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Publication numberUS3924228 A
Publication typeGrant
Publication dateDec 2, 1975
Filing dateJan 6, 1975
Priority dateJan 6, 1975
Also published asCA1039838A1, DE2556946A1, DE2556946B2, DE2556946C3
Publication numberUS 3924228 A, US 3924228A, US-A-3924228, US3924228 A, US3924228A
InventorsGoodrich George W
Original AssigneeBendix Corp
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electrostatically actuated display panel
US 3924228 A
Abstract
An electrostatically actuated character generating display panel is disclosed. The display panel embodies one or more flexible membrane sections disposed in a predetermined pattern in an electric field generated between a transparent window and a closely spaced parallel support substrate. By electrically charging the individual membrane sections, electrostatic forces are generated which displace the charged sections either to or away from the window. The space between the window and the substrate is filled with a contrasting colored, high dielectric opaque fluid which normally occludes the membrane sections when they are displaced towards the substrate. When the electrostatic forces displace the membrane sections against the window, the membrane displaces the opaque fluid and the contacting portion of the membrane section becomes visible through the window. Selectively charging individual membrane sections in the pattern, indicative of the character to be formed, selectively displaces the charged membrane sections against the window and the desired character is visually formed. Alternatively, a message imprinted upon a single segment can similarly be made to appear or disappear.
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j United States 11 3,924,228

Goodrich 51 Dec. 2. 1975 [541 ELECTROSTATICALLY ACTUATED [57] ABSTRACT DISPLAY PANEL UNITED STATES PATENTS 11/1956 Marcy 340/378 R 12/1964 Cunnien... 340/366 R 10/1965 Jacob... 340/366 R 4/1968 Kushner eta. 340/324 R 1/1971 Banks et a1. 350/161 5/1974 Goodrich 340/324 R 7/1974 Passien 340/378 R Primary ExaminerDavid L. Trafton Attorney. Agent. or FirmJames R. lgnatowski CONT/Q04 LOG/C An clectrostatically actuated character generating display panel is disclosed. The display panel embodies one or more flexible membrane sections disposed in a predetermined pattern in an electric field generated between a transparent window and a closely spaced parallel support substrate. By electrically charging the individual membrane sections. electrostatic forces are generated which displace the charged sections either to or away from the window. The space between the window and the substrate is filled with a contrasting colored. high dielectric opaque fluid which normally occludes the membrane sections when they are displaced towards the substrate. When the electrostatic t'orces displace the membrane sections against the window. the membrane displaces the opaque fluid and the contacting portion of the membrane section becomes visible through the window. Selectively charging individual membrane sections in the pattern. indicative of the character to be formed. selectively displaces the charged membrane sections against the window and the desired character is visually formed. Alternatively. a message imprinted upon a single segment can similarly be made to appear or disappear.

38 Claims. 9 Drawing Figures CHARACTER m/puT US. Patent Dec. 2, 1975 Sheet 1 01 4 3,924,228

(O/VTROL 406/6 CHAR/1675f? P 7' FIGI onvu

FIG-2 US. Patant Dec. 2, 1975 Sheet 2 014 3,924,228

US. atent Dec. 2, 1975 Sheet 3 of4 3,924,228

FIG.6 l

LOG/C CONTROL 106/6 CONTROL US. Patent Dec. 2, 1975 Sheet 4 of4 3,924,228

FIG. 8

5 1 W BRAKE/FLU/D LOW T ELECTROSTATICALLY ACTUATED DISPLAY PANEL BACKGROUND OF THE INVENTION 1. Field of the Invention The invention is related to the field of visual communications and, in particular, to passive display panel producing alpha numerical characters by electrostatically moving selected flexible membrane sections against the surface of a transparent window displacing an opaque fluid disposed therebetween and forming visible characters.

2. Prior Art Display panels may be roughly categorized as luminous or passive dependent upon whether they are self luminous or require ambient light to relay the information to the recipient. Luminous display panels, such as cathode ray tubes, arrays of light emitting diodes, and plasma panels have found wide acceptance in both industry and general public use. The deficiency of luminous display panels is the tendency of the information displayed to be washed out, and even lost under intense ambient illumination. In contrast, passive display panels transmit the information to the recipient by means of reflected ambient light and visibility increases with increased ambient illumination. Passive display panels have practical application where the ambient illumination may vary from intense daylight to subdued conditions.

Passive display panels range in form from the time honored score boards found in baseball parks to the more recent electronically activated liquid crystal displays and includes various types of panels in which the information is made visible by displacing an opaque fluid filling the space between a transparent window and the desired information. The displacement of the opaque fluid is generally accomplished by moving the information bearing member into physical contact with the window. The physical contact displaces the fluid from between the window and member and the information, otherwise occluded by the opaque fluid, becomes visible. The prior art teaches the displacement of information or character bearing members by mechanical, pneumatic, fluidic and electromagnetic forces. G. A. Wearham, in U.S. Pat. Nos. 1,780,733 and 1,782,328 teaches the displacement of the member by both mechanical and fluidic means. J. M. Cunnien, in U.S. Pat. No. 3,162,849 introduces the concept of using electromagnetic means for moving the character bearing member. These early displays are confined to simple on/off devices and were incapable of generating individual characters of various forms in any one given location on the face of the panel.

