Patent Publication Number: US-2010123393-A1

Title: Hid lamp with a canted arc tube

Description:
The technical field of this disclosure is high intensity discharge (HID) lamps, particularly, an HID lamp with a canted arc tube. 
     In the majority of HID lamps, the arc tube is arranged in the outer envelope aligned with the lamp axis. The outer envelope has a bulbous portion surrounding the arc tube, and an elongate neck portion extending from the bulbous portion. The arc tube is normally supported in the lamp envelope by a support frame fixed to rigid current-supply conductors extending from the lamp stem through the neck portion of the outer envelope. 
     The burning orientation of the arc tube in HID lamps affects the efficiency of the lamps. It has been found that a vertical burning position of the arc tube is most efficient, followed by a horizontal burning position. However, in certain lamp applications, it is not practicable to orient the outer bulb in a horizontal or vertical position. For example, in portable light towers for illuminating sports playing fields, the design and position of the reflector for illuminating the playing field limits the orientation of the outer bulb to a base-up orientation with the bulb axis between the vertical and horizontal. Thus, such luminaires would support the arc tube at an angle which is less efficient than the preferred vertical or horizontal burning positions. As a result, prior art lamps having an arc tube aligned with the lamp axis do not provide optimum light distribution or efficiency when operated in such luminaires. 
     One solution has been to provide a lamp in which the arc tube is supported in the outer envelope at a predetermined angle with respect to the lamp axis. For sports lighting applications, the arc tube is canted such that it would be in a horizontal burning position when secured in a luminaire. However, in lamps having an arc tube canted more than only a few degrees from the lamp axis, the configuration of the frame for supporting the arc tube has prevented the insertion of the frame and arc tube through the elongate neck portion of the standard bulged-tube (BT) outer envelope. 
     The present generation of HID lamps with canted arc tubes requires complex configurations and/or assembly methods. One approach has been to sever the elongate neck portion from the outer envelope, insert the arc tube assembly into the outer envelope, and reattach the elongate neck portion to the outer envelope. This adds steps to and increases the complexity of the assembly process. Another approach has been to provide rotary joints in an articulated frame holding the arc tube, so that the arc tube assembly is in a generally linear configuration when inserted through the elongate neck portion into the outer envelope. Once in the outer envelope, the articulated portions of the frame are rotated at the rotary joints to achieve the canted arc tube, and locking the rotary joints are locked in place. Unfortunately, the rotary joints present a number of problems. The rotary joints increase the resistance of the frame, reducing lamp efficiency. A shunt strap may be required in parallel with the rotary joint to assure sufficient current carrying capacity. Installation of the rotary joints and shunt straps in the frame increases the number of fabrication steps, increasing costs. Rotary joints can also increase the rejection rate for defective lamps, since the rotary joint may not lock properly. The rotary joints also increase the number of parts that must be stocked and handled. 
     It would be desirable to have an HID lamp with a canted arc tube that would overcome the above disadvantages. 
     One aspect of the present invention provides a high intensity discharge (HID) lamp including an outer envelope having a neck portion and a lamp axis; a frame having a first frame section, a second frame section, a third frame section, the first frame section being pivotably connected to the second frame section in a first connection, and the second frame section being pivotably connected to the third frame section in a second connection; and an arc tube having an arc tube axis, the arc tube being attached to the second frame section. At least one of the first connection and the second connection is a deformable connector paired with a rotary joint; and the arc tube axis forms a predetermined angle with the lamp axis when the frame is in a final configuration in the outer envelope. 
     Another aspect of the present invention provides a high intensity discharge (HID) lamp including an outer envelope having a neck portion and a lamp axis; a frame having a first frame section, a second frame section, a third frame section, a first pair of rotary joints pivotably connecting the first frame section and the second frame section, a second pair of rotary joints pivotably connecting the second frame section and the third frame section; and an arc tube having an arc tube axis, the arc tube being attached to the frame between the first pair of rotary joints and the second pair of rotary joints. The first pair of rotary joints and the second pair of rotary joints are selected from the group consisting of one piece rotary joints, pinned rotary joints, and tabbed rotary joints; and the arc tube axis forms a predetermined angle with the lamp axis when the frame is in a final configuration in the outer envelope. 
