Patent Publication Number: US-2004046511-A1

Title: Controller and method for creating added functionality from a fluorescent lamp and light fixture

Description:
[0001] This invention relates to fluorescent lamps and light fixtures for fluorescent lamps. More particularly, this invention relates to the new and improved combination of a starter and sensor with a fluorescent lamp, or with a light fixture having a fluorescent lamp, to create added functionality from the fluorescent lamp or the light fixture. The added functionality involves controlling the light emitted from the fluorescent lamp in response to external influences, such as ambient light, motion, automatic timing, and other things. The added functionality is conveniently achieved by replacing the fluorescent lamp or by replacing a starter for the fluorescent lamp within the light fixture, making it unnecessary to replace the entire light fixture or to wire an existing light fixture with additional components.  
       BACKGROUND OF THE INVENTION  
       [0002] Incandescent lamps are frequently used with external devices as ambient light-responsive switches, motion detectors, automatic timers, and the like. In such cases the incandescent lamp is typically screwed into an adapter, and the adapter is screwed into the socket where the incandescent lamp is otherwise usually attached. The added functionality of lighting and extinguishing the incandescent lamp is contained in the adapter. In other cases, the added functionality to control the incandescent lamp is connected in a separate control device which is electrically connected to a conventional electrical power wall socket, and an electrical cord from the light is connected to the separate control device. One example is an ambient light responsive function, where the incandescent lamp is energized upon the detection of a low ambient light condition and de-energized when the ambient light returns to a normal level. Another example is a motion responsive detection function, where the incandescent lamp is energized upon detecting motion within a certain space and remains energized for a predetermined time after the motion ceases within that space. Still another example is an automatic timing responsive function, where the incandescent lamp is energized at a predetermined time and is de-energized at a later predetermined time.  
       [0003] These types of adapters and control devices are widely available, and a consumer is capable of connecting such adapters and control devices in a safe manner. The adapters and the control devices are also relatively safely and simply incorporated in adapters and control devices, because of the relatively non-complex manner in which an incandescent lamp may be energized by simply switching conventional alternating current (AC) current through the incandescent lamp to light it, and then opening the switch to terminate the AC current flow through the incandescent lamp to extinguish it.  
       [0004] If the consumer wishes to add additional functionality to a conventional fluorescent lamp light fixture, such as to make it responsive to ambient light, motion or automatic timing, the typical consumer must hire a skilled electrician to connect the desired control device to the fixture so that the control device causes the light source in the fixture to energize and de-energize according to the type of responsiveness desired. Alternatively, the entire light fixture must be replaced with a new light fixture that includes the added functionality. In some countries it is illegal for anyone other than a licensed or regulated electrician to wire new light fixtures or make modifications to existing light fixtures. The cost of the services of a skilled electrician is a deterrent to consumers seeking added functionality of their light fixtures.  
       [0005] The complexity of the functions required to ignite and extinguish a fluorescent lamp have also contributed to the inability to add new functionality to fluorescent lamps or the light fixtures in which fluorescent lamps are used. A starter and the ballast are required to ignite the typical fluorescent lamp, and the starter must create certain electrical conditions to ignite the fluorescent lamp. Simply applying conventional AC power to a fluorescent lamp will not result in lighting that lamp, as is the case with an incandescent lamp. Moreover, extinguishing a lighted fluorescent lamp is usually achieved by manually switching off the conventional AC power to the fluorescent lamp. The added functionality of the starter, coupled with the typical inability to extinguish the fluorescent lamp under appropriate conditions, have combined to substantially limit or prevent external influence-responsive control devices from being used with fluorescent lamps. In those cases where control devices have been used with fluorescent lamps, the services of a skilled electrician are typically required to connect the control devices in the lighting circuit involving the fluorescent lamp light fixture or the conventional fluorescent lamp lighting circuit had to be modified.  
       SUMMARY OF THE INVENTION  
       [0006] This invention creates additional functionality from a fluorescent lamp or fluorescent lamp light fixture by enabling responsiveness to external influences, such as turning on and off automatically in response to ambient light, to detected motion, and to the occurrence of predetermined times, while still permitting normal lighting functionality when desired. The functionality is added to the fluorescent lamp itself, or to a separate starter associated with a light fixture, thereby permitting the consumer to replace the fluorescent lamp or the starter in the fluorescent lamp light fixture to obtain, safely and lawfully, the benefits of this additional functionality. By incorporating the added functionality in the fluorescent lamp or in a starter associated with a fluorescent lamp light fixture, no rewiring or replacement of the light fixture is required. The relatively low additional cost to incorporate the additional functionality in the fluorescent lamp or in a starter associated with a fluorescent lamp light fixture makes it attractive to a consumer to obtain the additional functionality.  
