EP1152643A1 - Display having at least a luminescent surface - Google Patents

Abstract

Display has a connecting layer (3) and layers of an electroluminescent lamp arranged on a supporting conductor plate. The connecting layer is either an electrically conducting layer, preferably isotropic in the direction of the layer thickness or a layer having a high dielectric constant, preferably more than 3.5. The lamp comprises a partially transparent support layer (4) provide with a transparent electrically conducting covering electrode layer (6) and a phosphorus layer (7) provided underneath. Preferred Features: A dielectric layer (10) having a light reflection property is arranged between the connecting layer and the phosphorus layer.

Description

The invention relates to a display device with at least one electroluminescent surface, being on a supporting circuit board a connecting layer and the layers of the EL lamp arranged thereon are.

Such display devices are preferably electronic components with integrated graphical electroluminescence (EL) displays based on inorganic thick film systems. EL foils are usually used for backlighting LCD's and the like used. Because inorganic thick film EL systems at relatively high AC voltages of typically 100 to 200 volts (RMS) and several 100 Hz, typically 400 Hz must be operated up to a few kHz, were and are displays with a large number of small EL areas difficult in the electronic control, because the Secondary side of a conventional EL inverter, that is, the relative high AC voltage, must be switched.

Novel electronic semiconductor components now make this possible and therefore the large number of EL capacitors must be connected or to wire.

Modern printed circuit boards are ideally suited as a wiring element.

Since 1936, Destriau has been based on electroluminescence (EL) high alternating voltage field on ZnS phosphor powder with manganese and / or Known copper doping, and today there are various first and other coactivators to increase brightness and life used. In particular, various microencapsulation technologies from metal oxide and silicon nitride to multiple aluminum oxide layers used.

To achieve high brightness values and a long service life, is it is known to generally have relatively large pigments in the range of 15 up to 30 and up to 50 microns in diameter what the Processing in screen printing somewhat difficult and especially the Homogeneity of an EL encoder is impaired.

In US Pat. No. 2,838,715, an EL lamp based on a Glass plate with a transparent, electrically conductive coating described. Another training was in U.S. Patent 3,315,111 called. An electroluminescent display light-emitting capacitor has already been used in the DT-PS 2012803 in the form of a 7-segment element on one Called glass substrate and was already the screen printing process applied. U.S. Patent 4,927,490 and U.S. Pat US Pat. No. 4,839,558 was a printed circuit board as a carrier and wiring element described in connection with a glass EL element. According to US 5,131,877 was an EL display with a segment display and one Plenty of EL fields shown, with a variety of holes in an insulation layer for electrical through-plating electrically conductive screen printing paste can be used to such Large number of EL fields and electrodes to be wired or wired.

The US Pat. No. 5,156,885 is cited only by way of example, in which methods for microencapsulation of typical ZnS phosphors.

In DE-OS 40 23 693 (Moser) is a display device with Electroluminescent lighting described in a circuit board is used as a base electrode. The connection of the transparent and electrically conductive display page with the Luminescent pigments or with a dielectric and "binder" is disadvantageous, however. US Pat. No. 5,244,750 describes EL lamps described the special copper and manganese activated zinc sulfide phosphor pigments with a microencapsulation based on aluminum oxide use and such a high brightness with long life cause. In US Patent 5,667,417 and in US Patent 5,720,639 a Method of making EL lamps called and a technology used, which comes from the flexible circuit board industry, whereby Metal foils are etched and the like structured so that they serve as the base electrode for further EL capacitor construction, and so inexpensively a variety of EL lamp elements in one Roll processes can be produced. In US 5,620,348 a Method of manufacturing EL lamps with transflective front electrodes as well as special other light-coupling effects called. In US Pat. No. 5,593,782 one with a very thin Oxide film encapsulated electroluminescent phosphor and its Manufacturing processes described by vapor phase hydrolysis and the Advantages in terms of high brightness and long life shown. JP-PS 11260561 describes an EL lamp in which the transparent electrically conductive layer produced by screen printing will also be called color converting admixtures.

The present invention comes from the above-mentioned DE-OS 40 23 693 (Moser) closest in structure.

The present invention has for its object a display device with electroluminescent lighting based on inorganic To create AC thick film systems, the Layer structure on a carrier substrate by means of printing processes such as Screen printing or offset printing in large quantities with the necessary Precision can be made. The light output should be high and the control of a large number of light fields should be connected can be kept compact with the associated electronics.

The present invention is characterized in that the Connection layer either one, preferably anisotropic in the direction of the Layer thickness, electrically conductive layer or a layer with high Dielectric constant, preferably> 3.5, and that the EL lamp comprises an at least partially transparent carrier layer, the inside with a transparent, electrically conductive cover electrode layer and underneath is provided with the phosphor layer.

