignment layer 117: second voltage terminal
118: second contact hole 120: second substrate
121: common electrode 122: spacer
123: second alignment layer 150: liquid crystal layer

Claims (12)

Unit cells each defined as a matrix and having a first substrate and a second substrate facing each other;
A plurality of first electrodes formed in the shape of a closed-loop that each share a center from the center to the outermost of each unit cell on the first substrate;
A resistor connecting the plurality of first electrodes;
A second electrode formed on the entire surface of the second substrate;
A liquid crystal layer between the first and second substrates; And
And first and second voltage terminals connected to the center and outermost first electrodes of the plurality of first electrodes, respectively, for applying different voltages. The method of claim 1,
The second electrode is any one of indium tin oxide (ITO), indium zinc oxide (IZO), and indium tin zinc oxide (ITZO). The method of claim 1,
The first electrode is any one of indium tin oxide (ITO), indium zinc oxide (IZO), indium tin zinc oxide (ITZO), copper, molybdenum, aluminum, or a liquid crystal, characterized in that formed of two or more of these alloys. Electric field lens. The method of claim 1,
The resistor is a liquid crystal field lens, characterized in that the material having a smaller conductivity than the first electrode. The method of claim 1,
The resistor has a shape that connects the plurality of first electrodes in a direction from the center to the outermost in a straight line. 6. The method of claim 5,
And a plurality of resistors are provided in symmetrical form with respect to each center of the unit cell. The method of claim 1,
And a plurality of first electrodes extending in width from the center to the outside thereof. The method of claim 1,
And the plurality of first electrodes are circular loops or polygonal loops. The method of claim 1,
Any one of the first voltage terminal and the second voltage terminal is applied a phase voltage of 1V or more, and the other is grounded. The method of claim 1,
And the first and second voltage terminals are metal. The method of claim 1,
A first alignment layer and a second alignment layer are further formed on the entire surface of the first substrate including the first electrode and the resistor, and on the second electrode, respectively. 12. The image display device of claim 1, further comprising a liquid crystal field lens and a display panel positioned below the liquid crystal field lens and outputting a two-dimensional image toward the liquid crystal field lens.

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