       [0007] One aspect of the invention relates to a controller for igniting and extinguishing a fluorescent lamp in response to an external influence. The fluorescent lamp is part of the fluorescent lighting circuit which also includes a magnetic ballast connected in series with the fluorescent lamp and an alternating current (AC) power source. The fluorescent lamp includes filaments and has a characteristic lamp ignition voltage at which an electrically conductive plasma exists between the filaments. The controller comprises a sensor which responds to the external influence and supplies a control signal related to the presence or absence of the external influence. A starter responds to the control signal to ignite and extinguish the fluorescent lamp. To ignite the fluorescent lamp, the starter conducts current through the filaments to heat them and to create a change in current per change in time (di/dt) to induce a high-voltage pulse from the magnetic ballast sufficient to ignite the plasma between the filaments at a time when the voltage from the AC power source is greater than the lamp ignition voltage. The starter also conducts current through the filaments without generating a high-voltage starting pulse to extinguish the plasma. The controller is physically connected to one of either the fluorescent lamp or within a starter socket intended to receive a conventional starter in the fluorescent lamp lighting circuit.  
       [0008] Other significant aspects of the invention related to the controller involve physically connecting the controller either to the exterior of the base of a fluorescent lamp or within the interior of the base of the fluorescent lamp. Alternatively, the controller can be located in a remotely positioned housing and electrically connected with a conductor and interactive electrical connectors to the base of the fluorescent lamp. As another alternative, the controller can be located within a housing that is adapted to electrically and mechanically connect to a conventional starter socket of the fluorescent lamp light fixture. As a further alternative, the housing for the controller may be remotely located and connected with an adapter and an electrical conductor into the conventional starter socket of the light fixture. In all these situations, the sensor has a field of responsiveness within which to respond to the exterior influence. A structure is attached to the base or to the housing and positioned relative to the sensor to define and limit the field of responsiveness. The sensor may comprise a motion detector, an ambient light detector or a timer, for example, in order to respond to the exterior influences of ambient light, motion or the passage of time.  
       [0009] Another aspect of the present invention relates to a method of igniting and extinguishing a fluorescent lamp in response to an external influence. The method involves connecting the fluorescent lamp in a fluorescent lamp lighting circuit which includes a magnetic ballast connected in series with an alternating current (AC) power source, sensing the presence and absence of the external influence, igniting the fluorescent lamp and extinguishing the fluorescent lamp in response to the presence and absence of the external influence, and sensing the external influence at a location on the fluorescent lamp or at a location within a starter socket intended to receive a conventional starter in the fluorescent lamp lighting circuit. The fluorescent lamp is ignited by conducting current through filaments of the lamp to heat them and by creating a di/dt through the magnetic ballast to induce a high-voltage pulse from the magnetic ballast sufficient to ignite the plasma. The fluorescent lamp is extinguished by conducting current through the filaments and without creating a di/dt sufficient to induce the high-voltage pulse.  
       [0010] Other significant aspects of the invention related to the method of igniting and extinguishing the fluorescent lamp include establishing a field of responsiveness location within which to respond to the exterior influence, and defining and limiting the field of responsiveness at the sensing location. Ambient light, motion or time may be sensed as the basis for igniting and extinguishing the fluorescent lamp.  
       [0011] A more complete appreciation of the scope of the present invention and the manner in which it achieves the above-noted and other improvements can be obtained by reference to the following detailed description of presently preferred embodiments taken in connection with the accompanying drawings, which are briefly summarized below, and by reference to the appended claims. 
     
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
     [0012]FIG. 1 is a perspective view of a conventional fluorescent lamp, shown in a partially exploded and broken away form.  
     [0013]FIG. 2 is an exploded perspective view of a conventional fluorescent lamp light fixture, including a starter and the fluorescent lamp shown in FIG. 1.  
     [0014]FIG. 3 is an enlarged perspective view of one type of a prior art starter which may be used in the light fixture shown in FIG. 2.  
     [0015]FIG. 4 is an enlarged perspective view of another type of prior art starter which may be used in the light fixture shown in FIG. 2.  
     [0016]FIG. 5 is a perspective view of another conventional fluorescent lamp having a self-contained starter, shown in a partially exploded and broken away form.  
     [0017]FIG. 6 is a schematic circuit diagram of a prior art fluorescent lamp circuit, which illustrates the role of a starter in igniting and extinguishing the fluorescent lamp.  
     [0018]FIG. 7 shows superimposed voltage and current waveform diagrams illustrating the functionality of the starter shown in FIGS.  2 - 6 , in controlling the light emission from the fluorescent lamp shown in FIGS. 1, 2,  5  and  6 .  
     [0019]FIG. 8 is a generalized schematic circuit and block diagram of a starter and sensor which cooperatively function as an external influence responsive, fluorescent lamp controller in accordance with the present invention.  
     [0020]FIG. 9 is a perspective view of a fluorescent lamp similar to FIG. 1, but having the controller shown in FIG. 8 attached to a base of the fluorescent lamp, in accordance with the present invention.  
     [0021]FIG. 10 is a perspective view of a fluorescent lamp similar to FIG. 5, but having the controller shown in FIG. 8 incorporated within a base of the fluorescent lamp, in accordance with the present invention.  
     [0022]FIG. 11 is a perspective of a fluorescent lamp similar to FIG. 1 or  5 , but having the controller shown in FIG. 8 remotely positioned and electrically connected to a base of the fluorescent lamp by a conductor and an electrical connector, in accordance with the present invention.  
