Abstract:
A controller for outdoor lighting systems turns lights on and off at predetermined times during the day which are designated by a user. The turn on time is set when the user first turns on the lights. The turn off time is fixed by allowing the user to specify the amount of time that the lights will stay lit. The controller repeats the on-off sequence every 24 hours unless it is reprogrammed. Accurate timing is maintained by counting the pulses in standard 120 V, 60 Hz, line current. A manual override is provided which does not interfere with the programmed time sequence.

Description:
FIELD OF THE INVENTION 
     The invention relates to the field of controllers for electrical devices, and more particularly to controllers for outdoor lighting systems. 
     BACKGROUND OF THE INVENTION 
     There are many uses for outdoor lighting systems. Many people find it desirable to have outdoor lights around their house. These lights add aesthetics to the house, provide an element of security by illuminating dark areas, and often increase the value of house and property. Parks and other public areas also benefit from the use of outdoor lights. 
     One limitation on the use of outdoor lights, however, is a mechanism for turning them on and off. It is usually not desirable to have the lights stay on all night, as this results in increased power usage and attendant costs. 
     Previous types of outdoor lighting controllers utilized a photocell to turn the lights on and off. As evening approached, the light falling on the photocell decreased. When the photocell sensed a certain level of dimness, the lights were turned on. The lights remained on until the photocell sensed that the amount of light falling on the photocell had reached a certain brightness. This type of controller had the limitations of keeping the lights on all night and not allowing the user to turn the lights on at any given time. The present invention overcomes these limitations by allowing the user to turn the lights on at any desired time and specify the amount of the time that the lights will remain lit. 
     SUMMARY OF THE INVENTION 
     The present invention comprises a controller for outdoor lighting systems. The controller allows the lights to be turned on and off at predetermined times that are designated by a user. The user turns the lights on and selects how many hours the lights are to remain lit. After the selected number of hours, the lights automatically turn off. The turn-on/turn-off sequence repeats every 24 hours unless the controller is reprogrammed. The controller monitors accurate timing by counting pulses in standard 120 volt, 60 Hertz, AC. A manual override is provided that does not interfere with the programmed times. 
     The controller of the present invention overcomes problems that are present in prior outdoor lighting systems. The automatic turn-off feature eliminates the need for the user to manually operate the lights. Because the controller&#39;s programmed sequence repeats every 24 hours, the user can set the controller once and the lights will automatically turn on at the selected time each day, and then automatically turn off after they have been lit the desired amount of time. The present invention also overcomes the problems of prior photocell type controllers which keep lights turned on all night. With the present invention, the user can program the lights to turn on at dusk, and remain on for only a few hours, as opposed to staying on until dawn. For example, a user may wish to turn the lights on at 8:00 p.m. and have them remain lit for 2 hours. This results in reduced power consumption and less cost to the user. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a functional block diagram of the present invention. 
     FIG. 2 is an electronic schematic of the preferred embodiment of present invention. 
     FIG. 3 is a block diagram showing the relationship between the present invention and other elements of an outdoor lighting system. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An electrical controller for the control of outdoor lighting systems is described. Throughout the description the same numbers are used to designate the same elements of the invention. 
     Referring first to FIG. 1, a functional block diagram at the present invention is illustrated. The main elements of the controller are the pulse generator 23, the programmable divider circuit 33, the shift register 35 and the output latch 60. Power is supplied to the controller through the connector 10 from the power cord 9. The pulse generator 23 changes ordinary household current (120 volts AC) into a square wave pulse train. These pulses are then counted by the programmable divider circuit 33 which, in the preferred embodiment, generates an output pulse once every hour. 
     The shift register 35 contains a number of bits arranged in a serial manner. The preferred embodiment utilizes 24 bits--one for each hour of the day--but a different number can be used. The value of the bits in the shift register 35 are either 0 or 1. When the shift register 35 receives an output pulse from the programmable divider circuit 33, the contents of the shift register are shifted one position to the left. The contents of the most significant, or leftmost, bit moves to the least significant, or rightmost, position. 
     The output latch 60 monitors the most significant bit location. When the contents of this location change from a 0 to a 1 the output latch 60 generates a signal that turns the lights on. When the contents of the most significant bit changes from 1 to 0 the output latch turns off the lights. A manual override unit 59 is connected to the output latch. The manual override allows the lights to be turned on and off without affecting the timing circuits. 
