Abstract:
An apparatus for illumination having a housing suited for in ground use, which contains at least one lamp which is surrounded by a reflector, a controller for controlling the lamp and light changing means. To reduce the content of moisture, air containing evaporated water is able to be released from the lamp to the surroundings and only air without moisture is allowed to enter the in-ground lamp.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an apparatus for illumination comprising at least one housing suited for in ground use, which housing might contain at least one lamp, which lamp can be surrounded by reflective means, which housing further can comprise light changing means, which housing also can comprise control means for controlling at least the lamp and the light changing means. 
   The present invention also relates to a method for preventing moisture build-up inside an apparatus for illumination, which apparatus contains at least one lamp, which lamp is surrounded by reflective means which apparatus is communicating with control means for controlling at least the lamp. 
   2. Description of Related Art 
   U.S. Pat. No. 6,210,014 describes a material and a system for reducing condensation in enclosed vehicle lamp housings, and more particularly a condensation vent comprising a water vapor material within, on or integrated with the housing to reduce the condensation and prevent or minimize entry of liquid water and/or other foreign matter. 
   U.S. Pat. No. 6,210,014 describes a lamp used in a car where an opening in the upper par of the lamp is covered by a diaphragm for venting the lamp. Inside the car, the car itself protects the venting opening so that no mechanical damage occurs to the diaphragm. Using an upwards pointing diaphragm for in ground use will be completely impossible because in ground devices are subjected to the outdoor environment. In ground installations could often be placed where people are walking or even where cars are driving. This means, that a diaphragm would be subjected to pressure, which would destroy the diaphragm immediately. At least, a kind of mechanical protection is necessary. The diaphragm must be protected from being overflowed because the diaphragm is tight for water from the outside, in the overflowed situation, it will also be tight for water from the inside. In this way, the technology described in U.S. Pat. No. 6,210,014 could not be used for an in ground installation. 
   U.S. Pat. No. 6,540,374 describes an in ground lighting fixture having multiple separate and watertight compartments for the various components of the fixture, allowing for maintenance and service of the fixture without exposing weather-sensitive components to the elements. The fixture also includes a pan and tilt assembly, which can be selectively controlled with a common household tool to change the direction of the light without having to access the pan and tilt assembly. 
   U.S. Pat. No. 6,540,374 describes a water tight compartment for in ground use, but the document does not describe any effective ventilation means, which may lead to the fact that water inside the in ground lighting fixture will condensate on the inner side of the outside surfaces including the top window which is visible from the outside. During operation, the temperature inside the lighting fixture will increase, and the water inside will evaporate. An increasing pressure will probably press part of the moisture out through openings, but as soon as the lamp is shut off, the temperature drops which leads to a pressure reduction inside the in ground lighting fixture, and probably at least over time, air with a high moisture content is sucked back to the inside of the in ground lighting fixture. The reduced pressure inside the lamp housing could lead to a flow of water through the connecting cables. The cables might be placed deeper in the ground than the lamp and the cables might be surrounded by water. A reduced pressure in one end of a cable starts a pumping effect, which can lead to an inflow of water into the lamb housing. 
   SUMMARY OF THE INVENTION 
   The scope of the invention is to reduce the content of moisture in an in ground lamp by allowing air with a content of evaporated water to be released from the lamp to the surroundings and only allow air without moisture to enter the in ground lamp. 
   This can be achieved by a housing comprising an outer casing which casing might comprise at least one diaphragm covering at least one opening in the casing which diaphragm might be permeable for moisture for transmission from the inside of the housing to the outside, and that is water tight from the outside. 
   Hereby, it is achieved that the volume inside the housing is vented through the diaphragm. Each time the lamp is turned on the inside temperature, the pressure in the housing increases. If there is moisture content in the housing, the increasing temperature will cause the moisture to evaporate, and air containing moisture penetrates the diaphragm. After a shut down, the temperature and pressure inside the housing decrease. Air with a low content of moisture penetrates the diaphragm and the pressure inside the housing is mostly equal to the atmosphere pressure. This way, suction of water through small openings in the casing or through cables is avoided. By keeping the housing dry moisture build-up in the top window is avoided. Also the different components in the housing have a longer lifetime in the dry atmosphere. 
