Patent Document

CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     The present application claims priority from European Patent Application No. 06007445.7, filed Apr. 7, 2006, the contents of which is herein incorporated by reference in its entirety.  
       BACKGROUND OF THE INVENTION  
       [0002]     The invention relates to a method for introducing an accurately dosable amount of mercury into the discharge vessel of a lamp, in particular into a straight fluorescent lamp. The discharge vessel is connected to a lamp receptacle and is charged with a gas stream via the lamp receptacle and is filled, moreover, with a predetermined amount of mercury via a mercury-introducing channel. Furthermore, the invention relates to a suitable device.  
         [0003]     Fluorescent lamps are manufactured on fully automated production machines, where the lamp blanks run through a plurality of processes in the horizontal position. These processes include: baking out the fluorescent substances, which are suspended in the discharge vessel, melting an electrode into the ends of the discharge vessel, evacuating the discharge vessel, filling the discharge vessel with an inert fill gas, introducing a predetermined amount of mercury and then sealing air-tight the discharge vessel on both ends of the discharge tube.  
         [0004]     The documents U.S. Pat. No. 2,699,279, U.S. Pat. No. 2,842,290 and U.S. Pat. No. 2,726,799 describe how liquid mercury is dosed from a container as a part of a fully automated production machine for evacuating and filling straight discharge vessels with inert fill gas and mercury.  
         [0005]     Such fully automated production machines are wide spread and have been used for many years.  
         [0006]     An alternative method for introducing mercury into the discharge vessel of fluorescent lamps is disclosed in WO 97/19461. In the method described in that patent, a metal strip, which is coated with a mercury compound is mounted on the electrodes. After the discharge vessel has been sealed air-tight, in particular melt-sealed, the metal strip and the mercury compound on said metal strip are heated inductively; and the mercury is released.  
         [0007]     The heating of the mercury strip in the finished lamp has the result that eventually other undesired components, in particular H 2 , are released from the metal strip; and these components have an extremely negative impact on the igniting and burning properties of the lamp.  
         [0008]     In order to absorb at least to some extent these disturbing materials, a getter material is usually also applied on the metal strip. This getter material must also be heated inductively in order to activate itself. The heating that is necessary to activate the getter or rather to release the mercury is achieved by introducing inductive energy. In order to heat the metal strip up to a range between 900° and 1,000° over a period ranging from 10 to 30 seconds, a very strong alternating electromagnetic field must be applied. A certain radiation of the antenna in the factory, which could have a negative impact, for example, on persons with cardiac pacemakers, cannot be avoided. The energy costs for a lamp throughput of 7,000/h is noticeable; and the energy efficiency of this method is extremely low. The production of the metal strip with the mercury and getter compounds that are applied by pressure on said metal strip (usually in the shape of a welded ring) and the manipulation during the lamp production makes the getter strip technology very time-consuming and expensive.  
         [0009]     In the aforementioned Hg-liquid dosing method the scattering of the dosed amount is very large. Depending on the type of lamp, the fluorescent material and other specific construction features, there is a consumption of the introduced mercury during the service life, which ought to be in a magnitude of 20,000 hours. Therefore, one usually overdoses in order to make sure that one has the minimum amount of mercury that is necessary for operating the lamp and to guarantee the envisaged average life of the lamp.  
         [0010]     In contrast, the object of the present invention is to provide a method for introducing an accurately dosable amount of mercury into the discharge vessel of lamps. This method is to ensure that the dosing can be carried out with significantly higher accuracy than with the prior art methods. Furthermore, a corresponding device shall be provided.  
         [0011]     According to a core idea of the invention, this problem is solved in that in a preparation step during or after dosing the amount of mercury to be introduced, the mercury is brought in a dosed volume in the form of a single, coalescing drop or adherent drop. Then in a fill step the entire amount of mercury to be introduced is transported—while still maintaining the previously formed drop—into the discharge vessel. To this end there is a change-over mechanism, which in the preparation step guides the gas stream past the drop via a bypass channel and in a fill step blocks the bypass channel in such a manner that, while the bypass channel is blocked, the gas stream is guided over the dosed volume and drags the drop along with it into the discharge vessel.  
         [0012]     Consequently one core consideration consists of bringing the entire gas stream for the process of introducing behind the already pre-dosed drop of mercury in order to let the drop be conveyed by the gas stream into the discharge vessel.  
