EP1992496A1 - Writing board with EL illumination element and manufacturing method with application - Google Patents

Abstract

On a flexible substrate (3) underneath there is a conductive structure (17) along with a power supply (6) and operating electronics (8) including an on-/off-switching system (7) and a charging system (9). A polymer foil (18) on top and the flexible substrate underneath are welded with a positive fit around the edge with a thermoplastic (15). An independent claim is also included for a method for producing a writing board/noticeboard.

Description

The invention relates to a writing board with EL lighting element and a manufacturing method and application.

In the US05083242 Piotrowski ("Illuminated underwater writing tablet", Published / Filed: 1992-01-21 / 1991-02-19) discloses an illuminated underwater writing tablet in which light can be introduced at one edge via a chemically activated light rod , This system is by no means based on a zinc-sulfide electrophilitic EL EL thick-film AC film and also has no electrically chargeable properties. The use of a chemoluminescent light rod has the disadvantage that only a low luminance is given with a short light duration.

In this arrangement, therefore, there is the disadvantage that it is not a flat light source, but to selectively existing light-emitting diodes, which illuminate the surface to be illuminated only in reflected light.

In the cited document therefore has the disadvantage that initially the power source is arranged separately from the lighting board, which is associated with increased effort. As a result, the user of the lightning board has to strap the power source and associated electronics to a belt, and the wires that make up the electrical connection to the writing board are a major obstacle to working with the writing board.

In addition, the entire assembly is not protected against moisture, because the electronics and the intervening wires can fail when exposed to moisture or damage impacts.

Another disadvantage is that only a light impression is delivered up, but it is not provided that the light source also radiates down.

In the US05163748 , Messinger ("Illuminated clipboard", Published / Filed: 1992-11-17 / 1992-02-14) is called an illuminated terminal board, beem in the area of the terminal board illuminants are arranged such that the surface of the terminal board is illuminated. In this system, no area zinc-sulfidic electroluminescent EL thick-film AC film is called and the illumination is not from the bottom but with incident light.

In the US05381310 Brotz ("Sheet-illuminating system", Published / Filed: 1995-01-10 / 1994-04-08) is called a lighting apparatus for reading and / or writing on a sheet in little or no light using an electroluminescent film. In this case, the EL film is arranged in a recess of the terminal board. It is therefore not an EL film directly formed as a clipboard, but used in conjunction with a clipboard, which avoided in the new present invention by the integral lamination-technical design of the EL film with the form-fitting molded (molded) boundary including the embedding of the electronic components becomes.

In the US06951403B2 , LightWedge ("Device for illuminating a generally flat surface", Published / Filed: 2005-10-04 / 2002-04-23) is called a lighting device for a generally flat surface, wherein in a unit having a photoconductive element at one edge Light is coupled in from a light source and is coupled out flatly. It will be in this US06951403B2 So called by no means a flat EL-film, but a light source, which acts on an edge of a photoconductive element with light, which is then decoupled over the flat surface.

Consequently, in the cited document, there is the disadvantage that no two-dimensional light pressure is achieved and, moreover, only an uneven light distribution is provided.

In the EP00751340B1 Lumitex ("Light-emitting panel assemblies", Published / Filed: 2000-05-24 / 1996-06-25) discloses a light-emitting plate assembly wherein light is coupled in at an edge and light is flat is decoupled. In this EP00751340B1 Thus, in no way is a flat EL foil called, but a light source which acts on an edge of a light-conducting element with light, which is then decoupled over the flat surface.

In this document, therefore, there is the same disadvantage as he is based on the US 6951403 B2 was mentioned.

The invention is therefore the object of developing a writing board so that it completely splash-proof under the most difficult conditions even under the influence of mechanical shocks a uniformly distributed luminous impression allows, the light source should shine both up and down.

To solve the problem, the invention is characterized by the technical teaching of claim 1.

An essential feature of the invention is that now according to the invention all parts are integrated in the board itself and are housed there so that they are splash-proof and arranged damage.

