KR20090003023A - Liquid crystal lens electrically driven and stereoscopy display device - Google Patents

Abstract

A liquid crystal lens electrically driven and stereoscopy display device are provided to reduce the cell gap of the liquid crystal layer by changing the arrangement of a buffer layer and electrode structure. A first and a second substrates(100,200) are placed corresponding to a plurality of lens areas facing with each other. A first electrode(101) is formed on the central part of the left and right lens area about the each lens area on the first substrate. The insulating layer is formed in the first top of the substrate including first electrode(102). The second electrode corresponding to the edge part of each lens region and is formed on the insulating layer(103). The buffer layer is formed on the insulating layer including second electrode(104).

Description

Liquid crystal field lens and three-dimensional display device using the same {Liquid Crystal Lens Electrically driven and Stereoscopy Display Device}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, in particular, by changing the arrangement of the buffer layer or the structure of the electrode to enable formation of the lens surface of the smooth parabolic surface when implementing the lens by the alignment of the liquid crystal, and to reduce the cell gap of the required liquid crystal layer. A liquid crystal field lens and a stereoscopic 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 develop into a hyper-spatial, 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 image 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.

That is, the lens is to control the path of the incident light by position by using the difference in refractive index between the material constituting the lens and the air, by applying different voltage to each position of the electrode to the liquid crystal layer by the different electric field When driven, the incident light incident on the liquid crystal layer feels a different phase change for each position. 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 showing a conventional liquid crystal field lens, and FIG. 2 is a view showing a potential distribution after voltage application when forming the liquid crystal field lens of FIG. 1.

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

Here, the first electrode 11 is formed on the first substrate 10 at a first separation distance from each other. 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 20.

The first and second electrodes 11 and 21 are made of a transparent metal. The liquid crystal layer 30 is formed in the liquid crystal layer 30 in the spaced space between the first and second electrodes 11 and 21, and the liquid crystal molecules constituting the liquid crystal layer 30 react to characteristics of the electric field. As a result, a phase distribution similar to that of the liquid crystal field lens of FIG. 2 is obtained.

The liquid crystal field lens is formed under a condition of applying a high voltage to the first electrode 11 and grounding the second electrode 21. The liquid crystal field lens is the strongest at the center of the first electrode 11 under such a voltage condition. A vertical electric field is formed, and a weak vertical electric field is formed as it moves away from the first electrode 11. Accordingly, when the liquid crystal molecules constituting the liquid crystal layer 30 have positive dielectric anisotropy, the liquid crystal molecules are arranged in accordance with an electric field, and stand at the center of the first electrode 11, and the first electrode 11. The farther away from), the closer to horizontal the slanted array will be. Therefore, from the standpoint of light transmission, the center of the first electrode 11 has a short optical path, and the farther away from the first electrode 11, the longer the optical path becomes. As in the liquid crystal field lens of FIG. 2, the surface has a light transmission effect similar to that of a lens having a parabolic surface.

Here, the second electrode 21 induces the behavior of the liquid crystal electric field, thereby inducing the refractive index of light as a whole to be a spatial parabolic function, and the first electrode 11 forms an edge portion (edge area) of the lens. Do it.

At this time, a voltage slightly higher than that of the second electrode 21 is applied to the first electrode 11, so that a potential difference occurs between the first electrode 11 and the second electrode 21 as shown in FIG. 2. By doing so, in particular, the first electrode 11 is caused to cause a sudden side electric field. Accordingly, the liquid crystal does not form a smooth distribution, but rather forms a distorted shape, thereby making it impossible to form a spatial refractive index in a parabolic form or very sensitive to voltage.

On the other hand, as shown in Figure 2, it can be seen that the liquid crystal is in contact with the portion where the potential distribution is rapidly changed by the voltage applied to the first electrode (11).

Such a liquid crystal field lens can be obtained by forming an electrode on both substrates with a liquid crystal interposed between the liquid crystal and the liquid crystal without applying a lens having a physically parabolic surface, and applying a voltage thereto.

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

That is, the liquid crystal is positioned immediately adjacent to the electrode structurally, and the liquid crystal is disposed at a portion where the potential distribution changes rapidly. Therefore, the liquid crystal moves very sensitively to voltage, so that the alignment of the liquid crystal rapidly occurs due to the application of voltage, thereby making it difficult to form a smooth liquid crystal electric field. In addition, the electrode formed on the lower plate is formed only at a portion of the lens region, so that an electric field between the lens edge region corresponding to the electrode and the lens center region away from the electrode is not formed smoothly, causing a sudden lateral electric field, thereby causing some distortion. It is formed to have a liquid crystal field lens of the phase.

The present invention has been made to solve the above problems, it is possible to form the lens surface of the smooth parabolic surface when implementing the lens by the alignment of the liquid crystal by changing the arrangement of the buffer layer or the electrode structure, the cell gap of the required liquid crystal layer It is an object of the present invention to provide a liquid crystal field lens and a stereoscopic display device using the same.

In the liquid crystal field lens of the present invention for achieving the above object, a plurality of lens regions are defined corresponding to each other, for each of the first and second substrates and the lens regions on the first substrate, A first electrode formed between the centers of adjacent left and right lens regions, a first insulating film formed on the first substrate including the first electrode, and an edge portion of each lens region on the first insulating film A second electrode formed, a buffer layer formed on the first insulating film including the second electrode, a third electrode formed on the second substrate, and a liquid crystal layer filled between the first substrate and the second substrate. It is characterized by what is done.

The buffer layer is photo acrylic or BCB (Benzene CycloButene). At this time, the dielectric constant of the buffer layer is smaller than that of the liquid crystal layer. The buffer layer has a thickness of 1 ~ 10㎛.

On the other hand, the first electrode is formed symmetrically with respect to the left and right adjacent lens area bordering the second electrode.