     The user interface 24 performs two main functions. First it turns the lights on and initiates the timing sequence by resetting the programmable divider circuit 33 and the shift register 35. Second, it sets the value of at least one of the bits contained in the shift register to a value of 1. In the preferred embodiment the user interface 24 sets the most significant bit and up to seven additional bits to a value of 1, and the remaining bits to a value of 0. The bits set to a value of 1 are all adjacent to each other. Thus, the preferred embodiment allows the user to program the controller to keep the lights on for a total of seven hours. 
     The present invention is only one element of an outdoor lighting system. FIG. 3 shows a typical system incorporating the present controller 1. The system illustrated also has a power module 2 and the lights themselves 3. As shown, the controller does not actually drive the lights, but drives the power supply. It is to be understood that when the present description states that the controller &#34;turns on&#34; or &#34;turns off&#34; the lights 3, it may either do so directly or send a signal to the power supply to turn the lights on or off. 
     A more detailed description at the invention will now be provided with reference to FIG. 2. Power enters the controller through the power cord 9 and connector 10. In the preferred embodiment the 120 volt AC power is applied across connector pins 10a and 10f, with ground being connected to connector pin 10F. Resistor 11 and diode 12 are used to half-wave rectify the AC signal and present a low voltage direct current signal to capacitor means 13 and zener diode 14. The voltage level at the anode of diode 12 changes from a low value to a high value as the half-wave rectified AC signal rises. In the preferred embodiment, the input frequency of the AC signal is 60 Hertz and the anode of the diode 12 changes to a high state approximately every 16.67 milliseconds. The change in state at the anode of diode 12 is sensed by the input of logic gate 17. In the preferred embodiment logic gate 17 is an OR gate. Resistor 18 and capacitor 19 provide filtering and hysteresis such that a clean filtered square wave signal is present at the output 20 of the OR gate 17. 
     Integrated circuits 25-29 are counters which form a programmable divider circuit. The input 21 to the programmable divider circuit is connected to the output of the OR gate 17. The programmable divider circuit counts the number of pulses output from the OR gate, and, after a predetermined number of pulses, outputs a signal at the output 22 of the programmable divider circuit. In the preferred embodiment, the programmable divider circuit counts 216,000 input pulses before generating an output pulse. Since the preferred embodiment inputs a pulse to the programmable divider circuit approximately each 16.67 milliseconds, the programmable divider circuit generates an output pulse once every hour. It will be appreciated by those skilled in the art that different numbers of input pulses may be counted in order to generate output pulses at different time intervals. 
     The output 22 of the programmable divider circuit is connected to a serial shift register, which in the preferred embodiment, is comprised of integrated circuits 30-32. Each of the integrated circuits 30-32 is an 8 bit parallel load serial shift register and in the preferred embodiment the registers connected serially. Thus, a single 24 bit serial shift register is created. For the purposes of this disclosure, the bits in the shift register will be described as being arranged in a horizontal, left to right relationship with the most significant bit being the leftmost bit. 
     Whenever an output pulse appears at the output 22 of the programmable divider circuit 33, the bits in the shift register change position. Each bit moves one position to the left with the leftmost bit rotating to the rightmost position. Thus, in the preferred embodiment, the bits change position once each hour. One bit location is monitored as the output 36 of the serial shift register 35. In the preferred embodiment, the most-significant bit is monitored. 
     The signal at output 36 of the shift register passes through signal line 62 to the output latch 60. The output latch acts as an edge triggering device. Resistor 66 provides a feedback signal to OR gate 38. Because of the feedback, the output of OR gate 38 will only change state when signal line 62 changes. When the output of the shift register 35 changes from a low value to a high value, the output of OR gate 38 latches at a high value. Conversely, when the output of the shift register 35 changes from a high value to a low value, the output of OR gate 38 latches at a low value. The output of OR gate 38 is fed into OR gate 39. The output of OR gate 39 is connected to the connector 10 at the connector pin 10d. When the output of the OR gate 39 is high, the lights are on. When the output is low the lights are off. When the programmed number of hours have passed, the output of the shift register will change to a low value thus turning the lights off. 