     [0023]FIG. 12 is an exploded perspective view of a light fixture similar to FIG. 2, but having an adapter electrically connected to a remotely connected controller shown in FIG. 8, in accordance with the present invention, with the adapter and the controller shown enlarged relative to the light fixture.  
     [0024]FIG. 13 is an exploded perspective view of a light fixture similar to FIG. 2, but having the controller shown in FIG. 8 used in replacement for a prior art starter, in accordance with the present invention, with the controller shown enlarged relative to the light fixture. 
    
    
     DETAILED DESCRIPTION  
     [0025] The present invention applies to conventional fluorescent lamps  20  and  21 , respectively exemplified in FIGS. 1 and 5, and to conventional fluorescent lamp starters  22  and  23  respectively exemplified in FIGS. 3 and 4, which are used in a conventional fluorescent lamp light fixture  26  exemplified in FIG. 2. The connection of one fluorescent lamp and one starter is illustrated in a conventional fluorescent lamp lighting circuit  28 , shown in FIG. 6. The starter ignites and extinguishes the fluorescent lamp, in the manner illustrated by exemplary voltage and current waveforms shown in FIG. 7. A fluorescent lamp controller  29  which incorporates a starter is shown in FIG. 8, and this controller  29  is the electrical basis for exemplary embodiments of the present invention shown in FIGS.  9 - 13 .  
     [0026] The conventional fluorescent lamp  20 , shown in FIG. 1, comprises at least one fluorescent lamp tube  30 , which in the case of the fluorescent lamp  20  is bent in a single U-shaped configuration. The fluorescent lamp tube  30  is typically formed as a closed and evacuated translucent housing or glass tube which has been coated on the inside with a conventional phosphorescent material which emits light when energized. A small amount of mercury is contained within the closed tube  30 . As shown in FIG. 6, filaments  32  and  34  are located within the tube  30  and at opposite ends of the tube. Conductors  36  and  38  extend through the tube  30  and connect to opposite ends of the filament  32 , and conductors  40  and  42  extend through the tube  30  and connect to opposite ends of the filament  34 . Electrical voltage and current is applied to the filaments  32  and  34  through the conductors  36 ,  38  and  40 ,  42 , respectively, to ignite and maintain a plasma between the filaments  32  and  34 . The plasma energizes the phosphorescent coating within the tube  30  to emit light. Quenching or extinguishing the electrical plasma ceases light emission from the tube  30 . A starter interacts with the other elements of the fluorescent lighting circuit  28  (FIG. 6) to create the electrical conditions at the filaments  32  and  34  which ignite and extinguish the fluorescent lamp.  
     [0027] The tube  30  is connected to a base  44  of the fluorescent lamp  20 , to thereby retain the tube  30  at a fixed position as a part of the fluorescent lamp  20 , as shown in FIG. 1. The conductors  36 ,  38 ,  40  and  42  are electrically connected within the base  44  to connection pins  46 ,  48 ,  50  and  52 , respectively, which extend from the base  44 . The connection the pins  46 - 52  fit within receptacles (not shown) of a lamp socket  54  in the light fixture  26  (FIG. 2) to electrically connect the fluorescent lamp  20  to the light fixture  26  and within the fluorescent lighting circuit  28  (FIG. 6).  
     [0028] The fluorescent lamp  20  does not include a self-contained starter. Consequently it is necessary to use an external starter  22  or  23  (FIG. 3 or  4 ) with the fluorescent lamp  20  in order to ignite the plasma within the tube  30 . The typical external starter  22  or  23  is connected in a starter socket  56  of the light fixture  26 , as shown in FIG. 2. Connected in this manner, the external starter  22  or  23  is replaceable. The user simply disconnects the external starter  22  or  23  from the socket  56  and connects a new starter in the socket  56 . In this case, the socket  56  is electrically connected to the starter shown in the lighting circuit  28  (FIG. 6). Upon insertion of an external starter  22  or  23  in the socket  56 , the circuit diagram for the lighting circuit  28  appears as shown in FIG. 6.  
     [0029] The two general types of external starters  22  and  23  for fluorescent lamps are conventional and shown in FIGS. 3 and 4. The starter  22  shown in FIG. 3 is a typical two pin “glow bottle” starter. Two electrical pins  58  and  60  extend from a housing  62 . The two pins  58  and  60  connected to electrical contacts (not shown) within the starter socket  56  (FIG. 2). The starter  23  shown in FIG. 4 is a typical screw-in “glow bottle” starter. Two electrical contacts are created by threaded end connector  64  connected to a housing  66 . The threaded end connector  64  includes a center contact button  68  which is electrically insulated from an outside threaded sleeve  70 . The contact button  68  and the threaded sleeve  70  form the two electrical contacts. The threaded sleeve  70  is screwed into a corresponding threaded receptacle (not shown) of the starter socket  56  (FIG. 2). Connecting the two electrical pins  58  and  60  of the starter  22  (FIG. 3) into the starter socket  56  (FIG. 2), or connecting the threaded end connector  64  of the starter  23  (FIG. 4) into the starter socket  56  (FIG. 2), connects one of the starters  22  or  23  in the lighting circuit  28 , in the manner shown in FIG. 6.  
