Patent Publication Number: US-6909248-B2

Title: Deuterium arc lamp assembly with an elapsed time indicator system and a method thereof

Description:
FIELD OF THE INVENTION 
   This invention relates generally to lamp assemblies and, more particularly, to a deuterium arc lamp assembly with an elapsed time indicator system and a method thereof. 
   BACKGROUND OF THE INVENTION 
   Basically, a deuterium lamp assembly has a cathode and an anode arranged within an evacuated glass envelope that contains deuterium gas. During operation, a stream of electrons flows from the cathode toward the anode exciting the gas within to produce light in the ultraviolet range. 
   The amount of time the deuterium lamp assembly is in operation may be monitored to provide an indication of the remaining life span of the deuterium lamp assembly. To monitor the amount of usage, existing deuterium lamp assemblies have used either mercury or copper coulombmeters. Unfortunately, there are obvious environmental issues with the use of mercury coulombmeters and copper coulombmeters are sensitive to orientation which can effect their proper operation. 
   SUMMARY OF THE INVENTION 
   A lamp system in accordance with one embodiment of the present invention includes a light source and an elapsed time indicator system which is coupled to the light source. The elapsed time indicator system accumulates a count of elapsed time of operation of the lamp system. The count provides an indication of a life span of the lamp system. 
   An elapsed time indicator system for a lamp assembly in accordance with another embodiment of the present invention includes a sensing system and a counter. The sensing system senses when the lamp assembly is in operation and the counter accumulates and provides a count of elapsed time of operation of the lamp assembly. The counter advances the count when the sensing system senses that the lamp assembly is in operation. The count provides an indication of a life span of the lamp system. 
   A method for monitoring usage of a lamp system in accordance with another embodiment of the present invention includes sensing when the lamp system is in operation and advancing a count when the sensing indicates the lamp system is in operation. The count provides an indication of a life span of the lamp system. 
   The present invention provides an effective system and method for monitoring usage of a lamp assembly. Additionally, the present invention eliminates the need of mercury contained in existing timers and eliminates the orientation limitations inherent with existing copper timers. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  is a partial schematic and partial block diagram of a lamp assembly with an elapsed time indicator system in accordance with an embodiment of the present invention; and 
       FIG. 2  is a block diagram on the elapsed time indicator system. 
   

