Abstract:
A flood light lamp removal alarm for security lights mounted on or near a home, wherein the lights are designed to turn on automatically if a motion detector is triggered and the ambient light level is low, detects if any of the flood light lamps are unscrewed or loosened, either prior to a burglary or during the attempt to disable the flood light assembly. A central contact of a lamp socket is modified so that it maintains contact with the lamp therein for a longer distance as the lamp is unscrewed out, so that the alarm is triggered before the light from the lamp is disabled. Alternatively, current detectors verify when a lamp is loosened from a socket by detecting changes in current draw across the socket.

Description:
This application is a continuation of application Ser. No. 09/410,908, filed Oct. 2, 1999, now U.S. Pat. No. 6,078,257. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a home security device. 
     BACKGROUND OF THE INVENTION 
     Many homeowners have security lights mounted on or near their home. Some of these lights are designed to turn on automatically if a motion detector is triggered and the ambient light level is low. These lights are a deterrent to burglary. Unfortunately, they can be easily defeated if the lamps are unscrewed or loosened either prior to the burglary or during the attempt. 
     In addition, if the lights are loosened by natural forces, such as vibrations from passing heavy trucks, etc., abrupt jarring motions, such as foundation loosening, machinery movement, sound, repetitive motions etc., then the lamps will also be loosened. Moreover, a loosened lamp would not be noticed during daylight hours. 
     Various attempts have been made to provide lamp failure devices. U.S. Pat. No. 5,099,177 of Taniguchi discloses a lamp circuit with disconnected lamp detecting device. U.S. Pat. No. 4,980,672 of Murphy discloses an overhead socket smoke detector with theft alarm. 
     U.S. Pat. Nos. 4,396,868 and 5,168,198 of Watanabe discloses a lamp circuit with disconnected lamp detecting device and a lamplight failure detection system respectively. U.S. Pat. No. 5,359,325 of Ford discloses an automatic monitoring system for airfield lighting systems. 
     Furthermore, U.S. Pat. No. 5,387,909 of Neel discloses a lamp sensing system for traffic light. In addition, U.S. Pat. No. 5,034,659 of Taniguchi describes a lamp circuit with a disconnected lamp detecting device. U.S. Pat. No. 4,700,126 of Hill shows a vehicular lamp circuit tester. 
     Moreover, U.S. Pat. No. 4,438,421 of Toyomura discloses an electronic device having a warning means and U.S. Pat. No. 4,295,079 of Otsuka describes a lamp circuit with a disconnected lamp detecting device. U.S. Pat. No. 4,422,068 of Helft discloses an intrusion alarm system for preventing actual confrontation with an intruder. 
     In addition, U.S. Pat. No. 3,975,627 of Huber shows a burglar-proof guard for light bulbs and U.S. Pat. No. 4,936,789 of Ugalde shows a method and apparatus for preventing the theft of a fluorescent lamp and ballast transformer. 
     Among other prior art includes U.S. Pat. No. 4,812,827 of Scripps which describes a detector and light assembly and U.S. Pat. No. 5,406,129 of Gilmartin which describes a flashing locator switch control with built-in lamp operation test. 
     Other prior art includes U.S. Pat. No. 3,382,494 of Mahacsek which describes a theft alarm for an electrical device; U.S. Pat. No. 4,021,679 of Bolle et al., which describes a method and apparatus for automatic switching; U.S. Pat. No. 4,369,435 of Adachi et al., which describes a fire detector and fire alarm system having circuitry to detect removal of one or more detectors at a signal station; U.S. Pat. No. 5,155,474 of Park et al., which describes a photographic security system; U.S. Pat. No. 5,160,000 of Agha et al., which describes an attache and umbrella carrying case; U.S. Pat. No. 5,172,098 of Leyden et al., which describes an alarm system sensing and triggering apparatus; U.S. Pat. No. 5,266,920 of Langner which describes a magnet for use on a refrigerator or the like; U.S. Pat. No. 5,293,115 of Swanson which describes a method and system for sensing removal of a utility meter from its socket; and U.S. Pat. No. 5,434,558 of Zeder which describes an annunciator apparatus for monitoring electrical connections. 
     While the prior art teaches a variety of methods for failed lamp detection and even an alarm for detecting removal of a smoke detector from a socket, the applications are very specialized. 
