EP0976144A1

EP0976144A1 - Flat signalling lamp with dielectrically impeded discharge

Info

Publication number: EP0976144A1
Application number: EP98965815A
Authority: EP
Inventors: Frank Vollkommer; Lothar Hitzschke
Original assignee: Patent Treuhand Gesellschaft fuer Elektrische Gluehlampen mbH
Current assignee: Osram GmbH
Priority date: 1997-12-23
Filing date: 1998-12-11
Publication date: 2000-02-02
Also published as: WO1999034410A1; HUP0001317A3; JP2001513256A; US6348760B1; HUP0001317A2; EP0926704A1

Abstract

The invention relates to a flat signalling lamp with dielectrically impeded discharge, intended for use especially in traffic signalling elements, notably traffic lights.

Description

Flat signal lamp with dielectric barrier discharge

Cross references

Reference is made to the following parallel application by the same applicant with the filing date of December 23, 1997: European patent application No. 97122800.2 with the title “signal lamp and phosphors therefor”.

Technical field

The present invention relates to the field of signal lamps, as they are used above all for traffic signals and traffic signs. In particular, it relates to a traffic light.

In addition to the diverse lighting tasks, the area of signal lamps is also part of lamp technology. The term signal lamp is primarily to be understood as a lamp which informs the viewer of an event or a state (informs). This information is usually conveyed to the viewer by the lamp being on or off. In addition, the lamp can convey additional information content to the viewer, for example through its shape, color or lettering.

Daily life knows many areas of application for signal lamps. B. road traffic, shipping and rail traffic, the monitoring and operation of technical facilities of all kinds, security signs for buildings or traffic, commercial or industrial facilities such as airports, train stations, cinemas and the like.

Particular requirements for the area of signal lamps are characteristic. This includes reliability, operating time, and repair and maintenance work. This is not only due to safety considerations, but also follows from the large number and local distribution of signal lamps and the associated considerable expenses for maintenance and repair.

Another important aspect is that certain types or sizes of signal lamps are desired depending on the application.

State of the art

Conventional incandescent or halogen incandescent lamps are conventionally used, especially for signal lamps which have to be switched on and off during operation.

The disadvantages resulting from this are first of all the high sensitivity to vibrations of the filament. This results in considerable restrictions, particularly in applications in the transport sector. Furthermore, depending on the type of lamp and the operating voltage used, incandescent lamps only have a relatively limited operating time of a few thousand hours and then, as mentioned above, sometimes have to be replaced with considerable effort. Ultimately, a short regular operating time is just as disadvantageous as any other susceptibility to defects.

Another aspect often arises from special requirements for the

Radiation pattern. Then the light bulbs must be in an optical

System are installed, e.g. B. with a specular reflector and / or with lenses. First of all, incorrect adjustments and corresponding restrictions come. In addition, such optical systems have a complicated structure and are fundamentally susceptible to contamination, such as cannot be avoided, especially in the traffic sector. As a result, time-consuming internal cleaning is necessary for regular maintenance work, but it is still not possible to completely restore the initial properties of the system.

With mirror reflectors, it can also be used in so-called phantom lights when the sun is low. B. come in traffic lights. A reflection of the signal lamp in question is simulated by reflections of the sunlight.

Another disadvantage of the optical systems with reflectors or lenses that are often required in incandescent lamp applications are the necessary size and design and the corresponding weight. In many cases, they are very undesirable, especially if the lamp has to be installed in special positions and therefore considerable effort is involved in the assembly and / or in the corresponding holders, masts or other fastening devices. However, the necessary lighting of a larger signaling area or a z. B. emission standard given by standards no other choice.

A final aspect is the temperature development of incandescent lamps, which on the one hand is large in terms of overall output and on the other hand is strongly localized. The resulting thermal cycles and thermal gradients put a strain on the lamp and its technical environment, particularly in the case of non-stationary operating states. The result is a relatively limited switching strength.

A known way to remedy some of the disadvantages mentioned is to use light-emitting diodes (LEDs); they are however often unsuitable because of their radiation characteristics. A further disadvantage is that the color location, which is important and often standardized in many signal lamp applications, cannot be set or cannot be set permanently when using phosphors because of stability problems.

Presentation of the invention

This invention is based on the technical problem of specifying a new signal lamp which offers possibilities for avoiding the difficulties mentioned.

According to the invention, this problem is solved by a gas discharge lamp with a discharge vessel which is at least partially transparent to visible radiation and filled with a gas filling and with a dielectric layer between at least one discharge electrode and the gas filling for a dielectrically impeded discharge in the discharge vessel, characterized in that the lamp has a Signal lamp with a signal area and the discharge vessel has a continuous boundary surface which corresponds to the signal area.