For this purpose, for example, an inductive charging station, which now makes it possible for the first time that no ohmic contacts are accessible from the outside.

Another advantage is that now according to the invention it is also provided that the side facing away from the luminous surface of the writing board (underside of the writing board) is transparent. This results in the decisive advantage that the light impression is directed both forward towards the sheet to be described as well as to the rear towards the bottom of the board, so that with the writing board and the surrounding area can be illuminated. In this way, the writing board can be found very easily, if they z. B. on a place has been placed or stored, without it is always necessary to put the board with its front side up.

In smoker-filled environments, as they are typical for disaster operations, therefore, the writing board can be found very easily and very easily operated.

The encapsulation of the writing board, which is also flexible in itself, thus results in a completely splash-proof, evenly luminous writing board, which still works and can be used even in smoker-filled environment and under spray water. This can not be deduced from the prior art.

Some embodiments of the invention are described below with reference to the drawing figures.

• Figur 1 : eine schematische Darstellung einer beispielhaften Schreibtafel (1) mit EL-Leuchtelement (2) mit eingeklemmten Schreibblatt (4) und Schreibstift (5) in Draufsicht,
• Figur 2 : einen schematischen Schnitt durch eine beispielhafte Schreibtafels mit EL-Leuchtelement (2) mit eingeklemmten Schreibblatt (4) und Schreibstift (5),
• Figur 3 : einen schematischen Schnitt durch ein beispielhaftes EL-Leuchtelement (2).

Showing:

• FIG. 1 : a schematic representation of an exemplary writing board (1) with EL luminous element (2) with pinched writing sheet (4) and pen (5) in plan view,
• FIG. 2 FIG. 2 : a schematic section through an exemplary writing board with EL luminous element (2) with clamped writing sheet (4) and writing pen (5), FIG.
• FIG. 3 : A schematic section through an exemplary EL luminous element (2).

In FIG. 1 is a schematic representation of an exemplary writing board (1) with EL light-emitting element (2) with pinched writing sheet (4) and pen (5) shown in plan view.

The EL light-emitting element (2) is produced according to the prior art by screen printing of EL pastes, ie in thick film technology, and with Alternating current of a few 100 to over 200 volts and a frequency greater than 50 Hz and typically in the range 400 Hz to 800 Hz and operated at high emission brightness values also above.

Since such EL lighting element (2) must be flexibly deformable in use as a writing board (1) and should be used under harsh operating conditions, the EL element (2) design is designed for high ductility. In particular, polyurethane-based screen printing ink systems are used and a bendable embodiment is selected at least for the front transparent electrode.

In this case, intrinsically conductive polymers, for example based on Baytron P, can be used or it is possible to disperse polymeric thin and substantially transparent and electrically conductive layers based on ITO (indium tin oxide) or ATO (antimony tin oxide) particles be used in a polymeric matrix. In addition, SWCNTs (single-walled carbon nanotubes) can be added and thus the risk of cracking due to overstretching or excessive deformation can be reduced or avoided.

Basically, a sputtered ITO electrode can be used and in this case the entire system must be made much stiffer, since too small bending radii or excessive deformation such ITO electrode tends to crack and thus a failure of the EL light field (2 ) or parts thereof.

Usually, such transparent front-side electrodes with surface resistance values of about 30 ohms / square to 60 ohms / square to 600 ohms / square are still edged with a so-called bus bar and can thus produce a uniform EL luminous field with dimensions of typically A5 up to A4 or B4 become.

The EL light-emitting element (2) is usually produced from at least one front transparent film of PET or polycarbonate (PC) with a film thickness of typically 125 μm or 175 μm and above. The outside of this film is the title block (12) and may have a corresponding surface structure. A matt or semi-gloss surface texture provides good scratch resistance and acts as a diffuser for EL emission. Basically, this upper transparent film can also consist of two films and this second film can be formed by means of lamination and thus an additional protection can be achieved.