     Another aspect of the present invention provides a high intensity discharge lamp including an outer envelope having a neck portion and a lamp axis; a fixed frame having a first bend and a second bend opposite the first bend; and an arc tube having an arc tube axis, the arc tube being attached to the fixed frame between the first bend and the second bend. The fixed frame is so dimensioned as to be insertable through the neck portion; and the arc tube axis forms a predetermined angle with the lamp axis when the fixed frame is in a final configuration in the outer envelope. 
    
    
     
       The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention, rather than limiting the scope of the invention being defined by the appended claims and equivalents thereof. 
         FIG. 1  is a perspective view of an HID lamp with a canted arc tube according to the present invention; 
         FIGS. 2A-2D  are exploded, bottom, side unlocked, and side locked views of a rotary joint for an HID lamp with a canted arc tube according to the present invention; 
         FIGS. 3A-3E  are first part side, second part side, bottom exploded, side locked and bottom locked views of another rotary joint for an HID lamp with a canted arc tube according to the present invention; 
         FIG. 4A-4F  are first part side, first part bottom, second part side, second part bottom, side unlocked, and side locked views of another rotary joint for an HID lamp with a canted arc tube according to the present invention; 
         FIG. 5  is a perspective view of another HID lamp with a canted arc tube according to the present invention; 
         FIG. 6  is an exploded view of another rotary joint for an HID lamp with a canted arc tube according to the present invention; 
         FIG. 7  is an exploded view of another rotary joint for an HID lamp with a canted arc tube according to the present invention; 
         FIGS. 8A &amp; 8B  are top and side schematic views of an arc tube assembly for an HID lamp with a canted arc tube according to the present invention; 
         FIGS. 9A &amp; 9B  are side and end schematic views of an arc tube assembly being inserted into the neck portion of an outer envelope of an HID lamp with a canted arc tube according to the present invention; 
         FIGS. 10A &amp; 10B  are side and top views of another HID lamp with a canted arc tube according to the present invention; and 
         FIGS. 11A &amp; 11B  are side and top views of another HID lamp with a canted arc tube according to the present invention. 
     
    
    
       FIG. 1  is a perspective view of an HID lamp with a canted arc tube according to the present invention. In this embodiment, the HID lamp employs rotary joints as described below for  FIGS. 2-4 , such as one piece rotary joints, pinned rotary joints, and/or tabbed rotary joints. 
     Referring to  FIG. 1 , metal halide HID lamp  30  has a standard bulged-tube (BT) glass outer envelope  1  in which an arc tube  4 , such as a metal halide arc tube, is mounted at a predetermined angle with respect to the lamp axis  32 . In one example, the outer envelope  1  is a BT56 glass outer envelope and the predetermined angle is about 30 degrees. The tubular quartz arc tube  4  includes pinch seals  5  at opposite ends which seal the arc tube  4  in a gas-tight manner, discharge electrodes  6   a,    6   b,  and a starting electrode  6   c.  The arc tube  4  has an arc tube axis  33 . Stem  7  includes rigid current-supply conductors  13 ,  14  extending from the stem press and connected to current-supply wires (not shown). The pair of current-supply conductors  13 ,  14  are also connected to respective pair of rotary joints  20 ,  21 . A skirt portion (not shown) of the stem  7  is sealed to the neck portion  34  of the outer envelope  1  in a gas-tight manner. The current supply wires are connected to appropriate contact portions of lamp cap  2 . Frame  9  is secured to the stem  7  and holds the arc tube  4  at the predetermined angle with respect to the lamp axis  32 . In one embodiment, the predetermined angle between the arc tube axis  33  and the lamp axis  32  is about 30 degrees. The frame  9  also electrically connects the current-supply conductors  13 ,  14  with the discharge electrodes  6   a,    6   b  and starting electrode  6   c.  The arc tube  4  and the frame  9  form an arc tube assembly as defined herein. Those skilled in the art will appreciate that the current-supply conductors  13 ,  14  can be formed of separate lengths of wire welded together as desired for a particular application. 