         [0013]     Even though the dosing of the drop could already be carried out spatially separately or temporally far in advance, it is preferred that the dosing be carried out by means of or rather within the dosed volume. However, it is ensured that exactly the pre-dosed amount of mercury is available for filling into the discharge vessel.  
         [0014]     According to another preferred aspect of the present invention, the drop is formed as a structure having at least an approximately spherical shape. Correspondingly in another preferred design, the device is provided with a dosing borehole, which is dimensioned in such a manner that in said borehole the drop can form into a single bead, whose predetermined diameter is defined by the circumference of the dosing borehole.  
         [0015]     Therefore, the dosing borehole is configured differently than in the state of the art so that the drop has room only as a bead, a feature that is also claimed as an independent idea of the present invention. In the state of the art, on the other hand, the dosing borehole is designed oblong or long stretched-out so that the mercury divides into a plurality of small beads. However, this division is not repeatable; the beads are small and are poorly conveyed.  
         [0016]     In the preferred design of the invention, however, the inventive dosing of the mercury so as to form a single bead as well as the process control or process technological adaption with respect to rerouting or bypassing the gas stream interact.  
         [0017]     In order to further improve the introduction of the drop of mercury, it is advantageous to avoid bypasses at angles greater than or equal to 90°. For example, the drop may be guided over two bypasses of, for example, 45° each. As an alternative, it is also conceivable to guide the drop in a channel, which exhibits in particular a continuous bend, especially by providing a curved acceleration channel in such a manner that sharp angles are totally avoided. Especially if a curved acceleration channel is provided, it may also be provided that this channel empties without a bend and/or without any steps into the feed channel. The above described aspects are also claimed as independent inventions irrespective of the formation of exactly one drop or the rerouting of the gas stream.  
         [0018]     In another preferred design the drop of mercury is guided in such a manner that at transitions steps or rather edges in the direction of introduction are avoided. Corresponding transitions may be designed so as to be either totally flat, or the drop may be guided in such a way that the diameter of the guiding mechanisms is expanded at the transitions so that the drop of mercury does not impinge upon any impediment in the direction of travel.  
         [0019]     According to a special aspect of the present invention, the dosed volume may be designed as a dosing borehole and may exhibit a length that is equivalent to approximately the diameter of a circle, inscribed in the cross section of the dosing borehole.  
         [0020]     According to another aspect of the present invention, the length of the dosing borehole may also be somewhat shorter than the diameter of a circle, inscribed in the cross section of the dosing borehole, in order to ensure that in cutting off the mercury stream above the dosing borehole just one drop actually forms despite the high surface tension of the mercury in the dosing borehole.  
       SUMMARY OF THE INVENTION  
       [0021]     The object of the present invention is also solved from a device-related viewpoint by a device for introducing an accurately dosable amount of mercury into the discharge vessel of lamps, in particular straight fluorescent lamps, comprising at least one lamp receptacle, to which the discharge vessel is attached. Furthermore, the device is characterized in that the lamp receptacle exhibits a feed channel, which communicates with the interior of the discharge vessel and that there is a dosing unit, which pre-doses a predetermined amount of mercury in a dosed volume and delivers the amount of mercury that was pre-dosed in the dosed volume to the feed channel for the purpose of introducing into the discharge vessel. The dosed volume is dimensioned in such a manner that the mercury therein forms into a single drop. The dosing unit exhibits a change-over mechanism in order to block and/or reroute, if necessary, a gas stream, flowing through a bypass channel past the dosed volume.  
         [0022]     Here, too, the core consideration consists of rerouting, if desired, the gas stream in the introduction phase of the drop of mercury in such a way that the drop is dragged along with the gas stream into the discharge vessel.  
         [0023]     It is especially preferred if the dosed volume is designed as the dosing borehole and is dimensioned in such a manner that a drop of at least approximately spherical shape is formed.  
         [0024]     According to another aspect of the present invention, the dosing borehole of the inventive device is constructed with walls that are shaped or rather aligned with respect to each other in such a way that the drop, which is formed at least approximately in the shape of a bead, makes only point-by-point or section-by-section contact with the walls of the dosing borehole. Thus, the formation of a bead or rather of a spherical shape of approximately compact structure is promoted; and at the same time friction forces arising during the subsequent release from the dosing borehole are reduced.  