Many of the present applications for display panels require high character densities which may be changed upon command and the simple on/off configurations of the prior art are incapable of meeting this requirement.

An initial attempt to overcome this problem is disclosed in my earlier U.S. Pat. No. 3,812,490, Flexible Membrane Display Panel for Generating Characters Visible in Ambient Light. This device uses a magnetized flexible membrane disposed in an opaque fluid a short distance from a window. The membrane is selectively deflected to form the desired characters by a matrix of small electromagnets formed on a magnetically susceptible substrate disposed behind the magnetized membrane on the side opposite the window. This electromagnetically activated display panel represents one solution to the problem.

The prior art further reveals that others have attempted to use electrostatic forces to activate passive display panels. W. R. Aiken in U.S. Pat. No. 3,304,549 discloses a Composite Signaling Device" in which a matrix of hinged vanes representing various segments of a character are displaced by electrostatic forces from a horizontal to vertical position making them visible through a transparent window. In an alternate configuration, as disclosed by Dahms et a1, a hinged vane or flag is systematically deflected to one or the other side of V-shaped grooves to form the desired character. The opposite sides of the vanes and opposite sides of the V-shaped grooves have the same contrasting colors. The vanes are arranged so that each face of vane has the same color as the adjacent face of the groove, so that when the vane is deflected to one side, the exposed face of the vane and the exposed surface of the V groove have the same color, and when the vane is deflected to the other side, the opposite side of the vane and the other face of the groove are exposed, displaying the contrasting color. In both of these types of displays, the vane is required to move through a considerable distance and relatively high electrostatic voltages are required. Electrostatic deflection of a reflective membrane for light modulators has also been used with large screen television displays. Typical examples of such devices are disclosed by P. Kendall, Jr. et a1, U.S. Pat. No. 3,796,480, as well as my own U.S. Pat. No. 3,746,785.

SUMMARY OF THE INVENTION The invention is an electrostatically actuated passive display panel. The panel comprises a plurality of electrically isolated conductive membrane sections systematically disposed along the surface of a support structure in a predetermined pattern. A transparent window having an electrically conductive internal surface is disposed parallel to the support structure and proximate the conductive membrane sections so that a distance of approximately 0.01 centimeter separates the window from the adjacent surfaces of the membrane section. The space between the window and the membrane sections is filled with a low conductivity, high dielectric constant, colored fluid having sufficient opacity to occlude the membrane section when viewed through the window. One end of each membrane section is fixedly attached to the support structure and the opposite end is free to move under the influence of internally generated electrostatic forces. Under the influence of electrostatic forces, the free ends of the membrane sections contact the inner surface of the transparent window. The free end of each membrane section has a region imprinted with a color contrasting to the color of the fluid so that when the free end is in contact with the window, the contrasting color of the imprinted region is visible therethrough. Means are further provided for generating an electric field between the conductive surface disposed along the inner surface of the window and the support structure and for individually conducting an electrical charge to each electrically isolated membrane section. Selectively charging individual membrane sections with electrical signals, having a polarity the same as that applied to the support structure, will generate an electrostatic field and therefor an electrostatic force between the window and the charged membrane sections. The attractive electrostatic force urges the free ends of the charged membrane sections away from the support structure and into contact with the window, displacing the opaque fluid and rendering the region imprinted with the contrasting color to be visible. Reversing the polarity of the charge on the individual membrane sections so that it will have the same charge as on the window will return their free ends to their original position along the support substrate.

In a preferred embodiment, the membrane sections are arranged in the familiar seven bar alpha numerical pattern, including an eighth membrane section for generating a period or decimal point. The invention may be embodied in an elementary form containing only a single membrane section with an imprinted message or a single alpha numerical pattern. The display may also take more complex forms having a plurality of patterns arranged in linear or in two dimensional matrices. The electrical power and potentials required for activation of the electrostatically activated display panel are well within the state of the art of solid state logic and switch ing devices, and may be either AC or DC.

The object of the invention is a passive electrostatically activated display panel compatible with state of the art logic circuitry and components having a high character density. A further object of the invention is a multiple character passive display panel relatively simple and inexpensive to make. Still another objective of the invention is a multiple character passive display panel using no exotic or expensive components or manufacturing techniques. Another object is a display panel which may be matrix addressed or multiplexed. These and other objectives will become evident from a reading of the following detailed description of the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exaggerated cross section view of a preferred embodiment of the electrostatically activated display panel to show the individual elements and con struction details.

FIG. 2 is a plan view of the membrane sections arranged in the familar seven bar alpha numerical pattern.

FIG. 3 is a plan view of an alternate embodiment of the composite base having the leads to the individual membrane sections along a common edge.

FIG. 4 is a cross section of the alternate embodiment shown in FIG. 3.

FIG. 5 is a cut away perspective illustrating a multi character embodiment of the display panel.