   The opening in the casing might be placed in the lower part of the casing and directed downwards. Hereby, protection of the diaphragm from the harsh environment above the apparatus is achieved. The diaphragm is also protected from being covered by ice and/or snow, and if the apparatus as such is overflowed, there will probably be an air pocket at least partly below the apparatus around the diaphragm. This apparatus can operate normally in nearly all environments. Even in a situation where the apparatus is completely overflowed, the diaphragm is as such protected from water penetrating from the outside. As soon as the apparatus is in operation, increasing pressure will force air from the inside through the diaphragm out in the surrounding water where bubbles are formed. Depending on the shape of the apparatus, the bubble can be maintained just under the apparatus until the apparatus is turned off where air with a very low moisture content is allowed to penetrate the diaphragm, and the bubble on the outside is reduced. 
   The opening in the casing might, as an alternative, be placed in the lower part of the casing in a vertical direction. Hereby, it is achieved that drops of water on the outside of the diaphragm is pulled downwards by gravity to keep the diaphragm open. 
   The apparatus might comprise at least changeable means for forming the light beam. Hereby, it is achieved that different light forming devices can be used, and they could be changeably based on an inside generated commanding signal or on an outside commanding signals. Hereby, different light effects can be achieved during illumination; even moving means could be used and as such form the movement in the light that is projected onto a target. 
   The apparatus might also comprise means for colour change of the light beam. Hereby, it is achieved that the colour of the light can be changed. One possible apparatus can contain a colour wheel with different colours stored in that colour wheel, and by rotating the colour wheel based on an internal generated commanding signal or an external generated commanding signal, different colours could be achieved in the projected light. In a modified apparatus the change of colour of the light can take place by electric control of a lamp. Instead of using colour wheels, linear movement of colour filters in and out of the light beam can be used for achieving sliding changes of colours. The technique of colours changes together with means for forming the light beam, can give a lot of different effects which can be achieved as the two techniques can be used in combination. 
   The apparatus might comprise controllable means for pan and tilt of the light beam. Hereby, it is achieved that the direction of the light can be changed into different directions. In an in ground lighting fixture, there is a limited angle for pan or tilt in all directions because the movement of the lamp unit has to take place inside a housing. Changing of pan or tilt could be made mechanically such that the lamp is adjusted once, but in another possible apparatus, the pan and tilt of the lamp could be done by servo motors controlled from the apparatus or from the outside by a commanding signal. In this way, the direction of the light could be movable during operation. 
   The apparatus can be divided into a first section and a second section, which first section contains the lamp chamber, and the second section contains electric power components and a control circuits for control of the lamp and/or servo motors, which second section contains power and data connections. Hereby, it is achieved that the temperature from the lamp has a limited influence on the temperature of the electronic components. 
   The first section of the housing might comprise a lamp chamber having a bottom wall, below which bottom wall the second section of the housing can be placed in which a number of separate chambers are formed, where a first chamber can contain electronic power components, where a second smaller chamber can contain control circuits for controlling servo motors for adjustment of shape and/or colour and/or pan and/or tilt, where a third chamber can contain power connections, and where a fourth chamber can contain data connections. Hereby, it is achieved that different components are placed in different chambers where negative influence from some parts of the components to other parts of the components in this way is reduced. Placing the lamp in a separate chamber allows this chamber to be heated up to a certain extent without high temperatures having any direct influence on the electronic components, which are placed in separate chambers below. By placing the different electronic components in different chambers, the same effect occurs, in that for example, the power components are all placed in one chamber in which chamber, the temperature can increase to a higher level than in the second chamber where all control circuits are placed. The heating that occurs in the first and the second chamber can widely be transmitted to the surroundings through walls of the housing to the surrounding environment. It is possible to let a small opening from the first and second chamber to be opened towards the lamp chamber placed above it. In this way, moisture from the two chambers can enter the lamp chamber where most of the moisture due to the higher temperature probably is contained as moisture in the air and as such be led out through the diaphragm to the environment. 