     The operation of the user interface 24 will now be described. The user interface consists of switches 34 and 55 and AND gate 54. In the preferred embodiment, switch 55 is normally open and is of the momentary contact type. The inputs to AND gate 54 are pulled low through resister 53 when switch 55 is open. Thus, the output of AND gate 54 is also held low. When Switch 55 is closed, the inputs of AND gate 54 are high and the output of AND gate 54 is consequently pulled high. This signal travels over reset line 61 to integrated circuits 25-29 which comprise the programmable divider circuit and integrated circuits 30-32 which comprise the shift register. A high signal level on the reset line causes the dividers in the programmable divider circuit to be reset to zero. This initiates the timing sequence. Also, each of the 24 bits in the shift register is loaded with a value of 0 or 1 as will be more fully described below. Closing of switch 55 also causes a high signal to appear at the output 36 of the shift register 35, which, as described above, causes output latch 60 to generate a signal which turns the lights on. 
     The manner in which the bits are loaded into the shift register will now be described. In the preferred embodiment, the inputs 31a--31h and 32a--32h to the 8-bit shift registers on integrated circuits 31 and 32 are tied to ground through lines 63 and 64, respectively. Also, the input 30h to bit number 8 of the 8-bit shift register on integrated circuit 30 is tied to ground through line 65. This causes the least significant 17 bits of the 2 bits in the shift register 35 to be set to zero when switch 55 is closed. In the preferred embodiment, these comprise bits 8-24. The preferred embodiment thus allows bits 1-7 of the 24 bit register to be programmed with either a 0 or 1 depending on how long the user desires the lights to remain turned on. 
     Bits 1-7 are programmed with the use of switch 34 and diodes 47-52. In the preferred embodiment, switch 34 is a slide switch with seven selectable positions. When the switch 34 is in position 34i all of the inputs 30a-30g are tied to ground through resisters 40-46. However, when switch 34 is in any other position, some of the inputs are connected to a voltage on line 63. For example, when switch 34 is in position 34c, input 30c is connected directly to voltage line 63. Also, current flows through diodes 47 and 48 and resistors 40 and 41, thereby causing high signals to appear at inputs 30a and 30b as well as 30c. Inputs 30d-30g are isolated by means of diode 49, which is reverse-biased, and remain tied to ground through resistors 43-46. Therefore, when switch 34 is in position 34c and switch 55 is closed thereby enabling shift register to be loaded, a value of 1 is loaded into the three most significant bits of the shift register and the remaining bits are loaded with a value of zero. 
     Every hour, a pulse from the programmable divider circuit 33 will shift the bits in the shift register one bit to the left. Thus in the foregoing example, after three hours, the most significant bit in the shift register 33 will change to a low value. As described above, this will cause the output latch to generate a signal to turn the lights out. Since there are 24 total bits in the shift register 33, the bits will return to their original positions in 24 hours, or one day, after the lights are initially turned on. At that time the most significant bit will go high and the lights will turn on. A specific illustration of the use of the present invention will be given in the following example. A user may wish to have the lights turn at 8:00 p.m. and stay lit for 3 hours. To do this, the user would simply set switch 34 in position 34c and wait until 8:00 p.m. At that time, the user would press Switch 55, thus turning on the lights. The lights would remain on for 3 hours. The next day, the lights would again turn on at 8:00 p.m. and stay lit for 3 hours. This sequence would repeat until the controller was reprogrammed. 
     A manual override is provided by switches 56 and 57. Switch 56 presents a high value to the input of the OR gate 38. Switch 57 presents a low value to the input of the OR gate 38. As described above, the output of OR gate 38 will latch in a particular state because of the feedback through resistor 66. Thus, when the lights are turned on or off by switches 56 or 57, respectively, they will stay in that condition until signal line 62 changes state or a switch is activated. These switches thus allow the lights to be turned on and off without affecting the timing circuit. 
     The foregoing description of the invention has set forth specific details regarding specific components and arrangements of the present invention. In other instances, details of well-known components have been ommitted so as not to unneccessarily obscure the invention. For example, in the preferred embodiment, all of the integrated circuits use CMOS technology. Each chip has buffered inputs with diode clamps. This prevents the signals entering the chips from exceeding a predetermined voltage range and prevents noise spikes. It will be apparent to those skilled in the art that these details can be changed without departing from the spirit of the present invention. For example, and without limitation, in the user interface 24 the switch 34 may be of the rotary or push-button type and additional bits may be programmed, allowing the lights to remain on for longer periods. Also, more than 24 bits may be employed in the shift register. For example, 48 bits would allow the user to program the controller to turn the lights off at 30 minute intervals as opposed to one hour intervals. Any of these options may be employed by those skilled in the art as a matter of design choice, without departing from the spirit of the present invention.