EP1261983B1 - Silent discharge lamp with a controllable colour - Google Patents

Abstract

A silent discharge lamp which comprises a discharge vessel filled with a gas fill, a plurality of electrodes divided into separately operable groups, a dielectric layer between at least one anode part of the electrodes and the gas fill, and a luminescent layer which has elementary luminescent surfaces of at least two respective luminescent colors. Each elementary luminescent surface is assigned to a different electrode group. The electrode groups and the elementary luminescent surfaces are in each case two-dimensionally interleaved relative to one another so that the light emission surface of the gas discharge lamp can essentially be lit using each electrode group on its own, and the gas discharge lamp is designed so that it is possible to control the color of the light emission by controlling simultaneous operation of the electrode groups.

Description

Technical area

The present invention relates to a so-called silent gas discharge lamp. This refers to gas discharge lamps, which are designed for so-called dielectrically impeded discharges. For this purpose, at least the anode (s) is or are separated by a dielectric layer of the gas filling serving as a discharge medium. In bipolar operated gas discharge lamps, all electrodes are dielectrically impeded.

State of the art

Silent discharge lamps as such are known. They are of interest for various applications, in particular for the backlighting of displays in flat screens and the like. For this application, the design is known as a so-called flat radiator, in which the lamp consists essentially of two plane-parallel plates, which can be connected via a frame and enclose the discharge medium between them. One of the two plates serves as a light emitting surface of the flat radiator.

Preferably, these silent gas discharge lamps are operated with a pulsed operating method with which a particularly high efficiency of the generation of light (UV light or preferably visible light at Use of phosphors) can be achieved. Also, the details of this operating method are known in the art and the expert, so that will not be discussed in detail here.

It is also known to use a divided into a plurality of groups electrode assembly in a silent gas discharge lamp, wherein the groups can be operated separately from each other. This makes it possible, for example, to illuminate different areas of an instrument assembly independently of each other and to turn on and off this lighting for the different areas, with a total of only one lamp use. Here, the different areas of the instrument lighting can also be colored differently, so find phosphors or phosphor mixtures of different colors use. Reference is made to EP-A-0 926 705

Presentation of the invention

This invention is based on the technical problem of expanding the field of application and possible uses for silent gas discharge lamps.

For this purpose, on the one hand there is provided a gas discharge lamp with a discharge vessel filled with a gas filling having a plurality of electrodes divided into separately operable groups, a dielectric layer between at least one anode part of the electrodes and the gas filling and a phosphor layer, the phosphor layer having at least two phosphor partial areas assigned to the electrode groups having respective phosphor colors, characterized in that the electrode groups and the phosphor sub-surfaces are each interleaved flat surface so that the light-emitting surface of the gas discharge lamp can be illuminated with substantially each electrode group for themselves, and the gas discharge lamp is designed so that by controlling a simultaneous operation of the electrode groups, a control of the color of the light emission is possible.

In addition, the invention is also directed to an operating method for such a gas discharge lamp, in which the electrode groups are operated simultaneously with each controlled power and in this way the relative ratios of the emitted light colors of the phosphors are controlled.

Preferred embodiments are given in the respective dependent claims.

Finally, the invention is also directed to an image display device with a plurality of such gas discharge lamps, which will be discussed in more detail later in the description.

The basic idea of the invention is that the total color of the light emission of the discharge lamp should be controllable, namely as a mixed color of at least two colors of phosphors or phosphor mixtures. For this purpose, as known per se, the electrodes are divided into groups which are operable in a shared manner. Each of the electrode groups is associated with a phosphor surface which forms a partial area of the entire light emitting surface of the gas discharge lamp. This phosphor part surface is provided with a respective phosphor or phosphor mixture and generates a certain color during operation of the lamp. The operation of an electrode group thus means light emission with the associated phosphor (mixture) color. However, the total radiation should act as a mixed color, so the individual phosphor sub-areas in the application of the eye of the beholder at an adjusted observation distance or diffusion through diffuser elements of the discharge lamp or reflection on illuminated objects or the like as possible no longer be resolved, including the electrode groups and the assigned Fluorescent faces are spatially interleaved with each other. How fine the structure of this local nesting should be is a matter of special application. In any case, the phosphor sub-areas should not form self-contained separate compact blocks within the entire light emission area of the gas discharge lamp, but rather be interlocked or otherwise interleaved with each other in relation to this total light emission area. In other words, the entire light-emitting surface should be able to be illuminated by each electrode group for itself substantially.