Further advantageous features of the invention are the following Description, the claims and the drawings.

In the following the invention will be described in several embodiments Hand described in the drawings. Fig. 1 to Fig. 4 are schematic Representations of the cross section through the device. Figures 5 and 6 show top view and section through a device for displaying the Contacting the busbar from the circuit board to the cover electrode layer. The layer thicknesses are not drawn to scale.

In all embodiments, the device comprises one of several Layers of existing EL lamp 1, the circuit board 2 and in between horizontal connecting layer 3 EL lamp 1 and the circuit board 2 separately manufactured and connected to one another by means of the connecting layer 3.

The EL lamp 1 comprises at least partially as a carrier substrate transparent carrier layer 4, for example a thermoplastic Is plastic film. The overlying decorative layer 5 is used graphic design of both the illuminated and the non-illuminated Surface sections. On the underside of the carrier layer 4 is used to form a transparent, electrically conductive cover electrode the lid electrode layer 6 is arranged. It is about preferably a so-called ITO (indium tin oxide) layer or a NON-ITO layer or a conductive polymer coating that acts like an ITO layer and in which the expensive indium passes through other substances is replaced. Appropriate products from the companies DuPont, Agfa and Technoplast are referenced. Below the lid electrode layer 5 is the phosphor layer as the electroluminescent layer 7 arranged. This contains the schematically indicated electroluminescent particles 8, when excited by a corresponding alternating field light rays 9 in the visible range radiate. If one speaks of phosphor layers here, means this is not the presence of phosphorus, but encompasses all applicable electroluminescent substances. The EL lamp is down 1 completed by a dielectric layer 10, the light reflecting Has properties.

As described later, the decorative layer 5 can also be below the carrier layer 4 lie. The EL lamp 1 can also go down a counter electrode 18 must be completed.

The printed circuit board 2 has 11 guide surfaces 12 on the inside e.g. consist of copper and their surface shapes e.g. according to known Etching processes can be produced. Contact elements 13 protrude through the printed circuit board 2 and connect the guide surfaces 12 with conductor tracks 14 on the component side 15 of the printed circuit board 2. On the component side 15 are those for the control and power supply of the Device required electronic components 16 arranged.

The cover electrode layer 6 is by means of a not shown here Connection line (busbar) with the electronics on the Printed circuit board 2 connected.

The EL lamp 1 is on the printed circuit board 2 by means of the connecting layer 3 connected. This can be a corresponding adhesive film or also consist of a liquid adhesive. The tie layer has a high dielectric constant, preferably> 3.5 and particularly preferably between 30 and 50.

When attached to one or more of the baffles 12 and to the lid electrode layer 6 AC voltage is applied, there is an excitation of the alternating electroluminescent particles 8 and for emitting the light rays 9. The alternating field is dashed indicated at 17.

The geometric dimensions of the guide surfaces 12 determine the geometric dimensions of the luminous surfaces. The individual layers of the EL lamp 1 are preferably applied to the carrier substrate using the screen printing method. However, other printing methods such as offset printing can also be used. Typical layer thicknesses for the backing layer 4 are 175 μ m, for the decorative layer to 30 μ m, for the cover electrode layer 6 in the case of conductive polymer coating or ITO-sputtered layers <1 μ m and in the case of ITO or NON-ITO pastes> 1 μ m for the phosphor layer 7 approximately 30 μm , for the dielectric layer approximately 10 μm . About 62.5 μm can be assumed for the thickness of the connecting layer and the printed circuit board 2 usually has a thickness between 300 μm and 1.6 mm. The dielectric layer 10 shown in FIG. 1 is optionally arranged and has a high relative dielectric constant of more than 3.5 and typically between 30 and 50. Layer thicknesses between 10 and 20 μm are preferred. To avoid pinholes, careful printing is necessary and this layer can also be formed by printing twice. Furthermore, it is advantageous if the dielectric layer 10 has good reflection of the electroluminescent light. Advantageous materials for the carrier layer 4 are, for example. PET, PET-G, PC, PVC and PMMA. Layer thicknesses of 50 to 500 μm , preferably 175 to 250 μm, are proposed. This carrier layer enables a high degree of flexibility for the end product and thus also 3-dimensional shapes. However, other materials such as eg. Use glass.

Rigid and or flexible and / or Multilayer boards are used. Soldering the electronic Components on the component side 15 of the circuit board can Appropriate techniques are also used after the application of the EL lamp 1 done, e.g. using so-called reflow soldering or conductive adhesive, avoiding disruptive temperatures.