     [0030] The fluorescent lamp  21 , shown in FIG. 5, includes its own internal starter  24  located in a starter receptacle  74  which is formed as part of a base  76  of the lamp  21 . The internal starter  24  is also of the conventional “glow bottle” type, and includes a housing  78 . Because the fluorescent lamp  21  utilizes its own internal starter  24 , it is not necessary to provide an external starter for the fluorescent lamp  21 . Instead, the internal starter  24  is electrically connected to two of the conductors  36  and  40  from the tube  30  of the lamp  21 , thereby achieving the same electrical connection of the starter as shown in the fluorescent lighting circuit  28  (FIG. 6). Because the starter  24  is internally connected to the conductors  36  and  40 , only two connection pins  48  and  52  are necessary in the lamp  21  for its connection in the lighting circuit  28  (FIG. 6). The internal starter  24  is usually permanently affixed within the starter receptacle  74 , so that replacement of the internal starter  24  is not possible. The entire fluorescent lamp  21  must be replaced if either the fluorescent tube  30  or the internal starter  24  fails.  
     [0031] The fluorescent lamp  21  also exemplifies the situation where the tube  30  is bent into multiple U-shaped configurations, thereby achieving a longer fluorescent tube which emits more light than a shorter fluorescent tube  30  which is bent in only a single U-shaped configuration as shown in FIG. 1. The present invention is also applicable to fluorescent lamps which are formed in the shape of an elongated, straight cylindrical tube with electrical contacts at opposite ends.  
     [0032] The role of a conventional starter  22 ,  23  or  24  in igniting fluorescent lamp  20  or  21  can be understood by reference to the fluorescent lighting circuit  28  shown in FIG. 6, where the conventional starter is designated  80 , and the fluorescent lamp is designated  82 . The fluorescent lamp  82  is connected in series with a current limiting inductor known as a ballast  84 . Conventional alternating current (AC) power from a source  86  is conducted through a conventional on-off light control switch  88  to the series connected lamp  82  and the ballast  84 . The filaments  32  and  34  are connected by the conductors  38  and  42  and connection pins  48  and  52  to the ballast  84  and the AC source  86 . The filaments  32  and  34  are connected by the conductors  36  and  40  (and connection pins  46  and  50 , if used).  
     [0033] To initiate ignition of the lamp  82 , the starter  80  first heats the filaments  32  and  34 . The starter  80  establishes a current path between the conductors  36  and  40 , thereby connecting both filaments  32  and  34  in a series current flow path with the AC source  86 , which causes current to flow through both the filaments  32  and  34  from the AC source  86  for a period of time sufficient to heat filaments  32  and  34 . The heat from the filaments helps vaporize the mercury within the tube  30 . The heated filaments  32  and  34  also emit low work energy ions from material coated on the surface of the filaments. The emitted ions create an ionized cloud surrounding the filaments  32  and  34 . This ionized cloud assists in establishing a break-over arc between the filaments  32  and  34  to ignite the lamp  82  and to maintain the lamp in a lighted condition.  
     [0034] After heating the filaments  32  and  34 , the starter  80  opens the current path through the filaments  32  and  34 . The current flow through the ballast  84  terminates almost instantaneously, causing a relatively high change in current in a relatively short amount of time (di/dt). The ballast  84  responds to the relatively high di/dt by producing a very high voltage pulse  90  shown in FIG. 7. The pulse  90  is of sufficiently high voltage to break down the ionized electron cloud and the mercury vapor within the tube  30 , thereby conducting an arc between the filaments  32  and  34  caused by the high voltage pulse  90 . The arc jumps directly between the filaments  32  and  34  because the starter  80  has opened and no longer presents a current path between the filaments. The arc creates the plasma within the tube  30 , and the plasma emits ultraviolet light which interacts with phosphorus on the interior of the tube  30  to cause the phosphorus to emit visible light and ignite the lamp  82 . The current flow through the plasma between the filaments  32  and  34  thereafter heats the filaments  32  and  34 . The filaments are sufficiently heated to maintain enough ionization to allow the normal AC voltage  92  from the source  86  to ignite the plasma thereafter during the subsequent half cycles of applied AC voltage  92 , shown in FIG. 7, without the need for further high voltage starting pulses  90 .  
     [0035] The typical voltage characteristics applicable to the fluorescent lamp  82  are shown in FIG. 7. The applied voltage from the conventional AC source  86  (FIG. 6) is shown at  92 . Under operating conditions, the voltage across the filaments  32  and  34  builds up until an ignition or break-over voltage  94  is reached. The ignition voltage may vary somewhat depending on the heat of the cathodes and the extent of vaporization, but it is necessary to apply a voltage between the filaments  32  and  34  (FIG. 6) which is at least equal to the break-over voltage  94  to sustain the plasma state. The voltage  94  remains approximately constant after steady state conditions are attained in the lamp  82 . Because the peak voltage of the of the applied voltage  92  is greater than the ignition voltage  94 , the arc current between the filaments  32  and  34  through the plasma will increase to an unacceptable level unless the ballast  84  is employed. The ballast  84  limits the current under normal operating conditions.  