     The frame  9  has three frame sections  9   a - 9   c  which are pivotable with respect to each other and connected with rotary joints. The rotary joints are lockable to maintain the predetermined angle between the arc tube  4  and the lamp axis  32  once the frame  9  is installed in the outer envelope  1  in the final configuration. The rotary joints are also electrically conductive. The first frame section  9   a  includes the current-supply conductors  13 ,  14 . The second frame section  9   b  includes one rigid conductor  15   b  which extends along one side of the arc tube  4 , an upper short conductor  16   b,  and a lower short conductor  16   a.  Each of the short conductors  16   a,    16   b  are adjacent one of the pinch seals  5  of the arc tube  4  and are secured thereon by metallic bands  17 . A quartz glass tube  18  encloses the rigid conductor  15   b  and electrically insulates the rigid conductor  15   b  from the opposing upper short conductor  16   b.  The first frame section  9   a  is pivotably connected to the second frame section  9   b  with the connection of the current-supply conductor  13  to the rigid conductor  15   b  through rotary joint  20  and the connection of the current-supply conductor  14  to the lower short conductor  16   a  through rotary joint  21 . The third frame section  9   c  is a single generally U-shaped rigid wire including legs  15   c,    16   c  connected with crossbar  36 . The third frame section  9   c  is pivotably connected to the second frame section  9   b  through the pair of rotary joints  22 ,  23  with the connection of the leg  15   c  to the rigid conductor  15   b  through the rotary joint  22  and the connection of the leg  16   c  to the upper short conductor  16   b  through the rotary joint  23 . In one embodiment, a shunt strap can be connected in parallel with one or more of the rotary joints as desired to assure current carrying capacity. 
     Resilient bars maintain the position of the frame  9  in the outer envelope  1 . Lower resilient bars  38 ,  40  connected to the respective current-supply conductors  13 ,  14  of the first frame section  9   a  contact the inside surface of the neck portion  34  of the outer envelope  1 . Upper resilient bars  42 ,  44  connected to the respective legs  15   c,    16   c  of the third frame section  9   c  contact the inside surface of protruding domed portion  1   c  of the outer envelope  1 . 
     The electrical connection to the arc tube  4  is provided through the frame  9  and the rotary joints. The path from the lamp cap  2  to the discharge electrode  6   b  includes the current-supply conductor  14  and metallic strap  8   b  connected to the discharge electrode  6   b.  The starting electrode  6   c  is connected to the current-supply conductor  14  through a resistor and bimetal switch (not shown). The path from the lamp cap  2  to the discharge electrode  6   a  includes the current-supply conductor  13 , rotary joint  20 , rigid conductor  15   b,  and metallic strap  8   a  connected to the discharge electrode  6   a.  In one embodiment, an electrical shunt (not shown) can be connected across the rotary joint  20  between the current-supply conductor  13  and the rigid conductor  15   b  to ensure current flow to the discharge electrode  6   a.    
     During manufacture, the three frame sections  9   a - 9   c  of the frame  9  are aligned so that the frame  9  can pass through the neck portion  34  of the outer envelope  1 . The rotary joints  20 - 23  allow a larger angle between frame sections than the angle in the final configuration. When the upper resilient bars  42 ,  44  have been placed in the domed portion  1   c  of the outer envelope  1 , the three frame sections  9   a - 9   c  can be rotated relative to each other until the rotary joints  20 - 23  lock, fixing the predetermined angle between the arc tube  4  and the lamp axis  32 . 
       FIGS. 2A-2D  are exploded, bottom, side unlocked, and side locked views of a rotary joint for an HID lamp with a canted arc tube according to the present invention. The rotary joint  50 , which is defined herein as a one piece rotary joint, includes a disk  52  forming a hole  54 , a lock  56 , and a stop  58 ; a connector/frame  60  forming a bend  62  with a tip  64 ; and a retaining washer  66 . The disk  52  can be formed from a single piece. The tip  64  of the connector/frame  60  passes through the hole  54  of the disk  52  and is secured in place by the retaining washer  66 , so that the connector/frame  60  can rotate about the hole  54  along the face of the disk  52  between the lock  56  and the stop  58 . The connector/frame  60  is receivable in the lock  56  to lock the connector/frame  60  at the desired angle relative to connector/frame  68 . The optional stop  58  limits rotation of the connector/frame  60  when the rotary joint  50  is not locked, i.e., before the connector/frame  60  is locked in the lock  56 . The retaining washer  66  maintains the connector/frame  60  in electrical contact with the disk  52 . The disk  52  of the rotary joint  50  can be welded to connector/frame  68 . The connector/frames  60 ,  68  can be part of the frame of the arc tube assembly or can be a separate part that is assembled into the frame. 