The plated-through hole by means of the contact elements 13 allows the necessary conductor tracks and electronic components on all sides to accommodate the circuit board 2, while on the inside 11 only the guide surfaces 12 housed as electrodes or contact points Need to become. Here is a compact structure of the device possible.

As described, a preferred feature of the invention is the counter electrodes to be controlled from the circuit board and the cover electrodes on the other side of the EL layer. According to Fig.1 the counter electrode is formed directly on the surface of the circuit board, wherein the tie layer has a high dielectric constant having.

In the preferred exemplary embodiment according to FIG. 2, the guide surfaces act 12 not directly as counter electrodes, they are Counter electrodes 18 part of the EL lamp 1. For this purpose, for example. by means of Screenprint a corresponding layer of silver paste or another conductive printing paste can be printed on. The electrical line from the guide surfaces 12 on the counter electrodes 18 is here in a Z direction anisotropically conductive connecting layer 3 accomplished. The alternating field thus acts between the counter electrode 18 and the Cover electrode 6. Otherwise, the design of Figure 2 corresponds to that the Figure 1 and the reference numerals each refer to the same or analog features.

The anisotropically conductive connecting layer 3 in the Z axis can, for example. by 3M films of types 7303 and / or 9703 are formed.

As an alternative to arranging anisotropic conductive adhesive layers it is also possible within the scope of the invention by means of printing processes to arrange isotropically conductive connecting layers in sections such that only in those areas the isotropically conductive connecting layers are arranged where the electrical line is to take place.

The particular advantage of the embodiment according to Figure 2 is that a exact positioning of the counter electrodes can be achieved and the entire network retains its flexibility and flexibility. The dielectric layer here consists of two layers 19.20, as one corresponds to double printing.

3 shows that the layer structure can also be done more easily, for example by. in execution the dielectric layer is omitted according to FIG. The Phosphor layer and the cover electrode layer 6 arranged above it are not arranged continuously, but in sections, as the Illuminated surfaces of the device should correspond.

4 are the counter electrodes 18, the EL layer 7 and the cover electrode layer 6 arranged in sections. The dielectric layers 19, 20 are continuous.

Here, the decorative layer 5 lies below the final carrier layer 4, which gives a higher abrasion resistance of the surface can be. The outer surface of the carrier layer 4 can be used for anti-reflective treatment for example, be matted or optically designed differently.

A possible variant for the power supply is shown on the left in FIG the lid electrode, usually via a bus is constantly under tension. The power supply comes from the guide surface 21 through the connecting layer 3 to a Contact layer 22, and from there to the connection point 23 of the cover electrode layer.

5 shows the top view of the device with schematic drawn light fields 24. The top layer of the EL lamp 1 here is the decorative layer 5. A bus bar 25 is used to connect the Cover electrode layer 6 with a connecting contact 26 on the front or component side of the circuit board 2, as shown in Fig.6. The busbar can have a flag 27 as an extension as a carrier substrate the carrier layer 4, on which a track 28 for power conduction the lid electrode layer is printed. With the screw 29 the busbar fixed. This contact device can be omitted if the Contact is made directly through the connecting layer, as in Fig. 4 is shown on the left.

The following workflows for producing devices according to the invention Examples include:

Workflow EL lamp with circuit board

• Screen printing of various translucent, glazing or opaque colors for graphic design of the application-specific interface
• as front screen printing with ITO sputtered materials (PET, PO, glass, etc. ...)
• As a back pressure for structured materials and / or not ITO sputtered materials when using ITO or NON-ITO pastes
• Screen printing of a semi-transparent layer (Deathfront), for Contrast and for better visibility of partial / structured EL surfaces in the ON / OFF state
• Screen printing of a barrier layer when using ITO or NON-ITO Pastes
• Screen printing of an etching resist, etching and again removing the etching resist, when using ITO sputtered materials and the Need for better arrest later printed layers or for the electrical isolation of different EL lamps (matrix)
• Screen printing of an ITO or NON-ITO paste or organically conductive polymer coating
• Screen printing of a busbar made of conductive silver paste to increase the Guide values of ITO or NON-ITO paste
• Screen printing of a flat phosphor layer and / or several, structured phosphor surfaces in one or more colors Structuring of different illuminated areas
• Screen printing of an insulation layer with the second function as reflector