The invention is based on the knowledge that many conventional reservations about the use of gas discharge lamps in the field of signal lamp technology can either be overcome technically or the associated disadvantages can be accepted in favor of other advantages. First of all, there is an argument against the use of gas discharge lamps compared to incandescent lamps or halogen incandescent lamps because of the need to use complex starting circuits or electronic ballasts. On the other hand, significant progress has been made in reducing the price and size, particularly in the area of electronic ballasts, and also in the area of conventional Halogen incandescent lamps are accepted by transformers in low-voltage technology similar disadvantages.

Another point is the reduced switching resistance of gas discharge lamps due to the starting process. It has been found here that switching discharge strengths can be achieved by gas discharge lamps with dielectrically impeded discharge, which far exceed the conventional incandescent lamps and are essentially determined only by the stability of the phosphors or phosphor mixtures used. Because of the shape of the electrode, which is insensitive to incandescent filaments, and the smaller thermal cycles during operation, the switching stability can now be seen as an advantage of gas discharge lamps with dielectric barrier discharge compared to conventional incandescent lamps. Here too, a prejudice stemming from conventional gas discharge lamp technology has not proven to be justified in this special case.

Another point that initially speaks against the use of discharge lamps is related to the continuous use of mercury in the corresponding gas fillings. Mercury not only has adverse environmental aspects, it also causes adverse temperature properties of the lamp. First of all, this concerns the instant light properties, i.e. the (lack of) possibility of emitting the full light output immediately after switching on. In addition, this problem also depends on the outside temperatures, i.e. particularly pronounced in a cold environment. It has now been found, however, that when a lamp with a dielectric barrier discharge is used, gas fillings containing mercury are no longer necessary, which completely eliminates these problems.

A major advantage of this invention is the geometry, which can be adapted very flexibly to the individual requirements in terms of shape and size. special of flat lamp discharge lamps. Discharge lamps are characterized by a largely homogeneous distribution of the light generation over the discharge volume, so that additional optical components can often be omitted. So the z. B. in traffic lights, the disturbing phantom light-producing specular reflectors and the additional diaphragms used to reduce the phantom light are not necessary. Rather, the flat radiator discharge lamp alone can achieve a much better result with regard to the phantom light effect than when these components are used in the conventional case, which makes an important contribution to traffic safety.

The mirror reflectors have led to the possibility of being able to set and select the directional distribution of the light radiation very well. In this respect, there were concerns that in the case of gas discharge lamps, in particular if additional specular reflectors are dispensed with, an undirected radiation, for example, B. to get into the half-space, which does not generate sufficient luminance in the really decisive directions. As explained further below, however, possibilities have been found according to the invention for concentrating the luminance distribution even in the case of surface-emitting gas discharge lamps if this is necessary in a specific application.

By dispensing with mirror reflectors, diaphragms and other separate optical components, the requirements for the external shape of the signal lamp or light, which resulted primarily from the prior art, are also eliminated. B. with regard to a certain minimum thickness, the at least preferred use of a round outer shape, etc. The same applies to the weight saving.

Accordingly, the problems described above with the internal contamination of signal lamps, for. B. traffic lights. There By choosing the appropriate fluorescent material or mixture, a large number of color words can be made, the conventionally required filter disks are often saved. Not only does it gain in light output, the interior cleaning area is completely eliminated. With a correspondingly dense or encapsulated version of the signal lamp according to the invention, the occasionally necessary external cleaning can be carried out particularly easily, for. B. with a water jet that can also be used from a greater distance.

In connection with the saving of the conventionally required reflectors, filter disks etc., there is also the advantage of the invention that the costly adjustment of the position of the light bulb or its base, which is necessary due to the adjustment due to the thermal cycles during operation or at least when changing the light bulb, is also eliminated .

Fluorescent lamps are also generally less sensitive to vibrations than incandescent lamps and are therefore much more suitable for use with signal lamps subject to various mechanical shocks or vibrations, especially in the traffic sector.

This invention is primarily intended for flat radiator discharge vessels in which a continuous flat shape of the discharge volume directly at least essentially specifies the shape of the flat radiator. In contrast, e.g. B. conventional tube discharge vessels, which, for example, backlight a flat lens, no continuous flat discharge vessels if they are coiled or filled in serpentines to fill the area to be backlit. Of course, the flat radiator can nevertheless have wavy surfaces or be curved in its flatness. The signal area mentioned in claim 1 is the area used to exercise the signal function of the signal lamp. It can have a signal color, have lettering, carry danger symbols etc. This signal area does not have to be identical to the assigned boundary area of the discharge vessel and can be separated from it, for example, by different optical intermediate layers. In any case, the signal area is backlit or illuminated at least in substantial parts through the boundary area and corresponds to it at least in this sense. The signal area and the corresponding boundary area are preferably geometrically congruent.