     During manufacture of the HID lamp, the arc tube assembly is placed through the neck portion of the outer envelope with the rotary joint  50  in the unlocked configuration of  FIG. 2C . The stop  58  limits the angle of rotation of the connector/frame  60 , limiting the angle between the connector/frame  60  and the connector/frame  68  during installation. When the arc tube assembly is in place in the outer envelope, the connector/frames  60 ,  68  are rotated relative to each other until the rotary joint  50  is in the permanently locked configuration of  FIG. 2D . The connector/frame  60  is held between resilient sides of the lock  56  in the locked configuration. 
       FIGS. 3A-3E  are first part side, second part side, bottom exploded, side locked and bottom locked views of another rotary joint for an HID lamp with a canted arc tube according to the present invention. The rotary joint  70 , which is defined herein as a pinned rotary joint, includes a first disk  72  forming a connection hole  74 , a first alignment hole  76 , and a first locking hole  78 ; a first connector/frame  96 ; a second disk  82  forming a connection cuff  84 , a second alignment hole  86 , and a second locking hole  88 ; and a second connector/frame  90  forming a bend  92  with a tip  94 . The connection hole  74  of the first disk  72  is mateable with and rotatable about the connection cuff  84  of the second disk  82 , allowing the first disk  72  to rotate relative to the second disk  82 . The edge of the connection cuff  84  can be rolled to retain the first disk  72  on the second disk  82 . The second connector/frame  90  is connected to the second disk  82  so that the tip  94  of the second connector/frame  90  passes through the second locking hole  88 . The second connector/frame  90  is attached to the second disk  82  so that the resilience of the second connector/frame  90  and/or the second disk  82  urges the tip  94  through the second locking hole  88  toward the first disk  72 . When the rotary joint  70  is in the locked configuration, the second locking hole  88  is aligned with the first locking hole  78 , so the tip  94  passes through both the second locking hole  88  and the first locking hole  78  to prevent rotation of the first disk  72  relative to the second disk  82 . The first disk  72  can be welded to the first connector/frame  96 . The first connector/frame  96  and the second connector/frame  90  can be part of the frame of the arc tube assembly or can be a separate part that is assembled into the frame. 
     During manufacture of the HID lamp, the arc tube assembly is placed through the neck portion of the outer envelope with the rotary joint  70  in the unlocked configuration and rotated into the locked configuration of  FIGS. 3D &amp; 3E . The first alignment hole  76  of the first disk  72  and the second alignment hole  86  of the second disk  82  are initially aligned to indicate the proper angle between the first connector/frame  96  and the second connector/frame  90  during installation. When the arc tube assembly is in place in the outer envelope, the first connector/frame  96  and the second connector/frame  90  are rotated relative to each other until the first locking hole  78  and the second locking hole  88  are aligned, so that the tip  94  of the second connector/frame  90  passes through both the second locking hole  88  and the first locking hole  78 . This places the rotary joint  70  in a permanently locked configuration. 
     Those skilled in the art will appreciate that the first disk  72  and the second disk  82  can form additional locking holes as desired for a particular application. The additional locking holes can be located across the connection hole  74  from the first locking hole  78  and the second locking hole  88 . The first connector/frame  96  is bent to form a tip which passes through the additional locking holes when the additional locking holes are aligned, further locking the rotary joint  70  in the permanently locked configuration in addition to the locking provided by the tip  94 , the second locking hole  88 , and the first locking hole  78 . 
