KR20060032035A - Display device with filter pannel for regulation of viewing angle - Google Patents

Abstract

The present invention relates to a display device having a filter panel for controlling the viewing angle, and in particular, comprising a first panel for realizing a character or an image and a second panel for controlling the viewing angle of the first panel. It relates to a display device.

The second panel is composed of two substrates formed of transparent glass or resin layers facing each other, a liquid crystal layer formed between the two substrates, and a plurality of electrodes formed on the two substrates to apply an electric field to the liquid crystal layer. It is a filter panel for viewing angle control, characterized in that for controlling the light transmittance of the liquid crystal material by the voltage applied to the plurality of electrodes.

First panel, second panel, liquid crystal display, flat panel display, viewing angle

Description

DISPLAY DEVICE WITH FILTER PANNEL FOR REGULATION OF VIEWING ANGLE}

1 is a view showing a conventional liquid crystal display device.

2A and 2B show a liquid crystal material having a particular orientation when an electric field is formed.

3A is a diagram illustrating a configuration of a display device according to the present invention.

3b shows a second panel according to the invention;

3C is a cross-sectional view taken along plane II ′ of FIG. 3B.

4A illustrates another second panel of the present invention.

4B is a cross-sectional view of another second panel of the present invention.

*** Description of the symbols in the drawings ***

350: first panel 370, 470: second panel

330: first liquid crystal layer 385, 485: second liquid crystal layer

The present invention relates to a display device, and more particularly, to a display device capable of controlling a viewing angle by providing a filter panel.

Recently, with the development of various portable electronic devices such as mobile phones, PDAs, and notebook computers, there is an increasing demand for flat panel display devices for light and thin applications. Such flat panel displays are being actively researched, such as LCD (Liquid Crystal Display), PDP (Plasma Display Panel), FED (Field Emission Display), and VFD (Vacuum Fluorescent Display). Liquid crystal displays (LCDs) are in the spotlight for reasons of implementation.

The liquid crystal display device is a typical transmissive display device, and is a flat panel display device that displays a desired image on a screen by adjusting the amount of light passing through the liquid crystal layer by refractive index anisotropy of liquid crystal molecules. Accordingly, in the liquid crystal display device, a back light, which is a light source that passes through the liquid crystal layer, is provided to display pixels in addition to the liquid crystal panel.

FIG. 1 is an exploded perspective view schematically illustrating a configuration of a general liquid crystal display device. As shown in the drawing, the liquid crystal display device 100 may include a liquid crystal panel 150 and a backlight disposed on the rear surface of the liquid crystal panel 150. 160).

The liquid crystal panel 150 is a place where an actual image is realized, and includes a first substrate 110 and a second substrate 120 and a liquid crystal layer 130 formed therebetween.

The first substrate 110 is a thin film transistor array substrate, and a gate line 133 and a data line 132 are formed, and a plurality of subpixel regions are defined by the gate line 133 and the data line 132. do. In the region where the gate line 133 and the data line 132 cross each other, a switching element 121 for switching each subpixel is formed, and in the subpixel region a pixel electrode for driving a liquid crystal ( 123 is formed.

The second substrate 120 is a color filter substrate, and a color filter layer 103 for real color and a black matrix 139 for preventing light leakage between pixels are formed. In this case, the color filter layer 103 is formed such that color filters of R, G, and B colors are arranged in regions corresponding to the respective subpixels. The common electrode 101 for driving the liquid crystal is formed on the color filter layer 103 together with the pixel electrode 123.

Although not shown in the drawings, the backlight 160 may include a lamp that generates light, a reflector that reflects light emitted from the lamp to improve light efficiency, and uniformly incident light emitted by the lamp into a liquid crystal panel. It consists of an optical sheet to irradiate light to the liquid crystal panel 150.

In addition, upper and lower polarizing plates 140a and 140b are formed on upper and lower portions of the liquid crystal panel 150 to polarize light coming from the backlight.

Meanwhile, liquid crystal molecules of the liquid crystal layer 130 are oriented in a predetermined direction between opposing surfaces of the first and second substrates 110 and 120. In this case, the liquid crystal layer 130 is aligned when an electric field is formed between the pixel electrode 123 formed for each unit pixel of the first substrate 110 and the common electrode 101 formed on the entire surface of the second substrate 120. By changing the direction, light is passed or blocked for each unit pixel to display characters or images.

As described above, such a liquid crystal display device has attracted attention as a representative flat panel display device, and improvements and developments in various fields are in progress. Technical research on the viewing angle of the liquid crystal display device has been considered as one of the most important tasks for such a multifaceted approach, and the approach has been actively progressed toward the widest viewing angle of the liquid crystal display device.

