Abstract:
Protection against abusive ringing of doorbells is provided by a ring limiting circuit including ring counter and ring timer circuits. Protection can also be implemented in software executed by a digital processor such as a smart home central controller in a wireless doorbell installation.

Description:
This is a Continuation-in-part of application Ser. No. 10/619,733, filed Jul. 14, 2003 which is now U.S. Pat. No. 6,965,301. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   This invention pertains to the field of doorbells, ringers and other signaling devices such as are installed near a doorway of a dwelling and used to announce the arrival of visitors. 
   2. State of the Prior Art 
   Exterior doors of homes and other dwellings are commonly equipped with a doorbell by which a visitor may announce him or herself to those inside the dwelling. The doorbells typically include a push-button electrical switch mounted on an exterior wall or other support outside the dwelling. The doorbell switch is operatively connected, either by electrical wiring or a wireless link, to an interior signaling device such as an electromechanical ringer or electronic tone generator mounted inside the dwelling. The interior signaling device is actuated when the exterior doorbell switch is pressed by a visitor. 
   Such doorbells are, however, subject to abuse when repeatedly or continuously pressed by pranksters or others intent on annoying or harassing the occupants of the dwelling, or simply by an impatient visitor who repeatedly or continuously rings the bell until someone responds. 
   Three forms of abusive doorbell ringing can be identified. A first form of abuse occurs when the door bell is rung repeatedly many times in rapid succession within a relatively short period of time. A second form of abuse occurs when the door bell is rung only a few times but with rings of excessively long duration, such that each ring alone would not be objectionable but in combination the rings add up to excessive bell ringing time within some preset time interval. A third form of abuse occurs where the door bell is rung only once but is rung continuously for an unacceptably long time. 
   Many modern doorbells are partially protected from abuse in that actuation of the ringer results in playback of a musical tune or sound effect stored in the signaling device, and repeated actuation of the doorbell is ineffective until the tune or sound effect has played out. However, when a short tune or sound effect is selected by the homeowner, the doorbell can be rung repeatedly at an annoyingly high rate. Even long-playing tunes can be replayed unnecessarily. And in continuous ring mode, the doorbells are subject to all forms of abuse mentioned earlier. 
   Existing doorbell installations lack adequate protection against such abuse and as of yet no practical solution has been proposed to this problem. A continuing need exists for doorbells with built-in protection against harassment caused by abusive ringing of doorbells. 
   SUMMARY OF THE INVENTION 
   The aforementioned need is addressed by the invention disclosed herein and which provides an improvement in a doorbell installation of the type having a ringer device such as a push button switch, mounted near an exterior doorway or gate to a dwelling and connected for operating a signaling device, such as an electric bell, buzzer or audio sequence generator, at a location remote from the actuating device where the signal can be heard by occupants of the dwelling or other premises. 
   The improved doorbell system of this invention can be configured with different combinations of features selected to prevent any one or more of the aforementioned three forms of abusive doorbell ringing. 
   In a relatively full featured embodiment, the improvement according to this invention includes timer circuits connected for disabling the ringer device for a predetermined rest interval upon the occurrence of one or both of a predetermined total number of actuations of the signaling device within a preset base time interval, or actuations having a total ring duration in excess of a preset total ring length within the preset base time interval irrespective of the number of actuations within the preset base time interval. 
   The timer circuits may include a base interval timer which is preferably self resetting upon lapse of the base time interval, a ring frequency counter for accumulating a count of ring actuations during the base time interval, and a rest interval timer actuated by the ring frequency counter for timing the rest interval. A ring length timer may be provided for accumulating a total length of ring actuations during the base time interval, and connected for starting the rest interval timer if the total ring length equals the preset total ring length. The rest interval timer is connected for interrupting further actuation of the signaling device after it is started and until the rest interval has timed out. The rest interval is also connected for resetting the base interval timer, the ring frequency counter and the ring length timer upon lapse of the rest time interval thereby resetting the protection system. 
   Either or both the predetermined number of ring actuations, the total ring length, the base time interval and the rest time interval may be user-adjustable to reflect the individual user&#39;s preferences and tolerance. 