         [0025]     In a preferred design the dosing borehole may be formed specifically as a recess, whose cross section exhibits a shape that is essentially in the form of an isosceles triangle. Thereby, the legs of the isosceles triangle in a first design may be arranged to run in a straight line. In an alternative design they may be designed to run in a manner that is convex or concave with respect to the interior of the dosing borehole.  
         [0026]     According to another preferred aspect of the present invention, an acceleration channel is provided between the dosing unit and the feed channel. Said acceleration channel is oriented in such a manner that the drop is transferred into the feed channel subject to the action of gravitational force with an additional gravitation-induced momentum. In the state of the art, the mercury, which is divided into a plurality of individual beads and accelerated by gravitational force, also impinges on the feed channel. However, in the state of the art this happens at right angles so that no portion of the momentum remains effective in the longitudinal direction of the feed channel. According to the invention, on the other hand, an additional gravitation-induced momentum is exploited for transporting the mercury inside the feed channel in the direction of the discharge vessel. This aspect is claimed as an invention irrespective of the formation of the mercury in the shape of a single drop or the rerouting of the gas stream.  
         [0027]     The acceleration channel and the feed channel may be arranged relative to each other in such a manner that the acceleration channel empties into the feed channel at an angle of &lt;90°, preferably &lt;60°, furthermore preferably &lt;50°. Thus, an undisturbed transport of the mercury from the acceleration channel into the feed channel is guaranteed.  
         [0028]     According to another preferred aspect of the present invention, the bypass channel empties into the feed channel and exhibits one or more inflow orifices, which face away from the discharge vessel, for the purpose of charging the discharge vessel with a gas stream, in particular with an inert fill gas.  
         [0029]     According to a special aspect of the present invention, the at least one, preferably two or more inflow orifices can be closed with covers. To this end, the inflow orifices are arranged off-axially in relation to the feed channel.  
         [0030]     According to a special aspect of the present invention, the inflow orifice(s) and the cover(s) may be opened or closed by rotating the inflow orifices in relation to the covers or by rotating the covers in relation to the inflow orifices.  
         [0031]     According to another aspect of the present invention, the dosing unit comprises a tilt spoon unit, which is beared or mounted coaxially to the feed channel and may be tilted between a dosing position and a release position. The tilting action through rotation of the lamp receptacle occurs because owing to its geometric shape and/or owing to an additional trim weight the center of mass of the tilt spoon unit is clearly outside its rotational axis about the feed channel. In this design a separate drive for the tilt spoon unit is not necessary. Rather the dosing position and the release position alternate solely on the grounds of a tilting motion, triggered by the force of gravity, as the lamp receptacles rotate. These lamp receptacles may be spaced, as well-known from the U.S. Pat. No. 2,699,279 or U.S. Pat. No. 2,726,799, equidistant apart from each other in a predetermined number on a circular disk that rotates during the production process.  
         [0032]     In another preferred design, the tilt spoon unit comprises a scoop arm with a spoon, mounted on its end. According to a special aspect of the present invention, which ensures an especially fast tilting and thus a highly repeatable dosing or release, the center of mass of the tilt spoon unit is set apart from the rotational axis by a distance that is equivalent to approximately 5% to 25% of the total radial extension of the scoop arm, including the spoon, from the rotational point up to its radially outermost point.  
         [0033]     According to another aspect of the present invention, which is also claimed independently, the side of the spoon that faces away from the scoop arm exhibits a roof that tapers off radially outwards, in particular to form a ridge or a peak and that encourages the mercury to run off or drain off the radial exterior or the radial external side of the spoon. This ensures that the mercury, which is located on the radially external side of the spoon, cannot flow along the tilt spoon unit in the direction of the inflow orifice and/or a gas passage borehole (to be explained below), which aligns with the dosing borehole in the release position.  
         [0034]     Preferably the feed channel exhibits an upstream first section and a downstream second section, both being oriented coaxially to the other and at the same time beared or mounted in a way that they can rotate about their common axis in opposite directions.  
         [0035]     According to a special aspect of the present invention, which is also claimed independently of the dosing and the transport of the drop, which is, if possible in the shape of a bead, and/or the rerouting of the gas stream, a cone surface of the first section engages with an orifice of the second section that faces said first section. The result is that the first section and the second section lie comparatively close to each other, while at the same time the ability to rotate the two sections in opposing directions is preserved.  