FIG. 6 is a plan view of an alternate embodiment of a composite substrate for a display panel capable of being multiplexed.

FIG. 7 is a plan view of an alternate embodiment of a composite substrate for a panel capable of being matrix addressed.

FIG. 8 is a plan view of a composite base having a single membrane section with a printed message.

FIG. 9 is a plan view of a composite base having an alternate configuration for the membrane sections.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The details of the preferred embodiment of the electrostatically activated membrane panel is discussed with reference to the exaggerated cross sectional view of FIG. 1. This cross sectional view shows the basic elements and these physical relationships to each other.

a: Referring to FIG. 1, the body of the display panel comprises a composite transparent window 10, a composite membrane support base 12 and a spacer body 14. The composite window 10. composite base 12 and spacer body 14 form a structure having an internal cavity completely filled with a low conductivity opaque fluid 16. The composite window comprises a window 18, such as glass or any other suitable transparent material and has a transparent conductive coating of any type known in the art which is applied along the inner surface of the window 18. The transparent conductive coating 20, for example, may be a tin oxide coating, such as the commercially available NESA coating or a transparent vapor-deposited metalic film. The conductive coating 18 is further overlaid with an insulation material 22. When the conductivity of the insulating material 22 is approximately equal to the conductivity of the opaque fluid 16, the insulating material may be in the form of a continuous layer disposed over the conductive coating 20. However, when the conductivity of the insulating material is substantially less than that of the opaque fluid, the insulating material may be disposed over the conductive coating 20 in the form of a plurality of isolated islands such as would be obtained by evaporating silicon monoxide or other insulating material through a fine mesh screen. The spacing between the isolated islands being sufficiently small to prevent the conductive deflectable membrane sections 28 from contacting the conductive coating 20 between the islands.

The composite membrane support base 12 in the illustrated embodiment of FIG. 1 comprises a metal plate 24 overlaid with an insulating material 26. Like the composite window, when the conductivity of the insulating material 26 is approximately equal to the conductivity of the opaque fluid 16, the insulating material may be in the form of a thin continuous layer disposed over the internal surface of the metal plate 24. However, when the conductivity of the insulating material is substantially less than the conductivity of the opaque fluid, the insulating material may be disposed along the surface of the metal plate in the form of a plu rality of isolated islands. The island configuration of the insulating material on the composite window and composite base permits the opaque fluid, having the higher conductivity, to be in electrical contact with conductive surfaces of the window and the base and enhances the establishment of a more uniform electrical field therebetween. In alternate embodiments, to be discussed hereinafter, the composite base 12 may be made from an insulating material with a conductive coating disposed along the surface thereof. Attached to the insulating material 26 are a plurality of electrically isolated deflectable membrane sections 28 which will be discussed in detail with reference to FIG. 2. Electrical contact to each individual membrane section 28 is made by a like plurality of conductor elements, illustrated as pins 30 making electrical contact with each membrane section and passing through the metal plate 24- and insulating material 26 to the external surface of the display panel. By this means each membrane section 28 may be individually charged by an electrical potential applied to the associated pin 30. Insulator grommets 32 are provided for electrical isolation between each pin 30 and the metal plate 24.

The spacer body 14 is made from an insulating material and provides a circumferential fluid seal between the composite window 10 and the composite support plate 12. The thickness of the spacer body 14 is selected so that the separation between the inner surface 34 of insulation layer 22 and the upper surface 36 of the membrane sections 28, indicated as dimension is approximately 0.01 centimeter.

The opaque fluid 16 is a high dielectric constant, low conductivity, colored fluid such as ethyl acetate, colored with a commercial oil soluble dye.

Electrical power is applied to the transparent conductive layer 20 and the metal plate from a source of electrical power illustrated as battery 38. Electrical power is also applied to each of the membrane sections 28 via pins 30 and connecting leads from a control logic circuit 40. The control logic circuit 40 has an input indicative of the character to be formed. This input may be a manual input from a keyboard, or an electrical signal from an external source (not shown). The various types of inputs and the manner in which they are generated are well known in the art and need not be discussed for an understanding of the invention. The control logic circuit may be powered from the same source as the display panel, as shown, or may be powered by an independent electrical source. The control logic circuit is of conventional form and in response to an input indicative of a specific character outputs electrical signals on the leads connected to the pins 30. In the preferred embodiment, the output sig nals from the control logic are bipolar electrical signals having either a magnitude and polarity the same as that applied to the transparent conductive layer 20 or the magnitude and polarity the same as that applied to the metal plate 24 from the electrical power source.

The details of the membane sections 28 are discussed with reference to FIG. 2. This illustrated embodiment comprises eight electrically isolated membrane sections 28. Seven of the sections are arranged to define the elements of a typical seven bar alpha numerical character and the eighth section is a period or decimal point. The use of this pattern to generate both letters and numerals is well known and need not be further discussed. The membrane sections 28 may be a thin metal foil such as 2 um thick aluminum foil or made from a thin sheet or film of a suitable plastic material, as polyester or polyvinyl chloride, heavily loaded with conducting particles, such as carbon black, so that each section is electrically conductive and assumes a common electrical potential when charged. Alternatively, the plastic film may be metalized, using conventional metal deposition methods, such as vapor deposition to provide the desired electrical conductivity. In cases where the electrical charge leaking from the individual sections may otherwise cause life limiting electrolysis of the opaque fluid 16, a thin insulating layer may be deposited over the conductive surfaces of the individ ual membrane sections as a barrier to electronic exchange to ions in the fluid.