   In alternate simplified embodiments of this invention the ring frequency counter or the ring length counter may be omitted so that the rest interval timer is started only in response to unduly lengthy ringing time or to overly repetitive ringing, respectively. In a minimal embodiment of the system only the ring length timer and the rest interval timer are provided, and both base interval timer and ring frequency timer are omitted, so that limited abuse protection is offered only against continuous rings of excessive length. 
   In yet another embodiment particularly useful with musical doorbells which once activated play a tune sequence of some length, the base time interval counter, the total ring length counter and ring frequency counter may be omitted, and only a rest time interval counter provided and connected for disabling the signaling device of the doorbell for a preset rest interval following a single actuation of the signaling device. In this embodiment the length of the tune is not under the control of the ringer device, the tune length being the same regardless of how often or how long the ringer is actuated once play of the musical tune has been initiated by the signaling device. Furthermore, actuations of the ringer device while the tune is playing do not normally result in further replays of the tune. The ringer is in effect disabled for the length of the tune once a single actuation is made of the signaling device. In such case, annoying rates of replay of the tune can be prevented by merely disabling actuation of the signaling device for a preset rest interval following a single actuation of the signaling device. In such case also, there is no base time interval to be measured and the base interval timer may be omitted or disabled and the ringer device connected such that a single actuation of the ringer device provides the input operative for starting the rest interval timer. Alternatively, the rest interval timer can be started upon completion of the tune played by the signaling device by means of a start input provided by a suitably modified signaling device, with appropriate adjustment to the length of the rest interval. 
   The long anticipated concept of the “smart home” equipped with a variety of sensors, switches and actuators controlled by a central processor programmed for optimizing and otherwise controlling various parameters of the home for the comfort and safety of its occupants. The “smart home” has been slow in becoming a commonplace reality perhaps because of the complexity and cost of interconnecting the many devices and systems required to operate such a home. Now, however, advances in wireless connectivity may be instrumental in finally bringing this concept to the broad marketplace. 
   A growing trend exists for wireless interconnection of household devices. For example, wireless door and window switches are commonly used in security systems, in place of costlier wired intrusion alarm systems. Low cost wireless doorbells are available, consisting of a doorbell switch unit and a remote receiver/announcer unit, both of which can be easily installed by the homeowner at convenient locations. Actuation of the doorbell switch triggers a radio transmission which actuates the announcer device of the receiver unit at a remote location. 
   In a “smart home” environment, multiple wired and wireless devices, including a wireless doorbell, can be controlled, monitored and actuated by a central processor suitably programmed for servicing the several devices. 
   In such an environment, the abuse resistant doorbell of this invention can be implemented largely or entirely in the software executed by the central processor. Appropriate program instructions perform the functions of the circuits depicted in  FIG. 1  including doorbell ring timing and ring counting. 
   These and other improvements, features and advantages will be better understood by reference to the following detailed description of the preferred embodiments in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic diagram of a doorbell system equipped with the abuse protection system according to this invention. 
       FIG. 2  is a flow chart diagram of a method for controlling abusive use of doorbells according to this invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   With reference to  FIG. 1  of the accompanying drawing, the numeral  10  generally designates the doorbell system equipped with the abuse protection system according to this invention. The doorbell system  10  includes a ring actuation device which in this example is a push button normally open electrical switch  12  connected by electrical conductors  14  to a remotely located signaling device such as an electric bell, ringer or buzzer  16  of a type which is readily available from electrical and hardware suppliers. Actuation of the ringer switch  12  by manually pushing the switch button closes switch  12  and completes the electrical circuit between electrical power source  18  and the bell  16 , thereby applying power to the bell and causing the bell to ring or buzz. 
   Pressing of the doorbell switch  12  produces a ring actuation input  22  which is a suitable waveform derived either directly from the electrical conductors  14  or through appropriate intervening signal conditioning circuits. The ring actuation input is fed to a base interval timer  36 , a ring frequency counter  20  and ring length timer  32 . The timer  36  and counter  20  require only pulse or other momentary inputs, while ring length timer  32  needs a continuous or periodic input coextensive with actuation of the doorbell switch  12 . 