     [0036] The typical type of starter  80  is a “glow bottle” starter  22 ,  23  or  24  shown in FIGS. 3, 4 or  5 , respectively. The glow bottle starters  22 ,  23  or  24  have an evacuated housing  62 ,  66  or  78 , respectively, within which there are confined a radioisotopic ionizable gas and a bimetal switch (neither shown). The voltage applied to the glow bottle starter causes current to flow through the radioisotopic gas, thereby heating the gas. The voltage at which the radioisotopic gas ionizes and begins to conduct current is above the level of the lamp ignition voltage  94  shown in FIG. 7. When the fluorescent lamp  82  is not lighted the full voltage of the AC source  86  is impressed across the radioisotopic gas. When the normally open bimetal switch becomes hot enough, it closes and shunts the current flow through the closed switch rather than the radioisotopic gas in the glow bottle. The closed bimetal switch conducts current through the filaments  32  and  34  to heat them. The radioisotopic gas starts cooling when the bimetal switch closes, because the gas is no longer heated by current flow through the gas. The bimetal switch also begins cooling when the gas is no longer heated.  
     [0037] When the bimetal switch has cooled sufficiently, it opens and causes a high di/dt. The ballast  84  responds to the di/dt by generating and applying the high voltage pulse  90  to the warmed filaments  32  and  34 . The lamp  82  will only be lighted if the bimetal switch opens at a time when the AC voltage  92  across the filaments  32  and  34  is above the ignition voltage  94 . Once the high voltage pulse  90  initiates the arc between the filaments  32  and  34 , the AC voltage  92  will sustain that arc provided that it is greater than the ignition voltage  94 . Once the arc is initiated and the voltage between the filaments  32  and  34  is that of the ignition voltage  94 , the voltage across the radioisotopic gas in the glow bottle never reaches a high enough value to cause the radioisotopic gas to conduct current and heat the bimetallic switch because the ignition voltage  94  is lower than the ionization voltage of the radioisotopic gas. After the lamp  82  is extinguished by opening the control switch  88 , the glow bottle will again become operative upon closing the control switch  88  (FIG. 6).  
     [0038] A conventional glow bottle starter will eventually fail from continued use. The bimetallic switch ceases to function adequately, or the radioisotopic gas loses its ability to ionize and heat up. Disposing of the worn out glow bottle starter with its radioisotopic gas presents an environmental concern. Because of these and other issues associated with glow bottle starters, electronic fluorescent lamp starters have been developed for use with conventional magnetic ballasts. Examples of electronic starters developed by the assignee of the present invention, and uses of such starters, are described in U.S. Pat. Nos. 5,504,398; 5,537,010; 5,757,145; 5,955,847; 5,708,330; 5,736,817; 5,739,640; 5,631,523; and 5,652,481. A simplified form of one such electronic starter  100  is shown in FIG. 8.  
     [0039] The starter  100  shown in FIG. 8 is connected to the conductors  36  and  40  or pins  46  and  50 , which extend from the fluorescent lamp  82  (FIG. 6). In this regard the starter  100  is a direct replacement for the starter  80 . The starter  100  utilizes a high holding current thyristor such as an SCR, a triac or other type of semiconductor current switching device, exemplified by a triac  102  (FIG. 8). The holding current of the triac  102  refers to the minimum amount of current that it will conduct between its current conduction terminals connected to the conductors  36  and  40  and pins  46  and  50 , before ceasing to conduct because of its internal semiconductor characteristics. The high holding current characteristic of the triac  102  is advantageously used in the starter  100  to create the high voltage starting pulse  90  (FIG. 7) to ignite the fluorescent lamp  82  (FIG. 6).  
     [0040] The conductivity of the triac  102  is controlled by a micro controller  106 . The micro controller  106  delivers the trigger signal  104  to the triac under predetermined conditions to cause the fluorescent lamp  82  (FIG. 6) to ignite and extinguish. The trigger signal  104  is delivered by the micro controller  106  relative to the voltage from the AC source  86  (FIG. 6) which is impressed across the filaments  32  and  34  and sensed by the connection of the micro controller  106  to the conductors  36  and  40 .  
     [0041] To ignite the fluorescent lamp, the micro controller  106  applies the trigger signal  104  to the triac  102 . The triac  102  conducts current through the filaments  32  and  34  (FIG. 6) and heats them. The triac  102  may be triggered in this manner for a series of sequential half cycles of the applied AC current  96  shown in FIG. 7, by applying and maintaining the trigger signal  104  for the entire duration of each of a predetermined number of half cycles of applied AC current during the filament warm-up period. After the filaments have been heated sufficiently, the trigger signal  104  is terminated while current flows through the triac  102  during the half cycle of applied AC current of the filament warm-up period. As the current from the applied half cycle of AC power diminishes to the holding current level of the triac  102 , shown at  97  in FIG. 7, the triac immediately commutates to a nonconductive state to create the high di/dt from the ballast  84 , (FIG. 6). The commutation of the triac to the non-conductive state is shown at  98  in FIG. 7. Because the relatively high holding current characteristic of the triac  102 , a considerably higher di/dt is created than would exist with a conventional semiconductor switch device which has a lower holding current characteristic. This relatively high di/dt causes the ballast  84 , (FIG. 6) to generate the high voltage pulse  90 , thereby igniting the lamp.  