     In contrast to the prior art, the present invention sets off an audible or silent alarm when an ordinary bulb or flood lamp is loosened or removed from the socket of a single or multi-lamp security light fixture. Furthermore, the alarm remains on or otherwise indicates that an incident had occurred even if the lamp is immediately retightened in its socket. This action is achieved using inexpensive switch elements and electronic subsystems consistent with the product cost limitations dictated by this consumer market. 
     In other embodiments, the present invention allows the alarm to be set off even before a bulb is removed from a socket, while still lit. The present invention can also detect removal of a lamp by detecting changes in current in the lamp socket. 
     OBJECTS OF THE INVENTION 
     It is therefore an object of the present invention to provide a home security device which detects unwarranted removal of a flood light lamp. 
     It is yet another object to provide a flood light lamp removal alarm which is a deterrent to burglary. 
     It is yet a further object to provide a flood light lamp removal alarm which is activated if the lamps are unscrewed or loosened, either prior to a burglary or during an attempt to disable the flood light assembly. 
     It is yet another object to provide a flood light lamp removal alarm which detects if lights are loosened by natural forces, such as vibrations from passing heavy trucks, etc., abrupt jarring motions, such as foundation loosening, machinery movement, sound, repetitive motions etc. 
     It is yet another object to provide a flood light lamp removal alarm which causes a discernible alarm to go on, thereby startling a burglar and alerting the neighbors if a lamp is unscrewed from a security light. 
     Another object of this invention is to modify the central contact of a lamp socket so that it maintains contact with the lamp for a longer distance as the lamp is unscrewed. This would insure that the removal alarm switch is triggered before the light from the lamp is disabled. 
     Another object of this invention is to modify the central contact of a lamp socket so that it maintains contact with the lamp until the lamp is totally unscrewed from the socket. The lamp would not be disabled simply by loosening it. 
     A further object of this invention is to detect current draw by the lamps and send this signal to a controller so that an alarm is set off if no current is drawn by a lamp after the motion detector had signaled to switch on the power to the lamps. This would detect missing lamps, loosened lamps as well as burned out lamps. 
     Yet another object of this invention is to use a combination of a motion detector with auxiliary battery and radio transmitter in a distributed lamp security system along with current sensors to detect tampering with the lamp fixture even if the power line to the motion detector is severed. 
     It is yet another object to improve over the disadvantages of the prior art. 
     SUMMARY OF THE INVENTION 
     In keeping with these objects and others which may become apparent, the present invention includes a flood light lamp removal alarm for security lights mounted on or near a home, wherein the lights are designed to turn on automatically if a motion detector is triggered and the ambient light level is low. The alarm detects if any of the flood light lamps are unscrewed or loosened, either prior to a burglary or during the attempt to disable the flood light assembly. 
     The alarm can also be used for other lighting fixtures, wherein a lamp is screwed into a socket, such as in a decorative lighting system, an industrial building, or a signaling system, and the like. 
     In the preferred embodiment, the central contact of a lamp socket is modified so that it maintains contact with the lamp therein for a longer distance as the lamp is screwed out, so that the alarm is triggered before the light from the lamp is disabled. 
     In yet another embodiment, current detectors verify when a lamp is loosened from a socket by detecting changes in current draw across the socket. 
     In addition, the alarm also detects if the lights are loosened by natural forces, such as vibrations from passing heavy trucks, etc., abrupt jarring motions, such as foundation loosening, machinery movement, sound, repetitive motions etc. 
     If one or more lamps are loosened, the alarm of the present invention causes the discernible alarm to go on, thereby startling a burglar and alerting the neighbors if a flood light lamp is unscrewed from a security light while the switch inside the house is turned on, regardless of whether the lamp is on or off. 
     A housing is provided for the alarm, wherein the housing contains control circuitry and a discernible alarm, such as an audio alarm, for example, an electronic sound generator. The electronic sound generator may be an oscillator or siren type of sound generator, or either a magnetic or piezoelectric sound transducer or loudspeaker. 
     The trigger for the alarm may be a detection device with a snap action switch, which is activated by an insulating rod. The insulating rod is physically pushed by the lamp base when the lamp base is properly screwed into the socket. The alarm is activated when the detection rod is pushed away by the restoring spring in the switch. 
     In the alternate, the snap action switch can be replaced by a photodetector in the lamp socket which detects the proper position of the lamp. 