         [0036]     In order to further improve the sliding seal, the orifice of the second section may exhibit preferably an expansion that is adjusted to the angle of the cone surface.  
         [0037]     According to another aspect of the present invention, the first section of the feed channel is mounted rotatably in relation to the assigned lamp receptacle. This feature is achieved preferably in that the first section of the feed channel is rotatably beared or mounted in a dosing sleeve that is rigid in relation to the assigned lamp receptacle. The dosing sleeve may comprise the inventive dosing borehole and may form, furthermore, a bearing for the tilt spoon unit and for a central internal part, in which the bypass channel and the inflow orifice(s) are also formed.  
         [0038]     Preferably the first section of the feed channel is formed in a central internal part and is rotatably beared or mounted in a dosing sleeve that is rigid in relation to the assigned lamp receptacle.  
         [0039]     The bypass channel may be formed preferably in the central internal part. One end of said bypass channel empties into the first section of the feed channel. The other end of said bypass channel forms one or more inflow orifice(s) for the entry of a gas stream into the bypass channel.  
         [0040]     In another preferred design the aforementioned covers for closing the inflow orifice(s) in relation to the rigid dosing sleeve are formed stationarily, preferably as one piece with the dosing sleeve.  
         [0041]     In a specific embodiment, the result is that, as the tilt spoon unit is swung in relation to the rigid dosing sleeve, the inflow orifices are brought simultaneously into coincidence with the covers or out of coincidence with the covers. In particular, the result is that in a preparation step the inflow orifices are not covered by the covers so that in the preparation step the gas stream flows through the inflow orifices over the bypass channel past the drop. Not until the fill step are the inflow orifices blocked by the covers by rotating the dosing sleeve in relation to the internal part so that in this way the bypass channel is blocked. Then the gas stream is guided over the dosed volume and drags the drop along with it into the discharge vessel.  
         [0042]     The tilt spoon unit may be provided with an aforementioned gas passage borehole, which aligns with the dosing borehole in the release position of the tilt spoon unit so that the pressure of the fill gas at the gas passage borehole induces or supports the transport of the drop into the feed channel.  
         [0043]     According to another preferred aspect of the present invention, which is also claimed independently, the gas passage borehole may exhibit diverter or deflector means, in particular a diverter or deflector sleeve, in order to keep excess mercury, draining from the dosing unit during the respective dosing operation, away from the gas passage borehole. This prevents the mercury, draining off the tilt spoon unit, from flowing into the gas passage borehole and, thus, also prevents additional mercury from flowing into the feed channel to the exactly pre-dosed drop.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0044]     The invention is described in detail below also with respect to other features and advantages with the aid of the description of the embodiments and with reference to the attached drawings.  
         [0045]      FIG. 1  is a schematic longitudinal sectional view of an embodiment of an inventive lamp receptacle with a dosing unit arranged therein in a first position (preparation step);  
         [0046]      FIG. 2  is a sectional view of the lamp receptacle with a dosing unit arranged therein along the line C-C in  FIG. 1 ;  
         [0047]      FIG. 3  is a sectional view of the lamp receptacle with a dosing unit arranged therein along the line A-A in  FIG. 1 ;  
         [0048]      FIG. 4  is a sectional view of the lamp receptacle with a dosing unit arranged therein along the line B-B in  FIG. 1 ;  
         [0049]      FIG. 5  is a schematic longitudinal sectional view of the embodiment of an inventive lamp receptacle with a dosing unit arranged therein, according to  FIG. 1 , in a second position (fill step);  
         [0050]      FIG. 6  is a sectional view of the lamp receptacle with a dosing unit arranged therein along the line C-C in  FIG. 5 ;  
         [0051]      FIG. 7  is a sectional view of the lamp receptacle with a dosing unit arranged therein, in a sectional view along the line A-A in  FIG. 5 ;  
         [0052]      FIG. 8  is a sectional view of the lamp receptacle with a dosing unit arranged therein, in a sectional view along the line B-B in  FIG. 5 ;  
         [0053]      FIG. 9  is a diagrammatic sketch, which shows an embodiment of the dosing unit with the tilt spoon unit during the rotation of the assigned pump/filling machine, which may be provided with a plurality of lamp receptacles for receiving a respective discharge vessel;  
         [0054]      FIG. 10  is a perspective view of an embodiment of an inventive dosing sleeve;  