However, when such a wide viewing angle flat panel display is applied to a monitor of various electronic equipment, the viewing angle characteristic does not always work as an advantage. In other words, when protecting information from others is very important, such as when using a laptop or desktop computer to perform confidential documents or security-critical operations, or withdrawing cash from an automated teller machine, A wide viewing angle may rather cause a very serious problem of information leakage. As a result, the wide viewing angle of the flat panel display device is an advantage as a display device, but at the same time there is a problem that can act as a disadvantage.

Accordingly, an object of the present invention is to provide a display device having a filter panel for controlling a viewing angle of the display device in an upper region of a conventional display device.

The display device of the present invention for achieving the above object is basically mounted on the first panel and the upper part of the first panel for the implementation of characters or images, to control the viewing angle of the first panel by the electrical switching operation It is comprised including the 2nd panel which is a filter panel.                     

The first panel may be formed of one of a flat panel display panel such as a liquid crystal display panel (LCD), a field emission display panel (FED), a plasma display panel (PDP), or a cathode ray tube (CRT). When the first panel is a liquid crystal display panel, the first panel includes a first substrate having a thin film transistor array, a second substrate having a color filter, and a first liquid crystal layer interposed between the first substrate and the second substrate.

The second panel comprises a third substrate and a fourth substrate facing each other made of a transparent glass or resin layer; A third electrode formed on the third substrate; A fourth electrode formed on the fourth substrate; And a second liquid crystal layer formed between the third substrate and the fourth substrate, wherein the second liquid crystal layer is a filter panel driven by a voltage applied to the third electrode and the fourth electrode.

In this case, the third electrode formed on the third substrate and the fourth electrode formed on the fourth substrate are each formed in a comb type, and between the teeth of a comb-shaped electrodes of the third electrode. The comb-shaped electrodes of the fourth electrode are alternately arranged in the space to form an electric field.

In addition, the second panel of the present invention comprises a third substrate and a fourth substrate facing each other made of a glass or resin layer; A third electrode and a fifth electrode formed on the third substrate; A fourth electrode and a sixth electrode formed on the fourth substrate; It consists of a 2nd liquid crystal layer formed between the said 3rd board | substrate and a 4th board | substrate.

At this time, the third electrode and the fifth electrode formed on the third substrate are each formed in a comb type, and the comb-shaped electrodes of the third electrode and the fifth electrode are formed to face each other alternately. Similarly, the fourth electrode and the sixth electrode formed on the fourth substrate are also formed in a comb type, and the comb-shaped electrodes of the fourth electrode and the sixth electrode are formed to be alternately disposed to face each other.

Here, the third electrode formed on the third substrate and the sixth electrode formed on the fourth substrate are formed of the same material and electrically connected to each other, and the fourth electrode and the third substrate formed on the fourth substrate The fifth electrode to be formed is also formed of the same material and electrically connected.

In summary, the second panel is configured in the form of a simple liquid crystal panel in which a liquid crystal material is inserted between two transparent substrates on which electrodes are formed, and includes a third electrode, a fifth electrode, a fourth electrode, and a fourth electrode formed on the two substrates. By the arrangement structure of 6 electrodes, the electric field which produces the liquid crystal orientation of various directions is formed. As a result, the directions of the long axis and the short axis of the liquid crystal molecules change according to the direction of the electric field generated between the third electrode and the fourth electrode, the fifth electrode, and the sixth electrode, and as a result, the birefringence rate according to the viewing angle direction of the observer. As a result, the light transmittance changes to control the viewing angle.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2A and 2B illustrate a basic concept of the present invention, in which different electrodes 201 and 223 having an electric field are formed on upper and lower substrates 220 and 210, respectively, and the upper and lower substrates 220 are shown. And a partial cross section of the liquid crystal panel 250 having the liquid crystal layers 230 and 230 ′ formed therebetween.

First, as shown in FIG. 2A, when no voltage is applied to the electrodes 201 and 203, the liquid crystal material constituting the liquid crystal layer 230 is basically perpendicular to the upper and lower substrate surfaces 220 and 210. It has a homeotropic molecular orientation arranged in the above, and transmits the light incident to the lower portion of the liquid crystal panel in the first direction (1).

On the other hand, FIG. 2B illustrates a case where an electric field is formed by applying voltages on the different electrodes 201 and 223, and the liquid crystal material of the liquid crystal layer 230 ′ is aligned with molecules along the direction of the electric field. Will change state.