In a preferred embodiment of the invention, the electrodes of the flat radiator discharge vessel are arranged on one of its surfaces, in particular in such a way that they run side by side. This common arrangement on a surface of the discharge vessel results in the possibility of particularly simple manufacture, because only one surface has to be coated with electrode structures. In addition, discharge structures that fill the surface can be produced particularly uniformly. This becomes clear from the description of the exemplary embodiment which follows below.

In this preferred form of the discharge electrodes, the discharge anodes and the discharge cathodes from a plurality of parallel discharge anodes and cathodes can each be connected together on a common side (the anodes or the cathodes) and connected to a single anode or cathode connection. In particular, as shown in the exemplary embodiment, a straight-line shape of the discharge anodes and cathodes with common connections running on opposite sides to a comb-like arrangement of the discharge anodes and cathodes should be considered. In favor of improved control and thus greater uniformity of the arrangement of the individual discharges or discharge structure in the discharge volume, projections can be provided on the electrodes for local fixing of an individual discharge element, that is to say an individual one of the plurality of discharges. Here too, reference is made to the exemplary embodiment.

In the case of the dielectric barrier discharge, at least the anode side must be covered with a dielectric layer. The dielectric layer also listed in the main claim can, however, also be formed by a wall of the discharge vessel if at least some of the electrodes are applied to the outside of this wall.

In many cases, especially if the light is to be emitted only on one side, the use of a reflective layer on a discharge vessel wall is provided, in contrast to the diffuse reflection of the light from the lamp in contrast to the specular reflector. Gas discharge lamps usually contain phosphor layers on the walls of the discharge vessel, in which case the reflection layer should lie on the side of the phosphor layer facing away from the discharge. However, the use of a phosphor is not mandatory for this invention. If it is possible to discharge freshly disabled persons, in which the desired light is generated directly in the discharge, this invention can also be carried out without a phosphor.

The radiation behavior of the gas discharge flat radiators is fundamentally relatively diffuse, ie directed in all directions of exit from the plane of the flat radiator. This also applies to the optional use of a diffuse reflection layer. For some applications, a further embodiment of the invention is preferred, in which the solid angle range which essentially covers the half-space (in the case of a reflection layer on one side) Light radiation is restricted to a narrower solid angle range. According to the invention, luminance amplification layers, in particular Fresnel lenses or prism foils or prism plates, are used as simple flat optical elements on the flat radiator. In particular, so-called brightness enhancement films can be used as prism films, which narrow the cone of the light emission into one dimension, or if two brightness amplification films crossed at right angles in their longitudinal direction of the prism are used in two dimensions. Such brightness enhancement films are described in more detail below in the exemplary embodiment. The luminance amplification layers can also be constructed without a prism, for example with a refractive index variation.

Furthermore, a diffusely scattering film or plate can be used, with the use of a prism film at the lamp side thereof. Such a diffuser is particularly advantageous when a larger area of the discharge vessel is stabilized by support points, that is to say small columns running transversely to the plane of the flat radiator between the plates enclosing the discharge volume. These support points are less visible due to the diffuser.

The Xe excimer system can be considered as the preferred discharge system for the discharge lamp described here largely with regard to its geometric and electrotechnical structure. This is preferably used with a pulsed discharge operation. Regarding the details of Xe-Excimer discharge lamps and the pulsed discharge operation, reference is made to the applications WO 94/23442 or DE-P 43 11 197.1 and WO 97/04625 or DE 195 26 211.5, the disclosure of which is referred to here and is included. This invention relates generally to signal lamps of all kinds. Various fields of application have already been described in the introduction. However, it is particularly useful in the transport sector, namely in road traffic, rail traffic, shipping traffic and air traffic. A particular aspect of the invention accordingly relates to a traffic sign or a traffic signal which contains a signal lamp according to the invention or consists of it. Many of the advantages of the invention mentioned, such as the lower susceptibility to soiling, the phantom light problem, the longer operating time, particularly in the case of locations subject to vibration, the improved switching stability, etc. play a particularly large role in the area of traffic signs and traffic signals.

