WO2009131410A2

WO2009131410A2 - Display device driven by electric field

Info

Publication number: WO2009131410A2
Application number: PCT/KR2009/002157
Authority: WO
Inventors: Dae-Jung Jeong; Yi-Yong Kim; Byung-Uk Kim; Chun-Hyuk Lee
Original assignee: Dongjin Semichem Co., Ltd.
Priority date: 2008-04-25
Filing date: 2009-04-24
Publication date: 2009-10-29
Also published as: TW200947392A; WO2009131410A3; KR20090112907A

Abstract

The present invention relates an electric field driving display device (10) for easily displaying the grays includes: a first substrate (110); a plurality of first electrodes (191 ) formed on the first substrate; a partition having a plurality of switch holes and formed on the first electrode; and a plurality of driving bodies (370) disposed one by one in each of the switch holes, wherein the electric field driving display device is divided into gray regions including at least one of the switch holes and pixel regions including a plurality of gray regions, and drives the driving body as a unit of the gray region, thereby displaying a gray. In the electric field driving display device according to the present invention, one pixel region is divided into three gray regions for driving such that a total of four grays may be realized.

Description

[SPECIFICATION] [Invention Title]

DISPLAY DEVICE DRIVEN BY ELECTRIC FIELD [Technical Field] The present invention relates to a display device. More particularly, the present invention relates to a display device driven by an electric field. [Background Art]

Among flat panel displays that are extensively used, there are a liquid crystal display, a plasma display panel, and an organic light emitting display. The LCD is a display device using electro-optical characteristics of liquid crystals in which light transmission amounts are varied according to an applied electric field to thereby realize the display of images, but the viewing angle thereof is narrow and the cost is high. The PDP is a display device for displaying images by using plasma generated by gas discharge, but high heat is unavoidably generated in the panel by the high temperature discharge gas. In the OLED, electrons and holes are injected into an organic illumination layer respectively from a cathode (the electron injection electrode) and an anode (the hole injection electrode). The injected electrons and holes are combined to generate excitons, which illuminate when converting from an excited state to a ground state. In such an OLED, only a portion of the injected electric charge causes illumination and the rest is lost as heat.

In addition, a field emission display (FED) utilizing the tunneling effect of quantum mechanics to emit electrons from electron emission sources formed on cathode electrodes may be provided. The emitted electrons strike a phosphor layer formed on an anode electrode to illuminate the phosphor layer and thereby result in the display of images. An electrophoretic display (EPD) is a display device utilizing the electrophoretic phenomenon to repeatedly write or erase information of symbols such as characters and numbers. A display device driven by an electric filed uses gravity force and an electric force to control the position of a driving body such that the transmittance of incident light is controlled, thereby displaying the wanted images. Here, in the display device driven by the electric field, it is difficult to control the middle position of the driving body such that the display of grays is difficult.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. [DETAILED DESCRIPTION] [Technical Problem]

The present invention easily displays grays in an electric field driving display device. [Technical Solution]

The technical object of the present invention is not limited by the above- described technical object, and other technical objects not described above may be clearly understood by a person of ordinary skill in the art based on the following description. An electric field driving display device according to an exemplary embodiment of the present invention includes: a first substrate; a plurality of first electrodes formed on the first substrate; a partition having a plurality of switch holes and formed on the first electrode; and a plurality of driving bodies disposed one by one in each of the switch holes, wherein the electric field driving display device is divided into gray regions including at least one of the switch holes and pixel regions including a plurality of gray regions, and drives the driving body as a unit of the gray region, thereby displaying a gray.

A second substrate disposed on the partition and a second electrode formed on the second substrate may be further included. Color filters of red, green, and blue formed on the second substrate may be further included, wherein the color filters may have different colors per pixel region. The gray region may have a first region, a second region, and a third region. There may be 48 switch holes for each pixel region.

Each switch hole may include a fixing groove and a driving groove, the first electrode may be exposed through the fixing groove, and the second electrode may be exposed through the driving groove.

The area of a cross-section of the driving groove may be increased moving away from the first substrate. The second electrode may be disposed on the edge of the cross-section of the driving groove. The driving body may have a spherical shape.

The diameter of the driving body may be equal to or more than the width of the fixing groove.

The position of the driving body may be determined by the voltage applied to the first electrode and the second electrode. A backlight unit supplying light toward the first substrate for display may be further included, wherein the backlight unit may have a condenser lens condensing the light toward the driving groove.

In the electric field driving display device according to the present invention, one pixel region is divided into three gray regions for driving such that a total of four grays may be realized.

[Advantageous Effects]

In the electric field driving display device according to the present invention, one pixel region is divided into three gray regions for driving such that a total of four grays may be realized. [Brief Description of the Drawings]

FIG. 1 is a top plan view of an electric field driving display device according to an exemplary embodiment of the present invention.