     The alarm is powered by a low voltage DC power supply formed by a transformer connected at one side to a 120 volt AC power supply and on the other side to a diode and capacitor connected to a plurality of switches, such as single pole, single throw (SPST) switches located within the lamp sockets. The switches are wired in parallel so that any of the switches can turn on the alarm, if any bulb is removed in an unauthorized manner. 
     In an alternate embodiment, the flood light lamp removal alarm may be remotely placed away from the lamp fixture, such as with a wireless communication device. 
     The lamp sockets may alternately include a compressive switch for detecting the lamps of a flood light lamp fixture. In the compressive switch, contacts are provided such that the contacts close when the lamp is properly screwed into the socket. 
     Therefore, a simple in-socket switch is provided within each socket, to detect the unwarranted loosening or removal of any flood light lamps of a home security flood light assembly. 
     In a preferred embodiment, the means for detecting removal of the lamp includes a physical condition sensor within each socket. The physical condition sensor is inactivated when the lamp is properly screwed into said socket, and the physical condition sensor is activated when the lamp starts to be loosened or removed from the socket. Preferably, the socket is provided with a resilient electrical contact member for maintaining lamp-illuminating electrical contact during the partial removal of the lamp from the socket. 
     To an unsuspecting vandal, even partial removal of a flood light lamp triggers the lamp removal alarm, even while the partially removed lamp remains illuminated by electrical contact with the resilient contact member. 
     The resilient electrical contact member may include an elongated leaf spring for maintaining electrical contact with a lamp during the loosening or partial withdrawal of the lamp from the socket. 
     The resilient electrical contact member can also be an electrically conductive coil spring, having a central electrical contact member, such as an upwardly extending rod, in combination with and surrounded by an electrically insulating compressible sleeve, such as a bellows or a telescopic cylinder. 
     The coil spring and sleeve combination is mounted within the socket for extensible electrical contact of the lamp with the central contact member, for providing illuminating current during partial removal of the lamp from the socket. 
     The physical condition sensor means can also include an electric circuit separate from the lamp illuminating electrical circuit. The physical condition sensor circuit may have a switch having an electrically insulated narrow actuator rod disposed in the bottom of the socket and the narrow actuator rod may have a “throw ” member and may be compressible when pressed upon by a fully seated and tightened lamp in the socket. The switch may have a no-alarm condition when the narrow actuator rod is depressed by a fully-seated lamp and the switch may have an alarm condition when the narrow actuator rod is not compressed due to the absence of a fully seated condition of the lamp. 
     In other embodiments, the physical condition sensor may be a current detector, such as a Hall effect switch, detecting changes in current in the socket when a lamp is removed. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     The present invention can best be understood in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a perspective view of the flood lamp/alarm fixture of one embodiment of the present invention; 
     FIGS. 2A and 2B are cross section views of the socket portion of the fixture as in FIG. 1; 
     FIG. 3 is an electrical schematic diagram of the present invention as in FIG. 1; 
     FIG. 4 is a perspective view of an alternate remote alarm system; 
     FIG. 5 is a cross section view of the system as in FIG. 4; 
     FIG. 6 is a close-up view of the compressive switch element as in FIG. 4; 
     FIG. 7 is an electrical schematic of the alarm triggering as in FIG. 4; 
     FIG. 8 is a block diagram of an automatic dialer interface for the present invention as in FIG. 1 or FIG.  4 . 
     FIG. 9 is a front view of a second alternate embodiment or a lamp fixture of the present invention; 
     FIG. 9A is a detail of a socket of the lamp fixture as in FIG. 9, shown with a lamp screwed in tight; 
     FIG. 9B is a detail shown of a socket of the lamp fixture as in FIG. 9, shown with a lamp loosened; 
     FIG. 10 is a front view of a third alternate embodiment for a lamp fixture of the present invention; 
     FIG. 10A is a detail of a socket of the lamp fixture as in FIG. 10, shown with a lamp screwed in tight; 
     FIG. 10B is a detail of a socket of the lamp fixture as in FIG. 10, shown with a lamp removed; 
     FIG. 11 is a block diagram and logic of a fourth alternate embodiment of the present invention, shown with current sensors; and 
     FIG. 12 is a block diagram of a fifth alternate embodiment of the present invention, for a distributed lamp security system. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As shown in an embodiment shown in FIGS. 1-3, FIG. 1 shows a two flood lamp security fixture  10  for a pair of flood light lamps  12 ,  14  screwed into sockets  12   a ,  14   a . Sockets  12   a ,  14   a  within socket housings  12   c ,  14   c  are connected to alarm control housing  16  and conventional motion detector  18 , which detects movement in low light conditions in conjunction with ambient light detector  19 . 
