EP1733596A2

EP1733596A2 - Electroluminescent display

Info

Publication number: EP1733596A2
Application number: EP05716528A
Authority: EP
Inventors: Manfred Hartmann
Original assignee: Schreiner Group GmbH and Co KG
Current assignee: Schreiner Group GmbH and Co KG
Priority date: 2004-04-05
Filing date: 2005-04-04
Publication date: 2006-12-20
Anticipated expiration: 2025-04-04
Also published as: WO2005098891A2; US7872416B2; WO2005098891A3; ATE394905T1; US20070284992A1; DE102004016709A1; DE502005004002D1; EP1733596B1

Abstract

An electrode layer (2) formed by a transparent conductive varnish is applied to a mineral or plastic glass carrier. Afterwards, a luminescent layer (3) formed by a transparent matrix (5) provided with electroluminophors (4) incorporated therein is disposed within contours defining an image surface. Said luminescent layer (3) is dividable into several discrete partial areas. A rear silver-containing electrode layer (7) extends within the a luminescent layer (3) contours above a surface whose size is approximately equal to the size of the luminescent layer (3) but leaves a narrow edge area (8) thereof free. The structure also comprises an insulating transparent layer (9) provided with recesses (10) in the area of the rear electrode layer (7) in order to bring it into contact for voltage supply from a rear face. Said rear electrode layer (7) is brought into contact through the recesses (10) of the insulating layer (9) by means of a transparent conductive varnish contact layer (12). The inventive electroluminescent display is insulated on the rear face thereof by a rear transparent insulating layer (14).

Description

electroluminescent display

The present invention relates to an electroluminescent display.

An electroluminescent display (EL display for short) is understood to mean a flat body which, at least in part, has at least one electroluminophores embedded in a binder matrix, i.e. by means of excitation by means of an electric (alternating) field has luminous substances containing a luminous layer. EL displays are used in particular as advertising signs with illuminated picture areas. In addition, there are numerous other applications such as display boards, displays, decorative elements, lighting fixtures, etc.

The electroluminophores or luminescent pigments are embedded in a transparent, organic or ceramic binder. The starting materials are mostly zinc sulfides, which generate different, relatively narrow-band emission spectra depending on the doping or co-doping and the preparation process. The focus of the spectrum determines the respective color of the emitted light.

In connection with the present application, transparent is understood as the opposite of opaque, ie as recognizable translucent or noticeably transparent in the general sense of speech. In this sense, transparency does not require almost 100% light transmission. A light transmission of 15% is also still considered to be transparent. On the other hand, only a slight light permeability, ie a degree of transmission that only allows light sources to shimmer weakly, is no longer understood to be transparent. The exciting AC voltage field generally has a frequency of a few hundred Hertz, the effective value of the operating voltage often being in a range from approximately 50 to 150 volts. By increasing the voltage, a higher luminance can generally be achieved, which is usually in a range from approximately 50 to approximately 200 candelas per square meter. Increasing the frequency usually causes a color shift towards lower wavelengths. However, both parameters must be coordinated to achieve a desired lighting impression.

The alternating field is applied over thin surface electrodes which are arranged on both sides of the luminescent layer and are at least transparent on the visible side. The electrode layers, together with the luminescent layer and possibly additional dielectric layers and / or color-filtering or color-converting layers, form a flat luminous capacitor.

For practical and design reasons, the luminescent layers of EL displays are usually designed as a larger number of non-contiguous partial areas, which each serve as display segments and / or picture elements. The individual display segments and / or picture elements can be designed in different colors and in a wide variety of shapes and are generally referred to below as "partial picture areas". Most of the time, at least one of the electrode layers is only implemented in the area of the partial image areas, in particular, however, when partial image areas are to be individually controllable, for example for running image-like effects, flashing effects, changing display texts, etc.

Conventional EL displays, in particular EL displays used as advertising signs or display boards, generally have a structure comprising two glass or plastic panes with a conductive coating, the luminous capacitors being arranged between the panes and being contacted at the rear, for example via carbon conductive rubbers.

Large-area displays in particular are relatively expensive to manufacture, since two largely rigid panes have to be used in production. The weight of the finished displays is also considerable due to the two panes. Against this background, it is an object of the present invention to provide an EL display which can also be implemented as a single-pane structure without losing its function and appearance compared to conventional EL displays. Furthermore, the EL display should be easy to manufacture and reliable in operation. Last but not least, a high-quality appearance is sought, ie elements that do not contribute to the actual information display or decorative effect, such as, for example, conductor tracks and the like, should be able to be implemented as inconspicuously as possible.

This object is achieved by an electroluminescent display according to claim 1. Advantageous embodiments can be designed according to one of claims 2-1 3.