FIG. 2 is a cross-sectional view of the electric field driving display device of FIG. 1 taken along the line H-II. FIG. 3A to FIG. 3D are top plan views showing gray steps of an electric field driving display device according to an exemplary embodiment of the present invention. FIG. 4 is a cross-sectional view explaining driving of one gray of an electric field driving display device according to an exemplary embodiment of the present invention. [Best Mode] Details of the exemplary embodiment are included in the detailed description and the drawings.

These advantages and features of the present invention, and methods of achieving the same, will become apparent and more readily appreciated from the following description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to exemplary embodiments to be disclosed below, and may be implemented in various forms. It will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the general inventive concept, the scope of which is defined in the appended claims and their equivalents.

Hereinbelow, an electric field driving display device according to an exemplary embodiment of the present invention will be described with reference to FIG. 1 and FIG. 2.

FIG. 1 is a top plan view of an electric field driving display device according to an exemplary embodiment of the present invention, and FIG. 2 is a cross-sectional view of the electric field driving display device of FIG. 1 taken along the line II- II.

Referring to FIG. 1 and FIG. 2, an electric field driving display device 10 includes a display panel 100 and a backlight unit 400.

The display panel 100 includes a lower substrate 110 formed with a first electrode 191 as a portion displaying images by controlling the amount of light, an upper substrate 210 formed with a second electrode 270, a fixing partition 310 having a fixing groove 315, a driving partition 330 having a driving groove 335, a light reflector 350 disposed between the fixing partition 310 and the driving partition 330, and a driving body 370 disposed in the driving groove 335. The first electrodes 191 extending in one direction are arranged parallel to each other on the transparent lower substrate 110 that is made of glass or the like. Each first electrode 191 may be made of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The first electrode 191 has a quadrangular shape and may be disposed corresponding to each driving groove 335. • In addition, a switching device 130 for individually switching a voltage that is applied to each first electrode 191 is formed on the lower substrate 110, and the switching device 130 is connected to the first electrode 191. As the switching device 130, a thin film transistor may be used, and in this case, a gate line (not shown) that transfers a scanning signal for switching the thin film transistor and a data line (not shown) that transfers a gray voltage applied to the first electrode 191 may be formed on the lower substrate 110 while crossing each other. The thin film transistor may include a gate electrode, a source electrode, a drain electrode, and a semiconductor. The first electrode 191 is extended such that the number of switching elements 130 may be reduced. A light blocking member 120 is formed on the lower substrate 110, and the light blocking member 120 is disposed on a portion where the first electrode 191 is not formed on the lower substrate 110. That is, the light blocking member 120 does not overlap the first electrode 191. However, a portion of the end of the light blocking member 120 may overlap the first electrode 191. The light blocking member 120 prevents a mixture of light between neighboring pixels.

The fixing partition 310 having the fixing groove 315 is formed in the light blocking member 120. A photosensitive material may be coated, exposed, and developed to form the fixing partition 310. The fixing partition 310 may be made of an opaque material through which light is not transmitted. When the fixing partition 310 is made of a black color material, deterioration of display quality by transmittance of unnecessary light on the fixing partition 310 or reflection by the fixing partition 310 may be prevented. When the fixing partition 310 has the function of the light blocking member 120, the light blocking member 120 may be omitted. The fixing groove 315 has a function of fixing the driving body 370. The first electrode 191 is exposed through the fixing groove 315.

The light reflector 350 is formed on the fixing partition 310. The light reflector 350 has a function of guiding diffused light into the display region of the upper substrate 210.

The driving partition 330 having the driving groove 335 is formed on the light reflector 350. The cross-section of the driving groove 335 has a circular shape, and the area of the cross-section is increased from the lower substrate 110 to the upper substrate 210. That is, the driving groove 335 has a truncated circular cone shape. The cross- section of the driving groove 335 may have a quadrangular shape, and the driving groove 335 has a quadrangular pyramid column shape that is overturned. The driving partition 330 may be made of a dry photosensitive material having good transmittance.

The driving body 370 has a spherical shape and is disposed in the driving groove 335, and the position thereof is determined by electrical force. The driving body 370 has positive or negative charges. The driving body 370 may be made of a multi-layered structure. For example, the outside of the driving body 370 may be made of an organic layer for maintaining the charges, and the inside thereof may be made of a metal layer for total reflection of light. In additional, the driving body 370 may be made of the opaque material so as to not reflect light.

The diameter d of the driving body 370 is the same as the width w of the fixing groove 315 or is larger than the width of the fixing groove 315. Accordingly, the driving body 370 may be freely moved in the space of the driving groove 335, but may not be completely inserted into the space of the fixing groove 315. If the driving body 370 is inserted between the light reflector 350 and/or the fixing groove 315 by the attraction force along with the first electrode 191, and thereby closes the fixing groove 315, the light emitted from the backlight unit 400 is blocked such that a black state may be realized.