On the inside of this front transparent film, a largely transparent and electrically conductive layer with peripheral bus bar is arranged or a graphic design (13) can be arranged. Subsequently, the EL layer of usually microencapsulated zinc sulfide electroluminophores is homogeneously dispersed in a polymeric matrix, preferably based on polyurethanes and such permanently elastic polymers arranged.

The EL layer can have a desired emission color by selecting or mixing the EL pigments. It is also possible to incorporate color-converting dyes and / or pigments (Stokes shift) and, for example, the emission color white can be achieved in this way. Since such conversion admixtures usually have an intrinsic color in the range rosy-pink to orange, a thin layer of, for example, titanium dioxide dispersed in a polymeric matrix can be arranged above it, and thus an off-white surface can be achieved.

In one development of the present invention, in the EL layer or in the polymeric matrix it is additionally possible to add long luminescent pigments. For a rapidly rechargeable afterglow layer, inexpensive zinc sulfidic persistence pigments can be used, and for a slower rechargeable afterglow layer, preferred are rare earth doped aluminates or silicates pigments which then has an afterglow time of up to 2,000 minutes (observable for the dark-adapted eye and fully charged persistence pigments) and above.

Often, mixtures of these mentioned afterglow pigments are used. The emission color is from greenish-bluish-yellowish to blue and red selectable, per pigment, the persistence varies widely. The advantage of this Nachleuchtpigmentebeimengung may lie in the fact that even if the power supply fails, the title block (12) remains lit, but usually only a few mcd / m ² and not some 2 to 10 cd / m ² as in the case of the function of the energy supply EL lighting field.

The EL layer is usually produced by screen printing. By this type of production also point-like EL elements are basically printable. By such a grid of EL points or small geometrical shapes, the active EL area can be reduced and the EL power supply can be made smaller. Furthermore, the entire writing board (1) can also be designed to be translucent and in the embodiment with a substantially transparent rear side (3, 17) an increased transparency of the entire writing board (1) can be achieved by the formation of grid-like EL elements.

After the insulation layer or the usually two printed insulation layers comes the back electrode. This can be carried out integrally depending on the embodiment in transparent-translucent form or non-translucent form, ie directly in connection with the insulating layer or separated by means of lamination of a corresponding electrode arrangement.

The back electrode may be integrated in the EL layer sequence (2) or may be formed by the backside conductive pattern (17) on the substrate (3).

The substrate (3) can in turn be an integral part of the EL light-emitting element (2) or an independent component.

The substrate (3) may be formed in the form of a thin circuit board having a wiring pattern (17). However, it is also possible to choose a substantially transparent polycarbonate film (PC film) or a film of ABS and the like of polymeric materials. In this case, the conductive structure can be produced by printing technology or embossing technology or wire laying technology.

The components (6, 7, 8, 9) are arranged on this substrate (3). The wiring or wiring of the components via the conductive structure (17), wherein the electrical contacting can be done by means of conventional soldering, laser soldering, welding, ultrasonic welding, electrically conductive bonding and the like connection technologies.

The individual components are positioned using adhesive technology or US technology and can still be protected by means of resin systems and dispenser application and thus protected for the subsequent injection molding process.

As the power supply (6), a rechargeable battery is preferably used, and relatively small or flat batteries having a good charging characteristic and a low discharging characteristic can be used. Modern EL inverters can be operated from 3 volts DC and require low currents.

The on-off switch (7) or button can be realized in a variety of ways and can be formed for example as a capacitive field or as a flexurally elastic field and thus meets the requirement for splash water protection.

The operating electronics (8) include the EL inverter, so the electronic circuit that converts a DC voltage from the battery (6) into an AC voltage of typically 100 to over 200 volts and 50 Hz to typically 400 Hz and into the kHz range. For small EL arrays, extremely small chip inverters can be used, which often include ancillary equipment for operation of two EL arrays, or power-down electronics or sensor-controlled brightness control.