   DETAILED DESCRIPTION 
   A lamp system or assembly  10  with an elapsed time indicator system  12  in accordance with an embodiment of the present invention is illustrated in  FIGS. 1 and 2 . The lamp system  10 , such as a deuterium arc lamp system, includes at least one power supply  32 , a light source or lamp  16 , and an elapsed time indicator system  12  with a sensing system  18 , a counter  20 , and a display  22 . The present invention provides an effective and accurate system  10  and method for monitoring usage of a light source  16 . 
   Referring to  FIG. 1 , the light source  16  includes an anode  24  and a cathode filament  26  arranged in a spaced apart relationship within an evacuated glass envelope  28  which is subsequently filled with deuterium gas, although other types of light sources with other components and in other gases or a vacuum can be used. 
   In this particular embodiment, the light source  16  also includes a filament power supply  30  which is coupled to the cathode filament  26 . The filament power supply  30  applies a starting voltage to heat-up the cathode filament  26 , also known as a thermal electron emitter, to a point where electrons will be emitted from the cathode filament  26 . The amount of the starting voltage which is applied depends on the type of light source  16  being used. Once the light source  16  starts, the voltage provided by the filament power supply  30  is reduced or switched off. The amount of voltage applied by the filament power supply varies depending on the type of light source  16  being used. 
   The lamp power supply  32  is coupled via leads to the anode  24  and the cathode filament  26  in the envelope  28 . The lamp power supply  32  includes a switch which controls when current is supplied to the light source  16 . In this particular embodiment, the lamp power supply  32  is a constant-current source, regulated at about 300 mADC current operating at a starting voltage range of about 250 VDC to about 750 VDC and an operating voltage range between about 60 VDC to about 90 VDC, although other types of lamp power supplies operating at other currents and voltages can be used. 
   Referring to  FIGS. 1 and 2 , the elapsed time indicator system  12  accumulates and displays the amount of time that the light source  16  has been operating. In this particular embodiment, the elapsed time indicator system  12  is shown separate from the light source  16 , although elapsed time indicator system  12  may be incorporated into one package with the light source  16 . The elapsed time indicator system  12  includes a sensing system  18 , a counter  20 , a display  22  or graphical user interface, a central processing unit (CPU) or processor  34 , a memory  36 , a user input device  38 , and a backup power supply  40  which are coupled together by a bus system  42  or other link, respectively, although the elapsed time indicator system  12  may comprise other components, other numbers of the components, and other combinations of the components. 
   The sensing system  18  senses when current is flowing in the lamp system  10  and signals the counter  20  to advance the count of elapsed time of operation when the current is flowing, although the sensing system  18  could signal to advance the count in the counter based on sensing other characteristics which indicate that the light source is in operation, such as sensing the application of a pulsed current or the application of a voltage to the light source  16 . The sensing system  18  signals the counter  20  to stop the count of elapsed time of operation when the flow of current is no longer sensed, although the sensing system  18  could stop the count in the counter  20  based on sensing other characteristics which indicate that the light source  16  is no longer in operation, such as sensing that a pulsed current has stopped or that a voltage is no longer being applied to the light source  16 . A variety of different types of sensing systems which sense one or more characteristics can be used for sensing system  18 , such as a sensing system that senses a constant current, a pulsed current, or a voltage. 
   The counter  20  is activated when the sensing system  18  senses a current or other characteristics applied to the light source  16  and upon activation begins or continues to accumulate a total time of operation of the light source  16 . In this particular embodiment, the counter  20  is a microcontroller, although other types of sensing systems can be used. 
   The display  22  is used to show the count and may also be used to provide an expiration signal when the count reaches a set number which can vary based on the lamp system and can be input or altered by the operator. A variety of different of devices can be used for the graphical user interface or display  22 , such as a CRT, LCD, or LED. In this particular embodiment, the display may show a reading up to 9999 or more hours, although this can vary, e.g. the display may be able to show a reading up to 99999. Most lamp systems or assemblies have an operating life of about 1000 to 2000 hours, although this can also vary based on the particular type of lamp system or assembly. Once the count reaches a milestone, such as 2000 hours for a lamp system or assembly with an expected life span of 2000 hours, then the system  12  may cause a unique readout to appear on the display, such as - - - - or 8888, although the type of unique readout can also vary. The system  10  can also provide some other type of notification that the life span of the lamp system is at or near its end. Although in this particular embodiment, the counter  20  and display  22  are shown as separate elements, the counter  20  and display  22  could be integrated as one device. 
   The processor  34  may execute one or more programs of stored instructions for the method for monitoring usage of a light source  16  as described herein. In this particular embodiment, these programmed instructions are stored in memory  36 , although some or all of those programmed instructions could be stored and retrieved from and also executed at other locations. The memory  36  also stores information, such as accumulated operation time when the light source  16  is not in operation. A variety of different types of memory storage devices, such as a random access memory (RAM) or a read only memory (ROM) in the system or a floppy disk, hard disk, CD ROM, or other computer readable medium which is read from and/or written to by a magnetic, optical, or other reading and/or writing system that is coupled to the processor  40 , can be used for memory  36 . 
   The user input device  38  permits an operator to communicate with the elapsed time indicator system  12 , such as a button which can be pressed to illuminate the display  22  to show the accumulated count. A variety of different types devices can be used for elapsed time indicator system  12 , such as a button, buttons, keyboard, or a computer mouse. 
   The backup power supply  40  provides power to the elapsed time indicator system  12 . With the backup power supply  40 , functions of the elapsed time indicator system  12  can be accessed even when the lamp power supply  32  is off or disconnected from the light source  16 , such as power to store the accumulated count in memory  36  or to illuminate or show the accumulated count on the display  22  when a user input device  38 , such as a button, is activated. 
   The operation of the lamp system  10  will be described with reference to  FIGS. 1 and 2 . The filament power supply  30  is engaged to provide a starting voltage to the cathode filament  26 . The starting voltage heats up the cathode filament  26  to a point where electrons are emitted from the cathode filament  26 . The amount of the starting voltage which is applied depends on the type of light source  16  being used. Once the light source  16  starts to emit light, the voltage provided by the filament power supply  30  is reduced or switched off. 
   Meanwhile, the lamp power supply  32  is engaged and supplies a current, such as a constant current or repetitive pulses of current, to the light source  16 . This current causes a stream of thermoelectrons to flow from the cathode filament  26  toward the anode  24  within the envelope  28  to produce light in the ultraviolet range. 
   When the lamp power supply  32  begins to supply a current to the light source  16 , the sensing system  18  senses this flow of constant current, repetitive pulses of current, or some other characteristic that indicates the lamp system  10  is in operation and signals the counter  20  to begin counting, although the sensing system  18  can be set up to sense other characteristics indicating the operation of the light source  16 , such as the application of a voltage to the light source  16 . The counter  20  continues to count to accumulate total time of lamp operation until the sensing system  18  senses that the flow of current, repetitive pulses of current, or some other characteristic has stopped and then signals the counter  20  to stop counting. 
   The accumulated count on the counter  20  may be shown on the display  22  and/or may be stored in memory  36 . When the count in the counter  20  exceeds the stored count for the life expectancy of that light source  16 , then the counter  20  displays a signal indicating that the light source  16  should be replaced. By way of example, the typical life expectancy for Many deuterium light sources is about 1000 hours or 2000 hours, depending on the particular light source. When the count in the counter  20  reaches 1000 hours or 2000 hours, the display  22  may show 8888 or some other designation not in sequence with the count to signal that the light source needs to be replaced. 
   If the lamp power supply  32  is turned off or disconnected, the backup power supply  40  continues to provide power to components of the elapsed time indicator system  12 , such as the display  22 . As a result, by activating a user input device  38 , such as a pressing a button, the accumulated count for the light source  16  can be shown on the display  22 . 
   The present invention provides an effective and accurate system and method for monitoring usage of a lamp assembly. As a result, after extended use an operator of a lamp system  10  knows when it is time to replace the light source  16  before the light source  16  actually expires. 
   Having thus described the basic concept of the invention, it will be rather apparent to those skilled in the art that the foregoing detailed disclosure is intended to be presented by way of example only, and is not limiting. Various alterations, improvements, and modifications will occur and are intended to those skilled in the art, though not expressly stated herein. These alterations, improvements, and modifications are intended to be suggested hereby, and are within the spirit and scope of the invention. Additionally, the recited order of processing elements or sequences, or the use of numbers, letters, or other designations therefor, is not intended to limit the claimed processes to any order except as may be specified in the claims. Accordingly, the invention is limited only by the following claims and equivalents thereto.