In the present exemplary embodiment, the driving body 370 is not completely inserted in the fixing groove 315 such that the driving body 370 may not contact the first electrode 191. Therefore, an insulating layer for protecting the first electrode 191 may be omitted. An inert gas (not shown) such as argon, neon, or helium is injected into the driving groove 335 containing the driving body 370. Instead of an inert gas, a different gas that is appropriate for storage of charges of the driving body 370 such as nitrogen or dry air may be filled therein. Also, the driving groove 335 may be maintained in a vacuum state. The upper substrate 210 is combined with the driving partition 330. Color filters 230 of red, green, and blue are formed on the upper substrate 210, and an insulating layer 250 for protecting the color filters 230 is formed thereon. Also, the second electrode 270 is formed on the insulating layer 250. The second electrode 270 may be made of a transparent conductor such as ITO or IZO. The insulating layer 250 and the second electrode 270 are exposed through the driving groove 335. Also, the second electrode 270 is disposed on the edge of the driving groove 335. In more detail, when the driving body 370 contacts the insulating layer 250, the second electrode 270 is positioned between the contact portion and the circumference of the driving partition 330 defining the driving groove 335. Accordingly, the driving body 370 does not directly contact the second electrode 270 such that an insulating layer for protecting the second electrode 270 on the second electrode 270 may be omitted.

The backlight unit 400 provides light to the display panel 100 and includes a lamp 420, a light guide plate 410 that converts light emitted from that the lamp 420 that is a linear or dot light source into surface light, and a condenser lens 430 that collects light emitted from the light guide plate 410 and provides it to the fixing groove 315 and the driving groove 335 that is a display region. As the lamp 420, a linear light source such as a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), and the like, or a dot light source such as a light emitting diode (LED) and the like may be used. In addition, a surface light source may be used, and in this case, the light guide plate 410 may be omitted. Further, the condenser lens 430 may be directly formed on the surface of the light guide plate 410 or in a single layer, or in a separate film form or a single layer form on a side of the display panel 100.

The backlight unit 400 may be disposed on either one of the lower substrate 110 and the upper substrate 210.

This display device that is driven by an electric field changes the position of the driving body 370 in the driving groove 335 by applying an electric force and/or gravity force thereto, and displays a desired image by controlling the transmittance of the light provided from the backlight unit 400 in this way. Next, a method for displaying grays in the electric field driving display device 10 according to an exemplary embodiment of the present invention will be described with reference to FIG. 3 A to FIG. 3D.

One pixel region includes 48 switch holes each connected with a driving groove 335 and a fixing groove 315, a driving body 370 is formed in each switch hole, and the driving bodies 370 in the switch holes are driven by dividing them into three gray regions of 16 switch holes, that is, A, B, and C regions.

In FIG. 3 A, all driving bodies 370 of the A, B, and C regions block the fixing grooves 315 such that the light is not transmitted, thereby representing full black.

In FIG. 3B, the driving bodies 370 of the B and C regions close the fixing grooves 315, and the driving bodies 370 of the A region do not close the fixing grooves 315. Accordingly, the light is not transmitted in the B and C regions and the light is transmitted in the A region, thereby representing the first gray.

In FIG. 3 C, the driving bodies 370 of the C region close the fixing grooves 315, and the driving bodies 370 of the A and B regions do not close the fixing grooves 315. Accordingly, the light is not transmitted in the C region and the light is transmitted in the A and B regions, thereby representing the second gray.

In FIG. 3 A, none of the driving bodies 370 of the A, B, and C regions close the fixing grooves 315 such that the light is transmitted at all fixing grooves 315, thereby representing full white. Therefore, the driving bodies 370 are driven by dividing them into three regions in one pixel such that four grays of full black, a first gray, a second gray, and full white may be realized.

Here, the number of switch holes disposed in one pixel region may be more or less than 48, and one pixel region may be driven by dividing it into a different number of gray regions than three. For example, 50 switch holes may be formed in each pixel region, and the switch holes may be grouped by tens to provide five gray regions. In this case, seven grays may be realized.