In this context, a traffic light is to be considered in particular, the two or three differently colored signal lamps of which are each a flat fluorescent lamp according to the invention. The exemplary embodiment also relates to this. It is also important to use it as a motor vehicle lamp, e.g. B. brake light, or direction indicator, which can also be built around a vehicle corner and can be designed curved. In all of these cases, as is generally the case with signal lamps, it is particularly advantageous to be able to adjust the frequently standardized color, more precisely the color location, through the correct choice of phosphor or phosphor mixture. Not only are there particularly good technical options for the exact setting of the color location, but there is often no need for conventional color filter technology.

Description of the drawings

The following is a description of the preferred exemplary embodiment, namely a signal lamp for a traffic light. This embodiment is shown in the figures, which shows: FIG. 1 shows a sectional top view of the signal lamp for a traffic light,

FIG. 2 shows a sectional side view through the signal lamp,

FIG. 3 shows a plan view of a base plate of the signal lamp, the electrode structure being shown,

FIG. 4 shows a schematic illustration of three signal lamps according to FIGS. 1 to 3 assembled to form a traffic light.

In Figure 1, a round signal lamp 1 is drawn for a traffic light. The sectional view shows the discharge volume within the smallest circle 2. Sections through support points 3 arranged in a square grid of 34 mm edge length are shown as small round dots. The area between the smallest circle 2 and the middle circle 4 represents the lateral sealing of the discharge volume from the outside world. The outer circle 5 is the outer edge of glass plates 6 which delimit the discharge volume upwards and downwards (in the view of the figure) and 7. These glass panes are shown in section in Figure 2. In this embodiment, the diameter of the three circles 2, 4 and 5 are 200, 220 and 240 mm.

FIG. 2 shows a section in a direction perpendicular to FIG. 1. A Xe discharge filling is enclosed between the two glass plates 6 and 7. Typical thicknesses for the glass plates are 2.5 mm and for the gas filling 8 about 5 mm. Ag electrodes 9 are first drawn in cross section on the lower glass plate 7, the geometry of which is described in more detail with reference to FIG. 3. A glass solder layer 10, which forms the dielectric of the dielectric barrier discharge, is located on the electrodes 9. There follows a reflector layer 11 made of A1 ₂ 0 ₃ or Ti0 ₂ for diffuse reflection of the light generated in the lamp 1. A phosphor layer 12 for generating light is located above the reflector layer 11. The same phosphor layer 12 is also located on the lower side of the upper glass plate 6 in the illustration. These phosphor layers are optimized for the respective application, in particular the desired color location. For the present example of a traffic light, preferred luminescent materials or luminescent material combinations can be found in the European application of the same applicant, herewith disclosed in terms of its disclosure, from the same day with the title: "Signal lamp and luminescent materials therefor" and the file number 97122800.2.

In some applications, e.g. B. with the red signal lamp of the traffic lights, it may be useful to provide a color filter 13 on the glass plate 6, compare the application just cited.

Above the glass plate 6 and the optical color filter 13 is a diffuser 14 which diffuses the light generated by the phosphor layers 12 and reflected by the reflector layer 11 to such an extent that the reference points in FIG. 1 can only be seen in the luminous appearance of the signal lamp are weakly recognizable.

The electrodes and layers 9-12 applied to the glass plates 6 and 7 can be produced particularly simply by the screen printing process. The screen printing process is u. a. advantageous for structuring the electrodes. For the sake of simplicity, it is also used for the other layers.

On the optional color filter 13 and the diffuser 14 there are in turn two luminance intensifying foils 15 and 16 crossed with their longitudinal prism axes. Such luminance intensifying foils are prism foils which, through refraction of the light on the prism surfaces, cause the radiation cone of the light to narrow in the plane perpendicular to the prism longitudinal axis. An example of this are the "Brightness Enhancement" films commercially available from the manufacturer 3M. Depending on the application, the angle of attack of the prisms can be optimized in order to align the emitted light to the required extent.

In this exemplary embodiment, the signal surface is the luminous surface on the upper luminance reinforcing film 16. The signal function is reduced to the illumination of the red, yellow or green signal lamp 1. On the other hand, the boundary surface of the discharge vessel corresponding to the signal surface is the upper glass plate 6 Apart from the interposition of the different optical layers, these areas correspond and are congruent.

FIG. 3 shows a top view comparable to FIG. 1, but only the geometry of the electrodes 9 that cannot be seen in FIG. 1 is shown on the lower glass plate 7. You can see a toothed basic geometry that resembles two straight, interdigitated combs. In this comb-like geometry, the anodes 9a shown on the left in the figure are each in pairs, while the cathodes 9k shown on the right are each individually between adjacent anode pairs. The cathodes 9k have small projections 17 arranged alternately on both sides along their length, which each serve for the spatial fixing of an individual discharge structure. For this electrode structure, reference is made to the application DE 196 36 965.7, the disclosure of which is included here. The next distance between two distances is 5 mm in this exemplary embodiment or 10 mm between projections on the same side.