As shown in the figure, the liquid crystal material rotates according to the direction of the electric field formed between the two different electrodes 201 and 223, and the incident angle of light in the state in which the long and short axes of the liquid crystal molecules are rotated left or right. The birefringence is changed in accordance with this, and the amount of light transmitted is controlled, whereby the brightness on the screen changes in accordance with the viewing angle.

That is, when looking at the liquid crystal panel 250 of FIG. 2B in the direction of the third arrow 3, the observer can sense the light that has been refracted along the liquid crystal material and passed through, but the first arrow 1 or the second When the liquid crystal panel 250 is observed in the direction of the arrow 2, the screen appears dark due to a decrease in light transmittance caused by a change in birefringence.

As a result, the second panel of the present invention uses the viewing angle dependency principle, which is a typical characteristic of the liquid crystal material, and mounts a liquid crystal panel for controlling the viewing angle, that is, a filter panel, on the top of the conventional display device to view the panel. The luminance of the display device is inverted by adjusting the light transmittance of the liquid crystal material according to the viewing angle.

Hereinafter, a display device employing a filter panel according to the present invention will be described with reference to the drawings.                     

3 is a perspective view schematically illustrating a display device of the present invention, and illustrates an example in which a general liquid crystal display panel is applied to a first panel.

Practically, the present invention is not only applied to flat panel display panels such as liquid crystal display panels. Since the filter panel of the present invention is positioned in front of the display panel to adjust the viewing angle by adjusting the transmittance of light emitted from the display panel, the filter panel may be usefully applied not only to a flat panel display device but also to a conventional display device such as a cathode ray tube (CRT). Could be. However, the following description will be limited to the liquid crystal display panel for convenience.

As shown in the figure, the display device 300 of the present invention includes a first panel 350 that embodies text and images, and a rear panel of the first panel 350. A backlight 360 for irradiating light with the light, and an upper and lower polarizers (not shown) positioned above and below the first panel 350 to polarize the light, and above the first panel 350. The second panel 370 is a filter panel that controls the viewing angle of the flat panel display 300.

The first panel 350 is an actual image, and includes a first liquid crystal layer 330 formed between the first substrate 310 and the second substrate 320 facing each other.

Although not shown in the drawing, the first substrate 310 is a thin film transistor array substrate, and the gate lines and the data lines are vertically intersected, and the plurality of sub-pixel regions are defined by the gate lines and the data lines. A thin film transistor for switching each subpixel is formed in an area where the gate line and the data line intersect, and a first electrode for driving the liquid crystal is formed in the subpixel area.

The second substrate 320 is a color filter substrate, and a color filter layer for realizing color and a black matrix for preventing light leakage between pixels are formed. In this case, the color filter layer is formed such that color filters of R, G, and B colors are disposed in regions corresponding to each subpixel. A second electrode for driving the liquid crystal is formed on the color filter layer together with the pixel electrode on the first substrate.

The second electrode may be formed on the first substrate together with the first electrode to form a transverse electric field.

On the opposing surfaces of the first and second substrates 310 and 320, the liquid crystal material of the first liquid crystal layer 330 is arranged to have a constant orientation. In this case, the liquid crystal material is rotated by dielectric anisotropy when an electric field is formed between the first electrode and the second electrode, thereby changing the transmittance of light for each unit pixel to display characters or images.

In addition, a driving circuit unit (not shown) is provided on a side surface of the first substrate 310 to apply a signal to the thin film transistor, the first electrode, and the second electrode for driving the pixel, respectively, and the first substrate 310 The backlight 360 positioned at the bottom of the back panel irradiates light to the first panel 350.

The second panel 370 is disposed above the first panel 350, and is disposed between the third and fourth substrates 380 and 390, and the third and fourth substrates 380 and 390. The second liquid crystal layer 385 is inserted. In this case, the second panel 370 is formed separately from the first panel 350, is controlled, and formed to be detached and attached to the first panel 350 as necessary.

FIG. 3B is an enlarged perspective view of the second panel 370 of FIG. 3A. As shown in the drawing, the second panel 370 of the present invention has a structure similar to a simple liquid crystal panel.

First, transparent conductors, such as indium-tin-oxide (ITO) or indium-zinc-oxide (IZO), are formed on the third and fourth substrates 380 and 390 formed of a resin layer made of glass or transparent material, respectively. The third electrode 383 and the fourth electrode 393 are formed in a comb type having a plurality of teeth of a comb.

In this case, the comb-shaped electrodes of the fourth electrode 393 are alternately formed to alternate with the comb-shaped electrodes of the third electrode 383, and the fourth electrode 393 formed on the fourth substrate 390 is provided. Is to be projected on the third substrate 383 to have the same position as the dotted line 393 'in the drawing.