In the operating electronics (8) further the type of charging of the battery (6) is formed. In FIG. 1 an inductive charging system (9) using a coil (10) and a hole (11) or a recess for the inductive charging system is outlined. Such a system is designed million times in electric toothbrushes. Basically, however, ohmic contacts can also be led out and these can be supplied with a low voltage for charging the battery (6). The electrical contacts may be formed as metallic non-oxidizing surfaces or commercially available charging sockets may be used for DC low voltage.

The molded bordering plastic (15) can be produced by means of injection molding or can also be designed in a two-part design.

In this case, preferably permanently elastic plastics, for example thermoplastic polyurethanes (TPU) with the trade name Desmoflex® from Bayer MaterialScience or thermoplastic elastomers (TPE) based on Karton® (Kraton Polymers LLC) and the like thermoplastics are used.

The two-part design plastic version (15) can be formed such that in the upper region of the electronic components (6, 7, 8, 9) or in the connection region of the EL film (2) a separate covering injection molding element is produced and this with the surrounding injection molding element is connected.

In all cases care should be taken to ensure that the writing board (1) meets the requirements for splash water protection and complies with Directive 94/9 / EC (Atex 95) for explosion-proof equipment and can be used in damp, foggy and potentially explosive atmospheres.

The clamping device (16) can be formed together with the bordering plastic element (15), wherein the production as a two-part plastic element has certain manufacturing advantages. However, the clamping device (16) can just as well be formed as an independent plastic element or as a metal part connected to the plastic element (15). The function is such that the clamping part (16) is intended to hold or clamp a writing sheet (4). In principle, the clamping device (16) can also be formed only one piece at a time or several times at one or more edges of the writing board (1). In addition, the bordering plastic (15) can cause a holding function by means of fine undercuts.

The writing sheet (4) is held on the writing field (12) by means of a clamping device (16) and the user can write a note (14) or a record or notes on the writing sheet (4) by means of a writing pen (5). Depending on the field of application, the writing sheet can be made water-resistant and the note (14) also has a water resistance. In order to be able to design a protocol (14) better, the EL lighting element (2) or the title block (12) can be provided with a graphic design (13) which contains corresponding entry fields and thus supports the logging.

In FIG. 2 a schematic section through an exemplary writing board with EL light element (2) with pinched writing sheet (4) and pen (5) is shown.

In this schematic representation of the integrally formed bounding plastic (15) is shown in one piece and is the clamping device (16) shown integrally molded with the plastic (15). In this respect, the comments regarding two-part training and the use of various plastics or metallic clamping elements apply as in the description of FIG. 1 noted.

In FIG. 3 a schematic section through an exemplary EL light-emitting element (2) with substrate (3) and the components (6, 7, 8, 9, 10, 11) is shown.

In this schematic section, an exemplary embodiment of the EL light-emitting element (2) with a rear-side substrate (3) and the rear-side conductive structure (17) is shown. The components (6, 7, 8, 9, 10, 11) are shown only schematically in the upper region and can in principle also be arranged on the other edges or on the back of the substrate (3).

LIST OF REFERENCE NUMBERS

1

Writing board with EL light element

2

EL luminous element: zinc sulfide particulate thick film AC planar EL luminous element

3

Substrate: back sheet element

4

Writing sheet: transparent or translucent and water-resistant and writable

5

pen

6

Power supply: rechargeable battery and the like

7

On-off switch or button

8th

Operating electronics: EL inverter and charging electronics and optional brightness sensor with dimmer electronics or power-down electronics

9

Charging system: inductive charging system with coil and hole or ohmic contacts (not drawn) or capacitive coupling (not shown)

10

Coil of the charging system

11 1

Hole or recess for the inductive charging system

12

Title Block

13

Graphic design

14

Note or protocol or notes

15

Molded bordering plastic

16

Clamping device: integrally formed in the molded plastic or a Einlegefederelement made of metal or plastic

17

Back conductive structure

18

Upper transparent polymer film

Claims (12)