     Fixture  10  appears visibly undetectable since lamp security fixture  10  looks quite ordinary. However, housing  16 , which normally contains control circuitry  20 , also contains audio alarm  22 . Housing  16  may be somewhat larger than normal to accommodate audio alarm  22 , and it may have sound escape holes or louvers  24 . Audio alarm  22  itself includes electronic sound generator  26 , such as an oscillator or siren type of sound generator, and either a magnetic or piezoelectric sound transducer or loudspeaker. 
     As shown in FIGS. 2A and 2B, a method of lamp detection is employed to trigger audio alarm  22 . One method is to equip each lamp socket  12   a ,  14   a  with miniature snap-action switch  28 , which switch  28  is activated by an insulating rod  30 , which insulating rod  30  is physically pushed by the lamp base  12   b  or  14   b , of lamp  12  or lamp  14 , into a first predetermined position, when lamp  12  or lamp  14  is properly screwed in sockets  12   a  or  14   a.    
     Detection rod  30  is pushed away from the first predetermined position to a second predetermined position by restoring spring  32  in snap-action switch  28 , if lamp  12  or lamp  14  is loosened or removed, such as shown in FIG. 2A with respect to lamp  12 . 
     In this configuration in FIG. 2A, switch  28  is in the “ON” position and audio alarm  22  is turned on, regardless of lamp  12  itself being “on” or “off”. 
     In FIG. 2B however, detection rod  30  is pushed down by lamp  12  so that switch  28  is turned off. Snap-action switch  28  can be replaced by a photodetector in the socket housing  12   c  or  14   c  that detects the proper position of lamp  12  or lamp  14 . 
     Another alternative retains detection rod  30  but wherein detection rod  30  actuates either a hall-effect sensor or an electronic photodetector switch, either of which is shaped like snap-action switch  28 . In any event, the detection of the proper positioning of lamp  12  or  14  in their respective sockets  12   a ,  12   b  is made at this location. 
     FIG. 3 shows a block diagram of the security lamp system with a wiring diagram for adding the alarm feature. Here, alarm  22  is wired directly to the switch 120 volt AC line that feeds the entire fixture. Transformer T 1 , diode D 1 , and capacitor C 1  form a small low voltage DC power supply to power alarm  22 . The voltage output is preferably from 5 to 12 volts as appropriate. 
     Control circuit  20  of the security lamp system also has a DC power supply internally which is used to power alarm  22  instead of transformer T 1 , diode D 1  and capacitor C 1  if the feature is integrated with the security lamp feature. 
     S 1  and S 2  describe two single pole single throw (SPST) switches normally on snap-action switches, such as switch  28 , located in lamp socket housings  12   c ,  14   c . Switches S 1 , S 2  are wired in parallel so that either switch S 1  or switch S 2  can turn alarm  22  on if either lamp  12  or lamp  14  is unscrewed or loosened from lamp socket  12   a  or lamp socket  14   a . For a single lamp, only one switch is used. For any number of multiple lamps, there is generally one switch per socket and they are generally wired in parallel. 
     The homeowner can easily change lamp  12  or lamp  14  without triggering alarm  22  by simply switching the security lamp off from a conventional on-off switch inside the house. 
     In an alternate embodiment, shown in FIGS. 4-7, alarm  122  for lamps  112 ,  114  is remotely placed away from security lamp fixture  110 . This necessitates the use of a cable connection  140  from alarm  122  to security lamp fixture  110 , as in FIG. 4, unless an alternate wireless communication scheme is used from fixture  110  to alarm  122 . The latter can be a radio frequency or infrared communication link from the sensors in lamp fixture  110  to the alarm triggering circuit. 
     Another “wireless” option is to use the power wiring itself (house 120V AC wiring) as the signaling connection. A typical sophisticated encoding scheme that puts a signal carrier onto the power wiring is manufactured by ECHELON Corporation. 
     In the remaining description, cable connection  140  is described. Cable connection  140  is preferably hidden or armored so that it would be difficult to tamper with it. 
