Abstract:
A lamp—suitable for use within a projector or other high-light output application—includes an ultra high pressure bulb. An extension from the bulb defines a start-up bubble. A conductor is carried by the extension of the ultra high pressure bulb, generally enclosing the start-up bubble, thereby exciting gas contained within the start-up bubble. A header defines a socket within which the extension and the conductor are carried.

Description:
RELATED APPLICATIONS 
   This patent application is related to U.S. patent application Ser. No. 10/769,325, titled “Replacement Lamp Assembly Having a Cap”, filed on Jan. 30, 2004, commonly assigned herewith, and hereby incorporated by reference. 
   This patent application is related to U.S. patent application Ser. No. 10/769,613, titled “A Replacement Lamp Header For Positioning a Lamp Within a Reflector Assembly”, filed on Jan. 30, 2004, commonly assigned herewith, and hereby incorporated by reference. 
   This patent application is related to U.S. patent application Ser. No. 10/769,322, titled “Datum Structure for Ensuring Alignment of a Lamp Assembly”, filed on Jan. 30, 2004, commonly assigned herewith, and hereby incorporated by reference. 
   BACKGROUND 
   Ultra-high pressure lamp innovations have produced one of the brightest lighting technologies known. Such bulbs are frequently used in projectors and other applications. A quartz bulb typically includes a spherical middle portion from which opposed first and second cylindrical portions extend in a co-axial manner. The spherical middle portion defines an interior chamber which contains mercury and/or halogen vapor or gas. Two electrodes within the chamber are typically made of tungsten or other high-melting point metal. First and second conductors extend from the electrodes through the opposed first and second cylindrical portions. In a typical application, the conductors are made of molybdenum, which is a conducing material that will bond to the quartz used to make the bulb. Such bonding is necessary to prevent leakage of the mercury and/or halogen vapor, particularly at high operating temperatures and pressures. 
   A failure mode for such bulbs involves degradation of the electrodes due to high start-up voltages. Accordingly, structures have been developed to reduce the start-up voltage required. In one design that reduces the required start-up voltage, one of the cylindrical portions may define a small bubble—within the quartz rod making up the cylindrical portion—which may be filled with mercury and/or halogen vapor. A coil surrounding the quartz rod and bubble is located on one side of the spherical middle portion, while the center of the reflector is located on the other side of the middle portion. The coil is typically held to ground or negative voltage while high voltage is applied to the electrodes. The coil acts in a manner similar to one plate of a capacitor, and tends to assist in the stimulation of the vapor in the bubble, thereby causing UV light to pass into the chamber. The UV light tends to reduce the start-up voltage required to create plasma from the mercury vapor. Upon creation of the plasma, the start-up voltage is stepped down to an operating voltage, and the pressure within the chamber defined within the spherical portion increases to approximately 200 atmospheres. 
     FIG. 9 , Prior Art, shows a cross-sectional view of an exemplary Prior Art lamp  900 . A high-pressure bulb  902  is centrally located within a reflector  904 . The bulb  902  includes a rearward cylindrical extension  906 , which is attached to the reflector  904 , typically by adhesive. A forward cylindrical extension  908  is wrapped with a coil  912 , which aids in starting the bulb  902 . A fireball portion  910  of the bulb  902  is located at approximately a focal point of the reflector  904 . A wire  916  provides power to one of the electrodes within the bulb  902 . Unfortunately, the coil  912  is sometimes damaged due to its exposed position on the cylindrical portion  908  of the bulb  902 . An additional problem is seen in that the coil  912  and wire  914  leading to the coil  912  tend to block light emitted from the spherical portion  910  of the bulb  902 . Accordingly, improved ultra high pressure lamps are needed. 
   SUMMARY 
   A lamp—suitable for use within a projector or other high-light output application—includes an ultra high pressure bulb. An extension from the bulb defines a start-up bubble. A conductor is carried by the extension of the ultra high pressure bulb, generally enclosing the start-up bubble, thereby exciting gas contained within the start-up bubble. A header defines a socket within which the extension and the conductor are carried. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following detailed description refers to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure (FIG.) in which the reference number first appears. Moreover, the same reference numbers are used throughout the drawings to reference like features and components. 
       FIG. 1  is shows an exploded view of an exemplary ultra high pressure bulb and conductor. 
       FIG. 2  is an assembled view of the exemplary ultra high pressure bulb and conductor of  FIG. 1 . 
       FIG. 3  is an isometric view of the ultra high pressure bulb and conductor of  FIG. 2  assembled within an exemplary header. 
       FIG. 4  is an isometric view similar to that of  FIG. 3 , additionally showing a layer of adhesive used to connect an extension of the ultra high pressure bulb, the conductor and the header. 
       FIG. 5  is an exemplary cross-sectional view of a lamp assembly, wherein the header and bulb assembly of  FIG. 4  is installed in a reflector. 
       FIG. 6  is an enlarged view of portions of the exemplary lamp of  FIG. 5 . 
       FIG. 7  is a flow diagram that describes an exemplary implementation, including a method employed for use in manufacturing an exemplary lamp assembly. 
       FIG. 8  is a flow diagram that describes an exemplary implementation, including a method employed for use in changing a failed lamp. 
       FIG. 9 , Prior Art, illustrates a typical prior art high-pressure bulb, showing how the coil is in an exposed location, and showing how the coil and wiring leading to the coil tend to block light emitted from the bulb. 
   

   DETAILED DESCRIPTION 
     FIG. 1  is shows an exploded view of an exemplary ultra high pressure bulb  100  and conductor  102 . The exemplary ultra high pressure bulb  100  is typically made of quartz, which resists the temperatures and pressures at which the lamp operates, and which is a poor conductor of electricity. The exemplary bulb  100  includes two cylindrical extensions  104 ,  106  which (as will be seen in greater detail in  FIG. 6 ) each contain conductors in electrical communication with an electrode within a fireball portion  108  of the lamp. 