With these inventive measures, one or the other of the at least two phosphor colors can now be produced during operation of the lamp and, by simultaneous operation, a mixed color thereof. Meanwhile, since it has been found that silent discharge lamps of this type can be dimmed, which also applies to individual electrode groups, the simultaneous operation of the electrode groups with the different phosphor colors not only produces a certain mixed color, but also continuously changes it.

With regard to suitable dimming methods and the measures useful for this purpose, reference is made to two earlier patent applications of the same Applicant, the contents of which relating to the power control in the individual electrode groups and also to preferred features of the electrode structure within these electrode groups. On the one hand, this is the German patent application 198 44 720.5 (corresponding PCT / DE 99/02885), on the other hand the German patent application 198 45 228.4 (corresponding PCT / DE 99/03109). To avoid unnecessary length of the present application, repetitions of the contents of these referenced applications will be waived. It is thus assumed that with suitable electrode structures, in particular those with a discharge gap which varies in a monotonic manner within so-called control lengths, by varying parameters of the electrical power supply, in particular the voltage amplitude in the pulsed operating method, or the dead time between the pulses, the power of the lamp can be continuously controlled in relatively large areas. In particular, by introducing particularly small discharge spacings in a part of the electrode pairs and by an associated operating method with particularly long dead times, operation can also take place at a very low power level. In the present context, this is to be understood as meaning that different discharge spacings can also be present within an electrode group corresponding to a phosphor ink, ie subgroups can be formed in connection with the dimming method.

In principle, only two primary colors are required for the invention according to the above embodiments, with which a spectrum of mixed colors can be spanned up to the pure primary colors. Of course, a larger scope for design is available with a larger number of primary colors, with three primary colors having three groups of electrodes (in the following being group groups being understood as grouping with regard to color control) being sufficient. The details of the assignment of certain phosphors to different primary colors and the details of the color mixing in fluorescent lamps is not discussed here, because it is also a matter of basic knowledge of the skilled person and the prior art. In particular, phosphors suitable for VUV excitation from prior applications are also known for silent discharge lamps.

For the sake of clarity, it should be added that the phosphor subareas need not be clearly delineated, but may merge into one another. In the current production methods, however, a defined boundary between the phosphor partial surfaces will usually be found. In addition, the groups z. B. in connection with the dimming properties be divided into subgroups, as stated above. Incidentally, the associated phosphor subareas do not have to be coherent in each case, but may also consist of a multiplicity of individual, respectively interrelated fields on the light emission surface.

One possible application of the invention is to produce white light adjustable color temperature. In conventional gas discharge lamps, white light is generated by common excitation of a so-called three-band mixture of different phosphors. In this case, the phosphors or phosphor mixtures corresponding to the three primary colors (three bands) are thus mixed together.

In such conventional gas discharge lamps, the color temperature of the white tone can be adjusted only by the proportions of the dyes in the total dye mixture. It must be made for each color temperature desired its own dye mixture and thus its own gas discharge lamp and purchased by the user and stored. In contrast, a silent gas discharge lamp can be produced with the procedure according to the invention, in which the color temperature can be adjusted in addition to the overall brightness by the fine adjustment of the respective power of the individual electrode groups. In principle, this argument, of course, applies to other sounds in addition to white light, but the commercial importance of white light of different color temperature is greatest.

In addition to the adjustment on the part of the user but also other advantages can be achieved: For example, standardized lamps can be equipped with different ballasts, so as to produce different color temperatures depending on the application. It could be waived adjustability on the part of the user, for example because anyway, only a smaller number of different standard color temperatures is of interest. Also, a ballast with switching possibility between different, predetermined color temperatures can be provided.

On the other hand, it may also be interesting to be able to produce a larger color spectrum or a color spectrum that is as complete as possible with a gas discharge lamp according to the invention. This applies in particular to a preferred application of the lamps according to the invention as picture elements of a larger picture display device. In this case, this image display device consists of a large number of planar side by side arranged gas discharge lamps, which thus each form full color pixels. The image information can be generated by controlling the brightness of the individual pixels, ie lamps, whereby the overall image display device can operate as a color display in accordance with the colors that can be represented by the individual pixels. As compared with a conventional color picture tube, the single lamp corresponds to a set of adjacent primary color pixels (usually three). However, it is also possible to use in the image display device gas discharge lamps according to the invention only for the generation of the necessary colors and represent the actual figurative image information thereof, such as an upstream LCD display or other brightness filter.

For details of such an image display device is otherwise referred to the embodiments and a co-pending application of the same applicant of the same filing with the title "image display device from a variety of silent gas discharge lamps" (DE 100 63 931.3), the disclosure of which is hereby incorporated by reference.