     [0042] Because the inherent characteristics of the ballast  84  cause a phase shift of the current by about 90 degrees in time relative to the voltage, the high voltage pulse  90  occurs when the impressed voltage  92  across the filaments  32  and  34  is near its peak value and above the ignition voltage level  94 . This timing maximizes the opportunity to ignite the mercury plasma in the fluorescent lamp. After ignition, the plasma is sustained by the applied AC voltage for the duration of that half cycle. Subsequent half cycles of applied AC voltage  92  directly ignite the plasma in the lamp tube for the reasons previously described. If the lamp is not immediately ignited by the first high voltage pulse  90 , the micro controller  106  will sense that the lamp has not ignited and will again perform the starting sequence until the lamp lights.  
     [0043] To extinguish the lamp, the micro controller  106  applies the trigger signal  104  to the triac  102  continuously for an entire half cycle. The triggered triac  102  connects the filaments  32  and  34  and prevents current flow through the gas between them. The plasma in the lamp  82  is immediately extinguished. As the current flowing through the filaments  32  and  34  decreases to the holding level of the triac  102  at the end of the half cycle of applied AC current, the trigger signal  104  is continually applied to prevent the triac  102  from commutating into a nonconductive state as the current passes through the holding current level. This inhibits the generation of the di/dt effect, which prevents the generation of a starting pulse. Without a starting pulse, the lamp remains extinguished. The filaments  32  and  34  cool sufficiently to no longer ignite the plasma just from the applied AC voltage. Thereafter, the micro controller  106  no longer delivers trigger signals  104  to the triac  102 . The fluorescent lamp is thus quickly extinguished within one cycle of applied AC power.  
     [0044] The fluorescent starter  100  is effective in lighting the fluorescent lamp by creating a high di/dt at the time when the voltage across the cathodes nears its peak, thereby enhancing ignition of the lamp. Reliable ignition of the lamp is achieved on a very rapid basis. Moreover, the ability to control the triac  102  for the purpose of extinguishing the plasma and to prevent the generation of the high voltage starting pulses allows the starter  100  to quickly extinguish the lighted fluorescent lamp.  
     [0045] The fluorescent lamp controller  29  of the present invention uses the starter  100  and a connected sensor  110 , as shown in FIG. 8. The sensor  110  supplies a control signal  112  to the starter  100 , in response to the external conditions to which the sensor  110  responds. For example, the sensor  110  could be a conventional ambient light detector, in which case the control signal  112  would be delivered in response to ambient light conditions. In this example, the presence of a predetermined degree of ambient light indicative of normal daylight would result in the assertion of the control signal  112 , and the other ambient light condition indicating natural darkness would result in de-assertion of the control signal  112 . The sensor  110  could also be a conventional motion detector, for example. In this case the control signal  112  would be asserted in response to the detection of movement and would be de-asserted in response to the absence of movement after a predetermined time. The sensor  110  might be a conventional radio receiver, for example. In this example, the radio receiver responds to the reception of a radio signal to assert the control signal  112  and responds to the absence of the radio signal to de-assert the control signal  112 . The sensor  110  could also be a conventional timer which asserts the control signal  112  at a predetermined time and de-asserts the control signal  112  at a later, predetermined time, for example. Many other types of external influences can be sensed by an appropriate sensor  110 , as a basis for asserting and de-asserting the control signal  112 .  
     [0046] In accordance with the present invention, the starter  100  becomes operative and ceases operation in response and relation to the assertion and de-assertion of the control signal  112  from the sensor  110 . For example, when the sensor  110  is a motion detector and the lamp controller  29  thereby functions to detect motion and ignite the fluorescent lamp, the assertion of the control signal  112  causes the starter  100  to ignite the fluorescent lamp. After a predetermined time has elapsed and no further motion has been sensed, the sensor  110  de-asserts the control signal  112 . The starter  100  responds to the de-asserted control signal  112  and functions as described above to extinguish the fluorescent lamp.  
     [0047] The fluorescent lamp controller  29  is combined with a fluorescent lamp, e.g.  20  or  21  (FIG. 1 or  5 ), or with a light fixture  26  (FIG. 2), to obtain the improvements of the present invention in the manner illustrated in FIGS.  9 - 13 . In each case, the lamp controller  29  is either attached to the fluorescent lamp or replaces a conventional starter. The sensor  110  (FIG. 8) is located or oriented to respond to the external influence which it senses, and in response the fluorescent lamp is ignited and extinguished. This added functionality is created by either replacing the fluorescent lamp with a fluorescent lamp that has an attached lamp controller  29 , or by replacing the starter with a lamp controller  29 .  
     [0048] A fluorescent lamp  120  with the lamp controller  29  attached externally to its base  44 , is shown in FIG. 9. The fluorescent lamp  120 , shown in FIG. 9, is similar to the fluorescent lamp  20 , shown in FIG. 1, except that the lamp controller  29  containing the starter  100  and sensor  110  (FIG. 8), is incorporated into the base  44 . The lamp controller  29  is electrically connected to the conductors  36  and  40  from the tube  30  of the fluorescent lamp  120 , thereby achieving the same electrical connection of the lamp controller  29  in the fluorescent lighting circuit  28 , as the starter  80  is electrically connected in the fluorescent lighting circuit  28  (FIG. 6).  