         [0055]      FIG. 11  is a top view of a dosing sleeve, according to  FIG. 10 ;  
         [0056]      FIG. 12  is an internal part of the dosing unit, which is illustrated by means of FIGS.  1  to  8 ;  
         [0057]      FIG. 13  is a perspective view of the internal part, according to  FIG. 12 ;  
         [0058]      FIG. 14  is a longitudinal sectional view, which deviates from the drawing in  FIG. 1 , along the line A-A in  FIG. 2  of the inventive lamp receptacle with a dosing unit, arranged therein, in a first position (preparation step) in order to explain the bypass mechanism;  
         [0059]      FIG. 15  is a longitudinal sectional view along the line A-A in  FIG. 6  of the lamp receptacle with a dosing unit, arranged therein, in order to explain the bypass mechanism in the second position of the dosing unit (fill step). 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0060]      FIG. 1  is a longitudinal sectional view of an embodiment of an inventive lamp receptacle  11  in a longitudinal sectional view. The lamp receptacle  11  comprises, first of all, a housing  61  and a holder  43 , which is attached to the housing and in which a discharge vessel  13  of a fluorescent lamp, which is to be produced, is held by way of a pump tube  44 , which is melted onto the discharge vessel. The holder  43  comprises sealing means  45 , which may be made specifically as a ring-shaped sealing rubber.  
         [0061]     The discharge vessel  13  is held on its opposite end in a lamp receptacle by way of a holder. Said lamp receptacle may be formed in a way that is different from the lamp receptacle  11 , which is described here, but which is well-known from the state of the art. The opposite lamp receptacle may evacuate, for example, the discharge vessel  13  by way of a second pump tube, which is melted on the respective end, and/or may support a flushing operation with a fill gas by means of suction. The standard lamp receptacle  11 , which is shown here, comprises an interior  42 , which is flow-connected to the discharge vessel  13  via a feed channel  19 , which runs in particular in a straight line, when the pump tube  44  is installed. The feed channel  19  defines a central axis  50 . The interior  42  of the lamp receptacle  11  may be charged with fill gas by way of a fill gas line  46 , which projects with an entry  60  in the vicinity of the axis  50  of the interior  42 , which is designed so that it is essentially rotationally symmetrical about this axis  50 .  
         [0062]     Furthermore, there is a supply or reservoir of mercury, forming a sea of mercury  47 , inside the interior  42 . The level of the sea of mercury  47  is always sufficiently below the centrally disposed feed channel  19  and the entry  60  of the fill gas line  46 .  
         [0063]     By means of a dosing unit  15  a predetermined amount of mercury may be transferred from the sea of mercury  47  into the central feed channel  19  and then conveyed into the discharge vessel  13  with the aid of a fill gas stream.  
         [0064]     The dosing unit  15  comprises, first of all, a dosing sleeve  38 , which is stationary in relation to the lamp receptacle  11  and which is oriented coaxially in relation to the feed channel  19 , designed in an internal part  41 , and closes said feed channel. The dosing sleeve  38  exhibits an external section  48 , with which it is connected in a rotationally rigid manner to the housing  61  of the lamp receptacle  11 , as well as an internal section  49 , on which a tilt spoon unit  28  is beared or mounted rotatably—as another element of the dosing unit  15 —about the axis  50 , which is defined by the (central) feed channel  19 . By means of an driving or drive type screw  51 , which engages with or traverses an oblong or long stretched-out hole  52  in the dosing sleeve  38 , the tilt spoon unit  28  carries with it the aforementioned internal part  41 , as the third element of the dosing unit  15 , with the rotational movement of the tilt spoon unit  28 .  
         [0065]     The internal part  41  of the dosing unit  15  comprises simultaneously a first section  33  of the feed channel  19  as well as a bypass channel  64 , which empties into this first section  33  of the feed channel  19 . Thus, the first section  33  of the feed channel  19  as well as the bypass channel  64  are beared or mounted rotatably about the axis  50  in relation to the housing of the lamp receptacle  11 . Of course, it is conceivable from a purely theoretical viewpoint to attach the pump tube  44  directly to this first section  33  of the feed channel  19 . However, the feed channel  19  is preferably extended by a second section  34 , which is flow-connected on its one side to the pump tube  44  and is flow-connected on the opposite side to the first section  33 , which is rotatably beared or mounted. The said second section  34  is designed in a stationary manner as a separate component or integrally with the dosing sleeve  38  in relation to the housing of the lamp receptacle  11 .  
