Abstract:
A rodent control device generates a pulsating, interrupted electromagnetic field via one or more coil(s) and induces it onto the power line wiring in a building via core(s) linked to the coil(s). The rodent control device circuit is microprocessor controlled which allows automatic sensing of line voltage cycle rates and precise control of coil switching circuitry. The coil(s) are connected to the microprocessor to provide a coil monitoring signal via which the microprocessor detects abnormalities in the coil(s) such as shorts or open circuits. Upon detection of such an abnormality, the microprocessor shuts off control signals to the coil and to an LED indicator until a normal coil condition is sensed. The microprocessor also provides a timed rest signal for shutting down the device for, for example, 2 minutes out of every 6 minute period as a power saving feature.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a rodent control device, and, more particularly, to such a rodent control device which generates a pulsating electromagnetic field within a building. The device is controlled by a programmed microprocessor which precisely cycles a coil on and off at a predetermined duty cycle rate while cycling the device itself on and off, detects and compensates for power line cycle rates by adjusting duty cycle rates of the pulsating field, and detects circuit abnormalities and shuts down or does not energize the coil or LED indicator in the event an abnormality is detected. 
     BACKGROUND OF THE INVENTION 
     A number of different electronic rodent control devices have been devised, which have been of varying degrees of effectiveness. U.S. Pat. No. 4,802,057, which is assigned to the present assignee, is an example of such a device. In the &#39;057 patent, a rodent control device incorporates a low voltage integrated circuit timer to generate a pulsed output at an approximate frequency of one pulse per second, with the pulses being periodically stopped for an interim period. An opto-coupler receives the timed pulses from the timer circuit and, in turn, provides an output signal to a voltage dividing circuit which gates a triac switch. The triac is thus periodically switched on at the timed rate of about one pulse per second and, in response, completes a circuit from a first power lead through a coil to a second power lead via the triac. The coil has a core associated therewith which is connected to the second power lead and which induces a pulsed, interrupted electromagnetic field onto the power line such that the entire building wiring system becomes a radiator for the pulsed and interrupted electromagnetic field. 
     The rodent control device described in the &#39;057 patent has proven to be a very successful consumer product. However, the circuit in the &#39;057 patent is relatively expensive since it requires the use of discrete components, including the rather expensive opto-isolator. Furthermore, it would be desirable if the device could sense abnormal coil conditions, such as coil short and open circuits, and cease operation until normal coil conditions resume. Finally, due to varying line cycle conditions, it would be preferable if the device could automatically adapt its timing cycle for differing power line cycles. 
     The present invention is intended to be an improvement on the circuit described in the &#39;057 patent. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a rodent control device which generates a pulsating, interrupted electromagnetic field via one or more coil(s) and induces it onto the power line wiring in a building via core(s) linked to the coil(s). The rodent control device uses a circuit controlled by a microprocessor which senses line voltage cycle rates and times the application of electromagnetic pulses to the power line based upon the line voltage cycle rate. The coil(s) are connected to the microprocessor to provide a coil monitoring function via which the microprocessor detects abnormalities in the coil(s) such as shorts or open circuits. Upon detection of such an abnormality, the microprocessor shuts off gate control signals to a coil switching triac and signals to an LED indicator until a normal coil condition is sensed. The microprocessor provides several precise timing cycles including a cycle for activating an LED indicator in synchronism with a time cycle for controlling the application of pulses to the coil(s). In addition, a device rest signal is generated by the microprocessor, for example, for 2 minutes out of every 6 minute period as a power saving feature. 
     OBJECTS AND ADVANTAGES OF THE INVENTION 
     The principal objects of the present invention include: providing an improved rodent control device; providing such a rodent control device which applies an accurately timed electromagnetic pulse to a power line to repel rodents; providing such a rodent control device which is controlled by a microprocessor; providing such a rodent control device which does not require an opto-isolator to isolate the logic circuitry from the line voltage; providing such a rodent control device which is self adapting based upon the particular cycle rate of the connected line voltage; providing such a rodent control device in which the microprocessor senses coil conditions and shuts off any gate control signals to a coil operating triac and to an LED indicator when abnormal coil conditions exist, such as short or open circuits; and providing such an rodent control device which is economical and which is particularly well adapted for its intended purpose. 
     Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. 
     The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of an improved rodent control device in accordance with the present invention. 
     FIG. 2 is a schematic circuit diagram of the improved rodent control device of FIG.  1 . 
     FIG. 3 is a flow chart diagram illustrating the start-up procedures for the microprocessor controlling the circuit of FIG.  2 . 
     FIGS. 4A,  4 B, and  4 C are flow chart diagrams illustrating the programmed logic of the microprocessor controlling the circuit of FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure. 
     Referring to FIG. 1, an inventive rodent control device is illustrated and generally indicated at  1 . The rodent control device  1  is contained within a housing  2  with an opening  3  within which an LED indicator  4  is positioned. A standard male power plug  5  extends outward from the housing  2 . 
     Referring to FIG. 2, a schematic diagram illustrates a circuit  11  of the rodent control device  1 . In the circuit  1 , ordinary 120 VAC household line voltage is applied between terminals  12  and  13 . A resistor R 1  and capacitor C 1  provide a current limiting function. A power supply includes diodes D 1  and D 2 , which form a full wave rectifier, capacitor C 2 , which provides a voltage spike elimination function, capacitor C 3  is a filter while zener diode ZD 1  limits voltage applied to VCC (pin  5 ) of microprocessor IC 1  to 5 volts DC. Direct line voltage is applied from terminals  12 ,  13  to P 32  (pin  9 ) and GND (pin  14 ) of the microprocessor IC 1 . P 32  acts as an interrupt input for assessing line voltage frequency, as will be explained below. 
     Capacitor C 4  and resistor R 2  collectively provide a low cost clock connected to clock pins  6 ,  7  of the microprocessor IC 1 . P 00  (pin  11 ) of the microprocessor IC 1  is connected to LED 1 , which is the LED indicator  4  described above. P 01  (pin  12 ) of the microprocessor IC 1  provides an output gating signal to the triac Q 1  via current limiting resistor R 5 . When the triac Q 1  is gated ON by a high signal on pin P 01 , it closes a circuit from line voltage terminal  12 , through coil CL 1  and (optional) coil CL 2 , and back to line voltage terminal  13 . 
     P 33  (pin  18 ) of the microprocessor IC 1 , is a coil monitoring input connected via a coil monitoring lead to the junction between resistor R 4  and diode D 3 . This coil monitoring input P 33  senses coil conditions during periods when the triac Q 1  is switched ON in order to detect abnormal conditions such as coil open or short circuits. In other words, when operation of the coil CL 1  is normal, a high logical input will be impressed on pin P 33 , but abnormal conditions in the coil CL 1  will result in a low logical input on pin P 33 . 
     Resistor R 6  stabilizes the triac Q 1  to insure that spurious signals on the pin P 01  do not inadvertently trigger the triac Q 1 . Capacitor C 5  and resistor R 7  are a snubber circuit which prevents induction “kicks” from coils CL 1  and C 12  from latching up the triac Q 1 . 
     Referring to FIG. 3, an initial start-up loop for the microprocessor IC 1  is illustrated. At block  21 , the IC 1 , which can be a Z 86  processor, is started up and, at block  22 , the registers, ports and stacks are initialized, and, at block  23 , the Seconds, Minutes, and Scratch Registers are initialized to their programmed initial values. Block  24  represents a “mumble mode” loop in which the microprocessor IC 1  is waiting for a line voltage interrupt at pin P 32 . 
     Referring to FIGS. 4A,  4 B, and  4 C, collectively form a logical flow chart of the program for the microprocessor IC 1  after an initial line voltage interrupt (block  25 ) is sensed on pin P 32 . At block  28 , a decision is made as to whether this is the first interrupt, and, if so, at block  29 , the line cycle rate is checked. This is done by timing the interval between the first and second interrupts and setting a line cycle register to 1 if the cycle rate is 60 Hz and to 0 if the cycle rate is 50 Hz. This check is performed only on the first “Pass” or first two interrupt signals. At block  30 , the line cycle register value is compared to 1, and, if 1, at block  31 , the FSEC register comparison (block  34  described below) is set to  29 , but if it is 0, at block  32 , then the FSEC register comparison is set to  27 . 