Each membrane section 28, forming the alpha numerical character, is comprised of three regions, as il lustrated. The first region, arbitrarily defined by the crosshatched area, is electrical contact region 42, which is fixedly attached to the insulating material 26 and in electrical contact with the associated pin 30. This may be accomplished using a conductive epoxy or by depositing a thin layer of indium or an indium alloy in the contact region of each membrane section 28 and affecting a cold indium weld between the layer of insulating material 26 and the contact region 42 of the membrane section. The second region, defined by the diagonal bar pattern, is the hinge region 44 and is that segment of the membrane which flexs when the section is subjected to electrostatic forces. The third region is the imprinted region 46 which is imprinted with a color contrasting to the color of the opaque fluid 16. For example, if the opaque fluid is white, the imprinted region would be black and vice versa. Obviously, other contrasting color combinations including the use of fluorescent colors on the imprinted regions could also be used if so desired. To improve the sharpness of the generated character, the hinge region 44 and contact region 42 may be colored to blend in with the color of the opaque fluid. Alternatively, an opaque mask deposited on the inside surface of the window could be used to occlude the hinge and contact regions of the sections. The surface of the membrane sections 28 may be con tinuous or porous. A porous membrane would permit fluid to flow through the membrane reducing its resistance to movement thereby increasing the response time of display panel.

The operation of the display panel is as follows:

An electrostatic potential difference is established between the transparent conductive coating 20 disposed over the inner surface of the composite window It) and the metal plate 24 by means of the source of electrical power supply, such as battery 38. Information indicative of the character to be displayed is input into the control logic 40 which generates electrical signals communicated to the respective pins 30 on the display panel. The pins in electrical contact with the membrane sections 28, which form the input character, receive electrical signal having approximately the same magnitude and polarity as the potential the metal plate 24. The membrane sections forming the input character assume the potential communicated to their respective pins and are subjected to an electrostatic force urging the free imprinted region 46 of the membrane sections towards the composite window 10. Under the influence of these electrostatic forces, the imprinted region of the membrane sections contact the transparent insulation material 22 overlaying the conductive layer 20 and displaces the opaque fluid 16 from therebetween. With the opaque fluid 16 so displaced, the im printed region 46 of each membrane section in contact with the transparent insulation material 22 becomes visible through the composite window It) and the input character is formed.

The remaining membrane sections receive signals from the control logic which have approximately the same magnitude and polarity as potential on the conductive coating 20 and are held against the insulation material 26 overlaying the metal plate 24 by electrostatic forces generated between the membrane sections and the support substrate.

The electrical potentials required to displace the membrane sections against the window appear to be well within the output capabilities of state of the art solid state logic circuitry. Buffer or interface amplifiers to increase voltage or current levels are not required. The force of attraction per unit area between two parallel conductors can be derived from the energy stored in a capacitor. The electrostatic force P is defined by the equation:

7 Where F,, the force per unit area between two parallel conductors (dynes/cm V the potential difference between the two parallel conductors (volts) .\"=the distance between the conductors (cm) and k the dielectric constant of the medium between the conductors (opaque fluid).

The dielectric constant of distilled water is 80, for glycol (C H O 38 and furfural (C H O is 42. If we assume a dielectric constant lc=50, V=l0 volts x=x 0.()l cm, then the electrostatic force F dynes/cm which is higher than a force experimentally known to be adequate to displace the membrane section against the window. Therefore, a display panel built in accordance with the disclosed principles will work.

While the electrical power supply has been illustrated as a DC source of electrical power and the operation of the panel discussed in terms of DC operation, the display panel is also operable with alternating (AC) potentials. The requirement for AC operation is that all applied potentials including the signals to the membrane sections be changed in a synchronous manner so that the directions of the electrostatic forces are unchanged. AC operation of the panel is desirable because it significantly reduces the electrolysis of the opaque fluid and increases the life of the panel.

An alternate embodiment of the composite base eliminating the pins protruding therethrough for electrical contact to the membrane sections is shown in FIGS. 3 and 4. In this embodiment, electrical conduc tors 48 are deposited on an insulator substrate 50 made from glass or one of the commercially available plastics. The conductors originate from a common edge of the substrate, indicated as edge 52, and individually terminate at a location under one of the contact regions 42 of the associated membrane sections 28 (shown in phantom). The conductors 48 may be formed on the insulator substrate 50 using any of the methods well known in the art, such as vapor deposition, silk screening, etc. The conductors 48 are overlaid with a thin film of insulating material 54 such as silicon monoxide, except for the contact area 56 under the contact regions 42 of the membrane sections. The entire surface area of the support substrate 50, again, with the exception of contact areas 56, is overlaid with a conductive film 58 which in turn is covered with insulator material 60. The membrane sections 28 are attached to the composite substrate 12 in the desired positions and in electrical contact with the individual conductors 48 using any of the methods well known in the art. The membrane sections may be attached to the composite substrate using a conductive epoxy or a thin layer of indium 62 over the area on the composite substrate 12, defined by the contact region 42 of each membrane section 28.