On the other hand, the switch for turning on / off the second panel of the present invention may be a manual switch or may be an automatic switch turned on / off by a switching signal output from the control device.

If the second panel according to the present invention employs a manual switch that is electrically switched by hand, by adjusting the voltage level manually, the degree of rotation of the liquid crystal material is adjusted, whereby the viewing angle of the display device may be arbitrarily adjusted as necessary. Can be configured to control.                     

Once the voltage is applied to the third electrode 383 and the fourth electrode 393, the liquid crystal molecules of the liquid crystal layer 385 are formed in the substrate in the direction of the electric field generated by the two electrodes 383 and 393. In this case, the alignment state of the liquid crystal molecules and the light transmittance thereof change accordingly, and the color or brightness of the screen changes according to the viewing angle of the second panel.

On the other hand, when the voltage is off, the liquid crystal molecules of the second liquid crystal layer 385 are oriented perpendicular to the third and fourth substrates 383 and 393, and are incident from the lower portion of the second panel 370. All of the light is transmitted in a direction perpendicular to the second panel.

As a result, the second panel according to the present invention controls the viewing angle of the display device by applying the viewing angle dependence of the liquid crystal display device, that is, the characteristic in which the color or the brightness changes depending on the viewing direction or angle.

FIG. 3C illustrates a portion of a cross section of the II ′ plane of FIG. 3B, as shown in the figure, formed on the third electrode 383 and the fourth substrate 390 formed on the third substrate 380. The fourth electrodes 393 are alternately arranged with the second liquid crystal layer 385 interposed therebetween to generate an electric field.

The second liquid crystal layer 385 is aligned as shown in the drawing along the direction of the electric field generated between the third electrode 383 and the fourth electrode 393, so that the two liquid crystal regions having different alignments ( a, b) has a shape such that it is repeatedly arranged over the entire substrate area of the second panel 370.

As a result, the liquid crystal molecules in the first liquid crystal region a significantly reduce the light transmittance in the first direction 10, whereby an observer observes the second panel 370 in the first direction 10. In this case, the first liquid crystal region a appears as black stripes having a predetermined width so that the entire screen of the display device repeatedly shows black stripes.

Similarly, when the viewer looks at the second panel 370 in the second direction 20, the light transmittance is significantly reduced by the liquid crystal material of the second liquid crystal region b, and thus the second liquid crystal region on the screen. (b) is shown as black stripes having a predetermined width.

As a result, the display device according to the present invention repeatedly displays black stripes on the screen at both the left and right viewing angles, and as a result, the screen information cannot be viewed at other angles than the front.

4A and 4B show another embodiment of the present invention, in which modification is made to the electrode structure constituting the second panel of the present invention.

The present embodiment alternately forms different electrode pairs for generating an electric field on each of the third substrate 480 and the fourth substrate 490.

First, FIG. 4A illustrates a portion of a third substrate 480 on which a third electrode 483 and a fifth electrode 493 'are formed, and the third electrode 483 and the fifth electrode 493' are formed. Each comb is shaped like a comb, and arranged alternately.

Although not shown in the drawing, the fourth electrode and the sixth electrode are alternately disposed on the fourth substrate, and the two dotted lines 493 and 483 'shown in FIG. 4A are formed on the fourth electrode 493 on the fourth substrate. ) And a sixth electrode 483 'are shown when the third electrode 480 is projected onto the third substrate 480.

At this time, as shown in the figure, the third electrode 483 and the fifth electrode 493 'on the third substrate 480 and the fourth electrode 493 and the sixth electrode 483' on the fourth substrate are Alternately disposed over the entire area of the second panel 470, where a third electrode 483 formed on the third substrate 480 and a sixth electrode 483 formed on the fourth substrate (not shown) are provided. ') Is formed of the same material and is electrically connected. The fourth electrode 493 of the third substrate 480 and the fifth electrode 493' formed on the fourth substrate (not shown) are also made of the same material. It is formed and electrically connected.

FIG. 4B is a cross-sectional view of the second panel 470 shown in FIG. 4A. As shown in the drawing, the third electrode 483 and the fourth electrode 493 and the fifth electrode 493 'and When a voltage is applied to the sixth electrode 483 ', an electric field is formed between the electrodes, so that the liquid crystal material of the second liquid crystal layer 485 has two liquid crystal regions having a vertical alignment and an inclined orientation as shown in FIG. c, d) and orient.