Further, first and second alignment layers are further formed on the buffer layer and the third electrode, respectively. In this case, the first alignment layer is rubbed in the longitudinal direction of the second electrode, and the second alignment layer is rubbed in a direction crossing the rubbing direction of the first alignment layer.

The first and third electrodes are formed of a transparent metal, and the second electrode is formed of a light blocking metal.

In addition, when driving the liquid crystal layer, an AC voltage having a peak value of 1.6 to 2 V is applied to the first electrode, an AC voltage having a peak value of 2.5 to 15 V is applied to the second electrode, and the third electrode is applied. Is grounded.

The interlayer between the first substrate and the first insulating film including the first electrode may further include a fourth electrode formed on the entire surface of the first substrate via the second insulating film.

In addition, the liquid crystal field lens of the present invention for achieving the same object is defined by a plurality of lens areas corresponding to each other, the first and second substrates disposed opposite to each other, the first electrode formed on the front surface of the first substrate, A first insulating film formed on the first substrate including a first electrode, a second electrode formed on the first insulating film between centers of adjacent left and right lens areas with respect to each lens area, and the second electrode A second insulating film formed on the first insulating film including a second insulating film, a third electrode formed on the second insulating film corresponding to an edge portion of each lens region, a fourth electrode formed on the entire surface of the second substrate, and the second Another feature is that the liquid crystal layer is filled between the first substrate and the second substrate.

First and second alignment layers may be further formed on the second insulating layer and the fourth electrode including the third electrode, respectively. In this case, it is preferable that the first alignment layer is rubbed in the longitudinal direction of the second electrode, and the second alignment layer is rubbed in a direction crossing the rubbing direction of the first alignment layer.

Meanwhile, the first, second and fourth electrodes are formed of a transparent metal, and the third electrode is made of a light shielding metal.

The overcoil layer may be further formed on the second insulating layer including the third electrode.

When driving the liquid crystal layer, an AC voltage of 0 to 1.6 V is applied to the first electrode, an AC voltage having a peak value of 1.6 to 2 V is applied to the second electrode, and 2.5 to 10 V is applied to the third electrode. An AC voltage having a peak value is applied, and the fourth electrode is grounded.

In addition, in order to achieve the same object, the stereoscopic display device according to the present invention may include the above-described liquid crystal field lens and a display panel configured to emit two-dimensional first and second images under the liquid crystal field lens. have.

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

First, a buffer layer such as an overcoat layer is formed between the liquid crystal layer and the electrode so that the abrupt electric field change does not directly contact the liquid crystal layer. Accordingly, the liquid crystal field lens may be formed in the buffer layer to include a portion where a strong electric field change occurs at the edge of the lens, and a smooth parabolic surface may be formed in the liquid crystal layer substantially implementing the liquid crystal lens.

Secondly, the second electrode is formed between the center of the lens region adjacent to the lower plate side and the third electrode formed corresponding to the center of the second electrode without increasing the number of masks. In forming one electrode and applying a voltage to the fourth electrode formed on the opposite substrate side to form a vertical electric field to align the liquid crystal to form a liquid crystal electric field lens, the formation of a more gentle electric field is achieved by the multilayer electrode configuration. It is possible to form a liquid crystal field lens having a gentle parabolic surface.

Third, the formation of a smooth liquid crystal field, that is, the size of the sag (the height of the liquid crystal field lens) can be reduced, thereby reducing the cell gap of the required liquid crystal layer, thereby reducing the amount of liquid crystal required for injecting or dripping the liquid crystal. This can reduce the process burden.

Fourth, it is possible to widen the pitch of the lens region that can be formed by the gentle liquid crystal electric field, thereby increasing the number of views that can be seen in one lens region, and thus can be used in a large area display device. As a result, multi-view is possible, thereby improving the visibility of the stereoscopic display device.

Hereinafter, a liquid crystal field lens and a stereoscopic display device using the same will be described in detail with reference to the accompanying drawings.

First Embodiment

3 is a cross-sectional view illustrating a stereoscopic display device using a liquid crystal field lens according to a first exemplary embodiment of the present invention, FIG. 4 is a cross-sectional view showing the liquid crystal field lens of FIG. 3, and FIG. 5 is a diagram illustrating a voltage applied to the structure of FIG. 4. FIG. 6 is a graph illustrating a potential distribution and a liquid crystal molecular array distribution, and FIG. 6 is a graph illustrating phases according to positions of liquid crystal field lenses obtained through FIGS. 4 and 5.

As shown in FIG. 3, the display device including the liquid crystal field lens according to the first exemplary embodiment of the present invention includes a liquid crystal field lens 10000 having a lens function driven under voltage application, and a lower side of the liquid crystal field lens 10000. And a light source 700 for transmitting light to the display panel 350 under the display panel 350.

In some cases, if the display panel 350 directly emits light, the light source 700 may be omitted.

The display panel 350 sequentially repeats the first and second image pixels P1 and P2 for displaying the first and second images IM1 and IM2, respectively. Flat display such as liquid crystal display division (LCD), organic light emitting display device (OLED), plasma display panel (PDP), and field emission display device (FED) The device can be used.

3 to 6, when a threshold voltage, a high voltage, and a ground voltage are applied to the first, second, and third electrodes 101, 103, and 201 of the liquid crystal field lens 10000, respectively, the liquid crystal field The lens 10000 functions as a lens similar to a parabolic optical lens, and the first and second images IM1 and IM2 emitted from the display panel 350 are respectively formed by the liquid crystal field lens 10000. When the distance between the first and second viewing zones V1 and V2 is transmitted and the distance between the first and second viewing zones V1 and V2 is designed as the distance between two eyes of a person, the user may select the first and second viewing zones V1 and V2. The first and second images IM1 and IM2 transmitted to the two viewing areas V1 and V2 are respectively synthesized to recognize a 3D image due to binocular disparity.