The rear contact layer, which preferably consists of transparent conductive lacquer, permits contacting of the jerk electrode layer, which preferably contains silver or carbon, in the area of the image area without visible conductor tracks. The contact layer preferably touches the jerk electrode layer directly in the region of the recess or recesses of the insulation layer, i.e. without intermediate layer. Is the image area divided into several non-contiguous partial image areas, e.g. Subdivided display segments, letters, etc., the contact layer can be divided into contact areas separated from one another by narrow interruptions in order to enable separate electrical control and thus independent illumination of the partial image areas. The transparent conductive lacquer can be, for example, (doped) polythiophene, which is available, for example, under the trade name Orgacon (registered trademark of the Agfa-Gevaert group). Transparency is understood as defined above. However, transparent layers according to the present invention preferably allow light transmission of at least 25%, particularly preferably over 40%, ideally over 60%.

The carrier is preferably a glass or plastic glass pane, which can be made transparent or partially transparent. Partially transparent is understood to mean both regionally transparent carriers and non-transparent yet nevertheless noticeably translucent carriers (for example made of frosted glass or sandblasted glass). A wide range of mineral and organic glasses is suitable, in addition to ordinary or hardened window glass, for example acrylic glass (PMMA) or polycarbonate glass. The carrier is preferably the only supporting layer consisting predominantly of glass or plastic glass in the structure of the EL display; In this context, multilayer safety glass is considered as one layer. In this context, layers can in particular also be conceived as a load-bearing layer which have a certain minimum bending stiffness, for example a bending stiffness according to DIN -53 1 21 of more than 100 mNm (longitudinal). In this context, a luminescent layer with acrylate binder (artificial glass-like formation of the matrix in which the luninophores are embedded) is not to be regarded as a load-bearing plastic casting layer. Rather, the absence of a second supporting gas or synthetic glass layer means that the construction contrary to the prior art does not obengeschilderten au ^~ f two but only on a conductively coated disc is built. In this way, considerable weight savings can be achieved compared to known EL displays, and the thickness of the overall structure is also reduced. For the same purpose, the insulation layer is preferably thinner than a millimeter. Furthermore, the insulation layer is preferably made of plastic.

The electrode layer resting on the carrier or, if appropriate, an intermediate layer is preferably also made of transparent conductive lacquer. However, another transparent, conductive coating of the carrier is also conceivable, for example sputtering with indium tin oxide (Indium ^" Tin Oxide, ITO). Suitable glasses coated with tin oxide are commercially available at relatively low prices

The voltage supply of the contact layer and the electrode layer can take place via so-called bus bars. These are bordering or (partially) bordering, highly conductive structures made of silver and / or copper and / or carbon pastes or the like.

The back of the EL display is preferably insulated with a back insulation layer, which can advantageously consist of a thin plastic film, a non-conductive lacquer or the like. If both this and the insulation layer arranged on the side of the contact layer facing the carrier are made transparent, then there is an EL display which is transparent outside the image area and in which, due to the transparency of the contact layer, no electrical line elements interfere with the visual impression (possibly provided Bus bars can be found on Edge of the EL display can be provided and therefore covered by means of a frame or a clamping device or a narrow, visible-side, bordering, opaque cover). Possibly. Suitable recesses for contacting the bus bars must be provided in the provided insulation or back insulation layer.

In principle, each variant of the invention described or indicated in the context of the present application can be particularly advantageous, depending on the economic and technical conditions in the individual case. Unless stated otherwise, or as far as technically feasible, individual features of the described embodiments can be exchanged or combined with one another.

Examples of preferred embodiments of the present invention are explained in more detail with reference to the accompanying drawings. The drawings are not to scale and are to be understood purely schematically.

1 shows a perspective view of a section through part of an EL display according to the invention. For reasons of clarity, the layer thicknesses have been greatly increased and, in the manner of an exploded drawing, gaps between adjacent layers are shown.

2a-2e show different layers of an EL display according to the invention, constructed similarly to FIG. 1, in the rear view, i.e. Cuts parallel to the image plane of the EL display. The figures can also be understood as representations of various stages in the manufacture of the EL display

Fig. 1 and Fig. 2a-e show a largely identical layer structure, so that the same reference numerals are used for corresponding components. The figures can be viewed in parallel, the layer structure in FIG. 1 being explained from bottom to top and thus in the production sequence of the individual layers. The visible side, that is to say the side facing the intended viewer, is shown at the bottom in FIG. 1 and the rear side at the top. The electrode layer 2 made of transparent conductive varnish is applied to a carrier 1 made of mineral or plastic glass (FIG. 2a). The luminous layer 3 is arranged thereon within the contours which are intended to form the image surface, which is a transparent matrix 5 in which the electroluminophores 4 are embedded. The layer 3 can be designed as a cast or extruded film, but also as a screen printing layer or the like. In particular, the representation of the electroluminophores 4 is to be understood purely schematically. In practice, efforts are made to obtain particles that approximate the spherical shape.