Here, when the observer observes the first liquid crystal region d in the first direction 10, the light incident on the second panel 470 is transmitted to detect the text and the image as it is, but in the second direction 20. In the case of observation, the light transmittance is considerably reduced to appear as black stripes. When observed in the third direction 30, the light is semi-transmissive to give a gray tone.

In addition, when the observer observes the second liquid crystal region d in the direction of the first arrow 10, the text and image information transmitted through the second panel 470 are accurately displayed, but the second direction 20 and When viewed from the third direction 30, the phenomenon that the brightness is reduced due to the transflectance of light appears, so that the information of the screen can not be seen from other angles other than the front.

As described above, the gist of the present invention is to provide a display device having a second panel for controlling the viewing angle which causes the liquid crystal material to have a specific alignment state when a voltage is applied to the liquid crystal layer, thereby blocking light in a specific direction. As the scope of the present invention is not limited to the above-described embodiment.

In other words, the scope of the present invention is to configure a plurality of liquid crystal regions by varying the arrangement of the electrode in the second panel, and thus, the second panel for viewing angle control in which the transmittance of light varies according to the viewing angle of the display device. It includes everything.

For example, the liquid crystal material of the second liquid crystal layer formed on the second panel may have a molecular orientation that is horizontally arranged with respect to the upper and lower substrates when the voltage is not applied to the electrodes. Since the rubbing directions of the substrates are formed in parallel, all the light incident perpendicularly to the second panel is transmitted, and images and images can be displayed. In addition, when an electric field is formed by applying voltages to different electrodes formed on the second panel, the liquid crystal material of the liquid crystal layer changes the alignment state of molecules along the direction of the electric field, so that the display device is desired. The viewing angle is controlled by changing the transmittance of light according to the viewing angle.

Therefore, the above specification does not limit the rights of the present invention, the scope of the rights according to the present invention will be determined by the claims to be described later.

As described above, the present invention controls the viewing angle of the display device by mounting a filter panel configured in the form of a simple liquid crystal panel on an upper portion of the display device, and adjusting the light transmittance of the liquid crystal. In addition, the filter panel for controlling the viewing angle is formed to be detachable and attached to the display device as necessary, so that various information such as a cash machine or a personal computer or mobile phone that need to perform security-critical operations are important. It enables the application to the display device.

Claims (16)

A first panel for embodying text or images; And And a second panel configured to control the viewing angle of the first panel by adjusting the light transmittance by application of an electric field. The method of claim 1, wherein the first panel, And a flat panel display panel including liquid crystal display (LCD), plasma display panel (PDP), field emission display (FED), electric luminescence (EL), and vacuum fluorescent display (VFD). The method of claim 2, wherein the LCD, A thin film transistor array substrate; Color filter substrates; A first liquid crystal layer formed between the thin film transistor array substrate and the color filter substrate; And And a LCD including a backlight for irradiating light onto the liquid crystal layer. The method of claim 1, wherein the first panel is Display device characterized in that the CRT (Cathod Ray Tube). The method of claim 1, wherein the second panel, A third substrate and a fourth substrate facing each other made of a transparent glass or resin layer; A second liquid crystal layer formed between the third substrate and the fourth substrate; And And an electrode structure for aligning liquid crystal molecules in a specific direction by applying an electric field to the second liquid crystal layer. The method of claim 5, wherein the electrode structure, A third electrode formed on the third substrate; And And a fourth electrode formed on the fourth substrate. The display device of claim 6, wherein the third electrode and the fourth electrode are alternately formed on a substrate to generate an electric field. The method of claim 5, wherein the electrode structure, Third and fifth electrodes formed on the third substrate; And It is formed including a fourth electrode and a sixth electrode formed on the fourth substrate, And the third and sixth electrodes and the fourth and fifth electrodes are alternately formed on a substrate to generate an electric field. The display device of claim 5, wherein the second panel is formed and controlled separately from the first panel. The display device of claim 5, wherein the second panel is detachable from and attached to the display device.  The display device according to claim 5, wherein the second panel is operated by a manual switch which is turned on / off by hand. The display device of claim 5, wherein the manual switch adjusts the strength of the electric field by hand. The display device of claim 5, wherein the second panel is operated by an automatic switch turned on / off by a switching signal output from a control device. The display device of claim 5, wherein the liquid crystal material of the second liquid crystal layer is vertically aligned with respect to the third and fourth substrates when no electric field is applied. The display device of claim 5, wherein the liquid crystal material of the second liquid crystal layer is horizontally aligned with respect to the third and fourth substrates when no electric field is applied. The display device of claim 15, wherein the third substrate and the fourth substrate are rubbed in parallel.

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