Meanwhile, when no voltage is applied to the first, second, and third electrodes 101, 103, and 201, the liquid crystal field lens 10000 may display the first and second images IM1, of the display panel 350. It acts as a simple transparent layer that is displayed as it is without refraction of IM2). Accordingly, the first and second images IM1 and IM2 are transmitted to the user without the visual field classification, and the user recognizes the 2D image.

In the drawing, one lens area L of the liquid crystal electric field 10000 is formed to correspond to the width of two pixels P1 and P2 of the display panel 350 positioned under the liquid crystal field lens. In some cases, a plurality of pixels may be formed corresponding to the one lens area L. FIG. In addition, the lens regions L may be formed in a direction inclined at a predetermined angle with respect to the pixels, and in some cases, a stepped shape with respect to the pixels (the lens arrangement is (n + 1) th with respect to the nth pixel horizontal line). The width may be shifted by a predetermined width on the pixel horizontal line side).

The lens region L is defined to have a width corresponding to one pitch, and the lens region L having the same pitch is periodically repeated in one direction (the horizontal direction in FIG. 4). In this case, one pitch refers to the width of the lens region L, and the lens region does not have a physical lens shape as shown in the convex lens, but a lens function formed by liquid crystal arrangement according to application of an electric field. It is an area with.

Hereinafter, the liquid crystal field lens 10000 will be described in detail.

In the liquid crystal field lens 10000, a plurality of lens regions are defined to correspond to each other, and the first and second substrates 100 and 200 disposed to face each other, and the lens regions on the first substrate 100, respectively. A first electrode 101 formed between the centers of adjacent left and right lens regions, an insulating film 102 formed on the first substrate 100 including the first electrode 101, and on the insulating film 102. A second electrode 103 formed corresponding to an edge portion of each lens region, a buffer layer 104 formed on the insulating layer 102 including the second electrode 103, and the second substrate 200. And a liquid crystal layer 300 filled between the third electrode 201 and the first substrate 100 and the second substrate 200 formed on the front surface.

Here, the buffer layer 104 disposed on the second electrode 103 is a low dielectric constant organic film component such as photo-acryl or BCB (BenzeneCycloButene), for example, such as an overcoat layer. The surface is formed flat in shape, has a thickness of about 1 to 10 μm, and uses a material of an organic component having a lower dielectric constant than that of the liquid crystal layer 300.

Here, the buffer layer 104 buffers a strong electric field formed between the third electrode 201 and the second electrode 103. In particular, the abrupt change in the electric field is alleviated by the arrangement of the buffer layer 104 having a thickness of several micrometers on the upper side of the second electrode 103. In this case, since the dielectric constant of the buffer layer 104 is small with respect to each of the long and short dielectric constants of the liquid crystal layer 300, the electric field shows a phenomenon that the dielectric constant is more concentrated on the smaller one, so that the liquid crystal layer on the buffer layer 104 is substantially 300 forms a gentle dislocation distribution than in the buffer layer 104, as shown in FIG.

As a result, the liquid crystal molecules of the liquid crystal layer 300 have an arrangement that rises as a whole near the second electrode 103 but lie gently as it moves away from the second electrode 103. According to the electric field effect and the liquid crystal arrangement according to the graph, a strong electric field induced by the second electrode 103 is mostly generated in the buffer layer 104, and in fact, in the liquid crystal layer 300, it is gentle according to a gentle electric field. It can be seen that it forms a parabolic surface. That is, from the viewpoint of light transmission, the optical path becomes shorter at the center of the second electrode 103, and the longer the optical path becomes, the farther it is from the second electrode 103. 6, it can be seen that a liquid crystal field lens having a phase having substantially the same light transmission effect as a half-divided parabolic lens bilaterally symmetrical is formed around the second electrode formation site.

The liquid crystal field lens 10000 according to the first exemplary embodiment of the present invention serves as a lens used in a three-dimensional implementation by itself, and as shown in FIG. 3, is positioned above the display panel 350 implementing two-dimensional. In addition, the present invention may be used as a switching means for converting a 2D image into a 3D image and displaying the image. That is, by utilizing the characteristic that light is transmitted when no voltage is applied, it is possible to use a switching function such as two-dimensional display when no voltage is applied and three-dimensional display when voltage is applied. That is, the switching function of the two-dimensional image display and the three-dimensional image display is possible, so that the liquid crystal field lens enables stereoscopic (three-dimensional) image display of the two-dimensional image signal from the lower display device when voltage is applied. When no voltage is applied, the 2D image display from the lower display device 350 may be directly transmitted to the observer to display the 2D image.

At this time, as shown in FIG. 4, light is transmitted to the first and second substrates 100 and 200 in an initial state (when no voltage is applied) to enable the two-dimensional image display when no voltage is applied to the liquid crystal field lens 10000. Is oriented as possible. In other words, the first and second alignment layers 105 and 202 may have an alignment characteristic in which the liquid crystal layer 300 transmits light in an initial state where no voltage is applied. Rubbing in the direction of the second electrode 103 (the direction passing through the ground on the drawing), and the second alignment layer 202 is anti-parallel in the direction crossing it. Here, the back side of the first and second substrates 100 and 200 is not provided with a polarizing plate, and thus the light passing through the liquid crystal field lens 10000 through the display device 350 from the bottom is not directly observed. It is transmitted through and transmitted to.

The liquid crystal field lens according to the first exemplary embodiment of the present invention has the same effect as the lens having the parabolic surface when the voltage is applied to each electrode. The effect of recognizing the signal enables three-dimensional implementation for the observer.