     [0049] Depending on the type of external influence to which the sensor  110  responds, it may be advantageous to include a shield  122  adjacent to the sensor for the purpose of focusing or limiting the response area or field of view of the sensor  110 . For example, if the lamp controller  29  is an ambient light responsive detector, the shield  122  shadows the sensor  110  from the light generated by the lamp  30 . The shield  122  allows the ambient light detector to respond to the ambient light conditions of the room, without the light generated by the lamp interfering with the ability of the detector to respond to ambient light. If the sensor  110  of the lamp controller  29  is a motion detector, the shield  122  limits the responsiveness of the sensor to a specific direction or area in which motion is to be detected. The shield  122  may also include a lens or be replaced by a lens to define the field of view or the field of responsiveness of the sensor  110 . In this regard, the shield  122  is exemplary of a structure used in conjunction with the sensor  110  to define a field of view or field of responsiveness with respect to the external influences which are sensed.  
     [0050] In use, the lamp controller  29  ignites the plasma in the lamp  30  in response to the external influences which it senses, and extinguishes the plasma in the lamp in response to the absence of the external influences which it senses. These benefits may be obtained by the simple expedient of replacing an existing fluorescent lamp with the fluorescent lamp  120  which incorporates the lamp controller  29 . In circumstances where an external starter is normally used with the fluorescent lamp, it is no longer necessary to use the external starter because starter functionality is incorporated within the lamp controller  29 .  
     [0051] Another fluorescent lamp  124  with the lamp controller  29  attached internally within its base  76 , is shown in FIG. 10. The fluorescent lamp  124 , shown in FIG. 10, is similar to the fluorescent lamp  21 , shown in FIG. 5, except that the lamp controller  29  is primarily incorporated in the starter receptacle  74  as a replacement for the conventional starter which is normally used with the fluorescent lamp  21  (FIG. 5). The sensor  110  of the lamp controller  29  is attached at an external surface of the base  76  by electrical conductors which connect it to the remaining components of the lamp controller  29 .  
     [0052] A hollow tube  126  surrounds the sensor  110  and protrudes from one side of the base  76 . The light or other manifestation of the external influence which is sensed enters an open end  127  of the tube  126  and is received by the sensor  110 . In this manner the tube  124  defines a field of view or a field of responsiveness of the sensor  110 . Only that light or other external influence which enters the open end  127  of the tube  126  and reaches the sensor  110  has an affect on the sensor  110 . Although not shown, a lens may be located at the open end  127  to focus light into the tube  126  and onto the sensor  110 , or to establish a larger field of view as would otherwise be established by the tube  126  itself.  
     [0053] The sensor  110  and the tube  126  are oriented on the base  76  of the fluorescent lamp  124  so that when the fluorescent lamp  126  is installed in its normal use position, the field of view or field of responsiveness is directed toward the location where the external influence is to be sensed, relative to the installed position of the fluorescent lamp  124 . For example, if the lamp controller  29  is a motion detector, the sensor  110  and tube  126  are pointed in the direction where the motion is to be sensed, relative to the installed position of the fluorescent lamp  124 . As another example, if the lamp controller  29  is an ambient light detector, the sensor  110  and tube  126  are oriented on the base  76  to point in the direction where the ambient light is to be sensed. In this regard, the tube  126  also functions to block the light generated by the tube  30  of the fluorescent lamp  124  which is outside the field of view or field of responsiveness. Again, the user is able to achieve added functionality from the present invention by simply replacing the existing conventional fluorescent lamp  21  (FIG. 5) with the fluorescent lamp  124 .  
     [0054] The present invention may also be embodied in a fluorescent lamp  128  and a remotely positioned lamp controller  29  as shown in FIG. 11. The fluorescent lamp  128 , shown in FIG. 11, is similar to the fluorescent lamp  20 , shown in FIG. 1, except that an electrical socket  130  is located in the base  44 . A removable electrical connector  132  connects to and mates with the electrical socket  130 . The electrical connector  132  is attached to a two-wire electrical conductor  134 , and the other end of the electrical conductor  134  is connected to the remotely positioned lamp controller  29 . In this manner, the lamp controller  29  may be located at a position remotely spaced from the fluorescent lamp  128 .  
     [0055] The remote lamp controller  29  includes its own starter  100  and sensor  110  (FIG. 8). The remote lamp controller  29  is connected to the fluorescent lamp tube  30  by the electrical conductor  134 , the socket  130  and the connector  132 . The remote lamp controller  29  is confined within a housing  136 , and the sensor  110  of the lamp controller  29  is exposed at the exterior of the housing  136 . A tube  138  is attached to the exterior of the housing  136  in a position which surrounds the sensor  110 . The tube  138  defines a field of view or field of responsiveness within which the external influences cause the sensor  110  to respond. In this regard, the tube  138  functions in a similar manner to the tube  126  (FIG. 10).  