The area of the limitation of the anode and cathode combs 9a and 9k corresponds to the inner circle 2 already mentioned in FIG. 1. The electrodes are in each case on the left and the right side in the figure a common anode or cathode connection brought together, which lies on the outer circumference of the outer circle 5 introduced as the outer edge of the glass plates in FIG. These respective circular segments, which represent circular segments over the longitudinal extent of the inner circle 2, are led out to an anode connection or to a cathode connection in FIG. 3 below.

Finally, FIG. 4 shows in a schematic view how three of the signal lamps 1 described so far are combined to form a traffic light. Because of the special design of the individual signal lamps 1, a very flat housing 18 can be used which, moreover, has the usual high rectangular shape. The elements used in conventional traffic lights with incandescent lamps, such as lenses, screens and parabolic mirrors, can be omitted here. Nevertheless, the advantages of the invention which have already been described are achieved, in particular the phantom light effect no longer occurs because there is no specular reflector which could reflect the obliquely incident sunlight. Such a traffic light 19 could be attached to a very simple and easily constructed stand, but can also be easily hung on ropes due to the low weight and, on the whole, offers multiple possible uses due to the significant simplifications in weight and volume and the great freedom for the housing 18.

In the case of motor vehicle signal lamps, the freedom in the choice of shape is very important with regard to the body design. In the simplest case, the signal lamp shown in FIGS. 1-3 can also be thought of as a circular red taillight or a circular yellow direction indicator of a car. The lamp can also be curved around a corner of the vehicle. This can be of particular advantage in the case of rear lights, brake lights or direction indicator lamps, which then also come from the side of the vehicle can be recognized by other road users. Since the invention enables the construction of particularly flat motor vehicle lamps, such a routing around a motor vehicle corner is possible without the considerable structural depth, which is conventionally predetermined thereby, into the body.

Claims

claims

1. Gas discharge lamp (1) with a discharge vessel which is at least partially transparent to visible radiation and filled with a gas filling (8) and with a dielectric layer (10) between at least one discharge electrode (9) and the gas filling for a freshly-impeded discharge in the Discharge vessel,

characterized in that the lamp (1) is a signal lamp with a signal surface and the discharge vessel has a continuous boundary surface (6) which corresponds to the signal surface.

2. Signal lamp (1) according to claim 1, in which the discharge electrodes (9) are arranged on a surface (7) of the discharge vessel opposite the signal surface.

3. Signal lamp (1) according to claim 1 or 2, in which a plurality of parallel discharge anodes (9a) or cathodes (9k) are each connected to a common side of the anodes (9a) or cathodes (9k) and on a single anode or a single

Cathode connection are connected.

4. Signal lamp (1) according to one of the preceding claims, wherein at least one of the discharge electrodes (9) has a structure of projections (17) for local fixing of the individual discharge elements of the dielectric barrier discharge.

5. Signal lamp (1) according to one of the preceding claims, in which at least part of the electrodes (9) of the discharge vessel is applied to the outside of a wall and the dielectric layer is formed by the wall.

6. Signal lamp (1) according to one of the preceding claims with a reflection layer (11) on a wall of the discharge vessel for diffuse reflection of the light from the signal lamp (1).

7. Signal lamp (1) according to one of the preceding claims with a diffuser (14) arranged on the boundary surface (6) of the discharge vessel corresponding to the signal surface.

8. signal lamp (1) according to claim 7 with a corresponding to the signal area boundary surface (6) of the discharge vessel and on the diffuser (14) arranged luminance enhancement layer, such as a prism sheet (15, 16), prism plate or Fresnel lens.

9. signal lamp (1) according to claim 8 with two in their prism longitudinal direction crossed at right angles brightness enhancement films (15, 16) as prism films.

10. Signal lamp (1) according to one of the preceding claims, designed for a Xe excimer discharge.

11. Signal lamp (1) according to one of the preceding claims operated by a pulsed energy coupling.

12. Traffic sign or signal with a signal lamp (1) according to one of the preceding claims.

13. Traffic signal according to claim 12 as a traffic light (19).

14. Traffic signal according to claim 12 as a motor vehicle lamp.

15. Motor vehicle lamp according to claim 14 as around a vehicle corner, curved rear, brake light or direction indicator lamp.