Particularly, in the liquid crystal field lens of the present invention, the second electrode 103 in the highly distorted lens edge region (near the second electrode) is used as a light shielding metal, and the light shielding is performed on the second electrode 103. It is possible to improve the crosstalk caused by incorrect information applied to the left and right eyes, respectively, in the vicinity of the?

Meanwhile, when looking at the vertical distance between the first electrode 101 and the second electrode 103 with respect to the third electrode 201, the second electrode 103 is compared with the first electrode 101. It can be seen that the distance is close to the third electrode 201. In addition, since the second electrode 103 is relatively high in voltage, the influence of the electric field due to the voltage difference between the second electrode 103 and the third electrode 201 is strongly affected. Here, the function of the first electrode 101 is to give a relatively small voltage value compared to the high voltage, to enable the control of the electric field of the portion where the second electrode 103 is not formed, the field formation is not abrupt It is possible to adjust the magnitude of the phase of the liquid crystal field lens obtained based on the alignment characteristics of the liquid crystals arranged along the electric field together with the second electrode 103.

The first and second electrodes 101 and 103 are formed in a rod shape extending in a direction perpendicular to the drawing (direction passing through the drawing).

In addition, the one lens area L is formed to correspond to the pixels P1 and P2 of the display panel 350 positioned below the liquid crystal field lens, and a plurality of pixels correspond to the one lens area L. Can be formed. In addition, the lens regions L may be formed in a direction inclined at a predetermined angle with respect to the pixels, and in some cases, a stepped shape (n + 1) horizontal line with respect to the nth horizontal line may be formed with respect to the pixels. May be shifted by a certain width).

The lens region L is defined to have a width corresponding to one pitch, and the lens region L having the same pitch is periodically repeated in one direction (the horizontal direction in FIG. 4). In this case, one pitch refers to the width of the lens region L, and the lens region does not have a physical lens shape as shown in the convex lens, but a lens function formed by liquid crystal arrangement according to application of an electric field. It is an area with.

(Δε는 액정 유전율 이방성, K1은 액정의 자유 상태(Splay) 탄성 계수, ε₀은 자유공간 유전율) 을 피크값으로 하는 교류 사각파(square wave)이며, 상기 제 2 전극(103)에 인가되는 전압은 상기 2.5~15V를 피크값으로 하여 인가되는 교류 사각파이다. 4 is a cross-sectional view showing an area between the centers of the left and right adjacent lens regions (the second electrode 103 becomes the edge portion of the left and right adjacent lens regions, and the 'O' point mark represents the center of the left and right lens regions. ) Is a cross-sectional view of a width corresponding to one pitch of the lens region. In this case, a high voltage of about 2.5 to 15V and a threshold voltage of 1.6 to 2V are applied to the second electrode 103 and the first electrode 101, respectively, and a ground voltage is applied to the opposing third electrode 201. In this case, a difference in refractive index occurs depending on the orientation of the liquid crystal by the electric field, and thus the liquid crystal having phase characteristics of each half-divided parabolic surface of the adjacent left and right lens regions L with respect to the center of the second electrode 103. An electric field lens is formed. Here, the voltage applied to the first electrode 101 is V =

(Δε is the liquid crystal dielectric anisotropy, K1 is the free state (Splay) elastic modulus of the liquid crystal, ε ₀ is a free square dielectric constant) is an alternating square wave (peak) is applied to the second electrode 103 The voltage is an AC square wave applied with the above 2.5 to 15V as the peak value.

When the pattern of the same structure is repeated in one direction (horizontal direction), the parabolic liquid crystal field lens is continuously formed at one pitch.

Although not shown, a seal pattern (not shown) is formed in the outer regions of the first and second substrates 100 and 200 to support the first and second substrates 100 and 200. In addition, the liquid crystal layer 300 between the first and second substrates 100 and 200 is formed to a sufficient thickness to form a liquid crystal electric field lens of sufficient phase, and maintains the thickness of the liquid crystal layer 300 stably. To this end, a ball spacer or a column spacer supporting the cell gap between the first and second substrates 100 and 200 may be further formed. In this case, the included spacers are preferably formed at positions where the phases of the liquid crystal field lenses are not distorted.

Here, the first electrode 101 and the third electrode 201 are formed of a transparent electrode, the second electrode 103 is made of a light shielding metal. In this case, as shown in FIG. 5, the portion of the second electrode 103 formed of the light shielding metal is covered by the second electrode 103. In this case, a high voltage is applied to the second electrode 103, and most of the strong electric fields between the second electrode 103 and the third electrode 201 concentrate on the buffer layer 104 having a low dielectric constant. do. The buffer layer 104 is transparent, and transmits light emitted through the display panel 350 from the bottom with concentration of an electric field.

In the case of the liquid crystal field lens according to the first embodiment of the present invention having such a configuration, the effective field lens of the parabolic surface is formed only on the liquid crystal layer above the buffer layer, and the electric field itself is formed on the liquid crystal layer including the buffer layer. The thickness of the liquid crystal layer in which the effective liquid crystal field lens is formed can be reduced to a considerable extent to the thickness of the buffer layer. As a result, when the liquid crystal layer is formed between the first and second substrates, the amount of liquid crystal can be reduced by the reduced cell gap thickness, thereby reducing the burden of the liquid crystal layer formation process during vacuum injection or dripping to form the liquid crystal layer. have.

In this case, the voltage applied to the second electrode 103 side is such that a vertical electric field between the second electrode 103 and the third electrode 201 sufficiently affects the liquid crystal layer 300. Relatively high voltage, for example, about 1.5 times higher than the structure having no buffer layer is preferably applied. That is, in the general electrode structure without the buffer layer 104, when the voltage applied to the electrode formed on the lower plate is about 2.5 to 10V, the voltage applied to the second electrode 103 is applied to 2.5 to 15V.