FIG. 9 illustrates an alternate configuration of the deflectable membrane sections 28 forming the alpha numerical character. In this configuration, the hinge region 72 is connected to the narrow ends of the imprinted region 74 and are substantially longer than they are wide to provide increased flexibility of the hinge. The hinge region may be colored to blend in with the color of the opaque fluid, as discussed with reference to FIG. 2, or a mask having the same color as the opaque fluid may be imprinted on composite window 10 to occlude the hinge region of the individual sections 28. The dashed lines 76 outline the areas on the composite window to be masked when this latter concept is employed. The areas 78 (diagonal lines) indicate the areas to which a conductive epoxy or other bonding agent is applied to attach the membrane sections to the composite substrate 12. The operation of the display panel is the same as discussed with reference to FIG. 1.

Although the display panel has been illustrated and described in FIGS. 1 through 4 as having only a single alpha numerical character, it is obvious that the con cept can be extended to a multiple character panel, as shown in FIG. 5. The numbers used to identify the elements illustrated in FIG. 5 are the same as used in FIGS. 1 through 4.

The multi character panel may be activated using any of the methods presently available in the art including multiplex or matrix address techniques which require fewer leads between the display panel and the control logic.

To multiplex a multi character panel, such as illustrated in FIG. 5, the structure of the composite base may be made as shown on FIG. 6. In this illustration the insulator substrate 50 and electrical conductors 48 depicted in FIG. 3 are understood but not shown to simplify the drawing. The continuous conductive film 58 is segmented into a plurality of electrically isolated conductive islands 64 which may be individually charged by means of the logic control 66. The corresponding sections 28 of each character on the multi character display are electrically connected in parallel to the logic control 66. The parallel electrical connections of the corresponding sections may be made during the fabrication of the composite base 12 or be made externally, as shown. The operation of the multiplexed panel is as follows:

All of the islands 64 are initially electrically biased to the same potential as the window, with the exception of the addressed island associated with the character, the position of whose membrane sections are to be set. The potential of the island being addressed is different from that of the window to generate an electric field, as discussed relative to FIG. 1. All the sections are then charged for a short fraction of one clock cycle with a polarity opposite that of the window, i.e., the nominal potential applied to the conductive film on the composite base. Because the window and the nonaddressed islands have the same electrical potential, the sections associated with the nonaddressed islands are attracted to the closest electrode, be it the window or the composite base. For the remainder of the clock cycle, the sections to be displaced towards the window remain at the potential of the addressed island and the sections to be displaced against the composite base are biased to the potential of the window. The sections at the window potential and associated with the nonaddressed islands will not move since there is no field gradient between the window and the islands and the sections will float electrically. Only the sections associated with the addressed island will be attracted to the composite substrate. The sections to be displaced against the window are charged to the potential of the addressed island. The sections associated with the nonaddressed islands, as discussed above, are attracted to the nearest electrodes and, therefore, will retain their initial position,

either against the window or against the composite base. The sections associated with the addressed island will be displaced against the window by electrostatic forces. By serially addressing the islands associated with each character on the panel, multiplexed operation may be achieved. Logic controls for performing the required function and generating the required potentials are well within the state of the art. The location of the island being addressed can be determined from a pair of shift registers and the sections being driven in parallel from a third shift register device. The information indicative of the characters to be displayed is serially generated and loaded into the section shift register device. When the section shift register is loaded, the island location shift registers are indexed to the next sequential island location and both signals are simultaneously applied to the panel.

For matrix operation, the structure of the composite substrate 12 may be made as shown on FIG. 7. Again, the substrate 50 and conductors 48 are not shown to simplify the drawing. The continuous conductive film 53 is segmented into a plurality of electrically isolated conductive stripes 68 disposed in a plurality of rows which may be individually charged by a logic control 70. Each conductive stripe 68 being associated with one row of characters on the multi character display panel. The characters are divided according to columns and corresponding sections 28 in each character in each column are electrically connected in parallel. The parallel electrical connection between corresponding sections in each column can be made during the fabrication of the composite substrate or made externally as shown. Although only four characters are illustrated, two in each row, and two in each column, the concept is readily extended to many rows and columns having many characters each.

The matrix operation of the display panel is similar to the multiplex operation. Initially, all the rows 68 are charged to the potential of the window except the row containing the character whose sections are to be charged. The information indicative of the sections to be displaced either towards or away from the window is applied to the respective leads on the column containing character. Obviously, the characters in the unaddressed columns will not change, and for the reasons discussed with reference to multiplex configurations, only the sections in the addressed column which are in the character in the activated row will change. All other characters will remain unchanged. By sequentially switching the activation of the individual rows and columns in a predeterminable order, each charac ter can be changed in accordance with the signals generated by the logic control. It would be obvious to one skilled in the art that the conductive stripes 68 could be disposed along the columns and that the parallel connection of the like character sections could be made along the rows without departing from the intent of the invention.