   A first ring actuation input upon initial actuation of doorbell switch  12  starts base interval timer  36 . Timer  36  runs for a preset base time interval, at the end of which timer  36  self-resets to zero and also outputs a reset signal  25  to both the ring length timer  32  and ring frequency counter  20 , restoring timer  32  and counter  20  to zero states. 
   The base interval timer  36  measures a base time interval associated with stored limits in counter  20  and timer  32 . If either of the two stored limits is reached within the base time interval then a rest interval timer  26  is started and a cutoff switch is opened to prevent further ringing of the doorbell until the rest time interval has run. If, on the other hand, neither stored limit is reached within the base time interval, that is, if there is no abusive actuation of the doorbell switch  12 , then upon lapse of the base time interval the timer  36  resets itself as well as counter  20  and timer  32 , and a new base time interval is started and fresh ring frequency and ring length counts are accumulated by counter  20  and timer  32 , respectively. 
   The ring frequency timer  20  increments with every actuation of doorbell switch  12  and operates to count and store the number of closures of doorbell switch  12  accumulated during a current base time interval. Counter  20  includes a memory which stores a preset limit number of closures, for example a ring limit number of four doorbell switch closures. The stored current closure count is compared against the preset limit number of closures. If the doorbell is pressed four times, thereby closing switch  12  an equal number of times, the stored count of counter  12  reaches the preset limit, whereupon a counter output  24  starts the rest interval timer  26 . When timer  26  is started a timer output  28  opens doorbell cutoff switch  30  thereby breaking the doorbell circuit and disabling further actuation of the bell  16  by operation of the doorbell switch  12  for as long as cutoff switch  30  remains open. Rest interval timer  26  is preset for a rest interval, such as 30 seconds, for example, during which the cutoff switch  30  remains open. After the preset rest time interval has run, timer output  28  changes state and returns cutoff switch  30  to a closed state, thereby restoring continuity of the doorbell circuit. Upon lapse of the rest interval, timer  26  also outputs a system reset signal  40  to counter  20 , timer  32  and base interval timer  36 . The doorbell switch  12  is now again operative for actuating signaling device or bell  16 , and a new ring frequency count is accumulated and stored by counter  20  when the switch  12  is again pressed. 
   The ring length timer  32  receives a ring actuation input and operates to measure or accumulate the time length during which the switch  12  is closed and consequently the total ringing time of doorbell  16  during any current base time interval. A total ring time length is accumulated whether for a single continuous ring or a number of successive rings. The total ring time accumulated is compared to a maximum acceptable ring time limit stored in a memory of timer  32 . If the currently accumulated ring time in timer  32  reaches the stored maximum acceptable ring time limit, a timer output  38  starts rest interval timer  26 . As previously explained, when timer  26  is started the timer output  28  opens cutoff switch  30  thereby breaking the doorbell circuit and disabling further actuation of the bell  16  by operation of the doorbell switch  12  for as long as cutoff switch  30  remains open. After the preset rest time interval has run, timer output  28  changes state and returns cutoff switch  30  to a closed state, thereby restoring continuity of the doorbell circuit. Upon lapse of the rest interval, timer  26  also outputs a system reset signal  40  to timer  32 . The system reset signal resets to zero the accumulated ring time of timer  34  upon expiration of the rest time interval. Actuation of the doorbell switch  12  is now again operative for actuating signaling device or bell  16 , and a new total ring time is accumulated and stored by timer  32  during a new base time interval. 
   The base interval timer  36  and the rest interval timer  26  are independent of each other and the respective time lengths may be set to the end user&#39;s preferences or factory preset. For example, the base interval time may be longer, such as sixty seconds, while the rest time interval may be shorter, such as thirty seconds, to allow sufficient time for the occupants of the premises to respond to the door. 
   The doorbell protection system operates to guard against abuse of continuous ring bells which ring as long as the door bell is pressed, as well as those which play a prerecorded sound sequence in response to a momentary actuation of the doorbell. The ring length timer protects against overly long ringing of the doorbell, whether continuous or intermittent, while the ring frequency counter protects against abusively repetitious, even if brief, actuation of the doorbell. 