Referring to FIG. 5, when the buffer layer 104 has a thickness of about 5 μm, the thickness of the liquid crystal layer 300 may be about 10 μm. In this case, that is, the electric field is formed to reduce the thickness of the liquid crystal layer 300 by an electric field corresponding to the surface height of the buffer layer 104 formed at the interface of the first substrate (not shown). That means you can. Here, the pitch of the lens region is about 94 µm, and the display panel used for the simulation is a small model having a width of 50 µm or less for each unit subpixel (R, G, B subpixel).

In addition, the buffer layer 104 is further formed on the second electrode 103 so that the abrupt electric field change caused by the second electrode 103 does not directly contact the liquid crystal layer 300. At this time, if the dielectric constant of the buffer layer 104 is smaller than the long / short dielectric constant of the liquid crystal molecules constituting the liquid crystal layer 300, the electric field is more concentrated on the smaller dielectric constant, the buffer layer 104 Includes a site where a severe electric field is formed, and the liquid crystal layer 300 includes a gentle potential distribution. As a result, since the liquid crystal molecules of the liquid crystal layer 300 generally have a shape that rises gently and is lying down, the further away from the center of the second electrode 103 in the refractive index of FIG. It can be formed close to the smooth parabolic lens surface (dotted line). That is, the phase of the liquid crystal field lens (solid line) is formed in the form of a parabolic lens surface with a gentle phase.

In addition, the liquid crystal field lens sensitive to voltage fluctuation can be formed less sensitive to voltage, and the height (sag) of the liquid crystal field lens is lowered due to the gentle parabolic surface (single-dashed line) effect, and thus the liquid crystal layer 300 Cell gap may be reduced. That is, the buffer layer 104 is used as a portion where an electric field is formed together with the liquid crystal layer 300, and also includes a portion where a severe change occurs when the electric field is formed, thereby providing a buffer function for the liquid crystal layer 300. Will have.

Second Embodiment

7 is a cross-sectional view of a stereoscopic display device using a liquid crystal field lens according to a second exemplary embodiment of the present invention.

As illustrated in FIG. 7, the display device including the liquid crystal field lens of the present invention emits two-dimensional image information under the liquid crystal field lens 1000 and the liquid crystal field lens 1000 that are driven by voltage and have a lens function. And a light source 700 for transmitting the light of the display panel 350 to the lower side of the display panel 350.

In some cases, if the display panel 350 directly emits light, the light source 700 may be omitted.

The display panel 350 sequentially repeats the first and second image pixels P1 and P2 for displaying the first and second images IM1 and IM2, respectively. Flat panel such as liquid crystal display division (LCD), organic light emitting display device (OLED), plasma display panel (PDP), and field emission display device (FED) Display devices can be used.

When a positive voltage, a threshold voltage, a high voltage, and a ground voltage smaller than a threshold voltage are respectively applied to the first to fourth electrodes 401, 403, 405, and 501 included in the liquid crystal field lens 1000, the liquid crystal field lens ( The lens 1000 acts as a lens similar to a parabolic optical lens, and the first and second images IM1 and IM2 emitted from the display panel 350 are respectively formed by the liquid crystal field lens 1000. When the distance between the first and second viewing zones V1 and V2 is transmitted to the second viewing zone V1 and V2 and the distance between the two eyes of a person is designed, the user may view the first and second viewing zones. The first and second images IM1 and IM2 delivered to (V1 and V2) are respectively synthesized to recognize a 3D image by stereo graphics.

Meanwhile, when no voltage is applied to the first to fourth electrodes 401, 403, 405, and 501, the liquid crystal field lens 1000 is rubbed in the directions of the second and third electrodes 403 and 405, respectively. The display panel may be formed by the liquid crystal layer 600 which is horizontally oriented from the first alignment layer 406 to the second alignment layer 502 by the first alignment layer 406 and the second alignment layer 502 that is aligned to cross each other. It serves as a simple transparent layer that is displayed as it is without refraction of the first and second images IM1 and IM2 of 350. Accordingly, the first and second images IM1 and IM2 are transmitted to the user without the visual field classification, and the user recognizes the 2D image.

8 is a plan view showing a pixel array corresponding to the liquid crystal field lens of FIG. 7, FIG. 9 is a plan view showing an electrode on a second substrate of the liquid crystal field lens, and FIG. 10 is a first substrate of the liquid crystal field lens. It is a top view which shows the electrode of phase. 11 is a cross-sectional view illustrating the liquid crystal field lens of FIG. 7, and FIG. 12 is a perspective view illustrating the liquid crystal field lens of FIG. 7.

As shown in FIGS. 8 to 12, the liquid crystal electric field which is located above and emits a 2D video signal as a 3D video signal with respect to the display panel 350 in which the R, G, and B video signals are output in a stripe type, respectively. The lens 1000 is located.

Here, as shown in FIG. 8, the display panel 350 includes R, G, and B subpixels per pixel, and the width of the one pixel is one lens area L of the liquid crystal field lens. Corresponds to the pitch of The display panel 350 may use a liquid crystal panel capable of displaying two-dimensional images, an organic electroluminescence (EL) panel, a PDP panel, or the like.

In addition, as shown in FIG. 9, the liquid crystal field lens includes a first electrode 401 formed on the front surface of the first substrate 400 (see FIGS. 11 and 12) and a second electrode 403 formed between the centers of adjacent left and right lens regions. And a third electrode 405 positioned at the center of the second electrode 403 and corresponding to an edge portion of the lens region L, as shown in FIG. 10. 500: see FIG. 11 and FIG. 12, the fourth electrode 501 is formed.

Here, in the drawing, the pitch of the lens area is determined to correspond to the widths of the R, G, and B columns of the display panel 350, and the edge of each lens area is determined by the display panel 350. It is shown to be located corresponding to the G column. The width of the lens area corresponding to the display panel 350 may be changed in some cases. Accordingly, a portion of the display panel 350 corresponding to the edge of the lens region L may also have a different position and period.