Having described the invention in terms of a panel having alpha numerical characters, it is recognized that other types of character patterns may be equally employed within the spirit of the invention.

One such character pattern is the conventional by 7 dot matrix in which the characters are formed by activating predetermined dots within the matrix. In this embodiment, the conductive film on the composite substrate is segmented into a plurality of electrically isolated conductive stripes, one stripe for each row of dots in the pattern. The membrane sections take the form of a plurality of parallel stripes angularly disposed to the conductive stripes; one parallel membrane section for each column in the dot pattern. The intersections between the conductive stripes and the parallel membrane sections represent dots in the pattern. From the prior discussion with reference to FIG. 6 and 7, it is readily seen that by matrix addressing each row of conductive stripes and each column of membrane section in a predeterminable sequence the membrane sections at selected intersections can be deflected into contact with the window to form the desired character.

In contrast to the multi character panels of FIGS. 5, 6 and 7, the principles of the electrostatic display panel may be embodied in a simple on/off type display having a predetermined message imprinted on a single moveable membrane, such as shown in FIG. 8. It is understood that this type of display may have more than one moveable membrane and more than one printed message. The operation of the display panel illustrated in FIG. 8 is the same as the character forming configuration discussed with reference to FIGS. 1 and 2 and need not be repeated here. One skilled in the art will immediately conceive other embodiments based on the disclosed principles of operation. The embodiments illustrated and discussed are merely to present the invention in several of its many forms and are not intended to limit the scope of the invention.

What is claimed is:

1. An electrostatically actuated display panel comprising:

a composite base having at least one electrically conductive planar surface and a thin surface layer of insulating material disposed over said conductive surface,

at least one electrically isolated, electrically conductive, flexible membrane section having a predetermined color, said membrane section having at one end a predetermined contact region fixedly attached to said composite base on the side having said layer of insulating material and electrically isolated from said conductive surface, the opposite end of said at least one membrane section being free to move under the influence of electrostatic forces;

means for conducting an electrical charge to said at least one membrane section;

a composite planar window disposed parallel to said composite base and separated therefrom by a predetermined distance slightly greater than the thickness of said membrane section, said composite window having a thin layer of transparent electrically conductive material disposed along the surface of I said window adjacent to said composite base;

means rigidly supporting said composite window from said composite base and forming a peripherial fluid seal between said composite base and said composite window; and

a low conductivity high dielectric constant fluid, having a color contrasting to the color of said at least one membrane section, filling in the space between said composite window, and said composite base, said fluidhaving an opacity sufficient to occlude viewing of said at least one membrane section when said membrane section is disposed against the surface of said composite base.

2. The display panel of claim 1 wherein said at least one electrically conductive flexible membrane section 1 1 comprises a thin sheet of flexible material having a length substantially longer than its width, said sheet of flexible material having said predetermined contact region at one end, an imprinted region at the end opposite to said one end, and a hinge region disposed between said electrical contact region and said imprinted region.

3. The display panel of claim 2 wherein only said imprinted region has said predetermined color, said contact region and said hinge region having a color blending with the color of said opaque fluid.

4. The display panel of claim 2 wherein said thin sheet of flexible material is porous to said opaque fluid.

5. The display panel of claim 4 wherein said thin sheet of flexible material is nonconductive, said membrane section further includes conductive material embedded in said thin sheet of material to render said material conductive.

6. The display panel of claim 4 wherein said thin sheet of flexible material is nonconductive, said membrane sections further include a thin layer of conductive material disposed over at least one surface of said thin sheet.

7. The display panel of claim 4 wherein said thin sheet further includes a thin layer of insulator material disposed over surface of said membrane sections.

8. The display panel of claim 4 wherein said at least one membrane section is only one membrane section and said imprinted region has a predetermined message printed thereon.

9. The display panel of claim 4 wherein said at least one membrane section is a plurality of membrane sections electrically isolated from each other, each of said membrane sections having a message printed on said imprinted regions and wherein said means for conducting independently conducts an electrical charge to each of said plurality of membrane sections.

10. The display panel of claim 2 wherein said at least one membrane section comprises a plurality of electrically isolated, electrically conductive, flexible membrane sections disposed along the surface of said composite base in at least one predetermined character forming pattern, and said means for conducting independently conducts an electrical charge to each of said membrane sections.

11. The display panel of claim wherein said at least one predetermined character forming pattern comprises at least seven of said electrically conductive flexible membrane sections arranged to form a block numeral eight.

12. The display panel of claim 11 wherein said character forming pattern further includes an eighth electrically conductive flexible membrane section within the block numeral eight to form a period.

13. The display panel of claim 10 wherein said at least one character forming pattern comprises a plurality of character forming patterns linearly disposed along a straight line.