     [0056] The socket  130 , connector  132  and electrical conductor  134  permit the lamp controller  29  to be positioned at a remote location relative to the fluorescent tube  30 . The lamp controller  29  can be remotely located in an advantageous position to sense the external influences, and any unwanted influence created by the light from the fluorescent lamp  128  may be moderated or eliminated by the remote location of the lamp controller  29 . Even at the remote location, the tube  138  may be used in an advantageous manner similar to the use of the tube  128  (FIG. 10), because the tube  138  protrudes from the housing  136  to facilitate or limit the definition of the field of view or the field of responsiveness of the sensor  110 . For example, in the case of the lamp controller  29  performing an ambient light sensing function, the remote lamp controller  29  is placed at a location away from the light fixture to prevent the sensor  110  from responding to the light generated by the fluorescent lamp  128 .  
     [0057] Again, with respect to the fluorescent lamp  128 , the user is able to obtain the added functionality from the present invention by replacing the conventional fluorescent lamp  20  (FIG. 1) with the fluorescent lamp  128  and connecting the remotely located lamp controller  29  to the fluorescent lamp  128  by connecting the connector  132  into the socket  130 . No external starter is needed for the fluorescent lamp  128 , because the lamp controller  29  performs the starter functionality.  
     [0058] Improvements of the present invention may also be obtained without replacing a conventional fluorescent lamp fixture  26  in the manner shown in FIG. 12. An adapter  140  is connected into the conventional starter socket  56 . A remotely located lamp controller  29  is electrically connected to the adapter  140  by an electrical conductor  142 . The remotely located lamp controller  29  shown in FIG. 12 is similar to the one described and shown in FIG. 11. Since the lamp controller  29  also contains the starter  100  in addition to the sensor  110  (FIG. 8), the adapter  140  simply electrically connects the lamp controller  29  to the fluorescent lamp  20  in the light fixture  26  in the same manner that a conventional starter is connected in the lighting circuit  28  (FIG. 6). However, the sensor of the lamp controller  29  responds to external influences in the same manner previously described in connection with FIGS.  9 - 11 . The remotely located lamp controller  29  obtains the added functionality from the light fixture  26  without replacing the light fixture, by simply replacing the conventional starter which normally fits within the starter socket  56  with the adapter  140  and positioning the remotely located lamp controller  29  at the desired location to respond to the external influences within the field of view or the field of responsiveness.  
     [0059] Improvements of the present invention may also be obtained by simply replacing the conventional starter with a lamp controller  29 , as shown in FIG. 13. The lamp controller  29  provides the functionality of both the starter  100  and the sensor  110  (FIG. 8) incorporated within a housing  144 . The sensor is located at the exterior of the housing  144 , and a tube  138  defines a field of view or field of responsiveness for the sensor in the same manner as has been previously described in conjunction with FIGS. 11 and 12. The tube  138  may be made long enough, or may be made out of conductive material such as fiber optic material, to conduct the manifestation of the external influence which is sensed to the sensor. The sensor itself can be located on the terminal end of the tube  138 , or a lens may be used to direct light through the tube  138  to the sensor. In any event, the tube  138  is oriented to obtain the desired field of view or field of responsiveness. In most cases, the desired field of view or field of responsiveness will be directly away from the light fixture  26  because the tube  138  is oriented to detect external influences directly away from the light fixture  26 . In this manner, added functionality is obtained from the light fixture  26  in accordance with the present invention.  
     [0060] As is apparent from the previous description, the starter functionality of the fluorescent lamp controller  29  has the capability of igniting and extinguishing the fluorescent lamp on a reliable and consistent basis. Incorporating the sensor in the lamp controller permits the starter functionality to be controlled in response to the external influences which are sensed, thereby adding additional functionality to the fluorescent lamp or the fluorescent lamp light fixture. Moreover, by incorporating the functionality of the fluorescent lamp controller  29  into the fluorescent lamp itself or into a housing which can be remotely positioned and connected to the fluorescent lamp, or by connecting the fluorescent lamp controller  29  into a fluorescent lamp light fixture, a user or consumer can easily obtain the added functionality by simply replacing the conventional fluorescent lamp or fluorescent starter as described above. The added functionality is obtained in this manner without requiring the services of a skilled electrician to wire additional components to an existing fluorescent lamp light fixture or to change to the standard fluorescent lamp light circuit  28  shown in FIG. 6. Preserving the conventional fluorescent lamp lighting circuit  28  (FIG. 6) in its conventional form also facilitates the direct and simple replacement of the conventional fluorescent lamp and starter with those items of the invention as described above. For example, if a different type of fluorescent lamp controller was used which employed a so-called electronic ballast, the conventional fluorescent lamp lighting circuit  28  would have to be altered to eliminate the magnetic ballast  84  (FIG. 6). Such alterations would require the services of a skilled electrician. The lamp controller  29  of the present invention operates in a conventional fluorescent lamp lighting circuit  28  in place of the conventional starter to provide its significant improvements. Other improvements will be apparent upon gaining a full understanding of the present invention.  
     [0061] Presently preferred embodiments of the invention and many of its improvements have been described with a degree of particularity. This description is not necessarily intended to limit the scope of the invention. The scope of the invention is defined by the following claims.