   The lamb chamber and the first and the second chambers are open to the flow of air, and the lamb chamber is tight towards the third and fourth chambers. Hereby, it is achieved that the third and the fourth chambers are mostly isolated from the rest of the apparatus. This means that moisture, which enters these two chambers, is restricted from getting further into the apparatus. As the third and the fourth chambers are the only chambers, which have cable connections to the surroundings, they are the only chambers where moisture can enter the apparatus. Furthermore, because these two chambers only contain cable connections, the moisture content in these two chambers is mostly uncritical. 
   The first and second chambers are separated by a cut through, which is open downward to the surroundings, which cut through is open towards the bottom wall of the lamp chamber, where the bottom wall in an area above the cut through contain an opening covered by a diaphragm. Hereby, it is achieved that the opening points downwards without being placed in the lowest part of the apparatus. In this way, it is achieved that under normal conditions, there will always be air around the cut through, and there will be air towards the diaphragm. In this way, it is achieved that the diaphragm will function correctly for a long time period, and even if the apparatus is partly overflowed, the cut through which is placed between the first and the second chamber will probably be kept dry. The cut through between the first and the second chamber also increases the size of the surface of the housing that surrounds the two chambers. Therefore an increase in the total surface able to perform a heat transfer to the surroundings is achieved. 
   The diaphragm is placed in a diaphragm holder, which diaphragm holder is replaceable in an opening in the bottom wall. Hereby, it is achieved that during maintenance of the apparatus, the diaphragm is replaceable. Even if the diaphragm is rather stable, it can during a long period be filled up with dirt on both the inside and the outside surface, and as the diaphragm as such is a rather cheap component, an exchange only takes very few seconds. Therefore, if there is a normal maintenance of the apparatus where, for example, the lamp is changed, the diaphragm might be changed as well. 
   In an alternative embodiment of the invention, the first and second sections can be separated, where the second section might be placed beside the first section for achieving access to the second section, where cables can connect the first and the second section. Hereby, it is achieved that there can be easy service access to both houses. Service to the electronic part can be carried out without opening the lamp housing. By placing the second section side by side, the first section reduces the high of the apparatus. Then the apparatus could be used indoors where both sections could be placed under a floor. 
   The invention also relates to a method comprising the use of permeable means for moisture transmission from the inside of the apparatus to the outside and for transmission of dry air from the outside to the inside. 
   Hereby, moisture build-up inside an apparatus that operate under outdoor conditions is prevented. 
   In the following, the invention will be described with reference to the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a cut through of a first embodiment of the invention, 
       FIG. 2  shows a three-dimensional cut through of a preferred embodiment of the invention, 
       FIG. 3  shows an enlarged cut through seen from a different angle of the bottom of the invention, 
       FIG. 4  shows a perspective view of a diaphragm holder, 
       FIG. 5  shows a cut through of the diaphragm holder, and 
       FIG. 6  shows an alternative embodiment of the invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows an apparatus  2  according to a first embodiment of the invention where the apparatus  2  has a housing  4 , which comprises an outer casing  6 , a top glass  8  surrounding a lamp chamber  10  where the outer casing  4  further comprises a bottom casing  12 . Between the lamp chamber  10  and the bottom casing  12  a bottom wall  14  is placed dividing the housing  4  into an upper part and a lower part. The lamp chamber  10  comprises a lamp unit  20 , which contains a lamp socket  22 , a reflector  24 , optical means  26  and changeable means  28  for forming the shape of the light. Furthermore the light passes through means  30  for colour change of the light where the lamp unit  20  is held in position by means  32  for pan or tilt of the lamp unit  20 . The lamp unit  20  further comprises optical means  34  and a glass cover  36 . The bottom casing  12  shows different separated chambers: a first chamber  50 , a second chamber  52  and a third chamber  54 . The chamber  50  contains electric power components, i.e. power transistors for ballast capacitors and coils. The second chamber  52  contains electronic control units for controlling motors for a change of light form or a colour change of the light, or for a change of pan or tilt. The chamber  54  contains cable connections for the apparatus  2 . 