14. The display panel of claim 10 wherein said at least one character forming pattern comprises a plurality of character forming patterns disposed in a multi line matrix.

15. The display panel of claim 1 wherein said composite window further includes a thin. transparent layer of insulating material disposed over the transparent conductive material.

16. The display panel of claim 15 wherein said layer of insulating material disposed along the surface of said composite window comprises a plurality of small isolated islands of insulating material systematically disposed over the transparent conductive material, and said layer of insulating material disposed along the surface of said composite base also comprises a plurality of small isolated islands of insulating material systematically disposed along said conductive surface, further wherein each island of insulating material disposed along said composite window and said composite base are separated from all adjacent islands by a distance sufficiently small to support said flexible membrane sections in electrical isolation from said conductive material and said conductive surface respectively.

17. The display panel of claim 1 wherein said composite base includes a rigid metal plate wherein said conductive surface is one surface of said metal plate.

18. The display panel of claim 17 wherein said metal plate further includes a plurality of holes therethrough, one hole being disposed in the contact region of each membrane section, said means for conducting an electrical charge to each membrane section is a plurality metal conductor wire having a diameter smaller than the diameter of said holes and a length substantially longer than the thickness of said metal plate, one of said metallic conductor wires concentrically disposed in each of said holes with one end of said conductor wires flush with the surface of said insulating material and in electrical contact with said contact regions and insulating material disposed between said metal plate and said conductor wires, electrically insulating said wires from said metal plate.

19. The display panel of claim 1 wherein said composite base includes a rigid plate of insulator material and said conductive surface is a thin layer of conductive material disposed over the surface of said rigid plate of insulator material on the side adjacent to said composite window.

20. The display panel of claim 13 wherein said composite base includes a base substrate of insulator material and said conductive surface comprises a plurality of conductive islands disposed over the surface of said base substrate, each of said conductive islands being associated with at least one of said character forming patterns.

21. The display panel of claim 14 wherein said composite base includes a base substrate of insulator material and said conductive surface comprises a plurality of conductive islands disposed over the surface of said base substrate, each of said conductive islands being associated with at least one of said character forming patterns.

22. The display panel of claim 10 wherein:

said character forrnin g pattern is a multi element dot type matrix having a predetermined number of elements systematically arranged along two axes angularly disposed to each other,

said composite base includes a base substrate of insulator material and said conductive surface comprises a plurality of electrically isolated conductive stripes disposed parallel to one of said two axes, said plurality of conductive stripes equal to the number of elements in said multi element matrix along the other of said two axes,

said membrane sections comprise a plurality of narrow membrane sections disposed parallel to said other axis, said plurality of membrane sections equal in number of elements in said multi element matrix along said one axis.

23. The display panel of claim 1 wherein said predetermined distance is of the order of 0.01 centimeter.

24. The display panel of claim 1 wherein said opaque fluid comprises a mixture of ethyl acetate and oil soluble dye.

25. An electrostatically actuated display panel system comprising:

a composite base having an electrically conductive planar surface and a thin surface layer of insulating material disposed over said conductive surface;

a plurality of thin electrically isolated electrically conductive flexible membrane sections disposed along the surface of said composite base having said insulating material in at least one predetermined character forming pattern, each of said membrane sections having along one edge a predetermined contact region fixedly attached to said composite base and an imprinted region at the opposite end having a predetermined color, each of said membrane electrically isolated from said conductive surface;

means for independently conducting an electrical charge to each of said membrane sections;

a composite window disposed parallel to said composite substrate and separated therefrom by a predetermined distance slightly greater than the thickness of said membrane sections, said composite window having a thin layer of transparent electrically conductive material disposed along the sur face of the composite adjacent to said composite substrate;

a peripheral support means rigidly positioning said composite window with respect to said composite substrate and providing a peripheral fluid seal therebetween;

a low conductivity, high dielectric constant fluid having a color contrasting to the color of said imprinted region, filling in the space between said composite window and said composite substrate, said fluid having an opacity sufficient to occlude the' viewing of said imprinted region when said membrane sections are disposed against the surface of said composite substrate;

a source of electrical power having at least two outputs of different electrical potentials, one of said outputs providing electrical power to the conductive surface of said composite base substrate, the other output providing electrical power to the conductive material disposed along the surface of said transparent window; and

control logic means electrically connected to the means for conducting an electrical charge to each of said membrane sections for generating electrical signals charging predetermined membrane sections in response to input signals indicative of character to be generated.

26. The display panel system of claim wherein:

said source of electrical power is an AC source of electrical power wherein the potential of said two outputs alternate at a predetermined frequency, and wherein the potential of the signals generated by said control logic means synchronously alternate with two outputs of the AC power source to maintain the relationship between the potentials applied to the conductive surface of said composite base and the conductive material disposed along the surface of said transparent window, and signals applied to the membrane sections.

27. The display panel system of claim 28 wherein said membrane sections are porous to said opaque fluid.

28. The display panel system of claim 25 wherein said composite window further includes a thin transparent layer of insulating material deposited over the transparent conductive material.