Next, driving of the electric field driving display device 10 of the above- described structure will be described with reference to FIG. 4. FIG. 4 shows a cross- sectional view of FIG. 3 C that is the second gray. In general, a display screen of a display device is formed almost perpendicular to the horizontal plane. Therefore, the circumference of the driving groove 335 that is partitioned by the driving partition 330 forms a sloped surface with respect to the horizontal plane. The driving body 370 rolls down the sloped surface due to gravity when no voltage is applied. However, when a voltage is applied between the first electrode 191 and the second electrode 270, an electric field is formed therebetween so that the charged driving body 370 overcomes gravity and rolls up the sloped surface by electrical force. The electrical force applied to the driving body 370 is controlled by controlling the voltage generated between the first electrode 191 and the second electrode 270 such that the position of the driving body 370 may be controlled. For this purpose, the sloped surface of the driving groove 335 may have a constant inclination as shown in FIG. 4, or the inclination of the sloped surface may be gradually increased upwardly. In addition, the strength of the electrical power applied to the driving body 370 in order to overcome gravitational force is changed according to an angle of the sloped surface with reference to the horizontal plane, and accordingly, the driving voltage can be determined properly for each case.

The area of the driving groove 335 through which the light supplied from the backlight unit 400 can be passed is changed as the location of the driving body 370 changes. That is, when the driven body 370 contacts the bottom of the sloped surface, i.e., when the driven body 370 contacts the upper substrate 210, the area of the driving groove 335 through which the light can be passed is maximized, and when the driving body 370 fills completely in the fixing groove 315, the light is completely blocked. As described, the amount of light can be controlled by controlling the voltage applied between the first electrode 191 and the second electrode 270. As shown in FIG. 4, the driving body 370 is contacted with the upper substrate

210 in the regions A and B such that the light is passed through, and the driving body 370 blocks the fixing groove 315 in the region C such that the light is blocked. Accordingly, the second gray may be obtained.

Here, the driving bodies 370 of each of the gray regions A, B, and C are driven together such that one first electrode 191 may be disposed for each of the gray regions A, B, and C, and one switching element applying the voltage to the first electrode 191 may be disposed for each of the gray regions A, B, and C. One second electrode 270 may be disposed for each of the gray regions A, B, and C. The second electrode 270 may be formed as one body on the whole upper substrate 210. When the light supplied from the backlight unit 400 passes through the driving groove 335, the light may be partially scattered by the driven body 370 so that luminance can be deteriorated. In this case, the light reflector 350 induces the scattered light toward the upper substrate 210 in order to prevent the luminance deterioration. A color image can be realized by using the color filters 230. One color filter

230 is disposed for each pixel.

The size of the driving body 370 is several to several tens of micrometers such that the driven body 370 can be driven by several tens of millivolts (mV) to several volts (V) at a very high speed, and thereby the display device can be provided with fast response speed and precise control. The operation speed of the driven body 370 is proportional to the weight of the driven body 370 such that the weight thereof can be reduced by forming pores in the driving body 370.

Although the driven body 370 is driven by using gravity and electrical force in the above-described exemplary embodiment of the present invention, electrical force that is applied in the opposite direction to the existing electrical force may be used as a substitute for or to supplement the gravity force. That is, the driven body 370 can reciprocate without depending on gravity by inverting the voltage applied between the first electrode 191 and the second electrode 270.

While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

[CLAIMS] [Claim 1]

An electric field driving display device comprising: a first substrate; a plurality of first electrodes formed on the first substrate; a partition having a plurality of switch holes and formed on the first electrode; and a plurality of driving bodies disposed one by one in each of the switch holes, wherein the electric field driving display device is divided into gray regions including at least one of the switch holes and pixel regions including a plurality of gray regions, and drives the driving body as a unit of the gray region, thereby displaying a gray.

[Claim 2] The electric field driving display device of claim 1, further comprising: a second substrate disposed on the partition; and a second electrode formed on the second substrate.

[Claim 3] The electric field driving display device of claim 2, further comprising color filters of red, green, and blue formed on the second substrate, wherein the color filters have different colors per pixel region.

[Claim 4] The electric field driving display device of claim 3, wherein the gray region has a first region, a second region, and a third region.

[Claim 5]

The electric field driving display device of claim 4, wherein there are 48 switch holes for each pixel region.

[Claim 6]

The electric field driving display device of claim 5, wherein each switch hole includes a fixing groove and a driving groove, the first electrode is exposed through the fixing groove, and the second electrode is exposed through the driving groove.

[Claim 7]

The electric field driving display device of claim 6, wherein the area of the cross-section of the driving groove is increased moving away from the first substrate.

[Claim 8]

The electric field driving display device of claim 7, wherein the second electrode is disposed on the edge of the cross-section of the driving groove.

[Claim 9]

The electric field driving display device of claim 5, wherein the driving body has a spherical shape.

[Claim 10]

The electric field driving display device of claim 9, wherein the driving body diameter is equal to or more than the width of the fixing groove.

[Claim 11]

The electric field driving display device of claim 10, wherein the position of the driving body is determined by the voltage applied to the first electrode and the second electrode. [Claim 12]

The electric field driving display device of claim 1, further comprising a backlight unit supplying light toward the first substrate for a display, wherein the backlight unit has a condenser lens condensing the light toward the driving groove.