     FIG. 2  shows an apparatus  102  comprising a housing  104 , which housing  104  contains an upper casing  106 , a top glass  108  defining a lamp chamber  110  and a bottom chamber  112 . Between the lamp chamber  110  and the bottom chamber  112 , a bottom wall  114  is formed. This bottom wall  114  contains an opening  116  which opening  116  is covered by a not shown diaphragm. Inside the lamp casing  110 , a blowing unit  118  is also seen. The casing  110  further comprises a lamp unit  120  comprising a lamp socket  122  and a reflector  124 . The tamp unit  120  further comprises optical means  126 , and means  132  is shown for pan and tilt of the lamp unit  120 . This unit further comprises means for forming the shape of light and also means for colour change. These means are not shown on this figure. Below the lamp chamber  110 , the bottom casing  112  is shown. This bottom casing  112  shows a first chamber  150 , a second chamber  152  and a third chamber  154 . Between the chambers  150  and  152 , the cut through  160  is shown. Further between the chamber  150  and the chamber  154 , a cut through  162  is shown. 
     FIG. 3  shows parts of the same embodiment as shown in  FIG. 2 , but the cut through is seen from a different direction.  FIG. 3  shows part of an apparatus  202  having a housing  204  with a casing  206  and lamp chamber  210 . A bottom casing  212  ends the bottom of the casing. Between the lamp housing  210  and the bottom casing  212 , a bottom wall  214  is formed. This bottom wall  214  contains a diaphragm holder  216  placed in a hole  217  which hole penetrates the bottom wall  214  and continues through an upper wall in the bottom casing  212 . The diaphragm holder  216  penetrates the holes and ends in the cut through  216 . The holding means  216  comprises a diaphragm  262  to allow moisture from the inside of the casing  210  to penetrate the diaphragm  262  and escape through the cut through  260 . In the opposite direction from the cut through  260  and into the casing  210 , only dry air can penetrate the diaphragm  262 . 
     FIG. 4  shows a diaphragm holder  316 , which contains an upper part  364  cooperating with the opening  217  shown at the  FIG. 3 . Directly below the upper part  364  of the diaphragm holder  316 , a partly circular upwards directed recess  368  is shown which might contain an O-ring for tightening against the upper part of the bottom casing  212 . The holding means  316  further comprises a cylindrical section  366 , which penetrates through the opening in the upper part of the casing  212 . At the bottom of the cylindrical part  366 , tightening means  370  is seen tightening against the movable part  372  which can be screwed out for replacement of the diaphragm  362 . Venting openings  378  are open towards the diaphragm  362 . 
     FIG. 5  shows a cut through of the diaphragm holder  316 , which is also shown in  FIG. 4 . The diaphragm holder in  FIG. 5  shows an upper part  364 , which upper part continues into a cylindrical section  366 . The cylindrical surface  366  might be treated so the diaphragm holder could be screwed into a housing. Below the upper part  364 , a shoulder and a recess  368  are shown, where the recess  368  is suited for an O-ring that can tighten if the cylindrical part  366  is screwed into a housing. The upper part  364  is connected to a lower part  372 , which is screwed into an opening  374  in the upper part. Between the lower part  372  and the upper part  364 , an O-ring  370  is seen. The lower part  372  also comprises ventilation openings  378 . 
     FIG. 6  shows an alternative embodiment  402  showing a first section of a housing  406 , which comprises an upper glass  408  and a lamp housing  410 . Besides this, the second section of the housing  412  is shown having an upper closure  482  which is removable from the outside where cables  486  are connecting the first section of the housing  406  and the second section of the housing  412 . 
   Placing the two housing sections side by side leads to a reduced total height of the apparatus, and furthermore it also allows service access for the second section of the housing  412  by opening the closure  482  for service and maintenance in the second section  412 . Especially, if the apparatus  402  is used indoors placed under a floor, the reduced height of the apparatus is necessary because there is a maximum allowable distance where you can hide the lamp housing under a floor without penetrating the ceiling totally.