Writing board (1) having at least one sheet-like particulate thick film AC EL luminous element (2), said EL luminous element (2) having at least an upper transparent polymeric film (18) and said writing board (1) having a lower flexible substrate (3) and on this lower substrate (3) a conductive structure (17) is arranged and the power supply (6) and the operating electronics (8) including the at least one on-off switching system (7) and the charging system (9) are arranged there and the upper polymeric film (18) and the lower substrate (3) are molded in a peripheral manner with a thermoplastic material (15) in a form-fitting manner, and in this way the writing board (1) is at least splash-proof. Writing board (1) with at least one EL lighting element (2) according to claim 1, characterized in that the charging system (9) consists of a coil (10) and the molded plastic (15) forms an opening (11) or depression and this Opening (11) is arranged during electronic charging via the mandrel of a charger and thus the charging process is carried out and the writing board (1) with the molded plastic (15) forms a generally form-closed design into which no splashing can penetrate and the Directive 94 / 9 / EC (Atex 95) for explosion-proof equipment. Writing board (1) with at least one EL light-emitting element (2) according to claim 1, characterized in that the charging system (9) consists of at least two ohmic contacts, which are at least splash-proof and corrosion-resistant led by the molded plastic (15) to the outside and can be connected during charging by a suitable electrical contact with the charger and thus the writing board (1) is designed splash-proof and complies with the directive 94/9 / EC (Atex 95) for explosion-proof equipment. Writing board (1) with at least one EL lighting element (2) according to claim 1 to 3, characterized in that the writing board (1) at least piecewise a clamping device (16) for a writing staff (4) and this clamping device (16) consists of a metallic spring element is formed or integrally formed by the molded plastic. Writing board (1) with at least one EL luminous element (2) according to claim 1 to 4, characterized in that the EL luminous element (2) has an emission color white or a fluorescent signal color and in the brightness manually and / or automatically to the ambient brightness can be adjusted. Writing board (1) with at least one EL light-emitting element (2) according to claim 1 to 5, characterized in that a plurality of EL light elements (2) or a plurality of EL light fields (2) are formed on the title block (12) and this a different Have emission color. Writing board (1) with at least one EL light-emitting element (2) according to claim 1 to 6, characterized in that the at least one EL light-emitting element (2) is additionally equipped with phosphorescent pigments luminescent and thus the writing field even in case of failure or when consumed Battery luminescent. Writing board (1) with at least one EL light-emitting element (2) according to claim 1 to 7, characterized in that the lower substrate (3) including the lower conductive structure (17) is transparent or semitransparent formed and in such a way the writing field in addition to a light emission below. Writing board (1) with at least one EL luminous element (2) according to claim 1 to 7, characterized in that the lower substrate (3) is opaque and the layer below the EL thick film layer is reflective or opaque white. Method for producing a writing board (1) with at least one flat particulate thick film AC EL lighting element (2) according to Claims 1 to 9, characterized in that the at least one EL lighting element (2) is produced according to the prior art, wherein in addition, the power supply (6) and the operating electronics (8) including the at least one on-off switching system (7) and the charging system (9) on the lower substrate (3) are arranged and then this unit in an injection molding tool with the molded edge Plastic (15) is provided. Method for producing a writing board (1) with at least one EL luminous element (2) according to claim 10, characterized in that the molded plastic (15) has elastomeric properties. Application of a writing board (1) having at least one flat particulate thick film AC EL lighting element (2) according to claim 1 to 9, prepared according to claim 10 to 11 as a clipboard or signal board, with a water-resistant pen (5) directly on the Writing field (12) or preferably on a water-resistant writing sheet (4) arranged thereon can be written and the writing sheet (4) and / or the writing field (12) can have a graphic design (13) and such a protocol (14) can be filled or general notes (14) can be recorded and so in operations of the fire department, the rescue, the police, the military and the like uses under bad to lack of lighting or fog-like or hazardous environment is usable.

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