         [0066]     According to an independently inventive aspect of the present invention, the first section  33  of the feed channel  19  exhibits a cone surface  35  on its end facing the second section  34  in order to improve the interaction with the second section  34  of the feed channel. Said cone surface engages with the assigned orifice  36  of the second section  34 . Preferably the second section  34  exhibits simultaneously on its orifice  36  an expansion  37 , which is adjusted to the cone surface  35  of the first section  33 , so that the occurrence of an uncontrolled gap, as in the case of the state of the art, is avoided as far as possible.  
         [0067]     The tilt spoon unit  28  can be tilted by rotating the lamp receptacle  11  (a feature that shall be described in detail below with the aid of the explanation with respect to  FIG. 3 ) between a dosing position (preparation step) and a release position (fill step). The dosing position or the release position represents the end positions of a rotational movement of the tilt spoon unit  28  about the axis  50  of the feed channel  19  or rather the dosing sleeve  38 , on which the tilt spoon unit  28  is beared or mounted, as described above. These end positions are defined by means of the dimensions of the oblong hole  52  in the dosing sleeve  38 .  
         [0068]     In  FIG. 2  the lamp receptacle  11  is shown along the line C-C from  FIG. 1 ; in  FIG. 3 , along the line A-A from  FIG. 1 ; and in  FIG. 4 , along the line B-B from  FIG. 1 . In this representation the tilt spoon unit  28  is located in its first position, i.e., the dosing position (preparation step).  
         [0069]     As  FIGS. 2, 3  and  4  show, the tilt spoon unit  28  comprises a spoon  31 , which lies radially outwards in relation to the axis  50  and which is connected to an essentially ring-shaped internal section  53  by way of a scoop arm  30 . In a preferred embodiment the spoon  31 , the scoop arm  30  and the essentially ring-shaped internal section  53  are designed as one piece. By means of the spoon  31 , which is shown in  FIG. 3  as partially broken open, the tilt spoon unit  28  may pick up mercury from the sea of mercury  47  and guide it specifically to a dosing borehole  21  in the dosing sleeve  38  by means of a channel  54  inside the scoop arm  30 . In order to ensure that the dosing borehole  21  is filled with mercury as completely as possible, an outlet  55  is provided in the internal part  41  of the dosing unit  15 . The said outlet  55  of the internal part  41  in the dosing position of the tilt spoon unit  28  aligns with the dosing borehole  21 .  
         [0070]     The end of the dosing sleeve  38  that faces away from the external section  48  also exhibits two covers  65 ,  66 , which project in the axial direction beyond the internal section  49  and form a part of a change-over mechanism  63  (to be explained in detail below) for the gas stream guided into the discharge vessel  13 . The covers  65 ,  66  exhibit an internal surface  67 ,  68 , which is rounded to match the radius of the diverter disk or deflector disk  57  and which slides as close as possible over the outside of the diverter disk  57 . In the release position (fill step) the covers  65 ,  66 , which are formed as anchor necks or anchor palms, projecting beyond the internal section, cover the inflow orifices  56 , which are formed diametrically on the shell side of the diverter disk  57 , in the internal part, so that in the fill step the gas stream is blocked by the bypass channel  64 . In the dosing position (preparation step), however, the internal part  41  and the dosing sleeve  38  are rotated in the opposing direction in such a manner that the covers  65 ,  66  do not cover the diametrically arranged inflow orifices  26  in the diverter disk  57 , so that the gas flow may enter into the bypass channel  64  by way of the inflow orifices  26  and from there may enter into the discharge vessel  13  by way of the first section  33  of the feed channel  19  and the second section  34  of the feed channel  19 . The bypass channel  64  and the first section  33  of the feed channel  19  may be designed as a continuous borehole, which is closed by a cap  69  on the end facing away from the discharge vessel.  
         [0071]     At the same time the T-shaped side channels lead to the two diametrically opposite inflow orifices  26 .  