Description of the drawings

• Fig. 1 zeigt schematisch den Aufbau einer Lichtabstrahlungsfläche einer stillen Gasentladungslampe mit zwei, jeweils Primärfarben entsprechenden Leuchtstoffteilflächen;
• Fig. 2 illustriert schematisch eine geeignete Elektrodenstruktur dazu;
• Fig. 3 illustriert den Aufbau einer Variante zu Fig. 1, nämlich die Verschachtelung von drei, jeweils Primärfarben entsprechenden Leuchtstoffteilflächen;
• Fig. 4 illustriert schematisch eine aus stillen Gasentladungslampen gemäß den Fig.1 - 3 aufzubauende erfindungsgemäße Bildanzeigeeinrichtung.

In the following the invention will be explained in more detail by means of exemplary embodiments, which are illustrated in the figures. In the above and in the following description, the disclosed features are to be understood both with regard to the device category and with regard to the process category.

• Fig. 1 shows schematically the structure of a light emitting surface of a silent gas discharge lamp with two, each primary colors corresponding phosphor partial surfaces;
• Fig. 2 schematically illustrates a suitable electrode structure therefor;
• Fig. 3 illustrates the structure of a variant of Figure 1, namely the interleaving of three, each primary colors corresponding phosphor partial surfaces.
• FIG. 4 schematically illustrates a picture display device according to the invention to be constructed from silent gas discharge lamps according to FIGS.

Fig. 1 shows schematically the surface structure of a light emitting surface 1 of a silent gas discharge lamp. The light emission surface 1 corresponds essentially to the translucent ceiling plate of a conventional silent flat radiator, with the exception of the details explained below. It can be seen that the light emission surface 1 is divided into a checkerboard pattern in two phosphor sub-areas 2 and 3. The phosphor sub-areas 2 and 3 are understood as the sum of the respective light and dark squares, each phosphor sub-surface 2 and 3 thus forms half of the light-emitting surface and is alone Excitation already able to illuminate the light emitting surface 1 substantially completely. Due to the relatively fine checkerboard pattern-like interleaving between the phosphor sub-areas 2 and 3 is at a certain observation distance with the eye no longer dissolve, which is the Fluorescent faces 2 or 3 is excited to emit light. Of course, this does not apply to the different colors which are given by the phosphors or phosphor mixtures of the phosphor partial surfaces 2 and 3. In this example, the phosphor part surface 2 is to emit a blue hue and the phosphor part surface a yellow hue. Thus, in addition to the shades yellow and blue, shades are also to be represented in a continuous green spectrum, which results from the mixture of the two primary colors.

The homogeneity can be further enhanced by additionally switching a diffuser element known per se for homogenizing the luminance distribution in the case of screen backlights in front of the discharge lamp, for example a prism sheet or a ground glass screen.

FIG. 2 shows an example of an electrode structure suitable for FIG. 1. The two middle horizontal lines 4 correspond to two anodes, the approximately to these anodes 4 rectangular meandering electrode strips 5 and 6 are separately operable cathodes with respective projections 7 for the localization of single discharge structures 8. The cathode 5 is executed by dashed lines to them from the cathode Of course, it is, of course, a continuous train.

Due to the separate operability of the cathodes 5 and 6, there are two electrode groups 4, 5 and 4, 6 (with common anodes), to which the respective discharge structures, schematically indicated as triangles, are assigned. In the figure, it is therefore assumed that both electrode groups operate simultaneously.

It goes without saying that the electrode strips 4, 5, 6 must be insulated from one another at the points of intersection and in the areas in which they run relatively close together. For this purpose, in particular in the adjacent areas, a corresponding safety distance between the Cathode strips 5 and 6 may be provided, which is not shown in Fig. 2 drawing.

It goes without saying that the squares respectively enclosed between the cathodes 5 and 6 and the anodes 4, in which the individual discharge structures 8 lie, are arranged in the lamp directly below the individual squares of the phosphor partial surfaces 2 and 3. As a result, the electrode groups 4, 5 and 4, 6 are each assigned to one of the two phosphor partial surfaces 2 and 3. Depending on the extent of the individual squares and depending on the distance between the discharge structures 8 and the phosphor partial surfaces (in the sense of the figures perpendicular to the drawing plane), one of the two electrode groups 4, 5 and 4, 6 naturally also gives rise to a certain excitation of their not actually assigned other phosphor partial surface. This slightly impairs the purity of the primary colors when only one of the two electrode groups 4, 5 and 4, 6 is operated, but does not fundamentally change the basic principle of representing all mixed colors between the representable primary colors.