       FIG. 4A-4F  are first part side, first part bottom, second part side, second part bottom, side unlocked, and side locked views of another rotary joint for an HID lamp with a canted arc tube according to the present invention. The rotary joint  100 , which is defined herein as a tabbed rotary joint, includes a first disk  102  forming a connection hole  104 , an alignment tab  106 , and an opposed tab pair  108 ; a first connector/frame  126 ; a second disk  112  forming a connection cuff  114 , an alignment hole  116 , and a hole pair  118 ; and a second connector/frame  120 . The connection hole  104  of the first disk  102  is mateable with and rotatable about the connection cuff  114  of the second disk  112 , allowing the first disk  102  to rotate relative to the second disk  112 . The edge of the connection cuff  114  can be rolled to retain the first disk  102  on the second disk  112 . The first connector/frame  126  and the second connector/frame  120  can be connected to the first disk  102  and the second disk  112 , respectively. The first connector/frame  126  and the second connector/frame  120  can be part of the frame of the arc tube assembly or can be a separate part that is assembled into the frame. When the rotary joint  100  is in the unlocked configuration, the optional alignment tab  106  of the first disk  102  can spring into the optional alignment hole  116  of the second disk  112 , limiting the rotation of the first disk  102  relative to the second disk  112  when the alignment tab  106  is aligned with the alignment hole  116 . When the rotary joint  100  is in the locked configuration, the opposed tab pair  108  of the first disk  102  can spring into the hole pair  118  of the second disk  112 . The rotary joint  100  locks because the two tabs of the opposed tab pair  108  are directed toward each other in opposed directions and mateable with the hole pair  118 , so that each tab prevents rotation in one direction, i.e., one prevents clockwise rotation and the other prevents counterclockwise rotation when the opposed tab pair  108  is aligned with the hole pair  118 . 
     During manufacture of the HID lamp, the arc tube assembly is placed through the neck portion of the outer envelope with the rotary joint  100  in the unlocked configuration of  FIG. 4E  and rotated into the locked configuration of  FIG. 4F . The alignment tab  106  is initially seated in the alignment hole  116  to assure the proper angle between the first connector/frame  126  and the second connector/frame  120  during installation. When the arc tube assembly is in place in the outer envelope, the first connector/frame  126  and the second connector/frame  120  are rotated relative to each other until the opposed tab pair  108  seats in the hole pair  118 . This places the rotary joint  100  in a permanently locked configuration. 
     Those skilled in the art will appreciate that the rotary joints described above in  FIGS. 2-4  above can be modified as desired for a particular application. For example, different angles for the connector/frames in the locked and unlocked configuration and between the connector/frames can be desirable for different applications. The relative positions of the components determining the angle in the unlocked configuration and the locked configuration can be selected as desired, such as the relative position of the lock and stop of the one piece rotary joint; the alignment holes and locking holes of the pinned rotary joint; and the alignment tab, opposed tab pair, alignment hole, and hole pair of the tabbed rotary joint. In another example, a shunt strap can be connected in parallel with one or more of the rotary joints as desired to assure current carrying capacity. 
       FIG. 5 , in which like elements share like reference numbers with  FIG. 1 , is a perspective view of another HID lamp with a canted arc tube according to the present invention. In this embodiment, the HID lamp employs a first connection including one rotary joint and one deformable connector to connect the first frame section to the second frame section and a second connection including one rotary joint and one deformable connector to connect the second frame section to the third frame section. The rotary joints can be one piece rotary joints, pinned rotary joints, and/or tabbed rotary joints as described above for  FIGS. 2-4  or single slotted rotary joints and/or double slotted rotary joints as described below for  FIGS. 6 &amp; 7 . In one embodiment, only one of the first connection or the second connection has a rotary joint and a deformable connector and the other connection has a different configuration, such as two rotary joints or two deformable connectors. 
     Referring to  FIG. 5 , the first frame section  9   a  of the HID lamp  430  is pivotably connected to the second frame section  9   b  with the connection of the current-supply conductor  13  to the rigid conductor  15   b  through deformable connector  130  and the connection of the current-supply conductor  14  to the lower short conductor  16   a  through rotary joint  21 . The third frame section  9   c  is pivotably connected to the second frame section  9   b  with the connection of the leg  15   c  to the rigid conductor  15   b  through deformable connector  132  and the connection of the leg  16   c  to the upper short conductor  16   b  through rotary joint  23 . The deformable connectors  130 ,  132  can be a bendable portion of the frame  9  made of an electrically conductive soft metal, such as aluminum, tantalum, nickel, alloys thereof, or the like. In one embodiment, the deformable connectors  130 ,  132  can be thinner that the frame section in which the deformable connectors are installed to assure that the deformable connector bends rather than the frame. Those skilled in the art will appreciate that the position of the rotary joint and the deformable connector joining a pair of frame sections can be reversed as desired for a particular application, e.g., the rotary joint connecting the first frame section  9   a  to the second frame section  9   b  could be connected to the current-supply conductor  13  or the current-supply conductor  14 . In one embodiment, the rotary joints connect portions of the frame which do not carry current to assure that no shunt strap is required across the rotary joint. In another embodiment, a shunt strap is electrically connected in parallel with the rotary joint  21 ,  23 . 