Electroluminophores are usually sensitive to the effects of moisture. Therefore, additional layers can be integrated, which take over the function of a moisture barrier or vapor barrier. However, these can largely be dispensed with, in particular, if microencapsulated electroluminophores 4 are used. The microencapsulation is usually oxidic or nitridic, however, for example, an organic microencapsulation or a diamond-like carbon encapsulation ("diamond-like carbon") is also conceivable.

The luminescent layer 3 can be divided into a plurality of discrete subareas 3a, 3b, as shown in FIG. 2b, which each represent individual picture elements, display segments, symbols, characters (in the present case in the form of the letters L and T). A thin additional dielectric layer 6 can advantageously be provided on the back of the luminescent layer 3. The silver-containing jerk electrode layer 7, which in principle can also be designed differently, extends within the contours of the luminous layer 3 or its discrete partial areas 3a, 3b over an area which is approximately as large as the area of the luminous layer 3 or its discrete partial areas 3a, 3b, however, leaves a narrow edge area 8 of the latter or the dielectric layer 6 free in order to largely rule out a risk of breakdown (in cooperation with the electrode layer 2).

The next layer in the structure is a transparent insulation layer 9, preferably made of a plastic material, which has cutouts 10 in the area of the jerk electrode layer 7 and in a narrow edge area 11 of the electrode layer 2, in order to enable them to be contacted from the rear for the voltage feed , The contacting of the jerk electrode layer 7 through the cutouts 10 of the insulation layer 9 takes place via the contact layer 1 2 made of transparent conductive lacquer, which is carried out almost over the full area, but does not quite reach the narrow edge area 11 for contacting the electrode layer 2 in order to exclude short circuits. The contact is advantageously made directly, ie without additional layers between contact layer 1 2 and jerk electrode layer 7. The voltage is fed into contact layer 1 2 and electrode layer 2 via bus bars 1 3a, 13b, which can be printed, for example, from conductive silver paste and, in the present case, from aesthetic ones Aspects are not all-round. In the case of very large-area EL displays, however, bus bars that run almost completely around can be advantageous in order to achieve a uniform luminance and to avoid local heating.

The back of the EL display is insulated with the transparent back insulation layer 14, which preferably consists of a plastic material.

Of course, the EL displays according to the invention can also have additional, non-luminous image components or image elements backlit by means of the luminous layer 3, for example in the form of prints, glass etching etc.

Claims

1 . Electroluminescent display, comprising an at least partially transparent support (1), - a transparent electrode layer (2) arranged on the support (1), a luminous layer (3) containing electroluminophores (4), which represents an image area, a jerk electrode layer (7) in the area A large part of the image area, an insulation layer (9) which has a recess (10) in the area of the jerk electrode layer (7), a transparent contact layer (1 2) arranged at least partially on the insulation layer (9) for contacting the jerk electrode layer (7).

2. Electroluminescent display according to claim 1, wherein the electrode layer (2) is made of transparent conductive lacquer.

3. Electroluminescent display according to one of the preceding claims, wherein the contact layer (12) is made of transparent conductive lacquer

4. Electroluminescent display according to one of the preceding claims, wherein the insulation layer (9) is at least partially transparent.

5. Electroluminescent display according to one of the preceding claims, comprising a back insulation layer (14) for insulating the side of the contact layer (12) facing away from the carrier (1).

6. The electroluminescent display according to claim 5, wherein the back insulation layer (14) is at least partially transparent.

7. Electroluminescent display according to one of the preceding claims, wherein the carrier (1) consists predominantly of glass or plastic glass.

8. The electroluminescent display according to claim 7, wherein the carrier (1) is the only supporting layer of the electroluminescent display consisting predominantly of glass or plastic glass.

9. Electroluminescent display according to one of the preceding claims, wherein the electrode layer (2) and / or the contact layer (1 2) is in each case contacted by means of a bus bar (13a, 1 3b).

1 0. Electroluminescent display according to claim 10, wherein the bus bar (1 3a, 1 3b) is designed with the inclusion of a conductive paste.

1 1. Electroluminescent display according to one of the preceding claims, wherein the image area is divided into a plurality of non-contiguous partial image areas.

1 2. Electroluminescent display according to ^" Claim 1 1, wherein the partial image areas can be controlled individually and / or in groups.

1 3. Electroluminescent display according to one of the preceding claims, wherein the contact layer (1 2) touches the jerk electrode layer (7) in the region of the recess (10) directly.