     Two alternate powering schemes are shown for remote alarm  122 . One is an AC connection through a wall mounted alarm defeat switch  152  inside the house. 
     A second approach is to feed low voltage DC from inside the house either provided by battery pack  154  or an AC connected power supply. This alternative simplifies wiring to alarm  122  since only low voltage DC need be wired, as a safety consideration. This latter alternative has alarm defeat switch  152  mounted on the power supply or battery pack  154 . In any event, defeat switch  152  is required to permit the homeowner to change lamps  112 ,  114  in fixture  110  without triggering alarm  122 . 
     FIG. 5 shows a cross section of an ordinary lamp socket  112   a  of housing  112   c  modified to include a compressive switch lamp screw-down detection element  130 . A hole is drilled through the side of socket housing  112   c  and through the lamp screw socket connector  112   a  at the level of the center spring contact  132 . Compressive switch element  130 , as in FIG. 6, is slid through this access hole placing switch element  130  directly under spring contact  132 . Switch connecting cable  140  is then sealed with an elastomeric sealant around its entry to socket housing  112   c.    
     FIG. 6 reveals that compressive switch element  130  is simply a spring contact  130   a  and a rigid contact  130   b  encased in an elastomeric bulb  130   c , which is sealed around contact housing  130   d  and sensor cable insulation  140   a . The material of bulb  130   c  as well as cable insulation  140   a  in the vicinity of the lamp socket  112   c  must be high temperature insulators such as silicone material. 
     The operation of the compressive switch  130  is such that contacts  130   a ,  130   b  are closed when lamp  112  is properly screwed into socket  122   a . Contacts  130   a ,  130   b  open and break an electrical circuit if lamp  112  is loosened or removed. Although switch  130  itself in an SPST normally open type, in operation with lamp  112  screwed in, switch  130  will be in the “ON” position. 
     Therefore, if multiple switches  130  are used to detect loosening in multi-lamp fixtures, they are preferably wired in series as shown in FIG. 7, such as S 3  and S 4 . In this way if any one lamp  112  is loosened, or if the cable is cut, alarm  122  will be triggered. 
     FIG. 7 shows an alarm triggering circuit with several features. It is assumed that sensor switches S 3 , S 4  are of the compressive switch type. A simple circuit change easily accommodates one or more switches S 3 , S 4 , wired in parallel of the type shown in FIGS. 2 and 3. 
     The triggering circuit detects any attempted tampering even if lamp  112  is quickly screwed back in. Alarm  122  stays on for a period of time determined by the delay interval timer  124  and a tell-tale indicator lamp or light emitting diode (LED) remains on until manually turned off by the homeowner, indicating that alarm  122  had been triggered. 
     There are many possible implementations of this control scheme. FIG. 7 shows one embodiment. The circuit consisting of resistor R 1 , capacitor C 2  and a “schmidt”trigger inverter I form a signal conditioning circuit for the two sensor switches, S 1  and S 2 . The inverter I is preferably an SN74HC14 type from Texas Instruments, for example. Resistor R 1  can bias the input to the inverter I “HIGH”, except for the fact that S 1  and S 2  are usually closed, thereby shorting this input to ground. 
     Capacitor C 2  is used to “quiet” the circuit, making it more immune to minor disturbances, such as lightning or power interferences that may disturb long sensor cable  140 . If lamp  112  is loosened, one of the switches opens, thereby permitting resistor R 1  to pull up the inverter I input. Although capacitor C 2  will slow this transition, the use of a “schmidt” trigger type of inverter insures a crisp “HIGH”to “LOW” transition at the output of inverter I, which sets latches L 1  and L 2 , since these are of the “low edge triggered” variety. 
     Even if the input condition goes away, e.g. lamp  112  is quickly screwed back in, latches L 1 , L 2  remain set. Latch L 1  immediately sets off alarm  122  for a period determined by delay interval timer  124  which then resets latch L 1 . However, latch L 2  stays on, powering the LED until the user manually presses the momentary SPST switch S 5  to reset the latch L 2 , thereby turning the LED off. The LED and switch S 5  are preferably in an accessible location, such as on an indoor panel or power supply. 