OPTION A

• Screen printed a second layer of insulation to prevent short circuits between to avoid the coarse-grained phosphorus and the back conductive layer
• Screen printing of the rear conductive layer, the areas of which are the later Lamp area describes, simultaneous pressure of the busbar, the Contact to the bus bar in front by one or more Exemptions in the insulation is made
• Flat lamination of the anisotropic adhesive under pressure and / or temperature
• Laminating the previous network onto an already assembled one single-sided, double-sided printed circuit board or multilayer or flexprint

VARIANT B

• Screen printing of a second insulation layer, on a printed circuit board, the surfaces of which the later EL lamp describes and
• Collection of the previous network with the still wet Print layer on the circuit board with subsequent drying under Pressure or
• Gathering the previous bond with the dried print layer on the circuit board with subsequent pressing under Pressure and temperature
• A tab is punched out to contact the busbar Bent 180 degrees and mechanical with the back of the circuit board is connected (e.g. screwed when assembling the circuit board).

VARIANT C

• Flat lamination of a double-sided adhesive film and / or Adhesive with high, relative dielectric constant under pressure and / or temperature
• Laminating the previous network onto an already assembled one single-sided, double-sided print plate or multilayer or flexprint
• A tab is punched out to contact the busbar Bent 180 degrees and mechanical with the back of the circuit board is connected (e.g. screwed when assembling the circuit board).

With variants B and C, the copper surface of the circuit board represents the Counter electrode of the capacitor (EL lamp). This is in Series represent a less expensive option, but represents the Manufacturing technology has significantly higher demands in terms of Precision, as attention is paid to the plane-parallel electrode spacing got to.

The connecting layer does not have to be applied over the entire surface, as in the Figures shown, but can also be in their conductive form partially applied to establish the electrical connection to the To produce counter electrodes 18.

Claims (14)

Display device with at least one electroluminescent surface, wherein a connecting layer and the layers of the EL lamp are arranged on a supporting printed circuit board, characterized in that the connecting layer (3) either one, preferably anisotropically in the direction of the layer thickness, an electrically conductive layer or a layer with a high dielectric constant, preferably> 3.5, and that the EL lamp (1) comprises an at least partially transparent carrier layer (4), the inside of which has a transparent, electrically conductive cover electrode layer (6) and below that the phosphor layer (7 ) is provided. Display device according to Claim 1, characterized in that a dielectric layer (10, 19, 20) with a light reflection property is provided between the connecting layer (3) and the phosphor layer (7). Display device according to claim 1 or 2, characterized in that on the inside (11) of the printed circuit board (2) as counter-electrodes there are guide surfaces (12) and that the connecting layer (3) is a layer with a high dielectric constant, preferably> 3.5. Display device according to claims 1 or 2, characterized in that the guide surfaces (12) are assigned counter-electrode layers (18) which are arranged on the layers of the EL lamp (1) and in that the connecting layer (3) between the guide surfaces (12) and the counter electrodes are electrically conductive, preferably anisotropically in the direction of the layer thickness. Display device according to claims 1 to 4, characterized in that the phosphor layer (7) and the counter electrode layer (s) (18) on the cover electrode layer (6) are arranged over the entire surface or in sections, preferably between the phosphor layer (7) and Counter electrode layer (18) one or more dielectric layers (10, 19, 20) are provided. Display device according to one of claims 4 or 5, characterized in that the counter electrode layer (s) (18) are printed with electrically conductive printing paste. Display device according to claims 1 to 6, characterized in that the layers are printed on the carrier layer (4) using the screen printing method. Display device according to claims 1 to 7, characterized in that the connecting layer (3) is an anisotropically electrically conductive adhesive film. Display device according to claims 1 to 8, characterized in that the carrier layer (4) is a film made of thermoplastic material such as PET, PET-G, PC, PVC or PMMA and a thickness of 50 to 500 µm . preferably has 175 to 250 μm . Display device according to claims 1 to 9, characterized in that the cover electrode layer (6) is an ITO layer, a NON-ITO layer or a transparent conductive polymer layer. Display device according to claims 1 to 10, characterized in that the carrier layer (4) is graphically designed on the outside or inside in screen printing or offset printing. Display device according to claims 1 to 11, characterized in that the cover electrode layer (6) is supplied with voltage from the printed circuit board (2) via a busbar (track 28), or in that an electrical line is provided through the connecting layer (3). (Fig.4) Display device according to Claims 1 to 12, characterized in that the busbar (25) is formed as a flag (27) which is brought up to the side of the EL lamp 1 and has a conductive path (28) which can be contacted with the printed circuit board (2). The display device according to claims 1 to 13, characterized in that the dielectric layer (10,19,20) has a thickness of preferably 10 to 20 μ m and a dielectric constant of> 3.5, preferably comprising between 30 and 50 and preferably produced by two-time print job is.

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