         [0072]     The process that is controlled by the tilt spoon unit  28  is explained once again below in this context. If, after the dosing borehole  21  is filled with a predetermined amount of mercury, the tilt spoon unit  28  is tilted into the release position (by tilting clockwise out of the dosing position shown in  FIGS. 2, 3  and  4 ), a gas passage borehole  39  in the ring-shaped internal section  53  of the tilt spoon unit  28  moves into an orientation that aligns with the dosing borehole  21 . At the same time this tilting movement of the tilt spoon unit  28  takes with it the internal part  41  of the dosing unit  15  so that even an acceleration channel  25  inside the internal part  41  moves into an aligned orientation with the dosing borehole  21 . At the same time the rotational movement of the internal part  41  closes in relation to the dosing sleeve  38  the inflow orifices  26  of the bypass channel  64  by means of the covers  65 ,  66  so that at this stage the gas flow is guided through the dosing borehole  21  and drags the drop  16  with it into the discharge vessel  13 . This release position, i.e., the position of the dosing unit  15  in the fill step, is illustrated with the aid of FIGS.  5  to  8 .  
         [0073]     In the present embodiment the dosing borehole is formed in the shape of a triangular hole  18 , i.e., as a passage borehole with a triangular cross sectional shape. In the present embodiment the triangle is an isosceles triangle with straight legs. Yet at the same time even diverging shapes are conceivable. One consideration in this design is that the mercury, received in the dosing borehole  21 , forms into a single drop  16 , which has as few contact points as possible with the walls  22  to  24  of the dosing borehole  21 . If, based on the European specifications, one doses with a predetermined maximum amount of mercury of 5 mg or 10 mg (depending on the type of lamp), the calculated diameter of the drop  16 , exhibiting as spherical a shape as possible, is equal to 0.89 mm or 1.12 mm.  
         [0074]     In the release position of the tilt spoon unit  28  the drop  16  of mercury that is formed in the dosing borehole may enter into the acceleration channel  25  of the internal part  41 . In the present embodiment the acceleration channel  25  inside the internal part  41  is arranged at an angle of 45°. Thus, on the one hand, a 90°-transition during transport of the drop  16  from the dosing borehole  21  into the feed channel  19  is avoided, a feature that in the state of the art renders the transport of the mercury difficult. In addition, in the orientation of the acceleration channel  25  that is proposed here, the drop  16  is also accelerated by the force of gravity, acting on said drop, without totally losing this momentum upon entering the feed channel  19 . In addition, transitions  17  between the dosing borehole  21  and the acceleration channel  25  or between the acceleration channel  25  and the feed channel  19  or between the feed channel  19  and the pump tube  44  are designed in such a manner that the drop  16  in the direction of transport does not impinge on any impediment that is designed as steps.  
         [0075]     In addition, in an inventive construction there are a number of measures, which are also claimed independently as inventive, in order to avoid an undesired entry of the mercury past the dosing borehole  21 . First, the internal part  41  of the dosing unit  15  is provided with a diverter mechanism or deflector mechanism  27  on its end facing away from the pump tube  44 . This diverter mechanism  27  is designed to avoid an undesired entry of the mercury, running up the tilt spoon unit  28 , into the inflow orifice  26  of the feed channel  19  that faces away from the pump tube  44 . The diverter mechanism  27  is designed here specifically in the shape of a groove  56 .  
         [0076]     In order to prevent the mercury from running as fast as possible precisely down outsides of the spoon  31 , which is located at the top in the dosing position, another independent aspect of the present invention provides that this topside of the spoon  31  is designed as a roof  32  (cf.  FIG. 1 ), i.e., with surfaces that are sloped or inclined towards the horizontal, so that the mercury may drain off. Finally diverter means or deflector means  40  are also disposed on the gas passage borehole  39 , which is provided in the ring-shaped internal section  53  of the tilt spoon unit  28  and which may be designed here specifically as a projecting sleeve (cf.  FIG. 3 ). This, too, prevents the mercury, draining off the tilt spoon unit  28 , from entering directly into the feed channel  19  without passing the dosing borehole  21 .  
         [0077]     In order to ensure that the tilt spoon unit  28  tilts as fast as possible between the dosing position and the release position, thus creating the defined conditions (in order to have the least possible negative effect on the design of the drop  16  having an essentially spherical shape), the tilt spoon unit  28  is also provided with an additional trim weight  29 , which is fastened on the scoop arm  30  in the vicinity of the spoon  31  by means of a fastening screw  58 .  