Fig. 3 shows a variant of the pattern of Fig. 1, which is designed for three primary colors. The phosphor sub-surfaces are denoted by 9, 10 and 11 and in this variant correspond to the primary colors blue at 9, green at 10 and red at 11. Thus, a correspondingly constructed gas discharge lamp is in principle able to display a full color spectrum. The remarks on FIG. 1 apply otherwise. The electrode structure necessary for the variant in FIG. 3 is of course somewhat more complex than that shown in FIG. 2 and will not be explained in detail here because nothing fundamentally new results from this.

Fig. 4 shows schematically a large-sized image display device 12 with a frame 13, which erects a large rectangular flat screen wall 14 and carried raised above the ground. Such an image display device 12 could for example be used as an information surface in a large sports stadium or be mounted as a billboard, for example on house walls, then of course without the frame 13 drawn here.

The flat screen 14 consists essentially of a large number of planar side by side mounted individual gas discharge lamps 15, which are constructed according to FIGS. 1 and 2 or according to FIG. 3. As a result, they form full-color pixels for a color representation with two or three primary colors. The graphic image information (ie light / dark information) has a size corresponding to the size of the individual gas discharge lamps 15 spatial resolution. The flat screen 14 should thus be designed so that the viewer can recognize an image at a total viewing distance and preferably no longer perceives a single lamp for himself.

Incidentally, the remark already mentioned in the introduction to the introduction also applies that, by dividing the individual lamps, a higher spatial resolution of the graphic representation and of the color representation can be achieved than corresponding to the individual lamp size. This is essentially an economic question, namely, whether a set of smaller lamps, or a larger, but subdivided, larger format lamp, is cheaper to manufacture.

An essential advantage of the use of silent discharge lamps for image display devices 12 as in FIG. 4 is that a very high luminance can be achieved with the silent discharge lamps with a reasonable power consumption. In addition, silent discharge lamps are extremely switch resistant, ie well suited for time-varying continuous applications. They also show virtually no tarnish or temperature dependence of the luminous power. These advantages are for applications such image display devices in sports stadiums, in concert broadcasts, in advertising, in traffic control systems and in all other applications in which it depends on the large-format image display, particularly suitable.

Claims (8)

1. Gas discharge lamp (15) having a discharge vessel filled with a gas fill, and having a plurality of electrodes (4, 5, 6) divided into separately operable groups (4,5; 4,6), a dielectric layer between at least one anode part (4) of the electrodes and the gas fill, and a luminescent layer (2, 3, 9, 10, 11),
   wherein the luminescent layer (2, 3, 9, 10, 11) has elementary luminescent surfaces (2, 3, 9, 10, 11) of at least two respective luminescent colors assigned to the electrode groups (4,5; 4,6), characterized in that
   the electrode groups (4,5; 4,6) and the elementary luminescent surfaces (2, 3, 9, 10, 11) are in each case two-dimensionally interleaved relative to one another so that the light emission surface (1) of the gas discharge lamp (15) can essentially be lit using each electrode group (4,5; 4,6) on its own,
   and the gas discharge lamp (15) is designed so that it is possible to control the color of the light emission by controlling simultaneous operation of the electrode groups (4,5; 4,6).
2. Gas discharge lamp (15) according to claim 1, in which three electrode groups and, assigned thereto, three elementary luminescent surfaces (9, 10, 11) are each provided with one luminescent primary color.
3. Gas discharge lamp according to one of the preceding claims, which is designed to produce white light with an adjustable color temperature.
4. Gas discharge lamp (15) according to one of the preceding claims as a flat panel lamp.
5. Image display device (12) having a plurality of gas discharge lamps (15) according to one of claims 1, 2, 4 arranged next to one another in a plane to form a surface, in which each gas discharge lamp (15) corresponds to a full color pixel.
6. Method of operating a gas discharge lamp (15) according to one of claims 1 - 4, in which the electrode groups (4,5; 4,6) are operated simultaneously with a respectively controlled power, and the relative proportions of the light colors emitted by the luminescent materials (2, 3, 9, 10, 11) are controlled in this way.
7. Method of illumination using an operating method according to claim 6, in which the color temperature of white light illumination is adjusted by controlling the relative proportions of the emitted light colors.
8. Method of displaying an image using an image display device (12) according to claim 5, in which a color picture is formed from a plurality of color pixels by controlling the color emission of the individual gas discharge lamps (15).

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