     During manufacture, the three frame sections  9   a - 9   c  of the frame  9  are aligned so that the frame  9  can pass through the neck portion  34  of the outer envelope  1 . The rotary joints  21 ,  23  and the deformable connectors  130 ,  132  allow a larger angle between frame sections than the angle in the final configuration. When the upper resilient bars  42 ,  44  have been placed in the domed portion  1   c  of the outer envelope  1 , the three frame sections  9   a - 9   c  can be rotated relative to each other to lock the rotary joints  21 ,  23  and bend the deformable connectors  130 ,  132 , fixing the predetermined angle between the arc tube  4  and the lamp axis  32 . 
       FIG. 6  is an exploded view of another rotary joint for an HID lamp with a canted arc tube according to the present invention. The rotary joint can be used as described above for  FIG. 5 . Referring to  FIG. 6 , the rotary joint  138 , which is defined herein as a double slotted rotary joint, includes two thin metallic disks  140 ,  141 . The disk  141  has a central aperture with a cuff  146  which extends through aperture  147  in disk  140  and is rolled outwards to secure the two disks together and to permit relative rotation of the two disks  140 ,  141 . The cuff  146  can be formed by piercing and extruding the disk  140  to form a flanged hole. The disk  141  has two diametrically opposite slots  143  and disk  140  has two diametrically opposite tabs  144  bent out of the plane of the disk  140 . The tabs  144  and slots  143  pivot and lock the two disks  140 ,  141  during lamp assembly. Each disk  140 ,  141  also has a straight cupped portion  145  extending therefrom which matches the contour of the joined frame conductors to permit an easier and more secure weld. 
       FIG. 7  is an exploded view of another rotary joint for an HID lamp with a canted arc tube according to the present invention. The rotary joint can be used as described above for  FIG. 5 . Referring to  FIG. 7 , the rotary joint  148 , which is defined herein as a single slotted rotary joint, includes two thin metallic disks  150 ,  151 . The disks  150 ,  151  can be secured together with a rivet  156  to permit relative rotation. The disk  151  has a slot  153  and disk  150  has a tab  154  bent out of the plane of the disk  150 . The tab  154  and slot  153  pivot and lock the two disks  150 ,  151  during lamp assembly. In this embodiment, the disks  150 ,  151  are welded to the frame section without a cupped portion. 
       FIGS. 8A &amp; 8B  are top and side schematic views of an arc tube assembly for an HID lamp with a canted arc tube according to the present invention. In this embodiment, the arc tube assembly employs a fixed frame without rotary joints or bendable portions. The arc tube assembly is so dimensioned as to be insertable through the neck portion of an outer envelope. 
     The arc tube assembly  170  includes a fixed frame  172  and an arc tube  190 . The fixed frame  172  has a first frame section  174 , a second frame section  176 , and a third frame section  178 , with a first bend  180  between the first frame section  174  and the second frame section  176 , and a second bend  182  between the second frame section  176  and the third frame section  178 . The arc tube  190  is attached to the fixed frame  172  between the first bend  180  and the second bend  182 . The first bend  180  is opposite the second bend  182 , i.e., the first bend  180  and the second bend  182  open in opposite directions. In this embodiment, the first bend  180  and the second bend  182  are the clearance points which contact the inside of the neck portion of the outer envelope when the arc tube assembly  170  is inserted through the neck portion. Clearance points as defined herein are the points of the arc tube assembly which contact the inside of the neck portion of the outer envelope when the arc tube assembly is inserted through the neck portion. The arc tube assembly  170  is narrow at the clearance points so that the arc tube assembly  170  has room to rotate through the neck portion. The arc tube  190  has an arc tube axis  192 , which forms a predetermined angle θ to the lamp axis  194  when the fixed frame  172  is in a final configuration in the outer envelope. In one example, the predetermined angle is about 30 degrees. 
       FIGS. 9A &amp; 9B , in which like elements share like reference numbers with  FIGS. 8A &amp; 8B , are side and end schematic views of an arc tube assembly being inserted into the neck portion of an outer envelope of an HID lamp with a canted arc tube according to the present invention. In this example, the first bend is the clearance point as the arc tube assembly is being rotated through the neck portion of the outer envelope. 