         [0078]      FIG. 9  is a schematic sketch of the rotation of the pump/filling machine, to which a plurality of lamp receptacles  11  may be fastened. Thus, the plurality of lamp receptacles  11  rotates about a central rotational axis of the pump/filling machine along a circular path. In so doing, on the one hand, the sea of mercury  47  shifts in the interior  42  of the respective lamp receptacles  11 . At the same time the tilt spoon unit  28  tilts periodically from the dosing position (preparation step) into the release position (fill step) and from the release position back again into the dosing position.  
         [0079]     In the positions A and B, the spoon  31  is totally submerged in the sea of mercury  47  and emerges, filled with mercury in position C, from the sea of mercury  47  so that both the spoon  31  and the channel  54  are filled with mercury. In positions D and E, the tilt spoon unit  28  is still located in the dosing position, where at this stage now the mercury in the channel  54  can flow into the dosing borehole  21 . In positions F and G, the tilt spoon unit  28  is transferred into the release position by a fast tilt motion so that the bead  16  of mercury that has formed in the dosing borehole  21  can enter into the central feed channel  19  by way of the acceleration channel  25  and from there can enter into the discharge vessel  13 .  
         [0080]     This operation is supported by a fill gas thrust, which may be generated, for example, by generating such an underpressure on the opposite side of the discharge vessel in the discharge vessel that at the correct instant at which the bead  16  reaches the entry of the pump tube  44 , a fill gas thrust is passed on from the fill gas line  46  into the feed channel  19  by way of the inflow orifice  26  and/or the gas passage borehole  39 .  
         [0081]     In position H the tilt spoon unit  28  is tilted from the release position back into the dosing position.  
         [0082]      FIG. 10  is a perspective view of the dosing sleeve  38 . The dosing sleeve  38  comprises the aforementioned external section  48  for installing into the housing  61  of the lamp receptacle  11  as well as an internal section  49 , whose outside diameter is smaller. This internal section  49  exhibits the aforementioned oblong hole  52  as well as the dosing borehole  21 , formed with a triangular cross section.  FIG. 11  is a side view of the dosing sleeve  38  in  FIG. 10 .  
         [0083]      FIG. 12  is a side view, and  FIG. 13  is a perspective side view of the internal part  41  of the dosing unit  15 . The internal part  41  comprises the aforementioned first section  33  of the feed channel  19 . In order to connect to the second section  34  of the feed channel  19 , the internal part  41  exhibits the aforementioned cone surface  35  on its one face-sided end or frontal end. On its opposite end the central, continuous first section  33  of the feed channel  19  exhibits the inflow orifice  26 , which was also mentioned above and which is shielded as well as possible against an undesired inflow of mercury by means of the groove  56 , comprising the diverter means  27  and the diverter disk  57 . Starting from the shell surface of the internal part  41 , the acceleration channel  25  extends at a 45° angle in the direction of the first section  33  of the feed channel  19 . Furthermore, there is a borehole  59  for receiving the driving screw  51  (not illustrated here) as well as the outlet  55  for carrying away the mercury in the filling process of the dosing borehole  21  of the assigned dosing sleeve  38 .  
         [0084]      FIGS. 14 and 15  are sectional views that are different from the drawings in  FIGS. 1 and 5  in order to illustrate how the change-over mechanism  63  works. The change-over mechanism comprises the diametrically arranged inflow orifices  26  in the internal part  41  as well as the covers  65 ,  66 , which are made as one piece with the dosing sleeve  38 .  FIG. 14  illustrates the dosing position (preparation step). In this position the change-over mechanism  63  guides the gas stream through the inflow orifices  26  and the bypass channel  64  past the dosing borehole  21 , which is configured as a triangular hole  18 .  
         [0085]      FIG. 15  shows the arrangement in the release position (fill step). In this position of the change-over mechanism  63  the covers  65 ,  66  close the inflow orifices  26  of the bypass channel in such a manner that at this stage the gas stream is guided over the dosed volume or rather the dosing borehole  21  and in this way drags the drop  16  with it into the discharge vessel  13 .  
         [0086]     With the dosing unit proposed here, or rather the method proposed here, the absolute amount of mercury per lamp may be dosed with significantly higher accuracy and reliability. Owing to the small scattering as compared to the conventional liquid dosing method, an underdosing and any resulting early failure of the lamp due to such a scattering may be avoided. Furthermore, an inadvertent overdosing is avoided with significantly higher certainty.

Technology Category: 5