Experimentally, it can be seen that the longer the length of the first electrode 401, the light path of the formed liquid crystal field lens may be less sensitive to voltage. By using this, the width of the first electrode 401 is maximized, that is, the transparent first electrode 401 is formed on the entire surface of the first substrate 400. The transparent second electrode 403 is formed on the first electrode 401 to be spaced apart from the center of the adjacent lens region, and the metal pattern corresponds to the central portion of the second electrode 403. To form a third electrode 405. That is, the first electrode 401 can be formed without increasing the mask, and a gentle lens shape having a wide lens pitch and low cell gap can be formed.

(Δε는 액정 유전율 이방성, K1은 액정의 탄성 계수, ε₀은 자유공간 유전율)로 계산되며, 이를 피크값으로 하는 교류 사각파(square wave)로 인가되며, 상기 제 1 전극(401)에는 이보다 작은 값을 피크값으로 하는 교류 사각파, 상기 제 3 전극(405)는 약 2.5~10V를 피크값으로 하여 인가되는 교류 사각파이다. In this case, a threshold voltage of 1.6 to 2 V is applied to the second electrode 403, a high voltage of about 2.5 to 10 V is applied to the third electrode 405, and a ground voltage (0 V) is applied to the fourth electrode 501. Is applied. In addition, a voltage value between a ground voltage (0V) and a voltage (1.6 to 2V) applied to the second electrode 403 is applied to the first electrode 401. Here, the threshold voltage applied to the second electrode 403 is V =

(Δε is calculated by the liquid crystal dielectric anisotropy, K1 is the elastic modulus of the liquid crystal, ε ₀ is the free-space dielectric constant), and is applied as an AC square wave with the peak value, and is applied to the first electrode 401 An AC square wave having a small value as a peak value, and the third electrode 405 is an AC square wave applied with a peak value of about 2.5 to 10V.

A vertical electric field is formed between the first and second substrates 400 and 500 facing each other by applying the voltage, and the first to third electrodes 401, 403, and 405 formed on the first substrate 400 are formed. As a result, the electric field formed between the first and second substrates 400 and 500 is formed as a side electric field in which a parabolic curve is drawn gently.

That is, the liquid crystal field lens according to the second embodiment of the present invention will be specifically described with reference to FIGS. 11 and 12.

A plurality of lens regions are defined to correspond to each other, and are disposed to face each other, the first and second substrates 400 and 500, the first electrode 401 formed on the entire surface of the first substrate 400, and the first electrode ( A first insulating layer 402 formed on the 401, a second electrode 403 formed between the centers of the adjacent left and right lens regions with respect to each of the lens regions, and the second electrode 403 including the second electrode 403. The second insulating film 404 formed on the first insulating film 402, the third electrode 405 formed on the second insulating film 404 corresponding to the edge portion of each lens region, and the second substrate ( And a liquid crystal layer 600 filled between the fourth electrode 501 and the first substrate 400 and the second substrate 500 formed on the entire surface of the substrate 500.

In the liquid crystal field lens according to the second exemplary embodiment, a first electrode 401 having a relatively large area and a low voltage applied thereto is formed in addition to the second electrode 403 to which a threshold voltage is applied. The potential surface formed between 405 and the fourth electrode 501 is lowered, thereby lowering the height of the resulting liquid crystal field lens, that is, sag, and thus the liquid crystal electric field. Since the liquid crystal having a thickness in which the lens is not formed may be omitted, the thickness of the liquid crystal layer 600 may be reduced.

In addition, a buffer layer may be formed on the second insulating layer 404 including the third electrode 405. A buffer layer (not shown) is provided at a portion where a voltage change is severe in accordance with the above-described principle, thereby substantially liquid crystal. In the layer 600, a more parabolic liquid crystal field lens can be formed.

Although the liquid crystal molecules constituting the liquid crystal layer 600 have a positive dielectric anisotropy in FIG. 3, unlike the liquid crystal field lens illustrated in FIG. 3, a shifted liquid crystal field lens is intended. Alternatively, even in the case of forming a liquid crystal field lens having the same effect as shown, the electrode disposed on the first substrate 400 is different, or the positions of the first and second substrates 400 and 500 are inverted. It is also possible to use a material having negative dielectric anisotropy.

On the other hand, the liquid crystal field lens 1000 of the present invention serves as a lens used in the three-dimensional implementation itself, and in some cases, is located on the display device for implementing the two-dimensional, converting the two-dimensional image to a three-dimensional image To display an image. In addition, by utilizing the characteristic that light is transmitted when no voltage is applied, it is possible to use a switching function such as two-dimensional display when no voltage is applied and three-dimensional display when voltage is applied. Such a liquid crystal field lens may be used by placing a display device capable of displaying a two-dimensional image at a lower portion thereof. That is, the switching function of the two-dimensional image display and the three-dimensional image display is possible, and the liquid crystal field lens enables stereoscopic (three-dimensional) image display of the two-dimensional image signal from the lower display device when voltage is applied. When no voltage is applied, the 2D image display from the lower display device is directly transmitted to the observer, thereby enabling the 2D image display.

At this time, the first and second substrates 400 and 500 are oriented so that light can be transmitted in an initial state (when no voltage is applied) to enable two-dimensional image display when no voltage is applied. That is, the first and second alignment layers 406 and 502 may have an alignment characteristic in which the liquid crystal layer 600 transmits light in an initial state where no voltage is applied. Rubbing with the three electrodes 405, and the second alignment layer 502 is anti-parallel in the direction crossing it. Here, the back side of the first and second substrates 400 and 500 is not provided with a polarizing plate, so that the light passing through the liquid crystal field lens from the bottom through the display device is transmitted to the viewer as it is.