   The exemplary conductor  102  is illustrated in the form of a coil; however, the conductor  102  could alternatively be configured as a plate, a screen grid or other electrically conductive formation. However, the coil configuration shown is easily manufactured to fit the extension of the bulb  100 . As will be seen in greater detail in  FIG. 6 , the operation of the conductor  102  allows the start-up voltage of the lamp to be reduced. 
     FIG. 2  is an assembled view of the exemplary ultra high pressure bulb  100  and conductor  102  of  FIG. 1 . Where the exemplary conductor  102  is configured as a coil, the conductor is easily installed on the extension  106  where the inside diameter of the coil is incrementally larger than the outside diameter of either extension. As seen in the example of  FIG. 2 , the conductor  102  is easily slid onto the extension  106  during assembly. 
     FIG. 3  is an isometric view of the ultra high pressure bulb  100  and conductor  102  of  FIG. 2  assembled within an exemplary header  300 . The exemplary header  300  of  FIG. 3  includes a generally cylindrical body  302  which defines an interior socket  304 . A closed end  306  of the cylindrical body  302  is attached to a base  308 . The exemplary base  308  includes at least two electrical contacts  310 . In the assembled state, one extension  106  of the bulb  100  is wrapped with the coil  102  and inserted into the socket  304 . 
     FIG. 4  is an isometric view of the header  300  that is similar to that of  FIG. 3 , additionally showing a layer of adhesive  400 . The layer of adhesive connects the extension  106  (better seen in  FIG. 1 ) of the ultra high pressure bulb  100 , the conductor  102  and the header  300 . 
     FIG. 5  is an exemplary cross-sectional view of a lamp assembly  500 , wherein the header and bulb assembly of  FIG. 4  is installed in a reflector  502 . The fireball  108  of the bulb is located generally at a focal point  504  of the reflector  502 . Wiring  506  may be used to power an electrode within the fireball  108  by attaching to a conductor within the cylindrical extension  106  of the bulb  100 . In the exemplary arrangement of  FIG. 5 , the base  308  of the header  300  is located generally at the center portion  508  of the reflector  502 , causing the bulb  100 , header  300  and reflector  502  to be co-axial. 
     FIG. 6  is an enlarged view of portions of the exemplary lamp of  FIG. 5 . The header  300  is located to position the header base  308  at a center portion  508  of the reflector  502 . An inside surface  608  of the cylindrical body  302  of the header  300  forms a socket  304  that encloses the cylindrical extension  106  of the bulb  100 , which is wrapped by the coil  102  and enclosed by the adhesive layer  400 . A molybdenum conductor  612  is defined within each cylindrical extension  104 ,  106  to power electrodes  602  contained within the fireball cavity  610  of the fireball  108  of the bulb  100 . 
   A start-up bubble  600  is defined within the extension  106  of the bulb  100 , and is located within a space generally surrounded by the coil  102 . The start-up bubble contains gas which is excited at start-up by the conductive coil  102 . The excitement of the gas within the start-up bubble results in the release of UV light, which excites gas within the fireball chamber  610 . Excitement of the gas within the fireball  108  lowers the voltage required at the electrodes  602 , which tends to extend electrode life. 
     FIG. 7  is a flow diagram that describes an exemplary implementation  700 , including a method employed for use in manufacturing an exemplary lamp assembly. At block  702 , a conductor  102  is installed within a socket  304  defined within a lamp header  300 . At block  704 , in an exemplary arrangement, the conductor coil  102  of  FIGS. 1 and 2  is used as the conductor. Note that while a coil is convenient, a wrapping of conductive foil or screen could be substituted. 
   At block  706 , the extension of an ultra high pressure bulb is installed into the socket  304  defined in the header  300 . 
   At block  708 , the extension  104  is oriented to locate the start-up bubble  600  within an area substantially enclosed by the conductor  102 . By orienting the start-up bubble with respect to the conductor  102 , the conductor will be able to excite the gas within the start-up bubble. 
   At block  710 , the fireball  108  is located at the focal point  504  of the reflector  502 . The fireball  108  may be located at the focal point of the reflector by appropriate selection of a header  300  and a lamp  100 , wherein the combined length of the selected header and lamp locate the fireball  108  at the focal point. Alternatively, the size of the reflector  502  selected can be altered, such that the fireball  108  is located at the focal point  504 . 
   At block  712 , the conductor and the extension are secured to the socket with a layer of adhesive. 
   ln some applications, blocks  702 - 712  may be performed simultaneously, thereby installing the coil, lamp extension and adhesive into the socket of the header at the same time. 
   At block  714 , the lamp header  300  is positioned within the reflector  502 . Note that, in contrast to conventional configurations, because the conductor  102  is located within the socket  304  of the header  300 , the conductor does not block light emitted from the fireball  108 . 
   At block  716 , the header  300  is secured to the reflector  502 . The lamp assembly is now operational. 
     FIG. 8  is a flow diagram that describes an exemplary implementation  800 , including a method employed for use in changing a failed lamp  100 . At block  802 , the failed bulb assembly, such as that seen in  FIG. 4 , is separated from the reflector  502 . At block  804 , a new bulb assembly is attached to the reflector  502 . At block  806 , the reflector is re-used. 
   Although the above disclosure has been described in language specific to structural features and/or methodological steps, it is to be understood that the appended claims are not limited to the specific features or steps described. Rather, the specific features and steps are exemplary forms of implementing this disclosure. For example, while actions described in blocks of the flow diagrams may be performed in parallel with actions described in other blocks, the actions may occur in an alternate order, or may be distributed in a manner which associates actions with more than one other block.