     FIG. 8 shows an automatic dialing feature for either of the embodiments in FIG. 1 or FIG.  4 . Stand-alone automatic message dialers have been commercially available for some time. A model 49-434 from Radio Shack is currently available. By adding automatic dialer  301  to the basic alarm circuit shown in FIG. 7, the flood lamp removal alarm  122  is able to automatically dial up to three phone numbers automatically. The unit is attached to its own power supply and to the telephone line. It has a numeric keyboard for entering the phone numbers and a digital recorder with built-in microphone for recording a short phone message to be sent. 
     FIG. 8 shows the interface circuitry required to connect dialer  301  to the flood light alarm removal alarm  122 . The dialer input is set up to monitor “contact closure”. A pair of normally closed single pole contacts (SPST) on relay RL 1  are used to trigger the automatic message dialer  301 . Relay RL 1  is driven by an emitter-follower amplifier consisting of a transistor (Q 1 ), such as an NPN transistor and a base resistor (R 3 ). Relay RL 1  is energized whenever the LED indicator is turned on by latch L 2 . This, in turn, causes contacts  130   a ,  130   b  to open, thereby triggering automatic message dialer  301 . By turning off audible alarm  122 , or eliminating it, flood lamp removal alarm  122  can function as a “silent alarm” dialing the appropriate authorities. 
     Other types and models of automatic message dialers are also available. Some may not require the relay as part of the interface. Also, the entire function of the stand-alone dialer can be built into the flood lamp removal alarm. 
     Conventional lamp sockets have a central contact with a short throw; it includes of a short leaf spring which loses contact with the lamp central contact when the lamp is loosened a short distance. A lamp removal detector switch which senses vertical motion of the lamp bottom away from this contact should be quite sensitive, i.e. a short throw, and should be adjusted well to reliably detect the loosening of a lamp before it is disabled. Another problem is that false triggering may result if a lamp is replaced but not screwed in tightly enough to trigger the switch to its normal position (even though the lamp may light). 
     FIG. 9 shows lamp fixture  401  with flood light lamp  402  screwed within socket  404 , and lamp  403  screwed within socket  405 . 
     FIGS. 9A and 9B show details of a modified type of lamp socket which uses a longer leaf spring  408  with an extended contact range to overcome these problems, wherein lamp fixture  401  is shown with lamps  402  and  403  in sockets  404  and  405  respectively. For example, a conventional leaf spring is about ¾ to ⅞ inch in length, wherein the oblique portion is roughly ⅜ to ½ inch and the horizontal bulb contact portion is ⅜ inch. However, in the present invention, the oblique portion, as shown in FIGS. 9A and 9B, is increased by about 30 to 50 percent in length, or about ½ to ¾ inch more, to increase the contact time as a bulb is being removed, so the alarm can go off before the lamp goes off. 
     In FIG. 9A, the lamp removal switch  406  of socket  404  is shown with button  407  depressed by lamp  402  through leaf spring  408 . This is the “no alarm” position. 
     On the other hand, FIG. 9B shows the situation with lamp  403  of socket  405  somewhat partially unscrewed. Button  407  on lamp removal switch  406  is fully extended even though contact  408  is still connected to lamp  403 , thereby lighting lamp  403 . 
     Therefore, if a person unscrews lamp  403  for the normal amount of unscrewing that would disconnect lamp  403  from socket  405 , lamp  403  might actually not be disconnected and alarm switch  406  will be triggered reliably. 
     This “partial unscrewing” alarm feature is desirable even if a lamp removal switch and alarm is not used. A user familiar with the socket is just cautioned to continue screwing lamp  403  further after a slight resistance is first encountered, to reset removal switch  406 . Switch  403  may alternatively have a longer throw that can be used, and therefore it would not have to be as accurately adjusted. 
     FIG. 10 shows an alternate embodiment that goes farther with the extended contact concept, such that lamp  502  of socket  510  or lamp  503  of socket  511  each are in contact with respective switches  506  until each lamp  502  or  503  is physically removed from respective sockets  510  or  511 . This feature is useful even without a removal sensor switch and alarm. A person tampering with lamp  502  or lamp  503  to loosen lamp  502  or lamp  503 , so that lamp  502  or lamp  503  do not light, would literally have to remove either lamp  502  or lamp  503  completely, which is easily visible, before lamp  502  or lamp  503  cease to light. 
     In FIG. 10A, lamp  502  is shown screwed in tightly in socket  510 , while in FIG. 10B, lamp  503  is shown removed from socket  511 . 