     Referring to  FIG. 9A , the arc tube assembly  170  has been partially inserted into the outer envelope  200 , which includes a globe portion  202  and a neck portion  204 . The neck portion  204  has a neck entrance  208  and a neck exit  206 . The outer envelope  200  can also include a flared portion (not shown) at the neck entrance  208  which can be present when the arc tube assembly is being placed within the outer envelope  200  and then removed or remodeled for fitting of a lamp cap. The arc tube  190  and second frame section  176  are passing through the neck exit  206  with the arc tube  190  in contact with the lower edge of the neck exit  206 . The first frame section  174  is passing through the neck entrance  208  with the first frame section  174  in contact with the lower edge of the neck entrance  208 . The first bend  180  is the clearance point and is in contact with the inside of the upper portion of the neck portion  204 . The clearance point moves along the upper portion of the neck portion  204  toward the neck exit  206  as the arc tube assembly  170  is inserted. 
     Referring to  FIG. 9B , the first bend  180 , i.e., the clearance point, is able to be near the upper portion  210  of the neck portion  204  because of the narrowness of the width W of the first frame section  174 . The narrower the width W, the closer the first bend  180  to the upper portion  210 , which provides more room to maneuver the arc tube assembly  170  through the neck portion  204  and/or the opportunity to design the first bend  180  to be more acute. 
     Those skilled in the art will appreciate that the dimensions of the arc tube assembly can be selected to suit a particular application, so that the arc tube assembly is insertable through the neck portion of the outer envelope. The narrower the clearance point in contact with the inside of the neck portion when the arc tube assembly is being rotated through the neck portion, the more acute the bend can be. Similarly, the narrower the portion of the fixed frame and/or arc tube in contact with the neck entrance or neck exit when the arc tube assembly is being rotated through the neck portion, the more acute the bend can be. In one embodiment, the bend is offset from the arc tube axis, so that the arc tube pinch seal is the clearance point. In another embodiment, the first frame section and/or third frame section include curves and/or steps to allow more room between the frame section and the neck entrance or neck exit when the arc tube assembly is being rotated through the neck portion. 
       FIGS. 10A &amp; 10B  are side and top views of another HID lamp with a canted arc tube according to the present invention. In this embodiment, the fixed frame of the arc tube assembly is so dimensioned as to be insertable through the neck portion of the outer envelope. A bend in the fixed frame is the clearance point that contacts the inside of the neck portion when the fixed frame is inserted through the neck portion during installation of the arc tube assembly. 
     The HID lamp  230  includes an outer envelope  240  and an arc tube assembly  250  located within the outer envelope  240 . The outer envelope  240  having a lamp axis  290  includes a globe portion  242 , a neck portion  244 , and a domed portion  246 . A lamp cap  248  provides the electrical connection to the HID lamp  230 . The arc tube assembly  250  includes a fixed frame  252 , and an arc tube  270  having an arc tube axis  292 . The fixed frame  252  has a first frame section  254 , a second frame section  256 , and a third frame section  258 , with a first bend  260  between the first frame section  254  and the second frame section  256 , and a second bend  262  between the second frame section  256  and the third frame section  258 . In this example, the second frame section  256  is enclosed in an insulating tube. The first frame section  254  includes a number of steps to allow the rigid arc tube assembly  250  to pass through the neck portion  244  and achieve the desired angle with the lamp axis  290 . Those skilled in the art will appreciate that the first frame section  254  and/or the third frame section  258  can include steps and/or curves to increase the maneuverability of the fixed frame  252  through the neck portion  244 , as long as the angle between the arc tube axis  292  and the lamp axis  290  is the desired predetermined angle. In one embodiment, the predetermined angle between the arc tube axis  292  and the lamp axis  290  in the final configuration of the HID lamp  230  is about 30 degrees. A leaf spring  272  fixed to or pivotably attached about the third frame section  258  maintains the position of the arc tube assembly  250  in the domed portion  246 . Leaf springs  274  attached to the first frame section  254  maintain the position of the arc tube assembly  250  in the neck portion  244 . 