In the liquid crystal field lens of the present invention, when the voltage is applied to each electrode, the liquid crystal layer 600 has the same effect as the lens having a parabolic surface, and when used, a three-dimensional implementation of an image signal is possible.

In particular, the liquid crystal field lens of the present invention covers a portion where the change in the liquid crystal field is severe with the buffer layer, thereby substantially reducing the change in the electric field of the liquid crystal layer, so that the liquid crystal field lens can be gently adjusted, and the height can be adjusted.

Hereinafter, the liquid crystal field lens and the liquid crystal field lens having a three-electrode structure having no buffer layer according to the second embodiment of the present invention will be compared and explained through simulated data.

FIG. 13 is a lenticular simulation diagram of a liquid crystal field lens with three electrodes without a buffer layer, and FIG. 14 is a lenticular simulation diagram of a liquid crystal field lens with four electrodes of the present invention.

When the liquid crystal field lens was formed of three electrodes without a separate buffer layer in addition to the liquid crystal layer, deviation from the surface thereof was severe compared to the parabolic surface as shown in FIG. 13, while the liquid crystal field lens was formed of four electrodes as shown in FIG. 14. The eye is observed to have a phase similar to the parabolic surface. Here, in FIG. 13 and FIG. 14, the second electrode and the third electrode to which the high voltage is applied, respectively, are made of light shielding metal, and thus the lens is not formed, and the light shielding area is the same. .

The values obtained by simulating the liquid crystal field lenses of FIGS. 13 and 14 will be described as an example.

For example, when the ratio of the cell gap is about 10: 1 (experimentally, one pitch of the lens region is 200 µm and the cell gap of the liquid crystal layer is 20 µm), the three-electrode structure is formed when the lens profiles are formed at optimum voltages, respectively. It can be seen that does not have a normal lens profile (parabolic lens surface). This is because the larger the pitch of the lens region, the larger the cell gap of the liquid crystal layer, which should include at least the vertex of the lens (the point where the height of the lens is) due to the phase formed at the second electrode position. However, as shown in FIG. 14, in the case of the four-electrode structure, since the first electrode formed on the first substrate is gradually smaller from the first electrode to the third electrode, a larger voltage is applied, so that the side electric field is more gentle. In addition, the vertical phase is similarly formed on the smooth parabolic lens surface, and thus, it is possible to form a liquid crystal field lens having no large lens surface difference compared to the physically formed parabolic lens.

Experimentally, the pitch of the lens region was set to 200 µm, where the width of the second electrode was about 180 µm, about 9/10 of that, and the third electrode was 10, which is 1/20 of the lens region. It is the profile of the liquid crystal field lens obtained as micrometer. Depending on the pitch and sag of the lens required, the respective widths and magnifications will vary.

The liquid crystal field lens observed in the above-described simulation is capable of two views (view: the number of subpixels in one field of view) or three views, and is easy to apply to small and medium-sized panels. In a large-area display device in which a single pixel of a large is enlarged, an example of experimenting by increasing the number of views of the lens area will be described.

15A and 15B are simulation views showing an arrangement structure and a lens shape when a 9-view liquid crystal field lens is implemented by three electrodes without a buffer layer, and FIGS. 16A and 16B are 9-view liquid crystal field lenses. Is a simulation diagram showing an arrangement structure and a lens shape thereof when the four electrodes and the buffer layer are implemented together.

In order to implement 9 views, the pitch should be increased so that 4.5 sub-pixels and 2 sub-pixels (R, G, and B subpixels) enter the length of one lens region. In the simulation of FIG. 15A of the three-electrode structure, the pitch was set to 730 µm, and the width of the second electrode was set to about 90 µm in order to sufficiently effect the electric field in the one lens region. 15B, in this case, looking at the lens profile according to the electric field change of the liquid crystal layer, it can be seen that the deviation from the shape of the parabolic lens is severe. In particular, in a region where the vertical electric field is strongly applied to the vicinity of the second electrode and between the second electrode and the third electrode (electrode formed on the opposite substrate side), the inclination of the parabolic lens increases, and the lens center region (Fig. The optical paths become smaller each week than the left and right edges, resulting in an invalid area that cannot be used as a lens. Thus, the more the deviation or the invalid area is increased compared to the shape of the parabolic lens, the more the distortion is caused. It becomes hard to use as a liquid crystal field lens because it becomes large.

On the contrary, as shown in FIG. 16A, when the 9-view liquid crystal field lens is implemented with four electrodes and a buffer layer, the first to third electrodes, which are gradually widened from top to bottom, are formed on the lower plate side, and the opposite substrate is formed. When the fourth electrode formed entirely on the side is formed, as shown in Fig. 16B, a lens profile can be obtained that is close to the parabolic lens except for the vicinity of the third electrode.

In this case, about 1.8 V was applied to the first electrode, about 2 V to the second electrode, and 4 V to the third electrode, and the widths of the first to third electrodes were set to 730 μm, 230 μm, and 10 μm, respectively. It was. In this case, a first insulating film is interposed between the first electrode and the second electrode, a second insulating film is interposed between the second electrode and the third electrode, and a buffer layer is further provided on the third insulating film. The thicknesses of the insulating films and the buffer layers were in the order of 0.2 m, 0.2 m and 2 m, in turn.

The third electrode is formed using a light shielding metal, and particularly, to selectively cover a portion having a high crosstalk, and thus the upper portion of the third electrode is not used as a lens having a bend.

In the nine-view four-electrode structure, the sag is also increased in proportion to the pitch because the pitch of the lens region is large, and the liquid crystal layer is sufficiently thick (equivalent to about 50 µm) to form a liquid crystal field lens. .

The liquid crystal field lens according to the second exemplary embodiment of the present invention having the buffer layer and the four electrodes may implement a stable profile in a shape substantially similar to that of the parabolic lens, as shown in FIG. 16B. It is useful for a large area display device displayed in a multi-view such as a view.