   Simplified forms of the protection circuit  10  are also contemplated. For example, in an abuse protection system intended for use with the more modern, tune playing doorbells, the length of the sound sequence is set by the stored tune and does not depend upon continuous pressing of the doorbell switch  12 . Also, repeated actuation of the doorbell switch is ineffective while a tune is playing in response to an earlier actuation of the doorbell switch. In such case, the ring length timer  32  may be omitted from the system  10  and only the ring frequency counter  20  left to detect abusive doorbell actuation. 
   Conversely, in some systems it may be desirable to provide only the ring length timer  32  without the ring frequency counter  20 . In a minimal embodiment of the system  10  only the ring length timer  32  and the rest interval timer  26  are provided, and both base interval timer  36  and ring frequency timer  20  are omitted, so that limited abuse protection is offered only against continuous rings of excessive length. 
   In another embodiment particularly useful with such musical tune playing doorbells, the base time interval counter  36 , the total ring length counter  32  and ring frequency counter  20  are omitted, and only a rest time interval counter  26  is provided and connected for disabling the signaling device  16  for a preset rest interval following a single actuation of the ringer device  12 . In this embodiment the tune length is the same regardless of how often or how long the ringer  12  is actuated once play of the musical tune has been initiated by the signaling device  16 . In effect, the ringer  12  is disabled for the duration of the tune once a single actuation is made of the signaling device  16 . In such case, annoying rates of replay of the tune can be prevented by merely disabling actuation of the signaling device  16  for a preset rest interval following a single actuation of the ringer device  12 . This last embodiment can be implemented by connecting the ring actuation input  22  directly to the rest interval timer start input  34 , so that upon a first actuation of the ringer device  12  the rest interval count of counter  26  is started during which output  28  operates to open disabling switch  30 . Also, instead of starting the rest interval timer start input  34  based upon actuation of the ringer device  12 , an equivalent rest timer interval start input can be derived based upon termination of play of the musical tune generated by signaling device  16 , rather than upon actuation of the ringer device  12 . That is, the rest interval timer  26  is started when the musical tune ends, so that the disabling switch  30  is actuated at the end of the tune for the preset rest interval. In this last form of the invention the musical tune signaling device  16  is constructed to deliver an appropriate start input  46  to the rest interval timer  26  as suggested by the dotted line in the drawing. 
   A display  42  may be provided adjacent to the doorbell switch  12  to inform the visitor that the doorbell is momentarily disabled, for example by way of a flashing LED or other suitable warning device. The display  42  may include a countdown timer  44  showing lapse of the rest interval. For example, the timer display in the drawing shows 43 seconds remaining of the rest interval. 
   It is understood that the timer and counter circuits of the doorbell abuse protection system  10 , including the cutoff switch  30 , may be implemented in the form of a solid state integrated circuit which can be included at low cost in doorbell ringers for commercial distribution. 
     FIG. 2  shows a block diagram illustrating a sequence of steps executable in software for implementing the doorbell abuse system according to this invention. The process illustrated in  FIG. 3  essentially implements the functions already described above in connection with  FIGS. 1 and 2 , and one skilled in the art will be able to develop a similar or equivalent flow chart from those Figures and the preceding description. The diagram of  FIG. 3  is therefore provided primarily for purposes of clarity and example, without limitation to the particular organization or sequence shown. 
   Some wireless doorbell actuators, such as a doorbell pushbutton and associated radio transmitter, operate by transmitting a radio command signal of fixed duration in response to each actuation of the doorbell actuator, regardless of the duration of the actuation, e.g., no matter how long the doorbell pushbutton switch is held depressed. In such cases the most likely type of abuse will be an excessive number of actuations of the doorbell rather than a single excessively long ringing or multiple ringings of varying length and in rapid sequence. This is because, by design, such wireless doorbells respond to each actuation with a ring or other signal of fixed duration. Nonetheless, the method described below contemplates the possibility of a wireless doorbell installation capable of operation in a continuous mode where the bell or other signaling device is responsive to the length of actuation of the actuating device such as a push button switch by signaling or ringing for a time equal or proportional to the length of the actuation. 