     In this embodiment, one or both of the first bend  260  and the second bend  262  are the clearance points during installation of the arc tube assembly  250  in the outer envelope  240 . The second frame section  256  is longer than the arc tube  270 , so the first bend  260  and the second bend  262  extend beyond the arc tube  270 . The widths of the first bend  260  and the second bend  262  are selected so the fixed frame  252  is insertable through the neck portion  244 . Those skilled in the art will appreciate that the one or both of the first bend  260  and the second bend  262  can be rigid to maintain a constant angle when inserted through the neck portion  244 , i.e., the angle of the bend remains constant and does not increase or decrease. In another embodiment, one or both of the first bend  260  and the second bend  262  can be resilient, so that the angle of the bend changes slightly, such as increasing or decreasing, when passing through the neck portion  244  and returns to the original bend angle once inside the outer envelope  240 . 
       FIGS. 11A &amp; 11B  are side and top views of another HID lamp with a canted arc tube according to the present invention. In this embodiment, the fixed frame of the arc tube assembly is so dimensioned as to be insertable through the neck portion of the outer envelope. The pinch seal of the arc tube is the clearance point that contacts the inside of the neck portion when the fixed frame is inserted through the neck portion during installation of the arc tube assembly. 
     The HID lamp  330  includes an outer envelope  340  and an arc tube assembly  350  located within the outer envelope  340 . The outer envelope  340  includes a globe portion  342 , a neck portion  344 , and a domed portion  346 . The arc tube assembly  350  includes a fixed frame  352  and an arc tube  370 . The fixed frame  352  has a first frame section  354 , a second frame section  356 , and a third frame section  358 , with a first bend  360  between the first frame section  354  and the second frame section  356 , and a second bend  362  between the second frame section  356  and the third frame section  358 . In one embodiment, the predetermined angle between the arc tube axis  392  and the lamp axis  390  in the final configuration of the HID lamp  330  is about 30 degrees. In this example, the second frame section  356  is enclosed in an insulating tube and is at a desired angle to the arc tube axis  392 . Angling the second frame section  356  off the arc tube axis  392  can be used to reduce shadowing of the arc tube  370  by the second frame section  356 . 
     A leaf spring  372  attached to the third frame section  358  is receivable in and maintains the position of the arc tube assembly  350  in the domed portion  346 . The leaf spring  372  is pivotably attached about the end portion  359  of the third frame section  358  so that the leaf spring  372  can follow the contour of the interior of the outer envelope  340  as the leaf spring  372  enters the globe portion  342  from the neck portion  344  of the outer envelope  340  when the arc tube assembly  350  is being inserted into the outer envelope  340 . U-shaped springs  374  attached to the first frame section  354  of the fixed frame  352  maintain the position of the arc tube assembly  350  in the neck portion  344 . The U-shaped springs  374  can be aligned to spring against the neck portion  344 . The arc tube  370  includes a first pinch seal  382  near the first bend  360  and a second pinch seal  386  near the second bend  362 . The arc tube  370  is attached to the fixed frame  352  with metallic bands  380 ,  384 . 
     In this embodiment, the bends  360 ,  362  are located off the arc lamp axis  392 , so one or both of the pinch seals  382 ,  386  at the ends of the arc tube  370  are the clearance points during installation of the arc tube assembly  350  in the outer envelope  340 . The bends  360 ,  362  are nearer the lamp axis  390  than their respective pinch seals  382 ,  386 . The widths of the pinch seals  382 ,  386  determine the dimensions of the fixed frame  352  that can be inserted through the neck portion  344 . 
     Those skilled in the art will appreciate that the arc tube assembly can optionally be flexible and/or include flexible portions as desired for a particular purpose. In one example, one or more of the bends in the fixed frame can be resilient so the angle of the bend opens while the bend is the clearance point passing through the neck portion of the outer envelope. In another example, the one or more of the frame sections can be resilient so arc tube assembly becomes flatter, i.e., more linear, as the frame section passes through the neck portion of the outer envelope. Lubricants and/or coatings can also be applied to the outer envelope and/or the arc tube assembly so that the arc tube assembly slides more easily through the neck portion. In one example, the interior of the outer envelope can be coated with AP-5 glass coating. 
     While the embodiments of the invention disclosed herein are presently considered to be preferred, various changes and modifications can be made without departing from the scope of the invention. The scope of the invention is indicated in the appended claims, and all changes that come within the meaning and range of equivalents are intended to be embraced therein.