     In FIG. 10A, socket  510  includes central contact  513  that is attached to coil spring  516 , which carries the lamp current. Narrow actuator rod  515  on removal sensor switch  506  is threaded through the center of coil spring  516 . Narrow actuator rod  515  tends to keep coil spring  516  from deforming sideways. 
     A high temperature insulating bellows  514  is shown in cross section. Insulating bellows  514  can be molded of a material, such as silicone. Insulating bellows  514  is used to prevent any chance of a short circuit with side lamp contact  519 . Alternatively, a three-sectioned telescoping cylinder can be used as a replacement for the bellows. Insulated leads  517  and  518  complete the circuit to power lamp  502  or lamp  503 . 
     FIG. 10A shows rod  515  in its compressed “no alarm”position. 
     In contrast, FIG. 10B shows when lamp  503  is removed from socket  511 , and the central contact  513  of socket  511  is totally extended almost to the top of side contact  519 . Central contact  513  has a depression in its top to help center it and engage the center lamp contact  512  of lamp  502 . Rod  515  is now fully extended and switch  516  is in its “alarm” condition. 
     FIG. 11 shows an alternate embodiment with the alternate use of, or the addition of, current sensors to the lamp security system. In this embodiment, motion detector  621  signals control circuit  620  to turn on lamps  623  and  624 . A separate current sensor  626  is used for each lamp  623  or  624  in this diagram. An alternate embodiment using a single sensor  626  that can sense the difference between the current of both lamps  623  and  624  and that of a single lamp  623  or  624  can also be used. 
     Current sensors  626  used are preferably Hall effect switches  626 , which sense the magnetic field in the open gap of each ferrite core  625 , due to current flowing in a few turns of conductor  630  wound around each core  625 . 
     Therefore, if lamp  623  or lamp  624  were missing, loosened, or burned out, no current would flow in respective associated coils  630  and each sensor  626  would be in an “Off” state. 
     Alternate sensor technologies such as current sensing relays or a low value resistor in series with each lamp  623  or  624  with an op-amp type comparator sensing the voltage drop across it can be used as well. In this embodiment, the output of each sensor  626  is inverted in respective inverters  627  and then the two signals are logically OR&#39;ed in block  628 . The output is AND&#39;ed with the motion detector “activate” signal in block  629  to form the alarm condition signal to the control circuit. The sensors and logic blocks are actually part of the control circuit but are shown externally for clarity. The logic blocks may preferably be “74COO” series CMOS integrated circuits such as those available from National Semiconductors Inc. In this manner, if either lamp  623  or  624  is inoperative, or both, when motion detector  621  is calling for them to be activated, the control circuit sounds the alarm. 
     Current sensors  626  of the current sensing embodiment of FIG. 11 can be used in addition to lamp removal sensor switches  406  OR  506  or instead of them. 
     Moreover, current sensors  626  do not sense a problem until motion detector  21  is triggered, while lamp removal sensor switches  406  or  506  do not detect a burned out bulb, but they operate independently of motion sensor  621 . Thus better coverage is afforded if both types of these embodiments are used together. 
     FIG. 12 shows a layout for a further alternate embodiment for a distributed lamp security system. The perimeter of a dwelling or building, such as house  740 , shows a motion detector (MD) subassembly  742  mounted remotely from lamp fixture  741 . Control unit  743  and alarm  746  are located inside house  740 . Plug  747  supplies  120  volts AC to power motion detector (MD) subassembly  742 . Control unit  743  supplies power to lamps of lamp fixture  741  through current detector (CD)  744  if motion is detected by motion detector  750 . Motion detector (MD) transmitter  751  alerts control unit  743  with a coded burst of radio signals which are received in a wireless fashion by motion detector (MD) receiver  745  inside house  740 . Since motion detector  750  is powered through an AC to DC converter  748  with a storage battery  749  on “float charge”, motion detector  750  functions for a number of hours even if the power line to motion detector  750  is cut. 
     Similarly, if the power line is cut to lamp fixture  741 , current detector  744  will sound the alarm the very next time motion detector  750  is triggered. Current detector  744  senses the difference between the current of both lamps of fixtures  741  and that of only one. Current detector  744  triggers an alarm set condition if less than full 2-lamp current is detected. This alarm set condition turns into an alarm signal if it happens simultaneously with a signal burst of motion detector  750 . 
     The above examples are illustrative of the concept described in the preferred embodiments. However, other embodiments may be made to the present invention for a flood light lamp removal alarm.