   Turning now to  FIG. 2 , flow chart  100  has a step  110  wherein a ring signal is received from a doorbell actuator such as a push button switch mounted near a doorway. Reception or detection of the ring signal starts a base interval timer in step  112  if the initial ring count of the ring frequency counter is equal to zero and increments a ring frequency counter at step  114 . 
   If the ring signal is of a continuous type, i.e. one causing continuous actuation or ringing of the signaling device so long as the ring actuator is held in actuating position, e.g. a bell push button held pressed, then the uninterrupted ring length is timed at step  116 , and if the uninterrupted ring length exceeds a preset acceptable maximum ring length of TL, step  118  starts a rest interval timer during which interval the ringer or signaling device, e.g. the doorbell, is disabled from actuation by further operating of the doorbell actuating device. The signaling device remains disabled until expiration of the rest interval TR whereupon step  120  resets the ring length counter and the rest interval counter and reenables the signaling device. 
   If, instead, the continuous ring signal length is of acceptable duration (less than TR), and the ring signal derived from the ring actuator is of continuous duration, rather than a ring command of fixed length, and end of ring is detected and the ring timer is stopped in step  122 , and the measured time of the ring length is stored and accumulated in the ring length timer. The accumulated ring time is compared against TR and if found greater than TR step  124  starts a rest interval timer during which interval the ringer or signaling device, e.g. the doorbell, is disabled from actuation by further operating of the doorbell actuating device. The signaling device remains disabled until expiration of the rest interval TR whereupon step  120  resets the ring length timer and the rest interval timer and reenables the signaling device. 
   In step  114  the number of ring actuation signals, whether commands of fixed duration or continuous type ring signals, is counted and accumulated by the ring frequency counter during each base time interval of the base interval timer. This number is compared against a stored predetermined and preferably user adjustable acceptable ring frequency number FC and if found to be greater than FC, step  126  starts a rest interval timer during which interval the ringer or signaling device, e.g. the doorbell, is disabled from actuation by further operation of the doorbell actuating device. The signaling device remains disabled until expiration of the rest interval TR whereupon step  120  resets the ring length counter and the rest interval counter and reenables the signaling device. 
   In installations having ring signaling devices inherently limited to ring signals of fixed length only, the system and method of this invention may be simplified by limiting protection to excessive number of actuations of the signaling device, i.e. an annoyingly lengthy series of repeating rings, and omitting the portions designed to prevent abuse by excessively long continuous ring duration, whether a single continuous ring or multiple ring adding to excessive cumulative ring time within some arbitrary base interval. 
   In some currently available wireless door bells operation of the actuating device, e.g. the push button switch mounted by the door results in a ring signal of fixed duration, and if the actuating switch is held depressed, the ring signal repeats until the switch is released. In such case the number of successive ring repetitions per base interval may be counted as the basis for assessing whether the ringing is abusive. The successive ring signals are counted in the ring frequency counter and is the count is found to exceed a predetermined stored acceptable number of rings, the rest interval timer is activated and the signaling device is disabled for the duration of the rest interval. After the rest interval expires the signaling device is reenabled. 
   The base interval timer at step  128  provides a maximum time period before all timers and counters are reset to an initial state and the process is restarted at step  110  with detection of a ring start signal. 
   As explained previously, the length of the base interval may be equal to or greater than the length of the rest interval. Typically, the base interval serves as a global system reset regardless of whether the rest interval timer has been activated by ringing activity during the base interval initiated by a first and possibly single actuation of the actuating device, e.g. a single brief push of the door bell switch. While not the preferred condition, the preset base interval may even be shorter than the preset rest interval without thereby significantly impairing operation of the system, as the result is to reset the system prior to expiration of the rest interval and perhaps allowing renewed ringing of the door bell somewhat sooner than would otherwise be allowed by full running of the rest interval. 
   While preferred and alternate embodiments of the invention have been described and illustrated for purposes of illustration and clarity, it will be understood that many changes, substitutions and modifications will become apparent to those having only ordinary skill in the art without thereby departing from the scope of the invention as defined in the following claims.