     As would be understood by a person skilled in assembler language programming, a compare block such as block  30 , shown in FIG. 4A, represents a subtraction operation and the Z result indicates that the quantities compared were the same (i.e. that the difference was equal to zero). Conversely, the NZ result indicates that the quantities compared were not the same (i.e. that the difference was not zero). 
     After the first interrupt, at block  33 , the FSEC register is incremented by 1. The FSEC register thus counts interrupts, which occur every half voltage cycle. At block  34 , the FSEC register value is compared to 29 or 27, depending upon the line voltage cycle, and the cycle repeated until a count of 29 or 27 interrupts (approx. ½ second) is reached. Then, at block  35 , the FSEC register is cleared, and, at block  41 , the LED register is incremented. Only the least significant digit of the LED register is used, and, at block  42 , this least significant bit is compared to 1. If it equals 1, then, at block  43 , the LED indicator  4  (LED 1 ) is turned On. By contrast, if the least significant bit of the LED register is 0, then, at block  44 , the LED indicator  4  is turned Off and, at block  45 , the LED register is cleared. The loop encompassed by the blocks 41-45 cycles the LED indicator  4  On for ½ second and then Off for the next ½ second. 
     At block  51 , the least significant bit of the Coil Register is compared to 1, and, if it equals 1, then the coil operation loop of FIG. 4C is entered. If the least significant bit of the coil register is 0, then the time loop of FIG. 4B is entered. 
     Referring to FIG. 4C, at block  52 , the LED register is again compared to 1 and, if equal to 1, then the coil CL 1 , and, optionally, the coil CL 2  are turned Off, at block  53 , by switching Off the triac Q 1  via the pin P 01  of the microprocessor IC 1 . If the LED register is not equal to 1, then, at block  54 , the Pass One Register is compared to 1, and, if it does not equal 1, then, at block  55 , the coil(s) CL 1  and CL 2  are turned On via the triac Q 1 . Conversely, if the Pass One register is not equal to 1, then, at block  61 , the Pass One register is cleared and, at block  62 , a 0.1 Second delay is instituted to allow time to check coil status. At block  63 , the Coil Present register is compared to 1, and, if equal to 1, then at block  64 , the coil(s) CL 1  and CL 2  are turned Off by switching Off the triac Q 1  and the LED indicator  4  and the loop is returned to the top of FIG.  4 A. Conversely, if the Coil Present register is not equal to 1, then the timing loop of FIG. 4B is entered, just as it is from blocks  53  and  55 . The loop represented by FIG. 4C thus turns the coil off and on at the same rate as the LED indicator  4 , if the coil present register is normal. 
     Referring to FIG. 4B, at block  71 , the Seconds register is incremented, and, at block  72 , the Seconds register is compared to the number  119 . The loop of FIG. 4A is thus repeated until the Seconds register is equal to  119 . When the Seconds register is equal to  119 , indicating the lapse of 1 minute, then, at block  73 , the Seconds register is cleared and, at block  74 , the Minutes register is incremented. At block  75 , the Minutes register is compared to 4, and, if equal to 4, then the coil register is cleared at block  81  and the loop returns to the top of FIG.  4 A. Conversely, if the Minutes register is not equal to 4, then the Minutes register is compared to 6 at block  82 . If it is equal to 6, then, at block  83 , the Minutes register is cleared and, at block  84 , the Coil register is turned back On (i.e. reset to 1) and the loop is returned to the top of FIG.  4 A. If the Minutes register is not equal to 6, then the loop is also returned to the top of FIG.  4 A. The loop represented in FIG. 4B, encompassing blocks  71 - 84 , serves to cycle the rodent control device  1  such that it is activated for 4 minutes and then deactivated for 2 minutes. Clearly, any other On/Off cycle time can be set by varying the comparison steps  75  and  82 . 
     While the rodent control device  1  has been described and illustrated in a particular embodiment, changes could be made to the circuitry or the digital logic without affecting the viability of the invention. For example, many different platforms and pin configurations can be used for the microprocessor IC 1 . Accordingly, it is thus to be understood that while certain forms of the present invention have been illustrated and described herein, it is not to be limited to the specific forms or arrangement of parts described and shown.