29. The display panel system of claim 28 wherein said layer of insulating material deposited along the surface of said composite window comprises a plurality of small isolated islands of insulating material systematically disposed over the transparent conductive material, and said layer of insulating material disposed along the surface of said composite base also comprises a plurality of small isolated islands of insulating material systematically disposed along said conductive surface, further, wherein each island of insulating material disposed along said composite window and said composite base are separated from all adjacent islands by a distance sufficiently small to support said membrane sections in electrical isolation from said conductive material and said conductive surface respectively.

30. The display panel system of claim 25 wherein said at least one predetermined character forming pattern comprises at least seven linear electrically conductive flexible membrane sections arranged to form a block numeral eight, and further includes an eighth electrically conductive flexible membrane section within the block numeral eight to form a period.

31. The display panel of claim 25 wherein said at least one character forming pattern comprises a plurality of character forming patterns disposed along a straight line.

32. The display panel of claim 31 wherein the conductive planar surface of said composite base comprises a plurality of electrically isolated conductive islands disposed along said straight line of character forming patterns with at least one of said islands being disposed under each of said patterns;

further, wherein corresponding membrane section in each of said character forming patterns are electrically connected in parallel to said control logic means; and

wherein said logic control means includes:

means for generating electrical signals indicative of the character to be generated for each of said character forming patterns in a predetermined sequence; and

means for applying to each of said islands, one at a time, in said same predetermined sequence and in synchronization said electrical signals, said one output from the source of electrical power while simultaneously applying to all other islands, said other output from the source of electrical power.

33. The display panel system of claim 25 wherein said at least one character forming pattern comprises a plurality of character forming patterns systematically disposed along the surface of said composite base in a multi line matrix of character forming patterns.

34. The display panel of claim 33 wherein the conductive planar surface of said compositevbase comprises a plurality of electrically isolated conductive planar islands in a multi line matrix corresponding to the multi line matrix of character forming patterns, each of said islands being associated with a corresponding character forming pattern;

further, wherein corresponding membrane sections in each of said character forming patterns are electrically connected in parallel to said control logic means; and

wherein said logic control means further includes:

means for generating electrical signals indicative of the character to be generated for each of said character forming patterns in a predetermined sequence; and

means for applying to each of said islands, one at a time, in said same predetermined sequence and in synchronization with said electrical signals, said one output from the source of electrical power while simultaneously applying to all other islands said other output from the source of electrical power,

35. The display panel system of claim 33 wherein said multi line matrix has the character forming patterns disposed at the intersections of two interlaced sets of parallel lines angularly disposed to each other;

said conductive planar surface of said composite base comprises a plurality of electrically isolated conductive stripes disposed parallel to one of said two sets of lines, one of said parallel stripes corresponding with the patterns lying along each line in said one set of lines;

further, wherein corresponding sections of each character forming pattern lying along each line of the other set of parallel lines are electrically connected in parallel; and wherein said logic control means further includes; means for generating electrical signals indicative of the characters to be generated for each character forming pattern in a first predetermined sequence;

means for applying said electrical signals to the parallel connected membrane sections of the patterns lying along said other set of parallel lines in a second predetermined sequence, said second predetermined sequence applying said signals to the line of patterns containing the pattern in which the character is to be generated; and

means for applying to the conductive stripes, said one output from the source of electrical power in a third predetermined sequence while simultaneously applying to all other stripes said other output from source of electrical power, said third predetermined sequence applying said one output to the conductive stripe associated with the line of l6 patterns having the pattern in which the character is to be generated.

36. The display panel of claim 35 wherein said two interlaced sets of parallel lines are angularly disposed at right angles to each other.

37. The display panel system of claim 25 wherein:

said character forming pattern is a multi element dot type matrix having a predetermined number of elements systematically arranged at the intersections of two sets of parallel lines angularly disposed to each other;

said conductive planar surface of said composite base comprises a plurality of electrically isolated conductive stripes, each of said plurality of conductive stripes corresponding to one line in one of said two sets of parallel lines;

said membrane sections comprises a second plurality of narrow membrane sections, each narrow membrane section corresponding to one line in the other of said two sets of parallel lines; and

said logic control means comprises:

means for generating in a predetermined sequence a first set of electrical signals indicative of the elements in the matrix to be displaced to form the desired character, said first predetermined sequence of electrical signals being applied to the narrow membrane section containing the element to be displaced in a like sequence;

means for generating in a predetermined sequence a second set of electrical signals applied to said conductive stripes, said second set of signals applying to each conductive stripe an electrical signal hav ing a potential approximately equal to potential of said one output while simultaneously applying to all other conductive stripes said other output from said source of electrical power, further, wherein said first and said second set of electrical signals are synchronously generated to apply both sets of signals to each element in the matrix, in a predetermined order.

38. The display panel system of claim 37 wherein said multi line element matrix is a five by seven element array arranged in the form of a parallelogram.

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Classifications
U.S. Classification345/48, 359/292
International ClassificationG02F1/133, G02F1/13, G09F9/37
Cooperative ClassificationG09F9/372
European ClassificationG09F9/37E