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.

1 is a cross-sectional view showing a conventional liquid crystal field lens

FIG. 2 is a diagram illustrating potential distribution after voltage application when forming the liquid crystal field lens of FIG. 1; FIG.

3 is a cross-sectional view of a stereoscopic display device using a liquid crystal field lens according to a first exemplary embodiment of the present invention.

4 is a cross-sectional view illustrating a liquid crystal field lens of FIG. 3.

FIG. 5 is a graph showing a potential distribution and a liquid crystal molecular array distribution when a voltage is applied to the structure of FIG. 4; FIG.

6 is a graph illustrating phases according to positions of liquid crystal field lenses obtained through FIGS. 4 and 5.

7 is a cross-sectional view of a stereoscopic display device using a liquid crystal field lens according to a second exemplary embodiment of the present invention.

8 is a plan view illustrating a pixel array corresponding to the liquid crystal field lens of FIG. 7.

9 is a plan view showing an electrode on a second substrate of a liquid crystal field lens;

10 is a plan view showing an electrode on a first substrate of a liquid crystal field lens;

FIG. 11 is a cross-sectional view illustrating the liquid crystal field lens of FIG. 7. FIG.

12 is a perspective view illustrating the liquid crystal field lens of FIG. 7.

13 is a lenticular simulation diagram of a liquid crystal field lens having three electrodes without a buffer layer.

14 is a lenticular simulation diagram of a liquid crystal field lens with four electrodes of the present invention.

15A and 15B are simulation views showing an arrangement structure and a lens shape thereof when the 9-view liquid crystal field lens is implemented with three electrodes without a buffer layer.

16A and 16B are simulation diagrams showing an arrangement structure and a lens shape when a 9-view liquid crystal field lens is implemented with four electrodes and a buffer layer.

* Description of the symbols for the main parts of the drawings *

100: first substrate 101: first electrode

102 insulating film 103 second electrode

104: buffer layer 200: second substrate

201: third electrode 300: liquid crystal layer

350: display panel 400: first substrate

401: first electrode 402: first insulating film

403: second electrode 404: second insulating film

405: third electrode 406: first alignment layer

500: second substrate 501: fourth electrode

502: second alignment layer 600: liquid crystal layer

700: light source 1000, 10000: liquid crystal field lens

Claims (19)

First and second substrates in which a plurality of lens regions are defined correspondingly and disposed to face each other; A first electrode formed between the centers of adjacent left and right lens regions with respect to each of the lens regions on the first substrate; A first insulating film formed on the first substrate including the first electrode; A second electrode formed on the first insulating layer corresponding to an edge portion of each lens region; A buffer layer formed on the first insulating film including the second electrode; A third electrode formed entirely on the second substrate; And And a liquid crystal layer filled between the first substrate and the second substrate. The method of claim 1, The buffer layer is a photo acrylic or BCB (Benzene CycloButene) characterized in that the liquid crystal field lens. The method of claim 1, And a dielectric constant of the buffer layer is smaller than that of the liquid crystal layer. The method of claim 1, The buffer layer is a liquid crystal field lens, characterized in that having a thickness of 1 ~ 10㎛. The method of claim 1, And the first electrode is formed symmetrically with respect to the left and right adjacent lens regions bordering the second electrode. The method of claim 1, And first and second alignment layers are further formed on the buffer layer and the third electrode, respectively. The method of claim 6, And the first alignment layer is rubbed in a longitudinal direction of the second electrode, and the second alignment layer is rubbed in a direction crossing the rubbing direction of the first alignment layer. The method of claim 1, And the first and third electrodes are transparent metals. The method of claim 8, The second electrode is a light shielding metal, characterized in that the liquid crystal field lens. The method of claim 1, When driving the liquid crystal layer AC voltage having a peak value of 1.6 to 2V is applied to the first electrode, AC voltage having a peak value of 2.5 to 15V is applied to the second electrode, and the third electrode is grounded. Electric field lens. The method of claim 1, And a fourth electrode formed on the entire surface of the first substrate via a second insulating film between the layers between the first substrate and the first insulating film including the first electrode. First and second substrates in which a plurality of lens regions are defined correspondingly and disposed to face each other; A first electrode formed on the entire surface of the first substrate; A first insulating film formed on the first substrate including the first electrode; A second electrode formed on the first insulating layer between the centers of adjacent left and right lens regions with respect to each lens region; A second insulating film formed on the first insulating film including the second electrode; A third electrode formed on the second insulating layer corresponding to an edge portion of each lens region; A fourth electrode formed on the entire surface of the second substrate; And And a liquid crystal layer filled between the first substrate and the second substrate. The method of claim 12, A first and a second alignment layer are further formed on the second insulating film and the fourth electrode including the third electrode, respectively. The method of claim 13, And the first alignment layer is rubbed in a longitudinal direction of the second electrode, and the second alignment layer is rubbed in a direction crossing the rubbing direction of the first alignment layer. The method of claim 12, The first, the second electrode and the fourth electrode is a liquid crystal field lens, characterized in that made of a transparent metal. The method of claim 15, The third electrode is a liquid crystal field lens, characterized in that made of a light shielding metal. The method of claim 12, The overcoating layer is further formed on the second insulating layer including the third electrode. The method of claim 12, When driving the liquid crystal layer An AC voltage of 0 to 1.6 V is applied to the first electrode, an AC voltage having a peak value of 1.6 to 2 V is applied to the second electrode, and an AC voltage having a peak value of 2.5 to 10 V to the third electrode. Is applied, and the fourth electrode is grounded. A liquid crystal field lens according to any one of claims 1 to 18, And a display panel configured to emit two-dimensional first and second images under the liquid crystal field lens.

Images